POSITIVE FLOW EXCAVATOR AND CONTROL METHOD AND CONTROL DEVICE THEREFOR, AND CONTROLLER

Abstract

 Embodiments of the present application provide a positive flow excavator and a control method and control device therefor, and a controller. The control method for the positive flow excavator comprises: obtaining a pilot pressure of a control mechanism; determining an action type of the positive flow excavator according to the pilot pressure; determining a first preset power proportion of a first main pump and a second preset power proportion of a second main pump according to the action type, wherein the sum of the first preset power proportion and the second preset power proportion is 100%; respectively determining a first control current of a first main pump solenoid valve and a second control current of a second main pump solenoid valve according to the first preset power proportion and the second preset power proportion; and respectively outputting the first control current and the second control current to the first main pump solenoid valve and the second main pump solenoid valve, so as to control the output power of the first main pump and the output power of the second main pump. According to the embodiments of the present application, the throttling loss can be avoided, the controllability is ensured, and both the fuel economy and operation efficiency are achieved.

Description

Cross Reference to Related Applications

[0001] This application claims benefits of Chinese Patent Application No. 202210770604.9, filed on June 30, 2022, the content of which incorporated herein by reference.

Field of the Invention

[0002] The present application relates to the technical field of excavator control, in particular to a positive flow excavator and a control method and control device therefor, and a controller.

Background of the Invention

[0003] When an excavator works, there are a large amount of complex actions. While guaranteeing operation efficiency, coordination of the actions needs to be taken into account. In order to achieve reasonable flow allocation, it is usually necessary to adjust the flow of the complex actions by adding logic valves. Taking boom raising plus swing as an example, to guarantee a height of boom raising, a boom priority over swing logic valve is added, and at the same time, dual pumps adopt a fixed power allocation ratio to achieve flow allocation, thereby guaranteeing coordination between the boom and a swing action. However, the presence of the logic valve causes an increase in system back pressure, resulting in energy loss. Even during other actions, the logic valve still operates, resulting in throttling losses and affecting the overall operation efficiency and fuel efficiency. Therefore, it is urgent to propose a technical solution to solve the above-mentioned technical problems in the prior art.

Summary of the Invention

[0004] Objectives of embodiments of the present application are to provide a positive flow excavator and a control method and control device therefor, and a controller, to solve the above-mentioned technical problems in the prior art.

[0005] In order to implement the above objectives, a first aspect of the present application provides a control method for a positive flow excavator. The positive flow excavator includes a control mechanism, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve. The control method includes: obtaining a pilot pressure of the control mechanism; determining an action type of the positive flow excavator according to the pilot pressure; determining a first preset power proportion of the first main pump and a second preset power proportion of the second main pump according to the action type, wherein a sum of the first preset power proportion and the second preset power proportion is 100%; respectively determining a first control current of the first main pump solenoid valve and a second control current of the second main pump solenoid valve according to the first preset power proportion and the second preset power proportion; and respectively outputting the first control current and the second control current to the first main pump solenoid valve and the second main pump solenoid valve, so as to control output power of the first main pump and output power of the second main pump.

[0006] In the embodiment of the present application, the pilot pressure includes: an arm in pilot pressure, an arm out pilot pressure, a swing pilot pressure, a left traveling pilot pressure, a right traveling pilot pressure, a boom raising pilot pressure, a boom lowering pilot pressure, a bucket close pilot pressure and a bucket dump pilot pressure. The action type is selected from any one of the following: a composite action of boom raising plus swing; a composite action of arm out plus bucket dump; and other actions than the composite action of boom raising plus swing and the composite action of arm out plus bucket dump.

[0007] In the embodiment of the present application, determining the action type of the positive flow excavator according to the pilot pressure includes:

in a case that the pilot pressure meets a first condition, determining that the action type is the composite action of boom raising plus swing, wherein the first condition includes: both the boom raising pilot pressure and the swing pilot pressure being greater than or equal to a preset opening pressure, and the arm in pilot pressure, the arm out pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure and the bucket dump pilot pressure being all smaller than the preset opening pressure;

in a case that the pilot pressure meets a second condition, determining that the action type is the composite action of arm out plus bucket dump, wherein the second condition includes: both the arm out pilot pressure and the bucket dump pilot pressure being greater than or equal to the preset opening pressure, and the boom raising pilot pressure, the swing pilot pressure, the arm in pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure and the bucket close pilot pressure being all smaller than the preset opening pressure; and

in a case that the pilot pressure does not meet any one of the first condition and the second condition, determining that the action type is the other actions.

[0008] In the embodiment of the present application, determining the first preset power proportion of the first main pump and the second preset power proportion of the second main pump according to the action type includes: in a case that the action type is the composite action of boom raising plus swing, determining the first preset power proportion and the second preset power proportion according to a ratio of the boom raising pilot pressure to the swing pilot pressure; in a case that the action type is the composite action of arm out plus bucket dump, determining the first preset power proportion and the second preset power proportion as a first preset value and a second preset value respectively; and in a case that the action type is the other actions, setting both the first preset power proportion and the second preset power proportion to be 50%.

[0009] In the embodiment of the present application, determining the first preset power proportion and the second preset power proportion according to the ratio of the boom raising pilot pressure to the swing pilot pressure includes: in a case that the ratio is within a preset ratio range, determining the first preset power proportion and the second preset power proportion as a third preset value and a fourth preset value respectively; in a case that the ratio is smaller than a lower limit value of the preset ratio range, setting both the first preset power proportion and the second preset power proportion to be 50%; and in a case that the ratio is greater than an upper limit value of the preset ratio range, determining the first preset power proportion and the second preset power proportion as a fifth preset value and a sixth preset value respectively.

[0010] In the embodiment of the present application, the preset ratio range is 0.8-1.2, the first preset value has a value of 60%, the second preset value has a value of 40%, the third preset value has a value of 60%, the fourth preset value has a value of 40%, the fifth preset value has a value of 70%, and the sixth preset value has a value of 30%.

[0011] In the embodiment of the present application, the positive flow excavator further includes an engine, and respectively determining the first control current of the first main pump solenoid valve and the second control current of the second main pump solenoid valve according to the first preset power proportion and the second preset power proportion includes: determining a first required displacement of the first main pump and a second required displacement of the second main pump according to the pilot pressure; obtaining a gear position of the engine, an engine speed, a first pressure of the first main pump and a second pressure of the second main pump; determining first set power of the first main pump and second set power of the second main pump according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure; determining a first output displacement of the first main pump and a second output displacement of the second main pump according to the first set power, the second set power, the engine speed, the first pressure and the second pressure; and respectively determining the first control current and the second control current according to the first output displacement and the second output displacement.

[0012] In the embodiment of the present application, determining the first required displacement of the first main pump and the second required displacement of the second main pump according to the pilot pressure includes: determining the first required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and determining the second required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure.

[0013] In the embodiment of the present application, determining the first required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure includes: respectively determining a left traveling required displacement, a boom raising required displacement, a boom lowering required displacement, a bucket close required displacement, a bucket dump required displacement, an arm in required displacement and an arm out required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and using a maximum value among the left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement as the first required displacement.

[0014] In the embodiment of the present application, determining the second required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure includes: respectively determining a right traveling required displacement, a swing required displacement, a boom raising required displacement, an arm in required displacement and an arm out required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and using a maximum value among the right traveling required displacement, the swing required displacement, the boom raising required displacement, the arm in required displacement and the arm out required displacement as the second required displacement.

[0015] In the embodiment of the present application, determining the first set power of the first main pump and the second set power of the second main pump according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure includes: determining a sum of maximum output power of the first main pump and the second main pump according to the gear position; determining first preset power of the first main pump and second preset power of the second main pump according to the first preset power proportion, the second preset power proportion and the sum of maximum output power; determining first required power of the first main pump and second required power of the second main pump according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure; and determining the first set power and the second set power according to the first preset power, the second preset power, the first required power and the second required power.

[0016] In the embodiment of the present application, determining the first required power of the first main pump and the second required power of the second main pump according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure includes:

determining the first required power according to a formula below:

where power_pilot1 is the first required power, q1 is the first required displacement, n is the engine speed, and p1_press is the first pressure; and

determining the second required power according to a formula below:

where power_pilot2 is the second required power, q2 is the second required displacement, n is the engine speed, and p2_press is the second pressure.

[0017] In the embodiment of the present application, determining the first set power and the second set power according to the first preset power, the second preset power, the first required power and the second required power includes: determining a maximum value in the first preset power and the first required power as the first set power; and determining a maximum value in the second preset power and the second required power as the second set power.

[0018] In the embodiment of the present application, determining the first output displacement of the first main pump and the second output displacement of the second main pump according to the first set power, the second set power, the engine speed, the first pressure and the second pressure includes:

determining the first output displacement according to a formula below:

where q1_set is the first output displacement, power_set1 is the first set power, n is the engine speed, and p1_press is the first pressure; and

determining the second output displacement according to a formula below:

where q2_set is the second output displacement, power_set2 is the second set power, n is the engine speed, and p2_press is the second pressure.

[0019] In the embodiment of the present application, respectively determining the first control current of the first main pump and the second control current of the second main pump according to the first output displacement and the second output displacement includes:

determining the first control current according to a formula below:

where set_current1 is the first control current, q1_set is the first output displacement, q1 min is a non-zero lower limit value of a value range of an output displacement of the first main pump, q1_max is an upper limit value of the value range of the output displacement of the first main pump, c1_min is a non-zero lower limit value of a value range of a control current of the first main pump, and c1_max is an upper limit value of the value range of the control current of the first main pump; and

determining the second control current according to a formula below:

where set_current2 is the second control current, q2_set is the second output displacement, q2_min is a non-zero lower limit value of a value range of an output displacement of the second main pump, q2_max is an upper limit value of the value range of the output displacement of the second main pump, c2_min is a non-zero lower limit value of a value range of a control current of the second main pump, and c2_max is an upper limit value of the value range of the control current of the second main pump.

[0020] A second aspect of the present application provides a controller, configured to execute the control method for the positive flow excavator in the aforementioned embodiment.

[0021] A third aspect of the present application provides a control device for a positive flow excavator, the positive flow excavator including a control mechanism, an engine, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve, and the control device including: an arm in pilot pressure sensor, configured to detect an arm in pilot pressure; an arm out pilot pressure sensor, configured to detect an arm out pilot pressure; a swing pilot pressure sensor, configured to detect a swing pilot pressure; a left traveling pilot pressure sensor, configured to detect a left traveling pilot pressure; a right traveling pilot pressure sensor, configured to detect a right traveling pilot pressure; a boom raising pilot pressure sensor, configured to detect a boom raising pilot pressure; a boom lowering pilot pressure sensor, configured to detect a boom lowering pilot pressure; a bucket close pilot pressure sensor, configured to detect a bucket close pilot pressure; a bucket dump pilot pressure sensor, configured to detect a bucket dump pilot pressure; a first main pump pressure sensor, configured to detect a first pressure of the first main pump; a second main pump pressure sensor, configured to detect a second pressure of the second main pump; an engine controller, configured to provide an engine speed; a throttle knob, configured to provide a gear position of the engine; and the controller in the aforementioned embodiment.

[0022] A fourth aspect of the present application provides a positive flow excavator, including: a control mechanism; an engine; a first main pump; a second main pump; a first main pump solenoid valve; a second main pump solenoid valve; and the control device for the positive flow excavator in the aforementioned embodiment.

[0023] In the aforementioned embodiments of the present application, a method of classifying the action type of the positive flow excavator according to different pilot pressures is provided by collecting the pilot pressure of the control mechanism, power allocation schemes for the dual pumps under different action types are provided, the throttling loss can be effectively avoided, the controllability is ensured, and both the fuel economy and operation efficiency are achieved.

[0024] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description.

Brief Description of Drawings

[0025] The accompanying drawings are intended to provide a further understanding of embodiments of the present application, form a part of the description, and are used to explain the embodiments of the present application together with the following detailed description, but do not constitute a limitation to the embodiments of the present application. In the accompanying drawings:

Fig. 1 is a schematic flow diagram of a control method 100 for a positive flow excavator in an embodiment of the present application.

Fig. 2 is a schematic structural diagram of a control device 200 for a positive flow excavator in an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a positive flow excavator 300 in an embodiment of the present application.

Fig. 4 is a schematic structural diagram of a control system for a positive flow excavator in an example of the present application.

Fig. 5 is a sequence diagram of a judging signal for a composite action of boom raising plus swing in an example of the present application.

Fig. 6 is a sequence diagram of a judging signal for a composite action of arm out plus bucket dump in an example of the present application.

Fig. 7 is a schematic diagram of a relationship between pilot pressures during a raising action performed by an operator operating boom raising and swing simultaneously in an example of the present application.

Fig. 8 is a schematic diagram of a relationship between a pilot pressure and a required displacement corresponding to main pumps during a single action in an example of the present application.

Fig. 9 is a schematic diagram of an overall scheme during introduction of a PID algorithm in an example of the present application.

Fig. 10 is a schematic diagram of a relationship between control currents of main pumps and output displacements of the main pumps in an example of the present application.

Detailed Description of the Embodiments

[0026] The detailed description of embodiments of the present application is described in detail below in combination with the accompanying drawings. It is to be understood that, the detailed description described herein is only used to illustrate and explain the embodiments of the present application instead of limiting the embodiments of the present application.

[0027] It is to be noted that, if directional indications (such as upper, lower, left, right, front, rear...) are involved in implementations of the present application, the directional indications are only used to explain a relative position relationship and motions of components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0028] In addition, if descriptions such as "first" and "second" are involved in the implementations of the present application, the descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of technical features indicated. Therefore, features that are defined by "first" and "second" can explicitly or implicitly include at least one of these features. In addition, technical solutions between various implementations can be combined with each other, but on the basis that they must be implemented by those of ordinary skill in the art. When the combination of the technical solutions is contradictory or impossible to achieve, it should be considered that this combination of the technical solutions does not exist and is not within the scope of protection required by the present application.

[0029] As shown in Fig. 1, in an embodiment of the present application, a control method 100 for a positive flow excavator is provided. The positive flow excavator includes a control mechanism, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve. The control method 100 for the positive flow excavator includes the following steps:

Step S110: obtaining a pilot pressure of the control mechanism. The control mechanism includes, for example, a left joystick, a right joystick, a left traveling pedal and a right traveling pedal. The pilot pressure of the control mechanism may be, for example, obtained through a pilot pressure sensor group including, for example, specifically an arm in pilot pressure sensor, an arm out pilot pressure sensor, a swing pilot pressure sensor, a left traveling pilot pressure sensor, a right traveling pilot pressure sensor, a boom raising pilot pressure sensor, a boom lowering pilot pressure sensor, a bucket close pilot pressure sensor and a bucket dump pilot pressure sensor.

Step S120: determining an action type of the positive flow excavator according to the pilot pressure.

Step S130: determining a first preset power proportion of the first main pump and a second preset power proportion of the second main pump according to the action type, wherein a sum of the first preset power proportion and the second preset power proportion is 100%. The first preset power proportion refers to a proportion of first preset power of the first main pump in a sum of maximum output power of the first main pump and the second main pump. The second preset power proportion refers to a proportion of second preset power of the second main pump in the sum of maximum output power of the first main pump and the second main pump.

Step S140: respectively determining a first control current of the first main pump solenoid valve and a second control current of the second main pump solenoid valve according to the first preset power proportion and the second preset power proportion.

Step S150: respectively outputting the first control current and the second control current to the first main pump solenoid valve and the second main pump solenoid valve, so as to control output power of the first main pump and output power of the second main pump.

[0030] Specifically, the pilot pressure includes, for example: an arm in pilot pressure, an arm out pilot pressure, a swing pilot pressure, a left traveling pilot pressure, a right traveling pilot pressure, a boom raising pilot pressure, a boom lowering pilot pressure, a bucket close pilot pressure and a bucket dump pilot pressure.

[0031] Specifically, the action type may be, for example, selected from any one of the following: a composite action of boom raising plus swing, a composite action of arm out plus bucket dump, and other actions than the composite action of boom raising plus swing and the composite action of arm out plus bucket dump.

[0032] More specifically, step S120 that the action type of the positive flow excavator is determined according to the pilot pressure includes, for example, the following steps:

(a1) in a case that the pilot pressure meets a first condition, it is determined that the action type is the composite action of boom raising plus swing, wherein the first condition includes: both the boom raising pilot pressure and the swing pilot pressure being greater than or equal to a preset opening pressure, and the arm in pilot pressure, the arm out pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure and the bucket dump pilot pressure being all smaller than the preset opening pressure. Specifically, a value range of the preset opening pressure is, for example, 5 bar to 7 bar, such as, specifically, 5 bar, 6 bar, 7 bar and other values.

(a2) In a case that the pilot pressure meets a second condition, it is determined that the action type is the composite action of arm out plus bucket dump, wherein the second condition includes: both the arm out pilot pressure and the bucket dump pilot pressure being greater than or equal to the preset opening pressure, and the boom raising pilot pressure, the swing pilot pressure, the arm in pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure and the bucket close pilot pressure being all smaller than the preset opening pressure.

(a3) In a case that the pilot pressure does not meet any one of the first condition and the second condition, it is determined that the action type is the other actions.

[0033] Step S130 that the first preset power proportion of the first main pump and the second preset power proportion of the second main pump are determined according to the action type includes, for example, the following steps:

(b1) in a case that the action type is the composite action of boom raising plus swing, the first preset power proportion and the second preset power proportion are determined according to a ratio of the boom raising pilot pressure to the swing pilot pressure.

(b2) In a case that the action type is the composite action of arm out plus bucket dump, the first preset power proportion and the second preset power proportion are determined as a first preset value and a second preset value respectively. Specifically, the first preset value may, for example, have any value between 50% and 70%, such as 50%, 56%, 60%, 62% and 70%. Correspondingly, the second preset value may, for example, have any value between 30% and 50%, such as 30%, 35%, 40%, 47% and 50%.

(b3) In a case that the action type is the other actions, both the first preset power proportion and the second preset power proportion are set to be 50%.

[0034] More specifically, step (b1) that in a case that the action type is the composite action of boom raising plus swing, the first preset power proportion and the second preset power proportion are determined according to the ratio of the boom raising pilot pressure to the swing pilot pressure includes, for example, the following steps:

(b11) in a case that the ratio is within a preset ratio range, the first preset power proportion and the second preset power proportion are determined as a third preset value and a fourth preset value respectively. Specifically, a lower limit value of the preset ratio range may, for example, have any value between 0.7 and 0.9, such as 0.7, 0.8 and 0.9, and an upper limit value of the preset ratio range may, for example, have any value between 1.1 and 1.3, such as 1.1, 1.2 and 1.3. Specifically, the lower limit value and the upper limit value of the preset ratio range are, for example, 0.8 and 1.2 respectively, and in this case, the preset ratio range is 0.8-1.2 correspondingly. Specifically, the third preset value may, for example, have any value between 55% and 65%, such as 55%, 58%, 60%, 63% and 65%. Correspondingly, the fourth preset value may, for example, have any value between 35% and 45%, such as 35%, 39%, 40%, 42% and 45%.

(b12) In a case that the ratio is smaller than the lower limit value of the preset ratio range, both the first preset power proportion and the second preset power proportion are set to be 50%.

(b13) In a case that the ratio is greater than the upper limit value of the preset ratio range, the first preset power proportion and the second preset power proportion are determined as a fifth preset value and a sixth preset value respectively. Specifically, the fifth preset value may, for example, have any value between 65% and 75%, such as 65%, 67%, 70%, 72% and 75%. Correspondingly, the sixth preset value may, for example, have any value between 25% and 35%, such as 25%, 28%, 30%, 31% and 35%.

[0035] Further, the positive flow excavator further includes, for example, an engine. Accordingly, step S140 that the first control current of the first main pump solenoid valve and the second control current of the second main pump solenoid valve are respectively determined according to the first preset power proportion and the second preset power proportion includes, for example:

(c1) a first required displacement of the first main pump and a second required displacement of the second main pump are determined according to the pilot pressure.

(c2) A gear position of the engine, an engine speed, a first pressure of the first main pump and a second pressure of the second main pump are obtained. Specifically, the gear position of the engine may be, for example, obtained through a throttle knob of the positive flow excavator; the engine speed may be, for example, obtained through an engine controller; and the first pressure of the first main pump and the second pressure of the second main pump may be, for example, obtained respectively by setting corresponding main pump pressure sensors.

(c3) First set power of the first main pump and second set power of the second main pump are determined according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure.

(c4) A first output displacement of the first main pump and a second output displacement of the second main pump are determined according to the first set power, the second set power, the engine speed, the first pressure and the second pressure.

(c5) The first control current and the second control current are respectively determined according to the first output displacement and the second output displacement.

[0036] Specifically, step (c1) that the first required displacement of the first main pump and the second required displacement of the second main pump are determined according to the pilot pressure includes, for example, the following steps:

(c11) the first required displacement is determined according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and

(c12) the second required displacement is determined according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure.

[0037] Specifically, step (c11) that the first required displacement is determined according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure includes, for example, the following steps:

(c111) a left traveling required displacement, a boom raising required displacement, a boom lowering required displacement, a bucket close required displacement, a bucket dump required displacement, an arm in required displacement and an arm out required displacement are respectively determined according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure. The left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement respectively refer to required displacements corresponding to the first main pump in a case of corresponding single actions, namely in a case of a left traveling single action, a boom raising single action, a boom lowering single action, a bucket close single action, a bucket dump single action, an arm in single action and an arm out single action respectively.

(c112) A maximum value among the left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement is used as the first required displacement. That is, after the required displacements corresponding to the first main pump in the case of the left traveling single action, the boom raising single action, the boom lowering single action, the bucket close single action, the bucket dump single action, the arm in single action and the arm out single action are calculated, a required displacement with a maximum value therein is used as the required displacement, namely the first required displacement, corresponding to the first main pump in a case of any action among left traveling, boom raising, boom lowering, bucket close (i.e. closing the bucket), bucket dump(i.e. dumping the bucket), arm in(i.e. moving the arm inward) and arm out(i.e. moving the arm outward), or various possible single actions or composite actions composed of a plurality of random actions. That is to say, regardless of whether it is the single action or composite action among left traveling, boom raising, boom lowering, bucket close, bucket dump, arm in and arm out actually, the maximum value among the left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement is used as the required displacement, namely the first required displacement, corresponding to the first main pump.

[0038] Specifically, step (c12) that the second required displacement is determined according to the right traveling pilot pressure, the swingswing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure includes, for example, the following steps:

(c121) a right traveling required displacement, a swing required displacement, a boom raising required displacement, an arm in required displacement and an arm out required displacement are respectively determined according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure. Similarly, the right traveling required displacement, the swing required displacement, the boom raising required displacement, the arm in required displacement and the arm out required displacement respectively refer to required displacements corresponding to the second main pump in a case of corresponding single actions, namely in a case of a right traveling single action, a swing single action, a boom raising single action, an arm in single action and an arm out single action respectively.

(c122) A maximum value among the right traveling required displacement, the swing required displacement, the boom raising required displacement, the arm in required displacement and the arm out required displacement is used as the second required displacement. That is, after the required displacements corresponding to the second main pump in the case of the right traveling single action, the swing single action, the boom raising single action, the arm in single action and the arm out single action are calculated, a required displacement with a maximum value therein is used as the required displacement, namely the second required displacement, corresponding to the second main pump.

[0039] Specifically, a determining formula for determining the left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement which are required by the first required displacement, and for determining the right traveling required displacement, the swing required displacement, the boom raising required displacement, the arm in required displacement and the arm out required displacement which are required by the second required displacement is, for example:

where qi_n is a required displacement corresponding to an i^th main pump in a case of an n^th single action, gi_min is a non-zero lower limit value of a value range of the output displacement of the i^th main pump, pilot_n is a pilot pressure corresponding to the n^th single action, pilot_n_min is a minimum secondary pressure needed when a valve element corresponding to the n^th single action is opened, pilot_n_max is a minimum secondary pressure needed when the valve element corresponding to the n^th single action is fully opened, and qi_max is an upper limit value of the value range of the output displacement of the i^th main pump.

[0040] Specifically, for example, when the left traveling required displacement required by the first required displacement of the first main pump is determined, in the above formula, qi_n is a required displacement corresponding to the first main pump in a case of the left traveling single action; qi_min is a non-zero lower limit value of a value range of the output displacement of the first main pump; pilot_n is a pilot pressure corresponding to the left traveling single action, namely the left traveling pilot pressure; pilot_n_min is a minimum secondary pressure needed when a left traveling valve element corresponding to the left traveling single action is opened; pilot_n_max is a minimum secondary pressure needed when the left traveling valve element corresponding to the left traveling single action is fully opened; and qi_max is an upper limit value of the value range of the output displacement of the first main pump. A principle for determining required displacements of other actions is the same, which is omitted here.

[0041] Specifically, step (c3) that the first set power of the first main pump and the second set power of the second main pump are determined according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure includes, for example, the following steps:

(c31) a sum of maximum output power of the first main pump and the second main pump is determined according to the gear position. In a case that the gear position is determined, the sum of maximum output power of the first main pump and the second main pump may be determined according to a dual-pump total power value of the positive flow excavator, namely a correspondence relationship between the sum of maximum output power of the first main pump and the second main pump and the gear position.

(c32) First preset power of the first main pump and second preset power of the second main pump are determined according to the first preset power proportion, the second preset power proportion and the sum of maximum output power. Specifically, for example, the first preset power may be obtained by multiplying the first preset power proportion by the sum of maximum output power, and the second preset power may be obtained by multiplying the second preset power proportion by the sum of maximum output power.

(c33) First required power of the first main pump and second required power of the second main pump are determined according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure.

(c34) The first set power and the second set power are determined according to the first preset power, the second preset power, the first required power and the second required power.

[0042] Specifically, step (c33) that the first required power of the first main pump and the second required power of the second main pump are determined according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure includes, for example:

(c331) the first required power is determined according to a formula below:

where power _pilot1 is the first required power, q1 is the first required displacement, n is the engine speed, and p1_press is the first pressure.

(c332) The second required power is determined according to a formula below:

where power_pilot2 is the second required power, q2 is the second required displacement, n is the engine speed, and p2_press is the second pressure.

[0043] Specifically, step (c34) that the first set power and the second set power are determined according to the first preset power, the second preset power, the first required power and the second required power includes, for example:

(c341) a maximum value in the first preset power and the first required power is determined as the first set power; and

(c342) a maximum value in the second preset power and the second required power is determined as the second set power.

[0044] More specifically, step (c4) that the first output displacement of the first main pump and the second output displacement of the second main pump are determined according to the first set power, the second set power, the engine speed, the first pressure and the second pressure includes, for example:

(c41) the first output displacement is determined according to a formula below:

where q1_set is the first output displacement, power _set1 is the first set power, n is the engine speed, and p1_press is the first pressure.

(c42) The second output displacement is determined according to a formula below:

where q2_set is the second output displacement, power_set2 is the second set power, n is the engine speed speed, and p2_press is the second pressure.

[0045] Specifically, step (c5) that the first control current and the second control current are respectively determined according to the first output displacement and the second output displacement includes, for example:

(c51) the first control current is determined according to a formula below:

where set_current1 is the first control current, q1_set is the first output displacement, q1 min is a non-zero lower limit value of the value range of the output displacement of the first main pump, q1_max is an upper limit value of the value range of the output displacement of the first main pump, c1_min is a non-zero lower limit value of a value range of a control current of the first main pump, and c1_max is an upper limit value of the value range of the control current of the first main pump.

(c52) The second control current is determined according to a formula below:

where set_current2 is the second control current, q2_set is the second output displacement, q2_min is a non-zero lower limit value of a value range of an output displacement of the second main pump, q2_max is an upper limit value of the value range of the output displacement of the second main pump, c2_min is a non-zero lower limit value of a value range of a control current of the second main pump, and c2_max is an upper limit value of the value range of the control current of the second main pump.

[0046] Specifically, a value range of the non-zero lower limit value of the value range of the output displacement of the first main pump and a value range of the non-zero lower limit value of the value range of the output displacement of the second main pump are both, for example, 5 L/min to 10 L/min. A value range of the upper limit value of the value range of the output displacement of the first main pump and a value range of the upper limit value of the value range of the output displacement of the second main pump are both, for example, 120 L/min to 140 L/min. The non-zero lower limit value of the value range of the control current of the first main pump and the non-zero lower limit value of the value range of the control current of the second main pump both have a value range such as 300 mA to 400 mA. The upper limit value of the value range of the control current of the first main pump and the upper limit value of the value range of the control current of the second main pump both have a value range such as 700 mA to 800 mA.

[0047] In an embodiment of the present application, a controller is provided. The controller is configured to, for example, execute the control method 100 for the positive flow excavator according to any aforementioned embodiment.

[0048] For specific functions and details about the control method 100 for the positive flow excavator, reference may be made to relevant descriptions of the aforementioned embodiments, which are omitted here.

[0049] Specifically, the controller may be, for example, control apparatuses such as an industrial personal computer, an embedded system, a microprocessor and a programmable logic device.

[0050] More specifically, the controller is, for example, a machine control unit of the positive flow excavator.

[0051] As shown in Fig. 2, in an embodiment of the present application, a control device 200 for a positive flow excavator is provided. The positive flow excavator includes a control mechanism, an engine, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve. The control device 200 for the positive flow excavator includes: a controller 201, an arm in pilot pressure sensor 202, an arm out pilot pressure sensor 203, a swing pilot pressure sensor 204, a left traveling pilot pressure sensor 205, a right traveling pilot pressure sensor 206, a boom raising pilot pressure sensor 207, a boom lowering pilot pressure sensor 208, a bucket close pilot pressure sensor 209, a bucket dump pilot pressure sensor 210, a first main pump pressure sensor 211, a second main pump pressure sensor 212, an engine controller 213, and a throttle knob 214.

[0052] The controller 201 is, for example, the controller according to any aforementioned embodiment. For specific functions and details about the controller 201, reference may be made to relevant descriptions of the aforementioned embodiments, which are omitted here.

[0053] The arm in pilot pressure sensor 202 is configured to, for example, detect an arm in pilot pressure.

[0054] The arm out pilot pressure sensor 203 is configured to, for example, detect an arm out pilot pressure.

[0055] The swing pilot pressure sensor 204 is configured to, for example, detect a swing pilot pressure.

[0056] The left traveling pilot pressure sensor 205 is configured to, for example, detect a left traveling pilot pressure.

[0057] The right traveling pilot pressure sensor 206 is configured to, for example, detect a right traveling pilot pressure.

[0058] The boom raising pilot pressure sensor 207 is configured to, for example, detect a boom raising pilot pressure.

[0059] The boom lowering pilot pressure sensor 208 is configured to, for example, detect a boom lowering pilot pressure.

[0060] The bucket close pilot pressure sensor 209 is configured to, for example, detect a bucket close pilot pressure.

[0061] The bucket dump pilot pressure sensor 210 is configured to, for example, detect a bucket dump pilot pressure.

[0062] The first main pump pressure sensor 211 is configured to, for example, detect a first pressure of the first main pump.

[0063] The second main pump pressure sensor 212 is configured to, for example, detect a second pressure of the second main pump.

[0064] The engine controller 213 is configured to, for example, provide an engine speed.

[0065] The throttle knob 214 is configured to, for example, provide a gear position of the engine.

[0066] In an embodiment of the present application, a positive flow excavator 300 is provided, including: a control device 310, a control mechanism 320, an engine 330, a first main pump 340, a second main pump 350, a first main pump solenoid valve 360, and a second main pump solenoid valve 370.

[0067] The control device 310 is, for example, the control device 200 for the positive flow excavator according to any aforementioned embodiment. For specific functions and details about the control device 310, reference may be made to relevant descriptions of the aforementioned embodiments, which are omitted here.

[0068] The control method 100 for the positive flow excavator, the control device 200 for the positive flow excavator and the positive flow excavator 300 in the embodiments of the present application are described in detail below in combination with a specific example, and the example of the present application has the following specific contents.

[0069] As shown in Fig. 4, it is a control system for a positive flow excavator provided by the example of the present application. The control system mainly includes a left joystick 101, a left traveling pedal 102, a right traveling pedal 103, a rightjoystick 104, a pilot pressure sensor group 2000 (an arm in pilot pressure sensor 2000-1, an arm out pilot pressure sensor 2000-2, a swing pilot pressure sensor 2000-3, a left traveling pilot pressure sensor 2000-4, a right traveling pilot pressure sensor 2000-5, a boom raising pilot pressure sensor 2000-6, a boom lowering pilot pressure sensor 2000-7, a bucket close pilot pressure sensor 2000-8, and a bucket dump pilot pressure sensor 2000-9), a main pump pressure sensor 201, a main pump pressure sensor 202, a main pump solenoid valve 203, a main pump solenoid valve 204, a main pump 205, a main pump 206, a main control valve group 300, a boom oil cylinder 301, an arm oil cylinder 302, a bucket oil cylinder 303, a swing motor 304, a display 401, a controller 402, an engine controller 403 and an engine 404.

[0070] In order to consider both operation efficiency and fuel economy of the excavator, in the example of the present application, the use of logic valves such as a boom-to-arm limit valve and an arm priority over bucket valve which are commonly used in the prior art is canceled, a pilot pressure of a control mechanism (including the left joystick 101, the left traveling pedal 102, the right traveling pedal 103 and the right joystick 104) as well as pressures of the main pumps 205 and 206 are collected through the controller 402, a method for classified identification of an action type of the positive flow excavator according to different pilot pressures is provided, power allocation schemes for the dual pumps under different action types are provided, the throttling loss can be effectively avoided, the controllability is ensured, and both the fuel economy and operation efficiency are achieved.

[0071] The example of the present application focuses on solving the issues of fuel efficiency and controllability during digging and loading operations of the positive flow excavator. One operation cycle of an excavator loading action mainly has four stages below:

(1) a composite action of arm in plus bucket close, namely a digging stage;

(2) a composite action of boom raising plus swing, namely a raising stage;

(3) a composite action of arm out plus bucket dump, namely an dumping stage;

(4) a composite action of boom lowering plus arm in, namely a return stage.

[0072] The main contents of the control system for the positive flow excavator in the example of the present application are described below in combination with the accompanying drawings.

I. Action identification

[0073] A signal, namely a pilot pressure, of the pilot pressure sensor group 2000 is collected through the controller 402, and whether a current action type is the composite action of boom raising plus swing, the composite action of arm out plus bucket dump or other actions than the two aforementioned actions (namely the composite action of boom raising plus swing and the composite action of arm out plus bucket dump) is identified respectively.

(1) The composite action of boom raising plus swing, namely the raising stage.
Fig. 5 shows a sequence diagram of a judging signal for the composite action of boom raising plus swing in the example of the present application. The signal, namely the pilot pressure, of the pilot pressure sensor group 2000 is collected through the controller 402. Typically, a value range of respective pilot pressures is 0 bar to 40 bar; a value range of a minimum secondary pressure needed for opening respective valve elements is 5 bar to 7 bar, such as, specifically, 5 bar; and respective pilot pressures are all 0 when there is no action, namely the corresponding joysticks or pedals are not controlled. Therefore, when a boom raising pilot pressure is greater than or equal to 5 bar, a swing pilot pressure is greater than or equal to 5 bar, and other 7 pilot pressures (namely an arm in pilot pressure, an arm out pilot pressure, a left traveling pilot pressure, a right traveling pilot pressure, a boom lowering pilot pressure, a bucket close pilot pressure and a bucket dump pilot pressure) are all smaller than 5 bar, the controller 402 determines the current action type of the positive flow excavator as the composite action of boom raising plus swing.

(2) The composite action of arm out plus bucket dump, namely the dumping stage.
Fig. 6 shows a sequence diagram of a judging signal for the composite action of arm out plus bucket dump in the example of the present application. The signal, namely the pilot pressure, of the pilot pressure sensor group 2000 is collected through the controller 402. When the arm out pilot pressure is greater than or equal to 5 bar, the bucket dump pilot pressure is greater than or equal to 5 bar, and other 7 pilot pressures (namely the boom raising pilot pressure, the swing pilot pressure, the arm in pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure and the bucket close pilot pressure) are all smaller than 5 bar, the controller 402 determines the current action type of the positive flow excavator as the composite action of arm out plus bucket dump.

(3) Other actions.
When signal logic of the composite action of boom raising plus swing and signal logic of the composite action of arm out plus bucket dump are not met, the controller 402 determines the current action type of the positive flow excavator as other actions, that is, it is determined as the other actions as long as neither the signal logic of the composite action of boom raising plus swing nor the signal logic of the composite action of arm out plus bucket dump is met.

II. Preset power allocation.

1. The composite action of boom raising plus swing, namely the raising stage.

[0074] As shown in Fig. 7, an operator operates boom raising and swing simultaneously for performing a raising action, and in combination with properties of loading actions (90° loading, 180° loading, etc.), the operator typically controls an opening degree of a joystick corresponding to boom raising or swing to achieve the coordination of the actions. In Fig. 7, abscissas and ordinates represent time and corresponding pilot pressures respectively. To reasonably allocate flow, in the prior art, a swingboom priority over swing logic valve is usually added to allocate the flow, thereby guaranteeing the coordination of the boom action and swing action.

[0075] As shown in Fig. 4, the boom oil cylinder 301 is supplied with oil by the main pump 205 and the main pump 206 at the same time, and the swing motor is supplied with oil only by the main pump 206. In the example of the present application, the swingboom priority over swing logic valve is omitted, and different power allocation at different loading angles is achieved by analyzing a proportional relation between the boom raising pilot pressure and the swing pilot pressure, so as to reasonably allocate the flow, which further achieves the coordination of the actions.

[0076] To guarantee a speed of boom raising, first, in the example of the present application, an average allocation scheme of 50% for power of each of dual pumps in the prior art is changed, when the composite action of boom raising plus swing is detected, a preset power proportion of the main pump 205 is set to be η1, and to guarantee that the dual pumps absorb all the power completely, a preset power proportion of the main pump 206 is set to be η2=1-η1.

[0077] Meanwhile, in order to dynamically adjust power allocation of the dual pumps, the controller 402 analyzes a ratio of the boom raising pilot pressure to the swing pilot pressure in real time.

(1) When the ratio ε of the boom raising pilot pressure to the swing pilot pressure is within 0.8-1.2, the preset power proportion η1 of the main pump 205 is set to be 60%, and the preset power proportion η2 of the main pump 206 is set to be 40%, so that it is guaranteed that more hydraulic oil flows to the boom oil cylinder from the main pump 205 via a boom valve element 1, thereby guaranteeing the speed of boom raising.

(2) When the ratio ε of the boom raising pilot pressure to the swing pilot pressure is smaller than 0.8, it denotes that a loading angle is large and the requirement for the speed of boom raising is low, the preset power proportion η1 of the main pump 205 is set to be 50%, and the preset power proportion η2 of the main pump 206 is set to be 50%, so that it is guaranteed that more hydraulic oil flows to the swing motor from the main pump 206 via a swing valve element.
The example of the present application is not limited to this. For example, when the ratio ε is within 0.5-0.8, a value of the preset power proportion η1 of the main pump 205 is 50%-60% correspondingly, that is, when the ratio ε is increased from 0.5 to 0.8, the preset power proportion η1 of the main pump 205 is linearly increased to 60% from 50%. That is, when the ratio ε has a value of 0.5, the value of η1 is 50%, and a value of η2 is 50%. When the ratio ε has a value of 0.8, the value of η1 is 60%, and the value of η2 is 40%. That is, the smaller the ratio ε, the smaller η1, the larger η2, and the more hydraulic oil flowing to the swingswing motor from the main pump 206. When the ratio ε is smaller than 0.5, the values of η1 and η2 are both set to be 50%.

(3) When the ratio ε of the boom raising pilot pressure to the swing pilot pressure is greater than 1.2, it denotes that a swing angle is small and the requirement for boom raising is high, the preset power proportion η1 of the main pump 205 is set to be 70%, and the preset power proportion η2 of the main pump 206 is set to be 30%, so that it is guaranteed that more hydraulic oil flows to the boom oil cylinder from the main pump 206 via the boom valve element 1, thereby guaranteeing the speed of boom raising.

[0078] The example of the present application is not limited to this. For example, when the ratio ε is within 1.2-2, the value of the preset power proportion η1 of the main pump 205 is 60%-70% correspondingly, that is, when the ratio ε is increased from 1.2 to 2, the preset power proportion η1 of the main pump 205 is linearly increased to 70% from 60%. That is, when the ratio ε has a value of 1.2, the value of η1 is 60%, and the value of η2 is 40%. When the ratio ε has a value of 2, the value of η1 is 70%, and the value of η2 is 30%. That is, the larger the ratio ε, the larger η1, the smaller η2, and the more hydraulic oil flowing to the boom oil cylinder from the main pump 205. When the ratio ε is greater than 2, the value of η1 is 70%, and the value of η2 is 30%.

2. The composite action of arm out plus bucket dump, namely the dumping stage.

[0079] The operator operates arm out plus bucket dump at the same time for performing an dumping action. As shown in Fig. 4, hydraulic oil of the main pump 205 flows to the bucket oil cylinder via a bucket valve element to achieve bucket dump, and the hydraulic oil of the main pump 205 and hydraulic oil of the main pump 206 flow to the arm oil cylinder via an arm valve element 2 and an arm valve element 1 respectively to achieve an arm out action. In the prior art, in order to guarantee the coordination of the actions, a bucket priority over arm logic valve is usually arranged, and defects brought by the operating principle are similar to those in the composite action of boom raising plus swing, which are omitted here.

[0080] In the example of the present application, in order to guarantee the coordination of the composite action of arm out plus bucket dump, the bucket priority over arm logic valve is omitted, and in the composite action of arm out plus bucket dump, namely the dumping stage, the preset power proportion η1 of the main pump 205 is set to be 60%, and the preset power proportion η2 of the main pump 206 is set to be 40%, so that it is guaranteed that more hydraulic oil flows to the bucket oil cylinder from the main pump 205 via the bucket valve element, thereby guaranteeing a speed of bucket dump.

(3) Other actions.

[0081] To guarantee the system stability, except the raising stage and the dumping stage, the preset power proportions η1 and η2 of power of the dual pumps are both set to be 50%.

[0082] The example of the present application is not limited to this. Further, to guarantee the system stability, the controller 402 detects signals of the main pump pressure sensor 201 and the main pump pressure sensor 202 to obtain a pressure of the main pump 205 and a pressure of the main pump 206, and when the pressure of any main pump is greater than a preset pressure such as any value between 30 Mpa and 35 Mpa, such as 34 Mpa, the controller 402 determines that a current stage of the positive flow excavator is an overflow state, so regardless of the action type of the positive flow excavator at the moment, the preset power proportions η1 and η2 of the power of the dual pumps are both set to be 50%.

III. Calculation of required displacement.

1. Calculation of a required displacement corresponding to a certain main pump during a single action.

[0083] As shown in Fig. 8, when a pilot pressure corresponding to a certain action is smaller than or equal to a minimum secondary pressure pilot_min (a value range of 5 bar to 7 bar) needed when a corresponding valve element is opened, a required displacement of the main pump corresponding to the action is set to be a non-zero lower limit value q_Min of a value range of an output displacement of this main pump. When the pilot pressure corresponding to this action is greater than or equal to a minimum secondary pressure pilot_max (a value range of 20 bar to 25 bar) needed when the corresponding valve element is fully opened, the required displacement of the main pump corresponding to this action is set to be an upper limit value q_Max of the value range of the output displacement of this main pump. When the pilot pressure corresponding to this action is greater than pilot_min and smaller than pilot_max, the required displacement corresponding to this action is obtained through linear calculation, that is, when the pilot pressure corresponding to this action is increased from pilot_min to pilot_max, the required displacement of the main pump corresponding to this action is linearly increased from q_Min to q_Max.

[0084] In the example of the present application, the main pump 205 and the main pump 206 typically use main pumps of the same performance, thus, the output displacements of the main pump 205 and the main pump 206 have the same value range, and therefore, the value ranges of the output displacements have the same non-zero lower limit value q_Min and the same upper limit value q_Max. The value range of q_Min is, for example, 5 L/min to 10 L/min. The value range of q_Max is, for example, 120 L/min to 140 L/min, and in the example of the present application, q_Min and q_ Max are not limited to the exemplary value ranges given here, and specific value ranges and values are related to the models of the main pumps.

2. Calculation of a required displacement q1 of the main pump 205 during a composite action.

[0085] The required displacement of the main pump 205 is determined by the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure. During a composition action, required displacements of the main pump 205 corresponding to respective single actions, which determine the required displacement of the main pump 205, are calculated first according to the aforementioned method for calculating the required displacement corresponding to a certain main pump during a single action, and then the required displacement q1 of the main pump 205 during the composite action is calculated according to a preset function f(x). In the example of the present application, f(x) performs calculation, for example, by directly taking a maximum value, that is, a maximum value among the required displacements corresponding to all the single actions which determine the required displacement of the main pump 205 is used as the required displacement q1 of the main pump 205 during the composite action.

[0086] In the example of the present application, no matter whether the positive flow excavator executes a single action or a composite action actually, it is regarded as the composite action, and q1 is calculated according to the method for calculating the required displacement q1 of the main pump 205 during the composite action, that is, the required displacements of the main pump 205 corresponding to respective single actions, which determine the required displacement of the main pump 205, are calculated according to the aforementioned method for calculating the required displacement corresponding to a certain main pump during a single action, and then the maximum value among the required displacements corresponding to all the single actions which determine the required displacement of the main pump 205 is used as the required displacement q1 of the main pump 205 during the composite action.

3. Calculation of a required displacement q2 of the main pump 206 during a composite action.

[0087] The required displacement of the main pump 206 is determined by the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure, and a calculation method is the same as the calculation method for the required displacement q1 of the main pump 205 during a composite action. That is, required displacements of the main pump 206 corresponding to respective single actions, which determine the required displacement of the main pump 206, are calculated first according to the aforementioned method for calculating the required displacement corresponding to a certain main pump during a single action, and then a maximum value among the required displacements corresponding to all the single actions which determine the required displacement of the main pump 206 is used as the required displacement q2 of the main pump 206 during the composite action.

[0088] Similarly, in the example of the present application, no matter whether the positive flow excavator executes a single action or a composite action actually, it is regarded as the composite action, and q2 is calculated according to the method for calculating the required displacement q2 of the main pump 206 during the composite action, that is, the required displacements of the main pump 206 corresponding to respective single actions, which determine the required displacement of the main pump 206, are calculated according to the aforementioned method for calculating the required displacement corresponding to a certain main pump during a single action, and then the maximum value among the required displacements corresponding to all the single actions which determine the required displacement of the main pump 206 is used as the required displacement q2 of the main pump 206 during the composite action.

IV. Power calculation.

[0089] 

1. A total power value of dual pumps is preset in a system.
The total power value of the dual pumps is set by the controller 402 according to different engine gear positions and engine speeds, namely a sum of maximum output power of the first main pump and the second main pump, and when the engine works at a certain gear position, the total power value of the dual pumps, namely the main pump 205 and the main pump 206, is Power_Default.

2. In combination with the preset power proportion η1 of the main pump 205 and the preset power proportion η2 of the main pump 206 determined in the aforementioned section of preset power allocation, preset power of each main pump is calculated.

The preset power of the main pump 205 is Power_Default1=Power_Default*η1.

The preset power of the main pump 206 is Power_Default2=Power_Default*η2.

3. Calculation of required power Power_Pilot.

Required power of the main pump 205:

.

Required power of the main pump 206:

.

where, n is the engine speed, P1_Press is the pressure of the main pump 205, P2_Press is the pressure of the main pump 206, q1 is the required displacement of the main pump 205, and q2 is the required displacement of the main pump 206.

4. Power setting.

The set power of the main pump 205 is a smaller value in the required power Power_Pilot1 of the main pump 205 and the preset power Power_Default1 of the main pump 205, that is:
the set power of the main pump 205 is Power_Set1=min(Power_Pilot1,Power_Default1).

The set power of the main pump 206 is a smaller value in the required power Power _Pilot2 of the main pump 206 and the preset power Power_Default2 of the main pump 206, that is:
the set power of the main pump 206 is Power_Pilot2,Power_Default2).

The example of the present application is not limited to this. As shown in Fig. 9, for example, a PID algorithm may further be introduced to achieve closed-loop control over the set power of the main pump 205 and the main pump 206. The PID algorithm includes, for example, the following main contents:

a calculation method is as follows: δ = Kp* (e(t) - e(t-1)) + Ki* e(t).

[0090] A target engine speed is a target value in PID control, an actual engine speed is an actual value in PID control, and an output variable is a set power percentage δ. A value range of δ is 60%-100%, and an initial value of δ is 100%.

[0091] e(t) is a deviation value between an actual engine speed at a current moment and the target engine speed, and an initial value of e(t) is 0.

[0092] e(t-1) is a deviation value between an actual engine speed at a previous moment and the target engine speed.

[0093] Kp is a calculation proportion coefficient, with a value of -0.1 to -10.

[0094] Ki is a calculation integration coefficient, with a value of -0.1 to -10.

[0095] When e(t)>0 denotes that the actual engine speed at the current moment is higher than the target engine speed, the set power percentage δ shall be increased.

[0096] When e(t)<0 denotes that the actual engine speed at the current moment is lower than the target engine speed, the set power percentage δ shall be decreased.

[0097] The controller 402 conducts automatic adjustment according to the above PID algorithm until the deviation between the actual engine speed and the target engine speed is smaller than a preset value such as 20 rpm, then it is considered that adjustment achieves the purpose, and at the moment, final set power of the two main pumps is further adjusted to be:

the set power of the main pump 205 is Power_Set1=min(Power_Pilot1,Power_Default1)*δ.

the set power of the main pump 206 is Power_Set2=min(Power Pilot2,Power _Default2)*δ.

[0098] Of course, power setting in the example of the present application can achieve the technical effects to be achieved by the example of the present application without introducing the above PID control.

V. Setting of output displacements and control currents.

1. Calculation of output displacements.

[0099] Output displacement of the main pump 205:

.

[0100] Output displacement of the main pump 206:

. where, n is the engine speed, P1_Press is the pressure of the main pump 205, P2_Press is the pressure of the main pump 206, Power_Set1 is the set power of the main pump 205, and Power_Set2 is the set power of the main pump 206.

2. Calculation of control currents.

[0101] As shown in Fig. 10, the control current of the main pump 205:

[0102] The control current of the main pump 206:

[0103] q1_Set is the output displacement of the main pump 205, q2_Set is the output displacement of the main pump 206, q_Min is a non-zero lower limit value of a value range of the output displacement of each main pump, and q_Max is an upper limit value of the value range of the output displacement of each main pump.

[0104] In conclusion, in the embodiments of the present application, by means of the aforementioned technical solutions, the method of classifying the action type of the positive flow excavator according to different pilot pressures is provided by collecting the pilot pressure of the control mechanism, power allocation schemes for the dual pumps under different action types are provided, the throttling loss can be effectively avoided, the controllability is ensured, and both the fuel economy and operation efficiency are achieved.

[0105] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a full hardware embodiment, a full software embodiment, or an embodiment combining software and hardware. Besides, the present application may adopt the form of a computer program product implemented on one or more computer available storage media (including but not limited to a disk memory, a CD-ROM, an optical memory and the like) containing computer available program codes.

[0106] The present application is described with reference to the flow diagram and/or block diagram of the method, apparatus (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and/or block in the flow diagram and/or block diagram and the combination of flows and/or blocks in the flow diagram and/or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to processors of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing apparatuses to generate a machine, so that instructions executed by processors of a computer or other programmable data processing apparatuses generate a device for implementing the functions specified in one or more flows of the flow diagram and/or one or more blocks of the block diagram.

[0107] These computer program instructions can also be stored in a computer-readable memory capable of guiding a computer or other programmable data processing apparatuses to work in a specific manner, so that instructions stored in the computer-readable memory generate a manufacturing product including an instruction device, and the instruction device implements the functions specified in one or more flows of the flow diagram and/or one or more blocks of the block diagram.

[0108] These computer program instructions can also be loaded on a computer or other programmable data processing apparatuses, so that a series of operation steps are executed on the computer or other programmable apparatuses to produce computer-implemented processing, and thus, the instructions executed on the computer or other programmable apparatuses provide steps for implementing the functions specified in one or more flows of the flow diagram and/or one or more blocks of the block diagram.

[0109] In a typical configuration, a computing apparatus includes one or more processors (CPU), an input/output interface, a network interface and a memory.

[0110] The memory may include a volatile memory, a random access memory (RAM) and/or a non-volatile memory and other forms in a computer readable medium, such as a read-only memory (ROM) or a flash RAM. The memory is an example of the computer-readable medium.

[0111] The computer-readable medium includes permanent and non-permanent, and removable and non-removable media, and may achieve information storage through any method or technology. The information may be computer-readable instructions, data structures, modules of programs, or other data. Examples of the computer storage medium include, but are not limited to, a phase-change random access memory (PRAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), other types of random access memories (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory or other memory technologies, a compact disc read-only memory (CD-ROM), a digital versatile disc (DVD) or other optical storage and magnetic cassette tape, magnetic-tape magnetic-disk storage or other magnetic storage devices or any other non-transmission media, and may be used to store information that can be accessed by a computing apparatus. According to the definition herein, the computer-readable medium does not include transitory media, such as modulated data signals and carriers.

[0112] It should further be noted that, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements not only includes those elements, but also includes other elements not clearly listed, or also includes elements inherent to this process, method, article or apparatus. Without further restrictions, the elements defined by the sentence "including a..." do not exclude that there are other same elements in the process, method, article or apparatus including the elements.

[0113] The above is merely the embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall fall within the scope of the claims of the present application.

Claims

1. A control method for a positive flow excavator, the positive flow excavator comprising a control mechanism, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve;
the control method comprising:

obtaining a pilot pressure of the control mechanism;

determining an action type of the positive flow excavator according to the pilot pressure;

determining a first preset power proportion of the first main pump and a second preset power proportion of the second main pump according to the action type, wherein a sum of the first preset power proportion and the second preset power proportion is 100%;

respectively determining a first control current of the first main pump solenoid valve and a second control current of the second main pump solenoid valve according to the first preset power proportion and the second preset power proportion; and

respectively outputting the first control current and the second control current to the first main pump solenoid valve and the second main pump solenoid valve, so as to control output power of the first main pump and output power of the second main pump.

2. The control method according to claim 1, wherein the pilot pressure comprises: an arm in pilot pressure, an arm out pilot pressure, a swing pilot pressure, a left traveling pilot pressure, a right traveling pilot pressure, a boom raising pilot pressure, a boom lowering pilot pressure, a bucket close pilot pressure and a bucket dump pilot pressure; and
the action type is selected from any one of the following:

a composite action of boom raising plus swing;

a composite action of arm out plus bucket dump; and

other actions than the composite action of boom raising plus swing and the composite action of arm out plus bucket dump.

3. The control method according to claim 2, wherein determining the action type of the positive flow excavator according to the pilot pressure comprises:

in a case that the pilot pressure meets a first condition, determining that the action type is the composite action of boom raising plus swing, wherein the first condition comprises: both the boom raising pilot pressure and the swing pilot pressure being greater than or equal to a preset opening pressure, and the arm in pilot pressure, the arm out pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure and the bucket dump pilot pressure being all smaller than the preset opening pressure;

in a case that the pilot pressure meets a second condition, determining that the action type is the composite action of arm out plus bucket dump, wherein the second condition comprises: both the arm out pilot pressure and the bucket dump pilot pressure being greater than or equal to the preset opening pressure, and the boom raising pilot pressure, the swing pilot pressure, the arm in pilot pressure, the left traveling pilot pressure, the right traveling pilot pressure, the boom lowering pilot pressure and the bucket close pilot pressure being all smaller than the preset opening pressure; and

in a case that the pilot pressure does not meet any one of the first condition and the second condition, determining that the action type is the other actions.

4. The control method according to claim 2, wherein determining the first preset power proportion of the first main pump and the second preset power proportion of the second main pump according to the action type comprises:

in a case that the action type is the composite action of boom raising plus swing, determining the first preset power proportion and the second preset power proportion according to a ratio of the boom raising pilot pressure to the swing pilot pressure;

in a case that the action type is the composite action of arm out plus bucket dump, determining the first preset power proportion and the second preset power proportion as a first preset value and a second preset value respectively; and

in a case that the action type is the other actions, setting both the first preset power proportion and the second preset power proportion to be 50%.

5. The control method according to claim 4, wherein determining the first preset power proportion and the second preset power proportion according to the ratio of the boom raising pilot pressure to the swing pilot pressure comprises:

in a case that the ratio is within a preset ratio range, determining the first preset power proportion and the second preset power proportion as a third preset value and a fourth preset value respectively;

in a case that the ratio is smaller than a lower limit value of the preset ratio range, setting both the first preset power proportion and the second preset power proportion to be 50%; and

in a case that the ratio is greater than an upper limit value of the preset ratio range, determining the first preset power proportion and the second preset power proportion as a fifth preset value and a sixth preset value respectively.

6. The control method according to claim 5, wherein the preset ratio range is 0.8-1.2, the first preset value has a value of 60%, the second preset value has a value of 40%, the third preset value has a value of 60%, the fourth preset value has a value of 40%, the fifth preset value has a value of 70%, and the sixth preset value has a value of 30%.

7. The control method according to claim 2, wherein the positive flow excavator further comprises an engine, and respectively determining the first control current of the first main pump solenoid valve and the second control current of the second main pump solenoid valve according to the first preset power proportion and the second preset power proportion comprises:

determining a first required displacement of the first main pump and a second required displacement of the second main pump according to the pilot pressure;

obtaining a gear position of the engine, an engine speed, a first pressure of the first main pump and a second pressure of the second main pump;

determining first set power of the first main pump and second set power of the second main pump according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure;

determining a first output displacement of the first main pump and a second output displacement of the second main pump according to the first set power, the second set power, the engine speed, the first pressure and the second pressure; and

respectively determining the first control current and the second control current according to the first output displacement and the second output displacement.

8. The control method according to claim 7, wherein determining the first required displacement of the first main pump and the second required displacement of the second main pump according to the pilot pressure comprises:

determining the first required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and

determining the second required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure.

9. The control method according to claim 8, wherein determining the first required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure comprises:

respectively determining a left traveling required displacement, a boom raising required displacement, a boom lowering required displacement, a bucket close required displacement, a bucket dump required displacement, an arm in required displacement and an arm out required displacement according to the left traveling pilot pressure, the boom raising pilot pressure, the boom lowering pilot pressure, the bucket close pilot pressure, the bucket dump pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and

using a maximum value among the left traveling required displacement, the boom raising required displacement, the boom lowering required displacement, the bucket close required displacement, the bucket dump required displacement, the arm in required displacement and the arm out required displacement as the first required displacement.

10. The control method according to claim 8, wherein determining the second required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure comprises:

respectively determining a right traveling required displacement, a swing required displacement, a boom raising required displacement, an arm in required displacement and an arm out required displacement according to the right traveling pilot pressure, the swing pilot pressure, the boom raising pilot pressure, the arm in pilot pressure and the arm out pilot pressure; and

using a maximum value among the right traveling required displacement, the swing required displacement, the boom raising required displacement, the arm in required displacement and the arm out required displacement as the second required displacement.

11. The control method according to claim 7, wherein determining the first set power of the first main pump and the second set power of the second main pump according to the first preset power proportion, the second preset power proportion, the first required displacement, the second required displacement, the gear position, the engine speed, the first pressure and the second pressure comprises:

determining a sum of maximum output power of the first main pump and the second main pump according to the gear position;

determining first preset power of the first main pump and second preset power of the second main pump according to the first preset power proportion, the second preset power proportion and the sum of maximum output power;

determining first required power of the first main pump and second required power of the second main pump according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure; and

determining the first set power and the second set power according to the first preset power, the second preset power, the first required power and the second required power.

12. The control method according to claim 11, wherein determining the first required power of the first main pump and the second required power of the second main pump according to the first required displacement, the second required displacement, the engine speed, the first pressure and the second pressure comprises:

determining the first required power according to a formula below:

wherein power_pilot1 is the first required power, q1 is the first required displacement, n is the engine speed, and p1_press is the first pressure; and

determining the second required power according to a formula below:

wherein power_pilot2 is the second required power, q2 is the second required displacement, n is the engine speed, and p2_press is the second pressure.

13. The control method according to claim 11, wherein determining the first set power and the second set power according to the first preset power, the second preset power, the first required power and the second required power comprises:

determining a maximum value in the first preset power and the first required power as the first set power; and

determining a maximum value in the second preset power and the second required power as the second set power.

14. The control method according to claim 7, wherein determining the first output displacement of the first main pump and the second output displacement of the second main pump according to the first set power, the second set power, the engine speed, the first pressure and the second pressure comprises:

determining the first output displacement according to a formula below:

wherein q1_set is the first output displacement, power _set1 is the first set power, n is the engine speed, and p1_press is the first pressure; and

determining the second output displacement according to a formula below:

wherein q2_set is the second output displacement, power_set2 is the second set power, n is the engine speed, and p2_press is the second pressure.

15. The control method according to claim 7, wherein respectively determining the first control current and the second control current according to the first output displacement and the second output displacement comprises:

determining the first control current according to a formula below:

wherein set _current1 is the first control current, q1_set is the first output displacement, q1 min is a non-zero lower limit value of a value range of an output displacement of the first main pump, q1_max is an upper limit value of the value range of the output displacement of the first main pump, c1_min is a non-zero lower limit value of a value range of a control current of the first main pump, and c1_max is an upper limit value of the value range of the control current of the first main pump; and

determining the second control current according to a formula below:

wherein set_current2 is the second control current, q2_set is the second output displacement, q2_min is a non-zero lower limit value of a value range of an output displacement of the second main pump, q2_max is an upper limit value of the value range of the output displacement of the second main pump, c2_min is a non-zero lower limit value of a value range of a control current of the second main pump, and c2_max is an upper limit value of the value range of the control current of the second main pump.

16. A controller, configured to execute the control method for the positive flow excavator according to any one of claims 1 to 15.

17. A control device for a positive flow excavator, the positive flow excavator comprising a control mechanism, an engine, a first main pump, a second main pump, a first main pump solenoid valve and a second main pump solenoid valve, and the control device comprising:

an arm in pilot pressure sensor, configured to detect an arm in pilot pressure;

an arm out pilot pressure sensor, configured to detect an arm out pilot pressure;

a swing pilot pressure sensor, configured to detect a swing pilot pressure;

a left traveling pilot pressure sensor, configured to detect a left traveling pilot pressure;

a right traveling pilot pressure sensor, configured to detect a right traveling pilot pressure;

a boom raising pilot pressure sensor, configured to detect a boom raising pilot pressure;

a boom lowering pilot pressure sensor, configured to detect a boom lowering pilot pressure;

a bucket close pilot pressure sensor, configured to detect a bucket close pilot pressure;

a bucket dump pilot pressure sensor, configured to detect a bucket dump pilot pressure;

a first main pump pressure sensor, configured to detect a first pressure of the first main pump;

a second main pump pressure sensor, configured to detect a second pressure of the second main pump;

an engine controller, configured to provide an engine speed;

a throttle knob, configured to provide a gear position of the engine; and

the controller according to claim 16.

18. A positive flow excavator, comprising:

a control mechanism;

an engine;

a first main pump;

a second main pump;

a first main pump solenoid valve;

a second main pump solenoid valve; and

the control device for the positive flow excavator according to claim 17.

Drawing