IMPROVED SYSTEM AND METHOD FOR CONTROLLING THE SHAKING FUNCTION OF A BUCKET FOR A WORK VEHICLE

Abstract

 Work vehicle (2) comprising a bucket (3) carried by a boom (4), and a control system (1) for controlling a shaking movement of the bucket (3), the control system (1) comprising a valve arrangement (11), a bucket actuator (6), an electronic control unit (16) and a joystick (15), the electronic control unit (16) comprising elaboration means configured to retrieve data related to a joystick alternate movement, elaborate this latter and provide consequently an alternate control signal (Q', Q") towards the valve arrangement (11); the control system comprising sensor means (17) configured to detect a position (γ', γ") of the bucket (3) with respect to the boom (4), the electronic control unit (16) being electrically connected to the sensor means (17), the elaboration means being configured to retrieve data from sensor means (17) and vary the amplitude of the alternate control signal (Q', Q") as a function of the retrieved position (γ', γ").

Description

TECHNICAL FIELD

[0001] The present invention concerns a system and method for controlling an alternate movement of a bucket of machine work vehicle.

[0002] The present invention finds its preferred, although not exclusive, application in a system and a method for controlling an earth-moving machine such as a wheel loader.

BACKGROUND OF THE INVENTION

[0003] Earth-moving vehicles such as wheel loaders comprises a bucket carried by a boom for moving the earth. In particular, the boom and the bucket are carried by respective hydraulic actuators that moves the bucket and the boom with respect to their hinge points.

[0004] Such hydraulic actuators are controlled by a joystick that is hand operated by the user to move the boom and bucket thereby moving the earth.

[0005] As shown in EP3719221 A1, it is known that there are some operations that needs a shaking of the bucket with respect to the boom. Such shaking is obtained, according to the method shown in EP3719221 A1, by recognizing a peculiar frequency of movement of the joystick imparted by the user and providing by consequence an alternate control signal, i.e. a dumping and a rollback signal, to the valve means that controls the bucket actuator.

[0006] Thanks to the system proposed in EP3719221 A1, the comfort of the vehicle user is improved since the vehicle automatically recognizes the need of providing a shaking of the bucket.

[0007] However, the shaking movement of the bucket may be used for different purposes.

[0008] According to a first purpose, the shaking is a smooth shaking used for metering operations, i.e. for providing a material carried in the bucket to the ground with a sufficient precision while the vehicle is moving.

[0009] According to a second purpose, the shaking is a hard shaking that is used for cleaning operation, i.e. to allow the user to clean the bucket from the carried material; usually such operation is carried with standstill vehicle.

[0010] The system described in EP3719221 A1 provides an alternate signal whose amplitude is fixed. Therefore, once the shaking command is recognized by movement of the joystick the shaking is activated with the same amplitude for both the above described operational purposed.

[0011] Therefore, the need is felt to improve the comfort and the precision during bucket shaking operations.

[0012] An aim of the present invention is to satisfy the above mentioned needs in a cost effective and optimized way.

SUMMARY OF THE INVENTION

[0013] The aforementioned aim is reached by a system and related control method as claimed in the appended set of claims.

BRIEF DESCRIPTION OF DRAWINGS

[0014] For a better understanding of the present invention, a preferred embodiment is described in the following, by way of a non-limiting example, with reference to the attached drawings wherein:

• Figure 1 is a schematic representation of the control system according to the invention;
• Figures 2 and 3 are schematic representations of the operation of a boom and a bucket thanks to the control system of the invention; and
• Figure 4 is a graphical representation of actuation control signal amplitude provided by the control system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Figure 1 discloses a control system 1 of a work vehicle 2 (partially shown in figures 2 and 3) . The work vehicle 2 comprises a bucket 3 carried by a boom 4 and may advantageously be configured as a wheel loader.

[0016] The work vehicle 2 comprises a hydraulic circuit 5 configured to control the operation of a bucket actuator 6 and a boom actuator 7 by controlling the passage of fluid between a source 8 of fluid in pressure and a tank 9 of the work vehicle.

[0017] In particular, the hydraulic circuit 5 comprises a valve arrangement 11 that may be design as an open center distribution system provided with a pair of electric valves 12, 13 respectively voted to control the actuators 6, 7 in function of control signals acting on respective sides of the valves 12, 13 themselves. In particular, actuators 6, 7 are double effect hydraulic cylinders.

[0018] In particular, valves 12, 13 may be proportional six ways - three position valves wherein the six ways are fluidly connected, respectively (making reference to one of valves 12, 13) to 9, two of them to source 8, to two sides of the actuator 6, 7 and one to the other valve 12, 13. The valves 12, 13 may therefore assume at least the following limit positions: a first position wherein fluid may flow from source 8 to a first side of the actuator 6, 7 and the opposite one is fluidly connected to tank 9, a second position opposite with respect to the preceding and a third position wherein the source 8 is directly connected to tank 9(the one represented in figure 1) .

[0019] The control system 1 further comprises a joystick 15 configured to be handled to the user to impart a control signal for controlling bucket and boom actuators 6, 7 via valve arrangement 11.

[0020] The control system 1 further comprises an electronic control unit 16 that is electronically connected to joystick 15 and comprising elaboration means configured to retrieve data related to joystick position and to elaborate this latter to provide control signals to control valve arrangement 11, i.e. in the disclosed arrangement valves 12, 13.

[0021] Work vehicle 2 comprises sensor means 17 configured to detect the position of bucket 3. In particular, as depicted in figure 1, sensor means 17 may be position sensors carried by actuator means 6. However, it is clear that sensor means 17 may be of any typology, e.g. radar means or image acquisition means carried by the boom 4 and configured to detect position of bucket 3 or rotation position sensor carried in the hinge connection between the bucket 3 and boom 4.

[0022] In particular, the elaboration means are configured to detect the frequency of an alternate movement of the joystick 15 along a preset direction. In particular, the frequency may be elaborated by detecting the movement of the joystick 15 within a first position and a second position along a travel direction passing through a starting, rest, position.

[0023] If such frequency is higher with respect to a predefined preset threshold, then the control unit provides an alternate control signal, as shown in figure 4, to actuate the movement of valve 12 that control the bucket actuator 6 both in dumping and rollback direction.

[0024] The alternate control signal is preferably a square signal, that acts on opposite sides of valve 12 to move alternately the bucket 3 about its hinge axis. It is noticed that "alternate" means a signal that has the same amplitude both in dumping and in rollback direction, as shown in figure 4 graph.

[0025] The sensor means 17 are electrically connected to the electronic control unit 16 whose elaboration means are configured to elaborate the data retrieved to sensor means 17 and to vary accordingly the amplitude of the control signal defined by the elaboration of the joystick position, i.e. to vary the bucket shaking amplitude.

[0026] In particular, the frequency of the alternate control signal is fixed.

[0027] As said, the amplitude of the control signal is function of the data retrieved by sensor means 17. If sensor means 17 detects, in the time instant when the alternate control signal is commanded, that the bucket 3 is positioned with respect to boom 4 with an angle γ' lower than a predetermined angle γ, then the control signal will have an amplitude Q', while if it is detected a bucket position with respect to boom 4 with an angle γ" higher than the said angle γ, then the control signal will have an amplitude Q".

[0028] In particular, the first range of the bucket position angle γ '≤ γ is related to a metering operation of the vehicle 1 and therefore amplitude Q' is smaller than amplitude Q" that is related to the second range with a bucket position angle γ ">γ relating to a cleaning operation. The predetermined angle value γ is advantageously memorized in the elaboration means.

[0029] Accordingly, amplitude Q' makes rotate (see figure 2) the bucket 3 with an angular movement α over and under with respect to the bucket position angle γ', while amplitude Q" makes rotate (see figure 3) the bucket 3 with an angular movement β over and under with respect to the bucket position angle γ". According to the difference of amplitude of signals Q', Q" angular movement β is greater, in module, with respect to angular movement α.

[0030] The operation of the above described system is the following.

[0031] The operator will position the bucket 3 with respect to boom 4 according to the operative needs. Therefore, if a metering operation is needed, it will control the bucket 3 to be positioned with an angle γ '≤ γ, while if a cleaning operation is needed, the bucket will be controlled to be positioned with an angle γ "> γ. Then, when metering/shaking is needed, the driver will start an alternate movement of joystick that, over a predefined frequency, will be recognized by the electronic control unit 16. The electronic control unit 16 will receive data about the angle γ', γ ", will verify if γ '≤ γ or γ "> γ and associate a corresponding amplitude Q', Q" to the control signal for controlling valve 12.

[0032] In view of the above, the invention is furthermore related to a method for controlling an alternate movement of the bucket of the described work vehicle comprising the following steps:

i) Acquiring data related to the movement of the joystick 15;

ii)Elaborate the data retrieved in step i) to determine the frequency of an alternate movement of joystick 15 along a predetermined direction;

iii) If the frequency of the alternate movement is below a preset threshold, then return to step i), if the frequency of the alternate movement if over a preset threshold, then continue to step iv),

iv) Acquire data related to the position of the bucket 3 with respect to the boom 4 of the vehicle 2;

v) Associate an alternate control signal for controlling the actuator 6 of the bucket 3, such alternate control signal having an amplitude that is function of the position data acquired in step iv)

[0033] The control signal, the preset memorized values of the aforementioned steps are memorized in the elaboration means of control unit. Such elaboration means are furthermore configured to automatically execute the steps i) to v) during the entire operation of the vehicle.

[0034] In particular, step ii) may be executed continually in time or with a frequency of a preset time.

[0035] In view of the foregoing, the advantages of the control system and method according to the invention are apparent.

[0036] In particular, the efficiency of the operation is increased both in metering operation and in cleaning operation. Moreover, the comfort of the user is increased since the same command may be used for controlling the two different operations.

[0037] Furthermore, the optimization of the signal according to the detected position of the bucket best manages the valve arrangement 11 thereby reducing the oil consumption and, then, vehicle fuel consumption.

[0038] Furthermore, the proposed system is substantially compact and may be integrated or provided into already existing systems.

[0039] It is clear that modifications can be made to the described control system and method which do not extend beyond the scope of protection defined by the claims.

[0040] For example, the control signal may be a different signal, such as a sinusoidal signal.

[0041] Moreover, the provided valve arrangement may vary. Similarly, the provided control signals could be in greater number, with related different amplitudes, with respect to the described two positions.

Claims

1. Work vehicle (2) comprising a bucket (3) carried by a boom (4),said work vehicle (2) comprising a control system (1) for controlling a shaking movement of said bucket (3), said control system (1) comprising:

a valve arrangement (11) and a bucket actuator (6), said valve arrangement (11) being configured for providing fluid from a source (8) of fluid in pressure towards said bucket actuator (6);
an electronic control unit (16) and a joystick (15), said electronic control unit (16) being electrically connected to said joystick (15) and to said valve arrangement (11),

said electronic control unit (16) comprising elaboration means configured to retrieve data related to a joystick alternate movement, elaborate this latter and provide consequently an alternate control signal (Q', Q") towards said valve arrangement (11);
sensor means (17) configured to detect a position (γ', γ" ) of the bucket (3) with respect to said boom (4), said electronic control unit (16) being electrically connected to said sensor means (17),

said elaboration means being configured to retrieve data from said sensor means (17) and vary the amplitude of said alternate control signal (Q', Q") in function of said position (y', y").

2. Work vehicle according to claim 1, wherein said sensor means (17) are position sensors, said position sensors detecting a position of said bucket actuator (6).

3. Work vehicle according to claim 1 or 2, wherein said valve arrangement (11) is an open center valve arrangement.

4. Work vehicle according to any of claims 1 to 3, wherein said alternate control signal (Q',Q") is an alternate square signal.

5. Work vehicle according to any of the preceding claims, wherein said elaboration means are configured to memorize a preset bucket position angle (γ ), said elaboration means associating a first alternate control signal (Q') if the bucket position angle (γ') is equal or lower than said preset bucket position angle (γ) and a second alternate control signal (Q") if the bucket position angle (γ") is higher than said preset bucket position angle (γ), wherein the amplitude of said first alternate control signal (Q') is lower with respect to the amplitude of said second alternate control signal (Q").

6. Work vehicle according to any of the preceding claims, wherein the frequency of said alternate control signal (Q', Q") is constant with respect to said detected position ( γ', γ").

7. Method for controlling an alternate movement of the bucket (3) of a work vehicle (2) according to any of the preceding claims and comprising the following steps:

i) Acquiring data related to the movement of said joystick (15) ;

ii)Elaborate the data retrieved in step i) to determine the frequency of an alternate movement of said joystick (15) along a predetermined direction;

iii) If the frequency of the alternate movement is below a preset threshold, then return to step i), if the frequency of the alternate movement if over a preset thresholds, then continue to step iv),

iv) Acquire data related to the position of said bucket (3) with respect to the boom (4) of the vehicle (2);

v) Associate an alternate control signal for controlling said actuator (6) of said bucket (3), such alternate control signal having an amplitude that is function of the position data acquired in step iv).

Drawing