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(11) | EP 4 353 913 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | CONTROL AND COMMAND ASSEMBLY FOR A LIFTING ARM OF AN OPERATING MACHINE |
| (57) A control and command assembly for a lifting arm (13) of an operating machine (10)
comprising: - a hydraulic system (30) comprising: ▪ a valve distributor (31) comprising one or more sections (S1,...S4) connectable to respective utilities (131,132,133,134); ▪ an operating fluid supply apparatus (32) comprising a pump (320) adapted to supply the pressurized operating fluid to the valve distributor (31); ▪ an operating fluid discharge tank (T) connected to one or more discharge sections of the respective utilities (131,132,133,134); and ▪ an adjustable pressure limiting valve (35) configured to limit a maximum pressure of the operating fluid in the valve distributor (31); wherein the control and command assembly further comprises: - at least one sensor (411,412,413,414,415) configured to detect an operating parameter of the operating machine (10); and - an electronic control unit (45) operatively connected to the sensor (41,42,43,44); characterized in that the pressure limiting valve (35) is an electronically controlled valve that is operatively connected to the electronic control unit (45) and the electronic control unit (45) is configured to: detect a value of the operating parameter via the sensor (411,412,413,414,415); determine a maximum permissible pressure value in the valve distributor (31) as a function of the value of the detected operating parameter; and set the pressure limiting valve (35) at the determined maximum permissible pressure value. |
TECHNICAL FIELD
[0001] The present invention concerns a control and command assembly for a lifting arm of an operating machine, for example telescopic lifts or telehandlers, for example of an agricultural type.
[0002] More particularly, the invention concerns a control and command assembly of a hydraulic system intended for driving one or more hydraulic actuators, for example enslaved to a lifting arm of an operating machine (or operating vehicle).
PRIOR ART
[0003] As is well known, an operating machine is provided with a lifting arm, which is generally rotatable between a lowered and a raised position by means of a hydraulic actuator and is extendable, e.g. telescopically, between a contracted and an extended position by means of at least one further hydraulic actuator.
[0004] In addition, the operating machine may have additional auxiliary hydraulic actuators enslaved to the lifting arm and/or to the work tool, such as buckets, forks or other, which is connected to the free end of the lifting arm for the movement thereof.
[0005] These operating machines have a motor, generally endothermic, which drives a pump for the supply of pressurized oil sent to a hydraulic valve distributor, through which the various hydraulic actuators are operated individually and/or simultaneously.
[0006] Lately, the use of operating machines in which the motor is no longer exclusively endothermic, but for example is flanked (in hybrid operating machines) or replaced (in electric machines) by an electric motor has been developing.
[0007] The use of electric motors and/or the reduction in the power of endothermic motors, required by increasingly stringent environmental regulations, requires on the one hand that the operating machine maintains the performance (of speed in the displacements and of power at the lifting arm) of an operating machine equipped with the endothermic motor only, but at the same time requires greater attention to energy savings, in order to be able to increase the working autonomy of the operating machine.
[0008] An object of the present invention is to solve such needs of the prior art, as part of a simple, rational and cost-effective solution.
[0009] These objects are achieved by the features of the invention set forth in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.
DISCLOSURE OF THE INVENTION
[0010] The invention, in particular, makes available a control and command assembly for a lifting arm of an operating machine comprising:
- a hydraulic system comprising:
▪ a valve distributor comprising one or more sections connectable to respective utilities;
▪ an operating fluid supply apparatus comprising a supply pump adapted to supply the pressurized operating fluid to the valve distributor;
▪ an operating fluid discharge tank connected to one or more discharge sections of the respective utilities; and
▪ an adjustable pressure limiting valve configured to limit a maximum pressure of the operating fluid in the valve distributor;
- at least one sensor configured to detect an operating parameter of the operating machine, preferably of the lifting arm (and/or other utility associated with the operating machine); and
- an electronic control unit operatively connected to the sensor;
characterized in that the pressure limiting valve is an electronically controlled valve that is operatively connected to the electronic control unit and the electronic control unit is configured to:detect an operating parameter value via the sensor;
determine a maximum permissible pressure value in the valve distributor as a function of the value of the detected operating parameter; and set the pressure limiting valve at the determined maximum permissible pressure value.
[0012] In particular, some operating steps of an operating machine have been observed to have an increase in pressure in the hydraulic system, but not to produce actual work.
[0013] For example, these operating steps have been identified mainly in reaching the end strokes of each oleodynamic actuator enslaved to the operating machine (such as the actuator responsible for lifting the lifting arm, the actuator responsible for extending the lifting arm, the actuator for moving the work tool, etc.), since although the actuator has reached its mechanical end stroke end, for a few moments, the hydraulic system still sends pressurized operating fluid to the actuator.
[0014] Other operating steps of this kind have been observed in the use of work tools that do not require high pressures or in certain work steps, like for example in the initial steps of each movement of the lifting arm.
[0015] Well, thanks to this solution it is possible to impose a pressure limitation on the hydraulic system in such energy-consuming steps, thus allowing a saving of power and, hence, of energy (fuel and/or electric charge) in steps that are not purely operational of the operating machine.
[0016] Moreover, thanks to this solution, mechanical stresses on moving parts such as kinematics and/or actuators can be limited.
[0017] Again, thanks to this solution it is possible to undersize the endothermic motor of a hybrid operating machine while maintaining the same performances as an operating machine equipped with a more powerful endothermic motor.
[0018] According to one aspect of the invention, the pump can be a fixed displacement pump driven by a motor of the operating machine.
[0019] Again, the sensor may be selected from the group consisting of (or comprising):
- a first sensor configured to directly or indirectly detect an inclination or angular position of the lifting arm;
- a second sensor configured to directly or indirectly detect an extension of the lifting arm;
- a third sensor configured to directly or indirectly detect a load weighing on the lifting arm;
- a fourth sensor configured to directly or indirectly detect the inclination or angular position of a tool-carrying plate and/or a work tool associated with the lifting arm;
- an auxiliary sensor defined by a sensor configured to detect a stroke end of any actuator associated with the operating machine 10 valve distributor of the hydraulic system and/or an automatic work tool recognition sensor associated with the lifting arm and/or the tool-carrying plate; and
- combination of the same.
[0020] Advantageously, the pressure limiting valve can be integrated into the valve distributor. Alternatively, the pressure limiting valve may be located upstream of the valve distributor, interposed between the supply pump and the valve distributor.
[0021] Preferably, the electronic control unit may be configured to:
- determine at least one displacement stretch of a displacement stroke of the lifting arm as a function of the detected operating parameter, wherein the displacement stroke stretch is less than the entire displacement stroke permissible to the lifting arm;
- determine a first maximum permissible pressure value in the valve distributor and a second maximum permissible pressure value in the distributor, wherein the second maximum pressure value is less than the first maximum pressure value;
- set the pressure limiting valve at the determined second pressure value during the displacement of the lifting arm along the determined displacement stretch; and
- set the pressure limiting valve at the determined first pressure value during the displacement of the lifting arm along the displacement stroke outside said displacement stretch.
[0022] For example, the displacement stretch can be an end stretch (of end stroke) of the displacement stroke.
[0023] Advantageously, the pressure limiting valve may be adjustable so that the shutter thereof opens at any settable pressure value of the operating fluid (upstream of the pressure limiting valve) comprised between a minimum value and a maximum value (included). Again, the pressure limiting valve may be configured to discharge, for example into the tank, a flow rate of pressurized operating fluid (for instance from the supply channel or from the Load Sensing channel) so as to maintain/limit the pressure of the operating fluid in the valve distributor always at a pressure less than the determined maximum permissible pressure value, namely less than the above said set pressure value (comprised between the minimum value and the maximum value).
[0024] A further aspect of the invention makes available an operating machine provided with a lifting arm comprising a control and command assembly according to any one of the preceding claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Further features and advantages of the invention will be more apparent after reading the following description provided by way of a non-limiting example, with the aid of the accompanying drawings.
Figure 1 is a schematic view of an operating machine according to the invention.
Figure 2 is a system diagram of a hydraulic system, according to a first embodiment of the invention.
Figure 3 is a system diagram of a hydraulic system, according to a second embodiment of the invention.
Figure 4 is a system diagram of a hydraulic system, according to a third embodiment of the invention.
Figure 5 is a schematic view of an electronic control and command assembly of an operating machine according to the invention.
BEST MODE TO IMPLEMENT THE INVENTION
[0026] With particular reference to these figures, an operating machine (or operating vehicle) has been indicated globally with 10.
[0027] The operating machine 10 is provided with a load-bearing frame 11 movable on wheels 12 and supporting a lifting arm 13 (and a driver's cab) above.
[0029] In particular, the lifting arm 13 has a plurality of sections that can be driven between a contracted position and an extended position by means of a first oledynamic (double-acting) actuator 131.
[0030] The lifting arm 13 is hinged to the load-bearing frame 11 (by means of its proximal section) so as to be able to oscillate around a (single) axis of oscillation by means of a second oleodynamic (double-acting) actuator 132.
[0031] The lifting arm 13 has, at its distal end, a connection member, for example defined by a tool-carrying plate 130, which is adapted to connect to one or more work tools 14, like for example buckets, forks or other.
[0032] The tool-carrying plate 130, for example, is hinged (or articulated) to the distal end of the lifting arm 13 with the ability to oscillate about a further axis of rotation, for example parallel to the axis of oscillation of the lifting arm 13. The lifting arm 13 further comprises a third (double-acting) oleodynamic actuator 133, which is configured to move (for example, rotate around its axis of rotation and/or open and clamp the members of a bucket or other) the tool-carrying plate 130 (and therefore the work tool 14 and/or parts thereof associated therewith).
[0033] In addition, it may be envisaged that the lifting arm 13 may comprise one or more fourth auxiliary actuators 134, for example enslaved to the connection member or to further utilities of the lifting arm 13 and/or of the operating machine 10, or other.
[0034] Furthermore, it is not ruled out that the operating machine 10 also comprises a further rear hydraulic outlet (for example, when the operating machine is used/usable in the agricultural field).
[0035] The operating machine 10 further comprises a powertrain 20 for driving the drive wheels 12 and, indirectly, for moving the lifting arm 13.
[0037] For example, the powertrain comprises (or consists of) an endothermic motor 21. Alternatively, the powertrain comprises (or consists of) an electric motor 22.
[0038] Preferably, the powertrain 20 is of the hybrid type, i.e. it comprises an endothermic motor 21 and an electric motor 22.
[0039] Furthermore, the operating machine 10 comprises a control and command assembly for the movement of the lifting arm 13, i.e. configured to control and command the movement, for example individually and/or simultaneously, of one or more uses, each of which is defined by a respective actuator 131,132,133,134 of the lifting arm 13.
[0040] The control and command unit, in particular, comprises a hydraulic system 30 for controlling and commanding the movement of the lifting arm 13, i.e. configured to control and command the movement of one or more uses, each of which is defined by a respective actuator 131,132,133,134 of the lifting arm 13, for example individually and/or simultaneously.
[0041] The hydraulic system 30, preferably, comprises a valve distributor 31 comprising one or more sections S1, ..., S4 (in the example 4 in number), each of which can be connected to a respective use, or to a respective actuator 131,132,133,134.
[0042] Each section S1, ..., S4 comprises a respective slider 310 (or slide valve) configured to supply a flow rate of operating fluid (oil) necessary for driving the respective actuator. The hydraulic system 30 further comprises a supply apparatus 32, which is configured to supply a flow rate of operating fluid to the valve distributor 31.
[0043] The supply apparatus 32 comprises, in turn, a pump 320, which is connected to (and takes its motion from) the powertrain 20.
[0044] For example, the pump 320 is a fixed displacement pump (and rotates at the same revolutions as the motor 21, 22 of the powertrain 20).
[0045] However, it is not ruled out that the pump 320 could be a variable displacement pump or of other types depending on the construction requirements.
[0046] To the pump 320 a supply channel 321 is connected, through which the operating fluid is sent from the pump 320 to the valve distributor 31, i.e. it is supplied at high pressure P to the various sections S1, ..., S4 of the valve distributor 31, as will be better described below.
[0047] The supply system 32 further comprises a low pressure tank T to which the discharges of the uses (i.e. of each actuator 131,132,133,134) are connected, via one or more discharge channels 33.
[0048] The pump 320 is, for example, configured to draw operating fluid from said tank T or from other suitable tank.
[0049] In a second and third embodiment, shown in Figures 3 and 4, the hydraulic system 30 may be, respectively, of the Load Sensing or Adaptive Load Sensing type.
[0050] In particular, in the second embodiment a local compensator C1 ,...,C4 may be connected to or comprise each section S1, ... , S4 (or slider 310).
[0051] In addition, the hydraulic circuit 30 comprises a hydraulic adjustment device 34 (or compensating valve) associated with the valve distributor 31.
[0052] The hydraulic adjustment device 34 may be integrated with the valve distributor or separated therefrom.
[0053] In the hydraulic system 30 there is a Load Sensing LS signal channel coming from the sections S1, ... , S4 (i.e. from the sliders 310) of the valve distributor 31.
[0054] The Load Sensing LS signal channel is configured to receive from the sliders 310 of the valve distributor 31 a Load Sensing signal, to which a Load Sensing pressure corresponds.
[0055] In particular, the Load Sensing LS signal channel receives from the slider 310 of a respective section S1,..., S4 a signal characteristic of the corresponding use (i.e. of the respective actuator 131,132,133,134) representative of the pressure characteristic of the specific operating condition of the use.
[0056] The pressure difference between the delivery pressure P of the supply pump 32 and the Load Sensing pressure defines the so-called Standby pressure Pstb.
[0057] In the second embodiment shown in Figure 3, the hydraulic adjustment device 34 is configured so that the aforesaid Standby pressure Pstb is constant.
[0058] In the third embodiment shown in Figure 4, the hydraulic adjustment device 34 is configured so that the aforesaid Standby pressure Pstb is adjustable (electronically), for example by means of a Load Sensing pressure conditioned by an electronically managed valve (integrated into the hydraulic adjustment device 34).
[0059] The hydraulic system 30 further comprises an adjustable pressure limiting valve 35 configured to limit a maximum pressure of the operating fluid in the valve distributor 31.
[0060] In the first embodiment shown in Figure 2, the pressure limiting valve 35 is located upstream of the valve distributor 31 (i.e., of each section S1, ..., S4 thereof), i.e., made in a separate component.
[0061] It is not excluded, however, that in this embodiment the pressure limiting valve 35 can be integrated into the valve distributor 31 (upstream of each section S1, ..., S4 thereof). The pressure limiting valve 35, for example, is located on the supply channel 321 interposed between the pump 320 and the valve distributor 31.
[0062] In the second and third embodiment shown in Figures 3 and 4, the pressure limiting valve 35 is integrated within the valve distributor 31.
[0063] In this case, the pressure limiting valve 35 may be an accessory that can be combined to the valve distributor 31 (e.g., a commercial valve device).
[0064] For example, the pressure limiting valve 35 is interposed between the Load Sensing channel LS and the discharge (i.e., the tank T).
[0065] In this way, the pressure limiting valve 35 can be contained/undersized as it is crossed by lesser flow rates of fluid (compared to the case in which it were located between the supply channel 321 and the discharge).
[0066] It cannot be ruled out that in this second or third embodiment the pressure limiting valve 35 can be located externally with respect to the valve distributor 31 (for example upstream thereof), for example in any case interposed between the Load Sensing LS channel and the discharge (i.e. the tank T).
[0067] The pressure limiting valve 35, according to the present invention, is an electronically controlled/controllable valve, for adjusting the maximum pressure set by it in the valve distributor 31.
[0068] In particular, the (mechanical) mechanism for adjusting the maximum pressure of the pressure limiting valve 35 is actuated by a command actuator, for example a solenoid or with a stepper motor, electrically controlled.
[0069] In particular, the pressure limiting valve 35 is adjustable so that the shutter thereof opens at any settable pressure value of the operating fluid (upstream of the pressure limiting valve 35) ranging between a minimum value and a maximum value (included).
[0070] The pressure limiting valve 35 is configured to discharge, for example into the tank T, a flow rate of pressurized operating fluid (either from the supply channel 321 or from the Load Sensing LS channel) so as to maintain/limit the pressure of the operating fluid in the valve distributor 31 always at a pressure less than the set pressure value (ranging between the minimum value and the maximum value).
[0071] The hydraulic system 30 may further comprise at least one over-center valve (not illustrated), for example for one or more of the utilities.
[0072] The over-center valve is for example interposed between the slider 310 of the section S1, ..., S4 and the respective actuator 131,132,133,134 and is configured so as to maintain the load even in the event of breakage and malfunction (breakage of a pipe or other) of the hydraulic system 30.
[0073] In particular, the over-center valve is calibrated so as to allow the movement of the respective actuator 131,132,133,134 only if the pressure supplied to the system, used as internal piloting, exceeds a determined pressure proportional to the calibration of the valve itself and dependent on the piloting ratio.
[0074] The minimum value of the pressure limiting valve 35 is calibrated so as to be (slightly) higher (and not equal) to the piloting pressure of the over-center valve, so as to guarantee the actuation of the movement itself.
[0075] The hydraulic system 30 may further comprise one or more anti-impact/anti-cavitation valves on one or both channels (delivery and discharge) of one or more of the sections S1, ..., S4 to the utilities (i.e. to the actuators 131,132,133,134).
[0076] The control and command assembly also comprises an electronic control assembly 40, which is configured to control the operating machine 10 and, for example, the hydraulic system 30 thereof.
[0078] In particular, the sensor assembly comprises at least one sensor configured to detect an operating parameter of the operating machine 10, preferably (but not limited to) the lifting arm 13 (and/or of the work tool 14 associated therewith).
[0079] The sensor assembly, for example, comprises at least a first sensor 411 configured to (directly or indirectly) detect the inclination or angular (real-time) position of the lifting arm 13.
[0080] The first sensor 411 could comprise or consist of either one or more angle sensors (e.g. configured to detect an absolute or relative inclination with respect to a zero position, defined by a lower end stroke of the lifting arm 13) or one or more sensors associated with the second actuator 132, like for example a position sensor, wherein the sensor is configured to detect the stroke and/or the position (either absolute or relative with respect to a zero position, defined by an end stroke of the extent of the second actuator 132) of the second actuator 132.
[0081] The sensor assembly, for example, comprises at least one second sensor 412 configured to (directly or indirectly) detect the extension of the lifting arm 13, for example configured to detect the length or (real-time) extension of the lifting arm 13 (e.g., an absolute or relative length with respect to a defined end stroke position when the lifting arm 13 is in its contracted position).
[0082] The second sensor 412 may comprise or consist of one or more position sensors associated with the lifting arm 13 and/or with the first actuator 131. For example, configured to detect the stroke and/or the position (either absolute or relative with respect to a zero position, defined by an end stroke of the extent of the second actuator 132) of the second actuator 132.
[0083] The sensor assembly, for example, comprises at least a third sensor 413 enslaved to the lifting arm 13.
[0084] For example, the third sensor 413 comprises or consists of a load sensor, which is for example configured to detect a value of load acting on the lifting arm 13 (wherein for example the detected load value is an absolute or relative value with respect to a condition of zero load acting on the lifting arm 13).
[0085] The sensor assembly, for example, comprises at least a fourth sensor 414 configured to (directly or indirectly) detect the inclination or angular (real-time) position of the tool-carrying plate 130 and/or the work tool 14 (associated with the lifting arm 13).
[0086] The fourth sensor 414 could comprise or consist of one or more angle sensors (e.g., configured to detect an absolute or relative inclination with respect to a zero position, defined by a lower end stroke of the tool-carrying plate 130 and/or of the work tool 14) or one or more sensors associated with the third actuator 133, like for example a position sensor, wherein the sensor is configured to detect the stroke and/or the position (either absolute or relative with respect to a zero position, defined by an end stroke of the extent of the third actuator 132) of the third actuator 132.
[0087] The sensor assembly may comprise one or more auxiliary sensors 415 configured to detect other operating parameters of the operating machine 10 (and any hydraulic accessories commanded by the hydraulic system 30) and/or of the lifting arm 13 and/or of the work tools 14 connected thereto, like for example the movement (inclination/position) of the work tools 14, such as the bucket or other, the position of the connection member. For example, the auxiliary sensors 415 may comprise or consist of sensors adapted to detect an end stroke of a (any) (oleodynamic) actuator associated with the operating machine 10 and/or with the lifting arm 13 and/or with the work tool 14 (when connected to the lifting arm 13) and/or any hydraulic accessory hydraulically connected to the hydraulic system 30 of the operating machine.
[0088] An auxiliary sensor 415 could comprise or consist of an automatic (known) recognition sensor (or sensor system) of the work tool 14, for example associated with the lifting arm 13 and/or with the tool-carrying plate 130.
[0089] The electronic control module 40 further comprises an electronic control module 45, which is for example on board the operating machine 10.
[0090] The electronic control module 45 is generally configured to receive commands from the operator as input and provide command signals as output to be made available to the operating machine 10 (e.g., to the powertrain 20 and/or to the hydraulic system 30). The electronic control module 45, for example, may comprise one or more commands which can be operated by the operator (not illustrated, as known).
[0091] For example, the commands may be arranged within the driver's cab positioned next to the lifting arm 13.
[0092] The operator may use the commands to control and/or command the movement of the lifting arm 13 and other.
[0094] The electronic control unit 450 may be any device/processor capable of executing machine-readable instructions such as, for example, a controller, an integrated circuit, a microchip, or the like.
[0095] As used herein, the term "operatively connected" means that the components are capable of exchanging data signals with each other such as, for example, electrical signals via conductive medium, electromagnetic signals via air, optical signals via optical waveguides, and the like.
[0096] The electronic control unit 450 may be provided with or connected to one or more memory modules, which may be any device capable of storing data and/or instructions and/or software programs readable and implementable by the electronic control unit 450.
[0097] The electronic control unit 450 is operatively connected to the powertrain and/or the hydraulic system and/or the sensor assembly, as will be better described below. According to a preferred aspect of the invention, the electronic control unit 450 is configured to detect a value of the operating parameter by means of one (any or each) sensor of the sensor assembly.
[0098] In practice, the electronic control unit 450 is configured to receive as input (individually and/or simultaneously) the values indicative of the inclination of the lifting arm 13 detected by means of the first sensor 411, the values indicative of the extension of the lifting arm 13 detected by means of the second sensor 412 and, for example, the values indicative of the load weighing on the lifting arm 13 detected by means of the third sensor 413 and/or the values indicative of the inclination/position of the work tool 14/tool-carrying plate 130 detected by means of the fourth sensor 414.
[0099] The electronic control unit 450 is then configured to determine a maximum permissible pressure value in the valve distributor 31 as a function of the detected operating parameter value.
[0100] For example, as a function of the inclination value and/or the extension value and/or the detected load value, the electronic control unit 450 determines (e.g., calculates or defines) a maximum permissible pressure value in the valve distributor 31 (in those working circumstances of the lifting arm 13).
[0101] For example, the electronic control unit 450 may be configured to determine the maximum permissible pressure value, for example, as output of a map or function or table (prestored in the memory unit) that receives as input the inclination value and/or of the extension value and/or of the detected load value.
[0102] The maximum permissible pressure value determined by the electronic control unit 450 ranges between the minimum value and the maximum value.
[0103] At this point, the electronic control unit 450 is configured to set the pressure limiting valve 35 at the determined maximum permissible pressure value (i.e., to command the adjustment of the pressure limiting valve 35 so that the shutter thereof opens at the set maximum permissible pressure value, ranging between the minimum value and the maximum value).
[0104] In particular, the electronic control unit 450 is configured to determine a maximum permissible pressure value (variable/dynamic) for pre-determined inclination values and/or extension values and/or load values detected.
[0105] In other words, the electronic control unit 450 is configured to vary the maximum permissible pressure value based on the inclination value and/or on the extension value and/or on the detected load value.
[0106] In practice, the electronic control unit 450 is configured to set the pressure limiting valve 35 at (at least) a determined first maximum permissible pressure value at one or more of the inclination values and/or extension values and/or load values detected and to set the pressure limiting valve 35 at (at least) a determined second maximum permissible pressure value different from the first maximum permissible pressure value at another (and different) one or more inclination values and/or extension values and/or load values detected.
[0107] For example, operationally, the electronic control unit 450 may be configured to limit the maximum pressure in the valve distributor 31 (and therefore at the utilities) in determined operating steps of the lifting arm 13 (which would be extremely energy-consuming, though not useful in terms of work, in the event that the pressure of the operating fluid is not limited).
[0108] Preferably, the electronic control unit 450 can be configured to limit the maximum pressure in the valve distributor 31 as one or both of the mechanical end strokes of one or each of the utilities (i.e., of one or each of the actuators 131,132,133,134) are approached.
[0109] In order to do this, the electronic control unit 450 is configured to determine at least one displacement stretch of a displacement stroke of the lifting arm 13 (i.e. of any one of the actuators 131,132,133,134) as a function of the operating parameter detected by the sensors 411,412,413,414.
[0110] For example, the displacement stroke stretch is less than the entire displacement stroke allowed for the lifting arm 13.
[0111] Preferably, the displacement stroke stretch is an end stretch of the displacement stroke, i.e. a displacement stroke stretch having at one of its ends an end stroke of the respective actuator 131,132,133,134 and at the opposite end an intermediate point of the stroke proximal to said end stroke.
[0112] The length of the displacement stroke stretch can be defined as a function of the needs and, in any case, it is a limited stroke stretch which is preparatory as the end stroke is approached (for example equal to or less than 1% of the respective entire displacement stroke or equal to or less than a variable percentage of the respective entire displacement stroke between 1% and 10% depending on the movement speed of the respective actuator).
[0113] The electronic control unit 450 is then configured to determine a first maximum permissible pressure value (e.g., equal to the aforementioned maximum value) in the valve distributor 31 and a second maximum permissible pressure value (e.g., equal to the aforementioned minimum value) in the valve distributor 31, wherein the second maximum pressure value is less than the first maximum pressure value.
[0114] At this point, the electronic control unit 450 is configured to set the pressure limiting valve 35 at the determined second (limited) maximum permissible pressure value during the displacement of the lifting arm 13 along the (only) determined displacement stretch and to set the pressure limiting valve 35 at the determined first maximum permissible pressure value during the displacement of the lifting arm 13 along the displacement stroke outside said displacement stretch, i.e. in the remaining displacement stroke between a displacement stretch (preceding a first end stroke) and the other displacement stretch (preceding the second end stroke).
[0115] In other words, the electronic control unit 450 is configured to limit the maximum permissible pressure in the valve distributor 31 in a displacement stretch (with limited and predetermined length) as one (any) end stroke (in any direction) of the lifting arm 13 (i.e. of any one of the actuators 131,132,133,134 thereof) is approached.
[0116] Advantageously, the electronic control unit 450 can be (also) configured to limit the maximum pressure in the valve distributor 31 during predetermined specific and/or critical movements of the lifting arm 13, for example in order to avoid an overload of parts of the operating machine 10 and/or parts external thereto.
[0117] In this case, the electronic control unit 450 is configured to determine at least one specific/critical movement of the lifting arm 13 (i.e. of any one of the actuators 131,132,133,134) as a function of the operating parameter detected by the sensors 411,412,413,414.
[0118] For example, the electronic control unit 450 can be configured to determine the specific/critical movement of the lifting arm 13 as a function of the operating parameter detected by the auxiliary sensor 415 (defining an operating condition of the connection member, of the bucket, for example when of the grab type, or various special work tools 14 designed to be used with operating pressures lower than the aforesaid maximum value or with lower lifting forces) or by the third (load) sensor 413 or by other sensors that define operating conditions of auxiliary (rear) hydraulic outlets, for example supplied with the operating machine 10 when used for agricultural applications.
[0119] The electronic control unit 450 is then configured to determine a maximum permissible pressure value (lower than the maximum value, for example equal to the minimum value) in the valve distributor 31 as a function of the specific/critical movement of the determined lifting arm 13.
[0120] The maximum permissible pressure value determined by the electronic control unit ranges between the minimum value and the maximum value (excluded).
[0121] At this point, the electronic control unit 450 is configured to set the pressure limiting valve 35 at the determined maximum permissible pressure value (i.e., to command the adjustment of the pressure limiting valve 35 so that the shutter thereof opens at the set maximum permissible pressure value, ranging between the minimum value included and the maximum value excluded) during the execution of the specific/critical movement of the lifting arm 13.
[0122] For example, the electronic control unit 450 may be configured to limit the maximum pressure in the valve distributor 31 as a function of a type of work tool 14 (which is associated with the lifting arm 13, for example by means of the tool-carrying plate 130).
[0123] In particular, the electronic control unit 450 can be configured to detect (i.e. like operating parameter of the operating machine 10 and/or of the lifting arm 13 and/or of the work tool 14) a type of working tool 14 associated with the lifting arm 13, by means of the (auxiliary sensors 415 defined by the) aforesaid recognition sensor.
[0124] The electronic control unit 450 is then configured to determine a maximum permissible pressure value (lower than the maximum value, for example equal to the minimum value) in the valve distributor 31 as a function of the type of work tool 14 detected.
[0126] The maximum permissible pressure value determined by the electronic control unit ranges between the minimum value and the maximum value (excluded).
[0127] At this point, the electronic control unit 450 is configured to set the pressure limiting valve 35 at the determined maximum permissible pressure value (i.e., to command the adjustment of the pressure limiting valve 35 so that the shutter thereof opens at the set maximum permissible pressure value, ranging between the minimum value included and the maximum value excluded) as long as the work tool 14 of the detected type is connected to (the tool-carrying plate 130 of) the lifting arm 13.
[0128] Again, the electronic control unit 450 may be configured to limit the maximum pressure in the valve distributor 31 during predetermined initial steps of movements of the lifting arm 13, for example in those cases where an over-center valve is present in the hydraulic system 30.
[0129] In this case, the electronic control unit 450 is configured to determine at least one predetermined initial step of movements of the lifting arm 13 (i.e. of any one of the actuators 131,132,133,134) as a function of the operating parameter detected by the sensors 411,412,413,414,415.
[0130] For example, an initial step may be defined by a first settable (e.g., a second) time starting from the actuation of any part of the stationary lifting arm 13.
[0131] The electronic control unit 450 is then configured to determine a maximum permissible pressure value in the valve distributor 31 as a function of the determined initial step of movements of the lifting arm 13.
[0132] The maximum permissible pressure value determined by the electronic control unit ranges between the minimum value (included) and the maximum value (excluded), for example it is equal to the minimum value.
[0133] At this point, the electronic control unit 450 is configured to set the pressure limiting valve 35 at the determined maximum permissible pressure value (i.e., to command the adjustment of the pressure limiting valve 35 so that the shutter thereof opens at the set maximum permissible pressure value, ranging between the minimum value included and the maximum value excluded) during the determined initial step of movement of the lifting arm 13 (i.e., in the aforesaid first working time).
1. A control and command assembly for a lifting arm (13) of an operating machine (10)
comprising:
- a hydraulic system (30) comprising:
▪ a valve distributor (31) comprising one or more sections (S1,...S4) connectable to respective utilities (131,132,133,134);
▪ an operating fluid supply apparatus (32) comprising a pump (320) adapted to supply the pressurized operating fluid to the valve distributor (31);
▪ an operating fluid discharge tank (T) connected to one or more discharge sections of the respective utilities (131,132,133,134); and
▪ an adjustable pressure limiting valve (35) configured to limit a maximum pressure of the operating fluid in the valve distributor (31);
wherein the control and command assembly further comprises:- at least one sensor (411,412,413,414,415) configured to detect an operating parameter of the operating machine (10); and
- an electronic control unit (45) operatively connected to the sensor (411,412,413,414,415);
characterized in that the pressure limiting valve (35) is an electronically controlled valve that is operatively
connected to the electronic control unit (45) and the electronic control unit (45)
is configured to:
detect a value of the operating parameter via the sensor (411,412,413,414);
determine a maximum permissible pressure value in the valve distributor (31) as a function of the value of the detected operating parameter; and set the pressure limiting valve (35) at the determined maximum permissible pressure value.
2. The control and command assembly according to claim 1, wherein the pump (320) is a
fixed displacement pump driven by a powertrain (20) of the operating machine (10).
3. The control and command assembly according to claim 1, wherein the sensor is selected
from the group consisting of:
- first sensor (411) configured to directly or indirectly detect an inclination or angular position of the lifting arm (13);
- a second sensor (412) configured to directly or indirectly detect an extension of the lifting arm (13);
- a third sensor (413) configured to directly or indirectly detect a load weighing on the lifting arm (13);
- a fourth sensor (414) configured to directly or indirectly detect the inclination or angular position of a tool-carrying plate (130) and/or a work tool (14) that are associated with the lifting arm (13);
- an auxiliary sensor (415) defined by a sensor configured to detect a stroke end of any actuator associated with the operating machine 10 valve distributor (31) of the hydraulic system (30) and/or an automatic work tool recognition sensor (14) associated with the lifting arm (13) and/or the tool-carrying plate (130); and
- combination of the same.
4. The control and command assembly according to claim 1, wherein the pressure limiting
valve (35) is integrated into the valve distributor (31).
5. The control and command assembly according to claim 1, wherein the pressure limiting
valve (35) is located upstream of the valve distributor (31), interposed between the
pump (320) and the valve distributor (31).
6. The control and command assembly according to claim 1, wherein the electronic control
unit (450) is configured to:
- determine at least one displacement stretch of a displacement stroke of the lifting arm (13) as a function of the detected operating parameter, wherein the displacement stroke stretch is less than the entire displacement stroke permissible to the lifting arm (13);
- determine a first maximum permissible pressure value in the valve distributor (31) and a second maximum permissible pressure value in the valve distributor (31), wherein the second maximum pressure value is less than the first maximum pressure value;
- set the pressure limiting valve (35) at the determined second pressure value during the displacement of the lifting arm (13) along the determined displacement stretch; and
- set the pressure limiting valve (35) at the determined first pressure value during the displacement of the lifting arm (13) along the displacement stroke outside said displacement stretch.
7. The control and command assembly according to the preceding claim, wherein the displacement
stretch is an end stretch of the displacement stroke.
8. The control and command assembly according to claim 1, wherein the pressure limiting
valve (35) is adjustable so that the shutter thereof opens at any settable pressure
value of the operating fluid comprised between a minimum value and a maximum value
included.
9. The control and command assembly according to claim 1 or claim 8, wherein the pressure
limiting valve (35) is configured to discharge into the tank (T) a flow rate of pressurized
operating fluid, so as to maintain/limit the pressure of the operating fluid in the
valve distributor (31) always at a pressure less than the determined maximum permissible
pressure value.
10. An operating machine (10) provided with a lifting arm (13) comprising a control and
command assembly according to any one of the preceding claims.