Variable speed-variable displacement differential pressure controllable valve front compensation load sensitive system and control method

Abstract

The invention provides a variable rotating speed-variable displacement differential pressure controllable valve front compensation load sensitive system. The variable rotating speed-variable displacement differential pressure controllable valve front compensation load sensitive system comprises a control unit, a driving motor assembly, a variable differential pressure load sensitive pump assembly, a variable differential pressure load sensitive valve assembly, a pilot hydraulic control unit, a pilot handle assembly, an actuator assembly, a sensor assembly and a motor rotating speed control module. The driving motor assembly drives the variable pressure difference load sensitive pump assembly to supply oil to the variable pressure difference load sensitive valve assembly, and then the actuator assembly is driven to operate. The pilot hydraulic control unit provides set pressure; the pilot handle assembly outputs a signal to the variable pressure difference load sensitive valve assembly; the sensor assembly detects the maximum load pressure of the system and the outlet pressure of the variable pressure difference load sensitive pump assembly; the control unit controls the target rotating speed of the driving motor assembly and the control pressure of the pilot hydraulic control unit. Compared with an existing upstream compensation load sensitive system, the problem of speed imbalance of an actuator under the flow saturation working condition is effectively avoided, and the control performance is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction machinery, and in particular, to a variable-speed - variable-displacement pressure-difference controllable valve-front compensated load-sensing system and a control method therefor. Background Art

[0002] Load-sensing systems achieve good multi-actuator control performance through pressure compensation and are widely used in construction machinery such as excavators and cranes. With the development of the electrification of construction machinery, problems such as large battery capacity, high cost, and limited endurance have imposed more stringent requirements on the energy-saving performance of load-sensing systems. Moreover, the development of intelligence has also put forward higher requirements for the control performance of load-sensing systems to cope with the complex operating conditions of construction machinery.

[0003] The valve-front compensated load-sensing system is more energy-saving in the spool structure of the multi-way valve compared to the valve-rear compensated load-sensing system and is more suitable for electric construction machinery. However, there is a problem of imbalance in the flow distribution ratio of actuators when the flow is saturated. In addition, the valve port pressure difference of traditional load-sensing systems is set conservatively and is set by a pressure-regulating spring, which cannot be dynamically adjusted during operation, resulting in large pressure difference losses at each throttle orifice, especially in the multi-actuator combined action conditions with high flow requirements. Moreover, the fixed setting of the pressure difference is difficult to balance the complex and variable operating condition requirements such as fine operation and fast combined action of construction machinery.

[0004] In view of this, the applicant has specifically proposed this application after studying the existing technologies. Summary of the Invention

[0005] The present invention provides a variable-speed - variable-displacement pressure-difference controllable valve-front compensated load-sensing system and a control method therefor, aiming to improve at least one of the above technical problems.

[0006] To solve the above technical problems, the present invention provides a variable-speed - variable-displacement pressure-difference controllable valve-front compensated load-sensing system, including a control unit, a drive motor assembly, a variable-pressure-difference load-sensing pump assembly, a variable-pressure-difference load-sensing valve assembly, a pilot hydraulic control unit, a pilot handle assembly, an actuator assembly, a sensor assembly, and a motor speed control module, wherein: The drive motor assembly is used to drive the variable-pressure-difference load-sensing pump assembly to operate, so that the variable-pressure-difference load-sensing pump assembly outputs high-pressure hydraulic oil to the variable-pressure-difference load-sensing valve assembly; the variable-pressure-difference load-sensing valve assembly is configured to regulate the flow rate entering the actuator assembly to drive the actuator assembly to operate; The pilot hydraulic control unit is connected to the input end of the pilot handle assembly, the variable differential pressure load sensing pump assembly, and the variable differential pressure load sensing valve assembly to provide set pressures for the pilot handle assembly, the variable differential pressure load sensing pump assembly, and the variable differential pressure load sensing valve assembly, respectively. The output end of the pilot handle assembly is connected to the variable differential pressure load sensing valve assembly, and is used to output a signal to the variable differential pressure load sensing valve assembly, so that the variable differential pressure load sensing valve assembly controls the target operating speed of the actuator assembly. The sensor assembly is used to detect the maximum load pressure of the system and the outlet pressure of the variable differential pressure load sensing pump assembly. The control unit is electrically connected to the sensor assembly, the motor speed control module, the drive motor assembly, and the pilot hydraulic control unit to collect and process the signals of the sensor assembly and the motor speed control module, and then control the target speed of the drive motor assembly and the control pressure of the pilot hydraulic control unit.

[0007] As a further optimization, the drive motor assembly includes a power supply, a motor driver, and a drive motor, the power supply is electrically connected to the input end of the motor driver, the output end of the motor driver is electrically connected to the drive motor, and the motor driver is configured to receive the target speed signal sent by the control unit and control the drive motor to operate at a speed corresponding to the target speed signal. The output end of the drive motor is mechanically connected to the variable differential pressure load sensing pump assembly coaxially, so as to drive the variable differential pressure load sensing pump assembly to operate.

[0008] As a further optimization, the variable differential pressure load sensing pump assembly includes a first-stage control valve, a second-stage control valve, a pump displacement regulating valve, and a variable pump. The output end of the first-stage control valve is connected to the input end of the second-stage control valve, the output end of the second-stage control valve is connected to the input end of the pump displacement regulating valve, and the output end of the pump displacement regulating valve is connected to the variable pump. The first-stage control valve is configured to output the actual load sensing differential pressure of the system, and the second-stage control valve is configured to output flow to the pump displacement regulating valve by comparing the actual load sensing differential pressure of the system with the pump target differential pressure, and then adjust the displacement of the variable pump.

[0009] As a further optimization, the pilot hydraulic control unit includes a pilot pump, a pilot relief valve, a first proportional relief valve, and a second proportional relief valve. The pilot overflow valve is arranged at the outlet of the pilot pump and is used to set the primary pilot pressure. The primary pilot pressure is respectively supplied to the input ends of the pilot handle assembly and the first-stage control valve, and is also supplied to the input ends of the first proportional pressure reducing valve and the second proportional pressure reducing valve; The output end of the first proportional pressure reducing valve is connected to the variable differential pressure load sensing pump assembly to provide the set pressure for the pump target differential pressure for the variable differential pressure load sensing pump assembly. The input end of the second proportional pressure reducing valve is connected to the variable differential pressure load sensing valve assembly to provide the set pressure for the valve target differential pressure for the variable differential pressure load sensing valve assembly.

[0010] As a further optimization, the variable differential pressure load sensing valve assembly includes a fixed differential overflow valve, a first pressure compensating valve, a first throttle orifice, a second pressure compensating valve, a second throttle orifice, and a shuttle valve, where: The fixed differential overflow valve is configured at the oil inlet of the variable differential pressure load sensing valve assembly. The first pressure compensating valve is communicated with the oil inlet of the first throttle orifice. The second pressure compensating valve is communicated with the oil inlet of the second throttle orifice. The shuttle valve is communicated with the oil outlets of the first throttle orifice and the second throttle orifice. The input ends of the first throttle orifice and the second throttle orifice are connected to the output end of the pilot handle assembly; One end of the spools of the first pressure compensating valve and the second pressure compensating valve respectively acts on the front-end pressure of the first throttle orifice and the second throttle orifice, and the other ends respectively act on the load pressure and the target control pressure at the rear ends of the first throttle orifice and the second throttle orifice. The target control pressure oil circuits of the first pressure compensating valve and the second pressure compensating valve are in parallel and are connected to the valve target differential pressure output by the pilot hydraulic control unit; The first pressure compensating valve and the second pressure compensating valve are configured to respectively maintain the pressure differences between the front and rear ends of the first throttle orifice and the pressure differences between the front and rear ends of the second throttle orifice at the valve target differential pressure of the variable differential pressure load sensing valve regulated by the second proportional pressure reducing valve in the pilot hydraulic control unit; The first throttle orifice and the second throttle orifice are configured to control the operating speed of the actuator assembly by adjusting the flow area; The fixed differential overflow valve is used to prevent system overpressure; The shuttle valve is used to obtain the maximum load pressure of the actuator drive chambers of each branch;

[0011] As a further optimization, one end of the spool of the first-stage control valve acts on the maximum load pressure obtained by the shuttle valve and the actual load sensing differential pressure of the system output by the first-stage control valve, and the other end of its spool acts on the outlet pressure of the variable pump. The input end of the first-stage control valve is connected to the primary pilot pressure port of the pilot hydraulic control unit, so as to realize that the output of the first-stage control valve is the actual load sensing differential pressure of the system; For the second - stage control valve, one end of its spool acts on the actual load - sensitive pressure difference of the system output by the first - stage control valve, and the other end of its spool acts on the pump target pressure difference output by the first proportional pressure reducing valve in the pilot hydraulic control unit. By comparing the pressure differences at both ends of the spool, the displacement of the variable - pressure - difference load - sensitive pump is adjusted accordingly. The displacement of the variable - pressure - difference load - sensitive pump assembly is configured to be controlled by the pump target pressure difference of the pilot hydraulic control unit. When the actual load - sensitive pressure difference of the system is greater than the pump target pressure difference, the pump displacement decreases; when the actual load - sensitive pressure difference of the system is less than the pump target pressure difference, the pump displacement increases.

[0012] As a further optimization, the actuator assembly includes a first actuator and a second actuator. The first actuator is connected to the output port of the first throttle port, and the second actuator is connected to the output port of the second throttle port.

[0013] As a further optimization, the sensor assembly includes a first pressure sensor and a second pressure sensor. The first pressure sensor is configured on the variable - pressure - difference load - sensitive valve assembly and is used to detect the maximum load pressure of the system. The second pressure sensor is configured on the connecting pipeline between the variable - pressure - difference load - sensitive pump assembly and the variable - pressure - difference load - sensitive valve assembly, and the second pressure sensor is used to detect the outlet pressure of the variable - pressure - difference load - sensitive pump assembly.

[0014] As a further optimization, the pilot handle assembly includes a first pilot handle and a second pilot handle. The input ends of the first pilot handle and the second pilot handle are connected to the pilot hydraulic control unit. The output ends of the first pilot handle and the second pilot handle are respectively connected to the opening control ends of the first throttle port and the second throttle port. The variable - pressure - difference load - sensitive valve assembly is configured to control the target operating speed of the actuator assembly according to the output signals of the first pilot handle and the second pilot handle respectively.

[0015] This application further provides a method for controlling a variable - speed - variable - displacement pressure - difference - controllable valve - front compensated load - sensitive system as described in any one of the above, including the following steps: S1: Obtain a target speed signal through the motor speed control module and send the signal to the control unit, and set the system target pressure difference to be proportional to the target speed signal. S2: Send a CAN signal to the drive motor assembly through the control unit to make the motor operate at the target speed value. S3: Set the pump target pressure difference to be equal to the system target pressure difference value. Send a PWM signal to the pilot hydraulic control unit through the control unit, and control the pump displacement of the variable - pressure - difference load - sensitive pump assembly through the pilot hydraulic control unit. S4: The control unit obtains the sensor information of the sensor assembly and calculates the actual pressure difference of the system, sets the valve target pressure difference to the actual pressure difference of the system, sends a PWM signal to the pilot hydraulic control unit through the control unit, and controls the pressure difference of the variable pressure differential load-sensitive valve assembly through the pilot hydraulic control unit.

[0016] By adopting the above technical solution, the present invention can achieve the following technical effects: The present application discloses a variable speed-variable displacement pressure difference controllable valve pre-compensation load-sensitive system. When the system is running, the pump displacement changes in real time to maintain the actual pressure difference of the system at the system target pressure difference. The system achieves good anti-flow saturation function by actively regulating the valve target pressure difference. Compared with the existing valve pre-compensation load-sensitive system, it effectively avoids the actuator speed imbalance problem under flow saturation conditions, and the control performance is significantly improved.

[0017] Furthermore, the system dynamically adjusts the target pressure differential through a speed-sensitive variable pressure differential control strategy. Under low-speed operating conditions, the target pressure differential is lowered to expand the effective control range and enable fine-tuning. Under high-speed operating conditions, the target pressure differential is increased to maximize flow gain and meet rapid response requirements. This feature addresses the limited control range caused by the fixed pressure margin of traditional load-sensitive systems and adapts to diverse flow requirements under complex operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic structural diagram of a variable speed-variable displacement pressure differential controllable valve pre-compensation load-sensing system provided by an embodiment of the present invention; Figure 2 The present invention provides a flow chart of a method for controlling a variable speed-variable displacement pressure difference controllable valve front compensation load-sensing system. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] Embodiment Please refer to Figure 1 , a variable speed - variable displacement pressure - difference controllable valve - front compensated load - sensing system of the present invention includes a control unit 1, a drive motor assembly 2, a variable pressure - difference load - sensing pump assembly 3, a variable pressure - difference load - sensing valve assembly 6, a pilot hydraulic control unit 4, a pilot handle assembly 5, an actuator assembly 7, a sensor assembly 8, and a motor speed control module 9; where: The drive motor assembly 2 is used to drive the variable pressure - difference load - sensing pump assembly 3 to operate, so that the variable pressure - difference load - sensing pump assembly 3 outputs high - pressure hydraulic oil to the variable pressure - difference load - sensing valve assembly 6, and the variable pressure - difference load - sensing valve assembly 6 is configured to regulate the flow rate entering the actuator assembly 7 to drive the actuator assembly 7 to operate; The pilot hydraulic control unit 4 is connected to the input end of the pilot handle assembly 5, the variable pressure - difference load - sensing pump assembly 3, and the variable pressure - difference load - sensing valve assembly 6 to provide set pressures for the pilot handle assembly 5, the variable pressure - difference load - sensing pump assembly 3, and the variable pressure - difference load - sensing valve assembly 6 respectively; The output end of the pilot handle assembly 5 is connected to the variable pressure - difference load - sensing valve assembly 6, and it is used to output a signal to the variable pressure - difference load - sensing valve assembly 6 to enable the variable pressure - difference load - sensing valve assembly 6 to control the target operating speed of the actuator assembly 7; The sensor assembly 8 is used to detect the maximum load pressure of the system and the outlet pressure of the variable pressure - difference load - sensing pump assembly; The control unit 1 is electrically connected to the sensor assembly 8, the motor speed control module 9, the drive motor assembly 2, and the pilot hydraulic control unit 4 to collect and process the signals of the sensor assembly 8 and the motor speed control module 9, and then control the target speed of the drive motor assembly 2 and the control pressure of the pilot hydraulic control unit 4.

[0022] Among them, the motor speed control module 9 is used to provide a target speed signal, which can be given by the driver through the speed knob and the working mode button, or can be automatically controlled by intelligently identifying the real-time operating conditions of the construction machinery.

[0023] In this embodiment, when the system is running normally, the pump displacement changes in real time to maintain the actual system pressure difference at the target system pressure difference. When the system enters the flow saturation state, the pump displacement reaches the maximum, and the actual system pressure difference will decrease, causing the valve target pressure difference to decrease synchronously, resulting in a decrease in the flow demand at the current flow area of each throttle orifice. When the total flow demand drops to be equal to the pump output flow, the actual system pressure difference and the valve target pressure difference stop decreasing and remain constant, reaching a new equilibrium state. During this process, the pump target pressure difference is the target system pressure difference, which is always greater than the actual system pressure difference, so the pump displacement always remains at the maximum. Further, when the flow area of each main spool valve of the system decreases, the actual system pressure difference will increase, causing the valve target pressure difference to increase synchronously. When the actual system pressure difference rises to be equal to the target system pressure difference, the pump displacement will show a downward trend to maintain the actual system pressure difference at the target system pressure difference. At this time, the system exits the flow saturation state. Therefore, the system realizes a good anti-flow saturation function through the active regulation of the valve target pressure difference. Compared with the existing valve front compensation load sensing system, it effectively avoids the actuator speed imbalance problem under the flow saturation condition, and significantly improves the control performance.

[0024] In addition, the system dynamically adjusts the target system pressure difference through a speed-sensitive variable pressure difference control strategy. It reduces the target system pressure difference under low-speed conditions to broaden the effective control stroke and achieve fine adjustment, and increases the target system pressure difference under high-speed conditions to increase the flow gain to meet the fast response requirements. This characteristic solves the problem of limited control stroke caused by the fixed pressure margin of the traditional load sensing system and adapts to the diverse flow demands under complex working conditions.

[0025] Specifically, the drive motor assembly 2 includes a power supply 21, a motor driver 22, and a drive motor 23. The power supply 21 is electrically connected to the input end of the motor driver 22, the output end of the motor driver 22 is electrically connected to the drive motor 23, and the output end of the drive motor 23 is mechanically connected coaxially to the variable pressure difference load sensing pump assembly 3; Among them, the motor driver 22 is configured to receive the target speed signal sent by the control unit 1 and control the drive motor 23 to operate at the speed corresponding to the target speed signal.

[0026] Specifically, the variable differential pressure load-sensitive pump assembly 3 includes a first-stage control valve 33, a second-stage control valve 31, a pump displacement regulating valve 32, and a variable pump 34. The output end of the first-stage control valve 33 is connected to the input end of the second-stage control valve 31. The output end of the second-stage control valve 31 is connected to the input end of the pump displacement regulating valve 32. The output end of the pump displacement regulating valve 32 is connected to the variable pump 34; Among them, the first-stage control valve 33 is configured to output the actual load-sensitive differential pressure of the system. The second-stage control valve 31 is configured to output flow to the pump displacement regulating valve 32 by comparing the actual load-sensitive differential pressure of the system with the pump target differential pressure, and then adjust the pump displacement.

[0027] Further, the pilot hydraulic control unit 4 includes a pilot pump 41, a pilot relief valve 42, a first proportional pressure reducing valve 43, and a second proportional pressure reducing valve 44. The pilot relief valve 42 is arranged at the outlet of the pilot pump 41 for setting the primary pilot pressure. The primary pilot pressure is respectively supplied to the input end of the pilot handle assembly 5 and the first-stage control valve 33 of the variable differential pressure load-sensitive pump assembly 3, and is also supplied to the input ends of the first proportional pressure reducing valve 43 and the second proportional pressure reducing valve 44; Among them, the output end of the first proportional pressure reducing valve 43 is connected to the variable differential pressure load-sensitive pump assembly 3 to provide the set pressure of the pump target differential pressure for the variable differential pressure load-sensitive pump assembly 3. The input end of the second proportional pressure reducing valve 44 is connected to the variable differential pressure load-sensitive valve assembly 6 to provide the set pressure of the valve target differential pressure for the variable differential pressure load-sensitive valve assembly 6.

[0028] Further, the variable differential pressure load-sensitive valve assembly 6 includes a fixed-differential relief valve 61, a first pressure compensating valve 62, a first throttle port 64, a second pressure compensating valve 63, a second throttle port 65, and a shuttle valve 66. The fixed-differential relief valve 61 is configured at the oil inlet of the variable differential pressure load-sensitive valve assembly 6. The first pressure compensating valve 62 is configured at the oil inlet of the first throttle port 64. The second pressure compensating valve 63 is configured at the oil inlet of the second throttle port 65. The shuttle valve 66 is configured at the oil outlets of the first throttle port 64 and the second throttle port 65. The input ends of the first throttle port 64 and the second throttle port 65 are connected to the output end of the pilot handle assembly 5; One end of the spools of the first pressure compensating valve 62 and the second pressure compensating valve 63 respectively acts on the front-end pressure of the first throttle port 64 and the second throttle port 65, and the other ends respectively act on the load pressure and the target control pressure at the rear ends of the first throttle port 64 and the second throttle port 65. The target control pressure oil circuits of the first pressure compensating valve 62 and the second pressure compensating valve 63 are in parallel and are connected to the valve target differential pressure output by the pilot hydraulic control unit 4; The first pressure compensation valve 62 and the second pressure compensation valve 63 are configured to maintain the pressure difference across the first throttle port 64 and the pressure difference across the second throttle port 65 at the valve target pressure difference of the variable pressure difference load sensing valve regulated by the second proportional pressure reducing valve 44 in the pilot hydraulic control unit 4 respectively; The first throttle port 64 and the second throttle port 65 are configured to control the operating speed of the actuator assembly 7 by adjusting the flow area of the hydraulic fluid; The fixed differential overflow valve 61 is used to prevent the system from overpressure; The shuttle valve 66 is used to obtain the maximum load pressure of the actuator drive chambers of each branch.

[0029] Further, one end of the spool of the first-stage control valve 33 acts on the maximum load pressure obtained by the shuttle valve 66 and the actual load sensing pressure difference of the system output by the first-stage control valve 33, and the other end of the spool acts on the outlet pressure of the variable pump 34. The input end of the first-stage control valve 33 is connected to the primary pilot pressure port of the pilot hydraulic control unit 4, so as to make the output of the first-stage control valve 33 be the actual load sensing pressure difference of the system; One end of the spool of the second-stage control valve 31 acts on the actual load sensing pressure difference of the system output by the first-stage control valve 33, and the other end of the spool acts on the pump target pressure difference output by the first proportional pressure reducing valve 43 in the pilot hydraulic control unit 4. By comparing the pressure differences at both ends of the spool, the displacement of the variable pressure difference load sensing pump is adjusted; The displacement of the variable pressure difference load sensing pump assembly 3 is configured to be controlled by the pump target pressure difference of the pilot hydraulic control unit 4. When the actual load sensing pressure difference of the system is greater than the pump target pressure difference, the pump displacement decreases; when the actual load sensing pressure difference of the system is less than the pump target pressure difference, the pump displacement increases.

[0030] Preferably, the actuator assembly 7 includes a first actuator 71 and a second actuator 72. The first actuator 71 is connected to the output port of the first throttle port 64, and the second actuator 72 is connected to the output port of the second throttle port 65. Wherein, the first actuator 71 and the second actuator 72 are hydraulic cylinders or hydraulic motors.

[0031] Preferably, the sensor assembly 8 includes a first pressure sensor 81 and a second pressure sensor 82. The first pressure sensor 81 is arranged on the variable pressure difference load sensing valve assembly 6. The first pressure sensor 81 is used to detect the maximum load pressure of the system. The second pressure sensor 82 is arranged on the connecting pipeline between the variable pressure difference load sensing pump assembly 3 and the variable pressure difference load sensing valve assembly 6. The second pressure sensor 82 is used to detect the outlet pressure of the variable pressure difference load sensing pump assembly 3.

[0032] Preferably, the pilot handle assembly 5 includes a first pilot handle 51 and a second pilot handle 52. The input ends of the first pilot handle 51 and the second pilot handle 52 are connected to the pilot hydraulic control unit 4. The output ends of the first pilot handle 51 and the second pilot handle 52 are connected to the opening control ends of the throttle ports in the variable differential pressure load sensing valve assembly 6. The variable differential pressure load sensing valve assembly 6 is configured to control the target operating speeds of the first actuator 71 and the second actuator 72 respectively according to the output signals of the first pilot handle 51 and the second pilot handle 52.

[0033] Reference Figure 2 As shown, a control method for a variable-speed - variable-displacement differential-pressure controllable valve front-compensation load sensing system of the present application is as follows: S1: Obtain the target speed signal through the motor speed control module 9 and send the signal to the control unit 1, and set the system target differential pressure to be proportional to the target speed signal; S2: Send a CAN signal from the control unit 1 to the drive motor assembly 2 to make the motor operate at the target speed value; S3: Set the pump target differential pressure to be equal to the system target differential pressure value. Send a PWM signal from the control unit 1 to the first proportional pressure reducing valve 43 in the pilot hydraulic control unit 4. The first proportional pressure reducing valve 43 outputs a control pressure to the second-stage control valve 31 in the variable differential pressure load sensing pump assembly 3, thereby controlling the pump displacement; S4: The control unit 1 obtains the information of the first pressure sensor 81 and the second pressure sensor 82 in the sensor assembly, and subtracts the maximum load pressure detected by the first pressure sensor 81 from the pump outlet pressure detected by the second pressure sensor 82 to obtain the system actual differential pressure. Set the valve target differential pressure to the system actual differential pressure. Send a PWM signal from the control unit 1 to the second proportional pressure reducing valve 44 in the pilot hydraulic control unit 4. The second proportional pressure reducing valve 44 outputs a control pressure to the first pressure compensation valve 62 and the second pressure compensation valve 63 in the variable differential pressure load sensing valve assembly, thereby controlling the differential pressure between the front and rear ends of the first throttle port 64 and the second throttle port 65 to be equal to the current actual differential pressure of the system.

[0034] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A variable speed - variable displacement pressure difference controllable valve front - compensated load - sensing system, characterized in that It includes a control unit, a drive motor assembly, a variable differential pressure load sensing pump assembly, a variable differential pressure load sensing valve assembly, a pilot hydraulic control unit, a pilot handle assembly, an actuator assembly, a sensor assembly, and a motor speed control module, where: The drive motor assembly is used to drive the variable differential pressure load sensing pump assembly to operate, so that the variable differential pressure load sensing pump assembly outputs high-pressure hydraulic oil to the variable differential pressure load sensing valve assembly; the variable differential pressure load sensing valve assembly is configured to regulate the flow rate entering the actuator assembly to drive the actuator assembly to operate; The pilot hydraulic control unit is connected to the input end of the pilot handle assembly, the variable differential pressure load sensing pump assembly, and the variable differential pressure load sensing valve assembly to provide set pressures for the pilot handle assembly, the variable differential pressure load sensing pump assembly, and the variable differential pressure load sensing valve assembly respectively; The output end of the pilot handle assembly is connected to the variable differential pressure load sensing valve assembly, and it is used to output a signal to the variable differential pressure load sensing valve assembly, so that the variable differential pressure load sensing valve assembly controls the target operating speed of the actuator assembly; The sensor assembly is used to detect the maximum load pressure of the system and the outlet pressure of the variable differential pressure load sensing pump assembly; The control unit is electrically connected to the sensor assembly, the motor speed control module, the drive motor assembly, and the pilot hydraulic control unit to collect and process the signals of the sensor assembly and the motor speed control module, and then control the target speed of the drive motor assembly and the control pressure of the pilot hydraulic control unit.

2. The variable speed-variable displacement pressure difference controllable valve front compensation load sensing system according to claim 1, characterized in that The drive motor assembly includes a power supply, a motor driver, and a drive motor. The power supply is electrically connected to the input end of the motor driver, and the output end of the motor driver is electrically connected to the drive motor. The motor driver is configured to receive the target speed signal sent by the control unit and control the drive motor to operate at a speed corresponding to the target speed signal; The output end of the drive motor is mechanically connected to the variable differential pressure load sensing pump assembly coaxially, thereby driving the variable differential pressure load sensing pump assembly to operate.

3. A variable-speed - variable-displacement pressure-difference controllable valve front compensation load sensing system according to claim 1, characterized in that, The variable differential pressure load sensing pump assembly includes a first-stage control valve, a second-stage control valve, a pump displacement regulating valve, and a variable pump; The output end of the first-stage control valve is connected to the input end of the second-stage control valve, the output end of the second-stage control valve is connected to the input end of the pump displacement regulating valve, and the output end of the pump displacement regulating valve is connected to the variable pump; The first-stage control valve is configured to output the actual load sensing differential pressure of the system, and the second-stage control valve is configured to output a flow rate to the pump displacement regulating valve by comparing the actual load sensing differential pressure of the system with the pump target differential pressure, and then regulate the displacement of the variable pump.

4. A variable speed - variable displacement pressure difference controllable valve front - compensated load - sensing system according to claim 3, characterized in that, The pilot hydraulic control unit includes a pilot pump, a pilot relief valve, a first proportional relief valve, and a second proportional relief valve; The pilot overflow valve is arranged at the outlet of the pilot pump and is used to set the primary pilot pressure. The primary pilot pressure is respectively supplied to the input ends of the pilot handle assembly and the first-stage control valve, and is also supplied to the input ends of the first proportional pressure reducing valve and the second proportional pressure reducing valve. The output end of the first proportional pressure reducing valve is connected to the variable differential pressure load sensing pump assembly to provide a set pressure for the pump target differential pressure for the variable differential pressure load sensing pump assembly. The input end of the second proportional pressure reducing valve is connected to the variable differential pressure load sensing valve assembly to provide a set pressure for the valve target differential pressure for the variable differential pressure load sensing valve assembly.

5. A variable speed - variable displacement pressure difference controllable valve front - compensated load - sensing system according to claim 4, characterized in that, The variable differential pressure load sensing valve assembly includes a fixed differential overflow valve, a first pressure compensating valve, a first throttle orifice, a second pressure compensating valve, a second throttle orifice, and a shuttle valve, where: The fixed differential overflow valve is configured at the oil inlet of the variable differential pressure load sensing valve assembly. The first pressure compensating valve is communicated with the oil inlet of the first throttle orifice. The second pressure compensating valve is communicated with the oil inlet of the second throttle orifice. The shuttle valve is communicated with the oil outlets of the first throttle orifice and the second throttle orifice. The input ends of the first throttle orifice and the second throttle orifice are connected to the output end of the pilot handle assembly. One end of the spools of the first pressure compensating valve and the second pressure compensating valve respectively acts on the front-end pressure of the first throttle orifice and the second throttle orifice, and the other ends respectively act on the load pressure and the target control pressure at the rear ends of the first throttle orifice and the second throttle orifice. The target control pressure oil circuits of the first pressure compensating valve and the second pressure compensating valve are in parallel and are connected to the valve target differential pressure output by the pilot hydraulic control unit. The first pressure compensating valve and the second pressure compensating valve are configured to respectively maintain the pressure difference between the front and rear ends of the first throttle orifice and the pressure difference between the front and rear ends of the second throttle orifice at the valve target differential pressure of the variable differential pressure load sensing valve regulated by the second proportional pressure reducing valve in the pilot hydraulic control unit. The first throttle orifice and the second throttle orifice are configured to control the operating speed of the actuator assembly by adjusting the flow area. The fixed differential overflow valve is used to prevent the system from overpressure. The shuttle valve is used to obtain the maximum load pressure of the actuator drive chambers of each branch.

6. A variable speed - variable displacement pressure difference controllable valve front - compensated load - sensing system according to claim 5, characterized in that, One end of the spool of the first-stage control valve acts on the maximum load pressure obtained by the shuttle valve and the actual load sensing differential pressure of the system output by the first-stage control valve, and the other end of the spool acts on the outlet pressure of the variable pump. The input end of the first-stage control valve is connected to the primary pilot pressure port of the pilot hydraulic control unit to realize that the output of the first-stage control valve is the actual load sensing differential pressure of the system. One end of the spool of the second-stage control valve acts on the actual load sensing differential pressure of the system output by the first-stage control valve, and the other end of the spool acts on the pump target differential pressure output by the first proportional pressure reducing valve in the pilot hydraulic control unit. By comparing the pressure difference at both ends of the spool, the displacement of the variable differential pressure load sensing pump is adjusted. The displacement of the variable differential pressure load sensing pump assembly is configured to be controlled by the pump target differential pressure of the pilot hydraulic control unit. When the actual load sensing differential pressure of the system is greater than the pump target differential pressure, the pump displacement decreases. When the actual load sensing differential pressure of the system is less than the pump target differential pressure, the pump displacement increases.

7. The variable speed-variable displacement pressure difference controllable valve front compensation load sensing system according to claim 5, characterized in that, The actuator assembly includes a first actuator and a second actuator. The first actuator is connected to the output port of the first throttle port, and the second actuator is connected to the output port of the second throttle port.

8. A variable-speed - variable-displacement pressure-difference controllable valve front compensation load sensing system according to claim 1, characterized in that, The sensor assembly includes a first pressure sensor and a second pressure sensor. The first pressure sensor is configured on the variable differential pressure load sensing valve assembly. The first pressure sensor is used to detect the maximum load pressure of the system. The second pressure sensor is configured on the connecting pipeline between the variable differential pressure load sensing pump assembly and the variable differential pressure load sensing valve assembly. The second pressure sensor is used to detect the outlet pressure of the variable differential pressure load sensing pump assembly.

9. A variable-speed - variable-displacement pressure-difference controllable valve front compensation load sensing system according to claim 5, characterized in that, The pilot handle assembly includes a first pilot handle and a second pilot handle. The input ends of the first pilot handle and the second pilot handle are connected to the pilot hydraulic control unit. The output ends of the first pilot handle and the second pilot handle are respectively connected to the opening control ends of the first throttle port and the second throttle port. The variable differential pressure load sensing valve assembly is configured to control the target operating speed of the actuator assembly according to the output signals of the first pilot handle and the second pilot handle respectively.

10. A method for controlling a variable speed - variable displacement pressure difference controllable valve front - compensated load - sensing system as described in any one of claims 1 - 9, characterized in that, It includes the following steps: S1: Obtain the target speed signal through the motor speed control module and send the signal to the control unit, and set the system target differential pressure to be proportional to the target speed signal; S2: Send a CAN signal to the drive motor assembly through the control unit to make the motor operate at the target speed value; S3: Set the pump target differential pressure to be equal to the system target differential pressure value. Send a PWM signal to the pilot hydraulic control unit through the control unit, and control the pump displacement of the variable differential pressure load sensing pump assembly through the pilot hydraulic control unit; S4: The control unit obtains the sensor information of the sensor assembly and calculates the actual differential pressure of the system. Set the valve target differential pressure to the actual differential pressure of the system. Send a PWM signal to the pilot hydraulic control unit through the control unit, and control the differential pressure of the variable differential pressure load sensing valve assembly through the pilot hydraulic control unit.

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