A variable speed-variable displacement pressure difference controllable valve front compensation load sensing system and control method

Abstract

The present invention provides a variable speed, variable displacement, pressure differential, controllable pre-valve compensation load-sensing system, comprising a control unit, a drive motor assembly, a variable pressure differential load-sensing pump assembly, a variable pressure differential 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. The drive motor assembly drives the variable pressure differential load-sensing pump assembly to supply oil to the variable pressure differential load-sensing valve assembly, thereby driving the actuator assembly. The pilot hydraulic control unit provides a set pressure. The pilot handle assembly outputs a signal to the variable pressure differential load-sensing valve assembly. The sensor assembly detects the system's maximum load pressure and the outlet pressure of the variable pressure differential load-sensing pump assembly. The control unit controls the target speed of the drive motor assembly and the control pressure of the pilot hydraulic control unit. Compared with existing pre-valve compensation load-sensing systems, this system effectively avoids the problem of actuator speed imbalance under flow saturation conditions, significantly improving control performance.

Description

Technical Field

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

[0002] Load-sensing systems achieve excellent multi-actuator control performance through pressure compensation and are widely used in construction machinery such as excavators and cranes. With the increasing electrification of construction machinery, issues such as large installed battery capacity, high costs, and limited battery life have placed stricter demands on the energy efficiency of load-sensing systems. The development of intelligent systems has also placed higher demands on the control performance of load-sensing systems to cope with the complex operating conditions of construction machinery.

[0003] Compared to post-valve load-sensing systems, pre-compensated load-sensing systems offer a more energy-efficient multi-way valve core structure and are more suitable for electric construction machinery. However, this system can experience flow distribution imbalances in the actuators when flow is saturated. Furthermore, traditional load-sensing systems employ conservative valve port differential pressure settings, which are set by a pressure-regulating spring and cannot be dynamically adjusted during operation. This results in significant pressure differential losses across each throttle port, particularly in multi-actuator, compound motion conditions with high flow demands. Furthermore, this fixed pressure differential setting makes it difficult to accommodate the complex and changing demands of construction machinery, such as the delicate operations and rapid, compound motions required.

[0004] In view of this, the applicant filed this application after studying the existing technology. Summary of the Invention

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

[0006] To solve the above technical problems, the present invention provides a variable speed-variable displacement pressure differential controllable valve pre-compensation load-sensing system, comprising a control unit, a drive motor assembly, a variable pressure differential load-sensing pump assembly, a variable pressure differential 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:

[0007] The drive motor assembly is used to drive the variable pressure differential load-sensing pump assembly to operate, so that the variable pressure differential load-sensing pump assembly outputs high-pressure oil to the variable pressure differential load-sensing valve assembly; the variable pressure differential load-sensing valve assembly is configured to regulate the flow entering the actuator assembly to drive the actuator assembly to operate;

[0008] The pilot hydraulic control unit is connected to the input end of the pilot handle assembly, the variable pressure differential load sensing pump assembly and the variable pressure differential load sensing valve assembly to provide set pressures to the pilot handle assembly, the variable pressure differential load sensing pump assembly and the variable pressure differential load sensing valve assembly respectively;

[0009] The output end of the pilot handle assembly is connected to the variable pressure differential load sensing valve assembly, and is used to output a signal to the variable pressure differential load sensing valve assembly so that the variable pressure differential load sensing valve assembly controls the target operating speed of the actuator assembly;

[0010] 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;

[0011] 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 signals from the sensor assembly and the motor speed control module, thereby controlling the target speed of the drive motor assembly and the control pressure of the pilot hydraulic control unit.

[0012] 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;

[0013] The output end of the driving motor is coaxially mechanically connected to the variable pressure differential load-sensing pump assembly, thereby driving the variable pressure differential load-sensing pump assembly to operate.

[0014] 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;

[0015] 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;

[0016] The first-stage control valve is configured to output the actual load-sensitive pressure difference 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-sensitive pressure difference of the system with the pump target pressure difference, thereby adjusting the displacement of the variable pump.

[0017] As a further optimization, the pilot hydraulic control unit includes a pilot pump, a pilot relief valve, a first proportional pressure reducing valve and a second proportional pressure reducing valve;

[0018] The pilot relief valve is arranged at the outlet of the pilot pump and is used to adjust the primary pilot pressure. The primary pilot pressure is supplied to the pilot handle assembly and the input end of 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.

[0019] The output end of the first proportional pressure reducing valve is connected to the variable pressure differential load-sensitive pump assembly to provide the variable pressure differential load-sensitive pump assembly with a set pressure of the pump target pressure differential, and the input end of the second proportional pressure reducing valve is connected to the variable pressure differential load-sensitive valve assembly to provide the variable pressure differential load-sensitive valve assembly with a set pressure of the valve target pressure differential.

[0020] As a further optimization, the variable pressure differential load-sensing valve assembly includes a fixed differential relief valve, a first pressure compensating valve, a first throttle port, a second pressure compensating valve, a second throttle port, and a shuttle valve, wherein:

[0021] The fixed differential relief valve is arranged at the oil inlet of the variable pressure differential load-sensing valve assembly, the first pressure compensating valve is communicated with the oil inlet of the first throttle port, the second pressure compensating valve is communicated with the oil inlet of the second throttle port, the shuttle valve is communicated with the oil outlets of the first throttle port and the second throttle port, and the input end of the first throttle port and the input end of the second throttle port are connected to the output end of the pilot handle assembly;

[0022] One end of the valve core of the first pressure compensating valve and the second pressure compensating valve acts on the pressure at the front end of the first throttle port and the second throttle port, respectively, and the other end acts on the load pressure and target control pressure at the rear end of the first throttle port and the second throttle port, respectively. The target control pressure oil circuits of the first pressure compensating valve and the second pressure compensating valve are connected in parallel and are connected to the valve target pressure difference output by the pilot hydraulic control unit;

[0023] 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 opening and the pressure difference between the front and rear ends of the second throttle opening at the valve target pressure difference of the variable pressure differential load sensing valve controlled by the second proportional pressure reducing valve in the pilot hydraulic control unit;

[0024] The first throttle opening and the second throttle opening are configured to control the operating speed of the actuator assembly by adjusting the flow area;

[0025] The fixed differential relief valve is used to prevent system overpressure;

[0026] The shuttle valve is used to obtain the maximum load pressure of the drive chamber of each branch actuator.

[0027] As a further optimization, one end of the valve core of the first-stage control valve acts on the maximum load pressure obtained by the shuttle valve and the actual load-sensitive pressure difference of the system output by the first-stage control valve, and the other end of the valve core 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 that the output of the first-stage control valve is the actual load-sensitive pressure difference of the system;

[0028] One end of the valve core of the second-stage control valve acts on the actual load-sensitive pressure differential of the system output by the first-stage control valve, and the other end of the valve core acts on the pump target pressure differential output by the first proportional pressure reducing valve in the pilot hydraulic control unit. The displacement of the variable pressure differential load-sensitive pump is adjusted by comparing the pressure differential across the valve core.

[0029] The displacement of the variable pressure differential load-sensing pump assembly is configured to be controlled by the pump target pressure differential of the pilot hydraulic control unit. When the actual load-sensitive pressure differential of the system is greater than the pump target pressure differential, the pump displacement is reduced; when the actual load-sensitive pressure differential of the system is less than the pump target pressure differential, the pump displacement is increased.

[0030] 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.

[0031] 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 differential load-sensitive 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 pressure differential load-sensitive pump assembly and the variable pressure differential load-sensitive valve assembly. The second pressure sensor is used to detect the outlet pressure of the variable pressure differential load-sensitive pump assembly.

[0032] 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, and 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, and the variable pressure differential 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.

[0033] The present application further provides a method for controlling any of the above-mentioned variable speed-variable displacement pressure differential controllable valve pre-compensation load-sensing systems, comprising the following steps:

[0034] S1: Obtaining a target speed signal through the motor speed control module and sending the signal to the control unit, setting the system target pressure difference to be proportional to the target speed signal;

[0035] S2: Sending a CAN signal to the drive motor assembly through the control unit to make the motor run at the target speed value;

[0036] S3: setting the pump target differential pressure to be equal to the system target differential pressure value, sending a PWM signal to the pilot hydraulic control unit through the control unit, and controlling the pump displacement of the variable differential pressure load-sensing pump assembly through the pilot hydraulic control unit;

[0037] 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.

[0038] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0039] 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.

[0040] 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

[0041] 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.

[0042] 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;

[0043] 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

[0044] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection 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 invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] Example

[0046] See also Figure 1 The present invention provides a variable speed-variable displacement pressure differential controllable valve pre-compensation load-sensing system, comprising a control unit 1, a drive motor assembly 2, a variable pressure differential load-sensing pump assembly 3, a variable pressure differential 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; wherein:

[0047] The drive motor assembly 2 is used to drive the variable pressure differential load-sensing pump assembly 3 to operate, so that the variable pressure differential load-sensing pump assembly 3 outputs high-pressure oil to the variable pressure differential load-sensing valve assembly 6. The variable pressure differential load-sensing valve assembly 6 is configured to regulate the flow entering the actuator assembly 7 to drive the actuator assembly 7 to operate;

[0048] The pilot hydraulic control unit 4 is connected to the input end of the pilot handle assembly 5, the variable pressure differential load sensing pump assembly 3 and the variable pressure differential load sensing valve assembly 6 to provide set pressures to the pilot handle assembly 5, the variable pressure differential load sensing pump assembly 3 and the variable pressure differential load sensing valve assembly 6 respectively;

[0049] The output end of the pilot handle assembly 5 is connected to the variable pressure differential load sensing valve assembly 6, and is used to output a signal to the variable pressure differential load sensing valve assembly 6, so that the variable pressure differential load sensing valve assembly 6 controls the target operating speed of the actuator assembly 7;

[0050] The sensor assembly 8 is used to detect the maximum load pressure of the system and the outlet pressure of the variable differential pressure load-sensing pump assembly;

[0051] 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 signals from the sensor assembly 8 and the motor speed control module 9, thereby controlling the target speed of the drive motor assembly 2 and the control pressure of the pilot hydraulic control unit 4.

[0052] The motor speed control module 9 is used to provide a target speed signal, which can be given by the driver according to the speed knob and the working mode button, or can be automatically controlled by intelligently identifying the real-time working conditions of the construction machinery.

[0053] In this embodiment, when the system is operating normally, the pump displacement changes in real time to maintain the system's actual pressure differential at the system's target pressure differential. When the system enters flow saturation, the pump displacement reaches its maximum, and the system's actual pressure differential will decrease, causing the valve's target pressure differential to decrease synchronously, resulting in a decrease in the flow demand under the current flow area of ​​each throttle port. When the total flow demand drops to equal the pump output flow, the system's actual pressure differential and the valve's target pressure differential stop decreasing and remain constant, reaching a new equilibrium state. During this process, the pump's target pressure differential is the system's target pressure differential, which is always greater than the system's actual pressure differential, so the pump displacement always remains at its maximum value. Furthermore, when the flow area of ​​each main valve core of the system decreases, the system's actual pressure differential will rise, causing the valve's target pressure differential to rise synchronously. When the system's actual pressure differential rises to equal the system's target pressure differential, the pump displacement will show a downward trend to maintain the system's actual pressure differential at the system's target pressure differential. At this point, the system exits the flow saturation state. Therefore, the system achieves good anti-flow saturation function by actively regulating the valve target pressure difference. Compared with the existing pre-valve compensation load-sensitive system, it effectively avoids the actuator speed imbalance problem under flow saturation conditions and significantly improves the control performance.

[0054] 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.

[0055] 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 coaxially mechanically connected to the variable pressure differential load sensing pump assembly 3.

[0056] The motor driver 22 is configured to receive a target speed signal sent by the control unit 1 and control the drive motor 23 to run at a speed corresponding to the target speed signal.

[0057] Specifically, the variable differential pressure load-sensing 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, and the output end of the pump displacement regulating valve 32 is connected to the variable pump 34.

[0058] The first-stage control valve 33 is configured to output the actual load-sensitive pressure difference of the system, and the second-stage control valve 31 is configured to output flow to the pump displacement regulating valve 32 by comparing the actual load-sensitive pressure difference of the system with the pump target pressure difference, thereby adjusting the pump displacement.

[0059] Furthermore, 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 and is used to adjust the primary pilot pressure, which is supplied to the pilot handle assembly 5 and the input end of the first-stage control valve 33 of the variable pressure differential load-sensing pump assembly 3, respectively, and is also supplied to the input ends of the first proportional pressure-reducing valve 43 and the second proportional pressure-reducing valve 44;

[0060] Among them, the output end of the first proportional pressure reducing valve 43 is connected to the variable pressure differential load-sensitive pump assembly 3, so as to provide the variable pressure differential load-sensitive pump assembly 3 with a set pressure of the pump target pressure difference, and the input end of the second proportional pressure reducing valve 44 is connected to the variable pressure differential load-sensitive valve assembly 6, so as to provide the variable pressure differential load-sensitive valve assembly 6 with a set pressure of the valve target pressure difference.

[0061] Furthermore, the variable differential pressure load-sensing 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 arranged at the oil inlet of the variable differential pressure load-sensing valve assembly 6, the first pressure compensating valve 62 is arranged at the oil inlet of the first throttle port 64, the second pressure compensating valve 63 is arranged at the oil inlet of the second throttle port 65, and the shuttle valve 66 is arranged at the oil outlets of the first throttle port 64 and the second throttle port 65. The input end of the first throttle port 64 and the input end of the second throttle port 65 are connected to the output end of the pilot handle assembly 5.

[0062] One end of the valve core of the first pressure compensating valve 62 and the second pressure compensating valve 63 acts on the pressure at the front end of the first throttle port 64 and the second throttle port 65, respectively, and the other end acts on the load pressure and target control pressure at the rear end of the first throttle port 64 and the second throttle port 65, respectively. The target control pressure oil circuits of the first pressure compensating valve 62 and the second pressure compensating valve 63 are connected in parallel and connected to the valve target pressure difference output by the pilot hydraulic control unit 4;

[0063] The first pressure compensating valve 62 and the second pressure compensating valve 63 are configured to respectively maintain the pressure difference between the front and rear ends of the first throttle opening 64 and the pressure difference between the front and rear ends of the second throttle opening 65 at the valve target pressure difference of the variable pressure differential load sensing valve controlled by the second proportional pressure reducing valve 44 in the pilot hydraulic control unit 4;

[0064] The first throttle opening 64 and the second throttle opening 65 are configured to control the operating speed of the actuator assembly 7 by adjusting the flow area of ​​the oil;

[0065] The differential relief valve 61 is used to prevent the system from over-pressurizing;

[0066] The shuttle valve 66 is used to obtain the maximum load pressure of the drive chamber of each branch actuator.

[0067] Furthermore, one end of the valve core of the first-stage control valve 33 acts on the maximum load pressure obtained by the shuttle valve 66 and the actual load-sensitive pressure difference of the system output by the first-stage control valve 33, and the other end of the valve core 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 that the output of the first-stage control valve 33 is the actual load-sensitive pressure difference of the system;

[0068] The second-stage control valve 31 has one end of the valve core acting on the actual system load-sensitive pressure difference output by the first-stage control valve 33, and the other end of the valve core acting 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 difference across the valve core, the displacement of the variable pressure differential load-sensitive pump is adjusted.

[0069] The displacement of the variable pressure differential load-sensing pump assembly 3 is configured to be controlled by the pump target pressure differential of the pilot hydraulic control unit 4. When the actual load-sensitive pressure differential of the system is greater than the pump target pressure differential, the pump displacement is reduced. When the actual load-sensitive pressure differential of the system is less than the pump target pressure differential, the pump displacement is increased.

[0070] 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. The first actuator 71 and the second actuator 72 are hydraulic cylinders or hydraulic motors.

[0071] 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 differential load-sensitive 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 differential load-sensitive pump assembly 3 and the variable pressure differential load-sensitive valve assembly 6. The second pressure sensor 82 is used to detect the outlet pressure of the variable pressure differential load-sensitive pump assembly 3.

[0072] 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, and the output ends of the first pilot handle 51 and the second pilot handle 52 are connected to the opening control end of the throttle port in the variable pressure differential load sensitive valve assembly 6, and the variable pressure differential load sensitive valve assembly 6 is configured to control the target operating speeds of the first actuator 71 and the second actuator 72 according to the output signals of the first pilot handle 51 and the second pilot handle 52, respectively.

[0073] refer to Figure 2 As shown, a control method of a variable speed-variable displacement pressure difference controllable valve front compensation load sensing system of the present application is as follows:

[0074] S1: Obtain a target speed signal through the motor speed control module 9 and send the signal to the control unit 1, setting the system target pressure difference to be proportional to the target speed signal;

[0075] S2: Sending a CAN signal to the drive motor assembly 2 through the control unit 1 to make the motor run at a target speed value;

[0076] S3: The pump target pressure difference is set to be equal to the system target pressure difference value, and the control unit 1 sends a PWM signal to the first proportional pressure reducing valve 43 in the pilot hydraulic control unit 4. The first proportional pressure reducing valve 43 outputs the control pressure to the second stage control valve 31 in the variable pressure differential load sensing pump assembly 3, thereby controlling the pump displacement;

[0077] 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 actual pressure difference of the system, and sets the valve target pressure difference to the actual pressure difference of the system. The control unit 1 sends a PWM signal to the second proportional pressure reducing valve 44 in the pilot hydraulic control unit 4, and the second proportional pressure reducing valve 44 outputs the control pressure to the first pressure compensation valve 62 and the second pressure compensation valve 63 in the variable pressure differential load sensitive valve assembly, thereby controlling the front and rear end pressure difference of the first throttle port 64 and the second throttle port 65 to be equal to the current actual pressure difference of the system.

[0078] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A variable speed-variable displacement pressure difference controllable valve front compensation load sensitive system, characterized in that: It includes a control unit, a drive motor assembly, a variable pressure differential load sensing pump assembly, a variable pressure differential 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 differential load-sensing pump assembly to operate, so that the variable pressure differential load-sensing pump assembly outputs high-pressure oil to the variable pressure differential load-sensing valve assembly; the variable pressure differential load-sensing valve assembly is configured to regulate the flow 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 pressure differential load sensing pump assembly and the variable pressure differential load sensing valve assembly to provide set pressures to the pilot handle assembly, the variable pressure differential load sensing pump assembly and the variable pressure differential load sensing valve assembly respectively; The output end of the pilot handle assembly is connected to the variable pressure differential load sensing valve assembly, and is used to output a signal to the variable pressure differential load sensing valve assembly so that the variable pressure differential 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 signals from the sensor assembly and the motor speed control module, thereby controlling the target speed of the drive motor assembly and the control pressure of the pilot hydraulic control unit; 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-sensitive pressure difference 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-sensitive pressure difference of the system with the pump target pressure difference, thereby adjusting the displacement of the variable pump.

2. A variable speed-variable displacement pressure differential 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, wherein the power supply is electrically connected to an input terminal of the motor driver, and an output terminal of the motor driver is electrically connected to the drive motor, and the motor driver is configured to receive a 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 driving motor is coaxially mechanically connected to the variable pressure differential load-sensing pump assembly, thereby driving the variable pressure differential load-sensing pump assembly to operate.

3. The variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to claim 1, characterized in that: The pilot hydraulic control unit includes a pilot pump, a pilot relief valve, a first proportional pressure reducing valve and a second proportional pressure reducing valve; The pilot relief valve is arranged at the outlet of the pilot pump and is used to adjust the primary pilot pressure. The primary pilot pressure is supplied to the pilot handle assembly and the input end of 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 pressure differential load-sensitive pump assembly to provide the variable pressure differential load-sensitive pump assembly with a set pressure of the pump target pressure differential, and the input end of the second proportional pressure reducing valve is connected to the variable pressure differential load-sensitive valve assembly to provide the variable pressure differential load-sensitive valve assembly with a set pressure of the valve target pressure differential.

4. The variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to claim 3, characterized in that: The variable pressure differential load-sensing valve assembly includes a fixed differential relief valve, a first pressure compensating valve, a first throttle port, a second pressure compensating valve, a second throttle port, and a shuttle valve, wherein: The fixed differential relief valve is arranged at the oil inlet of the variable pressure differential load-sensing valve assembly, the first pressure compensating valve is communicated with the oil inlet of the first throttle port, the second pressure compensating valve is communicated with the oil inlet of the second throttle port, the shuttle valve is communicated with the oil outlets of the first throttle port and the second throttle port, and the input end of the first throttle port and the input end of the second throttle port are connected to the output end of the pilot handle assembly; One end of the valve core of the first pressure compensating valve and the second pressure compensating valve acts on the pressure at the front end of the first throttle port and the second throttle port, respectively, and the other end acts on the load pressure and target control pressure at the rear end of the first throttle port and the second throttle port, respectively. The target control pressure oil circuits of the first pressure compensating valve and the second pressure compensating valve are connected in parallel and are connected to the valve target pressure difference 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 opening and the pressure difference between the front and rear ends of the second throttle opening at the valve target pressure difference of the variable pressure differential load sensing valve controlled by the second proportional pressure reducing valve in the pilot hydraulic control unit; The first throttle opening and the second throttle opening are configured to control the operating speed of the actuator assembly by adjusting the flow area; The fixed differential relief valve is used to prevent system overpressure; The shuttle valve is used to obtain the maximum load pressure of the drive chamber of each branch actuator.

5. The variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to claim 4, characterized in that: One end of the valve core of the first-stage control valve acts on the maximum load pressure obtained by the shuttle valve and the actual load-sensitive pressure difference of the system output by the first-stage control valve, and the other end of the valve core 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 that the output of the first-stage control valve is the actual load-sensitive pressure difference of the system; One end of the valve core of the second-stage control valve acts on the actual load-sensitive pressure differential of the system output by the first-stage control valve, and the other end of the valve core acts on the pump target pressure differential output by the first proportional pressure reducing valve in the pilot hydraulic control unit. The displacement of the variable pressure differential load-sensitive pump is adjusted by comparing the pressure differential across the valve core. The displacement of the variable pressure differential load-sensing pump assembly is configured to be controlled by the pump target pressure differential of the pilot hydraulic control unit. When the actual load-sensitive pressure differential of the system is greater than the pump target pressure differential, the pump displacement is reduced; when the actual load-sensitive pressure differential of the system is less than the pump target pressure differential, the pump displacement is increased.

6. The variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to claim 4, 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.

7. The variable speed-variable displacement pressure differential 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 pressure differential load-sensitive 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 pressure differential load-sensitive pump assembly and the variable pressure differential load-sensitive valve assembly. The second pressure sensor is used to detect the outlet pressure of the variable pressure differential load-sensitive pump assembly.

8. The variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to claim 4, 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, and 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, and the variable pressure differential 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.

9. A method for controlling a variable speed-variable displacement pressure differential controllable valve front compensation load sensing system according to any one of claims 1 to 8, characterized in that: The steps include: S1: Obtaining a target speed signal through the motor speed control module and sending the signal to the control unit, setting the system target pressure difference to be proportional to the target speed signal; S2: Sending a CAN signal to the drive motor assembly through the control unit to make the motor run at the target speed value; S3: setting the pump target differential pressure to be equal to the system target differential pressure value, sending a PWM signal to the pilot hydraulic control unit through the control unit, and controlling 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 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.

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