An electro-hydraulic composite cylinder is applied to a distributed hydraulic system of an electric loader

Abstract

The application provides an electric loader distributed hydraulic system using an electro-hydraulic composite cylinder. Mainly includes steering drive subsystem, first pumping device, bucket distributed valve group, bucket electro-hydraulic composite cylinder, second sending device, boom distributed valve group, boom electro-hydraulic composite cylinder, whole vehicle controller, control handle, steering wheel, proportional electromagnetic on-off valve and hydraulic accumulator. By decoupling the steering, boom and bucket devices of the traditional loader, independent and efficient driving of each part is realized. The bypass throttling loss is effectively reduced, the overall machine efficiency is greatly improved, each actuator is not disturbed, the system control difficulty is reduced, the response time is shortened, and the control performance is enhanced. The advantages of electric drive and hydraulic drive are effectively combined, and the performance requirements of the overall vehicle economy and power are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of excavation engineering machinery system structures, and in particular to a distributed hydraulic system for an electric loader using an electro-hydraulic composite cylinder. Background Art

[0002] Electric loaders with zero emissions, high efficiency and low noise have good development prospects. However, traditional electric loaders simply transplant the three-electric technology of new energy vehicles, which only improves the efficiency of the power source part. The rear-end hydraulic system still uses the traditional configuration (multi-way valve distribution method), resulting in low energy efficiency of the whole machine, unable to give full play to the advantages of electro-hydraulic composite transmission, and the limitations of the transmission cylinder. Based on this background, research on the electro-hydraulic composite drive system of electric loaders is carried out. Summary of the Invention

[0003] The present invention provides a distributed hydraulic system for an electric loader using an electro-hydraulic composite cylinder. The system is suitable for loaders with large load fluctuations and complex and harsh working environments, so as to enhance the controllability of the loader's working device and thereby improve the energy utilization rate of the entire machine, thereby improving at least one of the above-mentioned technical problems.

[0004] In order to solve the above technical problems, the present invention provides a distributed hydraulic system for an electric loader using an electro-hydraulic compound cylinder, including an electric loader distributed hydraulic system body, which includes: a steering drive subsystem, a first pumping device, a second pumping device, a bucket distributed valve group, a bucket electro-hydraulic compound cylinder, a boom distributed valve group, an arm electro-hydraulic compound cylinder, a vehicle controller, a control handle, a steering wheel, a proportional solenoid switch valve and a hydraulic accumulator.

[0005] The bucket distributed valve group is composed of a first bucket electromagnetic switch valve, a second bucket electromagnetic switch valve, a third bucket electromagnetic switch valve, a fourth bucket electromagnetic switch valve, and a fifth bucket electromagnetic switch valve; and is connected to the bucket electro-hydraulic composite cylinder and the first pumping device to form a bucket subsystem, and the first pumping device is connected to the oil tank;

[0006] The boom distributed valve group is composed of a first boom solenoid switch valve, a second boom solenoid switch valve, a third boom solenoid switch valve, a fourth boom solenoid switch valve, and a fifth boom solenoid switch valve; and is connected to the boom electro-hydraulic composite cylinder and the second pumping device to form a boom subsystem, and the second pumping device is connected to the oil tank;

[0007] The boom electro-hydraulic composite cylinder is connected to the hydraulic accumulator via a proportional electromagnetic switch valve;

[0008] The main body is connected and controlled by the vehicle controller using a CAN network low-voltage wiring harness;

[0009] Wherein, the vehicle controller is configured as follows:

[0010] It can control the steering drive subsystem based on the steering wheel signal; it can also switch the drive mode of the bucket subsystem and the boom subsystem based on the control handle signal, including electric drive, hydraulic drive or electro-hydraulic composite drive.

[0011] The steering drive subsystem includes a first motor controller, a first motor, a first fixed displacement pump, a relief valve, a one-way valve, a left steering cylinder and a right steering cylinder;

[0012] The first pumping device includes a second motor controller, a second motor and a first variable displacement pump;

[0013] The second pumping device includes a third motor controller, a third motor and a second variable displacement pump;

[0014] Among them, the first motor is mechanically connected to the first fixed displacement pump; the second motor is mechanically connected to the first variable displacement pump; the third motor is mechanically connected to the second variable displacement pump; the fourth motor is mechanically connected to the first coupler; the first coupler is mechanically connected to the bucket compound cylinder; the fifth motor is mechanically connected to the second coupler; the second coupler is mechanically connected to the left boom compound cylinder and the right boom compound cylinder respectively; the first fixed displacement pump is connected to the hydraulic pipeline of the overflow valve; the first fixed displacement pump is connected to the hydraulic pipeline of the check valve; the first fixed displacement pump is connected to the hydraulic pipeline of the left steering cylinder and the right steering cylinder; the first variable displacement pump is connected to the hydraulic pipeline of the bucket distributed valve group; the bucket distributed valve group is connected to the hydraulic pipeline of the bucket compound cylinder; the second variable displacement pump is connected to the hydraulic pipeline of the boom distributed valve group; the boom distributed valve group is connected to the hydraulic pipeline of the left boom compound cylinder and the right boom compound cylinder respectively; the rodless chambers of the left boom compound cylinder and the right boom compound cylinder are respectively connected to the hydraulic pipelines of the proportional solenoid switch valve; the proportional solenoid switch valve is connected to the hydraulic pipeline of the hydraulic accumulator;

[0015] The first motor controller is connected to the high-voltage wiring harness of the first motor; the second motor controller is connected to the high-voltage wiring harness of the second motor; the third motor controller is connected to the high-voltage wiring harness of the third motor; the fourth motor controller is connected to the high-voltage wiring harness of the fourth motor; and the fifth motor controller is connected to the high-voltage wiring harness of the fifth motor.

[0016] Among them, the first motor controller is connected to the high-voltage wiring harness of the first motor; the second motor controller is connected to the high-voltage wiring harness of the second motor; the third motor controller is connected to the high-voltage wiring harness of the third motor; the fourth motor controller is connected to the high-voltage wiring harness of the fourth motor; the fifth motor controller is connected to the high-voltage wiring harness of the fifth motor; the vehicle controller is respectively connected to the first motor controller, the second motor controller, the first variable pump, the third motor controller, the second variable pump, the control handle, the steering wheel, the first bucket solenoid switch valve, the second bucket solenoid switch valve, the third bucket solenoid switch valve, the fourth bucket solenoid switch valve, the fifth bucket solenoid switch valve, the first arm solenoid switch valve, the second arm solenoid switch valve, the third arm solenoid switch valve, the fourth arm solenoid switch valve, the fifth arm solenoid switch valve and the proportional solenoid switch valve through the CAN network low-voltage wiring harness.

[0017] As a further optimization, in the bucket distributed valve group, the first bucket solenoid switch valve and the second bucket solenoid switch valve are respectively connected to the oil outlet of the first variable pump, and are also connected to the bucket compound cylinder; the fourth bucket solenoid switch valve and the fifth bucket solenoid switch valve are respectively connected to the bucket compound cylinder and are also connected to the oil tank; the third bucket solenoid switch valve is used to connect the rod chamber and the rodless chamber of the bucket compound cylinder.

[0018] As a further optimization, in the boom distributed valve group, the first boom solenoid switch valve is respectively connected to the oil outlet of the second variable pump and the rod chamber of the left boom compound cylinder and the right boom compound cylinder; the second boom solenoid switch valve is respectively connected to the oil outlet of the second variable pump and the rodless chamber of the left boom compound cylinder and the right boom compound cylinder; the fourth boom solenoid switch valve and the fifth boom solenoid switch valve are respectively connected to the left boom compound cylinder, the right boom compound cylinder and the oil tank to allow the oil to flow back to the oil tank; the third boom solenoid switch valve is used to connect the rod chamber and the rodless chamber of the left boom compound cylinder and the right boom compound cylinder.

[0019] As a further optimization, in the electric drive part of the bucket electro-hydraulic composite cylinder, the fourth motor is used as the drive, and the speed is reduced through the first coupler, and then the rotation can be converted into linear motion through the roller screw.

[0020] As a further optimization, in the electric drive part of the boom electro-hydraulic composite cylinder, the fifth motor is used as the drive, and the speed is reduced through the second coupler, so that the rotation can be converted into linear motion through the roller screw.

[0021] As a further optimization, the main body also has an energy recovery mode. When energy recovery is performed, the vehicle controller is configured to dynamically allocate electrical energy recovery and hydraulic energy recovery paths according to the battery SOC and hydraulic accumulator SOC values.

[0022] Wherein, during energy recovery, the bucket electro-hydraulic composite cylinder can convert mechanical energy into electrical energy through the fourth motor in the generator working condition to recover energy; the boom electro-hydraulic composite cylinder can convert mechanical energy into electrical energy through the fifth motor in the generator working condition to recover energy, and can also recover hydraulic energy through the hydraulic accumulator.

[0023] Wherein, the vehicle controller can receive the steering wheel control signal, and adopt pump-controlled steering, that is, the first motor drives the first variable pump to output the oil cylinder, and pushes the steering oil cylinder to complete the vehicle steering.

[0024] Wherein, the vehicle controller receives the signal of the control handle to determine the driving mode, when the driving mode is economic, the bucket electro-hydraulic composite cylinder and the boom electro-hydraulic composite cylinder adopt separate electric drive driving, that is, the fourth motor rotates through the first coupler for deceleration, and then converts into linear actuation through the roller screw; the fifth motor rotates through the second coupler for deceleration, and then converts into linear actuation through the roller screw. In this way, the advantages of high electric drive efficiency, fast response and high precision are realized. At the same time, in order to meet the thrust demand, when the output torque of the motor in the bucket electro-hydraulic composite cylinder and the boom electro-hydraulic composite cylinder reaches the rated torque, the hydraulic drive starts to work to assist the movement of the bucket and the oil cylinder.

[0025] Further, when the driving mode is power, the bucket electro-hydraulic composite cylinder and the boom electro-hydraulic composite cylinder simultaneously provide power through electro-hydraulic composite driving.

[0026] Wherein, the boom electro-hydraulic composite cylinder can convert mechanical energy into electrical energy through the fourth motor in the generator working condition to recover energy under stable working conditions, and can recover energy through the hydraulic accumulator under instantaneous strong impact. The advantages of stable electric energy recovery, high energy recovery efficiency and good hydraulic energy recovery instantaneous energy recovery are fully utilized. When the SOC of the battery or the SOC of the hydraulic accumulator reaches 95% or more, energy recovery is stopped, and energy recovery is performed by the other side. When the SOC of both reaches 95% or more, energy recovery is not performed.

[0027] As a further optimization, the variable pump in the system is one of an axial piston variable pump, a radial piston variable pump, a screw variable pump or a vane variable pump.

[0028] As a further optimization, the fixed displacement pump in the system is one of a gear fixed displacement pump, a piston fixed displacement pump or a screw fixed displacement pump.

[0029] By adopting the above technical solutions, the following technical effects can be achieved:

[0030] 1. The boom and the bucket are driven by electro-hydraulic composite cylinders, effectively combining the advantages of high electric drive efficiency, fast response, good stable energy recovery performance, good hydraulic drive impact resistance, large thrust, high power density and good instantaneous energy recovery.

[0031] 2. The hydraulic system adopts a distributed configuration, decoupling the three execution ends of the electric loader's steering, boom, and bucket, and adopts an independent pump-valve coordinated control system to achieve on-demand system flow supply, effectively eliminating bypass throttling losses and improving the transmission efficiency of the hydraulic system.

[0032] 3. The bucket and boom adopt a five-valve independent inlet and outlet control system to achieve decoupling control of the oil inlet and return chambers and provide energy regeneration conditions. On the one hand, it solves the mutual interference problem during the compound operation of the bucket and boom, and improves the operability and stability of the working device; on the other hand, it greatly reduces the pressure coupling loss and throttling loss existing in the original centralized system.

[0033] The present invention applies a distributed hydraulic system of an electric loader with an electro-hydraulic composite cylinder and combines it with a control strategy, which greatly improves the system energy efficiency, exhibits good control characteristics, and meets the requirements of vehicle power and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 A structural principle diagram of a distributed hydraulic system for an electric loader using an electro-hydraulic composite cylinder according to the present invention.

[0036] Figure 2 A control strategy diagram of a distributed hydraulic system of an electric loader using an electro-hydraulic composite cylinder according to the present invention.

[0037] Markings in the figure: 1. First motor controller; 2. First motor; 3. First fixed displacement pump; 4. Overflow valve; 5. Check valve; 6. Left steering cylinder; 7. Right steering cylinder; 8. Second motor controller; 9. Second motor; 10. First variable displacement pump; 11. Bucket distributed valve group; 12. Bucket electro-hydraulic composite cylinder; 13. Third motor controller; 14. Third motor; 15. Second variable displacement pump; 16. Boom distributed valve group; 17. Boom electro-hydraulic composite cylinder; 18. Vehicle controller; 19. Control handle; 20. Steering wheel; 21. Proportional solenoid switch valve; 22. Hydraulic accumulator; 23. Fuel tank

[0038] 11-1, first bucket electromagnetic switch valve; 11-2, second bucket electromagnetic switch valve; 11-3, third bucket electromagnetic switch valve; 11-4, fourth bucket electromagnetic switch valve; 11-5, fifth bucket electromagnetic switch valve;

[0039] 12-1, fourth motor controller; 12-2, fourth motor; 12-3, first coupler; 12-4, bucket compound cylinder;

[0040] 16-1, first boom electromagnetic switch valve; 16-2, second boom electromagnetic switch valve; 16-3, third boom electromagnetic switch valve; 16-4, fourth boom electromagnetic switch valve; 16-5, fifth boom electromagnetic switch valve;

[0041] 17-1, fifth motor controller; 17-2, fifth motor; 17-3, second coupler; 17-4, left boom compound cylinder; 17-5, right boom compound cylinder. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0043] The following are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the following examples. Any technical solution falling within the concept of the present application falls within the protection scope of the present application.

[0044] As shown in the accompanying drawings of the specification, Figure 1 The present application provides an electric loader distributed hydraulic system applying an electro-hydraulic compound cylinder, which comprises an electric loader distributed hydraulic system body. The body comprises a steering drive subsystem, a first pumping device, a second pumping device, a bucket distributed valve group 11, a bucket electro-hydraulic compound cylinder 12, a boom distributed valve group 16, a boom electro-hydraulic compound cylinder 17, a whole vehicle controller 18, a control handle 19, a steering wheel 20, a proportional electromagnetic switch valve 21, and a hydraulic accumulator 22.

[0045] The steering drive subsystem includes a first motor controller 1, a first motor 2, a first fixed displacement pump 3, a relief valve 4, a check valve 5, a left steering cylinder 6, and a right steering cylinder 7. The first pumping device includes a second motor controller 8, a second motor 9, and a first variable displacement pump 10. The second pumping device includes a third motor controller 13, a third motor 14, and a second variable displacement pump 15.

[0046] The above connection relationships are as follows: the first motor 2 is mechanically connected to the first fixed displacement pump 3; the second motor 9 is mechanically connected to the first variable displacement pump 10; the third motor 14 is mechanically connected to the second variable displacement pump 15; the fourth motor 12-2 is mechanically connected to the first coupler 12-3; the first coupler 12-3 is mechanically connected to the bucket compound cylinder 12-4; the fifth motor 17-2 is mechanically connected to the second coupler 17-3; the second coupler 17-3 is mechanically connected to the left boom compound cylinder 17-4 and the right boom compound cylinder 17-5 respectively; the first fixed displacement pump 3 is connected to the hydraulic pipeline of the overflow valve 4; the first fixed displacement pump 3 is connected to the hydraulic pipeline of the one-way valve 5; the A certain amount of pump 3 is connected to the hydraulic pipelines of the left steering cylinder 6 and the right steering cylinder 7 respectively; the first variable pump 10 is connected to the hydraulic pipeline of the bucket distributed valve group 11; the bucket distributed valve group 11 is connected to the hydraulic pipeline of the bucket compound cylinder 12-4; the second variable pump 15 is connected to the hydraulic pipeline of the boom distributed valve group 16; the boom distributed valve group 16 is connected to the hydraulic pipeline of the left boom compound cylinder 17-4 and the right boom compound cylinder 17-5 respectively; the rodless chambers of the left boom compound cylinder 17-4 and the right boom compound cylinder 17-5 are connected to the hydraulic pipeline of the proportional electromagnetic switch valve 21; the proportional electromagnetic switch valve 21 is connected to the hydraulic pipeline of the hydraulic accumulator 22. The first motor controller 1 is connected to the high-voltage wiring harness of the first motor 2; the second motor controller 8 is connected to the high-voltage wiring harness of the second motor 9; the third motor controller 13 is connected to the high-voltage wiring harness of the third motor 14; the fourth motor controller 12-1 is connected to the high-voltage wiring harness of the fourth motor 12-2; the fifth motor controller 17-1 is connected to the high-voltage wiring harness of the fifth motor 17-2; the vehicle controller 18 is connected to the first motor controller 1, the second motor controller 8, the first variable pump 10, the third motor controller 13, the second variable pump 15, and the control handle respectively. 19. Steering wheel 20, the first bucket solenoid switch valve 11-1, the second bucket solenoid switch valve 11-2, the third bucket solenoid switch valve 11-3, the fourth bucket solenoid switch valve 11-4, the fifth bucket solenoid switch valve 11-5, the first boom solenoid switch valve 16-1, the second boom solenoid switch valve 16-2, the third boom solenoid switch valve 16-3, the fourth boom solenoid switch valve 16-4, the fifth boom solenoid switch valve 16-5, and the proportional solenoid switch valve 21 are connected through a CAN network low-voltage wiring harness for control.

[0047] The electromagnetic switch valve in the bucket distributed valve group 11 and the boom distributed valve group 16 is a two-position two-way proportional valve with throttling control function, which can control the precise control loop pressure and flow.

[0048] The motor in the system can be selected from a permanent magnet synchronous motor, a switched reluctance motor, a direct current motor, an alternating current induction motor and the like.

[0049] The variable pump in the system is an axial plunger variable pump, a radial plunger variable pump, a screw variable pump or a vane variable pump.

[0050] The constant pump in the system is a gear constant pump, a plunger constant pump or a screw constant pump.

[0051] The working principle of the system is as follows:

[0052] The loader driver drives the loader to complete the steering action, the bucket action and the boom action through the control handle 19 and the steering wheel 20, and the steering uses an independent pump system; the vehicle controller 18 can select electric drive driving, hydraulic driving or electro-hydraulic composite driving through the control handle 19 signal and the actuator parameter. The liquid drive part of the loader bucket action and the boom action adopts a five-valve type import and export independent control system, and the electric drive part is rotated through the motor, decelerated through the coupling and finally converted into linear action through the roller screw.

[0053] As shown in Figure 2 The application also provides a control strategy of the electric loader distributed hydraulic system using the electro-hydraulic composite cylinder, as described in the above and the following embodiments.

[0054] Embodiment A

[0055] When the loader is steering, the driver rotates the steering wheel 20 clockwise, the vehicle controller 18 receives the steering wheel 20 signal, sends a control signal to the first motor controller 1, the first motor controller 1 controls the first motor 2 to rotate clockwise, drives the first constant pump 3 to rotate clockwise, delivers hydraulic oil to the rodless chamber of the left steering oil cylinder 6 and the rod chamber of the right steering oil cylinder 7, and at the same time, the hydraulic oil in the rod chamber of the left steering oil cylinder 6 and the rodless chamber of the right steering oil cylinder 7 returns to the oil inlet of the first constant pump 3, and the whole machine follows the driver's operation to steer to the right. When the driver rotates the steering wheel 20 counterclockwise, the vehicle controller 18 receives the steering wheel 20 signal, sends a control signal to the first motor controller 1, the first motor controller 1 controls the first motor 2 to rotate counterclockwise, drives the first constant pump 3 to rotate counterclockwise, delivers hydraulic oil to the rod chamber of the left steering oil cylinder 6 and the rodless chamber of the right steering oil cylinder 7, and at the same time, the hydraulic oil in the rodless chamber of the left steering oil cylinder 6 and the rod chamber of the right steering oil cylinder 7 returns to the oil inlet of the first constant pump 3, and the whole machine follows the driver's operation to steer to the left.

[0056] Example B

[0057] When the loader bucket cylinder extends, the driver controls the control handle 19, and the vehicle controller 18 receives the handle signal to determine the current driving mode. When it is in economic mode, that is, when the demand is economic, the vehicle controller 18 sends a control signal to the fourth motor controller 12-1, and the fourth motor controller 12-1 controls the fourth motor 12-2 to rotate, which is decelerated by the first coupler 12-3 and drives the roller screw to rotate and convert into linear actuation. At this time, if the pure electric drive thrust is insufficient, the hydraulic drive intervenes to assist the output, and the second motor controller 8 controls the second motor 9 to rotate, and the second motor 9 drives the first variable pump 10 to rotate, and the second motor 9 The variable speed is combined with the variable displacement of the first variable displacement pump 10 to supply flow as required to the P ports of the first and second bucket solenoid valves 11-1 and 11-2. At this time, the first bucket solenoid valve 11-1 is in the left position, and the flow is controlled by the throttling device within the valve and delivered to the rodless chamber of the bucket composite cylinder 12-4. Simultaneously, the second, third, and fourth bucket solenoid valves 11-2, 11-3, and 11-4 are all closed, and the fifth bucket solenoid valve 11-5 is in the right position. The throttling device within the valve controls the return of hydraulic oil from the rod chamber of the bucket composite cylinder 12-4 to the oil tank 23. When in power mode, i.e., when power is required, both the electric and hydraulic drives respond simultaneously.

[0058] When the loader bucket oil cylinder retracts, the driver controls the handle 19, the vehicle controller 18 receives the handle signal, judges the current driving mode, when in the economy mode, the vehicle controller 18 sends a control signal to the fourth motor controller 12-1, the fourth motor controller 12-1 controls the fourth motor 12-2 to rotate, and through the first coupler 12-3 to reduce the speed, drives the roller screw to rotate and convert into linear action. At this time, if the pure electric drive thrust is insufficient, the hydraulic drive intervenes to assist the output, the second motor 9 drives the first variable pump 10 to rotate, the second motor 9 changes the speed in combination with the first variable pump 10 to change the displacement, and the flow is supplied to the P port of the first bucket electromagnetic switch valve 11-1 and the second bucket electromagnetic switch valve 11-2 according to the demand. At this time, the second bucket electromagnetic switch valve 11-2 is in the right position and works, controls the flow through the valve throttling device and delivers the flow to the rod cavity of the bucket composite cylinder 12-4, and the first bucket electromagnetic switch valve 11-1, the third bucket electromagnetic switch valve 11-3 and the fifth bucket electromagnetic switch valve 11-5 are all in the closed state, and the fourth bucket electromagnetic switch valve 11-4 is in the left position and works, controls the hydraulic oil of the rodless cavity of the bucket composite cylinder 12-4 to return to the tank 23 through the throttling device in the valve. When the loader bucket oil cylinder retracts, the right position of the third bucket electromagnetic switch valve 11-3 can also make the hydraulic oil of the rodless cavity of the bucket composite cylinder 12-4 quickly flow to the rod cavity of the bucket composite cylinder 12-4. When the bucket does not act, the electromagnetic switch valves in the bucket distributed valve group 11 are all in the closed state.

[0059] When in the power mode, the electric drive and the hydraulic drive respond to work at the same time, realizing the electro-hydraulic composite drive.

[0060] When in the energy recovery mode, the fourth motor 12-2 is in the generator working condition, converts mechanical energy into electric energy for energy recovery, and if the SOC of the power battery (not shown in the figure) in the system exceeds 95%, the energy recovery is stopped.

[0061] Example C

[0062] When the boom cylinder of the loader is extended, the driver controls the handle 19, the vehicle controller 18 receives the handle signal, judges the current driving mode, when in the economic mode, that is, the demand is economy, the vehicle controller 18 sends a control signal to the fifth motor controller 17-1, the fifth motor controller 17-1 controls the fifth motor 17-2 to rotate, and through the second coupling 17-3 to reduce the speed, drives the roller screw rod to rotate and convert into linear action. At this time, if the pure electric drive thrust is insufficient, the hydraulic drive intervenes to assist the output, the third motor controller 13 controls the third motor 14 to drive the second variable pump 15 to rotate, the third motor 14 changes the speed in combination with the second variable pump 15 to change the displacement, and the flow is supplied to the P port of the first boom electromagnetic switch valve 16-1 and the second boom electromagnetic switch valve 16-2 according to the demand. At this time, the second boom electromagnetic switch valve 16-2 is in the right position and works, controls the flow through the throttle device in the valve and delivers the flow to the rodless cavity of the left boom composite cylinder 17-4 and the right boom composite cylinder 17-5, and at the same time, the first boom electromagnetic switch valve 16-1, the third boom electromagnetic switch valve 16-3, the fifth boom electromagnetic switch valve 16-5 are in the closed state, and the fourth boom electromagnetic switch valve 16-4 is in the left position and works, controls the hydraulic oil of the left boom composite cylinder 17-4 and the right boom composite cylinder 17-5 to return to the tank 23 through the throttle device in the valve.

[0063] When in the power mode, that is, the demand is power, the electric drive and the hydraulic drive work at the same time.

[0064] When the loader boom cylinder retracts, the driver controls the operating handle 19, the vehicle controller 18 receives the handle signal, judges the current driving mode, when in the economy mode, the vehicle controller 18 sends a control signal to the fifth motor controller 17-1, the fifth motor controller 17-1 controls the fifth motor 17-2 to rotate, and through the second coupling 17-3 to reduce the speed, drives the roller screw to rotate and convert into linear action. At this time, if the pure electric drive thrust is insufficient, the hydraulic drive intervenes to assist the output, the third motor controller 13 controls the third motor 14 to drive the second variable pump 15 to rotate, the third motor 14 changes the speed in combination with the second variable pump 15 to change the displacement, and supplies the flow to the P port of the first boom electromagnetic switch valve 16-1 and the second boom electromagnetic switch valve 16-2 according to the demand. At this time, the first boom electromagnetic switch valve 16-1 is in the left position and works, controls the flow through the throttling device in the valve and delivers the flow to the rod cavity of the left boom composite cylinder 17-4 and the right boom composite cylinder 17-5, and at the same time, the second boom electromagnetic switch valve 16-2, the third boom electromagnetic switch valve 16-3 and the fourth boom electromagnetic switch valve 16-4 are in the closed state, and the fifth boom electromagnetic switch valve 16-5 is in the right position and works, controls the hydraulic oil of the rodless cavity of the left boom composite cylinder 17-4 and the right boom composite cylinder 17-5 to return to the tank 23 through the throttling device in the valve. When the loader boom cylinder retracts, the hydraulic oil of the rodless cavity of the left boom composite cylinder 17-4 and the right boom composite cylinder 17-5 can also flow to the rod cavity through the right position of the third boom electromagnetic switch valve 16-3. When the boom does not act, the electromagnetic switch valves in the boom distributed valve group 16 are in the closed state. When in the power mode, the electric drive and the hydraulic drive work at the same time.

[0065] When in the energy recovery mode, the vehicle controller 18 judges the current energy recovery mode, when in the stable energy recovery mode, the pure electric energy recovery is used, the fifth motor 17-2 is in the generator working condition, mechanical energy is converted into electric energy for energy recovery, when the battery SOC exceeds 95%, the electric energy recovery is stopped, the hydraulic energy recovery intervenes, at this time, the proportional electromagnetic switch valve 21 is opened, the hydraulic accumulator 22 recovers the hydraulic pressure, when the accumulator SOC exceeds 95%, the energy recovery is stopped. When in the strong energy recovery mode, the electro-hydraulic composite energy recovery is used, until the battery SOC or the hydraulic accumulator SOC exceeds 95%, the energy recovery is stopped.

[0066] The system controls the first motor 2 to rotate through the vehicle controller 18, drives the first fixed displacement pump 3 to supply flow to the steering cylinder, and realizes steering. The vehicle controller 18 controls the second motor 9 to rotate and the first variable displacement pump 10 to supply flow to the bucket cylinder, realizes independent control of the inlet and outlet of the bucket through the bucket distribution valve group 11, and simultaneously controls the fourth motor 12-2 to rotate, realizes electro-hydraulic composite driving of the bucket, and controls the third motor 14 to rotate and the second variable displacement pump 15 to supply flow to the boom cylinder, realizes independent control of the inlet and outlet of the boom through the boom distribution valve group 16, and simultaneously controls the fifth motor 17-2 to rotate, realizes electro-hydraulic composite driving of the boom.

[0067] The present application decouples the steering device, the boom device and the bucket device of the conventional loader, realizes independent and efficient driving of each part, effectively reduces bypass throttling loss relative to the conventional loader system, greatly improves the overall efficiency, makes each actuator not be disturbed, reduces the difficulty of system control, shortens the response time, and enhances the control performance. The boom and the bucket are driven by electro-hydraulic composite cylinders, effectively combine the advantages of high efficiency, fast response, good smooth energy recovery performance of electric drive and good impact resistance, large thrust, high power density, good instantaneous energy recovery performance of hydraulic drive, and improve the performance requirements of the overall economy and power of the vehicle.

[0068] The application of the electro-hydraulic composite cylinder in the electric loader distributed hydraulic system and the control strategy thereof provided by the present application are particularly suitable for loaders with large load fluctuation and complex and harsh working conditions, can enhance the controllability of the loader working device, and greatly improve the energy utilization rate of the overall machine.

[0069] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A distributed hydraulic system for an electric loader using an electro-hydraulic composite cylinder, comprising a body of the distributed hydraulic system for an electric loader, characterized in that: The ontology includes: Steering drive subsystem, a first pumping device, a second pumping device, a bucket distributed valve group (11), a bucket electro-hydraulic composite cylinder (12), a boom distributed valve group (16), a boom electro-hydraulic composite cylinder (17), a vehicle controller (18), a control handle (19), a steering wheel (20), a proportional electromagnetic switch valve (21), and a hydraulic accumulator (22); The bucket distributed valve group (11) is composed of a first bucket electromagnetic switch valve (11-1), a second bucket electromagnetic switch valve (11-2), a third bucket electromagnetic switch valve (11-3), a fourth bucket electromagnetic switch valve (11-4) and a fifth bucket electromagnetic switch valve (11-5); and is connected to the bucket electro-hydraulic composite cylinder (12) and the first pumping device to form a bucket subsystem, and the first pumping device is connected to the oil tank; The boom distributed valve group (16) is composed of a first boom electromagnetic switch valve (16-1), a second boom electromagnetic switch valve (16-2), a third boom electromagnetic switch valve (16-3), a fourth boom electromagnetic switch valve (16-4), and a fifth boom electromagnetic switch valve (16-5); and is connected to the boom electro-hydraulic composite cylinder (17) and a second pumping device to form a boom subsystem, and the second pumping device is connected to the oil tank; The boom electro-hydraulic composite cylinder (17) is connected to the hydraulic accumulator (22) via a proportional electromagnetic switch valve (21); The body is connected and controlled by the vehicle controller (18) using a CAN network low-voltage wiring harness; wherein the vehicle controller (18) is configured as follows: capable of controlling a steering drive subsystem based on a steering wheel (20) signal; The driving modes of the bucket subsystem and the boom subsystem can also be switched based on the signal of the control handle (19), including electric drive, hydraulic drive or electro-hydraulic composite drive.

2. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 1, characterized in that: The steering drive subsystem comprises a first motor controller (1), a first motor (2), a first metering pump (3), an overflow valve (4), a one-way valve (5), a left steering cylinder (6), and a right steering cylinder (7); The first pumping device comprises a second motor controller (8), a second motor (9) and a first variable displacement pump (10); The second pumping device comprises a third motor controller (13), a third motor (14), and a second variable displacement pump (15); The first motor (2) is mechanically connected to the first fixed displacement pump (3); the second motor (9) is mechanically connected to the first variable displacement pump (10); and the third motor (14) is mechanically connected to the second variable displacement pump (15). The bucket electro-hydraulic composite cylinder (12) comprises a fourth motor controller (12-1), a fourth motor (12-2), a first coupler (12-3) and a bucket composite cylinder (12-4); The boom electro-hydraulic composite cylinder (17) comprises a fifth motor controller (17-1), a fifth motor (17-2), a second coupler (17-3), a left boom composite cylinder (17-4) and a right boom composite cylinder (17-5); The fourth motor (12-2) is mechanically connected to the first coupler (12-3); the first coupler (12-3) is mechanically connected to the bucket composite cylinder (12-4); the fifth motor (17-2) is mechanically connected to the second coupler (17-3); the second coupler (17-3) is mechanically connected to the left boom composite cylinder (17-4) and the right boom composite cylinder (17-5), respectively; The first metering pump (3) is connected to the hydraulic pipeline of the overflow valve (4); the first metering pump (3) is connected to the hydraulic pipeline of the one-way valve (5); the first metering pump (3) is connected to the hydraulic pipeline of the left steering cylinder (6) and the right steering cylinder (7); the first variable pump (10) is connected to the hydraulic pipeline of the bucket distributed valve group (11); the bucket distributed valve group (11) is connected to the hydraulic pipeline of the bucket composite cylinder (12-4); the second variable pump (15) is connected to the hydraulic pipeline of the boom distributed valve group (16); the boom distributed valve group (16) is respectively connected to the hydraulic pipelines of the left boom composite cylinder (17-4) and the right boom composite cylinder (17-5); the rodless chambers of the left boom composite cylinder (17-4) and the right boom composite cylinder (17-5) are respectively connected to the hydraulic pipelines of the proportional electromagnetic switch valve (21); the proportional electromagnetic switch valve (21) is connected to the hydraulic pipeline of the hydraulic accumulator (22); The first motor controller (1) is connected to the high-voltage wire harness of the first motor (2); the second motor controller (8) is connected to the high-voltage wire harness of the second motor (9); the third motor controller (13) is connected to the high-voltage wire harness of the third motor (14); the fourth motor controller (12-1) is connected to the high-voltage wire harness of the fourth motor (12-2); and the fifth motor controller (17-1) is connected to the high-voltage wire harness of the fifth motor (17-2).

3. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: In the bucket distributed valve group (11), the first bucket electromagnetic switch valve (11-1) and the second bucket electromagnetic switch valve (11-2) are respectively connected to the oil outlet of the first variable pump (10) and are also connected to the bucket composite cylinder (12-4); the fourth bucket electromagnetic switch valve (11-4) and the fifth bucket electromagnetic switch valve (11-5) are respectively connected to the bucket composite cylinder (12-4) and are also connected to the oil tank; the third bucket electromagnetic switch valve (11-3) is used to connect the rod chamber and the rodless chamber of the bucket composite cylinder (12-4).

4. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: In the boom distributed valve group (16), the first boom electromagnetic switch valve (16-1) is respectively connected to the oil outlet of the second variable pump (15) and the rod chambers of the left boom compound cylinder (17-4) and the right boom compound cylinder (17-5); the second boom electromagnetic switch valve (16-2) is respectively connected to the oil outlet of the second variable pump (15) and the rodless chambers of the left boom compound cylinder (17-4) and the right boom compound cylinder (17-5); the fourth boom electromagnetic switch valve (16-4) and the fifth boom electromagnetic switch valve (16-5) are respectively connected to the left boom compound cylinder (17-4), the right boom compound cylinder (17-5) and the oil tank to allow the oil to flow back to the oil tank; the third boom electromagnetic switch valve (16-3) is used to connect the rod chamber and the rodless chamber of the left boom compound cylinder (17-4) and the right boom compound cylinder (17-5).

5. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: In the electric drive part of the bucket electro-hydraulic composite cylinder (12), it is configured to be driven by the rotation of the fourth motor (12-2) and decelerated through the first coupler (12-3), thereby being able to convert the rotation into linear motion through the roller screw.

6. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: In the electric drive part of the boom electro-hydraulic composite cylinder (17), it is configured to be driven by the rotation of the fifth motor (17-2) and decelerated through the second coupler (17-3), thereby being able to convert the rotation into linear motion through the roller screw.

7. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: The main body also has an energy recovery mode. When energy recovery is performed, the vehicle controller (18) is configured to dynamically allocate electric energy recovery and hydraulic energy recovery paths according to the battery SOC and hydraulic accumulator SOC values.

8. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 7, characterized in that: During energy recovery, the bucket electro-hydraulic composite cylinder (12) can convert mechanical energy into electrical energy through the fourth motor (12-2) in a generator state to perform energy recovery; The boom electro-hydraulic composite cylinder (17) can convert energy into electrical energy for energy recovery through the fifth motor (17-2) in a generator operating state, and can also recover hydraulic energy through the hydraulic accumulator (22).

9. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 2, characterized in that: The vehicle controller (18) receives a signal from the control handle (19) to determine the driving mode. When the driving mode is economical, the bucket electro-hydraulic composite cylinder (12) and the boom electro-hydraulic composite cylinder (17) are driven by separate electric drives; When the driving mode is dynamic, the bucket electro-hydraulic composite cylinder (12) and the boom electro-hydraulic composite cylinder (17) are simultaneously powered by the electro-hydraulic composite drive.

10. The distributed hydraulic system for electric loaders using an electro-hydraulic composite cylinder according to claim 9, characterized in that: When the electric drive exceeds the rated torque of the motor, the hydraulic drive intervenes to provide assistance and power.

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