Pump-controlled hydraulic system and control method

Abstract

The invention discloses a pump-controlled hydraulic system and a control method. The pump-controlled hydraulic system is provided with a driving motor, a bidirectional hydraulic pump, an oil tank, a filter, a hydraulic execution element and an oil way valve group, an oil path A and an oil path B are respectively connected from two ends of the bidirectional hydraulic pump to two cavities of the hydraulic execution element; a system overflow valve I, a hydraulic control one-way valve I, an electromagnetic directional valve and an oil return overflow valve are arranged on the rod cavity oil path A; a second system overflow valve and a second hydraulic control one-way valve are arranged on the rodless cavity oil way B; meanwhile, an oil path C is connected between the oil path at the oil inlet front end of the first hydraulic control one-way valve and the control end of the second hydraulic control one-way valve; and an oil path D is connected between the oil path at the oil inlet front end of the hydraulic control one-way valve II and the control end of the hydraulic control one-way valve I. According to the structure, the two-way pump can be used for controlling the flow direction of hydraulic oil in the two cavities of the execution element, so that the system pressure loss is reduced, and the back pressure of the rodless cavity is reduced.

Description

Technical Field

[0001] The invention relates to the field of hydraulic system control, and in particular to a structure and a control method of an energy-saving pump-controlled hydraulic control circuit. Background Art

[0002] Hydraulic transmission technology has penetrated almost all modern engineering construction fields and is the most important power transmission method in automatic control and engineering machinery actuators. The existing hydraulic system has two basic methods for speed control of actuators. The first is the control method of hydrostatic transmission, which adjusts the displacement of the variable pump by changing the speed of the power source and the load pressure to achieve the purpose of adjusting the system flow; the second is the mode of quantitative pump plus throttle valve, which adjusts the system flow by adjusting the size of the throttle valve port. In the first method, there is no throttling loss because there is no throttle valve, and the energy efficiency is high, but hydrostatic transmission requires the use of expensive variable pumps and load-sensitive valves, and one working device corresponds to a set of variable systems, and the quality requirements of hydraulic oil are very high, so the cost of hydrostatic transmission is high and it is only used in high-end hydraulic systems. The cost of the second method pump and valve is not high, and it is not sensitive to the quality of hydraulic oil, so it has been widely used, but it will cause large throttling loss and overflow loss when adjusting the flow. At the same time, both existing hydraulic systems will cause unnecessary pressure loss along the way due to the long hydraulic circuit pipeline. Moreover, most of the current hydraulic systems use centralized hydraulic systems. The power oil from the hydraulic pump is used for load balancing and flow distribution of multiple actuators through an integral multi-way valve. The loads of the centralized hydraulic system are coupled with each other, resulting in low system operation energy efficiency. The centralized pressure oil drive pipeline is long, which will also cause unnecessary pressure loss along the way. It is reported that the efficiency of the hydraulic system of construction machinery is about 30%. A large amount of hydraulic energy is lost and converted into heat energy, causing the system to heat up, and the system efficiency is low.

[0003] Therefore, in a control system based mainly on valve control, energy loss is difficult to avoid. Summary of the invention

[0004] In order to reduce unnecessary energy loss of the hydraulic system and give full play to the power advantage of the hydraulic system, the present invention proposes an energy-saving pump-controlled hydraulic system and control method based on the characteristics of the three-electric technology. Its main features are: a hydraulic working device uses a separate hydraulic system, which is composed of a separate motor, a hydraulic pump, a hydraulic actuator and related auxiliary hydraulic components that are integrated together. The pump controls the flow direction and flow rate of the entire hydraulic circuit and converts mechanical energy into hydraulic energy; the motor adopts speed control to adjust the flow of the hydraulic system at different speeds according to the output of the operator; the actuator is responsible for providing power to the outside world; and the related auxiliary hydraulic components protect the realization of the system function. This system is used in conditions where the hydraulic cylinder works horizontally and the inertia of the accessories driven by the hydraulic motor is very small, which can reduce the system backup power and improve work efficiency.

[0005] The technical solution of the present invention is:

[0006] A pump-controlled hydraulic system includes a drive motor, a hydraulic pump, an oil tank, a filter, a hydraulic actuator and an oil circuit valve group;

[0007] The present invention adopts a bidirectional hydraulic pump, both ends of which are connected to the oil circuit A to the rodless chamber of the hydraulic actuator and to the oil circuit B to the rod chamber;

[0008] A system overflow valve 1, a hydraulically controlled one-way valve 1, an electromagnetic reversing valve and an oil return overflow valve are arranged on the oil circuit A;

[0009] A system overflow valve 2 and a hydraulically controlled one-way valve 2 are provided on oil circuit B.

[0010] In the above system, further, an oil circuit C is connected between the oil circuit at the front end of the oil inlet of the hydraulically controlled one-way valve one and the control end of the hydraulically controlled one-way valve two; an oil circuit D is connected between the oil circuit at the front end of the oil inlet of the hydraulically controlled one-way valve two and the control end of the hydraulically controlled one-way valve one.

[0011] In the above system, further, the hydraulically controlled one-way valve 1 and the hydraulically controlled one-way valve 2 are both normally closed valves, which are connected toward the oil chamber in their respective oil circuits.

[0012] In the above system, further, the system overflow valve 1 is connected between the oil inlet end of the hydraulically controlled one-way valve 1 and the bidirectional hydraulic pump; the system overflow valve 2 is connected between the oil inlet end of the hydraulically controlled one-way valve 2 and the bidirectional hydraulic pump.

[0013] In the above system, further, the solenoid reversing valve and the return oil overflow valve are connected in series, one end of the solenoid reversing valve is connected to the oil circuit between the system overflow valve and the two-way hydraulic pump, and the other end is connected to the return oil overflow valve, and the overflow end of the return oil overflow valve is connected to the oil tank; the solenoid reversing valve is a normally closed valve, which is turned on when powered on.

[0014] In the above system, further, the overflow pressure of the return oil overflow valve is smaller than the overflow pressure of the system overflow valve 1 and the system overflow valve 2.

[0015] In the above system, further, the electromagnetic reversing valve and the oil return relief valve are equivalently replaced by a multi-stage relief valve.

[0016] In the above system, further, the oil tank supply pipeline is divided into two routes after passing through the filter and respectively connected to the two ends of the bidirectional hydraulic pump; ordinary one-way valves are respectively arranged on the two pipelines.

[0017] The present invention also provides a control method for the above system:

[0018] The handle opening corresponding to the driving motor speed and the action speed of the hydraulic actuator are calibrated in advance, and the motor torque is adaptive;

[0019] 1) When the handle operation command requires the piston rod of the hydraulic actuator to retreat, the speed of the drive motor is controlled according to the handle opening, and the drive motor drives the bidirectional hydraulic pump to rotate and controls the oil supply direction from the rodless chamber to the rod chamber;

[0020] Initially, oil is pumped from the oil tank, and after passing through the bidirectional hydraulic pump, the hydraulically controlled one-way valve 2 on the rod chamber oil circuit B is opened under the action of the positive hydraulic pressure;

[0021] At the same time, under the action of the oil circuit connected between the oil outlet end of the pump and the control end of the hydraulically controlled one-way valve 1 on the rodless chamber oil circuit A, the hydraulically controlled one-way valve 1 on the rodless chamber oil circuit A is also opened under the action of hydraulic pressure, and the hydraulic oil in the rodless chamber flows through the oil circuit A, the two-way hydraulic pump and the oil circuit B into the rod chamber;

[0022] At the same time, the electromagnetic reversing valve is energized and turned on, and part of the oil in oil circuit A returns to the oil tank through the electromagnetic reversing valve and the return oil overflow valve according to the set return oil overflow pressure;

[0023] After this, the oil in the tank does not need to be refilled;

[0024] 2) When the handle operation command requires the piston rod of the hydraulic actuator to extend, the speed of the drive motor is controlled according to the handle opening, and the drive motor drives the bidirectional hydraulic pump to rotate and controls the oil supply direction from the rod chamber to the rodless chamber;

[0025] This process does not require the solenoid reversing valve to be powered on;

[0026] Initially, oil is pumped from the oil tank, and after passing through the bidirectional hydraulic pump, the hydraulically controlled one-way valve on the rodless chamber oil circuit A is opened under the negative hydraulic pressure.

[0027] At the same time, under the action of the oil circuit connected between the oil outlet end of the pump and the control end of the second hydraulically controlled one-way valve on the oil circuit B of the rod chamber, the second hydraulically controlled one-way valve on the oil circuit B of the rod chamber is also opened under the action of hydraulic pressure, and the hydraulic oil in the rod chamber flows through the oil circuit B, the two-way hydraulic pump and the oil circuit A into the rodless chamber;

[0028] After this, the oil in the tank is used only for topping-up.

[0029] The present invention can be applied to distributed hydraulic control systems and has strong independent controllability over a single working device. In the circuit, pump control is used to eliminate valve throttling losses, unnecessary overflow losses and mid-position oil return losses, and to minimize pressure losses along the pipeline, thereby saving energy and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the pump-controlled hydraulic system provided by the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the embodiments. Those skilled in the art should know that the following embodiments are not the only limitations on the technical solutions of the present invention, and any equivalent changes or modifications made within the spirit of the technical solutions of the present invention should be deemed to fall within the protection scope of the present invention.

[0032] The pump-controlled hydraulic system refers to a solution in which a working device is controlled by a pump through an independent hydraulic circuit consisting of a set of motors, hydraulic pumps, working valve groups and actuators. The pump-controlled hydraulic solution has strong independent controllability. The selection of motors, pumps and valves only needs to be configured according to the working requirements of the controlled device, without considering the requirements of other working devices; on the other hand, the pump-controlled hydraulic system can be arranged close to the working device, saving the length of the oil circuit and the loss along the oil circuit.

[0033] The present invention provides a pump-controlled hydraulic system which can be applied to a distributed hydraulic control system, and aims to eliminate the throttling loss, unnecessary overflow loss and mid-position oil return loss of the valve in an independent control loop, and to reduce the pressure loss along the pipeline as much as possible, thereby saving energy and increasing efficiency.

[0034] As shown in FIG. 1 , the components used in the hydraulic system of the present invention include a driving motor 1, a bidirectional hydraulic pump 2, an oil tank 3, a filter 4, a hydraulic actuator 5, and an oil circuit valve group. The above components constitute a control circuit for the hydraulic actuator 5 to drive the hydraulic actuator 5 to operate. The hydraulic actuator 5 in the structure of the present invention can be applied as a hydraulic cylinder or a hydraulic motor with a small inertia. The hydraulic cylinder is taken as an example for description below.

[0035] The feature of the present invention is pump control, which drives the flow of hydraulic oil through a pump to control the flow direction and flow rate of the hydraulic oil. Therefore, the present invention adopts a bidirectional hydraulic pump 2, and utilizes the bidirectional hydraulic pump 2 and a hydraulic actuator 5 to form a closed-loop hydraulic circuit. The two chambers of the hydraulic actuator 5 are connected to the two ends of the bidirectional hydraulic pump, and the oil supply can be switched in the circuit through the hydraulic pump.

[0036] Because a bidirectional hydraulic pump 2 is used, the oil in the oil tank 3 is filtered by the filter 4 and then supplied to the outside in two ways, which are respectively connected to the two ends of the bidirectional hydraulic pump 2, and are used to supply oil to the bidirectional hydraulic pump 2 from two directions, so that the hydraulic pump can pump oil in both forward and reverse rotations. Furthermore, a common check valve 1 6 and a common check valve 2 7 are respectively arranged on the two oil supply lines of the oil tank 3, and the common check valve 1 6 and the common check valve 2 7 have the function of one-way conduction and preventing backflow, and which one-way check valve is opened is determined by the driving direction of the hydraulic pump.

[0037] Taking the hydraulic cylinder as an example, the hydraulic actuator 5 has oil circuit A connected to the rodless chamber of the hydraulic actuator 5 and oil circuit B connected to the rod chamber of the hydraulic actuator 5 from both ends of the bidirectional hydraulic pump 2. In the hydraulic system structure, the oil circuit valve group can generally be used to control the pressure, flow rate and flow direction of the oil circuit, and the selection and layout of the valve components are the key to the realization of its functions. Therefore, a rodless chamber oil circuit valve group is provided on the oil circuit A leading to the rodless chamber of the hydraulic actuator 5, and a rod chamber oil circuit valve group is provided on the oil circuit B leading to the rod chamber of the hydraulic actuator 5. In the present invention, the rodless chamber valve group is provided with a system overflow valve 1 8, a hydraulically controlled one-way valve 1 9, an electromagnetic reversing valve 10 and an oil return overflow valve 11, and the rod chamber valve group is only provided with a system overflow valve 2 12 and a hydraulically controlled one-way valve 2 13.

[0038] On the oil circuit A from the bidirectional hydraulic pump 2 to the rodless chamber, the hydraulically controlled one-way valve 9 is a normally closed valve, which is conductive in the oil inlet direction of the rodless chamber, and the oil outlet of the hydraulically controlled one-way valve 9 is connected to the oil port of the rodless chamber; the system relief valve 18 is connected between the oil inlet end of the hydraulically controlled one-way valve 9 and the bidirectional hydraulic pump 2; the electromagnetic reversing valve 10 and the return oil relief valve 11 are connected in series, the electromagnetic reversing valve 10 is connected between the access point of the system relief valve 8 and the bidirectional hydraulic pump 2, and the return oil relief valve 11 returns oil to the oil tank. The purpose of such setting is to set a hydraulically controlled one-way valve 9 in the oil circuit so that the pressure of the locking working device does not react on the pump when the system is not working, and the hydraulically controlled one-way valve can be opened when the system is working to ensure the normal operation of the system; a system overflow valve 8 is set below the oil inlet of the hydraulically controlled one-way valve 9 to maintain the system pressure from being overloaded and to avoid damage to system components including pumps and motors; in particular, the electromagnetic reversing valve 10 and the return oil overflow valve 11 are set between the system overflow valve 8 and the two-way hydraulic pump 2, which is the focus of the present invention. The purpose of setting these two parts is to further reduce the oil circuit pressure by low-pressure overflow, because when the rodless chamber transports oil in the direction of the pump, the volume change of the rod chamber when the piston moves is less than the volume change of the rodless chamber, so there will be excess hydraulic oil between the rodless chamber and the pump that needs to overflow, and the return oil overflow valve 11 can reduce this return oil pressure, improve the working efficiency of the system, and also reduce the back oil pressure of the rodless chamber. The overflow pressure of the return oil overflow valve 11 is set lower than the system pressure, but not too low, preferably 0.05 times the system pressure. The electromagnetic reversing valve 10 is a normally closed valve, which is powered on. This design can save a lot of energy consumption of the drive motor when the rodless chamber is depressurized.

[0039] A hydraulically controlled one-way valve 13 is provided on the oil circuit B from the bidirectional hydraulic pump 2 to the rod chamber. Similarly, the hydraulically controlled one-way valve 13 is also a normally closed valve, which is conductive in the oil inlet direction of the rod chamber. The purpose of the setting is to lock the pressure of the working device so that it does not react on the pump when the system is not working. When the system is working, the hydraulically controlled one-way valve can be opened to ensure the normal operation of the system. The system overflow valve 12 is provided below the oil inlet of the hydraulically controlled one-way valve 13 and between the pump, in order to maintain the system pressure from being overloaded and to avoid damage to system components including the pump and the motor. However, low-pressure oil leakage is not required on the oil circuit B from the bidirectional hydraulic pump 2 to the rod chamber, so there is no need to arrange a low-pressure overflow valve.

[0040] Furthermore, the present invention also connects an oil circuit C between the oil circuit at the front end of the oil inlet of the hydraulically controlled one-way valve 19 and the control end of the hydraulically controlled one-way valve 2 13 in the rodless chamber oil circuit, and connects an oil circuit D between the oil circuit at the front end of the oil inlet of the hydraulically controlled one-way valve 2 13 and the control end of the hydraulically controlled one-way valve 19.

[0041] The function of the oil circuit C is that when the bidirectional hydraulic pump 2 supplies oil to the hydraulically controlled one-way valve 19, the pressure oil can transmit the pressure to the control end of the hydraulically controlled one-way valve 13 through the oil circuit C, and use the pressure to open the hydraulically controlled one-way valve 13. This working condition is used when the piston rod of the hydraulic actuator 5 needs to extend outward. On the one hand, the bidirectional hydraulic pump 2 supplies oil to the rodless chamber, and at the same time, the hydraulically controlled one-way valve 13 is opened through the oil circuit C, so that the oil circuit of the rod chamber is also conducted, and then the oil in the rod chamber is leaked out to supply the rodless chamber, realizing the circulation of the oil in the rod chamber to the rodless chamber, so that there is no need to pump oil from the oil tank later, and the oil in the oil tank is only used for replenishing oil.

[0042] Similarly, the function of the oil circuit D is that when the bidirectional hydraulic pump 2 supplies oil to the hydraulic control check valve 13, the pressure oil can be transmitted to the control end of the hydraulic control check valve 19 through the oil circuit D, and the hydraulic control check valve 19 is opened by the pressure. This working condition is used when the piston rod of the hydraulic actuator 5 needs to retreat. On the one hand, the bidirectional hydraulic pump 2 supplies oil to the rod chamber, and at the same time, the hydraulic control check valve 19 is opened through the oil circuit D, so that the oil circuit of the rodless chamber is also conducted, and then the oil in the rodless chamber flows back to the rod chamber, realizing the circulation of the oil in the rodless chamber to the rod chamber, so that there is no need to pump oil from the oil tank later, and the oil in the oil tank is only used for replenishing oil.

[0043] In the hydraulic circuit structure of the present invention, whether it is a rod chamber or a rodless chamber, the conduction of the oil circuit is completely achieved by opening the hydraulically controlled one-way valve through the hydraulic pressure; an electromagnetic reversing valve is specially arranged on the oil circuit at one end of the rodless chamber, which is powered on to reduce pressure and discharge, reduce system pressure, and reduce the back pressure of the rodless chamber; the bidirectional hydraulic pump 2 is driven by a drive motor 1, and the motor speed control is pre-calibrated by the working device action speed requirement corresponding to the handle opening. The bidirectional hydraulic pump 2 has a bidirectional driving effect, which can make the hydraulic oil flow from the rodless chamber of the hydraulic actuator 5 to the rod chamber, and also flow from the rod chamber to the rodless chamber. This structure can make the hydraulic oil flow or remain stationary alternately between the two chambers, avoiding frequent entry and exit of the single-chamber oil circuit in the oil tank and energy loss.

[0044] The electromagnetic reversing valve 10 and the oil return relief valve 11 can also be replaced by a multi-stage relief valve to achieve back pressure oil unloading when the oil returns to the rodless chamber.

[0045] The present invention further applies the above structure to provide a control method, the process of which is:

[0046] The handle opening corresponding to the motor speed and the action speed of the hydraulic actuator are calibrated in advance, and the motor torque is adaptive.

[0047] (1) When the handle operation command requires the piston rod of the hydraulic actuator 5 to retract (when the hydraulic oil needs to flow from the rodless chamber of the hydraulic actuator 5 to the rod chamber), the motor speed is equal to the speed corresponding to the handle opening, the torque is adaptive, the drive motor 1 drives the bidirectional hydraulic pump 2 to rotate and controls the oil supply direction of the bidirectional hydraulic pump 2 from the rodless chamber to the rod chamber; at the same time, the electromagnetic reversing valve 10 is energized to be in a conducting state;

[0048] Initially, under the driving action of the two-way hydraulic pump 2, the ordinary one-way valve 6 is opened, and oil is first pumped from the oil tank. The pressure at the oil outlet end of the two-way hydraulic pump 2 increases (the right end in the figure). After the oil passes through the two-way hydraulic pump 2, the hydraulic control one-way valve 13 of the rod chamber oil circuit B is opened under the positive hydraulic action. At the same time, under the action of the oil circuit D, the hydraulic control one-way valve 9 below the rodless chamber oil circuit is also opened under the pressure of the pump. The hydraulic oil in the rodless chamber can flow back to the two-way hydraulic pump 2 through the hydraulic control one-way valve 9, and then the hydraulic oil flows through the hydraulic control one-way valve 13 to enter the rod chamber of the hydraulic cylinder;

[0049] At this time, due to the low-pressure leakage effect, part of the hydraulic oil will flow through the electromagnetic reversing valve 10 and the return oil relief valve 11 and return to the oil tank;

[0050] After the oil starts to flow in the direction of the rodless chamber - pump - rod chamber, the oil in the oil tank does not need to be replenished.

[0051] (2) When the handle operation command requires the piston rod of the hydraulic actuator 5 to extend (when the hydraulic oil needs to flow from the rod chamber of the hydraulic actuator 5 to the rodless chamber), the driving motor speed is equal to the speed corresponding to the handle opening, the torque is self-adaptive, and the driving motor 1 drives the bidirectional hydraulic pump 2 to rotate and controls the oil supply direction of the bidirectional hydraulic pump 2 from the rod chamber to the rodless chamber; at this time, the electromagnetic reversing valve 10 is not powered on;

[0052] Initially, under the driving action of the two-way hydraulic pump 2, the ordinary one-way valve 27 is opened, and oil is first pumped from the oil tank. The pressure at the oil outlet end of the two-way hydraulic pump 2 increases (the left end in the figure). After the oil passes through the two-way hydraulic pump 2, the hydraulic control one-way valve 19 of the rodless chamber oil circuit A is opened under the pressure provided by the pump. At the same time, under the action of the oil circuit C, the hydraulic control one-way valve 213 below the rod chamber oil circuit is also opened under the pressure of the pump, and the hydraulic oil in the rod chamber can flow back to the two-way hydraulic pump 2 through the hydraulic control one-way valve 213, and then the hydraulic oil flows through the hydraulic control one-way valve 19 into the rodless chamber of the hydraulic cylinder. The pressure in the rodless chamber increases, pushing the piston to the right.

[0053] After the oil starts to flow in the direction of the rod chamber-pump-rodless chamber, the oil in the oil tank is only used for replenishment.

[0054] The above description is only a specific embodiment of the present application, so that those skilled in the art can understand or implement the present application. However, various equivalent modifications and changes to these embodiments will be obvious to those skilled in the art, and the present application will not be limited to these embodiments without departing from the spirit or scope of the present application, but will comply with the scope consistent with the claims of the present application.

Claims

1. A pump-controlled hydraulic system, comprising a drive motor (1), a bidirectional hydraulic pump (2), an oil tank (3), a filter (4), a hydraulic actuator (5) and an oil circuit valve group; characterized in that: An oil circuit A is connected from both ends of a bidirectional hydraulic pump (2) to a rodless chamber of a hydraulic actuator (5), and an oil circuit B is connected to a rod chamber; The oil circuit A is provided with a system overflow valve (8), a hydraulically controlled one-way valve (9), an electromagnetic reversing valve (10) and an oil return overflow valve (11); A system overflow valve 2 (12) and a hydraulically controlled check valve 2 (13) are provided on the oil circuit B.

2. The pump-controlled hydraulic system according to claim 1, characterized in that: An oil circuit C is connected between the oil circuit at the oil inlet front end of the hydraulically controlled one-way valve 1 (9) and the control end of the hydraulically controlled one-way valve 2 (13); An oil circuit D is connected between the oil circuit at the oil inlet front end of the hydraulically controlled one-way valve 2 (13) and the control end of the hydraulically controlled one-way valve 1 (9).

3. The pump-controlled hydraulic system according to claim 1, characterized in that: The hydraulically controlled one-way valve 1 (9) and the hydraulically controlled one-way valve 2 (13) are both normally closed valves, and are connected toward the oil chamber in their respective oil circuits.

4. The pump-controlled hydraulic system according to claim 1, characterized in that: The system overflow valve 1 (8) is connected between the oil inlet end of the hydraulically controlled one-way valve 1 (9) and the bidirectional hydraulic pump (2); The system overflow valve 2 (12) is connected between the oil inlet end of the hydraulically controlled check valve 2 (13) and the bidirectional hydraulic pump (2).

5. The pump-controlled hydraulic system according to claim 1, characterized in that: The electromagnetic reversing valve (10) and the oil return overflow valve (11) are connected in series, one end of the electromagnetic reversing valve (10) is connected to the oil circuit between the system overflow valve 1 (8) and the bidirectional hydraulic pump (2), and the other end is connected to the oil return overflow valve (11), and the overflow end of the oil return overflow valve (11) is connected to the oil tank; The electromagnetic reversing valve (10) is a normally closed valve and is conductive when powered on.

6. The pump-controlled hydraulic system according to claim 1, characterized in that: The overflow pressure of the oil return overflow valve (11) is smaller than the overflow pressure of the system overflow valve 1 (8) and the system overflow valve 2 (12).

7. The pump-controlled hydraulic system according to claim 1, characterized in that: The electromagnetic reversing valve (10) and the oil return overflow valve (11) are equivalently replaced by a multi-stage overflow valve.

8. The pump-controlled hydraulic system according to claim 1, characterized in that: The oil supply pipeline of the oil tank (3) is divided into two routes after passing through the filter (4) and respectively connected to the two ends of the bidirectional hydraulic pump (2); ordinary one-way valves are respectively arranged on the two pipelines.

9. A method for controlling the pump-controlled hydraulic system according to any one of claims 1 to 8, characterized in that: The handle opening corresponding to the rotation speed of the driving motor (1) and the action speed of the hydraulic actuator are calibrated in advance, and the motor torque is adaptive; 1) When the handle operation command requires the piston rod of the hydraulic actuator (5) to retreat, the rotation speed of the drive motor (1) is controlled according to the handle opening, and the drive motor (1) drives the bidirectional hydraulic pump (2) to rotate and control the oil supply direction from the rodless chamber to the rod chamber; Initially, oil is pumped from the oil tank (3), and after the oil passes through the bidirectional hydraulic pump (2), the hydraulically controlled check valve 2 (13) on the rod chamber oil circuit B is opened under the action of the positive hydraulic pressure; At the same time, under the action of the oil circuit connected between the oil outlet end of the pump and the control end of the hydraulically controlled one-way valve (9) on the rodless chamber oil circuit A, the hydraulically controlled one-way valve (9) on the rodless chamber oil circuit A is also opened under the action of the hydraulic pressure, and the hydraulic oil in the rodless chamber flows through the oil circuit A, the two-way hydraulic pump (2) and the oil circuit B into the rod chamber; At the same time, the electromagnetic reversing valve (10) is energized and turned on, and part of the oil in the oil circuit A returns to the oil tank through the electromagnetic reversing valve (10) and the oil return overflow valve (11) according to the set oil return overflow pressure; After this, the oil in the oil tank (3) does not need to be replenished; 2) When the handle operation command requires the piston rod of the hydraulic actuator (5) to extend, the rotation speed of the drive motor (1) is controlled according to the handle opening, and the drive motor (1) drives the bidirectional hydraulic pump (2) to rotate and control the oil supply direction from the rod chamber to the rodless chamber; This process does not require the electromagnetic reversing valve (10) to be powered on; Initially, oil is pumped from the oil tank (3), and after the oil passes through the bidirectional hydraulic pump (2), the hydraulically controlled one-way valve (9) on the rodless chamber oil circuit A is opened under the negative hydraulic pressure. At the same time, under the action of the oil circuit connected between the oil outlet end of the pump and the control end of the hydraulically controlled one-way valve 2 (13) on the rod chamber oil circuit B, the hydraulically controlled one-way valve 2 (13) on the rod chamber oil circuit B is also opened under the action of the hydraulic pressure, and the hydraulic oil in the rod chamber flows through the oil circuit B, the two-way hydraulic pump (2) and the oil circuit A into the rodless chamber; Thereafter, the oil in the oil tank (3) is only used for replenishment.

Images