A multi-actuator hydraulic pump control system and control method for a parallel valve-controlled circuit

Abstract

The application discloses a kind of parallel valve control loop's multiple actuator hydraulic pump control system and control method.Parallel execution hydraulic pump control module and variable hydraulic pump are connected with hydraulic oil tank, alternating current motor and variable hydraulic pump are electrically connected, parallel execution hydraulic pump control module is mainly formed by a plurality of single-stage execution hydraulic pump control unit parallel, fixed quantity hydraulic pump and variable speed servo motor are connected, two ends of fixed quantity hydraulic pump are connected with hydraulic oil tank and three-position four-way switch reversing valve respectively, three-position four-way switch reversing valve is communicated with actuator, one oil port in three-position four-way proportional reversing valve is communicated with actuator, another oil port is connected with variable pump or hydraulic oil tank.The application compensates the dynamic response performance of pump by adding parallel valve control loop, utilizes pump control feedforward flow, valve control feedback flow, realizes the motion servo control of hydraulic actuator.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic transmission and control, and in particular relates to a multi-actuator hydraulic pump control system and control method with parallel valve control circuit. Background Technology

[0002] Pump control systems are a typical way to achieve high-efficiency operation in the field of hydraulic transmission and control. Compared with the closed pump control systems commonly used in the aerospace field, open pump control systems have a significant advantage in heat dissipation and are more suitable for heavy-duty, high-intensity tasks in the field of hydraulic transmission and control. With the development of motor servo speed regulation technology, variable speed servo motors driving fixed displacement pumps have become an important pump control method. Compared with variable displacement pumps, they are simpler in structure and have good application prospects. In multi-actuator hydraulic pump control systems, each actuator needs to be equipped with a hydraulic pump. Its advantage lies in the high energy efficiency brought by volumetric control. It has been applied in some engineering machinery. However, compared with valve control systems, hydraulic pumps have a large moment of inertia and poor dynamic performance in the flow adjustment process. In some high-dynamic application scenarios that require rapid acceleration and deceleration, the control accuracy is not good.

[0003] The valve control system composed of proportional valves is a traditional hydraulic control system. Modern proportional directional valves can achieve a frequency response of tens or even hundreds of hertz, which is conducive to achieving good control performance. They are especially suitable for high dynamic scenarios such as rapid acceleration and deceleration. However, the throttling loss at the valve orifice will reduce the system's energy efficiency.

[0004] Model-based control methods have been well-established in the motion control of hydraulic actuators. The basic idea is to compensate for the model's dynamic characteristics (i.e., feedforward control) and simultaneously perform feedback control based on measurement errors to ensure closed-loop control accuracy. In summary, the cooperation between pumps and valves to leverage their respective advantages is a highly promising approach for hydraulic actuator control. However, breakthroughs are needed in both loop configuration and control methods. Current technology lacks a multi-actuator hydraulic pump control system and its control method that can compensate for the performance of the pump control system through parallel valve control loops, thereby achieving high-performance motion control of actuators in highly dynamic application scenarios. Summary of the Invention

[0005] To overcome the aforementioned shortcomings, the present invention aims to provide a multi-actuator hydraulic pump control system and control method with parallel valve control loops. Based on the multi-actuator hydraulic pump control system, the present invention achieves performance compensation in high-dynamic application scenarios through parallel valve control loops, especially to compensate for the slow dynamic response speed of the hydraulic pump. Through feedforward feedback composite control, it can compensate for insufficient flow and discharge excess flow for the actuator, ultimately achieving precise motion control.

[0006] The technical solution adopted in this invention is as follows:

[0007] I. A multi-actuator hydraulic pump control system with parallel valve control circuits:

[0008] The system includes a parallel execution hydraulic pump control module, a variable hydraulic pump, an AC motor, and a hydraulic oil tank; both the parallel execution hydraulic pump control module and the variable hydraulic pump are connected to the hydraulic oil tank, and the AC motor and the variable hydraulic pump are electrically connected; the parallel execution hydraulic pump control module is mainly formed by several single-stage execution hydraulic pump control units connected in parallel.

[0009] The single-stage hydraulic pump control unit mainly consists of an actuator, a hydraulic pump control component, and a parallel valve control circuit. The input end of the hydraulic pump control component is connected to the output end of the hydraulic oil tank, and the output end of the hydraulic pump control component is connected to the input end of the actuator. The two ends of the parallel valve control circuit group are respectively connected to the hydraulic oil tank and the actuator. The parallel valve control circuit group is used to control the flow direction of hydraulic oil in the actuator.

[0010] The hydraulic pump control component includes a three-position four-way directional valve, a fixed displacement hydraulic pump, and a variable speed servo motor. The fixed displacement hydraulic pump and the variable speed servo motor are electrically connected. The variable speed servo motor is used to control the speed of the fixed displacement hydraulic pump. The suction port of the fixed displacement hydraulic pump is connected to the outlet port of the hydraulic oil tank. The outlet port of the fixed displacement hydraulic pump is connected to the inlet port P of the three-position four-way directional valve. The outlet port of the three-position four-way directional valve is connected to the hydraulic oil chamber of the actuator.

[0011] The parallel valve control circuit mainly consists of two three-position four-way proportional directional valves. One port of each three-position four-way proportional directional valve is connected to the hydraulic oil chamber of the actuator, and the other port is connected to the output end of the variable pump or the hydraulic oil tank. The three-position four-way proportional directional valve is used to control the flow direction of hydraulic oil between the hydraulic oil tank and the actuator.

[0012] When the hydraulic oil chamber of the actuator is replenished with oil, the oil inlet P of the three-position four-way proportional directional valve is connected to the oil outlet of the hydraulic oil tank through the variable pump. The oil outlet of the three-position four-way proportional directional valve is connected to the hydraulic oil chamber in the actuator that needs to be replenished with oil, so that the hydraulic oil in the hydraulic oil tank flows to the hydraulic oil chamber of the actuator in sequence through the variable pump and the three-position four-way proportional directional valve.

[0013] When hydraulic oil flows out of the hydraulic oil chamber of the actuator, the return port T of the three-position four-way proportional directional valve is connected to the hydraulic oil tank, and the inlet of the three-position four-way proportional directional valve is connected to the hydraulic oil chamber in the actuator that is to be drained, so that the hydraulic oil in the hydraulic oil chamber of the actuator flows back to the hydraulic oil tank through the three-position four-way proportional directional valve.

[0014] The actuator is either a hydraulic cylinder or a hydraulic motor. The number of actuators in the parallel hydraulic pump control module is unlimited, and the number of actuators, hydraulic pump control components and parallel valve control circuits is the same.

[0015] II. A hydraulic flow control method, comprising the following steps:

[0016] Step 1: First, connect the actuator and the fixed displacement hydraulic pump through a three-position four-way directional valve, and control the working state of the three-position four-way directional valve to make the actuator be in the preset motion state.

[0017] Step 2: Then, the speed of the fixed displacement hydraulic pump is controlled in real time by a variable speed servo motor, thereby controlling the flow rate of hydraulic oil from the hydraulic tank to the actuator after passing through the fixed displacement hydraulic pump and the three-position four-way switch directional valve.

[0018] Step 3: Next, according to the preset feedback control quantity, control the working state of the two three-position four-way proportional directional valves, thereby controlling the flow direction of hydraulic oil between the actuator and the hydraulic oil tank. During the process, the speed of the variable hydraulic pump is controlled in real time by the AC motor, thereby controlling the flow rate of hydraulic oil from the hydraulic oil tank to the actuator after passing through the variable hydraulic pump.

[0019] Precise control of the actuator's motion state is achieved by using fixed displacement hydraulic pumps and variable displacement hydraulic pumps to precisely control the flow of hydraulic oil.

[0020] In step 1, the specific operation of using a three-position four-way directional valve to bring the actuator to a preset motion state is as follows:

[0021] If the hydraulic cylinder is in the forward motion state, the three-position four-way switch directional valve is in the left position, and the quantitative hydraulic pump controls the hydraulic oil to flow from the hydraulic oil tank to the left chamber of the hydraulic cylinder, causing the hydraulic rod of the hydraulic cylinder to move to the right.

[0022] If the hydraulic cylinder is in the reverse motion state, the three-position four-way switch directional valve is in the right position, and the quantitative hydraulic pump controls the hydraulic oil to flow from the hydraulic oil tank to the right chamber of the hydraulic cylinder, so that the hydraulic rod of the hydraulic cylinder moves to the left.

[0023] If the hydraulic motor is in the forward motion state, the three-position four-way switch directional valve is in the left position, and the fixed-displacement hydraulic pump controls the hydraulic oil to flow from the hydraulic oil tank to the left chamber of the hydraulic motor.

[0024] In step 3, the specific method for controlling the hydraulic oil flow direction using a three-position four-way proportional directional valve is as follows:

[0025] When the left chamber of the hydraulic cylinder is replenished with oil, the three-position four-way proportional directional valve on the left is in the left position and the three-position four-way proportional directional valve on the right is in the right position, so that the hydraulic oil in the right chamber of the hydraulic cylinder flows back to the hydraulic oil tank.

[0026] When the right chamber of the hydraulic cylinder is replenished with oil, the right three-position four-way proportional directional valve operates in the left position, and the left three-position four-way proportional directional valve operates in the right position, so that the hydraulic oil in the left chamber of the hydraulic cylinder flows back to the hydraulic oil tank.

[0027] When the left chamber of the hydraulic motor is unloading oil, the three-position four-way proportional directional valve on the left operates in the right position, and the three-position four-way proportional directional valve on the right operates in the right position, so that the hydraulic oil in the right chamber of the hydraulic motor flows back to the hydraulic oil tank.

[0028] The system of this invention comprises four main parts: first, an actuator, which can employ multiple different types of hydraulic actuators, such as hydraulic cylinders and hydraulic motors, to realize the operational functions of related equipment; second, a hydraulic pump control component, consisting of a fixed-displacement hydraulic pump driven by a variable-speed servo motor and a three-position four-way directional valve; third, a parallel valve control circuit, consisting of a three-position four-way proportional directional valve; and fourth, a load-sensitive valve-controlled oil supply module, consisting of a variable-displacement hydraulic pump driven by an AC motor.

[0029] The system of this invention can be used to control multiple hydraulic actuators, each of which requires a set of hydraulic pump control components and a set of parallel valve control circuits.

[0030] This invention employs a model-based feedforward and feedback composite control method to control the motion of the actuator. The feedforward control quantity is calculated based on model characteristics and accounts for the main part of the total control quantity, while the feedback control quantity is related to the control error and accounts for a smaller part of the total control quantity. Moreover, it can be very small when the control accuracy is good. In terms of control method, a hydraulic pump control component is used to control the feedforward flow to achieve high energy efficiency. At the same time, a parallel valve control loop is used to control the feedback flow, thereby avoiding large energy losses while using the feedback control of the parallel valve control loop to ensure motion control accuracy. This method is particularly suitable for applications with high requirements for system energy efficiency and actuator dynamic response performance.

[0031] The system and its feedforward-feedback composite control method of the present invention mainly compensate the performance of the pump control system through parallel valve control loops, so as to realize high-performance motion control of the actuator in high dynamic application scenarios.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. This invention designs a multi-actuator open pump control system in the form of a servo motor driven quantitative pump. It uses a three-position four-way switch directional valve to control the direction of the pump's outlet flow. By controlling the speed of the servo motor, the hydraulic pump can be controlled to supply oil to the actuator, making full use of the high energy efficiency advantage of the volume control method of the pump control system.

[0034] 2. Based on open pump control, this invention adds a parallel valve control circuit, which can simultaneously control the flow rate into and out of the actuator. It utilizes the high-frequency response advantage of valve control to compensate for the slower dynamic characteristics of pump control.

[0035] 3. In terms of control methods, feedforward control usually accounts for the main part of the total control quantity. Using pump control to control this part of the flow is beneficial to the system's energy efficiency. Meanwhile, feedback control usually accounts for a smaller part, and can be very small when the control accuracy is good. This part of the flow is controlled by parallel valve control loops, which can not only use feedback to ensure control performance, but also avoid generating large energy losses. It is particularly suitable for applications with high requirements for system energy efficiency and actuator dynamic response performance. Attached Figure Description

[0036] Figure 1 This is a hydraulic schematic diagram of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the working method of the present invention under typical working conditions.

[0038] In the diagram: Hydraulic cylinders 1 and 2; Hydraulic motor 3; Three-position four-way directional valve 4; Fixed displacement hydraulic pump 5; Variable speed servo motor 6; Three-position four-way proportional directional valves 7-1 and 7-2; Variable displacement hydraulic pump 8; AC motor 9; Hydraulic oil 10. Detailed Implementation

[0039] The present invention will be described in detail below with reference to specific implementation examples. These examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way.

[0040] like Figure 1 As shown, the system includes a parallel execution hydraulic pump control module, a variable hydraulic pump 8, an AC motor 9, and a hydraulic oil tank 10; both the parallel execution hydraulic pump control module and the variable hydraulic pump 8 are connected to the hydraulic oil tank 10, and the AC motor 9 and the variable hydraulic pump 8 are electrically connected; the parallel execution hydraulic pump control module is mainly formed by several single-stage execution hydraulic pump control units connected in parallel.

[0041] The single-stage hydraulic pump control unit mainly consists of an actuator, a hydraulic pump control component, and a parallel valve control circuit. The input end of the hydraulic pump control component is connected to the output end of the hydraulic oil tank 10, and the output end of the hydraulic pump control component is connected to the input end of the actuator. The two ends of the parallel valve control circuit group are connected to the hydraulic oil tank 10 and the actuator, respectively. The parallel valve control circuit group can be used to control the flow direction of hydraulic oil in the actuator.

[0042] The hydraulic pump control component includes a three-position four-way directional valve 4, a fixed displacement hydraulic pump 5, and a variable speed servo motor 6. The fixed displacement hydraulic pump 5 and the variable speed servo motor 6 are electrically connected. The fixed displacement hydraulic pump 5 is driven by the variable speed servo motor 6, which controls the speed of the fixed displacement hydraulic pump 5. The suction port of the fixed displacement hydraulic pump 5 is connected to the outlet port of the hydraulic oil tank 10. The outlet port of the fixed displacement hydraulic pump 5 is connected to the inlet port P of the three-position four-way directional valve 4. The outlet port of the three-position four-way directional valve 4 is connected to the hydraulic oil chamber of the actuator, thus forming a hydraulic circuit from the oil tank 10 to the fixed displacement hydraulic pump 5 and then to the three-position four-way directional valve 4. The function of supplying oil to the actuator can be achieved by adjusting the speed of the variable speed servo motor 6. The hydraulic circuit functions of the hydraulic cylinder 1 and the hydraulic motor 3 of the actuator are consistent.

[0043] The parallel valve control circuit mainly consists of two three-position four-way proportional directional valves 7-1 and 7-2. One port of each three-position four-way proportional directional valve 7-1 and 7-2 is connected to the hydraulic oil chamber of the actuator, and the other port is connected to the output end of the variable pump 8 or the hydraulic oil tank 10. The three-position four-way proportional directional valves 7-1 and 7-2 are used to control the flow direction of hydraulic oil between the hydraulic oil tank 10 and the actuator. In specific implementation, the variable pump 8 and the hydraulic oil tank 10 are directly connected, that is, one port of the three-position four-way proportional directional valves 7-1 and 7-2 is indirectly connected to the hydraulic oil tank 10 through the variable pump 8 or directly connected to the hydraulic oil tank 10. Therefore, the three-position four-way proportional directional valves 7-1 and 7-2 can control the hydraulic oil flowing into and out of the actuator. The hydraulic circuit functions of the hydraulic cylinder 1 and the hydraulic motor 3 are consistent.

[0044] When the hydraulic oil chamber of the actuator is replenished with oil, the oil inlet P of the three-position four-way proportional directional valves 7-1 and 7-2 is connected to the oil outlet of the hydraulic oil tank 10 through the variable pump 8. The oil outlet of the three-position four-way proportional directional valves 7-1 and 7-2 is connected to the hydraulic oil chamber in the actuator that needs to be replenished with oil, so that the hydraulic oil in the hydraulic oil tank 10 flows sequentially through the variable pump 8 and the three-position four-way proportional directional valves 7-1 and 7-2 to the hydraulic oil chamber of the actuator.

[0045] When hydraulic oil flows out of the hydraulic oil chamber of the actuator, the return port T of the three-position four-way proportional directional valves 7-1 and 7-2 is connected to the hydraulic oil tank 10, and the inlet port of the three-position four-way proportional directional valves 7-1 and 7-2 is connected to the hydraulic oil chamber in the actuator that is about to discharge oil, so that the hydraulic oil in the hydraulic oil chamber of the actuator flows back to the hydraulic oil tank 10 through the three-position four-way proportional directional valves 7-1 and 7-2.

[0046] The actuator adopts one of hydraulic cylinders 1 and 2 and hydraulic motor 3. The number of actuators in the parallel hydraulic pump control module is unlimited, and the number of actuators, hydraulic pump control components and parallel valve control circuits is the same.

[0047] Each actuator can be directly supplied with oil by a fixed-displacement hydraulic pump 5. Each actuator can also be controlled through a parallel valve control circuit. Taking the hydraulic control method of hydraulic cylinders 1 and 2 as an example, the variable hydraulic pump 8 and the AC motor 9 form a load-sensitive valve control oil supply module to supply oil to the parallel valve control circuit. The variable pump 8 draws oil from the oil tank 10, and the oil outlet of the variable pump 8 is connected to the P port of the three-position four-way proportional directional valves 7-1 and 7-2. The T port of the three-position four-way proportional directional valves 7-1 and 7-2 is connected to the oil tank 10.

[0048] Both the hydraulic pump control unit and the parallel valve control circuit control the flow into the actuator, and the parallel valve control circuit can also control the flow out of the actuator.

[0049] The method of the present invention includes the following steps:

[0050] Step 1: First, connect the actuator and the fixed displacement hydraulic pump 5 through the three-position four-way switch directional valve 4, and control the working state of the three-position four-way switch directional valve 4 to make the actuator be in the preset forward motion state or reverse motion state.

[0051] Step 2: Then, the speed of the fixed displacement hydraulic pump 5 is controlled in real time by the variable speed servo motor 6, thereby controlling the flow rate of hydraulic oil from the hydraulic tank 10 to the actuator after passing through the fixed displacement hydraulic pump 5 and the three-position four-way switch directional valve 4.

[0052] Step 3: Next, according to the preset feedback control quantity, control the working state of the two three-position four-way proportional directional valves 7-1 and 7-2, thereby controlling the flow direction of hydraulic oil between the actuator and the hydraulic oil tank 10. During the process, the speed of the variable hydraulic pump 8 is controlled in real time by the AC motor 9, thereby controlling the flow rate of hydraulic oil from the hydraulic oil tank 10 to the actuator after passing through the variable hydraulic pump 8.

[0053] The precise control of hydraulic oil flow rate by the fixed displacement hydraulic pump 5 and the variable displacement hydraulic pump 8 enables precise regulation of the actuator's motion state.

[0054] In step 1, the specific operation of using the three-position four-way directional valve 4 to bring the actuator to the preset motion state is as follows:

[0055] If hydraulic cylinders 1 and 2 are in the forward motion state, that is, moving to the right, the three-position four-way switch directional valve 4 is working in the left position, and the quantitative hydraulic pump 5 controls the hydraulic oil to flow from the hydraulic oil tank 10 to the left chamber of hydraulic cylinders 1 and 2, so that the hydraulic rods of hydraulic cylinders 1 and 2 move to the right.

[0056] If hydraulic cylinders 1 and 2 are in the reverse motion state, that is, moving to the left, the three-position four-way switch directional valve 4 is working in the right position, and the quantitative hydraulic pump 5 controls the hydraulic oil to flow from the hydraulic oil tank 10 to the right chamber of hydraulic cylinders 1 and 2, so that the hydraulic rods of hydraulic cylinders 1 and 2 move to the left.

[0057] If the hydraulic motor 3 is in the forward motion state, the three-position four-way switch directional valve 4 is working in the left position, and the quantitative hydraulic pump 5 controls the hydraulic oil to flow from the hydraulic oil tank 10 to the left chamber of the hydraulic motor 3.

[0058] In step 3, the specific method for controlling the hydraulic oil flow direction based on the three-position four-way proportional directional valves 7-1 and 7-2 is as follows:

[0059] When the left chambers of hydraulic cylinders 1 and 2 are replenished with oil, the three-position four-way proportional directional valve 7-1 on the left is in the left position and the three-position four-way proportional directional valve 7-2 on the right is in the right position, so that the hydraulic oil in the right chambers of hydraulic cylinders 1 and 2 flows back to the hydraulic oil tank 10.

[0060] When the right chambers of hydraulic cylinders 1 and 2 are replenished with oil, the right three-position four-way proportional directional valve 7-2 operates in the left position, and the left three-position four-way proportional directional valve 7-1 operates in the right position, so that the hydraulic oil in the left chambers of hydraulic cylinders 1 and 2 flows back to the hydraulic oil tank 10.

[0061] When the left chamber of the hydraulic motor 3 discharges oil, the left three-position four-way proportional directional valve 7-1 operates in the right position, and the right three-position four-way proportional directional valve 7-2 operates in the right position, so that the hydraulic oil in the right chamber of the hydraulic motor 3 flows back to the hydraulic oil tank 10.

[0062] First, aiming at accurate trajectory tracking of the actuator, a model-based feedforward and feedback composite control quantity is designed, which includes two parts: feedforward control quantity and feedback control quantity. The feedforward control quantity accounts for a larger proportion, while the feedback control quantity accounts for a smaller proportion, and the feedback control quantity has a greater impact on the closed-loop control performance. Second, considering the high energy efficiency of using a variable speed motor to drive a hydraulic pump to control the actuator, a hydraulic pump control component is used to implement the feedforward control quantity, providing flow to the actuator in a highly energy-efficient manner. At the same time, considering the good dynamic performance of the proportional directional valve, a parallel valve control loop is used to implement the feedback control quantity, ensuring motion control accuracy while avoiding significant energy loss.

[0063] Figure 2 This is a schematic diagram illustrating the working principle of the present invention under typical operating conditions, combined with... Figure 2 The implementation method of the feedforward-feedback composite control method for the multi-actuator hydraulic pump control system provided by the present invention is described. Figure 2 The feasible operating positions of the three actuators (including two hydraulic cylinders 1 and 2 and a hydraulic motor 3) are shown for the three-position four-way switching directional valve 4 and the three-position four-way proportional directional valves 7-1 and 7-2.

[0064] (1) The first single-stage hydraulic pump control unit uses hydraulic cylinder 1. The working state of the first single-stage hydraulic pump control unit is as follows: Hydraulic cylinder 1 is in the typical working condition of forward motion (valve compensation). The three-position four-way switch directional valve 4 is working in the left position. The variable speed servo motor 6 drives the fixed quantity hydraulic pump 5 to control the flow of hydraulic oil to the left chamber of hydraulic cylinder 1. The speed control signal of the variable speed servo motor 6 is calculated based on the feedforward control quantity. At the same time, considering that the dynamic response of the fixed quantity hydraulic pump 5 is relatively slow, the actual flow may lag behind the required flow, resulting in control error. At this time, the three-position four-way proportional directional valve 7-1 is controlled in the left position, and oil is replenished to the left chamber of hydraulic cylinder 1 according to the feedback control quantity. The three-position four-way proportional directional valve 7-2 is working in the right position so that the flow of the right chamber of hydraulic cylinder 1 flows back to the oil tank 10.

[0065] (2) The second single-stage hydraulic pump control unit uses hydraulic cylinder 2. The working state of the second single-stage hydraulic pump control unit is as follows: Hydraulic cylinder 2 is in the typical working condition of reverse motion (valve compensation). The three-position four-way switch directional valve 4 is working in the right position. The variable speed servo motor 6 drives the fixed quantity hydraulic pump 5 to control the flow of hydraulic oil to the right chamber of hydraulic cylinder 2. The speed control signal of the variable speed servo motor 6 is calculated based on the feedforward control quantity. At the same time, considering that the dynamic response of the fixed quantity hydraulic pump 5 is relatively slow, the actual flow may lag behind the required flow, resulting in control error. At this time, the three-position four-way proportional directional valve 7-2 is controlled in the left position. Based on the feedback control quantity, oil is replenished to the right chamber of hydraulic cylinder 2. The three-position four-way proportional directional valve 7-1 is working in the right position so that the flow of the left chamber of hydraulic cylinder 2 flows back to the oil tank 10.

[0066] (3) The third single-stage hydraulic pump control unit uses a hydraulic motor 3. The working state of the third single-stage hydraulic pump control unit is as follows: the hydraulic motor 3 is in the typical working condition of forward motion (valve unloading oil), the three-position four-way switch directional valve 4 is working in the left position, the variable speed servo motor 6 drives the fixed quantity hydraulic pump 5 to control the flow of hydraulic oil to the left chamber of the hydraulic motor 3, the speed control signal of the variable speed servo motor 6 is calculated based on the feedforward control quantity, and at the same time, considering that the dynamic response of the fixed quantity hydraulic pump 5 is relatively slow, it may produce overshoot, resulting in the actual flow rate being greater than the required flow rate, and producing overshoot control error. At this time, the three-position four-way proportional directional valve 7-1 is controlled in the right position, and the oil is unloaded from the left chamber of the hydraulic motor 3 according to the feedback control quantity. The three-position four-way proportional directional valve 7-2 is working in the right position so that the flow of the right chamber of the hydraulic motor 3 flows back to the oil tank 10.

[0067] This invention addresses the issues of slow response and low accuracy in pump-controlled systems. In system design, it compensates for the dynamic response performance of the pump by adding a parallel valve control loop. In terms of control method, it adopts a composite control approach of feedforward and feedback, using the pump to control the feedforward flow and the valve to control the feedback flow to achieve motion servo control of the hydraulic actuator.

[0068] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A multi-actuator hydraulic pump control system with parallel valve control circuits, characterized in that: It includes a parallel execution hydraulic pump control module, a variable hydraulic pump (8), an AC motor (9), and a hydraulic oil tank (10); the parallel execution hydraulic pump control module and the variable hydraulic pump (8) are both connected to the hydraulic oil tank (10), and the AC motor (9) and the variable hydraulic pump (8) are electrically connected; the parallel execution hydraulic pump control module is mainly formed by several single-stage execution hydraulic pump control units connected in parallel; The single-stage hydraulic pump control unit mainly consists of an actuator, a hydraulic pump control component, and a parallel valve control circuit. The input end of the hydraulic pump control component is connected to the output end of the hydraulic oil tank (10), and the output end of the hydraulic pump control component is connected to the input end of the actuator. The two ends of the parallel valve control circuit group are respectively connected to the hydraulic oil tank (10) and the actuator. The parallel valve control circuit group is used to control the flow direction of hydraulic oil in the actuator. The hydraulic pump control component includes a three-position four-way switch directional valve (4), a fixed displacement hydraulic pump (5), and a variable speed servo motor (6); the fixed displacement hydraulic pump (5) and the variable speed servo motor (6) are electrically connected, the variable speed servo motor (6) is used to control the speed of the fixed displacement hydraulic pump (5), the oil inlet of the fixed displacement hydraulic pump (5) is connected to the oil outlet of the hydraulic oil tank (10), the oil outlet of the fixed displacement hydraulic pump (5) is connected to the oil inlet P of the three-position four-way switch directional valve (4), and the oil outlet of the three-position four-way switch directional valve (4) is connected to the hydraulic oil chamber of the actuator; The parallel valve control circuit mainly consists of two three-position four-way proportional directional valves (7-1, 7-2). One port of each three-position four-way proportional directional valve (7-1, 7-2) is connected to the hydraulic oil chamber of the actuator, and the other port is connected to the output end of the variable hydraulic pump (8) or the hydraulic oil tank (10). The three-position four-way proportional directional valves (7-1, 7-2) are used to control the flow direction of hydraulic oil between the hydraulic oil tank (10) and the actuator.

2. The multi-actuator hydraulic pump control system with parallel valve control circuit according to claim 1, characterized in that: When the hydraulic oil chamber of the actuator is replenished with oil, the oil inlet P of the three-position four-way proportional directional valve (7-1, 7-2) is connected to the oil outlet of the hydraulic oil tank (10) through the variable hydraulic pump (8), and the oil outlet of the three-position four-way proportional directional valve (7-1, 7-2) is connected to the hydraulic oil chamber in the actuator that needs to be replenished with oil, so that the hydraulic oil in the hydraulic oil tank (10) flows to the hydraulic oil chamber of the actuator through the variable hydraulic pump (8) and the three-position four-way proportional directional valve (7-1, 7-2) in sequence. When hydraulic oil flows out of the hydraulic oil chamber of the actuator, the return port T of the three-position four-way proportional directional valve (7-1, 7-2) is connected to the hydraulic oil tank (10), and the inlet of the three-position four-way proportional directional valve (7-1, 7-2) is connected to the hydraulic oil chamber in the actuator that is to be drained, so that the hydraulic oil in the hydraulic oil chamber of the actuator flows back to the hydraulic oil tank (10) through the three-position four-way proportional directional valve (7-1, 7-2).

3. The multi-actuator hydraulic pump control system with parallel valve control circuit according to claim 1, characterized in that: The actuator is one of a hydraulic cylinder (1, 2) and a hydraulic motor (3). The number of actuators in the parallel hydraulic pump control module is unlimited, and the number of actuators, hydraulic pump control components and parallel valve control circuits is the same.

4. A hydraulic flow control method using any of the systems described in claims 1-3, characterized in that, Includes the following steps: Step 1: First, connect the actuator and the fixed displacement hydraulic pump (5) through the three-position four-way switch directional valve (4) and control the working state of the three-position four-way switch directional valve (4) to make the actuator be in the preset motion state. Step 2: Then, the speed of the fixed-displacement hydraulic pump (5) is controlled in real time by the variable speed servo motor (6), thereby controlling the flow rate of hydraulic oil from the hydraulic tank (10) into the actuator after passing through the fixed-displacement hydraulic pump (5) and the three-position four-way switch directional valve (4); Step 3: Next, according to the preset feedback control quantity, control the working state of the two three-position four-way proportional directional valves (7-1, 7-2), thereby controlling the flow direction of hydraulic oil between the actuator and the hydraulic oil tank (10). During the process, the speed of the variable hydraulic pump (8) is controlled in real time by the AC motor (9), thereby controlling the flow rate of hydraulic oil from the hydraulic oil tank (10) to the actuator after passing through the variable hydraulic pump (8). The precise control of the hydraulic oil flow rate is achieved by using a fixed-displacement hydraulic pump (5) and a variable-displacement hydraulic pump (8) to precisely regulate the motion state of the actuator.

5. A hydraulic flow control method for a multi-actuator hydraulic pump control system with parallel valve control circuits according to claim 4, characterized in that: In step 1, the specific operation of putting the actuator into the preset motion state through the three-position four-way directional valve (4) is as follows: If the hydraulic cylinder (1,2) is in the forward motion state, the three-position four-way switch reversing valve (4) is controlled to work in the left position, and the quantitative hydraulic pump (5) controls the hydraulic oil to flow from the hydraulic oil tank (10) to the left chamber of the hydraulic cylinder (1,2), and the hydraulic rod of the hydraulic cylinder (1,2) moves to the right. If the hydraulic cylinder (1,2) is in the reverse motion state, the three-position four-way switch reversing valve (4) is controlled to work in the right position, and the quantitative hydraulic pump (5) controls the hydraulic oil to flow from the hydraulic oil tank (10) to the right chamber of the hydraulic cylinder (1,2), and the hydraulic rod of the hydraulic cylinder (1,2) moves to the left. If the hydraulic motor (3) is in the forward motion state, the three-position four-way switch reversing valve (4) is controlled to work in the left position, and the quantitative hydraulic pump (5) controls the hydraulic oil to flow from the hydraulic oil tank (10) to the left chamber of the hydraulic motor (3).

6. A hydraulic flow control method for a multi-actuator hydraulic pump control system with a parallel valve control circuit according to claim 4, characterized in that: In step 3, the specific method for controlling the hydraulic oil flow direction based on the three-position four-way proportional directional valves (7-1, 7-2) is as follows: When the left chamber of the hydraulic cylinder (1, 2) is replenished with oil, the left three-position four-way proportional directional valve (7-1) is controlled to work in the left position, and the right three-position four-way proportional directional valve (7-2) is controlled to work in the right position, so that the hydraulic oil in the right chamber of the hydraulic cylinder (1, 2) flows back to the hydraulic oil tank (10). When the right chamber of the hydraulic cylinder (1, 2) is replenished with oil, the right three-position four-way proportional directional valve (7-2) is controlled to work in the left position, and the left three-position four-way proportional directional valve (7-1) is controlled to work in the right position, so that the hydraulic oil in the left chamber of the hydraulic cylinder (1, 2) flows back to the hydraulic oil tank (10). When the left chamber of the hydraulic motor (3) discharges oil, the three-position four-way proportional directional valve (7-1) on the left is controlled to work in the right position, and the three-position four-way proportional directional valve (7-2) on the right is controlled to work in the right position, so that the hydraulic oil in the right chamber of the hydraulic motor (3) flows back to the hydraulic oil tank (10).

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