A control system and control method based on an open variable pump control switch system

Abstract

The application discloses a control system and a control method based on an open variable pump control switch system, and comprises a variable pump, an oil inlet of the variable pump is connected with an oil tank, and an oil outlet of the variable pump is divided into two oil liquid paths, one of which leads to a feedback system, and the other of which leads to a switch system through a pressure compensation valve and a throttle; the oil liquid from the pressure compensation valve is also divided into a path which flows through an electromagnetic valve and a throttle valve, and the oil liquid in the path flows into a spring cavity of the pressure compensation valve in part and flows through a check valve and a feedback oil path of the feedback system to converge to a variable mechanism of the variable pump, and the oil liquid is divided into a path which flows back to the oil tank through a constant flow valve. The application provides a hydraulic system design method for stably supplying oil from a single pump to multiple systems, and the loop is simple; the application can still provide stable flow under the condition that an external load changes, and can guarantee stable moving speed of a hydraulic cylinder and stable rotating speed of a motor.

Description

Technical Field

[0001] This invention discloses a control system and control method based on an open variable pump control switch system, which relates to the field of constant flow control technology. Background Technology

[0002] With the development of technology, the method of using a single pump to supply oil to multiple systems to improve work efficiency and optimize system structure is being used more and more. A single pump can not only supply oil to a single system, but also supply oil to multiple systems simultaneously. Existing technical solutions control the pump's oil supply to the switching system by controlling the on / off state of a two-position two-way solenoid valve; however, this cannot guarantee that the pump's oil supply flow to the system is not affected by external loads, thus failing to provide a stable oil source flow. Summary of the Invention

[0003] To address the deficiencies in the aforementioned background technology, this invention provides a control system and control method based on an open variable pump control switch system, which controls the variable pump to selectively supply oil to the system while ensuring that the flow rate is not affected by the external load.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a control system based on an open variable pump control switch system, comprising: an oil tank, a variable pump, a constant flow valve, a throttle valve, a pressure compensation valve, a throttle, a switch system, a solenoid valve, a check valve, and a feedback system;

[0005] The inlet of the variable pump is connected to the oil tank, and the outlet of the variable pump splits into two oil paths. One path leads to the feedback system, and the other path passes through the pressure compensation valve and the throttle valve to the switching system.

[0006] The oil from the pressure compensation valve also flows through a solenoid valve and a throttle valve. Part of this oil flows into the spring chamber of the pressure compensation valve, and part flows through a check valve to merge with the feedback oil circuit of the feedback system and flows to the variable mechanism of the variable pump. Another part of the oil flows back to the oil tank through the constant flow valve. The variable pump has a variable mechanism. The spring chamber of the variable mechanism is connected to the inlet of the constant flow valve, the LS port of the feedback system, and the closed end of the check valve. The springless chamber of the variable mechanism is connected to the outlet of the variable pump.

[0007] Furthermore, the throttle includes a throttle orifice, which is used to cooperate with a pressure compensation valve to provide a stable flow rate. The form of the throttle is not limited to an orifice; as long as it can generate a pressure drop, or pressure loss, it can be regarded as a throttle orifice.

[0008] Furthermore, the solenoid valve includes a two-position three-way solenoid valve.

[0009] Furthermore, the main return port of the solenoid valve is connected to the oil tank; the main inlet port of the solenoid valve is connected to the outlet port of the throttle valve; and the working port of the solenoid valve is connected to the inlet port of the throttle valve.

[0010] Furthermore, a portion of the oil from the pressure compensation valve flows into its control chamber.

[0011] Furthermore, the switching system includes: a system controlled by a switching valve. 。

[0012] Furthermore, the feedback system includes a system with load feedback control.

[0013] A control method based on an open variable pump control switching system is provided, wherein when the solenoid valve is not energized, the pressure compensation valve is closed, and no oil flows through to the switching system.

[0014] Furthermore, when the solenoid valve is energized and the LS signal pressure in the feedback oil circuit is less than the oil pressure leading to the switching system, the oil pressure of the switching system reaches the variable mechanism of the variable pump through the solenoid valve, throttle valve, and check valve. The displacement of the variable pump is adjusted so that the output pressure of the variable pump is greater than the oil pressure of the switching system by a constant value. Under the action of the constant flow valve, throttle valve, pressure compensation valve, and throttle device, the flow rate to the switching system is a constant value.

[0015] Furthermore, when the solenoid valve is energized and the LS signal pressure in the feedback oil circuit is greater than the oil pressure leading to the switching system, the LS signal pressure in the feedback oil circuit goes to the variable mechanism of the variable pump, and the oil pressure in the switching system goes to the spring chamber of the pressure compensation valve through the solenoid valve and the throttle valve. Under the action of the pressure compensation valve and the throttle, the flow rate to the switching system is a constant value.

[0016] Beneficial effects: This invention provides a hydraulic system design method for stable oil supply from a single pump to multiple systems, with a simple circuit; this invention can still provide a stable flow rate under varying external loads, ensuring a stable moving speed of the hydraulic cylinder and a stable rotation speed of the motor; it also makes reasonable use of the engine's output power, improving work efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0018] The implementation of the technical solution will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] like Figure 1The embodiment shown provides a control system based on an open variable pump control switching system, including: an oil tank 1, a variable pump 2, a constant flow valve 3, a throttle valve 4, a pressure compensation valve 5, a throttle 6, a switching system 7, a solenoid valve 8, a check valve 9, and a feedback system 10.

[0020] The inlet of variable pump 2 is connected to oil tank 1. The outlet of variable pump 2 splits into two oil paths, one of which leads to feedback system 10, and the other path leads to switching system 7 through pressure compensation valve 5 and throttle valve 6.

[0021] The oil from the pressure compensation valve 5 is also split into two streams: one flows through the solenoid valve 8 and the throttle valve 4. Part of this oil flows into the spring chamber of the pressure compensation valve 5, and the other flows through the check valve 9 to merge with the feedback oil path of the feedback system 10 and flow to the variable mechanism of the variable pump 2. Another stream of oil flows back to the oil tank 1 through the constant flow valve 3. The spring chamber of the variable mechanism is connected to the inlet of the constant flow valve 3, the LS port of the feedback system 10, and the closed end of the check valve 9. The springless chamber of the variable mechanism is connected to the outlet of the variable pump 2. The LS signal pressure feedback at the LS port is the external load pressure of the feedback system 10.

[0022] The one-way valve 9 is used to isolate the influence of the load feedback signal of the feedback system 10 on the pressure compensation valve 5;

[0023] The throttle 6 includes a throttle orifice; the solenoid valve 8 includes a two-position three-way solenoid valve.

[0024] The main return port T of the solenoid valve 8 is connected to the oil tank 1; the main inlet port P of the solenoid valve 8 is connected to the outlet end of the throttle valve 6; and the working port A of the solenoid valve 8 is connected to the inlet port of the throttle valve 4.

[0025] The switching system 7 includes: a system controlled by a switching valve; and a system that uses only a switching valve to control the action of an actuator. A switching valve is a valve whose control quantity is a switching quantity, such as a three-position four-way solenoid valve controlling the action of an actuator.

[0026] The feedback system 10 includes: a system with load feedback control; and a system that controls the oil flow to the actuator by combining a pressure compensation valve with other valves, which is only related to the valve opening of other valves and is independent of the load, such as an LS system using pre-valve compensation and a LUDV system using post-valve compensation.

[0027] A control method based on an open variable pump control switching system:

[0028] When the solenoid valve 8 is not energized, the variable pump 2 supplies the required oil to the feedback system 10; at the same time, the pressure compensation valve 5 is closed, and no oil goes to the switching system 7; the pressurized oil passes through the pressure compensation valve 5 and acts on the control chamber of the pressure compensation valve 5. Since there is no pressure in the spring chamber of the pressure compensation valve 5, the pressure in the control chamber of the pressure compensation valve 5 is greater than the spring force of the spring chamber, which will cause the pressure compensation valve 5 to close, so that no oil passes through this branch.

[0029] When the two-position three-way solenoid valve 8 is energized, the variable pump 2 simultaneously supplies oil to the feedback system 10 and the switching system 7. Due to the different loads of these two systems, the LS signal pressure fed back by the feedback system 10 is different from the pressure leading to the switching system 7, as detailed below.

[0030] First scenario:

[0031] When solenoid valve 8 is energized, the external load of feedback system 10 is less than the external load of switching system 7, and the LS signal pressure in the feedback oil circuit is less than the oil pressure leading to switching system 7, the oil pressure of switching system 7 reaches the variable mechanism of variable pump 2 via solenoid valve 8, throttle valve 4, and check valve 9. The displacement of variable pump 2 is adjusted so that the output pressure of variable pump 2 is greater than the oil pressure of switching system 7 by a constant value. Under the action of constant flow valve 3, throttle valve 4, pressure compensation valve 5, and throttle device 6, the flow rate to switching system 7 is a constant value.

[0032] When the external load on the switching system 7 changes, the hydraulic pressure of the switching system 7 acts on the variable mechanism of the variable pump 2. This pressure is compared with the outlet pressure of the variable pump 2. That is, the outlet pressure of the variable pump 2 is equal to the sum of the hydraulic pressure of the switching system 7 and the spring force of the variable mechanism, so that the output pressure of the variable pump 2 is always greater than the hydraulic pressure of the switching system 7 by x1 MPa (x1 is a constant value).

[0033] When the external load on the switching system 7 increases, the displacement of the variable pump 2 increases due to the action of its variable mechanism, resulting in a larger output flow rate. As the output flow rate of the variable pump 2 increases, the flow rate passing through the pressure compensation valve 5 and the throttle valve 6 also increases. Since the oil pressure in the switching system 7 does not change with the increase in flow rate, and the opening of the throttle valve 6 and the valve port of the pressure compensation valve 5 remain unchanged, the outlet pressure of the variable pump 2 increases, leading to an increase in the outlet pressure of the variable pump 2. This increased outlet pressure of the variable pump 2, acting on its variable mechanism, causes the variable pump... As the displacement of pump 2 decreases, the flow rate output by pump 2 decreases. As the flow rate output by pump 2 decreases, the flow rate passing through pressure compensation valve 5 and throttle valve 6 also decreases. Since the oil pressure of switching system 7 does not change with the decrease in flow rate and the opening of throttle valve 6 and the valve port of pressure compensation valve 5 remain unchanged, the outlet pressure of pump 2 decreases. The above process is repeated continuously to achieve the following balance: because the spring force of the variable mechanism of pump 2 tends to a constant value, the pressure output by pump 2 is always greater than the oil pressure of switching system 7 by x1 MPa (x1 is a constant value).

[0034] Conversely, when the external load on the switching system 7 decreases, the displacement of the variable pump 2 decreases due to the action of its variable mechanism, resulting in a smaller output flow. Because the output flow of the variable pump 2 decreases, the flow through the pressure compensation valve 5 and the throttle valve 6 also decreases. Since the oil pressure in the switching system 7 does not change with the decrease in flow and the opening of the throttle valve 6 and the valve port of the pressure compensation valve 5 remain unchanged, the outlet pressure of the variable pump 2 decreases, leading to a further decrease in the outlet pressure of the variable pump 2. This decrease in outlet pressure of the variable pump 2, acting on its variable mechanism, causes the variable pump to... As the displacement of pump 2 increases, the output flow of variable pump 2 increases. Due to the increased output flow of variable pump 2, the flow through pressure compensation valve 5 and throttle valve 6 also increases. Since the oil pressure of switching system 7 does not change with the increase in flow and the opening of throttle valve 6 and the valve port of pressure compensation valve 5 remain unchanged, the outlet pressure of variable pump 2 increases. The above process is repeated continuously, thereby achieving the following balance: because the spring force of the variable mechanism of variable pump 2 tends to a constant value, the output pressure of variable pump 2 is always greater than the oil pressure of switching system 7 by x1 MPa (x1 is a constant value).

[0035] Since the flow rate of the oil returning to the oil tank 1 through the constant flow valve 3 is constant, and the size of the throttle orifice of the throttle valve 4 remains unchanged, the flow rate through the throttle valve 4 is constant, and the pressure difference across the throttle valve 4 is a constant value a MPa. Under the action of the pressure compensation valve 5, the pressure after the pressure compensation valve 5 is (x2-a) MPa greater than the oil pressure of the switching system 7 (x2 is the spring pressure of the pressure compensation valve 5), so the pressure difference across the pressure compensation valve 5 is (x1-x2+a) MPa, and the pressure difference across the throttle valve 6 is (x2-a) MPa. Since the openings of the pressure compensation valve 5 and the throttle valve 6 remain unchanged, the flow rate to the switching system 7 is constant and is not affected by the external load.

[0036] Because the pressure after pressure compensation valve 5 acts on the control chamber of pressure compensation valve 5, the oil pressure of switching system 7 enters the spring chamber of pressure compensation valve 5 through solenoid valve 8 and throttle valve 4, and the pressure in the control chamber is equal to the sum of the pressure in the spring chamber and the spring force. When the load increases, the pressure in the spring chamber increases, the valve port of pressure compensation valve 5 increases, and the pressure after pressure compensation valve 5 increases. Conversely, when the load decreases, the pressure in the spring chamber decreases, the valve port of pressure compensation valve 5 decreases, and the pressure after pressure compensation valve 5 decreases. That is, the pressure after pressure compensation valve 5 is greater than the oil pressure of switching system 7 by x2MPa (x2 is the spring pressure of pressure compensation valve 5).

[0037] The second scenario:

[0038] When the solenoid valve 8 is energized, the external load of the feedback system 10 is greater than the external load of the switching system 7, and the LS signal pressure of the feedback oil circuit is greater than the oil pressure leading to the switching system 7, the LS signal pressure of the feedback oil circuit goes to the variable mechanism of the variable pump 2, and the oil pressure of the switching system 7 goes to the spring chamber of the pressure compensation valve 5 through the solenoid valve 8 and the throttle valve 4. Under the action of the pressure compensation valve 5 and the throttle valve 6, the flow rate to the switching system 7 is a constant value.

[0039] The LS signal pressure in the feedback oil circuit is greater than the oil pressure leading to the switching system. The feedback LS signal pressure goes to the feedback mechanism of the variable pump 2. The oil pressure in the switching system 7 goes to the spring chamber of the pressure compensation valve 5 through the solenoid valve 8 and the throttle valve 4. Under the action of the pressure compensation valve 5, the pressure difference across the throttle valve 6 is x2MPa (x2 is the spring pressure of the pressure compensation valve 5). Since the opening of the throttle valve 6 remains unchanged, the flow rate to the switching system 7 is a constant and is not affected by the external load.

[0040] Because the pressure after pressure compensation valve 5 acts on the control chamber of pressure compensation valve 5, the oil pressure of switching system 7 enters the spring chamber of pressure compensation valve 5 through solenoid valve 8 and throttle valve 4, and the control chamber pressure is equal to the sum of spring chamber pressure and spring force. When the load of switching system increases, the spring chamber pressure increases, the valve port of pressure compensation valve 5 increases, and the pressure after pressure compensation valve 5 increases. Conversely, when the switch load decreases, the spring chamber pressure decreases, the valve port of pressure compensation valve 5 decreases, and the pressure after pressure compensation valve 5 decreases. That is, the pressure after pressure compensation valve 5 is greater than the oil pressure of switching system 7 by x2MPa (x2 is the spring pressure of pressure compensation valve 5).

[0041] Therefore, at this time, the output flow of variable pump 2 is controlled by feedback system 10. However, due to the presence of pressure compensation valve 5 and throttle valve 6, the flow through switching system 7 is a constant value and is not affected by external load. It is only related to the spring force of pressure compensation valve 5.

[0042] This invention provides a hydraulic system design method for stable oil supply from a single pump to multiple systems, with a simple circuit. This invention can still provide a stable flow rate under varying external loads, ensuring a stable moving speed of the hydraulic cylinder and a stable rotation speed of the motor; it also makes reasonable use of the engine's output power, improving work efficiency.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control system for controlling an open center variable pump control switch system, characterized by, include: Oil tank (1), variable pump (2), constant flow valve (3), throttle valve (4), pressure compensation valve (5), throttle (6), switching system (7), solenoid valve (8), check valve (9) and feedback system (10). The inlet of the variable pump (2) is connected to the oil tank (1), and the outlet of the variable pump (2) splits into two oil paths. One path leads to the feedback system (10), and the other path passes through the pressure compensation valve (5) and the throttle (6) to the switching system (7). The oil coming out of the throttle valve (6) is also divided into two streams that flow through the solenoid valve (8) and the throttle valve (4). Part of this oil flows into the spring chamber of the pressure compensation valve (5), and part flows through the check valve (9) and merges with the feedback oil path of the feedback system (10) to flow into the variable mechanism of the variable pump (2). A separate stream of oil flows back to the oil tank (1) through the constant flow valve (3).

2. The control system of claim 1, wherein, The throttle (6) includes a throttle orifice for cooperating with the pressure compensation valve (5) to provide a stable flow rate.

3. The control system of claim 1, wherein, The solenoid valve (8) includes: a two-position three-way solenoid valve.

4. The control system based on an open variable pump control switch system according to claim 3, characterized in that, The main return port of the solenoid valve (8) is connected to the oil tank (1); the main inlet port of the solenoid valve (8) is connected to the outlet of the throttle valve (6); and the working port of the solenoid valve (8) is connected to the inlet of the throttle valve (4).

5. The control system of claim 3, wherein, The oil from the pressure compensation valve (5) flows into its control chamber.

6. The control system of claim 1, wherein, The switching system (7) includes a system controlled by a switching valve.

7. The control system of claim 1, wherein, The feedback system (10) includes: a system with load feedback control.

8. A control method for an open variable pump control switch system based on a control system according to any one of claims 1 to 7, characterized in that, When the solenoid valve (8) is not energized, the pressure compensation valve (5) closes, and no oil flows through to the switching system (7).

9. The control method based on an open variable pump control switch system according to claim 8, characterized in that, When the solenoid valve (8) is energized and the LS signal pressure of the feedback oil circuit is less than the oil pressure leading to the switching system (7), the oil pressure of the switching system (7) reaches the variable mechanism of the variable pump (2) through the solenoid valve (8), the throttle valve (4) and the check valve (9), and adjusts the displacement of the variable pump (2) so that the pressure output by the variable pump (2) is greater than the oil pressure of the switching system (7) by a constant value. Under the action of the constant flow valve (3), the throttle valve (4), the pressure compensation valve (5) and the throttle (6), the flow rate to the switching system (7) is a constant value.

10. The control method based on an open variable pump control switch system according to claim 8, characterized in that, When the solenoid valve (8) is energized and the LS signal pressure of the feedback oil circuit is greater than the oil pressure leading to the switching system (7), the LS signal pressure of the feedback oil circuit goes to the variable mechanism of the variable pump (2), and the oil pressure of the switching system (7) goes to the spring chamber of the pressure compensation valve (5) through the solenoid valve (8) and the throttle valve (4). Under the action of the pressure compensation valve (5) and the throttle valve (6), the flow rate to the switching system (7) is a constant value.

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