Positive flow hydraulic system based on load-sensitive electrically-controlled pump

Abstract

The application belongs to the field of engineering machinery, and particularly relates to a positive flow hydraulic system based on a load-sensitive electric control pump, which comprises a steering cylinder, a steering device for controlling the action of the steering cylinder, a working cylinder, a multi-way valve for controlling the action of the working cylinder, a reversing valve, a priority valve, and a load-sensitive electric control pump and an electric control pump which are both in communication with a hydraulic oil tank, the priority valve comprises a first working position, a second working position and a control oil path, the control oil path of the priority valve is used for switching the valve position of the priority valve, the oil inlet of the steering device is connected with the steering oil port of the priority valve, the oil inlet of the steering device is in fluid communication with the load-sensitive electric control pump through the priority valve in the first working position, the oil inlet of the multi-way valve is connected with the working oil port of the priority valve, and the oil inlet of the multi-way valve is in fluid communication with the load-sensitive electric control pump through the priority valve in the second working position. The application introduces the load-sensitive electric control pump to control the flow of the steering pump, greatly reduces the flow loss, and achieves a good energy-saving effect.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery, specifically relating to a positive flow hydraulic system based on a load-sensitive electronically controlled pump. Background Technology

[0002] Most current loader steering hydraulic systems are load-sensitive steering systems. The steering gear outputs a control signal to a priority valve to control the flow rate to the steering system. To improve energy efficiency, the steering pump uses a load-sensitive variable displacement pump, which outputs energy on demand, eliminating unnecessary energy loss. However, some loader working hydraulic systems use an electro-hydraulic system with positive flow rate, depending on requirements. The working and steering systems operate independently, and the steering pump cannot be fully utilized. Using a large-displacement working pump requires significant installation space, increasing overall installation costs. Existing technology addresses these issues by integrating the steering pump as part of the working pump, improving its utilization rate, reducing the working pump's displacement, or reducing the number of working pumps. This reduces installation space requirements and lowers system installation costs. However, in electro-hydraulic systems with positive flow rate, the lack of a load-sensitive feedback signal prevents control of the steering pump's flow rate. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a positive flow hydraulic system based on a load-sensitive electronically controlled pump. By introducing load-sensitive control, the flow rate of the steering pump can be controlled, which can significantly reduce flow loss and achieve better energy-saving effect.

[0004] The present invention is achieved through the following technical solution: a positive flow hydraulic system based on a load-sensitive electronically controlled pump, comprising a steering cylinder, a steering gear for controlling the movement of the steering cylinder, a working cylinder, and a multi-way valve for controlling the movement of the working cylinder. The first working port and the second working port of the steering gear are respectively connected to the rod chamber and the rodless chamber of the steering cylinder. The first working port and the second working port of the multi-way valve are respectively connected to the rod chamber and the rodless chamber of the working cylinder. The return port of the steering gear and the return port of the multi-way valve are both connected to the hydraulic oil tank. The system also includes a directional valve, a priority valve, and a load-sensitive electronically controlled pump and an electronically controlled pump, both of which are connected to the hydraulic oil tank. The priority valve includes a first working position, a second working position, and a control oil circuit. The priority valve is provided with a control port that communicates with the control oil circuit. The control oil circuit is used to switch the valve position of the priority valve so that the priority valve is in one of the following positions: alone in the first working position, alone in the second working position, and in a position between the first working position and the second working position. The oil inlet of the steering gear is connected to the steering oil port of the priority valve, and the oil inlet of the steering gear is in fluid communication with the load-sensitive electronic pump through the priority valve in the first working position; the oil inlet of the multi-way valve is connected to the working oil port of the priority valve, and the oil inlet of the multi-way valve is in fluid communication with the load-sensitive electronic pump through the priority valve in the second working position, and the oil inlet of the multi-way valve is also in fluid communication with the electronic pump; The reversing valve includes a first position and a second position. When the reversing valve is in the first position, the load feedback port of the steering gear is connected to the control port of the load-sensitive electronic pump, and the control port of the priority valve is blocked, with the priority valve in the first working position. When the reversing valve is in the second position, the oil outlet of the load-sensitive electronic pump is connected to the control port of the load-sensitive electronic pump, and the control port of the priority valve is connected to the load feedback port of the steering gear. The working position of the priority valve depends on the pressure difference between the steering oil port of the priority valve and the steering gear. A first pressure sensor is provided at the load feedback port of the steering gear, and a second pressure sensor is provided at the oil outlet of the electronically controlled pump.

[0005] In some embodiments, the reversing valve has a first control terminal and a second control terminal, wherein: When the second control terminal of the reversing valve is energized, the reversing valve is controlled to be in the second working position. When the second control terminal of the reversing valve is de-energized, the reversing valve is in the first operating position under the control of the first control terminal.

[0006] In some embodiments, the priority valve further includes a relief valve connected to the control oil circuit, the inlet of the relief valve being connected to the control oil circuit of the priority valve, and the outlet of the relief valve being connected to the hydraulic oil tank.

[0007] The beneficial effects of this invention are as follows: When the machine is not in operation, both the load-sensitive electric control pump and the electric control pump output at their minimum displacement, with no intermediate energy loss; when the machine is only turning, the load-sensitive electric control pump is controlled by load sensitivity and outputs on demand, with the electric control pump outputting at its minimum displacement; when the machine is only working, both the load-sensitive electric control pump and the electric control pump are controlled by the electric control program and output on demand, with no unnecessary flow loss and no throttling energy loss; when the machine is turning and working simultaneously, the load-sensitive electric control pump outputs according to the greater of the turning demand and the working demand, while the electric control pump outputs according to the working demand, satisfying both the turning flow demand and the working flow demand. Attached Figure Description

[0008] Figure 1 This is a hydraulic schematic diagram of the present invention; In the diagram, 1. Hydraulic oil tank, 2. Load-sensitive electric pump, 3. Directional control valve, 4. First pressure sensor, 5. Priority valve, 5-1. Relief valve, 6. Steering gear, 7. Steering cylinder, 8. Working cylinder, 9. Multi-way valve. Implementation

[0009] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0010] like Figure 1 As shown, a positive flow hydraulic system based on a load-sensitive electronically controlled pump includes a steering gear 6, a steering cylinder 7, a working cylinder 8, and a multi-way valve 9. The steering gear 6 controls the movement of the steering cylinder 7. Specifically, the steering gear 6 includes an inlet port, a return port, a first working port, a second working port, and a load feedback port LS2. The first working port of the steering gear 6 is connected to the rodless chamber of the steering cylinder 7, the second working port of the steering gear 6 is connected to the rod chamber of the steering cylinder 7, and the return port of the steering gear 6 is connected to the hydraulic oil tank 1. The multi-way valve 9 controls the movement of the working cylinder 8. Specifically, the multi-way valve 9 includes an inlet port P2, a return port T2, a first working port A, and a second working port B. The return port T2 of the multi-way valve 9 is connected to the hydraulic oil tank 1, the first working port A of the multi-way valve 9 is connected to the rodless chamber of the working cylinder 8, and the second working port B of the multi-way valve 9 is connected to the rod chamber of the working cylinder 8.

[0011] The positive flow hydraulic system also includes a directional valve 3, a priority valve 5, a load-sensitive electric pump 2, and an electric pump 11. The priority valve 5 includes an inlet port P1, a steering port CF, a working port EF, and a control port LS1. The inlet port P1 of the priority valve 5 is connected to the outlet port of the load-sensitive electric pump 2; the steering port CF of the priority valve 5 is connected to the inlet port of the steering gear 6; the working port EF of the priority valve 5 is connected to the inlet port P2 of the multi-way valve 9; and the control port LS1 of the priority valve 5 is connected to the control circuit of the priority valve 5. The priority valve 5 includes a first working position, a second working position, and a control circuit. The control circuit is used to switch the valve position of the priority valve 5 so that the priority valve 5 is in one of the following positions: alone in the first working position, alone in the second working position, or in a position between the first and second working positions. When the priority valve 5 is in the first operating position alone, its inlet P1 is in fluid communication with the steering port CF. That is, the steering gear 6's inlet is in fluid communication with the load-sensitive electronic pump 2 through the priority valve 5 in the first operating position. The hydraulic oil supplied by the outlet of the load-sensitive electronic pump 2 is supplied to the steering gear 6's inlet via the priority valve 5. When the priority valve 5 is in the second operating position alone, its inlet P1 is in fluid communication with the working port EF. That is, the multi-way valve 9's inlet is in fluid communication with the load-sensitive electronic pump 2 through the priority valve 5 in the second operating position. The hydraulic oil supplied by the outlet of the load-sensitive electronic pump 2 is supplied to the multi-way valve 9's inlet P2 via the priority valve 5. When the priority valve 5 is in the position between the first working position and the second working position, its inlet P1 is simultaneously in fluid communication with both the steering port CF and the working port EF. The hydraulic oil supplied by the outlet of the load-sensitive electronic pump 2 will be supplied via the priority valve 5 to both the steering gear 6 inlet and the multi-way valve 9 inlet P2. The multi-way valve 9 inlet P2 is also in fluid communication with the outlet of the electronic pump 11.

[0012] The reversing valve 3 includes working port A1, working port A2, working port A3 and working port A4. Working port A1 of the reversing valve 3 is connected to the load feedback port LS2 of the steering gear 6, working port A2 of the reversing valve 3 is connected to the outlet of the load-sensitive electronic pump 2, working port A3 of the reversing valve 3 is connected to the control port LS0 of the load-sensitive electronic pump 2, and working port A4 of the reversing valve 3 is connected to the control port LS1 of the priority valve 5. The reversing valve 3 includes a first position and a second position. When the reversing valve 3 is in the first position, the load feedback port LS2 of the steering gear 6 is connected to the control port LS0 of the load-sensitive electronic pump 2, and the control port LS1 of the priority valve 5 is blocked. The priority valve 5 is in the first working position under the control pressure at both ends and the spring force. When the reversing valve 3 is in the second position, the oil outlet of the load-sensitive electronic pump 2 is connected to the control port LS0 of the load-sensitive electronic pump 2, and the control port LS1 of the priority valve 5 is connected to the load feedback port LS2 of the steering gear 6. The working position of the priority valve 5 depends on the pressure difference between the steering oil port of the priority valve 5 and the steering gear 6.

[0013] The valve position switching of the reversing valve 3 is controlled by its first control terminal and second control terminal. The first control terminal of the reversing valve 3 is spring-controlled, and the second control terminal is electromagnet-controlled. When the second control terminal of the reversing valve 3 is energized, the reversing valve 3 is controlled to be in the second position; when the second control terminal of the reversing valve 3 is de-energized, the reversing valve 3 is in the first position under the control of the first control terminal.

[0014] A first pressure sensor 4 is provided at the load feedback port of the steering gear 6. The first pressure sensor 4 is used to detect the pressure at the load feedback port LS2 of the steering gear 6 and feed it back to the controller. A second pressure sensor 10 is provided at the oil outlet of the electronically controlled pump 11. The second pressure sensor 10 is used to detect the pressure at the oil outlet of the electronically controlled pump 11 and feed it back to the controller.

[0015] The working principle of the positive flow hydraulic system based on the load-sensitive electronically controlled pump in this embodiment is as follows: 1. No Operation: The steering gear 6 has no operation signal, and the operation control output has no operation signal. After receiving the signal, the controller outputs a control signal, causing the electric pump 11 to output at its minimum displacement, and the reversing valve 3 to be de-energized. At this time, the reversing valve 3 is in the first working position. The load feedback port LS2 of the steering gear 6 is connected to the control port LS0 of the load-sensitive electric pump 2. The load feedback port LS2 of the steering gear 6 is connected to the internal return oil of the steering gear 6. The first pressure sensor 4 has no pressure signal feedback. The control port LS1 of the priority valve 5 is blocked. Under the control pressure at both ends and the spring force, the priority valve 5 is in the first working position, causing the electronic control part of the load-sensitive electric pump 2 to be energized and output at its maximum displacement. At this time, the load-sensitive electric pump 2 is in the load-sensitive control state. With the priority valve 5 in the first working position, the hydraulic oil supplied by the outlet of the load-sensitive electric pump 2 flows out through the steering oil port CF of the priority valve 5 and is cut off by the oil inlet of the steering gear 6. As the outlet pressure of the load-sensitive electric pump 2 gradually increases, it reaches the set pressure of the load-sensitive valve of the load-sensitive electric pump 2. Under the internal control, the load-sensitive electric pump 2 reduces the discharge capacity until the flow rate meets the internal leakage requirements. At this time, the flow rate is small, the pressure is low, and there is almost no energy loss in the middle position.

[0016] 2. When steering alone: ​​Steering gear 6 outputs a steering action signal, and the working operation output has no action signal. After receiving the signal, the controller outputs a control signal to make the electric pump 11 output at minimum displacement, and the reversing valve 3 is in a de-energized state. At this time, the reversing valve 3 is in the first working position. The load feedback port LS2 of the steering gear 6 is connected to the control port LS0 of the load-sensitive electric pump 2, and the load feedback port LS2 of the steering gear 6 is connected to the steering load. The first pressure sensor 4 feeds back a pressure signal. The control port LS1 of the priority valve 5 is blocked. The priority valve 5 is in the first working position under the control pressure at both ends and the spring force, so that the electric control part of the load-sensitive electric pump 2 is energized to output at maximum displacement. At this time, the load-sensitive electric pump 2 is in a load-sensitive control state. When the priority valve 5 is in the first working position, the hydraulic oil supplied by the outlet of the load-sensitive electronic pump 2 flows out through the steering port CF of the priority valve 5, flows into the inlet of the steering gear 6, flows out from one working port of the steering gear 6 to a certain chamber of the steering cylinder 7, and then flows back from another chamber of the steering cylinder 7 to another working port of the steering gear 6, and finally flows back to the hydraulic oil tank 1 through the return port of the steering gear 6. (If the hydraulic oil at the inlet of the steering gear 6 flows out from the first working port of the steering gear 6, it flows into the rodless chamber of the steering cylinder 7. The hydraulic oil in the rod chamber of the steering cylinder 7 flows out through the second working port of the steering gear 6 and finally flows back to the hydraulic oil tank 1 through the return port of the steering gear 6. If the hydraulic oil at the inlet of the steering gear 6 flows out from the second working port of the steering gear 6, it flows into the rod chamber of the steering cylinder 7. The hydraulic oil in the rodless chamber of the steering cylinder 7 flows out through the first working port of the steering gear 6 and finally flows back to the hydraulic oil tank 1 through the return port of the steering gear 6.) The output flow rate of the load-sensitive electronic pump 2 varies with the rotation speed of the steering gear 6. The faster the steering gear 6 rotates, the larger the valve core opening of the steering gear 6 becomes. In order to keep the pressure difference between the oil outlet of the load-sensitive electronic pump 2 and the load feedback port LS2 of the steering gear 6 constant, the oil outlet of the load-sensitive electronic pump 2 will output more flow. Conversely, the slower the steering gear 6 rotates, the smaller the valve core opening of the steering gear 6 becomes. In order to keep the pressure difference between the oil outlet of the load-sensitive electronic pump 2 and the load feedback port LS2 of the steering gear 6 constant, the load-sensitive electronic pump 2 will output less flow. There is no excess flow during the entire steering process, and there is no throttling energy loss.

[0017] As an improvement to this embodiment, the priority valve 5 further includes an overflow valve 5-1 connected to the control oil circuit. The oil inlet of the overflow valve 5-1 is connected to the control oil circuit of the priority valve 5, and the oil outlet of the overflow valve 5-1 is connected to the hydraulic oil tank 1 through the return oil port T1 of the priority valve 5. When the steering load of the steering gear 6 increases to a certain value, the overflow valve 5-1 in the priority valve 5 opens, and the priority valve 5 switches to the second working position. The hydraulic oil at the outlet of the load-sensitive electric pump 2 flows into the multi-way valve 9 through the working port EF of the priority valve 5. At the same time, the first pressure sensor 4 feeds back a pressure signal. After receiving the signal, the controller outputs a control signal to reduce the displacement of the load-sensitive electric pump 2 to the standby displacement and energize the reversing valve 3. The reversing valve 3 switches to the second working position. The control port LS1 of the priority valve 5 is connected to the load feedback port LS2 of the steering gear 6 through the reversing valve 3, and the steering load is connected through the inside of the steering gear 6. The outlet of the load-sensitive electric pump 2 is connected to the control port LS0 of the load-sensitive electric pump 2 through the reversing valve 3. The load-sensitive electric pump 2 is in the electronic control program control state, and the load-sensitive electric pump 2 outputs a small flow rate with small overflow loss.

[0018] 3. When operating independently: Steering gear 6 has no action signal, but the operating control outputs an action signal. Upon receiving this signal, the controller outputs a control signal, causing the load-sensitive electric pump 2 and electric pump 11 to output corresponding flow rates. This energizes the reversing valve 3, which switches to the second operating position. The oil outlet of the load-sensitive electric pump 2 is connected to its control port LS0. The control port LS1 of the priority valve 5 is connected to the load feedback port LS2 of the steering gear 6. Because the steering gear 6 is not operating, the load feedback port LS2 connects to the internal return oil of the steering gear 6. The first pressure sensor 4 receives no pressure signal feedback. At this time, the load-sensitive electric pump 2 is in an electronically controlled program state. The flow rate output by the load-sensitive electric pump 2 exits through the working port EF of the priority valve 5 and enters through the inlet port P2 of the multi-way valve 9. The flow rate output by the electric pump 11 enters through the inlet port P2 of the multi-way valve 9. The total output flow of load-sensitive electric pump 2 and electric pump 11 corresponds to the working control signal. The larger the working control signal, the larger the output flow of load-sensitive electric pump 2 and electric pump 11, but there is no excess flow output and no throttling energy loss.

[0019] When the working cylinder 8 moves to its limit position, causing the system pressure to rise to the set pressure, or when the working cylinder 8 is under a large load, causing the system pressure to rise to the set pressure, the second pressure sensor 10 transmits a signal to the controller. The controller outputs a control signal, causing the load-sensitive electric pump 2 and electric pump 11 to output the minimum flow rate, with no overflow energy loss.

[0020] 4. When steering and working simultaneously: Steering gear 6 outputs a steering action signal and working operation outputs an action signal. After receiving the signal, the controller outputs a control signal, causing the load-sensitive electric pump 2 and electric pump 11 to output corresponding flow rates. The total flow rate simultaneously meets the requirements of the steering and working systems, energizing the reversing valve 3. The reversing valve 3 switches to the second working position. The oil outlet of the load-sensitive electric pump 2 is connected to the control port LS0 of the load-sensitive electric pump 2. The control port LS1 of the priority valve 5 is connected to the load feedback port LS2 of the steering gear 6. The load feedback port LS2 of the steering gear 6 is connected to the steering load. The first pressure sensor 4 feeds back a pressure signal. At this time, the load-sensitive electric pump 2 is in the electronic control program control state. The control port LS1 of the priority valve 5 is connected to the load feedback port LS2 of the steering gear 6 through the reversing valve 3, controlling the position of the valve core of the priority valve 5. The priority valve 5 is in the position between the first working position and the second working position. The load-sensitive electronic pump 2 outputs according to the greater of the steering demand and the working demand, so that the output flow of the load-sensitive electronic pump 2 is discharged through the steering oil port CF of the priority valve 5 to meet the steering system demand. The remaining flow is discharged through the working oil port EF of the priority valve 5, and merges with the output flow of the electronic pump 11. Together they enter the oil inlet P2 of the multi-way valve 9 to meet the working system demand, without throttling energy loss.

[0021] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A positive flow hydraulic system based on a load-sensitive electronically controlled pump, comprising a steering cylinder (7), a steering gear (6) for controlling the movement of the steering cylinder (7), a working cylinder (8), and a multi-way valve (9) for controlling the movement of the working cylinder (8), wherein the first working port and the second working port of the steering gear (6) are respectively connected to the rod chamber and the rodless chamber of the steering cylinder (7), the first working port and the second working port of the multi-way valve (9) are respectively connected to the rod chamber and the rodless chamber of the working cylinder (8), and the return port of the steering gear (6) and the return port of the multi-way valve (9) are both connected to a hydraulic oil tank (1), characterized in that: It also includes a directional valve (3), a priority valve (5), and a load-sensitive electric pump (2) and an electric pump (11), both of which are connected to the hydraulic oil tank (1). The priority valve (5) includes a first working position, a second working position and a control oil circuit. The priority valve (5) is provided with a control port that communicates with the control oil circuit. The control oil circuit is used to switch the valve position of the priority valve (5) so that the priority valve (5) is in one of the following positions: alone in the first working position, alone in the second working position, and in a position between the first working position and the second working position. The oil inlet of the steering gear (6) is connected to the steering port of the priority valve (5), and the oil inlet of the steering gear (6) is in fluid communication with the load-sensitive electric pump (2) through the priority valve (5) in the first working position; the oil inlet of the multi-way valve (9) is connected to the working port of the priority valve (5), and the oil inlet of the multi-way valve (9) is in fluid communication with the load-sensitive electric pump (2) through the priority valve (5) in the second working position, and the oil inlet of the multi-way valve (9) is also in fluid communication with the electric pump (11); The reversing valve (3) includes a first working position and a second working position. When the reversing valve (3) is in the first working position, the load feedback port of the steering gear (6) is connected to the control port of the load-sensitive electric pump (2), and the control port of the priority valve (5) is blocked. The priority valve (5) is in the first working position. When the reversing valve (3) is in the second working position, the oil outlet of the load-sensitive electric pump (2) is connected to the control port of the load-sensitive electric pump (2), and the control port of the priority valve (5) is connected to the load feedback port of the steering gear (6). The working position of the priority valve (5) depends on the pressure difference between the steering oil port of the priority valve (5) and the steering gear (6). The steering gear (6) is provided with a first pressure sensor (4) at the load feedback port, and the electronically controlled pump (11) is provided with a second pressure sensor (10) at the oil outlet.

2. The positive flow hydraulic system based on a load-sensitive electronically controlled pump according to claim 1, characterized in that: The reversing valve (3) has a first control terminal and a second control terminal, wherein: When the second control terminal of the reversing valve (3) is energized, the reversing valve (3) is controlled to be in the second working position; When the second control terminal of the reversing valve (3) is de-energized, the reversing valve (3) is in the first working position under the control of the first control terminal.

3. The positive flow hydraulic system based on a load-sensitive electronically controlled pump according to claim 1, characterized in that: The priority valve (5) also includes a relief valve (5-1) connected to the control oil circuit. The oil inlet of the relief valve (5-1) is connected to the control oil circuit of the priority valve (5), and the oil outlet of the relief valve (5-1) is connected to the hydraulic oil tank (1).

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