A variable pump flow control hydraulic system

Abstract

The present invention provides a variable pump flow control hydraulic system, which includes a main oil circuit and a flow control system. The main oil circuit includes a small flow signal oil port and a large flow signal oil port, and the pressure of the large flow signal oil port is greater than that of the small flow signal oil port. The flow control system includes a shuttle valve, a pressure reducing valve, a hydraulic directional control valve, a variable hydraulic pump and a fuel tank. One input end of the shuttle valve is connected to the small flow signal oil port, the other input end of the shuttle valve is connected to the large flow signal oil port, the output end of the shuttle valve is connected to the input end of the pressure reducing valve, the output end of the pressure reducing valve is connected to the signal oil port of the hydraulic directional control valve, the input end of the hydraulic directional control valve is connected to the fuel tank, the output end of the hydraulic directional control valve is connected to the signal oil port of the variable hydraulic pump, the input end of the variable hydraulic pump is connected to the fuel tank, and the output end of the variable hydraulic pump is connected to the input oil port of the main oil circuit. The present invention meets the usage requirements with a large difference in required flow between different actions, and there will be no situation of excessive flow overflow and heat generation; the cost is relatively low.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic technology, and particularly to a variable pump flow control hydraulic system. Background Art

[0002] With the improvement of users' requirements for the operation efficiency of cranes, it is required that the oil pump can provide sufficient flow to meet the system requirements. However, when the flow required for a certain action of the crane is much larger than that required for other actions, in a fixed displacement pump system, small flow actions will overflow due to the remaining flow and generate a large amount of heat, which cannot meet the design and usage requirements. Although when using a load-sensing variable system, the output of the oil pump is only related to the opening of the multi-way valve required for that action, and there will be no excess flow overflowing and heating, which can solve the above problems. However, using a load-sensing variable system has problems of complex system control and high component costs.

[0003] For the telescopic actions of some telescopic cranes, the hydraulic flow required before and after the telescopic actions of the crane varies greatly. Therefore, it is necessary to design a hydraulic system with low cost and that meets the usage requirements with a large difference in the flow required between different actions. Summary of the Invention

[0004] The present invention provides a variable pump flow control hydraulic system. Using the structure of the present invention, it meets the usage requirements with a large difference in the flow required between different actions, and there will be no situation of excess flow overflowing and heating; the cost is relatively low.

[0005] To achieve the above object, the technical solution of the present invention is: a variable pump flow control hydraulic system, including a main oil circuit and a flow control system. The main oil circuit includes a small flow signal oil port, a large flow signal oil port, and a main oil circuit input oil port, and the pressure of the large flow signal oil port is greater than that of the small flow signal oil port.

[0006] The flow control system includes a shuttle valve, a pressure reducing valve, a hydraulic control directional valve, a variable hydraulic pump, and a fuel tank; one input end of the shuttle valve is connected to the small flow signal oil port, the other input end of the shuttle valve is connected to the large flow signal oil port, the output end of the shuttle valve is connected to the input end of the pressure reducing valve, the output end of the pressure reducing valve is connected to the signal oil port of the hydraulic control directional valve, the drain port of the hydraulic control directional valve is connected to the fuel tank, the output end of the hydraulic control directional valve is connected to the signal oil port of the variable hydraulic pump, the input end of the variable hydraulic pump is connected to the fuel tank, and the output end of the variable hydraulic pump is connected to the main oil circuit input oil port.

[0007] When the small flow signal oil port outputs hydraulic oil, the oil pressure of the small flow signal oil port is not sufficient to cause the hydraulic control directional valve to change direction; when the large flow signal oil port outputs hydraulic oil, the hydraulic oil of the large flow signal oil port is processed by the pressure reducing valve and then causes the hydraulic control directional valve to change direction.

[0008] With the above settings, when the small-flow signal oil port outputs hydraulic oil, the oil pressure at the small-flow signal oil port is not sufficient to cause the hydraulic directional control valve to change direction. At this time, the variable displacement hydraulic pump discharges the variable displacement hydraulic oil. When the large-flow signal oil port outputs hydraulic oil, the hydraulic oil at the large-flow signal oil port is processed by the pressure reducing valve, causing the hydraulic directional control valve to change direction. Then, the hydraulic oil passing through the hydraulic directional control valve is used as signal oil and sent to the variable displacement hydraulic pump. At this time, the variable displacement hydraulic pump outputs variable displacement hydraulic oil, thereby enabling the variable displacement hydraulic pump to automatically switch the flow rate of the hydraulic variable pump according to the required hydraulic flow rate of the main oil circuit of the hydraulic system load and send it to the input oil port of the main oil circuit. This not only meets the demand for large-flow operations in the main oil circuit but also prevents the system from overflowing and heating up during small-flow operations in the main oil circuit. Compared with using a load-sensing variable system, it reduces costs and simplifies the control of the hydraulic system.

[0009] Further, the hydraulic directional control valve is a two-position two-way hydraulic directional control valve.

[0010] Further, when the large-flow signal oil port outputs, the pressure at the output end of the pressure reducing valve is greater than the pressure required for the hydraulic directional control valve to change direction. With the above settings, after receiving the signal oil output by the pressure reducing valve, the hydraulic directional control valve changes direction according to the pressure of the signal oil and then outputs hydraulic oil to the variable displacement hydraulic pump, causing it to switch to a large displacement. When the telescopic movement does not occur, the hydraulic directional control valve will not receive the pressure that causes it to change direction. The hydraulic directional control valve resets under the action of its own spring, and the oil that controls the variable displacement of the hydraulic pump is discharged, and the oil pump changes to a small displacement.

[0011] Further, the variable displacement hydraulic pump is a single-direction variable displacement hydraulic pump.

[0012] Further, the power source of the variable displacement hydraulic pump is an electric motor.

[0013] Further, the oil drain port of the hydraulic directional control valve is connected to the oil tank. Description of the Drawings

[0014] Figure 1 It is a connection block diagram of the main oil circuit and the flow control system of the present invention.

[0015] Description of the Drawings: 1. Main oil circuit; 11. Large-flow signal oil port; 12. Small-flow signal oil port; 13. Main oil circuit input oil port; 2. Shuttle valve; 3. Pressure reducing valve; 4. Hydraulic directional control valve; 5. Variable displacement hydraulic pump. Detailed Embodiment

[0016] The present invention will be further described in detail below in conjunction with the drawings and the detailed embodiment.

[0017] As Figure 1As shown in the figure, a variable pump flow control hydraulic system includes a main oil circuit 1 for controlling a telescopic hydraulic cylinder and a flow control system. The main oil circuit 1 includes a small flow signal oil port 12, a large flow signal oil port 11, and a main oil circuit 1 input oil port. The pressure of the large flow signal oil port 11 is greater than that of the small flow signal oil port 12.

[0018] The flow control system includes a shuttle valve 2, a pressure reducing valve 3, a hydraulic pilot-operated directional valve 4, a variable hydraulic pump 5, and a fuel tank; one input end of the shuttle valve 2 is connected to the small flow signal oil port 12, the other input end of the shuttle valve 2 is connected to the large flow signal oil port 11, the output end of the shuttle valve 2 is connected to the input end of the pressure reducing valve 3, the output end of the pressure reducing valve 3 is connected to the signal oil port of the hydraulic pilot-operated directional valve 4, the input end of the hydraulic pilot-operated directional valve 4 is connected to the fuel tank, the output end of the hydraulic pilot-operated directional valve 4 is connected to the signal oil port of the variable hydraulic pump, the input end of the variable hydraulic pump is connected to the fuel tank, and the output end of the variable hydraulic pump is connected to the main oil circuit input oil port 13.

[0019] When the telescopic hydraulic cylinder performs telescopic actions, the large flow signal oil port 11 outputs signal oil into the shuttle valve 2; when the telescopic hydraulic cylinder does not perform telescopic actions, the small flow signal oil port 12 outputs signal oil into the shuttle valve 2; when the small flow signal oil port 12 outputs hydraulic oil, the oil pressure of the small flow signal oil port 12 is not sufficient to cause the hydraulic pilot-operated directional valve 4 to change direction; when the large flow signal oil port 11 outputs hydraulic oil, the hydraulic oil of the large flow signal oil port 11 is processed by the pressure reducing valve 3, causing the hydraulic pilot-operated directional valve 4 to change direction; the hydraulic flow during the telescopic actions of the crane is about 3 times that of other actions. Whether telescopic actions are performed is judged by the shuttle valve 2, and thus signal oil is output through the shuttle valve 2.

[0020] With the above settings, when the small flow signal oil port 12 outputs hydraulic oil, the oil pressure of the small flow signal oil port 12 is not sufficient to cause the hydraulic pilot-operated directional valve 4 to change direction. At this time, the variable hydraulic pump 5 discharges the variable displacement hydraulic oil; when the large flow signal oil port 11 outputs hydraulic oil, the hydraulic oil of the large flow signal oil port 11 is processed by the pressure reducing valve 3, causing the hydraulic pilot-operated directional valve 4 to change direction. Then, the hydraulic oil passing through the hydraulic pilot-operated directional valve 4 is sent to the variable hydraulic pump 5 as signal oil. At this time, the variable hydraulic pump 5 outputs variable displacement hydraulic oil, so as to realize that the variable hydraulic pump 5 automatically switches the flow rate of the hydraulic variable pump according to the required hydraulic flow rate of the main oil circuit 1 of the hydraulic system load and sends it to the main oil circuit input oil port 13. This not only meets the requirements of the main oil circuit 1 for large flow actions but also prevents the system from overflowing and heating up when the main oil circuit 1 performs small flow actions. Compared with using a load-sensing variable system, it reduces costs and simplifies the control of the hydraulic system.

[0021] The hydraulic pilot-operated directional valve 4 is a two-position two-way hydraulic pilot-operated directional valve 4.

[0022] When the large-flow signal oil port 11 outputs, the pressure at the output end of the pressure reducing valve 3 is greater than the pressure required for the hydraulic directional control valve 4 to change its direction; among them, the pressure set by the pressure reducing valve 3 is 35 bar, and the direction-changing pressure of the hydraulic directional control valve 4 is 14 bar; after receiving the signal oil output by the pressure reducing valve 3, the hydraulic directional control valve 4 changes its direction according to the pressure of the signal oil, and then outputs hydraulic oil to the variable hydraulic pump 5 to make it change to a large displacement; when the telescopic movement does not act, the hydraulic directional control valve 4 will not receive the pressure that makes it change its direction, and the hydraulic directional control valve 4 resets under the action of its own spring, and the oil that controls the variable displacement of the variable hydraulic pump 5 is drained, and the oil pump changes to a small displacement; this valve is equivalent to a switching valve that controls whether the variable hydraulic pump 5 varies its displacement.

[0023] The variable hydraulic pump 5 is a unidirectional variable hydraulic pump 5.

[0024] The power source of the variable hydraulic pump 5 is an electric motor.

[0025] The oil drain port of the hydraulic directional control valve 4 is connected to the fuel tank.

Claims

1. A variable pump flow control hydraulic system, comprising a main oil circuit and a flow control system, characterized in that: The main oil circuit includes a small-flow signal oil port, a large-flow signal oil port, and a main oil circuit input oil port. The pressure of the large-flow signal oil port is greater than that of the small-flow signal oil port. The flow control system includes a shuttle valve, a pressure reducing valve, a hydraulic directional control valve, a variable displacement hydraulic pump, and a fuel tank. One input end of the shuttle valve is connected to the small-flow signal oil port, the other input end of the shuttle valve is connected to the large-flow signal oil port, the output end of the shuttle valve is connected to the input end of the pressure reducing valve, the output end of the pressure reducing valve is connected to the signal oil port of the hydraulic directional control valve, the drain port of the hydraulic directional control valve is connected to the fuel tank, the output end of the hydraulic directional control valve is connected to the signal oil port of the variable displacement hydraulic pump, the input end of the variable displacement hydraulic pump is connected to the fuel tank, and the output end of the variable displacement hydraulic pump is connected to the main oil circuit input oil port. When the small-flow signal oil port outputs hydraulic oil, the oil pressure of the small-flow signal oil port is not sufficient to cause the hydraulic directional control valve to change direction. The hydraulic directional control valve resets under the action of its own spring, and the oil for controlling the variable displacement of the variable displacement hydraulic pump is drained, and the oil pump changes to a small displacement. When the large-flow signal oil port outputs hydraulic oil, the hydraulic oil of the large-flow signal oil port is processed by the pressure reducing valve. After the hydraulic directional control valve receives the signal oil output by the pressure reducing valve, the pressure at the output end of the pressure reducing valve is greater than the pressure required for the hydraulic directional control valve to change direction. It changes direction according to the pressure of the signal oil, and then outputs hydraulic oil to the variable displacement hydraulic pump to change it to a large displacement. At this time, the variable displacement hydraulic pump outputs hydraulic oil with variable displacement, so as to realize that the variable displacement hydraulic pump automatically switches the flow rate of the hydraulic variable pump according to the required hydraulic flow rate of the main oil circuit of the hydraulic system and conveys it to the main oil circuit input oil port.

2. A variable pump flow control hydraulic system according to claim 1, characterized in that: The hydraulic directional control valve is a two-position two-way hydraulic directional control valve.

3. A variable pump flow control hydraulic system according to claim 1, characterized in that: The variable displacement hydraulic pump is a single-direction variable displacement hydraulic pump.

4. A variable pump flow control hydraulic system according to claim 1, wherein: The power source of the variable displacement hydraulic pump is an electric motor.

5. A variable pump flow control hydraulic system according to claim 1, characterized in that: The drain port of the hydraulic directional control valve is connected to the fuel tank.

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