A hydraulic system that realizes the function of high and low pressure unloading

Abstract

The present application provides a hydraulic system for realizing high and low pressure unloading functions, including: an oil tank, a steering gear, a priority type transfer control valve, a left steering cylinder, a right steering cylinder, a control valve, and an unloading valve. The P port of the steering gear and the P port of the priority type transfer control valve are both connected to the oil outlet pipeline of the oil tank; the steering gear is connected to the priority type transfer control valve. The EF port of the priority type transfer control valve is connected to the P port of the unloading valve, the P port of the unloading valve is communicated with the P' port, and the P' port is confluent into the working hydraulic system. A first elastic valve is provided between the P port and the T port of the unloading valve. A second elastic valve is provided between the P' port of the unloading valve and the first elastic valve for opening the first elastic valve to realize high pressure unloading. The MP' port of the unloading valve is connected to the P1 port and the P4 port of the control valve, and the P4 of the control valve is connected to the PLS of the unloading valve for controlling the on-off of the first elastic valve to realize low pressure unloading. High and low pressure unloading can be performed to reduce the temperature rise of the hydraulic oil, reduce the load of the steering system, and reduce the energy loss of the loader.

Description

Technical Field

[0001] The present invention belongs to the field of loader hydraulic control, and particularly relates to a hydraulic system for realizing high and low pressure unloading functions. Background Art

[0002] As a widely used construction machinery, loaders have different uses and complex working conditions, which determine the complexity of the operation of their hydraulic systems. Currently, the common loader hydraulic systems mainly include split systems and double-pump confluence systems.

[0003] The double-pump confluence system refers to using the hydraulic pressure of the steering system and the working hydraulic system to drive the working mechanism simultaneously. The working mechanism includes a bucket, a support arm, etc. When the working mechanism is under heavy load and needs to be lifted or lowered slowly, the working hydraulic system is in a high-pressure and small-flow working state, and the hydraulic oil flowing from the steering system into the working hydraulic system is also redundant. If the hydraulic oil of the steering system continues to be input into the working hydraulic system, it will cause a relatively high temperature rise of the hydraulic oil, increase the burden on the cooling system, and increase the energy loss of the whole machine equipment. Summary of the Invention

[0004] To solve the deficiencies of the prior art, the present invention provides a hydraulic system for realizing high and low pressure unloading functions, which can relieve the pressure of the hydraulic oil provided by the steering system when the working hydraulic system is in a high-pressure and low-pressure state, so as to reduce the temperature rise of the hydraulic oil, reduce the load of the steering system, and reduce the energy loss of the loader.

[0005] To achieve the purpose of the present invention, the following scheme is proposed:

[0006] A hydraulic system for realizing high and low pressure unloading functions includes: an oil tank, a steering gear, a priority type steering control valve, a left steering cylinder, a right steering cylinder, a control valve, and a unloading valve.

[0007] The P port of the steering gear and the P port of the priority type steering control valve are both connected to the oil outlet pipeline of the oil tank; the steering gear is connected to the priority type steering control valve for controlling the left steering cylinder and the right steering cylinder.

[0008] The EF port of the priority type steering control valve is connected to the P port of the unloading valve, and the P port of the unloading valve is communicated with the P' port, and the P' is confluent into the working hydraulic system.

[0009] A first elastic valve is provided between the P port and the T port of the unloading valve for controlling the on-off between the P port and the T port of the unloading valve.

[0010] A second elastic valve is provided between the P' port of the unloading valve and the first elastic valve. When the pressure of the working hydraulic system rises to a predetermined pressure, the second elastic valve opens, and the hydraulic oil discharged from the second elastic valve opens the first elastic valve to realize high-pressure unloading.

[0011] The MP' port of the unloading valve is connected to the P1 port and P4 port of the control valve. The P1 port of the control valve is used to push the spool of the control valve to move. The P4 port of the control valve is connected to the PLS of the unloading valve and is used to control the on-off of the first elastic valve. The first elastic valve is opened through the P4 port of the control valve to achieve low-pressure unloading.

[0012] Furthermore, the priority type transfer control valve has an A port and a B port, which are used to supply oil to the left steering cylinder and the right steering cylinder. The A port of the priority type transfer control valve is connected to the rodless cavity of the left steering cylinder and the rodless cavity of the right steering cylinder. The B port of the priority type transfer control valve is connected to the rodless cavity of the left steering cylinder and the rod cavity of the right steering cylinder.

[0013] Furthermore, the control valve also has a P2 port and a P3 port. After the hydraulic oil passing through the P1 port of the control valve pushes the controller spool to move to a predetermined position, the P2 port of the control valve is communicated with the P5 port, and the hydraulic oil of the unloading valve spool flows back to the fuel tank through the P5 port of the control valve. At the same time, the P3 port is connected to the P4 port, and the P3 port is a sealing structure. At this time, the oil passing through the Mp' port of the unloading valve is blocked.

[0014] The spool of the control valve is reset by a spring. When the spool of the control valve is in the reset state, the P2 port of the control valve is connected to the P4 port, the P3 port is disconnected from the P5 port, and the hydraulic oil input from the MP' port of the unloading valve to the P4 port of the control valve will be output from the P2 port of the control valve and push the first elastic valve through the PLS port of the unloading valve, so that the P port and the T port of the unloading valve are communicated to achieve low-pressure unloading during high-speed driving.

[0015] Furthermore, the T port of the unloading valve is communicated with the return oil pipe of the fuel tank; the Ls port of the steering gear is connected to the Ls port of the priority type transfer control valve and is connected to the return oil pipe of the fuel tank through the T1 port of the priority type transfer control valve; the T port of the priority type transfer control valve is connected to the fuel tank through the return oil pipe; the T port of the steering gear is connected to the return oil pipe of the fuel tank.

[0016] Furthermore, it also includes an oil suction filter, a liquid level gauge, an air filter, a return oil filter and a gear pump. The oil suction filter is arranged at the inlet of the oil outlet pipe of the fuel tank and is located inside the fuel tank. The liquid level gauge and the air filter penetrate through the outer wall of the fuel tank. The return oil filter is arranged on the return oil pipe of the fuel tank. The gear pump is arranged on the oil outlet pipe of the fuel tank and is located between the fuel tank and the steering gear.

[0017] The beneficial effects of the present invention are as follows: The first elastic valve is controlled to open by the second elastic valve, so that the hydraulic oil input from the priority type transfer control valve to the unloading valve in the steering system is directly discharged back to the fuel tank from the T port of the unloading valve to achieve high-pressure unloading. This working state is suitable for use when the working hydraulic system operates at high pressure; the P4 port and P2 port of the control valve are connected to the PLS of the unloading valve to open the first elastic valve, thereby achieving low-pressure unloading. This working state is suitable for use when the working hydraulic system operates at low pressure and when the transfer machine is driving. Description of the Drawings

[0018] The accompanying drawings described herein are only for illustrating selected embodiments and not all possible implementation schemes, let alone intended to limit the scope of the present invention.

[0019] Figure 1 A schematic diagram of the hydraulic system of the present application is shown.

[0020] Figure 2 A schematic diagram of the structure and connection of the unloading valve and the control valve is shown.

[0021] Figure 3 A schematic diagram of the state of the control valve during low-pressure unloading is shown.

[0022] Figure 4 A schematic diagram of the state of the control valve during contact with low-pressure unloading is shown.

[0023] Markings in the figure: oil tank - 1, suction filter - 2, liquid level gauge - 3, air filter - 4, return oil filter - 5, gear pump - 6, steering gear - 7, priority type steering control valve - 8, left steering cylinder - 9, right steering cylinder - 10, control valve - 11, unloading valve - 12, first elastic valve - 121, second elastic valve - 122. Specific Embodiments

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following describes the embodiments of the present invention in detail with reference to the accompanying drawings. However, the embodiments described herein are only part of the embodiments of the present invention, rather than all of the embodiments.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description. The terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. The terms "parallel", "perpendicular", etc. do not mean that the components are required to be absolutely parallel or perpendicular, but can be slightly inclined.

[0027] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Embodiment 1

[0029] As Figure 1 、 Figure 2 shown, a hydraulic system for realizing the high and low pressure unloading function includes: a fuel tank 1, a steering gear 7, a priority type flow control valve 8, a left steering cylinder 9, a right steering cylinder 10, a control valve 11, and a relief valve 12.

[0030] As Figure 1 shown, the P ports of the steering gear 7 and the priority type flow control valve 8 are both connected to the oil outlet pipeline of the fuel tank 1. The steering gear 7 is connected to the priority type flow control valve 8. Specifically, the R port of the steering gear 7 is connected to the b port of the priority type flow control valve 8, and the L port of the steering gear 7 is connected to the a port of the priority type flow control valve 8, for controlling the left steering cylinder 9 and the right steering cylinder 10.

[0031] As Figure 2 shown, the EF port of the priority type flow control valve 8 is connected to the P port of the relief valve 12. Part of the hydraulic oil of the priority type flow control valve 8 is input into the relief valve 12 through the EF port of the priority type flow control valve 8, and is confluent into the working hydraulic system through the P' port of the relief valve 12. The P port and the P' port of the relief valve 12 are in communication, and P' is confluent into the working hydraulic system.

[0032] As Figure 2 shown, a first elastic valve 121 is provided between the P port and the T port of the relief valve 12, for controlling the on-off between the P port and the T port of the relief valve 12. When the first elastic valve 121 is opened, the P port and the T port of the relief valve 12 can be connected. The hydraulic oil discharged from the EF port of the priority type flow control valve 8 returns to the fuel tank 1 through the T port of the relief valve 12 for unloading.

[0033] As Figure 2 shown, a second elastic valve 122 is provided between the P' port of the relief valve 12 and the first elastic valve 121. The opening pressure of the second elastic valve 122 is greater than the opening pressure of the first elastic valve 121. When the pressure of the working hydraulic system rises to a predetermined pressure, at this time, the hydraulic oil pressure at the P' port of the relief valve 12 is the same as the predetermined pressure, the second elastic valve 122 is opened, and the hydraulic oil discharged from the second elastic valve 122 opens the first elastic valve 121, so that the P port and the T port of the relief valve 12 are connected, and flows back to the fuel tank 1 through the T port to achieve high pressure unloading.

[0034] When the working system is in a high-pressure state, it requires a relatively large oil pressure, but a relatively small amount of oil. At this time, most of the hydraulic oil provided by the steering system is not needed. Since the P' port of the unloading valve 12 is connected in parallel with the working hydraulic system, the hydraulic pressure at the P' port of the unloading valve 12 is also in a high-pressure state equal to that of the working hydraulic system. To prevent the high-pressure hydraulic oil in the working hydraulic system from flowing back to the P port of the unloading valve 12, a one-way valve is provided between the P port and the P' port. When the pressure at the P' port exceeds the set value, the second elastic valve 122 will open, and the first elastic valve 121 will be controlled to open through the second elastic valve 122, so that the hydraulic oil input from the steering system through the priority type transfer control valve 8 into the unloading valve 12 is directly discharged back to the fuel tank from the T port of the unloading valve 12, realizing high-pressure unloading. That is, when the working hydraulic system is in a high-pressure state, the unloading state of the unloading valve 12 is called high-pressure unloading. This reduces the amount of hydraulic oil input from the steering system, that is, the priority type transfer control valve 8, into the working hydraulic system, thereby reducing the temperature rise of the hydraulic oil and the mechanical energy loss required for the hydraulic oil to be combined and enter the working hydraulic system.

[0035] In this embodiment, the high-pressure unloading pressure is set to 210 bar, and the opening pressure of the first elastic valve 121 is set to be less than or equal to 3.2 bar. When the pressure at the P' port of the unloading valve 12 reaches 210 bar, the second pressure valve 122 will open, and the pressure input to the first pressure valve 121 through the second pressure valve 122 will surely be greater than 3.2 bar. Therefore, the first pressure valve 121 will be opened, so that the hydraulic oil input from the steering system through the priority type transfer control valve 8 into the unloading valve 12 is directly discharged back to the fuel tank from the T port of the unloading valve 12, realizing high-pressure unloading.

[0036] The MP' port of the unloading valve 12 is connected to the P1 port and P4 port of the control valve 11. The P1 port of the control valve 11 is used to push the spool of the control valve 11 to move, and the P4 port of the control valve 11 is connected to the PLS of the unloading valve 12, which is used to control the on-off of the first elastic valve 121. By opening the first elastic valve 121 through the P4 port of the control valve 11, the P port and T port of the unloading valve 12 are connected, and the oil flows back to the fuel tank 1 through the T port, realizing low-pressure unloading.

[0037] In this embodiment, when the working hydraulic system is not working and the loader is in a high-speed transportation state, the neutral pressure of the multi-way valve is lower than 7 kg and greater than 3.2 bar, and the opening pressure of the first elastic valve 121 is less than or equal to 3.2 bar. The control valve 11 is in the state as shown in Figure 3 As shown, the oil in the working hydraulic system passes through the P' port and Mp' port of the unloading valve 12, then through the P4 port of the control valve 11, and finally through the P2 port of the control valve 11 to push the first elastic valve 121 of the unloading valve 12 to open, and the excess flow from the EF port of the priority type transfer control valve 8 is discharged back to the fuel tank 1 from the T port of the unloading valve 12, realizing low-pressure unloading during high-speed driving.

[0038] Preferably, as Figure 1 shown, the steering gear 7, the priority steering control valve 8, the control valve 11 and the unloading valve 12 are all provided with a T port connected to the return oil pipe of the fuel tank 1.

[0039] Specifically, the T port of the unloading valve 12 is communicated with the return oil pipe of the fuel tank 1; the Ls port of the steering gear 7 is connected to the Ls port of the priority steering control valve 8 and is connected to the return oil pipe of the fuel tank 1 through the T1 port of the priority steering control valve 8; the T port of the priority steering control valve 8 is connected to the fuel tank 1 through the return oil pipe; the T port of the steering gear 7 is connected to the return oil pipe of the fuel tank 1.

[0040] Specifically, as Figure 1 shown, the priority steering control valve 8 has an A port and a B port for supplying oil to the left steering cylinder 9 and the right steering cylinder 10.

[0041] More specifically, the A port of the priority steering control valve 8 is connected to the rod chamber of the left steering cylinder 9 and the rodless chamber of the right steering cylinder 10. The B port of the priority steering control valve 8 is connected to the rodless chamber of the left steering cylinder 9 and the rod chamber of the right steering cylinder 10. The rod chamber is the chamber on the side where the piston of the hydraulic cylinder is connected to the hydraulic rod; the rodless chamber is the chamber on the side where the piston and the inside of the hydraulic cylinder do not have a hydraulic rod. The pressure of the rod chamber and the rodless chamber on both sides of the piston is balanced by the hydraulic oil to push the piston and the hydraulic rod to move.

[0042] Embodiment 2

[0043] As Figure 1 shown, a hydraulic system for realizing the high and low pressure unloading function includes a fuel tank 1, an oil suction filter 2, a liquid level gauge 3, an air filter 4, a return oil filter 5, a gear pump 6, a steering gear 7, a priority steering control valve 8, a left steering cylinder 9, a right steering cylinder 10, a control valve 11 and an unloading valve 12. The oil suction filter 2 is arranged at the inlet of the outlet pipe of the fuel tank 1 and is located inside the fuel tank 1. The liquid level gauge 3 and the air filter 4 penetrate through the outer wall of the fuel tank 1. The return oil filter 5 is arranged on the return oil pipe of the fuel tank 1. The gear pump 6 is arranged on the outlet pipe of the fuel tank 1 and is located between the fuel tank 1 and the steering gear 7.

[0044] Embodiment 3

[0045] As Figure 3 shown, the control valve 11 also has a P2 port and a P3 port.

[0046] As Figure 4As shown, after the hydraulic oil passing through the 11P1 port of the control valve pushes the control valve spool to move to a predetermined position, the P2 port and the P5 port of the control valve 11 are communicated, and the hydraulic oil of the spool of the unloading valve 12 flows back to the fuel tank 1 through the P5 port of the control valve 11; at the same time, the P3 port is connected to the P4 port, and the P3 port is a sealing structure. At this time, the oil passing through the Mp' port of the unloading valve 12 is blocked, and the P4 port of the control valve 11 cannot inject the hydraulic oil into the first elastic valve 121 through the PLS of the unloading valve 12, so that the low-pressure unloading function fails. At this time, it can be switched to the high-pressure unloading state.

[0047] The spool of the control valve 11 is reset by a spring. As Figure 3 shown, when the spool of the control valve 11 is in the reset state, the P2 port and the P4 port of the control valve 11 are connected, the P3 port and the P5 port are disconnected, and the hydraulic oil input from the MP' port of the unloading valve 12 to the P4 port of the control valve 11 will be output from the P2 port of the control valve 11 and push the first elastic valve 121 through the PLS port of the unloading valve 12, so that the P port and the T port of the unloading valve 12 are communicated to achieve low-pressure unloading during high-speed driving.

[0048] The above are only the preferred embodiments of the present invention and do not represent the only or limit the present invention. Those skilled in the art should understand that various changes or equivalent replacements made to the present invention without departing from the scope of the present invention all belong to the scope of protection of the present invention.

Claims

1. A hydraulic system that realizes the functions of high and low pressure unloading, characterized in that, Including: Fuel tank (1), steering gear (7), priority type steering control valve (8), left steering cylinder (9), right steering cylinder (10), control valve (11), and unloading valve (12); The P port of the steering gear (7) and the P port of the priority type steering control valve (8) are both connected to the oil outlet pipeline of the fuel tank (1); the steering gear (7) is connected to the priority type steering control valve (8) for controlling the left steering cylinder (9) and the right steering cylinder (10); The EF port of the priority type steering control valve (8) is connected to the P port of the unloading valve (12), the P port of the unloading valve (12) is communicated with the P' port, and the P' port is merged into the working hydraulic system; A first elastic valve (121) is provided between the P port and the T port of the unloading valve (12) for controlling the on-off between the P port and the T port of the unloading valve (12); A second elastic valve (122) is provided between the P' port of the unloading valve (12) and the first elastic valve (121). When the pressure of the working hydraulic system rises to a predetermined pressure, the second elastic valve (122) opens, and the hydraulic oil discharged from the second elastic valve (122) opens the first elastic valve (121) to achieve high-pressure unloading; The MP' port of the unloading valve (12) is connected to the P1 port and the P4 port of the control valve (11). The P1 port of the control valve (11) is used to push the spool of the control valve (11) to move. The P4 of the control valve (11) is connected to the PLS of the unloading valve (12) for controlling the on-off of the first elastic valve (121). The first elastic valve (121) is opened through the P4 of the control valve (11) to achieve low-pressure unloading; The priority type steering control valve (8) has an A port and a B port for supplying oil to the left steering cylinder (9) and the right steering cylinder (10); the A port of the priority type steering control valve (8) is connected to the rodless cavity of the left steering cylinder (9) and the rodless cavity of the right steering cylinder (10); the B port of the priority type steering control valve (8) is connected to the rodless cavity of the left steering cylinder (9) and the rod cavity of the right steering cylinder (10); The control valve (11) also has a P2 port and a P3 port. After the hydraulic oil passing through the P1 port of the control valve (11) pushes the controller spool to move to a predetermined position, the P2 port of the control valve (11) is communicated with the P5 port, and the hydraulic oil of the spool of the unloading valve (12) flows back to the fuel tank (1) through the P5 port of the control valve (11); meanwhile, the P3 port is connected to the P4 port, and the P3 port is a plugging structure. At this time, the oil passing through the Mp' port of the unloading valve (12) is blocked; The spool of the control valve (11) is reset by a spring. When the spool of the control valve (11) is in the reset state, the P2 port of the control valve (11) is connected to the P4 port, the P3 port is disconnected from the P5 port, and the hydraulic oil input from the MP' port of the unloading valve (12) to the P4 port of the control valve (11) will be output from the P2 port of the control valve (11) and push the first elastic valve (121) through the PLS port of the unloading valve (12), so that the P port and the T port of the unloading valve (12) are communicated to achieve low-pressure unloading during high-speed driving.

2. The hydraulic system for realizing the high and low pressure unloading function according to claim 1, characterized in that, The T port of the unloading valve (12) is communicated with the return oil pipe of the oil tank (1); the Ls port of the steering gear (7) is connected to the Ls port of the priority type steering control valve (8), and is connected to the return oil pipe of the oil tank (1) through the T1 port of the priority type steering control valve (8); the T port of the priority type steering control valve (8) is connected to the oil tank (1) through the return oil pipe; the T port of the steering gear (7) is connected to the return oil pipe of the oil tank (1).

3. The hydraulic system for realizing high and low pressure unloading functions according to claim 1, characterized in that, It further includes an oil suction filter (2), a liquid level gauge (3), an air filter (4), a return oil filter (5) and a gear pump (6). The oil suction filter (2) is arranged at the inlet of the oil outlet pipe of the oil tank (1) and is located inside the oil tank (1). The liquid level gauge (3) and the air filter (4) penetrate through the outer wall of the oil tank (1). The return oil filter (5) is arranged on the return oil pipe of the oil tank (1). The gear pump (6) is arranged on the oil outlet pipe of the oil tank (1) and is located between the oil tank (1) and the steering gear (7).

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