A liquid-filled valve, hydraulic steering brake system and engineering vehicle

Abstract

This invention discloses a filling valve, a hydraulic steering and braking system, and an engineering vehicle. The filling valve includes a priority valve and a pilot unloading valve. The priority valve LS1 port is connected to the pilot unloading valve P port. A second check valve and a pressure holding device are sequentially arranged in the passage from the priority valve CF port to the filling valve A port. The pressure holding device is a valve that controls the unidirectional flow of hydraulic fluid. A pilot oil circuit is led out between the second check valve and the pressure holding device and connected to the pilot oil port of the pilot unloading valve. The hydraulic steering and braking system includes an accumulator, a steering gear, and the filling valve. The filling valve A port is connected to the accumulator, the priority valve CF port is connected to the steering gear P port, and the pilot unloading valve LS port is connected to the steering gear LS port. The engineering vehicle uses the hydraulic steering and braking system. The filling valve provided by this invention has a simple structure, low cost, and good pressure holding capacity; the hydraulic steering and braking system provided by this invention has a simple structure, high system integration, and low system pressure loss.

Description

Technical Field

[0001] This invention belongs to the field of vehicle driving and control technology, and relates to a filling valve, a hydraulic steering and braking system, and an engineering vehicle. Background Technology

[0002] A filling valve is a hydraulic valve used to store high-pressure oil supplied by the main pump in an accumulator. The high-pressure oil stored in the accumulator can be used to achieve functions such as driving and parking.

[0003] Figure 1 The diagram shows the principle of an existing filling valve. When oil enters the filling valve through port P, the spring in the first check valve 1 has a certain opening pressure. This opening pressure is greater than the set pressure of the spring in the two-position three-way hydraulic directional valve 5. The two-position three-way hydraulic directional valve 5 switches to the left valve position, and the oil flows to port A. Port A is connected to the accumulator 3. After the circuit is pressurized, it pushes the two-position two-way hydraulic directional valve 4 to the right valve position, and the pressure at port A continues to rise. When it exceeds the set pressure of the first sequence valve 2, the first sequence valve 2 opens, allowing the accumulator 3 to store pressure. This pressure is greater than the set pressure of the first check valve 1, which will push the two-position three-way hydraulic directional valve 5 to the right valve position, and the filling process ends. Port P and port T are connected. When the pressure at port A decreases due to braking, and falls below the set pressure of the spring in the two-position two-way hydraulic directional valve 4, the two-position two-way hydraulic directional valve 4 switches to the left valve position, the pressure at the accumulator 3 is relieved, and the two-position three-way hydraulic directional valve 5 switches to the left valve position, starting the filling process. Among them, the two-position two-way hydraulic control directional valve 4 is set to the filling start pressure, and the first sequence valve 2 is set to the filling stop pressure.

[0004] The technical problems of the existing filling valve are: (1) It needs to be composed of multiple valve components, which is complex and costly; (2) It has weak pressure holding capacity: the first sequence valve 2 and the two-position two-way hydraulic control directional valve 4 are spool valve structures. Although the accumulator 3 is used to hold the pressure, leakage is still likely to occur, resulting in frequent filling; in addition, there is no pressure holding measure for the A port connected to the accumulator 3.

[0005] On the other hand, engineering vehicles, such as all-terrain cranes and container reach stackers, generally use fully hydraulic steering and braking. For example... Figure 2 As shown, existing hydraulic steering and braking systems in the industry are generally of a series structure. During system operation, the main pump provides pressurized oil, which preferentially flows to the charging valve. The charging valve first charges the accumulator to supply the braking system. Once the pressure reaches the specified level, the valve position switches, and the oil then flows to the steering system. The braking and steering systems typically have their own flow distribution valves with similar functions. These valves generate throttling losses within the system, resulting in significant energy consumption and low integration of the hydraulic steering and braking system.

[0006] Therefore, it is necessary to propose a filling valve with simple structure, low cost and strong pressure holding capacity, and also to propose a hydraulic steering and braking system with simple structure, high integration and low pressure loss. Summary of the Invention

[0007] Objectives of the invention: The first objective of this invention is to provide a filling valve that is simple in structure, low in cost, and has a strong pressure-holding capacity; the second objective of this invention is to provide a hydraulic steering and braking system based on the filling valve that is simple in structure, highly integrated, and has low pressure loss. This hydraulic steering and braking system utilizes the filling valve and a load feedback loop to simultaneously provide high-pressure oil to both the braking and steering systems, resulting in higher system integration; the third objective of this invention is to provide an engineering vehicle that uses this hydraulic steering and braking system.

[0008] Technical solution: The filling valve of the present invention includes a priority valve and a pilot unloading valve. The LS port of the priority valve is connected to the P port of the pilot unloading valve. A second check valve and a pressure holding device are sequentially arranged in the passage from the CF port of the priority valve to the A port of the filling valve. The pressure holding device adopts a valve component that controls the unidirectional flow of oil. A pilot oil circuit is led out between the second check valve and the pressure holding device and connected to the pilot oil port of the pilot unloading valve.

[0009] Furthermore, the pressure-holding device employs a third check valve.

[0010] Furthermore, the filling valve is a dual-circuit filling valve with two A ports, namely A1 and A2; the pressure holding device consists of two parallel third check valves, which are connected to A1 and A2 ports respectively.

[0011] Furthermore, the pressure-holding device employs a second sequence valve.

[0012] Furthermore, a filling valve C port is provided between the second check valve and the second sequence valve to provide sufficient safety driving pressure when the pressure at port A drops sharply due to a malfunction.

[0013] Furthermore, the filling valve is a dual-circuit filling valve with two A ports, namely A1 and A2; the pressure holding device consists of two parallel second sequence valves, with the oil outlets of the two second sequence valves connected to A1 and A2 respectively.

[0014] The present invention discloses a hydraulic steering and braking system, comprising a braking system, a steering system, and the aforementioned filling valve, wherein the braking system includes an accumulator, and the steering system includes a steering gear; the A port of the filling valve is connected to the accumulator, the CF port of the priority valve is connected to the P port of the steering gear, and the LS port of the pilot unloading valve is connected to the LS port of the steering gear.

[0015] Another hydraulic steering and braking system according to the present invention includes a braking system, a steering system and the above-mentioned filling valve, wherein the braking system includes two accumulators, the steering system includes a steering gear; the filling valve A1 port and A2 port are respectively connected to the two accumulators, the priority valve CF port is connected to the steering gear P port; the pilot unloading valve LS port is connected to the steering gear LS port.

[0016] The engineering vehicle described in this invention utilizes the aforementioned hydraulic steering and braking system.

[0017] Furthermore, the engineering vehicles include cranes, container reach stackers, forklifts, and loaders.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0019] (1) The present invention utilizes a combination of a priority valve and a pilot unloading valve to realize the function of a filling valve, and sets a pressure holding device in the filling valve. The provided filling valve has a simple structure, low cost, and good pressure holding capacity.

[0020] (2) The hydraulic steering and braking system provided by the present invention shares the flow distribution function of the filling valve with the steering system and the braking system. The steering system and the braking system can work at the same time without affecting each other. The structure of the hydraulic steering and braking system is simplified, the system integration is high, and the system pressure loss is small. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an existing filling valve;

[0022] Figure 2 This is a schematic diagram of an existing hydraulic steering and braking system;

[0023] Figure 3 This is a schematic diagram of the filling valve in Embodiment 1 of this application;

[0024] Figure 4 This is a schematic diagram of the filling valve in Embodiment 2 of this application;

[0025] Figure 5 This is a schematic diagram of the filling valve in Embodiment 3 of this application;

[0026] Figure 6 This is a schematic diagram of the filling valve in Embodiment 4 of this application;

[0027] Figure 7 This is a schematic diagram of the hydraulic steering and braking system provided in the embodiments of this application. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] This application provides a filling valve, including a priority valve 6 and a pilot unloading valve 7. The load feedback port LS1 of the priority valve 6 is connected to the P port of the pilot unloading valve 7. A second check valve 8 and a pressure holding device are sequentially arranged in the passage from the priority working port CF of the priority valve 6 to the A port of the filling valve. The pressure holding device is a valve that controls the unidirectional flow of oil. A pilot oil circuit is led out between the second check valve 8 and the pressure holding device and connected to the pilot port of the pilot unloading valve 7. The A port of the filling valve is used to connect to the accumulator 3 to provide high-pressure oil to the braking system. The auxiliary working port EF of the priority valve 6 is connected to the B port of the priority valve 6.

[0030] Priority valve 6 is a flow distribution valve. Its working principle is as follows: when oil enters the inlet P, the left valve position throttles less than the right valve position and the spring set pressure, so it switches to the left valve position. Only when there is pressure at the load feedback port LS1 and the pressure at the left valve position is less than the pressure at the right valve position, the valve core switches to the priority working port CF.

[0031] The pilot unloading valve 7 works as follows: Under normal circumstances, the oil inlet and outlet are cut off. Only when the pilot oil port pressure reaches a certain value, or the inlet oil port pressure is greater than the spring set pressure, are the inlet and outlet connected. According to the valve position function, the pilot oil port pressure + the inlet oil port pressure should balance the spring force. During the pressure build-up process, the pilot oil port pressure continuously increases, while the inlet oil port pressure continuously decreases due to the conduction, eventually making the pilot oil port pressure equal to the spring force.

[0032] Example 1

[0033] like Figure 3 As shown, the pressure holding device uses a third check valve 9, which is connected to the second check valve 8 and the filling valve A port.

[0034] Example 2

[0035] like Figure 4 As shown, the pressure holding device uses a second sequence valve 10. The oil inlet of the second sequence valve 10 is connected to the second check valve 8, the oil outlet of the second sequence valve 10 is connected to the filling valve A port, and the oil outlet of the second sequence valve 10 is connected to the filling valve T port.

[0036] In addition, a filling valve C port is led out between the second one-way valve 8 and the second sequence valve 10.

[0037] In Embodiment 2, the third check valve 9 is replaced with the second sequence valve 10. Compared with the check valve, in Embodiment 2, when the pressure at port A drops sharply due to a fault, port C can still have sufficient safety pressure to drive other systems, such as parking.

[0038] The working principle of the sequence valve is as follows: Under normal circumstances, the oil inlet and outlet are cut off. Only when the oil inlet pressure reaches a certain value will the oil inlet and outlet be connected. In order to avoid oil trapping in the spring chamber, it is also equipped with an oil discharge port.

[0039] Example 3

[0040] like Figure 5 As shown, this third embodiment is an extension of the first embodiment. The filling valve is a dual-loop filling valve with two ports A1 and A2. The pressure holding device consists of two parallel third check valves 9, which are connected to ports A1 and A2 respectively.

[0041] Example 4

[0042] like Figure 6 As shown, this fourth embodiment is an extension of the second embodiment. The filling valve is a dual-circuit filling valve with two A ports, namely A1 and A2. The pressure holding device consists of two parallel second sequence valves 10, with the oil outlet of each of the two second sequence valves 10 connected to A1 and A2 ports respectively.

[0043] The working principle of the filling valves provided in Embodiments 1 to 4 of this application is as follows:

[0044] When hydraulic oil flows into the priority valve 6 from port P, the pilot port of the pilot unloading valve 7 is closed due to the lack of pressure or low pressure at port A. Port LS is also shut off, and the priority valve 6, under spring force, is in the right-side position, allowing hydraulic oil to flow from port P to port CF. A second check valve 8 is installed in the CF port passage to control the unidirectional flow of oil and maintain pressure effectively. A third check valve 9 or a second sequence valve 10 is connected to port A. Due to the function of the third check valve 9 or the second sequence valve 10, the accumulator 3 connected to port A has a strong pressure-holding capacity.

[0045] As the pressure from port CF to port A continues to rise, the pressure at the pilot port of pilot unloading valve 7 increases, eventually connecting the inlet and outlet of pilot unloading valve 7, and unloading port LS1 of priority valve 6. Because the oil flows through port LS1 of priority valve 6, the throttling loss on the left side of priority valve 6 is small, and ultimately the hydraulic pressure on the left side is greater than the sum of the pressure on the right side and the spring force, causing the valve position to switch to port EF, and hydraulic oil flows from port P to port B.

[0046] When the pressure at port A decreases, the pressure at the pilot port of the pilot unloading valve 7 decreases. When the pressure at the pilot port decreases to a certain value and is insufficient to overcome the spring force, the inlet and outlet of the pilot unloading valve 7 are shut off, and the filling process is repeated.

[0047] like Figure 7As shown, this application embodiment also provides a hydraulic steering braking system, including a braking system, a steering system and the filling valve described in embodiment three. The braking system includes a brake pedal valve 11, a brake cylinder 12 and two accumulators 3.

[0048] The steering system includes a steering gear 13 and a steering cylinder 14. The steering cylinder 14 includes a left steering cylinder and a right steering cylinder. The steering gear 13 has a working port L and a working port R. The working port L is connected to the rod chamber of the left steering cylinder and the rodless chamber of the right steering cylinder, respectively. The working port R is connected to the rodless chamber of the left steering cylinder and the rod chamber of the right steering cylinder, respectively.

[0049] The charging valves A1 and A2 are connected to the two accumulators 3 respectively. The priority working oil port CF of the priority valve 6 is connected to the P port of the steering gear 13, and the pilot unloading valve 7 is connected to the LS port of the steering gear 13. The high-pressure oil in the two accumulators 3 is supplied to the brake cylinder 12 via the brake pedal valve 11.

[0050] The working principle of the hydraulic steering and braking system provided in this application embodiment is as follows:

[0051] When the system is first started, there is no pressure at ports A1 and A2, the pilot unloading valve 7 is not open, and the LS circuit of the priority valve 6 is not connected. Under the action of the spring of the priority valve 6, the oil flows from port CF to the steering gear 13 and the accumulator 3.

[0052] If steering is not performed, the accumulator 3 will continue to fill with fluid until it reaches the set pressure of the pilot unloading valve 7, causing the pilot unloading valve 7 to open. This connects the LS1 port of the priority valve 6 with the LS port of the steering gear 13, and the priority valve 6 switches its position, allowing the fluid to flow to the EF port. At this point, the accumulator 3 is fully filled, and the steering gear 13 is connected to the LS1 port of the priority valve 6, allowing for normal steering. The accumulator 3, now full of fluid, provides high-pressure fluid for the service brakes, and the two processes do not interfere with each other. When the service brakes are applied, the brake pedal valve 11 is depressed, and the high-pressure fluid stored in the accumulator 3 enters the brake cylinder 12, thus achieving braking.

[0053] When turning, the steering gear 13 load feedback port LS establishes pressure, actuating the priority valve 6, causing the priority valve 6 to be in the CF port. The hydraulic oil from the P port flows to the steering gear 13 through the CF port. The steering gear 13 controls whether the hydraulic oil flows out from the L port or the R port through the steering wheel. If turning left, the hydraulic oil flows from the L port to the steering cylinder 14; if turning right, the hydraulic oil flows from the R port to the steering cylinder 14. At the same time, when the pressure of the accumulator 3 is lower than the steering pressure, oil can also be supplied to the accumulator 3 through the CF port, so that both can act simultaneously.

[0054] This application also provides an engineering vehicle that uses the hydraulic steering and braking system described in this application. The engineering vehicle can be, for example, a crane, a container reach stacker, a forklift, a loader, etc.

Claims

1. A hydraulic steering and braking system, characterized in that, The system includes a braking system, a steering system, and a filling valve. The filling valve includes a priority valve (6) and a pilot unloading valve (7). The LS1 port of the priority valve (6) is connected to the P port of the pilot unloading valve (7). A second check valve (8) and a pressure holding device are sequentially arranged on the passage from the CF port of the priority valve (6) to the A port of the filling valve. The pressure holding device is a valve that controls the unidirectional flow of oil. A pilot oil circuit is led out between the second check valve (8) and the pressure holding device and connected to the pilot oil port of the pilot unloading valve (7). The braking system includes a brake pedal valve (11), a brake cylinder (12), and an accumulator (3). The steering system includes a steering gear (13). The A port of the filling valve is connected to the accumulator (3), and the CF port of the priority valve (6) is connected to the P port of the steering gear (13). The LS port of the pilot unloading valve (7) is connected to the LS port of the steering gear (13). The high-pressure oil in the accumulator (3) is supplied to the brake cylinder (12) via the brake pedal valve (11).

2. The hydraulic steering and braking system according to claim 1, characterized in that, The pressure holding device uses a third check valve (9).

3. The hydraulic steering and braking system according to claim 2, characterized in that, The filling valve is a dual-circuit filling valve with two A ports, namely A1 and A2. The pressure holding device consists of two parallel third check valves (9), which are connected to A1 and A2 ports respectively.

4. The hydraulic steering and braking system according to claim 1, characterized in that, The pressure holding device uses a second sequence valve (10).

5. The hydraulic steering and braking system according to claim 4, characterized in that, A filling valve C port is led out between the second check valve (8) and the second sequence valve (10) to provide sufficient safety driving pressure when the pressure at port A drops sharply due to a malfunction.

6. The hydraulic steering and braking system according to claim 4, characterized in that, The filling valve is a dual-circuit filling valve with two A ports, namely A1 port and A2 port; the pressure holding device consists of two parallel second sequence valves (10), with the oil outlets of the two second sequence valves (10) respectively connected to A1 port and A2 port.

7. A hydraulic steering and braking system, characterized in that, The system includes a braking system, a steering system, and a filling valve. The filling valve includes a priority valve (6) and a pilot unloading valve (7). The LS1 port of the priority valve (6) is connected to the P port of the pilot unloading valve (7). A second check valve (8) and a pressure holding device are sequentially arranged on the passage from the CF port of the priority valve (6) to the A port of the filling valve. The pressure holding device is a valve that controls the unidirectional flow of oil. A pilot oil circuit is led out between the second check valve (8) and the pressure holding device and connected to the pilot oil port of the pilot unloading valve (7). The pressure holding device uses a third check valve (9) or a second sequence valve (10); when the pressure holding device uses a third check valve (9), the filling valve is a double-circuit filling valve with two A ports, the two A ports being A1 port and A2 port respectively; the pressure holding device consists of two third check valves (9) connected in parallel, the two third check valves (9) being connected to A1 port and A2 port respectively; when the pressure holding device uses a second sequence valve (10), the filling valve is a double-circuit filling valve with two A ports, the two A ports being A1 port and A2 port respectively; the pressure holding device consists of two second sequence valves (10) connected in parallel, the oil outlets of the two second sequence valves (10) being connected to A1 port and A2 port respectively; The braking system includes a brake pedal valve (11), a brake cylinder (12), and two accumulators (3). The steering system includes a steering gear (13). The filling valves A1 and A2 are connected to the two accumulators (3) respectively. The priority valve (6) CF port is connected to the steering gear (13) P port. The pilot unloading valve (7) LS port is connected to the steering gear (13) LS port. The high-pressure oil in the two accumulators (3) is supplied to the brake cylinder (12) via the brake pedal valve (11).

8. The hydraulic steering and braking system according to claim 7, characterized in that, A filling valve C port is led out between the second check valve (8) and the second sequence valve (10) to provide sufficient safety driving pressure when the pressure at port A drops sharply due to a malfunction.

9. An engineering vehicle, characterized in that, The engineering vehicle uses the hydraulic steering and braking system as described in claim 1 or 7.

10. The engineering vehicle according to claim 9, characterized in that, The engineering vehicles include cranes, container reach stackers, forklifts, and loaders.

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