Steering flow control valve, hydraulic steering system and wheeled mobile equipment

Abstract

The present invention relates to a hydraulic steering system. To solve the problem that the main spool in the existing steering flow control valve instantaneously reverses under the action of high-pressure oil, the present invention constructs a steering flow control valve, a hydraulic steering system, and a wheeled mobile device. In the steering flow control valve, the left pilot oil port is connected to the left hydraulic control end of the valve stem of the main valve through the left-position oil circuit of the left selector valve and the right-position oil circuit of the right selector valve; the right pilot oil port is connected to the left hydraulic control end of the valve stem of the main valve through the left-position oil circuit of the right selector valve and the right-position oil circuit of the left selector valve. When the main valve is in the left position, the right hydraulic control end of its valve stem is communicated with the left working oil port of the main valve through the left-position oil circuit of the left selector valve and a check valve; when the main valve is in the right position, the left hydraulic control end of its valve stem is communicated with the right working oil port of the main valve through the left-position oil circuit of the right selector valve and a check valve. In the present invention, the problem that the corresponding right selector valve or left selector valve closes with a delay when the left pilot oil port or the right pilot oil port admits pilot oil is solved.

Description

Technical Field

[0001] The present invention relates to a hydraulic steering system, and more particularly to a steering flow control valve, a hydraulic steering system and a wheeled mobile equipment. Background Art

[0002] The steering system of construction machinery such as loaders uses hydraulic power steering. Its hydraulic system includes a steering gear, a steering control valve, a steering cylinder, a pressure oil source, etc. The pressure oil source is usually a variable pump, and there is a greater demand for providing flow. The steering gear controls the steering control valve, and the steering control valve controls the steering cylinder.

[0003] Chinese Patent Document CN 104192201A discloses a hydraulic steering control valve and a hydraulic steering system. In the disclosed hydraulic steering control valve, it includes a main valve, a pilot left oil port and a pilot right oil port. The main valve has a main spool, a working oil inlet, a tank return oil port, and a working left oil port and a working right oil port for connecting with the steering cylinder, and a selection valve. The selection valve is connected between the main valve and the pilot left oil port and the pilot right oil port, so that the pilot left oil port communicates with the hydraulic control left end of the main spool to make the main spool work in the left position, or the pilot right oil port communicates with the hydraulic control right end of the main spool to make the main spool work in the right position. When the main spool works in the left position, the hydraulic control right end of the main spool communicates with the working left oil port, and when the main spool works in the right position, the hydraulic control left end of the main spool communicates with the working right oil port.

[0004] In the above steering control valve, the selection valve adopts a linkage double spool design. When the pilot left oil port or the pilot right oil port admits oil, the closing of one spool on one side of the selection valve is likely to cause delay, so that the main spool instantaneously commutes to the maximum position under the action of high-pressure oil, affecting the performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the problem that the closing of one spool on one side of the selection valve in the existing steering flow control valve is likely to cause delay, so that the main spool instantaneously commutes under the action of high-pressure oil, resulting in over-sensitive steering. The present invention provides a steering flow control valve, a hydraulic steering system and a wheeled mobile equipment to avoid the instantaneous commutation of the steering control valve caused by the delay of the spool closing of the selection valve.

[0006] The technical solution for the present invention to achieve its purpose is as follows: Construct a steering flow control valve, which includes a main valve, a left selection valve and a right selection valve, and has a left pilot oil port, a right pilot oil port, a left working oil port, a right working oil port, and a working oil inlet communicating with the P port;

[0007] The left selector valve and the right selector valve are both hydraulically controlled, two-position, five-way valves, having ports C, D, E, F, and G. Port C is connected to the hydraulic control end of the valve stem, and port G is connected to the valve stem spring chamber. When in the left position, ports C and F are connected, ports D and E are connected, and port G is blocked. When in the right position, ports C and F are connected, ports G and E are connected, and port D is blocked.

[0008] The left pilot oil port is connected to the hydraulic control end of the valve stem of the left selector valve, and the right pilot oil port is connected to the hydraulic control end of the valve stem of the right selector valve;

[0009] The f port of the left selector valve is communicated with the valve stem spring chamber of the right selector valve, and the f port of the right selector valve is communicated with the valve stem spring chamber of the left selector valve;

[0010] The d port of the left selector valve is connected to the left working oil port of the main valve in one direction through a one-way valve, and the d port of the right selector valve is connected to the right working oil port of the main valve in one direction through a one-way valve.

[0011] The e port of the left selector valve is connected to the right end of the valve stem hydraulic control of the main valve, and the e port of the right selector valve is connected to the left end of the valve stem hydraulic control of the main valve;

[0012] When the main valve is in the left position, its working oil inlet is connected to the left working oil port. When the main valve is in the right position, its working oil inlet is connected to the right working oil port.

[0013] In the above-mentioned steering flow control valve, the main valve is provided with a left-position pilot oil unloading oil circuit and a right-position pilot oil unloading oil circuit; the left-position pilot oil unloading oil circuit is opened when the main valve is in the left position and is closed in other positions; the right-position pilot oil unloading oil circuit is opened when the main valve is in the right position and is closed in other positions;

[0014] One end of the left-position pilot oil unloading circuit is connected to the left end of the valve stem hydraulic control of the main valve, and the other end is connected to the left working oil port of the main valve in one direction through a one-way valve; one end of the right-position pilot oil unloading circuit is connected to the right end of the valve stem hydraulic control of the main valve, and the other end is connected to the right working oil port of the main valve in one direction through a one-way valve.

[0015] In the above-mentioned steering flow control valve, a throttling groove is provided on both the left pilot oil unloading circuit and the right pilot oil unloading circuit.

[0016] In the above-mentioned steering flow control valve, a throttle hole is provided on the oil passage between port C and port F when the left selector valve and the right selector valve are in the right position.

[0017] In the above-mentioned steering flow control valve, throttle holes are provided on the one-way communicating oil passages between the d ports of the left and right selector valves and the corresponding working oil ports of the main valve.

[0018] In the above-mentioned steering flow control valve, the steering flow control valve further includes a priority valve, an oil inlet of the priority valve is communicated with the P port, and the CF port is communicated with a working oil inlet of the main valve.

[0019] In the above-mentioned steering flow control valve, the steering flow control valve further includes an LS port, and the LS port is communicated with a spring chamber of the priority valve through a throttle orifice.

[0020] In the above-mentioned steering flow control valve, the steering flow control valve further includes a relief valve, an oil inlet end of the relief valve is communicated with the spring chamber of the priority valve, and an oil outlet is communicated with an oil return port of the main valve.

[0021] The technical solution for the present invention to achieve its purpose is as follows: A hydraulic steering system is constructed, including a steering cylinder, a steering gear, a steering pump, and a fuel tank. It is characterized by further including the aforementioned steering flow control valve. A left working oil port and a right working oil port of the steering flow control valve are respectively communicated with a large chamber and a small chamber of the steering cylinder. A left pilot oil port and a right pilot oil port of the steering flow control valve are connected to the steering gear. The P port is connected to the steering pump, and an oil return port of the main valve is communicated with the fuel tank.

[0022] The technical solution for the present invention to achieve its purpose is as follows: A wheeled walking device is constructed, which is characterized by having the aforementioned hydraulic steering system. The wheeled walking device can be a loader, a mining machine, a heavy truck, a large forklift, an agricultural machine, etc.

[0023] Compared with the prior art, in the present invention, the problem of over-sensitive steering caused by the delayed closing of the corresponding right selection valve or left selection valve when pilot oil enters the left pilot oil port or the right pilot oil port is solved. Description of the Drawings

[0024] Figure 1 is a schematic diagram of the steering flow control valve of the present invention.

[0025] Figure 2 is a schematic diagram of the hydraulic steering system of the present invention.

[0026] Names and serial numbers of components in the figure:

[0027] Main valve 10, first overload oil replenishing valve 11, second overload oil replenishing valve 12, first check valve 13, second check valve 14, left-position pilot oil draining oil path 15, right-position pilot oil draining oil path 16, left-position throttle groove 17, right-position throttle groove 18.

[0028] Left selection valve 21, left throttle orifice 22, fourth throttle orifice 23. [[ID=3!]]

[0029] Right selection valve 31, right throttle orifice 32, fifth throttle orifice 33.

[0030] Priority valve 41, relief valve 42, first throttle orifice 43, second throttle orifice 44, third throttle orifice 45.

[0031] Variable pump 50, hydraulic oil tank 51, steering gear 52, steering flow control valve 53, steering cylinder 54, loader working hydraulic system 55. Specific implementation mode

[0032] The following describes the specific implementation mode with reference to the drawings.

[0033] As Figure 1 As shown, this embodiment provides a steering flow control valve 53. The steering flow control valve 53 includes a main valve 10, a left selection valve 21 and a right selection valve 31, and has oil ports such as a left pilot oil port (port a), a right pilot oil port (port b), a left working oil port (port A), a right working oil port (port B), a P port, an LS port, a return oil port (port T), a P1 port, etc. for connecting with external hydraulic components.

[0034] Both the left selection valve 21 and the right selection valve 31 are hydraulic control two-position five-way valves, and both have ports c, d, e, f, and g. Among them, the port c of each selection valve is connected to the hydraulic control end of the valve stem of the selection valve, and the port g is connected to the valve stem spring chamber of the selection valve. When the selection valve is in the left position, the ports c and f are conducted, the ports d and e are conducted, and the port g is cut off; when the selection valve is in the right position, the ports c and f are conducted, the ports g and e are conducted, and the port d is cut off. The right selection valve 31 and the left selection valve 21 are both in the right position in the state shown in Figure 1 When pilot pressure oil enters the left pilot oil port (port a), the left selection valve 21 is in the left position, and the right selection valve 31 is in the normal state and in the right position; when pilot pressure oil enters the right pilot oil port (port b), the right selection valve 3 is in the left position, and the left selection valve 21 is in the normal state and in the right position.

[0035] The left pilot oil port (port a) is connected to the hydraulic control end of the valve stem of the left selection valve 21, and the right pilot oil port (port b) is connected to the hydraulic control end of the valve stem of the right selection valve 31.

[0036] The port f of the left selection valve 21 is connected to the valve stem spring chamber of the right selection valve 31, and the port f of the right selection valve 31 is connected to the valve stem spring chamber of the left selection valve 21.

[0037] The port d of the left selection valve 21 is unidirectionally connected to the left working oil port (port A) of the main valve 10 through the first one-way valve 13, and the port d of the right selection valve 31 is unidirectionally connected to the right working oil port (port B) of the main valve 10 through the second one-way valve 14.

[0038] The port e of the left selection valve 21 is connected to the right hydraulic control end of the valve stem of the main valve 21, and the port e of the right selection valve 31 is connected to the left hydraulic control end of the valve stem of the main valve 10.

[0039] When the main valve 10 is in the left position, its working inlet port is communicated with the left working oil port, and the right working oil port is communicated with the oil return port; when the main valve 10 is in the right position, its working inlet port is communicated with the right working oil port, and the left working oil port is communicated with the oil return port. The working inlet port is communicated with the P port.

[0040] The main valve 10 is provided with a left pilot unloading oil circuit 15 and a right pilot unloading oil circuit 16; the left pilot unloading oil circuit 15 is conducted when the main valve 10 is in the left position and cut off when in the middle position and the right position; the right pilot unloading oil circuit 16 is conducted when the main valve 10 is in the right position and cut off when in the middle position and the left position.

[0041] A left throttling groove 17 is provided on the left pilot unloading oil circuit 15, and a right throttling groove 18 is provided on the right pilot unloading oil circuit 16.

[0042] One end of the left pilot unloading oil circuit 15 is communicated with the left hydraulic control end of the valve stem of the main valve 10, and the other end is communicated with the inlet end of the first check valve 13 and is unidirectionally communicated with the left working oil port of the main valve 10 through the first check valve 13. One end of the right pilot unloading oil circuit 16 is communicated with the right hydraulic control end of the valve stem of the main valve 10, and the other end is unidirectionally communicated with the right working oil port of the main valve 10 through the second check valve 14.

[0043] A left throttle hole 22 is provided on the left selection valve 21. When the left selection valve 21 is in the right position, the c port and the f port are conducted through the left throttle hole 22. When the left selection valve 21 is in the left position, the c port and the f port are directly conducted.

[0044] A right throttle hole 32 is provided on the right selection valve 31. When the right selection valve 31 is in the right position, the c port and the f port are conducted through the right throttle hole 32. When the right selection valve 31 is in the left position, the c port and the f port are directly conducted.

[0045] The d port of the left selection valve 21 is connected to the inlet end of the first check valve 13 through the fourth throttle hole 23. The d port of the right selection valve 31 is connected to the inlet end of the second check valve 14 through the fifth throttle hole 33.

[0046] The inlet port of the priority valve 41 is communicated with the P port, the CF port of the priority valve 41 is communicated with the working inlet port of the main valve 10, and the EF port of the priority valve 41 is used to be connected with the inlet port of the distribution valve of an external oil receiving port, such as the working hydraulic system 55 of a loader, for supplying oil to the outside. The hydraulic control end of the valve stem of the priority valve 41 is communicated with the CF port through the second throttle hole 44, and the valve stem spring cavity of the priority valve 41 is communicated with the CF port through the first throttle hole 43. The CF port is communicated with the P1 port, and oil can be supplied to the outside through the P1 port, such as supplying oil to a steering gear.

[0047] The LS port is communicated with the valve stem spring cavity of the priority valve 41 through the third throttle hole 45, that is, the third throttle hole 45 and the first throttle hole 43 are connected in series between the LS port and the working inlet port of the main valve 10.

[0048] The oil inlet end of the overflow valve 42 communicates with the valve stem spring chamber of the priority valve 41, and the oil outlet end communicates with the oil return port.

[0049] The left working oil port (port A) of the main valve is connected to one end of the first overload oil replenishing valve 11, and the other end of the first overload oil replenishing valve 11 is connected to the oil return port.

[0050] The right working oil port (port B) of the main valve is connected to one end of the second overload oil replenishing valve 11, and the other end of the second overload oil replenishing valve 11 is connected to the oil return port.

[0051] As Figure 2 shown, this embodiment discloses a steering hydraulic system, which includes a variable pump 50, a steering gear 52, a steering flow control valve 53, a steering cylinder 54, a hydraulic oil tank 51, etc.

[0052] The oil suction port of the variable pump 50 is connected to the hydraulic oil tank 51, and the pump port communicates with the P port of the steering flow control valve 53 in the foregoing embodiment. The oil inlet port of the steering gear 52 is connected to the P1 port of the steering flow control valve 53, so as to obtain the pressure oil output by the variable pump 50.

[0053] The left steering pilot oil port and the right steering pilot oil port of the steering gear 52 are correspondingly connected to the left pilot oil port (port a) and the right pilot oil port (port b) of the steering flow control valve 53. The left working oil port (port A) and the right working oil port (port B) of the steering flow control valve 53 are correspondingly connected to the large chamber and the small chamber of the steering cylinder 54. The oil return port of the steering flow control valve 53 communicates with the hydraulic oil tank 51, and the LS port of the steering flow control valve 53 is connected to the flow control port of the variable pump 50. The EF port of the steering flow control valve 53 is connected to the distribution valve of other working hydraulic systems, such as the working hydraulic system 55 of a loader, for supplying the flow of the variable pump to the working hydraulic system of the loader.

[0054] This embodiment discloses a wheeled walking device, which has the foregoing hydraulic steering system, and the steering hydraulic cylinder pushes the steering wheel to deflect for steering control. The wheeled walking device can be a loader, a mining machine, a heavy truck, a large forklift, an agricultural machine, etc.

[0055] In the hydraulic steering system, the variable pump provides pressure oil for steering. The left steering pilot oil port or the right steering pilot oil port of the steering gear outputs high-pressure pilot pressure oil (this pressure oil can be guided to the steering cylinder), and controls the main valve 10 to reverse through the left selection valve 21 and the right selection valve 31. The main valve 10 outputs pressure oil for steering at its left working oil port or right working oil port, and pushes the steering cylinder 54 to extend or contract to achieve steering. The following takes the left pilot oil port (port a) of the steering flow control valve having a pilot pressure oil input as an example to illustrate the steering control principle.

[0056] As shown Figure 1 in FIG. 1, the high-pressure pilot oil output by the steering gear 52 enters the left pilot oil port (port a), acts on the left end of the valve stem of the left selector valve 21 hydraulically, and causes the valve stem of the left selector valve 21 to move, so that the left selector valve is in the left position. The port c and port f of the left selector valve 21 are directly communicated, the port e and port d of the left selector valve 21 are communicated, and the port g of the left selector valve 21 is blocked. The high-pressure pilot oil entering from the left pilot oil port is guided to the port g and the valve stem spring chamber of the right selector valve 31 through the left-position oil passage (communicated port c and port f) of the left selector valve 21.

[0057] The valve stem of the right selector valve 31 moves under the action of the spring force of the spring in the spring chamber and the high-pressure pilot oil, so that the right selector valve 31 is in the right position. The port g and port e of the right selector valve 31 are directly communicated, the port d of the right selector valve 31 is blocked, and the port c and port f of the right selector valve 31 are communicated through the right throttle hole 32. The high-pressure pilot oil is guided to the left end of the valve stem of the main valve 10 hydraulically through the right-position oil passage (communicated port e and port g) of the right selector valve 31. The oil at the right end of the valve stem of the main valve 10 is pushed by the valve stem of the main valve and enters the left working oil port of the main valve 10 through the left-position oil passage (communicated port e and port d) of the left selector valve 21, pushing open the first check valve 13.

[0058] After the valve stem of the main valve 10 moves and reverses to the left position, the high-pressure pilot oil at the left end of the valve stem of the main valve 10 enters the left working oil port through the left-position pilot oil drain oil passage 15 and the first check valve 13 and enters the steering cylinder 54. At the same time, the pilot pressure led out from the left-position pilot oil drain oil passage 15 is transmitted to the port d of the left selector valve 21 through the fourth throttle hole 23 and is transmitted to the right end of the valve stem of the main valve 10 through the left-position oil passage (communicated port d and port e) of the left selector valve 21. The commutation pressure difference at both ends of the valve stem of the main valve 10 is the sum of the pressure drops generated by the left-position throttle groove 17 and the left throttle hole 22.

[0059] In this embodiment, the high-pressure pilot oil flowing into from the left pilot oil port is guided to the left end of the valve stem of the main valve 10 and needs to pass through the left selector valve 21 and the right selector valve 31 in sequence. When the valve stem of the main valve 10 moves under the push of the high-pressure pilot oil at the left end of the valve stem, the oil at the right end of the valve stem of the main valve needs to flow to the left working oil port through the left-position oil passage (communicated port e and port d) of the left selector valve 21 and the first check valve 13; when the valve stem of the left selector valve 21 moves from the left position to the right position, the oil in the valve stem spring chamber of the left selector valve 21 needs to flow through the right-position oil passage (communicated port c and port f) of the right selector valve 31, the right pilot oil port, and the oil return passage of the steering gear. In this embodiment, if the high-pressure pilot oil flows into from the left pilot oil port and the right selector valve 31 delays commutation, the high-pressure pilot oil guided to the left end of the valve stem of the main valve 10 is also delayed accordingly, thus avoiding the problem of instantaneous commutation caused by the high-pressure difference at both ends of the valve stem of the main valve.

[0060] The steering control principle of the high-pressure pilot oil flowing into the right pilot oil port is the same as that of the high-pressure pilot oil flowing into the left pilot oil port.

Claims

1. A steering flow control valve comprising a main valve, a left selector valve, and a right selector valve, and having a left pilot oil port, a right pilot oil port, a left working oil port, a right working oil port, and a working oil inlet connected to a P port; The left selector valve and the right selector valve are both hydraulically controlled, two-position, five-way valves, having ports C, D, E, F, and G. Port C is connected to the hydraulic control end of the valve stem, and port G is connected to the valve stem spring chamber. When in the left position, ports C and F are connected, ports D and E are connected, and port G is blocked. When in the right position, ports C and F are connected, ports G and E are connected, and port D is blocked. The left pilot oil port is connected to the hydraulic control end of the valve stem of the left selector valve, and the right pilot oil port is connected to the hydraulic control end of the valve stem of the right selector valve; The f port of the left selector valve is communicated with the valve stem spring chamber of the right selector valve, and the f port of the right selector valve is communicated with the valve stem spring chamber of the left selector valve; The d port of the left selector valve is connected to the left working oil port of the main valve in one direction through a one-way valve, and the d port of the right selector valve is connected to the right working oil port of the main valve in one direction through a one-way valve. The e port of the left selector valve is connected to the right end of the valve stem hydraulic control of the main valve, and the e port of the right selector valve is connected to the left end of the valve stem hydraulic control of the main valve; When the main valve is in the left position, its working oil inlet is connected to the left working oil port. When the main valve is in the right position, its working oil inlet is connected to the right working oil port.

2. The steering flow control valve according to claim 1, wherein The main valve is provided with a left position pilot oil unloading oil circuit and a right position pilot oil unloading oil circuit; the left position pilot oil unloading oil circuit is opened when the main valve is in the left position and is closed in other positions; the right position pilot oil unloading oil circuit is opened when the main valve is in the right position and is closed in other positions; One end of the left-position pilot oil unloading circuit is connected to the left end of the valve stem hydraulic control of the main valve, and the other end is connected to the left working oil port of the main valve in one direction through a one-way valve; one end of the right-position pilot oil unloading circuit is connected to the right end of the valve stem hydraulic control of the main valve, and the other end is connected to the right working oil port of the main valve in one direction through a one-way valve.

3. The steering flow control valve according to claim 2, characterized in that Both the left pilot oil unloading oil circuit and the right pilot oil unloading oil circuit are provided with throttling grooves.

4. The steering flow control valve according to claim 1, wherein When the left selector valve and the right selector valve are in the right position, a throttle hole is set on the oil passage between port C and port F.

5. The steering flow control valve according to claim 1, characterized in that A throttle hole is provided on the one-way communicating oil path between the D port of the left selection valve and the D port of the right selection valve and the working oil port corresponding to the main valve.

6. The steering flow control valve according to any one of claims 1 to 5, characterized in that The steering flow control valve further comprises a priority valve, the oil inlet of the priority valve is communicated with the P port, and the CF port is communicated with the working oil inlet of the main valve.

7. The steering flow control valve according to claim 6, characterized in that The steering flow control valve further comprises an LS port, which is communicated with the spring chamber of the priority valve via a throttle hole.

8. The steering flow control valve according to claim 6, characterized in that The steering flow control valve further comprises a relief valve, the oil inlet end of the relief valve is communicated with the spring chamber of the priority valve, and the oil outlet is communicated with the oil return port of the main valve.

9. A hydraulic steering system, comprising a steering cylinder, a steering gear, a steering pump, and a fuel tank, characterized in that It also includes a steering flow control valve according to any one of claims 1 to 8, wherein the left working oil port and the right working oil port of the steering flow control valve are respectively connected to the large chamber and the small chamber of the steering cylinder, the left pilot oil port and the right pilot oil port of the steering flow control valve are connected to the steering gear, the P port is connected to the steering pump, and the return oil port of the main valve is connected to the oil tank.

10. A wheeled walking device, characterized in that A hydraulic steering system according to claim 9 is provided.

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