Load holding valve and loader hydraulic system

Abstract

The application discloses a load holding valve and a loader hydraulic system in the technical field of mechanical hydraulic systems, and aims to solve the problem that the load holding valve and the travel stability module of the loader cannot be compatible in the prior art. The load holding valve comprises a spool valve and a reversing valve. The number of the reversing valve is 2, and the reversing valve is respectively a first reversing valve and a second reversing valve. The oil inlet of the spool valve is communicated with the A port of the load holding valve. The oil outlet of the spool valve is communicated with the B port, the E port and the L port of the load holding valve and the oil inlet of an internal spring cavity. The oil outlet of the spring cavity is communicated with the oil outlet of the spool valve through the first reversing valve oil inlet and the internal oil channel at the initial position. The oil outlet of the first reversing valve is communicated with the oil inlet of the second reversing valve, and the control port of the first reversing valve is communicated with the P1 port of the load holding valve. The two ends of the second reversing valve are respectively communicated with the A port and the B port of the load holding valve. The application can solve the problem that the load holding valve and the travel stability module cannot be compatible, and simultaneously realize the boom locking function.

Description

TECHNICAL FIELD

[0001] The present application relates to a load holding valve and a loader hydraulic system, and belongs to the technical field of mechanical hydraulic systems. BACKGROUND

[0002] In engineering machinery, in order to improve the safety of the use of the loader, in order to prevent the soft pipe connected with the oil cylinder from being broken during lifting and lowering, and to cause the lifting equipment to fall or the lowering speed to be too fast, the loader is provided with a load holding valve to realize the lifting and lowering of the boom. The loader is also provided with a stabilizing module valve. When the loader travels on a bumpy road section, the stabilizing module function is opened, and the accumulator absorbs the pressure impact of the rodless chamber of the boom cylinder, thereby playing a damping role.

[0003] However, when the load control valve is used together with the stabilizing module valve, that is, when the loader travels on a bumpy road section and the stabilizing module function is opened, the pressure oil of the accumulator can enter the rodless chamber of the boom cylinder through the load holding valve, but the load holding valve has no control pressure, so that the spring chamber of the cone valve of the load holding valve is in a closed state, the cone valve cannot be opened, and the hydraulic oil in the rodless chamber of the boom cylinder cannot flow to the accumulator through the load holding and stabilizing module valve, so that the impact of the boom cannot be absorbed, and the damping effect cannot be achieved. Therefore, in the existing technology, the load holding valve and the travel stabilizing module cannot be compatible. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a load control valve and a loader hydraulic system, which can solve the problem of the incompatibility of the load holding valve and the travel stabilizing module, and simultaneously realize the boom locking function.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] On the one hand, the present application provides a load holding valve, which comprises a cone valve and a reversing valve. The number of the reversing valve is 2, which are a first reversing valve and a second reversing valve. The oil inlet of the cone valve is communicated with the A port of the load holding valve, and the oil outlet thereof is communicated with the B port, the E port and the L port of the load holding valve and the oil inlet of the internal spring chamber. The oil outlet of the spring chamber is communicated with the oil outlet of the cone valve through the internal oil channel of the first reversing valve and the initial position thereof. The oil outlet of the first reversing valve is communicated with the oil inlet of the second reversing valve, and the control port thereof is communicated with the P1 port of the load holding valve. The two ends of the second reversing valve are respectively communicated with the A port and the B port of the load holding valve.

[0007] Further, a first overflow valve is arranged on the oil channel through which the oil outlet of the cone valve is communicated with the L port of the load holding valve.

[0008] Further, a plurality of dampings are further included, respectively a first damping and a second damping, the first damping is arranged on an oil channel of the oil outlet of the spool valve and the oil inlet of the internal spring cavity, and the second damping is arranged on an oil channel of the oil outlet of the spool valve and the E port of the load holding valve.

[0009] In another aspect, the application provides a hydraulic system of a loader, including two load holding valves according to any one of the above, the E ports of the two load holding valves are connected, and the A ports of the two load holding valves are connected through a third damping, and the B ports of the two load holding valves are connected with the rodless cavity of the boom cylinder.

[0010] Further, a pump, a multi-way valve and a stabilizing module valve are further included, the oil inlet of the pump is connected with the hydraulic oil tank, and the oil outlet is connected with the P port of the multi-way valve; the T port of the multi-way valve is connected with the hydraulic oil tank, so that the hydraulic oil flows back to the hydraulic oil tank; the A1 port of the multi-way valve is connected with the A port of the load holding valve, the B1 port is connected with the rod cavity of the boom cylinder, and the A2 and B2 ports are connected with the rodless cavity and the rod cavity of the dump cylinder respectively;

[0011] The A port of the stabilizing module valve is connected with the A port of the load holding valve, the B port is connected with the rod cavity of the boom cylinder, the X port is connected with the oil inlet of the accumulator, the DX port is connected with the oil outlet of the pump, and the L and T ports are connected with the hydraulic oil tank.

[0012] Further, the multi-way valve includes a boom joint and a dump joint, the boom joint is a reversing valve for controlling the lifting and lowering actions of the boom cylinder, and the dump joint is a reversing valve for controlling the bucket collecting and unloading actions of the dump cylinder.

[0013] Further, a shuttle valve is further included, the A port of the shuttle valve is connected with the b2 port of the pilot valve, the B port is connected with the P1 port of the stabilizing module valve, and the C port is connected with the P1 port of the load holding valve.

[0014] Further, a pilot valve is further included, the a1, a2, b1 and b2 ports of the pilot valve are connected with the pilot oil ports a1, a2, b1 and b2 of the multi-way valve respectively.

[0015] Further, the pilot valve is provided with a pilot oil source valve, the oil inlet of the pilot oil source valve is connected with the oil outlet of the pump, and the oil outlet is connected with the oil inlets of the pilot valve and the Pst port of the stabilizing module valve.

[0016] Compared with the prior art, the application has the following beneficial effects:

[0017] The load holding valve provided by the application can open the spool valve in it according to the pressure change of the boom rodless cavity during the running bump of the loader, so that the accumulator is communicated with the boom rodless cavity, the accumulator absorbs the pressure impact of the boom rodless cavity, so as to achieve the damping effect, solve the problem that the load holding valve and the stability module valve cannot be compatible, and realize the boom locking function. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural schematic view of the load holding valve in an embodiment of the application.

[0019] Figure 2 It is a structural schematic view of the hydraulic system of the loader in an embodiment of the application.

[0020] In the figure: 1 pump, 2 multi-way valve, 3 load holding valve, 31 spool valve, 32 first reversing valve, 33 second reversing valve, 34 overflow valve, 35 first damping, 36 second damping, 4 pilot valve, 5 stability module valve, 51 first electromagnetic valve, 52 second electromagnetic valve, 53 third reversing valve, 54 fourth reversing valve, 55 second overflow valve, 516 accumulator, 7 hydraulic oil tank, 8 boom cylinder, 9 third damping, 10 shuttle valve, 11 pump, 12 pilot oil source valve, 13 dump cylinder. EMBODIMENT

[0021] The application will be further described below in conjunction with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0022] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In the description of the application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0023] In the description of the application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances. EMBODIMENT

[0024] like Figure 1 As shown, an embodiment of the present invention provides a load holding valve 3, which has ports A, B, E, L, and P1. It includes a cone valve 31 and a reversing valve. The number of reversing valves is two, namely a first reversing valve 32 and a second reversing valve 33, wherein the first reversing valve 32 is a two-position three-way valve.

[0025] The inlet of cone valve 31 is connected to port A of load holding valve 3, and the outlet is connected to port B of load holding valve 3. The outlet of cone valve 31 is connected to the inlet of first directional valve 32. The outlet of first directional valve 32 is connected to the inlet of second directional valve 33. Its control port is connected to port P1 of load holding valve 3. The left and right ends of second directional valve 33 are connected to ports A and B of load holding valve 3, respectively.

[0026] The oil outlet of the cone valve 31 is also connected to the oil inlet of the internal spring cavity through the first damper 35, to the E port of the load holding valve 3 through the second damper 36, and to the L port of the load holding valve 3 through the overflow valve 34. The oil outlet of the spring cavity is connected to the oil outlet of the cone valve 31 through the internal oil passage of the first directional valve 32 in its initial position. Example

[0027] like Figure 2 As shown, this embodiment of the invention provides a hydraulic system for a loader, including two load holding valves 3 as described in Embodiment 1. The E ports of the two load holding valves 3 are connected and connected to their A ports through a third damper 9. The B port of the load holding valve 3 is connected to the rodless chamber of the boom cylinder 8.

[0028] The hydraulic system includes pump 1, multi-way valve 2, and stabilizing module valve 5. The oil inlet of pump 1 is connected to hydraulic oil tank 7, and its oil outlet is connected to port P of multi-way valve 2. Pump 1 draws hydraulic oil from hydraulic oil tank 7 and outputs high-pressure oil, which flows to port P of multi-way valve 2.

[0029] The multi-way valve 2 has a boom linkage and a bucket linkage. The boom linkage is a directional valve that controls the lifting and lowering actions of the boom cylinder 8, and the bucket linkage is a directional valve that controls the bucket retraction and unloading actions of the bucket cylinder 13. The T port of the multi-way valve 2 is connected to the hydraulic oil tank 7, allowing hydraulic oil to flow back to the hydraulic oil tank 7. The A1 port is connected to the A port of the load holding valve 3, the B1 port is connected to the rod chamber of the boom cylinder 8, and the A2 and B2 ports are connected to the rodless chamber and rod chamber of the bucket cylinder 13, respectively.

[0030] Multi-way valve 2 is a pilot-operated multi-way valve, and its four oil ports a1, a2, b1, and b2 are respectively connected to the four oil ports a1, a2, b1, and b2 of pilot valve 4.

[0031] It also includes a shuttle valve 10, whose A port is connected to the b2 port of the pilot valve 4, its B port is connected to the P1 port of the stabilization module valve 5, and its C port is connected to the P1 port of the load holding valve 3.

[0032] When the boom cylinder 8 needs to be lifted, the pilot pressure oil at port a1 of the pilot valve 4 flows to port a1 of the multi-way valve 2, controlling the boom linkage of the multi-way valve 2 to move to the left, thus switching the boom linkage of the multi-way valve 2 to the right position. This allows the high-pressure oil from pump 1 to flow through the boom linkage to port A1 of the multi-way valve 2 and port A of the load holding valve 3. When the pressure difference between port A and port B of the load holding valve 3 exceeds a set value, the high-pressure oil at port A of the load holding valve 3 pushes the cone valve 31 to move. The hydraulic oil in the spring chamber of the cone valve 31 flows back to the outlet of the cone valve 31 through its internal oil passage. The cone valve 31 is connected to port B of the load holding valve 3, allowing the high-pressure oil to flow from port A of the load holding valve 3 through the cone valve 31 to port B of the load holding valve 3 and into the rodless chamber of the boom cylinder 8, thus lifting the boom cylinder 8. At this time, the hydraulic oil in the rod chamber of the boom cylinder 8 flows back to the hydraulic oil tank 7 through the multi-way valve 2.

[0033] When it is necessary to control the boom cylinder 8 to descend, the pilot pressure oil at port b2 of the pilot valve 4 flows to port b2 of the multi-way valve 2, controlling the boom coupling of the multi-way valve 2 to move to the right, so that the boom coupling of the multi-way valve 2 switches to the left position. At this time, port P of the multi-way valve 2 is connected to port B1, and port A1 is connected to port T. The hydraulic oil flows through the boom coupling to port B1 of the multi-way valve 2.

[0034] Simultaneously, the pilot pressure oil at port b2 of pilot valve 4 flows through shuttle valve 10 to port P1 of load holding valve 3. Port P1 of load holding valve 3 controls the first directional valve 32 to switch, and the first directional valve 32 is in the left position. The spring chamber of cone valve 31 is connected to the inlet of second directional valve 33 through the oil passage of the left position of the first directional valve 32. Port A1 of multi-way valve 2 is connected to port T of multi-way valve 2 through the oil passage of the boom of multi-way valve 2, so that the pressure on the left side of the second directional valve 33 of load holding valve 3 is greater than the pressure on the right side. The second directional valve 33 moves to the right, and the outlet of the first directional valve 32 is connected to port A of load holding valve 3 through the second directional valve 33.

[0035] At this time, a pressure difference is formed before and after the first damper 35 of the load holding valve 3, which causes the load holding valve 3 and the cone valve 31 to open. The B port of the load holding valve 3 is connected to the A port of the load holding valve 3. The hydraulic oil can flow from the B port of the load holding valve 3 to the A port, pass through the multi-way valve 2, and flow to the hydraulic oil tank 7 to realize the boom lowering function.

[0036] When there is no pilot pressure oil flowing to multi-way valve 2 through pilot valves a1 and b2, load holding valve 3 is locked. When the loader is traveling on bumpy roads, boom cylinder 8 may be under pressure, causing the pressure in the rodless chamber of boom cylinder 8 to increase. Boom cylinder 8 may also be under tension, causing the pressure in the rodless chamber of boom cylinder 8 to decrease, making it unstable during travel.

[0037] Therefore, the hydraulic system also includes a stabilizing module valve 5, whose A port is connected to the A port of the load holding valve 3, its B port is connected to the rod chamber of the boom cylinder 8, its X port is connected to the oil inlet of the accumulator 6, its DX port is connected to the oil outlet of the pump 1, and its L and T ports are connected to the hydraulic oil tank 7.

[0038] Specifically, the stabilizing module valve 5 includes a first solenoid valve 51, a second solenoid valve 52, a third directional valve 53, a fourth directional valve 54, and a second relief valve 55. The third directional valve 53 is a two-position five-way valve. In the initial position, port 1 is connected to port B of the stabilizing module valve 5, port 2 is connected to port A of the stabilizing module valve 5, port 3 is connected to port T of the stabilizing module valve 5, port 4 is connected to port 5, and port 5 is connected to port X of the stabilizing module valve 5. When port 1 is connected to port 3, and port 2 is connected to port 5, the accumulator 6 is connected to port A of the stabilizing module valve 5, and port B of the stabilizing module valve 5 is connected to port T of the stabilizing module valve 5. At this time, the accumulator 6 can absorb the pressure impact from the automatic arm cylinder 8.

[0039] When the stabilization module function is activated, the second solenoid valve 52 of the stabilization module valve 5 is energized first, and after a set time, the first solenoid valve 51 is energized.

[0040] When the second solenoid valve 52 is energized, the hydraulic oil in the accumulator 6 passes through ports 5 and 4 of the third directional valve 53, then through the left end of the second solenoid valve 52, and finally reaches the right end of the fourth directional valve 54. This, combined with the pressure from port A at the left end of the third directional valve 53, controls the movement of the third directional valve 53. When the pressure at the right end of the fourth directional valve 54 is higher than the pressure at the left end, the pressure oil in the accumulator 6 can be released to port T through the right position of the fourth directional valve 54. When the pressure at the left end of the fourth directional valve 54 is higher than the pressure at the right end, the pressure oil in the accumulator 6 can be flushed into the accumulator 6 through the left position of the fourth directional valve 54. When the pressures at both ends of the fourth directional valve 54 are equal, the pressure in the accumulator 6 is connected to port A of the load holding valve 3.

[0041] After the first solenoid valve 51 is energized, the pilot pressure oil at port Pst passes through the first solenoid valve 51 to the left end of the third directional valve 53, controlling the third directional valve 53 to switch. After the third directional valve 53 switches, ports 1 and 3 of the third directional valve 53 are connected, and ports 2 and 5 are connected. At this time, the accumulator 6 is connected to port A of the stabilization module valve 5 and port A of the load holding valve 3.

[0042] The E port of the load holding valve 3 is connected to the A1 port of the multi-way valve 2 through the third damper 9. During loading and driving, the third damper 9 balances the pressure of the B port of the load holding valve 3 and the A1 port of the multi-way valve 2, as well as the pressure of the A port of the stabilization module valve 5, thereby balancing the pressure in the rodless chamber of the boom cylinder 8 and the accumulator 6. When the stabilization module is activated, the pressures of the boom cylinder 8 and the accumulator 6 are the same, preventing the boom from lowering or raising.

[0043] After the first solenoid valve 51 is energized and reversed, the hydraulic oil from the outlet of the pilot oil source valve 12 reaches the Pst port of the stabilization module valve 5 and then flows through the first solenoid valve 51 to the third directional valve 53 and the B port of the shuttle valve 10. The C port of the shuttle valve 10 is connected to the P1 port of the load holding valve 3. The hydraulic oil at the P1 port controls the first directional valve 32 to reverse. The reversal of the first directional valve 32 makes the cone valve spring chamber of the load holding valve 3 communicate with the second directional valve 33. The two ends of the second directional valve 33 are connected to the A port and the B port of the load holding valve 3, respectively.

[0044] When the loader is traveling on bumpy roads, if the pressure at port A of the load holding valve 3 (i.e., the pressure in accumulator 6) is high, the pressurized oil released by accumulator 6 flows through the cone valve to the rodless chamber of the boom cylinder 8. When the rodless chamber of the boom cylinder 8 is pressurized, the pressure at port B of the load holding valve 3 is greater than the pressure at port A, causing the first directional valve 32 to move to the right. The hydraulic oil at port B of the cone valve passes through the first damper 35 to the spring chamber of the cone valve 31, then through the first directional valve 32 to the inlet of the second directional valve 33. It then flows through the internal oil passage of the second directional valve 33 to port A of the load holding valve, where the pressure is lower, and finally to the accumulator 6. This allows the accumulator 6 to absorb the pressure impact of the boom cylinder 8 and release pressurized oil to the boom cylinder 8, achieving the effect of boom shock absorption.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A load-holding valve, characterized in that, The system includes a cone valve and two directional valves, namely a first directional valve and a second directional valve. The inlet of the cone valve is connected to port A of the load holding valve, and its outlet is connected to ports B, E, and L of the load holding valve, as well as the inlet of the internal spring chamber. The outlet of the spring chamber is connected to the outlet of the cone valve through the inlet of the first directional valve and its internal oil passage in its initial position. The outlet of the first directional valve is connected to the inlet of the second directional valve, and its control port is connected to port P1 of the load holding valve. The two ends of the second directional valve are connected to ports A and B of the load holding valve, respectively. The pressure difference between ports A and B of the load holding valve controls the second directional valve, so that the pressure on the left side of the second directional valve is greater than the pressure on the right side, and the second directional valve moves to the right. The oil outlet of the first directional valve is connected to port A of the load holding valve through the second directional valve. It also includes a first damper, which is located on the oil passage connecting the oil outlet of the cone valve and the oil inlet of the internal spring cavity.

2. The load holding valve according to claim 1, characterized in that, A first overflow valve is provided on the oil passage connecting the oil outlet of the cone valve and the L port of the load holding valve.

3. The load holding valve according to claim 1, characterized in that, It also includes a second damper, which is located in the oil passage connecting the outlet of the cone valve and the E port of the load holding valve.

4. A hydraulic system for a loader, characterized in that, It includes two load holding valves as described in any one of claims 1 to 3, the E ports of the two load holding valves are connected and connected to their A ports through a third damper, and the B port of the load holding valve is connected to the rodless chamber of the boom cylinder.

5. The loader hydraulic system according to claim 4, characterized in that, It also includes a pump, a multi-way valve, and a stabilizing module valve. The pump's inlet is connected to the hydraulic oil tank, and its outlet is connected to the P port of the multi-way valve. The T port of the multi-way valve is connected to the hydraulic oil tank, allowing the hydraulic oil to flow back to the hydraulic oil tank. The A1 port of the multi-way valve is connected to the A port of the load holding valve, the B1 port is connected to the rod chamber of the boom cylinder, and the A2 and B2 ports are connected to the rodless chamber and rod chamber of the tipping cylinder, respectively. The A port of the stabilizing module valve is connected to the A port of the load holding valve, the B port is connected to the rod chamber of the boom cylinder, the X port is connected to the oil inlet of the accumulator, the DX port is connected to the oil outlet of the pump, and the L and T ports are connected to the hydraulic oil tank.

6. The loader hydraulic system according to claim 5, characterized in that, The multi-way valve includes a boom linkage and a bucket linkage. The boom linkage is a reversing valve that controls the lifting and lowering actions of the boom cylinder, and the bucket linkage is a reversing valve that controls the bucket retraction and unloading actions of the bucket cylinder.

7. The loader hydraulic system according to claim 5, characterized in that, It also includes a shuttle valve, wherein port A of the shuttle valve is connected to port b2 of the pilot valve, port B is connected to port P1 of the stabilization module valve, and port C is connected to port P1 of the load holding valve.

8. The loader hydraulic system according to claim 5, characterized in that, It also includes a pilot valve, whose ports a1, a2, b1, and b2 are respectively connected to the pilot ports a1, a2, b1, and b2 of the multi-way valve.

9. The loader hydraulic system according to claim 8, characterized in that, The pilot valve is equipped with a pilot oil source valve. The oil inlet of the pilot oil source valve is connected to the oil outlet of the pump, and its oil outlet is connected to the oil inlet of the pilot valve and the Pst port of the stabilization module valve.

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