CN217354975U - Pilot cushion valve, hydraulic control loop and engineering machinery - Google Patents

Abstract

The utility model relates to a hydraulic valve, and discloses a pilot buffer valve, which comprises a valve body with a valve cavity, a first one-way throttle valve is arranged between a first oil inlet and a first oil outlet on the valve body, the first one-way throttle valve comprises a first valve core, a first throttling opening is arranged on the first valve core, a second one-way throttle valve is arranged between a second oil inlet and a second oil outlet, the second one-way throttle valve comprises a second valve core, a second throttling opening is arranged on the second valve core, a plunger is arranged between the first one-way throttle valve and the second one-way throttle valve, the plunger is suitable for pushing the second valve core to open under the action of the pressure in the first oil inlet and is suitable for pushing the first valve core to open under the action of the pressure in the second oil inlet, pressure relief channels are arranged on the end faces at both ends of the plunger, the valve core of the main control valve can be ensured to be switched to return slowly and the inertia impact of an executing mechanism can be reduced, and the working stability is high. The utility model also discloses a hydraulic control circuit and an engineering machine tool.

Description

Pilot cushion valve, hydraulic control loop and engineering machinery

Technical Field

The utility model relates to a hydrovalve specifically relates to a guide's cushion valve. Furthermore, the utility model discloses still relate to a hydraulic control circuit and an engineering machine tool.

Background

In order to slow down the time of the valve core of the main control valve returning to the neutral position, a cushion valve is generally arranged between the pilot control valve and the main control valve so as to reduce the effect of inertia impact on an actuating structure (such as a hydraulic oil cylinder or a hydraulic motor).

The working principle of the pilot cushion valve is shown in fig. 1, a pilot control valve 5 is operated to enable pilot pressure oil to enter a first oil inlet a1 of a pilot cushion valve 7 from a first pilot output oil port a, normally reach a first oil outlet a2 through a one-way valve, enter a first pilot control cavity Xa of a main control valve 6, push a valve core of the main control valve 6 to change the direction leftwards, enable the pressure oil output by a working hydraulic pump 82 to enter a rodless cavity of a working hydraulic cylinder 9, and push a piston rod of the working hydraulic cylinder 9 to extend out. At the same time, the oil in the second pilot control chamber Xb of the main control valve 6 that has moved leftward returns to the second oil outlet B2 of the pilot cushion valve 7 through the pipe. Because the pressure oil entering through the first oil inlet A1 opens the check valve between the second oil outlet B2 and the second oil inlet B1 of the pilot cushion valve 7, at the moment, the oil directly returns to the oil tank from the opened check valve, at the moment, the pilot cushion valve 7 does not play a buffering role, and the working hydraulic cylinder 9 acts rapidly. When the pilot control valve 5 stops operating, the first pilot output oil port a of the pilot control valve 5 is connected to the oil tank, the pressure in the first pilot control chamber Xa of the main control valve 6 decreases, the main spool thereof moves rightward under the action of the return spring, and the oil in the first pilot control chamber Xa is pushed to return to the first oil port a2 of the pilot cushion valve 7. Because the first oil inlet a1 has no pressure oil, the check valve between the first oil outlet a2 and the first oil inlet a1 is in a closed state, the pressure oil returned from the first oil outlet B2 can only pass through the throttle orifice between the first oil outlet a2 and the first oil inlet a1, and slowly flows back under the damping action of the throttle orifice, so that the valve core of the main control valve 6 slowly returns to the middle position, and therefore, the extending action of the piston rod of the working hydraulic cylinder 9 is slowly stopped, and the inertia impact when the execution mechanism is stopped is reduced. The principle that the pilot pressure oil is output from the second pilot output oil port b of the pilot control valve 5 is the same, so that the valve core of the main control valve 6 slowly returns from the left valve position and the right valve position, and the inertia impact caused by the quick stop of the actuating mechanism is reduced.

Chinese utility model patent CN 215486908U discloses a pilot cushion valve designed according to this working principle. As shown in fig. 2, the pilot cushion valve comprises a valve body 1, two one-way valves and a plunger 2 located between the two one-way valves are arranged in the valve body 1 along the axial direction; the check valve comprises a valve core 31 and a throttling hole arranged on the valve core 31, the valve body comprises a first oil inlet A1, a first oil outlet A2, a second oil inlet B1 and a second oil outlet B2, the valve cores 31 are respectively arranged between the first oil inlet A1 and the first oil outlet A2 and between the second oil inlet B1 and the second oil outlet B2, and the plunger 2 can push the valve core 31 on one side under the pressure action of the first oil inlet A1 to enable the second oil inlet B1 and the second oil outlet B2 to be communicated, or push the valve core 31 on the other side under the pressure action of the second oil inlet B1 to enable the first oil inlet A1 and the first oil outlet A2 to be communicated. However, the pilot cushion valve has the following defects: when pressure oil entering from the first oil inlet A1 pushes the check valve on the left side to be conducted, the oil pushes the valve core of the main control valve 6 to move left through the first oil outlet A2 and the first pilot control chamber Xa and pushes the oil in the second pilot control chamber Xb to form pressure, and the pressure acts on the right end face of the plunger 2 through the second oil outlet B2 and the throttling hole to resist the pressure of the oil in the first oil inlet A1 acting on the left end face of the plunger 2. This makes the rightward thrust formed on the plunger 2 insufficient to overcome the restoring force of the right spool 31 in the case where the pilot pressure oil pressure in the first oil inlet a1 is low, so that the right spool 31 cannot be opened, and the oil in the second pilot control chamber Xb cannot be quickly returned to the oil tank through the oil passage between the second oil outlet B2 and the second oil inlet B1. Similarly, the pressure oil enters from the second oil inlet B1, which causes the spool of the main control valve 6 not to be rapidly reversed left and right, resulting in slow or no start of the working hydraulic cylinder 9 and the actuator.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a quick supply and the backward flow buffering that guide's hydraulic oil can be realized steadily is provided to guide's cushion valve.

The utility model discloses the technical problem that further will solve provides a hydraulic control circuit, can realize the quick switching-over of main control valve and slow return steadily.

The utility model discloses further technical problem that will solve provides an engineering machine tool, and its actuating mechanism action speed is fast, reliable, and inertia when the action stops strikes for a short time.

In order to solve the above technical problem, an aspect of the present invention provides a pilot buffer valve, which includes a valve body having a valve cavity, the valve body is provided with a first oil inlet, a first oil outlet, a second oil inlet and a second oil outlet, which are respectively connected to the valve cavity, a first one-way throttle valve is disposed between the first oil inlet and the first oil outlet, the first one-way throttle valve includes a first valve core, a first orifice is disposed on the first valve core, a second one-way throttle valve is disposed between the second oil inlet and the second oil outlet, the second one-way throttle valve includes a second valve core, a second orifice is disposed on the second valve core, a plunger is disposed between the first one-way throttle valve and the second one-way throttle valve, the plunger is adapted to push the second valve core to open under the pressure in the first oil inlet, and the pressure in the second oil inlet is suitable for pushing the first valve core to open, and pressure relief channels are arranged on the end faces of the two ends of the plunger.

Preferably, the first one-way throttle valve further comprises a first valve sleeve, a first oil channel is arranged on the first valve sleeve, and the first valve core is installed in the first valve sleeve and can block the first oil channel in one direction under the pushing of a first resetting element; the second one-way throttle valve further comprises a second valve sleeve, a second oil channel is arranged on the second valve sleeve, and the second valve spool is installed in the second valve sleeve and can unidirectionally block the second oil channel under the pushing of a second resetting element. In the preferred technical scheme, the first valve core unidirectionally blocks the first oil duct under the action of the first reset element to form a first one-way throttle valve, the second valve core unidirectionally blocks the second oil duct under the action of the second reset element to form a second one-way throttle valve, the first one-way throttle valve and the second one-way throttle valve are simple in structure, the valve body structures can be taken out from the valve cavity, and the valve body structure is more convenient to machine and maintain.

Further preferably, the first valve sleeve and the second valve sleeve are both provided with valve core cavities, the side wall of each valve core cavity is provided with a valve core oil hole, the first oil inlet is communicated with the first oil outlet through the first oil duct, the valve core cavity and the valve core oil hole, and the second oil inlet is communicated with the second oil outlet through the second oil duct, the valve core cavity and the valve core oil hole; the first valve core and the second valve core respectively comprise a sliding section and a sealing section, the sliding sections can slide in the valve core cavity, the first valve core can move towards the first oil duct direction under the action of the first resetting element, so that the sealing section can seal the first oil duct, and the second valve core can move towards the second oil duct direction under the action of the second resetting element, so that the sealing section can seal the second oil duct. Through the preferred technical scheme, the first valve core and the second valve core can slide in the valve core cavity through the sliding section, and the sealing of the first oil duct and the second oil duct is formed through the sealing section respectively, so that the first oil inlet and the first oil outlet are formed, the one-way conduction between the second oil inlet and the second oil outlet is formed, the sliding of the valve core is flexible, and the opening and the sealing of the oil ducts are reliable.

Further, be provided with on the sealed section with the case through-hole that the case chamber is linked together, just sealed section is including setting up the round platform of first case or second case tip, be provided with the through-flow hole on the terminal surface of round platform, first throttle mouthful with the second throttle mouthful sets up respectively on first case and the second valve core the through-flow hole with between the case through-hole, the plunger includes step portion and sets up the promotion structure of step portion both sides, the promotion structure can pass through the through-flow hole is to the round platform forms the motive force. Through this preferred technical scheme, the promotion structure at plunger both ends can stretch into first oil duct and second oil duct respectively, promotes first valve core and second valve core wherein and opens, and opening of first valve core and second valve core is steady, convenient.

Still further, the land section is located within the valve cavity between the first and second oil inlets, and a middle portion of the land section obstructs the valve cavity. In the preferred technical scheme, the step section not only can separate the first oil inlet and the second oil inlet to prevent oil in the first oil inlet and the second oil inlet from flowing mutually, but also pressure oil in the first oil inlet and the second oil inlet is easier to form a lateral pushing force on the plunger.

Preferably, the pressure relief channel is a pressure relief hole communicating the middle part of the end face of the plunger with the side wall of the plunger. In the preferred technical scheme, the leakage area formed by the pressure relief holes is stable and is less influenced by the external environment.

Preferably, the pressure relief channel is a pressure relief groove which is arranged on the end face of the plunger and penetrates through the side wall of the end face. In the preferred technical scheme, the pressure relief groove has wider leakage flow range and more convenient processing.

Further preferably, the cross-sectional flow area of the pressure relief passage is equal to or greater than the orifice area of the first orifice or the second orifice on the corresponding side. Through this preferred technical scheme, can carry out more effective earial drainage to the fluid that flows out through the choke, prevent that fluid from forming the pressure of countering the plunger removal to the terminal surface of plunger.

The utility model discloses the second aspect provides a hydraulic control return circuit, including pilot control valve, main control valve and the utility model discloses the pilot cushion valve that the first aspect provided, the output hydraulic fluid port of pilot control valve respectively with first oil inlet and second oil inlet are connected, first oil-out and second oil-out respectively with the control hydraulic fluid port at main control valve both ends is connected.

The utility model discloses the third aspect provides engineering machine tool, and this engineering machine tool has used the utility model discloses the hydraulic control return circuit that the second aspect provided.

Through the technical scheme, the utility model discloses a guide's cushion valve is provided with first one-way choke valve between first oil inlet and first oil-out, has set up the one-way choke valve of second between second oil inlet and second oil-out, has realized guide's hydraulic oil between first oil inlet and first oil-out to and the one-way circulation between second oil inlet and the second oil-out. The plunger can open the second one-way throttle valve under the action of the pressure of the first oil inlet, so that when the first oil inlet supplies oil to drive the main control valve to reverse, oil in the other pilot control cavity of the main control valve can flow back through the second oil inlet; meanwhile, the plunger can also open the first one-way throttle valve under the action of the pressure of the second oil inlet, so that when the second oil inlet supplies oil to drive the main control valve to reverse, oil in the other pilot control cavity of the main control valve can flow back through the first oil inlet. And when the first oil inlet and the second oil inlet are not supplied with pilot hydraulic oil, and the main control valve returns to the middle position, the oil liquid reflowing in the pilot control cavity of the main control valve can reflow only through the first throttling port or the second throttling port, so that the oil liquid reflowing speed is slowed down, namely the speed of the main control valve returning to the middle position, and the inertia impact caused by sudden stop of the executing mechanism is reduced. The setting of pressure release passageway on the terminal surface of plunger both ends can prevent that the fluid of backward flow from forming backpressure to the plunger in the main control valve guide control chamber, hinders opening one-way throttle valve smoothly, leads to actuating mechanism action slow or action can not, makes the utility model discloses a guide's cushion valve action reliability is higher with stability, has guaranteed hydraulic control return circuit and engineering machine tool's reliable and stable work.

The utility model discloses a hydraulic control return circuit, owing to used the utility model discloses a guide's cushion valve can guarantee the reliable and stable of main control valve action when realizing quick switching-over, the slow return of main control valve.

The utility model discloses an engineering machine tool is owing to used the utility model discloses a hydraulic control return circuit, actuating mechanism action speed starts soon, and inertia when the action stops strikes for a short time, and simultaneously, the reliability and the stability of action are higher.

Other technical features and advantages of the present invention will be further described in the following detailed description.

Drawings

FIG. 1 is a schematic diagram of a hydraulic control circuit;

FIG. 2 is a schematic diagram of a prior art pilot trim valve;

fig. 3 is a schematic structural diagram of an embodiment of the pilot cushion valve of the present invention;

fig. 4 is a schematic diagram of a first oil inlet supplying state of an embodiment of the pilot cushion valve of the present invention;

FIG. 5 is an enlarged view of a portion I of FIG. 4;

FIG. 6 is an enlarged view of a portion II of FIG. 4;

fig. 7 is a schematic diagram of a plunger structure of an embodiment of the pilot cushion valve of the present invention;

fig. 8 is a schematic diagram of a plunger of another embodiment of the pilot cushion valve of the present invention;

fig. 9 is a schematic view illustrating a first one-way throttle valve according to an embodiment of the pilot cushion valve of the present invention in an opened state;

FIG. 10 is an enlarged view of a portion III of FIG. 9;

fig. 11 is a schematic diagram of a main control valve return state of an embodiment of the pilot cushion valve of the present invention;

fig. 12 is a partial enlarged view of the portion iv in fig. 11.

Description of the reference numerals

1 valve body 2 first one-way throttle valve

21 first spool 22 first orifice

23 first valve pocket 24 first oil passage

25 first reduction element 29 first end cap

3 second check throttle valve 31 second spool

32 second restriction 33 second valve housing

34 second oil passage 35 second reset element

39 second end cap 4 plunger

41 relief channel 42 step

43 push structure 5 pilot control valve

6 main control valve 7 pilot cushion valve

81 pilot hydraulic pump 82 working hydraulic pump

9 first oil inlet of working hydraulic cylinder A1

A2 first oil outlet B1 second oil inlet

B2 second oil outlet

Detailed Description

In the present invention, in the case where no explanation is given to the contrary, the orientation or positional relationship indicated by the terms of orientation such as "left and right" is based on the orientation or positional relationship shown in the drawings of the present invention.

In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted" and "connected" are to be construed broadly, e.g., as meaning a fixed connection, a removable connection, or an integral connection; either directly or indirectly through intervening media, either internally or in any combination thereof. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present invention, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, and therefore the features defined "first", "second" may explicitly or implicitly include one or more of said features.

The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings, and it should be understood that the embodiments described herein are merely for purposes of illustration and explanation, and the scope of the present invention is not limited to the following embodiments.

As shown in fig. 3 to 12, the utility model discloses an embodiment of pilot cushion valve, including valve body 1 and the valve structure of setting in valve body 1, the inside of valve body 1 is provided with the valve pocket, is provided with on the valve body 1 to be used for the first oil inlet a1, first oil-out a2, second oil inlet B1 and the second oil-out B2 be connected with outside hydraulic circuit, and first oil inlet a1, first oil-out a2, second oil inlet B1 and second oil-out B2 are linked together with the valve pocket respectively. A first one-way throttle valve 2 is arranged in a valve cavity between a first oil inlet A1 and a first oil outlet A2, the first one-way throttle valve 2 can adopt various different structural forms, a first valve core 21 is arranged inside the first one-way throttle valve 2, and a first throttling opening 22 which communicates the first oil inlet A1 with the first oil outlet A2 is arranged on the first valve core 21. When the oil flows to the first one-way throttle valve 2 from the first oil inlet a1, the oil can push the first valve core 21 to open, so that the oil can flow to the first oil outlet a2 through the first valve core 21, the flow rate of the oil passing through the first one-way throttle valve 2 is large, and the flow speed is high; when the oil flows from the first oil outlet a2 to the first one-way throttle valve 2, the oil pushes the first valve core 21 to close, so that the oil can only flow to the first oil inlet a1 through the first orifice 22 on the first valve core 21, the through-flow diameter of the first orifice 22 is usually 0.05-2mm, the specific size can be adapted and debugged according to the volume of the pilot control chambers at the two ends of the main control valve 6, and the final debugging effect is set. The first throttling orifice 22 can generate an obvious damping effect on the oil, and under the damping effect of the first throttling orifice 22, the oil has small flow rate and low flowing speed through the first one-way throttle valve 2. A second one-way throttle valve 3 is arranged in the valve cavity between the second oil inlet B1 and the second oil outlet B2, and similarly, the second one-way throttle valve 3 can also adopt various different structural forms, a second valve spool 31 is arranged inside the second one-way throttle valve 3, and a second throttle 32 communicating the second oil inlet B1 and the second oil outlet B2 is arranged on the second valve spool 31. When the oil flows to the second one-way throttle valve 3 from the second oil inlet B1, the oil can push the second valve spool 31 to open, so that the oil can flow to the second oil outlet B2 through the second valve spool 31, and the flow rate of the oil passing through the second one-way throttle valve 3 is large and the flow speed is high; when the oil flows from the second oil outlet B2 to the second one-way throttle valve 3, the oil pushes the second valve core 31 to close, so that the oil can only flow to the second oil inlet B1 through the second throttle orifice 32 of the second valve core 31, similarly, the through-flow diameter of the second throttle orifice 32 is usually between 0.05 mm and 2mm, which can generate an obvious damping effect on the oil, and under the damping effect of the second throttle orifice 32, the flow rate of the oil through the second one-way throttle valve 3 is small, and the flow speed is slow. The plunger 4 is installed between the first one-way throttle valve 2 and the second one-way throttle valve 3, the plunger 4 is arranged such that the pilot hydraulic oil entering from the first oil inlet a1 can push the plunger 4 to move towards the second one-way throttle valve 3 and can open the second spool 31 under the pressure of the pilot hydraulic oil, so that the oil can flow from the second oil outlet B2 to the second oil inlet B1 through the second one-way throttle valve 3 quickly, and the pilot hydraulic oil entering from the second oil inlet B1 can push the plunger 4 to move towards the first one-way throttle valve 3 and can open the first spool 21 under the pressure of the pilot hydraulic oil, so that the oil can flow from the first oil outlet a2 to the first oil inlet a1 through the first one-way throttle valve 3 quickly. Pressure relief passages 41 are arranged on the end faces of the two ends of the plunger 4, so that when the two ends of the plunger 4 contact the first one-way throttle valve 2 or the second one-way throttle valve 3, oil in the first one-way throttle valve 2 or the second one-way throttle valve 3 can flow into the valve cavity through the pressure relief passages 41 on the plunger 4, and the oil is prevented from forming pressure on the end face of the plunger 4.

In some embodiments of the pilot cushion valve of the present invention, as shown in fig. 3, a first valve housing 23 is installed at one end of the valve cavity, a first oil passage 24 is generally disposed at an inner side end of the first valve housing 23 at one end of the first valve housing 23, and the first oil passage 24 is generally disposed between the first oil inlet a1 and the first oil outlet a 2. The first valve core 21 is installed in the first valve sleeve 23, a first resetting element 25 is arranged on one side of the first valve core 21 far away from the first oil channel 24, a first end cover 29 is arranged at the outer side of the first resetting element 25 and at an opening of the valve cavity, normally, the first end cover 29 is fixed at the opening of the valve cavity in a threaded connection mode to form sealing for the opening of the valve cavity, the first resetting element 25 is located between the first end cover 29 and the first valve core 21, the first resetting element 25 can be selected from various devices capable of generating elastic deformation, such as a spiral spring, an air spring, an energy storage tank and the like, preferably, the spiral spring is used, the first resetting element 25 can push the first valve core 21 to generate pressure towards the direction of the first oil channel 24, so that the first oil channel 24 is blocked in one way, and the first one-way throttle valve 2 is formed. A second valve sleeve 33 is mounted at the other end of the valve chamber, and a second oil passage 34 is provided at one end of the second valve sleeve 33, typically the inner end of the second valve sleeve 33, the second oil passage 34 being disposed generally between a second oil inlet B1 and a second oil outlet B2. The second valve spool 31 is installed in the second valve housing 33, a second return element 35 is disposed on a side of the second valve spool 31 away from the second oil channel 34, a second end cap 39 is disposed at an opening of the valve chamber outside the second return element 35, the second end cap 39 is normally fixed at the opening of the valve chamber by a threaded connection to form a seal against the opening of the valve chamber, and the second return element 35 is preferably disposed between the second end cap 39 and the second valve spool 31 by using a coil spring, and is capable of pushing the second valve spool 31 to generate a pressure in a direction of the second oil channel 34, so as to unidirectionally block the second oil channel 34, thereby forming the second one-way throttle valve 3. The valve structures of the first one-way throttle valve 2 and the second one-way throttle valve 3 in the embodiment can be taken out from the valve cavity, and the first one-way throttle valve 2 and the second one-way throttle valve 3 are more convenient to machine, install and maintain.

In some embodiments of the pilot cushion valve of the present invention, as shown in fig. 3, a valve core cavity is disposed inside the first valve sleeve 23 and the second valve sleeve 33, one end of the valve core cavity is open at the end of the valve sleeve, and the other end is communicated with the first oil passage 24 or the second oil passage 34, when the first valve sleeve 23 and the second valve sleeve 33 are installed in the valve cavity, the first oil passage 24 and the second oil passage 34 are located at positions close to the middle of the valve cavity. A spool oil hole is formed in the side wall of the spool cavity, and when the first valve sleeve 23 and the second valve sleeve 33 are installed in the valve cavity, the spool oil hole in the first valve sleeve 23 is communicated with the first oil outlet a2, so that the first oil inlet a1 is communicated with the first oil outlet a2 through the first oil duct 24, the spool cavity and the spool oil hole; the spool oil hole on the second valve sleeve 33 is communicated with the second oil outlet B2, so that the second oil inlet B1 is communicated with the second oil outlet B2 through the second oil passage 34, the spool cavity and the spool oil hole. The first valve core 21 and the second valve core 31 both comprise a sliding section and a sealing section, and are installed in the valve core cavity through the sliding section, so that the first valve core 21 can slide in the valve core cavity along the axial direction of the valve core cavity, the first reset element 25 is installed on one side where the sliding section of the first valve core 21 is located, and under the action of the first reset element 25, the first valve core 21 can move in the direction of the first oil channel 24 in the valve core cavity, so that the sealing section is tightly attached to the first oil channel 24, and the first oil channel 24 is sealed; the second reset element 35 is installed at one side of the sliding section of the second valve spool 31, and under the action of the second reset element 35, the second valve spool 31 can move in the spool cavity towards the second oil passage 34, so that the sealing section is tightly attached to the second oil passage 34 to form a seal for the second oil passage 34.

In some embodiments of the pilot cushion valve of the present invention, as shown in fig. 3, a valve core through hole communicated with the valve core cavity is provided on the sealing section of the first valve core 21 and the second valve core 31, and generally, the valve core through hole penetrates through the sealing section along a diameter direction of the sealing section. The end part of the sealing section is in a circular truncated cone shape, a through hole is arranged in the center of the end face of the circular truncated cone, the first throttling port 22 is arranged between the through hole of the first valve core 21 and the through hole of the valve core, and the second throttling port 32 is arranged between the through hole of the second valve core 31 and the through hole of the valve core. The plunger 4 comprises a step portion 42 located in the middle, pushing structures 43 are arranged on two sides of the step portion 42, the pushing structures 43 are various mechanical structures capable of forming a pushing effect on the first valve element 21 and the second valve element 31, and are preferably cylinders with diameters smaller than the first oil channel 24 and the second oil channel 34, the plunger 4 can move in the valve cavity, so that the pushing structures 43 can enter the first oil channel 24 to contact with a circular truncated cone end face of the first valve element 21 to push the first valve element 21 to be opened, or enter the second oil channel 34 to contact with a circular truncated cone end face of the second valve element 31 to push the second valve element 31 to be opened.

As a specific embodiment of the pilot cushion valve of the present invention, as shown in fig. 3, the stage 42 of the plunger 4 is located between the first oil inlet a1 and the second oil inlet B1 in the valve cavity, and the middle of the stage 42 separates the valve cavity. When the pilot hydraulic oil enters the valve cavity through the first oil inlet a1, on the one hand, the pilot hydraulic oil can enter the first oil passage 24 and push the first valve spool 21 to open, and on the other hand, the plunger 4 can be pushed to move towards the second valve spool 31, so that the second valve spool 31 can be pushed to open by the pushing structure 43. When the pilot hydraulic oil enters the valve cavity through the second oil inlet B1, on the one hand, the pilot hydraulic oil can enter the second oil passage 34 to push the second valve core 31 to open, and on the other hand, the plunger 4 can be pushed to move towards the first valve core 21, so that the first valve core 21 can be pushed to open by the pushing structure 43

In some embodiments of the pilot cushion valve of the present invention, as shown in fig. 7, a pressure relief hole communicating with the plunger 4 at the same side end side wall is provided in the middle of the end faces at both sides of the plunger 4, and the pressure relief hole forms a pressure relief passage 41.

In some embodiments of the pilot cushion valve of the present invention, as shown in fig. 8, pressure relief grooves penetrating through side walls on both sides of the end surface are provided on both side end surfaces of the plunger 4, and the pressure relief grooves are formed as pressure relief passages 41. Specifically, one or more pressure relief grooves may be provided, and a plurality of pressure relief grooves may be arranged in parallel, in a cross arrangement, or at an angle on the end surface, and preferably two pressure relief grooves are provided that cross each other perpendicularly on the end surface. Of course, the pressure relief channel 41 on the end surface of the plunger 4 may also be a pressure relief groove extending from the middle of the end surface to one side wall and penetrating through the side wall, and when a plurality of pressure relief grooves are provided, the plurality of pressure relief grooves may be communicated with each other.

In some embodiments of the pilot cushion valve of the present invention, the cross-sectional area of the pressure relief channel 41 on both end surfaces of the plunger 4 is greater than or equal to the throttle area of the first throttle orifice 22 or the second throttle orifice 32 on the corresponding side. Thus, the oil flowing out through the first orifice 22 or the second orifice 32 can be smoothly discharged into the valve chamber through the relief passage 41, and the oil is prevented from forming thrust against both side end faces of the plunger 4.

The utility model discloses an embodiment of hydraulic control return circuit, including pilot control valve 5, main control valve 6 and the utility model discloses the pilot cushion valve of any embodiment. An oil inlet P1 of the pilot control valve 5 is connected with a pilot hydraulic pump 81, an oil return port T1 is connected with a hydraulic oil tank, an output oil port a and an output oil port B of the pilot control valve 5 are respectively connected with a first oil inlet A1 and a second oil inlet B1, a first oil outlet A2 and a second oil outlet B2 are respectively connected with a first pilot control cavity Xa and a second pilot control cavity Xb at two ends of the main control valve 6, an oil inlet P of the main control valve 6 is in linear connection with a working hydraulic pump 82, the oil return port T is connected with the hydraulic oil tank, a first working oil port A of the main control valve 6 is connected with a rod cavity of the working hydraulic cylinder 9, and a second working oil port B is connected with a rodless cavity of the working hydraulic cylinder 9.

The operation of the pilot cushion valve of the present invention will be described below with reference to the embodiment shown in fig. 3 by way of example with reference to the hydraulic control circuit shown in fig. 1.

1. When the hydraulic system does not work, the pilot control valve 5 is not operated, no pilot hydraulic oil enters the first oil inlet A1 and the second oil inlet B1, no pilot hydraulic oil enters the first oil outlet A2 and the second oil outlet B2, the main control valve 5 is located at a middle position, and the working hydraulic cylinder 4 does not act. At this time, as shown in fig. 3, the plunger 4 in the pilot cushion valve 7 is located at an intermediate position in the valve chamber, and the valve ports between the first spool 21 and the first valve sleeve 23 and the valve ports between the second spool 31 and the second valve sleeve 33 are both closed, and no oil flows through both the first orifice 22 and the second orifice 22.

2. When the pilot control valve 5 is operated and pilot hydraulic oil is output through the output oil port a of the pilot control valve 5, the pilot hydraulic oil enters the pilot cushion valve 7 through the first oil inlet a 1. At this time, as shown in fig. 4 to fig. 6, the pressure oil entering the valve cavity is divided into two paths, one path of the pressure oil enters the first oil passage 24, pushes the first valve core 21 to move leftward against the acting force of the first resetting element 25, opens the first one-way throttle valve 2, so that the pressure oil normally reaches the first oil outlet a2 from the first oil inlet a1 through the pilot cushion valve 7, and reaches the first pilot control cavity Xa of the main control valve 6 along the hydraulic pipeline, so as to push the main valve core to reverse to the left side, and the high-pressure oil output by the working hydraulic pump 82 enters the rodless cavity of the working hydraulic cylinder 9, so as to push the actuator to do work or move. The other path of pressure oil pushes the plunger 4 to move towards the right, the pushing structure 43 of the plunger 4 enters the second oil passage 34, contacts the second valve spool 31, and pushes the second valve spool 31 to continuously move towards the right against the acting force of the second resetting element 35, so that the second one-way throttle valve 3 is opened. Meanwhile, as the spool of the main control valve 6 moves to the left, the oil in the second pilot control chamber Xb is pushed to flow out, returns to the second oil outlet B2 of the pilot cushion valve 7, normally passes through the open channel between the second valve sleeve 33 and the second spool 31, reaches the second oil inlet B1, and returns to the hydraulic oil tank through the oil return port T of the pilot control valve 5. In this state, the pilot hydraulic oil passes through the oil path of the pilot cushion valve 7 smoothly, the valve core of the main control valve 6 moves at a high speed, and the starting and running speeds of the execution structure are high.

3. When the pilot hydraulic oil is output from the output oil port a of the pilot control valve, as shown in fig. 9 and 10, the pilot hydraulic oil entering the pilot cushion valve 7 through the first oil inlet a1 is divided into two paths, and the first one-way cushion valve 2 is pushed to open and the plunger 4 is pushed to move towards the second one-way cushion valve 3. If the first one-way cushion valve 2 is opened first, at the moment, pilot hydraulic oil flows out from the first oil outlet A2 through the first one-way cushion valve 2, enters the first pilot control cavity Xa of the main control valve 6, pushes the valve core of the main control valve 9 to move towards the left side, and the valve core of the main control valve 9 pushes oil in the second pilot control cavity Xb to enter the second one-way cushion valve 3 from the second oil outlet B2 and flow out along the valve core through hole, the second throttling opening 32 and the through hole. When the plunger 4 is pushed by another pilot hydraulic oil to move rightwards, the pushing structure 43 enters the second oil passage 34, and the end face of the pushing structure 43 contacts the end face of the circular truncated cone of the sealing section of the second valve core 31, if the pressure relief channel 41 is not arranged at the end part of the pushing structure 43, the pushing structure 43 can block the oil flowing out of the through hole, and the blocked oil can generate thrust in the left direction on the plunger 4 to resist the rightward thrust formed on the left side of the plunger 4 by the pilot hydraulic oil entering from the first oil inlet a 1. If the thrust formed by the pilot hydraulic oil on the left side of the plunger 4 is smaller than or equal to the sum of the leftward thrust generated by the blocked hydraulic oil on the right side of the plunger 4 and the leftward thrust generated by the second reset element 35, the plunger 4 cannot push the second valve spool 31 to move rightwards, the second one-way buffer valve 3 cannot be opened, and the main control valve 5 cannot be reversed, or the direction can be reversed after the pressure of the pilot hydraulic oil is further increased, so that the working hydraulic cylinder 9 cannot move or the movement is delayed, and the smooth operation of the actuating mechanism is influenced.

After the pressure relief channel 41 is arranged on the end surfaces of the pushing structures 43 on the two sides of the plunger 4, the oil flowing out of the through hole flows into the valve cavity from the pressure relief channel 41, and the oil return tank is released from the second oil inlet B1, the pressure of the oil flowing out of the through hole on the right side of the plunger 4 is very small and even close to zero, the pilot hydraulic oil can smoothly push the plunger 4 to open the second valve spool 3, and the oil in the second pilot control cavity Xb returns to the second oil inlet B1 through the opened second one-way throttle valve 3 and returns to the hydraulic oil tank through the oil return port T of the pilot control valve 5.

4. When the control of the pilot control valve 5 is stopped, no pilot hydraulic oil is output from the output oil port a and the output oil port b of the pilot control valve 5, the pressure in the first pilot control chamber Xa of the main control valve 6 is reduced, the spool of the main control valve 6 moves rightwards under the action of the return spring to return to the neutral position, and the oil in the first pilot control chamber Xa is pushed to return to the first oil outlet a2 of the pilot cushion valve 7. As shown in fig. 11 and 12, since the first oil inlet a1 has no pilot hydraulic oil input at this time, the valve core 21 of the one-way throttle valve 2 moves rightward under the action of the first reset element 25, closing the fluid flow channel between the first valve sleeve 23 and the first valve core 21, and the fluid returning from the first oil outlet a2 can only flow through the first orifice 22 on the first valve core 21, and pressure is built up and slowly released under the damping action of the first orifice 22, so that the valve core of the main control valve 6 slowly returns to the neutral position, and the movement of the working hydraulic cylinder 9 is slowly stopped, thereby achieving the effect of reducing the inertia shock of the actuator.

5. The process of controlling the pilot control valve 5 to output the pilot hydraulic oil through the output oil port b is the same as the working principle of outputting the pilot hydraulic oil through the output oil port a.

The utility model discloses an embodiment of engineering machine tool has used the utility model discloses the hydraulic control return circuit of any embodiment also has above-mentioned advantage.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "a specific implementation," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In the present disclosure, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited thereto. The technical idea of the present invention is that it is possible to combine the simple variants of the technical solution of the present invention, including each specific technical feature, in any suitable way. These simple variations and combinations should also be considered as disclosed in the present invention, all falling within the scope of protection of the present invention.

Claims (10)

1. A pilot buffer valve comprises a valve body (1) with a valve cavity, and is characterized in that a first oil inlet (A1), a first oil outlet (A2), a second oil inlet (B1) and a second oil outlet (B2) which are respectively connected with the valve cavity are arranged on the valve body (1), a first one-way throttle valve (2) is arranged between the first oil inlet (A1) and the first oil outlet (A2), the first one-way throttle valve (2) comprises a first valve core (21), a first throttle opening (22) is arranged on the first valve core (21), a second one-way throttle valve (3) is arranged between the second oil inlet (B1) and the second oil outlet (B2), the second one-way throttle valve (3) comprises a second valve core (31), a second throttle opening (32) is arranged on the second valve core (31), and a plunger (4) is arranged between the first one-way throttle valve (2) and the second one-way throttle valve (3), the plunger (4) is suitable for pushing the second valve core (31) to open under the action of pressure in the first oil inlet (A1) and pushing the first valve core (21) to open under the action of pressure in the second oil inlet (B1), and pressure relief channels (41) are arranged on the end faces of two ends of the plunger (4).

2. The pilot trim valve according to claim 1, characterized in that the first one-way throttle valve (2) further comprises a first valve sleeve (23), a first oil passage (24) is arranged on the first valve sleeve (23), the first valve spool (21) is installed in the first valve sleeve (23) and can unidirectionally block the first oil passage (24) under the pushing of a first reset element (25); the second one-way throttle valve (3) further comprises a second valve sleeve (33), a second oil channel (34) is arranged on the second valve sleeve (33), and the second valve spool (31) is installed in the second valve sleeve (33) and can be pushed by a second reset element (35) to unidirectionally block the second oil channel (34).

3. The pilot cushion valve according to claim 2, wherein the first valve sleeve (23) and the second valve sleeve (33) are provided with valve core cavities, the side walls of the valve core cavities are provided with valve core oil holes, the first oil inlet (a1) is communicated with the first oil outlet (a2) through the first oil passage (24), the valve core cavity and the valve core oil holes, and the second oil inlet (B1) is communicated with the second oil outlet (B2) through the second oil passage (34), the valve core cavity and the valve core oil holes; the first valve core (21) and the second valve core (31) both comprise a sliding section and a sealing section and can slide in the valve core cavity through the sliding section, the first valve core (21) can move towards the first oil channel (24) under the action of the first resetting element (25), so that the sealing section can seal the first oil channel (24), and the second valve core (31) can move towards the second oil channel (34) under the action of the second resetting element (35), so that the sealing section can seal the second oil channel (34).

4. The pilot cushion valve according to claim 3, wherein the sealing section is provided with a valve core through hole communicated with the valve core cavity, the sealing section comprises a circular truncated cone arranged at the end of the first valve core (21) or the second valve core (31), a through hole is arranged on the end surface of the circular truncated cone, the first throttling port (22) and the second throttling port (32) are respectively arranged between the through hole on the first valve core (21) and the second valve core (31) and the valve core through hole, the plunger (4) comprises a step portion (42) and pushing structures (43) arranged at two sides of the step portion (42), and the pushing structures (43) can form a pushing force on the circular truncated cone through the through hole.

5. The pilot trim valve according to claim 4, characterized in that the step (42) is located in the valve chamber between the first (A1) and second (B1) oil inlets, and a middle portion of the step (42) blocks the valve chamber.

6. The pilot cushion valve according to any one of claims 1 to 5, wherein the relief passage (41) is a relief hole communicating a middle portion of an end surface of the plunger (4) with a side wall of the plunger (4).

7. The pilot cushion valve according to any one of claims 1 to 5, wherein the pressure relief passage (41) is a pressure relief groove provided on an end face of the plunger (4) and penetrating a side wall of the end face.

8. The pilot trim valve according to any one of claims 1 to 5, characterized in that the cross-sectional flow area of the pressure relief channel (41) is equal to or greater than the throttle area of the first throttle orifice (22) or the second throttle orifice (32) of the respective side.

9. A hydraulic control circuit, characterized by comprising a pilot control valve (5), a main control valve (6) and the pilot cushion valve according to any one of claims 1 to 8, wherein the output oil port of the pilot control valve (5) is respectively connected with the first oil inlet (A1) and the second oil inlet (B1), and the first oil outlet (A2) and the second oil outlet (B2) are respectively connected with the control oil ports at two ends of the main control valve (6).

10. A working machine, characterized by comprising a hydraulic control circuit according to claim 9.

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