CN219366439U - Bidirectional hydraulic lock - Google Patents

Abstract

The utility model belongs to the technical field of hydraulic pressure, and discloses a bidirectional hydraulic lock, which comprises a main valve body, a control piston and two one-way valves, wherein a first accommodating cavity penetrating the main valve body along a first direction is arranged in the main valve body, the control piston is arranged in the first accommodating cavity in a sliding manner and divides the first accommodating cavity into a first valve cavity and a second valve cavity, and first liquid outlets of the two one-way valves are respectively communicated with corresponding working oil ports. The check valve comprises a second valve body, a main valve core and a main reset spring, wherein the main valve core and the main reset spring are arranged in the second valve body, and one end, close to the main reset spring, of the main valve core is enclosed with the second valve body to form a third valve cavity. The main valve core comprises a core body and a buffering one-way valve arranged in the core body, a second liquid inlet of the buffering one-way valve is communicated with the first liquid outlet, a second liquid outlet of the buffering one-way valve is communicated with the third valve cavity, a throttle oil duct is arranged on the main valve core and is used for communicating the third valve cavity and a corresponding working oil port.

Description

Bidirectional hydraulic lock

Technical Field

The utility model relates to the technical field of hydraulic pressure, in particular to a bidirectional hydraulic lock.

Background

The bidirectional hydraulic lock generally consists of a valve body, a control piston and two hydraulic control one-way valves, wherein the two hydraulic control one-way valves take the pressure of an opposite oil way as pilot oil, when one pipeline has no pressure, the other is closed at the same time, and when one pipeline has pressure, the other is opened at the same time. The bidirectional hydraulic lock can reliably stop the weight and the actuating mechanism at any position required by work, and plays a role in locking and pressure maintaining. However, the existing bidirectional hydraulic lock is not buffered in the opening process, abrupt changes in pressure and flow exist, and the impact of the system is large.

Accordingly, there is a need for a two-way hydraulic lock that addresses the above-described issues.

Disclosure of Invention

The utility model aims to provide a bidirectional hydraulic lock which is stable, slow and impact-free in the opening process, quick in response and high in closing speed.

To achieve the purpose, the utility model adopts the following technical scheme:

the bidirectional hydraulic lock comprises a main valve body, a control piston and two check valves, wherein a first accommodating cavity penetrating the main valve body along a first direction is arranged in the main valve body, the control piston is arranged in the first accommodating cavity in a sliding manner and divides the first accommodating cavity into a first valve cavity and a second valve cavity, the two check valves are respectively arranged at two ends of the first accommodating cavity, an oil inlet communicated with the first valve cavity, an oil return port communicated with the second valve cavity and working oil ports in one-to-one correspondence with the check valves are arranged on the main valve body, first liquid inlets of the two check valves are respectively communicated with the first valve cavity and the second valve cavity, and first liquid outlets of the two check valves are respectively communicated with the corresponding working oil ports;

the one-way valve comprises a second valve body, a main valve core and a main reset spring, wherein the main valve core and the main reset spring are arranged in the second valve body, two ends of the main reset spring are respectively abutted against the second valve body and the main valve core, one end, close to the main reset spring, of the main valve core is enclosed with the second valve body to form a third valve cavity, and the control piston can extend into a first liquid inlet of the one-way valve to drive the main valve core so as to open the one-way valve;

the main valve core comprises a core body and a buffering one-way valve arranged in the core body, a second liquid inlet of the buffering one-way valve is communicated with the first liquid outlet, a second liquid outlet of the buffering one-way valve is communicated with the third valve cavity, and a throttle oil duct is arranged on the main valve core and is used for communicating the third valve cavity and the corresponding working oil port.

Preferably, the main valve body, the second valve body, the main valve element and the control piston are all coaxially arranged.

Preferably, the core is far away from one end of the control piston is provided with the second and holds the chamber, the buffering check valve includes first plug, buffering case and buffering reset spring, first plug set up in the second holds the chamber and keep away from one end of the control piston, the buffering check valve with buffering reset spring all set up in the second holds the intracavity, the both ends of buffering reset spring respectively with first plug and buffering case butt, the second holds the intracavity and is provided with around the first backstop portion of second holds the chamber, buffering case keeps away from one end of first plug is provided with around the first butt portion of buffering case, buffering reset spring can order about the first butt portion of buffering case with first backstop portion butt, be provided with the oil return hole on the core, the oil return hole intercommunication the second inlet of buffering check valve with the first liquid outlet of check valve, the second inlet of buffering check valve is arranged in on the first plug.

Preferably, an overflow gap is arranged between the side wall of the buffer valve core and the cavity wall of the second accommodating cavity, the throttle oil duct is arranged on the first abutting part, and the throttle oil duct is communicated with the overflow gap and the buffer one-way valve liquid inlet.

Preferably, a first limit groove is formed in one end, close to the control piston, of the first plug, a second limit groove is formed in one end, far away from the control piston, of the buffer valve core, one end of the buffer reset spring stretches into the first limit groove, and the other end of the buffer reset spring stretches into the second limit groove.

Preferably, the liquid outlet of the buffering one-way valve is communicated with the first limiting groove, and the buffering valve core is provided with an overflow hole which is communicated with the second limiting groove and the overflow gap.

Preferably, a first liquid guide groove surrounding the main valve core is formed in the outer side wall of the main valve core, and the first liquid outlet and the oil return hole are both communicated to the first liquid guide groove.

Preferably, the cavity wall of the first accommodating cavity is provided with a second liquid guide groove surrounding the first accommodating cavity, the second liquid guide groove is arranged in one-to-one correspondence with the first liquid guide groove, and the working oil port is communicated with the second liquid guide groove.

Preferably, the second valve body comprises a valve sleeve and a second plug, one end of the valve sleeve extends into the first accommodating cavity and is in sealing connection with the main valve body, a first liquid outlet of the one-way valve is formed in the side wall of the valve sleeve, and the second plug seals one end of the valve sleeve away from the control piston.

Preferably, a third limit groove is formed in one end, close to the control piston, of the second plug, a second stop portion is arranged on the outer wall of one end, far away from the control piston, of the main valve core, one end of the main return spring extends into the third limit groove, and the other end of the main return spring is sleeved on the main valve core and is in butt joint with the second stop portion.

The utility model has the beneficial effects that:

when the bidirectional hydraulic lock with higher oil inlet pressure is opened, the high-pressure hydraulic oil entering the first valve cavity through the oil inlet pushes the one-way valve connected with the first valve cavity to be opened, the main valve core compresses the main return spring, hydraulic oil in the third valve cavity is discharged through the throttle oil duct of the one-way valve, meanwhile, the high-pressure hydraulic oil in the first valve cavity pushes the control piston to prop open the main valve core of the one-way valve communicated with the second valve cavity, hydraulic oil in the third valve cavity in the one-way valve is discharged through the throttle oil duct of the one-way valve, and the discharge speed of the hydraulic oil in the third valve cavity is slowed down through the throttle oil duct, so that the bidirectional hydraulic lock is stable and slow without impact in the opening process. When the bidirectional hydraulic lock with lower oil inlet pressure is closed, the main return spring pushes the main valve core to return, the pressure in the third valve cavity is reduced, the second liquid inlet of the buffer check valve is opened, hydraulic oil rapidly enters the third valve cavity through the second liquid inlet, and the main valve core rapidly returns to close the check valve, so that rapid response is ensured when the bidirectional hydraulic lock is closed.

Drawings

FIG. 1 is a cross-sectional view of a two-way hydraulic lock provided by an embodiment of the present utility model;

fig. 2 is an enlarged view at a in fig. 1.

In the figure:

1. a main valve body;

2. a control piston; 21. a butt joint rod;

3. a one-way valve;

31. a second valve body; 311. a valve sleeve; 312. a second plug;

32. a main spool;

321. a core; 3211. a first stop portion;

322. a buffer check valve; 3221. a first plug; 3322. a buffer valve core; 33221. a first abutting portion; 3223. a buffer return spring;

323. a second stop portion;

33. a main return spring;

4. a seal ring;

10. a first valve chamber; 20. a second valve chamber;

30. an oil inlet; 40. an oil return port; 50. a first liquid inlet; 60. a first liquid outlet; 70. a third valve chamber; 80. a second liquid inlet; 90. a second liquid outlet; 100. a throttle oil passage; 110. an oil return hole; 120. an overcurrent gap; 130. an overflow hole; 140. a third limit groove; 150. a first liquid guiding groove; 160. a second liquid guiding groove; 170. a third liquid guiding groove; 180. and a fourth liquid guiding groove.

Detailed Description

The utility model is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present utility model are shown in the drawings.

In the description of the present utility model, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

In the present utility model, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", and the like are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the utility model. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.

As shown in fig. 1 and 2, the present embodiment provides a bidirectional hydraulic lock, including a main valve body 1, a control piston 2 and two check valves 3, wherein a first accommodating cavity penetrating the main valve body 1 along a first direction is provided in the main valve body 1, the control piston 2 is slidably disposed in the first accommodating cavity and divides the first accommodating cavity into a first valve cavity 10 and a second valve cavity 20, the two check valves 3 are respectively disposed at two ends of the first accommodating cavity, an oil inlet 30 communicated with the first valve cavity 10, an oil return port 40 communicated with the second valve cavity 20 and working oil ports corresponding to the check valves 3 one by one are provided on the main valve body 1, a first liquid inlet 50 of the two check valves 3 is respectively communicated with the first valve cavity 10 and the second valve cavity 20, and a first liquid outlet 60 of the two check valves 3 is respectively communicated with the corresponding working oil ports. The check valve 3 comprises a second valve body 31, a main valve core 32 and a main reset spring 33, the main valve core 32 and the main reset spring 33 are arranged in the second valve body 31, two ends of the main reset spring 33 are respectively abutted against the second valve body 31 and the main valve core 32, one end, close to the main reset spring 33, of the main valve core 32 is enclosed with the second valve body 31 to form a third valve cavity 70, and the control piston 2 can extend into a first liquid inlet 50 of the check valve 3 to drive the main valve core 32 so as to open the check valve 3. The main valve core 32 comprises a core 321 and a buffering one-way valve 322 arranged in the core 321, a second liquid inlet 80 of the buffering one-way valve 322 is communicated with the first liquid outlet 60, a second liquid outlet 90 of the buffering one-way valve 322 is communicated with the third valve cavity 70, a throttle oil duct 100 is arranged on the main valve core 32, and the throttle oil duct 100 is used for communicating the third valve cavity 70 and a corresponding working oil port.

In the bidirectional hydraulic lock provided in this embodiment, when the bidirectional hydraulic lock with higher pressure in the oil inlet 30 is opened, the high-pressure hydraulic oil entering the first valve cavity 10 through the oil inlet 30 pushes the one-way valve 3 connected with the first valve cavity 10 to be opened, the main valve core 32 compresses the main return spring 33, hydraulic oil in the third valve cavity 70 is discharged through the throttle oil duct 100 of the one-way valve 3, meanwhile, the high-pressure hydraulic oil in the first valve cavity 10 pushes the control piston 2 to push the main valve core 32 of the one-way valve 3 communicated with the second valve cavity 20, hydraulic oil in the third valve cavity 70 in the one-way valve 3 is also discharged through the throttle oil duct 100 of the one-way valve 3, and the discharge speed of hydraulic oil in the third valve cavity 70 is slowed down by setting the throttle oil duct 100, so that the bidirectional hydraulic lock opening process is smooth and slow without impact. When the bidirectional hydraulic lock with lower pressure in the oil inlet 30 is closed, the main return spring 33 pushes the main valve core 32 to return, the pressure in the third valve cavity 70 is reduced, the second liquid inlet 80 of the buffer check valve 322 is opened, and hydraulic oil rapidly enters the third valve cavity 70 through the second liquid inlet 80, so that the main valve core 32 rapidly returns to close the check valve 3, and the response is rapid when the bidirectional hydraulic lock is closed.

The smaller the flow passage sectional area of the throttle oil duct 100, the slower the opening speed of the bidirectional hydraulic lock, the more stable the opening, and the flow passage sectional area of the throttle oil duct 100 is specifically designed and selected according to the needs.

Alternatively, as shown in fig. 1, the main valve body 1, the second valve body 31, the main valve element 32 and the control piston 2 are all coaxially arranged, so that the control piston 2 can push the main valve element 32 open.

Optionally, as shown in fig. 1 and 2, an end of the core 321 away from the control piston 2 is provided with a second accommodating cavity, the buffer check valve 322 includes a first plug 3221, a buffer valve core 3322 and a buffer return spring 3223, the first plug 3221 is disposed at an end of the second accommodating cavity away from the control piston 2, the buffer check valve 322 and the buffer return spring 3223 are all disposed in the second accommodating cavity, two ends of the buffer return spring 3223 are respectively abutted with the first plug 3221 and the buffer valve core 3322, a first stop portion 3211 surrounding the second accommodating cavity is disposed in the second accommodating cavity, a first abutment portion 33221 surrounding the buffer valve core 3322 is disposed at an end of the buffer valve core 3322 away from the first plug 3221, the buffer return spring 3223 can drive the first abutment portion 33221 of the buffer valve core 3322 to abut against the first stop portion 3211, the oil return hole 110 is disposed on the core 321, the second liquid inlet 80 of the buffer check valve 322 is communicated with the first liquid outlet 60 of the check valve 3, and the second liquid outlet 60 of the buffer check valve 322 is disposed on the first plug 3221. The core 321 and the first plug 3221 cooperate to serve as a valve body of the buffering one-way valve 322, and the second liquid inlet 80 of the buffering one-way valve 322 is communicated with the first liquid outlet 60 of the one-way valve 3 through the oil return hole 110.

Optionally, as shown in fig. 1 and fig. 2, an overflow gap 120 is disposed between a side wall of the buffer valve core 3322 and a cavity wall of the second accommodating cavity, the throttle oil duct 100 is disposed on the first abutting portion 33221, and the throttle oil duct 100 communicates the overflow gap 120 with a liquid inlet of the buffer check valve 322. When the bidirectional hydraulic lock is opened, hydraulic oil in the third valve cavity 70 reaches the second liquid inlet 80 through the second liquid outlet 90, the overflow gap 120 and the throttle oil duct 100, and is discharged out of the check valve 3 through the oil return hole 110.

Optionally, as shown in fig. 1 and fig. 2, one end of the first plug 3221, which is close to the control piston 2, is provided with a first limiting groove, one end of the buffer valve core 3322, which is far away from the control piston 2, is provided with a second limiting groove, one end of the buffer return spring 3223 extends into the first limiting groove, and the other end extends into the second limiting groove. The first and second limit grooves play a limiting role on the buffer return spring 3223, and prevent the buffer return spring 3223 from being dislocated. In the present embodiment, the first limit groove, the second limit groove, and the buffer return spring 3223 all extend in the first direction.

Alternatively, as shown in fig. 1 and 2, the liquid outlet of the buffer check valve 322 is connected to the first limiting groove, and the buffer valve core 3322 is provided with an overflow hole 130 for communicating the second limiting groove with the overflow gap 120. So that the through-flow gap 120 is communicated with the second liquid inlet 80 of the buffering one-way valve 322 on the first plug 3221 through the flow hole 130, the second limiting groove and the first limiting groove.

Optionally, as shown in fig. 1, a first liquid guiding groove 150 surrounding the main valve core 32 is provided on the outer side wall of the main valve core 32, and the first liquid outlet 60 and the oil return hole 110 are both connected to the first liquid guiding groove 150, so that the oil passing hole 110 can keep communicating with the first liquid outlet 60 when the main valve core 32 slides.

Further, as shown in fig. 1, the wall of the first accommodating cavity is provided with a second liquid guiding groove 160 surrounding the first accommodating cavity, the second liquid guiding groove 160 is arranged in one-to-one correspondence with the first liquid guiding groove 150, and the working oil port and the liquid outlet of the one-way valve 3 are both communicated to the second liquid guiding groove 160, so that the communication between the oil passing hole 110 and the first liquid outlet 60 is further facilitated when the main valve core 32 slides.

Optionally, as shown in fig. 1, the second valve body 31 includes a valve sleeve 311 and a second plug 312, one end of the valve sleeve 311 extends into the first accommodating cavity and is in sealing connection with the main valve body 1, the first liquid outlet 60 of the one-way valve 3 is disposed on a side wall of the valve sleeve 311, and the second plug 312 plugs one end of the valve sleeve 311 away from the control piston 2.

Optionally, a third limit groove 140 is provided at one end of the second plug 312 close to the control piston 2, a second stop portion 323 is provided on an outer wall of one end of the main valve core 32 far away from the control piston 2, one end of the main return spring 33 extends into the third limit groove 140, and the other end of the main return spring 33 is sleeved on the main valve core 32 and abuts against the second stop portion 323, so that dislocation of the main return spring 33 in the repeated expansion and contraction process is avoided.

Optionally, a third liquid guiding groove 170 and a fourth liquid guiding groove 180 surrounding the first accommodating cavity are further arranged on the cavity wall of the first accommodating cavity, the oil inlet 30 is communicated to the third liquid guiding groove 170, the oil return opening 40 is communicated to the fourth liquid guiding groove 180, and communication between the oil inlet 30 and the oil return opening 40 and the first liquid inlet 50 of the corresponding one-way valve 3 is convenient to maintain.

Optionally, two ends of the control piston 2 are respectively provided with a supporting rod 21, and the supporting rods 21 are used for extending into the liquid inlet of the one-way valve 3 to drive the main valve core 32, so that the control piston 2 can conveniently extend into the first liquid inlet 50 of the one-way valve 3.

Optionally, the bidirectional hydraulic lock provided in this embodiment further includes a sealing ring 4, a fourth limiting groove surrounding the main valve core 32 is provided on the outer wall of the main valve core 32, and the sealing ring 4 is sleeved in the fourth limiting groove, and is used for sealing a gap between the main valve core 32 and the main valve body 1.

It is to be understood that the above examples of the present utility model are provided for clarity of illustration only and are not limiting of the embodiments of the present utility model. Various obvious changes, rearrangements and substitutions can be made by those skilled in the art without departing from the scope of the utility model. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the utility model are desired to be protected by the following claims.

Claims (10)

1. The bidirectional hydraulic lock is characterized by comprising a main valve body (1), a control piston (2) and two one-way valves (3), wherein a first accommodating cavity penetrating through the main valve body (1) along a first direction is arranged in the main valve body (1), the control piston (2) is arranged in the first accommodating cavity in a sliding mode and divides the first accommodating cavity into a first valve cavity (10) and a second valve cavity (20), the two one-way valves (3) are respectively arranged at two ends of the first accommodating cavity, an oil inlet (30) communicated with the first valve cavity (10), an oil return port (40) communicated with the second valve cavity (20) and working oil ports in one-to-one correspondence with the one-way valves (3) are arranged on the main valve body (1), and first liquid inlets (50) of the two one-way valves (3) are respectively communicated with the first valve cavity (10) and the second valve cavity (20) and first liquid outlets (60) of the two one-way valves (3) are respectively communicated with the corresponding working oil ports;

the one-way valve (3) comprises a second valve body (31), a main valve core (32) and a main reset spring (33), wherein the main valve core (32) and the main reset spring (33) are arranged in the second valve body (31), two ends of the main reset spring (33) are respectively abutted to the second valve body (31) and the main valve core (32), one end, close to the main reset spring (33), of the main valve core (32) is enclosed with the second valve body (31) to form a third valve cavity (70), and the first liquid inlet (50) of the control piston (2) can extend into the one-way valve (3) to drive the main valve core (32) so as to open the one-way valve (3);

the main valve core (32) comprises a core body (321) and a buffering one-way valve (322) arranged in the core body (321), a second liquid inlet (80) of the buffering one-way valve (322) is communicated with the first liquid outlet (60), a second liquid outlet (90) of the buffering one-way valve (322) is communicated with the third valve cavity (70), a throttle oil duct (100) is arranged on the main valve core (32), and the throttle oil duct (100) is used for being communicated with the third valve cavity (70) and the corresponding working oil port.

2. A two-way hydraulic lock according to claim 1, characterized in that the main valve body (1), the second valve body (31), the main valve spool (32) and the control piston (2) are all coaxially arranged.

3. The bidirectional hydraulic lock according to claim 1, wherein a second accommodating cavity is provided at one end of the core body (321) away from the control piston (2), the buffer check valve (322) comprises a first plug (3221), a buffer valve core (3322) and a buffer return spring (3223), the first plug (3221) is provided at one end of the second accommodating cavity away from the control piston (2), the buffer check valve (322) and the buffer return spring (3223) are both disposed in the second accommodating cavity, two ends of the buffer return spring (3223) are respectively abutted with the first plug (3221) and the buffer valve core (3322), a first stop portion (3211) surrounding the second accommodating cavity is disposed in the second accommodating cavity, one end of the buffer valve core (3322) away from the first plug (3221) is provided with a first abutment portion (33221) surrounding the buffer valve core (3322), the buffer return spring (322) can drive the buffer valve core (32222) to be in fluid communication with the first stop portion (3360) of the first valve core (3360), the second liquid outlet (90) of the buffering one-way valve (322) is arranged on the first plug (3221).

4. The bidirectional hydraulic lock according to claim 3, wherein an overflow gap (120) is provided between the side wall of the buffer valve core (3322) and the cavity wall of the second accommodating cavity, the throttle oil duct (100) is disposed on the first abutting portion (33221), and the throttle oil duct (100) communicates the overflow gap (120) with the liquid inlet of the buffer check valve (322).

5. The bidirectional hydraulic lock according to claim 4, wherein a first limit groove is provided at one end of the first plug (3221) close to the control piston (2), a second limit groove is provided at one end of the buffer valve core (3322) away from the control piston (2), one end of the buffer return spring (3223) extends into the first limit groove, and the other end extends into the second limit groove.

6. The two-way hydraulic lock according to claim 5, wherein the liquid outlet of the buffering one-way valve (322) is communicated with the first limiting groove, and the buffering valve core (3322) is provided with an overflow hole (130) which is communicated with the second limiting groove and the overflow gap (120).

7. A two-way hydraulic lock according to claim 3, wherein a first liquid guiding groove (150) surrounding the main valve core (32) is arranged on the outer side wall of the main valve core (32), and the first liquid outlet (60) and the oil return hole (110) are both communicated to the first liquid guiding groove (150).

8. The bidirectional hydraulic lock according to claim 7, wherein a second liquid guiding groove (160) surrounding the first accommodating cavity is arranged on a cavity wall of the first accommodating cavity, the second liquid guiding groove (160) is arranged in one-to-one correspondence with the first liquid guiding groove (150), and the working oil port is communicated to the second liquid guiding groove (160).

9. The bidirectional hydraulic lock according to claim 1, wherein the second valve body (31) comprises a valve sleeve (311) and a second plug (312), one end of the valve sleeve (311) extends into the first accommodating cavity and is in sealing connection with the main valve body (1), the first liquid outlet (60) of the one-way valve (3) is arranged on the side wall of the valve sleeve (311), and the second plug (312) seals off one end of the valve sleeve (311) away from the control piston (2).

10. The bidirectional hydraulic lock according to claim 9, wherein a third limit groove (140) is arranged at one end of the second plug (312) close to the control piston (2), a second stop portion (323) is arranged on the outer wall of one end of the main valve core (32) far away from the control piston (2), one end of the main return spring (33) extends into the third limit groove (140), and the other end of the main return spring is sleeved on the main valve core (32) and is abutted against the second stop portion (323).