Pressure reduction overflow valve for pilot handle

Abstract

The pressure reducing overflow valve comprises a main valve body and two valve element assemblies, the main valve body is provided with two mounting cavities used for mounting the valve element assemblies, each mounting cavity is provided with a port P, a port A and a port T. Each valve element assembly comprises a pressure reducing valve element, a piston rod, a reset spring and a pressure reducing spring, and the piston rod and the pressure reducing valve element are sequentially and coaxially arranged; the pressure reducing valve element is sleeved with the pressure reducing spring, and the pressure reducing valve element is sleeved with the pressure reducing spring. The end, away from the piston rod, of the mounting cavity is provided with an avoiding hole allowing the pressure reducing valve element to stretch out and draw back, the end, away from the limiting part, of the pressure reducing valve element is provided with a drainage hole, one end of the drainage hole communicates with the T opening, and the other end of the drainage hole communicates with the avoiding hole of the main valve body. The drainage hole formed in the pressure reducing valve element replaces a hole in the main valve body, leakage of oil in the main valve body can be reduced, and the reliability of a system can be improved.

Description

Technical Field

[0001] This application relates to the field of excavating machinery, and more particularly to a pressure relief valve for a pilot handle. Background Technology

[0002] The core function of the excavator pilot system is to precisely control the operation of the high-pressure main hydraulic system through a low-pressure pilot oil circuit, enabling sensitive and stable operation of various working devices of the excavator (such as the boom, stick, bucket, travel, and swing). The key control components in the excavator pilot system that use a low-pressure pilot oil circuit to control the operation of the high-pressure main hydraulic system are two pressure-reducing relief valves. These valves are switched using a pilot handle. The pressure-reducing relief valve is a proportional pressure control valve, typically installed below the operating handles in the cab. It outputs corresponding control oil pressure based on the operator's handle travel, causing a corresponding movement of the main control valve core, thereby controlling the speed of the working devices.

[0003] Figure 1 The existing pressure-reducing relief valve shown mainly consists of a main valve body and two valve core assemblies. The two valve core assemblies are respectively installed in two mounting chambers of the main valve body. The mounting chambers of the main valve body have ports P, A, and T, with port A located between ports P and T. Each valve core assembly includes a pressure-reducing valve core, a piston rod, a spring seat, a return spring, and a pressure-reducing spring. The piston rod and the pressure-reducing valve core are arranged coaxially in sequence and are both installed in the mounting chambers. The mounting chambers have mounting ports for one end of the piston rod to extend out. When the operator tilts the pilot handle toward one of the valve core assemblies, the pilot handle pushes the piston rod of that valve core assembly to move, thereby causing the pressure-reducing valve core of that valve core assembly to overcome the elastic force of the return spring and move axially, switching the valve core assembly to the working state. When the pilot handle is returned to the neutral position, the return spring drives the piston rod and the pressure-reducing valve core to move and reset.

[0004] The principle behind the pressure-reducing relief valve is that the diameter of the pressure-reducing valve core differs on both sides of the P port position. This difference in diameter creates a pressure-bearing area of ​​the valve core within the oil on both sides of the P port, subjecting the valve core to an axial force. This force causes the valve core to overcome the elasticity of the pressure-reducing spring and move axially into the pre-reserved receiving hole inside the piston rod. During this axial movement, the size of the oil passage in the pressure-reducing relief valve changes, thus producing a pressure-reducing effect.

[0005] In order to enable the valve core to move smoothly under the pressure of the oil, in the prior art, the mounting chamber on the main valve body that mates with the pressure reducing valve core is designed to be open at the end, so that the mounting chamber is connected to the return oil pipeline of the hydraulic system. In this case, the number of external pipeline connection points of the main valve body is increased, which in turn increases the number of leakage points of the main valve body and affects the reliability of the pressure reducing relief valve. Summary of the Invention

[0006] In order to improve the problem that the external pipeline on the main valve body designed to accommodate the movement of the pressure reducing valve core increases the possibility of leakage in the main valve body, this application provides a pressure reducing relief valve for the pilot handle.

[0007] The pressure-reducing relief valve for pilot handle provided in this application adopts the following technical solution: A pressure-reducing relief valve for a pilot handle includes a main valve body and two valve core assemblies. The main valve body has two mounting chambers for mounting the valve core assemblies. Each mounting chamber has a P port, an A port, and a T port, with the A port located between the P port and the T port. Each valve core assembly includes a pressure-reducing valve core, a piston rod, a return spring, and a pressure-reducing spring. The piston rod and the pressure-reducing valve core are coaxially arranged sequentially and both are mounted within the mounting chambers. Each mounting chamber has a mounting opening for one end of the piston rod to extend out. The pressure-reducing spring is sleeved on the pressure-reducing valve core, and the return spring is sleeved around the pressure-reducing spring. A spring seat is provided between the return spring and the piston rod. The spring seat is sleeved on the pressure reducing valve core. The end of the pressure reducing valve core near the piston rod is provided with a limiting part. The piston rod is provided with a receiving hole for accommodating the limiting part. The spring seat can prevent the limiting part from dislodging from the receiving hole. The pressure reducing spring can force the limiting part to abut against the spring seat. The end of the mounting chamber away from the piston rod forms a clearance hole for the extension and retraction of the pressure reducing valve core. The end of the pressure reducing valve core away from the limiting part is provided with a vent hole. One end of the vent hole is connected to the T-port, and the other end is connected to the clearance hole of the main valve body.

[0008] By adopting the above technical solution, the pressure-reducing valve core and the clearance hole of the mounting chamber form a closed space with variable volume. When the pressure-reducing valve core moves axially with the piston rod, or moves axially due to changes in oil pressure at port P, the volume of the closed space formed between the pressure-reducing valve core and the clearance hole changes. During this process, the oil in the closed space formed between the pressure-reducing valve core and the clearance hole flows into or out of the port T area through the drain hole, allowing the pressure-reducing valve core to move axially smoothly. Since the drain hole on the pressure-reducing valve core replaces the hole on the main valve body, it reduces oil leakage from the main valve body, which helps to enhance the reliability of the system.

[0009] Optionally, the pressure-reducing relief valve for the pilot handle further includes two valve sleeve assemblies, each corresponding to one of the two valve core assemblies. The valve sleeve assemblies are installed inside the mounting chamber. Each valve sleeve assembly includes a pressure-reducing valve sleeve, an inner limiting sleeve, and an outer limiting sleeve arranged sequentially along the axial direction. The outer limiting sleeve is located at the mounting port of the mounting chamber. The piston rod passes through and is connected to the outer limiting sleeve. The spring seat, return spring, and pressure-reducing spring are all located inside the inner limiting sleeve. The pressure-reducing valve sleeve and the pressure-reducing valve core are in clearance fit. The inner limiting sleeve has a T-hole that communicates with the T-port. The pressure-reducing valve sleeve has a P-hole and an A-hole that communicate with the P-port and the A-hole, respectively.

[0010] By adopting the above technical solution, the clearance fit between the pressure reducing valve sleeve and the pressure reducing valve core replaces the clearance fit between the main valve body and the pressure reducing valve core, making the hole that mates with the pressure reducing valve core easier to process.

[0011] Optionally, the outer peripheral surface of the pressure reducing valve core is provided with several pressure equalizing grooves; a sealing plug is provided at one end of the vent hole near the clearance hole; the pressure reducing valve core is provided with several radial connecting holes communicating with the closed end portion of the vent hole; the pressure reducing valve sleeve is provided with several connecting holes, the connecting holes are inclined relative to the center line of the pressure reducing valve sleeve, one end of the connecting hole is connected to the clearance hole, and the other end is connected to the inner hole of the pressure reducing valve sleeve.

[0012] By adopting the above technical solution, the sealing plug seals one end of the drain hole. When the pressure reducing valve core moves axially, the pressure reducing valve core and the oil in the clearance hole are drawn in or discharged through the drain hole, the pressure equalization groove and the connecting hole. During the process of the oil passing through the pressure equalization groove, it can play a lubricating role on the axial movement of the pressure reducing valve core.

[0013] Optionally, the sealing plug is installed by a threaded connection, and the center line of the radial connecting hole and the center of the pressure reducing valve core are straight lines in opposite planes. The liquid entering the drain hole from the radial connecting hole can form a swirling flow, and the direction of the swirling flow is the same as the direction of the sealing plug locking.

[0014] By adopting the above technical solution, the oil enters the drain hole from the radial connection hole and forms a swirling flow in the drain hole. The direction of the swirling flow is consistent with the locking direction of the sealing plug, which can prevent the sealing plug from loosening.

[0015] Optionally, the size of the opening of the connecting hole that connects to the inner hole of the pressure reducing valve sleeve along the center line of the pressure reducing valve sleeve is greater than or equal to the minimum distance between two adjacent pressure equalizing grooves.

[0016] By adopting the above technical solution, the dimension of the connecting hole along the axial direction of the pressure reducing valve sleeve is greater than the minimum distance between two adjacent pressure equalizing grooves, so that the connecting hole can be connected to at least one pressure equalizing groove during the axial movement of the pressure reducing valve core, thereby ensuring that the connecting hole and the pressure relief hole always remain connected.

[0017] Optionally, at least two connecting holes are provided, wherein the axial positions of the two connecting holes near the opening of the pressure reducing valve core are staggered from each other, and the total range is greater than the minimum distance between two adjacent pressure equalizing grooves.

[0018] By adopting the above technical solution, the total axial distribution range of the two connecting holes is greater than the minimum distance between two adjacent pressure equalization grooves, which enables the connecting holes to meet the communication state with the pressure relief holes with a smaller diameter.

[0019] Optionally, the inner wall of the pressure reducing valve sleeve is provided with an oil guiding slit, the two ends of the oil guiding slit have inner end faces, and the oil guiding slit communicates with the connecting hole.

[0020] By adopting the above technical solution, the connecting hole and the pressure relief hole are indirectly connected through the guide oil gap, which can ensure the reliability of the connection between the connecting hole and the pressure relief hole. End walls are provided at both ends of the guide oil gap to reduce oil leakage from the mating clearance between the pressure reducing valve core and the pressure reducing valve sleeve.

[0021] Optionally, the pressure reducing valve sleeve is provided with three spaced-apart sealing rings along the axial direction. The middle sealing ring is used to separate the P-port through hole and the A-port through hole. The outer circumference of the pressure reducing valve sleeve is distributed in a stepped axial shape corresponding to the three sealing rings, and gradually decreases in size away from the inner limiting sleeve. The part of the pressure reducing valve sleeve that mates with the middle sealing ring is a conical surface, and the part of the pressure reducing valve sleeve that mates with the sealing rings at both ends is a cylindrical surface. The inner wall of the mounting chamber is distributed in a stepped hole shape with the three sealing rings. The inner wall of the mounting chamber is distributed in a stepped hole shape with the middle sealing ring, and the part of the inner wall of the mounting chamber that mates with the sealing rings at both ends is a conical surface.

[0022] By adopting the above technical solution, the P-port and A-port through holes of the pressure reducing valve sleeve are separated and sealed using three sealing rings. During installation, the outer circumferential surface of the pressure reducing valve sleeve mates with the inner wall of the installation chamber for positioning. Since the positions of the outer circumferential surface of the pressure reducing valve sleeve and the inner wall of the installation chamber corresponding to the middle sealing ring are set as conical surfaces, when the outer limiting sleeve axially presses against the pressure reducing valve sleeve through the inner limiting sleeve, it ensures alignment between the pressure reducing valve sleeve and the installation chamber, thereby maintaining the overall concentricity of the valve sleeve assembly and the valve core assembly. The cylindrical surfaces of the sealing rings at both ends of the pressure reducing valve sleeve and the installation chamber ensure reliable frictional damping over a long range within the installation chamber, thus contributing to the reliability of the pressure reducing valve sleeve. Furthermore, the conical surface fit between the pressure reducing valve sleeve and the installation chamber enhances the isolation effect between the P-port and A-port.

[0023] Optionally, an elastic washer is provided between the inner limiting sleeve and the pressure reducing valve sleeve.

[0024] By adopting the above technical solution, when there is a deviation between the actual installation position of the outer limit sleeve and the ideal installation position, the elastic deformation of the elastic washer located between the inner limit sleeve and the pressure reducing valve core can compensate for the deviation in the installation position of the outer limit sleeve, so that the conical surface of the pressure reducing valve core and the conical surface of the inner wall of the installation cavity maintain a reliable tight fit, thereby further ensuring the alignment effect of the valve core assembly and the valve sleeve assembly.

[0025] In summary, this application includes at least one of the following beneficial technical effects: The drain hole on the pressure reducing valve core replaces the hole on the main valve body, which can reduce the leakage of oil in the main valve body and help enhance the reliability of the system.

[0026] The sealing plug seals one end of the drain hole. When the pressure reducing valve core moves axially, the pressure reducing valve core and the oil in the clearance hole are drawn in or discharged through the drain hole, the pressure equalization groove and the connecting hole. During the process of the oil passing through the pressure equalization groove, it can play a lubricating role on the axial movement of the pressure reducing valve core. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a pressure-reducing relief valve used for a pilot handle in the prior art.

[0028] Figure 2 This is a schematic diagram of the pressure-reducing relief valve used for the pilot handle in Example 1.

[0029] Figure 3 This is a schematic diagram of the pressure reducing valve core and pressure reducing valve sleeve in Example 1.

[0030] Figure 4 This is a schematic diagram of the pressure reducing valve core and pressure reducing valve sleeve in Example 2.

[0031] Figure 5 This is a schematic diagram of the pressure reducing valve core and pressure reducing valve sleeve in Example 3.

[0032] Figure 6 This is a schematic diagram of the cross-section of the pressure reducing valve core in Example 3.

[0033] Figure 7 This is a schematic diagram of the pressure reducing valve core and pressure reducing valve sleeve in Example 4.

[0034] Figure 8 This is a schematic diagram of the pressure reducing valve core and pressure reducing valve sleeve in Example 5.

[0035] Explanation of reference numerals in the attached figures: 1. Main valve body; 11. Mounting chamber; 111. Clearance hole; 12. P port; 13. A port; 14. T port; 15. Mounting port; 2. Valve core assembly; 3. Valve sleeve assembly; 21. Pressure reducing valve core; 211. Limiting part; 212. First switching part; 213. Second switching part; 214. Pressure equalizing groove; 215. Drain hole; 2151. Radial hole; 2152. Axial hole; 216. Radial connecting hole; 22. Piston rod; 221. Receiving hole; 222. Limiting flange; 2 3. Spring seat; 231. Positioning groove; 24. Return spring; 25. Pressure reducing spring; 27. Limiting clip; 271. Through hole; 2711. Snap-fit ​​area; 2712. Through-feed area; 28. Sealing plug; 31. Pressure reducing valve sleeve; 312. P-port through hole; 313. A-port through hole; 314. Separating sealing ring; 315. Connecting hole; 316. Oil guide slit; 32. Inner limiting sleeve; 321. T-port through hole; 33. Outer limiting sleeve; 331. U-shaped sealing ring; 34. Elastic washer. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1-8 This application will be described in further detail. Example 1

[0037] This application discloses a pressure-reducing relief valve for a pilot handle. (Refer to...) Figure 2 and Figure 3The pressure relief valve for the pilot handle includes a main valve body 1, two valve core assemblies 2, and two valve sleeve assemblies 3. The two valve sleeve assemblies 3 correspond to the two valve core assemblies 2 respectively. The main valve body 1 is provided with two mounting chambers 11 for mounting the valve core assemblies 2 and the valve sleeve assemblies 3. The mounting chambers 11 are provided with a P port 12, an A port 13, and a T port 14. The A port 13 is located between the P port 12 and the T port 14. The valve core assembly 2 includes a pressure reducing valve core 21, a piston rod 22, a return spring 24, and a pressure reducing spring 25. The piston rod 22 and the pressure reducing valve core 21 are arranged coaxially in sequence and are both installed in the mounting chambers 11. The mounting chambers 11 are provided with a mounting port 15 for one end of the piston rod 22 to extend out. The pressure reducing spring 25 is sleeved on the pressure reducing valve core 21, and the return spring 24 is sleeved on the periphery of the pressure reducing spring 25. A spring seat 23 is provided between the return spring 24 and the piston rod 22, and the spring seat 23 is sleeved on the pressure reducing valve core 21.

[0038] The pressure reducing valve core 21 is provided with a limiting part 211, a first switching part 212, and a second switching part 213 in sequence along the axial direction. The limiting part 211 is located at the end of the pressure reducing valve core 21 near the piston rod 22. The first switching part 212 is located between the second switching part 213 and the limiting part 211. The diameter of the first switching part 212 is larger than the diameter of the second switching part 213. The first switching part 212 is used to switch on and off port A 13 and port T 14. The second switching part 213 is used to switch on and off port A 13 and port P 12. The second switching part 213 is provided with a plurality of pressure equalizing grooves 214 at equal intervals along the axial direction.

[0039] The piston rod 22 is provided with a receiving hole 221 for accommodating the limiting part 211. A limiting card 27 is provided between the spring seat 23 and the piston rod 22. The spring seat 23 is provided with a positioning groove 231 for positioning the limiting card 27. The pressure reducing valve core 21 is connected to the limiting card 27. The limiting card 27 is provided with a through hole 271 for the pressure reducing valve core 21 to pass through. The through hole 271 includes a snap-fit ​​area 2711 and a through area 2712. The area of ​​the through area 2712 is larger than the area of ​​the snap-fit ​​area 2711. The limiting part 211 passes through the through area 2712. The snap-fit ​​area 2711 of the through hole 271 snaps the limiting part 211 to prevent the limiting part 211 from coming out of the receiving hole 221.

[0040] When installing the pressure reducing valve core 21 onto the spring seat 23, the limiting portion 211 of the pressure reducing valve core 21 is first passed through the spring seat 23 and the limiting card 27 in sequence. When the limiting portion 211 passes through the limiting card 27, it first passes through the through-hole 271's through-area 2712, and then the limiting card 27 is radially moved so that the locking area 2711 of the limiting card 27 locks the limiting portion 211. After the limiting card 27 is placed into the positioning groove 231 of the spring seat 23, the limiting portion 211 can maintain its locked state with the locking area 2711 of the through-hole 271 when the pressure reducing valve core 21 and the spring seat 23 are positioned. In another embodiment, the through-hole 271 with the through-hole 2712 and the locking area 2711 can be directly provided on the spring seat 23.

[0041] The pressure-reducing spring 25 is sleeved on the pressure-reducing valve core 21 and is located between the limiting part 211 and the first switching part 212. One end of the pressure-reducing spring 25 abuts against the spring seat 23 and the other end abuts against the first switching part 212. The pressure-reducing spring 25 can force the limiting part 211 to abut against the spring seat 23. The end of the mounting chamber 11 away from the piston rod 22 forms a clearance hole 111 for the extension and retraction of the pressure-reducing valve core 21. The end of the pressure-reducing valve core 21 away from the limiting part 211 is provided with a drain hole 215. One end of the drain hole 215 is connected to the T port 14 and the other end is connected to the clearance hole 111 of the main valve body 1.

[0042] The vent hole 215 includes a radial hole 2151 and an axial hole 2152. The diameter of the axial hole 2152 is larger than that of the radial hole 2151. The axial distribution range of the axial hole 2152 covers the fitting range between the pressure reducing valve core 21 and the pressure reducing valve sleeve 31.

[0043] The valve sleeve assembly 3 is installed inside the installation chamber 11. The valve sleeve assembly 3 includes a pressure reducing valve sleeve 31, an inner limiting sleeve 32, and an outer limiting sleeve 33 arranged sequentially along the axial direction. The outer limiting sleeve 33 is located at the installation port 15 of the installation chamber 11. The piston rod 22 passes through and is connected to the outer limiting sleeve 33. A U-shaped sealing ring 331 is used to achieve a dynamic seal between the piston rod 22 and the outer limiting sleeve 33. A limiting flange 222 is provided at one end of the piston rod 22 near the spring seat 23. The limiting flange 222 can obstruct the piston rod. 22. The outer limiting sleeve 33 is disengaged, and the limiting flange 222 is located in the positioning groove 231. The spring seat 23, the return spring 24 and the pressure reducing spring 25 are all located inside the inner limiting sleeve 32. The pressure reducing valve sleeve 31 and the pressure reducing valve core 21 are in clearance fit. The inner limiting sleeve 32 is provided with a T-port through hole 321, which is connected to the T-port 14. The pressure reducing valve sleeve 31 is provided with a P-port through hole 312 and an A-port through hole 313. The P-port through hole 312 is connected to the P-port 12, and the A-port through hole 313 is connected to the A-port 13.

[0044] The pressure reducing valve sleeve 31 is provided with three spacer sealing rings 314 at axial intervals. The middle spacer sealing ring 314 is used to separate the P port through hole 312 and the A port through hole 313. The outer circumference of the pressure reducing valve sleeve 31 has a stepped axial distribution corresponding to the three spacer sealing rings 314, and gradually decreases in size away from the inner limit sleeve 32. The parts of the pressure reducing valve sleeve 31 that mate with each spacer sealing ring 314 are all cylindrical surfaces. The inner wall of the mounting chamber 11 has a stepped hole distribution corresponding to the three spacer sealing rings 314. The parts of the inner wall of the mounting chamber 11 that mate with each spacer sealing ring 314 are all cylindrical surfaces.

[0045] In this application, the pressure reducing valve sleeve 31 and the pressure reducing valve core 21 are key components of the pressure reducing relief valve. Both are made of steel and are machined using a Swiss-type lathe. The workpiece is then heat-treated to control the surface hardness between HV600 and 700. After heat treatment, the workpiece is honed to control the cylindricity of the workpiece to within 0.003 mm.

[0046] The implementation principle of a pressure-reducing relief valve for a pilot handle in this application embodiment is as follows: The pressure-reducing valve core 21 and the clearance hole 111 of the mounting chamber 11 form a closed space with variable volume. When the pressure-reducing valve core 21 moves axially with the piston rod 22, or moves axially due to changes in oil pressure at port P 12, the volume of the closed space formed between the pressure-reducing valve core 21 and the clearance hole 111 changes. During this process, the oil in the closed space formed between the pressure-reducing valve core 21 and the clearance hole 111 flows into or out of the port T 14 area through the drain hole 215, allowing the pressure-reducing valve core 21 to move axially smoothly. The drain hole 215 replaces the hole on the main valve body 1, which can reduce the possibility of oil leakage from the main valve body 1 and enhance the reliability of the system. Example 2

[0047] Reference Figure 4 The difference between this embodiment and Embodiment 1 is that, in this embodiment, the part of the pressure reducing valve sleeve 31 that mates with the middle separating sealing ring 314 is a conical surface, and the part of the pressure reducing valve sleeve 31 that mates with the separating sealing rings 314 at both ends is a cylindrical surface; the part of the inner wall of the mounting chamber 11 that mates with the middle separating sealing ring 314 is a conical surface, and the part of the inner wall of the mounting chamber 11 that mates with the separating sealing rings 314 at both ends is a cylindrical surface. Furthermore, in this embodiment, an elastic washer 34 is provided between the inner limiting sleeve 32 and the pressure reducing valve sleeve 31. The elastic washer 34 can be a metal spring washer or an elastic plastic washer.

[0048] The implementation principle of this embodiment is as follows: The P-port through hole 312 and A-port through hole 313 of the pressure reducing valve sleeve 31 are separated and sealed by three sealing rings. When the three separating sealing rings 314 are installed, the outer peripheral surface of the pressure reducing valve sleeve 31 is used to cooperate with the inner wall of the installation chamber 11 to achieve positioning. Since the position of the middle sealing ring corresponding to the outer peripheral surface of the pressure reducing valve sleeve 31 and the inner wall of the installation chamber 11 is set as a conical surface, when the outer limiting sleeve 33 is axially pressed against the pressure reducing valve sleeve 31 through the inner limiting sleeve 32, the pressure reducing valve sleeve 31 can be aligned with the installation chamber 11, thereby keeping the valve sleeve assembly 3 and the valve core assembly 2 as a whole aligned. The parts of the separating sealing rings 314 at both ends of the pressure reducing valve sleeve 31 and the installation chamber 11 are set as cylindrical surfaces, which can ensure that the separating sealing rings 314 at both ends can maintain reliable frictional damping effect over a long range in the installation chamber 11, thereby helping to ensure the stability of the pressure reducing valve sleeve 31. Furthermore, the tapered fit between the pressure reducing valve sleeve 31 and the mounting chamber 11 enhances the isolation effect between port P 12 and port A 13. Example 3

[0049] Reference Figure 5 and Figure 6 The difference between this embodiment and Embodiment 1 is that, in this embodiment, a sealing plug 28 is provided at the end of the drain hole 215 near the clearance hole 111. The sealing plug 28 is installed by a threaded connection. The pressure reducing valve core 21 has several radial connecting holes 216 that communicate with the closed end portion of the drain hole 215. The pressure reducing valve sleeve 31 has several connecting holes 315, which are inclined relative to the center line of the pressure reducing valve sleeve 31. One end of the connecting hole 315 communicates with the clearance hole 111, and the other end communicates with the inner hole of the pressure reducing valve sleeve 31. The angle between the center line of the connecting hole 315 and the center line of the pressure reducing valve sleeve 31 is between 30° and 45°.

[0050] The number of connecting holes 315 is set to an even number, specifically four in this embodiment. The connecting holes 315 are symmetrically arranged in pairs along the center line of the pressure reducing valve core 21. The opening of the connecting hole 315 connecting to the inner hole of the pressure reducing valve sleeve 31 has a dimension along the center line of the pressure reducing valve sleeve 31 that is greater than or equal to the minimum distance between two adjacent pressure equalizing grooves 214.

[0051] The radial connecting holes 216 are arranged in a circumferential array along the center line of the pressure reducing valve core 21. The center line of the radial connecting holes 216 and the center of the pressure reducing valve core 21 are skew lines. The liquid entering the drain hole 215 from the radial connecting holes 216 can form a swirling flow. The direction of the swirling flow is the same as the direction of locking the sealing plug 28, which is beneficial to the anti-loosening function of the sealing plug 28.

[0052] The implementation principle of this embodiment is as follows: the sealing plug 28 seals one end of the drain hole 215. When the pressure reducing valve core 21 moves axially, the oil in the pressure reducing valve core 21 and the clearance hole 111 is drawn in or discharged through the drain hole 215, the pressure equalizing groove 214, and the connecting hole 315. During the process of the oil passing through the pressure equalizing groove 214, it can lubricate the axial movement of the pressure reducing valve core 21. The dimension of the connecting hole 315 along the axial direction of the pressure reducing valve sleeve 31 is larger than the minimum distance between two adjacent pressure equalizing grooves 214, so that the connecting hole 315 can communicate with at least one pressure equalizing groove 214 during the axial movement of the pressure reducing valve core 21, thereby ensuring that the connecting hole 315 and the pressure relief hole always remain in a connected state. Example 4

[0053] Reference Figure 7 The difference between this embodiment and embodiment 3 is that in this embodiment, the inner wall of the pressure reducing valve sleeve 31 is provided with an oil guiding slit 316, the two ends of the oil guiding slit 316 have inner end faces, and the oil guiding slit 316 is connected to the connecting hole 315.

[0054] In this embodiment, the connecting hole 315 and the pressure relief hole are indirectly connected through a guide oil slit, which ensures the reliability of the connection between the connecting hole 315 and the pressure relief hole. End walls are provided at both ends of the guide oil slit to reduce oil leakage from the mating gap between the pressure reducing valve core 21 and the pressure reducing valve sleeve 31. Example 5

[0055] Reference Figure 8 The difference between this embodiment and embodiment 3 is that the axial positions of two adjacent connecting holes 315 near the opening of the pressure reducing valve core 21 are staggered, and the total distribution range is greater than the minimum distance between two adjacent pressure equalizing grooves 214.

[0056] In this embodiment, the total axial distribution range of the two connecting holes 315 is greater than the minimum distance between two adjacent pressure equalization grooves 214, which enables the connecting holes 315 to meet the communication state with the pressure relief hole with a smaller hole diameter.

[0057] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A pressure-reducing relief valve for a pilot handle, characterized in that: The system includes a main valve body (1) and two valve core assemblies (2). The main valve body (1) has two mounting chambers (11) for mounting the valve core assemblies (2). The mounting chambers (11) have a P port (12), an A port (13), and a T port (14). The A port (13) is located between the P port (12) and the T port (14). The valve core assembly (2) includes a pressure reducing valve core (21), a piston rod (22), a return spring (24), and a pressure reducing spring (25). The piston rod (22) and the pressure reducing valve core (21) are arranged coaxially in sequence and are both installed in the mounting chambers (11). The mounting chambers (11) have mounting ports (15) for one end of the piston rod (22) to extend out. The pressure reducing spring (25) is sleeved on the pressure reducing valve core (21), and the return spring (24) is sleeved around the pressure reducing spring (25). The return spring (24) and the piston rod (22) are connected. A spring seat (23) is provided between the piston rod (22) and the piston rod (22). The spring seat (23) is sleeved on the pressure reducing valve core (21). The pressure reducing valve core (21) has a limiting part (211) at one end near the piston rod (22). The piston rod (22) has a receiving hole (221) for accommodating the limiting part (211). The spring seat (23) can prevent the limiting part (211) from coming out of the receiving hole (221). The pressure reducing spring (25) can force the limiting part (211) to abut against the spring seat (23). The mounting chamber (11) forms a clearance hole (111) at one end away from the piston rod (22) for the expansion and contraction of the pressure reducing valve core (21). The pressure reducing valve core (21) has a drain hole (215) at one end away from the limiting part (211). One end of the drain hole (215) is connected to the T port (14), and the other end is connected to the clearance hole (111) of the main valve body (1).

2. A pressure-reducing relief valve for a pilot handle according to claim 1, characterized in that: It also includes two valve sleeve assemblies (3), which are respectively arranged corresponding to the two valve core assemblies (2). The valve sleeve assemblies (3) are installed inside the mounting chamber (11). The valve sleeve assembly (3) includes a pressure reducing valve sleeve (31), an inner limiting sleeve (32), and an outer limiting sleeve (33) arranged sequentially along the axial direction. The outer limiting sleeve (33) is located at the mounting port (15) of the mounting chamber (11). The piston rod (22) is connected to the outer limiting sleeve (33). The spring seat (23) The reset spring (24) and the pressure reducing spring (25) are both located inside the inner limiting sleeve (32). The pressure reducing valve sleeve (31) is clearance-fitted with the pressure reducing valve core (21). The inner limiting sleeve (32) is provided with a T-hole (321), which is connected to the T-hole (14). The pressure reducing valve sleeve (31) is provided with a P-hole (312) and an A-hole (313). The P-hole (312) is connected to the P-hole (12), and the A-hole (313) is connected to the A-hole (13).

3. A pressure-reducing relief valve for a pilot handle according to claim 2, characterized in that: The outer circumferential surface of the pressure reducing valve core (21) is provided with several pressure equalizing grooves (214); the end of the vent hole (215) near the clearance hole (111) is provided with a sealing plug (28); the pressure reducing valve core (21) is provided with several radial connecting holes (216) that communicate with the closed end of the vent hole (215); the pressure reducing valve sleeve (31) has several connecting holes (315), the connecting holes (315) are inclined relative to the center line of the pressure reducing valve sleeve (31), one end of the connecting hole (315) communicates with the clearance hole (111), and the other end communicates with the inner hole of the pressure reducing valve sleeve (31).

4. A pressure-reducing relief valve for a pilot handle according to claim 3, characterized in that: The sealing plug (28) is installed by a threaded connection. The center line of the radial connection hole (216) and the center of the pressure reducing valve core (21) are skew lines. The liquid entering the drain hole (215) from the radial connection hole (216) can form a swirling flow. The direction of the swirling flow is the same as the direction of locking the sealing plug (28).

5. A pressure-reducing relief valve for a pilot handle according to claim 3, characterized in that: The opening of the connecting hole (315) connecting the inner hole of the pressure reducing valve sleeve (31) has a dimension along the center line of the pressure reducing valve sleeve (31) that is greater than or equal to the minimum distance between two adjacent pressure equalizing grooves (214).

6. A pressure-reducing relief valve for a pilot handle according to claim 3, characterized in that: At least two connecting holes (315) are provided, wherein the axial positions of the two connecting holes (315) near the opening of the pressure reducing valve core (21) are staggered from each other, and the total range is greater than the minimum distance between two adjacent pressure equalizing grooves (214).

7. A pressure-reducing relief valve for a pilot handle according to claim 3, characterized in that: The inner wall of the pressure reducing valve sleeve (31) is provided with an oil guiding slit (316), and the two ends of the oil guiding slit (316) have inner end faces. The oil guiding slit (316) is connected to the connecting hole (315).

8. A pressure-reducing relief valve for a pilot handle according to claim 2, characterized in that: The pressure reducing valve sleeve (31) is provided with three spacer sealing rings (314) spaced axially. The middle spacer sealing ring (314) is used to separate the P-port through hole (312) and the A-port through hole (313). The outer circumference of the pressure reducing valve sleeve (31) is distributed in a stepped axial shape corresponding to the three spacer sealing rings (314), and gradually decreases in size away from the inner limiting sleeve (32). The pressure reducing valve sleeve (31) and the middle spacer sealing ring (314) are matched. The mating part is set as a conical surface, and the part of the pressure reducing valve sleeve (31) that mates with the two end separator sealing rings (314) is set as a cylindrical surface; the part of the inner wall of the mounting chamber (11) that mates with the three separator sealing rings (314) is distributed in a stepped hole shape, the part of the inner wall of the mounting chamber (11) that mates with the middle separator sealing ring (314) is set as a conical surface, and the part of the inner wall of the mounting chamber (11) that mates with the two end separator sealing rings (314) is set as a cylindrical surface.

9. A pressure-reducing relief valve for a pilot handle according to claim 8, characterized in that: An elastic washer (34) is provided between the inner limiting sleeve (32) and the pressure reducing valve sleeve (31).

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