An unloading valve with a built-in pilot type main valve core and application thereof

Abstract

The utility model relates to unloading valve technical field especially relates to a kind of inner-mounted pilot main valve core and the unloading valve of application thereof, main valve core includes: the pilot cavity is opened in main valve core inside, and first through-hole and second through-hole are opened to communicate pilot cavity;Control valve core is installed in pilot cavity, and third through-hole is opened to communicate first through-hole, control valve core moves towards the direction close to or away from first through-hole;Pilot valve sleeve is installed in pilot cavity, and one end is abutted with control valve core, and pilot port is opened in the side close to control valve core;Pilot valve core is installed in pilot valve sleeve, and abuts pilot port, moves towards the direction close to or away from first through-hole, and flow-through groove is opened along length direction in the outer wall of pilot valve core;Plug, it is installed in the side of main valve core away from control valve core, and fourth through-hole is opened in the center to communicate flow-through groove;Pilot spring is installed in pilot cavity, one end is abutted with pilot valve core, one end is abutted with plug.The utility model integrates inner-mounted pilot main valve core, improves space utilization and light weight level.

Description

Technical Field

[0001] This utility model relates to the field of unloading valve technology, and in particular to an unloading valve with an internally installed pilot-operated main valve core and its application. Background Technology

[0002] In hydraulic systems, unloading valves are key pressure control valves. Their core function is to automatically guide the hydraulic oil output from the press's buffer oil tank or other high-pressure oil tank back to the oil tank at extremely low pressure when the system pressure reaches a preset value. This allows the press's buffer oil tank or other high-pressure oil tank to operate in a near-zero load unloading state. To achieve precise control of high-flow, high-pressure oil circuits, pilot-operated unloading valves are widely used. They typically consist of a two-stage structure: a pilot valve and a main valve. The pilot valve senses the system pressure and sends a control signal, while the main valve switches the high-flow oil circuit on and off according to this signal.

[0003] Currently, the mainstream design of pilot-operated unloading valves on the market usually adopts a split structure. Since the pilot valve is an independent external component, it requires additional installation interfaces, connecting channels, and fasteners, which increases the size and weight of the entire unloading valve. This is not conducive to the hydraulic system, especially for compact designs of mobile devices or integrated hydraulic modules with strict space layout requirements. Furthermore, the connection between the pilot valve and the main valve body requires precision machining and assembly, which increases the complexity of manufacturing. The increased number of sealing surfaces at the connection means that failure of any connection surface or sealing ring may lead to leakage in the pilot control oil circuit, thereby causing the unloading valve to malfunction and affecting the reliability of the entire hydraulic system.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0005] This utility model provides an unloading valve with an internally mounted pilot-operated main valve core and its application. It adopts a structure that integrates the pilot valve core, control valve core, control valve sleeve, pilot valve sleeve and pilot spring into the pilot cavity of the main valve core to form a highly compact and responsive unloading valve unit.

[0006] This utility model provides an internally mounted pilot-operated main valve core, comprising: The main valve core has a pilot cavity inside, and a first through hole and a second through hole connecting the pilot cavity; A control valve core is installed in the pilot cavity, with a third through hole in the center connecting to the first through hole. The control valve core moves toward or away from the first through hole. A pilot valve sleeve is installed in the pilot cavity, with one end abutting against the control valve core, and a pilot port is opened on the side close to the control valve core; A pilot valve core is installed inside the pilot valve sleeve, abuts against the pilot port, and moves toward or away from the first through hole. A flow groove is formed on the outer wall of the pilot valve core along the length direction. A plug is installed on the side of the main valve core away from the control valve core, with a fourth through hole in the center connecting to the flow groove; A pilot spring is installed inside the pilot cavity, with one end abutting against the pilot valve core and the other end abutting against the plug.

[0007] Furthermore, a control valve sleeve is also provided inside the pilot cavity, which is sleeved on the control valve core, with one end abutting against the pilot valve sleeve and the other end abutting against the main valve core.

[0008] Furthermore, a fifth through hole is provided on the control valve sleeve, connecting the second through hole and the internal space of the control valve sleeve.

[0009] Furthermore, the pilot valve core is configured with a variable diameter at one end facing the pilot port.

[0010] Furthermore, a first sealing assembly is provided between the pilot valve sleeve and the main valve core.

[0011] Furthermore, a second sealing group is provided between the control valve core and the control valve sleeve, and a third sealing group is provided between the control valve sleeve and the main valve core.

[0012] This utility model also provides an unloading valve, comprising: The main valve assembly has a preload pressure oil inlet, a return oil inlet, and a high-pressure oil inlet, and has a main valve chamber inside, which is connected to the preload pressure oil inlet, the return oil inlet, and the high-pressure oil inlet; A main valve sleeve is disposed in the main valve chamber and extends along the preload pressure oil inlet to the return oil outlet. A sixth through hole is provided on the main valve sleeve. The main valve core is disposed inside the main valve sleeve and moves toward or away from the return oil port. The first through hole is connected to the return oil port, the second through hole is connected to the high-pressure oil inlet, and the fourth through hole is connected to the preload pressure oil inlet. The main valve spring is installed inside the main valve sleeve, with one end abutting against the main valve core and the other end abutting against the main valve assembly.

[0013] Furthermore, the main valve assembly includes a main valve end cap and a main valve body. The main valve body has a main valve chamber inside. The main valve end cap has a preload pressure oil inlet. The main valve body has a return oil inlet and a high-pressure oil inlet.

[0014] Furthermore, a check valve is provided on the main valve end cover, which connects to the preload pressure oil inlet.

[0015] Furthermore, a fourth sealing group is provided between the main valve core and the main valve sleeve, and a fifth sealing group is provided between the main valve sleeve and the main valve body.

[0016] The following technical effects can be achieved through the technical solution of this utility model: By integrating pilot control components such as pilot valve core, control valve core, pilot valve sleeve, and spring into the main valve core, a highly integrated functional unit is formed. This eliminates the need for a separate external pilot valve block, complex installation interfaces, and lengthy external connection channels, making the entire unloading valve structure extremely compact and significantly reducing its size and weight. This is beneficial for its application in mobile equipment with limited space or in highly integrated hydraulic modules. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the pilot-operated main valve core in an embodiment of the present utility model; Figure 2 This is a top view of the pilot-operated main valve core installed in an embodiment of the present invention; Figure 3 for Figure 2 Sectional view at point AA; Figure 4 This is a schematic diagram of the pilot valve core in an embodiment of the present invention; Figure 5 This is a schematic diagram of the unloading valve in an embodiment of the present invention; Figure 6 This is a top view of the unloading valve in an embodiment of this utility model; Figure 7 for Figure 6 Sectional view at point BB; Figure 8 This is a schematic diagram of the main valve sleeve in an embodiment of the present invention.

[0019] Reference numerals: 1. Main valve core; 101. Pilot chamber; 102. First through hole; 103. Second through hole; 2. Control valve core; 201. Third through hole; 3. Pilot valve sleeve; 301. Pilot port; 302. First sealing group; 4. Pilot valve core; 401. Flow groove; 5. Plug; 501. Fourth through hole; 6. Pilot spring; 7. Control valve sleeve; 701. Fifth through hole; 702. Second sealing group; 703. Third sealing group; 8. Main valve assembly; 801. Preload pressure oil inlet; 802. Oil return port; 803. High pressure oil inlet; 804. Main valve chamber; 805. Main valve end cap; 8051. Check valve; 806. Main valve body; 9. Main valve sleeve; 901. Sixth through hole; 902. Fourth sealing group; 903. Fifth sealing group; 10. Main valve spring. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] This utility model provides a method such as Figures 1 to 4 The internally mounted pilot-operated main valve core shown includes: The main valve core 1 has a pilot cavity 101 inside, and a first through hole 102 and a second through hole 103 connecting the pilot cavity 101. The control valve core 2 is installed in the pilot cavity 101, with a third through hole 201 in the center connecting to the first through hole 102. The control valve core 2 moves toward or away from the first through hole 102. Pilot valve sleeve 3 is installed in pilot cavity 101, one end of which abuts against control valve core 2, and pilot port 301 is opened on the side near control valve core 2; The pilot valve core 4 is installed inside the pilot valve sleeve 3, abutting against the pilot port 301, and moves toward or away from the first through hole 102. A flow groove 401 is formed on the outer wall of the pilot valve core 4 along the length direction. The plug 5 is installed on the side of the main valve core 1 away from the control valve core 2, and a fourth through hole 501 is opened in the center to connect the flow groove 401; The pilot spring 6 is installed in the pilot cavity 101, with one end abutting against the pilot valve core 4 and the other end abutting against the plug 5.

[0023] The main valve core 1 is a cylindrical or multi-stage cylindrical rod-shaped part with a pilot cavity 101 machined axially inside. One end of the pilot cavity 101 is open to accommodate the plug 5. An axial through hole and a radial through hole are machined on the main valve core 1, which are defined as the first through hole 102 and the second through hole 103, respectively. Both the first through hole 102 and the second through hole 103 are connected to the pilot cavity 101. The second through hole 103 is used to connect to the external control input.

[0024] The control valve core 2 is installed in the pilot cavity 101. The control valve core 2 is generally a variable diameter cylinder with a third through hole 201 machined through its center along the axial direction. One end of the third through hole 201 is connected to the area where the first through hole 102 is located. The outer diameter of the control valve core 2 matches the inner diameter of the pilot cavity 101, so that the control valve core 2 can slide axially in the pilot cavity 101. The direction of movement is towards or away from the first through hole 102, and is controlled by the pressure distribution in the pilot cavity 101.

[0025] Pilot valve sleeve 3 is also installed in pilot cavity 101. Pilot valve sleeve 3 is a sleeve-shaped part with a smaller pilot port 301 at one end and a larger opening at the other end. Pilot port 301 is the passage for pilot control oil to flow into the third through hole 201 of control valve core 2. Pilot valve core 4 is installed in the internal cavity of pilot valve sleeve 3. Pilot valve core 4 is a rod-shaped part. The end near pilot port 301 is designed with a conical surface, spherical surface or other sealing surface to abut and seal or open pilot port 301. Pilot valve core 4 can also move along the pilot valve sleeve 3. The inner cavity slides axially, and the direction of movement is towards or away from the first through hole 102. On the cylindrical outer wall of the pilot valve core 4, one or more flow grooves 401 are machined along its length. The flow grooves 401 can be straight grooves, spiral grooves or irregular grooves. Their function is to form a bypass channel between the pilot valve core 4 and the inner wall of the pilot valve sleeve 3, allowing fluid to pass through. When the pilot valve core 4 is in a position away from and with the pilot port 301 open, the fluid can flow from the end of the pilot valve core 4 away from the pilot port 301 to the pilot port 301 through the flow grooves 401.

[0026] The plug 5 can be installed on the main valve core 1 at the end away from the control valve core 2 by means of threaded connection, interference fit or snap ring fixation, etc., to construct the pilot chamber 101, thereby fixing the pilot valve sleeve 3. The plug 5 has a fourth through hole 501 machined in the center. The fourth through hole 501 is connected to the area where the flow groove 401 is located on the pilot valve core 4, thereby leading the fluid pressure at one end of the pilot valve core 4 to the pilot port 301. Usually, the fluid pressure connected to the preload pressure oil inlet 801 is directed to the pilot port 301.

[0027] The pilot spring 6 is disposed in the pilot cavity 101. One end of the pilot spring 6 abuts against the end of the pilot valve core 4 away from the pilot port 301. Preferably, the pilot valve core 4 may also have a spring receiving hole to accommodate one end of the pilot spring 6, and the other end abuts against the inner side of the plug 5, thereby guiding the compression and rebound direction of the pilot spring 6 without causing deviation. The pilot spring 6 is a compression spring, and the preload is the main source of the preset pilot pressure, always applying a force to the pilot valve core 4 that causes the pilot valve core 4 to press itself against the pilot port 301.

[0028] Brief description of working principle: Preload pressure is introduced above the main valve core 1, that is, above the pilot valve core 4, at the location of the fourth through hole 501. Then, overload pressure is input from the second through hole 103 of the main valve core 1 and applied to the variable diameter section of the control valve core 2. When the overload pressure on the control valve core 2 is greater than the preset pressure value, the control valve core 2 moves upward toward the pilot valve core 4 and pushes the pilot valve core 4 toward the plug 5. At this time, the pilot valve core 4 moves away from the pilot port 301 and opens the pilot port 301. The preset pressure can then flow into the flow groove 401 of the pilot valve core 4 through the fourth through hole 501 of the plug 5, and into the third through hole 201 of the control valve core 2 through the pilot port 301. Finally, it flows out through the first through hole 102 of the main valve core 1. The preload pressure above the main valve core 1 is reduced or even reduced to zero.

[0029] In some embodiments of this utility model, such as Figure 3 As shown, a control valve sleeve 7 is also provided inside the pilot cavity 101, which is fitted onto the control valve core 2. One end abuts against the pilot valve sleeve 3, and the other end abuts against the main valve core 1. The control valve sleeve 7 is an independent sleeve part. Its outer wall fits with the inner wall of the pilot cavity 101, and its inner wall fits with the outer wall of the control valve core 2. One end of the control valve sleeve 7 directly abuts against the end of the pilot valve sleeve 3 or is positioned by a stepped structure. The other end of the control valve sleeve 7 abuts against the end face of the pilot cavity 101 inside the main valve core 1. The control valve core 2 is installed inside the control valve sleeve 7 and fits with the inner hole of the control valve sleeve 7. It moves axially along the main valve core 1. The control valve sleeve 7 and the pilot valve sleeve 3 are fixed in the inner cavity of the main valve core 1 by the plug 5 and will not move. The control valve core 2 and the pilot valve core 4 move together in the same direction.

[0030] In some embodiments of this utility model, such as Figure 3As shown, a fifth through hole 701 is provided on the control valve sleeve 7, connecting the second through hole 103 and the internal space of the control valve sleeve 7. One end of the fifth through hole 701 is connected to the second through hole 103, and the other end is connected to the space between the inner wall of the control valve sleeve 7 and the outer wall of the control valve core 2. The fifth through hole 701 serves as a channel for supplying pressure oil from the outside to the internal control pressure chamber through the second through hole 103. At the same time, a through hole is also provided on the control valve sleeve 7 at the position corresponding to the third through hole 201 of the control valve core 2 to connect the third through hole 201 and the first through hole 102 of the main valve core 1.

[0031] In some embodiments of this utility model, such as Figure 3 and Figure 4 As shown, the pilot valve core 4 has a variable diameter end facing the pilot port 301. The end can be designed as a tapered head, ball head, etc. with a gradually decreasing diameter. In this embodiment, a combination of conical and cylindrical surfaces is used. The end closer to the pilot port 301 has a smaller diameter, and the end further away from the pilot port 301 has a larger diameter. The conical surface abuts against the pilot port 301 to achieve line contact or narrow band contact, thereby cutting off or connecting the oil circuit. This allows for a significant change in flow area with minimal axial displacement, resulting in a rapid response.

[0032] In some embodiments of this utility model, such as Figure 3 As shown, a first sealing group 302 is provided between the pilot valve sleeve 3 and the main valve core 1. It may include one or more O-rings, which are installed in the groove on the outer wall of the pilot valve sleeve 3 to prevent the pressure fluid outside the pilot valve sleeve 3 from leaking between the pilot valve sleeve 3 and the control valve core 2, such as the preload pressure fluid from the fourth through hole 501 on the plug 5.

[0033] In some embodiments of this utility model, such as Figure 3 As shown, a second sealing group 702 is provided between the control valve core 2 and the control valve sleeve 7, and a third sealing group 703 is provided between the control valve sleeve 7 and the main valve core 1.

[0034] The second sealing assembly 702 typically includes a sealing ring installed in a groove on the outer wall of the control valve core 2 to seal the sliding surface of the control valve core 2, preventing fluid in the fifth through hole 701 of the control valve sleeve 7 from leaking toward the first through hole 102 or the pilot valve core 4, and ensuring that the control pressure is effectively applied to the side wall of the control valve core 2.

[0035] Similarly, a third sealing assembly 703 is provided between the inner wall of the control valve sleeve 7 and the main valve core 1, including a sealing ring installed in the groove of the outer wall of the control valve sleeve 7, to prevent fluid from the second through hole 103 from leaking from the mating gap between the control valve sleeve 7 and the main valve core 1, and to ensure that all control fluid enters and contacts the control valve core 2 through the fifth through hole 701.

[0036] This utility model also provides a method such as Figures 5 to 8 The unloading valve shown includes: The main valve assembly 8 has a preload pressure oil inlet 801, a return oil inlet 802 and a high pressure oil inlet 803, and has a main valve chamber 804 inside, which is connected to the preload pressure oil inlet 801, the return oil inlet 802 and the high pressure oil inlet 803. The main valve sleeve 9 is located in the main valve chamber 804 and extends along the preload pressure oil inlet 801 to the return oil inlet 802. A sixth through hole 901 is opened on the main valve sleeve 9. The main valve core 1 is located inside the main valve sleeve 9 and moves toward or away from the return oil port 802. The first through hole 102 is connected to the return oil port 802, the second through hole 103 is connected to the high pressure oil inlet 803, and the fourth through hole 501 is connected to the preload pressure oil inlet 801. The main valve spring 10 is installed inside the main valve sleeve 9, with one end abutting against the main valve core 1 and the other end abutting against the main valve assembly 8.

[0037] The main valve assembly 8 forms the valve body frame of the unloading valve, and has an axially extending cylindrical main valve cavity 804 machined inside. Three main oil ports are provided on the outer wall of the main valve assembly 8: a preload pressure oil inlet 801, a return oil port 802, and a high-pressure oil inlet 803. The preload pressure oil inlet 801 and the return oil port 802 are preferably arranged opposite each other along the axial direction of the main valve cavity 804, while the high-pressure oil inlet 803 is connected to the main valve cavity 804 from the side. The main valve cavity 804 is connected to these three oil ports, forming the main channel for oil flow. The preload pressure oil inlet 801 and the return oil port 802 can also be arranged relative to the main valve sleeve 9, for example, around the main valve end cover 805.

[0038] The main valve sleeve 9 is a sleeve-shaped part, which is fixedly installed in the main valve cavity 804 by press fitting or other means. The axial length of the main valve sleeve 9 covers the entire main valve cavity 804 from the preload pressure oil inlet 801 area to the return oil inlet 802 area. The inner hole is a smooth cylindrical surface, which serves as a sliding guide pair for the main valve core 1. Several sixth through holes 901 are opened on the side wall of the main valve sleeve 9, which correspond to the high pressure oil inlet 803, so that the oil entering from the high pressure oil inlet 803 can flow into the interior of the main valve sleeve 9 through the sixth through holes 901.

[0039] The internally mounted pilot-operated main valve core 1 is slidably disposed within the inner bore of the main valve sleeve 9 as an integral module. The main valve core 1 can reciprocate along the axis within the main valve sleeve 9, moving towards or away from the return port 802. The first through hole 102 on the main valve core 1 is normally open to the return port 802 of the unloading valve for oil drainage. The second through hole 103 on the main valve core 1 is connected to the sixth through hole 901 on the main valve sleeve 9 and the high-pressure oil inlet 803 of the unloading valve, thereby receiving pressure from the system load, which is also the high-pressure pressure that needs to be unloaded. The fourth through hole 501 on the end plug 5 of the main valve core 1 is connected to the preload pressure oil inlet 801 of the unloading valve, introducing the system's preload pressure into the spring side of the pilot valve core 4.

[0040] The main valve spring 10 is installed inside the main valve sleeve 9, located at the end of the main valve core 1 near the preload pressure oil inlet 801. One end of the main valve spring 10 abuts against the corresponding end face of the main valve core 1, and the other end abuts against the corresponding part of the main valve assembly 8. The main valve spring 10 is a compression spring, and the preload force provides the initial reset force for the main valve core 1, so that the main valve core 1 keeps blocking the oil passage between the return oil port 802 and the high pressure oil inlet 803 when the unloading pressure is not reached.

[0041] Brief description of working principle: During normal operation, the preset pressure enters through the preload pressure oil inlet 801. If the overload pressure at the high-pressure oil inlet 803 does not reach the set value, the pilot-operated main valve core 1, built into the main valve assembly 8, remains stationary in its initial position. When the overload pressure at the high-pressure oil inlet 803 increases and exceeds the preset pressure, the control valve core 2 is pushed, causing the pilot valve core 4 to move towards the plug 5, i.e., towards the preload pressure oil inlet 801. At this time, the pilot port 301 is opened, and the preload pressure flows from the preload pressure oil inlet 801 through the fourth through hole 501 of the plug 5, the flow groove 401 of the pilot valve core 4, the pilot port 301, the third through hole 201 of the control valve core 2, the control valve sleeve 7, and the first through hole 102 of the main valve core 1, finally reaching the return port 802. At this time, due to the preload pressure oil inlet 801... When the preload pressure fluid flows at point 1, the preload pressure decreases, and the pressure on the main valve core 1 at the high-pressure oil inlet 803 remains unchanged. Therefore, the main valve core 1 is pushed to move closer to the preload pressure oil inlet 801, compressing the main valve spring 10, thereby connecting the high-pressure oil inlet 803 and the return oil port 802. That is, the unloading valve is opened, and the main valve port formed by the passage between the high-pressure oil inlet 803 and the return oil port 802 is opened, thereby realizing system unloading and draining the high-pressure oil in the main valve chamber 804 from the return oil port 802 into the oil tank. When the pressure at the high-pressure oil inlet 803 drops, the main valve core 1 is reset under the action of the main valve spring 10 and the preload oil pressure continuously input in the preload pressure oil inlet 801, blocking the high-pressure oil inlet 803 and the return oil port 802. The pilot valve core 4 and the control valve core 2 are also reset under the push of the pilot spring 6, sealing the pilot port 301.

[0042] In some embodiments of this utility model, such as Figure 7 As shown, the main valve assembly 8 includes a main valve end cover 805 and a main valve body 806. The main valve body 806 has a main valve chamber 804 inside. The main valve end cover 805 has a preload pressure oil inlet 801. The main valve body 806 has a return oil port 802 and a high-pressure oil inlet 803. The return oil port 802 and the preload pressure oil inlet 801 are arranged opposite to each other.

[0043] The main valve end cap 805 is fixedly installed at one end of the main valve body 806 by means of screws, bolts or threaded connections. The main valve body 806 is the main body part, and the main valve cavity 804 is machined inside. The high-pressure oil inlet 803 and the oil return port 802 are opened on the side wall of the main valve body 806. The main valve sleeve 9 is press-fitted into the main valve cavity 804 of the main valve body 806. The main valve end cap 805 is provided with a preload pressure oil inlet 801, and usually has a spring seat hole in the center for positioning one end of the main valve spring 10, thereby reducing the difficulty of deep hole machining of the main valve cavity 804. The main valve end cap 805 can be independently machined with the preload pressure oil inlet 801 and related complex flow channels, simplifying the structure of the main valve body 806 and facilitating assembly, debugging and maintenance. The main valve spring 10 and the main valve core 1 can be removed by simply removing the main valve end cap 805.

[0044] In some embodiments of this utility model, such as Figure 7 As shown, a check valve 8051 is provided on the main valve end cover 805, which is connected to the preload pressure oil inlet 801. After unloading by connecting to the external compressor buffer oil tank or high pressure oil tank through the high pressure oil inlet 803, oil can be replenished to the external compressor buffer oil tank or high pressure oil tank through the check valve 8051, the main valve chamber 804, and the sixth through hole 901, and finally from the high pressure oil inlet 803.

[0045] In some embodiments of this utility model, such as Figure 7 As shown, a fourth sealing group 902 is provided between the main valve core 1 and the main valve sleeve 9, and a fifth sealing group 903 is provided between the main valve sleeve 9 and the main valve body 806.

[0046] The fourth sealing group 902 is located between the inner hole of the main valve core 1 and the main valve sleeve 9. It usually includes several O-rings or stepped seals installed in the outer circular groove of the main valve core 1 to ensure that the pressure fluid at the high pressure oil inlet 803 does not flow into the main valve spring 10, or to prevent the pressure fluid at the main valve spring 10, i.e. the preload pressure oil inlet 801, from flowing into the high pressure oil inlet 803 and the return oil inlet 802.

[0047] The fifth sealing group 903 is located between the outer cylindrical surface of the main valve sleeve 9 and the inner wall of the main valve cavity 804 of the main valve body 806. It can be an O-ring seal to prevent oil from leaking to the outside or entering unrelated oil passages from the assembly gap between the main valve sleeve 9 and the main valve body 806.

[0048] In addition, an end face seal can be provided at the mating surface between the main valve end cover 805 and the main valve body 806 to prevent pressure oil from leaking out of the mating surface.

[0049] The aforementioned fourth sealing group 902, fifth sealing group 903, and end face seal work together with the first sealing group 302, second sealing group 702, and third sealing group 703 inside the integrated main valve core 1 to construct a fully sealed, highly reliable pressure control unit, ensuring the long-term stable operation of the unloading valve under high pressure.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A type of internally mounted pilot-operated main valve core, characterized in that, include: The main valve core (1) has a pilot cavity (101) inside, and a first through hole (102) and a second through hole (103) connecting the pilot cavity (101); The control valve core (2) is installed in the pilot cavity (101), and a third through hole (201) is opened in the center to connect with the first through hole (102). The control valve core (2) moves toward or away from the first through hole (102). A pilot valve sleeve (3) is installed in the pilot cavity (101), with one end abutting against the control valve core (2), and a pilot port (301) is opened on the side close to the control valve core (2); The pilot valve core (4) is installed inside the pilot valve sleeve (3), abuts against the pilot port (301), and moves toward or away from the first through hole (102). The outer wall of the pilot valve core (4) has a flow groove (401) along the length direction. A plug (5) is installed on the side of the main valve core (1) away from the control valve core (2), and a fourth through hole (501) is opened in the center to connect to the flow groove (401); A pilot spring (6) is installed in the pilot cavity (101), with one end abutting against the pilot valve core (4) and the other end abutting against the plug (5).

2. The internally mounted pilot-operated main valve core according to claim 1, characterized in that, A control valve sleeve (7) is also provided in the pilot cavity (101), which is sleeved on the control valve core (2), with one end abutting the pilot valve sleeve (3) and the other end abutting the main valve core (1).

3. The internally mounted pilot-operated main valve core according to claim 2, characterized in that, A fifth through hole (701) is provided on the control valve sleeve (7) to connect the second through hole (103) and the internal space of the control valve sleeve (7).

4. The internally mounted pilot-operated main valve core according to claim 1, characterized in that, The pilot valve core (4) is configured with a variable diameter at one end facing the pilot port (301).

5. The internally mounted pilot-operated main valve core according to claim 1, characterized in that, A first sealing assembly (302) is provided between the pilot valve sleeve (3) and the main valve core (1).

6. The internally mounted pilot-operated main valve core according to claim 2, characterized in that, A second sealing group (702) is provided between the control valve core (2) and the control valve sleeve (7), and a third sealing group (703) is provided between the control valve sleeve (7) and the main valve core (1).

7. A relief valve, employing the internally mounted pilot-operated main valve core as described in any one of claims 1 to 6, characterized in that, include: The main valve assembly (8) has a preload pressure oil inlet (801), a return oil inlet (802) and a high pressure oil inlet (803), and has a main valve chamber (804) inside, which is connected to the preload pressure oil inlet (801), the return oil inlet (802) and the high pressure oil inlet (803); The main valve sleeve (9) is disposed in the main valve chamber (804) and extends along the preload pressure oil inlet (801) to the return oil port (802). A sixth through hole (901) is provided on the main valve sleeve (9). The main valve core (1) is disposed inside the main valve sleeve (9) and moves toward or away from the return oil port (802). The first through hole (102) is connected to the return oil port (802), the second through hole (103) is connected to the high pressure oil inlet (803), and the fourth through hole (501) is connected to the preload pressure oil inlet (801). The main valve spring (10) is installed inside the main valve sleeve (9), with one end abutting against the main valve core (1) and the other end abutting against the main valve assembly (8).

8. The unloading valve according to claim 7, characterized in that, The main valve assembly (8) includes a main valve end cap (805) and a main valve body (806). The main valve body (806) has a main valve chamber (804) inside. The main valve end cap (805) has a preload pressure oil inlet (801). The main valve body (806) has a return oil port (802) and a high-pressure oil inlet (803).

9. The unloading valve according to claim 8, characterized in that, A one-way valve (8051) is provided on the main valve end cover (805) and connected to the preload pressure oil inlet (801).

10. The unloading valve according to claim 8, characterized in that, A fourth sealing group (902) is provided between the main valve core (1) and the main valve sleeve (9), and a fifth sealing group (903) is provided between the main valve sleeve (9) and the main valve body (806).

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