Three-stage pilot inversely-proportional pressure-reducing solenoid valve

Abstract

Disclosed is a three-stage pilot inversely-proportional pressure-reducing solenoid valve, which uses a sliding valve-type pilot valve structure. A second radially outward-projecting ring (332) and a spool (331) are integrated into a single part, namely a three-stage valve core (33). When the three-stage valve core (33) moves, two ends thereof are supported by a bearing (37) inside a stopper (31) and by an inner hole of a guide sleeve (321) to form a stable dual-support structure, thereby reducing contact friction problems caused by eccentricity between the three-stage valve core (33) and a valve body (21).

Description

A three-stage pilot-operated inverse proportional pressure reducing solenoid valve Technical Field

[0001] This invention relates to solenoid valves, and more specifically to a three-stage pilot-operated inverse proportional pressure-reducing solenoid valve. Background Technology

[0002] Three-stage pilot-operated inverse-proportional pressure-reducing solenoid valves (VFS) are commonly used in high-pressure, high-flow-rate precision fluid pressure control systems. They consist of an electromagnetic control unit that adjusts its internal mechanical structure based on changes in electrical signals to achieve precise pressure control. The first stage is typically a small pilot valve that controls the second stage, which in turn controls the third stage, ultimately reaching the main valve for precise pressure regulation. This multi-stage pilot design improves the valve's response speed and accuracy, making it particularly suitable for systems requiring very fine pressure adjustment, such as automated control systems or precision hydraulic systems.

[0003] In Oslin-type three-stage pilot-operated inverse proportional pressure-reducing solenoid valves, due to the high operating pressure and large pressure application area of ​​the main valve, a single electromagnetic force is often insufficient to directly control the main valve. Therefore, this design employs a three-stage pilot-operated amplification structure to enhance control strength and accuracy.

[0004] The first-stage pilot valve uses a spool valve structure, while the second-stage and third-stage pilot valves both use a plate-type relief valve structure. These valves are used to control or limit fluid pressure so that the internal pressure reaches the set value, making them suitable for applications requiring precise control.

[0005] In a plate-type relief valve, the plate or valve core moves under fluid pressure to control the flow rate or pressure of the fluid. This movement can cause vibrations in the valve structure, and dynamic changes in the fluid (such as flow velocity and pressure fluctuations) further affect these vibrations, forming a complex coupled vibration system. This leads to the inherent coupled vibration problem of the plate-type relief valve structure. Once coupled vibration occurs, the regulating effect of the solenoid valve will be significantly reduced. Suspension systems typically require valves to respond quickly to dynamic load changes, which means that the valve needs to operate stably at high frequencies. However, the mechanical structure (such as a plate-type relief valve) itself cannot effectively suppress or isolate high-frequency vibrations caused by dynamic fluid changes. Furthermore, in plate-type relief valves, the space and design options available for increasing damping or isolating vibrations may be very limited, which restricts the possibility of achieving effective vibration control in high-frequency applications.

[0006] In the Oslin three-stage pilot-operated proportional pressure reducing solenoid valve, the electromagnetic drive part adopts a structure with a welded magnetic ring, which can be used for suspension system pressures of 30MPa and above. However, welding and airtightness testing increase product costs, and there is a possibility of internal leakage due to welding defects. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing high-pressure, high-flow proportional solenoid valves used in suspension systems, such as the plate-type relief valve structure which suffers from vibration instability, and the complex structure of the electromagnetic drive part which has the risk of product failure due to internal leakage. In response, this invention provides a three-stage pilot-operated inverse proportional pressure reducing solenoid valve.

[0008] To address the shortcomings of the existing technology, the present invention provides the following technical solution: A three-stage pilot-operated inverse proportional pressure-reducing solenoid valve, comprising a yoke and a stop assembly; characterized in that: the yoke is annular, with a valve body assembly and a coil assembly respectively disposed at both ends of the yoke, the valve body assembly, the yoke, and the coil assembly forming a first cavity; the valve body assembly comprises an annular valve body, a first-stage valve core assembly, and a main spring, the valve body having a plurality of circumferentially distributed first radial through holes along the radial direction; the stop assembly comprises a stop and a small spring; the stop is located within the first cavity, a flow channel gap is provided between the outer wall of the stop near the valve body and the inner wall of the first cavity, the stop having a first axial blind hole opening towards the valve body along the axial direction, and a second-stage valve core, a third-stage valve core, and an armature sequentially disposed along the axial direction from the outside to the inside within the first axial blind hole; The secondary valve core includes an annular guide cylinder, a first radially outwardly protruding ring disposed on the outer wall of the guide cylinder, and a radially inwardly protruding ring disposed on the inner wall of the guide cylinder near the valve body assembly. The inner hole of the radially inwardly protruding ring forms a first damping hole. The tertiary valve core includes an annular push rod, a second radially outwardly protruding ring disposed on the outer wall of the push rod, and multiple second radially through holes disposed on the inner wall of the push rod near the secondary valve core. One end of the push rod extends into the guide cylinder and is limited by the radially inwardly protruding ring of the guide cylinder. The outer diameter of the limiting push rod is related to the guide cylinder. The inner diameter of the cylinder is adapted to the cylinder and can slide relative to each other to seal multiple second radial through holes. The other end of the push rod is fitted with a bearing and a pole shoe in sequence from the inside to the outside along the radial direction, and the end is used to abut against the armature. Multiple first axial through holes are evenly distributed around the circumference on the second radially convex ring. The inner wall of the first axial blind hole is provided with a first annular groove and a second annular groove that are adapted to the outer circumference of the first radially convex ring and the second radially convex ring, respectively. Multiple third radial through holes are evenly distributed around the circumference on the side wall of the second annular groove. The inner wall of the valve body, the first-stage valve core assembly, and the second-stage valve core form a first pilot cavity, and the main spring is located in the first pilot cavity. The cavity between the inner wall of the guide cylinder, the inner wall of the push rod, and the cavity between the outer wall of the armature, the limit push rod, the pole shoe, the bearing, and the inner wall of the first axial blind hole forms a second pilot cavity. The second-stage valve core, the third-stage valve core, and the inner wall of the first axial blind hole form an annular third pilot cavity, and the small spring is located in the third pilot cavity. The first pilot cavity is connected to the outside through a flow channel on the first-stage valve core assembly. The first pilot cavity is connected to the second pilot cavity through a first damping hole. The second pilot cavity is connected to the third pilot cavity through a second radial through hole. The third pilot cavity is connected to the outside in sequence through multiple first axial through holes, a second annular groove, multiple third radial through holes, and a flow channel gap, or in sequence through the gap between the second radial outward protrusion ring and the inner wall of the first axial blind hole, a second annular groove, multiple third radial through holes, and a flow channel gap.The minimum radial cross-sectional area of ​​the flow channel in the primary valve core assembly is less than the radial cross-sectional area of ​​the first damping orifice, and the radial cross-sectional area of ​​the first damping orifice is less than the sum of the radial cross-sectional areas of the plurality of third radial through holes.

[0009] Furthermore, the primary valve core assembly includes a valve seat, a primary valve core, and a leaf spring arranged sequentially from the outside to the inside of the valve body along the axial direction; the main spring is disposed between the leaf spring and the primary valve core; the valve seat and the primary valve core are respectively provided with a valve seat through hole and a second damping hole that are connected in sequence; the radial cross-sectional area of ​​the valve seat through hole is larger than the radial cross-sectional area of ​​the second damping hole, and the radial cross-sectional area of ​​the second damping hole is smaller than the radial cross-sectional area of ​​the first damping hole; the first pilot cavity is connected to the outside in sequence through the second damping hole and the valve seat through hole.

[0010] Furthermore, the leaf spring and the main spring are an integral structure.

[0011] Furthermore, an axial concave ring is provided at one end of the second radially convex ring near the secondary valve core, and the plurality of first axial through holes are provided on the bottom surface of the axial concave ring.

[0012] Furthermore, at least one annular groove and one annular boss are sequentially provided along the axial direction on the inner wall of the yoke near the end of the valve body assembly; the position of the annular groove corresponds to the position of the second annular groove, and at least one notch is provided on the inner circumference of the annular boss, and all the annular grooves and all the notches constitute the flow channel gap.

[0013] Furthermore, there are multiple annular grooves, and the diameter of the multiple annular grooves gradually increases along the axial direction and towards the valve body assembly.

[0014] Furthermore, it also includes a retaining ring, the coil assembly including a coil-encapsulated plug disposed at the other end of the yoke, and a coil body disposed between the inner wall of the yoke and the outer wall of the stop; the retaining ring is disposed between the coil body and the inner wall of the yoke.

[0015] Furthermore, a third annular groove is provided on the inner wall of the yoke, and an annular cavity is formed between the inner wall of the third annular groove and the outer wall of the stop; the coil body is disposed in the annular cavity, and the coil body includes a coil frame, enameled wire, coil plastic coating and magnetic circuit board; the retaining spring is disposed between the coil plastic coating and the inner wall of the third annular groove.

[0016] Furthermore, a composite coating is provided on the inner wall of the first axial blind hole at the position corresponding to the armature.

[0017] Furthermore, the armature is provided with at least one second axial through hole along the axial direction, or a gap is provided between the armature and the inner wall of the first axial blind hole.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention provides a three-stage pilot-operated inverse proportional pressure reducing solenoid valve, which adopts a spool valve type pilot valve structure, integrating the second radially outward convex ring and the push rod into a single part (three-stage valve core). When the three-stage valve core moves, both ends are supported by the bearings in the stop iron and the inner hole of the guide cylinder, forming a stable double support structure; while the plate type overflow valve structure used in the Oslin type three-stage pilot-operated inverse proportional pressure reducing solenoid valve lacks an axial guide limiting structure for the three-stage valve core. During the movement, under the impact of liquid flow, the three-stage valve core will rub against the valve body due to eccentricity, resulting in product stability problems; the present invention eliminates the contact friction problem caused by eccentricity between the three-stage valve core and the valve body.

[0019] (2) The present invention provides a three-stage pilot-operated inverse proportional pressure reducing solenoid valve, which adopts a symmetrical main valve flow channel design and a double-supported two-stage pilot valve structure, and has good pressure stability.

[0020] (3) The present invention provides a three-stage pilot-operated inverse proportional pressure reducing solenoid valve, which reduces the number of parts by 4 compared to the Oslin type three-stage pilot-operated inverse proportional pressure reducing solenoid valve (reducing 1 bearing, 1 magnetic isolation ring, 1 push rod, and 1 leaf spring); due to the adoption of an integrated stop proportional electromagnet structure based on particle flow, the parts are formed in one process and do not need to be processed in the second process. The production process of the present invention reduces 2 laser welding processes and 1 post-weld processing process, so the production efficiency is higher, the cost is lower, and the quality is more stable. Attached Figure Description

[0021] Figure 1 is a front view of an embodiment of the present invention; Figure 2 is a bottom view of an embodiment of the present invention; Figure 3 is a sectional view along line AA of Figure 1; Figure 4 is a sectional view of the valve body assembly in an embodiment of the present invention; Figure 5 is a structural schematic diagram of the stop assembly in an embodiment of the present invention; Figure 6 is a structural schematic diagram of the three-stage valve core in an embodiment of the present invention; Figure 7 is a sectional view of the armature in an embodiment of the present invention; Figure 8 is a sectional view of the stop in an embodiment of the present invention; Figure 9 is a sectional view of the yoke in an embodiment of the present invention; Figure 10 is a sectional view of the coil body in an embodiment of the present invention; Figure 11 is a structural schematic diagram of the coil skeleton in an embodiment of the present invention; Figure 12 is a structural schematic diagram of the enameled wire in an embodiment of the present invention; Figure 13 is a structural schematic diagram of the magnetic circuit board in an embodiment of the present invention; Figure 14 is a structural schematic diagram of the coil plastic coating in an embodiment of the present invention; Figure 15 is a schematic diagram of the working principle of the first pilot cavity, the second pilot cavity, and the third pilot cavity in an embodiment of the present invention (I); Figure 16 is a schematic diagram of the working principle of the first pilot cavity, the second pilot cavity, and the third pilot cavity in an embodiment of the present invention (II).

[0022] The reference numerals in the attached drawings are explained as follows: 1-Yoke, 11-Third annular groove, 12-Annular groove, 13-Annular boss, 14-Notch; 2-Valve body assembly, 21-Valve body, 211-First radial through hole, 22-Main spring, 23-Valve seat, 231-Valve seat through hole, 24-First stage valve core, 241-Second damping hole, 25-Leaf spring; 3-Stop assembly, 31-Stop, 311-First annular groove, 312-Second annular groove, 3121-Third radial through hole, 32-Secondary valve core, 321-Guide cylinder, 322-First radial outward convex ring, 323-Radial inward convex ring, 324-First damping hole, 33-Third-stage valve core, 331-Push rod, 332-Second radial outward convex ring, 333-Second radial through hole, 334-Axial concave ring, 335-First axial through hole, 34-Armature, 341-Second axial through hole, 35-Small spring, 36-Pole shoe, 37-Bearing, 38-Composite coating; 4-Coil assembly, 41-Coil plastic-encapsulated plug, 42-Coil body, 421-Coil frame, 422-Enameled wire, 423-Coil plastic coating, 424-Magnetic circuit board; 5-Snap ring; 10 - First pilot cavity, 20 - Second pilot cavity, 30 - Third pilot cavity. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0024] Referring to Figures 1 to 14, a three-stage pilot-operated inverse proportional pressure reducing solenoid valve includes a yoke 1, a valve body assembly 2, a stop assembly 3, a coil assembly 4, and a snap ring 5.

[0025] Referring to Figures 1 to 3, the yoke 1 is annular, with the valve body assembly 2 disposed at one end and the coil assembly 4 disposed at the other end. The valve body assembly 2, the yoke 1, and the coil assembly 4 form a first cavity, and the stop assembly 3 is disposed in the first cavity.

[0026] Referring to Figure 4, the valve body assembly 2 includes an annular valve body 21, and a valve seat 23, a primary valve core 24, a main spring 22, and a leaf spring 25 arranged sequentially from the outside to the inside along the axial direction within the valve body 21; the valve seat 23, the primary valve core 24, and the leaf spring 25 constitute a primary valve core assembly. The valve body 21 is provided with a plurality of circumferentially distributed first radial through holes 211; the valve seat 23 and the primary valve core 24 are respectively provided with valve seat through holes 231 and second damping holes 241 that are connected sequentially.

[0027] As a preferred option, the leaf spring 25 and the main spring 22 can be integrated into one unit, using a variable stiffness spring to achieve the same function, thereby reducing the number of parts and reducing costs.

[0028] Referring to Figure 5, the stop assembly 3 includes a stop 31, a secondary valve core 32, a tertiary valve core 33, an armature 34, a small spring 35, a pole shoe 36, a bearing 37, and a composite coating 38.

[0029] The stop 31 is located in the first cavity. A flow channel gap is provided between the outer wall of the stop 31 near the valve body 21 and the inner wall of the first cavity. The stop 31 has a first axial blind hole with an opening facing the valve body 21. The secondary valve core 32, the tertiary valve core 33 and the armature 34 are arranged sequentially in the first axial blind hole along the axial direction.

[0030] Referring to Figure 5, the secondary valve core 32 includes an annular guide cylinder 321, a first radially outward protruding ring 322 disposed on the outer side wall of the guide cylinder 321, and a radially inward protruding ring 323 disposed on the inner side wall of the end of the guide cylinder 321 near the valve body assembly 2. The inner hole of the radially inward protruding ring 323 forms a first damping hole 324.

[0031] The radial cross-sectional area of ​​the first damping hole 324 is greater than that of the second damping hole 241.

[0032] Referring to Figures 5 and 6, the three-stage valve core 33 includes an annular push rod 331, a second radially outward protruding ring 332 disposed on the side wall of the push rod 331 near the secondary valve core 32, and a plurality of second radially through holes 333 disposed on the side wall of the push rod 331. One end of the push rod 331 extends into the opening at one end of the guide cylinder 321 and is limited by the radially inward protruding ring 323 of the guide cylinder 321. The outer diameter of the limiting push rod 331 is adapted to the inner diameter of the guide cylinder 321 and can be relatively... The sliding mechanism blocks multiple second radial through holes 333. The other end of the push rod 331 is provided with a bearing 37 and a pole shoe 36 radially from the inside to the outside, and the end is used to abut against the armature 34. The second radially convex ring 332 is provided on the outer wall of the push rod 331. The end of the second radially convex ring 332 near the secondary valve core 32 is provided with an axial concave ring 334. The bottom surface of the axial concave ring 334 is provided with multiple circumferentially distributed first axial through holes 335.

[0033] Referring to Figure 5, a composite coating 38 is provided on the inner wall of the first axial blind hole at the position corresponding to the armature 34. Referring to Figure 7, the armature 34 is provided with two second axial through holes 341 symmetrically arranged along the axial direction.

[0034] Referring to Figure 8, the inner wall of the first axial blind hole is provided with a first annular groove 311 and a second annular groove 312 that are adapted to the outer periphery of the first radially convex ring 322 and the second radially convex ring 332, respectively; the first annular groove 311 is used to axially limit the first radially convex ring 322, and the side wall of the second annular groove 312 is provided with a plurality of circumferentially distributed third radial through holes 3121, and the radial cross-sectional area of ​​the first damping hole 324 is less than the sum of the radial cross-sectional areas of the plurality of third radial through holes 3121.

[0035] Referring to Figure 9, the inner wall of the yoke 1 is provided with a third annular groove 11, and three annular grooves 12 and an annular boss 13 are arranged sequentially along the axial direction and close to the valve body assembly 2; the inner side wall of the third annular groove 11 and the outer side wall of the stop 31 form an annular cavity; the diameter of the three annular grooves 12 gradually increases along the axial direction and close to the valve body assembly 2, and corresponds to the position of the second annular groove 312; the inner circumference of the annular boss 13 is provided with two circumferentially distributed notches 14.

[0036] Referring to Figures 3, 10 to 14, the coil assembly 4 includes a coil plastic-encapsulated plug 41 disposed at the other end of the yoke 1, and a coil body 42 disposed in the annular cavity; the coil body 42 includes a coil frame 421, enameled wire 422, coil plastic coating 423, and magnetic circuit board 424.

[0037] Referring to Figures 3, 5, 8, 15, and 16, the inner wall of the valve body 21, the first-stage valve core 24, and the second-stage valve core 32 form a first pilot cavity 10, and the main spring 22 is located within the first pilot cavity 10; the cavity between the inner wall of the guide cylinder 321, the inner wall of the push rod 331, the outer wall of the armature 34, the limit push rod 331, the pole shoe 36, the bearing 37, and the inner wall of the first axial blind hole forms a second pilot cavity 20; the second-stage valve core 32, the third-stage valve core 33, and the inner wall of the first axial blind hole form an annular third pilot cavity 30, and the small spring 35 is located within the third pilot cavity 30. The first pilot cavity 10 is connected to the outside via the second damping hole 241 and the valve seat through hole 231 in sequence. The first pilot cavity 10 is connected to the second pilot cavity 20 via the first damping hole 324. The second pilot cavity 20 is connected to the third pilot cavity 30 via the second radial through hole 333. The third pilot cavity 30 is connected to the outside via multiple first axial through holes 335, a second annular groove 312, multiple third radial through holes 3121, and a flow channel gap in sequence. Alternatively, it is connected via the gap between the second radial outward protruding ring 332 and the inner wall of the first axial blind hole, the second annular groove 312, multiple third radial through holes 3121, and a flow channel gap in sequence.

[0038] Referring to Figures 3 and 9, the retaining ring 5 is disposed between the coil coating 423 and the inner wall of the third annular groove 11.

[0039] The working principle of this invention is as follows: 1. When this invention is not powered: The first-stage valve core 24 is subjected to the oil pressure force at port P, the elastic force of the main spring 22, and the elastic force of the leaf spring 25; when the pressure at port P is small, the main spring 22 is slightly compressed, and the elastic force of the leaf spring 25 plays a major role, pressing the end face of the first-stage valve core 24 onto the valve seat 23. There is no gap between the first-stage valve core 24 and the valve seat 23, and the liquid cannot flow directly from port P to port A; because the radial cross-sectional area of ​​the first damping orifice 324 is larger than the radial cross-sectional area of ​​the second damping orifice 241, the pressure in the second pilot chamber 20 is less than the pressure in the first pilot chamber 10; because the radial cross-sectional area of ​​the first damping orifice 324 is smaller than the radial cross-sectional area of ​​the multiple third radial through holes 3121 The sum of the radial cross-sectional areas of the two pilot chambers causes the pressure in the third pilot chamber 30 to be less than that in the second pilot chamber 20. At this time, the liquid flows from the outside into the first pilot chamber 10 through the valve seat through hole 231 (P port) and the second damping hole 241, then into the second pilot chamber 20 through the first damping hole 324, and then into the third pilot chamber 30 through multiple second radial through holes 333. Finally, it flows out through the gap between the second radial outward protruding ring 332 and the inner wall of the first axial blind hole, the second annular groove 312, multiple third radial through holes 3121, three annular grooves 12, and two notches 14 (T port) (arrows in Figure 15). When the pressure at port P continues to increase, the pressure at port P is greater than the resultant force of the elastic force of the leaf spring 25 and the main spring 22. The first-stage valve core 24 is lifted away from the valve seat 23 by the hydraulic pressure. The first-stage valve core 24 and the valve seat 23 form a flow channel, and the liquid flows directly from port P to port A.

[0040] 2. When the present invention is energized: The armature 34 is subjected to electromagnetic force on the three-stage valve core 33, and the three-stage valve core 33 is subjected to the pressure of the third pilot chamber 30 and the pressure of the second pilot chamber 20; when the electromagnetic force is greater than the resultant force of the pressure of the third pilot chamber 30 and the pressure of the second pilot chamber 20, the three-stage valve core 33 moves towards the first-stage valve core 24, and the liquid flows through the inner hole of the push rod 331 and the second radial through hole 333 to the second annular groove 312 on the stop 31, the flow channel area increases rapidly, the pressure of the third pilot chamber 30 decreases rapidly, and then the pressure of the second pilot chamber 20 and the pressure of the first pilot chamber 10 decrease rapidly. The first-stage valve core 24 is quickly opened to a large degree by the pressure of port P, and the pressure of port A increases rapidly. As the current through the present invention continues to increase, the electromagnetic force continues to increase, the third-stage valve core 33 moves toward the second-stage valve core 32, and the flow channel formed by the second radial through hole 333 of the third-stage valve core 33 and the inner hole of the guide cylinder 321 continues to shrink, resulting in an increase in the pressure in the second pilot chamber 20, and then an increase in the pressure in the first pilot chamber 10. Under the action of the pressure in the first pilot chamber 10, the spring force of the main spring 22 and the leaf spring 25, and the pressure at port P, the third-stage valve core 33 moves toward the valve seat 23, and the opening between the first-stage valve core 24 and the valve seat 23 decreases, and the pressure at port A continues to decrease. As the electromagnetic force continues to increase, the third-stage valve core 33 moves towards the first-stage valve core 24 until the guide cylinder 321 blocks the multiple second radial through holes 333. The flow channel formed by the multiple second radial through holes 333 of the third-stage valve core 33 and the inner hole of the guide cylinder 321 is closed, the pressure in the second pilot chamber 20 reaches its maximum, and then the pressure in the first pilot chamber 10 reaches its maximum. Under the action of the pressure in the first pilot chamber 10, the spring force, and the pressure at port P, the first-stage valve core 24 is pressed against the valve seat 23, and the pressure at port A reaches its minimum. At this time, referring to the arrow in Figure 16, the first axial through hole 335, the second annular groove 312, the multiple third radial through holes 3121, the three annular grooves 12, and the two notches 14 (T ports) are connected in sequence, and the liquid flows out from the third pilot chamber 30 to the outside.

Claims

1. A three-stage pilot counter proportional pressure reducing solenoid valve, comprising a yoke (1) and a stopper assembly (3); characterized in that: the yoke (1) is annular, and a valve body assembly (2) and a coil assembly (4) are arranged at two ends of the yoke (1) respectively, and a first cavity is formed among the valve body assembly (2), the yoke (1) and the coil assembly (4); the valve body assembly (2) comprises an annular valve body (21), a primary spool assembly and a main spring (22), and a plurality of first radial through holes (211) are arranged on the valve body (21) in a circumferential direction; the stopper assembly (3) comprises a stopper (31) and a small spring (35); the stopper (31) is located in the first cavity, and a flow passage gap is arranged between an outer side wall of one end of the stopper (31) close to the valve body (21) and an inner wall of the first cavity, and a first axial blind hole with an opening facing the valve body (21) is arranged on the stopper (31) in an axial direction, and a secondary spool (32), a tertiary spool (33) and an armature (34) are sequentially arranged in the first axial blind hole from outside to inside in the axial direction; the secondary spool (32) comprises an annular guide cylinder (321), a first radial outer convex ring (322) arranged on an outer side wall of the guide cylinder (321), and a radial inner convex ring (323) arranged on an inner side wall of one end of the guide cylinder (321) close to the valve body assembly (2), and an inner hole of the radial inner convex ring (323) constitutes a first damping hole (324); the tertiary spool (33) comprises an annular top rod (331), a second radial outer convex ring (332) arranged on an outer side wall of the top rod (331), and a plurality of second radial through holes (333) arranged on a side wall of one end of the top rod (331) close to the secondary spool (32), one end of the top rod (331) extends into the guide cylinder (321), and is limited by the radial inner convex ring (323) of the guide cylinder (321), an outer diameter of the limited top rod (331) is matched with an inner diameter of the guide cylinder (321), and the plurality of second radial through holes (333) can be blocked relatively, the other end of the top rod (331) is sequentially sleeved with a bearing (37) and a pole shoe (36) from inside to outside in a radial direction, and an end portion is used for abutting against the armature (34); a plurality of first axial through holes (335) are arranged on the second radial outer convex ring (332) in a circumferential direction; and a first annular groove (311) and a second annular groove (312) matched with outer circumferences of the first radial outer convex ring (322) and the second radial outer convex ring (332) are arranged on an inner wall of the first axial blind hole respectively; and a plurality of third radial through holes (3121) are arranged on a side wall of the second annular groove (312) in a radial direction. The first pilot chamber (10) is formed between the inner wall of the valve body (21), the primary valve core assembly and the secondary valve core (32), and the main spring (22) is located in the first pilot chamber (10); the second pilot chamber (20) is formed between the inner wall of the guide cylinder (321), the inner wall of the top rod (331), the outer wall of the armature (34) limiting the top rod (331), the pole shoe (36), the bearing (37) and the inner wall of the first axial blind hole; the third pilot chamber (30) is annularly formed between the secondary valve core (32), the tertiary valve core (33) and the inner wall of the first axial blind hole, and the small spring (35) is located in the third pilot chamber (30); the first pilot chamber (10) is in communication with the outside through the flow channel on the primary valve core assembly, the first pilot chamber (10) is in communication with the second pilot chamber (20) through the first damping hole (324), the second pilot chamber (20) is in communication with the third pilot chamber (30) through the second radial through hole (333), and the third pilot chamber (30) is in communication with the outside through the plurality of first axial through holes (335), the second annular groove (312), the plurality of third radial through holes (3121) and the flow channel gap in sequence, or through the gap between the second radial outer convex ring (332) and the inner wall of the first axial blind hole, the second annular groove (312), the plurality of third radial through holes (3121) and the flow channel gap in sequence; the minimum value of the radial cross-sectional area of the flow channel of the primary valve core assembly is smaller than the radial cross-sectional area of the first damping hole (324), and the radial cross-sectional area of the first damping hole (324) is smaller than the sum of the radial cross-sectional areas of the plurality of third radial through holes (3121).

2. The three-stage pilot inverse proportional pressure reducing electromagnetic valve according to claim 1, characterized in that: the primary valve core assembly comprises, in sequence from the outside to the inside along the axial direction, a valve seat (23), a primary valve core (24) and a leaf spring (25) arranged in the valve body (21); the main spring (22) is arranged between the leaf spring (25) and the primary valve core (24); the valve seat (23) and the primary valve core (24) are respectively provided with a valve seat through hole (231) and a second damping hole (241) in sequence; the radial cross-sectional area of the valve seat through hole (231) is greater than the radial cross-sectional area of the second damping hole (241), and the radial cross-sectional area of the second damping hole (241) is smaller than the radial cross-sectional area of the first damping hole (324); the first pilot chamber (10) is in communication with the outside through the second damping hole (241) and the valve seat through hole (231) in sequence.

3. The three-stage pilot inverse proportional pressure reducing electromagnetic valve according to claim 2, characterized in that: the leaf spring (25) and the main spring (22) are of an integrated structure.

4. The three-stage pilot inverse proportional pressure reducing electromagnetic valve according to claim 1, characterized in that: the second radial outer convex ring (332) is provided with an axial concave ring (334) at one end close to the secondary valve core (32), and the plurality of first axial through holes (335) are arranged on the bottom surface of the axial concave ring (334).

5. A three-stage pilot-operated inverse proportional pressure reducing solenoid valve according to claim 1, characterized in that: On the inner wall of the yoke (1), near the end of the valve body assembly (2), at least one annular groove (12) and an annular boss (13) are sequentially arranged along the axial direction; the position of the annular groove (12) corresponds to the position of the second annular groove (312), and at least one notch (14) is provided on the inner circumference of the annular boss (13). All the annular grooves (12) and all the notches (14) constitute the flow channel gap.

6. A three-stage pilot-operated inverse proportional pressure-reducing solenoid valve according to claim 5, characterized in that: There are multiple annular grooves (12), and the diameter of the multiple annular grooves (12) gradually increases along the axial direction and towards the valve body assembly (2).

7. A three-stage pilot-operated inverse proportional pressure reducing solenoid valve according to any one of claims 1 to 6, characterized in that: It also includes a retaining ring (5), and the coil assembly (4) includes a coil plastic-encapsulated plug (41) disposed at the other end of the yoke (1), and a coil body (42) disposed between the inner wall of the yoke (1) and the outer wall of the stop (31); the retaining ring (5) is disposed between the coil body (42) and the inner wall of the yoke (1).

8. A three-stage pilot-operated inverse proportional pressure reducing solenoid valve according to claim 7, characterized in that: The inner wall of the yoke (1) is provided with a third annular groove (11), and the inner side wall of the third annular groove (11) and the outer side wall of the stop (31) form an annular cavity; the coil body (42) is disposed in the annular cavity, and the coil body (42) includes a coil frame (421), enameled wire (422), coil plastic coating (423) and magnetic circuit board (424); the retaining ring (5) is disposed between the coil plastic coating (423) and the inner wall of the third annular groove (11).

9. The three-stage pilot operated antipropotional pressure reducing solenoid valve according to claim 8, characterized in that: A composite coating (38) is provided on the inner wall of the first axial blind hole at the position corresponding to the armature (34).

10. The three-stage pilot operated antipropotional pressure reducing solenoid valve according to claim 9, characterized in that: The armature (34) is provided with at least one second axial through hole (341) along the axial direction, or a gap is provided between the armature (34) and the inner wall of the first axial blind hole.

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