Damping-adjustable external electromagnetic valve for shock absorber

Abstract

The utility model discloses an adjustable damping type external solenoid valve for a shock absorber, which comprises an electromagnet assembly and a damping valve group, the damping valve group at least comprises a valve body and a valve seat, the valve body is provided with a pilot chamber, and the pilot chamber is provided with a pilot valve. The pilot chamber is communicated with a valve port formed in the valve seat and a valve hole formed in the outer circumferential surface of the valve body; a main valve element is arranged in the pilot chamber, and the inner side of the main valve element abuts against the end side of the valve body through a spiral spring. A liquid inlet hole is formed in the main valve element, a liquid outlet hole is formed in the end side of the valve body, and the liquid outlet hole is communicated with the outside through a flow channel between the electromagnet assembly and the damping valve set. The electromagnet assembly at least comprises a push rod arranged in a sliding mode, a gasket is arranged on the push rod, and the gasket can seal the liquid outlet hole. The electromagnetic valve is mainly embodied in that the design is exquisite, fluid pressure can be quickly relieved through the electromagnetic valve, instant sudden change is avoided, the fluid pressure control precision is greatly improved, and the electromagnetic valve has wide applicability.

Description

Adjustable damping external solenoid valve for shock absorbers Technical Field

[0001] This utility model relates to the field of electromagnetic technology, and more specifically, to an adjustable damping external solenoid valve for shock absorbers. Background Technology

[0002] The valve assembly in the vehicle absorbs some of the vibrations from the damper without transmitting them to the chassis, thus making the ride smoother.

[0003] As disclosed in CN 116917642 A, a valve assembly for a shock absorber is described. This valve assembly includes: a valve housing with a first port and a second port; a pilot chamber in fluid communication with the first port and / or the second port, the pilot pressure being determined by hydraulic pressure within the pilot chamber; and a main valve member axially movable within the valve housing along a longitudinal axis to restrict the main fluid flow between the first port and the second port in response to the pilot pressure acting on the main valve member. Furthermore, the main valve member is elastically loaded in a steady-state position, from which it is movable in two directions along the longitudinal axis and configured to move away from the pilot chamber during an initial pressure increase in the main fluid. However, when the pilot chamber of this valve assembly is subjected to a sudden high-pressure impact, the pressure relief structure cannot quickly release the generated pressure to establish a new equilibrium. Under the influence of the pressure impact, the main valve core overshoots, causing excessive pressure relief in the pilot chamber, resulting in unstable pressure control at the main valve core and sudden changes in pressure curve, leading to abrupt changes in the solenoid valve pressure curve. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an adjustable damping external solenoid valve for shock absorbers.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] An adjustable damping external solenoid valve for a shock absorber includes an electromagnet assembly and a damping valve group disposed at one end thereon.

[0007] The damping valve assembly includes at least a valve body and a valve seat disposed at one end of the valve body. The valve body has a pilot chamber that communicates with a valve port opened on the valve seat and a valve hole opened on the outer circumferential surface of the valve body.

[0008] The pilot chamber contains a main valve core that can seal the valve body. The outer side of the main valve core can abut against the valve seat, separating the connection channel between the valve port and the valve hole. The inner side of the main valve core abuts against the end side of the valve body through a helical spring. The main valve core can slide along the central axis of the valve body under the force applied by the fluid, and the outer circumferential surface of the main valve core is always in close contact with the inner wall of the valve body.

[0009] The main valve core is provided with an inlet hole, and the valve body is provided with an outlet hole at one end. The outlet hole is connected to the outside through the flow channel between the electromagnet assembly and the damping valve group.

[0010] The electromagnet assembly includes at least a slidably disposed push rod, and a washer is provided on the push rod, which can block the liquid outlet hole;

[0011] The electromagnet assembly also includes a housing with a receiving cavity. A valve plate is fixedly installed in the receiving cavity. A valve body is fixedly installed on one side of the valve plate and a valve disc is fixedly installed on the housing on the other side. There is a liquid outlet groove between the valve disc and the valve plate and the push rod. A drain hole communicating with the liquid outlet is opened on the valve plate. The floating end of the valve disc can block the drain hole.

[0012] Preferably, the valve body is integrally formed and includes an annular end and a sealing end disposed at one end thereon. The valve hole is opened on the outer circumferential surface of the annular end. The end face is provided with an inwardly recessed large-diameter end and a small-diameter end in sequence. The helical spring is sleeved on the small-diameter end and abuts against the large-diameter end. A groove is opened on the small-diameter end, and a pilot seat is fixed in the groove. The liquid outlet hole is opened on the pilot seat.

[0013] Preferably, the pilot seat has a receiving cavity, the push rod can extend at least partially into the receiving cavity, the gasket abuts against the pilot seat, and the diameter of the gasket is larger than the diameter of the receiving cavity.

[0014] Preferably, the push rod is integrally formed, including a cylindrical end and a frustum end disposed at one end of the cylindrical end, the washer is sleeved on the frustum end and abuts against the cylindrical end; a push rod retaining spring groove is formed on the outer circumferential surface of the frustum end, the push rod retaining spring groove is internally fitted with a push rod retaining spring adapted thereto, and the outer circumferential surface of the push rod retaining spring abuts against the washer.

[0015] Preferably, the valve body, valve plate, and valve disc all have openings on their outer circumferential surfaces, and the gap between the openings and the housing constitutes the flow channel.

[0016] Preferably, the valve plate is integrally formed and includes a fixed end fixed to the housing, the fixed end being sleeved on the floating end, both the fixed end and the floating end being annular, a protrusion I being fixed on the inner wall of the fixed end, a protrusion II being fixed on the outer wall of the floating end, and an arc-shaped connecting piece being provided between the protrusion I and the protrusion II.

[0017] Preferably, a leaf spring and a stop plug are sleeved on the push rod. The stop plug is fixed on the housing. One end of the leaf spring abuts against the stop plug, and the other end abuts against the floating end.

[0018] Preferably, a sliding cavity is provided inside the housing, an armature is provided inside the sliding cavity, a push rod is fixed on the armature, an armature spring is sleeved on the push rod, one end of the armature spring abuts against the armature, and the other end abuts against the stop plug; one end of the armature is provided with a fixed iron core fixed on the housing, a coil frame is sleeved on the outside of the armature, and a coil is wound on the coil frame.

[0019] Preferably, bearing sleeves are fitted on both sides of the push rod, and the bearing sleeves are respectively fixed on the stop plug and the housing.

[0020] Preferably, the housing is assembled from an outer shell and an inner shell, which cooperate to clamp the coil frame; the outer shell and the inner shell are provided with positioning spring grooves, and positioning springs adapted to them are provided in the positioning spring grooves.

[0021] The beneficial effects of this utility model are mainly reflected in:

[0022] 1. The design is ingenious. When the main valve core is subjected to high-pressure fluid impact, the helical spring can provide initial buffering and pressure relief. If the initial buffering and pressure relief cannot relieve the fluid pressure, the floating end is pushed to move backward against the spring force through the inlet, outlet and drain holes to achieve secondary pressure relief. If the fluid pressure still cannot be completely relieved, the gasket is separated from the valve plate by the solenoid valve to achieve tertiary pressure relief. This ensures that the fluid pressure is quickly relieved, avoiding sudden changes that could affect the pressure control of the main valve core and greatly improve the accuracy of fluid pressure control. It has a wide range of applicability.

[0023] 2. In this invention, the solenoid valve can still dampen the fluid even when the electromagnet assembly is not energized, greatly reducing energy consumption and benefiting environmental protection. Furthermore, its ingenious design eliminates the need for adjustments to the overall structure of the solenoid valve, significantly reducing costs. Additionally, the solenoid valve can adaptively dampen the fluid even when the electromagnet assembly is energized, making it widely applicable.

[0024] 3. The floating end can separate from the drain hole under the force of fluid pressure, realizing automatic damping adjustment. This operation is simple, stable, and reliable. In addition, the valve plate adopts an integrated structure, which facilitates assembly, reduces cost, and is beneficial for mass production.

[0025] 4. After the work is completed, the leaf spring can apply force to the floating end, so that the floating end always sticks tightly to the drain hole, blocking the drain hole and greatly improving work efficiency.

[0026] 5. The helical spring is designed to apply force to the main valve core after operation, causing it to reset and block the valve port on the valve seat. Furthermore, the smaller diameter end positions the helical spring, while the larger diameter end limits its movement, ensuring precise positioning and significantly improving assembly convenience.

[0027] 6. By using a push rod retainer to fix the shim, the axial displacement of the shim on the push rod can be precisely limited. This fixing method is simple, convenient, stable and reliable, and the installation and disassembly are quick, which greatly improves work efficiency.

[0028] 7. The bearing sleeve can reduce the vibration and offset of the push rod during operation, improve the accuracy of movement, and also reduce the friction coefficient between the push rod and the bearing sleeve, reduce the wear of the push rod, and extend its service life.

[0029] 8. The shell is made of an outer shell and an inner shell, which reduces the difficulty of operation, makes assembly more convenient, and ensures stable and reliable operation, greatly improving work efficiency. In addition, it also reduces processing costs and has a wide range of applicability. Attached Figure Description

[0030] The technical solution of this utility model will be further described below with reference to the accompanying drawings:

[0031] Figure 1: Cross-sectional view of a preferred embodiment of the present invention;

[0032] Figure 2: A perspective view of the valve plate in a preferred embodiment of this utility model. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments are not limited to the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present invention.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] As shown in Figures 1 and 2, this utility model discloses an adjustable damping external solenoid valve for a shock absorber, including an electromagnet assembly. Specifically, the electromagnet assembly includes at least a housing 5, with a sliding cavity 52 inside the housing 5. An armature 53 is disposed within the sliding cavity 52, and a coil frame 55 is sleeved on the outside of the armature 53. A coil 56 is wound on the coil frame 55. One end of the armature 53 is provided with a fixed iron core 54 fixed to the housing 5. A push rod 4 is fixed to the armature 53, and an armature spring 57 is sleeved on the push rod 4. One end of the armature spring 57 abuts against the armature 53, and the other end abuts against a stop plug 47 fixed to the housing 5. The armature spring 57 allows the armature 53 to be reset after the electromagnet assembly has finished working, ensuring accuracy for the next operation.

[0037] Furthermore, bearing sleeves 40 are fitted on both sides of the push rod 4. The bearing sleeves 40 are fixed on the stop plug 47 and the housing 5 respectively. The bearing sleeves 40 can reduce the vibration and offset of the push rod 4 during operation and improve the accuracy of movement. In addition, it can also reduce the friction coefficient between the push rod 4 and the bearing sleeves 40, reduce the wear of the push rod 4, and extend its service life.

[0038] In this invention, the housing 5 is composed of an outer shell 58 and an inner shell 59, which cooperate to clamp the coil frame 55. Positioning spring grooves 50 are provided on both the outer shell 58 and the inner shell 59, and positioning springs 501 are fitted into these grooves. The use of an outer shell and inner shell 59 to assemble the housing reduces operational difficulty, makes assembly more convenient, ensures stable and reliable operation, greatly improves work efficiency, and also reduces processing costs, thus having wide applicability.

[0039] Another key design feature of this utility model is that: a receiving cavity 51 is provided on the housing 5, and a damping valve assembly is provided in the receiving cavity 51. The damping valve assembly includes at least a valve body 1 and a valve seat 2 disposed at one end of the valve body 1. In this preferred embodiment, the valve seat 2 is fixedly disposed on the valve body 1 and can be fixedly connected by means of screwing, welding, etc., all of which fall within the protection scope of this utility model. The valve body 1 has a pilot chamber 11, which communicates with the valve port 21 opened on the valve seat 2 and the valve hole 12 opened on the outer circumferential surface of the valve body 1.

[0040] In this invention, the valve body 1 is integrally formed, including an annular end 15 and a sealing end 16 disposed at one end thereon. The valve hole 12 is formed on the outer circumferential surface of the annular end 15. The interior of the annular end 15 is a pilot chamber, and the pilot chamber 11 contains a main valve core 3 that can seal the valve body 1. The main valve core 3 can slide along the central axis of the valve body 1 under the force applied by the fluid, and the outer circumferential surface of the main valve core 3 is always in close contact with the inner wall of the valve body 1. The outer side of the main valve core 3 can abut against the valve seat 2, separating the connection channel between the valve port 21 and the valve hole 12. The inner side of the main valve core 3 can cooperate with the valve body 1 to form a sealing cavity. In a preferred embodiment, the main valve core 3 is provided with a liquid inlet hole 32.

[0041] Furthermore, the inner side of the main valve core 3 abuts against the end side of the valve body 1 via a helical spring 31. The helical spring 31, after operation, applies force to the main valve core 3, causing it to reset and block the valve port 21 on the valve seat 2. The end face 16 is sequentially provided with an inwardly recessed large-diameter end 17 and a small-diameter end 18. The helical spring 31 is sleeved on the small-diameter end 18 and abuts against the large-diameter end 17. This ingenious layout ensures the accuracy of the helical spring 31's position by positioning the small-diameter end and limiting its movement by the large-diameter end 17, while also significantly improving assembly convenience.

[0042] Additionally, a slot 19 is provided on the small-diameter end 18, and a pilot seat 10 is fixedly installed in the slot 19. The pilot seat 10 has the liquid outlet 13, which communicates with the outside through the flow channel 14 between the electromagnet assembly and the damping valve assembly. A gasket 41 is provided on the push rod 4, which can block the liquid outlet 13.

[0043] The pilot seat 10 has a receiving cavity 101, and the push rod 4 can extend at least partially into the receiving cavity 101. The gasket 41 abuts against the pilot seat 10, and the diameter of the gasket 41 is larger than the diameter of the receiving cavity 101. Specifically, the push rod 4 is integrally formed and includes a cylindrical end 42 and a frustum end 43 disposed at one end of the cylindrical end 42. The gasket 41 is sleeved on the frustum end 43 and abuts against the cylindrical end 42. A push rod retaining spring groove 44 is formed on the outer circumferential surface of the frustum end 43, and a push rod retaining spring 45 adapted to it is built into the push rod retaining spring groove 44. The outer circumferential surface of the push rod retaining spring 45 abuts against the gasket 41. The above-mentioned use of the push rod retaining spring 45 to fix the gasket 41 can accurately limit the axial displacement of the gasket 41 on the push rod 4. This fixing method is simple, convenient, stable and reliable, and the installation and disassembly are quick, which greatly improves work efficiency.

[0044] A valve plate 6 is fixedly installed inside the accommodating cavity 51. A valve body 1 is fixedly mounted on the housing 5 on one side of the valve plate 6, and a valve disc 7 is fixedly mounted on the housing 5 on the other side. Openings 9 are formed on the outer circumferential surfaces of the valve body 1, valve plate 6, and valve disc 7. The gap between the openings 9 and the housing 5 forms the flow channel 14. A liquid outlet groove 70 exists between the valve disc 7 and the valve plate 6 and the push rod 4. A drain hole 61 communicating with the liquid outlet 13 is formed on the valve plate 6. The floating end 71 of the valve disc 7 can block the drain hole 61.

[0045] In this invention, a leaf spring 46 and a stop plug 47 are sleeved on the push rod 4. The stop plug 47 is fixed to the housing 5. One end of the leaf spring 46 abuts against the stop plug 47, and the other end abuts against the floating end 71. After the work is completed, the leaf spring 46 can apply a force to the floating end 71, so that the floating end 71 is always in close contact with the drain hole, blocking the drain hole and greatly improving work efficiency.

[0046] Furthermore, the valve plate 7 is integrally formed and includes a fixed end 72 fixed to the housing 5. The fixed end 72 is sleeved on the floating end 71. Both the fixed end 72 and the floating end 71 are annular. A protrusion I 73 is fixed on the inner wall of the fixed end 72, and a protrusion II 74 is fixed on the outer wall of the floating end 71. An arc-shaped connecting piece 75 is provided between the protrusion I 73 and the protrusion II 74. The floating end 71 can separate from the drain hole under the force of the fluid to achieve damping adjustment. This operation is simple, stable, and reliable. In addition, the valve plate adopts an integral structure, which facilitates assembly and has low cost, making it beneficial for mass production.

[0047] The working process of this utility model is briefly described below:

[0048] When the electromagnet assembly is not energized, the armature spring 57 acts on the armature 53, the push rod 4 moves backward, and the gasket 41 abuts against the valve plate 6, blocking the outlet groove 70. When fluid flows in from the valve port 21, some fluid passes through the inlet hole 32, outlet hole 13, and drain hole 61, pushing the floating end 71 backward against the spring force of the leaf spring 46. The floating end 71 opens, quickly releasing the pressure in the main valve core from the flow channel 14. At this time, the fluid pressure in the valve port 21 is greater than the pressure in the main valve core, and the fluid exerts a force on the main valve core 3, overcoming the spring force of the helical spring 31, driving the main valve core 3 to move backward. At this time, most of the fluid flows out from the valve port 12. This design allows the solenoid valve to provide a certain damping effect on the fluid even when the electromagnet assembly is not energized, reducing energy consumption and benefiting environmental protection. In addition, this layout is ingenious and does not require any adjustment or change to the overall structure of the solenoid valve, greatly reducing costs.

[0049] When the electromagnet assembly is energized, if the current of the electromagnet assembly does not reach the predetermined value, the push rod 4 moves forward under the action of electromagnetic force, and the gasket 41 separates from the valve plate 6. When fluid flows in from the valve port 21, part of the fluid passes through the inlet hole 32, the outlet hole 13, and the drain hole 61, pushing the floating end 71 to move backward against the elastic force of the leaf spring 46. The floating end 71 opens, and the fluid flows into the flow channel 14. At the same time, fluid also flows into the flow channel 14 from the outlet groove 70, realizing the rapid release of pressure in the main valve core, which can realize the adjustment of damping and greatly improve working efficiency.

[0050] When the electromagnet assembly is energized and the current exceeds a predetermined value, the push rod 4 moves forward under the action of electromagnetic force, and the gasket 41 abuts against the pilot seat 10, thereby blocking the liquid outlet 13 and significantly increasing the damping force. The greater the current of the electromagnet assembly, the greater the force exerted by the gasket 41 on the pilot seat 10, and the greater the damping force on the fluid, achieving a highly efficient seal.

[0051] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0052] The detailed descriptions listed above are merely specific descriptions of feasible implementations of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementations or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. An adjustable damping external solenoid valve for a shock absorber, comprising an electromagnet assembly and a damping valve group disposed at one end thereof, characterized in that: The damping valve assembly includes at least a valve body (1) and a valve seat (2) disposed at one end of the valve body (1). The valve body (1) has a pilot chamber (11), which communicates with a valve port (21) opened on the valve seat (2) and a valve hole (12) opened on the outer circumferential surface of the valve body (1). The pilot chamber (11) contains a main valve core (3) that can seal the valve body (1). The outer side of the main valve core (3) can be connected to the valve seat (2). The valve seat (2) abuts against the valve, separating the connection channel between the valve port (21) and the valve hole (12). The inner side of the main valve core (3) abuts against the end side of the valve body (1) through a helical spring (31). The main valve core (3) can slide along the central axis of the valve body (1) under the force applied by the fluid, and the outer circumferential surface of the main valve core (3) is always in close contact with the inner wall of the valve body (1). The main valve core (3) is provided with an inlet hole (32). The valve body (1) The end side of the electromagnet is provided with a liquid outlet hole (13), which is connected to the outside through the flow channel (14) between the electromagnet assembly and the damping valve assembly; the electromagnet assembly includes at least a sliding push rod (4), and a gasket (41) is provided on the push rod (4), which can block the liquid outlet hole (13); the electromagnet assembly also includes a housing (5), which is provided with a receiving cavity (51), and a valve plate (6) is fixed in the receiving cavity (51). One side of the valve plate (6) is provided with a valve body (1) fixed on the housing (5), and the other side is provided with a valve plate (7) fixed on the housing (5). There is a liquid outlet groove (70) between the valve plate (7) and the valve plate (6) and the push rod (4). The valve plate (6) is provided with a drain hole (61) that communicates with the liquid outlet hole (13), and the floating end (71) of the valve plate (7) can block the drain hole (61).

2. The adjustable damping external solenoid valve for a shock absorber according to claim 1, characterized in that: The valve body (1) is integrally formed and includes an annular end (15) and a sealing end (16) disposed at one end thereon. The valve hole (12) is opened on the outer circumferential surface of the annular end (15). The sealing end (16) is provided with a large diameter end (17) and a small diameter end (18) that are recessed inward in sequence. The helical spring (31) is sleeved on the small diameter end (18) and abuts against the large diameter end (17). The small diameter end (18) is provided with a groove (19). A pilot seat (10) is fixed in the groove (19). The pilot seat (10) is provided with the liquid outlet hole (13).

3. The adjustable damping external solenoid valve for a shock absorber according to claim 2, characterized in that: The pilot seat (10) has a receiving cavity (101), the push rod (4) can extend at least partially into the receiving cavity (101), the gasket (41) abuts against the pilot seat (10), and the diameter of the gasket (41) is larger than the diameter of the receiving cavity (101).

4. The adjustable damping external solenoid valve for a shock absorber according to claim 3, characterized in that: The push rod (4) is integrally formed, including a cylindrical end (42) and a frustum end (43) disposed at one end of the cylindrical end (42). The gasket (41) is sleeved on the frustum end (43) and abuts against the cylindrical end (42). A push rod retaining groove (44) is provided on the outer circumferential surface of the frustum end (43). A push rod retaining spring (45) adapted to it is built into the push rod retaining groove (44). The outer circumferential surface of the push rod retaining spring (45) abuts against the gasket (41).

5. The adjustable damping external solenoid valve for a shock absorber according to claim 4, characterized in that: The valve body (1), valve plate (6) and valve disc (7) are all provided with openings (9) on their outer circumferential surfaces, and the gap between the openings (9) and the housing (5) forms the flow channel (14).

6. The adjustable damping external solenoid valve for a shock absorber according to claim 5, characterized in that: The valve plate (7) is integrally formed and includes a fixed end (72) fixed on the housing (5). The fixed end (72) is sleeved on the floating end (71). Both the fixed end (72) and the floating end (71) are annular. A protrusion I (73) is fixed on the inner wall of the fixed end (72), and a protrusion II (74) is fixed on the outer wall of the floating end (71). An arc-shaped connecting piece (75) is provided between the protrusion I (73) and the protrusion II (74).

7. The adjustable damping external solenoid valve for a shock absorber according to claim 6, characterized in that: The push rod (4) is fitted with a leaf spring (46) and a stop plug (47). The stop plug (47) is fixed on the housing (5). One end of the leaf spring (46) abuts against the stop plug (47), and the other end abuts against the floating end (71).

8. The adjustable damping external solenoid valve for a shock absorber according to claim 7, characterized in that: The housing (5) has a sliding cavity (52) inside, and an armature (53) is provided inside the sliding cavity (52). The push rod (4) is fixed on the armature (53), and an armature spring (57) is sleeved on the push rod (4). One end of the armature spring (57) abuts against the armature (53), and the other end abuts against the stop plug (47). One end of the armature (53) is provided with a fixed iron core (54) fixed on the housing (5). A coil frame (55) is sleeved on the outside of the armature (53), and a coil (56) is wound on the coil frame (55).

9. The adjustable damping external solenoid valve for a shock absorber according to claim 8, characterized in that: The push rod (4) is fitted with bearing sleeves (40) on both sides, and the bearing sleeves (40) are fixed on the stop plug (47) and the housing (5) respectively.

10. The adjustable damping external solenoid valve for a shock absorber according to claim 9, characterized in that: The housing (5) is assembled from an outer shell (58) and an inner shell (59). The outer shell (58) and the inner shell (59) cooperate to clamp the coil frame (55). The outer shell (58) and the inner shell (59) are provided with positioning spring grooves (50), and the positioning spring grooves (50) are provided with positioning springs (501) that are compatible with them.

Images