Solenoid, shock absorber, and solenoid manufacturing method

Abstract

The purpose of the present invention is to provide a solenoid structure capable of shortening the axial length. This solenoid is provided with: a bobbin (20) having a tube section (201) and a large-diameter section (202) formed at one end of the tube section (201) and extending outward in the radial direction of the tube section (201); a coil (21) wound around the cylindrical portion (201) of the bobbin (20); and a primary package (22) that covers the outer periphery of the coil (21) and the side surface (202a) of the large-diameter section (202) of the bobbin (20), and forms a sealing section (23) between the primary package (22) and the side surface (202a) of the large-diameter section (202) of the bobbin (20). At least a portion of an end surface (2022) of the large-diameter portion (202), the end surface (2022) being on the opposite side of the winding side of the coil (21), of the two end surfaces (2021, 2022) is exposed from the primary package (22).

Description

Technical Field

[0001] The present invention relates to a solenoid included in a solenoid valve, a damper, and a method for manufacturing the solenoid. Background Art

[0002] Patent document 1 describes a molded coil in which a coil is wound between frame circular plates arranged near the two ends of a cylindrical coil winding tube made of thermoplastic resin, and a protrusion is formed on the outer side surface and outer peripheral surface of the frame circular plate that is continuous in the circumferential direction and has a thin-walled portion at the top. By injection molding a molten high-temperature resin of a molding material made of the same resin into the outer peripheral portion of the coil winding tube, the thin-walled portion is heated and melted by the molding material, and the two are heat-fused into one (see the summary). Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 9-63835 Summary of the Invention Problems to be solved by the invention

[0004] In the molded coil of Patent Document 1, since the protrusions provided on the end face of the coil bobbin are melted, it is necessary to inject molding material into the end face of the coil bobbin. The molding material on the end face of the coil bobbin increases the axial length of the coil.

[0005] An object of the present invention is to provide a solenoid structure capable of shortening the axial length. Technical means to solve the problem

[0006] In order to achieve the above object, the solenoid of the present invention is a solenoid installed on a solenoid valve. The solenoid has: a bobbin having a cylindrical portion and a large-diameter portion formed at one end of the cylindrical portion and extending radially outward from the cylindrical portion; a coil wound around the cylindrical portion of the bobbin; and a primary package covering the outer periphery of the coil and the side surface of the large diameter portion of the bobbin, forming a sealing portion between the primary package and the side surface of the large diameter portion of the bobbin; At least a portion of an end surface on the opposite side to the winding side of the coil among both end surfaces of the large-diameter portion is exposed from the primary package. Effects of the Invention

[0007] According to the present invention, by providing a seal portion on the side of the large diameter portion of the bobbin and omitting the seal portion on the end surface of the large diameter portion, the axial length of the solenoid can be shortened. By shortening the axial length of the solenoid, the buffer can be miniaturized. Problems, structures, and effects other than those described above will become clear from the description of the following embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a longitudinal sectional view of a solenoid according to an embodiment of the present invention. Figure 2 It is from Figure 1 A longitudinal cross-sectional view of a solenoid with the molded coil removed for display. Figure 3 It is near the side of the large diameter part of the molded coil ( Figure 2 An enlarged view of Part III of FIG. Figure 4 This is a diagram showing a modified example (first modified example) of the solenoid of the present invention, and is an enlarged view of the vicinity of the side surface of the large-diameter portion of the molded coil. Figure 5 This is a diagram showing a modified example (second modified example) of the solenoid of the present invention, and is an enlarged view of the vicinity of the side surface of the large-diameter portion of the molded coil. Figure 6 This is an enlarged view of the outer periphery of the molded coil. Figure 7 This is an enlarged view of the vicinity of the outer periphery of the large-diameter portion of the bobbin. Figure 8 This is an example of a longitudinal cross-sectional view of a mold for forming a primary package. Figure 9 It is a longitudinal sectional view of the shock absorber of the present invention. Figure 10 It is an enlarged view of the side surface of the large diameter portion of a molded coil in a comparative example compared with the present invention. DETAILED DESCRIPTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] First, refer to Figure 9 The damper to which the solenoid 1 of the present invention is applied will be described. Figure 9 1 is a longitudinal sectional view of the shock absorber 100 of the present invention. In this embodiment, the damping force adjustable shock absorber 100 is described as an example.

[0011] The damping force-adjustable hydraulic shock absorber (hereinafter referred to as the shock absorber) 100 of this embodiment has a double-tube structure, with an outer tube 103 provided outside a cylinder 102. A reservoir 104 is formed between the cylinder 102 and the outer tube 103. A piston 105 is slidably mounted within the cylinder 102, dividing the interior of the cylinder 102 into two chambers: an upper chamber 102A and a lower chamber 102B. One end of a piston rod 106 is connected to the piston 105 via a nut 107. The other end of the piston rod 106 passes through the upper chamber 102A and is inserted through a rod guide 108 and an oil seal 109 attached to the upper ends of the cylinder 102 and outer tube 103, extending outward from the cylinder 102. A bottom valve 110 is provided at the lower end of the cylinder 102, dividing the lower chamber 102B from the reservoir 104.

[0012] Oil passages 111 and 112 are provided on piston 105, connecting the upper and lower cylinder chambers 102A and 102B. Oil passage 111 is provided with a check valve 113, which allows oil to flow only from the lower cylinder chamber 102B to the upper cylinder chamber 102A. Oil passage 112 is also provided with a disk valve 114, which opens when the oil pressure in the upper cylinder chamber 102A reaches a specified pressure, releasing the oil from the upper cylinder chamber 102A to the lower cylinder chamber 102B.

[0013] Oil passages 115 and 116 are provided in bottom valve 110, connecting cylinder lower chamber 102B and reservoir 104. Oil passage 115 is provided with a check valve 117, which only allows oil to flow from reservoir 104 to cylinder lower chamber 102B. Oil passage 116 is provided with a disk valve 118, which opens when the pressure of the oil in cylinder lower chamber 102B reaches a specified pressure, releasing the oil from cylinder lower chamber 102B to reservoir 104. Oil is enclosed in cylinder 102, while oil and gas are enclosed in reservoir 104.

[0014] Separator tubes 120 are fitted onto the cylinder 102 at both its upper and lower ends, interposed between seal members 119. An annular oil passage 121 is formed between the cylinder 102 and separator tube 120. Annular oil passage 121 communicates with the cylinder upper chamber 102A via an oil passage 122 provided in the sidewall of the cylinder 102 near its upper end. A small-diameter opening 123 is provided in the sidewall of separator tube 120. Furthermore, a large-diameter opening 124, approximately concentric with opening 123, is provided in the sidewall of the outer cylinder 103. A damping force generating mechanism 125 is mounted in opening 124 in the sidewall of the outer cylinder 103.

[0015] The damping force-adjustable shock absorber 100 is installed, for example, in an automobile suspension system. In the damping force-adjustable shock absorber 100, a piston 105 connected to a piston rod 106 is generally slidably fitted within a cylinder 102 enclosed in oil. The cylinder 102 is divided into two chambers. The flow of oil within the cylinder 102, generated by the sliding of the piston 105, is controlled by a damping force generating mechanism 125 composed of an orifice, a disc valve, and the like to generate damping force. Furthermore, the damping force is adjusted by varying the flow resistance of the damping force generating mechanism 125 using a pressure control valve 128. The damping force generating mechanism 125 includes a solenoid 1 for controlling the pressure control valve 128, forming a solenoid valve. Hereinafter, the damping force generating mechanism 125 will be referred to as a "solenoid valve."

[0016] Hereinafter, the solenoid 1 of the present invention will be described. (Structure of Solenoid 1) Figure 1 It is a longitudinal sectional view of the solenoid 1 according to one embodiment of the present invention. In the following description, the "axial direction" is the direction along the central axis 20a of the bobbin 20, and the radial direction is the radial direction of the bobbin 20, that is, the direction perpendicular to the central axis 20a. As described later, the bobbin 20 has a cylindrical portion 201 (see Figure 2 ), the central axis 20a is the axis passing through the center of the cylindrical portion 201.

[0017] A solenoid 1 is used to open and close the pressure control valve 128 of a damping force-adjustable shock absorber 100 mounted on a suspension system of a vehicle such as an automobile. The solenoid 1 comprises a molded coil 2, a yoke 3, a housing 4, a cylinder 5, an armature 6, an anchor 7, a rod 8, and a bushing 9. Reference numeral 10 denotes a plate attached to one end of the solenoid 1. When current flows through the molded coil 2, the yoke 3, housing 4, and armature 6 become magnetized, generating an attractive force between the anchor 7 at one end of the molded coil 2 and the armature 6. A rod 8 is fixed to the center of the armature 6 and supported axially and linearly by the anchor 7 via a bushing 9. This attractive force between the armature 6 and anchor 7 applies thrust to the valve body of the pressure control valve 128 via the rod 8.

[0018] (Basic Structure of Molded Coil 2) Figure 2 It is from Figure 1 A longitudinal sectional view of a solenoid 1 showing a molded coil 2 is shown. The molded coil 2 comprises a bobbin 20 comprising a cylindrical portion 201 and a large-diameter portion 202 extending radially outward from the cylindrical portion 201; a coil 21 with an insulating covering wound around the cylindrical portion 201 of the bobbin 20; and a primary encapsulating body 22 covering the outer periphery of the coil 21 and the side surfaces 202a of the large-diameter portion 202 of the bobbin 20. A sealing portion 23 is formed between the primary encapsulating body 22 and the large-diameter portion 202 of the bobbin 20, located on the side surfaces 202a of the large-diameter portion 202. The primary encapsulating body 22 is formed by overmolding the bobbin 20 around which the coil 21 is wound, and the sealing portion 23 is formed by melting the interface between the primary encapsulating body 22 and the bobbin 20.

[0019] Figure 3 The molded coil 2 is located near the side surface 202a of the large diameter portion ( Figure 2 Hereinafter, "end face" refers to the axial end face. The axial position of the end face 221 of the primary package 22 differs from the axial position of the end face 2022 of the large diameter portion 202, which is opposite the end face 2021 connected to the cylindrical portion 201. The distance L1 between the end face 221 of the primary package 22 and the end face 2021 of the large diameter portion 202 is greater than the thickness T1 of the large diameter portion 202. In other words, the end face 221 of the primary package 22 is axially offset from the end face 2022 of the large diameter portion 202, toward the side opposite to the coil 21. In this case, the axial height H1 of the sealing portion 23 is equal to the thickness T1 of the large diameter portion 202.

[0020] In addition, the end face 2022 of the large diameter portion 202 is exposed on its entire surface. Here, the so-called "exposed" means that it is not covered by the primary package 22 and is exposed from the primary package 22. That is, Figure 1 As shown, the end face 2022 can also be covered by the yoke 3 or the plate 10 .

[0021] In addition, if Figure 1 As shown, at least a portion of the end surface 2022 is covered by other components such as the yoke 3 and the plate 10. Therefore, it is sufficient to configure the solenoid 1 so that at least a portion of the end surface 2022 is exposed from the primary package 22. This allows the axial length of the solenoid 1 to be shortened in relation to these other components. Specifically, of the two end surfaces 2021 and 2022 of the large-diameter portion 202, at least a portion of the end surface 2022 on the side opposite to the winding side of the coil 21 is exposed from the primary package 22.

[0022] Figure 4 This figure shows a modified example (first modified example) of the solenoid 1 of the present invention, and is an enlarged view of the vicinity of the large-diameter side surface 202 a of the molded coil 2 . In this example, the axial position of the end face 221 of the primary package 22 coincides with the axial position of the end face 2022 of the large diameter portion 202. At this time, the height H1 of the sealing portion 23 in the axial direction of the bobbin 20 is equal to the thickness T1 of the large diameter portion 202. Figure 3 Compared with the case of the molded coil 2, the axial length of the molded coil 2 alone can be shortened, and the axial length of the solenoid 1 can be reliably shortened.

[0023] Figure 5 This figure shows a modified example (second modified example) of the solenoid 1 of the present invention, and is an enlarged view of the vicinity of the large-diameter side surface 202 a of the molded coil 2 . In this example, the distance L1 between the end face 221 of the primary package 22 and the end face 2021 of the large-diameter portion 202 is smaller than the thickness T1 of the large-diameter portion 202. In this case, the distance L1 between the end faces 221 and 2021 corresponds to the axial height H1 of the sealing portion 23, and the height H1 of the sealing portion 23 is smaller than the thickness T1 of the large-diameter portion 202. While ensuring the sealing performance of the sealing portion 23, the distance L1 can be made smaller than the thickness T1, allowing the molded coil 2 to be miniaturized.

[0024] In the above-described embodiment and modified examples, the side surface 202a of the large diameter portion 202 of the bobbin 20 is shown as a simple cylindrical shape. However, the side surface 202a of the large diameter portion 202 does not necessarily need to be cylindrical. For example, the side surface 202a of the large diameter portion 202 may have a different shape, such as a protrusion.

[0025] like Figures 3 to 5 As shown, in the present embodiment and the modified example, the height H1 of the sealing portion 23 in the axial direction is equal to or smaller than the thickness T1 of the large diameter portion 202 .

[0026] (Structure of the outer periphery of the coil) Figure 10 It is an enlarged view of the side surface 202a of the large diameter portion of the molded coil in a comparative example compared with the present invention. In this embodiment, the sealing portion 23 of the primary package 22 and the bobbin 20 is located on the side surface 202a of the large diameter portion 202. On the other hand, in the comparative example compared with the present invention, Figure 10 As shown, the primary package 22 is also provided on the end surface 2022 of the large diameter portion, and the sealing portion 23 is formed not only on the side surface 202a of the large diameter portion 202 of the bobbin but also on the end surface 2022 of the large diameter portion. Therefore, the area of ​​the sealing portion 23 is larger than that of the present embodiment.

[0027] In this embodiment, in order to fully exert the waterproof performance through the sealing part 23, the molding temperature during the overmolding of the primary package 22 is increased than before, and the heat of the primary package 22 is used to reliably melt the resin material located on the side 202a of the large diameter part 202.

[0028] Figure 6 It is an enlarged view of the outer periphery of the molded coil 2. A protective mechanism 24 is provided between the primary package 22 and the coil 21. The protective mechanism 24 is, for example, a sheet-shaped member. Hereinafter, the protective mechanism will be referred to as a protective member or a protective portion for explanation. If the molding temperature during the overmolding of the primary package 22 is set to be lower than the melting point of the protective portion 24, the protective portion 24 will not liquefy during injection molding, thereby avoiding direct contact between the primary package 22 and the coil 21. Therefore, as the protective portion 24, a material having a melting point higher than the heat-resistant temperature of the insulating coating of the coil 21 is used.

[0029] Here, the heat-resistant temperature of the insulation coating of the coil 21 is a temperature at which the insulation performance of the coil 21 deteriorates after the primary overmolding of the package 22 , and is equal to or lower than the melting point of the insulation coating of the coil 21 . By providing the protective portion 24 between the primary package 22 and the coil 21 , the molding temperature of the primary package 22 can be set to be higher than the heat resistance temperature of the insulation coating of the coil 21 , and the primary package 22 can be molded at a higher temperature than before.

[0030] Furthermore, a material having a lower thermal conductivity than the insulating coating of coil 21 can be used for protection portion 24. This can reduce heat transferred to coil 21 through protection portion 24 during injection molding of primary package 22.

[0031] Figure 7 It is an enlarged view of the vicinity of the outer periphery of the large diameter portion 202 of the bobbin 20 . On the end face 2021 of the large diameter portion 202 of the molded coil 2, the diameter of the large diameter portion 202 is reduced, and a step (step portion) 2023 is formed on the large diameter portion 202. In the case where there is a gap between the protective portion 24 and the large diameter portion 202, there is a risk that the molten resin will flow into the outer periphery of the coil 21 during the molding of the primary package 22, and the insulating coating of the coil 21 may be damaged. However, by providing the step 2023, when the protective portion 24 is wound on the outer periphery of the coil 21, it is easy to position the protective portion 24 so that the protective portion 24 reliably covers the axial end of the winding range of the coil 21, thereby preventing the formation of a gap between the end face 2021 of the large diameter portion 202 and the protective portion 24. At this time, the large diameter portion 202 has a step 2023 on the end face 2021 on the winding side of the coil 21, and the protective portion 24 is provided so as to cover the step 2023.

[0032] exist Figure 7 In the configuration, since the protective portion 24 is wound around the small-diameter portion of the step 2023, the sealing portion 23 is not formed on the step 2023. Therefore, in order to prevent the waterproof function of the sealing portion 23 from being reduced, the height of the step 2023 is preferably minimized. Furthermore, the step 2023 is not necessarily required. For example, as long as the protective portion 24 is wound around the outer periphery of the coil 21 using a device with high positioning accuracy, the step 2023 is not necessarily required.

[0033] While this embodiment shows the use of a sheet-like member as protective portion 24, other protective mechanisms, such as a spray-applied coating or an overmolded resin layer, are also acceptable. Furthermore, while this embodiment shows the use of protective portion 24, in the case of a material with a low heat of fusion, such as syndiotactic polystyrene resin (SPS), even if the molding temperature of primary package 22 is below the heat-resistant temperature of the insulation coating of coil 21, the sealing portion 23 can still maintain sufficient waterproofing, and thus protective portion 24 may not be provided.

[0034] (Waterproof Performance of Sealing Section 23) The waterproof performance of the seal 23 in this example was verified using glass fiber-reinforced nylon resin (PA66-GF30). Using a bobbin 20 with a large diameter portion of 28 mm in diameter and 3 mm in thickness as the test object, the bobbin 20 was overmolded with a gate positioned near the side of the large diameter portion 202, ensuring a temperature of 280°C or higher when the primary package 22 reached the large diameter portion 202. The resulting molded coil 2 was then tested for leakage using a submersion test. The results confirmed that leakage was blocked within a 1 mm thick portion of the large diameter side 202a, demonstrating that even with only the seal between the primary package 20 and the bobbin 20 located on the large diameter side 202a, the necessary waterproof performance was maintained.

[0035] The finite element analysis was performed to determine the thermal conductivity of a 0.3 mm thick fluororesin sheet (0.25 Wm) wound around the outermost periphery of the bobbin 20 having a cylindrical portion 201 with a height of 12.5 mm. -1 .K -1 ) as the temperature during molding when the protective portion 24 is formed. When injection molding is performed with the gate set at half the height of the barrel 201, by setting the barrel temperature to 295°C, the temperature of the primary package 22 when it reaches the large-diameter portion 202 is between 280°C and 295°C, ensuring the waterproof performance of the sealing portion 23. Furthermore, since the melting point of the fluororesin sheet is 312°C, the protective portion 24 does not melt during injection molding, and the insulation coating of the coil 21 (heat-resistant temperature 290°C to 300°C) is not damaged.

[0036] In the manufacturing method of the solenoid 1 of the present embodiment, a protective portion 24 having a melting point higher than the heat-resistant temperature of the insulating coating of the coil 21 is provided on the outer peripheral surface of the coil 21, the primary package 22 is heated to above 280°C, and the primary package 22 is injection molded in a manner so as to cover the outer peripheral surface of the primary package 22 and the side surface 202a of the large diameter portion 202 of the winding tube 20, with the end face 2022 of the large diameter portion 202 exposed.

[0037] <Method for Manufacturing Molded Coil> Next, an example of a manufacturing process of the molded coil 2 of the solenoid 1 is shown. In this embodiment, an example of glass fiber reinforced nylon resin (for example, PA66-GF30) is shown.

[0038] Figure 8 This is an example of a longitudinal cross-sectional view of a molding die 30 for the primary package 22 . The molding die 30 includes restraining portions 301 at both ends in the axial direction, and restricts the flow of the primary package 22 in the axial direction Ax during injection molding.

[0039] Protective portion 24 is provided on the outer periphery of bobbin 20 around which coil 21 is wound before injection molding of primary package 22. After bobbin 20, coil 21, and protective portion 24 are placed inside mold 30, primary package 22 is injected through gate 302 to fill mold 30.

[0040] exist Figure 8 In FIG, an example of a case where the gate 302 is provided at one location of the mold 30 is shown. The gate 302 is preferably arranged at a position half the height of the barrel 201 to minimize the time it takes for the resin forming the primary package 22 to reach the two large diameter portions 202 in the axial direction Ax during injection molding. Figure 8 In the example shown, the heating temperature in the barrel is set to 295°C or higher so that the temperature of the primary package body 22 when it reaches the large-diameter portion 202 during injection molding is 280°C or higher. In this embodiment, a single gate 302 is provided at a position halfway up the height of the barrel 201. However, the gate 302 does not necessarily need to be provided at halfway up the height of the barrel 201, and multiple gates may be provided instead of just one.

[0041] <Effects> According to the above-described embodiment and its modified examples, the following effects can be obtained.

[0042] Since the sealing portion 23 of the molded coil 2 is located on the side surface 202a of the large diameter portion 202 of the bobbin 20, the end surface 2022 of the large diameter portion 202 is exposed. Therefore, the axial length of the molded coil 2 can be longer than Figure 10The molded coil structure of the comparative example shown in the figure is shorter than that of the present invention. Therefore, the axial lengths of the housing 4 and the anchor 6 can be shortened, the axial length of the solenoid 1 can be shortened, and the electromagnetic valve 125 of the shock absorber 100 can be miniaturized.

[0043] Furthermore, while maintaining the shapes of the housing 4 and anchor 6, the axial length of the cylindrical portion 201 of the bobbin 20 can be made longer than in the molded coil structure of the comparative example compared to the present invention. As a result, the number of turns of the coil 21 can be increased, thereby increasing the attractive force between the armature 6 and anchor 7 and the thrust of the solenoid 1.

[0044] The embodiments of the present invention described above have the following features. (1) A solenoid 1 mounted on a solenoid valve 125, Solenoid 1 has: The bobbin 20 includes a cylindrical portion 201 and a large diameter portion 202 formed at one end of the cylindrical portion 201 and extending radially outward from the cylindrical portion 201 . a coil 21 wound around the cylindrical portion 201 of the bobbin 20; and The primary package 22 covers the outer periphery of the coil 21 and the side surface 202a of the large diameter portion 202 of the bobbin 20, and forms a sealing portion 23 between the primary package 22 and the side surface 202a of the large diameter portion 202 of the bobbin 20. Of both end surfaces 2021 and 2022 of the large-diameter portion 202 , at least a portion of the end surface 2022 on the opposite side to the winding side of the coil 21 is exposed from the primary package 22 .

[0045] (2) The height H1 of the sealing portion 23 in the axial direction of the bobbin 20 is equal to or smaller than the thickness T1 of the large diameter portion 202 .

[0046] (3) Of the two end surfaces 2021 and 2022 of the large diameter portion 202 , the end surface 2022 on the opposite side to the winding side of the coil 21 is entirely exposed from the primary package 22 .

[0047] (4) The protective portion 24 is provided between the outer peripheral surface of the coil 21 and the primary package 22 , and the melting point of the protective portion 24 is higher than the heat-resistant temperature of the insulating coating of the coil 21 .

[0048] (5) The thermal conductivity of the protection portion 24 is lower than the thermal conductivity of the insulating coating of the coil 21 .

[0049] (7) The protection portion 24 is provided between the outer peripheral surface of the coil 21 and the primary package 22 , and the protection portion 24 is formed of a sheet-like member.

[0050] (7) The large diameter portion 202 has a step 2023 on the end surface 2021 on the winding side of the coil 21 , and the protection portion 24 is provided so as to cover the step 2023 .

[0051] (8) A shock absorber 100 is mounted on a suspension system of an automobile and includes a pressure control valve 128 and a solenoid for controlling the pressure control valve 128 , wherein the shock absorber 100 includes the solenoid 1 as the solenoid.

[0052] (9) A method for manufacturing a solenoid 1, wherein A protective portion 24 having a melting point higher than the heat-resistant temperature of the insulating coating of the coil 21 is provided on the outer peripheral surface of the coil 21. The primary package 22 is heated to above 280°C. The primary package 22 is injection molded so as to cover the outer peripheral surface of the primary package 22 and the side surface 202 a of the large diameter portion 202 of the bobbin 20 and to expose the end surface 2022 of the large diameter portion 202 .

[0053] (10) A method for manufacturing the solenoid 1 , wherein the thermal conductivity of the protection portion 22 is lower than the thermal conductivity of the insulating coating of the coil 21 .

[0054] In addition, the present invention is not limited to the above-mentioned embodiments. As long as the characteristics of the present invention are not impaired, other methods that are considered within the scope of the technical concept of the present invention are also included in the scope of the present invention. In addition, the present invention is not limited to the above-mentioned embodiments, and includes various modifications. For example, the above-mentioned embodiments are detailed descriptions for easy understanding of the present invention and are not necessarily limited to having all the components. In addition, for a part of the components of the embodiment, other components can be added, deleted, or replaced. Explanation of symbols

[0055] 1…solenoid, 20…bobbin, 21…coil, 22…primary package, 23…sealing portion, 24…protective portion, 100…damping force adjustable shock absorber, 125…solenoid valve, 128…pressure control valve, 201…cylinder portion, 202…large diameter portion, 202a…side surface of large diameter portion 202, 2021…end surface on the winding side of coil 21, 2022…end surface on the opposite side to the winding side of coil 21, 2023…step.

Claims

1. A solenoid mounted on a solenoid valve, characterized in that: The solenoid has: a bobbin having a cylindrical portion and a large-diameter portion formed at one end of the cylindrical portion and extending radially outward from the cylindrical portion; a coil wound on the cylindrical portion of the bobbin; as well as a primary package covering the outer periphery of the coil and the side surface of the large diameter portion of the bobbin, forming a sealing portion between the primary package and the side surface of the large diameter portion of the bobbin; At least a portion of an end surface on the opposite side to the winding side of the coil among both end surfaces of the large-diameter portion is exposed from the primary package.

2. The solenoid according to claim 1, wherein The height of the sealing portion in the axial direction of the bobbin is equal to or smaller than the thickness of the large diameter portion.

3. The solenoid according to claim 1, wherein Of both end surfaces of the large-diameter portion, the entire end surface on the side opposite to the winding side of the coil is exposed from the primary package.

4. The solenoid according to claim 1, wherein A protective portion is provided between the outer peripheral surface of the coil and the primary package. The melting point of the protection portion is higher than the heat-resistant temperature of the insulation coating of the coil.

5. The solenoid according to claim 4, wherein The thermal conductivity of the protection portion is lower than the thermal conductivity of the insulating coating.

6. The solenoid according to claim 1, wherein A protective portion is provided between the outer peripheral surface of the coil and the primary package. The protection portion is formed of a sheet-shaped member.

7. The solenoid according to claim 6, wherein The large diameter portion has a step on the end surface on the winding side of the coil. The protection portion is provided so as to cover the step.

8. A shock absorber mounted on a suspension device of an automobile, comprising a pressure control valve and a solenoid for controlling the pressure control valve, wherein: The solenoid according to claim 1 is provided as the solenoid.

9. A method for manufacturing a solenoid according to claim 1, characterized in that: A protective portion having a melting point higher than the heat-resistant temperature of the insulating coating of the coil is provided on the outer peripheral surface of the coil. The primary package is heated to above 280°C. The primary package is injection molded so as to cover the outer peripheral surface of the primary package and the side surfaces of the large-diameter portion of the bobbin and expose the end surface of the large-diameter portion.

10. The method for manufacturing a solenoid according to claim 9, wherein: The thermal conductivity of the protection portion is lower than the thermal conductivity of the insulating coating.

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