solenoid

Abstract

To provide a solenoid that is miniaturized while improving the waterproofness of the bobbin and casing. [Solution] The solenoid 1 of the present invention comprises a bobbin 20 composed of a cylindrical portion 201 and a large-diameter portion 202 extending radially outward from the axial end of the cylindrical portion 201; a coil 21 wound around the cylindrical portion 201 of the bobbin 20; an outer casing 22 that covers the outer circumference of the coil 21 and the outer circumference of the large-diameter portion 202 and forms a seal portion 25 between it and the large-diameter portion 202; and an injection portion 23 formed on the surface of the outer casing 22, which becomes an injection mark of the mold resin constituting the outer casing 22. The large-diameter portion 202 includes a shape-changing portion 203 in which the axial thickness is set to be thicker in some parts, including the portion furthest from the injection portion 23, than in other parts.

Description

[Technical Field]

[0001] This invention relates to a solenoid used for opening and closing a control valve of a buffer. [Background technology]

[0002] Automobile and other vehicle suspension systems are equipped with damping force adjustable shock absorbers, which adjust the damping force by opening and closing a control valve. A solenoid is used to open and close the control valve. The coil used in the solenoid is molded with molded resin for waterproofing, forming a molded coil. In the solenoid, the current flowing through the molded coil magnetizes the housing, yoke, and armature that constitute the magnetic circuit, generating an attractive force between the axially movable armature and the anchor fixed to the end of the molded coil. This imparts thrust to the valve body of the control valve via a rod fixed integrally with the armature.

[0003] Solenoids used in automotive shock absorbers are installed close to the ground and exposed to the elements. If water enters the molded coil, the electrical resistance of the coil changes, causing the solenoid to malfunction. Therefore, ensuring the waterproofness of the molded coil is a challenge in solenoid design.

[0004] As a means of solving this problem, Patent Document 1 discloses a structure in which an O-ring is provided on the upstream side of the solenoid bobbin to seal it. Patent Document 2 also discloses a structure in which protrusions with thin walls are formed on both ends of the coil bobbin, and the molding resin and the coil bobbin are heat-welded together to seal them during molding. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5463684 [Patent Document 2] Japanese Patent Application Publication No. 9-63835 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Patent Document 1 has a problem in that it forms an O-ring groove to house the O-ring, which increases the axial length of the core, and as a result increases the overall axial length of the control valve.

[0007] Furthermore, Patent Document 2 describes a structure in which a protrusion on the end face of the coil bobbin is melted in order to seal the gap between the coil bobbin and the outer casing made of molded resin without using an O-ring. However, in Patent Document 2, as the molded resin moves, heat is transferred to the mold and the coil bobbin, so the temperature of the molded resin becomes lower at a position away from the injection port, leaving an unmelted portion, which results in poor waterproofing between the coil bobbin and the outer casing.

[0008] The objective of the present invention is to provide a solenoid that is miniaturized while improving the waterproofness of the bobbin and outer casing. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a solenoid for use in a control valve, comprising: a bobbin composed of a cylindrical portion and a large-diameter portion extending radially outward from the axial end of the cylindrical portion; a coil wound around the cylindrical portion of the bobbin; an outer casing covering the outer circumference of the coil and the outer circumference of the large-diameter portion, forming a seal portion between the outer casing and the large-diameter portion; and an injection portion formed on the surface of the outer casing, which becomes an injection mark of the mold resin constituting the outer casing, wherein the large-diameter portion is provided with a shape-changing portion in which the axial thickness is set to be thicker in a part including the part furthest from the injection portion than in other parts. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a solenoid that is miniaturized while improving the waterproofness of the bobbin and outer casing. [Brief explanation of the drawing]

[0011] [Figure 1] It is a longitudinal sectional view of solenoid 1. [Figure 2] It is a longitudinal sectional view of the mold coil 2 according to an embodiment of the present invention. [Figure 3] It is a top view of the bobbin 20 according to Embodiment 1 of the present invention as seen from above. [Figure 4] It is an external perspective view of the bobbin 20 according to Embodiment 1 of the present invention. [Figure 5] It is an external perspective view after overmolding the bobbin 20 in FIG. 4. [Figure 6] It is a sectional view taken along line VI-VI in FIG. 5. [Figure 7] It is a top view of the bobbin 20 according to Modification 1 as seen from above. [Figure 8] It is an external perspective view of the bobbin 20 according to Modification 1. [Figure 9] It is an external perspective view after overmolding the bobbin 20 in FIG. 8. [Figure 10] It is a sectional view taken along line X-X in FIG. 9. [Figure 11] It is a sectional view taken along line XI-XI in FIG. 10. [Figure 12] It is a top view of the bobbin 20 according to Modification 2 as seen from above. [Figure 13] It is an external perspective view of the bobbin 20 according to Modification 2. [Figure 14] It is an external perspective view after overmolding the bobbin 20 in FIG. 13. [Figure 15] It is a sectional view taken along line XV-XV in FIG. 14. [Figure 16] It is a top view of the bobbin 20 according to Embodiment 2 of the present invention as seen from above. [Figure 17] It is a top view of the bobbin 20 according to Embodiment 3 of the present invention as seen from above. [Figure 18] It is an external perspective view of the bobbin 20 according to Embodiment 3 of the present invention. [Figure 19] It is an external perspective view after overmolding the bobbin 20 in FIG. 18. [Figure 20] This is a cross-sectional view taken along the line XX-XX in Figure 19. [Figure 21] This is a magnified view of the shape-changing section 203 and the other parts. [Modes for carrying out the invention]

[0012] The embodiments of the present invention will be described below with reference to the drawings. In principle, the same reference numerals are used for the same elements in all the drawings. Furthermore, descriptions of parts having the same function will be omitted. It should be noted that the configurations described below are merely embodiments, and it is not intended that the embodiments of the present invention are limited to the following specific embodiments. [Examples]

[0013] In the embodiment shown below, for convenience, the upper part of the paper is defined as "top" and the lower part of the paper is defined as "bottom". Also in this embodiment, the direction along the rod 8 is defined as the "axial direction", the rotational direction centered on this axial direction is defined as the "circumferential direction", and the direction perpendicular to the axial direction is defined as the "radial direction".

[0014] <Structure of a solenoid> Figure 1 is a longitudinal cross-sectional view of solenoid 1. Solenoid 1 is used to open and close a control valve of a damping force adjustable shock absorber installed in the suspension system of a vehicle such as an automobile. 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, a bush 9, and a plate 10. C in the figure indicates the center line.

[0015] The yoke 3 is formed in a cylindrical shape from a magnetic material and is positioned to surround the molded coil 2. The housing 4 is made of a magnetic material and is located on the inner circumference of the molded coil 2, positioned to cover one axial side of the armature 6. The cylinder 5 is formed in a cylindrical shape from a non-magnetic material and is positioned to extend axially from the upper surface of the bottom side of the yoke 3. The armature 6 is made of a magnetic material and is fixed to the rod 8. The anchor 7 is formed in a cylindrical shape from a magnetic material and is located radially inward from the molded coil 2, positioned to cover the other axial side of the armature 6. A through hole is formed in the center of the anchor 7, communicating in the vertical (axial) direction, and the rod 8 is inserted into this through hole. A bush 9 is positioned below the through hole of the anchor 7.

[0016] 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 located at the end of the molded coil 2 and the armature 6. A rod 8 is fixed to the center of the armature 6 and is held axially movably via a bush 9. When an attractive force is generated between the armature 6 and the anchor 7, the rod 8 imparts thrust to the valve body of the control valve.

[0017] <Basic structure of the molded coil in this embodiment> Figure 2 is a longitudinal cross-sectional view of a molded coil 2 according to an embodiment of the present invention. As shown in Figure 2, the molded coil 2 comprises a bobbin 20 composed of a cylindrical portion 201 and large-diameter portions 202 that extend radially outward from the axial ends (both axial ends in this embodiment) of the cylindrical portion 201 and have a larger diameter than the cylindrical portion 201; an insulating coated coil 21 wound around the cylindrical portion 201 of the bobbin 20; an outer casing 22 that covers the outer circumference of the coil 21 and the outer circumference of the large-diameter portions 202 of the bobbin 20 with molded resin; and an injection portion 23 formed on the surface of the outer casing 22 with a rough surface roughness.

[0018] A portion of the large-diameter section 202 (one side in Figure 2) is provided with a connecting section 24 that extends radially outward from the large-diameter section 202 and connects to the coil 21 and an external terminal. The large-diameter section 202 and the connecting section are formed continuously and integrally.

[0019] A seal portion 25 is formed between the outer casing 22 and the large-diameter portion 202 of the bobbin 20, and the seal portion 25 is located on the end face or side of the large-diameter portion 202. The outer casing 22 is formed by overmolding the bobbin 20 around which the coil 21 is wound with molding resin. In other words, the molded coil 2 is formed by overmolding the bobbin 20 around which the coil 21 is wound with molding resin.

[0020] The injection portion 23 formed on the surface of the outer casing 22 is the injection mark of the molten mold resin that makes up the outer casing 22. The seal portion 25 is formed by the melting of the interface between the outer casing 22 and the bobbin 20.

[0021] <Structure of the large-diameter section in the first embodiment> Figure 3 is a top view of the bobbin 20 according to Embodiment 1 of the present invention, viewed from above. Figure 4 is an external perspective view of the bobbin 20 according to Embodiment 1 of the present invention. Figure 5 is an external perspective view of the bobbin 20 of Figure 4 after overmolding. Figure 6 is a cross-sectional view taken along line VI-VI of Figure 5. The triangles in Figures 3 and 4 indicate the injection section 23 (injection position) for the mold resin.

[0022] As shown in Figures 3 and 4, a shape-changing portion 203 is formed on a part of the large-diameter portion 202 of the bobbin 20, protruding upward from the surface (upper surface) of the large-diameter portion 202. The shape-changing portion 203 is formed so that a part of it protrudes from the circumferential surface of the large-diameter portion 202.

[0023] In this embodiment, the shape-changing section 203 is located on the opposite side of the molding resin injection section 23 with respect to the axial direction (vertical direction). In other words, the shape-changing section 203 is located at the position furthest from the injection section 23 in the radial direction.

[0024] In this embodiment, the large-diameter portion 202 includes a shape-changing portion 203 in a part that includes the portion furthest from the injection portion 23, and the shape-changing portion 203 has a thicker axial thickness at a predetermined radial position of the large-diameter portion 202 than other parts.

[0025] Furthermore, the shape-changing portion 203 in this embodiment is connected to the connecting portion 24. That is, the connecting portion 24 is formed on the radially outer extension of the shape-changing portion 203.

[0026] Since the terminal wires of the coil 21 are positioned at two locations near the side surface of the connection portion 24, the side surface of the connection portion 24 is a thick-walled portion that is thicker in the vertical direction than the large-diameter portion 202. The upper surface of the shape-changing portion 203 that is connected to the connection portion 24 is formed flush with the upper surface (surface) of the connection portion 24. In this embodiment, the connection portion 24 also serves as the shape-changing portion 203. As a result, when viewed from the side, the connection portion 24 and the shape-changing portion 203 are thick-walled portions that are thicker in the vertical direction than the large-diameter portion 202. In other words, when viewed from the side, the large-diameter portion 202 excluding the shape-changing portion 203 is a thin-walled portion that is thinner in the vertical direction than the connection portion 24 and the shape-changing portion 203.

[0027] In this embodiment, the shape-changing section 203 is located on the opposite side of the molding resin injection section 23 with respect to the axial direction (vertical direction). In other words, the shape-changing section 203 is located at the position furthest from the injection section 23 in the radial direction.

[0028] In manufacturing the molded coil 2, a molding die is attached to cover the outer circumference of the bobbin 20 around which the coil 21 is wound. Molding resin (resin) is then injected into the molding die from the injection section 23 to overmolde the bobbin 20. After that, the molding die is removed and the overmolded molded coil 2 is taken out. The molded coil 2 removed from the molding die will look like Figure 5.

[0029] The temperature of the mold resin injected into the molding die is highest near the injection section 23 and tends to decrease as it moves away from the injection section 23. This is because the mold resin injected into the molding die loses heat due to contact with the molding die and the bobbin 20. As a result, the temperature of the mold resin decreases at positions away from the injection section 23, leaving unmelted areas in the mold resin, which leads to a problem of poor waterproofing function with respect to the bobbin 20. To improve the waterproofing function at positions away from the injection section 23, it is necessary to suppress the decrease in the temperature of the mold resin at positions away from the injection section 23 and suppress the unmelted areas of the mold resin.

[0030] The temperature of the mold resin injected into the molding die tends to be lower in the area in contact with the molding die and bobbin 20, and higher in the central area, which is further away from the die and bobbin 20. In other words, the decrease in the temperature of the mold resin can be suppressed by increasing the cross-sectional area of ​​the flow path through which the mold resin flows. This embodiment focuses on this point.

[0031] In this embodiment, as shown in Figure 6, by setting the thickness of the shape-changing section 203 at a predetermined radial position to be thicker than other parts, the flow path of the outer casing 22 during overmolding becomes wider than the shape-changing section 203, thereby improving the heat retention of the outer casing 22 until it reaches the shape-changing section 203.

[0032] Furthermore, the mold resin constituting the outer casing 22 experiences a decrease in surface temperature due to contact between the bobbin 20 and the molding die during overmolding, with the temperature being highest near the center. Because the shape-changing portion 203 is thicker than other parts, when the outer casing 22 reaches the shape-changing portion 203, the flow on the surface side of the outer casing 22 is interrupted, causing the high-temperature portion of the outer casing 22 away from the surface to flow and come into contact with the surface of the large-diameter portion 202 in the shape-changing portion 203. As a result, the surface temperature of the large-diameter portion 202 becomes high at the location where the shape-changing portion 203 is positioned.

[0033] According to this embodiment, by positioning the shape-changing portion 203 in a location that includes the position furthest from the injection portion 23, the surface temperature of the large-diameter portion 202 can be increased at the position where the temperature of the outer casing is lowest and where unmelted portions are likely to remain on the surface of the large-diameter portion 202, thereby more reliably melting the surface of the large-diameter portion 202. As a result, the interface between the outer casing and the large-diameter portion can be strongly sealed around the entire circumference of the large-diameter portion 202, and the waterproof function of the solenoid is enhanced. In particular, sufficient waterproof function can be ensured even at the sealing portion 25 located at the end face or side surface of the large-diameter portion 202.

[0034] [Variation 1] Next, a modified example 1 of Example 1 will be described using Figures 7 to 11. Figure 7 is a top view of the bobbin 20 according to Modified Example 1, seen from above. Figure 8 is an external perspective view of the bobbin 20 according to Modified Example 1. Figure 9 is an external perspective view of the bobbin 20 of Figure 8 after overmolding. Figure 10 is a cross-sectional view taken along line XX of Figure 9. Figure 11 is a cross-sectional view taken along line XI-XI of Figure 10. Components similar to those in Example 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0035] In the modified example 1, the shape-changing portion 203 is located on the opposite side of the connection portion 24, and a part of the molding resin injection portion 23 is provided at the location of the connection portion 24.

[0036] In the modified example 1, the bobbin 20 has a groove 24a formed in the center of the connecting portion 24, recessed from the upper surface (front surface) of the connecting portion 24. The groove 24a is a thin-walled portion with a thin thickness in the vertical direction (axial direction), while the weir portions 24b formed on both sides of the groove 24a are thick-walled portions with a greater thickness in the vertical direction than the groove 24a. The terminal wires of the coil 21 are placed in the weir portions 24b, which are the thick-walled portions.

[0037] Furthermore, the large-diameter portion 202 comprises an inner circumference portion 202a and an outer circumference portion 202b located radially outside the inner circumference portion 202a. The inner circumference portion 202a is a thin-walled portion with a thin thickness in the vertical direction (axial direction), while the outer circumference portion 202b of the large-diameter portion 202 is a thick-walled portion with a greater thickness in the vertical direction (axial direction) than the inner circumference portion 202a.

[0038] The groove 24a of the connecting portion 24 communicates with the inner circumference 202a of the large diameter portion 202, and a shape-changing portion 203 is formed at the end of the inner circumference 202a located on the radially opposite side of the connecting portion 24. As shown in Figure 11, the shape-changing portion 203 has a stepped shape in the large diameter portion 202.

[0039] A portion of the mold resin injected from the molding die is injected towards the groove 24a. The mold resin injected from the groove 24a flows towards the inner circumference 202a and reaches the opposite side of the injection section 23. The injection section 23 is provided on the surface of the outer casing 22 located on the radially outer extension of the groove 24a. Since the flow velocity of the mold resin flowing through the groove 24a and the inner circumference 202a is faster than in the configuration of Example 1, the mold resin can reach the opposite side of the injection section 23 while suppressing the decrease in temperature of the mold resin. As a result, the interface between the outer casing and the large diameter portion can be strongly sealed around the entire circumference of the large diameter portion 202, and the waterproof function of the solenoid is enhanced.

[0040] [Variation 2] Next, a modified example 2 of Example 1 will be described using Figures 12 to 15. Figure 12 is a top view of the bobbin 20 according to Modified Example 2, viewed from above. Figure 13 is an external perspective view of the bobbin 20 according to Modified Example 2. Figure 14 is an external perspective view of the bobbin 20 of Figure 13 after overmolding. Figure 15 is a cross-sectional view taken along line XV-XV in Figure 14. Components similar to those in Example 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0041] In modified example 2, the position of the shape-changing portion 203 is aligned with the connection portion 24.

[0042] In modified example 2, the large-diameter portion 202 comprises an inner circumference portion 202a and an outer circumference portion 202b located radially outside the inner circumference portion 202a. The inner circumference portion 202a is a thick-walled portion with a greater thickness in the vertical direction (axial direction), while the outer circumference portion 202b of the large-diameter portion 202 is a thin-walled portion with a thinner thickness in the vertical direction (axial direction) than the inner circumference portion 202a.

[0043] The outer circumference 202b is provided with a shape-changing portion 203 that is thicker in the axial direction than the outer circumference 202b, and the shape-changing portion 203 is connected to the inner circumference 202a and the connecting portion 24 of the large-diameter portion 202. The upper surface of the shape-changing portion 203 is flush with the upper surface of the connecting portion 24 and the upper surface of the inner circumference 202a of the large-diameter portion 202.

[0044] The molding resin is injected from the radially opposite side of the connection portion 24. A portion of the molding resin injected from the groove portion 24a flows along the outer circumference portion 202b and reaches the connection portion 24 side, which is the opposite side of the injection portion 23. The flow path of the molding resin flowing along the outer circumference portion 202b is narrower and the flow velocity is faster compared to the configuration of Example 1, so the molding resin can reach the connection portion 24 side, which is the opposite side of the injection portion 23, while suppressing the decrease in temperature of the molding resin. Furthermore, in Modification 2, the amount of molding resin injected to constitute the outer casing 22 is reduced, shortening the molding time in the overmolding process and suppressing the decrease in temperature of the molding resin. As a result, the interface between the outer casing 22 and the large diameter portion can be strongly sealed around the entire circumference of the large diameter portion 202, and the waterproof function of the solenoid is enhanced.

[0045] In Example 1 and Modifications 1 and 2, two injection sections 23 for the mold resin are provided in the height direction and are positioned at the same height as the large-diameter section 202. The injection sections 23 do not necessarily have to be two; configurations with three or more injection sections in the height direction or with only one injection section are also acceptable. However, if too many injection sections 23 are provided, the weld lines created by the assembly of the outer casing 22 during overmolding can cause a decrease in strength, so it is desirable to limit the number of injection sections 23 to two or less. Furthermore, in order to ensure uniform flow of the outer casing 22 during overmolding in the vertical direction of the bobbin 20, it is desirable to arrange the injection sections 23 symmetrically in the vertical direction.

[0046] <Effects of Example 1> Focusing on a bobbin 20 having a cylindrical portion 201 with a height of 12.5 mm, the surface temperature of the large-diameter portion 202 when the mold resin constituting the outer casing 22 reaches the opposite side of the injection portion 23 was determined by thermal fluid analysis for both a bobbin 20 without a shape-changing portion 203 in the large-diameter portion 202 and a bobbin 20 with a shape-changing portion 203 in the large-diameter portion 202. For the bobbin 20 with a shape-changing portion 203 in the large-diameter portion 202, the modified version 2 was used, and the outer circumference 202b of the large-diameter portion 202 was made 2 mm thinner than the inner circumference 202a and the connecting portion 24.

[0047] In the case where the outer periphery of the large-diameter portion 202 is thinned except for the connecting portion 24, the surface temperature of the large-diameter portion 202 when the outer casing 22 reaches the opposite side of the injection portion 23 is 8°C higher than in the case where there is no shape-changing portion 203 on the large-diameter portion 202, and the large-diameter portion 202 can be heated to a high temperature at the position furthest from the injection portion 23.

[0048] Furthermore, because the shape-changing section 203 has a smaller thickness at a predetermined radial position than other parts, the flow path of the outer casing 22 becomes narrower. As a result, the temperature drop of the outer casing 22 when flowing through the shape-changing section 203 is greater than that of other parts, and the circumferential length of the shape-changing section 203 must be set so that the temperature of the outer casing 22 is higher when it reaches the position furthest from the injection section 23 compared to a configuration without the shape-changing section 203.

[0049] The circumferential length of the shape-changing section 203 can be set by determining the amount of temperature drop when the outer casing 22 reaches the position furthest from the injection section 23 using thermal fluid analysis, for example, a configuration without the shape-changing section 203 and a configuration in which the circumferential length of the shape-changing section 203 is varied in multiple patterns, and then selecting the circumferential length that results in the smallest temperature drop when the outer casing 22 reaches the position furthest from the injection section 23, compared to the configuration without the shape-changing section 203.

[0050] Alternatively, without performing the analysis, for example, the integrated value Q of the heat transfer amount from the exterior body 22 to the bobbin 20 and the molding die during overmolding may be obtained, and the circumferential length of the shape change portion 203 may be determined such that the integrated value Q of the heat transfer amount exceeds the configuration without the shape change portion 203. The integrated value Q of the heat transfer amount is obtained, for example, by performing a theoretical calculation calculated from the heat transfer amount q. The integrated value Q of the heat transfer amount is the amount of heat lost by the mold resin (resin). Hereinafter, the logical calculation will be described.

[0051] The heat transfer amount q can be obtained by the following Equation 1 according to the shape of the flow path of the exterior body 22.

[0052] q=(T bobbin -T die ) / R die +(T mold -T bobbin ) / R bobbin …(Equation 1) Here, T mold is the temperature of the exterior body 22, T die is the temperature of the molding die, T bobbin is the temperature of the bobbin 20. R die and R bobbin are the thermal resistances between the molding die and the bobbin 20, respectively. The narrower the flow path of the exterior body 22, the smaller the thermal resistance R die of the molding die and the thermal resistance R bobbin of the bobbin 20 become.

[0053] The thermal resistance R die of the molding die and the thermal resistance R bobbin of the bobbin 20 are equal and can be obtained by the following Equation 2.

[0054] R die =R bobbin =h / (S×λ mold ) …(Equation 2) Here, h is the thickness of the flow path, S is the contact area, and λ mold is the thermal conductivity of the mold resin.

[0055] The integrated value Q of the heat transfer amount can be obtained by the following Equation 3. <000027​​Q = ΣqΔt ≈ q n t n +q v t v …(Formula 3) Here, q n This is the amount of heat transfer other than the shape-changing part 203, q v is the amount of heat transfer in the shape-changing section 203, t n This is the time spent passing through areas other than the shape-changing section 203, t v This represents the time it takes to pass through the shape-changing section 203.

[0057] Furthermore, the integrated value Q of the heat transfer can also be calculated using the following equation 4.

[0058] Q = ΣqΔt ≈ (q n l n +q v l v ) / V mold …(Formula 4) Here, V mold This is the flow velocity of the molding resin (assuming it is constant), l n l is the length other than the shape change part. v This is the length of the shape-changing portion 203.

[0059] Then, from the relationship between equations 3 and 4, the length l of the shape-changing portion 203 v It is possible to find this. [Examples]

[0060] Next, Embodiment 2 of the present invention will be described with reference to Figure 16. Figure 16 is a top view of the bobbin 20 according to Embodiment 2 of the present invention, viewed from above.

[0061] The large-diameter section 202 is provided with two shape-changing sections 203 located on a center line P passing through the radial center of the bobbin 20, at points symmetrical with respect to the central axis of the bobbin 20, and having a thickness in the axial direction that is greater than that of the other sections (large-diameter section 202). One of the shape-changing sections 203 is connected to a connecting section 24, and the connecting section 24 has a thickness in the axial direction that is greater than that of the large-diameter section 202. In other words, the connecting section 24, together with the other shape-changing section 203, also functions as a shape-changing section 203.

[0062] The injection sections 23 are positioned on orthogonal lines P' that are radially perpendicular to the center line P, and are located at points symmetrical with respect to the central axis of the bobbin 20.

[0063] Each injection section 23, which is positioned point-symmetrically with respect to the central axis of the bobbin 20, is located at the furthest point from the shape-changing section 203 and the connecting section 24, which also serves as the shape-changing section 203.

[0064] In this embodiment, an example is shown in which the injection section 23 is arranged in two locations in the circumferential direction, but it is also possible to arrange it in three or more locations in the circumferential direction. In that case as well, the thickened portion of the large-diameter section 202 (connecting section 24 and shape-changing section 203) is placed at the position furthest from the injection section 23.

[0065] In this embodiment, the injection section 23 is arranged symmetrically in a direction perpendicular (90 degrees) to the center line P passing through the radial center of the bobbin 20. This shortens the time it takes for the large-diameter section 202 injected from the injection section 23 to reach the thicker sections (connection section 24 and shape-changing section 203), thereby suppressing the temperature drop of the molded resin. As a result, the interface between the outer casing 22 and the large-diameter section 202 can be strongly sealed around its entire circumference, enhancing the waterproof function of the solenoid. [Examples]

[0066] Next, Embodiment 3 of the present invention will be described using Figures 17 to 21. Figure 17 is a top view of the bobbin 20 according to Embodiment 3 of the present invention, viewed from above. Figure 18 is an external perspective view of the bobbin 20 according to Embodiment 3 of the present invention. Figure 19 is an external perspective view of the bobbin 20 of Figure 18 after overmolding. Figure 20 is a cross-sectional view taken along line XX-XX in Figure 19. Figure 21 is an enlarged view of the shape-changing portion 203 and the other parts. Figure 21(a) shows the shape-changing portion 203, and Figure 21(b) shows the parts other than the shape-changing portion 203. Components similar to those in Embodiment 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0067] In Figures 17 and 18, the large-diameter portions 202 are not continuous with the connecting portions 24 and are thin-walled. The outer circumference of the large-diameter portions 202 is tapered. In this embodiment, a shape-changing portion 203 is provided in which a part of the large-diameter portion 202 has a taper angle θ that is larger than the taper angle θ of other large-diameter portions 202.

[0068] In the shape-changing section 203, the taper angle θ of the outer circumference is larger than that of the other parts, and the axial thickness AT at a predetermined radial position RL is set to be thicker than that of the other parts.

[0069] According to this embodiment, since the taper angle θ of the outer circumference is made different between the shape-changing portion 203 and the other portions, in addition to the effects of embodiments 1 and 2, the shape of the bobbin 20 can be simplified.

[0070] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0071] 1...Solenoid, 2...Molded coil, 3...Yoke, 4...Housing, 5...Cylinder, 6...Armature, 7...Anchor, 8...Rod, 9...Bush, 10...Plate, 20...Bobbin, 21...Coil, 22...Outsole, 23...Injection section, 24...Connection section, 24a...Groove section, 24b...Weir section, 25...Seal section, 201...Cylindrical section, 202...Large diameter section, 202a...Inner circumference section, 202b...Outer circumference section, 203...Shape change section

Claims

1. A solenoid used in a control valve, A bobbin comprising a cylindrical portion and a large-diameter portion extending radially outward from the axial end of the cylindrical portion, The coil wound around the cylindrical portion of the bobbin, An outer casing that covers the outer circumference of the coil and the outer circumference of the large diameter portion, and that forms a sealing portion between itself and the large diameter portion, The exterior body comprises an injection portion formed on its surface, which serves as an injection mark for the mold resin constituting the exterior body, The solenoid is characterized in that the large-diameter portion includes a shape-changing portion in which the axial thickness is set to be thicker in a part including the part furthest from the injection portion than in other parts.

2. A solenoid according to claim 1, The solenoid is characterized in that the shape-changing portion has a stepped shape.

3. A solenoid according to claim 1, It includes a connection part for connecting the coil and an external terminal, A solenoid characterized in that the connection portion is connected to the shape-changing portion.

4. The solenoid according to claim 3, The solenoid is characterized in that the connecting portion is located radially outward from the shape-changing portion and is formed flush with the surface of the shape-changing portion.

5. A solenoid according to claim 1, The solenoid is characterized in that the injection portion is provided in multiple locations along the axial direction of the outer casing.

6. A solenoid according to claim 1, The large-diameter portion comprises an inner circumferential portion and an outer circumferential portion located radially outside the inner circumferential portion and having a greater thickness in the axial direction than the inner circumferential portion. The solenoid is characterized in that the inner circumference portion is provided with the shape-changing portion, which has a greater thickness in the axial direction than the inner circumference portion.

7. The solenoid according to claim 6, The radially outer side of the large-diameter portion is provided with a connection portion for connecting the coil and the external terminal. The connecting portion comprises a groove formed in the central part and recessed from the surface of the connecting portion, and a weir formed so as to sandwich the groove and having a greater axial thickness than the groove. The solenoid is characterized in that the groove portion communicates with the inner circumference portion of the large diameter portion, and the injection portion is provided on the surface of the outer casing located on the radially outer extension of the groove portion.

8. A solenoid according to claim 1, The large-diameter portion comprises an inner circumferential portion and an outer circumferential portion located radially outside the inner circumferential portion and having a thinner thickness in the axial direction than the inner circumferential portion. The solenoid is characterized in that the outer circumference is provided with the shape-changing portion, which has a greater thickness in the axial direction than the outer circumference.

9. The solenoid according to claim 8, It includes a connection part for connecting the coil and an external terminal, A solenoid characterized in that the connection portion is connected to the shape-changing portion.

10. A solenoid according to claim 1, The large-diameter portion is provided with two shape-changing sections located on the center line passing through the radial center of the bobbin, at points symmetrical with respect to the central axis of the bobbin. The solenoid is characterized in that the injection portion is positioned on a line perpendicular to the center line in the radial direction and at a point symmetrical position with respect to the central axis of the bobbin.

11. A solenoid according to claim 10, It includes a connection part for connecting the coil and an external terminal, The solenoid is characterized in that the connecting portion has a thickness in the axial direction greater than that of the large-diameter portion and is connected to one of the two shape-changing portions.

12. A solenoid according to claim 1, The outer circumference of the large diameter portion is formed in a tapered shape. The shape-changing portion is provided in which a taper angle is formed in a part of the large-diameter portion to be larger than the taper angle with respect to other large-diameter portions. A solenoid characterized in that the axial thickness of the shape-changing portion at a predetermined radial position is set to be thicker than that of other portions.

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