Electromagnetic relay

Abstract

Electromagnetic relay, with: a shell (10) which has a housing space (104) which is open to an exterior of the shell (10) through an opening (103); a base (12) which is connected to the shell (10) to close the opening (103); a coil (18) which is arranged in the housing space (104) to generate an electromagnetic force when the coil (18) is energized; a pair of fixed contact elements (14, 16) which are fixed to the base (12) and one end of which is arranged in the housing space (104); a movable contact element (36, 40) arranged in the housing space (104) and driven by the electromagnetic force generated by the coil (18) to touch or separate from the fixed contact elements (14, 16); and a plurality of ventilation holes (50) through which the housing space (104) is connected to the outside, wherein the ventilation holes (50) are set to a size that makes it possible to extinguish a flame passing through the ventilation holes (50), wherein the multitude of ventilation holes (50) are arranged in a section where the shell (10) and the base (12) are connected, and one of the shell (10) and the base (12) has a plurality of projections (106, 126) having pointed ends that touch the other of the shell (10) and the base (12), such that the plurality of projections (106, 126) defines the plurality of ventilation holes (50) between the shell (10) and the base (12).

Description

CROSS-REFERENCE TO A RELATED REGISTRATION

[0001] This application is based on Japanese patent application No. 2015-212057, which was filed on October 28, 2015. TECHNICAL AREA

[0002] The present invention relates to an electromagnetic relay that opens or closes an electrical circuit. STATE OF THE ART

[0003] A conventional electromagnetic relay comprises a housing containing a casing that is open to the outside through an opening, and a base attached to the housing to close the opening. The casing is connected to the outside through a ventilation hole formed in the base.

[0004] The base has a terminal insertion hole into which a terminal is inserted. The terminal insertion hole and the vent hole are adjacent to each other to ensure communication. Therefore, if a flame generated inside the housing passes through the vent hole, the base and terminal extinguish the flame by drawing heat away from it (see, for example, JP 5 131 218 B).

[0005] US 2010 / 0066471A1 discloses an electromagnetic relay with a ventilation hole. JP S47-12428Y1, US 2010 / 0193475A1, and JP 2006-59702A disclose further prior art. SUMMARY

[0006] However, the conventional electromagnetic relay may have a limitation on the position of the ventilation hole, and one degree of freedom in the design may be reduced.

[0007] From the perspective of flame extinguishing, the ventilation hole must have a width that is smaller than a predetermined dimension, while from the perspective of air passing through it, the ventilation hole must ensure a predetermined permeability area, that is, a predetermined width and length.

[0008] However, if the ventilation hole, as in a conventional electromagnetic relay, is located next to the terminal insertion hole, its length is limited by the length of the terminal insertion hole and the width of the terminal. Therefore, if the terminal width is small and the ventilation hole width is specified to be less than or equal to the predetermined flame-extinguishing dimension, ensuring the predetermined ventilation hole area becomes difficult.

[0009] Furthermore, in a conventional electromagnetic relay, the housing is only connected to the outside via the ventilation hole. Therefore, airtightness must be ensured at the point where the housing and base are joined by ensuring that the housing and base adhere to and are fixed together.

[0010] In light of the foregoing points, the first objective of the present invention is to ensure the degree of freedom in design. A second objective is to ensure the predetermined passage area while maintaining the flame-extinguishing function.

[0011] The above tasks are solved by an electromagnetic relay according to claim 1.

[0012] Accordingly, the position of the ventilation holes can be determined without being restricted by the position of a connection insertion hole. This improves the design freedom.

[0013] Because the size of the ventilation holes can be determined without being affected by the width of a connection, it is easier to ensure a flame-extinguishing function and a predetermined passage area.

[0014] Furthermore, the shell and the base can be joined by a process different from gluing (adhering), because it is unnecessary to ensure airtightness in the section where the shell and the base are joined.

[0015] Further advantageous embodiments are disclosed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a sectional view showing an electromagnetic relay according to a first embodiment of the present invention. Fig. 2 is a view of an arrow II of the Fig. 1 out. Fig. 3 is a sectional view along a line III-III of the Fig. 1 considered. Fig. 4 is an enlarged sectional view showing part IV of the Fig. 1 shows. Fig. 5 is an enlarged view showing part V of the Fig. 2 shows. Fig. Figure 6 is a view showing an electromagnetic relay according to a modification of the first embodiment of the present invention. Fig. Figure 7 is a perspective view showing an electromagnetic relay according to a second embodiment of the present invention. Fig. Figure 8 is a view showing an electromagnetic relay according to a modification of the second embodiment of the present invention. DESCRIPTION OF EXECUTION FORMS

[0016] Several embodiments for carrying out the present invention are described below with reference to the drawings. In the corresponding embodiments, a part corresponding to the subject matter described in a preceding embodiment may be assigned the same reference numeral, and a redundant explanation for that part may be omitted. If only one part of a configuration is described in one embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined, even if it is not expressly stated that the parts may be combined. The embodiments may be partially combined, even if it is not expressly stated that the embodiments may be combined, provided that the combination is harmless. (First embodiment)

[0017] An electromagnetic relay according to a present embodiment can be used for an electric vehicle on which a fuel cell is mounted. The fuel cell uses hydrogen gas, which is a flammable gas.

[0018] As in Fig. As shown in Figures 1 to 3, the electromagnetic relay of the present embodiment comprises a shell 10 made of a resin. The shell 10 includes four shell side walls 101 and a shell base 102. The shell 10 has a shell opening 103 on one side of the shell 10, opposite the shell base 102. The shell 10 has a rectangular cylindrical shape with a base. A housing chamber 104 is provided in the shell 10, and the housing chamber 104 is open to the outside of the shell 10 through the shell opening 103.

[0019] A resin-based base 12 comprises a base 121 connected to the shell 10 to close the shell opening 103, a base body 122 projecting from the base 121 towards the shell base 102, and a base spring support 123 supporting a compression spring 38 described below. The housing space 104 is bounded by the shell 10 and the base 121. The base 12 is formed by overmolding with a pair of fixed elements 14 as inserted components.

[0020] The base 121 includes two connection insertion holes 124 through which a pair of coil terminals 20 described below is inserted.

[0021] When the base 12 is attached to the sleeve 10, the base 12 is inserted into the sleeve 10 by moving the base 12 from right to left with respect to the sleeve 10 on the paper of the Fig. 1 is moved as indicated by an arrow X. Hereinafter, an insertion direction of the base 12 at the time of attachment of the base 12 to the shell 10 is referred to as a base insertion direction X. The shell 10 and the base 12 are connected to each other by a snap-fit ​​fastening feature (not shown).

[0022] The pair of fixed elements 14, made of conductive metal plates, is fixed to the base 12. One end of each fixed element 14 is fixed to the base body 122 and arranged within the housing space 104, with another end of the fixed element 14 projecting outwards. One end section of the fixed element 14 within the housing space 104 is fixed to a fixed contact 16, which is made of conductive metal by crimping. Another end section of the fixed element 14 in an external space is connected to an external electrical circuit (not shown). The fixed element 14 and the fixed contact 16 can be considered an example of a pair of fixed contact elements, one end of which is arranged within the housing space 104 and which are fixed to the base 12.

[0023] A coil 18, which has a circular cylindrical shape, is arranged in the housing space 104 and generates an electromagnetic force when current is applied to the coil 18. The coil 18 is connected to a pair of coil terminals 20, which are made of a conductive metal.

[0024] Each coil terminal 20 is inserted into the corresponding terminal insertion hole 124 such that one end of the coil terminal 20 extends outside the electromagnetic relay. Specifically, the coil terminal 20 is pressed into the terminal insertion hole 124. There is no play between the coil terminal 20 and the inner wall that defines the terminal insertion hole 124. The coil terminal 20 is connected to an ECU (not shown) via an external wiring harness. Current is supplied to the coil 18 through the external wiring harness and the coil terminal 20.

[0025] A plate 22, which has a circular plate shape and is made of a ferromagnetic metal, is arranged between the coil 18 and the base body 122. A yoke 24, also made of a ferromagnetic metal, is arranged on one side of the coil 18 that points away from the base body 122 and on the other side of the coil 18 that points radially outwards. The plate 22 and the yoke 24 are fixed to the base 12.

[0026] A fixed core 26, which has a circular cylindrical shape and is made of a ferromagnetic metal, is arranged in a radially inner space of the coil 18. The fixed core 26 is supported by the yoke 24.

[0027] A movable core 28, which has a circular plate shape and is made of a ferromagnetic metal, is arranged between the base body 122 and the plate 22. A return spring 40 is arranged between the coil 18 and the movable core 28 and pushes the movable core 28 away from the fixed core 26.

[0028] When the coil 18 is energized, the movable core 28 is attracted towards the fixed core 26 against a repulsive force of the return spring 30 by an electromagnetic force generated by the coil 18. The plate 22, the yoke 24, the fixed core 26, and the movable core 28 form a magnetic path for a magnetic flux induced by the coil 18.

[0029] A metal shaft 32 extends through the movable core 28 and is fixed to it. One end of the shaft 32 extends away from the fixed core 26 and is inserted into and fixed to an insulator 34, which is made of a resin with high insulating properties. The other end of the shaft 32 is slidably inserted into the fixed core 26.

[0030] A movable element 36, made of a conductive metal plate, is housed in the housing space 104. The compression spring 38 is arranged between the movable element 36 and the base spring support 123 and pushes the movable element 36 towards the insulator 34. The movable element 36 is provided with two movable contacts 40, made of a conductive material, which are crimped and fixed in positions corresponding to the two fixed contacts 16. The movable elements 36 and the movable contacts 40 can be considered an example of a movable contact element arranged in the housing space 104 and driven by the electromagnetic force generated by the coil 18 to make contact with or separate from the fixed contact elements.

[0031] A pair of permanent magnets 42 is arranged in a recess of the base body 122. The permanent magnets 42 generate magnetic fields in contact separation regions where the fixed contacts 16 and the movable contacts 40 touch or separate, thereby creating an arc that is generated between the fixed contacts 16 and the movable contacts 40. The permanent magnets 42 are arranged to face each other in a direction along which the pair of contact separation regions is oriented (that is, a right-left direction on the paper of the Fig. 3).

[0032] Several ventilation holes 50 are formed in a section where the casing 10 and the base 121 are connected. The housing chamber 104 is connected to an exterior of the electromagnetic relay through the ventilation holes 50.

[0033] The ventilation holes 50 are described below with reference to Fig. 4 and Fig. 5 described.

[0034] An inner wall surface of the shell side wall 101 has a shell receiving surface 105 that is perpendicular to the basic insertion direction X. The shell receiving surface 105 is formed on each of the four shell side walls 102.

[0035] The thickness of a portion of the shell sidewall 101 between the shell receiving surface 105 and the shell opening 103 is thinner than the thickness of a portion of the shell sidewall 101 between the shell receiving surface 105 and the shell bottom 102. Hereinafter, the thinner portion of the shell sidewall 101 between the shell receiving surface 105 and the shell opening 103 is referred to as a thin-walled shell section 101a.

[0036] Several shell projections 106 extend from an inner wall surface of the thin-walled shell section 101a towards the base 121 in a direction perpendicular to the base insertion direction X. The shell projections 106 are provided on each of the four thin-walled shell sections 101a.

[0037] Several base projections 125 are provided next to an outer circumferential edge of the base base 121 and protrude from a surface of the base base 121 that is opposite the housing space 104 in the direction of the shell receiving surface 105 in the base insertion direction X.

[0038] When the shell 10 and the base 12 are connected, the tips of the shell projections 106 are in contact with an outer circumferential surface of the base 121, that is, a surface of the base 121 that is opposite the shell thin-walled part 101a. Accordingly, first gaps 52 are formed between the shell thin-walled part 101a and the outer circumferential surface of the base 121.

[0039] When the shell 10 and the base 12 are connected, the tips of the base projections 125 are in contact with the shell receiving surface 105. Accordingly, a second column 54 is formed between the shell receiving surface 105 and the surface of the base bottom 121, which faces the housing space 104. The first column 52 and the second column 54 represent the ventilation holes 50.

[0040] The dimensions of the first column 52 and the dimensions of the second column 54 are set to a size that allows a flame passing through them to be extinguished. In particular, if a flammable gas flowing into the housing space 104 is hydrogen gas, the dimensions of the first column 52 and the dimensions of the second column 54 are set to 0.3 millimeters or less.

[0041] Next, the operation of the electromagnetic relay of the present embodiment will be described. First, when the coil 18 is energized, the movable core 28 is attracted towards the fixed core 26 by the electromagnetic force against the compressive force of the return spring 30. The movable element 36 is pushed by the compression spring 38 and follows the movable core 28. Correspondingly, the two movable contacts 40 make contact with the two fixed contacts 16, and a connection is established between the pair of fixed elements 14.

[0042] When the coil 18 is energized, the movable core 28 and the movable element 36 are forced against the compressive force of the compression spring 38 by the return spring. Accordingly, the two movable contacts 40 are separated from the two fixed contacts 16, and the connection between the pair of fixed elements 14 is interrupted.

[0043] In an environment where flammable gas is present around the electromagnetic relay, the flammable gas can flow into the housing chamber 104 through the ventilation holes 50. The flammable gas in the housing chamber 104 can be ignited by an arc generated between the fixed contacts 16 and the movable contacts 40.

[0044] When a flame, caused by the arc igniting the flammable gas, passes through the ventilation holes 50 (i.e., the first column 52 and the second column 54), heat is drawn from the flame by the casing 10 and the base 12. Therefore, the flame cannot be sustained and is extinguished. This prevents the flame, caused by the arc igniting the flammable gas, from escaping the electromagnetic relay and igniting the flammable gas present around the electromagnetic relay.

[0045] According to the present embodiment, the positions of the ventilation holes 50 can be determined without being limited by the positions of the connection insertion holes 124. This improves the design freedom.

[0046] Furthermore, the dimensions of the ventilation holes 50 can be determined without being affected by the width of the coil connection 20. Therefore, it is easier to ensure a flame-extinguishing function and a predetermined throughput area.

[0047] Furthermore, it is unnecessary to maintain an airtight seal in the section where the shell 10 and the base 12 are joined. Therefore, the shell 10 and the base 12 can be joined by a method other than gluing (adhering).

[0048] In the embodiment described above, the first columns 52 are formed by providing the shell projections 106 on the shell 10. Alternatively, as in a Fig. In the modification shown in Figure 6, second base projections 126 are provided on the outer circumferential surface of the base base 121, and wherein the pointed ends of the second base projection 126 can touch the thin-walled shell part 121a, thereby providing the first columns 52.

[0049] In the embodiment described above, the second columns 54 are provided by the base projections 125 on the base 12. Alternatively, second shell projections can be provided on the shell receiving surface 105, wherein the pointed ends of the second shell projections contact the surface of the base 121 that faces the housing space 104, thereby providing the second columns 54. (Unclaimed second embodiment)

[0050] A second embodiment is described with reference to Fig. 7. In the present embodiment, the positions of the ventilation holes 50 differ from those of the first embodiment. In the present embodiment, explanations of sections that are similar or equivalent to sections of the first embodiment are omitted or simplified.

[0051] As in Fig. As shown in Figure 7, in the present embodiment a ventilation hole 50 is provided on a single shell 10, through which a housing space 104 (see Figure 7) can be accessed. Fig. 1) is connected to an exterior. More precisely, the ventilation hole 50 is a rectangular longitudinal slot extending through a shell side wall 101. A dimension S of a short side of the ventilation hole 50 is set to a dimension that allows a flame passing through it to be extinguished.

[0052] When a flame caused by an electric arc igniting a flammable gas passes through the ventilation hole 50, heat is drawn from the flame by the casing 10 and the flame cannot be sustained and is extinguished.

[0053] According to the present embodiment, a position of the ventilation hole 50 can be determined without being affected by the position of a connection insertion hole 124 (see Fig. 2) to be limited. This improves the degree of design freedom.

[0054] Furthermore, the dimension of the ventilation hole 50 can be determined without being affected by a width dimension of a coil connection 20 (see Fig. 2) to be impaired. Therefore, it is easier to ensure a flame-extinguishing function and a predetermined passage area.

[0055] In the second, unclaimed embodiment described above, the ventilation hole 50 is provided on the casing 10. Alternatively, as in Fig. As shown in Figure 8, the ventilation holes 50 are provided on the base 121 without being connected to the connection insertion hole 124.

[0056] In the embodiments described above, the shell 10 is made of a resin, but the shell 10 can also be made of a metal. Similarly, in the embodiments described above, the base 12 is made of a resin, but the base 12 can also be made of a ceramic.

[0057] The present invention is not limited to the embodiments described above and can be modified as desired within the scope described in the claims.

Claims

[1] Electromagnetic relay, with: a shell (10) which has a housing space (104) which is open to an exterior of the shell (10) through an opening (103); a base (12) which is connected to the shell (10) to close the opening (103); a coil (18) which is arranged in the housing space (104) to generate an electromagnetic force when the coil (18) is energized; a pair of fixed contact elements (14, 16) which are fixed to the base (12) and one end of which is arranged in the housing space (104); a movable contact element (36, 40) arranged in the housing space (104) and driven by the electromagnetic force generated by the coil (18) to touch or separate from the fixed contact elements (14, 16); and a plurality of ventilation holes (50) through which the housing space (104) is connected to the outside, wherein the ventilation holes (50) are set to a size that makes it possible to extinguish a flame passing through the ventilation holes (50), wherein the multitude of ventilation holes (50) are arranged in a section where the shell (10) and the base (12) are connected, and one of the shell (10) and the base (12) has a plurality of projections (106, 126) having pointed ends that touch the other of the shell (10) and the base (12), such that the plurality of projections (106, 126) defines the plurality of ventilation holes (50) between the shell (10) and the base (12). [2] Electromagnetic relays according to claim 1, wherein the base (12) has a base base (121) fitted into a shell wall of the shell (10) that delimits the housing space (104) and a base body (122) extending from the base base (121) in a base insertion direction (X) into the housing space (104), the shell wall has a shell receiving surface (105) that is perpendicular to the base insertion direction (X) and faces the base floor (121), the shell wall has a thin-walled part (101a) and a thick-walled part, such that the thin-walled part (101a) is located in the base insertion direction (X) between the thick-walled part and the base bottom (121), an inner surface of the thin-walled part (101a) is recessed by an inner surface of the thick-walled part, such that the shell receiving surface (105) is between the thin-walled part (101a) and the thick-walled part, and the multitude of projections (125) are provided on one of the shell receiving surface (105) of the shell (10) and the base floor (121) and project in the base insertion direction (X). [3] Electromagnetic relay according to claim 2, wherein the plurality of projections (106, 126) are also provided on one / a of the inner surface of the thin-walled part (101a) and the base bottom (121) and project in a direction perpendicular to the base insertion direction (X).

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