Electromagnetic relay

An electromagnetic relay includes a contact including a movable spring having a base end fixed to a bottom of a housing and a tip end provided with a movable contact, and a fixed spring having a base end fixed to the bottom of the housing and a tip end provided with a fixed contact. The movable contact is provided opposite to the fixed contact so as to come in contact with the fixed contact or move away therefrom. The housing has a protrusion protruding toward a side of the fixed contact opposite to a side facing the movable contact.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Application No. 2011-217841, filed Sep. 30, 2011 and Japanese Application No. 2012-138509 filed Jun. 20, 2012, the entire contents of both are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an electromagnetic relay.

2. Description of the Related Art

An electromagnetic relay which includes an electromagnet, an actuator which is actuated in response to a magnetic action of the electromagnet, a contact which opens and closes in response to the actuation of the actuator, and a housing for accommodating the electromagnet, the actuator and the contact is known (See JP 2008-210776 A.).

There is a need for an electromagnetic relay with improved reliability of an opening and closing operation of a contact part.

SUMMARY OF THE INVENTION

According to one embodiment, an electromagnetic relay is provided, the electromagnetic relay comprising: an electromagnet; an actuator which is actuated in response to a magnetic action of the electromagnet; a contact which opens and closes in response to the actuation of the actuator; and a housing for accommodating the electromagnet, the actuator and the contact, wherein the contact includes a movable spring having a base end fixed to a bottom of the housing and a tip end provided with a movable contact, and a fixed spring having a base end fixed to the bottom of the housing and a tip end provided with a fixed contact, the movable contact being provided opposite to the fixed contact and being moved in response to the actuation of the actuator, coming in contact with the fixed contact or moving away from the fixed contact, and wherein the housing has a protrusion protruding toward a side of the fixed contact opposite to a side facing the movable spring.

DETAILED DESCRIPTION

Embodiments will be described below with reference to the drawings. Like elements commonly used in different embodiments or variants thereof are designated with the same reference numerals. For the purpose of clarifying the drawings, the size of one element in relation to another may be modified accordingly. Although a position of one element in relation to another or an orientation for fitting one element in relation to another may be specified in the following description, such particularities are not intended to limit the practical application or the configuration of the present invention, but merely based on the illustrated exemplary drawings, unless otherwise stated.

Referring toFIGS. 1 to 4, an electromagnetic relay10according to a first embodiment will be described.FIG. 1is an exploded perspective view illustrating the electromagnetic relay10,FIG. 2is a plan view illustrating the electromagnetic relay10,FIG. 3is a sectional view along an alternate short and long dash line inFIG. 2, taken in the direction III-III, andFIG. 4is a sectional view along the alternate short and long dash line inFIG. 2, taken in the direction IV-IV.

The electromagnetic relay includes an electromagnet part12, an actuator part14which is actuated in response to a magnetic action of the electromagnet part12, and a contact part16which opens and closes in response to the actuation of the actuator14. The electromagnetic relay10also includes a housing22which has a base18and a cover20, both of which are made of molding resin having an electrical insulation property. The base18has a bottom face24defining a bottom of the housing22and a base block26substantially having a tubular shape for electrically insulating the electromagnet part12from the contact part16. The cover20has a top wall20aand a peripheral wall20bextending downward in a vertical direction from a peripheral edge of the top wall20a. The top wall20aand the peripheral wall20bdefine a void space with an opening facing downward. The void space defined by the cover20has the sizes corresponding to those of the bottom face24of the base18in a longitudinal direction and a width direction. Thus, the cover20and the base18can be assembled into the housing22of the electromagnetic relay10which substantially defines a closed space in the interior thereof. Each component of the electromagnet part12, of the actuator part14and of the contact part16is accommodated in the interior of the housing22.

An injection hole27is formed in a side surface of the base block26in the vicinity of the bottom thereof. In an assembling process, which is not described in further details, adhesive can be applied into the base block26through the injection hole27to adhere a yoke34in position.

The electromagnet part12includes a spool28substantially having an H-shape in side view and made of molding resin with an electrical insulation property, a coil30formed by winding a conductive wire around a body portion28aof the spool28, a core32having a columnar shape extending along a central axis30aof the coil30and made of a magnetic material and, and a yoke34coupled to the core32to extend a magnetic path. The spool28has the body portion28ahaving a tubular hollow shape, and a pair of flanges28band28cextending from both ends of the body portion28asubstantially in the vertical direction. A through hole29is formed in the spool28as illustrated inFIGS. 3 and 4, extending through the body portion28aand the flanges28band28c. The spool28also has a pair of extended portions28dwhich extend in a longitudinal direction (a longer direction of the electromagnetic relay10), from both ends of the flange28bin a width direction (a shorter direction of the electromagnetic relay, i.e., an upward and downward direction inFIG. 2). A through hole (not shown) extending in the vertical direction is formed in each extended portion28d, and coil terminals36are fitted to the extended portion28dvia the through hole. Both ends of the conductive wire of the coil30are fixed to the pair of the coil terminals36. In this way, when a certain electric voltage is applied between the coil terminals36, electric power is supplied to the coil30, exciting the coil30to act as an electromagnet.

The core32has a flange32aextending along the flange28bof the spool28in the vertical direction, a body32bextending through the through hole29of the spool28, and a tip32chaving a small diameter than the body32b. The tip32cof the core32protrudes toward an inner surface of the base block26through the through hole29formed in the flange28c.

The yoke34made of a magnetic material is a plate substantially having an L-shape in side view and bent along a lower end of the flange28cof the spool28. The yoke34includes a vertical plate34aextending along an outer surface of the flange28cof the spool28in the vertical direction, and a lateral plate34bextending substantially in parallel to the central axis30aof the coil30from a lower end of the vertical plate34ato the vicinity of the flange32aof the core32. An attachment hole35is formed in the vertical plate34aof the yoke34in order to receive the tip32cof the core32. The yoke34and the core32are fixed together by means of caulking, for example, with the tip32cof the core32inserted through the attachment hole35of the yoke34.

The actuator part14includes an armature38which pivots in response to a magnetic action of the electromagnet part12, and a card40which moves in parallel to the central axis30aof the coil30in response to the pivoting movement of the armature38. The armature38is substantially a rectangular plate provided via a hinged spring42at a certain angle relative to the flange32aof the core32. The hinged spring42is at one end attached to the armature38and at the other end engaged with the yoke34. Specifically, the other end of the hinged spring42extends through a groove formed on the base18and is engaged with a cut-off portion44formed on the bottom surface of the lateral plate34bof the yoke34, as illustrated inFIGS. 3 and 4. In this manner, the hinged spring42is provided to bias the armature38in a direction away from the flange32aof the core32. Thus, when no electricity is supplied to the coil30as illustrated inFIGS. 3 and 4, the armature38is at a greater angle relative to the flange32aof the core32. Then, when a certain voltage is applied to the coil30through the coil terminals36, the armature38is attracted toward the flange32aof the core32against the biasing force by the hinged spring42, due to magnetic force generated by the electromagnet part12. In this way, the armature38pivots such that the angle relative to the flange32aof the core32decreases. When the electricity supplied to the coil30is cut again, the armature38returns to a position as illustrated with the aid of the biasing force of the hinged spring42. The pivoting movement of the armature38causes the contact part16to open and close.

The armature38has at its upper end a pair of protrusions46which protrude upward from both ends of the armature38in its width direction. The protrusions46are provided at an angle relative to each other, forming a gap therebetween which is greater at its tip than at its base. The card40is a rectangular frame made of resin, for example, with a pair of hooks48protruding outward from a first edge40ain its longitudinal direction. The hooks48of the card40are slanted inwardly such that its tips are closer to each other than its bases, allowing the hooks48to be engaged with the protrusions46. In cooperation of the protrusions46and the hooks48, the pivoting movement of the armature38is transmitted to the card40, allowing the card40to move in parallel to the longitudinal direction of the electromagnetic relay10. The card40also has a pair of acting portions50which protrude outwardly from a second edge40bof the card40opposite to the first edge40a. The acting portions50are brought into engagement with through holes64formed in a movable spring54, allowing a movable contact52of the movable spring54to move toward a fixed make contact56.

The contact part16includes a movable spring54carrying a movable contact52which moves in response to the movement of the card40, a fixed make spring58provided opposite to the movable spring54and carrying a fixed make contact56, and a fixed break spring62provided opposite to the movable spring54on the opposite side of the fixed make spring58and carrying a fixed break contact60. The movable spring54can be fixed by inserting its base end to a groove (not shown) formed in the base18. The movable contact52provided at a tip end of the movable spring54includes a first contact52aopposite to the fixed break contact60and a second contact52bopposite to the fixed make contact56. The movable spring54has a wider portion in the periphery of the movable contact52, and a pair of through holes64are formed in both sides of the wider portion of the movable contact52(FIG. 1). The movable spring54has at its base end a movable terminal54aextending downward to the outside through the base18(FIG. 4).

The fixed make spring58can be fixed by inserting its base end to a groove (not shown) formed in the base18. The fixed make spring58has at its base end a fixed make terminal58aextending downward to the outside through the base18(FIG. 3). The fixed break spring62can be fixed by inserting its base end to a groove (not shown) formed in the base18. The fixed break spring62has at its base end a fixed break terminal62aextending downward to the outside through the base18(FIG. 3). The movable terminal54a, the fixed make terminal58aand the fixed break terminal62aare spaced apart from one another such that they do not inadvertently come in contact with or interfere with one another.

When no electricity is supplied to the electromagnet part12, the movable contact52is in contact with the fixed break contact60as illustrated. In this state, the movable contact52is biased against the fixed break contact60by means of the movable spring54functioning as a spring. When electricity is supplied to the electromagnet part12, the actuator part14is actuated as described above, and the card40presses the movable spring54toward the fixed make spring58against biasing force of the movable spring54. As a result, the movable contact52moves away from the fixed break contact60, and come in contact with the fixed make contact56on the opposite side of the fixed break contact60. When the electricity is cut again, due to elasticity of the movable spring54, the contact part16returns to a state as illustrated, which is the state before the electricity is supplied. In this way, the electromagnetic relay10allows the contact part16to open and close.

Accordingly, this type of the electromagnetic relay10makes use of the movable spring54which functions as an elastically derormable spring, switching from a conducting state to conduct electricity to a blocking state to block electricity, or vice versa, between the movable contact52and the fixed break contact60and between the movable contact52and the fixed make contact56. Thus, the distance between the contacts may be designed within such a range that the switching operation of the contacts can be smoothly carried out with rated electric power. For example, if the fixed make spring58is subject to plastic deformation, forming a wider gap between the movable contact52and the fixed make contact56, it could be the case where it is not possible or barely possible for the movable contact52to come in contact with the fixed make contact56even when it is moved toward the fixed make contact56. Therefore, in this embodiment, the cover20has on its inner surface a protrusion66protruding toward the fixed make contact56. The protrusion66extends over an area such that the fixed make contact56comes in contact with the protrusion66, as the fixed make contact56is moved toward the inner surface of the cover20, as shown inFIGS. 3 and 4. The size of the protrusion66protruding toward the fixed make contact56is designed such that the fixed make contact56comes in contact with the protrusion66within a range that allows the fixed make spring58to be elastically deformed, in order to prevent the fixed make spring58from being plastically deformed.

The size of the protrusion66protruding toward the fixed make contact56may also be designed such that in a state where the movable contact52is in contact with the fixed make contact56(i.e., a state where the electromagnet part12has been excited), a side of the fixed make contact56opposite to the side facing the movable contact52comes in contact with the protrusion66. In this case, when the movable contact52is pressed against the fixed make contact56, no gap is formed between the fixed make contact56and the protrusion66. This configuration allows the protrusion66to absorb unexpected impact thereon caused by, e.g., the electromagnetic relay10falling down. Accordingly, the fixed make spring58can be prevented from being plastically deformed.

Next, an electromagnetic relay80according to a variant of the first embodiment will be described with reference toFIGS. 5 and 6.FIG. 5is a plan view illustrating the electromagnetic relay80, andFIG. 6is a partial sectional view along an alternate short and long dash line inFIG. 5, taken in the direction VI-VI. In the following description on various variants and embodiments, matters that have already been described in relation to the above embodiment will be omitted.

The electromagnetic relay80according to this variant includes a cover82having a top wall82a, a peripheral wall82bextending from a peripheral edge of the top wall82a, and a protrusion84formed on an inner surface of the peripheral wall82b. The protrusion84has a limiting portion84awhich protrudes toward the fixed make contact56to the extent that prevents the fixed make spring58from being plastically deformed. The protrusion84also has a slanted portion84bwhich extends from a lower end of the limiting portion84aand becomes gradually thinner toward a lower end thereof. The lower end of the slanted portion84bextends continuously to the peripheral wall82b. In this variant, the protrusion84has a slanted inner surface on the slanted portion84b. This configuration prevents the lower end of the protrusion84from coming in contact with the fixed make spring58by accident during a process of attaching the cover82to the base18. In other words, since the protrusion84has the slanted portion84bwhich is slanted such that the protrusion82becomes gradually thinner toward the lower end thereof in a direction in which the cover82is attached to the base18, a process of assembling the cover82and the base18together is smoothly carried out. In the illustrated variant, the slanted portion84bterminates near the middle of peripheral wall82bof the cover82. However, the slanted portion84bmay be lengthened or shortened by changing an angle of inclination, depending on the shapes of components such as the fixed make spring58or the shape of the base18.

FIG. 7is a bottom view illustrating the cover20or82of the electromagnetic relay10or80according to the first embodiment. The protrusion66or84in this embodiment has a flat surface86opposite to the fixed make contact56. Since it is inexpensive to produce such a protrusion66or84, the electromagnetic relay10or80can also be inexpensive.

FIG. 8is a bottom view illustrating the cover20or82of an electromagnetic relay according to another variant of the first embodiment. The protrusion66or84in this embodiment has a surface88opposite to the fixed make contact56and the surface88has an arc-shape protruding toward the fixed make contact56. With such an arc-shaped surface88, even when the fixed make spring58is twisted, for example, which makes difficult for the fixed make contact56to come in contact with the surface88of the protrusion66or84in a face-to-face manner, the fixed make spring58can be prevented from being plastically deformed. In other words, the arc-shaped surface88allows the fixed make contact56to come in contact with the protrusion66or84in any direction, enhancing reliability of an opening and closing operation of the contact part.

Referring toFIG. 9, an electromagnetic relay100according to a second embodiment will be described.FIG. 9is a sectional view illustrating the electromagnetic relay100, corresponding toFIG. 3. In this embodiment, the electromagnetic relay100includes a cover104having a top wall104aand a peripheral wall104bin the same manner as a conventional type. InFIG. 9, a base102illustrated with hatching has a base protrusion106extending upward from an edge102aat which the fixed make contact56is situated, along an inner surface of the peripheral wall104bof the cover104. The size of the base protrusion106protruding from the peripheral wall104btoward the fixed make contact56is designed such that the base protrusion106can achieve the same effect as the protrusion66or84in the first embodiment. Accordingly, the electromagnetic relay100in the present embodiment also prevents the fixed make spring58from being plastically deformed, maintaining reliability of an opening and closing operation of the contact part.

FIG. 10is a partial sectional view illustrating an electromagnetic relay according to a variant of the second embodiment, corresponding toFIG. 6. The electromagnetic relay110according to this variant includes a cover104having a top wall104aand a peripheral wall104bin the same manner as a conventional type. A base112illustrated with hatching inFIG. 10has a base protrusion114extending upward from a base edge112aat which the fixed make contact56is situated, along an inner surface of the peripheral wall104bof the cover104. The base protrusion114has a flat plate portion114aextending upward from the base edge112a, and a slanted portion114bhaving a slanted surface118such that the slanted portion114bbecomes gradually thinner from an upper end of the flat plate portion114atoward an end thereof. The slanted surface118of the slanted portion114bextends on a side of the base protrusion114opposite to a surface116facing the fixed make contact56. The slanted portion114bis slanted in such a way that forms a greater gap with the peripheral wall104btoward the end thereof. On the other hand, the surface116opposite to the fixed make contact56protrudes to the extent that prevents the fixed make spring58from being plastically deformed as described in relation to the first embodiment. Accordingly, the base protrusion114functions to prevent the fixed make spring58from being plastically deformed in the same manner as the other embodiments. Since the electromagnetic relay110in this variant includes the base protrusion114whose tip is slanted toward the interior, a possible accident is prevented, e.g., in the case where a lower end of the peripheral wall104bof the cover104is damaged when it comes in contact with an upper end of the base protrusion114during a process of assembling the cover104and the base112together. In other words, since the base protrusion114formed on the base112has a slanted surface in a manner that the base protrusion114becomes gradually thinner in a direction in which the cover104and the base112are assembled together, the assembling process can be smoothly carried out.

Referring toFIGS. 11 and 12, exemplary configurations of the surface of the base protrusion opposite to the fixed make contact56will be described.FIG. 11is a perspective view illustrating the base of the electromagnetic relay according to the second embodiment.FIG. 12is a perspective view illustrating the base of the electromagnetic relay according to a variant of the second embodiment.

The base120shown inFIG. 11includes a base protrusion122having a flat surface124opposite to the fixed make contact56. The base protrusion122having a rectangular shape in top view as illustrated facilitates a production process of the base protrusion122, and thus, the electromagnetic relay can also be inexpensive.

The base130shown inFIG. 12includes a base protrusion132having a surface134opposite to the fixed make contact56, and the surface134of the base protrusion132has an arc-shape protruding toward the fixed make contact56. With such an arc-shaped surface134, even when the fixed make spring58is twisted, for example, which makes difficult for the fixed make contact56to come in contact with the surface134in a face-to-face manner, the fixed make spring58can be prevented from being plastically deformed. In other words, the arc-shaped surface134allows the fixed make contact56to come in contact with the protrusion132in any direction, enhancing reliability of an opening and closing operation of the contact part.

FIG. 13is a partial sectional view illustrating an electromagnetic relay according to a third embodiment, corresponding toFIG. 6. As can been seen in comparison withFIG. 3or6, the electromagnetic relay according to this embodiment includes a cover140having a protrusion142protruding toward the fixed break contact60, instead of the protrusion66or84protruding toward the fixed make contact56. As shown inFIG. 13, the protrusion142hangs from an inner surface of a top wall140aof the cover140substantially in parallel to a peripheral wall140b. The protrusion142protrudes relative to the fixed break contact60to the extent that the fixed break spring62is prevented from being plastically deformed. Thus, the size of the protrusion142protruding relative to the fixed break contact60is designed such that the fixed break spring62comes in contact with the protrusion142within a range that allows the fixed break spring62to be elastically deformed.

The size of the protrusion142protruding relative to the fixed break contact60may also be designed such that in a state where the movable contact52is in contact with the fixed break contact60(i.e., a state where the electromagnet part12is not excited), a side of the fixed break contact56opposite to the side facing the movable contact52comes in contact with the protrusion142. In this case, when the movable contact52is pressed against the fixed break contact60by biasing force, no gap is formed between the fixed break contact60and the protrusion142. This configuration allows the protrusion142to absorb unexpected impact thereon caused by, e.g., the electromagnetic relay10falling down. Accordingly, the fixed break spring62can be prevented from being plastically deformed.

FIG. 14is a partial sectional view illustrating an electromagnetic relay according to a variant of the third embodiment, corresponding toFIG. 6. In this variant, the protrusion142protruding toward the fixed break contact60has a slanted portion144which is slanted in relation to a surface of the protrusion142opposite to the fixed break contact60. The slanted portion144is formed so as to become gradually thinner toward a tip end of the protrusion142. With the protrusion142having the slanted portion144formed thereon, the fixed break spring62can be prevented from being deformed by accident when the protrusion142comes in contact with the fixed break contact60during a process of assembling the cover140and the base18together. Therefore, the assembling process can be smoothly carried out. The shape of the slanted portion144as illustrated represents merely one example, and thus the protrusion142may also have the slanted portion144of different shapes.

FIG. 15is a bottom view illustrating a cover of the electromagnetic relay according to the third embodiment. The protrusion142in this embodiment has a flat surface142aopposite to the fixed break contact60. The protrusion142having such a shape facilitates a producing process of the protrusion142, and therefore the electromagnetic relay can also be inexpensive.

FIG. 16is a bottom view illustrating a cover of the electromagnetic relay according to another variant of the third embodiment. A protrusion142in this variant has a surface142opposite to the fixed break contact60and the surface142has an arc-shape protruding toward the fixed break contact60. With such an arc-shaped surface142a, even when the fixed break spring62is twisted, for example, which makes difficult for the fixed break contact60to come in contact with the surface142aof the protrusion142in a face-to-face manner, the fixed break contact60can still come in contact with the protrusion142. Therefore, the fixed break spring62can be prevented from being plastically deformed. In other words, the arc-shaped surface142aallows the fixed break contact60to come in contact with the protrusion142in any direction, enhancing reliability of an opening and closing operation of the contact part.

FIG. 17is a partial sectional view illustrating an electromagnetic relay according to a fourth embodiment, corresponding toFIG. 6. The electromagnetic relay in this embodiment includes a cover104having a top wall104aand a peripheral wall104bin the same manner as a conventional type. A base150illustrated with hatching inFIG. 17has a base protrusion152protruding from the base block26for electrically insulating the electromagnet part12and the contact part16, toward a side of the fixed break contact60opposite to the side facing the movable contact52. The size of the base protrusion152protruding relative to the fixed break contact60is designed such that the same effect as that described in relation to the third embodiment can be achieved. Therefore, the present embodiment can prevent the fixed break spring62from being plastically deformed, maintaining reliability of an opening and closing operation of the contact part.

FIG. 18is a plan view illustrating the base150of the electromagnetic relay according to the fourth embodiment with a part of the base150cut away. InFIG. 18, the base150is cut along dashed line A-A inFIG. 17. The base protrusion152has a slanted portion154which becomes gradually thinner in a direction defined along a shorter side of the electromagnetic relay. The slanted portion154is oriented in a direction in which the fixed break spring62is fitted in position to the base150. This configuration prevents the base protrusion152and the fixed break contact60from coming in contact with each other during a process of fitting the fixed break spring62to the base150, thereby preventing the fixed break spring62from being damaged. Therefore, the fitting process can be smoothly carried out.

Referring toFIGS. 19 and 20, examples of the configuration of a surface of the base protrusion152opposite to the fixed break contact60will be described.FIG. 19is a plan view illustrating a base of the electromagnetic relay according to a variant of the fourth embodiment with a part of the base cut away.FIG. 20is a plan view illustrating a base of the electromagnetic relay according to another variant of the fourth embodiment with a part of the base cut away. InFIGS. 19 and 20, the base150is cut along dashed line A-A inFIG. 17, similarly toFIG. 18.

As cane be seen fromFIG. 19, the base protrusion152formed on the base150has a flat surface156opposite to the fixed break contact60. The base protrusion152having such a shape facilitates a production process of the protrusion152, and therefore the electromagnetic relay can also be inexpensive.

The base150shown inFIG. 20has the base protrusion152having a surface158opposite to the fixed break contact60and the surface158has an arc-shape protruding toward the fixed break contact60. With such an arc-shaped surface158, even when the fixed break spring62is twisted, for example, which makes difficult for the fixed break contact60to come in contact with the surface158in a face-to-face manner, the fixed break spring62can be prevented from being plastically deformed. In other words, the arc-shaped surface158allows the fixed break contact60to come in contact with the protrusion152in any direction, enhancing reliability of an opening and closing operation of the contact part.

Although the particular embodiments have been described above, it is needless to say that the scope of the present invention will not be limited to those particularities. For example, the present invention can also be applied to a latch type of electromagnetic relay in which a permanent magnet is provided to the actuator part. In the illustrated embodiments, the protrusions for restricting movement of the fixed make spring or the fixed break spring are integrally formed to the base or cover of the electromagnetic relay. However, the protrusion may also be a separate part adhered to the base or cover.

In the embodiments, for the illustrative purpose, the protrusion is provided either on the side closer to the fixed make contact or on the side closer to the fixed break contact. However, it is also possible to provide both of the protrusions protruding toward the fixed make contact and toward the fixed break contact. This configuration prevents both the fixed make spring and the fixed break spring from being plastically deformed.