The present invention relates to an electromagnetic relay and, more particularly, to an electromagnetic relay having a twin contact structure.

Conventionally, there has been disclosed in, for example, a patent document 1 a two contact electromagnetic relay. The relay has a spring assembly 33 with a pair of divided portions extending in parallel and a pair of contact buttons 37 mounted on the divided spring portions. In this relay, the spring assembly 33 is moved by an actuator 22 which reciprocates in response to the changes of a direction of flow of electric current applied to a coil assembly 12, making and breaking the connections between the contact buttons 37 of the spring assembly 33 and the associated contact buttons 34 mounted on the terminal 31.

Patent Document 1: US Patent No. 7659800

In the electromagnetic relay, the contact buttons 37 are unlikely to make simultaneous contacts with the associated contact buttons 34 of the spring assembly 33, namely, a connection and disconnection between one contact button 37 and the associated one contact button 34 can occur earlier than that between the other contact button 37 and the associated the other contact button 34 due to variations in manufacturing and/or assembling thereof. The same problem occurs due to the repetition of the connection and disconnection over a long period of time. This may result in an unwanted adhesion of wearing particles generated at the previously connected and disconnected contact buttons to the subsequently connected and disconnected contact buttons, increasing contact resistance and the resultant heat generation of the subsequently connected and disconnected contact buttons. The document "EP 0 286 432 A2" discloses an electromagnetic relay according to the preamble of claim 1.

Considering the above described drawbacks, an object of the invention is to provide an electromagnetic relay capable of preventing the heat generation due to the wearing particles which can cause at the connection and disconnection of the contacts.

This object is achieved by the subject-matter of the independent claim 1. Further advantageous embodiments are the subject-matter of the dependent claims. Aspects of the invention are set out below.

According to the present invention, an electromagnetic relay for reciprocatingly moving an actuator plate by electrically energizing an electromagnetic unit is provided, causing a plurality of neighboring movable contacts to make and break contacts with a plurality of neighboring stationary contacts opposing the movable contacts, comprising a shield plate provided between one pair of the opposing movable and stationary contacts and the other pair of opposing movable and stationary contacts.

According to the invention, the shield plate prevents the wearing particles generated by the connection and disconnection of one pair of movable and stationary contacts from scattering and adhering to the other pair of movable and stationary contacts, which in turn prevents
an increase of contact resistance and a resultant heat generation.

In the invention, the electromagnetic relay comprises a movable contact plate which is divided at one end thereof into two pieces, wherein the movable contacts are mounted on the divided pieces. In particular, the shield plate is disposed in a first slit formed between the divided pieces. According to this aspect of the invention, the shield plate prevents the wearing particles from scattering and adhering to
the movable and stationary contacts, which in turn prevents an increase of contact resistance and a resultant heat generation.

In a preferred aspect of the invention, one of the movable contacts may be used as an opening/closing movable contact which makes contacts with one of the stationary contacts, and the other movable contact may be used as a conducting movable contact which makes contacts with the other stationary contact, the contacts of the opening/closing movable contact with the one stationary contact being made earlier than the contacts of the conducting movable contact with the other stationary contact.

According to this preferred aspect of the invention, the shield plate prevents the wearing particles generated by the connection and disconnection of the opening/closing movable contact from scattering and adhering to the conducting movable and stationary contacts, which in turn prevents an increase of contact resistance and a resultant heat generation of the conducting movable and stationary contacts.

In the invention, the electromagnetic relay comprises a stationary contact terminal supporting the opening/closing stationary contact and the conducting stationary contact, the stationary contact terminal having a second slit partitioning the opening/closing stationary contact and the conducting stationary contact.

According to this aspect of the invention, the shield plate can be positioned in a precise manner between the opening/closing and conducting stationary contacts, which reliably prevents the wearing particles from scattering and adhering to the contacts, which in turn prevents an increase of contact resistance and a resultant heat generation of the contacts.

In a preferred aspect of the invention, the shield plate may be inserted through an insertion hole of a housing accommodating the stationary contacts.

According to this preferred aspect of the invention, the shield plate can be mounted to the housing through the insertion hole, easing the assembling of the relay.

In another preferred aspect of the invention, the shield plate may be formed integrally with the actuator plate.

According to this aspect of the invention, the number of components and the assembling processes are reduced, which eventually increases the productivity of the relay.

In another preferred aspect of the invention, the shield plate may be formed of an insulating material.

According to this aspect of the invention, the insulating property increases significantly.

In the invention, at least one of surfaces of the shield plate opposing the opening/closing movable contact has convex and concave portions formed therein.

According to this aspect of the invention, an increase of the surface area of the shield plate allows the plate to catch a large amount of generated wearing particles, which considerably increases the insulating distance and the insulating property.

In the invention, the convex and concave portions are a plurality of parallel grooves.

According to this aspect of the invention, the generated wearing particles can be caught by the grooves, which prevents the wearing particles from scattering and adhering for a long time and increases the insulating property.

• Figs. 1A and 1B are a perspective view showing a first embodiment of an electromagnetic relay according to the present invention and a perspective view showing a state in which a cover is removed.
• Fig. 2 is an exploded perspective view showing the electromagnetic relay illustrated in Fig. 1A.
• Fig. 3 is an exploded perspective view showing the electromagnetic relay illustrated in Fig. 1A as seen at a different angle.
• Figs. 4A and 4B are exploded perspective views showing a movable contact terminal and a movable contact plate assembly illustrated in Fig. 2.
• Figs. 5A and 5B are perspective views showing only a contact mechanism illustrated in Fig. 1B as seen at a different angle.
• Fig. 6A is a front view showing the contact mechanism illustrated in Fig. 5, Fig. 6B is a partial sectional view taken along B - B lines of Fig. 6A, and Fig. 6C is a partial bottom view showing the portion in FIG. 6A.
• Fig. 7A is a perspective view showing an insulating shield plate and Fig. 7B is a view showing a variant of the insulating shield plate.
• Fig. 8A is a partial plan view showing a state in the middle of an operation and Fig. 8B is a schematic partial plan view showing the portion of Fig. 8A.
• Figs. 9A and 9B are a perspective view showing a second embodiment of an electromagnetic relay according to the present invention and a perspective view showing a state in which a cover is removed.
• Fig. 10 is an exploded perspective view showing the electromagnetic relay illustrated in Fig. 9A.
• Fig. 11 is an exploded perspective view showing the electromagnetic relay illustrated in Fig. 9A as seen at a different angle.
• Figs. 12A and 12B are exploded perspective views showing a movable contact terminal and a movable contact plate assembly illustrated in Fig. 10.
• Figs. 13A and 13B are perspective views showing only a contact mechanism illustrated in Fig. 9B as seen at a different angle.
• Fig. 14A is a front view showing the contact mechanism illustrated in Fig. 13, Fig. 14B is a partial sectional view taken along B - B lines of Fig. 14A, and Fig. 14C is a partial bottom view showing the portion in FIG. 14A.
• Fig. 15A is a perspective view showing an actuator plate including an insulating shield plate and Fig. 15B is a view showing a variant of the actuator plate.
• Fig. 16A is a partial plan view showing a state in the middle of an operation and Fig. 16B is a schematic partial plan view showing the portion of Fig. 16A.

With reference to Figs. 1A-16B, various embodiments of an electromagnetic relay according to the present invention will be described.

As shown in Figs. 1A to 8B, the electromagnetic relay according to the embodiment of the present invention generally includes a base 10, an electromagnetic unit 20, a stationary contact terminal 30, a movable contact terminal 40, a movable contact plate assembly 50 securely fixed to the movable contact terminal 40, a rotatable actuator 60, an actuator plate 70, a position regulating plate 80, and a cover 90.

The base 10, which is shaped in the form of rectangular box, has a partition wall 11 protruding from a bottom surface thereof and an engagement recess 11a formed on an upper portion of an inwardly-faced surface of the partition wall 11 as shown in Fig. 2. Also, the base 10 has a pair of terminal slits 12a and 12b formed on peripheral walls partially defining one of internal spaces partitioned by the partition wall 11. A press fitting groove 13 for press fitting one end of the movable contact terminal 40 which will be described below is formed in one of the internal spaces. The base 10 is provided with a positioning projection 14 and a positioning rib (not shown) for positioning the electromagnetic unit 20 which will be described below, in the other internal space separated from the one internal space by the partition wall 11. The positioning projection 14 and the positioning rib have positioning holes 14a provided on upper end surfaces thereof, respectively. In addition, the base 10 has mounting holes 16 provided at diagonally opposing corners thereof and has engaging projections 17 provided on respective outer peripheral surfaces of the base 10. The base has an insertion hole 18 defined in a peripheral side wall adjacent the peripheral side walls having terminal slits 12a and 12b defined therein, so that an insulating shield plate 85 described below can be inserted in the insertion hole 18 (Fig. 3).

As shown in Figs. 2 and 3, the electromagnetic unit 20 has a spool 21 with flanges 21a and 21b provided on opposite sides thereof, an iron core 23 inserted in a through-hole defined in the spool 21, a coil wound around the spool 21, and substantially L-shaped yokes 24 and 25 fixed to the opposite ends of the iron core 23 protruding from the spool 21. Three coil terminals 26a, 26b, and 26c are press fitted in an edge portion of the flange 21b. As shown in Fig. 2, the electromagnetic unit 20 is assembled in the base 10 as it is positioned by the partition wall 11, the positioning projection 14 and the positioning rib (not shown).

As shown in Fig. 2, the stationary contact terminal 30 has an opening/closing stationary contact 31 and a conducting stationary contact 32 fixed to one end thereof. The other end thereof is served as a terminal portion 33. The opening/closing stationary contact 31 is made of a metallic material with a high conductivity such as silver. The opening/closing stationary contact 31 and the conducting stationary contact 32 are configured so that a height of opening/closing stationary contact 31 from the stationary contact terminal 30 is greater than that of the conducting stationary contact 32. Also, the opening/closing stationary contact 31 has a greater diameter than the conducting stationary contact 32. A thickness of a silver material covering a surface of the opening/closing stationary contact 31 is greater than that of the conducting stationary contact 32. The stationary contact terminal 30 has a second slit 34 defined between the opening/closing and conducting stationary contacts 31 and 32.

One end of the movable contact plate assembly 50 is fixed to the movable contact terminal 40 through a fixing projection 41 provided on one end thereof (Fig. 6B). The other end thereof is served as a terminal portion 42. The movable contact terminal 40 has a third slit 43 defined in a line extending along a lower edge of the terminal portion 42.

As shown in Fig.4, the movable contact plate assembly 50 has stacked, first, second, third and fourth movable contact plates 51, 52, 53 and 54 of which one ends are fixed to the fixing projection 41 of the movable contact terminal 40. In the movable contact plate assembly 50, as shown in Fig. 3, an opening/closing movable contact 57 and a conducting movable contact 58 are fixed to the distal ends of first and second divided plate portions 55 and 56 divided to extend in parallel in its longitudinal direction, respectively, as shown in Fig. 4.

The opening/closing movable contact 57 is formed by a metallic material with a high conductivity such as silver. The opening/closing movable contact 57 and the conducting movable contact 58 are configured so that a height of opening/closing movable contact 57 from the movable contact plate assembly 50 is greater than that of the conducting movable contact 58. Also, the opening/closing movable contact 57 has a greater diameter than the conducting movable contact 58. A thickness of a silver material covering a surface of the opening/closing movable contact 57 is greater than that of the conducting movable contact 58. Furthermore, the first and second divided plate portions 55 and 56 have fold portions 55a and 56a formed at proximal portions thereof to have a substantially U-shaped configuration. The movable contact plate assembly 50 has a cutout 50b formed at a corner of the proximal end thereof.

Although the descriptions have been made to the embodiment in which the opening/closing stationary contact 31 and the opening/closing movable contact 57 have greater heights than the conducting stationary contact 32 and the conducting movable contact 58, respectively, the present invention is not restricted to the above embodiment. For example, at least one of the opening/closing stationary contact 31 and the opening/closing movable contact 57 may have a greater height than the conducting stationary contact 32 and the conducting movable contact 58.

The opening/closing stationary and movable contacts 31 and 57 have the same configuration. Also, the conducting stationary and movable contacts 32 and 58 have the same configuration.

Of course, the movable contact plate assembly 50 may be formed by at least two movable contact plates.

As shown in Fig. 4, the first movable contact plate 51 has two pieces 51a and 51b divided to extend in parallel in its longitudinal direction. The divided plates 51a and 51b have substantially U-shaped fold portions 51c formed at proximal portions thereof. Also, the first movable contact plate 51 has a plurality of fixing holes 51d arranged in parallel on the proximal end and a cutout 51e formed at the proximal end corner thereof. The divided plates 51a and 51b have a semicircular aperture 51f provided adjacent at distal ends thereof and around a portion in which the opening/closing movable contact 57 and the conducting movable contact 58 are provided. Aplate portion outside the aperture 51f is bent to form an elastically deformable bent portion 51g.

According to this embodiment, the substantially U-shaped aperture 51f is provided to surround the region in which the opening/closing movable contact 57 and the conducting movable contact 58 are disposed, and the plate portion outside of the aperture 51f is bent to form the elastically deformable bent portion 51g. This allows a contact pressure to be controlled by adjusting a shape and size of the aperture 51f and an angle of the bent portion 51g.

The aperture 51f is not limited to be semicircular, and it may be made of at least one straight line.

As shown in Fig. 4, the second movable contact plate 52 has two pieces 52a and 52b divided to extend in parallel in its longitudinal direction. The divided plates 52a and 52b have substantially U-shaped fold portions 52c formed at proximal portions thereof. Also, the second movable contact plate 52 has a plurality of fixing holes 52d arranged in parallel on the proximal end and a cutout 52e formed at the proximal end corner thereof.

As shown in Fig. 4, the third movable contact plate 53 has two pieces 53a and 53b divided to extend in parallel in its longitudinal direction. The divided plates 53a and 53b have substantially U-shaped fold portions 53c formed at proximal portions thereof. Also, the second movable contact plate 53 has a plurality of fixing holes 53d arranged in parallel on the proximal end and a cutout 53e formed at the proximal end corner thereof.

As shown in Figs. 6A and 6B, the second movable contact plate 54 has two pieces 54a and 54b extending in parallel in its longitudinal direction. The divided plates 54a and 54b have substantially U-shaped fold portions 54c formed at proximal portions thereof. Also, the second movable contact plate 54 has a plurality of fixing holes 54d arranged in parallel on the proximal end and a cutout 54e formed at the proximal end corner thereof. Press-fitting projections 54f are formed by stamping at the proximal end of the plate 54.

Upper and lower distal end portions of the divided plate 54a are bent in a direction to form a pair of upper and lower position regulating tongues 54g and 54g for engagement with an arm 72 of an actuator plate 70 described below.

Likerwise, a distal end of the divided plate 54b is bent in a direction to form a pair of upper and lower position regulating tongues 54h for engagement with the arm 72 of the actuator plate 70 described below. One of the position regulating tongue 54h is bent at opposite ends to form positioning ribs 54i for the positioning of the arm 72 in the widthwise direction of the tongue.

The movable contact terminal 40 with the movable contact plate assembly 50 fixed thereto is press fitted into the press fitting groove 13 of the base 10. In this operation, the lower end of the movable contact terminal 40 is inserted in the press fitting groove 13 of the base 10 from above. A thickness of the lower end of the movable contact terminal 40 including the fixing projection 41 is smaller than a width of the press fitting groove 13, ensuring a smooth assembling without causing any scraping debris. Also, because of the cutout 50b provided at one side corner of the movable contact plate assembly 50, a press fitting can be performed more easily.

A substantial resistive force is obtained at the insertion of the lower end of the movable contact terminal 40 into the press fitting groove 13 because a thickness of the movable contact terminal 40 including the press fitting projection 54f is greater than or equal to the width of the press fitting groove 13. A further pressing of the movable contact terminal 40 into the press fitting groove 13 causes the lower edge of the movable contact terminal to be forcedly engaged with the stepped portion (not shown) formed on the inside surface of the press fitting groove 13 and thereby held immovably.

Although the descriptions have been made to the embodiment in which the two press fitting projections 54f are formed on the fourth movable contact plate 54 of the movable contact plate assembly 50, the present invention is not limited thereto. For example, at least one press fitting projection 54f may be sufficient. Alternatively, two press fitting projections 54f may be provided on upper and lower ends of the fourth movable contact plate 54, namely, four fitting projections may be provided in total.

As shown in Figs. 2 and 3, the rotatable actuator 60 has first and second iron plates 61 and 62 integrally assembled therewith and holding a permanent magnet therebetween. The actuator 60 further has rotating shafts 63 and 64 protruding coaxially from the upper and lower surfaces and an operation arm 65 protruding from a side surface thereof.

The actuator 60 is mounted in the base 10 with the rotating shaft 63 inserted in the bearing recess (not shown) formed in the bottom surface of the base 10 so that one ends of the first and second iron plates 61 and 62 move to the magnetic poles 24a and 25a and the other ends of the first and second iron plates 61 and 62 move away from the magnetic poles 24a and 25a, and vice versa, alternately (Fig. 8).

As shown in Figs. 2 and 3, the actuator plate 70 has an engaging hole 71 formed on one end thereof. The rectangular engaging hole 71 is configured to engage with the operation arm 65 of the rotatable actuator 60. The actuator plate 70 further has an upwardly extending engaging arm 72 integrally formed therewith on the other end thereof to define an engaging slot 73 therebetween. The engaging arm 72 has two positioning projections 74 formed at lower side thereof.

The operation arm 65 of the rotatable actuator 60 is engaged in the engaging hole 71 of the actuator plate 70. The distal end of the movable contact plate assembly 50 is engaged in the engaging slot 73. The engaging arm 72 is engaged with the position regulating tongues 54g of the divided plate 54a of the fourth movable contact plate 54 and the position regulating tongues 54h of the divided plate 54b.

Further, the position regulating rib 54i of the position regulating tongue 54h are positioned between the pair of position regulating projections 74 of the engaging arm 72, preventing a displacement of the movable contact plate assembly 50 in a vertical or widthwise direction thereof, which ensures a reliable operating characteristic of the electromagnetic relay.

As shown in Figs. 2 and 3, the position regulating plate 80 has a planar configuration to extend between the positioning projection 14 and the positioning rib (not shown) . The plate 80 has positioning projections 81 and 82 provided at opposite ends of its lower surface, which are configured so that they can fit in the positioning holes 14a and 15a of the positioning projection 14 and the positioning rib (not shown), respectively. The plate 80 further has a through hole 83 provided on a central portion thereof so that the rotation shaft 64 of the rotatable actuator 60 can be engaged in the hole.

As shown in Fig. 3, the insulating shield plate 85 is configured so that it can be inserted from the insertion hole 18 of the base 10 and has a position regulating rib 86 formed integrally at one end thereof. As shown in Fig. 6B, the insulating shield plate 85 is inserted into the insertion hole 18 of the base 10 so that it extends through the second slit 34 of the stationary contact terminal 30 and the first slit 50a of the movable contact plate assembly 50 to reach the third slit 43 of the movable contact terminal 40. Consequently, the insulating shield plate 85 is positioned in the second slit 34, the first slit 50a and the third slit 43 to partition between the opening/closing stationary and movable contacts 31, 57 and the conducting stationary and movable contacts 32, 58.

As shown in Fig. 7B, the insulating shield plate 85 has a plurality of grooves 87 formed in parallel on a surface opposing at least the opening/closing stationary contact 31 and the opening/closing movable contact 57, increasing its surface area and its insulating property.

As shown in Figs. 2 and 3, a cover 90 takes a planar configuration such that it covers the opening of the base 10 and has at respective diagonally opposing corners thereof cylindrical connecting portions 91 formed with through-holes 91a. The cover 90 has elastic engaging portion 92s formed in respective positions of the outer peripheral edges, corresponding to the engaging projections 17 of the base 10. The cover 90 has a projection 93 formed on a ceiling thereof which engages with the corresponding engagement recess 11a of the partition wall 11 of the base 10.

The cover 90 is mounted from above on the base 10 supporting the above described components already mounted thereon. The cylinder portions 91 of the cover 90 are engaged in the holes 16 on the base 10, and the elastic engaging portions 92 of the cover 90 are engaged with the engaging projection 17 of the base 10, which completes the assembling of the base and the cover.

According to the embodiment, the larger diameter opening/closing movable contact 57 is disposed adjacent the opening of the base 10, which advantageously ensures a reliable inspection and adjustment at the assembling and an enhanced productivity of the relay.

Figs. 8A and 8B show the electromagnetic relay in operation. The descriptions about its operation will start from the condition in which one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are magnetically attracted to the magnetic poles 24a and 25a of the yokes 24 and 25 by a magnetic force of the permanent magnet, respectively.

From this condition, when the one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are attracted to the magnetic poles 24a and 25a of the yokes 24 and 25 respectively, the actuator plate 70 engaging with the operation arm 65 of the rotatable actuator 60 takes a return position. Then, the opening/closing and conducting movable contacts 57 and 58 are disconnected from the opening/closing and conducting stationary contacts 31 and 32. At this time, an opposing distance between the opening/closing stationary contact 31 and the opening/closing movable contact 57 is shorter than an opposed distance between the conducting stationary contact 32 and the conducting movable contact 58.

When a voltage is applied to the coil 22 in a manner such that it energizes to cancel the magnetic force of the permanent magnet, the rotatable actuator 60 rotates against the magnetic force of the permanent magnet, causing that one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are disconnected from the magnetic poles 24a and 25a of the yokes 24 and 25 and the other end 61b of the first movable iron plate 61 and one end 62a of the second movable iron plate 62 attract the magnetic poles 25a and 24a of the yokes 25 and 24, respectively. As a result, the operation arm 65 of the rotated rotatable actuator 60 slidingly moves the actuator plate 70 so that the inside surface of the engaging slot 73 of the actuator plate 70 simultaneously forces the bent portions 51g of the first movable contact plate 51. This in turn causes that the opening/closing movable contact 57 and the conducting movable contact 58 move around fixing projections 41 where the movable contact plates are fixed to the movable contact terminal 40. This results in that the opening/closing movable contact 57 makes a contact with the opening/closing stationary contact 31 (Fig. 6B) and then the conducting movable contact 58 comes in contact with the conducting stationary contact 32. Further, the actuator plate 70 forces the bent portions 51g of the movable contact plate assembly 50. It should be noted that, the bent portion 51g of the divided plate 51b with the conducting movable contact 58 is shorter than and has a greater spring constant than the bent portion 51g of the dividedplate 51a. This ensures that, even a small amount of movement of the conducting movable contact 58 relative to the opening/closing movable contact 57 eventually allows the opening/closing movable contact 57 and the conducting movable contact 58 to contact the opening/closing stationary contact 31 and the conducting stationary contact 32 with a uniform contact pressure, respectively.

The application of the voltage to the coil 22 is halted subsequently, in which the rotatable actuator 60 is held in the same position by the magnetic force of the permanent magnet.

Subsequently, when a voltage is applied to the coil 22 in a manner such that it energizes to cancel the magnetic force of the permanent magnet, the rotatable actuator 60 rotates in the opposite direction, causing the operation arm 65 to move the actuator plate 70 and also the engaging arm 72 of the actuator plate 70 to move the distal end of the movable contact plate assembly 50 back into their original positions, respectively.

According to the present embodiment, the relay is unlikely to be damaged by arcing which may occur between the opening/closing movable contact 57 and the opening/closing stationary contact 31. Also, the arcing is less-likely to occur between the conducting movable contact 58 and the conducting stationary contact 32. Advantageously, this prevents shortening of the contact life which would otherwise be caused by the contact wear and ensures a reliable conducting characteristic in the relay.

The insulating shield plate 85 partitions the opening/closing movable and stationary contacts 57, 31 and the conducting stationary and movable contact 32, 58. Then, even if the arcing occurs between the opening/closing movable contact 57 and the opening/closing stationary contact 31, the arcing particles do not adhere to the conducting stationary contact 32 or the conducting movable contact 58 which would otherwise cause an increase of the contact resistance and heating thereof.

Furthermore, the distal end portion of the insulating shield plate 85 is inserted to reach the third slit 43 of the movable contact terminal 40 and the insulating shield plate 85 is supported at opposite ends, which results in various advantages that the positioning precision increases and it is unlikely to drop off.

The electromagnetic relay according to the second embodiment is substantially the same as the first embodiment, as shown in Figs. 9A to 16B, except that the insulating shield plate 85 is integrally formed with the actuator plate 70, which reduces the number of components and/or the manufacturing processes and thereby increases the productivity of the relay. It should be noted that, since the insulating shield plate 85 is integrally formed with the actuator plate 70, no insertion hole needs to be made in the base 10.

As shown in Fig. 15A, the actuator plate 70 has a pair of engaging arms 75 and 76 formed at one end thereof so that they protrude laterally in parallel to form engaging slots 73 therebetween. The engaging slots 73 are configured so that the first and second divided plate portions 55 and 56 of the movable contact plate assembly 50 can engage.

As shown in Fig. 15B, the insulating shield plate 85 has a plurality of parallel grooves 87 formed on at least one of its front and rear surfaces of the insertion portion, opposing the opening/closing stationary contact 31, to increase a surface area and then the insulating property thereof.

In the second embodiment, as shown in Figs. 10 and 11, the stationary contact terminal 30, movable contact terminal 40 and movable contact plate assembly 50 have a second slit 34, third slit 43 and first slit 50a, respectively, for insertion of the insulating shield plate 85 in the same manner as in the first embodiment. The movable contact terminal 40 has a through hole 44 for insertion of the actuator plate 70 which will be described below, increasing a greater mechanical strength of the movable contact terminal 40 than the first embodiment.

The movable contact plate assembly 50 is substantially the same as that in the first embodiment as shown in Fig. 12, except that the distal end of one divided plate 54a has at its distal end a pair of position regulating tongues 54g by bending it in the same direction so as to engage upper and lower portions of the engaging arm 75 and the distal end of the other divided plate 54b has at its distal end a pair of position regulating tongues 54h by bending it in the same direction so as to engage upper and lower portions of the engaging arm 75.

Because other structures are substantially the same as the corresponding structures of the first embodiment, like parts are designated by like reference numerals and duplicate descriptions are eliminated.

Figs. 16A and 16B show the electromagnetic relay in operation. The descriptions about its operation will start from the condition in which one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are magnetically attracted to the magnetic poles 24a and 25a of the yokes 24 and 25 by a magnetic force of the permanent magnet, respectively.

From this condition, when the one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are attracted to the magnetic poles 24a and 25a of the yokes 24 and 25 respectively, the actuator plate 70 engaging with the operation arm 65 of the rotatable actuator 60 takes a return position. Then, the opening/closing and conducting movable contacts 57 and 58 are disconnected from the opening/closing and conducting stationary contacts 31 and 32. At this time, an opposing distance between the opening/closing stationary contact 31 and the opening/closing movable contact 57 is shorter than an opposed distance between the conducting stationary contact 32 and the conducting movable contact 58.

When a voltage is applied to the coil 22 in a manner such that it energizes to cancel the magnetic force of the permanent magnet, the rotatable actuator 60 rotates against the magnetic force of the permanent magnet, causing that one end 61a of the first movable iron plate 61 and the other end 62b of the second movable iron plate 62 are disconnected from the magnetic poles 24a and 25a of the yokes 24 and 25 and the other end 61b of the first movable iron plate 61 and one end 62a of the second movable iron plate 62 attract the magnetic poles 25a and 24a of the yokes 25 and 24, respectively. As a result, the operation arm 65 of the rotated rotatable actuator 60 slidingly moves the actuator plate 70 so that the inside surface of the engaging slot 73 of the actuator plate 70 simultaneously forces the bent portions 51g of the first movable contact plate 51. This in turn causes that the opening/closing movable contact 57 and the conducting movable contact 58 move around fixing projections 41 where the movable contact plates are fixed to the movable contact terminal 40. This results in that the opening/closing movable contact 57 makes a contact with the opening/closing stationary contact 31 (Fig. 16B) and then the conducting movable contact 58 comes in contact with the conducting stationary contact 32. Further, the actuator plate 70 forces the bent portions 51g of the movable contact plate assembly 50. This causes that the opening/closing movable contact 57 and the conducting movable contact 58 make contacts with the opening/closing stationary contact 31 and the conducting stationary contact 32, respectively.

The application of the voltage to the coil 22 is halted subsequently, in which the rotatable actuator 60 is held in the same position by the magnetic force of the permanent magnet.

Subsequently, when a voltage is applied to the coil 22 in a manner such that it energizes to cancel the magnetic force of the permanent magnet, the rotatable actuator 60 rotates in the opposite direction, causing the operation arm 65 to move the actuator plate 70 and also the engaging arm 72 of the actuator plate 70 to move the distal end of the movable contact plate assembly 50 back into their original positions, respectively.

According to the present embodiment, the relay is unlikely to be damaged by arcing which may occur between the opening/closing movable contact 57 and the opening/closing stationary contact 31. Also, the arcing is less-likely to occur between the conducting movable contact 58 and the conducting stationary contact 32. Advantageously, this prevents shortening of the contact life which would otherwise be caused by the contact wear and ensures a reliable conducting characteristic in the relay.

The insulating shield plate 85 partitions the opening/closing movable and stationary contacts 57, 31 and the conducting stationary and movable contacts 32, 58. Then, even if the arcing occurs between the opening/closing movable contact 57 and the opening/closing stationary contact 31, the arcing particles do not adhere to the conducting stationary contact 32 or the conducting movable contact 58 which would otherwise cause an increase of the contact resistance and heating thereof.

The electromagnetic relay according to the invention is not limited to that described above, and the invention can be applied to various electromagnetic relays and electronic devices.

10

base

11

partition wall

12a,

12b terminal slit

13

fitting groove

18

insertion hole

20

electromagnetic unit

21

spool

22

coil

23

iron core

24

yoke

24a

magnetic pole

25

yoke

25a

magnetic pole

30

stationary contact terminal

31

opening/closing stationary contact

32

conducting stationary contact

33

terminal portion

34

second slit

40

movable contact terminal

41

fixing projection

42

terminal portion

43

third slit

50

movable contact plate assembly

50a

first slit

50b

cutout

51

first movable contact plate

51f

aperture

51g

bent portion

52

second movable contact plate

53

third movable contact plate

54

fourth movable contact plate

54f

press fitting projection

54g

position regulating tongue

54h

position regulating tongue

55

first divided plate portion

56a

fold

57

opening/closing movable contact

58

conducting movable contact

60

rotatable actuator

61

first movable iron plate

62

second movable iron plate

63

rotating shaft

64

rotating shaft

65

operation arm

70

actuator plate

71

engaging hole

72

engaging arm

73

engaging slot

74

positioning projection

75

engaging arm

76

engaging arm

80

position regulating plate

85

insulating shield plate

86

position regulating rib

87

groove

90

cover