Abstract:
An electromagnetic relay includes a spool, a coil wound on the spool, an armature inserted in the through hole of the spool, a yoke fixed to the spool by fitting, hinge springs, a movable spring, a hinge spring fixing portion, an attaching/fixing portion, and at least one terminal. The armature operates upon excitation of the coil. The yoke has first and second opposing upright portions. One end of the armature is in contact with an end face of the first upright portion, and the other end thereof opposes the end face of the second upright portion. The hinge springs set the armature at a predetermined angle with respect to the yoke, and urge one end of the armature against the end face of the first upright portion to ensure magnetic connection. The movable spring has a movable contact and extends from one side of the hinge springs. The movable spring is connected to the armature. The hinge spring fixing portion extends from the ends side of the hinge springs that are not connected to the movable spring, to support them and the movable spring. The attaching/fixing portion attaches and fixes the hinge spring fixing portion on the first upright portion by a single operation. The terminal member is fixed to one end portion of the spool by press fitting and has a stationary contact adjacent to the movable contact.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an electromagnetic relay and, more particularly, to an inexpensive, small-height electromagnetic relay having a high breakdown voltage. 
     Conventionally, an electromagnetic relay is known in which the contacts are switched by driving an armature inserted in the hollow portion of a coil bobbin. Japanese Utility Model Laid-Open No. 5-94936 discloses a technique as the first prior art technique. According to this technique, a substantially flat plate-like armature is inserted in the hollow portion of a bobbin. A movable spring and the armature are connected to each other with a resin card so that the movable spring and the armature or a yoke will not come into contact with each other. The movable spring and the yoke are insulated from each other with a barrier integrally formed with a base. As a result, an electromagnetic relay having a high breakdown voltage between the contact and coil can be obtained. 
     The second prior art technique will be described with reference to FIG. 9. According to this prior art technique, a core 1003 is inserted in the cylindrical hollow portion of a spool 1001, and a coil 1002 is wound on the spool 1001 about the core 1003 as the center. One end of an L-shaped yoke 1004 is caulked at the lower end of the core 1003. One end of an armature 1011 supported by hinge springs 1009 caulked on the rear surface of the L-shaped yoke 1004 is in contact with the upper end of the upright portion of the L-shaped yoke 1004. The other end of the armature 1011 opposes the upper end of the core 1003. 
     The armature 1011 is connected to the hinge springs 1009 through a boss 1010. The other end of each hinge spring 1009 opposite to its hinge portion forms a movable spring 1008. A movable contact 1007 is formed on the distal end portion of the movable spring 1008. Stationary contacts 1006 are arranged to constitute a pair through the movable contact 1007. The opening portion of the case is sealed with an epoxy-based adhesive. 
     The conventional electromagnetic relay described above has problems as follows. The first problem is the high manufacturing cost. This is because the number of components is large. 
     The second problem is that the electromagnetic relay does not have a high breakdown voltage. This is because the excitation coil side (primary) and the contact side (secondary) are connected to each other through the space around the card. 
     The third problem is that the electromagnetic relay cannot be made compact. This is because the yoke needs a space for caulking the hinge spring stationary portion. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compact electromagnetic relay having a low manufacturing cost and a high breakdown voltage. 
     In order to achieve the above object, according to the present invention, there is provided an electromagnetic relay comprising a spool having a through hole, a cylindrical excitation coil wound on the spool, an armature inserted in the through hole of the spool to operate upon excitation of the excitation coil, a substantially U-shaped yoke fixed to two end portions of the spool by fitting, the yoke having first and second opposing upright portions, and one end of the armature being in contact with an end face of the first upright portion of the yoke and the other end of the armature opposing the end face of the second upright portion of the yoke, L-shaped hinge springs for setting the armature at a predetermined angle with respect to the yoke and urging the one end of the armature against the end face of the first upright portion of the yoke to ensure magnetic connection, a movable spring having a movable contact at a distal end thereof and extending from one end of the hinge springs to be connected to the armature, a hinge spring fixing portion extending from the ends of the hinge springs that are not connected to the movable spring, to support the hinge springs and the movable spring, an attaching mechanism for attaching and fixing the hinge spring fixing portion on an outer side surface of the first upright portion of the yoke by a single operation, and at least one terminal member fixed to one end portion of the spool by press fitting, the terminal member having a stationary contact adjacent to the movable contact of the movable spring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the main body of an electromagnetic relay according to the first embodiment of the present invention; 
     FIG. 2 is an exploded perspective view showing the main body of the electromagnetic relay shown in FIG. 1; 
     FIG. 3 is a perspective view showing the main body of an electromagnetic relay according to the second embodiment of the present invention; 
     FIG. 4 is an exploded perspective view showing the main part of the main body of an electromagnetic relay according to the third embodiment of the present invention; 
     FIG. 5 is an exploded perspective view showing the main part of the main body of an electromagnetic relay according to the fourth embodiment of the present invention; 
     FIG. 6 is an exploded perspective view showing the main part of the main body of an electromagnetic relay according to the fifth embodiment of the present invention; 
     FIG. 7 is an exploded perspective view showing the main part of the main body of an electromagnetic relay according to the sixth embodiment of the present invention; 
     FIG. 8 is a perspective view showing the main part of the main body of an electromagnetic relay according to the seventh embodiment of the present invention; and 
     FIG. 9 is a perspective view showing the main body of a conventional electromagnetic relay. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail with reference to the accompanying drawings. 
     FIGS. 1 and 2 show an electromagnetic relay according to the first embodiment of the present invention. Referring to FIGS. 1 and 2, round rod-shaped coil terminal members 2 made of an Ni--Cu alloy are fixed on a spool 1a having an I-shaped side surface by press fitting from below the spool 1a. The spool 1a is made of a thermoplastic resin and has flange portions on its two ends. Holding and rotation preventive squeezed portions 22 are formed on the coil terminal members 2 in advance. One end of a winding is tied up on an IN-side coil tie-up portion 3a and wound on the spool 1a by a predetermined number of times to form a coil 3c. The other end of the winding is tied up on an OUT-side coil tie-up portion 3b, and the two ends of the winding of the coil 3c are fixed with solder, thereby completing a coil bobbin. 
     A yoke 4a with a substantially U-shaped side surface and made of pure iron, which has a pair of opposing upright portions 40a and 40b, is fixed on the two ends of the spool 1a having the I-shaped side surface by fitting. The first and second upright portions 40a and 40b of the yoke 4a oppose an inner hole 70 of the spool 1a. The insulating distance between the coil 3c and the yoke 4a is set by adjusting the length of the first and second upright portions 40a and 40b. Subsequently, terminals 5a and 5b each having a substantially L-shaped side surface and formed of a lead frame member are fixed on one end portion of the spool 1a by press fitting. Stationary contacts 6 made of a silver-oxide complex alloy are formed on the terminals 5a and 5b, respectively, by caulking. When fixing the yoke 4a and the terminals 5a and 5b with each other, they are fitted with the press-fit portions of the spool 1a with an interference fit of several ten μm. The press-fit stroke is determined by abutment with the respective components and the press-fit portions of the spool 1a. The stationary contacts 6 of the terminals 5a and 5b are located at positions to oppose a movable contact 7. 
     A movable spring 8, a pair of hinge springs 9, and a hinge spring fixing portion 10 are made integrally of a coil material for springs, and the movable contact 7 is caulked at the distal end portion of the movable spring 8. The hinge springs 9 are formed to each have an L-shaped side surface, and the rectangular movable spring 8 and the hinge spring fixing portion 10 extend from the two ends of the hinge springs 9. The movable spring 8 is arranged on an armature 12a, and a circular hole 88 of the movable spring 8 is fitted on a projection 12b formed on the upper surface of the armature 12a, so that the movable spring 8 is connected to the armature 12a. At this time, the movable spring 8 should not float from or be pressed on the armature 12a. 
     The armature 12a connected to the movable spring 8 is inserted in the inner hole 70 of the spool 1a and is set in position by aligning the outer side surface of the upright portion 40a of the yoke 4a and one end of the armature 12a with a pawl portion 12c. Simultaneously, the movable contact 7 of the movable spring 8 opposing from the inner hole 70 of the spool 1a is arranged between the stationary contacts 6 of the terminals 5a and 5b. At this time, the hinge spring fixing portion 10 is not in contact with the outer side surface of the upright portion 40a of the yoke 4a due to the bending angle of the hinge springs 9 that apply a breaking contact pressure to the movable contact 7. 
     The hinge spring fixing portion 10 is brought into contact with the outer side surface of the upright portion 40a of the yoke 4a while pulling its common terminal 11 in the direction of its distal end such that a pair of opposing rod-shaped projecting pieces 113 formed on the end face of the spool 1a do not come into contact with the upper portions of the two sides of the hinge spring fixing portion 10. As a result, an elliptic hole 100 formed at the center of the hinge spring fixing portion 10 engages with a circular projecting portion 44 formed on the outer side surface of the upright portion 40a of the yoke 4a. The pair of rod-shaped projecting pieces 113, the elliptic hole 100 of the hinge spring fixing portion 10, and the circular projecting portion 44 of the upright portion 40a of the yoke 4a constitute an attaching/fixing portion 200 of the hinge spring fixing portion 10 for the yoke 4a. 
     This will be described in detail. The elliptic hole 100 of the hinge spring fixing portion 10 is engaged with the circular projecting portion 44 of the upright portion 40a of the yoke 4a while-biasing the common terminal 11 downward, such that the hinge springs 9 extend between the pair of opposing rod-shaped projecting pieces 113 and that the hinge spring fixing portion 10 extends below the rod-shaped projecting pieces 113. When the elliptic hole 100 is engaged with the circular projecting portion 44 and is held by it, the rotation moment and the vertically upward pulling force of several 100 gw are applied to the common terminal 11 by the hinge springs 9. 
     In this embodiment, a gap corresponding to the thickness of the hinge spring fixing portion 10 is set between the outer side surface of the upright portion 40a of the yoke 4a and the rod-shaped projecting pieces 113. When the common terminal 11 which is held is released vertically upward against the rotation moment described above, the two end portions of the hinge spring fixing portion 10 are automatically inserted in the gap between the outer side surface of the upright portion 40a of the yoke 4a and the rod-shaped projecting pieces 113. As a result, the hinge spring fixing portion 10 is fixed such that it will not be disengaged even if it receives the rotation moment from the hinge springs 9. Due to engagement of the circular projecting portion 44 and elliptic hole 100, the hinge spring fixing portion 10 will not be pulled vertically upward stronger than necessary, and a pressure applied from the armature 12a to the yoke 4a, which is necessary to obtain desired characteristics, is ensured. After this, a known case made of a transparent resin and having an opening portion is placed on the main body of the electromagnetic relay, and the opening portion is sealed. 
     As described above, in the main body of the electromagnetic relay according to the present invention, when compared to the conventional examples, a card that interlocks the contact springs and the armature can be eliminated, and the main body can be assembled very easily. Because of the unique hinge spring fixing method, the step of caulking the hinge spring fixing portion and the yoke is not required, unlike in the conventional case, and extra spaces for caulking need not be reserved in both the hinge spring fixing portion and the yoke, thus achieving downsizing. 
     A method of assembling the main body of the electromagnetic relay having the above arrangement will be described in detail. 
     Nickel silver coil terminals each having a diameter of 0.56 mm are press-fitted in the spool 1a made of polybutylene terephthalate (30%-glass reinforced). Each rotation preventive squeezed portion 22 has a length of 1 mm and a width of 0.65 mm with respect to the press-fit holes (with a diameter of 0.6 mm) of the spool 1a. The coil 3c made of a polyurethane copper wire is tied up on the IN-side coil tie-up portion 3a, is wound on the spool 1a, and is then tied up on the OUT-side coil tie-up portion 3b. Thereafter, the two tie-up portions 3a and 3b are soldered. The two tie-up portions 3a and 3b have a length of 1.5 mm. 
     An electromagnetic soft-iron plate (thickness: 1 mm) is bent to form the yoke 4a having the pair of upright portions 40a and 40b. The upper half of the upright portion 40b is further bent 90° to form a magnetic pole surface 400. In this embodiment, the outer curved side surface of this 90°-bent portion 400a is further formed to have corners in order to increase the area of the magnetic pole surface 400. Subsequently, positioning is performed with respect to the yoke 4a by using the inner side surfaces of the pair of upright portions 40a and 40b as the press-fit surfaces and the two upper end faces of the portions 40a and 40b as the abutting surfaces. The circular projecting portion 44 of the upright portion 40a is formed by embossing to have a diameter of 1 mm and a height of 0.8 mm. 
     The stationary contact 6 is formed on one side of each of the pair of terminals 5a and 5b made of a 0.4-mm thick high-conductivity lead frame member, and the other side of each of the terminals 5a and 5b is cut and raised in a cantilevered manner to form a tongue piece 555a or 555b having a width of 1 mm and a length of 1 to 2 mm. Projecting portions 55a and 55b are formed on the tongue pieces 555a and 555b at the forward portions in the press-fit direction on the same surfaces, respectively. When fixing the terminals 5a and 5b in the spool 1a by press fitting, the projecting portions 55a and 55b serve as the guides. As the terminals 5a and 5b are inserted, they are fixed in the spool 1a by, press fitting, with the upper and lower end faces of the tongue pieces 555a and 555b. The press-fit stroke is determined by abutment of the end face of the vertical portion, thereby positioning the respective stationary contacts 6. 
     The armature 12a made of an electromagnetic soft-iron plate (thickness: 1 mm) has the projection 12b (diameter: 1 mm; height: 0.5 mm) formed by embossing at substantially its center, and is connected to the circular hole 88 formed in the movable spring 8. The pawl portion 12c of the armature 12a is formed by punching only half the plate thickness separately from the portion of the armature 12a which is formed into the projecting shape by press punching, and is used for positioning the armature 12a and the end face of the yoke 4a with each other. 
     The movable spring 8, the hinge springs 9, and the hinge spring fixing portion 10 are integrally press-punched from a high-conductive spring member having a thickness of 0.14 mm. The movable contact 7 is formed on the movable spring 8 by caulking, and thereafter the hinge springs 9 and the common terminal 11 are bent at predetermined angles, thereby forming the entire spring portion. A small circular hole 888 formed at substantially the center of the movable spring 8 is used for load characteristics inspection performed after the main body is completed. 
     FIG. 3 shows the main body of an electromagnetic relay according to the second embodiment of the present invention. In FIG. 3, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 3, cylindrical portions 111a and 111b for respectively accommodating a contact portion and hinge spring portions are formed on the two end portions of a spool 1b. With this structure, after the main body is assembled, the opening portions of the cylindrical portions 111a and 111b mate with the inner wall of the case in which the main body is to be mounted. The opening portion of the case is sealed with an epoxy-based adhesive, thereby remarkably improving insulation between the coil and the contact. 
     FIG. 4 shows the main part of the main body of an electromagnetic relay according to the third embodiment of the present invention and indicates another method of fixing the hinge spring portion. In FIG. 4, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 4, pins 112 are arranged on the one-end face of a spool 1c, and are engaged with holes 101 formed in the two sides of a hinge spring fixing portion 10. Thereafter, the pins 112 are deformed by heat stress to fix the hinge spring fixing portion 10. For example, the pins 112 made of a plastic are gradually squeezed in its axial direction with metal pins having flat end faces and heated to a high temperature, thereby fixing the hinge spring fixing portion 10. 
     FIG. 5 shows the main part of the main body of an electromagnetic relay according to the fourth embodiment of the present invention and indicates still another method of fixing the hinge spring portion. In FIG. 5, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 5, two end portions of a hinge spring fixing portion 10 are bent, and square window portions 102 are formed in the bent portions. Projecting portions 401 formed by half punching, like the pawl portion 12c shown in FIG. 2, are formed on the two sides of an upright portion 40a of a yoke 4b. Note that since the outward surfaces of the projecting portions 401 form curved surfaces, when the window portions 102 of the hinge spring fixing portion 10 engage with the window portions 102, the distal end of the hinge spring fixing portion 10 is slid along the surfaces of the projecting portions 401. Accordingly, the bending angle of the two end portions of the hinge spring fixing portion 10 is preferably an obtuse angle with respect to the surface of hinge spring fixing portion 10 which faces the spool. Clearance portions 99 are formed in the spool 1d for the projecting portions 401. 
     FIG. 6 shows the main part of the main body of an electromagnetic relay according to the fifth embodiment of the present invention having a structure as a combination of the first and third embodiments. In FIG. 6, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 6, a pair of opposing rod-shaped projecting pieces 113 similar to those in FIGS. 1 and 2, and pins 112 similar to those in FIG. 4 are formed on the one-end face of a spool 1e. 
     FIG. 7 shows the main part of the main body of an electromagnetic relay according to the sixth embodiment of the present invention and indicates another method of fixing the terminals. In FIG. 7, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 7, recessed portions 52a and 52b respectively formed on the vertical hang pieces of terminals 51a and 51b fit with projecting portions 30a and 30b formed on the end faces of a spool 1f with interference fit of several ten μm. 
     FIG. 8 shows the main body of an electromagnetic relay according to the seventh embodiment of the present invention for an improvement in the coil bobbin. In FIG. 8, the same portions as in FIGS. 1 and 2 are denoted by the same reference numerals, and a detailed description thereof will be omitted. Referring to FIG. 8, a pair of coil tie-up portions 33a and 33b exposed to the upper portion of a spool 1g are bent to oppose each other and are buried in a groove portion 34. With this structure, the height of the main body of the electromagnetic relay can be reduced. This arrangement is suitable for a structure in which the coil tie-up portions 33a and 33b are hermetically sealed with the inner wall of the case. In this case, the insulating performance between the coil and the contact can be further improved. 
     As has been described above, according to the present invention, the first effect is the low manufacturing cost. This is because the number of components is small, and because the assembling process and installation are simple. 
     The second effect is a high breakdown voltage. This is because the contact portion and the hinge portion are hermetically sealed with the cylindrical spool portion and the inner wall of the case, and because the opening portion of the case is sealed with epoxy-based adhesive. 
     The third effect is the compactness. This is because an extra space for fixing the yoke and the hinge spring fixing portion by caulking is not needed.