Abstract:
The electromagnetic relay has a pair of normally closed and normally open fixed terminals which are disposed opposing each other. At least two normally closed fixed contacts are mounted on the normally closed fixed terminal, and at least two normally open fixed contacts are mounted on the normally open fixed terminal. The normally closed and normally open fixed terminals are commonly used by a plurality of relay units. Therefore, the relay can be small enough to be installed on a small area, and allows high-density electric circuits to be provided on circuit boards.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an electromagnetic relay which has a plurality of relay units, and more particularly to an electromagnetic relay which has a pair of normally closed and normally open terminals on which at least two fixed contacts are mounted. 
     When a d.c. motor is rotated in alternate directions, two electromagnetic relays are required: one is for the clockwise direction and the other for the counterclockwise. This is also true for the case in which a polar solenoid is activated in alternate directions. 
     Conventional electromagnetic relays, however are separated from each other. Therefore, each conventional electromagnetic relay independently requires its own wiring pattern to provide an electric circuit for operating motors or polar solenoids in alternate directions. This results in complicated wiring patterns on a printed circuit board and requires a very long time and high cost to design them. 
     In addition, these separated electromagnetic relays independently require an area to be electrically insulated from the other electric components on the circuit board. This causes a large area to be used and hinders designers from providing high-density circuits. Moreover, since the relays independently require their own components, they are expensive. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of this invention to provide an electromagnetic relay which allows simplified wiring patterns. 
     It is another object of this invention to provide an electromagnetic relay which allows the wiring patterns to be provided at low cost. 
     It is still another object of this invention to provide an electromagnetic relay which can be installed on a small area and allows high-density electric circuits on circuit boards. 
     It is still another object of this invention to provide an electromagnetic relay which itself can be manufactured at low cost. 
     According to this invention, there is provided an electromagnetic relay which includes at least two electromagnet devices, each having a coil device, a pair of normally closed and normally open fixed terminals which are disposed opposing each other, at least two normally closed fixed contacts mounted on the normally closed fixed terminal, at least two normally open fixed contacts mounted on the normally open fixed terminal, each of the normally open fixed contacts opposing each of the normally closed fixed contacts, and at least two movable contacts, each of which is reciprocated between the normally closed and open fixed contacts by activating and deactivating the electromagnet devices. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a disassembled electromagnetic relay of a first embodiment of this invention; 
     FIG. 2 is a front view of an electromagnetic relay of a first embodiment of this invention; 
     FIG. 3 is a front view of an electromagnetic relay of a second embodiment of this invention; 
     FIG. 4 is an electric circuit configuration connected to a motor for illustrating an application of the electromagnetic relay of FIG. 1; 
     FIG. 5 is an electric circuit configuration for illustrating the operation of the electromagnetic relay of FIG. 4; 
     FIG. 6 is another electric circuit configuration for illustrating the operation of the electromagnetic relay of FIG. 4; 
     FIG. 7 is a perspective view of an electromagnetic relay of a third embodiment of this invention; 
     FIG. 8 is an electric circuit configuration of the electromagnetic relay of FIG. 7 which is connected to a motor; 
     FIG. 9 is an electromagnetic relay of a fourth embodiment of this invention; 
     FIG. 10 is an electric circuit configuration of the electromagnetic relay of FIG. 9 which is connected to a motor; 
     FIGS. 11a and 11b shown an electromagnetic relay of a fifth embodiment of this invention; 
     FIGS. 12a and 12b shown an electromagnetic relay of a sixth embodiment of this invention; 
     FIGS. 13a and 13b shown an electromagnetic relay of a seventh embodiment of this invention; 
     FIGS. 14a and 14b shown an electromagnetic relay of an eighth embodiment of this invention; 
     FIG. 15 is an electromagnetic relay of a ninth embodiment of this invention; 
     FIG. 16 is an electromagnetic relay of a tenth embodiment of this invention; 
     FIG. 17 is a perspective view of a disassembled electromagnetic relay of an eleventh embodiment of this invention; 
     FIG. 18 is a front view of an electromagnetic relay of a twelfth embodiment of this invention; 
     FIG. 19 is a schematic diagram of an electromagnetic relay of a thirteenth embodiment of this invention; 
     FIG. 20 is a perspective view of the fixed contacts used in the electromagnetic relay of FIG. 19; 
     FIG. 21 is a side view of an electromagnetic relay of a fourteenth embodiment of this embodiment; 
     FIG. 22 is an electric circuit configuration connected to a motor for illustrating an application of the electromagnetic relay of FIG. 19; 
     FIG. 23 is an electric circuit configuration for illustrating the operation of the electromagnetic relay of FIG. 22; 
     FIG. 24 is another electric circuit configuration for illustrating the operation of the electromagnetic relay of FIG. 22. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 show an electromagnetic relay A as a first embodiment of this invention. [Whole Construction] 
     The electromagnetic relay A has an electromagnet unit 1, a fixed contact unit 3, a yoke unit 4, an iron core unit 5, and a movable unit 6. [The Electromagnet Unit] 
     The electromagnet unit 1 has two electromagnet devices 10a and 10b. The device 10a has a spool 11a which is made of a main frame 12a, and two flanges 13a and 13a formed at both ends thereof. A pair of coil terminals 15a and 15a is fixed to the lower flange 13a. Wound around the spool 11a is a coil 14a whose one end is connected to one of the coil terminals 15a and whose other end is connected to the other of the terminals 15a. The construction of the device 10b is the same as that of the device 10a. Formed on the front part of the upper flange 13a is a terminal base 21a which has two terminal grooves 22a and 23a paralleling each other. Also, A terminal base 21b, which has two terminal grooves 22b and 23b paralleling each other, is formed on the front part of the upper flange 13b. The terminal bases 21a and 21b form a terminal unit 20. [The Fixed Contact Unit] 
     The fixed contact unit 3 is made of inverted L-shaped normally open and closed fixed terminals 31a and 31b. The terminal 31a has two normally open fixed contacts 34a and 35a which are disposed on a flat portion 32a of the terminal 31a. The other terminal 31b has two normally closed fixed contacts 34b and 35b which are disposed on a flat portion 32b of the terminal 31b. The contact 34a opposes the contact 34b and the contact 35a opposes the contact 35b, respectively. [The Yoke Unit] 
     The yoke unit 4 is made of L-shaped yokes 41a and 41b, on the flat portions 42a and 42b of which iron core fixing openings 43a and 43b are formed, respectively. Perpendicular portions 44a and 44b have openings 45a and 45b to fix the movable unit 6 which is described hereinafter. [The Iron Core Unit] 
     This unit 5 has iron cores 51a and 51b which have respective magnetic pole surfaces 52a and 52b at the upper ends, and respective fixing tips 53a and 53b at the lower ends. [The Movable Unit] 
     The movable unit 6 is made of two inverted L-shaped resilient movable contact members 61a and 61b. The movable contact members 61a and 61b have flat portions 62a and 62b on which movable iron plates 67a and 67b are fixed by caulking protrusions 68a and 68b disposed on the flat portions 62a and 62b. Movable contacts 63a and 63b are disposed on the tips of the flat portions 62a and 62b. Perpendicular portions 64a and 64b have openings 66a and 66b and their lowest edges partly extend downwardly to form common terminals 65a and 65b. [Assembly Procedure] 
     The flat portions 42a and 42b of the yoke unit 4 are disposed on the lower surfaces of the flanges 13a and 13b. The fixing tips 53a and 53b of the iron cores 52a and 52b are inserted into the openings 43a and 43b through the main frames 12a and 12b and are caulked to make the electromagnet unit 1. 
     Next, the flat portions 32a and 32b of the normally open and normally closed terminals 31a and 31b are pressed into the grooves 22a and 22b of the terminal bases 31a and 31b, so that the fixed contacts 34a and 34b oppose the fixed contacts 35a and 35b, respectively. 
     The perpendicular portions 64a and 64b of the movable contact members 61a and 61b are disposed behind the yokes 41a and 41b in such a manner that the openings 66a and 66b face the openings 45a and 45b. Then, the movable contact members 61a and 61b are tightened to the perpendicular portions 64a and 64b respectively by screws, not shown, fixed into the openings 45a, 66a, 45b, and 66b. Consequently, as shown in FIG. 2, the movable contact 63a is not only disposed between the fixed contacts 34a and 34b but also contacted with the upper fixed contact 34b by the resilience of the movable contact member 61a. Also, the movable contact 63b is disposed between the fixed contacts 35a and 36b, and is contacted with the fixed contact 35b by the resilience of the movable contact member 61b. The iron plates 67 a and 67b oppose the magnetic pole surfaces 52a and 52b of the iron cores 51a and 51b, respectively. 
     Thus, the electromagnet unit 1, the fixed contact unit 3, the yoke unit 4, the iron core unit 5, and the movable unit 6 are assembled to make the single electromagnetic relay A having two relay units R 1  and R 2  as shown in FIG. 2. [Operation] 
     The operation of the electromagnetic relay A will be described hereinafter referring to FIGS. 1 and 2. When a voltage is applied across the coil terminals 15a and 15a of the relay unit R 1 , the iron core 51a is energized, thereby the movable iron plate 67a is attracted to the magnetic pole surface 52a, and the movable contact 63a breaks contact with the normally closed fixed contact 34b and contacts with the normally open fixed contact 34a. Thus, an electric circuit connecting the normally open fixed terminal 31a to the common terminal 65a is provided. 
     By contrast, when the iron core 51a is deactivated by cutting off the current to the coil 41a, the movable contact 63a returns upwardly to contact with the normally closed fixed contact 34b with the aid of the resilience of the movable contact member 61a, providing an electric circuit which connects the normally closed fixed terminal 31b to the common terminal 65a. 
     The operation of the relay unit R 2  is not described because it is the same as that of the relay unit R 1 . [Application] 
     An application of the relay A will be described hereinafter referring to FIGS. 4 to 6. FIGS. 4 to 6 show an application in which the relay A (which is encompassed by a line 1) is used to rotate a d.c. motor 100 in alternate directions. 
     In FIG. 4, one of the coil terminals 15a and 15a of the relay unit R 1  is connected to the plus terminal pt of a d.c. power supply, not shown, via a switch SW 1 , and the other is connected to the minus terminal mt. In addition, one of the coil terminals 15b and 15b of the relay unit R 2  is connected to the plus terminal pt via a switch SW 2 , and the other is to the minus terminal mt. The normally closed fixed terminal 31b is connected to the minus terminal and the normally open fixed terminal 31a is to the plus terminal, respectively. The common terminal 65a of the relay units R 1  is connected to one pole of the motor 100 and the common terminal 65b of the relay unit R 2  is to the other pole. 
     As shown in FIG. 4, before the operation of the motor 100, both the switches SW 1  and SW 2  are turned off and the poles of the motor 100 are both short-circuited to the minus terminal. The two poles, however, are disconnected from each other when either SW 1  or SW 2  is turned on. 
     In operation, as shown in FIG. 5, when the switch SW 2  is turned on with the switch SW 1  turned off, the movable contact 63b of the relay unit R 2  breaks contact with the normally closed fixed contact 35b and contacts the normally open fixed contact 35a. Consequently, a current flows in direction P to rotate the motor 100 into the forward direction. 
     By contrast, as shown in FIG. 6, when the switch SW 1  is turned on with the switch SW 2  turned off, the movable contact 63a of the relay unit R 1  breaks contact with the normally closed fixed contact 34b and contacts the normally open fixed contact 34a, so that the current flows into the reverse direction P&#39; to rotate the motor 100 into the opposite direction. 
     The electromagnetic relay A as the first embodiment has the two relay units R 1  and R 2 . However, an electromagnetic relay A 2  as a second embodiment of this invention has four relay units R 1 , R 2 , R 3  and R 4  which have common normally open and normally closed fixed terminals 31a and 31b (FIG. 3). A movable contact 63c of the relay unit R 3  is reciprocated between fixed contacts 36a and 36b, and a movable contact 63d is between fixed contacts 37a and 37b, controlling a current flowing via common terminals 65c and 65d. 
     In the first and second embodiments, both ends of the coil 14a are connected to the coil terminals 15a and 15a, and those of the coil 14b are to the coil terminals 15b and 15b. However, as shown in FIG. 7, in an electromagnetic relay A 3  as the third embodiment of this invention, the normally open fixed terminal 31a has a coil connecting protrusion 70, to which one end of the coil 14a and that of the coil 14b are connected. Accordingly, the relay unit R 1  has only one coil terminal 15a and the unit R 2  has only one coil terminal 15b, so that the construction of the coil terminals is simple and the wiring can be easily performed. 
     An application of the relay A 3  will be described hereinafter referring to FIG. 8. FIG. 8 shows an electric circuit of the relay A 3  which is used to rotate the d.c. motor 100 in alternate directions. 
     When only the switch SW 1  is turned on, the movable contact 63a of the relay unit R 1  breaks contact with the normally closed fixed contact 34b and contacts the normally open fixed contact 34a, so that the current flows into the direction P to rotate the motor 100 into the forward direction. 
     On the contrary, when only the switch SW 2  is turned on, the movable contact 63b of the relay unit R 2  breaks contact with the normally closed fixed contact 35b and contacts with the normally open fixed contact 35a, so that the current flows into the reverse direction P&#39; to rotate the motor 100 into the opposite direction. 
     As shown in FIG. 9, in an electromagnetic relay A 4  as the fourth embodiment of this invention, the normally open fixed terminal 31a has a coil connecting protrusion 71a, and the normally closed fixed terminal 31b has a coil connecting protrusion 71b. One end of the coil 14a of the relay unit R 1  is connected to the protrusion 71a, and the other end is connected to the coil terminal 15a. Also, one end of the coil 14b of the relay unit R 2  is connected to the protrusion 71b, and the other end is connected to the coil terminal 15b. 
     FIG. 10 shows an electric circuit of the relay A 4  which is used to rotate the motor 100 in alternate directions. 
     When the switch SW 1  is turned on to activate the relay unit R 1 , the current flows into the direction P to rotate the motor 100 in the forward direction. On the other hand, when the switch SW 2  is turned on to activate the relay unit R 2 , the current flows in direction P&#39; to rotate the motor 100 into the opposite direction. 
     In the foregoing embodiments, the relays A to A 4  are used to rotate the motor 100 in alternate directions. However, they can be used to activate polar solenoids in alternate directions. In addition, the terminal bases 21a and 21b may be made separately from the flanges 13a and 13b, mounted on the coil devices 10a and 10b, and fixed using the iron cores 51a and 51b along with the fixed contact unit 3. Moreover, the normally open and normally closed fixed terminals 31a and 31b along with the terminal grooves 22a, 22b, 23a, and 23b may be formed as shown in FIGS. 11a to 16 so that the terminals 31a and 31b can be precisely positioned and prevented from coming off easily from the terminal grooves. 
     In FIGS. 11a and 11b, the tips of the flat portions 32a and 32b of the terminals 31a and 31b are bent downwardly to form protrusions 36a and 36b. The terminal bases 21a and 21b have recesses into which the protrusions 36a and 36b are fitted. In addition, the upper part of the perpendicular portions 33a and 33b can be pressed into the terminal grooves as well as the flat portions 32a and 32b. 
     In FIGS. 12a and 12b, the terminal 31a has protrusions 37a and 37a extending upwardly. The terminal 31b has a protrusion 36b extending downwardly to engage the side of the terminal base 21a and steps 37b and 37b formed on the flat portion 32b. Also, the terminal base 21b has recesses, not shown, into which the protrusions 37a are fitted. 
     In FIGS. 13a and 13b, the flat portion 32a has protrusions 38a and 38a extending in the direction into which the terminal 31a is pressed. Also, the flat portion 32b has protrusions 38b and 38b extending in the same direction as that of the protrusions 38a and 38a.  The grooves 22a, 22b, 23a and 23b have recesses, not shown, corresponding to the protrusions 38a and 38b. 
     In FIGS. 14a and 14b, the flat portion 32a has protrusions 39a and the flat portion 32b has protrusions 39b, respectively. The grooves 22a, 22b, 23a, and 23b are formed from the rear side of the terminal bases 21a and 21b, and have recesses, not shown, corresponding to the protrusions 39a and 39b. 
     In FIG. 15, another terminal base 24 is formed to support the central parts of the flat portions 32a and 32b. Therefore, the distance between the flat portions 32a and 32b, that is, the stroke of the movable contacts 63a and 63b is kept constant, allowing the stable operation of the electromagnetic relay. 
     In FIG. 16, instead of the terminal base 21a, a small-sized terminal base 25a is formed to support only the normally open fixed contact 31a. Though the tip of the flat portion 32b is not supported by the base 25a, the relay can operate stably because the terminal base 24a supports around the central parts of the flat portions 32a and 32b to keep the stroke constant. 
     FIG. 17 shows an electromagnetic relay as still another embodiment of this invention. The flanges 11a and 12a are extended in the width direction. 
     The flange 11a has a recess 15c formed on the upper portion thereof, and the flange 12a has a recess 17c which is formed on the lower portion of the flange 12a opposing the recess 15c. 
     The electromagnet device 10b has the main frame 13b, and the flanges 11b and 12b. Wound around the main frame 13b is the coil 14b whose one end is connected to one of the coil terminals 19b and whose other end is to the other of the terminals 19a. The flanges 11b and 12b are slided into the recesses 15c and 17c to fix the device 10b, so that the distance between the coils 14a and 14b are kept constant and the operation of the relay is stable. The other constructions and assembly procedures are the same as those of the relay shown in FIG. 1. 
     In this embodiment, the terminal unit 20 is made separately from the flange 12a. However, as shown in FIG. 18, the flange 12a may include a terminal base 21a which has the terminal grooves 22a and 23a, and a terminal base 21b which has the terminal grooves 22b and 23b. 
     FIG. 19 shows an electromagnetic relay A 5  as another embodiment of this invention The relay A 5  has two relay units Ra and Rb which are made of a base 200, a contact unit 8, and two electromagnet devices 9a and 9b. 
     As shown in FIG. 20, the contact unit 8 has T-shaped normally closed and normally open fixed terminals 81 and 83. Normally closed fixed contacts 82a and 82b are disposed on the upper flat portion of the terminal 81, and normally open fixed contacts 84a and 84b are on the upper flat portion of the terminal 83, respectively. The distance between the contacts 82a and 82b is equal to that between the contacts 84a and 84b. A generally c-shaped common terminal 85a has two common contacts 86a opposing each other, and also a generally c-shaped common terminal 85b has two common contacts 86b opposing each other. The common terminal 85a is disposed on the left side of the terminals 81 and 83 in such a manner that the axis of the contacts 86a is in parallel with that of the contacts 82a and 84a. The common terminal 85b is disposed on the right side of the terminals 81 and 83 in such a manner that the axis of the contacts 86b is in parallel with that of the contacts 82b and 84b. 
     A movable contact member 87a supporting the movable contacts 88a and 89a is disposed so that the contact 88a can reciprocate between the fixed contacts 86a, and the contact 89 can reciprocate between the fixed contacts 82a and 84a. A movable contact member 87b supporting the movable contacts 88b and 89b is disposed so that the contact 88b can reciprocate between the fixed contacts 86b, and the contact 89b can reciprocate between the fixed contacts 82b and 84b. 
     When the electromagnet devices 9a and 9b are not activated, the movable contacts 88a and 89a contact with the fixed contacts 86a and 82a, and the movable contacts 87b and 88b contact with the fixed contacts 82b and 86b. 
     The electromagnet device 9a is made of an electromagnet 91a, a generally L-shaped yoke 95a, and a generally L-shaped movable iron member 96a. The electromagnet 91a is made of an iron core 92a, a spool 93a into which the iron core 92a is inserted, and a coil 94a which is wound around the spool 93a. The Yoke 95a is fixed to the electromagnet 91a, and the movable iron member 96a having a protrusion 97a is mounted on the electromagnet 91a so that it can rotate in the directions of a and a&#39; around one end of the yoke 95a a supporting point, when a current is applied to the coil 94a. The construction of an electromagnet device 9b is the same as that of the electromagnet device 9a. The electromagnets 9a and 9b are activated independently from each other. 
     When the electromagnet 91a is energized, the movable iron member 96a is rotated in the a direction around one end of the yoke 95a, and the protrusion 97a pushes up the movable contact member 87a so that the movable contacts 88a and 89a can contact with the fixed contacts 86a and 84a, respectively. On the other hand, when the electromagnet 91b is energized, the movable contacts 88b and 89b of the movable contact member 87b contact with the fixed contacts 86b and 84b, respectively. 
     The distance between the common terminal 85a and the normally closed fixed terminal 81, and the distance between the common terminal 85a and the normally open fixed terminal 83 are adjusted according to the current level flowing through the terminals 81, 83 and 85a. For example, when a high-level current is used, the distance between the terminals 85a and 81, and the distance between the terminals 85a and 83 are set longer. This is true for the common terminal 85b. The distance between the contacts opposing each other, for example, 82a and 84a, need not be changed even if the current level is changed. 
     An application of the relay A 5  will be described hereinafter referring to FIGS. 22 to 24. FIGS. 22 to 24 show an application in which the relay A 5  is used to rotate the d.c. motor 100 in alternate directions. 
     As shown in FIG. 22, before the switches SW 1  and SW 2  are turned on, the normally closed fixed terminal 81 is connected to the plus terminal pt of a d.c. power supply, not shown, and the normally open fixed terminal 83 to the minus terminal mt. The common terminal 85a is connected to one pole of the motor 100, and the common terminal 85b to the other pole. One end of the coil 94a is connected to the minus terminal mt, and the other end is connected the plus terminal pt via the switch SW 1 . In addition, one end of the coil 94b is connected to the minus terminal mt, and the other end is to the plus terminal pt via the switch SW 2 . 
     In operation, when the switch SW 1  is turned on with the switch SW 2  turned off the electromagnet device 9a is activated. Thereby, the movable contacts 88a and 89a contact with the common contact 86a and the fixed contact 84a, connecting the normally open fixed terminal 83 to the common terminal 85a. Thus, an electric circuit as shown in FIG. 5 is provided. Consequently, the plus terminal of the power supply is connected to the one pole of the motor 100 via the terminal 83, the movable contact member 87a, and the common terminal 85a. Also, the minus terminal mt is connected to the other pole of the motor 100 via the terminal 81, the movable contact member 87b,  and the terminal 85b. Therefore, an electric current flows in the direction P to rotate the motor 100 in the forward direction. 
     On the other hand, when the switch SW 2  is turned on with the switch SW 1  turned off, the electromagnet device 9b is activated. Thereby, the movable contacts 88b and 89b contact with the common contact 86b and the fixed contact 84b respectively, connecting the terminal 83 to the common terminal 85b. Thus, an electric circuit as shown in FIG. 6 is provided. Consequently, the plus terminal pt is connected to the other pole of the motor 100 via the terminal 83, the movable contact member 87b, and the terminal 85b. Also, the minus terminal mt is connected to the one pole via the terminal 81, the movable contact member 87a, and the terminal 85a. Therefore, the electric current flows in the direction P&#39; to rotate the motor in the reverse direction. 
     In this embodiment, the movable contact members 87a and 87b are made separately from the electromagnet devices 9a and 9b, and moved by the protrusions 97a and 97b. However, as shown in FIG. 21, the member 87a may be fixed to the movable iron member 96a so that the member 87a can be moved together with the iron member 96a. Also, the member 87b may be fixed to the movable iron member 96b, not shown, so that the member 87b can be moved together with the iron member 96b. 
     It should be understood that the above description is merely illustrative of this invention and that many changes and modifications may be made by those skilled in the art without departing from the scope of the appended claims.