US3335375A

US3335375A - Electric switch device

Info

Publication number: US3335375A
Application number: US483977A
Authority: US
Inventors: Fujita Teizo
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-08-31
Filing date: 1965-08-31
Publication date: 1967-08-08
Anticipated expiration: 1984-08-08
Also published as: GB1082897A

Description

United States Patent 3,335,375 ELECTRIC SWITCH DEVICE Teizo Fajita, 334 Naka, Tezukayama, Sumiyoshi-ku, Osaka, Japan Filed Aug. 31, 1965, Ser. No. 483,977 Claims priority, application Japan, Aug. 31, 1964, 39/49,588 2 Claims. (Cl. 335-48) ABSCT OF THE DISCLOSURE An electrical switching structure capable of closing and opening the load path to protect the circuit and particularly provides auxiliary contact apparatus for indicating the interruption of excess currents and enabling the selfmaintenance of the operating circuits.

This invention relates to electric switch devices and more particularly to those designed for frequent opening and closing operations and also for interruption of unusual currents, such as occur in short-circuiting.

The present invention is intended to provide an electric switch device which not only functions as a frequentoperation switch, such as an electromagnetic switch usable, for example, to protect an electric motor when it is started and during its operation, but also functions as a circuit breaker to protect the distribution line from excess currents, such as are caused by short-circuiting and other circuit troubles.

According to the present invention, an electric switch device is provided which can operate instantaneously to electromagnetically interrupt any excess current as in short-circuiting or other troubles in the distribution line with such currents having magnitudes up to several times as high as that of the rated current of the device and which also can be operated as frequently as desired under normal circuit conditions to connect and disconnect the load in quite the same manner as ordinary electromagnetic switches, The switch device of the present invention can be utilized in place of the conventional combination of an electromagnetic switch with a circuit breaker to serve the purposes of connecting and disconnecting the load and protecting the circuit from short-circuiting troubles.

The inventiveswitch device has a general form closely resembling that of conventional electromagnetic switches and is extremely compact in construction. The component parts of the switch device will next be outlined. To afford an increased circuit-breaking capacity, switches are generally required to have a higher breaking speed and an increased breaking distance. Satisfaction of these requirements, however, tends to cause jumping of the switch contacts and to accelerate their wearing and welding together due to arcing. These phenomena should be avoided by all means with electromagnetic switches for frequent opening and closing operation while ensuring an extended period of service life of the switch. For the present purpose, therefore, it has been common practice to use a circuit breaker in combination with an electromagnetic switch, which conventionally has only a breaking capacity of the order of ten times the rated current.

According to the present invention, an increased breaking speed can be obtained by employing a releasable connection between the movable iron core of the operating electromagnet and the movable contact support memher, which together form an integral part movable as a unit for frequent opening and closing operation under normal circuit conditions, said connection between the movable iron core and movable contact support member being releasable upon occurrence of some circuit trouble or other to allow the latter member to travel at an increased speed separately from the former, which forms a major portion of the weight of the normally integral movable part. Also, according to the present invention, the delay time between the occurrence of a trouble and the actual circuit breaking is minimized by minimizing the route of tripping operation responding to the trouble so that any unusual current can be interrupted practically at the very instant of its occurrence.

According further to the present invention, the electric switch device has an increased breaking distance to serve as a circuit breaker, being arranged so'that the movable contact support member when released from the movable iron core is restored to an extended position lying beyond its position to which it is restored when operating together with the movable iron core under normal circuit conditions. In other words, the switch device is characterized in that it has a breaking distance for interruption of unusual currents differing from the distance over which the movable contact member traverses in frequent opening and closing operation under normal circuit conditions.

Also according to the present invention, the circuitbreaking operation can be visually indicated by a portion of the movable contact support member or an indicator member integrally mounted thereon which comes close to the indicating face of the switch casing when the support member is restored under an excess current to an extended position lying beyond that position to which the support member is restored under normal circuit conditions.

According to a further feature of the present invention, the switch device can be easily arranged to produce an alarm signal for each circuit-breaking operation by use of contacts arranged to be bridged to close a normally open alarm circuit when the movable contact support member is restored under an excess current to an extended position lying beyond that position to which it is restored under normal circuit conditions.

According to another feature of the present invention, the switch device is provided with auxiliary contact means operable in response to the descent of the movable contact support member to serve under normal circuit conditions as contacts for self-holding the operating circuit and, when an excess current is detected, as an operating switch to open the operating circuit. It will be apparent that use of such auxiliary contact means eliminates the need of providing any separate operating switch conventionally required to open the operating circuit in cases where contacts operable in association with the movable iron core are used to self-hold the operating circuit.

In addition, despite the use of such auxiliary contact means, the switch device can be kept free from any structural complicity and take a compact form convenient for wiring connections by arranging those auxiliary contact means operable in association with the movable iron core of the operating electromagnet on the side of the lower portion of the switch casing while arranging those operable in association with the movable contact support member on the sides of the upper portion of the switch casing.

According further to the present invention, the switch device can be reset simply by depressing a spring-loaded resetting pushbutton, which is effective to lower the movable contact support member, previously released under an excess current from the movable iron core and thus restored to an extended position lying beyond that to which the support member is restored under normal circuit conditions, thereby to re-establish the connection of the support member with the movable iron core.

The foregoing and other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, which illustrate one embodiment of the invention and in which:

FIG. 1 is a front elevational view, in cross-section, of the switch device embodying the present invention;

FIG. 2 is a side elevational view, in cross-section of the same;

FIG. 3 is a plan view of the switch device shown in FIGS. 1 and 2;

FIG. 4 is a fragmentary front elevational view, partly in cross section, of the essential portion of the switch device when in closed position; and

FIG. 5 is a view similar to FIG. 4 but illustrating the essential switch portion in its tripped position.

Referring to the accompanying drawings, reference numeral 1 indicates a switch casing formed of an insulating material and in which a fixed iron core 2, a spool 3 with an exciting coil 4 carried thereon and a movable iron core 5 are accommodated. A support rod 6 extends through the bottom portion of the fixed iron core 2 in the direction of core lamination with two leaf springs 7 and 8 interposed one between the spool 3 and support rod 6 and the other between the latter and the inner bottom of the casing 1 to resiliently support the fixed iron core 2. Projections 3a and 1a are formed on the bottom wall of the spool 3 and the inner bottom surface of the casing 1 to support the adjacent ends of the leaf springs 7 and 8, respectively. Extending through the top portion of the movable iron core 5 also in the direction of core lamination is a support rod 9 which is placed at each end on a movable contact support member 10a of an auxiliary switch 10. The support member 10a is resiliently supported by a spring 11 anchored to the bottom of the switch casing 1, biasing the movable iron core 5 upwardly by way of the support rod 9. The support member 1011 is formed with a window opening 10b in which

movable contact members

12 and 13 are resiliently supported by a spring 14. The

movable contact members

12 and 13 are disposed opposite to fixed

contact members

15 and 16 respectively, and thus can be brought into bridging contact therewith. Connecting

terminals

15a and 16a are secured to the respective fixed

contact members

15 and 16, as illustrated.

Reference numeral 17 indicates a fixed contact support or mounting firmly secured in place on top of the switch casing 1 with the movable iron core 5 normally cushioned on the bottom of the mounting 17 by means of elastic pads 18 fitted thereto. Fixed

contact members

19 and 20 are fixedly supported on said mounting 17 in opposed relation to a movable contact member 23, which is resiliently supported by a spring 22 on a support plate 21a, which in turn extends upwardly from a support member 21 for the movable contact member 23. Connecting

terminals

19a and 20a are secured to the fixed

contact members

19 and 20, respectively. Secured to the bottom of said support member 21 is an engaging lug or plate 24 which extends downwardly therefrom, and is formed with an engaging aperture 24a. A detent member 25 is pivotally mounted at the bottom on the support rod 9, which extends through the movable iron core, and has a bearing extension 25b and a detent lug 25a engageable in said aperture 24a formed in said engaging plate 24. A wire spring 26 is arranged to bias the detent member 25 in the direction to bring its lug 25a into engagement with said engaging aperture 24a. Another spring 27 is interposed between the support member 21 and the mounting 17 and is normally compressed with the support member 21 connected with the movable iron core 5 through the intermediary of the engaging plate 24 and detent member 25 to provide between the fixed and movable contact members 19-20 and 23 an appropriate space for proper operation of the device as an electromagnetic switch.

Reference numeral 28 indicates an overcurrent detecting device taking the form of an electromagnet operable under an excess current to trip the detent mechanism described above. The electromagnet 28 is embedded in the mounting block 17 immediately below one of the fixed contact members 19 and includes a fixed iron 29, a movable iron or plunger 31 supported thereon by way of a spring 30, and a tripping coil 32. The plunger 31 has a cap 31a fitted at one end thereof opposite to the bearing extension 25b of the detent member 25 and, when the magnet 28 is energized, is driven to the right as viewed in FIG. 1 to engage the bearing extension 25b so that the detent member 25 is rotated clockwise against the bias of spring 26 to disengage the detent lug 25a from the aperture 24a formed in the engaging plate 24. The tripping coil 32 of the electromagnet 28 is connected at its opposite ends to the adjacent fixed contact member 19 and the adjacent connecting terminal 19a, respectively.

The support member 21 carries a pair of contact pieces 33 fixed at its opposite longitudinal ends. The contact pieces are disposed opposite to respective fixed

contact pieces

34c and 34d secured to the mounting block 17 and are engageable with the respective fixed contact pieces when the support member 21 is lowered and when it is released to rise to an extended position to break the circuit, respectively. One of the movable contact pieces 33 and the adjacent fixed contact piece 340 together form a self-holding contact device 34a serving also as an operating switch while the other movable contact piece 33 and the adjacent fixed contact piece 34d together form an alarming contact device 34b operable upon interruption of an excess current to produce an alarm signal. Both the auxiliary contact devices 34a and 34b are normally open when the switch device is in its ofi state. As clearly seen in the drawings, not only the auxiliary switch 10 operable with the movement of the movable iron core 5 but also the auxiliary contact devices 34a and 34b are all arranged on the sides of the switch assembly to facilitate wiring connections thereto.

A frame box 35 is fixedly placed on the top of the mounting block 17 and carries a resetting pushbutton 37 which is resiliently supported on a spring 36 anchored to the bottom of the frame box. A cover 38 is fixed to the top of the frame box 35 and the resetting pushbutton 37 extends upwardly through the cover 38 to have its top surface exposed exteriorly. A viewing window 37a is formed in the top wall of the pushbutton 37 to enable visual confirmation of the tripping operation. The frame box 35 is formed with partition walls 35a to define a plurality of chambers 39 having arc-extinguishing shelves or fins 40 formed therein.

In the use of the present switch device, when the exciting coil 4 is energized the support member 21 is drawn downwardly together with the movable iron core 5 against the bias of springs 27 and '11, bringing the movable contact member 23 into contacting engagement with the

fixed contact members

19 and 20, as shown in FIG. 4. At the same time, one of the auxiliary contact means 34a is closed to self-hold the operating circuit and the supports 10a are lowered by the support rod 9 extending through the movable iron core 5 to operate the auxiliary switches 10. The circuit thus established and including

terminals

19a and 20a can be opened by de-energizing the exciting coil 4 to allow the support member 21 to be restored upwardly under the action of spring 27. Apparently, the self-holding auxiliary contact means 34a is opened at the same time.

The cyclic operation described above is apparently the same as that of ordinary electromagnetic switches.

When the switch device is in closed position as shown in FIG. 4, if an unusual current takes place having a magnitude not less'than ten times as high as the rated current, the tripping coil 32 of electromagnet 28 is energized to displace the movable iron or plunger 31 against the bias of spring 30. As the result, the cap 31 fitted to the forward end of the plunger is pressed against the bearing extension 25b of the detent member 25 to rotate the latter about the axis of the support rod 9 against the bias of spring 26 to such an extent that the detent lug 25a is disengaged from the aperture 24a formed in the engaging plate 24, which is integral with the support member 21. The support member 21 thus released from the movable iron core is raised under the action of spring 27 carrying the movable contact member 23 out of conducting engagement with the fixed

contact members

19 and 20, as shown in FIG. 5. On this occasion, it is to be noted that the support member 21 is severed from the movable iron core 5 practically at the very instant when the unusual current takes place. This is accounted for by the fact that the route of tripping operation responding to the overcurrent is minimized including no particular mechanism other than the detent member directly actuatable by the overcurrent-detecting electromagnet. As long as the support member 21 is connected with the movable iron core 5, the contact separation between the movable and fixed contact members 23 and 19-20 is maintained at a distance appropriate for functioning as an electromagnetic switch since rise or restoring movement of the movable iron core 5 is limited by the pads 18 fitted to the mounting '17. On this occasion, it is to be noted that the alarming auxiliary contact device 34b is held open as its movable contact piece 33 cannot approach the adjacent fixed contact piece 34d any distance beyond a point determined by the limited rise of the movable iron core. When the support member 21 is released from the movable iron core under an unusual current, however, the support member rises over an extended distance until the alarming contact device 3412 is closed. In this manner, any unusual current can be interrupted effectively with such increased contact separation, the auxiliary alarm contact device 3412 closing an alarm circuit to send an alarm signal.

In other words, the breaking distance of the switch device when the electromagnet 29 is energized by an unusual current is the sum of the distance over which the movable iron core 5 travels in normal opening and closing operation and the minimum distance between the movable and fixed

contact pieces

33 and 34d of the alarm contact device 34b, which is inoperative under normal circuit conditions. Under an excess current, the detent mechanism including the engaging plate 24 depending from the support member 21 and the detent member 25 mounted on the movable iron core 5 is tripped to allow the support member 21 to be restored to an extended position thus giving to the switch device an increased breaking distance enough to effectively interrupt the excess current.

Upon restoration of the support member 21 to the extended position, the self-holding contact device 34a previously closed upon descent of the support member 21 is opened to cancel its self-holding efiect upon the operating circuit. The exciting coil 4 being thus de-energized, the movable iron core 5 now released from the support member 21 is raised under the bias of the springs 11, supporting auxiliary switches 10, simultaneously allowing the latter to restore their normal position. If the auxiliary switches 10 operable in response with the movement of the movable iron core be employed to serve the self-holding purpose, the movable iron core 5 would be held attracted in its lower position even when the main circuit has been interrupted upon restoration of the support member 21 to its extended position since the operating circuit remains closed and thus it would be necessary to use some separate operating switch to open the operating circuit. Such separate operating switch is not required with the present switch device since it utilizes the auxiliary contact device 34a, arranged in association with the support member 21, for the self-holding purpose. In this connection, it will be noted that, even when the movable iron core 5 is restored to its upper normal position upon current interruption, the detent lug 25a of the detent member 25 is not engaged by the aperture 24a formed in the engaging plate 24, now additionally raised to its highest position, but is only pressed against the latter below the aperture 24a, as shown in FIG. 5. Under this condition, it will be apparent the main circuit cannot be completed even when the exciting coil 4 is energized.

In the tripped state of the switch device, the top end of the support plate 21a upstanding from the support member 21 lies close to the resetting button 37 to be clearly observed through the viewing window 37a formed therein, as clearly shown in FIG. 5. If desired, an appropriate indicating member may be affixed to the top of the support plate 21a to aid in external observation of the tripping operation.

To restore the present switch device for reclosing after the circuit trouble has been eliminated, it is only required to depress the resetting pushbutton 37 against the bias of spring 36. On this occasion, the support plate 21a with its top end positioned close to the bottom of the resetting pushbutton 37 is simultaneously lowered together with the support member 21.

Therefore, one of the movable contact pieces 33 carried on the support member 21 is separated from the adjacent fixed contact piece 34d to open the alarm circuit. On the other hand, the engaging plate 24 depending from the support member 21 is lowered until the engaging aperture 24a formed in the plate 24 is placed in alignment with the detent lug 25a pressed against the latter to allow the lug 25a to engage the aperture 24a under the bias of wire spring 26. When the detent mechanism has been reset in this manner, the resetting pushbutton 37 is released and the entire device is restored to its normal position ready for reclosing, with the support member 21 now connected with the movable iron core 5, as shown in FIG. 1. In the above resetting operation, the self-holding auxiliary contact device 34a is not closed but its contact distance is reduced relative to that given when the support member 21 is in its extended position.

It will be appreciated from the foregoing description that according to the present invention an electric switch device is provided which is highly valuable in practical applications functioning as a long-life electromagnetic switch for frequent opening and closing operation and also as a circuit breaker capable of instantaneous interruption of unusual excess currents.

Though one preferred embodiment of the present invention has been shown and described herein, it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. For example, though in the embodiment illustrated the engaging plate 24 and detent member 25 are mounted on the support member 21 and movable iron core 5, respectively, they can be mounted, contrariwise, on the movable iron core 5 and support member 21, respectively, with the same result. Also, it is of course possible to obtain a time delay overcurrent-interrupting operation by employing a thermal relay or the like in combination or replacing the electromagnet 28 by an oil dash-pot. Further, the electromagnet device 28 may be used solely to serve as a driving mechanism for actuating the detent member by eliminating the tripping coil 32. In this case, the movable iron or plunger 31 functions only as an actuating rod supported on the spring 30 with a separate overcurrent detecting device mounted on the casing exteriorly thereof. With such arrangement, it will be apparent that the overcurrent detecting device can readily be replaced when desired. Also, the bimetal member of the thermal relay may be arranged to directly drive the actuating rod to trip the detent mechanism, thereby eliminating the need of providing any contacts on the thermal relay specifically for the circuit-breaking purpose.

What is claimed is:

1. An electric switch device comprising a fixed contact member, a movable contact member, an operating electromagnet having a movable core, a support'memher for said movable contact member operated by said movable core, a coupling mechanism releasably coupling said movable core and said support member, an overcurrent detecting device for releasing the coupling of said support member and said core in response to excess current through-said contact members, said over-current detecting device being operated by said operating electromagnet when said support member and said movable core are coupled by said mechanism during normal operation of said switch device only at the time when excess current is generated, said coupling being released corresponding to the operation of said over-current detecting device whereby said coupling is released and the excess current of said switch device is interrupted, the open distance from said movable contact member to said fixed contact member at the time of excess current interruption being made greater than the open distance from said fixed contact member to said movable contact member during normal switching operation, an auxiliary movable contact member affixed to said support member, an auxiliary fixed contact member for closing with said auxiliary movable contact member only when said support member has returned to an expanded position for interruptin excess current, and means comprising a specific contact device for reporting the excess current interrupting operation.

2. An electric switch device comprising a fixed contact member, a movable contact member, an operating electromagnet having a movable core, a support mem- 'ber for said movable contact member operated by said movable core, a coupling mechanism for releasing the coupling of said movable core and said support member, an over-current detecting device for releasing the coupling of said support member and said core when excess current is generated through said contact members, said over-current detecting device being responsive to and operated by said operating electromagnet when said support member and said movable core are coupled by said mechanism at the normal operation of said switch device, said coupling being released only at the time when excess current is generated correspond ing to the operation of said over-current detecting device whereby said coupling is released and the excess current of said switch device is interrupted, the open distance from said movable contact member to said fixed contact member at the time of excess current interruption being made greater than the open distance from said fixed contact member to said movable contact member at the time of normal switching operation, an auxiliary switch secured to said movable core and responsive directly to operation of said movable core, an auxiliary movable contact member being affixed to said contact member support independent of said auxiliary switch, an auxiliary fixed contact member closing with said auxiliary movable contact member only at the time of the closing operation of said support, thereby comprising a contact device specifically for self-supporting the operating electromagnet.

References Cited FOREIGN PATENTS 964,969 5/1957 Germany.

BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner. I

Claims

1. AN ELECTRIC SWITCH DEVICE COMPRISING A FIXED CONTACT MEMBER, A MOVABLE CONTACT MEMBER, AN OPERATING ELECTROMAGNETIC HAVING A MOVABLE CORE, A SUPPORT MEMBER FOR SAID MOVABLE CONTACT MEMBER OPERATED BY SAID MOVABLE CORE, A COUPLING MECHANISM RELEASABLY COUPLING SAID MOVABLE CORE AND SAID SUPPORT MEMBER, AN OVERCURRENT DETECTING DEVICE FOR RELEASING THE COUPLING OF SAID SUPPORT MEMBER AND SAID CORE IN RESPONSE TO EXCESS CURRENT THROUGH SAID CONTACT MEMBERS, SAID OVER-CURRENT DETECTING DEVICE BEING OPERATED BY SAID OPERATING ELECTROMAGNET WHEN SAID SUPPORT MEMBER AND SAID MOVABLE CORE ARE COUPLED BY SAID MECHANISM DURING NORMAL OPERATION OF SAID SWITCH DEVICE ONLY AT THE TIME WHEN EXCESS CURRENT IS GENERATED, SAID COUPLING BEING RELEASED CORRESPONDING TO THE OPERATION OF SAID OVER-CURRENT DETECTING DEVICE WHEREBY SAID COUPLING IS RELEASED AND THE EXCESS CURRENT OF SAID SWITCH DEVICE IS INTERRUPTED, THE OPEN DISTANCE FROM SAID MOVABLE CONTACT MEMBER TO SAID FIXED CONTACT MEMBER AT THE TIME OF EXCESS CURRENT INTERRUPTION BEING MADE GREATER THAN THE OPEN DISTANCE FROM SAID FIXED CONTACT MEMBER TO SAID MOVABLE CONTACT MEMBER DURING NORMAL SWITCHING OPERATION, AN AUXILIARY MOVABLE CONTACT MEMBER AFFIXED TO SAID SUPPORT MEMBER, AN AUXILIARY FIXED CONTACT MEMBER FOR CLOSING WITH SAID AUXILIARY MOVABLE CONTACT MEMBER ONLY WHEN SAID SUPPORT MEMBER HAS RETURNED TO AN EXPANDED POSITION FOR INTERRUPTING EXCESS CURRENT, AND MEANS COMPRISING A SPECIFIC CONTACT DEVICE FOR REPORTING THE EXCESS CURRENT INTERRUPTING OPERATION.