US2751451A

US2751451A - Snap switch

Info

Publication number: US2751451A
Application number: US370992A
Authority: US
Inventors: Robert B Bradstock; Wyndham R Hickin
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1953-07-29
Filing date: 1953-07-29
Publication date: 1956-06-19
Anticipated expiration: 1973-06-19

Description

June 19, 1956 R. B. BRADSTOCK ET AL 2,751,451

SNAP SWITCH 2 Sheets-Sheet 1 Filed July 29. 1953 k mm i uw e s i n Fawn F R m n -%t e w A v a nth .m ra W en n T U. R b w 5 Q F June 19', 1956 R. B. BRADSTOCK ET AL SNAP SWITCH 2 Sheets-Sheet 2 Filed July 29, 1953 Inventors: Robert B. Bradstock,

Wyndham R. Hickm, b5 wfim T hei r- Att or-nes.

Patented June 19, 1956 SNAP SWITCH Robert B. Bradstock and Wyndham R. Hiclrin, Erie, lfa., assignors to General Electric Company, a corporation of New York Application July 29, 1953, Serial No. 370,992

8 Claims. (Cl. 200-40) This invention relates to snap switches and more par ticularly to an improved means for insuring positive snap action.

In many switch applications it is necessary that the contacts be separated by a positive snap action providing for separation of the contacts at such a high speed that arcing will be reduced to a minimum. It is therefore desirable that means be provided to prevent the. actuation of a snap mechanism in a switch until the contact carrying member is biased away from the closed position.

An object of this invention is to provide a simple and reliable snap switch with a latchmechanism for preventing operation of the contact carrying member during either closing or opening of the switch until after .the snap springs have'been stressed a predetermined. amount.

A further object is to provide a contact carrying member that will pivot the contact members both beforebreaking contact in opening and after making contact in closing, thus providing a wiping action.

Briefly stated, in carrying out this invention in one form, a latch mechanism having two engaging latch members is provided. One member of the latch mechanism is attached to the movable contact carrier and the other member of the latch mechanism is attached to the operating member of the switch. When the operating member is moved to actuate the contact carrier, the latch members are initially in engagement for a predetermined distance during which the operating springs are stressed and thereafter the latch members disengage to release the contact carrying member for high speed movement to the open or closed position. Another feature of this invention is the pivot mounting of the contact members on the movable contact carrier. This mounting allows the contact carrier to move an appreciable distance after it is released, before moving the contact members. Thus, the contacts are made and broken at a high velocity with a wiping action.

In practicing this invention in its broader aspects, it will occur to those skilled in the art that such relationship between the operating member and the movable contact carrying member or the contact carrying member and the contact members may take various forms and that the principles about to be disclosed are equally applicable to these forms.

Further objects and advantages of this invention will become apparent and this invention will be better understood from the following description referring to the accompanying drawings in which:

Fig. 1 is a side view, partially broken away, of a particular snap switch illustrating this invention;

Fig. 2 is a top view of the same switch;

Fig. 3 is a side view of the switch shown in Fig. 1 with the springs energized by movement of the operating shaft to the left;

Fig. 4- is a side view of the snap switch shown in Fig. l but illustrating the snap switch thrown in another position;

Fig. 5 is a side view of the switch shown in Fig. 4 with the springs energized by movement of the operating shaft to the right;

Fig. 6 is a sectional view taken along the line 66 of Fig. 5 showing the latch mechanism.

Referring to the drawings, we have shown therein a preferred embodiment of our double throw switch having a base 1 provided with upwardly extending

parallel portions

2 and 3 which pivotally support between them the movable contact carrying member 4 by means of a pivot or rivet 5. The

contact members

6 and 7 are pivotally connected each at one end to the movable member 4 by means of

pins

8 and 9, springs 10 and 11,

washers

12 and 13 and cotter pins Hand 15.

Members

6 and 7 are made of conductive material such as copper and have secured thereto on their outer ends pairs of laterally spaced contacts 6a and 7a which are conductive and made of a suitable contact making and breaking alloy. For example, a satisfactory contact can be made of an alloy having a high silver content.

The pivoted member 4 has an upwardly extending central portion 16 provided with an enlarged hole 17 which cooperates with a pin or rivet 18 extending therethrough and secured to the upper ends of the

portions

2 and 3, thereby to determine the range of pivotal movement of the member 4. A pin 19 is positioned in the portion 16 and operably connected to the operating member, shown as a rod or plunger 20, by means of the

springs

21 and 22 and a pin 28.

Frame members

23 and 23a and bearing or guide

members

24 and 24a aresecurcd to the base member 1. These

members

23, 23a, 24 and 24a and member 4 are preferably made of insulation such as Textolite laminated material. The plunger 20 is slidably mounted in the

members

24 and 24a. A pair of stationary contacts 25 are mounted on the member 23, and pairs of

stationary contacts

33 and 34 are mounted in the member 23a. A member 26 is secured to the plunger 20 by means such as a rivet 27. This member 26 has a slot in its lower side for the engagement of the pin 28, which operatively supports

springs

21 and 22.

A member 29 is shown attached to the lower side of the movable member 4 and has a U-shaped extension 39 on one end. Latching means shown as bar shaped member 31 is secured to the member 26 on the plunger 2% and has a lateral extension 32 (Fig. 6) on its projecting end that cooperates with this U-shaped extension 3% This extension 32 as viewed in Fig. 6 extends upward and is formed as shown by cutting away a portion of the upper side of the bar 31, leaving a notch 33a.

In operation, referring to Fig. 1, the plunger 2%) is moved toward the left, and as shown in Fig. 3 the

springs

21 and 22 have been carried over dead center, i. e., to the left side of the pivot 5, thus extering a force on pin 1? to move it toward the left about its pivot 5. However, the extension 32 of the member 31 still lies within and is engaged by the lower part of the U-shaped portion 30 of the latch member 29 whereby the member 4 is secured. It is obvious from Fig. 3 that the movable member 4 will be prevented from responding to the spring bias until the extension 32 has been moved toward the left a sufii- .cient distance to disengage the U-shaped portion 30 which and 33 respectively, the contact member 7 engaging the fixed contacts 34, as shown in Fig. 4.

Similarly, referring to Fig. 4, when the plunger 20- is moved toward the right, which return movement is effected by the spring 34a, the

springs

21 and 22 are carried over dead center, i. e., to the right-hand side of the pin 5, as shown in Fig. 5. Thus, a force is exerted on the pin 19 to move it toward the right and pivot the support member 4 clockwise. However, the U-shaped extension 36 is prevented from moving downward by the extension 32 of member 31, which extension 32 has moved under the extension 30, and the support member 4 will be prevented thereby from responding to the spring bias until the extension 32 has moved toward the right past the U-shaped extension 30 whereupon the extension 39 is free to move downward to provide for pivotal movement of the member 4. After the latch member 31 has thus moved sufficiently to free the extension 30 of member 29, the stressed

springs

21 and 22 will cause the movable member 4 to rotate clockwise about the pin 5 and pick up members 6 and '7 to the positions shown in Fig. 1.

With the structure disclosed for mounting the contact member '7 on the pin 8 so as to pivot on the member 4, it is easily seen (Fig. 1) that movable member 4 will rotate counterclockwise approximately 20 degrees before contact member 7 is returned by the spring 10 to a position flat against the member 4 and thereafter breaks contact with the pair of fixed contacts 33. It should also be noted that this pivotal movement of the member 4 causes a wiping action between the contact surfaces during the instant between the release of the latch and the breaking of contact. As the movable member 4 is allowed to move approximately 20 degrees before causing the contact member 7 to leave the contacts 33, the movable contact carrier 4 during that period accelerates to a high speed so that the contact member 7 will leave the fixed contacts 33 with a much higher velocity than would be possible if the contact member 7 were rigidly attached to the member Thus, it is easily seen that we have developed a switch mechanism that will cause a high velocity break of the contact between the member 7 and the contacts 33. A similar high velocity break is developed between the member 6 and the contacts 25, and the member 7 and the contacts 34.

In the particular switch shown the contact member 7 is of some material such as copper which is a good conductor of electrical current. Thus, the contacts 33 are electrically shorted when the member 7 is in contact with them. When the contact member 7 is caused to break contact with fixed contacts 33, it is clear from the drawing that two air gaps will result. It is possible with the switch we have shown to have four air gaps in the circuit controlled, by serially connecting the pairs of

fixed contacts

25 and 33. It is also possible to have a fourth set of fixed contacts placed on the upper portion of frame member 23, in a location similar to that of contacts 33 on frame member 23a.

The hole 17 through which the rivet 18 is passed is of sufiicient diameter to allow rotation of the movable memher 4 enough to cause the contact member 7 to be displaced relative to the pin 8 when contact is made, whereby the spring it) is caused to be partially compressed as shown in Fig. 1. However, the inertia of the member 4 and pressure of the

springs

21 and 22 are not transmitted directly to the contact surfaces of the fixed contacts when contact is made or during contact. The only force transmitted to the contacts when the switch is operated is caused by the inertia of the contact member 6 or 7and the partial compression of spring 10.

The cut-away section of the frame member 23 in Fig.

1 shows that the contact member 6 is allowed to pass through the hole 35 in the frame member 23 without restriction. Thus wear of the contacts 25 and contact memher 6 will not cause a poor connection to be made by the switch mechanism. A similar hole is located in frame member 23a to allow the unrestricted movement of the contact member 7. I

The head of the pin 3 as shown in the cut away portion 3 of Fig. l is protected by an insulating shield 36. A similar shield is placed on the head of the pin 9. Thus, it is easily seen that there is no electrical connection between the

pins

8 or 9 and the

latch mechanism

29 and 31, which may be electrically connected to the plunger 20 through the member 26.

It will thus be seen that this invention provides an improved latch mechanism wherein the contact carrying member is prevented from movement before the springs causing its movement are well past dead center and where the force of the springs biasing the member toward movement is much greater than that of the ordinary toggle switch. The added feature of having the contact member pivotally mounted on the contact support member allows these contact members to be picked up after the contact support member has gained sufficient momentum to cause an instantaneous snap action at the point of contact. Also this improved mounting of the contactors on the carrying member allows the contact members to make high velocity connections without damage to the contact surfaces which otherwise might be caused by the inertia of the movable member and the pressure of the springs.

While we have shown and described the particular embodiment of this invention, further modifications and improvements will occur to those skilled in the art. We desire it to be understood, therefore, that this invention is not limited to the form shown and we intend the appended claims to cover all modifications which do not depart from spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A snap switch mechanism comprising an operating plunger, a plurality of spring members energized by said operating plunger, movable support means connected to said spring members for actuation thereby, contact means attached to said support means, a U-shaped extension attached to said support means, and a latching means attached to said operating plunger and operable in conjunction with said U-shaped extension to prevent the actuation of said support means until said plunger has been moved a predetermined distance whereby a more positive snap action is obtained.

2. A snap switch comprising stationary contacts, movable contact members, an operating plunger, a plurality of spring members energized by said operating shaft, a movable member supporting said movable contact member and connected to said spring members for actuation thereby, a U-shaped extension attached to said movable member, a latching means connected to said operating plunger and operable thereby to engage said U-shaped extension to prevent actuation of said movable member until said plunger has been moved a predetermined distance whereby a more positive snap action is obtained.

3. A snap switch comprising a stationary contact, an operating plunger, spring members energized by said operating plunger, a movable support member connected to said spring members for actuation thereby, a movable contactor being pivotally mounted on said support member, a U-shaped extension attached to said support member and a latch member connected to said operating plunger and operable thereby to engage said U-shaped extension to prevent actuation of said support member until said operating plunger has been moved a predetermined distance whereby said spring members are moved to provide a more positive snap action.

tially compressed spring thereon whereby said movable contact member is biased to move with movement of said support member, a U-shaped extension attached to said support member, and a latch member attached to said operating plunger and operable thereby to engage said U-shaped extension to prevent actuation of said support member until said operating plunger has been moved a predetermined distance whereby said spring members are moved to provide a more positive snap action.

5. A snap switch comprising a base member, stationary contacts attached to said base member, bearing members attached to said base member, an operating plunger journalled in said bearing members, spring members moved by said operating plunger, a movable support member pivotally attached to said base member and connected to said spring members for actuation thereby, a movable contact member pivotally mounted on said support member, means for limiting the movement of said support member to provide for pivoting said movable contact member on said support member during contact with said stationary contacts, a U-shaped extension attached to said support member, and a latch member attached to said operating shaft and operable thereby to engage said U-shaped extension to prevent actuation of said support member by said spring members until said operating plunger has been moved a predetermined distance whereby said spring members are moved to provide a more positive snap action.

6. A snap switch comprising a base member, stationary contacts attached to said base member, bearing members attached to said base member, an operating plunger journalled in said bearing members and axially movable therein, spring members moved by said operating plunger, a movable support member pivotally attached to said base member and connected to said spring members for actuation thereby, a movable contact member pivotally mounted on said support member, means for limiting the movement of said support member, said means being such that said movable contact member is pivoted on said support member on the order of 20 degrees when in contact with said fixed contacts, a U-shaped extension attached to said support member, and a latch member attached to said operating plunger and operable thereby to engage said U-shaped extension to prevent actuation of said support member until said operating plunger has been moved a predetermined distance.

7. In a double throw switch mechanism, an operating plunger, a movable support means, first contact means mounted on said support means, a pair of stationary contact means adapted to be alternately engaged by said first contact means, a resilient member operatively connected to said support means and operably connected to said plunger, an extension rigidly attached to said support means, and a latching means secured parallel to said plunger for engaging said extension to prevent the operation of said support means by said resilient member in either direction until said plunger has moved said latch a predetermined distance.

8. In a double throw switch mechanism, an operating plunger, a rotatable support means, first contact means pivotably mounted on said support means, said first contact extending outward from the center of rotation of said support means to promote a contact surface moving a greater tangential distance than the mounting point, a pair of stationary contacts adapted to be alternately engaged by said first contact means, said pair being positioned to inhibit extreme tangential movement of said first contact whereby a wiping contact is made, a resilient member operatively connected to said support means and operably connected to said plunger, an extension rigidly attached parallel to and a predetermined distance from said support means, and a latching means secured parallel to said plunger for engaging said extension on a side adjacent to said support means and on a side remote from said support means to prevent the operation of said support means by said resilient member in either direc tion until said plunger has moved said latch a predetermined distance.

References Cited in the file of this patent UNITED STATES PATENTS 1,031,611 Anderson July 2, 1912 1,349,851 Parsons Aug. 17, 1920 1,802,178 Leonard Apr. 21, 1931 1,864,369 Pepper June 21, 1932 FOREIGN PATENTS 661,914 Germany June 30, 1938