US3869590A

US3869590A - Double-pole tool handle switch

Info

Publication number: US3869590A
Application number: US447031A
Authority: US
Inventors: Harold W Hults
Original assignee: CUTTER HAMMER IN
Current assignee: CUTTER HAMMER IN; CUTTER-HAMMER IN
Priority date: 1974-02-28
Filing date: 1974-02-28
Publication date: 1975-03-04
Anticipated expiration: 1992-03-04
Also published as: GB1464668A

Abstract

A trigger switch adapted to be mounted in the handle of a portable electric tool for controlling the A.C. power circuit. To afford a higher rating, the switch is provided with double-pole butt contacts that have a controllable amount of wipe, very low bounce, are non-teasable, have maximum contact pressure at the point of tripping open, and have a considerable amount of trigger movement between trip ''''on'''' and trip ''''off'''' positions. This is obtained by providing a movable contact carrier block having a pair of U-shaped movable contacts embracing its ends and an overcenter cam on top engaged by a spring-biased plunger extending down from a hole in a horizontally slidable trigger. This contact carrier block is biased up by a pair of resilient cantilever terminals continuously in electrical contact with the U-shaped movable contacts that slide thereon so that the relative bias between the plunger springs and the resilient cantilever terminals determines the amount of wipe in a vertical plane between forward ends of the U-shaped movable contacts and respective vertically-arranged stationary contacts.

Description

United States Patent 1 Hults Mar. 4, 1975 DOUBLE-POLE TOOL HANDLE SWITCH [75] Inventor: Harold W. Hults, New Berlin, Wis.

[73] Assignee: Cutler-Hammer, Inc., Milwaukee,

Wis.

[22] Filed: Feb. 28, 1974 [2]] Appl. No.: 447,031

[52] US. Cl. 200/157, 200/77 [51] Int. Cl. H0lh 9/06, HOlh 5/10 [58] Field of Search 200/157, 153 LA, 77;

[56] References Cited UNITED STATES PATENTS 6/1965 Pierce 200/77 .115 11/1965 Feher, Jr 200/77 6/1973 Sahrbacker et al 200/l57 11/1973 Brown 200/157 Prinmry Erantiner-James R. Scott Assistant Eruminer-William .1. Smith Attorney, Agent, or Firm-H. R. Rather; Wm. A. Autio [57] ABSTRACT A trigger switch adapted to be mounted in the handle of a portable electric tool for controlling the A.C. power circuit. To afford a higher rating. the switch is provided with double-pole butt contacts that have a controllable amount of wipe, very low bounce, are non-teasable, have maximum contact pressure at the point of tripping open, and have a considerable amount of trigger movement between trip on and trip *off" positions. This is obtained by providing a movable contact carrier block having a pair of U- shaped movable contacts embracing its ends and an over-center cam on top engaged by a spring-biased plunger extending down from a hole in a horizontally slidable trigger. This contact carrier block is biased up by a pair of resilient cantilever terminals continuously in electrical contact with the U-shaped movable contacts that slide thereon so that the relative bias between the plunger springs and the resilient cantilever terminals determines the amount of wipe in a vertical plane between forward ends of the U-shaped movable contacts and respective vertically-arranged stationary contacts.

9 Claims, 5 Drawing Figures PATENTED H975 3 869 590 saw 1 of 2 ZOE PATENTEDHAR 4% 3,869,590

sum 2 9 2 ll we I l l J L 1 L'Z6L 26K DOUBLE-POLE TOOL HANDLE SWITCH BACKGROUND OF THE INVENTION Trigger switches for portable electric tools have been known heretofore. However, these prior switches have been subject to one or more disadvantages that have limited their electrical capabilities such as sliding contacts that wear and limit the life of the switch, contacts that are teasable and contact operating mechanisms that reduce contact pressures prior to opening thereby causing early deterioration, and short trigger movement between contact closed and open positions that causes frequent or false operation and might create dangerous conditions particularly when used in portable electric circular saws. While these prior trigger switches have been useful for their intended purpose, this invention relates to improvements thereover.

SUMMARY OF THE INVENTION This invention relates to double-pole higher rated tool handle switches and more particularly to such switches of the trigger actuated type.

An object of the invention is to provide an improved higher rated switch.

A more specific object of the invention is to provide an improved butt contact switch having a controllable amount of wipe.

Another specific object of the invention is to provide an improved switch of the aforementioned type having low contact bounce.

Another specific object of the invention is to provide an improved switch of the aforementioned type having maximum contact pressure at the point of trip open.

Another specific object of the invention is to provide an improved switch of the aforementioned type having substantial trigger movement between trip on and trip of positions to prevent repeated or accidental switch operation.

Another specific object of the invention is to provide an improved non-teasable switch.

Another specific object of the invention is to provide an economical and reliable higher rating contact mechanism for a tool handle switch.

Other objects and advantages of the invention will hereinafter appear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged partial, vertical cross-sectional view taken along line 11 of FIG. 4 to show one pole of the two-pole tool handle switch;

FIG. 2 is a horizontal cross-sectional view like FIG. 3 but with the contact actuator block removed to show a top view of the cantilever terminals;

FIG. 3 is a horizontal cross-sectional view taken along line 3-3 of FIG. 1 to show a top view of the double-pole contacts;

FIG. 4 is a vertical cross-sectional view taken along line 4-4 of FIG. 1 to show a rear view of the actuator block; and

FIG. 5 is a fragmentary horizontal cross-sectional view taken along line 5-5 of FIG. 1 to show the mounted ends of the wire retention clips and the mounting slots in the base therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1-5, there is shown a double-pole higher rated tool handle switch constructed in accordance with the invention. By higher rated is meant that for an electrical rating of 12 amperes, volts, having an inrush current of 60 amperes on make and a current of 12 amperes on break, for example, it will have an operational like rating of 50,000 to 60,000 operations, an increase of four to five times over prior switches, in the same size of housing. Thus, it can be directly substituted for the lower rated switches without any modification of the nesting structure within the tool handle.

As shown in FIGS. l-3, this switch, is provided with an insulating base 2 generally rectangular in shape and open at the top for housing the double-pole switch contacts, the left pole of which is shown exposed in FIG. 1. The top of this base is closed by an insulating cover 4 having an aperture 4a therein providing clearance for the switch actuating plunger hereinafter described. An insulating trigger 6 has a finger-engaging portion 6a extending forwardly from the base and a slidable portion 6b overlying the base and held thereon by a frame 8 that is secured to the base in known manner.

A trigger return spring provides the switch with a momentary action. For this purpose, a helical compression spring 10 is positioned in a groove 60 that extends forwardly from the rear end of slidable portion 6b of the trigger. The rear end of this spring bears against the inner rear wall of the frame and the front end thereof bears against the wall at the front end of such groove. To limit trigger movement in both directions, the frame is provided with a pair of rectangular apertures 8a and the top of the slidable portion of the trigger is provided with a pair of projections 6d extending up through the respective apertures for limited movement therein as shown in FIGS. 1 and 4.

To lock the trigger in its depressed position wherein the contacts are closed, a bushing 8b is secured to. the upper left forward part of the frame as shown in FIG. 4. This bushing retains a spring-biased lock pin 8c whose inner end is shaped to hook onto an undercut shoulder 6e on the left side of the slidable portion of the trigger as shown in FIGS. 1 and 4. Thus, when the trigger is depressed and then the lock pin is depressed and the trigger released enough to effect engagement of the lock pin on shoulder 6e, the switch becomes locked in its on or contacts-closed position. A slight depression of the trigger thereafter releases the lock to allow the trigger to return to its of position.

A switch actuating plunger 12 extends down from the trigger through aperture 4a in the cover into the base. For this purpose, a round bore 6f extends up from the bottom of the slidable portion of the trigger large enough to freely receive plunger 12. The plunger is provided with a downwardly extending bore 12a to receive a helical compression spring 14. As shown in FIG. 1, this spring is between the upper end of bore 6f within the trigger and the lower end of bore 12a within the plunger to bias the plunger downwardly against the camming surface 16a of a movable contact actuator block 16 hereinafter described.

This actuator block 16 carries left and right

movable contacts

18L and 18R, respectively, one at each end thereof. Each movable contact is U-shaped to embrace the associated end of the actuator block as shown in FIGS. 1 and 3 and the block is guided at its ends by the left and right inner walls of the base. To retain the movable contacts in place, the actuator block is provided with'a pair of short projections 16b at its bottom near its ends fitting into respective holes in the movable contacts as shown in FIG. 3.

As shown in, FIGS. 1 and 3, camming surface 16a on the actuator block islocated at the center between the movable contacts and is inverted V-shaped so that when, the plunger is moved in one direction up one incline over-center across thehigh point onthe cam, the spring bias causes the actuator block to be moved with snap-action in the other direction while the plunger slidesdownthe other slope of the cam surface.

The movablecontact actuator block is provided with aresilient upward bias to balance the downward bias thereon provided by plunger spring 14. For thispurpose, this actuator block and the movable contacts carried thereby are supported by a pair of cantilever, flexible terminals including a left terminal 20L and a right terminal 20R along which the respective movable contacts slide. As shown in FIG. 1, the movable contacts and their actuator block rest on the horizontal cantilever portions of the flexible terminals. These terminals are bent so that they extend to the right and up and then in a loop down into mounting slots in the rear end of the base where they are retained. The forward, cantilever portions of these flexible terminals bias the movable contacts and actuator block up against the plunger. The relative bias between these flexible terminals and the plunger spring is selected to afford the desired small amount of wiping action between the movable and stationary contacts.

The left andright stationary contacts 22L and 22R are retained in similar slots in the forward end .of the base. These stationary contacts extend from their anchored ends up, then toward the rear and then down partway to form vertical contacting portions against which the vertical front portions of the U-shaped movable contacts bear when the contacts are closed. These stationary contacts are alike and each is provided with a pair of short wings on the edges of its contacting portion, one of which wings is retained in a vertical groove 2a in the center-dividing wall 2b of the base to fix the stationary contact securely therein as shown in FIGS. 2 and3.

lnforder to makeelectrical connections to the two stationary contacts and the two flexible terminals of the double-pole switch, there are provided a first pair of wire clamps, left wire clamp 24L and right wire clamp 24R at theforward bottom of the base, and a second pair of wire clamps, left wire clamp 26L and right wire clamp 26R, at the rear bottom of the base as shown in FIGS. 1'and 5. These wire clamps are formed alike from a ribbon-like metal strip and are each provided with a pair of short wings at the vertical mounted end thereof whereby they are retained in pair of vertical grooves 2c in the base as shown in FIG. 5. From the bottom of such. vertical retaining portion, each wire clamp is bent up about 30from the horizontal so that the other end thereof rests against the flat inner surface of the retaining shank of the respective stationary contact or flexible terminal. The bottom of the base is provided with two pairs of holes, 28L, 28R, and 30L, 30R as shown in FIGS. 1 and 2 through which solid or tinned, stranded electric wires may be pushed in between the terminals and the wire clamps to make connections thereto.-

As shown in FIG. 1, when the trigger is depressed, the lower end of plunger 12, which has an angular surface matchingthe cam surface 16a, slides up the front incline of the camming surface on the actuator block. During this action, there is some compression of the plunger spring and some downward movement of the actuator block against the force of the .flexible terminals. At this time, the actuator block is stopped against the center dividing wall 2b of the base. This center dividing wall has a slot 2d wide enough to allow reciprocal movement of the actuator block. The two compartments on opposite sides of this wall accommodate the two poles of the double-pole switch. When the plunger passes over the high point of -thec'am, the resilient bias causes the actuator block to snap forward to close the contacts; During this motion, the movable contacts slide on the horizontal cantilever portions of the flexible terminals and remain constantly in electrical contact therewith. Also, the plunger slides partway down the rear slope of the actuator block camming surface and it is the forward component of the force or bias effected by the plunger against this slope and upward bias of the flexible terminals that snaps the actuator block forward. As a result, the forward ends of the movable contacts close onto the respective stationary contacts.

Further depression of the trigger toward the end of its stroke causes the plunger to move further down the rear slope and allows the upward bias of the flexible terminals to move the actuator block up thereby causing a small amount of wiping of the movable contacts on the stationary contacts to effect cleaning of the contacts.

When the trigger is released, a wiping action is effected before the contacts open. Spring 10 the trigger to its normal extended position shown in FIG. 1. At the start of this motion, the plunger slides up the rear incline of the actuator block. This'causes the bias provided by the plunger spring to move the actuator block a small amount downwards against the upward bias of the flexible terminals. In this motion, the actuator block carries the movable contacts with itso that they slide a small amount on the stationary contacts for limited wiping to effect cleaning of the contacts.

Since these are butt contacts having a small amount of wiping action, the wiping action is selected small enough to clean the contacts but not so much as to cause excessive wear as is the case with sliding contacts. This desired amount of sliding or wiping of the contactsis determined by the relative bias in the plunger spring and the flexible terminals.

When the plunger reaches the high point of the camming surface as it slides up the rear incline, maximum force is applied by the movable contacts against the stationary contacts. An instant later, the plunger passes over this high point and the contacts are snapped open. Thus, maximum contact force occurs just before opening so that there can be no teasing of the contacts which would result in burning and deterioration. Also, this relative bias cam action contact structure has very low bounce on closing thereby reducing arcing to a minimum. Arcing, of course, is another cause of contact deterioration and it is desirable to reduce the bounce to increase contact life. Also, due to the lengths of the inclines and the distance that the actuator block moves to close the contacts, the trigger must be moved substantially between trip on and trip off points to prevent repeated or accidental switch operation which might occur were there a very short trigger stroke.

While the apparatus hereinbefore described is effectively adapted to fulfill the objects stated, it is to be understood that this invention is not intended to be limited to the particular preferred embodiment of doublepole higher rated tool handle switch disclosed, inasmuch as it is susceptible of various modifications without departing from the scope of the appended claims.

I claim:

1. A double-pole tool handle switch comprising:

an insulating housing;

a return spring biased switch actuator mounted for sliding movement on said housing;

a plunger extending from said switch actuator;

a spring biasing said plunger and said plunger being resiliently depressible against the force of said bias spring;

a movable contact actuator block having a doubleincline camming surface comprising opposite inclines meeting at a high point arranged for engagement by said plunger;

double-pole butt contacts comprising a pair of stationary contacts mounted in said housing and a pair of movable contacts carried by said actuator block for engaging the respective stationary contacts, and the contacting portions of said stationary and movable contacts being generally parallel to the axis of said plunger, said stationary contacts having terminals adapted for connection to an external circuit;

and connector means comprising a pair of connector terminals and means mounting them in said housing and adapted to be connected to an external circuit and having biasing portions remaining in contact with the respective movable contacts throughout the movement of said actuator block and applying a counter bias to said actuator block to balance the bias of said plunger spring;

and actuation of said switch actuator causing said plunger to slide up the front incline of said camming surface and, after passing over said high point, to cause snap-action movement of said actuator block while said biased plunger acts on said rear incline and said movable contacts remain in sliding contact with said biasing portions of said connector terminals thereby to cause said movable contacts to close with the respective stationary contacts with minimum bounce;

and further actuation of said switch actuator causes said plunger to move further down the rear incline to allow said counter bias to afford controlled wiping between said movable and stationary contacts;

and release of said switch actuator to return under force of its return spring causing said plunger to slide up the rear incline of said camming surface and at the same time to cause movement of said actuator block against said counter bias to afford controlled wiping between said movable and stationary contacts and, upon reaching said high point at maximum contact pressure, causing said contacts to trip open with snap-action as said biased plunger acts on the front incline of said camming surface thereby to prevent teasing of said contacts.

2. The invention defined in claim 1, wherein:

said switch actuator is mounted for linear sliding movement;

and said plunger is recessed in said switch actuator to extend perpendicular to the line of said linear movement.

3. The invention defined in claim 1, wherein:

said movable contacts are U-shaped and embrace the opposite end portions of said actuator block on opposite sides of said double-incline camming surface.

4. The invention defined in claim 3, wherein:

each stationary contact is generally inverted .l-shaped wherein the longer stem forms a connector and the outside surface of the shorter stem forms a contacting portion for engagement by the front end of the respective U-shaped movable contact.

5. The invention defined in claim 1, wherein:

said biasing portion of each connector terminal comprises a flexible cantilever end portion extending beneath the respective movable contact and biasing the latter and said actuator block against said plunger.

6. The invention defined in claim 5, wherein:

said means mounting said connector terminals in said housing comprises slots in the housing wherein the other end portions of said connector terminals are retained.

7. The invention defined in claim 6, wherein said connector means comprises:

a pair of wire clamps, each formed of a ribbon-like member having a pair of wings at one end portion whereby it is retained in a vertical slot in the housing and being bent therebelow so that its other end extends at an angle up against the surface of said other end portion of said connector terminal so that a bare wire can be inserted therebetween.

8. The invention defined in claim 1, wherein:

said housing comprises a dividing wall forming two compartments for the respective poles of said double-pole switch;

and a slot in said dividing wall affording clearance for movement of said actuator block.

9. The invention defined in claim 1, wherein said housing comprises;

an insulating plate between said contacts and said switch actuator on which the latter slides.

Claims

1. A double-pole tool handle switch comprising: an insulating housing; a return spring biased switch actuator mounted for sliding movement on said housing; a plunger extending from sAid switch actuator; a spring biasing said plunger and said plunger being resiliently depressible against the force of said bias spring; a movable contact actuator block having a double-incline camming surface comprising opposite inclines meeting at a high point arranged for engagement by said plunger; double-pole butt contacts comprising a pair of stationary contacts mounted in said housing and a pair of movable contacts carried by said actuator block for engaging the respective stationary contacts, and the contacting portions of said stationary and movable contacts being generally parallel to the axis of said plunger, said stationary contacts having terminals adapted for connection to an external circuit; and connector means comprising a pair of connector terminals and means mounting them in said housing and adapted to be connected to an external circuit and having biasing portions remaining in contact with the respective movable contacts throughout the movement of said actuator block and applying a counter bias to said actuator block to balance the bias of said plunger spring; and actuation of said switch actuator causing said plunger to slide up the front incline of said camming surface and, after passing over said high point, to cause snap-action movement of said actuator block while said biased plunger acts on said rear incline and said movable contacts remain in sliding contact with said biasing portions of said connector terminals thereby to cause said movable contacts to close with the respective stationary contacts with minimum bounce; and further actuation of said switch actuator causes said plunger to move further down the rear incline to allow said counter bias to afford controlled wiping between said movable and stationary contacts; and release of said switch actuator to return under force of its return spring causing said plunger to slide up the rear incline of said camming surface and at the same time to cause movement of said actuator block against said counter bias to afford controlled wiping between said movable and stationary contacts and, upon reaching said high point at maximum contact pressure, causing said contacts to trip open with snap-action as said biased plunger acts on the front incline of said camming surface thereby to prevent teasing of said contacts.

2. The invention defined in claim 1, wherein: said switch actuator is mounted for linear sliding movement; and said plunger is recessed in said switch actuator to extend perpendicular to the line of said linear movement.

3. The invention defined in claim 1, wherein: said movable contacts are U-shaped and embrace the opposite end portions of said actuator block on opposite sides of said double-incline camming surface.

4. The invention defined in claim 3, wherein: each stationary contact is generally inverted J-shaped wherein the longer stem forms a connector and the outside surface of the shorter stem forms a contacting portion for engagement by the front end of the respective U-shaped movable contact.

5. The invention defined in claim 1, wherein: said biasing portion of each connector terminal comprises a flexible cantilever end portion extending beneath the respective movable contact and biasing the latter and said actuator block against said plunger.

6. The invention defined in claim 5, wherein: said means mounting said connector terminals in said housing comprises slots in the housing wherein the other end portions of said connector terminals are retained.

7. The invention defined in claim 6, wherein said connector means comprises: a pair of wire clamps, each formed of a ribbon-like member having a pair of wings at one end portion whereby it is retained in a vertical slot in the housing and being bent therebelow so that its other end extends at an angle up against the surface of said other end portion of said connector terminal so that a bare wire can be inserted therebetween.

8. The invention defined in claim 1, wherein: said housing comprises a dividing wall forming two compartments for the respective poles of said double-pole switch; and a slot in said dividing wall affording clearance for movement of said actuator block.

9. The invention defined in claim 1, wherein said housing comprises; an insulating plate between said contacts and said switch actuator on which the latter slides.