Higher rated double-pole trigger switch

A multipurpose electric trigger switch adapted to be mounted in the handle of a portable electric tool for controlling the A. C. power circuit and, to afford a higher rating, the switch is provided with double-pole butt contacts. A movable contactor is pivoted and translated on a resilient terminal into wiping and abutting contact with a stationary terminal in response to linear sliding movement of an operator having a cam which engages inclined camming surfaces on the contactor.

BACKGROUND OF THE INVENTION 
Electric switches, including 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 subject to excessive wear that 
limits the life of the switch, contacts that are teasible 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 and the like. While my prior U.S. Pat. No. 
3,869,590, issued Mar. 4, 1975 and my pending application Ser. No. 
586,059, filed June 11, 1975, disclose switch structures that overcome 
these disadvantages, this invention relates to an alternative structure 
for accomplishing the same. 
SUMMARY OF THE INVENTION 
This invention relates to electric switches, including double-pole higher 
rated tool handle switches of the trigger operated type. 
An object of the invention is to provide an improved switch. 
Another 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 which will positively shear and break any contact welds. 
Another specific object of the invention is to provide an improved switch 
of the aforementioned type having non-teasible contacts. 
Another specific object of the invention is to provide an improved switch 
of the aforementioned type 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 "off" and trip "on" positions to prevent repeated or accidental 
switch operation. 
Another specific object of the invention is to provide an economical and 
reliable higher rating contact mechanism for an electric switch. 
Other objects and advantages of the invention will hereinafter appear.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, 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, 125 volts, 
having an inrush current of 60 amperes on make and current of 12 amperes 
on break, for example, it will have an operational life rating of 50,000 
to 60,000 operations, an increase of 4 to 5 times over prior lower rated 
switches in the same size of housing. 
As shown in FIGS. 1 and 3, the 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 in FIG. 1. 
The top of this base is partly closed by an insulating cover 4, as shown 
in FIG. 1. As shown in FIG. 2, this cover is provided with a slot 4b 
rearwardly opening into a wider slot 4a, the purpose of which is described 
more fully hereinafter. This cover is also provided with elongated narrow 
locating ears 4c and 4d protruding from the sides thereof to seat the 
cover in complementally formed notches in the base 2, as shown in FIGS. 2 
and 4. The interior of the base is divided into two compartments, left and 
right, for the respective poles of the double-pole switch, by a 
longitudinal center dividing wall 2a, FIG. 4, that extends all the way up 
to cover 4. These left and right compartments are each divided into two 
subcompartments, front and back, for the movable and stationary contact 
connector clips, by a lateral wall 2b, FIG. 1, extending across the middle 
thereof. Each back subcompartment is provided with a stop or boss 5 and 7 
extending laterally from center dividing wall 2a of the base to limit the 
clockwise pivoting of movable contactors 26 and 27, as will be more fully 
described hereinafter. 
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 a known manner. A 
trigger return spring provides the switch with momentary action. For this 
purpose, a helical compression spring 10 is positioned in a groove 6c that 
extends forwardly partway from the rear end of slidable portion 6b of the 
trigger. The front end of this spring bears against the vertical wall at 
the front end of such groove and the rear end of this spring bears against 
the rear vertical wall of the frame. To limit trigger movement in both 
directions, the frame is provided with a pair of rectangular apertures 8a 
and 8b and the top of the slidable portion of the trigger is provided with 
a pair of projections 6d and 6f extending up through the respective 
apertures for limited movement therein as shown in FIGS. 1 and 4. 
Left and right stationary contact terminals 12 and 13 are retained in slots 
in the rear end of base 2, FIGS. 1 and 3. These rigid terminals extend 
from their anchored ends up, then down and toward the front, and then down 
and slightly toward the rear, as shown in FIG. 1. A stationary contact 14 
is affixed to terminal 12 and another stationary contact (not shown) is 
affixed to terminal 13. Left and right flexible cantilever terminals 15 
and 16 are retained in slots in the front end of base 2, FIGS. 1 and 3. 
These flexible terminals extend from their anchored ends up then toward 
the rear, reduced rear end portions 14a and 16a, FIGS. 1, 3 and 4, passing 
through rectangular apertures in the shank portions of the respective 
contactors 26 and 27 to bias the contactors upwardly, as will be more 
fully described hereinafter. 
In order to make electrical connections to the two pairs of terminals of 
the double-pole switch, there are provided a first pair of connector clips 
17 and 18 at the rear bottom of the base, and a second pair of connector 
clips 19 and 20 at the forward bottom of the base, as shown in FIGS. 1 and 
5. These clips are formed alike from a ribbon-like metal strip and each is 
provided with a pair of short wings at the vertical mounted end thereof 
adjacent lateral wall 2b of the base whereby they are retained in a pair 
of vertical grooves 2c in the wall as shown in FIG. 5. From the lower end 
of such vertical retaining portion, each connector clip is bent up about 
30.degree. from the horizontal so that the other end thereof rests against 
the flat inner surface of the retaining portion of the respective 
terminal. The bottom of the base is provided with two pairs of holes 21, 
22 and 23, 24, FIGS. 1 and 3, through which solid or tinned, stranded 
electric wires may be pushed in between the terminals and the respective 
connector clips to make connections thereto. 
Each flexible terminal 15 and 16 carries a movable contactor 26 and 27 
respectively. Contactor 26 has: an upper, molded insulating portion 26a 
having two oppositely inclined camming surfaces meeting at an apex; an 
enlarged middle, insulating portion 26b having trunnions 26d and 26e 
formed on the lateral ends thereof; and a depending electrically 
conductive shank portion 26c having a terminal-receiving rectangular 
aperture 26f and a contact 28 attached to one surface of its lower end. 
Contactor 27 is identically formed and has a contact 29 mounted thereon. 
As aforedescribed, and shown in FIGS. 1, 3 and 4, the reduced end portion 
15a of flexible terminal 15 extends through aperture 26f, in electrical 
connection with shank portion 26c and biases the contactor upwardly. 
Trunnions 26d and 26e ride up and down in slots 30 and 31, FIGS. 1 and 4, 
formed in the base side wall and center dividing wall, thereby permitting 
pivoting of the contactor together with vertical reciprocal motion 
thereof. Likewise, contactor 27 pivots and reciprocates vertically in the 
right compartment of the base. 
As seen in FIG. 1, the trigger is formed with recess 6e for slidably 
receiving a single cam insert 32. This insert extends across the width of 
frame 8, as shown in FIG. 4, and has a rear portion 32a extending 
rearwardly beyond the recess and a lower rear portion 32b extending 
downwardly therefrom through slot 4a in the cover, FIGS. 1 and 2. Portion 
32b is spaced slightly above center dividing wall 2a. A lower front 
portion 32c, FIGS. 1 and 2, extends downwardly from the center of the 
insert through slot 4b. The front edge of slot 4b and the rear wall of 
base 2 act as stops for the forward-rearward sliding of the insert. The 
insert is further provided with a camming tip 32d formed on its bottom 
surface by a pair of spaced lateral grooves for engaging the inclined 
camming surfaces of both contactors 26 and 27. 
Operation of the switch will now be described. FIG. 1 depicts full trigger 
release with projections 6d, 6f stopped against the front edge of 
apertures 8a, 8b and with lower portion 32c stopped against the front edge 
of slot 4b. Upon depression of the trigger, against the bias of spring 10, 
the insert will remain stationary until the front vertical wall of recess 
6e strikes the front of insert 32, thus resulting in lost motion of the 
trigger to thereby increase trigger movement between trip "off" and trip 
"on" positions. Further depression of the trigger will carry the insert 
with it to cause downward camming of the contactors. When camming tip 32d 
crosses the apex formed by the two inclined camming surfaces of contactor 
26, the contactor will suddenly pivot counterclockwise about trunnions 26d 
and 26e to close contacts 28 and 14. Contactor 27 likewise pivots to close 
the contacts in the right compartment. The insert snaps rearwardly, 
allowing upward movement of the contactor which causes wiping action of 
the contacts as they engage. Upon trigger release, the insert remains 
stationary and stopped against the rear wall of base 2 until the rear wall 
of recess 6e strikes the upper rear part of the insert. Further release of 
the trigger carries the insert forwardly with it to cause downward 
movement of the contactor which shears and breaks any welds between the 
contacts as they disengage when the tip 32d passes over the apex. 
It is important to provide a forward stop for insert 32 so that camming tip 
32d can provide an upward stop for the contactors under the bias of the 
flexible terminals, thus effecting a clockwise torque on the contactors 
against stops 5 and 7 respectively. After the camming tip passes the apex, 
the upward bias of the flexible terminal produces a counterclockwise 
torque on the contactor because the upward stop (camming tip 32d) is now 
on the negatively sloped rear camming surface and because the contactor 
cannot move horizontally. 
It is also important to provide a rearward stop for insert 32 so that 
camming tip 32d can remain an upward stop for the contactor when the 
trigger is fully depressed and the contacts are closed. These stops and 
the horizontal constrainment provided by slots 30 and 31 in the walls of 
the base enable the upward bias of the flexible terminal to produce the 
requisitely directed torque to pivot the contactor. 
While a trigger switch has been shown, it can easily be appreciated the 
mechanism disclosed hereby is adaptable for use in other types of 
switches. For example, sliding portion 6b may be horizontally reciprocated 
by a toggle lever cooperating therewith from above. 
The objects of the invention are achieved in the following respects: 
there is positive shearing and breaking of any welds because of the 
pivoting and vertically downward motion of the contactor during trigger 
release; 
the contacts are non-teasible because the camming tip cannot be held on the 
apex of the contactor; 
the amount of wipe is controlled by the flexure of the flexible terminal, 
the slope of the inclined camming surfaces of the contactor, and the 
vertical depth of the camming tip; 
there is low contact bounce because of the continuous counterclockwise 
torque applied to the contactor by the upward bias of the flexible 
terminal after the camming tip crosses the apex; 
there is maximum contact pressure at the point of trip open because the 
contactor is cammed to its extreme downward position against the bias of 
the flexible terminal at such point; 
there is substantial trigger movement between trip "on" and trip "off" 
positions due to the lost motion of the camming insert within recess 6e 
and the distance across an inclined surface which the camming tip must 
traverse before reaching the apex.