Power control for portable electric tool

Claim 2

In an electric switching and power control device for portable tools, a casing, a metal plate and an insulation plate within said casing in parallel spaced relation, a rotary member pivotally mounted between said plates, a rotary contact driven by said member, a resistance element engaged by said rotary contact to vary the effective amount of said resistance, an operating trigger member extending within and without said casing for operating said rotary member, a solid-state rectifier element in circuit with said resistance element, a cap covering said rectifier element, resilient means between said plates pressing said cap against said metal plate to conduct away heat from said element.

Claim 3

A device as claimed in claim 5 wherein said pressing means comprises a resilient elastic washer.

Claim 4

In an electric switching and power control device for portable tools, a casing, a metal plate and an insulation plate with said casing in parallel spaced relation, a potentiometer between said plates including a rotary contact and a circular resistance element, by-pass and power line contacts mounted on said insulating plate, a molded insulation rectilinearly movable trigger member having thereon cam means to operate said power line and by-pass contacts, a solid-state rectifier means between said plates and in circuit with said potentiometer, and means resiliently pressing said rectifier means in engagement with said metal plate to conduct heat from said rectifier means.

Claim 5

In an electric switching and power control device for portable tools, a casing, a metal plate and an insulation plate with said casing in parallel spaced relation, a potentiometer between said plates including a rotary contact and a circular resistance element, by-pass and power line contacts mounted on said insulating plate, a molded insulation rectilinearly movable trigger member having thereon cam means to operate said power line and by-pass contacts, a solid-state rectifier means between said plates and in circuit with said potentiometer, and means resiliently pressing said rectifier means in engagement with said metal plate to conduct heat from said rectifier means.

Claim 6

In an electric switching and power control device for portable tools, a casing, a pair of plates within said casing in parallel spaced relation, a potentiometer between said plates including a rotary contact and a circular resistance element, and a driven pinion to turn said rotary contact, by-pass and power lines contacts mounted on one of said plates, a molded insulation trigger member having a rack portion formed thereon engaging said pinion to rotate the pinion as the operating member is moved and also having thereon cam means to operate said power line and by-pass contacts, a solid-state rectifier means between said plates and in circuit with said potentiometer, and means resiliently pressing said rectifier means in engagement with one of said plates to conduct heat from said rectifier means.

Claim 7

In an electric switching and power control device for portable tools, a casing, a pair of plates within said casing in parallel spaced relation, a potentiometer between said plates including a rotary contact and a circular resistance element, and a driven pinion to turn said rotary contact, by-pass and power lines contacts mounted on one of said plates, a molded insulation trigger member having a rack portion formed thereon engaging said pinion to rotate the pinion as the operating member is moved and also having thereon cam means to operate said power line and by-pass contacts, a solid-state rectifier means between said plates and in circuit with said potentiometer, and means resiliently pressing said rectifier means in engagement with one of said plates to conduct heat from said rectifier means.

Claim 8

A speed control unit for an electrically operated hand manipulated tool, said unit comprising, a casing adapted to be mounted in thE housing of said tool, a trigger movably mounted on said casing for oscillating movement, a rotary potentiometer mounted on said casing in adjacent relation with said trigger, one or more components in said casing defining an electrical circuit connected with said potentiometer, which circuit is adapted to control the speed of an associated tool motor, a gear fixed on the rotary element of said potentiometer, a series of gear teeth on said trigger and extending along the direction of movement thereof, which gear teeth are in engagement with said gear and are thereby adapted to rotate said rotary element of the potentiometer upon actuation of said trigger.

Claim 9

A speed control unit for an electrically operated hand manipulated tool, said unit comprising, a casing adapted to be mounted in thE housing of said tool, a trigger movably mounted on said casing for oscillating movement, a rotary potentiometer mounted on said casing in adjacent relation with said trigger, one or more components in said casing defining an electrical circuit connected with said potentiometer, which circuit is adapted to control the speed of an associated tool motor, a gear fixed on the rotary element of said potentiometer, a series of gear teeth on said trigger and extending along the direction of movement thereof, which gear teeth are in engagement with said gear and are thereby adapted to rotate said rotary element of the potentiometer upon actuation of said trigger.

Claim 10

The speed control unit according to claim 5 wherein said circuit includes a controllable semi-conductor as one component thereof.

Claim 11

A speed control unit as claimed in claim 5 wherein said potentiometer has a rotary contact and a resistance element and wherein the teeth on said gear and on said trigger are arranged to cause the linear travel of said rotary contact over said resistance to exceed the linear travel of said trigger so that the motion of the rotary contact is multiplied with respect to the trigger.

Claim 12

A speed control unit as claimed in claim 7 having a pair of plates in parallel spaced relation between which the rotary contact of said potentiometer is mounted.

Claim 13

A speed control unit as claimed in claim 5 having power line and by-ass contacts, said trigger being of molded insulating material having cam means thereon first closing said power line contacts and later closing said bypass contacts as said potentiometer reaches the end of its rotation.

Claim 14

A speed control unit as claimed in claim 9 having a pair of plates in said casing in parallel spaced relation between which the rotary element of said potentiometer is mounted.

Claim 15

A variable speed control unit for a hand tool powered by an electric motor, which tool includes a housing having a handgrip portion provided with an opening to receive an operating trigger, said unit comprising, a casing adapted to be mounted in said handgrip housing portion, a trigger mounted on the casing for oscillating movement through said opening, a plurality of electrical components carried by said casing and defining a speed control circuit, and a rotary potentiometer arranged in said circuit so that operation of the former varies the speed of the associated tool motor, said potentiometer being mounted on said casing in adjacent relationship with said trigger, an arcuate gear formation on the rotary element of said potentiometer, a series of gear teeth on said trigger for movement therewith, which teeth are in meshing engagement with said gear formation thereby adapting the trigger for actuation of said potentiometer.

Claim 16

A variable speed control unit for a hand tool powered by an electric motor, which tool includes a housing having a handgrip portion provided with an opening to receive an operating trigger, said unit comprising, a casing adapted to be mounted in said handgrip housing portion, a trigger mounted on the casing for oscillating movement through said opening, a plurality of electrical components carried by said casing and defining a speed control circuit, and a rotary potentiometer arranged in said circuit so that operation of the former varies the speed of the associated tool motor, said potentiometer being mounted on said casing in adjacent relationship with said trigger, an arcuate gear formation on the rotary element of said potentiometer, a series of gear teeth on said trigger for movement therewith, which teeth are in meshing engagement with said gear formation thereby adapting the trigger for actuation of said potentiometer.

Claim 17

The unit according to claim 11 wherein said circuit includes as one component thereof a controllable semi-conductor.