Housing and switch for portable electric device

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view illustrating a portable electric tool embodying the present invention;

FIG. 2 is a top plan view of FIG. 1, with parts broken away and in section, and illustrating an operator’s hand.in position on the device; and

FIG. 3 is a view similar to FIG. 2 but showing the operator’s hand removed from the device.

BROAD STATEMENT OF THE INVENTION

Broadly described, the present invention relates to a portable electric device comprising a housing adapted to have an electric motor disposed therein, a handle rigid with said housing and adapted to be grasped by an operator, an on-off switch for said motor disposed on said handle and adapted to be actuated by said operator with his hand on said handle, a reversing switch for said motor and having an actuator movable through a path to reverse operation on” and “off” and for reversing the direction of rotation of said motor, respectively; the improvement in said tool wherein said on-off switch means includes a depressible trigger normally biased toward an “off” position and being actuated to the “on” position only when the operator’s hand is in place on the handle, said trigger being constructed to turn said on-off switch “off” when said operator releases his hand therefrom, said reversing switch of said motor, said path being disposed for interference with said operator’s hand when the latter is in position on said handle to actuate said on-off switch, whereby motor reversing is prevented when said motor is “on”.

In another aspect, the present invention relates to a portable electric power tool of the type having a housing adapted to have an electric motor disposed therein, a handle adapted to be grasped by the operator, tool means adapted to be driven by said motor, and on-off and reversing switch means for turning said motor “on” and “off” and for reversing the direction of- rotation of said motor, respectively; the improvement in said tool wherein said on-off switch means includes a depressible trigger normally biased toward an “off” position and being actuated to the “on” position only when the operator’s hand is in place on the handle, said trigger being constructed to turn said on-off switch “off” when said operator releases his hand therefrom, said reversing switch means including a pivoted lever movable past said trigger, said pivoted lever being prevented from movement past said trigger by interference with the operator’s hand when in place on said handle.

In still another aspect, the present invention relates to an electric powered device including a housing, electric motor means within said housing, first and second manually operable switches interconnected with said motor means and operable to control different operating characteristics thereof, said first switch including manually operable means movable through a path for operation thereof, said path being disposed for interference with the operator’s hand when the latter is in position to actuate said second switch, whereby actuation of said first switch is prevented when said second switch is actuated.

DETAILED DESCRIPTION

Referring now more specifically to the drawing, a portable, electric power tool, which is one type of device in which the present invention finds use, is illustrated generally at 11 in FIG. 1 and is seen to include a motor housing 13 having a gear case 15 suitably secured thereto. An electric motor (not shown) is disposed within the housing 13 and is powered from a suitable electric source connected thereto by a line cord 17. A handle 19 is rigid with the housing and facilitates easy operator manipulation and control of the tool 11.

The motor (not shown) is connected by a transmission (not shown) to a reciprocating slide (not shown) to which a saw blade 21 is adapted to be fixed. Since the details of the motor, transmission and slide form no part of the present invention, they are not illustrated nor described further here. However, for a better understanding thereof, reference may be made to ' the copending application of Thaddeus E. Bednarski, Ser. No. 745,064, filed July 16, 1968, and owned by the assignee of the present application.

Thus, when the motor is turned on, the blade 21 reciprocates. A shoe 23 on the front of the gear case 15 abuts against a workpiece to be cut by the blade 21 and stabilizes the tool 11.

The motor for the tool 11 is adapted to be turned “on” by an on-off switch 24 having a trigger 25 disposed on the handle 19. The switch trigger 25 is normally biased toward an “off” position, shown in FIGS. 1 and 3, but is movable to an “on” position, shown in FIG. 2. Thus, the trigger switch 25 preferably, but not necessarily, is located adjacent the top of the handle 19 and is adapted to be grasped and depressed by the forefinger 26 of an operator with his hand 28 on the handle 19 (see FIG. 2). When the operator releases the on-off switch trigger 25, the tool motor turns “off.”

In addition, a motor reversing switch 26 having a switch lever 27 is provided on the housing 13. This lever 27 is adapted to be manually moved through an arcuate path, illustrated in FIGS. 2 and 3, to reverse the polarity of the tool motor. In the case of a drill, screwdriver, impact wrench, or the like, where the tool output rotates, reversal of motor polarity would reverse the direction of rotation of this output. In the particular reciprocal saw illustrated here, the transmission which connects the motor to the blade 21 provides a different blade stroke length and correspondingly a different blade speed depending upon which direction the motor rotates. Again, reference may be made to applicant’s copending application for a better understanding of this transmission.

In either case, it will be appreciated that should the motor polarity be reversed when the motor is “on,” the surge in current through the motor brushes can shorten their life considerably. In addition, and more importantly, accidental reversal of the motor during motor operation in the tool 11 results both in a considerable mechanical reaction to the operator and a dramatic change in the output of the tool 11. Thus, the operator conceivably could lose control of and drop the tool 11 with resulting injury to himself, or to the tool 11, or both.

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4

In any event, it is important that provision be made that the motor of a portable device of this type cannot be reversed when it is “on.” In the past, this generally was accomplished by means of a mechanical or electrical interlock between the on-off and the reversing switches which prevents actuation of 5 the latter when the former is “on.” The present invention, however, takes a different approach and solves the problem by utilizing the spatial relationship of the switch trigger 25 and lever 27 to prevent the reversing switch lever 27 from being actuated when the switch trigger is “on.”

Thus, as shown, the switch trigger 25 and lever 27 are disposed such that when the operator’s forefinger 26 is holding the switch trigger 25 depressed and in the “on” position, as shown in FIG. 2, this finger is disposed in the path of movement of the reversing switch lever 27 so that the latter cannot be actuated, accidentally or otherwise. However, when the operator removes his forefinger 26 from the switch trigger 25, this trigger 25 returns to the “off” position, shown in FIG. 3. In this position, sufficient clearance exists to allow the reversing switch lever 27 to be actuated and the motor reversed.

It will be appreciated that the present invention effectively prevents motor reversal while the motor is “on” without any interlock, mechanical, electrical or otherwise, between the switches 24, 26, or the trigger 25 and lever 27. Thus, the danger of mechanical or electrical failure, which would allow the motor to be reversed when it is “on” is virtually eliminated. Furthermore, without additional parts, safety is preserved without increased cost.

While a preferred embodiment of the present invention has been illustrated and described above in detail, various additions, substitutions, modifications and omissions may be made thereto.