US3646298A

US3646298A - Switch operating trigger with integral biasing means and excessive force protection means

Info

Publication number: US3646298A
Application number: US66830A
Authority: US
Inventors: Edwin J Weber; Roderick F Bunyea
Original assignee: Black and Decker Manufacturing Co
Current assignee: Black and Decker Corp
Priority date: 1970-08-25
Filing date: 1970-08-25
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28

Abstract

A grass trimmer having an electric motor, a rotary blade, a handle extending from the motor, and a trigger switch in the grip portion of the handle. The trigger switch includes an ON-OFF switch for applying power to the motor and a trigger member. Integral with the trigger member is a resilient extension which abuts a fixed surface in the handle to provide a force biasing the trigger in the off direction to provide an improved ''''feel'''' for the operator and providing safer operation by avoiding a hair trigger effect.

Description

United tates Fattent 1 3,646,298 Weber et al. Feb. 29, 11972 [54] SWITCH OPERATING TRIGGER WITH 2,985,740 5/1961 Fisher et al. ..200/157 HNTEGRAL BEASING MEANS N 3,549,844 12/1970 Chambers ..200/157 EXCESSHVE FORCE PROTECTION FOREIGN PATENTS OR APPLICATIONS MEANS 1,812,748 8/1969 Germany ,200/l57 [72] lnventors: Edwin J. Weber, Baltimore; Roderick 1F. 33 237 3/ 953 Germany 200 57 Bunyea, Cockeysville, both of Md.

Primary ExaminerRobcrt A. Schaefer 73 A s Th 1 k d D k M f l S lgnce f g i iz S er acturmg Assistant ExaminerRobert A. Vanderhye i All0rneyLeonard Bloom, Joseph R. Slotnik and Edward D. [22] Filed: Aug. 25, 1970 Murphy [21] Applv No.: 66,830 [57] ABSTRACT A grass trimmer having an electric motor, a rotary blade, a 7

handle extending from the motor, and a trigger switch in the [58] Fieid 61 85 A 153 v grip portion of the handle. The trigger switch includes an ON- 206/153 1 OFF switch for applying power to the motor and a trigger member. Integral with the trigger member is a resilient extension which abuts a fixed surface in the handle to provide a [56] References cued force biasing the trigger in the off direction to provide an im- UNITED STATES PATENTS proved feel" for the operator and providing safer operation by avoiding a hair trigger effect. 3,390,242 6/1968 Koepke ..200/153 V 3,594,529 7/1971 Cartwright ..200/l72 A 4 Claims, 4 Drawing Figures Patented Feb. 29, 1972 INVENTORS EDWIN J. WEBER RODERICK F. BUNYEA SWITCH OEERATING TRIGGER WITH INTEGRAL BIASING MEANS AND EXCESSIVE FORCE PROTECTION MEANS The present invention relates to low cost electric motordriven devices which include a handle portion adapted to be grasped by an operator and having a trigger switch for controlling the operation ofthe motor.

In conventional trigger switches, it is customary to provide a spring for biasing the trigger to the OFF" position. This serves to prevent the trigger from being loose despite the necessary tolerance between the switching region in the power control switch and the portion of the trigger which operates the switch. This spring also provides a reactive force against the operators finger throughout the motion of the trigger. This is more satisfactory than a loose arrangement which may create the impression of sloppiness.

In many cases, the trigger member is permanently coupled to the switch operating member so that the spring which biases the switch to the OFF position may also be used to bias the trigger member in this manner. However, in the interest of reducing the cost of the device to the consumer, it is often desired to use a standard switch, such as a slide switch and to 7 control it by means of a trigger member which abuts and pushes against the slider button in the ON direction but which has some free movement when the switch slider is in its OFF position. To take up this slack, it is necessary to add an independent spring force which increases the cost, thus partially defeating the purpose of using the slide switch. It is the purpose of this invention to avoid the necessity for this extra cost and to provide an improved trigger for use in this design and in others where a biasing force applied directly to the trigger member may be desirable.

It is accordingly an object of this invention to provide an improved trigger switch including a low cost biasing means.

It is also an object to provide an improved trigger member which does not require an independent biasing member.

Another object is the provision of an improved, low cost handle and trigger switch assembly in which the trigger is biased to the normal position.

Further objects and advantages will become apparent as the description and illustration of this invention proceed.

Briefly, in accord with one embodiment of this invention, a handle and trigger assembly is provided wherein the trigger is pivotally mounted for movement within the handle. The trigger includes an exposed member for actuation by an operator and a rigid extension thereof for operating a power switch. In accord with this invention, a resilient extension is provided-integral with the trigger, which abuts a portion of the handle so as to be flexed when the trigger is moved by the operator. The resilient member is flexed a small amount even when the trigger is in the fully released position, thus providing a resistance to any movement of the trigger by the operator. This compensates for any looseness in the construction and provides the feel" desired by the operator. In the drawin FIG. I is a perspective view ofa grass trimmer which utilizes the present invention;

FIG. 2 is a perspective view ofan improved trigger in accord with this invention;

FIG. 3 is a partial cross-sectional view of the handle assembly of the trimmer of FIG. 1 showing the trigger in the OFF position; and

FIG. 4 is a view similar to FIG. 3 but showing the trigger in the ON position.

in FiG. l, a grass trimming device is illustrated as an exemplary application of the trigger switch of this invention. The trimmer shown comprises a cutting blade partially enclosed by a guard 11 and driven by an electric motor, not shown, which is enclosed within housing 12. A handle 13 extends from the housing and terminates at its upper end in a handle grip portion I4. A trigger 15 is provided for controlling the application of power to the electric motor. For example, the tool may be adapted for connection via an extension cord to an AC outlet or it may be adapted for battery power. In either case,

movement of the trigger 15 into the handle by the operator is effective to cause operation ofthe motor.

FIG. 2 illustrates the trigger of this invention and FIGS. 3 and 4 respectively show-the trigger 15 in its outer and inner positions within the handle. The trigger 15 comprises a trigger member 16 which is mounted within the handle 14 via a pivot 17. The trigger member I6 is shaped in the usual manner to provide a comfortable surface for the operator's finger during operation. The pivot 17 is integral with the trigger member and consists of a pair of round extensions on opposite sides of the trigger which rest in appropriate slots 18 formed in the internal structure of the handle I4.

The trigger 15 also includes an integral and relatively rigid extension 19 which serves as the switch operating member. As can be seen in FIG. 4, this extension is arranged to encounter the slide button 20 of a slide switch 21 as the trigger is depressed by the operator and shift the slide button. thus changing the connection to terminals 22 from OFF to ON. These terminals are appropriately connected between the power source and the motor so as to control the operation thereof. Although the member I9 is relatively rigid, it is noted that it may be slightly flexible upon the application of an unusually large force so as to reduce the possibility of breaking the slide button 20 or the switch 21. This flexing is illustrated in FIG. 4.

In particular accord with this invention, the trigger 15 also includes a second integral extension 23 which is normally straight as shown in FIG. 2 and must be flexed slightly in order to accommodate the trigger within the confines of its mounting location with the handle (FIG. 3). Thus the extension 23 serves 'to bias the trigger member 16 outwardly toward the OFF position at all normal positions of the trigger member. Outward movement of the trigger is limited by the

stops

24, 25. Accordingly, this member compensates for the free movement which would otherwise be present due to the space between the end of the operating extension 19 and the slide button 20. It is noted that this space is generally desired to provide some movement of the trigger before actual operation of the switch occurs.

The flexible extension 23 is madejust sufficiently flexible so as to allow the operator to depress the trigger freely and without obstruction, but at the-same time to provide enough resistance to movement for the operator to be aware of this force. This reactive force is generally preferred by almost all users of trigger operated devices. It will be noted in FIG. 4 that the degree of bending of the extension 23 has increased due to the inward movement of the trigger member 16 about the pivot 17.

It has been stated above that the trigger member 16, the

extensions

19 and 23, and the pivot 17 are integrally formed. Preferably, this trigger comprises an injection-molded plastic such as nylon which is formed by providing an appropriately shaped die and injecting the liquid material which is then cured into the shape illustrated in FIG. 2. In this manner, either this or similar materials may be formed easily into the precise shape desired and the biasing means desired in such triggers is automatically provided without further cost or assembly. It can be seen that the trigger member 16 is sufficiently thick to provide a relatively rigid body under any normally expectable finger pressure. The member 19 may be approximately O. 15-inch thick and only about l-inch long, thus providing a resistance to flexing which is sufficient to withstand most finger pressures but which will yield before the slide button breaks if an unusually high force is applied. The extension 23 must be on the order of 0.085-inch thick and about 1.4-inch long, thus providing a limited biasing force which is easily overcome by an operator's finger.

It will be noted that many modifications from the illustrated embodiment can be made without departing from the concept of this invention. For example, other types of pivoting or linear movement of the trigger may be accommodated with a basically similar flexible extension which provides the described biasing force. It is also noted that a slot could readily be formed in an extension of the member 19 to accommodate the slide button 20, in the event that it was desired to make use of the force of extension 23 to assist in returning the slide button 20 to the outboard position. As a further modification, the extension 23 itself could abut against a special member within the handle or it could be located at adifferent angular position within the handle, if desired. Such modifications also provide an initial trigger movement against a small force, thus avoiding the danger of a hair trigger device and increasing the safety of the unit. Accordingly it is intended in the appended claims to cover all such changes and modifications as may come within the true spirit and scope of this invention.

We claim:

1. A handle and trigger assembly for controlling the applica tion of power to an electric tool comprising:

mounting locations in said handle for a trigger member and a power switch; an opening in the surface'of said handle; a trigger member comprising a single body of insulating material mounted within said handle having a pivot, and including a first member integral with said pivot extending through said opening for movement between an ON position and an OFF position by an operator;

at second member integral with said pivot and arranged to operate said power switch upon movement of said trigger member between said positions, said second member being rigid with said first member under normal pressure by said operator and being adapted to flex upon the application of higher force levels whereby said second member protects said power switch against damage; and

a third member integral with said pivot and bearing against a fixed surface within said handle to provide a biasing force urging said trigger member into said OFF" position, said second extension being flexible under ordinary operator finger pressure.

2. A handle and trigger assembly as claimed in claim I wherein said second member is spaced from said power switch in said OFF" position.

3. A finger-actuatable trigger for controlling a power switch in an electric tool comprising a single body of insulating material including a pivot portion adapted to be rotatably mounted within a handle;

a first radial extension from said pivot providing a trigger member engageable by an operator for movement between an ON" position and an OFF position;

a second radial extension from said pivot arranged to operate a power switch upon movement of said trigger member between said positions; and

a third radial extension from said pivot arranged to bear against a fixed surface, said third extension being flexible so as to provide a biasing force urging said trigger member into said OFF" position.

4. A trigger as claimed in claim 3 wherein said second radial extension is more flexible than said trigger member and less flexible than said third radial extension.

Claims

1. A handle and trigger assembly for controlling the application of power to an electric tool comprising: mounting locations in said handle for a trigger member and a power switch; an opening in the surface of said handle; a trigger member comprising a single body of insulating material mounted within said handle having a pivot, and including a first member integral with said pivot extending through said opening for movement between an ''''ON'''' position and an ''''OFF'''' position by an operator; a second member integral with said pivot and arranged to operate said power switch upon movement of said trigger member between said positions, said second member being rigid with said first member under normal pressure by said operator and being adapted to flex upon the application of higher force levels whereby said second member protects said power switch against damage; and a third member integral with said pivot and bearing against a fixed surface within said handle to provide a biasing force urging said trigger member into said ''''OFF'''' position, said second extension being flexible under ordinary operator finger pressure.

2. A handle and trigger assembly as claimed in claim 1 wherein said second member is spaced from said power switch in said ''''OFF'''' position.

3. A finger-actuatable trigger for controlling a power switch in an electric tool comprising a single body of insulating material including a pivot portion adapted to be rotatably mounted within a handle; a first radial extension from said pivot providing a trigger member engageable by an operator for movement between an ''''ON'''' position and an ''''OFF'''' position; a second radial extension from said pivot arranged to operate a power switch upon movement of said trigger member between said positions; and a third radial extension from said pivot arranged to bear against a fixed surface, said third extension being flexible so as to provide a biasing force urging said trigger member into said ''''OFF'''' position.