US 4,549,097 A · Electric safety switch

Abstract

A control switch proximate a support handle of a power driven machine provides for emergency deenergization of the machine without releasing the operator's grip on the support handle. The apparatus of this invention includes a control member (60) which moves from an at rest position along a selected direction (78) and against a first biasing force (70), (36) by motion of the operator's finger and further to an emergency off position by further motion of the operator's finger. A first biasing force (36), (70) continually urges the control member (60) to the at rest position. An activating means such as sliding contact switch (54), (56) and (66) is responsive to movement of the control member (60), and is connected to the driving source of the machine such that the driving source is in a nonoperating condition when the control member is in the at rest position and is in operating condition when the control member is moved to the energizing position. A second biasing force (84), (40) is provided which is stronger or in addition to and requires more force than the first biasing force to resist further motion. A deactivating means such as a normally closed emergency off switch (58) is responsive to further movement of the control member (60) to the emergency off position and will deenergize the machine such that a panic tightening of the operator's grip results in the machine being brought to a stop.

Claims9

Dependent claims

A control switch for mounting in a handle of a hand held power tool and being operated by a finger of an operator grasping such handle, such control switch providing for energization of such tool from a power source and for emergency deenergization of such tool without release of such finger, which comprises:

a switch housing for mounting in such handle;
a control member moveable in said switch housing by such finger sequentially along a selected direction, from an at rest "off" position to an energizing "on" position and to an emergency "off" position;
a first biasing means for resistive force against movement of said control member from said at rest "off" position to said emergency "off" position;
a further biasing means for resistive force against movement of said control member from said energizing "on" position to said emergency "off" position;
first actuating means responsive to movement of said control member from said at rest "off" position to said energizing "on" position for energizing such tool from such power source;
further actuating means responsive to movement of said control member from said energizing "on" position to said emergency "off" position for deenergizing such tool from such power source;
and
means for automatically releasably locking said control member at said emergency "off" position until reset by such operator.

5 more elements

A control switch for mounting in a handle of a hand held electrical tool having an electric motor for operation of such tool, such control switch being operated by a finger of an operator grasping such handle for energizing such motor from an electrical power source and for deenergizing such motor in emergencies without release by such finger, which comprises:

a switch housing for mounting within such handle;
a slide member mounted within said housing having first and further ends, said first end adapted to receive such finger of such operator, said slide member adapted for axial movement within said housing from an at rest "off" position to an energizing "on" position and then to an emergency "off" position;
a first biasing means carried by said slide member to provide a resistive force to said axial movement of said slide member;
an electrical slide contact carried by said slide member;
a first pair of spaced apart fixed electrical contacts mounted within said housing for engagement with said slide contact during said axial movement of said slide member for energizing such motor from such power source;
a further pair of normally contacting electrical contacts carried by said housing with one of said further pair moveable away from the other of said further pair upon motion of said slide member from said energizing "on" position to said emergency "off" position;
a further biasing means interposed between said contacts of said further pair to provide a resistive force against movement of said one contact of said further pair of contacts;
and
electrical connections for serially connecting said first and further pairs of electrical contacts with such motor and to said power source.

6 more elements

Dependencies are inferred from the claim text.

Electric safety switch

Life of this patent

Electric safety switch

Life of this patent

Abstract

Claims9