Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2002-05-20
2004-02-03
Friedhofer, Michael (Department: 3723)
Electricity: circuit makers and breakers
Electric switch details
Actuators
C200S293100, C200S329000
Reexamination Certificate
active
06686548
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a quick shut-off device for a grinding tool and includes a pushing member connected to a spring so that when the user pushes an end of the pushing member, the switch of the grinding tool is then shut off immediately.
BACKGROUND OF THE INVENTION
A conventional portable grinding tool is shown in FIG.
1
and generally includes a handle
70
with a driving device
72
connected to a first end of the handle
70
and a grinding wheel
71
is connected to and driven by the driving device
72
. A switch
73
is connected to a second end of the handle
70
so that the driving device
72
is activated or stopped by operating the switch
73
. The grinding tool is heavy so that the user usually holds the handle
70
with his/her two hands. In a situation when the grinding wheel
71
is broken by an impact with a hard object, the debris could fly to hit the user at a high speed and the user has to shut off the driving device
72
as soon as possible. However, when the grinding tool is operated in a narrow space, the two hands of the user are not convenient to remove from the handle
70
to operate the switch
73
. Therefore, how to shut off the driving device
72
within a short period of time when the emergency situation happens is important.
Referring to
FIG. 2
which shows another type of the conventional grinding tool
80
and the switch
81
is connected to a surface of the handle
82
and the switch
81
extends from the surface of the handle
82
. The switch
81
is easily to be touched or activated when putting the tool
80
on the ground, or by unintentional access. This will activate the grinding wheel
83
without expectation and could hurt the grinding wheel
83
and/or the people around the grinding tool
80
.
The present invention intends to provide a quick shut-off device for the grinding tool that has a pushing member on the handle and can be touched to shut off the electric power to stop the driving device.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a grinding tool which comprises a handle having a driving device at a first end of the handle so as to drive a grinding wheel. An opening is defined in the handle and a switch device is received in the opening. A cover is engaged with the opening and has a recess de fined in an outer periphery of the cover. A hole is defined through the cover.
A pushing member is slidably engaged with the recess and a stepped protrusion extends from an underside of a first end of the pushing member so as to be engaged with an inner periphery of the hole. A gap is defined between a second end of the pushing member and a surface defining the recess.
An activation member extends through the hole and is located between the stepped protrusion and the second end of the pushing member. The activation m ember is fixed to the pushing member and has a convex which contacts the switch device.
A spring has a first end connected to the cover and a second end of the spring is connected to the activation member.
REFERENCES:
patent: 4006334 (1977-02-01), Robotham et al.
patent: 4380693 (1983-04-01), Kuhlmann et al.
patent: 4906804 (1990-03-01), Theimer
patent: 4973807 (1990-11-01), Stabler et al.
Friedhofer Michael
Rosenberg , Klein & Lee
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