Tool driving or impacting – Impacting devices – With anvil arranged to transmit torsional impact to tool
Reexamination Certificate
2000-02-16
2001-04-03
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
With anvil arranged to transmit torsional impact to tool
C173S093000, C173S176000
Reexamination Certificate
active
06209658
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motorized screw driving tool adapted to rotate a screw using the driving power of a motor, and more particularly to a motorized screw driving tool used for separation or mounting of tires of a vehicle or to drive a lift jack.
2. Description of the Prior Art
As well known, great force is required to separate tires of a vehicle from a body of the vehicle or to drive a lift jack used to a vehicle off of the ground. In particular, it is difficult for women and old or weak persons to carry out the task of separation tires of a vehicle or driving a lift jack.
In order to solve such a problem, a motorized screw driving tool utilizing the inertial force of a motor has recently been proposed. A representative example is disclosed in U.S. Pat. No. 4,947,939. This patent discloses the structure of a motorized screw bolt driving tool which is illustrated in FIG.
1
.
As shown in
FIG. 1
a
, the motorized screw bolt driving tool of the patent includes a motor
101
, and an inertia wheel mounted around a spindle coupled to the motor
101
such that it is rotated by the motor
101
. Fins
102
are mounted at one side of the inertia wheel such that they are developed by a centrifugal force of the inertia wheel. Each pin
103
is connected at one end thereof to an associated one of the fins
102
by means of a link. The other end of each pin
103
protrudes from the other side of the inertia wheel. An arch shaped brake element
104
is pivotally mounted at the other side of the inertia wheel such that its pivotal movement is prevent by the protruded ends of the pins
103
.
When the motor
101
rotates at a certain velocity or more, a centrifugal force capable of developing the fins
102
is generated. In this state, one of the pins
103
is retracted, so that the arch shaped brake element
104
pivots left or right, as shown in
FIG. 1
b.
Accordingly, the arch shaped brake element
104
, which pivots at a high velocity, enters, at one or the other end thereof, a recess formed in the spindle and strikes the spindle on the facing left or right side surface of the recess. As a result of, the spindle turns a nut, or the like, engaged in the end thereof by a strong force caused by an impact resulting from an inertial force of the arch shaped brake element
104
. Thus, a force sufficiently strong to separate a tire or to drive a lift jack is obtained.
However, the conventional motorized screw bolt driving tool has a structure in which the recess of the spindle is limited in its width. For this reason, it is difficult for the arch shaped brake element to engage in the recess at one time. Furthermore, the arch shaped brake element contacts the spindle in the recess in a point contact manner. As a result, a chattering phenomenon occurs which results in an instable starting force of the spindle.
After the arch shaped brake element and spindle recess are used for a certain period of time, they are abraded at the ends thereof. This results in an increase in the chattering phenomenon.
Moreover, the conventional motorized screw bolt driving tool has a structure in which the distance A between the centers of the arch shaped brake element and spindle is short, as shown in FIG.
2
. Since a power transmission is carried out with such a short distance, a chattering phenomenon occurs which prevents an effective transmission of the inertial force generated by the inertia wheel.
SUMMARY OF THE INVENTION
Therefore, a first object of the invention is to provide a motorized screw driving tool having a structure including a spindle and an inertial wheel mounted around the spindle, in which an inertial force generated by the inertia wheel is applied to the spindle at a position spaced apart from the center of the spindle by a large distance, thereby obtaining a high starting force.
A second object of the invention is to provide a motorized screw driving tool having a structure including a spindle and an inertia wheel mounted around the spindle, in which a power transmission member mounted to the inertia wheel and adapted to transmit power to the spindle has a greatly large engagement angle, thereby avoiding a chattering phenomenon of a starting force generated upon its initial power transmission.
A third object of the invention is to provide a motorized screw driving tool having a structure including a spindle and an inertia wheel mounted around the spindle, in which a power transmission member mounted to the spindle are in contact with each other in a round surface contact manner, thereby obtaining a durability.
In order to accomplish these objects, the present invention provides a motorized screw driving tool including a motor provided with a splined rotating shaft and adapted to generate a rotating force, an inertia wheel coupled to the rotating shaft of the motor and provided with power transmission means, and a spindle adapted to receive power receiving means, wherein: the power transmission means comprises: an actuating member resiliently mounted at one side of the inertia wheel by a spring and provided at opposite sides thereof with protruded pins, respectively, a pair of guide members adapted to guide a slide members having a guide slot receiving an associated one of the protruded pins of the actuating member, a cylindrical support member mounted at the other side of the inertia wheel and provided at opposite sides thereof with a pair of slots, respectively, a slide member slidably fitted in the cylindrical support member, a pair of cam members pivotally connected to the slide member and the slots of the cylindrical support member, and a pair of links each pivotally coupled at one end thereof to an associated one of the cam members by a pin and at the other end thereof to the associated pin of the actuating member, the links serving to link the cam members to the actuating member; and the power receiving means comprises a lever fixedly mounted around the spindle and provided with a groove with which the slide member can engage.
In accordance with the present invention, the inertial force from the inertia wheel is applied to the spindle at a position spaced apart from the center of the spindle by a very large distance. Accordingly, it is possible to obtain a strong starting force. Also, there is no or little chattering phenomenon generated during the power transmission by virtue of the guide function of the head having an inclined surface. Therefore, a stable starting force is generated. In particular, there is no element being abraded during the power transmission operation. Accordingly, there is an advantage in that a high durability is obtained which results in a lengthened use life.
REFERENCES:
patent: 4727780 (1988-03-01), Huang
patent: 4947939 (1990-08-01), Hung
patent: 5412546 (1995-05-01), Huang
patent: 5435398 (1995-07-01), Juan
patent: 5740892 (1998-04-01), Huang
patent: 5887666 (1999-03-01), Chen et al.
patent: 5915484 (1999-06-01), Hsieh
patent: 5941319 (1999-08-01), Juan
Dong Eun Electronics Co., Ltd.
Jacobson Price Holman & Stern PLLC
Smith Scott A.
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