Tool driving or impacting – Impacting devices – With anvil arranged to transmit torsional impact to tool
Reexamination Certificate
2002-04-26
2002-10-15
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
With anvil arranged to transmit torsional impact to tool
C173S213000
Reexamination Certificate
active
06464017
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a transmission mechanism for pneumatic tool, and more particularly to a transmission mechanism that can be conveniently mounted into a housing of a pneumatic tool and enables the pneumatic tool to operate more smoothly.
A general pneumatic tool
100
usually includes a transmission mechanism
1
′ shown in
FIGS. 1 and 2
show transmission mechanism
1
′ mainly includes a case main
1
in which a front cover bearing
19
, a front cover
20
, a main body
12
, a sleeve seat
13
, a sleeve
14
, and a spring
15
are sequentially mounted from bottom to top, and a transmission shaft
18
having an end projected from a top of the casing to extend through an oil-retaining shaft sleeve
17
via a washer
16
. When the entire transmission mechanism
1
′ has been mounted in a housing of the pneumatic tool
100
, impact forces from two sources, namely, the transmission shaft
18
, the washer
16
, and the oil-retaining shaft sleeve
17
, as well as the sleeve seat
13
, the sleeve
14
, and the casing
11
, are transmitted to the main body
12
, the front cover bearing
19
, and the front cover
20
via two ends of the spring
15
. When the pneumatic tool
100
is operated, each movement of the transmission mechanism
1
′ would cause an impact on the main body
12
to result in deformation or breaking thereof, and on the front cover bearing
19
and the front cover
20
to result in undesired loosening and deformation thereof.
When the transmission mechanism
1
′ rotates at a speed as high as 7000 rpm, the transmission shaft
18
, the washer
16
, and the oil-retaining shaft sleeve
17
are subjected to an action force of about 7 kgs from the spring
15
and therefore tightly contact with one another to result in reduced clearances and increased friction among them, as well as undesired heating of these components. The transmission mechanism
1
′ therefore has slowed rotational speed, increased noise, and reduced torque output.
It is noted the main body
12
, the sleeve seat
13
, the sleeve
14
, the spring
15
, the washer
16
, the oil-retaining shaft sleeve
17
, and the transmission shaft
18
of the above-described conventional transmission mechanism
1
′ for pneumatic tool
100
for assembled without being holding in place in the casing
11
′ by locating means. When the primarily assembled transmission mechanism
1
′ is to be mounted in this to be of the pneumatic tool
100
, specially designed tools must be used. Moreover, the components of the primarily assembled transmission mechanism
1
′ tend to separate from one another during movement or transport before being mounted into the housing of the pneumatic tool
100
, resulting in inconveniences and additional time and labor in subsequent assembling.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide an improved transmission mechanism for pneumatic tool that is able to overcome the problems of deformed or broken main body, over tightly contacted transmission shaft, washer, and oil-retaining shaft sleeve, and inconvenient assembling, so that the pneumatic tool could be more easily assembled and smoothly operated.
To achieve the above and other objects, the transmission mechanism for pneumatic tool according to the present invention mainly includes a casing that has an extended length to allow for the provision of a locating groove along an inner peripheral surface close to a top thereof for receiving a C-shaped retaining ring therein, and a washer that is provided at one side facing toward the top of the casing with a boss portion. After the transmission mechanism is assembled, the C-shaped retaining ring firmly bears against one side of the washer around the boss portion to hold the transmission shaft in place in the casing.
With the C-shaped retaining ring, (1) the whole transmission mechanism is highly stably assembled and can therefore be more conveniently mounted in the housing of the pneumatic tool without easily separated components during transport and mounting of the transmission mechanism; (2) undesired deformation or breaking of the main body caused by impact forces transmitted thereto from the transmission shaft via the spring can be eliminated; and (3) the washer is protected from overly tight contact with said oil-retaining shaft sleeve to avoid undesired friction, noise, heating, and reduced torque output of said transmission mechanism.
REFERENCES:
patent: 3533479 (1970-10-01), Madsen
patent: 4313505 (1982-02-01), Silvern
patent: 5012878 (1991-05-01), Anderson
patent: 5370194 (1994-12-01), Anderson
patent: 6135212 (2000-10-01), Georgiou
patent: 6178853 (2001-01-01), Huang
patent: 6283226 (2001-09-01), Chen
Rosenberg , Klein & Lee
Smith Scott A.
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