Tool driving or impacting – Impacting devices – With anvil arranged to transmit torsional impact to tool
Reexamination Certificate
2000-06-01
2001-02-13
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
06186247
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drive assembly, and more particularly to a drive assembly for an electric hand tool.
2. Description of Related Art
A conventional drive assembly for an electric hand tool in accordance with the prior shown in
FIGS. 6-7
comprises a reversible motor (
600
) and a pinion gear (
60
) mounted on the motor shaft (not numbered) of the reversible motor (
600
). A hollow rotor (
70
) has a driven gear (
61
) formed on the end facing the reversible motor (
600
). The rotor (
70
) is mounted inside the hand tool such that the driven gear (
61
) is engaged with the pinion gear (
60
). A groove (
72
) is formed in one side of the rotor (
70
) to house a retainer (
80
). A first hook (
71
) extends out from each side of the rotor (
70
) adjacent to the side with the groove (
72
). A second hook (
81
) corresponding to the first hook (
71
) on the rotor (
70
) is formed on each end of the retainer (
80
). A spring is connected to each corresponding pair of first hooks (
71
) and second hooks (
81
). One end of a spring (
91
) is hooked on a first hook (
71
), and the other is hooked on the corresponding second hook (
81
). A drive block (
90
) is mounted in the rotor (
70
) inside the retainer (
80
). A main shaft (
92
) is rotatably mounted in the rotor (
70
). A transmission block (
921
) is securely mounted on one end of the main shaft (
92
) in the rotor (
70
). The drive block (
90
) drives the transmission block (
921
) and the main shaft (
92
) when the rotor (
70
) is rotated by the reversible motor (
600
).
The drive assembly for an electric hand tool as described above has several disadvantages.
1. The conventional drive assembly for an electric hand tool is noisy when the gears of the electric hand tool are operated, especially when changing the direction of rotation.
2. The whole rotor must be replaced with a new one when any one of the gears is broken. It will take a lot of time and costs a lot of money.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional drive assembly for an electric hand tool.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a drive assembly for an electric hand tool is provided. The drive assembly for an electric hand tool includes a rotor connected to a reversible motor whereby the rotor is driven. The rotor includes an H-shaped recess defined to receive a pawl device. One end of a shaft is pivotally mounted in the recess and is selectively engaged with the pawl device by the centrifugal force generated when the rotor rotates. The rotor in accordance with the present invention is directly connected to the reversible motor to reduce noise during operating and all the parts are detachable to reduce the cost of repair and replacement.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 5379851 (1995-01-01), 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
patent: 6119794 (2000-09-01), Chen
Rosenberg , Klein & Lee
Smith Scott A.
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