Rotary shafts – gudgeons – housings – and flexible couplings for ro – Fluid coupling
Reexamination Certificate
1998-12-16
2001-04-10
Melius, Terry Lee (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Fluid coupling
C188S296000, C188S308000, C016S050000
Reexamination Certificate
active
06213881
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a damper device for use on the door of a container to apply damping forces to the angular movement of the door in terminal ranges of opening and closing movements of the door, or for use on an electrically powered tool such as an electrically powered saw or plane to reduce shocks in terminal ranges of reciprocating movements thereof.
2. Description of the Related Art
Heretofore, some containers are equipped with a damper device mounted on the door for preventing the door from banging against the door frame when the door is closed. Since the damper device operates only when the door is closed, however, the damper device is not active when the door is quickly opened. When the door is quickly opened, therefore, the door tends to hit a stop, producing undesirable noise or causing damage to itself or the stop. For producing a damping action in a terminal range of the opening movement of the door, the door needs to incorporate another separate damper device separately from the existing damper device which operates only when the door is closed.
There has not been known any example in which the above damper device is applied to a reciprocally movable electrically powered tool. Heretofore, it has been customary for the user of a reciprocally movable electrically powered tool to empirically control forces produced by the tool in terminal regions of its reciprocating actions to avoid unwanted impacts or damage to the tool. However, controlling forces produced by the tool in terminal regions of its reciprocating actions needs a skilled experience on the part of the user, and is physically fatiguing to the user.
Installing two damper devices on one door is highly costly. In addition, it is a complex task to install two damper devices on one door and also to perform maintenance on the two damper devices mounted on the door. There has been a demand for a single damper device which is capable of producing a damping force in both terminal ranges of opening and closing movements of a door on which the damper device is installed.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a damper device which is capable of generating a damping force in both terminal ranges of opening and closing movements or reciprocating movements of an apparatus on which the damper device is installed.
To achieve the above object, there is provided a damper device comprising a cylindrical casing, a rotor partly housed in the casing, a viscous fluid filled in the cylindrical casing around the rotor, and torque generating means for generating a torque during a rotating stroke of the rotor, the torque generating means including fluid torque adjusting means for producing a relatively large torque in a terminal range of each of the rotating strokes in normal and reverse directions of the rotor and a relatively small torque in other range of each of the rotating strokes. Therefore, if the damper device is installed on a door, then the damper device can produce a damping force in terminal periods of opening and closing movements of the door, thereby preventing the door from banging against a stopper or a door frame when the door is fully closed or opened. Furthermore, since the damper device generates a relatively small torque in the rotating strokes in the normal and reverse directions, it is possible not to apply a damping force in a period other than the terminal periods of opening and closing movements of the door. As a result, the door can be opened and closed with a small force.
The torque generating means may have a first ridge extending axially on an outer surface of the rotor and having a radially outer surface held in sliding contact with an inner surface of the casing, and the fluid torque adjusting means may comprise a first land extending axially on the inner surface of the casing, a pair of first axial grooves defined axially in a radially inner end of the first land and spaced circumferentially from each other, a pair of first needle valves loosely fitted in the first axial grooves, respectively, for movement in the width direction of the first axial grooves, and a first circumferential groove defined circumferentially on the outer surface of the rotor, the first circumferential groove being positioned out of facing relation to at least one of the first needle valves in the terminal range of each of the rotating strokes. When the at least one of the needle valves is held against the outer surface of the rotor in the terminal range, the one of the first needle valves and the first ridge jointly divide an interior space of the casing into two chambers, for effectively preventing the viscous fluid from moving between the chambers to produce the relatively large torque. The fluid torque adjusting means of the above structure can easily be incorporated in the damper device, and can reliably generate a relatively large torque in the terminal range of each of the rotating strokes.
Alternatively, the torque generating means may have a second land extending axially on an inner surface of the casing and having a radially inner surface held in sliding contact with an outer surface of the rotor, and the fluid torque adjusting means may comprise a third land extending axially on the outer surface of the rotor, a pair of second axial grooves defined axially on a radially outer end of the third land on the rotor and spaced circumferentially from each other, a pair of second needle valves loosely fitted in the second axial grooves, respectively, for movement in the width direction of the second axial grooves, and a second circumferential groove defined circumferentially in the inner surface of the casing, the second cylindrical groove being positioned out of facing relation to at least one of the second needle valves in the terminal range of each of the rotating strokes. When the at least one of the second needle valves is held against the inner surface of the casing in the terminal range, the one of the second needle valves and the second land of the casing jointly divide an interior space of the casing into two chambers for effectively preventing the viscous fluid from moving between the chambers to produce the relatively large torque. The fluid torque adjusting means of the above structure can easily be incorporated in the damper device, and can reliably generate a relatively large torque in the terminal range of each of the rotating strokes.
Further alternatively, the torque generating means may have a fourth land extending axially on an inner surface of the casing and having a radially inner surface held in sliding contact with a outer surface of the rotor, and the fluid torque adjusting means may comprise a pair of second ridges extending axially on the outer surface of the rotor, a pair of valve bodies loosely mounted on the second ridges, respectively, and a third circumferential groove defined circumferentially in the inner surface of the casing, the third cylindrical groove being positioned out of facing relation to at least one of the needle valves in the terminal range of each of the rotating strokes. When the at least one of the valve bodies is held against the inner surface of the casing in the terminal range, the one of the valve bodies and the second ridges jointly divide an interior space of the casing into two chambers for effectively preventing the viscous fluid from moving between the chambers to produce the relatively large torque. The fluid torque adjusting means of the above structure can easily be incorporated in the damper device, and can reliably generate a relatively large torque in the terminal range of each of the rotating strokes.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
REFERENCES:
patent: 4653141 (1987-03-01), Converse
patent: 4825503 (1989-05-0
Sasa Hirozumi
Takahashi Kenji
Melius Terry Lee
Thompson Kenneth
Tok Bearing Co., Ltd.
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