Brakes – Internal-resistance motion retarder – Using a rotary-type fluid damper
Reexamination Certificate
2002-05-17
2004-04-27
Siconolfi, Robert A. (Department: 3683)
Brakes
Internal-resistance motion retarder
Using a rotary-type fluid damper
C188S296000, C004S246200
Reexamination Certificate
active
06725984
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary damper for applying damping forces to a lid, a door, or the like when it is opened and closed.
2. Description of the Prior Art
One conventional rotary damper for applying damping forces to a lid, a door, or the like when it is opened and closed is disclosed in Japanese patent No. 2581655, for example. As shown in
FIG. 20
of the accompanying drawings, the disclosed rotary damper has a rotatable member
5
rotatable about its own axis. When the rotatable member
5
rotates counterclockwise to open a lid connected thereto, for example, a valve body
22
interposed between a vane
16
disposed on the outer circumferential surface of the rotatable member
5
and the inner circumferential surface of a cylindrical casing
2
moves clockwise with respect to the vane
16
, producing a fluid passage for a fluid to pass between the valve body
22
and the vane
16
through recesses
101
,
102
defined in at least one of the valve body
22
and the vane
16
. Therefore, when the lid is opened, since almost no resistance is developed to the fluid flowing through the fluid passage, the torque generated by the rotary damper is low, and the lid can be opened by a force corresponding to its weight.
When the rotatable member
5
rotates clockwise in the direction indicated by the arrow to close the lid from its open position, no gap is formed between the valve body
22
and the vane
16
, and the fluid passage which has been produced is closed. Therefore, the flow of the fluid is greatly limited, and the rotary damper generates a high torque.
The conventional rotary damper has a clearance or play
103
that exists until the valve body
22
is brought into contact with the vane
16
, closing the fluid passage. When the rotatable member
5
is rotated in the direction to close the lid, therefore, it takes the rotary damper a certain period of time before making a damping action based on the counterclockwise movement of the valve body
22
across the clearance
103
. While the valve body
22
is moving counterclockwise across the clearance
103
, the rotary damper does not produce a high torque and does not make a damping action. The range or period in which no damping action takes place is referred to as “backlash”.
When the keyboard lid of a piano which incorporates the conventional rotary damper is slightly opened and then released, for example, since the rotary damper does not immediately produce a damping action due to the backlash, it is dangerous disadvantage that the keyboard lid may possibly be closed quickly.
To solve the above problem of the conventional rotary damper, the applicant of the present application has proposed a rotary damper free of backlash as disclosed in Japanese patent No. 2894596. As shown in
FIG. 21
of the accompanying drawings, the proposed rotary damper includes a rotatable member
5
having a vane
16
which has a tip end of circular cross section, and a valve body
22
of C-shaped cross section fitted over and movably mounted on the tip end of the vane
16
.
When the rotatable member
5
of the rotary damper shown in
FIG. 21
rotates clockwise in the direction indicated by the arrow D, e.g., to open a lid connected to the rotary damper, the valve body
22
turns counterclockwise on the vane
16
due to a fluid resistance, a fluid passage
104
is produced between the valve body
22
and the inner circumferential surface of a cylindrical casing
2
. When the rotary member
5
rotates counterclockwise, e.g., to close the lid, the valve
22
turns clockwise on the vane
16
, closing the fluid passage
10
. Therefore, the rotary damper can make a damping action relatively quickly.
With the above rotary damper, however, there is a certain limitation on efforts to reduce the magnitude of the backlash because the valve body is angularly moved by only the resistance that is caused to the fluid upon rotation of the rotating body.
As an improvement designed to eliminate the backlash of the above rotary damper, there has been proposed a rotary damper disclosed in Japanese laid-open patent publication No. 2000-120747. The proposed rotary damper has a spring mounted on a valve body for immediately closing a fluid passage to make a quick damping action.
Specifically, as shown in
FIG. 22
of the accompanying drawings, the proposed rotary damper comprises a rotating body
5
, a pair of vanes
16
projecting radially outwardly from the outer circumferential surface of the rotating body
5
and having respective recesses
102
defined in their tip ends, a pair valve bodies
22
each of a substantially L-shaped cross section having an arcuate portion
105
and a radial portion
106
and covering at least of respective tip end surfaces of the vanes
16
, and a pair of springs
107
which are separate from the valve bodies
22
and interposed between the vanes and the valve bodies
22
. Since the two vanes
16
and various components combined therewith are identical to each other, only one of the vanes
16
and components combined therewith will be described below. When the rotary damper is in a normal position shown in
FIG. 22
, the spring
107
urges the radial portion
106
into close contact with a side
108
of the vane
16
which faces in the direction to exert damping forces. When the rotatable member
5
rotates counterclockwise in the direction indicated by the arrow A, i.e., rotates idly, a tongue
110
of the spring
107
is deformed in a clockwise direction opposite to the direction indicated by the arrow A under the pressure of a viscous fluid, displacing the radial portion
106
away from the side
108
.
The spring
107
includes a cross-sectionally channel-shaped fitting member
109
fitted in the recess
102
, and the tongue
110
projects outwardly from the fitting member
109
and has an outer end fitted in a slot
111
defined in the arcuate portion
105
of the valve body
22
. Therefore, the spring
107
is of a considerably complex structure.
If the rotary damper is small in size, then the space between the vane
16
and the valve body
22
for placing the spring
107
therein is also small in size. Therefore, the rotary damper cannot easily be assembled. The rotary damper is costly to manufacture because it is made up of a relatively large number of parts.
When the rotatable member
5
rotates idly in the direction indicated by the arrow A, the spring
107
is greatly deformed in the direction opposite to the direction indicated by the arrow A due to the resistance from the viscous fluid. After the rotary damper has been used over a long period of time, therefore, the spring
107
which is of a complex structure tends to be broken by fatigue at various locations on the fitting member
109
and the tongue
110
. Particularly, the tongue
110
is liable to suffer elastic fatigue. Consequently, the rotary damper is likely to develop backlash after it has been used over a long period of time.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rotary damper which will solve the problems of the conventional rotary dampers.
To achieve the above object, there is provided in accordance with the present invention a rotary damper comprising a casing having a fluid chamber filled with a fluid, a rotatable member disposed in the fluid chamber for rotation relative to the casing, a vane disposed on an outer circumferential surface of the rotatable member and extending in an axial direction thereof, the vane projecting toward an inner circumferential surface of the fluid chamber and having a first side and a second side opposite to the first side, a fluid passage for allowing the fluid to flow between the first side and the second side at or near a tip end of the vane, and a valve body mounted on the vane for selectively opening and closing the fluid passage, the valve body comprising a valve disposed in a position for closing the fluid passage and a spring for normally urging the valve in a direction to close the fluid passage, the valve and the
Merchant & Gould P.C.
Siconolfi Robert A.
Tok Bearing Co., Ltd.
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