U.S. patent application number 09/907277 was filed with the patent office on 2002-01-24 for rotary damper.
This patent application is currently assigned to TOK BEARING CO., LTD. Invention is credited to Kobori, Takeaki, Sasa, Hirozumi.
Application Number | 20020007993 09/907277 |
Document ID | / |
Family ID | 18713370 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007993 |
Kind Code |
A1 |
Kobori, Takeaki ; et
al. |
January 24, 2002 |
Rotary damper
Abstract
To provide a rotary damper in which a viscous fluid does not
leak from between an inner end face of a land and an outer
circumferentialsurface of a rotatable member, and a decrease in
torque caused by an eccentric rotation of the rotating member is
prevented. The rotary damper comprises: the rotatable member being
relatively rotatable with respect to a casing, the proximal portion
of the rotatable member being accommodated in a chamber of the
case; a ridge member extending axially along and projectiong
radially outwardly from an outer circumferential surface of the
proximal portion of the rotatable member, the ridge member having a
radially outer end face disposed for sliding contact with an inner
circumferential surface of the chamber; and the land extending
axially along and projecting inwardly from the inner
circumferential surface of the chamber, the land having a face
transverse face transversely with respect to the rotational
direction of the rotatable member. The ridge member and the land
divide an interior of the chamber into a compression compartment
and a decompression compartment, the volume of these compartment
being variable complementarily to each other in response to the
relative rotation of the rotatable member and the casing. A spacer
is interposed between the land and the proximal portion of the
rotatable member and adapted to be pressed against the outer
circumferential surface o the proximal portion and the transverse
face of the land by the pressure built up in the compression
compartment in response to rotation of the rotatable member.
Inventors: |
Kobori, Takeaki; (Tokyo,
JP) ; Sasa, Hirozumi; (Tokyo, JP) |
Correspondence
Address: |
MERCHANT, GOULD, SMITH, EDELL
WELTER & SCHMIDT, P.A.
3200 IDS Center
80 South 8th Street
Minneapolis
MN
55402
US
|
Assignee: |
TOK BEARING CO., LTD
|
Family ID: |
18713370 |
Appl. No.: |
09/907277 |
Filed: |
July 17, 2001 |
Current U.S.
Class: |
188/290 |
Current CPC
Class: |
F16F 9/145 20130101;
B60G 2202/22 20130101; E05Y 2201/21 20130101; E05Y 2201/256
20130101; E05Y 2900/531 20130101; E05Y 2201/266 20130101 |
Class at
Publication: |
188/290 |
International
Class: |
F16D 057/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 19, 2000 |
JP |
2000-218418 |
Claims
What is claimed is:
1. A rotary damper, comprising: a casing having a chamber defined
therein; a viscous fluid filled in said chamber; a rotatable member
being relatively rotatable with respect to said casing, the
proximal portion of said rotatable member being accommodated in
said chamber; a ridge member extending axially along and projecting
radially outwardly from an outer circumferential surface of the
proximal portion of said rotatable member, said ridge member having
a radially outer end face disposed for sliding contact with an
inner circumferential surface of said chamber; and a land extending
axially along and projecting inwardly from said inner
circumferential surface of said chamber, said land having a
transverse face transversely with respect to the rotational
direction of said rotatable member, said ridge member and said land
dividing an interior of said chamber into a compression compartment
and a decompression compartment, the volume of said compression and
decompression compartments being variable complementarily to each
other in response to said relative rotation of said rotatable
member and said casing, a spacer interposed between the land and
the proximal portion of said rotatable member and adapted to be
pressed against the outer circumferential surface of the proximal
portion of said rotatable member and said transverse face of said
land by the pressure built up in said compression compartment in
response to rotation of said rotatable member.
2. The rotary damper according to claim 1, wherein a side face on
the side of said compression compartment of said land forms said
transverse face, and said spacer is disposed so as to cover an
inner end face and said transverse face of said land.
3. The rotary damper according to claim 2, wherein said spacer has
a portion along said transverse face of said land, said portion has
an end face confronting the inner circumferential surface of said
chamber to keep a gap therebetween.
4. The rotary damper according to claim 1, wherein said land is
provided with an inward protrusion on the inner end face thereof, a
side face on the side of said compression compartment of said
inward protrusion forms said transverse face and said spacer is
mounted on the inner end face of said land while engaging with said
inward protrusion.
5. The rotary damper according to claim 4, wherein said spacer has
a portion on the side of said compression compartment, said portion
has an end face confronting the inner end face of the land to keep
a gap therebetween.
6. The rotary damper according to any one of claims 1 to 5, wherein
said spacer is made from at least one of a group consisting of
plastic, rubber-like material and metal.
7. The rotary damper according to claim 6, wherein said plastic
material is a fluorine-containing plastic.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotary damper for
applying damping forces to, for example, a door or a cover when the
door or the cover is opened or closed.
[0003] A conventional rotary damper 1 as shown in FIG. 15 has a
ridge member 15 provided on an outer circumferential surface of a
proximal portion 5 of a rotatable member 4 and a land 11 provided
on an inner circumferential surface of a chamber 3. When the
rotatable member 4 rotates to a high torque production side (in the
clockwise direction in the drawing), the pressure of a viscous
fluid 7 increases in a compression compartment 3a of the chamber 3,
by which a high torque is obtained.
[0004] Also, a conventional rotary damper disclosed in Japanese
Patent Laid-Open No. 2000-46087, as shown in FIG. 16, has a
construction such that a substantially cylindrical sleeve 5 made of
a synthetic resin is disposed between an inner end face 21a of a
partition wall portion 21 of a casing 2 and the outer
circumferential surface if a rotating shaft 3 provided with a vane
member 4. Such a sleeve 5 can prevent a gap from developing between
the inner end face 21a of the partition wall portion 21 of the
casing 2 and the outer circumferential surface of the rotating
shaft 3 because it absorbs irregularities on the inner end face 21a
of the partition wall portion 21 by means of the elastic force
thereof. As a result, even when a viscous fluid with a low
viscosity is used, a high torque can be produced.
[0005] However, what we call a one-blade rotary damper having one
ridge member 15 as shown in FIG. 15 has a problem described below.
When the rotatable member 4 rotates to the high torque production
side to increase the pressure of the viscous fluid 7 in the
compression compartment 3a, the proximal portion 5 of the rotatable
member 4 rotates eccentrically in the direction indicated by the
arrow mark in FIG. 15, so that a clearance between the outer
circumferential surface of the proximal portion 5 and the inner end
face of the land 11 increases. Thereby, a bypath flow of the
viscous fluid 7 from the clearance, which is only of a negligible
amount intrinsically, is increased, so that the torque in the high
torque production region decreases. As a result, sufficient damping
action necessary when a door etc. provided with the rotary damper
is closed cannot be accomplished.
[0006] Also, the rotary damper shown in FIG. 16 has a problem
described below. The long-term use of the rotary damper develops a
gap between the inner end face 21a of the partition wall portion 21
and the sleeve 5 by means of abrasion, so that the viscous fluid
leaks from between the slidingly contacting surfaces of the
rotating shaft 3 and the sleeve 5. As a result, the torque in the
high torque production region decreases.
[0007] Accordingly, an object of the present invention is to
provide a rotary damper in which even if the rotary damper is used
for a long period of time, a clearance between the inner end face
of partition wall and the outer circumferential surface of rotating
shaft can be kept in a given range, whereby the torque in the high
torque production region can be prevented from decreasing.
SUMMARY OF THE INVENTION
[0008] To solve the above problems, the present invention as
claimed in claim 1 provides a rotary damper comprising: a casing
having a chamber defined therein; a viscous fluid filled in the
chamber; a rotatable member being relatively rotatable with respect
to the casing, the proximal portion of the rotatable member being
accommodated in the chamber; a ridge member extending axially along
and projecting radially outwardly from an outer circumferential
surface of the proximal portion of the rotatable member, said ridge
member having a radially outer end face disposed for sliding
contact with an inner circumferential surface of the chamber; and a
land extending axially along and projecting inwardly from said
inner circumferential surface of the chamber, the land having a
transverse face transversely with respect to rotational direction
of the rotatable member, the ridge member and the land dividing an
interior,of the chamber into a compression compartment and a
decompression compartment, the volume of the compression and
decompression compartments being variable complementarily to each
other in response to the relative rotation of the rotatable member
and the casing, a spacer interposed between the land and the
proximal portion of the rotatable member and adapted to be pressed
against the outer circumferential surface of the proximal portion
of the rotatable member and the transverse face of the land by the
pressure built up in the compression compartment in response to
rotation of the rotatable member.
[0009] Even if a spacer portion on the outer circumferential
surface side of the proximal portion of the rotatable member is
worn by the long-term use of the rotary damper, the spacer can be
pressed against the outer circumferential surface of the proximal
portion of the rotatable member and the transverse face of the land
by the pressure built up in the compression compartment.
[0010] In the present invention as claimed in claim 2, a side face
on the side of the compression compartment of the land forms the
transverse face, and the spacer is disposed so as to cover the
inner end face and the side face of the land. Therefore, since the
spacer is disposed so as to straddle the land, the spacer does not
come off from the land under the pressure on the compression
compartment side.
[0011] In the present invention as claimed in claim 3, the spacer
has a portion along the side fact of the land and such portion has
an end face confronting the inner circumferential surface of the
chamber to keep a gap thgerebetween. Thereby, the spacer can be
pressed against the outer circumferential surface of the proximal
portion of the rotatable member and the side face of the land by
the pressure built up in the compression compartment in such a
manner as to float from the inner end face of the land.
[0012] In the present invention as claimed in claim 4, the land is
provided with an inward protrusion on the inner end face thereof, a
side face on the side of the compression compartment of the inward
protrusion forms the transverse face, and the spacer is mounted on
the inner end face of the land while engaging with the inward
protrusion. Therefore, since the spacer is disposed so as to engage
with the inward protrusion, the spacer does not come off from the
land under the pressure on the compression compartment side.
[0013] In the present invention as claimed in claim 5, the spacer
has a portion on the side of the compression compartment, such
portion has an end face confronting the inner end face of the land
to keep a gap therebetween. Thereby, the spacer is pressed against
the outer circumferential surface of the proximal portion of the
rotatable member and the inward protrusion by the pressure built up
in the compression compartment in such a manner as to float from
the inner end face of the land.
[0014] In the present invention as claimed in claim 6, the spacer
is made from at least one of a group consisting of plastic,
rubber-like material and metal. By forming the spacer of such a
material, the spacer can be pressed reliably against the outer
circumferential surface of the proximal portion of the rotatable
member and the transverse of the land by the pressure built up in
the compression compartment.
[0015] In the present invention as claimed in claim 7, the plastic
material is a fluorine-containing plastic material. This offers an
advantage that friction between the outer circumferential surface
of the proximal portion of the rotatable member and the spacer can
be decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a longitudinal sectional view showing a first
embodiment of a rotary damper in accordance with the present
invention;
[0017] FIG. 2 is a transverse sectional view of a rotary damper in
accordance with the first embodiment;
[0018] FIG. 3 is the transverse )sectional view of the rotary
damper in accordance with the first embodiment;
[0019] FIG. 4 is the transverse sectional view of the rotary damper
in accordance with the first embodiment;
[0020] FIG. 5 is the transverse sectional view of the rotary damper
in accordance with the first embodiment;
[0021] FIG. 6 is a graph showing a torque curve of the rotary
damper in accordance with the first embodiment;
[0022] FIG. 7 is a graph showing a torque curve of the rotary
damper without any spacer in the first embodiment;
[0023] FIG. 8 is a transverse sectional view showing a second
embodiment of a rotary damper in accordance with the present
invention;
[0024] FIG. 9 is a transverse sectional view of the rotary damper
in accordance with the second embodiment;
[0025] FIG. 10 is a transverse sectional view showing a first
modification of the rotary damper in accordance with the first
embodiment of the present invention;
[0026] FIG. 11 is a transverse sectional view showing the first
modification of the first embodiment;
[0027] FIG. 12A is a transverse sectional view showing a second
modification of a rotary damper in accordance with the first
embodiment of the present invention, and FIG. 12B is a partially
enlarged view of FIG. 12A;
[0028] FIG. 13A is a transverse sectional view showing a first
modification of a rotary damper in accordance with the second
embodiment of the present invention, and FIG. 13B is a partially
enlarged view of FIG. 13A;
[0029] FIG. 14A is a transverse sectional view showing a third
modification of a rotary damper in accordance with the first
embodiment of the present invention, and FIG. 14B is a partially
enlarged view of FIG. 14A;
[0030] FIG. 15 is a transverse sectional view of a conventional
rotary damper; and
[0031] FIG. 16 is a transverse sectional view of the conventional
rotary damper.
DETAILED DESCRIPTION OF TOE PREFERRED EMBODIMENTS
[0032] Embodiments of the present invention will be described with
reference to the accompanying drawings. FIGS. 1 to 5 show a first
embodiment of a rotary damper in accordance with the present
invention. FIG. 1 is a longitudinal sectional view of the rotary
damper of this embodiment, and FIGS. 2 to 5 are transverse
sectional views of the rotary damper of this embodiment, showing a
state in which a rotatable member rotates. Also, FIGS. 6 and 7 arc
graphs showing torque curves of the rotating damper of this
embodiment and a rotary damper of a comparative example.
[0033] As shown in FIGS. 1 to 5, a rotary damper 1 in accordance
with the first embodiment of the present invention has a
construction such that a proximal portion 5 of a rotatable member 4
is accommodated in a chamber 3 defined within a casing 2, and the
chamber 3 is filled with a viscous fluid 7 such as silicone oil
with a high viscosity.
[0034] An end portion 2a forming, the bottom of the chamber 3
within the casing 2 is closed, and a bearing recess 8 is formed in
the center thereof. One end 2b of the casing 2 is open, and is
sealed by an end cap 10 fixedly fitted to the open end 2b via a
partition wall 9 and a flanged bush 14. Also, a land 11 is provided
to extend axially along and project radially inwardly from the
inner circumferential surface of the chamber 3. Both of side faces
11a and 11b of the land 11 extend in the radial direction of the
casing 2, and both of the side faces are directed to the center O,
and an angle made by the side faces is about 90 degree.
[0035] The rotatable member 4 has a proximal portion 5 incorporated
in the chamber 3 and an extending portion 6 extending from the
proximal portion 5, passing through the partition wall 9, the
flanged bush 14 and the end cap 10, and thus projecting to the
outside of the casing 2. On one side of the rotatable member 4, a
tip end 5a of the proximal portion 5 is pivotally supported by the
bearing recess 8 via a bush 22, and on the other side there of, the
extending portion 6 is pivotally supported by bearing openings 9a
and 14a in the center of the partition wall and the flanged bush
14, respectively.
[0036] A seal is provided between the extending portion 6 and the
bearing opening 9a in the center of the partition wall 9 via a
sealing member 12 such as an O-ring mounted on the extending
portion 6, and another seal is provided between the outer
circumferential surface of the partition wall 9 and the inner
circumferential surface of the casing 2 via a sealing member 13
such as an O-ring mounted on the partition wall 9. By the flanged
bush 14 and the sealing members 12 and 13 interposed between the
partition wall 9 and the end cap 10, the viscous fluid 7 is
prevented from leaking from the interior of the casing 2.
[0037] On an outer circumferential surface 5b of the proximal
portion 5 of the rotatable member 4, a ridge member 15 is provided
to extend axially along and project radially outwardly from the
outer circumferential surface. The ridge member 15 is made up of a
ridge Protrusion 16 projecting from the outer circumferential
surface 5b of the proximal portion 5 and a substantially U-shaped
movable valve 17 mounted detachably so as to straddle the ridge
protrusion 16. The ridge protrusion 16 is formed with a cut-away
groove 18 constituting one of fluid passages, and one hanging wall
17a of both hanging walls 17a and 17b of the movable valve 17 on
the opposite sides of the ridge protrusion 16 is also formed with a
cut-away groove 19 constituting the fluid passage. A distance
between both of the hanging walls 17a and 17b of the movable valve
17 is larger than the width in the direction of rotation of the
ridge protrusion 16, and the ridge protrusion 16 is fitted to the
movable valve 17 so as to be loose in the direction of
rotation.
[0038] On rotating the rotatable member 4, the outer end face of
the movable valve 17 straddling the ridge protrusion 16 is in
sliding contact with the inner circumferential surface of the
chamber 3. Also, one end in the axial direction of the movable
valve 17 and the ridge protrusion 16 is in sliding contact with the
inner wall face of the partition wall 9, and the other end in the
axial direction thereof is in sliding contact with the inner wall
face of the closing end 2a of the casing 2.
[0039] A spacer 20 is mounted on the land 11 between the land 11
and the outer circumferential surface 5b of the proximal portion 5
of the rotatable member 4 so as to cover the side faces 11a and 11b
along the axial direction of the land 11 and an inner end face 11c
in the radial direction. The spacer 20 covering the side faces 11a
and 11b of the land 11 has a length L in the radial direction.
[0040] As the material for the spacer 20, plastic, rubber-like
material, metal or a combination thereof is preferably used.
[0041] As shown in FIG. 3, by the cooperation of the ridge member
15 and the land 11, the interior of the chamber 3 is divided into a
compression compartment 3a and a decompression compartment 3b so
that the compression and decompression compartments 3a, 3b are
variable complementarily to each other in response to said relative
rotation of the rotatable member 4 and casing 2. The compression
compartment 3a is located on the front side of the ridge protrusion
16 in a chamber 3 when the proximal portion 5 of the rotatable
member 4 is rotated in the direction such that the ridge protrusion
16 comes into contact with the hanging wall 17b without any fluid
passage of the movable valve 17 (in the clockwise rotating
direction in the drawing), and the decompression compartmentis is
located on the rear side of the ridge protrusion 16 in a chamber
3.
[0042] The following will be a description of the operation of the
rotary damper in accordance with the above-described first
embodiment.
[0043] Referring to FIG. 2, when the proximal portion 5 of the
rotatable member 4 is rotated in a first direction (in the
clockwise direction in FIG. 2) in the chamber 3 of the casing 2,
the ridge protrusion 16 moves between both of the hanging walls of
the movable valve 17 in the direction of rotation, so that a first
side face of the ridge protrusion 16 is pressed against the opposed
hanging wall 17b of the movable valve 17. At this time, the
cut-away groove 18 in the ridge protrusion 16 is closed by the
hanging wall 17b of the movable valve 17.
[0044] FIG. 2 shows a state in which the rotatable member 4 stands
still. This state corresponds to (i) of the torque curve shown in
FIG. 6 because no torque is produced in this state. In the torque
curve shown in FIG. 6, the abscissa X represents the angle of
rotation of the ridge member 15 from the position shown in FIG. 2
on an arbitrary scale, and the ordinate Y represents produced
torque on an arbitrary scale.
[0045] In FIG. 2, the rotatable member 4 is further rotated in the
clockwise direction in the drawing, and is rotated to a position
corresponding to about a half of the angle of full rotation, by
which the state shown in FIG. 3 is established. In this state, the
fluid pressure in the compression compartment 3a is increased, and
the increased fluid pressure acts on the spacer 20. The side face
11b on the side of the compression compartment 3a of the land 11
forms a transverse face which is disposed transversely with respect
to the rotational direction of said rotatable member 4. The spacer
20 has a body portion 20c positioned between the land 11 and the
proximal portion 5 of the rotatable member 4, and extension
portions 20d, 20e extending from the body portion 20c along the
side face 11a, 11b of the land 11, respectively. The extension
portion 20e close to the compression compartment 3a along the side
face 11b of the land 11 has an end face confronting the inner
circumferential surface of the chamber 3 to keep a gap 23
therebetween. In the state shown in FIG. 3, the high fluid pressure
acts on the gap 23, by which the spacer 20 is pressed against the
outer circumferential surface 5b of the proximal portion 5 and the
side face 11b of the land 11 in such a manner as to float slightly
from the inner end face 11c of the land 11. As a result, the
pressure in the compression compartment 3a can be kept high, so
that the produced torque can be kept high.
[0046] The gap may be formed between the extension portion 20d of
the spacer 20 along the side face 11a of the land 11 and the inner
circumferential surface of the chamber 3, as shown in FIG. 2.
[0047] The state shown in FIG. 3 corresponds to (ii) of the torque
curve shown in FIG. 6. The produced torque increases suddenly from
the state shown in FIG. 2, and reaches a value close to the maximum
torque in the state shown in FIG. 3.
[0048] In FIG. 3, the rotatable member 4 is further rotated in the
clockwise direction in the drawing. FIG. 4 shows a state just
before the hanging wall 17b of the movable valve 17 comes into
contact with one side face of the spacer 20 and thus the rotation
stops. During the time when the state changes from the state shown
in FIG. 3 to that shown in FIG. 4, the fluid pressure in the
compression compartment 3a further increases. Therefore, by the
action of the high fluid pressure on the spacer 20, as same manner
as shown in FIG. 3, the spacer 20 is brought more firmly into
contact with the outer circumferential surface 5b of the proximal
portion 5 and the side face 11b of the land 11 in such a manner as
to float further from the inner end face 11c of the land 11.
Thereby, the pressure in the compression compartment 3a can be kept
higher, with the result that the produced torque can be kept high
reliably.
[0049] The state shown in FIG. 4 corresponds to (iii) of the torque
curve shown in FIG. 6, showing the substantially maximum torque
produced . The state from (ii) to (iii) indicates the higher torque
region in which the produced torque increases slightly.
[0050] As described above, even if a spacer 20 portion that is in
contact with the outer circumferential surface 5b of the proximal
portion 5 of the rotatable member 4 is worn by the long-term use of
the rotary damper, in the rotation region in which high torque is
required for the rotatable member 4, the spacer 20 is pressed
against the outer circumferential surface 5b of the proximal
portion 5 and the side face 11b of the land 11 by the high fluid
pressure built up in the compression compartment 3a, so that the
produced torque can be prevented from decreasing.
[0051] FIG. 7 shows a torque curve in the case where the spacer is
removed from the rotary damper in accordance with the first
embodiment. The symbols in FIG. 7 are the same as those in FIG. 6.
In FIG. 7, the maximum torque is produced in the vicinity of (ii),
and in the region from (ii) to (iii), the produced torque decreases
gradually. The reason for this is that the rotatable member 4 is
rotated eccentrically by the increase in fluid pressure in the
compression compartment 3a, so that a clearance between the outer
circumferential surface 5b of the proximal portion 5 and the land
11 increases. As a result, the bypath flow of the viscous fluid 7
through the increased clearance increases, which causes the torque
to decreases . Thus, if no spacer is used, a desired high torque
cannot be obtained.
[0052] Next, when the rotatable member 4 is further rotated in the
clockwise direction in FIG. 4 from the state shown in FIG. 4, the
hanging wall 17b of the movable valve 17 comes into contact with
one side face of the spacer 20 and thus the rotation stops. When
the rotatable member 4 is rotated reversely in a second direction
(in the counterclockwise direction) from the stop state, the ridge
protrusion 16 moves between both of the hanging walls of the
movable valve 17 in the counterclockwise direction in the drawing,
so that a second side face of the ridge protrusion 16 is pressed
against the opposed hanging wall 17a formed with the cut-away
groove 19. Further, the rotatable member 4 is rotated
counterclockwise to a position corresponding to about a half of the
angle of full rotation, by which the state shown in FIG. 5 is
established. When the rotatable member 4 is rotated further in the
same direction, the hanging wall 17a of the movable valve 17 comes
into contact with the other side face of the spacer 20 and thus the
rotation stops, by which the state returns to the state shown in
FIG. 2.
[0053] During the time when the rotatable member 4 is rotated
counterclockwise as described above, the cut-away groove 18 in the
ridge protrusion 16 communicates with the cut-away groove 19 in the
hanging wall 1a and is opened. Therefore, the viscous fluid 7 moves
smoothly from the compression compartment 3b to the decompression
compartment 3a, so that the rotatable member 4 rotates
substantially without resistance.
[0054] In the torque curve for the counterclockwise rotation of the
rotatable member 4, the produced torque is zero at (iv) where the
rotatable member 4 stands still, and torque is scarcely produced
during the time when the state changes from (iv) to (i) through (v)
corresponding to FIG. 5 because the viscous fluid 7 moves smoothly
from the compression compartment 3b to the decompression
compartment 3a.
[0055] Although an example in which a pair of the ridge member 15
and the land 11 is used has been described in this embodiment, the
configuration may be such that a plurality of lands are provided on
the inner circumferential surface of the chamber 3 at equal
intervals in the circumferential direction to divide the chamber 3,
and one ridge member is accommodated in each of the divided
chamber. However, since eccentric wear occurs remarkably in the
case of what we call a one-blade rotary damper having one ridge
member 15, the action of such a spacer 20 achieves a pronounced
effect especially for a rotary damper using a pair of ridge member
and land.
[0056] The ridge member is not limited to the type shown in this
embodiment, and any ridge member may be used if it has a
construction such that a fluid passage for causing the compression
compartment and the decompression compartment to communicate with
each other can be formed. Further, the construction may be such
that he ridge protrusion and the movable valve are constructed s
that the fluid passages are not formed, and a fluid passage for
causing the compression compartment to communicate with the
decompression compartment is provided in the inside face of the
partition wall or in the inside face at the end of the casing.
[0057] As the material for the sparer 20, a rubber-like material
may be used to enhance the property of close contact with the outer
circumferential surface 5b of the proximal portion 5 of the
rotatable member 4, or, for example, a fluorine-containing plastic
having low friction may be used to decrease friction between the
outer circumferential surface 5b of the proximal portion 5 and the
spacer 20. Alternatively, a metal with high wear resistance may be
used.
[0058] A first modification of the above-described first embodiment
will be described with reference to FIGS. 10 and 11, except for the
same elements as those in the first embodiment. FIGS. 10 and 11 are
transverse sectional views of a rotary damper of this modification.
FIG. 10 shows the state corresponding to the state shown in FIG. 5
in the first embodiment, and FIG. 11 shows the state corresponding
to the state shown in FIG. 4. In FIGS. 10 and 11, the same
reference numerals are applied to the same elements as those in the
first embodiment.
[0059] In the rotary damper 101 of this modification, the casing
102 is of a substantially cylindrical shape, and the land 111 is
provided by forming a groove of an acute triangle shape in cross
section along the axial direction on the outer circumferential
surface of the chamber 103. An angle formed by the meeting of the
side faces 111a and 111b of the land 111 extending in an inward
direction of the casing 102 is about 15 degrees, a land with a
small angle being formed.
[0060] The upper face of the space 120 has a shape substantially
complementary to the outer circumferential surface of the proximal
portion 105. In the lower face of the spacer 120, a concave portion
120a engaging with the upper part of the land 111 is provided in a
substantially central portion in the circumferential direction. The
side face 111b on the side of the compression compartment 103a of
the land 111 forms a transverse face which is disposed transversely
with respect to the rotational direction of said rotatable member
104. The spacer 120 has extension portions 120d, 120e along the
side face 111a, 111b of the land 111, respectively. The extension
portion 120e close to the compression compartment 103a along the
side face 111b has an end face confronting the inner
circumferential surface of the chamber 103 to keep a gap 123
therebetween. As shown FIG. 10, the gap may be formed between the
extension portion 120d of the spacer 120 along the side face 111a
of the land 111 and the inner circumferential surface of the
chamber 103.
[0061] As shown in FIG. 10, when the rotary damper is assembled,
the spacer 120 is mounted on the land 111 in such a manner that the
upper part of the land 111 fits into the concave portion 120a.
[0062] In the state shown in FIG. 10 (during the time when the
rotatable member 104 is rotating counterclockwise in the drawing),
the viscous fluid 197 moves smoothly from the compression
compartment 103b to the decompression compartment 103a, so that
torque is scarcely produced. Therefore, the rotatable member 104
rotates substantially without resistance.
[0063] In the state shown in FIG. 11, the fluid pressure in the
compression compartment 103a exhibits the maximum value. When such
a high fluid pressure acts on the spacer 120, the high fluid
pressure is applied to the gap 123 formed between the spacer 120
and the inner circumferential surface of the chamber 103. As a
result, the upper face of the spacer 120 comes to be pressed
against close contact with the outer circumferential surface 105b
of the proximal portion 105 and the side face on the compression
compartment side of the concave portion 120a of the spacer 120
comes to be pressed against the side face 111b on the compression
compartment side of the land 111 in such a manner that the spacer
120 floats slightly toward the inside along the side faces 111a and
111b of the land 111. Thereby, the pressure in the compression
compartment 103a can be kept high, with the result that the
produced torque can be kept high reliably.
[0064] Next, a second modification of the above-described first
embodiment will be described on the basis of FIGS. 12A and 12B,
except for the same elements as those in the first embodiment.
[0065] As shown in FIG. 12A, in this modification, an angle made by
the side faces 211a and 211b in the case where the side faces 211a
and 211b of the land 1 are extended to the inside of the casing is
large. The side face 211b on the side of the compression
compartment 203a of the land 211 forms a transverse face which is
disposed transversely with respect to the rotational direction of
said rotatable member 204. The spacer 220 has extension portions
220d, 220e along the side face 211a, 211b of the land 211,
respectively. The extension portion 220e closed to the compression
compartment 203a has an end face confronting the inner
circumferential of the chamber 203. No gap is formed between the
end face of the portion 220e and the inner circumferential of the
chamber 203 so that the end face of the portion 220e is in contact
with the inner circumferential surface of the chamber 203. AS shown
in FIG. 12A, no gap may be formed between the end face of the
portion 220d and the inner circumferential of the chamber 203.
[0066] As shown in FIG. 12B, the fluid pressure P in the
compression compartment 203a acts perpendicularly on a side face
220b on the compression compartment 203a side of the spacer 220.
This fluid pressure P also acts on the side face 211b on the
compression compartment 203a side of the land 211. The fluid
pressure P acting on the side face 211b on the compression
compartment 203a side of the land 211 is divided into a component
pressure P.sub.1 in the direction perpendicular to the side wall
211b and a component pressure P.sub.2 in the direction parallel
thereto. By the component pressure P.sub.2 the spacer 220 is moved
upward along the side face 211b of the land 211. Therefore, even if
a gap is not formed between the end face of the portion on the
compression compartment 203a of the spacer 220 and the inner
circumferential surface of the chamber 203, the spacer can be
pressed reliably against the outer circumferential surface 205b of
the proximal portion 205 and side face 211b of the land 211 by the
pressure of the compression compartment 3a acting on the spacer
side face 220b in such a manner that t he spacer 220 floats
slightly from the inner end face 211c of the land 211.
[0067] Next, a third modification of the above-described first
embodiment will be described with reference to FIGS. 14A and 14B,
except for the same elements as those in the first embodiment.
[0068] As shown in FIG. 14A, in this modification, the side face
311b on the side of the compression compartment 303a of the land
311 forms a transverse face which is disposed transversely with
respect to the rotational direction of said rotatable member 304.
The spacer 320 has extension portions 320d, 320e along the side
face 311a, 311b of the land 311, respectively. The extension
portion 320e colosed to the compression compartment 303a has an end
face confronting the inner circumferential of the chamber 303. No
gap is formed between the end face of the portion 320e and the
inner circumferential of the chamber 303 so that the end face of
the portion 320e is in contact with the inner circumferential
surface of the chamber 303. AS shown FIG. 14A, no gap may be formed
between the end face of the portion 320d of the spacer 320 along
the side face 311a of the land 311 and the inner circumferential of
the chamber 303. In this modification, although an angle made by
the side faces 311a and 311b in the case where the side faces 311a
and 311b of the land 311 are extended to the inside of the casing
is relative small, extended lines of the side faces 320a and 320b
of the spacer 320 are tapered toward the outside of the casing.
[0069] As shown in FIG. 14B, the fluid pressure P in the
compression compartment 303a acts perpendicularly on the side face
320b on the compression compartment 303a side of the spacer 320.
This fluid pressure P also acts on the side face 31b on the
compression compartment 303a side of the land 311. The fluid
pressure P acting on the side face 311b on the compression
compartment 303a side of the land 311 is divided into a component
pressure P, in the direction perpendicular to the side wall 311b
and a component pressure P.sub.2 in the direction parallel thereto.
By the component pressure P.sub.2 the spacer 20 is moved upward
along the side face 311b of the land 311. Therefore, even if a gap
is not formed between the end face of the portion on the side of
the compression compartment 303a of the spacer 20 and the inner
circumferential surface of the chamber 303, the spacer 320 can be
pressed reliably against the outer circumferential surface 305b of
the proximal portion 305 and the side face 311b of the land 311 by
the pressure of the compression compartment 3a acting on the spacer
side face 320b in such a manner that the spacer 20 floats slightly
from the inner end face 311c of the land 311.
[0070] Next, a second embodiment of a rotary damper in accordance
with the present invention will be described with reference to
FIGS. 8 and 9, except for the same elements as those in the first
embodiment. FIGS. 8 and 9 are transverse sectional views of a
rotary damper in accordance with the second embodiment. FIG. 8
shows the state corresponding to the state shown in FIG. 5 in the
first embodiment, and FIG. 9 shows the state corresponding to the
state shown in FIG. 4. In FIGS. 8 and 9, the similar reference
numerals are applied to the same elements as those in the first
embodiment.
[0071] In the rotary damper 401 of the second embodiment, the
casing 402 has a substantially semicylindrical shape, and the land
411 is provided by bending about a half of the outer
circumferential surface of the chamber 403. Both of side faces 411a
and 411b of the land 411 extend in the radial direction of the
casing 402, and both of side faces are directed to the center O,
and an angle made by the side faces is about 150 degrees, a land
with a large angle being formed. An inward protrusion 421 is formed
along the axial direction in the central portion in the
Circumferential direction of the inner end face 411c of the land
411. The side faces 421a and 421b of the inward protrusion 421
extend in the radial direction of the casing 2, and the protrusion
width is narrower toward the inside.
[0072] The upper face of the space 420 has a shape substantially
complementary to the outer circumferential surface of the proximal
portion 405. The lower face of the spacer 420 has a shape
substantially complementary to the inner end face 411c of the land
411, and is provided with the concave portion 420a engaging with
the inward protrusion 421 of the land 411 in a substantially
central portion in the circumferential direction. The side face
421b on the side of the compression compartment 403a of the inward
protrusion 421 forms the transverse face which is disposed
transversely with respect to the rotational direction of the
rotatable member 404. The spacer 420 has a center portion 420c
positioned between the proximal portion 405 of the rotatable member
404 and the protrusion 421, and side portions 420d, 420e extending
in opposite directions from the center portion 420c along the inner
end face 411c of the land 411. Each of the side portion 420d, 420e
has an end face confronting the inner end face 411c of the land
411. The end face of the side portion 420e closed to the
compression compartment 403a has a portion at the extremity in the
circumferential direction close to the compression compartment 403a
spaced apart from the inner end face 411c of the land 411 to keep a
gap 423 therebetween. The gap 423 may be formed between the end
face of the side portion 420d of the spacer 420 and the inner end
face 411c of the land 411. When the rotary damper is assembled, the
spacer 420 is mounted on the land 411 in such a manner that the
inward protrusion 421 fits into the concave portion 20a as shown in
FIG. 8.
[0073] The construction for engaging the spacer 420 with the land
411 may be such that an outward protrusion having a width being
narrower toward the outside is provided on the lower face of the
spacer 420, and an engaging concave portion having a shape
complementary to the outward protrusion is formed in the inner end
face 411c of the land 411.
[0074] The state shown in FIG. 8 is a state in which the rotatable
member 404 is rotating counterclockwise in the drawing. In this
state, the viscous fluid 407 moves smoothly from the compression
compartment 403b to the decompression compartment 403a, so that
torque is scarcely produced. Therefore, the rotatable member 404
rotates substantially without resistance.
[0075] In the state shown in FIG. 9, the fluid pressure in the
compression compartment 403a exhibits the maximum value. When such
a high fluid pressure acts on the spacer 420, the high fluid
pressure is applied to the gap 423 formed between the end face of
the portion of spacer 420 and the inner end face 411c of the land
411. As a result, the upper face of the spacer 420 comes to be
pressed against the outer circumferential surface 405b of the
proximal portion 405, and the side face on the side of the
compression compartment 403a of the concave portion 420a of the
spacer 20 comes to be pressed against the side face 421b on the
compression compartment side of the inward protrusion 421 in such a
manner that the spacer 420 floats slightly toward the, inside along
the side faces 421a and 421b of the inward protrusion 421 of the
land 411. Thereby, the pressure in the compression compartment 3a
can be kept high, with the result I,hat the produced torque can be
kept high reliably.
[0076] Next, a modification of the above-described second
embodiment will be described with reference to FIGS. 13A and 13B,
except for the same elements as those in the second embodiment.
[0077] As shown in FIG. 13A, the side face 521b on the side of the
compression compartment 503a of the inward protrusion 521 forms the
transverse face which is disposed transversely with respect to the
rotational dire on of the rotatable member 504. The spacer 520 has
a center portion 520c positioned between the proximal portion 505
of the rotatable member 504 and the protrusion 521, and side
portions 520d, 520e extending in opposite directions from the
center portion 520c along the inner end face 511c of the land 511.
Each of the side portion 520d, 520e has an end face confronting the
inner end face 51lc of the land 511. No gap is formed between the
end face of the portion 520e closed to the compression compartment
503a and the inner end face 511c of the land 511 so that the end
face of the portion 520e is in contact with the inner end face 511c
of the land 511. As shown in FIG. 13A, no gap may be formed between
the end face of the portion 520d of the spacer 520 and the inner
end face 511c of the land 511. In this modification, extended lines
of the side faces 520a and 520b of the spacer 520 are tapered
toward the outside of the casing 502.
[0078] As shown in FIG. 13B, the fluid pressure P in the
compression compartment 503a acts perpendicularly on the side face
520b on the compression compartment 503a side of the spacer 520.
This fluid pressure P also acts on the side face 521b on the
compression compartment side of the inward protrusion 521 of the
land 511. The fluid pressure P acting on the side face 521b of the
inward protrusion 521 is divided into a component pressure P, in
the direction perpendicular to the side face 521b and a component
pressure P.sub.2 in the direction parallel thereto. By the
component pressure P.sub.2 , the spacer 520 is moved upward along
the side face 521b on the compression compartment 503a side of the
inward protrusion 21. Therefore, even if a gap is not formed
between the end face of the portion on the compression compartment
side of the spacer 520 and the inner end face 511c of the land 511,
the pacer can be pressed reliably against the outer circumferential
surface 505b of the proximal portion 505 and the side face 521b of
the inward protrusion 521 by the pressure of the compression
compartment 503a acting on the spacer side face 520b in such a
manner that the spacer 520 floats slightly from the inner end face
511c of the land 511.
[0079] In the present invention as claimed in claim 1, the rotary
damper is constructed so that the land has a transverse face
transversely with respect to rotational direction of the rotatable
member, and a spacer is interposed between the land and the
proximal portion of the rotatable member and adapted to be pressed
against the outer circumferential surface of the proximal portion
of the rotatable member and the transverse face of the land by the
pressure built up in the compression compartment in response to the
roration of the rotatable member.
[0080] Thereby, in the high torque region, the spacer is brought
into close contact with the outer circumferential surface of the
proximal portion of the rotatable member and the transverse face of
the land by the pressure on the compression compartment side. The
gap between the outer circumferential surface of the proximal
portion and the inner end face of the land can be closed reliably
at the time when a high torque is produced, so that a decrease in
torque caused by the eccentric rotation of the proximal portion can
be prevented. Also, even if a spacer portion on the outer
circumferential surface side of the proximal portion of the
rotatable member is worn by the long-term use of the rotary damper,
a decrease in torque in the high rotation torque region can be
prevented.
[0081] In the present invention as claimed in claim 2, the spacer
is provided so as to cover the inner end face of the land and the
side face on the side of the compression compartment of the land,
and in the present invention defined in claim 4, the spacer is
mounted on the inner end face of the land while engaging with the
inward protrusion provided on the inner end face of the land.
Therefore, the spacer does not come off from the land by the
pressure on the compression compartment side, and can be disposed
reliably on the land.
[0082] In the present invention as claimed in claim 3, the spacer
has a portion along the side face of the land and such portion has
a end face confronting the inner circumferential surface of the
chamber to keep therebetween. Therefore, in the high torque region,
the spacer is pressed against the outer circumferential surface of
the proximal portion of the rotatable member and the side face on
the compression compartment side of the land by the pressure on the
compression compartment side in such a manner as to float from the
inner end face of the land, so that the gap between the outer
circumferential surface of the proximal portion and the inner end
face of the land can be closed reliably, whereby a decrease in
torque can be prevented.
[0083] In the present invention as claimed in claim 5, the spacer
has a portion on the side of the compression compartment such
portion has an end face confronting the inner end face of the land
to keep a gap therebetween. Therefore, the spacer is pressed
against the outer circumferential surface of the proximal portion
of the rotatable member and the side face on the compression
compartment side of the inward protrusion in such a manner as to
float from the inner end face of the land, so that the gap between
the outer circumferential surface of the proximal portion and the
inner end face of the land can be closed reliably, whereby a
decrease in torque can be prevented.
[0084] As is claimed in claim 6, the spacer is formed of a plastic
material, by which friction between the outer circumferential
surface of the proximal portion and the spacer can be decreased, or
the spacer is formed of a rubber-like material using elasticity, by
which the property of close contact with the outer circumferential
surface e of the proximal portion can be enhanced. Further, the
spacer is formed of a metal with high wear resistance, by which the
strength and durability of the spacer can be increased. In
particular, as is claimed in claim 7, the plastic material is a
fluorine-containing plastic material, which achieves an effect that
friction between the outer circumferential surface of the proximal
portion of the rotatable member and the spacer can further be
decreased.
* * * * *