U.S. patent application number 09/767858 was filed with the patent office on 2001-08-30 for clutch having reduced noise level and motor including such clutch.
Invention is credited to Torii, Katsuhiko, Yamamoto, Hiroaki.
Application Number | 20010017496 09/767858 |
Document ID | / |
Family ID | 18551084 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010017496 |
Kind Code |
A1 |
Torii, Katsuhiko ; et
al. |
August 30, 2001 |
Clutch having reduced noise level and motor including such
clutch
Abstract
A clutch includes an outer ring, a driving-side rotator, a
driven-side rotator and rolling elements. Each rolling element is
located between an inner circumferential surface of the ring and a
corresponding control surface of the driven-side rotator and has a
diameter shorter than a distance between a circumferential center
portion of the control surface and the inner circumferential
surface of the ring but longer than a distance between each of
opposing circumferential end portions of the control surface and
the inner circumferential surface of the ring. The center portion
is located radially outward of a straight line that connects the
end portions. Each intermediate portion positioned between the
center portion and the end portion is arcuately bulged beyond a
straight line that connects the center portion and the end
portion.
Inventors: |
Torii, Katsuhiko;
(Hamamatsu-city, JP) ; Yamamoto, Hiroaki;
(Kosai-city, JP) |
Correspondence
Address: |
LAW OFFICE OF DAVID G POSZ
2000 L STREET, N.W.
SUITE 200
WASHINGTON
DC
20036
US
|
Family ID: |
18551084 |
Appl. No.: |
09/767858 |
Filed: |
January 24, 2001 |
Current U.S.
Class: |
310/77 ;
192/223.2 |
Current CPC
Class: |
F16D 41/105 20130101;
E05F 15/697 20150115; E05Y 2900/55 20130101; E05F 11/505 20130101;
F16D 41/064 20130101 |
Class at
Publication: |
310/77 ;
192/223.2 |
International
Class: |
B60K 041/26 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2000 |
JP |
2000-25193 |
Claims
What is claimed is:
1. A clutch comprising: an outer ring that is non-rotatably secured
and has an inner circumferential surface; a driving-side rotator
that is connected to a drive source and is rotatably received
within said outer ring, wherein said driving-side rotator includes
an engaging slot that has an opening at its outer circumferential
side; a driven-side rotator that is connected to a load and is
rotatably received within said outer ring, wherein said driven-side
rotator includes an engaging projection, which engages said
engaging slot to limit relative rotation of said driving-side
rotator within a predetermined range and which has a control
surface opposing said inner circumferential surface of said outer
ring at its outer circumferential wall surface; and a rolling
element that is located between said inner circumferential surface
of said outer ring and said control surface in said opening and
that has an outer diameter shorter than a distance between a
circumferential center portion of said control surface and said
inner circumferential surface of said outer ring but longer than a
distance between each of opposing circumferential end portions of
said control surface and said inner circumferential surface of said
outer ring, wherein said circumferential center portion of said
control surface is located radially outward of a straight line that
connects said opposing circumferential end portions of said control
surface.
2. A clutch according to claim 1, wherein each intermediate portion
positioned between said circumferential center portion and a
respective one of said circumferential end portions is arcuately
bulged in a radially outward direction beyond a corresponding
straight line that connects said circumferential center portion and
a corresponding one of said circumferential end portions.
3. A clutch according to claim 2, wherein said control surface is
entirely arcuately bulged, wherein said arcuately bulged control
surface has a radius of curvature greater than that of a rotational
trajectory of said circumferential center portion of said control
surface about a rotational axis of said driven-side rotator.
4. A clutch according to claim 2, wherein said circumferential
center portion of said control surface is flat.
5. A clutch according to claim 2, wherein said circumferential
center portion of said control surface is arcuate, wherein said
arcuate circumferential center portion is coaxial with said inner
circumferential surface of said outer ring.
6. A clutch according to claim 2, wherein each said circumferential
end portion of said control surface of said engaging projection has
a retainer portion that prevents said rolling element to move out
from a space between said inner circumferential surface of said
outer ring and said control surface.
7. A clutch according to claim 2, wherein: when said driving-side
rotator is rotated by a rotational force transmitted from said
drive source, an inner sidewall surface of said opening urges said
rolling element to substantially position said rolling element in
said circumferential center portion of said control surface and
transmits said rotational force of said driving-side rotator from
said engaging slot to said driven-side rotator through said
engaging projection; and when said driven-side rotator is rotated
by a rotational force transmitted from said load, said control
surface urges said rolling element to clamp said rolling element
between said inner circumferential surface of said outer ring and
said control surface to prevent rotation of said driven-side
rotator.
8. A clutch according to claim 2, wherein said outer diameter of
said rolling element is equal to a distance between said each
intermediate portion of said control surface and said inner
circumferential surface of said outer ring, so that when said
driven-side rotator is rotated by said rotational force transmitted
from said load, said rolling element is clamped between either one
of said intermediate portions of said control surface and said
inner circumferential surface of said outer ring.
9. A clutch according to claim 8, wherein said rolling element
makes line contact with said inner circumferential surface of said
outer ring and also with said intermediate portion of said control
surface when said rolling element is clamped between said
intermediate portion of said control surface and said inner
circumferential surface of said outer ring.
10. A motor comprising a clutch according to claim 2.
11. A clutch comprising: an outer ring that is non-rotatably
secured and has an inner circumferential surface; a driving-side
rotator that is connected to a drive source and is rotatably
received within said outer ring; a driven-side rotator that is
connected to a load and is rotatably received within said outer
ring, wherein said driven-side rotator is connected to said
driving-side rotator in a manner allowing relative rotation of said
driven-side rotator within a predetermined range in a rotational
direction and has a control surface opposing said inner
circumferential surface of said outer ring at its outer
circumferential surface; and a rolling element located between said
control surface of said driven-side rotator and said inner
circumferential surface of said outer ring, wherein said rolling
element is smaller than a distance between a circumferential center
portion of said control surface and said inner circumferential
surface of said outer ring but larger than a distance between each
of opposing circumferential end portions of said control surface
and said inner circumferential surface of said outer ring and is
positionable between a clamped position where said rolling element
is clamped between said control surface of said driven-side rotator
and said inner circumferential surface of said outer ring and a
non-clamped position where said rolling element is not clamped
between said control surface of said driven-side rotator and said
inner circumferential surface of said outer ring, wherein each
intermediate portion positioned between said circumferential center
portion and a respective one of said circumferential end portions
is arcuately bulged in a radially outward direction beyond a
corresponding straight line that connects said circumferential
center portion and a corresponding one of said circumferential end
portions.
12. A clutch according to claim 11, wherein said circumferential
center portion of said control surface is located radially outward
of a straight line that connects said opposing circumferential end
portions of said control surface.
13. A clutch according to claim 12, wherein: a plurality of rolling
elements is provided around a rotational axis of said driving-side
rotator; and wherein each of said rolling elements is positioned in
said clamped position when said driven-side rotator is rotated in
either a first or second rotational direction.
14. A clutch according to claim 12, wherein said control surface is
provided for each of said rolling elements.
15. A clutch according to claim 12, wherein each said rolling
element is made of resin material.
16. A clutch according to claim 12, wherein said outer diameter of
said rolling element is equal to a distance between said each
intermediate portion of said control surface and said inner
circumferential surface of said outer ring.
17. A clutch according to claim 16, wherein said circumferential
center portion of said control surface is flat.
18. A clutch according to claim 16, wherein: said circumferential
center portion of said control surface is arcuate, wherein said
arcuate circumferential center portion is coaxial with said inner
circumferential surface of said outer ring.
19. A clutch according to claim 12, wherein: when said driving-side
rotator is rotated by a rotational force transmitted from said
drive source, said driving-side rotator causes said rolling element
to be positioned in said non-clamped position and to be rotated
along with said driving-side rotator, and said driving-side rotator
engages said driven-side rotator in said rotation direction to
transmit said rotational force of said driving-side rotator to said
driven-side rotator; and when said driven-side rotator is rotated
by a rotational force transmitted from said load, said rolling
element is positioned in said clamped position, and rotation of
said driven-side rotator is allowed or prevented while providing a
desired frictional force between said rolling element and said
inner circumferential surface of said outer ring.
20. A motor comprising a worm shaft, a rotatable shaft and a clutch
according to claim 12, wherein said clutch is arranged between said
worm shaft and said rotatable shaft.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2000-25193 filed Feb. 2,
2000.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to a clutch and,
more particularly, to a clutch that prevents transmission of a
rotational force from its driven side to its driving side and also
a motor having such a clutch.
[0003] PCT publication No. WO00/08349 published on Feb. 17, 2000
proposes a clutch that prevents transmission of a rotational force
from the driven side to the driving side.
[0004] This clutch includes an outer ring, a driving-side rotator,
a driven-side rotator and rolling elements. The driving-side
rotator is rotatably received within the outer ring and is
connected to a drive source. The driving-side rotator includes
engaging slots having an opening on its outer circumferential side
(inner circumferential side of the outer ring).
[0005] The driven-side rotator is rotatably received within the
outer ring and is connected to a load. The driven-side rotator has
engaging projections for rotatably engaging with the corresponding
engaging slot of the driving-side rotator. A control surface
opposing an inner circumferential surface of the outer ring is
provided on an outer circumferential surface of each engaging
projection.
[0006] Within the opening of each engaging slot, the corresponding
rolling element is positioned between the inner circumferential
surface of the outer ring and the control surface. The rolling
element has a diameter that is smaller than a distance between a
circumferential center portion of the control surface and the inner
circumferential surface of the outer ring but is longer than a
distance between each of opposing circumferential end portions of
the control surface and the inner circumferential surface of the
outer ring.
[0007] In this clutch, when the driving-side rotator is rotated,
each rolling element is urged by an inner wall surface of the
opening of the corresponding engaging slot and is substantially
positioned in the center portion of the control surface. The
rotational force of the driving-side rotator is conducted from each
engaging slot to the driven-side rotator via the corresponding
engaging projection.
[0008] When the driven-side rotator is rotated, each rolling
element is urged by the control surface against the inner
circumferential surface of the outer ring and is clamped between
the inner circumferential surface of the outer ring and the control
surface to prevent rotation of the driven-side rotator.
[0009] The control surface of the above-described clutch should be
formed such that a distance between the control surface and the
outer ring decreases from the circumferential center portion toward
the opposing circumferential end portions. In the above-described
clutch, the center portion of the control surface is located
radially inward (closer to the rotational center) of a straight
line connecting the opposing circumferential end portions, and part
of the control surface between the center portion and each one of
the circumferential end portions is flat. Alternatively, the entire
control surface may be in a single flat surface.
[0010] In the above-described clutch, it is difficult to make a
small radial gap between the rolling element and the opposing
circumferential center portion of the control surface as well as
between the rolling element and the opposing inner circumferential
surface of the outer ring. If these gaps are further reduced, a
slight movement of the rolling element out of the center portion
causes the rolling element to be clamped between the control
surface and the inner circumferential surface of the outer ring.
Furthermore, when the driving-side rotator is rotated, the rolling
element may not be accurately positioned in the center portion, so
that the rotation of the driving-side rotator may be prevented. On
the other hand, if these gaps are further increased, the rolling
element is allowed to move substantially in a radial direction when
the driving-side rotator is rotated. This radial movement of the
rolling element causes generation of noises.
[0011] Also, in the above-described clutch, when the rolling
element is urged by the circumferential end portion of the control
surface against the inner circumferential surface of the outer
ring, a radially outwardly directed force component of the urging
force exerted by the circumferential end portion cannot be
sufficiently increased. Thus, when the driven-side rotator is
rotated, the rolling element may not be clamped between the control
surface and the inner circumferential surface of the outer ring.
That is, the rolling element may move along the inner
circumferential surface of the outer ring.
SUMMARY OF THE INVENTION
[0012] Thus, it is an objective of the present invention to provide
a clutch having a reduced noise level as well as a motor having
such a clutch.
[0013] It is another objective of the present invention to provide
a clutch which is capable of preventing transmission of a
rotational force from its driven-side to its driving-side as well
as a motor having such a clutch.
[0014] To achieve the objective of the present invention, there is
provided a clutch including an outer ring, a driving-side rotator,
a driven-side rotator and a rolling element. The outer ring is
non-rotatably secured and has an inner circumferential surface. The
driving-side rotator is connected to a drive source and is
rotatably received within the outer ring. The driving-side rotator
includes an engaging slot that has an opening at its outer
circumferential side. The driven-side rotator is connected to a
load and is rotatably received within the outer ring. The
driven-side rotator includes an engaging projection, which engages
the engaging slot to limit relative rotation of the driving-side
rotator within a predetermined range and which has a control
surface opposing the inner circumferential surface of the outer
ring at its outer circumferential wall surface.
[0015] The rolling element is located between the inner
circumferential surface of the outer ring and the control surface
in the opening and that has a diameter shorter than a distance
between a circumferential center portion of the control surface and
the inner circumferential surface of the outer ring but longer than
a distance between each of opposing circumferential end portions of
the control surface and the inner circumferential surface of the
outer ring. Specifically, the circumferential center portion of the
control surface is located radially outward of a straight line that
connects the opposing circumferential end portions of the control
surface. Each intermediate portion positioned between the
circumferential center portion and a respective one of the
circumferential end portions is arcuately bulged in a radially
outward direction beyond a corresponding straight line that
connects the circumferential center portion and a corresponding one
of the circumferential end portions.
[0016] Furthermore, to achieve the objective of the present
invention, there is also provided a motor having the
above-described clutch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention, together with additional objects, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0018] FIG. 1 is an exploded perspective view of a motor according
to an embodiment of the present invention;
[0019] FIG. 2 is a schematic plan cross-sectional view of the motor
shown in FIG. 1;
[0020] FIG. 3 is an exploded perspective view of a clutch according
the embodiment;
[0021] FIG. 4 is a schematic partial longitudinal cross-sectional
view of the clutch according to the embodiment;
[0022] FIG. 5 is a partial perspective view of a support member of
the clutch according to the embodiment;
[0023] FIG. 6 is a schematic cross-sectional view of the clutch
according to the embodiment;
[0024] FIG. 7 is a partial schematic cross-sectional view of the
clutch according to the embodiment;
[0025] FIG. 8 is a schematic cross-sectional view of the clutch
according to the embodiment;
[0026] FIG. 9 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0027] FIG. 10 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0028] FIG. 11 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0029] FIG. 12 is a schematic side view of a power window system
according to the embodiment;
[0030] FIG. 13 is a partial cross-sectional view illustrating a
modification of the clutch;
[0031] FIG. 14 is another partial cross-sectional view illustrating
another modification of the clutch; and
[0032] FIG. 15 is another partial cross-sectional view illustrating
another modification of the clutch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033] One embodiment of the present invention will be described
with reference to a power window system shown in FIGS. 1 to 12.
[0034] As shown in FIG. 12, a motor 1 of the power window system is
secured to a vehicle door D. The motor 1 has a motor main body 2
and an output unit 3. The motor main body 2 rotates a gear 4a
secured to an output shaft 4 of the output unit 3 in a forward or
backward rotational direction. The gear 4a meshes with a gear G
provided on a window regulator R of an X-arm type. Thus, when the
gear 4a is rotated forward or backward, the window regulator R
moves a window glass W up and down, respectively.
[0035] As shown in FIGS. 1 and 2, a coupling portion 5a having a
generally D-shaped cross section is formed on a distal end of a
rotatable shaft 5 of the motor main body 2.
[0036] At the distal end of the motor main body 2 (rotatable shaft
5), a clutch 6 is provided. As shown in FIGS. 3 and 4, the clutch 6
includes a clutch housing 7, a driving-side rotator 8, a ball 9, a
driven-side rotator 10, a plurality (three in this instance) of
rolling elements 11 and a support member 12. The clutch housing 7
includes a cylindrical outer ring 7a and annular covers 7b, 7c that
extend radially inward from opposing circumferential edges of the
outer ring 7a, respectively. The driving-side rotator 8, the ball
9, the driven-side rotator 10, the rolling elements 11 and the
support member 12 are assembled and are housed within the clutch
housing 7 to constitute one functional unit (clutch 6).
[0037] The driving-side rotator 8 is made of resin material and
includes a shaft 8a and a disk body 8b having a diameter larger
than that of the shaft 8a. A base side (the left side of FIG. 4) of
disk body 8b of the driving-side rotator 8 slides and rotates along
an inner wall surface of the annular cover 7b of the clutch housing
7. A shaft center hole 8c extends through the driving-side rotator
8 along the rotational axis thereof. A coupling hole 8d having a
generally D-shape cross section is formed at a base side (the left
side of FIG. 4) of the shaft center hole 8c. As shown in FIG. 4,
the coupling hole 8d is exposed to the exterior of the clutch
housing 7 and is securely coupled wish the coupling portion 5a of
the rotatable shaft 5. Thus, when the rotatable shaft 5 of the
motor main body 2 is rotated, the rotational force of the rotatable
shaft 5 is transmitted to the driving-side rotator 8.
[0038] Furthermore, as shown in FIG. 3, a plurality (three in this
instance) of generally fan-shaped protrusions 13 are arranged at
the distal side (the right side of FIG. 4) of the disk body 8b. The
protrusions 13 are circumferentially spaced at equal angular
intervals and extend in an axial direction of the driving-side
rotator 8. In each protrusion 13, a coupling groove 13a extends
halfway from an inner circumferential surface of each protrusion 13
in a radially outward direction.
[0039] A cushion member 14 made of rubber material is securely
coupled to the coupling groove 13a of each protrusion 13. More
particularly, the cushion member 14 includes a relatively thin ring
14a and a plurality (three in this instance) of cushion segments
14b. The cushion segments 14b are spaced at equal angular intervals
around an outer circumference of the ring 14a. Each cushion segment
14b has a coupling projection 14c for engaging with the coupling
groove 13a on its outer circumferential side. Each coupling
projection 14c is coupled with the corresponding coupling groove
13a, and the ring 14a is secured to the disk body 8b.
[0040] As shown in FIG. 6, a circumferential width of each cushion
segment 14b is slightly longer than a circumferential width of an
inner circumferential surface of the corresponding protrusion 13. A
plurality (three in this instance) of engaging slots 15 are formed
at equal angular intervals. Each engaging slot 15 is defined
between one side surface (radially extending surface) 13b of one
protrusion 13 and an opposing side surface 13c of the next
protrusion 13 and also between one side surface 14d of one cushion
segment 14b and an opposing side surface 14e of the next cushion
segment 14b. These engaging slots 15 are communicated with each
other at center side. Recesses 16 (FIG. 3) that extend in an axial
direction are formed around the outer circumference of the disk
body 8b between the protrusions 13. The side surfaces 13b, 13c of
the protrusions 13 are slightly bulged in the circumferential
direction at their outer circumferential sides to define an opening
17 of each engaging slot 15.
[0041] The ball 9 is a spherical metal having an outer diameter
corresponding to an inner diameter of the shaft center hole 8c and
is received in the shaft center hole 8c from a distal end opening
(the right side of FIG. 4) of the shaft center hole 8c. While the
ball 9 is received in the shaft center hole 8c, part of the ball 9
protrudes from the shaft center hole 8c.
[0042] The driven-side rotator 10 has a disk body 10a and a
coupling body 10b that protrudes from the center of the disk body
10a toward its distal end (the right side of FIG. 4).
[0043] The disk body 10a abuts the ball 9 at its base side (the
left side of FIG. 4) and is surrounded by the protrusions 13
(cushion segments 14b) in a manner that allows rotation of the disk
body 10a. Furthermore, since the disk body 10a makes point contact
with the ball 9, the disk body 10a can rotate smoothly.
[0044] As shown in FIGS. 3 and 6, the disk body 10a has a plurality
(three in this instance) of generally fan-shaped engaging
projections 18. The engaging projections 18 extend radially outward
and are spaced at equal angular intervals. A circumferential width
of each engaging protrusion 18 is smaller than that of the
corresponding engaging slot 15, and the engaging protrusion 18 is
received in the corresponding engaging slot 15.
[0045] As shown in FIG. 6, a first cushion surface 18a opposing one
side surface (counter-clockwise side surface) 14d of the
corresponding cushion segment 14b is formed at a radially inward
region of a clockwise side surface of each engaging projection 18.
Furthermore, a first engaging surface 18b opposing one side surface
(counter-clockwise side surface) 13b of the corresponding
protrusion 13 is formed at a radially outward region of the
clockwise side surface of the engaging projection 18. The first
cushion surface 18a engages the one side surface 14d of the cushion
segment 14b when the driving-side rotator 8 is rotated to a
predetermined position in the counter-clockwise direction (the
direction of an arrow X) relative to the driven-side rotator 10.
Furthermore, the first engaging surface 18b engages the one side
surface 13b of the protrusion 13 when the driving-side rotator 8 is
rotated beyond the predetermined position in the counter-clockwise
direction (the direction of the arrow X). Since the cushion segment
14b is deformed in the circumferential direction, the driving-side
rotator 8 is allowed to rotate beyond the predetermined position in
the counterclockwise direction (the direction of the arrow X), as
shown in FIG. 8.
[0046] A second cushion surface 18c opposing the other side surface
(clockwise side surface) 14e of the corresponding cushion segment
14b is formed at a radially inward region of an counter-clockwise
side surface of each engaging projection 18. Furthermore, a second
engaging surface 18d opposing the other side surface (clockwise
side surface) 13c of the corresponding protrusion 13 is formed at a
radially outward region of the counter-clockwise side surface of
the engaging projection 18. The second cushion surface 18c engages
the other side surface 14e of the cushion segment 14b when the
driving-side rotator 8 is rotated to a predetermined position in
the clockwise direction (the direction of an arrow Y) relative to
the driven-side rotator 10. Furthermore, the second engaging
surface 18d engages the other side surface 13c of the protrusion 13
when the driving-side rotator 8 is rotated beyond the predetermined
position in the clockwise direction (the direction of the arrow Y).
Since the cushion segment 14b is deformed in the circumferential
direction, the driving-side rotator 8 is allowed to rotate beyond
the predetermined position in the clockwise direction (the
direction of the arrow Y), as shown in FIG. 9.
[0047] A control surface 19 is formed on an outer circumferential
surface of each engaging projection 18. In the present embodiment,
as shown in FIG. 7, the control surface 19 is entirely arcuately
bulged in a radially outward direction beyond a rotational
trajectory A of a circumferential center portion 19a about the
rotational axis of the driven-side rotator 10. A radius of
curvature of the arcuately bulged control surface 19 is larger than
that of the rotational trajectory A. Thus, in the control surface
19, the center portion 19a is located radially outward of a
straight line K that connects opposing circumferential end portions
19b and 19c of the control surface 19. Furthermore, in the control
surface 19, each intermediate portion 19d positioned between the
center portion 19a and a respective one of the end portions 19b,
19c is arcuately bulged in a radially outward direction beyond a
corresponding straight line J that connects the center portion 19a
and a corresponding one of the end portions 19b, 19c.
[0048] Each rolling element 11 is a generally cylindrical body made
of metal or resin material. The rolling element 11 is
circumferentially positioned between a first side surface 17a and a
second side surface 17b of the opening 17 and is radially
positioned between the control surface 19 of the engaging
projection 18 and an inner circumferential surface 7d of the outer
ring 7a of the clutch housing 7.
[0049] As shown in FIG. 7, a diameter B of the rolling element 11
is smaller than a distance C between the center portion 19a of the
control surface 19 and the inner circumferential surface 7d of the
outer ring 7a but is longer than a distance E between each of the
end portions 19b, 19c of the control surface 19 and the inner
circumferential surface 7d of the outer ring 7a. Furthermore, an
outer diameter B of the rolling element 11 is equal to a distance F
between each intermediate portion 19d and the inner circumferential
surface 7d of the outer ring 7a.
[0050] The support member 12 is made of resin material and includes
a ring plate 20 and three roller supports 21. The ring plate is
slidably received between the cover 7c of the clutch housing 7 and
the protrusions 13 of the driving-side rotator 8. As shown in FIG.
5, the roller supports 21 extend in the axial direction from the
ring plate 20 and are spaced at equal angular intervals.
[0051] Each roller support 21 includes a couple of retaining
pillars 21a and a connector 21b. The retaining pillars 21a extend
in the axial direction from the ring plate 20, and the connector
21b connects distal ends of the retaining pillars 21a together. In
the roller support 21, a distance between the retaining pillars 21a
is slightly longer than a diameter of the rolling element 11, and a
distance between the ring plate 20 and the connector 21b is
slightly longer than an axial length of the rolling element 11. The
rolling element 11 is rotatably supported between the two retaining
pillars 21a and also between the ring plate 20 and the connector
21b. Furthermore, the rolling element 11 is immovable in the
circumferential direction of the ring plate 20 but is moveable in
the radial direction of the ring plate 20.
[0052] In this embodiment, geometrical arrangements of the
above-described components 11, 13, 18 and 21 are as follows. That
is, as shown in FIG. 8, when the one side surface 13b of each
protrusion 13 engages the first engaging surface 18b of the
corresponding engaging projection 18, and the first side surface
17a of each opening 17 engages the corresponding roller support 21,
the corresponding rolling element 11 is positioned in the center
portion 19a of the control surface 19. Furthermore, as shown in
FIG. 9, when the other side surface 13c of each protrusion 13
engages the second engaging surface 18d of the corresponding
engaging projection 18, and the second side surface 17b of each
opening 17 engages the corresponding roller support 21, the
corresponding rolling element 11 is positioned in the center
portion 19a of the control surface 19.
[0053] As shown in FIG. 2, a worm housing 22a of the output unit 3
has a cylindrical protrusion 22b at its base side (the left side of
FIG. 2). An inner diameter of the cylindrical protrusion 22b
corresponds to an outer diameter of the clutch housing 7 of the
clutch 6. The clutch housing 7 is securely inserted into the
cylindrical protrusion 22b.
[0054] A worm shaft 23 is received within the worm housing 22a. At
the base side (the left side of FIGS. 2 and 4) of the worm shaft
23, there is formed a coupling hole 23a corresponding to the
coupling body 10b of the driven-side rotator 10. The coupling body
10b is inserted within and securely coupled to the coupling hole
23a to integrally rotate therewith.
[0055] A worm 23b of the worm shaft 23 is meshed with a worm wheel
24a of a rotatable coupler 24 that is rotatably supported within a
wheel housing 22c of the output unit 3. The rotatable coupler 24 is
connected to an output plate 26 via a motor protective rubber 25. A
base end of the output shaft 4 is non-rotatably secured to the
output plate 26.
[0056] Thus, when the worm shaft 23 is rotated, the rotational
force of the worm shaft 23 is transmitted to the output shaft 4 via
the rotatable coupler 24, the motor protective rubber 25 and the
output plate 26 to rotate the output shaft 4.
[0057] A plate cover 27 is secured to an opening of the wheel
housing 22c.
[0058] The power window system (clutch 6) having the
above-described construction operates as follows.
[0059] When the motor 2 is driven to rotate the rotatable shaft 5
in the counter-clockwise direction (the direction of the arrow X)
of FIG. 6, the driving-side rotator 8 is rotated integrally with
the rotatable shaft 5 in the same direction (the direction of the
arrow X). Then, as shown in FIG. 8, when the one side surface 13b
of each protrusion 13 engages the first engaging surface 18b of the
corresponding engaging projection 18, and the first side surface
17a of each opening 17 engages the corresponding roller support 21,
the corresponding rolling element 11 is positioned in the center
portion 19a of the corresponding control surface 19 (this position
is hereinafter called a "neutral position").
[0060] Prior to the engagement of the one side surface 13b of the
protrusion 13 with the first engaging surface 18b, the one side
surface 14d of the corresponding cushion segment 14b engages the
first cushion surface 18a of the corresponding engaging projection
18 to reduce the shocks generated by the engagement.
[0061] At the neutral position, the rolling element 11 is not
clamped between the control surface 19 of the engaging projection
18 and the inner circumferential surface 7d of the outer ring 7a,
so that the driven-side rotator 10 having the engaging projections
18 is allowed to rotate relative to the clutch housing 7 (FIG. 7).
Thus, when the driving-side rotator 8 is further rotated in the
counter-clockwise direction, the rotational force of the
driving-side rotator 8 is transmitted to the driven-side rotator 10
via the protrusions 13, so that the driven-side rotator 10 is
rotated along with the driving-side rotator 8. During this time,
the rotational force is transmitted to each rolling element 11 from
the first side surface 17a of the corresponding opening 17 in the
same direction (the direction of the arrow X), so that the rolling
element 11 moves in the same direction.
[0062] Alternatively, when the rotatable shaft 5 is rotated in the
clockwise direction (the direction of the arrow Y) of FIG. 6, each
rolling element 11 is positioned in the neutral position by the
protrusion 13, as shown in FIG. 9. At this position, the rolling
element 11 is not clamped between the control surface 19 of the
engaging projection 18 and the inner circumferential surface 7d of
the outer ring 7a, so that the driven-side rotator having the
engaging projections 18 is allowed to rotate relative to the clutch
housing 7. Thus, the rotational force of the driving-side rotator 8
is transmitted to the driven-side rotator 10 through the
protrusions 13, so that the driven-side rotator 10 is rotated along
with the driving-side rotator 8.
[0063] Thus, when the driven-side rotator 10 is rotated, the worm
shaft 23, the rotatable coupler 24, the motor protective rubber 25,
the output plate 26 and the output shaft 4 are rotated, so that the
output shaft 4 drives the regulator R to open or close the window
glass W.
[0064] While the motor 1 is not driven, a load applied to the
window glass W acts on the driven-side rotator 10 to rotate the
same. When the driven-side rotator 10 is rotated in the clockwise
direction (the direction of the arrow Y) of FIG. 6, each rolling
element 11 is moved toward the end portion 19b (toward the
intermediate portion 19d) of the control surface 19 of the engaging
projection 18. Then, as shown in FIG. 10, when the rolling element
11 reaches the intermediate portion 19d, the rolling element 11 is
clamed between the control surface 19 and the inner circumferential
surface 7d of the outer ring 7a (locked state). Since the outer
ring 7a is secured, the driven-side rotator 10 cannot be rotated
further, so that the driving-side rotator 8 cannot be rotated by
the driven-side rotator 10.
[0065] When the driven-side rotator 10 is rotated in the
counter-clockwise direction (the direction of the arrow X) of FIG.
6, on the other hand, the driving-side rotator 8 is stopped. Each
rolling element 11 is moved toward the end portion 19c (toward the
intermediate portion 19d) of the control surface 19 of the
corresponding engaging projection 18. Then, when the rolling
element 11 reaches the intermediate portion 19d, as shown in FIG.
11, the rolling element 11 is clamped between the control surface
19 and the inner circumferential surface 7d of the outer ring 7a
(locked state). Since the outer ring 7a is secured, the driven-side
rotator 10 cannot be rotated further, so that the driving-side
rotator 8 cannot be rotated by the driven-side rotator 10.
[0066] As described above, even if a large load is applied to the
window glass W, the window glass W is not opened since the rotation
of the driven-side rotator 10 is prevented.
[0067] Characteristic advantages of the above-described embodiment
will be described below.
[0068] (1) In the control surface 19, the center portion 19a is
positioned radially outward of the straight line K connecting the
opposing end portions 19b, 19c, and/or each intermediate portion
19d positioned between the center portion 19a and the respective
one of the end portions 19b, 19c is arcuately bulged in a radially
outward direction beyond the corresponding straight line J that
connects the center portion 19a and the corresponding one of the
end portions 19b, 19c. Thus, a radial gap between the center
portion 19a of the control surface 19 and the rolling element 11 as
well as a radial gap between the rolling element 11 and the inner
circumferential surface 7d of the outer ring 7 (i.e. difference
between the diameter B of the rolling element 11 and the distance
C) can be minimized, allowing reduction of noises generated
therefrom. Furthermore, when the intermediate portion 19d of the
control surface 19 urges the rolling element 11 against the inner
circumferential surface 7d of the outer ring 7a, a radially
outwardly directed force component of the urging force exerted from
the intermediate portion 19d is increased. Thus, there is less
chance of the rolling element 11 being not clamped between the
control surface 19 and the inner circumferential surface 7d of the
outer ring 7a (i.e., the rolling element being more securely
locked). That is, the transmission of the rotational force of the
driven-side rotator 10 to the driving-side rotator 8 is
prevented.
[0069] (2) The control surface 19 is entirely arcuately bulged. The
arcuately bulged control surface 19 has a radius of curvature
greater than that of the rotational trajectory A of the center
portion 19a of the control surface 19 about the rotational axis of
the driven-side rotator 10. With this arrangement, the
corresponding rolling element 11 can move smoothly along the
control surface 19.
[0070] (3) Each rolling element 11 has the generally cylindrical
shape extending parallel to the central axis of the outer ring 7a,
so that the outer circumferential surface of the rolling element 11
has line contact with both the inner circumferential surface 7d of
the outer ring 7a and the control surface 19 while being clamped
between them. In this way, the rotation of the driven-side rotator
10 can be more securely prevented.
[0071] (4) Each cushion segment 14b of the cushion member 14
reduces the shocks resulting from engagement of the one side
surface 13b of each protrusion 13 to the first engaging surface 18b
of the corresponding engaging projection 18.
[0072] (5) The positional relationship among the rolling elements
11 is maintained by the support member 12. Rattling of each rolling
element 11 can be effectively prevented by the support member 12,
and thereby the vibrations and noises induced by the rattling of
the rolling element 11 can be prevented.
[0073] (6) The clutch 6 is arranged between the rotatable shaft 5
of the motor main body 2 and the worm shaft 23. This arrangement
allows reduction of the required strength of the clutch 6. Thus,
the size of the clutch can be reduced, allowing reduction of the
manufacturing cost.
[0074] The above-described embodiment can be modified as
follows.
[0075] (a) Each control surface 19 of the above-described
embodiment can be changed to any shape as long as it satisfies the
following conditions: the distance between the outer ring 7a and
the control surface 19 decreases from the center portion 19a toward
the opposing end portions 19b, 19c; the center portion 19a is
positioned radially outward of the straight line K connecting the
end portions 19b, 19c; and each intermediate portion 19d is
arcuately bulged in the radially outward direction beyond the
straight line J connecting the center portion 19a and the
corresponding end portion 19b or 19c.
[0076] (b) Each control surface 19 can be changed to a control
surface 31 shown in FIG. 13. In the control surface 31, the center
portion 31a is generally flat. Each intermediate portion 31c
between the center portion 31a and the corresponding end portion
31b of the control surface 31 is arcuately bulged toward the outer
ring 7a beyond the rotational trajectory H of the center portion
31a about the rotational axis of the driven-side rotator, and the
arcuately bulged intermediate portion 31c has a radius of curvature
larger than that of the rotational trajectory H. The diameter B of
the rolling element 11 is substantially equal to a distance F
between the intermediate portion 31c and the inner circumferential
surface 7d of the outer ring 7a. Even if such a change is made, the
advantages (1) and (3)-(6) of the above-described embodiment can be
achieved.
[0077] (c) Each control surface 19 can be changed to a control
surface 32 shown in FIG. 14. The control surface 32 differs from
the control surface 31 only in that the center portion 32a is
arcuately bulged to overlap onto the rotational trajectory H. In
other words, the arcuately bulged center portion 32a is coaxial
with the inner circumferential surface 7d of the outer ring 7a. The
diameter B of the rolling element 11 is substantially equal to the
distance F between the intermediate portion 32c (located between
the center portion 32a and the corresponding end portion 32b) and
the inner circumferential surface 7d of the outer ring 7a. Even if
such a change is made, the advantages (1) and (3)-(6) of the
above-described embodiment can be achieved.
[0078] (d) Each engaging projection 18 of the above-described
embodiment can be changed to an engaging projection 33 shown in
FIG. 15. The engaging projection 33 includes a control surface 34
similar to the control surface 19 along its outer circumferential
surface. The engaging projection 33 has opposing circumferential
end portions that are bulged toward the outer ring 7a to form
bulged portions 35. The bulged portions 35 act as retainer portions
that prevent the rolling element 11 to move out from the space
between the inner circumferential surface 7d of the outer ring 7a
and the control surface 34. The diameter B of the rolling element
11 is substantially equal to the distance F between the
intermediate portion 34c (located between the center portion 34a
and the corresponding end portion 34b) and the inner
circumferential surface 7d of the outer ring 7a. Even if such a
change is made, the advantages similar to those of the
above-described embodiment can be achieved. Furthermore, even if
the rolling element 11 tends to escape from the space between the
inner circumferential surface 7d of the 20 outer ring 7a and the
control surface 34, for example, by slightly flexing each relevant
component, the bulged portions 35 can effectively prevent it.
[0079] (e) In the above-described embodiment, although each rolling
element 11 is generally cylindrically shaped, the rolling element
11 can be generally spherically shaped. Even if such a change is
made, the advantages (1), (2) and (4)-(6) of the above-described
embodiment can be achieved. Furthermore, since the contact between
the generally spherical rolling element and the inner
circumferential surface 7d of the outer ring 7a is minimized,
frictional noises generated therebetween are further reduced.
[0080] (f) The cushion member 14 of the above-described embodiment
can be changed to any other form as long as the shocks, which are
generated when the one side surface 13b (or the other side surface
13c) engages the first engaging surface 18b (or the second engaging
surface 18d), can be reduced. For instance, the cushion segments
14b can be implemented as separate members. Even if such a change
is made, the advantages similar to those of the above-described
embodiment can be achieved. Alternatively, the cushion member 14
can be omitted. Even if such a change is made, the advantages
similar to the advantages (1)-(3), (5) and (6) of the
above-described embodiment can be achieved.
[0081] (g) The support member 12 of the above-described embodiment
can be changed to any form as long as the positional relationship
among the rolling elements 11 can be maintained. Even if such a
change is made, the advantages similar to those of the
above-described embodiment can be achieved. Alternatively, the
support member 12 can be omitted. Even if such a change is made,
the advantages similar to the advantages (1)-(4) and (6) can be
achieved.
[0082] (h) In the above-described embodiment, although the three
rolling elements 11 are provided, the number of the rolling
elements 11 can be any number as long as a plurality of the rolling
elements 11 are present. In such a case, the number of the engaging
slots 15 and the number of the engaging projections 18 need only be
equal to or greater than the number of the rolling elements 11.
[0083] (i) In the above-described embodiment, although the clutch 6
is arranged between the rotatable shaft 5 of the motor main body 2
and the worm shaft 23 in the motor 1, the clutch 6 can be
alternatively arranged between the rotatable coupler 24 and the
output shaft 4. Alternatively, the clutch 6 can be arranged between
the worm wheel 24a and the load. Even if such a change is made, the
advantages similar to the advantages (1)-(5) of the above-described
embodiment can be achieved. Furthermore, the transmission of the
rotational force form the load to the motor main body 2 acting as
the drive source is prevented at the point that is closer to the
load than the rotatable shaft 5 of the motor main body 2.
[0084] Although the clutch 6 of the above-described embodiment is
provided for the motor 1, the clutch 6 can be provided for any
other suitable devices. Furthermore, although the motor 1 is
provided for the power window system, the motor 1 can be provided
for any other suitable devices.
[0085] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore, not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *