U.S. patent application number 09/768049 was filed with the patent office on 2001-08-02 for clutch and motor including such clutch.
Invention is credited to Adachi, Tadashi, Torii, Katsuhiko, Yamamoto, Hiroaki.
Application Number | 20010010280 09/768049 |
Document ID | / |
Family ID | 26584718 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010280 |
Kind Code |
A1 |
Torii, Katsuhiko ; et
al. |
August 2, 2001 |
Clutch and motor including such clutch
Abstract
In a clutch, when a driving-side rotator is rotated, the
driving-side rotator engages a driven-side rotator in a rotational
direction and transmits a rotational force of the driving-side
rotator to the driven-side rotator. When the driven-side rotator is
rotated by an external force, a rolling element is clamped between
the driven-side rotator and an inner circumferential surface of a
housing. At the same time the driven-side rotator is allowed to
rotate while generating a desired frictional force between the
rolling element and the inner circumferential surface of the
housing, so that the rotation of the driven-side rotator is not
transmitted to the driving-side rotator.
Inventors: |
Torii, Katsuhiko;
(Hamamatsu-city, JP) ; Yamamoto, Hiroaki; (Kosai -
city, JP) ; Adachi, Tadashi; (Kosai-city,
JP) |
Correspondence
Address: |
LAW OFFICE OF DAVID G POSZ
2000 L STREET, N.W.
SUITE 200
WASHINGTON
DC
20036
US
|
Family ID: |
26584718 |
Appl. No.: |
09/768049 |
Filed: |
January 24, 2001 |
Current U.S.
Class: |
192/38 ;
74/425 |
Current CPC
Class: |
F16D 43/02 20130101;
Y10T 74/19828 20150115; E05F 15/697 20150115; E05Y 2900/55
20130101; E05F 11/505 20130101; F16D 41/105 20130101 |
Class at
Publication: |
192/38 ;
74/425 |
International
Class: |
F16D 041/06; F16H
001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2000 |
JP |
2000-25196 |
Nov 13, 2000 |
JP |
2000-344894 |
Claims
What is claimed is:
1. A clutch comprising: a housing 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 housing; a driven-side rotator that is connected to a load and
is rotatably received within said housing, 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 clampable means
that is arranged between said driven-side rotator and said inner
circumferential surface of said housing and is positionable between
a clamped position where said clampable means is clamped between
said driven-side rotator and said inner circumferential surface of
said housing and a non-clamped position where said clampable means
is not clamped between said driven-side rotator and said inner
circumferential surface of said housing, said clutch being
characterized in that: when said driving-side rotator is rotated by
a rotational force transmitted from said drive source, rotation of
said driving-side rotator causes said clampable means to be
positioned in said non-clamped position and also to be revolved
therewith, and at the same time said driving-side rotator engages
said driven-side rotator in a rotational direction and transmits a
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 clampable means
is positioned in said clamped position, and at the same time said
driven-side rotator is allowed to rotate while generating a desired
frictional force between said clampable means and said inner
circumferential surface of said housing.
2. A clutch according to claim 1, further characterized in that
said clampable means includes a plurality of clampable elements
provided around a rotational axis of said driving-side rotator,
wherein each of said clampable elements is positioned in said
clamped position when said driven-side rotator is rotated in either
a first or second rotational direction.
3. A clutch according to claim 2, characterized in that said
driven-side rotator includes a plurality of control surfaces
arranged in a one to one relationship with said clampable elements,
wherein each of said clampable elements is to be clamped between a
corresponding one of said control surfaces and said inner
circumferential surface of said housing.
4. A clutch comprising: a housing 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 housing, wherein said driving-side rotator includes a first
engaging portion; a driven-side rotator that is connected to a load
and is rotatably received within said housing, wherein said
driven-side rotator includes a second engaging portion, which
engages said first engaging portion in a rotational direction 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 housing; and a clampable
element that is arranged between said inner circumferential surface
of said housing and said control surface and that has an outer size
smaller than a distance between a circumferential center portion of
said control surface and said inner circumferential surface of said
housing but larger than a distance between each of opposing
circumferential end portions of said control surface and said inner
circumferential surface of said housing, said clutch being
characterized in that: when said driving-side rotator is rotated by
a rotational force transmitted from said drive source, rotation of
said driving-side rotator causes said clampable element to be
substantially positioned at said center portion and also to be
revolved therewith, and at the same time said first engaging
portion engages said second engaging portion in a rotational
direction to transmit a 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 clampable element is clamped between said control
surface and said inner circumferential surface of said housing, and
at the same time said driven-side rotator is allowed to rotate
while generating a desired frictional force between said clampable
element and said inner circumferential surface of said housing.
5. A clutch according to claim 4, characterized in that said
control surface is formed as a single flat surface.
6. A clutch according to claim 4, characterized in that said
clampable element is made of resin material.
7. A clutch according to claim 4, characterized in that an angle
between a first tangent line at a contact point between said
control surface and said clampable means and a second tangent line
at a contact point between said rolling element and said inner
circumferential surface of said housing is in a range of 5 to 20
degrees when said rolling element is clamped between said control
surface and said inner circumferential surface of said housing.
8. A clutch according to claim 6, characterized in that an angle
between a first tangent line at a contact point between said
control surface and said clampable means and a second tangent line
at a contact point between said rolling element and said inner
circumferential surface of said housing is in a range of 10 to 20
degrees when said rolling element is clamped between said control
surface and said inner circumferential surface of said housing.
9. A clutch according to claim 4, characterized in that said
rolling element makes line contact with said inner circumferential
surface of said housing and also with said control surface when
said rolling element is clamped between said control surface and
said inner circumferential surface of said housing.
10. A motor having a clutch according to claim 4.
11. A motor comprising: a clutch including a driving-side rotator
and a driven-side rotator that is engageable with said driving-side
rotator, wherein rotation of said driving-side rotator is
transmitted to said driven-side rotator when said drivingside
rotator is rotated, and wherein said driven-side rotator is allowed
to rotate while exerting a desired rotational load on said
driving-side rotator when said driven-side rotator is rotated; a
motor main body having a rotatable shaft connected to said
driving-side rotator; an output unit including a worm shaft
connected to said driven-side rotator, a worm wheel meshed with
said worm shaft, and an output shaft drivably connected to said
worm wheel, wherein a rotational force of said rotatable shaft is
transmitted to said output shaft through said clutch, said worm
shaft and said worm wheel, and transmission of a rotational force
of said output shaft to said rotatable shaft is prevented at least
by a meshing load between said worm wheel and said worm shaft as
well as by a rotational load of said clutch.
12. A motor comprising: a clutch including a driving-side rotator
and a driven-side rotator that is engageable with said driving-side
rotator, wherein rotation of said driving-side rotator is
transmitted to said driven-side rotator when said driving-side
rotator is rotated, and wherein said driven-side rotator is allowed
to rotate while exerting a desired rotational load on said
driving-side rotator when said driven-side rotator is rotated; a
motor main body having a rotatable shaft connected to said
driving-side rotator; and an output unit including a worm shaft
connected to said driven-side rotator and rotatably supported by
bearings, a worm wheel meshed with said worm shaft, and an output
shaft drivably connected to said worm wheel, wherein a rotational
force of said rotatable shaft is transmitted to said output shaft
through said clutch, said worm shaft and said worm wheel, and
wherein transmission of a rotational force of said output shaft to
said rotatable shaft is prevented at least by a meshing load
between said worm wheel and said worm shaft, by a frictional load
between said worm shaft and said bearings and by a rotational load
of said clutch.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Applications No. 2000-25196 filed on Feb.
2, 2000 and No. 2000-344894 filed on Nov. 13, 2000.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a clutch that allows
rotation of a driven-side rotator while making the driven-side
rotator difficult to rotate and also to a motor having such a
clutch.
[0003] A motor of a power window system has a motor main body and
an output unit. The output unit transmits rotation of a rotatable
shaft of the motor main body to a regulator (located on a driven
side) via a worm shaft to reduce a rotational speed of the
rotatable shaft before it is transmitted to the regulator. The worm
shaft is formed integrally with the rotatable shaft or is arranged
coaxial with the rotatable shaft. When the motor is driven, the
rotation of the rotatable shaft is transmitted to the output unit
via the worm shaft. After the output unit reduces the rotational
speed of the rotatable shaft, the regulator converts the rotational
movement to reciprocal movement. As a result, a window glass is
moved up and down by the regulator to close and open the window
glass, respectively.
[0004] In this type of power window system, when the motor is not
driven, a downward load applied to the window glass is converted to
a rotational force by the regulator and is transmitted to the
rotatable shaft of the motor main body to rotate the same. This
transmission of the rotation causes forceful downward movement of
the window glass to open the same when an external force is applied
to the window glass, causing likelihood of burglarization.
[0005] In order to prevent such transmission of the rotation, a
motor having a clutch that prevents the transmission of the
rotation from a driven-side rotator to a driving-side rotator has
been proposed. In this motor, the clutch transmits the rotation of
the driving-side rotator to the driven-side rotator but does not
transmit the rotation of the driven-side rotator to the
driving-side rotator.
[0006] It would be easier and better if the clutch is designed such
that the transmission of the rotation from the driven-side rotator
to the driving-side rotator is prevented by the entire motor or by
the entire power window system in consideration of loss of the
rotational force at each sliding portion within it. However, the
above prior art prevents the transmission of the rotational force
from the driven-side rotator to the driving-side rotator only by
the clutch itself. Thus, in order to completely prevent the
transmission of the rotational force from the driven-side rotator
to the driving-side rotator only by the clutch, each component of
the clutch must be manufactured with a high degree of accuracy,
resulting in the higher costs. As a result, there is a need for an
inexpensive clutch that makes the rotation of the driven-side
rotator difficult instead of completely preventing the transmission
of the rotational force from the driven-side rotator to the
driving-side rotator.
[0007] This fact is not only in the clutch used in the power window
system but is also equally in any other devices that require a
clutch and also require the rotation of the driven-side rotator to
be allowed while making the rotation of the driven-side rotator
difficult.
SUMMARY OF THE INVENTION
[0008] It is therefore an objective of the present invention to
provide a clutch that transmits rotation of a driving-side rotator
driven by a drive source to a driven-side rotator and that allows
the rotation of the driven-side rotator while making the
driven-side rotator difficult to rotate when the driven-side
rotator is rotated by a load applied to it.
[0009] It is another objective of the present invention to provide
a motor having such a clutch.
[0010] To achieve the above objectives, there is provided a clutch
including a housing, a driving-side rotator, a driven-side rotator
and a clampable element. The housing 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
housing. The driven-side rotator is connected to a load and is
rotatably received within the housing. Furthermore, the driven-side
rotator is connected to the driving-side rotator in a manner
allowing relative rotation of the driven-side rotator within a
predetermined range in a rotational direction. The clampable
element is arranged between the driven-side rotator and the inner
circumferential surface of the housing and is positionable between
a clamped position where the clampable element is clamped between
the driven-side rotator and the inner circumferential surface of
the housing and a non-clamped position where the clampable element
is not clamped between the driven-side rotator and the inner
circumferential surface of the housing.
[0011] When the driving-side rotator is rotated, rotation of the
driving-side rotator causes the clampable element to be positioned
in the non-clamped position and also to be revolved therewith. At
the same time, the driving-side rotator engages the driven-side
rotator in a rotational direction and transmits a rotational force
of the driving-side rotator to the driven-side rotator. When the
driven-side rotator is rotated, the clampable element is positioned
in the clamped position, and at the same time the driven-side
rotator is allowed to rotate while generating a desired frictional
force between the clampable element and the inner circumferential
surface of the housing.
[0012] Furthermore, there is also provided a motor having the above
clutch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] 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:
[0014] FIG. 1 is an exploded perspective view of a motor according
to an embodiment of the present invention;
[0015] FIG. 2 is a schematic plan cross-sectional view of the motor
shown in FIG. 1;
[0016] FIG. 3 is an exploded perspective view of a clutch according
the embodiment;
[0017] FIG. 4 is a schematic partial longitudinal cross-sectional
view of the clutch according to the embodiment;
[0018] FIG. 5 is a schematic cross-sectional view of the clutch
according to the embodiment;
[0019] FIG. 6 is a partial schematic cross-sectional view of the
clutch according to the embodiment;
[0020] FIG. 7 is a partial schematic cross-sectional view of the
clutch according to the embodiment;
[0021] FIG. 8 is a schematic cross-sectional view of the clutch
according to the embodiment;
[0022] FIG. 9 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0023] FIG. 10 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0024] FIG. 11 is another schematic cross-sectional view of the
clutch according to the present embodiment;
[0025] FIG. 12 is a schematic side view of a power window system
according to the embodiment;
[0026] FIG. 13 is a partial cross-sectional view illustrating a
modification of the clutch; and
[0027] FIG. 14 is another partial cross-sectional view illustrating
another modification of the clutch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] One embodiment of the present invention will be described
with reference to a power window system shown in FIGS. 1-12.
[0029] 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 or down, respectively.
[0030] As shown in FIG. 1, 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. At the distal end of the motor
main body 2 (rotatable shaft 5), a clutch 6 is provided.
[0031] 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, three rolling elements 11 acting as clampable elements
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 housed within the clutch housing 7 to constitute one
functional unit (clutch 6).
[0032] 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-shaped 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 with 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.
[0033] 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.
[0034] A cushion member 14 made of rubber material is securely
coupled to the coupling groove 13a of each protrusion 13. More
particularly, as shown in FIG. 3, 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 and extend in an axial direction. 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.
[0035] As shown in FIG. 5, 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 (circumferential side surface) 13b of one
protrusion 13 and an opposing side surface 13c of the next
protrusion 13 and also between one side surface 14d
(circumferential side surface) 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 that extend in an axial direction are formed at the
outer circumference of the disk body 8b where the protrusion 13 is
not present. 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.
[0036] 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.
[0037] 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). 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.
[0038] As shown in FIGS. 3 and 5, 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. The engaging protrusion 18 is
received in the corresponding engaging slot 15.
[0039] As shown in FIG. 5, 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 counter-clockwise direction (the direction of the arrow X), as
shown in FIG. 8.
[0040] 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 a 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.
[0041] A control surface 19 is formed on an outer circumferential
surface of each engaging projection 18. As shown in FIG. 6, in the
control surface 19, opposing circumferential end portions 19b, 19c
are located radially outward of a center portion 19a. The control
surface 19 forms a substantially straight line between the center
portion 19a and each of the end portions 19b, 19c. That is, a
distance between the control surface 19 and the inner
circumferential surface 7d of the outer ring 7a decreases from the
center portion 19a (a distance L1) toward the respective end
portions 19b, 19c (a distance L2).
[0042] Each rolling element 11 is a generally cylindrical body made
of metal 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. As shown in FIG. 6, a diameter L0 of the rolling element
11 is smaller than the distance L1 between the center portion 19a
of the control surface 19 and the inner circumferential surface 7d
of the outer ring 7a. It is however larger than the distance L2
between each of the end portions 19b, 19c of the control surface 19
and the inner circumferential surface 7d of the outer ring 7a.
[0043] For instance, when the driven-side rotator 10 is rotated in
the clockwise direction (the direction of the arrow Y) of FIG. 5 by
the clutch 6 alone, the rolling element 11 is clamped between the
control surface 19 and the inner circumferential surface 7d of the
outer ring 7a, as shown in FIG. 10. This is more clearly shown by
enlargement in FIG. 7. In this embodiment, the control surface 19
is formed such that when the rotational force is further applied to
the driven-side rotator 10 in the same direction, the rolling
element 11 is revolved along with the driven-side rotator 10 while
the rolling element 11 making sliding engagement with the inner
circumferential surface 7d of the outer ring 7a and generating a
desired frictional force therebetween.
[0044] More specifically, in the present embodiment, an angle
.theta. between a tangent line A at a contact point P between the
control surface 19 and the rolling element 11 and a tangent line B
at a contact point Q between the rolling element 11 and the inner
circumferential surface 7d of the outer ring 7a is "15 degrees".
Various angles .theta. were studied and tested to find the most
appropriate angle. As a result, when .theta.=15 degrees, the most
desirable frictional force (in this instance, a coefficient .theta.
of friction of the control surface 19 is "0.05 to 0.3") can be
provided. According to this study, when the angle .theta. is
between 5 to 20 degrees, a desirable frictional force can be
generated. Furthermore, when the angle .theta. is between 10 to 20
degrees, a further desirable frictional force can be generated.
[0045] Because of the frictional force, the driving-side rotator 8
cannot be easily rotated by the driven-side rotator 10.
Furthermore, the motor 1 having the above type of clutch 6 is
arranged such that the rotation of the output shaft 4 of the motor
1 is prevented since the driving force to rotate the output shaft 4
is lost before it is transmitted to the output shaft 4, for
example, at the clutch 6, the respective sliding parts (e.g.,
meshed gear portions or bearing portions) or the like.
[0046] The support member 12 is made of resin material and includes
a ring plate 20 and three roller supports 21. The ring plate 20 is
slidably received between the cover 7c of the clutch housing 7 and
the protrusions 13 of the driving-side rotator 8. Each roller
support 21 extends in the axial direction from the ring plate 20 to
rotatably support the corresponding rolling element 11 in parallel
with a rotational axis thereof. The roller supports 21 are arranged
at equal angular intervals on the ring plate 20.
[0047] 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 movable in
the radial direction of the ring plate 20.
[0048] In this embodiment, the components 11, 13, 18 and 21 are
geometrically arranged such that, 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.
[0049] Furthermore, as shown in FIG. 9, the components 11, 13, 18
and 21 are further geometrically arranged such that 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.
[0050] 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.
[0051] A worm shaft 23 is rotatably supported by bearings 28a, 28b
held by 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.
[0052] 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. 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. A plate
cover 27 is secured to an opening of the wheel housing 22c.
[0053] The power window system (clutch 6) having the above
construction operates as follows.
[0054] 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. 5, 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 defined as a neutral position.
[0055] 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.
[0056] 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. 6).
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.
[0057] When the rotatable shaft 5 is rotated in the clockwise
direction (the direction of the arrow y) of FIG. 5, 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 10 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.
[0058] 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.
[0059] 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. 5, each rolling
element 11 is moved toward the end portion 19b of the control
surface 19 of the engaging projection 18. Then, as shown in FIG.
10, the rolling element 11 is clamped between the control surface
19 and the inner circumferential surface 7d of the outer ring
7a.
[0060] If the driven-side rotator 10 further rotates in the same
direction, the rolling element 11 slidingly engages the inner
circumferential surface 7d of the outer ring 7a and thereby
generates the desired frictional force due to the above shape of
the control surface 19. Thus, the rotation of the driven-side
rotator 10 becomes difficult. As a result, in the motor 1 having
the above type of clutch 6, the output shaft 4 is prevented from
rotation due to the loss of the driving force, for example, at the
clutch 6, the respective sliding parts (e.g., meshed gear portions
or bearing portions) of the motor 1 or the like.
[0061] When the driven-side rotator 10 is rotated in the
counter-clockwise direction (the direction of the arrow X) of FIG.
5, while the driving-side rotator 8 is stopped, each rolling
element 11 is moved toward the end portion 19c of the control
surface 19 of the engaging projection 18. Then, 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.
[0062] If the driven-side rotator 10 further rotates in the same
direction, similar to the above case, the rotation of the
driven-side rotator 10 becomes difficult due to the desired
frictional force generated upon engagement of the rolling element
11 with the inner circumferential surface 7d of the outer ring 7a.
As a result, the rotation of the output shaft 4 of the motor 1 is
prevented.
[0063] As described above, even if a large load is applied to the
window glass W, the window glass W is not opened by such a load
since the rotation of the output shaft 4 of the motor 1 is
prevented.
[0064] Characteristic advantages of the above embodiment will be
described below.
[0065] (1) The clutch 6 is constructed such that when the
driven-side rotator 10 is rotated by the load, each rolling element
11 is positioned to be clamped between the driven-side rotator 10
and the inner circumferential surface 7d of the outer ring 7a. At
the same time, the rotation of the driven-side rotator 10 is
allowed while generating the frictional force between the rolling
element 11 and the inner circumferential surface 7d of the outer
ring 7a. As a result, instead of completely preventing the
transmission of the rotational force of the driven-side rotator 10
to the driving-side rotator 8 by the clutch 6 alone, the
driven-side rotator 10 is made difficult to rotate. Thus, there is
no need to manufacture each component of the clutch 6 at a high
degree of accuracy. As a result, the costs of the clutch 6 can be
reduced
[0066] (2) The clutch 6 can be easily designed since it is only
required to make the shape of the control surface 19 of the
driven-side rotator 10 to operate in the above manner.
[0067] (3) Each cushion segment 14b of the cushion member 14
reduces the shocks resulting from engagement of the one side
surface 13b to the first engaging surface 18b.
[0068] (4) 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.
[0069] (5) The clutch 6 is arranged between the rotatable shaft 5
of the motor main body 2 and the worm shaft 23. That is, the clutch
6 is arranged at the position where a relatively small torque is
applied. Thus, a strength required for the clutch 6 can be reduced.
As a result, a size of the clutch 6 can be reduced, allowing
reduction of the costs.
[0070] The above embodiment can be modified as follows.
[0071] (a) The control surface 19 can have any other appropriate
shape. For instance, the control surface 19 can be arcuately bulged
in a radially outward direction.
[0072] Similar to the control surface 19 of the above embodiment,
the control surface only needs to have a shape that allows the
rolling element 11 to be positioned in place where the rolling
element 11 is clamped between the driven-side rotator 10 and the
inner circumferential surface 7d of the outer ring 7a in a manner
that allows rotation of the driven-side rotator 10 while generating
a desired frictional force between the rolling element 11 and the
inner circumferential surface 7d of the outer ring 7a when the
driven-side rotator 10 is rotated by the load. For instance, if the
control surface is arcuate, a radius of curvature of the control
surface should be such that although it is not depicted, similar to
FIG. 7, an angle .theta. between the tangent line A at the contact
point P between the control surface and the rolling element 11 and
the tangent line B at the contact point Q between the rolling
element 11 and the inner circumferential surface 7d of the outer
ring 7a falls within a desired range (5 to 20 degrees).
[0073] Furthermore, as shown in FIG. 13, the control surface 19 can
be made as a single flat surface. Although it is not depicted,
similar to FIG. 7, the control surface should be designed such that
an angle .theta. between the tangent line A at the contact point P
between the control surface 19 and the rolling element 11 and the
tangent line B at the contact point Q between the rolling element
11 and the inner circumferential surface 7d of the outer ring 7a
falls within a desired range (5 to 20 degrees). In this way, the
control surface 19 can be made as the single flat surface, so that
the control surface 19 can be manufactured more easily.
[0074] (b) The material of each rolling element 11 is not limited
to the metal. For instance, as shown in FIG. 14, rolling elements
31 made of resin material can be used in place of the rolling
elements 11. In this way, each rolling element 31 made of the resin
material can reduce impact noise that is generated when the rolling
element 31 hits other member, so that noises generated from the
clutch 6 and therefore from the motor 1 can be reduced.
[0075] (c) The shape of each rolling element 11 is not limited to
this. For instance, a spherical element can be used. Also, a
clampable element having non-circular cross-section, i.e., the
non-rotatable clampable element can be used in place of the rolling
element 11.
[0076] (d) The shape and position of the cushion member 14 are not
limited to those shown in FIGS. 3 and 5 as long as the collision
shocks between the driving-side rotator 8 and the driven-side
rotator 10 can be reduced. Alternatively, the cushion member 14 can
be omitted.
[0077] (e) The shape of the support member 12 is not limited to
this. Alternatively, the support member 12 can be omitted.
[0078] (f) 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. Furthermore, the shape of
the support member 12 should be modified to coincide with the
number of the rolling elements 11.
[0079] (g) The clutch 6 can be placed at any other suitable
position. For instance, the clutch 6 can be arranged between the
rotatable coupler 24 and the output shaft 4.
[0080] (h) The clutch 6 can be provided in a motor of any apparatus
or system other than the power window system. Alternatively, the
clutch 6 can be provided in any device other than the motor.
[0081] 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.
* * * * *