U.S. patent application number 09/832099 was filed with the patent office on 2001-10-18 for one-way clutch.
Invention is credited to Domoto, Masakazu, Nagaya, Shuichi, Tokuda, Makoto.
Application Number | 20010030095 09/832099 |
Document ID | / |
Family ID | 18622874 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010030095 |
Kind Code |
A1 |
Nagaya, Shuichi ; et
al. |
October 18, 2001 |
One-way clutch
Abstract
A one-way clutch is arranged so that a plurality of intermediate
members, which are each retained in a cage, each wedge between
inner and outer rings when the inner and outer rings relatively
rotate in a locking direction and each rock opposite to the
direction of the wedging when the inner and outer rings relatively
rotate in an idling direction, are pressed in the direction of the
wedging by spring members. In this one-way clutch, each spring
member includes a pair of coil springs that are juxtaposed to align
in an axial direction of the inner and outer rings, are retained at
one ends thereof by the cage and resiliently contact at the other
ends thereof with the intermediate member. The one ends of both the
coil springs are connected together through a connecting portion.
The coil springs and the connecting portion are formed of a single
wire.
Inventors: |
Nagaya, Shuichi; (Kobe-shi,
JP) ; Domoto, Masakazu; (Iwata-shi, JP) ;
Tokuda, Makoto; (Iwata-shi, JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
8180 GREENSBORO DRIVE
SUITE 800
MCLEAN
VA
22102
US
|
Family ID: |
18622874 |
Appl. No.: |
09/832099 |
Filed: |
April 11, 2001 |
Current U.S.
Class: |
192/45.1 ;
192/41A |
Current CPC
Class: |
F16D 2041/0605 20130101;
F16D 41/067 20130101; F16D 41/07 20130101 |
Class at
Publication: |
192/45.1 ;
192/41.00A |
International
Class: |
F16D 041/07 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2000 |
JP |
2000-110350 |
Claims
What is claimed is:
1. A one-way clutch comprising: an inner ring; an outer ring
disposed coaxially around an outer periphery of the inner ring and
assembled relatively rotatably with the inner ring; a cage disposed
between the inner and outer rings for relative rotation with
respect to the inner and outer rings; a plurality of intermediate
members that are each retained in the cage so as to be changeable
in position in a plane orthogonal to the axis of the inner and
outer rings, change the position thereof to wedge between the inner
and outer rings upon relative rotation of the inner and outer rings
in a locking direction to effect torque transmission between the
inner and outer rings, and change the position thereof opposite to
the direction of wedging between the inner and outer rings upon
relative rotation of the inner and outer rings in an idling
direction to block torque transmission between the inner and outer
rings; and a plurality of spring members, disposed correspondingly
to the intermediate members in the cage, for pressing the
corresponding intermediate members to wedge the intermediate
members between the inner and outer rings, wherein each of the
spring members includes: a plurality of coil springs that are
juxtaposed to align in an axial direction of the inner and outer
rings and extend in a direction to press the corresponding
intermediate member, are retained at one ends thereof by the cage
and resiliently contact at the other ends thereof with the
intermediate member; and a connecting portion for connecting the
one ends of the plurality of coil springs together.
2. The one-way clutch of claim 1, wherein the number of coil
springs provided in each of the spring members is two, and the two
coil springs and the connecting portion of each of the spring
members are formed of a single wire.
3. The one-way clutch of claim 1 or 2, wherein the end of a wire
forming the other end of the coil spring is formed to avoid contact
with the inner and outer rings.
4. The one-way clutch of claim 1, 2 or 3, wherein the one-way
clutch is disposed in a torque transmission path for transmitting
torque of a crank shaft revolving with angular velocity variations
due to an explosion stroke of a vehicle engine to an input shaft of
auxiliary equipment through a power transmission belt.
5. The one-way clutch of claim 4, wherein the inner ring is
provided to be connectable with one of the crank shaft of the
vehicle engine and the input shaft of the auxiliary equipment, and
the outer ring is provided with a pulley section for training the
power transmission belt therearound to rotate unitarily with the
outer ring.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a one-way clutch that effects and
blocks torque transmission between inner and outer rings by
shifting intermediate members according to the direction of
relative rotation between the inner and outer rings, and
particularly relates to improvement of a spring member for pressing
and urging each of the intermediate members into the shift in a
direction to wedge between the inner and outer rings.
DESCRIPTION OF THE PRIOR ART
[0002] As for example disclosed in Japanese Unexamined Patent
Publication No. 61-228153, it is known that in a belt type
auxiliary equipment driving apparatus for a vehicle engine, a
one-way clutch is disposed, in order to transmit torque of a crank
shaft revolving with angular velocity variations due to an
explosion stroke of the engine to input shafts of auxiliary
equipment through a belt, in a torque transmission path so that for
a period of increase in angular velocity during the angular
velocity variations torque transmission is effected between the
crank shaft and the input shafts of the auxiliary equipment to
drive the input shafts into rotation, while for a period of
decrease in angular velocity during the angular velocity variations
the torque transmission is blocked to avoid torque due to moment of
inertia of the input shafts from being transmitted to the crank
shaft whereby load placed on the belt is reduced to provide
elongated belt life.
[0003] Now, the operation of the above one-way clutch will be
described. As shown in FIG. 10, each of intermediate members c is
retained by a cage d between inner and outer rings a and b for
clockwise and counterclockwise rocking motion in the figure and is
normally pressed clockwise in the figure by a flat spring e as a
spring member to wedge between the inner and outer rings a and b.
For the period of increase in angular velocity, for example, when
the outer ring b relatively rotates in its locking direction
(clockwise in the figure) with respect to the inner ring a, the
relative rotation causes each intermediate member c to wedge
between the inner and outer rings a and b thereby effecting torque
transmission between the inner and outer rings a and b. On the
other hand, for the period of decrease in angular velocity, when
the outer ring b relatively rotates in its idling direction, the
relative rotation causes each intermediate member c to rock
opposite to the direction to wedge between the rings against the
pressing force of the flat spring e. This produces slippage between
each intermediate member c and the inner and outer rings a, b
thereby blocking torque transmission.
[0004] As the spring member, a coil spring is generally used apart
from the above-mentioned flat spring e. A comparison of both the
springs indicates that the coil spring is more suitable in
durability. Here, description will also be made about the structure
of the one-way clutch when the coil spring is used as the spring
member. As shown in FIGS. 11 and 12, out of a pair of
circumferentially opposed wall surfaces of each retaining hole g of
the cage d, the wall surface on the opposite side to the wall
surface of a protruding wall for supporting the intermediate member
c to allow its rocking motion (left-hand side in FIG. 12) is formed
with a recess h and the root end of the coil spring f (left end in
FIGS. 11 and 12) is accommodated in the recess h. It is to be noted
that the root end of the coil spring f is generally closely wound,
though its illustration is omitted.
[0005] Meanwhile, in the one-way clutch, torque transmission is
started not at a point in time when the angular velocities of the
inner and outer rings a and b are coincident with each other for
the period of increase in angular velocity but slightly behind the
point in time. If this is described using the above case as an
example, torque of the outer ring b is started to be transmitted to
the inner ring a at a point in time when the outer ring b is
further increased in angular velocity to relatively rotate by a
certain angle with respect to the inner ring a after the angular
velocity of the outer ring b has been increased for the period of
increase in angular velocity until it matches the angular velocity
of the inner ring a. The relative angle between the inner and outer
rings a and b at the point in time is called "a delay angle". If
the delay angle is too large, excellent response to an angular
velocity variation cannot be attained and therefore proper torque
transmission cannot be provided.
[0006] The reasons for the occurrence of the delay angle are not
only that each intermediate member c essentially requires a certain
time to rock to wedge between the inner and outer rings a and b due
to relative rotation of the inner and outer rings a and b in the
locking direction but also that each intermediate member c vibrates
due to angular velocity variations. Namely, when each intermediate
member c vibrates, slippage occurs between the intermediate member
c and each of the inner and outer rings a and b even if the inner
and outer rings a and b relatively rotate in the locking direction,
and therefore its wedging movement between the inner and outer
rings a and b is further delayed so that the intermediate member c
cannot follow an angular velocity variation.
[0007] Further, the frequency of angular velocity variations of the
vehicle engine is low at low engine speeds and high at high engine
speeds. For example, in a four-cycle four-cylinder engine involving
two explosion strokes for one revolution of the crank shaft, the
frequency of angular velocity variations reaches 100 to 200 Hz at
high engine speeds where the speed of the crank shaft reaches 3000
to 6000 rpm.
[0008] Accordingly, in order to attain excellent response to
angular velocity variations in the entire speed range of the
vehicle engine, it is necessary to allow each intermediate member c
to sufficiently follow high-frequency angular velocity variations
at high engine speeds. To satisfy this requirement, the spring
member must have a large spring constant enough to suppress
variations of the intermediate member c due to such high-frequency
angular velocity variations.
Problems to be Solved
[0009] However, the conventional one-way clutch using the coil
springs f as the spring members generally has the disadvantage of a
lower spring constant of the coil spring f as compared with the
flat spring e of equal size in its operating direction. As can be
seen from this point, the coil spring f is excellent in durability
over the flat spring e, whereas the one-way clutch using the coil
spring f has a problem of the difficulty in attaining excellent
response to high-frequency variations as described above as
compared with the one-way clutch using the flat spring e. In this
case, if the spring constant is increased by increasing the size of
each coil spring f in the operating direction, the one-way clutch
will be greater. This causes a new problem of the difficulty in
disposing the one-way clutch in an engine room of the vehicle.
[0010] Further, the conventional one-way clutch using the coil
springs f has another problem. Specifically, as shown with
exaggeration in FIG. 13, the root end of the coil spring f has a
tendency to easily extrude from the recess h toward the outer ring
b as a result of relative rotation between the inner and outer
rings a and b. Further, if expansion and contraction of the coil
spring f itself resulting from rocking motion of the intermediate
member c is added to this tendency, the distal end (right end in
FIG. 14) of the coil spring f is also displaced toward the outer
ring b as shown with exaggeration in the figure. Furthermore, since
the rotation of the coil spring f itself around the axis of the
coil also concurs, these events results in easily providing an
unstable pressing force on the intermediate member c. This also
invites insufficient suppression of the above-mentioned vibrations
of the intermediate member c.
[0011] The present invention has been made in view of the foregoing
points and therefore a major object of the present invention is to
obtain, in using coil springs as spring members for a one-way
clutch into which torque accompanied with high-frequency angular
velocity variations is input, a high spring constant equivalent to
the case of using flat springs even if the size of the coil spring
in its operating direction is not increased, thereby providing a
one-way clutch having excellent response to input torque
accompanied with high-frequency angular velocity variations and
excellent durability.
SUMMARY OF THE INVENTION
[0012] The present invention takes the following measures to solve
the above problems.
[0013] A first inventive measure is directed to a one-way clutch
comprising: an inner ring; an outer ring disposed coaxially around
an outer periphery of the inner ring and assembled relatively
rotatably with the inner ring; a cage disposed between the inner
and outer rings for relative rotation with respect to the inner and
outer rings; a plurality of intermediate members that are each
retained in the cage so as to be changeable in position in a plane
orthogonal to the axis of the inner and outer rings, change the
position thereof to wedge between the inner and outer rings upon
relative rotation of the inner and outer rings in a locking
direction to effect torque transmission between the inner and outer
rings, and change the position thereof opposite to the direction of
wedging between the inner and outer rings upon relative rotation of
the inner and outer rings in an idling direction to block torque
transmission between the inner and outer rings; and a plurality of
spring members, disposed correspondingly to the intermediate
members in the cage, for pressing the corresponding intermediate
members to wedge the intermediate members between the inner and
outer rings.
[0014] Each of the spring members includes: a plurality of coil
springs that are juxtaposed to align in an axial direction of the
inner and outer rings and extend in a direction to press the
corresponding intermediate member, are retained at one ends thereof
by the cage and resiliently contact at the other ends thereof with
the intermediate member; and a connecting portion for connecting
the one ends of the plurality of coil springs together.
[0015] In this inventive measure, since each of the spring members
of the one-way clutch includes the plurality of coil springs
juxtaposed with respect to the corresponding intermediate member,
the entire spring constant of the spring member is obtained by
summing up spring constants of the coil springs. Accordingly, even
if the natural length of each coil spring is not increased, the
spring constant of the spring member on the intermediate member
becomes large as a whole.
[0016] Further, since the one ends of the coil springs are
connected together through the connecting portion, each coil spring
is restrained against rotation around the coil axis and when each
coil spring is retained at its one end by the cage, the other end
of the coil spring is easily fixed using the connecting portion.
Accordingly, each coil spring makes its pressing conditions against
the intermediate member steady and therefore the pressing force on
the intermediate member is also stabilized. Furthermore, since the
plurality of coil springs are formed integrally through the
connecting portion, increase in number of components can be avoided
in spite of use of the plurality of coil springs for each
intermediate member.
[0017] In a second inventive measure, when the number of coil
springs provided in each of the spring members is two in the first
inventive measure, the two coil springs and the connecting portion
of each of the spring members are formed of a single wire.
[0018] With this inventive measure, since the two coil springs and
the connecting portion are formed of a single wire, the connection
of both the coil springs through the connecting portion can be made
optimally.
[0019] In a third inventive measure, the end of a wire forming the
other end of the coil spring in the first and second inventive
measures is formed to avoid contact with the inner and outer
rings.
[0020] With this inventive measure, when torque is input to the
one-way clutch to rotate the cage, in some cases attendant
centrifugal forces or a position change of the intermediate member
may change the position of the other end of the coil spring in a
radial direction of the inner and outer rings. In this case, since
the wire end forming the other end of the coil spring does not
contact with the inner and outer rings, there can be obviated the
occurrence of events due to engagement of the wire end with the
inner and outer rings, i.e., an event that the operation of the
coil spring is blocked or an event that the contact surfaces of the
inner and outer rings with the intermediate member are damaged to
adversely affect the position change of the intermediate
member.
[0021] In a fourth inventive measure, the one-way clutch in the
first to third inventive measures is disposed in a torque
transmission path for transmitting torque of a crank shaft
revolving with angular velocity variations due to an explosion
stroke of a vehicle engine to an input shaft of auxiliary equipment
through a power transmission belt.
[0022] With this inventive measure, torque accompanied with angular
velocity variations due to the explosion stroke of the vehicle
engine is input to the one-way clutch in the torque transmission
path in which torque of the crank shaft of the vehicle engine is
transmitted to the input shaft of the auxiliary equipment through
the power transmission belt. Therefore, each intermediate member
vibrates due to the angular velocity variations. Particularly for a
four-cylinder four-cycle engine, the frequency of angular velocity
variations is a high frequency in the range of 100 to 200 HZ at
high engine speeds of 3000 to 6000 rpm. Accordingly, excellent
properties of the spring member in the first to third inventive
measures can be exhibited specifically and properly.
[0023] In a fifth inventive measure, based on the fourth inventive
measure, the inner ring is provided to be connectable with one of
the crank shaft of the vehicle engine and the input shaft of the
auxiliary equipment, and the outer ring is provided with a pulley
section for training the power transmission belt therearound to
rotate unitarily with the outer ring.
[0024] With this inventive measure, when the one-way clutch is
disposed in a belt type auxiliary equipment driving apparatus for
an vehicle engine, the inner ring is connected to the crank shaft
of the vehicle engine or the input shaft of the auxiliary equipment
and the power transmission belt is trained around the outer ring.
In this case, since the outer ring is provided unitarily rotatably
with the pulley section for training the power transmission belt
thereover, disposition of the one-way clutch in the belt type
auxiliary equipment driving apparatus is facilitated.
Effects of Invention
[0025] According to the present invention, in a one-way clutch
which has a plurality of intermediate members for changing their
positions in a direction to wedge between inner and outer rings
when the inner and outer rings relatively rotate in a locking
direction and changing their positions opposite to the direction to
wedge between the inner and outer rings when the inner and outer
rings relatively rotate in an idling direction and in which the
intermediate members are pressed by corresponding spring members to
change their positions in the direction to wedge between the inner
and outer rings, each of the spring members includes: a plurality
of coil springs that are juxtaposed with respect to the
intermediate member, are retained at one ends thereof by a cage and
resiliently connect at the other ends thereof with the intermediate
member; and a connecting portion for connecting the plurality of
coil springs together. Therefore, the entire spring constant of the
spring member can be increased even if the size of each coil spring
in its operating direction is not increased, each coil spring can
be restrained against rotation around the coil axis, and each coil
spring can be fixed at its one end with the use of the connecting
portion. Accordingly, even on receipt of a centrifugal force or
vibration due to high-speed rotation, each coil spring can make its
pressing conditions against the intermediate member steady thereby
providing a stable pressing force of each coil spring. Further,
integral configuration of the plurality of coil springs can avoid
increase in number of components due to use of the plurality of
coil springs for each intermediate member.
[0026] According to the second inventive measure, when the number
of coil springs for each spring member is two, the two coil springs
and the connecting portion are formed of a single wire. Therefore,
the two coil springs can be optimally connected together in one
piece.
[0027] According to the third inventive measure, since the wire end
at the other end of each coil spring resiliently contacting with
the intermediate member is provided to avoid contact with the inner
and outer rings, there can be obviated the occurrence of events due
to engagement of the wire end with the inner and outer rings, i.e.,
an event that the operation of the coil spring itself is blocked or
an event that the contact surfaces of the inner and outer rings
with the intermediate member are damaged.
[0028] According to the fourth inventive measure, since the one-way
clutch is used for a belt type auxiliary equipment driving
apparatus for a vehicle engine frequently producing high-frequency
vibrations, this properly provides the effects of the inventive
measure of claim 1.
[0029] According to the fifth inventive measure, since the pulley
section for training the power transmission belt therearound is
provided around the outer ring so that the one-way clutch can be
used as a one-way clutch-integrated pulley, the one-way clutch
according to the present invention can be readily disposed in the
belt type auxiliary equipment driving apparatus for a vehicle
engine.
BRIEF DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is an exploded perspective view showing an essential
part of a one-way clutch-integrated pulley according to a first
embodiment of the present invention.
[0031] FIG. 2 is a view showing the essential part of the one-way
clutch-integrated pulley when viewed from an outer ring.
[0032] FIG. 3 is a cross-sectional view taken along the line
III-III of FIG. 2.
[0033] FIG. 4 is a cross-sectional view taken along the line IV-IV
of FIG. 3.
[0034] FIG. 5 is a schematic view showing the layout of an
auxiliary equipment driving apparatus for a vehicle engine.
[0035] FIG. 6 is a longitudinal cross-sectional view showing the
entire structure of the one-way clutch-integrated pulley.
[0036] FIG. 7 is a schematic view showing how an experimental
example is to be performed.
[0037] FIG. 8 is a plot showing the change in rotational speed of
an inner ring due to the delay angle under conditions of
high-frequency speed variations of a vehicle engine in an inventive
example together with the change in rotational speed of the outer
ring.
[0038] FIG. 9 is a plot showing the delay angles of inventive and
comparative examples together.
[0039] FIG. 10 is a transverse cross-sectional view showing an
essential part of a one-way clutch using a flat spring.
[0040] FIG. 11 is a corresponding view of FIG. 11 which shows a
conventional one-way clutch using a coil spring.
[0041] FIG. 12 is a corresponding view of FIG. 4, which shows an
essential part of the conventional one-way clutch.
[0042] FIG. 13 is a corresponding view of FIG. 12, which shows with
exaggeration the conventional one-way clutch with the root end of
the coil spring changed in position toward the outer ring.
[0043] FIG. 14 is a corresponding view of FIG. 12, which shows with
exaggeration the conventional one-way clutch with the distal end of
the coil spring changed in position toward the outer ring.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0044] Hereinafter, an embodiment of the present invention will be
described in detail with reference to the drawings.
[0045] FIG. 5 schematically shows the layout of a belt type
auxiliary equipment driving apparatus for a vehicle engine in which
a one-way clutch-integrated pulley A according to a first
embodiment of the present invention is disposed. This auxiliary
equipment driving apparatus is provided at one end of a
four-cylinder four-cycle engine 20 mounted on an automotive
vehicle. The layout of this auxiliary equipment driving apparatus
is a so-called serpentine layout in which a single V-ribbed belt 23
as a power transmission belt is trained in a serpentined manner
among a drive pulley 21 mounted on a crank shaft 20a revolving with
slight variations in angular velocity due to an explosion stroke of
the engine 20 and a plurality of driven pulleys respectively
mounted on input shafts of a plurality of auxiliary equipment
including an alternator 22.
[0046] More specifically, as the above-mentioned driven pulleys, a
tension pulley 24 of an automatic belt tensioner, a pulley 25 for a
hydraulic pump of a power steering, an idler pulley 26, a pulley 27
for a compressor of an air conditioner, and a pulley 28 for an
engine-cooling fan are arranged, starting with the drive pulley 21,
in the order of such a running direction of the V-ribbed belt 23 as
shown in arrows in FIG. 5. In addition, the one-way
clutch-integrated pulley A is disposed between the tension pulley
24 of the automatic belt tensioner and the pulley 25 for a
hydraulic pump of a power steering, and is mounted on an alternator
shaft 22a of the alternator 22 in which inertial torque of a rotor
is relatively large.
[0047] As shown in FIG. 6, the one-way clutch-integrated pulley A
includes an inner ring 1 connected to the alternator shaft 22a and
an outer ring 2 coaxially disposed around the outer periphery of
the inner ring 1, and the inner and outer rings 1, 2 are relatively
rotatably assembled by a pair of bearings 3, 3 arranged between the
inner and outer rings 1, 2 at both sides in the axial direction
(both lateral sides in FIG. 6). Further, a pulley section 8 for
training the V-ribbed belt 23 therearound is fitted for unitary
rotation onto the outer periphery of the outer ring 2. Furthermore,
between both the bearings 3 and 3, a clutch mechanism 10 is
provided for effecting or blocking torque transmission between the
inner and outer rings 1, 2 according to the direction of relative
rotation of the inner and outer rings 1, 2.
[0048] Each bearing 3 is a deep-groove ball bearing, which includes
an annular bearing inner ring 4 fixedly fitted onto the outer
periphery of the inner ring 1 to unitarily rotate with the inner
ring 1 and an annular bearing outer ring 5 disposed coaxially
around the outer periphery of the bearing inner ring 4 and fixedly
fitted into the inner periphery of the outer ring 2 to unitarily
rotate with the outer ring 2. The outer periphery of the bearing
inner ring 4 and the inner periphery of the bearing outer ring 5
are provided throughout these peripheries with deep grooves 4a, 5a
of arcuate cross section, respectively. Further, an annular cage 6
is coaxially disposed between the bearing inner and outer rings 4,
5 and for relative rotation with the bearing inner and outer rings
4, 5. A plurality of steel balls 7, 7, . . . are retained by the
cage 6 at regular circumferential pitches. The steel balls 7, 7, .
. . roll circumferentially in the deep grooves 4a, 5a of the
bearing inner and outer rings 4, 5 to allow the inner and outer
rings 1, 2 to relatively rotate.
[0049] As also shown in FIGS. 1 to 4, the clutch mechanism 10
includes a ring-like cage 11 disposed between the inner and outer
rings 1, 2 for relative rotation with the inner and outer rings 1,
2 and a plurality of intermediate members 12, 12, . . . retained by
the cage 11 for rocking motion in a single plane orthogonal to the
axis of the inner and outer rings 1, 2. In the cage 11, a plurality
of retaining holes 11a, 11a, . . . of rectangular cross section cut
through the cage 11 in its radial direction are arranged at
predetermined circumferential pitches. The intermediate members 12,
12, . . . are accommodated for rocking motion in the retaining
holes 11a, 11a, . . . , respectively. Out of two circumferentially
opposed inner wall surfaces of each retaining hole 11a, one inner
wall surface (right-hand one in FIG. 4) is formed in a protruding
wall extending with cross section like letter inverted-V toward the
other inner wall surface (left-hand one in the same figure). In the
other inner wall surface, two recesses 13, 13 are juxtaposed to
align in the axial direction of the inner and outer rings 1, 2 and
so as to be open toward the one inner wall surface (rightward in
the figure) and radially outward (upward in the figure). Further,
at a location between the two recesses 13 and 13 and
circumferentially opposite to the one inner wall surface (left side
in the figure), a groove 14 open radially outward is provided to
extend in the axial direction. The bottom of the groove 14 is
located radially outward beyond the bottom surface of the recess
13. Each end of the groove 14 is open to the corresponding recess
13.
[0050] Each intermediate member 12 is formed in a bar and a
gourd-like section, and is disposed in parallel with the axis of
the inner and outer rings 1, 2 and so that the lengthwise direction
of the section thereof substantially matches the radial direction
of the inner and outer rings 1, 2. The lengthwise size is slightly
larger than the distance between both cam surfaces 1a and 2a of the
inner and outer rings 1 and 2, the surface of the intermediate
member 12 on the inner ring 1 side serves as a cam surface 12a
slidable on the cam surface 1a of the inner ring 1, and the surface
thereof on the outer ring 2 side serves as a cam surface 12b
slidable on the cam surface 2a of the outer ring 2. When each
intermediate member 12 rocks clockwise in FIG. 4, it wedges between
the inner and outer rings 1 and 2 so that the cam surfaces 12a and
12b of the intermediate member 12 are pressed against the cam
surfaces 1a and 2a of the inner and outer rings 1 and 2,
respectively. On the other hand, when each intermediate member 12
rocks counterclockwise in the same figure, the cam surfaces 12a and
12b thereof come into sliding contact with the cam surfaces 1a and
2a of the inner and outer rings 1 and 2, respectively. Further, out
of two surfaces located at both widthwise ends (both lateral sides
in FIG. 4) of the section of each intermediate member 12, the
surface on the side corresponding to the protruding wall of the
retaining hole 11a of the cage 11 (right side in the figure) is
recessed in the form of a V-groove having gently inclined surfaces,
and the top of the protruding wall is brought into line contact
with the bottom of the groove in the axial direction of the inner
and outer rings 1, 2. The intermediate member 12 thus rocks on the
contact portion as a fulcrum.
[0051] In the cage 11 of the clutch mechanism 10, a spring member
15 is placed for each intermediate member 12, and each intermediate
member 12 is pressed by the corresponding spring member 15 in the
direction to wedge between the inner and outer rings 1 and 2.
[0052] Furthermore, in the present embodiment, as shown in enlarged
manner in FIGS. 1 to 3, each spring member 15 includes a pair of
coil springs 15a, 15a which are juxtaposed to align in the axial
direction of the inner and outer rings 1, 2 and extend in a
direction to press the corresponding intermediate member 12,
retained at one ends thereof (left ends in FIG. 1: hereinafter
referred to as root ends) by the cage, and resiliently contacted at
the other ends (right ends in the figure: hereinafter referred to
as distal ends) with the intermediate member 12. Furthermore,
between both the root ends of the coil springs 15a and 15a, a
connecting portion 15b is provided for connecting both the root
ends together.
[0053] Specifically, the pair of coil springs 15a, 15a and the
connecting portion 15b of each spring member 15 are formed of a
single wire. In its formation, one coil spring 15a (lower one in
FIG. 2) is formed dextrally, while the other coil spring 15a (upper
one in the figure) is formed sinistrally. The root end of the
dextrally formed coil spring 15a and the root end of the
sinistrally formed coil spring 15a connect each other through a
wire portion extending substantially linearly along the axis of the
inner and outer rings 1 and 2. The above-mentioned connecting
portion 15b is constituted by the linear wire portion. The pair of
coil springs 15a, 15a are manufactured under the same
specifications such as the coil diameter and the effective number
of turns except for the turning direction. Accordingly, the spring
constants k.sub.1 of the two coil springs 15a, 15a are identical (
k.sub.1=a). In the present embodiment, the spring constant k.sub.1
of each coil spring 15a is identical with the spring constant
k.sub.2 of a coil spring in the case where a spring member is
formed of a single coil spring like the prior art (
k.sub.1=k.sub.2=a). In other words, the spring constant k' of the
conventional spring member is k'=k.sub.2=a.
[0054] Further, the root end of the dextral coil spring 15a is
accommodated in one (upper one in FIG. 2) of the pair of recesses
13, 13 corresponding to each retaining hole of the cage 11, while
the root end of the sinistral coil spring 15a is accommodated in
the other recess 13 (lower one in the figure). In this case, the
root end of each coil spring 15a is closely wound like the prior
art. Furthermore, the connecting portion 15b is accommodated in the
groove 14 of the cage 11, and both ends of the connecting portion
15b are placed in continuous spaces between the groove 14 and the
recesses 13 and 13, respectively. In this case, the distance
between both the coil springs 15a and 15a is set slightly smaller
than the thickness of a partition wall of the cage 11 which
separates both the recesses 13 and 13 from each other so that both
the coil springs 15a, 15a sandwich therebetween the partition wall
on both sides in the axial direction of the inner and outer rings
1, 2. The coil springs 15a, 15a are thereby held against
displacement at the corresponding root end sides.
[0055] Furthermore, the distal end turn of each coil spring 15a is
formed so that when the corresponding portion of the wire extends
circularly from the position proximate to the outer ring 2 toward
the position proximate to the inner ring 1, it terminates ahead of
the position proximate to the inner ring 1. The distal end portion
of the wire is thereby held against contact with the cam surfaces
1a, 2a of the inner and outer rings 1, 2.
[0056] Now, calculation will be made of the natural frequency f of
the spring member 15 with respect to each intermediate member 12 in
the one-way clutch-integrated pulley A having the above-described
construction. First, since the spring constant k.sub.1 of each coil
spring 15a is k.sub.1=a, the spring constant k of the spring member
15 formed of the two coil springs 15a and 15a is
k=k1+k1=a+a=2a
[0057] which is two times as large as the spring constant
(k'=k.sub.2=a) in the case where the spring member is formed of a
single coil spring like the prior art.
[0058] Therefore, the natural frequency F of the spring member 15
in the one-way clutch-integrated pulley A is
F=(1/2.pi.)(k/m).sup.1/2=(1/2.pi.)(2a/m).sup.1/2
[0059] (where m is the mass of the intermediate member 12).
[0060] On the other hand, the natural frequency F' of the
conventional spring member is
F'=(1/2.pi.)(k/m).sup.1/2=(1/2.pi.)(a/m).sup.1/2.
[0061] Accordingly, as expressed by the following formula, it can
be understood that the natural frequency F of the spring member 15
in the one-way clutch-integrated pulley A according to the present
embodiment is approximately 1.414 times as large as the natural
frequency F' of the conventional spring member.
F.div.F'={(1/2.pi.)(2a/m).sup.1/2}.div.{(1/2.pi.)(a/m).sup.1/2}=(2a/m).sup-
.1/2.div.(a/m).sup.1/2=(2).sup.1/2.apprxeq.1.414
[0062] According to the present embodiment, in disposing a one-way
clutch-integrated pulley A in a torque transmission path of
serpentine layout in which torque of a crank shaft 20a of a vehicle
engine 20 is transmitted to auxiliary equipment such as an
alternator 22 through a V-ribbed belt 23, the one-way
clutch-integrated pulley A uses, as a spring member 15 for pressing
each intermediate member 12 into wedging between inner and outer
rings 1 and 2, a spring member having a pair of coil springs 15a,
15a juxtaposed to the intermediate member 12. Therefore, even if
the size of each coil spring 15a in its operating direction is not
increased, the spring member can attain the spring constant two
times as large as that in the case where a spring member is formed
of a single coil spring like the prior art. This enhances response
to input torque accompanied with high-frequency angular velocity
variations in spite of excellent durability.
[0063] Further, since the pair of coil springs 15a, 15a are
integrally formed by connecting one ends of both the coil springs
15a, 15a through the connecting portion 15b, each coil spring 15a
can be restrained against rotation around the coil axis and can be
fixed at the one end by using the connecting portion 15b.
Accordingly, the coil springs 15a, 15a can make their pressing
conditions against the intermediate member 12 steady even when
subjected to centrifugal forces or vibrations due to high-speed
engine revolution, thereby enabling its pressing force to be
stabilized. Furthermore, integral configuration of the pair of coil
springs 15a, 15a suppresses increase in number of components in
spite of use of two coil springs 15a, 15a for each intermediate
member 12.
[0064] The above embodiment describes the one-way clutch-integrated
pulley A of the type which effects or blocks torque transmission
between the inner and outer rings 1 and 2 by rocking motion of each
intermediate member 12. However, the present invention is also
applicable to one-way clutch-integrated pulleys using intermediate
members of other types.
[0065] In the above embodiment, description has been made about the
case where a deep-groove ball bearing is used as the bearing 3
interposed between the inner and outer rings 1 and 2. However,
other types of bearings may be used instead and no special
limitations are imposed on the number and layout of bearings.
[0066] Further, the above embodiment describes the case where each
spring member 15 has two coil springs 15a, 15a. However, the number
of coil springs may be three or more.
[0067] Furthermore, in the above embodiment, the connecting portion
15b provided in each spring member 15 is formed substantially
linearly. However, the shape of the connecting portion can be
properly designed depending upon the mounting structure of the
spring member in the cage and the like.
[0068] Furthermore, the above embodiment describes the case where
the one-way clutch-integrated pulley A is disposed in the auxiliary
equipment driving apparatus for a vehicle engine. However, it goes
without saying that the pulley can be disposed in other torque
transmission paths.
[0069] In addition, the above embodiment describes the one-way
clutch-integrated pulley A as a built-in type one-way clutch in
which the pulley section 8 is fitted onto the outer ring 2.
However, the present invention is applicable to one-way clutches of
various types which press intermediate members in the direction of
wedging between inner and outer rings with spring members.
Experimental Example
[0070] Next, when the one-way clutch-integrated pulley A of the
above embodiment is used as an inventive example, an experiment
carried out for examining the delay angle thereof will be
described.
[0071] Specifically, as schematically shown in FIG. 7, a V-ribbed
belt 23 was trained between a drive pulley 31 of a V-ribbed pulley
and the one-way clutch-integrated pulley A, and in this arrangement
the drive pulley 31 was driven into rotation so that the one-way
clutch-integrated pulley A could input torque with a target speed
of 12500 rpm, a rate of variation of revolution of 3% and a
frequency of variations of 100 to 200 Hz. At the time, the speeds
of the outer and inner rings were measured. Then, the mean value of
delay angles was calculated based on the measured data. The above
speed and conditions of variation of revolution conform to angular
velocity variations of torque input to the one-way
clutch-integrated pulley A when the speed is 3000 to 6000 rpm in
the four-cycle four-cylinder engine. Further, the inner ring of the
one-way clutch-integrated pulley A is connected to an alternator
shaft of an alternator and a load of 120 A is placed on the
alternator. The changes of speed (unit: rpm) of the inner and outer
rings in this case are shown together in FIG. 8.
[0072] The calculated mean value of delay angles in the one-way
clutch-integrated pulley A under the above conditions was in the
order of slightly above 3.degree..
[0073] For comparison, using as a comparative example a
conventional one-way clutch-integrated pulley in which a spring
member for each intermediate member is formed of a single coil
spring, the same experiment was also carried out under the same
conditions as in the above case. The calculated mean value of delay
angles in the comparative example was in the order of slightly
above 4.degree.. The mean values of delay angles in these inventive
and comparative examples are shown together in FIG. 9.
[0074] As can be seen from the above, the inventive example is
about 1.degree. smaller in delay angle than the comparative
example.
Industrial Applicability
[0075] As described so far, the one-way clutch according to the
present invention is excellent in durability and attains excellent
response to high-frequency vibrations and therefore is also
suitable for use as a clutch operated at high speeds with, for
example, an automotive engine.
* * * * *