U.S. patent application number 14/428853 was filed with the patent office on 2015-09-03 for clutch.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Daisuke KOBAYASHI, Shintaro NAKANO, Masao NAKAYAMA, Hirotaka SUNADA, Hideki TSUTSUI. Invention is credited to Daisuke Kobayashi, Shintaro Nakano, Masao Nakayama, Hirotaka Sunada, Hideki Tsutsui.
Application Number | 20150247536 14/428853 |
Document ID | / |
Family ID | 50388265 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150247536 |
Kind Code |
A1 |
Sunada; Hirotaka ; et
al. |
September 3, 2015 |
CLUTCH
Abstract
A clutch is provided with a drive-side rotational body and a
driven-side rotational body, which is movable in the axial
direction of the drive-side rotational body between a coupled
position. The driven-side rotational body has a groove having a
helical portion and an annular portion. The clutch also includes an
urging member and a pin that is selectively inserted into and
retracted from the groove. The clutch moves the driven-side
rotational body to the decoupled position against the urging force
of the urging member by inserting the pin in the helical portion.
The clutch further includes a restricting portion that restricts
shifting of the position of the pin from the annular portion to the
helical portion when the pin is positioned in the annular
portion.
Inventors: |
Sunada; Hirotaka;
(Nagoya-shi, JP) ; Nakayama; Masao; (Nagoya-shi,
JP) ; Tsutsui; Hideki; (Yokkaichi-shi, JP) ;
Nakano; Shintaro; (Toyota-shi, JP) ; Kobayashi;
Daisuke; (Okazaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUNADA; Hirotaka
NAKAYAMA; Masao
TSUTSUI; Hideki
NAKANO; Shintaro
KOBAYASHI; Daisuke |
|
|
US
US
US
US
US |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi-ken
JP
|
Family ID: |
50388265 |
Appl. No.: |
14/428853 |
Filed: |
September 25, 2013 |
PCT Filed: |
September 25, 2013 |
PCT NO: |
PCT/JP2013/075874 |
371 Date: |
March 17, 2015 |
Current U.S.
Class: |
192/66.1 |
Current CPC
Class: |
F16D 27/108 20130101;
F16D 13/76 20130101; F16D 15/00 20130101; F16D 23/12 20130101; F16D
41/088 20130101; F16D 2023/123 20130101 |
International
Class: |
F16D 23/12 20060101
F16D023/12; F16D 27/108 20060101 F16D027/108; F16D 15/00 20060101
F16D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2012 |
JP |
2012-211046 |
Jul 25, 2013 |
JP |
2013-154986 |
Sep 19, 2013 |
JP |
2013-194686 |
Claims
1. A clutch comprising: a drive-side rotational body; a driven-side
rotational body movable in an axial direction of the drive-side
rotational body between a coupled position at which the driven-side
rotational body is coupled to the drive-side rotational body and a
decoupled position at which the driven-side rotational body is
decoupled from the drive-side rotational body; an urging member
that urges the driven-side rotational body from the decoupled
position toward the coupled position; a groove formed in an outer
circumferential surface of the driven-side rotational body, wherein
the groove has a helical portion that extends about an axis of the
driven-side rotational body and an annular portion that is formed
continuously from the helical portion and extends over an entire
circumference of the driven-side rotational body and
perpendicularly to the axial direction; a pin that is selectively
inserted into and retracted from the groove and restricted from
moving in the axial direction, wherein, when the pin is in a state
inserted in the helical portion and engaged with a side wall of the
helical portion, the position of the pin is shifted from the
helical portion to the annular portion through rotation of the
driven-side rotational body such that the driven-side rotational
body is moved to the decoupled position against urging force of the
urging member; and a restricting portion that restricts shifting of
the position of the pin from the annular portion to the helical
portion when the pin is in a state located in the annular
portion.
2. The clutch according to claim 1, wherein the helical portion is
a helical groove, the annular portion is an annular groove having a
depth greater than the depth of the helical groove, the groove
includes a step in a connecting portion by which the helical groove
and the annular groove are connected to each other, and a side wall
of the step functions as the restricting portion.
3. The clutch according to claim 1, wherein the helical portion is
a helical groove, the annular portion is an annular groove
including a connecting portion connected to the helical groove, and
the restricting portion includes a protrusion and a recess, wherein
the protrusion projects from a bottom surface of the annular groove
and extends at least over an entire length of the connecting
portion in the extending direction of the annular groove, and the
recess is formed at a distal end of the pin and becomes engaged
with the protrusion when the pin is arranged in the connecting
portion.
4. The clutch according to claim 1, wherein the helical portion is
a helical groove, the annular portion is an annular groove
including a connecting portion connected to the helical groove, and
the restricting portion includes a recessed groove and a
projection, wherein the recessed groove is formed in a bottom
surface of the annular groove and extends at least over an entire
length of the connecting portion in the extending direction of the
annular groove, and the projection projects from a distal end of
the pin and becomes engaged with the recessed groove when the pin
is arranged in the connecting portion.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a clutch that switches the
state of power transmission from a drive-side rotational body to a
driven-side rotational body by switching the coupling state of the
driven-side rotational body with respect to the drive-side
rotational body.
[0002] An engine is known that couples a mechanical pump, which
circulates coolant, to the crankshaft through a clutch to operate
the pump using rotational force of the crankshaft and disengages
the clutch to stop operation of the pump. Clutches for switching
the coupling state of the pump with respect to the crankshaft
include a clutch having a drive-side rotational body coupled to the
crankshaft and a driven-side rotational body, which is rotational
relative to the drive-side rotational body. The clutch is
maintained in the engaged state by pressing the rotational bodies
against each other using magnetic force of magnets.
[0003] Such clutches include a clutch described in Patent Document
1. The clutch described in Patent Document 1 includes a coil. To
disengage the clutch, energization control is performed on the coil
to generate a magnetic field that cancels the aforementioned
magnetic force.
PRIOR ART DOCUMENT
Patent Document
[0004] Patent Document 1: Japanese Laid-Open Patent Publication No.
2010-203406
SUMMARY OF THE INVENTION
[0005] Problems that the Invention is to Solve
[0006] In a configuration in which the clutch is maintained in the
engaged state by pressing the drive-side rotational body and the
driven-side rotational body against each other as described in
Patent Document 1, the force needed for such pressing becomes
greater as the torque that needs to be transmitted through the
clutch, or, in other words, the torque needed by an auxiliary
device driven and rotated by the driven-side rotational body,
becomes greater. To increase the pressing force, magnets with a
greater magnetic force must be employed. This necessitates a
larger-sized coil to cancel the magnetic force.
[0007] The larger-sized coil enlarges the size of the clutch and
increases power consumption. Therefore, the force needed for
disengagement is therefore desired to be minimized while ensuring
transmission of great torque.
[0008] This problem is not restricted to clutches that cancel
magnetic force of magnets by generating a magnetic field as in the
above-described case. The same problem is generally present in
clutches that are disengaged by causing relative movement between a
drive-side rotational body and a driven-side rotational body with
an actuator, such as clutches that are disengaged using hydraulic
pressure.
[0009] Accordingly, it is an objective of the present disclosure to
provide a clutch that can be disengaged by a small force.
Means for Solving the Problems
[0010] To achieve the foregoing objective and in accordance with
one aspect of the present invention, a clutch is provided that
includes a drive-side rotational body, a driven-side rotational
body, an urging member, a groove, a pin, and a restricting portion.
The driven-side rotational body is movable in an axial direction of
the drive-side rotational body between a coupled position at which
the driven-side rotational body is coupled to the drive-side
rotational body and a decoupled position at which the driven-side
rotational body is decoupled from the drive-side rotational body.
The urging member urges the driven-side rotational body from the
decoupled position toward the coupled position. The groove is
formed in an outer circumferential surface of the driven-side
rotational body. The groove has a helical portion that extends
about an axis of the driven-side rotational body and an annular
portion that is formed continuously from the helical portion and
extends over an entire circumference of the driven-side rotational
body and perpendicularly to the axial direction. The pin is
selectively inserted into and retracted from the groove and
restricted from moving in the axial direction. When the pin is in a
state inserted in the helical portion and engaged with a side wall
of the helical portion, the position of the pin is shifted from the
helical portion to the annular portion through rotation of the
driven-side rotational body such that the driven-side rotational
body is moved to the decoupled position against urging force of the
urging member. The restricting portion restricts shifting of the
position of the pin from the annular portion to the helical portion
when the pin is in a state located in the annular portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional view showing a clutch according
to a first embodiment;
[0012] FIG. 2 is a side view showing the clutch shown in FIG. 1 in
a disengaged state;
[0013] FIG. 3 is a side view showing the clutch of FIG. 1 in an
engaged state;
[0014] FIG. 4 is a cross-sectional view illustrating the
relationship between a groove of a driven-side rotational body and
a stopper member and the configuration of an actuator for operating
the stopper member;
[0015] FIG. 5 is a side view showing a clutch according to a second
embodiment in a disengaged state;
[0016] FIG. 6 is a side view showing the clutch illustrated in FIG.
5 in an engaged state;
[0017] FIG. 7 is a developed view showing a groove of the clutch of
FIG. 5;
[0018] FIG. 8 is a side view showing a clutch according to a third
embodiment in a disengaged state;
[0019] FIG. 9 is a side view showing the clutch illustrated in FIG.
8 in an engaged state;
[0020] FIG. 10 is a developed view showing a groove of the clutch
of FIG. 8;
[0021] FIG. 11 is a developed view showing a groove of a
modification of the third embodiment;
[0022] FIGS. 12A, 12B, 12C, and 12D are schematic diagrams
illustrating change of the state of a clutch according to a fourth
embodiment;
[0023] FIGS. 13A, 13B, 13C, and 13D are schematic diagrams
illustrating change of the state of a clutch according to a fifth
embodiment; and
[0024] FIG. 14 is a perspective view showing a driven-side
rotational body according to another embodiment.
MODES FOR CARRYING OUT THE INVENTION
First Embodiment
[0025] A clutch according to a first embodiment will now be
described with reference to FIGS. 1 to 4.
[0026] A clutch according to a first embodiment switches the state
of power transmission from a crankshaft arranged in an engine to a
water pump, which circulates coolant of the engine.
[0027] As shown in FIG. 1, a clutch 100 of the first embodiment is
accommodated in an accommodating portion 310, which is arranged in
a housing 300. A substantially cylindrical support member 320 is
fitted in the housing 300. An output shaft 210 of the clutch 100 is
rotationally supported by the support member 320 through a first
bearing 330, which is located at an inner circumferential side of
the support member 320.
[0028] An impeller 220 of a pump 200 is attached to a distal end
portion (a right end portion as viewed in FIG. 1) of the output
shaft 210 in a manner rotational integrally with the output shaft
210. A drive-side rotational body 110 is rotationally supported by
a proximal end portion (a left end portion as viewed in the
drawing) of the output shaft 210 through a second bearing 340. A
straight spline 212 is formed in an outer circumferential surface
of a portion of the output shaft 210 between the first bearing 330
and the second bearing 340.
[0029] With reference to FIG. 1, a driven-side rotational body 120
is arranged between the housing 300 and the drive-side rotational
body 110. An engagement portion 121, which is meshed with the
straight spline 212 of the output shaft 210, is formed in an inner
circumferential surface of the driven-side rotational body 120.
This configuration allows the driven-side rotational body 120 to
rotate integrally with the output shaft 210 and move in the axial
direction of the output shaft 210. In the first embodiment, as
represented by the long dashed short dashed lines in FIGS. 1 to 3,
the output shaft 210, the drive-side rotational body 110, and the
driven-side rotational body 120 are arranged coaxially with one
another. Hereinafter, the extending direction of the axis of these
components will be referred to as the axial direction.
[0030] The driven-side rotational body 120 has an outline including
two columns that have different diameters and are joined coaxially
with each other. The driven-side rotational body 120 is supported
by the output shaft 210 in such an orientation that a large
diameter portion 122 is located on the side close to the drive-side
rotational body 110 (a left side as viewed in FIG. 1) and a small
diameter portion 123 is arranged on the side close to the pump 200
(a right side as viewed in the drawing).
[0031] A recess 124 having an opening facing the pump 200 is formed
in the small diameter portion 123 of the driven-side rotational
body 120. A plurality of accommodating recesses 125 for
accommodating urging members 135 are formed in a bottom portion of
the recess 124. The accommodating recesses 125 are arranged
circumferentially in a manner surrounding the output shaft 210.
[0032] Each of the urging members 135 is, for example, a coil
spring and accommodated in the corresponding one of the
accommodating recesses 125. Each urging member 135 has a distal end
secured to a securing projection 211, which projects from the
output shaft 210. The urging members 135 are accommodated in the
corresponding accommodating recesses 125 each in a compressed state
and urge the driven-side rotational body 120 toward the drive-side
rotational body 110 (leftward as viewed in FIG. 1).
[0033] A plurality of ball accommodating grooves 127 each for
accommodating a corresponding one of balls 130 are formed in the
large diameter portion 122 of the driven-side rotational body 120
and arranged circumferentially. An arcuate groove 111, which
extends over the entire circumference of an inner circumferential
surface of the drive-side rotational body 110, is formed in the
inner circumferential surface of the drive-side rotational body
110. With reference to FIG. 1, the arcuate groove 111 has an
arcuate cross section. Each of the balls 130 is accommodated in the
space formed by the corresponding one of the ball accommodating
grooves 127 and the arcuate groove 111.
[0034] When the driven-side rotational body 120 is arranged at the
position illustrated in FIG. 1 after having been moved toward the
drive-side rotational body 110 by the urging force of the urging
members 135, the drive-side rotational body 110 and the driven-side
rotational body 120 are coupled to each other through the balls
130.
[0035] Hereinafter, out of axial positions of the driven-side
rotational body 120 moving axially along the output shaft 210, the
position at which the drive-side rotational body 110 and the
driven-side rotational body 120 are coupled to each other, as
illustrated in FIG. 1, will be referred to as a coupled
position.
[0036] A cup-like driven-side pulley 270, which surrounds the
clutch 100 accommodated in the accommodating portion 310 of the
housing 300, is attached to the drive-side rotational body 110. A
drive-side pulley 260 is attached to an end portion of the
crankshaft 250 in a manner rotational integrally with the
crankshaft 250. The drive-side pulley 260 and the driven-side
pulley 270 are coupled to each other through a belt 280, which is
looped over the drive-side pulley 260 and the driven-side pulley
270.
[0037] As a result, as illustrated in FIG. 1, when the driven-side
rotational body 120 is arranged at the coupled position and the
drive-side rotational body 110 and the driven-side rotational body
120 are coupled to each other through the balls 130, rotation of
the crankshaft 250 is transmitted to the driven-side rotational
body 120 and the output shaft 210 via the drive-side pulley 260 and
the belt 280. This causes the impeller 220, which rotates
integrally with the output shaft 210, to supply coolant out from
the pump 200. As represented by the arrows in FIGS. 2 and 3, the
drive-side rotational body 110 rotates in a clockwise direction as
viewed from the side corresponding to the distal end of the output
shaft 210 (the side corresponding to the right end as viewed in
FIGS. 2 and 3) toward the drive-side rotational body 110.
[0038] Referring to FIGS. 2 and 3, each of the ball accommodating
grooves 127, which are formed in the large diameter portion 122 of
the driven-side rotational body 120, extends in the axial direction
from an end surface of the large diameter portion 122 before being
curved and then extends in the rotational direction of the
drive-side rotational body 110. A finishing end of each ball
accommodating groove 127 forms a holding portion 128.
[0039] The depth of each ball accommodating groove 127 becomes
smaller in the rotational direction of the drive-side rotational
body 110 such that the depth of the holding portion 128 is
minimized.
[0040] As a result, as illustrated in FIG. 2, when each ball 130 is
accommodated in the axially extended portion of the corresponding
ball accommodating groove 127, a clearance in which the ball 130 is
permitted to rotate, together with the driven-side rotational body
120, with respect to the drive-side rotational body 110 is formed
between the ball accommodating groove 127 and the arcuate groove
111 (see FIG. 1) of the drive-side rotational body 110.
[0041] In contrast, as illustrated in FIG. 3, when each ball 130 is
located in the corresponding holding portion 128 after having been
moved in the ball accommodating groove 127, the clearance between
the holding portion 128 and the arcuate groove 111 (see FIG. 1) of
the drive-side rotational body 110 is small. The ball 130 is thus
caught between the driven-side rotational body 120 and the
drive-side rotational body 110. This restricts rotation of the ball
130 together with the driven-side rotational body 120 with respect
to the drive-side rotational body 110.
[0042] In this manner, the balls 130 are non-rotational when the
driven-side rotational body 120 is arranged at the coupled position
illustrated in FIG. 3. This allows the driven-side rotational body
120 to rotate together with the drive-side rotational body 110.
That is, when the driven-side rotational body 120 is located at the
coupled position, the balls 130 are caught between the driven-side
rotational body 120 and the drive-side rotational body 110 in a
non-rotational manner, thus coupling the driven-side rotational
body 120 to the drive-side rotational body 110.
[0043] In contrast, when the driven-side rotational body 120 is
arranged at the position illustrated in FIG. 2, the balls 130 are
released from the holding portions 128 and received in the axially
extended portions of the corresponding ball accommodating grooves
127. Specifically, a substantially half of each ball 130 is
accommodated in the arcuate groove 111 of the drive-side rotational
body 110. This restricts axial movement of the ball 130 relative to
the drive-side rotational body 110. When each ball 130 is received
in the axially extended portion, which has a depth greater than the
depth of each holding portion 128, after having been released from
the holding portion 128 with a smaller depth, the ball 130 is
released from the driven-side rotational body 120 and the
drive-side rotational body 110. As a result, the drive-side
rotational body 110 and the driven-side rotational body 120 are
allowed to rotate relative to each other. That is, the driven-side
rotational body 120 is decoupled from the drive-side rotational
body 110.
[0044] Hereinafter, out of the axial positions of the driven-side
rotational body 120 moving axially along the output shaft 210, the
position at which the drive-side rotational body 110 and the
driven-side rotational body 120 are decoupled from each other as
illustrated in FIG. 2 will be referred to as a decoupled
position.
[0045] As illustrated in FIG. 2, a circumferential groove 400 is
formed in an outer circumferential surface of the small diameter
portion 123 of the driven-side rotational body 120. The groove 400
includes a helical groove 410 serving as a helical portion
extending about the axis in a manner inclined with respect to the
axial direction and an annular groove 420 serving as an annular
portion extending perpendicular to the axial direction. The helical
groove 410 extends in a manner revolving on the outer
circumferential surface of the driven-side rotational body 120 by
one cycle and inclined such that the helical groove 410 approaches
the drive-side rotational body 110 toward the trailing end in the
rotational direction of the drive-side rotational body 110. The
annular groove 420 is formed continuously from the helical groove
410 and extends over the entire circumference of the outer
circumferential surface of the driven-side rotational body 120. The
configuration of the groove 400 will be described in detail
below.
[0046] With reference to FIGS. 2 and 3, the clutch 100 includes a
locking member 140 and an actuator 150 for selectively inserting
and retracting a pin 141, which is arranged at the distal end of
the locking member 140, with respect to the groove 400. The axial
position of the locking member 140 is restricted. As illustrated in
FIG. 3, the axial position of the locking member 140 is set such
that the pin 141 is inserted into a portion of the helical groove
410 of the groove 400 in the vicinity of a starting end 411 when
the driven-side rotational body 120 is arranged at the coupled
position. If the locking member 140 is operated by the actuator 150
to move toward the driven-side rotational body 120 when the
driven-side rotational body 120 is located at the coupled position,
the pin 141 is inserted into the portion of the helical groove 410
in the vicinity of the starting end 411. After having been inserted
into the helical groove 410, the pin 141 is engaged with a side
wall 413 of the helical groove 410, thus locking the driven-side
rotational body 120 against the urging force of the urging members
135.
[0047] If the pin 141 of the locking member 140 is inserted into
the helical groove 410 when the driven-side rotational body 120 is
coupled to the drive-side rotational body 110, the driven-side
rotational body 120 is rotated with the pin 141 engaged with the
side wall 413 of the helical groove 410. Then, while the pin 141
slides on the side wall 413 of the helical groove 410, the
driven-side rotational body 120 moves axially from the coupled
position toward the decoupled position. When the pin 141 reaches a
finishing end 412 of the helical groove 410, the pin 141 is
inserted into the annular groove 420 and the driven-side rotational
body 120 is switched from the coupled position to the decoupled
position. As has been described, the clutch 100 is configured such
that, by inserting the pin 141 of the looking member 140 into the
groove 400 to engage the pin 141 with the side wall 413 of the
helical groove 410, the driven-side rotational body 120 is moved to
the decoupled position against the urging force of the urging
members 135.
[0048] When the drive-side rotational body 110 and the driven-side
rotational body 120 are decoupled from each other, torque
transmission from the drive-side rotational body 110 to the
driven-side rotational body 120 is stopped. However, immediately
after such decoupling, the driven-side rotational body 120 is
continuously rotated by inertial force. Specifically, when the
driven-side rotational body 120 is located at the decoupled
position, the pin 141 is inserted in the annular groove 420, which
extends over the entire circumference of the driven-side rotational
body 120. The driven-side rotational body 120 is thus prohibited
from shifting axially. In this state, since torque transmission
from the drive-side rotational body 110 to the driven-side
rotational body 120 is stopped, the rotational speed of the
driven-side rotational body 120 gradually decreases and such
rotation eventually stops.
[0049] The driven-side rotational body 120 is urged toward the
coupled position by the urging force of the urging members 135.
Accordingly, to maintain the decoupled state, the pin 141 of the
locking member 140 must be maintained in a state inserted in the
annular groove 420 of the driven-side rotational body 120. To
re-couple the drive-side rotational body 110 and the driven-side
rotational body 120 to each other, the pin 141 is retracted from
the annular groove 420 of the groove 400 by means of the actuator
150. After the pin 141 is retracted in this manner, the locking
member 140 is disengaged from the driven-side rotational body 120
and the driven-side rotational body 120 is moved to the coupled
position by the urging force of the urging members 135. As a
result, the drive-side rotational body 110 and the driven-side
rotational body 120 are returned to the coupled state.
[0050] In the groove 400 formed in the outer circumferential
surface of the driven-side rotational body 120, the annular groove
420 is formed continuously from the helical groove 410 and extends
over the entire circumference of the outer circumferential surface
of the driven-side rotational body 120. The groove 400 of the
driven-side rotational body 120 thus has a connecting portion at
which the annular groove 420 and the helical groove 410 are
connected to each other. Therefore, when the pin 141 is inserted in
the annular groove 420 such that the driven-side rotational body
120 is located at the decoupled position but the driven-side
rotational body 120 is continuously rotated by inertial force, the
pin 141 is possibly shifted to the helical groove 410 through the
connecting portion between the helical groove 410 and the annular
groove 420. To avoid this, the clutch 100 of the first embodiment
includes a restricting portion, which restricts such shifting of
the pin 141 from the annular groove 420 to the helical groove 410
when the pin 141 is inserted in the annular groove 420.
[0051] The restricting portion is configured in the manner
described below. That is, in the groove 400, as illustrated in
FIGS. 2 to 4, the annular groove 420 has a depth greater than the
depth of the helical groove 410. In other words, the bottom surface
of the annular groove 420 is located radially inward of the bottom
surface of the helical groove 410. The annular groove 420 and the
helical groove 410 are thus connected together with a step formed
between the annular groove 420 and the helical groove 410. In the
first embodiment, the step, which is the side wall 423 of the
annular groove 420, functions as the restricting portion.
[0052] With reference to FIGS. 2 and 3, the width of the helical
groove 410 becomes gradually smaller from the starting end 411 to
the finishing end 412. Therefore, when the inserting position of
the pin 141, which has been inserted into the portion of the
helical groove 410 in the vicinity of the starting end 411, reaches
the finishing end 412 of the helical groove 410 as the driven-side
rotational body 120 rotates, the pin 141 is pressed by the side
wall 413 of the helical groove 410 and thus inserted into the
annular groove 420, which has a depth greater than the depth of the
helical groove 410.
[0053] Further, as illustrated in FIG. 4, the depth of the helical
groove 410 becomes gradually greater from the starting end 411 to
the finishing end 412. In other words, the radial position of the
bottom surface of the helical groove 410 approaches the axis of the
driven-side rotational body 120 gradually from the starting end 411
to the finishing end 412. The depth of the annular groove 420 is
small at the starting end 421 of the annular groove 420, which
corresponds to the finishing end 412 of the helical groove 410,
relative to the depths of the other portions in the circumferential
direction of the driven-side rotational body 120. The radial
distance between the bottom surface of the annular groove 420 and
the bottom surface of the helical groove 410 is thus small at the
portion corresponding to the finishing end 412 of the helical
groove 410 and the starting end 421 of the annular groove 420,
relative to other portions. That is, at this portion, the step
between the helical groove 410 and the annular groove 420 is
relatively small. This attenuates impact applied to the pin 141
when the pin 141 reaches the finishing end 412 of the helical
groove 410 and is then inserted into the annular groove 420, which
has a depth greater than the depth of the helical groove 410,
compared to a case in which the size of the step is set uniform in
the circumferential direction. Specifically, the step at the
aforementioned portion is set to such a size that the
aforementioned impact is attenuated and shifting of the pin 141
from the annular groove 420 to the helical groove 410 is
restrained.
[0054] The structure of the actuator 150 will now be described.
[0055] As illustrated in FIG. 4, the actuator 150 of the first
embodiment is an electromagnetic actuator, which is operated
through action of a magnetic field generated by energizing a coil
153 accommodated in a first case 152.
[0056] The first case 152 has a cylindrical shape having a bottom
portion and a fixed core 154 is fixed to the bottom portion. The
coil 153 is arranged in the first case 152 to surround the fixed
core 154. That is, in the actuator 150, the fixed core 154 and the
coil 153 configure an electromagnet. A movable core 155 is movably
accommodated in the coil 153 of the first case 152 at a position
facing the fixed core 154. The fixed core 154 and the movable core
155 of the first embodiment are both iron cores.
[0057] A cylindrical second case 158 is fixed to a distal end
portion (a right end portion as viewed in FIG. 4) of the first case
152. A permanent magnet 159 is fixed to an end portion of the
second case 158 fixed to the first case 152 in a manner surrounding
the movable core 155. As has been described, the movable core 155
is accommodated in the first case 152 such that a proximal end zone
(a left end zone as viewed in FIG. 4) of the movable core 155 faces
the fixed core 154. A distal end zone (a right end zone as viewed
in the drawing) projects outward from the second case 158.
[0058] A ring member 160 is attached to the portion of the movable
core 155 that is accommodated in the second case 158. A coil spring
161, which has an end secured to the second case 158 and an
opposite end secured to the ring member 160, is accommodated in the
second case 158 in a compressed state.
[0059] The coil spring 161 urges the movable core 155 in the
direction in which the movable core 155 projects from the second
case 158 (rightward as viewed in FIG. 4). The portion of the
movable core 155 that projects from the second case 158 is coupled
to the locking member 140 through a fixing pin 162.
[0060] The locking member 140 is pivotally coupled to the movable
core 155 at the proximal end of the locking member 140 and
pivotally supported by a pivot shaft 156. This allows the locking
member 140 to pivot about the pivot shaft 156, which is a support
point of pivot, when the movable core 155 moves. As a result, as
represented by the solid lines in FIG. 4, as the extent of
projection of the movable core 155 from the second case 158 is
increased by the urging force of the coil spring 161, the pin 141
of the locking member 140 is inserted sequentially into the helical
groove 410 and the annular groove 420 of the driven-side rotational
body 120.
[0061] If the coil 153 is energized in this state, a magnetic field
is generated through such energization to magnetize the fixed core
154 and the movable core 155. The movable core 155 is thus
attracted to the fixed core 154 against the urging force of the
coil spring 161. The direction of the magnetic field generated by
the coil 153 at this stage matches with the direction of the
magnetic field generated by the permanent magnet 159.
[0062] As the movable core 155 is attracted and moved toward the
fixed core 154 (leftward as viewed in FIG. 4), the locking member
140 is pivoted clockwise as viewed in FIG. 4 to retract the distal
end of the locking member 140 from the groove 400. That is, the
actuator 150 retracts the locking member 140 from the groove 400 by
attracting the movable core 155 using magnetic force produced
through energization of the coil 153.
[0063] After the movable core 155 is attracted and moved to a
contact position at which the movable core 155 contacts the fixed
core 154 (the position represented by the long dashed double-short
dashed lines in FIG. 4), the movable core 155 is held in contact
with the fixed core 154 by the magnetic force of the permanent
magnet 159 even if the energization is stopped afterwards.
[0064] In contrast, if the coil 153 is energized by an electric
current flowing in the opposite direction to the direction of the
electric current for attracting the movable core 155 when the
movable core 155 is arranged at the contact position represented by
the long dashed double-short dashed lines in FIG. 4, a magnetic
field is generated in the opposite direction to the direction of
the magnetic field of the permanent magnet 159. This attenuates the
attracting force of the permanent magnet 159, and the movable core
155 is separated from the fixed core 154 by the urging force of the
coil spring 161. The movable core 155 then moves to the projected
position represented by the solid lines in FIG. 4. As the movable
core 155 is moved from the contact position to the projected
position, the locking member 140 is pivoted counterclockwise as
viewed in FIG. 4 and the pin 141 of the locking member 140 is
inserted into the groove 400.
[0065] When the movable core 155 is located at the projected
position at which the movable core 155 is separated from the fixed
core 154, the urging force of the coil spring 161 exceeds the
attracting force of the permanent magnet 159. As a result, if the
coil 153 is energized to separate the movable core 155 from the
fixed core 154, the movable core 155 is held at the projected
position even after such energization is stopped afterward.
[0066] That is, the actuator 150 of the first embodiment is a
self-holding type solenoid, which switches the engagement state of
the clutch 100 by applying direct electric currents in different
directions and thus moving the movable core 155 and does not need
the energization to maintain the clutch 100 in either the engaged
state or the disengaged state.
[0067] Operation of the clutch 100 according to the present
embodiment will now be described.
[0068] As represented by the long dashed double-short dashed lines
in FIG. 4, when the movable core 155 of the actuator 150 is
arranged at the contact position, the pin 141 of the locking member
140 is located in the exterior of the groove 400. At this stage,
the driven-side rotational body 120 is held at the coupled position
by the urging force of the urging members 135 such that the clutch
100 is in the engaged state. That is, the clutch 100 transmits
rotation of the drive-side rotational body 110 to the output shaft
210.
[0069] If, in this state, the coil 153 of the actuator 150 is
energized to generate a magnetic field in the opposite direction to
the direction of the magnetic field of the permanent magnet 159,
the movable core 155 is moved from the contact position to the
projected position represented by the solid lines in FIG. 4 by the
urging force of the coil spring 161. This pivots the locking member
140 counterclockwise as viewed in FIG. 4, thus inserting the pin
141 of the locking member 140 into the portion of the helical
groove 410 of the groove 400 of the driven-side rotational body in
the vicinity of the starting end 411. The driven-side rotational
body 120 is thus stopped and held in the state illustrated in FIG.
3.
[0070] When the driven-side rotational body 120 is rotated together
with the drive-side rotational body 110 with the pin 141 locking
the driven-side rotational body 120 and the pin 141 is moved
relatively in the helical groove 410, the driven-side rotational
body 120 is moved from the coupled position to the decoupled
position and thus switched from the state illustrated in FIG. 3 to
the state illustrated in FIG. 2. In this manner, the pin 141 is
switched to a state inserted in the annular groove 420 and the
driven-side rotational body 120 reaches the decoupled position.
This stops transmission of rotation of the drive-side rotational
body 110 to the driven-side rotational body 120, thus disengaging
the clutch 100.
[0071] Immediately after the driven-side rotational body 120 and
the drive-side rotational body 110 are disengaged from each other,
the driven-side rotational body 120 is continuously rotated by
inertial force while receiving action of friction force produced
between the driven-side rotational body 120 and the pin 141, which
is inserted in the annular groove 420 as shown in FIG. 2. When the
pin 141 is inserted in the annular groove 420 and the driven-side
rotational body 120 is rotating, the pin 141 is engaged with the
step in the boundary between the helical groove 410 and the annular
groove 420, which is the side wall 423 of the annular groove 420.
Therefore, unless the pin 141 is shifted to be retracted from the
annular groove 420 and thus move past the step, the pin 141 cannot
be shifted into the helical groove 410, so that shifting of the pin
141 from the annular groove 420 into the helical groove 410 is
restricted. In this manner, the driven-side rotational body 120 is
rotated with the pin 141 of the locking member 140 inserted in the
annular groove 420 of the driven-side rotational body 120. The
rotational speed of the driven-side rotational body 120 then
decreases gradually until the driven-side rotational body 120
eventually stops rotating.
[0072] To switch the clutch 100 from the disengaged state to the
engaged state, the coil 153 of the actuator 150 is energized to
generate a magnetic field in the same direction as the direction of
the magnetic field of the permanent magnet 159. The movable core
155 is thus attracted toward the fixed core 154 by magnetic force
produced by energization and moved from the projected position
represented by the solid lines in FIG. 4 to the contact position
represented by the long dashed double-short dashed lines in the
drawing. This pivots the locking member 140 clockwise as viewed in
FIG. 4, thus fully retracting the pin 141 of the locking member 140
from the groove 400.
[0073] After having been released from the locking member 140, the
driven-side rotational body 120 is moved to the coupled position by
the urging force of the urging members 135. The driven-side
rotational body 120 and the drive-side rotational body 110 thus
become coupled to each other, switching the clutch 100 to the
engaged state.
[0074] The above described embodiment provides the following
advantages.
[0075] (1) In the first embodiment, when the pin 141 of the locking
member 140 is inserted in the helical portion of the driven-side
rotational body 120, the driven-side rotational body 120 is rotated
with the pin 141 engaged with the side wall 413 of the helical
portion. This moves the driven-side rotational body 120 from the
coupled position to the decoupled position against the urging force
of the urging members 135. In this manner, the force needed to
disengage the clutch 100 is obtained from the rotational force of
the driven-side rotational body 120. As a result, the drive-side
rotational body 110 and the driven-side rotational body 120 are
disengaged from each other by small force.
[0076] (2) In the first embodiment, when the pin 141 is inserted in
the annular groove 420, the pin 141 is engaged with the side wall
423 at the step in the boundary between the helical groove 410 and
the annular groove 420. Therefore, unless the pin 141 is shifted to
be retracted from the annular groove 420 and moves past the step,
the pin 141 cannot be shifted to the helical groove 410. That is,
when the pin 141 is inserted in the annular groove 420, the side
wall 423 at the step in the boundary between the helical groove 410
and the annular groove 420 functions as a restricting portion. This
restricts shifting of the pin 141 from the annular groove 420 to
the helical groove 410, thus restraining shifting of the
driven-side rotational body 120 to the coupled position despite the
fact that the pin 141 is maintained in the groove 400.
[0077] (3) In the first embodiment, the depth of the annular groove
420 is small in the vicinity of the starting end 421 relative to
the depths of the other portions in the circumferential direction
of the driven-side rotational body 120. The depth of the helical
groove 410 becomes gradually greater from the starting end 411 to
the finishing end 412. The step between the finishing end 412 of
the helical groove 410 and the starting end 421 of the annular
groove 420 is small-sized relative to steps in other portions. This
attenuates impact applied to the pin 141 when the pin 141 is moved
from the helical groove 410 and inserted into the annular groove
420, the depth of which is greater than the depth of the helical
groove 410, compared to a case in which the step between the
annular groove 420 and the helical groove 410 is set to a uniform
size in the circumferential direction of the driven-side rotational
body 120.
Second Embodiment
[0078] A clutch according to a second embodiment will now be
described with reference to FIGS. 5 to 7.
[0079] As illustrated in FIG. 5, a clutch 500 of the second
embodiment is different from the first embodiment in terms of the
configuration of a groove 520 formed in an outer circumferential
surface of a small diameter portion 511 of a driven-side rotational
body 510 and the configuration of a pin 560 of a locking member
550. The remainder of the configuration is the same as those of the
first embodiment. Thus, like or the same reference numerals are
given to those components that are like or the same as the
corresponding components of the first embodiment and detailed
explanations are omitted.
[0080] In the second embodiment, the groove 520 of the driven-side
rotational body 510 has a helical groove 530 inclined with respect
to the axial direction and an annular groove 540, which is formed
continuously from the helical groove 530 and extends over the
entire circumference of an outer circumferential surface of the
driven-side rotational body 510 and perpendicularly to the axial
direction.
[0081] With reference to FIGS. 5 to 7, the annular groove 540 has a
connecting portion 541, which has a depth equal to the depth of the
helical groove 530 and is connected to the helical groove 530, and
a non-connecting portion 542, which is disconnected from the
helical groove 530. In FIGS. 5 to 7, the boundary between the
connecting portion 541 of the annular groove 540 and the helical
groove 530 is represented by the long dashed double-short dashed
line. The long dashed double-short dashed line representing the
boundary coincides with the extended line of a side wall 544 of the
non-connecting portion 542 of the annular groove 540.
[0082] A protrusion 543, which protrudes from the bottom surface of
the annular groove 540 and extends in the extending direction of
the annular groove 540, is formed in the annular groove 540. The
protrusion 543 is formed over the entire length of the connecting
portion 541. The opposite ends of the protrusion 543 are arranged
in the non-connecting portion 542. The protrusion 543 of the
annular groove 540 has a uniform width and is inclined with respect
to the axial direction of the driven-side rotational body 510 by
the inclination angle equal to the inclination angle of a side wall
531 of the helical groove 530. As a result, with reference to FIG.
7, the distance from the side wall 531 of the helical groove 530 to
the protrusion 543 is a uniform distance d1 in the circumferential
direction of the driven-side rotational body 510.
[0083] As shown in FIGS. 5 to 7, a recess 561, into which the
protrusion 543 can proceed, is formed at the distal end of the pin
560 of the locking member 550. In FIG. 7, states of relative
movement of the pin 560 of the locking member 550 in the groove 520
when the driven-side rotational body 510 is in a rotating state are
illustrated by way of pins 560 represented by the long dashed
double-short dashed lines. In the second embodiment, the protrusion
543, which projects from the bottom surface of the annular groove
540, and the recess 561 of the pin 560 configure a restricting
portion.
[0084] Referring to FIG. 7, the width d2 of the pin 560 of the
locking member 550 is slightly smaller than the distance d1 from
the side wall 531 of the helical groove 530 to the protrusion 543.
The distance d3 from a starting end of the protrusion 543, which is
the end portion of the protrusion 543 that the pin 560 reaches
first when the driven-side rotational body 510 is rotated, to the
side wall 544 of the annular groove 540 is substantially equal to
but slightly greater than the length d4 from the side surface of
the pin 560 to the recess 561. The width d5 of the recess 561 is
greater than the width d6 of the protrusion 543.
[0085] Operation of the present embodiment will now be
described.
[0086] As illustrated in FIG. 6, when the driven-side rotational
body 510 is in a state coupled to the drive-side rotational body
110, the actuator 150 is operated to insert the pin 560 of the
locking member 550 into a starting end 532 of the helical groove
530 of the groove 520. This engages the pin 560 with the side wall
531 of the helical groove 530 to locks the driven-side rotational
body 120 against the urging force of the urging members 135. Then,
as the driven-side rotational body 510 is rotated, the pin 560 is
moved relatively in the groove 520 in a circumferential direction
while being engaged with the side wall 531 of the helical groove
530. The width d2 of the pin 560 is slightly smaller than the
distance d1 from the side wall 531 of the helical groove 530 to the
protrusion 543. This restrains interference of the protrusion 543
with movement of the pin 560 when the pin 560 is engaged with the
side wall 531 of the helical groove 530 and moved relatively in the
groove 520, thus allowing relative movement of the pin 560 in the
helical groove 530. The pin 560 thus reaches the annular groove 540
and is then moved relatively in the annular groove 540 of the
groove 520 as the driven-side rotational body 510 is rotated. The
driven-side rotational body 510 is rotated by inertial force at the
decoupled position.
[0087] As has been described, the distance d3 from the starting end
of the protrusion 543 to the side wall 544 of the annular groove
540 is substantially equal to but slightly greater than the length
d4 from the side wall of the pin 560 to the recess 561. The width
d5 of the recess 561 is greater than the width d6 of the protrusion
543. Therefore, when the driven-side rotational body 510 is rotated
and the pin 560 is moved relatively in the annular groove 540 to
reach the starting end of the protrusion 543, which is arranged in
the annular groove 540, the protrusion 543 proceeds into the recess
561 and becomes engaged with the recess 561. The protrusion 543
extends in the extending direction of the annular groove 540 and is
formed over the entire length of the connecting portion 541. As a
result, even if the driven-side rotational body 510 is rotated by
inertial force and the pin 560 is moved to the connecting portion
541 of the annular groove 540 such that the pin 560 and the side
surface of the groove 520, which is the side wall 544 of the
annular groove 540 corresponding to the non-connecting portion 542,
become separate from each other, the pin 560 is engaged with the
protrusion 543 and thus held in the annular groove 540.
[0088] To switch the clutch 500 from the disengaged state to the
engaged state, the actuator 150 is operated to retract the pin 560
of the locking member 550 from the annular groove 540 of the groove
520. This also causes disengagement between the recess 561 of the
pin 560 and the protrusion 543 of the annular groove 540. By
retracting the pin 560 of the locking member 550 from the groove
520 in this manner, the driven-side rotational body 510 is moved to
the coupled position by the urging force of the urging members 135.
The driven-side rotational body 510 and the drive-side rotational
body 110 thus become coupled to each other, switching the clutch
500 to the engaged state.
[0089] The second embodiment achieves the following advantage (4)
as well as an advantage equivalent to the advantage (1) of the
first embodiment.
[0090] (4) In the second embodiment, shifting of the pin 560 from
the annular groove 540 to the helical groove 530 is restricted
unless the pin 560 is shifted to be retracted from the annular
groove 540 and the recess 561 of the pin 560 and the protrusion 543
of the annular groove 540 are disengaged from each other. That is,
when the pin 560 is inserted in the annular groove 540, the recess
561 of the pin 560 and the protrusion 543 of the annular groove 540
function as a restricting portion. Therefore, since shifting of the
pin 560 from the annular groove 540 to the helical groove 530 is
restricted, it is possible to restrain shifting of the driven-side
rotational body 510 to the coupled position despite the fact that
the pin 560 is maintained in the groove 520.
Third Embodiment
[0091] A clutch according to a third embodiment will now be
described with reference to FIGS. 8 to 10.
[0092] As illustrated in FIG. 8, a clutch 600 of the third
embodiment is different from the illustrated embodiments in terms
of the configuration of a groove 620 formed in an outer
circumferential surface of a small diameter portion 611 of a
driven-side rotational body 610 and the configuration of a pin 660
of a locking member 650. The remainder of the configuration is the
same as those of the first embodiment. Thus, like or the same
reference numerals are given to those components that are like or
the same as the corresponding components of the first embodiment
and detailed explanations are omitted.
[0093] In the third embodiment, the groove 620 of the driven-side
rotational body 610 has a helical groove 630 inclined with respect
to the axial direction and an annular groove 640, which is formed
continuously from the helical groove 630 and extends over the
entire circumference of an outer circumferential surface of the
driven-side rotational body 610 and perpendicularly to the axial
direction.
[0094] As illustrated in FIGS. 8 to 10, the annular groove 640 has
a connecting portion 641, which has a depth equal to the depth of
the helical groove 630 and is connected directly to the helical
groove 630, and a non-connecting portion 642, which is not
connected directly to the helical groove 630. In FIGS. 8 to 10, the
boundary between the connecting portion 641 of the annular groove
640 and the helical groove 630 is represented by the long dashed
double-short dashed line. The long dashed double-short dashed line
representing the boundary coincides with the extended line of a
side wall 644 of the non-connecting portion 642 of the annular
groove 640.
[0095] A recessed groove 643, which extends in the extending
direction of the annular groove 640, is formed in the annular
groove 640. Specifically, the recessed groove 643 extends in a
direction perpendicular to the axial direction of the driven-side
rotational body 610. Also, the recessed groove 643 extends over the
entire length of the annular groove 640. That is, the recessed
groove 643 is formed over the entire circumference of the outer
circumferential surface of the driven-side rotational body 610.
[0096] With reference to FIGS. 8 to 10, a projection 661, which can
be inserted into the recessed groove 643, projects from the distal
end of the pin 660 of the locking member 650. In FIG. 10, states of
relative movement of the pin 660 of the locking member 650 in the
groove 620 when the driven-side rotational body 610 is in a
rotating state are illustrated by pins 660 represented by the long
dashed double-short dashed lines. In the third embodiment, the
recessed groove 643, which is formed in the bottom surface of the
annular groove 640, and the projection 661 of the pin 660 configure
a restricting portion.
[0097] Referring to FIG. 10, the length d1 from the side surface of
the pin 660 of the locking member 650 to the projection 661 is
substantially equal to but slightly greater than the distance d2
from the side wall 644 of the annular groove 640 to the recessed
groove 643. The width d3 of the projection 661 of the pin 660 is
smaller than the width d4 of the recessed groove 643 of the annular
groove 640.
[0098] Operation of the present embodiment will now be
described.
[0099] As illustrated in FIG. 9, when the driven-side rotational
body 610 is in a state coupled to the drive-side rotational body
110, the actuator 150 is operated to insert the pin 660 of the
locking member 650 into a starting end 632 of the helical groove
630 of the groove 620. This engages the pin 660 with a side wall
631 of the helical groove 630 to lock the driven-side rotational
body 120 against the urging force of the urging members 135. Then,
as the driven-side rotational body 610 is rotated, the pin 660 is
moved relatively in the groove 620 in a circumferential direction
while being engaged with the side wall 631 of the helical groove
630. The pin 660 thus reaches the annular groove 640 and the
driven-side rotational body 610 is moved to a decoupled position
and rotated by inertial force. As a result, with reference to FIG.
8, the pin 660 is switched to a state moving relatively in the
annular groove 640.
[0100] As has been described, the length d1 from the side surface
of the pin 660 of the locking member 650 to the projection 661 is
substantially equal to but slightly greater than the distance d2
from the side wall 644 of the annular groove 640 to the recessed
groove 643. The width d3 of the projection 661 of the pin 660 is
smaller than the width d4 of the recessed groove 643 of the annular
groove 640. Therefore, when the driven-side rotational body 610 is
rotated and the pin 660 is moved relatively in the annular groove
640, the projection 661 of the pin 660 proceeds into the recessed
groove 643, which is formed in the annular groove 640, and becomes
engaged with the recessed groove 643. The recessed groove 643
extends in the extending direction of the annular groove 640 and is
formed over the entire length of the annular groove 640. As a
result, even if the driven-side rotational body 610 is rotated by
inertial force and the pin 660 is moved to the connecting portion
641 of the annular groove 640 such that the pin 660 and the side
surface of the groove 620, which is the side wall 644 of the
annular groove 640 corresponding to the non-connecting portion 642,
become separate from each other, the projection 661 of the pin 660
is engaged with the recessed groove 643. The pin 660 is thus
maintained in the annular groove 640.
[0101] To switch the clutch 600 from the disengaged state to the
engaged state, the actuator 150 is operated to retract the pin 660
of the locking member 650 from the annular groove 640 of the groove
620. This also causes retraction of the projection 661 of the pin
660 from the recessed groove 643 of the annular groove 640, thus
disengaging the projection 661 of the pin 660 and the recessed
groove 643 of the annular groove 640 from each other. The
driven-side rotational body 510 is then moved to the coupled
position by the urging force of the urging members 135. As a
result, the driven-side rotational body 510 and the drive-side
rotational body 110 become coupled to each other, thus switching
the clutch 500 to the engaged state.
[0102] The third embodiment achieves the following advantage (5) as
well as an advantage equivalent to the advantage (1) of the first
embodiment.
[0103] (5) In the third embodiment, shifting of the pin 660 from
the annular groove 640 to the helical groove 630 is restricted
unless the pin 660 is shifted to be retracted from the annular
groove 640 and the recessed groove 643 and the projection 661 of
the pin 660 are disengaged from each other. That is, when the pin
660 is inserted in the annular groove 640, the recessed groove 643
and the projection 661 of the pin 660 function as a restricting
portion. As a result, since shifting of the pin 660 from the
annular groove 640 to the helical groove 630 is restricted, it is
possible to restrain shifting of the driven-side rotational body
610 to the coupled position despite the fact that the pin 660 is
maintained in the recessed groove 643.
Modification of Third Embodiment
[0104] As illustrated in FIG. 11, the present modification is
different from the third embodiment in terms of the configuration
of a helical groove 680 of a groove 670 of the driven-side
rotational body. Specifically, in the modification, a recessed
groove 681, which extends in the extending direction of the helical
groove 680, is formed also in the helical groove 680. The recessed
groove 681 of the helical groove 680 is connected to the recessed
groove 643 of the annular groove 640.
[0105] If the actuator 150 is operated to insert the pin 660 of the
locking member 650 into the helical groove 630 of the groove 620
when the driven-side rotational body 610 is in a state coupled to
the drive-side rotational body 110, the pin 660 becomes engaged
with the side wall 631 of the helical groove 630. Also, the
projection 661 of the pin 660 proceeds into the recessed groove 681
of the helical groove 680 and becomes engaged with the recessed
groove 681. Then, when the driven-side rotational body is rotated
and the pin 660 is moved relatively in the helical groove 630,
engagement between the projection 661 and the recessed groove 681
is maintained. In this state, where such engagement is maintained,
the pin 660 reaches the annular groove 640. Therefore, after the
pin reaches the annular groove 640, the projection 661 proceeds
into the recessed groove 643 of the annular groove 640 through the
connecting portion between the recessed groove 681 of the helical
groove 680 and the recessed groove 643 of the annular groove 640.
That is, the recessed groove 681 of the helical groove 680 guides
the projection 661 of the pin 660 into the recessed groove 643 of
the annular groove 640.
[0106] Also in this embodiment, the recessed groove 643 extends in
the extending direction of the annular groove 640 and is formed
over the entire length of the annular groove 640. As a result, even
if the driven-side rotational body 610 is rotated by inertial force
and the pin 660 is moved to the connecting portion 641 of the
annular groove 640 such that the pin 660 and the side surface of
the groove 620 become separate from each other, the projection 661
of the pin 660 is engaged with the recessed groove 643. The pin 660
is thus maintained in the annular groove 640.
[0107] The remainder of the configuration, the operation, and the
advantages of the present modification are the same as those of the
third embodiment.
Fourth Embodiment
[0108] A clutch according to a fourth embodiment will now be
described with reference to FIG. 12.
[0109] As illustrated in FIG. 12, a clutch 700 of the fourth
embodiment is different from the illustrated embodiments in terms
of the configuration of a driven-side rotational body 710 and the
configuration of a locking member 750. The remainder of the
configuration is the same as those of the first embodiment. Thus,
like or the same reference numerals are given to those components
that are like or the same as the corresponding components of the
first embodiment and detailed explanations are omitted. Position
change of each ball 130 in the corresponding ball accommodating
groove 127 caused by axial shifting of the driven-side rotational
body 710 and switching between the engaged state and the disengaged
state caused by such position change happen in the same manners as
the first embodiment. Accordingly, illustration of the balls 130
and the ball accommodating grooves 127 are omitted in FIG. 12.
[0110] As illustrated in FIG. 12, a groove 720 of a small diameter
portion 711 of the driven-side rotational body 710 includes a
helical groove 730 inclined with respect to the axial direction and
an annular groove 740, which is formed continuously from the
helical groove 730 and extends over the entire circumference of an
outer circumferential surface of the driven-side rotational body
710 and perpendicularly to the axial direction. The annular groove
740 of the groove 720 has a depth equal to the depth of the helical
groove 730. In FIG. 12, the boundary between a connecting portion
of the annular groove 740, which is connected directly to the
helical groove 730, and the helical groove 730 is represented by
the long dashed double-short dashed line.
[0111] A flange 770 projects from the outer circumferential surface
of the driven-side rotational body 710 and extends over the entire
circumference of the outer circumferential surface of the
driven-side rotational body 710. Specifically, the flange 770 is
arranged on an outer circumferential surface of the small diameter
portion 711 of the driven-side rotational body 710. That is, the
flange 770 is formed at a right side as viewed in FIG. 12A with
respect to a groove 720 in the outer circumferential surface of the
driven-side rotational body. The flange 770 extends perpendicular
to the axial direction of the driven-side rotational body 710 and
parallel to the annular groove 740.
[0112] The locking member 750 includes a pin 760, which is inserted
into the groove 720 of the driven-side rotational body 710, and a
one-way locking portion 780, which selectively proceeds and
retreats with respect to the driven-side rotational body 710 as the
pin 760 is inserted into or retracted from the groove 720. In the
fourth embodiment, the one-way locking portion 780 and the flange
770 of the driven-side rotational body 710 configure a restricting
portion.
[0113] The one-way locking portion 780 includes an engagement
member 781 and an elastic member 785, which urges the engagement
member 781 toward the driven-side rotational body 710. The elastic
member 785 is configured by, for example, a coil spring. The
one-way locking portion 780 is located at the same side with
respect to the pin 760 as the side at which the flange 770 is
arranged with respect to the groove 720 (the right side as viewed
in FIG. 12A).
[0114] The right surface of the flange 770 as viewed in FIG. 12A is
referred to as a first surface 771 and the left surface of the
flange 770 as viewed in the drawing is referred to as a second
surface 772. The right surface of the engagement member 781 as
viewed in FIG. 12A is referred to as a first surface 782 and the
left surface of the engagement member 781 as viewed in the drawing
is referred to as a second surface 783. The right surface of the
pin 760 as viewed in FIG. 12A is referred to as a first surface
761. In this case, the distances between the respective surfaces
and the shapes of the surfaces 782, 783 of the engagement member
781 are defined as follows.
[0115] As illustrated in FIG. 12A, in the locking member 750, the
distance d1 from the first surface 761 of the pin 760 to the second
surface 783 of the engagement member 781 is substantially equal to
but slightly greater than the distance d2 from a side wall 732 at a
starting end 731 of the helical groove 730 to the first surface 771
of the flange 770. The distance d3 from the first surface 761 of
the pin 760 of the locking member 750 to the first surface 782 of
the engagement member 781 is substantially equal to but slightly
smaller than the distance d4 from a side wall 741 of the annular
groove 740 (the position represented by the long dashed
double-short dashed line in the connecting portion of the annular
groove 740) to the second surface 772 of the flange 770. In the
engagement member 781, the distal end of the first surface 782 is a
corner and the distal end of the second surface 783 is a chamfered
round surface. That is, the second surface 783 is inclined such
that the first surface 782 approaches the first surface 782 in a
distal direction. In other words, the distal end of the engagement
member 781 is inclined and becomes gradually smaller in size.
[0116] Accordingly, when the driven-side rotational body 710 is in
a coupled state and the pin 760 is inserted in the starting end 731
of the helical groove 730 of the groove 720 as illustrated in FIG.
12B, the second surface 783 of the engagement member 781 is in
contact with the first surface 771 of the flange 770. The second
surface 783 of the engagement member 781, which contacts the flange
770 at this stage, has the inclined distal end as has been
described. Also, referring to FIG. 12D, when the pin 760 is
inserted in the annular groove 740 of the groove 720, the
engagement member 781 is in contact with the second surface 772 of
the flange 770. The distal end of the first surface 782 of the
engagement member 781, which contacts the flange 770 at this stage,
is the corner as has been described.
[0117] Operation of the present embodiment will now be
described.
[0118] Referring to FIG. 12A, the driven-side rotational body 710
is located at a coupled position and the driven-side rotational
body 710 is in a state coupled to the drive-side rotational body
110. In this state, by operating the actuator 150 to insert the pin
760 of the locking member 750 into the helical groove 730 of the
groove 720, the state illustrated in. FIG. 12B is brought about. In
this manner, the pin 760 is engaged with a side wall 732 of the
helical groove 730, thus locking the driven-side rotational body
120 against the urging force of the urging members 135. Then, as
the driven-side rotational body 710 is rotated, the pin 760 is
moved relatively in the groove 720 in a circumferential direction
while being engaged with the side wall 732 of the helical groove
730. The driven-side rotational body 710 is thus shifted from the
coupled position to a decoupled position.
[0119] As the driven-side rotational body 710 is shifted to the
decoupled position, the position of the pin 760 in the groove 720
is shifted relatively in a direction from the helical groove 730
toward the annular groove 740. Correspondingly, the engagement
member 781, which is fixed to the locking member 750 together with
the pin 760, is shifted relative to the driven-side rotational body
710. As illustrated in FIG. 123, when the pin 760 is inserted in
the starting end 731 of the helical groove 730 of the groove 720,
the engagement member 781 faces the first surface 771 of the flange
770. The second surface 783 of the engagement member 781, which
faces the flange 770, has the inclined distal end. That is, the
surface by which the engagement member 781 contacts the flange 770
when the driven-side rotational body 710 is shifted from the
coupled position to the decoupled position is inclined. Therefore,
when the driven-side rotational body 710 is moved from the coupled
position to the decoupled position, the flange 770 and the
engagement member 781 contact each other, as illustrated in FIG.
12C, to cause the force for pressing the engagement member 781 back
against the urging force of the elastic member 785 such that the
engagement member 781 moves past the flange 770. In this manner,
when the pin 760 is inserted in the helical groove 730 of the
groove 720, movement of the driven-side rotational body 710 from
the coupled position to the decoupled position is permitted despite
the fact that the engagement member 781 is in contact with the
flange 770.
[0120] Then, as illustrated in FIG. 12D, when the driven-side
rotational body 710 is rotated by inertial force at the decoupled
position and the pin 760 is moved relatively in the annular groove
740, the engagement member 781 faces the first surface 771 of the
flange 770. As has been described, the first surface 782 of the
engagement member 781 contacts the flange 770 in this state and the
distal end of the first surface 782 is the corner. Therefore, when
the pin 760 is moved relatively in the annular groove 740 of the
groove 720, the engagement member 781 is prevented from being
pressed back by the flange 770 against the urging force of the
elastic member 785, and engagement between the engagement member
781 and the flange 770 is thus maintained. In this manner, movement
of the driven-side rotational body 710 from the decoupled position
to the coupled position is restricted. That is, even when the
driven-side rotational body 710 is arranged at the decoupled
position and rotated by inertial force and, in this state, the pin
760 is moved to the connecting portion of the annular groove 740 to
separate the pin 760 from the side surface of the groove 720 (the
side wall 741 of the annular groove 740), the one-way locking
portion 780 restricts shifting of the driven-side rotational body
710. The pin 760 is thus held in the annular groove 740.
[0121] To switch the clutch 700 from the disengaged state to the
engaged state, the actuator 150 is operated to retract the pin 760
of the locking member 750 from the annular groove 740 of the groove
720. This also causes disengagement between the engagement member
781 and the flange 770. The driven-side rotational body 710 is thus
moved to the coupled position by the urging force of the urging
members 135. As a result, the driven-side rotational body 710 and
the drive-side rotational body 110 become coupled to each other,
thus switching the clutch 700 to the engaged state.
[0122] The fourth embodiment achieves the following advantage (6)
as well as an advantage equivalent to the advantage (1) of the
first embodiment.
[0123] (6) Unless the pin 760 is shifted to be retracted from the
annular groove 740 to disengage the flange 770 and the one-way
locking portion 780 from each other, the pin 760 is not shifted
from the annular groove 740 to the helical groove 730. That is, the
flange 770 and the one-way locking portion 780 function as a
restricting portion. This restricts shifting of the pin 760 from
the annular groove 740 to the helical groove 730 when the pin 760
is inserted in the annular groove 740. As a result, it is possible
to restrain shifting of the driven-side rotational body 710 to the
coupled position despite the fact that the pin 760 is maintained in
the groove 720.
Fifth Embodiment
[0124] A clutch according to a fifth embodiment will now be
described.
[0125] As illustrated in FIG. 13, a clutch 800 of the fifth
embodiment is different from the fourth embodiment in terms of the
configuration of the locking member 750. The remainder of the
configuration is the same as those of the first embodiment. Thus,
like or the same reference numerals are given to those components
that are like or the same as the corresponding components of the
first embodiment and detailed explanations are omitted. The fifth
embodiment is the same as the first embodiment in terms of position
change of each ball 130 in the corresponding ball accommodating
groove 127 caused by axial shifting of the driven-side rotational
body 710 and switching between the engaged state and the disengaged
state caused by such position change. Accordingly, illustration of
the balls 130 and the ball accommodating grooves 127 is omitted
also in FIG. 13.
[0126] With reference to FIG. 13, the driven-side rotational body
710 of the fifth embodiment is configured identically with the
driven-side rotational body 710 of the fourth embodiment. The
flange 770 is formed in the driven-side rotational body 710.
[0127] A locking member 850 includes a pin 860, which is inserted
into the groove 720 of the driven-side rotational body 710, and a
one-way locking portion 880, which selectively proceeds and
retreats with respect to the driven-side rotational body 710 as the
pin 860 is inserted into or retracted from the groove 720. In the
fifth embodiment, the one-way locking portion 880 and the flange
770 of the driven-side rotational body 710 configure a restricting
portion.
[0128] The one-way locking portion 880 includes an engagement
member 881, a pivot shaft 885 through which the engagement member
881 is pivotally supported by the locking member 850, and a
restricting member 888, which restricts pivot of the engagement
member 881 in a certain direction (a leftward direction in FIG.
13A). As illustrated in FIG. 13A, a state in which the distal end
of the engagement member 881 projects toward the driven-side
rotational body 710 is defined as a reference position of the
engagement member 881. The restricting member 888 restricts tilting
of the engagement member 881 in a specific direction from the
reference position and permits tilting of the engagement member 881
in another direction (a rightward direction in FIG. 13A) from the
reference position.
[0129] The right surface of the flange 770 as viewed in FIG. 13A is
referred to as the first surface 771 and the left surface of the
flange 770 as viewed in the drawing is referred to as the second
surface 772. The right surface of the engagement member 881 as
viewed in FIG. 13A and the left surface of the engagement member
881 as viewed in the drawing when the engagement member 881 is
arranged at the reference position are referred to as a first
surface 882 and a second surface 883, respectively. The right
surface of the pin 860 as viewed in FIG. 13A is referred to as a
first surface 861.
[0130] In this case, the distances between the respective surfaces
are defined as follows.
[0131] As illustrated in FIG. 13A, in the locking member 850, the
distance d1 from the first surface 861 of the pin 860 to the second
surface 883 of the engagement member 881 is substantially equal to
but slightly greater than the distance d2 from the side wall 732 of
the helical groove 730 at the starting end 731 to the first surface
771 of the flange 770. The distance d3 from the first surface 861
of the pin 860 of the locking member 850 to the first surface 882
of the engagement member 881 is substantially equal to but slightly
smaller than the length d4 from the side wall 741 of the annular
groove 740 (the position represented by the long dashed
double-short dashed line corresponding to the boundary position
between the annular groove 740 and the helical groove 730 in the
connecting portion of the annular groove 740) to the second surface
772 of the flange 770.
[0132] Accordingly, when the driven-side rotational body 710 is in
a coupled state and the pin 860 is inserted in the starting end 731
of the helical groove 730 of the groove 720 as illustrated in FIG.
13B, the second surface 883 of the engagement member 881 is in
contact with the first surface 771 of the flange 770. Also, as
illustrated in FIG. 13D, when the pin 860 is arranged in the
annular groove 740 of the groove 720, the engagement member 881 is
in contact with the second surface 772 of the flange 770.
[0133] Operation of the present embodiment will now be
described.
[0134] Referring to FIG. 13A, the driven-side rotational body 710
is located at a coupled position and the driven-side rotational
body 710 is in a state coupled to the drive-side rotational body
110. In this state, by operating the actuator 150 to insert the pin
860 of the locking member 850 into the starting end 731 of the
helical groove 730 of the groove 720, the state illustrated in FIG.
13B is brought about. In this manner, the pin 860 is engaged with
the side wall 732 of the helical groove 730, thus locking the
driven-side rotational body 120 against the urging force of the
urging members 135. Then, as the driven-side rotational body 710 is
rotated, the pin 860 is moved relatively in the groove 720 in a
circumferential direction while being engaged with the side wall
732 of the helical groove 730. The driven-side rotational body 710
is thus shifted from the coupled position to a decoupled
position.
[0135] As the driven-side rotational body 710 is shifted to the
decoupled position, the position of the pin 860 in the groove 720
is shifted relatively in a direction from the helical groove 730
toward the annular groove 740. Correspondingly, the engagement
member 881, which is fixed to the locking member 850 together with
the pin 860, is shifted relative to the driven-side rotational body
710. As illustrated in FIG. 13B, when the pin 860 is inserted in
the starting end 731 of the helical groove 730, the engagement
member 881 is in contact with the first surface 771 of the flange
770. The engagement member 881 is permitted to tilt in the certain
direction (the rightward direction as viewed in FIGS. 13) from the
reference position, at which the engagement member 881 contacts the
flange 770. Therefore, when the driven-side rotational body 710 is
moved from the coupled position to the decoupled position, the
engagement member 881 contacts the flange 770 and tilts, thus moves
past the flange 770, as illustrated in FIG. 13C. In this manner,
when the pin 860 is inserted in the starting end 731 of the helical
groove 730, movement of the driven-side rotational body 710 from
the coupled position to the decoupled position is permitted despite
the fact that the engagement member 881 is in contact with the
flange 770.
[0136] Then, as illustrated in FIG. 13D, when the driven-side
rotational body 710 is rotated by inertial force at the decoupled
position and the pin 860 is moved relatively in the annular groove
740, the engagement member 881 faces the second surface 772 of the
flange 770 and the first surface 882 of the engagement member 881
contacts and becomes engaged with the second surface 772 of the
flange 770. When the pin 860 is moved relatively in the annular
groove 740 of the groove 720, tilting of the engagement member 881
in the certain direction (the leftward direction as viewed in FIG.
13D) is restricted by the restricting member 888. The engagement
member 881 is thus prevented from tilting even if the urging force
of the urging members 135 acts on the driven-side rotational body
710 such that the engagement member 881 is pressed by the flange
770. As a result, the engagement member 881 is held at the
reference position, thus maintaining engagement between the
engagement member 881 and the flange 770. This restricts movement
of the driven-side rotational body 710 from the decoupled position
to the coupled position. That is, even when the driven-side
rotational body 710 is arranged at the decoupled position and
rotated by inertial force and, in this state, the pin 860 is moved
to the connecting portion of the annular groove 740 such that the
pin 860 becomes separate from the side surface of the groove 720
(the side wall 741 of the annular groove 740), the one-way locking
portion 880 restricts shifting of the driven-side rotational body
710. The pin 860 is thus held in the annular groove 740.
[0137] To switch the clutch 800 from the disengaged state to the
engaged state, the actuator 150 is operated to retract the pin 860
of the locking member 850 from the annular groove 740 of the groove
720. This also causes disengagement between the engagement member
881 and the flange 770. The driven-side rotational body 710 is thus
moved to the coupled position by the urging force of the urging
members 135. As a result, the driven-side rotational body 710 and
the drive-side rotational body 110 become coupled to each other,
thus switching the clutch 800 to the engaged state.
[0138] The fifth embodiment achieves advantages equivalent to the
advantage (1) of the first embodiment and the advantage (6) of the
fourth embodiment.
[0139] The clutch according to the present disclosure is not
restricted to the configurations illustrated in the above-described
embodiments but may be embodied in, for example, the forms
described below, which are modifications of the embodiments.
[0140] In the first embodiment, the depth of the annular groove 420
is small in the vicinity of the starting end 421 relative to the
depths of the other portions in the circumferential direction of
the driven-side rotational body 120. The depth of the helical
groove 410 becomes gradually greater from the starting end 411 to
the finishing end 412. However, the depth of the annular groove or
the depth of the helical groove may be uniform in the
circumferential direction. That is, the step between the annular
groove and the helical groove may be set to a uniform size in the
circumferential direction of the driven-side rotational body
120.
[0141] In the second embodiment, the protrusion is formed over the
entire length of the connecting portion of the groove. The opposite
ends of the protrusion reach the non-connecting portion. However,
if the protrusion is formed at least over the entire length of the
connecting portion of the groove, shifting of the pin into the
helical groove can be restrained by engaging the protrusion with
the recess of the pin over the entire length of the connecting
portion. The opposite ends of the protrusion thus do not
necessarily have to reach the non-connecting portion. For example,
only one of the end portions may reach the non-connecting portion.
Alternatively, the length of the protrusion may be equal to the
length of the connecting portion such that neither end portion
reaches the non-connecting portion. Further, as long as shifting of
the pin from the annular groove into the helical groove is
restrained and disengagement of the clutch is restrained, the
protrusion does not necessarily have to extend over the entire
length of the connecting portion. For example, the protrusion may
be provided in a portion of the connecting portion of the
groove.
[0142] In the third embodiment and its modification, the recessed
groove is formed over the entire length of the annular groove.
However, the recessed groove only has to be formed at least over
the entire length of the connecting portion of the annular groove.
That is, if the protrusion is formed at least over the entire
length of the connecting portion, shifting from the annular groove
into the helical groove is restrained. Further, if shifting of the
pin from the annular groove into the helical groove is restrained
and disengagement of the clutch is restrained, the recessed groove
may be formed in a portion of the connecting portion.
[0143] In the fourth and fifth embodiments, the flange is formed
over the entire circumference of the outer circumferential surface
of the driven-side rotational body. However, if shifting of the pin
from the annular groove into the helical groove is restrained and
disengagement of the clutch is restrained, the flange does not
necessarily have to extend over the entire circumference but may be
arranged in a portion of the outer circumferential surface to
extend in the circumferential direction of the driven-side
rotational body.
[0144] The number of the urging members may be modified as needed.
For example, a single urging member may be employed to urge the
driven-side rotational body.
[0145] Any suitable urging member may be employed as long as the
urging member urges the driven-side rotational body toward the
coupled position. The urging member is thus not restricted to the
aforementioned compression coil spring. For example, a tension
spring for pulling the driven-side rotational body toward the
coupled position may be employed as the urging member.
[0146] The actuator is not restricted to the self-holding type
solenoid but may be, for example, a solenoid having a locking
member that is inserted into a groove only when a coil is
energized. In this configuration, the clutch is disengaged only
when the coil is energized. The clutch is thus maintained in the
engaged state if the coil cannot be energized. As a result, even
when the actuator fails to operate normally, the pump can be
operated.
[0147] The actuator is not restricted to a solenoid. That is, any
other suitable actuator than the solenoid, such as a hydraulic type
actuator, may be used to selectively insert and retract the locking
member. Also in this case, the clutch is disengaged through
engagement between a groove of the driven-side rotational body and
the locking member. The force needed to disengage the clutch is
thus obtained from rotational force of the driven-side rotational
body. As a result, disengagement is carried out by small force.
[0148] The clutch is not restricted to the configuration in which
drive force is transmitted through the balls. The clutch may be a
pressing type clutch.
[0149] For example, opposed surfaces of the driven-side rotational
body and the drive-side rotational body may be parallel tapered
surfaces each inclined with respect to the axial direction. The
tapered surfaces serve as pressing surfaces. By moving the
driven-side rotational body in the axial direction and pressing the
pressing surfaces against each other, the driven-side rotational
body and the drive-side rotational body are coupled to each
other.
[0150] In the clutch of each of the illustrated embodiments, the
shapes of the components are not restricted particularly to the
shapes of the illustrated embodiments, as long as the operation
illustrated for each embodiment is ensured. For example, as
illustrated in FIG. 14, ball accommodating grooves 927 may be
formed in a large diameter portion 922 of a driven-side rotational
body 910 and recesses 928 may be formed by lightening portions that
lack the ball accommodating grooves 927. This decreases the weight
of the driven-side rotational body 910 and thus reduces the
inertial force caused by the driven-side rotational body 910. As a
result, when the driven-side rotational body 910 reaches a
decoupled position, rotation of the driven-side rotational body 910
quickly stops.
[0151] In each of the illustrated embodiments, the clutch switches
the state of power transmission from the crankshaft to the pump.
However, the clutch according to the present disclosure may be
employed as a clutch arranged between other auxiliary devices, such
as a compressor or an oil pump, and the crankshaft. Also, the
clutch according to the present disclosure is not restricted to the
clutch for switching the state of power transmission from the
crankshaft but may be used as a clutch for switching the state of
power transmission from other drive sources.
* * * * *