U.S. patent application number 11/945305 was filed with the patent office on 2008-06-19 for starting clutch.
Invention is credited to Yosuke Ikeda, Shun Kitahara, Tomoyuki Miyazaki, Masaki Sakai, Manabu Sawayanagi.
Application Number | 20080142331 11/945305 |
Document ID | / |
Family ID | 39525810 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080142331 |
Kind Code |
A1 |
Miyazaki; Tomoyuki ; et
al. |
June 19, 2008 |
STARTING CLUTCH
Abstract
The present invention provides a starting clutch disposed
between a transmission and an engine and having a wet type
multi-plate clutch for transmitting a power, in which the wet type
multi-plate clutch includes a plurality of friction plates housed
for an axial sliding movement, a clutch drum for housing the
friction plates, and a piston for urging a radial central region or
therearound of the friction plate to engage the friction plates,
and oil which has lubricated the wet type multi-plate clutch is
temporarily trapped within the clutch drum and then is
discharged.
Inventors: |
Miyazaki; Tomoyuki;
(Fukuroi-shi, JP) ; Kitahara; Shun; (Fukuroi-shi,
JP) ; Sawayanagi; Manabu; (Fukuroi-shi, JP) ;
Sakai; Masaki; (Fukuroi-shi, JP) ; Ikeda; Yosuke;
(Fukuroi-shi, JP) |
Correspondence
Address: |
MILES & STOCKBRIDGE PC
1751 PINNACLE DRIVE, SUITE 500
MCLEAN
VA
22102-3833
US
|
Family ID: |
39525810 |
Appl. No.: |
11/945305 |
Filed: |
November 27, 2007 |
Current U.S.
Class: |
192/70.12 |
Current CPC
Class: |
F16D 13/54 20130101;
F16D 25/123 20130101; F16D 2069/004 20130101; F16D 25/0638
20130101 |
Class at
Publication: |
192/70.12 |
International
Class: |
F16D 13/52 20060101
F16D013/52 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2006 |
JP |
2006-338303 |
Claims
1. A starting clutch disposed between an engine and a transmission
and having a wet type multi-plate clutch for transmitting a power,
wherein: said wet type multi-plate clutch comprises a plurality of
friction plates housed for an axial sliding movement, and radial
central regions of said friction plate are urged from both sides in
an axial direction.
2. A starting clutch according to claim 1, wherein said wet type
multi-plate clutch includes a piston for urging the radial central
region of said friction plate to engage said friction plates, and
said piston has an axially extending protruded portion for urging
the radial central region of said friction plate.
3. A starting clutch according to claim 2, wherein an abutting
member for abutting against said friction plate is provided at an
opposite side from said piston, and said abutting member has an
axially extending projection for urging the radial central region
of said friction plate.
4. A starting clutch according to claim 3, wherein said protruded
portion of said piston and said projection of said abutting member
are arranged on the same single line.
5. A starting clutch according to claim 1, wherein said wet type
multi-plate clutch comprises a plurality of friction plates housed
for an axial sliding movement, and a clutch drum for housing said
friction plates, and further wherein oil which has lubricated said
wet type multi-plate clutch is trapped within said clutch drum and
then is discharged.
6. A starting clutch according to claim 1, wherein said wet type
multi-plate clutch includes a piston for urging the radial central
region of said friction plate to engage said friction plates, and
said piston has an urging portion for abutting against said
friction plate to apply an urging force to said friction plate, and
a base portion connected to said urging portion, and said urging
portion has is provided at its tip end with a curved portion
protruding toward an abutting direction with respect to said
friction plate.
7. A starting clutch according to claim 6, wherein a member having
a curved portion for abutting against said friction plate is
provided at a position opposed to said piston with the
interposition of said friction plates.
8. A starting clutch according to claim 6, wherein said wet type
multi-plate clutch comprises a plurality of friction plates housed
for an axial sliding movement, and a clutch drum for housing said
friction plates, and further wherein oil which has lubricated said
wet type multi-plate clutch is trapped within said clutch drum and
then is discharged.
9. A starting clutch according to claim 5, wherein said clutch drum
is not provided at its outer periphery with an oil discharging port
extending in a radial direction.
10. A starting clutch according to claim 5, wherein said clutch
drum is provided at its inner periphery with spline grooves with
which splines of said friction plates are engaged, and further
wherein the oil is discharged through said spline grooves in the
axial direction.
11. A starting clutch according to claim 5, further comprising a
cover member for covering an open portion of said clutch drum.
12. A starting clutch according to claim 11, wherein said cover
member is rotated together with said clutch drum to drive an oil
pump.
13. A starting clutch according to claim 5, wherein said clutch
drum is covered by a clutch cover, and said starting clutch is
housed in a housing, and said clutch cover is formed integrally
with said housing.
14. A starting clutch according to claim 5, wherein said clutch
drum is covered by a clutch cover, and said starting clutch is
housed in a housing, and said clutch cover is formed separately
from said housing.
15. A starting clutch according to claim 5, wherein a driving force
from an engine is transmitted to said clutch drum through a
housing.
16. A starting clutch according to claim 5, wherein a driving force
from an engine is transmitted from a housing member to said clutch
drum through a damper device.
17. A starting clutch according to claim 15, wherein a gap between
the open end of said clutch drum and said housing member is
narrower than other parts.
18. A starting clutch according to claim 15, wherein said clutch
drum is provided at its inner periphery with spline grooves with
which splines of said friction plates are engaged, and further
wherein the oil is discharged through said spline grooves in the
axial direction.
19. A starting clutch according to claim 15, wherein a cover member
is provided to cover said wet type multi-plate clutch at an open
portion of said clutch drum.
20. A starting clutch according to claim 19, wherein, in an inner
surface of said cover member or said housing, a protruded portion
or a fin is provided on an inner diameter surface of said cover
member to direct the oil discharged from the axial direction toward
an inner diameter direction.
21. A starting clutch according to claim 19, wherein, the
lubricating oil passage for supplying the lubricating oil is
separated from the lubricating oil passage for discharging the
lubricating oil.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a starting clutch which can
be used in place of a torque converter for a motor vehicle and the
like.
[0003] 2. Description of the Related Art
[0004] In the past, in automatic transmissions, the starting of a
vehicle has been achieved through torque transmission of a torque
converter. The torque converter has been mounted on many vehicles
since the torque converter serves to amplify the torque and also
provides smooth torque transmission.
[0005] On the other hand, the torque converter has disadvantages
that a slip amount is increased during the torque transmission and
that efficiency is relatively bad.
[0006] Thus, in recent years, it has been proposed that a starting
clutch is used in place of the torque converter and it has also
been implemented that, in a low speed range, the torque is
amplified by increasing a gear ratio and by increasing the number
of transmission stages.
[0007] In general, the starting clutch includes a wet type
multi-plate clutch housed in a clutch drum. In the multi-plate
clutch, friction plates as friction engaging elements at an output
side and separator plates as friction engaging elements at an input
side are alternately arranged along an axial direction. With this
arrangement, when the friction plates and the separator plates are
engaged with each other by a piston, a power can be
transmitted.
[0008] In the starting clutch, since great heat is generated, it is
necessary to supply a large amount of lubricating oil for the
cooling. Thus, although an oil pump must has a great pump capacity,
a pump capacity of an oil pump provided in the conventional
transmission is insufficient, and, therefore, there arises a
problem that such an insufficient oil pump cannot be mounted to the
starting clutch as it is. Further, since the conventional oil pumps
perform the cooling operation with a small amount of oil, heat may
be accumulated in the clutch portion and then the clutch may be
burned.
[0009] Japanese Patent Application Laid-open No. 2002-357232
discloses a starting clutch in which a large amount of lubricating
oil is used to cool the clutch and a plurality of holes is provided
to discharge the lubricating oil along a radial direction of a
clutch drum. In this case, however, since the lubricating oil is
discharged faster from the clutch portion, heat exchange between
the clutch portion and the oil cannot be achieved sufficiently,
with the result that the cooling efficiency of the clutch may be
worsened and the heat is apt to be accumulated in the clutch
portion. Further, as described in U.S. Pat. No. 6,929,105, if the
oil is filled, although the heat of the clutch portion is
transmitted to the oil, the oil is retained in the clutch portion
for a longer term, and, thus, similar to the above-mentioned
Japanese Patent Application Laid-open No. 2002-357232, the heat may
not be removed from the clutch portion smoothly.
SUMMARY OF THE INVENTION
[0010] Accordingly, an object of the present invention is to
provide a starting clutch in which heat of the clutch can be cooled
efficiently with a small amount of lubricating oil and a sufficient
cooling operation can be achieved even when an oil pump provided in
an existing transmission is used.
[0011] To achieve the above object, the present invention provides
a starting clutch disposed between a transmission and an engine and
having a wet type multi-plate clutch for transmitting a power,
wherein the wet type multi-plate clutch comprises a plurality of
friction plates housed for an axial sliding movement, a clutch drum
for housing the friction plates therein, and a piston for urging a
substantially radial central portion of the friction plate to
engage the friction plates with each other, and further wherein
lubricating oil which has lubricated the wet type multi-plate
clutch is trapped in the clutch drum and then is discharged.
[0012] According to the starting clutch of the present invention,
the following effects can be obtained.
[0013] Since the piston for urging the substantially radial central
portion of the friction plate to engage the friction plates with
each other is provided, face pressure distribution on a friction
surface of each friction plate becomes uniform, thereby providing a
starting clutch having a good heat resisting ability and a stable
operation.
[0014] Since the cooling oil supplied to the friction plates
efficiently is temporarily trapped in an inner diameter side of a
hub member and in the clutch thereby to absorb the heat from the
clutch portion and then is quickly discharged from the clutch
portion toward the transmission by a centrifugal action of the
clutch portion, both reduction in the capacity of the oil pump and
the heat resisting ability of the starting clutch can be
compatible, thereby enhancing reduction in fuel consumption and
enhancing reliability.
[0015] Further, the starting clutch can be cooled with a small
amount of oil and the starting clutch can be attached to the
existing transmission.
[0016] Further features of the present invention will become
apparent from the following description of an exemplary embodiment
(with reference to the attached drawing).
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an axial sectional view showing a starting clutch
according to a first embodiment of the present invention;
[0018] FIG. 2 is an axial sectional view showing a starting clutch
according to a second embodiment of the present invention;
[0019] FIG. 3 is an axial sectional view showing a starting clutch
according to a third embodiment of the present invention;
[0020] FIG. 4 is a partial front view of a friction plate used in
the embodiments of the present invention; and
[0021] FIG. 5 is an enlarged sectional view showing a clutch
portion of FIG. 1 in detail.
DESCRIPTION OF THE EMBODIMENTS
[0022] Now, embodiments of the present invention will be fully
described with reference to the accompanying drawings.
Incidentally, it should be noted that the illustrated embodiments
are merely exemplary and various changes can be made within the
scope of the present invention.
First Embodiment
[0023] FIG. 1 is an axial sectional view showing a starting clutch
according to a first embodiment of the present invention. The
starting clutch 10 includes a clutch drum 1 and a wet type
multi-plate clutch 30 housed within the clutch drum. The wet type
multi-plate clutch 30 comprises substantially annular friction
plates (internally-toothed plates) 3 as friction engaging elements
at an output side and substantially annular separator plates
(externally-toothed plates) 4 as friction engaging elements at an
input side, which plates are arranged alternately along an axial
direction within the clutch drum 1. Within one axial end (open end)
of the clutch drum 1, a substantially annular backing plate 6 is
fixedly supported by a substantially annular stop ring 5 in the
axial direction, thereby holding the separator plates 4.
[0024] The annular clutch drum 1 is provided at its inner periphery
with a central cylindrical portion 32 and is also provided at its
outer periphery with an outer diameter portion i.e. drum portion 34
opposed to the cylindrical portion 32 in a radial direction. The
drum portion 34 is provided at its inner periphery with a spline
portion 39 with which the separator plates 4 are engaged for an
axial sliding movement. At an axial opposite end of the cylindrical
portion 32, there is provided a protruded portion 33 which is
fitted into a recessed portion 38 of a crankshaft 11. Further, the
cylindrical portion 32 is supported by an input shaft 16 connected
to a transmission (not shown) through a hub member 2 and a bearing
51, which will be described later.
[0025] In the illustrated embodiment, although the wet type
multi-plate clutch 30 is constituted by three friction plates 3 and
four separator plates 4, it should be noted that the number of such
friction engaging elements at the input and output sides can be
changed voluntarily in accordance with the required torque.
Further, a substantially annular friction material 35 or a
plurality of friction material segments is fixed to on both axial
surfaces of the friction plate 3 by an adhesive. Further, a
friction material 35 may be fixed to the separator plate
(externally-toothed plate) 4 or friction materials 35 may be fixed
to one surface of the friction plate (internally-toothed plate) 3
and one surface of the separator plate 4 alternately.
[0026] In FIG. 1, at the open end portion of the clutch drum 1
within the clutch drum 1, a piston 8 is fitted on the outer
periphery of the cylindrical portion 32 for an axial sliding
movement, and a hydraulic chamber 31 for applying oil pressure to
the piston 8 is defined between the piston 8 and the clutch drum 1.
At opposite side of the piston 8 from the hydraulic chamber 31, a
plate 70 is secured to the cylindrical portion 32. An axial one end
of a spring 9 is secured to the plate 70. The other axial end of
the spring 9 abuts against the piston 8 to apply a predetermined
urging force to the piston 8, thereby always biasing the piston 8
toward the hydraulic chamber 31 i.e. toward a disengaging or
releasing direction of the clutch. Here, although the spring 9 is
shown as a coil spring having predetermined elasticity, other type
of spring may be used. Projections 55 protruding toward the axial
direction are provided on a surface of the piston 8 opposed to the
separator plate 4 and on plate surfaces far from the piston 8, so
that, when the projection 55 urge the centers or therearound of
load acting points of the separator plates 4, friction surfaces of
all of the plates are contacted with each other with uniform face
pressure throughout the entire engaging areas, whereby the wet type
multi-plate clutch 30 is engaged or tightened. Further, due to the
uniform face pressure, offset of the heated regions can be
prevented, thereby enhancing the heat resisting ability of the
clutch portion.
[0027] The hub member 2 fitted on the input shaft 16 of the
transmission to be rotated integrally with the input shaft 16 is
provided at its outer periphery with a spline portion 36. The
friction plates 3 are fitted in the spline portion 36 having axial
through-holes 37 for an axial sliding movement. Accordingly, a
power inputted from the crankshaft 11 of the engine (not shown) is
transmitted to the transmission (not shown) through a drive plate
100 through a damper device 14 (described later), clutch drum 1,
wet type multi-plate clutch 30, hub member 2 and input shaft
16.
[0028] The clutch drum 1 of the wet type multi-plate clutch 30 is
covered by a cover portion 13 which is a part of a housing 12.
Further, a damper device 14 as a shock absorbing mechanism for
absorbing shock generated during the clutch engagement is provided
within the housing 12. The damper device 14 is constituted by a
retainer plate 40 for holding a spring 19, and a pawl member 41
attached to an outer periphery of a cylindrical portion 53 of the
clutch drum 1 and fitted on the spring 19. The retainer plate 40 is
secured to the drive plate 100 by nuts 42. Further, thrust needle
bearings 43 are disposed between the clutch drum 1 and the housing
12.
[0029] The input shaft 16 of the transmission to which the power
from the engine is transmitted is provided with an oil supplying
path 52 extending in the axial direction. Hydraulic oil supplied
from a supply source (not shown) is supplied to the hydraulic
chamber 31 which is maintained to an oil-tight condition by a
plurality of seal members, through a gap between the input shaft 16
and the cylindrical portion 53 and then through a radial through
hole 60 formed in the cylindrical portion 32 of the clutch drum
1.
[0030] At an axial one end, the input shaft 16 is provided at its
outer periphery with a spline portion into which a cylindrical
portion 50 of the hub member 2 is spline-fitted. That is to say,
the input shaft 16 can be rotated integrally with the hub member 2.
A thrust washer 61 is disposed between the hub member 2 and the
cylindrical portion 53 of the clutch drum 1 and the end of the
input shaft 16. The thrust washer 61 may be a needle bearing.
[0031] As mentioned above, the hub member 2 is fitted on the input
shaft of the transmission for the axial sliding movement and the
cylindrical portion 32 of the clutch drum 1 is fitted into the
cylindrical portion 50 of the hub member 2 through a bearing 51 for
a relative rotational movement. A protruded portion 33 of the
clutch drum 1 extending toward the engine is supported by the
crankshaft 11 and the cylindrical portion 32 of the clutch drum 1
extending toward the transmission is supported by an outer
peripheral surface of the cylindrical portion 50 of the hub member
2.
[0032] A cover member 7 is provided at the open end portion of the
clutch drum 1. An outer diameter edge portion 63 of the cover
member 7 is fitted into the spline portion 39 of the clutch drum 1.
Thus, the cover member 7 is rotated together with the clutch drum
1. An inner diameter side of the cover member 7 constitutes a
cylindrical portion 62 so that an axial lubricating oil passage 21
is defined between the cylindrical portion and the input shaft 16.
An axial end 64 of the cylindrical portion 62 is connected to an
oil pump 15 so that the oil pump 15 is operated by a rotation of
the cover member 7. The oil from the oil pump 15 is temporarily
supplied to a hydraulic control device (not shown) of the
transmission and then is supplied to the starting clutch 10 and a
brake portion (not shown) and a clutch portion (not shown) of the
transmission as operating oil and is also supplied to various parts
of the starting clutch 10 and the transmission to lubricate these
parts.
[0033] The cover member 7 as means for trapping the oil supplied
for the lubrication in the interior of the hub member 2 is
rotatably supported by a side wall 65 of the transmission through a
needle bearing 66. As can be seen from FIG. 1, by providing the
cover member 7, the wet type multi-plate clutch 30 is situated
within a substantially enclosed space. A transmission case 18
disposed in adjacent to the starting clutch 10 is provided at its
side wall with an oil returning port 17 extending in the axial
direction.
[0034] An intermediate portion 91 extends from an end of the
cylindrical portion 50 of the hub member 2 at the transmission side
in the radial direction and then is bent toward the engine at an
intermediate region and then extends toward the transmission in the
axial direction thereby to form a spline portion 36. Further, an
intermediate portion 90 extends from an end of the cylindrical
portion 62 of the cover member 7 at the engine side in the radial
direction and then is bent toward the transmission at an
intermediate region and then further extends radially outwardly to
form an outer diameter edge portion 63. The intermediate portions
90 and 91 are adjacent to and opposed to each other to define a
narrow passage 22 therebetween.
[0035] As can be seen from FIG. 1, the hub member 2, spline portion
36 and cover member 7 define a space S enclosed at the inner
diameter side of the hub member 2. Accordingly, the oil directed
from the passage 22 toward the outer diameter side can be supplied
efficiently to the clutch portion by the presence of the space S.
Further, in the clutch portion disposed at the downstream side of
the space S, the oil is apt to be trapped by not providing
lubricating oil discharging hole(s) at the outer diameter side of
the clutch drum or by reducing the number of the discharging holes
or reducing sizes of the discharging holes.
[0036] A free end of the hub member 2 at the opposite side (inner
diameter side) from the spline portion 36 is provided with a
projection 75 protruding toward the inner diameter direction. The
projection 75 acts as means for staying or trapping the oil (to be
supplied for the lubrication) within the inner diameter side of the
hub member 2 and is provided as a continuous or intermittent
annulus. Further, a surface of the cover member 7 opposed to the
hub member is provided with an annular protruded portion 76
protruding toward the spline portion 36 of the hub member 2. The
projection 75 and the protruded portion 76 are offset from each
other in the axial direction to define so-called labyrinth for the
lubricating oil from the passage 22 (described later) so that the
lubricating oil is apt to be trapped between the hub member 2 and
the cover member 7.
[0037] An oil returning port 17 is provided to extend through a
side wall of the transmission case 18 disposed in adjacent to the
starting clutch 10. The lubricating oil which has lubricated the
wet type multi-plate clutch 30 is returned to the interior of the
transmission through the oil returning port 17.
[0038] Now, the oil path for the lubricating oil lubricating the
wet type multi-plate clutch 30 and the oil path for supplying the
oil to the hydraulic chamber 31 will be explained. By driving the
oil pump 15, the lubricating oil for lubricating the wet type
multi-plate clutch 30 flows from the transmission to the wet type
multi-plate clutch 30 through the lubricating oil passage 21, the
passage 22 defined between the hub member 2 and the cover member 7
and the through hole 37 of the hub member 2, thereby lubricating
the wet type multi-plate clutch. Since the drum portion 34 of the
clutch drum 1 has no radial through hole, the lubricating oil which
has lubricated the wet type multi-plate clutch 30 cannot be moved
outwardly in the radial direction and thus is temporarily
accumulated within the interior of the clutch portion and then is
directed toward the axial direction i.e. toward the cover member 7
through the spline portion 39 of the clutch drum. Thus, if
necessary, the cover member 7 may include axial through hole(s) for
smoothing the flow of the lubricating oil.
[0039] After passed through the cover member 7, the lubricating oil
further flows in the axial direction and is returned to the
transmission through the oil returning port 17 formed in the side
wall of the transmission case 18. The paths through which the
lubricating oil flows are shown by the arrows in FIG. 1. As can be
understood from the above explanation, the lubricating oil is
supplied from the axial direction and is discharged in the axial
direction.
[0040] Next, a hydraulic circuit for controlling the piston 8 will
be explained. The hydraulic oil is supplied from the oil supply
source (not shown) to an oil supply path 52 formed in the input
shaft 16. The oil passed through the oil supply path 52 flows from
the gap between the input shaft 16 and the end face of the
cylindrical portion 53 and passes through a radial through hole 60
formed in the cylindrical portion 32 of the clutch drum 1 and is
supplied to the hydraulic chamber 31. By oil pressure supplied from
a hydraulic circuit (not shown), the piston 8 is shifted to the
left (FIG. 1) to tighten the wet type multi-plate clutch 30.
[0041] The above-mentioned oil path for the lubricating oil and the
hydraulic circuit for controlling the piston are provided
independently from each other. Thus, the replacement between the
starting clutch of the present invention and the existing torque
converter can easily be made.
[0042] Next, a procedure for attaching the starting clutch of the
present invention between the engine and the transmission is as
follows. First of all, the starting clutch 10 and the damper device
14 are assembled as a unit which is in turn inserted into the
spline portion of the input shaft 16 of the transmission. Then, the
protruded portion 33 of the clutch drum 1 is inserted into the
crankshaft 11 of the engine. Thereafter, by fixing the damper
device 14 and the drive plate, in the starting clutch 10, the
transmission and the crankshaft 11 of the engine are aligned with
each other, and the axial attachment error is absorbed, thereby
providing high accurate assembling. Further, since the clutch drum
1 at the drive side is firmly supported by the crankshaft 11 and
the input shaft 16 of the transmission, the rotational accuracy is
enhanced, and an anti-judder property and wear resisting ability of
the rotating parts are also enhanced, thereby providing good
starting performance.
[0043] As mentioned above, since it is designed so that the hub
member 2 is spline-fitted on the input shaft 16, the clutch drum 1
is fitted to the hub member 2 and the clutch drum 1 is supported by
the crankshaft 11, alignment between the parts of the clutch
portion, transmission and engine can be made effectively. Further,
since the cylindrical portion 50 of the hub member 2 is held to be
pinched between the input shaft 16 and the cylindrical portion 32
of the clutch drum 1, the rotation of the hub member 2 is
stabilized.
Second Embodiment
[0044] FIG. 2 is an axial sectional view showing a starting clutch
according to a second embodiment of the present invention. Since a
fundamental arrangement of the second embodiment is the same as
that of the first embodiment, the detailed explanation thereof will
be omitted.
[0045] The second embodiment differs from the first embodiment
regarding a construction of a clutch cover and a lubricating oil
discharging path. A clutch cover 73 covering the clutch portion 30
is provided independently from the housing 12. Although the
connection to the clutch drum 1 is similar to that in the first
embodiment, the clutch cover 73 is secured to a side wall of the
housing 12 at the transmission side by bolts 72.
[0046] The side wall 74 is provided with a through hole 71 through
which the lubricating oil which has lubricated the clutch portion
30 is discharged toward the transmission. The lubricating oil from
the clutch portion 30 passes through the through hole 71 and flows
toward the transmission. As can be seen from FIG. 2, the through
hole 71 is substantially opposed, in the axial direction, to a
friction engaging portion of the clutch portion including the
friction plates 3 and the separator plates 4, so that the
lubricating oil which has lubricated the friction engaging portion
can be directed toward the through hole 71 efficiently.
[0047] Now, urging of the friction plates will be explained in more
detail with reference to FIG. 5. FIG. 5 is an enlarged sectional
view showing details of the clutch portion of FIG. 1. An urging
surface 97 of the piston 8 is provided with an axially protruding
projection 55 for urging a radially central region or therearound
of the friction plate. Further, the backing plate 6 which abuts
against the friction plate at the opposite side from the piston 8
along the axial direction has an axially extending protruded
portion 96 for urging a radially central region or therearound of
the friction plate. That is to say, in FIG. 5, the projection 55 of
the piston 8 can abut against the rightmost separator plate 4 and
the protruded portion 96 of the backing plate 6 abuts against the
leftmost separator plate 4.
[0048] As can be seen from FIG. 5, it is preferable that the
projection 55 of the piston 8 and the protruded portion 96 of the
backing plate 6 are arranged on the same single line. Further, a
contact area between the projection 55 and the separator plate 4
and a contact area between the protruded portion 96 and the
separator plate 4 each corresponds to a substantially radial
central region of the friction surface of the friction plate i.e.
separator plate 4.
[0049] Each of the projection 55 and the protruded portion 96 can
be formed as a continuous annulus but may be formed as ring
segments with a predetermined gap therebetween. With this
arrangement, the friction plates can be engaged with each other
positively, thereby providing a starting clutch having a good heat
resisting property and a stable operation.
Third Embodiment
[0050] FIG. 3 is an axial sectional view of a starting clutch
according to a third embodiment of the present invention. The
starting clutch 10 includes a clutch drum 1 and a wet type
multi-plate clutch 30 housed in the clutch drum. The wet type
multi-plate clutch 30 comprises substantially annular friction
plates (internally-toothed plates) 3 as friction engaging elements
at an output side and substantially annular separator plates
(externally-toothed plates) 4 as friction engaging elements at an
input side, which plates are arranged alternately along an axial
direction within the clutch drum 1. Within one axial end (open end)
of the clutch drum 1, a substantially annular backing plate 79 is
fixedly supported by a substantially annular stop ring 5 in the
axial direction, thereby holding the separator plates 4. The
backing plate 79 is provided at it tip end with a curved portion
79a protruding toward the clutch portion.
[0051] The annular clutch drum 1 is provided at its inner periphery
with a central cylindrical portion 32 and is also provided at its
outer periphery with an outer diameter portion i.e. drum portion 34
opposed to the cylindrical portion 32 in a radial direction. The
drum portion 34 has no radial through holes. The drum portion 34 is
provided at its inner periphery with a spline portion 39 with which
the separator plates 4 are engaged for an axial sliding movement.
An axial opposite end of the cylindrical portion 32 is fitted onto
an outer periphery of a cylindrical portion 57 of an inner diameter
side boss 11 of the housing 12.
[0052] In the illustrated embodiment, although the wet type
multi-plate clutch 30 is constituted by three friction plates 3 and
four separator plates 4, it should be noted that the number of such
friction engaging elements at the input and output sides can be
changed voluntarily in accordance with the required torque.
Further, a substantially annular friction material 35 or a
plurality of friction material segments is fixed to on both axial
surfaces of the friction plate 3 by an adhesive. Further, a
friction material 35 may be fixed to the separator plate
(externally-toothed plate) 4 or friction materials 35 may be fixed
to one surface of the friction plate (internally-toothed plate) 3
and one surface of the separator plate 4 alternately.
[0053] In FIG. 3, a piston 8 is provided at the closed end portion
of the clutch drum 1 within the clutch drum 1. The piston 8 has an
urging portion 61 for abutting against the separator plate 4 to
apply an urging force to the separator plate, and a base portion 60
connected to the urging portion 61. The urging portion 61 is
provided at its tip end with a curved portion 68 protruding toward
an abutting direction so as to abut against the separator plate.
The base portion 60 is fitted onto the cylindrical portion 32 of
the clutch drum 1 for an axial sliding movement.
[0054] In the illustrated embodiment, it is preferable that the
curved portions 68 and 79a are arranged on the same single line.
Further, a contact area between the curved portion 68 and the
separator plate 4 and a contact area between the curved portion 79a
and the separator plate 4 each corresponds to a substantially
radial central region of the friction surface of the friction plate
i.e. separator plate 4.
[0055] Each of the curved portions 68 and 79a can be formed as a
continuous annulus but may be formed as ring segments with a
predetermined gap therebetween. With this arrangement, the friction
plates can be engaged with each other positively, thereby providing
a starting clutch having a good heat resisting property and a
stable operation.
[0056] A hydraulic chamber 31 which is maintained in an oil-tight
condition by two O-ring seals 53 is defined between the base
portion 60 and the inner surface of the clutch drum 1. By supplying
hydraulic oil from an oil path (described later) to the hydraulic
chamber 31, a shifting movement of the piston 8 can be controlled
to obtain the predetermined urging force. A spring may be provided
to apply a predetermined urging force to the piston 8, thereby
always biasing the piston 8 toward the hydraulic chamber 31 i.e.
toward a disengaging or releasing direction of the clutch.
[0057] When the predetermined hydraulic oil is supplied to the
hydraulic chamber 31, the piston 8 is shifted to the left (FIG. 3),
thereby tightening the wet type multi-plate clutch 30 between the
piston and the backing plate 79. In this case, each of apexes
(protruding toward the clutch portion) of the curved portion 68 of
the piston 8 and the curved portion 79a of the backing plate 79
urges a central region or therearound of the respective separator
plate 4. Thus, friction surfaces of all of the plates are contacted
with each other with uniform face pressure throughout the entire
engaging areas, whereby the wet type multi-plate clutch 30 is
engaged or tightened. Further, due to the uniform face pressure,
concentration of the heated regions can be prevented, thereby
enhancing the heat resisting ability of the clutch portion.
[0058] The hub member 2 fitted on the input shaft 16 of the
transmission to be rotated integrally with the input shaft 16 is
provided at its outer periphery with a spline portion 36. The
friction plates 3 are fitted in the spline portion 36 having axial
through-holes 37 for an axial sliding movement. Accordingly, a
power inputted from the crankshaft (not shown) of the engine (not
shown) is transmitted to the transmission (not shown) through the
housing 12 through a damper device 44 (described later), clutch
drum 1, wet type multi-plate clutch 30, hub member 2 and input
shaft 16.
[0059] The clutch drum 1 of the wet type multi-plate clutch 30
includes a damper device 44 as a shock absorbing mechanism for
absorbing shock generated during the clutch engagement. The damper
device 44 is constituted by a retainer plate 40 for holding a
spring 49, and a pawl member 42 attached to an outer periphery of
the drum portion 34 of the clutch drum 1 and fitted on the spring
49.
[0060] The input shaft 16 of the transmission to which the power
from the engine is transmitted is provided with an oil supplying
path 54 extending in the axial direction. Hydraulic oil supplied
from a supply source (not shown) is supplied to the hydraulic
chamber 31 through the oil supplying path 54, a gap 95 between the
input shaft 16 and the boss 11 and an axial through hole 56 of the
cylindrical portion 57 of the boss 11 of the housing 12 and then
through an axial through hole 59 formed in the cylindrical portion
32 of the clutch drum 1.
[0061] At an axial one end, the input shaft 16 is provided at its
outer periphery with a spline portion into which a cylindrical
portion 50 of the hub member 2 is spline-fitted. That is to say,
the input shaft 16 can be rotated integrally with the hub member
2.
[0062] A cover member 7 is provided at the open end portion of the
clutch drum 1. An outer diameter edge portion 73 of the cover
member 7 is fitted into the spline portion 39 of the clutch drum 1.
Thus, the cover member 7 is rotated together with the clutch drum
1. The cover member 7 defines a narrow lubricating oil passage 64
between the hub member 2 and the cover member, which lubricating
oil passage 64 is communicated with an oil passage 63 provided in
an outer periphery of the input shaft 16.
[0063] Further, a passage 65 is provided between the housing 12 and
the cover member 7 and an oil discharging path 62 is provided
between a cylindrical portion 12a formed at the inner diameter side
of the housing 12 and the input shaft 16, thereby providing a
passage through which the oil which has lubricated the clutch
portion 30 is discharged toward the transmission. An oil from an
oil pump (not shown) driven through the cylindrical portion 12a of
the housing 12 is temporarily supplied to a hydraulic control
device (not shown) at the transmission side and then is supplied as
operating oil for the starting clutch 10 and a brake portion (not
shown) and a clutch portion (not shown) at the transmission side
and is also supplied to lubricate various parts of the starting
clutch 10 and the transmission.
[0064] In the illustrated embodiment, an outer peripheral edge
portion 73 of the cover member 7 as means for trapping the oil
supplied for the lubrication within the hub member 2 is fitted in
the spline portion 39 of the clutch drum 34, whereby the cover
member is supported to be rotated together with the clutch drum 34.
As can be seen from FIG. 3, by providing the cover member 7, the
wet type multi-plate clutch 30 is disposed within a substantially
enclosed space.
[0065] An intermediate portion 91 extends from an end of the
cylindrical portion 50 of the hub member 2 at the transmission side
in the radial direction and then is bent toward the engine at an
intermediate region and then extends toward the transmission in the
axial direction thereby to form a spline portion 36. Further, an
intermediate portion 90 of the cover member 7 extends in the radial
direction and then is bent toward the transmission at an
intermediate region and then further extends radially outwardly to
form an outer diameter edge portion 73. The intermediate portions
90 and 91 are adjacent to and opposed to each other in the axial
direction to define a narrow passage 64 therebetween. By providing
the cover member 7, the lubricating oil passage 64 for supplying
the lubricating oil can be separated from the lubricating oil
passage 65 for discharging the lubricating oil so that the oil can
be efficiently supplied and discharged.
[0066] As can be seen from FIG. 3, the hub member 2, spline portion
36 and cover member 7 define a space S enclosed at the inner
diameter side of the hub member 2. Accordingly, the oil directed
from the passage lubricating oil 64 toward the outer diameter side
can be supplied efficiently to the clutch portion by the presence
of the space S. Further, in the clutch portion disposed at the
downstream side of the space S, the oil is apt to be trapped by not
providing lubricating oil discharging hole(s) at the outer diameter
side of the clutch drum or by reducing the number of the
discharging holes or reducing sizes of the discharging holes.
[0067] As can be seen from FIG. 3, by providing the cover member 7,
the wet type multi-plate clutch 30 is disposed within a
substantially enclosed space.
[0068] Next, the friction plate used in the various embodiments of
the present invention will be fully explained with reference to
FIG. 4. The friction plate 3 is constituted by adhering a plurality
of friction material segments 74 on an annular steel core plate 20
in an annular fashion by an adhesive. Splines 20a are formed in an
inner periphery of the core plate 20 and the splines 20a are fitted
in the spline portion 36 of the hub member 2.
[0069] A plurality of grooves 76 parallel to a diameter direction
of the core plate and a plurality of grooves 77 perpendicular to
the diameter direction are formed in a surface of the friction
material segment 74 at substantially equidistant intervals. The
grooves 76 and the grooves 77 are formed as recessed grooves by a
pressing operation before or after the friction material segment 74
is secured to the core plate 20. As shown, the grooves 76 are
disposed substantially perpendicular to the grooves 77.
[0070] Between the friction material segments 74, there is provided
a groove 75 disposed in parallel with the diametrical direction of
the core plate 20 i.e. in parallel with the grooves 76. By the
presence of the groove 75, the surfaces of the core plate 20 are
exposed between the friction material segments 74.
[0071] The grooves formed in the friction material segment 74 may
be radial grooves. Further, in place of the segments, an annular
friction material may be secured to the core plate. The friction
material segments or the annular friction material may be secured
to one surface or both surfaces of the core plate 20. If the
friction material is secured to one surface of the core plate, a
friction material may be secured to a surface of another separator
plate 4 opposed to the other surface of the core plate having no
friction material.
[0072] The grooves 75, 76 and 77 must serve to maintain the
fluidity of the lubricating oil and to hold the lubricating oil for
efficient heat exchange. To this end, a total volume ratio of the
grooves 75, 76 and 77 determined by axial depths and widths of the
grooves is selected to about 10% to about 50%. Preferably, the
total volume ratio is about 20% to about 40%. Here, the "total
volume ratio" means a ratio of total volumes of the grooves 75, 76
and 77 to a total volume of the friction material when the annular
friction material is uniformly stuck to the core plate 20.
[0073] In the above-mentioned embodiments of the present invention,
the spring 9 for applying the urging force to the piston 8 to
tighten the wet type multi-plate clutch 30 of the starting clutch
may be, for example, a leaf spring or a wave spring, in place of
the coil spring. Further, the urging force i.e. spring force or the
oil pressure for urging the piston may be set in consideration of
various factors such as a weight of the vehicle, coefficients of
friction of the friction engaging elements of the starting clutch,
surface areas of the friction engaging surface and the like.
[0074] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0075] This application claims priority from Japanese Patent
Application No. 2006-338303 filed Dec. 15, 2006, which is hereby
incorporated by reference herein.
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