Centrifugal friction clutch for automatic transmission

192 clutches and power-stop control – Clutches – Operators

Reexamination Certificate

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Reexamination Certificate

active

06422371

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a centrifugal friction clutch for an automatic transmission, including a friction clutch unit and centrifugal weights capable of engaging and disengaging the friction clutch unit according to centrifugal force acting thereon.
2. Description of the Related Art
FIG. 16
shows a prior art centrifugal friction clutch for an automatic transmission, disclosed in JP-A No. Hei 9-14436. Referring to
FIG. 16
, an automatic transmission
01
is provided with a planetary gear including an input shaft
02
, an output shaft
03
coaxially supported for rotation on the input shaft
02
, a ring gear
05
, which is a helical gear, splined to the input shaft
02
, a sun gear
06
, which is a helical gear, connected to a one-way clutch by a rotating member
09
, a carrier
08
formed integrally with the output shaft
03
, and planet pinions
07
, which are helical gears, supported on the carrier
08
. A pressure receiving member
08
a
is connected to the carrier
08
formed integrally with the output shaft
03
. A clutch cover
010
is supported on the pressure receiving member
08
a
so as to be axially movable relative to the pressure receiving member
08
a
and to rotate together with the pressure receiving member
08
a
. The clutch cover
010
has a cylindrical wall
010
a
surrounding the pressure receiving member
08
a
, an outer end wall
010
b
formed at one end of the cylindrical wall
010
a.
A pressure member
011
is fitted in the cylindrical wall
010
a
opposite to the pressure receiving member
08
a
and is retained in the cylindrical wall
010
a
by a snap ring
012
. A plurality of friction disks
012
are interposed between the pressure receiving member
08
a
and the pressure member
011
and are mounted on the ring gear
05
so as to be axially movable relative to the ring gear
05
and to be rotatable together with the ring gear
05
, and a plurality of clutch disks
013
are fitted in the cylindrical wall
010
a
of the clutch cover
010
so as to be axially movable relative to the cylindrical wall
010
a
and to be rotatable together with the cylindrical wall
010
a
. The friction disks
012
and the clutch disks
013
are arranged alternately. A plurality of rectangular openings
010
c
are formed in a portion of the cylindrical wall
010
a
of the clutch cover
010
near the outer end wall
010
b
in a circumferential arrangement, and centrifugal weights
015
are fitted in the rectangular openings
010
c
. Coned disk springs
016
and an annular bearing member
017
are interposed between the outer end wall
010
b
of the clutch cover
010
and the pressure receiving member
08
a
so that base portions
015
a
of the centrifugal weights
015
are held between the annular bearing member
017
and the outer end wall
010
b.
When an engine by which the automatic transmission is driven is stopped, the centrifugal weights
015
are held at positions indicated by two-dot chain lines in
FIG. 16
by the coned disk springs
016
so as to engage a centrifugal friction clutch lightly, in which the pressure member
011
is pressed lightly against the pressure receiving member
08
a.
When the engine operates at a very low engine speed, the driving torque of the engine is transmitted to the planetary gear, and the pressure receiving member
08
a
and the pressure member
011
are spaced apart by the thrust produced by the helical gears of the planetary gear. Consequently, the friction disks
012
and the clutch disks
013
interposed between the adjacent friction disks are separated and the centrifugal friction clutch is disengaged.
When the engine operates at high engine speeds, the centrifugal weights
015
are turned radially outward to positions indicated by continuous lines in
FIG. 16
by centrifugal force. Consequently, the base portions
015
a
of the centrifugal weights
015
presses the annular bearing member
017
to press the coned disk springs
016
against the pressure receiving member
081
which is restrained from axial movement. The resilience of the coned disk springs
016
acts through the base portions
015
a
of the centrifugal weights
015
on the outer end wall
010
b
of the clutch cover
010
. Consequently, the clutch cover
010
pushes the pressure member
011
to the right, as viewed in FIG.
16
through the snap ring
012
, the distance between the pressure receiving member
08
a
and the pressure member
011
is reduced, the friction disks
012
are pressed against the clutch disks
013
and thereby the centrifugal friction clutch is engaged.
When changing the friction disks
012
and the clutch disks
013
of the centrifugal friction clutch for maintenance, the snap ring
012
is removed, the pressure member
011
is removed, and then the friction disks
012
and the clutch disks
013
are removed. The clutch cover
010
is released from the pressure receiving member
08
a
when the snap ring
012
is removed. Consequently, the coned disk springs
016
are unloaded, the centrifugal weights
015
fall out of the clutch cover
010
. Therefore, troublesome work for assembling the centrifugal weights
015
and the clutch cover
010
is necessary when reassembling the centrifugal friction clutch, which makes maintenance more troublesome.
The present invention has been made in view of such a problem and it is therefore an object of the present invention to provide a centrifugal friction clutch for an automatic transmission, capable of being easily disassembled and assembled for maintenance.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a centrifugal friction clutch for an automatic transmission includes an input member; friction elements supported on the input member so as to be axially movable and to be rotated together with the input member; an output member; a clutch cover supported on the output member so as to be axially movable relative to the output member and to rotate together with the output member; clutch elements supported on the clutch cover so as to be axially slidable; centrifugal weights disposed at predetermined positions on the clutch cover; spring members holding the centrifugal weights in place; and first retaining means put in place on the clutch cover to press the friction members and the clutch members against each other so that power can be transmitted when the centrifugal weights are displaced by centrifugal force to move the clutch cover relative to the output member; wherein a first spring bearing member placed in contact with one end of each of the spring members urges the centrifugal weights toward their respective predetermined initial positions, and a second spring bearing member placed in contact with the other end of each of the spring members is held in place on the clutch cover by second retaining means engaging the clutch cover.
The spring members are held between the first and the second spring bearing member supported on the clutch cover so as to bias the centrifugal weights toward their respective predetermined initial positions, i.e., positions where the centrifugal weights are held by the spring members when the centrifugal friction clutch is assembled. Thus, the first and the second spring bearing members, the spring members and the centrifugal weights are assembled in a unit on the clutch cover. Therefore, the members assembled in a unit on the clutch cover d not come apart even if the clutch cover is disengaged from the output member by removing the first retaining means, the friction elements and the clutch elements are removed for maintenance or the like. Thus, the centrifugal friction clutch can be easily assembled and disassembled.
Preferably, the second retaining means is formed integrally with the second spring bearing member. When the second retaining means is formed integrally with the second spring bearing member, the number of component parts is reduced and assembling work is facilitated.
Preferably, the second spring bearing member is not in contact with the output member and is sup

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