192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2002-03-12
2004-01-13
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C092S13000R, C192S085060, C267S158000
Reexamination Certificate
active
06675944
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a clutch of an automatic transmission, and more particularly, to a return apparatus of a clutch piston of an automatic transmission.
BACKGROUND OF THE INVENTION
A multi-plate clutch is structured having a plurality of alternating clutch plates and disks, and is used to transmit power in motorcycles and automatic transmissions of vehicles. The conventional multi-plate clutch assembly, with reference to
FIG. 5
, includes a plurality of clutch plates
104
, which are mounted substantially in parallel within slots of an inner slotted portion
102
of a clutch retainer
100
, and a plurality of clutch disks
110
, which are mounted between the clutch plates
104
within slots of an outer slotted portion
108
of a hub
106
. That is, the clutch plates
104
and the clutch disks
110
are inserted partially within the slots of the inner slotted portion
102
of the clutch retainer
100
and the outer slotted portion
108
of the hub
106
, respectively.
A piston
112
is mounted in an area defined by the clutch retainer
100
, and a hydraulic pressure chamber
114
is formed between the piston
112
and the clutch retainer
100
. A return spring
116
, which is a compression spring, is provided on a side of the piston
112
opposite to that where the hydraulic pressure chamber
114
is formed to provide a constant biasing force to the piston
112
in a direction toward the hydraulic pressure chamber
114
.
With the supply of a sufficient hydraulic pressure to the hydraulic pressure chamber
114
, the piston
112
overcomes an elastic force of the return spring
116
such that the piston
112
moves in a direction toward the clutch plates
104
and the clutch disks
110
to compress the same, thereby engaging the multi-plate clutch to allow for the transmission of power. If the hydraulic pressure is then exhausted from the hydraulic pressure chamber
114
, the piston
112
moves in the opposite direction as a result of the biasing force of the return spring
116
. This removes the force applied to the clutch plates
104
and the clutch disks
110
by the piston
112
so that the transmission of power is discontinued.
However, the exhaust of hydraulic fluid is often incomplete. That is, although the hydraulic pressure in the path between a hydraulic pressure control apparatus and the hydraulic pressure chamber
114
is fully exhausted, part of the fluid in the hydraulic pressure chamber
114
is not exhausted as a result of a centrifugal force generated by the rotation of the clutch, thereby generating a centrifugal force hydraulic pressure. In the case where the clutch is rotating at a high speed, the centrifugal force hydraulic pressure may maintain engagement of the clutch.
FIG. 5
shows two types of clutch return mechanisms according to the prior art, one of which is, as shown in an upper-half part, a balance piston type, and the other of which is, as shown in a lower-half part, a check ball type.
According to the balance piston type, a balance piston
118
is mounted inwardly from the piston
112
as shown in the upper part of the example of a conventional multi-clutch assembly of
FIG. 5
, and the return spring
116
is interposed between the piston
112
and the balance piston
118
. Also, an opposing hydraulic pressure is supplied to a space between the piston
112
and the balance piston
118
such that the opposing hydraulic pressure enables the piston
112
to return.
According to the check ball type, with reference to the lower part of the example of a conventional multi-clutch assembly of
FIG. 5
, a check ball
120
is mounted at an outer extremity portion of the piston
112
, with this area of the piston
112
and the adjacent member being formed in such a manner as to allow operation of the check ball
120
. Various forces act on the check ball
120
including the force of the hydraulic pressure, centrifugal force resulting from the rotation of the multi-plate clutch, and a buoyancy force provided by the fluid used to create hydraulic pressure. If a rotational speed of the clutch is increased, the centrifugal force acting on the check ball
120
overcomes the centrifugal force hydraulic pressure to create the flow of fluid, that is, to enable exhaust of the remaining fluid.
However, in the case of the first example above in which the balance piston
118
is used, to effectively offset the centrifugal force hydraulic pressure, an inner diameter of the balance piston
118
must be smaller than an inner diameter of the piston
112
. As a result, the size of the transmission is increased.
Further, with respect to the application of the check ball
120
, it is difficult to design the check ball
120
and maintain the quality of the same to meet the precise design parameters. It is also difficult to fabricate the check ball
120
to the precise design parameters, as the surfaces of the check ball
120
and its contacting surface must be fabricated with exactitude.
SUMMARY OF THE INVENTION
According to the present invention there is provided a return apparatus for a clutch piston of an automatic transmission which includes a return spring, the elastic force of which increases as the rotational speed of the clutch piston increases such that the clutch piston is prevented from engaging when hydraulic pressure is released. The return apparatus according to the invention further includes a spring support rotating at a same speed as the clutch piston, with the return spring abutted at an end against the spring support and exerting an elastic force on the clutch piston, the elastic force increasing as the clutch piston rotational speed increases.
The return spring of the invention preferably includes a plane spring plate curved convexly at its central portion, in a radial direction with respect to the rotation axis of the clutch piston, and a mass unit disposed at the curved central portion, where the return spring is abutted against the spring support at an end of the plane spring plate. The opposite end of the plane spring plate is connected to the clutch piston. The mass unit is, preferably, cylindrically shaped.
The return spring may also comprise a central portion having a predetermined length and mass, and a pair of elastic fins extending in a radial direction with respect to the rotation axis of the clutch piston, at a predetermined angle on opposite sides of the central portion. Also a distal end of one of the elastic fins is preferably abutted against the spring support and a distal end of the other elastic fin is abutted against the clutch piston.
In a further aspect of the invention a return spring for a clutch piston of an automatic transmission comprises a v-shaped body with a force generating mass disposed at the apex of the body. The v-shaped body has two resilient arms configured to bear in opposition against a spring support and the clutch piston. The force generating mass disposed at the apex is configured and dimensioned to exert a spreading force on the resilient arms in response to rotation of the clutch piston sufficient to overcome any centrifugal force hydraulic pressure acting on the piston. In a preferred embodiment, the force generating mass is formed integrally with the v-shaped body.
In another alternative embodiment of the invention, a clutch piston system for an automatic transmission includes a clutch piston acting on at least one clutch plate in response to applied hydraulic pressure, and centrifugal force means for returning the clutch piston to a non-acting position in response to discontinued hydraulic pressure. In a preferred embodiment, the centrifugal force means comprises support means rotating with the clutch piston and centrifugal force biasing means bearing against the support means. The centrifugal force biasing means acts on the clutch piston with increasing force proportional to rotational speed of the clutch piston. In one preferred embodiment, the centrifugal force biasing means comprises a v-shaped body and a force generating mass. The v-shaped body defines an apex and two res
Bonck Rodney H.
Hyundai Motor Company
Pennie & Edmonds LLP
LandOfFree
Return apparatus for a clutch piston of an automatic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Return apparatus for a clutch piston of an automatic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Return apparatus for a clutch piston of an automatic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3251461