192 clutches and power-stop control – Clutches – Fluent material
Reexamination Certificate
2001-05-25
2002-11-05
Binda, Greg (Department: 3679)
192 clutches and power-stop control
Clutches
Fluent material
C464S024000, C464S026000
Reexamination Certificate
active
06474458
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a viscous fluid coupling adapted to drive an accessory device, such as a cooling fan, of an internal combustion engine.
Japanese Utility Model Provisional Publications Nos. 57-204491 and 3-77825 disclose a viscous fluid coupling adapted to a cooling fan for an internal combustion engine. As shown in
FIGS. 21 and 22
, this conventional viscous fluid coupling
100
includes a housing
104
relatively rotatable with a drive shaft
102
, an operation plate
108
dividing a space in the housing
104
into a reservoir
105
and an operation chamber
106
, a rotor
109
disposed in the operation chamber
106
and fixed to the drive shaft
102
and a valve mechanism
111
disposed at an outer peripheral portion of the rotor
109
. The housing
104
is constituted by a housing body member
121
supported by the drive shaft
102
and a cover member
122
fixed to the housing body member
121
. The cover member
122
includes a circular recess portion
123
for defining the operation chamber
105
and a ring-shaped flange portion
125
having a return passage
124
. The operation plate
108
is made of metal and formed into a disc shape. The operation plate
108
is connected to the flange portion
124
of the cover member
122
by means of caulking so as to close an opening of the recess portion
123
of the cover member
122
. A torque transmitting section
110
is constituted by a plurality of annular projections
1
27
concentrically formed on the cover member
122
and a plurality of annular projections
128
concentrically formed on the rotor
109
so that the annular projections
127
and
128
are overlapped with each other.
When the ambient temperature around the housing is low, the communication hole
107
formed on the operation plate
108
is closed by the valve mechanism
111
to stop the flow of the viscous fluid from the reservoir
105
to the operation chamber
106
. Therefore, the torque transmission amount from the rotor
109
to the housing
104
is lowered to stop or rotate a cooling fan in low speed. When the ambient temperature around the housing is high, the communicated hole is opened by the operation of the valve mechanism
111
to allow the viscous fluid to flow from the reservoir
105
to the operation chamber
106
. Therefore, the torque transmission amount from the rotor
109
to the housing
104
is increased to rotate the cooling fan at high speed.
However, this conventional viscous fluid coupling
101
encounters drawbacks. For example, since the torque transmitting section
110
is formed by locating the annular projections
127
and the annular projections
128
, adjacent to each other it is necessary to locate the torque transmitting section
110
on an outer peripheral portion of the cover member
122
. That is, because the operation plate
108
is installed at a central portion of the cover member
122
, it is impossible to locate the annular projections
127
at an inner position corresponding to the operation plate
108
.
Further, since the torque transmitting section
110
is formed at an outer side as compared with an inner surface defining the reservoir
105
, that it, since the reservoir
105
is located at a height which is (gravitationally) lower than that of the torque transmitting section
110
, the torque transmitting section
110
becomes dipped in (viz, becomes at least partially immersed in or coated with) the viscous fluid when the engine stops. This dipping of the torque transmitting section
110
generates a dragging-rotation phenomenon of the cooling fan when the engine is started. Although Japanese Utility Model Provisional Publications Nos. 59-128933 and 1-83925 have proposed another conventional viscous fluid coupling arranged to prevent such a fan dragging-rotation phenomenon, this conventional viscous fluid coupling has generated another problem that the utility of the viscous fluid is degraded.
SUMMARY OF THE PRESENT INVENTION
A viscous fluid coupling according to the present invention is connected to an engine. The viscous fluid coupling comprises a drive shaft connected to a rotation shaft of the engine. A housing is rotatably supported to the drive shaft. An operation plate is set in the housing so as to divide a space defined by the housing into a reservoir and an operation chamber. The operation plate has a communication hole communicating the reservoir and the operation chamber. Viscous fluid is stored in the reservoir and the operation chamber. A rotor is disposed in the operation chamber and is fixed to the drive shaft. A valve mechanism closes and opens the communication hole according to ambient temperature of the housing to control a flow rate of the viscous fluid from the reservoir to the operation chamber. A driven wheel is fixed to the housing so as to be located between the operation plate and the rotor. A torque transmitting section includes a plurality of first annular projections concentrically formed on an outer peripheral portion of the driven wheel and a plurality of second annular projections concentrically formed on an outer peripheral portion of the rotor. The first annular projections are overlappedly adjacent to the second annular projections so as to be fluidly coupled with each other through the viscous fluid.
REFERENCES:
patent: 2337976 (1943-12-01), Davis
patent: 4633994 (1987-01-01), Light
patent: 4790792 (1988-12-01), Bopp
patent: 4913273 (1990-04-01), Mader
patent: 5044477 (1991-09-01), Bojas et al.
patent: 5499706 (1996-03-01), Kawada
patent: 5893442 (1999-04-01), Light
patent: 6085881 (2000-07-01), Robb
patent: 27 18 723 (1977-11-01), None
patent: 28 14 468 (1978-10-01), None
patent: 33 07 566 (1983-09-01), None
patent: 42 05 225 (1992-09-01), None
patent: 42 23 678 (1993-01-01), None
patent: 93 17 085 (1994-02-01), None
patent: 0 070 111 (1983-01-01), None
patent: 0 106 581 (1984-04-01), None
patent: 0 870 943 (1998-10-01), None
patent: 57-204491 (1982-12-01), None
patent: 59-128933 (1984-08-01), None
patent: 1-083925 (1989-06-01), None
patent: 3-077825 (1991-08-01), None
Merriam-Webster's Collegiate Dictionary, 10thed., Merriam-Webster, Inc., Springfield MA, 1997, p. 538.
Fujita Yasuo
Katoh Hirofumi
Kawada Shin-ichi
Ohhara Kenzi
Binda Greg
Foley & Lardner
Unisia Jecs Corporation
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