192 clutches and power-stop control – Clutches – Fluent material
Reexamination Certificate
1999-10-29
2001-04-24
Marmor, Charles A. (Department: 3681)
192 clutches and power-stop control
Clutches
Fluent material
C192S058800, C123S041120
Reexamination Certificate
active
06220416
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the improvements of a temperature-sensing, variable-speed fan drive with a fluid coupling, incorporated in a cooling system of an internal combustion engine.
2. Description of the Prior Art
FIG. 9
shows a typical temperature-sensing, variable-speed viscous fan drive with a small fluid coupling partly filled with a special silicone oil. The conventional fan drive (or a fan coupling device)
101
includes a driven housing
104
rotatably supported on a drive shaft
102
by way of a ball bearing
103
, a partition plate
108
dividing the internal space of the housing
104
into a fluid reservoir chamber
105
and a working chamber
106
, a communication port
107
formed in the partition plate
108
in such a manner as to intercommunicate the reservoir chamber
105
and the working chamber
106
, a rotor
109
fixedly connected to the front end of the drive shaft
102
and housed within the working chamber
106
, a torque-transmitting viscous-coupling portion
110
transmitting torque from the rotor
109
to the housing
104
, and a valve mechanism
111
capable of regulating the amount of working fluid flowing from the reservoir chamber
105
via the communication port
107
to the working chamber
106
by adjusting or controlling the opening or size of the communication port
107
depending on the atmospheric temperature in the circumference of the housing
104
. The drive shaft is driven by the engine crankshaft of an internal combustion engine. As seen in
FIG. 9
, the housing
104
is constructed by a housing body
121
rotatably supported on the drive-shaft front end through the ball bearing
103
, and a front cover portion
122
tightly fitted to the front face of the housing
104
. The cover portion
122
has a substantially circular recessed portion
123
formed in its inner peripheral portion to define the reservoir chamber
105
. Also, the cover portion
122
has a ring-shaped flanged portion
125
formed in its outer peripheral portion to define a working-fluid return passage
124
therein. The outermost peripheral portion of the housing
104
, consisting of the housing body
121
and the cover portion
121
, is formed with a plurality of cooling-fan mounting bolt holes for mounting the cooling fan on the housing
104
by means of bolts. The viscous-coupling portion
110
consists of two sets of concentric labyrinth portions
127
and
128
alternately fixed to the flanged portion
125
of the housing and the rotor
109
, with the viscous fluid between them. As is generally known, the previously-noted valve mechanism
111
includes a temperature-sensing bimetallic coil, a valve operating shaft, and a valve portion. When engine cooling requirements are low, such as during cool-weather, intermediate-speed operation, the communication port
107
is fully closed by the valve mechanism
111
to cut off the flow of working fluid from the reservoir chamber
105
to the working chamber
106
in order to block the flow of working fluid into the viscous-coupling portion
110
. Thus, the working fluid is withdrawn from the torque-transmitting, viscous-coupling portion
110
via the return passage
124
into the reservoir chamber
105
. Thus, so less power or torque passes through and the fan speed drops to the minimum. In contrast to the above, when engine cooling requirements are high, such during high temperature, high-speed operation, the communication port
107
is fully opened by the valve mechanism
111
to allow the flow of working fluid from the reservoir chamber
105
to the working chamber
106
. Thus, more working fluid is fed via the communication port
107
toward within the torque-transmitting, fluid coupling portion
110
. More power or torque passes through the coupling portion
110
and thus the fan speed increases, so as to effectively cool an engine cooling-system radiator. One such temperature-sensing, variable-speed viscous fan drive with a small fluid coupling has been disclosed in Japanese Utility-Model Provisional Publication Nos. 57-204491 and 3-77825. On automotive vehicles with an air conditioning system, a sole temperature-sensing, variable-speed fan coupling device is often used for cooling at least two stacked heat exchangers, namely a cooling-system radiator, and an air-conditioner condenser usually located in front of the radiator. On cars with two stacked heat exchangers, there is the following problem. If the air conditioning system comes into operation under a particular condition where engine cooling requirements are high, as in the summer, and the engine begins to run or is idling, it is difficult to adequately cool the air-conditioner condenser, for the reasons set out below.
That is, when the air conditioning system comes into operation under the previously-noted particular condition, air temperature in the circumference of the air-conditioner condenser rises, and thus refrigerant pressure begins to rise. Suppose the atmospheric temperature in the circumference of the cooling-fan housing does not yet rise. In such a case, the cooling fan never rotates. The condenser cannot be cooled satisfactorily, thus resulting in reduction in the air conditioning system efficiency (the heat exchanging efficiency). To avoid this (to ensure a required airflow through the condenser), it is possible to add auxiliary fans. This induces a more complicated construction of the system, and increases production costs.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a temperature-sensing, variable-speed fan drive with a fluid coupling which avoids the aforementioned disadvantages of the prior art.
It is another object of the invention to provide a sole temperature-sensing, variable-speed fan drive with a fluid coupling, which is capable of satisfactorily cooling at least two stacked heat exchangers, such as a cooling-system radiator and an air-conditioner condenser both located in front of an internal combustion engine, by means of the sole fan drive with the fluid coupling, even when an air-conditioning system comes into operation under a particular condition where engine cooling requirements are high and the engine begins to run or is idling.
In order to accomplish the aforementioned and other objects of the present invention, a temperature-sensing, variable-speed fan drive with a fluid coupling filled with working fluid, for cooling an engine cooling-system heat exchanger and an air-conditioner condenser stacked in front of the cooling-system heat exchanger, comprises a fan housing rotatably supported on a drive shaft having a driven connection with an engine crankshaft, a partition plate dividing an internal space of the fan housing into a working-fluid reservoir chamber and a working chamber, a first communication port formed in the partition plate to communicate the working-fluid reservoir chamber with the working chamber, a second communication port formed in the partition plate and different from the first communication port to communicate the working-fluid reservoir chamber with the working chamber, a rotor fixedly connected to the drive shaft, a torque-transmitting viscous-coupling portion disposed between the rotor and the fan housing to transmit torque from the rotor to the fan housing via the working fluid, a first valve mechanism which adjusts an opening of the first communication port in response to an atmospheric temperature in a circumference of the fan housing, and a second valve mechanism which adjusts an opening of the second communication port in response to a refrigerant pressure in the air-conditioner condenser. It is preferable that the first valve mechanism provides an atmospheric-temperature versus volumetric capacity characteristic that the first communication port begins to open when the atmospheric temperature in the circumference of the fan housing reaches a predetermined lower threshold value, and that the opening of the second communication port increases linearly as the atmospheric temperature in the circumfere
Katoh Hirofumi
Matsuya Tatsuyuki
Foley & Lardner
Marmor Charles A.
Rodriguez Saul
Unisia Jecs Corporation
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