Power plants – Pressure fluid source and motor – Motor driven by motive fluid of system drives pump...
Reexamination Certificate
1999-05-17
2001-09-11
Lopez, F. Daniel (Department: 3745)
Power plants
Pressure fluid source and motor
Motor driven by motive fluid of system drives pump...
C060S456000, C060S484000
Reexamination Certificate
active
06286308
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a system for driving a cooling fan for blowing air to a cooling object, such as a radiator for an engine coolant, an engine oil cooler, a working fluid oil cooler, a hydraulic pump and so forth of a construction machine, an industrial vehicle and so forth.
BACKGROUND ART
For cooling an engine of a construction machine, an industrial vehicle and so forth, it has been conventional to circulate a coolant for the engine to a radiator, and in conjunction therewith, to blow an air to the radiator by means of a cooling fan.
The foregoing cooling fan is mechanically driven by the engine, or, in the alternative, by a hydraulic motor which is rotated by a discharged pressurized fluid of a hydraulic pump driven by the engine.
Since the conventional cooling fan is driven by utilizing a horse power of the engine, the horse power of the engine is consumed for driving the cooling fan.
Therefore, the present invention is worked out for solving the problem set forth above, and has an object to provide a drive system of a cooling fan.
DISCLOSURE OF THE INVENTION
The first invention is a drive system for a cooling fan, comprising a primary hydraulic pump
2
driven by an engine
1
, an operating valve
4
for supplying a discharged pressurized fluid of the primary hydraulic pump
2
to an actuator
5
, a cooling fan
7
for blowing an air to a cooling object, a first hydraulic rotary machine
8
for rotating the cooling fan
7
, a second hydraulic rotary machine
9
for rotating the cooling fan
7
, a return circuit
10
for supplying a returning pressurized fluid from the operating valve
4
to the first hydraulic rotary machine
8
, and a hydraulic pressure source for supplying pressurized fluid to the second hydraulic rotary machine
9
.
According to the first invention, when the actuator
5
is not actuated, the second hydraulic rotary machine
9
is rotated by the pressurized fluid of the hydraulic pressure source, to thereby rotate the cooling fan
7
. When the actuator
5
is actuated, the first hydraulic rotary machine
8
is rotated by utilizing the returning pressurized fluid. Thus, the cooling fan
7
is rotated by the first and second hydraulic rotary machines
8
and
9
.
Thus, since the cooling fan
7
can be rotated by utilizing the returning pressurized fluid of the actuator
5
, the air blowing performance of the cooling fan
7
can be made large. Also, a consumption of a horse power of the engine can be reduced.
The second invention is a drive system for a cooling fan, wherein a back pressure valve
40
is provided in the return circuit
10
in the first invention, and an upstream side of the back pressure valve
40
is connected to the first hydraulic rotary machine
8
.
By the second invention, the pressure of the pressurized fluid to be supplied to the first hydraulic rotary machine
8
becomes higher than or equal to the set pressure of the back pressure valve
40
. Therefore, even when the pressure of the returning pressurized fluid is low, the first hydraulic rotary machine
8
can be rotated with a drive torque higher than or equal to a predetermined torque, and the air blowing performance of the cooling fan
7
can be set at a value greater than or equal to a predetermined value.
The third invention is a drive system for a cooling fan wherein the back pressure valve
40
in the second invention, is provided with a controller that variably sets the back pressure valve
40
at high pressure when a temperature of the cooling object is high, and at low pressure when the temperature of the cooling object is low.
By the third invention, when the cooling object is at a high temperature, the pressurized fluid of high pressure flows into the first hydraulic rotary machine
8
to make an air blowing ability of the cooling fan
7
high. When the cooling object is at in low temperature, the pressurized fluid of low pressure flows into the first hydraulic rotary machine
8
to make the air blowing ability of the cooling fan
7
low.
By this, the cooling object can be cooled efficiently.
The fourth invention is a drive system for a cooling fan wherein a hydraulic pump/motor
45
is driven by the pressurized fluid of the return circuit
10
in the first invention, the variable displacement type hydraulic pump
46
is mechanically connected to the hydraulic pump/motor to form a pressure converter
44
, and the discharged pressurized fluid of the variable displacement type hydraulic pump
46
is supplied to the first hydraulic rotary machine
8
.
By the fourth invention, since the returning pressurized fluid of high pressure can be supplied to the first hydraulic rotary machine
8
, the air blowing ability of the cooling fan
7
can be made high even when the pressure of the returning pressurized fluid is low.
The fifth invention is a drive system for a cooling fan, wherein the hydraulic pressure source of the first invention is an auxiliary hydraulic pump
3
driven by the engine
1
.
By the fifth invention, the second hydraulic rotary machine
9
can be certainly rotated with the discharged pressurized fluid of the auxiliary hydraulic pump
3
which is driven by the engine
1
.
The sixth invention is a drive system for a cooling fan according to the fifth invention which is further provided with a controller that sets for setting a pressure of the fluid supplied from the auxiliary hydraulic pump
3
to the second hydraulic rotary machine
9
at high pressure when the temperature of the cooling object to be cooled by the cooling fan
7
is high and at low pressure when the temperature is low.
By the sixth invention, the pressure of the pressurized fluid flowing into the second hydraulic rotary machine
9
is set at high pressure when the cooling object is at a high temperature, and at low pressure when the cooling object is at a low temperature. Therefore, when the cooling object is at a high temperature, the air blowing performance of the cooling fan
7
is high and when the cooling object is at a low temperature, the air blowing performance is low.
As set forth above, the cooling object can be cooled efficiently, and the wasting of horse power of the engine
1
can be prevented.
The seventh invention is a drive system for a cooling fan wherein a pressurized fluid inflow side of the first hydraulic rotary machine
8
and a pressurized fluid inflow side of the second hydraulic rotary machine
9
are connected to a tank
12
through a suction valve
11
.
By the seventh invention, when the first and second hydraulic rotary machines
8
and
9
are operated for pumping operation, they suck the fluid from the tank
12
so as not to generate negative pressure in them.
The eighth invention is a drive system for a cooling fan according to the fifth invention wherein the first hydraulic rotary machine
8
is a turbo type rotary machine, the cooling fan
7
is a turbo fan, the second hydraulic rotary machine
9
is a gear type hydraulic motor, the turbo fan is connected to one side portion of the turbo type rotary machine, and the gear type hydraulic motor is connected to the other side portion of the turbo type rotary machine.
By the eighth invention, the cooling fan
7
, the first hydraulic rotary machine
8
and the second hydraulic rotary machine
9
are connected integrally to make them compact.
On the other hand, since the cooling fan
7
is the turbo fan and the first hydraulic rotary machine
8
is the turbo rotary machine, air blowing volume of the cooling fan
7
becomes large while still being compact.
The ninth invention is a drive system for a cooling fan, wherein the hydraulic pressure source in the first invention is a branch circuit
60
connected to a discharge passage
2
a
of the primary hydraulic pump
2
.
By the ninth invention, the second hydraulic rotary machine
9
can be certainly rotated by utilizing the discharged pressurized fluid of the primary hydraulic pump
2
.
The tenth invention is a drive system for a cooling fan, wherein a variable pressure reduction valve
65
is provided in the branch circuit
60
in the nin
Endo Hiroshi
Yoshida Nobumi
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Komatsu Ltd.
Lopez F. Daniel
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