JP2899919B2 - Driving method of cooling fan - Google Patents

Description

The present invention relates to a method for driving a cooling fan in an automobile.

[Prior Art] FIG. 2 is a system diagram showing a conventional driving device for a cooling fan in a large vehicle or the like, in which a hydraulic pump 1 driven by an engine (not shown) is connected to a discharge pipe 1b. The hydraulic motor 2 is linked to a cooling fan 2b for a radiator installed at a position distant from the engine, the discharge line 2c of the hydraulic motor 2 is connected to the reservoir 7, and the discharge line A relief valve 8 is provided in 1b, an outlet line of the relief valve 8 is opened to the reservoir 7, and a check valve 2a is provided in parallel with the hydraulic motor 2.

The operation of the conventional cooling fan driving device shown in FIG. 2 is as follows.

When the engine is driven, the hydraulic pump 1 sucks hydraulic oil from the reservoir 7, and the sucked hydraulic oil is pumped to the hydraulic motor 2 to drive the hydraulic motor 2, whereby the cooling fan 2b rotates. Then, the air flow generated by the rotation cools the water in the radiator.

In this case, since the hydraulic pump 1 is a fixed displacement hydraulic pump, the flow rate of the hydraulic oil discharged to the discharge pipe 1b per unit time is proportional to the rotation speed of the engine. Since the hydraulic motor 2 is also a fixed displacement type, the rotation speed of the cooling fan 2b driven by the hydraulic motor 2 is proportional to the flow rate per unit time from the hydraulic pump 1, that is, the rotation speed of the engine.

The driving torque at which the hydraulic motor 2 drives the cooling fan 2b is proportional to the square of the rotation speed of the cooling fan 2b, and the driving horsepower of the cooling fan 2b is proportional to the product of the rotation speed and the driving torque.

Therefore, the required horsepower of the cooling fan 2b is proportional to the cube of the rotational speed, and the required horsepower reduces the power transmission efficiency by 10%.
If it is set to 0%, since the engine is equivalent to the required horsepower for driving the hydraulic pump 1, the engine consumes the drive horsepower proportional to the cube of the engine rotation speed for driving the cooling fan 2b. Will be.

[Problems to be Solved by the Invention] As described above, the conventional cooling fan driving device is a device for cooling the generated heat of the engine absorbed by the water jacket of the engine when the engine is driven in the radiator. Is what it is.

Therefore, when the engine is driven, that is, when the vehicle is driven, the driving horsepower proportional to the cube of the rotation speed of the engine is consumed for cooling the cooling water in the radiator as described above. The engine drives the cooling fan 2b even when the engine is braked because of the configuration of the device.

Therefore, even at the time of the engine braking, the driving horsepower of the cooling fan 2b is generated in proportion to the cube of the engine rotation speed, thereby enhancing the engine braking capability.

However, the improvement of the engine braking capacity by the driving of the cooling fan is, as described above, three engine speeds.
Since it is proportional to the power, the engine speed cannot be improved unless the engine rotation speed is set to a considerably high value.

Conversely, at the time of engine braking, if the rotation speed of the engine, that is, the rotation speed of the cooling fan 2b is kept high in order to set the engine brake to such a large value, the radiator water temperature may be overcooled. is there.

An object of the present invention is to provide a method of driving a cooling fan that can improve engine braking performance even when the engine speed is relatively low.

[Means for Solving the Problems] (1) The invention according to claim 1 wherein a hydraulic motor driven by discharge pressure oil from a hydraulic pump driven by an engine operates an air-cooling fan of a radiator for cooling cooling water of the engine. In the hydraulic drive in which the pressure setting means is provided in the discharge pipe line from the hydraulic pump driven by the hydraulic pump, the following method of driving the cooling fan is characterized.

That is, (a) at the time of normal running, the cooling fan is driven by the discharge pressure oil from the hydraulic pump as it is in the conventional case, and (b) at the time of engine braking, the discharge line from the pressure setting means to the hydraulic motor To increase the driving load of the engine.

This is because even when the engine speed is low, the discharge pressure of the hydraulic pump increases to the set pressure of the pressure setting means due to the restriction of the discharge pipe regardless of the rotational speed. The increase in the engine load due to the increase means that the engine braking capability is greatly improved.

In this case, the setting pressure of the pressure setting means may be a variable setting linked to the engine brake operation.

(2) Invention of Claim 2 In addition to the invention of Claim 1, at the time of the engine braking, the discharge pipe is narrowed to increase the hydraulic pressure of the hydraulic pump discharge pipe, and the increased pressure oil It is characterized in that another hydraulic motor that is linked to is driven.

That is, in the first aspect, the hydraulic energy increased during the engine braking is discarded from the pressure setting means. In the second aspect, the generator is driven by another hydraulic motor using the hydraulic energy. It is characterized in that energy is recovered.

(3) The invention of claim 3 The pressure setting means in claim 1 is pressure setting means whose pressure setting is adjusted by the radiator water temperature. At the same time, it is characterized in that the set pressure of the pressure setting means is increased irrespective of the radiator water temperature.

That is, when the radiator water temperature is low, the pressure setting means whose pressure setting is adjusted by the radiator water temperature sets the pressure setting means to a low pressure to reduce or stop the rotation speed of the cooling fan 2b. However, at the time of engine braking, even if the radiator water temperature is low, the pressure setting value of the pressure setting means is increased to increase the engine braking capacity.

[Examples] Hereinafter, the present invention will be described based on examples.

FIG. 1 is a system diagram showing a cooling fan driving device required to carry out a driving method of a cooling fan according to the present invention. A hydraulic pump 1 driven by an engine (not shown) has a discharge line. 1b, check valve
1a, connected to the hydraulic motor 2 via the switching valve 3 and the inlet line 2d, and the hydraulic motor 2 is interlocked with the cooling fan 2b for the radiator installed at a position away from the engine, and the discharge line of the hydraulic motor 2 2c communicates with the reservoir 7, the discharge line 1b is provided with a first relief valve 4, and the pilot line 4b in the relief valve 4 is provided with a throttle passage 4c and a second relief valve.
4b, which communicates with the reservoir 7 via the pilot line 4b.
The on / off valve 6 connected to the reservoir 7 is provided in parallel with the relief valve 4a as a bypass circuit.
And a check valve 2a is provided in parallel.

The line 1c connecting the check valve 1a and the switching valve 3 is connected to the hydraulic pump motor 5 via the check valve 5a and the inlet line 5c, and the discharge line 5d of the hydraulic pump motor 5 communicates with the reservoir 7. The branch line 3b from the switching valve 3 communicates with the inlet line 5c of the hydraulic pump motor 5, and the hydraulic pump motor 5 is linked to the motor generator 5b.

The operation of the above embodiment of the present invention will be described below.

In a normal state, that is, when the water temperature in the water jacket of the engine is at an appropriate temperature and the vehicle is in a driving and running state, the solenoid 3a in the switching valve 3 is turned off, and the solenoid in the on / off valve 6 is turned off. 6a is turned on (on), the switching position of the switching valve 3 is set to 3B, and the on / off valve 6 is closed.

In this state, hydraulic oil pumped from the reservoir 7 from the hydraulic pump 1 driven by the engine,
The hydraulic motor 2 is pressure-fed to the hydraulic motor 2 through the discharge line 1b, the check valve 1a, the line 1c, the switching position 3B, and the inlet line 2d. The hydraulic oil that worked in 2 is the discharge line 2c
And returns to the reservoir 7 via.

In this case, the relief valve 4a sets the set pressure of the relief valve 4, and the set pressure of the relief valve 4 is set to the discharge line 1b.
Is the highest set pressure.

Here, the operating oil pressure in the inlet line 2d is
And the drive torque is proportional to the square of the rotation speed of the cooling fan 2b as described above. Therefore, in this state, as in the conventional case, the discharge pipe line 1b and the pipe line are proportionally proportional to the square of the rotation speed of the cooling fan 2b or the hydraulic pump 1 until the pressure set by the relief valve 4 is reached. The working oil pressure of the passage 1c and the inlet conduit 2d changes.

Further, the rotation of the cooling fan 2b thus driven generates an airflow in the radiator, and the airflow cools the water flowing in the radiator.

In this case, each of the check valves 5a and 2a is closed by hydraulic pressure generated in the pipeline 1c or the inlet pipeline 2d.

When the rotation speed of the engine is rapidly reduced from the driving state of the hydraulic pump 1, the hydraulic motor 2 and the cooling fan 2b rotate by the conventional rotational inertia.
The inlet line 2d attempts to lower the pressure with respect to the discharge line 2c.

However, when the pressure of the inlet line 2d became equal to or less than the pressure of the discharge line 2c, the hydraulic oil on the discharge line 2c was discharged by the check valve.
The hydraulic motor 2 and the cooling fan 2b perform a freewheel operation while being replenished to the inlet line 2d through the line 2a.

When the radiator water temperature is still lower than the normal state, there is no need to drive the cooling fan 2b to send cooling air to the radiator. Therefore, in such a state where the radiator water temperature is still low, the solenoid 6a
Is turned off, and the on / off valve 6 is opened.

This means that the pilot line 4b
Is opened to the atmospheric pressure of the reservoir 7 via the on / off valve 6, and the set pressure of the relief valve 4 is set to the pressure of the pilot line 4b, that is, the atmospheric pressure.

As a result, in this state, the pressure of the discharge pipe 1b becomes atmospheric pressure, the cooling fan 2b is not driven, and the hydraulic pump 1 is in a no-load state.

When the vehicle requires engine braking with respect to the driving state of the engine, the following operation is performed.

Normally, when engine braking is required after the start of driving of the vehicle, the radiator water temperature is already at an appropriate temperature, so the solenoid 6a is turned on and the on / off valve 6 is turned on.
Is closed, and the set pressure of the relief valve 4 is a high value.

In this state, when the accelerator pedal of the engine is returned to zero, or in response to an engine brake instruction signal, the solenoid 3a is turned on, and the switching position of the switching valve 3 is set to 3A.

As a result, the pressure oil discharged from the hydraulic pump 1 is discharged to the discharge line 1b, the check valve 1a, the line 1c and the switching position.
The hydraulic pump motor 5 is pumped from the branch line 3b to the inlet line 5c via 3A to drive the hydraulic pump motor 5, and the motor-generator 5b is driven as a generator. Not charged to battery.

As described above, the hydraulic pump 1 applies a drive load to the engine, and the hydraulic energy generated during the drive is
The electric power is converted into electric energy by the motor generator 5b and collected by the battery, and the driving load improves the engine braking capacity of the engine.

In this case, the switching position in the switching valve 3
3A has a restriction in a passage communicating from the pipe 1c to the inlet pipe 2d.

 This means the following.

If the cooling fan 2b has been driven at a relatively high speed until now, and if the supply of pressure oil to the inlet line 2d is completely stopped to suddenly enter the engine brake, the rotational inertia of the hydraulic motor 2 As a result, the inlet line 2d becomes a sudden negative pressure.

In this case, as described above, the existence of the check valve 2a causes the hydraulic motor 2 to perform a freewheel operation.

However, at that time, if the supply of the pressure oil from the pipe line 1c is completely stopped, the operating oil pressure in the inlet pipe line 2d becomes too low only by the presence of the check valve 2a, and the freewheel action may be insufficient. is there.

For this reason, a throttle flow path for partially supplying oil from the pipe 1c side to the inlet pipe 2d side is provided between the pipe 1c and the inlet pipe 2d at the switching position 3A. .

When the engine brake is required, even if the radiator water temperature is too low as described above, the on / off valve 6 gives priority to the engine brake, and in this case, the solenoid 6a is turned on to release the relief. Valve 4
Is set to a regular high set pressure so that the engine brake is applied.

Further, the energy charged in the battery is reused as follows when the vehicle is accelerated.

When the vehicle is accelerating, the switching valve 3 is set to the switching position 3B, the on / off valve 6 is set to the open state, the motor generator 5b is set to the state of the electric motor, and the motor is driven by the electric power in the charged battery.・ Drive the generator 5b.

As a result, the set pressure of the relief valve 4, that is, the set pressure of the discharge line 1b becomes the same atmospheric pressure as that of the reservoir 7,
The hydraulic pump motor 5 performs a pumping operation by driving the motor generator 5b, and the hydraulic pump motor 5 discharges hydraulic oil from the reservoir 7 from the discharge line 5d to the inlet line 5c, and the discharged pressure oil is a check valve. 5a is pushed open, and the hydraulic motor 2 is further driven via the conduit 1c, the switching position 3B and the inlet conduit 2d, whereby the cooling fan 2b sends cooling air to the radiator in the same manner as described above. Become.

In this case, the discharge pipe 1b is at the atmospheric pressure as described above, and the discharge hydraulic pressure from the hydraulic pump motor 5 is generated on the pipe 1c side. Therefore, the check valve 1a is closed, and the check valve 2a is It is closed by the hydraulic pressure generated in the pipeline 2d.

By the above operation, the driving of the cooling fan 2b does not use the energy from the engine, that is, the hydraulic pump 1 is not loaded and the cooling fan 2b is driven by the electric energy of the battery.
Is driving.

Therefore, when accelerating the car, the cooling fan
Since the engine 2b is driven by the engine, there is a margin in the output of the engine, and the engine can effectively accelerate the vehicle with the margin.

In the above embodiment, the first relief valve 4, the second relief valve 4a, and the on / off valve 6 are, as described above,
It serves as pressure setting means for setting a set pressure in the discharge pipe line 1b. That is, the maximum pressure in the discharge pipeline 1b is selectively set to either a predetermined allowable maximum pressure or atmospheric pressure.

However, this pressure setting means may continuously change the set pressure of the pilot line 4b in the relief valve 4 in an analog manner by using an electromagnetic proportional control valve.

Further, the pressure setting means may have a fixed pressure as in a conventional relief valve 8.

However, when the pressure setting means can be adjusted stepwise or in an analog manner, even when the engine speed is the same during the above-described engine braking,
There is an advantage that it is possible to control the engine braking ability by continuously changing the pressure load generated in the hydraulic pump 1.

In the embodiment shown in FIG. 1, the hydraulic pump motor 5 recovers the load power of the hydraulic pump 1 during engine braking.

However, conventionally, at the time of engine braking that does not require radiator cooling, the cooling fan 2b is driven to consume the driving energy without recovering energy.

In the present invention, the pipeline 1c is squeezed at the time of the engine braking, and the engine braking is applied more than before even in a state where the engine rotation speed is low. Therefore,
Just from the purpose of improving the engine braking capacity,
The energy recovery is not always necessary.

Further, the engine brake energy is converted into electric energy and collected, and the recovered energy is reused when the vehicle is accelerated. However, this electric energy is not necessarily reused for accelerating the vehicle. May be used for electric power utilization.

[Effects of the Invention] As is clear from the above description, the effects of the present invention are as follows.

(1) According to the first aspect of the present invention, in the hydraulic drive device for the cooling fan, the discharge resistance of the hydraulic pump 1 is reduced to increase the load resistance of the engine irrespective of the engine rotational speed. It is possible to improve the braking ability.

(2) In the invention of the second aspect, in addition to the effect of the first aspect, converting and recovering high hydraulic energy generated by narrowing the discharge pipeline of the hydraulic pump 1 into electric energy in the first aspect is not limited to that. The recovered energy can be effectively used for the brake energy.

(3) In the invention of claim 3, the pressure setting means provided in the discharge pipe of the hydraulic pump 1 in claim 1 is configured so that when the radiator water temperature is low, the set value can be set to the atmospheric pressure. Cooling fan 2b when water temperature is low
, The radiator water temperature can be effectively increased.

Further, in the case of claim 3, since the set pressure of the pressure setting means can be increased at the time of engine braking, the discharge pipeline of the hydraulic pump 1 can be narrowed at the same time as the engine braking, and the pressure setting means of the pressure setting means can be reduced. By increasing the set pressure, it is possible to improve the engine braking capability.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a hydraulic drive device of a cooling fan required to carry out a method of driving a cooling fan according to the present invention, and FIG. 2 is a diagram showing a conventional hydraulic drive device of a cooling fan. This is shown in the figure. The main symbols used in the examples are as follows. 1: hydraulic pump, 1b ... discharge line, 2: hydraulic motor, 2b: cooling fan, 3: switching valve, 4 and 4a: relief valve, 5: hydraulic pump motor, 5b: motor generator.

Claims (3)

(57) [Claims] 1. A hydraulic motor driven by discharge pressure oil from a hydraulic pump driven by an engine drives an air-cooling fan of a radiator for cooling a cooling water of the engine, and the hydraulic motor drives a discharge pipe from the hydraulic pump. In the hydraulic drive provided with the pressure setting means, during engine braking, the discharge pipe between the pressure setting means and the hydraulic motor is narrowed to increase the driving load of the engine. A method of driving a cooling fan, wherein the throttle is opened and the cooling fan is driven by pressure oil discharged from the hydraulic pump. 2. The driving of the cooling fan according to claim 1, wherein at the time of engine braking, another hydraulic motor linked to the generator is driven by the pressure oil generated between the hydraulic pump and the pressure setting means. Method. 3. A hydraulic motor driven by discharge pressure oil from a hydraulic pump driven by an engine drives an air-cooling fan of a radiator for cooling a cooling water of the engine, and the hydraulic motor is connected to a discharge line from the hydraulic pump. In a hydraulic drive provided with pressure setting means for adjusting the pressure setting according to the radiator water temperature, at the time of engine braking of the engine, the discharge pipe line from the pressure setting means to the hydraulic motor is throttled and the pressure setting means The set pressure of the engine is also increased to increase the driving load of the engine, and during normal driving, the throttle of the discharge pipe is opened, and the cooling fan is driven by the discharge pressure oil from the hydraulic pump. Characteristic cooling fan driving method.