JPH04112916A - Method for driving cooling fan - Google Patents

Abstract

PURPOSE:To improve the capacity of an engine brake in a hydraulic pump driven by pressurized oil discharged from an engine driven hydraulic pump for driving a cooling fan by throttling a discharge pipe line in the engine brake to improve an engine drive load. CONSTITUTION:Since a change-over valve 3 is set to a change-over position 3B and an on/off valve 6 is closed in the normal condition, working oil pumped up from a reservoir 7 by an engine driven hydraulic pump 1 is forced through a discharge pipe line 1b to a hydraulic motor 2 to rotate a cooling fan 2b. On the other hand, when a solenoid 3a is excited by returning an accelerator pedal of the engine to zero for example to set the change-over valve 3 to a change-over position 3A, pressurized oil is forced from a branch pipe line 3b to a hydraulic pump motor 5 to drive a motor generator 5b as a generator so that a drive load is given to the engine to improve the capacity of an engine brake.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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 cooling fan drive device for a large vehicle, etc. A hydraulic pump 1 driven by an engine (not shown) has a discharge pipe 1b. The hydraulic motor 2 is connected to a radiator cooling fan 2b installed at a position away from the engine, and the hydraulic motor 2 is connected to a hydraulic motor 2 via a discharge pipe 2.
C communicates with the reservoir 7, the discharge pipe lb is provided with a relief valve 8, the outlet pipe of the relief valve 8 is open 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 drive 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 sent under pressure to the hydraulic motor 2 to drive the hydraulic motor 2, and this drive causes the cooling fan 2b to rotate. 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 into the discharge pipe 1b per unit time is proportional to the rotational speed of the engine. In addition, since the hydraulic motor 2 is also a fixed displacement type, the hydraulic motor 2
The rotational speed of the cooling fan 2b driven by is proportional to the amount of housing per unit time from the hydraulic pump 1, that is, the rotational speed of the engine.

Further, the driving torque by which the hydraulic motor 2 drives the cooling fan 2b is proportional to the square of the rotational speed of the cooling fan 2b, and the driving horsepower of the cooling fan 2b is proportional to the product of its rotational speed and its driving torque.

Therefore, the required horsepower of the cooling fan 2b is proportional to the cube of its rotation speed, and the required horsepower increases the power transmission efficiency by 10
If it is 0%, it is equal to the horsepower required for the engine to drive the hydraulic pump 1, so the engine consumes drive horsepower proportional to the cube of the engine rotation speed to drive the cooling fan 2b. This means that

[Problem to be solved by the invention] The above-mentioned conventional cooling fan drive device is as follows.

As mentioned above, this is a device for cooling the heat generated by the engine, which is absorbed by the water jacket of the engine when the engine is driven, in the radiator.

Therefore, when driving the engine, that is, when driving the vehicle, driving horsepower proportional to the cube of the engine rotation speed is consumed for cooling the cooling water in the radiator, which is explained above. Due to the configuration of the device, the engine drives the cooling fan 2b even during engine braking.

Therefore, even during engine braking, the driving horsepower of the cooling fan 2b is generated in proportion to the cube of the engine rotational speed, increasing the engine braking ability.However, due to the driving of this cooling fan, As mentioned above, the improvement in engine braking ability is proportional to the cube of the engine rotational speed, so unless the engine rotational speed is set considerably high, it will not be useful for improving the engine braking ability.

Conversely, during engine braking, if the engine rotational speed, that is, the rotational speed of the cooling fan 2b, continues to increase in order to set the engine brake to a large value, there is a risk that the radiator water temperature will become supercooled. be.

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

[Features for Solving the Problems] (1) Features of the invention according to claim 1 A hydraulic motor driven by pressure oil discharged from a hydraulic pump driven by an engine air-cools a radiator that cools cooling water of the engine. A conventional hydraulic drive in which a fan is driven and a pressure setting means is provided in the discharge line from the hydraulic pump is characterized in that the following cooling fan drive method is adopted.

That is, (a) during normal driving, the cooling fan is driven by the pressure oil discharged from the hydraulic pump as described above, and (b) during engine braking, the discharge pipe line between the pressure setting means and the hydraulic motor is driven. A method is adopted to increase the driving load of the engine by throttling the engine.

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

In this case, the set pressure of the pressure setting means may be set variable in conjunction with the engine brake operation.

(2) Features of the invention of claim 2 In addition to the invention of claim 1, when the engine brakes, the discharge pipe is throttled to increase the hydraulic pressure of the hydraulic pump discharge pipe, and the increased pressure oil is used. It is unique in that it drives another hydraulic motor linked to the generator.

That is, in claim 1, the hydraulic energy increased during engine braking is discarded from the pressure setting means, but in claim 2, the hydraulic energy is used to drive the generator by another hydraulic motor. The feature is that it recovers energy.

(3) Features of the invention according to claim 3 The pressure setting means according to claim 1 is a pressure setting means whose pressure setting is adjusted by the radiator water temperature, and when the engine is braked, the discharge pipe in claim 1 is closed. The feature is that at the same time as the radiator water temperature is reduced, the set pressure of the pressure setting means is increased regardless of the radiator water temperature. The pressure setting means is set to a low pressure to slow down or stop the rotational speed of the cooling fan 2b, but during engine braking, the pressure setting value of the pressure setting means is increased even if the radiator water temperature is low. This increases the engine braking ability.

[Example] Hereinafter, the present invention will be explained based on Examples.

FIG. 1 is a system diagram showing a cooling fan driving device necessary for carrying out the cooling fan driving method of the present invention, and a hydraulic pump 1 driven by an engine (not shown) is connected to a discharge pipe. 1b, a check valve 1a, a switching valve 3, and an inlet pipe 2d. The discharge pipe 2C communicates with the reservoir 7, and the discharge pipe 1b is provided with a first relief valve 4.
The pilot conduit 4b communicates with the reservoir 7 via the throttle channel 4C and the second relief valve 4a, and the pilot conduit 4b is connected to the reservoir 7 in parallel with the relief valve 4a as a bypass circuit. An off valve 6 is provided, and a chain valve 2a is provided in parallel with the hydraulic motor 2.

From the pipe IC connecting the check valve 1a and the switching valve 3,
It is connected to the hydraulic pump motor 5 via the check valve 5a and the inlet pipe 5C, and is connected to the discharge pipe 5d of the hydraulic pump motor 5.
communicates with the reservoir 7, a branch pipe line 3b from the switching valve 3 communicates with an inlet pipe line 5C of the hydraulic pump motor 5, and the hydraulic pump motor 5 is interlocked with the motor/generator 5b.

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

Under normal conditions, that is, when the water temperature in the engine water jacket is at an appropriate temperature and the vehicle is in a driving state, the solenoid 3a in the switching valve 3 is turned off, and the solenoid 3a in the on and off valve 6 is turned off. 6a is turned on, and the switching position of the switching valve 3 is such that the set pressure is the highest set pressure of the discharge pipe line 1b.

Here, the working oil pressure in the inlet pipe 2d is the cooling fan 2.
b, and the driving torque is proportional to the square of the rotational speed of the cooling fan 2b, as described above. Therefore, in this state, as in the conventional case, the hydraulic oil raised by the cooling fan 2b or the hydraulic pump l flows into the discharge pipe until the pressure reaches the set pressure set by the relief valve 4. 1b, the check valve 1a, the conduit IC1 switching position 3B, and the inlet conduit 2d. The discharged hydraulic oil returns to the reservoir 7 via the discharge pipe 2C.

In this case, the relief valve 4a sets the set pressure of the relief valve 4, and the pressure of the relief valve 4 is set.

Furthermore, the rotation of the cooling fan 2b driven in this manner generates an air stream in the radiator, and the air flow cools the water flowing into the radiator.

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

When the rotational speed of the engine is rapidly reduced from the driving state of the hydraulic pump l, the hydraulic motor 2 and the cooling fan 2b rotate due to the rotational inertia, so that
The pressure of the inlet pipe 2d tends to be lower than that of the discharge pipe 2C.

However, since the pressure in the inlet pipe 2d has become lower than the pressure in the discharge pipe 2C, the hydraulic oil in the discharge pipe 2C is replenished into the inlet pipe 2d via the check valve 2a, and the hydraulic motor 2 and the cooling The fan 2b performs a freewheel action, and the configuration of this freewheel action is well known.In contrast to the normal state described above, when the radiator water temperature is still low, the cooling fan 2b is driven to provide cooling air to the radiator. Therefore, when the radiator water temperature is still low, the solenoid 6a
is turned off, and the on/off valve 6 is opened.

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

As a result, in this state, the discharge pipe line 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, the solenoid 6a turns on, and the on-off valve 6
is in the closed state, and the set pressure of the relief valve 4 is high.
It has become.

In this state, when the engine accelerator pedal is returned to zero or by 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 force-fed from the branch pipe 3b to the inlet pipe 5C via the discharge pipe 1b, the chain valve 1a pipe 1c, and the switching position 3A, and the hydraulic oil is The pump motor 5 is driven, the motor generator 5b is driven as a generator, and the electric power generated by the motor/generator 5b is charged into a battery (not shown).

When the hydraulic motor 2 is stopped, the rotational inertia of the hydraulic motor 2 causes a sudden negative pressure in the inlet pipe 2d.

Also, in this case, as mentioned above, the presence of the check valve 2a causes the hydraulic motor 2 to perform a freewheel action. It is converted and recovered by the battery, and the driving load portion improves the engine braking ability of the engine.

In addition, in this case, the switching position 3 in the switching valve 3
In A, there is a restriction in the passage communicating from the conduit 1c to the inlet conduit 2d.

This means the following.

If the cooling fan 2b has been driven at a relatively high speed until now, if the engine brake suddenly occurs, the pressure oil supply to the inlet pipe 2d becomes too complete, and its freewheeling effect becomes insufficient. There is a fear.

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

In the case where engine braking is required, even if the radiator water temperature is too low as described above, the on/off valve 6 gives priority to engine braking,
In this case, the solenoid 6a is turned on and the set pressure of the relief valve 4 is set to a normal high set pressure, so that the engine brake is applied.

Furthermore, the energy charged in the battery is reused as described below when the vehicle accelerates.

When the automobile accelerates, the switching valve 3 is set to the switching position 3B, and the on/off valve 6 is opened using the setting force to control the motor.
Drive the generator 5b.

As a result, the set pressure of the relief valve 4, that is, the set pressure of the discharge pipe ib becomes the same atmospheric pressure as the zarpa 7,
The hydraulic pump motor 5 performs a pumping action by driving the motor/generator 5b, and the hydraulic pump motor 5 drains the hydraulic oil from the reservoir 7 from the discharge pipe 5d to the inlet pipe 5C.
The discharged pressure oil pushes open the check valve 5a, and further drives the hydraulic motor 2 via the pipe line 1c, the switching position 3B and the inlet pipe line 2d, which causes the cooling fan 2b to operate as described above. Similarly, cooling air will be sent to the radiator.

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

By the operation described in 1, the cooling fan 2b is driven without using energy from the engine, that is, with no load on the hydraulic pump l, the cooling fan 2b is driven by the electric energy of the battery.
Therefore, when the car accelerates, there is a margin in the engine's output since the cooling fan 2b was previously driven by the engine, and with that margin,
This means that the engine can effectively accelerate the car.

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 a pressure setting means for setting the set pressure in the discharge pipe line 1b. This is to select and set the maximum pressure in the discharge pipe 1b to either a predetermined allowable maximum pressure or atmospheric pressure.

However, this pressure setting means may be, for example, a relief valve.
The set pressure may be constant, as in

However, if the pressure setting means can be adjusted stepwise or in an analog manner, the pressure generated in the hydraulic pump l can be adjusted continuously during engine braking as described above, even if the engine rotational speed is the same. It is advantageous to be able to control the engine braking capacity by varying the engine speed.

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

However, conventionally, during engine braking when radiator cooling is not necessary, the cooling fan 2b is driven and its driving energy is consumed without recovering the energy.

According to the present invention, the conduit IC is throttled during engine braking to apply engine braking more than before even when the engine rotational speed is low. Therefore, from the sole purpose of improving engine braking performance, the above energy recovery is not necessarily necessary.In addition, engine braking energy may be converted into electrical energy and recovered, and the recovered energy may be reused when the vehicle accelerates. However, this electrical energy is not necessarily reused for accelerating the vehicle, but may be used for other power uses.

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

(1) Regarding the invention of claim 1, in a hydraulic drive device for a cooling fan, by throttling the discharge pipe of the hydraulic pump l, the load resistance in the engine is increased regardless of the engine rotation speed, and thereby the engine It becomes possible to improve the braking ability.

(2) Regarding the invention of claim 2, in addition to the effect of claim 1, converting and recovering the high hydraulic energy generated by throttling the discharge pipe of the hydraulic pump l in claim 1 into electrical energy is As for the recovered brake energy, it is possible to use it effectively.

(3) Regarding the invention of claim 3, the pressure setting means provided in the discharge pipe of the hydraulic pump l according to claim 1 is configured such that its setting value can be set to atmospheric pressure when the radiator water temperature is low, and the radiator Cooling fan 2 when water temperature is low
By stopping the rotation of b, it becomes possible to effectively increase the radiator water temperature.

In the case of claim Xjj3, the set pressure of the pressure setting means can be increased during engine braking. This makes it possible to increase the set pressure of the engine, thereby improving its engine braking ability.

[Brief explanation of the drawing]

Fig. 1 shows a system diagram of a hydraulic drive device for a cooling fan necessary to implement the cooling fan drive method of the present invention, and Fig. 2 shows a system diagram of a hydraulic drive device for a cooling fan in the prior art. This is shown in the figure. The main symbols used in the examples are as follows. l: Hydraulic pump, lb = discharge pipe, 2: Hydraulic motor, 2b: Cooling fan, 3: Switching valves 4 and 4a: Relief valve: Hydraulic pump motor, 5b: Motor generator

Claims (1)

[Claims] 1. A hydraulic motor driven by pressure oil discharged from a hydraulic pump driven by the engine drives an air cooling fan of a radiator that cools cooling water of the engine, and In a hydraulic drive in which a pressure setting means is provided in a conduit, during engine braking, the discharge conduit between the pressure setting means and the hydraulic motor is throttled to increase the driving load of the engine, and during normal running, the discharge conduit is reduced. A method for driving a cooling fan, characterized in that the constriction of the conduit is opened and the cooling fan is driven by pressure oil discharged from the hydraulic pump. 2. The cooling fan driving method according to claim 1, wherein during engine braking, another hydraulic motor linked to the generator is driven by pressure oil generated between the hydraulic pump and the pressure setting means. 3. A hydraulic motor driven by pressure oil discharged from a hydraulic pump driven by the engine drives an air cooling fan of a radiator that cools the cooling water of the engine, and the radiator water temperature is sent to the discharge pipe from the hydraulic pump. In a hydraulic drive equipped with a pressure setting means for adjusting the pressure setting, when the engine brakes, the discharge pipe line between the pressure setting means and the hydraulic motor is throttled and the set pressure of the pressure setting means is adjusted. Also increase the
Driving a cooling fan characterized in that the drive load of the engine is increased, the throttle of the discharge pipe is opened during normal running, and the cooling fan is driven by the pressure oil discharged from the hydraulic pump. Method.