JP2004090776A - Control device of cooling fan for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize the total of the drive load of a compressor and the load in operating a cooling fan when an air-conditioner is operated. <P>SOLUTION: An alternator 2 is driven by an engine 1 to generate power. When an air-conditioner 3 is operated, a compressor 8 is driven by the engine 1. An electric cooling fan 4 is operated by the supply of the power generated by the alternator 2 to cool a condenser 9. A control unit (C/U) 5 sets the target compressor discharge pressure so that the total of the drive load of the compressor and the drive load of the alternator 2 to obtain the working power of the electric cooling fan 4 is minimized to the required cooling capacity of the air-conditioner 3, and controls the operation of the electric cooling fan 4 so that the compressor discharge pressure detected by a discharge pressure sensor 23 is the target compressor discharge pressure. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a vehicle cooling fan, and more particularly to a technique for controlling an engine load to a minimum during operation of an air conditioner.
[0002]
[Prior art]
A control device for a vehicle cooling fan is disclosed in Japanese Patent Application Laid-Open No. 2000-274243. This device sets the control constants of the cooling fan with reference to an operation map using vehicle speed, engine cooling water temperature, compressor discharge rate and engine speed as parameters, thereby minimizing the operation of the cooling fan and saving power. It is trying to make it.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, a map of a different control constant is selected using a driving state that constantly fluctuates during traveling, such as a vehicle speed and an engine rotation speed, as a parameter. When the switching threshold value is exceeded, the control constant changes, and there is a problem that stable fan operation characteristics (state) cannot be obtained due to hunting. In addition, since a plurality of maps are provided, there is a problem that a memory capacity increases.
[0004]
Further, when the air conditioner is operated, the cooling fan is operated to cool the condenser of the air conditioner. However, in the above-described conventional apparatus, the load due to the operation of the air conditioner (drive load of the compressor) and the operation of the cooling fan are reduced. And the total load of the air conditioner is not minimized, that is, it is not possible to control the air conditioner to an optimum point that ensures both the required cooling capacity (required cooling capacity) and the power saving. There was room for further improvement from the viewpoint of energy saving.
[0005]
The present invention has been made in order to solve such a problem, and a vehicle cooling fan control device that satisfies a required cooling capacity with minimum driving energy and that can obtain stable fan operating characteristics. The purpose is to provide.
[0006]
[Means for Solving the Problems]
For this reason, the control device for a vehicle cooling fan according to the present invention sums up the driving load of the compressor of the air conditioner and the driving load of the generator for obtaining the operating power of the electric cooling fan for cooling the air conditioner. The target discharge pressure of the compressor is set so as to minimize the applied load, and the operation of the electric cooling fan is controlled so that the discharge pressure of the compressor becomes the target discharge pressure.
[0007]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the control apparatus of the cooling fan for vehicles which concerns on this invention, the load with respect to the engine accompanying the driving | operation of an air conditioner can be minimized, ensuring the required cooling capacity at the time of operation of an air conditioner. Can be improved. Further, since the set target discharge pressure changes continuously with the change in the required cooling capacity of the air conditioner, stable fan operation characteristics can be secured.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall system configuration diagram of a cooling fan control device according to an embodiment of the present invention. As shown in FIG. 1, the cooling fan control device includes an engine 1, an alternator 2, an air conditioner (air conditioner) 3, an electric cooling fan 4, and a control unit (C / U) 5. Is done.
[0009]
The heat generated by the engine 1 is absorbed by engine cooling water passing through the water jacket, and the absorbed heat is released via a radiator (not shown).
The alternator 2 is mechanically connected to the output shaft of the engine 1 and is driven by the power of the engine 1 to generate power. The alternator 2, the electric cooling fan 4, and the battery 6 are electrically connected via a regulator 7. Then, the electric power generated by the alternator 2 is supplied to the electric cooling fan 4 via the regulator 7 so that the electric cooling fan 4 operates.
[0010]
The air conditioner 3 is mechanically connected to an output shaft of the engine 1 and is driven by the power of the engine 1 to suck in, compress, and discharge the refrigerant at a high temperature and a high pressure, and a refrigerant discharged from the compressor 8. A condenser 9 for cooling and liquefying the refrigerant, a receiver dryer 10 for temporarily storing the refrigerant liquefied by the condenser 9, an expansion valve 11 for vaporizing and liquefying the liquefied refrigerant and injecting the same. And an evaporator 12 cooled by passage of the refrigerant, and these are connected by a refrigerant pipe 13. Then, cool air is generated by passing air through the evaporator 12 by the blower fan 14. An electromagnetic clutch (not shown) is connected to the compressor 8 so that power from the engine 1 can be transmitted or cut off.
[0011]
The electric cooling fan 4 operates by receiving power supply, and sends cooling air (for heat exchange) to the radiator and the condenser 9. Thus, the engine performance is maintained while avoiding overheating, and the heat radiation performance of the condenser 9 is enhanced to maintain the air conditioner performance.
The control unit (C / U) 5 includes a water temperature sensor 21 for detecting an engine coolant temperature, an outside air temperature sensor 22 for detecting an outside air temperature, and a discharge pressure sensor for detecting a refrigerant pressure (discharge pressure) discharged from the compressor 8. 23, detection signals from various detection sensors such as a post-evaporation temperature sensor 24 for detecting the temperature of the cool air passing through the evaporator 12 (post-evaporation temperature), a current sensor 25 for detecting a current from the alternator 2, and an air conditioner switch. Signals from 26 (ON / OFF, required cooling capacity) are input.
[0012]
Then, the control unit (C / U) 5 performs predetermined arithmetic processing based on detection signals input from various detection sensors, and executes engine control such as fuel injection control. In addition, the electromagnetic clutch is engaged / disengaged in accordance with the outside air temperature, the blow-out temperature after evacuating, etc., and the compressor 8 is driven and stopped (control of the air conditioner 3) so as to obtain the required cooling capacity from the air conditioner switch 26. I do.
[0013]
Further, the control unit (C / U) 5 variably controls the electric cooling fan 4 via the fan drive unit 27 according to the operating state of the air conditioner 3 and the outside air temperature. Here, in this embodiment, the control of the electric cooling fan executed by the control unit (C / U) 5 will be described in detail.
In the control, first, when the air conditioner 3 is operating, the target discharge pressure of the compressor 8 is set, and the operation duty of the electric cooling fan 4 (hereinafter, referred to as “discharge pressure”) is set such that the discharge pressure maintains the target discharge pressure. Operating duty "). The target discharge pressure set here is the minimum load (total load) of the driving load of the compressor 8 for the required cooling capacity and the driving load of the electric cooling fan 4 for cooling the condenser 9. And specifically set as described below.
[0014]
That is, since the compressor 8 is driven by the output of the engine 1, the power for driving the compressor 8 (compressor power) is the load on the engine 1 itself. Since the compressor power can be expressed as “discharge pressure−suction pressure (constant)”, the compressor discharge pressure (compressor power) can be converted to the driving load of the compressor 8.
[0015]
The electric cooling fan 4 is operated by the electric power from the alternator 2, and the alternator 2 is driven by the output of the engine 1 to generate electric power. The power for driving the alternator 2, that is, the load on the engine 1, can be determined from the integrated value of the electric current generated by the alternator 2. Can be converted to the driving load.
[0016]
On the other hand, when the condenser 9 of the air conditioner 3 is cooled by the electric cooling fan 4, the condensing temperature of the refrigerant in the condenser 9 and consequently, the condensing pressure decreases. As a result, the discharge pressure of the compressor 8 decreases, and the driving load of the compressor 8 also decreases.
From the above, when the operation duty (fan operation duty) of the electric cooling fan 4 is changed with respect to the required cooling capacity of the air conditioner 3 to increase the air volume, that is, the effect of cooling the condenser 9, The drive load (discharge pressure) of the compressor 8 decreases, and the drive load of the alternator 2 (power consumption of the electric cooling fan 4) increases. Therefore, by changing the fan operation duty, it is possible to find an operation point (optimum point) at which the sum of the drive load of the compressor and the drive load of the alternator (that is, the operation load of the electric cooling fan) is minimized. . By operating the fan at this optimum point, that is, by controlling the fan operation duty so as to maintain (maintain) the compressor discharge pressure (target discharge pressure) at this time, the engine load associated with the operation of the air conditioner 3 can be improved. Can be suppressed to a minimum, and as a result, fuel efficiency can be improved.
[0017]
FIG. 2 shows the above relationship and the optimum point. FIGS. 2A to 2C show the cases where the outside air temperature is low, medium, and high, respectively. In FIG. 2, a broken line indicates a driving load of the compressor 8, a dashed line indicates a driving load of the alternator 2 for operating the electric cooling fan 4, and a solid line indicates a total load of these. Then, a target discharge pressure map is created by obtaining the optimum point for each outside temperature and arranging the optimum compressor discharge pressure with respect to the outside temperature (FIG. 3). Set the pressure.
[0018]
Therefore, when the discharge pressure detected by the discharge pressure sensor 23 is higher than the target discharge pressure, the “operation duty by discharge pressure” is set in a direction to increase the current operation duty, and the target discharge When the pressure is lower than the pressure, the “operation duty based on the discharge pressure” is set in a direction to decrease the current operation duty. FIG. 4 shows an example of the behavior of the fan operation duty and the compressor discharge pressure during the operation of the air conditioner 3.
[0019]
Next, an operation duty of the electric cooling fan 4 (hereinafter, referred to as “operation duty based on water temperature”) is set so that the engine cooling water temperature maintains the target engine cooling water temperature. The target engine coolant temperature is set in advance according to the vehicle and engine characteristics and stored.
Therefore, as shown in FIG. 5, when the engine coolant temperature detected by the coolant temperature sensor 21 is higher than the target engine coolant temperature, the “operation duty based on water temperature” increases the current operation duty. If the temperature is lower than the target engine coolant temperature, the "operation duty based on water temperature" is set in a direction to decrease the current operation duty. FIG. 5 shows an example of the behavior of the fan operation duty and the engine coolant temperature when the air conditioner 3 is stopped.
[0020]
Then, by comparing the “drive duty by the discharge pressure” with the “operation duty by the water temperature”, the higher of the required value is set as the final operation duty, which is output to the electric cooling fan 4 to be operated. When the air conditioner 4 is stopped, the “operation duty based on water temperature” is set as a final operation duty.
[0021]
FIGS. 6 and 7 are flowcharts of the electric cooling fan control described above, which are executed at predetermined time intervals. In FIG. 6, in step 1 (referred to as S1 in the figure, the same applies hereinafter), the state of the air conditioner switch 27 is read.
In step 2, it is determined whether the air conditioner 3 is operating (ON) or stopped (OFF). If the air conditioner 3 is operating, the process proceeds to step 3.
[0022]
In step 3, the engine coolant temperature is read from the water temperature sensor 21, the outside air temperature from the outside air temperature sensor 22, and the discharge pressure from the discharge pressure sensor 23. In steps 4 to 8, "operation duty by discharge pressure" is set, and in steps 9 to 13, "operation duty by water temperature" is set.
In step 4, it is determined whether or not the read discharge pressure exceeds a predetermined pressure Pu. This determination is made, for example, to protect the compressor 8, and the upper limit discharge pressure from such a viewpoint is set as the predetermined pressure. If the discharge pressure is higher than the predetermined pressure Pu, the process proceeds to step 5, where the maximum value (duty 100%) is set as the emergency “operation duty by discharge pressure” and the process proceeds to step 14. As a result, the electric cooling fan 4 cools the air conditioner 3 (condenser 9) with the maximum air volume (maximum cooling effect is obtained). On the other hand, if the discharge pressure is equal to or lower than the predetermined pressure Pu, the process proceeds to step 6.
[0023]
In step 6, the target discharge pressure is set according to the outside temperature with reference to a map as shown in FIG.
In step 7, the read discharge pressure is compared with the set target discharge pressure. If the discharge pressure is different from the target discharge pressure, the process proceeds to step 7, and if the discharge pressure matches the target discharge pressure, the process directly proceeds to step 14.
[0024]
In step 8, the "operation duty based on the discharge pressure" at the normal time is set. More specifically, if the discharge pressure> target discharge pressure read, a predetermined duty to the current operating duty (e.g., a _1%) plus, if the discharge amount <target discharge pressure read, the current operation A predetermined duty (for example, b ₁ %) is subtracted from the duty.
[0025]
In step 9, it is determined whether or not the read engine coolant temperature is higher than a predetermined temperature Tu. This determination is made, for example, in order to avoid overheating and maintain engine performance, and an upper limit temperature from such a viewpoint is set as the predetermined temperature. If the engine coolant temperature is higher than the predetermined temperature Tu, the process proceeds to step 10, where the emergency operation duty based on the water temperature is set to the maximum value (duty 100%), and the process proceeds to step 14. As a result, the electric cooling fan 4 cools (the radiator of) the engine 1 with the maximum air volume (a maximum cooling effect is obtained). On the other hand, if the engine cooling water temperature is equal to or lower than the predetermined temperature Tu, the routine proceeds to step 11.
[0026]
In step 11, the stored target engine coolant temperature is read.
In step 12, the read engine coolant temperature is compared with the target engine coolant temperature. If the engine coolant temperature is different from the target coolant temperature, the process proceeds to step 13, and if the engine refrigerating water temperature and the target engine coolant temperature match, the process directly proceeds to step.
[0027]
In step 13, the normal "operation duty based on water temperature" is set. Specifically, if the read engine cooling water temperature> the target engine cooling water temperature, a predetermined duty (for example, a ₂ %) is added to the current operation duty, and the read engine cooling water temperature <the target engine cooling water If it is a temperature, a predetermined duty (for example, b ₂ %) is subtracted from the current operation duty.
[0028]
In step 14, the "operation duty based on the discharge pressure" and the "operation duty based on the water temperature" are compared, and the larger one is selected as the operation duty of the electric cooling fan 4.
On the other hand, if the air conditioner 3 is stopped in step 2, the process proceeds to step 15 in FIG. Then, in steps 16 to 20, "operation duty based on water temperature" is set as in steps 9 to 13, and this is set as the operation duty of the electric cooling fan.
[0029]
The compressor 8 of this embodiment is of an ON / OFF type that switches between driving and stopping, but may be of a type that can also change the discharge capacity.
The embodiment described above has the following effects.
(1) For example, when the temperature around the vehicle (for example, the outside air temperature) rises, the heat load on the evaporator 12 and the heat radiation capacity of the condenser 9 decrease, so that the load on the compressor also increases. In this regard, in the above-described embodiment, since the target discharge amount is set according to the outside air temperature, it is possible to set the target discharge pressure accurately corresponding to the driving load of the compressor 8 that fluctuates depending on the ambient temperature.
(2) The electric cooling fan 4 is controlled by one of the “operation duty by the discharge pressure” and the “operation duty by the water temperature”, that is, according to the compressor discharge pressure or the engine cooling water temperature whose change speed is relatively slow. Therefore, the fan operation characteristics (state) are stabilized.
(3) During the operation of the air conditioner, the “operating duty by the discharge pressure” and the “operating duty by the water temperature” are compared to control the electric cooling fan 4 with a higher required value. It can be operated to secure the required air volume.
(4) When the compressor discharge pressure detected by the discharge pressure sensor 23 exceeds the predetermined pressure Pu during the operation of the air conditioner, the electric cooling fan 4 is operated at its maximum control amount (operation duty 100%). The maximum fan cooling effect can be ensured, and the compressor 8 can be protected from an abnormal rise in the discharge pressure (the load on the compressor 8 can be prevented and the performance can be prevented from deteriorating).
(5) When the engine cooling water temperature detected by the water temperature sensor 21 is higher than the predetermined temperature Tu, the electric cooling fan 4 is operated at its maximum control amount (operation duty 100%), so that the maximum fan cooling effect is obtained. , The engine temperature can be prevented from rising excessively (overheating can be avoided).
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a control device for a vehicle cooling fan according to an embodiment of the present invention.
FIG. 2 is a diagram showing a driving load of a compressor (discharge pressure) and a driving load of an alternator (electric cooling fan power consumption) with respect to a fan operation duty.
FIG. 3 is a diagram showing an example of a target discharge pressure map.
FIG. 4 is a diagram illustrating behaviors of a fan operation duty and a compressor discharge pressure during operation of an air conditioner.
FIG. 5 is a diagram illustrating behaviors of a fan operation duty and an engine coolant temperature when the air conditioner is stopped.
FIG. 6 is a flowchart showing control contents of the electric cooling fan when the air conditioner is turned on.
FIG. 7 is a flowchart showing control contents of the electric cooling fan when the air conditioner is turned off.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 engine, 2 alternator (generator), 3 air conditioner (air conditioner), 4 electric cooling fan, 5 control unit C / U (target discharge pressure setting means, cooling fan control means), 8 compressor 9: condenser, 12: evaporator, 21: water temperature sensor, 22: outside temperature sensor, 23: discharge pressure sensor, 24: post-evaporation temperature sensor, 25: current sensor

Claims (6)

Engine and
A generator driven by the engine;
An air conditioner whose compressor is driven by the engine;
An electric cooling fan that operates upon receiving the power generated by the generator and cools the air conditioner,
Discharge pressure detecting means for detecting a discharge pressure of the compressor,
The compressor so that the sum of the drive load of the compressor and the drive load of the generator for obtaining the operating power of the electric cooling fan is minimized with respect to the required cooling capacity of the air conditioner. Target discharge pressure setting means for setting a target discharge pressure of
Cooling fan control means for controlling the operation of the electric cooling fan so that the discharge pressure of the compressor becomes the target discharge pressure,
A control device for a vehicle cooling fan, comprising: 2. The control device according to claim 1, wherein the target discharge pressure is set according to a representative temperature around the vehicle. It has an outside air temperature detecting means for detecting the outside air temperature,
The control device for a vehicle cooling fan according to claim 2, wherein the representative temperature is an outside air temperature detected by the outside air temperature detecting means. The electric cooling fan cools both the engine and the air conditioner,
The cooling fan control means, a control amount to set the discharge pressure of the compressor to be the target discharge pressure, a control amount to set the engine coolant temperature to a preset target engine coolant temperature, The control device for a vehicle cooling fan according to any one of claims 1 to 3, wherein the larger one of the electric cooling fans is operated. 5. The cooling fan control means according to claim 1, wherein when the discharge pressure of the compressor exceeds a predetermined value, the cooling fan control means operates the electric cooling fan with the maximum control amount. 4. The control device for a vehicle cooling fan according to any one of claims 1 to 3. 6. The vehicle cooling system according to claim 4, wherein the cooling fan control means activates the electric cooling fan with the maximum control amount when the engine cooling water temperature exceeds a predetermined temperature. Fan control device.

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