JPH05238252A - Air conditioner for automobile - Google Patents

Abstract

PURPOSE:To improve fuel consumption, maintain the comfortable drivability of an air conditioner for automobile equipped with an EPR in the refrigeration cycle. CONSTITUTION:As for an air conditioner 1 equipped with an EPR 16 in a refrigeration cycle 10, a compressor 11 is intermittently controlled by an air conditioner 20, on the basis of the detection temperature of a temperature sensor 25 installed on the downstream side of an evaporator 15 in an air conditioner duct 2, and when the traveling speed of an automobile becomes less than a prescribed speed or the engine revolution speed becomes less than a prescribed revolution speed, an electromagnetic clutch 17 is turned ON, and the compressor 11 is necessarily driven. On stop, the drive of the compressor 11 is not started, and since the number of idling revolution does not vary, comfortability is not deteriorated, and fuel consumption is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner equipped with a pressure adjusting valve or the like for adjusting the pressure of refrigerant in an evaporator of a refrigeration cycle to a certain pressure or more.

[0002]

2. Description of the Related Art In an automobile air conditioner, an EPR (evaporator pressure regulator) having a valve for adjusting pressure is provided on the outlet side of the evaporator in order to prevent freezing (frost) of an evaporator (evaporator) in a refrigeration cycle. Then, there is a method in which the evaporation pressure of the refrigerant in the evaporator is set to a certain pressure or higher. With this type of EPR, when the air conditioner is operating, the electromagnetic clutch for transmitting engine power to the refrigerant compressor is always energized, and the electromagnetic clutch is not repeatedly interrupted, so that the refrigerant compressor operates. Because the refrigerant continues to circulate and the EPR pressure adjustment keeps the evaporator temperature from dropping too low, there is no temperature fluctuation associated with stopping the refrigerant compressor during operation of the air conditioner, especially when the vehicle is stopped, A comfortable air conditioning operation is possible because the driver does not feel uncomfortable such as a change in the idling speed of the engine due to the on / off of the electromagnetic clutch.

[0003]

However, the above-mentioned EPR
In the case of using the compressor, the compressor is operated even when the cooling load of the evaporator is small, and the evaporation pressure of the refrigerant in the evaporator is raised to a certain pressure or higher by the EPR. Refrigerant pressure decreases and the compression ratio increases, thus reducing the efficiency of the compressor. Therefore, the EPR system has a problem that the fuel efficiency of the vehicle is poorer than that of the system in which the electromagnetic clutch is discontinued to control the operation rate of the compressor according to the cooling load.

An object of the present invention is to improve the fuel efficiency of an engine in an air conditioner provided with an EPR in a refrigeration cycle while maintaining the comfortable operability peculiar to the air conditioner provided with the EPR as much as possible.

[0005]

The present invention is directed to a compressor driven by an engine via an electromagnetic clutch, an evaporator in a refrigeration cycle in which a refrigerant is circulated by the compressor, and an inside of the evaporator in the refrigeration cycle. A pressure adjusting valve for adjusting the evaporation pressure of the refrigerant to a certain pressure or more, a heater core for circulating the cooling water of the engine, an air-conditioning duct that blows air into the vehicle compartment by sequentially disposing the evaporator and the heater core, Temperature adjusting means for adjusting the amount of air heated by the heater core, a cooling state sensor for detecting a physical quantity related to the cooling degree of the evaporator in the air conditioning duct, and the electromagnetic clutch based on a detection signal of the cooling state sensor. Compressor on / off control means for controlling the on / off of the compressor to control the drive of the compressor, and the running state of the vehicle or the engine Detecting means for detecting at least one of the number of revolutions, and energizing the electromagnetic clutch when the detecting means detects at least one of a state where the vehicle traveling speed is equal to or lower than a predetermined speed or an engine speed is equal to or lower than a predetermined rotation number Then, a technical means including a compressor forced drive means for forcibly driving the compressor is adopted.

[0006]

In the present invention, the cooling degree sensor detects the cooling degree of the evaporator in the air conditioning duct, and the electromagnetic clutch is disengaged according to the detection signal, so that the compressor is driven according to the cooling load. .. On the other hand, when it is detected that the traveling speed is equal to or lower than the predetermined speed or the engine speed is equal to or lower than the predetermined speed, the electromagnetic clutch is forcibly energized to drive the compressor.
Therefore, the compressor can always be operated before the vehicle stops. Even if the cooling load decreases and the evaporator temperature decreases when the compressor is operating, the pressure of the refrigerant in the evaporator is adjusted by the pressure adjustment valve, so the evaporator temperature falls below the freezing temperature. Never fall too low,
This can prevent freezing of the evaporator.

[0007]

According to the present invention, when the air-conditioning duct has a small cooling load while the vehicle is running, the compressor is intermittently controlled by the electromagnetic clutch, so that the pressure control valve (for example, E
The load on the engine is smaller than that using only PR and the fuel consumption in the engine is reduced. At this time, the temperature of the air passing through the evaporator fluctuates due to the on / off of the electromagnetic clutch, but the temperature fluctuation is alleviated when the outlet temperature is controlled by the heater core downstream of the evaporator, and the user does not feel uncomfortable. No loss of comfort. Also, if the traveling speed decreases to below the predetermined speed or the engine speed falls below the predetermined speed, the compressor is restarted before the car stops, so the car stops. The compressor is not driven after it has stopped, and the idle speed of the engine does not suddenly change while the vehicle is stopped. Therefore, the occupant does not feel uncomfortable due to fluctuations in the idle speed.

[0008]

EXAMPLES Next, the present invention will be explained based on examples. An air conditioner 1 for an automobile shown in FIG. 1 is provided with a blower 3 upstream of an air conditioning duct 2, and a refrigeration cycle 10 includes a compressor 11, a condenser (condenser) 12, a receiver 13, an expansion valve 14, and an evaporator ( An evaporator 15 and an EPR (evaporator pressure regulator) 16 are sequentially connected by a refrigerant pipe to arrange the evaporator 15 in the air conditioning duct 2 and to evaporate the heater core 4 which is connected to the engine water jacket in a circulation path. It is arranged in the air conditioning duct 2 on the downstream side of the container 15. An air mix damper 5 for adjusting the amount of air cooled by the evaporator 15 and passing through the heater core 4 is provided on the upstream side of the heater core 4 in the air conditioning duct 2, and on the downstream side of the air conditioning duct 2. Is connected to a blower duct 6 having outlets at various places inside the vehicle, and the outlets are switched by an outlet switching damper (not shown). Reference numeral 7 denotes an inside / outside air switching damper that switches the intake of air into the air conditioning duct 2 between the inside air and the outside air. The air mix damper 5 includes a driving servo motor (not shown) and a potentiometer (for detecting the opening). (Not shown).

In the refrigeration cycle 10, the compressor 11
Is connected to the engine via the electromagnetic clutch 17, and the torque of the engine is transmitted when the electromagnetic clutch 17 is energized to circulate the refrigerant in the refrigeration cycle 10. E
The PR 16 is a pressure adjusting valve that adjusts the throttle amount of the refrigerant passage on the outlet side of the evaporator 15, and keeps the evaporation pressure of the refrigerant in the evaporator 15 at a certain pressure or more, so that the evaporator when the cooling load is low. Prevents the temperature drop of 15 and prevents freezing (frost). Here, the temperature of the evaporator 15 is 0 to −
Evaporation pressure (about 1.9 kg / c)
m2) is set in EPR16. The vehicle air conditioner 1 having the above configuration is controlled by the air conditioner control device 20 mainly composed of a microcomputer.

The automatic operation of the air conditioner controller 20 will be described below. The air conditioner control device 20 is a temperature setting device 2 provided on a control panel provided in the vehicle compartment.
According to the set temperature of 1, the blower 3 automatically controls the amount of air blown, the temperature of air blown into the passenger compartment, and the like. Here, a target outlet temperature To of the air blown from the air conditioning duct 2 into the vehicle interior is determined, the applied voltage to the blower 3 is controlled according to the target outlet temperature To, and the target outlet temperature To is controlled. The opening degree of the air mix damper 5 is controlled. In the present embodiment, the state in which the air mix damper 5 is closed refers to a case where the air passing through the air conditioning duct 2 does not pass through the heater core 4, that is, the maximum cooling state (max cool), The larger the opening of the air mix damper 5, the more air passes through the heater core 4. The target outlet temperature To is the temperature setter 21.
It is repeatedly determined by the following equation at every predetermined sampling time, based on the set temperature Tset according to, the detection information from the inside air temperature sensor 22, the solar radiation sensor 23, and the outside air temperature sensor 24.

[0011]

## EQU1 ## To = Kset * Tset-Kr * Tr-Kam * T
am-Ks x Ts + C

Here, Tr is the inside air temperature detected by the inside air temperature sensor 22, Ts is the amount of solar radiation detected by the solar radiation sensor 23, Tam is the outside air temperature detected by the outside air temperature sensor 24, and Kset, Kr, K
s and Kam are coefficients, and C is a constant.

In controlling the blower 3, the target outlet temperature To
Accordingly, the air volume is controlled by changing the supply voltage to the blower motor that drives the blower 3 so that the air volume becomes larger as the vehicle interior needs to be cooled or heated more rapidly. .. In the control of the air mix damper 5, the detection temperature T of the temperature sensor 25 provided for detecting the air temperature downstream of the evaporator 15, the detection temperature of the water temperature sensor provided in the water jacket of the engine, and the target The servomotor is energized to move the air mix damper 5 so that the opening degree is determined by the blowout temperature To. In addition, opening / closing control of a water valve provided between the water jacket of the engine and the heater core 4 is performed as necessary. With the above-described configuration, in the automobile air conditioner 1, when air is blown by the operation of the blower 3, after the air is cooled by the evaporator 15, the reheat amount by the heater core 4 is changed by the opening degree of the air mix damper 5. Is adjusted to control the vehicle interior temperature.

On the other hand, in the refrigeration cycle 10, EP
Since R16 is provided and the evaporation pressure of the refrigerant in the evaporator 15 is adjusted to a certain pressure or higher according to the cooling load of the evaporator 15, it is not necessary to stop the compressor 11 during the operation of the air conditioner. Although it is possible to prevent icing, in the present embodiment, in order to improve fuel efficiency, compressor intermittent control for intermittently driving the compressor 11 based on the detected temperature T of the temperature sensor 25 downstream of the evaporator 15 is performed. To do.

This on / off control of the compressor is performed by the electromagnetic clutch 17 when the temperature T detected by the temperature sensor 25 exceeds 4 ° C.
When the detected temperature T becomes 3 ° C. or less, the electromagnetic clutch 17 is stopped from being energized.
In order to prevent the comfort of the refrigeration cycle 10 in which the temperature sensor 6 is provided from being impaired, the compressor 11 is not controlled solely based on the temperature T detected by the temperature sensor 25, but the traveling speed of the vehicle is set to a predetermined value. The condition is satisfied, the air mix damper 5 is opened, and the compressor 11 is stopped only when reheating by the heater core 4 is performed. Therefore, the air conditioner control device 20 includes the engine control device 30 that controls the engine of the automobile.
From, vehicle speed and other control signals are transmitted.

A first embodiment of the compressor intermittent control will be described below with reference to FIG. When the air conditioner switch is turned on (YES in step S1),
It is determined whether or not the vehicle speed exceeds a predetermined speed (for example, 10 km / h), and if the vehicle speed is equal to or lower than the predetermined speed (step S
2), the electromagnetic clutch 17 is energized to forcibly drive the compressor 11 (step S3).

If the vehicle speed exceeds the predetermined speed (NO in step S2), it is determined whether or not the vehicle speed is decelerating. Here, as a means for determining whether or not the vehicle speed is decelerating, it is possible to detect it by directly detecting a change in the vehicle speed, and an ON signal of the brake switch indicating that the brake pedal is depressed. Alternatively, an accelerator switch off signal indicating that the accelerator pedal has been released can be used.

If the vehicle speed is decelerating (step S
4), the process proceeds to step S3 regardless of the vehicle speed, and the compressor 11 is forcibly driven. As a result, even if the vehicle is decelerated rapidly so that it cannot be detected in time below the predetermined speed, the electromagnetic clutch 17 is surely energized before the vehicle stops, and the compressor 1
1 can be driven. When the deceleration of the vehicle speed is not detected (NO in step S4), it is further determined whether or not the air mix damper 5 is closed, the air mix damper 5 is closed, and the air passing through the evaporator 15 is heated by the heater core. If it is in the maximum cooling state (max cool) that does not pass 4 (YE in step S5)
S), reheating by the heater core 4 is not performed, and the evaporator 1
Because the air cooled in 5 is blown out into the vehicle interior as it is,
This is a case where when the compressor 11 stops and the cooling capacity of the evaporator 15 decreases, the temperature of the blown-out air rises and the passengers immediately notice. Therefore, in this case, step S3
Then, the electromagnetic clutch 17 is energized to put the compressor 11 in a forced drive state.

When the air mix damper 5 is not closed (NO in step S5), reheating is performed by the heater core 4 and cold / hot air is mixed on the air downstream side of the heater core 4, so that the evaporator 15 is used. Even if the cooling action is intermittent, the temperature fluctuation of the air blown into the vehicle interior is alleviated. Therefore, even if the compressor 11 is intermittently controlled, the air conditioning feeling is hardly adversely affected. Therefore, the compressor connection / disconnection control for connecting / disconnecting the compressor 11 is performed based on the temperature T detected by the temperature sensor 25 downstream of the evaporator 15 (step S6).

As described above, in the compressor intermittent control, when the detected temperature T becomes 3 ° C. or less, the electromagnetic clutch 17 is de-energized to stop the compressor 11 and the detected temperature T becomes 4 ° C.
When the above is reached, energize the electromagnetic clutch 17 again,
Although the compressor 11 is operated, in a state where the compressor 11 is temporarily stopped, if the determinations in steps S2, S4, and S5 are YES, regardless of the compressor intermittent control in step S6, The electromagnetic clutch 17 is immediately energized to drive the compressor 11. When the air conditioner switch is off (NO in step S1), the electromagnetic clutch 17 is not energized and the compressor 11 is not driven (step S7).

By performing the above control operation, in the present embodiment, when the vehicle is traveling at a predetermined speed or more without being decelerated by a predetermined speed, the compressor is adjusted according to the temperature downstream of the evaporator 15. Since 11 is controlled intermittently, fuel consumption can be improved without deteriorating the air conditioning feeling. Further, when the vehicle speed decreases, the compressor 11 is brought into a driving state before the vehicle stops, so that the idle speed of the engine does not change during the stop. Therefore, comfortable air conditioning operation can be ensured.

FIG. 3 shows the control operation of the air conditioner controller 20 according to the second embodiment of the present invention. In this embodiment, instead of determining the vehicle speed in the above embodiment, the engine speed is determined. In step S2, it is determined whether or not the traveling speed of the vehicle is decelerating, and in step S3, The engine speed is a predetermined speed (eg 1200 rpm)
If it is decelerated in step S2 (YES) or if the engine speed is smaller than the predetermined speed in step S3 (YES),
In each of the steps S3, the electromagnetic clutch 17 is energized to operate the compressor 11. If NO in both steps S2 and S4, the air mix damper 5 is determined in step S5. Also in this embodiment, E
It is possible to improve fuel efficiency while ensuring a certain degree of comfort as an air conditioner provided with the PR 16.

Comparing the first embodiment and the second embodiment, in the first embodiment, the compressor intermittent control is performed based on the vehicle speed instead of the engine speed, so that, for example, in an automatic vehicle, traveling is performed. Automatic shifting is done in
Even if the engine speed decreases, if the above conditions are satisfied, the compressor 11 is not driven, and the energy saving effect is greater than in the second embodiment. .. Further, when the accelerator is repeatedly stepped on when the vehicle is stopped and the idling speed changes greatly, in the second embodiment, depending on the discriminating value of the engine speed, the compression is performed when the engine speed becomes high. In contrast to the case where the compressor 11 may be turned off, in the first embodiment, if the above conditions are satisfied, the compressor 11 is not driven. Accordingly, the electromagnetic clutch 17 is not repeatedly turned on and off.

FIG. 4 shows the control operation of the air conditioner controller 20 according to the third embodiment of the present invention. In the third embodiment, in Step 5, instead of determining the opening degree of the air mix damper 5, a pipe temperature sensor 26 (see FIG. 1) that detects the pipe temperature on the downstream side of the EPR 16 in the refrigeration cycle 10 is provided. When the pipe temperature is higher than a predetermined temperature (for example, -5 ° C) (YES), the electromagnetic clutch 17 is energized to forcibly operate the compressor 11, and when the temperature is lower than the predetermined temperature (NO), the compressor is interrupted. Get control. here,
When the temperature of the pipe downstream of the EPR 16 is low, the cooling load is sufficiently small, and the EPR 16 increases the evaporation pressure of the refrigerant in the evaporator 15. Therefore, at this time, the air mix damper 5 is closed. There is no state.

FIG. 5 shows an example of the actual measurement result of the fuel consumption increase rate according to the present invention. Here, the displacement of the car engine is 3
000cc, outside temperature 25 ° C, humidity 50%, speed 40k
m / h. As is clear from the figure, it is understood that the fuel consumption increase rate is not so large in the case of using the EPR and further controlling the compressor on / off based on the air temperature on the downstream side of the evaporator.

In each of the above-mentioned embodiments, the vehicle speed signal or the engine speed signal is combined with the deceleration signal for determination, but the vehicle speed signal and the engine speed signal may be combined with each other for determination. In each of the above embodiments, the air mix damper is used as the temperature adjusting means for adjusting the heating amount by the heater core, but a valve for adjusting the amount of engine cooling water circulating in the heater core may be used. .. Further, in each of the above embodiments, the temperature of the air downstream of the evaporator is detected by the temperature sensor in order to detect the degree of cooling by the evaporator, but the fin temperature of the evaporator may be detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an automobile air conditioner of the present invention.

FIG. 2 is a flow chart for explaining the control operation of the first embodiment of the air conditioner control device for an automobile air conditioner according to the present invention.

FIG. 3 is a flow chart for explaining a control operation of a second embodiment of an air conditioner control device for an automobile air conditioner showing the present invention.

FIG. 4 is a flow chart for explaining a control operation of a third embodiment of the air conditioner control device for an automobile air conditioner showing the present invention.

FIG. 5 is a characteristic diagram showing a fuel consumption increase rate for explaining the effect of the automobile air conditioner of the present invention.

[Explanation of symbols]

1 Automotive Air Conditioner 2 Air Conditioning Duct 4 Heater Core 5 Air Mix Damper (Temperature Adjustment Means) 10 Refrigeration Cycle 11 Compressor 15 Evaporator 16 EPR (Pressure Adjustment Valve) 17 Electromagnetic Clutch 20 Air Conditioner Control Device (Compressor Intermittent Control Means, Compression) Machine forced drive means) 25 Temperature sensor (cooling state sensor) 30 Engine control device (detection means)

Claims (2)

[Claims] 1. A compressor driven by an engine via an electromagnetic clutch, an evaporator in a refrigeration cycle in which a refrigerant is circulated by the compressor, and a constant evaporation pressure of the refrigerant in the evaporator in the refrigeration cycle. A pressure adjusting valve adjusted as described above, a heater core that circulates the cooling water of the engine, an air conditioning duct that blows air into the vehicle interior by sequentially disposing the evaporator and the heater core, and an amount of air heated by the heater core. A temperature adjusting means for adjusting, a cooling state sensor for detecting a physical quantity related to a cooling degree of the evaporator in the air-conditioning duct, and an on / off control of the electromagnetic clutch based on a detection signal of the cooling state sensor to control the compression. Compressor intermittent control means for controlling the drive of the compressor, and at least one of the running state of the vehicle and the engine speed. And a detection unit that outputs the signal, and when the detection unit detects at least one of a state where the vehicle traveling speed is equal to or lower than a predetermined speed or a state where the engine speed is equal to or lower than a predetermined speed, the electromagnetic clutch is energized to force the compressor. Air conditioner for a vehicle, comprising: 2. The compressor forced drive means energizes the electromagnetic clutch to force the compressor even when the temperature adjusting means is in a maximum cooling state in which the amount of air heated by the heater core is zero. The automobile air conditioner according to claim 1, which is configured to be driven.