JPH0659772B2 - Air conditioning controller for automobile - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle air conditioning control device having a function of preventing freezing of an evaporator.

(Prior Art) In order to prevent the evaporator used in the cooling cycle from freezing, it is a common practice to stop the compressor when the cooling temperature of the evaporator falls below a predetermined temperature. Even with such control, the evaporator cooling is required when maximum cooling power is required for rapid cooling of the passenger compartment (cooldown) or when demist performance at low outside air is improved (low temperature demist). It is desirable to keep the compressor operating even when the temperature falls below the freezing start temperature (around 0 ° C).

(Problems to be solved by the invention) However, if the antifreezing function starts to operate again immediately after the cool down control or the low temperature demist control is performed, if the cooling of the evaporator is still below the freezing start temperature, the compressor is It stops unnecessarily. Then,
When the compressor is stopped by the antifreezing function when the cooldown control is performed, the blowout temperature rises rapidly and comfortable temperature control is impaired. Further, there is a problem that the window glass suddenly becomes cloudy when the low temperature demist control is performed.

Therefore, an object of the present invention is to provide an automobile air conditioning control device that solves the above problems, eliminates unnecessary stoppage of the compressor during air conditioning control, and can perform stable air conditioning control.

(Means for Solving the Problem) The gist of the present invention is, as shown in FIG. 1, an evaporator 8 through which sucked air passes, and a compressor 18 for supplying a refrigerant to the evaporator 8. And a mode sensor 45 for detecting the cooling temperature of the evaporator 8, and the compressor 18 is stopped when the cooling temperature of the evaporator 8 is equal to or lower than a predetermined value set in advance to prevent freezing. Anti-freezing control means 100 for causing the evaporator 8
Determination means 200 for determining whether or not the cooling temperature of the evaporator 8 belongs to a predetermined environment requiring the operation of the compressor 18 even if the cooling temperature of the evaporator 18 is lower than the predetermined value, and the cooling temperature of the evaporator 8 is determined by the determination means 200. When it is determined that the evaporator 8 belongs to the environment, the function of the freeze prevention control means is invalidated, and the evaporator 8 is determined by the determination means 200.
When it is determined that the cooling temperature of the evaporator 8 does not belong to the predetermined environment, the freezing prevention control means 10 starts when the cooling temperature of the evaporator 8 exceeds the predetermined temperature at which freezing can be prevented.
And a limiting means 300 for returning the function of 0.

(Effect) Therefore, even if the cooling temperature of the evaporator falls below the freezing start temperature due to the antifreezing function being disabled and the condition for disabling the antifreezing function no longer holds, the cooling temperature of the evaporator can be prevented from freezing. If the temperature does not exceed the temperature, the antifreezing function does not return, and the compressor will not stop during the air conditioning control even though it is not necessary. Therefore, the above problem can be achieved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, an air conditioner for a vehicle is provided with an intake switching device 2 on the most upstream side of an air conditioning duct 1, and this intake switching device 2 switches between inside air and outside air at a portion where an inside air inlet 3 and an outside air inlet 4 are separated. A door 5 is arranged so that a desired suction mode can be obtained in which the inside / outside air switching door 5 is operated by an actuator 6 so that the air introduced into the air conditioning duct 1 can be selected from inside air and outside air.

The blower 7 sucks air into the air conditioning duct 1 and blows the air downstream, and an evaporator 8 and a heater core 9 are provided behind the blower 7. Further, an air mix door 10 is provided in front of the heater core 9, and the air passing through the heater core 9 and the air bypassing the heater core 9 are adjusted by adjusting the opening of the air mix door 10 with an actuator 11. And the resulting air is temperature controlled.

The downstream side of the air conditioning duct 1 is divided into a defrost outlet 12, a vent outlet 13, and a foot outlet 14 to open in the vehicle compartment, and a mode door 15 is provided at the divided portion.
a and 15b are provided, and the mode doors 15a and 15b are provided.
By operating the actuators 16 and 17, a desired blowout mode can be obtained.

The evaporator 8 constitutes a cooling cycle together with a compressor 18, a condenser 19, a liquid tank 20 and an expansion valve 21 described below. The compressor 18 is, for example, a wobble plate type, and as shown in FIG.
The drive shaft 24 connected to 2 is inserted into the compressor body 25, and the wobble plate 26 is connected to the drive shaft 24 via the hinge balls 27. The wobble plate 26 is swingably supported by a crank chamber 28 formed in the compressor body 25 with respect to the drive shaft 24 with a hinge ball 27 as a fulcrum.
The piston 29 connected to 6 is reciprocated in the cylinder bore 30 according to the swing angle. Further, the compressor 18 is provided with a pressure control valve 31 as desired in the crank chamber 28, and the pressure control valve 31 adjusts the communication state between the crank chamber 28 and the suction chamber 32 communicating with the suction side, and A pressure responsive member 34 that moves the valve element 33 in accordance with the pressure in the suction chamber 32, and the valve element 33 are connected to the electromagnetic coil 3.
5 has a solenoid 36 that moves in accordance with the amount of electric current I _SOL to the piston 5, and the amount of electric current I _SOL to the electromagnetic coil 35 is externally controlled to control the piston 29 and the cylinder bore 30.
The amount of blow-by gas that leaks into the crank chamber 28 from between and returns to the suction side is adjusted.

Therefore, the capacity varying device 37 for changing the capacity of the compressor 18 is configured from the pressure control valve 31 and the like, and the electromagnetic coil 3
When the amount of current I _SOL flowing through the solenoid valve 5 increases and the magnetic force of the solenoid 36 increases, the crank chamber 28 and the suction chamber 3 are attached to the valve body 33.
A force in the direction of reducing communication with 2 acts, and the amount of blow-by gas leaking from the crank chamber 28 to the suction chamber 32 is reduced.
Therefore, the pressure in the crank chamber 28 increases and the force acting on the back surface of the piston 29 increases, so that the wobble plate 26 rotates about the hinge ball 27 in the direction in which the swing angle decreases, and the piston moves. 29 strokes, that is, the capacity of the compressor is reduced.

The variable capacity device 37 is not only a device that adjusts the amount of blow-by gas returned to the suction side by the pressure control valve, but also a device that changes the number of cylinders used by the compressor, or an effective vane in a vane type compressor. It is possible to change the capacity substantially, such as changing the number of sheets.

The actuators 6, 11, 16 and 17, the motor 7a of the blower 7, the electromagnetic clutch 23 of the compressor 18 and the capacity varying device 37 are respectively driven by a drive circuit 40a.
Is controlled on the basis of the output signal from the microcomputer 41 via the .about.40f. The microcomputer 41 is a well-known computer having a central processing unit (CPU), a read only memory (ROM), a random accelerator memory (RAM), an input / output port (I / O), etc., which are not shown. Reference numeral 41 denotes an output signal from a vehicle interior temperature sensor 42 that detects the temperature in the vehicle compartment, an output signal from an outside air temperature sensor 43 that detects the outside air temperature, an output signal from a solar radiation sensor 44 that detects the amount of solar radiation, and the evaporator. 8 is provided downstream of the temperature of the evaporator 8 or the evaporator 8
The temperature of the air passing through the
The output signal from the mode sensor 45, which is detected as _INT, is selected via the multiplexer (MPX) 46, converted into a digital signal via the A / D converter 47, and input.

The microcomputer 41 has an operation panel 48.
The output signal from is input. This operation panel 48 is
Set the AUTO switch 49 that releases the stop mode or manual operation state and set all the air conditioners such as the blower to the automatic state, the OFF switch 50 that commands the stop mode, the A / C switch 51 that operates the compressor 18, and the suction mode. Intake switch 52 to switch between indoor air intake mode (REC) and outdoor air intake mode (FRESH), DFF switch 53 to set blowout mode to defrost mode, blower capacity setting device 55 to set blower capacity, set blowout mode other than defrost mode The blowout mode setting device 56 is provided.

The temperature setting device 54 includes up / down switches 54a and 54b.
And a temperature display section 54c that digitally displays the set temperature T _D , and the set temperature shown on the temperature display section 54c can be changed within a predetermined range by operating the up / down switches 54a and 54b.

The blower capacity setting device 55 includes a FAN switch 55a for switching the rotation level of the blower 7 and a level display section 55b for displaying the current rotation level.
Blower capacity mode is stopped by operating 5a (level 0), LO
W (Level 1), MID (Level 2), HI (Level 3), MA
The characters are sequentially switched in the order of X HI (level 4), and the letters "MANUAL" are lit on the upper part of the level display portion 55b.

Further, the mode setting device 56 is a MODE switch 56a for sequentially switching the blowout mode in the order of vent, bilevel, and heat.
And a picture display section 56b showing the current blowing mode as a picture display, and the picture display section 56b can be operated by operating the MODE switch 56a.
The air flow arrows 57a and 57b are lit and displayed to indicate the selected blowing mode, and the letters "MANUAL" are lit above the picture display portion 56b. These lighting displays 57a and 57b are used for the display units 54c and 55, respectively.
The display of b and 56b is controlled by the microcomputer 41 via the display circuit 58.

In FIG. 4, an example of the control operation of the compressor 18 by the microcomputer 41 described above is shown as a flowchart, and the microcomputer 41 determines whether or not the cool down control is being performed in step 60.
Further, in step 62, it is determined whether or not the low temperature demist control is being performed.

In the cooldown control, specifically, the target outlet temperature X _M is obtained from the set temperature T _D vehicle interior temperature T _R , the outside air temperature T _A , and the amount of solar radiation Q _S by, for example, the following formula: X _M = A · T _D + B · _{T R + C · T a +} D · Q S + E ( where, a, B, C, D , E represents a processing constant) the X _M is started when the required maximum cooling capacity equal to or less than a predetermined value It is something.

On the other hand, the low temperature demist control is, for example, a demist control started when the outside air temperature T _A belongs to a predetermined low temperature region (for example, −6 ° C. to 6 ° C.). Although these calculations and determination processes are not shown, they are performed in a main routine (not shown) before executing this routine in advance.

If it is determined in step 60 that the cool-down control is being performed, the process proceeds to step 64, and the condition of the cool-down control described above is not satisfied, and it is safe to end the cool-down control so that the vehicle interior environment is acceptable. determines whether, the process proceeds to step 66 in the case (NO) cool down control is still necessary, freeze starting temperature (0 of the evaporator 8 as the target cooling temperature T _'INT of the evaporator 8 for example -10 ° C. The temperature is set to a predetermined temperature α which is considerably lower than the temperature (around ° C). In this case, the capacity of the compressor 18 is proportionally integrated so that the difference between the actual cooling temperature T _INT of the evaporator 8 and the target cooling temperature _T'INT , which will be described later, becomes the relationship shown in the equation (2). The evaporator cooling temperature T _INT is set close to the target cooling temperature T ′ _INT .

| T _INT −T ′ _INT | <1 ° C. (2) Equation (2) Therefore, during the cool down control, the capacity of the compressor 18 becomes maximum and the cooling temperature T _INT of the evaporator 8 becomes the freezing start temperature. The compressor 18 is not stopped even if it falls below the temperature, and the vehicle interior is rapidly cooled.

When it is determined in step 62 that the low temperature demist control is being performed (YES), the process proceeds to step 70, it is determined whether or not the environment is in which it is safe to end the low temperature demist control, and the low temperature demist control is performed. in the case (NO) it is still necessary, to set, for example, as shown in FIG. 5, by switching alternately the target cooling temperature T _'INT of the evaporator 8 to the beta ₁ and beta ₂ (step 72), then step Proceed to 68 to control the capacity of the compressor based on this _T'INT .

Therefore, during the low temperature demist control, the cooling temperature T _INT of the evaporator 8 intermittently becomes lower than the freezing start temperature, so that the dehumidifying ability can be sufficiently obtained even in the low outside air.

On the other hand, if it is determined in step 64 or 70 that the environment is such that the cool down control or the low temperature demist control is ended, then step 74 or 76 is performed.
Go to and set the flag to request the end of these controls to "1".
Set to step 7 as in normal compressor control.
8, the target cooling temperature T'in this step 78
_INT is set to a set value γ (for example, 3 ° C.) during normal control. Then, in step 80, the flag is set to "1".
If it is not “1”, it is determined in step 82.
Going to, the cooling temperature T _INT of the evaporator 8 and the predetermined values T ₂ and T ₃ (for example, T ₂ = 1.5 ° C. and T ₃ = 3 ° C.) set in advance to prevent the evaporator 8 from freezing are set. Is compared and judged. In this step 82, T
_{When INT} is larger than the predetermined value (A), the compressor capacity control is continued in step 68 described above, but when it is smaller than the predetermined value (B), the routine proceeds to step 84, and the compressor 18 is stopped immediately. To prevent the evaporator 8 from freezing.

On the other hand, when it is determined in step 80 that the flag is "1", the process does not immediately proceed to step 82 but proceeds to step 86 to determine whether or not the cooling temperature T ₁ of the evaporator 8 (for example, 1.5 ° C.) is exceeded. Is judged, T _INT is T
If it is smaller than _{1, the} compressor 18 is immediately stopped in step 82 even if the control is returned to the normal control.
2 is bypassed and the routine proceeds to step 68, and if T _INT ≧ T ₁ , the compressor 18 does not immediately stop even if the normal control is restored, so the routine proceeds to step 88 where the flag is set to “0” and then Proceeding to step 82, the freeze prevention function of the evaporator is restored.

Incidentally, after step 68, the routine shifts to another air conditioning control routine, and then returns to step 60.

Therefore, in the process of shifting from the cool-down control or the low temperature demist control to the normal control, even if the cooling temperature T _INT of the evaporator 8 is T ₂ or less, the compressor 18 continues to operate with a small capacity without stopping. The air conditioning in the vehicle compartment does not change significantly during the transition to the normal control. Also, at the same time as shifting to the normal control, the compressor 18
If the control is stopped, it is meaningless to perform the cool down control or the low temperature demist control, but by guaranteeing the operation of the compressor as described above, the effects of these controls can be sufficiently brought out.

(Effects of the Invention) As described above, according to the present invention, when the disabled antifreezing mechanism is restored, the cooling temperature of the evaporator is equal to or higher than the predetermined temperature at which freezing can be prevented.
Even if the anti-freezing function returns, the compressor will not stop at the same time, and unnecessary stop of the compressor during air conditioning control can be prevented and stable air conditioning control can be realized.

[Brief description of drawings]

1 is a functional block diagram showing the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a sectional view showing a compressor used therein, and FIG. 4 is a compressor control by a microcomputer. FIG. 5 is a flowchart showing an operation example, and FIG. 5 is a characteristic diagram showing changes in the evaporator target cooling temperature T ′ _INT and the actual evaporator cooling temperature T _{INT in} the low temperature demist control. 8 ... Evaporator, 18 ... Compressor, 45 ...
Mode sensor, 100 ... Freezing prevention control means, 200 ...
... judgment means, 300 ... control means.

Claims (1)

[Claims] 1. A cooling cycle that includes an evaporator through which sucked air passes and a compressor that supplies a refrigerant to the evaporator, a mode sensor that detects a cooling temperature of the evaporator, and a cooling temperature of the evaporator prevents freezing. In order to stop the compressor when it becomes less than or equal to a predetermined value set in advance, and in a predetermined environment that requires the operation of the compressor even if the cooling temperature of the evaporator falls below the predetermined value. If it is determined that the cooling temperature of the evaporator belongs to the predetermined environment by the determination unit that determines whether or not it belongs, the function of the freeze prevention control unit is invalidated, and the determination unit determines If it is determined that the cooling temperature of the evaporator does not belong to the predetermined environment, the evaporator An air conditioning control device for an automobile, comprising: a limiting unit that restores the function of the antifreezing control unit when the cooling temperature of the unit exceeds a predetermined temperature at which the freezing can be prevented.