JP2791705B2 - Automotive air conditioning controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a control system for controlling a discharge capacity of a variable displacement compressor used in a vehicle air conditioning control device, particularly, a cooling cycle.

(Prior Art) Various failure diagnoses have conventionally been considered because it is necessary to appropriately control a cooling cycle mounted on an automobile when an abnormality occurs. For example, in JP-A-52-76752, temperature sensors are provided at two points in the cooling cycle system, for example, before and after an evaporator, and in a normal state, there is not much temperature difference between these two points, and the refrigerant discharged from the compressor is small. In such a case, that is, when there is a leaking refrigerant, in consideration of the fact that the temperature difference between the two points detected by the temperature sensor is equal to or more than a predetermined value, the alarm load is activated in such a case. Something is considered.

(Problems to be Solved by the Invention) However, in a cooling cycle using a variable displacement compressor that has been commercialized in recent years, the discharge capacity of the compressor is set to be small when the heat load on the evaporator is small. However, there is a possibility that the temperature between the two points becomes large even though there is no leaking refrigerant, and that there is a refrigerant leak. For this reason, when a variable displacement compressor is used, there is a drawback that refrigerant leakage cannot be substantially detected.

Further, according to the above-described technology, malfunctions other than refrigerant leakage, such as a case in which air blow to the evaporator is not performed due to a malfunction of a relay that controls locking of the blower and its drive, a power transistor, and the like, are caused. I can not cope. That is, if the airflow is expected but there is no airflow, the temperature difference of the temperature sensor is eliminated (the heat load on the evaporator is eliminated), so that the cooling cycle continues to operate as in the normal state. In particular, air-thermo-sensing systems are increasingly used as thermosensors today. May not return to the compressor and there is a risk that the compressor will burn due to lack of oil.

Therefore, in the present invention, even in the case where the variable capacity compressor is provided in the cooling cycle, it is possible to detect the refrigerant leakage at the time of low load, and even if there is an abnormality in the blower system other than the cooling cycle, the refrigerant cycle is controlled. An object of the present invention is to provide an air conditioning control device for a vehicle that can appropriately perform control and prevent burning of a compressor.

(Means for Solving the Problems) However, the gist of the present invention is that, as shown in FIG. 1, an evaporator 8 through which absorbed air passes and a variable capacity capable of changing a discharge capacity. A cooling cycle including the compressor 18, evaporator outlet temperature calculating means 100 for calculating a target outlet temperature after the evaporator 8 based on at least the vehicle interior temperature and the vehicle interior set temperature, and based on at least the vehicle interior temperature and the outside air temperature. The heat load on the evaporator 8 is calculated based on the outputs of the evaporator intake air temperature calculating means 200 for calculating the air temperature on the suction side of the evaporator 8 and the evaporator outlet temperature calculating means 100 and the evaporator suction air temperature calculating means 200. Heat load calculating means 300 for calculating, and the variable capacity compressor based on the output of the heat load calculating means 300. A compressor discharge capacity calculating means 400 for calculating the discharge capacity of 18, a heat load determining means 500 for determining whether or not the heat load on the evaporator 8 calculated by the heat load calculating means 300 is equal to or more than a predetermined load; If the thermal load determining means 500 determines that the thermal load on the evaporator 8 is equal to or less than a predetermined load, the actual discharge capacity of the variable displacement compressor 18 is calculated by the compressor discharge capacity calculating means 400. Discharge capacity determination means 60 for determining whether or not a
If the discharge capacity is not greater than a predetermined value by 0 and the discharge capacity determination means 600, the variable capacity compressor 18 is operated with the discharge capacity calculated by the compressor discharge capacity calculation means 400, A compressor control means 700 for stopping the operation of the variable capacity compressor 18 when the discharge capacity is continuously exceeded a predetermined value by the capacity determination means 600.

(Operation) Therefore, the heat load on the evaporator is calculated without using the thermo sensor, and the discharge capacity of the actual compressor continues for a predetermined time with respect to the discharge capacity of the variable capacity compressor calculated based on this heat load. If it exceeds, there is a possibility that the refrigerant leaks from the compressor, and the operation of the compressor is stopped. Also, even if the blower breaks down and is no longer blown to the evaporator, the heat load of the evaporator is performed without using a thermosensor in the first place. There is no danger of burning. Therefore, the above object can be achieved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 2, the air-conditioning control device for an automobile is provided with an intake door switching device 2 at the most upstream side of the air conditioning duct 1, and the intake door switching device 2 is provided at a portion where the inside air inlet 3 and the outside air inlet 4 are separated. An inside / outside air switching door 5 is disposed, and the inside / outside air switching door 5 is operated by an actuator 6 so that 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. An evaporator 8 and a heater core 9 are provided behind the blower 7.

An air mix door 10 is provided in front of the heater core 9, and the opening degree of the air mix door 10 is adjusted by an actuator 11 so that the air passing through the heater core 9 and the air bypassing the heater core 9 are separated. The proportion is adjusted.

Further, the downstream side of the heater core 9 has a defrost discharge port.
12 、 Vent outlet 13 and heat outlet 14
Opened at 15, and the mode doors 16a, 16b, 16
c is provided, and by operating the mode doors 16a, 16b, 16c with the actuator 19, the blowing mode can be switched.

The evaporator 8 constitutes a cooling cycle together with a variable capacity compressor 18, a condenser 19, a liquid tank 20, and an expansion valve 21 described below.

The variable displacement compressor 18 is connected to an engine 22 of the vehicle via an electromagnetic clutch 23 to use the engine 22 as a drive source, and the variable displacement compressor 18 is provided with a displacement varying means 24. If the variable capacity compressor 18 is, for example, a wobble plate type, the capacity variable means 24 is a known means that changes the amount of return to the discharge gas suction side to change the discharge capacity of the compressor. 3
It is shown in the figure.

In FIG. 3, the variable displacement compressor 18 is provided with a wobble plate 28 in the crank chamber 25 which is allowed to swing only with a hinge ball 27 fitted on the drive shaft 26 as a fulcrum. Is connected to a plurality of pistons 30 inserted into the cylinder bore 29, and the reciprocating motion of the piston 30 compresses the refrigerant sucked from the low-pressure chamber 31 and discharges the refrigerant to the high-pressure chamber 32. Further, the variable displacement compressor 18 is provided with a pressure control valve 33 constituting the displacement varying means 24 so as to face the crank chamber 25. This pressure control valve 33
The suction chamber 34 communicating with the low-pressure chamber 31 and the crank chamber
25, a pressure responsive member 36 for moving the valve body 35 according to the pressure in the suction chamber 34, and the valve body 35 forcibly controlled by the amount of power I _SOL to the electromagnetic coil 37. And a solenoid 38 that can be moved manually.

Thus, for example, when the current flowing through the electromagnetic coil 37 increases and the magnetic force of the solenoid 38 increases, a force acts on the valve body 35 in a direction to reduce communication between the crank chamber 25 and the suction chamber 34, and the crank chamber 215 moves from the crank chamber 215 to the suction chamber. The amount of refrigerant gas leaking to 34 is reduced. For this reason, the refrigerant gas leaking from the space between the piston 30 and the cylinder bore 29 to the crank chamber 25, that is, the blow-by gas increases the pressure in the crank chamber 25, and the pressure in the crank chamber 25 increases. The acting force increases. For this reason, the wobble plate 28
The rotation of the piston 30 in the direction in which the swing angle is reduced with the fulcrum 27 as the fulcrum, that is, the variable displacement compressor 18
Is smaller.

The actuators 6, 11, 17, the motor of the blower 7, the electromagnetic clutch 23 of the variable capacity compressor 18 and the capacity changing means 24 are controlled based on output signals from the microcomputer 41 via drive circuits 40a to 40f, respectively. Is done.

The microcomputer 41 has a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), an input / output port (I / O), and the like (not shown). The computer 41 has a vehicle interior temperature T _R from a vehicle interior temperature sensor 42 that detects the temperature of the vehicle interior, an outside air temperature T _A from an outside air temperature sensor 43 that detects the temperature of the outside air, and a solar radiation sensor 44 that detects the amount of solar radiation. of solar radiation Q _SUN is selected through the multiplexer 45, is input is converted to a digital signal via an a / D converter 46.

Further, an output signal from the operation panel 47 is input to the microcomputer 41. The operation panel 47 includes manual switches 48a to 48d for switching the rotation speed of the blower 7 between LOW, MED, HI, and MAX HI, and an AUTO for automatically controlling the rotation speed.
A switch 48e, an OFF switch 48f for stopping driving of the blower 7, etc., an A / C switch 49 for operating the variable capacity compressor 18, and a changeover switch 5 for internal air circulation or external air introduction.
0, mode switches 51a to 51d for switching the blowing mode and a temperature setting device 52 are provided.

Temperature setter 52, and more become the display unit 52b for displaying the set temperature T _D and the up-down switch 52a, the switch 52a
By the operation described above, the set temperature shown on the display section 52b can be changed within a predetermined range. The temperature setting device may be of a type in which a template bar is slid.

FIG. 4 shows an example of the control operation of the microcomputer 41 described above as a flowchart. The microcomputer 41 starts executing the program from step 60, and in step 62, the vehicle interior temperature sensor 42,
Signals from the outside air temperature sensor 43, the solar radiation sensor 44, and the operation panel 47 are input. The overall signal at the next step 64, which is utilized for controlling each air-conditioning equipment on the basis of the set temperature T _D set in the vehicle interior temperature Tr, the outside air temperature Ta, the amount of solar radiation Q _SUN and temperature setter 52 computed on the basis of T ₁ to (1).

T ₁ = A · Tr + B · Ta + C · Q _SUN −D · T _D + E (1) where A to E are operation coefficients.

After determining the total signal T ₁ at step 64, at step 66, it obtains the predetermined blowing side target temperature T _E of the evaporator 8 from a predetermined characteristic pattern 'based on the T _1.

Then, in a next step 68, (2) and the suction side air temperature T _E of the evaporator 8 shown in formula, wherein a difference [Delta] T _E between the outlet side target temperature T _E 'calculated in (3), this The heat load applied to the evaporator 8 is used for the following control.

T _E = a · Tr + (1-a) · (Ta + 5) (2) ΔT _E = {a · Tr + (1-a) · (Ta + 5)} − T _E ′ (3) where a is the inside and outside air The inside / outside air ratio determined by the position of the switching door 5 is “1” in the inside air circulation mode (REC) and “0” in the outside air introduction mode (FRESH).

In step 70, thermal load [Delta] T _E is given heat load α for the evaporator 8, which is calculated in step 68,
determining whether β is less than or not, [Delta] T _E is in the case larger than the predetermined heat load proceeds to step 72, to normal control with the techniques used conventionally the variable displacement compressor 18.
Specifically, the current amount I for controlling the pressure control valve 33 is
In proportion integral control _SOL, (4) as shown in the formula, determined by the sum of the I _SOL proportional term I _P and the integral term I _I.

I _SOL = I _P + I _I (4) where I _P is calculated from the heat load (ΔT _E = T _E −T _E ′) of the evaporator 8 so as to obtain the characteristic pattern shown in FIG. I _I is the current value ΔI _I in the minute section at time t
(T) is calculated from the heat load ΔT _E of the evaporator 8 so as to obtain the characteristic pattern shown in FIG.
As shown in equation (5), this is, for example, every 0.5 seconds (Δ
t = 0.5).

I _I (t) = I _I (t−Δt) + ΔI _I (t) (5) where t is the current supply time and I _I (t−Δt) is time t−Δt, that is, 0.5 seconds before Represents the integral term obtained up to.

Then, the I _SOL determined in this way is
supply to the electromagnetic coil 37 through the f
The control is shifted to another control routine via the control routine.

On the other hand, if it is determined in step 70 that the heat load of the evaporator 8 is equal to or less than the predetermined value, the process proceeds to step 74, where the current amount I _SOL supplied to the electromagnetic coil 37 is
Is determined to be a value for obtaining a discharge capacity of the compressor equal to or greater than a predetermined value. In other words, the processing to be performed here should be performed in consideration of the fact that when the heat load is small, I _SOL for reducing the discharge capacity of the compressor should be supplied.
_{If SOL} indicates a value to obtain a large capacity, it means that there is some kind of failure, and this is to be detected.

Therefore, in this step 74, if I _SOL is not the value for obtaining the discharge capacity of the compressor equal to or more than the predetermined value, the process proceeds to step 72 to perform the normal control, and I _SOL is the value for obtaining the discharge capacity of the compressor equal to or more than the predetermined value. Step in case
Proceed to 76 to start a timer to check if this state is temporary and measure the duration of this _ISOL (Time). Then, in the next step 78, it is determined whether or not this Time has continued for a predetermined time γ, and although the I _SOL value for obtaining a low capacity must be output, the I _SOL value for obtaining a high capacity is obtained. If the time continues for a predetermined time or more, it is considered that an inconvenience such as a refrigerant leak has occurred.
Then, the variable capacity compressor 18 is stopped.

Therefore, it is not necessary to obtain a thermal load on the evaporator 8 by providing a thermo sensor on the suction side or the discharge side of the evaporator 8, so that even if the blower 7 breaks down and the air supply to the evaporator 8 is stopped, the refrigerant cycle system Is not directly affected.

(Effect of the Invention) As described above, according to the present invention, the heat load of the evaporator is detected without using the thermo sensor, and the discharge capacity at the time of actual low load of the compressor is calculated from the heat load of the evaporator. Since the compressor is stopped when the capacity becomes larger than the capacity for a predetermined time, it is possible to detect the refrigerant leakage even when the load of the evaporator is low, and a failure has occurred in the blower other than the cooling cycle or its drive system. Even in such a case, the discharge capacity of the compressor is appropriately corrected to prevent burning of the compressor.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing the present invention, FIG. 2 is a schematic diagram showing a vehicle air-conditioning control device according to the present invention, FIG. 3 is a sectional view showing a variable displacement compressor used in the same, FIG. Is a flowchart showing an example of control of the discharge capacity of the compressor by the microcomputer, FIG. 5 is a characteristic diagram used for calculating a proportional term used in the process of calculating the discharge capacity of the compressor, and FIG. FIG. 4 is a characteristic diagram used for calculating an integral term used in FIG. 8 ... Evaporator, 18 ... Variable displacement compressor, 10
0: evaporator outlet air temperature calculation means, 200: evaporator intake air temperature calculation means, 300: heat load calculation means, 400: compressor discharge capacity calculation means, 500: heat load determination means, 600: discharge capacity Judgment means, 700 ... Compressor control means.

Claims (1)

(57) [Claims] 1. A cooling cycle including an evaporator through which inhaled air passes and a variable capacity compressor capable of changing a discharge capacity, and a target blowout after the evaporator based on at least a vehicle interior temperature and a vehicle interior set temperature. Evaporator outlet temperature calculating means for calculating the temperature; evaporator inlet air temperature calculating means for calculating the air temperature on the suction side of the evaporator based on at least the vehicle interior temperature and the outside air temperature; the evaporator outlet temperature calculating means and evaporator suction Heat load calculating means for calculating a heat load on the evaporator based on an output from the air temperature calculating means; compressor discharge capacity calculating means for calculating a discharge capacity of the variable displacement compressor based on an output of the heat load calculating means; The evaporator calculated by the heat load calculator A heat load determining means for determining whether a heat load on the evaporator is equal to or more than a predetermined load; and a variable capacity when the heat load on the evaporator is determined to be not more than a predetermined load. A discharge capacity determining means for determining whether or not the actual discharge capacity of the compressor exceeds the discharge capacity calculated by the compressor discharge capacity calculating means for a predetermined time; and a discharge capacity determined by the discharge capacity determining means. If not exceeding the predetermined value, the variable displacement compressor is operated with the discharge capacity calculated by the compressor discharge capacity calculating means, and if the discharge capacity continues to exceed the predetermined value by the discharge capacity determining means, A compressor control means for stopping the operation of the variable displacement compressor. Control device.