JPH0442203B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to an automotive air conditioning control system that attempts to accurately control the capacity of a compressor by accurately detecting the degree of cooling of an evaporator that constitutes a refrigeration cycle. It is related to the device.

(Prior Art) In general, the degree of cooling of an evaporator can be detected by detecting the refrigerant pressure or the related refrigerant temperature (detected as the surface temperature of the evaporator), or by detecting the temperature of the heat-exchanged air in the evaporator (detected as the surface temperature of the evaporator). There are some that detect the temperature on the downstream side.

(Problem to be Solved by the Invention) However, in the former method of detecting refrigerant pressure or refrigerant temperature, when the heat load on the evaporator is high, the heat exchange efficiency of the evaporator is 100%.
%, the refrigerant temperature and the temperature on the downstream side of the evaporator are not equal, and even if the refrigerant temperature is detected, the temperature on the downstream side of the evaporator cannot be accurately determined.

On the other hand, in the latter method of detecting the temperature on the downstream side of the evaporator, there is no problem in the refrigeration cycle of a conventional fixed capacity compressor, but when using an external variable capacity compressor, the temperature on the downstream side of the evaporator can be detected by the demisting capacity. A problem arises when determining this as a guideline. In other words, a refrigeration cycle using an external variable capacity compressor generates a small capacity operation of the compressor from the outside, gradually cools down to below the freezing temperature, and prevents sudden freezing. This is intended to ensure the demisting ability, but if the method of detecting the air temperature on the downstream side of the evaporator is used as described above, even in the case of partial freezing or slight freezing without any actual damage, the air temperature on the downstream side of the evaporator will be The temperature near the temperature sensor on the side rises, even though freezing does not really affect the compressor's operation and the demisting ability can be maintained.
Since the microcomputer determines that the demisting capacity has decreased, there is a problem in that it is not possible to accurately detect the degree of cooling of the evaporator body, which is a measure of the operating capacity of the compressor.

Therefore, the present invention solves the above-mentioned conventional problems and provides an air conditioning control device for automobiles that can accurately detect the degree of cooling of the evaporator body, which is a measure of compressor operating capacity, in a refrigeration cycle using an external variable capacity compressor. The challenge is to provide this.

(Means for Solving the Problems) The gist of the present invention is, as shown in FIG. , an external variable compressor 10 that forms a part of the refrigeration cycle together with the evaporator 8 and controls the capacity from the outside; a refrigerant capacity state detection means 26 that detects the refrigerant temperature or refrigerant pressure of the evaporator 8; An evaporator downstream temperature detection means 17 that detects the temperature of the air immediately after the evaporator, and an outside air temperature determination means 200 that determines the outside air temperature detected by the outside air temperature sensor 31.
When the judgment result of the outside air temperature judgment means 200 is above a predetermined temperature, the detected value by the evaporator downstream temperature detecting means 17 is used, and when the judgment result is below the predetermined temperature, the detected value by the refrigerant capacity state detecting means 26 is used for evaporator cooling. The present invention is provided with a detection switching means 300 that outputs the degree of cooling as the degree of cooling of the evaporator, and a capacity control means 400 that appropriately controls the capacity of the external variable capacity compressor based on the evaporator cooling degree inputted from the detection and switching means 300.

(Function) Therefore, the detection values of the refrigerant capacity state detection means and the evaporator downstream temperature detection means are constantly output to the detection switching means. On the other hand, when the outside air temperature determining means determines that the detected value of the outside air temperature sensor is equal to or higher than the predetermined temperature, a signal indicating this is sent to the detection switching means, and this detection sensing means uses this signal to cool the evaporator. The temperature detected by the temperature detection means on the downstream side of the evaporator is selected as the temperature, and a signal of this detected temperature is output to the capacity control means. Further, when the outside air temperature determining means determines that the detected value of the outside air temperature sensor is below a predetermined temperature (freezing temperature), a signal indicating this is sent to the detection switching means, and the detection sensing means receives this signal. The capacity state detected by the refrigerant capacity state detection means is selected as the evaporator cooling degree, and a signal of this capacity state is output to the capacity control means. The capacity control means appropriately controls the capacity of the external variable capacity compressor based on the input evaporator cooling degree (capacity state detected by the evaporator downstream temperature detection means or the refrigerant capacity state detection means), so that the heat load can be reduced. Even when the cooling temperature is at its maximum or when the cooling temperature is low, the degree of cooling of the evaporator can be accurately detected, thereby achieving the above object.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, the automotive air conditioner is provided with an inside air inlet 3 and an outside air inlet 4 on the most upstream side of the air conditioning duct 1, and an inside/outside air switching door 5 at the part where the inside air inlet 3 and outside air inlet 4 are separated. By operating the inside/outside air switching device 2 consisting of the inside/outside air switching door 5 and the actuator 6 connected thereto, the air to be introduced into the air conditioning duct 1 is selected between inside air and outside air. Inhalation mode is now available.

The blower 7 sucks air into the air conditioning duct 1 and blows it downstream, and an evaporator 8 is disposed behind the blower 7. This evaporator 8 is a variable capacity compressor 1 as described below.
0, a condenser 11, a receiver tank 12, and an expansion valve 13 are connected via piping to form a refrigeration cycle, and the variable capacity compressor 10 is controlled to stop driving by connecting and connecting an electromagnetic clutch 15 to an automobile engine 14. and its capacity is controlled by an external output. A refrigerant temperature sensor 26, such as a thermistor, for detecting the refrigerant temperature T _REF (detected as the surface temperature of the evaporator) is provided at an appropriate position within or outside the evaporator 8.

Immediately after the evaporator 8, a mode sensor 17 such as a thermistor is arranged to detect the evaporator downstream temperature _TINT , which is the temperature of the air immediately after passing through the evaporator 8. Furthermore, a heater core 9 is arranged behind it, and an air mix door 16 is provided upstream of this heater core 9. By adjusting the opening degree _ΘX of this air mix door 16 with an actuator 18,
Air passing through the heater core 9 and the heater core 9
By changing the amount of air that is bypassed, the temperature of the blown air can be controlled.

On the downstream side of the air conditioning duct 1, a defrost outlet 19, a vent outlet 20, and a foot outlet 21 open into the vehicle interior 22, and mode doors 23, 24 are provided at each outlet. The mode doors 23 and 24 are operated by an actuator 25.
A desired blowing mode can be obtained by controlling the blowing mode.

The variable capacity compressor 10 is, for example, of a wobble plate type, and as shown in FIG. A wobble plate 52 is coupled via a hinge ball 53. This wobble plate 52 is supported in a crank chamber 53 formed in the compressor main body 51 so as to be swingable with respect to the drive shaft 50 with the hinge ball 53 as an intersection point, and is connected to the wobble plate 52. The piston 54 is made to reciprocate within the cylinder bore 55 depending on the swing angle.

Further, a pressure control valve 57 is provided in the variable capacity compressor 10 so as to face the crank chamber 53. a pressure-responsive member 60 that moves the valve body 59 in accordance with the pressure within the suction chamber 58;
9 is provided with a solenoid 62 that moves according to the amount of energization I _SOL to the electromagnetic coil 61, and by controlling the amount I _SOL of energization to the electromagnetic coil 61 from the outside, the crank chamber is moved from between the piston 54 and the cylinder bore 55. The amount of blow-by gas leaking into 53 and returning to the suction side is adjusted.

Thus, a variable capacity device is configured to change the capacity of the variable capacity compressor 10 from the pressure control valve 57, etc., and when the amount of current I _SOL flowing through the electromagnetic coil 61 increases and the magnetic force of the solenoid 62 increases, the valve body 5
A force acting in the direction of restricting communication between the crank chamber 53 and the absorption chamber 58 acts on the crank chamber 53, and the amount of blow-by gas leaking from the crank chamber 53 to the suction chamber 58 is reduced. For this reason, the pressure inside the crank chamber 53 increases and the force acting on the back surface of the piston 54 increases, so the wobble plate 52 rotates about the hinge ball 52 in a direction that reduces the rocking angle, and the piston 5
The stroke of No. 4, that is, the capacity of the compressor becomes smaller.

Incidentally, the capacity variable device is not limited to one that adjusts the amount of blow-by gas returned to the suction side using a pressure control valve as described above, but also one that changes the number of cylinders used in the compressor, and a belt transmission device that connects the compressor and the engine 14. Any method that substantially changes the capacity may be used, such as a method that changes the pulley ratio of a vane type compressor, or a method that changes the number of effective vanes in a vane type compressor.

The actuators 6, 18, 25,
30 and the motor of the blower 7 are controlled based on output signals from drive circuits 28a, 28b, 28c, 28d, and 28e, respectively. This drive circuit 2
8a to 28d are connected to the microcomputer 27.

On the other hand, a vehicle interior temperature sensor 29 that detects the vehicle interior temperature T _R , an outside temperature sensor 31 that detects the outside air temperature T _A , and a solar radiation sensor 3 that detects the left and right solar radiation amount.
2. Detection signals from the potentiometer 33 that detects the opening degree of the air mix door 10, the mode sensor 17, the refrigerant temperature sensor 26, etc. are selected by the multiplexer 34 and input to the A/D converter 35, where they are converted into digital signals. The signal is converted into a signal and input to the microcomputer 27.

The control panel 36 includes an intake switch 37 for switching the intake door 5 between outside air introduction and internal air circulation, and a mode switch 3 for switching the blowout mode between vent, bilevel, foot, etc.
8. A fan switch 39 that changes the rotational speed of the blower 7, a temperature setting device 40 that sets the set temperature in the vehicle interior, and commands the stop mode of all air conditioning equipment.
OFF switch 41, AUTO switch 42 for automatically controlling each air conditioner, differential switch 43 for commanding defrost mode, commanding economical operation by fuel saving control of the compressor.
It is equipped with an ECON switch 44 and the like, and these setting signals are input to the microcomputer 27.

Next, an example of the operation control of the microcomputer 27 will be explained with reference to the flowchart of the compressor capacity control routine shown in FIG. 3 (the basic flow is shown, but detailed or additional processing is omitted). .

Start from start step 70 and move to the next step
At 71, various signals are input. and,
In the next step 72, it is determined whether or not the fan switch 39 has been pressed (the blower 7 is operating). If YES, the process proceeds to step 73; if NO, the process proceeds to step 74, where the variable capacity The operation of compressor 10 is stopped and the process proceeds to end step 75.

In step 73, the switch operation (OFF switch 41 is pressed or
(ECON switch 44 is pressed twice), it is determined whether a stop signal for the variable capacity compressor 10 is output, and if YES, step 76 is performed.
If NO, proceed to step 74.

In step 76, the refrigerant temperature (detected value of the refrigerant temperature sensor 26) T _REF is determined, and T _REF
If the temperature is below the predetermined temperature, the process proceeds to step 74,
If T _REF is equal to or higher than the predetermined temperature, the process proceeds to step 77.

In step 77, a predetermined outside temperature state (A, B, C, or D) is determined based on the magnitude of the outside air temperature _TA . (For example, _TA > 10 is A, 5 < _TA < 13 is B, -5 < _TA < 7 is C, -2
> T _A to D).

In the next step 78, it is determined whether or not the AUTO switch 42 has been pressed, and if YES (the air conditioner is automatic), the process advances to step 79 and NO.
If so, proceed to step 80 below.

In steps 79, 80, 81, and 82, the outside temperature
It is determined whether T _A is in any of the states A to D, and if the state is D, the process proceeds to step 83 to stop the variable capacity compressor, and the process proceeds to end step 84 to end the control. When the internal air circulation mode (REC) is fixed in state C or state B, a step is activated for the control necessary to prevent window glass fogging.
Proceeds to step 85 and demist control is executed, otherwise the target evaporator downstream temperature T′ _INT
Set the temperature to 3°C (step 94).

When the demist control is executed in step 85, the process proceeds to step 86, where the threshold values T ₁ (OFF→ON) and T ₂ (ON→OFF) for compressor cycling operation control are determined from the outside air temperature T _A. It is determined. Thereafter, in step 87, the evaporator refrigerant temperature T _REF is compared with the above-mentioned T ₁ and T ₂ .
If it is on the B side, the process proceeds to step 88, where the variable capacity compressor 10 is stopped, and the control proceeds to end step 89, where the control ends.If it is on the A side, the process proceeds to step 90, where the target refrigerant temperature T' _REF is selected. That is, depending on the outside air temperature T _A , the temperature T′ _REF1 at which the dehumidifying ability is achieved,
Two target refrigerant temperatures, _T'REF2 , which have self-defrosting ability are determined, and the process proceeds to step 91.

In step 91, the evaporator refrigerant temperature and T' _REF1 and T' _REF2 obtained in step 90 are
two target refrigerant temperatures for a predetermined time T ₂ = 3 minutes,
A switching process is performed every T ₃ =2 minutes, and the process proceeds to step 92, where the discharge capacity of the variable capacity compressor 10 is controlled so that T _REF approaches this T' _REF . On the other hand, under the outside air temperature T _A condition where the transition to demist control is not made, the process proceeds to step 94, where the target evaporator downstream temperature T' _INT is set to 3°C, and the process proceeds to step 94.
At 95, transition control from demist control to normal control is performed.

In the next step 98, the evaporator downstream temperature _TINT is determined, and if it is below a predetermined value (side B), the process proceeds to step 99 and the variable capacity compressor is turned off, and if it is above a predetermined value (side A). Proceed to step 100 to set the target evaporator downstream temperature.
T′ _INT is calculated. That is, T' _INT is determined from a predetermined characteristic pattern based on the target blowout temperature X _M , which is a heat load factor. Then, the process proceeds to step 101, where the discharge capacity of the variable capacity compressor 10 is controlled so that _{T_INT} approaches _{T'_INT} , and the process proceeds to end step 102, where the control ends.

Although this embodiment shows an example in which refrigerant temperature is used to detect the refrigerant capacity state, refrigerant pressure may be used instead.

(Effects of the Invention) As explained above, according to the present invention, the degree of cooling of the evaporator is changed depending on the outside air temperature, and when the outside air temperature is higher than a predetermined temperature, the temperature on the downstream side of the evaporator is changed to the predetermined temperature. Since the refrigerant temperature of the evaporator is used in the following cases, the degree of cooling can be accurately detected from when the heat load on the evaporator is relatively high to low (below the freezing temperature).

In addition, by taking advantage of the feature of the external variable capacity compressor, which can gradually cool the compressor to below freezing temperature through small capacity operation, it is possible to improve the demisting ability below freezing temperature.

Furthermore, the mode sensor and refrigerant temperature sensor double protect the compressor from freezing.
This has the effect of improving the reliability of freeze protection.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a block diagram showing an automotive air conditioning control device according to an embodiment of the invention, and Fig. 3 shows the capacity of the variable capacity compressor using the microcomputer used in the above. a flowchart showing the control routine;
FIG. 4 is a sectional view of the variable capacity compressor. 7...Blower, 8...Evaporator, 10...
Variable capacity compressor, 17... Evaporator downstream temperature sensor, 26... Refrigerant temperature sensor, 27
... Microcomputer, 31 ... Outside air temperature sensor, 200 ... Outside air temperature determination means, 300 ...
Detection switching means, 400... Capacity control means.

Claims (1)

[Claims] 1. An evaporator disposed in an air conditioning duct to cool the air sucked in by a blower; an external variable capacity compressor that forms part of a refrigeration cycle together with the evaporator and whose capacity is externally controlled; refrigerant capacity state detection means for detecting the refrigerant temperature or refrigerant pressure of the evaporator; evaporator downstream temperature detection means for detecting the temperature of the air immediately after passing through the evaporator; and determining the outside air temperature detected by the outside air temperature sensor. an outside air temperature determining means for determining the temperature of the outside air, and when the determination result of the outside air temperature determining means is above a predetermined temperature, the detected value by the evaporator downstream temperature detecting means is used, and when the determination result is below the predetermined temperature, the detected value by the refrigerant capacity state detecting means is sent to the evaporator. An air conditioner for an automobile, comprising: a detection switching means for outputting a cooling degree; and a capacity control means for appropriately controlling the capacity of the external variable capacity compressor based on the evaporator cooling degree input from the detection switching means. Control device.