JP2799764B2 - Automotive air conditioners - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a failure diagnosis of a variable condenser capacity device provided in a condenser in an air conditioner for a vehicle.

[Conventional technology]

As described in JP-A-2-31912, a conventional device switches a control valve coil supply current which is an output to a variable capacity device of a compressor by operating a switch on an operation panel to change a cooling capacity. It has a failure diagnosis function for the variable capacity device, for example, by judging from a change in the temperature of the blown air.

Further, as described in JP-A-2-24220, a bypass line having a pressure regulating valve which opens when the refrigerant pressure in the condenser falls below a predetermined value is provided in the condenser line, and the condensing pressure is set to a constant value. I try to keep it above.

[Problems to be solved by the invention]

However, in the technique described in Japanese Patent Application Laid-Open No. Hei 2-24220, the pressure regulating valve is a mechanical type, and no consideration is given to failure diagnosis.

Further, in the technique described in Japanese Patent Application Laid-Open No. Hei 2-31912, no consideration is given to the case where the cooling cycle control device is only the variable capacity device, and the condensing capacity variable device is added.

It is an object of the present invention to provide an air conditioner for a vehicle which can perform a failure diagnosis of a cooling cycle having a plurality of control devices including the above-mentioned variable condensing capacity device.

[Means for solving the problem]

In order to achieve the above object, a first invention of the present invention is to provide a cooling cycle having a condenser having a variable condenser capacity and a compressor having a variable discharge capacity, and a cooling cycle having the same. In a vehicle air conditioner, comprising: a diagnostic function instructing unit that outputs a control signal in a predetermined pattern; and a diagnostic control unit that controls the discharge capacity variable device when the diagnostic function is selected by the instruction unit. The diagnostic control means controls the condensation capacity variable device in accordance with the output of the instruction means, and, when instructing the condensation capacity variable device to reduce the condensation capacity, sets a small capacity with respect to the discharge capacity variable device. It is a means for outputting an instruction on the side.

According to a second aspect of the present invention, there is provided an air conditioner for a vehicle equipped with a cooling cycle having a condenser having a variable condenser capacity with respect to the heat load of the vehicle, wherein the heat load of the vehicle is detected. Heat load detecting means, indicating means for a diagnostic function for outputting a control signal to the condensing capacity variable device in a predetermined pattern, and diagnostics for controlling the condensing capacity variable device when the diagnostic function is selected by the indicating means Control means, wherein the diagnostic control means has means for prohibiting output of a capacity reduction control signal to the condensation capacity variable device when the heat load detection means detects a heat load equal to or greater than a predetermined value. It is a feature.

A third invention of the present invention is directed to a cooling cycle having a condenser having a variable condenser capacity and a compressor having a variable discharge capacity for a heat load of an automobile, and a variable discharge capacity apparatus. And a diagnostic control means for controlling the discharge capacity variable device when the diagnostic function is selected by the instruction means. A heat load detecting means for detecting a heat load of the vehicle, wherein the control means for diagnosis controls the variable condensation device in accordance with an output of the instruction means, and the heat load detecting means is equal to or less than a predetermined value. And a means for outputting a capacity reduction control signal to the condensing capacity variable device when the heat load is detected.

According to a fourth aspect of the present invention, in the second or third aspect, the heat load detecting means detects a temperature of outside air.

[Action]

According to the first aspect, the determination as to whether or not the variable condenser capacity device of the condenser functions correctly is performed when the condenser capacity is reduced.
This can be determined by an increase in the indicated value of a pressure gauge provided in the discharge pipe of the compressor. At this time, since the discharge capacity variable device is instructed to the small capacity side, the condensation pressure is hardly increased, and even in an environment where the heat load is high, the failure diagnosis of the condensation capacity variable device is performed without operating the high pressure protection switch. be able to.

Further, in the second invention, when the heat load detecting means detects a predetermined value or more, the means for inhibiting the output of the capacity reduction control signal to the condensing capacity variable device is provided. The capacity of the vessel can be reduced to prevent the condensation pressure from becoming too high and damaging the cooling cycle components.

Further, in the third invention, when the heat load detecting means detects a predetermined value or less, a means for outputting a capacity reduction control signal to the condensing capacity variable device is provided, so that the discharge pressure required for operation of the discharge capacity variable device is provided. However, a high value can be obtained even with a low heat load, and a failure diagnosis of the discharge capacity variable device can be performed.

Further, in the fourth aspect, since the heat load detecting means is the outside air temperature detecting means, the outside air temperature detecting means provided for air conditioning can be used.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a configuration diagram of an automotive air conditioner according to one embodiment of the present invention. The air conditioner sucks air with an intake blower unit 1 and a cooling unit 2
After the air is cooled by the heater unit 3 and the air is appropriately heated by the heater unit 3, the air is blown into the vehicle compartment 4.

The intake blower unit 1 includes an inside air suction port 5,
It comprises an intake door 7 for switching between an outside air inlet 6 and a blower 8 for sending air. There are three states of intake of air depending on the position of the intake door 7, namely, "outside air", "inside air", and "inside / outside air" as shown.

The cooling unit 2 includes an evaporator 9 serving as an evaporator, an expansion valve 10, and an air temperature sensor 11 provided downstream of the evaporator 9. In addition, the evaporator 9
The expansion valve 10, the compressor 12 as a compressor, the condenser 13 as a condenser, and the receiver 14 constitute a known cooling cycle.

The compressor 12 operates by using an automobile engine 16 connected by a belt via a magnet clutch 15 as a power source, and controls a control valve 17 and a coil 18 serving as a discharge capacity variable unit.
Built-in. The coil 18 can set the minimum value of the suction refrigerant pressure of the compressor 12 by the supplied current,
17 controls the pressure so that the suction refrigerant pressure does not drop below a set value.

The condenser 13 is a motorized version of a condenser condensation variable device known in Japanese Patent Application Laid-Open No. 2-24220.
A conduit 19 is provided in the middle of the condenser 13 to bypass the inlet, and in the middle of the conduit 19, there is provided an electromagnetic valve 20 which is a condensing capacity variable means that opens when a voltage is applied. When the solenoid valve 20 is opened, the conduit 19 passes through the inlet of the condenser 13.
Almost no refrigerant flows between the connecting portions, and the substantial area of the condenser 12 is reduced, and condensing capacity is reduced.

The heater unit 3 is provided with a cooling water (temperature, about
80 ° C.) and a heater 21
Air mix door 22 to control the proportion of air passing through
And two mode doors 23a and 23b for switching the outlet into the vehicle cabin. Depending on the position of the mode doors 23a and 23b, the outlet into the vehicle cabin is shown as a "diff / foot" blown out from the foot opening 24 and the differential opening 25, a "diff" blown out only from the differential opening 25, and only from the vent opening 26. It switches to “Bent” which blows out and “B / L” which blows out from the vent opening 26 and the foot opening 24.

The air conditioner operates in response to an instruction from the electronic control circuit 27. The electronic control circuit 27 has a built-in microcomputer 28 that performs calculations and judgments for performing control. The microcomputer 28 of this embodiment includes a central control unit, a read-only memory (hereinafter referred to as ROM) for storing processing procedures (programs and constants), a random access memory for storing data, and an on / off input / output terminal (hereinafter referred to as I / O terminal). / O), analog-to-digital conversion input terminal (hereinafter A / D), pulse output terminal of arbitrary width (hereinafter referred to as PWM) and so on.

The microcomputer 28 is connected to a crystal oscillator 29 having a frequency of 1 MHz which constitutes an oscillator for determining a basic cycle. The power supply is a battery (not shown).

Next, input and output of electric signals to and from the microcomputer 28 will be described for each device.

The output signals of the air temperature sensor 11 downstream of the evaporator, the air temperature sensor 30 of the passenger compartment 4, and the air temperature sensor 31 of the outside air are
The signal is taken into the A / D of the microcomputer 28 via the multiplexer circuit 32.

The intake door 7, the air mix door 22, and the mode doors 23a and 23b are driven by motors 33a, 33b and 33c, respectively, and drive signals are output via a motor drive IC.

The blower 8 is driven by a motor 35, and a voltage applied to the motor 35 is supplied to a power transistor 37 through a constant voltage circuit 36.
Is controlled by

The electromagnetic valve 20 is turned on and off by a relay 39 that is driven via a transistor 38. When the solenoid valve 20 is turned on, the refrigerant flows from the bypass pipe, and the condensing capacity is reduced.

The magnet clutch 15 is turned on and off by a relay 40 driven through a transistor 38. Between the said relay 40 and the magnet clutch 15, there are high and low pressure switch provided in the receiver 14, the refrigerant pressure is 1.1 kgf / cm ² G or less, or becomes more than 27 kgf / cm ² G, the magnetic clutch 14 Turn off.

The coil 18 is supplied with a current according to the set value of the evaporation pressure of the refrigerant via the constant current circuit 41.

The operation panel 42 performs the status display and setting of the air conditioner. The switch signal on the operation panel 42 enters the I / O of the microcomputer 28, and the display unit is controlled through the display drive circuit 43. Is done.

Next, the functions of the switches and the display unit on the operation panel 42 will be described.

The “AUTO” switch 44 instructs automatic control operation of the air conditioner. The "Diff" switch 45 instructs the "Diff" fixation of the air blowing to the cabin. The “REC” switch 46
Instructs the "inside air" fixation of air suction. The “ECON” switch 47 turns off the magnet clutch 15 and instructs to stop the cooling cycle. The “OFF” switch 48 instructs to stop the air conditioner. The "△" switch 49 instructs an increase in the vehicle interior air temperature set value, and the "▽" switch 50 instructs a decrease in the vehicle interior air temperature set value.

The “SET” display 51 displays the set value of the vehicle interior air temperature, and the “AMB” display 52 displays the vehicle interior air temperature.

2 to 4, the programs stored in the ROM of the microcomputer 38 will be described. Note that the numbers in the figure indicate step numbers.

The microcomputer 28 executes the processing from step 100 in FIG. 2 by turning on the ignition switch of the automobile. In step 100, "normal control" for controlling the air conditioner in a normal state is executed.

The control of the electromagnetic valve 20 in “normal control” is off when the outside air temperature ≧ Ta1. Here, Ta1 is the first predetermined value, which is the predetermined value of the second invention. Also, outside air temperature <Ta
In step 1, the process is performed based on the relationship between the command current of the coil 18 and the target temperature and the evaporator downstream air temperature. That is, when the energizing current of the coil 18 is the minimum capacity instruction, and the evaporator downstream air temperature is equal to or lower than the target value, the electromagnetic valve 20 is set to increase the condensation pressure so that the evaporator downstream air temperature increases. Turn on to reduce condensation capacity. On the other hand, when the energizing current of the coil 18 indicates the maximum capacity and the downstream air temperature of the evaporator is equal to or higher than the target value, the electromagnetic valve 20 is set to lower the condensation pressure so that the downstream air temperature of the evaporator decreases. Turn off to increase condensation capacity.

In step 101, it is determined whether the "AUTO" switch 44 has been pressed. If NO, the process returns to step 100. YES
In step 102, it is determined in step 102 whether the "OFF" switch 48 has been pressed for 5 seconds or more. If no, step 100
Return to

In the case of YES, the process proceeds to step 103 and enters into the failure diagnosis control. That is, the failure diagnosis control is performed by the "AUTO" switch 44 and the "OFF" switch in the same manner as in the method described on pages E-45 to E-48 of Service Report No. 628 (July 1989) issued by Nissan Motor Co., Ltd. "Select by pressing switch 48 simultaneously for 5 seconds or more.

In step 103, the item of diagnosis is set to "input", and in step 104, "failure diagnosis control" described later is executed.
In step 105, it is determined whether only the "OFF" switch 48 is pressed and an instruction to return to "normal control" is given. If YES, return to step 100; if NO, step 103
Return to

The "failure diagnosis control" of step 104 will be described with reference to FIG. In step 110, it is determined whether only the "AUTO" switch 44 has been pressed and an instruction to switch an item has been issued. YES
In the case of, the diagnostic item is switched in step 111.
In step 112, the output signals of the air temperature sensors 11, 30, 31 are input.

In step 113, it is determined whether the diagnosis item is “input”. If YES, a fault diagnosis of the input system is performed in step 114.

In step 115, it is determined whether the diagnosis item is "output". In the case of YES, a failure diagnosis of the output system described later is performed in step 116.

In step 117, it is determined whether the item is “adjustment”. If YES, the target value is adjusted in step 118.

In step 119, it is determined that the item is "failure display", the display of the failure content is executed, and the failure diagnosis control ends.

The "output diagnosis" of step 116 will be described with reference to FIG. In step 120, it is determined whether the "△" switch 49 has been pressed. In the case of YES, in step 121, the output pattern code described later is switched.

In step 122, it is determined whether the “▽” switch 50 has been pressed. If YES, the output pattern code described later is switched in step 123.

In step 124, according to the code of the output pattern,
A signal is output to the output system by the combination of FIG. 5, and the “output diagnosis” is completed. The code of the output pattern is
The “AMB” display 52 on the operation panel 42 is displayed numerically and “SE
In the "T" display 51, "30" indicating "output diagnosis" is displayed.

Next, FIG. 5 will be described. When the outside air temperature detected by the air temperature sensor 28 is lower than Ta2, the electromagnetic valve 18, which is a variable condenser device, is turned on. In that case, the last digit of the code is set to "1", Inform Here, Ta2 is a second predetermined value lower than Ta1, which is the predetermined value of the third invention.

The failure diagnosis of the coil 18 is performed when the code “60” (“61”), the code “70” (“71”), and the code “80” (“81”) are used. ], The current flowing through the coil 18 is switched. As in the third invention, with a low heat load,
When the electromagnetic valve 20 is turned on, the condensing capacity is reduced, and the pressure of the refrigerant discharged from the compressor 12 is increased, so that the control range of the evaporation pressure is widened. As a result, the temperature of the air blown into the vehicle compartment changes greatly, and the operation of the coil 18 is caught by the change in the sense of warmth, so that the failure inspection operator can easily diagnose the failure of the coil 17.

Diagnosis of the failure of the electromagnetic valve 20 is performed by providing a pressure gauge 53 on the discharge side of the compressor 12 and visually indicating the indicated value by a failure inspection operator. That is, the discharge pressure of the compressor 12 changes as shown in FIG. Code “80” (“81”), Code “91” (“90”)
[Figures in parentheses are for outside air temperature <Ta2. ] With solenoid valve 2
When 0 is turned on and off and the indicated value of the pressure gauge 53 changes, it is determined that the electromagnetic valve 20 is normal. At that time,
As in the first invention, a coil that is a variable discharge capacity device
The current supplied to the compressor 18 is 1.2 A, that is, the discharge capacity of the compressor 12 is instructed to the smaller capacity side. Therefore, the condensing pressure is unlikely to increase, and failure diagnosis of the electromagnetic valve 20 can be performed without operating the high-pressure protection switch provided on the receiver 14.

Furthermore, the code “91” (“90”) [() indicates the case where the outside air temperature <Ta2. In the case of [2], the ON of the electromagnetic valve 18 is prohibited when the outside air temperature is equal to or more than Ta2 as in the second invention, so that the condensation pressure becomes too high and the cooling cycle parts can be prevented from being damaged.

In the present embodiment, the outside air temperature sensor is used as the heat load detecting means, but a refrigerant pressure sensor discharged from the compressor may be used. Further, in the system provided with the discharged refrigerant pressure sensor, a detection value of the discharged refrigerant pressure sensor may be used instead of the pressure gauge 53.

According to the present embodiment, it is possible to prevent the cooling cycle component from being damaged due to an erroneous operation by the failure inspection operator, and further, it is possible to perform the failure inspection at a wide range of outside air temperature.

〔The invention's effect〕

As described above, according to the present invention, in the first invention, since the compressor is operated on the small capacity side, the condensing pressure becomes low, and the electromagnetic valve which is the condensing capacity variable device fails until the environment where the outside air temperature is high. It has the effect of making a diagnosis.

In the second invention, when the heat load is high, the failure diagnosis of the electromagnetic valve is prohibited, so that there is an effect that the cooling cycle components can be prevented from being damaged by the high-pressure refrigerant.

In the third invention, when the heat load is low, the current flowing through the coil, which is the variable displacement capacity device, is set to the small capacity side. Thus, there is an effect that a failure diagnosis of the electromagnetic valve can be performed.

According to the fourth aspect, there is an effect that an outside air temperature sensor used for air conditioning can be used as a means for determining a heat load.

[Brief description of the drawings]

FIG. 1 is a block diagram of an air conditioner for a vehicle according to an embodiment of the present invention, FIGS. 2 to 4 are flowcharts of programs stored in a microcomputer of FIG. 1, and FIG. FIG. 6 is a view showing a change in the discharge pressure of the compressor when the electromagnetic valve is turned on or off. 12 Compressor (Compressor), 13 Condenser (Condenser), 18 Coil (Discharge capacity variable device), 20 Electromagnetic valve (Condensable capacity variable device), 28 Microcomputer (Diagnostic control 31) Air temperature sensor (heat load detecting means, outside air temperature detecting means), 44 "AUTO" switch (indicating means), 48 ... "OFF" switch (indicating means).

Claims (4)

(57) [Claims] A cooling cycle having a condenser having a variable condenser capacity and a compressor having a variable discharge capacity;
Diagnostic means for outputting a control signal to the discharge capacity variable device in a predetermined pattern; and diagnostic control means for controlling the discharge capacity variable device when the diagnostic function is selected by the instruction means. In the air conditioner for an automobile, the control unit for diagnosis controls the variable condensation device in accordance with an output of the instruction unit, and the discharge capacity is controlled when the variable condensation device is instructed to reduce the condensation capacity. An air conditioner for an automobile, which is a means for outputting an instruction of a small capacity to a variable device. 2. An air conditioner for a vehicle having a cooling cycle having a condenser with a variable condenser capacity with respect to a heat load of the vehicle, wherein a heat load detecting means for detecting a heat load of the vehicle; A diagnostic function instructing means for outputting a control signal to the condensing capability variable device in a predetermined pattern; and a diagnostic control means for controlling the condensing capability variable device when the diagnostic function is selected by the instruction means, The diagnostic control means includes means for prohibiting output of a capacity reduction control signal to the condensing capacity variable device when the heat load detecting means detects a heat load equal to or greater than a predetermined value. Harmony equipment. 3. A cooling cycle having a condenser having a variable condenser capacity and a compressor having a variable displacement capacity for a heat load of an automobile, and a control signal to the variable displacement capacity device is provided in a predetermined pattern. Means for instructing a diagnostic function to be output by
A diagnostic control means for controlling the discharge capacity variable device when a diagnostic function is selected by the instruction means, wherein the thermal load detecting means for detecting a thermal load of the vehicle is provided,
The diagnostic control means controls the condensation capacity variable device in accordance with the output of the instructing means, and when the heat load detection means detects a heat load of a predetermined value or less, the control section controls the condensation capacity variable device. An air conditioner for a vehicle, comprising means for outputting a capacity reduction control signal. 4. The air conditioner for a vehicle according to claim 2, wherein said heat load detecting means detects a temperature of outside air.