JPH0516656A - Fault diagnostic unit for vehicle air conditioner - Google Patents

Abstract

PURPOSE:To eliminate the danger of an evaporator being frozen during a diagnosis so as to accurately diagnose faults in an externally controlled variable capacity compressor for use in the refrigerating cycle of a vehicle air conditioner. CONSTITUTION:External control signals for a variable capacity compressor are varied in sequence according to a predetermined test pattern, and in one of the tests of the test pattern at which the discharging ability of the variable capacity compressor is increased, the time required for the signal level of the external control signals to become constant is regulated and the state of the compressor in which its discharging ability is high is varied after a predetermined time elapses, so as to reduce the feed rate of a refrigerant before freezing of the evaporator and also to prevent the discharging ability of the compressor from being changed before blowout temperature is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This device relates to a device for diagnosing a failure of a vehicle air conditioner, and more particularly to a device using a variable capacity type compressor in a cooling cycle.

[0002]

2. Description of the Related Art In recent years, variable-capacity compressors have become popular as compressors used in a cooling cycle of an air conditioner for automobiles. Even in the diagnosis of an air conditioner for a vehicle, the discharge capacity of the compressor is controlled by an external control signal. It is necessary to examine whether or not the discharge capacity changes according to the above. Therefore, the present applicant has previously applied for a failure diagnosis device that can check the change and the discharge volume (Japanese Patent Laid-Open No. 2-3191).
2).

This is to manually switch the control signal to the variable capacity member of the compressor together with the control signals to the other air conditioners based on a predetermined test pattern prepared in advance, and to blow the air conditioner for each test. The operation state is confirmed by experiencing the air volume and temperature of the air coming out of the outlet or by listening to the operation sound.

[0004]

However, in diagnosing the operation of the compressor, when the discharge capacity of the compressor is increased, if the test pattern is not switched or the switching is delayed, there is a risk of freezing of the evaporator. ..

In order to avoid this danger, the manual switching of the test pattern may be carried out promptly, but if it is switched to an early point, the discharge capacity of the compressor will change before the blowing temperature changes, and the operating state will be accurate. There is a risk that the confirmation may not be possible, and the switching timing was difficult.

In view of the above, the present invention has been made to solve the above-mentioned problems and is intended for a vehicle in which proper switching timing is ensured to eliminate the risk of freezing of the evaporator during diagnosis and to make accurate diagnosis. It is an object to provide a failure diagnosis device for an air conditioner.

[0007]

SUMMARY OF THE INVENTION The gist of the present invention is, therefore, a variable capacity compressor for varying the discharge capacity by an external control signal to adjust the refrigerant supply amount to an evaporator arranged in an air conditioning duct. In a failure diagnosis device for a vehicle air conditioner including: a signal variable means for sequentially changing an external control signal to the variable capacity compressor based on a predetermined test pattern; and a discharge of the variable capacity compressor in the test pattern. A fault diagnostic device for a vehicle air conditioner, comprising: a signal level control unit that regulates a time period during which a signal level of the external control signal is constant in a test with high capacity.

[0008]

Therefore, when the external control signal is sequentially switched on the basis of the test pattern and the test is shifted to the one in which the discharge capacity of the variable capacity compressor is increased, the amount of refrigerant supplied to the evaporator is increased, and there is a fear of freezing. ,
Since the signal level control means regulates the time for keeping the signal level of the external control signal constant, the state in which the discharge capacity of the compressor is large is changed after the predetermined time continues even during diagnosis, and the refrigerant supply amount to the evaporator is changed. It can be suppressed before freezing.

Further, if the control means appropriately adjusts the constant time of the signal level, there is no premature switching such that the discharge capacity of the compressor changes before the blowout temperature changes, and the above-mentioned object is achieved. Is what you can do.

[0010]

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

In FIG. 1, the vehicle air conditioner is provided with an intake switching device 2 on the most upstream side of an air conditioning duct 1.
The intake switching device 2 includes an inside air inlet 3 and an outside air inlet 4
The inside / outside air switching door 5 is arranged in a portion where is divided, and the inside / outside air switching door 5 is operated by the actuator 6 to select the air introduced into the air conditioning duct 1 between the inside air and the outside air,
A desired inhalation mode is obtained.

The blower 7 sucks air into the air-conditioning duct 1 and blows it to the downstream side, 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 amount of air passing through the heater core 9 and air bypassing the heater core 9 is adjusted by adjusting the opening of the air-mix door 10 with the actuator 11. Is changed so that the temperature of the blown air is 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 and opens into a passenger compartment 15. Mode doors 16a, 16b and 16c are provided at the divided portions. Is provided, and the mode doors 16a, 16b, 16c are connected to the actuator 17
The desired blowout mode can be obtained by operating in.

The evaporator 8 is a compressor 1
8, the condenser 19, the liquid tank 20, and the expansion valve 21 constitute a cooling cycle.

The compressor 18, as shown in FIG.
For example, a wobble plate type drive shaft 24 connected to the engine 22 via an electromagnetic clutch 23 is inserted into a compressor body 25, and a wobble plate 26 is connected to the drive shaft 24 via a hinge ball 27. There is. The wobble plate 26 is swingably supported by a crank chamber 28 formed in the compressor body 25 with a hinge ball 27 as a fulcrum, and a piston 29 connected to the wobble plate 26 has a swing angle. It reciprocates in the cylinder bore 30 with a stroke corresponding to.
The compressor 18 is provided with a pressure control valve 31 in the crank chamber 28 as desired.
Is a valve body 33 that adjusts the communication state between the crank chamber 28 and the suction chamber 32 that communicates with the suction side, a pressure responsive member 34 that moves the valve body 33 according to the pressure in the suction chamber 32, and the valve body 33. Between the piston 29 and the cylinder bore 30 by controlling the energization amount (I _SOL ) to the electromagnetic coil 35 from the outside by having a solenoid 36 that moves according to the energization amount (I _SOL ) to the electromagnetic coil 35. The amount of blow-by gas that leaks into the crank chamber 28 from the suction side is adjusted.

Therefore, a capacity varying device 37 for changing the capacity of the compressor 18 from the pressure control valve 31 is constructed.
When the amount of current (I _SOL ) flowing in the electromagnetic coil 35 rises and the magnetic force of the solenoid 36 rises, a force in the direction of restricting the communication between the crank chamber 28 and the suction chamber 32 moves to the valve body 33, and suction from the crank chamber 28 occurs. The amount of blow-by gas that escapes to the chamber 32 is reduced. For this reason, 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 is rotated in a direction to reduce the swing angle, and the stroke of the piston 29, that is, Compressor capacity is reduced.

On the contrary, the amount of current (I
_(SOL ) decreases and the magnetic force of the solenoid 36 decreases, the throttle between the crank chamber 28 and the suction chamber 32 becomes loose, and the amount of blow-by gas that escapes from the crank chamber 28 to the suction chamber 32 increases. For this reason, the pressure in the crank chamber 28 decreases and the force acting on the back surface of the piston 29 decreases, so that the wobble plate 26 is rotated in the direction of increasing the swing angle, and the stroke of the piston 29 increases. The capacity of the compressor will increase.

The variable capacity device 37 not only controls the amount of blow-by gas returned to the suction side by the pressure control valve, but also changes the number of cylinders used by the compressor, and connects the compressor and the engine 22. It is possible to change the capacity substantially, such as changing the pulley ratio of the belt transmission device or changing the number of effective vanes in the vane type compressor. Also,
In this embodiment, I _SOL can be varied within a range from 0.1 A which maximizes the discharge capacity to 0.6 A which minimizes it.

The actuators 6, 11, 1
7, the motor of the blower 7, the electromagnetic clutch 23 of the compressor 18, and the variable capacity device 37 are respectively driven by a drive circuit 40.
It is controlled based on the output signal from the microcomputer 41 via a to 40f.

The microcomputer 41 includes a central processing unit (CPU), a read-only memory (ROM, not shown).
), Random access memory (RAM), I / O port
(I / O), a crystal oscillator 42 for generating a reference pulse, etc., which are known per se,
1 is a vehicle interior temperature sensor 43 that detects the temperature in the vehicle interior.
The output signals from the above are selected via the multiplexer 44, converted into digital signals via the A / D converter 45, and input.

An output signal from the operation panel 46 is input to the microcomputer 41. The operation panel 46 includes a microcomputer 41 and a display circuit 4.
The display unit 48 has a display unit 48 connected via the display unit 4.
8, the blower speed, the blowing mode, the set temperature, the outside air temperature, etc. are displayed. In addition, an A / C switch 49 for operating the compressor 18 in a normal state and an ECON switch 50 for economically operating the compressor 18 are provided. By turning on any of these switches, each air conditioner starts operating in the automatic control mode, The operating states of these are displayed on the display unit 48.

Further, on the operation panel 46, the blower 7, the compressor 18, etc. are stopped and the display section 48 is turned off.
FF switch 51, diff switch 52 for setting blowout mode to defrost mode, and intake mode for introducing inside air (REC)
Intake switch 5 to switch between air and outside air introduction (FRESH)
3. The AMB switch 54 for displaying the outside air temperature is provided at the temperature display portion 58 of the display section 48, and the up / down switches 55a, 5 for setting the target temperature in the vehicle interior in addition to the above.
5b, a MODE switch 56 for switching the blowout mode in the order of vent, bilevel, and heat, and a blower switch 57 for setting the rotation speed of the blower. The set temperature is normally displayed at the temperature display portion 58 of the display unit 48, and the up / down switches 55a, 5
This display temperature can be changed by the operation of 5b, and the blowout mode display portion of the display unit 48,
The contents set by the operation of the MODE switch 56 and the blower switch 57 are also displayed on the blower speed display portion (not shown).

In this embodiment, the blowout mode can be selected from vent, bi-level, differential foot 1, differential foot 2 (the amount of flow at the foot is larger than differential foot 1) and defrost mode, and the intake mode is REC (internal air. Introduction), FRESH (outside air introduction), 20% FRESH (20% outside air introduction, 80% inside air introduction) can be selected, and the blower speed is low speed (1 step), medium low speed (2 steps), medium high speed (3
It is possible to select either high speed (4 steps) or high speed (4 steps).

FIG. 3 shows an example of control by the microcomputer 41 described above. The microcomputer 41 turns on (OFF) an ignition switch (IGN SW).
→ After turning on, turn off the switch for a predetermined time t ₁ (for example, 5
Press for more than _sec ) to enter failure diagnosis mode.

The failure diagnosis mode has a plurality of diagnosis steps having different diagnosis contents. When the failure diagnosis mode is entered, the diagnosis step 1 is executed and the up switch 55 is operated.
Each time a is pressed, the next diagnostic step 2, 3, 4, ... Is executed. Also, the down switch 55b
Operation returns to the previous diagnostic step, and in each diagnostic step, when the switch 49 or 50 for switching to the AUTO control mode is pressed, or when the ignition switch is turned from ON to OFF, the failure diagnosis is performed. It is supposed to end.

For example, in the diagnostic step 4, the compressor 1
If the failure diagnosis program for the air conditioner including 8 is built in, the program can be executed by pressing the up switch 55a three times at the time of entering the failure diagnosis mode.

In FIG. 4, the concrete contents of this diagnostic step 4 are shown as a flow chart, and this diagnostic step 4 starts execution from step 70, and step 72
To set the air conditioner and the like to the test status of diagnostic code "41". Figure 6 shows the diagnostic code and the setting status of the air conditioning equipment.
Corresponding as shown in the table of (a), for example, the state of the diagnostic code "41" indicates that the code number "41" is displayed at the temperature display portion 58 of the display unit 48 and the blowout mode is vented. Mode, inhalation mode to inside air inhalation (REC),
The air-mix door position is set to a position where the heating capacity is minimized, that is, the full-cool position shown by the chain double-dashed line in FIG. 1, the rotation speed of the blower is set low, and the supply current I _SOL to the pressure control valve 31 of the compressor 18 is set to 0. The state set to 1A.

After the above setting, step 74
5, the subroutine (SUBI) shown in FIG. 5 is executed, and the up switch 55a is executed in this subroutine.
Is operated, the down switch 55b is operated, and the presence or absence of operation of the switches 49, 50 or the ignition switch for setting the automatic control mode is determined (step 74a).
To 74c), when the up switch 55a is pressed, the process proceeds to the next diagnostic step 5, and when the down switch 55b is pressed, to the previous diagnostic step 3 (steps 74d to 74e), the automatic control mode If is selected, or if the ignition switch is turned off, the diagnosis ends (step 74f).

After this subroutine, in step 76, it is judged whether or not the AMB switch 54 is pressed. If the AMB switch 54 is not pressed, the process returns to step 72 and the state of the diagnostic code "41" is judged. Maintained,
If the AMB switch 54 has been pressed, the routine proceeds to step 78, where the state of the diagnostic code 42 is set. Thereafter, each time the AMB switch 54 is pressed, the diagnostic code is updated, the code number of the temperature display portion 58 is also changed accordingly, and after the last diagnostic code (for example, "47"), "41" is again displayed.
To return to.

A predetermined test pattern is constituted by these diagnostic codes "41" to "47", and the diagnostic code "42" supplies a current (I
_SOL ) is set to a minimum discharge capacity of 0.6 A, and the blowout mode, the suction mode, the air-mix door position, and the fan speed are all set to the same state as the diagnostic code “41”.

In the diagnostic code "43", I _SOL is set to 0.3 A, which is a predetermined intermediate capacity, and the diagnostic code "4" is set.
The blowout mode was changed from VENT to BI / L and the blower speed was changed from low speed to medium to high speed for the condition of 2 ”, and in the diagnostic code“ 44 ”, the blowout mode was changed from REC to 20% FRESH for“ 43 ”. Change the air mix door from FULL COOL to FULL HOT, and change the blower speed from medium to high speed.

In the diagnostic code "45", the blowing mode is changed from BI / L to DEF / FOOT1 and the suction mode is changed from 20% FRESH to FRESH for "44", and I _{SOL is set} to 0.6 A, With the diagnostic code "46", the blowing mode is set to DFE / FOOT2 from the state of "45", and the compressor 18
To stop.

Further, in the diagnostic code "47", "4"
6 ”, the blowout mode is set to DEF, the blower speed is set to high, and the external control signal I _SOL of the compressor is set to 0.3.
A.

Then, in the test "41" in which the discharge capacity of the compressor is maximum (I _SOL is 0.1 A), as shown in FIG. 6 (b), the discharge capacity after a predetermined time (T ₁ ) has elapsed. Is set to the minimum (I _SOL is 0.6 A), this state is maintained for a predetermined time (T ₂ ), and then the discharge volume is set to the maximum (I _SOL is 0.1 A). After that, I _SOL is set until the AMB switch is pressed. The constant state is changed at the above intervals.

Here, it is desirable to select the time T _{1 that} is sufficient for the evaporator not to freeze and the outlet temperature to change after the compressor is operated at the maximum discharge capacity, for example, 5 minutes. The place is good.

When the output of I _SOL that maximizes the discharge capacity is displayed, the A / C display is lit on the display unit 48, and when the output of I _SOL that minimizes the discharge capacity is displayed, the ECON is displayed on the display unit 48.
You may make it light a display.

Therefore, in the test "41" in which the discharge capacity of the compressor 18 is large, the evaporator 8 may freeze, but the maximum discharge capacity is not maintained and the predetermined interval is not maintained. The freezing can be prevented in advance because the discharge capacity is alternately switched to the minimum state.

Further, in this embodiment, in the test of "41", the discharge capacity of the compressor 18 is changed from the maximum to the minimum without pressing the AMB switch 54.
The test of the diagnostic code “41” substantially includes the test of “42”, and thus the test of “42” can be omitted. In this case, it is desirable to set T ₂ to about 5 minutes in order to secure a sufficient fluctuation of the blowout temperature, whereby the discharge capacity of the compressor is switched from the maximum to the minimum, or vice versa. The change in temperature can be easily discerned by the user's feeling, and the normal or abnormal state of the capacity variable mechanism can be accurately confirmed.

[0039]

As described above, according to the present invention,
In the test for increasing the discharge capacity of the variable capacity compressor, the time for keeping the signal level of the external control signal constant is regulated, and the state in which the discharge capacity of the compressor is large is changed after a predetermined time has passed. It is possible to prevent the evaporator from freezing.

Further, since the change from the state with a large discharge capacity is performed after a lapse of a predetermined time, there is a problem that the discharge capacity of the compressor changes before the change of the blowout temperature by appropriately adjusting the change timing. It is possible to prevent this, and to ensure an appropriate switching timing and perform accurate diagnosis.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a variable capacity compressor used in the vehicle air conditioner according to FIG.

FIG. 3 is an explanatory diagram showing an outline of an operation procedure in a failure diagnosis mode.

FIG. 4 is a flowchart showing the specific contents of diagnostic step 4 in FIG.

5 is a flowchart showing a specific example of a subroutine used in the flowchart of FIG.

FIG. 6 (a) is a list showing diagnostic codes and their contents, and FIG. 6 (b) is a characteristic diagram showing changes in the discharge capacity of the compressor.

[Explanation of symbols]

 1 Air conditioning duct 8 Evaporator 18 Variable capacity compressor

Claims (1)

Claim: What is claimed is: 1. A failure diagnosis of a vehicle air conditioner equipped with a variable capacity compressor, wherein the discharge capacity is varied by an external control signal to adjust the refrigerant supply amount to an evaporator disposed in an air conditioning duct. In the apparatus, a signal varying means for sequentially changing an external control signal to the variable displacement compressor based on a predetermined test pattern, and the external control in a test for increasing the discharge capacity of the variable displacement compressor in the test pattern. A fault diagnosis device for a vehicle air conditioner, comprising: a signal level control unit that regulates a time when a signal level of a signal becomes constant.