JPH06458B2 - Failure diagnosis method for automobile air conditioner - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for an automobile, and more particularly to an air conditioner for an automobile equipped with a means for detecting a failure of a cooling means or a heating means. BACKGROUND OF THE INVENTION For example, as disclosed in JP-A-56-82339,
In the conventional air conditioner, disconnection, short circuit of various sensors,
Although there is a detection display for failure such as motor lock,
Currently, there is no indication of failure detection for heating and cooling functions. [Object of the Invention] The present invention has been made in view of the above, and an object thereof is to detect a failure of a cooling means or a heating means, and at the time of displaying the failure detection, the heating means or the cooling means itself has a cause or other causes. An object of the present invention is to provide a method of diagnosing a failure in an air conditioner for a vehicle, which can inform whether there is any. SUMMARY OF THE INVENTION The present invention provides a cooler that cools air passing through an air conditioning duct, a heater that heats this cooled air, and a ratio that guides the cooled air to the heater and its bypass passage. Temperature control door to determine, temperature control door sensor to detect the opening of the temperature control door, vehicle temperature sensor to detect the vehicle compartment temperature, cooled air temperature sensor to detect the air temperature immediately after passing through the cooler, An air conditioner for an automobile equipped with an air conditioning control means for controlling the temperature control door according to a difference between a vehicle compartment temperature and a target set temperature, and for controlling operation of the cooler so that the cooled air temperature reaches a target value. In the apparatus, a temperature sensor failure diagnosing means for performing a failure diagnosis of these temperature sensors by comparing output values of the vehicle compartment temperature sensor and the cooled air temperature sensor with a determination value for diagnosis, and the temperature control door sensor. Temperature control door failure diagnosis means for performing a failure diagnosis of the temperature control door by determining whether the difference between the detected value of the temperature and the door target voltage value becomes a predetermined value or less within a predetermined time, and the vehicle compartment temperature and the target setting. The system includes a cooler / heater failure diagnosing means for making a failure diagnosis of the cooler and the heater by judging whether or not the difference from the temperature becomes a predetermined value or less within a predetermined time. As means, after the failure diagnosis of the vehicle interior temperature sensor, the cooled air temperature sensor and the temperature control door is performed, the failure diagnosis of the cooler and the heater is performed, and when the various failures are diagnosed. The feature is that it is displayed through a display. With such a configuration, not only the failure of the temperature sensors and the temperature control door is detected by the above-described series of various failure diagnoses, but also the failure of the cooler and heating means, which are the center of the air conditioner, is detected. . In particular, according to the present invention, in a series of air conditioning control routines, a temperature control door failure diagnosis including a cooled air temperature sensor and a vehicle interior temperature sensor failure diagnosis is performed before the failure diagnosis of the cooler and the heater. As a result, the following actions are performed with respect to the result display of the failure diagnosis of the cooler and the heater (display when a failure is detected). That is, the failure diagnosis of the cooler and the heater is performed at two points: (a) the difference between the vehicle interior temperature and the target set temperature, and (b) whether or not the difference falls below a predetermined value within a predetermined time. ,
(A) and (b) do not have normal values when the passenger compartment temperature sensor, the cooled air temperature sensor, and the temperature control door fail, so even if the cooler or heater does not fail, failure diagnosis is possible. Make a wrong decision when performing. However, as in the present invention, if the failure diagnosis is performed in advance before the failure diagnosis, whether the failure indication of the cooler and the heater is due to its own failure or another cause (vehicle interior temperature sensor, The occupant can be notified by distinguishing whether it is due to a cooling air temperature sensor or temperature control door failure. Embodiments of the Invention The present invention will be described in detail below with reference to the embodiments shown in FIGS. 1 to 5 and FIGS. 7 to 9 and FIGS. 6 and 10. FIG. 1 is an overall configuration diagram showing an embodiment of an automobile air conditioner of the present invention. The air conditioner for a vehicle according to this embodiment electrically inhales air from inside and outside the vehicle compartment, heats or cools it, and blows it out as air-conditioning air into the vehicle compartment. From the control unit 2 for controlling, the operation unit 3 for inputting start / stop of this device and the desired set temperature to the control unit 2, and the sensors for inputting the vehicle compartment temperature signal and the device state signal of the heat exchange unit 1 to the control unit 2. Configured. The heat exchange unit 1 has an outside air suction port 101 for sucking air from the outside of the vehicle compartment into the heat exchange section unit case 100, and a suction port door 111 for controlling opening / closing of the inside air suction port 102 for sucking air in the vehicle compartment, The suction door 111 includes a two-stage action negative pressure actuator 112 and a return spring 11.
It is controlled to 3 positions by 3. That is, each negative pressure working chamber of the negative pressure actuator 112 is connected to a negative pressure source such as a negative pressure pump via the electromagnetic valves 114 and 115, and the suction door 111 is energized by both the electromagnetic valves 114 and 115. If not, the inside air inlet 102 is closed by the force of the return spring 113 to bring the outside air into the state, and when both solenoid valves 114 and 115 are energized, the negative pressure actuator 112 is supplied to both negative pressure operating chambers. The outside air suction port 101 is closed by the generated negative pressure, and the inside air is sucked.
Further, when the solenoid valve 114 is energized and the solenoid valve 115 is not energized, negative pressure acts only on one negative pressure working chamber of the negative pressure actuator 112, so that the intake door 111 is stopped at the intermediate position in the above state. Then, both the outside air suction port 101 and the inside air suction port 102 are opened, and the inside and outside air is sucked. In addition, the heat exchange unit case 100 has a suction port 10
A blower 121 that draws in air from 1, 102 and sends it to a heat exchange unit described later is provided. The air volume of the blower 121 is controlled by controlling the applied voltage supplied to the motor 123 by the driver 122 controlled by the control unit 2. An evaporator 1 is provided downstream of the blower 121.
31 is provided, and this evaporator 131 constitutes a compression refrigeration cycle with a compressor 132, a condenser (not shown) expansion valve 133, etc., and serves as a cooler for the air passing therethrough. The compressor 132 is driven by an automobile engine via an electromagnetic clutch 132a, and its driving / non-driving is controlled by a control signal from the control unit 2 to excite / de-energize the electromagnetic clutch 132a by a compressor relay 132b. Is done by doing. A heater core 14 serving as a heater is provided downstream of the evaporator 131.
1 is provided, and the engine core water (warm water) of the automobile is circulated in the heater core 141.
Heat the air passing through 1. And the heater core 14
A temperature control door 142 is provided for controlling the heating amount by increasing or decreasing the amount of air passing through 1. The temperature control door 142 is rotated by a negative pressure actuator 145 connected to a negative pressure source via electromagnetic valves 143, 144 and a return spring 146. When the solenoid valves 143 and 144 are not energized, the negative pressure operating chamber of the negative pressure actuator 145 is electrically connected to the atmosphere via the solenoid valves 143 and 144.
The negative pressure does not act, and the temperature control door 142 rotates in the direction in which θ shown in FIG. 1 decreases due to the action of the return spring 146. In other words, the amount of air passing through the heater core 141 is increased. When the solenoid valve 143 is energized and the solenoid valve 144 is not energized, the negative pressure working chamber of the negative pressure actuator 141 is conducted to the negative pressure source via the solenoid valves 144 and 143, and negative pressure acts. As a result,
The temperature control door 142 rotates in the direction in which θ increases against the return spring 146. That is, the heater core 1
It rotates in a direction to reduce the amount of air passing through 41. Potentiometer 14 that operates in conjunction with the temperature control door 142
7 inputs a position signal corresponding to the position of the temperature control door 142 to the control unit 2 in the form of the voltage V _T (V _T increases as θ increases), and the control unit 2 performs specific processing. As will be described later, when the difference ΔV _T between the target position and the detected position is larger than a predetermined value, it is determined that the temperature control door 142 is out of order. Although the details will be described later, the temperature control door 142 is feedback-controlled in the above-described configuration, and the amount of air passing through the heater core 141 is from zero (θ increases) to 100% (θ of the blower air amount A sent by the blower 121). Is controlled to zero). In addition, the air that does not pass through the heater core 141 is
Through the bypass 103 provided in parallel with the heated air that has passed through the heater core 141, and is mixed into the heated air and blown into the vehicle interior. The air that has passed through the evaporator 131 and the heater core 141 or the bypass 103 is supplied to the upper air outlet 10 into the vehicle interior.
4, the air is blown into the vehicle interior from the lower air outlet 105 or the differential air outlet 106 to the windshield. A mode door 151 is provided to switch the air outlet to the passenger compartment, and the mode door 151 is controlled to the three positions by the two-stage action negative pressure actuator 152, like the intake door 111. The two negative pressure operating chambers of the negative pressure actuator 152 are connected to negative pressure sources via solenoid valves 153 and 154, respectively. When both solenoid valves 153 and 154 are not energized, a return spring 155 is used. The upper outlet 104 is closed and the air is blown out from the lower outlet 105. When both solenoid valves 153 and 154 are energized,
A negative pressure source is connected to both negative pressure operating chambers of the negative pressure actuator 152, the mode door 151 closes the lower outlet 105, and air is blown from the upper outlet 104. When the solenoid valve 153 is energized and the solenoid valve 154 is not energized, only one of the negative pressure working chambers of the negative pressure actuator 152 is connected to the negative pressure source, so that the mode door 151 is in the intermediate position of the above state, that is, Both the upper outlet 104 and the lower outlet 105 are opened, and the air is blown out from both outlets 104 and 105, which is a so-called bi-level state. The differential outlet 106 is opened and closed by a differential door 156 (normally, a small amount of blown air is present even when the differential door 156 is closed). The differential door 156 is
It is driven by a negative pressure actuator 158 connected to a negative pressure source via a solenoid valve 157 and a return spring 159. When the solenoid valve 157 is energized, negative pressure acts on the negative pressure actuator 158, the differential door 156 opens against the return spring 159, and when the solenoid valve 157 is not energized, the differential door 156 is closed by the action of the return spring 159. To be Immediately downstream of the evaporator 131, the air temperature immediately after passing through the evaporator 131, i.e., the cooling air temperature sensor 160 consisting of such as a thermistor for detecting the cooled air temperature T _C
Is provided and the cooled air temperature T _C is input to the control unit 2 in the form of the voltage V _C. Also, is attached is cabin temperature sensor 170 in a proper position of the passenger compartment, is input to the control unit 2 of the vehicle compartment temperature T _R in the form of a voltage V _R. By the way, the temperature sensor signals V _C and V having the characteristics shown in FIG.
_R , that is, 4.5 to 0.5 V, that is, -17 to 8
0 ° C. is converted into a digital value by the A / D conversion circuit 21 shown in FIG. However, in the case of failure detection of the temperature sensors 160 and 170, a voltage corresponding to 80 ° C. necessary for failure detection can be input for the low voltage side due to a short circuit or the like, but -17 ° C. for the high voltage side due to disconnection or the like. Since the voltage corresponding to is not sufficient, the voltage corresponding to −50 ° C. (4.9
5V) to compare the temperature sensor signals,
As shown in FIG. 5, the comparison circuit 24 is provided to detect the failure of the temperature sensors 160 and 170. The control unit 2 includes an A / D converter 21 for converting an analog signal from the sensors such as the temperature sensors 160 and 170 and the operation unit 3 into a digital signal, a comparison circuit 24 for detecting a sensor failure, and an A / D converter 21. And an interface circuit 2 for controlling each device of the heat exchanging unit 1 in accordance with an output signal of the microcomputer 22 and the microcomputer 22 which performs arithmetic processing using a digital signal from the operation unit 3.
3 and 3. In addition, the microcomputer 2
The reference numeral 2 indicates the vehicle compartment temperature detected by the temperature sensor 170 and the operating section 3 in addition to the failure diagnosis means for the temperature sensors 160 and 170 and the failure diagnosis means for the temperature control door 142 described later. It is determined whether or not the difference from the set target set temperature is less than or equal to a predetermined value.
Refrigeration cycle (cooler) such as heater core 141
It has a failure detection counter function (failure diagnosis means) for diagnosing that the (heater) has a failure. FIG. 2 is a functional block diagram of the microcomputer 22. The interface circuit 23 includes electromagnetic valves 114, 115, 143, 144, 153, 154, 15 of the heat exchange section 1.
7, transistors 231 to 238 as switch elements for controlling the compressor relay 132b, motor 123
And a D / A converter 239 that supplies an analog voltage to a driver 122 that supplies electric power. The operation unit 3 includes an air conditioner switch (not shown) for starting and stopping the apparatus, a temperature setter 31 for setting a desired temperature in the vehicle interior, a dehumidifying switch 32 for manually dehumidifying the vehicle interior, and a diff outlet 106. It is composed of a differential switch 33 for blowing air to the windshield, a failure display lamp 34, and the like. And the temperature setter 31
The desired temperature of the passenger compartment (target set temperature T _S ) set by is input to the control unit 2 as the voltage V _S , and the operation signals V _DEH and V _{DEF of the} dehumidifying switch 32 and the differential switch 33 are input.
Are input to the control unit 2 in the form of high and low voltages. Next, the operation of the automobile air conditioner configured as described above will be described. 3 and 4 are operation flowcharts of the control unit 2. The numbers in parentheses in FIGS. 3 and 4 are step numbers indicating the flow order. As shown in the figure, the operation of the present apparatus is the initialization of steps (201) to (203) of FIG. 3, the main routine of repeating steps (204) to (218) infinitely, and the processing of this main routine of FIG. One cycle of the main routine (about 1 in the embodiment)
Second), and an interrupt routine of steps (220) to (228) for processing at a cycle of several hundredths of a second (1/100 second in the embodiment). First, when this device is activated by the air conditioner switch,
The I / O data of the microcomputer 22 of the control unit 2 is set to the initial value determined in step (201), and the RAM of the microcomputer 22 is set in step (202).
Is cleared. Next, the position of the temperature control door 142 (θ = 0)
The voltage V _{T of the} potentiometer 147 corresponding to
It is converted into a digital value [V _T ] by the converter 21 and read as an initial value of the door reference position (203). This door reference position signal is an interrupt routine (22
4) Monitoring and updating (temperature control door reference position setting,
Details of the renewal are described in JP-A-57-84216). Next, the main routine is performed. The voltage V _S and the vehicle compartment temperature T _R corresponding to the target set temperature T _S set by the operation unit 3
Corresponding to the voltage V _R and the voltage _C corresponding to the temperature T _C of the air to be cooled are respectively subjected to digital values [V _S ] [V _R ] [through the conversion circuit shown in FIG. 5 and the process shown in FIG. V
_C ] is input to the microcomputer 22 (204). FIG. 7 is a detailed flowchart of the step (204) in FIG. Input the voltage V _S corresponding to T _S (240
0), the cooled air temperature sensor 160 and the passenger compartment temperature sensor 170 are selected (204-2), and the output voltage is A-
The digital amount is converted by the D converter 21 and input to the microcomputer 22 (204-3). The microcomputer 22 determines whether or not the signal voltage is low due to a circuit short circuit of the temperature sensors 160 and 170 (204-4), and if the signal voltage is low, it is considered to be a short circuit and the corresponding failure flag is determined. The microcomputer 2
It is set in the memory No. 2 (204-5). Furthermore, (204-6) when the object is inside air temperature _{T R,} the set temperature T _S to replace the voltage corresponding to the ambient temperature as manual air conditioning to use by raising and lowering (204-7), the evaporator 131 immediately after When the temperature of the cooled air is T _C , the evaporator 1
In order to prevent freezing of 31, the voltage is replaced with a voltage corresponding to a low temperature (204-8). When the signal voltage exceeds the upper limit value that can be converted into a digital value (204-9), it exceeds the reference voltage of 4.95 V for detecting the failure created by the resistors 242 and 243 (see FIG. 5). It is judged whether or not (204-10), and when it exceeds, it is regarded as a failure such as circuit disconnection of the temperature sensors 160 and 170, and the corresponding failure flag is set to the microcomputer 22.
(204-11), and the process proceeds to step (204-6) (204-12). The voltage V _T corresponding to the position of the temperature control door 142 is read by a timer interrupt, which will be described later. Next, returning to FIG. 3, [V _R], [V _C] is the cabin temperature, the cooling air temperature corresponding digital values by the conversion map stored in the ROM of the microcomputer 22 [T _R], [ T _C ] (205). [V _S ] is converted into a digital value [T _S ] of the target set temperature T _S by a first-order conversion formula (206). Then, the deviation between the target setting temperature [T _S] and vehicle compartment temperature [T _R] [ΔT]
= _{[T S]} - Request _{[T R]} (207). Next, the deviation [ΔT] is used to detect a failure in the cooler and heater functions. When the heater function, the cooler function, and the temperature control door 142 are functioning normally, the failure detection counters provided in the memory of the microcomputer 22 which are counted by the time interrupt described later are set in the main routine. It is cleared in step (208) of the failure diagnosis processing. When the abnormal state continues and the counter is no longer cleared, when the counter reaches a predetermined value, it is considered that the corresponding function has failed, and the failure flag corresponding to the memory in the microcomputer 22 is set. FIG. 8 is a detailed flowchart of step (208) in FIG. First, it is determined whether or not the absolute value of the difference between the temperature control door target voltage and the actually detected voltage is equal to or less than a predetermined value ΔQ _T (208-1). Clear the detection counter (20
8-2). Further, it is determined whether the difference between the target set temperature and the inside air temperature is less than or equal to a predetermined value ΔT (208-
3) When the value is not more than the predetermined value, the heater failure detection counter is cleared (208-4). Also, it is determined whether the control signal is in the cooler region (X <0) (208-
5) In the heater area (X> 0), the counter for detecting the cooler failure is cleared (208-8), while in the cooler area (X <0), the target set temperature and the inside air temperature are further It is judged whether or not the difference between
8-6), the counter for detecting the cooler failure is cleared when ΔT 'or less is normal (208-7). In the failure display processing step (208-9), if any of the failure detection flags is set in the memory of the microcomputer 22, the failure display lamp 34 of the operation unit 3 is turned on to notify the driver. . The above-mentioned failure detection counter counts the failure detection counter processing (227) shown in FIG.
Done in. The temperature control door failure detection counter is incremented (227-1), and when the temperature control door failure detection counter reaches a number corresponding to a predetermined time (for example, 10 seconds) (227-2), the temperature door failure is detected. The detection flag is set in the memory of the microcomputer 22 (227-3).
Further, the heater failure detection counter is counted up (227-4), and when the heater failure detection counter reaches a number corresponding to a predetermined time (for example, 20 minutes), (2
27-5), and sets the heater failure detection flag in the memory of the microcomputer 22 (227-6). Also,
The cooler failure detection counter is incremented (227
-7), when the cooler failure detection counter reaches a number corresponding to the lapse of a predetermined time (for example, 20 minutes) (227-
8) Set the cooler failure detection flag to the microcomputer 2
It is set in the memory No. 2 (227-9). Further, returning to FIG. 3, next, [X] = k [ΔT] +1
A PI calculation of / τ∫ [ΔT] dt is performed. First, the integral term of the above equation is calculated by the timer processing (22
It is determined by adding the temperature deviation [ΔT] every predetermined time designated by 6) (209). Further, the control signal [X] is obtained by adding k (ΔT) to this integral term (210). The above k and τ are constants determined by the control system (the details of the above PI calculation processing are shown in Japanese Patent Application No. 55-57836). When a dehumidifying operation is performed by the dehumidifying switch 32, the temporary correction value [ΔX] is added as the final processing in step (210) to obtain the corrected value. This dehumidifying operation will be described later. In this way, the control signal obtained [X] is the passenger compartment temperature T _R
Is an amount commensurate with the amount of heat required as a vehicle compartment heat load in the process of controlling the temperature to a target set temperature T _S , and in this embodiment, k>
Since 0, τ> 0 is selected, the heating power is large when [X]> 0, and the heating power is large as the [X] value is large, and the cooling power is large when [X] <0. A larger −X] value means that a larger cooling force is required as a vehicle compartment heat load. The operation of the air conditioner based on the value of the control signal [X] will be described with reference to FIG. FIG. 10 is an operation explanatory diagram of the heat exchange section 1 of FIG. 1, and the horizontal axis represents the control signal [X].
Are shown. First, the temperature door target voltage [V _T0 ] for the control signal [X] is calculated (211). This target voltage [V _T0 ] is a linear expression relating to [X], and [X] is

At [0], [V _T0 ] = [V _T1 ], and a predetermined positive value [X ₃ ] of [X] satisfies [V _T0 ] = [V _T2 ]. Here, in [ _VT1 ], the temperature control door 142 has the heater core 1
This corresponds to the voltage by the potentiometer 147 in the state where the passage to 41 is closed (θ is maximum), [V _T2 ].
Is in a state where the passage to the heater core 141 is completely opened (θ =
0) corresponds to the voltage by the potentiometer 147. Next, converts the voltage V _T by the potentiometer 147 in the interrupt processing routine as the position signal of the temperature control door 142 reads the digital value by the A-D converter 21 into [V _T] (222). Next, the position control of the temperature control door 142 is performed by comparing the target voltage [V _T0 ] and [V _T ] (223). That is, first, [ΔV _T ] = [V _T0 ] − [V _T ] is calculated, and [ΔV _T ] is set for [ΔV _TP ]> 0
When V _T ] ≧ [ΔV _TP ], “1”, [ΔV _T ] <[ΔV _TP ]
Control signal [T ₁ ] which becomes “0” at [−ΔV _TP ] ≦
A control signal [T ₂ ] that produces “1” when [ΔV _T ] ≦ [ΔV _TP ] and “0” in a range other than the above is created. When the control signals [T ₁ ] and [T ₂ ] are "1", the switch elements 233 and 234 are turned on, the solenoid valves 143 and 144 are energized, and when they are "0", they are not energized. By the above operation, as described above, the temperature control door 142 is rotated in the direction of increasing θ by [ΔV _T ]> [ΔV _TP ] and [ΔV _T ] <
At [-ΔV _TP ], the temperature control door 142 is rotated in the direction in which θ decreases. In addition, [-ΔV _TP ] ≦ [ΔV _T ] ≦ [ΔV
_In the range of _TP ], the temperature control door 142 is in a stationary state, and the position θ of the temperature control door 142 at this time is a position corresponding to the target voltage [V _T0 ] corresponding to the control signal [X]. Next, returning to step (215) of the main routine,
The target temperature [T _C0 ] of the cooled air temperature T _C is obtained by the following. When [X] ≦ [X ₂ ] with respect to a predetermined negative value [X ₂ ] of [X], [T _C0 ] is the lowest possible value [T _C1 ] immediately before freezing of the evaporator surface (this embodiment In the range of [X] ≧ [X ₂ ], [X] ≦ [X ₂ ]
And [T _C1 ], [X] =

[0] is a predetermined value [T _C2 ] (in the present embodiment, a value obtained by a linear expression connecting two points at 25 ° C., where [X] =

The vicinity of [0] is a region where the vehicle interior heat load does not require heating power or cooling power, and the outside air temperature T ₀ is close to the target set temperature T _S. In this region, since it is almost unnecessary to operate the cooling means, [T _C2 ]
≈ [T _S ] is set. The next step (216), the target temperature of the cooling air temperature [T _C0] is compared with the cooling air temperature [T _C], the temperature difference [[Delta] T _C] = [T _C0] - [T _C] Is calculated, and the compressor control signal [C] is generated by the value of this [ΔT _C ]. That is, [ΔT _C ] ≧

In [0], [C] is “0”,
[ΔT _C ] <

At [0], [C] becomes "1". When the compressor control signal [C] is "1", the switch element 235 is turned on at the time of step (218) to energize the compressor relay 132b. Then, when the compressor relay 132b is turned on, the magnet clutch 132a is excited and the compressor 132 is operated,
The air passing through the evaporator 131 is cooled and the cooled air temperature T _C is lowered. If the cooled air temperature T _C decreases, [ΔT _C ] ≧

[0] and [C] =

It becomes [0]. Therefore, at the time of the final step (218) of the main routine, the compressor 132 becomes inoperative. Thus, the compressor 132 is operated by repeating the non-operation, the cooling air temperature T _C is maintained at the target temperature [T _C0] closer determined by the control signal (X).
However, as described above, in the range of [X] ≧ 0, the vehicle interior heat load requires heating power, and the target set temperature T _S >
At the vehicle outside air temperature T ₀ , on the other hand, T _C0 > T _C2 ≈T _S ,
And since the blow-in door 111 sucks in the air outside the passenger compartment,
The temperature of the air sent to the evaporator 131 is the outside air temperature T _{0 of the} passenger compartment.
Close to. Therefore, even if the cooling means does not operate [ΔT
_C ]> 0, and the compressor 132 never operates. Then, [T _C ] ≈ [T ₀ ]. The blower air volume A is approximately proportional to the voltage V _F supplied to the motor 123. The voltage V _F supplied to this motor 123
Is controlled as follows. First, the target voltage [V _F] corresponding to the control signal (X). Further, with respect to a predetermined negative value [X ₁ ] and positive value [X ₄ ] of [X], [X] ≦ [X ₁ ] and [X] ≧ [X ₄ ] respectively, the maximum value [V _F1 ] (12V in this embodiment), the negative value [X ₂ ] and the positive value [X ₃ ] are set to the maximum value [VF ₂ ] (4V in this embodiment). Then, [X ₁ ] ≦ [X] ≦
In the range of [X _2], defines the [X _1] in [V _F1], [X _2] In the linear equation connecting two points as the [V _F2] [V _F], [X _3] ≦ [ In the range of X] ≦ [X ₄ ], [X ₃ ]
In [V _F2], define the [V _F] by linear equation connecting two points as the [V _F1] in _{[X 4]} (217). The target value [V _F ] obtained as described above is calculated in step (21
8), the DA converter 239 of the interface circuit 23
Is converted into an analog voltage V _FS , and the voltage V _F applied to the motor 123 is controlled by the driver 122 controlled by this voltage V _FS , and the motor 123 is driven. According to the value of the control signal [X], when [X ₁ ] or less, V _F is the maximum, that is, the blower air volume A is the maximum A _MAX ,
Between [X ₁ ] and [X ₂ ], the blower air volume A is maximum A
It decreases almost linearly from _MAX to the minimum A _{MIN, and keeps the} minimum A _MIN between [X ₂ ] and [X ₃ ] and _keeps [X ₃ ] and [X ₃
Between _4] increases linearly from the minimum A _MIN to the maximum A _MAX, the [X _4] above, is continuously controlled so as to maximize A _MAX. In addition to the above operation, the suction door 111 and the mode door 151 are controlled by the value of the control signal [X] during the operation. That is, [X] ≦

[1] for [0], [X] ≧

Control signal [I ₁ ] that becomes “0” when [0], “1” when [X] ≦ [X ₅ ] and control signal [I that becomes “0” when [X] ≧ [X ₅ ]
₂ ] is made (212). Note that [X ₅ ] is a negative value,
It is a value of [X ₁ ] <[X ₅ ] <[X ₂ ]. When the control signals [I ₁ ] and [I ₂ ] are "1", the switch elements 231 and 232 are turned on in step (218) to energize the solenoid valves 114 and 115, and when the control signals are "0", the solenoid valves No electricity is supplied to 114 and 115. When the control signal [X] is [X] ≦ _{[X 5],} as described in _{[I 1],} is energized _{[I 2]} are both "1", the solenoid valve 114 and 115, inlet doors 111 Is brought into a state of sucking the inside air by the actuator 112. [X] ≧

At the time of [0], [I ₁ ] and [I ₂ ] are both “0”, and the suction port door 111 is pulled by the return spring 113 to be in the state of sucking the outside air. [X ₅ ] ≦ [X] ≦

In [0], [I ₁ ] is “1”,
Since [I ₂ ] is “0”, the suction port door 111 is at the intermediate position, and the inside air is sucked. Similarly, the mode door 151 is also controlled by the value of the control signal [X]. However,

[0] <[X ₆ ] <[X ₇ ] <
[X ₆ ], [X ₇ ] which are [X ₃ ] are predetermined. [X] <in _{[X 7]} "1", [X] ≧ _{[X 7]} in the "0"
Of the control signal [0 ₁ ] and [ ₁ ] when [X] <[X ₆ ] and [0] when [X] ≧ [X ₆ ]
₂ ] is made (213). Then, the mode door 151 is driven as follows in step (218) according to the values of the control signals [0 ₁ ] and [0 ₂ ]. When [X] <[X ₆ ], the control signals [0 ₁ ] and [0 ₂ ] are both “1”, the switch elements 236 and 237 are both turned on, the solenoid valves 153 and 154 are energized, and the mode door is turned on. The actuator 152 is in a state of being blown upward by the actuator 152. When [X]> [X ₇ ], both [0 ₁ ] and [0 ₂ ] are “0”, the solenoid valves 153 and 154 are not energized, and the mode door 151 is blown downward by the return spring 155. To be in a state. In [X ₆ ] ≦ [X] ≦ [X ₇ ], [0 ₁ ] is “1”,
Since [0 ₂ ] becomes “0”, the solenoid valve 153 is energized, and the solenoid valve 154 is not energized.
1 is an intermediate position, which is a state of vertical blowing. According to the present embodiment, in the processing step of the main routine of the air conditioning control, in addition to the failure diagnosis of the cooled air temperature sensor 160 and the passenger compartment temperature sensor 170 such as a short circuit or disconnection, or the temperature control door 142, Since the failure diagnosis of the refrigeration cycle and the heater core is carried out on the premise of these failure diagnosis, the failure can be accurately detected. That is, the failure diagnosis of the refrigeration cycle and heater core is
(A) The difference between the passenger compartment temperature and the target set temperature, and (b) the difference is less than or equal to a predetermined value within a predetermined time. The two points are (a) and (b): If the temperature sensor 170, the cooled air temperature sensor 160, and the temperature control door 142 are out of order, the values will not be normal values. Therefore, even if there is no failure in the refrigeration cycle or the heater core, an erroneous determination is made when performing failure diagnosis. However, if the failure diagnosis is performed in advance before the failure diagnosis as in the present embodiment, whether the failure indication of the cooling means and the heating means is due to its own failure, or another cause (vehicle interior temperature sensor, The occupant can be notified by distinguishing whether it is due to the cooled air temperature sensor or the temperature control door failure. As a result, information about the failure detection of the central equipment such as the refrigeration cycle and the heater core can be notified early and with high reliability, and the occurrence of the secondary failure can be prevented. [Effects of the Invention] As described above, according to the present invention, it is possible to detect a failure of the cooling means and the heating means that are the center of the air conditioner, and whether the failure detection display is due to its own failure or another cause. Since it is possible to tell the occupant whether it is a thing,
This makes it possible to take prompt and appropriate measures for repairs and prevent secondary failures from occurring.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an automobile air conditioner of the present invention, FIG. 2 is a functional block diagram showing an embodiment of the microcomputer shown in FIG. 1, and FIGS. An operation flowchart showing an embodiment of the operation of the control unit of FIG.
FIG. 5 is a circuit diagram showing an embodiment of the temperature sensor voltage detector of FIG. 1, FIG. 6 is a characteristic diagram of the temperature sensor, and FIG.
A flow chart detailing step (204) of the figure,
FIG. 8 is a flow chart showing the details of step (208) in FIG. 3, FIG. 9 is a flow chart showing the details of step (227) in FIG. 4, and FIG. 10 is an explanation of the operation of the heat exchange section in FIG. It is a diagram. DESCRIPTION OF SYMBOLS 1 ... Heat exchange part, 2 ... Control part, 3 ... Operation part, 21 ... AD
Exchanger, 22 ... Microcomputer, 23 ... Interface circuit, 24 ... Comparison circuit, 31 ... Temperature setting device, 3
4 ... Failure display lamp, 100 ... Heat exchange unit unit case, 103 ... Bypass, 111 ... Suction port door, 121 ...
Blower, 131 ... Evaporator, 141 ... Heater core, 14
2 ... Temperature control door, 147 ... Potentiometer, 151 ... Mode door, 160 ... Cooled air temperature sensor, 170 ...
Cabin temperature sensor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tsuguhiro Okada 2520 Takaba, Takata, Ibaraki Pref., Sawa Plant, Hitachi, Ltd. (72) Eiichi Otsu 2520 Takata, Katsuta, Ibaraki, Ltd. Hitachi, Ltd. Sawa Plant (72) Inventor Masanori Kubota 3085, Higashiishikawa Nishikouchi, Katsuta City, Ibaraki Prefecture 5 days Automobile Engineering Co., Ltd. (56) Reference JP 54-42584 (JP, A)

Claims (1)

[Claims] 1. A cooler for cooling air passing through an air-conditioning duct, a heater for heating the cooled air, and a temperature control for determining a ratio of guiding the cooled air to the heater and its bypass passage. A door, a temperature control door sensor that detects the opening of the temperature control door, a vehicle compartment temperature sensor that detects a vehicle compartment temperature, a cooled air temperature sensor that detects an air temperature immediately after passing through the cooler, a vehicle compartment temperature and In an automobile air conditioner including an air-conditioning control unit that controls the temperature control door according to a difference from a target set temperature, and that controls the operation of the cooler so that the cooled air temperature becomes a target value, Temperature sensor failure diagnosis means for performing failure diagnosis of these temperature sensors by comparing the output values of the passenger compartment temperature sensor and the cooled air temperature sensor with the judgment values for diagnosis, and the detected value of the temperature control door sensor A temperature control door failure diagnosis means for diagnosing temperature control door failure by determining whether or not the difference from the target voltage value falls below a predetermined value within a predetermined time, and the difference between the passenger compartment temperature and the target set temperature Is provided with a cooler / heater failure diagnosis means for performing a failure diagnosis of the cooler and the heater by determining whether or not the value becomes a predetermined value or less within a predetermined time. After performing a failure diagnosis of the vehicle interior temperature sensor, the cooled air temperature sensor and the temperature control door, a failure diagnosis of the cooler and the heater is performed, and when the various failures are diagnosed, an indicator is displayed. A failure diagnosis method for an air conditioner for a vehicle, which is characterized by performing a display to that effect.