JPS6099709A - Car air-conditioner - Google Patents

Abstract

PURPOSE:To detect fault of temperature regulating door easily, by displaying fault of door if the absolute value of the difference between the target voltage indicating the target position of said door and the output voltage of potentiometer indicating the position of door after control will exceed over predetermined level. CONSTITUTION:Upon starting of switch by means of an air-conditioning switch, the voltage VT of potentiometer 147 corresponding with the position of temperature regulating door 142 is converted into digital level and read in as the initial referential position of door. When abnormal condition of said door 142 continues to disable clearing of counter, it is considered to be fault of such function as corresponding to arrival of counter to predetermined count thus to set a corresponding fault flag in a memory of microcomputer 22. In other word, if the absolute value of the difference between the target voltage of temperature regulating door and actually detected voltage has exceeded over predetermined level DELTAQ, any one fault detection flag is set in memory of computer 22 to light a fault indication lamp 34 in the operating section 3 to alarm fault to the operator.

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to an air conditioner for an automobile, and particularly relates to an air conditioner for an automobile equipped with a failure detection means suitable for detecting a failure of a temperature control door. [Background of the Invention] Conventional air conditioners for automobiles have problems such as disconnection of various sensors,
Detects faults such as short circuits and motor locks. Although there are examples of display, failure detection of temperature control door 1
I can't find any examples of this being displayed. [Object of the Invention] The present invention has been made in view of the above, and an object of the present invention is to provide an air conditioner for an automobile that can easily detect a failure of a temperature control door. [Summary of the Invention] A feature of the present invention is that a target voltage indicating the target position of the temperature control door and a target voltage for indicating the target position of the temperature control door to a microcomputer that controls the temperature control door according to the difference between the vehicle interior temperature and the target set temperature. When the absolute value of the difference between the voltage given from the potentiometer linked to the temperature control door indicating the position after control is larger than a predetermined value, it is determined that the temperature control door is malfunctioning, and the malfunction is displayed on the malfunction display means. The point is that it is equipped with a detection means. [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 7 to 9, as well as FIGS. 6 and 10. FIG. 1 is an overall configuration diagram showing an embodiment of an air conditioner for an automobile according to the present invention. The automotive air conditioner of this embodiment includes a heat exchange section 1 that sucks air from outside and outside the vehicle interior, heats or cools it, and blows it out into the vehicle interior to be air-conditioned. A control unit 2 that controls the device, and an operation unit 3 that inputs the start/stop of this device and the desired set temperature to the control unit 2.
and sensors for inputting a vehicle interior temperature signal and a heat exchanger 10 equipment status signal to the controller 2. The heat exchanger 1 includes an inlet door 111 that controls the opening and closing of an outside air inlet 101 that sucks air from outside the vehicle into the heat exchanger unit case 100 and an inside air inlet 102 that sucks air inside the vehicle. The suction door 111 is controlled to the third position by a two-stage action negative pressure actuator 112 and a return spring 113. That is, each negative pressure working chamber of the negative pressure actuator 112 is connected to the solenoid valve 114, 1
15 to a negative pressure source such as a negative pressure pump,
When both the solenoid valves 114 and 115 are not energized, the suction port door 111 closes the inside air suction port 102 by the force of the return spring 113 to take in outside air, and when both the solenoid valves 114 and 115 are energized, , the outside air suction port 101 is closed by the negative pressure supplied to both negative pressure working chambers of the negative pressure actuator 112, and the inside air suction state is established. Further, when the solenoid valve 114 is energized and the solenoid valve 115 is not energized, negative pressure acts only on one negative pressure operating chamber of the negative pressure actuator 112, so that the suction door 11
1 stops at an intermediate position in the above state, and both the outside air suction port 101 and the inside air suction port 102 are opened, and the inside and outside air is sucked. The heat exchanger unit case 100 also includes a suction port 10.
A blower 121 is provided which sucks air from air pumps 1 and 102 and sends it to a heat exchange section to be described later. The air volume by the blower 121 is controlled by controlling the applied voltage supplied to the shimo motor 123 by the driver 122 which is controlled by the control unit 2 . Evaporator 1 is downstream of the blower 121.
The evaporator 131 constitutes a compression refrigeration cycle with a compressor 132, a condenser (not shown), an expansion valve 133, etc., and serves as a cooling means for the air passing through it. The compressor 132 is driven by the engine of the automobile via a magnetic latch 132a, and its driving and non-driving are controlled by a control signal from the control unit 2. The compressor relay 132b excites the magnetic latch 132a. , by de-energizing. A heater core 1 serving as a heating means is downstream of the evaporator 131.
41 is provided, and automobile engine cooling water (warm water) is circulated through this heater core 141 to heat the air passing through the heater core 141. A temperature control door 142 is provided for controlling the amount of heating by increasing or decreasing the amount of air passing through the heater core 141. The temperature control door 142 is rotated by a negative pressure actuator 145 connected to a negative pressure source via electromagnetic valves 143 and 144 and a return spring 146. When neither of the solenoid valves 143 and 144 are energized, the negative pressure operating chamber of the negative pressure actuator 145 is communicated with the atmosphere via the solenoid valves 143 and 144, so that no negative pressure acts on the temperature control door 142. 146 causes the shaft to rotate in the direction in which θ shown in FIG. 1 decreases. In other words, the heater core 14
This will increase the amount of air passing through 1. Solenoid valve 1
43 is energized and the solenoid valve 144 is not energized, the negative pressure actuating chamber of the negative pressure actuator 141 is connected to the solenoid valve 144.
, 143 to the negative pressure source, negative pressure! Force acts. As a result, the temperature control door 142 rotates in a direction in which θ increases against the return spring 146. That is, it rotates in a direction that reduces the amount of air passing through the heater core 141. A potentiometer 147 that operates in conjunction with the temperature control door 142 inputs a position signal corresponding to the position of the temperature control door 142 to the control unit 2 in the form of a voltage VT (VT increases as θ increases), the control unit 2 The specific process will be described later, but when the difference ΔVT between the target position and the detected position is larger than a predetermined value, it is determined that there is a failure. Although details will be described later, the temperature control door 142 is feedback-controlled with the above configuration, and the amount of air passing through the heater core 141 is increased from zero (θ increases) of the blower air amount A sent by the blower 121. It is controlled up to 100 inches (θ is zero). Further, the air that does not pass through the heater core 141 is energized through a bypass 103 provided in parallel to the heater core 141, and is mixed with the heated air that has passed through the heater core 141 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 blown into the vehicle interior through the upper outlet 1o4, the lower outlet 105, or the differential outlet 106 toward the windshield. A mode door 151 is provided to switch the air outlet into the vehicle interior.
Similarly to 1, it is controlled to the 3rd position by a two-stage action negative pressure actuator 152. The two negative pressure working chambers of the negative pressure actuator 152 are connected to a negative pressure source via solenoid valves 153 and 154, respectively, and when both of the solenoid valves 153 and 154 are not energized, the return spring 155
Otherwise, the upper outlet 104 is closed and the air is passed through the lower outlet 10.
It is blown out from 5. Furthermore, when both the solenoid valves 153 and 154 are energized, the negative pressure actuator 152
A negative pressure source is connected to both negative pressure working chambers of the mode door 151.
closes the lower outlet 105, and air is blown out from the upper outlet 104. When the solenoid valve 153 is energized and the solenoid valve 154 is not energized, only one negative pressure working chamber of the negative pressure actuator 152 is connected to the negative pressure source, so the mode door 151 is in the intermediate position of the above state, that is, Upper outlet 1
04, when both lower air outlets 105 are opened, air is blown out from both secondary outlets 104 and 105, resulting in a so-called pie level state. The differential air outlet 106 is opened and closed by a differential door 156 (usually configured so that a small amount of Suita air is present even when the differential door 156 is closed). The differential door 156 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, and the differential door 156 opens against the return spring 159. When the solenoid valve 157 is not energized, the differential door 156 is opened by the action of the return spring 1590. Closed. Immediately downstream of the evaporator 131, a discharge air temperature sensor 160 consisting of a thermistor or the like is provided to detect the temperature of the air immediately after passing through the evaporator 131, that is, the discharge air temperature Tc. It is input to the control unit 2 in the form of . In addition, a vehicle interior temperature sensor 170 is installed at an appropriate position in the vehicle interior.
The vehicle interior temperature TR is input to the control unit 2 in the form of a voltage VR. By the way, the temperature sensor signals VC, V with the characteristics shown in FIG.
R, i.e. 4.5~0.5■, Tsumashi, -17~8
01? is converted into a digital quantity by the A-D conversion circuit 21 shown in FIG. 5 and input to the microcomputer 22. However, in the case of failure detection, the voltage corresponding to 80C required for failure detection can be input for the low voltage side due to short circuits, etc., but for the high voltage side due to disconnections, etc.
Since the voltage corresponding to -17C is sufficient, -5
In order to compare the temperature sensor signals with reference to the voltage (4.95V) corresponding to 0C, a comparison circuit 24 is provided as shown in FIG. 4, and a failure of the temperature sensors 160, 170 is detected. . The control unit 2 includes sensors such as temperature sensors 160 and 170 and an A-D converter 21 that converts analog signals from the operation unit 3 into digital signals, a comparison circuit 24 for sensor failure detection, and an A-D converter 21. A microcomputer 22 performs arithmetic processing using digital signals from the operating section 3, and an interface circuit 23 controls each device in the heat exchange section 1 using output signals from the microcomputer 22. FIG. 2 is a functional block diagram of the microcomputer 22. The interface circuit 23 is
Solenoid valves 114, 115° 143, 144 of heat exchange section 1,
153, 154, 157, compressor relay 132b
Transistors 231 to 231 as switch elements that control
238, driver 122 supplying power to motor 123;
It also includes a DA converter 239 that supplies an analog voltage to the DA converter 239. The operation unit 3 includes an air conditioner switch (not shown) for starting and stopping this device, a temperature setting device 31 for setting a desired temperature in the vehicle interior, a dehumidification switch 32 for manually dehumidifying the interior of the vehicle, and a differential air outlet 106. It consists of a differential switch 33 that blows air out to the windshield, a malfunction indicator lamp 34, and the like. And the temperature setting device 31
Desired temperature of the passenger compartment (target set temperature Ts
) is input to the control unit 2 as the voltage Vs, and the operation signal Vazu+V o of the dehumidification switch 32 and the differential switch 33
1F is input to the control unit 2 in the form of a voltage level. Next, the operation of the automobile air conditioner configured as described above will be explained. 3 and 4 are operation flowcharts of the control section 2. FIG. The numbers in parentheses in FIGS. 3 and 4 are step numbers indicating the order of the flow. As shown, the operation of this device is as follows:
During the initialization of steps (201) to (203) in FIG. 3, the main routine that repeats an infinite cycle of steps (204) to (218), and the processing of this main routine in FIG. (about 1 second in the example)
The interrupt routine consists of steps (220) to (228) which are processed 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 I10 data of the control unit 20 microcomputer 22 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
) corresponding to the voltage V of the potentiometer 147? is A
-D converter 21 converts it into a digital quantity [VT] and reads it as the initial value of the door reference position (203). Note that this door reference position signal is used in the interrupt routine (22
4) Monitored and updated (temperature control door reference position setting,
Details regarding the update are described in Japanese Patent Application Laid-Open No. 57-84216). Next, move on to the main routine. A voltage Vg corresponding to the target temperature TII set by the operation unit 3. The voltage VR% corresponding to the vehicle interior temperature TB, the voltage Vc corresponding to the discharge air temperature Tc, is converted into a digital value (Va
) = (N'i:l, (Vc:l) is converted to and input to the microcomputer 22 (204). Fig. 7 is a detailed flowchart of step (204) in Fig. 2. Corresponding to Ts Please input the voltage Vg 240
-0), discharge air temperature sensor 160, cabin temperature sensor 1
70 (204-2), its output voltage is converted into a digital quantity by the A-D converter 21, and input to the microcomputer 22 (204-3). The microcomputer 22 determines whether the signal voltage has become low due to a short circuit, etc. 204-4), and if it is low, it is assumed that there is a short circuit, and a corresponding failure flag is set in the memory of the microcomputer 22. (204-5
). Furthermore, when the target is the internal air temperature TR (2046)
% By increasing and lowering the set temperature T8, it can be replaced with a voltage equivalent to room temperature so that it can be used as a manual king AC controller (204
-7), when the discharge air temperature immediately after the evaporator 131 is Tc, the voltage is replaced with a voltage corresponding to a low temperature in order to prevent the evaporator 131 from freezing (204-8). If the signal voltage exceeds the upper limit that can be converted into a digital quantity, (204-
9), determine whether the reference voltage of 4.95 V for fault detection produced by resistors 242 and 243 (see Figure 5) is exceeded (204-10), and if it is, the wire is disconnected. 204-11), and the process moves to step (204-6) (204-12). Note that reading of the voltage VT corresponding to the position of the temperature control door 142 is performed using a dyma interrupt, which will be described later. Next, returning to FIG. 3, (VR) and (Vc) are digital values [T
II], [Convert to Te3 (205). (Vs) is converted into a digital value (Ts) of the target set temperature T8 using a first-order conversion formula (206). Then, calculate the deviation [ΔT:] = (Tl ) (TR) between the target set temperature [Te3 and the cabin temperature [TR] (207
). Next, failure detection regarding the cooler and heater functions is performed using the deviation [ΔT]. Heater function. When the cooler function and the temperature control door 142 are functioning normally, each failure detection counter provided in the memory of the microcomputer 22, which is counted by a time interrupt to be described later, is activated in the failure diagnosis process of the main routine. Clear in step (208). If the abnormal state continues and the counter is no longer cleared, when the counter reaches a predetermined value, it is assumed that the corresponding function has failed, and a corresponding failure flag is set in the memory in the microcomputer 22. FIG. 8 is a detailed flowchart of step (208) in FIG. First, it is determined whether the absolute value of the difference between the temperature control door target voltage and the actually detected voltage is less than a predetermined value ΔQ208-1), and when it is normal and less than the predetermined value, a temperature control door failure is detected. Clear the counter for (20
8-2). Also, it is necessary to judge whether the difference between the target set temperature and the inside air temperature is less than or equal to the predetermined value ΔT 208-3
), when normal is below a predetermined value, a counter for heater failure detection is cleared (20B-4). Also, it is necessary to determine whether the control signal X is in the cooler region (X<0) 208-5
), when in the heater region (X > 0), clear the cooler failure detection counter 208-8), while in the cooler region (X < 0), further clear the counter between the target set temperature and the inside air temperature. It is necessary to judge whether the difference is greater than or equal to the predetermined value 217 208
-6), when 217 or more is normal, the cooler failure detection counter is cleared (208-7). In addition, in the step (208-9) of the failure display process, if any failure detection flag is set in the memory of the microcomputer 22, the failure indication lamp 34 of the operation section 3 is turned on, and the driver Inform. The count of the above failure detection counter is performed by the failure detection counter process (227) shown in FIG. 9, which is executed at a constant cycle.
Let's do it. When the temperature control door failure detection counter is counted up (227-1), and the temperature control door failure detection counter reaches a number corresponding to the elapse of a predetermined time (for example, 10 seconds) (227-2), the temperature control door failure detection is performed. A flag is set in the memory of the microcomputer 22 (227-3). Also, the counter for heater failure detection is counted up.227 4) The counter for heater failure detection is
For example, when the number corresponding to the elapsed time (20 minutes) is reached (227
5), Heater failure detection 7 uyt microcomputer 2
2 (227-6). Also, Ku2
Count up the failure detection counter 227-7)
, the cooler failure detection counter is set for a predetermined period of time (for example, 20
(227-8), a cooler failure detection flag is set in the memory of the microcomputer 22 (227-9). Furthermore, returning to Figure 3, (X]=k CΔT]+
A PI calculation of 1/τf[Δ'l')dt is performed. First, the integral term in the above equation calculates the temperature deviation [
ΔT] ((209).Furthermore, the control signal (X) is calculated by adding k[ΔT)t- to this integral term (210). In the above equation, τ is a constant determined by the control system (details of the above PI calculation process can be found in Japanese Patent Application No. 55-5783).
(as shown in No. 6). Further, when a dehumidification operation is performed by the dehumidification switch 32, a temporary correction value [ΔX] is added as the final process in step (210), and the value is set as the corrected value. This dehumidification operation will be described later. The control signal (X) generated in this way has an amount corresponding to the amount of heat required as the cabin heat load in the process of controlling the cabin temperature TR to the target set temperature T1, and in this example, k>0
．． Since τ〉0 is selected, the heating power is
Moreover, the larger the [X] value, the greater the heating power.
[X] <0 means that a cooling power is required, and the larger the [-X] value is, the greater the cooling power is required as the cabin heat load. The operation of this air conditioner based on the value of this control signal [X] will be explained with reference to FIG. 10. FIG. 10 is a diagram explaining the operation of the heat exchanger 1 in FIG. 1, and the horizontal axis represents the control signal [X].
This is an indication. First, temperature control door target voltage [VT
o) by calculation (211). This target voltage (V
TO] is a linear expression regarding [X], and [X] is [0
], [Vro) = [:Vtt:l], and with a predetermined positive value of [X] [X3], (VTO) =
(VtP). Here, (VTI) indicates that the temperature control door 142 is connected to the heater core 14.
LCVTz) corresponds to the voltage by the potentiometer 147 when the passage to heater core 141 is closed (θ is maximum) and when the passage to heater core 141 is completely open (θ-0
) corresponds to the voltage generated by the potentiometer 147. Next, in the interrupt processing routine, the voltage VT from the potentiometer 147 is read as a position signal of the temperature control door 142, and converted into a digital value [VT] by the A-D converter 21 (222). Next, the position of the temperature control door 142 is controlled by comparing the target voltage (VTO) and (VT) (223). That is, first, [ΔVT:]-[VTO]CVTI
For the predetermined value [ΔVTp]) 0, [ΔVT
The control signal [TI] becomes “0” when I<(ΔVTP:], and 1″ when [−ΔVTP)≦[ΔVT)≦[Δ■τP]”
, a control signal [T2] that becomes 0'' in a range other than the above is generated. When the control signals [Tl] and [T2] are 1'', the switch elements 233 and 234 are not turned on, and the solenoid valve 143. 144 is energized, and is not energized when it is '0''. By the above operation, as described above, [ΔVt
)> [ΔVtp], the temperature control door 142 is rotated in the direction in which θ increases, and in [ΔVT:l<[knee ΔV T P ], the temperature control door 142 is rotated in the direction in which θ is decreased. Also,
In the range of [-ΔVtp]≦[ΔVT)≦[ΔVtp:l, the temperature control door 142 is in a stationary state, and the position θ of the temperature control door 142 at this time is the target voltage (VTO) corresponding to the control signal [X]. It is in a position corresponding to . Next, return to step (215) of the main routine,
The target temperature of the discharge air temperature Tc (Tco:le is determined by In the range of [X]≧[X2], [X
) = (X 2 ] in [:'I'(!1), [X
) = (0) and the predetermined value [Tc2) (25C in this example)
This is the value determined by the linear equation connecting the two points. In addition, [X]=

Near [0], the cabin heat load is a region where neither heating power nor cooling power is required, and the outside air temperature To is close to the target set temperature T8. In this region, since there is almost no need to operate the cooling means, [Tc2] and [T6] are set. In the next step (216), the target source of discharge air temperature [
Compare [Tco] and the discharge air temperature ('rc), calculate the temperature difference [ΔTc) - [Tco][Tc], and use the value of [ΔTc] to set the compressor control signal [
C]. That is, [ΔTc]≧

At [0], [C] is 0”, [ΔTc]

At [0], [C] becomes ``1''. When the compressor control signal [C] is 1'', the switch element 235 is turned on at step (218), and the compressor relay 132b is energized. Then, when the compressor relay 132b is turned on, the magnetic clutch 132a is excited, the compressor 132 is operated, and the air passing through the evaporator 131 is cooled to lower the discharge air temperature Tc. As the discharge air temperature Tc decreases, [ΔTc)≧

[0] becomes [C) - [0']. Therefore, at the final step (218) of the main routine, compressor 132 is deactivated. In this way, by repeatedly operating and non-operating the compressor 132, the discharge air temperature Tc is changed by the control signal [Xl
The temperature is maintained close to the target temperature (Tco) determined by However, as described above, in the range of [X]≧0, the cabin heat load requires heating power, so that the target set temperature T8 > the cabin outside air temperature To, and on the other hand, Tco > T c2 * T
s, and since the suction port door 111 sucks in air outside the cabin, the temperature of the air sent to the evaporator 131 is the outside air temperature T. Close to. Therefore, even if the cooling means does not operate, [ΔT
c)) If 0, the compressor 132 will not operate. Then, it becomes [Te3]. The blower air volume A is the voltage Vy supplied to the motor 123.
is approximately proportional to Voltage V supplied to this motor 123
F is controlled as follows. First, calculate the target voltage (VF:) corresponding to the control signal [X]. Also, for the predetermined negative value [Xl] and positive value [I4] of [X], [X)≦ [Xl ), [:X:l≧[X4
] at the maximum value (VFI3 (12V in this example), the above negative value [:X2], the positive value [X3] at the maximum value [Vyz:]
(4V in this embodiment). And (X+:]≦[
In the range of X]≦[X2], CXFI at [X1],
[X2] determines the linear equation (VP:] connecting the two points that become [Vy211], and [I3]≦[X]≦[I4]
In the range of [X3] (VF2) and [X4] [Vp
1], determine CVpE from the linear equation connecting the two points (2
17). The target value (Vr) requested above is set at step (218
) in the D-A converter 239 of the interface circuit 23.
This voltage VF is converted into an analog voltage VFI+.
motor 12 by driver 122 controlled by II.
The voltage VF applied to the motor 123 is controlled to drive the motor 123. Depending on the value of the control signal (X), VF
is the maximum, that is, the blower air volume A is the maximum
Between X and Nashi, [X1] and [X2], there is a prower style:
@: A decreases almost linearly from maximum AMAX to minimum A MIN, and between [X2] and [X3], the minimum A
between [X3] and [X4], the minimum A
increases linearly from M IN to maximum AMAX, [X
4] Above, the AMAI is continuously controlled to reach the maximum AMAI. In addition to the above operations, the suction port door 111 and mode door 151 are also controlled by the value of the control signal [X] during the process. That is, [X]≦

[0] is 1”, [X]≧

Control signal [:It:] becomes 0" when [0], "1" when [X]≦[X,]
, generates a control signal [X2] that becomes 0'' when [X]≧[X5] (212). Note that [I5] is a negative value and [:Xt:]<(Xs
]〈[X2]. When the control signals Crt], [L+) are 1'',
In step (218), the switch elements 231 and 232 are turned on and the solenoid valves 114 and 115 are energized, and when the value is 0'', the solenoid valves 114 and 115 are not energized.The control signal (X) is [X]≦[X6 ], as described above, both [It) and [:I2'] become 1'', the solenoid valves 114 and 115 are energized, and the suction door 11
1, the actuator 112 is in a state in which internal air is sucked. [X]≧

When [0], CI+: ], (I2)
Both are O", and the suction door 111 is pulled by the return spring 113 and enters the state of sucking outside air. [X5]≦(X)≦

At [0], [Work 1] is 1”, [■
2] is 0'', the suction door 111 is in the intermediate position and is in a state of sucking inside and outside air. Similarly, the mode door 151 is also controlled by the value of the control signal [X]. ,

[0]〈[X6]＜ (X 7
) < CX s ), [I7)
is predetermined. [X] The control signal [0!] increases to "1" at [X7] and 0 at EXE≧[X7], and '1'' at [X] and [X6],
Creates a control signal [02] that becomes '0'' when [X]≧[X6] (213). Then, depending on the values of the control signals [:Ot) and (Ox), the mode door 151 performs the next step (218) iC. When CX ) < (X a ), the control signal (0+1
[02] are both ``'1'', switch element 236
．． 237 are both turned on, the solenoid valves 153 and 154 are energized, and the mode door 151 is brought into an upward blowing state by the actuator 152. In addition, in [X]>[X7], both (Ol) and (02) are "0", the solenoid valves 153 and 154 are not energized, and the mode door 151 is in the downward blowing state due to the return spring 155. In [X6]≦(X)≦[X7], [ol] is “1”
, [02] becomes IO", so the solenoid valve 153 is energized, and the solenoid valve 154 is not energized, so the mode door 15
1 is the intermediate position, which means that the air is blown upward and downward. According to the embodiment of the present invention described above, the target voltage indicating the target position of the temperature control door 142 and the actual If the absolute value of the difference between the voltage indicating the position of The next failure can be prevented from occurring. [Effects of the Invention] As explained above, according to the present invention, it is possible to detect a failure of the temperature control door, so there is an effect that the occurrence of a secondary failure can be prevented.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an automotive air conditioner according to 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 example of the operation of the control unit shown in FIG.
Fig. 5 is a circuit diagram showing an embodiment of the temperature sensor voltage detector shown in Fig. 1, Fig. 6 is a characteristic diagram of the temperature sensor, and Fig. 7 is a circuit diagram showing an embodiment of the temperature sensor voltage detection section of Fig. 1.
A flowchart showing details of step (204) in the figure;
8 is a flowchart showing details of step (208) in FIG. 3, FIG. 9 is a flowchart showing details of step (227) in FIG. 4, and FIG. 10 is an explanation of the operation of the heat exchange section in FIG. 1. It is a line diagram. 1... Heat exchange section, 2... Control section, 3... Operation section,
21... A-D converter, 22... Microphone computer, 23... Interface circuit, 24... Comparison circuit, 31... Temperature setting device, 34... Fault indicator lamp, 100 ...Heat exchange unit case, 103
...Bypass, 111...Suction door, 121...
・Blower 1131... Evaporator, 141... Heater core, 142... Temperature control door, 147... Potentiometer, 151... Mode door, 160... Discharge air temperature sensor, 170... Vehicle interior temperature sensor. Agent Patent Attorney Akio Takahashi No. 1, No. 2, No. 3, Li No. 1

Claims (1)

[Claims] 1. Cooling means, heating means, and cabin temperature sensor. Electric signals from an outside air temperature sensor and a potentiometer linked to the temperature control door are received via an A-D converter to control the temperature control door according to the difference between the cabin temperature and the target set temperature. Equipped with a microcomputer to
In the automotive air conditioner that automatically controls a vehicle interior temperature to the target set temperature, the microcomputer is configured to generate a voltage from a target voltage indicating a target position of the temperature control door and from the potentiometer indicating a controlled position of the temperature control door. The air conditioner for an automobile is characterized by comprising a failure detection means that determines that the temperature control door is malfunctioning when the absolute value of the difference between the applied voltage and the applied voltage is larger than a predetermined value, and displays the failure on a failure display means. harmonization device.