JPH07215049A - Air conditioning control method for vehicle - Google Patents

Abstract

PURPOSE:To perform desired air conditioning control in an air conditioning control method for vehicle in which a compressor is controlled based on the detected temperature at an evaporation sensor, by estimating the degree of freezing based on the ratio the impressed voltage to the current-carrying value to a blower so as to control the compressor, even if a trouble is generated in the evaporation sensor. CONSTITUTION:The impressed voltage and the current value of the blower motor 4 of a blast unit 1 are detected by a control device 5, and air passing through an evaporator 6 is cooled and dehumidified by circulating and gasifying refrigerant by means of a compressor 7 in the evaporator. An evaporation sensor 8 is fitted to the evaporator 6, the detected temperature is computed by the change of the resistance value, and the compressor 7 is control led to be ON/OFF so as to circulate the refrigerant. When the trouble of the evaporation sensor 8 is detected, it is estimated whether it is in the lock condition or not based on the impressed voltage and the current value, and when freezing is estimated, it is judged that the evaporator is frozen so as to be unable to send air, and the compressor is drivingly controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air-conditioning control method, and more particularly to a vehicle air-conditioning control method capable of performing appropriate air-conditioning control even if an EVA sensor fails.

[0002]

2. Description of the Related Art Conventionally, in vehicle air-conditioning control, when the temperature detected by an evaporator sensor provided in the vicinity of the evaporator falls below a predetermined value, the compressor is stopped to prevent the evaporator from freezing.

In such air-conditioning control, if the evaporator sensor fails, cooling in the evaporator becomes excessive,
Condensed water on the surface of the evaporator freezes and hinders the passage of air. As a result, a desired air flow rate may not be obtained. Therefore, if the evaporator sensor fails, it is generally performed to stop the drive of the compressor even in any air-conditioning condition to prevent the evaporator from freezing.

[0004]

However, when the EVA sensor fails, as described above, there is a problem in that appropriate air conditioning cannot be performed until the EVA sensor is repaired by taking measures to stop the compressor. The present invention has been made in view of the above problems, and an object thereof is to provide a vehicle air conditioning control method capable of performing desired air conditioning control even when the EVA sensor fails.

[0005]

In order to achieve the above object, the present invention drives a blower motor to rotate a sirocco fan to suck inside air or outside air sucked into a blower unit, and a compressor to drive a refrigerant. When cooling and dehumidifying by blowing air to the circulated evaporator, drive control of the compressor is performed based on the temperature detected by an evaporator sensor attached to the evaporator,
In a vehicle air conditioning control method for preventing freezing of the evaporator, if a failure of the evaporator sensor is detected, the degree of freezing in the evaporator based on the ratio of the applied voltage value to the blower motor and the current value at that time. Guess
The compressor is drive-controlled based on the degree of freezing.

Further, if a failure of the evaluation sensor is detected,
The freezing degree in the evaporator may be estimated based on the value of the electric current supplied to the blower motor, and the compressor may be drive-controlled based on the freezing degree.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a blower unit 1 provided in the front portion of the vehicle, and a damper 2 for selecting inside air or outside air is provided on the upstream side of the blower unit 1. A sirocco fan 3 is provided in the vicinity of the damper 2, and the inside air or the outside air is sucked into the blower unit 1 depending on the position of the damper 2. The sirocco fan 3 is rotated by driving the blower motor 4, and the voltage value applied to the blower motor 4 and the current value at that time are detected by the control device 5.

An evaporator 6 is arranged downstream of the sirocco fan 3 of the blower unit 1. Refrigerant circulates in the evaporator 6 by a compressor 7 which is drive-controlled by the controller 5. When the refrigerant vaporizes, heat is taken from the surroundings to cool and dehumidify the air passing through the evaporator 6.

An evaporator sensor 8 composed of a thermistor or the like is attached to the evaporator 6. EVA sensor 8
Since the resistance value of 1 changes depending on the ambient temperature, the control device 5 detects the change in resistance value as a voltage value and calculates the detected temperature based on the detected voltage value.

The control device 5 controls the ON / OFF of the compressor 7 as follows. That is, if the evaporator sensor 8 is in a normal state without a failure, the compressor 7 is controlled to be turned on / off and the refrigerant is circulated in the evaporator 6. In this case, it is preferable to change the on / off ratio of the compressor 7 according to the degree of freezing of the evaporator 6. For example, when the evaporator 6 is not frozen, the freezing degree is 0%, and when the air cannot pass due to freezing, the freezing degree is 100%, and the on / off ratio of the compressor 7 is linear between 0% and 100%. You can change it.

If a failure of the evaporator sensor 8 is detected, the degree of freezing in the evaporator 6 is estimated and the compressor 7 is turned on / off as follows. In this case, the failure of the evaluation sensor 8 can be easily detected because the detection voltage is maintained at a constant high value due to the disconnection.

The degree of freezing in the evaporator 6 is estimated based on the voltage value (blower voltage value V) applied to the blower motor 4 and the current value (blower current value I) detected at that time. In this case, it is also inferred whether the blower motor 4 is in the locked state.

These assumptions are divided with V = 5 / 4I (V; blower voltage value, I; blower current value) and V = 19 / 12I as boundaries, for example, as shown in the graph of FIG. It can be carried out depending on which of the three regions the detected blower voltage value and blower current value are located (first, second abnormal region and normal region in the figure).

That is, the ratio of both detected values a = I / V is a>
In the case of 19/12, for example, it is estimated that the blower motor 4 is in the locked state (first abnormal area), and in the case of 5/4 <a <19/12, it is estimated that it is in the normal state (normal area). ), A <5 /
In the case of 4, it is presumed that, for example, the evaporator 6 is frozen and cannot blow air (second abnormal region).

When the degree of freezing of the evaporator 6 is estimated in this way, the drive control of the compressor 7 is performed based on the estimated value in the same manner as when the evaporator sensor 8 is operating normally.

Specifically, for example, the blower voltage value is 12V.
If the blower current value is up to 15 A, it is determined that the second abnormality is present, and the compressor 7 is maintained in the off state. Then, if the blower current value exceeds 15 A, the on time of the compressor 7 is gradually lengthened, and when it reaches 17 A, 1
00% ON state. Between 15A and 17A, if the on / off ratio of the compressor 7 is 50%,
After being turned on for 1 minute, it is turned off for 1 minute to perform on / off control in a cycle of 2 minutes. afterwards,
If it exceeds 17 A, the compressor 7 is maintained in a 100% ON state.

In the above embodiment, the ratio I / V of the voltage value V applied to the blower motor 4 and the current value I at that time is 5
It is judged that the compressor 7 is normal between / 4 and 19/12, the second abnormality when it is 5/4 or less, and the first abnormality when it is 19/12 or more, and the on / off control of the compressor 7 is performed. It may be set freely according to the rating of the blower motor 4 used.

Further, in the above-mentioned embodiment, the evaporator 6 is based on the relationship between the blower voltage value applied to the blower motor 4 and the blower current value at that time according to the graph of FIG.
Although the degree of freezing is detected and the on / off control of the compressor 7 is performed, it may be performed based on only the blower current value according to the graph of FIG.

Further, in the above embodiment, the compressor 7
The on / off control of was changed linearly,
You may make it carry out step by step. Specifically, as shown in FIG. 3, while the blower current value is 15 A to 17 A, the on / off ratio of the compressor 7 is maintained at 50%, and
If it becomes higher than 7 A, it may be maintained at 100%.

Furthermore, in the above embodiment, the lock of the blower motor 4 can be detected only when the evaporation sensor 8 fails, but it is preferable to detect this even when the evaporation sensor 8 is normal.

[0021]

As is apparent from the above description, the vehicle air conditioning control method according to the present invention makes it possible to detect the freezing degree of the evaporator from the relationship between the voltage value applied to the blower motor and the energization current value. The desired air conditioning control can be performed even if the evaluation sensor fails, and the occupant does not feel discomfort.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a vehicle air conditioner according to an embodiment.

FIG. 2 is a graph showing a relationship between a blower voltage value and a blower current value.

FIG. 3 is a graph showing on / off control of the compressor.

FIG. 4 is a graph showing a relationship between an evaporator frozen state and a blower current value according to another example.

[Explanation of symbols]

4 ... Blower motor, 5 ... Control device, 6 ... Evaporator,
7 ... Compressor, 8 ... EVA sensor.

Claims (2)

[Claims] 1. When cooling and dehumidifying the inside air or the outside air sucked into a blower unit by driving a blower motor and rotating a sirocco fan, by blowing the air to an evaporator in which a refrigerant is circulated by driving a compressor, Performing drive control of the compressor based on a temperature detected by an evaporator sensor attached to the evaporator,
In a vehicle air conditioning control method for preventing freezing of the evaporator, if a failure of the evaporator is detected, the degree of freezing in the evaporator based on the ratio of the voltage value applied to the blower motor and the current value at that time. And controlling the drive of the compressor based on the degree of freezing. 2. When cooling and dehumidifying by blowing the inside air or the outside air sucked into the blower unit by driving the blower motor to rotate the sirocco fan to the evaporator which drives the compressor and circulates the refrigerant, Performing drive control of the compressor based on the temperature detected by an evaporator sensor attached to the evaporator,
In a vehicle air conditioning control method for preventing freezing of the evaporator, if a failure of the evaporator is detected, the degree of freezing in the evaporator is estimated based on the current value to the blower motor, and the compressor is determined based on the degree of freezing. A vehicle air-conditioning control method comprising drive control.