JPH06307722A - Air-conditioning equipment for vehicle - Google Patents

Abstract

PURPOSE:To obtain air-conditioning equipment for a vehicle which enables stable prevention of freezing and can be handled easily. CONSTITUTION:A pressure sensor 10 as a pressure detecting means for detecting a refrigerant pressure of a refrigerant circuit 1 is interposed between a motor- operated compressor 2 and an evaporator 4 being the low-pressure side of the refrigerant circuit 1. The pressure sensor 10 detects the refrigerant pressure on the low-pressure side of the refrigerant circuit 1 and outputs a pressure detection signal S3 to a controller 8. The controller 8 outputs a control signal S2 in accordance with the pressure detection signal S3 to an inverter 9. Based on a prescribed pressure threshold set to be higher than a freezing start pressure value at which freezing starts in the evaporator 4, the controller 8 controls the inverter 9 for the prescribed pressure threshold when a pressure value corresponding to the pressure detection signal S3 lowers below this prescribed pressure threshold, and therefore frosting is prevented without fail before the freezing in the evaporator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner mounted on a vehicle such as an electric vehicle and equipped with an electric compressor.

[0002]

2. Description of the Related Art Conventionally, in this type of vehicle air conditioner, in order to prevent the formation of frost on the evaporator 4 in the refrigerant circuit 1, FIG.
As shown in FIG. 3, there is one in which a temperature sensor 7 as a temperature detecting means is provided near the outlet of the evaporator 4. The temperature detection signal S1 detected by the temperature sensor 7 is sent to the controller 8
The controller 8 outputs the control signal S2 corresponding to the temperature detection signal S1 to the inverter 9. As a result, the rotation speed of the electric compressor 2 is adjusted by the inverter 9. The refrigerant circuit 1 includes a condenser 3, a receiver dryer 5, and an expansion valve 6, which are connected in series via a pipe. The electric compressor 2 has an electric motor that is a drive unit and a compression operation unit that is a driven unit housed in a casing.

In this refrigerant circuit 1, an electric compressor 2
Compresses the low-pressure vapor-phase refrigerant flowing from the evaporator 4 and sends it to the condenser 3 as a high-pressure vapor-phase refrigerant. The high-pressure gas-phase refrigerant is radiatively condensed by the condenser 3, becomes a high-pressure gas-liquid mixed-phase refrigerant and flows into the receiver dryer 5, where it is separated into a gas phase and a liquid phase, and only the liquid phase is passed to the expansion valve 6. Inflow. When passing through the expansion valve 6, the refrigerant changes from the high pressure liquid phase to the low pressure gas-liquid mixed phase due to the throttling effect of the expansion valve 6. The low-pressure gas-liquid mixed-phase refrigerant that has passed through the expansion valve 6 flows into the evaporator 4. In the evaporator 4, the low-pressure gas-liquid mixed-phase refrigerant absorbs heat, becomes a low-pressure gas-phase refrigerant, and returns to the electric compressor 2. With the operation of the air conditioner, the refrigerant makes a phase transition while moving in the refrigerant circuit 1 as indicated by an arrow M. Such refrigerant phase transition is repeated during the operation of the air conditioner.

In the refrigerant circuit 1, since the controller 8 constantly controls the rotation speed of the electric compressor 2 in the inverter 9 in accordance with the temperature detection of the temperature sensor 7 described above, the surface of the evaporator 4 is not affected. Freezing (frosting) of the attached condensed water is prevented.

[0005]

In the vehicle air conditioner described above, the controller 8 controls the rotation speed of the electric compressor 2 in the inverter 9 in accordance with the temperature detection from the temperature sensor 7. However, if the mounting position of the temperature sensor 7 is different, or if the ventilation amount near the outlet of the evaporator 4 varies depending on the usage environment, erroneous detection is often made and an inappropriate control command is given to the inverter 9. Sometimes. In such a case, the rotation speed of the electric compressor 2 cannot sufficiently prevent freezing, and as a result, the surface of the evaporator 4 freezes and the heat exchange function is impaired.

In other words, according to the conventional vehicular air-conditioning system, the installation location where the installation of the temperature sensor 7 can be accurately detected within the area to be used is selected, and the temperature sensor 7 is installed accurately at the installation location. There is a risk of false positives unless you do so.
Here, the accurate installation of the temperature sensor 7 is a complicated task for the installer, and the handling must be done with great care.

The present invention has been made to solve the above problems, and a technical problem thereof is to provide a vehicle air conditioner which can stably prevent freezing and can be easily handled.

[0008]

According to the present invention, in a vehicle air conditioner including a refrigerant circuit including an electric compressor whose rotation speed is adjusted by an inverter, the low pressure side refrigerant pressure of the refrigerant circuit is detected. There is obtained a vehicle air conditioner including a pressure detection unit that outputs a pressure detection signal and a controller that controls an inverter based on the pressure detection signal.

Further, according to the present invention, in the above vehicle air conditioner, the refrigerant circuit further includes an evaporator, and the controller is based on a predetermined pressure threshold value higher than a freezing start pressure value at which the freezing of the evaporator starts. When the pressure value according to the pressure detection signal falls below the predetermined pressure threshold value, the vehicle air conditioner is obtained in which the inverter is controlled so as to follow the predetermined pressure threshold value and the rotation speed of the electric compressor is adjusted.

[0010]

The air conditioner for a vehicle of the present invention will be described in detail below with reference to the accompanying drawings. Figure 1
1 shows a basic configuration of a vehicle air conditioner according to an embodiment of the present invention. Since this vehicle air conditioner also has basically the same configuration as the vehicle air conditioner shown in FIG. 3, the same components are designated by the same reference numerals and only different portions will be described.

In this vehicle air conditioner, a pressure sensor 10 as pressure detecting means for detecting the refrigerant pressure in the refrigerant circuit 1 between the low pressure side of the refrigerant circuit 1, that is, between the electric compressor 2 and the evaporator 4. Is installed. The pressure sensor 10 is
The pressure detection signal S by detecting the low pressure side refrigerant pressure of the refrigerant circuit 1
3 is output to the controller 8. In the controller 8,
The inverter 9 outputs the control signal S2 corresponding to the pressure detection signal S3.
Output to.

That is, in this vehicle air conditioner, the rotation speed of the electric compressor 2 in the inverter 9 is constantly controlled by the controller 8 in response to the pressure detected by the pressure sensor 10 to prevent frost formation on the surface of the evaporator 4. . This pressure sensor 1
Since 0 is directly provided in the pipe between the electric compressor 2 and the evaporator 4 in the refrigerant circuit 1, the refrigerant pressure having a high correlation with the heat exchange characteristics of the evaporator 4 is detected and then the frost is appropriately formed. Can be prevented.

FIG. 2 shows a control characteristic showing the relationship of the refrigerant pressure detection value (P) with respect to the time (t) transition in the controller 8. Here, based on the predetermined pressure threshold P _S set higher than the freezing start pressure value P _X at which the controller 8 actually starts freezing in the evaporator 4, the pressure value corresponding to the pressure detection signal S3 is a predetermined pressure threshold. P
It shows that the inverter 9 is controlled so as to follow the predetermined pressure threshold value P _S when the value falls below _S. According to this configuration, since the controller 8 controls the inverter 9 based on the predetermined pressure threshold P _S corresponding to the pressure value before the evaporator 4 freezes, frost formation is reliably prevented.

[0014]

As described above, according to the vehicle air conditioner of the present invention, the pressure detecting means for detecting the refrigerant pressure having a high correlation with the heat exchange characteristic is provided on the low pressure side of the refrigerant circuit, and the pressure is detected by the controller. Since the control of the rotation speed adjustment of the electric compressor in the inverter is performed according to the pressure detection from the detection means, frost formation can be reliably prevented. Further, according to this vehicle air conditioner, the controller sets a predetermined pressure threshold value higher than the freezing start pressure value at which the evaporator starts freezing, and the inverter is controlled so as to follow the predetermined pressure threshold value. Therefore, prevention of freezing of the evaporator can be properly achieved before freezing. Furthermore, in this vehicle air conditioner, the pressure detection means is provided integrally with the refrigerant circuit, so that the installation and handling thereof are simplified.

[Brief description of drawings]

FIG. 1 shows a basic configuration of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 shows control characteristics of a controller provided in the vehicle air conditioner shown in FIG.

FIG. 3 shows the basic configuration of a conventional vehicle air conditioner.

[Explanation of symbols]

 1 Refrigerant Circuit 2 Electric Compressor 4 Evaporator 5 Receiver Dryer 6 Expansion Valve 7 Temperature Sensor 8 Controller 9 Inverter 10 Pressure Sensor

Claims (2)

[Claims] 1. A vehicle air conditioner comprising a refrigerant circuit including an electric compressor whose rotation speed is adjusted by an inverter, and pressure detection means for detecting a low pressure side refrigerant pressure of the refrigerant circuit and outputting a pressure detection signal. And a controller that controls the inverter according to the pressure detection signal. 2. The vehicle air conditioner according to claim 1, wherein the refrigerant circuit further includes an evaporator, and the controller is based on a predetermined pressure threshold value higher than a freezing start pressure value at which freezing of the evaporator begins. When the pressure value according to the pressure detection signal falls below the predetermined pressure threshold value, the inverter is controlled so as to follow the predetermined pressure threshold value, and the rotation speed of the electric compressor is adjusted. A vehicle air conditioner.