JP2003021410A - Vehicle air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately make a heat exchanger on the vehicle interior side demonstrate its cooling capacity. SOLUTION: When a pressure value detected by a pressure detecting means 6 reaches a reference pressure not higher than a limit pressure for interrupting the compressor 1, air volume by a vehicle exterior blower 7 to a heat exchanger 2 on the vehicle exterior side is increased by a control means 5.

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.

[0002]

2. Description of the Related Art Conventionally, as a vehicle air conditioner, the temperature of a refrigerant flowing through a condenser outlet side high pressure passage from a condenser outlet side of a refrigeration cycle to an inlet side of a pressure reducing valve is detected,
There is a method in which the optimum pressure of the refrigerant flowing through the high-pressure passage is calculated from this refrigerant temperature to determine whether the actual high-pressure pressure in the high-pressure passage is higher than the optimum high pressure (Japanese Patent Laid-Open No. 7-294033). ).

[0003]

However, in the above-described conventional vehicle air conditioner, although the coefficient of performance of the refrigeration cycle is improved, the high-pressure side pressure becomes extremely high when the outside air temperature is high. Therefore, even if the high-pressure side pressure becomes extremely high, it is necessary to have sufficient pressure resistance performance that will not cause damage. Such a structure having excellent pressure resistance has a problem of being expensive and having a large weight.

Therefore, according to the present invention, a vehicle in which the cooling capacity of the heat exchanger inside the vehicle can be appropriately exhibited even in a situation where the outside air temperature is high and the refrigerant pressure on the high pressure side of the outlet of the compressor is likely to rise. An object of the present invention is to provide an air conditioner for use.

[0005]

Means for Solving the Problems The present invention, as means for solving the above problems, radiates a refrigerant discharged from a compressor by a heat exchanger outside a vehicle and reduces the pressure by a pressure reducing valve.
After vaporizing with a heat exchanger inside the car that has a blower for outside the car,
In a vehicle air conditioner equipped with a refrigeration cycle for returning to the compressor for circulation, pressure detection means for detecting the refrigerant pressure on the outlet high pressure side of the compressor, and pressure detected by the pressure detection means are limit pressures for stopping the compressor. If the reference pressure is less than, the control means for increasing the amount of air blown to the vehicle exterior heat exchanger by the vehicle exterior blower is provided.

With this configuration, the amount of air blown by the exterior blower increases before the compressor stops, and the amount of heat released from the refrigerant in the exterior heat exchanger increases. As a result, the pressure of the refrigerant on the high pressure side of the outlet of the compressor is reduced, and the compressor is prevented from stopping. Therefore, it becomes possible to continue the circulation of the refrigerant in the refrigeration cycle and maintain the cooling by the in-vehicle heat exchanger.

When the pressure detected by the pressure detecting means becomes the second reference pressure which is equal to or lower than the limit pressure and exceeds the reference pressure by the control means, the opening degree of the pressure reducing valve is corrected upward, Further, it is preferable in that the rise of the refrigerant pressure on the high pressure side of the outlet of the compressor can be suppressed.

CO ₂ can be used as the refrigerant.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a refrigeration cycle C of a vehicle air conditioner according to this embodiment. In the refrigeration cycle C, the refrigerant discharged from the compressor 1 (here, CO ₂ is used) returns to the compressor 1 via the vehicle exterior heat exchanger 2, the pressure reducing valve 3, and the vehicle interior heat exchanger 4. Circulate.
The control device 5 drives and controls the compressor 1, the pressure reducing valve 3, and an outside vehicle blower 7, which will be described later.

The compressor 1 can be driven by the power of an engine (not shown). A pressure sensor 6 is provided on the outlet side pipe of the compressor 1.

The exterior heat exchanger 2 is arranged in the front part of the vehicle and has a conventionally well-known structure suitable for radiating the refrigerant. The exterior heat exchanger 2 includes an exterior blower 7. The blower 7 for outside the vehicle can change the amount of air blown, and the amount of heat released from the refrigerant in the vehicle exterior heat exchanger 2 (heat exchange efficiency) can be adjusted by changing the amount of blown air. An outside air sensor 8 for detecting the outside air temperature is provided near the outside heat exchanger 2.

The pressure reducing valve 3 can be changed by changing the opening degree.
The refrigerant pressure on the upstream side is adjusted and the refrigerant passing therethrough is depressurized.

The in-vehicle heat exchanger 4 is arranged in the air conditioning unit 9 at the front of the vehicle and has a conventionally known structure for cooling and dehumidifying the air passing through the air conditioning unit 9. The vehicle interior heat exchanger 4 is provided with a temperature sensor 10 for detecting the temperature of the surface or the vicinity thereof. Air conditioning unit 9
A blower 12 that is rotated by the drive of a blower motor 11 is disposed on the upstream side of the vehicle interior heat exchanger 4, and blows the inside air or the outside air into the vehicle with a predetermined air volume. In addition, the air conditioning unit 9
The air mix door 13 is provided on the downstream side of the heat exchanger 4 inside the vehicle.
Is rotatably provided to divert the cool air and direct one of them to the heater core 14. The amount of air heated by the heater core 14, that is, the ratio of the cold air to the hot air to be mixed is changed depending on the rotating position (opening) of the air mix door 13.
The air is blown into the car at the desired temperature.

The control device 5, based on the values detected by the temperature sensor 10 and the pressure sensor 6 and the like, drives the compressor 1 at a rotational speed, the pressure reducing valve 3 and the outside blower 7 as described below. Alternatively, the rotation position of the air mix door 13 is adjusted.

Next, the operation of the vehicle air conditioner having the above-mentioned structure will be described with reference to the flow chart shown in FIG.

First, the pressure Ph detected by the pressure sensor 6 is read (step S1), and it is judged whether or not the detected pressure Ph is larger than the first reference pressure Ph1 (step S1).
2). The first reference pressure Ph1 has a limit pressure Pmax (for example, 15 MPa) at which the compressor 1 must be stopped.
Use a value less than. As shown in the Mollier diagram of FIG. 3, the first reference pressure Ph1 is a high pressure (shown by a curve T) that maximizes energy consumption efficiency (COP) with respect to the refrigerant temperature on the inlet side of the pressure reducing valve 3. Based on this, it is determined as follows. That is, as the refrigerant pressure increases, the power consumption of the compressor 1 increases. Further, it is considered that the outside air temperature rarely exceeds 40 ° C in Japan. Therefore, in the curve T, the refrigerant pressure (10.2 MPa) when the outside air temperature is 40 ° C. is set as the first reference pressure Ph1 (this condition can be freely set). This makes it possible to determine the drive timing of the exterior blower 7 while considering the outside air temperature and minimizing the power consumption of the compressor 1.

When the detected pressure Ph becomes larger than the first reference pressure Ph1, the amount of air blown by the exterior blower 7 is increased by a predetermined amount (step S3). As a result, the heat exchange efficiency in the vehicle exterior heat exchanger 2 can be promoted, and the pressure detected by the pressure sensor 6 can be reduced.
After that, if the detected pressure Ph becomes higher than the first reference pressure Ph1, the flow returns to step S3 each time, and the blown air amount is increased stepwise.

When the amount of blown air reaches the maximum value (step S4), the heat exchange efficiency in the exterior heat exchanger 2 cannot be increased any more, and thus the opening degree of the pressure reducing valve 3 is set to a predetermined amount. Only (step S5). This allows
It is possible to reduce the detected pressure Ph. And
When the detected pressure Ph becomes larger than the second reference pressure Ph2 (step S6), the process returns to step S6 each time and the opening degree of the pressure reducing valve 3 is successively increased. Second reference pressure Ph2
Is less than the limit pressure Pmax, the first reference pressure Ph1
A larger value, specifically, a value considering the control delay from the limit pressure Pmax (for example, 15 MPa-α (a value in consideration of safety of the control section: for example, α = 0.5 MPa)) is used.

After that, when the opening degree of the pressure reducing valve 3 reaches the maximum value and the detected pressure Ph reaches the limit pressure Pmax (step S7), the driving of the compressor 1 is stopped (step S8).

As described above, before the refrigerant pressure on the high pressure side of the outlet of the compressor 1 reaches the limit pressure Pmax at which the compressor 1 must be stopped, the amount of air blown by the exterior blower 7 and then the opening degree of the pressure reducing valve 3. I adjusted it, so
It is possible to suppress an increase in the refrigerant pressure and maintain the cooling capacity of the vehicle interior heat exchanger 4.

[0022]

As is apparent from the above description, according to the present invention, when the detected pressure becomes the reference pressure below the limit pressure for stopping the compressor, the amount of air blown to the outside heat exchanger by the outside blower. As a result, the heat dissipation of the refrigerant is promoted and the rise of the refrigerant pressure is suppressed,
By reducing the number of times the compressor is stopped, the cooling capacity of the heat exchanger inside the vehicle can be fully exerted.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a refrigeration cycle of a vehicle air conditioner according to the present embodiment.

FIG. 2 is a flowchart showing air conditioning control according to the present embodiment.

FIG. 3 is a Mollier diagram showing the refrigeration cycle according to the present embodiment.

[Explanation of symbols]

1 ... Compressor 2 ... Exterior heat exchanger 3 ... Pressure reducing valve 4 Heat exchanger inside the car 5 ... Control device 6 ... Pressure sensor 7 ... Exterior blower 8 ... Outside air sensor 9 ... Air conditioning unit 10 ... Temperature sensor 11 ... Blower motor 12 ... Blower 13 ... Air mix door 14 ... Heater core

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B60H 1/32 626 B60H 1/32 626E (72) Inventor Shinji Watanabe No. 3 Yoshikawa Industrial Park, Higashihiroshima City, Hiroshima Prefecture No. 11 Stock Company Japan Climate Systems

Claims (3)

[Claims] 1. A refrigerant discharged from a compressor is radiated by an exterior heat exchanger, decompressed by a pressure reducing valve, vaporized by an interior heat exchanger having an exterior blower, and then returned to the compressor for circulation. In a vehicle air conditioner equipped with a refrigeration cycle, pressure detection means for detecting the refrigerant pressure on the outlet high pressure side of the compressor, and pressure detected by the pressure detection means should be a reference pressure less than a limit pressure for stopping the compressor. For example, the vehicle air conditioner is provided with a control means for increasing the amount of air blown to the vehicle exterior heat exchanger by the vehicle exterior blower. 2. The control means upwardly corrects the opening of the pressure reducing valve when the pressure detected by the pressure detecting means becomes a second reference pressure that is equal to or lower than the limit pressure and exceeds the reference pressure. The vehicle air conditioner according to claim 1, wherein: 3. The vehicle air conditioner according to claim 1, wherein the refrigerant is CO ₂ .