JPH0456624A - Air conditioning device for automobile and control method thereof - Google Patents

Abstract

PURPOSE:To run a compressor at a low opening air temperature without the occurrence of seizure of a compressor due to a refrigerant too small in quantity by providing a means to run a variable capacity compressor in prior to a means to stop the variable capacity compressor through detection of a refrigerant pressure. CONSTITUTION:When air conditioning switch 14 is turned ON, an under-mentioned function is carried out by means of a controller 9. Namely, ON and OFF of a low pressure switch 8 is decided by a CPU 11 through the working of an AD converter 10. A magnet clutch 6 is turned ON through a compressor drive circuit 12 regardless of ON and OFF to run a variable capacity compressor 1. When the low pressure switch 8 is turned ON, processing of a delay is effected by means of the CPU 11 and a time lag is produced. When it is turned OFF, the magnet clutch 6 is turned OFF. Further, when the low pressure switch 8 is turned OFF, namely, an open air temperature is below 0 deg.C, by reducing a variable capacity condenser 2 to minimum capacity, an outlet refrigerant pressure is increased and the variable capacity compressor 1 is continuously run.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to intermittent control of a variable capacity compressor and control of refrigerant flow rate of a variable capacity condenser at low outside temperatures.

[Conventional technology]

As described in Japanese Unexamined Patent Publication No. 62-29856, the conventional device sets the set value of the refrigerant pressure switch that stops the compressor to 29-98 KPa (0, 3-1, 0k
g/cdG), allowing the compressor to operate even when the outside temperature was below 0°C.

[Problem to be solved by the invention]

The above conventional technology assumes that the compressor does not operate for a long time, and in the case of a variable capacity compressor, no consideration is given to the fact that it operates for a long time despite its small capacity, and refrigerant leaks especially during high heat loads such as summer. If
There were problems such as the compressor burning out.

An object of the present invention is to operate a compressor at low outside temperatures without causing seizure of the compressor due to insufficient refrigerant.

Another object of the present invention is to obtain the discharge refrigerant pressure of a variable capacity compressor necessary for capacity control of the variable capacity compressor by optimizing the refrigerant flow rate control of the variable capacity condenser. Means for Solving] In order to achieve the above object, a means for operating the variable capacity compressor is provided in preference to a means for detecting refrigerant pressure and stopping the variable capacity compressor.

Further, the variable capacity compressor operating means is provided with means for operating the variable capacity compressor based on the detected value of a refrigerant pressure sensor, a refrigerant temperature sensor, or both sensors on the outlet side of the variable capacity condenser. be.

Furthermore, means is provided for limiting the functional time of the variable capacity compressor operating means to a first predetermined value.

In order to achieve the above-mentioned other objects, a detection value of a refrigerant pressure sensor or a refrigerant temperature sensor or both of the sensors provided on the refrigerant outlet side of the variable capacity capacitor,
Alternatively, means is provided for opening and closing the refrigerant flow control valve of the variable capacity capacitor based on the temperature of the evaporator.

Further, the detected value of the refrigerant pressure sensor or the refrigerant temperature sensor or the value corresponding to the temperature of the evaporator is a fourth value.
The refrigerant flow control valve of the variable capacitor is closed when the refrigerant flow rate is less than a predetermined value.

[Effect]

The variable capacity compressor operating means operates the variable capacity compressor in priority to the means for detecting the refrigerant pressure and stopping the variable capacity compressor.
The variable capacity compressor can be operated even when the outside air temperature is low, when conventionally the variable capacity compressor stopping means would have stopped the variable capacity compressor.

Further, the variable capacity compressor is operated when the detected value of the refrigerant pressure sensor and the refrigerant temperature sensor provided on the outlet side of the variable capacity condenser, the vehicle interior temperature, and the evaporator temperature are equal to or higher than a second or third predetermined value. It is possible to prevent seizure of the variable capacity compressor due to operation with too little refrigerant.

Furthermore, the functional time of the variable displacement compressor operating means is limited to a first predetermined value. By setting the first predetermined value to the minimum time during which the variable capacity compressor can operate without refrigerant, failures such as seizure of the variable capacity compressor can be prevented.

Further, the refrigerant flow control valve of the variable capacitor is closed when a detected value of a refrigerant pressure sensor, a refrigerant temperature sensor, or both of the sensors provided on the refrigerant outlet side of the variable capacitor is equal to or lower than a fourth predetermined value. Since the valve is closed, the variable capacity condenser becomes the minimum capacity and the discharge refrigerant pressure of the variable capacity compressor can be increased.

At this time, the fourth predetermined value is set to a value corresponding to the discharge refrigerant pressure of the variable capacity compressor at which the variable capacity compressor becomes unable to control the capacity. The variable capacity compressor becomes capable of capacity control even under conditions where

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, the refrigeration cycle includes variable capacity compressor 1. Variable capacitor 2. It consists of an expansion valve 3° and an evaporator 4 connected to each other by refrigerant passages 5a', 5b, and 5c.

The magnetic clutch 6 transmits power from the vehicle engine (not shown) to the variable capacity compressor 1.
The refrigerant flow control valve 7 controls the capacity of the variable capacitor 2, and the low pressure switch 8 controls the refrigerant pressure to 2.1 kg/ci, which corresponds to the outside temperature of 0°C.
It is turned on when it is 0 or more, and turned off when it is less than 2.1 kg/aJG, and controls the operation and stop of the variable capacity compressor 1. The controller 9 controls the operation and stopping of the variable capacity compressor 1 and drives it, and includes an AD converter 10° CPU II, a compressor drive circuit 12 . It has a built-in memory 13, etc. The air conditioner switch 14 is
This selects whether to operate or stop the entire automobile air conditioner of this embodiment.

Details of the variable capacitor 2 will be explained with reference to FIGS. 2 and 3. In FIG. 2, the variable capacitor 2 has heat exchanger tubes 15 arranged in parallel and fins 16 between the heat exchanger tubes 15. Both ends of the heat transfer tube 15 are connected to an inlet ladder 17 and an outlet header 1 having a refrigerant passage therein.
8a and 18b, the inlet ladder 17 is provided with a refrigerant population 19, and the outlet ladder 18a and outlet header 18 are provided with a refrigerant population 19.
b are respectively connected to the refrigerant outlet 2o, and the ladder 1 is connected to the outlet.
A refrigerant flow control valve 7 is provided at the refrigerant outlet 20 connected to the refrigerant 8a.

When the refrigerant flow control valve 7 is open, the refrigerant flowing in from the refrigerant flow control valve 19 is supplied to both the A section and the B section heat transfer tubes 15, and when the refrigerant flow control valve 7 is closed, the refrigerant is supplied to the B section. heat exchanger tubes 15. That is, when the refrigerant flow control valve 7 is open, the capacity is maximum, and when it is closed, it is the minimum capacity.

Next, FIG. 3 shows that when the refrigerant flow control valve 7 is closed, refrigerant is supplied to the heat exchanger tubes 15 in both the A section and the B section, and when the refrigerant flow control valve 7 is open, the refrigerant is supplied to the heat exchanger tubes 15 only in the B section. supply.

That is, the maximum capacity is when the refrigerant flow control valve 7 is closed, and the minimum capacity is when it is open.The purpose is the same as that of the variable capacitor 2 in FIG. Either FIG. 2 or FIG. 3 may be used.

In addition, as shown in Fig. 4, the low pressure switch 8 turns off when the refrigerant pressure reaches a predetermined value P1 and turns on when the refrigerant pressure reaches a predetermined value P2. When the magnetic clutch 6 is lowered,
By cutting off the power to the variable capacity compressor 1 and stopping the variable capacity compressor 1, failures such as seizure of the variable capacity compressor 1 can be prevented.

Further, the predetermined value P1 is generally a refrigerant pressure of 206 KPa (2.1 kg/a #G) corresponding to an outside temperature of 0°C.

The functions of this embodiment will be explained with reference to FIG.

When the air conditioner switch 14 shown in FIG. 1 is turned on, the fifth
The controller 9 performs the functions shown in the chart 5TEPI to 5TEP(7)'7o in the figure.

In 5TEPI and 5TEP2, the low pressure switch 8 is turned on and off by the CPU 1 via the AD converter 1o.
The magnetic clutch 6 is turned on via the compressor drive circuit 12 regardless of whether it is on or off, and the variable capacity compressor 1 is operated.

In 5TEP3, when the low pressure switch 8 is off, the CPU II performs delay processing to generate a time delay, and the process moves to 5TEP4.

In 5TEP4, the CPU 11 monitors whether the low pressure switch 8 is turned on or off again via the AD converter 10, and when the low pressure switch 8 is turned off, the magnetic clutch 6 is turned off. Here, it is desirable that the delay processing time of 5TEP3 is set to a time that allows the variable capacity compressor 1 to operate without failure without refrigerant. Also, the 6th
As shown in the figure, when the low pressure switch 8 is off, that is, when the outside temperature is 0° C. or lower, the variable capacitor 2 is set to the minimum capacity, so that the refrigerant pressure at the outlet of the variable capacitor 2 is reduced until the low pressure switch 8 is turned off. The pressure becomes higher than the predetermined value P1, and the variable capacity compressor 1 continues to operate. At this time, the 5TEP
For the delay processing time 3, the refrigerant pressure shown in FIG. 6 is a predetermined value P.
It must be longer than the time (T2-Tz) for which the value is 1 or more.

Note that the low pressure switch 8 used in this embodiment can also be used as a pressure sensor to achieve the same function.

According to this embodiment, the variable capacity compressor 1 can be operated for a long time even in a low outside temperature range of 0° C. or lower, and failures such as seizure of the variable capacity compressor 1 due to refrigerant leakage can be prevented.

Next, another embodiment of the present invention will be described with reference to FIGS. 7 to 9. FIG. 7 differs from FIG. 1 only in that the low pressure switch is eliminated and a pressure sensor is provided, that the refrigerant flow control valve 7 is an electric on-off valve, and that electrical wiring 22g and 22h are provided.

The function of the present invention is shown in FIG. The series of operations shown in FIG. 8 is performed by the AD converter 10 as described in the first embodiment. C
PUl1. Drive circuit 12. This is carried out by the controller 9 which has a built-in memory 13.

First, when you turn on the air conditioner switch 14, 5TEPI
As shown in , the detected value of the pressure sensor 23 is 206KPa.
(2.1 kg/ff1G) or more, the magnetic clutch 6 is turned on and the variable capacity compressor 1 is operated, and if it is less than 206 KPa (2.1 kg/, ff1G), the process shifts to 5TEP2.

In 5TEP2, for example, when the variable capacitor 2 shown in FIG. 2 is used, the refrigerant flow rate control valve 7 is closed and the process moves to 5TEP4, in which the variable capacitor 2 is set to the minimum capacity.

5TEP4 performs delay processing as in the first embodiment,
5Move to TEP5. Here, it is desirable to determine the delay processing time as described in the first embodiment.

At 5TEP5, the detected value of the pressure sensor 23 is set to 206 again.
It is determined whether the pressure is above KPa (2.1 kg/aIIG), and if it is above 206 KPa, it goes into a monitoring state, and if it is below 206 KPa, the magnetic clutch 6 is turned off and the variable capacity compressor 1 is stopped. FIG. 9 shows changes in the refrigerant pressure at the outlet of the variable capacitor 2 in this example.

In FIG. 9, pressure P2 is variable displacement compressor 1
is the minimum pressure required to move from the minimum capacity to the maximum capacity.

As the outside air temperature decreases, the condenser outlet pressure decreases proportionally. When the temperature reaches 0° C., the refrigerant flow rate control valve 7 closes and the variable capacity condenser 2 becomes the minimum capacity, and the condenser outlet refrigerant pressure increases to a certain value and then begins to decrease. Here, if the refrigerant flow control valve 7 of the variable capacity condenser 2 is not closed, the pressure will decrease as shown by the dotted line in the figure, eventually becoming below P2, the variable capacity compressor will reach the minimum capacity, and the condenser outlet When the pressure becomes less than 206 KPa, the magnetic clutch 6 that transmits power to the variable displacement compressor 1 is turned off as shown in FIG.

According to the present invention, the variable capacity compressor 1 can
In addition, the set pressure at which the low pressure switch 8 is turned off can be set to 2.1 kg/cdG as before.

〔Effect of the invention〕

According to the present invention, there are the following effects.

1. The variable capacity compressor can be used at low outside temperatures, such as below 0°C, and the refrigerant pressure is constantly monitored, so the variable capacity compressor 1 will not cause failures such as seizure due to refrigerant leaks, etc. Never.

2. By using a variable capacity capacitor, the refrigerant pressure discharged from the variable capacity compressor necessary for capacity control of the variable capacity compressor can be obtained even at low outside temperatures.

3. The setting pressure of the low pressure switch is 20 as before.
Even at 6KPa (2.1kg/cJG), the variable capacity compressor can be operated at temperatures below 0°C.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. FIG. 3 is a partial configuration diagram, FIG. 4 is a partial functional explanatory diagram, FIG. 5 is an explanatory diagram of FIG. 1, FIG. 6 is an explanatory diagram of FIG. 5, and FIG. 7 is a configuration diagram of another embodiment. , FIG. 8 is an explanatory diagram of FIG. 7, and FIG. 9 is an explanatory diagram of FIG. DESCRIPTION OF SYMBOLS 1... Variable capacity compressor, 2... Variable capacity capacitor, 6... Magnetic clutch, 7... Refrigerant flow control valve, 8... Low pressure switch, 9... Controller, 23... Pressure sensor.

Claims (6)

[Claims] 1. Equipped with a variable capacity compressor and a variable capacity condenser whose capacity can be changed using a refrigerant flow control valve.
In an automotive air conditioner provided with means for detecting refrigerant pressure and stopping the variable capacity compressor, the variable capacity compressor is operated with priority over the variable capacity compressor stopping means when the automobile air conditioner is started. An air conditioner for an automobile, characterized in that a means is provided. 2. A refrigerant pressure sensor, a refrigerant temperature sensor, or both sensors are provided on the refrigerant outlet side of the variable capacity condenser, and the variable capacity compressor 2. The air conditioner for an automobile according to claim 1, further comprising means for operating the air conditioner. 3. 3. The air conditioner for an automobile according to claim 1, further comprising means for limiting the functional time of said variable capacity compressor operating means to a first predetermined value. 4. Means is provided for opening and closing the refrigerant flow control valve of the variable capacitor based on the detected value of a refrigerant pressure sensor or a refrigerant temperature sensor or both of the sensors provided on the refrigerant outlet side of the variable capacitor, or the temperature of the evaporator. 4. An air conditioner for an automobile according to claim 1 or 3, characterized in that: 5. Claim 2 or 3, wherein the variable capacity compressor is operated when a detected value of a refrigerant pressure sensor or a refrigerant temperature sensor provided on the outlet side of the variable capacity condenser is a second predetermined value or more. The method for controlling an air conditioner for an automobile according to item 3. 6. Claim 1, wherein the refrigerant flow control valve of the variable capacitor is closed when the detected value of the refrigerant pressure sensor or the refrigerant temperature sensor or the value corresponding to the temperature of the evaporator is equal to or lower than a fourth predetermined value. A method for controlling an air conditioner for an automobile according to item 5.