JPH10185372A - Shortage-of-refrigerant detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the correct detection of shortage of refrigerant by one set of temperature sensor by a method wherein it is decided that the refrigerant is short when the temperature of air, which is detected by an air temperature detecting means immediately after passing through an evaporator, is higher than a predetermined temperature, determined based on an evaporating pressure, when the evaporating pressure of the evaporator is controlled in constant. SOLUTION: Upon the operation of an air conditioner for motorcar, an air- conditioning control device 50 decides at first whether an air-conditioning switch 56a is turned on or not and when it is YES, an objective outlet temperature of air into a cabin is operated to control an inside and outside air mode, an air outlet mode, a blower voltage and the opening degree of an air mix door. When the inside and outside air mode is outside air introducing mode, an evaporating pressure regulating valve is decided whether the same valve is controlling the evaporating pressure in an evaporator in constant actually under the set air-conditioning condition or not. When it is decided YES, the detecting temperature of an air temperature sensor 55, detecting the temperature of air after passing through the evaporator, is decided whether it is higher than 5 deg.C, for example, or not whereby the shortage of refrigerant is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle shortage detecting device for a refrigeration cycle, and more particularly to a refrigeration cycle provided with an evaporation pressure regulating valve and an internal variable displacement compressor.

[0002]

2. Description of the Related Art Conventionally, for example, in a refrigeration cycle apparatus having a variable capacity compressor, there is a method described in Japanese Patent Application Laid-Open No. 4-123926 for detecting a shortage of refrigerant at the time of variable capacity. Conventional device). The refrigeration cycle in this conventional apparatus has an external variable displacement compressor that varies the discharge capacity in accordance with the cooling load by controlling the suction refrigerant pressure and the amount of current supplied to the electromagnetic coil. In this conventional apparatus, when the compressor has a variable capacity (the cooling load is not so large,
o, when the outside air temperature is lower than a predetermined value), an air temperature sensor for detecting the air temperature immediately after passing through the evaporator is provided downstream of the evaporator (hereinafter, evaporator) in order to detect the shortage of the refrigerant. In addition, a refrigerant temperature sensor is provided in a refrigerant pipe between the expansion valve and the evaporator.

Specifically, when the temperature difference between the air temperature detected by the air temperature sensor and the refrigerant temperature detected by the refrigerant temperature sensor is larger than a predetermined value ΔT, it is considered that the degree of heating by the evaporator is large. It is determined that the refrigerant is insufficient.

[0004]

However, in the above-mentioned conventional apparatus, two temperature sensors such as an air temperature sensor and a refrigerant temperature sensor are required as described above in order to detect a shortage of the refrigerant, and the number of parts is increased. Is complicated. Therefore, an object of the present invention is to detect a shortage of refrigerant with a single temperature sensor.

[0005]

By the way, in the refrigerating cycle, in addition to the above-described one having the external variable capacity compressor, in order to prevent the frost of the evaporator, the evaporation pressure in the evaporator is adjusted to be constant. A refrigerant discharge capacity is variable with a control pressure determined based on the high pressure and low pressure (evaporator evaporation pressure) of the refrigeration cycle, which is equipped with a regulating valve or generally called an internal variable displacement compressor. What controls is well known.

In a refrigeration cycle having such an evaporation pressure regulating valve or a refrigeration cycle having an internal variable capacity, a single temperature sensor can detect a shortage of refrigerant. In other words, the present inventor has found that in a refrigeration cycle including an evaporation pressure adjusting valve, in a control region where the evaporation pressure adjusting valve controls the evaporation pressure in the evaporator to be constant, the temperature of the air passing through the evaporator according to the evaporation pressure is reduced. It was noted that the temperature was almost constant.

Also, in a refrigeration cycle having an internal variable displacement compressor, at the time of variable control for varying the refrigerant discharge displacement of the compressor (when the displacement is reduced), the refrigerant passes through the evaporator according to the control pressure. Attention was paid to the fact that the temperature of the air reached a substantially constant predetermined temperature. Therefore, in the present invention, in the refrigeration cycle having the evaporation pressure control valve and the refrigeration cycle having the internal variable displacement compressor, the air temperature immediately after passing through the evaporator is the evaporation pressure and the evaporation pressure adjusted by the evaporation pressure control valve, respectively. It is determined by the control pressure of the compressor, and if it is higher than this air temperature, it can be determined that the refrigerant is insufficient.

Therefore, in the first aspect of the present invention, a compressor (9) for compressing and discharging a refrigerant, a condenser (10) for condensing the refrigerant discharged by the compressor (9), and a condenser (10) for condensing the refrigerant discharged from the compressor (9). A decompression device (1) for decompressing the refrigerant condensed in (10)
2), an evaporator (7) for evaporating and evaporating the refrigerant decompressed by the decompression device (12), and an evaporation pressure regulating valve (40) capable of controlling the evaporation pressure in the evaporator (7) to be constant. A refrigerant shortage detecting device of the refrigeration cycle device (14), comprising: an air temperature detecting means (55) for detecting an air temperature immediately after passing through the evaporator (7); If the air temperature detected by the air temperature detecting means (55) is higher than a predetermined temperature determined based on the evaporating pressure when the evaporating pressure of the evaporator (7) is controlled to be constant at Is generated.

This eliminates the need for two temperature sensors, such as an air temperature sensor and a refrigerant temperature sensor, as in the prior art, and makes it possible to detect shortage of the refrigerant only with the air temperature sensor (air temperature detecting means), thereby reducing the number of parts. . Also,
In particular, in the invention according to claim 3, the evaporator (7) is a heat exchanger (7) for cooling a vehicle air conditioner, and the evaporator (7).
And a blower (5) for sending the cooled air passing through the evaporator (7) to the cabin of the vehicle, and the air temperature before passing through the evaporator (7). And a blower (5) based on at least the air temperature detected by the pre-evaporator temperature detector (51, 52). Control means (50) for controlling the temperature of the blower, the amount of air blown by the blower (6) by the blow control means (50), and the air temperature detected by the pre-evaporator temperature detecting means (55). A determination means (S50) for determining whether or not the evaporator (7) is in a refrigerant shortage detectable area in which the evaporating pressure of the evaporator (7) is controlled to be constant by a pressure regulating valve;
0), when it is determined that the region is the refrigerant shortage detectable region, a signal indicating that the refrigerant is insufficient is generated.

Thus, the air temperature immediately after passing through the evaporator fluctuates in accordance with the amount of air blown by the blower and the air temperature before passing through the evaporator. Based on the air temperature before passing, it is determined whether or not the refrigerant is in the refrigerant shortage detectable area. When it is determined that the refrigerant is in the refrigerant shortage detectable area, the refrigerant shortage is detected. As a result, the refrigerant shortage can be accurately detected. Further, the blower control means and the evaporator pre-temperature detection means are provided in what is generally called an auto air conditioner, and the number of parts is increased by using an existing air conditioner. Without this, it is possible to reliably detect the shortage of the refrigerant.

Further, in the invention according to claim 4, there is provided a rotational speed detecting means (61) capable of detecting the rotational speed of the compressor (9), and the refrigerant shortage detectable region further includes a rotational speed detecting means (61). ) Is determined by the number of rotations detected. As a result, the refrigerant shortage detectable region is determined in consideration of the rotational speed of the compressor as well.
Insufficient refrigerant can be reliably detected according to the amount of refrigerant sent to the evaporator.

According to the fifth aspect of the present invention, the compressor (9a) for compressing and discharging the refrigerant and the compressor (9a)
A condenser (10) for condensing the refrigerant discharged from the condenser, and a decompression device (1) for decompressing the refrigerant condensed in the condenser (10).
2) and an evaporator (7) for evaporating and evaporating the refrigerant depressurized by the decompression device (12).
a) is an internal variable displacement in which the refrigerant discharge displacement is variably controlled by a control pressure (Pc) determined according to the evaporation pressure (Ps) of the evaporator (7) and the high pressure (Pd) of the refrigeration cycle device (14). An air temperature detecting means (55) for detecting an air temperature immediately after passing through the evaporator (7), wherein the air temperature detected by the air temperature detecting means (55) is a control pressure (Pc). When the temperature is higher than the predetermined temperature determined by the above, a signal indicating that the refrigerant is insufficient is generated.

Thus, the same effect as the first aspect of the invention can be obtained. In particular, the invention of claim 7 has the same effect as the invention of claim 3 in the invention of claim 5. According to the eighth aspect of the invention, the fifth aspect of the invention has the same effect as that of the fourth aspect of the invention.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Next, a first embodiment in which the present invention is used as an air conditioner for a vehicle will be described with reference to FIGS. In the present embodiment, each air-conditioning unit in an air-conditioning unit for air-conditioning a vehicle interior space is configured to be controlled by an air-conditioning control device.

First, the configuration of the air conditioning unit will be described with reference to FIG. The air-conditioning case 1 forms an air flow path toward the vehicle interior. At the air upstream side of the air-conditioning case 1, an inside air inlet 2 for sucking the air inside the vehicle compartment and an outside air inlet 3 for sucking the outside air are formed. An inside / outside air switching door 4 for selectively opening and closing the inside air intake port 2 and the outside air intake port 3 is provided.

As a result, the air conditioner operates as a well-known inside / outside air mode in which the inside air intake port 2 is opened and the outside air intake port 3 is closed, and the inside air intake port 2 is closed and the outside air intake port 3 is opened. And the outside air introduction mode to be switched. The inside / outside air switching door 4 is provided with a driving means 5.
7 (specifically, a servomotor, see FIG. 3).

At the downstream side of the inside / outside air switching door 4,
A blower 5 for generating an airflow toward the vehicle interior is provided. The blower 5 has a blower motor 6 as a driving means.
Driven by The blower 5 blows air toward an evaporator 7 described later. That is, the amount of air blown into the cabin is controlled by the blower voltage applied to the blower motor 6. The blower voltage is determined by the air-conditioning control device 50 (see FIG. 2).

Downstream of the blower 5, an evaporator 7 as a cooling heat exchanger is provided. The evaporator 7 is a component of a well-known refrigeration cycle device 14.
The refrigeration cycle 14 is a compressor 9 (fixed displacement type in this embodiment) that compresses and discharges a refrigerant to a high temperature and a high pressure.
And a condenser 10 for condensing the refrigerant discharged from the compressor 9
And a receiver 11 that stores the refrigerant condensed in the condenser 10 and separates the liquid-phase refrigerant and the gas-phase refrigerant.
And a pressure reducing device 12 (in this embodiment, a temperature-operated expansion valve) for reducing the pressure of the liquid refrigerant from the receiver 11 is introduced,
It has the evaporator 7 for evaporating the liquid refrigerant and a refrigerant pipe 13 connecting them.

In the refrigeration cycle apparatus 14 according to the present embodiment, an evaporating pressure adjusting valve 40 for adjusting the evaporating pressure in the evaporator 7 is provided between the evaporator 7 and the compressor 9 as shown in FIG. Have been. The function of the evaporating pressure control valve 40 will be briefly described below since it is well known. For example, when the required cooling capacity of the evaporator 7 is large, the evaporating pressure of the evaporator 7 increases, and the opening of the evaporating pressure regulating valve 40 is fully opened. On the other hand, when the required cooling capacity of the evaporator 7 is small, the evaporating pressure of the evaporator 7 becomes small,
The valve opening of the evaporating pressure regulating valve 40 is also reduced, and the evaporating pressure of the evaporator 7 is set to a constant value (1.85 kg / c in the present embodiment).
m ² G). In addition, 15 is an outdoor fan.

The compressor 9 is driven by an engine 8 of an automobile. An electromagnetic clutch 16 is connected to the compressor 2. The electromagnetic clutch 16 is controlled to be energized by an air-conditioning control device 50 (see FIG. 3). When the energization is controlled by the air-conditioning control device 50, the electromagnetic clutch 16 transmits the power of the engine 8 to the compressor 9 and When the air conditioner 9 is operated and the air-conditioning control device 50 is de-energized, the transmission of the power of the engine 8 to the compressor 9 is interrupted to stop the compressor 9.

Further, a heater core 17 as a heat exchanger for heating is disposed downstream of the evaporator 7 in the air. The cooling water of the engine 8 flows inside the heater core 17,
The cooling water is used as a heat source to heat the air passing through the heater core 17. On the upstream side of the air from the heater core 17, the ratio of the cool air from the evaporator 7 that passes through the heater core 17 and the bypass passage 1 that bypasses the heater core 17 are provided.
An air mix door 19 is provided for adjusting the rate of passage through the door. The air mix door 19 is driven by its driving means 58 (specifically, a servomotor, see FIG. 2).

Further, at the most downstream side of the air conditioning case 1,
A face outlet 20 for blowing air to the upper body of the passenger in the passenger compartment, a foot outlet 21 for discharging air to the feet of the passenger in the passenger compartment, and a defroster outlet for blowing air toward the inner surface of the windshield 23. 22 are formed. The upstream side of each of the outlets 20 to 22 has a face mode in which conditioned air is blown out from the face outlet 20, a foot mode in which conditioned air is blown out from the foot outlet 21, and conditioned air in the face outlet 20 and the foot blower. Air outlet mode switching doors 24 and 25 for switching between a bi-level mode blowing out from the outlet 21 and a defroster mode blowing out conditioned air from the defroster outlet 22.
Are arranged. In addition, these doors 24 and 25
It is driven by respective driving means 59 and 60 (specifically, each is a servomotor, see FIG. 2).

Next, the configuration of the control system of this embodiment will be described with reference to FIG. The air-conditioning control device 50 includes, as means for detecting an air-conditioning environment factor that affects a vehicle interior, which is an air-conditioned space, an internal air temperature sensor 51 that detects an air temperature in the vehicle interior,
An outside air temperature sensor 52 for detecting the outside air temperature, a solar irradiation sensor 53 for detecting the amount of solar radiation radiated into the vehicle interior, and a heater core 17
Temperature sensor 5 for detecting the temperature of the engine cooling water flowing into the engine
4. A post-evaporator air temperature sensor 55 that detects the degree of air cooling of the evaporator 7 (specifically, the air temperature immediately after passing through the evaporator 7), and is disposed at a position with good operability in the passenger compartment. A signal from each switch on the control panel 56 (for example, a temperature setting device that sets a target temperature in the vehicle compartment) is input. In addition, the control unit 11 has a display unit 4 that is turned on when the refrigerant in the refrigeration cycle device 14 described below is insufficient.
1, and the rotation speed of the vehicle engine (the rotation speed of the compressor 7)
Is connected.

The control panel 56 includes:
An air conditioner switch 56a for automatically starting and controlling the air conditioner based on the air conditioning environment factor and a stop switch (not shown) for stopping the air conditioner are provided. That is, when the air-conditioning switch 56a is turned on, the air-conditioning control controller 50 automatically controls the inside / outside air mode, the blowing mode, and the operating position (opening) of the air mix 19. .

The inside of the air-conditioning control device 50 includes a CP (not shown).
A well-known microcomputer including a U, a ROM, a RAM, and the like is provided. The signals from the sensors 51 to 55 and the control panel 56 are A / D converted by an input circuit (not shown) in the air conditioning control device 50. It is configured to be input to the microcomputer.

When the ignition switch (not shown) of the engine 8 is turned on, the air-conditioning control device 50 is supplied with power from a battery (not shown). Next, an overall control process performed by the microcomputer of the air conditioning control device 50 will be described with reference to FIG. First, in step S10, it is determined whether or not the air conditioning switch 56a is turned on (ON). Here, in the present embodiment, since the evaporating pressure adjusting valve 40 is provided, the compressor 9 is always operated (turned on) when the air conditioning switch 56a is turned on. Therefore, in step S10, it is determined whether the compressor 9 is operating.

If it is determined that the compressor 9 is operating, the flow advances to step S20 to read and store the air conditioning environment factors as various information. And
In the next step S30, the air-conditioning control state is set based on the air-conditioning environmental factors read in step S20. Briefly, a target outlet temperature (TAO) into the vehicle compartment is calculated from the information read in step S20, and the inside / outside air mode, the outlet mode, the blower voltage, and the target outlet temperature TAO are calculated based on the target outlet temperature TAO. The opening of the air mix door 19 is controlled.

In step S40, it is determined whether the inside / outside air mode set in step S30 is the outside air introduction mode. That is, outside air passes through the evaporator 7 in the outside air introduction mode, and inside air passes through the evaporator 7 in the inside air circulation mode. Therefore, in this step S40, it is determined whether the air before passing through the evaporator 7 is inside air or outside air. If the mode is the outside air introduction mode, the process proceeds to step S50. If the mode is the inside air circulation mode, the process proceeds to step S60.

Subsequently, in step S51, it is determined whether or not the evaporating pressure regulating valve 40 really controls the evaporating pressure in the evaporator 7 to be constant in the air conditioning control state set in the above-mentioned step S30. Do. Here, FIG. 4 shows the outside air temperature detected by the outside air temperature sensor 52 and the engine rotation speed detected by the rotation speed sensor 61 (same as the rotation speed of the compressor 9).
5 shows a map that determines whether or not the refrigerant of the refrigeration cycle device 14 is in a detectable region based on the blower voltage (the amount of air blown to the evaporator 7).

That is, in the present embodiment, it is determined from the map shown in FIG. 4 whether or not the refrigerant pressure detection valve 40 is in the refrigerant shortage detectable area in a state where the evaporation pressure is controlled to a constant value. Then, as shown in FIG. 4C, when the blower voltage is Hi, the air volume passing through the evaporator 7 increases, the outside air temperature increases, and the evaporator 7 increases as the rotation speed of the compressor increases. Cooling capacity (amount of refrigerant sent to evaporator 7)
Becomes larger, and if the region is indicated by arrow C1 in the figure, the evaporator 7
Even if it is cooled by the above, since the air temperature immediately after passing through the evaporator 7 fluctuates and becomes higher than 0 to 1 ° C., it cannot be determined that the refrigerant is short. That is, in the region indicated by the arrow C2, the air temperature immediately after passing through the evaporator 7 is 0 to 1 ° C.,
Refrigerant shortage can be detected.

As shown in FIG. 4B, when the blower voltage is Mid, the air volume passing through the evaporator 7 is medium, the outside air temperature is higher, and the evaporator 7 The cooling capacity (amount of refrigerant sent to the evaporator 7) becomes large, and in the region indicated by the arrow B1 in the figure, even if the air is cooled by the evaporator 7, the air temperature immediately after passing through the evaporator 7 fluctuates. However, since the temperature is higher than 0 to 1 ° C., it cannot be determined that the refrigerant is insufficient. That is, the area indicated by the arrow B2 is the evaporator 7
The air temperature immediately after passing through is 0 to 1 ° C., which is a refrigerant shortage detectable area.

Further, as shown in FIG. 4 (a), when the blower voltage is Lo, the amount of air passing through the evaporator 7 is small, the outside air temperature increases, and the evaporator 7 increases as the rotational speed of the compressor increases. Has a large cooling capacity (amount of refrigerant sent to the evaporator 7), and in the region indicated by the arrow B1 in the figure, even if the air is cooled by the evaporator 7, the air temperature immediately after passing through the evaporator 7 fluctuates. , 0 to 1 ° C., the refrigerant shortage cannot be determined. That is, the area indicated by the arrow A2 has an air temperature of 0 to 1 ° C. immediately after passing through the evaporator 7, and is a refrigerant shortage detectable area.

Then, the determination result at step S50 is Y
If it is ES, that is, the area indicated by A2, B2, and C2 in FIG. 4, the process proceeds to step S70. In step S70,
The detected temperature of the air temperature sensor 55 after the evaporator is 0 to 1 ° C.
By determining whether the temperature is higher than a higher set temperature (5 ° C. in the present embodiment), it is possible to determine whether the refrigerant is insufficient.

Here, in the present embodiment, the set temperature of 5 ° C. is a value determined based on experimental data as shown in FIG. If the blower voltage (air volume) is Lo and the outside air temperature is 20 ° C., and the amount of refrigerant charged in the refrigeration cycle device 14 is 100%, the amount of refrigerant decreases to about 20%. It is the temperature when you are.

Further, as shown in FIG. 5, the value of the set temperature of 5 ° C. changes depending on the amount of the refrigerant, and can be set arbitrarily. In addition, as for the value of the set temperature of 5 ° C., the predetermined value increases as the outside air temperature increases, as can be seen from the diagram, even if the same refrigerant is reduced (about 20%). If the amount of refrigerant charged in the refrigeration cycle device 14 is an appropriate amount, the detected temperature of the post-evaporator air temperature sensor 55 is 0 to 1 ° C., and if the determination result in step S70 is YES,
Proceeding to step S80, a signal indicating that the refrigerant is insufficient is generated. Then, the process proceeds to step S90, where the display unit 4
Turn on 1 to let the occupant visually recognize that the refrigerant is insufficient.

If the result of the determination in step S70 is NO
In the case of, the process proceeds to step S100, and it is determined that the refrigerant is normal without a shortage of the refrigerant, and the process exits the flowchart. On the other hand, if the decision result in the step S40 is NO, that is, if it is the inside air circulation mode, the process proceeds to a step S51, and since the air passing through the evaporator 7 is the inside air, the refrigerant in the steps S51 to S101 based on the inside temperature. Determine shortage. Note that this step S51 is the same as that shown in FIG.
The horizontal axis is the internal temperature. Also, the internal temperature uses, of course, the detection value of the internal temperature sensor.

Steps S71, 91 and 101 are as follows:
Each is the same as the above steps S70, 90, 100,
In step S80, the outside air temperature in FIG. 5 is set as the inside air temperature, and a description thereof will be omitted. Thus, in the present embodiment, it is possible to detect the shortage of the refrigerant similarly in the inside air circulation mode and the outside air introduction mode. And
In the present embodiment, the existing various sensors of the automatic air conditioner in which the air conditioner is automatically controlled can be used to detect the shortage of the refrigerant only by the detection value of the post-evaporator temperature sensor 55.
The number of parts can be reduced and the system for detecting a shortage of refrigerant can be simplified.

In this embodiment, as described above, the air temperature immediately after passing through the evaporator varies depending on the blower voltage, the rotation speed of the compressor 9, and the air temperature before passing through the evaporator 7. Therefore, based on the blower voltage, the rotation speed of the compressor 9 and the air temperature before passing through the evaporator, it is determined whether or not the refrigerant is in the refrigerant deficiency detectable area. Detects refrigerant shortage. As a result, the refrigerant shortage can be accurately detected.

(Second Embodiment) Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in the configuration of the refrigeration cycle device 14, and does not have the evaporation pressure regulating valve 40 as shown in FIG. It has a variable capacity mechanism (hereinafter, referred to as a compressor 9a).

Next, the internal structure of the compressor 9 will be briefly described with reference to FIG. The internal variable displacement mechanism described below is disclosed in Japanese Patent Application Laid-Open No. 4-301189, and a detailed description thereof will be omitted. Housing 31 of compressor 9
A rotating shaft 32 that rotates with the rotation of the engine 8
Are provided, and a swash plate 33 is provided so as not to rotate together with the rotating shaft 32. And
When the cylinder case 34 rotates together with the rotating shaft 32, a sliding member 36 provided at one end of the piston 35
Slides along the surface of the swash plate 33, whereby the piston 35 reciprocates in the cylinder chamber 37 in the left-right direction in the figure. That is, the stroke of the piston 35, that is, the discharge capacity of the compressor 9 changes according to the inclination of the swash plate 33.

The swash plate 33 has a part positioned at a holder 38.
And the piston 39. Due to the elastic force of the coil spring 40, a force that pushes the above part of the swash plate 33 rightward in the drawing acts on the holder 38, and the control pressure Pc in the control pressure chamber 41 acts on the piston 39.
As a result, a force is exerted to push the above-mentioned part of the swash plate 33 leftward in the figure. That is, the inclination of the swash plate 33 is determined by the elastic force and the control pressure Pc.

In the control pressure chamber 41, a low pressure Ps on the side of the evaporator 7 is led through the communication passages 42 and 43, and the high pressure Pd, which is compressed by the compressor 9 itself and becomes high. Is guided through the communication passages 42 and 44. Further, a valve body 45 is provided in a communication portion between the communication passages 42 and 43, and the position of the valve body 45 changes to change the passage area in the communication portion, so that the control pressure Pc changes. It is configured to be.

Here, when the cooling load is large, the low pressure Ps increases, so that the diaphragm 46 is pushed downward in the figure. Then, through the rod 47, the valve body 4
5, the control pressure Pc in the control pressure chamber 41 increases. When the control pressure Pc increases, the force of the piston 39 pressing the above-described part of the swash plate 33 to the left in the drawing increases, and as a result, the inclination of the swash plate 33 increases, and the discharge capacity of the compressor 2 decreases. growing.

On the other hand, when the cooling load is small, the low pressure Ps becomes low, so that the diaphragm 46 is pushed upward in the figure. Then, the valve body 45 rises upward in the drawing via the rod 47, so that the control pressure P in the control pressure chamber 41 is increased.
c becomes lower. Therefore, as a result, the inclination of the swash plate 33 becomes small, and the discharge capacity of the compressor 9 becomes small. As described above, the compressor 9 of the present embodiment is a so-called internal variable displacement compressor in which the discharge capacity is automatically changed according to the cooling load, and such an internal variable displacement compressor is used. Thus, the air temperature after passing through the evaporator 7 is controlled to be substantially constant at a predetermined temperature (for example, 0 ° C. to 1 ° C.).

Accordingly, the shortage of the refrigerant can be detected in the same manner as in the flowchart of FIG. 3 described above, and the description is omitted here. Note that such a compressor 9a is always operating (ON) when the air conditioning switch 56a is ON. And, in the second embodiment, the same effects as in the first embodiment can be obtained. (Other Embodiments) In the above embodiment, the auto air conditioner for automatically controlling the inside / outside air mode, the blower voltage, the air mix door, and the like has been described. However, based on the concept described in the first and second embodiments, The present invention is also applicable to a manual air conditioner in which the inside / outside air mode, blower voltage, and the like can be changed only by manual operation.

Further, in each of the above embodiments, the map shown in FIG. 4 is created in consideration of the number of revolutions of the compressors 9 and 9a. Further, in each of the above embodiments, the air conditioner for an automobile has been described, but the present invention is not limited to this, and can be applied to an air conditioner for home or business use.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner and a refrigeration cycle device 14 according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a control device 50 in the first embodiment.

FIG. 3 is a flowchart in the first embodiment and the second embodiment.

FIG. 4 is a diagram showing a refrigerant shortage determination possible region according to the first and second embodiments of the present invention.

FIG. 5 is a diagram showing a correlation between the amount of charged refrigerant and the temperature of the air passing through the evaporator 7 in the first and second embodiments of the present invention.

FIG. 6 is a schematic sectional view of an internal variable displacement compressor 9a in the second embodiment.

[Explanation of symbols]

9, 9a: compressor, 10: condenser, 12: decompression device 14: refrigeration cycle device, 40: evaporation pressure regulating valve, 50
... Control unit 55 ... Evaporator air temperature sensor

Claims (8)

[Claims] A compressor for compressing and discharging a refrigerant.
A condenser (10) for condensing the refrigerant discharged from the compressor (9); a decompression device (12) for decompressing the refrigerant condensed in the condenser (10); and a decompression device (12) A refrigerating cycle device (14) comprising: an evaporator (7) for evaporating and evaporating the refrigerant decompressed in the evaporator;
Refrigerant shortage detecting device, comprising air temperature detecting means (55) for detecting the air temperature immediately after passing through the evaporator (7), and the evaporator (40) When the air pressure detected by the air temperature detecting means (55) is higher than a predetermined temperature determined based on the evaporation pressure when the evaporation pressure in (7) is controlled to be constant, the refrigerant runs short. A shortage detection device for a refrigerant, which generates a signal indicating that the refrigerant is present. 2. A refrigerant shortage occurs when the air temperature detected by the air temperature detection means (55) is higher than a predetermined temperature set by a predetermined value higher than a predetermined temperature determined based on the evaporation pressure. The refrigerant shortage detection device according to claim 1, wherein a signal for determining that the refrigerant is present is generated. 3. The evaporator (7) is a heat exchanger (7) for cooling an air conditioner of a vehicle, and blows air toward the evaporator (7). A blower (5) for sending the cooled air that has passed through into the cabin of the vehicle, and a pre-evaporator temperature detecting means (51, 52) for detecting an air temperature before passing through the evaporator (7) And the blower (5) based on at least the air temperature detected by the pre-evaporator temperature detection means (51, 52).
Control means (50) for automatically controlling the amount of air blown by the air blower, the amount of air blown by the blower (6) by the air blow control means (50), and the temperature detection means (51, 52) detected before the evaporator. Determining means (S50) for determining whether or not the evaporation pressure of the evaporator (7) is in a refrigerant shortage detectable area in which the evaporation pressure of the evaporator (7) is controlled to be constant by the evaporation pressure adjusting valve based on the determined air temperature. The method according to claim 1, wherein the determination unit (S <b> 50) generates a signal indicating that the refrigerant is insufficient when it is determined that the region is the refrigerant shortage detectable region. Refrigerant shortage detection device. 4. A rotation speed detecting means (61) capable of detecting a rotation speed of the compressor (9), wherein the refrigerant shortage detectable area is further detected by the rotation speed detecting means (61). The refrigerant shortage detection device according to claim 3, wherein the rotation speed is determined. 5. A compressor (9a) for compressing and discharging a refrigerant.
A condenser (10) for condensing the refrigerant discharged from the compressor (9a); a decompression device (12) for decompressing the refrigerant condensed in the condenser (10); and a decompression device (1).
Evaporator (7) for evaporating and evaporating the refrigerant decompressed in 2)
A refrigerant shortage detection device for a refrigeration cycle device (14), comprising: a compressor (9a) configured to control an evaporation pressure (Ps) of the evaporator (7) and a high pressure ( By the control pressure (Pc) determined according to Pd),
An air temperature detecting means (55) for detecting an air temperature immediately after passing through the evaporator (7); and an air temperature detecting means (55). ) Detects the air temperature,
A refrigerant shortage detection device that generates a signal indicating that refrigerant is insufficient when the temperature is higher than a predetermined temperature determined by the control pressure (Pc). 6. When the air temperature detected by said air temperature detecting means (55) is higher than a predetermined temperature set by a predetermined value higher than a predetermined temperature determined based on said control pressure (Pc), refrigerant is discharged. The refrigerant shortage detecting device according to claim 5, wherein a signal for determining that the refrigerant is insufficient is generated. 7. The evaporator (7) is a cooling heat exchanger (7c) for a vehicle air conditioner, and blows air toward the evaporator (7). A blower (5) for sending the cooled air that has passed through into the cabin of the vehicle, and a pre-evaporator temperature detecting means (51, 52) for detecting an air temperature before passing through the evaporator (7) A blower control means (50) for automatically controlling a blower volume of the blower based on at least the air temperature detected by the evaporator (7) front temperature detector, and a blower control means (50) Based on the amount of air blown by the blower (5) and the air temperature detected by the pre-evaporator temperature detecting means (51, 52). A determination unit (S50) for determining whether the area is an area 7. The refrigerant shortage detecting device according to claim 5, wherein a signal indicating that the refrigerant is insufficient is generated when the determination unit (S50) determines that the region is the refrigerant shortage detectable region. . 8. A rotational speed detecting means (61) capable of detecting a rotational speed of the compressor, wherein the refrigerant shortage detectable region further includes a rotational speed detected by the rotational speed detecting means (61). The refrigerant shortage detection device according to claim 7, wherein the refrigerant shortage detection device is determined in advance.