JPH04251174A - Air conditioner - Google Patents

Abstract

PURPOSE:To make it possible to decide a locked state of a compressor easily and definitely and detect the leakage of refrigerant as well based on an optical sensor installed on the way of a flow passage where said refrigerant is converted into liquid phase and a pressure sensor which detects the pressure in said flow passage. CONSTITUTION:A refrigerant flow passage 1 comprises a pipeline 2 which forms a refrigerant circulation flow passage, a compressor 3 sequentially installed on the way of the pipeline 2, a condenser 4, and a vaporizer 5. A receiver tank 9 which stored refrigerant temporarily is installed between the condenser 4 and the vaporizer 5. The receiver tank 9 is further provided with a pressure sensor 10 which detects the pressure of the refrigerant. Under the configuration described above, an optical sensor 21 is laid out in the proximity of the receiver tank 9 so as to detect if the refrigerant is in a liquid phase or a gaseous phase. Then, the locked state of the compressor 3 is decided based on each detection signal transmitted from the pressure sensor and the optical sensor 21.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner suitably used as a cooling device for, for example, an automobile.

0002

[Prior Art] Generally, automobiles, houses, etc. have air conditioners,
It is equipped with an air conditioner such as a heating system to supply warm or cool air into the room. Here, an air conditioner as a cooling device for an automobile according to the prior art will be explained based on FIG.

In the figure, reference numeral 1 indicates a refrigerant flow path, and the refrigerant flow path 1 is connected to a pipe 2 forming a circulation flow path in which a refrigerant such as ammonia or fluorocarbon gas circulates, and in the middle of the pipe 2 there is a refrigerant circulation direction (in the figure). , a compressor 3, a condenser 4, and an evaporator 5, which are sequentially provided along the direction of arrow A).
The heat exchange surface faces into the operator's cab (not shown). After being compressed by the compressor 3, the refrigerant passes through the condenser 4 and evaporator 5, where it sequentially undergoes a phase transition from high-pressure gas to high-pressure liquid to low-pressure gas, and in the evaporator 5, the liquid changes to gas. When it transfers, it takes heat from inside the driver's cabin and cools the inside of the driver's cabin.

Reference numeral 6 denotes an automobile engine, and the engine 6 is provided with a pulley 6A for driving the compressor 3. 7 is an electromagnetic clutch that drives and stops the compressor 3, and the electromagnetic clutch 7 is provided with a pulley 7A. 8 indicates a V-belt connecting each pulley 6A, 7A. Here, the electromagnetic clutch 7 is connected and connected by an air conditioner switch (not shown) provided in the driver's cab.
When released (ON, OFF control) and connected (ON), the rotation of the engine 6 is controlled by the pulley 6A, V-belt 8, and pulley 7A.
The signal is transmitted to the compressor 3 via the compressor 3, and the compressor 3 is driven.

A receiver tank 9 is located between the condenser 4 and the evaporator 5 and is provided in the middle of the pipe 2 to temporarily store the refrigerant in a liquid state. A viewing window 9A is provided to visually check the liquefaction status of the refrigerant. Reference numeral 10 denotes a pressure sensor that is provided in the receiver tank 9 and detects the refrigerant pressure. When the refrigerant pressure exceeds a predetermined pressure, the pressure sensor 10 detects this as excessive pressure and sends this detection signal to a control unit (not shown). ). When the refrigerant pressure in the pipe 2 exceeds a predetermined pressure, the pressure sensor 10 outputs an OFF signal to the control unit and disengages the electromagnetic clutch 7, thereby preventing the compressor from bursting in the pipe 2, etc. It is designed to stop 3. Also,
When the refrigerant pressure drops to another predetermined pressure for restart, the pressure sensor 10 detects it and the control unit sends an O
The N signal is output, the electromagnetic clutch 7 is connected again, and the compressor 3 is rotationally driven by the engine 6. Reference numeral 11 denotes an expansion valve located between the receiver tank 9 and the evaporator 5, and provided in the middle of the pipe 2. The expansion valve 11 is constituted by a known refrigerant pressure reducing valve, and the liquefied high-pressure refrigerant is evaporated. The refrigerant is made to flow in the direction of arrow A toward the evaporator 5 while reducing the pressure of the refrigerant to a predetermined pressure so that it is easily vaporized while passing through the evaporator 5.

In the conventional air conditioner configured as described above, when the air conditioner switch is turned on, the compressor 3 is activated, the refrigerant begins to circulate within the pipe 2, and the refrigerant passage 1 is activated. The driver's cabin is air-conditioned. Excess pressure in the refrigerant flow path 1 is controlled by a pressure sensor 10 provided in the receiver tank 9. That is, since the compressor 3 is rotationally driven by the engine 6 via the V-belt 8, etc., when the rotation of the engine 6 increases, the rotation speed of the compressor 3 also increases, and the refrigerant pressure in the pipe 2 increases. . If excessive pressure is generated within the pipe 2, the pipe 2 may burst or the compressor 3 may overheat and be damaged. Therefore, the pressure sensor 10 provided in the receiver tank 9
The refrigerant pressure in the pipe 2 is detected, and when the refrigerant pressure exceeds a predetermined pressure, this is treated as excess pressure and the compressor 3
The electromagnetic clutch 7 of the engine 6 is automatically turned off to cut off transmission of the high-speed rotation of the engine 6 to the compressor 3, and the compressor 3 is stopped.
This is intended to prevent overheating of the pipes 2 and the like, as well as to prevent bursts of the pipes 2 and the like. Further, an expansion valve 11 is located in the middle of the pipe 2 between the receiver tank 9 and the evaporator 5.
is provided, and the expansion valve 11 adjusts its opening according to the refrigerant pressure so that the refrigerant in the liquid phase is completely vaporized while it circulates and passes through the evaporator 5 in the direction of arrow A. It has become.

[0007]

However, in the prior art described above, for example, the compressor 3 sucks liquid refrigerant,
If compressed, this compressor 3 may become locked. In this case, the refrigerant in the piping 2 cannot be circulated, and the operator must check whether the effectiveness of the air conditioner has deteriorated due to the locked state of the compressor 3 or whether the effectiveness of the air conditioner has deteriorated due to refrigerant leakage. It was not possible to determine. Therefore, in the conventional technology,
Countermeasures have been taken, such as installing an external rotation speed detection sensor or the like on the compressor 3 to detect the locked state of the compressor 3.

[0008] However, in existing air conditioners, installing an external rotation speed detection sensor on the compressor 3 requires modification of the compressor 3 because the compressor 3 differs depending on the vehicle model, and the work is complicated. The problem is that it becomes very complex. Further, even if the compressor 3 is provided with a rotation speed detection sensor, there is a problem in that refrigerant leakage cannot be detected.

The present invention has been developed in view of the above-mentioned problems of the prior art.The present invention is capable of distinguishing and detecting refrigerant leakage and the locked state of the compressor, and eliminates the need for a rotation speed detection sensor, etc. The purpose is to provide an air conditioner with improved performance.

0010

[Means for Solving the Problems] A feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is that the refrigerant is located in the middle of the flow path where the refrigerant is to be in a liquid phase, and the condenser and evaporator are connected to each other. an optical sensor that is provided between the refrigerant and detects whether the refrigerant is in a liquid phase or a gas phase; and an optical sensor that detects whether the compressor is in a locked state based on detection signals from the optical sensor and the pressure sensor. The purpose of this invention is to provide a determination means for determining whether the

[0011]

[Operation] With the above configuration, the locked state of the compressor can be reliably detected by the detection signals from the optical sensor and the pressure sensor, and refrigerant leakage can also be detected.

0012

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 6. In the embodiment, the same components as those in the prior art described above are given the same reference numerals, and their explanations will be omitted.

In the figure, 21 is an optical sensor located in the middle of the refrigerant flow path 1 where the refrigerant is to be in a liquid state, and is provided near the receiver tank 9; 22 is the main body casing of this optical sensor 21; This main casing 22 is shown in FIG.
As shown in FIG.
A, and bottomed cylindrical stagnation parts 22B and 22C located in the middle of this refrigerant passage part 22A and protruding in the vertical direction, and both openings of this refrigerant passage 22A are connected to piping 2. .

Reference numeral 23A is a light emitting element of the optical sensor 21, which is disposed on the bottom side of the stagnation part 22B. 23B is a light receiving element of the optical sensor 21, and is arranged on the bottom side of the stagnation part 22C. The light emitting element 23A emits light toward the light receiving element 23B by receiving power from a battery (not shown) as a power source. And the light receiving element 23
In B, since the amount of light transmitted changes depending on whether the refrigerant in the main body casing 22 is in the gas phase or liquid phase, the change in the amount of light transmitted can be extracted as a change in the resistance value (voltage value). It looks like this.

As shown in FIG. 3, 24 is an input/output control circuit 2.
5 shows a control unit composed of a microcomputer including a processing circuit 26, a storage circuit 27, etc., and the control unit 24 is connected to the input/output control circuit 2.
An air conditioner switch 28, a pressure sensor 10, an optical sensor 21, etc. are connected to the input side of 5, and an electromagnetic clutch 7, a compressor warning device 29, a refrigerant leak warning device 30, etc. are connected to the output side, and the compressor warning device 29 and The refrigerant leak warning device 30 includes a lamp, a buzzer, a voice synthesizer, etc. installed in the operator's cab (not shown), and is designed to warn when the compressor 3 is stopped due to locking or when there is a shortage of refrigerant. And control unit 2
4 stores the program shown in FIG. 6 in a storage circuit 27 such as ROM or RAM. Furthermore, in the storage area 27A of the storage circuit 27, the detection voltage VF of the optical sensor 21 is stored.
The set voltage V that determines whether the refrigerant is in the gas phase or liquid phase based on
FO and a set voltage VP that determines whether the compressor 3 is in a locked state based on the detected voltage VP of the pressure sensor 10
O etc. are stored.

Here, FIG. 4 shows the output voltage value (resistance value) characteristics of the light receiving element 23B, which is the detection part of the optical sensor 21. When refrigerant leakage occurs, the characteristics are as shown in FIG. 4(a), and the compressor 3 In the locked state, the characteristics are as shown in FIG. 4(b). Further, FIG. 5 shows the output voltage value characteristics of the pressure sensor 10. When a refrigerant leak occurs, the characteristics are as shown in FIG. 5(a), and when the compressor 3 is in a locked state, the characteristics are as shown in FIG. 5(b). According to each of these characteristic diagrams, the detected voltages VP and VF of the pressure sensor 10 and the optical sensor 21 are different depending on whether there is a refrigerant leak or when the compressor 3 is in the locked state. In particular, when the compressor 3 is in the locked state, the compressor 3 stops, so
As shown in FIG. 4(B) and FIG. 5(B), each sensor 10, 21
The detected voltages VP and VF change suddenly. However, when the refrigerant leaks, the refrigerant gradually leaks even though the compressor 3 continues to operate, so it can be seen that the detected voltage VP of the pressure sensor 10 gradually decreases as shown in FIG. 5(a). The air conditioner of this embodiment is constructed as described above, but its basic operation is not particularly different from that of the prior art.

[0017]The refrigerant leakage and lock state determination alarm processing of the compressor 3 by the control unit 24 will now be described with reference to FIG. First, by closing the air conditioner switch 28, the electromagnetic clutch 7 transmits the rotation of the engine 6 to the compressor 3 to operate the air conditioner. When the processing operation starts, in step 1, the detection from the optical sensor 21 is detected. The voltage VF and the detected voltage VP of the pressure sensor 10 are read, and in step 2, the detected voltage VF is stored in the memory area 27A of the memory circuit 27.
It is determined whether the voltage is higher than the set voltage VFO at the time of the phase transition between the liquid phase and the gas phase of the refrigerant stored in advance. Therefore, the process moves to step 3, and if the determination is "NO", the process returns to step 1, and the air conditioner is operated while the compressor 3 remains driven.

Next, in step 3, the detected voltage VP read in step 1 is stored in the storage area 27A of the storage circuit 27.
It is determined whether the voltage is higher than the preset voltage VPO stored in advance. If the determination is "YES", it can be determined that the compressor 3 is not in the locked state, so the process moves to step 4. If the determination is "NO", the will move on to step 6.

In step 4, the detection voltage VF of the optical sensor 21 is changed to the set voltage VF by the processing in step 2.
Since the detected voltage VP of the pressure sensor 10 has become larger than the set voltage VPO due to the processing in step 3, it can be determined that there is a refrigerant leak, and the refrigerant leak warning device 30 alerts the driver to the refrigerant leak. It is supposed to be done. Then, in step 5, in order to prevent the compressor 3 from seizing, the electromagnetic clutch 7 is used to disconnect the engine 6 and the compressor 3 is stopped.

On the other hand, in step 6, the detected voltage VF of the optical sensor 21 is larger than the set voltage VFO due to the process of step 2, and the detected voltage VP of the pressure sensor 10 is
Since the voltage is smaller than the set voltage VPO, it can be determined that the compressor 3 is in a locked state, and the compressor warning device 29 warns the driver of this. Then, as described above, in step 5, the electromagnetic clutch 7 stops driving the compressor 3.

Thus, according to this embodiment, the optical sensor 21 is provided in the middle of the pipe 2 where the refrigerant should be in the liquid phase, and the refrigerant in the gas phase is detected in the refrigerant that should normally be in the liquid phase. The compressor warning device 29 and The refrigerant leak warning device 30 can be operated appropriately,
It is possible to inform the driver of the cause of poor cooling efficiency. When carrying out repairs, the operator can determine whether the area to be repaired is a failure of the compressor 3 or a refrigerant leak based on this alarm, and the repair work can be carried out quickly.
Workability can be improved. Furthermore, since the compressor 3 can be immediately stopped in the event of an alarm, the life of the compressor 3 can be effectively extended, and the reliability and life of the air conditioner can be extended.

In this embodiment, steps 2 and 3 of the program shown in FIG. 6 are specific examples of determining means for determining whether the compressor 3 is in a locked state. Further, in this embodiment, the light emitting element 23A and the light receiving element 23B of the optical sensor 21 are provided in the stagnation parts 22B and 22C, respectively, but instead of providing them in the stagnation parts 22B and 22C, As in the modified example shown in FIG.

[0023]

As described in detail above, according to the present invention, an optical sensor is provided in the middle of the flow path in which the refrigerant in the refrigerant piping of an air conditioner should be in a liquid phase state, and the pressure in the flow path is controlled. A pressure sensor is provided to detect the compressor, and based on these detection signals, it is determined whether or not the compressor is in the locked state. Therefore, the locked state of the compressor can be detected without detecting the rotation speed of the compressor, etc. It is also possible to detect refrigerant leaks, thereby reliably preventing compressor seizure and the like. Furthermore, at the time of repair, it can be determined whether the failure of the air conditioner is due to a refrigerant leak or a malfunction of the compressor, thereby effectively improving workability during repair of the air conditioner.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a refrigerant flow path of an air conditioner according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of essential parts of the same embodiment.

FIG. 3 is a control block diagram of the same embodiment.

FIG. 4A is a characteristic diagram of the optical sensor when a refrigerant leaks in the same embodiment, and FIG. 4B is a characteristic diagram of the optical sensor when the compressor is locked in the same embodiment.

FIG. 5A is a characteristic diagram of the pressure sensor when a refrigerant leaks in the same embodiment, and FIG. 5B is a characteristic diagram of the pressure sensor when the compressor is locked in the same embodiment.

FIG. 6 is a flowchart showing determination alarm processing in the same embodiment.

FIG. 7 is an enlarged sectional view of a main part of another embodiment of the present invention.

FIG. 8 is an overall view of a refrigerant flow path of a conventional air conditioner.

[Explanation of symbols]

1 Refrigerant flow path 2 Piping 3 Compressor 4 Condenser 5 Evaporator 10 Pressure sensor 21 Optical sensor 24 Control unit 31 Optical sensor

Claims (1)

[Claims] 1. A system comprising: piping through which refrigerant circulates; a compressor, a condenser, and an evaporator that are sequentially provided along the circulation direction of the refrigerant in the middle of the piping; and a pressure sensor that detects the pressure within the piping. In the air conditioner, the air conditioner is provided between the condenser and the evaporator, and is located in the middle of a flow path in which the refrigerant is to be in a liquid phase, so that the refrigerant is in a liquid phase or a gas phase. What is claimed is: 1. An air conditioner comprising: an optical sensor that detects a compressor; and a determining means that determines whether a compressor is in a locked state based on detection signals from the optical sensor and the pressure sensor.