JPH053863U - Air conditioner - Google Patents

Abstract

(57) [Abstract] [Purpose] Whether the refrigerant is in the liquid phase or the gas phase is determined by using the pressure sensor and the temperature sensor, and thus the refrigerant is properly filled or the refrigerant is insufficient. Determine whether. [Structure] A pressure sensor for detecting the refrigerant pressure and a temperature sensor for detecting the temperature of the refrigerant are provided in the middle of a pipe through which the refrigerant circulates. In step 11, the detection signals are read from the temperature sensor and the pressure sensor, in step 12, the map value M is read out based on this detection signal, and in step 13, it is determined from the map value M whether the refrigerant is in the vapor phase state. When it is in the vapor phase state, the routine proceeds to step 15, where the shortage of the refrigerant is notified and the compressor is stopped at step 16. Then, the compressor protection and the lack of the refrigerant are accurately detected.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an air conditioner suitably used as, for example, an air conditioner for an automobile, and more particularly to an air conditioner capable of determining a filling amount of a refrigerant.

[0002]

[Prior Art]

 Generally, automobiles, houses, etc. are equipped with air conditioners such as air conditioners and heaters to supply warm air or cold air to the room.

Here, FIG. 6 shows an air conditioner for an automobile as a conventional air conditioner and will be described.

In the figure, 1 indicates a cooling cycle, and the cooling cycle 1 includes a pipe 2 which forms a circulation flow path through which a refrigerant F such as ammonia and freon gas circulates, and a circulation direction of the refrigerant F 1 in the middle of the pipe 2. It is composed of a compressor 3, a condenser 4 and an evaporator 5 which are sequentially provided along (in the direction of the arrow in the figure), and the heat absorbing surface of the evaporator 5 goes into an operator's cab (not shown). It is supposed to come. On the other hand, the compressor 3 is connected to the engine 6 via an electromagnetic clutch 7 and transmits the rotation of the engine 6 to the compressor 3. The refrigerant F, after being compressed by the compressor 3, undergoes a phase transition from high pressure gas to high pressure liquid to low pressure gas while passing through the condenser 4 and the evaporator 5, and at the same time, from the liquid to the gas in the evaporator 5. At the time of the phase transition, the heat is taken from the cab to cool the cab.

Here, the compressor 3 is connected to the engine 6 via an electromagnetic clutch 7, and the electromagnetic clutch 7 transmits the rotation of the engine 6 to the compressor 3. The electromagnetic clutch 7 is connected by, for example, turning on an air conditioner switch (not shown), transmits the rotation of the engine 6 to the compressor 3, and drives the compressor 3.

A receiver tank 8 is provided between the condenser 4 and the evaporator 5 and is provided in the middle of the pipe 2 for temporarily storing the refrigerant F in a liquid state. A window 8A is provided so that the liquefaction status of the refrigerant F can be visually observed through the viewing window 8A.

Reference numeral 9 is an expansion valve provided between the receiver tank 8 and the evaporator 5 and provided in the middle of the pipe 2. The expansion valve 9 is composed of a pressure reducing valve or the like, and is in a liquid phase state from the receiver tank 8. The refrigerant F that has been discharged as is depressurized to a predetermined pressure and circulated in the direction of arrow A. Then, the refrigerant F decompressed by the expansion valve 9 evaporates while flowing through the evaporator 5, becomes a gas phase state, and is compressed again by the compressor 3.

Further, reference numeral 10 denotes a pressure switch provided between the receiver tank 8 and the expansion valve 9 and installed in the pipe 2. The pressure switch 10 is, for example, a cooling medium pressure P after the refrigerant F is filled. Is closed when the pressure exceeds 2.3 kg / cm ² , the compressor 3 can be driven by turning on the air conditioner switch, and the refrigerant pressure P becomes 23 kg / cm ² by the compressor 3, that is,

[0009]

## EQU1 ## The closure is continued within the range of 2.3 kg / cm ² <P <23 kg / cm ² .

When the refrigerant pressure P becomes 23 kg / cm ² or more, the pressure switch 10 is automatically opened, the electromagnetic clutch 7 is disconnected, and the compressor 3 is stopped. To prevent overpressure condition.

When the refrigerant pressure P drops to 18 kg / cm ² due to the stop of the compressor 3, the pressure switch 10 is closed again,

[0012]

By driving the compressor 3 in Equation 2] ^{18kg / cm 2 <P <23kg} / cm 2 Scope performs excess pressure control of the refrigerant F.

In the air conditioner of the prior art configured as described above, first, when the refrigerant pressure P exceeds 2.3 kg / cm ^{2 according} to the above equation 1 when the refrigerant F is filled, the pressure switch 10 is closed. Then, the compressor 3 can be driven by the air conditioner switch. Then, when the air conditioner switch is turned on in this state, the compressor 3 is driven, and the refrigerant F in the pipe 2 is compressed by the compressor 3 and circulated in the direction of arrow A.

Then, the refrigerant F is condensed while flowing in the condenser 4 to be in a gas-liquid mixed state, and is separated into gas and liquid in the receiver tank 8, and then the refrigerant F in liquid state is expanded. 9 is circulated into the evaporator 5, and the heat in the driver's cab is taken away during evaporation (vaporization) in the evaporator 5 to cool the operator's cab, and a gas phase state is restored to the compressor 3 again. Compressed.

Further, since the compressor 3 is rotationally driven by the engine 6 via the electromagnetic clutch 7, when the rotation of the engine 6 increases, the rotation speed of the compressor 3 also increases and the refrigerant pressure P in the pipe 2 increases. When an excessive pressure is generated in the pipe 2, the pipe 2 or the like may burst or the compressor 3 may be overheated and damaged.

Therefore, when the pressure P of the refrigerant in the pipe 2 becomes an excessive pressure of, for example, about 23 kg / cm ² by the pressure switch 10, the electromagnetic clutch 7 of the compressor 3 is automatically released and the engine 6 is rotated at a high speed. Is transmitted to the compressor 3 to stop the compressor 3 to prevent the compressor 3 from overheating and prevent the piping 2 from bursting. Then, the excess pressure control is performed so that the refrigerant pressure P falls within a predetermined pressure range as shown in the equation (2).

On the other hand, when the filling amount of the refrigerant F in the pipe 2 becomes small due to the refrigerant leakage or the like, the refrigerant pressure P does not rise to the range of the above mathematical expression 2 even if the compressor 3 is continuously driven, Although the compressor 3 cannot be cooled to the desired temperature, the compressor 3 is driven and the compressor 3 is burned.

Therefore, in the pressure switch 10, the refrigerant pressure P is

[0019]

Equation 3] When the P <2.1kg / cm ^2, automatically opened also when the air conditioner switch is turned on, the releasing the connection of the electromagnetic clutch 7, by stopping the compressor 3, complexity during the refrigerant shortage It is designed to prevent seizure of the sushi 3.

[0020]

[Problems to be solved by the device]

 By the way, in the above-described conventional technique, when a refrigerant shortage occurs due to the leakage of the refrigerant F, the refrigerant pressure P falls within the range of the above-described equation 3, the pressure switch 10 is opened, and the compressor 3 is stopped to stop the refrigerant. It detects when there is a shortage. However, in this case, when the filling amount of the refrigerant F is about 10% of that at the time of proper filling, and the cooling efficiency has already dropped significantly, so early detection of refrigerant leakage cannot be performed. There is a problem.

Further, in detecting the proper filling amount at the time of filling the refrigerant F, the operator has made the determination based on the liquefied state of the refrigerant F from the viewing window 8A of the receiver tank 8, but in this method, There is a problem that there is an artificial error, and a constant amount of refrigerant F cannot be filled in the cooling cycle 1 at all times, and an accurate amount of refrigerant filled cannot be detected.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can detect a shortage of the refrigerant filling amount due to a refrigerant leakage at an early stage, and can automatically determine an appropriate filling amount when the refrigerant is filled. The purpose of the present invention is to provide an air conditioner that can be detected automatically.

[0023]

[Means for Solving the Problems]

 The features of the configuration adopted by the present invention to solve the above-mentioned problems are that a pressure sensor is provided in the middle of the flow path to detect the pressure of the refrigerant, and a temperature sensor provided in the middle of the flow path to monitor the temperature of the cooling medium. It is provided with a temperature sensor for detecting, and a refrigerant state determining means for determining the amount of refrigerant charged based on signals from the temperature sensor and the pressure sensor.

[0024]

[Action]

 With the above configuration, it is determined whether the refrigerant is in the proper filling amount or the refrigerant is insufficient by determining whether the refrigerant is in the liquid phase or the gas phase based on the signals from the pressure sensor and the temperature sensor. can do.

[0025]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 11 denotes a pressure sensor provided between the receiver tank 8 and the expansion valve 9 and provided in the pipe 2. The pressure sensor 11 is a diaphragm type pressure sensor, or a piezo element, a semiconductor resistor. It is composed of a pressure sensor using an element or the like, and detects the refrigerant pressure P in the pipe 2.

Reference numeral 12 denotes a temperature sensor provided between the pressure sensor and the expansion valve 9, and the temperature sensor 12 detects the temperature t of the refrigerant F.

Reference numeral 13 denotes a control unit composed of a micro computer or the like, and the control unit 13 is roughly composed of an input / output control circuit 14, a processing circuit 15 and a memory circuit 16. A pressure sensor 11, a temperature sensor 12, an air conditioner switch 17, a changeover switch 18, etc. are connected to the input side of the input / output control circuit 14, and a lamp or the like for notifying the proper filling of the refrigerant F in the pipe 2 at the output side. A proper filling notification device 19 configured by the above, a refrigerant shortage notification device 20 configured by a lamp or the like for notifying when a refrigerant shortage occurs due to refrigerant leakage, and an electromagnetic clutch control circuit 21 for controlling the electromagnetic clutch 7. And are connected. The control unit 13 stores the programs and the like shown in FIGS. 4 and 5 in the memory circuit 16 to perform the refrigerant filling time determination processing and the refrigerant shortage determination processing. Further, the storage area 16A of the storage circuit 16 stores the characteristic map shown in FIG. The changeover switch 18 is selectively switched between when the refrigerant F is filled and when the refrigerant shortage after filling is judged.

A characteristic map based on the relationship between the refrigerant pressure P and the temperature t of the refrigerant F will be described with reference to FIG. The horizontal axis represents the refrigerant pressure P and the vertical axis represents the temperature t.

Reference numeral 22 denotes a saturation curve that represents the boundary line between the liquid phase state and the gas phase state of the refrigerant F. Generally, the lower side of the saturation curve 22 is the liquid phase state and the upper side is the gas phase state. Here, the saturation curve 22 in which the cooling medium F undergoes a phase transition from the gas phase to the liquid phase is set by the relationship between the refrigerant pressure P and the temperature t, the filling amount of the refrigerant F in the pipe 2 is small, and the refrigerant pressure P is When the temperature is low, the refrigerant F is in the gas phase state, and when the amount of the refrigerant F filled is increased and the refrigerant pressure P is increased, the refrigerant F is in the liquid phase state. However, since the refrigerant F is in a gas-liquid mixed state in the vicinity of the saturation curve 22, it is necessary to set determination boundary lines 22A and 22B described later.

That is, reference numerals 22A and 22B denote judgment boundary lines set for the judgment processing, and the judgment boundary lines 22A and 22B are obtained by displacing the saturation curve 22 up and down. , 22B are set to be + 20% and -20% of the proper filling amount of the refrigerant F. The lower side of the determination boundary line 22A is used to determine whether or not the refrigerant F is completely in the liquid phase when the refrigerant is filled, and the upper side of the determination boundary line 22B is completely in the vapor phase when the refrigerant is determined to be insufficient. It is used to determine whether or not the state is reached.

The air conditioner according to the present embodiment has the above-described configuration, and the basic operation thereof is not different from that according to the prior art.

Next, the refrigerant filling determination processing and the refrigerant shortage determination processing by the control unit 13 will be described with reference to FIGS. 4 and 5.

First, the refrigerant filling determination process will be described with reference to FIG.

First, the changeover switch 18 is switched to the refrigerant filling process, and the air conditioner switch 17 is turned on to operate the compressor 3 and at the same time, the filling of the refrigerant F is started from the outside to start the processing operation.

In step 1, the pressure P of the refrigerant F flowing in the pipe 2 and the temperature t of the refrigerant F are read from the pressure sensor 11 and the temperature sensor 12, and in step 2, the map of the characteristic map shown in FIG. Read the value M.

Next, in Step 3, it is determined whether or not this map value M is in a liquid phase state based on the refrigerant pressure P and the temperature t, that is, below the determination boundary line 22A shown in FIG. When it is determined to be “NO”, the filling amount of the refrigerant F filled in the cooling cycle 1 has not reached the proper filling, and therefore, the work of filling the refrigerant F is continued and the step 1 is performed. Return to continue the subsequent processing.

Further, when it is determined to be “YES” in step 3, it can be determined that the filling amount of the refrigerant F filled in the cooling cycle 1 has reached the proper filling, so the process proceeds to step 4, and in step 4, The proper filling notification device 19 is operated to notify the operator that the filling amount of the refrigerant F has reached the proper filling, and this processing is ended. This makes it possible to accurately detect when the refrigerant F is properly filled.

Next, the refrigerant shortage determination process will be described with reference to FIG.

First, the changeover switch 18 is switched to the refrigerant shortage determination process after filling, and the compressor 3 is operated by turning on the air conditioner switch 17 to operate the cooling cycle 1 and start the processing operation.

In step 11, the pressure P of the cooling medium F flowing in the pipe 2 and the temperature t of the coolant F are read from the pressure sensor 11 and the temperature sensor 12, and in step 12, the map value M is calculated in the same manner as in step 2 described above. Read.

Next, in step 13, it is determined whether or not this map value M is in the vapor phase state, that is, whether or not it is above the determination boundary line 22B shown in FIG. When the determination is made, since the filling amount of the refrigerant F filled in the cooling cycle 1 continues to be in the proper filling state, the routine proceeds to step 14, where the proper filling notifying device 19 is continuously operated, and the routine returns to step 11. The subsequent processing is continued.

Further, when it is determined to be “YES” in step 13, it can be determined that the filling amount of the refrigerant F filled in the cooling cycle 1 is insufficient, so the process proceeds to step 15 and the refrigerant shortage notification device is performed. 20 is operated to notify the driver that the filling amount of the refrigerant F in the pipe 2 is insufficient due to refrigerant leakage or the like, and in step 16, the electromagnetic clutch control circuit 21 is operated to prevent the compressor 3 from overheating. A release signal for the electromagnetic clutch 7 is output to the electromagnetic clutch 7, the electromagnetic clutch 7 is released, the driving of the compressor 3 is stopped, and this processing is ended.

With this, it is possible to detect the shortage of the refrigerant due to the leakage of the refrigerant or the like.

Thus, according to this embodiment, the pressure sensor 11 for detecting the refrigerant pressure P 1 and the temperature sensor 12 for detecting the temperature t of the refrigerant are provided in the middle of the pipe 2 in which the refrigerant F is in the liquid phase. Since the control unit 13 that determines the filling amount of the refrigerant F by determining whether the refrigerant F is in the gas phase state or the liquid phase state based on the signals of the temperature sensor 12 and the pressure sensor 11 is provided, Then, the proper filling time of the refrigerant F, which could not be accurately detected, can be accurately detected, and the proper filling notification device 19 can be operated to accurately notify the proper filling time of the refrigerant F.

Further, even when there is a shortage of the refrigerant due to leakage of the refrigerant or the like, it is possible to accurately and quickly detect the shortage of the refrigerant, which could not be detected until the refrigerant F was almost completely exhausted from the inside of the pipe 2. It is possible to operate the notification device 19 to notify it and stop the compressor 3 to suppress the occurrence of overheat and the like, thereby reliably protecting the compressor 3.

It should be noted that, in the above-described embodiment, among the programs shown in FIG. 4 and FIG. 5, step 1 to step 3 and step 11 to step 13 show a concrete example of the refrigerant state determining means which is a constituent feature of the present invention. There is.

Further, in the above-described embodiment, the proper filling notification device 19 and the refrigerant shortage notification device 20 are described as being composed of notification lamps, but instead of this, a notification buzzer, a voice synthesizer, etc. are used. You may be notified by.

Further, although the determination boundary lines 22A and 22B are set to be ± 20% of the proper filling amount of the refrigerant F, the liquid phase state and the gas phase state for determining the proper filling time and the refrigerant shortage are set, for example, It is also possible to arbitrarily set ± 10%, ± 30%, etc. when the refrigerant F is properly filled.

[0050]

[Effect of the device]

 As described above in detail, according to the present invention, a pressure sensor for detecting the pressure of the refrigerant and a temperature sensor for detecting the temperature of the refrigerant are provided in the middle of the piping for the refrigerant, and the signals from the temperature sensor and the pressure sensor are provided. Based on this, it is possible to accurately detect the time when the refrigerant is properly filled by determining whether the filled refrigerant state is the liquid phase state or the gas phase state. Therefore, it is possible to surely detect at an early stage, and it is possible to improve the detection accuracy of the refrigerant state.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a cooling device according to an embodiment of the present invention.

FIG. 2 is a control block diagram showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a characteristic map stored in a storage area of a storage circuit.

FIG. 4 is a flow chart showing a determination process at the time of refrigerant charging.

FIG. 5 is a flowchart showing a refrigerant shortage determination process.

FIG. 6 is a circuit diagram showing a cooling device according to the related art.

[Explanation of symbols]

 1 Cooling Cycle 2 Piping 3 Compressor 4 Condenser 5 Evaporator 6 Engine 7 Electromagnetic Clutch 11 Pressure Sensor 12 Temperature Sensor 13 Control Unit 14 Input / Output Control Circuit 15 Processing Circuit 16 Memory Circuit 16A Storage Area 22 Saturation Curve 22A, 22B Judgment Boundary Line F Refrigerant

Claims (1)

Claims for utility model registration: 1. A flow path through which a refrigerant circulates, a condenser and an evaporator respectively provided in the middle of a pipe forming the flow path, and the condenser and the evaporator. An air conditioner that is provided in the middle of the pipe and is arranged between the compressor and a compressor that compresses the refrigerant in the pipe, and a pressure sensor that is provided in the middle of the flow path and detects the pressure of the refrigerant, and A temperature sensor that is provided in the middle of the flow path and that detects the temperature of the refrigerant, and a refrigerant state determination means that determines the filling amount of the refrigerant based on signals from the temperature sensor and the pressure sensor, Air conditioner to.