JPS63297973A - Refrigeration cycle device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration cycle device, and more specifically,
The present invention relates to a refrigeration cycle device having a function of determining refrigerant shortage or abnormality of an electric expansion valve in a refrigeration cycle device, and is suitable for use in, for example, a refrigeration cycle device of an automobile air conditioner.

<Prior Art> In a refrigeration cycle device, leakage of refrigerant gas occurs due to constant vibrations being applied to piping connections, for example, and accidents such as refrigerant shortage tend to occur. As the refrigerant gas leak progresses, the compressor lubricating oil that circulates with the refrigerant in the refrigeration cycle equipment accumulates in various parts, making it difficult for the lubricating oil to return to the compressor, resulting in compressor seizure. Problems may occur.

Therefore, a conventional approach has been to detect the refrigerant shortage and automatically stop the compressor, and an example of this is a device disclosed in Japanese Patent Application Laid-open No. 194259/1983.

This conventional refrigeration cycle device is equipped with an electric expansion valve, and the input voltage for operating the electric expansion valve is
If the temperature of the refrigerant at the outlet of the evaporator becomes higher than a predetermined temperature while the expansion valve is commanded to be fully open or almost fully open, it is determined that there is a refrigerant shortage and the compressor is stopped.

(Problems to be Solved by the Invention) The above-mentioned conventional technology is configured to detect refrigerant shortage only when the electric expansion valve is fully open or close to fully open, so it is not detected when refrigerant shortage has progressed considerably. There was a problem that refrigerant shortage could not be reliably detected. Therefore, refrigerant shortage cannot be accurately detected at an early point in time, resulting in inefficient operation. Furthermore, with the conventional technology, it is not possible to detect abnormalities in the electric expansion valve, which may also lead to inefficient operation.

An object of the present invention is to overcome these problems of the prior art and provide a refrigeration cycle device that can reliably determine refrigerant shortage or abnormality in the electric expansion valve at an early stage.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a compressor, a condenser connected to the discharge side of the compressor and condensing a gas refrigerant, and a condenser of the condenser. a receiver connected to an outlet side for storing liquid refrigerant; an electric expansion valve connected to the outlet side of the receiver for electrically controlling opening and closing of the valve to depressurize and expand the liquid refrigerant; and this electric expansion valve. connected between the outlet side of the compressor and the suction side of the compressor,
an evaporator that evaporates the refrigerant that has passed through the expansion valve; a pressure sensor that detects the pressure of the liquid refrigerant between the receiver and the electric expansion valve; and a pressure sensor that adjusts the flow of cold W to the evaporator. control means for supplying a pulse waveform input voltage with a variable duty ratio to the electric expansion valve; the control means receives a detection signal from the pressure sensor; A determining means is provided which determines that there is a refrigerant shortage or an abnormality in the electric expansion valve when the value is less than a predetermined value.

(Function) If the refrigerant is properly filled and the electric expansion valve is normal, the detection signal from the pressure sensor will pulsate with a fluctuation range of 6 or more than a predetermined value, for example 1.0 Ky/α2. However, if there is a refrigerant shortage or the electric expansion valve malfunctions, this fluctuation range becomes less than a predetermined value. Since the determination means determines this, the determination result can be used for controlling the model.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, the overall configuration of a refrigeration cycle device suitable for automobile air conditioning is shown.

A variable capacity compressor 1 whose discharge capacity can be changed is driven by an automobile engine (not shown) via an electromagnetic clutch 8. The discharge side of the compressor 1 is connected to the inlet of a condenser 2 by piping, and the condenser 2 transfers the gas refrigerant discharged from the compressor 1 to a cooling fan 1.
It is cooled and condensed by the cooling air blown by 1. The cooling fan 11 is driven by a motor 11a.

An electric expansion valve 4 is connected to the outlet side of the condenser 2 by piping via a receiver 3 that stores liquid refrigerant. This electric expansion valve 4 is electrically controlled in 1 m degree and expands the liquid refrigerant from the receiver 3 under reduced pressure. An example of an electric expansion valve is the above-mentioned Japanese Patent Application Laid-open No. 60-1942.
Since it is disclosed in Japanese Patent No. 59, a detailed explanation of the configuration will be omitted here. An inlet of an evaporator 5 is connected to the downstream side of the electric expansion valve 4.
The two-phase gas-liquid refrigerant that has passed through the electric expansion valve 4 exchanges heat with the air inside the vehicle to evaporate the liquid refrigerant. The outlet of the evaporator 5 is connected to the suction side of the compressor 1 via piping.

A pressure sensor 7 is provided to detect the pressure Pd of the liquid refrigerant in the pipe between the receiver 3 and the electric expansion valve 4. Further, a first refrigerant temperature sensor 9 consisting of a thermistor that detects the refrigerant temperature T, 1 on the evaporator inlet side is arranged on the pipe near the inlet of the evaporator 5, and A second refrigerant temperature sensor 1o consisting of a thermistor is disposed to detect the refrigerant temperature TEo on the steam qz outlet side. Detection signals from the pressure sensor 7 and the first and second refrigerant temperature sensors 9 and 10 are input to the control device 6. The control tlII device 6 controls the detected refrigerant temperatures "Eo and T".
, i, so that the duty ratio D
tfi - Adjust pulse waveform input voltage to electric expansion valve 4
If the fluctuation width of the detection signal from the pressure sensor 7 is less than a predetermined value, it is determined that there is a refrigerant shortage or an abnormality in the electric expansion valve, and the electromagnetic clutch 8 and the motor 1 are
and determining means for cutting off the current being supplied to a.

The control device 6 includes a microcomputer,
A flowchart of the control will be described in detail later.

FIG. 2 shows the relationship between the time t and the liquid refrigerant pressure P detected by the pressure sensor 7 when a proper amount of refrigerant is filled and the electric expansion valve 4 is opened and opened normally. In this case, the liquid refrigerant pressure P is 2
It can be seen that it pulsates with a fluctuation range of ~3Ky1 mouth.

FIG. 3 is a diagram showing the relationship between the time t and the liquid refrigerant pressure P detected by the pressure sensor 7 when the refrigerant is insufficient or the electric expansion valve 4 is abnormal. It can be seen that the pressure Pd changes smoothly without pulsation.

Therefore, by detecting such a phenomenon, it is possible to reliably determine whether there is a refrigerant shortage or an abnormality in the electric expansion valve 4.

The range of fluctuation of the liquid refrigerant pressure Pd varies depending on various conditions (difference between the pressure on the high pressure side and the pressure on the low pressure side, the installation position of the pressure sensor, etc.), but it depends on the duty of the pulse waveform input voltage applied to the electric expansion valve 4. Comparatively, when 0.1<[)t<0.9 and the fluctuation range of liquid refrigerant pressure Pd is 19/l*2 or more, it is determined to be normal, and 0.1<D, <0. 9, if the fluctuation width of the liquid refrigerant pressure Pd remains less than 1 phantom/υ2 for a period of time (for example, 1 minute) or more, it is determined that there is an abnormality (refrigerant shortage or malfunction of the electric expansion valve). To detect the fluctuation width of the liquid refrigerant pressure P, the maximum and minimum values of P are detected every 11 cycles of the electric expansion valve 4 (that is, every cycle w1 of the pulse waveform input voltage), and the difference between them is calculated. Let be the fluctuation range ΔP. −
As an example, the pressure sensor 7 immediately after a voltage signal for switching the electric expansion valve 4 from opening to closing is input to the electric expansion valve 4.
The liquid refrigerant pressure P is determined by taking the difference between the detection signal from the pressure sensor 7 and the detection signal from the pressure sensor 7 immediately after the voltage signal for opening the electric expansion valve 4 is input to the electric expansion valve 4.
A variation range ΔP is used for the cylinder.

In the memory of the microcomputer included in the control device 6, there is tQl for executing the arithmetic processing described below.
tl program is stored in advance.

According to the flowcharts shown in FIGS. 4 and 5, u
The operation of the III device 6 will be explained.

The process starts in step 300, and first, in step 301, it is determined whether the A/C switch for operating the air conditioner II is ON. If the A/C switch is ON, the process proceeds to step 302, where the refrigerant temperature TEi at the evaporator inlet and the cooling tlA lag TEo at the evaporator outlet are read. In step 303, ■. >O('C) is determined,"
If Eo≦0 (° C.), the process proceeds to step 304, where the energization to the electromagnetic clutch 8 is cut off, and the process returns to step 301.

If TEo>O (° C.), the process proceeds to step 305 and it is determined whether or not the electromagnetic clutch 8 is energized. If the electromagnetic clutch 8 is not energized, the process proceeds to step 306, where it is determined whether TEo>10 (°C), and the TE
If o≦10 (° C.), return to step 301 and T.

If >10 (℃), proceed to step 307? 1i1
a Electrify clutch 8.

When it is determined in step 305 that the electromagnetic clutch 8 is energized, or after the process in step a3 is performed in step 307, the duty ratio Dt is calculated.

To calculate the duty ratio Dt, in step 308, E""Eo'Ei-Eno is first calculated. E here. 0 is a constant that gives the desired temperature difference, and E
, is the deviation between the actual refrigerant temperature difference (T, o-T, .) at the inlet and outlet of the evaporator 5 and the desired temperature difference (Eoo). Next, in step (309), the already calculated E. , the duty ratio Dt is the following P
It is calculated using the IDfil161 formula.

Here, K, T, and 'rD are constants determined in advance through experiments or the like. The pulse waveform input voltage having the duty ratio calculated in step 309 is
Immediately after the voltage signal that opens the electric expansion valve 4 from Iff to Iff is output, and immediately after the voltage signal that opens the electric expansion valve 4 from Iff to Iff is output, the pressure hinge is The liquid refrigerant pressure P from I-7 is read.

The liquid refrigerant pressure P is measured as shown in FIG.
This is carried out by interrupting the control flowchart, and the detection signal from the pressure sensor 7 is subsequently received and stored in the memory. When the interrupt is released, the fluctuation range ΔP is determined in step 310 using the measured value of Pd stored in the memory.

Next, the process proceeds to step 311, and it is determined whether 0.1<Dt<0.9. If D is not within this range, the process returns to step 301, and if Dt is within this range, the process returns to step 301. Proceed to step 312 and check ΔPd≧1.0 (N9/
ca+). ΔP, ≧1
．． If it is 0 (K9/cIR), it is determined that it is normal, so the process returns to step 301 and the same process as described above is repeated. Step 3
If Δpd<i, 0 (υ/1) in step 12, it means that either there is a shortage of refrigerant or the electric expansion valve is abnormal, so proceed to step 313 and close the electromagnetic clutch 8.
Cut off the power to. At this time, the power supply to the motor 1a of the cooling fan 11 is also cut off.

Then, the process proceeds to step 314, which is END, so that the failed part can be repaired.

In the description of the above embodiments, a variable volume υ type compressor is used as the compressor 1, but there is no need to limit it to this, and a constant volume polymorph type may also be used. In addition, the duty ratio is adjusted so that the difference between the detection signal from the second refrigerant temperature sensor o and the detection signal from the first refrigerant temperature sensor 9 is adjusted to a desired value. Adjustment of , can be carried out in a variety of ways. For example, the duty ratio Dt can be adjusted by control as disclosed in Japanese Patent Laid-Open No. 60-194259 mentioned above.

Furthermore, although the case where the control unit including the control means and the determination means is entirely constructed using a microcomputer has been described, it is also possible to construct each of the above means by an electric circuit that is a combination of individual electric circuit elements. Of course it is possible to do so.

The timing of detecting the liquid refrigerant pressure Pd does not need to be limited to immediately after closing from between the electric expansion valves and from closing to opening as described in the above embodiments. For example, the detection signal of the pressure sensor may be continuously detected. Alternatively, the maximum value and minimum value may be detected.

Further, the present invention is not limited to use in automobile air conditioning, but can be widely applied to refrigeration cycle devices for various uses.

(Effects of the Invention) The present invention makes it possible to reliably detect refrigerant shortage or abnormality of the electric expansion valve at an early stage, thereby preventing the refrigeration cycle device from operating inefficiently. Therefore, the present invention is practically very effective in terms of ensuring the durability of the compressor and the cooling capacity of the refrigeration cycle device.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a refrigerating Nicle device for an automobile air conditioner, which is an embodiment of the present invention, and FIGS. 2 and 3 show changes in liquid refrigerant pressure P. In the normal case, FIG. 3 is a diagram showing a case in which there is a refrigerant shortage or an abnormality in the electric expansion valve, respectively, and FIGS. 4 and 5 are flowcharts illustrating control by a microcomputer of the 11iII device. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Condenser, 3... Receiver, 4... Electric expansion valve, 5... Evaporator, 6... Control TLL device, 7... Pressure sensor, 8... Electromagnetic clutch, 9... First refrigerant temperature sensor, 10... Second refrigerant temperature sensor, 11... Cooling fan, 11a... Motor.

Claims (1)

[Claims] (1) (a) a compressor; (b) a condenser connected to the discharge side of the compressor to condense gas refrigerant; (c) a receiver connected to the outlet side of the condenser to store liquid refrigerant; (d) an electric expansion valve that is connected to the outlet side of the receiver and electrically controls opening and closing of the valve in order to decompress and expand the liquid refrigerant; (e) an outlet of the electric expansion valve and an intake of the compressor; (f) a pressure sensor that detects the pressure of the liquid refrigerant between the receiver and the electric expansion valve; ) control means for supplying a pulse waveform input voltage with a variable duty ratio to the electric expansion valve in order to adjust the flow rate of refrigerant to the evaporator; A refrigeration cycle device characterized by comprising a determining means that receives a signal and determines that there is a refrigerant shortage or an abnormality in an electric expansion valve when the fluctuation range of the detection signal is less than a predetermined value.