JPS61197970A - Protective device for compressor of refrigerator - 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 an improvement in a compressor protection device that forcibly stops the compressor in order to prevent the compressor from burning out when there is a shortage of refrigerant in the refrigerator. .

(Prior Art) Generally, when a refrigerant shortage occurs due to a refrigerant leak or the like in the refrigerant circuit of a cold 2I1 machine, the evaporation pressure decreases and the discharge gas temperature increases accordingly, reducing the refrigerating effect. As the refrigerant shortage progresses, the compressor is overheated and the lubricating oil is carbonized due to an abnormal rise in the discharge gas temperature, making it easy to burn out the compressor. Therefore, when there is a shortage of refrigerant, it is necessary to forcibly stop the compressor to protect it.

For this reason, conventionally, for example, in the device disclosed in Japanese Patent Publication No. 59-32675, a low pressure switch that responds to the evaporation pressure is provided, and the low pressure switch is opened and closed as soon as the evaporation pressure drops below a predetermined set value. The compressor is forcibly stopped based on the opening operation of the compressor. Also, Unexamined Japanese Patent Publication No. 591
The device disclosed in Japanese Patent No. 91858 is provided with a temperature detection means for detecting the temperature of the discharged gas, and the compressor is forcibly stopped when the humidity of the discharged gas exceeds a set value.

(Problem to be Solved by the Invention) However, in each of the above conventional examples, the set values of the evaporation pressure and discharge gas temperature, which are the criteria for forced stop of the compressor, are set to prevent burnout of the compressor in order to prevent malfunction. Since the value is set to a value corresponding to the previous value, there is a problem that overheating of the compressor and carbonization of the lubricating oil have progressed considerably in the process until the compressor is forcibly stopped.

Therefore, in order to alleviate the above problem, the compressor protection is configured in two stages so that a warning can be issued at an early stage of refrigerant shortage before the compressor is forced to stop, so that maintenance can be performed early on in response to refrigerant shortage. It is possible to do so.

However, in that case, when configuring the above two-stage compressor protection using two low-pressure H-closers, ■ it will lead to higher costs, and ■ it will cause errors because the fluctuations in evaporation pressure are relatively large even during normal operation. ■ Load fluctuations also cause fluctuations in evaporation pressure, making it difficult to determine whether the warning is due to overload or lack of refrigerant ■ Because it is necessary to consider the differential of the low-pressure pressure switch, two-stage fixed value There are inconveniences such as restrictions on settings.

On the other hand, when configured using two discharged gas temperature detection means, the discharged gas
Since this causes a fluctuation in t, there is an inconvenience that it is difficult to determine the meaning of the warning.

The present invention has been made in view of this point, and in addition to the above-mentioned evaporation temperature and discharge gas temperature, the degree of superheating of the refrigerant is a factor that changes depending on the refrigerant shortage, and the characteristics of this degree of superheating are affected by load fluctuations. The aim is to provide the above two-stage compressor protection with a warning based on the degree of superheat, and a warning based on at least one of the evaporation temperature, discharge gas temperature, and degree of superheat. By configuring this system with a forced stop of the compressor, a warning is issued before the compressor is forced to stop and only when there is a shortage of refrigerant, making early maintenance possible at low cost. The purpose is to improve the reliability of the compressor by quickly eliminating the overheating of the compressor and the progress of carbonization of lubricating oil, which cause burnout of the compressor.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention, as shown in FIG. The compressor protection device includes a first detection means (12) that detects the degree of superheat of the refrigerant, and receives the output of the first detection means (12) and detects when the degree of superheat is equal to or higher than a warning side setting value corresponding to an initial refrigerant shortage. and a warning signal output means (15) for outputting a warning signal to remind replenishment of the refrigerant. Further, the second detection means (13) detects at least one of the evaporation temperature of the refrigerant, the discharge gas temperature, and the degree of superheat, and the output value of the second detection means (13) is received and the output value is determined by the compressor (1). ), the stop signal output means (16) outputs a stop signal for forcibly stopping the pressure wJIIl<1) when the pressure wJIIl<1 is above the set value on the forced stop side corresponding to immediately before burnout.

(Function) As described above, in the present invention, when there is an initial refrigerant shortage when the degree of superheat reaches the warning side setting value or more, the warning signal output means (15)
Since a warning signal is output from the refrigerant to remind replenishment of refrigerant, early maintenance in case of refrigerant shortage becomes possible at a low cost, and overheating of the compressor (1) and progress of carbonization of lubricating oil can be quickly resolved. be able to. Moreover, since the detection of the initial refrigerant shortage is performed based on the degree of superheat, which has relatively little fluctuation with respect to load fluctuations, WAvJ fluctuations due to load fluctuations are reduced, and the detection accuracy is improved.

Further, when refrigerant shortage progresses immediately before compression 1jJ (1) burns out, at least one of the evaporation temperature of the refrigerant, the discharge gas temperature, and the degree of superheat reaches a predetermined value for forced stop, and the stop signal output means (16) Since a stop signal for the compressor (1) is output, the compressor (1) is forcibly stopped and its burnout can be reliably prevented.

(Example) Hereinafter, an example of the present invention will be explained with reference to the drawings from FIG. 2 onwards.

(First embodiment) Figure 2 shows the overall configuration of a refrigerator, where (1) is a compressor, (1) is a compressor, (
2) is a condenser installed outdoors, (3) is an expansion mechanism, and 4) is an evaporator, and each of the devices (1) to (4) is connected to a refrigerant pipe (5). A closed circuit (6) is formed by connecting the refrigerant so that the refrigerant can circulate, and by circulating the refrigerant discharged from the compression Ia (1) as shown by the arrow in the figure, the amount of heat contained in the refrigerant is transferred to the condenser (2). After being released outdoors, the evaporator (4) repeatedly absorbs heat from the air inside the room or in the refrigerator, thereby cooling the room or freezing or refrigerating the stored items in the refrigerator.

In addition, <7) in the figure is an accumulator.

(8) also controls the operation of the pressure IllI machine (1).
□The compressor control circuit (ku) is installed in the evaporator (ku), and the evaporation temperature sensor (10) is a thermistor or the like that detects the evaporation temperature Te of the refrigerant.
) A suction gas temperature sensor (11) is installed in the upstream refrigerant pipe (5) and detects the humidity T1 of the refrigerant suction gas into the compressor (1); 5
) is installed in the compressor (1) and detects the temperature T2 of the discharge gas from the compressor (1), and the temperature difference (T+ -Te ) In other words, it constitutes the first detection means (12) for detecting overheating rI3SH, and the evaporation temperature sensor (9) and discharge temperature sensor (11) detect the evaporation temperature (Te) and discharge of the refrigerant. a second detection means (13) adapted to detect the gas temperature (T2);
).

The three temperature sensors (9) to (11) are each connected to a refrigerant shortage detection circuit (14) so as to be able to send and receive signals, and the refrigerant shortage detection circuit (14) causes the compressor control circuit ( A stop signal for the compressor (1) is output to the refrigerant (1) to forcibly stop the compressor (1) when there is a shortage of refrigerant.

Inside the refrigerant shortage detection circuit (14), as shown in FIG. Compression 1 when the refrigerant shortage progresses, which corresponds to just before burnout.
Two circuits are provided: a stop signal output circuit (16) as a stop signal output means for outputting the forced stop signal of No. 11(1).

First, the warning signal output circuit (15) will be explained.
(20) receives the outputs of the evaporation temperature sensor (9) and the suction gas temperature sensor <10), and receives the difference (T1-Te) between the evaporation temperature Te and the suction gas hot water level T+, that is, the superheat r! IS
This is an arithmetic circuit that calculates H by PI4. Here, as shown in Fig. 5, the degree of superheating SH has a characteristic that it gradually increases as the amount of refrigerant decreases, that is, as the refrigerant shortage progresses, and also has a characteristic that changes relatively little with respect to load fluctuations (not shown in the figure). ). Further, as can be seen from the figure, the refrigerant evaporation m a T e has a characteristic that it gradually decreases as the refrigerant shortage progresses, and the discharge gas depletion T z has a characteristic that it gradually increases. In addition, (21) is a first reference value setting device that presets and stores the degree of superheating SHs corresponding to the initial refrigerant shortage when the refrigerant amount is 70% as shown in FIG. The degree of superheating SH from the arithmetic circuit (20) and the warning side set value S of the first reference value setter (21>)
This is a first comparator that inputs the signal Hs and Hs to the sampling timer (23) every time the sampling time T elapses, compares the magnitude, and outputs a refrigerant shortage detection signal when the degree of superheating SH is equal to or higher than the warning side setting value SHs. Further, (24) is incremented by one every time the refrigerant shortage detection signal is received from the first comparator (22), and when the count reaches a predetermined number N, the first comparator (24) allows the passage of the refrigerant shortage detection signal. Counter, (2
5) is a relay circuit which internally has a warning side relay (RYE) and a forced stop relay (RY2), and when it receives the refrigerant shortage detection signal from the first counter (24), the warning side relay (RY+) is activated. ) switching contact (RYl-1)
has the function of switching from the OFF side to the ON side and outputting a warning signal, and this warning signal causes, for example, a warning buzzer (not shown) to sound or a warning lamp to light up to remind replenishment of refrigerant. It is made to be.

In addition, in the stop signal output circuit (16), as shown in FIG. a second reference value setter for storing preset values as side set values;
27) is the first comparator (
22), the second comparator (22) is similar to the second comparator (22);
7) calculates the evaporation temperature Te signal from the evaporation temperature sensor (9) and the first forced stop side set value Tes of the second reference value setter (26) every 1fflT during sampling by the sampling timer (23). Input, compare the sizes, and set the evaporation temperature Te to the first forced stop m! When the temperature is 11T88 or higher, a refrigerant shortage detection signal is output.

Furthermore, (28), like the second reference value setting device (26), sets the discharge gas region TzS (see FIG. 5) immediately before the burnout of the compressor (1) with a refrigerant amount of 50 to 60% to the second value. a 311th quasi-value setter that stores the forced stop side set value in advance;
29) is the discharge gas temperature T2 signal from the discharge gas temperature sensor (11) and the second value of the third!1 quasi-value setting device (28).
Forced stop side setting (*T2S and the above second comparator (27)
In the same way, input the sampling timer (23) every time the sampling time T elapses, and compare the sizes to determine the discharge gas temperature T.
2 is a third comparator that outputs a refrigerant shortage detection signal when the value T2S is greater than or equal to the first forced stop side set value T2S. And the second above
．． The refrigerant shortage detection signals of the third comparators (27) and (29) are sent to the relay circuit (25) via the second counter (30) and third counter (31), which are similar to the first counter (24), respectively. At the same time, the relay circuit (25) is connected to the switching contact (RY2) of the forced stop relay (RY2) upon receiving one or both of the refrigerant shortage detection signals.
RYz −+ ) is switched from the OFF side to ONllm and the stop signal of the compression l1N (1) is sent to the compressor control circuit.
8).

Therefore, in the above embodiment, when a refrigerant shortage occurs in the closed circuit (6) due to refrigerant leakage during operation, the superheating blow SH gradually increases as shown in FIG. 5, and the cooling tii reaches 70%. When the initial refrigerant shortage occurs, the degree of superheating SH reaches the warning side set value SH8, and a warning signal is output from the warning signal output circuit (15). As a result, for example, a warning buzzer or the like will sound or a warning lamp will light up to remind you to replenish the refrigerant, making it possible to perform early maintenance to prevent refrigerant shortages well before the compressor burns out. Compression 1 causes burning of compression Im(1)! (1) Overheating and progress of carbonization of raW4 oil can be eliminated at an early stage. Moreover, in this case, since the superheat characteristic has relatively little variation with respect to load fluctuations, a warning signal can be output only when there is a refrigerant shortage, which reduces malfunctions due to load fluctuations and improves the detection accuracy of refrigerant shortages. You can improve your performance. In addition, the degree of superheat (
Since the detection of SH is comprised of an evaporation temperature sensor (9) and an intake gas temperature sensor (10), it is possible to reduce costs.

In addition, when continuing operation after the above warning, the refrigerant evaporation temperature Te and the discharge gas concentration T2 fluctuate with load fluctuations and change as the refrigerant shortage progresses, and the refrigerant amount decreases to 50%.
When the compressor (1) reaches ~60% and is about to burn out, its evaporation humidity Te or discharge gas temperature T2 reaches the corresponding forced stop side set value TO3 or TzSk, and the stop signal output circuit (16) A stop signal for the compressor (1) is output from the compressor control circuit (8). As a result, compression 11i(1)
is stopped for 11J, and burnout caused by the lack of refrigerant is reliably prevented.

Further, in the above embodiment, the refrigerant shortage detection circuit (14) was configured using an electronic circuit, but instead of this, it may be configured using a microcomputer 1-1 having a built-in CPU, etc. A flowchart showing the control details is shown in FIG. That is, in the initial refrigerant shortage detection flow shown in FIG.
), the evaporation temperature Te signal from the evaporation temperature sensor (9) is read in step S2, and the refrigerant superheat degree SH (=T
+ −Te ) is calculated. After that, in step S4, the superheating degree SH is set to the warning side (* Compare the size with SH8,
If H≧SHs (YES) indicates a refrigerant shortage, in step S5, +°1 is added to the number of refrigerant shortage detections, and this is compared in magnitude with a predetermined number of times N in step S6. And still KI
In the case of NO in N, in the case of non-refrigerant shortage of SH<SHs in step S4, the process returns to step S1 after the sampling time T has elapsed in step S7, and while repeating the above operation, K+ -N is reached. If the answer is YES, a warning signal is output in step S8 to remind replenishment of the refrigerant.

In addition, in the first and second forced stop flows in FIGS. I
At step I, the evaporation temperature Te signal from the evaporation temperature sensor (19) and the discharge gas temperature lower 2 signal from the discharge gas waterfall sensor (11) are read, and at step 32' + S2'', these are set to the first and second forced forces, respectively. Stop side setting value 7es, T
z Compare the size with S. And 7e≦Tes, Tz≧
If T2S is YES, if refrigerant is insufficient, step S3', 83
'' adds 2 to the number of refrigerant shortage detections and ``1°'' to Ks, and these are added to the predetermined number of times N in step 84 ' + 84''.
Compare the size with
, step 85' together with the non-refrigerant shortage case where T2 < T2S.

At step S5'', the above operation is repeated after the sampling time T has elapsed, and if YES is reached when 3=N at K2-N, the compressor (1) is changed at steps S, J, S, and 1'. A stop signal is output to forcibly stop the compression 111(1) to prevent its burnout.Therefore, similarly to the above embodiment, the initial refrigerant shortage detection flow shown in FIG.
compressor (1), which would cause burnout of the compressor (1).
It is possible to quickly and reliably eliminate overheating of the oil and carbonization of the WJ oil.

(Second Embodiment) Furthermore, FIG. 6 shows a second embodiment of the present invention, and FIG.
In the large embodiment, instead of forcing the compressor (1) to stop based on the evaporation temperature Te and the discharge gas temperature T2, it is done based on the degree of superheat SHk:m.

That is, in the figure, the second detection means (13') is used as the evaporation temperature sensor (9) and the suction gas humidity sensor (10) (that is, the first detection means (12)), and the refrigerant shortage detection circuit ( 14') stop signal output circuit (16')
The forced stop side set value of the second reference value setter (26') is set to the overheating level 13 immediately before burnout of the compressor (1), which corresponds to a refrigerant shortage of 50 to 60% as shown in FIG.
iSH3z and the second comparator (27'
) and the degree of superheating S) from the arithmetic circuit (20)! The signal is compared in magnitude with the forced stop side set value 5H3z of the reference value setter (26'), and when SH≧5HS2 is reached, the second comparator (26')
Based on the refrigerant shortage detection signal from 27'), the switching contact (RY2-+) of the forced stop side relay (RY2) of the relay circuit (25) is turned OFF via the second counter (30').
The stop signal for the compressor (1) is output by switching from the side to the ON side. The other configurations are the same as those of the first embodiment. Therefore, as in the first major embodiment, a warning based on overheating 1 SH when there is initial refrigerant shortage, and a warning based on pressure 4
1iI machine (1) was forced to stop just before it was burnt out; and 2.
Stage compressor protection can be ensured.

In the first embodiment, the compression 111(1) is forcibly stopped based on both the evaporation temperature rliTe and the discharge gas temperature T2, and in the second embodiment, it is carried out when the overheating l5)-1 is reached. However, it may also be performed based on only one blowing signal of the evaporation temperature Te or the discharge gas temperature T2, or based on a combination of these and the degree of superheating SH. The forced stop in 1) may be performed based on at least one of the evaporation temperature 7e, the discharge gas temperature T2, and the degree of superheat S1-1.

Further, as the expansion mechanism [3] in the above embodiment, an electric superheating expansion valve is used, and the evaporation temperature sensor (9) and the intake gas! If the evaporation temperature Te signal and the intake gas temperature lower 1 signal detected by the +1 sensor (10) are used as valve control inputs, the cost of the refrigerator can be further reduced.

Furthermore, in the above embodiments, cooling and freezing are used.

Alternatively, although an example of a refrigerant circuit that performs only refrigeration has been shown, the present invention is not limited to this, and can also be applied to a heat pump type refrigerator using a four-way switching valve.

(Effects of the Invention) As explained above, according to the present invention, when there is an initial refrigerant shortage, a warning signal is output based on the degree of superheating of the refrigerant, and when the refrigerant shortage progresses immediately before the compressor burns out, the evaporation temperature of the refrigerant is Compressor protection is configured in two stages by forcibly stopping the compressor based on at least one of the discharge gas temperature and the degree of superheating, so it protects the compressor from burnout due to refrigerant shortage while also preventing initial refrigerant shortage. It is possible to detect the timing with high precision and at low cost, and to quickly eliminate the causes of compressor overheating and carbonization of lubricating oil, which can cause burnout, at a stage well before compressor burnout, thereby increasing reliability. It is possible to improve this.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 5 show a first embodiment of the present invention, and a second embodiment of the present invention is shown in FIG.
Figure 3 is an electronic circuit diagram showing the internal configuration of the refrigerant shortage detection circuit, Figure 4 is a flowchart diagram showing a modification of the refrigerant shortage detection circuit, and Figure 5 is a diagram showing the refrigerant amount. FIG. 6 is an electronic circuit diagram of a refrigerant shortage detection circuit showing a second embodiment of the present invention. (1)...Compressor, (6)...Closed circuit, (9)...
・Evaporation temperature sensor, (10)...Suction gas temperature sensor, <11)...Discharge gas temperature sensor, (12)...
First detection means, (13), (13')...Second detection means, (14), (14')...Refrigerant shortage detection circuit,
(15)...Warning signal output circuit, (16), <16'
>...Stop signal output circuit, (21)...First reference value setter, (26), (26')...Second reference value setter, (28)...Third reference value Setting device.

Claims (1)

[Claims] (1) A compressor protection device for a refrigerator configured to forcibly stop a compressor (1) in the event of refrigerant shortage, which comprises a first detection means (12) for detecting the degree of superheat (SH) of the refrigerant; 1
Warning signal output means (15) receives the output of the detection means (12) and outputs a warning signal to remind replenishment of refrigerant when the degree of superheating (SH) is equal to or higher than a warning side set value (SH_s) corresponding to the initial refrigerant shortage. In addition, the refrigerant evaporation temperature (Te), discharge gas temperature (T_2), and superheat degree (SH
); and a forced stop side setting value that receives the output of the second detection means (13) and whose output value corresponds to immediately before burnout of the compressor (1). (T
es), (T_2s), (SHs_2) or more, a stop signal output means (16) for outputting a stop signal for forcibly stopping the compressor (1). .