JPH0452620Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for simply and accurately determining refrigerant shortage in compression type refrigeration equipment, particularly in compression type heat pump air conditioners.

[Conventional technology]

In all types of refrigeration equipment that form heat pumps through condensation and evaporation of refrigerant, it is necessary to prevent performance degradation and failure due to lack of refrigerant. This is because, in the case of compression type refrigeration equipment, the overwhelming majority of failures are due to a lack of refrigerant, such as compressor damage or expansion valve failure.

Therefore, in the past, when a refrigerant shortage occurs, measures have been taken to forcefully stop the equipment and prevent damage to the compressor, etc. by installing a protection circuit such as a high-pressure cut or a motor protection thermostat. It is taken.

Conventional methods for determining refrigerant shortage in compression refrigeration equipment include measuring the actual pressure using a high-pressure and low-pressure gauge, and determining the overload state of the compressor from the measured current value of the compressor during operation. is the most common.

Furthermore, depending on the equipment, a gas temperature detector is installed to detect the temperature of the gas discharged from the compressor, and if this gas temperature exceeds a certain value (for example, 120°C), it is determined that there is a refrigerant shortage. There are also known methods.

Also, Japanese Patent Application Laid-Open No. 55-31215 and Utility Model Application No. 55-31215
Japanese Patent No. 85672 discloses an invention that attempts to detect refrigerant leakage by photoelectrically detecting bubbles in a refrigerant liquid pipe.

[Problem that the invention attempts to solve]

When a protection circuit is used to stop equipment when a refrigerant shortage occurs, there is a problem in that the equipment also stops due to other causes. For example, a decrease in heat exchange efficiency due to other causes in the condenser or evaporator, abnormally high or low temperature of the outside air temperature or secondary heat medium, abnormal increase in secondary side load, malfunction of the expansion valve, clogging of the strainer, etc. Depending on the cause, the protection circuit may activate and force the equipment to stop. Therefore, it is necessary for an expert in the field to investigate the cause of the stoppage, and it is also necessary to separately determine whether the equipment has stopped due to a lack of refrigerant.

Generally, equipment malfunctions due to refrigerant shortages will not occur until most of the refrigerant stored in the equipment or piping system has been drained, so even experts need to be able to predict refrigerant shortages before an abnormal shutdown occurs. is practically impossible. For this reason, even if the equipment is operating with a lack of refrigerant, the user will not notice the abnormality until the equipment has stopped, and even if the equipment has stopped, the cause may not be known, so the user may repeatedly restart the equipment, resulting in There were many cases where compressor motors were burnt out.

Furthermore, among the conventional refrigerant shortage determination methods, when pressure measurement is performed using a gauge, it is necessary to perform pressure measurement when the equipment is abnormal, and the determination cannot be made after the equipment is stopped, making reproducibility difficult. There is also the problem that only an expert can make a determination. Similarly, when measuring the current value of the compressor, an expert on the equipment is required.
Furthermore, since the determination method based on refrigerant discharge temperature detects overheating of the compressor from the refrigerant temperature, it can only serve as an indirect guide.

Therefore, it has been practically impossible to predict refrigerant shortages to prevent failures using conventional discrimination methods.

The method proposed in Japanese Patent Application Laid-Open No. 55-31215, which uses a light-emitting element and a light-receiving element to detect the occurrence of bubbles in a refrigerant liquid, is particularly suitable for devices that operate 24 hours a day, such as refrigerators and freezers. Although it is considered to be useful, it cannot be started, stopped, or controlled automatically like an air conditioner.
For machines that repeat unload operation (no-load operation) on a minute-by-minute basis, the system detects air bubbles caused by the operating conditions that occur at the start or immediately after unloading, rather than from a lack of refrigerant, resulting in frequent false alarms. It is thought that there is a risk of

On the other hand, in the case of Japanese Utility Model Application No. 55-85672, even if the amount of refrigerant is appropriate in a car cooler, bubbles may be generated during low-speed operation, so the pulse generated by the ignition coil exceeds a certain value. Although they sometimes disclose a device to put the photodetector in an operating state,
Although this is successful in automobile coolers, it cannot be applied to ordinary air conditioning.

The present invention aims to solve such problems and provides a device that can accurately monitor whether or not there is a shortage of refrigerant in the air conditioner of a heat pump during air conditioning.

[Means to solve problems]

This invention is a heat pump type air conditioner in which refrigerant compressed by a compressor is condensed and liquefied in a condenser, gasified in an evaporator via an expansion valve, and then circulated to the compressor. A viewing window made of a light-transmitting material is provided on the wall of the refrigerant pipe leading to the pipe, and a photoelectric switch is attached to the outside of the viewing window so that light passes through the viewing window and into the liquid refrigerant in the pipe. When the photoelectric switch detects the presence of air bubbles in the liquid refrigerant passing through the pipe at a time other than immediately after the start of the heat pump device, immediately after unloading, and immediately after the end of the heat pump device, it is determined that there is a refrigerant shortage. This is a refrigerant shortage determination device for heat pump air conditioners.

In other words, the present invention detects air bubbles that occur when there is a shortage of refrigerant when the liquid refrigerant condensed in the condenser flows toward the expansion valve, but this is not the case with general air conditioning heat pump devices. Although the design is such that the refrigerant is completely liquefied in the condenser and flows to the expansion valve (without entrained air bubbles) depending on the air conditioning load, the condenser is If the function of the photoelectric switch is not up to the normal level or the condenser function is in the stopped stage, bubbles will inevitably occur when passing through the condenser, so the photoelectric switch should not be activated at other times. When the presence of bubbles in the liquid refrigerant passing through the pipe is detected, it is determined that there is a refrigerant shortage.

Entrainment of air bubbles in the liquid line can be determined by a photoelectric switch. For example, when using a reflective photoelectric switch that has a light emitter and receiver in one location, the light emitted from the light emitter is scattered by bubbles and a portion of it is input to the light receiver, making it difficult to detect the presence of bubbles. can. Therefore, if the presence of air bubbles is continuously monitored by a photoelectric switch while the equipment is in operation, a light reception signal indicating the presence of air bubbles will be detected even at times other than immediately after the start, immediately after unloading, and immediately after the end as described above. If this continues to be input, it means that a refrigerant shortage has occurred.

Note that "immediately after the end" means immediately after the operation of the heat pump device itself has stopped, that is, immediately after the rotation of the compressor and the blower has stopped. If a circuit is provided to link the start/stop of the heat pump device and the start/stop of the detection operation by the photoelectric switch, the detection operation can be stopped after the end until the start. There are cases where it is complicated to separately install the detection circuit in the pump device, and there are cases where it is convenient to keep the detection circuit online at all times when centrally managing a large number of air conditioners and heaters. In such a case, the period immediately after the end is not subject to determination of refrigerant shortage.

In principle, the photoelectric switch used in the device of the present invention can be a transmission type or a mirror type in addition to the above-mentioned reflection type, but a reflection type allows more accurate discrimination. In addition, the device of the present invention can be applied to any type of compression heat pump device that repeats liquefaction and vaporization, and the type of refrigerant can be used not only ordinary fluorocarbon-based ones but also those that liquefy and vaporize. In principle, it is applicable regardless of its type.

The present invention will be explained in detail below with reference to the embodiments shown in the drawings.

Figure 1 schematically shows the refrigerant shortage determination device of the present invention, where 1 represents the compressor, 2 the condenser, 3 the expansion valve, and 4 the evaporator. The high-pressure refrigerant condenses and radiates heat in the condenser 2, liquefies it, passes through the expansion valve 3, gasifies it in the evaporator 4, removes heat, and is transferred to the compressor 1.
The figure shows the refrigeration cycle of a normal air conditioning compression refrigeration equipment. In the device of the present invention, a viewing window 6 is formed in the liquid pipe line 5 from the condenser 2 to the expansion valve 3 in this refrigeration cycle. In the illustrated embodiment, a pipe 8 with a transparent glass 7 fitted onto one side of the pipe wall in advance is inserted into the liquid pipe line 5.
A viewing window 6 is formed in the liquid pipe line 5. A light emitting/receiving device 9 of a reflective photoelectric switch is attached near the glass 7 on the outside of the viewing window 6. The light emitting/receiving device 9 projects light from its internal light emitter through the glass 7 to the liquid pipe line 5, and if there are bubbles in the refrigerant liquid in the liquid line 5, the light hits the bubbles and is scattered.
A part of the scattered light is reflected by the light receiver in the light emitting/receiving device 9. Therefore, by detecting this reflected light, the presence of bubbles can be detected.

Reference numeral 10 indicates an amplifier unit, which inputs the light receiving input of the light emitting/receiving device 9 through an optical fiber 11, and when the light is received,
ON, and if no light is received, it changes to an OFF electrical signal and outputs it. This output is sent to the display panel of the equipment operation section or the display panel 12 of the central monitoring room, where:
When a signal indicating refrigerant shortage is input, it is output to an alarm or indicator light. Note that 13 represents a power source and a switch box.

Figures 2a and 2b are time charts showing typical examples of signals output from the amplifier unit 10. In a, there is no refrigerant shortage; b
indicates a case where a refrigerant shortage has occurred. In other words, when the photoelectric switch detects air bubbles in the liquid, it outputs an ON signal as shown by the hatching in the figure, but even if the device is operating normally as shown in a, it will take several seconds or tens of seconds immediately after starting or unloading. , and for several tens of seconds immediately after the end, bubbles will be present for the reason mentioned above, so the ON
Output a signal. However, at times other than this, if there is no refrigerant shortage, the OFF signal is output. On the other hand, if a refrigerant shortage occurs in b.
The ON signal is output even during normal operation, except immediately after the start, immediately after unloading, and immediately after the end.
Therefore, it is also possible to determine whether or not a refrigerant shortage has occurred using patterns a and b as representative examples.

For this determination, it is possible to input the above-mentioned output signal into a microcomputer that has stored the pattern and automatically perform the determination.In this case, it is possible to perform centralized automatic management by inputting it to this microcomputer from a large number of devices. . Additionally, if it is determined that there is a refrigerant shortage, it can be output to a protection circuit to automatically shut down the equipment.

As described above, according to the present invention, refrigerant shortage in compression type refrigeration equipment can be detected directly, accurately and quickly even during operation, and equipment failure can be prevented beforehand. In a building or the like where a large number of devices are present, a failure prediction device is provided which is extremely useful for centrally managing the operating status of each device.

[Brief explanation of the drawing]

FIG. 1 is an equipment layout diagram of a refrigerant shortage determination device according to the present invention, and FIGS. 2a and 2b are temporal pattern diagrams showing typical examples of determination signals detected by photoelectric switches. 1... Compressor, 2... Condenser, 3... Expansion valve,
4...Evaporator, 5...Refrigerant liquid pipe line from the condenser to the expansion valve, 6...Peep window, 7...Transparent glass,
8... Pipe with viewing window, 9... Photoelectric switch light emitting/receiving device, 10... Amplifier unit, 11... Optical fiber, 12... Display panel of equipment operation section or central monitoring room display panel, 13... Power supply and switchboards.

Claims (1)

[Scope of utility model registration request] In a heat pump air conditioner/heater, the refrigerant compressed by a compressor is condensed and liquefied in a condenser, gasified in an evaporator via an expansion valve, and then circulated to the compressor.
A viewing window made of a light-transmitting material is provided on the wall of the refrigerant pipe leading from the condenser to the expansion valve, and a photoelectric switch is placed outside the viewing window so that light passes through the viewing window and into the liquid refrigerant in the pipe. When the photoelectric switch detects the presence of air bubbles in the liquid refrigerant passing through the pipes at a time other than immediately after the heat pump device starts, immediately after unloads, or immediately after the end of the heat pump device during installation and air conditioning operation, refrigerant shortage occurs. A refrigerant shortage determination device for heat pump air conditioners.