JP2008202868A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of a compressor, by securing lubricating oil inside of the compressor, by controlling opening of an orifice device of a refrigerating cycle, by detecting a lubricating oil dilution degree by a simple means, in an air conditioner. <P>SOLUTION: A delivery temperature detecting sensor 11 detecting the delivery temperature and a compressor vessel bottom part temperature detecting sensor 12 detecting the compressor vessel bottom part temperature, are composed of a highly versatile temperature sensor. When a temperature difference between the delivery temperature and the compressor vessel bottom part temperature exceeds a predetermined value, control is performed so as to reduce a refrigerant flow rate by restricting the opening of the orifice device 4, and the lubricating oil inside of the compressor is secured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that controls a throttle by detecting a temperature in the vicinity of a compressor.

  Conventionally, this type of air conditioner throttle device is controlled by a saturation temperature detection sensor for detecting the saturation temperature of the refrigerant in the indoor heat exchanger and an intake temperature detection sensor for detecting the intake temperature of the refrigerant sucked into the compressor. Was controlled by the detected temperature obtained by

  Generally, the refrigerant discharged from the indoor heat exchanger is somewhat dissolved in the lubricating oil of the compressor when returned to the compressor. The dilution indicating the ratio of the refrigerant dissolved in the lubricating oil is defined as (refrigerant weight dissolved in lubricating oil) / (refrigerant weight dissolved in lubricating oil + lubricating oil weight).

When the degree of dilution is higher than a predetermined value, that is, when the refrigerant weight dissolved in the lubricating oil is larger than the predetermined value, the compressor becomes difficult to operate smoothly and may stop. In order to avoid such a situation, for example, as shown in FIG. 5 as an example, a dilution sensor 20 for measuring the dilution indicating the ratio of the refrigerant dissolved in the lubricating oil is provided in the compressor, and the dilution sensor is used for dilution. When the degree exceeds a predetermined value, the flow rate is reduced by a throttling device (see, for example, Patent Document 1).
JP-A-5-005562

  However, the configuration described in Patent Document 1 has a problem that the cost of a dilution sensor with low versatility is high and the productivity in assembly is poor.

  Since the present invention controls the throttle by detecting the temperature in the vicinity of the compressor and secures lubricating oil in the compressor, there is no need to install a special dilution sensor in the compressor, and the air is excellent in productivity at low cost. A harmonic machine can be provided.

  In order to solve the conventional problems, the air conditioner of the present invention detects the discharge temperature at the compressor outlet and the temperature at the bottom of the compressor container, and the temperature difference between these (temperature difference = discharge temperature−compressor container bottom temperature). However, when it exceeds a predetermined value, the flow rate is reduced by the throttle device.

  In this way, by using a versatile temperature detection sensor, it is possible to grasp the state of refrigerant and lubricating oil inside the compressor without using an expensive dilution sensor, and use a throttling device. Can be controlled.

  The air conditioner of the present invention can prevent a shortage of lubricating oil in the compressor, and can provide an air conditioner that is low in cost and excellent in productivity.

The air conditioner of the present invention is provided with a discharge temperature detection sensor for detecting the discharge temperature of the compressor and a compressor container bottom temperature detection sensor for detecting the temperature of the compressor container bottom, and the discharge temperature and the compressor container bottom When the temperature difference is lower than the first predetermined value, the flow rate can be reduced by the throttle device, the dilution degree inside the compressor can be lowered, and the lack of lubricating oil in the compressor can be prevented. Further, when the temperature difference between the discharge temperature and the compressor container bottom is higher than the second predetermined value, the flow rate is increased by the expansion device, so that the temperature rise due to the shortage of refrigerant inside the compressor can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited by embodiment described below.

(Embodiment 1)
FIG. 1 is a block diagram in an embodiment of the present invention.

  In FIG. 1, arrows indicate the flow of refrigerant such as chlorofluorocarbon during cooling operation. The compressor 1 adiabatically compresses the refrigerant in a low-pressure gas state. A discharge temperature detection sensor 11 for detecting the discharge temperature of the compressor is provided at the outlet of the compressor 1, and a compressor container bottom temperature detection sensor 12 for detecting the temperature of the compressor container bottom is provided at the container bottom of the compressor 1. ing.

  The refrigerant in the gaseous state at high pressure and normal temperature discharged from the compressor 1 is sent to the outdoor heat exchanger 3 via the four-way valve 2 that switches between the cooling cycle and the heating cycle. The refrigerant in the gaseous state at high pressure and normal temperature that has entered the outdoor heat exchanger 3 is radiated to the outside by an outdoor blower (not shown) to be in a liquid state at high pressure and normal temperature.

  The liquid refrigerant discharged from the outdoor heat exchanger 3 enters the expansion device 4 where the refrigerant is adiabatically expanded to be in a mixed state of low pressure and low temperature liquid and gas. The refrigerant discharged from the expansion device 4 is sent to the indoor heat exchanger 5.

  While the liquid portion of the refrigerant in a mixed state of the liquid and gas sent to the indoor heat exchanger 5 moves from the inlet to the outlet of the indoor heat exchanger 5, an indoor blower (not shown) Heat is taken as latent heat from the object to be cooled, such as room air, and the object to be cooled is in a gaseous state while being cooled.

  The refrigerant discharged from the indoor heat exchanger 5 is returned to the compressor 1 through the four-way valve 2.

  The indoor heat exchanger 5 is provided with a saturation temperature detection sensor 13 for detecting the saturation temperature of the refrigerant. An intake temperature detection sensor 14 for detecting the intake temperature of the refrigerant sucked into the compressor 1 is provided in the pipe line from the four-way valve 2 to the compressor 1. The saturation temperature detection sensor 13 and the suction temperature detection sensor 14 are for calculating the heating degree of the indoor heat exchanger 5 from these detection temperatures.

  FIG. 2 is a block diagram showing the relationship between the control means and the temperature sensor in the embodiment of the present invention.

  As shown in FIG. 2, the output signals of the discharge temperature detection sensor 11, the compressor container bottom temperature detection sensor 12, the saturation temperature detection sensor 13, and the suction temperature detection sensor 14 are sent to an I / O terminal of a microcomputer 15 as control means. Sent. The control terminal of the diaphragm device 4 is connected to the I / O terminal of the microcomputer 15. Reference numeral 16 denotes a power source that supplies current to the compressor 1 and the microcomputer 15.

  FIG. 3 is a graph showing the relationship between the flow rate change by the expansion device, the discharge temperature, and the compressor container bottom temperature.

  As shown in FIG. 3, when the flow rate is increased by the squeezing device, the discharge temperature and the compressor container bottom temperature decrease, the temperature difference decreases, and when the flow rate is decreased by the squeezing device, the discharge temperature and the compressor container are reduced. The bottom temperature increases and the temperature difference increases.

  FIG. 4 is a graph showing the relationship between the difference between the discharge temperature and the compressor container bottom temperature (discharge temperature−compressor container bottom temperature) and the dilution inside the compressor.

  As shown in FIG. 4, when the difference between the discharge temperature and the compressor container bottom temperature is large, the dilution is low, and when the difference between the discharge temperature and the compressor container bottom temperature is small, the dilution is high.

  That is, the discharge temperature and the compressor container bottom temperature change due to the flow rate change by the expansion device, and the dilution degree can be obtained from the difference between the discharge temperature and the compressor container bottom temperature.

  Next, the operation of the present embodiment having such a configuration will be described.

  Measurement results by the discharge temperature detection sensor 11 and the compressor container bottom temperature detection sensor 12 are sent to the microcomputer 15. The dilution is calculated from the measurement result by the microcomputer 15 and stored in the memory. The memory of the microcomputer 15 stores a heating degree setting value that is a value for setting the heating degree of the indoor heat exchanger 5.

  Further, the measurement results by the saturation temperature detection sensor 13 and the suction temperature detection sensor 14 are sent to the microcomputer 15. From this measurement result, the actual heating degree of the indoor heat exchanger 5 is calculated by the microcomputer 15 and stored in the memory.

  Next, it is determined whether or not the value of the dilution is in a predetermined value range. When the value of the dilution level is within a predetermined value range, a normal heating degree setting value is stored as the heating degree setting value. Next, it is determined whether the heating degree obtained from the measurement results by the saturation temperature detection sensor 13 and the suction temperature detection sensor 14 is too high or too low as compared with the normal heating degree set value stored in the memory. When it is determined that the actual heating degree of the indoor heat exchanger 5 is too high, the opening degree of the valve of the expansion device 4 is controlled to be large. When it is determined that the actual heating degree of the indoor heat exchanger 5 is too low, the opening degree of the valve of the expansion device 4 is controlled to be small. A control signal for adjusting the opening of the valve of the expansion device 4 is sent from the microcomputer 15 to a control terminal (not shown) of the expansion device 4.

  On the other hand, if it is determined that the dilution value exceeds the predetermined range, the normal heating degree setting value stored in the memory is replaced with a heating degree setting value that is higher than normal. Is done. Then, it is determined whether the degree of heating obtained from the measurement results by the saturation temperature detection sensor 13 and the suction temperature detection sensor 14 is too high or too low compared to the heating degree set value set to this high value. Next, the opening degree of the valve of the expansion device 4 is adjusted in the same manner as in the case where the value of the dilution is within the predetermined value range.

  Here, the reason why the heating degree setting value is replaced with a heating degree setting value higher than the normal value when the value of the degree of dilution exceeds the predetermined value range is as follows. That is, a refrigerant in a liquid state among refrigerants in a mixed state discharged from the indoor heat exchanger 5 by operating the indoor heat exchanger 5 at a substantially higher heating degree by increasing the heating degree set value. The ratio of can be reduced. By reducing the ratio of the refrigerant in the liquid state in this way, the dilution can be reduced.

  In the air conditioner configured as described above, the dilution degree can be obtained by using a versatile temperature detection sensor, and the opening degree of the valve of the throttle device can be adjusted by the control means. It is possible to suppress the operation of the air conditioner at a temperature and to prevent the compressor from being stopped due to lack of lubricating oil.

  As described above, the air conditioner according to the present invention can be applied not only to an air conditioner but also to a dehumidifier or a dryer as long as it is equipped with a compressor and constitutes a refrigeration cycle.

Block diagram in an embodiment of the present invention The block diagram which shows the relationship between the control means and temperature sensor in embodiment of this invention Graph showing the relationship between flow rate change by the throttle device, discharge temperature and compressor container bottom temperature A graph showing the relationship between the difference between the discharge temperature and the compressor container bottom temperature and the degree of dilution inside the compressor Block diagram of a conventional air conditioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Throttle device 5 Indoor heat exchanger 11 Discharge temperature detection sensor 12 Compressor container bottom temperature detection sensor 13 Saturation temperature detection sensor 14 Suction temperature detection sensor 15 Microcomputer 16 Power supply 20 Dilution sensor

Claims (1)

An indoor fan circuit comprising an indoor air inlet, an indoor heat exchanger, an indoor fan, and an indoor air outlet, and an outdoor fan circuit comprising an outdoor air inlet, an outdoor heat exchanger, an outdoor fan, and an outdoor air outlet. A refrigeration cycle in which an indoor heat exchanger, an outdoor heat exchanger, a compressor and a throttle device are connected by piping, and a discharge temperature detection sensor for detecting a discharge temperature of the compressor in an air conditioner including a control device, A compressor container bottom temperature detection sensor that detects the temperature of the compressor container bottom is installed, and when the temperature difference between the discharge temperature and the compressor container bottom exceeds a predetermined value, the flow rate is reduced by the expansion device. A featured air conditioner.

Images