JP2005106380A - Refrigeration cycle equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freezing cycle device capable of securing control to a cooling medium circuit with high reliability using a pressure sensor of relatively low precision and low cost in simple and low-cost constitution. <P>SOLUTION: In an operation state, with an intake cooling medium saturation operation means 13 set to operate to make cooling medium in an intake tube of a compressor 1 in a saturated state, difference between detected pressure of an intake pressure sensor 11 and saturation pressure determined by a cooling medium saturation pressure operation means 14 based on input of detected temperature by an intake temperature sensor 12 is stored in an intake pressure sensor calibration means 15. Even in a case where a pressure sensor of relatively low precision and low cost is used, this freezing cycle device can calibrate the pressure sensor by itself. Control to the cooling medium circuit of high reliability similar to a case using a pressure sensor of a relatively high precision and high cost can thus be realized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an air conditioner in particular, and particularly relates to provision of an inexpensive pressure detection device.

  As a conventional refrigeration cycle device, avoid using multiple relatively expensive pressure sensors, and devise on the refrigerant circuit so that one pressure sensor can secure the input necessary to control the refrigeration cycle device. (For example, refer to Patent Document 1).

  FIG. 4 shows a pressure detector for a conventional air conditioner described in Patent Document 1. The refrigerant circuit formed by connecting the compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the expansion valve 4, and the indoor heat exchanger 5 in an annular manner reversibly changes the refrigerant circulation direction by the switching operation of the four-way valve 2. The cooling operation and the heating operation can be selected by changing. In an air conditioner equipped with such a refrigerant circuit, when an attempt is made to detect the refrigerant pressure during operation, the refrigerant pressure on the suction side of the compressor 1 (hereinafter referred to as “low pressure”) is heated during cooling operation. During operation, there was a usage pattern in which the refrigerant pressure on the discharge side of the compressor 1 (hereinafter referred to as “high pressure”) was detected.

  In the refrigerant circuit shown in FIG. 4 above, a discharge pressure sensor 21 and a suction pressure sensor 11 are provided in the discharge-side refrigerant flow path and the suction-side refrigerant flow path of the compressor 1, respectively. The high pressure and the low pressure are always detected by 21 and 11, respectively.

  In the refrigerant circuit, during cooling operation, the operation control (rotational speed control) of the compressor 1 is performed based on the low pressure detected by the suction pressure sensor 11 to realize “evaporation pressure constant control”. At the same time, the discharge pressure sensor 21 detects a high pressure, thereby monitoring an abnormal increase in the discharge pressure at a high outside air temperature. Further, during heating operation, the compressor 1 is controlled (rotational speed control) based on the high pressure detected by the discharge pressure sensor 21 to realize “constant condensation pressure control”, and the suction pressure sensor 11 detects a low pressure and monitors an abnormal decrease in the suction pressure at a low outside air temperature.

  FIG. 5 shows a refrigeration cycle apparatus that has been proposed so that the above-described functions can be satisfied by a single pressure sensor. In FIG. 5, the discharge side and the suction side of the compressor 1 are connected via a bypass passage 6, and the bypass passage 6 is connected to an on-off valve 7 and a decompression means 8, and the on-off valve 7 is decompressed. The pressure sensor 9 is disposed between the opening / closing valve 7 and the pressure reducing means 8 while being interposed between the means 8 and the suction side. Accordingly, when the on-off valve 7 is closed, a low pressure pressure on the suction side acts on the portion of the bypass passage 6 located on the suction side with respect to the on-off valve 7 via the decompression means 8, A low pressure is detected by the pressure sensor 9 disposed between the valve 7 and the pressure reducing means 8. On the other hand, when the on-off valve 7 is opened, the refrigerant flows from the discharge side to the suction side through the bypass passage 6. In this case, the passage resistance of the decompression means 8 provided in the bypass passage 6 causes the refrigerant to flow. A high pressure pressure on the discharge side acts on the portion of the pressure sensor 9 provided closer to the discharge side than the decompression means 8, and this is detected by the pressure sensor 9.

As described above, the bypass passage 6 connecting the discharge side and the suction side of the compressor 1 is provided with the on-off valve 7, the decompression means 8, and the pressure sensor 9, respectively, so that the low pressure of the refrigerant circulating in the refrigerant circuit is provided. And the high pressure can be selectively detected, and when the pressure reducing means 8 is constituted by a capillary, for example, it is much cheaper than the on-off valve 7 or the pressure sensor 9. Therefore, compared with the configuration shown in FIG. 4 which includes the two pressure sensors and detects the low pressure and the high pressure, the same function can be realized more simply and at a lower cost.
JP 2002-350004 A

  However, in the conventional configuration, the configuration of the refrigerant circuit is complicated as compared with the configuration including the two pressure sensors in that one pressure sensor is selectively used, and the on-off valve Due to the generation of refrigerant sound during operation or intermittent pressure detection, it has been difficult to cope with sudden pressure fluctuations.

  The present invention solves such a conventional problem, and it is possible to ensure reliable control of a refrigerant circuit by using an inexpensive pressure sensor with relatively low accuracy by a simple and inexpensive configuration. An object of the present invention is to provide a refrigeration cycle apparatus that can be used.

  In order to solve the above-described problems, the present invention provides a refrigerant circuit configured by connecting a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator in an annular shape, the compressor suction pressure detecting means, and the compressor. Suction temperature detecting means, refrigerant saturation pressure calculating means for calculating a saturation pressure from the temperature of the refrigerant sealed in the refrigerant circuit, and suction refrigerant saturation for setting the operation state in which the refrigerant is saturated in the suction pipe of the compressor Deviation between the operating means and the output value from the suction pressure detecting means with respect to the saturation pressure value calculated as the input value of the refrigerant saturation pressure calculating means in the operating state as the output value from the suction temperature detecting means. It has suction pressure calibration means for storing.

  With the above configuration, even when an inexpensive pressure detection means with relatively low accuracy is used, the refrigeration cycle apparatus itself can calibrate the pressure detection means. Equivalently reliable refrigerant circuit control can be realized.

  As described above, the refrigeration cycle apparatus of the present invention is arranged in the refrigerant circuit formed by connecting the compressor, the four-way valve, the condenser, the expansion valve, and the evaporator in an annular shape, and the suction pipe of the compressor. In a suction pressure sensor, a suction temperature sensor disposed in the vicinity of the suction pressure sensor, a refrigerant saturation pressure calculating means for calculating a saturation pressure from the temperature of the refrigerant sealed in the refrigerant circuit, and a suction pipe of the compressor The suction refrigerant saturation operation means for setting the operation state in which the refrigerant is saturated and the detected value of the suction temperature detection means in the operation state are simultaneously detected with respect to the saturation pressure calculated as the input of the refrigerant saturation pressure calculation means. Since the suction pressure sensor calibration means for storing the deviation of the detection value of the suction pressure detection means is provided, according to this configuration, even a relatively inexpensive pressure sensor with low accuracy can be sufficiently cooled for practical use. An effect that the control can be configured refrigerant circuit capable.

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

(Embodiment 1)
FIG. 1 is a control block diagram of a pressure detection device for an air conditioner according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in FIG. In FIG. 1, a suction pressure sensor 11 is disposed in the suction pipe of the compressor 1 and detects the low pressure of the refrigerant circuit. Similar to the suction pressure sensor 11, the suction temperature sensor 12 is disposed in the suction pipe of the compressor 1 and detects the refrigerant temperature in the suction pipe of the compressor. The suction refrigerant saturation operation means 13 is the expansion valve 4.
Of the refrigerant in the indoor heat exchanger 5 is set to be more open than in normal operation, or the rotational speed of an indoor fan (not shown) provided in the indoor heat exchanger 5 is set low. Is set to an operation in which the refrigerant in the suction pipe of the compressor 1 is in a wet state. The refrigerant saturation pressure calculation means 14 calculates the pressure from the temperature of the refrigerant in the saturated state according to the physical properties of the refrigerant sealed in the refrigerant circuit. The suction pressure sensor calibration means 15 receives the temperature detected by the suction temperature sensor 12 at the same time as the suction pressure sensor detection value in the wet operation state set by the suction refrigerant saturation operation means 13 and inputs the temperature detected by the refrigerant saturation pressure calculation means 14. The difference from the calculated saturation pressure is stored.

  FIG. 2 is a diagram showing a relationship between a general pressure and an output voltage of the suction pressure sensor in the present embodiment. In FIG. 2, the suction pressure sensors have variations within a range indicated by oblique lines. For example, the output voltage takes any value within the range of V11 to V12 with respect to the input of the pressure P1. In general pressure sensors, since the absolute value of the detected pressure has an important meaning, accuracy is guaranteed by calibrating using an expensive measuring device at the manufacturing and shipping stage. As a result, a highly accurate pressure sensor is expensive. However, in a general pressure sensor, the relationship between the pressure P and the output voltage V is expressed by the linear expression V = a · P + b, the variation of the slope a value is relatively small, and the intercept b value is often dominant. That is, the characteristic of a general pressure sensor is a characteristic indicated by a straight line having the same inclination in the region indicated by the oblique lines in FIG. In the case of such characteristics, the intercept b can be determined and the pressure sensor can be calibrated if there is one point of data of the pressure P and the output voltage V measured simultaneously.

  According to the first embodiment, the operation state in which the refrigerant in the suction pipe of the compressor becomes wet is forcibly created, the saturation pressure is calculated from the suction temperature at that time, and the pressure sensor for the saturation pressure is calculated. Calibrate the pressure sensor with the deviation of the detected value. According to this method, the suction refrigerant saturation operation means, the refrigerant saturation pressure calculation means, and the suction pressure sensor calibration means can be realized with the same configuration that the air conditioner controls the compressor and the expansion valve during the cooling operation or the heating operation. A highly reliable refrigerant circuit can be configured using an inexpensive low-accuracy pressure sensor without any change on the special refrigerant circuit.

(Embodiment 2)
FIG. 3 is a control block diagram of the pressure detector for the air conditioner according to Embodiment 2 of the present invention. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, a discharge pressure sensor 21 is disposed in the discharge pipe of the compressor 1 and detects the high pressure of the refrigerant circuit. The liquid pipe temperature sensor 22 detects the liquid refrigerant temperature between the outdoor heat exchanger 3 and the expansion valve 4. The liquid pipe refrigerant saturation operation means 23 sets the expansion valve 4 to be more open than during normal operation, or sets the rotational speed of an outdoor fan (not shown) provided in the outdoor heat exchanger 3 to be low. The operation is set so that the refrigerant is prevented from condensing in the outdoor heat exchanger 3 and the refrigerant in the liquid pipe is not supercooled. The discharge pressure sensor calibration means 25 receives as input the temperature detected by the liquid pipe temperature sensor 22 at the same time as the discharge pressure sensor detection value in the operation state in which the liquid pipe set by the liquid pipe refrigerant saturation operation means 23 is not supercooled. The difference from the saturation pressure calculated by the refrigerant saturation pressure calculation means 14 is stored.

  And according to this embodiment, an operation state in which the liquid pipe is not supercooled is forcibly created, the saturation pressure is calculated from the liquid pipe temperature at that time, and the deviation of the detected value of the pressure sensor with respect to the saturation pressure is calculated. Calibrate the pressure sensor. According to this method, a highly reliable refrigerant circuit can be configured by using an inexpensive low-precision pressure sensor without changing the special refrigerant circuit as in the first embodiment.

(Embodiment 3)
Instead of the suction refrigerant saturation operation means 13 in the first embodiment, after the compressor 1 is stopped and the time until the time when the suction temperature and the suction pressure of the compressor reach an equilibrium state has elapsed in advance, The suction pressure sensor calibration means 15 is implemented by storing the difference between the suction pressure sensor detection value and the saturation pressure calculated by the refrigerant saturation pressure calculation means 14 with the temperature detected by the suction temperature sensor 12 at the same time as the input. As in the first embodiment, a highly reliable refrigerant circuit can be configured using an inexpensive low-precision pressure sensor without changing on the special refrigerant circuit.

(Embodiment 4)
Instead of the liquid pipe refrigerant saturation operation means 23 in the second embodiment, after the compressor 1 is stopped and the temperature and pressure of each part of the refrigerant circuit, the liquid pipe temperature or the discharge temperature and the discharge pressure of the compressor are in an equilibrium state, The discharge pressure sensor calibration means 25 stores the difference between the discharge pressure sensor detection value and the saturation pressure calculated by the refrigerant saturation pressure calculation means 14 with the temperature detected by the liquid pipe temperature sensor 22 at the same time as the input. As in the second embodiment, a highly reliable refrigerant circuit can be configured by using an inexpensive low-precision pressure sensor without changing the special refrigerant circuit.

Control block diagram according to Embodiment 1 of the present invention Pressure sensor input / output characteristics diagram of the same embodiment Control block diagram in Embodiment 2 of the present invention Refrigerant circuit diagram of conventional refrigeration cycle equipment Refrigerant circuit diagram proposed as an improvement plan for conventional refrigeration cycle equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Expansion valve 5 Indoor heat exchanger 6 Bypass path 7 On-off valve 8 Pressure reducing means 9 Pressure sensor 11 Suction pressure sensor 12 Suction temperature sensor 13 Suction refrigerant saturation operation means 14 Refrigerant saturation Pressure calculation means 15 Suction pressure sensor calibration means 21 Discharge pressure sensor 22 Liquid pipe temperature sensor 23 Liquid pipe refrigerant saturation operation means 25 Discharge pressure sensor calibration means

Claims (4)

A refrigerant circuit configured by annularly connecting a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator, an intake pressure detecting means of the compressor, an intake temperature detecting means of the compressor, and the refrigerant circuit; Refrigerant saturation pressure calculation means for calculating a saturation pressure from the temperature of the enclosed refrigerant, suction refrigerant saturation operation means for setting the operation state in which the refrigerant is saturated in the suction pipe of the compressor, and the suction in the operation state Suction pressure calibration means for storing a deviation from an output value from the suction pressure detection means with respect to a saturation pressure value calculated as an input value of the refrigerant saturation pressure calculation means as an output value from the temperature detection means. A refrigeration cycle apparatus characterized by. A refrigerant circuit configured by annularly connecting a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator, a discharge pressure detecting means of the compressor, and a liquid refrigerant temperature between the condenser and the expansion valve. Liquid pipe temperature detection means for detecting, liquid pipe refrigerant saturation operation means for setting the operation state in which the refrigerant is saturated in the liquid pipe between the condenser and the expansion valve, and the liquid tube temperature detection in the operation state Discharge pressure calibration means for storing a deviation from an output value of the discharge pressure detection means with respect to a saturation pressure value calculated as an input value of the refrigerant saturation pressure calculation means. Refrigeration cycle equipment. Instead of the suction refrigerant saturation operation means, a timer that presets the time until the temperature and pressure of each part of the refrigerant circuit reaches an equilibrium state after the operation of the refrigerant circuit is stopped, and the suction pressure after the timer has elapsed The refrigeration cycle apparatus according to claim 1, wherein the sensor calibration means is operated. Instead of the liquid pipe refrigerant saturation operation means, a timer that presets the time until the temperature and pressure of each part of the refrigerant circuit reaches an equilibrium state after the operation of the refrigerant circuit is stopped, and the discharge after the timer has elapsed. The refrigeration cycle apparatus according to claim 2, wherein the pressure sensor calibration means is operated.

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