JP2011231947A - Outdoor unit and indoor unit, and air-conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect high-pressure-side pressure on a compressor discharge side using a temperature sensor of a heat exchanger.SOLUTION: An outdoor unit including a compressor 1, the outdoor heat exchanger 3, and an outdoor expansion valve 4 includes at least one flow passage for allowing gas refrigerants to flow in the outdoor heat exchanger 3 from two places and to flow out of the outdoor heat exchanger 3 from one place after the refrigerants condensed into two gas and liquid phases are flowed together when the outdoor heat exchanger 3 operates as a condenser, and the temperature sensor 6 for detecting the temperature of the refrigerants is provided at the confluence part.

Description

  The present invention relates to an air conditioner that detects the saturation temperature of a high-pressure refrigerant with a heat exchanger (condenser) and estimates the high-pressure pressure on the compressor discharge side without using a pressure sensor.

  In air conditioners, high pressure on the discharge side of the compressor is detected to ensure compressor reliability by suppressing abnormal rises in high pressure, and to operate the fan and outdoor expansion valve to control the pressure appropriately for the air temperature. To ensure user comfort. However, since the pressure sensor is expensive, there is a problem that the cost of the product increases.

  For example, in the cooling operation, there is a method of estimating the pressure using a temperature detected by a temperature sensor attached to an outdoor heat exchanger arranged on the compressor discharge side instead of the pressure sensor. As a temperature sensor used for pressure estimation, a temperature sensor (hereinafter referred to as an outdoor liquid pipe temperature sensor) attached to the liquid piping of the outdoor heat exchanger used for detecting the frosting state during heating operation is also used. It is common. In the cooling operation, the outdoor heat exchanger becomes a condenser, and the outdoor liquid pipe temperature sensor detects the refrigerant temperature after condensation on the outlet side of the outdoor heat exchanger. Supercooling occurs in temperature conditions that tend to condense and operation with a large amount of refrigerant circulation, and a low temperature is detected with respect to a saturation temperature for a saturation pressure equivalent to the high pressure on the compressor discharge side. Therefore, a low pressure is estimated with respect to the high pressure on the compressor discharge side. At that time, since the actual high pressure is higher than the estimated pressure, the compressor life is reduced due to continued operation in the high pressure state, the feeling of cold air due to excessive cooling capacity, and the air conditioner shut down due to the suppression delay of the high pressure abnormal rise. As a result, the reliability of the product and the comfort of the user are problematic.

  Therefore, in Patent Document 1, not the outlet side of the outdoor heat exchanger but the temperature of the intermediate portion of the heat exchanger in the refrigerant passage in the outdoor heat exchanger is detected to estimate the pressure. Thereby, since the temperature closer to the saturation temperature than the outdoor liquid pipe temperature sensor can be detected, the accuracy of pressure estimation is improved.

Japanese Patent No. 3939292

  In the case of Patent Document 1, if one heat transfer tube distributed in front of the heat exchanger is defined as one distribution, the heat transfer tube length per distribution passing through the heat exchanger is the same for each distribution, and the pressure loss is equivalent. Therefore, it is desirable that the temperature sensor in the middle part of the heat exchanger is at the center of the heat transfer tube. However, when the heat exchanger is increased in order to increase the cooling capacity, the number of heat transfer tubes is increased or the heat transfer tubes are lengthened, so that the heat transfer tubes per distribution passing through the heat exchanger become longer. Pressure loss increases. For this reason, the temperature of the intermediate portion of the heat exchanger is subject to overcooling in temperature conditions where condensation easily occurs and in operation with a large amount of refrigerant circulation, and eventually the same operation as when using an outdoor liquid pipe temperature sensor occurs. .

  An object of the present invention is to accurately detect a high pressure on the compressor discharge side using a temperature sensor of a heat exchanger.

  In order to achieve the above-mentioned object, in the present invention, in an outdoor unit having a compressor, an outdoor heat exchanger, and an outdoor expansion valve, when the outdoor heat exchanger acts as a condenser, At least one flow path that allows gas refrigerant to flow in from two locations, merges the refrigerant condensed in the gas-liquid two-phase and then flows out from one location of the outdoor heat exchanger, and detects the temperature of the refrigerant at the merged portion It is characterized by having a temperature sensor for the purpose.

  Further, in an air conditioner in which a compressor, an outdoor heat exchanger, an outdoor expansion valve, and an indoor heat exchanger are sequentially connected by a refrigerant pipe, when the outdoor heat exchanger acts as a condenser, the outdoor heat exchanger At least one flow path that allows gas refrigerant to flow in from two locations, merges the refrigerant condensed in the gas-liquid two-phase and then flows out from one location of the outdoor heat exchanger, and detects the temperature of the refrigerant at the merged portion It is characterized by having a temperature sensor for the purpose.

  According to the present invention, the high pressure on the compressor discharge side can be detected with high accuracy.

It is a whole block diagram of the air conditioner of Example 1. 1 is a configuration of a heat exchanger of Example 1. It is a ph diagram in the conventional refrigeration cycle. 2 is a ph diagram in the refrigeration cycle of Example 1. FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent.

  The air conditioner of a present Example is demonstrated using FIG.1 and FIG.2.

  First, FIG. 1 is an overall configuration diagram of an air conditioner 50 according to the present embodiment. The outdoor unit 51 includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an outdoor expansion valve 4, an outdoor fan 7, and the like. The indoor unit 52 includes an indoor heat exchanger 5, an indoor fan 8, and the like. The outdoor unit 51 and the indoor unit 52 are connected by a gas connection pipe 53 and a liquid connection pipe 54 to constitute a refrigeration cycle. The control device 16 controls the devices that make up the air conditioner 50.

  The control device 16 controls the operation of the compressor 1. The four-way valve 2 is a valve that switches the flow direction of the refrigerant discharged from the compressor 1 and the flow direction of the refrigerant sucked into the compressor 1. The four-way valve 2 is controlled by the control device 16 so as to form a flow path indicated by a solid line during cooling operation and a flow path indicated by a dotted line during heating operation.

  Next, FIG. 2 shows the outdoor heat exchanger 3 or the indoor heat exchanger 5 of the present embodiment. The outdoor heat exchanger 3 or the indoor heat exchanger 5 includes a large number of plate-like fins 21a and 21b arranged side by side at narrow intervals, U-shaped heat transfer tubes 22a and 22b penetrating these fins, and a U-shaped A bent fin 23 and a trifurcated pipe 24 are connected to the ends of the heat transfer tubes 22a and 22b to form a plate fin type heat exchanger in which a meandering refrigerant pipe is formed. Here, the case where the plate-like fins are arranged in two rows is shown, but the same applies to the case where there are three or more rows. Air is passed through the heat exchanger by the fan, and the refrigerant flowing through the refrigerant pipe takes heat from the air or heat is exchanged by giving heat from the air.

  The refrigeration cycle operation will be described. In the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 reaches the outdoor heat exchanger 3 via the four-way valve 2 and is condensed by the outdoor heat exchanger 3 as indicated by solid arrows. It becomes a liquid refrigerant. This liquid refrigerant reaches the indoor unit 52 through the outdoor expansion valve 4, the liquid blocking valve 12 and the liquid connection pipe 54, and is decompressed in front of the indoor heat exchanger 5 to become a low-pressure gas-liquid mixed refrigerant. The decompressed refrigerant is evaporated in the indoor heat exchanger 5, becomes a gas refrigerant, and returns to the compressor 1 through the gas connection pipe 53. In the case of heating operation, it is indicated by a dotted arrow, and the refrigerant flow direction is reversed. In either case, the heat exchanger into which the refrigerant enters after being discharged from the compressor 1 acts as a condenser, and the outdoor heat exchanger 3 in the cooling operation and the indoor heat exchanger 5 in the heating operation become the condenser.

  FIG. 2 shows the flow of refrigerant when the heat exchanger acts as a condenser arranged after discharge of the compressor. Since the heat exchanger has a large resistance when the refrigerant passes through, the heat exchanger distributes the refrigerant to the heat exchanger and causes the refrigerant to flow into the heat exchanger and out of the heat exchanger. The distribution from the refrigerant flowing into the heat exchanger, passing through the heat exchanger through the refrigerant pipe and flowing out of the heat exchanger is defined as one distribution, and FIG. 2 shows the one distribution (for example, from point a to b point). The refrigerant is caused to flow from two locations of the heat exchanger into the one distribution gas pipe 25 through which the gas refrigerant flows. The refrigerant passes through the refrigerant pipe while exchanging heat with the air, and becomes a gas-liquid two-phase saturated state. A trifurcated pipe 24 is provided in the middle of the refrigerant piping from the inlet to the outlet of the heat exchanger where the refrigerant is in a gas-liquid two-phase saturated state. Here, the refrigerant that has flowed in from two places is merged, and further passes through the refrigerant pipe while exchanging heat, and flows out from one place. By adjusting the pipe size of the liquid pipe 26 through which the refrigerant with a high liquid ratio flows, the amount of refrigerant circulating per distribution can be adjusted, and when the gas-liquid two-phase state with a small pressure loss is reached, the refrigerant is combined. Can be drained.

  Fig.3 (a) shows the ph diagram in the conventional refrigerating cycle. The low enthalpy side of the temperature line is the supercooling region, the high enthalpy side is the superheating region, and the region between them is the saturation region. When condensing in a heat exchanger, the pressure only decreases by the pressure loss due to the piping, but the temperature changes greatly. Conventionally, since the refrigerant temperature in the supercooled state that has greatly decreased with respect to the saturation temperature is measured, an error between the saturation pressure corresponding to the temperature and the actual discharge pressure has increased, and the accuracy of estimation has deteriorated. Further, since there are cases where supercooling is performed or not, it is difficult to stably correct the estimated value.

  FIG.3 (b) shows the ph diagram in the refrigerating cycle of a present Example. In this embodiment, the temperature in the saturation region is detected during condensation in the heat exchanger. Unlike the case of measurement in the supercooling region, the pressure corresponding to the measured temperature (saturation pressure) can be determined in the saturation region. A pressure loss is caused by flowing through the piping, and the saturation pressure has a substantially constant relationship that decreases by the amount of the pressure loss from the discharge pressure, so that the pressure can be accurately estimated.

  That is, according to the present embodiment, the pressure loss can be reduced by dividing the gas refrigerant having a large pressure loss into two portions per distribution and flowing into the heat exchanger. Moreover, the saturated gas-liquid two-phase refrigerant | coolant can be created in the middle of piping by making it flow out, after making the refrigerant flowed in in two places join in the middle. The saturation temperature of the high-pressure refrigerant can be detected by attaching the temperature sensor 6 to a portion that becomes the gas-liquid two-phase refrigerant. It is possible to estimate the high pressure on the discharge side of the compressor by taking this detected temperature into the control device 16 and converting it into a pressure.

  When the measured temperature is higher than the predetermined value, that is, when the pressure value converted from the temperature becomes higher than the predetermined value, the control device 16 issues a command to the compressor 1 to reduce the rotation speed of the compressor 1. In addition to the compressor 1, a command is issued to increase the rotational speed of the outdoor fan 7 (indoor fan 8 during heating operation), and heat exchange is performed in the outdoor heat exchanger 3 (indoor heat exchanger 5 during heating operation). May be promoted. According to these, even when the high pressure of the compressor 1 exceeds a predetermined value, the high pressure can be lowered, so that the compressor 1 is less likely to fail. In the present embodiment, the temperature sensor 6 is provided in the trifurcated pipe 24, but any device may be used as long as the temperature sensor 6 is provided in a portion that becomes a gas-liquid two-phase refrigerant. Since the trifurcated pipe 24 is outside the laminated plate-like fins 21a and 21b, the temperature sensor 6 can be easily attached. Furthermore, the pressure loss up to the merging section is halved due to the two inflows, so even in the temperature conditions where condensation tends to occur and in the operation with a large amount of refrigerant circulation, it is more than the case of one inflow and one outflow from one place per distribution. Since it is difficult to cool and the saturation temperature can be detected reliably, the high pressure can be estimated with high accuracy. It is only necessary to provide at least one flow path for distributing two inflows and one outflow, and in addition, a distribution other than two inflows and one outflow (one inflow and one outflow) may be provided. It is also possible to form a plurality of distributions of two inflows and one outflow. When a plurality of distributions of two inflows and one outflow are formed, only one temperature sensor 6 is required, and there is no problem even if it is determined in consideration of productivity which one of the junctions is attached.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Outdoor expansion valve 5 Indoor heat exchanger 6 Temperature sensor 7 Outdoor fan 8 Indoor fan 11 Gas blocking valve 12 Liquid blocking valve 16 Controller 21a, 21b Plate-shaped fins 22a, 22b Heat pipe 23 Bend pipe 24 Triangular pipe 25 Gas pipe 26 Liquid pipe 50 Air conditioner 51 Outdoor unit 52 Indoor unit 53 Gas connection pipe (refrigerant pipe)
54 Liquid connection piping (refrigerant piping)

Claims (6)

  In an outdoor unit having a compressor, an outdoor heat exchanger, and an outdoor expansion valve, when the outdoor heat exchanger acts as a condenser, gas refrigerant is allowed to flow into the outdoor heat exchanger from two locations, and a gas-liquid two-phase At least one flow path for causing the condensed refrigerant to flow out from one place of the outdoor heat exchanger and then a temperature sensor for detecting the temperature of the refrigerant at the merged portion. Outdoor unit.   In an air conditioner in which a compressor, an outdoor heat exchanger, an outdoor expansion valve, and an indoor heat exchanger are sequentially connected by a refrigerant pipe, when the outdoor heat exchanger acts as a condenser, two locations are provided in the outdoor heat exchanger. In order to detect the temperature of the refrigerant in the merged portion, at least one flow path is provided for allowing the gas refrigerant to flow in, and after the refrigerant condensed in the gas-liquid two phases is merged to flow out from one location of the outdoor heat exchanger. An air conditioner provided with a temperature sensor.   3. The air conditioner according to claim 2, wherein when the temperature detected by the temperature sensor is higher than a predetermined value, the rotational speed of the compressor is decreased.   3. The air conditioner according to claim 2, further comprising an outdoor fan that sends air to the outdoor heat exchanger, and when the temperature detected by the temperature sensor is higher than a predetermined value, the rotational speed of the outdoor fan is increased. Machine.   The air conditioner according to any one of claims 2 to 4, wherein the merging portion is constituted by a trifurcated pipe.   In an indoor unit having an indoor heat exchanger, when the indoor heat exchanger acts as a condenser, gas refrigerant is allowed to flow into the indoor heat exchanger from two locations, and the condensed refrigerant is condensed into a gas-liquid two-phase. An indoor unit comprising: at least one flow path that flows out from one place of the indoor heat exchanger after the heat sensor; and a temperature sensor for detecting the temperature of the refrigerant at the joining portion.

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