JP5551576B2 - air conditioner - Google Patents

Description

  The present invention relates to an air conditioner provided with an oil separator having a cooling function.

  In general, in an air conditioner, oil for lubrication used in a compressor is discharged in a mixture with a refrigerant. Therefore, an oil separator provided on the discharge side of the compressor is separated from the refrigerant and then returned to the compressor. It is configured to return.

  Conventionally, a configuration of a refrigeration apparatus that cools using liquid refrigerant condensed in an outdoor heat exchanger when returning oil from the oil separator to the compressor has been disclosed (see, for example, Patent Document 1).

JP 2003-130477 A

  However, since there is a concern that the refrigerant used for oil cooling is liquefied, the above-described conventional refrigeration apparatus only discloses a configuration for sucking into an intermediate stage of a two-stage compression compressor, and is used for oil cooling. A configuration for guiding the refrigerant to the compressor suction line is not disclosed.

  Therefore, the present invention presents a configuration that makes it possible to guide the refrigerant used for oil cooling to the compressor suction line while preventing liquefaction of the refrigerant.

  The air conditioner of the present invention for solving the above problems is provided with an oil separator in the discharge line of the compressor, an oil return line from the oil separator to the compressor, and condensed in an outdoor heat exchanger or an indoor heat exchanger. In an air conditioner provided with a receiver for storing liquid refrigerant, and provided with a heat exchanger between the liquid refrigerant of the receiver and return oil to the compressor in the oil return line, the compressor is started and stopped in the oil return line. An on-off valve that opens and closes in conjunction with the heat exchanger, an electric expansion valve that adjusts the amount of liquid refrigerant is provided in the refrigerant line upstream of the heat exchanger, an oil temperature sensor is provided downstream of the on-off valve, and a detection temperature of the oil temperature sensor The electric expansion valve is increased by a predetermined opening when the temperature is equal to or higher than the first predetermined temperature, and the detected temperature of the oil temperature sensor is equal to or lower than the second predetermined temperature lower than the first predetermined temperature The electric expansion valve is decreased by a predetermined opening, a refrigerant pressure sensor is provided in the refrigerant suction line to the compressor, the refrigerant line downstream of the heat exchanger is connected to the refrigerant suction line to the compressor, and the connection A refrigerant temperature sensor is provided downstream of the unit, and when the degree of superheat calculated based on the detection values of the refrigerant temperature sensor and the refrigerant pressure sensor is continuously detected for a predetermined time, the oil temperature sensor The opening degree of the electric expansion valve is decreased by a predetermined opening degree determined based on the degree of superheat instead of an increase / decrease command of the opening degree determined based on the detected temperature.

  Moreover, this invention for solving the said subject WHEREIN: In the said air conditioner, an oil return pipe | tube is inserted from one opening of a cylindrical member, and the one or some bending part is provided in the said cylindrical member, and it inserts it. Take out the oil return pipe from the surface side, reinsert the oil pipe taken out from the other opening of the cylindrical member into the inside, and provide one or more bent parts inside the cylindrical member to provide oil from the reinserting surface The return pipe is taken out again, the oil pipe taken out again is connected to the oil return line to the compressor, an oil return pipe inserted from one opening of the cylindrical member, and an oil return pipe reinserted from the other opening Are separated from each other in the axial direction of the cylindrical member, the oil return pipe inserted from one opening of the cylindrical member is cantilevered by one opening surface, and the oil return pipe reinserted from the other opening is supported by the other opening. Cantilevered on the surface, To Jo member provided inflow and outflow tubes of the refrigerant is obtained by forming the heat exchanger.

  As described above, according to the present invention, the liquid refrigerant in the receiver can be used for oil cooling while preventing liquid back to the compressor.

  According to the second aspect of the present invention, the heat exchange area between the oil and the refrigerant can be ensured while the heat exchanger is made compact, and play against thermal expansion can be secured by the cantilever support of the oil return pipe.

It is a refrigerant circuit figure explaining the flow of the refrigerant at the time of air conditioning of the air conditioner concerning the present invention. It is a refrigerant circuit figure explaining the flow of the refrigerant at the time of heating of the air conditioner concerning the present invention. (A) is the schematic explaining the temperature control of the refrigerant | coolant by a heat exchanger, (b) is the refrigerant circuit figure which simplified the refrigerant circuit around a heat exchanger. It is a partial abbreviation perspective view showing the outline of the whole composition of the heat exchanger used for the air conditioner concerning the present invention. It is the schematic explaining the refrigerant | coolant passage route and oil passage route of the heat exchanger shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 schematically show the refrigerant circuit of the air conditioner 1, and FIG. 3 shows the control of the refrigerant and oil of the air conditioner 1 by the heat exchanger 6.

  The air conditioner 1 is provided with an oil separator 2 in the discharge line 11 of the compressors 1a and 1b, an oil return line 12 from the oil separator 2 to the compressors 1a and 1b, and outdoor heat exchangers 3a and 3b or indoor heat. A receiver 5 for storing the liquid refrigerant condensed in the exchanger 4 is provided, and a heat exchanger 6 for the liquid refrigerant in the receiver 5 and the return oil to the compressors 1a and 1b is provided in the oil return line 12, and is configured. The electric expansion valve EV1 is provided in the refrigerant line 13 upstream of the heat exchanger 6, the on-off valves SV1 and SV2 are provided on the oil return line 12, and the oil temperature sensors TO1 and TO2 are provided downstream of the on-off valves SV1 and SV2. A refrigerant pressure sensor PL1 is provided in the refrigerant suction line 14 to 1a, 1b, a refrigerant line 15 downstream of the heat exchanger 6 is connected to the refrigerant suction line 14 to the compressors 1a, 1b, That it is configured to provide a coolant temperature sensor TS1 downstream of the connecting portion.

  The air conditioner 1 increases the electric expansion valve EV1 by a predetermined opening when the detected temperature of the oil temperature sensors TO1, TO2 is equal to or higher than the first predetermined temperature, and the detected temperature of the oil temperature sensors TO1, TO2 is the first predetermined temperature. When the temperature is lower than the second predetermined temperature lower than the temperature, the electric expansion valve EV1 is decreased by a predetermined opening degree, and the degree of superheat calculated based on the detected values of the refrigerant temperature sensor TS1 and the refrigerant pressure sensor PL1 is equal to or lower than the predetermined value. When the state is detected continuously for a predetermined time, the electric expansion valve EV1 is opened by a predetermined opening determined based on the degree of superheat instead of an opening / closing command determined based on the temperature detected by the oil temperature sensors TO1 and TO2. It is designed to reduce the degree.

  The flow of the refrigerant and oil during heating and cooling of the air conditioner 1 will be described.

  The air conditioner 1 introduces the refrigerant compressed by the compressors 1a and 1b into the oil separator 2 via the discharge line 11 from the compressors 1a and 1b, and separates it into refrigerant and oil.

  Among these, as shown in FIG. 1, in the case of heating operation, the refrigerant dissipates heat in the indoor heat exchanger 4 through the four-way valve 7 and is condensed and liquefied, and then stored in the receiver 5 via the bridge circuit 16. The liquid refrigerant passes through the bridge circuit 16 again and is evaporated and evaporated in the outdoor heat exchangers 3a and 3b by adjusting the opening degree of the electric expansion valve EV2, and then enters the accumulator 9. At this time, the refrigerant calculates the saturated vapor pressure temperature of the refrigerant from the pressure sensor PL1 and the temperature sensor TS2 provided in the refrigerant suction line 14, and is measured from the temperature sensor TS1 before entering the accumulator 9 from the calculated temperature. The opening of the electric expansion valve EV2 is controlled and supplied so that the actual temperature of the refrigerant becomes equal to or higher than a predetermined temperature.

  If the actual degree of superheat of the refrigerant measured from the temperature sensor TS1 before entering the accumulator 9 is still too small, the refrigerant is caused to flow to the sub-evaporator 8 by controlling the opening degree of the electric expansion valve EV3. In FIG. 1, the gas refrigerant is sufficiently heated by the waste heat of the engine (not shown) and then supplied to the accumulator 9. At this time, the temperature of the refrigerant supplied through the sub-evaporator 8 is measured by the temperature sensor TS3. Here, the opening degree control of the electric expansion valve EV3 is performed such that the actual refrigerant temperature measured from the temperature sensor TS3 is equal to or higher than the actual refrigerant temperature measured from the temperature sensor TS1. In this way, while maintaining the opening degree of the electric expansion valve EV2, that is, while ensuring the refrigerant flow rate to the outdoor heat exchangers 3a and 3b and suppressing the pressure loss in the sub-evaporator 8, the degree of superheat of the refrigerant after merging Can be maintained at a predetermined temperature.

  Separately from the paths of the outdoor heat exchangers 3a and 3b and the sub-evaporator 8, the liquid refrigerant in the receiver 5 is supplied from the refrigerant line 13 to the heat exchanger 6 by adjusting the opening of the electric expansion valve EV1. After the refrigerant supplied to the heat exchanger 6 evaporates and cools the oil, it joins the refrigerant line 15 to the refrigerant suction line 14 and then enters the accumulator 9. The connection portion where the refrigerant line 15 merges with the refrigerant suction line 14 is provided on the downstream side of the connection portion where the refrigerant from the sub-evaporator 8 merges with the refrigerant suction line 14. However, the connecting portion where the refrigerant line 15 joins the refrigerant suction line 14 may be provided on the upstream side of the connecting portion where the refrigerant from the sub-evaporator 8 joins the refrigerant suction line 14.

  Thereafter, the refrigerant is sucked again from the accumulator 9 through the refrigerant suction line 14 to the compressors 1a and 1b.

  On the other hand, the oil is cooled by the heat exchanger 6 provided in the oil return line 12, and then returned to the compressors 1a and 1b via the on-off valves SV1 and SV2, capillaries CT1 and CT2, and oil temperature sensors TO1 and TO2. Is done.

  In the case of the cooling operation, as shown in FIG. 2, the refrigerant radiates heat in the outdoor heat exchangers 3 a and 3 b through the four-way valve 7 to condense and is stored in the receiver 5. This liquid refrigerant evaporates and evaporates in the indoor heat exchanger 4 by adjusting the opening degree of the electric expansion valve 41 through the bridge circuit 16 and then enters the accumulator 9. When the degree of superheat of the gas refrigerant that has entered the accumulator 9 is too small, the refrigerant is caused to flow to the sub-evaporator 8 by controlling the opening degree of the electric expansion valve EV3, and the sub-evaporator 8 is sufficient due to waste heat of the engine (not shown). Is supplied to the accumulator 9 after being heated as a gas refrigerant.

  Further, separately from the path of the outdoor heat exchanger 3 and the sub-evaporator 8, the liquid refrigerant in the receiver 5 evaporates and evaporates by cooling the oil in the heat exchanger 6 by adjusting the opening of the electric expansion valve EV1. Enter the accumulator 9.

  Also in this case, after the oil is cooled by the heat exchanger 6 provided in the oil return line 12, it passes through the on-off valves SV1, SV2, capillaries CT1, CT2, and oil temperature sensors TO1, TO2 to the compressors 1a, 1b. Will be returned.

  The compressors 1a and 1b may be operated by only one unit, or may be operated by both units. In the case of operation of only one unit, the on-off valve SV2 is closed, the supply of oil to the compressor 1b is stopped, and only the compressor 1a is operated. In this case, the refrigerant discharged from the compressor 1a is prevented from flowing back to the compressor 1b by the check valve CV1 provided on the downstream side of the compressor 1b. Opening and closing of the on-off valves SV1 and SV2 is interlocked with the start and stop of the compressors 1a and 1b.

  Next, oil temperature control in the air conditioner 1 will be described.

  Degradation of the oil for lubricating the compressors 1a and 1b is promoted in a high temperature and high oxidation environment. Since the mechanical seal portion of the compressors 1a and 1b is a seal surface between heat generated by sliding of the shaft and the outside air, sludge is generated due to deterioration. Therefore, by cooling the oil with a refrigerant, sludge generation is prevented without sacrificing air conditioning. Specifically, as shown in FIG. 3, the flow rate of the refrigerant flowing from the receiver 5 to the heat exchanger 6 is electrically controlled so as not to be in a temperature range (about 75 to 60 ° C.) where sludge is generated in the compressors 1a and 1b. The degree of oil cooling in the heat exchanger 6 is controlled by controlling the expansion valve EV1. At this time, the opening degree control of the electric expansion valve EV1 is performed based on the temperature of the temperature sensors TO1 and TO2 provided in the oil return line 12. If the detected temperature of either one of the temperature sensors TO1 and TO1 (TO1 in the case of single-unit operation) is 53 ° C. or higher, the electric expansion valve EV1 is opened by a predetermined step to increase the cooling efficiency by the heat exchanger 6. If this detected temperature is 48 degrees or less, the electric expansion valve EV1 is closed for a predetermined step to reduce the cooling efficiency by the heat exchanger 6. However, if the degree of superheat of the temperature sensor TS1 provided in the refrigerant suction line 14 is 3.5 ° C. or less, the electric expansion valve EV1 is independent of the control of the electric expansion valve EV1 based on the temperature of the temperature sensors TO1 and TO2. Is closed for a predetermined number of steps.

  Thereby, since the air conditioner 1 can prevent the generation of oil sludge at the mechanical seal portion, the compressor 1a, 1b can be moved to the compressor 1a, 1b without reducing the rotational speed of the compressors 1a, 1b. By cooling the returned oil, the temperature rise of the mechanical seal portion can be suppressed and the generation of sludge can be prevented. In addition, the refrigerant that cools the oil is configured to cool the oil while checking the degree of superheat of the refrigerant by the temperature sensor TS1 provided in the refrigerant suction line 14, so that the refrigerant remains as a liquid refrigerant to the compressors 1a and 1b. So-called liquid back that is inhaled can be prevented.

  In addition, in this Embodiment, although about 75-60 degreeC is illustrated as a temperature range which sludge generate | occur | produces, about this temperature range, it is an illustration to the last, installation of the oil and refrigerant to be used, and the air conditioner 1 Since it differs depending on the environment, it is not particularly limited to such a temperature range. In the present embodiment, the oil is controlled to be within a range of 48 to 53 ° C. by the temperature sensors TO1 and TO2 provided in the oil return line 12, but for this temperature, the sludge is This is a temperature range set in consideration of the generated temperature range (about 75 to 60 ° C.), and is merely an example. Therefore, even if the temperature range where sludge is generated is about 75 to 60 ° C., the oil temperature may have to be controlled in a temperature range different from the range of 48 to 53 ° C. depending on the configuration of the refrigerant circuit. Since it differs depending on the oil and refrigerant to be used, the installation environment of the air conditioner 1, etc., it is not particularly limited to such a temperature range. Furthermore, in the present embodiment, if the degree of superheat of the refrigerant measured by the temperature sensor TS1 is 3.5 ° C. or less, the electric expansion valve EV1 is closed for a predetermined step. However, it is merely an example, and is not particularly limited to such a temperature because it varies depending on the oil and refrigerant to be used, the installation environment of the air conditioner 1, the configuration of the refrigerant circuit, and the like.

  Next, the heat exchanger 6 used in the air conditioner 1 will be described.

  FIG. 4 shows the outline of the overall configuration of the heat exchanger 6, and FIG. 5 shows the outline of the internal configuration of the heat exchanger 6.

  The heat exchanger 6 includes a tubular member 61 and an oil return pipe 62 provided in the tubular member 61.

  The cylindrical member 61 is formed in a long cylindrical shape, and a refrigerant inlet pipe 61a and an outlet pipe 61b are provided in the vicinity of both ends of the outer peripheral surface thereof. Both ends of the cylindrical member 61 are closed by lid members 63a and 63b that cantilever-support the oil return pipe 62, respectively.

  The oil return pipe 62 is constituted by a long thin tube with an internal groove that is accommodated in the cylindrical member 61. The oil return pipe 62 is inserted inside from one end of the cylindrical member 61, folded back to one end side at a position closer to one end than the center of the cylindrical member 61, and taken out from one end of the cylindrical member 61. After that, the tubular member 61 is folded between the outer side of the one end portion and a position closer to the one end than the center several times, and the one end side half of the tubular member 61 is filled with the oil return pipe 62 The portion 62a is configured. Similarly, the oil return pipe 62 is also folded at the other end of the cylindrical member 61 between the outside of the other end of the cylindrical member 61 and a position closer to the other end than the center. A filling portion 62b in which an oil return pipe 62 is filled in the other end side half of 61 is configured. In the oil return pipe 62, a filling portion 62a provided at one end of the tubular member 61 and a filling portion 62b provided at the other end are communicated by a connecting portion 62c provided outside the tubular member 61. Thus, a single oil return path is formed. That is, the oil that has entered from the oil inlet 621 on one end side of the oil return pipe 62 passes through the filling portion 62a, passes through the connecting portion 62c, passes through the filling portion 62b, and is discharged from the oil outlet 622 on the other end side. The The oil inlet 621 and the oil outlet 622 may be reversed.

  In addition, the connecting portion 62c is provided with a bent portion 62d that is bent in an oblique direction without being along the length direction of the tubular member 61, and is connected between the connecting portions 62c by expansion or contraction due to heat. Even if the distance changes, the bent portion 62d can absorb it and cope with it. Further, the filling parts 62a and 62b are also cantilevered by the lid members 63a and 63b, and a gap is formed in the center of the cylindrical member 61. Therefore, the oil return pipe 62 is expanded or contracted by heat. Even if the length is changed, it can cope. Further, the filling portions 62a and 62b are refrigerants whose gaps are maintained by the fret 64 so that the heat exchange efficiency is not lowered due to the contact between the adjacent oil return pipes 62, and the refrigerant flowing in the cylindrical member 61 by the plate 64. The heat exchange efficiency is improved by disturbing the flow of air.

  According to this heat exchanger 6, a heat exchange area between the oil and the refrigerant can be ensured in a compact shape, and play for thermal expansion is secured by cantilevering the oil return pipe 62 at both ends of the cylindrical member 61. can do. Therefore, it can be suitably used for the air conditioner 1 of the present invention.

  In addition, as the shape of the heat exchanger 6, the vertically long heat exchanger 6 is configured by using the cylindrical member 61 formed in a long cylindrical shape. As the shape of the heat exchanger 6, It is not limited to the thing of such a shape in particular, It can form in the appropriate shape according to the empty space of the air conditioner 1.

  The air conditioner according to the present invention is used for various air conditioners having an oil separator.

DESCRIPTION OF SYMBOLS 1 Air conditioner 1a, 1b Compressor 11 Discharge line 12 Oil return line 13 Refrigerant line 14 Refrigerant suction line 15 Refrigerant line 2 Oil separator 3 Outdoor heat exchanger 4 Indoor heat exchanger 5 Receiver 6 Heat exchanger TO1, TO2 Oil temperature sensor TS1 Refrigerant temperature sensor SV1, SV2 On-off valve PL1 Refrigerant pressure sensor EV1 Electric expansion valve

Claims (2)

An oil separator is provided in the discharge line of the compressor, an oil return line from the oil separator to the compressor is provided, a receiver that stores liquid refrigerant condensed in the outdoor heat exchanger or the indoor heat exchanger is provided, and the oil return line In the air conditioner provided with a heat exchanger between the liquid refrigerant of the receiver and the return oil to the compressor,
An opening / closing valve that opens and closes in conjunction with the start / stop of the compressor is provided in the oil return line,
An electric expansion valve for adjusting the amount of liquid refrigerant is provided in the refrigerant line upstream of the heat exchanger,
An oil temperature sensor is provided downstream of the on-off valve,
When the temperature detected by the oil temperature sensor is equal to or higher than a first predetermined temperature, the electric expansion valve is increased by a predetermined opening degree,
When the detected temperature of the oil temperature sensor is equal to or lower than a second predetermined temperature lower than the first predetermined temperature, the electric expansion valve is decreased by a predetermined opening degree,
Provide a refrigerant pressure sensor in the refrigerant suction line to the compressor,
Connecting a refrigerant line downstream of the heat exchanger with a refrigerant suction line to the compressor;
A refrigerant temperature sensor is provided downstream of the connection part,
When the degree of superheat calculated based on the detected values of the refrigerant temperature sensor and the refrigerant pressure sensor is continuously detected for a predetermined time, the degree of opening determined based on the detected temperature of the oil temperature sensor An air conditioner that reduces the opening of the electric expansion valve by a predetermined opening determined based on the degree of superheat instead of an increase / decrease command. In the air conditioner according to claim 1,
An oil return pipe is inserted from one opening of the cylindrical member, one or a plurality of bent portions are provided inside the cylindrical member, the oil return pipe is taken out from the insertion surface side, and the other opening of the cylindrical member is The taken out oil pipe is reinserted into the interior, one or more bent portions are provided inside the cylindrical member, the oil return pipe is taken out again from the reinsertion surface, and the oil pipe taken out again is supplied to the compressor. An oil return pipe inserted from one opening of the cylindrical member and an oil return pipe reinserted from the other opening are separated in the axial direction of the cylindrical member, and connected to the return line. The oil return pipe inserted from the opening is cantilevered on one opening face, and the oil return pipe reinserted from the other opening is cantilevered on the other opening face. A pipe is provided to configure the heat exchanger Air conditioner, characterized in that the.

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