JP2008240666A - Rotary compressor and heat pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary compressor for improving compression efficiency by reducing a pressure loss in a refrigerant suction pipe for connecting the compressor and an accumulator. <P>SOLUTION: An inner diameter D2 of the refrigerant suction pipe 64 on the outlet side of the accumulator 6, is formed larger than an inner diameter D1 of an inlet side refrigerant return pipe 62 (D2 > D1). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotary compressor used in a refrigeration cycle of a heat pump system such as for an air conditioner, and more particularly to reduction of pressure loss in a connecting pipe between a compressor body and an accumulator.

  In a rotary compressor used in a heat pump system such as an air conditioner, in order to prevent the liquid refrigerant from flowing into the compression section in a transient state, the refrigerant returning from the system refrigeration cycle is gas-liquid for the reliability of the compression section. An accumulator for separation is provided on the side of the compressor body.

  A refrigerant return pipe into which the refrigerant returning from the refrigeration cycle flows into the upper part of the accumulator, and an L-shaped one end extends to the upper part inside the accumulator and the other end extends from the side of the compressor to the lower stage compression part. A refrigerant suction pipe connected to the suction chamber is provided.

  Here, in the accumulator provided in the conventional rotary compressor, there is no example in which the inner diameters of the refrigerant return pipe and the refrigerant suction pipe are considered in detail. For example, as shown in Patent Document 1, the refrigerant return pipe and the refrigerant suction pipe Since the flow rate of the refrigerant flowing through the pipe is the same during the stable continuous operation, the inner diameter is almost the same.

  However, conventionally, the refrigerant suction pipe connecting the rotary compressor and the accumulator has the following problems. That is, in the rotary compressor, since the rate of change of the suction volume during one rotation is not constant, the flow rate fluctuation of the refrigerant occurs in the refrigerant suction pipe.

  On the other hand, in the low-pressure refrigerant pipe and the refrigerant return pipe connecting the accumulator and the refrigeration cycle, the accumulator has a volume 30 to 100 times the volume of the suction chamber of the compression unit, so the flow rate fluctuation is greatly reduced. The Therefore, even if the average flow velocity in the refrigerant return pipe and the refrigerant suction pipe is the same, the pressure loss is approximately proportional to the square of the flow velocity. Therefore, if the flow velocity fluctuation increases, the pressure loss increases, resulting in compression. Inefficiency.

Japanese Unexamined Patent Publication No. Hei 5-19554

  SUMMARY OF THE INVENTION In order to solve the above-described problems, an object of the present invention is to provide a rotary compressor in which the pressure loss of a refrigerant suction pipe connecting a compressor and an accumulator is reduced and the compression efficiency is increased.

  In order to achieve the above-described object, the present invention has several features described below. The invention according to claim 1 is provided with a compressor main body including an electric motor and a rotary type compression portion inside the hermetic shell, and an accumulator on the side of the compressor main body, and an upper part of the accumulator is connected to the refrigeration cycle. In the rotary compressor in which the refrigerant return pipe and the one refrigerant suction pipe connected to the compression section are connected to the lower part, when the inner diameter of the refrigerant return pipe is D1 and the inner diameter of the refrigerant suction pipe is D2, D2 > D1.

  The invention according to claim 2 is characterized in that, in claim 1, the refrigerant suction pipe is arranged so as to be shifted in a direction away from the compressor main body with respect to the central axis of the accumulator.

  According to a third aspect of the present invention, in the first or second aspect, the rotational speed of the compressor is variable.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the rotary compression section includes a low-stage compression section and a high-stage compression section, and discharge from the low-stage compression section. The two-stage compression section is configured to include means for communicating the suction side of the high-stage compression section and the suction side of the high-stage compression section.

  The present invention also includes a heat pump system including the rotary compressor according to any one of claims 1 to 4. That is, the invention according to claim 6 is a heat pump system having a refrigeration cycle including a compressor, a condenser, an expansion mechanism, and an evaporator, and having a low-pressure refrigerant pipe connecting the accumulator and the evaporator of the compressor. The compressor according to any one of claims 1 to 5 is used as the compressor, and the inner diameter of the low-pressure refrigerant pipe is D0, and D2> D0.

  According to the first aspect of the present invention, by increasing the inner diameter D2 of the refrigerant suction pipe on the outlet side from the inner diameter D1 of the refrigerant return pipe on the inlet side of the accumulator (D2> D1), the compressor body and the accumulator can be connected. The pressure loss can be reduced by suppressing the flow velocity fluctuation in the connected refrigerant suction pipe, and the compression efficiency of the compressor can be improved.

  According to the invention described in claim 2, when the inner diameter of the refrigerant suction pipe is increased, it is necessary to increase the bending radius in view of the pressure resistance of the pipe and the workability of the pipe. Therefore, by disposing the refrigerant suction pipe in a direction away from the compressor body with respect to the central axis of the accumulator, even a pipe having a large pipe diameter can be attached to the accumulator without difficulty.

  According to the third aspect of the present invention, when the inverter is operated at a high speed using an inverter system in which the rotation speed of the electric motor is variable, the flow velocity in the refrigerant suction pipe is increased and the pressure loss is increased. Becomes larger.

  According to the invention described in claim 4, the two-stage compression in which the compression phases of the two compression chambers are shifted by 180 ° and these are connected in series to share the low-stage compression section and the high-stage compression section. By using the portion, the balance of the compression torque and the centrifugal force balance of the eccentric portion are excellent, so that the operation can be performed at a higher speed and the flow velocity becomes faster, and thus the effect is further increased.

  The rotary compressor 1 includes a cylindrical sealed container 2 arranged in the vertical direction, and includes an electric motor 4 above the sealed container 2 and a compression unit 3 below.

  The hermetic container 2 includes a cylindrical main shell 21 and a dome-shaped top shell 22 and a bottom shell 23 that close the upper and lower portions of the main shell 21. The top shell 22 and the bottom shell 23 are fixed to the main shell 21 by welding. Has been.

  The top shell 22 is provided with a refrigerant discharge pipe 24 for discharging the refrigerant discharged from the compression unit 3 into the sealed container 2 to the outside of the sealed container 2.

  The stator 41 of the electric motor 4 is shrunk to the main shell 21, and the rotor 42 of the motor 4 is shrunk and fixed to the shaft 7 that mechanically connects the motor 4 and the compression unit 2. An upper balancer 43 and a lower balancer 44 are attached above and below the rotor 42 to balance the centrifugal force of the entire rotating component.

  The compression unit 3 includes a high-stage compression unit 32 on the upper side and a low-stage compression unit 31 on the lower side. The discharge side of the low-stage compression unit 31 and the suction side of the high-stage compression unit 32 are hermetically sealed. By connecting with an external intermediate connecting pipe 26, a two-stage compression section is configured.

  Next, the structure of each compression part 31 and 32 is demonstrated using FIG. FIG. 2 is a cross-sectional view of the lower stage compression unit 31 in FIG. The high-stage compression section 32 has the same configuration except that the phase of the piston differs by 180 °.

  Each compression part 31 and 32 has cylinders 200 and 400 and cylindrical pistons 220 and 420 accommodated inside cylindrical cylinder bores 200a and 400a formed inside the cylinders 200 and 400, respectively. A working space for the refrigerant is formed between the inner walls of 200a and 400a and the outer peripheral surfaces of the pistons 220 and 420.

  The cylinders 200 and 400 are provided with cylinder grooves 200b and 400b from the cylinder bores 200a and 400a toward the outer circumferential direction, and plate-like vanes 230 and 430 are provided in the cylinder grooves 200b and 400b.

  Springs 240 and 440 are provided between the vanes 230 and 430 and the inner wall of the sealed container 2, and the tip of the vanes 230 and 430 is brought into sliding contact with the outer wall of the pistons 220 and 420 by the biasing force of the springs 240 and 440. The space is partitioned into suction chambers V1, V2 and compression chambers C1, C2.

  Next, the whole compressor 1 is demonstrated using FIG. 1 again. A main frame 100 on the high-stage cylinder 200, an intermediate partition plate 300 between the high-stage cylinder 200 and the low-stage cylinder 400, and a subframe 500 under the low-stage cylinder 400; The upper and lower sides of the two working spaces are closed by the main frame 100, the intermediate partition plate 300, and the sub-frame 500, thereby forming a sealed space.

  A high-stage discharge muffler cover 130 and a low-stage discharge muffler cover 510 are provided above the main frame 100 and under the subframe 500, respectively, and a high-stage discharge muffler chamber M2 for reducing pressure pulsation of discharged refrigerant. In addition, a low-stage discharge muffler chamber M1 is formed.

  The high-stage discharge muffler cover 130, the main frame 100, the high-stage cylinder 200, the intermediate partition plate 300, the low-stage cylinder 400, the subframe 500, and the low-stage discharge muffler cover 510 are integrated with bolts (not shown). Further, the outer periphery of the main frame 100 is fixed to the sealed container 2 by spot welding.

  The main frame 100 and the sub frame 500 have bearing portions 110 and 502, and the shaft 7 is rotatably supported by fitting the shaft 7 to the bearing portions 110 and 502.

  The shaft 7 has two crankshafts 72 and 73 eccentric in directions different from each other by 180 °. One crankshaft 72 is fitted to the piston 220 of the high-stage side compression portion 32, and the other crankshaft 73 is The piston 420 of the low-stage compression unit 31 is fitted.

  As the shaft 7 rotates, the pistons 220 and 420 revolve while slidingly contacting the inner walls of the cylinder bores 200a and 400a, and the vanes 230 and 430 reciprocate following the reciprocating movements. And the volume of the compression chambers C1, C2 changes continuously. Thereby, the compression unit 3 repeats the suction and compression of the refrigerant.

  The suction chamber V <b> 1 of the low-stage compression unit 31 is connected to the refrigerant suction pipe 64 via a low-stage suction hole 410 provided in the cylinder 400. The compression chamber C1 of the low-stage compression unit 31 is connected to the intermediate connecting pipe 26 via a low-stage discharge hole 520 and a low-stage discharge muffler chamber M1 provided in the subframe 500.

  More specifically, a check valve 540 is provided in the low-stage side discharge hole 520, and the refrigerant suction pipe 64 is connected to the low-stage side suction hole 410 via the low-stage side suction connection pipe 411, and the intermediate connection pipe 26. Is connected to the low-stage discharge muffler chamber M1 through an intermediate discharge connection pipe 521.

  The suction chamber V <b> 2 of the high stage side compression unit 32 is connected to the intermediate connecting pipe 26 via a high stage side suction hole 210 provided in the cylinder 200. The compression chamber C2 of the high-stage compression section 32 is opened inside the hermetic container 2 through a high-stage discharge hole 120 and a high-stage discharge muffler chamber M2 provided in the main frame 100.

  More specifically, the high-stage discharge hole 120 is provided with a check valve 140, and the intermediate communication pipe 26 is connected to the high-stage suction hole 210 via the intermediate suction connection pipe 211.

  On the side surface of the compressor body 1, an accumulator 6 including an independent sealed container 61 is provided. A refrigerant return pipe 62 connected to the heat pump system side (not shown) is provided at the upper part of the accumulator 6, and an L-shaped one end extends to the upper part inside the accumulator 6 at the lower part of the accumulator 6, and the other end is the compressor 1. The refrigerant suction pipe 64 is connected to the suction chamber V1 of the low-stage compression section 31 from the side surface.

  The refrigerant suction pipe 64 is arranged to be offset toward the anti-compressor main body side with respect to the central axis of the sealed container 61 of the accumulator 6, and the inner diameter D2 of the refrigerant suction pipe 64 is larger than the inner diameter D1 of the refrigerant return pipe 62. (D2> D1: more preferably D2 ≧ 1.2 × D1). The configuration in which the refrigerant suction pipe 64 is offset to the anti-compressor main body side is not limited to the configuration in which the refrigerant suction pipe 64 is offset on the temporary line connecting the center of the compressor main body 1 and the center of the accumulator 6, but from the compressor main body 1 as shown in FIG. Any position where the distance becomes larger is acceptable.

  Next, the flow of the refrigerant having the above configuration will be described with reference to FIGS. 1 and 2. The refrigerant flowing from the system side into the accumulator 6 through the refrigerant return pipe 62 is separated into a liquid refrigerant at the lower part of the accumulator 6 and a gas refrigerant at the upper part of the accumulator 6.

  As the low stage side piston 420 pivots and the volume of the low stage side suction chamber V1 expands, the gas refrigerant in the accumulator 6 passes through the refrigerant suction pipe 64 and the low stage side suction chamber V1 of the compressor body 1. Inhaled.

  After one revolution, the low-stage suction chamber V1 becomes a position that is blocked from the low-stage suction hole 410, and the refrigerant is compressed by switching to the low-stage compression chamber C1 as it is.

  When the compressed refrigerant reaches the pressure in the low-stage discharge muffler chamber M1, which is the outside of the check valve 540 provided in the low-stage discharge hole 520, that is, the intermediate pressure, the check valve 540 opens and the low pressure is reduced. It is discharged into the stage side discharge muffler chamber M1.

  The refrigerant is introduced into the suction chamber V <b> 2 of the high-stage compression section 32 through the intermediate connecting pipe 26 after reducing the pressure flow velocity fluctuation that causes noise in the low-stage discharge muffler chamber M <b> 1.

  The refrigerant guided to the suction chamber V2 of the high-stage compression section 32 is sucked, compressed, and discharged by the high-stage compression section 32 according to the same principle as that of the low-stage compression section 31, and is stored in the high-stage discharge muffler chamber M2. After the pressure flow rate fluctuation is reduced, it is discharged into the closed container 2.

  Further, it is guided to the upper part of the motor 4 through a core notch (not shown) of the stator 41 of the motor 4 and a gap between the core and the winding, and discharged to the system side through the discharge pipe 24.

  In the above flow, since the volume change rate of the low-stage suction chamber V1 is not constant during one rotation, the flow rate fluctuation of the refrigerant occurs in the refrigerant suction pipe 64. On the other hand, in the refrigerant return pipe 62, the accumulator 6 has a volume that is 30 to 100 times the volume of the low-stage suction chamber V1, so that the flow rate fluctuation is greatly reduced.

  Therefore, by making the inner diameter D2 of the refrigerant suction pipe 64 having a large flow rate fluctuation larger than the inner diameter D1 of the refrigerant return pipe 62 (D2> D1), the flow speed in the refrigerant suction pipe 64 becomes slower, and the pressure loss in the suction process is reduced. This improves the compression efficiency of the compressor.

  The above effect will be described with reference to FIGS. FIG. 3 is a graph showing the suction flow velocity in the refrigerant suction pipe 64 with respect to the rotation angle of the piston. The rotation angle was 0 ° at the position where the piston was closest to the vane groove of the cylinder. The suction flow rate is set to 1 when the inner diameter D1 of the refrigerant suction pipe 64 is the same as the inner diameter D2 of the refrigerant return pipe 62 and there is no flow rate fluctuation, that is, the temporal average flow speed is 1. In contrast to (1), the actual flow speeds (3) and (4) vary during one revolution.

  FIG. 4 is a graph showing the suction pressure when the pressure loss is proportional to the square of the suction flow rate with respect to the suction flow rate of FIG. The case where there is no pressure loss is 1.0 MPa. As shown in the graph, the suction pressure fluctuates during one rotation due to fluctuations in the suction flow velocity. When the inner diameter D2 of the refrigerant suction pipe 64 is 1.2 times the case (3) where the inner diameter D2 of the refrigerant suction pipe 64 is the same as the inner diameter D1 of the refrigerant return pipe 62 (3), the pressure fluctuation range is It is reduced to about 1/2.

  FIG. 5 is a graph in which the rotation angle on the horizontal axis in FIG. 4 is converted into the volume of the suction chamber. By making the horizontal axis the volume, the area surrounded by the straight line of suction pressure 1.0 MPa and each curve is expressed as a loss in the suction process, that is, an increase in power consumption of the compressor.

  As shown in the graph, when the refrigerant suction pipe inner diameter D2 is the same as the refrigerant return pipe inner diameter D1 (3), when the refrigerant suction pipe inner diameter D2 is 1.2 times (4), the area indicating the loss is shown. Is reduced to about ½, which corresponds to the area of (1) when there is no flow rate fluctuation when the refrigerant suction pipe inner diameter D2 is the same as the refrigerant return pipe inner diameter D1.

  From the above, it can be seen that the power consumption can be reduced by making the refrigerant suction pipe inner diameter D2 larger than the refrigerant return pipe inner diameter D1, and further by setting D2 ≧ 1.2 × D1, there is no flow rate fluctuation in the refrigerant suction pipe 64. It can be seen that the power consumption can be reduced to the level.

  Further, the refrigerant suction pipe 64 is fixed to the sealed container 61 of the accumulator 6 by being offset from the anti-compressor main body 1, so that the accumulator 6 can be connected to the compressor main body 1 even when the refrigerant suction pipe 64 is thicker than before. It can be arranged closer and can be made compact when mounted on the system.

  In this embodiment, the rotary compressor 1 is exemplified as a compressor including a two-stage compression type compression unit 3 having a low-stage side compression unit 31 and a high-stage side compression unit 32, but the refrigeration cycle is illustrated. Alternatively, a two-stage compression rotary compressor configured to use a gas injection cycle so that the injection refrigerant can flow into an intermediate pressure section between the low-stage compression section 31 and the high-stage compression section 32 may be used.

  Further, the present invention may be applied to a single-stage compression rotary compressor having one compression chamber. In addition, as a compression mechanism of the compression unit 3, if the compressor utilizes the fact that the pistons 220, 420 are swung by the crankshafts 72, 73 and the volumes of the suction chambers V 1, V 2 and the compression chambers C 1, C 2 are changed. The compression mechanism is not limited to the embodiment.

The longitudinal cross-sectional view of the rotary compressor in one Embodiment of this invention. The cross-sectional view of the compression part of the rotary compressor in one Embodiment of this invention. The graph which showed the change of the suction flow velocity with respect to the rotation angle in 1 rotation of the rotary compressor in one Embodiment of this invention. The graph which showed the change of the suction pressure with respect to the rotation angle in 1 rotation of the rotary compressor in one Embodiment of this invention. The graph which showed the change of the suction pressure with respect to the suction volume in 1 rotation of the rotary compressor in one Embodiment of this invention. The perspective view of the state which looked at the rotary compressor in one Embodiment of this invention from the top.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary compressor 2 Sealing shell 3 Compression part (two-stage compression part)
DESCRIPTION OF SYMBOLS 4 Electric motor 41 Stator 42 Rotor 6 Accumulator 62 Refrigerant return pipe 64 Refrigerant suction pipe 7 Shaft 72 High stage side crankshaft 73 Low stage side crankshaft 100 Main frame 110 Main bearing 200 High stage side cylinder 220 High stage side rotary piston 300 Partition plate 400 Low-stage cylinder 420 Low-stage rotary piston 500 Subframe C1 Low-stage compression chamber C2 High-stage compression chamber V1 Low-stage suction chamber V2 High-stage suction chamber

Claims (5)

A compressor main body including an electric motor and a rotary type compression unit inside the hermetic shell, an accumulator is provided on a side of the compressor main body, a refrigerant return pipe connected to a refrigeration cycle at an upper part of the accumulator, and a lower part In the rotary compressor to which one refrigerant suction pipe connected to the compression unit is connected,
A rotary compressor characterized in that D2> D1, where D1 is an inner diameter of the refrigerant return pipe and D2 is an inner diameter of the refrigerant suction pipe.   2. The rotary compressor according to claim 1, wherein the refrigerant suction pipe is arranged so as to be shifted in a direction away from the compressor body with respect to a central axis of the accumulator.   The rotary compressor according to claim 1 or 2, wherein the number of rotations of the compression unit is variable.   The rotary compression unit includes a low-stage compression unit and a high-stage compression unit, and has means for communicating the discharge side of the low-stage compression unit and the suction side of the high-stage compression unit. The rotary compressor according to any one of claims 1 to 3, wherein a two-stage compression unit is configured. In a heat pump system having a refrigeration cycle including a compressor, a condenser, an expansion mechanism and an evaporator, and having a low-pressure refrigerant pipe connecting the accumulator of the compressor and the evaporator,
A heat pump system using the compressor according to any one of claims 1 to 4 as the compressor, wherein D2> D0, where D0 is an inner diameter of the low-pressure refrigerant pipe.

Images