KR100572941B1 - Compressor - Google Patents

Abstract

An object of the present invention is to reduce the amount of refrigerant leakage accompanying the change in pressure difference of the compression element of the two-stage compressor to improve the volumetric efficiency and the compressor efficiency.

A sub bearing 19 for storing the electric motor 14 in the sealed container 13 and supporting the rotary compression element and the rotating shaft 2 in which the low pressure compression element 20a and the high pressure compression element 20b are stacked. In the rotary two-stage compressor provided, each of the low pressure compression element 20a and the high pressure compression element 20b is eccentric along the cylindrical cylinders 10a and 10b and the inner walls of the cylinders 10a and 10b. The cylindrical rollers 11a and 11b which rotate to rotate, and the plate-shaped vanes 18 for partitioning the spaces formed on the outer circumferences of the rollers 11a and 11b and the inner walls of the cylinders 10a and 10b. Angle (theta) 1 from the vane 18 of 20a to the position which clearance of the inner wall of cylinder 10a, 10b and the outer periphery of roller 11a, 11b becomes the minimum was set to 150 degrees-210 degrees.

Electric motor, compression element, cylinder, roller, vane, intake pipe, discharge port

Description

Compressor {COMPRESSOR}

1 is a plan view of a low pressure side compression element according to one embodiment of the present invention;

Figure 2 is a plan view of the high pressure side compression element according to an embodiment of the present invention.

3 is a graph showing a relationship between Pm / (Pd × Ps) ^0.5 and a cold-heat average (COP) of a compressor according to one embodiment.

4 is a graph showing the relationship between the crank angle θ and the pressure of the low pressure side compression element according to one embodiment;

5 is a graph showing the relationship between the crank angle θ and the pressure of the high-pressure side compression element according to the embodiment;

6 is a longitudinal sectional view of a two stage compressor according to one embodiment;

7 is a block diagram of a refrigeration cycle using a two-stage compressor according to an embodiment.

8 is a plan view of a compression element by a conventional two stage compressor.

9 is a view showing the flow of the refrigerant gas at the time of closing the discharge valve of the low pressure side compression element by the two-stage compressor according to one embodiment;

10 is a view showing a flow of refrigerant gas when the discharge valve of the low pressure side compression element is opened by the two-stage compressor according to one embodiment;

<Explanation of symbols for the main parts of the drawings>

1: compressor

2: axis of rotation

5, 5a, 5b: eccentric part

10, 10a, 10b: cylinder

11, 11a, 11b: roller

14 electric motor

18: vane

20a, 20b: compression element

25: intake pipe

26 discharge port

27: discharge tube

The present invention relates to a rotary two stage compressor for use in an air conditioner or a refrigerator, and is particularly suitable for a rotary two stage compressor having high volumetric efficiency and compressor efficiency.

Conventionally, it is known to improve the refrigeration cycle efficiency by reducing the pressure ratio (= discharge pressure / intake pressure) of each compression element as a rotary two stage compressor with respect to the refrigeration cycle using a single stage compressor, for example, to patent document 1 It is described.

[Patent Document 1]

Japanese Patent Laid-Open No. 60-128990

In the conventional two stage compressor, as shown in FIG. 8, the shaft center of the rotating shaft 2 and the shaft center of the inner diameter of the cylinder 10 were made to correspond. That is, the clearance (delta) between the outer periphery of the roller 11 and the inner wall of the cylinder 10 was set so that it may become constant irrespective of crank angle (theta) (crank angle (theta) is rotation of the rotating shaft 2). Angle from the vane 18 along the direction to the eccentric direction of the eccentric part 5]. The clearance δ is a value that allows machining precision, assembly accuracy, and load deformation of each component. Therefore, in each compression element, the pressure on the discharge side of the compression chamber 23 increases with an increase in the crank angle θ, and the pressure difference between the discharge side and the intake side also increases, but the clearance δ is independent of the magnitude of the pressure difference. Since the constant is constant, the amount of leakage of refrigerant also increases with an increase in the pressure difference, resulting in a decrease in volumetric efficiency and compressor efficiency.

Moreover, since the phase difference of the compression process of a low pressure side compression element and a high pressure side compression element is 180 degrees, when the discharge valve 28a of the low pressure side compression element 20a is closed as shown in FIG. Due to the intake air of the element 20b, the refrigerant gas is insufficient and the intermediate pressure Pm is lowered.

In addition, when the discharge valve 28a is opened as shown in FIG. 10, the refrigerant gas becomes excessive due to the discharge of the low-pressure side compression element, and the intermediate pressure Pm rises, resulting in a crank angle θ. As a result, the pressure difference between the discharge side and the intake side of each of the compression elements 20a and 20b varies, so that the amount of refrigerant leakage accompanying the pressure difference also fluctuates, making it difficult to control.

An object of the present invention is to reduce the amount of refrigerant leakage in a rotary two-stage compressor, thereby improving volumetric efficiency and compressor efficiency.

In order to achieve the above object, the present invention provides a low pressure through a main shaft supporting the rotating shaft in the lower portion of the motor, and a rotating shaft having two eccentric parts driven by the motor in a sealed container and driven in the upper portion of the motor; A rotary two-stage compressor having a compression element and a high pressure compression element stacked in a stack and a sub-bearing supporting a rotating shaft under the rotary compression element, wherein the low pressure compression element and the high pressure compression element are provided. Each of the elements includes a cylindrical cylinder, a cylindrical roller that rotates eccentrically along the inner wall of the cylinder, and plate-shaped vanes that divide a space formed in the outer circumference of the roller and the inner wall of the cylinder. From the vane of the element to a position where the clearance between the inner wall of the cylinder and the outer circumference of the roller is minimal It is the angle (θ1) with 150 ° to 210 °.

Further, in the above, the angle θ2 from the vane of the compression element for high pressure to the position where the clearance between the inner wall of the cylinder and the outer circumference of the roller is minimum is (θ1 + 20 °) to (θ1 + 60 ° It is preferable to set it to ().

Further, in the above, it is preferable that the clearance between the inner wall of the cylinder of the low pressure compression element and the outer circumference of the roller is set to 5 to 20 m.

Further, in the above, it is preferable that the clearance between the inner wall of the cylinder of the high pressure compression element and the outer circumference of the roller is set to 5 to 20 m.

Further, in the above, the low pressure intaked by the low pressure compression element is Ps, the high pressure discharged by the high pressure compression element is Pd, and the intermediate pressure discharged by the low pressure compression element is Pm, and Pm / It is preferable to make (Pd + Ps) ^0.5 to 0.75 to 1.0.

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

The compressor (1) relates to a refrigerating cycle for a room air conditioner in which the working fluid is a refrigerant (R41OA). The compressor (101) is a sealed container including a bottom portion (21), a lid portion (12), and a body portion (22). The electric motor 14 which consists of the stator 7 and the rotor 8 in the upper part of 13 is provided. The rotating shaft 2 connected to the electric motor 14 is provided with two eccentric parts 5a and 5b, and is journaled to the main bearing 9 and the sub bearing 19. As shown in FIG. The high pressure compression element 20b, the intermediate partition plate 15, and the low pressure compression element 20a are stacked and integrated with each other from the electric motor 14 side with respect to the rotating shaft 2 in order.

Each compression element 20a, 20b is a cylindrical roller 11a fitted to the outer circumference of the main bearing 9 or the sub-bearing 19, the cylindrical cylinders 10a, 10b, and the eccentric portions 5a, 5b. 11b and a flat vane 18 (not shown) connected to the coil spring 24 (not shown) for partitioning the compression chambers 23a and 23b. In each compression element 20a, 20b, the eccentric parts 5a, 5b provided in the rotating shaft 2 drive the rollers 11a, 11b while eccentrically rotating. As shown in Fig. 6, the eccentric part 5a and the eccentric part 5b are 180 degrees out of phase, and the phase difference of the compression process of each compression element 20a, 20b is 180 degrees.

The flow of the refrigerant gas as the working fluid is shown by the arrow in Fig. 6, the refrigerant gas is taken in from the intake pipe 25a into the low pressure compression element 20a at low pressure Ps, and the roller 11a is eccentrically rotated. It is compressed up to the pressure Pm. The discharge valve 28a opens at a predetermined intermediate pressure Pm, and the refrigerant gas is discharged from the discharge port 26a and the discharge pipe 27a.

The refrigerant gas at the intermediate pressure Pm is then taken in from the intake port 25b into the high pressure compression element 20b, and the roller 11b is eccentrically rotated to the high pressure Pd. The discharge valve 28b opens at a predetermined high pressure Pd and is discharged from the discharge pipe 27b through the discharge port 26b and the sealed space 29 in the sealed container 13.

7 shows an example of a refrigeration cycle using a rotary two stage compressor. The refrigerant gas of the high pressure Pd discharged from the compressor 101 is condensed in the condenser 3, and then expanded to the intermediate pressure Pm by the first expansion valve 4 to the gas phase and liquid phase in the gas-liquid separator 6. Are separated. The weather is directed to the injection flow path 17. The liquid refrigerant is further depressurized to the low pressure Ps by the second expansion valve 4 downstream of the gas-liquid separator 6 and then vaporized in the evaporator 16 to gasify. Refrigerant gas of low pressure Ps is taken in from the intake pipe 25a into the low pressure compression element 20a, and the roller 11a fitted to the eccentric part 5a is eccentrically rotated and compressed to intermediate pressure Pm. And it is discharged from the discharge tube 27a. In addition, the roller 11b is mixed with the refrigerant gas of the intermediate pressure Pm induced from the injection flow path 17 to be sucked into the high pressure compression element 20b from the inlet port 25b and fitted to the eccentric portion 5b. Is eccentrically rotated to be compressed up to the high pressure Pb and discharged from the discharge pipe 27b.

Fig. 1 shows the structure of the low pressure compression element 20a, and the crank angle θ1 at which the clearance δ1 of the inner wall of the cylinder 10a and the outer circumference of the roller 11a is minimum is set to 150 ° to 210 °. Good to do. Specifically, the cylinder 10a is eccentric with respect to the rotation axis of the rotation shaft 2 represented by the thick one-dot chain line in the direction in which the crank angle θ is 330 ° to 30 ° with respect to the axis center of the cylinder 10a shown by the thin one-dot chain line. Was set to 180 °, and the clearance (δ1) was set to 5 to 20 µm.

Fig. 2 shows the structure of the high pressure compression element 20b, and the crank angle θ2 at which the clearance δ2 of the inner circumference of the cylinder 10b and the outer circumference of the roller 11b is minimum (θ1 + 20 °) It is good to set it to ((theta) 1 + 60 degrees). Specifically, with respect to the rotation axis of the rotation shaft 2 represented by the thick one-dot chain line, the axis center of the cylinder 10b represented by the thin one-dot chain line has a crank angle θ of (θ1 + 200 °) to (θ1 + 240 °). The cylinder 10b was provided so as to be eccentric in the direction, and θ1 was 180 °, θ2 was (θ1 + 45 °), and δ2 was 5 to 20 μm.

This refrigeration cycle is shown in FIG. 7 as a room air conditioner using refrigerant R41OA as the working fluid. Fig. 3 shows the relationship between the medium pressure Pm and the refrigeration cycle efficiency, here the cooling and heating average COP (−), where the cooling and heating average COP excludes the cooling capacity and heating capacity of the refrigeration cycle from each electric input. It is an arithmetic mean of him.

The cold and cold average (COP) in the figure is the value of the single stage cycle using the single stage compressor, and as shown in the figure, in R41OA, the cold and cold average is higher in the region where the high pressure side pressure ratio (Pd / Pm) is larger than the low pressure side pressure ratio (Pm / Ps). (COP) is the maximum. That is, the cold and cold average COP is maximum at 0.75 to 1.0 centering on the value 0.88 which is relatively low in the intermediate pressure Pm and which is smaller than the rising average Pd × Ps ^0.5 of the high pressure Pd and the low pressure Ps. . Hereinafter, in the present Example, Pm / (Pd x Ps) ^{0.5 was set} to 0.75 to 1.0.

In the case of the two-stage compressor, since the pressure ratio of each of the compression elements 20a and 20b is smaller than that of the single-stage compressor, the start of discharge, that is, the crank angle θ at which the discharge valve 28a is opened, becomes faster. In addition, as shown in Fig. 9, since the intermediate pressure Pm is lowered due to the intake of the high-pressure side compression element 20b, the crank angle θ at which the discharge valve 28a is opened is the average pressure ratio Pm / Ps. Faster than the design point. In addition, the amount of refrigerant leakage is affected by the change in the pressure difference Pm-Ps between the discharge side and the intake side of the compression chamber 23a, and the change in the clearance δ of the cylinders 10a, 10b and the rollers 11a, 11b. . Therefore, the amount of refrigerant leakage is reduced by minimizing the clearance δ at a predetermined crank angle θ1 in consideration of the pressure ratio condition of the high efficiency two stage compressor and the effect of the rapid discharge start due to the intermediate pressure.

In order to improve the efficiency of the two-stage compressor, the high pressure side pressure ratio Pd / Pm is made larger than the low pressure side pressure ratio Pm / Ps as shown in FIG. Therefore, the discharge start angle of the high pressure side compression element 20b is in principle later than the discharge start angle of the low pressure side compression element 20a.

Further, as shown in Fig. 4, the intermediate pressure Pm is changed by the crank angle θ from the influence of the discharge and the intake air of the low pressure side compression element 20a. Therefore, the high pressure side compression element 20b which intakes the refrigerant gas of medium pressure Pm is influenced by the low pressure side compression element 20a, and since the compression process of each compression element 20a, 20b differs 180 degrees, The changes in the intake side pressure (= intermediate pressure Pm) and the discharge side pressure Pd of the side compression element 20b are as shown in FIG. As shown in the figure, the pressure difference Pd-Pm between the discharge side and the intake side increases in the second half of the high pressure side crank angle θ by expansion of the intermediate pressure Pm. Therefore, the amount of refrigerant leakage also increases with increase in the crank angle θ. Therefore, even in the high-pressure side compression element 20b, the clearance δ is not constant and the refrigerant leakage amount is reduced by minimizing the predetermined crank angle θ2. The crank angle θ2 for minimizing the amount of refrigerant leakage is (θ1 + 20 °) to (θ1 + 60 °) larger than the value θ1 of the low pressure side compression element 20a. The amount of refrigerant leakage also depends on the size of the minimum clearance δ2, but the crank angle θ1 which becomes the minimum does not depend on the size of the minimum clearance δ2.

From the above, the compressor of the present invention has determined the positional relationship between the rotating shaft and the cylinder suitable for the compression process of the two-stage compressor in order to reduce the amount of refrigerant leakage caused by the low pressure ratio condition and the intermediate pressure fluctuation of the highly efficient two-stage compressor. Volumetric efficiency and compressor efficiency can be improved. In addition, since only the positional relationship between the cylinder and the rotating shaft is set, an increase in cost due to addition of parts and improvement of machining accuracy can be suppressed.

Claims (5)

A low-pressure compression element and a high-pressure compression element are stacked in a sealed container by storing the electric motor on the upper part, the rotary shaft driven by the electric motor having two eccentric parts, the main bearing supporting the rotary shaft on the lower part of the motor, and the intermediate partition plate. A rotary two-stage compressor having a rotary compression element nested therein and a sub-bearing supporting a rotating shaft under the rotary compression element, Each of the low pressure compression element and the high pressure compression element includes a cylindrical cylinder, a cylindrical roller that rotates eccentrically along the inner wall of the cylinder, and a flat plate that partitions a space formed in the outer circumference of the roller and the cylinder inner wall. With type vanes, A rotary two-stage compressor characterized by setting an angle θ1 from 150 to 210 ° from the vane of the low pressure compression element to a position where the clearance between the inner wall of the cylinder and the outer circumference of the roller is minimum. The angle θ2 from the vane of the compression element for high pressure to a position where the clearance between the inner wall of the cylinder and the outer circumference of the roller is minimum is (θ1 + 20 °) to (θ1 + 60). Rotary type two stage compressor characterized by the above. The rotary two-stage compressor according to claim 1, wherein a clearance between the inner wall of the cylinder of the low pressure compression element and the outer circumference of the roller is set to 5 to 20 m. The rotary two-stage compressor according to claim 1, wherein the clearance between the inner wall of the cylinder of the high pressure compression element and the outer circumference of the roller is set to 5 to 20 m. The method of claim 1, wherein the low pressure drawn from the low pressure compression element is Ps, the high pressure discharged from the high pressure compression element is Pd, and the intermediate pressure discharged from the low pressure compression element is Pm, and Pm / (Pd + Ps) A rotary two-stage compressor, wherein ^{0.5 is set} to 0.75 to 1.0.

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