JP2010163922A - Expander-integrated compressor and refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize mechanical loss in a sliding part such as a bearing. <P>SOLUTION: The expander-integrated compressor 200 includes: a compression mechanism 2 having a compression-side bearing 11; an expansion mechanism 3 having an expansion-side bearing 45; and a shaft 5 connecting the compression mechanism 2 to the expansion mechanism 3. The compression mechanism 2 has the same type as the expansion mechanism 3. The ratio (ϕ<SB>e</SB>-D<SB>e</SB>)/(D<SB>e</SB>) of the difference (ϕ<SB>e</SB>-D<SB>e</SB>) between the inside diameter (ϕ<SB>e</SB>) of the expansion-side bearing 45 and the outside diameter (D<SB>e</SB>) of the shaft 5 in the expansion-side bearing 45 to the outside diameter (D<SB>e</SB>) of the shaft 5 in the expansion bearing 45 is larger than the ratio (ϕ<SB>c</SB>-D<SB>c</SB>)/(D<SB>c</SB>) of the difference (ϕ<SB>c</SB>-D<SB>c</SB>) between the inside diameter (ϕ<SB>c</SB>) of the compression-side bearing 11 and the outside diameter (D<SB>c</SB>) of the shaft 5 in the compression-side bearing 11 to the outside diameter (D<SB>c</SB>) of the shaft 5 in the compression-side bearing 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an expander-integrated compressor and a refrigeration cycle apparatus.

A conventional refrigeration cycle apparatus employed in an air conditioner or a water heater uses an expansion valve to expand a refrigerant. In recent years, there has been an attempt to improve the efficiency of a refrigeration cycle by recovering refrigerant expansion energy in the form of power by using a positive displacement expander instead of an expansion valve (see Patent Documents 1 and 2).
JP 2004-44569 A JP 2005-106046 A

  An expander having a sliding portion such as a bearing needs to lubricate the sliding portion with oil. For example, in a refrigeration cycle apparatus using carbon dioxide as a refrigerant, PAG (polyalkylene glycol) can be used as lubricating oil.

  Since oil circulates in the refrigerant circuit, it is essential that the type of oil used in the compressor and the type of oil used in the expander are the same. In the compressor, since the refrigerant is compressed to a high temperature and high pressure state, the temperature of the oil that lubricates the sliding portion of the compressor becomes relatively high. On the other hand, in the expander, the refrigerant expands into a low temperature and low pressure state, and therefore the temperature of the oil that lubricates the sliding portion of the expander is relatively low.

  FIG. 10 is a graph showing changes in the viscosity of oil (PAG) with respect to changes in temperature. As shown in the graph, the change in the viscosity of the oil with respect to the change in temperature is large. Since the change in the viscosity of the oil is large, even if the viscosity of the oil is appropriate in the compressor, the viscosity of the oil may be too high in the expander. If the viscosity of the oil is too large, the mechanical loss at the sliding part such as the bearing becomes large, which is not preferable.

  An object of this invention is to reduce the mechanical loss in sliding parts, such as a bearing.

That is, the present invention
A sealed container;
A compression mechanism having a compression side bearing and housed in the sealed container;
An expansion mechanism having an expansion side bearing and housed in the sealed container;
A shaft that is supported by the compression-side bearing and the expansion-side bearing and that connects the compression mechanism and the expansion mechanism;
The type of the compression mechanism is the same as the type of the expansion mechanism;
The difference (φ _e −D _e ) between the inner diameter (φ _e ) of the expansion side bearing and the outer diameter (D _e ) of the shaft at the expansion side bearing, and the outer diameter of the shaft at the expansion side bearing ( D _e) the ratio of _{(φ e -D e) / (} D e) is the difference between the outer diameter of the shaft of the inner diameter of the compression-side bearing and the (phi _c) in said compression-side bearing (D _c) ( and φ _c -D _c), greater than the ratio _{(φ c -D c) / (} D c) between the outer diameter of said shaft in said compression-side bearing (D _c), provides expander-integrated compressor To do.

In another aspect, the present invention provides:
A sealed container;
A rotary compression mechanism having a compression side cylinder and a compression side piston disposed in the compression side cylinder, and housed in the sealed container;
A rotary expansion mechanism having an expansion side cylinder and an expansion side piston disposed in the expansion side cylinder and housed in the sealed container;
A shaft connecting the rotary compression mechanism and the rotary expansion mechanism;
The difference (H _e −T _e ) between the height (H _e ) of the working chamber in the expansion side cylinder and the thickness (T _e ) of the expansion side piston, and the thickness (T _e ) of the expansion side piston The ratio (H _e −T _e ) / (T _e ) is the difference (H _c −T _c ) between the height (H _c ) of the working chamber in the compression side cylinder and the thickness (T _c ) of the compression side piston. ) And the compression piston thickness (T _c ) ratio (H _c −T _c ) / (T _c ), the expander-integrated compressor is provided.

In yet another aspect, the present invention provides:
A sealed container;
A compression-side cylinder, a compression-side piston disposed in the compression-side cylinder, a compression-side vane that partitions a space between the compression-side cylinder and the compression-side piston into a high-pressure working chamber and a low-pressure working chamber, A compression side vane groove in which a compression side vane is disposed, and a rotary compression mechanism housed in the sealed container;
An expansion side cylinder, an expansion side piston disposed in the expansion side cylinder, an expansion side vane that partitions a space between the expansion side cylinder and the expansion side piston into a high pressure working chamber and a low pressure working chamber, An expansion side vane groove in which an expansion side vane is arranged, and a rotary expansion mechanism housed in the sealed container;
A shaft connecting the rotary compression mechanism and the rotary expansion mechanism;
Ratio (K _e ) of the difference (K _e −W _e ) between the width (K _e ) of the expansion side vane groove and the width (W _e ) of the expansion side vane and the width (W _e ) of the expansion side vane −W _e ) / (W _e ) is the difference (K _c −W _c ) between the width (K _c ) of the compression side vane groove and the width (W _c ) of the compression side vane and the compression side vane Greater than the ratio (K _c −W _c ) / (W _c ) to the width (W _c ) and / or
The ratio of the the difference between the height of the expansion vane groove (h _e) the height of the expansion vane _{(L e) (h e -L} e), the height of the expansion vane as (L _e) (H _e -L _e ) / (L _e ) is the difference (h _c -L _c ) between the height (h _c ) of the compression side vane groove and the height (L _c ) of the compression side vane, Provided is an expander-integrated compressor that is larger than a ratio (h _c -L _c ) / (L _c ) to the height (L _c ) of the compression side vane.

  According to the above-described expander-integrated compressor of the present invention, the clearance ratio in the sliding portion of the expansion mechanism is intentionally larger than the clearance ratio in the sliding portion of the compression mechanism. Can reduce mechanical loss. In other words, the expansion energy of the working fluid (typically refrigerant) can be recovered more efficiently than before by the expansion mechanism. Therefore, it is possible to provide a power recovery type refrigeration cycle apparatus that is more efficient than the prior art.

  The reason why the same type of compression mechanism and expansion mechanism are the subject of the present invention is as follows. At first glance, even if the type of the compression mechanism is different from the type of the expansion mechanism, it seems that the present invention can be applied to a sliding portion having the same function. However, this recognition is not always correct. This is because the difference in model is often linked to the difference in design concept itself. There are many cases where a common fluid design mechanism (for example, a rotary type) has a common design philosophy, and another fluid mechanism (for example, a scroll type) does not necessarily do so. In the same type of fluid mechanism, the present invention that defines the magnitude relationship of the gap ratio is meaningful.

  In addition, a shaft and a bearing are mentioned as a sliding part of a compression mechanism and an expansion mechanism. In the case of a rotary compression mechanism and a rotary expansion mechanism, a cylinder and a piston, a vane and a vane groove are further included.

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

  As shown in FIG. 1, the expander-integrated compressor 200 includes a hermetic container 1, a rotary compression mechanism 2 disposed in the upper part of the hermetic container 1, and a two-stage rotary disposed in the lower part of the hermetic container 1. An expansion mechanism 3, an electric motor 4 disposed between the compression mechanism 2 and the expansion mechanism 3, a shaft 5 connecting the compression mechanism 2, the expansion mechanism 3 and the electric motor 4, and the electric motor 4 and the expansion mechanism 3. An oil pump 6 disposed between them, and a heat insulating member 30 (heat insulating structure) disposed between the expansion mechanism 3 and the oil pump 6 are provided. When the electric motor 4 drives the shaft 5, the compression mechanism 2 operates. The expansion mechanism 3 collects power from the expanding working fluid and applies it to the shaft 5 to assist the drive of the shaft 5 by the electric motor 4. The working fluid is a refrigerant such as carbon dioxide or hydrofluorocarbon.

  The sealed container 1 has an internal space 24 for accommodating each component. The bottom of the sealed container 1 is used as an oil reservoir 25. Oil is used to ensure lubricity and sealing performance at the sliding portions of the compression mechanism 2 and the expansion mechanism 3. The amount of oil in the oil reservoir 25 is adjusted so that the oil level SL (see FIG. 3) is positioned above the oil suction port 62q of the oil pump 6 and below the electric motor 4.

  The oil reservoir 25 includes an upper tank 25a where the oil pump 6 is located and a lower tank 25b where the expansion mechanism 3 is located. The upper tank 25a and the lower tank 25b are separated by a heat insulating member 30. The circumference of the oil pump 6 is filled with the oil in the upper tank 25a, and the circumference of the expansion mechanism 3 is filled with the oil in the lower tank 25b. The oil in the upper tank 25 a is mainly used for the compression mechanism 2, and the oil in the lower tank 25 b is mainly used for the expansion mechanism 3.

  A support frame 75 is disposed between the electric motor 4 and the oil pump 6. The support frame 75 is fixed to the sealed container 1, and the oil pump 6, the heat insulating member 30, and the expansion mechanism 3 are fixed to the sealed container 1 through the support frame 75. A through hole 75 a for returning oil to the oil reservoir 25 is provided in the outer peripheral portion of the support frame 75.

  The oil pump 6 sucks oil from the upper tank 25 a and supplies it to the sliding portion of the compression mechanism 2. After lubricating the compression mechanism 2, the oil that has returned to the upper tank 25 a through the through hole 75 a of the support frame 75 is heated by the compression mechanism 2 and the electric motor 4, and thus has a relatively high temperature. The oil returned to the upper tank 25a is again sucked into the oil pump 6. On the other hand, the oil in the lower tank 25 b is supplied to the sliding portion of the expansion mechanism 3. The oil that has lubricated the sliding portion of the expansion mechanism 3 is returned directly to the lower tank 25b. Since the oil in the lower tank 25b is cooled by the expansion mechanism 3, it is relatively low temperature. An oil pump 6 is disposed between the compression mechanism 2 and the expansion mechanism 3, and the oil pump 6 is used to supply oil to the compression mechanism 2, thereby expanding a high-temperature oil circulation path that lubricates the compression mechanism 2. It can be moved away from the mechanism 3. In other words, it is possible to separate a high-temperature oil circulation path for lubricating the compression mechanism 2 and a low-temperature oil circulation path for lubricating the expansion mechanism 3. Thereby, the heat transfer from the compression mechanism 2 to the expansion mechanism 3 via oil is suppressed.

  By suppressing the heat transfer from the compression mechanism 2 to the expansion mechanism 3, it is possible to prevent a temperature drop of the refrigerant discharged from the compression mechanism 2 and a temperature increase of the refrigerant discharged from the expansion mechanism 3. The coefficient of performance of the system (refrigeration cycle apparatus) using the compressor 200 is improved. The effect of suppressing the heat transfer can be obtained only by the oil pump 6 located between the compression mechanism 2 and the expansion mechanism 3, but the effect can be enhanced by providing the heat insulating member 30.

  Hereinafter, each component will be described in more detail.

  The compression mechanism 2 includes a cylinder 7, a piston 8 disposed in the cylinder 7, a vane 9 that partitions a working chamber 16 formed between the cylinder 7 and the piston 8 into a high pressure working chamber and a low pressure working chamber, A spring 10 is provided. The piston 8 is attached to the eccentric portion 5 a of the shaft 5 and rotates eccentrically in the cylinder 7. A vane 9 is slidably disposed in a vane groove 7 a formed in the cylinder 7. One end (tip) of the vane 9 is in contact with the piston 8. The spring 10 is in contact with the other end (rear end) of the vane 9 and pushes the vane 9 toward the piston 8.

  The compression mechanism 2 further includes a suction pipe 14 that guides the refrigerant to the working chamber 16, a discharge pipe 15 that guides the compressed refrigerant to the outside of the sealed container 1, a lower bearing 11, an upper bearing 12, and a muffler 13. It has. The cylinder 7 is closed by the lower bearing 11 and the upper bearing 12 to form a working chamber 16. The lower bearing 11 and the upper bearing 12 have a suction hole 11p and a discharge hole 12q, respectively. A suction pipe 14 is connected to the suction hole 11p.

  The refrigerant is guided to the working chamber 16 through the suction pipe 14 and the suction hole 11p and compressed. The compressed refrigerant is discharged to the internal space 24 of the sealed container 1 through the discharge hole 12q and the muffler 13. The refrigerant discharged into the internal space 24 is guided to the outside of the sealed container 1 from the discharge pipe 15 after oil mixed in the refrigerant is separated by gravity or centrifugal force.

  The electric motor 4 includes a stator 21 fixed to the hermetic container 1 and a rotor 22 fixed to the shaft 5. Electric power is supplied to the electric motor 4 from a terminal (not shown) arranged at the upper part of the hermetic container 1. The electric motor 4 is cooled by the refrigerant discharged from the compression mechanism 2 and the oil mixed in the refrigerant.

  The shaft 5 includes a first shaft 5s located on the compression mechanism 2 side and a second shaft 5t located on the expansion mechanism 3 side. The first shaft 5s and the second shaft 5t are coupled by a coupler 63 so that the power recovered by the expansion mechanism 3 is transmitted to the compression mechanism 2. However, the first shaft 5s and the second shaft 5t may be directly fitted together. Furthermore, the shaft 5 may be made of a single part.

  Inside the shaft 5, an oil supply passage 29 communicating with the sliding portion of the compression mechanism 2 is formed so as to extend in the axial direction. Oil discharged from the oil pump 6 is fed into the oil supply passage 29. The oil sent to the oil supply passage 29 is supplied to each sliding portion of the compression mechanism 2 without going through the expansion mechanism 3. In this way, the oil traveling toward the compression mechanism 2 is not cooled by the expansion mechanism 3, so that heat transfer from the compression mechanism 2 to the expansion mechanism 3 via the oil can be effectively suppressed.

  The expansion mechanism 3 includes a first cylinder 42, a second cylinder 44 that is thicker than the first cylinder 42, and an intermediate plate 43 that partitions the first cylinder 42 and the second cylinder 44. The first cylinder 42 and the second cylinder 44 are arranged concentrically with each other. 2A and 2B, the expansion mechanism 3 further includes a first piston 46, a first vane 48, a first spring 50, a second piston 47, a second vane 49, and a second spring 51. .

  As shown in FIG. 2A, the first piston 46 is fitted in the eccentric portion 5 c of the shaft 5 and rotates eccentrically in the first cylinder 42. The first vane 48 is slidably disposed in a first vane groove 42 a formed in the first cylinder 42. One end (front end) of the first vane 48 is in contact with the first piston 46. The first spring 50 is in contact with the other end (rear end) of the first vane 48 and pushes the first vane 48 toward the first piston 46.

  As shown in FIG. 2B, the second piston 47 is fitted in the eccentric portion 5 d of the shaft 5 and rotates eccentrically in the second cylinder 44. The second vane 49 is slidably disposed in a second vane groove 44 a formed in the second cylinder 44. One end of the second vane 49 is in contact with the second piston 47. The second spring 51 is in contact with the other end of the second vane 49 and pushes the second vane 49 toward the second piston 47.

  As shown in FIG. 2A, a suction-side working chamber 55a and a discharge-side working chamber 55b are formed inside the first cylinder. The working chamber 55 a and the working chamber 55 b are partitioned by the first piston 46 and the first vane 48. As shown in FIG. 2B, a suction side working chamber 56 a and a discharge side working chamber 56 b are formed inside the second cylinder 44. The working chamber 56 a and the working chamber 56 b are partitioned by the second piston 47 and the second vane 49.

  The total volume of the working chamber 56a and the working chamber 56b in the second cylinder 44 is larger than the total volume of the working chamber 55a and the working chamber 55b in the first cylinder 42. The working chamber 55b and the working chamber 55b and the working chamber 55b are connected to each other through a through hole 43a formed in the intermediate plate 43. The chamber 56a functions as a single expansion chamber.

  As shown in FIG. 1, the expansion mechanism 3 further includes a lower bearing 41, an upper bearing 45, a suction pipe 52, and a discharge pipe 53. The first cylinder 42 is closed by the lower bearing 41 and the middle plate 43, and the second cylinder 44 is closed by the middle plate 43 and the upper bearing 45. Thereby, the working chamber 55 and the working chamber 56 are formed in the first cylinder 42 and the second cylinder 44, respectively.

  Inside the upper bearing 45, a suction path 80 for guiding the refrigerant to the working chamber 55 and a discharge path 81 for guiding the refrigerant discharged from the working chamber 56 to the outside of the expansion mechanism 3 are formed. . The suction path 80 extends to the lower bearing 41 so as to penetrate the second cylinder 44, the intermediate plate 43, and the first cylinder 42, and communicates with the working chamber 55 in the first cylinder 42. The suction pipe 52 is directly inserted into the upper bearing 45 and connected to the suction path 80 so that the refrigerant can be guided from the outside of the sealed container 1 to the working chamber 55 of the first cylinder 42. The discharge pipe 53 is directly inserted into the upper bearing 45 and connected to the discharge path 81 so that the refrigerant can be guided from the working chamber 56 of the second cylinder 44 to the outside of the sealed container 1.

  The refrigerant before expansion flows into the working chamber 55a of the first cylinder 42 through the suction pipe 52 and the suction path 80. The refrigerant flowing into the working chamber 55a of the first cylinder 42 moves to the working chamber 55b according to the rotation of the shaft 5, and rotates the shaft 5 in the expansion chamber formed by the working chamber 55b, the through hole 43a and the working chamber 56a. While expanding. The expanded refrigerant is guided to the outside of the sealed container 1 through the working chamber 56b, the discharge path 81, and the discharge pipe 53.

  The space around the expansion mechanism 3 is filled with oil. Since the rear end of the vane 48 (49) faces the oil reservoir 25, the sliding surface between the vane 48 (49) and the vane groove 42a (44a) can be lubricated. Oil supply to other sliding parts, such as a bearing and a piston, can be performed by an oil supply groove (not shown) formed on the outer peripheral surface of the second shaft 5t so as to extend upward from the lower end of the second shaft 5t. An oil pump may be provided at the lower end of the second shaft 5t, and oil may be supplied to the bearing and the piston with the oil pump. Low temperature oil stored in the lower tank 25 b of the oil reservoir 25 is supplied to each sliding portion of the expansion mechanism 3.

  As shown in FIG. 3, the oil pump 6 is a positive displacement pump configured to pump oil by increasing or decreasing the volume of the working chamber accompanying the rotation of the shaft 5. A hollow relay member 71 that accommodates the coupler 63 is provided adjacent to the oil pump 6. The shaft 5 is passed through the central portion of the oil pump 6 and the relay member 71.

  The oil pump 6 includes a piston 61 attached to an eccentric portion of the shaft 5 (second shaft 5t), and a housing 62 (cylinder) that accommodates the piston 61. A crescent-shaped working chamber 64 is formed between the piston 61 and the housing 62. That is, the oil pump 6 employs a rotary fluid mechanism. The housing 62 includes an oil suction passage 62a that connects the oil reservoir 25 (specifically, the upper tank 25a) and the working chamber 64, an oil discharge passage 62b that connects the working chamber 64 and the oil supply passage 29, and a relay passage 62c. Is formed. The piston 61 rotates eccentrically in the housing 62 as the second shaft 5t rotates. As a result, the volume of the working chamber 64 is increased or decreased, and oil is sucked and discharged. Such a mechanism is advantageous in that the mechanical loss is small because the rotational movement of the second shaft 5t is directly used for the oil-feeding movement without being converted into another movement by a cam mechanism or the like. Further, since it has a relatively simple structure, it has high reliability.

  The oil pump 6 and the relay member 71 are arranged adjacent to each other in the axial direction so that the upper surface of the housing 62 of the oil pump 6 and the lower surface of the relay member 71 are in contact with each other. The relay member 71 is closed by the upper surface of the housing 62. Further, the relay member 71 has a bearing portion 76 that supports the shaft 5 (first shaft 5s). In other words, the relay member 71 also has a function of a bearing that supports the shaft 5. The oil supply passage 29 of the shaft 5 is branched in a section corresponding to the bearing portion 76 so that the bearing portion 76 can be lubricated. Note that the support frame 75 may have a portion corresponding to the bearing portion 76. Furthermore, the support frame 75 and the relay member 71 may be made of a single component.

  A coupler 63 is disposed in the internal space 70 h of the relay member 71. For example, the first shaft 5s and the coupler 63 are synchronously rotated by engaging a groove provided on the outer peripheral surface of the first shaft 5s with a groove provided on the inner peripheral surface of the coupler 63. Are linked together. The second shaft 5t and the coupler 63 can be fixed in the same manner. The coupler 63 rotates in synchronization with the first shaft 5s and the second shaft 5t in the relay member 71. Torque applied to the second shaft 5t by the expansion mechanism 3 is transmitted to the first shaft 5s via the coupler 63.

  The oil supply passage 29 is formed across the first shaft 5s and the second shaft 5t. The connecting portion of the shaft 5, the inlet 29 p of the oil supply passage 29, and the main body portion of the oil pump 6 are arranged in this order from the side close to the compression mechanism 2. The inlet 29p of the oil supply passage 29 is formed on the outer peripheral surface of the second shaft 5t between the upper end portion of the second shaft 5t and the portion where the piston 61 is fitted (eccentric portion). The relay passage 62c is an annular space that surrounds the second shaft 5t in the circumferential direction, and the inlet 29p of the oil supply passage 29 faces the annular space.

  The oil discharged from the oil pump 6 is guided to the oil supply passage 29 through the oil discharge passage 62b and the relay passage 62c. The relay member 71 serves as a housing that accommodates the coupler 63 and serves as a bearing for the shaft 5.

  As shown in FIG. 1, the heat insulating member 30 has a disk shape. The heat insulating member 30 restricts the passage of oil between the upper tank 25a and the lower tank 25b. Due to the action of the heat insulating member 30, the difference between the temperature of the oil stored in the upper tank 25a and the temperature of the oil stored in the lower tank 25b increases. Note that a gap is formed between the outer peripheral surface of the heat insulating member 30 and the inner peripheral surface of the sealed container 1, and oil can travel between the upper tank 25 a and the lower tank 25 b through this gap.

  In the compression mechanism 2, the refrigerant is compressed to a high temperature and high pressure state, so that the temperature of the oil that lubricates the sliding portion of the compression mechanism becomes relatively high. In the expansion mechanism 3, the refrigerant expands to a low temperature and low pressure state, so that the temperature of the oil that lubricates the sliding portion of the expansion mechanism 3 is relatively low. As shown in FIG. 10, the viscosity of the oil varies depending on the temperature. Therefore, even if the oil viscosity is appropriate in the compression mechanism 2, the oil viscosity is too high in the expansion mechanism 3, and the mechanical loss may increase. By designing the gap in the sliding portion of the expansion mechanism 3 to be wider than the dimension considered when designing the compressor, the mechanical loss in the sliding portion can be reduced.

  Typical examples of the “sliding portion” are a bearing and a shaft, a cylinder and a piston, and a vane and a vane groove. Precisely, the piston and the vane slide on the surface of the bearing and the surface of the cylinder that serve as a closing member. Oil can be supplied to these sliding portions of the compression mechanism 2 through the oil supply passage 29 of the shaft 5. Oil can be supplied to these sliding portions of the expansion mechanism 3 through an oil supply groove formed on the outer peripheral surface of the shaft 5 or directly from the oil reservoir 25. Hereinafter, the dimension of the gap in each sliding part will be described.

<< Bearing clearance ratio >>
In a fluid machine such as a positive displacement compressor, it is known to set a bearing clearance ratio defined by a ratio of a bearing clearance dimension to a shaft diameter to about 1/1000 (for example, edited by Japan Society of Tribology) "Tribology Handbook" 1st edition Yokendo March 30, 2001, p111). The dimension of the bearing gap is a design value defined by the difference between the inner diameter of the bearing and the shaft diameter. As far as the compression mechanism 2 is concerned, there is no problem in designing based on this conventional guideline. However, if the expansion mechanism 3 is designed based on this conventional guideline, the shear stress at the bearing increases and the mechanical loss increases. Therefore, the bearing clearance ratio of the expansion mechanism 3 is set larger than the value considered when designing the compressor. Specifically, the mechanical loss in the bearing of the expansion mechanism 3 can be reduced by designing the expansion mechanism 3 so that the bearing clearance ratio of the expansion mechanism 3 is larger than the bearing clearance ratio of the compression mechanism 2.

As shown in FIG. 4, the inner diameter of the lower bearing 11 (compression side bearing) of the compression mechanism 2 is φ _c , the outer diameter of the shaft 5 at the lower bearing 11 is D _c , and the upper bearing 45 (expansion side bearing) of the expansion mechanism 3. the inner diameter of) phi _e, the outside diameter of the shaft 5 in the upper bearing 45 and D _e. In this embodiment, the outer diameter of the first shaft 5s under the bearing 11 is represented by D _c, the outer diameter of the second shaft 5t in the upper bearing 45 is represented by D _e. At this time, the bearing clearance ratio R _c in the lower bearing 11 of the compression mechanism 2 is represented by R _c = (φ _c −D _c ) / D _c . Bearing clearance ratio R _e of the bearing 45 on the expansion mechanism 3 is represented by _{R e = (φ e -D e} ) / D e. By designing the compression mechanism 2 and the expansion mechanism 3 so as to satisfy R _e > R _c , mechanical loss in the upper bearing 45 of the expansion mechanism 3 can be reduced.

The range of the difference between R _e and R _c is not particularly limited, and for example, R _e and R _c may be determined so as to satisfy the relationship of 1.5R _c <R _e <2.5R _c .

Further, the oil viscosity mu _e the oil viscosity mu _c in the compression mechanism 2 in the expansion mechanism 3 may be found bearing clearance ratio R _e in the expansion mechanism 3. Specifically, according to the following formula (1), an appropriate bearing clearance ratio _Re can be set with respect to the oil viscosity.
R _e = (μ _e / μ _c ) × R _c (1)

For example, when the discharge refrigerant temperature of the compression mechanism 2 is 60 to 80 ° C., the ambient temperature of the expansion mechanism 3 is 10 to 30 ° C., and PAG is used as oil, the oil viscosity μ _c is At 80 ° C., 60 ° C., 30 ° C. and 10 ° C., they are 33 mm ² / s, 60 mm ² / s, 135 mm ² / s and 272 mm ² / s, respectively. If the difference between the oil temperature in the oil temperature and the expansion mechanism 3 in the compression mechanism 2 to be 50 ° C., it can set the bearing clearance ratio R _e in the expansion mechanism 3 in the range of 272R _c / 60~135R _c / 33 .

In the present embodiment, the compression mechanism 2 is provided above the electric motor 4, the expansion mechanism 3 is provided below the electric motor 4, and the space around the expansion mechanism 3 is filled with oil. Therefore, a difference is likely to occur between the oil temperature in the compression mechanism 2 and the oil temperature in the expansion mechanism 3. That is, according to the layout of this embodiment can enjoy the effect of reducing mechanical loss due to properly set the bearing clearance ratio R _c and R _e more fully.

In the present embodiment, heat transfer from the compression mechanism 2 to the expansion mechanism 3 is suppressed by the functions of the oil pump 6 and the heat insulating member 30. This is preferable from the viewpoint of preventing the heat transfer from the compression mechanism 2 to the expansion mechanism 3 and improving the efficiency of each mechanism, but is not preferable from the viewpoint of oil viscosity. By properly setting the bearing clearance ratio R _c and R _e, without impairing the effect of suppressing the heat transfer can be eliminated and the oil viscosity problem.

Incidentally, the bearing clearance ratio in the lower bearing 41 of the expansion mechanism 3 may be equal to the bearing gap ratio R _e in the upper bearing 45, may be different. Specifically, the bearing gap ratio in the lower bearing 41 of the expansion mechanism 3 may be larger than the bearing gap ratio in the upper bearing 45 of the expansion mechanism 3. In this embodiment, since the expansion mechanism 3 has a plurality of cylinders, the upper bearing 45 and the lower bearing 41 are separated to some extent in the axial direction. In this case, a certain amount of oil temperature difference also occurs between the upper bearing 45 and the lower bearing 41.

As shown in FIG. 5, the inner diameter of the upper bearing 45 is φ _e1 , the outer diameter of the shaft 5 (specifically, the second shaft 5 t) at the upper bearing 45 is D _e1 , the inner diameter of the lower bearing 41 is φ _e2 , and the lower bearing _Let the outer diameter of the shaft 5 at 41 be _De2 . The bearing clearance ratio R _e1 in the upper bearing 45 is represented by R _e1 = (φ _e1 −D _e1 ) / D _e1 . The bearing clearance ratio R _e2 in the lower bearing 41 is represented by R _e2 = (φ _e2 −D _e2 ) / D _e2 . The compression mechanism 2 and the expansion mechanism 3 satisfy R _e2 > R _e1 and the bearing clearance ratio R _e1 of the upper bearing 45 of the expansion mechanism 3 is larger than the bearing clearance ratio R _c of the lower bearing 11 of the compression mechanism 2. This design can be expected to further reduce mechanical loss.

There is no particular limitation on the scope of the difference between the bearing clearance ratio R _e1 and R _e2, eg 1.1R _e1 <may define R _e1 and R _e2 so as to satisfy the relationship of R _e2 <1.5R _e1.

  Regarding the upper bearing 12 of the compression mechanism 2, there is almost no difference between the oil temperature in the lower bearing 11 and the oil temperature in the upper bearing 12. Therefore, the same bearing clearance ratio (for example, 1/1000) as that of the lower bearing 11 can be adopted for the upper bearing 12.

  In the present embodiment, the suction volume of the compression mechanism 2 is larger than the suction volume of the expansion mechanism 3, and the first shaft 5s is thicker than the second shaft 5t. Therefore, even when the size of the bearing gap in the compression mechanism 2 is equal to the size of the bearing gap in the expansion mechanism 3, the bearing gap ratio in the expansion mechanism 3 is larger than the bearing gap ratio in the compression mechanism 2.

<< Cylinder clearance ratio >>
You may introduce the design concept of a bearing and a shaft into the design of a cylinder and a piston. That is, the design value defined by the difference between the height of the working chamber in the cylinder and the thickness of the piston is defined as the cylinder clearance dimension, and the ratio between the cylinder clearance dimension and the piston thickness is defined as the cylinder clearance ratio. The design concept of the bearing clearance ratio is introduced.

Specifically, as shown in FIG. 6, the height of the working chamber 16 in the cylinder 7 of the compression mechanism 2 is H _c , the thickness of the piston 8 is T _c , and the working chamber in the second cylinder 44 of the expansion mechanism 3. the height of the 56 H _e, the thickness of the second piston 47 and T _e. At this time, the cylinder clearance ratio α _c in the compression mechanism 2 is represented by α _c = (H _c −T _c ) / T _c . The piston clearance ratio α _e in the second cylinder 44 of the expansion mechanism 3 is represented by α _e = (H _e −T _e ) / T _e . By designing the compression mechanism 2 and the expansion mechanism 3 so as to satisfy α _e > α _c , mechanical loss in the second cylinder 44 of the expansion mechanism 3 can be reduced.

The range of the difference between α _e and α _c is not particularly limited. For example, α _e and α _c may be determined so as to satisfy the relationship of 1.5α _c <α _e <2.5α _c .

Note that the cylinder gap ratio in the first cylinder 42 of the expansion mechanism 3 may be equal to the cylinder gap ratio α _e in the second cylinder 44. Further, when the first cylinder 42 is located below the second cylinder 44 as in the present embodiment, the temperature gradient of the oil stored in the oil reservoir 25 is taken into consideration in the first cylinder 42. The cylinder gap ratio may be larger than the cylinder gap ratio in the second cylinder 44. Conversely, when the first cylinder 42 is positioned above the second cylinder 44, the cylinder gap ratio in the first cylinder 42 may be smaller than the cylinder gap ratio in the second cylinder 44.

<< Vane gap ratio >>
You may introduce the design concept of a bearing and a shaft into the design of a vane groove and a vane. That is, the design value defined by the difference between the width of the vane groove and the width of the vane is defined as the dimension of the width direction vane gap, the ratio of the dimension of the width direction vane gap and the width of the vane is defined as the width direction vane gap ratio, The design philosophy of the bearing clearance ratio is introduced into this width direction vane clearance ratio.

Specifically, as shown in FIG. 7A, the width of the vane groove 7a of the compression mechanism 2 is K _c and the width of the vane 9 is W _c, and the second vane groove 44a of the expansion mechanism 3 is shown in FIG. 7B. width K _e, the width of the second vane 49 and W _e of. At this time, the width direction vane clearance ratio β _c in the vane groove 7 a of the compression mechanism 2 is expressed by β _c = (K _c −W _c ) / W _c . The width direction vane gap ratio β _e in the second vane groove 44 a of the expansion mechanism 3 is represented by β _e = (K _e −W _e ) / W _e . By designing the compression mechanism 2 and the expansion mechanism 3 so as to satisfy β _e > β _c , mechanical loss in the second vane groove 44a of the expansion mechanism 3 can be reduced.

Further, the same design concept may be introduced not only in the vane width direction but also in the vane height direction. Specifically, as shown in FIG. 8A, the height of the vane groove 7a of the compression mechanism 2 is h _c , the height of the vane 9 is L _c, and the second vane of the expansion mechanism 3 is shown in FIG. 8B. the height of the groove 44a to h _e, the height of the second vane 49 and the L _e. At this time, the height direction vane clearance ratio γ _c in the vane groove 7 a of the compression mechanism 2 is expressed by γ _c = (h _c −L _c ) / L _c . The height direction vane gap ratio γ _e in the second vane groove 44 a of the expansion mechanism 3 is represented by γ _e = (h _e −L _e ) / L _e . By designing the compression mechanism 2 and the expansion mechanism 3 so as to satisfy γ _e > γ _c , the mechanical loss in the second vane groove 44a of the expansion mechanism 3 can be further reduced.

The range of the difference between β _e and β _c is not particularly limited. For example, β _e and β _c may be determined so as to satisfy the relationship of 1.5β _c <β _e <2.5β _c . The range of the difference between γ _e and γ _c is not particularly limited. For example, γ _e and γ _c may be determined so as to satisfy the relationship of 1.5γ _c <γ _e <2.5γ _c .

Regarding the vane groove and the vane, only one of β _e > β _c and γ _e > γ _c may be satisfied, or both may be satisfied.

The first vane groove 42a the width direction vane gap ratio in the expansion mechanism 3 may be equal to the width direction vane gap ratio beta _e of the second vane groove 44a. Similarly, the height direction vane gap ratio in the first vane groove 42a of the expansion mechanism 3 may be equal to the height direction vane gap ratio beta _e of the second vane groove 44a.

  Further, when the first cylinder 42 is positioned below the second cylinder 44 as in the present embodiment, the first vane groove 42a is taken into account in consideration of the temperature gradient of the oil stored in the oil reservoir 25. The width direction vane gap ratio at may be larger than the width direction vane gap ratio at the second vane groove 44a. Conversely, when the first cylinder 42 is positioned above the second cylinder 44, the width direction vane gap ratio in the first vane groove 42a is smaller than the width direction vane gap ratio in the second vane groove 44a. May be. This is also true for the height direction vane gap ratio.

(Modification)
In this embodiment, the rotary compression mechanism 2 and the rotary expansion mechanism 3 employ a rolling piston type mechanism in which a vane and a piston are made of separate parts. However, the “rotary type” includes a swing piston type in which a vane and a piston are integrated. The rotary mechanism may have only one cylinder, or may have a plurality of cylinders.

  The types of the compression mechanism and the expansion mechanism are not limited to the rotary type, and the compression mechanism and the expansion mechanism may be the same type. For example, other types of fluid mechanisms (typically positive displacement fluid mechanisms) such as a sliding vane type, a scroll type, a reciprocating type, and a screw type can be employed.

  In the present embodiment, the compression mechanism 2 is disposed on the upper side in the vertical direction, and the expansion mechanism 3 is disposed on the lower side in the vertical direction. However, the positional relationship between the compression mechanism 2 and the expansion mechanism 3 may be reversed. That is, the expansion mechanism 3 may be disposed on the upper side in the vertical direction, and the compression mechanism 2 may be disposed on the lower side in the vertical direction. This is because the problem of the difference in oil viscosity between the compression mechanism 2 and the expansion mechanism 3 also occurs in layouts other than this embodiment.

  For the same reason, the axial direction of the shaft may be parallel to the horizontal direction, and the compression mechanism and the expansion mechanism may be located on the left and right in the horizontal direction. A layout in which the axial direction of the shaft is parallel to the horizontal direction is disadvantageous in terms of preventing heat transfer from the compression mechanism to the expansion mechanism, but stability can be expected to be improved by lowering the center of gravity.

(Embodiment of refrigeration cycle apparatus)
FIG. 9 is a configuration diagram of the refrigeration cycle apparatus according to the present embodiment. The refrigeration cycle apparatus 500 includes the expander-integrated compressor 200 described with reference to FIG. 1 and the like, a radiator 402 that cools the refrigerant, and an evaporator 403 that evaporates the refrigerant. By reducing the mechanical loss of the expander-integrated compressor 200, the efficiency of the refrigeration cycle apparatus 500 is improved. The refrigeration cycle apparatus 500 can be applied to products such as an air conditioner, a hot water heater (including one having a heating function), and a dryer.

  Examples of the refrigerator oil include polyol ester, polyvinyl ether, polycarbonate, polyalkylene glycol and the like. When carbon dioxide is used as a refrigerant, polyalkylene glycol is suitable from the viewpoint of lubricity. As described with reference to FIG. 10, the variation range of the viscosity of the polyalkylene glycol is very large. Therefore, the present invention is particularly effective for the combination of carbon dioxide and polyalkylene glycol.

  Further, the present invention is particularly effective for a refrigeration cycle apparatus for a water heater. In a water heater, in order to boil hot water at about 90 ° C., the refrigerant is compressed to a considerably high temperature. In this case, since the difference between the oil temperature in the compression mechanism and the oil temperature in the expansion mechanism tends to increase, the effect of reducing the mechanical loss by applying the present invention increases.

The longitudinal cross-sectional view of the expander integrated compressor concerning embodiment of this invention D1-D1 cross-sectional view of the expander-integrated compressor shown in FIG. D2-D2 cross-sectional view of the expander-integrated compressor shown in FIG. Partial enlarged sectional view of FIG. Schematic showing dimensions of each part (bearing and shaft) of compression mechanism and expansion mechanism Schematic showing the dimensions of each part (bearing and shaft) of the expansion mechanism Schematic showing dimensions of each part (cylinder and piston) of compression mechanism and expansion mechanism Schematic showing the dimensions of each part (vane groove and vane) in the compression mechanism Schematic showing the dimensions of each part (vane groove and vane) in the expansion mechanism Schematic showing the dimensions of each part (vane groove and vane) in the compression mechanism Schematic showing the dimensions of each part (vane groove and vane) in the expansion mechanism Configuration diagram of an example of a refrigeration cycle apparatus Graph showing change in viscosity of PAG with change in temperature

DESCRIPTION OF SYMBOLS 1 Airtight container 2 Compression mechanism 3 Expansion mechanism 4 Electric motor 5 Shaft 5s 1st shaft 5t 2nd shaft 7 Cylinder 7a Vane groove 8 Piston 9 Vane 11 Lower bearing 12 Upper bearing 16 Working chamber 41 Lower bearing 42 First cylinder 44 Second cylinder 42a first vane groove 44a second vane groove 45 upper bearing 46 first piston 47 second piston 48 first vane 49 second vane 55 working chamber 56 working chamber 200 expander-integrated compressor 402 radiator 403 evaporator 500 refrigeration Cycle equipment

Claims (7)

A sealed container;
A compression mechanism having a compression side bearing and housed in the sealed container;
An expansion mechanism having an expansion side bearing and housed in the sealed container;
A shaft that is supported by the compression-side bearing and the expansion-side bearing and that connects the compression mechanism and the expansion mechanism;
The type of the compression mechanism is the same as the type of the expansion mechanism;
The difference (φ _e −D _e ) between the inner diameter (φ _e ) of the expansion side bearing and the outer diameter (D _e ) of the shaft at the expansion side bearing, and the outer diameter of the shaft at the expansion side bearing ( D _e) the ratio of _{(φ e -D e) / (} D e) is the difference between the outer diameter of the shaft of the inner diameter of the compression-side bearing and the (phi _c) in said compression-side bearing (D _c) ( and φ _c -D _c), greater than the ratio _{(φ c -D c) / (} D c) between the outer diameter of said shaft in said compression-side bearing (D _c), the expander-compressor unit. An electric motor disposed between the compression mechanism and the expansion mechanism and driving the shaft;
The expander-integrated compressor according to claim 1, wherein the compression mechanism is provided above the electric motor, and the expansion mechanism is provided below the electric motor. The expansion side bearing includes an upper bearing and a lower bearing,
The difference (φ _e2 −D _e2 ) between the inner diameter (φ _e2 ) of the lower bearing and the outer diameter (D _e2 ) of the shaft at the lower bearing, and the outer diameter (D _e2 ) of the shaft at the lower bearing (Φ _e2 −D _e2 ) / (D _e2 ) is a difference (φ _e1 −D _e1 ) between the inner diameter (φ _e1 ) of the upper bearing and the outer diameter (D _e1 ) of the shaft at the upper bearing. ) And the outer diameter (D _e1 ) of the shaft of the upper bearing is larger than the ratio (φ _e1 −D _e1 ) / (D _e1 ),
The expander-integrated compressor according to claim 2, wherein the ratio (φ _e1 -D _e1 ) / (D _e1 ) is larger than the ratio (φ _c -D _c ) / (D _c ). A sealed container;
A rotary compression mechanism having a compression side cylinder and a compression side piston disposed in the compression side cylinder, and housed in the sealed container;
A rotary expansion mechanism having an expansion side cylinder and an expansion side piston disposed in the expansion side cylinder and housed in the sealed container;
A shaft connecting the rotary compression mechanism and the rotary expansion mechanism;
The difference (H _e −T _e ) between the height (H _e ) of the working chamber in the expansion side cylinder and the thickness (T _e ) of the expansion side piston, and the thickness (T _e ) of the expansion side piston The ratio (H _e −T _e ) / (T _e ) is the difference (H _c −T _c ) between the height (H _c ) of the working chamber in the compression side cylinder and the thickness (T _c ) of the compression side piston. ) And the ratio (H _c −T _c ) / (T _c ) of the compression-side piston thickness (T _c ). A sealed container;
A compression-side cylinder, a compression-side piston disposed in the compression-side cylinder, a compression-side vane that partitions a space between the compression-side cylinder and the compression-side piston into a high-pressure working chamber and a low-pressure working chamber, A compression-side vane groove in which a compression-side vane is disposed, and a rotary compression mechanism housed in the sealed container;
An expansion side cylinder, an expansion side piston disposed in the expansion side cylinder, an expansion side vane that partitions a space between the expansion side cylinder and the expansion side piston into a high pressure working chamber and a low pressure working chamber, An expansion side vane groove in which an expansion side vane is arranged, and a rotary expansion mechanism housed in the sealed container;
A shaft connecting the rotary compression mechanism and the rotary expansion mechanism;
Ratio (K _e ) of the difference (K _e −W _e ) between the width (K _e ) of the expansion side vane groove and the width (W _e ) of the expansion side vane and the width (W _e ) of the expansion side vane −W _e ) / (W _e ) is the difference (K _c −W _c ) between the width (K _c ) of the compression side vane groove and the width (W _c ) of the compression side vane and the compression side vane Greater than the ratio (K _c −W _c ) / (W _c ) to the width (W _c ) and / or
The ratio of the the difference between the height of the expansion vane groove (h _e) the height of the expansion vane _{(L e) (h e -L} e), the height of the expansion vane as (L _e) (H _e -L _e ) / (L _e ) is the difference (h _c -L _c ) between the height (h _c ) of the compression side vane groove and the height (L _c ) of the compression side vane, The expander-integrated compressor, which is larger than a ratio (h _c -L _c ) / (L _c ) to the height (L _c ) of the compression vane. An expander-integrated compressor according to any one of claims 1 to 5;
A radiator for cooling the refrigerant compressed by the compression mechanism of the expander-integrated compressor;
An evaporator for evaporating the refrigerant expanded by the expansion mechanism of the expander-integrated compressor;
A refrigeration cycle apparatus comprising: The refrigerant is carbon dioxide;
The refrigeration cycle apparatus according to claim 6, wherein the lubricating oil is polyalkylene glycol.

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