EP2053247A1 - Multistage compressor - Google Patents
Multistage compressor Download PDFInfo
- Publication number
- EP2053247A1 EP2053247A1 EP08722588A EP08722588A EP2053247A1 EP 2053247 A1 EP2053247 A1 EP 2053247A1 EP 08722588 A EP08722588 A EP 08722588A EP 08722588 A EP08722588 A EP 08722588A EP 2053247 A1 EP2053247 A1 EP 2053247A1
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- EP
- European Patent Office
- Prior art keywords
- scroll
- orbiting scroll
- end plate
- compression
- wrap
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
- F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
- F04C18/0215—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2210/00—Fluid
- F04C2210/22—Fluid gaseous, i.e. compressible
Definitions
- the present invention relates to a multistage compressor suitable for a vapor compression refrigerating cycle using carbon dioxide (CO 2 ) as a refrigerant gas (working gas).
- CO 2 carbon dioxide
- the critical temperature of CO 2 is about 31°C, being lower than the critical temperature of CFC, which is the conventional refrigerant. Therefore, when the open-air temperature is high as in summer, the temperature of CO 2 on the radiator side is higher than the critical temperature of CO 2 , so that CO 2 does not condense on the radiator outlet side. Also, the state on the radiator outlet side is determined by the discharge pressure of a compressor and the temperature of CO 2 on the radiator outlet side. Since the temperature of CO 2 on the radiator outlet side is determined by the radiation capacity of the radiator and the open-air temperature (uncontrollable), the temperature of radiator outlet cannot substantially be controlled. Therefore, the state on the radiator outlet side can be controlled by controlling the discharge pressure of the compressor (pressure on the radiator outlet side).
- the pressure on the radiator outlet side must be increased to ensure sufficient cooling capacity (enthalpy difference).
- the operating pressure of the compressor in the vapor compression refrigerating cycle using CO 2 , the operating pressure of the compressor must be increased to three to five times as compared with the conventional refrigerant cycle using CFC.
- a scroll compressor As a compressor used in the vapor compression refrigerating cycle, a scroll compressor is known.
- the scroll compressor includes, in a casing, a fixed scroll having a spiral wrap formed on one side of the end plate thereof, and an orbiting scroll provided, on one side of the end plate thereof, with a spiral wrap that is combined with the wrap of the fixed scroll to form a spiral compression chamber.
- the scroll compressor compresses the introduced working gas in the compression chamber and then discharges the working gas with the orbiting of the orbiting scroll.
- both the end plates of the fixed scroll and the orbiting scroll are smaller than the heights of both the spiral wraps, both the end plates of the fixed scroll and the orbiting scroll are liable to be deflectingly deformed by a load applied at the time of compression.
- the sealing ability of the compression chamber decreases. Therefore, the discharge quantity is decreased by the leakage of working gas from the compression chamber, or the temperature of discharged gas is raised by recompression of leaking gas, so that the performance of the compressor degrades inevitably.
- Patent Document 1 has proposed a technique in which the thicknesses T 1 and T 2 of the end plates of the fixed scroll and the orbiting scroll are made larger than 0.9 times the heights H 1 and H 2 of the spiral wraps of the fixed scroll and the orbiting scroll, respectively. According to the proposal of Patent Document 1, since the thicknesses of the end plates of the fixed scroll and the orbiting scroll are larger than 0.9 times the heights of the spiral wraps of the fixed scroll and the orbiting scroll, respectively, even in the scroll compressor using CO 2 as the working gas, the end plates of the fixed scroll and the orbiting scroll are less liable to be deformed by the load applied at the time of compression, so that the sealing ability of compression chamber is secured.
- Patent Document 1 Japanese Patent Laid-Open No. 2000-352387
- Patent Document 1 contributes to the practical use of the scroll compressor using CO 2 as the working gas.
- the proposal of Patent Document 1 that is, the technique in which the thicknesses T 1 and T 2 of the end plates of the fixed scroll and the orbiting scroll are made larger than 0.9 times the heights H 1 and H 2 of the spiral wraps of the fixed scroll and the orbiting scroll, respectively, is based on the decrease in heights of spiral wraps. Therefore, the application of the proposal of Patent Document 1 is limited to a compressor having a relatively low capacity.
- the present invention has been accomplished in view of the above circumstances, and accordingly an object thereof is to provide a compressor using a gas including a supercritical state, typically CO 2 , as a working gas and capable of having a high capacity.
- a gas including a supercritical state typically CO 2
- the present invention solves the above problems by making the working gas for the multistage compressor including at least one scroll compressor be a gas including a supercritical state, typically CO 2 . That is to say, the present invention is not configured so that the working gas is compressed from a low pressure to a high pressure by singly using a scroll compressor, but, for example, two compression mechanisms are provided to compress the working gas from a low pressure to a medium pressure by one compression mechanism and from the medium pressure to a high pressure by the other compression mechanism. Thereby, the differential pressure in one compression mechanism can be decreased.
- the present invention provides a multistage compressor including an enclosed housing; a plurality of compression mechanisms provided in the enclosed housing; and a motor for driving the plurality of compression mechanisms, wherein at least one of the plurality of compression mechanisms is a scroll compression mechanism, and a gas including a supercritical state is used as a working gas, characterized in that the scroll compression mechanism includes a fixed scroll having a spiral wrap formed on one side of an end plate thereof, and an orbiting scroll provided, on one side of an end plate thereof, with a spiral wrap that is combined with the spiral wrap of the fixed scroll to form a compression chamber, and the introduced working gas is compressed in the compression chamber as the orbiting scroll orbits; and taking the thickness of the end plate of the orbiting scroll as Worb and the height of the spiral wrap of the orbiting scroll as L, a condition of L ⁇ Worb is satisfied.
- a condition of Wfix ⁇ L ⁇ Worb is preferably satisfied. This condition contributes to the prevention of deformation of the end plate of the fixed scroll.
- a condition of 2 ⁇ L/Tr ⁇ 7 is preferably satisfied. Thereby, the strength of the spiral wrap of the orbiting scroll is secured while securing the displacement.
- the multistage compressor in accordance with the present invention taking the outside diameter of the end plate of the orbiting scroll as Dout, the outside diameter of the spiral wrap of the orbiting scroll as Dwrap, and the inside diameter of a support part on the back surface of the orbiting scroll as Db, conditions of Dwrap/Dout ⁇ 0.7 and Db ⁇ Dwrap are preferably satisfied.
- Dwrap/Dout ⁇ 0.7 and Db ⁇ Dwrap are preferably satisfied.
- the multistage compressor in which at least one of the plurality of compression mechanisms is a scroll compression mechanism, and CO 2 is used as the working gas, taking the thickness of the end plate of the orbiting scroll of the scroll compression mechanism as Worb and the height of the spiral wrap of the orbiting scroll thereof as L, the condition of L ⁇ Worb is satisfied.
- the height of the spiral wrap of the orbiting scroll (fixed scroll) can be increased, so that the capacity of the compressor using CO 2 as the working gas can be increased.
- 100 ... enclosed housing, 101 ... rolling piston compression mechanism, 102 ... scroll compression mechanism, 103 ... motor, 111 ... fixed scroll, 112 ... end plate, 113 ... wrap, 116 ... orbiting scroll, 117 ... end plate, 118 ... wrap, SA ... enclosed space
- Figure 1 is a longitudinal sectional view showing a configuration of a multistage compressor of this embodiment.
- a rolling piston compression mechanism 101 and a scroll compression mechanism 102 are disposed in an enclosed housing 100. Between the rolling piston compression mechanism 101 and the scroll compression mechanism 102, a motor 103 (electric motor) for driving the two compression mechanisms 101 and 102 is disposed.
- the multistage compressor is explained in more detail below.
- the scroll compression mechanism 102 In the upper part of the cylindrical enclosed housing 100 extending along the up and down direction, the scroll compression mechanism 102 is accommodated. Under the scroll compression mechanism 102, the motor 103 (electric motor) is accommodated. Also, between the scroll compression mechanism 102 and the motor 103, a rotating shaft 110 is disposed.
- the motor 103 includes a stator 103a that is press fitted in and supported by the inner peripheral part of the enclosed housing 100 and a rotor 103b arranged on the inside of the stator 103a.
- the rotor 103b is coaxially fixed on the rotating shaft 110, and the rotation of the rotor 103b is output from the rotating shaft 110.
- the scroll compression mechanism 102 includes a fixed scroll 111 the whole of which is made of an iron-based material such as cast iron or carbon steel, and an orbiting scroll 116 made of an iron-based material, which meshes with the fixed scroll 111.
- the fixed scroll 111 includes an end plate 112, a spiral wrap 113 formed on the inner surface of the end plate 112 facing to the orbiting scroll 116, and a peripheral wall 114 surrounding the wrap 113. Also, in the central part of the end plate 112, a discharge port 115 is provided.
- the orbiting scroll 116 includes an end plate 117 and a spiral wrap 118 formed on the inner surface of the end plate 117 facing to the fixed scroll 111.
- a cylindrical boss part 119 is projectingly provided in the central part of the back surface of the end plate 117 facing to the inner surface.
- the fixed scroll 111 and the orbiting scroll 116 are assembled so that the wrap 113 and the wrap 118 are meshed with each other being shifted through 180 degrees (a predetermined angle).
- a region the up and down direction of which is surrounded by the end plate 112 and the end plate 117 and which is further surrounded by the wrap 113 and the wrap 118 forms a plurality of crescent-shaped enclosed spaces SA for establishing a compression process.
- the fixed scroll 111 and the orbiting scroll 116 are disposed on a casing-form frame 120 so that the fixed scroll 111 is on the upper side and the orbiting scroll 116 is on the lower side.
- the back surface of the end plate 117 of the orbiting scroll 116 is slidably supported on a horizontal bearing surface 121 formed on the upper surface of the frame 120.
- the upper end of the rotating shaft 110 extends toward the center of the end plate 117 of the orbiting scroll 116 while penetrating the frame 120.
- the upper end part of the rotating shaft 110 is rotatably supported by a bearing 122 provided in the penetration part of the frame 120.
- At the upper end of the rotating shaft 110 there is formed an eccentric pin 123 having the axis at a position off-center from the axis of the rotating shaft 110.
- the eccentric pin 123 is slidably fitted in the boss part 119. Therefore, when the rotating shaft 110 rotates, the orbiting scroll 116 orbits around the axis of the fixed scroll 111.
- a rotation inhibiting mechanism that inhibits the rotation of the orbiting scroll 116 though allowing the orbital motion thereof, for example, an Oldham's ring (not shown) is interposed.
- an Oldham's ring (not shown) is interposed between the peripheral wall 114 of the fixed scroll 111 and the end plate 117 of the orbiting scroll 116 facing to the peripheral wall 114.
- two large and small cylindrical flanges 124 and 125 are formed with the axis of the end plate 112 being the center.
- a discharge cavity 127 is formed between the flanges 124 and 125 and the cover 126.
- the discharge cavity 127 communicates with the discharge port 115 and a discharge pipe 129 connected to the upper wall of the enclosed housing 100, so that the discharged gas discharged into the discharge cavity 127 can be discharged to the outside of the enclosed housing 100.
- the discharge port 115 is provided with a check valve 128 for preventing back flow.
- the rolling piston compression mechanism 101 includes a main bearing body 131 and a subsidiary bearing body 132 that are provided on both sides of a cylinder 130 so as to hold the cylinder 130 therebetween, so that, by utilizing a circular space formed in the cylinder 130, a cylinder chamber 133 is formed in a part interposed between the main bearing body 131 and the subsidiary bearing body 132.
- a rotor 134 and a blade for partitioning the cylinder chamber 133 into the suction side and the discharge side are disposed.
- the rotor 134 is connected to one end part of the rotating shaft 110, which serves as the output shaft of the motor 103, via an eccentric cam part 135, so that the rotor 134 is eccentrically rotated in the cylinder chamber 133 by a driving force generated by the motor 103.
- the rotor 134 is eccentrically rotated in the cylinder chamber 133 by receiving the rotational force from the rotating shaft 110 with the eccentric action of the eccentric cam part 135.
- the working gas is sucked into the cylinder chamber 133 through a suction pipe 136 and a suction port (not shown) of the cylinder chamber 133.
- the working gas compressed in the cylinder chamber 133 is discharged once into the enclosed housing 100 through a discharge port (not shown).
- the gas is compressed from a low pressure to a medium pressure (low-stage compression).
- the eccentric pin 123 is eccentrically rotated by receiving a rotational force from the rotating shaft 110.
- the orbiting scroll 116 is orbited with respect to the fixed scroll 111.
- the volumes of the crescent-shaped enclosed spaces SA formed between the wrap 113 and the wrap 118 are changed with the orbital motion. Therefore, the working gas in the enclosed housing 100 is sucked into the enclosed spaces SA through a passage 137 formed between the frame 120 and the inner peripheral surface of the enclosed housing 100, and is compressed with decreasing the volumes of the enclosed spaces SA.
- the working gas that becomes in a predetermined compressed state is discharged to the outside of the enclosed housing 100 through the discharge port 115 provided in the central part of the fixed scroll 111, the check valve 128, the discharge cavity 127, and the discharge pipe 129.
- the working gas is compressed from the medium pressure to a high pressure (high-stage compression).
- the two-stage compressor of this embodiment features the scroll compression mechanism 102. This feature is explained below.
- Figure 2 is a schematic view showing a cross section of the orbiting scroll 116.
- the above-mentioned condition of L ⁇ Worb also means that the thickness of the end plate 117 of the orbiting scroll 116 can be decreased. Since the thickness of the end plate 117 can be decreased, the weight of the orbiting scroll 116 can be reduced, which contributes to an increase in efficiency of the scroll compression mechanism 102.
- Figure 3 is a schematic view showing a state in which the fixed scroll 111 and the orbiting scroll 116 are combined.
- the orbiting scroll 116 satisfies a condition of 2 ⁇ L/Tr ⁇ 7.
- L/Tr is an index indicating the strength of the wrap 118. If L/Tr is less than 2, the displacement runs short. On the other hand, if L/Tr exceeds 7, the strength of the wrap 118 runs short. That is to say, by satisfying the condition of 2 ⁇ L/Tr ⁇ 7, the strength of the wrap 118 can be secured while securing the displacement.
- the ratio of L/Tr is preferably in the range of 3 ⁇ L/Tr ⁇ 6, further preferably in the range of 3.5 ⁇ L/Tr ⁇ 5.5.
- Figure 4 schematically shows a state in which the orbiting scroll 116 is supported on the frame 120.
- the orbiting scroll 116 taking the outside diameter of the end plate 117 of the orbiting scroll 116 as Dout, the outside diameter of the wrap 118 of the orbiting scroll 116 as Dwrap, and the inside diameter of a support part on the back surface of the orbiting scroll 116 as Db, the orbiting scroll 116 satisfies conditions of Dwrap/Dout ⁇ 0.7 and Db ⁇ Dwrap, that is, a condition of Db ⁇ Dwrap ⁇ 0.7Dout.
- the condition of Dwrap/Dout ⁇ 0.7 means that the area in which the wrap 118 is formed is decreased.
- the application area of thrust load on the orbiting scroll 116 can be decreased.
- the deformation of the end plate 117 of the orbiting scroll 116 can further be reduced.
- the load can be supported by a larger area.
- the thrust surface pressure can be reduced.
- the decrease in area in which the wrap 118 is formed is especially effective in reducing the thrust surface pressure.
- the support point of thrust load is shifted toward the central part of the orbiting scroll 116, by which the deformation of the end plate 117 can be reduced further.
- the above is an explanation of one embodiment of the present invention.
- the present invention is not limited to this embodiment, and can be applied widely to a multistage compressor provided with at least one scroll compression mechanism.
- the present invention can also be applied to a compressor provided with two stages of scroll compression mechanisms or a compressor provided with a scroll compression mechanism on the low pressure side and a rolling piston compression mechanism on the high pressure side.
- the present invention can be applied to any of a low-pressure housing, a high-pressure housing, and a medium-pressure housing.
- the present invention can be applied to a scroll compression mechanism having an orbiting back pressure structure.
- the orbiting back pressure structure is configured so that a back pressure chamber is provided on the back surface of orbiting scroll, and a gas having a pressure higher than the suction pressure (medium pressure or discharge pressure) is introduced into the back pressure chamber, by which the orbiting scroll is pressed against the fixed scroll side.
- the thrust gas force can be reduced (canceled) in a wide range by properly controlling the pressure of gas introduced into the back pressure chamber. Therefore, the deformation of the end plate caused by the thrust gas force is reduced, so that the thickness of the end plate can be decreased.
- the present invention that intends to relatively decrease the thickness of end plate is suitably applied to the scroll compression mechanism having the orbiting back pressure structure.
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Abstract
There is provided a compressor using CO2 as a working gas and capable of having a high capacity. The multistage compressor includes an enclosed housing, a plurality of compression mechanisms provided in the enclosed housing, and a motor for driving the plurality of compression mechanisms, wherein at least one of the plurality of compression mechanisms is a scroll compression mechanism, and a gas including a supercritical state is used as the working gas. The scroll compression mechanism includes a fixed scroll having a spiral wrap formed on one side of an end plate thereof, and an orbiting scroll 116 provided, on one side of an end plate 117 thereof, with a spiral wrap 118 that is combined with the wrap of the fixed scroll to form a spiral compression chamber. The introduced working gas is compressed in the compression chamber as the orbiting scroll 116 orbits. Taking the thickness of the end plate 117 of the orbiting scroll 116 as Worb and the height of the wrap 118 of the orbiting scroll 116 as L, a condition of L ≥ Worb is satisfied.
Description
- The present invention relates to a multistage compressor suitable for a vapor compression refrigerating cycle using carbon dioxide (CO2) as a refrigerant gas (working gas).
- In recent years, from the viewpoint of environmental protection, as one of the CFC-free measures for a refrigerant in a vapor compression refrigerating cycle, a vapor compression refrigerating cycle using CO2 as a working gas has been proposed.
- The critical temperature of CO2 is about 31°C, being lower than the critical temperature of CFC, which is the conventional refrigerant. Therefore, when the open-air temperature is high as in summer, the temperature of CO2 on the radiator side is higher than the critical temperature of CO2, so that CO2 does not condense on the radiator outlet side. Also, the state on the radiator outlet side is determined by the discharge pressure of a compressor and the temperature of CO2 on the radiator outlet side. Since the temperature of CO2 on the radiator outlet side is determined by the radiation capacity of the radiator and the open-air temperature (uncontrollable), the temperature of radiator outlet cannot substantially be controlled. Therefore, the state on the radiator outlet side can be controlled by controlling the discharge pressure of the compressor (pressure on the radiator outlet side). That is to say, when the open-air temperature is high as in summer, the pressure on the radiator outlet side must be increased to ensure sufficient cooling capacity (enthalpy difference). For this purpose, in the vapor compression refrigerating cycle using CO2, the operating pressure of the compressor must be increased to three to five times as compared with the conventional refrigerant cycle using CFC.
- As a compressor used in the vapor compression refrigerating cycle, a scroll compressor is known. The scroll compressor includes, in a casing, a fixed scroll having a spiral wrap formed on one side of the end plate thereof, and an orbiting scroll provided, on one side of the end plate thereof, with a spiral wrap that is combined with the wrap of the fixed scroll to form a spiral compression chamber. The scroll compressor compresses the introduced working gas in the compression chamber and then discharges the working gas with the orbiting of the orbiting scroll.
- In the case where CO2 having a high operating pressure is used as the working gas in the scroll compressor, if the thicknesses of both the end plates of the fixed scroll and the orbiting scroll are smaller than the heights of both the spiral wraps, both the end plates of the fixed scroll and the orbiting scroll are liable to be deflectingly deformed by a load applied at the time of compression. As a result, the sealing ability of the compression chamber decreases. Therefore, the discharge quantity is decreased by the leakage of working gas from the compression chamber, or the temperature of discharged gas is raised by recompression of leaking gas, so that the performance of the compressor degrades inevitably.
- Accordingly, Patent Document 1 has proposed a technique in which the thicknesses T1 and T2 of the end plates of the fixed scroll and the orbiting scroll are made larger than 0.9 times the heights H1 and H2 of the spiral wraps of the fixed scroll and the orbiting scroll, respectively. According to the proposal of Patent Document 1, since the thicknesses of the end plates of the fixed scroll and the orbiting scroll are larger than 0.9 times the heights of the spiral wraps of the fixed scroll and the orbiting scroll, respectively, even in the scroll compressor using CO2 as the working gas, the end plates of the fixed scroll and the orbiting scroll are less liable to be deformed by the load applied at the time of compression, so that the sealing ability of compression chamber is secured.
Patent Document 1: Japanese Patent Laid-Open No.2000-352387 - The proposal of Patent Document 1 contributes to the practical use of the scroll compressor using CO2 as the working gas. The proposal of Patent Document 1, that is, the technique in which the thicknesses T1 and T2 of the end plates of the fixed scroll and the orbiting scroll are made larger than 0.9 times the heights H1 and H2 of the spiral wraps of the fixed scroll and the orbiting scroll, respectively, is based on the decrease in heights of spiral wraps. Therefore, the application of the proposal of Patent Document 1 is limited to a compressor having a relatively low capacity.
- The present invention has been accomplished in view of the above circumstances, and accordingly an object thereof is to provide a compressor using a gas including a supercritical state, typically CO2, as a working gas and capable of having a high capacity.
- The present invention solves the above problems by making the working gas for the multistage compressor including at least one scroll compressor be a gas including a supercritical state, typically CO2. That is to say, the present invention is not configured so that the working gas is compressed from a low pressure to a high pressure by singly using a scroll compressor, but, for example, two compression mechanisms are provided to compress the working gas from a low pressure to a medium pressure by one compression mechanism and from the medium pressure to a high pressure by the other compression mechanism. Thereby, the differential pressure in one compression mechanism can be decreased. Therefore, in the case where a scroll compression mechanism is used as the aforementioned compression mechanism, even if the height of spiral wrap is increased, the deformation of both the end plates of the fixed scroll and the orbiting scroll is restrained, so that the sealing ability of a compression chamber can be secured.
- That is to say, the present invention provides a multistage compressor including an enclosed housing; a plurality of compression mechanisms provided in the enclosed housing; and a motor for driving the plurality of compression mechanisms, wherein at least one of the plurality of compression mechanisms is a scroll compression mechanism, and a gas including a supercritical state is used as a working gas, characterized in that the scroll compression mechanism includes a fixed scroll having a spiral wrap formed on one side of an end plate thereof, and an orbiting scroll provided, on one side of an end plate thereof, with a spiral wrap that is combined with the spiral wrap of the fixed scroll to form a compression chamber, and the introduced working gas is compressed in the compression chamber as the orbiting scroll orbits; and taking the thickness of the end plate of the orbiting scroll as Worb and the height of the spiral wrap of the orbiting scroll as L, a condition of L ≥ Worb is satisfied.
- In the multistage compressor in accordance with the present invention, taking the thickness of the end plate of the fixed scroll as Wfix, a condition of Wfix ≥ L ≥ Worb is preferably satisfied. This condition contributes to the prevention of deformation of the end plate of the fixed scroll.
- Also, in the multistage compressor in accordance with the present invention, taking the thickness of the spiral wrap of the orbiting scroll as Tr, a condition of 2 ≤ L/Tr ≤ 7 is preferably satisfied. Thereby, the strength of the spiral wrap of the orbiting scroll is secured while securing the displacement.
- Further, in the multistage compressor in accordance with the present invention, taking the outside diameter of the end plate of the orbiting scroll as Dout, the outside diameter of the spiral wrap of the orbiting scroll as Dwrap, and the inside diameter of a support part on the back surface of the orbiting scroll as Db, conditions of Dwrap/Dout < 0.7 and Db < Dwrap are preferably satisfied. By specifying in this manner, the deformation of the end plate of the orbiting scroll can further be reduced.
- According to the present invention, in the multistage compressor in which at least one of the plurality of compression mechanisms is a scroll compression mechanism, and CO2 is used as the working gas, taking the thickness of the end plate of the orbiting scroll of the scroll compression mechanism as Worb and the height of the spiral wrap of the orbiting scroll thereof as L, the condition of L ≥ Worb is satisfied. This means that the height of the spiral wrap of the orbiting scroll (fixed scroll) can be increased, so that the capacity of the compressor using CO2 as the working gas can be increased.
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Figure 1 is a sectional view of a two-stage compressor in accordance with an embodiment; -
Figure 2 is a schematic view showing a cross section of an orbiting scroll; -
Figure 3 is a schematic view showing cross sections of a fixed scroll and an orbiting scroll; and -
Figure 4 is a schematic view showing a state in which an orbiting scroll is supported on a frame. - 100 ... enclosed housing, 101 ... rolling piston compression mechanism, 102 ... scroll compression mechanism, 103 ... motor, 111 ... fixed scroll, 112 ... end plate, 113 ... wrap, 116 ... orbiting scroll, 117 ... end plate, 118 ... wrap, SA ... enclosed space
- The present invention will now be described in detail based on an embodiment shown in the accompanying drawings.
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Figure 1 is a longitudinal sectional view showing a configuration of a multistage compressor of this embodiment. - In
Figure 1 , a rollingpiston compression mechanism 101 and ascroll compression mechanism 102 are disposed in an enclosedhousing 100. Between the rollingpiston compression mechanism 101 and thescroll compression mechanism 102, a motor 103 (electric motor) for driving the twocompression mechanisms - In the upper part of the cylindrical enclosed
housing 100 extending along the up and down direction, thescroll compression mechanism 102 is accommodated. Under thescroll compression mechanism 102, the motor 103 (electric motor) is accommodated. Also, between thescroll compression mechanism 102 and themotor 103, a rotatingshaft 110 is disposed. Themotor 103 includes astator 103a that is press fitted in and supported by the inner peripheral part of the enclosedhousing 100 and arotor 103b arranged on the inside of thestator 103a. Therotor 103b is coaxially fixed on the rotatingshaft 110, and the rotation of therotor 103b is output from the rotatingshaft 110. - The
scroll compression mechanism 102 includes afixed scroll 111 the whole of which is made of an iron-based material such as cast iron or carbon steel, and anorbiting scroll 116 made of an iron-based material, which meshes with thefixed scroll 111. - The
fixed scroll 111 includes anend plate 112, aspiral wrap 113 formed on the inner surface of theend plate 112 facing to theorbiting scroll 116, and aperipheral wall 114 surrounding thewrap 113. Also, in the central part of theend plate 112, adischarge port 115 is provided. - The orbiting
scroll 116 includes anend plate 117 and aspiral wrap 118 formed on the inner surface of theend plate 117 facing to thefixed scroll 111. In the central part of the back surface of theend plate 117 facing to the inner surface, acylindrical boss part 119 is projectingly provided. - The
fixed scroll 111 and theorbiting scroll 116 are assembled so that thewrap 113 and thewrap 118 are meshed with each other being shifted through 180 degrees (a predetermined angle). A region the up and down direction of which is surrounded by theend plate 112 and theend plate 117 and which is further surrounded by thewrap 113 and thewrap 118 forms a plurality of crescent-shaped enclosed spaces SA for establishing a compression process. - The fixed
scroll 111 and theorbiting scroll 116 are disposed on a casing-form frame 120 so that the fixedscroll 111 is on the upper side and theorbiting scroll 116 is on the lower side. - The back surface of the
end plate 117 of theorbiting scroll 116 is slidably supported on ahorizontal bearing surface 121 formed on the upper surface of theframe 120. - The upper end of the
rotating shaft 110 extends toward the center of theend plate 117 of theorbiting scroll 116 while penetrating theframe 120. The upper end part of therotating shaft 110 is rotatably supported by abearing 122 provided in the penetration part of theframe 120. At the upper end of therotating shaft 110, there is formed aneccentric pin 123 having the axis at a position off-center from the axis of therotating shaft 110. - The
eccentric pin 123 is slidably fitted in theboss part 119. Therefore, when therotating shaft 110 rotates, theorbiting scroll 116 orbits around the axis of the fixedscroll 111. - Also, between the
peripheral wall 114 of the fixedscroll 111 and theend plate 117 of theorbiting scroll 116 facing to theperipheral wall 114, a rotation inhibiting mechanism that inhibits the rotation of theorbiting scroll 116 though allowing the orbital motion thereof, for example, an Oldham's ring (not shown) is interposed. With the orbital motion of theorbiting scroll 116 obtained by the Oldham's ring and theeccentric pin 123, the volume of the enclosed space SA decreases gradually. With decreasing the volume of the enclosed space SA, a working gas is compressed. - Also, on the back surface of the
end plate 112 of the fixedscroll 111, two large and smallcylindrical flanges end plate 112 being the center. By providing acover 126 above theflanges discharge cavity 127 is formed between theflanges cover 126. Thedischarge cavity 127 communicates with thedischarge port 115 and adischarge pipe 129 connected to the upper wall of theenclosed housing 100, so that the discharged gas discharged into thedischarge cavity 127 can be discharged to the outside of theenclosed housing 100. Thedischarge port 115 is provided with acheck valve 128 for preventing back flow. - The rolling
piston compression mechanism 101 includes amain bearing body 131 and asubsidiary bearing body 132 that are provided on both sides of acylinder 130 so as to hold thecylinder 130 therebetween, so that, by utilizing a circular space formed in thecylinder 130, acylinder chamber 133 is formed in a part interposed between themain bearing body 131 and thesubsidiary bearing body 132. In thecircular cylinder chamber 133, arotor 134 and a blade (not shown) for partitioning thecylinder chamber 133 into the suction side and the discharge side are disposed. Therotor 134 is connected to one end part of therotating shaft 110, which serves as the output shaft of themotor 103, via aneccentric cam part 135, so that therotor 134 is eccentrically rotated in thecylinder chamber 133 by a driving force generated by themotor 103. - When the
motor 103 is energized, the rotational force of themotor 103 is transmitted to the rollingpiston compression mechanism 101 and thescroll compression mechanism 102 through therotating shaft 110. - In the rolling
piston compression mechanism 101, therotor 134 is eccentrically rotated in thecylinder chamber 133 by receiving the rotational force from therotating shaft 110 with the eccentric action of theeccentric cam part 135. Thereby, the working gas is sucked into thecylinder chamber 133 through asuction pipe 136 and a suction port (not shown) of thecylinder chamber 133. The working gas compressed in thecylinder chamber 133 is discharged once into theenclosed housing 100 through a discharge port (not shown). By the compressing action in the rollingpiston compression mechanism 101, the gas is compressed from a low pressure to a medium pressure (low-stage compression). - On the other hand, in the
scroll compression mechanism 102, theeccentric pin 123 is eccentrically rotated by receiving a rotational force from therotating shaft 110. Thereby, theorbiting scroll 116 is orbited with respect to the fixedscroll 111. Thereby, the volumes of the crescent-shaped enclosed spaces SA formed between thewrap 113 and thewrap 118 are changed with the orbital motion. Therefore, the working gas in theenclosed housing 100 is sucked into the enclosed spaces SA through apassage 137 formed between theframe 120 and the inner peripheral surface of theenclosed housing 100, and is compressed with decreasing the volumes of the enclosed spaces SA. - The working gas that becomes in a predetermined compressed state is discharged to the outside of the
enclosed housing 100 through thedischarge port 115 provided in the central part of the fixedscroll 111, thecheck valve 128, thedischarge cavity 127, and thedischarge pipe 129. By the compressing action in thescroll compression mechanism 102, the working gas is compressed from the medium pressure to a high pressure (high-stage compression). - The two-stage compressor of this embodiment features the
scroll compression mechanism 102. This feature is explained below. -
Figure 2 is a schematic view showing a cross section of theorbiting scroll 116. - In
Figure 2 , taking the thickness of theend plate 117 of theorbiting scroll 116 as Worb and the height of thewrap 118 of the orbiting scroll 116 (= the height of thewrap 113 of the fixed scroll 111) as L, theorbiting scroll 116 satisfies a condition of L ≥ Worb. This means that the height of thewrap 118 can be increased. Therefore, the two-stage compressor of this embodiment can achieve high capacity. The reason why the condition of L ≥ Worb can be satisfied in thescroll compression mechanism 102 is that a two-stage compression mechanism consisting of the rollingpiston compression mechanism 101 and thescroll compression mechanism 102 is used, by which the differential pressure in each of these compression mechanisms can be decreased. The above-mentioned condition of L ≥ Worb also means that the thickness of theend plate 117 of theorbiting scroll 116 can be decreased. Since the thickness of theend plate 117 can be decreased, the weight of theorbiting scroll 116 can be reduced, which contributes to an increase in efficiency of thescroll compression mechanism 102. -
Figure 3 is a schematic view showing a state in which the fixedscroll 111 and theorbiting scroll 116 are combined. - In
Figure 3 , taking the thickness of theend plate 112 of the fixedscroll 111 as Wfix, the fixedscroll 111 and theorbiting scroll 116 satisfy a condition of Wfix ≥ L ≥ Worb. A discharge pressure (high pressure) acts on the back surface of the fixedscroll 111. Therefore, the fixedscroll 111 tends to deform so that the lower side thereof is convex. Since the fixedscroll 111 satisfies the condition of Wfix ≥ L ≥ Worb, that is, the thickness of theend plate 112 of the fixedscroll 111 is set so as to be large, for thescroll compression mechanism 102, the deformation of theend plate 112 is restrained, and in turn, the leakage of working gas can be reduced while enjoying an advantage of high capacity. - In
Figure 2 , taking the thickness of thewrap 118 of theorbiting scroll 116 as Tr, theorbiting scroll 116 satisfies a condition of 2 ≤ L/Tr ≤ 7. It can be said that L/Tr is an index indicating the strength of thewrap 118. If L/Tr is less than 2, the displacement runs short. On the other hand, if L/Tr exceeds 7, the strength of thewrap 118 runs short. That is to say, by satisfying the condition of 2 ≤ L/Tr ≤ 7, the strength of thewrap 118 can be secured while securing the displacement. The ratio of L/Tr is preferably in the range of 3 ≤ L/Tr ≤ 6, further preferably in the range of 3.5 ≤ L/Tr ≤ 5.5. -
Figure 4 schematically shows a state in which theorbiting scroll 116 is supported on theframe 120. InFigure 4 , taking the outside diameter of theend plate 117 of theorbiting scroll 116 as Dout, the outside diameter of thewrap 118 of theorbiting scroll 116 as Dwrap, and the inside diameter of a support part on the back surface of theorbiting scroll 116 as Db, theorbiting scroll 116 satisfies conditions of Dwrap/Dout < 0.7 and Db < Dwrap, that is, a condition of Db < Dwrap < 0.7Dout. The condition of Dwrap/Dout < 0.7 means that the area in which thewrap 118 is formed is decreased. Thereby, the application area of thrust load on theorbiting scroll 116 can be decreased. By reducing the thrust load, the deformation of theend plate 117 of theorbiting scroll 116 can further be reduced. On the other hand, by securing the area of the outer peripheral part (the part in which thewrap 118 is not formed) of theend plate 117, the load can be supported by a larger area. Thereby, the thrust surface pressure can be reduced. In the case where CO2 is used as the working gas as in this embodiment, the decrease in area in which thewrap 118 is formed is especially effective in reducing the thrust surface pressure. Also, by satisfying the condition of Db < Dwrap, the support point of thrust load is shifted toward the central part of theorbiting scroll 116, by which the deformation of theend plate 117 can be reduced further. - The above is an explanation of one embodiment of the present invention. The present invention is not limited to this embodiment, and can be applied widely to a multistage compressor provided with at least one scroll compression mechanism. For example, the present invention can also be applied to a compressor provided with two stages of scroll compression mechanisms or a compressor provided with a scroll compression mechanism on the low pressure side and a rolling piston compression mechanism on the high pressure side.
- Also, the present invention can be applied to any of a low-pressure housing, a high-pressure housing, and a medium-pressure housing.
- Further, the present invention can be applied to a scroll compression mechanism having an orbiting back pressure structure. The orbiting back pressure structure is configured so that a back pressure chamber is provided on the back surface of orbiting scroll, and a gas having a pressure higher than the suction pressure (medium pressure or discharge pressure) is introduced into the back pressure chamber, by which the orbiting scroll is pressed against the fixed scroll side. For the scroll compression mechanism having the orbiting back pressure structure, the thrust gas force can be reduced (canceled) in a wide range by properly controlling the pressure of gas introduced into the back pressure chamber. Therefore, the deformation of the end plate caused by the thrust gas force is reduced, so that the thickness of the end plate can be decreased. Thereupon, the present invention that intends to relatively decrease the thickness of end plate is suitably applied to the scroll compression mechanism having the orbiting back pressure structure.
Claims (5)
- A multistage compressor comprising:an enclosed housing;a plurality of compression mechanisms provided in the enclosed housing; anda motor for driving the plurality of compression mechanisms, whereinat least one of the plurality of compression mechanisms is a scroll compression mechanism, and a gas including a supercritical state is used as a working gas,characterized in that
the scroll compression mechanism includes a fixed scroll having a spiral wrap formed on one side of an end plate thereof, and an orbiting scroll provided, on one side of an end plate thereof, with a spiral wrap which is combined with the spiral wrap of the fixed scroll to form a compression chamber, and the introduced working gas is compressed in the compression chamber as the orbiting scroll orbits; and
taking the thickness of the end plate of the orbiting scroll as Worb and the height of the spiral wrap of the orbiting scroll as L,
a condition of L ≥ Worb is satisfied. - The multistage compressor according to claim 1, characterized in that
taking the thickness of the end plate of the fixed scroll as Wfix,
a condition of Wfix ≥ L ≥ Worb is satisfied. - The multistage compressor according to claim 1, characterized in that
taking the thickness of the spiral wrap of the orbiting scroll as Tr,
a condition of 2 ≤ L/Tr ≤ 7 is satisfied. - The multistage compressor according to claim 1, characterized in that
taking the outside diameter of the end plate of the orbiting scroll as Dout, the outside diameter of the spiral wrap of the orbiting scroll as Dwrap, and the inside diameter of a support part on the back surface of the orbiting scroll as Db,
conditions of Dwrap/Dout < 0.7 and Db < Dwrap are satisfied. - The multistage compressor according to claim 1, characterized in that the working gas is carbon dioxide (CO2).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2007073865A JP2008232041A (en) | 2007-03-22 | 2007-03-22 | Multistage compressor |
PCT/JP2008/055224 WO2008114860A1 (en) | 2007-03-22 | 2008-03-21 | Multistage compressor |
Publications (1)
Publication Number | Publication Date |
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EP2053247A1 true EP2053247A1 (en) | 2009-04-29 |
Family
ID=39765960
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP08722588A Withdrawn EP2053247A1 (en) | 2007-03-22 | 2008-03-21 | Multistage compressor |
Country Status (4)
Country | Link |
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EP (1) | EP2053247A1 (en) |
JP (1) | JP2008232041A (en) |
CN (1) | CN101617123A (en) |
WO (1) | WO2008114860A1 (en) |
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CN113482923B (en) * | 2021-08-27 | 2022-09-09 | 广东美的环境科技有限公司 | Compression assembly, scroll compressor and air conditioner |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH07103167A (en) * | 1993-09-30 | 1995-04-18 | Mitsubishi Heavy Ind Ltd | Two-stage compressor |
JP4043144B2 (en) | 1999-06-08 | 2008-02-06 | 三菱重工業株式会社 | Scroll compressor |
JP2004197640A (en) * | 2002-12-18 | 2004-07-15 | Daikin Ind Ltd | Positive displacement expander and fluid machinery |
JP4440564B2 (en) * | 2003-06-12 | 2010-03-24 | パナソニック株式会社 | Scroll compressor |
JP2005083235A (en) * | 2003-09-08 | 2005-03-31 | Matsushita Electric Ind Co Ltd | Scroll compressor |
JP2006144635A (en) * | 2004-11-18 | 2006-06-08 | Denso Corp | Scroll compressor |
-
2007
- 2007-03-22 JP JP2007073865A patent/JP2008232041A/en active Pending
-
2008
- 2008-03-21 WO PCT/JP2008/055224 patent/WO2008114860A1/en active Application Filing
- 2008-03-21 CN CN200880005615A patent/CN101617123A/en active Pending
- 2008-03-21 EP EP08722588A patent/EP2053247A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
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See references of WO2008114860A1 * |
Also Published As
Publication number | Publication date |
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JP2008232041A (en) | 2008-10-02 |
CN101617123A (en) | 2009-12-30 |
WO2008114860A1 (en) | 2008-09-25 |
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