Sealed Scroll Compressor for Helium
A sealed scroll compressor for helium having a stationary scroll, an orbiting scroll, and an oil-injection mechanism. The oil-injection mechanism has an oil-injection pipe arranged to pass through a sealed container and connected to an oil-injection port, and the opening of the oil-injection port is arranged at a bottom surface of a groove between ridges formed with the scroll wrap of the stationary scroll in such a manner that a first range of the orbital angle of the orbiting scroll is approximately identical to a second range of the orbital angle of the orbiting scroll, where the oil-injection port is connected to the outer compression chamber while the orbital angle of the orbiting scroll is in the first range, and is connected to the inner compression chamber while the orbital angle of the orbiting scroll is in the second range.
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This application claims the foreign priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2011-110004, filed on May 17, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a sealed scroll compressor for use in refrigeration or air conditioning, and in particular to a sealed scroll compressor for helium.
2. Description of the Related Art
An example of a sealed scroll compressor for helium is disclosed in Japanese Patent Laid-open No. 2009-156234 (hereinafter referred to as JP2009-156234A).
The sealed scroll compressor disclosed in JP2009-156234A has an oil-injection mechanism, in which an oil-injection pipe for cooling the working helium gas is arranged through the wall of a sealed container and is connected to an oil-injection port arranged in an end plate of the stationary scroll. However, the flow rate of the first injected cooling oil into the outer compression chamber on the outer side of the scroll and the flow rate of the second injected cooling oil into the inner compression chamber on the inner side of the scroll are unbalanced, where the outer compression chamber is formed between the outer curved surface of the orbiting scroll (orbital scroll) and the inner curved surface of the stationary scroll, and the inner compression chamber is formed between the inner curved surface of the orbiting scroll and the outer curved surface of the stationary scroll. In other words, the injected cooling oil is not equally distributed to the inner compression chamber and the outer compression chamber in the conventional scroll compressor.
In view of the above, the object of the present invention is to improve the performance of the sealed scroll compressor.
SUMMARY OF THE INVENTIONIn order to achieve the above object, according to the first aspect of the present invention, a sealed scroll compressor for helium is provided. The sealed scroll compressor includes: a sealed container; a stationary scroll being contained in the sealed container and having an end plate and a scroll wrap; an oil-injection port having an opening and being arranged in the end plate of the stationary scroll; an oil-injection mechanism having an oil-injection pipe which is arranged to pass through the sealed container and connected to the oil-injection port; and an orbiting scroll contained in the sealed container and interleaved with the stationary scroll to form an outer compression chamber and an inner compression chamber which realize an asymmetric-wrap type compression chambers. The opening of the oil-injection port is arranged at a bottom surface of a groove between ridges formed with the scroll wrap of the stationary scroll in such a manner that a first range of an orbital angle of the orbiting scroll is approximately identical to a second range of the orbital angle of the orbiting scroll, where the oil-injection port is connected to the outer compression chamber while the orbital angle of the orbiting scroll is in the first range, and is connected to the inner compression chamber while the orbital angle of the orbiting scroll is in the second range.
In addition, in order to achieve the aforementioned object, according to the second aspect of the present invention, a sealed scroll compressor for helium is provided. The sealed scroll compressor includes: a sealed container; a stationary scroll being contained in the sealed container and having an end plate and a scroll wrap; an oil-injection port having an opening and being arranged in the end plate of the stationary scroll; an oil-injection mechanism having an oil-injection pipe which is arranged to pass through the sealed container and connected to the oil-injection port; and an orbiting scroll contained in the sealed container and interleaved with the stationary scroll to form an outer compression chamber and an inner compression chamber which realize an asymmetric-wrap type compression chambers. The opening of the oil-injection port is arranged at a bottom surface of a groove between ridges formed with the wrap of the stationary scroll in such a manner that a first range θ1 of an orbital angle of the orbiting scroll, a second range θ2 of the orbital angle of the orbiting scroll, a first stroke volume Vth1 in the outer compression chamber, and a second stroke volume Vth2 in the inner compression chamber satisfy a relationship,
θ1/θ2≈Vth1/Vth2.
According to the present invention, the performance of the compressor is improved.
Hereinbelow, the embodiment of the present invention and variations are explained with reference to
First, the structure of the sealed scroll compressor according to the embodiment of the present invention and the flow of working helium gas and the flow of injected cooling oil are explained below with reference to
Compression chambers 8a and 8b (which may be collectively referred to as the compression chambers 8) are formed in the scroll compressor mechanism by interleaving the stationary scroll 5 and the orbiting scroll 6 as illustrated in
A motor shaft 14b is integrally coupled to the rotating shaft 14, and is directly connected to the motor unit 3. The intake pipe 17 passes through the upper cover 2a of the sealed container 1, and is connected to the intake port 15 of the stationary scroll 5.
The discharge chamber 1a has the discharge port 10 as an opening, so that the discharge chamber 1a is connected to the motor chamber 1b through first paths 18a and 18b, which are arranged in peripheral regions of the frame 7. The motor chamber 1b is connected to a discharge pipe 20, which passes through a casing 2b. The casing 2b constitutes the central part of the sealed container 1. The discharge pipe 20 is located on the side of the sealed container 1 nearly opposite to the first paths 18a and 18b. The motor chamber 1b is separated by a (motor) stator 3a into an upper space 1b1 and a lower space 1b2. In addition, in order to allow the oil and gas to flow between the upper space 1b1 and the lower space 1b2, the upper space 1b1 and the lower space 1b2 are connected through paths 25b and 25c (which may be collectively referred to as the paths 25). The paths 25b and 25c are formed in the gaps between the motor stator 3a and the inner wall surface 2m of the casing 2b.
Further, the upper space 1b1 and the lower space 1b2 are also connected through the motor air gap 26. Since a mixture of the gas and the cooling oil flows in the motor chamber 1b through the above paths, the motor can be directly cooled with the injected oil, the temperature of which is relatively low (e.g., 60° C. to 70° C.).
An O-ring 53 is arranged between the intake pipe 17 and the stationary scroll 5 for hermetically separating the high-pressure region and the low-pressure region. In addition, a back-pressure chamber 36 is realized by the space located on the rear side of the end plate of the orbiting scroll 6. That is, the back-pressure chamber 36 is a space enclosed by the scroll compressor mechanism and the frame 7. An intermediate pressure between the intake pressure Ps and the discharge pressure Pd is introduced into the back-pressure chamber 36 through a pore 6d perforated through the end plate of the orbiting scroll 6, so that the intermediate pressure exerts force in the axial direction to the orbiting scroll 6, and presses the orbiting scroll 6 to the stationary scroll 5.
Lubricating oil 23 is reserved at the bottom of the sealed container 1. The lubricating oil 23 is sucked into an oil-suction tube 27 by the centrifugal pump effect which is produced by an eccentric cavity 13 arranged in the rotating shaft 14, flows in the rotating shaft 14, and is then supplied to a scroll bearing 32. The oil supplied to the scroll bearing 32 and discharged from the scroll bearing 32 drops to the main bearing 40 (which is a roller bearing), moves to the bottom end of the frame, is lead through a discharge tube 74, and returns to an oil reservoir in a bottom chamber 2c. In addition, the oil supplied to the scroll bearing 32 and discharged from the scroll bearing 32 moves to the back-pressure chamber 36 through a sealing means 85 which has a ring-shaped sealing structure.
As illustrated in
In order to drain the lubricating oil 23 accumulated at the bottom of the sealed container 1, an injected-oil outlet part 29 is arranged through the bottom of the sealed container 1, and an oil-drain pipe 30 is connected to the injected-oil outlet part 29. The lubricating oil 23 accumulated at the bottom of the sealed container 1 flows into the inflow part 30a of the outlet part 29 and flows through the oil-drain pipe 30 due to the difference between the discharge pressure Pd in the sealed container 1 and the internal pressures Pi1 and Pi2 (which may be collectively referred to as Pi) of the compression chambers 8. Further, a bore reduction means 30m is arranged in the path 30f inside the injected-oil outlet part 29, where the bore reduction means 30m has a diameter equivalent to the diameter of a bore reduction means 31m which is arranged in oil-injection piping.
Although the arrangement around the oil-injection pipe 31 are explained in detail later, the bore reduction means 31m is arranged in a path 31f which is located inside the oil-injection pipe 31 immediately in front of the oil-injection port 22 of the oil-injection pipe 31, where the diameter of the bore reduction means 31m is smaller than the diameter d0 of the oil-injection port 22.
In the plane view illustrated in
In order to cool the body of the compressor and lower the temperature of the helium gas which is heated by adiabatic compression, the sealed scroll compressor according to the present invention has the structure for injection of oil for cooling. In the structure, the oil-injection port 22 is a single port, and is slightly displaced outward, in the plane view parallel to the end plate 5a, from the center of a groove between ridges formed with the wrap 5b as illustrated in
As illustrated in
In order to achieve the above effect, the center 22f of the oil-injection port 22 is slightly displaced outward (i.e., toward the inner surface 561 of the stationary scroll 5) from the center of the groove between the ridges formed with the wrap 5b, as illustrated in the plane view of
In the plane view of
As mentioned before, the opening of the oil-injection port 22 is arranged at the bottom surface 5m of the groove between the ridges formed with the wrap 5b in the stationary scroll 5. In this case, the range (width) θ1 of the orbital angle in which the outer compression chamber 8a is connected to the oil-injection port 22 and the range (width) θ2 of the orbital angle in which the inner compression chamber 8b is connected to the oil-injection port 22 can be set to make the ratio θ1/θ2 as great as (nearly equal to) the ratio V0=Vth1/Vth2. In the example of
Since the means for equally distributing the injected oil according to the present embodiment can relatively reduce the variations in the pressure difference in oil injection (i.e., the differences between the discharge pressure Pd and the pressures Pi1 and Pi2 in the outer and inner compression chambers 8a and 8b) and reduce the oil hammer effect which is caused when the oil is injected. Therefore, it is possible to reduce vibration in the oil injection piping and the piping stress. Further, it is possible to suppress the flow sound (pulsating sound) inside the oil-injection piping, and therefore reduce the noise and vibration of the compressor.
The sealed scroll compressors according to the present embodiment and the first and second variations are characterized in that the center of the opening of the oil-injection port 22, 228, or 222 is located at a position displaced from the end 63 or 64 of the scroll wrap 5b toward the inner end (at the origin Ok) of the wrap 5b along the scroll of the wrap 5b by the scroll wrap angle Δλ0 of approximately 1.5 π to 2 π rad, where π is the circle ratio.
In the sealed scroll compressors according to the present embodiment and the first and second variations, the oil flowing into the oil-drain pipe 30 passes through external oil piping 51 and is then inputted into an oil cooler 33. After the oil is cooled in the oil cooler 33, the cooled oil passes through the oil-injection pipe 31 and the oil-injection port 22 (or 228 or 222) and is injected into the outer and inner compression chambers 8a and 8b. As illustrated in
The structures and mechanisms explained above enables equal distribution of the injected cooling oil into the outer and inner compression chambers, and achieves uniformity in the cooling performance. As indicated in the curves indicating variations of the pressures Pi1 and Pi2 in the pressure chambers in the embodiment and the curves indicating variations of the pressures Pi3 and Pi4 in the pressure chambers in the conventional sealed scroll compressor, the oil-injection function which equally distributes the injected oil to the outer and inner compression chambers 8a and 8b enhances the effect of the cooling oil in isolating the outer and inner compression chambers from each other, so that the rates of the pressure increase (indicated by the compression curves) in the present embodiment is lower than the conventional sealed scroll compressor. Therefore, for example, the pressure difference (ΔP2) between the adjacent compression chambers in the present embodiment is smaller than the pressure difference (ΔP1) between the adjacent compression chambers in the conventional sealed scroll compressor. The decrease in the pressure difference between the adjacent compression chambers reduces the internal leakage and the compression power, and increases the volume efficiency. Thus, the performance and the efficiency of the compressor are greatly improved. In addition, the cooling oil equally distributed to the outer and inner compression chambers 8a and 8b enhances the effects of cooling and isolating the working gas in the outer and inner compression chambers 8a and 8b, and achieves thorough and effective lubrication of the sliding parts such as the edges of the scroll wraps. Further, since the compression power is reduced, the loads acting on the sliding parts such as the bearings are also reduced, so that the reliability of the compressor increases. Furthermore, the decrease in the bearing loads increases the lifetimes of the antifriction bearings such as the main bearing 40 and the scroll bearing 64.
Claims
1. A sealed scroll compressor for helium, comprising:
- a sealed container;
- a stationary scroll being contained in the sealed container and having an end plate and a scroll wrap;
- an oil-injection port having an opening and being arranged in the end plate of the stationary scroll;
- an oil-injection mechanism having an oil-injection pipe which is arranged to pass through the sealed container and connected to the oil-injection port; and
- an orbiting scroll contained in the sealed container and interleaved with the stationary scroll to form an outer compression chamber and an inner compression chamber which realize an asymmetric-wrap type compression chambers;
- wherein the opening of the oil-injection port is arranged at a bottom surface of a groove between ridges formed with the scroll wrap of the stationary scroll in such a manner that a first range of an orbital angle of the orbiting scroll is approximately identical to a second range of the orbital angle of the orbiting scroll, and the oil-injection port is connected to the outer compression chamber while the orbital angle of the orbiting scroll is in the first range, and is connected to the inner compression chamber while the orbital angle of the orbiting scroll is in the second range.
2. The sealed scroll compressor according to claim 1, wherein a center of the opening is displaced outward from a center of the bottom surface.
3. The sealed scroll compressor according to claim 1, wherein the opening has a shape elongated in a radial direction of the stationary scroll.
4. The sealed scroll compressor according to claim 1, wherein each of the first range and the second range has a width of approximately 200 to 230 degrees.
5. The sealed scroll compressor according to claim 1, wherein a center of the opening is located at a position displaced from an end of the scroll wrap of the stationary scroll toward an inner end of the scroll wrap of the stationary scroll along the scroll wrap of the stationary scroll by a scroll wrap angle of approximately 1.5 π to 2 π rad, where it is the circle ratio.
6. A sealed scroll compressor for helium, comprising:
- a sealed container;
- a stationary scroll being contained in the sealed container and having an end plate and a scroll wrap;
- an oil-injection port having an opening and being arranged in the end plate of the stationary scroll;
- an oil-injection mechanism having an oil-injection pipe which is arranged to pass through the sealed container and connected to the oil-injection port; and
- an orbiting scroll contained in the sealed container and interleaved with the stationary scroll to form an outer compression chamber and an inner compression chamber which realize an asymmetric-wrap type compression chambers;
- wherein the opening of the oil-injection port is arranged at a bottom surface of a groove between ridges formed with the wrap of the stationary scroll in such a manner that a first range θ1 of an orbital angle of the orbiting scroll, a second range θ2 of the orbital angle of the orbiting scroll, a first stroke volume Vth1 in the outer compression chamber, and a second stroke volume Vth2 in the inner compression chamber satisfy a relationship, θ1/θ2≈Vth1/Vth2.
7. The sealed scroll compressor according to claim 6, wherein a center of the opening is displaced outward from a center of the bottom surface.
8. The sealed scroll compressor according to claim 6, wherein the opening has a shape elongated in a radial direction of the stationary scroll.
9. The sealed scroll compressor according to claim 6, wherein a center of the opening is located at a position displaced from an end of the scroll wrap of the stationary scroll toward an inner end of the scroll wrap of the stationary scroll along the scroll wrap of the stationary scroll by a scroll wrap angle of approximately 1.5 π to 2 π rad, where n is the circle ratio.
Type: Application
Filed: May 16, 2012
Publication Date: Nov 22, 2012
Applicant: Hitachi Appliances, Inc. (Tokyo)
Inventors: Masao Shiibayashi (Shizuoka), Yasushi Izunaga (Shizuoka-shi), Takamasa Adachi (Shizuoka)
Application Number: 13/473,331
International Classification: F01C 1/02 (20060101);