Patent Application
20130236344
1. Technical Field
The invention relates to a scroll fluid machine such as a compressor, a vacuum pump, a blower, and an expander.
2. Background Art
A scroll compressor is proposed, which is configured to drive the center part of an orbiting scroll having wraps on both sides such that an orbiting scroll performs an orbiting motion. For example, a scroll fluid machine as described in Japanese published unexamined application JP,2010-77913,A (8 Apr. 2010) is configured such that a drive shaft passes through the hollow portion of the center part of the orbiting scroll and the drive shaft is rotatably supported on both sides. The intermediate part of the drive shaft passing through the center part of the orbiting scroll is an eccentric shaft. An eccentric bearing is provided between the eccentric shaft and the orbiting scroll.
In a conventional scroll fluid machine, a orbiting bearing is provided in the hollow portion of the center part of an orbiting scroll. Fluid is subjected to a change in temperature due to compression when using a compressor or a vacuum pump, whereby the center part of the orbiting scroll is heated to a high temperature. In an expander, since high-temperature high-pressure fluid inflows, the center part of the orbiting scroll is heated to a high temperature. Thus, there has been a problem that the orbiting bearing is heated to a high temperature, thereby reducing the durability of the orbiting bearing.
The present invention addresses the aforementioned problem and an object of the present invention is to provide a scroll fluid machine which has a high-durability orbiting bearing.
In the invention according to claim 1, a scroll fluid machine is constituted of a combination of an orbiting scroll that has a spiral wrap on both surfaces of a paneling and a pair of fixed scrolls that has a spiral wrap on one surface of a paneling, wherein a hollow orbiting shaft is provided at the center part of said orbiting scroll to pass through said fixed scroll; a rotating shaft passes through the hollow portion of said orbiting shaft such that it is rotatably supported by a pair of covers provided on the outer surface side of said fixed scroll; orbiting bearings are provided on both ends of said orbiting shaft to fit an eccentric portion provided on said rotating shaft; and a self-rotation prevention mechanism of said orbiting scroll is provided on one end of said orbiting shaft.
In the invention according to claim 2, said eccentric portion is provided only at the position of said rotating shaft corresponding to said orbiting bearing, and the intermediate portion between the eccentric portions of said rotating shaft is formed coaxially with the rotation center axis.
In the invention according to claim 3, said self-rotation prevention mechanism is constituted of a pair of fixed-side key grooves provided coupled with said fixed scroll on one side; a pair of orbiting-side key grooves provided so as to cross orthogonally to said fixed-side key grooves in an orbiting bearing housing which is provided on said orbiting shaft to accommodate said orbiting bearing; and an Oldham's ring having a pair of Oldham's keys fitting said fixed-side key grooves and a pair of Oldham's keys fitting said orbiting-side key grooves.
In the invention according to claim 4, a 1st balance weight is attached to said rotating shaft between said orbiting bearing at one end of said orbiting shaft and the rotating shaft bearing rotatably supporting said rotating shaft at said one cover; and a 2nd balance weight is attached to said rotating shaft between said orbiting bearing at the other end of said orbiting shaft and the rotating shaft bearing rotatably supporting said rotating shaft at said the other cover.
In the invention according to claim 1, orbiting bearings which support an orbiting shaft provided at the center part of an orbiting scroll are arranged on both sides of the orbiting shaft and the orbiting bearing is not located at the center part of the orbiting scroll, whereby the heat of orbiting scroll is hardly transmitted to the orbiting bearing. Even if the center part of the orbiting scroll is heated to a high temperature, the orbiting bearing is not heated to a high temperature. Thus, the durability of the orbiting bearing is increased. Further, the diameter of the orbiting shaft can be reduced, whereby the diameter of the orbiting scroll can be reduced. Hereby, a scroll fluid machine can be made compact.
In the invention according to claim 2, the eccentric portion of the rotating shaft is provided only at two positions of the orbiting bearing. Other portions of the rotating shaft are not eccentrically formed. A centrifugal force is not generated in portions which are not eccentrically formed. Thereby, the deformation of the rotating shaft is reduced. As such, the vibration of the scroll fluid machine is also reduced.
In the invention according to claim 3, the housing of the orbiting bearing is also a component of a self-rotation prevention mechanism, whereby the number of components used in the scroll fluid machine is reduced.
In the invention according to claim 4, the distance between a 1st and a 2nd balance weights and an orbiting bearing can be reduced, whereby a moment applied to a rotating shaft can be reduced, thus the deformation of the shaft can be suppressed.
A hollow orbiting shaft 1D is provided radially in the center part of the paneling 1A. A 1st orbiting bearing housing 11 is fixed to one end of the orbiting shaft 1D in the axial direction. A 1st orbiting bearing 12 is provided at the center part of the 1st orbiting bearing housing 11. A 2nd orbiting bearing housing 13 is fixed to the other end of the orbiting shaft 1D in the axial direction. A 2nd orbiting bearing 14 is provided at the center part of the 2nd orbiting bearing housing 13. A rotating shaft 6 passes through the hollow portion of the orbiting shaft 1D. A cylindrical portion 2C is provided on the back surface of the 1st fixed scroll 2. A cover 7 is arranged on the end face of the cylindrical portion 2C. A 1st rotating shaft bearing 8 is provided on the center part of the cover 7. A cylindrical portion 3C is provided on the back surface of the 2nd fixed scroll 3. A cover 9 is arranged on the end face of the cylindrical portion 3C. A 2nd rotating shaft bearing 10 is provided on the center part of the cover 9. The one end 6C of the rotating shaft 6 is supported by the 1st rotating shaft bearing 8. The edge of the rotating shaft 6 passes through the cover 7 and extends outside the cover 7. A sealing member 15 is provided on the center part of the cover 7 so as to seal between the rotating shaft 6 and the cover 7. The other end 6D of the rotating shaft 6 is supported by the 2nd rotating shaft bearing 10. Eccentric portions 6A and 6B are formed at two positions of the rotating shaft 6. The intermediate portion between the eccentric portion 6A and the eccentric portion 6B of the rotating shaft 6 is formed coaxially with the rotation center axis of the rotating shaft 6. The 1st orbiting bearing 12 fits the eccentric portion 6A. The 2nd orbiting bearing 14 fits the eccentric portion 6B. That is, the eccentric portions 6A and 6B are provided only on the positions corresponding to the 1st orbiting bearing 12 and the 2nd orbiting bearing 14 of the rotating shaft 6.
The 1st orbiting bearing housing 11 has a flange portion 11A. The flange portion 11A has orbiting-side key grooves 11B, 11B. A fixed board 16 is fixed to the inner surface of the cylindrical portion 2C. An Oldham's ring 17 fits in between the flange portion 11A and the fixed board 16. The Oldham's ring 17 has Oldham's keys 17A, 17A. The Oldham's keys 17A, 17A fit the orbiting-side key grooves 11B, 11B.
The 1st orbiting bearing housing 11 has a sealing board 11C. A sealing ring 18 is provided on the paneling 2A so as to seal between the sealing board 11C and the paneling 2A.
The 2nd orbiting bearing housing 13 has a flange portion 13A, while a sealing board 19 is attached to the inner surface of the cylindrical portion 3C.
A sealing ring 20 is provided on the outer peripheral surface of the sealing board 19. A sealing ring 21 is provided on the end face of the sealing board 19. The sealing ring 20 and the sealing ring 21 seal between the inner surface of the cylindrical portion 3C and the end face of the flange portion 13A, and the sealing board 19.
A weight chamber 27 is formed between the cover 7 and the 1st orbiting bearing housing 11. A 1st balance weight 22 is attached between the 1st rotating shaft bearing 8 of the rotating shaft 6 and the 1st orbiting bearing 12, in the weight chamber 27. A weight chamber 28 is formed between the cover 9 and the 2nd orbiting bearing housing 13. A 2nd balance weight 23 is attached between the 2nd rotating shaft bearing 10 of the rotating shaft 6 and the 2nd orbiting bearing 14, in the weight chamber 28.
An inlet 24 is provided on the outer peripheral portion of the fixed scroll 2. An opening 38 is provided on the paneling 1A adjacent to the orbiting shaft 1D. An outlet chamber 25 is provided on the backside of the paneling 3A of the fixed scroll 3. An outlet 26 is provided on the outer peripheral portion of the paneling 3A. A compressor is installed on one side 37A of a base 37.
An electric motor 29 is placed on the other side 37B of the base 37. A drive shaft 29A of the electric motor 29 and one end 6C of the rotating shaft 6 are coaxially arranged, and connected to each other with a coupling 30 while being prevented from rotating by a key and so forth.
An oil tank 31 is installed. Lubricant oil 32 is reserved in the oil tank 31. An oil inlet tube 33 is connected to the bottom of the oil tank 31, and is connected to the entrance of a pump 34. An oil feed tube 35 is connected to the exit of the pump 34, and is communicated with the top of the weight chamber 27 and the weight chamber 28. An oil return tube 36 is connected to the bottom of the weight chamber 27 and the weight chamber 28, and is communicated with the oil tank 31.
Next, the operation of the compressor is described. When the electric motor 29 is energized, the drive shaft 29A rotates, and the rotating shaft 6 which is coupled with the drive shaft 29A rotates. When the rotating shaft 6 rotates, the orbiting shaft 1D is eccentrically driven while being prevented from self-rotating by the self-rotation prevention mechanism. As a result, the orbiting scroll 1 which is integrally formed with the orbiting shaft 1D performs orbiting motion. Thereby gas moves from the outer periphery to the inner periphery in the compression chamber 4 and the compression chamber 5 while being reduced in volume. Gas is inleted through an inlet 24, is compressed in the compression chamber 4 and the compression chamber 5. Then, the gas is discharged into the outlet chamber 25, and is discharged outside through the outlet 26. Owing to the 1st balance weight 22 and the 2nd balance weight 23, a centrifugal force of the orbiting scroll 1 is canceled. As such, vibration hardly occurs.
The lubricant oil 32 is fed from the oil tank 31 through the oil inlet tube 33, pressurized by the pump 34, and is dropped into the weight chamber 27 and the weight chamber 28 through the oil feed tube 35. The lubricant oil 32 is supplied to the 1st rotating shaft bearing 8, the 2nd rotating shaft bearing 10, the 1st orbiting bearing 12, the 2nd orbiting bearing 14, Oldham's keys 17A, 17A, and so forth, and returns from the bottom of the weight chamber 27 and the weight chamber 28 to the oil tank 31 through the oil return tube 36 after lubricating the curved portions and slide portions of these components.
According to an example of this embodiment, the 1st orbiting bearing 12 and the 2nd orbiting bearing 14 are not located at the center part of the orbiting scroll 1. Thus, the 1st orbiting bearing 12 and the 2nd orbiting bearing 14 are difficultly affected by the heat of the orbiting scroll 1 even when the orbiting scroll 1 is heated to a high temperature due to compression heat, thereby being less heated. That is, the durability of the compressor is increased. Further, since no bearing exists inside the orbiting shaft 1D, the distance between the outer periphery of the rotating shaft 6 and the inner periphery of the orbiting shaft 1D becomes small, thus the diameter of the orbiting shaft 1D can be made smaller. As such, the diameters of the orbiting scroll 1, the 1st fixed scroll 2 and the 2nd fixed scroll 3 can be made smaller, whereby the compressor can be made compact.
Further, since orbiting scroll 1 is located between the 1st orbiting bearing 12 and the 2nd orbiting bearing 14, a centrifugal force and gas load are equally applied to the 1st orbiting bearing 12 and the 2nd orbiting bearing 14. Thus, no tilt occurs for the orbiting scroll 1.
Further, the distance between the 1st orbiting bearing 12 and the 1st rotating shaft bearing 8 and the distance between the 2nd orbiting bearing 14 and the 2nd rotating shaft bearing 10 are small. Also, the distance between the 1st balance weight 22 and the 1st orbiting bearing 12 and the distance between the 2nd balance weight 23 and the 2nd orbiting bearing 14 are small. Thus, the moment applied to the rotating shaft 6 is small, thereby causing little deformation to the rotating shaft 6. As such, the orbiting scroll 1 can be stably operated with a set amount of eccentricity, even if the orbiting scroll 1 is driven at a high speed. Thus, little vibration occurs in the compressor.
In an example of this embodiment, a compressor is described. However, the present invention can be also applied to a scroll fluid machine such as a vacuum pump, a blower, an expander and so forth.
