Rotating Scroll Machine With Oil Pump

The present invention relates to a scroll machine of a full rotation type in which both a driving scroll and a driven scroll are rotated.

FIG. 5 is a cross section of a conventional scroll machine such as disclosed in Japanese Kokai No. 87693/1987, in which a reference numeral 1 depicts a casing, 2 a flange arranged in the casing 1 and having vertical oil return holes 2a and 3 a bearing support fixedly secured to the flange 2 and having a central, cylindrical boss portion 3a. A reference numeral 4 depicts a motor having a motor shaft 4a whose upper end is rotatably supported within the boss portion 3a. An eccentric hole 4b is formed in the upper end of the motor shaft 4a and an oil supply path 4c formed in the shaft 4a extends therealong to establish a communication from the eccentric hole 4b to the lower end of the shaft 4a. A reference numeral 5 depicts a driving scroll having a shaft 5a inserted into the eccentric hole 4b, 6 a stationary scroll coupled to the bearing support 3 to form, together with the driving scroll 5, a compression chamber 7, 8 a trochoid pump arranged between a lower surface 4d of the eccentric hole 4b and a lower end 5b of the shaft portion 5a and coupled to the latter. The trochoid pump has a suction port 4e formed in the bottom 4d of the eccentric hole 4b and a discharge port 5c formed in the lower end 5b of the shaft portion 5a. A reference numeral 9 depicts lubricant oil reserved in a bottom portion of the casing 1 in which the lower end of the motor shaft 4a is immersed A known anti-rotation mechanism 10 is provided for preventing rotation of the driving scroll 5. Reference numerals 13 and 15 depict a discharge port for discharging gas from the casing 1 and a suction port communicated with a space between the scrolls 5 and 6, respectively.

In operation, when the motor shaft 4a rotates, the driving scroll 5 orbits with respect to the stationary scroll 6, so that gas is taken in from the suction port 15, compressed by means of the relative movement of the stationary scroll 6 to the driving scroll and discharged through the discharge port 13 outside of the casing 1. With the rotation of the motor shaft 4a having the eccentric hole 4b in which the shaft portion 5a of the driving scroll 5 is received, the shaft portion 5a tends to rotate eccentrically together with the driving scroll 5. However, due to the presence of the anti-rotation mechanism 10 provided between the driving scroll 5 and the bearing support 3, the shaft portion 5a orbits. Therefore, the trochoid pump 8 disposed between the shaft portion 5a and the bottom 4d of the eccentric hole 4b performs a pump operation with an aid of an inner surface of the eccentric hole 4b, so that oil 9 is sent from the oil supply path 4c through the suction port 4e and the trochoid pump 8 to the discharge port 5c to lubricate sliding portions such as an outer periphery of the shaft portion 5a and the lower surface of the driving scroll 5 and, then returned through the oil return hole 2a to the bottom portion of the casing 1.

That is, in the conventional scroll machine, the oil pump portion is arranged at the upper end of the motor shaft and oil in the bottom portion of the casing has to be sucked up through the oil supply path formed in the motor shaft. Therefore, the length of the oil supply path becomes large, necessarily, causing fluid resistance in the suction side of pump to be large and the size of pump to become large.

The present invention is intended to solve the above mentioned problems and an object thereof is to provide a scroll machine whose sliding portions can be lubricated reliably with a pump of small capacity.

In order to achieve the above object, a scroll machine according to the present invention comprises a pair of scrolls capable of rotating on different axes to form a compression chamber therebetween and discharging compressed gas in the compression chamber to a discharge chamber, a pair of boss portions immersed in lubricant oil for rotatably supporting the respective scrolls through bearing means, a first oil supply path formed in one of the boss portions for communication with a bearing receiving recess of the one boss portion, a second oil supply path formed in one of the scrolls on the side of the one boss portion for communication of the first oil supply path with the compression chamber through the recess and a pump coupled to a shaft portion of the one scroll for supporting it rotatably within said bearing boss portions and for supplying oil in the discharge chamber to the first oil supply path.

In the scroll machine according to the present invention, oil around the boss portion is taken in directly by the rotary pump and supplied by the latter to the bearing portions and to the compression chamber within the scrolls. Therefore, the sliding portions of the machine can be lubricated reliably with the pump whose capacity is small enough.

FIG. 1 is a cross sectional side view of an embodiment of the present invention;

FIG. 2 is a cross section of a main portion of the present invention;

FIG. 3 is a cross section taken along a line III--III in FIG. 2;

FIG. 4 is a cross section of a main portion of another embodiment the present invention; and

FIG. 5 is a cross section of a conventional scroll machine.

FIGS. 1 to 3 show an embodiment of the present invention in cross section. In these figures a rotary shaft 11a of a motor 11 fixedly mounted on an upper casing 12 which defines a discharge chamber B therein protrudes downward into the latter. The upper casing 12 is provided on one side of an upper portion thereof with a discharge port 13 and on the opposite side with a suction port 15 connected to a vacuum vessel 14.

A vertical suction passage 12a is provided in the upper casing 12. The suction passage 12a is isolated from an interior of the upper casing 12 and has an upper end connected to the suction port 15 and a lower end opened.

A lower casing 16 is connected to the lower end of the upper casing 12. The lower casing 16 has at an upper end thereof a bearing support 16a having a boss portion 16b in which an oil supply path 16c communicating with an interior of a bearing receiving portion 16d is formed. A lower cover 17 connected to a lower portion of the lower casing 16 is provided.

A driving scroll 18 is arranged within the lower casing 16. The driving scroll 18 has a shaft portion 18a protruding upwardly beyond the upper casing 12 and is supported rotatably through bearings 20 and 23 supported by the lower casing 16 and the upper casing 12, respectively.

An oil supply path 18b is formed along the shaft portion 18a, which communicates the interior of the bearing receiving portion 16d with a compression chamber A to be described.

A driven scroll 21 forms, together with the driving scroll 18, the compression chamber A. A shaft portion 21a of the driven scroll 21 is rotatably supported by bearings 22 supported by the lower cover 17 at a position eccentric with respect to the axis of the driving scroll 18.

An Oldham coupling 24 couples the driving scroll 18 to the driven scroll 21 such that they are rotatable with respect to each other. The Oldham coupling 24 is composed of an arm 24a coupled to the driving scroll 18 and a coupling 24b coupled to the driven scroll 21. A coupling 25 couples the rotary shaft 11a to the shaft portion 18a and is integral with a cooling fan 25a.

A sealing between the upper casing 12 and the lower casing 16 is provided by an O-ring 26 and a sealing between the suction passage 12a and the interior of the upper casing 12 is provided by an O-ring 27. An O-ring 28 is provided between the lower casing 16 and the lower cover 17.

A discharge path 29 is formed in the shaft portion 18a and has an upper opening positioned above an oil level 30.

Reference numerals 31 and 32 depict oil-seals for sealing between the upper casing 12 and the lower casing 16. A vane pump 33 is coupled to the bearing support 16a. The vane pump 33 is composed of a pump casing 33b having an oil supply path 33a connected to the oil supply path 16c, a rotor 33c fixed on the shaft portion 18a, a vane 33d fixed on the rotor 33c, a suction port 33e formed in the pump casing 33b, a discharge port 33f for oil, a pump cover 33g covering the pump casing 33b, a normally closed relief valve 33h for ON-OFF controlling the discharge port 33f and the oil supply port 33a, a biasing spring 33j for biasing the relief valve 33h and an O-ring 33k for sealing between the pump casing 33b and the boss portion 16b.

In operation, with rotation of the motor 11, the driving scroll 18 rotates, by which the driven scroll 21 is rotated eccentrically through the Oldham coupling 24. Therefore, gas is compressed between the scrolls 18 and 21 and discharged through the discharge path 29 into the upper casing 12. Consequently, gas in the vacuum vessel 14 is taken in the compression chamber between the scrolls 18 and 21 through the suction port 15, the suction path 12a and the lower casing 16 and, after being compressed, is discharged into the upper casing 12, similarly. Compressed gas within the upper casing 12 is discharged through the discharge port 13.

Lubrication oil within the lower casing 16 is taken in the chamber between the scrolls 18 and 21 to seal mutual sliding surfaces of them to each other to thereby prevent gas from leaking, and a portion of the lubricant is discharged, together with gas, through the discharge path 29 into the upper casing 12. Therefore, the amount of oil within the lower casing 16 is reduced gradually, resulting in degradation of gas sealing. In order to solve this problem, the vane pump 33 is provided. The vane pump 33 supplies oil in the upper casing 12 to the respective scrolls 18 and 21. That is, when the rotor 33c mounted on the shaft portion 18a of the driving scroll 18 rotates, oil existing around the suction port 33e is taken by the vane 33d and the pump casing 33b and discharged through the discharge port 33f. When the discharge pressure of the oil at the output of the discharge port 33freaches a sufficient level, the relief valve 33h is raised against the spring 33j, so that the discharge port 33 f is communicated with the oil supply path 33a. Therefore, oil is supplied through the oil supply path 33a and the oil supply path 16c to the bearing support recess 16d (see FIG. 2) and then to the compression chamber A between the scrolls 18 and 21 through the oil supply path 18b. Thus, a certain amount of oil is always kept reserved on the respective scrolls 18 and 21, so that gas leakage between the sliding surfaces of the scrolls is reliably prevented.

When the motor 11 stops rotating, there is no discharge pressure of the vane pump 33, so that the relief valve 33h is closed by the spring to prevent a reverse gas flow through the oil supply path 33a, 16c and 18b.

FIG. 4 shows another embodiment of the present invention. In FIG. 4, the scroll machine includes a bearing journal 17a formed in a boss portion 17b of a lower cover 17. A pair of oil seals 34 are fitted on the bearing journal 17a, a horizontal oil supply path 35 is formed in the lower cover 17 and communicates with the bearing journal 17a, a vertical oil supply path 36 communicates with the oil supply path 35, a vertical oil supply path 37 formed in the lower casing 16, a horizontal oil supply path 38 communicates with the oil supply path 37, a plug 39 closes an opening of the oil supply path 38, nut 41 is provided on a shaft portion 21a of the driven scroll 21 for positioning the bearings 22, a vane pump 42 is coupled to a lower end of the shaft portion 21a, a vane 42b is fitted on a rotor 42a thereof, a pump casing 42c covers them, and a pump cover 42d is disposed between the pump casing 42c and the lower cover 17.

The pump cover 42d is provided with a suction port 42e communicating with an interior of the bearing journal 17a, a discharge port 42f, a horizontal oil supply path 42g communicating with the discharge port 42f, a vertical oil supply path 42h communicating with the oil supply path 42g, and a plug 42j closing an opening of the oil path 42g.

An oil path 43 is formed in the lower cover 17 for communication between the oil supply path 42h and the bearing journal 17a. The shaft portion 21a includes an oil path 44 extending longitudinally thereof to communicate with the oil path 43 through the bearing journal 17a, and a vertical oil path 45 for communicating the oil path 44 with the compression chamber A between the scrolls 18 and 21. A relief valve 46 ON-OFF controls a communication between the oil path 42h and the oil path 43, a spring 47 biases the relief valve 46, an O-ring 48 seals the oil path 37, an O-ring 49 seals the oil path 42h, and a pair of O-rings 50 seal the upper and lower ends of the pump cover 42d, respectively.

In this embodiment, oil is taken by the vane pump 42 through the oil paths 38, 37, 36 and 35, the bearing journal 17a and the suction port 42e and discharged from the discharge port 42f. The same oil is discharged through the oil paths 42g, 42h and 43 to the bearing journal 17a and, then, through the oil paths 44 and 45 to the compression chamber A between the scrolls 18 and 21.

Then, when the motor 11 stops rotating and, thus, the vane pump 42 is stopped, the relief valve 46 is closed by the spring 47 to prevent air from entering into the compression chamber A.

The vane pump 42 used in both embodiments may be replaced by any other pump such as a trochoid pump

As mentioned hereinbefore, according to the present invention, a scroll machine comprises a pair of scrolls capable of rotating on different axes to form a compression chamber therebetween and discharging compressed gas in the compression chamber to a discharge chamber, a pair of boss portions immersed in lubricant oil for rotatably supporting the respective scrolls through bearing means, a first oil supply path formed in one of the boss portions for communiation with a bearing receiving recess of the one boss portion, a second oil supply path formed in one of the scrolls on the side of the one boss portion for communication of the first oil supply path with the compression chamber through said recess and a pump coupled to a shaft portion of the one scroll for supporting it rotatably within said bearing boss portions and for supplying oil in the discharge chamber to the first oil supply path. Therefore, the sliding portions of the machine can be lubricated reliably for a considerably long time with the pump whose capacity is small enough.