Pressure-sealed Compressor

Abstract

A vane compressor has a rotor with radial vanes mounted in a housing cavity bounded by an endless actuator surface engaged by the outer ends of the vanes, and laterally bounded by two end walls having confronting stationary faces slidingly engaged by the rotor end faces to form clearance gaps. The end walls have conduits communicating with a high pressure container housing connected with the outlet of the housing, and opening in ports on the stationary housing faces, respectively, so as to fill and seal the gaps with high pressure fluid. The ports are longer in circumferential than in radial direction, and are located in an imaginary axial plane in which the vanes, which are completely inward pushed by the actuator surface, are located. Pressure ducts in the end walls are connected through an annular recess in the rotor shaft with an annular space in the rotor which is connected with the radially inner ends of the vane slots.

Description

BACKGROUND OF THE INVENTION

The present invention relates to rotary compressors, particularly vane compressors which have a rotor whose end faces form clearance gaps with lateral stationary faces.

The U.S. Pat. No. 2,654,532 discloses a rotary vane compressor in which high pressure oil from the output is used as sealing medium for the clearance gaps. The oil is supplied from the high pressure outlet along the rotor shaft to the end faces of the rotor where it is required for sealing. The actual amount of oil reaching the clearance gaps cannot be determined and may be irregular.

The arrangement of the prior art has the disadvantage that the oil used for sealing the clearance gaps of compressor is not used in the optimal manner, since oil is also supplied to parts of the compressor where the sealing is not necessary. In order to have a sufficient amount of oil available for a complete sealing where required, a comparatively large flow of oil along the rotor shaft is necessary in the prior art. It cannot be avoided that such large amounts of oil also flow in the expanding and contracting chambers formed by the vanes and by the actuator suface surrounding the same. The space in the contracting chambers is thus reduced, and a lesser amount of oil is pressed into the outlet, which reduces the efficiency of the compressor.

The U.S. Pat. No. 1,776,921 discloses a rotary vane compressor in which oil, under the outlet pressure of the compressor, is used as a sealing and lubricating medium. In this compressor, oil flows out of a high pressure container through a central bore in the rotor shaft to the radial slots in which the vanes are mounted for radial movement. The oil serves on the one hand for pressing the vanes against the endless actuator camming surface, and on the other hand seals and lubricates the vanes guided in the vane slots. The disadvantages explained above are present also in this compressor.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a compressor, particularly a vane compressor, in which the oil required for sealing the clearance gaps, is optimally used, so that only a minimum of oil is used for this purpose.

Another object of the invention is to supply fluid from the high pressure outlet of the compressor, to the clearance gaps between the rotor end faces and lateral stationary faces of the housing.

In accordance with the invention, the lateral end walls of the housing which have the stationary end faces, are provided with conduits, having one end communicating with high pressure outlet means, and another end formed as a port in the respective stationary face.

In the preferred embodiment of the invention, the ports in the lateral stationary faces are oblong and curved, and longer in circumferential direction than in radial direction. The distance between the radially outer edge of each port, and a circle on the stationary face having the diameter of the rotor, is between 2 and 5 mm.

It is particularly advantageous if two-thirds of the area of the port are located on the high pressure side, and one-third of the port is located on the low pressure side of an imaginary axial plane passing through the diametrically located rotor portions where the vanes assume their innermost position in the vane slots due to the action of the endless camming actuator surface on the outer ends of the vanes.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention, itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an axial sectional view taken on line I--I in FIG. 2; and

FIG. 2 is a cross sectional view taken along line II--II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The illustrated compressor has housing means which substantially include five parts, namely a left end wall 1 covered by a cover 17, an annular central housing part 3 having an inner ellipsoid camming actuator face 3c, a right end wall 2, and a container 23 secured to cover 17 by screws 17a and enveloping the end wall 2 and the central housing part 3.

Housing parts 1, 2 and 3 form a cavity 4 bounded by confronting stationary faces 1a and 2a of the end walls 1 and 2, and by the inner endless actuator surface 3c. Rotor means are provided which include a rotor 5 having end faces 5a and 5b, and a rotor drive shaft 6 which is secured to the bottom portion 5c of rotor 5 at one end, and has another end projecting out of the housing for being driven by a suitable motor. The outer cylindrical surface 5' of rotor 5 has a diameter which matches the length of the smaller axis of the ellipsoid inner endless actuator surface 3c so that a diametrical axial plane 29 is located between two crescentshaped portions of the cavity 4 located between the rotor surface 5' and the inner endless actuator surface 3c. The end wall 1 is integral with, or secured to, a tubular pintle 9 which projects inward into the cavity 4, and more particularly into a cylindrical bore in rotor 5. Rotor shaft 6 passes through the interior of tubular pintle 9 and has two journal portions 6b and 6c located in bearings 8 and 7 provided in the interior of the tubular pintle 9. Bearing 8 is located in a portion of the pintle 9 which projects outward from end wall 1. The shaft portion between journal portions 6b and 6c has an annular recess 6a communicating at one end through a bore and throttle 32 in the wall of pintle 9, with an annular space 31 communicating with the inner ends of the radial slots 12 in which vanes 13 are mounted for radial movement. The other end of recess 6a is connected by a duct 30 with liquid 27 in the lower portion of container 23.

A thrust bearing 11, preferably a needle bearing, is mounted between the inner free end of pintle 9 and a corresponding shoulder of the bottom portion 5c of rotor 5 to take up axial forces between the stationary pintle 9 and the rotor 5.

The radially outer ends of the vanes 13 abut the elipsoid inner endless camming surface 3c due to the pressure of the fluid supplied through the duct means 30, 6a, 32, 31 to the inner ends of the vanes 13.

The two crescent-shaped spaces between the rotor 5 and the inner endless actuator surface 3c are divided by diametrically disposed vanes 13 into expanding suction chambers 14b, and contracting pressure chambers 19c.

Suction chambers communicate through radial inlet passages 14, and axially extending bores 14a, with the inlet means 15 through an annular channel 16 in cover 17. Cover 17 has a tubular portion through which shaft 6 passes, sealed by sealing means 18.

The high pressure chambers 19c communicate through outlets 19 and leaf spring check valves 20 with axial pressure passages 21 provided with filter outlets 22 opening into the interior of the container 23 which has an outlet 25, protected by a baffle 24, and contains liquid 27 under high pressure.

As best seen for end wall 2, both end walls 1 and 2 are provided with conduits 26 whose lower ends communicate with the interior of high pressure container 23, and receive liquid therefrom. The lower portion of conduit 26 is covered in FIG. 1 by the duct 30, but the extension of conduit 26 in end wall 1 is the same as in end wall 2. A portion of conduit 26 is omitted in end wall 2 for the sake of clarity, and it will be understood that conduit 26 passes around the recess 2c in end wall 2, and passes around the inner bore of the tubular pintle 9 in end wall 1.

The upper ends of the two conduits 26 in end walls 1 and 2 are provided with ports 28 which open on the confronting inner stationary faces 2a and 1a of end members 2 and 1. Each port 28 is arcuate and oblong in circumferential direction, so that the circumferential extension of each port 18 is greater than its radial dimension. The radially outer edge or boundary 28' of each port 28 and the outer rotor surface 5' is between 2 and 5 mm., and preferably 4 mm.

Two-thirds of the area of each port 28 are located on the high pressure side of an imaginary diametrical axial plane 29, and one-third on the low pressure side of plane 29 which passes through the rotor axis, and through the generatrix of the cylindrical outer rotor surface 5' where the vanes 13 are in the innermost positions in slots 12. In other words, two-thirds of the area of port 28 is located on the side of plane 29 facing the outlets 19, and one-third of the area of port 28 is located on the side of plane 29 facing the inlets 14.

During rotation of rotor 5 in clockwise direction, the outer edges of vanes 13 slide along the endless elipsoid inner camming actuator surface 3c so that chambers 14b expand and suck the fluid to be compressed from the inlet openings 14, axial conduits 14a, annular space 16 and inlet 15. During further rotation, the spaces 19c contract so that the compressed fluid is discharged through the leaf spring check valves 20 into the outlet passages 21 and through the filters 22 into the high pressure container 23 from where the fluid is discharged through outlet 25.

Immediately after the compressor has started working, and rotor shaft 6 with rotor 5 is driven, the interior of the housing container 23 is subjected to high pressure.

The stored oil 27 is pressed into the conduits 26 in the end walls 1 and 2 and into the duct 30 in end wall 1. Liquid under pressure flows out of the ports 28 in the confronting stationary faces 1a and 2a of the end walls 1 and 2, and is pressed into the clearance gaps between stationary faces 1a and 2a and rotating rotor end faces 5a and 5b.

It has been found by tests that in the region where the ports 28 are located, and where the greatest pressure differentials occur within the respective clearance gaps are safely sealed by the oil pressed into the clearance gaps through the ports 28.

Oil is also pressed out of pressure container 23 into the duct 30 from where it flows through the recess 6a in rotor 6, the throttle 32, and annular connecting space 31 into the inner ends of the vane slots 12 so that the vanes 13 are pressed radially outward into engagement of their outer ends with the endless inner camming actuator surface 3c, sealing the expanding suction chambers 14b from the contracting pressure chambers 19b. At the same time, the oil in shaft recess 6a, lubricates the bearings 7 and 8 of the rotor shaft 6. The elipsoid shape of the actuator surface 3c of the central housing wall 3 which exerts a cam action on the vanes 13, is geometrically designed so that the radial stroke of two diametrically arranged vanes 13 in outward and inward direction, corresponds in every position of rotor 5 to an exactly equal length of the strokes in inward and outward directions of the two vanes 13 which are angularly displaced 90.degree. in relation to the first two vanes 13. This has the result that the volume of liquid in the common annular space 31 is constant in every position of rotor 5 with vanes 13.

The quantity of oil leaking out of the clearance gaps 1a, 5a and 2a, 5b and between the outer ends of vanes 13 and the actuator surface 3c, is replenished through throttle 32, which may be omitted under certain circumstances, and by throttled flow along the bearing 7 whose play permits a throttled flow. The oil volume in the annular space 31 and in the inner parts of vane slots 12 serves as damping oil for the vanes 13 and prevents chatter of vanes 13, which frequently occurs in vane compressors of the prior art.

The ellipsoid inner actuator surface 3c, which is suitable for a two-flow compressor, may be replaced with a circular inner actuator surface having an axis eccentric to the rotor axis so that the compressor is a single-flow compressor.

It is also possible to provide the elipsoid endless inner actuator surface 3c with a circular portion parallel to the outer cylindrical surface of the rotor so that the sealing between the rotor 5 and the respective portions of the inner endless actuator surface 3c is improved. In such an arrangement, the imaginary plane 29, which determines the position of the ports 28, passes through the rotor axis and the generatrix of the outer rotor surface, which is located in the center of the regions where the outer surface of the rotor and the circular portions of the inner surface 3c are parallel.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of pressure-sealed compressors differing from the type described above.

While the invention has been illustrated and described as embodied in a pressure-sealed compressor in which the clearance gaps at the ends of the rotor are provided with high pressure oil through conduits and ports in the end members of the housing, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

We claim:

1. Pressure-sealed compressor comprising housing means including a central housing part having a cylindrical cavity surrounded by an endless inner actuator surface, a pair of end walls closing the ends of said cavity and having confronting stationary faces, a tubular pintle on one of said end walls, and inlet and outlet means for a fluid, said housing means further including a container for high pressure fluid communicating with said outlet means and having an outlet for high pressure fluid; rotor means mounted on said housing means for rotation about an axis, and including a rotor having rotor end faces slidingly engaging said stationary faces and forming clearing gaps therewith, a drive shaft portion mounted in said tubular pintle for rotation and including a thin shaft portion formed with an annular recess, and a plurality of vanes respectively mounted in radial slots of said rotor and having outer ends slidingly engaging said actuator surface for forming expanding and contracting chambers between said rotor and said actuator surface, said inlet and outlet means communicating with said chambers, said rotor being formed with an annular space surrounding said pintle and connecting radially inner ends of said slots; said housing means being formed with duct means connecting said outlet means and said annular space so that high pressure in said slots urges said vanes into engagement with said actuator surface, said annular recess forming part of said duct means and communicating with said annular space; and at least one of said end walls being formed with a conduit having one end connected with said outlet means and the other end formed as a port in said stationary face of said end wall opening into the respective gap between the respective stationary face and rotor end face so that fluid is pressed into said gap for sealing the same against leakage.

2. Compressor as claimed in claim 1, wherein the other end wall is formed with a conduit having one end communicating with said container and the other end forming a port in the respective stationary face of said other end wall opening into the respective other gap between the other stationary face and the other rotor end face so that the same axial pressure acts at opposite ends of said rotor.

3. Pressure-sealed compressor comprising housing means including a central housing part forming a cylindrical cavity surrounded by an endless inner actuator surface, a pair of end walls closing the ends of said cavity and having confronting stationary faces, and inlet means and outlet means for a fluid; rotor means mounted in said housing means for rotation about an axis, and including a rotor having rotor end faces slidingly engaging said stationary faces and forming clearance gaps therewith, and at least one vane mounted in a radial slot of said rotor and having an outer end slidingly engaging said actuator surface for forming expanding and contracting chambers between said rotor and said actuator surface, said inlet means and outlet means on said housing means communicating with said expanding and contracting chambers, respectively; and each of said end walls being formed with a conduit having one end connected with said outlet means and the other end formed as a port in the respective stationary face of the respective end wall opening into the respective gap between the respective stationary face and rotor end face so that fluid is pressed into both gaps for sealing the same against leakage, each of said ports being longer in circumferential direction than in radial direction.

4. Compressor as claimed in claim 3, wherein said rotor means include four vanes forming in said cavity between said rotor and said actuator surface two expanding suction chambers and two contracting pressure chambers alternating with said suction chambers; wherein said actuator surface places diametrically disposed vanes simultaneously in innermost positions when passing through an imaginary axial plane whereby on one side of said imaginary plane high pressure, and on the other side of said plane low pressure prevails in said cavity; and wherein said ports are located in said imaginary axial plane and have port portions located on opposite sides of said imaginary axial plane.

5. Compressor as claimed in claim 4, wherein the radial outer boundary of said port is spaced from the outer surface of said rotor a radial distance between 2 and 5 millimeters.

6. compressor as claimed in claim 4, wherein the port portion located on said one high pressure side of said imaginary plane is longer in circumferential direction than the port portion located on the other low pressure side of said imaginary plane.

7. Compressor as claimed in claim 6, wherein two-thirds of the area of said port are located on said high pressure side and one-third of the area is located on said low pressure side of said imaginary plane.

8. Compressor as claimed in claim 3, wherein said rotor is formed with an annular space connecting the radially inner ends of said radial slots; and wherein said housing means are formed with duct means connecting said outlet means with said annular space so that high pressure in said slots urges said vanes into engagement with said actuator surface.

9. Compressor as claimed in claim 8, wherein said duct means include a throttle upstream of said annular space.

10. Compressor as claimed in claim 8, wherein said housing means include a container for high pressure fluid communicating with said outlet means and having an outlet for high pressure fluid; wherein said conduit has said one end communicating with said container; and wherein said duct means communicates with said container.