Passage arrangement for cooling, lubricating and reducing the size of rotary machines

Abstract

A fluid-moving rotary device that has a drive mechanism whose rotational axis is aligned with a rotational axis of a driven component and another component that rotates about an axis offset from rotational axis of the driven component. The drive mechanism is located on a fluid inlet side of the components and is cooled by the fluid entering the device.

Claims

1. A rotary device, comprising: a housing, a first component rotatable about a first axis within the housing, a second component within the housing and configured to rotate about a second axis offset from the first axis and relative to the first component; and a drive mechanism within the housing and having a shaft whose rotational axis is aligned with the first axis of the first component, with one end of the shaft of the drive mechanism being operatively connected with the first component for driving the first component and another end of the drive mechanism being supported by a bearing arrangement, wherein passages are grouped together and contained in an offset portion of the housing that only partially surrounds the rotational axis for allowing a main fluid to flow through the rotary device.

2. The rotary device of claim 1, wherein the first and second components have a fluid inlet side, and the drive mechanism is located on the fluid inlet side of the first and second components and is cooled by the main fluid entering the rotary device through the passages.

3. The rotary device of claim 2, wherein the main passages are configured to be of different areas.

4. The rotary device of claim 3, wherein the drive mechanism includes a gap forming a cooling passageway and being operatively connected with the passages to provide cooling of the first and second components.

5. The rotary device of claim 1, wherein the passages are arranged at the fluid inlet side and are configured to transport lubricating fluid entrained in the main fluid with a velocity sufficient to carry the entrained lubricating fluid to the first and second components.

6. The rotary device of claim 1, wherein the first and second components are screws comprising a screw compressor.

7. The rotary device of claim 1, wherein the bearing arrangement has at least one outer race and associated rolling elements to which lubricant is supplied through a port to a radial groove around at least one portion of one bearing outer race and a plurality of face grooves aligned with a face of the at least one bearing outer race to admit lubricant from outside the at least one outer race to the rolling elements.

8. The rotary device of claim 1, wherein the passages are formed between the housing and the drive mechanism.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings herein.

(2) FIG. 1 is an elevational view of a screw compressor of generally known construction that uses the principles on my invention.

(3) FIG. 2 is a cross-sectional plan view of the two-screw compressor of FIG. 1 but with a direct drive motor, bearing lubrication, and main fluid passages according to my invention taken along line A-A of FIG. 1.

(4) FIG. 3 is a cross-sectional plan view of the two-screw compressor with a direct drive motor, bearing lubrication, and main fluid passages according to my invention taken along line B-B of FIG. 1.

(5) FIG. 4 is an enlarged isolated view showing details the motor shaft bearing and lubrication passages shown in FIG. 2, it being understood that the bearings are arranged cylindrically around a shaft in a known manner.

(6) FIG. 5 is an isometric view of one motor shaft bearing used in the arrangement of FIG. 4 in accordance with my invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) Referring now to FIGS. 1 and 2, a housing 101 of a screw compressor, generally designated by numeral 100, houses a two-screw compressor comprised of a screw 103 directly driven by a motor 110 and a mating screw 102, where the screw 102 is offset from the motor centerline to mesh with screw 103 in a generally known manner. Housing 101 is therefore disproportioned about centerlines of a motor shaft 104 and the screw 103 to also enclose the screw 102. In one compact package embodiment of the screw compressor 100 of my invention as seen along the rotational axis, fluid transfer ports 106a, 106b, and 106c are positioned to occupy the region set by the offset in housing 101 required to enclose the screw 102.

(8) FIG. 3 shows an embodiment of my invention where the main fluid transfer port 106a is sized to encompass the offset in housing 101 required to enclose compressor screw 102.

(9) FIGS. 4 and 5 show a bearing arrangement according to my invention where pressurized liquid lubricant (such as POE for an R-134a refrigeration system compressor) is fed through a port 109 to an annular groove 108. Two bearings 107 are mounted back-to-back in the housing 105 for loading in radial and both axial directions. In this embodiment, adjoining faces with lubricant passages 112 as shown in FIG. 5 are arranged face-to-face and align with the housing groove 108. Lubricant enters bearing rolling elements 113 through the passages 112. Lubrication and cooling of the bearings occur, then the lubricant is expelled into the series of the main fluid transfer ports 106a, 106b, 106c in the housing 105 as described above.

(10) The total cross sectional area of the main fluid passage 106a in combination with the ports 106b, and 106c shown in FIG. 3 are sized to operate at a flow velocity to entrain the lubricant expelled from the bearings 107 in the main fluid and transport that entrained lubricant to the compressor screws with the main fluid. As will now be apparent to one skilled in the art, the area will vary according to different compressor configurations, applications and the like, and can be readily determined through routine experimentation.

(11) The passages 106a, 106b, and 106c also enable the components of the motor 110 to be cooled with the main fluid. This requires sufficient surface area adjacent to the motor components to thermally transfer motor heat from the motor components 110, through the housing 105, and into the main fluid. In a refrigeration compressor this thermal event ensures that the main fluid, such as R-134a, is in a superheated state after it passes the motor. I have found that the passages 106a, 106b, and 106c do not need to surround all of the motor components 110 for sufficient cooling, with the housing 105 being configured to transfer heat to the compressor surroundings and conductively transfer that heat to the passages 106a, 106b, and 106c to achieve a more compact overall compressor package. In one embodiment, the gap between motor components 110 and 111 will act as a main fluid passage for cooling.

(12) Although I have described my invention specifically with regard to hermetic screw-type compressors used in refrigeration systems, it is to be understood that my invention is not limited to those specific systems. I intend to cover all related devices as are encompassed by the claims and not just the details disclosed and described herein.