ES2909572T3 - Lubricant supply passage for compressors - Google Patents

Abstract

fluid machine (20) comprising: a housing (36); a first rotor (22) fixed to a first shaft (34), the first rotor and the first shaft being rotatable about a first axis, wherein the first shaft is rotatably supported on the casing; a second rotor (24) is supported by a second shaft (50), the second rotor being able to rotate about a second axis, in which the second rotor is configured to rotate about the second shaft and in which the second shaft is supported on the casing and is fixed relative to it; a manifold (61) containing a volume of lubricant therein; a first lubricant passageway for supplying manifold lubricant to a dynamic interface associated with the first rotor; and a second lubricant passageway for supplying manifold lubricant to a dynamic interface associated with the second rotor; wherein a differential pressure created within the fluid machine supplies the lubricant from the manifold to the first lubricant passage and the second lubricant passage simultaneously.

Description

DESCRIPTION

Lubricant supply passage for compressors

Background

The subject matter described in this document relates generally to fluid machines and, more specifically, to fluid machines such as compressors.

Commonly used refrigerants, such as R-410A in a non-limiting example, have been found to have unacceptable Global Warming Potential (GWP) such that they will be discontinued for many HVAC&R applications. Low GWP non-flammable refrigerants are replacing existing refrigerants in many applications, although they have a lower density and do not possess the same cooling capacity as existing refrigerants. Replacement refrigerants require a compressor capable of providing significantly higher displacement, such as a screw compressor.

Existing screw compressors typically used roller, ball, or other roller bearings to accurately position the rotors and minimize friction during high-speed operation. However, for typical HVAC&R applications, existing screw compressors with roller bearings result in an unacceptably large and expensive fluid machine.

US 3922114 A, US 3811805 A, US 2013/058822 A1, US 2016/097572 A1, US 4211522 A and US 5662 463 A disclose known fluid machines.

Therefore, there is a need in the art for an appropriately sized, cost effective fluid machine that minimizes friction while allowing for precise positioning and alignment of the rotors.

In a first aspect, a fluid machine is provided including a housing; a first rotor fixed to a first shaft, the first rotor and the first shaft being rotatable about a first axis, wherein the first shaft is rotatably supported on the casing; a second rotor is supported on the second shaft, the second rotor being rotatable about a second axis, wherein the second rotor is configured to rotate about the second shaft and wherein the second shaft is supported on the housing and fixed regarding her; a manifold containing a volume of lubricant therein, a first lubricant passage for supplying manifold lubricant to a dynamic interface associated with the first rotor, and a second lubricant passage for supplying manifold lubricant to a dynamic interface associated with the first rotor. second rotor. A differential pressure created within the fluid machine supplies lubricant from the manifold to the first lubricant passage and the second lubricant passage simultaneously.

Optionally, during operation of the fluid machine, differential pressure builds up between a high pressure adjacent to at least one end of the housing and a low pressure at a central location of the first rotor and the second rotor.

Optionally, the first rotor and the first shaft are rotatably mounted in the housing without roller bearings.

Optionally, wherein at least one surface of the casing and the first shaft define the dynamic interface associated with the first rotor.

Optionally, the at least one housing surface arranged in direct contact with the first shaft functions as a bearing.

Optionally, the at least one housing surface disposed in direct contact with the first shaft includes a first surface disposed in direct contact with a portion of the first shaft adjacent a first end, and a second surface disposed in direct contact with a portion of the first shaft. first tree adjacent to a second endpoint.

Optionally, the first lubricant passageway includes a first part for supplying lubricant to the first surface and a second part, other than the first part, for supplying lubricant to the second surface.

Optionally, the first lubricant passage further comprises: a cavity formed in a portion of the casing adjacent the first shaft, a passage extending axially through at least a portion of the first shaft, at least one radial hole engaging the cavity and the passage, and a slot extending from the cavity to an interior of a compression pocket formed between the first rotor and the second rotor and the casing.

Optionally, the first lubricant passage further comprises: a counterbore formed at the interface between the casing and the compression pocket.

Optionally, the first lubricant passage comprises: a slot extending from the manifold to an interior of a compression pocket formed between the first and second rotors and the casing.

Optionally, the second rotor comprises a working part rotatable with respect to the second shaft. The second tree and the working part define the dynamic interface associated with the second rotor.

Optionally, the second lubricant passage further comprises: a first passage extending axially through at least a portion of the second shaft, a second passage formed on an outer periphery of the second shaft, and at least one radial hole engaging the first step and the second step.

Optionally, the second passage extends axially such that a first end of the second passage fluidly engages a first housing part and an opposite second end of the second passage fluidly engages a second housing part.

Optionally, a counterbore is formed in the housing where at least one of the first lubricant passage and the second lubricant passage enters a compression pocket formed between the first rotor and the second rotor.

Optionally, the fluid machine comprises a recess formed in the housing in fluid communication with the counterbore, the recess being angled toward an interface between the first rotor and the second rotor.

Optionally, at least one of a recess angle, length, width and depth is optimized to control a flow of lubricant into the compression pocket.

In a second aspect, a method of lubricating one or more dynamic interfaces of a fluid machine is provided, the fluid machine comprising a housing. The method includes supplying lubricant from a manifold to a dynamic interface associated with a first rotor attached to a first shaft of the fluid machine through a first lubricant passageway, wherein the first rotor and first shaft are rotatable about a first shaft, and in which the first shaft is rotatably supported in the housing; and supplying lubricant from a manifold to a dynamic interface associated with a second rotor bearing on a second shaft of the fluid machine through a second lubricant passage, wherein the second rotor is rotatable about a second axis , in which the second rotor is configured to rotate about the second shaft and in which the second shaft is supported by and fixed with respect to the casing. The second lubricant step is different from the first lubricant step. The supply of lubricant to the dynamic interface associated with the first rotor and the dynamic interface associated with the second rotor occurs automatically and simultaneously in response to a differential pressure created within the fluid machine during operation of the fluid machine. .

Optionally, the supply of lubricant from the manifold to the dynamic interface associated with the first rotor and the supply of lubricant from the manifold to the dynamic interface associated with the second rotor occurs without a pump or control valve.

Optionally, supplying lubricant from the manifold to the dynamic interface associated with the first rotor further comprises: supplying lubricant through a first passage to a first bearing surface, the first passage extending through an opening formed in the first shaft of the first rotor, and supplying lubricant through a second passage to a second bearing surface.

Optionally, supply lubricant from the dynamic interface associated with the first rotor and the dynamic interface associated with the second rotor to a compression pocket formed between the first rotor and the second rotor.

Brief description of the drawings

The subject matter, which is considered to be the invention, is particularly pointed out and clearly claimed in the claims at the end of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description, which describes embodiments of the invention by way of example only, taken in conjunction with the accompanying drawings in which:

Figure 1 is a cross-sectional view of a fluid machine;

Figure 2 is a perspective view of a working part of a fluid machine;

Figure 3 is a cross-sectional view of a fluid machine including a lubricant supply passageway;

Figure 4 is a cross-sectional view of a working part of a fluid machine;

Figure 5 is a perspective cross-sectional view of a fluid machine housing; Figure 6 is a perspective view of a second shaft of a fluid machine; Y

Figure 7 is a front view of a bearing housing surface facing a compression pocket of the fluid machine.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example only and with reference to the drawings.

Detailed description

Referring now to Figures 1 and 2, a fluid engine 20 is illustrated. In the illustrated non-limiting embodiment, the fluid engine 20 is an opposed screw compressor. However, other suitable embodiments of a fluid machine, such as, for example, a pump, a fluid motor, or a motor, are also within the scope of the invention. The fluid machine 20 includes a first rotor 22 in mesh with a second rotor 24. In one embodiment, the first rotor 22 is a male rotor having a working portion 26 with male lobes and the second rotor 24 is a female rotor including a part 28 with female lobes. On the other hand, the first rotor 22 may be a female rotor and the second rotor 24 may be a male rotor. Working portion 26 of first rotor 22 includes at least one first helical lobe 30 and at least one second helical lobe 32. In the illustrated non-limiting embodiment, first rotor 22 includes two separate portions defining first helical lobes 30 and second helical lobes. second helical lobes 32. In another embodiment, the first rotor 22, including the first and second helical lobes 30, 32, may be formed as a single integral piece.

Fluid machine 20 includes a first shaft 34 fixed to rotate with first rotor 22. Fluid machine 20 further includes a housing 36 rotatably abutting first shaft 34 and at least partially enclosing first rotor 22. and second rotor 24. A first end 38 and a second end 40 of casing 36 are configured to rotatably abut first shaft 34. In the illustrated non-limiting embodiment, lower first end 38 of casing 36 is formed by a lower bearing housing 42 and the second upper end 40 of the housing 36 is formed by a separate upper bearing housing 44. A rotor housing 46 may extend between and engage the upper and lower bearing housings 42, 44. However, embodiments in which the lower bearing housing 42 and/or the upper bearing housing 44 are integrally formed with the rotor housing 46 are also contemplated herein.

The first shaft 34 of the illustrated embodiments is directly coupled to an electric motor 48 which serves to drive rotation of the first shaft 34 about an axis X. Any suitable type of electric motor 48 is contemplated herein, including but not limited to for example, an induction motor, a permanent magnet (PM) motor, and a switched reluctance motor. In one embodiment, the first rotor 22 is attached to the first shaft 34 by a clamp, a coupling, an integral formation, an interference fit, and/or any additional structure or method known to one skilled in the art (not shown). , so that the first rotor 22 and the first shaft 34 rotate about the axis X in unison.

The fluid machine 20 further includes a second shaft 50 which serves to rotatably support the second rotor 24. The second rotor 24 includes an axially extending bore 52 within which the second shaft 50 is received. In one embodiment , the second shaft 50 is stationary or fixed with respect to the housing 36 and the second rotor 24 is configured to rotate about the second shaft 50. However, embodiments in which the second shaft 50 can also rotate with respect to the second shaft 50 are also contemplated here. to casing 36.

With particular reference to Figure 2, the first rotor 22 is shown including four first helical lobes 30 and at least four second helical lobes 32. The illustrated non-limiting embodiment is intended to be an example only and one of ordinary skill in the art should to understand that any suitable number of first helical lobes 30 and second helical lobes 32 is within the scope of the invention. As shown, the first helical lobes 30 and the second helical lobes 32 have opposing helical configurations. In the illustrated non-limiting embodiment, the first helical lobes 30 are on the left and the second helical lobes 32 are on the right. Alternatively, the first helical lobes 30 may be on the right and the second helical lobes 32 may be on the left.

By including lobes 30, 32 with opposing helical configurations, opposing axial flows are created between the first and second helical lobes 30, 32. Due to the symmetry of the axial flows, the thrust forces resulting from the helical lobes 30, 32 are generally equal and opposite, so that the buoyant forces substantially cancel each other. As a result, this configuration of the opposed helical lobes 30, 32 provides a design advantage in that the need for thrust bearings in the fluid engine can be reduced or eliminated.

The second rotor 24 has a first portion 54 configured to engage with the first helical lobes 30 and a second portion 56 configured to engage with the second helical lobes 32. To achieve a proper meshing engagement between the first rotor 22 and the second rotor 24 , each portion 54, 56 of the second rotor 24 includes one or more lobes 58 with an opposite configuration to the corresponding helical lobes 30, 32 of the first rotor 22. In the illustrated non-limiting embodiment, the first portion 54 of the second rotor 24 has at least one right lobe 58a, and the second portion 56 of the second rotor 24 includes at least one left lobe 58b.

In one embodiment, the first portion 54 of the second rotor 24 is configured to rotate independently of the second portion 56 of the second rotor 24. However, embodiments in which the first and second portions 54, 56 are mutually coupled are also contemplated here. rotary. Each portion 54, 56 of second rotor 24 may include any number of lobes 58. In one embodiment, the total number of lobes 58 formed on each portion 54, 56 of second rotor 24 is generally greater than that on the corresponding portion of first rotor 24. For example, if the first rotor 22 includes four first helical lobes 30, the first portion 54 of the second rotor 24 configured to mesh with the first helical lobes 30 may include five helical lobes 58a. However, embodiments in which the total number of lobes 58 in a portion 54, 56 of the second rotor 24 is equal to a corresponding group of helical lobes (i.e., the first helical lobes 30 or the second helical lobes 32) of the first rotor 22 are also within the scope of the invention.

Returning to Figure 1, during operation of the fluid machine 20 of one embodiment, a gas or other fluid, such as, for example, a low GWP refrigerant, is drawn to a central location by a suction process generated by the fluid machine 20. The rotation of the first rotor 22 and the second rotor 24 compresses the coolant and forces the coolant towards the outer ends 38, 40 of the casing 36 due to the structure and function of the opposed helical rotors 22, 24. The compressed refrigerant is directed by an internal gas passage within the casing 36 and discharged through the upper end 40 of the casing 36. The discharged refrigerant passes through the electric motor 48 and exits through the discharge outlet 59.

Referring now to Figures 3-7, the fluid machine 20 includes one or more lubricant supply passages for providing a lubricant from a manifold 61 to the dynamic interfaces of the machine 20. In one embodiment, the manifold 61 containing a volume of lubricant, such as, for example, oil, is located adjacent to and in communication with the lower bearing housing 42. A first shaft passage 60 extends axially through at least a portion of the first shaft 34. In the illustrated non-limiting embodiment, the first shaft passage 60 extends from near the lower end 38 of the housing 36 to near the upper end 40 of the housing 36.

As best shown in Figures 4 and 5, in one embodiment, a cavity 68 formed in the upper bearing housing 64 is configured to surround a periphery of a portion of the first shaft 34. At least one radial hole 70 extends between the first shaft passage 60 to the outer surface of shaft 34 to supply lubricant to cavity 68. In the illustrated non-limiting embodiment, two radial holes 70 extend in opposite directions from each other from the first shaft passage 60 to the outer surface of the shaft. shaft 34. In addition, one or more bore surfaces formed in the upper bearing portion 44 and configured to contact the first shaft 34 may function as a bearing. For example, referring to Figure 5, a first surface 72 disposed adjacent a first side of cavity 68 may function as a main bearing and a second surface 74 disposed adjacent an opposite second side of cavity 68 may function as a main bearing. as an auxiliary bearing. Similarly, the hole formed in a lower bearing portion 62 to receive a portion of the first shaft 34 includes a surface 76 that can function as a bearing.

In one embodiment, a groove 80 extends the axial length of surface 72. This groove 80 is disposed in fluid communication with cavity 68 and is configured to distribute lubricant from cavity 68 along the axial length of first surface 72. On the other hand, or in addition, a groove 84 extends the axial length of surface 76. Groove 84 is configured to dispense lubricant from manifold 61 disposed adjacent lower bearing housing 42.

A second shaft pitch 86 extends axially through the lower bearing housing 42 and at least a portion of the second shaft 50. In the illustrated non-limiting embodiment, the second shaft pitch 86 extends approximately half the length axis of the second shaft 50. However, a shaft pitch 86 of any length is contemplated here. Referring now to Figure 6, an axially extending passage 88 is formed through an outer periphery of second shaft 50 and at least one radial bore 90 fluidly engages shaft passage 86 and axial passage 88. In one embodiment , the radial hole is disposed generally centrally with respect to the axial passage such that a portion of the lubricant is distributed in two directions with respect to the radial hole 90. However, embodiments in which the radial hole 90 is located are also contemplated here. disposed adjacent to one end of the passage 88 or elsewhere. Axial passage 88 is configured to distribute lubricant at the interface formed between second shaft 50 and bore 52 formed in second rotor 24. In one embodiment, axial passage 88 extends between upper and lower bearing housings 44, 42. .

During operation of the fluid machine 20, the relatively high pressure discharge at the outer ends 38, 40 of the casing 36, and the relatively low pressure suction at a central location of the first rotor 22 and second rotor 24, drive or draw lubricant from the manifold 61 through the lubricant supply passages associated with the first and second rotors 22, 24. More specifically, the lubricant will flow from the manifold 61 through the first shaft passage 60, to the axial groove 84 formed on the surface 76 of the lower bearing housing 42, and through the second shaft passage 86 simultaneously. The lubricant supply passages are intended to lubricate the surfaces 72, 74 and 76 of the upper and lower bearing housings 42, 44 which function as bearings for the first shaft 34, and the interface between the second shaft 50 and the second rotor. 24 to reduce friction between them.

A counterbore 78, 82, 92, 94 may be formed in the surfaces of the lower bearing housing 42 and the upper bearing housing 44 that face respectively toward the first and second rotors 22, 24. The counterbore 78 may be arranged in fluid communication with the groove 80. The counterbore 82 may be disposed in fluid communication with the groove 84. As a result, the lubricant will flow to each of the counterbores 78, 82 after lubricating the respective surfaces 72, 74 and 76. In addition, the counterbore hole 92, 94 may be disposed in fluid communication with the axial passage 88. As a result, lubricant will flow into the counterbore 92, 94 after lubricating the interface between the second shaft 50 and the second rotor 24. In one embodiment, a recess 96 it may extend from one or more of the counterbored holes 78, 82, 92, 94 at an angle toward the interface between the first rotor 22 and the second rotor 24. Although the fluid machine illustrated and described herein includes a recess formed in each one of the counterbores, embodiments where none or only some of the counterbores include a recess are also within the scope of the invention.

The configuration of each recess 96, such as, for example, angle, length, width, and depth, can be optimized to control the amount of lubricant flow to the compression pocket. In one embodiment, the recess 96 has a linear contour and is aligned with the interface between the lobes 30, 32 of the first rotor 22 and the corresponding lobes 58a, 58b of the second rotor 24. Accordingly, as shown in Fig. 6 , the angle of the recess 96 with respect to the axis extending through the origin of both the first and second shafts 34, 50 is between 0 degrees and 60 degrees.

By placing the recess 96 in alignment with the meshing engagement of the rotors 22, 24, the recess communicates with both the high and low pressure areas adjacent to the first rotor 22 and second rotor 24. As a result, it can flow lubricant from the recess 96 by the compression pocket formed between the first and second rotors 22, 24. In one embodiment, the length of the recess 96, measured radially from the origin of the hole to receive a corresponding shaft 34 or 50, is greater than the radius of the root of the rotor 22 or 24. In addition, the length of the recess 96 may be greater than the radius of the root, but less than the radius of the tip of the associated rotor 22 or 24. In one embodiment, a width of the recess 96, measured perpendicular to the length, is between 1 mm and 10 mm, and a depth of the recess 96 extending into the lower or upper bearing housing 42, 44 is between 1 and 10 mm. 5 times the axial length of the clearance between the rotor 22 or 24 and the adjacent surface of the lower or upper bearing housing 42, 44. It should be understood that in embodiments that include a plurality of recesses, the configuration of the recesses may be as same or, alternatively, it can be different.

The fluid machine 20 illustrated and described herein provides a simple, low cost configuration for a lubricant supply system. Because the pressure of the machine 20 is used to draw fluid to the respective interfaces, expensive devices, such as, for example, a pump or control valve, are not required. Furthermore, because the lubricant is driven by the differential pressure created during operation of the machine 20, a stable supply of lubricant is provided over a wide range of shaft speeds.

Although the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to the described embodiments. Rather, the invention may be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but which are within the scope of the appended claims. Accordingly, the invention should not be limited by the above description, but only by the scope of the appended claims.

Claims (15)

1. Fluid machine (20) comprising: a casing (36); a first rotor (22) fixed to a first shaft (34), the first rotor and the first shaft being rotatable about a first axis, wherein the first shaft is rotatably supported on the casing; a second rotor (24) is supported by a second shaft (50), the second rotor being able to rotate about a second axis, in which the second rotor is configured to rotate about the second shaft and in which the second shaft is supported on the casing and is fixed relative to it; a manifold (61) containing a volume of lubricant therein; a first lubricant passage for supplying manifold lubricant to a dynamic interface associated with the first rotor; Y a second lubricant passage for supplying manifold lubricant to a dynamic interface associated with the second rotor; wherein a differential pressure created within the fluid machine supplies the lubricant from the manifold to the first lubricant passage and the second lubricant passage simultaneously. 2. Fluid machine according to claim 1, wherein during operation of the fluid machine (20), differential pressure is formed between a high pressure adjacent to at least one end (38, 40) of the housing (36 ) and a low pressure at a central location of the first rotor (22) and the second rotor (24). Fluid machine according to claim 1 or 2, in which the first rotor (22) and first shaft (34) are rotatably mounted in the housing (36) without roller bearings. 4. Fluid machine according to any preceding claim, wherein at least one surface (72, 74, 76) of the casing (36) and the first shaft (34) define the dynamic interface associated with the first rotor (22). ). 5. Fluid machine according to claim 4, wherein at least one surface (72, 74, 76) of the casing (36) disposed in direct contact with the first shaft (34) functions as a bearing. The fluid machine of claim 5, wherein at least one housing surface (36) disposed in direct contact with the first shaft (34) includes a first surface (72) disposed in direct contact with a portion of the first shaft (34) adjacent to a first end (38), and a second surface (74) disposed in direct contact with a portion of the first shaft (34) adjacent to a second end (40). 7. Fluid machine according to claim 6, wherein the first lubricant passage includes a first part for supplying lubricant to the first surface (72) and a second part, different from the first part, for supplying lubricant to the second surface (74). 8. Fluid machine according to any of the preceding claims, wherein the first lubricant step further comprises: a cavity (68) formed in a portion of the casing (36) adjacent to the first shaft (34); a passageway (60) extending axially through at least a portion of the first shaft (34); at least one radial hole (70) that engages the cavity (68) and the passage (60); Y a slot (80) extending from the cavity (68) to an interior of a compression pocket formed between the first rotor (22) and the second rotor (24) and the casing (36). 9. Fluid machine according to claim 8, wherein the first lubricant step further comprises: a counterbore (78, 82) formed at the interface between the casing (36) and the compression pocket. 10. Fluid machine according to any of the preceding claims, wherein the first lubricant step comprises: a slot extending from the manifold to an interior of a compression pocket formed between the first rotor (22) and the second rotor (24) and the casing (36). 11. Fluid machine according to any of the preceding claims, wherein the second rotor (24) comprises: a working part rotatable with respect to the second shaft (50), wherein the second shaft (50) and the working part define the dynamic interface associated with the second rotor (24). 12. Fluid machine according to any of the preceding claims, wherein the second lubricant step further comprises: a first passageway (86) extending axially through at least a portion of the second shaft (50); a second passage (88) formed at an outer periphery of the second shaft (50); Y at least one radial hole (90) engaging the first passage (86) and the second passage (88); optionally wherein the second passage (88) extends axially such that a first end of the second passage (88) fluidly engages a first housing portion (36) and an opposite second end of the second passage (88) ) fluidly engages a second housing part (36). 13. Fluid machine according to any of the preceding claims, wherein a counterbore (78, 82, 92, 94) is formed in the housing (36) where at least one of the first lubricant passage and the second passage of lubricant enters a compression pocket formed between the first rotor (22) and the second rotor (34); optionally wherein the fluid machine further comprises a recess (96) formed in the housing (36) in fluid communication with the counterbore (78, 82, 92, 94), the recess (96) being disposed at an angle toward an interface between the first rotor (22) and the second rotor (24); optionally further, wherein at least one of an angle, a length, a width, and a depth of the recess (96) is optimized to control a flow of lubricant into the compression pocket. 14. A method of lubricating one or more dynamic interfaces of a fluid machine (20), the fluid machine (20) comprising a housing (36), the method comprising: supplying lubricant from a manifold (61) to a dynamic interface associated with a first rotor (22) attached to a first shaft (34) of the fluid machine through a first lubricant passage, wherein the first rotor (22) ) and the first shaft (34) are rotatable about a first axis, and wherein the first shaft (22) is rotatably supported on the housing (36); Y supplying lubricant from a manifold (61) to a dynamic interface associated with a second rotor (24) bearing on a second shaft (50) of the fluid machine (20) through a second lubricant passage, the second being lubricant passage other than the first lubricant passage, wherein the second rotor (24) is rotatable about a second axis, wherein the second rotor (24) is configured to rotate about the second shaft (50) and in in which the second shaft rests on the casing (36) and is fixed with respect to it; wherein the supply of lubricant to the dynamic interface associated with the first rotor (22) and the dynamic interface associated with the second rotor (24) occurs automatically and simultaneously in response to a differential pressure created within the machine fluids (20) during the operation of the fluid machine. 15. Method according to claim 14, wherein the supply of lubricant from the manifold (61) to the dynamic interface associated with the first rotor (22) and the supply of lubricant from the manifold (61) to the dynamic interface associated with the second rotor (24) is produced without a pump or a control valve; me wherein the supply of lubricant from the manifold (61) to the dynamic interface associated with the first rotor (22) further comprises: supplying lubricant through a first passage to a first bearing surface, the first passage extending through an opening formed in the first shaft (34) of the first rotor (22); Y supplying lubricant through a second passage to a second bearing surface; me wherein the method further comprises supplying lubricant from the dynamic interface associated with the first rotor (22) and the dynamic interface associated with the second rotor (24) to a compression pocket formed between the first rotor (22) and the second rotor (24).