MULTI-STAGE HOOK AND CLAW COMPRESSOR ASSEMBLY

Abstract

A multi-stage compressor system for compressing a working fluid includes a compressor housing and a drive unit configured to drive a first shaft and a second shaft. The first shaft defines a first axis of rotation and the second shaft defines a second axis of rotation, where the first axis is parallel to the second axis of rotation. The compressor system further includes a first airend and a second airend operable to receive and compress the working fluid. The first airend includes a first rotor configured to be driven by the first shaft and a second rotor configured to be driven by the second shaft. The second airend further compresses the working fluid received from the first airend, and includes a third rotor configured to be driven by the first shaft and a fourth rotor configured to be driven by the second shaft.

Claims

1. A multistage air compressor configured to compress a working fluid, the two-stage air compressor comprising: a single compressor housing having a first airend and a second airend; a drive unit configured to drive a first shaft and a second shaft, the first shaft defining a first axis of rotation and the second shaft defining a second axis of rotation, the first axis of rotation parallel to the second axis of rotation, the first shaft having a first end configured to be driven by the drive unit; the first airend operable to receive and compress the working fluid, the first airend including a first rotor configured to be driven by the first shaft and a second rotor configured to be driven by the second shaft, the first rotor and the second rotor defining a first rotor pair; the second airend operable to receive the working fluid from the first airend and further compress the working fluid, the second airend including a third rotor configured to be driven by the first shaft and a fourth rotor configured to be driven by the second shaft, the third rotor and the fourth rotor defining a second rotor pair, wherein the first rotor and the third rotor are disposed at a center distance from the second rotor and the fourth rotor, respectively.

2. The multistage air compressor of claim 1, wherein at least one of the first rotor pair or the second rotor pair is a conjugate pair.

3. The multistage air compressor of claim 1, wherein at least one of a bore diameter of the first rotor or a bore diameter of the third rotor is equal to a bore diameter of the second rotor or a bore diameter of the fourth rotor, respectively.

4. The multistage air compressor of claim 1, wherein at least one of a bore diameter of the first rotor or a bore diameter of the third rotor is different to a bore diameter of the second rotor or a bore diameter of the fourth rotor, respectively.

5. The multistage air compressor of claim 1, wherein the bore diameter of the first rotor pair in the first airend is different than a bore diameter of the second rotor pair in the second airend.

6. The multistage air compressor of claim 1, wherein a rotor profile of the first rotor pair is different than a rotor profile of the second rotor pair.

7. The multistage air compressor of claim 6, wherein one of the rotor profile of the first rotor pair is a hook and claw rotor profile and the rotor profile of the second rotor pair has a lobe rotor profile.

8. The multistage air compressor of claim 6, wherein the first rotor pair has a first rotor width, and second rotor pair has a second rotor width, and wherein the first rotor width is equal to the second rotor width.

9. The multistage air compressor of claim 1, wherein the first rotor pair has a first rotor width, and second rotor pair has a second rotor width, and wherein the first rotor width is different from the second rotor width.

10. The multistage air compressor of claim 1, wherein the compressor housing includes a partitioning wall configured to separate the first airend from the second airend.

11. The multistage air compressor of claim 1, further comprising a timing gear assembly mounted on the first shaft and the second shaft, the timing gear assembly configured to synchronously drive the second shaft with respect to the first shaft.

12. The multistage air compressor of claim 1, wherein the first airend has a first mass flow rate and a first volumetric flow rate, and the second airend has a second mass flow rate and a second volumetric flow rate, where the first mass flow rate and the second mass flow rate are equal to each other, and where the first volumetric flow rate is greater than the second volumetric flow rate.

13. The multistage air compressor of claim 1, wherein the compressor housing defines a cooling channel disposed within inner side wall of the compressor housing configured to circulate a coolant between the first airend and the second airend and inhibit heat conduction between the first airend and the second airend.

14. The multistage air compressor of claim 1, further comprising an intercooler disposed between the first airend and the second airend, the intercooler configured to cool the working fluid prior to entering the second airend.

15. The multistage air compressor of claim 1, where a first inlet port of the first airend and a second inlet port of the second airend open synchronously to receive the working fluid.

16. The multistage air compressor of claim 1, where a first inlet port of the first airend and a second inlet port of the second airend open asynchronously to receive the working fluid.

17. A multistage fluid compressor system comprising: a hook and claw (HC) compressor assembly for configured to compress a working fluid, the HC compressor assembly including: a single compressor housing containing multiple stages that compress the working fluid, a drive unit configured to drive a first shaft and a second shaft, the first shaft defining a first axis of rotation and the second shaft defining a second axis of rotation, the first axis of rotation parallel to the second axis of rotation, the first shaft having a first end configured to be directly driven by the drive unit, a first airend housed in the compressor housing and operable to receive and compress the working fluid, the first airend including a first rotor configured to be driven by the first shaft and a second rotor configured to be driven by the second shaft, and a second airend housed in the compressor housing and operable to receive the working fluid from the first airend and further compress the working fluid, the second airend including a third rotor configured to be driven by the first shaft and a fourth rotor configured to be driven by the second shaft; and a cooling system configured to circulate a coolant between the first airend and the second airend and inhibit heat conduction between the first airend and the second airend.

18. The multistage fluid compressor system of claim 17, wherein a rotor profile of the first rotor pair is different than a rotor profile of the second rotor pair.

19. The multistage fluid compressor system of claim 18 wherein the first rotor pair has a first rotor width, and second rotor pair has a second rotor width, and wherein the first rotor width is different from the second rotor width.

20. A multistage air compressor configured to compress a working fluid, the two-stage air compressor comprising: a single compressor housing having a first airend and a second airend; a drive unit configured to drive a first shaft and a second shaft, the first shaft defining a first axis of rotation and the second shaft defining a second axis of rotation, the first axis of rotation parallel to the second axis of rotation, the first shaft having a first end configured to be driven by the drive unit; the first airend operable to receive and compress the working fluid, the first airend including a first rotor configured to be driven by the first shaft and a second rotor configured to be driven by the second shaft, the first rotor and the second rotor defining a first rotor pair; the second airend operable to receive the working fluid from the first airend and further compress the working fluid, the second airend including a third rotor configured to be driven by the first shaft and a fourth rotor configured to be driven by the second shaft, the third rotor and the fourth rotor defining a second rotor pair, wherein the first rotor and the third rotor are disposed at a center distance from the second rotor and the fourth rotor, respectively, and wherein the first rotor pair has a first rotor width, and second rotor pair has a second rotor width, and wherein the first rotor width is different from the second rotor width.

Description

DRAWINGS

[0003] The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items.

[0004] FIG. 1 is a schematic view of a compressor system including a multi-stage compressor assembly in accordance with example embodiments of the present disclosure.

[0005] FIG. 2 is an isometric front view of a multi-stage compressor assembly in accordance with example embodiments of the present disclosure.

[0006] FIG. 3 is a top cross-sectional view of the multi-stage compressor assembly shown in FIG. 2, along line 3-3, in accordance with example embodiments of the present disclosure.

[0007] FIG. 4 is a partial cross-sectional view of a silencer chamber of the compressor assembly shown in FIG. 2, along line 4-4, in accordance with example embodiments of the present disclosure.

[0008] FIG. 5 is a partial cross-sectional view of a silencer chamber of the compressor assembly shown in FIG. 2, along line 4-4, in accordance with other example embodiments of the present disclosure.

[0009] FIG. 6 is a cross-sectional side view of the multi-stage compressor assembly shown in FIG. 2, along line 6-6, in accordance with example embodiments of the present disclosure.

[0010] FIG. 7 is a schematic view of a hook and claw rotor pair profile configured for use in the compressor assembly shown in FIG. 2, in accordance with example embodiments of the present disclosure.

[0011] FIG. 8 is a schematic view of a hook and claw rotor pair profile configured for use in the compressor assembly shown in FIG. 2, in accordance with other example embodiments of the present disclosure.

[0012] FIG. 9 is a schematic view of a lobe rotor pair profile configured for use in the compressor assembly shown in FIG. 2, in accordance with other example embodiments of the present disclosure.

DETAILED DESCRIPTION

[0013] Although the subject matter has been described in language specific to structural features and/or process operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Overview

[0014] Fluid compressor systems increase the pressure of a working fluid such as air or gas, and are widely used in a variety of industries such as in construction, manufacturing, agriculture, energy production, etc. There are generally two categories of compressors: Positive Displacement and Dynamic Compressors. Both categories of compressors have subcategories that at a component level are described in the industry as airends.

[0015] Positive displacement compressor systems such as, but not limited to, hook and claw compressors and rotary screw compressors, confine a successive volume of the working fluid within a closed space that is mechanically reduced, compressing the working fluid and increasing the working fluid's pressure and temperature. Hook and claw compressors may also be configured to operate as vacuum pumps. Vacuum pumps create a vacuum in a confined volume by removing air from the volume thereby creating a low-pressure region.

[0016] Hook and claw compressors are oil-free rotary (OFR) compressors that contain two rotors turning in opposite directions inside a compressor housing. These rotors are not in contact with each other or the housing. Consequently, hook and claw compressors, like other OFR compressors, do not inject a lubricant into the compression cavity. Hook and claw compressors have a linear relationship between the volume curve and the angle of the rotors, in other words, as the rotors turn (i.e., the rotor's angle increases), the volume of air decreases linearly. Traditionally, two-stage hook and claw compressors are composed of separate first and second stage airends, each having a separate housing, driven by a common bull gear system or independently driven by a corresponding drive. Either drive system increases the entire frame size of the compressor assembly. Moreover, a compressor assembly having separate airends and a bull gear increases the cost, complexity, and number of parts needed to service/maintain the compressor assembly. A compressor assembly having a reduced footprint and a smaller overall package size, while maintaining the same performance of traditional multi-stage hook and claw compressors is desired.

[0017] The present disclosure is directed to a fluid compressor system, and more specifically to a multi-stage compressor assembly configured to compress a working fluid using at least two compression stages, or two separate airends, housed within a single compressor housing. In embodiments, the multi-stage compressor assembly comprises a two-stage compressor assembly that includes a first shaft, a second shaft, and a drive unit that drives the first shaft and the second shaft. The first shaft has a first axis of rotation and the second shaft has a second axis of rotation, with both axes of rotation being parallel to one another. In embodiments, the first and second shafts turn in opposite directions (i.e., one shaft turns in a clockwise direction while the other shaft turns in a counterclockwise direction).

[0018] The compressor system includes a first airend and a second airend formed within a common compressor housing, both of which are capable of receiving and compressing the working fluid such that the second airend further compresses the (compressed) working fluid received from the first airend The compressor housing defines a first airend cavity having a first bore diameter for the first airend and a second airend cavity having a second bore diameter for the second airend, where the first bore diameter is equal to the second bore diameter. The first airend includes an intermeshed first rotor driven by the first shaft and second rotor driven by the second shaft. The second airend includes a third rotor driven by the first shaft and a fourth rotor driven by the second shaft. The center distance between the first rotor and the second rotor in the first airend is generally identical to the center distance between the third rotor and the fourth rotor. This configuration allows the compressor assembly to maintain performance while reducing the overall footprint and package size compared to traditional multi-stage hook and claw compressors.

Detailed Description of Example Embodiments

[0019] Referring generally to FIG. 1, a fluid compressor system 10 is shown. The fluid compressor system 10 includes a multi-stage compressor assembly 100 having at least first airend 121 and a second airend 125, and a coolant circulation system 146. The coolant circulation system 146 includes at least a cooler 148. In embodiments, the fluid compressor system 10 includes at least an intercooler 142 and an aftercooler 144. The fluid compressor system may include an inlet air filter 135 to filter an incoming compressible working fluid (e.g., air, gas, etc.) prior to the working fluid entering the first airend 121. Although the disclosure discusses a multi-stage compressor assembly, it should be understood that the fluid compressor system 10 may include multiple compression stages where each stage discharge enters a subsequent stage inlet until the desired discharge pressure is achieved. Other elements including a plurality of interstage coolers, valves, separators, and the like may be included in the fluid compressor system 10. It should be understood that the fluid compressor system 10 is not limited to the arrangement shown in the example embodiment of FIG. 1.

[0020] The multi-stage compressor assembly 100 includes a compressor housing 102. In example embodiments, shown in FIGS. 2 through 6, the compressor housing 102 includes endcaps 107 disposed at a first end 99 and a second end 101 of the compressor housing 102. The multi-stage compressor assembly 100 includes a first airend 121 and a second airend 125. The first airend 121 and the second airend 125 are configured to compress the working fluid to a desired pressure. The first airend 121 includes a first airend cavity 103 defined on the compressor housing 102. The second airend 125 includes a second airend cavity 105 defined on the compressor housing 102. The first airend cavity 103 and the second airend cavity 105, respectively, house a first airend 121 and a second airend 125. The compressor housing 102 includes a partitioning wall 132 that separates the first airend 121 from the second airend 125. In embodiments, the first airend 121 and the second airend 125 are not in fluid communication through the partitioning wall 132. The fluid compressor system 100 may include a drive unit 140 (e.g., a motor) driving the first airend 121 and the second airend 125.

[0021] The drive unit 140 drives the first airend 121 and the second airend 125 via the first shaft 114. The drive unit 140 may be an electric motor, a hydraulic motor, a pneumatic motor, a steam motor, or an internal combustion engine, or other source of motion that would rotate the first shaft 114. In embodiments, the drive unit 140 is directly coupled to the first shaft 114. In other embodiments, the drive unit 140 may be indirectly coupled to the first shaft 114 via a gear train, a belt drive mechanism, among others. A second shaft 116 is driven by the first shaft 114. The second shaft 116 is driven by the first shaft 114 through a gear assembly 118.

[0022] The gear assembly includes at least a pair of intermeshing gears 119. Each one of the pair of gears 119 is respectively coupled to the first shaft 114 and the second shaft 116. The gear assembly 118 synchronously drives the second shaft 116 with respect to the first shaft 114. The gear assembly 118 may be disposed at an end of the first shaft 114 and the second shaft 116, for example, proximate to the first end 99 of the compressor housing 102 (e.g., adjacent to the first airend 121). In other embodiments (not shown), the gear assembly 118 is disposed proximate to the second end 101 of the compressor housing (e.g., adjacent to the second airend 125).

[0023] The first shaft 114 defines a first axis of rotation 114X and the second shaft 116 defines a second axis of rotation 116X. In embodiments, the first axis of rotation 114X is parallel to the second axis of rotation 116X, so that the first shaft 114 and the second shaft 116 are parallel to one another. The first shaft 114 drives one rotor from the first airend 121 and one rotor from the second airend 125. The second shaft 116 drives another rotor from the first airend 121 and another rotor from the second airend 125 in a direction opposite to the direction driven by the first shaft 114.

[0024] The compressor assembly 100 may also include a bearing system including a plurality of bearings 134 configured to support the rotation of the first shaft 114 and the second shaft 116. In embodiments, each one of the first shaft 114 and the second shaft 116 may be supported by three (3) bearings 134. The bearings may be disposed at a first end of the first shaft 114, a second end of the first shaft 114, a first end of the second shaft 116, a second end of the second shaft 116, and proximate to the internal side wall 113 between the first airend 121 and the timing gears 118.

[0025] In other embodiments, the bearing system may be composed of four (4) bearings 134 and have a bearing 134 at each end of the rotors 114 and 116. In other embodiments, the fluid compressor system includes a six (6) bearing system where four (4) bearings 134 are coupled to each opposing end of the rotors 114 and 116 and two (2) bearings 134 are located between the first airend 121 and the second airend 125. In either bearing configuration the parting wall 132 is used to separate the two stages of compression.

[0026] In other embodiments, such as the embodiment shown in FIGS. 3, the bearings may be disposed at a first end of the first shaft 114, a second end of the first shaft 114, a first end of the second shaft 116, a second end of the second shaft 116, and proximate to the back wall 131, between the first airend 121 and the gear assembly 118. The bearing system may also include a plurality of seals 133 coupled to the first shaft 114 and second shaft 116. The plurality of seals may maintain a seal that blocks fluid communication between the first airend 121 and the second airend 125 along the first shaft 114 and second shaft 116.

[0027] The first airend 121 has a first volumetric flow rate, or the volume of working and the second airend 125 has a second volumetric flow rate, determined by the compression ratio the compressor assembly 100. In embodiments, the first volumetric flow rate is greater than the second volumetric flow rate. As the pressure and density of the working fluid increase, the volumetric flow rate decreases. In other embodiments, the first volumetric flow rate may be approximately equal to the second volumetric flow rate.

[0028] The first airend 121 includes a first rotor pair 123 including a first rotor 120 and a second rotor 122. The first rotor 120 is positioned axially parallel to the second rotor 122. The first rotor 120 is driven by the first shaft 114 along the first axis of rotation 114X and the second rotor 122 is driven by the second shaft 116 along the second axis of rotation 116X. The first rotor 120 and the second rotor 122 are mutually complementary and rotate in opposite directions. The working fluid is trapped between the outer surface of the first rotor 120, the second rotor 122, and the first airend cavity 103 inner walls as the rotors 120 and 122 rotate, compressing the working fluid entering the first airend 121.

[0029] The second airend 125 includes a second rotor pair 127 including a third rotor 124 and a fourth rotor 126. The third rotor 124 is positioned axially parallel to the fourth rotor 126. The third rotor 124 is driven by the first shaft 114 along the first axis of rotation 114X and the fourth rotor 126 is driven by the second shaft 116 along the second axis of rotation 116X. The third rotor 124 and the fourth rotor 126 are mutually complementary and rotate in opposite directions. The working fluid is trapped between the outer surface of the third rotor 124, the fourth rotor 126, and the second airend cavity 105 inner walls as the rotors 124 and 126 rotate, compressing the working fluid entering the second airend 125.

[0030] As shown, the first rotor 120 and the second rotor 122 have a first rotor width W.sub.1, and the third rotor 124 and the fourth rotor 126 have a second rotor width W.sub.2. In embodiments, the first rotor width W.sub.1 is different from the second rotor width W.sub.2. For example, as shown in FIG. 3, the first rotor width W.sub.1 is greater than the second rotor width W.sub.2.

[0031] In example embodiments, one or both of the first rotor pair 123 and the second rotor pair 127 are conjugate rotor pairs. Conjugate rotor pairs are pairs of intermeshing rotors in which the two rotor profiles maintain continuous tangential contact during operation, there is no slippage between the two rotor surfaces, and the rotors are rotating at the same angular speed, preventing contact between the surfaces of the rotor pairs.

[0032] As previously discussed, two-stage compressors involve a two-stage compression process. Multi-stage compressors may include N-stage compression processes. In example embodiments, the inlet pressure at the first stage is at atmospheric pressure. The first airend 121 gauge pressure may be between approximately two (2) barG and three (3) barG. The second airend 125 pressure may be between approximately four (4) barG and approximately twelve (12) barG. In embodiments, the second airend 125 pressure is between six (6) barG and ten (10) barG. It should be understood that these values are example pressure measurements and are not intended to limit the scope of the disclosure.

[0033] In example embodiments, the pressure ratio between the first airend 121 and the second airend 125 is between 1:2 and 1:4. In embodiments where the bore diameter of the first airend is equal to the bore diameter of the second airend, the displacement volume is a function of the rotor width, and there is a linear relationship between the volume curve versus the angle of the rotors. In these embodiments, the pressure ratio would be directly proportional to the ratio between the second rotor width W.sub.2 and the first rotor width W.sub.1. For example, to obtain a 1:3 pressure ratio, the ratio W.sub.2:W.sub.1 would also be 1:3.

[0034] In embodiments, the first rotor pair 123 and the second rotor pair 127 have identical rotor profiles. In other embodiments, the first rotor pair 123 and the second rotor pair 127 may have different rotor profiles to achieve a lower airend discharge pressure or a higher airend discharge pressure based on the volumetric flow of the working fluid introduced into the airend cavity by the rotors. The rotor profile is the general shape of a cross-section of the rotors. Examples of rotor profiles are shown in FIGS. 7 through 9. FIGS. 7 and 8 show example hook and claw rotor profiles. As shown in FIG. 9, the rotor profiles may also include lobed rotors. For example, the first rotor pair 123 may have a profile such as the profile shown in FIG. 7, where at least one of the rotors of the first rotor pair 123 has a flat or linear portion connecting compound curves including convex portions and concave portions of the cross-section of the rotor. The second rotor pair 127 may have a profile such as the profile shown in FIG. 8, where the cross-sectional profile of the rotors includes compound curves having concave and convex portions, and no portion of the profile are flat or linear. It should be understood that these rotor profiles are not limiting and other hook and claw or lobed profiles could be used in either one or both of the first rotor pair 123 and the second rotor pair 127.

[0035] In embodiments where the first rotor pair 123 and the second rotor pair 127 have different rotor profiles, the second rotor pair 127 compressing the working fluid in the second stage may have a profile that can receive and hold a higher volumetric flow of working fluid from the second airend intake 110 to compress further. In embodiments, the second rotor pair 127 may have more intermeshing claws or lobes than the first rotor pair 123, and vice versa, the first rotor pair 123 may have more intermeshing claws or lobes than the second rotor pair 127. In embodiments as shown in FIG. 2, the first airend intake 106 and/or the second airend intake 110 may be positioned on a top portion of the first airend cavity 103 and/or the second airend cavity 105, respectively. In other embodiments (not shown), the first airend intake 106 and/or the second airend intake 110 may be positioned on one or both sides of the first rotor pair 123 and/or the second rotor pair 127, respectively. In embodiments where the first rotor pair 123 and/or the second rotor pair 127 have a lobe blower profile as shown in FIG. 9, the discharge ports 108 and 112 may be disposed at a bottom side of the respective airend cavity.

[0036] The first rotor 120 and the third rotor 124 are rotated by the first shaft 114 about the first axis of rotation 114X, and the second rotor 122 and the fourth rotor 126 are rotated by the second shaft 116 about the second axis of rotation 116X. The axis of the first rotor 120 is at a center distance from the axis of the second rotor 122. The axis of the third rotor 124 and the axis of the fourth rotor 126 have the same center distance as the axis of the first rotor 120 and the axis of the second rotor 122. In embodiments, the gear assembly 118 maintains a constant speed and a constant clearance gap between the first rotor 120 and second rotor 122 and between the third rotor 124 and the fourth rotor 126. In embodiments, the first shaft 114 and/or the second shaft 116 may be split into two or more coaxial shafts, coupled from one end of a first coaxial shaft to one end of a second coaxial shaft. In this embodiment, each of the coaxial shafts may support one of the rotors of the first rotor pair 123 and/or the second rotor pair 127.

[0037] The first airend 121 receives a compressible working fluid (e.g., air, gas, etc.) through a first airend intake 106 and compresses the working fluid. In the embodiment shown, the first airend intake 106 is disposed on a top side of the compressor housing 102. However, in other embodiments, the first airend intake 106 may be positioned on an internal sidewall 113 in an axial direction form the first and second rotors 120 and 122. In embodiments, the working fluid enters the first airend 121 at a pressure set by the customer. For example, the working fluid entering the first stage compression process may be air at atmospheric pressure. After being compressed in the first airend 121, the working fluid exits the first airend cavity 103 through a first stage discharge port 108 and through a discharge cavity 109. The first discharge port 108 may be positioned on one of the internal side walls 113 of the compressor housing 102 defining the first airend cavity 103. In embodiments (not shown), the first airend 121 may have more than one discharge port 108 disposed at opposite sides of the rotor pair 123

[0038] As shown in FIG. 1, in embodiments, the fluid compressor system 10 includes the intercooler 142 configured to cool the working fluid delivered by the first airend 121 through the first discharge port 108. The second airend 125 receives the working fluid delivered by the intercooler 142 through a second airend intake 110. The second airend 125 further compresses the working fluid and discharges the working fluid through a second airend 125 discharge port 112. In some embodiments, the working fluid may then be delivered to an aftercooler 144 to further cool the working fluid prior to delivery.

[0039] As shown in FIGS. 3 and 6, the compressor system 100 may include a housing cooling channel 136 defined in the compressor housing 102. The housing cooling channel 136 is configured to circulate a coolant within the compressor housing to cool the compressor housing 102. The housing cooling channel 136 inhibits heat conduction between the first airend 121 and the second airend 125. The housing cooling channel 136 may be disposed within internal sidewalls 113 of the compressor housing 102 and surrounding the first airend 121 discharge cavity 109. The housing cooling channel 136 has a coolant inlet 137 and a coolant outlet 138. In embodiments, oil may be used as a coolant. However, in other embodiments a variety of different liquids or mixtures of fluid constituents can be used in accordance with the present disclosure. The coolant may be circulated by a coolant circulation system 146 including a cooler 148. The cooler 148 may be a heat exchanger, an evaporative cooler, or another cooling assembly configured to remove heat from the circulating coolant. The cooler is configured to remove heat from the coolant discharged by the coolant outlet 138 prior to recirculating the coolant to the compression system 100 through the coolant inlet 137. For example, in some embodiments it is contemplated that oil, water, and/or glycol solutions and combinations thereof, etc. may be used as a coolant.

[0040] The cooler 148 is configured to inhibit heat conduction within the first airend 121 and the second airend 125 portions of the compressor housing 102. In embodiments, the first airend 121 has a discharge temperature greater than one-hundred degrees Celsius (100 C.) and the second airend 125 has an inlet temperature between twenty degrees Celsius (20 C.) and fifty degrees Celsius (50 C.). Cooling the housing 102 keeps the working fluid entering the second airend 125 from reabsorbing heat removed by the intercooler 142. It should be understood that these temperatures are presented as examples and are not limiting factors of the fluid compressor system 100.

[0041] As shown in FIGS. 3 through 6, the second airend 125 discharge port 112 delivers the compressed working fluid to a silencer cavity 150. The silencer cavity 150 includes a silencer 152 configured to reduce the pressure pulsations of the two-stage compressor assembly 100 prior to discharging the working fluid through a discharge port 154. In this manner, the compressor assembly 100 may operate more quietly. It should be understood that the compressor assembly 100 may not include a silencer cavity 150 and discharge the compressed working fluid from the second airend 125 to the aftercooler 142 directly. In embodiments (not shown), the second airend 125 may have more than one discharge port 112 disposed at opposite sides of the rotor pair 127.

[0042] In the example shown in FIGS. 3 and 6, the silencer 152 comprises a perforated plate. In embodiments, the silencer 152 may be a reactive silencer, including reflective silencers and resonator silencers, an absorptive silencer, or a combination thereof. Reflective silencers provide single or multiple points of reflection through area changes in the cross-section of a pipe, as shown in FIGS. 4 and 5. Resonator silencers dissipate the acoustic energy at specific frequencies. Resonator silencers are used to attenuate a narrow band of frequencies, as such they must be tuned to effectively attenuate the sound energy. Dampening materials may be added to the neck of the resonator to increase the filter bandwidth. In absorptive silencers, acoustical absorption is achieved by sound energy transmitted by oscillating air molecules impacting porous material with the frequency of the exciting waves. In further embodiments (not shown), the silencer cavity 150 may be filled with absorptive material.

[0043] In embodiments (not shown), the fluid compressor system 100 may also include an inlet silencer disposed at the first stage intake 106 and/or a first discharge silencer disposed between the first airend 121 and the second airend 125. In embodiments, compressor housing 102 may be mounted on vibration mounts configured to reduce the vibrations of the two-stage compressor 100.

[0044] In embodiments, the fluid compressor system 10 may include a fluid filter 138 disposed upstream from the first airend 121. The fluid filter 138 filters particulate matter from the working fluid to prevents the particulate matter from entering the fluid compressor system 100. The fluid compressor system 10 may also include a first interstage moisture separator (e.g., intercooler 142) to remove moisture from the working fluid prior to the working fluid entering the second airend 125 and a second moisture separator (e.g., aftercooler 144) to separate moisture from the working fluid after being compressed by the second airend 125 and prior to the working fluid being delivered. It should be understood that other compressed air drying methods may be used between and/or in conjunction with either or both of the compression stages of the first airend 121 and the second airend 125.

[0045] In the embodiment shown in FIGS. 3 and 6, the compressor increases the pressure and temperature of the working fluid. In other embodiments, the compressor assembly 100 may be used as a vacuum pump, a subcategory of positive displacement compressors wherein the inlet pressure is lower than the discharge pressure. The compressor assembly 100 may reduce the pressure between the first and second stages and discharge the air at atmospheric conditions.

[0046] In the preceding description, it is understood that terms such as first, second, top, bottom, up, down, above, below, and the like, are words of convenience and are not to be construed as limiting terms.

[0047] While the subject matter has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the subject matters are desired to be protected. In reading the claims, it is intended that when words such as a, an, at least one, are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Unless specified or limited otherwise, the terms mounted, connected, supported, and coupled and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, connected and coupled are not restricted to physical or mechanical connections or couplings.