Roots compressor system

Abstract

A compressor assembly may include a main housing and a sound attenuation housing at least partially surrounding an outer periphery of the main housing. The sound attenuating housing may include a layer of sound attenuating material. The compressor may also include a seal assembly including a pair of seals on each rotor shaft of the compressor, with a vent valve disposed in fluid communication with a space between the pair of seals to prevent lubricating oil from diverting into the compressor airflow path.

Description

Technical Field

[0001] The present disclosure relates to compressors, and more particularly to compressors for air compressor applications. Background Art

[0002] Roots-type compressors, such as superchargers, are known. Such devices are known to be noisy and to leak lubricating oil into the main airflow path. Improvements are desired. Summary of the invention

[0003] A compressor assembly may include a compressor including a main housing having an inlet and an outlet, and may include a pair of rotors disposed within an internal cavity, each rotor of the pair of rotors having a plurality of lobes. The compressor assembly may also include a sound attenuation assembly at least partially surrounding an outer periphery of the main housing, the sound attenuation assembly including a sound attenuation layer.

[0004] In some examples, the main housing and the sound attenuating layer are separated by an intermediate gap.

[0005] In some examples, the sound attenuating layer is a foam material.

[0006] In some examples, the sound attenuating layer includes multiple separate components.

[0007] In some examples, the sound attenuating assembly includes an outer layer surrounding the sound attenuating layer.

[0008] In some examples, the outer layer is made of sheet metal.

[0009] In some examples, the outer layer is formed from a plurality of separate components.

[0010] A sound attenuation assembly for a compressor may include: an outer layer; and an inner layer, arranged within the outer layer, the inner layer being made of a sound attenuating material, the inner layer defining a peripheral wall extending between a first end wall and a second end wall, the first end wall including a first opening for surrounding a first end of the compressor so that a drive mechanism can be connected to the compressor, the second end wall including a second opening for surrounding a second end of the compressor having an air intake opening, the peripheral wall having an opening through which an outlet of the compressor can extend.

[0011] In some examples, the sound attenuating layer is a foam material.

[0012] In some examples, the sound attenuating layer includes multiple separate components.

[0013] In some examples, the sound attenuating assembly includes an outer layer surrounding the sound attenuating layer.

[0014] In some examples, the outer layer is made of sheet metal.

[0015] In some examples, the outer layer is formed from a plurality of separate components.

[0016] A compressor may include: a casing assembly having a first opening and a second opening connected to an internal cavity fluid; a pair of rotors arranged in the internal cavity, each of the pair of rotors having a plurality of blades; a pair of shafts supporting the pair of rotors; a pair of sealing assemblies providing sealing between the pair of shafts and the casing assembly, each of the pair of sealing assemblies including a first sealing member and a spaced-apart second sealing member, wherein the casing assembly defines a passage extending from a space defined between the first sealing member and the second sealing member to an exterior of the casing assembly; and a vent valve connected to the passage fluid, the vent valve opening at a predetermined fluid pressure.

[0017] In some examples, the second sealing member comprises a scraper seal.

[0018] In some examples, the compressor is a Roots-type compressor.

[0019] In some examples, a sound attenuation assembly is also provided, the sound attenuation assembly at least partially surrounding the outer periphery of the shell assembly, the sound attenuation assembly including a sound attenuation layer.

[0020] In some examples, the housing assembly and the sound attenuating layer are separated by an intermediate gap.

[0021] In some examples, the sound attenuating layer is a foam material.

[0022] In some examples, the sound attenuating layer includes multiple separate components.

[0023] Some of the other objects and advantages will be described in the following description, and some will be obvious from the description, or can be learned by practicing the teachings set forth herein. These objects and advantages will also be realized and obtained by the elements and combinations specifically pointed out in the appended claims. It should be understood that the foregoing summary of the invention and the following detailed description are only exemplary and illustrative, and do not limit the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view of a compressor assembly having features of an example of various aspects of the invention according to the principles of the present disclosure.

[0025] Figure 2 yes Figure 1 An exploded perspective view of the compressor assembly shown in FIG.

[0026] Figure 3yes Figure 1 A side cross-sectional view of an exemplary package housing of a compressor assembly is shown in FIG. , wherein the motor and compressor are schematically shown as solid blocks to facilitate viewing of the package housing.

[0027] Figure 4 yes Figure 1 A side elevation view of a compressor assembly is shown in FIG. 1 with the encapsulating housing removed.

[0028] Figure 5 yes Figure 1 A perspective view of a compressor and a first end of a packaging shell of a compressor assembly in FIG. 1 , wherein a vent valve is also installed, the vent valve extending from the compressor through the packaging shell to the outside of the compressor assembly.

[0029] Figure 6 yes Figure 5 A stereoscopic view of the compressor and the second end of the packaging shell.

[0030] Figure 7 yes Figure 5 A perspective view of a compressor with a compressor assembly in FIG.

[0031] Figure 8 yes Figure 7 A cross-sectional view of the compressor is shown in FIG.

[0032] Fig. 9 yes Figure 8 A partial view of the compressor shown in .

[0033] Fig.10 yes Figure 1 An enlarged view of a portion of the .

[0034] Fig.11 yes Figure 1 An enlarged view of a portion of the .

[0035] Fig.12 yes Figure 1 A perspective view of the encapsulated housing of the compressor shown in FIG.

[0036] Fig.13 yes Figure 1 A cross-sectional perspective view of the packaging shell shown in FIG.

[0037] Fig.14 yes Figure 7 A perspective view of the vent valve of the compressor shown in FIG.

[0038] Fig.15 Shows Figure 1 The first step in the assembly process of the compressor assembly.

[0039] Fig.16 Shows Figure 1The second step in the assembly process of the compressor assembly.

[0040] Fig.17 Shows Figure 1 The third step in the assembly process of the compressor assembly.

[0041] Fig.18 Shows Figure 1 The fourth step in the assembly process of the compressor assembly.

[0042] Fig.19 Shows Figure 1 The fifth step in the assembly process of the compressor assembly.

[0043] Fig. 20 Shows Figure 1 The sixth step in the assembly process of the compressor assembly.

[0044] Fig.21 Shows Figure 1 The seventh step in the assembly process of the compressor assembly.

[0045] Fig. 22 Shows Figure 1 The eighth step in the assembly process of the compressor assembly. DETAILED DESCRIPTION

[0046] The present disclosure relates to a compressor apparatus for use in a variety of applications. Among other things, the disclosed apparatus may be used in fuel cell applications (stationary and mobile) where the compressor supplies compressed air to a fuel cell stack.

[0047] refer to Figures 1 to 3 , a compressor assembly 10 is shown. In one aspect, the compressor assembly 10 includes a compressor or device 100 located within a packaging system 200, both of which are mounted to support plates 12, 14. The compressor assembly 10 is shown as also including an electric motor 16 coupled to the compressor 100. When the electric motor 16 is operated, the compressor 100 compresses air, which is delivered to, for example, a fuel cell air inlet via an outlet structure 18. The packaging system 200 is used to suppress or otherwise reduce the noise generated by the compressor 100 to the surrounding area. The electric motor 16 can be any desired type of electric motor and is therefore schematically shown herein. In addition, the compressor 100 disclosed herein is shown as a rotary device in the form of a Roots-type device. However, other types of devices may be used without departing from the concepts presented herein.

[0048] As in Figures 7 to 11As most easily observed in FIG. 1 , the compressor 100 can be provided with a main housing assembly 102, which defines an internal cavity or passage 104 extending between a first opening 106 and a second opening 108. In one example, the first opening 106 is an air inlet opening, and the second opening 108 is an air outlet opening. A pair of counter-rotating rotor assemblies 110, 112 are arranged in the internal cavity 104 of the main housing assembly 102. When the rotors 110, 112 rotate, the blades of the rotors abut against the inner side of the housing 102 to at least partially seal the working fluid, at which time, the working fluid is compressed only to the extent allowed by leakage. As configured, the compressor can increase the amount of intake air delivered to a power device (such as a fuel cell). In one example, the compressor can be a blower or supercharger of the type shown and described in U.S. Patent 7,488,164 (invention name "Rotor with optimized helix angle for Roots-type supercharger"). The entire contents of U.S. Patent 7,488,164 are incorporated herein by reference. Another example is provided by Patent Cooperation Treaty (PCT) International Publication No. WO 2013 / 148205, the entire contents of which are incorporated herein by reference.

[0049] In the example shown, the rotors 110, 112 have blades that are twisted or helically arranged along the length of the rotors 110, 112 (see, for example, Figure 8 ). This design differs from the construction of typical rotary screw devices and other similarly configured rotary equipment that have different numbers of blades (e.g., male rotors have "n" blades and female rotors have "n+1" blades). In addition, a distinguishing feature of compressor 100 is that rotors 110, 112 are identical, wherein rotors 110, 112 are relatively arranged such that when viewed from one axial end, the blades of one rotor twist clockwise and the blades of the meshing rotor twist counterclockwise. Other configurations are also possible, such as four-blade rotors.

[0050] In the example shown, the first opening 106 is arranged substantially orthogonal to the longitudinal axis X of the device 100 (see Figure 8 ), and the second opening 108 is arranged substantially parallel to the longitudinal axis X. Other opening configurations are also possible. In some examples, the working fluid is a compressible fluid, such as atmospheric air. In some applications, the device 100 is used as a compressor, such as for supercharger applications, wherein the rotors 110, 112 rotate to generate and deliver a flow of working fluid.

[0051] In one aspect, and as in Figure 8 As best seen in the drawings, each of the rotors 110 , 112 is mounted to a rotor shaft 114 , 116 , respectively.

[0052] In one aspect, timing gears 117, 118 are mounted to each shaft 114, 116, respectively. Timing gears 117, 118 mesh with each other to ensure that rotor assemblies 108, 110 rotate synchronously, thereby avoiding interference between rotor assemblies 108, 110. In the example shown, coupling member 119 is coupled to timing gear 117 by a plurality of pins 119a. The coupling member is configured with a receiving recess 119b to receive additional pins from an input or output device, thereby making it possible to transmit power to compressor 100 and / or transmit power from compressor 100 via an attached pulley, gear, etc. Other embodiments are also possible. For example, shaft 114 may be provided with an extension or additional length extending beyond timing gear 117, so that pulleys, gears or coupling members can be directly attached to shaft 114. In the example shown, three pins 119a and three receiving recesses 119b are provided. Other configurations are also possible, such as an arrangement of two pins and an arrangement of four pins.

[0053] Still reference Figure 8 , the device 100 may also be provided with bearing assemblies 120, 122, 124, 126 for supporting the shafts 114, 116 in a rotatable manner. In the example shown, the bearing assemblies 120, 122 are supported in the cavity of a bearing plate 128 mounted to the housing 102. The bearing plate 128 forms the interior cavity of the housing 102 and the end surface of the channel 104. The bearing assemblies 124, 126 are shown as being supported in a recessed or cavity portion of the housing 102. The bearing plate 128, when removed, provides an opening through which the rotor assemblies 110, 112 can be installed to and removed from the interior of the housing 102.

[0054] The device 100 may also be provided with sealing assemblies 130, 132, which are respectively mounted within the cavities 128a, 128b of the support plate 128 to ensure that lubricating fluid associated with the timing gears 117, 118 does not leak into the passage 104. Fig.10 In the example shown in , the sealing assemblies 130, 132 each include a first seal 130a, 132a arranged in series and a second seal 130b, 132b spaced apart. Each of the seals 130a, 130b, 132a, 132b provides sealing contact between the corresponding shaft 114, 116 and the cavity 128a, 128b. In one aspect, the seals 130b, 132b are provided with a wiper-type seal that is offset in the direction toward the seals 130a, 132a, which creates a greater resistance to prevent the fluid from flowing from the cavity 128a, 128b into the channel 104.

[0055] Still reference Fig.10In some implementations, the space between the seals 130a and 130b and the space between the seals 132a and 132b are open to the atmosphere to reduce the possibility of lubricating oil associated with the timing gear being transmitted and leaking into the passage 104. To facilitate such ventilation, a first passage 128c extending between the cavities 128a and 128b is provided in the support plate 128, while a second passage 128d extending from the cavity 128b to the exterior of the housing 102 is provided. A vent valve 250 is installed through the opening 102a in the housing 102 and extends to the passage 128d. The vent valve 250 is configured so that the valve opens at a predetermined pressure to release the pressure in the cavities 128a and 128b and on the seals 130b and 132b, thereby minimizing the chance of fluid leaking into the passage 104 through the seals 130b and 132b. In the example shown, the vent valve 250 is a dual vent valve.

[0056] The compressor 100 may also include other components not shown in the drawings or discussed herein, the inclusion of which is readily apparent to those skilled in the art. For example, it is contemplated that the compressor 100 includes a cover mounted to the support plate to cover the timing gears 117 , 118 .

[0057] As previously mentioned, the compressor assembly 10 may include a packaging system 200 that defines an interior cavity 201 within which the compressor 100 is disposed (see FIG. Figure 8 ). The packaging system 200 is configured to reduce the transmission of noise generated by the compressor 100. In one aspect, the packaging system 200 can be characterized as a sound attenuating shell, which includes an outer layer 210 and an inner layer 220 that absorbs sound. In some examples, the outer layer 210 is a sound reflecting material. In some examples, the outer layer 210 is a sound absorbing layer. Either the inner layer and the outer layer can have sound absorbing properties and sound reflecting properties. In some examples, the inner layer is relatively more sound absorbing than the outer layer, and the outer layer is relatively more sound reflecting than the inner layer.

[0058] In some examples, the outer layer 210 is made of a metal material (such as a bent metal sheet) and can be characterized as a protective or outer shell. As shown, the outer layer 210 is provided with a peripheral wall 212 extending between flanges 214, 216, which can be used to mount the outer layer 210 to the support plates 12, 14 via fasteners.

[0059] In some examples, the inner layer 220 is made of a sound attenuating material such as foam or fiberglass material, and the inner layer can be characterized as a sound attenuating layer. In some examples, the inner layer 220 is made of one or more foam sheets having a thickness in the range of 10 mm to 15 mm. In the example shown, the inner layer 220 includes a peripheral wall 222 extending between a first end wall 224 and a second end wall 226. Each of the first end wall 224 and the second end wall 226 is provided with an opening 224a, 226a. As shown in Figure 5 , Figure 6 and Figure 8 As best seen in the example, the openings 224a, 226a have a profile that matches the outer periphery of the end of the housing 102, such that the outer periphery of the housing 102 is completely encapsulated by the inner layer 220, thereby causing the opening 108 to also be encapsulated within the inner layer 220 and the outer layer 210, and only the axial end face of the housing 102 is not covered by the inner layer 220. The end faces of the housing 102 are mounted to the support plates 12, 14. In the example shown, the peripheral wall 222 is spaced from the opening 108, such that an internal volume portion for accommodating the outlet structure 18 is formed between the inner layer 220 and the opening 108. In one aspect, there is a gap, an intermediate space or volume portion or an empty space 201a between the inner layer 220 and the radial outer surface of the compressor 100 and the radial outer surface of the outlet structure 18. Such an intermediate presence can help to further reduce the noise transmitted from the compressor 10 compared to arranging the inner layer 220 in close proximity to the housing 102.

[0060] In one aspect, the outer layer 210 is provided with an opening 218 in the peripheral wall 212, while the inner layer 220 is provided with an opening 228 in the peripheral wall 222. In the example shown, the openings 218, 228 are coaxially aligned and face the opening 108 in the housing 102. In one example, a compressed fluid (such as compressed air) leaves the opening 108 of the housing 102 and enters the outlet structure 18, which is arranged in a portion of the interior cavity 104 between the peripheral wall 222 and the opening 108. Reverse flow is also possible. In the example shown, a gasket or seal 219 can be provided at the location of the openings 218, 228 so that a seal can be formed with the outlet structure 18 (see Fig.18 In some examples, the outlet structure 18 is in fluid communication with an air inlet of the fuel cell. The outer layer 210 and the inner layer 220 are also provided with openings 217, 229, respectively, through which the vent valve 250 extends.

[0061] As in Figure 2As most easily observed in the example, the packaging system 200 can be configured as multiple parts that can be assembled around the compressor 100. In the example shown, the outer layer 210 is provided with a first portion 210a and a second portion 210b that cooperate, and the two parts together form an entire perimeter around the inner layer 220. The inner layer 220 is shown as being provided with a first portion 220a, a second portion 220b, and a third portion 220c that cooperate. In the example shown, each of the first portion 220a, the second portion 220b, and the third portion 220c defines a portion of the peripheral wall 222, wherein the first portion 220a also defines an end wall 224, and the second portion 220b also defines an end wall 226. In one feature, the first portion 220a and the second portion 220b are configured to be L-shaped, while the third portion 220c is configured to be U-shaped. Other configurations are also possible.

[0062] refer to Figures 15 to 22 , shows the assembly process of the compressor assembly 10. In the first step, as Fig.15 As shown in , the first portion 220a of the inner layer is mounted or otherwise fixed to the support plate 12. In a second step, as shown in Fig.16 As shown in FIG. 1 , the compressor 10 and the outlet structure 18 are mounted to the support plate 12. In the third step, as shown in FIG. Fig.17 As shown in FIG. 1 , the motor 16 is mounted to the support plate 12. In the fourth step, as shown in FIG. Fig.18 As shown in FIG. 1 , a gasket 219 is installed around the outlet structure 18. In the fifth step, as shown in FIG. Fig.19 As shown in FIG. 1 , the first part 210a and the second part 210b are mounted to the support plate 12. In the sixth step, as shown in FIG. Fig. 20 As shown in FIG. 1 , the second portion 220 b is inserted between the compressor 100 and the first portion 210 a and the second portion 210 b. In the seventh step, as shown in FIG. Fig.21 As shown in FIG. 1 , the third portion 220 c is inserted between the compressor 100 and the first portion 210 a and the second portion 210 b. In the eighth step, as shown in FIG. Fig. 22 As shown in FIG. 1 , the compressor 100 and the first and second parts 210 a and 210 b are mounted to the support plate 14 .

[0063] In general, for a compressor of the type disclosed herein, the current source noise level when the compressor is operated at about 20,000 rpm with a pressure ratio of 2.2 has a maximum sound output level of about 95 decibels (dB) at a distance of 1 meter. Using the sound attenuation packaging system of the present disclosure, it is expected that the noise level at the same distance can be reduced to a level of about 75 dB, thereby achieving a noise reduction effect of 20 dB.

[0064] Examples of the present disclosure may be described according to the following aspects.

[0065] Aspect 1: A compressor assembly, comprising:

[0066] a) Compressor, including:

[0067] i) a main housing having an inlet and an outlet;

[0068] ii) a pair of rotors disposed within the interior cavity, each rotor of the pair of rotors having a plurality of blades; and

[0069] b) a sound attenuating assembly at least partially surrounding an outer periphery of the main housing, the sound attenuating assembly comprising a sound attenuating layer.

[0070] Aspect 2: The compressor assembly of aspect 1, wherein the main housing and the sound attenuation layer are separated by an intermediate gap.

[0071] Aspect 3: The compressor assembly of aspect 1, wherein the sound attenuating layer is a foam material.

[0072] Aspect 4: The compressor assembly of aspect 1, wherein the sound attenuating layer comprises a plurality of separate components.

[0073] Aspect 5: The compressor assembly of aspect 1, wherein the sound attenuating assembly comprises an outer layer surrounding the sound attenuating layer.

[0074] Aspect 6: The compressor assembly according to aspect 5, wherein the outer layer is made of a metal sheet.

[0075] Aspect 7: The compressor assembly according to aspect 5, wherein the outer layer is formed from a plurality of separate components.

[0076] Aspect 8: A sound attenuation assembly for a compressor, the sound attenuation assembly comprising:

[0077] a) Outer layer;

[0078] b) an inner layer disposed within the outer layer, the inner layer being made of a sound attenuating material, the inner layer defining a peripheral wall extending between a first end wall and a second end wall, the first end wall including a first opening for surrounding a first end of the compressor so that a drive mechanism can be connected to the compressor, the second end wall including a second opening for surrounding a second end of the compressor having an air inlet opening, the peripheral wall having an opening through which an outlet of the compressor can extend.

[0079] Aspect 9: The sound attenuating assembly of aspect 8, wherein the sound attenuating material is a foam material.

[0080] Aspect 10: The sound attenuating assembly of aspect 8, wherein the inner layer comprises a plurality of separate components.

[0081] Aspect 11: The sound attenuating assembly of aspect 8, wherein the outer layer is made of a material different from the sound attenuating material.

[0082] Aspect 12: The sound attenuation assembly of aspect 11, wherein the outer layer is made of sheet metal.

[0083] Aspect 13: The sound attenuation assembly of aspect 8, wherein the outer layer is formed from a plurality of separate components.

[0084] Aspect 14: A compressor comprising:

[0085] a) a housing assembly having a first opening and a second opening in fluid communication with the interior cavity;

[0086] b) a pair of rotors disposed within the interior cavity, each rotor of the pair of rotors having a plurality of blades;

[0087] c) a pair of shafts supporting the pair of rotors;

[0088] d) a pair of seal assemblies providing a seal between the pair of shafts and the housing assembly, each seal assembly of the pair of seal assemblies comprising a first seal member and a spaced-apart second seal member, wherein the housing assembly defines a passage extending from a space defined between the first seal member and the second seal member to an exterior of the housing assembly; and

[0089] e) a vent valve connected to the channel fluid, the vent valve opening at a predetermined fluid pressure.

[0090] Aspect 15: The compressor according to aspect 14, wherein the second sealing member has a scraper seal.

[0091] Aspect 16: The compressor according to Aspect 14, wherein the compressor is a Roots-type compressor.

[0092] Aspect 17: The compressor according to aspect 14, further comprising a sound attenuation assembly at least partially surrounding an outer periphery of the housing assembly, the sound attenuation assembly comprising a sound attenuation layer.

[0093] Aspect 18: The compressor assembly of aspect 17, wherein the housing assembly and the sound attenuating layer are separated by an intermediate gap.

[0094] Aspect 19: The compressor assembly of aspect 17, wherein the sound attenuating layer is a foam material.

[0095] Aspect 20: The compressor assembly of aspect 17, wherein the sound attenuating layer comprises a plurality of separate components.

[0096] Other implementations will be apparent to those skilled in the art from consideration and practice of the examples and teachings presented herein. It is intended that the specification and embodiments be considered exemplary only, with the true scope of the invention being indicated by the following claims.

Claims

1. A compressor assembly, comprising: a) Compressor, including: i. A main housing having an inlet and an outlet; ii. a pair of rotors disposed within the internal cavity, each rotor of the pair of rotors having a plurality of blades; and b) a sound attenuating assembly at least partially surrounding an outer periphery of the main housing, the sound attenuating assembly comprising a sound attenuating layer.

2. The compressor assembly according to claim 1, wherein: The main housing and the sound attenuating layer are separated by an intermediate gap.

3. The compressor assembly according to claim 1, wherein: The sound attenuating layer is a foam material.

4. The compressor assembly according to claim 1, wherein: The sound attenuating layer comprises a plurality of separate components.

5. The compressor assembly of claim 1, wherein: The sound attenuating assembly includes an outer layer surrounding the sound attenuating layer.

6. The compressor assembly according to claim 5, wherein: The outer layer is made of metal sheet.

7. The compressor assembly according to claim 5, wherein: The outer layer is formed from a plurality of separate components.

8. A sound attenuation assembly for a compressor, the sound attenuation assembly comprising: a) Outer layer; b) an inner layer disposed within the outer layer, the inner layer being made of a sound attenuating material, the inner layer defining a peripheral wall extending between a first end wall and a second end wall, the first end wall including a first opening for surrounding a first end of the compressor so that a drive mechanism can be connected to the compressor, the second end wall including a second opening for surrounding a second end of the compressor having an air inlet opening, the peripheral wall having an opening through which an outlet of the compressor can extend.

9. The sound attenuation assembly of claim 8, wherein: The sound attenuating material is a foam material.

10. The sound attenuation assembly of claim 8, wherein: The inner layer comprises a plurality of separate components.

11. The sound attenuation assembly of claim 8, wherein: The outer layer is made of a material different from the sound attenuating material.

12. The sound attenuation assembly of claim 11, wherein: The outer layer is made of metal sheet.

13. The sound attenuation assembly of claim 8, wherein: The outer layer is formed from a plurality of separate components.

14. A compressor, comprising: a) a housing assembly having a first opening and a second opening in fluid communication with the interior cavity; b) a pair of rotors disposed within the interior cavity, each rotor of the pair of rotors having a plurality of blades; c) a pair of shafts supporting the pair of rotors; d) a pair of seal assemblies providing a seal between the pair of shafts and the housing assembly, each of the pair of seal assemblies comprising a first seal member and a spaced-apart second seal member, wherein the housing assembly defines a passage extending from a space defined between the first seal member and the second seal member to an exterior of the housing assembly; as well as e) a vent valve in fluid communication with the passage, the vent valve opening at a predetermined fluid pressure.

15. The compressor according to claim 14, wherein: The second sealing member has a scraper seal.

16. The compressor according to claim 14, wherein: The compressor is a Roots compressor.

17. The compressor of claim 14, further comprising a sound attenuation assembly at least partially surrounding an outer perimeter of the housing assembly, the sound attenuation assembly comprising a sound attenuating layer.

18. The compressor assembly of claim 17, wherein: The housing assembly and the sound attenuating layer are separated by an intermediate gap.

19. The compressor assembly of claim 17, wherein: The sound attenuating layer is a foam material.

20. The compressor assembly of claim 17, wherein: The sound attenuating layer comprises a plurality of separate components.

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