Positive pressure air purification device for crankcase ventilation system

Abstract

Apparatuses, systems, and methods are disclosed that include an apparatus of a ventilation system for supplying air to a crankcase of an internal combustion engine. The apparatus may optionally include a housing, an air filter, a cover, and a pressure relief valve. The housing may form a cavity and have an inlet and an outlet therein. The inlet communicates with the cavity and is offset from the central axis of the housing. An air filter may be received by the cavity. The outer circumference of the air filter may be oriented at an angle substantially tangential to the inlet. The cover may be attachable to and removable from the housing so as to selectively access the air filter. A pressure relief valve is coupled to the housing and in fluid communication with the cavity.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine, such as an internal combustion engine used in a vehicle or stationary power generation. More particularly, the present invention relates to an air cleaning device for a crankcase ventilation system of an internal combustion engine. Background Art

[0002] Machinery, such as agricultural, industrial, construction or other heavy machinery can be propelled by an internal combustion engine. The internal combustion engine can be used for other purposes, such as for power generation. The internal combustion engine burns a mixture of air and fuel in the cylinder, thereby generating a driving torque and power. The internal combustion engine generally includes a crankcase to provide a housing for the engine crankshaft. A portion of the combustion gases (called "blow-by") can leave the combustion chamber through the piston and enter an undesirable area of ​​the engine, such as the crankcase. The blow-by may contain hydrogen (explosive gas) and potentially corrosive chemicals such as hydrogen sulfide and hydrogen sulfide byproducts such as sulfur dioxide. In rare cases, unburned fuel and / or explosive gases may accumulate in the engine, such as in the crankcase. If the explosive gases and corrosive chemicals cannot be properly mitigated using a crankcase ventilation system, the explosive gases and corrosive chemicals may cause harmful side effects, such as explosions or corrosion. Crankcase ventilation systems are known in internal combustion engines for discharging blow-by gases in the crankcase. For example, U.S. Patent Nos. 3,589,108, 4,653,457, 4,995,891, 9,909,470, and 10,875,445 disclose examples of crankcase ventilation systems. However, these patents do not provide air purification devices in the manner disclosed herein. Summary of the invention

[0003] In an example according to the invention, a device for a ventilation system for supplying air to a crankcase of an internal combustion engine is provided. The device optionally includes a housing, an air filter, a cover and a pressure reducing valve. The housing may form a cavity and have an inlet and an outlet therein. The inlet is communicated with the cavity and deviates from the central axis of the housing. The air filter may be received by the cavity. The outer circumference of the air filter may be oriented at an angle substantially tangential to the inlet. The cover may be attachable to the housing and removable from the housing to selectively approach the air filter. The pressure reducing valve is coupled to the housing and is in fluid communication with the cavity.

[0004] In another example according to the present invention, a method of maintaining an air filter is disclosed, the air filter being used to supply air to a crankcase of an internal combustion engine. The method may include: providing a housing forming a cavity and having an inlet and an outlet therein; positioning the air filter within the cavity and at least partially retained by the housing; providing a cover sealed to the housing at at least two locations; and removing the cover from the housing to access the air filter within the cavity.

[0005] In yet another example according to the invention, a ventilation system for a crankcase of an internal combustion engine is disclosed. The ventilation system may optionally include: a low pressure, high mass flow air delivery system; an apparatus configured to receive air from a blower, a pressure reducing valve, and a heat exchanger. The apparatus may optionally include: a housing forming a cavity and having an inlet and an outlet for receiving air therein, an air filter received by the cavity; and a cover attachable to the housing and removable from the housing for selective access to the air filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the accompanying drawings, which are not necessarily drawn to scale, the same numerals may describe similar components in different views. Similar numerals with different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments discussed in this document by way of example and not limitation.

[0007] Figure 1 is a highly schematic illustration of an example internal combustion engine including a crankcase and a ventilation system for the crankcase according to an example of the present invention.

[0008] Figure 2 is a perspective view of a ventilation system for a crankcase including an air purification device according to an example of the present invention.

[0009] Figure 3 According to an example of the present invention Figure 2 A plan view of the side of the ventilation system's air purification equipment.

[0010] Figure 4 According to an example of the present invention Figure 3 A cross-sectional view of an air purification device.

[0011] Figure 4A According to an example of the present invention Figure 4 An enlarged cross-sectional view of a portion of a cover and housing of an air cleaning device.

[0012] Figure 5 is based on Figure 3-4A A perspective view of an exterior portion of a port of an air purification device having a pressure reducing valve according to an example of the present invention. DETAILED DESCRIPTION

[0013] Examples according to the present invention relate to equipment for purifying air used with a crankcase ventilation system, which is used to supply purified air to an internal combustion engine to dilute unburned smoke, blow-by components and / or atomized oil within the internal combustion engine. Methods for servicing such equipment are also discussed. Examples of the present invention are now described with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present invention, application or use. The described examples set forth specific components, devices and methods to provide an understanding of embodiments of the present invention. It will be apparent to those skilled in the art that specific details need not be adopted and that the examples may be implemented in many different forms. Therefore, the embodiments provided should not be interpreted as limiting the scope of the claims.

[0014] As used herein, the terms "comprises," "comprising," "having," "containing," or other variations thereof are intended to encompass a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, relative terms (e.g., "about," "substantially," "typically," and "substantially," etc.) are used to indicate possible variations of ±15% in the stated values.

[0015] Figure 1 An internal combustion engine 100 (sometimes referred to herein as an "engine" for simplicity) according to the present invention is depicted in a highly schematic manner. The engine 100 can be used for power generation, such as for propulsion of vehicles or other machinery or for stationary power generation. The engine 100 can include various power generation platforms and can use fuels including, for example, gasoline, gaseous fuels, diesel, or mixtures thereof. Stationary engines can be used to drive stationary equipment such as pumps, generators, mills, or factory equipment. In one embodiment, the engine 100 can be used for power generation in landfill applications. In this way, the engine 100 can use gaseous fuels. As used herein, "gaseous fuel" may include fuel supplied to the engine 100 in a gaseous form, and may include, for example, propane, natural gas, gases related to natural gas such as biogas, landfill gas, carbon monoxide, hydrogen, hydrogen sulfide, or mixtures thereof. The fuel may have different purity levels. As used herein, natural gas refers to pure and relatively impure forms with different amounts of methane and other components. It should be understood that the present invention may be applied to any number of piston-cylinder arrangements, including but not limited to V-type engines, in-line engines, and horizontally opposed engines, as well as overhead cam and cam-in-block configurations.

[0016] In some applications, the internal combustion engine disclosed herein is intended for gas compression. The internal combustion engine can employ a low pressure fuel delivery system, wherein the fuel is introduced at the turbocharger / compressor inlet. Thus, the fuel can be mixed all the way through the engine. The internal combustion engine 100 can be used for stationary applications as described above, but can also be used for vehicles and machinery associated with various industries, including, for example, construction, agriculture, forestry, transportation, material handling, waste management, and the like.

[0017] The engine 100 may include an on-engine or off-engine (or partially on-engine and partially off-engine) ventilation system 102 for a crankcase 104. The ventilation system 102 may include a low-pressure, high-mass-flow air delivery system 106, an air cleaning device 108, a heat exchanger 110, and passages 112A, 112B, and 112C.

[0018] Passages 112A, 112B, and 112C allow fluid communication between the low pressure, high mass flow air delivery system 106, the air purification device 108, the heat exchanger 110, and the crankcase 104. Figure 1 , but it should be appreciated that the ventilation system 102 may include valves or other regulators that are configured to prevent reverse flow when the pressure along passages 112B and 112C or within the air purification device 108 and / or heat exchanger 110 is lower than the pressure within the crankcase 104. Figure 5 An example of a pressure reducing valve 160 for an air cleaning device 108 and a ventilation system 102 is shown. However, in all examples, the valve or regulator does not require an operating standard as specified by the load and pressure level. The terms "channel", "multiple channels", "passage", "multiple passages", "line" or "multiple lines" used herein should be interpreted broadly. These terms can be features defined by the various components of the engine shown in the drawings, or can be formed by additional components known in the art (e.g., hoses, pipes, conduits, manifolds, cavities, etc.).

[0019] exist Figure 1 In the example of , components of the ventilation system 102, such as the air purification device 108 and the heat exchanger 110, may be mounted to the engine 100. However, it is contemplated that these components may be separate from the engine 100 (e.g., not mounted thereto except via the passage 112C). The ventilation system 102 or some of its components may be part of the original manufacture of the engine 100, or may be a modified system added to the engine 100 during maintenance, upgrades, etc. The ventilation system 102 may be in fluid communication with the crankcase 104, for example, via passages 112A, 112B, and 112C. The ventilation system 102 may be configured to supply ambient air or air from a pressurized source to the crankcase 104.

[0020] Air for the ventilation system 102 can be collected at the inlet to the low-pressure, high-mass flow air delivery system 106 (e.g., a blower, fan or similar air power device) and passed along the passage 112A to the air purification device 108 so as to be properly purified, for example, by passing through an air filter. The air for the inlet can be obtained from the atmosphere or other sources. Then, the air can flow from the air purification device 108 along the passage 112B to the heat exchanger 110, in which the air is heated or cooled to the desired temperature range. Then, the air is passed to the engine 100 along the passage 112C with a desired pressure range and a desired mass flow rate range. For example, the desired mass flow rate range can be between about 0.002kg / hr*bkW and 1.02kg / hr*bkW. However, other ranges of the desired mass flow rate range are also expected. The mass flow rate range should be sufficient to keep the volatiles in sensitive areas such as the crankcase 104 below the lower explosion limit (usually the fuel volume percentage is less than 5%). The mass flow rate should not be too large to avoid the possibility of high crankcase pressure.

[0021] The low-pressure, high-mass-flow air delivery system 106 can be part of a positive pressure system that can supply air to the crankcase 104 at a desired pressure range. The heat exchanger 110 can be an aftercooler or another type of air-to-air or liquid-to-air heat exchanger, such as a jacket heat exchanger known in the art. The heat exchanger 110 can be configured to receive air and heat or cool it to a desired temperature range. For example, the desired temperature range can be between about 80 degrees Celsius and about 120 degrees Celsius. The heat exchanger is not considered in all examples. Compressed air is passed from the heat exchanger 110 along passage 112C, for example, via an intake manifold or other suitable connection to the crankcase 104.

[0022] Devices such as breathers (not shown) may be directly or indirectly coupled to the engine block and may be in fluid communication with the crankcase 104. Each breather may include a mechanism for separating oil droplets and oil mist from the blow-by gases so as to prevent the oil droplets and oil mist contained in the blow-by gases from being removed along the flow of the blow-by gases. For example, the breather may include one or more separation mechanisms, such as an oil separation valve, a splash plate, a serpentine passage, a net or other obstruction. The breather may be an outlet that allows smoke, blow-by gas components and / or atomized oil to pass through to the atmosphere or another location such as away from the engine 100.

[0023] Figure 2 1 is a perspective view of some components of ventilation system 102, including air purification equipment 108, heat exchanger 110 and channels 112B and 112C. Low pressure, high mass flow air delivery system 106 and channel 112A ( Figure 1 )exist Figure 2Mounting devices 114A, 114B and 114C (eg, flanges and / or brackets) may be provided for mounting the air purification device 108, the heat exchanger 110 and the passage 112C to the engine 100 ( Figure 1 ) or other objects. Restriction sensor 115 can be coupled to air purification device 108 or duct 112. Restriction sensor 115 can be used to measure the pressure relative to the inlet of air delivery system 106 or relative to the pressure of the surrounding environment in order to determine / measure the restriction of the filter through air purification device 108.

[0024] Figure 3 Air purification device 108 is shown in greater detail. Purification device 108 may include housing 116, cover 118, and fasteners 120. Housing 116 may include outer circumference 122, inlet 124, outlet 126, and one or more ports 128A, 128B, 128C, and 128D.

[0025] The housing 116 may be formed of a metal or metal alloy such as aluminum, steel, etc. For example, the housing 116 may have a one-piece unitary structure. The cover 118 is configured to be coupled to the housing 116 at the opening formed thereby. The fastener 120 may secure the cover 118 to the housing 116. The cover 118 may be formed of a material similar to or identical to that of the housing 116.

[0026] The housing 116 may be substantially cylindrical with an outer circumference 122 and a hollow interior (discussed later). The inlet 124 may be configured to communicate directly or indirectly with the passage 112A ( Figure 1 ) is coupled to receive air and may communicate with the interior of the housing 116. The housing 116 may have a central axis CL. The outlet 126 may be substantially aligned with the central axis CL, while the inlet 124 may be offset from the central axis CL.

[0027] In addition to the inlet 124 and outlet 126 that pass through the housing 116 to enter the hollow interior of the housing 116, one or more ports 128A, 128B, 128C, and 128D may provide access to the interior of the housing 116. One or more ports 128A, 128B, 128C, and 128D may be configured to provide access for devices such as sensors, valves, gauges, etc. For example, port 128D may provide access at (or adjacent to) outlet 126 and may be connected to a restriction sensor 115 ( Figure 2 ) to provide access to a restriction sensor 115 to determine / measure the restriction across the air filter (see Figure 4 ).

[0028] Figure 4is a cross-section of air purification device 108 showing additional features and components inside housing 116 , such as air filter 130 . Figure 4 The housing 116, cover 118, fasteners 120, outer circumference 122, and outlet 126 are shown as previously described. Figure 4 As shown, the housing 116 may include a cavity 132 , a groove 134 , and an internal flange 136 .

[0029] The cavity 132 can be formed by the inner side of the housing 116. The inner side can further form a groove 134 and an inner flange 136. The cavity 132 can be configured to receive an air filter 130. The air filter 130 can have a substantially cylindrical shape with a hollow interior. The air filter 130 can include a fiber or porous material for removing solid particles (e.g., dust, pollen, mold, bacteria, etc.). For example, the air filter 130 can include a paper filter, a foam filter, a cotton filter, etc. The air filter 130 can be positioned in the cavity 132 maintained by abutting contact with the cover 118, the groove 134 and / or the inner flange 136. The air filter 130 can include, for example Air filter type 2W4246.

[0030] The air filter 130 can have an outer circumference 138, seals 140A and 140B, an inner circumference 142, and an inner cavity 144. The housing 116 can be spaced apart from the outer circumference 138 of the air filter 130 by at least a majority of the surface area of ​​the outer circumference 138. The seal 140A can be on an end of the air filter 130 opposite to the seal 140B. The outer circumference 138 can extend between the seal 140A and the seal 140B. The seal 140A can be engaged and abutted by the cover 118. The seal 140B can be engaged and abutted by the groove 134. The inner circumference 142 can form an inner cavity 144. The inner circumference 142 can engage with the inner flange 136.

[0031] like Figure 4 As shown, the inner flange 136 can protrude into the cavity 132. The inner flange 136 can be located adjacent to the outlet 126, and the outlet 126 can be substantially aligned with the central axis CL of the housing 116. The inner cavity 144 can be in fluid communication with the outlet 126. The cover 118 can be selectively removable from the housing 116 and connected to the housing 116. The cover 118 can include a handle 146 to facilitate removal to access the air filter 130 for maintenance, such as replacement.

[0032] like Figure 4 As shown, the outer portion 133 of the cavity 132 can be positioned around all or part of the outer circumference 138 of the air filter 130. This can allow air to flow around at least a portion of the outer circumference 138 before passing through the air filter 130 to the inner cavity 144. Now returning to Figure 4, the inlet 124 can be configured (positioned, shaped, etc.) relative to the air filter 130 so that the outer circumference 138 of the air filter 130 is oriented at an angle that is substantially tangential to the central axis CL2 of the inlet 124. This arrangement can allow air to circulate from the inlet 124 around at least a portion of the outer circumference 138 before the air passes through the air filter 130 to the outlet 126. In other words, the outer portion 133 can extend circumferentially around the entirety or substantially the entirety of the outer circumference 138 of the air filter 130. This can allow air to flow from the inlet 124 around at least a portion of the outer circumference 138 before passing through the air filter 130.

[0033] Figure 4A 1 is an enlarged view of a portion of the housing 116 and cover 118 of the air purification device 108. The housing 116 may include a first groove 148. The cover 118 may include a flange 150, a body 152, and a second groove 154.

[0034] like Figure 4A As shown, the first O-ring 156 can be positioned in the first groove 148, and the second O-ring 158 can be positioned in the second groove 154. When the cover 118 is positioned downwardly over the opening of the housing 116 and coupled to the housing 116 via the fastener 120, the first O-ring 156 and the second O-ring 158 can together provide a single seal for the cover 118 and the housing 116. Figure 4A As shown, the first O-ring 156 can be disposed at a substantially 90 degree angle to the second O-ring 158. This may be due to the shape of the cover 118 relative to the shape of the housing 116. More specifically, the cover 118 includes a flange 150 that projects outwardly from the body 152 and seals with the first O-ring 156. The body 152 extends in a direction substantially transverse to the flange 150 and seals with the second O-ring 158. The individual seals created by the apparatus discussed are robust and can withstand, for example, the cavity 132 ( Figure 4 ) within a pressure range of -35kPa-g to +35kPa-g.

[0035] Figure 5 1 and 12. A portion of the housing 116 of the air purification device 108 is shown including one or more ports 128A. A pressure relief valve 160 is located in the port 128A and is in contact with the interior of the housing 116, particularly the cavity 132 ( Figure 4A ) is connected. The pressure reducing valve 160 may be a ventilation system 102 ( Figure 1 and 2 ) portion. The pressure relief valve 160 may include a poppet valve core configured to allow the cavity 132 ( Figure 4) ventilation. According to one example, the pressure relief valve 160 can have an actuation pressure of 2.5±0.5 psi. However, other valves with other actuation pressures are contemplated. As discussed, if desired, one or more ports 128A (128B, 128C, and 128D not shown) can be used with other valves, gauges, and / or sensors.

[0036] Industrial Applicability

[0037] In operation, the engine 100 can be configured to burn fuel to generate power. Although usually effective, a small portion of the blowby may escape the combustion chamber through the piston and enter the undesirable area of ​​the engine, such as the crankcase 104. As used herein, blowby may include leakage of air, fuel, combustion gases and / or mixtures thereof. The air supplied by the ventilation system 102 can be used to ventilate the crankcase 104 and other components. This ventilation can dilute unburned fuel, explosive gases and / or volatiles (such as those found in the blowby and / or fuel) to below the lower explosion limit, thereby preventing or reducing the possibility of explosion in the engine 100. In addition, for example, dilution can reduce corrosion due to reducing the concentration of hydrogen sulfide.

[0038] The present invention contemplates that the ventilation system 102 can be in fluid communication with the crankcase 104 and can supply air to the crankcase 104 as a positive pressure system. The air supplied to the crankcase 104 and other components of the engine 100 can have a desired temperature range, a desired pressure range, and a desired mass flow rate range. As described above, the air supplied by the ventilation system 102 can be used to ventilate or purge the crankcase 104 and other components.

[0039] Deviations from the desired pressure range, such as overpressure events or backup gas within the air purification device 108 and / or heat exchanger 110, may cause damage to the passages 112B and 112C and the crankcase 104. For example, if the air filter 130 becomes caked, blocked, or otherwise impaired so that it no longer functions properly, such an overpressure event may occur. The air purification device 108 of the present invention provides several solutions to avoid or mitigate overpressure at the air purification device 108.

[0040] Air entering the air purification device 108 at the inlet 124 of the housing 116 is introduced substantially tangentially to the outer circumference 138 of the air filter 130. In other words, the outer circumference 138 of the air filter 130 is oriented at an angle substantially tangential to the inlet 124. This arrangement and the outer portion 133 of the cavity 132 including the entire or most of the outer circumference 138 allow the air to circulate from the inlet 124 around at least a portion of the outer circumference 138 before the air passes through the air filter 130 to reach the outlet 126. This arrangement avoids directing the air from the inlet directly to only a small area of ​​the outer circumference 138 of the air filter 130, which will clog / cake more quickly than spreading the incoming air over a larger surface area of ​​the outer circumference 138.

[0041] In addition, the air cleaning device 108 may include a pressure reducing valve 160, which can be actuated if an undesirable pressure is formed in the cavity 132. Overpressure can be released via the pressure reducing valve 160, and can leave the air cleaning device 108 via one or more ports 128A, 128B and / or 128C. It is advantageous to use the pressure reducing valve 160 to provide sufficient mass flow rate to keep the smoke in the crankcase 104 below the lower explosion limit while avoiding undesirable high pressure in the crankcase 104. The high pressure in the crankcase 104 can lead to pressure spikes in the engine 100 and other undesirable and potentially destructive pressure-related results. A sensor or meter can be used with one or more ports 128A, 128B and / or 128C, and can provide a measurement of the pressure drop across the air filter 130, which can allow a better understanding of when the air filter 130 needs to be maintained. Maintenance can include removing the air filter 130 from the cavity 132, inserting a second air filter into the cavity and sealing the cover with a housing at least two positions. Positioning the air filter 130 in the cavity 132 and at least partially held by the housing can include aligning the air filter with the groove 134 and the internal flange 136 of the housing 116 and inserting the air filter into the groove of the housing. The air purification device 108 can be an air filter in the cavity and at least partially held by the housing 116. The cover 118 can be sealed to the housing 116 at least in two positions. The cover 118 can be removed from the housing 116 to access the air filter 130 in the cavity 132. Positioning the air filter 130 in the cavity 132 can include positioning the air filter so that the outer circumference of the air filter is oriented at an angle substantially tangential to the inlet 124, as previously discussed.

[0042] The air cleaning device 108 further includes a housing 116 and a cover 118 having at least two grooves (148 and 154) and at least two O-rings (156 and 158). These allow the cover 118 to have additional sealing capabilities relative to the housing 116. In addition, the air filter 130 itself is sealed with the cover 118 and / or sealed in the housing 116 by the groove 134. This additional sealing of the cover 118 and the housing 116 and / or this additional sealing of the air filter 130 and the housing 116 and the cover 118 can provide a desired seal in the case where the return gas enters the air cleaning device 108. This return gas may contain hydrogen / hydrogen sulfide, which may be explosive and / or corrosive. The escape of this gas from the ventilation system 102 is undesirable.

[0043] The foregoing detailed description is intended to be illustrative rather than limiting. The scope of the present invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A device for a ventilation system for supplying air to a crankcase of an internal combustion engine, the device comprising: a housing forming a cavity and having an inlet and an outlet therein, wherein the inlet communicates with the cavity and is offset from a central axis of the housing, an air filter received by the cavity, wherein an outer circumference of the air filter is oriented at an angle substantially tangential to the inlet; a cover attachable to and removable from the housing to provide selective access to the air filter; as well as A pressure relief valve is coupled to the housing and is in fluid communication with the cavity.

2. The apparatus of claim 1 , wherein the pressure relief valve passes through a port in the housing, wherein the air filter has an interior cavity, and wherein the outlet is in fluid communication with the interior cavity and is substantially aligned with a central axis of the housing.

3. The apparatus of any one of claims 1-2, wherein the air filter is retained within the cavity by at least one of a groove of the housing and a flange of the housing.

4. The apparatus of claim 3, wherein the air filter is at least partially retained within the cavity by abutting contact of the cover.

5. The apparatus of any one of claims 1-4, further comprising a first O-ring and a second O-ring that together seal the cover to the housing, wherein the first O-ring is arranged at a substantially 90 degree angle to the second O-ring, wherein the housing includes a first groove that receives the first O-ring, and the cover includes a second groove that receives the second O-ring.

6. The apparatus of claim 5, wherein the cover includes a flange sealed with the first O-ring and a body sealed with the second O-ring.

7. The apparatus of any one of claims 1-6, wherein the housing is spaced apart from an outer circumference of the air filter to allow air from the inlet to circulate around at least a portion of the outer circumference before passing through the air filter to the outlet.

8. A method of maintaining an air filter for supplying air to a crankcase of an internal combustion engine, the method comprising: providing a housing forming a cavity and having an inlet and an outlet therein; positioning the air filter within the cavity and at least partially retained by the housing; providing a cover sealed to the housing at at least two locations; as well as The cover is removed from the housing to access the air filter within the cavity.

9. The method of claim 8, wherein positioning the air filter within the cavity comprises positioning the air filter such that an outer circumference of the air filter is oriented at an angle substantially tangential to the inlet.

10. The method according to any one of claims 8 to 9, further comprising: removing the air filter from the cavity; inserting a second air filter into the cavity; The cover is sealed to the housing at the at least two locations Wherein positioning the air filter within the cavity further comprises abutting the air filter with the cover to at least partially retain the air filter.

11. The method of any one of claims 8-10, wherein positioning the air filter within the cavity and at least partially retained by the housing comprises aligning the air filter with a groove and a flange of the housing and inserting the air filter into the groove of the housing.

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