Patent Description:
Some embodiments of the technology disclosed herein relates to a vent having a vent housing defining a mounting structure, a first end, a second end, a first opening between the first end and the second end, a first airflow pathway extending from the first opening, a second opening, a second airflow pathway extending from the second opening, and a draining pathway extending from the first airflow pathway through the first end of the vent housing. The first airflow pathway has a first segment extending in a first axial direction and a second segment extending in an opposite axial direction from the first axial direction. An inlet relief valve is coupled to the housing between the first airflow pathway and the second airflow pathway. The inlet relief valve is biased in a closed position and is configured to open upon a pressure differential of the second airflow pathway relative to the first airflow pathway exceeding a first threshold pressure. An outlet relief valve is coupled to the housing between the first airflow pathway and the second airflow pathway. The outlet relief valve is biased in a closed position. The outlet relief valve is arranged in parallel with the inlet relief valve. The outlet relief valve is configured to open upon a pressure differential of the first airflow pathway relative to the second airflow pathway exceeding a second threshold pressure. A filter assembly is disposed in the vent housing. The filter assembly extends across the second airflow pathway.

In some such embodiments, the mounting structure defines a bayonet coupler that is configured to couple to a mating bayonet connector. Additionally or alternatively, the vent housing defines a first end and a second end, where the filter assembly is towards the second end. Additionally or alternatively, the inlet relief valve and the outlet relief valve are integrated in a single component. Additionally or alternatively, the inlet relief valve is an elastomeric cross-slit valve. Additionally or alternatively, the inlet relief valve comprises an elastomeric valve having a displaceable sealing lip sealably surrounding an inlet opening. Additionally or alternatively, the outlet relief valve has a plug sealably disposed across an outlet opening and a spring compressibly disposed between the plug and the vent housing, where the plug is translatable away from the outlet opening. Additionally or alternatively, the outlet opening surrounds the inlet opening. Additionally or alternatively, the inlet relief valve is directly coupled to the outlet relief valve.

Additionally or alternatively, the vent has a filter casing surrounding the filter assembly, the filter casing having an outer cap and an inner cap, where the outer cap and the inner cap are secured around the filter assembly. Additionally or alternatively, the outer cap defines the mounting structure. Additionally or alternatively, the outer cap and the inner cap form a snap fit connection around the filter assembly. Additionally or alternatively, the second opening is defined between the outer cap and the inner cap. Additionally or alternatively, the inlet relief valve and the outlet relief valve are disposed between the inner cap and the outer cap.

Additionally or alternatively, the inner cap defines the first opening and the first airflow pathway. Additionally or alternatively, the first airflow pathway defines a tortuous path from the first opening towards the inlet relief valve. Additionally or alternatively, the filter assembly has first filter media surrounding a central opening and the inlet relief valve and the outlet relief valve are disposed in the central opening. Additionally or alternatively, the first filter media has pleated filter media having first pleat folds abutting the central opening and second pleat folds radially outward from the first pleat folds. Additionally or alternatively, the vent has a second filter media surrounding the first filter media, wherein the first filter media and the second filter media are arranged in a series in the second airflow pathway. Additionally or alternatively, the vent is configured to be sealably received by a hydraulic tank about a fill port.

Some embodiments of the current technology relate to a vent system. The vent system has a vent consistent with any of those described above. The system has a tank interface having a vent mount configured to be fixed to a liquid tank. The vent mount defines a mount opening, and the vent mount has a mating structure configured to sealably mate with the mounting structure of the vent around the housing.

In some such embodiments, the system has a strainer disposed in the mount opening, where the strainer is configured to extend from the vent mount into the liquid tank in the axial direction, and the strainer is configured to receive the first end of the vent. Additionally or alternatively, the mating structure has a bayonet connector. Additionally or alternatively, the mating structure has a vent sealing surface. Additionally or alternatively, the vent mount further has a plurality of radially extending deflectors that are configured to partially obstruct the second airflow pathway. Additionally or alternatively, the radially extending deflectors extend radially outward from an outer radial surface of the vent mount.

The above summary is not intended to describe each embodiment or every implementation. Rather, a more complete understanding of illustrative embodiments will become apparent and appreciated by reference to the following Detailed Description of Exemplary Embodiments and claims in view of the accompanying figures of the drawing.

The present technology may be more completely understood and appreciated in consideration of the following detailed description of various embodiments in connection with the accompanying drawings.

The figures are rendered primarily for clarity and, as a result, are not necessarily drawn to scale. Moreover, various structure/components, including but not limited to fasteners, electrical components (wiring, cables, etc.), and the like, may be shown diagrammatically or removed from some or all of the views to better illustrate aspects of the depicted embodiments, or where inclusion of such structure/components is not necessary to an understanding of the various exemplary embodiments described herein. The lack of illustration/description of such structure/components in a particular figure is, however, not to be interpreted as limiting the scope of the various embodiments in any way.

The technology disclosed herein is generally related to a liquid tank vent. The liquid tank can be a hydraulic fluid tank, in various implementations. The liquid tank vent combines a variety of features that improves its functionality compared to existing liquid tank vents. The liquid tank vent may incorporate filter media to advantageously prevent the ingress of water into the liquid tank and remove moisture from the liquid tank. Furthermore, the liquid tank vent may have filter media to filter particulates from the air entering the liquid tank. The liquid tank vent may incorporate features that provide splash protection outside the liquid tank, inside the liquid tank, or both outside the liquid tank and inside the liquid tank. The liquid tank vent may define a draining pathway that advantageously returns stored liquid that splashes onto the tank vent back to the tank. The liquid tank vent may advantageously prevent the release of stored liquid to the environment outside of the tank vent. These and other advantages may result from designs consistent with the present disclosure.

<FIG> depicts a first perspective view of an example vent <NUM> consistent with some embodiments. <FIG> depicts a second perspective view of the example vent <NUM> and <FIG> depicts an example cross-sectional view of the vent of <FIG>. The vent <NUM> is generally configured to sealably couple to a liquid tank of a system to allow two-way air venting of the liquid tank and prevent the ingress of contaminants such as particles and liquids to the tank. The vent <NUM> can be configured to sealably couple to a liquid tank where the volume of liquid within the liquid tank fluctuates over the course of normal operations of the system. In some implementations the vent <NUM> is configured to accommodate airflow into the liquid tank upon a threshold vacuum between the interior of the liquid tank and the external environment. In some implementations the vent <NUM> is configured to accommodate airflow out of the liquid tank upon a threshold pressure between the interior of the liquid tank and the external environment. The vent <NUM> can be configured to filter the air passing between the tank and the external environment. In some embodiments, the vent <NUM> is configured to remove water vapor from the liquid tank. In various embodiments the vent <NUM> is configured to prevent liquid from the liquid tank from leaking into the external environment.

The vent <NUM> generally has a vent housing <NUM>, an inlet relief valve <NUM>, an outlet relief valve <NUM>, and a filter assembly <NUM>. The vent housing <NUM> is generally configured to house various components of the vent and direct airflow through the vent housing <NUM>. The housing can be constructed of a variety of materials and combinations of materials such as polymers or metals, as will be appreciated by those having skill in the art.

The vent housing <NUM> defines a first end, a second axial end <NUM>, a first opening <NUM>, a second opening <NUM>, and a mounting structure <NUM>. The vent housing <NUM> has a mounting structure <NUM> that is configured to be installed on a liquid tank. The mounting structure <NUM> of the vent is generally configured to sealably couple to a liquid tank about an opening defined in the liquid tank. The vent can be configured to be sealably received by a hydraulic tank about a fill port. The mounting structure <NUM> is configured to create a seal between the first opening <NUM> and the second opening <NUM> in the environment outside of the vent. Upon installation on a liquid tank, a first axial end <NUM> of the vent housing <NUM> can generally be configured to be positioned inside of the liquid tank. In various embodiments the second axial end <NUM> of the vent housing <NUM> is configured to be positioned outside the liquid tank. In the current example, the mounting structure <NUM> includes a seal <NUM> disposed on a sealing flange <NUM> of the housing <NUM> and a bayonet coupler <NUM> that is configured to couple to a mating bayonet connector, which will be described in more detail below. The seal <NUM> is disposed between the first opening <NUM> and the second opening <NUM> in the axial direction, the lateral direction, or both in the axial direction and lateral direction, where "lateral" is used herein as meaning perpendicular to the axial direction.

The first opening <NUM> is positioned between the first axial end <NUM> and the second axial end <NUM>. The vent housing <NUM> defines a first airflow pathway <NUM> extending from the first opening <NUM>. The vent housing <NUM> defines a second airflow pathway <NUM> extending from the second opening <NUM>. The vent housing <NUM> of the vent is generally configured to accommodate airflow between the interior of a tank (to which the vent is coupled) and the external environment through the first opening <NUM>, second opening <NUM>, first airflow pathway <NUM> and the second airflow pathway <NUM>. The first airflow pathway <NUM> is configured for direct communication with the interior of a tank and a second airflow pathway <NUM> is configured for direct communication with the external environment.

The vent has two oppositely-functioning relief valves that are each coupled to the vent housing <NUM>. The relief valves are arranged in parallel between the first airflow pathway <NUM> and the second airflow pathway <NUM>. Each of the relief valves are biased to a closed position where the first airflow pathway <NUM> and the second airflow pathway <NUM> are separated from each other within the vent housing <NUM>. The relief valves include an inlet relief valve <NUM> and an outlet relief valve <NUM>. The inlet relief valve <NUM> is coupled to the vent housing <NUM> between the first airflow pathway <NUM> and the second airflow pathway <NUM>. The inlet relief valve <NUM> is generally biased in a closed position but is configured to open upon a pressure differential of the second airflow pathway <NUM> relative to the first airflow pathway <NUM> that exceeds a first threshold pressure. In other words, when the vent <NUM> is installed in a tank, the inlet relief valve <NUM> is configured to open upon a threshold partial vacuum in the tank relative to the external environment.

The outlet relief valve <NUM> is also coupled to the vent housing <NUM> between the first airflow pathway <NUM> and the second airflow pathway <NUM>. The outlet relief valve <NUM> is biased in a closed position and is configured to open upon a pressure differential of the first airflow pathway <NUM> relative to the second airflow pathway <NUM> exceeds a second threshold pressure. In other words, when the vent <NUM> is installed in a liquid tank, the outlet relief valve <NUM> is configured to open when there is a threshold partial vacuum in the external environment relative to inside of the tank.

The outlet relief valve <NUM> is arranged in parallel with the inlet relief valve <NUM> between the first airflow pathway <NUM> and the second airflow pathway <NUM>. The inlet relief valve <NUM> and the outlet relief valve <NUM> can have a variety of configurations consistent with the technology disclosed herein. In the current example, the vent housing <NUM> defines a valve opening <NUM> between the first airflow pathway <NUM> and the second airflow pathway <NUM>. The inlet relief valve <NUM> and the outlet relief valve <NUM> cumulatively extend across the valve opening <NUM> in a parallel arrangement. More particularly, the outlet relief valve <NUM> extends across an outlet opening <NUM> (that, in the current embodiment is the same opening as the valve opening <NUM>) and forms a seal with the vent housing <NUM> about the outlet opening <NUM>. The inlet relief valve <NUM> extends across an inlet opening <NUM> and forms a seal about the inlet opening <NUM>. In the current example, the outlet opening <NUM> and the valve opening <NUM> are co-extensive. The outlet relief valve <NUM> defines the inlet opening <NUM> such that the inlet opening <NUM> is within the valve opening <NUM>. As such, the outlet opening <NUM> (and the valve opening <NUM>) surrounds the inlet opening <NUM>. The inlet relief valve <NUM> extends across the inlet opening <NUM> and forms a seal with the outlet relief valve <NUM> about the inlet opening <NUM>. As such, in the current example, the inlet relief valve <NUM> is directly coupled to the outlet relief valve <NUM>.

In some other embodiments, the inlet relief valve <NUM> and the outlet relief valve <NUM> are each directly coupled to the housing. Such a configuration may be employed where the vent housing <NUM> defines a valve opening <NUM> that includes an outlet opening <NUM> and an inlet opening <NUM> that are discrete, separate openings. In some such embodiments the inlet relief valve <NUM> and the outlet relief valve <NUM> extend across the inlet opening <NUM> and the outlet opening <NUM>, respectively, and the inlet relief valve <NUM> and the outlet relief valve <NUM> do not make direct contact.

In the current example, the inlet relief valve <NUM> is an elastomeric valve. In particular, the inlet valve has a displaceable sealing lip <NUM> that forms a seal around the inlet opening <NUM>. The sealing lip <NUM> is configured to obstruct the inlet opening <NUM> under the first threshold pressure differential between the second airflow pathway <NUM> and the first airflow pathway <NUM>. The sealing lip <NUM> is configured to clear the inlet opening <NUM> over the first threshold pressure differential between the second airflow pathway <NUM> and the first airflow pathway <NUM>. In particular, the sealing lip <NUM> is in direct contact with the first airflow pathway <NUM> and the second airflow pathway <NUM> such that, upon the first threshold pressure differential, the pressure in the second airflow pathway <NUM> pushes against the sealing lip <NUM> to flex at least a portion of the sealing lip <NUM> away from the inlet opening <NUM>. In the current example, the sealing lip <NUM> is defined by an umbrella-shaped portion that extends across the inlet opening <NUM>. Such a configuration can advantageously obstruct liquids from passing through the inlet opening <NUM> towards the filter assembly <NUM>, such as when a liquid contained in a liquid tank would splash upwards towards the inlet valve.

While in the current example, the displaceable sealing lip <NUM> sealably surrounds the inlet opening <NUM>, other configurations are also contemplated. For example, the inlet valve can have a duckbill or slit configuration, for example, where mating displaceable sealing lips are in sealing contact across the inlet opening <NUM> and are configured to separate under the first threshold pressure differential between the second airflow pathway <NUM> and the first airflow pathway <NUM>. In some other embodiments the inlet-relief valve is translatable plug sealably disposed across the inlet opening <NUM>. In such an example, a portion of the inlet relief valve <NUM> can be configured to translate away from the inlet opening <NUM> upon the first threshold pressure differential.

In the current example, the outlet relief valve <NUM> is configured as a plug <NUM> sealably disposed across the outlet opening <NUM>. The vent housing <NUM> defines a valve seat <NUM> surrounding the outlet opening <NUM>, and the outlet relief valve <NUM> is configured to be biased in a position against the valve seat <NUM>. A spring <NUM> is compressibly disposed between the plug <NUM> and the vent housing <NUM>. The spring <NUM> has a first end <NUM> coupled to the plug <NUM> and a second end <NUM> coupled to the vent housing <NUM>. The spring <NUM> exerts a force that biases the plug <NUM> in sealing contact with the valve seat <NUM> about the outlet opening <NUM>. The plug <NUM> is translatable away from the outlet opening <NUM>. The plug <NUM> is translatable away from the outlet opening <NUM> in a direction opposing the biasing force of the spring <NUM>. In particular, the plug <NUM> is in direct contact with the first airflow pathway <NUM> and the second airflow pathway <NUM> such that, upon the second threshold pressure differential, the pressure in the first airflow pathway <NUM> pushes against the plug <NUM> and the spring <NUM> to translate at least a portion of the plug <NUM> away from the outlet opening <NUM>.

In various embodiments, the outlet relief valve <NUM> is advantageously configured to prevent lateral displacement of portions of the spring <NUM>. Lateral displacement of portions of the spring may prevent predictable re-seating of the outlet relief valve <NUM> on the valve seat <NUM> if spring expansion forces are shifted away from the axial direction. Referring to <FIG>, which is an exploded view of the example vent, in the current example, the outlet relief valve <NUM> has a first spring guide <NUM> that is configured to receive the first end <NUM> of the spring <NUM>. In particular, the first spring guide <NUM> surrounds the spring <NUM> and is configured to maintain the spring <NUM> in axial alignment. The first spring guide <NUM> extends outwardly from the valve sealing surface <NUM> in the axial direction towards the second end <NUM> of the spring <NUM>. The first spring guide <NUM> has an inner lateral dimension (such as an inner diameter) that is slightly greater than the outer lateral dimension of the spring <NUM>. In the current example, the first spring guide <NUM> is continuous around the first end <NUM> of the spring <NUM>, but in some other embodiments the first spring guide <NUM> can a plurality of individual axial extensions that cumulatively surround the first end <NUM> of the spring <NUM>.

Furthermore, in the current embodiment, the vent housing <NUM> has a second spring guide <NUM> that is configured to receive the second end <NUM> of the spring <NUM>. In particular, the second spring guide <NUM> surrounds the spring <NUM> and is configured to maintain the spring <NUM> in axial alignment. The second spring guide <NUM> extends outwardly from an inner lateral surface of the second axial end <NUM> of the vent housing <NUM> in the axial direction towards the first end <NUM> of the spring <NUM>. The second spring guide <NUM> has an inner lateral dimension (such as an inner diameter) that is slightly greater than the outer lateral dimension of the spring <NUM>. In the current example, the second spring guide <NUM> is continuous around the second end <NUM> of the spring <NUM>, but in some other embodiments the second spring guide <NUM> can a plurality of individual axial extensions that cumulatively surround the second end <NUM> of the spring <NUM>. While in the current example, the second spring guide <NUM> is integral with the second axial end <NUM> of the vent housing <NUM>, in some other embodiments, the second spring guide <NUM> can be a separate component that is coupled to the second axial end <NUM> of the vent housing <NUM>.

In some embodiments the combined axial length of the first spring guide <NUM> and the second spring guide <NUM> is less than the axial length of the spring under maximum compression under normal operating conditions. In some embodiments the combined axial length of the first spring guide <NUM> and the second spring guide <NUM> is more than <NUM>%, or more than <NUM>% of the axial length of the spring <NUM> when the spring <NUM> is in a fully expanded state where the plug <NUM> is properly seated on the valve seat <NUM>.

In various embodiments, the vent <NUM> is advantageously configured to prevent lateral displacement of the plug <NUM> of the outlet relief valve <NUM>. Lateral displacement of the plug <NUM> may prevent its proper seating on the valve seat <NUM> to seal the outlet opening <NUM>. As such, in the current example, the vent housing <NUM> has a valve guide <NUM> that defines a linear translation pathway for the plug <NUM>. In particular, the valve guide <NUM> surrounds the plug <NUM> and, in particular, the valve sealing surface <NUM> of the plug, and is configured to maintain the plug along an axial linear translation pathway. The valve guide <NUM> extends outwardly from the valve seat <NUM> in the axial direction towards the second end <NUM> of the spring <NUM>. The valve guide <NUM> has an inner lateral dimension (such as an inner diameter) that is slightly greater than the outer lateral dimension of the plug <NUM>. In the current example, the valve guide <NUM> is a plurality of individual axial extensions <NUM> that cumulatively surround the plug <NUM>, but in some other embodiments the valve guide <NUM> can be continuous around the plug <NUM>. The valve guide <NUM> can have an axial length that is greater than or equal to the maximum expected translation of the plug <NUM> away from the valve seat <NUM>. While in the current example, the valve guide <NUM> can be integral with the vent housing <NUM> and the valve seat <NUM>, in some other embodiments the valve guide <NUM> can be a separate component that is coupled to the vent housing <NUM>, such as coupled to the valve seat <NUM>.

<FIG> shows an alternate example of a vent <NUM> consistent with the technology disclosed herein. The vent <NUM> is generally consistent with the descriptions of <FIG> except where contradictory to the current figure and description. In this example, the functions and structures of the valve guide <NUM> and the second spring guide <NUM> discussed above and shown in <FIG> are integrated in a single component that is referred to as a valve cage <NUM>. The valve cage <NUM> has a first end <NUM> defining a coupling structure <NUM> that is configured to couple to the vent housing <NUM> around the valve seat <NUM>. In particular, the coupling structure <NUM> is inner circumferential threads <NUM> that mate with outer circumferential threads <NUM> defined around the valve seat <NUM>. Other types of coupling structures can alternatively be used such as an interference fit, bayonet connection, and so on. The valve cage <NUM> has a second end <NUM> that is positioned between the lateral sidewall <NUM> on the second end <NUM> of the housing <NUM> and the second end <NUM> of the spring <NUM>. The valve cage <NUM> has a plurality of axial extensions <NUM> that are positioned circumferentially around the spring <NUM>. Each of the axial extensions <NUM> extend from the first end <NUM> to the second end <NUM> of the valve cage <NUM>. The valve cage <NUM> defines a linear translation pathway for the plug <NUM> in the axial direction. The valve cage <NUM> helps to retain the spring <NUM> in axial alignment.

<FIG> depicts an example vent <NUM> consistent with the examples depicted in <FIG> with the plug <NUM> away from the outlet opening <NUM>. The plug <NUM> is translatably disposed in the second airflow pathway <NUM> but defines a facing surface <NUM> that is in fluid communication with the first airflow pathway <NUM>. As such, the pressure in the first airflow pathway <NUM> is exerted on the facing surface <NUM> against the combined force of the spring <NUM> and the pressure in the second airflow pathway <NUM>.

It is noted that, in the current example, the facing surface <NUM> of the plug <NUM> of the outlet relief valve <NUM> is defined by at least a portion of the inlet relief valve <NUM>. More particularly, an umbrella-shaped portion of the inlet relief valve <NUM> that extends over the inlet opening <NUM> forms at least a portion of the facing surface <NUM> of the plug <NUM>. However, in some other embodiments a portion of the inlet relief valve <NUM> does not form a portion of the facing surface <NUM> of the outlet relief valve <NUM>.

In the current example the plug <NUM> of the outlet relief valve <NUM> has a valve sealing surface <NUM> that is configured to form a seal with the vent housing <NUM> about the outlet opening <NUM>. The valve sealing surface <NUM> can be formed by a sealing ring retained about the plug <NUM> that is configured to directly contact the vent housing <NUM> about the outlet opening <NUM>. It will be appreciated that the outlet relief valve <NUM> can have a variety of alternate configurations. In some embodiments a sealing ring can be coupled to the vent housing <NUM> about the outlet opening <NUM> that the plug sealing surface is configured to come into contact with about the outlet opening <NUM>. In some embodiments the plug <NUM> is constructed of an elastomeric material so a separate seal component need not be used between the plug <NUM> and the vent housing <NUM> about the outlet opening <NUM>. In some embodiments the outlet relief valve <NUM> can be an elastomeric valve such as an umbrella-shaped valve, a duckbill valve, or another type of elastomeric valve. In some embodiments the outlet relief valve <NUM> is pivotable rather than linearly translatable away from the outlet opening <NUM>.

<FIG> is a cross-sectional view of an alternate valve assembly <NUM> consistent with various embodiments. The valve assembly <NUM> can be used in place of the inlet relief valve and the outlet relief valve as previously described. The valve assembly <NUM> has an outlet relief valve that is a plug <NUM> coupled to a spring <NUM>, consistent with descriptions elsewhere herein, and the valve assembly <NUM> functions consistently with examples discussed above. In this example, the plug <NUM> is constructed of an elastomeric material that forms a seal with the valve mating surface. Also, in the current example, the plug <NUM> also forms the inlet relief valve <NUM>. In particular, the plug <NUM> is a cross-slit one-way relief valve that is the inlet relief valve <NUM>. Opposing sealing lips <NUM> are biased in a closed position. Upon the first pressure differential, the sealing lips <NUM> separate to allow airflow from the second airflow pathway to the first airflow pathway.

Returning to a discussion of <FIG>, the filter assembly <NUM> is generally configured to filter contaminants from the air passing between the first airflow pathway <NUM> and the second airflow pathway <NUM>. The filter assembly <NUM> is disposed in the vent housing <NUM>. In various embodiments, the filter assembly <NUM> extends across the second airflow pathway <NUM>. The second airflow pathway <NUM> extends through the filter assembly <NUM>. The filter assembly <NUM> can have a variety of different configurations. However, in the current example, the filter assembly <NUM> has at least first filter media <NUM> disposed across the second airflow pathway <NUM> such that the first filter media <NUM> defines a portion of the second airflow pathway <NUM>. The first filter media <NUM> can also have a variety of different configurations, but in the current example, the first filter media <NUM> has a tubular structure having an inner circumference <NUM>, an outer circumference <NUM>, a first axial end <NUM> and a second axial end <NUM>. The inner circumference <NUM> defines an outer boundary of a central opening <NUM> of the filter assembly <NUM> in the second airflow pathway <NUM> of the vent <NUM>.

The first filter media <NUM> is pleated in the current example. The first filter media <NUM> defines pleats extending from the inner circumference <NUM> to the outer circumference <NUM> such that pleat folds define the inner circumference <NUM> and the outer circumference <NUM>. First pleat folds abut the central opening <NUM> and second pleat folds are radially outward from the first pleat folds. Pleating the first filter media <NUM> increases the surface area of the first filter media <NUM>, which can increase airflow through the first filter media <NUM>. Maximizing airflow can be desirable in implementations where the volume of fluid in a tank fluctuates rapidly. For example, in tanks used in hydraulic systems, the level of hydraulic oil in the tank can change rapidly during various operations, necessitating the rapid exchange of air between the tank and the outside environment. In some alternate configurations, the first filter media <NUM> can be wrapped around the central opening to define a spiral configuration. In yet another embodiment the first filter media <NUM> does not define a central opening.

It is noted that, in the current example where the filter assembly <NUM> defines the central opening, the inlet relief valve <NUM> and the outlet relief valve <NUM> are disposed in the central opening <NUM>. Such a configuration can advantageously allow for a relatively compact vent compared to a design where the relief valve(s) are positioned outside the central opening or where no central opening is defined by the filter assembly <NUM> and the relief valve(s) are positioned adjacent to the filter assembly <NUM>.

The first filter media <NUM> can be constructed of a variety of different types of materials and combinations of materials. The first filter media <NUM> can generally be configured for particle filtration. In some embodiments the first filter media <NUM> incorporates filter media fibers. The filter media fibers can include cellulose fibers, for example. In some embodiments the first filter media <NUM> incorporates polymeric fibers. The first filter media <NUM> can incorporate binders and/or resins among the filter media fibers, and in some other embodiments the first filter media <NUM> omits resinous binders. In some embodiments the first filter media <NUM> includes binder fibers and omits other binder materials such as binder resins. The first filter media <NUM> can have multiple layers include one or more layers of filter media and one or more support layers such as a scrim layer. The scrim layer can be constructed of various types of materials and combinations of materials known in the art. In one embodiment the scrim layer is polyester. The scrim layer can also be other materials and combinations of materials such as, for example, PE, PET, and polypropylene.

Various vents consistent with the current technology incorporates a second filter media <NUM>. The second filter media <NUM> generally extends across second airflow pathway <NUM>. The second filter media <NUM> can have alternate and/or complementary functionality to the first filter media <NUM>. The first filter media <NUM> and the second filter media <NUM> are arranged in a series in the second airflow pathway <NUM>. In the current example, the second filter media <NUM> surrounds the first filter media <NUM>. In some alternate embodiments the first filter media <NUM> surrounds the second filter media <NUM>. In some such embodiments the second filter media <NUM> can define the central opening of the filter assembly <NUM>. While in the current example the second filter media <NUM> defines a central opening, in some other embodiments the second filter media <NUM> does not define a central opening.

In a variety of implementations, moisture can be released from the liquid in the tank into the air within the airspace of the tank, where "moisture" is defined as water or water vapor. The moisture can contribute to oxidation of system components, and if the moisture condenses into water droplets and falls into the liquid tank, such water droplets may interfere with the system operation. As such, in various embodiments, the second filter media <NUM> can be configured to aid in the removal of moisture from the tank. In some embodiments the second filter media <NUM> can also be configured to filter out particulates between the first airflow pathway <NUM> and the second airflow pathway <NUM>. In a variety of embodiments the second filter media <NUM> is a hygroscopic filter media, where "hygroscopic" is defined herein as the ability to accelerate the condensation of water vapor.

In some embodiments the second filter media <NUM> is a regenerative hygroscopic filter media. The second filter media <NUM> can be configured to filter particulates and water when gas passes from the second airflow pathway <NUM> to the first airflow pathway <NUM>. The second filter media <NUM> can be configured to release water via the second airflow pathway <NUM> when air passes from the first airflow pathway <NUM> through the second filter media <NUM>. The second filter media <NUM> can be consistent with filter medias disclosed, for example, in <CIT>, which is incorporated herein by reference. In at least one embodiment the second filter media <NUM> is a T. Breather Filter manufactured by Donaldson Corporation headquartered in Bloomington, Minn. Those having skill in the art will appreciate that other filter medias may also be appropriate for specific implementations of the technology disclosed herein.

The filter assembly <NUM> is generally configured to sealably couple to the vent housing <NUM> such that the second airflow pathway <NUM> extends through the filter media (in particular to this example, the first filter media <NUM> and the second filter media <NUM>). In this particular example, the filter assembly has a first endcap <NUM> and a second endcap <NUM>. The first endcap <NUM> is sealed to a first axial end <NUM> of the first filter media <NUM> and the second endcap <NUM> is sealed to a second axial end <NUM> of the first filter media <NUM>. Each endcap <NUM>, <NUM> has a sealing surface that is configured to form a seal with the vent housing <NUM>. The sealing surface can be defined by a sealing ring that is compressed between each of the endcaps <NUM>, <NUM> and the vent housing <NUM> about the central opening.

The vent housing <NUM> can have a variety of different configurations without departing from the scope of the technology disclosed herein. The vent housing <NUM> defines a filter casing that encloses the filter assembly <NUM>. In the current example, the filter casing also encloses the inlet relief valve <NUM> and the outlet relief valve <NUM>. Enclosing the filter assembly <NUM> can be desirable in configurations where the filter assembly <NUM> is constructed of one or more materials that may be negatively impacted or may cause a negative impact upon making contact with a user, components, and debris from the outside environment. The filter casing has an outer cap <NUM> and an inner cap <NUM> that are secured together.

In this example the outer cap <NUM> and inner cap <NUM> are secured with a series of interlocking snap fit structures <NUM>, <NUM> (best visible in <FIG>. In particular, the outer cap <NUM> defines a series of openings <NUM>, and the inner cap <NUM> defines a series of protrusions <NUM> that are configured to engage the series of openings <NUM> through an interference fit. In various embodiments the outer cap <NUM> and the inner cap <NUM> are secured in a non-releasable manner, meaning that the connection between the outer cap <NUM> and the inner cap <NUM> cannot be mechanically reversed without causing damage to one or both of the outer cap <NUM> and the inner cap <NUM>. The outer cap <NUM> and the inner cap <NUM> can be coupled through alternate approaches such as a press fit, screw fit, frictional fit, weld, adhesive, and the like.

The outer cap <NUM> is generally configured to shield the filter assembly <NUM> from the outside environment. The outer cap <NUM> has a lateral sidewall <NUM> that extends laterally across the second axial end <NUM> of the filter assembly <NUM> and a circumferential sidewall <NUM> that extends circumferentially around the filter assembly <NUM> and circumferentially around the second airflow pathway <NUM>. The circumferential sidewall <NUM> extends from the lateral sidewall <NUM> towards the first axial end <NUM> of the vent housing <NUM> in the axial direction. The outer cap <NUM> is also generally configured to receive the filter assembly <NUM>. In particular, the outer cap <NUM> sealably receives the sealing surface of the second endcap <NUM> of the filter assembly <NUM>. In the current example, the outer cap <NUM> has an outer axial baffle <NUM> that extends axially towards the first axial end <NUM> of the vent housing from the lateral sidewall <NUM>. The outer axial baffle <NUM> can be configured to obstruct liquid in the outside environment from splashing onto the filter assembly <NUM>. In some embodiments, the outer axial baffle <NUM> can also be configured to abut the second axial end <NUM> of the filter assembly <NUM> to maintain the position of the filter assembly <NUM>.

In the current example, the outer cap <NUM> is coupled to the second end of the spring <NUM> of the outlet relief valve <NUM>. The outer cap <NUM> can further be configured to couple to a liquid tank. In particular, the outer cap <NUM> can define a bayonet coupler <NUM> (visible in <FIG>) that is configured to receive a mating bayonet connector that is fixed to the liquid tank. In the current example, the bayonet coupler <NUM> is a series of tabs that extend radially into the second airflow pathway <NUM>. In some other embodiments, the bayonet coupler <NUM> can be a series of tabs that extend radially outward from the outer cap <NUM>.

The inner cap <NUM> is generally configured to receive the filter assembly <NUM>. The inner cap <NUM> has an annular sidewall <NUM> that extends laterally across the first axial end <NUM> of the filter assembly <NUM>. The annular sidewall <NUM> extends radially outward from the central opening <NUM> of the filter assembly <NUM> beyond the second filter media <NUM>. The inner cap <NUM> sealably receives the sealing surface of the first endcap <NUM> of the filter assembly <NUM>. The annular sidewall <NUM> forms a seal with the filter assembly <NUM> about the central opening <NUM>. In the current example, an inner axial flange <NUM> and an outer axial flange <NUM> abuts the inner perimeter and the outer perimeter of the filter assembly <NUM>, respectively. The inner axial flange <NUM> and the outer axial flange <NUM> can be configured to maintain the position of the filter assembly <NUM> relative to the inner cap <NUM>. The inner axial flange <NUM> extends circumferentially around the central opening <NUM> of the filter assembly <NUM>. The outer axial flange <NUM> can extend circumferentially around the filter assembly <NUM>.

In some embodiments, the outer axial flange <NUM> can also be configured to obstruct liquid in the outside environment from splashing onto the filter assembly <NUM>. The outer axial flange <NUM> is positioned radially inwardly relative to the snap fit structures <NUM>, <NUM>. The outer axial flange <NUM> has a circumferential length that extends around the filter assembly <NUM>. The outer axial flange <NUM> is positioned radially inward from the snap fit structures <NUM>, <NUM>. The outer axial flange <NUM> can have first circumferential sections 153a that are each in radial alignment with a corresponding interlocking snap fit structures <NUM>, <NUM> and second circumferential sections 153b that are outside of radial alignment with each of the snap fit structures <NUM>, <NUM>. The first circumferential sections 153a have a greater axial length than the second circumferential sections 153b of the outer axial flange <NUM> (visible in <FIG>). In various embodiments, including those currently depicted, the first circumferential sections 153a of the outer axial flange <NUM> each have a circumferential length Lc (such as a radial arc) that is greater than the circumferential length of the corresponding snap fit structure <NUM>,<NUM>. Such a configuration may advantageously prevent liquid from entering the vent housing <NUM> through the openings <NUM> to make contact with the filter assembly <NUM>.

In examples, the first circumferential segments 153a of the outer axial flange <NUM> can have one or more projections to further obstruct liquid, such as splashing liquid, from entering the vent housing <NUM>. Such an example is depicted in <FIG>, which is a perspective view of an alternate design of an inner cap <NUM> consistent with the technology disclosed herein. The inner cap <NUM> is generally consistent with inner caps discussed elsewhere herein unless contradictory to the current description. Similar to the discussion above, the inner cap <NUM> has an outer axial flange <NUM> that extends circumferentially around the filter cavity. The outer axial flange <NUM> is positioned radially inward from the snap fit structure <NUM>. The outer axial flange <NUM> has first circumferential segments 553a that are radially aligned with a corresponding snap fit structure <NUM> and second circumferential segments 553b that are not radially aligned with any snap fit structures <NUM>. In this example, each of the first circumferential segments 553a has a pair of projections <NUM> positioned laterally outward from the corresponding snap fit structure <NUM>. The projections <NUM> taper outward from the first circumferential segment 553a. Such a configuration may advantageously obstruct the entry of splashing liquid to the filter housing. The projections can have alternate configurations, as well.

Returning back to the examples depicted in <FIG>, the inner cap <NUM> defines the valve opening <NUM> and the valve seat <NUM> surrounding the valve opening <NUM>. The valve seat <NUM> is configured to receive the valve sealing surface <NUM> of the outlet relief valve <NUM>. The inner cap <NUM> can further be configured to couple to a liquid tank. In particular, the inner cap <NUM> has a sealing flange <NUM> that has a seal <NUM> coupled thereto. The sealing flange <NUM> is a component of the mounting structure <NUM>. The sealing flange <NUM> extends axially towards the first axial end <NUM> of the vent housing <NUM> about the first airflow pathway <NUM>. The sealing flange <NUM> is configured to be sealingly coupled to a liquid tank about a tank opening. In the current example the seal <NUM> is a radial seal, but in other examples the seal can be an axial seal. Furthermore, in the current example the seal <NUM> is positioned towards a proximal end of the sealing flange <NUM> but in some other embodiments the seal <NUM> can be positioned towards the opposite, distal end of the sealing flange <NUM>. "Proximal" is used herein to refer to a component configured to be situated further within the interior volume of a liquid tank, and "distal" is used herein to refer to a component configured to be situated further from the interior volume of a liquid tank.

The inner cap <NUM> defines the first axial end <NUM> of the vent <NUM>. In particular, the inner cap <NUM> extends from the valve seat <NUM> towards the first axial end <NUM> of the vent housing <NUM>. The first axial end <NUM> of the vent is configured to be received by a volume of the liquid tank to which the vent is mounted. The first opening <NUM> (particularly visible in <FIG>) of the vent housing <NUM> is configured to be in direct fluid communication with the interior of the liquid tank. In the current example, the first opening <NUM> is a series of discrete openings defined by the vent housing <NUM> around the central opening <NUM>. The first opening <NUM> is a series of discrete openings defined by the vent housing <NUM> around the central axis x. In the current example, the first opening <NUM> is perpendicular to the axial direction of vent <NUM>. The first opening <NUM> is positioned between the first axial end <NUM> and the second axial end <NUM>. In various embodiments, the first opening <NUM> is not defined on the first axial end <NUM> of the vent <NUM>. The first opening <NUM> may advantageously limit splashing of liquid from the liquid tank into the first opening <NUM>. In some other examples the first opening <NUM> is parallel to the axial direction of the vent <NUM> and is configured to face an adjacent surface of a liquid tank (rather than the tank volume) upon installation of the vent <NUM> onto the liquid tank.

The first airflow pathway <NUM> extends from the first opening <NUM> to the inlet relief valve <NUM> (and the outlet relief valve <NUM>). The inner cap <NUM> defines the first airflow pathway <NUM>. The first airflow pathway <NUM> defines a tortuous path from the first opening <NUM> to the inlet relief valve <NUM> such that the airflow path is not straight. Such a configuration may advantageously limit the ability of splashing liquid within the tank volume to make contact with the inlet and outlet relief valves. In the current example, the first airflow pathway <NUM> has a first segment 106a extending in a first axial direction from the first opening <NUM> to the first axial end <NUM> of the vent.

The first airflow pathway <NUM> has a second segment 106b extending from the first airflow pathway <NUM> at first axial end <NUM> of the vent to the inlet relief valve <NUM>. The second segment 106b extends in an opposite axial direction from the first axial direction, meaning that, in operation, there is airflow from the first airflow pathway <NUM> to the second airflow pathway <NUM> (or from the second airflow pathway to the first airflow pathway <NUM>), the airflow in the first segment 106a is in the opposite axial direction of the airflow in the second segment 106b. The opposing axial directions of the first segment 106a and the second segment 106b may advantageously limit liquid particles from traveling from the first segment 106a through the second segment 106b to the valves. The first airflow pathway <NUM> defines a <NUM>-degree turn connecting the first segment 106a and the second segment 106b. The second segment 106b extends <NUM>-degrees from the first segment 106a. The first segment 106a and the second segment 106b are substantially parallel.

In the current example, the first airflow pathway <NUM> is defined from the first axial end <NUM> of the vent housing <NUM> towards the second axial end <NUM> of the vent housing <NUM>. The first axial end <NUM> of the vent housing <NUM> has an outer shell <NUM> and an inner shell <NUM>. The outer shell <NUM> defines the first axial end <NUM> of the vent housing <NUM> and the outer shell <NUM> extends axially towards the second axial end <NUM> of the vent housing <NUM>. The outer shell <NUM> forms an outer lateral boundary about the first segment 106a of the first airflow pathway <NUM>. The inner shell <NUM> defines a shell opening <NUM>. The inner shell <NUM> forms an inner lateral boundary about the first segment 106a and an outer lateral boundary of the second segment 106b of the first airflow pathway <NUM>. The inner shell <NUM> is disposed between the first segment 106a and the second segment 106b in the radial direction. The vertical orientation of the outer lateral boundary of the first segment 106a, the inner lateral boundary of the first segment 106a, and/or the outer lateral body of the second segment 106b may advantageously direct collected liquid down towards a draining pathway to return the liquid to the liquid tank using gravity.

In some embodiments, the first segment 106a and the second segment 106b are defined about a central axial axis x (see <FIG>) of the vent housing <NUM>. In the current example, the first segment 106a and the second segment 106b are concentric along at least a portion of the first airflow pathway <NUM>.

In some embodiments the outer shell <NUM> and the annular sidewall <NUM> are a single, unitary component. However, examples consistent with the current embodiment, the outer shell <NUM> and the annular sidewall <NUM> are separate components that are coupled. The outer shell <NUM> and the annular sidewall <NUM> define a snap fit structure, although they can define other types of connections, as well. In particular, here the outer shell <NUM> has a distal end defining plurality of engagement tabs <NUM> (visible in <FIG> and <FIG>). A connector <NUM> extends axially away from the annular sidewall <NUM> towards the first axial end <NUM> of the vent housing <NUM>. The connector <NUM> defines a plurality of tab retaining openings <NUM> that are each configured to retain an engagement tab <NUM> via an interference fit. Other types of connections are also contemplated including a screw fit, bayonet connector, compression fit, and the like.

In the current example, the inner shell <NUM> has a radial rim <NUM> (visible in <FIG>) on one end that extends radially outward from a main portion of the inner shell <NUM>. The radial rim <NUM> is retained between the distal end of the outer shell <NUM> and the connector <NUM> in the axial direction. The radial rim <NUM> is not positioned between the engagement tabs <NUM> and the tab retaining openings <NUM>, however. Further, in some implementations it may be possible for liquid to splash between the engagement tabs <NUM> and the tab retaining openings <NUM>. The vent housing <NUM> may advantageously be designed to obstruct such liquid intrusion. In particular, the inner shell <NUM> can define one or more barrier walls <NUM> (visible in <FIG>) that radially align with the engagement tabs <NUM> and the tab retaining openings <NUM>. The barrier walls <NUM> can extend axially and laterally around the openings between the engagement tabs <NUM> and the tab retaining openings <NUM> to serve as a physical obstruction to splashing liquid.

It is noted that in the embodiment depicted in <FIG>, the first segment 106a of the first airflow pathway <NUM> additionally has an axial obstruction feature <NUM> that extends laterally across the first airflow pathway <NUM>. The axial obstruction feature <NUM> can be a radial ridge that forms a spiral along the axial length of the first segment 106a of the first airflow pathway <NUM>. In this example the axial obstruction feature <NUM> is a ridge that extends radially outward from the inner shell <NUM> towards the outer shell <NUM>, but in some other examples the axial obstruction feature <NUM> can be a ridge that extends radially inward from the outer shell towards the inner shell <NUM>. In the current example, the axial obstruction feature extends a radial distance that is less than the radial distance between the outer shell <NUM> and the inner shell <NUM>. Such an obstruction feature <NUM> can provide further splash protection.

Additionally or alternatively, as depicted in <FIG>, an axial blocking feature <NUM> can be disposed across the second segment 106b of the first airflow pathway <NUM>. The axial blocking feature <NUM> is configured to provide a physical obstruction to liquid splashing in the axial direction through the second segment 106b, but still allows airflow along the airflow pathway. The axial blocking feature <NUM> can be a ramped radial ridge spiraling axially through the second segment 106b, similar to the axial obstruction feature <NUM> described above. Or, as depicted in the current example, the axial blocking feature <NUM> is a series of rings extending radially outward from a central axial core <NUM>, where the central axial core <NUM> extends axially through the inner shell <NUM>. In various implementations of the current technology an axial obstruction feature <NUM> and/or the axial blocking feature <NUM> can be omitted, which may advantageously reduce the pressure drop across the vent <NUM>.

The first axial end <NUM> of the vent <NUM> defines drain openings <NUM> extending axially through the first axial end <NUM> of the vent. The drain openings <NUM> define a draining pathway extending from the first airflow pathway <NUM> through the first axial end <NUM> of the vent housing <NUM>. The draining pathway and the drain openings <NUM> can allow for gravity-assisted drainage of liquid in the first airflow pathway <NUM>. As such, in various embodiments, the first axial end <NUM> of the vent housing <NUM> is configured to be positioned vertically below the second axial end <NUM> of the vent housing <NUM>. In the current example, the drain openings <NUM> are spaced radially outward from the second segment 106b of the first airflow pathway <NUM> to limit liquid from splashing into the second segment 106b of the first airflow pathway <NUM> through the drain openings <NUM>. A ramped surface <NUM> extends towards the drain openings <NUM> to direct liquid flow towards the drain openings <NUM>.

As mentioned above, the second opening <NUM> of the vent housing <NUM> is configured to be in direct fluid communication with the external environment of the liquid tank. The second opening <NUM> is defined between the outer cap <NUM> and the inner cap <NUM>. The second opening <NUM> is defined between the first axial end <NUM> and the second axial end <NUM> of the vent housing <NUM>. In the current example, the second opening <NUM> forms an annulus extending around the central axis x and/or the central opening. The second opening <NUM> generally faces the first axial end <NUM> of the vent housing <NUM> and, upon installation of the vent to a liquid tank, the second opening <NUM> is configured to face an outer surface of the liquid tank. Such a configuration may advantageously obstruct debris such as water in the outside environment from directly entering the second airflow pathway <NUM> through the second opening <NUM>. The outer cap <NUM> forms a barrier circumferentially around the second airflow pathway <NUM> and laterally across the second airflow pathway <NUM> to obstruct outside debris from directly entering the second airflow pathway <NUM>.

At least a portion of the second airflow pathway <NUM> is configured to be tortuous such that the fluid path from the second opening <NUM> to the filter assembly <NUM> is not straight. Such a configuration may advantageously prevent splashing liquids from in the outside environment from making contact with the filter assembly <NUM>. Indeed, in the current example, the second airflow pathway <NUM> extends from the second opening <NUM> in the axial direction towards the second axial end <NUM> of the vent and then in the radial direction towards and through the filter assembly <NUM>. In various embodiments, the second airflow pathway <NUM> defines at least an axially extending segment 108a and a radially extending segment 108b (depicted in <FIG>).

In various embodiments a tank interface <NUM> assembly can be used to sealably couple the vent to the tank. <FIG> depicts a cross-sectional exploded view of an example implementation of a vent system and a portion of a liquid tank. <FIG> depicts a perspective view of a tank interface <NUM> consistent with <FIG>. The tank interface <NUM> is generally configured to be fixed to a liquid tank <NUM> in a sealed relationship about a tank opening <NUM>. The tank interface <NUM> is configured to seal to a vent <NUM> such that the vent <NUM> is sealed to the liquid tank <NUM>. The tank interface <NUM> is generally configured to be used in conjunction with vents described herein.

The tank interface <NUM> generally has a vent mount <NUM>. The vent mount <NUM> is configured to be fixed to a liquid tank. In particular, the vent mount <NUM> defines an annular body <NUM> defining an annular outer surface <NUM> that is configured to be sealed to the tank <NUM> about a tank opening <NUM>. A seal <NUM> is disposed between the annular outer surface <NUM> and the tank <NUM> about the tank opening <NUM>. The vent mount <NUM> defines a mount opening <NUM> and a mating structure <NUM>. The mount opening <NUM> is configured to substantially align with the tank opening <NUM>. The mount opening <NUM> and the tank opening <NUM> are configured to receive the first axial end <NUM> of the vent <NUM> upon installation of the vent <NUM>.

The mating structure <NUM> of the vent mount <NUM> is configured to sealably mate with the mounting structure <NUM> of the vent <NUM> around the vent housing <NUM>. In this example that is consistent with the vents depicted herein, the mating structure <NUM> includes a bayonet connector <NUM> that is configured to reversibly receive the bayonet coupler <NUM> of the vent. In the current example, the mating structure <NUM> has two bayonet connectors <NUM>. In some other embodiments additional bayonet connectors <NUM> can be included. The tank interface <NUM> has a circumferential wall <NUM> extending axially outward from the annular body <NUM>. The distal end <NUM> of the circumferential wall <NUM> defines the bayonet connectors <NUM>. To couple the vent <NUM> to the vent mount <NUM>, the first axial end <NUM> of the vent is inserted through the mount opening <NUM> and the bayonet couplers <NUM> are brought into axial alignment with the bayonet connectors, and the vent <NUM> is rotated relative to the vent mount <NUM> such that the bayonet couplers <NUM> and bayonet connectors <NUM> mutually engage. Consistently with examples described herein, to bring the bayonet couplers <NUM> and bayonet connectors <NUM> into axial alignment, the distal end <NUM> of the circumferential wall <NUM> is inserted into the first airflow pathway <NUM> between the outer cap <NUM> and the inner cap <NUM>. Such a connection is shown in <FIG>, which is a cross-sectional view of an example vent <NUM> installed in the example vent mount <NUM> of <FIG>.

The mating structure <NUM> of the vent mount <NUM> also has a vent sealing surface <NUM>. The vent sealing surface <NUM> is configured to sealingly engage a surface of the vent <NUM> around the vent housing <NUM>. In particular, the vent sealing surface <NUM> can be configured to fluidly separate the first opening <NUM> and the second opening <NUM> outside of the vent <NUM>. In the current example, the vent sealing surface <NUM> is configured to seal against the sealing flange <NUM> (discussed above, see <FIG>, for example), which is visible in <FIG> and <FIG>. The vent sealing surface <NUM> can be configured to seal against the sealing flange <NUM> around the inner cap <NUM> of the vent housing <NUM>, in some embodiments. In this example, the vent sealing surface <NUM> is an inner radial surface defined by the circumferential wall <NUM> of the vent mount <NUM>. In some other embodiments the vent sealing surface <NUM> can be an axial surface where the sealing flange supports an axial seal.

The mating structure <NUM> of the vent mount <NUM> and the mounting structure <NUM> of the vent <NUM> can have alternate configurations. In some examples the mating structure (<NUM>) and the mounting structure (<NUM>) can have a frictional fit or an interference fit. In some embodiments the mating structure and the mounting structure form a snap fit connection. In some embodiments the mating structure and the mounting structure have a threaded connection. For example, the sealing flange <NUM> can define outer circumferential threads that are configured to engage mating inner circumferential threads defined by the vent sealing surface <NUM> of the vent mount <NUM>. As another example the outer cap <NUM> can define inner circumferential threads that are configuration to engage mating outer circumferential threads defined by the outer circumferential wall <NUM> of the vent mount <NUM>. In such an example, the inner circumferential threads and outer circumferential threads can define gaps that accommodate airflow. Such gaps can define a portion of the second airflow pathway <NUM>.

In various embodiments the vent mount <NUM> can incorporate structural features that help prevent entry to debris, such as spraying liquid, in the vent. For example, as visible in <FIG>, the vent mount <NUM> incorporates a series of radially extending deflectors <NUM>. The radially extending deflectors <NUM> are disposed along the outer surface of the circumferential wall <NUM>. The deflectors <NUM> extend radially outward from the outer surface of the circumferential wall <NUM>. The deflectors <NUM> are configured to partially obstruct the second opening <NUM> across the axial direction. The configuration of the deflectors <NUM> across the second airflow pathway <NUM> is visible in <FIG>, which is another cross-sectional view of the system of <FIG> through a second cross section. The inner surface of the circumferential wall <NUM> is in sealing engagement with the sealing flange of the inner cap <NUM>, and the circumferential wall <NUM> extends a portion of the distance of the radial gap between the inner cap <NUM> and the outer cap <NUM>. The deflectors <NUM> extend from the outer surface of the circumferential wall <NUM> across a further portion of the distance of the radial gap between the inner cap <NUM> and the outer cap <NUM> across the second airflow pathway <NUM>.

The series of deflectors <NUM> are positioned circumferentially about the vent mount <NUM> between the bayonet connectors <NUM>. As is visible in <FIG>, the bayonet connectors <NUM> and bayonet couplers <NUM> form a physical obstruction laterally across the second airflow pathway <NUM>. As such, in some embodiments the outer circumferential surface of the vent mount <NUM> may lack radial deflectors <NUM> along portions of the circumferential wall <NUM> that are in axial alignment with a bayonet connector <NUM>. In some other embodiments such deflectors <NUM> can be spaced across the entire outer circumferential surface of the circumferential wall <NUM>.

<FIG> depicts a facing view of a portion of the radial deflectors <NUM> on the vent mount <NUM>. In the current example, each deflector <NUM> extends diagonally across the outer radial surface of the vent mount <NUM>. The diagonal orientation can contribute to the gravity assisted drainage of liquid out of the second airflow pathway <NUM> through the second opening <NUM>. Furthermore, in the current example, each end <NUM> of each radially extending deflector <NUM> is axially aligned with an end <NUM> of each adjacent radially extending deflector <NUM>. The first and last radially extending deflectors <NUM> in the series each have an end <NUM> that is in axial alignment with the bayonet connector <NUM>. As such, the combination of the deflectors <NUM> and the bayonet connectors <NUM> form a substantially continuous obstruction in the second airflow pathway <NUM> about the vent housing <NUM>. Such a configuration may advantageously obstruct entrance of liquid into the second airflow pathway <NUM> while accommodating airflow.

<FIG>, <FIG> and <FIG> depict an example tank interface <NUM> having an optional strainer <NUM> feature. The strainer <NUM> is generally configured to be installed in a tank opening in implementations where the tank opening can be used as a fill port for filling the tank with liquid, such as hydraulic fluid. In such implementations the strainer <NUM> can be configured to filter out relatively large contaminants such as particulates, broken components, and the like. The strainer <NUM> is also configured to surround the first axial end <NUM> of the vent <NUM>. The strainer <NUM> generally has a strainer body <NUM> formed from a material such as a plastic mesh, wire mesh or filtration media. The strainer body <NUM> extends in the axial direction and defines an axial end <NUM> (the proximal end). As such, liquid that passes through the tank opening necessarily passes through the strainer body <NUM>. Along the axial length of the strainer body <NUM>, the strainer body <NUM> has a maximum lateral dimension (perpendicular to the axial direction) that is less than the diameter of the mount opening <NUM>. The lateral dimension can be a diameter, for example. As such, the strainer body <NUM> can be inserted through the mount opening <NUM>.

Claim 1:
A vent (<NUM>) comprising:
a vent housing (<NUM>) defining a mounting structure (<NUM>), a first axial end (<NUM>), a second axial end (<NUM>), a first opening (<NUM>) between the first axial end (<NUM>) and the second axial end (<NUM>), a first airflow pathway (<NUM>) extending from the first opening (<NUM>), a second opening (<NUM>), a second airflow pathway (<NUM>) extending from the second opening (<NUM>), and a draining pathway extending from the first airflow pathway (<NUM>) through the first axial end (<NUM>) of the vent housing (<NUM>), wherein the first airflow pathway (<NUM>) has a first segment (106a) extending in a first axial direction and a second segment (106b) extending in an opposite axial direction from the first axial direction;
an inlet relief valve (<NUM>) coupled to the housing between the first airflow pathway (<NUM>) and the second airflow pathway (<NUM>), wherein the inlet relief valve (<NUM>) is biased in a closed position and is configured to open upon a pressure differential of the second airflow pathway (<NUM>) relative to the first airflow pathway (<NUM>) exceeding a first threshold pressure, wherein the second segment extends from the first segment to the inlet relief valve (<NUM>);
an outlet relief valve (<NUM>) coupled to the housing between the first airflow pathway (<NUM>) and the second airflow pathway (<NUM>), wherein the outlet relief valve (<NUM>) is biased in a closed position, wherein the outlet relief valve (<NUM>) is arranged in parallel with the inlet relief valve (<NUM>) and wherein the outlet relief valve (<NUM>) is configured to open upon a pressure differential of the first airflow pathway (<NUM>) relative to the second airflow pathway (<NUM>) exceeding a second threshold pressure; and
a filter assembly (<NUM>) disposed in the vent housing (<NUM>), wherein the filter assembly extends across the second airflow pathway (<NUM>).