Patent Description:
The cavity of the main body contains a lubricant to facilitate operation of, for example, the bearings. The lubricant may be oil or grease. The main body may be bounded, on the outboard side, with a sight window such that the level of the oil or grease may be viewed and monitored. Lubricant may be added as necessary depending on the level shown in the one or more sight windows.

During operation, the lubricant heats. The heat can induce an increase in pressure within the cavity. Thus, it is desirable to provide a vent (sometimes referred to as a vent path) to allow pressure equalization between the cavity and the environment, which is typically the atmosphere. <CIT> discloses a hubcap with a vented closure in which a chamber is formed between the hubcap and the wheel for housing a lubricating fluid for the associated wheel bearings. A vent passage extending through the hubcap is provided for relieving the pressure formed in the chamber. <CIT> does not disclose a shield coupled to the inboard side of a vent plug body.

Venting the wheel end assembly, however, has several drawbacks. One of the several drawbacks includes that the vent can provide a leak path allowing oil to egress to the environment. The vent also provides a leak path allowing foreign matter, such as, dirt, water, or the like, to ingress to the cavity. The foreign matter can foul the lubricant and potentially damage the parts of the wheel end assembly including, for example, the bearings. The vent is typically about the outboard end cap of the hub assembly and may be in a plug in the end cap where the plug has a vent path, sometimes referred to as a vent plug.

To inhibit ingress of foreign matter and egress of oil, the vent path, whether in a plug or not, may provide a labyrinth or tortuous path between the cavity and the environment, or atmosphere. The vent may also include a diaphragm or valve that normally isolates the cavity from the atmosphere but places the cavity and atmosphere in fluid communicate (via the vent) when the pressure in the cavity exceeds a predefined threshold.

Improvements to the vent, however, are desirable. Thus, against this background, an improved vent is provided.

This Summary, and the foregoing Background, is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the invention, which is defined by the claimed subject matter.

In some aspects of the technology, a vent plug for a hub cap as defined in appended claim <NUM> is provided. The vent plug includes a cover and base forming a chamber. A vent plug body extends from the base and forms a cavity. The base has at least an aperture to receive a valve. The valve selectively opens and closes to place the cavity in fluid communication with the chamber. A shield is coupled to the vent plug body. The shield comprises an annularly extending disc that traverses the cavity. The shield includes a connecting surface to connect the shield to the vent plug body. The shield provides a lubrication/liquid barrier to inhibit lubrication (or other liquid) from entering the cavity formed by the vent plug body and the chamber. The connection between the shield and the vent plug body allows a gas (typically air) to vent past the shield into the cavity and, when pressure is sufficiently high, to the chamber and eventually atmosphere.

These and other aspects of the present system and method will be apparent after consideration of the Detailed Description and Figures herein.

Non-limiting and non-exhaustive embodiments of the present invention, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

The technology of the present application will now be described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the technology of the present application. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense.

The technology of the present application is described with specific reference to a hub cap with a vent plug for a steer or trailer. However, the technology described herein may be used for other vehicles wheel ends, such as, for example, tractors, cars, airplane landing gear, and the like. The technology also can be used to vent drive axles. Moreover, the technology of the present application will be described with relation to exemplary embodiments.

A hub cap <NUM> is shown in <FIG>. The hub cap <NUM> as shown is a hub cap that is currently available from Stemco Products, Inc. The hub cap <NUM> as shown has a generally cylindrical body <NUM> with an inboard side <NUM> and an outboard side <NUM>. The inboard side <NUM> has a flanged surface <NUM> having a plurality of bolt holes <NUM> to allow the hub cap <NUM> to be bolted to the wheel end. The outboard side <NUM> has a sight glass <NUM> and an end ring <NUM>. The end ring <NUM> has bores <NUM> that receive fasteners <NUM> to couple the end ring <NUM>, sight glass <NUM>, and seals <NUM> to the outboard side <NUM> of the hub cap <NUM>. The fasteners may be rivets, screws, pins, or the like. In some embodiments, the end ring <NUM> and sight glass <NUM> may be integral with the outboard side <NUM> of the hub cap <NUM>, which would remove the need for the bores <NUM>, fasteners <NUM>, and seals.

The sight glass <NUM> and end ring <NUM> provide an aperture <NUM>. A vent plug <NUM> is provided in the aperture <NUM>. The vent plug <NUM> has a cover <NUM> that is coupled to a base <NUM>. The junction of the cover <NUM> and base <NUM> is at an interface <NUM>. As can be appreciated, the vent plug <NUM> is located at the geometric center of the hub cap <NUM>. In other embodiments, the vent plug <NUM> may be located off-center. In still other embodiments, a plurality of vent plugs may be provided at symmetrical or asymmetrical locations.

<FIG> shows a cross sectional view of the vent plug <NUM> in isolation. The vent plug has the cover <NUM> coupled to the base <NUM>. The base <NUM> has an outer edge surface <NUM> and a boarder wall <NUM> that form a shelf or ledge. The outer edge surface <NUM> has a width W1. The boarder wall <NUM> has an outer diameter D1. The cover <NUM> has a concave dome <NUM> and a rim <NUM> at the outer edge <NUM> of the dome <NUM>. The rim <NUM> has a width W2. The rim <NUM> has an inner diameter D2 slightly smaller than the outer diameter D <NUM> such that a frictional engagement is maintained between the boarder wall <NUM> and the rim <NUM> to hold the cover <NUM> to the base <NUM>. However, as shown in <FIG>, the inner diameter D2 of the rim <NUM> may be slightly stretched to be greater than the outer diameter D1 when installed to form the interference fit. An interface <NUM> between the cover <NUM> and the base <NUM> is formed by the boarder wall <NUM>, outer edge surface <NUM>, and the rim <NUM>. Notice, in certain aspects, the cover <NUM> and the base <NUM> may be a single unit. If formed as a monolithic or single unit, the interface <NUM> may be replaced with perforations or the like. While shown as a friction fit, the cover <NUM> and the base <NUM> could be coupled using other coupling techniques such as, for example, welding (sonic or heat), adhering, gluing, curing, or the like.

The cover <NUM> and the base <NUM> define a chamber <NUM>. The cover <NUM> has a plurality of ribs <NUM>, defining concentric rings, that extend into the chamber <NUM> towards the base <NUM>. The base <NUM> has a plurality of ribs <NUM>, defining concentric rings, that extend into the chamber <NUM> towards the cover <NUM>. The ribs <NUM> of the cover <NUM> and the ribs <NUM> of the base <NUM> are generally alternating and define a labyrinth path <NUM> between a central aperture <NUM> in the base <NUM> and the interface <NUM>. The labyrinth path <NUM> provides a tortuous vent path that allows gas to travel relatively freely, but inhibits liquids from leaking through the path, which inhibits the lubrication from exiting to the atmosphere. The base <NUM> further includes radially outward spaced apart apertures <NUM>. The spaced apart apertures <NUM> allow air to vent into the lubrication cavity of the wheel end to inhibit the creation of a vacuum as the bearings and lubrication cool during periods of non-use.

A valve <NUM> resides in the central aperture <NUM>. The valve <NUM> is an elastic member and typically formed of an elastomeric. The valve <NUM> is further described in <CIT>, which is owned by Stemco. Generally, the valve <NUM> is designed such that the vent is normally closed until the pressure in the wheel end increases due to operation (or other reasons). When pressure exceeds a set point, the valve opens to allow pressure to vent.

The base <NUM> is coupled to the vent plug body <NUM>. The vent plug body <NUM> extends in an inboard direction from the base <NUM> forming a generally cylindrical, hollow cavity <NUM>. The vent plug body <NUM> defines an inner diameter D3 although the vent plug body <NUM> may be cylindrical or frustoconical as shown. The outer surface <NUM> of the vent plug body <NUM> forms one or more annular glands <NUM>, of which two annular glands <NUM> are shown. Seals <NUM>, such as o-rings, form a seal between the vent plug <NUM> and the hub cap <NUM>, more specifically, the sight glass <NUM>. The annular glands <NUM> are generally formed with a portion of the vent plug body <NUM> forming the base of the annular gland <NUM> and one or more radially extending, annular ribs <NUM> forming walls of the annular gland <NUM>.

A shield <NUM> is coupled to the inboard side <NUM> of the vent plug body <NUM>, which is distal to the base <NUM>. The shield <NUM>, as shown in <FIG>, has a radially extending disc body <NUM> and an axially extending connector ring <NUM> with a radially extending annular connecting surface <NUM>. The disc body <NUM> has a shape to cooperatively work with the shape of the vent plug body <NUM>. The radially extending annular connecting surface <NUM> has one or more bores <NUM>. The radially extending disc body <NUM> has a diameter D4 slightly less than the corresponding diameter D3 of the vent plug body <NUM>. <FIG> shows a perspective view of the vent shield <NUM>. The disc body <NUM> and the connector ring <NUM> are generally solid to inhibit lubricant from traversing from the lubrication cavity of the wheel end assembly to the cavity <NUM> of the vent plug <NUM>. The connector ring <NUM> may have cutouts <NUM> to facilitate a gas vent path.

With reference back to <FIG> and <FIG>, the inboard side <NUM> of the vent plug body <NUM> provides connector protrusions <NUM>. The connector protrusions <NUM> have an axially extending leg <NUM> and a radially extending ledge <NUM>. The connector protrusions <NUM> align with the bores <NUM> in connecting surface <NUM>. The terminal end <NUM> of the connector protrusions <NUM> may be tapered or chamfered to facilitate inserting the connector protrusions <NUM> into the bores <NUM>. Once the ledge <NUM> clears the bore <NUM>, the elastic connector protrusion <NUM> moves the ledge <NUM> to engage the underside <NUM> of the connecting surface <NUM> forming a snap fit connection in this exemplary embodiment. While a snap fit connection is shown in this exemplary embodiment as a means for connecting the shield to the vent plug body, the connection between the shield <NUM> and the vent plug body <NUM> may be formed by alternative means, such as, for example, a friction fitting, adhesive, glues, welds, or the like. Moreover, the shield may be molded with the vent plug body to form a monolithic piece.

As can be appreciated, the shield <NUM> connection to the vent plug body <NUM> provides a leak path for gas (air) from the inboard wheel end to the vent plug body <NUM>, and eventually to atmosphere through interface <NUM>.

<FIG> shows an alternative version of the shield <NUM>'. Shield <NUM>' has a radially extending disc portion <NUM>' and a radially extending annular connector surface <NUM>' extending from an edge <NUM>' of the disc portion <NUM>'. The connector surface <NUM>' may include bores <NUM>' to receive the connector protrusions <NUM>. The shield <NUM>' includes vent channels <NUM>' to facilitate air flow. The vent channels <NUM>' may be incorporated into other shields described herein.

<FIG> shows alternative vent plugs <NUM>, <NUM>, <NUM>, and <NUM> with a shield <NUM>, <NUM>, <NUM>, and <NUM>. As shown, vent plugs <NUM>, <NUM>, and <NUM> provide a valve <NUM> but as shown by vent plug <NUM>, a valve <NUM> is not a necessary component of the vent plug. The shields <NUM>, <NUM>', <NUM>, <NUM>, <NUM>, and <NUM> inhibit the flow of lubricant into the vent plug body <NUM>. The shield <NUM> includes an axially extending central member <NUM> that engages with the valve <NUM>.

<FIG> shows a vent plug <NUM> with a shield <NUM> and a vent plug <NUM> with a shield <NUM>. Placement of the shield <NUM> inside the vent plug body is shown towards the middle or outboard end <NUM> of the vent plug <NUM>. The specific placement of the shield <NUM> may vary depending on the characteristics and/or material of the vent plug <NUM>. Placement of shield <NUM> in vent plug <NUM> is toward the inboard end <NUM>. In other words, the placement of the various shields described herein may be optimized for the particular construction of the vent plug.

<FIG> shows a detail of means for connecting the vent plug body to the shield. A portion of a vent plug body <NUM> is shown. The vent plug body <NUM> terminates, at the inboard side <NUM>, with a shoulder <NUM>. The shoulder <NUM> is formed by a radially extending annular surface <NUM> and an axially extending annular rim <NUM>. The shield <NUM> has a radially extending annular ledge <NUM> that mates with the shoulder <NUM> and forms a junction <NUM>. The shield <NUM> is coupled, in this exemplary embodiment, to the vent plug body <NUM> by a weld at points along junction <NUM>.

<FIG> provides an alternative construction of a vent plug <NUM> with a shield <NUM>. The vent plug <NUM> includes a cover <NUM> and a base <NUM>. The cover <NUM> and base <NUM> would have annular concentric rings as described above, but not shown here, to provide a labyrinth seal. The vent plug <NUM> includes a valve <NUM>, which is similar to the valve <NUM> described above.

The vent plug <NUM> further includes an annular vent plug body <NUM> extending in an inboard direction from the base <NUM>. The vent plug body <NUM> includes one or more annular glands <NUM>, which are formed in part by an outer surface <NUM> of the vent plug body <NUM> and radially extending, annular rib <NUM>. The shield <NUM> traverses the space <NUM> defined by the vent plug body <NUM>. The shield <NUM> has perforations <NUM> that provide a vent path from the wheel end lubrication cavity to the space <NUM>. While the shield <NUM> may be a disc that traverses the space <NUM>, the exemplary shield <NUM> shown provides a central member <NUM> extending in an axial, outboard direction. The central member <NUM> is shown as a cylindrical member with a distal protrusion <NUM> that is sized to fit within a bore <NUM> of the valve <NUM>. The central member <NUM> and protrusion <NUM> fitting within the bore <NUM> of the valve <NUM> provides for support among other things from the shield <NUM>.

The vent plugs with shields, as described herein, generally provide a liquid barrier and a gas vent path. <FIG> shows an exemplary vent path A for a vent plug <NUM> having a shield <NUM>. <FIG> shows an exemplary vent path B for a vent plug <NUM> having a shield <NUM>'.

Claim 1:
A vent plug (<NUM>) for a hub cap (<NUM>) comprising,
a cover (<NUM>);
a base (<NUM>) coupled to the cover and defining an interface (<NUM>), the base being inboard of the cover;
a chamber (<NUM>) between and defined by the cover and the base;
an annular vent plug body (<NUM>) coupled to the base and extending in an inboard direction from the base where the base and the annular vent plug body define a hollow cavity (<NUM>);
a shield (<NUM>, <NUM>') coupled to the inboard side of the vent plug body and inboard of the base, the shield generally traversing the hollow cavity defined by the annular vent plug body, wherein
a vent path (A, B) configured to place a lubrication cavity of a wheel end assembly in fluid communication with the hollow cavity that inhibits liquid leaking between the wheel end assembly and the hollow cavity of the vent plug.