Air Dryer Apparatus for a Vehicle Air Brake Charging System

An air dryer apparatus is provided for a vehicle air brake charging system. The air dryer apparatus comprises an air dryer governor assembly. The air dryer governor assembly includes a plastic sleeve having an external sleeve surface and an internal sleeve surface that defines a piston bore. The air dryer governor assembly also includes a piston disposed in the piston bore and slidable along the internal sleeve surface between a preset cut-out setting and a preset cut-in setting of the air dryer governor assembly. The air dryer governor assembly further includes one or more ribs disposed on the external sleeve surface to prevent deformation of the plastic sleeve when the piston slides along the internal sleeve surface between the preset cut-out and cut-in settings.

BACKGROUND

The present application relates to vehicle air brake charging systems, and is particularly directed to an air dryer apparatus for a vehicle air brake charging system, such as a truck air brake charging system.

A truck air brake charging system includes a vehicle air compressor which builds air pressure for an air braking system. The compressor is typically lubricated by an engine oil supply. A governor controls system air pressure between a preset maximum and minimum pressure level by monitoring the air pressure in a supply reservoir. When the supply reservoir air pressure becomes greater than that of a preset “cut-out” setting of the governor, the governor controls the compressor to stop the compressor from building air and also causes an air dryer downstream from the compressor to go into a purge cycle. As the supply reservoir air pressure drops to a preset “cut-in” setting of the governor, the governor returns the compressor back to building air and the air dryer to the charge cycle.

The air dryer is an in-line filtration system that collects and removes both water vapor and oil droplets from the compressor discharge air after it leaves the compressor. This results in cleaner, drier air being supplied to the air braking system, increases the life of the components of the brake assembly, and aids in the prevention of air line and component freeze ups in winter weather. The air dryer typically uses a replaceable “spin on” cartridge containing a desiccant material and an oil separator. Most of the oil droplets are removed by the oil separator as the air passes through the inlet tube into the air dryer. The air then moves through the desiccant material which adsorbs most of the water vapor.

When the air pressure in the supply reservoir reaches the preset cut-out setting of the governor, the governor makes the compressor stop building air and allows the air dryer's “purge cycle” to begin. During the purge cycle, the desiccant material is regenerated (i.e., its ability to remove water is renewed) by a reversal of the saturation process. A small amount of dry air passes back through the desiccant material and the water that has been collected, as well as any oil droplets collected by the oil separator, are purged out through a purge valve to atmosphere.

Some air dryers include a fully integrated governor. In these air dryers, the air dryer includes an air dryer housing having a bore in which a governor assembly is disposed. The governor assembly includes a metallic sleeve in which a piston slides between different positions to provide the preset cut-out (130 psi) and the preset cut-in settings of the governor. The metallic sleeve is located in the bore to maintain the piston and other internal components in place relative to the air dryer housing.

During operation of the vehicle air brake charging system, the governor cycles many times between the preset cut-out setting and the preset cut-in setting. Due to normal wear and tear of components, the governor assembly needs to be replaced from time to time. Accordingly, those skilled in the art continue with research and development efforts in the field of air dryers and governors for vehicle air brake charging systems.

SUMMARY

In accordance with one embodiment, an air dryer apparatus is provided for a vehicle air brake charging system. The air dryer apparatus comprises an air dryer governor assembly. The air dryer governor assembly includes a plastic sleeve having an external sleeve surface and an internal sleeve surface that defines a piston bore. The air dryer governor assembly also includes a piston disposed in the piston bore and slidable along the internal sleeve surface between a preset cut-out setting and a preset cut-in setting of the air dryer governor assembly. The air dryer governor assembly further includes one or more ribs disposed on the external sleeve surface to prevent deformation of the plastic sleeve when the piston slides along the internal sleeve surface between the preset cut-out and cut-in settings.

In accordance with another embodiment, an air dryer apparatus is provided for a vehicle air brake charging system. The air dryer apparatus comprises an air dryer having a housing surface that defines a governor bore. The air dryer apparatus further comprises an air dryer governor assembly disposed in the governor bore. The air dryer governor assembly includes a governor sleeve having an internal sleeve surface that defines a piston bore and an external sleeve surface that faces the housing surface of the air dryer. The air dryer governor assembly also includes a governor piston disposed in the piston bore and slidable along the internal sleeve surface between a preset cut-out setting and a preset cut-in setting of the air dryer governor assembly. The air dryer governor assembly further includes one or more ribs disposed on the external sleeve surface and abutting against the housing surface of the air dryer to prevent deformation of the governor sleeve when the governor piston slides along the internal sleeve surface between the preset cut-out and cut-in settings.

In accordance with yet another embodiment, an air dryer apparatus is provided for a vehicle air brake charging system. The air dryer apparatus comprises a substantially cylinder-shaped governor sleeve having an external sleeve surface and an internal sleeve surface that defines a piston bore. The air dryer apparatus also comprises a governor piston disposed in the piston bore and slidable along the internal sleeve surface between a preset cut-out setting and a preset cut-in setting. The air dryer apparatus further comprises stiffening means disposed on the external sleeve surface and for, providing stiffness of the sleeve to prevent deformation of the governor sleeve when the governor piston slides along the internal sleeve surface between the preset cut-out and cut-in settings.

In accordance with still another embodiment, an apparatus is provided for a vehicle system. The apparatus comprises a substantially cylinder-shaped sleeve having an external sleeve surface and an internal sleeve surface that defines a piston bore. The apparatus also comprises a piston disposed in the piston bore and slidable along the internal sleeve surface between opposite end positions. The apparatus further comprises one or more ribs disposed on the external sleeve surface and for, preventing deformation of the sleeve when the piston slides along the internal sleeve surface between the opposite positions. The sleeve and the one or more ribs comprise a nylon material, and each of the one or more ribs is reinforced with glass fibers that are oriented in a direction substantially parallel to a longitudinal central axis of the piston.

DETAILED DESCRIPTION

The present application is directed to an apparatus for a vehicle system. The specific construction of the apparatus and the industry in which the apparatus is implemented may vary. It is to be understood that the disclosure below provides a number of embodiments or examples for implementing different features of various embodiments. Specific examples of components and arrangements are described to simplify the present disclosure. These are merely examples and are not intended to be limiting. By way of example, an air dryer apparatus for a vehicle air brake charging system, such as a truck air brake charging system, is described herein.

Referring toFIG.1, a perspective view of an air dryer apparatus100constructed in accordance with an embodiment is illustrated. The air dryer apparatus100comprises an air dryer housing110and a replaceable filtration cartridge112that is attached to the air dryer housing110. An air dryer governor assembly120, shown in heavier, darker lines inFIG.1, is disposed inside the air dryer housing110. Structure and operation of air dryers are known and, therefore, will not be described.

Referring toFIG.2, an enlarged sectional view of a portion of the air dryer apparatus100ofFIG.1, designated approximately with rectangle “2” shown inFIG.1, is illustrated. The air dryer housing110has a housing surface114that defines a governor bore116in which the air dryer governor assembly120is disposed. The air dryer governor assembly120includes a substantially cylinder-shaped plastic governor sleeve122having a body portion123. The plastic governor sleeve122has an external sleeve surface124and an internal sleeve surface126that defines a piston bore128. The external sleeve surface124faces the housing surface114of the air dryer housing110. The external sleeve surface124has an end portion124a, an opposite end portion124c, and a central portion124bthat interconnects the end portions124a,124c.

The air dryer governor assembly120also includes a governor piston130disposed in the piston bore128. The governor piston130is slidable along the internal sleeve surface126between a preset cut-out setting and a preset cut-in setting of the air dryer governor assembly120. The governor piston130has a longitudinal central axis132along which the governor piston130slides between the preset cut-out setting and the preset cut-in setting.

Referring toFIG.3, a perspective view of the plastic governor sleeve122used in the air dryer governor assembly120in accordance with an embodiment is illustrated.FIG.4is a sectional view taken approximately along line4-4shown inFIG.3, and showing the internal sleeve surface126of the plastic governor sleeve122. Inner diameter of the plastic governor sleeve122in the vicinity of surface portion126ais in a range between about 1.226 in (31.145 mm) and about 1.241 in (31.520 mm). Inner diameter of the plastic governor sleeve122in the vicinity of surface portion126bis in a range between about 1.253 n (31.826 mm) and about 1.275 in (32.385 mm). Inner diameter of the plastic governor sleeve122in the vicinity of surface portion126cis in a range between about 1.310 in (33.274 mm) and about 1.332 in (33.830 mm). The inner diameter of the plastic governor sleeve122gradually increases from left to right (as viewed looking atFIG.4) to form a generally diverging conical shape, similar to a draft tube.

Outer diameter of the plastic governor sleeve122in the vicinity of the end portion124ais in a range between about 1.44 in (36.576 mm) and about 1.46 in (37.084 mm). Outer diameter of the plastic governor sleeve122in the vicinity of the opposite end portion124cis in a range between about 1.46 in (37.084 mm) and about 1.54 in (39.116 mm). Axial length of the plastic governor sleeve122is in a range between about 3.79 in (90.26 mm) and about 3.81 in (96.77 mm).

Three sets of ribs150,160,170are axially spaced apart from each other along the longitudinal central axis132of the governor piston130. Axial distance between the set of ribs150and the set of ribs160is in a range between about 1.54 in (39.116 mm) and about 1.58 in (40.132 mm). Axial distance between the set of ribs160and the set of ribs170is in a range between about 0.17 in (4.318 mm) and about 0.21 in (5.334 mm). In a preferred embodiment, the axial distance between the set of ribs150and the set of ribs160is about 1.56 in (39.624 mm), and the axial distance between the set of ribs160and the set of ribs170is about 0.19 in (4.826 mm).

Although three sets of ribs150,160,170are shown inFIGS.3and4in a preferred embodiment, it is conceivable that any number of sets of ribs be disposed on the external sleeve surface124and axially spaced apart from each other along the longitudinal central axis132. The structure and functionality of each of the three sets of ribs150,160,170are similar. For simplicity and purpose of explanation, only the one set of ribs150is described in detail herein.

Referring toFIG.5, a sectional view taken approximately along line5-5shown inFIG.3is illustrated. More specifically,FIG.5shows an arrangement of the one set of ribs150on the external sleeve surface124of the plastic governor sleeve122. The set of ribs150extends around the longitudinal central axis132of the governor piston130. The set of ribs150includes three separate ribs151,152,153that are circumferentially spaced apart from each other around the longitudinal central axis132of the governor piston130. Each of the ribs151,152,153abuts against the housing surface114(FIG.2) of the air dryer housing110.

Circumferential length of each of the ribs151,152,153is in a range between about 0.500 in (12.70 mm) and about 0.552 in (14.02 mm). Circumferential distance between an end of one of the ribs151,152,153and an end of another one of the ribs151,152,153is in a range between about 0.96 in (24.384 mm) and about 1.06 in (26.924 mm). In a preferred embodiment, the circumferential length of the rib151is about 1.508 in (38.303 mm), the circumferential length of the rib152is about 1.508 in (38.303 mm), the circumferential length of the rib153is about 1.508 in (38.303 mm), the circumferential distance between one end of rib151and one end of rib152is about 1.012 in (25.705 mm), the circumferential distance between one end of rib152and one end of rib153is about 1.012 in (25.705 mm), and the circumferential distance between one end of rib151and one end of rib153is about 1.012 in (25.705 mm).

Although three separate ribs151,152,153are shown inFIG.5in a preferred embodiment, it is conceivable that the set of ribs150comprises any number of separate ribs that extend around the longitudinal central axis132. The structure and functionality of each of the ribs151,152,153are similar. For simplicity and purpose of explanation, only the one rib151is described in detail herein.

Referring toFIG.6, details of a cross-sectional profile of the individual rib151on the external sleeve surface124of the plastic governor sleeve122are shown. Height (i.e., thickness) of the rib151is in a range between about 0.025 in (0.635 mm) and about 0.035 in (0.889 mm), and the cross-sectional profile is substantially half-moon shaped. In a preferred embodiment, the height of the rib151is about 0.03 in (0.762 mm), and the cross-sectional profile is substantially half-moon shaped, such as shown inFIG.6. The half-moon shape may be more oblong or less oblong than as shown inFIG.6. Other cross-sectional profiles of the individual rib151are possible.

Referring toFIG.6A, details of a cross-sectional profile of an individual rib161of the set of ribs160and an individual rib171of the set of ribs170on the external sleeve surface124of the plastic governor sleeve122are shown. Height (i.e., thickness) of each of the ribs161,171is in a range between about 0.015 in (0.381 mm) and about 0.025 in (0.635 mm), and the cross-sectional profile is substantially half-moon shaped. In a preferred embodiment, the height of each of the ribs161,171is about 0.02 in (0.508 mm), and the cross-sectional profile is substantially half-moon shaped, such as shown inFIG.6A. The half-moon shape may be more oblong or less oblong than as shown inFIG.6A. Other cross-sectional profiles of each of the individual ribs161,171are possible.

The three separate ribs151,152,153of the set of ribs150are larger than the three separate ribs of each of the other two sets of ribs160,170. As best shown inFIG.3, only two separate ribs161,162of the set of ribs160and only two separate ribs171,172of the set of ribs170are visible. The third rib of the set of ribs160and the third rib of the set of ribs170are hidden from view inFIG.3. The three larger separate ribs151,152,153of the set of ribs150are located closer to the central portion124bof the external sleeve surface124than the three separate ribs of each of the other two sets of ribs160,170.

The three separate ribs of each set of the three sets of ribs150,160,170are circumferentially spaced apart from each other by a distance to provide sufficient space between ends of adjacent ribs for air flow therethrough during operation of the air dryer governor assembly120. The locations of the three sets of ribs150,160,170relative to each other on the external sleeve surface124as well as the distances between adjacent ribs in each set of ribs provides a maximum strength of the plastic governor sleeve122using a minimum number of ribs while supporting sufficient air flow through the air dryer governor assembly120.

The plastic governor sleeve122preferably comprises a nylon material that is reinforced with glass fibers. As an example, the nylon material of the plastic governor sleeve122may comprise Nylon 6/6 with glass fiber of 43%. Other nylon materials with other percentages of glass fiber are possible. Glass fibers of each rib are oriented in a direction substantially parallel to the longitudinal central axis132of the governor piston130. The body portion123of the plastic governor sleeve122is reinforced with glass fibers oriented in one or more directions that are different from the direction in which glass fibers of each rib are oriented.

Referring toFIG.7, a schematic diagram showing orientation of glass fiber in an individual rib (e.g., the individual rib151shown inFIGS.4and5) relative to orientation of glass fibers in the body portion123of the plastic governor sleeve122is illustrated. More specifically,FIG.7includes one or more arrows “rib” indicating orientation of glass fibers in the individual rib151, one or more arrows “body” indicating orientation of glass fibers in the body portion123, and one or more arrows “piston” indicating opposite directions of movement of the governor piston130(FIG.2) along its longitudinal central axis132within the plastic governor sleeve122. The “rib” arrows are oriented in a direction substantially parallel to the longitudinal central axis132of the governor piston130, and the “body” arrows are oriented in one or more directions that are different from the direction in which the “rib” arrows are oriented.

In accordance with an aspect of the present disclosure, the geometry of the ribs of the three sets of ribs150,160,170reinforces the plastic governor sleeve122to withstand loads from pressure, humidity, air flow, and high temperatures without experiencing performance issues. Notably, the ribs of the three sets of ribs150,160,170cooperate together to maintain the geometry of the plastic governor sleeve122with minimal deformation when the governor piston130slides along the internal sleeve surface126between the preset cut-out and cut-in settings. This prevents a gap from forming between the plastic governor sleeve122and the governor piston130. By preventing a gap from being formed, air leakage between the plastic governor sleeve122and the governor piston130is avoided.

A number of advantages are provided by the disclosed plastic sleeve122ofFIG.3. One advantage is weight savings in using a plastic material instead of a metallic material. The reduction in weight results in a reduction in fuel consumption by the vehicle and thereby a reduction in carbon dioxide emission by the vehicle.

Another advantage is the comparable structural rigidity of the plastic sleeve122to a metallic sleeve. The comparable structural rigidity of the plastic sleeve122is due to its anisotropic properties (i.e., its different mechanical behavior in the x, y, and z directions). Moreover, the shape, dimensions, locations, and pattern (i.e., geometry) of the ribs on the external sleeve surface124, as well as the orientation of glass fibers in the ribs, augment the structural rigidity of the plastic sleeve122.

Although the above description describes the plastic governor sleeve122embodied in an air dryer apparatus100comprising the air dryer governor assembly120, it is conceivable that the plastic governor sleeve122be embodied in a different apparatus. For example, as shown inFIG.8, an apparatus900comprises an air dryer governor replacement kit910. The air dryer governor replacement kit910includes a governor & cover assembly920, and a combination of kit components including a number of O-rings930, a number of hardware pieces (e.g., screws and washers)940, and a tube of lubricant950. The governor & cover assembly920shown inFIG.8includes a plastic governor sleeve922that has the same structure and functionality as the plastic governor sleeve122shown inFIG.3.

While the present invention has been illustrated by the description of example processes and system components, and while the various processes and components have been described in detail, applicant does not intend to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will also readily appear to those skilled in the art. The invention in its broadest aspects is therefore not limited to the specific details, implementations, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.