Assembly for a tire inflation system

An assembly includes a rotary joint spindle and a rotary joint body rotatably disposed on and in fluid communication with the rotary joint spindle. The rotary joint body is housed by a hub cap and provided adjacent an end of a spindle. A pressure relief valve is disposed between the hub cap and the rotary joint body. The pressure relief valve selectively provides a seal between the hub cap and the rotary joint body.

BACKGROUND OF THE INVENTION

The invention relates to an assembly for a vehicle. More particularly, the invention relates to an assembly for use in vehicle tire inflation system.

Tire inflation systems for vehicles are used to provide a vehicle with the versatility to maneuver over differing terrain types and to reduce maintenance requirements. For example, one or more wheel assemblies in fluid communication with a tire inflation system may have a tire pressure which can be lowered to provide additional traction for the vehicle or raised to reduce the rolling resistance and increase the fuel efficiency of the vehicle. Additionally, utilizing the tire inflation system may eliminate the need to periodically check and adjust the tire pressure within each wheel assembly in communication with the system.

Tire inflation systems often employ a rotary joint to allow the rotating portions and non-rotating portions of the vehicle to communicate pressurized fluid effectively. Pressure can build adjacent the rotary joint because of temperature changes and/or churning of lubricant. It is preferable to vent the pressure without allowing the lubricant to escape. If the pressure is not vented or the lubricant escapes a failure in or near the tire inflation system can occur.

Thus, it would be desirable to provide an assembly that allows the rotating and non-rotating portions of the tire inflation system to communicate, allows pressure adjacent the assembly to be vented and prevents lubricant from escaping when the pressure is being vented.

BRIEF SUMMARY OF THE INVENTION

Embodiments of an assembly are provided.

In an embodiment, the assembly comprises a rotary joint spindle. A rotary joint body is rotatably disposed on and in fluid communication with the rotary joint spindle. The rotary joint body is housed by a hub cap and provided adjacent an end of a spindle. A pressure relief valve is disposed between the hub cap and the rotary joint body. The pressure relief valve selectively provides a seal between the hub cap and the rotary joint body.

In another embodiment, the assembly comprises a rotary joint spindle which is attached to a spindle and in fluid communication with a spindle air passage formed in the spindle. A rotary joint body is provided adjacent an end of the spindle and rotatably disposed on and in fluid communication with the rotary joint spindle. A rotary seal assembly seals against an inner surface of the rotary joint body and is disposed around a second outer diameter portion of the rotary joint spindle. A pressure relief valve is separated from the rotary seal assembly by the rotary joint body and disposed between a hub cap and the rotary joint body. The pressure relief valve selectively provides a seal between the hub cap and the rotary joint body. A bolt is concentric with the pressure relief valve and in fluid communication with the rotary joint spindle via a chamber formed in the rotary joint body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of an assembly10are described herein. The assembly10will be described in connection for use with a tire pressure management system or tire inflation system. Preferably, the tire inflation system is a central tire inflation system. Central tire inflation systems are known and are utilized in inflating, deflating and maintaining the tire pressure of one or more wheel assemblies (not depicted) attached to a vehicle (not depicted).

It would be understood by one of ordinary skill in the art that the various embodiments of the assembly10described herein may have applications to commercial and off-highway vehicles. Furthermore, it would be understood by one of ordinary skill in the art that the aforementioned embodiments could have industrial, locomotive, military and aerospace applications.

Embodiments of the assembly10are preferably used with a steer axle assembly. A portion of an embodiment of a steer axle assembly suitable for use with the assembly10is shown best inFIG. 1. However, it should be appreciated that the assembly and/or certain portions thereof may be used apart from a steer axle assembly. For example, in certain embodiments (not depicted), the assembly and/or certain portions thereof may be used with both driven and undriven non-steering axle assemblies.

Referring now toFIGS. 1 and 2, the steer axle assembly comprises a steer axle (not depicted) having an outboard end. The outboard end has a king pin bore extending therethrough. A knuckle12is located adjacent the outboard end of the steer axle. The knuckle12has an upper portion14and lower portion16. The upper portion14defines an upper king pin boss18and the lower portion16defines a lower king pin boss (not depicted). The bosses are generally vertically aligned with one another. An upper bore22extends through the upper king pin boss18and a lower bore extends through the lower king pin boss. The boss bores are aligned with the king pin bore.

The upper bore22, the lower bore and the king pin bore receive a king pin (not shown) therethrough. Bearings maybe located within the bores to pivotally support the king pin therein. The king pin pivotally connects the knuckle12with the steer axle.

A spindle26is attached to the knuckle12. The spindle26is a cone-shaped structure extending from the knuckle12in an outboard direction. In the depicted embodiment, the spindle26tapers downwardly from an inboard side28adjacent the king pin to an outboard side30. One or more steer arms or other suspension component connections portions may also be attached or connected to the knuckle12.

A knuckle air passage32extends through the knuckle12. InFIG. 1, the knuckle air passage32begins adjacent the upper king pin boss18. The passage32extends toward the spindle26at a downward angle. While one passage through the spindle26is depicted, it can be appreciated that other passages at different angles or locations can be located in the spindle26. The number of passages can also vary.

The knuckle air passage32intersects and is in fluid communication with a spindle air passage34. Preferably, the knuckle air passage32intersects the spindle air passage34adjacent a first end36thereof. In the embodiments illustrated, the knuckle air passage32is provided in a substantially perpendicular relationship with the spindle air passage34.

The spindle air passage34extends in an outboard direction through the spindle26. As shown best inFIG. 2, the spindle air passage34extends along a longitudinal axis of the spindle26. The spindle air passage34may be of a diameter which is substantially constant.

A hub38is rotatably mounted on and concentric with the spindle26. Bearings40are located between the hub38and spindle26to permit the hub38to rotate with respect to the spindle26. The hub38has a fastener flange42. Fasteners44are located through the fastener flange42for connecting the hub38to a wheel assembly (not depicted). The hub38may also have a braking surface45attached thereto. As illustrated best inFIGS. 1 and 2, the braking surface is provided as a portion of a brake rotor47. The brake rotor47is attached to the hub38and located on the hub38inboard of the fasteners44.

Referring now toFIGS. 2 and 3, a rotary joint spindle46is attached to the spindle26. Adjacent a second end49of spindle air passage34, an inboard portion48of the rotary joint spindle46is located within the spindle air passage34. More particularly, the inboard portion48is located in the spindle air passage34at an outboard end portion50of the spindle26.

The rotary joint spindle46has an air passage52which is continuous and extends from the inboard portion48to an outboard portion54. The passage52is air tight and in fluid communication with and longitudinally aligned with the spindle air passage34. In an embodiment, the passage52is of a substantially constant diameter in the inboard portion48and increases in diameter in the outboard portion54.

The inboard portion48comprises a first outer diameter portion56and the outboard portion54comprises a second outer diameter portion58. The second outer diameter portion58is of a diameter which is greater than that of the first outer diameter portion56.

A rotary seal assembly60is located on an inboard portion62of the second outer diameter portion58. The rotary seal assembly60prevents, or reduces, air leakage into an area between the spindle26and the hub38. The rotary seal assembly60comprises an inner diameter surface64, an outer diameter surface66and a groove68between the two surfaces64,66. The rotary seal assembly60is disposed around the second outer diameter portion58of the rotary joint spindle46such that the inner diameter surface64is in direct contact with the second outer diameter portion58.

The groove68faces an outboard direction. A biasing member (not depicted) may be located within the groove68. In certain embodiments, the biasing member is a spring. In these embodiments, the spring is a circular spring such as a garter spring. In other embodiments, the biasing member is a V-shaped serrated ring. The ring is preferably flexible and metallic. The biasing member biases the rotary seal assembly60into engagement with the second outer diameter portion58so that the rotary seal assembly60seals against the rotary joint spindle46.

A rotary joint body70is provided adjacent an end72of the spindle26and rotatably disposed on the rotary joint spindle46via a bearing74. The rotary joint body70is a hollow body and the rotary joint spindle46extends into an interior of the rotary joint body70. The outboard portion54of the rotary joint spindle46is located adjacent a radially inward extending flange78of the rotary joint body70. Preferably, the rotary joint spindle46and the rotary joint body70are not in direct contact with one another and are separated from one another by a gap80.

The rotary joint spindle46and the rotary joint body70are in fluid communication. As stated above, the rotary seal assembly60seals against the rotary joint spindle46. The rotary seal assembly60also seals against the rotary joint body70. More particularly, the rotary seal assembly60seals against an inner surface82of the rotary joint body70. The rotary seal assembly60prevents, or reduces, air from leaking from a chamber84formed in the rotary joint body70positioned between the rotary joint spindle26and a bolt86.

The rotary joint body70is at least partially concentric with and partially houses the rotary joint spindle46. The rotary joint body70also houses the rotary seal assembly60and the bearing74. The bearing74is located between the inner surface82of the rotary joint body and the first outer diameter portion56of the rotary joint spindle46to permit the rotary joint body70to rotate with respect to the rotary joint spindle46. The bearing74has an outer race88in direct contact with the inner surface82of the rotary joint body70and an inner race90in direct contact with the first outer diameter portion56of the rotary joint spindle46. The rotary joint body70may have a crimped portion92provided over the outer race88to retain it in place.

The inner race90abuts, on one side, the second outer diameter portion58of the rotary joint spindle46. The other side of the inner race90abuts against a spacer94. The spacer94separates the bearing74from the end72of the spindle26and is disposed around the rotary joint spindle46. More particularly, the spacer94has an inboard portion96and an outboard portion98. The inboard portion96is located adjacent to the outer race88on one side and the end72of the spindle26on the other side. The outboard portion98directly abuts the inner race90.

The inner surface82of the rotary joint body70generally decreases in diameter in an outboard direction. The chamber84is provided in a reduced diameter portion100of the inner surface82. The chamber84has a substantially constant diameter and is in fluid communication with the rotary joint spindle46on an end102and an open end104of the bolt86on an opposite end106.

The rotary joint body has an outer surface108. The outer surface108adjacent an outboard end portion110of the rotary joint body70is multi-faceted. Preferably, adjacent the outboard end portion110, the outer surface108has a portion112which is of a hexagonal shape or nut shape. From the hexagonally-shaped portion112, the outer surface108has a substantially constant diameter in an inboard direction toward the knuckle12until it gradually increases in diameter adjacent an inner rib114and an internal rib116of a hub cap118.

The bolt86is fluid communication with the rotary joint spindle46via the rotary joint body70. Preferably, the bolt86is of the banjo variety. The bolt86has an opening120adjacent the chamber84and a hollow body122. The hollow body122comprises the inboard open end104and an outboard end126. The hollow body122permits air to flow from the rotary joint spindle46and rotary joint body70through the bolt86. The bolt86is at least partially disposed within the rotary joint body70and is concentric with a pressure relief valve128,128A. More particularly, the open end104is located within the rotary joint body70. The rotary joint body70is concentric with the open end104.

An aperture130is provided adjacent the outboard end126of the body122. The aperture130allows the bolt86to communicate with a ring132. The ring132has a nib134projecting from its exterior. Preferably, a hose136is attached to an outer surface of the nib134to allow fluid communication with ring132. The hose136is in fluid communication with the bolt86via the ring132. Preferably, the hose136is also in fluid communication with the wheel assembly. The hose136may be in fluid communication with the wheel assembly through other connections, joints and/or valves as required. When inflating, deflating or maintaining the tire pressure of the wheel assembly, a pressurized fluid such as, for example, air is directed through the knuckle air passage32, spindle air passage34, passage52in the rotary joint spindle46, rotary joint body70, bolt86and ring132to the hose136or vice versa.

The bolt86and at least a portion of the rotary joint body70are at least partially housed within an external rib138of the hub cap118. The external rib138extends almost entirely circumferentially about the bolt86and a portion of the rotary joint body70. A gap is provided in the external rib138to accommodate the hose136extending from the nib134. The external rib138protects the bolt86, ring132, nib134, and the connection of the hose136at the nib134from damage.

The hub cap118is attached to the hub38. More particularly, a hub cap wall portion142is attached to the hub38. The hub cap118extends radially and in a generally outboard direction from the hub38. Both the hub cap118and hub38are constructed of a robust material such as, for example, steel.

The rotary joint body70is housed by the hub cap118. The hub cap118also houses the rotary joint spindle46and at least a portion of the spindle26. The hub cap118comprises the inner rib114, internal rib116and external rib138. In an embodiment, the inner rib114, internal rib116and external rib138are formed in a unitary manner. In another embodiment, one or more of the inner rib114, internal rib116and external rib138are formed as separate members. The inner rib114, internal rib116and external rib138each house a portion of the rotary joint body70. Preferably, at least a portion of the rotary joint body70is concentric with the inner rib114, internal rib116and external rib138. The hub cap118extends in a radial direction via the inner rib114, in an inboard direction via the internal rib116and in an outboard direction via the external rib138.

The internal rib116extends in a substantially opposite direction from the external rib138. The figures depict the internal rib axially opposite the external rib, however, the ribs need not be so oriented. As shown best inFIG. 4, the internal rib116is annular and housed by a hub cap wall portion142. A plurality of grooves144are formed in an inner surface146of the internal rib116. In the depicted embodiments, the grooves144are the same size, shape and have the same depth. The grooves144are generally rectangular-shaped and preferably circumferentially and equally spaced apart. Preferably, each groove144extends axially across the inner surface146of the internal rib116to the inner rib114. The grooves144are also oriented all in the same direction, namely, parallel to an axis of the body.

The inner rib114is attached to the internal rib116and external rib138and separates the ribs116,138from each other. As noted above, the inner rib114extends in a radial direction and houses a portion of the rotary joint body70. The inner rib114also houses a portion of the bolt86. The inner rib114is an annular portion and defines a hole148. It can be appreciated based on the foregoing components and design, that no torque is being transferred through the hose148. Instead, any torque that is present is transferred through the connection of the rotary joint body70to the hub cap118via the hole148defined by the inner rib114. Preferably, the hole148has a hexagonal shape. When the outer surface108of the rotary joint body70has a hexagonal shape, the outer surface108fits within the complimentary shaped hole148.

The hub cap wall portion142is an annular portion and may be formed in a unitary manner with one or more of the ribs114,116,138. Alternatively, the hub cap wall portion142may be formed as a separate member. Referring back toFIG. 3, the hub cap118houses a baffle150. More particularly, the hub cap wall portion142houses the baffle150. The baffle150is attached to the rotary joint body70. The internal rib114is partially disposed between the baffle150and the outer surface108of the rotary joint body70.

The baffle150may have a general L-shaped cross-section. The baffle150comprises a first leg152which is located adjacent and parallel to the internal rib116. The baffle150also comprises a second leg154which may be located in a perpendicular relationship with the internal rib116and the outer surface108of the rotary joint body70. It can be appreciated from the foregoing that in order to accommodate the internal rib116and the rotary joint body70, the baffle150is a generally annular member with a hollow interior defined by the first leg152and second leg154.

The pressure relief valve128,128A is disposed between the hub cap118and the rotary joint body70. More particularly, the pressure relief valve128,128A is located in a cavity156formed between the inner rib114, internal rib116and the rotary joint body70. The pressure relief valve128,128A is separated from the rotary seal assembly60by the rotary joint body70. However, it should be appreciated that the pressure relief valve128,128A may be utilized adjacent other portions of the tire inflation system or apart from the tire inflation system. The pressure relief valve128,128A selectively provides a seal between the hub cap118and the rotary joint body70. More particularly, the pressure relief valve128,128A selectively provides a seal on an inboard surface157of the inner rib114and provides a seal on the outer surface108of the rotary joint body70. By selectively providing a seal between the hub cap118and the rotary joint body70, the pressure relief valve128,128A permits pressurized gas to escape from the hub38, helps to prevent lubricant from escaping the hub38and prevents dirt and debris from entering the hub38.

The pressure relief valve128,128A may be elastomeric and formed of a flexible material such as, for example, a polymer or rubber compound. In one embodiment, the pressure relief valve128,128A may be comprised of a 50 durometer rubber compound. While one rubber compound of a 50 durometer hardness has been disclosed, it can be appreciated that other materials with other hardness values may also be used.

The pressure relief valve128,128A is generally an annular member having a through hole158so that the pressure relief valve128,128A can be disposed around the outer surface108of the rotary joint body70. More particularly, a first end portion160of the pressure relief valve128,128A sealingly contacts the hub cap118and a second end portion162of the pressure relief valve128,128A abuts the outer surface108of the rotary joint body70. The through hole158has a first opening164adjacent the first end portion160and a second opening166adjacent the second opening166The through hole158extends between the first opening164and the second opening166. The first opening164preferably has a substantially constant diameter and is defined by the first end portion160. Also, the second opening166preferably has a constant diameter. In an embodiment like the one illustrated inFIGS. 5 and 6, the second opening166is defined by the second end portion162. In this embodiment, the diameter of the second opening166is larger than the diameter of the first opening164.

Referring now toFIG. 5, the pressure relief valve128also comprises an outer surface168and an inner surface170. The two surfaces168,170are bounded by a first end174and a second end176. The outer surface168and inner surface170extend in a continuous curvilinear fashion from the second end portion162to the first end portion160. The two surfaces168,170define between them a valve thickness. The valve thickness is greatest at the second end portion162and generally tapers down to the first end portion160where the valve thickness is the thinnest.

In an embodiment like the one shown inFIGS. 5 and 6, the inner surface170from the first opening164to the second opening166is a continuous, smooth surface. From the first opening164to the second opening166, the inner surface170increases in diameter in a smooth, continuous curvilinear fashion. In another embodiment like the one shown inFIGS. 7 and 8, the inner surface170increases in diameter in a smooth, continuous curvilinear fashion to a rib portion172.

In the embodiment illustrated inFIGS. 7 and 8, the rib portion172defines the second opening166and a portion of the through hole158. In this embodiment, the inner surface170generally decreases in diameter in an outboard direction from the second opening166to an end173of the rib portion172. From the end173of the rib portion172, the through hole158increases in diameter to the second end portion162. The inner surface170decreases in diameter adjacent the first end portion160from the second end portion162.

The rib portion172is attached to the second end portion162, decreases in thickness and extends radially and axially. The rib portion172comprises a portion175which extends radially toward the rotary joint body70from the second end portion162and a portion177which gradually decreases in thickness to the end173and extends axially in an outboard direction. As illustrated best inFIG. 3, the rib portion172is disposed on the outer surface108of the rotary joint body70and provides a seal thereon.

Referring back toFIG. 5, from the first end174to the second end176, the outer surface168increases in diameter in a general curvilinear fashion. A plurality of grooves178are formed in the outer surface168. More particularly, the grooves178are formed in the second end portion162and do change the thickness of the second end portion162in selective locations. The grooves178are separated from the rib portion172by the second end portion162. Preferably, the grooves178are integrally formed and unitary with the valve body and are circumferentially and equally spaced apart about the second end portion162. In the depicted embodiments, the grooves178are the same size, shape and have the same depth. The grooves178are also oriented in the same direction as each other and as the grooves144formed in the internal rib116of hub cap118.

Each groove178comprises a depth which is greatest adjacent the second end176. The depth of the grooves178gradually decreases from the second end176. Between approximately one third to one half of the way from the second opening166to the first opening164, the grooves178transition to the outer surface168which then extends from the grooves178to the first opening164. The grooves178make their transition without interruption.

The curvilinear shape of the outer surface168and inner surface170and the taper from the second end portion162to the first end portion160plays a role in allowing the seal to be selectively provided between the hub cap118and the rotary joint body70. More particularly, the curvilinear shape and the taper reduces contact pressure between the first end portion160of the pressure relief valve128,128A and the hub cap118. The reduction in contact pressure is in part due to the pressure relief valve128,128A being more flexible adjacent the first end portion160because it is thinner there and because the first end portion160only has a small surface area in contact with the hub cap118.

As noted above, the pressure relief valve128,128A permits pressurized gas to escape from the hub38. In operation, pressurized gas within the hub38is received against the second end portion162of the pressure relief valve128,128A and inner surface146of the internal rib116of the hub cap118. Pressurized gas may equally flow through the grooves144formed in the hub cap118and the grooves178formed in the pressure relief valve128,128A or it may flow through one or more grooves144,178in unequal amounts or at different times. After flowing through the grooves144,178, the pressurized gas follows the outer surface168of the pressure relief valve128,128A toward the first end portion160. At a predetermined pressure, the first end portion160is biased away from the hub cap118and flexes radially inward toward the rotary joint body70. The bias may be at one or more discrete points at the first end portion160or substantially circumferentially about the first end portion160of the pressure relief valve128,128A. Pressurized gas is then permitted to escape past the first end portion160and the hub cap118. Thus, the assembly10allows pressurized gas adjacent the assembly to be vented.

After venting some or all of the pressurized gas, the first end portion160then returns back to its original shape and orientation and the seal provided between the hub cap118and the rotary joint body70is restored. Preferably, the seal is restored before allowing lubricant contained in the hub38to escape. Therefore, the pressure relief valve128,128A also helps to prevent lubricant from escaping the hub38.

The location of the pressure relief valve128,128A within a serpentine path184also helps to prevent lubricant within the hub38from escaping. The serpentine path184is provided in the assembly10to permit pressurized gas to escape as described above and also to restrict, or prevent, lubricant from escaping from the hub38. Also, the serpentine path184helps to prevent dirt and debris from entering into the hub38. The serpentine path184is described in detail below with reference toFIG. 3.

From within the hub38, the serpentine path184begins in a space180between the hub cap118and baffle150. Next, the serpentine path184extends to a gap between the end of the first leg152of the baffle150and the hub cap118. The serpentine path184further extends between the first leg152of the baffle150and an outer surface182of the internal rib116. The serpentine path184also extends around the end of the first leg152of the baffle150. The serpentine path184continues between the inner surface146of the internal rib116and the rotary joint body70until it encounters the pressure relief valve128,128A as described above. The serpentine path184extends from the pressure relief valve128,128A to between the hole148formed in the inner rib114of the hub cap118and the outer surface108of the rotary joint body70. Once the air passes through the rotary joint body70and the hole148it passes the external rib138of the hub cap118as it is released to the atmosphere.

The shape, taper and position of the pressure relief valve128,128A also function to resist external contaminants such as, for example, moisture and/or debris from entering the hub38. More particularly, contaminants which attempt to enter the hub38are received against the inner surface170of the pressure relief valve128,128A. Contaminants received against the pressure relief valve128,128A push against the first end portion160, which is directed radially inwardly, and biases the end portion160against the hub cap118. When the first end portion160is being biased against the hub cap118, the seal is maintained which prevents contaminants from entering the hub38via the hub cap118.