Method and apparatus for detecting worn universal joint components

A method and apparatus for detecting the operating condition of a universal joint in a driveline assembly utilizes a pressure relief valve that is supported by a universal joint cross member. The cross member includes a central body portion with a plurality of radially extending trunnions. A first driveline component supports a first yoke member and a second driveline component supports a second yoke member. Each yoke member cooperates with two opposing trunnions to interconnect the first and second driveline components. An internal lubrication channel is formed within the cross member and is in fluid communication with each trunnion. Seal assemblies are installed within cups mounted to each trunnion member to seal the lubricating fluid within the cross member. The universal joint is operating properly when lubricating fluid that is injected through an external lubrication fitting during service operations, exits via the pressure relief valve. The universal joint is not operating properly when the lubricating fluid exits via at least one of the seal assemblies instead of through the pressure relief valve.

BACKGROUND OF THE INVENTION

This invention generally relates to a method and apparatus for servicing a universal joint assembly installed in a vehicle driveline to detect worn components.

Vehicle drivelines include at least one driveshaft that is used to transmit power from a vehicle engine and transmission to a single drive axle or tandem drive axle. Typically, heavy-duty vehicles, such as large trucks, include more than one driveshaft due to the long wheelbase and/or use of a tandem drive axle. At each end of a driveshaft, universal joints (U-joints) are used to connect the driveshaft to the next driveline component. For example, U-joints can be used to connect one driveshaft to another driveshaft or can be used to connect a driveshaft to a drive axle component.

U-joints allow two driveline components to be positioned at different angles relative to each other to accommodate relative movement and angular misalignment. Further, as the drive axles cooperate with a vehicle suspension to dampen shocks from rough road conditions, the U-joints provide flexibility to allow the adjoining driveline components to move relative to one another.

Typically, U-joints include two yokes that each have two bore locations at diametrically opposed positions. The yokes are each mounted to two trunnions on a center cross member. The combination allows the two yokes to move angularly relative to each other with respect to the center of the cross member.

In order for the U-joint to operate properly overlong periods of time, it is important to have good lubrication. The center cross member typically includes an external grease fitting that is in fluid communication with each of the trunnion members via internal grease grooves or channels. Bearing packs are mounted on each of the trunnions and receive lubrication through the grease grooves. The bearing packs include a seal assembly that seals the grease within the center cross member.

It is often difficult to detect when U-joint components have worn sufficiently, such that repair or replacement operations are required. Currently, to detect worn seals, the U-joint must be completely disassembled and inspected. This process is time consuming and labor intensive, which results in increased service costs and vehicle downtime, both of which are undesirable.

Thus, it would be valuable to have a simple and efficient inspection procedure to detect worn U-joint components without having to disassemble the U-joint. The method and apparatus to detect worn components should be easily incorporated into existing U-joints without significant increases in cost.

SUMMARY OF THE INVENTION

A serviceable, permanently lubed, universal joint assembly utilizes a fluid pressure member to detect the operating condition of a universal joint assembly during a service operation. The universal joint assembly includes a cross member having a plurality of trunnions that cooperate with yoke members supported by adjacent driveline components. Each trunnion supports a seal and bearing assembly which are mounted within a cap installed over a distal end portion of the trunnion.

The operating condition of the internal components, such as bearings and seals, can be easily detected without having to disassemble the universal joint assembly. A lubricating fluid is injected into the cross member via an external lubrication fitting. A properly operating universal joint assembly is detected when lubricating fluid exits the fluid pressure member, and an improperly operating universal joint assembly is detected when the lubricating fluid exits at least one of the seal assemblies instead of the fluid pressure member.

In the preferred embodiment, the cross member includes a central body portion with a first pair of trunnions coupled to a first yoke member and a second pair of trunnions coupled to a second yoke member. The cross member includes an internal lubrication channel that is in fluid communication with each of the trunnions. An external lubrication fining is supported by the cross member and is in fluid communication with the internal lubrication channel. The fluid pressure member is supported by the cross member and also is in fluid communication with the internal lubrication channel. An internal fluid pressure is generated within the cross member in response to a lubricating fluid being injected into the internal lubrication channel via the external lubrication fitting. A first operating condition is indicated when the internal fluid pressure is below a predetermined pressure value and a second operating condition, different than the first operating condition, is indicated when the internal fluid pressure exceeds the predetermined pressure value.

As discussed above, each of the trunnions includes a seal assembly that seals the lubricating fluid within the internal lubrication channel. Each seal assembly has a predetermined initial sealing force that is greater than the predetermined pressure value. The first operating condition is defined as the improperly operating universal joint and occurs when at least one of the seal assemblies has an operating sealing force that is less than the predetermined initial sealing force and less than the predetermined pressure value, such that the lubricating fluid exits the cross member through the defective seal assembly instead of through the fluid pressure member. The second operating condition is defined as the properly operating universal joint and occurs when the internal fluid pressure achieves the predetermined pressure value, which activates the fluid pressure member and allows lubricating fluid to exit the cross member via the fluid pressure member.

In one disclosed embodiment, the fluid pressure member comprises a pressure relief valve mounted directly to the cross member. The pressure relief valve is resiliently biased such that lubricating fluid cannot exit the cross member until the predetermined pressure value is achieved. The pressure relief valve is preferably threaded to the central body portion and is centrally positioned on an end face of the central body portion or on an edge between adjacent trunnions.

Thus, the subject invention provides a method and apparatus for easily detecting worn components in a universal joint assembly without requiring the universal joint assembly to be disassembled. These and other features of the present invention can be best understood from the following specifications and drawings, the following of which is a brief description.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A heavy-duty vehicle10includes a powertrain assembly, shown generally at12, that transfers driving power from an engine14to a plurality of wheels16. The engine14is operably coupled to a transmission18as is known in the art. A driveline assembly20, including at least one driveshaft22, is used to transfer driving power from the transmission18to a drive axle assembly24that supports the wheels16. The drive axle assembly24can be a single drive axle (not shown) or can be a tandem drive axle as shown in FIG.1. The tandem drive axle includes a forward-rear axle24aand a rear—rear axle24bthat are interconnected to each other.

Preferably, due to the long wheelbase required for heavy-duty vehicles10and/or due to the use of a tandem drive axle, a plurality of driveshafts22are used to connect the transmission18to the drive axle assembly24. It should be understood however, that while multiple driveshafts22are preferred, a single driveshaft22could be used to connect the transmission18to a single drive axle for lighter duty applications.

FIG. 2shows a typical driveshaft arrangement that includes a first driveshaft22aconnected to the transmission18at one end and connected to a second driveshaft22bat an opposite end. The second driveshaft22bis connected to the drive axle assembly24at an end opposite from connection to the first driveshaft22a. A third driveshaft22cis used to interconnect the forward-rear axle24ato the rear—rear axle24b. A yoke member26is supported on each end of the driveshafts22a,22b,22c. A cross member28is used to interconnect adjoining yoke members26. One cross member28, coupled to two (2) yoke members26, defines a universal joint assembly (U-joint)30.

U-joints allow two adjoining driveline components to be positioned at different angles relative to each other to accommodate relative movement and angular misalignment. Misalignment and relative movement can be caused by adjoining driveline components not being mounted within a common plane, or can be caused by a driveline component, such as a drive axle assembly24, moving relative to adjoining driveline component, such as a driveshaft22, in response to interaction with a vehicle suspension.

The cross member28is shown in greater detail in FIG.3. The cross member28includes a central body portion32with a plurality of trunnions34extending out radially from the central body portion32. Each yoke member26is attached to a pair of trunnions34, as is known in the art.

Bearing packs or needle cups36are installed over each trunnion34. The needle cups36include a mounting interface38that attaches to the yoke member26. The cross member28shown inFIG. 3has one exposed trunnion34and three trunnions with installed needle cups36. The central body portion32also includes at least one external lubrication fitting40through which a lubricating fluid, such as grease, is injected into the cross member28to provide lubrication so that the U-joint30can operate properly.

Each needle cup36includes an internal cavity42that is slidably received over one trunnion34. A plurality of needle bearings44is mounted within the cavity42. A thrust washer46is preferably mounted within the bottom of the cavity42and a seal assembly48surrounds a lip of the cavity42to seal the lubricating fluid within the cross member28.

The cross member28includes an internal lubrication channel50, shown inFIG. 5, which is in fluid communication with the external lubrication fitting40. The internal lubrication channel50includes a central portion50a, trunnion portions50bthat extend into each trunnion34, and a fitting portion50cthat communicates with the lubrication fitting40. This allows lubricating fluid, which is injected through the lubrication fitting40, to be communicated through internal lubrication channel50to each trunnion34, so that the needle bearings44can be sufficiently lubricated.

A fluid pressure member52is supported by the central body portion32and is positioned to be in fluid communication with the internal lubrication channel50. The fluid pressure member52is utilized during service operations to detect U-joints30that have worn internal components, such as bearings44and seal assemblies48, without having to disassemble the U-joint30.

Each of the seal assemblies48has a predetermined initial sealing force when the U-joint30is first assembled. Over time, as components wear and as the vehicle10experiences heavy operating loads and adverse road conditions, the initial sealing force is reduced. During service, lubricating fluid is injected with a grease gun or other similar mechanism, into the cross member28via the lubrication fitting40. This generates an internal fluid pressure within the cross member28. If the seal assemblies are still in good working condition, the internal lubrication channel50will fill with fluid until fluid is forced to exit via the fluid pressure member52. Thus, the fluid pressure member52is responsive to or activated when a predetermined pressure value is achieved within the cross member28. This predetermined pressure value is less than the initial sealing force for the seal assemblies48.

If the seal assemblies48are worn and need to be replaced, as the internal fluid pressure increases, fluid will exit the cross member28via the defective seal assembly48, instead of through the fluid pressure member52. In other words, fluid will exit the cross member28from a defective seal assembly48because the worn seal has a reduced sealing force is less than the predetermined pressure value that activates the fluid pressure member52. Thus, when fluid exits the cross member from the fluid pressure member52, the U-joint30internal components are still in good operating condition, and when the fluid exits from at least one of the seal assemblies48, a worn internal component is detected. Thus, a simple external visual inspection can be used to detect internal worn components.

In one embodiment, the fluid pressure member52is located at an edge54of the central body portion32of the cross member28, as shown in FIG.5. The fluid pressure member52in this embodiment, is positioned between adjacent trunnions34and extends out radially from the central body portion32. The internal lubrication channel50is formed with a channel portion50dthat extends to the fluid pressure member52.

In another embodiment, the fluid pressure member52is located centrally on the central body portion32, as shown inFIGS. 3 and 6. The internal lubrication channel50includes a similar channel portion50dthat communicates with the fluid pressure member. It should be understood that the fluid pressure member52could be mounted in other positions or locations on the central body portion32. Similarly, the external lubrication fitting40could also be mounted at other locations on the central body portion.

Preferably, the fluid pressure member52is a pressure relief valve60that is movable between a sealed or closed position, shown inFIG. 7, and an unsealed or open position, shown in FIG.8. The pressure relief valve60includes a longitudinal valve body62mounted within a bore80that extends from an internal end64to an external end66. The internal end64of the bore80is in fluid communication with the internal lubrication channel50and the external end of the bore80is selectively opened to the external atmosphere when the predetermined pressure value is achieved within the cross member28.

The pressure relief valve60preferably includes a threaded external surface68that is threaded into a threaded bore70formed within the cross member28. A resilient member72, such as a coil spring or other similar mechanism, cooperates with a movable cap74formed on the valve body62. The movable cap74is resiliently biased to seal the external end66of the bore80under normal operating conditions. During a service operation, when lubricating fluid is injected into the cross member28and the internal fluid pressure is greater than the predetermined pressure value, the resilient bias force is overcome and the movable cap74opens. This allows fluid communication to the external surface of the cross member28via the external end66of the bore80. Once the internal pressure is reduced, the resilient member72returns the movable cap to the initial position.

The subject invention provides a method and apparatus for easily detecting worn components in a universal joint assembly that does not require disassembly. An additional benefit is that a simple external visual inspection can be used to detect internal worn components in the U-joint. Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.