Patent Application
20050087930
The present invention relates to press fit components, and more particularly to a bore geometry to receive a press fit seal assembly and a method of installation thereof.
Various housings include a bore to receive a press fit member such as a seal. The seal provides a rotational interface between the housing and a rotating shaft such as common to a differential carrier assembly for an axle assembly. Proper installation of press fit components may often be a relatively complex procedure which requires high press forces and tight tolerances.
A press fit seal utilizes an interference fit between the seal outer diameter and a housing bore diameter. The seal outer diameter is typically press fit into the bore diameter with a tool to provide alignment of the seal with the bore. Even a slight misalignment of the seal to the bore may result in an unacceptable misalignment. Some seals have a rubber outer diameter which may be even more easily damaged from an initial misalignment.
Relatively complex and expensive tooling is utilized to press fit the seal into the bore which is often chamfered in an attempt to initiate the seating of the seal. Even though the tooling indexes in a number of locations on the housing and the seal, misalignment may still occur due to the strict tolerance requirements. Minor misalignment is overcome by the force of the press which may yield the seal outside diameter such that the seal is press fit in a cocked or offset orientation. Such minor misalignment difficult to detect through conventional quality control procedures. However, even a relatively small misalignment may result in a failed seal. Furthermore, the minor misalignment may still go unnoticed and be misdiagnosed as a shaft to bore misalignment problem resulting in costly overhaul, repair and/or replacement of relatively expensive components.
In addition to assuring proper alignment, press fit seal components must also provide a fluid tight barrier. Even when properly aligned, conventional seals often require a resilient gasket material coating to seal the seal outer diameter into the housing. Such a resilient material is often incompatible with press fitting as the resilient gasket material may be stripped from the seal outer diameter during the press fitting operations. A properly aligned seal may therefore still be subject to leakage.
Eventually, even if initially properly installed and sealed, the press fit component may need to be replaced in a field environment. Such replacement is quite difficult to achieve in a field environment in which relatively large and complex tooling available in a manufacturing setting is unavailable.
Accordingly, it is desirable to provide a bore geometry to receive a press fit component and a method of installation thereof which assures alignment of the press fit component without damaging a resilient gasket material coating. It is further desirable to provide a press fit component which may be replaced in a relatively austere field environment.
The bore geometry of a housing according to the present invention provides a bore diameter for the interference fit of a press fit component such as a seal assembly. A locating bore is located adjacent the bore and extends for an axial length to provide an index on the seal outer diameter. The locating bore is of a diameter which provides a tightly held clearance fit for receipt of the seal outer diameter. That is, the seal assembly is received into the locating bore such that the seal assembly rests upon a chamfer between the locating bore and the bore.
A gasket material is located about the seal outer diameter. By providing a locating bore which closely fits the seal outer diameter the locating bore provides a reception area for the gasket material once the seal assembly is press fit into the bore. An effective oil seal is therefore provided between the seal outer diameter and the bore by the present invention.
In a method of assembly according to the present invention, the seal assembly is initially placed into the locating bore such that the seal rests against a chamfer between the locating bore and the press fit bore. The seal assembly is thereby aligned with the press fit bore by the placement of the seal assembly into the locating bore. Complex alignment and indexing tooling is therefore effectively eliminated.
A flat surface such as a mandrel which extends from a press is then utilized to press the seal assembly into the bore. As the locating bore provides alignment, only a relatively simple press with minimum indexing is required.
The present invention therefore provides a bore geometry to receive a press fit component and a method of installation thereof which assures alignment of the press fit component and the formation of a gasket material. The present invention further provides a press fit component which may be replaced in a relatively austere field environment.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:
Referring to
Referring to
A chamfer 30, 32 are preferably located along the top of the locating bore 28 and between the locating bore 28 and the bore 20. A chamfer 33 is also preferably located on the insert edge of the seal assembly 18. The chamfers 30, 32, 33 assist in locating and driving the seal assembly 18 into the bore 20. It should be understood that the term “chamfer” as used herein includes radiuses and any broken edge.
The locating bore 28 is of a diameter which provides a clearance fit for receipt of the seal outer diameter 24. That is, the seal assembly 18 is received into the locating bore 28 such that the seal assembly 18 rests upon the chamfer 32 between the locating bore 28 and the press fit bore 20 (
A gasket material 34 is located about the seal outer diameter 24. Preferably, a flow on gasket material or other liquid gasket material such as LOCTITE 518® is beaded along the seal outer diameter 24. The gasket material 34′ may alternatively or additionally be located about the locating bore 28 (
By providing a locating bore 28 which closely fits the seal outer diameter 24 the locating bore 28 provides a reception area R for the gasket material 34 once the seal assembly 18 is press fit into the press fit bore 20 (
Referring to
That is, the seal assembly 18 is simply dropped into place by hand. The seal assembly 18 rests upon the chamfer 32 between the locating bore 28 and the press fit bore 20 prepositioned for a pressing operation (
A flat surface 36 such as a mandrel which extends from a press (illustrated schematically at 38) is then utilized to press the seal assembly 18 into the press fit bore 20. As the locating bore 28 provides alignment, only a relatively simple press is required. A radial flange 38 provides depth control of the pressing operation.
Moreover, the axial length of the locating bore 28 tends to index the seal assembly 18 perpendicular to the press fit bore 20 even if the seal assembly 18 is initially not exactly perpendicular thereto. That is, the locating bore tends to correct misalignment when the seal assembly 18 is pressed by the flat surface 36 in comparison to a conventional tool which tends to press the seal crooked if the seal is initially misaligned.
Referring to
The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention maybe practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.
