Direct drum bushing

An improved bushing restricts exhaust at a lube transfer port and exhaust ports equalizing bushing lube PSI with lube supply PSI. A hole or pair of holes in the bushing with an area equal to that of the lube supply holes in a center support regulates an intermediate pressure to the bushings of 50% of the supply pressure on its own, regardless of the balance piston. When the balance piston is filled, the added resistance at the transfer orifices will begin to equalize bushing lube PSI with lube supply PSI. When the balance piston exhaust ports are also restricted, as with an increased height of the bushing and installation site, equalization is insured and bushing lube PSI becomes that of the supply PSI.

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

Not applicable.

Not applicable.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to the field of automotive transmissions, and more specifically to an improved bushing for use in a direct clutch drum of a transmission.

Several figures are provided to illustrate the factory-standard structure and corresponding function of the direct clutch drum and bushing to better understand the benefits provided by the present invention.FIG. 1illustrates an assembly of a center support100, a direct clutch drum102, and a forward clutch drum104of a Ford 5R110W automatic transmission (hereinafter, the “Ford transmission”).

FIG. 2illustrates the structure of the factory-standard, or OEM (original equipment manufacturer), direct clutch drum102, which employs an OEM bushing110within a center cylindrical opening105of the direct clutch drum to engage a lube supply114of the center support100. The OEM bushing110includes two cylindrical bushings112vertically spaced within the center cylindrical opening105of the direct clutch drum102. A center cylinder107of the direct clutch drum, defining the center cylindrical opening105, has two transfer ports108located 180° degrees apart. These two drum transfer ports108match two lube supply holes109located on the lube supply114of the center support100. Several balance piston exhaust ports106are spaced around an upper edge of the center cylinder107.

FIG. 3illustrates the OEM bushing110, wherein two narrow cylindrical bushings112together comprise the OEM bushing. The OEM bushing110is sized in diameter to fit within the center cylindrical opening105of the center cylinder107.

FIG. 4illustrates the center support100, and namely how the each cylindrical bushing112of the OEM bushing110would interact with the lube supply114in operation.

In regards to the Ford transmission, the size of the two drum transfer ports108and two supply transfer ports109are important to the operation of a drum bushing. The two transfer ports108are each sized as 0.200 in (inches) or 5.080 mm (millimeters) in diameter, and have a combined area represented by a 0.283 in or 7.188 mm diameter hole. The two supply transfer ports109are each sized as 0.082-0.084 in or 2.083-2.134 mm in diameter, and have a combined area equal to a 0.118 in or 2.997 mm diameter hole. A 0.118 in or 2.997 mm feed with a 0.283 in or 7.188 mm leak (5.67:1 leak to supply area ratio) yields minimal physical restriction and near zero PSI (pounds per square inch), or kPa (kilopascals), in the bushing area, as all flow is dumped to the balance piston through the drum transfer holes. Since the balance piston exhaust ports have a combined area more than double that of the transfer ports, the only pressure generated between the drum bushings is that necessary to push the volume of lube supply out of the vent path.

Although this configuration will keep the bushing area generally charged with lube, it is less than adequate to pump sufficient amounts of lube across the bearing surface of the bushings. This is evidenced by the shortened life and visible bluing of the two narrow bushings. Bluing, or discoloration from heat tempering, is proof of excess friction. This occurs when there is inadequate lube applied to the bearing surface. Conversely, when a bushing surface is adequately lubed it will effectively hydroplane across the supporting surface. The present invention seeks to induce an effect similar to hydroplaning between an improved bushing and supporting surface. Further discussion of the invention is provided in drawings and a detailed description of the invention.

BRIEF DISCUSSION OF THE PRIOR ART

Known after-market bushings have been designed for the Ford transmission in an attempt to increase lubrication, decrease friction, and improve overall performance.FIGS. 5-6illustrate one such example of an after-market bushing for the Ford transmission direct clutch drum.

FIG. 5depicts an after-market bushing210inserted into the center cylindrical opening105of the center cylinder107of the direct clutch drum102. The large openings of the two drum transfer ports214of the after-market bushing210match the drum transfer ports108of the direct clutch drum and therefore do not alter pressure or significantly improve lubrication of the bushing.FIG. 6illustrates the after-market bushing210as depicted inFIG. 5, which includes a single wide cylinder212made out of bronze with two drum transfer ports214positioned 180 degrees apart to correspond and match the two drum transfer ports108and two lube supply holes109of the direct clutch drum102and center support100.

BRIEF SUMMARY OF THE INVENTION

The present invention solves the problem of inadequate lubrication between a center support and direct clutch drum of a transmission by providing an improved cylindrical bushing with multiple channels along an inner service, said multiple channels including at least one central channel oriented in a circumferential manner and at least one channel oriented perpendicularly to the central channel along the height of the bushing, the cylindrical bushing further having one or more openings in the central channel to improve lubrication pressure.

In a preferred embodiment of the improved bushing, the bushing comprises a cylindrical sleeve having an outer surface and inner surface, wherein the outer surface of the cylindrical sleeve is securable to an inner surface of a direct clutch drum cylinder, a central channel extending circumferentially along the inner surface, a lube transfer port located along the central channel and through which a lubricant can pass, and four vertical lube channels extending along the inner surface, the four vertical lube channels each passing perpendicularly through the central channel and each of the four vertical lube channels being spaced at least 90 degrees apart from each of the other four vertical lube channels along the inner surface, wherein an end of each of the four vertical lube channels does not extend to an edge of the inner surface.

A better understanding of the present invention, including the preferred embodiment and further embodiments, will be had when referencing the follows drawings.

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIG. 7, a preferred embodiment of an improved bushing300is shown installed within an OEM direct clutch drum102. The bushing300is installed within the center cylindrical opening105along an inner surface of the center cylinder107to a depth of 0.125 in or 3.175 mm (+/−0.005 in or 0.127 mm) below flush to a washer surface of the direct clutch drum102. The bushing300can also be installed alongside a spacer ring with a height of 0.125 in or 3.175 mm to achieve the same positioning within a center cylinder107of the direct clutch drum102. This position restricts exhaust through the balance piston exhaust ports106to assist with equalizing bushing lube and supply PSI or kPa.

With reference toFIG. 8, a side perspective view of a preferred embodiment of the improved bushing300is shown. The bushing300includes a cylindrical sleeve301having an inner surface302, an outer surface304, a thickness T, and a height H. The thickness T of the sleeve301tapers slightly along the top edge316and bottom edge318. Additional embodiments of the bushing do not have a tapered top edge and/or a tapered bottom edge. The outer surface304of the bushing300rests along the inner surface of the center cylinder107of the direct clutch drum102when installed for use. The inner surface of the bushing300rests along the lube supply114of the center support100when installed for use. Along the inner surface302, a central channel306is formed into the thickness T of the sleeve301along a circumference of the sleeve. At least one vertical channel308is formed along the inner surface302into the thickness T of the sleeve301, wherein the length of each vertical channel extends along the height H of the sleeve301. Each vertical channel308intersects the central channel306perpendicularly. In the preferred embodiment, four vertical channels308are evenly spaced along the inner surface302of the sleeve301, and each vertical channel has a closed end314and an open end310. Each closed end314of each vertical channel308is located near a top edge316of the sleeve301and each open end310is located along a bottom edge318of the sleeve. At least one lube transfer port312is located within the central channel306and bisecting the thickness (T) of the sleeve301. The lube transfer port312allows lubricant to pass between the lube supply114of the center support100and center cylinder107of the direct clutch drum102.

FIGS. 9-13provide further views of the preferred embodiment of the bushing300. The side view ofFIG. 9shows the lube transfer port312positioned within the central channel306and between two vertical channels308. In the preferred embodiment, only one lube transfer port is present. However, two lube transfer ports are contemplated in a further embodiment, with each of the two lube transfer ports positioned 180° degrees from each other within the central channel306. In such an embodiment, the side view illustrated inFIG. 9would be mirrored from the opposite side of the bushing. The lube transfer hole312in the preferred embodiment is 0.093 in or 2.362 mm in diameter, but may range in diameter in other embodiments between 0.062-0.187 in or 1.575-4.750 mm, inclusive. All diameters within said range are smaller than the OEM lube transfer port diameter of 0.200 in or 5.080 mm. Reducing the diameter of the lube transfer port restricts lubricant flow to the balance piston, thereby increasing PSI or kPa in the bushing lube region above near zero to increase lubricant flow.

In the preferred embodiment, the height H of the sleeve301is 1.46 in or 37.084 mm. All known prior art, single piece bushings have a height slightly larger than the OEM bushing, but no larger than 1.26 in or 32.004 mm. All contemplated embodiments of the present invention have heights H greater than 1.30 in or 33.020 mm, as such heights minimize drum rocking, which occurs with an axial misalignment off the centerline.

FIGS. 10 and 11provide a bottom and top view, respectively, of the preferred embodiment of the bushing300. From the bottom view ofFIG. 10, each of the four vertical channels308are seen evenly spaced 90 degrees apart along the inner surface302of the sleeve301. Each vertical channel308has an open end310along the bottom edge318and closed end314near the top edge316, such that the vertical channels are obscured in the top view ofFIG. 11. In the preferred embodiment, each vertical channel308is 0.060 in or 1.524 mm wide and terminates at the closed end314between 0.090-0.100 in or 2.286-2.540 mm from the top edge316of the sleeve301. The width of each vertical channel308is variable, with the width of each vertical channel being smaller than the width of the central channel306. Further, the width of each vertical channel308may taper slightly into the thickness T of the sleeve, or moving from the inner surface302to the outer surface304.FIG. 12provides an enlarged top-down sectional view of one vertical channel308fromFIG. 10. The sleeve301has a thickness T between 0.0622-0.0628 in or 1.580-1.591 mm, providing a range of vertical channel308depths between 0.0142-0.0198 in or 0.361-0.503 mm, inclusive.

While the preferred embodiment of the invention provides four evenly spaced vertical channels308, other embodiments of the invention may include two, three, or more than four evenly spaced channels with dimensions similar to the preferred embodiment. However, four evenly spaced channels are preferred to best distribute lubricant.

FIG. 13illustrates a cross-sectional view of the sleeve301, which provides a view of the dimensions of the central channel306. In the preferred embodiment 300, the central channel306is 0.187 in or 4.750 mm wide. Width of the central channel306may vary, with the width of the central channel being greater than the individual width of each vertical channel308. Further the width of the vertical channel308may taper slightly, moving from the inner surface towards the outer surface. The depth of the central channel306ranges similarly to the depth of each vertical channel308, with a depth between 0.0142-0.020 in or 0.361-0.503 mm, inclusive. The depth of each vertical channel308and the central channel306are the same wherever they fall within the stated range in a given embodiment to prevent pooling of lubricant within either the central channel or vertical channels due to differences in depth.

With reference toFIG. 14, an alternate embodiment of the bushing300′ is shown with vertical channels308′ having a pair of closed ends314′ oppositely oriented along each vertical channel, replacing the view of the preferred embodiment shown inFIG. 9. Beyond having two closed ends314′, all elements, dimensions, and variables regarding the preferred embodiment also apply to the embodiment ofFIG. 14. The view ofFIG. 11would depict both the top and the bottom view, replacingFIG. 10.

In operation, all embodiments of the present invention restrict exhaust at the lube transfer ports108and exhaust/vent ports106to equalize bushing lube PSI or kPa with lube supply PSI or kPa. A hole or pair of holes312in the bushing with an area equal to that of the lube supply holes109in the center support100regulates an intermediate pressure to the bushings of 50% of the supply pressure on its own, regardless of the balance piston. When the balance piston is filled, the added resistance at the transfer orifices will begin to equalize bushing lube PSI or kPa with lube supply PSI or kPa. When the balance piston exhaust/vent ports106are also restricted, as with an increased height (H) of the bushing and installation site, equalization is insured and bushing lube PSI or kPa becomes that of the supply PSI or kPa. The central channel306and vertical channels308on the inner surface302direct pressurized lubricant evenly across the entire inner surface of the bushing300, while the central channel further allows lubricant to flow from a center support supply hole109to the drum transfer port.

The sleeves300and300′, and further embodiments, may be made from industry standard materials typically used for drum bushings, such as metal and metal alloys.