SPLIT DRIVE TRAIN

BACKGROUND

A clutch replacement usually involves the removal of an automobile transmission or engine, which is a major disassembly of the vehicle. Most of the cost and expense of a clutch replacement involves dropping the transmission or removing the engine when necessary. However, the actual replacement of the clutch assembly is fairly simple, and accounts for a small amount of time for the entire repair.

Conventionally, the sole purpose of the removal of the transmission is to remove the input shaft from the clutch assembly so the clutch can be repaired. Clutch replacements, like brake pad replacements, are considered items of wear, and therefore are the responsibility of the owner. Therefore, the ability to change the clutch without removing the transmission provides a major benefit to the vehicle owner. However, the design of conventional drive trains makes repairing the clutch difficult and expensive. Accordingly, improvements to an engine drive train may facilitate the repair of clutches.

SUMMARY

The disclosure herein provides for several improvements over conventional transmissions because they allow for easy removal and/or replacement of a vehicle clutch. In operation, a multipart drive shaft with a transmission portion coupled to a vehicle transmission, may have threading about a portion of an exterior surface. Also included is a spline gear, also with similar threading about a portion of its exterior surface. Between the transmission portion and the spline portion is a coupling, which has similar threading about an exterior surface. The coupling includes a first mating surface removably associated with a complimentary mating surface on the spline gear and a second mating surface removably associated with a complementary surface on the transmission portion. The coupling, spline gear, and transmission portion are secured in place with a threaded sleeve which may have a threaded interior surface configured to mate with the outer surface of the coupling, spline gear and transmission portion. Together the transmission portion, coupling, and spline gear make up a portion of a vehicle drive train.

Because the coupling is slidably mounted between the transmission portion and the spline gear, it can be removed when the threaded sleeve is removed. Once the coupling is removed, the spline gear can be slid back from the clutch assembly over a part of the transmission portion, which, if the spline gear is appropriately sized, will allow the spline gear to drop out of a pilot bushing in an engine block. The clutch assembly will then have clearance to drop out of the drive train without necessitating removal of the transmission or engine.

The construction and method of operation of the invention, however, together with additional objectives and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a partially cutout side view of a common clutch assembly compared to an embodiment of the present disclosure.

FIG. 2 shows an embodiment of a throw-out bearing according to the current disclosure.

FIG. 3 shows an embodiment of a front transmission cover.

FIG. 4 shows an embodiment of a portion of a splittable input shaft.

FIG. 5 shows various alternative embodiments of different ways to split the input shaft.

FIG. 6 shows an embodiment of a threaded sleeve.

FIG. 7 shows multiple embodiments of ways to hold a threaded sleeve in place.

FIG. 8 shows several embodiments of a way to secure a threaded sleeve to a spline gear.

DESCRIPTION
Generality of Invention

This application should be read in the most general possible form. This includes, without limitation, the following:

References to specific techniques include alternative and more general techniques, especially when discussing aspects of the invention, or how the invention might be made or used.

References to “preferred” techniques generally mean that the inventor contemplates using those techniques, and thinks they are best for the intended application. This does not exclude other techniques for the invention, and does not mean that those techniques are necessarily essential or would be preferred in all circumstances.

References to contemplated causes and effects for some implementations do not preclude other causes or effects that might occur in other implementations.

References to reasons for using particular techniques do not preclude other reasons or techniques, even if completely contrary, where circumstances would indicate that the stated reasons or techniques are not as applicable.

Furthermore, the invention is in no way limited to the specifics of any particular embodiments and examples disclosed herein. Many other variations are possible which remain within the content, scope and spirit of the invention, and these variations would become clear to those skilled in the art after perusal of this application.

Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Read this application with the following terms and phrases in their most general form. The general meaning of each of these terms or phrases is illustrative, not in any way limiting.

Lexicography

The term “drive train” generally refers to the parts of a vehicle that transfer power from an engine to the driving axles.

The term “crankshaft” generally refers to a shaft consisting of a series of cranks and crankpins to which the connecting rods of an engine are attached.

The term “drive shaft” generally refers to the part of a vehicle that transfers power from a gearbox or transmission to the wheels.

DETAILED DESCRIPTION

A conventional clutch assembly consists of many small parts, but usually has five major components, the flywheel, the pressure plate, the clutch disk, the throw-out bearing and transmission input shaft.

The flywheel is connected directly to the engine crankshaft and, therefore, spins with the engine's motions. Bolted to the clutch flywheel is the second major component, the clutch pressure plate. The spring-loaded pressure plate has two jobs: to hold the clutch assembly together and to release tension that allows the assembly to rotate freely. Between the flywheel and the pressure plate is the clutch disc. The clutch disc has friction surfaces similar to a brake pad on both sides that make or break contact with the metal flywheel and pressure plate surfaces, allowing for smooth engagement and disengagement.

The throw out bearing and release system work together simultaneously to engage and disengage the process. The clutch release bearing is connected to one end of the clutch fork mechanism and rides on the diaphragm spring of the clutch. Depending on the type of release system, the throw-out bearing either pulls or pushes on the pressure plate diaphragm spring to engage or disengage the pressure plate's grip on the clutch disc when the clutch pedal is depressed and released.

Running through the center of the pressure plate, clutch disc and flywheel is the input shaft of a conventional transmission system. The shaft takes the input, or power of the engine, and sends it down through the gears to the wheels. At the point where the input shaft enters the transmission is a beefy bearing that bears most of the shaft's spinning load. In the middle of the crankshaft/flywheel is a much smaller pilot bearing. The pilot bearing centers the input shaft in the center of the crankshaft/flywheel so it can rotate while the clutch assembly is engaged and disengaged. The input shaft is what the clutch disc itself is connected to.

References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure or characteristic, but every embodiment may not necessarily include the particular feature, structure or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to effect such feature, structure or characteristic in connection with other embodiments whether or not explicitly described. Parts of the description are presented using terminology commonly employed by those of ordinary skill in the art to convey the substance of their work to others of ordinary skill in the art.

FIG. 1 illustrates a partially cutout side view of a clutch assembly. FIG. 1A shows a conventional clutch, whereas FIG. 1B shows a portion of an embodiment according to the current disclosure. Conventionally, vehicles would be designed with inspection pans allowing access to a clutch assembly through the bottom of the transmission bell housing. Modernly, bell housings are cast as part of the transmission and do not include an inspection pan, however, to effectuate some of the embodiments herein, a portion of the bell housing may need to be removed as in conventional inspection pan systems.

A pressure plate 110 covers a portion of a clutch assembly. A transmission input shaft 112 extends into a pilot bushing 114, and the flywheel 116 is partially shown for reference. The pilot bushing 114 is recessed into the crankshaft flange 115 at the end of the input shaft 112. As can be seen in FIG. 1A, to remove the clutch assembly requires pulling the clutch assembly away from the pilot bushing 114 until the input shaft 112 clears the pilot bushing 114 enough for the pressure plate 110 to be completely removed.

The embodiment shown in FIG. 1B includes a shortened input shaft 120 and a modified pilot bushing 118. In FIG. 1B the pilot bushing 118 is modified to have an edge flush with the flange 117. Moreover, the input shaft 120 may be shorted so it does not extend far into the bushing 118. The depth of the input shaft may be range from ⅜ inch to 1 inch in certain embodiments, and other suitable dimensions as required in other embodiments of the disclosure.

When minimizing the depth that the input shaft engages the pilot bushing 118, it may not be necessary to bevel the front edge of the input shaft to such a degree as conventional input shafts because, with the embodiments shown herein, the input shaft may now be installed separately from the transmission in a much easier fashion, thus providing an additional benefit of a larger total shaft surface area to engage with the inner surface of the pilot bushing 118 despite its shortened length.

Clutch Fork

Conventional clutch forks may be installed having a fixed rivet and clamp, or another type of fastener. In certain embodiments the transmission clutch fork may need to be installed with a removable attachment. Removable fasteners such as screws, nuts and bolts, and the like may be preferable to facilitate removing the clutch fork assembly. In certain embodiments, when the inspection pan makes up the bottom portion of the opening for a clutch fork attached to a bell housing, removal of the inspection pan then creates an opening to remove the clutch fork by dropping it down and out of the way.

Throw Out Bearing

FIG. 2 shows a side and end view of an embodiment of a throw-out bearing according to the current disclosure. Conventionally, a throw-out bearing is a part of an automotive clutch system that temporarily disengages the engine from the manual transmission while shifting. It translates a linear thrust force from the clutch pedal to the spinning clutch plate assembly mounted to the flywheel. A conventional throw-out bearing is often press-fit into a sleeve for holding it in place. In FIG. 2 throw out bearing 210 includes a tab 214 extending into a removable throw-out bearing sleeve. The throw-out bearing sleeve is split into two parts, an upper throw-out bearing sleeve 216 and a lower throw-out bearing sleeve 218 for positioning around a front transmission cover/input shaft (not shown).

The throw-out bearing sleeves are formed to have a channel (or recessed area) 220 extending into the center portion of the upper 216 and lower 218 sleeve so that when the upper sleeve 216 and lower sleeve 218 mate together they form the channel or recessed area 220. The tab 214, the race 228 and the channel 220 are formed to mate such that the assembled sleeve (the upper and lower portions when joined) couples to the tab 214, and consequently the throw-out bearing 210, when assembled. The tab 214 may include flat surfaces for reducing torsion between the sleeves and the throw-out bearing. Thus the throw-out bearing will not rotate because of tab 214, it will be stable because of channel 220 and will not move forward because of race 228.

The upper sleeve 216 and the lower sleeve 218 may, in one embodiment, be fastened together with a screw 212 by forming a tapped receiver 222 in the upper sleeve 216 and a through-hole 224 in the lower sleeve 218 as shown. The sleeves may also be fastened using any number of conventional means such as nuts and bolts, or by other suitable fastening devices. In operation, a standard sized hex nut which is clearly accessible may be preferred, however clearances within the, or in the event of a failure, may necessitate alternative means.

With the splitting and removal of the throw-out bearing sleeve, the redesigned throw-out bearing can be slid back toward the gear box exposing the front transmission cover.

Front Transmission Cover

FIG. 3 shows an embodiment of a front transmission cover. The front transmission cover is designed to cover the input shaft at one end of a transmission and allows for the throw out bearing to slide back and forth during operation. For easy removal of the transmission cover, it may be split into two parts to form a tube as shown in FIG. 3A. The transmission cover may include a top part 310 and a bottom part 312 which are formed to mate together, as shown in FIG. 3B. Mating may be effectuated by having complementary, slanted grooves (or teeth) 316 which mate by pushing at an angle, and allow for the cover to be sealed. With the teeth on one part of the tube angled into the slots on the other half of the tube as shown, the tube cannot be pulled apart once screwed into place. Notches 318 on each side of the front cover may provide a recess to insert a screw driver in order to pry the two halves apart if necessary. When mated, the transmission cover part 310 and bottom part 312 form a threaded end 320.

Slots 314 are cut into the tube in one embodiment to allow for gripping with a wrench. In some embodiments the two parts 310 and 312 may be held together with screws (not shown) or another suitable fastener means. Moreover, the two parts 310 and 312 may snap together and be held by a lock washer 319 disposed over the threaded end 320.

FIG. 3C shows a partial break-away drawing of one embodiment of a transmission cover enclosing an input shaft 322. A second, circular cover, or stub 324 also encloses the input shaft 322. The stub 324 has a (female) tapped receiver section 326 for mating to the (male) threaded end 320 of the tube. When installed, the tube's threaded end 320 fits into the receiver section 326. In other embodiments, the male and female tapped and threaded portions may be reversed on the respective receiver section 326 and threaded end 320.

In operation the front transmission cover may be removed by unscrewing it from the stub 324 and prying the top part 310 and the bottom part 312 apart (removing any lock washer if present) thus allowing access to the input shaft 322.

Split Input Shaft

FIG. 4 shows an embodiment of a portion of a splittable input shaft shown in an exploded configuration A. To remove the input shaft from a transmission may require that the input shaft be splittable and that a section of the input shaft be removable. As shown in FIG. 4 the input shaft can be split into three parts, transmission (or rear) part 410, a coupling (or center part) 412 and a front part 416 that includes a spline gear on the outer surface of part 416.

As shown, the exterior parts of the input shaft split are threaded in a complementary manner to allow them to be joined together with other hardware described herein. The transmission part 410 is attached to the transmission and has a threaded nipple 411. Extending from the threaded nipple 411 is a threaded tab 424. The threaded tab 424 extends across the face of the nipple 411 as shown in FIG. 4B. The mating surface of FIG. 4B is a tongue-in-groove surface with the tongue and groove extending all the way across the mating surfaces.

The coupling 412 includes a notch 418 which extends across the coupling 412. The notch 418 is designed to provide a snug fit for tab 424 such that the threads on the exterior surface of the nipple 411 and the exterior surface of the coupling 412 provide a smooth continuous thread. In some embodiments, the notch 418 and tab 424 need not extend completely across the center of their respective members. The notch 418 has a predetermined width (such as for example, but not limited to ¼-inch) and a threaded extension part 420, which is larger than the notch 418. For example, and without limitation, the extension 420 may be ⅜-inch diameter.

The spline gear 416 also includes a threaded tab 414 and a notch 422. The notch 422 is sized to receive the threaded tab 420 from the coupling 412. The tab 420 mates to the notch 422 in a similar fashion as tab 424 mates to notch 418. The notch 422 is shown larger than notch 418 to allow for the spline portion 416 to slide over the tab 424 when the coupling 412 is removed.

In operation, the coupling 412 may be removed by sliding the center part 412 out from between the tab 424 and out of the notch 422. Since the notches extend completely across the shaft, the coupling 412 may be removed in one of two different directions, being along the axis of the notch. Once the coupling 412 is removed, the spline gear 416 may slide towards the rear part 410 such that receiver 422 slides over the tab 424 and becomes free of the other portions. The distance the spline gear 416 needs to move will depend on how far into a pilot bushing the spline gear 416 is inserted.

Input Shaft Strength

Another embodiment of the shaft split is shown in FIG. 4C. FIG. 4C shows a notch that may be used on the coupling 418 or the spline part 422. By not extending the notch all the way across the shaft, there may be increased structural integrity of the input shaft, however, the coupling 412 may only be removed in a single direction, being along the axis of the notch in the direction that the notch opens.

FIG. 5 shows various alternative embodiments of different ways to split the input shaft. In FIG. 5, there is a rear part 510, a center part 512 and a front part 514 featuring a spline structure on its surface. While a 5-point spline (gear) structure is shown, this disclosure should not be limited. For example and without limitation, poly-drive, double-hex and similar type shapes may also be employed in certain embodiments. The front part 514 has a slightly elongated shaft 516 for insertion into a pilot bushing as described herein. The center part 512 may have gears formed on each end, and those gears may mate with complementary gear receivers on the respective rear and front parts. Representative spline gear patterns are shown in FIG. 5B and FIG. 5C, however, this disclosure should not be read to limit these shapes in any way, as other suitable shapes and complementary voids can be substituted which can provide removable but robust coupling capable of transmitting high torque through the assembled input shaft.

By forming the center part 512 to have one aspect of a gear, as an example embodiment, a male pattern can be selected having a matching (complimentary) female gear pattern on the rear part 510. Similarly, the center part 512 could couple to the spline gear 514. In effect a spline and hub structure is formed. In certain embodiments the center part 512 may be symmetrical by having equivalent gears on both ends thus allowing for insertion in either direction. In other embodiments, the gear pattern may be different on each end so that the center part 512 only fits in one way. This may be preferable to align the exterior threading. Alternative embodiments may include increasing the diameter of the input shaft, the throw-out bearing and other members to maintain the strength of the input shaft.

In operation, notches 518 may be formed in the center part 512 to allow a user to pry apart the center part 512 from the spline gear 514. When prying, the elongated shaft 516 would extend further into the pilot bushing thus allowing for room between the center part 512 and the spline gear 514, so that the center part 512 may be removed without displacing it or the rear part 510.

Threaded Sleeve

FIG. 6 shows an embodiment of a threaded sleeve. The threaded sleeve 610 operates to provide alignment for the parts of the split input shaft described herein. The threaded sleeve may provide vertical support as well as keeping the three sections from any lineal or undesired movement or distortion under torque. Interior to the sleeve 610 is internal threading 614, which forms a continuous threaded interior, such that the sleeve 610 may travel back and forth over the split input shaft parts. The three sections of the input shaft should be held firmly, and therefore it might be preferable for the sleeve 610 to use a medium sized internal thread of between 6 to 16 threads per inch (TPI). In various embodiments, threads from small (higher TPI) sizes to large (fewer TPI) may be suitable. The sleeve may include one or more service holes 616 that allows for a user to inspect an input shaft when the sleeve is disposed over a split input shaft as shown in top view FIG. 6A.

The threaded sleeve 610, may also be anodized to pacify the surface, or surface treated by conventional means to reduce rust or other friction in order to facilitate its removal. The rear of the spline gear may also need to be machined flat, so the sleeve can tighten against the collar. The exterior shape of the threaded sleeve 610 may vary widely, and is only shown as hexagonal as a representative example embodiment. The hexagonal shape allows for gripping the sleeve 610 with a wrench, however other shapes and tools may be employed to effectuate gripping of the sleeve 610. A hexagon will have a larger diameter than a circular design, but a circular design may require a special wrench, such as a spanner wrench, to work with the sleeve 610.

FIG. 7 shows multiple embodiments of ways to hold a threaded sleeve in place. In operation the threaded sleeve moves along the multiple parts of a split input shaft from the front part to the transmission cover part, because the split input shaft has threading running along its length. In the embodiment of FIG. 7A the threaded sleeve may be held in place using a cotter pin 714 positioned at an end of the sleeve, away from the front part. In the embodiment of FIG. 7B, the cotter pin(s) 714 may extend into the sleeve 710, through an input shaft and out of a bottom part of the sleeve 710. Other embodiments may include bending the exposed portion of the cotter pin 714 back along the input shaft to facilitate size or installation constraints. Some embodiments may include the use of a reverse thread to hold the sleeve in place against any rotational force imposed upon it. Depending on the rotation of the input shaft, the threading may be optimized to effect a secure fitting over the input shaft coupling. In alternative embodiments, a lock washer may also be employed to hold the threaded sleeve in place and coupled to the spline gear. In some embodiments the threaded sleeve could be designed similar to a lock nut to prevent unwanted rotation.

FIG. 8 shows several embodiments of a way to secure the threaded sleeve to a spline gear. In FIG. 8 the threaded sleeve 810 is shown from an end view. In some embodiments a collar 814, shaped to conform to the threaded sleeve, has metal, flexible tabs 816 attached about the periphery. The tabs may be spaced to correspond to grooves on a spline gear and disclosed herein. Placing the collar 814 over the spline gear portion of the split input shaft before completely assembling the split input shaft assembly allows for tightening the collar and threaded sleeve to the spline gear. Moreover, since the tabs are spaced in a manner complementing similar spacing as that of the grooves on the spline gear, multiple tabs may be folded over the spline gear for increased stability.

Operation

In operation, a multipart drive shaft with a transmission portion coupled to a vehicle transmission may have threading about a portion of an exterior surface. Also included is a spline gear, also with similar threading about a portion of its exterior surface. The spline gear extends into a clutch assembly. Between the transmission portion and the spline portion is a coupling, which has similar threading about an exterior surface. The coupling includes a first mating surface attached to a complimentary mating surface on the spline gear and a second mating surface attached to a complementary surface on the transmission portion. The mating surfaces are designed to let the coupling either slide out of place, or be removed by sliding the spline gear towards the clutch assembly. The coupling, spline gear and transmission portion are secured in place with an anodized threaded sleeve which has a threaded interior surface that is able to mate with a correspondingly receptive outer surface of the coupling. Together the transmission portion, coupling, and spline gear make up a portion of a vehicle drive train.

Because the coupling is slidably mounted between the transmission portion and the spline gear, it can be removed when the threaded sleeve is removed. Once the coupling is removed, the spline gear can be slid back from the clutch assembly over a part of the transmission portion, which, if the spline gear is appropriately sized, will allow it to drop out of a pilot bushing in an engine block. The clutch assembly will then drop out of the drive train without necessitating the displacement of either the engine or the transmission.

System Benefits

Easy replacement of a clutch benefits consumers because of the significant cost reduction for repairing a vehicle with a damaged clutch. A replacement of the clutch may occur several times in the life of the vehicle. Assuming a clutch life of 75,000 miles is average, a passenger vehicle may have a couple of clutch changes in its life. The actual savings is the amount of time required to remove and replace the transmission in a particular vehicle times the hourly rate of the repair shop.

Besides changing a clutch, other repairs may also be facilitated using the methods and devices disclosed herein. For example, replacing leaking seals, a damaged flywheel, or a crankshaft without removing the engine.

The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims.

Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.

SPLIT DRIVE TRAIN

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CPC

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Abstract

Description

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