Motorcycle drive assembly with improved...

Motor vehicles – Special wheel base – Having only two wheels

Reexamination Certificate

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Details

C180S374000, C123S1960AB

Reexamination Certificate

active

06241040

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to motorcycle drive assemblies. In particular, the present invention relates to transmission-to-engine mountings for motorcycle engines.
BACKGROUND OF THE INVENTION
Motorcycles are widely used for transportation and recreation. Motorcycles are typically powered by a drive assembly including an engine for generating power and a transmission for adjusting torque and speed. In one well-known motorcycle, the drive assembly comprises a left side drive layout wherein the engine includes a crankshaft or output shaft substantially parallel to an input shaft of the transmission. Power from the engine is transmitted to the transmission with a primary belt or chain interconnecting the parallel output and input shafts of the engine and transmission, respectively. The well-known drive assembly additionally includes a primary drive housing for enclosing the primary belt or chain interconnecting the parallel output and input shafts.
Over time, this left side drive layout has become one of several characteristic features that motorcycle enthusiasts identify as representative of quality and craftsmanship. Maintaining these characteristic features in new motorcycle designs is desirable to preserve the heritage of this popular motorcycle design. However, in many cases, these characteristic features demanded by motorcycle enthusiasts present obstacles to further development of the motorcycle. Thus, the challenge posed by these obstacles has been to improve the performance of the motorcycle while maintaining the traditional visual aspects of the motorcycle.
In this well-known motorcycle drive assembly, the engine and the transmission are typically mounted together by means of generally flat horizontal cantilevered pads that overlap one another at a rear of the engine crankcase and at a front of the transmission case. The two horizontal pads are typically held together by two vertical screws. To maintain proper alignment between the engine and the transmission, the primary housing extends across and bolts to the left sides of both the engine crankcase and the transmission case.
The lubrication system of the drive assembly typically comprises an oil pan, an oil return hose and an oil intake hose. The oil pan acts as a reservoir and contains oil while the oil is de-aerated and cooled. To provide the drive assembly with a compact configuration, the oil pan can be mounted remote or separately from the engine adjacent and below the transmission case. Unfortunately, due to the oil pan's positioning adjacent to the transmission case, the lubrication system requires lengthy hoses extending from the oil reservoir to the engine for providing oil to, and receiving oil from, the engine. These lengthy hoses require critical space, are prone to failure, and can be aesthetically unattractive.
SUMMARY OF THE INVENTION
The transmission of power from the output shaft of the engine to the input shaft of the transmission across the belt or chain generates large loads and a large amount of torque. Because the crankcase of the engine and the transmission case of the transmission are held together by two vertical screws, which react to shear loads at the interface of the crankcase and the transmission case, the interface acts like a hinge. As a result, the primary housing extending across and interconnecting the engine crankcase and the transmission case experiences high loads. The high loads can create misalignment between the engine and the transmission.
There is a continuing need for a compact, stiffer drive assembly that reduces the loads placed upon the primary drive housing and which more effectively circulates oil between the oil reservoir and the engine.
The present invention provides an improved motorcycle drive assembly that satisfies one or more of these needs. In one aspect of the invention, the drive assembly includes an engine having an output shaft, and a transmission having an input shaft substantially parallel to the output shaft and coupled to the output shaft (e.g., by a chain or belt). The engine additionally includes a crankcase having a first interface portion with a first non-horizontal (e.g., substantially vertical) mounting surface. The transmission additionally includes a transmission case having a second interface portion with a second non-horizontal (e.g., substantially vertical) mounting surface butting against or interconnected with the first non-horizontal mounting surface to achieve improved alignment and stability. Preferably, the mounting surfaces are substantially I-shaped to further enhance the engine-transmission interface.
In another aspect of the present invention, the crankcase and the transmission case define a cavity therebetween for housing at least one oil conduit that provides oil flow between the engine and the oil reservoir. Preferably, there are two conduits: one providing oil flow to the engine and one providing oil flow away from the engine.
In another aspect of the present invention, the drive assembly includes an oil reservoir adjacent to the transmission case. The second interface portion of the transmission case at least partially defines at least one oil passage in fluid communication with the oil reservoir.


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1994 Custom Chrome Catalog; p. 170.
1993 and 1994 -1340 Models Parts Catalog; pp. 44 and 48.
Vintage Motorcycle Road Tests, 'Online! XP-002145070 <URL: www.squirrel.com.au
etbikes/roadtests/meteor.htm> Received on Aug. 16, 2000.

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