Motor vehicles – Transmission mechanism
Reexamination Certificate
2000-02-15
2001-09-11
Mai, Lanna (Department: 3619)
Motor vehicles
Transmission mechanism
C180S350000, C180S351000, C180S357000, C180S361000, C180S364000, C180S217000, C180S231000, C074S607000, C474S114000
Reexamination Certificate
active
06286619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to drive arrangements for all terrain vehicles. More specifically, the present invention relates to separated engines and final drive assemblies for use in all terrain vehicles.
2. Related Art
All terrain vehicles are constructed for use in all kinds of rough, rocky and uneven terrain. The vehicles generally comprise a frame that defines an engine compartment, an engine positioned within the engine compartments and a transmission that drives a set of wheels with power from the engine. The transmission typically is included within a transmission case that is directly connected to the engine and generally powers the rear wheels through a shaft and differential assembly. Preferably, substantial clearance is maintained between the vehicle and its associated components and the ground over which the vehicle is being operated.
Recently, manufacturers have been down sizing the all terrain vehicles to create a more compact vehicle. As is known, more compact vehicles often weigh less and cost less to manufacture and operate. The lighter weight improves engine performance and eases transportation. Accordingly, to reduce vehicle size, many variations of transmission shaft mounting have been developed. The transmission shafts typically all are positioned near the engine and must be positioned to accommodate the components of the engine.
In addition, manufacturing such compact vehicles has been a difficult task. The engines and the transmissions can be assembled together outside of the vehicle or positioned inside of the vehicle and then joined together. Either method is difficult in production operations. Assembling the engine and transmission as a unit yields a bulky and heavy unit that must be shoehorned into the engine compartment. Yet, placing both components into the engine compartment before securing them together is made difficult due to the small size of the engine compartment.
SUMMARY OF THE INVENTION
Accordingly, an offroad vehicle having a separate engine and final drive has been developed. The two components are positioned within the vehicle and connected by a flexible drive component, such as a chain. The chain is driven by a drive sprocket. The final drive includes a driven sprocket that transfers power to the drive shaft of the rear wheels. The driven sprocket generally is larger than the drive sprocket and, thus, in some arrangements, can disadvantageously depend downwardly into the clearance zone defined between the vehicle's frame and the ground. In addition, tension on the chain can decrease over time such that the vehicle needs to be extensively serviced before the chain disengages from the sprockets. Moreover, when a separated final drive is used, a large reaction force can be set up by the flexible drive component and the final drive should be securely mounted to oppose this reaction force.
Thus, an offroad vehicle is desired in which a final drive and an engine have been separated. The two components should be connected by a flexible transmitter. The tension on the flexible transmitter should be easily adjusted and the driven sprocket should be mounted so as to not depend greatly into the vehicle clearance zone. The final drive should be securely mounted to the frame to counter reaction forces set up during engagement of the engine with the final drive.
Accordingly, one aspect of the present invention involves an all terrain vehicle comprising a frame having a lower frame. At least one rear wheel is mounted to the frame and at least one front wheel is mounted to the frame. An engine compartment is defined within the frame between the front wheel and the rear wheel and an engine is mounted within the engine compartment. A final drive is mounted to the frame separately from the engine. A drive shaft connects the rear wheel and the final drive and the rear wheel is drivingly connected to the engine through the final drive. The drive shaft extends generally transverse to a longitudinal plane that substantially bisects the frame. The final drive is positioned such that at least a portion of the final drive is intersected by the drive shaft. The final drive comprises a driven sprocket and the engine comprises a drive sprocket. The drive sprocket is drivingly connected to the driven sprocket by a flexible transmitter and the driven sprocket is positioned to lie entirely above a plane defined by the lower frame.
Another aspect of the present invention involves an all terrain vehicle comprising a frame, a pair of rear wheels that are rollably mounted to the frame and at least one front wheel that is rollably mounted to the frame. The rear wheels turn about a first axis and the at least one front wheel turns about a second axis. An engine is mounted to the frame between the first axis and the second axis and a final drive is mounted to the frame and is separated from the engine. The rear wheels are drivingly connected to the engine and the final drive is at least partially positioned between the rear wheels. The final drive comprises a driven sprocket and the engine comprises an output shaft and a drive sprocket. The drive sprocket is drivingly connected to the output shaft and the drive sprocket powers the driven sprocket with a flexible transmitter.
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Fukushima Masamitsu
Uchiyama Masayuki
Ilan Ruth
Knobbe Martens Olson & Bear LLP
Mai Lanna
Yamaha Hatsudoki Kabushiki Kaisha
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