Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-10-27
2001-03-20
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06202499
ABSTRACT:
TECHNICAL FIELD
This invention relates to an automotive transmission and more particularly to a low inertia drive train transmission especially adapted for use in racing vehicles.
BACKGROUND OF THE INVENTION
Over a period of time the weight of racing vehicles has been reduced and engine horsepower increased. With reduced weight and increased engine power, transmissions with three or more forward gear ratios are not required, and transmissions have been modified to reduce the number of forward gear ratios.
The modified transmissions conventionally have two forward gears and one reverse gear and have improved the performance of racing vehicles. However, these modified transmissions have several objectionable characteristics. For example, their cases are larger and heavier than is required. A countershaft is driven constantly, thereby not only consuming power, but also churning the lubricant and heating the entire transmission assembly. The inertia due to the rotating parts is excessive and impedes both acceleration and deceleration.
Several proposals have been made to overcome the disadvantages described. For example, the engine flywheel has been eliminated from the drive train thereby decreasing inertia and improving acceleration as well as deceleration. However, removal of the flywheel also eliminated the starter ring gear that generally was mounted on the periphery of the flywheel.
Clutches have been added to eliminate rotation of the countershaft gearing when the transmission is shifted into direct drive. These clutches have limited useful lives, may cause lubricant leaks, and require major disassembly of the entire transmission when replacement is required.
Elimination of the flywheel and the starter ring gear precludes the use of conventional engine starting systems. In one proposal the engine starting system is provided by connecting a ring gear carrier plate to a starter, like that used in combination with a torque converter, in lieu of the flywheel. A conventional starter has a drive gear that engages the ring gear to start the engine. The added ring gear carrier and an attached ring gear become, in effect a lightweight flywheel that rotates whenever the engine is running, thereby resulting in undesirable drive train inertia.
SUMMARY OF THE INVENTION
A vehicle transmission constructed in accordance with the invention has appreciably reduced rotational inertia. It includes a countershaft driven by a wet clutch pack assembly that can be replaced without removing either the countershaft or the output shaft. The transmission includes an electric starter for the engine that cranks the engine through a gear train and clutches.
The transmission has a housing, an input shaft, an output shaft, and a countershaft. The input shaft is journaled in a bore through a clutch pack mounting plate. The forward end of the input shaft is connected directly to the crankshaft of an engine and rotates therewith. A clutch housing is journaled on the rear portion of the input shaft. A first friction surface on the clutch housing is movable into engagement with a second friction surface rotatably fixed to the input shaft by a hydraulic piston in a cylinder in the clutch mounting plate to lock the clutch housing to the input shaft. Bolts clamp the clutch mounting plate to the transmission housing with a clutch housing inside the transmission housing. A countershaft drive gear is attached to the clutch housing and is in mesh with a countershaft driven gear. A low-speed forward drive gear and a reverse drive gear are mounted on the countershaft and secured to the countershaft driven gear. An output shaft is journaled in the transmission housing coaxially with the input shaft. A reverse driven gear and a low-speed driven gear are rotatably journaled on the output shaft. The low-speed driven gear is in constant mesh with the low-speed forward drive gear. A reverse idler gear is in constant mesh with the reverse drive gear and the reverse driven gear.
A first slider is splined on the output shaft and is slideable selectively from a neutral position to a first engaged position in which the output shaft is coupled to the input shaft or to a second engaged position in which the low-speed driven gear is coupled to the output shaft. A second slider is splined on the output shaft and is axially slideable from a neutral position to a forward position in which the reverse driven gear is coupled to the output shaft.
An electric starter is mounted on the transmission housing. A starter drive gear drives the reverse idler gear through a series of reduction gears and a one-way clutch. To crank the vehicle engine, the starter motor drives the starter drive gear, the reduction gears, and the reverse idler gear. The reverse idler gear drives the countershaft gears and the countershaft drive gear attached to the clutch housing. When the hydraulic piston is pressurized to engage the clutch in the clutch housing, the engine may be cranked by the starter motor. A one-way clutch in the series of reduction gears prevents the engine from driving the starter at high speed.
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Brinn, Inc.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
Wright Dirk
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