Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-12-06
2001-01-16
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06173621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to meshing gear transmissions for transmitting and varying torque and speed from input torque and speed. More specifically, the invention sets forth a compact, constant mesh gear arrangement using uncomplicated shaft forms enabling many different ratios to be realized from a minimal number of gears and shafts. The invention finds utility in the automotive field, broadly defined. The invention is usable in powered motor vehicles wherein wheels, propellers, propulsion screws, and the like must be operated at speeds and torques varying from those of a power plant. Motor vehicles, including automobiles, trucks, and motorcycles are the principal but not sole applications. Of course, machine tools and machinery generally requiring gear reductions may utilize the present invention.
2. Description of the Prior Art
Motor vehicles relying on internal combustion engines having a rotating power output shaft have long had to match power and rotational speed of the engine to actual requirements. In most cases, the engines are high speed, and require reduction in shaft speed from the engine to the driven element, such as powered road wheels. Since power demand for different aspects of vehicle operation varies considerably with conditions, more than one reduction ratio is required. General purpose road going automobiles are currently available with four, five, or six forward speeds. Road going, freight hauling trucks may have sixteen speeds. The greater the number of available reduction ratios, the greater the versatility of the drive train with respect to fuel efficiency, engine life, acceleration, noise, and similar aspects of operation.
Conventional transmissions employ plural spur or helical cut gears. The gears ride on supporting shafts, and are keyed by splines or interface with dogs formed on splined engagement rings or gears to their shafts. The engagement rings are slid along the shaft, turning in lockstep therewith, and mesh with dogs formed on the face of each gear. Gears are provided in meshing pairs, each one of the pair supported on one shaft. The number of gears required to provide a predetermined number of reduction ratios usually exceeds the number of available ratios. Examples are seen in U.S. Pat. No. 971,883, issued to Kenneth W. Gant on Oct. 4, 1910, U.S. Pat. No. 1,064,365, issued to George D. Munsing on Jun. 10, 1913, U.S. Pat. No. 1,277,251, issued to Johann Klaus Ott on Aug. 27, 1918, U.S. Pat. No. 1,362,490, issued to Robert Keck on Dec. 14, 1920, and U.S. Pat. No. 1,415,515, issued to Constant Bouillon on May 9, 1922. In most of these examples, the subject transmission employs conventional elements such as three shafts, these being an input shaft, an output shaft, and a counter shaft, shift forks, and toothed gears which rotate on the three shafts.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention provides a transmission of unparalleled simplicity, which employs three shafts, toothed gears, and engagement rings in a manner which enables at least as many reduction ratios to be available as the number of gears. Three parallel shafts are employed, two having external splines. Freely rotatable gears ride on the two shafts, carried on bearings enabling the gear to rotate independently of its shaft. Each gear has two corresponding gears meshed therewith, each disposed on one other shaft. Therefore, gears permanently meshed to one another occur in associated or meshed groups of three.
Driving relationship of any one gear to its associated shaft is controlled by engagement rings. Each engagement ring can couple either one of two axially surrounding gears of one supporting shaft to that shaft. When any one gear is locked to its shaft by an engagement ring, two other gears supported on the other two shafts are driven thereby as a consequence of the meshing arrangement. The gears are interconnectable such that a driven gear can in turn be drivingly connected directly to a gear permanently meshing therewith and indirectly to any other gear in the gear set. The result is that many final reduction ratios are possible from a gear set having a minimal number of gears.
With three shafts, the total number of reduction ratios for a nine gear transmission can be nine ratios or speeds. For a twelve gear, three shaft transmission, the number of ratios or speeds is sixteen. The number of ratios available from a three shaft transmission is equal to the square of the number of gears on each shaft, when the number of gears on each shaft is equal to the number of gears on each other shaft.
The minimal number of gears leads to several important benefits. One is that the transmission is quite compact for the number of ratios offered. Another is that the transmission is of correspondingly reduced cost for the number of ratios offered. The great number of ratios can be exploited in several ways. It may be desirable to employ all available ratios. Alternatively, it may be desirable to leave some ratios permanently unavailable in some applications or some ratios made temporarily unavailable or idle in other applications. Idling some ratios can be accomplished by a lock out feature which can optionally be overridden or reconfigured to lock out different ratios when adjusted accordingly. Accordingly, it is a principal object of the invention to provide a maximum number of gear reduction ratios for the number of gears employed in a multiple speed transmission.
It is another object of the invention to make transmissions more compact and economical.
It is a further object of the invention to provide sufficient number of gear ratios so that some gear ratios can be idled for a particular application and employed in other applications.
It is an object of the invention to make transmissions of uncomplicated construction, enabling uncomplicated assembly and adjustment.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
REFERENCES:
patent: 971883 (1910-10-01), Gant
patent: 1064365 (1913-06-01), Munsing
patent: 1277251 (1918-08-01), Ott
patent: 1362490 (1920-12-01), Keck
patent: 1415515 (1922-05-01), Bouillon
patent: 2535632 (1950-12-01), Herr, Jr.
patent: 63-312541 (1988-12-01), None
Siemens Patent Services LC
Wright Dirk
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