Friction gear transmission systems or components – Stepless ratio change
Patent
1994-10-26
1997-07-08
Lorence, Richard M.
Friction gear transmission systems or components
Stepless ratio change
74 84R, 476 54, F16H 1504
Patent
active
056455070
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a continuously variable transmission system, and to a method of providing a continuous variable transmission, for the purpose of converting between two rotary motions or between rotary and linear motion, for use, for example, on vehicles or for controlling the motion of robots or parts of machinery or other equipment requiring servos or rotary or linear actuators. In the automotive industry, the invention is especially, but not exclusively, suitable for use on combustion-engine vehicles in the place of a conventional gearbox and clutch, and on battery vehicles in the place of conventional motor speed control equipment. In the machinery and robotics industries, the invention is especially, but not exclusively, suitable as a precision, high-torque rotary or linear servo mechanism. The invention is also suitable for use in other equipment and vehicles requiring motion, examples of which are pedal cycles, toys, amusement arcade games, training simulators and theme park rides using either fixed track or independent passenger cars.
Conventional combustion-engine vehicles usually couple the engine to the wheels via a friction or fluid clutch and a set of discrete gears, shifted manually or automatically. Such arrangements provide only limited optimisation of the engine's fuel economy and torque transfer characteristics. Some vehicles do use continuously variable transmissions, typically employing a system using a belt or chain trapped between two cones that move together and apart altering the effective diameter of the drive hub, but these tend to be less reliable and efficient and capable of transmitting less torque. Various other kinds include: friction drives involving metal spheres and surfaces making contact via a lubricant shear--these suffer from the need for high internal forces compared to the torque transmitted; hydrostatic drives that drive hydraulic motors using variable displacement pumps--these tend to be comparatively expensive; and ratcheting drives which generate a variable amplitude oscillating motion, rectifying this motion to produce output speed--these tend to be complex internally and suffer from a superimposed oscillation on the transmission ratio.
Conventional battery vehicles usually use direct current motors controlled by power electronics or switched resistors. Some vehicles use regenerative braking which returns some of the kinetic energy of the vehicle to the battery as it slows down. The major disadvantage of this arrangement is that conventional friction braking needs to be utilised in addition to regenerative braking, as the energy losses at low speed in the motor and power electronics prevent a substantial amount of the kinetic energy from being recovered.
Conventional actuators and servos are usually based around either a direct current motor coupled to an optical shaft encoder or a stepping motor, both arrangements being controlled by power electronics. The sizes of the motor and the driving transistors increase with an increasing requirement for torque, and the combined costs rise increasingly rapidly with size. Furthermore, an individual servo motor and amplifier is needed for each axis of motion, and a mechanical arrangement, such as a ball-screw, is needed to convert from rotary to linear motion. For very large forces, servo-hydraulics is used which is more costly still.
It is the object of the present invention to provide an improved continuously variable transmission system.
The present invention provides a continuously variable transmission system comprising: free to rotate about their own axes of rotation and having perimeter regions cooperating with the surface at respective regions of cooperation in such a manner that substantial slippage of each rotary member relative to the surface in a direction parallel to the axis of rotation of the rotary member is prevented, axis, of motion relative to one another, the first kind of motion being relative rotation of the common member and the surface about an axis which is fixed relative to the common me
Eryx Limited
Grabow Troy
Lorence Richard M.
LandOfFree
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