Planetary gear transmission systems or components – Planetary gearing or element
Reexamination Certificate
2000-03-28
2001-12-11
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Planetary gearing or element
Reexamination Certificate
active
06328668
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to devices for transmitting power from an input source to an output source and more particularly concerns a device for varying the rotational speed ratio between input and output sources.
There are many variable transmissions currently in use for receiving input at a first rotational speed and converting it to output at a second rotational speed. Hydraulic pump or turbine transmissions are costly, complicated and generally inefficient. Split pulley transmissions are generally able to handle relatively low power systems but lose much of their input energy to friction between their pulleys and V-belt. Flat drive plate transmissions also have power input limitations and high frictional power loss. Known positive gear engagement transmissions such as described and illustrated in U.S. Pat. No. 5,360,380, suffer from a variety of limitations. They do not provide an infinite number of ratios to choose from and, therefore, must be shifted in synchronization with an interruption in power, resulting in a jerking motion. Synchronization is necessary to avoid mashing planet gear teeth while the diameter of the ring member is changed so as to change ratios. Timing cams or solenoids could be used for synchronization, but high speed operation requires many components which reduce the cost effectiveness and increase the maintenance requirements of the system. My present U.S. Pat. No. 6,132,330 uses positive gear engagement to transmit power from an input to an output at continuously variable speeds but requires a highly modified input planetary drive gear of a resilient nature not common in conventional engineering.
It is, therefore, an object to the present invention to provide a positive gear engagement transmission which is more reliable than known transmissions. Another object of this invention is to provide a positive gear engagement transmission which greatly reduces loss in power due to friction. A further object of this invention is to provide a positive gear engagement transmission with a continuum of selectable gear ratios with smooth transition from one ratio to the next. It is also an object of this invention to provide a positive gear engagement transmission which minimizes the typical slippage problems associated with non-positive gear engagement drive systems. Still another object of this invention is to provide a positive gear engagement transmission with a continuously variable ratio between the input linear or rotational speed and the output speed, which may be varied continuously. Yet another object of this invention is to provide a positive gear engagement transmission which uses conventional gears without radical modification.
SUMMARY OF THE INVENTION
In accordance with the invention a positive gear engagement transmission is provided which affords a continuously variable ratio between input and output rotational speeds. Thus, the input drive may operate at a desired constant speed while the output speed is varied continuously or the input drive speed may be varied while the output speed is held constant. The power transfer utilizes positive gear engagement throughout because energy is moved from one solid or metal component to another without the use of any resilient medium or fluid such as a rubber belt, friction material or oil. Conventional gears need not be modified because characteristics of resilience are not required by the positive gear engagement transmission.
The positive gear engagement transmission employs a circular rack journalled for rotation about a center axle or hub and having inner and outer arrays of teeth. The arrays of teeth are preferably, but not necessarily, opposed. An inner planet gear has a centered rotational axle and an array of teeth engaged with the inner rack array of teeth. An outer planet gear has a centered rotational axle and an array of teeth engaged with the outer rack array of teeth. The planet gear axles are journalled for rotation on a support structure and the planet gears are linked for counter-rotation about their respective axles. The ratio of the inner rack array of teeth to the outer rack array of teeth is equal to the ratio of the velocity of the inner planet gear along the inner rack to the velocity of the outer planet gear along the outer rack. Linkage can be accomplished by directly meshing the teeth of the planet gears by use of a step gear or by use of a linkage including one or more rotating gears in addition to the planet gears. Such modifications permit the necessary counter-rotation of the planet gears while providing axle orientation and force transmitting structure suitable for specific applications. Any rack, together with its associated planet and other rotating gears and supporting structure and linkage, can be used as a planet gear of another rack.
A force applying mechanism is provided to apply unidirectional or opposing forces upon the axles of the planet gears to accomplish the variation of energy transfer into the rack. When forces to the axles of the planet gears oppose each other in a quantity to cause a balanced pressure between the teeth of the inner planet gear and the rotating gear with which it is engaged, maximum energy transfer occurs. When the opposing force is changed to a point where the forces are in line with each other, a minimum of energy will be transferred. Thus, the useful operating range of any given positive gear engagement transmission can be defined as the line extending at least between the balanced pressure force application point and the minimum energy transfer force application point. The orientation of this line can be changed by use of any suitable mechanical control mechanisms, such as hydraulic actuators, solenoids, counterweights, springs or vector changing structural configurations, to shift the balanced pressure point.
In a standard axle embodiment of the positive gear engagement transmission, the outer planet gear axle is disposed outwardly of the inner planet gear axle and force is applied by any suitable mechanism to the supporting and linking structure at a point inward of the inner planet gear axle so as to effectuate a transfer of power to the rack. Preferably, the force applying mechanism is adapted to apply force or to simulate the application of force to the supporting and linkage structure over a continuum of selectable points along a line extending inwardly from the outer planet gear axle toward the center hub of the rack. The line extends between the center of the outer planet gear axle and at least the point of balanced pressure between the teeth of the inner planet gear and the rotating gear with which it engages. In one application of this embodiment, the distance between the center of the outer planet gear axle and the balanced pressure point is substantially equal to the distance between the planet gear axles multiplied by the velocity ratio. However, a mechanical control mechanism can be used to shift the balanced pressure point.
In an inverted axle embodiment of the positive gear engagement transmission, the outer planet gear axle is disposed inwardly of the inner planet gear axle and the force applying mechanism acts at a point outward of the outer planet gear axle to effectuate the transfer of power to the rack. Preferably, the force applying mechanism is adapted to apply force to the supporting and linkage structure over a continuum of selectable points along a line extending outwardly from the outer planet gear axle away from the center hub of the rack. The line extends between the center of the outer planet gear axle and at least the point of balanced pressure between the teeth of the inner planet gear and the rotating gear with which it engages. In one application of this embodiment, the distance between the center of the outer planet gear axle and the balanced pressure point is also substantially equal to the distance between the planet gear axles multiplied by the velocity ratio. Again, a mechanical control mechanism may be used to shift the balanced pressure point.
In a coincident a
Catalano Frank J.
Wright Dirk
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