Friction gear transmission systems or components – Forward and reverse – Variable speed in forward or reverse
Reexamination Certificate
1998-04-02
2001-02-13
Ta, Khoi Q. (Department: 3622)
Friction gear transmission systems or components
Forward and reverse
Variable speed in forward or reverse
C476S036000, C475S248000, C475S221000, C074S66500G
Reexamination Certificate
active
06186922
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to mechanical power transmissions, and more particularly, to transmissions with counter-rotating outputs, preferably located on the same central axis as the input.
Speed conversion is an important capability in the efficient utilization of rotary motive force. The occasion often arises for increasing or reducing of the speed of a drive member to a higher or lower speed at a driven member. In automobiles, for example, a hydraulic transmission, with various combinations of gear assemblies, accomplishes the task of converting the high rotary speed of the gasoline engine to the lower rotational requirements at the driven axle. Typically, such transmissions are quite complex, requiring many parts to operate in sophisticated syncopation, and are quite labor intensive for both assembly and service. Other speed conversion applications include water vessels with single and counter-rotating propellers. Typically in these applications, the speed reducer housing is mounted (“grounded”) directly to the equipment housing to react the transmission forces.
At times the effect of speed conversion (e.g., speed reduction) is also referred to as torque conversion (e.g., torque amplification). It will be further appreciated that the terms speed reducer and torque increaser are thus related as are the terms speed increaser and torque reducer, for purposes of this disclosure.
It is an object of the present invention to provide a speed converter which is simplified in nature but is robust in transmission capability.
It is a further object of the present invention to provide a speed converter which is relatively easy to assemble and service.
It is an additional object of the present invention to provide a speed converter design which is adaptable to provision of counter-rotating outputs.
It is yet an additional object of the present invention to provide a rotary motion converter design which is adaptable to provision of counter-rotating outputs.
SUMMARY OF THE INVENTION
These and other objects are well met by the presently disclosed, highly efficient, speed converting power transmission assembly with counter-rotating outputs. The invention is directed to provision of clockwise and counter-clockwise rotating outputs in an “in-line” manner, i.e., having the input and output shafts on the same central axis.
In a preferred embodiment of the invention, apparatus is provided for converting a rotary input to a rotary output, having a primary cam for providing a rotary input in a first direction, and then a secondary cam to interact therewith via rolling elements. For ease of presentation, these cams, cam tracks or discrete cams are generally referred to below as cams. Either the primary or secondary cam has a plurality of cycles. These cycles at times may appear to be tooth-like and are referred to below either as cycles or as teeth without distinction.
In embodiments of the invention, the primary and secondary cams are for mounting on a common axis along with an intermediate disk either radially or axially in between them. The intermediate disk has a series of slots for receipt of interacting elements such as balls or rollers (for simplicity these are generally referred to (either as balls or rollers below). An important function of the intermediate disk is that it is a direction-dictating (i.e., “directional”) element, such that it dictates reversing or non-reversing output, depending upon the inter-slot angle (slot angle for short). At least one of the three disks is an input disk, at least one is an output disk and at least one disk is a reaction disk (i.e., it reacts the drive forces being applied from the drive disk to the driven disk via the interacting elements). In the preferred embodiments of the invention, the interacting elements move radially in radial slots of the invention, although analogous axial configurations are also within the spirit of the invention. Various embodiments use either disks or cylinders with or without open centers (for simplicity all generally referred to as disks below).
The below description can be applied to various embodiments and should be understood to do so, even though one or another embodiment is shown or described for ease of description. In other words, the following description is provided by way of illustration and not limitation.
In one radial embodiment of the invention, the primary and secondary cams are each formed on a face of a respective primary and secondary disk. Each of the primary and secondary cams has various flank portions. A respective ball in a respective radial intermediate disk slot is oscillated between a maximum and maximum radius by the primary cam. In one embodiment, the slotted intermediate disk is a grounded reaction disk for reacting the drive force on the balls in the slots, and the secondary cam is a driven disk which is driven into rotation by action of the radially oscillating balls. In another embodiment, the slotted intermediate disk is driven into rotation by action of the radially oscillating balls, with the drive force on the balls being reacted by the secondary cam as the grounded reaction disk. In another embodiment, one cam is grounded and is the reaction disk, while the second cam and the intermediate disk are the rotating input and output.
In various embodiments of the invention, the slot locations and the slot angles on the intermediate disk are selected in recognition of the fact that for a rotating primary cam, e.g., clockwise, the intermediate disk must locate the balls such that the rise side of the primary cam interacts with the clockwise side of the cycles of the secondary cam (for clockwise driven rotation) or with the counterclockwise side of the cycles of the secondary cam (for counterclockwise driven rotation). Thus the configuration of the intermediate disk is changed according to whether a reversing or non-reversing output is desired.
In one embodiment, the primary cam has a driving portion and the secondary cam has a driven portion, wherein the driving portion has a contour that varies substantially linearly with angular rotation at a first rate of variation. The driven portion varies substantially linearly with angular rotation at a second rate of variation. These cams are designed according to the cams developed in U.S. Pat. No. 5,312,306, incorporated herein by reference. Other waveforms, including those based on linear spiral segments and on sinusoidal curves, and others, can be used in practice of the present invention.
The relationship of the cams determines the speed conversion ratio of the apparatus. In accordance with the foregoing, the speed ratio of the apparatus can be determined by comparing the number of cycles of the output cam to the number of cycles of the input cam. Alternatively it can be a comparison of the number of slots to cycles, depending upon which component is input or output and which is reacting.
The primary and secondary cams are referred to as a conjugate pair, in that the centerline of a respective slot is defined as the straight-line loci of the interacting contact among the conjugate cams and the associated rolling element (e.g., ball).
In one embodiment of the invention, the first cam device is formed as a face cam on the primary cam disk, and in simplest form has one cycle starting at a base circle radius and proceeding about the center of the disk at a constantly increasing radius and at a constant angular rotation to a maximum radius at 180°, i.e., in the rise mode, and then proceeding in the fall mode at a decreasing radius of the same rate and constant angular rotation back to the original base circle radius, completing 360°. This symmetry achieves uniform speed output when the first cam is paired with a similarly symmetric second cam. A multiple-cycle cam may also be based on this design with a fractional period, i.e., 360°/(# of cycles).
In another embodiment of the invention, where the driven output rotates in the same direction as the drive input, and assuming a plurality of cycles in the secondary cam,
Bursal Faruk H.
Folino Frank A.
Maslow James E.
Cohen Jerry
Erlich Jacob N.
Perkins Smith & Cohen LLP
Synkinetics, Inc.
Ta Khoi Q.
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