Planetary gear transmission systems or components – Planet pinion is friction gear – Planet pinion is ball
Reexamination Certificate
1999-03-29
2002-05-07
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Planet pinion is friction gear
Planet pinion is ball
C476S036000
Reexamination Certificate
active
06383110
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to mechanical power transmissions, and more particularly, to speed reducers and the like.
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 translating 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 synchronization, and are quite labor intensive for both assembly and service. Other speed conversion applications include elevators, where an electric motor typically is employed for lifting and lowering the elevator cab, and robotics, where an electric motor is employed as an actuator to effect motion. Typically in these applications, the speed reducer housing is mounted (“grounded”) directly to the equipment housing. At times the effect of speed reduction is also referred to as torque amplification, and these concepts may be treated as interchangeable, for purposes of this disclosure.
It is therefore 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 a variety of situations.
SUMMARY OF THE INVENTION
These and other objects are well met by the presently disclosed nested speed converting transmission. In one aspect of the invention, rotary motion is translated from a first speed at the input, such as from a motor, to a second speed at the load, using a nested set: including a pair of wavy devices, a slotted device between the pair, and an oscillatable translating arrangement, preferably using ball or roller type translating elements loaded in the slots of the slotted device. In a preferred embodiment of the invention, two of the devices are rotatable about a common axis with the third device fixed about that axis. In an alternative embodiment, the third device is also rotatable about the same axis.
For ease of description, the cam devices described herein may also be referred to as gears or cam-gears and the cam cycles may be referred to as teeth or cam-gear teeth, all interchangeably and without limitation. A device with two gears, a slotted part and interacting elements is described herein, also more generally referred to as three disks and interacting elements. These interacting elements may be balls, rollers, pins, bushings, ball bearing assemblies, or the like, or any combination thereof, and such terms may be used interchangeably herein. The terms drive and driven may be applied to various ones of the three disks, depending upon an application.
The invention is applicable to an accelerating or decelerating input, whether clockwise or counter-clockwise rotating, with reversing or non-reversing output, backdriveable or non-backdriveable.
A preferred embodiment includes a speed converter apparatus for translating an input at a first velocity to an output at a second velocity. The speed converter has a primary drive disk defining a primary cam (a “drive” cam) for providing a rotary motion input at a first angular velocity.
The speed converter apparatus also includes a driven assembly. The driven assembly has a secondary cam on a secondary disk, and an intermediate disk element. The intermediate disk is a directional element, located between the primary and secondary disks. The intermediate disk has slots for receipt of transmission elements (balls) therein. The speed converter output is taken from a driven disk, which is either the intermediate disk or the secondary disk.
In various embodiments, the primary and secondary cams are each formed on a face of a respective primary and secondary disk, and the slots are formed as radial slot paths in the intermediate disk. Each of the primary and secondary cams has a respective flank. Projections of these flanks intersect at unique points upon rotation of the primary cam, associated ones of these unique points defining respective ones of the slot paths in the intermediate disk.
A respective ball in a respective slot path is driven radially between a maximum and minimum radius by the primary cam. In one embodiment, the slotted intermediate disk is a reaction disk for reacting the drive force on the balls in the slots, and the secondary cam is driven into rotation by action of the oscillating balls. In another embodiment, the slotted intermediate disk is driven into rotation by action of the oscillating balls, with the drive force on the balls being reacted by the secondary cam, where the secondary disk is a reaction disk.
Overall, the primary cam is designed to cause a linear displacement of the balls for a given cam rotation. The secondary cam is configured for conjugate action with the primary cam, and which results in constant linear velocity of the radially traveling balls. The primary and secondary cams are thus referred to as a conjugate pair. The centerline of a respective slot is defined as the loci of the contact of the cams at the slots' given angular location.
In one embodiment, the primary cam contour varies substantially linearly with angular rotation at a first rate of variation. The secondary cam contour varies substantially linearly with angular rotation at a second rate of variation. The relationship of these variations 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 secondary cam to the number of cycles of the primary cam.
In this 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 lobe (or 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°.
The second cam device is formed as a multi-cycle face cam track on a second cam disk, and is mounted in a position facing the face cam track of the primary cam disk. Each cycle of this face cam track defines a rise mode and a fall mode. Each rise and fall mode of the plurality of cycles in the secondary cam are configured to have the same radial displacement, for uniform conversion during the main drive segment of the cams.
In a preferred embodiment of the invention, the ends of the cam segments that are modified for easing the transition of the balls changes the rate of ball travel in a controlled deceleration or acceleration.
A multi-stage drive with a through way for wire bundle run through the drive mechanism's center is also disclosed.
In one embodiment of the invention, the first of the wavy pair of devices, and preferably a conjugate pair of devices, is coupled to an input of the translation arrangement and the second of the pair is coupled to an output of the translation arrangement, such that motion of the first of the devices can be translated to motion of the second of the devices by the translation arrangement, with the slotted device being part of the translating arrangement.
In one embodiment, the conjugate pair includes a drive cam gear and a driven cam gear. A first one of the cam-gears has at least one tooth and a second one of the cam-gears has at least one additional tooth. The translation arrangement has a slotted disk with at least one radially extending slot for interaction with an interacting element (such as a
Cohen Jerry
Erlich Jacob N.
Marmor Charles A
Parekh Ankur
Perkins Smith & Cohen LLP
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