Pure rolling cycloid transmissions with variable effective diameter rollers and roller constraints

Patent metadata

Field	Value
Publication number	US-11674564-B2
Application number	US-202017633790-A
Country	US
Kind code	B2
Filing date	Aug 26, 2020
Priority date	Aug 26, 2019
Publication date	Jun 13, 2023
Grant date	Jun 13, 2023

Abstract

A variety of transmissions, and improvements thereof, are provided having improved efficiency and other benefits. The transmissions include one or more inner members that are driven by one or more cams or other means to engage in precessional rotation about an axis of rotation that, itself, orbits about a primary axis of rotation. A plurality of shaped rollers are in contact with shaped cutouts on the inner member(s) and on a ground member such that an input rotation/torque applied via the cam is realized as an output rotation/torque at an output member that is coupled to the inner member(s). Tire rollers and contact surfaces are shaped such that the rollers engage in rolling motion relative to the contact surfaces, providing improved efficiency. Multiple inner members, and corresponding sets of shaped rollers, can be provided to increase power capacity, reduce torque ripple, reduce wobble, or provide other benefits.

First claim

What is claimed is:

1. A transmission comprising:
a sun gear;
an input member coupled to the sun gear such that rotation of the input member results in rotation of the sun gear;
two or more planet gears that are in geared contact with the sun gear;
two or more cams, each one of the two or more cams being coupled to a respective one of the two or more planet gears such that rotation of the sum gear results in rotation of each of the two or more cams;
an eccentric member that is coupled to the two or more cams such that rotation of the two or more cams results in eccentric motion of the eccentric member, wherein the eccentric member has two contact surfaces that define a series of variable-width cutouts;
a ground member that has at least two contact surfaces that define a series of variable-width cutouts;
an output member coupled to the eccentric member such that rotation of the eccentric member results in rotation of the output member; and
a plurality of rollers, each roller of the plurality of rollers being in contact with the contact surfaces of the eccentric member and the ground member such that rotation of the input member results in rotation of the eccentric member, whereby the rotation of the input member causes rotation of the output member.

2. The transmission of claim 1 , further comprising:
two or more additional cams, each one of the two or more additional cams being coupled to a respective one of the two or more planet gears such that rotation of the sun gear results in rotation of each of the two or more additional cams;
an additional eccentric member that is coupled to the two or more additional cams such that rotation of the two or more additional cams results in eccentric motion of the additional eccentric member, wherein the additional eccentric member has two contact surfaces that define a series of variable-width cutouts, and wherein the ground member has at least two additional contact surfaces that define an additional series of variable-width cutouts; and
a plurality of additional rollers, each roller of the plurality of additional rollers being in contact with the contact surfaces of the additional eccentric member and the at least two additional contact surfaces of the ground member such that rotation of the input member results in rotation of the additional eccentric member, whereby the rotation of the input member causes rotation of the output member.

3. The transmission of claim 2 , wherein a particular planet gear of the two or more planet gears is located between the cam of the two or more cams and the cam of the two or more additional cams to which the particular planet gear is coupled.

4. The transmission of claim 2 , wherein rotation of the input member causes the eccentric member and the additional eccentric member to engage in respective eccentric motions that are between 170 and 190 degrees out of phase.

5. The transmission of claim 4 , further comprising:
a plurality of mid-plane constraining elements, wherein a particular mid-plane constraining element of the plurality of mid-plane constraining elements substantially constrains, with respect to at least one degree of freedom, the location and rotation of a first particular roller of the plurality of rollers relative to a corresponding second particular roller of the plurality of additional rollers.

6. The transmission of claim 5 , wherein the particular mid-plane constraining element, the first particular roller, and the second particular roller are coupled together.

7. The transmission of claim 5 , wherein the particular mid-plane constraining element includes (i) a first constraining portion coupled to the first particular roller and (ii) a second constraining portion coupled to the second particular roller, the first and second constraining portion having respective shapes that constrain relative rotation between the first and second particular rollers about a first axis of rotation while permitting relative rotation between the first and second particular rollers about second and third axes of rotation that are orthogonal to the first axis and while also permitting relative translation between the first and second particular rollers.

8. The transmission of claim 5 , wherein the particular mid-plane constraining element includes a rod that is disposed within apertures in the first and second particular rollers such that the particular mid-plane constraining element constrains relative rotation between the first and second particular rollers about a first axis of rotation while permitting relative translation between the first and second particular rollers along the first axis of rotation.

9. The transmission of claim 5 , wherein the particular mid-plane constraining element includes a first roller and a second roller, wherein the first roller is in contact with an additional contact surface of the ground member and the second roller is in contact with an additional contact surface of the eccentric member such that that rotation of the input member results in the first roller and the second roller engaging in rolling motion in contact with the additional contact surface of the ground member and the additional contact surface of the eccentric member, respectively.

10. The transmission of claim 9 , wherein the particular mid-plane constraining element additionally includes a third roller that is in contact with an additional contact surface of the additional eccentric member such that that rotation of the input member results in the third roller engaging in rolling motion in contact with the additional contact surface of the additional eccentric member.

11. The transmission of claim 5 , further comprising a cage that is in contact with the plurality of mid-plane constraining elements so as to maintain the locations of the plurality of mid-plane constraining elements relative to each other.

12. The transmission of claim 11 , further comprising an additional cage that is in contact with the plurality of rollers so as to maintain the locations of the plurality of rollers relative to each other.

13. The transmission of claim 11 , wherein the particular mid-plane constraining element includes a first roller that is in contact with an additional contact surface of the ground member such that that rotation of the input member results in the first roller engaging in rolling motion in contact with the additional contact surface of the ground member.

14. The transmission of claim 5 , wherein the particular mid-plane constraining element is in geared contact with an additional contact surface of the ground member.

15. The transmission of claim 1 , wherein a particular roller of the plurality of rollers has at least two inward-facing contact surfaces that are in contact with the contact surfaces of the eccentric member.

16. The transmission of claim 1 , wherein the two or more planet gears, the two or more cams, and the eccentric member form a first sub-transmission, and wherein the transmission additionally comprises:
two or more additional sub-transmissions, each of the additional sub-transmissions including a respective additional eccentric member, additional two or more planet gears, and additional two or more cams.

17. The transmission of claim 16 , wherein rotation of the input member causes the eccentric member and the eccentric members of the additional sub-transmissions to engage in respective eccentric motions having phases that are substantially evenly separated.

18. The transmission of claim 1 , wherein each of the two or more cams is coupled to and rotates around a re

Assignees

• Stanford Res Inst Int

Inventors

• Kernbaum Alexander
• Kitchell Murphy

Classifications

• F16H2001/325

  comprising a carrier with pins guiding at least one orbital gear with circular holes · CPC title

• F16H2001/323

  comprising eccentric crankshafts driving or driven by a gearing · CPC title

• F16H13/08

  with balls or with rollers acting in a similar manner · CPC title

• F16H1/32 Primary

  in which the central axis of the gearing lies inside the periphery of an orbital gear · CPC title