Loading cam device and friction roller-type speed reducer

Patent metadata

Field	Value
Publication number	US-10167932-B2
Application number	US-201415514285-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Sep 26, 2014
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

Projections protruding towards a cam plate and a disc are provided on both axial side surfaces of the retainer at a plurality of positions at which phases of the projections in the circumferential direction are offset from pockets. One axial direction surface of the cam plate and the disc are formed with concave portions at portions facing the respective projections. The concave portions have an axial depth deepest at a center portion thereof in the circumferential direction and becoming shallower towards both end portions thereof.

First claim

The invention claimed is:

1. A loading cam device comprising:
a circular plate-shaped cam plate including one axial side surface which is a first cam surface having concaves and convexes in a circumferential direction;
a disc including one axial side surface which faces the first cam surface and is a second cam surface having concaves and convexes in a circumferential direction;
a circular ring-shaped retainer provided between the first cam surface and the second cam surface; and
a plurality of balls provided to contact the first and second cam surfaces at each rolling surface thereof while being rollably held in the retainer,
wherein projections protruding towards the cam plate and the disc are provided on both axial side surfaces of the retainer at a plurality of positions at which phases of the projections in the circumferential direction are offset from pockets for holding the respective balls, and one axial surfaces of the cam plate and the disc are formed with concave portions at portions facing the respective projections, the concave portions having an axial depth deepest at a center portion thereof in the circumferential direction and becoming shallower towards both end portions thereof in the circumferential direction.

2. The loading cam device according to claim 1 ,
wherein the projections are formed at portions at which the phases in the circumferential direction are middle portions between the pockets adjacent to each other.

3. The loading cam device according to claim 1 ,
wherein when an inclination angle of the both end portions of each concave portion in the circumferential direction is denoted as θ, a distance between a center axis of the retainer and a radially center portion of each concave portion is denoted as R, an inclination angle of each of the first and second cam surfaces is denoted as ϕ, and a distance between a center axis of each of the disc and the cam plate and a radially center portion of each of the first and second cam surfaces is denoted as r, a relation of R ·tan θ=r·tan ϕis satisfied.

4. The loading cam device according to claim 1 ,
wherein an axial height of the projections is larger than a half of a difference between a maximum value and a minimum value of an axial thickness of a gap between the cam plate and the disc.

5. A friction roller-type speed reducer comprising:
an input shaft; an output shaft; a sun roller; an annular roller; a plurality of intermediate rollers; and a loading cam device,
wherein the sun roller includes a pair of sun roller elements axially spaced and arranged concentrically with each other around the input shaft with a gap being interposed between tip surfaces thereof, outer peripheral surfaces of the sun roller elements are configured as inclined surfaces inclined in a direction along which outer diameters gradually decrease towards the tip surfaces thereof, and the inclined surfaces are configured as rolling contact surfaces,
wherein the annular roller is arranged concentrically with the sun roller around the sun roller, and an inner peripheral surface thereof is configured as a rolling contact surface,
wherein outer peripheral surfaces of the intermediate rollers are configured to contact outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller at a state where the intermediate rollers are supported at a plurality of positions in a circumferential direction in an annular space between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller so as to be freely rotatable about rotation axes arranged in parallel with the input shaft,
wherein the loading cam device is provided between a disc which is at least one of the sun roller elements and is configured to be rotatable relative to the input shaft, and a cam plate supported to the input shaft so as to be rotatable synchronously with the input shaft, and is configured to rotate the disc while axially pressing the disc towards the other of the sun roller elements as the input shaft rotates,
wherein one member of the annular roller and a member configured to support each of the rotation axes is prohibited from rotating about the sun roller and the other member is coupled to the output shaft such that the output shaft is configured to be rotated by the other member, and wherein the loading cam device is the loading cam device according to claim 1 .

6. A friction roller-type speed reducer comprising:
an input shaft; an output shaft; a sun roller; an annular roller; a plurality of intermediate rollers; and a loading cam device,
wherein the sun roller includes a pair of sun roller elements axially spaced and arranged concentrically with each other around the input shaft with a gap being interposed between tip surfaces thereof, outer peripheral surfaces of the sun roller elements are configured as inclined surfaces inclined in a direction along which outer diameters gradually decrease towards the tip surfaces thereof, and the inclined surfaces are configured as rolling contact surfaces,
wherein the annular roller is arranged concentrically with the sun roller around the sun roller, and an inner peripheral surface thereof is configured as a rolling contact surface,
wherein outer peripheral surfaces of the intermediate rollers are configured to contact outer peripheral surfaces of the sun roller and the inner peripheral surface of the annular roller at a state where the intermediate rollers are supported at a plurality of positions in a circumferential direction in an annular space between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller so as to be freely rotatable about rotation axes arranged in parallel with the input shaft,
wherein the loading cam device is provided between a moveable sun roller element which is at least one of the sun roller elements and is configured to be rotatable relative to the input shaft, and a cam plate supported to the input shaft so as to be rotatable synchronously with the input shaft, is configured to rotate the moveable sun roller element while axially pressing the movable sun roller element towards the other of the sun roller element as the input shaft rotates, and is configured by interposing rolling elements between a driven-side cam surface provided at a plurality of positions in a circumferential direction of a base end surface of the moveable sun roller element and a driving-side cam surface provided at a plurality of positions in the circumferential direction of one side surface, which faces the base end surface of the moveable sun roller element, of the cam plate fixed to a part of the input shaft and configured to rotate together with the input shaft, and the driving-side cam surface and the driven-side cam surface having a shape where an axial depth gradually changes in the circumferential direction and becomes shallower towards an end portion, respectively,
wherein one member of the annular roller and a member configured to support each of the rotation axes is prohibited from rotating about the sun roller and the other member is coupled to the output shaft such that the output shaft is configured to be rotated by the other member, and
wherein a hydraulic chamber is provided between the moveable sun roller element and the cam plate, the hydraulic chamber is configured to increase a hydraulic pressure therein based on a centrifugal force which is to be generated as the input shaft rotates, and an axial pressing force which is to be generated by the loading cam device is a summed force of a force which is to be generated as each rolling element overrides the driving-side cam surface and the driven-side cam surface and a force which is to be generated as the hydraulic pressure increases.

Assignees

• Nsk Ltd

Inventors

• Yoshioka Hiroyasu
• Inoue Eiji
• Imanishi Takashi
• Kishida Hirotaka

Classifications

• F16H25/186

  with reciprocation along the axis of oscillation · CPC title

• F16H13/06 Primary

  with members having orbital motion · CPC title

• F16H13/14

  for automatically varying the pressure mechanically · CPC title

• F16H13/08

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

• F16H57/08

  of gearings with members having orbital motion · CPC title