Automatic speed reducing ratio-switching apparatus

• US 7,510,495 B2
• Filed: 08/18/2006
• Issued: 03/31/2009
• Est. Priority Date: 08/29/2005
• Status: Expired due to Fees

• Current Assignee: SMC Kabushiki Kaisha
• Original Assignee: SMC Kabushiki Kaisha
• Inventors: Imamura, Masaki, Masui, Ryuichi, Saitoh, Akio, Nagai, Shigekazu
• Primary Examiner(s): Le; David D.
• Application Number:
  US11/465,490
• Publication Number:
  US 20070049453A1
• Time in Patent Office: 956 Days
• Field of Search: 475/85, 475/91, 475/112, 475/263, 475/266, 475/299, 475/344
• US Class Current: 475/91
• CPC Class Codes: F16H 3/54 one of the central gears being internally toothed and the other externally toothed
• CPC Class Codes: F16H 61/0295 Automatic gear shift control, e.g. initiating shift by centrifugal forces

Abstract

Helical gears, which are provided for a sun gear, planet gears, and an internal gear, have helix angles θ of not less than 25 degrees and not more than 45 degrees. Pawls provided for lock sections and internal gear lock receiving sections of the internal gear have rising angles γ, respectively, that satisfy the relational expression, 0 ≦tan γ<(η·di)/{dp·tan(90−α)}, wherein α is the helix angle of the sun gear, η is the screw efficiency of the sun gear as a sliding screw, dp is the pitch circle diameter of the sun gear, and di is an outer diameter of the internal gear defining a center of application of torque of the pawls.

Claims

1. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein a helix angle θ

of each of said helical gears making up said sun gear, said planet gears, and said internal gear, is not less than 25 degrees and not more than 45 degrees.

2. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein said brake mechanism includes lock sections provided in a housing that accommodates said planetary gear mechanism, and internal gear clutches disposed at circumferential edge portions of said internal gear, and

wherein a rising angle γ

of each of pawls of said lock sections and said internal gear clutches satisfies the relational expression

0≦

tan γ

<

(η

·

di)/{dp·

tan(90−

α

)}

in which

α

;

helix angle of said sun gear;

η

;

screw efficiency of said sun gear as a sliding screw;

dp;

pitch circle diameter of said sun gear; and

di;

outer diameter of said internal gear (center of application of torque of said pawls).

3. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein a first seal mechanism, which prevents said viscous resistance member from flowing out from said carrier, is provided in an annular groove of said carrier, and

wherein said first seal mechanism is composed of a pair of O-rings, and a deformation amount of said O-rings is not less than 0.5% and not more than 1.5% of a substantially circular vertical cross-sectional area thereof.

4. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein a second seal mechanism, which prevents said viscous resistance member from flowing out from said input shaft, is provided in an annular groove of said input shaft, and

wherein said second seal mechanism is composed of a ring having a substantially X-shaped cross section, and a deformation amount of said ring having said substantially X-shaped cross section is not less than 0.5% and not more than 1.5% of a vertical cross-sectional area thereof.

5. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein said brake mechanism includes lock receiving sections disposed at circumferential edge portions of said internal gear, and clutch mechanisms, each of which includes a cylindrical member that runs idly in only one direction between a first bearing disposed on an inner side and a second bearing disposed on an outer side, and lock sections that engage with said lock receiving sections of said internal gear, and

said lock sections are formed at circumferential edge portions of said cylindrical member in an axial direction thereof, and said clutch mechanisms, each of which has the same structure, are disposed respectively on a side of said input shaft and a side of said output shaft.

6. An automatic speed reducing ratio-switching apparatus comprising:

a planetary gear mechanism including an input shaft and an output shaft, said planetary gear mechanism further including a sun gear, planet gears, and an internal gear, each of which are helical gears, and a carrier that rotatably supports said planet gears and which is integrally rotated in accordance with revolution of said planet gears;

a viscous resistance member, which is provided within an inner section of said carrier internally inserted into said internal gear, said planet gears, and said internal gear, and which generates a thrust force between said internal gear and said planet gears; and

a brake mechanism that causes said internal gear to be displaced in parallel by said thrust force, in a direction toward said input shaft or a direction toward said output shaft, in accordance with increase or decrease in output load, in order to brake rotational motion of said internal gear,

wherein said carrier, which includes said inner section, is formed integrally with said output shaft.

7. The automatic speed reducing ratio-switching apparatus according to claim 6, wherein a plurality of grooves parallel to an axial direction are formed on an outer diameter surface of said inner section of said carrier.

8. The automatic speed reducing ratio-switching apparatus according to claim 6, wherein a plurality of annular grooves perpendicular to an axial direction and parallel to a circumferential direction are formed on an outer diameter surface of said inner section of said carrier.

9. The automatic speed reducing ratio-switching apparatus according to claim 6, wherein a plurality of inclined grooves intersecting an axial direction at a predetermined angle are disposed in alignment on an outer diameter surface of said inner section of said carrier.

10. The automatic speed reducing ratio-switching apparatus according to claim 6, wherein a plurality of dimples composed of recesses having semispherical cross sections are formed on an outer diameter surface of said inner section of said carrier.