Planetary reduction gear apparatus

• US 20100261571A1
• Filed: 10/09/2009
• Published: 10/14/2010
• Est. Priority Date: 04/17/2008
• Status: Active Grant

• Current Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Original Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Inventors: Matsuoka, Tetsuya, Nishikawa, Hiroyasu, Nishida, Tooru, Akahori, Hirofumi, Goi, Tatsuhiko
• Granted Patent: US 8,348,803 B2
• Time in Patent Office: Days
• US Class Current: 475/331
• CPC Class Codes: B64C 27/12 Rotor drives
• CPC Class Codes: F16H 1/2827 by allowing limited movement of the planet carrier, e.g. relative to its shaft
• CPC Class Codes: F16H 1/2836 by allowing limited movement of the planets relative to the planet carrier or by using free floating planets
• CPC Class Codes: F16H 1/48 Special means compensating for misalignment of axes , e.g. for equalising distribution of load on the face width of the teeth in combination with distribution of load on the planet-wheels F16H1/2809
• CPC Class Codes: F16H 57/082 Planet carriers

Abstract

This apparatus includes: a sun gear having external teeth; planetary gears, each having external teeth and configured to be meshed with the sun gear; planetary shafts, each being a rotation shaft of the planetary gear; a ring gear having internal teeth and configured to be meshed with the planetary gears; and a planetary carrier including an annular base plate and an annular back plate. The planetary carrier supports the planetary shafts between the annular base plate and the annular back plate and determines a relative position between planetary gears. The annular base plate is integrally formed with one end of the planetary shaft to support the one end. The annular back plate supports the other end of the planetary shaft. At least one of the planetary shaft and the planetary carrier has lower stiffness in its part adjacent to the one end of the planetary shaft than stiffness of its part adjacent to the other end thereof.

Claims

1. A planetary reduction gear apparatus comprising:

a sun gear having external teeth;

a plurality of planetary gears, each of the planetary gears having external teeth and being configured to be meshed with the sun gear;

a plurality of planetary shafts, each of the planetary shafts being a rotation shaft of each of the planetary gears;

a ring gear having internal teeth and configured to be meshed with the planetary gears; and

a planetary carrier including an annular base plate and an annular back plate, the planetary carrier being configured to support the planetary shafts between the annular base plate and the annular back plate and determine a relative position between planetary gears, the annular base plate being integrally formed with one end of the planetary shaft so as to support the one end, the annular back plate being configured to support an other end of the planetary shaft,

wherein at least one of the planetary shaft and the planetary carrier has a lower stiffness in its part adjacent to the one end of the planetary shaft than a stiffness of its part adjacent to the other end of the planetary shaft.

2. The planetary reduction gear apparatus according to claim 1, wherein an amount of material in the part of the planetary shaft or the planetary carrier adjacent to the one end of the planetary shaft is reduced.

3. The planetary reduction gear apparatus according to claim 2, wherein an axially extending through-hole is formed in the base plate.

4. The planetary reduction gear apparatus according to claim 3, wherein the base plate and the back plate are coupled with each other via an axially extending hollow carrier post, and wherein the axially extending through-hole is formed in a portion of the base plate facing a hollow portion of the carrier post.

5. The planetary reduction gear apparatus according to claim 2, wherein the planetary shaft is formed into a hollow shaft, and wherein a diametrically extending through-hole is provided at the part of the planetary shaft adjacent to the one end of the planetary shaft.

6. The planetary reduction gear apparatus according to claim 5, wherein the diametrically extending through-hole is formed so as to open in a radial direction with respect to an axis of the sun gear.

7. The planetary reduction gear apparatus according to claim 1, wherein a ratio Y1/Y2, which is defined as a ratio between a Young'"'"'s modulus Y1 in the part adjacent to the one end of the planetary shaft and a Young'"'"'s modulus Y2 in the part adjacent to the other end of the planetary shaft, is set within a range of 0.01 to 0.5.