Rotational drive apparatus

Patent metadata

Field	Value
Publication number	US-9309806-B2
Application number	US-201414576612-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 27, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A first internal gear of a speed reducer includes an internally-toothed portion and a bearing portion and is formed as a one-piece member that is formed separately from a first housing. The internally-toothed portion forms internal teeth, which are meshed with external teeth of a first planetary gear. The bearing portion includes an eleventh cylindrical surface, which supports a motor shaft. The internal teeth of the first internal gear are arranged coaxial with the eleventh cylindrical surface. The internal teeth of the first internal gear and the bearing portion are formed as portions of the one-piece member.

First claim

What is claimed is:

1. A rotational drive apparatus comprising:
a first housing:
an electric motor that is received in the first housing;
a second housing that is fitted to the first housing and is fixed to the first housing;
an output shaft that is coaxial with a motor shaft of the electric motor and is rotatably supported by the second housing;
an eccentric shaft that is eccentric to the motor shaft and is rotatable integrally with the motor shaft;
a first internal gear that is coaxial with the motor shaft and is formed separately from the first housing and the second housing, wherein the first internal gear is entirely received in an inside of the first housing and is non-rotatably fitted to an inner wall surface of the first housing;
a first planetary gear that is meshed with the first internal gear from a radially inner side of the first internal gear, wherein the first planetary gear is rotatably supported by the eccentric shaft to enable rotation of the first planetary gear around the eccentric shaft, and at a time of rotating the motor shaft, the first planetary gear revolves around the motor shaft while changing a meshed location of the first planetary gear that is meshed with the first internal gear, and the first planetary gear is rotated about the eccentric shaft at a reduced speed that is reduced from a rotational speed of the motor shaft; and
a rotation transmitting device that transmits rotation of the first planetary gear, which is rotated about the eccentric shaft, to the output shaft, wherein:
the first internal gear is a one-piece member and is formed separately from the first housing, wherein the first internal gear includes:
an internally-toothed portion that is tubular and is fitted to the first housing, wherein the internally-toothed portion has a plurality of internal teeth that are meshed with a plurality of external teeth of the first planetary gear;
a bearing portion, which is configured into a tubular form and supports the motor shaft; and
a flange portion, which connects between the internally-toothed portion and the bearing portion.

2. The rotational drive apparatus according to claim 1 , wherein the rotation transmitting device further comprises:
a second planetary gear that is rotatably supported by the eccentric shaft to enable rotation of the second planetary gear about the eccentric shaft, wherein the second planetary gear is formed integrally and seamlessly with the first planetary gear; and
a second internal gear that is coaxial with the output shaft and is meshed with the second planetary gear from a radially outer side of the second planetary gear, wherein the second internal gear is rotatable integrally with the output shaft, and at a time of rotating the second planetary gear integrally with the first planetary gear about the eccentric shaft while revolving the second planetary gear about the motor shaft, the second internal gear rotates about the motor shaft at a reduced rotational speed that is reduced from a rotational speed of the second planetary gear, which is rotated about the eccentric shaft.

3. The rotational drive apparatus according to claim 2 , wherein the first internal gear, the first planetary gear, the second internal gear and the second planetary gear each include teeth and each tooth of the first internal gear, each tooth of the first planetary gear, each tooth of the second internal gear, and each tooth of the second planetary gear are configured into a trochoidal tooth shape.

4. The rotational drive apparatus according to claim 3 , wherein a difference between a number of the plurality of internal teeth of the first internal gear and a number of the plurality of external teeth of the first planetary gear is one.

5. The rotational drive apparatus according to claim 2 , wherein the second planetary gear is formed integrally and seamlessly with the first planetary gear as a one-piece member from fluorine resin or a material that contains the fluorine resin.

6. The rotational drive apparatus according to claim 1 , wherein:
the internally-toothed portion is axially displaced from the bearing portion;
the flange portion is placed on a radially outer side of the bearing portion and includes:
a tubular section that is connected to the internally-toothed portion; and
a bottom section that connects between an end part of the tubular section, which is opposite from the internally-toothed portion of the tubular section, and the bearing portion;

the tubular section of the flange portion includes a primary through-hole that radially extends through the tubular section; and
the bottom section of the flange portion includes a secondary through-hole that axially extends through the bottom section and receives a motor terminal of the electric motor.

7. The rotational drive apparatus according to claim 6 , wherein:
a direction, which is perpendicular to a rotational axis of the motor shaft, is defined as a perpendicular direction;
a direction, which is parallel to the perpendicular direction, is defined as a parallel direction;
the first housing includes a tertiary through-hole that extends through the first housing in the perpendicular direction or the parallel direction and is communicated with the primary through-hole of the first internal gear; and
the rotational drive apparatus further comprises a connector that includes a power terminal, which extends through the tertiary through-hole and the primary through-hole and is connected to the motor terminal while the connector is fixed to the first housing.

8. The rotational drive apparatus according to claim 7 , further comprising a rotational angle sensing device that is placed at a location, which axially coincides with a location of the rotation transmitting device and is radially displaced from the rotational axis, wherein the rotational angle sensing device senses a rotational angle of the output shaft.

9. The rotational drive apparatus according to claim 8 , wherein the rotational angle sensing device includes:
a first magnet that is magnetized in one direction, which is defined along a north pole and a south pole of the first magnet in parallel to an axial direction of the output shaft;
a second magnet that is magnetized in an opposite direction, which is defined along a north pole and a south pole of the second magnet in parallel to the axial direction of the output shaft and is opposite from the one direction, wherein the second magnet is placed at a location that is spaced from the first magnet in a rotational direction of the output shaft;
a first yoke that has an arcuate shape and extends in the rotational direction of the output shaft, wherein the first yoke between the north pole of the first magnet and the south pole of the second magnet;
a second yoke that has an arcuate shape and extends in the rotational direction of the output shaft, wherein the second yoke between the north pole of the second magnet and the south pole of the first magnet, and the second yoke cooperates with the first magnet, the second magnet, and the first yoke to form a closed magnetic circuit; and
a magnetism sensing device that is placed in a gap, which is formed between the first yoke and the second yoke and radially opens.

10. The rotational drive apparatus according to claim 9 , wherein the magnetism sensing device includes a magnetic flux density sensing element that outputs a signal, which corresponds to a density of a magnetic flux passing though the magnetic flux density sensing element.

11. The rotational drive apparatus according to claim 10 , wherein the rotational drive apparatus is a drive source of a waste gate valve apparatus.

12. The rotational dri

Assignees

• Denso Corp

Inventors

• Kuroda Tomonobu
• Yamanaka Tetsuji
• Kouno Naoaki

Classifications

• F16H2057/02082

  for application in vehicles other than propelling, e.g. adjustment of parts · CPC title

• F02B37/186 Primary

  Arrangements of actuators or linkage for bypass valves · CPC title

• F16H2001/325

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

• F16H1/32

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

• H02K7/116

  with gears · CPC title