Worm wheel, worm decelerator, and method for producing worm wheel

Patent metadata

Field	Value
Publication number	US-11047466-B1
Application number	US-201716074363-A
Country	US
Kind code	B1
Filing date	Jan 26, 2017
Priority date	Feb 2, 2016
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A first concave-convex part is formed in an outer diameter side circumferential surface of a first annular concave part provided in an axial one-side surface of an inner wheel element, and a second concave-convex part is formed in a bottom surface of a second annular concave part provided in the axial other-side surface of the inner wheel element. An outer circumferential part of the inner wheel element is embedded in an outer wheel element, and synthetic resin forming the outer wheel element partially enters into a plurality of concave parts constituting the first concave-convex part and the second concave-convex part. Thus, a configuration is achieved in which the holding power of a synthetic resin outer wheel can be secured from the metal inner wheel element, and the manufacturing error can be suppressed in the worm wheel tooth part provided in the outer circumferential surface of the outer wheel.

First claim

The invention claimed is:

1. A worm wheel comprising:
an inner wheel element; and
an outer wheel element, wherein:
the inner wheel element includes a first annular concave part provided to be recessed in an axial direction in an axial one-side surface, a second annular concave part provided to be recessed in the axial direction in an axial other-side surface, a first concave-convex part provided in an outer diameter side circumferential surface constituting an inner surface of the first annular concave part in a circumferential direction, and a second concave-convex part provided in an inner surface of the second annular concave part in a circumferential direction, and an outer circumferential surface thereof is formed to be a cylindrical surface part in which a diameter in the axial direction is not changed; and
the outer wheel element is made of a synthetic resin, has a worm wheel tooth part in an outer circumferential surface, and embeds the inner wheel element so as to cover a continuous range from a radial intermediate portion of a bottom surface constituting the inner surface of the first annular concave part, through an outer circumferential surface of the inner wheel element, to an inner diameter side circumferential surface constituting at least the inner surface of the second annular concave part in a surface of the inner wheel element over an entire circumference, the synthetic resin partially enters into a concave part constituting the first concave-convex part and a concave part constituting the second concave-convex part.

2. The worm wheel according to claim 1 , wherein
a tilted surface part which is tilted in a direction in which a width dimension in a radial direction of the second annular concave part becomes larger toward an axial other side with respect to a central axis of the inner wheel element is provided in at least one circumferential surface among an outer diameter side circumferential surface and the inner diameter side circumferential surface constituting the inner surface of the second annular concave part.

3. The worm wheel according to claim 2 , wherein
the tilted surface part and a non-tilted surface part which is not tilted with respect to the central axis of the inner wheel element are provided in the outer diameter side circumferential surface constituting the inner surface of the second annular concave part.

4. The worm wheel according to claim 2 , wherein
the tilted surface part and the non-tilted surface part which is not tilted with respect to the central axis of the inner wheel element are provided in the inner diameter side circumferential surface constituting the inner surface of the second annular concave part.

5. The worm wheel according to claim 1 , wherein
a projecting part which projects on the axial other side from a portion adjacent to the radially outer side is provided in a radially inner end part of the axial other-side surface of the outer wheel element.

6. The worm wheel according to claim 1 , wherein:
a sub concave part is provided to be recessed radially outward in a portion which is positioned on an axial deep side from an axial opening-side end edge of the first annular concave part in the outer diameter side circumferential surface constituting the inner surface of the first annular concave part; and
a portion of the synthetic resin constituting the outer wheel element enters into the sub concave part.

7. The worm wheel according to claim 6 , wherein
a cross section of the sub concave part with respect to a virtual plane including the central axis of the inner wheel element has a V shape such that a width dimension in the axial direction becomes smaller from an opening part on an inner diameter side toward a bottom part on an outer diameter side.

8. The worm wheel according to claim 1 , wherein
a plurality of teeth constituting the worm wheel tooth part are formed in a direction inclined in a predetermined direction with respect to the axial direction of the worm wheel, and a plurality of concave parts and convex part constituting the first concave-convex part are formed in a direction inclined in a direction opposite to the predetermined direction with respect to the axial direction of the worm wheel.

9. A worm reduction gear comprising:
a housing;
a rotation shaft which is supported to be rotatable with respect to the housing;
a worm wheel which has a worm wheel tooth part in an outer circumferential surface and is externally fitted and fixed to the rotation shaft; and
a worm shaft which has a worm tooth part in an axial intermediate portion of an outer circumferential surface and is supported to be rotatable with respect to the housing in a state where the worm tooth part is engaged with the worm wheel tooth part, wherein
the worm wheel is the worm wheel according to claim 1 .

10. The worm reduction gear according to claim 9 , wherein:
a rolling bearing which includes an inner ring, an outer ring, and a plurality of rolling bodies provided between an outer circumferential surface of the inner ring and an inner circumferential surface of the outer ring, and supports the rotation shaft to be rotatable with respect to the housing is provided in a portion adjacent to an axial other side of the worm wheel;
an axial other-side surface of the outer wheel element constituting the worm wheel faces an axial one-side surface of the inner ring and an axial one-side surface of the outer ring in the axial direction; and
an axial distance between the axial other-side surface of the outer wheel element and the axial one-side surface of the inner ring is smaller than an axial distance between the axial other-side surface of the outer wheel element and the axial one-side surface of the outer ring.

11. The worm reduction gear according to claim 10 , wherein:
a projecting part which projects on the axial other side from a portion adjacent to the radially outer side is provided in a radially inner end part of the axial other-side surface of the outer wheel element; and
an axial other-side surface of the projecting part faces the axial one-side surface of the inner ring in the axial direction.

12. A manufacturing method of the worm wheel according to claim 1 , the method comprising:
positioning a radially outer end part of a disc gate in the radially inner end part of the axial other side of the outer wheel element when an insertion molding is performed in which the outer wheel element is coupled with the inner wheel element at the same time when the outer wheel element is manufactured by an injection molding.

Assignees

• Nsk Ltd

Inventors

• Kiyota Haruhiko
• Yamamoto Takeshi
• Yasuda Kaname
• Arai Tomohiro
• Takano Junichi
• Hotta Kazuki

Classifications

• F16C19/36

  with a single row of rollers · CPC title

• B29K2705/00

  Use of metals, their alloys or their compounds, for preformed parts, e.g. for inserts · CPC title

• B29C45/1459

  Coating annular articles · CPC title

• F16H55/22 Primary

  for transmissions with crossing shafts, especially worms, worm-gears · CPC title

• F16H2055/065

  Moulded gears, e.g. inserts therefor · CPC title