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EP-4386231-B1 - ECCENTRIC OSCILLATION TYPE SPEED REDUCER

EP4386231B1EP 4386231 B1EP4386231 B1EP 4386231B1EP-4386231-B1

Inventors

  • SHIROUZU, KENJI

Dates

Publication Date
20260506
Application Date
20231030

Claims (5)

  1. An eccentric oscillation type speed reducer (10) comprising: an eccentric body (12); an external gear (16) that is made to oscillate by the eccentric body (12); an internal gear (18) that meshes with the external gear (16); an eccentric bearing (20) that is disposed between the eccentric body (12) and the external gear (16); and a pin body (22) that is synchronized with an axial rotation component of the external gear (16), wherein the external gear (16) includes a pin hole (32) which is provided to be offset from a center (C16) of the external gear (16) in a radial direction and into which the pin body (22) is inserted, characterized in that in a case where an internal clearance of the eccentric bearing (20) in the radial direction is referred to as an eccentric bearing clearance X1 and a clearance between the pin body (22) and the pin hole (32) in an anti-maximum eccentric direction (Db) from an axial center (C22) of the pin body (22) in a case where the axial center (C22) of the pin body (22) is in a maximum eccentric direction (Da) is referred to as a pin hole clearance X2, the pin hole clearance X2 is negative and the following expression (1) is satisfied, eccentric bearing clearance X1 + pin hole clearance X2 > 0
  2. The eccentric oscillation type speed reducer (10) according to claim 1, wherein in a case where a clearance between the external gear (16) and the internal gear (18) in the maximum eccentric direction (Da) is referred to as an inter-tooth clearance X3, the inter-tooth clearance X3 is negative and the following expression (2) is satisfied, eccentric bearing clearance X1 + inter-tooth clearance X3 > 0
  3. The eccentric oscillation type speed reducer (10) according to claim 1 or 2, wherein in a case where a clearance between the external gear (16) and the internal gear (18) in the maximum eccentric direction (Da) is referred to as an inter-tooth clearance X3, the inter-tooth clearance X3 is definitely larger than the pin hole clearance X2.
  4. An eccentric oscillation type speed reducer (10) comprising: an eccentric body (12); an external gear (16) that is made to oscillate by the eccentric body (12); an internal gear (18) that meshes with the external gear (16); an eccentric bearing (20) that is disposed between the eccentric body (12) and the external gear (16); and a pin body (22) that is synchronized with an axial rotation component of the external gear (16), wherein the external gear (16) includes a pin hole (32) which is provided to be offset from a center (C16) of the external gear (16) in a radial direction and into which the pin body (22) is inserted, characterized in that in a case where an internal clearance of the eccentric bearing (20) in a maximum eccentric direction (Da) is referred to as an eccentric bearing clearance X1 and a clearance between the external gear (16) and the internal gear (18) in the maximum eccentric direction (Da) is referred to as an inter-tooth clearance X3, the inter-tooth clearance X3 is negative and the following expression (2) is satisfied, eccentric bearing clearance X1 + inter-tooth clearance X3 > 0
  5. The eccentric oscillation type speed reducer (10) according to claim 4, wherein in a case where a clearance between the pin body (22) and the pin hole (32) in an anti-maximum eccentric direction (Db) from an axial center (C22) of the pin body (22) in a case where the axial center (C22) of the pin body (22) is in the maximum eccentric direction (Da) is referred to as a pin hole clearance X2, the inter-tooth clearance X3 is definitely larger than the pin hole clearance X2.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an eccentric oscillation type speed reducer. Description of Related Art Japanese Unexamined Patent Publication No. 2022-82891 discloses an eccentric oscillation type speed reducer including an eccentric body, an external gear that is made to oscillate by the eccentric body, an internal gear that meshes with the external gear, an eccentric bearing that is disposed between the external gear and the eccentric body, and a pin body that is synchronized with an axial rotation component of the external gear. SUMMARY OF THE INVENTION In a case where the speed reducer is used for use requiring high positioning accuracy, the low lost motion of the speed reducer is required. The inventor has found that there is a problem in that it is difficult to achieve both a low lost motion and a low mechanical loss since a mechanical loss may be increased in a case where a lost motion is set to be low in the eccentric oscillation type speed reducer. An object of the present invention is to provide an eccentric oscillation type speed reducer in which an increase in mechanical loss can be suppressed while a lost motion is reduced. An eccentric oscillation type speed reducer according to a certain aspect of the present invention includes an eccentric body, an external gear that is made to oscillate by the eccentric body, an internal gear that meshes with the external gear, an eccentric bearing that is disposed between the eccentric body and the external gear, and a pin body that is synchronized with an axial rotation component of the external gear. The external gear includes a pin hole which is provided to be offset from a center of the external gear in a radial direction and into which the pin body is inserted. In a case where an internal clearance of the eccentric bearing in the radial direction is referred to as an eccentric bearing clearance X1 and a clearance between the pin body and the pin hole in an anti-maximum eccentric direction from an axial center of the pin body in a case where the axial center of the pin body is in a maximum eccentric direction is referred to as a pin hole clearance X2, the pin hole clearance X2 is negative and the following expression (1) is satisfied. Eccentric bearing clearance X1 + pin hole clearance X2 > 0 An eccentric oscillation type speed reducer according to another aspect of the present invention includes an eccentric body, an external gear that is made to oscillate by the eccentric body, an internal gear that meshes with the external gear, an eccentric bearing that is disposed between the eccentric body and the external gear, and a pin body that is synchronized with an axial rotation component of the external gear. The external gear includes a pin hole which is provided to be offset from a center of the external gear in a radial direction and into which the pin body is inserted. In a case where an internal clearance of the eccentric bearing in a maximum eccentric direction is referred to as an eccentric bearing clearance X1 and a clearance between the external gear and the internal gear in the maximum eccentric direction is referred to as an inter-tooth clearance X3, the inter-tooth clearance X3 is negative and the following expression (2) is satisfied. Eccentric bearing clearance X1 + inter-tooth clearance X3 > 0 According to the present invention, it is possible to provide an eccentric oscillation type speed reducer in which an increase in mechanical loss can be suppressed while a lost motion is reduced. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side cross-sectional view of an eccentric oscillation type speed reducer according to an embodiment.Fig. 2 is a partial cross-sectional view of the eccentric oscillation type speed reducer according to the embodiment as viewed in an axial direction.Fig. 3 is a diagram illustrating an inter-tooth clearance.Fig. 4 is a diagram relating to Expression (1).Fig. 5 is a diagram relating to Expression (2). DETAILED DESCRIPTION OF THE INVENTION A speed reducer according to an embodiment of the present invention will be described below. The same or equivalent components will be denoted by the same reference numerals and the repeated description thereof will be omitted. In each drawing, for the convenience of description, components will be omitted, enlarged, or reduced as appropriate. The drawings should be viewed according to the direction of a reference numeral. First, a background leading to an idea of the speed reducer according to the present embodiment will be described. In order to achieve the low lost motion of a speed reducer, attention may be paid to a clearance (hereinafter, referred to as a component clearance) between a movable component of the speed reducer and another component affecting the lost motion and the component clearances may be reduced. The inventor has found that a mechanical loss is increased in the eccentric oscillation type speed reducer in