Denso Corporation

Yukihiro Honda

Hiroshi Okada

Soichi Kinouchi

Takashi Furukawa

Akinori Kuwayama

Yukihiro Jo

Hiroaki Oe

An eccentric oscillating speed reducer includes an input rotor, a first rotor, a second rotor, a planetary rotor, a flow passage, a contact portion and a radial relief groove. The flow passage includes an axial gap located between the planetary rotor and a contact member. The flow passage conducts a lubricant oil that is forced to flow by a centrifugal force. The contact portion is placed in a drive force transmission path from the planetary rotor to the second rotor. The contact portion includes: a planetary rotor end surface of the planetary rotor located on a side where the second rotor is placed; and a second rotor end surface of the second rotor, which is opposed to the planetary rotor end surface. The radial relief groove forms a portion of the flow passage and extends through a radial width of the planetary rotor end surface.

Eccentric oscillating speed reducer

Each of an external tooth-bottom surface and an external bottom-side contact surface has a cross-sectional shape formed by a hypocycloid curved line. An external front-side contact surface has a cross-sectional shape formed by an epicycloid curved line. An external tooth-front surface is formed at a radial-inside position of a reference epicycloid curved line, that is, a position closer to a first pitch circle of an external gear. A possible contact between a tooth-front portion of the external gear and a tooth-front portion of an internal gear can be avoided. A connecting point between the external tooth-front surface and the external front-side contact surface is located at such a position that a contact surface length of an external tooth-contact surface is larger than twenty percent of a total tooth surface of the external gear.

Planetary gear train of internal engagement type

A second rotor and a third rotor are accommodated in a first rotor. A fitting portion of the third rotor is located in an engagement hole of the second rotor to engage the third rotor with the second rotor. The third rotor is rotational about an axis, which is eccentric to an axis of the first rotor, to vary a relative rotational phase of the first rotor to the second rotor and to accelerate and decelerate rotation of the second rotor. When friction arises between the second rotor and the fitting portion, a frictional force acts in a direction to reduce a rotational moment acting on the third rotor. A friction coefficient between the second rotor and the fitting portion is greater than a friction coefficient between ferrous objects.

Eccentric oscillating reduction gear device

An eccentric speed variator includes a first rotor, a second rotor, a third rotor, a cylindrical pin, and a flange. The second rotor has a hole formed therein. The third rotor rotates eccentrically to change a relative rotation phase between the first and second rotors. The cylindrical pin extends through the hole of the second rotor to establish mechanical engagement between the second and third rotors. The flange is secured to or integrally formed with an end of the cylindrical pin. In operation, when the flange contacts the outside wall of the second rotor, it serves to minimize inclination of the third rotor relative to the second rotor, thereby reducing local friction between the second and third rotors to eliminate undesirable mechanical vibration or noise. This structure also enables parts of the cycloidal speed reducer to be decreased, which leads to a reduced size of the cycloidal speed reducer.

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Kariya, Japan

Yukihiro Honda