Deceleration device and seat drive device
A deceleration device comprising first and second gears that have different numbers of teeth. A cam mechanism is disposed on the same axis as the first gear, engages the first gear with the second gear in a state of eccentricity. A connecting shaft is disposed on the same axis as the first gear and is connected to the cam mechanism. A rotating body is disposed on the same axis as the second gear and is connected to the connecting shaft. When the connecting shaft is inserted into a long hole of the rotating body, the rotating body is connected to the connecting shaft in an eccentric position. The major axis of the long hole is set so as to allow the rotating body and the connecting shaft to move relative to one another along the longitudinal direction of the long hole.
1. A deceleration device comprising:
a first gear including either one of inner teeth and outer teeth and having a first number of teeth;
a second gear including the other one of the inner teeth and the outer teeth and having a second number of teeth, which differs from the first number of teeth;
a cam mechanism that is arranged coaxially with the first gear and rotationally supported by the first gear, wherein the cam mechanism is configured to cause the first gear to be engaged with the second gear in an eccentric state and receive drive torque to move a position where the first gear and the second gear are engaged;
a coupling shaft that is arranged coaxially with the first gear and coupled to the cam mechanism; and
a rotor that is arranged coaxially with the second gear and coupled to the coupling shaft, wherein the rotor is configured to enable the drive torque to be received by the cam mechanism through the coupling shaft, wherein
the rotor includes a first elongated hole that extends in a radial direction through a rotation center and is configured to allow the coupling shaft to be inserted into the first elongated hole, and when the coupling shaft is inserted into the first elongated hole, the rotor is coupled to the coupling shaft at an eccentric position corresponding to an eccentricity amount that is set between the first gear and the second gear, and
the first elongated hole has a major axis set to allow relative movement of the rotor and the coupling shaft in a longitudinal direction of the first elongated hole.
2. The deceleration device according to claim 1 , wherein
the rotor includes an insertion body that is movable in the first elongated hole in the longitudinal direction, and
the rotor is configured to be coupled to the coupling shaft by the insertion body.
3. The deceleration device according to claim 2 , wherein
the insertion body includes a second elongated hole that extends in a direction intersecting the longitudinal direction of the first elongated hole, and
the coupling shaft is configured to be inserted into the second elongated hole and be movable relative to the second elongated hole in a longitudinal direction of the second elongated hole.
4. The deceleration device according to claim 1 , wherein the cam mechanism includes:
a cam member surrounded by a circumferential wall that is arranged coaxially with the second gear and is arranged integrally with the second gear;
two pressing members located between the cam member and the circumferential wall; and
a spring member that biases the two pressing members in a direction that separates the two pressing members from each other and presses the two pressing members against the circumferential wall.
5. The deceleration device according to claim 1 , wherein the coupling shaft includes a double-plane portion including two parallel flat surfaces.
6. The deceleration device according to claim 5 , wherein a major axis of the first elongated hole is larger than a longitudinal length in a cross section of the double-plane portion.
7. A seat drive device comprising the deceleration device according to claim 1 located between two seat members.
8. The seat drive device according to claim 7 , wherein
the first gear is fixed to a first seat member of the two seat members, and
the second gear is fixed to a second seat member in a non-rotatable manner.
9. The seat drive device according to claim 8 , further comprising a support that is fixed to the second seat member and arranged coaxially with the second gear to rotationally support the rotor.