Drive transmission device and construction machine
A drive transmission device according to one embodiment of the disclosure includes a single differential unit to which rotation of a motor is transmitted and two speed reducers each having an operation output shaft that is coupled to the differential unit and a carrier that changes a speed of the rotation of the operation output shaft and outputs the rotation. The two speed reducers are arranged such that they are opposed to each other along a second rotation axis, and the operation output shaft and the carrier in each speed reducer are aligned in the second rotation axis direction.
1 . A drive transmission device, comprising:
a single transmission portion to which rotation of a drive source generating a rotational force is transmitted; and
two speed changers each having an input shaft and an output shaft, the input shaft being coupled to the transmission portion, the output shaft changing a speed of rotation of the input shaft and outputting a speed-changed rotation,
wherein the input shaft and the output shaft are aligned in a same rotation axis direction and the two speed changers are opposed each other in the rotation axis direction,
wherein the transmission portion is disposed between the two speed changers,
wherein the transmission portion includes a differential unit that includes a ring gear to which the rotation of the drive source is transmitted,
wherein the input shaft is coupled to a drive shaft of the differential unit,
wherein the drive transmission device further comprises an overload protection device that is disposed in a differential case of the differential unit and that connects the input shafts of the two speed changers, and
wherein the overload protection device allows rotations of the input shafts relatively to each other when a difference in torque between the input shafts exceeds a predetermined value.
2 . The drive transmission device of claim 1 , wherein the two speed changers each include at least one crankshaft that receives the rotation of the input shaft and rotates about another rotation axis parallel to the rotation axis direction,
wherein the two speed changers function as eccentric oscillating type speed changers, each of the eccentric oscillating type speed changers decelerating the rotation of the crankshaft and transmitting the decelerated rotation to the output shaft so that the output shaft is rotated at a reduced speed compared to the input shaft.
3 . The drive transmission device of claim 2 , wherein the crankshaft includes two or more crankshafts,
wherein the two speed changers each further include:
an external teeth member having external teeth that are oscillatory rotated about the rotation axis by the crankshafts; and
a casing having internal teeth that mesh with the external teeth,
wherein the output shaft rotatably supports the crankshafts and is rotatably supported by the casing via a bearing, and
wherein the output shaft is a carrier that is rotated relative to the casing at a reduced speed by the crankshafts.
4 . A construction machine, comprising:
a first member having a drive source that generates a rotational force; and
a second member coupled to the first member via a drive transmission device such that the second member is rotatable about a rotation axis,
wherein the drive transmission device includes:
a transmission portion to which a rotational force of the drive source is transmitted; and
two speed changers changing a speed of rotation of the transmission portion and outputting the rotation to the second member,
wherein the two speed changers each include an input shaft coupled to the transmission portion and an output shaft coupled to the second member,
wherein the input shaft and the output shaft are aligned along the rotation axis, and the two speed changers are opposed to each other in the rotation axis direction.