Drive unit
A drive unit a drive unit which can prevent an occurrence of an unintentional relative rotation between the right and the left wheels is provided. The drive unit comprises: a first motor connected to the first driveshaft and a second motor connected to the second drive shaft; a first torque transmitting route between the first motor and the first drive shaft; a second torque transmitting route between the second motor and the second drive shaft; a first rotary member arranged in the first torque transmitting route; a second rotary member arranged in the second torque transmitting route; and a restriction device that restricts a differential rotation between the first rotary member and the second rotary member.
1. A drive unit, comprising:
a prime mover including a first motor having a first output shaft, and a second motor having a second output shaft;
a first driveshaft that transmits torque from the prime mover to one of first and second drive wheels; and
a second drive shaft that transmits torque from the prime mover to other of the first and second drive wheels,
wherein the first drive shaft and the second drive shaft are allowed to be rotated by different torques,
the drive unit comprising:
a first gear train including gears rotating around axes parallel to a rotational center axis of the first output shaft that is formed between the first output shaft and the first driveshaft;
a second gear train including gears rotating around axes parallel to a rotational center axis of the second output shaft that is formed between the second output shaft and the second driveshaft;
a first rotary member that is arranged in the first gear train,
a second rotary member that is arranged in the second gear train; and
a restriction device that is interposed between the first rotary member and the second rotary member to restrict a differential rotation between the first drive wheel and the second drive wheel by changing a torque transmitted between the first rotary member and the second rotary member.
2. The drive unit as claimed in claim 1 , further comprising:
a third rotary member arranged in the first gear train;
a fourth rotary member arranged in the second gear train; and
a lock device that stops rotation of any one of the third rotary member and the fourth rotary member.
3. The drive unit as claimed in claim 1 ,
wherein the restriction device includes a frictional engagement mechanism having a first rotary element rotated integrally with the first rotary member, a second rotary element rotated integrally with the second rotary member, and an actuator that selectively brings the second rotary element into contact to the first rotary element while controlling a contact pressure there between,
the first rotary element includes a first brake rotor,
the second rotary element includes a second brake rotor, and
the drive unit further comprising:
a first brake device that brings a first fixing member into contact to the first brake rotor to apply a braking torque to the first rotary element; and
a second braking device that brings a second fixing member into contact to the second brake rotor to apply a braking torque to the second rotary element.
4. The drive unit as claimed in claim 1 ,
wherein a rotational center axis of the first motor and a rotational center axis of the second motor are aligned coaxially with each other,
the first output shaft extends toward the second motor,
a first output gear is fitted onto a portion of the first output shaft extending toward the second motor,
the first gear train connects the first output gear to the first driveshaft,
the second output shaft extends toward the first motor,
a second output gear is fitted onto a portion of the second output shaft extending toward the first motor,
the second gear train connects the second output gear to the second driveshaft, and
the restriction device is interposed between laterally inner ends of the first output shaft and the second output shaft to change a torque transmitted between the first output shaft and the second output shaft.
5. The drive unit as claimed in claim 1 ,
wherein a rotational center axis of the first motor and a rotational center axis of the second motor are aligned coaxially with each other,
the first driveshaft is connected to the first gear train in such a manner that the rotational center axis of an end portion thereof is aligned coaxially with the rotational center axis of the first motor, and
the second driveshaft is connected to the second gear train in such a manner that the rotational center axis of an end portion thereof is aligned coaxially with the rotational center axis of the second motor.
6. The drive unit as claimed in claim 5 ,
wherein the first output shaft protrudes from both sides of the first motor,
a first planetary gear unit comprising a first sun gear, a first carrier and a first ring gear is arranged on a portion of the first output shaft protruding from the first motor in a direction opposite to the second motor,
the first driveshaft is connected to the first carrier, the first output shaft is connected to the first sun gear, and the first ring gear is fixed,
the first gear train includes the first planetary gear unit,
the second output shaft protrudes from both sides of the second motor,
a second planetary gear unit comprising a second sun gear, a second carrier and a second ring gear is arranged on a portion of the second output shaft protruding from the second motor in a direction opposite to the first motor,
the second driveshaft is connected to the second carrier, the second output shaft is connected to the second sun gear and the second ring gear is fixed,
the second gear train includes the second planetary gear unit, and
the restriction device is interposed between the portion of the first output shaft protruding from the first motor in a direction opposite to the second motor and the portion of the second output shaft protruding from the second motor in a direction opposite to the first motor, to change a torque transmitted between the first output shaft and the second output shaft.
7. The drive unit as claimed in claim 2 ,
wherein the restriction device includes a frictional engagement mechanism having a first rotary element rotated integrally with the first rotary member, a second rotary element rotated integrally with the second rotary member, and an actuator that selectively brings the second rotary element into contact to the first rotary element while controlling a contact pressure therebetween,
the first rotary element includes a first brake rotor,
the second rotary element includes a second brake rotor, and
the drive unit further comprising:
a first brake device that brings a first fixing member into contact to the first brake rotor to apply a braking torque to the first rotary element; and
a second braking device that brings a second fixing member into contact to the second brake rotor to apply a braking torque to the second rotary element.
8. The drive unit as claimed in claim 2 ,
wherein a rotational center axis of the first motor and a rotational center axis of the second motor are aligned coaxially with each other,
the first output shaft extends toward the second motor,
a first output gear is fitted onto a portion of the first output shaft extending toward the second motor,
the first gear train connects the first output gear to the first driveshaft,
the second output shaft extends toward the first motor,
a second output gear is fitted onto a portion of the second output shaft extending toward the first motor,
the second gear train connects the second output gear to the second driveshaft, and
the restriction device is interposed between laterally inner ends of the first output shaft and the second output shaft to change a torque transmitted between the first output shaft and the second output shaft.
9. The drive unit as claimed in claim 3 ,
wherein a rotational center axis of the first motor and a rotational center axis of the second motor are aligned coaxially with each other,
the first output shaft extends toward the second motor,
a first output gear is fitted onto a portion of the first output shaft extending toward the second motor,
the first gear train connects the first output gear to the first driveshaft
the second output shaft extends toward the first motor,
a second output gear is fitted onto a portion of the second output shaft extending toward the first motor,
the second gear train connects the second output gear to the second driveshaft, and
the restriction device is interposed between laterally inner ends of the first output shaft and the second output shaft to change a torque transmitted between the first output shaft and the second output shaft.
10. The drive unit as claimed in claim 7 ,
wherein a rotational center axis of the first motor and a rotational center axis of the second motor are aligned coaxially with each other,
the first output shaft extends toward the second motor,
a first output gear is fitted onto a portion of the first output shaft extending toward the second motor,
the first gear train connects the first output gear to the first driveshaft,
the second output shaft extends toward the first motor,
a second output gear is fitted onto a portion of the second output shaft extending toward the first motor,
the second gear train connects the second output gear to the second driveshaft, and
the restriction device is interposed between laterally inner ends of the first output shaft and the second output shaft to change a torque transmitted between the first output shaft and the second output shaft.