Differential device

Patent metadata

Field	Value
Publication number	US-10190666-B2
Application number	US-201515319944-A
Country	US
Kind code	B2
Filing date	Jun 8, 2015
Priority date	Jun 24, 2014
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A differential device is provided in which a first wave number (Z1) of a first hypo groove part on an input plate, a second wave number (Z2) of a first epi groove part on a first differential plate and opposing the first hypo groove part, a third wave number (Z3) of a second hypo groove part on the first differential plate and on the opposite side from the first epi groove part, and a fourth wave number (Z4) of a second epi groove part on a second differential plate and opposing the second hypo groove part are set as Z1=8, Z2=Z3=6 and Z4=4, or as Z1=Z4=6, Z2=4, Z3=8. Such differential device enables equal torque distribution and equal differential rotation via a cycloid reduction mechanism without using a bevel gear or a center plate.

First claim

The invention claimed is:

1. A differential device that distributes rotational power of an input plate between a first output shaft and a second output shaft relatively rotatably arranged on a first rotational axis via a cycloid reduction mechanism or a trochoid reduction mechanism,
wherein the reduction mechanism comprises a first differential plate that is disposed so as to be adjacent to one side of the input plate rotating around the first rotational axis, a second differential plate that is disposed so as to be adjacent to one side, on the side opposite to the input plate, of the first differential plate, and an eccentric shaft that supports the first differential plate so as to be able to rotate around a second rotational axis that is eccentric from the first rotational axis, the eccentric shaft being connected to the first output shaft so as to be able to rotate as a unit, and the second differential plate being connected to the second output shaft so as to be able to rotate as a unit,
a first hypo groove part that extends in a peripheral direction along a hypocycloid curve or a hypotrochoid curve of a first wave number is formed in one side face, opposing the first differential plate, of the input plate, a first epi groove part that extends in the peripheral direction along an epicycloid curve or an epitrochoid curve of a second wave number is formed in one side face, opposing the input plate, of the first differential plate, a plurality of first rolling bodies are held between the first hypo groove part and the first epi groove part in an area where the first hypo groove part and the first epi groove part overlap one on another, a second hypo groove part that extends in the peripheral direction along a hypocycloid curve or a hypotrochoid curve of a third wave number is formed in the other side face, opposing the second differential plate, of the first differential plate, a second epi groove part that extends in the peripheral direction along an epicycloid curve or an epitrochoid curve of a fourth wave number is formed in one side face, opposing the first differential plate, of the second differential plate, a plurality of second rolling bodies are held between the second hypo groove part and the second epi groove part in an area where the second hypo groove part and the second epi groove part overlap one on another, and
the first wave number is 8, the second wave number and the third wave number are both 6, and the fourth wave number is 4, or the first wave number and the fourth wave number are both 6, the second wave number is 4, and the third wave number is 8.

2. The differential device according to claim 1 ,
wherein a differential case that is supported on a transmission case of an automobile so as to be able to rotate around the first rotational axis comprises the input plate and a cover that is fixed to the input plate and covers the first differential plate, the eccentric shaft, and the second differential plate.

3. The differential device according to claim 2 ,
wherein the eccentric shaft has a center shaft portion that rotates around the first rotational axis and an eccentric shaft portion that projects radially from the center shaft portion and supports the first differential plate so as to be able to rotate around the second rotational axis, the center shaft portion extends through a middle part of the input plate and is connected to the first output shaft, the second differential plate has a center shaft that rotates around the first rotational axis, and the center shaft extends through a middle part of the cover and is connected to the second output shaft.

4. The differential device according to claim 3 ,
wherein the input plate and the cover have hollow cylindrical first and second shafts that are rotatably supported on the transmission case on the first rotational axis, the center shaft portion of the eccentric shaft is rotatably supported on an inner periphery of the first shaft via a first bearing, the center shaft of the second differential plate is rotatably supported on an inner periphery of the second shaft via a second bearing, and the center shaft portion of the eccentric shaft on a side opposite to the first shaft is fitted via a third bearing into a circular recess portion formed in said one side face of the second differential plate.

5. The differential device according to claim 1 ,
wherein a cutout portion is formed in a middle part of said one side face of the input plate.

6. The differential device according to claim 1 ,
wherein a cutout portion is formed in a middle part of said one side face of the input plate, and a balancer that is linked to the eccentric shaft is disposed within the cutout portion so that the balancer rotates around the first rotational axis with a phase that is displaced by 180 degrees from a phase of a center of gravity of the first differential plate rotating around the first rotational axis.

7. The differential device according to claim 6 , wherein when a mass of the first differential plate is M1, a mass of the balancer is M2, a distance from the first rotational axis to the center of gravity of the first differential plate when viewed on a projection plane orthogonal to the first rotational axis is e1, and a distance from the first rotational axis to the center of gravity of the balancer is e2,
| M 1× e 1− M 2× e 2|< M 1× e 1/100

is satisfied.

8. The differential device according to claim 6 , wherein the eccentric shaft has a center shaft portion that rotates around the first rotational axis and an eccentric shaft portion that projects radially from the center shaft portion and supports the first differential plate so as to be able to rotate around the second rotational axis, the balancer has an arm portion that extends radially outwardly from an outer periphery of the center shaft portion in a direction that is opposite to a direction in which the eccentric shaft portion projects, and a weight portion that is connected to an extremity of the arm portion, and an outer periphery of the weight portion is formed into an arc shape along an inner periphery of the cutout portion.

9. The differential device according to claim 8 , wherein the balancer is formed integrally with the center shaft portion.

10. The differential device according to claim 6 , wherein a differential case that is supported on a transmission case of an automobile so as to be able to rotate around the first rotational axis comprises the input plate and a cover that is fixed to the input plate and covers the first differential plate, the eccentric shaft, the balancer and the second differential plate.

11. The differential device according to claim 6 , wherein a cylindrical auxiliary cutout portion that opposes the cutout portion of the input plate with the first differential plate sandwiched therebetween is formed in a middle part of said one side face of the second differential plate, and an auxiliary balancer is disposed within the auxiliary cutout portion, the auxiliary balancer being linked to the eccentric shaft so as to rotate around the first rotational axis with the phase that is displaced by 180 degrees from the phase of the center of gravity of the first differential plate rotating around the first rotational axis.

12. The differential device according to claim 1 ,
wherein the first differential plate is formed so as to include a pair of rotating plates that are linked to each other and can rotate as a unit.

13. The differential device according to claim 7 , wherein the eccentric shaft has a center shaft portion that rotates around the first rotational axis and an eccentric shaft portion that projects radially f

Assignees

• Musashi Seimitsu Kogyo Kk

Inventors

• Noguchi Takanori
• Hamada Tetsuro
• Sakata Shohei

Classifications

• F16H48/14 Primary

  with cams · CPC title

• F16H48/05

  Multiple interconnected differential sets · CPC title

• F16H57/037

  Gearboxes for accommodating differential gearings (rotating cases for differential gearings F16H48/40) · CPC title