Differential gear mechanism for vehicle
A differential gear mechanism includes a housing, first and second sun gears each including an external gear portion, and first and second planetary gears. The first and second sun gears include axial end surfaces pressed against contact surfaces provided at the housing by the first and second sun gears by means of thrust forces generated at engagement surfaces between the external gear portions and the planetary gears. Each of the sun gears includes a first portion having the external gear portion, a second portion, and a thrust force generating mechanism for generating thrust forces at the first portion and the second portion. A direction of the thrust force generated at the first portion by the thrust force generating mechanism is specified to be equal to a direction of the thrust force generated at the first portion by means of the engagement between the external gear portion and the planetary gear.
1. A differential gear mechanism for a vehicle, comprising:
a housing driven to rotate about a rotational axis and including contact surfaces;
first and second sun gears provided within the housing to be rotatable about the rotational axis, each of the first and second sun gears including an external gear portion at an outer periphery;
first and second planetary gears rotatably provided within the housing and engaging with the external gear portions of the sun gears respectively, the planetary gears engaging with each other;
the first and second sun gears including axial end surfaces respectively pressed against the contact surfaces of the housing by the first and second sun gears being pressed along the rotational axis by means of thrust forces generated at engagement surfaces between the external gear portions of the first and second sun gears and the first and second planetary gears respectively; and
each of the first and second sun gears including a first portion having the external gear portion, a second portion formed separately from the first portion, and a thrust force generating mechanism formed between the first portion and the second portion for generating thrust forces at the first portion and the second portion in a direction parallel with the rotational axis when a power transmission is performed between the first portion and the second portion, wherein a direction of the thrust force generated at the first portion by the thrust force generating mechanism is specified to be equal to a direction of the thrust force generated at the first portion by means of the engagement between each of the external gear portions and each of the first and second planetary gears.
2. A differential gear mechanism according to claim 1 , wherein the external gear portions and the first and second planetary gears include helical teeth respectively and the first and second plant gears are arranged in parallel with the rotational axis.
3. A differential gear mechanism according to claim 2 , wherein each of the thrust force generating mechanisms includes a spline bore formed at an inner periphery of the first portion and including helical teeth and a spline portion formed at an outer periphery of the second portion and engaging with the spline bore of the first portion, the first portion forming a cylindrical shape.
4. A differential gear mechanism according to claim 3 , wherein an outer diameter of the spline portion of one of the first and second sun gears is different from an outer diameter of the spline portion of the other one of the first and second sun gears.
5. A differential gear mechanism according to claim 3 , wherein a helical angle of the spline portion of one of the first and second sun gears is different from a helical angle of the spline portion of the other one of the first and second sun gears.