Central differential for a four-wheel drive motor vehicle

• US 4,969,532 A
• Filed: 10/27/1988
• Issued: 11/13/1990
• Est. Priority Date: 11/04/1987
• Status: Expired due to Fees

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Oyama, Fusami, Inoue, Takeo
• Primary Examiner(s): Hill, Mitchell J.
• Application Number:
  US07/263,637
• Time in Patent Office: 747 Days
• Field of Search: 180/233, 180/248, 180/249, 74/695, 74/700, 74/701, 74/713, 74/711, 475/198, 475/230, 475/330
• US Class Current: 180/233
• CPC Class Codes: B60K 17/346 the transfer gear being a differential gear

Abstract

A central differential for a four-wheel drive motor vehicle is provided on a pair of axles for right and left drive wheels. The differential has a tubular member secured to a final gear of a transmission, a pair of carriers one of which is connected to the drive wheels and the other carrier is operatively connected to the other drive wheels. A pair of annular side gears are securely provided on the tubular member, and an annular center gear rotatably mounted on the tubular member between the side gears. A pair of planetary gears are rotatably supported in the corresponding carrier. Each planetary gear comprises a pair of planet pinions, one of which is engaged with the side gear and the other is engaged with the center gear.

Claims

1. In a differential system for a four-wheel drive motor vehicle having a first differential for differentiating front and rear wheels of the vehicle, a second differential operatively connected to a pair of axles for differentiating right and left wheels of a set of drive wheels of the motor vehicle, and a final gear transmitting power from a transmission, the improvement wherein the first differential comprises:

a tubular body rotatably supported around one of said pair of axles and operatively connected to the final gear;

a first carrier secured to a differential case of the second differential;

a second carrier rotatably supported on the tubular body and operatively connected to another set of drive wheels of the motor vehicle;

a pair of side gears forms on the tubular body;

a center gear having a pair of gears and rotatably mounted on the tubular body;

a first planet gear having a pair of planet pinions and rotatably supported on the first carrier;

a second planet gear having a pair of planet pinions and rotatably supported on the second carrier;

one of said pair of planet pinions of the first planet gear being engaged with one of the said pair of side gears and another of said pair of planet pinions of the first planet gear being engaged with one of said pair of gears of the center gear;

one of said pair of planet pinions of the second planet gear being engaged with another of said pair of side gears and another of said pair of planet pinions of the second planet gear being engaged with another of said pair of gears of the center gear; and

said pair of planet pinions of each planet gear define pitch circles which are slightly different.

2. The first differential according to claim 1, wherein

(S1.P'"'"'1/C1.P1)+(S2.P'"'"'2/C2.P2) is substantially equal to 2, wherein numbers of teeth of the side gears are S1 and S2, numbers of teeth of the gears of the center gear are C1 and C2, numbers of teeth of the planet pinions of the second planet gear are P1 and P'"'"'1, and numbers of teeth of the planet pinions of the first planet gear are P2 and P'"'"'2.

3. The first differential according to claim 1, wherein

said differential case and said first carrier are mounted rotatably on said one of said pair of axles.

4. A central differential for a four-wheel drive motor vehicle having a transmission, comprising:

a pair of axles;

a differential case rotatably supported on the axles;

a tubular body rotatably supported around one of the axles and operatively connected to an output of the transmission so as to be rotated;

first and second carriers, the first carrier being secured to the differential case, and the second carrier being rotatably supported on the tubular body;

motor vehicle having a differential disposed in the differential case between the axles so as to perform a differentiating operation for right and left wheels of a set of drive wheels of the motor vehicle;

the central differential further comprising

a pair of side gears formed on the tubular body;

a center gear having a pair of gears and rotatably mounted on the tubular body;

a pair of planet gears,

each of said pair of planet gears comprising a pair of planet pinions and each of said pair of planet gears being rotatably supported in a corresponding one of said first and second carriers, respectively;

one of said pair of planet pinions of each planet gear being engaged with a corresponding one of said pair of side gears, respectively, and another of said pair of planet pinions of each planet gear being engaged with a corresponding one of said pair of gears of the center gear, respectively;

the second carrier being operatively connected to another set of drive wheels of the motor vehicle so as to transmit output of the second carrier to said another set of drive wheels; and

numbers of teeth of both side gears, numbers of teeth of the gears of the center gear, and numbers of teeth of the planet pinions being such that speeds of the gears of the center gear are equal to each other.

5. The central differential according to claim 4, further comprising

a final gear of the transmission is splined to the tubular body.