Epicycloidal gear type speed change gear system

Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Speed responsive clutch or brake

Patent

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Details

475123, 475159, 475900, B60K 4126, B60K 1708, F16H 5710

Patent

active

054782929

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a speed change gear system for changing between forward and rearward movement and for changing a speed of a vehicle by selectively fixing sun gears, carriers and ring gears of a plurality of epicycloidal gear devices with respective clutches, and, more particularly, to an epicycloidal type speed change gear system with an output shaft coupled to a brake to absorb a rotational energy which is generated in changing between forward and rearward movement of a vehicle.


DESCRIPTION OF RELATED ART

A prior art system, as represented by the schematic diagram of a epicycloidal gear type speed change gear system 51 in FIG. 4, provides a driving source 52 such as an engine or a torque converter, an input shaft 53 which is driven by the drive source 52, and an R sun gear 54 and an F sun gear 55 which are coupled to the input shaft 53. In addition, the epicycloidal gear type speed change gear system has an R planetary gear 57 which is carried by the R carrier 56 and is engaged with the R sun gear 54, an R clutch 58 for fixing the R carrier 56 to a case 59 or releasing the R carrier 56 from the case 59, an R ring gear 60 which engages with the R planetary gear 57, and a carrier 61 coupled to the ring rear 60. Furthermore, the epicycloidal gear type speed change gear system has an F planetary gear 62 which is carried by the carrier 61 and engaged with the F sun gear 55, an F ring gear 63 which is engaged with the F planetary gear 62, and an F clutch 64 for fixing the F ring gear 63 to the case 59 or releasing the F ring gear 63 from the case 59.
The above speed change gear system is provided with a third planetary gear 67 which is carried by the carrier 61 and is engaged with a third sun gear 65 and a third ring gear 66, a third clutch 68 which fixes or releases the third ring gear 66 to or from the case 59, and an output shaft 71 which connects the third sun gear 65, the second sun gear 69 and the first sun gear 70. In addition, a second planetary gear 73 which is carried by the carrier 61 and is engaged with the second sun gear 69 and the second ring gear 72, a second clutch 74 which fixes or releases the second ring gear 72 to or from the case 59, and a carrier 75 which is coupled with the second ring gear 72 are provided. Furthermore, a first planetary gear 77 is carried by the carrier 75 and is engaged with the first sun gear 70 and the first ring gear 76, and a first clutch 78 fixes or releases the first ring gear 76 to or from the case 59. The numeral 79 denotes an inertial member of a vehicle.
In case of changing over movement of a vehicle from the second forward gear operation to the second rearward gear operation in the above described arrangement of the system, the F clutch 64 and the second clutch 74 are released immediately upon the start of a speed changing operation. The second clutch 74 is then reengaged in advance of the engagement of the R clutch 58. Under this condition, the output shaft 71 is rotating due to inertial member 79 of the vehicle, and therefore the R carrier 56 is also rotating. As the hydraulic pressure of the R clutch 58 is gradually increased, the rotation of the R carrier 56 is gradually slowed down and finally stopped, and the input shaft rotation and the output shaft rotation coincide with the speed changing ratio for the second gear. At this time, the R clutch 58 absorbs a large energy in order to reversely rotate the inertial member 79 of the vehicle.
The following describes the changeover of rearward to forward movement, for example, from the first rearward gear operation to the second forward gear operation.
For the first rearward gear operation, the R clutch 58 is engaged; the first clutch 78 is engaged; the R carrier gear 56 and the first ring gear 76 are fixed to the case 59; and other clutches are kept released. To make the change, the R clutch 58 and the first clutch 78 are released, and then the second clutch 74 is engaged. In this case, the energy to be absorbed by the second clutch 74 approximates the inertia, whi

REFERENCES:
patent: 3815445 (1974-06-01), Gorrell et al.
patent: 4020932 (1977-05-01), Windish
patent: 4192409 (1980-03-01), Ueda

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