Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1992-10-30
1994-07-19
Bonck, Rodney H.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
475120, 477 34, 477138, F16H 6108
Patent
active
053298306
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a shift control apparatus for an automatic transmission for a vehicle, in which hydraulic pressures supplied to a plurality of frictional engaging elements are individually controlled to achieve a plurality of speed ratios, especially, allowing the driver to achieve positive starting of the vehicle even when the shift lever is slowly operated from the N position to the D position.
BACKGROUND OF THE INVENTION
An automatic transmission for a vehicle selectively supplies hydraulic fluid to frictional engaging elements such as clutches and brakes to connect a desired rotary element in its gear system to an input shaft of the transmission or fix the element to the transmission casing, thereby automatically changing the speed ratio according to operation conditions of the vehicle.
Such an automatic transmission for a vehicle is required to be small in speed-shift shocks to protect various parts and components and maintain comfortable drive feeling. For this purpose, an automatic transmission for a vehicle has been proposed which uses a proper electronic control over the hydraulic pressure and its supply timing to frictional engaging elements, aiming to achieve reduced speed-shift shocks.
As shown in FIG. 5 which shows an example of the structure of such an automatic transmission for a vehicle, a crank shaft 12 of an engine 11 is integrally connected with an impeller 14 of a torque converter 13. The torque converter 13 has the impeller 14, a turbine 15, a stator 16, and a one-way clutch 17. The stator 16 is connected to a transmission casing 18 through the one-way clutch 17. By the function of the one-way clutch, the stator 16 is allowed to rotate in the same direction as the crank shaft 12 but is not allowed to rotate in the reverse direction. The torque transmitted to the turbine 15 is transmitted to the input shaft 19 (hereinafter referred to as the "transmission input shaft") of a gear transmission apparatus to achieve four forward speeds and a single reverse speed disposed at the rear of the torque converter 13.
The gear transmission apparatus comprises three clutches 20, 21, and 22, two brakes 23 and 24, one one-way clutch 25, and one ravigneaux type planetary gear mechanism 26. The ravigneaux type planetary gear mechanism 26 comprises a ring gear 27, a long pinion gear 28, a short pinion gear 29, a front sun gear 30, a rear sun gear 31, and a carrier 32 which rotatably supports the pinion gears 28 and 29 and is rotatably engaged with the transmission input shaft 19.
The ring gear 27 is connected to a transmission output shaft 33. The front sun gear 30 is connected to the transmission input shaft 19 through a kickdown drum 34 and a front clutch 20. Furthermore, the rear sun gear 31 is connected to the transmission input shaft 19 through a rear clutch 21. The carrier 32 is connected to the transmission casing 18 through a low reverse brake 24 and the one-way clutch 25 and to the transmission input shaft 19 through a 4th-speed clutch 22 disposed at the rear end of the gear transmission apparatus. The kickdown drum 34 is integrally connectable to the transmission casing 18 by a kickdown brake 23. Torque passed through the ravigneaux type planetary gear mechanism 26 is transmitted from a drive gear 35 mounted to the transmission output shaft 33 to the drive shaft side of driving wheels (not shown).
The clutches 20 to 22 and the brakes 23 and 24 as frictional engaging elements individually comprise hydraulic mechanisms provided with engaging piston devices or servo mechanisms. These hydraulic mechanisms are operated through a hydraulic control unit (not shown) by hydraulic fluid generated by an oil pump 36 connected to the impeller 14 of the torque converter 13.
Detailed structure and functions of the mechanisms are already known, for example, in Japanese Patent Publication Laid-open 58-54270/1983, 58-46248/1983, or 61-31749/1986. Thus, selective engagement of various frictional engaging elements is achieved according to the position of a shift lever provided
REFERENCES:
patent: 3800629 (1974-04-01), Lentz
patent: 3881372 (1975-05-01), Miyauchi et al.
patent: 5010786 (1991-04-01), Hiramatsu et al.
patent: 5042328 (1991-08-01), Morishigo et al.
Furuichi Yoichi
Kan Shoji
Kitagawa Takeshi
Taki Takahiro
Takuma Hiroshi
Bonck Rodney H.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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