Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2000-07-28
2001-08-07
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
Reexamination Certificate
active
06270439
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic transmission for an automobile and more particularly to a hydraulic control apparatus of an automatic transmission.
2. Prior Arts
Generally, in automatic transmissions for automobiles, gear ratios are automatically selected according to vehicle operating conditions such as engine load, vehicle speeds and the like and those gear ratios are obtained by selectively engaging friction elements such as clutches and brakes in automatic transmissions. In case of the automatic transmission employing a planetary gear for the transmission gear, the frictional engaging elements are composed of hydraulically controlled multiple disc clutches and hydraulic brakes.
The control of these friction elements is a key technology of the automatic transmission and many techniques have been proposed. Among them, Japanese Patent Application Lid-open (Unexamined Publication) No. Toku-Kai Hei. 7-269685, which has been proposed from the inventor of the present invention, discloses a so-called direct shift control method using pressure control valves provided in respective friction elements.
In the prior art, an electromagnetic type pressure control valve operated on forward running is provided on the friction elements, respectively and each of these pressure control valves performs a shift control based on an independent transient hydraulic characteristic so as to alleviate a shift shock and at the same time to shorten a shift time.
Further, Japanese Patent Application Laid-open No. Toku-Kai-Hei 7-269685 proposes a hydraulic control apparatus having two fail-safe valves for automatically avoiding such a hazardous condition as both low and reverse brake and overdrive clutch are simultaneously engaged when the gear is engaged in a first gear at “D” range.
However, the electromagnetic type pressure control valve is complicated in construction and therefore high in manufacturing cost. Furthermore, since one electromagnetic type pressure control valve must be provided for each of the frictional engaging elements, not only the total cost becomes high, but also the size of the apparatus increases.
Further, thefail-safevalvesproposedin Toku-Kai-Hei 7-269685 makes the hydraulic control system more complicated and increases the size and cost of the apparatus.
SUMMARY OF THE INVENTION
In view of the aforementioned problems, it is an object of the present invention to provide a low cost hydraulic control apparatus having a simple construction and small size of an automatic transmission.
The hydraulic apparatus comprises a first friction element engaged when a shift lever is positioned at “1” (first gear hold) range, a second friction element engaged when gearing of gear sets of a transmission is at a second gear position, a third friction element engaged when gearing of the gear sets is at a third gear position, a fourth friction element engaged when gearing of the gear sets is at least at a first gear position, a first pressure control valve for regulating a hydraulic pressure to be supplied to the first and third friction elements, respectively, a second pressure control valve for regulating a hydraulic pressure to be supplied to the second friction element, a reverse friction element engaged only when the select lever is positioned at “R” (reverse) range and a first hydraulic passage changeover valve provided between the first pressure control valve and the first and third friction elements for changing over hydraulic passages between the first friction element and the second friction element.
REFERENCES:
patent: 4483215 (1984-11-01), Ishimaru et al.
patent: 4726261 (1988-02-01), Kato et al.
patent: 5184528 (1993-02-01), Mochizuki
patent: 5382201 (1995-01-01), Izuka
patent: 5383820 (1995-01-01), Mori
patent: 5411446 (1995-05-01), Hirose
patent: 5441459 (1995-08-01), Inukai et al.
patent: 5478288 (1995-12-01), Sakakibara et al.
patent: 5664020 (1997-09-01), Kamada et al.
patent: 5836845 (1998-11-01), Sakaguchi et al.
patent: 5857935 (1999-01-01), Takiguchi
patent: 5938563 (1999-08-01), Nishio et al.
patent: 6139459 (2000-10-01), Suzuki
patent: 0 537 818 (1993-04-01), None
patent: 0 725 235 (1996-08-01), None
patent: 7-269685 (1995-10-01), None
patent: WO 94/15809 (1994-07-01), None
Fuji Jukogyo Kabushiki Kaisha
Marmor Charles A
Parekh Ankur
Smith , Gambrell & Russell, LLP
LandOfFree
Hydraulic pressure control apparatus of automatic transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic pressure control apparatus of automatic transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic pressure control apparatus of automatic transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520015