Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2000-03-02
2001-10-09
Estremsky, Sherry (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
C475S120000, C475S127000, C477S906000
Reexamination Certificate
active
06299560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for a vehicle automatic transmission comprising two hydraulic coupling elements belonging to a first group and two or more hydraulic coupling elements belonging to a second group and adapted to selectively establish a plurality of shift ranges through a simultaneous engagement of the two hydraulic coupling elements of the first group and a simultaneous engagement of either one of the two hydraulic coupling elements of the first group and any one of the two or more hydraulic coupling elements of the second group.
2. Description of the Related Art
Conventionally, as a control device of this kind, a control device is known in which a shift control valve is provided for each of the hydraulic coupling elements of the first and second groups so that supplying and draining of oil to and from the respective hydraulic coupling elements are individually controlled by the respective shift control valves. In this control device, however, when the shift control valves malfunction, there may be caused a problem that oil happens to also be supplied to the other hydraulic coupling elements than the hydraulic coupling elements that are being intended to establish a desired shift range, resulting in a double meshing in which a plurality of shift ranges are established at the same time.
Here, in the vehicle automatic transmission in which a plurality of shift ranges are selectively established through a simultaneous engagement of two hydraulic coupling elements of the first group and a simultaneous engagement of either one of the hydraulic coupling elements of the first group and any one of the hydraulic coupling elements of the second group, however, as long as the shift control valves do not malfunction, there happens no case in which oil is supplied to three hydraulic coupling elements simultaneously. Japanese Patent Unexamined Publication No. Hei. 8-42681 discloses a conventional control device in which a fail-safe valve is interposed between shift control valves other than those corresponding to hydraulic coupling elements that are being intended to establish a predetermined single shift range and an oil supply passage communicating with a hydraulic pressure source, the fail-safe valve being constructed so as to freely be switched over between an open position where the oil supply passage is connected to the other shift control valves and a closed position where such a connection is disconnected. The fail-safe valve so structured is switched over to the closed position when hydraulic pressures of the respective hydraulic coupling elements of first and second groups are inputted into the fail-safe valve to be found that any three of those hydraulic pressures increase. According to this construction, oil is prevented from being supplied to the hydraulic coupling elements corresponding to the other shift control valves, a double meshing being thereby prevented.
In the conventional example, there is a need to form individual oil chambers into which hydraulic pressures of the respective hydraulic coupling elements of the first and second groups are inputted individually, and when the total number of hydraulic coupling elements is increased to meet an increase in the number of shift ranges, the number of oil chambers is also increased. As a result of this, the length of the fail-safe valve is increased, and there is increased the possibility that a valve stick is caused. Moreover, the diameter of the valve element of the fail-safe valve is made thicker, and the mass of the valve element is increased, this deteriorating the response of the fail-safe valve when switched over from the open position to the closed position.
SUMMARY OF THE INVENTION
The present invention was made to solve the above problem and an object thereof is to provide a control device for a vehicle automatic transmission which can improve the toughness against the valve stick and response in switching over of a fail-safe valve by making it smaller in size.
With a view to solving the aforesaid problem, according to the present invention, there is provided a control device for a vehicle automatic transmission comprising two hydraulic coupling elements belonging to a first group and two or more hydraulic coupling elements belonging to a second group and adapted to selectively establish a plurality of shift ranges through a simultaneous engagement of the two hydraulic coupling elements of the first group and a simultaneous engagement of either one of the two hydraulic coupling elements of the first group and any one of the two or more hydraulic coupling elements of the second group, wherein shift control valves are provided which individually control the supplying and draining of oil to and from the respective hydraulic coupling elements of the first and second groups, and wherein a fail-safe valve is interposed between the shift control valves other than the shift control valves corresponding to the hydraulic coupling elements that are being intended to establish a predetermined single shift range and an oil supply passage communicating with a hydraulic pressure source, the fail-safe valve being able to freely be switched over between an open position where the oil supply passage is connected to the other shift control valves and a closed position where the connection is disconnected, wherein a resultant signal valve is provided that is adapted to output a signal pressure when hydraulic pressures of the two hydraulic coupling elements of the first group are inputted into the resultant signal valve to be found that the hydraulic pressures of the two hydraulic coupling elements increase, and further wherein the fail-safe valve is constructed so as to be switched over to the closed position when hydraulic pressures of the respective hydraulic coupling elements of the second group and the signal pressure are inputted into the fail-safe valve to be found that any two or more of the hydraulic pressures and signal pressure increase at the same time.
According to the invention, when oil is supplied to any one of the hydraulic coupling elements of the second group in a state in which the two hydraulic coupling elements of the first group are in engagement, that is, in a state in which a signal pressure is outputted from the resultant signal valve, the fail-safe valve is switched over to the closed position for effecting a fail safe. In addition, even if only one of the two hydraulic coupling elements of the first group is in engagement or the two hydraulic coupling elements are released, that is, no signal pressure is outputted, when oil is supplied to two or more of the hydraulic coupling elements of the second group, the fail-safe valve is switched over to the closed position for effecting a fail safe.
Moreover, there may be provided a single oil chamber for input of a signal pressure in the fail-safe valve instead of the two oil chambers into which the hydraulic pressures of the two hydraulic coupling element of the first group are inputted. This serves to shorten the valve length of the fail-safe valve and to thin the diameter of the valve element of the fail-safe valve to reduce the weight thereof.
REFERENCES:
patent: 4903551 (1990-02-01), Hiramatsu et al.
patent: 5505868 (1996-04-01), Eaton
patent: 5888169 (1999-03-01), Jong
patent: 6102826 (2000-08-01), Takahashi et al.
patent: 0 294 033 (1988-12-01), None
patent: 0 694 713 (1996-01-01), None
patent: 0 837 268 (1998-04-01), None
patent: 8-42681 (1996-02-01), None
Patent Abstracts of Japan, vol. 016, No. 253 (M-1263), Jun. 9, 1992 & JP 04 060271, Feb. 26, 1992.
Fujioka Masato
Nakajima Kenji
Takahashi Tooru
Arent Fox Kintner & Plotkin & Kahn, PLLC
Estremsky Sherry
Honda Giken Kogyo Kabushiki Kaisha
LandOfFree
Control device for vehicle 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 Control device for vehicle automatic transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control device for vehicle automatic transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2585266