Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2000-06-15
2001-11-13
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
C074S335000
Reexamination Certificate
active
06315692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus for an automatic transmission of a vehicle such as a motor vehicle in which the transmission has a plurality of hydraulic engaging elements for speed changing.
2. Description of Related Art
As this kind of control apparatus, there has conventionally been known a control apparatus which comprises a plurality of speed-change control valves corresponding to a plurality of hydraulic engaging elements and a plurality of speed-change solenoid valves corresponding to these speed-change control valves. The hydraulic oil pressure in each of the plurality of hydraulic engaging elements is adjusted depending on a signal pressure from a corresponding speed-change solenoid valve with a line pressure from a hydraulic oil pressure source serving as a base pressure. In this apparatus, the hydraulic oil pressure in each of the hydraulic engaging elements can be directly controlled by a controller which is made up of a vehicle-mounted computer through each of the speed-change solenoid valves. Therefore, the apparatus is advantageous in reducing the speed change shocks.
Further, there is also known an apparatus which is provided with a pressure regulating means for varying the line pressure, wherein the line pressure is decreased at the time of cruising of the vehicle so that the driving load of the hydraulic oil pressure source can be reduced, thereby improving the specific fuel consumption.
In the above-described apparatus in which the hydraulic oil pressures in the hydraulic engaging elements are controlled depending on the signal pressures from the speed-change solenoid valves, the deterioration in the controllability of the speed-change solenoid valves by the clogging or inclusion of foreign matter in the speed-change solenoid valves will be a big problem in commercializing the product.
Foreign matter which has clogged or has found its way into a speed-change solenoid valve can be removed by opening the solenoid valve. Thus, there is known an apparatus in which cleaning work is performed by intermittently opening the speed-change solenoid valve in a neutral range or in a parking range to thereby remove the foreign matter.
In the above-described conventional apparatuses, cleaning work is not performed while the vehicle is running in a running range. Therefore, there is a problem in improving the toughness against (or the ability to successfully cope with) the clogging or inclusion of foreign matter in the speed-change solenoid valve.
In view of the above-described points, the present invention has an object of providing a control apparatus for an automatic transmission of a vehicle in which the cleaning work to remove foreign matter can be performed during running of the vehicle without affecting the hydraulic oil pressure in the hydraulic engaging elements, whereby the toughness against the inclusion of foreign matter is improved.
SUMMARY OF THE INVENTION
In order to attain the above and other objects, the present invention is a control apparatus for an automatic transmission of a vehicle, the transmission having a plurality of hydraulic engaging elements for speed changing, the apparatus comprising: a plurality of speed-change control valves corresponding to the hydraulic engaging elements; a plurality of speed-change solenoid valves corresponding to the speed-change control valves, wherein a hydraulic oil pressure in each of the hydraulic engaging elements is regulated depending on a signal pressure from a corresponding speed-change solenoid valve with a line pressure from a hydraulic oil pressure source serving as a base pressure; and control means for varying, at a time of non-speed-changing, an opening degree of a speed-change solenoid valve corresponding to a predetermined speed-change control valve which corresponds to a hydraulic engaging element of a then-established speed transmission train, the opening degree being varied within a range in which there is outputted a signal pressure higher than a minimum signal pressure required to fully open the predetermined speed-change control valve.
By varying the opening degree of the speed-change solenoid valve within the above-described range, the foreign matter inside the speed-change solenoid valve can be removed without affecting the hydraulic oil pressure in the hydraulic engaging element. In addition, since the cleaning work can be performed during running of the vehicle by varying the opening degree of the speed-change solenoid valve, the cleaning work can be made at a higher frequency, with the result that the toughness against the clogging of foreign matter can be improved.
Preferably, the apparatus further comprises pressure regulating means for varying the line pressure depending on an operating condition of the vehicle. If the line pressure is thus decreased by the pressure regulating means below a maximum set pressure, the signal pressure required to make the hydraulic oil pressure in the hydraulic engaging element equal to the line pressure by fully opening the speed-change regulating valve is lowered, and the above-described range becomes wider. As a result, the amount of change in the opening degree of the speed change solenoid valve can be secured large, and the cleaning effect is improved. Therefore, in case the pressure regulating means to vary the line pressure depending on the running condition of the vehicle is provided, it is preferable to perform the varying of opening degree of the speed-change solenoid valve by the above-described control means at the time of non-speed-changing and at a time of line pressure control mode in which the line pressure is decreased by the pressure regulating means below a maximum set pressure.
REFERENCES:
patent: 5127287 (1992-07-01), Taniguchi et al.
patent: 5971889 (1999-10-01), Ohashi et al.
Suzuki Tadahiro
Takahashi Tooru
Yamada Kimiaki
Armstrong Westerman Hattori McLeland & Naughton LLP
Honda Giken Kogyo Kabushiki Kaisha
Wright Dirk
LandOfFree
Control apparatus for automatic transmission of vehicle 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 apparatus for automatic transmission of vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control apparatus for automatic transmission of vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2617151