Automatic transmission controller

Details Automatic transmission controller Automatic transmission controller

1999-09-03

2001-02-13

Estremsky, Sherry (Department: 3681)

Interrelated power delivery controls, including engine control

Transmission control

Transmission controlled by engine

C701S066000

Reexamination Certificate

active

06186924

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic transmission controller and more particularly to the control of a solenoid valve that is used for changing gear ratios of an automatic transmission.
2. Description of the Prior Art
So far, a control method of a solenoid valve that is used for control of an automatic transmission is disclosed in the Japanese Patent Publication No. Hei 05-035293. In this solenoid valve control method, to make the program structure simple, control cycles in the steady state and the speed changing state were set at fixed times.
FIG. 5
(
a
), (
b
) and (
c
) are time charts showing the operations of the above-mentioned conventional transmission controller. The solenoid valve control cycle cannot be made shorter than a certain time from the viewpoint of hydraulic pressure response and to avoid a natural frequency of a vehicle body. So, the control cycle is set at 28.57 ms as illustrated. In contrast to this, in the main routine which computes controlled variables, the solenoid valve is controlled as fast as possible, for instance, at a control cycle of 5 ms as shown in the example in
FIG. 5
to improve manpower taking accuracy and control accuracy of a throttle opening sensor, etc., that is, to get new information precisely.
In the above-mentioned automatic transmission control method, the solenoid valve is controlled at an interval of fixed cycle time in the steady state as well as the speed change state and therefore, there was such a problem that the speed change control was delayed to start by maximum one control cycle when changing the steady state to the speed change state. In other words, even when the speed change is judged as required in the program main process, the duty solenoid control started at a time t
2
as the next duty solenoid control process is set at the time t
2
. Therefore, the control is delayed by maximum one cycle.
SUMMARY OF THE INVENTION
The present invention is made to solve the above-mentioned problems and make the control delay short when changing the transmission from the steady state to the speed changing state and improve accuracy of the oil pressure control during the speed change while suppressing fluctuation of the delaying time.
In order to achieve the above object, in a first invention, the above-mentioned solenoid valve control cycle is set at a longer time than that in the steady state by a switching means when a judging means judged that the speed change is required.
Further, in a second invention it is judged that the speed change is not required when the solenoid valve control duty is 0% and the speed change is required when the control duty is other than 0%.
The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 4518068 (1985-05-01), Oguma et al.
patent: 5042328 (1991-08-01), Morishige et al.
patent: 5133231 (1992-07-01), Goto et al.
patent: 5-35293 (1993-05-01), None

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