Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1998-05-05
2001-04-10
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S051000, C477S050000
Reexamination Certificate
active
06216076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to control systems of an automotive automatic transmission, and more particularly to the control systems of a select-shock suppression type which suppresses or at least minimizes uncomfortable select-shock which would occur when a shift lever of the transmission is shifted from a neutral (N) position to a driving (D) position. More specifically, the present invention is concerned with the select-shock control systems of a type which, for reducing the select-shock, controls a hydraulic pressure applied to a corresponding engaging element of the transmission upon such N→D shifting.
2. Description of the Prior Art
When, under idling of an engine, an accelerator pedal is depressed just after movement of a shift lever from a neutral (N) position to a drive (D) position, racing of the engine tends to occur because of delayed rising of hydraulic pressure as compared with rising of torque and rotation speed of the engine. That is, in such case, engagement of a corresponding clutch can not keep up with the rising of the engine speed, which tends to induce an uncomfortable select-shock.
The above-mentioned undesired phenomenon will be briefly described with reference to the time charts of
FIGS. 15A
to
15
H of the accompanying drawings. As is understood from the points “P1” of the time charts of
FIGS. 15A and 15C
(viz., “TH” and “PLDuty”), in the control system of the automatic transmission, a throttle opening degree (viz., depression degree of the accelerator pedal) is monitored, and a line pressure control is so made that the line pressure duty command signal “PLDuty” is instantly shifted to a higher level upon sensing a certain open degree of the throttle valve.
Thus, in the above-mentioned control system, as is understood from the points “P2” of the time chart of
FIG. 15E
(viz., “PL/C”), after the engine is about to race due to depression of the accelerator pedal, the hydraulic pressure for the low clutch starts to rise and instantly the clutch engaging pressure is raised by “&Dgr;P”. This instant rising of the low clutch engaging hydraulic pressure however interrupts the increasing torque and increasing rotation of the engine, which causes a sudden drop of the engine torque and engine speed as is understood from the points “P3” of the time charts of
FIGS. 15F and 15G
(viz., “TQ” and “Ne”). As is known, such sudden drop causes the uncomfortable select-shock.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a select-shock control system of an automotive automatic transmission, which is free of the above-mentioned drawback.
According to the present invention, there is provided a select-shock control system of an automatic transmission, which can suppress or at least minimize undesired select-shock which would occur when, under idling of an engine, an acceleration pedal is depressed just after movement of a shift lever from a neutral (N) position to a drive (D) position.
According to the present invention, there is provided a select-shock control system of an automotive automatic transmission in which an engaging element becomes engaged due to application of hydraulic pressure thereto when it is needed to shift the transmission from a neutral condition to a drive condition. The control system comprises a select determination section which determines whether or not the transmission has just been shifted from the neutral condition to the drive condition; an accelerator pedal depression sensing section which senses depression of an accelerator pedal; and a control section which, when the accelerator pedal depression sensing section senses the depression of the accelerator pedal just after determination of the drive condition from the neutral condition by the select determination section, positively induces an oblique rise of the hydraulic pressure from a first lower level which has been kept before depression of the accelerator pedal to a second higher level corresponding to the degree by which the accelerator pedal is depressed.
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patent: 4987982 (1991-01-01), Yamaguchi
patent: 5249483 (1993-10-01), Iizuka
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patent: 5323668 (1994-06-01), Nakagawa et al.
patent: 5733220 (1998-03-01), Iizuka
patent: 3-28571 (1991-02-01), None
patent: 9-68266 (1997-03-01), None
Fujita Yoshifumi
Takiguchi Masahiro
Foley & Lardner
Gibson Eric M
Jatco Corporation
Zanelli Michael J.
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