Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Patent
1997-12-17
1999-09-07
Marmor, Charles A
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
477 48, B60K 4114
Patent
active
059478624
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for controlling the gear ratio of a continuously variable transmission in a vehicle having a prime mover and an output governor device. To them are specified, via an accelerator pedal, theoretical rotational speed values of the prime mover. The theoretical rotational speed values are compared with measured actual rotational speed values. The device also has a setting device for changing the gear ratio of the continuously variable transmission. Control signals of a rotational speed governor are fed to it which result from the differences between theoretical and actual rotational speed values of the prime mover.
As a rule, the above mentioned continuously variable transmissions have bevel discs which, between them, enclose a rotary traction means. Axial contact pressures are exerted upon the bevel discs via a hydraulically working setting device.
The position of the throttle valve, or the like, serves as an input parameter for control of a continuously variable transmission via a control part (gas or accelerator pedal). For said input parameter, a theoretical rotational speed value, which is compared with the actual rotational speed value, is preset for the prime mover. Control divergences release the adjustment of the transmission, for example, by a solenoid valve. When the rotational speed is too low, the transmission ratio becomes smaller, when the rotational speed is high, it is adjusted larger. The control loop is closed by a repeated comparison with the actual rotational speed value.
In the operational strategies known already, the point of departure is that by the position of the control part the driver presets a desired performance from which results a desired engine rotational speed nM-theor, optionally under the influence of optimization criteria (mode of driving, driving environment). An optimization criterion can be, for example, the intersection point of a line of minimal fuel consumption with the actual line of the throttle valve position in the engine performance graph. The appertaining transmission ratio of the continuously variable transmission iV-theor. then results as a sequential parameter from the desired engine rotational speed nM-theor. and the actual vehicle speed vF. By using an electronic transmission control, it is possible to select different driving programs (as a rule economical or performance oriented) by a switch which can be situated, for example, on the selector lever.
Depending on which driving program is active, different reaction speeds, according to the parameter of the change in position of the throttle valve or the adjusted speed, are to be expected or taken into consideration.
The inertia moments of the transmission and the engine are essential for the demands on the hydraulic system, kinematics and the time characteristic of the system. This means, among other things, that too quick a shift during a down change leads to braking of the vehicle, since all of the rotating masses of the vehicle inertia must be accelerated and that no increase in speed is to be registered during the shift, since the engine torque is fully used for acceleration of the rotating masses of the transmission of the engine. This fact makes itself disadvantageously noticeable in certain driving conditions. Thus, for example, when the driver expects an instantaneous acceleration during a down change. In order to ensure a continuous speed increase, the adjusting speed, that is, the change of transmission ratio of the continuously variable transmission, must be variable over the time. The timed change of the adjustment is here of basic significance for the quality of the control and thus finally also for the driving comfort obtainable.
DE-A 36 36 463 proposes a method for limiting the variation speed. Such limitation results essentially for reasons of comfort, since torque jumps and undesired vehicle accelerations or decelerations must be avoided. There must also be brought about, as direct as possible, a relation between the position of
REFERENCES:
patent: 4509125 (1985-04-01), Fattic et al.
patent: 4683779 (1987-08-01), Osanai et al.
patent: 4811225 (1989-03-01), Petzold et al.
patent: 4852429 (1989-08-01), Kunzer et al.
patent: 5009129 (1991-04-01), Morimoto et al.
patent: 5782719 (1998-07-01), Adachi
patent: 5820514 (1998-10-01), Adachi
patent: 5860891 (1999-01-01), Bauerle
Eschrich Gerhard
Knapp Thomas
Runge Wolfgang
Lund Scott
Marmor Charles A
ZF Friedrichshafen AG
LandOfFree
Device for controlling the gear ratio of a continuously variable does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for controlling the gear ratio of a continuously variable, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for controlling the gear ratio of a continuously variable will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1798186