Interrelated power delivery controls – including engine control – Transmission control – With brake control
Patent
1994-12-14
1996-08-27
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
With brake control
477114, 477900, 477901, B60K 4120
Patent
active
055495257
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the control of an automatic transmission in accordance with the preamble of the first claim.
BACKGROUND OF THE INVENTION
In many cases, vehicles having automatic transmissions begin to creep upon engagement of a gear and idling speed of the engine, since the latter generates a torque upon the transmission even when no throttle is actuated.
DE 41 18 474 A1 has disclosed an anti-creep control for an automatic vehicle transmission. When the vehicle speed and opening angle of the engine throttle valve are zero or near zero and the brake is actuated, the transmission of the torque is interrupted or reduced. The anti-creep control remains activated as long as the engine runs at idle speed and the vehicle remains,braked even if the brake system is released.
The fact that when braking the vehicle on an incline, it can be protected against unintended backward rolling with only one brake has proved disadvantageous in the case of a complete interruption of the torque.
SUMMARY OF THE INVENTION
The invention is based on the problem of preventing the vehicle from rolling backward on an incline when the torque diminishes. The problem is solved according to the invention by the characteristic features of claim 1. It is advantageous here that the remaining drive torque overcompensates for the influences, produces a slight creep and thereby warns the driver that a gear is still engaged. The magnitude of the drive torque needed for this depends on the inclination of the vehicle and also on the vehicle load.
The inclination of the vehicle is detected by a gradient sensor which can be an accelerometer. A signal is evaluated only when the marginal conditions, the vehicle speed and opening of the throttle valve, are zero or near zero in order to ensure that the vehicle is not in an acceleration condition. A characteristic line, which results from coordinating the clutch pressure with the vehicle inclination and the vehicle load, is stored in an electronic unit.
In development of the invention it is proposed to take into account the load condition of the vehicle in the control. Compared to an unloaded vehicle, the load produces a change of the axle load. The distribution of the load is different for the front and rear axles. The inclination of the vehicle thereby changes and causes an adulteration of the signal of the gradient sensor. This misinformation produces a higher drive torque. The misinformation is corrected by a signal which is a function of the vehicle load. The signal of a light-range regulation of the vehicle headlights or the signal of a level adjustment of the vehicle can be used as a standard for the load condition of the vehicle. Likewise, sensors can be used which measure the distance of the vehicle from the road.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment is shown in the drawings.
In the drawing:
FIG. 1 shows block diagram of the construction of the control device; and
FIG. 2 shows a flow chart of the program for the vertical uncoupling.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows an automatic transmission 10 which is connected by an input shaft 11 with an engine 9. The transmission 10 has clutches, not shown, the torque transmission of which is determined by electrical hydraulic actuators, not shown. Said actuators are controlled by an electronic control unit 6 which has at its disposal a microprocessor 7 for signal processing together with a memory 8 in which instructions for coordinating the clutch pressure with the vehicle load and the vehicle inclination are stored. Input quantities for the electronic control unit 6 are: a signal from a speed-range selector 1, the signal v from a speed sensor 2 which stands for the vehicle velocity, the signal DKI from an engine throttle valve 3, the signal from a gradient sensor 4, and the signal of a vehicle light-range regulation or vehicle level regulation, or the signals from distance sensors 5.
FIG. 2 shows the flow chart of the vertical uncoupling program. The program is activated upon engagement of a
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Kwon Peter
Marmor Charles A.
ZF Friedrichshafen
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