Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1998-06-23
2001-03-20
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S061000, C701S065000
Reexamination Certificate
active
06205386
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and an arrangement for automatically determining a quantity for a motor vehicle which represents the rpm ratio between the transmission and the wheels.
BACKGROUND OF THE INVENTION
From the state of the art, it is known to control (open loop and/or closed loop) the transmission functions via an electronic control apparatus. In this connection, reference can be made, for example, to the publication “Bosch Automotive Handbook”, 3rd edition, pages 548 to 551. A differential transmission (axle differential) is arranged between the transmission and the driven wheels and has a specific rpm ratio. The transmission ratio of the axle differential transmission is a quantity which is used in an electronic transmission control in order, for example, to determine the transmission output rpm from the wheel rpms when a transmission output rpm sensor is defective.
It is conventional to build in differential transmissions having different differential transmission ratios into different vehicle models of a series of vehicles. If one would have to provide these different differential transmission ratios in the software of the transmission control apparatus, then this would cause increased complexity because of the different software for the individual vehicle models. In order not to have to provide the differential transmission ratio in the software, a function is integrated into the transmission control apparatus via which the built-in differential transmission ratio can be learned.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a reliable and simple automatic determination of the differential transmission ratio.
In a motor vehicle having a transmission and wheels operatively connected to the transmission, the method of the invention is for automatically determining the rpm ratio (i
Diff
) between the transmission and the wheels. The method includes the steps of: detecting a first rpm value (Nij) representing the rpm of at least one of the wheels; detecting a second rpm value (Nab) representing the rpm of a component of the transmission; forming a driving state quantity (FZ) representing a driving state of the motor vehicle; determining a pregivable operating state when the driving state quantity (FZ) represents a driving state which is essentially a steady state driving state; and, determining the rpm ratio (i
Diff
) in dependence upon the detected rpm values when the pregivable operating state is determined.
The invention proceeds from a motor vehicle having a transmission and wheels wherein a specific rpm ratio is present between the transmission and the wheels. The invention relates to the automatic determination of a quantity which represents the rpm transmission ratio between the transmission and the wheels. For this purpose, first and second rpm values are detected which represent the rpm of at least one wheel and the rpm of a component of the transmission. Furthermore, a driving state quantity is formed which represents the instantaneous driving state of the motor vehicle. The essence of the invention is that a pregiven operating state is then determined when the formed driving state quantity indicates a driving state which is essentially steady state. This means that the pregiven operating state is then determined when the driving state (and therewith especially the formed driving state quantity) remains essentially unchanged as a function of time. The determination of the sought rpm ratio takes place in dependence upon the detected rpm values when the pregiven operating state is detected.
With the procedure of the invention, it is ensured that the automatic determination of the differential transmission ratio is not made incorrect by dynamic driving states. If one would omit consideration of the determination of the pregiven driving state as provided by the invention, then the automatic determination of the differential transmission ratio could lead to a defective detection of the built-in differential transmission ratio because the computation could take place in a dynamic driving state. The risk of a defective detection of the differential transmission ratio can be minimized by limiting the determination of the differential transmission ratio to a driving state having only slight driving dynamics (steady state or quasi steady state driving state).
With the invention, the driving dynamics of the vehicle when automatically determining the differential transmission ratio is considered. In addition to this consideration, a further embodiment of the invention provides for a stepped method which ensures, for example, a rapid determination of the differential transmission ratio after the transmission control apparatus is newly built in. For this purpose, and according to the invention, a preliminary value for the differential transmission ratio is determined in dependence upon the detected rpm values when at least one of the detected rpm values exceeds a pregiven threshold value. The condition for the determination of the preliminary value is therefore only coupled to the condition that the vehicle, in general, has a certain minimum speed. For the determination of the preliminary value, it is at first not considered whether the vehicle is or is not in a driving state which changes greatly as a function of time. In addition, and as described above, a driving state quantity is formed which represents the driving state of the motor vehicle. The pregiven driving state is then likewise determined as described above when the formed driving state quantity indicates a driving state which is essentially steady state. This means that the pregiven driving state is then determined when the driving state and therefore especially the formed driving state quantity remains essentially unchanged as a function of time. Only when this pregiven driving state (steady state or quasi steady state operating state) is present, is a more precise value for the differential transmission ratio determined in dependence upon the detected rpm values.
After a transmission control apparatus is newly built in, under some circumstances, no steady state or quasi steady state driving condition possibly occurs for a relatively long time. For this reason, the second variation of the application leads to the condition that a preliminary value is learned for the differential transmission ratio directly after the transmission control apparatus is built in. This preliminary value is then replaced by a value having a higher reliability when a steady state or quasi steady state driving state is detected. The second variation of the invention thus shows a way to obtain as fast as possible at least an imprecise value for the differential transmission ratio, but also offers the possibility to correct the same.
In an advantageous configuration of the invention, it is provided that the determination of the driving state quantity takes place in dependence upon the detected first and/or the detected second rpm value. That is, the driving state is, for example, determined via the transmission output rpm or via the rpm of the wheel. The pregiven operating state can then be determined when the time-dependent change of the formed driving state quantity lies below a threshold value. It is especially provided that at least the transmission output rpm is applied for determining the driving state quantity.
Furthermore, it can be provided that the driving state quantity is determined in dependence upon: the detected position of the accelerator pedal actuated by the driver; the position of the brake pedal actuated by the driver; and/or, in dependence upon a motor value which represents an operating parameter of the motor of the vehicle.
In a further advantageous embodiment, the differential transmission ratio is only determined when at least one of the detected rpm values exceeds a pregiven threshold value.
The differential transmission ratio, which is determined in accordance with the invention, and/or the specific preliminary value, which is determined according to the in
Hofmann Holger
Stroh Walter
Cuchlinski Jr. William A.
Marc-Coleman Marthe
Ottesen Walter
Robert & Bosch GmbH
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