US 8,831,804 B2Granted

Method for controlling an automatic geared transmission

AssigneeZF Friedrichshafen AG

InventorRainer Petzold

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Abstract

A method of controlling an automatic geared transmission of a vehicle drive train. The transmission is linked, on the input side, to a hybrid drive which comprising an engine and an electric motor and, on the output side, to an axle drive and wheels. During vehicle stand still with the engine and/or electric motor operating and a disengaged drive train, rolling of the motor vehicle is prevented, or at least limited, by shifting the transmission. When the automatic geared transmission is in the neutral position (Gl=N), a safety function is activated to avoid uncontrolled rolling of the vehicle in which actuation of shift operating elements, the throttle and the brake pedal, as well as the rolling speed, are captured by sensors and in which, when the drive operating elements (shift operating element xSBE=0, throttle xFP=0, brake pedal xBP=0) are not activated, a starting gear is engaged once a predetermined limiting speed (vRoll>vGr) is exceeded.

Claims20

Dependent claims

A method of controlling an automatic geared transmission of a motor vehicle by a safety function wherein the vehicle includes, on an input side of the transmission, a hybrid drive comprising a combustion engine and an electric motor and at least a controllable friction clutch and, on the output side of the transmission, wheels which are driven via an axle drive, the method of the safety function comprising the steps of:

activating a safety function only after determining that:
a vehicle rolling speed (vRoll) is less than a predetermined minimum vehicle rolling speed (vmin), and
a rotational speed (nM) of at least one of the combustion engine and the electric motor is greater than a determined minimum rotation speed (nmin), and
the transmission is in a neutral gear, and
a brake is disengaged;
and
exiting the safety function when at least one of:
a shift actuation element is actuated (xSBE≠0);
a throttle is actuated (xFP≠0);
and
a brake pedal is actuated (xBP≠0);
while the safety function is activated, if the vehicle rolling speed (vRoll) exceeds a predetermined speed limit (vGr), then engaging a starting gear by a sequence of steps selected from the group of sequences of steps consisting of:
(A) engaging (Gl=GAnf) the starting gear, and
(B) disengaging (xK=0) the friction clutch, engaging (Gl=Ganf) the starting gear, and reengaging (xK=1) the friction clutch,
thereby providing drag torque braking of the vehicle by the at least one of the combustion engine and the electric motor;
wherein the safety function only provides for activation when the motor vehicle is unattended in one way or another and when the motor vehicle is not traveling in any direction.

13 more elements

A method of controlling an automatic geared transmission of a motor vehicle by a safety function wherein the vehicle includes, on an input side of the transmission, a hybrid drive comprising a combustion engine and an electric motor and, on the output side of the transmission, wheels which are driven via an axle drive, the method of the safety function comprising the steps of:

activating a safety function only after determining that:
a vehicle rolling speed (vRoll) is less than a predetermined minimum vehicle rolling speed (vmin), and
a rotational speed (nM) of at least one of the combustion engine and the electric motor is greater than a determined minimum rotation speed (nmin), and
the transmission is in a neutral gear, and
a brake is disengaged;
exiting the safety function when at least one of:
a shift actuation element is actuated (xSBE≠0) so as to shift the transmission out of the neutral gear;
a throttle is actuated (xFP≠0);
and
a brake pedal is actuated (xBP≠0);
while the safety function is activated, if the vehicle rolling speed (vRoll) exceeds a predetermined speed limit (vGr), then engaging a starting gear (xK=0);
thereby providing drag torque braking of the vehicle by the at least one of the combustion engine and the electric motor;
wherein the safety function only provides for activation when the motor vehicle is unattended in one way or another and when the motor vehicle is not traveling in any direction.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/128,056Filed 5 Nov 2009
Priority: DE 10 2008 043 5607 Nov 2008
Published: US 2011/0218699 A18 Sep 2011
Granted: 9 Sep 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification31 codes

B60W 30/18054
Related to particular drive situations: at stand still, e.g. engine in idling state
B60L 50/16
Using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines: with provision for separate direct…
B60W 10/02
Conjoint control of vehicle sub-units of different type or different function: including control of driveline clutches
B60W 10/11
Including control of change-speed gearings: stepped gearings