Method for controlling an automatic gearbox of a motor vehicle in the vent that the gas/pedal is spontaneously released

• US 20040098181A1
• Filed: 04/22/2003
• Published: 05/20/2004
• Est. Priority Date: 11/11/2000
• Status: Active Grant

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Jauch, Friedemann, Kiefer, Michael, Schuler, Franz-Josef, Henneken, Markus, Mauz, Thomas
• Granted Patent: US 6,879,900 B2
• Time in Patent Office: Days
• US Class Current: 701/51
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: F16H 2059/142 of driving resistance calculated from weight, slope, or the like
• CPC Class Codes: F16H 2059/144 characterised by change between positive and negative drive line torque, e.g. torque changes when switching between coasting and acceleration
• CPC Class Codes: F16H 2059/183 Rate of change of accelerator position, i.e. pedal or throttle change gradient
• CPC Class Codes: F16H 2061/163 Holding the gear for delaying gear shifts under unfavorable conditions, e.g. during cornering
• CPC Class Codes: F16H 59/141 of rate of change of torque or torque demand
• CPC Class Codes: F16H 59/48 Inputs being a function of acceleration
• CPC Class Codes: F16H 61/16 Inhibiting or initiating shift during unfavourable conditions, e.g. preventing forward reverse shift at high vehicle speed, preventing engine over speed unintentional control input F16H61/18

Abstract

A method for controlling an automatic transmission of a motor vehicle in the event of a spontaneous gas/pedal release (FastOff). The automatic transmission is driven by an internal combustion engine which can be influenced by an accelerator pedal and a signal proportional to a pedal position is fed to an electronic transmission control in which shifting characteristic field is stored and the spontaneous gas/pedal release (FastOff) is detected and an upshift block (FFO=1) is activated when a pedal position gradient (PSTG) falls below a pedal gradient threshold (KF_PSTG). The mode of the upshift block (FFO=1) is removed when a traction operation is detected when an actual engine torque (MMM) exceeds a push-pull line (KL_ZS) stored as a function of a value equivalent to an engine rotational speed (NMO) in dependence on a vehicle acceleration/deceleration (AIST) dependent on an overall tractional resistance (GFW) and pedal gradient thresholds (KW_PSTGPOS, KW_PSTGNEG).

Claims

1. Method for control of an automatic transmission of a motor vehicle in the event of a spontaneous gas/pedal release (FastOff);

wherein the automatic transmission is driven by an internal combustion engine that can be influenced with an accelerator pedal and signal proportional to the pedal position is fed to an electronic transmission control where has been stored a shifting characteristic field; and

wherein the spontaneous gas/pedal release (FastOff) is detected and an upshift block (FFO=1) is activated when a pedal position gradient (PSTG) is smaller than a pedal gradient threshold (KF_PSTG), characterized in that the mode of the upshift block (FFO=1) is lifted upon detection of a traction operation when an actual engine torque (MMM) exceeds a push-pull characteristic line (KL_ZS) stored as function of a value equivalent to an engine rotational speed (NMO) depending on a vehicle acceleration/deceleration (AIST) dependent on the overall tractional resistance (GFW) and pedal gradient thresholds (KW_PSTGPOS, KW_PSTGNEG).

2. Method according to claim 1, characterized in that the mode of the upshift block (FFO=1) is left when traction operation is detected and the actual pedal position value (PST) is higher than the pedal position value (PST1) when detecting the spontaneous gas/pedal release (FastOff) plus an offset value (KW_PSTO1).

3. Method according to claim 1 or 2, characterized in that the mode of the upshift block (FFO=1) is left when a minimum vehicle velocity is underrun.

4. Method according to any one of claims 1 to 3, characterized in that the upshift block (FFO=1) is lifted when during detected traction operation the vehicle acceleration/deceleration (AIST) is higher than a threshold (KL_AFZG) stored in a characteristic line depending on an overall tractional resistance (GFW) and/or an at least almost constant pedal position is detected.

5. Method according to any one of claims 1 to 4, characterized in that the upshift block (FFO=1) is lifted when during detected traction operation a negative pedal gradient threshold (KW_PSTGNEG) is underrun and then overrun.

7. Method according to any one of claims 1 to 5, characterized in that after detection of a spontaneous gas/pedal release (FastOff) and a subsequent coasting operation, a change is made form a mode “

wait for exit”

to a mode “

prepare exit”

when the actual pedal position value (PST) is higher than the pedal position value (PST2) at the moment of the spontaneous gas/pedal release (FastOff) plus an offset value (KW_PSTO2).

9. Method according to at least one of the preceding claims, characterized in that the upshift block (FFO=1) remains active when the vehicle acceleration/deceleration (AIST) is lower than a threshold (KL_AFZF) stored depending on the overall tractional resistance (GFW) while a positive pedal position gradient threshold (KW_PSTGPOS) is exceeded.

10. Method according to claim 9, characterized in that in the mode “

prepare exit”

a branching off is made when the pedal gradient (PSTG) again falls below the positive pedal gradient threshold (KW_PSTGPOS).

11. Method according to at least one of the preceding claims, characterized in that the upshift block (FFO=1) remains active when the vehicle acceleration/deceleration (AIST) is lower than the threshold (KL_AFZG) stored depending on the overall tractional resistance (GFW) while a negative pedal gradient threshold (KW_PSTGNEG) is underrun, the mode of the upshift block (FFO=1) being left when the negative pedal gradient threshold (KW_PSTGNEG) is exceeded.

12. Method according to at least one of the preceding claims, characterized in that the positive and/or the negative pedal position gradient threshold (KW_PSTGPOS, LW_PSTGNET) is determined depending on the pedal position (PST) and the driver-type evaluation meter COUNT.

13. Method according to at least one of the preceding claims, characterized in that the pedal gradient threshold (KF-PSTG) is stored in a characteristic field as function of a pedal position value (PST) and of a driver-type evaluation meter COUNT.

14. Method according to at least one of the preceding claims, characterized in that the quantities of the driver-type evaluation meter (COUNT) are determined in a program module of the electronic transmission control for evaluation of the driving behavior.

15. Method according to at least one of the preceding claims, characterized in that the mode of the upshift block (FFO=1) is deactivated when the maximum engine rotational speed (NMO_MAX) has been exceeded.

6. Method according to any one of clams 1 to 5, characterized in that after detection of a spontaneous gas/pedal release (FastOff) and of a subsequent coasting operation, a change is made from a mode “

wait for exit”

to a mode “

prepare exit”

when traction operation is detected by the actual engine torque (MMM) being upon or above the push-pull characteristic line (KL_ZS) depending on the engine rotational speed (NMO) plus an offset value (KW_ZSO).

8. Method according to claim 6 or 7, characterized in that a return is made form the mode “

prepare exit”

to the mode “

wait for exit”

when a coasting operation is again detected by the actual engine torque (MMM) lying below the push-pull line (KL_ZS) when the upshift block (FFO=1) is activated.