Gear selection method for an automatic transmission for a traction phase after a coasting phase of a motor vehicle

• US 8,571,773 B2
• Filed: 06/13/2011
• Issued: 10/29/2013
• Est. Priority Date: 06/16/2010
• Status: Active Grant

• Current Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Original Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Inventors: Roth, Martin
• Primary Examiner(s): Cheung, Mary
• Assistant Examiner(s): Do, Truc M
• Application Number:
  US13/158,855
• Publication Number:
  US 20110313631A1
• Time in Patent Office: 869 Days
• Field of Search: 701/60, 701/67, 701/95, 701/80, 477/107, 477/115
• US Class Current: 701/60
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 2030/1809 Without torque flow between driveshaft and engine, e.g. with clutch disengaged or transmission in neutral
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/0652 Speed change rate
• CPC Class Codes: B60W 2510/105 Output torque
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/30 Driving style
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2556/10 Historical data
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/18072 Coasting
• 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 2059/186 Coasting
• CPC Class Codes: F16H 2059/663 Road slope
• CPC Class Codes: F16H 2061/0496 for low engine torque, e.g. during coasting, sailing or engine braking
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: Y02T 10/60 Other road transportation technologies with climate change mitigation effect

Abstract

Disclosed herein is a gear selection method and device for an automatic transmission for a traction phase (Z2) after a coasting phase (S) of a motor vehicle. According to the method, in a traction phase (Z1) before the coasting phase (S), a sliding average value of the rotational speed level (n) and/or of the traction force level (F_x) is formed depending on the particular velocity (v) and particular gradient (ST) and is taken into consideration for defining at least one gear choice of the automatic transmission for the traction phase (Z2) after the particular coasting phase (S).

Claims

1. A gear selection method for an automatic transmission for a traction phase (Z2) after a coasting phase (S) of a motor vehicle, comprising the steps of;

forming, with a computational device, a sliding average value of a rotational speed level (n) and/or of a traction force level (Fx) in a traction phase (Z1) before the coasting phase (S) depending on a particular velocity (v) and a particular gradient (ST),

storing, in a memory device, the sliding average value of a rotational speed level (n) and/or of a traction force level (Fx), and

defining, with a defining device, at least one gear choice of the automatic transmission for the traction phase (Z2) after the coasting phase (S) taking into consideration the sliding average value,

wherein a driver'"'"'s rotational speed requirement (Wn) is defined taking into consideration the sliding average value of the rotational speed level (n) for a current velocity (v′

) and a current gradient (ST′

) at the end of the coasting phase (S) and a corresponding first and second gear choice are defined on the basis thereof,

wherein the first gear choice corresponds to a rotational speed requirement (Wn) above the value determined by the sliding average, and

wherein the second gear choice corresponds to a rotational speed requirement (Wn) below the value determined by the sliding average.

2. The method as claimed in claim 1, wherein a driver'"'"'s rotational speed requirement (Wn) is defined taking into consideration the sliding average value of the rotational speed level (n) for a current velocity (v′

) and a current gradient (ST′

) at the end of the coasting phase (S) and a corresponding gear choice is defined on the basis thereof.

3. The method as claimed in claim 1, wherein a driver'"'"'s traction force requirement (WFx) is defined taking into consideration the sliding average value of the traction force level (F_x) for a current velocity (v′

) and a current gradient (ST′

) at the end of the coasting phase (S), wherein the traction force requirement (WFx) is converted into a corresponding rotational speed/engine torque requirement and a corresponding gear choice is defined on the basis thereof.

4. The method as claimed in claim 1, wherein a driver'"'"'s traction force requirement (WFx) is defined taking into consideration the sliding average value of the traction force level (F_x) for a current velocity (v′

) and a current gradient (ST′

) at the end of the coasting phase (S), wherein the traction force requirement (WFx) is converted into a corresponding rotational speed requirement and a corresponding first and second gear choice are defined on the basis thereof, wherein the first gear choice corresponds to a traction force requirement (WFx) above the value determined by the sliding average, and wherein the second gear choice corresponds to a traction force requirement (WFx) below the value determined by the sliding average.

5. The method as claimed in claim 1, wherein at the time of the end of a particular coasting phase (S), a determination of a current gas pedal actuating value and/or of a current gas pedal actuating gradient is carried out and the at least one defined gear choice is adapted depending thereon.

6. The method as claimed in claim 1, wherein the automatic transmission does not permit pre-engagement of the defined gear choice, and the gear choice is engaged at the end of the coasting phase (S), the rotational speed at the end of the coasting phase (S) is synchronized and subsequently a frictional connection is established.

7. The method as claimed in claim 1, wherein the automatic transmission permits pre-engagement of a single defined gear choice, and the gear choice is engaged during the coasting phase (S), the rotational speed at the end of the coasting phase (S) is synchronized and subsequently a frictional connection is established.

8. The method as claimed in claim 1, wherein the automatic transmission permits pre-engagement of two defined gear choices, and the first and second gear choices are engaged during the coasting phase (S), a gear from the first and second gear choices, which gear is prioritized in accordance with a predefined criterion, is defined at the end of the coasting phase (S) as a final gear choice, the rotational speed at the end of the coasting phase (S) is synchronized and subsequently a frictional connection is established.

9. The method as claimed in claim 8, wherein the higher gear of the first and second gear choices is defined at the end of the coasting phase (S) as the final gear choice.

10. The method as claimed in claim 1, wherein a time window (at) within which the sliding average value of the rotational speed level (n) and/or of the traction force level (F_x) is formed is variable depending on at least one driving parameter.

11. The method as claimed in claim 1, wherein selection of an engaged gear takes into consideration that shifting times differ in length.