Method for controlling shifting in a semi-automatic gear transmission

• US 9,085,293 B2
• Filed: 08/03/2011
• Issued: 07/21/2015
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Maier, Alexander, Wuerthner, Maik, Staudinger, Joachim, Kemler, Johannes
• Primary Examiner(s): Trammell, James
• Assistant Examiner(s): SMITH-STEWART, DEMETRA R
• Application Number:
  US13/825,402
• Publication Number:
  US 20130179045A1
• Time in Patent Office: 1,448 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: F16H 2059/366 Engine or motor speed
• CPC Class Codes: F16H 2059/663 Road slope
• CPC Class Codes: F16H 2061/0234 Adapting the ratios to special vehicle conditions
• CPC Class Codes: F16H 2061/0237 Selecting ratios for providing engine braking
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/21 Providing engine brake control

Abstract

A method of shift control for an automatic transmission of vehicle power train, having a permanent brake between a drive motor and a final drive, in which current vehicle-specific, road-specific and driver-specific operating parameters, topographical data relating to an upcoming stretch of road ahead of the vehicle are determined while driving, and from which a tractive resistance value for the upcoming stretch of road is determined, and control commands for thrust downshifts and/or upshifts are derived and implemented, within the transmission, during a thrust operation depending upon the tractive resistance value. This is achieved in that the maximum permanent braking force curves that are possible for the upcoming stretch of road, in the currently engaged gear, and each adjacent gear is determined based on the current traveling and engine speeds and analyzed to derive control commands for a thrust downshift and/or upshift in relation to the tractive resistance value.

Claims

1. A method of shift control for an automatic stepped variable speed transmission arranged positioned along a power train of a motor vehicle, which is provided with a permanent brake between a drive motor, designed as an internal combustion engine, and a final drive, the method comprising the steps of:

determining current vehicle-specific, road-specific and driver-specific operating parameters for the vehicle;

determining topographical data and an elevation profile, relating to a stretch of road that lies ahead of the vehicle while the vehicle is driving along the stretch of road;

determining from the topographical data, the elevation profile, and the operating parameters, a tractive resistance value (F_FW(x_F)) of the vehicle, for the stretch of road that lies ahead of the vehicle;

deriving and implementing control commands for at least one of thrust downshifts and thrust upshifts in an automatic mode of the stepped variable speed transmission, during a thrust operation, depending upon the tractive resistance value (F_FW(x_F));

determining maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) that are possible for the stretch of road that lies ahead of the vehicle in a currently engaged gear (G₀), and for each gear adjacent to the currently engaged gear, based on a current traveling speed (v_F(0)), a current engine speed (M_Mot(0)) and the tractive resistance value (F_FW(x_F)); and

analyzing the maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) to derive control commands for the at least one of the thrust downshift and the thrust upshift in relation to the tractive resistance value (F_FW(x_F)) for controlling operation of the stepped variable speed transmission.

2. The method according to claim 1, further comprising the step of only activating premature initiation and blocking of the at least one of the thrust downshift and the thrust upshift during a Bremsomat operation.

3. A method of shift control for an automatic stepped variable speed transmission arranged positioned along a power train of a motor vehicle, which is provided with a permanent brake between a drive motor, designed as an internal combustion engine, and a final drive, the method comprising the steps of:

determining current vehicle-specific, road-specific and driver-specific operating a parameters for the vehicle;

determining topographical data and an elevation profile, relating to a stretch of road that lies ahead of the a motor vehicle while the vehicle is driving along the stretch of road;

determining from the topographical data, the elevation profile, and the operating parameters, a tractive resistance value (F_FW(x_F)) of the vehicle, for the stretch of road that lies ahead of the vehicle;

deriving and implementing control commands for at least one of thrust downshifts and thrust upshifts in an automatic mode of the stepped variable speed transmission, during a thrust operation, depending upon the tractive resistance value (F_FW(x_F));

determining maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) that are possible for the stretch of road that lies ahead of the vehicle in a currently engaged gear (G₀), and for each gear adjacent to the currently engaged gear, based on a current traveling speed (v_F(0)), a current engine speed (M_Mot(0)) and the tractive resistance a value (F_FW(x_F));

analyzing the maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) to derive control commands for the at least one of the thrust downshift and the thrust upshift in relation to the tractive resistance value (F_FW(x_F)) for controlling operation of the stepped variable speed transmission; and

determining and evaluating the maximum permanent braking force curves (F<sub>Br—

max</sub>(G0), FBr_max(G₀−

1), F<sub>Br—

max</sub>(G₀−

2)) that are possible for the stretch of road that lies ahead of the vehicle in the currently engaged gear (G₀) and in specified number of lower gears (n_GR), in relation to the tractive resistance value (F_FW(x_F)), to derive the control commands for a thrust downshift.

4. The method according to claim 3, further comprising the step of prematurely initiating the thrust downshift when the maximum permanent braking force curve (F_Br—

_max(G₀)), for the currently engaged gear (G₀), exceeds the tractive resistance value (F_FW(x_F)) based on the current vehicle position (t=0, x_F=0) within either a specified first limit travel time (Δ

t_R1) or limit travel section (Δ

x_R1), and subsequently does not fall below the tractive resistance value (F_FW(x_F)) within either a specified second limit travel time (Δ

t_R2) or limit travel section (Δ

x_R2), and otherwise blocking the thrust downshift.

5. The method according to claim 4, further comprising the step of designating a highest possible respective low gear (G₀−

1, G₀−

2) as a target gear for the thrust downshift, for which the maximum permanent braking force curve (F<sub>Br—

max</sub>(G₀−

1), F<sub>Br—

max</sub>(G₀−

2)) does not exceed the tractive resistance value (F_FW(x_F)), after occurrence of a braking force deficiency in the currently engaged gear (G₀) within the second limit travel time (Δ

t_R2) or the limit travel section (Δ

x_R2).

6. The method according to claim 4, further comprising the step of designating a lowest of the respective low gears (G₀−

2) as a target gear for the thrust downshift, when the maximum permanent braking force curve (F<sub>Br—

max</sub>(x_F)) of this gear exceeds the tractive resistance value (F_FW(x_F)) after occurrence of a braking force deficiency in the currently engaged gear (G₀) within the second limit travel time (Δ

t_R2) or the limit travel section (Δ

x_R2).

7. The method according to claim 3, further comprising the step of replacing the current tractive resistance value (F_FW(0)), in order to prematurely initiate a thrust downshift, with either a tractive resistance value at a waypoint in front of the motor vehicle or an average tractive resistance value (F_FW(x_F)) over the route area in front of the motor vehicle, in which the maximum permanent braking force curve (F_Br—

_max(G₀)), for the currently engaged gear (G₀), lies above the tractive resistance value (F_FW(x_F)).

8. The method according to claim 3, further comprising the step of temporarily reducing a target speed (v_Soll) of a Bremsomat to initiate prematurely a thrust downshift during Bremsomat operation.

9. The method according to claim 3, further comprising the step of replacing the current tractive resistance value (F_FW(0)), to block a thrust downshift, with either a tractive resistance value at a waypoint in front of the motor vehicle, or an average tractive resistance value (F_FW(x_F)) over the route area in front of the motor vehicle, in which the maximum permanent braking force curve (F_Br—

_max(G₀)) for the currently engaged gear (G₀) lies below the tractive resistance value (F_FW(x_F)).

10. The method according to claim 3, further comprising the step of temporarily increasing a target speed (v_Soll) of a Bremsomat to block a thrust downshift during a Bremsomat operation.

11. The method according to claim 3, further comprising the step of initiating prematurely a thrust downshift within either the travel time or travel section until occurrence of a braking force deficiency in the currently engaged gear (G₀), and initiating prematurely a thrust upshift within either first limit travel time (Δ

t_H1) or limit travel route (Δ

x_H1).

12. The method according to claim 3, further comprising the step of firmly specifying the number of lower gears (n_GR) and the number of higher gears (n_GH), for which the maximum permanent braking force curves (F_Br—

_max(xF)) are determined.

13. The method according to claim 3, further comprising the step of determining, the number of lower gears (n_GR) and the number of higher gears (n_GH), for which the maximum permanent braking force curves (F_Br—

_max(x_F)), as the number of gears up to and including the lower or the higher gear respectively that are reached with the maximum allowable gear steps.

14. A method of shift control for an automatic stepped variable speed transmission arranged positioned along a power train of a motor vehicle, which is provided with a permanent brake between a drive motor, designed as an internal combustion engine, and a final drive, the method comprising the steps of:

determining current vehicle-specific, road-specific and driver-specific operating parameters for the vehicle;

determining topographical data and an elevation profile, relating to a stretch of road that lies ahead of the a motor vehicle while the vehicle is driving along the stretch of road;

determining from the topographical data, the elevation profile, and the operating parameters, a tractive resistance value (F_FW(x_F)) of the vehicle, for the stretch of road that lies ahead of the vehicle;

deriving and implementing control commands for at least one of thrust downshifts and thrust upshifts in an automatic mode of the stepped variable speed transmission, during a thrust operation, depending upon the tractive resistance value (F_FW(x_F));

determining maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) that are possible for the stretch of road that lies ahead of the vehicle in a currently engaged gear (G₀), and for each gear adjacent to the currently engaged gear, based on a current traveling speed (v_F(0)), a current engine speed (M_Mot(0)) and the tractive resistance value (F_FW(x_F));

analyzing the maximum permanent braking force curves (F<sub>Br—

max</sub>(x_F)) to derive control commands for the at least one of the thrust downshift and the thrust upshift in relation to the tractive resistance value (F_FW(x_F)) for controlling operation of the stepped variable speed transmission; and

determining and evaluating the maximum permanent braking force curves (F<sub>Br—

max</sub>(G₀+1), F<sub>Br—

max</sub>(G₀+2)) that are each possible for the stretch of road that lies ahead of the vehicle, for a specified number of higher gears higher gears (n_GH), in relation to the tractive resistance value (F_FW(x_F)) in order to derive control commands for the thrust upshift.

15. The method according to claim 14, further comprising the step of initiating prematurely a thrust upshift when the maximum permanent braking force curve (F_Br—

_max(G₀)), for the currently engaged gear (G₀), either is or falls below the tractive resistance value (F_FW(x_F)) based on the current vehicle position (t=0, x_F=0) within either a specified first limit travel time (Δ

t_H1) or limit travel section (Δ

x_H1), and when the maximum permanent braking force curve (F<sub>Br—

max</sub>(G₀+1), (F<sub>Br—

max</sub>(G₀+2)) of at least one higher gear (G₀+1, G₀+2) subsequently does not exceed the tractive resistance value (F_FW(x_F)) within either a specified second limit travel time (Δ

t_H2) or limit travel section (Δ

x_H2), and otherwise blocking a thrust upshift.

16. The method according to claim 15, further comprising the step of designating a highest possible gear of the higher gears (G₀+1, G₀+2) as a target gear for the thrust upshift, for which the maximum permanent braking force curve (F_Br—

_max(G₀+1), F<sub>Br—

max</sub>(G₀+2)) does not exceed the tractive resistance value (F_FW(x_F)), within either the second limit travel time (Δ

t_H2) or limit travel section (Δ

x_H2), and blocking a thrust upshift when this condition is not met by any of the higher gears (G₀+1, G₀+2).

17. The method according to claim 14, further comprising the step of replacing the current tractive resistance value (F_FW(0)), in order to initiate prematurely a thrust upshift, with either a tractive resistance value at a waypoint in front of the motor vehicle, or an average tractive resistance value (F_FW(x_F)) over the stretch of road the vehicle in which the maximum permanent braking force curve (F_Br—

_max(G₀)), for the currently engaged gear (G₀), lies below the tractive resistance value (F_FW(x_F)).

18. The method according to claim 14, further comprising the step of temporarily increasing a target speed (v_Soll) of a Bremsomat in order to initiate prematurely a thrust upshift during a Bremsomat operation.

19. The method according to claim 14, further comprising the step of replacing the current tractive resistance value (F_FW(0)), in order to block a thrust upshift, with either a tractive resistance value at a waypoint in front of the vehicle or an average tractive resistance value (F_FW(x_F)) over a route area in front of the vehicle, in which the maximum permanent braking force curve (F_Br—

_max(G₀)) for the currently engaged gear (G₀) lies above the curve of the tractive resistance (F_FW(x_F)).

20. The method according to claim 14, further comprising the step of temporarily reducing a target speed (v_Soll) of a Bremsomat in order to block a thrust upshift during a Bremsomat operation.