Shift point strategy for hybrid electric vehicle transmission

• US 7,463,962 B2
• Filed: 07/07/2005
• Issued: 12/09/2008
• Est. Priority Date: 07/07/2004
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Brackney, Larry J., Brunemann, George A.
• Primary Examiner(s): Keith; Jack W
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US11/176,409
• Publication Number:
  US 20060006008A1
• Time in Patent Office: 1,251 Days
• Field of Search: 701/51, 701/55, 701/56, 701/58, 701/60, 701/61, 180/65.6, 180/65.7, 192/3.51, 192/3.61, 903/902, 903/909, 903/917, 903/919, 903/945
• US Class Current: 701/55
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2061/0012 Transmission control for optimising power output of driveline
• CPC Class Codes: F16H 2061/022 Calculation or estimation of optimal gear ratio, e.g. best ratio for economy drive or performance according driver preference, or to optimise exhaust emissions
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/10 Controlling shift hysteresis
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration

Abstract

A method for determining a shift point strategy in a hybrid vehicle includes providing at least two power sources, selectively coupling the two or more power sources to a hybrid vehicle transmission, defining an input shaft speed for best acceleration, defining an input shaft speed for best fuel economy, determining driver intent compared to the best acceleration and the best fuel economy, and setting a shift point of the hybrid vehicle transmission based, at least in part, on the driver intent.

Claims

1. A method for determining a shift point strategy, comprising:

providing at least two power sources;

selectively coupling a hybrid vehicle transmission having an input shaft to said at least two power sources, said hybrid vehicle transmission receiving power from said power sources;

defining a speed of said transmission input shaft to promote an acceleration as compared to a fuel economy;

defining a speed of said transmission input shaft to promote said fuel economy as compared to said acceleration;

determining driver intent to promote either of said acceleration and said fuel economy; and

setting a shift point based, in part, on at least said determining step, wherein said shift point is variable based on said determining step; and

wherein said setting of said shift point comprises setting an unscheduled up shift point and an unscheduled downshift point for an engaged gear of said hybrid transmission; and

wherein said determining driver intent to promote either of said acceleration and said fuel economy includes assessing a gear position indication to promote one of said acceleration and said fuel economy.

2. The method as recited in claim 1, wherein said determining step comprises using driver demand torque as a fraction of total available torque.

3. The method as recited in claim 2, wherein said total available torque comprises a sum of available torque from said at least two power sources.

4. The method as recited in claim 1, further comprising:

determining an apparent inertia of a vehicle; and

using said determined vehicle apparent inertia as an indicator of a need to scale at least one shift point.

5. The method as recited in claim 4, wherein said determining an apparent inertia of a vehicle comprises:

measuring an output shaft torque of said hybrid vehicle transmission;

determining an acceleration of said vehicle; and

dividing said output shaft torque by said vehicle acceleration.

6. The method as recited in claim 1, further comprising the step of adding hysteresis after shifts to minimize a need for limit cycles.

7. The method as recited in claim 1, wherein said setting a shift point based in part on at least said determining step comprises setting an up shift point and a downshift point for each gear in said hybrid transmission.

8. A method for determining a shift point strategy, comprising:

providing at least a first power source and a second power source, wherein said first power source is an internal combustion engine;

selectively coupling a hybrid vehicle transmission having an input shaft to said at least two power sources, said hybrid vehicle transmission being configured to selectively receive power from said at least first and second power sources;

defining a speed of said transmission input shaft to promote an acceleration as compared to a fuel economy;

defining a speed of said transmission input shaft to promote said fuel economy as compared to said acceleration;

determining driver intent to promote either of said acceleration and said fuel economy, said driver intent being determined using driver demand torque as a fraction of total available torque, an apparent inertia of a vehicle, and a transmission gear position indication; and

setting a shift point based, in part, on at least said determining step, wherein said shift point is variable based on said determining step; and

wherein said setting of said shift point comprises setting an unscheduled up shift point and an unscheduled downshift point for an engaged gear of said hybrid transmission.

9. The method as recited in claim 8, further comprising adding hysteresis after shifts to minimize a need for limit cycles.

10. The method as recited in claim 8, wherein said setting a shift point based in part on at least said determining step comprises setting an up shift point and a downshift point for each gear in said hybrid transmission.

11. A method for operating a hybrid vehicle comprising:

establishing a shift point strategy, wherein said establishing a shift point strategy includes providing at least two power sources, selectively coupling a hybrid vehicle transmission having an input shaft to said at least two power sources, said hybrid vehicle transmission receiving power from at least one of said power sources, defining a speed of said transmission input shaft to promote an acceleration as compared to a fuel economy, defining a speed of said transmission input shaft to promote said fuel economy as compared to said acceleration, determining driver intent to promote either of said acceleration and said fuel economy, and setting a shift point based, in part, on at least said determining step, wherein said shift point is variable based on said determining step;

determining an intermediate gear that falls within said shift point strategy; and

selecting said intermediate gear;

wherein said determining driver intent to promote either of said acceleration and said fuel economy includes assessing a gear position indication to promote one of said acceleration and said fuel economy; and

wherein said setting of said shift point based, in part, on at least said determining step comprises setting an unscheduled up shift point and an unscheduled downshift point for an engaged gear of said hybrid transmission.

12. The method for operating a hybrid vehicle of claim 11, wherein said determining step comprises using driver demand torque as a fraction of total available torque.

13. The method for operating a hybrid vehicle of claim 12, wherein said total available torque comprises a sum of available torque from said at least two power sources.

14. The method for operating a hybrid vehicle of claim 11, further comprising:

determining an apparent inertia of a vehicle; and

using said determined vehicle apparent inertia as an indicator of a need to scale at least one shift point.

15. The method for operating a hybrid vehicle of claim 14, wherein said determining an apparent inertia of a vehicle comprises:

measuring an output shaft torque of said hybrid vehicle transmission;

determining an acceleration of said vehicle; and

dividing said output shaft torque by said vehicle acceleration.

16. The method for operating a hybrid vehicle of claim 11, further comprising the step of adding hysteresis after shifts to minimize a need for limit cycles.

17. The method for operating a hybrid vehicle of claim 11, wherein said setting a shift point based in part on at least said determining step comprises setting an up shift point and a downshift point for each gear in said hybrid transmission.

18. A system for determining a shift point strategy in a hybrid transmission having a plurality of prime movers selectively coupled to an input shaft comprising:

a control unit configured to define a speed of said hybrid transmission input shaft to promote an acceleration as compared to a fuel economy, define a speed of said transmission input shaft to promote said fuel economy as compared to said acceleration, determine driver intent to promote either of said acceleration and said fuel economy based in part at least on driver demand torque as a fraction of total available torque, and set a shift point based in part on at least said determining step, where said shift point is variable based on said determining step; and

wherein said shift point comprises an unscheduled up shift point and an unscheduled downshift point for an engaged gear of said hybrid transmission.

19. The system of claim 18, wherein said control unit is further configured to determine driver intent based at least in part on an automatic gear position indicator.

20. The system of claim 18, wherein said control unit is further configured to determine an apparent inertia of a vehicle, and use said determined vehicle apparent inertia as an indicator of a need to scale at least one shift point.