Method for controlling an engine of a hybrid powertrain in a fuel enrichment mode

• US 8,630,776 B2
• Filed: 10/20/2008
• Issued: 01/14/2014
• Est. Priority Date: 11/04/2007
• Status: Expired due to Fees

• Current Assignee: Bayerische Motoren Werke AG, Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Original Assignee: Bayerische Motoren Werke AG, GM Global Technology Operations LLC (General Motors Company), Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Inventors: Heap, Anthony H., Brunssen, Wilfried, Thompson, Scott J
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): MUSTAFA, IMRAN K
• Application Number:
  US12/254,534
• Publication Number:
  US 20090118939A1
• Time in Patent Office: 1,912 Days
• Field of Search: 701/54, 701/103
• US Class Current: 701/54
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/38 characterised by the driveline clutches shift clutches within the gearing or transmission B60K6/36 , B60K6/54
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• 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 10/26 for electrical energy, e.g. batteries or capacitors
• 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 2510/02 Clutches
• CPC Class Codes: B60W 2510/0619 Air-fuel ratio
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0622 Air-fuel ratio
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 2710/105 : Output torque
• CPC Class Codes: F16H 2037/0866 : Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
• CPC Class Codes: F16H 2037/102 : the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 : Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/106 : with switching means to provide two variator modes or ranges
• CPC Class Codes: F16H 3/728 : with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility

Abstract

An engine is coupled to an input member of a hybrid transmission. The hybrid transmission is operative to transfer torque between the input member and a torque machine and an output member to generate an output torque in response to an operator torque request. The torque machine is connected to an energy storage device. A method for controlling the engine includes monitoring the operator torque request, determining a maximum engine torque operating the engine at stoichiometry, determining a maximum motor torque output from the torque machine, determining a maximum output torque from the hybrid transmission when the torque machine is generating the maximum motor torque and the engine is generating the maximum engine torque operating at stoichiometry, and controlling the engine in a fuel enrichment mode when the operator torque request exceeds the maximum output torque from the hybrid transmission when the torque machine is generating the maximum motor torque and the engine is generating the maximum engine torque operating at stoichiometry.

Claims

1. Method for controlling an engine coupled to an input member of a hybrid transmission, the hybrid transmission operative to transfer torque between the input member and a torque machine and an output member to generate an output torque in response to an operator torque request, the torque machine connected to an energy storage device, the method comprising:

monitoring the operator torque request;

determining a maximum engine torque output from the engine to the output member while operating the engine at stoichiometry;

determining a maximum motor torque output from the torque machine to the output member;

determining a maximum output torque from the hybrid transmission when the torque machine is outputting the maximum motor torque to the output member and the engine is generating the maximum engine torque operating at stoichiometry to the output member;

determining a preferred engine torque comprising an engine torque minimizing total powertrain system costs in response to the operator torque request;

only when the operator torque request exceeds the maximum output torque from the hybrid transmission, determining a fuel enrichment torque for operating the engine;

determining a maximum engine torque constraint associated with a capacity of the hybrid transmission to transfer the engine torque;

limiting the fuel enrichment torque based upon the maximum engine torque constraint; and

controlling the engine in a fuel enrichment mode based upon the limited fuel enrichment torque for operating the engine at an air-fuel ratio rich of stoichiometry when the operator torque request exceeds the maximum output torque from the hybrid transmission when the torque machine is generating the maximum motor torque and the engine is generating the maximum engine torque operating at stoichiometry and when the fuel enrichment torque is greater than the preferred engine torque.

2. The method of claim 1, further comprising determining the fuel enrichment torque for operating the engine based upon the maximum engine torque operating the engine at stoichiometry and a ratio of the operator torque request and the maximum output torque.

3. The method of claim 2, further comprising controlling operation of the engine based upon the fuel enrichment torque.

4. The method of claim 1, further comprising determining the maximum motor torque output from the torque machine based on power limits of the energy storage device.

5. Method for controlling an engine coupled to an input member of a hybrid transmission, the hybrid transmission operative to transfer torque between the input member and first and second torque machines and an output member to generate an output torque in response to an operator torque request, the method comprising:

monitoring the operator torque request;

determining a maximum engine torque output from to the engine to the output member while operating the engine at stoichiometry;

determining maximum motor torques output from the first and second torque machines to the output member;

determining a maximum output torque from the hybrid transmission when the first and second torque machines are each outputting the maximum motor torques to the output member and the engine is generating the maximum engine torque operating at stoichiometry to the output member;

determining a maximum engine torque constraint associated with a capacity of the hybrid transmission to transfer torque between the input member and the first and second torque machines and the output member;

determining a preferred engine torque comprising an engine torque minimizing total powertrain system costs in response to the operator torque request;

only when the operator torque request exceeds the maximum output torque from the hybrid transmission, determining a fuel enrichment torque for operating the engine at an air-fuel ratio rich of stoichiometry;

constraining the fuel enrichment torque based upon the maximum engine torque constraint; and

controlling the engine based upon the constrained fuel enrichment torque only when the constrained fuel enrichment torque is greater than the preferred engine torque.

6. The method of claim 5, comprising controlling the engine based upon the constrained fuel enrichment torque when the operator torque request exceeds the maximum output torque from the hybrid transmission when the torque machine is generating the maximum output torque and the engine is generating the maximum engine torque operating at stoichiometry.

7. The method of claim 5, wherein constraining the fuel enrichment torque based upon the maximum engine torque constraint comprises limiting the fuel enrichment torque to the maximum engine torque constraint.

8. The method of claim 5, further comprising determining the fuel enrichment torque for operating the engine based upon the maximum engine torque operating the engine at stoichiometry and a ratio of the operator torque request and the maximum output torque.

9. Method for controlling an engine coupled to an input member of a hybrid transmission, the hybrid transmission operative to transfer torque between the input member and electric machines and an output member to generate an output torque in response to an operator torque request, the torque machine connected to an electrical energy storage device, the method comprising:

monitoring the operator torque request;

determining a maximum engine torque output from the engine to the output member while operating the engine at stoichiometry;

determining a maximum motor torque output from the electric machines to the output member based on power limits of the electrical energy storage device;

determining a maximum output torque from the hybrid transmission when the torque machines are outputting the maximum output torques to the output member and the engine is generating the maximum engine torque operating at stoichiometry to the output member;

determining a preferred engine torque comprising an engine torque minimizing total powertrain system costs in response to the operator torque request;

only when the operator torque request exceeds the maximum output torque from the hybrid transmission, determining a fuel enrichment torque for operating the engine;

determining a maximum engine torque constraint associated with a capacity of the hybrid transmission to transfer the engine torque;

constraining the fuel enrichment torque based upon the maximum engine torque constraint; and

only when the fuel enrichment torque is greater than the preferred engine torque, controlling the engine in a fuel enrichment mode for operating the engine at an air-fuel ratio rich of stoichiometry when the operator torque request exceeds the maximum output torque from the hybrid transmission when the torque machine is generating the maximum output torque and the engine is generating the maximum engine torque operating at stoichiometry and when the fuel enrichment torque is greater than the preferred engine torque.

10. The method of claim 9, further comprising determining the fuel enrichment torque for operating the engine based upon the maximum engine torque operating the engine at stoichiometry and a ratio of the operator torque request and the maximum output torque.

11. The method of claim 9, further comprising controlling operation of the engine based upon the limited fuel enrichment torque.