Method and system for engine control

Patent metadata

Field	Value
Publication number	US-9873435-B2
Application number	US-201615146809-A
Country	US
Kind code	B2
Filing date	May 4, 2016
Priority date	May 4, 2016
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

Methods and systems are provided for integrating a bi-fuel engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain usage of a current fuel or transition to an alternate fuel based on the cost efficiency of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a fuel transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

First claim

The invention claimed is:

1. A method for a multi-fuel engine coupled with a continuously variable transmission (CVT), comprising:
for a power level, comparing engine cost efficiency with a current fuel to engine cost efficiency with an alternate fuel at an adjusted engine speed-load based on output of sensors of engine operating parameters; and
in response to a higher than threshold improvement in the cost efficiency with the alternate fuel at the adjusted engine speed-load, transitioning to the alternate fuel via a controller sending a signal to an actuator coupled to a fuel injector delivering the alternate fuel to a cylinder to activate the fuel injector and changing to the adjusted engine speed-load.

2. The method of claim 1 , further comprising, in response to a lower than threshold improvement in the cost efficiency, maintaining the current fuel, wherein the cost efficiency for a given fuel is a ratio of work generated by the given fuel relative to a monetary cost of using the given fuel.

3. The method of claim 2 , further comprising adjusting the engine speed-load while maintaining the current fuel, the adjusted engine speed-load with the current fuel different from the adjusted engine speed-load with the alternate fuel.

4. The method of claim 1 , wherein the adjusted engine speed-load with the alternate fuel is based on a knock limit of the engine when operating with the alternate fuel and wherein the adjusted engine speed-load with the current fuel is based on a knock limit of the engine when operating with the current fuel.

5. The method of claim 4 , wherein changing to the adjusted engine speed-load includes increasing engine speed while decreasing engine load to maintain the power level as engine operation with the alternate fuel approaches the knock limit.

6. The method of claim 4 , wherein changing to the adjusted engine speed-load includes decreasing engine speed while increasing engine load to maintain the power level as engine operation with the alternate fuel moves away from the knock limit.

7. The method of claim 1 , wherein changing to the adjusted engine speed-load includes selecting a CVT speed ratio matching the adjusted engine speed-load.

8. The method of claim 1 , wherein the power level is maintained at each of engine operation with the current fuel and engine operation with the alternate fuel with the adjusted engine speed-load.

9. The method of claim 1 , wherein the power level is a powertrain output of the engine determined as a product of engine load and engine speed.

10. The method of claim 1 , wherein the current fuel and the alternate fuel vary in one or more of an octane rating, an alcohol content, and a delivery mechanism via which they are delivered into an engine cylinder, wherein the delivery mechanism includes one of direct injection, port injection, and central injection.

11. The method of claim 10 , wherein the current fuel has a higher octane rating than the alternate fuel.

12. A method for an engine coupled with a continuously variable transmission (CVT), comprising:
for a driver demand determined based on output of a pedal position sensor coupled to an operator pedal,
estimating a first cost efficiency associated with maintaining a first fuel and a second cost efficiency associated with transitioning to a second fuel while operating with a knock-adjusted and friction-adjusted engine speed-load profile; and
in response to the second cost efficiency being higher than the first cost efficiency, transitioning to usage of the second fuel via a controller sending a signal to an actuator coupled to a fuel injector delivering the second fuel to a cylinder to activate the fuel injector and transitioning to the knock-adjusted and friction-adjusted engine speed-load profile via adjustments to a speed ratio of the CVT.

13. The method of claim 12 , wherein transitioning to the knock-adjusted and friction-adjusted engine speed-load profile includes transitioning from a default engine speed-load profile of the first fuel, and wherein an engine power output during engine operation with the first fuel is the same as an engine power output during engine operation with the second fuel with the knock-adjusted and friction-adjusted engine speed-load profile.

14. The method of claim 12 , further comprising, in response to the second cost efficiency being smaller than the first cost efficiency, maintaining usage of the first fuel and optionally transitioning to the knock-adjusted and friction-adjusted engine speed-load profile via adjustments to the speed ratio of the CVT.

15. The method of claim 14 , wherein the second fuel has a lower octane rating than the first fuel, and wherein the knock-adjusted and friction-adjusted engine speed-load profile includes a higher engine speed and a lower engine load compared to the first fuel.

16. The method of claim 14 , wherein the second fuel has a higher octane rating than the first fuel, and wherein the knock-adjusted and friction-adjusted engine speed-load profile includes a lower engine speed and a higher engine load compared to the first fuel.

17. A vehicle system, comprising:
an engine with a cylinder;
a first fuel injector for delivering a first fuel from a first fuel tank into the cylinder;
a second fuel injector for delivering a second fuel from a second fuel tank into the cylinder, the second fuel having a different alcohol content than the first fuel;
a continuously variable transmission (CVT) coupling the engine to vehicle wheels, the CVT having a plurality of speed ratios; and
a controller with computer readable instructions stored on non-transitory memory for:
estimating a first cost efficiency associated with maintaining usage of the first fuel and a second cost efficiency associated with transitioning to usage of the second fuel; and
if the second cost efficiency with a modified engine speed-load profile is higher than the first cost efficiency, activating the second fuel injector while deactivating the first fuel injector to transition to the second fuel while selecting one of the plurality of speed ratios of the CVT to provide the modified engine speed-load profile.

18. The system of claim 17 , wherein the controller includes further instructions for:
if the first cost efficiency is higher than the second cost efficiency, maintaining the first fuel injector activated and the second fuel injector deactivated to maintain engine operation with the first fuel.

19. The system of claim 17 , wherein the modified engine speed-load profile while using the second fuel is a first modified engine speed-load profile based on an engine knock limit and engine friction when operating with the second fuel.

20. The system of claim 17 , wherein the selecting includes selecting a first lower speed ratio of the CVT when the modified engine speed-load profile includes a higher engine speed and a lower engine load, and selecting a second higher ratio of the CVT when the modified engine speed-load profile includes a lower engine speed and a higher engine load.

Assignees

• Ford Global Tech Llc

Inventors

• Miller Kenneth James
• Leone Thomas G
• Martin Douglas Raymond

Classifications

• F02M43/04

  Injectors peculiar thereto · CPC title

• F02D2200/0611

  Fuel type, fuel composition or fuel quality · CPC title

• F02D19/061 Primary

  by controlling fuel injectors · CPC title

• B60W2710/10

  Change speed gearings · CPC title

• B60W30/1882 Primary

  characterised by the working point of the engine, e.g. by using engine output chart · CPC title