Method and system for engine speed control

Patent metadata

Field	Value
Publication number	US-9850831-B2
Application number	US-201514927070-A
Country	US
Kind code	B2
Filing date	Oct 29, 2015
Priority date	Oct 29, 2015
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

Methods and systems are provided for engine speed flare control in an engine system having multiple staged charge boosting devices. In one example, during an engine start, an upstream compressor is rotated backwards via an electric motor to reduce the intake manifold pressure. The engine is then fueled based on the lower manifold pressure to reduce torque and engine speed flare until idle engine speed conditions are reached.

First claim

The invention claimed is:

1. A method for an engine, comprising:
during an engine run-up to idle speed:
spinning a first compressor with a motor opposite a normal direction to lower intake manifold pressure, wherein a speed of the first compressor spinning is based on engine speed, the first compressor being driven by an electric motor; while
not spinning a second compressor located downstream of the first compressor, the second compressor driven by an exhaust turbine via a shaft.

2. The method of claim 1 , wherein the spinning opposite the normal direction is reduced upon the engine reaching idle speed.

3. The method of claim 1 , further comprising, in response to the engine reaching the idle speed, spinning the first compressor forward until a speed of the turbine is above a threshold turbine speed, and then decelerating the first compressor.

4. The method of claim 3 , wherein the spinning the first compressor opposite the normal direction includes selectively coupling the electric motor to a reversing circuit, and wherein the spinning the first compressor forward includes selectively decoupling the electric motor from the reversing circuit.

5. The method of claim 2 , wherein the speed of the first compressor spinning based on the engine speed includes increasing the speed of the first compressor spinning as the engine speed approaches or exceeds a threshold speed.

6. The method of claim 1 , further comprising, while spinning the first compressor opposite the normal direction, holding an intake throttle open and fueling engine cylinders based on the lower manifold pressure.

7. A method for a boosted engine, comprising:
during an engine start,
before engine speed reaches idling speed, spinning a first compressor opposite a normal direction with a second compressor deactivated; and
in response to the engine speed reaching idling speed, spinning the first compressor forward with the second compressor maintained deactivated,

wherein the first compressor is a supercharger compressor driven by an electric motor, and wherein the second compressor is a turbocharger compressor driven by an exhaust turbine via a shaft located downstream of the first compressor.

8. The method of claim 7 , wherein spinning the first compressor backwards includes spinning the first compressor at a speed based on engine speed relative to idling speed, and wherein spinning the first compressor forward includes spinning the first compressor at a speed based on a turbine speed of the exhaust turbine.

9. The method of claim 7 , further comprising, in response to the engine speed reaching idling speed, maintaining the second compressor deactivated while spinning the first compressor forward until a turbine speed of the exhaust turbine reaches a threshold speed.

10. The method of claim 9 , further comprising, in response to the turbine speed reaching the threshold speed, deactivating the first compressor and spinning the second compressor forward.

11. The method of claim 10 , wherein deactivating the first compressor and spinning the second compressor forward includes bypassing the first compressor and providing pressurized air to the engine via the second compressor.

12. The method of claim 11 , further comprising, in response to an increase in torque demand while spinning the second compressor forward, spinning the first compressor forward and providing pressurized air to the engine via each of the first and second compressors.

13. An engine system, comprising:
an engine having an intake manifold;
an intake throttle;
a pedal for receiving an operator torque demand;
a fuel injector coupled to an engine cylinder;
a first intake compressor driven by an electric motor, the motor powered by a battery;
a reversing circuit selectively couplable to the electric motor;
a second intake compressor driven by an exhaust turbine, the first compressor positioned upstream of the first compressor along an intake passage;
a pressure sensor coupled to the intake manifold; and
a controller with computer readable instructions stored on non-transitory memory for:
determining estimated manifold pressure; and
in response to an engine restart request,
rotating the first compressor opposite a normal direction via the motor to generate intake manifold vacuum; and
during the rotating the first compressor the opposite the normal direction, fueling the engine cylinder based on the estimated manifold pressure until an engine speed reaches a threshold speed.

14. The system of claim 13 , wherein the controller includes further instructions for: while rotating the first compressor backwards, holding the intake throttle open.

15. The system of claim 13 , wherein the controller includes further instructions for:
coupling the electric motor to the reversing circuit to spin the first compressor backwards; and
after the engine speed reaches the threshold speed, discontinuing rotation of the first compressor while continuing to fuel the engine cylinder based on the estimated manifold pressure.

16. The system of claim 15 , wherein the controller includes further instructions for:
in response to a pedal tip-in,
decoupling the electric motor from the reversing circuit and rotating the first compressor forward via the electric motor, without rotating the second compressor, until a turbine speed is higher than a threshold turbine speed; and
after the turbine speed is higher than the threshold turbine speed, decelerating the first compressor and rotating the second compressor via the turbine based on the operator torque demand.

17. The system of claim 16 , further comprising a bypass coupling an inlet of the first compressor to an outlet of the first compressor, the bypass including a bypass valve, wherein the controller includes further instructions for:
holding the bypass valve closed when rotating the first compressor backwards or forward; and
opening the bypass valve when decelerating the first compressor to provide pressurized air to the engine via only the second compressor.

Assignees

• Ford Global Tech Llc

Inventors

• Ossareh Hamid-Reza
• Banker Adam Nathan
• Xiao Baitao

Classifications

• F02D41/062

  for starting (F02D41/061 takes precedence) · CPC title

• F02D41/0007 Primary

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02D41/06

  for engine starting or warming up {(F02D41/0255 takes precedence)} · CPC title

• F02D2200/0402

  the parameter being determined by using a model of the engine intake or its components · CPC title

• F02B37/14

  {Control} of the alternation between {or the operation of} exhaust drive and other drive of a pump, e.g. dependent on speed · CPC title