Engine starting via electric turbocharger

Patent metadata

Field	Value
Publication number	US-10487789-B2
Application number	US-201715851637-A
Country	US
Kind code	B2
Filing date	Dec 21, 2017
Priority date	Dec 21, 2017
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

Methods and systems are provided for starting an engine via an electric turbocharger. In one example, a method for starting the engine via the electric turbocharger may include flowing compressed air from the electric turbocharger to cylinders of the engine to crank a crankshaft of the engine without a starter motor. The method may include adjusting an opening amount of electrically or pneumatically actuated intake valves and exhaust valves to reduce a force to crank the crankshaft.

First claim

The invention claimed is:

1. A method for an engine, comprising:
during an engine start request, driving a crankshaft of the engine in a normal, positive rotation direction without combustion only by flowing compressed air from an electrically driven air compressor to cylinders of the engine and without actuating a starter motor coupled to the crankshaft.

2. The method of claim 1 , wherein the electrically driven air compressor is part of an electric turbocharger and the flowing of compressed air from the electric turbocharger includes energizing an electric motor of the electric turbocharger in response to the engine start request to spin the air compressor of the electric turbocharger.

3. The method of claim 1 , wherein the electrically driven air compressor is part of an electric turbocharger and the flowing of compressed air from the electric turbocharger includes increasing a pressure of the compressed air above a threshold pressure by spinning the air compressor of the electric turbocharger.

4. The method of claim 3 , wherein the threshold pressure is greater than 2 atm.

5. The method of claim 3 , wherein the pressure of the compressed air is first increased above the threshold pressure within an intake passage upstream of a throttle of the engine; then, the throttle is opened to flow the compressed air to the cylinders.

6. The method of claim 3 , wherein the pressure of the compressed air is first increased above the threshold pressure at an intake manifold of the engine; then, adjusting an intake valve of the cylinders from a fully closed position to an opened position to flow the compressed air to the cylinders.

7. The method of claim 6 , further comprising determining a position of each piston disposed within each cylinder of the cylinders, and adjusting the intake valve based on the determined position of each piston.

8. The method of claim 1 , further comprising: after a duration of driving the crankshaft of the engine in the normal, positive rotation direction without combustion only by flowing compressed air from the electrically driven air compressor to cylinders of the engine and without actuating the starter motor, injecting fuel into the cylinders, and combusting the fuel and compressed air within the cylinders.

9. The method of claim 8 , wherein the duration is based on a rotation speed of the crankshaft exceeding a threshold rotation speed.

10. The method of claim 8 , wherein the duration is based on a number of complete rotations of the crankshaft exceeding a threshold number of complete rotations following the engine start request.

11. The method of claim 8 , wherein fuel and air are not combusted within the cylinders throughout the entire duration of driving the crankshaft in the normal, positive rotation direction only by flowing compressed air from the electrically driven air compressor to the cylinders.

12. The method of claim 8 , further comprising reducing engine speed following the duration via a speed reduction routine stored in a non-transitory memory of an electronic controller of the engine.

13. The method of claim 12 , wherein the speed reduction routine includes one of increasing an amount of opening of an electric turbocharger bypass valve coupled in parallel with the air compressor, adjusting an opening time of an intake valve and/or exhaust valve of the cylinders, or adjusting an ignition timing of the cylinders.

14. A method for an engine, comprising:
in response to an engine start request, flowing compressed intake air to engine cylinders from a compressor of an electric turbocharger and driving pistons disposed within the engine cylinders in a direction corresponding to a normal, positive rotation of a crankshaft coupled to the pistons via only the compressed intake air for a duration, with an amount of opening of intake valves and exhaust valves coupled to the engine cylinders being adjusted throughout the duration via cams of camshafts; and
transitioning from driving the pistons via only the compressed intake air to driving the pistons via combustion of fuel and air by initiating combustion within the engine cylinders following the duration.

15. The method of claim 14 , further comprising, prior to the engine start request and responsive to an engine shutdown event immediately prior to the engine start request with no other engine shutdown event or engine start request between, adjusting ignition timing of the engine to position a first piston at a top dead center position on engine shutdown, with a first intake valve coupled to a first cylinder including the first piston being in a fully opened position.

16. The method of claim 14 , wherein the duration spans at least 720 degrees of rotation of the crankshaft.

17. A method for an engine, comprising:
responsive to an engine start request:
flowing compressed air into cylinders of a first cylinder group to drive a crankshaft of the engine in a normal, positive rotation direction via only the compressed air, the cylinders of the first cylinder group including a first plurality of intake valves and a first plurality of exhaust valves, with each intake valve of the first plurality of intake valves being in an opened position and with each exhaust valve of the first plurality of exhaust valves being in a fully closed position; and
while flowing compressed air into the cylinders of the first cylinder group to drive the crankshaft in the normal, positive rotation direction, maintaining a gas pressure within cylinders of a second cylinder group at atmospheric air pressure, the cylinders of the second cylinder group including a second plurality of intake valves and a second plurality of exhaust valves, with each intake valve of the second plurality of intake valves being in a fully closed position and each exhaust valve of the second plurality of exhaust valves being in an opened position.

18. The method of claim 17 , further comprising: prior to flowing compressed air into the cylinders of the first cylinder group to drive the crankshaft in the normal, positive rotation direction and during the engine start request, increasing an amount of opening of an intake valve of the first plurality of intake valves via an electronic controller of the engine.

19. The method of claim 17 , further comprising: prior to flowing compressed air into the cylinders of the first cylinder group to drive the crankshaft in the normal, positive rotation direction and during the engine start request, increasing an amount of opening of an exhaust valve of the second plurality of exhaust valves via an electronic controller of the engine.

20. The method of claim 17 , wherein flowing compressed air into cylinders of the first cylinder group responsive to the engine start request drives pistons disposed within the cylinders of the first cylinder group toward a bottom-dead-center position and drives pistons disposed within the cylinders of the second cylinder group toward a top-dead-center position, with the gas pressure within the cylinders of the second cylinder group being maintained at atmospheric air pressure as the pistons disposed within the cylinders of the second cylinder group are driven toward the top-dead-center position.

Assignees

• Ford Global Tech Llc

Inventors

• Money Eric

Classifications

• F02D41/0007

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

• F02N9/04 Primary

  the pressure fluid being generated otherwise, e.g. by compressing air · CPC title

• F02D41/26

  using computer, e.g. microprocessor · CPC title

• F02B39/10

  electric · CPC title

• F02D41/062

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