Method and system to improve cold-start catalyst light-off

Patent metadata

Field	Value
Publication number	US-10138781-B2
Application number	US-201615255057-A
Country	US
Kind code	B2
Filing date	Sep 1, 2016
Priority date	Sep 1, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

Methods and systems are provided for expediting light-off of a catalyst during engine cold-start conditions by inhibiting rotation of the turbocharger shaft. In one example, a method may include inhibiting rotation of the turbocharger shaft during engine cold-start conditions until the catalyst is operating at a desired efficiency. The rotation of the shaft may be inhibited via either a passive or an active shaft locking mechanism.

First claim

The invention claimed is:

1. A turbocharger system, comprising:
a shaft rotationally coupled to a turbine and a compressor; and
a shaft locking mechanism that inhibits movement of the shaft responsive to engine cold-start conditions, wherein the shaft locking mechanism is a passive shaft locking mechanism, and wherein the passive shaft locking mechanism includes a phase-transitioning material that surrounds the shaft and is within recesses of the shaft.

2. The system of claim 1 , wherein the passive shaft locking mechanism inhibits movement of the shaft via solidification of the phase-transitioning material.

3. A method for expediting catalyst light-off, comprising:
determining engine operating conditions;
responsive to a first set of the engine operating conditions including cold-start conditions of the engine, inhibiting movement of a shaft of a turbocharger via a shaft locking mechanism controlled by an electronic controller of the engine, the shaft being coupled to a turbine rotor which is positioned in an exhaust stream of the engine; and
if a turbine inlet pressure is greater than a threshold pressure, enabling movement of the shaft, even during the cold-start conditions of the engine.

4. The method of claim 3 , further comprising responsive to a first set of engine operating conditions, enabling movement of the shaft.

5. The method of claim 4 , wherein the first set of engine operating conditions includes a viscosity of turbocharger bearing oil that is less than a threshold viscosity.

6. The method of claim 4 , wherein the first set of engine operating conditions includes a catalyst temperature that is greater than a threshold temperature.

7. The method of claim 3 , further comprising, responsive to degradation of the shaft locking mechanism, adjusting a waste-gate position.

8. The method of claim 7 , wherein degradation of the shaft locking mechanism includes the shaft locking mechanism being stuck in a locked state, and wherein the waste-gate position is adjusted to an open position responsive to the shaft locking mechanism being stuck in the locked state.

9. The method of claim 7 , wherein degradation of the shaft locking mechanism includes the shaft locking mechanism being stuck in an unlocked state, and wherein the waste-gate position is adjusted to an open position responsive to the shaft locking mechanism being stuck in the unlocked state until a temperature of a catalyst is greater than a threshold temperature.

10. The method of claim 9 , further comprising positioning the waste-gate responsive to a comparison of a desired engine boost and a current engine boost when the shaft locking mechanism is stuck in the unlocked state and the catalyst is greater than the threshold temperature.

11. A method for expediting catalyst light-off, comprising:
determining engine operating conditions;
responsive to a first set of engine operating conditions including cold-start conditions of an engine, inhibiting movement of a shaft of a turbocharger via a shaft locking mechanism controlled by an electronic controller of the engine, the shaft being coupled to a turbine rotor which is positioned in an exhaust stream of the engine; and
responsive to degradation of the shaft locking mechanism, adjusting a waste-gate position.

12. A method for expediting catalyst light-off, comprising:
determining engine operating conditions;
responsive to a first set of engine operating conditions including cold-start conditions of an engine, inhibiting movement of a shaft of a turbocharger via a shaft locking mechanism, the shaft being coupled to a turbine rotor which is positioned in an exhaust stream of the engine; and
responsive to degradation of the shaft locking mechanism, adjusting a waste-gate position, wherein the shaft locking mechanism is an active shaft locking mechanism controlled by an electronic controller of the engine.

13. The method of claim 12 , wherein the active shaft locking mechanism includes a pin that fits within a slot of the shaft.

14. The method of claim 13 , wherein the pin of the active shaft locking mechanism is positioned within the slot of the shaft to inhibit movement of the shaft.

Assignees

• Ford Global Tech Llc

Inventors

• Host Ray
• Wade Robert Andrew
• Morelli Anthony

Classifications

• F02B37/12 Primary

  Control of the pumps · CPC title

• F05B2220/40

  in turbochargers · CPC title

• F02B37/18

  by bypassing exhaust {from the inlet to the outlet of turbine or to the atmosphere} · CPC title

• F01N3/2006 Primary

  Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating (by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235) · CPC title

• F05D2220/40

  in turbochargers · CPC title