Method and system for exhaust catalyst warming

• US 9,784,199 B2
• Filed: 05/19/2017
• Issued: 10/10/2017
• Est. Priority Date: 02/04/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Glugla, Chris Paul
• Primary Examiner(s): Kwon, John
• Assistant Examiner(s): Hoang, Johnny H
• Application Number:
  US15/600,063
• Publication Number:
  US 20170254283A1
• Time in Patent Office: 144 Days
• Field of Search: 701101-105, 701110-113, 1233391, 12333911, 12333912
• CPC Class Codes: F01N 3/2006 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 Class Codes: F02D 2200/025 Engine noise, e.g. determined by using an acoustic sensor
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/024 to increase temperature of the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02P 5/1506 with particular means during starting
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for leveraging engine skip-fire operation during an engine cold-start to expedite catalyst heating. Based on the heat flux required, the engine may be operated with a group of cylinders selectively deactivated, with spark retard on remaining active cylinders increased, and with engine speed increased to reduce NVH issues during the skip-fire operation. The combination of parameters may be adjusted based on changes in exhaust temperature and NVH limits of the engine.

Claims

1. An engine system, comprising:

an engine including a plurality of cylinders;

an exhaust catalyst;

a temperature sensor coupled to an engine exhaust;

an accelerometer coupled to an engine block for estimating engine vibration;

electrically actuated cylinder valve mechanisms coupled to each of the plurality of cylinders;

a selectively deactivatable fuel injector coupled to each of the plurality of cylinders; and

an engine controller configured with computer readable instructions stored on non-transitory memory for;

during an engine cold-start,

estimating a heat flux required to activate the exhaust catalyst; and

based on the estimated heat flux,

deactivating individual cylinder valve mechanisms for one or more of the plurality of cylinders according to a pattern, the pattern including a total number of deactivated to active cylinders and an order of firing of active cylinders;

operating the active cylinders with an amount of spark retard based on the estimated heat flux and the pattern; and

adjusting an engine speed during the cold-start based on the pattern and the amount of spark retard.

2. The system of claim 1, wherein adjusting the engine speed includes increasing the engine speed as a number of active cylinders in the pattern decreases.

3. The system of claim 2, wherein the controller includes further instructions for:

in response to a vibration output of the accelerometer being higher than an NVH limit,

adjusting one or more of the pattern, the amount of spark retard, and the engine speed.

4. The system of claim 3, wherein adjusting the pattern includes one or more of adjusting a total number of deactivated to active cylinders in the pattern and adjusting an identity of deactivated cylinders while maintaining the total number of deactivated to active cylinders.

5. The system of claim 3, wherein the adjusting includes, reducing the engine speed while maintaining the amount of spark retard or reducing the amount of spark retard while maintaining the engine speed.

6. The system of claim 4, wherein the heat flux is estimated based on a difference between a temperature of the exhaust catalyst and an activation temperature, the heat flux increased as the difference increases.