Method to improve fuel economy in lean burn engines with variable-displacement-like characteristics

• US 7,047,932 B2
• Filed: 05/12/2004
• Issued: 05/23/2006
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Surnilla, Gopichandra, Michelini, John Ottavio, Roth, John M.
• Primary Examiner(s): Yuen, Henry C.
• Assistant Examiner(s): Benton, Jason
• Application Number:
  US10/844,822
• Publication Number:
  US 20040206072A1
• Time in Patent Office: 741 Days
• Field of Search: 123/58.8, 123/568.12, 123/198.F, 123/568.11, 123/568.17, 123/568.18, 123/568.21
• US Class Current: 123/198.00F
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 3/0814 combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F02D 13/0215 changing the valve timing only
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 2250/21 during a transition between engine operation modes or states
• CPC Class Codes: F02D 2250/41 Control to generate negative pressure in the intake manifold, e.g. for fuel vapor purging or brake booster
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/0225 in relation with the gear ratio or shift lever position
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N
• CPC Class Codes: F02D 41/027 to purge or regenerate the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1475 Regulating the air fuel ratio at a value other than stoichiometry
• CPC Class Codes: F02D 41/3017 : characterised by the mode(s) being used
• CPC Class Codes: F02D 41/3029 : further comprising a homogeneous charge spark-ignited mode
• CPC Class Codes: F02D 41/307 : to avoid torque shocks

Abstract

A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

Claims

1. A method for operating and engine having a first and second group of cylinders coupled to one or more intake manifolds, comprising:

operating in a first mode with the first cylinder group operating with air and substantially no injected fuel and the second cylinder group operating by combusting air and fuel at a lean air-fuel ratio;

monitoring brake booster pressure in a brake booster coupled to one or more of the intake manifolds; and

during conditions of decreased brake booster pressure, disabling said first mode of operation and operating the engine in a second mode of operation wherein said second mode of operation comprises operating both first and second cylinder groups with a combusted air-fuel mixture.

2. The method of claim 1 wherein during at least a portion of said second mode of operation, said first and second cylinder groups are operated with said combusted air-fuel ratio about stoichiometry.

3. The method of claim 1 wherein during at least a portion of said second mode of operation, at least one of said first and second cylinder groups is operated with said combusted air-fuel ratio about stoichiometry.

4. The method of claim 1 wherein during at least a portion of said second mode of operation, at least one of said first and second cylinder groups is operated with said combusted air-fuel ratio lean of stoichiometry.

5. The method of claim 1 wherein during said transition, a position of a throttle in one or more of the intake manifolds is adjusted.

6. The method of claim 1 wherein during said transition, fuel injection is adjusted.