EGR control system and method for an internal combustion engine

• US 6,742,335 B2
• Filed: 07/11/2002
• Issued: 06/01/2004
• Est. Priority Date: 07/11/2002
• Status: Expired due to Fees

• Current Assignee: Clean Air Power, Inc. (Clean Air Power Ltd.)
• Original Assignee: Clean Air Power, Inc. (Clean Air Power Ltd.)
• Inventors: Wong, Hoi Ching, Gebert, Kresimir, Beck, N. John
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRIEU, THAI BA
• Application Number:
  US10/193,257
• Publication Number:
  US 20040006978A1
• Time in Patent Office: 691 Days
• Field of Search: 606/052, 602/95, 602/78, 602/98, 602/91, 123/568.17, 123/568.11, 123/568.12, 239/8, 239/403, 239/463, 239/468, 239/433, 239/265.11
• US Class Current: 60/605.2
• CPC Class Codes: F01N 3/021 by means of filters
• CPC Class Codes: F01N 3/043 without contact between liquid and exhaust gases
• CPC Class Codes: F02B 29/0406 Layout of the intake air cooling or coolant circuit
• CPC Class Codes: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: F02B 37/16 by bypassing charging air
• CPC Class Codes: F02M 26/06 Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
• CPC Class Codes: F02M 26/10 having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/19 Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
• CPC Class Codes: F02M 26/32 Liquid-cooled heat exchangers
• CPC Class Codes: F02M 26/35 with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

EGR mass fraction or a value indicative thereof can be calculated based on temperature measurements rather than mass flow and/or pressure measurements, hence negating the need for expensive and relatively unreliable measurement devices in an active EGR system for an internal combustion engine. The EGR system may be a low pressure EGR system configured to direct cooled, filtered EGR to the engine'"'"'s air intake system using an effective, simple venturi and/or a continuously regenerated catalytic particulate trap. The resultant system can reduce NOx emissions in a diesel engine on the order of 50% and approximately 90% for CO, HC, and PM. NOx and other emissions can be reduced still further when the EGR system is combined with other pretreatment and/or after treatment devices. Many components of the low pressure EGR system are also usable in a passive EGR system.

Claims

1. A method comprising:

(A) exhausting gases from an exhaust manifold of a compression ignition engine;

(B) separating a portion of said exhaust gases from the remainder of said exhaust gases under the control of an EGR valve;

(C) removing particulates from at least said portion of said exhaust gases using an actively regenerated catalytic particulate trap;

(D) cooling said portion of said exhaust gases;

then

(E) filtering said portion of said exhaust gases;

then

(F) mixing said portion of said exhaust gases with air in a venturi of an air induction system to form a mixture, said venturi generating a suction pressure of about 0.06 atmospheres and having a throat Mach Number of about 0.3 at an airflow rate through the venturi of about 60 lb/min.; and

(G) directing said mixture into an intake manifold of said engine;

(H) measuring

(1) a temperature of said portion of said exhaust gases after said portion is cooled,

(2) a temperature of said air, and

(3) a temperature of said mixture;

(I) calculating, based solely on the measuring step, a parameter indicative of a mass fraction of exhaust gases (mf_egr) in said mixture; and

(J) based on the calculating step, adjusting an EGR valve setting so as to adjust mf_egr to at least approach a desired mf_egr.

2. An engine comprising:

(A) an intake manifold;

(B) an exhaust manifold;

(C) an intake passage connected to said intake manifold;

(D) an exhaust passage connected to said exhaust manifold;

(E) an EGR line having an inlet connected to said exhaust passage and an outlet connected to said intake passage;

(F) a first temperature sensor that is configured to measure a temperature of exhaust gases in said EGR line;

(G) a second temperature sensor that is configured to measure air temperature;

(H) a third temperature sensor that is configured to measure a temperature of an air/gas mixture in a portion said intake passage downstream of said EGR line outlet;

(I) a controller that is connected to said first, second, and third temperature sensors and that is operable to,

(1) calculate, based on signals received from said first, second, and third temperature sensors, a parameter indicative of a mass fraction of exhaust gases (mf_egr) in said mixture; and

(2) adjust an engine operating parameter based on the calculation; and

(J) an exhaust gas cooler located in said EGR line, wherein said exhaust cooler comprises an exhaust gas passage having an inlet and an outlet, a coolant tube extending though said exhaust gas passage and having a first port connected to a source of liquid coolant and having a second port, and an annular coolant jacket having a first port connected to said second port of said coolant tube and having a second port connected to said source of liquid coolant.