US 6,273,076 B1 · Optimized lambda and compression temperature control for compression ignition engines

Abstract

The performance of a compression ignition internal combustion engine is improved by optimizing excess air ratio (lambda) and/or intake air charge temperature (ACT) on a full time, full range basis. The basic procedure is to first determine the desired or optimum lambda and then to control ACT and intake manifold absolute pressure (MAP) to maintain them at the optimum values for the fuel quantity required at a particular operating point. This approach allows control of both temperature and pressure of the air entering the engine. Full range control requires that lambda and ACT be controlled both upward and downward to achieve optimal engine performance. Control of both lambda and ACT is further enhanced through the use of a supercharger with adjustable input power installed in series with a standard turbocharger compressor of the engine. Supercharger control may if desired be supplemented with turbo air bypass (TAB) control, turbocharger variable area nozzle or wastegate, turboexpander control, and intake and exhaust valve control including skip fire of both fuel and air. The essence of optimized lambda control is to measure the physical properties of the working fluid in the intake manifold, exhaust manifold, or both, compute the actual value of lambda, and compare that actual value with an optimum value for the prevailing engine operating conditions. This comparison yields an error signal which is then used to control the magnitude of the required adjustment in turbocharger pressure or other engine operating parameter.

Claims47

Dependent claims

A method of optimizing excess air ratio (lambda) in a liquid-fueled compression ignition engine, comprising:

(A) monitoring operation of said engine;
(B) determining an optimum lambda for optimizing at least one of a plurality of engine performance characteristics at prevailing engine speed and load conditions, said optimal lambda varying in response to different engine speed and load conditions and the at least one of the plurality of engine performance characteristics;
and
(C) automatically adjusting at least one engine operating parameter so as to cause the actual lambda to selectively increase and decrease to approach the optimum lambda at the prevailing speed and load conditions.

1 more element

A method of optimizing performance of a compression ignition engine, comprising the steps of:

(A) monitoring engine operation to obtain an indication of prevailing engine operating conditions;
(B) determining, based upon prevailing engine operating conditions, optimum values of excess air ratio (lambda) and air charge temperature (ACT) required to optimize an engine performance characteristic;
(C) determining the actual lambda and the actual ACT;
(D) comparing the actual lambda and the actual ACT to the optimal lambda and the optimal ACT and, if necessary to cause the actual lambda and the actual ACT to approach the desired lambda and the desired ACT, selectively and automatically
(1) increasing lambda by increasing the pressure of a turbocharger of said engine by adjusting the operation of a supercharger which is located in series with the turbocharger,
(2) decreasing lambda by decreasing the pressure of the turbocharger by adjusting the operation of the supercharger,
(3) increasing ACT by at least one o
(a) recirculating air from an outlet of a compressor of said turbocharger, through a supercharger, and back to an inlet of said compressor of said turbocharger prior to inducting the recirculated air into an intake manifold of said engine,
(b) decreasing a percentage of total intake airflow through an intercooler located downstream of said turbocharger, and
(c) decreasing a percentage of intake air flowing through an aftercooler and an expansion turbine located downstream of said intercooler, and,
(4) decreasing ACT by at least one of
(a) increasing the pressure of the turbocharger by adjusting the operation of the supercharger,
(b) increasing the percentage of total intake airflow through the intercooler, and
(c) increasing the percentage of intake air flowing through said aftercooler and said expansion turbine;
and
for so long as said engine is operating, repeating steps (A) through (D) in a closed loop routine so as to obtain and maintain optimum values of ACT and lambda at prevailing engine operating conditions.

13 more elements

A compression ignition internal combustion engine comprising:

(A) a plurality of cylinders each having an intake port and exhaust port;
(B) a fuel supply system which selectively supplies a fuel to said cylinders, wherein said fuel is one which ignites by compression;
(C) an air supply system which supplies air to said intake ports of said cylinders;
and
(D) electronic control means for controlling operation of at least one of said air supply system and said fuel supply system to:
(1) monitor operation of said engine;
(2) determine an optimum lambda for optimizing a selected engine performance characteristic at a prevailing engine operating condition the optimal lambda varying with engine operating conditions;
and
(3) automatically adjust at least one engine operating parameter so as to cause the actual lambda to selectively increase and decrease to approach the optimum lambda;
and
(4) repeat operations (1) through (3) on a full time, a full range basis;
(E) electronic control means for controlling operation of at least one of said air supply system and said fuel supply system to:
(1) monitor operation of said engine;
(2) determine an optimum lambda for optimizing a selected engine performance characteristic at a prevailing engine operating condition;
and
(3) automatically adjust at least one engine operating parameter so as to cause the actual lambda to selectively increase and decrease to approach the optimum lambda;
and
(E) a turbocharger having an air outlet in fluid communication with the intake ports of the cylinders and having an air inlet;
(F) a supercharger having an air outlet in fluid communication with said air inlet of said turbocharger and having an air inlet;
and
(G) a control device which is coupled to said electronic control means and which selectively controls operation of said supercharger.

18 more elements

A compression ignition internal combustion engine comprising:

(A) a plurality of cylinders each having an intake port and exhaust port;
(B) a fuel supply system which selectively supplies a fuel to said cylinders, wherein said fuel is one which ignites by compression;
(C) an air supply system which supplies air to said intake ports of said cylinders;
and
(D) electronic control means for controlling operation of at least one of said air supply system and said fuel supply system to
(1) monitor engine operation to obtain an indication of prevailing engine operating conditions,
(2) determine an optimum ACT for optimizing a selected engine performance characteristic at a prevailing engine operating condition, and
(3) automatically adjust at least one engine operating parameter so as to cause the actual ACT to approach the optimum ACT.

5 more elements

Dependencies are inferred from the claim text.

Optimized lambda and compression temperature control for compression ignition engines

Life of this patent

Optimized lambda and compression temperature control for compression ignition engines

Life of this patent

Abstract

Claims47