Altitude compensation system for controlling smoke emissions from a naturally aspirated railroad locomotive

Abstract

A railroad locomotive includes a naturally-aspirated reciprocating internal combustion engine, and a traction generator driven by the engine. A throttle position sensor produces a signal corresponding to the throttle position selected by the locomotive's operator. A load regulator receives a speed signal derived from the throttle position signal and outputs an excitation signal for the traction generator which is modified by a controller in response to air availability so that engine speed and load are controlled independently of the selected throttle position, so as to limit the exhaust smoke output of the engine.

1 . A rail vehicle, comprising:
 a naturally-aspirated, reciprocating internal combustion engine normally operated at a plurality of predetermined throttle positions corresponding to discrete engine speed and load points;   a traction generator driven by said engine;   a throttle position sensor for generating a throttle position signal corresponding to the throttle position selected by an operator;   a load regulator for receiving a speed signal derived from said throttle position signal, with the load regulator outputting an excitation signal for said traction generator; and   a controller for receiving at least said throttle position signal, said excitation signal, and an air availability signal, with said controller modifying said throttle position signal and said excitation signal in response to at least the value of said air availability signal, so that engine speed and load are controlled independently, based upon the selected throttle position, whereby the exhaust smoke output of the engine will be mitigated.   
     
     
         2 . A rail vehicle according to  claim 1 , wherein said engine comprises a four-stroke cycle diesel engine. 
     
     
         3 . A rail vehicle according to  claim 1 , wherein said engine comprises a blower-scavenged, two-stroke cycle diesel engine. 
     
     
         4 . A rail vehicle according to  claim 1 , further comprising an engine governor for controlling both said load regulator and a fuel supply system for said engine, with said governor controlling the amount of fuel being supplied to the engine in response to the modified throttle position signal and the modified excitation signal. 
     
     
         5 . A rail vehicle according to  claim 1 , wherein said air availability signal corresponds to ambient barometric pressure. 
     
     
         6 . A rail vehicle according to  claim 1 , wherein said engine comprises a blower scavenged two-stroke cycle engine and said air availability signal corresponds to air pressure within an airbox located within said engine. 
     
     
         7 . A rail vehicle, comprising:
 a naturally-aspirated, reciprocating internal combustion engine normally operated at a plurality of predetermined throttle positions corresponding to discrete engine speeds and air/fuel ratios;   a traction generator driven by said engine;   a throttle position sensor for generating a throttle position signal corresponding to the throttle position selected by an operator;   a load regulator for receiving said speed signal and for outputting an excitation signal for said traction generator; and   a controller for receiving at least said throttle position signal, said excitation signal, and an air availability signal, with said controller modifying said throttle position signal and said excitation signal in response to a decrease in air availability, so that engine speed and air fuel ratio are controlled independently of the selected throttle position, whereby the air/fuel ratio, and corresponding smoke output of the engine, may be reduced.   
     
     
         8 . A rail vehicle, comprising:
 a naturally-aspirated, reciprocating internal combustion engine normally operated at a plurality of predetermined throttle positions corresponding to discrete engine speeds and air/fuel ratios;   a throttle position sensor for generating a throttle position signal corresponding to the throttle position selected by an operator; and   a controller for receiving at least said throttle position signal and a signal indicative of air availability, with said controller acting to reduce an air/fuel ratio of the engine in operation, below an air/fuel ratio associated with the throttle position selected by the operator, when the air availability decreases below a threshold value.   
     
     
         9 . A method for modifying the air/fuel ratio control of a naturally aspirated reciprocating internal combustion engine powering a fraction generator in a rail vehicle having a manually settable throttle with a plurality of positions corresponding to predetermined engine speeds and engine loads, so as to control smoke caused by varying air availability, comprising:
 providing a single control module having an air availability sensing device and a throttle position monitor;   determining, by the control module, a desired engine speed and desired load, drawn from said predetermined engine speeds and loads, based upon the throttle setting and sensed air availability;   modifying, by the control module, a main generator excitation signal in response to the desired load; and   transmitting the modified excitation signal to the traction generator to control the engine load, while controlling the engine speed to the desired engine speed.