Apparatus and method for retrofit engine start/stop and idle control

Abstract

A retrofit engine start/stop control system includes a programmable logic controller, an engine block temperature sensor to measure an external engine temperature, an ambient temperature sensor, an ignition circuit connector, a battery voltage sensor and an engine speed sensor. The programmable logic controller includes computer executable instructions to start the engine when at least one of an external engine block temperature, an ambient air temperature and a battery output voltage fall below a predefined threshold value for startup. A related method for retrofit engine start/stop idle control includes activating a programmable logic controller to control stop and start and idle control functions of an internal combustion engine; measuring an engine block temperature, ambient temperature, and battery system voltage; determining if all of the monitored values exceed corresponding predetermined threshold values for shutdown; and shutting down the engine if all of the monitored values exceed corresponding predetermined threshold values.

What is claimed is: 
     
         1 . A retrofit engine start/stop control system comprising:
 a programmable logic controller comprising computer executable instructions for control stop and start functions of an internal combustion engine;   an engine block temperature sensor operable to directly measure an external temperature of an internal combustion engine;   an ambient air temperature sensor operable to measure the ambient air temperature outside an engine compartment;   an ignition circuit connector operable to energize an ignition circuit of an internal combustion engine to initiate starting of the engine;   a battery voltage sensor operable to measure the output voltage of an alternator and/or starter battery for the engine; and   an engine speed sensor operable to measure the rotational speed of the engine (RPM);   wherein, the computer executable instructions comprise instructions to initiate starting of the internal combustion engine when at least one of an external engine block temperature, an ambient air temperature and a battery output voltage fall below a predefined threshold value for startup.   
     
     
         2 . The retrofit engine start/stop control system of  claim 1 , wherein computer executable instructions further comprises computer executable instructions to initiate shutdown of the internal combustion engine when at least one of the external engine block temperature, the ambient temperature and the battery output voltage rise above the predefined threshold value for shutdown. 
     
     
         3 . The retrofit engine start/stop control system of  claim 1 , wherein the programmable logic controller further comprises a removable data storage medium which is operable to periodically record system status information, including one or more of the engine block temperature, the ambient temperature, the battery output voltage and an engine speed. 
     
     
         4 . The retrofit engine start/stop control system of  claim 3 , wherein the data storage medium further comprises one or more of an internal or removable memory card, chip, or suitable storage memory. 
     
     
         5 . The retrofit engine start/stop control system of  claim 1 , wherein the programmable logic controller is communicably and operably connected to an engine electrical system for enabling measurement of an output voltage of the electrical system and to detect a position of an ignition switch. 
     
     
         6 . The retrofit engine start/stop control system of  claim 1 , wherein the programmable logic controller is operably connected to a fast idle switch for providing control of an idle rate or idle engine speed during operation of the start/stop control system. 
     
     
         7 . The retrofit engine start/stop control system of  claim 6 , wherein the fast idle switch is operably connected to a fast idle throttle position sensor for detecting a throttle position of the internal combustion engine during fast idle. 
     
     
         8 . The retrofit engine start/stop control system of  claim 1 , wherein the engine block temperature sensor is adapted for attachment to an outside of the internal combustion engine. 
     
     
         9 . The retrofit engine start/stop control system of  claim 1  further comprising a coolant heater communicably connected to the programmable logic controller to provide initial heating or preheating of the internal combustion engine. 
     
     
         10 . A method for retrofit engine start/stop idle control, comprising:
 determining if an internal combustion engine is running;   activating a programmable logic controller adapted for controlling start/stop and idle control functions of the internal combustion engine;   measuring at least one of an engine block temperature, ambient temperature, and battery system voltage;   determining if any one of the measured engine block temperature, ambient temperature, and battery system voltage values exceed a corresponding predetermined threshold value; and   controlling a rate of the engine speed.   
     
     
         11 . The method of  claim 10 , wherein if the internal combustion engine is not running, initiating startup of the internal combustion engine. 
     
     
         12 . The method of  claim 11  further comprising controlling engine idle during warmup of the internal combustion engine. 
     
     
         13 . The method of  claim 10 , wherein if the internal combustion engine is running, the step of determining if any one of the measured values exceed or falls below a corresponding predetermined threshold value further comprises:
 determining if any one of the measured values exceed or falls below a corresponding predetermined threshold value for continued running of the internal combustion engine or shut down of the internal combustion engine, and   controlling an idle rate or idle engine speed.   
     
     
         14 . The method of  claim 13 , wherein if any of the measured values falls below a predetermined threshold value, the step of controlling the idle engine speed further comprises advancing an engine throttle to continue running the internal combustion engine. 
     
     
         15 . The method of  claim 14 , wherein advancing the engine throttle further comprises controlling a fast idle switch. 
     
     
         16 . The method of  claim 13 , wherein if any of the measured values exceed a corresponding threshold value for shut down, initiating shut down of the internal combustion engine. 
     
     
         17 . The method of  claim 16 , wherein initiating shut down of the internal combustion engine further comprises deactivating an ignition switch or an ignition connection. 
     
     
         18 . The method of  claim 13  further comprising the step of determining and ensuring that the internal combustion engine is running normally prior to activating the programmable logic controller. 
     
     
         19 . The method of  claim 18  further comprising the step of checking the idle engine speed to determine if the idle engine speed is within a predetermined range and the programmable logic controller is ready for activation. 
     
     
         20 . The method of  claim 18 , further comprising checking one or more sensors to determine if the internal combustion engine is running normally prior to activating the programmable logic controller.