Annunciator with internal tachometer

Abstract

An annunciator device that utilizes a microprocessor allows for the inclusion of a tachometer or an hourmeter-tachometer, functions that typically require external instruments. A display circuit sequentially provides a digital readout indicative of a fault condition, engine speed and elapsed run time. The system draws sufficiently low current to be powered from a CD ignition or magnetic pickup power supply and backup battery. An annunciator device that allows for the inclusion of a tachometer, or a tachometer and an hourmeter, eliminates a great deal of cost by reducing instrument count, customer wiring, and overall instrument panel size.

We claim:  
     
       1. An annunciator for use with an internal combustion engine comprising: 
       (a) a sensor input unit in communication with a plurality of parallel connected sensor inputs which change state when a fault condition occurs;  
       (b) input means which a human can use to enter information;  
       (c) a common display means for sequentially displaying information, such as fault conditions and engine speed;  
       (d) a microprocessor-based logic unit which monitors said sensor input unit for a fault condition, monitors said input means for information entered by an operator, sequentially updates said display means, generates shutdown signals in response to said fault conditions, and measures engine speed in response to a tachometer signal, the frequency of which is indicative of the speed of the engine;  
       (e) shutdown means responsive to said shutdown signals generated by said microprocessor-based logic unit; said shutdown means being capable of shutting down the engine;  
       (f) a power supply which supplies power to said microprocessor-based logic unit and said sensor input unit only while  as long as the engine is running; and  
       (g) a backup battery that supplies power to at least said microprocessor-based logic unit while  as long as the engine is not running.  
     
     
       2. The annunciator device according to  claim 1 , wherein said power supply is a CD ignition power supply. 
     
     
       3. The annunciator device according to  claim 1 , wherein said power supply is a magnetic pickup power supply. 
     
     
       4. The annunciator device according to  claim 1 , wherein said microprocessor-based logic unit also measures engine run hours. 
     
     
       5. The annunciator device according to  claim 4 , wherein said power supply is a CD ignition power supply. 
     
     
       6. The annunciator device according to  claim 4 , wherein said power supply is a magnetic pickup power supply. 
     
     
       7. An annunciator for use with an engine, comprising: 
       ( a )  a sensor input unit to receive a plurality of sensor inputs;    
       ( b )  a keypad for user input;    
       ( c )  a liquid crystal display  ( LCD );  
       ( d )  a microprocessor programmed to monitor the sensor input unit for fault conditions indicated by the sensor inputs, generate shutdown signals in response to detecting said fault conditions, monitor the keypad for user input, calculate engine speed in response to a tachometer signal indicative of a speed of the engine, and display information on the LCD;    
       ( e )  output circuitry capable of shutting down the engine in response to the shutdown signals generated by the microprocessor;    
       ( f )  a power supply capable of receiving a capacitive discharge CD ignition signal to supply power to the annunciator only while the engine is running; and    
       ( g )  a backup battery that supplies power to the annunciator continuously while the engine is not running.   
     
     
       8. The annunciator of  claim 7 , wherein the LCD comprises a plurality of digits, each comprising seven segments. 
     
     
       9. The annunciator of  claim 8 , wherein the microprocessor is programmed to, while the engine is not running, display fault codes indicative of the cause of engine shutdown until a user presses a reset button on the keypad. 
     
     
       10. The annunciator of  claim 9 , wherein one type of fault code is a first number corresponding to an input of the sensor input unit. 
     
     
       11. The annunciator of  claim 8 , wherein the microprocessor is programmed to monitor engine run hours while the engine is running. 
     
     
       12. The annunciator of  claim 11 , wherein the microprocessor is programmed to sequentially display, on the LCD, information comprising: 
       
         fault codes;  
       
       
         engine speed; and  
       
       
         engine run hours. 
       
     
     
       13. The annunciator of  claim 7 , wherein the microprocessor is clocked by a crystal oscillator with a sufficiently low frequency such that the annunciator is capable of being powered from the CD ignition system while the engine is running and continuously from the backup battery while the engine is not running. 
     
     
       14. The annunciator of  claim 11 , wherein a frequency of the crystal oscillator is approximately  32 . 768  kilohertz. 
     
     
       15. The annunciator of  claim 7 , wherein a current draw of the microprocessor is approximately  50  microamperes. 
     
     
       16. The annunciator of  claim 7 , further comprising non- volatile memory and wherein the microprocessor is programmed to store configuration information in the non - volatile memory.   
     
     
       17. The annunciator of  claim 7 , wherein the microprocessor is programmed to generate shutdown signals in response to determining a calculated engine speed is equal to or greater than an overspeed setpoint value. 
     
     
       18. The annunciator of  claim 17 , wherein the microprocessor is programmed to display an overspeed fault code to indicate a calculated engine speed has exceeded the overspeed setpoint value, the overspeed fault code comprising a numeric value greater than a number of inputs of the sensor input unit. 
     
     
       19. The annunciator of  claim 17 , further comprising a circuit to generate a tachometer signal having a greater frequency than the CD ignition signal. 
     
     
       20. The annunciator of  claim 17 , wherein the microprocessor is programmed to calculate engine speed by counting pulses from the tachometer signal for a selected gate time. 
     
     
       21. A system for monitoring an engine having a capacitive discharge ( CD )  ignition system and/or equipment driven by the engine, the system comprising:    
       
         a plurality of sensors; and  
       
         a microprocessor - based annunciator with an internal tachometer in wired communication with the plurality of sensors, the annunciator capable of being powered from the CD ignition system while the engine is running and from a backup battery that supplies power to the annunciator continuously while the engine is not running.   
     
     
       22. The system of  claim 21 , wherein the plurality of sensors comprises a combination of normally open and normally closed switches. 
     
     
       23. The system of  claim 21 , wherein: 
       
         the annunciator comprises an LCD and a keypad; and  
       
       
         the annunciator displays a cause of engine shutdown on the LCD while the engine is not running until a user presses a button on the keypad. 
       
     
     
       24. The system of  claim 23 , wherein the LCD comprises a plurality of digits, each comprising seven segments. 
     
     
       25. A method for monitoring an engine with an annunciator, the engine having a CD ignition system, the method comprising: 
       
         operating a microprocessor of the annunciator at a sufficiently low frequency such that the annunciator is capable of being powered from the CD ignition system while the engine is running and from a backup battery while the engine is not running;  
       
       
         monitoring a plurality of sensors in wired communication with the annunciator;  
       
       
         calculating a speed of the engine with the microprocessor;  
       
       
         shutting down the engine in response to determining a fault condition; and  
       
         displaying a cause of the shutdown on a liquid crystal display  ( LCD )  until a user resets the shutdown.   
     
     
       26. The method of  claim 25 , wherein the LCD comprises a plurality of digits, each comprising seven segments. 
     
     
       27. The method of  claim 26 , wherein displaying a cause of the shutdown comprises: 
       
         displaying a first number corresponding to a monitored sensor to indicate the cause of shutdown is a faulted sensor; or  
       
       
         displaying a second number higher than the first number to indicate the cause of shutdown other than a faulted sensor. 
       
     
     
       28. The method of  claim 25 , wherein operating the microprocessor at a sufficiently low frequency such that the annunciator is capable of being powered from the CD ignition system while the engine is running and from a backup battery while the engine is not running comprises operating the microprocessor at approximately  32 . 768  kilohertz. 
     
     
       29. The method of  claim 25 , further comprising monitoring engine run hours while the engine is running. 
     
     
       30. The method of  claim 25 , further comprising storing engine run hours in non- volatile memory.   
     
     
       31. The method of  claim 25 , further comprising shutting the engine down in response determining the engine speed is equal to or greater than an overspeed setpoint. 
     
     
       32. The method of  claim 31 , further comprising multiplying a frequency of a CD ignition signal to generate the tachometer signal. 
     
     
       33. An annunciator for monitoring an engine having a capacitive discharge ( CD )  ignition system and/or equipment driven by the engine, the annunciator comprising:    
       
         an input unit for coupling with a plurality of sensors; and  
       
         a microprocessor - based logic unit including an internal tachometer function in communication with the input unit, the microprocessor - based logic unit capable of being powered from the CD ignition system as long as the engine is running and from a backup battery as long as the engine is not running.   
     
     
       34. The annunciator of  claim 33 , wherein the microprocessor- based logic unit is powered continuously from the backup battery as long as the engine is not running.   
     
     
       35. The annunciator of  claim 33 , wherein the input unit is capable of receiving a plurality of sensors that include a combination of normally open and normally closed switches. 
     
     
       36. The annunciator of  claim 33 , further comprising an LCD and a keypad, wherein the microprocessor- based logic unit is programmed to display a cause of engine shutdown on the LCD as long as the engine is not running until a user presses a button on the keypad.   
     
     
       37. The system of  claim 36 , wherein the LCD comprises a plurality of digits, each comprising seven segments.