Engine operation detecting circuit for a visual display

• US 6,377,168 B1
• Filed: 09/07/2000
• Issued: 04/23/2002
• Est. Priority Date: 09/07/2000
• Status: Active Grant

• Current Assignee: Delta Systems Inc.
• Original Assignee: Delta Systems Inc.
• Inventors: Harvey, Arthur James
• Primary Examiner(s): Lefkowitz, Edward
• Application Number:
  US09/656,578
• Time in Patent Office: 593 Days
• Field of Search: 340/438, 340/439, 340/441, 340/648, 123/406.56, 123/406.57
• US Class Current: 340/439
• CPC Class Codes: G07C 3/04 using counting means or digital clocks

Abstract

A timing circuit for providing an output to a microcontroller indicating whether an engine is operating, wherein the engine has a magneto. The circuit includes a triac coupled to the magneto for switching output generating circuitry between an engine on condition to an engine off condition in response to an operating condition of the engine. The output generating circuitry provides a signal indicating that the engine is not operating to the microcontroller when the circuitry is in an engine off condition and provides a signal indicating that the engine is operating to the microcontroller when the circuitry is in an engine on condition.

Claims

1. A timing circuit for providing an output signal to a monitoring circuit indicating whether an engine is operating, wherein said engine has a magneto, said circuit comprising:

a) switching means coupled to said magneto for periodically switching on and off in response to an operating condition of said engine; and

b) output generating circuitry coupled to said switching means for providing a signal indicating that said engine is not operating when said engine is in an off condition and providing a different signal when said engine is in an on condition.

2. The timing circuit of claim 1 wherein said switching means comprises a solid state switch.

3. The timing circuit of claim 1 wherein said switching means comprises a thyristor.

4. The timing circuit of claim 1 wherein said switching means comprises a triac.

5. The timing circuit of claim 2 wherein said solid state switch is activated by pulses generated by said magneto when said engine is operating to place said output generating circuitry in said on condition with said solid state switch in a conducting mode and wherein said circuitry comprises a capacitor that discharges to ground through said solid state switch thereby maintaining said output circuitry in said on condition.

6. The timing circuit of claim 2 wherein said solid state switch is deactivated when said magneto is not generating pulses to place said output generating circuitry in said off condition with the solid state switch not conducting current and wherein said circuitry comprises a transistor that switches to a conducting mode when said solid state switch is not conducting current to maintain said output circuitry in said off condition.

7. The timing circuit of claim 1 wherein said monitoring circuit comprises a microcontroller.

8. The timing circuit of claim 1 comprising a display for displaying a number of hours said engine has operated.

9. A timing circuit for providing an output signal to a microcontroller indicating whether an engine is operating, wherein said engine has a magneto that generates pulses when said engine is operating, said circuit comprising:

a) a thyristor coupled to said magneto for periodically switching on and off in response to an operating condition of said engine, wherein said thyristor conducts current when said magneto is generating pulses and does not conduct current when said magneto is not generating pulses;

b) output generating circuitry coupled to said thyristor comprising a capacitor and a switching transistor, said capacitor coupled between said thyristor and a base input of the switching transistor such that when said magneto is generating pulses said capacitor discharges through said thyristor and maintains said switching transistor in an nonconducting mode to provide a signal indicating that said engine is operating to said microcontroller and wherein said capacitor is coupled to said transistor through a zener diode such that when said magneto is not generating pulses and said thyristor is not conducting said capacitor charges beyond a zener voltage of said zener diode to switch said transistor to conducting mode to provide a signal indicating that said engine is not operating to said microcontroller.

10. The timing circuit of claim 9 wherein said thyristor comprises a triac.

11. The timing circuit of claim 9 further comprising a sensing means coupled to said microcontroller sensing a voltage at said capacitor and wherein said microcontroller records a time between drops in said voltage to determine the RPM of said engine.

12. The timing circuit of claim 9 comprising a display for displaying a number of hours said engine has been operated.

13. A method of providing an output to a microcontroller indicating whether an engine is operating, wherein said engine has a magneto, comprising the steps of:

a) coupling a switching means across a magneto coil that generates a spark plug voltage;

b) charging a capacitor to a voltage;

c) routing magneto generated pulses of either a positive or negative polarity to the switching means to activate the switching means and provide a discharge path to ground to said capacitor; and

d) said capacitor to determine an operating condition of said engine.

14. The method of claim 13 wherein said causing step is accomplished by routing said magneto generated pulses to said input switching means to disconnect said discharge path and cause said capacitor to charge.

15. A timing apparatus for monitoring and displaying the operation time of an engine of a riding lawn mower comprising:

a) a microcontroller comprising an engine monitoring circuit;

b) a timing circuit for providing an output signal to said monitoring circuit indicating whether an engine is operating, wherein said engine has a magneto, said circuit comprising;

i) switching means coupled to said magneto for periodically switching on and off in response to an operating condition of said engine; and

ii) output generating circuitry coupled to said switching means for providing a signal indicating that said engine is not operating to when said engine is in an off condition and providing a different signal when said engine is in an on condition; and

c) a display for displaying a number of hours said engine has operated.