Shutdown circuit for an ignition system of a lawn care device in case of defective processor

Patent metadata

Field	Value
Publication number	US-2016356255-A1
Application number	US-201415102372-A
Country	US
Kind code	A1
Filing date	Dec 12, 2014
Priority date	Dec 12, 2013
Publication date	Dec 8, 2016
Grant date	—

Abstract

A lawn care device may include an engine to selectively power the lawn care device, a frame supporting the engine of the lawn care device, an ignition system for selectively powering the lawn care device based at least in part on operation of an ignition interface controlled by a processor ( 310 ), an optical isolator ( 320 ) which detect the operational presence of the processor ( 310 ) and a shutdown circuit ( 300 ) which is able to ground out the ignition coil ( 360 ) as a function of the conductive state of the optical isolator ( 320 ); the shutdown circuit being powered by an ignition coil ( 360 ) of the ignition system to generate a failsafe condition in response to failure or loss of the processor ( 310 ).

First claim

That which is claimed:

1 . A lawn care device comprising:
an engine to selectively power the lawn care device; a frame supporting the engine of the lawn care device; an ignition system for selectively powering the engine based at least in part on operation of an ignition interface controlled by a processor; and a shutdown circuit controlled by the processor, but powered by an ignition coil of the ignition system to generate a failsafe condition in response to failure or loss of the processor.

2 . The lawn care device of claim 1 , wherein the shutdown circuit comprises an optical isolator configured to interface with a gate bias circuit to trigger a shutdown switching component to short the ignition coil in response to the failure or loss of the processor.

3 . The lawn care device of claim 2 , wherein the optical isolator acts as a gate bypass relay to prevent the gate bias circuit from triggering the shutdown switching component in response to receipt of a signal indicative of operational presence of the processor.

4 . The lawn care device of claim 3 , wherein the optical isolator stops conducting to alter the gate bias circuit to trigger the shutdown switching component to short the ignition coil in response to loss of the signal indicative of operational presence of the processor.

5 . The lawn care device of claim 2 , wherein the shutdown circuit further comprises a rectifier circuit disposed between the ignition coil and the gate bias circuit to enable the gate bias circuit to operate to trigger the shutdown switching component regardless of a polarity of an input to the rectifier circuit from the ignition coil.

6 . The lawn care device of claim 2 , wherein the optical isolator comprises a transistor output optocoupler.

7 . The lawn care device of claim 2 , wherein the shutdown switching component comprises a bipolar junction transistor (BJT), or a field effect transistor (FET).

8 . The lawn care device of claim 1 , further comprising an RPM monitoring circuit powered by the ignition coil.

9 . The lawn care device of claim 9 , wherein the RPM monitoring circuit is configured to measure RPM regardless of a polarity of a signal provided from the ignition coil.

10 . An ignition system for a lawn care device, the ignition system selectively powering the lawn care device, the ignition system comprising:
an ignition coil for ignition of an engine of the lawn care device; a processor configured to control the ignition system; and a shutdown circuit controlled by the processor, but powered by the ignition coil to generate a failsafe condition in response to failure or loss of the processor.

11 . The ignition system of claim 10 , wherein the shutdown circuit comprises an optical isolator configured to interface with a gate bias circuit to trigger a shutdown switching component to short the ignition coil in response to the failure or loss of the processor.

12 . The ignition system of claim 11 , wherein the optical isolator acts as a gate bypass relay to prevent the gate bias circuit from triggering the shutdown switching component in response to receipt of a signal indicative of operational presence of the processor.

13 . The ignition system of claim 12 , wherein the optical isolator stops conducting to alter the gate bias circuit to trigger the shutdown switching component to short the ignition coil in response to loss of the signal indicative of operational presence of the processor.

14 . The ignition system of claim 11 , wherein the shutdown circuit further comprises a rectifier circuit disposed between the ignition coil and the gate bias circuit to enable the gate bias circuit to operate to trigger the shutdown switching component regardless of a polarity of an input to the rectifier circuit from the ignition coil.

15 . The ignition system of claim 11 , wherein the optical isolator comprises a transistor output optocoupler.

16 . The ignition system of claim 11 , wherein the shutdown switching component comprises a bipolar junction transistor (BJT), or a field effect transistor (FET).

17 . The ignition system of claim 10 , further comprising an RPM monitoring circuit powered by the ignition coil.

18 . The ignition system of claim 17 , wherein the RPM monitoring circuit is configured to measure RPM regardless of a polarity of a signal provided from the ignition coil.

19 . A shutdown circuit for an ignition system of a lawn care device, the ignition system selectively powering the lawn care device, the ignition system comprising:
an ignition coil for ignition of an engine of the lawn care device; and a processor configured to control the ignition system; and an optical isolator configured to interface with a gate bias circuit to trigger a shutdown switching component to short the ignition coil in response to the failure or loss of the processor.

20 . The shutdown circuit of claim 19 , further comprising a rectifier circuit disposed between the ignition coil and the gate bias circuit to enable the gate bias circuit to operate to trigger the shutdown switching component regardless of a polarity of an input to the rectifier circuit from the ignition coil.

Assignees

• Husqvarna Ab

Inventors

• Albinger Matt
• Beuger Paul

Classifications

• A01D34/64

  mounted on a vehicle, e.g. a tractor, or drawn by an animal or a vehicle (A01D34/695 takes precedence) · CPC title

• F02P3/04

  Layout of circuits · CPC title

• F02P5/15 Primary

  Digital data processing · CPC title

• F02B77/08

  Safety, indicating, or supervising devices (thermal insulation F02B77/11; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00) · CPC title

• F02D41/042

  for stopping the engine · CPC title