Ignition module with low speed control

Patent metadata

Field	Value
Publication number	US-10907537-B2
Application number	US-201816495910-A
Country	US
Kind code	B2
Filing date	Mar 19, 2018
Priority date	Mar 21, 2017
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

In at least some implementations, an ignition system for a combustion engine includes analog circuit components arranged to control ignition events at an engine speed below a first threshold of engine speed and a microprocessor to control ignition events at engine speeds higher than the first threshold. Hence, ignition can be controlled at lower engine cranking speeds to facilitate starting the engine at lower engine rotational speeds.

First claim

What is claimed is:

1. An ignition system for a combustion engine, comprising:
analog circuit components arranged to control ignition events at an engine speed below a first threshold of engine speed and a microprocessor to control ignition events at engine speeds higher than the first threshold, wherein the analog circuit components control ignition events before the microprocessor has sufficient power for the microprocessor to control ignition events.

2. The system of claim 1 wherein the analog circuit components include a charge coil, a trigger coil, a main ignition switch, a peak detection circuit coupled to the main ignition switch and adapted to close the switch as a function of the magnitude of an induced voltage in the trigger coil.

3. The system of claim 2 wherein the analog circuit includes a peak and hold circuit that includes a power storage device that is separate from an ignition capacitor that is discharged when the main ignition switch is closed to cause an ignition event, and the power storage device is coupled to the charge coil to receive a portion of a voltage induced in the charge coil, and wherein the peak detection circuit includes a shorting switch coupled to the power storage device so that when a sufficient power level is provided from the power storage device to the shorting switch, the shorting switch is closed and energy in the peak detection circuit is short-circuited to ground to prevent the peak detection circuit from causing the main ignition switch to close.

4. The system of claim 1 which also includes at least one switch coupled to a power storage device of the analog circuit components and to ground, and wherein the microprocessor actuates the switch to short-circuit the power storage device when the microprocessor is operable to control ignition events.

5. The system of claim 1 wherein the analog circuit components are arranged to provide an ignition signal at an engine speed below 200 rpm.

6. The system of claim 1 which includes a magneto system which induces current in the trigger coil and the charge coil, and wherein power to operate the microprocessor comes from the trigger coil or the charge coil.

7. The system of claim 6 which includes a main charge storage element coupled to the charge coil, wherein the main charge storage element is charged when positive current is induced in the charge coil, and negative current induced in the charge coil is used to power the microprocessor.

8. The system of claim 1 wherein the charge coil is on a leg of a lamstack having at least two legs, and the trigger coil is on the same leg of the lamstack as the charge coil.

9. The system of claim 1 wherein the microprocessor is not powered by a battery or other DC power source.

10. The system of claim 1 wherein, when the microprocessor has power sufficient to operate, the microprocessor prevents the analog components from initiating an ignition event.

11. The system of claim 10 which also includes at least one switch coupled to ground and to a power storage device, wherein the power storage device is separate from an ignition capacitor that is discharged when the main ignition switch is closed to cause an ignition event, and wherein, to prevent the analog components from initiating an ignition event, the microprocessor actuates the switch to short-circuit the power storage device when the microprocessor is operable to control ignition events.

12. An ignition system for an engine having a flywheel, a magnetic element carried by the flywheel, and a piston, the system comprising:
a trigger coil and a charge coil arranged so that rotation of the flywheel passes the magnet near both the trigger coil and the charge coil to induce a current within the coils;
a main charge storage element coupled to the charge coil to store energy from the charge coil;
a main switch coupled to the charge storage element and to an ignition element to selectively couple the main charge storage element to the ignition element to provide power from the main charge storage element to the ignition element to cause an ignition event;
a peak detect charge storage element coupled to the trigger coil and to the main switch;
a peak detect switch coupled between the main switch and the peak detect charge storage element to selectively provide power from the peak detect charge storage element to the main switch to change the state of the main switch and permit power to flow from the main charge storage element to the ignition element to cause an ignition event; and
a controller coupled to the main switch to selectively change the state of the main switch, wherein the controller is powered by energy induced in a coil and provided to the controller when the engine is at a speed at which the energy above a threshold is induced in the coil that provides power to the controller so that the controller controls the state of the main switch and the timing of ignition events when the controller is provided with power above said threshold.

13. The system of claim 12 wherein the threshold is not a set value and is a power level at which the controller is sufficiently operational to be able to change the state of the switch.

14. The system of claim 12 wherein the coil that provides power to the controller is one of the trigger coil or the charge coil.

15. The system of claim 12 wherein the coil that provides power to the controller is a secondary coil that is not the charge coil or the trigger coil.

16. The system of claim 12 which also includes a lamstack having one or more legs, and wherein the trigger coil and the charge coil are wound on the same leg of the lamstack.

17. The system of claim 12 which also includes a shorting switch coupled between ground and the peak detect power storage element to selectively short to ground the peak detect power storage element, and wherein the switch is also coupled to the controller so that the controller can change the state of the switch to short to ground the peak detect power storage element to prevent the energy in the peak detect power storage element from being delivered to the main switch.

18. The system of claim 17 wherein two current pulses are induced in the trigger coil and wherein the analog circuit components include a peak and hold charge storage device coupled to the shorting switch to actuate the shorting switch and short the peak detect power storage device to ground so that the energy from one of the two pulses induced in the trigger coil is shorted to ground.

19. The system of claim 18 wherein a first one of the two current pulses occurs before a current pulse is induced in the charge coil and the a second one of the two current pulses occurs after the current is induced in the charge coil, and wherein the energy from the second one of the two current pulses is shorted to ground or otherwise dissipated.

Assignees

• Walbro Llc

Inventors

• Andersson Martin N
• Healy Cyrus M
• Linton Robby L

Classifications

• F02N2250/02

  Battery voltage drop at start, e.g. drops causing ECU reset · CPC title

• F02P5/1558

  with special measures for starting · CPC title

• F02P1/086

  for generating sparks by discharging a capacitor into a coil circuit · CPC title

• F02B63/02 Primary

  for hand-held tools · CPC title

• F02N3/02

  having pull-cords · CPC title