Engine control unit enablement system
Patent No. US6914342 (titled "Engine control unit enablement system") on Feb 6, 2004. The application was issued on Jul 5, 2005.
What is this patent about?
’342 is related to the field of internal combustion engine control systems, specifically focusing on power management for electronics in manually started or battery-less engines. In applications like outboard motors or snowmobiles, the engine control unit and fuel injectors often require high-voltage power that must be generated rapidly during a pull-start sequence to ensure the engine fires on the first attempt.
The underlying idea behind ’342 is to treat a high-capacity filter capacitor as a temporary reservoir that is physically isolated from the electrical load when the engine stops. By using a sensor to detect the exact moment rotation ceases, the system triggers a switch to break the circuit, trapping the residual charge within the capacitor so it does not bleed out through the engine electronics during periods of inactivity.
The claims of ’342 focus on a power management architecture that utilizes an engine position sensor to drive an enablement circuit. This circuit acts as a gatekeeper between a non-battery energy storage device and the engine control unit, automatically opening a conductive path upon engine shut-down and closing it immediately when the sensor detects the first signs of crankshaft or flywheel rotation.
In practice, the system employs a crank position sensor to monitor the movement of magnetic teeth on the flywheel. When the engine is running, the alternator charges a large capacitor to a high rail voltage, such as 55 volts, to power responsive fuel injectors. As soon as the sensor indicates the engine has dropped below a functional idle speed or stopped entirely, the controller toggles a power switch—often a Darlington transistor configuration—to disconnect the capacitor from the rest of the system.
This approach differs from prior designs where capacitors were permanently hard-wired to the voltage rail, causing them to drain in milliseconds once the alternator stopped spinning. By maintaining a trapped charge, the invention ensures that the very first movement of a pull-rope provides instant electrical potential to the electronics, bypassing the usual delay required to recharge the system from a dead state and significantly improving cold-start reliability.
How does this patent fit in bigger picture?
Technical Landscape
In the mid-2000s when ’342 was filed, manual-start internal combustion engines for recreational and marine applications were increasingly transitioning from purely mechanical systems to electronically controlled architectures to meet tightening efficiency and emission standards. This was a time when engine control units and high-voltage fuel injection systems were typically powered by electrical energy generated during the starting sequence itself, often relying on the rotation of a flywheel to charge capacitors via an alternator. In these systems, hardware constraints made rapid startup non-trivial because energy storage components commonly remained connected to the system electronics after engine shutdown, causing stored electrical energy to dissipate through the load. Consequently, when systems relied on manual rope-start mechanisms rather than integrated battery systems, the initial pull was often insufficient to simultaneously recharge the depleted capacitors and provide the high current necessary to wake the control electronics and fire the injectors.
Prosecution Position
The disclosed invention represents a meaningful technical advancement by introducing an architectural shift in the power management of engine electronics that preserves electrical energy across shutdown cycles. By integrating an enablement circuit that selectively opens and closes the conductive path between a non-battery energy source and the engine control unit based on real-time rotational feedback, the system overcomes the technical constraint of parasitic energy loss during periods of non-operation. The structural solution utilizes a crank position sensor to detect the cessation of engine rotation and trigger a power switch that electrically isolates the storage device from the engine electronics. This achieves the technical effect of maintaining a residual charge in the energy source, enabling nearly instantaneous powering of the control unit upon the first detection of rotation during a subsequent start-up, thereby reducing the manual force and number of attempts required to initiate combustion.
Claims
The patent contains a total of 18 claims, with claims 1, 5, 7, and 16 serving as the independent claims. These independent claims focus on an engine power management system and an electronically controlled engine, specifically an outboard motor, that utilizes sensors and controllers to manage the transfer of electrical energy from a source to electronic components based on engine operating status or shutdown. The dependent claims further define the system by specifying components such as crank position sensors, flywheels, filter capacitors, and engine control units, while also detailing the conversion of power and the specific conditions under which electrical energy is stored or disconnected.
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US6914342
- Application Number
- US10708091A
- Filing Date
- Feb 6, 2004
- Publication Date
- Jul 5, 2005
- External Links
- Slate, USPTO , Google Patents