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CONTROL SYSTEM AND METHOD FOR PREVENTING ENGINE OVERSPEED

IP.com Disclosure Number: IPCOM000246983D
Publication Date: 2016-Jul-20
Document File: 3 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a control system and method that effectively controls engine overspeed condition by momentary shut-off of fuel valve. The system uses a fast acting main fuel valve that is responsive to control system inputs acting on engine speed sensing. The system measures the speed of the engine and controls the fuel valve based on an overspeed threshold condition. If the speed exceeds the threshold condition, the main fuel valve of the engine is closed to retard the speed. After the momentary shut-off of the fuel valve, the system again measures the speed and if the speed decreases, the main fuel valve is opened. The method reduces unburnt hydrocarbons in the exhaust and prevents occurrence of exhaust explosion or backfire during an instant unloading of the engine. The system and method could be implemented in any internal combustion engine such as automotive or motorsport engines.

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CONTROL SYSTEM AND METHOD FOR PREVENTING ENGINE OVERSPEED

BACKGROUND

The invention relates to control system for IC engines and method for better control of the engine operation during overspeed conditions. During engine overspeed, power generation engines are subjected to a circuit breaker trip condition which instantly takes away load on the engine. In the same circumstances, a spark ignited engine uses a throttle to control engine speed and the engine quickly accelerates until the throttle could respond. The response from the throttle is not fast enough to prevent shutdown during engine overspeed which typically occurs at 10% above rated speed. In addition, when the throttle rapidly closes, it causes a disruption to the mixing and flow of air and fuel, which results in unburned fuel in the exhaust system. The ignition of the unburned fuel causes combustion in the exhaust system resulting in a loud exhaust explosion or backfire. Existing systems and methods for controlling the engine during overspeed involve faster governor response, heavier flywheels or generator rotors, actively retarding ignition timing when engine speed exceeds the rated speed. These methods have several other disadvantages including high cost or complexity. Thus, there is a need for a control system which could prevent engine overspeed without relying only on the throttle response and reduce exhaust explosion or backfire during an instant unloading of the engine.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses a control system and method for preventing engine overspeed, wherein:

FIG. 1 shows a schematic of control logic for momentary shut-off of fuel valve to prevent engine overspeed condition.

DETAILED DESCRIPTION

The invention proposes a control system and method that effectively controls engine overspeed condition by momentary shut-off of fuel valve. The system uses a fast acting main fuel valve that is responsive to control system inputs acting on engine speed sensing. The system is configured to close the main fuel valve when the engine speed exceeds a first predetermined level that is lower than the overspeed setting. Then, the system is configured to open the main fuel valve when the engine speed falls below a second predetermined level that is below the first predetermined level and at or above the rated speed.

The system and method for controlling the engine operation during overspeed condition using control logic, as indicated in FIG. 1....