Importance

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Abstract

A jet pump (14) is inserted between the low-pressure pump and a high-pressure fuel pump (16). A fuel metering unit (20) includes a metering valve (22) which delivers a regulated fuel flow to a feed line (30), and a bypass valve (24) which diverts to a primary intake (14a) of the jet pump the excess fuel flow supplied by the high-pressure pump. An overspeed protection unit (50) includes a control element (54) of the bypass valve (24) which causes said to fully open in the event of an overspeed of the engine. A shutoff and pressurization checkvalve (42) is mounted on the feed line and controlled by a servo-valve (44) having a high-pressure port (44a) brought to the high fuel pressure, a low-pressure port brought to the pressure of the primary intake (14a) of the jet pump and an output setting the pressure in a control chamber (42a) of the shutoff valve (42) to a value between those prevailing at the high pressure and low pressure ports. In the event of overspeed, the restriction imposed by the jet pump causes a pressure rise at the primary intake of the jet pump, hence a pressure rise in the control chamber of the shutoff valve (42), favoring the closing thereof.

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First Claim