US2515074A - Fuel feed governor for gas turbines - Google Patents

Description

July 11, 1950 w. s. BOBIER, JR 2,515,074

FUEL FEED GOVERNOR FOR GAS TURBINES Filed NOV. 6, 1948 VIZ/S. Babies)" Jr:

INVENTOR.

ATTORNEY Patented July 11, 1950 FUEL FEED GOVERNOR FOR GAS TURBINE Wilfred S. Bobier, Jr., Grosse Pointe Woods, Mich., assignor to George M. Holley and Earl Holley Application November 6, 1948, Serial No. 58,647

2 Claims.

The object of this invention is to throttle the fuel in response to the centrifugal force at a preselected speed and to maintain this speed under all circumstances.

It is usual to provide means for preventing overshoot as well as to prevent droop. However, when a governor is actually controlling the speed the means for preventing overshoot interferes with the governing.

The object of this improvement is to automatically eliminate the overshoot correcting the restriction 50 retards the opening motion of the valve 20 to prevent overshoot. This retardation is not needed once the governor begins to function, that is, once the valve 12 begins to open. Due to the closure of throttle valve 20 valve 12 establishes a constant pressure drop around the main fuel restriction 2| so that every means the moment the governor actually begins to govern.

The figure shows diagrammatically the preferred form of my invention. I

In the figure, I is the fuel entrance leading to the governor controlled valve 20. I2 is the constant pressure valve which is provided with an annular groove l4. This valve is provided with a compression spring l6. I8 is the escape passage returning the fuel to the supply pump, not shown. The pressure of the fuel downstream of the throttle valve 20 assists the spring it in closing the valve I 2. This pressure is transmitted from the main discharge passage 22 through the small passage 24. The result is that there is constant pressure drop at restriction 2|. A centrifugal governor 26 controls the throttle valve 20. The preselected speed is selected by the manually adjusted cam 28, cap 30 and compression spring 32 A venturi 34 establishes a low pressure in chamber 36 through therestriction 38. Droop restriction 40 raises the pressure in chamber 36 by admitting fuel pressure from inlet passage l0, through filter 44 to passage 46 which passage also communicates with chamber 48 in which the governor 26 revolves. The overshoot restriction 50 connects the passage 46 with chamber 52, to the right of a diaphragm 54. A spring 56, to the left of diaphragm 54, engages with valve 20 through rod 60 and transmits the pressure difforence on diaphragm 54 to the valve 20.

Check valve 62, which is spring loaded, acts to still further limit the effective action of the overshoot restriction 50. I have made use of the annular depression M in the skirt of the valve l2 to short circuit entirely the overshoot restriction 50 once the valve l2 opens. Intermediate pressure passage connected to chamber 52 and high pressure passage 12 are put into communication with each other by valve I2 acting as a slide valve. Once valve I2 rises overshoot restriction 50 ceases to function which is the object of this invention.

Normally when rotating cam 28 anti-clockwise position of valve 20 corresponds to a specific fuel flow.

This application is a continuation in part of patent application Serial No. 783,071 filed October 30, 1947.

What I claim is:

1. A fuel control system for a gas turbine, a source of fuel under pressure, a fuel supply passage and a first throttle valve leading to a prime mover, a speed responsive means applying force to said throttle valve that increases with speed, an orifice in said passage controlled by said throttle, manually variable yieldable means opposing said speed responsive force, a second constant pressure valve connected upstream of said first throttle valve and controlled by the pressure downstream of said first throttle valve, overshoot control means to check the opening of said throttle when the yieldable load is reduced comprising a moving wall engaging with said throttle, a first chamber associated therewith and in restricted communication with the entering fuel under pressure, a second chamber associated with the other side of said moving wall,

fu'el flow responsive means for maintaining the pressure in said second chamber at a lower pressure than the pressure of the entering fuel, a connection from the moving wall to said first throttle valve so that the pressure diiference acting on said moving wall assists the yieldable means in opposing the speed responsive force and so tends to open the valve means associated with the second constant pressure .valve to bypass the restriction to said first chamber whenever the second constant pressure valve opens to reduce the fuel flow to said gas turbine.

2. A device as set forth in claim 1 in which the fuel flow responsive means comprises'a fuel venturi located upstream of said first throttle valve.

WILFRED S. ,BOBIER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

' FOREIGN PATENTS Number

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