US2646814A - Speed governor for fluid operated rotary motors - Google Patents

Description

y 28, 9 P. M. MUELLER 2,646,814

I .SPEED GOVERNOR FOR FLUID OPERATED ROTARY MOTORS Original Filed Feb. 17. 1949 \L 3 T 30 l I I S 26 20 K I 38 l 22 i INVENTOR Pal/1M Mueller Patented July 28, 1953 SPEED GOVERNOR FOR FLUID OPERATED ROTARY MOTORS- Paul M. Mueller, West Hartford, Conn., assignor to Niles-Bement-Pond Company, West Hartford, Conn., a corporation of New Jersey Original application February 17, 1949, Serial No.

1950, Serial No. 162,987

4' Claims. (Cl. 137-58) This invention relates to a speed control for rotary motors, particularly to means for controlling the rotation of a high speed, elastic fluid turbine.- I

A primary object of the invention is to provide a simple speed controlling device particularly for the purpose of actuating a fluid admission valve to variable open positions to control the amount of motive fluid admitted to the motor or turbine intake.

Another object of importance of the invention is to provide fluid pressure means to move the fluid admission valve in one direction, the fluid applied to actuate the valve being supplied from the motive fluid for the turbine, the pressure of the fluid acting against the valve being varied by controlling the escape of fluid from a jet or orifice in the conduit connecting the motive fluid to the actuating means for the fluid admitting valve.

A feature of the invention that is important is that the escape of the motive fluid from the jet is varied by flexure, due to centrifugal force, of parts of a member closely adjacent the jet and rotated at high speed by the motor.

Another feature of the invention that is important is that the centrifugally flexed members comprise cantilevers or extensions, forming parts of a hollow cylindrical member, the free ends of the extensions being disposed adjacent the jet orifice and so disposed that with increased speed of rotation of the motor and greater flexureyfluid will escape from the jet more easily and reduce the pressure of fluid actingto force the fluid admission valve for the motor in a direction to reduce the amount of motive fluid admitted to the motor.

With the above and other objects in view, my invention may include the features of construction and operation set forth in the following specification and illustrated in the accompanying drawing.

In the accompanying drawing annexed hereto and forming a part of this specification, I have shown my invention embodied in the controlling of a piston operated throttle valve for controlling the admission of motive fluid to a turbine to maintain constant, but adjustable, rates of r tation of the turbine; it will be understood, however, that the invention can be otherwise embodied and that the drawing is not'to be construed as'defining or limiting the scope of the invention, the claims appended'to this specification being relied upon for that purpose. I

In the drawings Figure 1 is a schematic view of a turbine show- Divided and this application May 19,

2 ing a cross-sectional view of a fluid admitting valve and. its control mechanism;

Fig. 2 is a side elevation of a member of the control device rotated in timed relation to the turbine; and

Fig. 3 is a front elevation of the member shown in Fig. 2.

In the above mentioned drawing, I have shown but one embodiment of the invention which is now deemed preferable, but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

This application is a division of my copending application Serial No. 77,031, filed February 17, 1949.

Briefly, and in its preferred'aspect, the invention may include the following principal parts: First, a fluid admitting valve movable axially within a suitable valve casing to vary the supply of motive fluid admitted to a motor or turbine; second, a piston preferably formed on the valve and movable within a cylinder with movements of said valve; third, a spring normally forcing said valve and piston in one direction; fourth, conduits for supplying fluid to said valve and for supplying fluid from said valve to said turbine intake; fifth, a conduit in the control system for supplying pressure 'to said cylinder to actuate the piston and valve against the pressure of the spring; sixth, means to restrict the flow of fluid in the control system; seventh, a jet formed in said fluid control system; and eighth, a member rotating in timed relation to the turbine and having slightly flexible portions movable toward and away from the jet orifice to vary the pressure of fluid escaping from the orifice and control the rotative speed of the turbine.

Referring more in detail to the figures of the drawing, there is shown a turbine or other form of rotary motor H] operated by fluid under pressure. The motor or turbine I0 is supplied with motive fluid from any suitable source [2, the fluid passing through a throttle or other form of valve l4 and from the valve through conduit i5 directly to the turbine intake I6. The valve I4 is movable axially within a casing iii to vary the opening of its supply port 20 and control the amount of fluid admitted to conduit l5 and to the turbine Hi. The valve I4 is normally pressed by a helical spring 22, wrapped about a portion of the valve extension 24, in a direction to close the port 20 admitting motive fluid to the turbine so that a pressure acting to move the valve Ii in a direction to close the admission port 20 is at all times existent.

To move the valve M in a direction to open the admission port to increase the amount of motive fluid supplied to the turbine, a piston 26 is mounted on, or forms part of the valve M. Thi piston operates within a short cylinder 28 to which motive fluid may be admitted at one end to force the piston 26 and valve I 4 in a direction to open port 28 against the pressure of the spring 22.

Rotated at high speed by the turbine, by any desired means not shown, is the cylindrical member 36 which, as shown in Figs. '2 and 3, is slotted to form a plurality of closely and equally spaced projections 33. Each of the sections 38 between the slots 39 cut into the cylindrical surface of the member is elongated sufficiently to be flexed slightly by centrifugal action at high rotative speeds. Different speeds will flex the extensions 38 varying small amounts and will, therefore, vary the space between the jet orifice 32 and the surfaces of the projections 38. Varying the area of the escape from the jet 32 will inversely vary the pressure exerted against the piston 26.

To admit fluid at variable pressures to the cylinder 23 and force the piston 26 to actuate the valve i l to variable, intermediate fluid supplying positions, the following means are provided.

The total control can be "divided into three systems: (1) the control circuit represented by the conduit 30, the side branch 3 l, a needle valve 34 and a jet or nozzle 32, (2) the speed sensitive element 35 with its cantilevers 3B and (3) a pressure sensitive system comprising the piston 2%, spring 22 and valve it.

The control circuit carries a flow of fluid through conduit :from the supply pressure at 12 and discharges through the jet or nozzle 32 into atmosphere or other low ambient pressure. The "jet or nozzle 32 extends at right angles to the axis 'of rotation of the member 25 and is partially blocked by the cover "of the cantilever 38 and forms a restriction to the flow. A second rectriction is interposed at the manually adjustable valve The pressure in the conduit 3t] intermediate the two restrictions -32 and 34 can be made to assume any value between the supply pressure at 2 and the ambient pressure at 32 depending solely upon the ratio of the efie'ctive areas or" the two restrictions 32 and B ll. This intermediate pressure, hereafter called the signal pressure, is transmitted through the branch 31 and acts upon the piston 25.

It is evident that when this signal pressure hecomes great enough, the piston 26 will overcome the reaction of the spring 22', open the valve l and position its degree of opening in accordance with the rate of the spring 22. By a proper choice of piston area and spring rate, it is possible to move the valve is from closed to lull open with a small change of signal pressure. If the spring 22 is given a suitable preloading, the level of the signal pressure can be raised to any desired value. For instance, a spring load can be chosen such that valve Hi will crack open when the signal pressure is 60 p. s. i., and a rate selected such that the opening of valve i l will be complete when the signal pressure is 63 p. s. i.

It is to be noted then, that the pressure sensitive system 25-22'-M, can be designed for a relatively constant signal pressure, small variations of which can progressively operate it through its entire function.

I The control circuit 3@'3l3 l32' can provide this signal pressure "by'ipro'p'er proportion of the restrictions 32"and 34. "Tlfisratio is fixed once the proportions of the system 2 6' 22i4 are de- 4 fined, but the actual areas of the restrictions 323 l can be of any reasonable value provided only that they have this ratio to one another.

If the restriction at 32 is given a definite area by lifting the cantilever 33 a small distance away from the jet 32, the valve 34 must also be given a definite area in order to produce the designed signal pressure in branch 3i and on the piston 2%. Conversely, if the area of valve 34 is given any arbitrary value, the cantilever 38 must be sprung to the correct distance away from the jet 3? in order for the signal pressure to reach the design level and actuate the valve M.

It will be now evident that when the restric tion 341's held at a constant value, movement of the cantilever asaway from the jet 32 will progressively reduce the signal pressure from a value higher than the design level, to the design level, and then below the design level.

In the operation of the turbine, the centrifugal force of the rotating speed sensitive element 33 lifts the cantilevers 33 to the point Where the signal pressure lowers to the design level, the valve it throttles and maintains essentially-constant speed.

If a load is now imposed upon the turbine, its speed will drop slightly, lower thecantilevers 38, increase the resistance of the restriction at 32-, build up the signal pressure on the piston 26 and open the valve M to the degree necessary to supply the required arnount of motive fluid to the turbine to handle the extra power demand.

Conversely, if load is removed fromthe turbine, its speed will increase slightly, raise the canti levers 38, decrease the restriction at 32, reduce the signal pressure, andthe spring 22 will throttle the valve Hi.

What I claim is:

1. Means to vary the nozzle opening of a jet comprising -;in combination, a nozzle having an orifice, a rotatable member mounted for rotation onan-axisnormal to the axis of said nozzle and having a cylindrical portion slot-ted to form flexible extensions, said extensions being adjacent and in flow restricting relationship with the orifice QfBa-id nozzle, whereby when said member is rotated at variable speeds said extensions are flexed toward and from said orifice to vary the escape of fluid from said jet through said nozzle.

2. Means to vary the nozzle opening of a jet comprising ,in combination, a nozzle having an orifice, rotatable member mounted for rotation on an axis normal to the axis of-said nozzle and having a c lindrical portion slotted parall'elly to the axis or rotation to "form spaced flexible extensions, saidextensions bei'ng adjacent and inflow restricting relationship with the orifice of said nozzle, whereby when said member is rotated at variable speeds, said extensions are radially flexed to vary the escape of fluid from said jet through said-nozzle.

3. Means to vary the-nozzleopening of a jet, comprising in combination, a nozzle having an orifice,-'a'n1 enrber rotatable on its central axis normalto the nozzle axis and having a portion slotted longitudinally at spaced angularly disosed positions to form an annular series of radialiy ilexible'extensions, said extensions being adj agent andi'n flow restricting relationship with said nozzle orifice, whereby when "rotated said extensions will be flexed radially from said nozzle orifice to vary thee's'cap'e of fluid from said jet through said nozzle.

4. Means tova'r the nozzleppening or a jet,

comprising in combination, a cylindrical member mounted for rotation on a fixed axis, said member having angularly spaced longitudinally extending slots tovform an annular series of projections, the free ends thereof being radially flexed at high rotative speeds of said member, a supply of fluid under pressure, a nozzle through which said fluid passes extending at right angles to the axis of rotation of said member and having an orifice within said member adjacent and in fiow restricting relationship with the free ends of said projections, whereby vari- 6 able rotative speeds of said member will vary the gap between said orifice and the free end surfaces of said projections and vary the escape of fluid from said nozzle.

PAUL M. MUELLER.

References Cited in the file of this patent FOREIGN PATENTS Country Date

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