US2219070A - Speed control device for machines - Google Patents

Description

Oct. 22, 1940. Y

HERMITTE SPEED CONTROL DEVICE FOR MACHINES f8. Wer-279.5%

Patented Oct. 22, 1940 lPATIENT OFFICE SPEED CONTROL DEVICE FOR MACHINES Louis Hermitte, Paris, France, assignor to Socit Rateau, La Courneuve Seine, France, a corporate body of France Appiicatiuu August 9, 193s, serial No. 223,938 in France August 13, i937 4 claims. (c1. 264-7) The present invention relates to devices for automatically controlling the speed `of revolution of a prime mover. f

The object of the present invention is to provide a device for eifecting this controlling action/ in accordance with variations of the speed of another rotary machine.

According to the essential feature of the present invention, both the primary mover to be controlled and said other machine are each associated with a volumetric pump (that is to say a pump the rate of delivery of which is proportional to its speed of revolution) which they drive at speeds depending upon the speed of said prime mover and the speed of said other machine, respectively, according to predetermined relationships. The resistance of the discharge circuit of the pump associated with the prime mover1 is controlled in accordance with the discharge pressure of the other pump, and, in turn, the discharge pressure of said first mentioned pump controls the speed of revolution of said prime mover. f f i Y f Other features of the present invention will result from the following detailed description of a specific embodiment thereof. e

A preferred embodiment of the present invention will be hereinafter described, with reference to the accompanying drawing, given merely by way of example, and in which:

The only fgureis a diagrammatical view of a plant made according to an embodiment of the present invention.

As shown by the drawing I is a steam turbine which drives a utilization apparatus 2 of any kind whatsoever. It also drives, at .the same, or a proportional speed, a tachometric pump 3 of the volumetric type, that is to say, the rate of delivery of which is proportional to its speed of revolution. The pump 3 draws oil, or any other liquid, from a tank 4, through a pipe 5 and de` livers it through a pipe 6,` into the chamber 1 of a valve body 23, which communicates with a discharge chamberV 8, by way of a passage 9 between a proled valve I and its seat 24. The oil which has passed into the discharge chamber 8 then returns to the tank 4 .by way of a pipe Il.

Steam is supplied to the turbine I by a'pipel of the deliverylpipet of the volumetric pump 3 e through a pipe I5; Piston 4I carriesr a rod 43 provided, at itsv end', with a valve 44. This valve cooperates with aseat 45 which divides the valve body 46 into two chambers I3 and 41, the first of which communicates directly 'with the steam supply pipe I2, while the other communicates directly with the inlet of the turbine I.

This pressure regulator, which'is of conventional type, has its valve 44 designedin such man.. ner that it maintains ajuniform pressure in the pipe 6, for instance in the following manner,` corresponding to the example illustrated by the drawing: Y

When the pressure in the pipe 6 tends to drop,

piston 4I lis moved upwardly by its spring I4 and valve 44 opens the passage between chambers I4 and-31 to a larger area so that the feed of steam lto the turbine I' is increased, thus tending to accelerate the speed of said turbine in such manner as to compensate for the drop of pressure in pipe 6. Similarly, a rise of the pressure in said pipe 6 produces a movement of valve 44 in the'oppos'ite turbine.

n the other hand, the pressure inthe pipe 6 If the cross-sectional area of said passage 9 is f modified, the speed of the plant will belauto` matically varied until a knew value is attained in respect of which the velocity of the liquid-in the passage 9, and the delivery pressure of the pump once more attain their predetermined regulating value. 1

Thus, the speed of the turbine I' depends' upon the -area of the passage 9, andtherefore upon the position of the rod 32 (which carriesthe valve I0 cooperating with seat 24 for determining this passage). I will nowA explain how-the position of this rod 32 is controlled by the speed of the other machine 21. The machine 21 in accordance with the speed N2 ofwhich it is desiredv tocontrol the speed N I of the prime mover I, also drives a tachometric pump 28, the return circuit of which includes a pipe`29, the chamber 36 of a valve body 26, a

23. The other face of the piston 33 is subjected.H

to a counteracting spring 35.y

'I'he pressure in the pipe 29 depends on the delivery of the pump 28 (i. e. on the speed N2 of the machine 21) and on the cross-sectional-area of the passage 39 existing between the valve 3|) and its seat 20.

On the other hand, this pressure rshould bal-V ance the stress of the spring 35. Therefore,

starting, for instance, from a predetermined state of equilibrium, if the speed N2 increases, the

pressure in the pipe 29 will rise and compress the spring 35, thus lifting the valve 30 and increasing the cross-sectional a'rea of the passage 39 defined by that valve.

A new state of equilibrium is established for a slightly higher position of the valve 30. It will be evident, therefore, that, to each value of the speedN2, there will correspond a given position of rod 32, and oi' valve I0. Thus, according to the profile given to the valve IlI,a relation'can be established between' the speed N2 and the cross-sectional area of the passage 9 dened by said valve.

According to the foregoing, therefore, the speed NI of the prime mover I can, automatically, be made dependent on the speed N2 of the machine 21, in accordance with a predetermined relationship, by suitably designing` the profileV of the valve I0.

In order fully to explain the utilityof my device, I will give an example of an application thereof, to wit to the regulation of the combustion in a furnace.

ThisI application corresponds to the case of a furnace fed with liquid fuel by means of a volumetric pump driven by machine 21 `(and distinct from volumetric pump 28).

It will be supposed that the air necessary for the combustion of this fuel is fed by a blower or equivalent machine which is the utilization machine 2 driven by the turbine I.

The feed of the fuelto the furnace is substantially proportional'to the speed of revolution of the machine 21.

'Ihe feed of air supplied by the blower 2 depends, with a predetermined relationship, upon the speed of revolution of the turbine I, this 'relationship being determined by the Working characteristics of this blower and the resistance of the circuit into which it feeds air.

Variations of the operating conditions of the furnace are obtained by varying the speed of the machine 21, so as to feed a variable amount of fuel to the burners.

I'he result to be obtained is the automatic adaptation of the amount of air supplied by the blower 2 in such maner that, whatever be the feed of liquidvfuel, the feed of combustion air sent to the furnace corresponds to the best possible conditions `o1 combustion.

. This condition corresponds to a predetermined relationship between the feed of fuel and the feedof air, that is to say to a predetermined relationship of the speed of the turbine I and of the other machine 21.

The device an example of which has been above described permits of obtaining automatically this predetermined relationship, whatever it may be, and whether it is a simple law of proportionality or a more complicated law.

In the example above described, the machine 21 may be, for instance, an electric motor, a steam turbine, etc.

Also, it should bek well understood that the `prime mover I is not necessarily a steam turbine.

It may consist of any machine the speed of revolution of which is controlled by the position of the piston 4I `of the pressure responsive regulator.

Y Likewise, while, in the above example of application of my invention, I suppose that the furnace was fed with liquid fuel, it is clear that the invention applies as well to the case of a furnace with a movable grid for feeding coal. In this case, motor 21, instead of driving a fuel pump, would drive a continuous movement grid for the coal, and the device would ensure a predetermined relationship between the feed of the grid and the workingof the blower.

In a general manner, while I have, in the above description, disclosed what-I deem to be practical and efficient embodiments of the present invention, it should be well understood that I do not Wish to be limited thereto, as there might bechanges made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

l. In a plant including a machine and a motor, a device for regulating the speed of said motor in accordance with'the speed of Ysaid machine, which comprises, in combination,` a volumetric pump driven by said machine at al speed proportional to the speed thereof, a volumetric pump driven by said motor at a speed proportional to the speed thereof,l a discharge circuit for said second mentioned pump, means, operative by variations of the delivery pressure of said first mentioned pump, for varying the resistance of said discharge circuit to the flow of fluid therethrough, according to a predetermined law of correspondence between the delivery pressure of the v'i'lrst mentioned pump and the resistance of pump driven by said machine at a speed propori tional to the speed thereof, a volumetric pump driven `by said motor at a speed proportional to the speed thereof, a discharge circuit for said secondmentioned pump, a valve in said discharge circuit for more or less throttling said circuit according toA a predetermined law as a function of the displacement of said valve, means, operative by variations of said rst pump delivery pressure, for displacing said valve, and means, responsive to variations of the delivery pressure of said second pump, for controlling the speedv of said motor. 70

3. In a. plant including a machine and a motor, a device for regulating the speed KVof said motor in accordance with the speed of said machine, which comprises,` in combination, a volumetric pump driven by said machine at a speed propor- I* tional to the speed thereof, a discharge circuit for said pump, a volumetric pump driven by said motor at a speed proportional to the speed thereof, a discharge circuit for said second mentioned pump, a valve in each of said discharge circuits respectively for more or less throttllng it, a rod common to both of said valves for rigidly interconnecting them, means, operative by variations of the delivery pressure oi' said rst mentioned pump, for controlling said two valves, and means, responsive to variationsof the delivery pressure of said second mentioned pump, for controlling the speed of said motor,

4. In a plant including a machine and a motor, a device for regulating the speed of said motor in accordance with the speed of said machine, which comprises, in combination, a volumetric ton in said cylinder, a passage transmitting the 1o delivery preure of said first mentioned pump to one side of said piston in said cylinder means for rigidly coupling said piston with said rod, and means, responsive to variations of the delivery pressure ot said second mentioned pump, for conl5 trolling the speed of ma motor.

Louis Hmmm,

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