US465014A - Method of and apparatus for supplying motive fluid to engines - Google Patents

Description

, B. BRAZELLE. METHOD OF AND APPARATUS FOR SUPPLYING MOTIVE FLUIDS T0 ENGINES;

Patented Dec 15, 1891.

(No Model.)

UNITED STATES PATENT OFFICE.

BENJAMIN BRAZEIJLE, OF ST. LOUIS, MISSOURI.

METHOD OF AND APPARATUS FOR SUPPLYING MOTIVE FLUID TO ENGINES.

SPECIFICATION forming part of Letters Patent No. 465,014, dated December 15, 1891.

Application filed April 21, 1891- Serial No. 389,767. (No model.)

To all whom it may concern:

Be it known that I, BENJAMIN BRAZELLE, of St. Louis, in the State of Missouri, have i11- vented a certain new and useful Improvement in Methods of and Apparatus for Supplying Motive Fluid to Engines, of which improve ment the following is a specification.

The object of my invention is to attain as high an economy as practicable in the operation of fluid-pressure engines by utilizing the expansive force of motive fluid from any determined initial pressure, whether comparatively high or low, to a fixed low or zero terminal, irrespective of variations of load or initial pressure-in other words, to enable the maximum economy to be attained whether the duty of the engine requires the development of its maximum or its minimum power.

Under present practice an engine which may operate economically when exerting, say, one hundred horse-power will not be found economical when operated at ten horse-power,

and hence no material range of variation of load is usefully admissible. Further, in the operation of an engine in which a desired terminal pressure is attained when steam is worked at maximum pressure and with a determined degree of expansion the terminal will be found to fall much below atmospheric pressure with the attendant loss due to condensation and re-evaporation when cutting off shorter for lighter loads or higher pressure.

Again, in automatic cut-off engines it is not practicable to effect perfect regulation within any material range of variation of load or pressure.

My invention is designed to obviate the objections'which, as above indicated, obtain in present practice; and, generally stated, it consists in a method of and apparatus for coincidently changing the degree of expansion or point of cut-off and the degree of initial pressure, in accordance with variations of pressure or load, or both, in the operation of an engine, expansion being varied in reverse direction to the variation in ordinary prac- Iicethat is to say, the point of cut-off being made earlier in accordance with increase of load or pressure and later in accordance with decrease, while the same fixed low terminal is reached in all cases. The loadline is so regulated as to be brought to the fixed terminal by varying the point of cut-off, as above stated, and the pressure-line is correspondingly and coincidently regulated by varying the initial pressure from which expansion is effected.

In the practice of my invention as applied in the operation of engines of the present standard construction a cut-off mechanism and a fluid-supply valve are coincidently acted upon bya regulating mechanism of any suitable construction, so as to simultaneously Vary the degree of initial pressure and the point of cut-0E, raising the former and shortening the latter in accordance with required increase of power, and, conversely, lowering the former and lengthening the latter in accordance with required decrease of power. Such variation may be effected by the employment of two governors or regulators, one of which acts upon the cut-off mechanism and the other upon the throttle or supply valve, or by a single regulating mechanism of such construction as to be adapted to act simultaneously upon the cut-off mechanism and the throttle-valve.

In the accompanying drawings, Figure 1 is a view, partly in elevation and partly in section, of so much of an engine adapted to the practice of my invention as is necessary to explain the same; Fig. 2, an indicator diagram such as would be produced under my invention, and Fig. 3 an indicator diagram such as is produced in the operation of an ordinary automatic cut-off engine.

The drawings illustrate the application of my invention on an automatic cut-01f slidevalve engine of the ordinary type, the distribution-valve being actuated and controlled by a loose eccentric and cut-off governor on the main shaft, and the steam-supply being controlled by an ordinary centrifugal throttlinggovernor connected to the steam-pipe and valvechest. Motive fluid is admitted through the inlet 5 and governor-valve t to the valvechest 1 and thence through the ports 16 16 to the cylinder 1, acting upon the piston 2,which, through the usual connections, rotates the crankshaft 10. Motive-fluid supply is regulated by a throttling-governor 3, and variation of the degree of expansion or point of cut-off is effected by a cut-off governor or reg ulator X, mounted on and rotating with the crankshaft. The governor X is composed of a supporting disk or case 7, fixed upon the shaft 10, a pair of centrifugally acting weights 12, connected to arms 13, which are pivoted to the case and coupled by links 14 to an arm 11, carrying a movable eccentric 8, and a centripetally-acting spring 15, coupled to the case and to the eccentric carrier-arm 11. A slot 9 is formed in the eccentric 8, through which the shaft 10 passes, and the rod of the eccentric 8 is connected with the slide distribution valve 6 in the ordinary manner.

The engine may be assumed to be speeded to one hundred revolutions per minute and to develop fifty horse-power with one hundred pounds initial pressure cut off at one-twentieth of the stroke, the steam expanding down to five pounds terminal pressure. Should the load be reduced or pressure increased, the speed of the engine would be slightly increased, causing the throttling-governor 3 to partially close the valve 4, thereby reducing the supply-pressure. At the same time the Weights 12 of the shaft-governorX move outwardly, and, through their arms 13 and the links 14, move the eccentric 8 transversely to the shaft, increasing the throw of the eccentric and the travel of the distribution-valve 6, thereby effecting a greater degree of opening of the ports 16 16 and cutting ofi later in the stroke. When the load is increased or the pressure reduced and the speed of the engine thereby reduced, the throttling-governor 3 will open the valve 4, thereby increasing the initial pressure in the cylinder, and at the same'time the weights 12 of the cut-off governor X will move inwardly, when the spring 15 will move the eccentric Sin the opposite direction, reducing its throw and the travel of the valve, thereby eifecting a lesser degree of opening of the cylinder-ports and cutting off shorter. The coincident action of the supply and cut-0E governors, as above described, is exerted in accordance with all changes of load and steam-pressure.

The diagram Fig. 2 indicates the diiferent points of cut-off corresponding .with variations of initial pressure. If the initial pressure falls to seventy-five, fifty, twenty-five, or ten pounds, the point at which steam is cut off will be indicated by A, B, O, or D, respectively, the terminal pressure being in each case five pounds or the determined terminal or zero of the normal initial pressure of one hundred pounds. Upon a proportionate decrease of load the initial pressure is reduced bythe throttling-governor 3 to seventyfive, fifty, twenty-five, or ten pounds, and the point of cut-off changed by the cut-off governor X to that indicated by A, B, C, or D, respectively, the terminal pressure being in each case five pounds. Under other variations of load or initial pressure, occuring either independently or coincidently, the degrees of initial pressure and points of cut-oft would be indicated by points between the lines A, B, C, and D, but on the same expansion-line F and resulting in the same fixed terminal.

From the diagram Fig. 3, which indicates the results of the ordinary method of using steam expansively in automatic cut-off engines, it will be seen that when the initial pressure is one hundred pounds and the steam is cut off at one-twentieth of the stroke the terminal pressure is five pounds; but when, with an increase of load, the steam is cut off at one-quarter of the stroke the terminal pressure is thirty pounds, and when, with a maximum load, the steam is cut off at onehalf the stroke the terminal pressure is fiftyeight pounds. WVith a minimum load the steam is cut off at'so early a period in the stroke as to cause a vacuum to be formed in the cylinder, as indicated by the loop H, the disadvantage of which in resultant condensation and re-evaporation is well understood. The expansion curve with minimum load is shown by D.

In my improved method, with maximum l0ad,steam at an initial pressure of one hundred pounds is cut off at one-twentieth of the stroke, giving a terminal pressure of five pounds, and with a minimum load the initial pressure is reducedto ten pounds and steam is cut off at one-half stroke, givinga terminal pressure of five pounds.

I claim as my invention and desire to secure by Letters Patent 1. The improvement in the method of supplying motive fluid to engines, which consists in maintaining a uniform determined terminal pressure by coincidently varying in reverse direction the degree of initial pressure and the degree of expansion or point of cutoff in accordance with and proportionately to variations in pressure or load, or both, substantially as set forth.

2. In an engine actuated by expansive-fluid pressure, the combination, with a cylinder and piston, of a fluid-supply valve, a cut-off mechanism, and regulating mechanism conneeted with and acting coincidently upon said fluid-supply valve and cut-off mechanism, so as to simultaneously varyin reverse direction the initial pressure and the point of cut-off in the cylinder, substantially as set forth.

3. In an engine actuated by expansive-fluid pressure, the combination, with a cylinder and piston, of a supply-valve controlling the initial pressure of fluid in the cylinder, a variable cut-off valve controlling-the period of admission of fluid to the piston, a governor or regulator connected with and controlling the degree of opening of the supply-valve, and a governor or regulator connected with and controlling the period of opening of the variable cut-olf valve reversely to the degree of opening of the supply-valve, substantially as set forth.

4:. In an engine actuated by expansive-fluid pressure, thecombination, with a cylinder and piston, of a supply-valve controlling the ICC initial pressure of fluid in the cylinder, a govthe throw of the eccentric reversely tothe deernor or regulator connected to and controlgrce of opening of the supply-valve, substanling the degree of opening of the supply-valve, tially as set forth.

a distribution-valve actuated by an eccentric BENJAMIN BRAZELLE. of variable throw and controlling the admis- Witnesses: sion of fluid to the cylinder, and a governor SIM T. PRICE,

or regulator connected to and adapted to vary CHRISTIAN F. SCHNEIDER.

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