US703968A - Steam-pump. - Google Patents

Description

No. 703,968. Patented July '1, I902;

P. F. ODDIE.

STEAM PUMP.

(Application filed Oct. 1, 1900.!

(No Model.)

' Wbwwes= Inventor: W 5 5? MM flZTorneyS.

UNITED STATES ATENT OFFICE.

PHILIP FRANCIS ODDIE, OF WIMBLEDON, ENGLAND.

STEAM-PUMP.

SPECIFICATION forming part of Letters Patent No. 703,968, dated July 1, 1902. Application filed October 1, 1900. Serial No. 31,698. (No model.)

To aZZ whom it may concern:

Be it known that I, PHILIP FRANCIS ODDIE, engineer, of Wimbledon, county of Surrey, England, at present of Oschersleben, Germany, have invented new and useful Improvements in Direct-Acting Steam-Pumps, of which the following is a specification.

My invention relates to improvements in direct-acting steam-pumps in order to increase their economy in working by enabling them to work with what is technically known as expansion.

In the ordinary direct-acting pumps without a fly-wheel the steam admission must be continued to practically the end of the stroke,

for since the work on the plunger is constant the pressure onthe motor-piston must also be constant. In some forms of direct -acting pumps in order to be able to work expansively oscillating auxiliary cylinders containing water or air under pressure have been used, the piston ends being attached to the piston-rod. These cylinders and pistons take up the excess of work at the commencement of the stroke and give it back toward the end, when the steam-pressure has fallen below the water-pressure. These oscillating cylinders are complicated and expensive to construct and set up and have been found difficult'to maintain in proper working order, owing to leakage at the trunnions, through which the working fluid must pass and'on' which the cylinders are mounted. In this invention, however, I dispense with oscillating cylinders altogether, as also with pistons or plungers directly connected with the piston-rod, and pro vide instead one or more fixed auxiliary cylinders placed at approximately right angles to the plane of motion of the pump pistons or plungers. Each cylinder is provided with a piston or plunger under pressure and with means for increasing the eifective power of the compensator in the middle of the stroke of the steam-pump. For this effect the end of the compensator-cylinder is connected to any air or steam orgas reservoir, and a suitable valve is arranged in the passage connecting the reservoir to the auxiliary cylinder. I have conclusively proved by many experiments that without such an arrangement of a valve no compensator with fixed cylinders and levers can work at all satisfactorily.

In the accompanying drawings, Figure l is a longitudinal section through one form of my invention. Fig. 2 is a diagram showing the Work ofthe auxiliary cylinder. Fig. 3 shows a modification in which the valve behind the piston of the auxiliary cylinder is opening outwardly; and Fig. 4 is a detail view showing the adjusting means, to be hereinafter described.

Referring to Fig. 1, each auxiliary cylinder at has a plunger 1), and its rear end is connected by a passage q-to-any reservoir filled with steam, compressed air, or the like. The plunger presses constantly on the point of articulation fof two links 0 and a without being directly connected with the. plunger 11. The other end of thelink c is connected with the cross-head d of the steam-pump or steamcylinder, While the other end of the link 6 is pivoted at g on the flange orany other part of the frame. It is preferable to arrange the pivot g of the link 6 so that it may be adjusted as indicated in dotted lines. Thus there is no pressure on the sides of the plunger-cylinder no matter What angle the links take up with reference to the axis of this cylinder.

Inoperation when the pump-piston is about to commence its stroke say from left to right-the cross-head d is at its inward position, so that the center of the cross-head is at the point y. The axis of linkcis at an oblique angle thereto, as indicated by y, and that of the other link e is parallel with the piston, as indicated by 3 the plunger I) constantly pressing onthe articulation-point f, which is now at its lowest position, (indicated by 1 The steam-piston now commencing to move under excess of steam over Water pressure communicates this excess of pressure through link e to the point of articulationf, which in rising forces back the plunger 1). The velocity with which the point f rises, and consequently with which the plunger is forced back, gradually decreases until half-stroke of the driving-piston is reached, when the plunger 1) comes to'rest in'its inward motion, which position is that shown in Fig. 1. From this middle position to the end of the stroke the point f commences to fall with an increasing velocity, communicating an ever-increasing pressure in the direction of the piston-rod path until the end of the stroke has been reached and the cross-head dis at its extreme outward position, as indicated by y, when the point of articulationfis again at itsv lowest position. In this moment the link 0 has the position shown by the dotted line 1 while the pointfis again in the position 1 Thus the work done by the excess of steampressure at the commencement of the stroke is given back during the last part, when the steam-pressu reis reduced by expansion. The same action is repeated in the opposite direction during the return stroke of the pumppiston. It will be observed that the force acting on the plunger 1) is resolved into two forces, one acting along the axis of link a and the other along the axis of the link 6, and that the compensating force increases in proportion as the angles made by the axes of the link 8, c, and 6 decrease after halfstroke. Further, it will be seen that in order that the compensating force may be equal on the forward and backward strokes the angles a and and a must also be equal at equal corresponding points of the inward and outward strokes. Now this angle depends on the position of the pivot g of link e, which is adjustable. If, therefore, as is frequently the case with direct-acting pumps without a fixed limit to the stroke, the piston should make short strokes at one end or the other, such defect can be easily remedied by raising or lowering the pivot g. Thus if, for example, the pump is making short strokes in its forward motion by raising the pivot g the angle a, made by the axes of the links, would be decreased, and consequently the compensating action would be increased in this direction and decreased in the other. Experience has proved that in the case of the adjustability of the pivot g of the link 6, as before described, the adjustment is considerably improved when the pivot g is displaceably arranged not in a vertical line to the piston-rod, but parallel with the latter or inclined to it. This is efiected by arranging the track on which the device carrying the pivot g is movable at an angle to the piston-rodas, for instance, by making the flange t as shown in Fig. 4.-. The same end may be obtained by making the link 6 in two parts, the combined length of which can be regulated by means of a right and left handed screw-threaded sleeve u.

Finally, it is possible also to adjustably arrange the cross-head d in relation to the piston-rod wsay by an arrangement according to which exchangeable washers 'v of varying thickness are placed between the cross-head and its rod.

In the work-diagram shown in Fig. 2, m is the work-diagram of the steam-cylinder, n the diagram of the pump, and 19 that attained by using the auxiliary cylinders a and a constant pressure behind the piston b. It is evident that the latter do not fully equalize the differences between the diagram of the steamcylinder and the pump. The ideal working,

which is shown by the diagram 0, however, maybe obtained with absolute exactness when the pressure behind the piston is rendered variable-i. e. when some compressible fluid, such as compressed air or steam, is employed. The end of the cylinder is therefore connected with a chamber containing some compressible fluid, such as steam or air. It is therefore possible to connect the conduit q, leading from the cylinder behind the piston, with the slide of the steam-cylinder or with the chamber of the high-pressure conduit or, finally, with a special reservoir, into which air is constantly driven by means of a small air-pump or any other suitable device. The conduit from the back of the plunger-piston q is closed by means of a valve 1", which can open either inwardly or outwardly. In one arrangement, which is shown in Fig. 1, the valve opens into the cylinder and is introduced for the purpose of admitting air during the downstroke of the piston, which air is compressed in the course of the upstroke of the piston. In the next downstroke of the piston the valve 1' will be reopened at the close of the downstroke, so as to allow as much air to enter as may have been lost during the preceding course of work, owing to any leakage which may have taken place. It is necessary that there should be a constant pressure in the passage q of about four atmospheres. The valve being pressed on its seat by a spring in the course of the upstroke of the piston, the air or compressible fluid contained behind the piston is compressed to between twelve to eighteen atmospheres.

In the modification according to Fig. 3 the valve nopens into the conduit q. Here the pressure at the back of the piston 19 is balanced by the pressure existing in the conduit only when the piston is working through its upper course. For this purpose the valve ris provided with a small projection 3, against which the piston strikesin the course of its upward movement, thereby raising the valve for a moment. The same result-that is, the diagram omay be obtaiued,however,by connecting the cylinder a to a reservoir partly filled with air and partly with oil. The oil acts on the piston while the air is acting on the surface of the oil. The oil when forced out from the cylinder and entering the reservoir compresses the air therein. The oil or other liquid in the reservoir serves two objects-first, by altering the level of the liquid the size of the air-chamber or clearance-space can be reduced or enlarged at will, and consequently the difference of pressure between the middle and the ends of the stroke exactly regulated to suit any given steam pressure and ratios of expansion in the main steamcylinders; secondly, the liquid forms a seal around the plunger, and thus prevents airleakage through the stuffing-box gland.

Having now particularly ascertained the nature of my said invention and the manner it may be performed, I declare what I claim is- 10 ting against the free ends of said jointed levers, a reservoir connected to said auxiliary cylinder, and a valve interposed between said cylinder and reservoir. i

In testimony whereof I have signed my name to this specification in the presence of [5 two subscribing witnesses.

PHILIP FRANCIS ODDIE. Witnesses:

MAX EICHINBERG, CARL OSTERMANN.

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