US546096A - Compensating mechanism for direct-acting steam-pumps - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1.

. J. P. FRIZELL. I GOMPENSATING MECHANISM FOR DIRECT ACTING STEAM PUMPS.

No. 546,096. Patented Sept. 10, 1895.

AN DREW EGRANAM. FHUTO-UTRC WASHINGTON. In;

2 -Sheets--Sheet 2f (N-0 Model.)

J. P. FRIZELL. GOMPENSATING MECHANISM FOR DIRECT ACTING STEAM PUMPS No. 546,096. Patented Sept. 10,1895.

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JOSEPH P. FRIZELL, OF BOSTON, MASSACHUSETTS.

COMPENSATING MECHANISM FOR DIRECT-ACTING STEAM-PUMPS.

SPECIFICATION forming part of Letters Patent No. 546,096, dated September 10, 1895..

Application filed October 29, 1894. Serial No. 527,141- (No model.)

To all whom it may concern:

Be it known that I, J OSEPI-I P. FRIZELL, of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Compensating Mechanism for Direct-Actin g Steam-Pumps, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to compensating mechanism for direct-acting steam-pumps or similar engines wherein pressure of the steam or actuating fluid acts directly against the load to be moved, and is embodied in mechanism whereby mechanical energy is stored in the first part of the stroke of the piston in which steam acts with full boiler-pressure and is given out during the last part of the stroke when admission of steam from the boiler is cut off and the steam is acting expansively on the piston.

Direct-acting engines have been devised in which links connected with the piston-rod to act as a toggle-lever in conjunction with the said piston-rod and with an extraneous force applied in such manner that the toggle-lever will be straightened during the first half of the stroke, overcoming the extraneous resistance and storing force therein which is substantially given out in the last half of the stroke and applied through the toggle-levers so as to impel the piston-rod in the same direction to thereby assist the pressure of the steam in the last half of the stroke.

The present invention is intended as an improvement on apparatus of the character above referred to,and consists, mainly, in de vices that will be described whereby the line of action for the toggle-levers is shifted at each stroke, so that the extraneous force may act to resist the movement of the piston-rod in a fraction of each stroke less than one-half thereof and may assist the pressure of the steam in the remainder or greater portion of each stroke as is required in order to produce a sufficiently-uniform actuatingpressure on the pistonrod with a considerable expansive action of the steam.

Figure 1 is a side elevation of a direct-acting steam-pump provided with acompensating mechanism embodying this invention; Fig. 2, a diagram view showing the partsin different positions assumed in the stroke, and

Fig. 3 a side elevation showing a modified construction of the compensating mechanism embodying this invention.

The compensating mechanism forming the subject of this invention may be applied to any direct-acting engine in which the steam or actuating fiuid acts against a substantially uniform back-pressure or load, being shown in this instance as applied to a direct-acting engine comprising a steam-cylinder aand a pump-chamberb, the pistons of which are connected directly by piston-rod c in the usual manner.

In order to enable the steam to be used expansively or under conditions in which it exerts in the first part of the piston-stroke a pressure considerably in excess of the backpressure or load and in the last part of its stroke a pressure considerably less than the back-pressure, the engine is in accordance with this invention provided with compensating mechanism, comprising a pair of arms cl d pivotally connected with the piston-rod or with a suitable'yoke or cross-head e fastened thereto and connected at their outer ends by linksff with a device adapted to exert a pressure against said arms. The arms 61 cl thus constitute, substantially, a toggle-joint or toggle-lever, which when the piston is near the end of its stroke is bent and which is straightened as the piston-rod moves from the end of its stroke toward an intermediate point therein and is subsequently bent again during the latter part of the said stroke. As shown in this instance, the resistance to the straightening of the toggle-lever, which also acts as a force tending to bend the same, is derived from a piston g operating in a cylinder it, one end of which is connected, as by a pipe 2', with the condenser of the engine, so as to produce a partial vacuum in the cylinder at that side of the piston, while the other side communicates with the atmosphere through a passage 70, provided With an inwardly-opening check-valve M, which admitsair to the cylinder when the pressure on the adjacent side of the piston is less than the atmospheric pressure, but prevents the air from escaping when the pressure at that side of the piston is greater than the atmospheric pressure. Thus when the compensating piston g is ICO in operation.

caused to make its stroke by the straightening of the toggle-joint (Z (Z the air confined in the cylinder which was at atmospheric pressure at the beginning of said stroke of the piston is compressed and exerts an increasing resistance to the movement of the piston as the latter travels up to the pointat which the toggle-joint is straightened, after which the continued movement of the enginepiston permits the toggle-joint to be again bent, and the pressure of theairconfined in the cylinder 7?. acts on the toggle-joint tendingto bend the same and thereby tending to impel the engine piston-rod in the direction in which it is traveling. Thus in the first part of the stroke of the piston of the pumping-engine the pressure of the steam not only has to overcome the load to be operated upon, but also through the toggle-joint operates to compress the air in the cylinder h, and thus only a portion of its pressure is applied to overcome the load on the engine, and the steam-pressure is therefore necessarily greater than that required to overcome the load, but during the last part of the stroke the power that was applied in compressing the air in the cylinder h is given out by said air in expanding and is applied to the pistonrod and pumping-engine, so as to assist the pressure of the steam in overcoming the load, thus enabling the steampressure at this time to be less than the resistance of the load to be overcome, the result being that the steam may be used at a high pressure during the first part of the stroke, and admission of steam may be then cut off from the engine-cylinder and the steam permitted to work expansively to a pressure less than that of the load to be overcome, although suflicient in connection with the assistance afliorded by the compensating mechanism to overcome said load, and thus keep the engine It is further necessary to guide the extremities of the arms (Z 01 so that the thrust of said arms will be applied directly from the piston-rod to the resistance afforded by the compensating piston g. In order to attain this end and also to alford effective compensation with a short cut-off of the steam in the engine-cylinderfor example, atfrom onefourth to one-sixth stroke-the outer ends of said toggle-arms (Z d are connected with two pairs of radius-bars n a one pair at each side of said toggle-arms, and each of said radius-bars is connected with an arm n 71 pivotally connected with the framework of the engine. Thus the arms 11 n constitute movable supports for the radius-bars 11 02 and said arms are further controlled by pawls 0 0 weighted or otherwise constructed to normally fall out of engagement with the corresponding arms, as shown at the left hand in Fig. 1 and at the right hand in Fig. 2. The said pawls are, however, provided with lifters 0 shown as yielding projections, which are engaged by the cross-head 6 when the piston-rod arrives at the end of its stroke, as indicated in dotted lines, Figs. 1 and 2, so that the pawls just at the end of each piston-stroke and beginning of the return stroke are held up in engagement with the arms n or a as the case may be. The radius-bars, with their movable supports and means for controlling the latter, thus constitute shitting guides for the set of toggle-arms d (1 which, by the shifting of said guides, are caused to transmit force or pressure from the piston to the compensator during less than the first half-stroke of the piston and to transmit force or pressure from the compensator to the piston during the remainder or more than the last half of the piston-stroke, meaning by compensator the device that affords a pressure against the outer end of the toggle-arm tending at all times to impel the same toward the pistonrod.

The mode of operation is as follows, referring to Figs. 1 and 2, where byfull and dotted lines the positions assumed at several points in the stroke from right to left2'. e., in the direction of the arroware indicated: At the beginning of said stroke the parts are in the position indicated diagrammatically by dotted lines, Fig. 1that is, the arms 07. are engaged by the pawls 0 o and the arms dd are at an acute angle and the radius-bars n are nearly parallel with the piston-rod. Then as the piston-rod begins its stroke it tends to straighten or increase the angle between the arms 61 (1 the outer ends of which thrust against the ends of the radius-bars n and are caused thereby to swing in the are about the joint betweenthe radius-bars n and arms n as a center, the arms 01 at the other end at this time being free, so that said arms and the radius-bars a permit the outer ends of the arms (Z d to travel about the center stated and thus to move from a point nearly in line with the middle of the stroke of the crosshead 6 to a point nearer the end from which the stroke is being made, as clearly appears from the dotted and full line positions shown in Fig. 1. Up to the time when the arms 61 d are straightened or the cross-head 6 comes in line between the outer ends of said arms the pressure on the piston-rod applied through the said arms cl d keeps the radius-bars Win a state of tension and holds the arms at in engagement with the pawls 0 0 but as soon as the cross-head e has passed the position at which the arms 61 d were straightened, as is shown in Fig. 2, the resistance applied through the links ff and nowacting through the arms (1 d to thrust the piston-rod in the direction in which it is moving puts the radiusbars n in a state of compression, throwing the arms 71 back from engagement with the pawls 0 0 which now drop, as shown at the right hand in Fig. 2, the said arms n bring ing up on suitable abutments p on the framework, which thus resist the thrust of the radius-bars n Thus it will be seen that the upper radius-bar n and upper arm 01 and the lower radius-bar n and lower arm d consti- ICC IIO

tute toggle-levers, the joint of which is acted upon by the force from the compensating piston g, tending to straighten them and thus to apply their thrust to the piston-rod with a tendency to move it in the direction in which it is being impelled by the steam, the said thrust being exerted between the cross-head e and the abutmentsp. At the end. of the stroke the parts are brought to the position shown in dotted lines, Fig. 2, the radius-bars n n at the two sides of the toggle-arms d 61 being nearly in line, the arms n n hanging in substantially vertical position, and the pawls 0 0 at the end where the cross-head c has just arrived at the completion of its stroke being held up in engagement with said'arms a while those at the other end are dropped so as to disengage the corresponding arms n Thus in the return stroke from left to right the radius-bars n will guide and control the operation of the toggle-levers, while the radius-bars n will be substantially idle, but will be brought at the completion of this stroke in position to control at the next succeeding stroke. By thus having the outer ends of the toggle-arms d d guided by the radius-bars n n which are of a length only equal to about one-half of the length of the stroke and are controlled as described, it will be seen that the piston-rod acts to overcome the resistance of the compensating device duringless than one-half the stroke, as the arms (Z d will be straightened and their effect on the compensating resistance completed before the piston-rod arrives at the middle of its stroke and immediately thereafter, and thus during more than the last half of the stroke the said compensating force stored or overcome in the first part of the stroke will act to assist the piston in overcoming its load.

It will be obvious from the foregoing that either one of the arms d d without its mate would operate in substantially the same way, except that it would bring a lateral thrust on the piston-rod which might be sustained by a suitable guide for the cross-head, as shown in Fig. 3. The invention therefore is not limited to the construction in which a pair of arms, as d d are used; but the said construction employing a pair of arms is preferable, as by this arrangement the applied forces are well balanced, producing a pressure or strain onlyin line with the movement of the pistonrod and against such portions of the framework as are designed to withstand strains in the engine without regard to the compensating mechanism.

The compensating force is applied with such variations as will substantially supplement the variations in the steam-pressure when the engine is working with an economical cut-off, thus giving a uniform steady movement of the piston when acting against a constant load.

The compensating mechanism herein described is adapted to be applied to a single direct acting engine or pump and it renders a pump of this kind very efficient.

It is obvious that any other source of continuous force-such, for example, as the force of gravity or that of a springmight b66111- ployed to act on the outer ends of the arms d d as a compensating force; but the force derived from the compression of air, as herein described, gives such variations in pressure as are desired, and the said compensating piston and cylinder are believed to constitute the most satisfactory means for producing the compensating pressure.

I claim- 1. The combination with the piston rod of a direct acting engine and an arm connected at its inner end with the said piston rod, and a compensator for applying a compensating force to the outer end of said arm with shifting guides for the outer end of said arm, whereby the latter transmits pressure from the piston to the compensator during less than the first half stroke of the piston and transmits pressure from the compensator to the piston during the remainder of the piston stroke, substantially as and for the purpose described.

2. The combination with the piston rod of a direct acting engine of an arm connected at its inner end with the piston rod, and at its outer end guided in a path transverse to the line of movement of the piston rod, and a compensator comprising a cylinder and piston therein, said cylinder being connected at one end with a vacuum pipe and provided at its other end with a passage to the external atmosphere, and an inwardly opening check valve in said passage and means for connecting said piston with the outer end of said arm, substantially as and for the purpose described.

3. The combination with the piston rod of a direct acting engine of an arm connected at its inner end with the piston rod, and means for applyinga compensating force to the outer end of said arm, a radius bar connected with the other end of said arm; an arm pivotally connected with said radius bar, and with the frame Work, and means for locking and releasin g said arm, substantially as and for the purpose described.

4. The combination with the piston rod of a direct acting engine of an arm connected at one end with the piston rod and means for guiding the outer end of said arm in a path transverse to that of the piston rod, and a stationary compensating cylinder and piston therein, and connections between said piston and the outer end of said arm, said cylinder being provided at one end with a passage to the external atmosphere and an inwardly opening check valve therein, and otherwise completely closed, said piston thus operating to compress the air confined in said cylinder during the movement of said piston in one direction, and being actuated by the expansion of said compressed air in the return move ment, substantially as and for the purpose described.

5. The combination of the piston rod with the arms d, d each connected at its inner end with said piston rod and means for applying a compensating force to the outer ends of said arms, the radius bars n n connected with the outer ends of said arms, armsn n pivotally connected with said radius bars, and

[O with the frame work; and the pawls 0, 0 cooperating with the said arms n n and controlled by the piston rod, substantially as and for the purpose described.

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

JOSEPH P. FRTZELL. Witnesses:

J 0s. P. LIVERMORE, M. E. HILL.

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