US514333A - normajsto - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1..

A. NORMAND. STEAM ENGINE ATTACHMENT.

Patented Feb. 6, 1894.

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Patented Feb. 6,. 1394.

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AUGUSTIN NORMAND, 0F HAVRE, FRANCE.

STEAM-ENGINE ATTACHMENT.

.SPECIFGATION forming part of Letters Patent No. 514,333, dated February 6, 1894.

Applicationiiled September 5,1893. Serinlll'o. 484,861. -tNo model.) Patented in France July 29, 1887, No. 185,071; in England July 29, 1887, No.10,545, and in Belgium September 3,1889,No. 87,605.

To @ZZ whom it may concern/.-

Be it known that I, AUGUSTIN NORMAND, a citizen of France, and a resident of Havre, in the Department of the Seine-Infrieure, France, have invented a new and useful Improvement in Steam-Engine Attachments, (for which I have obtained patents in France, No. 185,071, dated July 29, 1887; in Great Britain, No. 10,545, dated July 29, 1887, and in Belgium, No; 87,665, dated September 3, 1889,) of which the following is a specification.

The compression of the steam at the end of the stroke of the piston presents the advantages, as is well known, of neutralizing entirely or partially the prejudicial influence of clearance and of heating the surfaces of the cylinder which come in contact with the entering steam and also of enabling the engine to runat high speeds which would otherwise When the exhaust and admission of steam are controlled by a single valve it appears impossible, with the arrangements ordinarily employed, 'to vary the expansion without producing corresponding changes in the compression. Consequently the compression cannot be regulated properly for all conditions of expansion. When the Stephenson link motion, or other analogous arrangements are employed the degree of compression increases rapidly with the ratio of expansion, and even when a special or separate slide valve is employed for the exhaust, there is always a risk of the slide being slightly out of order andfwhen this occurs the compression may become excessive so that the pressure of the steam in the cylinders is liable to rise much higher than that in the valve chest. This is especially the case with the high pressure now used, where a few degrees of superheating will prevent steam from condensing without a large increase of pressure.

In order to provide against this danger and obtain from compression all the advantages that it presents in theory, and render it independent of the ratio of expansion, the cylinders of steam engines constructed according to this invention are provided with safety valves so arranged as to blow off into the valve chestinstead of into the open air. This renders it impossible for the pressure within the cylinder ever to greatly exceed that in the valve chest and the steam being blown ed into the valve chest is not wasted. The loss of power resulting from this arrangement is little er none, as the opening of exhaust is delayed, and in any case the portion of the curve of the indicator lost by the compression when the engine is working with great expansion, corresponds with the end of the stroke where the useful effect produced upon the crank shaft is almost ml. The safety valves are pressed to their seats by the pressure existing within the slide valve chest so that anV extremely slight spring is sufficient to insure perfect contact with the seats, and a prompt closure directly the excess of pressure which has opened or lifted, the valve is removed. Moreover the period of time available for closing the valve is always sufficient even when the engine is running at a high speed, as it is equal to that comprised between the admission and the cut off of steam.

Valves which are almost noiseless in-their action are now employed in air pumps, and it is evident that the same or analogous arrangements may be employed in the present case with like results. Moreover there is not the same tendency to produce a loud noise as there is with ordinary valves which require to be heavily loaded. By making the joint of the valve with lead or other but slightly elastic substancea noiseless action can beinsured. Slide valves arranged to lift slightly in case of an excess of pressure inthe interior of the cylinder could'not be employed with the same effect, as the rubbing surfaces would wear out rapidly, and the noise produced would be objectionable. These new valves enable the ordinary safety or blow off valves of the cylinders to be dispensed with. They suffice to let off any water that may accumulate in the cylinders, a single blow off cock being placed on the valve chest.

Figure l of the accompanying drawings represents a section of a part of a steam engine constructed according to this'invention, the section being taken along the line I J, Fig. 2. Fig. 2 is a section taken along the line K L, Fig. 3, and Fig. 3 is a section taken along the line M N, Fig. 2. Fig. 4 represents one of the blow off valves in a section taken along the line O l? Figl 3.

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one hand with the interior of the cylindery through passages E E Figs. l and 2, and open directly into the steam chest on the other hand as indicated in the drawings.

Having now particularly described and ascertained the nature of the said invention and in what manner the same is to be performed, I declare that what I claim is- The combination with an engine cylinder having a valve chest, supply passages B for the cylinder, and an exhaust C, of independent blow-0E valves arranged respectively at opposite end portions of the cylinder and communicating by passages E, which are independent'of the passages B, with the cyllnder, said valves being unseated by pressure in the cylinder and blowing o into the valvechest, substantially as and for the purposes described.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

AUGUSTIN NORMAND. Witnesses:

C. B. PIKE, G. OARTING.

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