US2138740A - Steam engine valve - Google Patents

Description

Nov. 29, 1938. w. F. KIESEL, JR 2,138,740

STEAM ENGINE VALVE Fil ed Aug. 29, 1936 OOOOQOQOOOOOOOG 0000000 00000000 0 000000000 3 300000000033 000 00 00 Patented Nov. 29, 1938 UNITED STATES PAT QFFEE or of one-third to Virginia Kiesel Rutan, Chevy Chase, Md., one-third to John S. Kiesel, Williamsport, Pa., and

one-third to William F.

Kiesel, 3d, Stewart Manor, Long Island, N. Y.

Application August 29, 1936, Serial No. 98,615

9 Claims.

This invention relates to steam engine valves and more particularly to valves for use with variable speed steam engines such as those used on locomotives.

The general object of the present invention consists in providing a novel and improved valve for steam engines. More particularly it is an object of the invention to provide a valve for locomotive steam engines in which early eifective cutoif for high speed operation is accomplished without corresponding change in either the timing of the exhaust events or the size of the effective exhaust ports.

An important feature of the invention consists in the provision of a slide valve for steam engines in which the effect of earlier cut-off and the consequent reduction in steam consumption is pro duced by a. throttling action resulting from the proportioning of the valve and its chamber so that .at low speeds full steam is supplied and at high speeds the quantity is automatically reduced whereby the valve can be operated to produce at all times the desired release and compression timing.

Another important feature of the invention consists in the provision of an inside admission piston valve for locomotives in which the barrel of the valve has such a clearance in respect to the reduced ported ends of the valve chamber that the flow of steam to the ports is restricted to an area not greater than 3% of the flue area of the locomotive nor greater than of the port area of the cylinder.

Still another important feature of the invention resides in the manner of constructing the body or barrel of the reciprocating valve, this body being preferably formed from a straight tube having the ends upset to form a substantial T in cross-section to receive and position the 40 bull ring, packing rings, and the spider.

A further object of the invention consists in the method of operating a locomotive by the use of a slide valve and throttling the steam flow by the valve construction whereby wide open exhaust ports and properly timed release and compression can be had as well with early effective cut-off as with late cut-01f Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawing and following specification wherein is disclosed a single exemplary embodiment of the invention with the understanding that such variations and changes may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawing:

Figure 1 is a longitudinal section through a portion of a steam engine cylinder and through the valve and chamber therefor; and

Figure 2 is an enlarged central longitudinal section through one end of the valve itself.

Fig. 3 is a transverse sectional view of a locomotive in which the invention is embodied.

The well-known slide valve as used in most steam engines is quite satisfactory for constant speed operation for which it can be designed and set to provide satisfactory timing of the four major events in the operation of the piston of the engine. Admission or opening of the valve can be arranged just prior to dead center to start the flow of steam sufficiently early to have it become effective as soon as the piston starts on the return stroke'and cut-off of the steam can be arranged to provide the desired expansion and either maximum economy, maximum power or some optimum condition. Release can be set a predetermined amount prior to opposite dead center and compression adjusted to the proper amount to absorb the unbalanced energy of the piston and start it on its return stroke.

Unfortunately such a valve does not lend itself well to variable speed and variable power operation for the four events are so correlated, because of the unitary valve structure, that no one of them can be changed by a mere setting of the valve or adjustment of its gear without changing all of them. Thus when it is desired to run at fairly high speeds with early cut-off and using a valve designed for variable speed operation, there is excessive compression caused by the change of the valve position and at the same time because of the shorter stroke of the valve the exhaust ports are materially restricted and thus poor operation results.

Most engine designers have generally assumed that admission of steam by the valve into the cylinder should be as free as possible so that port areas and valve openings are designed and adjusted for this and every effort is made to obtain a relatively sharp cut-off indication on the indicator card. Now, when changing the setting of the Valve gear to run at very high speed, the valve travel is shortened by means of the reversing gear in order to advance the cut-off which also has the effect of making the exhaust closure earlier on the return stroke thereby materially reducing the port opening to the exhaust. The present invention is based on the knowledge that it is important to get rid of the steam in the cylinder with the least amount of back pressure and it is therefore assumed that the problem is not one of introducing steam into the cylinder but mainly of exhausting it as freely as possible. With this premise, the present invention, while relating particularly to locomotives, but not so restricted, has been made with the thought uppermost in mind that freedom of exhaust should take precedence over freedom of admission.

Locomotives of conventional design, and most of them use a single piston valve for each cylinder, develop excessive back pressure and compression in the main steam cylinders when running at high speed with the reverse gear hooked up for veryearly cut-off. Locomotive valves and gear must be designed for a late maximum cut-off in order to have sufficient starting power and the change in valve movement necessary to'advance the cut-off from, say, 75% or to 10% or 15% is quite considerable and the valve stroke is materially shortened. This results in the aforementioned excessive back pressure and compression, causing a bucking action in the. operation of the engine at the end of each return stroke. This produces rough riding, hot crank pins and journals, loss of power, and excessively high cost of maintenance of the locomotive. An experienced engineer tries to improve conditions as much as possible by partially closing the main throttle to permit him to use a somewhat later cut-off, with somewhat greater steam consumption in the endeavor to obtain a greater freedom of exhaust. Such operation is a decided help but does not permit realizing the maximum capabilities of the steam used.

The present invention permits a more efiicient use of the steam and at high speed and capacity automatically provides for earlier effective cutoff without shortening the valve stroke and does not reduce the port areas for exhaust. Referring now to the drawing, there is shown in Figure l a substantially conventional layout of cylinder, valve chamber, and valve for a locomotive. The cylinder l!) is provided with the piston H and mounts the valve chamber or steam chest i 2 provided with live steam from the dry pipe Hi to the central enlarged portion of the valve chamber M.

The valve chamber has reduced cylindrical ends l5 closed by caps 56, ll, one of which is arranged to pass the valve stem l8 through suitable packing; These reduced ends may themselves provide the working surface for the valve but it is preferred to fit them with sleeves, bushings or ferrules l9 each provided with a circumnferential ring of ports 20, the end surfaces of which are in parallel planes at right angles to the axis of the valve. Thisarrangement of the ports is not essential since for the purpose of this invention it is only required that the ports be closed simultaneously by the valve and if the valve has other than a right angled end, the ports can be arranged in keeping.

The ports Zil lead to a circular passage 2| which connects to the steam passage 22 leading to the corresponding end of the cylinder for providing steam against one end of the piston.

Exhaust steam coming from the cylinder through the passages 22 and 2i passes through the ports 28 uncovered by the end of the valve and escapes through ports 23 in the ferrule and into the passage 24 to a suitable exhaust pipe not shown. By virtue of the increased diameter of the ferrule at 25 and the limited valve travel, the ports 23 are not controlled by the valve.

The valve itself comprises a central barrel 26 having the large ends 21 each one fitted with an appropriate set of packing rings 28 and 29. These enlarged ends and the rings serve to control the flow of live and exhaust steam through the ports 29 and as the valve reciprocates it automatically supp-lies live steam to one end of r the cylinder and permits exhaust from the other end and vice. versa.

As described above the whole structure is conventional and the valve may be designed and initially set to provide the desired timing of the conjugate events for the piston at maximum cut-off. A feature of the present invention comprises enlarging the diameter of the valve barrel or body 25 so that the annulus 3i) between it and the inner working surfaces of the ferrules I9 is much less than the area conventionally allowed here.

In designing any steam engine the total area of the ports at each end is made such as to provide the freest possible flow of steam, both live and exhaust, in keeping with the speed of the engine and well-known formulas are used for the purpose. In the present invention the same formulas are used to compute the port areas which when the valve is set for exhaust are open fully. The live steam, however, coming from the dry pipe via the enlarged central portion M of the valve chamber must pass through the annulus 30 to reach the ports 20 when they are uncovered by proper positioning of the. respective end of the valve and this annulus restricts or throttles the flow of steam under certain conditions.

t is very convenient to measure locomotive capacity or rather boiler capacity for evaporation by flue area, the total area of boiler flues. In a well designed locomotive a maximum of about ten thousand pounds of water per square foot of net flue area can be evaporated. This flue area then forms a convenient basis for determining port sizes and in accordance with the present invention the annulus area 39 is restricted to less than 3% of the flue area, whereas the total area of all of the ports 2!) in one end of the valve.

chamber will be considerably greater. At slow speeds the restricted annulus area produces no material throttling of the steam since the piston moves slowly enough so that steam can be supplied as rapidly as the cylinder volume behind the pistonincreases. This permits the longest possible cut-oif for which the valve is designed with full power from full steam flow.

As the speed of the locomotive increases, however, the piston movement becomes so rapid that the volume behind it increases more rapidly than steam can flow into it without material loss of pressure through the restricted area 30 so that an increasingly reduced quantity of steam is provided to the cylinder as the speed increases. This has substantially the same effect as earlier cutoifs have since it permits greater expansion of the steam in the cylinder and a full realization of the work available from it. By properly designing the area 30 the equivalent of the desired early cut-off of present constructions is achieved. The

amount previouslymentioned of less than 3% of the flue area or an area of the annulus 30 somewhat less than that opened by the valve when at of the port width, i. e., the distance the valve must travel in moving from one edge thereof to the other, is found to be necessary for ordinary locomotive operation producing the desired throttling of steam during admission to get the equivalent of an early cut-off when the valve is travelling at high speed. This permits a longer valve travel for the same amount of steam admitted as achieved in the conventional construction thereby producing a much freer exhaust condition and permitting the compression to be approximately that desired.

With this construction it is not essential to have an adjustable valve gear except one that can be set for reversal since a setting for maximum power, i. e, latest cut-ofi, is proper for all speeds since the effective cut-off is automatically shortened as the speed increases thereby reducing the amount of labor on the part of the engineer and producing superior results not only in the proper adjustment of the cut-01f to the speed, but in maintaining at all times the proper exhaust conditions.

The use of the larger valve body or barrel permits of a simple construction of the valve by making this body 26 of a steel pipe or tube 40 of a type available in production. A simple upsetting operation enlarges each end of the tube as shown at 4! so that in cross-section it is substantially T-shaped having an inner peripheral flange 42 and an outer peripheral flange 43 providing the flat annular end 44 against which is abutted a portion of the packing ring 29 and the reduced inner end 48 of the bull ring which spaces the packing ring 29 and the packing ring 28 and provides the enlarged end 27 of the valve. The conventional spider 48 having the L-shaped flange 49 holds the ring 28 in position and fits closely to the inner surface of the bull ring and has its inner end 50 telescoped within the inner flange 42 on the end of the barrel. This construction eliminates the requirement for a special body which must be forged or cast and permits it to be manufactured or replaced quite simply from stock material.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a piston valve having inside admission, in combination, a valve body having enlarged ends operating in ported sleeves, said sleeves being connected by an enlarged steam chest, each of said valve ends providing conventional steam lap inwardly of said ports, said body being of such cross-sectional area between said ends that the steam passage space between it and the inner surface of either of said sleeves is less than onethird of the area of the ports in one of said sleeves, said passage space supplying all of the steam to the cylinder at all speeds of the engine.

2. In a piston valve having inside admission and outside exhaust, in combination, a Valve chamber having a bushing in each end thereof with live steam space therebetween, ports in said bushings leading to opposite ends of a steam engine cylinder, a valve in said chamber having a central body portion and ends closely fitting said bushings and cooperating with the ports therein to control the flow of live and exhaust steam therethrough, said valve body portion being circular in cross-section and having a radial spacing from the bushing walls of less than onethird of the width of said ports and for a dis tance from the cut-off edge of the valve end greater than the steam lap so as to be elTective in throttling the flow of steam at high engine speeds.

3. In a piston valve having inside admission and outside exhaust, in combination, a valve chamber having a bushing in each end thereof with live steam space therebetween, ports in said bushings leading to opposite ends of a 'steam engine cylinder, a valve in said chamber having a central body portion in said live steam space and ends closely fitting said bushings and cooperating with the ports therein to control the flow of live and exhaust steam therthrough, said valve body adjacent said ends being circular in cross-section and spaced radially from the inner Walls of the corresponding bushing a radial distance less than one-third of the port width in either bushing and for an axial distance at least the port width.

4. In a piston valve having inside admission and outside exhaust, in combination, a valve chamber having a tubular bushing in each end thereof with a live steam space therebetween, a ring of circumierentially spaced ports in each of said bushings and leading to the steam passage for the corresponding cylinder end, the working edges of the ports of said rings being in circumferential alignment, a valve in said chamber having a central body portion in said live steam space and ends closely fitting said bushings and cooperating with the ports therein to control the flow of live and exhaust steam therethrough, each of said ends cooperating simultaneously with the working edges of its ports, said valve body adjacent said ends being spaced radially from the inner walls of the corresponding bushing a radial distance less than one-third 01' the axial distance between the working edges of any one of said ports but sufficiently great to supply all of the working steam required by an engine piston at all speeds thereof.

5. In a piston valve having inside admission and outside exhaust, in combination, a valve chamber having a tubular bushing in each end thereof with a live steam space therebetween, a ring of circumferentially spaced ports in each of said bushings and leading to the steam passage for the corresponding cylinder end, and a valve in said chamber having a central body portion in said live steam space and ends closely fitting said bushings, the inner edges of said ends and the inner working edges of said ports being so arranged that admission and cut-off each take place simultaneously at all ports in a bushing and that conventional steam lap is provided, said valve body adjacent said ends and lap providing portions being of such cross-sectional area in respect to the surrounding bushing as to produce substantial throttling of all of the steam flowing to the ports at engine speed to automatically produce the efiect of early cut-off. 6. In a piston valve having inside admission,

I in combination, a steam chest, a ported sleeve at each end thereof, a valve body having enlarged ends operating in said sleeves to open and close said ports, said ends providing normal steam lap, said body between said lap producing portions of said ends being of such cross-sectional area that flow of steam to open ports at high engine speeds is reduced to a fraction of the port capacity to automatically produce the eiTect of early cut-off, said area producing substantially no throttling at low engine speeds.

'7. In a piston valve having inside admission, in combination, a valve chamber having spaced, reduced, cylindrical, ported portions with live steam space therebetween, a valve in said cham* her having ends working in said portions to open and close the ports and a central body portion in said live steam space, said body being of such size for at least a distance equal to valve stroke adjacent the cut-off edge of each end that the space between it and the ported portions of said chamber is a steam passage of less than 3% of the flue area of the boiler supplying the steam to the valve,

8. A valve of the piston type for use With a locomotive having a boiler of definite flue area, a cylinder and steam passages from said boiler to cylinder of standard capacity, said valve being positioned to control the flow of steam to said cylinder and comprising, in combination, a valve chamber having a central, live steam space and spaced, reduced portions, ported in accordance with standard practice to pass the required amount of steam for maximum power output, a valve in said chamber having ends working in said portions to open and close the ports to said live steam space, and a body portion of such size near said ends that in cooperation with the walls of the said reduced portions it always restricts the steam passage to not more than 3% of said flue area.

9. A piston valve having a barrel, a bull ring and spider at each end of said barrel, a spindle connecting said spiders, said barrel consisting of a straight tube having its ends upset to provide inner and outer peripheral'fianges merging into a flat annular end, each bull ring spacing a pair or" packing rings, a flange on each spider engaging the corresponding bull ring and a packing ring, a cylindrical portion on each spider telescoped into its bull ring and the corresponding inner barrel flange, said flat annular end engaging the second packing ring and the bull ring and said spindle clamping the whole together.

WILLIAM F. KIESEL, JR.

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