US1970324A - Locomotive valve mechanism - Google Patents

Description

Aug. 14, 1934.

W. F. KIESEL, JR

LOGOMOTIVE VALVE MECHANISM Filed March 5, ,1931 I 2 Sheets-Sheet l Aug. 14, 1934.

W. F. KIESEL, JR

LOCOMOTIVE VALVE MECHANISM 2 SheetsSheet 2 iled March 5, 1931 Patented Aug. 14, 1934 imit 9 Claims.

1,970,324 LoooMo'rIvs VALVE MECHANISM William F; Kiesel, J12, Holliday'sburg, Pa. Application March 5,1931, Serial No. 520,444

This invention relates to valves for steam engines and particularly to valves for the steam engines of locomotives using high boiler pres- It is a general object of the present invention to provide novel and improved valves and valve operating mechanism for locomotive engines.

More particularly it is an object of the invention to provide, in a steam engine, a main valve adapted to control all four cylinder events with an auxiliary cut-oil valve having nominal cut-oil.

together a fixed An important feature of the invention comprises the construction of the cut-ofi valve and tling action is effected which, at high speeds,:re-

duces the flow of steam so that a quantity of steam equivalent to a shorter cut-off is delivered' A further'feature of the invention resides in actually for each engine with means to drive th e cut-off.

valves in direct relationship to the piston movements, together with means for connecting the passages between the valves of each engine to'-' gether for the delivery of a limited quantity of steam to the main valves after out-oil by the for high speeds.

independent cut-off valves.

A still further feature of the invention resides in the novel arrangement of mechanism for driving the cut-off valve in direct relationship to the movement of the piston.

standing, however, that such changes may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

Figure 1 is a side elevation of the forward part of a locomotive showing the cylinder, valves, piston rod, driving rod and valve operating mechanism;

Figure 2 is a transverse section of the locomotive, the righthand portion being taken on line 2-2 of Figure 1 and the .Eefthand po line 2'2' of Figure 1-;

rtion on Figure 3 is a longitudinal section through the two valves for one cylinder of the locomotive and taken on line 3-3 of Figure 4a; and

Figure 4 is an elevation of the rear end of a cylinder and the associated valves and showing the valve operating levers in position.

The realization of a high percentage of the ,fullexpansion possibilities of high pressure steam is extremely difficult, when using but one valve per cylinder, in a high-pressure steam locomotive. On account of their interrelation, it is difficult to attain the desired valve events at very early cut-oii with the conventional single valve of the D or piston type with the usual operating gears,and then only for a limited-range of speed.- A change of hook-up, varying the cut-off also carries with it a definite change in release and compression, which may be quite undesirable at the speed at which the locomotive is running. Hence, the designer is compelled, as a compromise, to make the valve events as good as possible, for an intermediate speed, resulting in less favorable conditions for higher or lower speeds.

Pre-admission should increase with speed, but release should be as late as possible. Hookingup the valve gear to obtain very early cut-off reduces the valve travel, hence, also, the port openings for admission and release, resulting in too high compression at high speed, if proportioned for intermediate speeds, and too low compression for intermediate and low-speeds, if proportioned The present invention seeks to overcome the above diiiiculties by using an interposed cut-off valve of relatively small diameter and travel, op erating at a fixed cut-off together with a main valve which controls all four cylinder events, and is adjustable in the usual manner.

When running at speed (moderate to high) the amount oi steam used per stroke is measured out by the cut-off valve. This amount decreases with increase of speed, being throttled or wiredrawn by the limited port opening governed by the use of a valve of small diameter and stroke, resulting in the equi alent of an earlier virtual cut-off-with increase of speed. By increasing or decreasing the valve travel of the main valve, by means of the valve motion mechanism, the operator can decrease or increase the compression, suitable to the speed at Whichhe is operating, without materially affecting the admission expansion pressure. Hence, at speed, the operator has practically no control of steam admission to the cylinders, but, on account-of this relatively fixed steam admission, varying with the speed, can obtain more economical results by varying release and compression events through his control of the main valve and its link motion.

Referring now to the drawings, the invention will be seen illustrated particularly in connection with the righthand cylinder 10, of a locomotive, mounted upon the conventional saddle 11 and adapted to receive steam from the chamber 12 of the main valve through suitable passages 12' and 12 The main valve chamber 12 has mounted thereon the cut-off valve chamber 13 into which is connected the live steam inlet 14.

The piston 15 operates in the cylinder 10 and is connected by the rod 16 to the cross head 17 operating in the guide 18. The driving rod 19 is pivoted at 20 to the cross head and at20 to the driving pin on the driving wheel 21.

Referring now particularly to Figures 2 and 3 it will be seen that the main valve 22 operating in the chamber 12 is of the piston type, although this is not essential, and is .of the inside admission type. The valve is conventional and need not be further described here.

The independent cut-off valve operates in a sleeve 25 fitting in the casing or chamber 13 and this sleeve is provided with a series of radial ports 26 opening into the chamber 13 which communicates with the chamber 12 as will be presently described. The live steam intake 1 1 communicates directly with one end of the sleeve 25 as clearly seen in Figure 3 and since the piston valve 2'7 is an open ended tube, as shown, the opposite or head end of the sleeve 26 is also provided with live steam at all-times when the throttle is open. The piston valve 27 is shown as connected by means of a spider to its operating rod 28 and it uncovers the ports 26 at each end of its stroke, thereby delivering steam to the main valve chamber twice for each full cycle of movement.

The large central portion 30 of the main valve chamber is connected by the elliptical chamber 31 with the chamber 13 around the sleeve 25 of the auxiliary or cut-off valve as clearly seen in Figure 2. All of this space comprising the chambers 12, 13 and 31 has a volume of substantially one-third of the total piston displacement and will hereinafter be referred to as the receiver volume. Its shape is unimportant but its function is highly important and is to provide a rela- 50- tively larger mean effective pressure in the cylinder. Consider, for instance, the condition where the main valve is set to cut-off at two-thirds stroke and the cut-off valve is set for one-fourth stroke. After admission by the main valve the cylinder will be filled with steam up to twentyfive per cent stroke and all of the receiver volume will likewise be filled with steam. Upon cut-off by the cut-off valve a quantity of steam equivalent to one-fourth cylinder displacement plus onethird cylinder displacement plus cylinder clearance will be available for expansion up until cutoff by the main valve. Similar action will occur at all cut-offs by the main valve until the main valve has been advanced until its cut-off is equiv- 1 alent to that of the cut-off valve, when steam expands directly into the cylinder up to cut-off and pressure in the receiver remains practically constant. In this case it no longer functions except as a conduit for the delivery of steam to the main valve. By using this receiver volume, a cylinder larger than ordinarily used with various other limiting cut-off schemes is permissible, thereby realizing greater benefit from the expansive force of the high pressure steam, and

I seldom producing starting torque in excess of the adhesion between drivers and rail which is normally the limiting factor in cylinder size.

The rod 35 of the main valve is secured to a cross head 36 running in guides 37 clearly seen in Figures 2 and 4. Pivoted intermediate its end to this cross head 36 is the lap and lead lever 38, the lower end of which is connected by the link 39 to the pivot 10 on the main cross head 17. To the upper end of the lap and lead lever above its junction with the cross head 35 is pivoted one end of the radius rod 41, the opposite end of which is secured to a link block sliding in the slot 42 in the link 43 which is itself pivoted and driven by the eccentric rod 44 from the eccentric pin 45 carried by the driving pin 20'. The position of the block on the end of the radius rod can be adjusted in the slot 42 by the lift arm 46. The linkage just described constitutes the well known Walschaert valve gear as widely used on locomotives and serves to drive the main valve in proper timed relation to the piston movement and crank pin position and permits, by means of the adjustment of the lift arm 46, both reversal of the locomotive and adjustment of the main valve to vary the cut-off and conjugate events. It is preferably so designed and the valve so constructed that cut-off may occur from twenty-five per cent piston stroke to at least seventy-five or eighty per cent piston stroke which amount is necessary for starting under a heavy load,

The cut-off valve is so designed and driven that its nominal cut-off is fixed and preferably is about twenty-five per cent piston stroke. For this purpose the cut-off valve is driven directly from the main cross head 17. This is effected by having the rod 28 of the cut-off valve secured to a cross head operating in guides 51 and having the lever 52 pivoted at its upper end to this cross head. The lower end of the lever is connected by a link 53, identical with the link 39, to the pivot shaft 40 on the main cross head 17. A link or preferably a pair of links 55 is pivoted to the lever 52 at 56, a short distance below the cross head 50 and at its opposite end to a bracket 57. projecting from the casing supporting the valves. This valve mechanism drives the cut-off valve in proportionate conformity to the movement of the main piston and the valve is so dimensioned that nominal cut-off occurs at the desired point. say approximately twenty-five per cent piston stroke.

From the above, the operation of the locomotive will be evident. The cut-off valve is designed to open considerably. before admission by the main valve so asto fill the receiver volume and to ensure full pressure therein when the main valve opens. Upon admission by the main valve steam is delivered through the receiver volume and into the cylinder until C'lltvOfi is effected by the cut-off valve, after which steam, both in the cylinder and in the receiver volume, will expand until steam is cut-off by the main valve, after which further expansion will take place in the cylinder only until release is effected by the main valve. It is preferred to operate with the main valve adjusted for a fairly large cut-01f even at rather high speeds to prevent excessive compression, so that the real cut-off is effected by the cut-off valve and full advantage is taken of the expansion in the receiver volume. The. addition of the few parts comprising the auxiliary valve and its operating mechanism enables the steam engine of variable speed to be operated more economically and with better valve performance. The use of the type of cut-off valve just described in combination with the restricted port opening controlled thereby which causes wire drawing of the steam, permits earlier virtual cutoff than is possible with a conventional form or" single valve controlled by the usual linkage and.

through the cylinder ports without harmful effect on the release and compression, which are governed solely by the main valve.

Since, when operating at high speeds, itis desired to havea cut-off of about ten per cent for economical operation the total area of the ports 26, controlled by the cut-off valve, is such as to provide a throttling effect so that although the nominal cut-off of the valve is always that for which it is initially set or built, the total amount of steam delivered at high speeds will correspond to approximately that which could be delivered at ten per cent cut-off without throttling. This can be determined by suitable indicator cards and is a very important feature of the present invention for it provides automatic control of the cut-off with a reduction proportional to the speed of the locomotive without the introduction of any additional mechanism.

In order that cut-offs up to the maximum for which the main valve can be set shall be available for starting and operation at very slow speed under heavy loads a cross pipe 60, shown in Figure 2, connects the receiver volumes of the two engines of the locomotive. It is customary that these engines be set with their cranks displaced ninety degrees so that when one piston is at the end of its stroke the other is at the halfway point. The cut-off valve opens early and prior to admission by the main valve so it is open prior to cut-01f by the cut-off valve in the opposite cylinder. Thus steam is delivered through the cross pipe 60 after cut-off by the cutoff valve of one cylinder due to early admission by the cut-off valve of the other cylinder and steam is thus available up to the full cutoff of the main valve by reason of this cross pipe. A reverse flow will be effected upon operation of the opposite cylinder. Under these conditions there will, of course, be live steam pressure on the operating face of each piston until cut-ofi by the main valve. The pipe 60 is of restricted cross sectional area so that the amount of steam flowing through it is effective only when the pistons are moving very slowly or when starting. As soon, however, as a reasonable speed is attained the friction in this pipe is such as to restrict the quantity of steam flowing therethrough in the short time allowed so that the quantity is insuincient to materially affect the operation of either engine. This provides automatic delivery of steam for starting without manipulation of the amiliary cut-off valves and also provides automatic reduction in the quantity as the engine speed increases without additional mechanism or moving parts.

The locomotive may be said to be provided with automatic means inherent in the cut-off valve to reduce the virtual cut-off as the speed increases and automatic means to reduce the amount of steam delivered from one engine to the other for starting purpose as the engine speed increases, both without the use of any moving parts or adjusting devices.

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

1. In a steam engine, in combination, a cylinder, a piston reciprocable therein, a slide Valve controlling live and exhaust steam for said cylinder, a cut-off valve between said slide valve and the source of live steam, means to operate the slide valve and adjustable to change the timing of the events controlled thereby, means to drive said cut-off valve to provide a fixed cut-off thereby less than that required for starting, a port controlled by said cut-oh valve, said port being of such size as to so throttle the steam passing to the cylinder at high engine speeds as to produce the effect of materially earlier cut-off than thevalve is set for.- 1

2. In a steamengine, in combination, a cylindelja piston reciprocable therein, a slide valve controlling live and exhaust steam for said cylinder, operating means for said valve adjustable to change the timing of the events controlled thereby, a cut-oil? valve between said slide valve and the source of live steam, means to drive said cut-cit valve toprovide a fixed cut-on thereby greater than that required at high speeds and less than that required for starting, and means inherent to the cut-off valve to reduce the effective cut-off thereby at high speed to that most efficient.

3. In a steam engine, in combination, a cylinder, a piston reciprocable therein, a slide valve controlling live and exhaust steam for said cylinder, a cut-off valve between said slide valve and the source of live steam, means to operate the slide valve and adjustable to change the timing of the events controlled thereby, means to drive said cut-oil valve to provide a fixed cut-ofi thereby less than that required for starting, a port controlled by said cut-off valve, said port being of such size as to throttle the steam passing to the cylinder at high engine speeds and produce the effect of earlier cut-off than that for which the valve is set.

4. In a steam engine, in combination, a cylinder, a piston reciprocable therein, a main slide valve controlling live and exhaust steam for said cylinder, operating means for said valve adjustable to change the timing of the events controlled thereby, a cut-off valve between said slide valve and the source of live steam, means to drive said cut-off valve to provide a fixed cut-off thereby greater than that required at high speeds and less than that required for starting, a receiver volume between said valves, the timing of said cut-off valve providing admission to the receiver volume in advance of admission by the main valve, and means whereby said cut-off valve throttles the incoming steam at highspeeds to deliver a reduced quantity of steam to said receiver volume after mam valve admission to provide the efiect of an earlier cut-off than that for which the cut-off valve is set.

5. In an engine having a plurality of main cylinders, each with a main valve which, in full gear, cuts oii steam after the piston has completed at least two-thirds of its stroke, the combination of a cut-on valve for each cylinder, means to drive the cut-off valves with a fixed cut-01f at substantially one-quarter piston stroke, a receiver volume for each cylinder intermediate its valves, 1

quantity passing the cut-off valves as the engine speed increases.

6. In a steam engine, in combination, a cylinder, a piston operable therein, a main valve controlling admission, cut-ofi, release and compression points, means to adjust the valve to vary said points, a cut-off valve, means to drive said cut-oil valve synchronously with the piston with a fixed cut-off of about twentyfive per cent and means inherent to the cut-oil" valve to reduce the flow therethrough at high speeds to the equivalent of substantially ten per cent cut-off.

'7. In a locomotive, in combination, a cylinder, a piston operable therein, a main valve to control live and exhaust steam to said cylinder, a cut-off valve having fixed nominal cut-off of substantially twenty-five per cent and driven synchronously with said piston, a receiver volume between said valves of substantially one-third cylinder volume, means to adjust said main valve from cut-01f by the cut-oil valve to at least sixtysix per cent and means to automatically reduce the volume of steam passed by the cut-off valve to substantially the equivalent of ten per cent cut-oil at high speeds.

8. In a steam engine, in combination, a cyli'rider, a piston therein, a main valve chamber, a piston valve therein of the inside admission type and adapted to control admission release and compression, a steam supply pipe, a cut-off valve chamber between said pipe and main'valve chamber, a valve in said cut-oii? valve chamber adapted to control cut-oiT to the cylinder, a receiver volume of at least 20% of the piston displacement forming the steam connection between said valve chambers, said receiver volume including a central enlargement of the main valve chamber and a portion surrounding the cut-off valve chamher.

9. In alocomotive, in combination, a cylinder, a piston operable therein, a main valve of the inside admissiontype, adjustable radial-type operating gear for said main valve, a receiver volume ahead of said main valve, an independent cut-oil valve of a fixed cut-01f having a single port discharging into the receiver volume, and single means to drive said cut-on valve directly from and in synchronism with the piston.

WILLIAM F. KIESEL, JR;

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