US1261925A - Valve-gear for reciprocating steam-engines. - Google Patents

Description

H. C. GRAY.

VALVE GEAR FOR RECIPROCATING STEAM ENGINES.

APPLICATION man AUG-2|. I916:

Pa tented Apr. 9, 1918.

4 SHEETS-SHEET l- WITNESSES: IN l/EN TOR ATTORNEY H. C. GRAY.

VALVE GEAR FOR REGIPROCATING STEAM ENGINES.

7 .APPLICATION FILED AUG-2|, I916- 1,261,925. Patented Apr. 9-, 1918.

4 SHEETS-SHEET 2.

6'7 v a I I H v I I A/d v ///V/?) 6, 5/341. WITNESSES INVENTOR.

I R E Y H. c. GRAY. VALVE GEAR FOR RECIPROCATING STEAM ENGINES.

APPLICATION FILED AUG-2|, 1916- 1,261,925. Patented .9, 1918.

4 SHEET EEI 3.

1 W mow-EM H. C. GRAY.

- VALVE GEAR FOR RECIPROCATING STEAM ENGINES.

APPLICATION FILED AUG-2h 1916.

1,261,925. V PatehtedApr. 9,1918.

HIFII WITNESSES: 0

ATTORNEY ran srarns PATN rionf HENRY'C. GRAY, or LOUISVILLE, KENTUCKY.

I VALVE-GEAR FOR RECIPROCATING STEAM-ENGIN ES.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Application filed August 21, 1916. Serial No. 116,023.

To all whom z'tmay concern:

Be is known that I, HENRY C(GRAY, of

Louisville, Jefferson county, Kentucky, have invented new and useful improvements in Valve-Gears for Reciprocating Steam-Engines.

My invention relates to improvements in that type of valve gear known as the Walschaert valve gear, wherein the movement of the valve is eifected'both from the driving wheel and from the piston-rod. 1n the VValschaert type of valve gear, the motion of the piston rod, through intermediate -means, modifies the motion derived from the driving shaft, so as to produce what is known as lead. 'The meaning of this term will appear later. The lead produced by the Walschaert valve gear remains constant, whether steam is. being admitted for the full stroke of'the piston, or a fractional part thereof. This want of variation is a disadvantage, and one of the objects of the present invention isso to modifythe Walschaert-valvegear, that the leadiwill vary,

the variation. being dependent upon the point at which cut-01f is effected; that is,

so that a different, lead will be secured when steam is being admitted during the full length of the stroke than is secured when it is being cut oif, and so that the amount of lead will be variable according to the part of the stroke at which cutoff is effected. I k

The commonest application of this type of valve gear is to steam locomotives of the ordinary type, having cylinders in which pistons reciprocate, piston rods attached to the pistons, and driving wheels revolving on shafts or axles, valves by which steam 1s admitted to the cylinders, and by which it is cut-off, valve stems, and other features in common use on locomotives.

I attain the objects of my invention by the mechanism illustrated in the accompanying drawings in which- Figure 1 is a side view of the mechanism showing the cylinder and the valve chest in cross-section.

Fig. 2 is an end View of the hanger at X X, showing theguides and valve stem in cross-section.

Fig. is a side view of the apparatus, which, llke Fig. 1, shows the cylinder and Unlike Fig. 1 it steam chest in section. shows the steam chest and cylinder broken off at the front end, and shows the link, later described, with the link bracket piece removed. Fig. 3 also differs from Fig. 1 in that it represents the piston at half stroke, instead of showing the crank on dead center, and also shows the link block.

Both in Fig. l and Fig. 3, for simplicity and compactness, certain parts are shown as broken.

Fig. d is an enlarged view of the detail adjacent to the point where the combination lever and the radius rod (later referred to) are connected, with the guide pieces partially cut away so as to show certain parts they would hide. i

Fig. 5 is a side view of the guide blocks later referred to, and Fig. 6 an end view thereof.

Fig. 7 is a top view of the valve-stem-crosshead-driving-block, Fig. 8 an end view of the top portion of the same, Fig. 9 a side view of the top portion of same, F igz lO a side view of the bottom portion of same, and Fig. 11 a plan of the bottom portion of 3 same.

Fig. 12 is an end view of one of the slides, Fig. 13 a top vlew thereof, and Fig. 14 a side view thereof.

. the eccentric crank A and at B to the foot, 13*, of the link 13, which is pivoted at the trunnion B; B is the link bracket piece, which does not appear in Fig. 3, this part of the link structure having been removed so as to show the block B which is adaptcross head driving- J[ as 20 11 be 8 on bereasu 0ss and any motlon vement in cam wi 0m ihi 1n some 130 a0n-rod reduces 011 shown pis amount 1. (L .L u

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:1 s1 pied at 11d iih shes there he Ste? lift rod

will beequal to that component of the 1110- tion of said point in the combination lever, which is parallel to the axis of the valvestem. If the valve stem had been attached to the end of the radius rod, and the block occupied theposition which it occupies in Fig. 1, it is evident that the lead shown at C would be difi'erent or would not exist at all, the said leadlbeing due, as an examination of the drawing will show, to the inclination of the combination lever; that is, in

- the l Valschaert type of valve gear, dependence for the necessary lead is placed on the chine is put together,

combination lever to which the valve stem is attached. In the ordinary type of Walschaert valve gear, the motion of the valve piston and valve stem is governed by some one point of the combination lever to which it is attached, andthe resulting lead, after the apparatus is once adjusted, does not vary at all. No matter what the position ofthe block B is; no matter whether steam is admitted during the full length of the stroke or cut off at some intermediate point, the lead will be the same. The amount of the lead will, of course, vary with the ratio which exists between two distances, to wit, the distance from the center of the pivot B where the combination lever is connected with the link B and the center or the pivotal connection between the combination ever 13 and radius rod B on the one hand,

and on the other hand the distance measured along the combination lever from the center of said pivot C between radius rod and combinationlever and the point in the coinhination lever which controls-the motion of the valve stem C In the ordinary, ll alschaert type of valve ear, these two distances are fixed and invariable after the ma- In the applicants device, this ratio is made variable, as will be seen, through the slide structure, which is adapted to slide alongthe combinationlever and more with sar ie so that a change occur ring in th position of this slide structure brings it about that the motion of the valve stem correspondsto a new point in the cone bination lever, and produces "a change in the ratio ofthe two distances before described.

In applicants device, further, the shitting along the combination lever) of the slide structure from which the valve stem is actuated, is produced by the rising or falling of the s! or falling ofwhichis brought about through the operation of the reversing lever B which is also the agency by which the cut-oil of steam is regulated. Therefore applicants device furnishes 'a means by which one JDQIKlEtl controlling bar 3, the rising motion of the reach rod will at the same time produce a change as to the admission of steam intothe cylinder, and a change in the amoimt oflead which is provided for.

With reference to the manner in which the raising or lowering of the suspended controlling bar B actuates the sliding, structure which'controls the motion of the valve stem and the point/in the combination lever whose motion controls the motion of the valve stem, reference to Fig. a will show that :1 raising of the suspended controlling bar B, which slides in the valve stem-cross-headdrivingblock C raises the pin C and slides C, which will move in the slot C in the side wings of the cross-head C" so that the motion of the combination lever, being commnnicated to the slide C, will operate against the sides of the slot C at a higher point than before and therefore at a point which is closer to the pivot point between the radius rod and combination lever.

In the form of apparatus shown, the adjustment is such that when the block B is at either extremity of the slot the motion of the radius rodvhas a maximum travel, and steam will be admitted to the cylinder through the entire stroke; when the block is in either of these positions, the suspended controlling bar is at its highest. This being true, the point in the combination lever whose motion determines the motion of the valve stem is closer to the pivot pin C than it willever get otherwise. Therefore, when the block is in either of these extreme positions the lead will be least. is theblock is moved toward the pivot of the link, the

limits of travelof the valve piston C diminish, and the steam is cut oil before the stroke is hmshed. It'is evident that as the block 18 moved toward the pivot of the link, the

controlling bar :8 will descend, until the lead will be maximum at mid position.

The principal utility of lead in steam engines consists first in the fact that it provides a cushioningretlect against battering by reciprocating parts at extreme positions, the steam admitted in advance serving to soften the thrust of the piston; and secondly, in securing a large steam opening during the period when the piston requires more steam; that is, at the early portion of its strol-ze, thus giving steam in the cylinder direction of the axis of the valve stem, will 3. In a. valve gear for reciprocating steam engines having a piston, principal shaft, and

a valve having stationary and movable parts,

the combina tion of a radius rod, a combination lever pivotally connected therewith, means for driving sa-idradius rod and regulating the limits of travel of saidradius rod, means for communicating motion and force from the piston to the combination lever, said combination lever being forked near the point at which it is pivoted to the radius rod, slides, a rod connecting the same, a valve stem fixed to the movable part of the valve, a valve stem cross head fixed to said valve stem and having slots in which the connections of said slides are adapted to move.

4:- In a valve gear for reciprocating steam engines having a piston, principal shaft, and a valve having stationary and'movable parts, the combination of a radius rod, a combination lever, pivotally connected therewith, means for driving said radius rod and regulating the limits of travel of said radius rod, means for communicating motion and force from the piston to the combination lever, a valve-stemcross-head, movable parts, sliclable on the combination lever and adapted to actuate the valve stem crosshead, a controlling bar so formed and placed as to engage said slidable movable part, and determine the position thereof; said shift rod being connected with the means of driving and regulating the radius rod.

5. In a valve gear for reciprocating steam engines having a piston, principal shaft, and a valve having stationary and movable parts, the combination of a radius rod, a combination lever pivotally connected there with, means for driving said radius rod and regulating the limits of travel of said radius rod. means for communicating motion and force from the piston to the combination lever, a slide structure adapted to move with the combination lever and slide thereon, a valve stem fixed to the movable part of the valve, a valve stem cross head fixed to the valve stem, said cross head having a slot of such position. and dimensions that as the slide structure slides along the combination lever, a portion of the slide structure will slide in said slot, and so that any movement of the slide structure which has a compo nent in the direction of the axis of the valve stem, will cause a'motion of said cross head equal to said component and means for so actuating said slide structure that any change in the limits of travel in the radius rod will produce a change in the position of said slide structure withireference to the combination lever. V v

6. In a valve gear for reciprocating steam engines having a piston, principal shaft, and avalve having stationary and movable parts, the combination of a radius rod, a combination lever pivotally connected therewith, means for driving said radius rod and regulating the limits of travel of said radius rod, means for communicating motion and force from the piston to the combination lever, said combination lever being forked travel in the radius rod will produce a change in the position of said slide structure with reference to the combination lever. 7. In valve gear for reciprocating engines having pistons, principal shafts, valves and valve stems, an eccentric crank, a pivoted link, means for rocking said link as the eccentric crank revolves, a block slidable in said link, a radius rod pivotally connected with said block, a lifting arm, means for connecting said rod and lifting arm, a reversing arm,-a controlling bar shifting rod, said reversing arm being fixed to said lifting arm, and pivotally connected at one point with the reach rod, and at another with the controlling bar shifting rod, a suspended controlling bar pivotally connected with the shifting rod aforesaid, hangers supporting said suspended controlling bar, a combination lever, pivotally connected to the radius rod, means for actuating said combination lever from the motion of the piston rod, a structure slidable along the combination lever, means for connecting said structure with the valve stem so that any motion of same along the axis of the valve stem will be communicated to said valve stem, and means for causing said slidable structure to move along the combination lever according as the suspended controlling bar rises or falls.

8. In a valve gear for reciprocating steam engines,'having pistons and principal shafts, a radius rod, means for actuating same from the principal shaft, a pivoted link, a block movable therein, means for shifting the position of said block, means for connecting said block with the radius rod, means for moving the suspended controlling bar so as to vary its distance, within limits, from the radius rod, said means being connected and actuated so that the position of the controlling bar changes when the position of the block changes, a combination lever pivoted to theradius-rod, means for actuating said combination lever from the piston, means for actuating the valve stem so that its motion equals the displacement of some point in the combination lever so far as said dis?

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