US395735A - Slide-valve - Google Patents

Description

(No Model.)

T. T. BROWN.

SLIDE VALVE.

Patented Jan. 8, 1889.

. fi W i? UNITED STATES PATENT OFFICE.

THOMAS T. :BROlVN, OF CHICAGO, ILLINOIS.

SLIDE-=VALVE.

SPECIFICATION forming part of Letters Patent No. 395,735, dated January 8, 18 89. Application filed March 21, 1888. Serial No. 267,942. (No model.)

To all whom it may concern:

Be it known that I, THOMAS T. BROWN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Slide-Valves, of which the following is a specification, to wit:

This invention relates to an improvement in slide-valves; and it consists in certain peculiarities of the construction and arrangement of the same, substantially as will be hereinafter more fully set forth and claimed.

To enable those skilled in the art to which my invention pertains to make and use the same, I will now proceed to describe its construction and operation, referring to the accompanying drawings, in which Figure l. is a longitudinal section of a steamcylinder with its valve, &c.; and Fig. 2 is a plan view of the same with the steam-cl'iest cover removed.

(4 represents a steam-cylinder, formed upon one side with a seat, a, for the usual slidevalve, and a? is the steam or valve chest. The seat a is centrally cored or chambered, as at b, for the main exhaust, and formed also with cored steam-passages 1), connecting with the ends of. the cylinder and acting alternately as supply and exhaust passages in the usual way.

The steam-piston c is moved back and forth in the usual manner by the admission of live steam behind it by the action of the slidevalve 0 in its travel back and forth upon its seat. This valve is formed with a cored exhaust-passage; 0 in. its face, which 'serves to connect the main exhaust passage 1') with either of the two passages b, accordingto the movement of the valve.

lVhen an engine is first started, it is common to give the valve its full stroke, so as to admit a full charge of live steam to aid in overcoming the inertia of the load; but after being fully started not so much power is required to retain a given speed, and in order to economize it is usual to shorten the valve stroke, so as to out off the live steam at a given point of stroke and utilize the expansion of the steam, as will be readily understood. This, however, often results in the opening of the supplyport and the admission of some steam behind the piston before the exhaust has been opened far enough to relieve the pressure upon the other side, and the result is a back-pressure, as the live steam upon one side must act against the expanded steam upon the other side till the travel of the valve has opened the exhaust sufficiently to give relief. This I avoid as follows: I form the valve 0 with a cored chamber, (Z, at each end, and each chamber is by a passage, d, connected with the face of the valve. In a cylindrical seat formed transversely through the upper part of the main valve is placed a rocking exhaust or auxiliary valve, (7 formed with a cored port, (7", in its face, and this transverse seat is by a pair of exhaust-ports, 6, connected with the main exhaust-passage c in the face of the main valve, and by two passages, c, with the chambers (I, as clearly shown in Fig. 1. An arm, f, upon one end of the auxiliary valve is passed loosely through a guide-sleeve, f, swiveled upon rod or stem, f passed out through the top of the steam-chest through a suitable stuliiug-box or similar means of keeping it steam-tight. This rod is operated by means of an angle-lever, g, fulcrumed on the outside of the chest, and provided with an operating-rod, g, which is led off to the engineers controlling-lever, and is operated by it at the same time the main valve is oper ated, as will be fully understood by reference to 1.

The operation will be obvious from the fore going description. Steam is admitted to the valve-chest, and from this to the cylinder at either end as the supply-ports are alternately uncovered by the sliding valve. In Fig. 1 I have shown the piston at the end of its stroke and just ready to commence its return movement. It will be noted that the main valve has just begun to admit live steam behind the piston, the supply-port being shown as partially open. At the same time the other passage, Z),which is now the exhaust, is connected by the cored face of the main valve with the main exhaust-port. This opening is, however, not sufficiently large to properly relieve the pressure of the expanded steam upon the face of the piston, and it will be seen that at the same time the auxiliary exhaust through the passage d, chamber (1, and the cored auxiliary 2 seems valve is in connection with the passage 5 and serves to give an additional vent to the exhaust and fully relieve all back-pressure till the onward movement of the main valx e has opened a sufficient area of the main exhaustpassage 0 to pass the necessary amount of steam,when the auxiliary passage closes, and it will be at once understood that this action is repeated at each stroke and in connection with each end of the cylinderalternately. It will also be noted that the reciprocating motion of the main valve carries the auxiliary one past the sliding stem or rod f and its guide-sleeve f, and the valve-arm f, sliding freely in the guide, rocks the auxiliary valve in proper time to open and close the auxiliary exhaust-passages, while the connection of the guide-sleeve to a movable rod operated from the starting-lever enables me to move or adjust the position of this guide at the same time and by the samem ovement as the adjustment of the main valve cut-off, and as the stroke of the main valve is reduced the stroke of the auxiliary one is enlarged to properly provide for an exhaust area of su'fficient size, no matter at what point the main valve is set to cut off for expansion. In a former patent granted to me I used this guide-sleeve swiveled upon a stud stationary on the inside of the steamchest; but in this form the shortening of the stroke of the main valve failed to carry the auxiliary one far enough past the stud to open a sufficient exhaust area, and I therefore make the location of the guide-sleeve adjustable and increase the roll of the auxiliary valvein direct proportion as the stroke of the main one is lessened, thus always preserving aperfect action, as will be at once understood by those skilled in this art.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

l. The combination, with a slide valve formed with a cored exhaust-passage in its face and a cored chamber on each side of the same connected by passages with the face of the valve, and also with its exhaust-passage,

of a cored rock-valve seated in the main valve across the auxiliary passages and a stem for operating this valve connected to an adjustable point upon the valve-chest, whereby the throw of the auxiliary valve is adjusted to suit the stroke of the main valve, substantiallyas and for the purpose set forth.

2. The combination, with a slide valve formed with suitable main and auxiliary exhaust-passages and a rock-valve seated in said auxiliary passages, of an operating-arm on this rock-valve and a guide for the arm swiveled upon a sliding rod past which the auxiliary valve is carried by the stroke of the main valve, and means, substantially as de- I scribed, for moving said rod to increase or diminish the throw of the auxiliary valve inversely to the adjustment of the main valve, substantially as and for the purpose setforth. In testimony whereof I a fiix my signature in presence of two witnesses.

THOMAS T. BROWVN. Vitnesses:

W. C. MOARTHUR, W. S. McARTHUR.

Images