US511836A

US511836A - John dahlstrom

Info

Publication number: US511836A
Authority: US
Publication date: 1894-01-02
Anticipated expiration: 1911-01-02

Description

(No Model.)

J. DA-HLSTRUM. VALVE GEAR FOR STEAM ENGINES.

Patented Jan. 2, 1894.

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JOHN DAHLSTRUM, OF BUFFALO, NEW YORK, ASSIGNOR OF ONF-FOURTII TO HARRY ll. BARCLAY, OF SAME PLACE.

VALVE-=GEAR FOR STEAM ENGlNES.

SPECIFICATION forming part of Letters Patent No. 51 1,836, dated January 2, 1894.

Application filed June 13,1893. Serial No 477,418. (No model.)

To all whom it may concern.-

Be it known that 1, JOHN DAnLs'rRon, a citizen of the United States, residing at Buffalo, in the county of Erie and State of New York, have invented new and useful Improvements in Valve-Gear for Steam-Engines, of which the following is a specification.

This invention relates to direct acting steam engines which are provided with a main 1o slide valve and an auxiliary slide valve connected with the main valve, such, for instance, as are used in steam pumps.

Qne object of my invention is to improve the construction of the valve mechanism by contriving it in such a manner that the auxiliary valve is actuated wholly by mechanical means, while the main valve is operated, during part of its stroke, by the auxiliary valve, and during the remainder of its stroke by steam pressure.

Another object of my invention is to improve the mechanical means whereby the auxiliary valve is operated.

In the accompanying drawings:-Figure 1 is a longitudinal sectional elevation of a direct-acting steam engine provided with my improvements and showing the piston at the end of its backward stroke and the main valve in its central position. Fig. 2 is a longitudinal section of the steam chest and valves, showing the main valve at the end of its forward stroke. Fig. 3 is a fragmentary longitudinal section of the steam chest and main valve, showing the latter in its foremost position, the section being taken on one side of the center for the purpose of showing the exhaust cavity in the main valve. Figs. 4

and 5 are vertical transverse sections in lines 4-4: and 5-5, Fig. 1, respectively. Fig. 6 is a bottom plan view of the main valve.

Like letters of reference refer to like parts in the several figures.

A represents the steam cylinder, B the piston and b the piston rod.

4 5 0 represents the cylindrical steam chest which is arranged parallel with the steam cylinder.

cl 07, represent the main frontand rear steam ports leading from opposite ends of the steam chest to opposite ends of the steam cylinders.

E is the exhaust chamber arranged on the under side of the steam chest and opening centrally into the under side thereof.

e 6 represent the main front and rear exhaust ports arranged between the main steam 5 5 ports and the exhaust chamber and extending from the steam chest to the steam cylinder.

F represents a hollow main slide valve which reciprocates in the steam chest, and which is composed of two pistons ff connected by a contracted neck f forming a main exhaust cavityf between said pistons.

G represents the steam chamber arranged above the steam chest and provided with main front and rear steam passages g g opening into the end portions of the steam chest, diametrically opposite the steam ports 01 d.

H represents the steam supply pipe connected with the steam chamber.

During the reciprocating movement of the main slide valve its exhaust cavity alternately connects the main front and rear exhaust ports with the exhaust chamber, and one of its pistons closes the main steam passage and port in one end of the steam chest thereby shutting off steam to the adjacent end of the steam cylinder, while the other piston opens the main steam passage and port in the other end of the steam chest, thereby admitting 8o steam to the opposite end of the steam cylinder, as shown in Fig. 2.

I represents an auxiliary slide valve, preferably of cylindrical form, arranged to reciprocate in the bore of the main slide valve. The main and auxiliary slide valves are ca pable of lengthwise movement upon each other, but this movement is limited by a transverse bolt 2' secured to the main slide valve and passing through a longitudinal slot 1; in the auxiliary slide valve. The auxiliary slide valve is actuated Wholly by mechanical means, while the main slide valve is actuated partly by mechanical means and partly by steam pressure.

jj' represent auxiliary front and rear steam ports which extend from the steam chamber into the steam chest on theinner sides of the steam passages g g, and It k are auxiliary front and rear steam passages formed in the upper portion of the main slide valve and extending from the periphery to the bore thereof. When the main slide valve is in its central position in the steam chest, as shown in Fig. 1, its pistons close the main steam passages and ports at both ends of the steam chamber and chest, and both its auxiliary steam passages 70 7a are in line with the auxiliary steam ports 3' j of the steam chamber. When the main slide valve is in this position and the auxiliary slide valve is at either end of its movement, one of the auxiliary steam passages in the main slide valve is closed and shuts oif steam to the adjacent end of the steam chest, while the other auxiliary steam passage is open and admits steam to that end of the steam chest, which causes the main slide valve to be shifted toward the opposite end of the steam chest, as represented in Fig. 2.

Z Z represent front and rear exhaust channels formed lengthwise in the bottom portion of the bore of the main slide valve and extending inwardly from both ends of the latter.

m m represent auxiliary front and rear exhaust ports formed in the lower portion of the main slide valve between the exhaust channels and the main exhaust cavity, and extending from the bore to the periphery of the main slide valve.

n n represent auxiliary front and rear exhaust cavities which are formed in the under side of the auxiliary slide valve and which alternately connect the front exhaust channel with the front auxiliary exhaust port, and the rear exhaust channel with the rear auxil iary exhaust port.

923 represents the Valve rod, secured to the front end of the auxiliary slide valve, and passing through the front head of the steam chest. The front end of this valve rod is guided on a standard N secured upon the main frame of the engine.

0 represents a transverse rock shaft which is journaled in bearings o 0 formed on the standard N underneath the valve rod and which is actuated by a depending rock arm P secured with its upper end to the rock shaft outside of the bearing 0 and with its lower end to a cross head 19 on the piston rod by a link p.

Q representsa rock finger which is mounted loosely with its lower end on the rock shaft on the inner side of the bearing 0' and which engages loosely with its upper end in an eye q formed on the Valve rod.

g g represent radial tappets formed on the rock finger on opposite sides of its pivot.

R represents a collar secured to the rock shaft between the rock finger and the bearing 0 and provided with radial tappets r r which are arranged on opposite sides of the rock shaft, and which are adapted to engage with the tappets of the rock finger for shifting the valve rod and the valves connected therewith. The tappets of the collar and rock finger are so disposed that when the tappets on one side of the rock shaft are in contact with each other, the tappets on the opposite side are separated by an intervening space. This space produces lost motion during the first portion of the forward and backward strokes of the piston rod and causes the valve rod to be actuated only during the last portion of each stroke.

In the position of the parts represented in Fig. 1, the piston has completed its backward stroke and the main valve occupies its central position, thereby closing the main steam and exhaust ports and cutting off communication with both ends of the steam cylinder. In this position of the parts the rear tappet r of the rock shaft bears against the rear tappet g of the rock finger, and the auxiliary valve has been moved forwardly,.ther.eby

clearing the rear auxiliary steam passage of the main valve K and admitting steam into the rear end of the steam chest. The steam now enters the rear end of the steam chest and drives the main valve forwardly into the position shown in Fig. 2, thereby clearing the rear main steam passage and port and admitting steam to the rear end of the steam cylinder. This causes the main piston to move forwardly and the piston rod of the same to carry the rock arm forward. At the same time that the main valve clears the rear main steam passage and port its exhaust cavity connects the front main exhaust port with the exhaust chamber, as most clearly shown in Fig. 3. During the first portion of the forward movement of the main valve, when it is actuated by steam pressure, its front auxiliary exhaust port m opens into the front main exhaust port e of the steam cylinder and the front auxiliary exhaust cavity 71 of the auxiliary valve connects the front auxiliary exhaust port m with the front exhaust channel Z of the main valve, whereby the steam is permitted to exhaust from the front end of the steam chest into the exhaust chamber. During the last portion of the forward movement of the main valve communication between the front exhaust channel I and the front auxiliary exhaust cavity n is out off and the front auxiliary steam passage K clears the auxiliary valve and connects the front main steam passage 9 with the front end of the steam chest as represented in Fig. 2, thereby admitting steam into the front end of the steam chest whereby the main valve is cushioned at the end of its forward stroke and jarring or pounding is prevented. During the last portion of the forward movement of the main piston the front tappetr of the rock shaft engages with the front tappet q of the rock finger and moves the valve rod and the mainand auxiliary valvesconnectedtherewith backwardly. During the backward movement of the auxiliary valve the rear end of its slot bears against the transverse bolt of the main valve and carries the latter with it. At the end of the backward movement of the auxiliary valve the front auxiliary steam passage K arrives opposite the front auxiliary steam port j of the steam chamber, thereby admitting steam into the front end of the steam chest, whereby the main valve is driven by steam pressure to the end of its backward stroke. As the main valve clears the front main steam passage and port during the last portion of its backward movement steam is admitted into the front end of the steam cylinder, which causes the main piston to be moved backwardly and the main and auxiliary valves to be shifted forwardly into the position shown in Fig. 1. In this manner the auxiliary valve is positively operated from the piston rod and the main valve is positively operated from the auxiliary valve during the first part of its stroke and moved by steam pressure during the remainder of its stroke. This construction of the valves and their operating mechanism, is comparatively simple, as the valves have only a rectilinear and no oscillatory movement, and enables the valves to be produced at comparatively small cost and to be easily fitted and kept in working order.

I claim as my invention- 1. The combination with the steam cylinder, the piston, and the steam chest, ofa main slide valve arranged in said steam chest, an auxiliary valve arranged in the main slide valve, operated from the piston, and having a limited reciprocating motion with the main slide valve, whereby both valves are moved together until the movement of the auxiliary valve is arrested, when the stroke of the main Valve is completed by the action of the steam, substantially as set forth.

2. The combination with the steam cylinder, the piston and the steam chest, of a main valve arranged to slide in the steam chest and controlling the steam for actuating the piston, an auxiliary valve arranged to slide Within the main valve and provided with a slot, a transverse bolt or pin secured to the main valve and entering the slot of the auxiliary valve, the ends of said slot being arranged to come in contact with said pin or bolt during the first portion of the stroke of the auxiliary valve, and intermediate mechanism whereby the auxiliary valve is operated from the piston, substantially as set forth.

3. The combination with the steam cylinder, the piston and the steam chest connected with the cylinder by main steam and exhaust ports, of the steam chamber having main front and rear steam passages opening into the end portions of the chest, an exhaust chamber, a hollow main valve provided with a central exhaust cavity for connecting the exhaust ports with the exhaust chamber, and an auxiliary valve arranged to slide in the main valve and operated from the piston, substantially as set forth.

4. The combination with the steam cy1inder, the piston, the steam chest connected with the cylinder by main steam and exhaust ports, the steam chamber connected with the steam chest by main steam passages and auxiliary steam ports, and the exhaust chamber, of a hollow main valve provided centrally with a main exhaust cavity and having auxiliary steam passages extending from its outer side to its bore, and adapted to register with the auxiliary steam ports and the main steam passages of the steam chamber, and having longitudinal exhaust channels formed in its bore and auxiliary exhaust passages extending transversely from the bore to its outer side, and an auxiliary valve arranged to slide within the main valve and provided with auxiliary exhaust cavities adapted to connect the auxiliary exhaust passages with the exhaust channels, substantially as set forth.

5. The combination with the steam cylinder, the piston, the steam chest and the steam chamber, of a main slide valve arranged in said steam chest, an auxiliary slide valve arranged in the main slide valve, and capable of a limited longitudinal reciprocating motion with the main slide valve, and a rock finger connected with the auxiliary valve and actuated from the piston, whereby both valves are moved together until the movement of the auxiliary valve is arrested, when the main valve is moved farther and its stroke is completed by the action of the steam, substantially as set forth.

6. The combination with the steam cylinder, the piston, the piston rod, the steam chest, the valve and the valve rod, of a rock arm connected with the piston rod, and a rock finger connected with the valve rod and shifted by the rock arm during the last portion of the movement of the latter, substantially as set forth.

7. The combination with the steam cylinder, the piston, the piston rod, the steam chest, the valve and the valve rod, of a rock shaft, a rock finger mounted loosely on said shaft and connected with said valve rod, a rock arm secured to the rock shaft and connected with the piston rod, and tappets on the rock shaft adapted to engage with tappets on the rock finger, said tappets being so disposed that the rock finger is actuated during the last portion of the forward or backward stroke of the piston, substantially as set forth.

lVitness my hand this 10th day of June, 1893.

JOHN DAHLSTROM.

Witnesses:

THEO. L. POPP, F. (J. GEYER.