US252084A - Direct-acting engine - Google Patents

Description

' No Model.) 2 Sheets-Sheet '1.

-- G. E. DOW.

DIRECT ACTING ENGINE. No.. 252,084. Patented Jan. 10,1882.

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; vuyrexl,"110W. DIRECT ACTING-ENGINE. No.. 252,084. Patented Jan. 10,1882.

V i Z UNITED STATES PATENT OFFICE.

GEORGE E. DOW, OF SAN FRANCISCO, CALIFORNIA.

DIRECT-ACTING ENGINE.

SPECIFICATION forming part of LettersPatent No. 252,084, dated January 10, 1882. Application filed August 6, 1881. (N 0 model.)

To all whom it may concern Be it known that I, GEORGE E. Dow, of the city and county of San Francisco, State of California, have invented an Improved Direct-Acting Engine; and I do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to certain improvements in direct-acting. steam-engines; and it consists in a novel combination of main and auxiliary valves and ports and the supplemeir tal piston, so that both valves are driven by the direct motion of the auxiliary piston. The

necessary amount of lead is given to the aux-.

iliary valve by makin gthe main valve somewhat shorter than the recess in the piston in which the valves lie and by which they are driven. By this arrangement I am able to better control the movements of the engine, particularly at the point of reversing, as the main valve has at that time moved gradually to the center of its travel or lapped position, thus automaticallyclosing its ports, both induction and eduction. This admits of working the main steampiston very closely to the cylindenheads with safety, as the slightest acquired momentum of the piston and its connected reciprocating parts reverses the main and auxiliary valves immediately after reaching the normal point for change of stroke. The effect of this is to give a live-"steam cushion and release from the acta ing side-of the piston without the great clearance-space employed in other engines operated by steam-moved valves.

Referring to the accompanying drawings for a more complete explanation of my invention, Figure l is a longitudinal section of the main and auxiliary cylinders, taken through the auxiliary valve and its ports. Fig. 2 is a top view of the valve-seat. Fig. 3 is a transverse section of cylinder and valves. Fig. 4 is an enlarged section of the valve'chamber, taken through the supplemental valve. A is the main cylinder, within which the piston B reciprocates. O is the piston-rod. D is the supplemental cylinder. E is the piston, having a depression or recess, F, on the lower side, into which the valves tit, so as to bemoved by the supplemental piston. Any mechanism may beemployed for operating these valves that will give a positive connection with the main piston or rod to impart motion in the proper direction and admit of the valves com pleting the latter half of the stroke by steampressure independent of the movement of the main piston. In the present case I have shown a device described in Patent No. 221,220.

The main valve G and the auxiliary valve H maybe side by side upon the same seat, and both valves fit into the recess F iuthe sup; plemental piston, as shown in Fig. 3; but the principle here shown may be accomplished by other forms of construction. The main steamports I I are controlled by the main valve and open into the ends of the main cylindenJin the main exhaust-port.

K K are the auxiliary steam-ports opening into the ends of the supplemental cylinder, and the exhaust discharges into the main ex ha-ust J, these being all controlled by the auxiliary valve H, as shown.

The operation will then be as follows: With the steampiston B moving in the direction of the arrow, and motion being imparted to the valve-stem by means of a suitable connection with the piston-rod, as shown, the valve-driving piston E will move the auxiliary slide-valve H and main valveG. The latter has alost motion longitudinally in the recess of said piston for the purpose of allowing sufficient lead to the auxiliary valve, which is always coincident with valve piston and rod. Hence the advance of the main piston moves both the main and auxiliary valves to gradually close the ports I and K, and as the main valve is necessarily behind in closing its ports to the main steamcylinder the auxiliary valve is allowed to pass somewhat the center of'its travel, alternating the pressure upon the supplementary piston, through the ports K and K, to drive the valves ,to the end of the travel, just before the main valve covers its ports to arrest the movement of the main piston. This prevents dead-points at the slowest speed, and at all speeds, the interval between reversing the auxiliary and the main valve being so limited, the main piston is cushioned very close to the cylinder-heads. The ports K and K are so located in the supplementary cylinder-chambers as to offer suflicient cushion to prevent striking the heads. :00

It will be noticed that all the moving parts of this engine are mechanically connected, and no dependence is placed upon the use of steam to start the suplementary piston or main valve, steam being employed only to continue the motion of the same after the main piston has come to rest; and also that each movement of this engine must open the auxiliary ports K and K to their full capacity, thereby creating an action more positive than other steamvalve systems, when a pressure of water or other non-elastic fluid is applied, as in start ing, 800.

As a result of this combination I am able to construct an engine for driving pumps, &c., more simple in construction, taking less steam or compressed air, as alarger proportion of the power is utilized for useful effort, and but one-half the amount of steam is used to operate the valves as compared with other steammoved valves-thatis, my engine movesits own valves about one-half their travel, and steam is expended only to complete the stroke. The complete action of the auxiliary valve, always carried at full stroke with the valve-driving piston, enables this engine to run equally as well with water-pressure as with steam or compressed air.

I am aware that an auxiliary piston carrying the main valve working in a slotin the pistonrod, and carrying also an auxiliary valve, (in such manner that, in the reciprocation-0f the valves, the main valve is allowed to fall be- In Witness whereof I have hereunto set my hand.

' GEORGE E. DOW.

Witnesses:

GEO. H. STRONG, FRANK A. BRooKs.

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