US1643424A - System of control for marine engines - Google Patents

Description

Sept. 27, 1927. E. C. STAFFORD SYSTEM OF CONTROL FOR MARINE ENGINES Filed Deo. 19, 1924 wvanf Far] Stafford l Stratum! Patented Sept. 27, 192':

UNITED STATES 1,643,424 PATENT. oFFicE.-

EARL o. STAFFORD, 0E PHILADELPHIA,PENNSYLVANIA SYSTEM 0E coN'rnoL Eon MARINE ENGINES. i

l Application 'filed December 19, 1924. Serial No. 757,053.

My said invention rela-tes to a system of control intended primarily for marine engines of either the reciprocating or rotary types whereby the speed of the propeller shaft or shafts is limited to prevent racing. It is well-ltnown that in storinyfweather the piopellers of ships often are lifted out of the water whereupon their normal speed of about 100 R. P. M. tends to increase sud denly because of the removal of practically all resistance to rotation, such increase of speed causing damage to the ship in vari-1 ons Ways, which damage is sometimes very serious. By the use of the device of my 1nvention I` am able to cont-rol such racing within very close limits so that practically there is no marked increase in speed of rotation at anytime.

Another phase of the same difficulty arises when the propellers at their greatly increased speed strike the water again and meet with the normally great resistance offered the water, the sudden shock ofsuch resistance being very damaging to the engines and racking the ship badly. This also is prevented by thedevice of my invention.

Referring to the drawing the single figure shows a side elevation illustrating my in,-

vention.

In the drawing reference ycharacter 10 1ndicates the main steam pipe leading 'from the boilers by way of pipe 11 to themain throttle valve and the power converting parts of the engine hereinafter designated` forcenvenience as the engine. Betweenthe pipes 10 and 11 a valve casing 12 is interposed said casing containing a pair 'of v alves 13 controlling the passages leading from the pipe 1()r to the pipe 1l the whole forming a balanced valve. The valves 13 are fixed on a stem 14 and operate as one. The stem 14 has a hand wheel 15 thereon fixed to. an externally threaded .sleeve 16 mounted on the stem between a pair of iixed .collars 17.` An adjusting nut 18 is mounted on the screw provided by thethreaded sleeve 16 anda lever 19 is pivoted at 20 .on the nut `1.8 said lever also being pivoted at 2O to a link 21 having a fixed pivot at 22..

At its opposite end the lever. has pivoted thereto a connecting rod 23 pivoted at its other end to a piston 24 mounted to reciprocate in a cylinder 25 iixedly secured to the valve casing. A weight 26 on the lever tends to force the piston down to the lower end of the cylinder and it is normally held up in a position to open the valve byineans of coinpressed air entering through a pipe 27.

The pipe 27 is connected to the usual coinpressed air system of the ship by means of a pipe 28 controlled by a. needle valve 29. A pipe 30 leads from the needle valve to a control valve in a casing 31 said valve coniprising a block having seats at 32 and 33. A single stem 34 has oppositely directed conical faces providing valves for engaging the the respective conical seats 32 and33. In ther position illustrated in the drawing air can pass through the pipe 30, a small port 35, another port 3G, a pipe 37, the wall of a casing-38 and the pipe 27 to the cylinder 25.v

When the stem 34 is moved to its lower position the air pressure escapes from the cyl* inder 25 through the pipes 27 and 37 and the passage 36 to the valve vchamber and then out by way of branch passages 39 and the arrangementof parts is such lthat the pressurein the cylinder 25 becomes exhausted to such an extent as to permit the piston to fall to the bottom of the cylinder almost instantly upon reversal of the position of the valve in casing 31. l L n The controlling means for the valve stein 34 includes a lever 40 pivoted at 41'upon which the stein is supported by means of an adjusting nut 42 threaded en the stem. The lever has a V-shaped downward projection or cani at its free end resting on a similarly shaped cam 43 on a roclcshaft 44 and the roclzshaft 44 .carries a rockarm 45 with an enlarged rounded head engaging a slot near the upper end of the'cylinder 46 of plung-r er forming part ofwhat is in eifect a hydraulic ram'having a cylinder 47. A'stop pin 48 ycarried by .a float 48 limits the downward movement of the roclarin 45 in accordance with the level of the liquid in the casing. A pair of pumps are located in the casing, said pumps being connected to a rocksliaft 49 by means of connecting rods 50 pivoted at 51l to the respective pump plungei's 52., only one of which is shown in the drawing. The pl-unger 52 operates in a cyl# inder 53 and the two pumps act to force oil or other liquid into a common pipe 54.

The pipe 54 leads to the lower end of the cylinderI 47 and fluid `entering; this cylinder passes out by way of pipes 55 and 56 connected to a head 57 in which is a by-pass valve 57 which isadjustable to' control the amount of liquid passing throu-gh the pipes which together with the head constitute a upon the liquid will escape but will hold the piston at the height indicated until the Vaction of the pumps slows down sufficiently so that less liquid is forced into the cylinder 47 than can pass out through the by-pass whereupon the piston will again fall to the position `indicated in the drawing.

When the piston is elevated as has been described it raises the spherical end of the rockarm and removes the cam43 from underneath the lever 40 .thus permitting the valve stem 42 to fall andlclose the upper valve controlling the entrance for air while opening the lower or discharge valve. This closes the passage from the air system of the ship to the cylinder `25 and opens the passage from said cylinder to the outer air by way of the ports 89. Thereupon the piston 24 falls carrying with it the valve stem 14 and connected parts to close the main steam valve in the passage leading to the engine. y

`The action of the pumps depends on the operation of the rockshaft 49 which aswill be obvious is provided with separate cranks for` the two connecting rods 50 and this rocksh'aft isV oscillated bya rockarm or lever Y fixed at one end to the rockshaft and at the other end to some oscillating or rotating or reciprocating part of the engine. Thus it will be seen that when the ship pitches so as to lift the propeller out of the water and permit it to race, the speeding up of the engine will increase, the action of the pumps gwpand-thereby shutoff; the compressed air from the cylinder 25 and permit the main steam valve to close either wholly or in part. When the propeller `again strikes the water its actionwill be retarded andwill slow down the speed of the engine whereupon the action of the pump [will be belownormal and this will permit the piston 46 to fall moving the lever 40 and the valve stem 34 to close the outlet'ports 39 for compressed air and to reopen the passage from the source of compressed air to the cylinder 25V whereupon the piston 24 will be raised to open the main valve 13 and permit steam again to pass to the engine in full volume.

` The needle valve 29 has an important Y function in regulating the action of the com` pressed air in correspondence withthe wave action. 1f this takes the form of long rolling swells causing the ship to pitch slowlyV or, in the case of the larger ships, merely causing the propellers to be alternately submerged and partly uncovered without pitching, then the valve should be nearly closed so `that the air will be admitted relatively slowly; but if the sea is high and the troughs will be set for a certain normal R. P. M. of

the propeller shaft; e. g., R. P. M., by adjustment of the by-pass `valve and the hand-wheel of the main; valve, `the by-pass valve controlling the flow of fluid as above explained and the main valve 13 controlling the admission of steam between the pointfof minimum steam to keep the engine turning over up to the maximum of full steam production of the boiler. The control valve 34 is not stationary at normal speed but trembles or vibrates between the extremes of its short stroke,vwhich `is only about inch long. Whenever it stays at one end of the stroke even for a fewA strokesonly of the engine (if it is a. reciprocating one) the l change in rate of air admission affects the pressure in cylinder 25 andA thev piston 24 ascends or descends accordingl whereupon the flow of steam is correspon and the engine accelerated bring it back to normal. t i

It will be obvious to those skilled in the art that various` changes may bev made in mfy devicev without departing from the spirit o the invention and therefore I do not limit myself to what is shown in thedrawings and described in the specification but onlyras indicated in the appended claims.y While this system is well adapted for use with ships engines it may also be used oninternal-combustion engines and steam engines, both stationary and movable and of various types, as will be readily understood.

Having thus fully described m said invention, whatI claim as new an desire to secure by LettersPatent, is: l

1. A system of control for marine engines including a steam pipe leading from the boiler to the engine, a valve in the pipe, means tending to close the valve including a gravity-operated piston, fluid-pressure means for restraining the action" of `the piston, a speed-responsive valve adapted when in one position topermit the flow of `pressure-fluid to said piston and when inanother position to permit fluid to exhausttherethrough from said piston,- and amanually-operated valve also controlling the flow of 'said fluid, substantially as'setforth. y

2. A system of control for marine engines comprising a main steam passage leading from the boiler to the engine, a valve in the passage, a weight tending to close said valve,

or deceler'ated to y a fluid-operated piston opposing the action ingly varied,

of the weight," a *control valve for the operatingfluid for said piston, means for actuating the control valve including a pump` operated by a moving element of the engine, and means for determining th-e normal speed of the engine including a liquid by-pass leading from said pump and a valve in said bypass, substantially as set forth.

3. The combination with a main steam supply passage, of a valve in said passage, a governor for said valve comprising pneumatic means for holding said valve in unseated position, a control valve for sai-d pneumatic means, and hydraulic means for operating said control valve to permit fluid to operate the valve` in the steam supply passage when the control valve is in one position and to permit the iuid to leak back through said control valve When the same is in another position, substantially as set forth.

4. The combination in a system for controlling marine engines, of a main steam passage, a control valve in said passage, pneumatic means for governing the control valve, a second control valve associated With said pneumatic means, a lever engaging said valve, a rocker arm for elevating and 'depressing said lever, and hydraulic means for controlling the height of said rock-er arm, substantially as set forth.

5. The combination in a system for controlling marine engines, of a main steam passage, a control valve in said passage, pneumatic means for governing the control valve, a second control valve associated With said pneumatic means, a lever engaging said valve, a rocker arm for elevating and depressing said lever, hydraulic means for controlling the height of said rocker arm, and a float for preventing the rocker arm from descending beyond a predetermined height, substantially as set forth.

6. The structure set forth in claim 5, and means for limiting the action of said hydraulic means, substantially as set forth.

In Witness whereof, I have hereunto set my hand at Washington, District of Columbia, this seventeenth day of December, A. D. nineteen hundred and twenty-four.

EARL C. STAFFORD.

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