US1595740A - Operating mechanism for inlet valves - Google Patents

Description

Aug.10,1926; v 1,595,740

- J. STUMPF OPERATING MECHANISM FOR INLET VALVES Filed June 5, 1920 5 Sheets-Sheet 1 Aug. 10 1926.

Filed June 5. 1920 5 Sheets-Sheet 2 jkvemwrr Aug. 10 1926 J. STUMPF OPERATING MECHANISM FOR INLET VALVES Filed June 3', 1920 5 Sheets-Sheet 4 Aug. 10 1926.

I J- STUMPF OPERATING MECHANISM FOR INLET VALVES Filed June 5, 1920 5 Sheets-Shet s Patented Aug. 10, 1926.

UNITED srA JOHANN STUMPF,

or BERLIN, GERMANY.

, OPERATING MECHANISM FOR INLET VALVES.

Application filed. June-3,1920, Serial 110. 386,419, and in Germany December 18, 1914.

The invention relates to an inlet valve gear for steam engines,

a primary medium having high initial pressure and subsequent expansive force and 5 having a'two cycle operation. The ordinary valve gears have the draw-back that the opening of the valve does not in the least follow the piston speed. If the governor has, for instance, set the eccentric to give a cut-off from 8 to 10%, then an exceedingly small portion of the eccentric travel is active, giving extremely slow opening and closing of the valve and therefore excessive throttling of the steam, which condition naturally becomesworse for cut-offs smaller than 8fto 10%. Furthermore the idle motion is large. Eccentric andinlet valves have to be of large dimensions, which increases the difficulties for the governor to act properly;

The large valves bring about increasedleakage, large clearance volume andsurface. 7

According to the present invention,-the

existingvalve gears are to be improvedby making the lay-shaft angular speedrelative to the engine speed, as for example a multiple ofthe crank shaft angular speed.

In accorda-nce with the present invention means are provided to multiply the angle of thefeccentric circle active for the motion of the valve, which means a higher segment for this motion. With a lay-shaft angular speed forjexample of tWlCQ'tlIB crank shaft angular speed, it is possible to increase the valve lift about four times for a cut-off of 10%. Accordingly, a valve of substantially less diameter than that of the one used with the ordinary valve motion would be sufficient. Clearance space, clearance volume, weight of valve and leakage arereduced in an even higher .ratio and the lay-shaft governor would appear to be 'four times as powerful. v

Since the valve is to open but once for every engine turn, this new valve .motion makes the lay-shaft operative to" actuate the Valve once only foneach-revolution of the crank shaft t l 7 One method, for instance, in case the layshaft angular speed is twice the engine speed, is to arrange a second or auxiliary shaft preferably parallel to the lay-shaft and drive it at engine speed. This'shaft acts upon the mechanism connecting eccentrica nd valve in such 'a' 'mannervas to or engmes using make it-ineffective at every second revolution of the lay-shaft.

Or in some casesit would be advantageous to run the lay-shaft at engine speed, and the auxi iary shaft at twice engine speed.

Referring to the drawings, which illustrate merely by way of example, suitable means 'for the embodiment of my invention 7 I 1 Fig. 1 is a sectional view and partly diagrammaticshowing .an arrangement for effecting my invention, the valve in closed position. I c

Fig. 1 is a fragmentary detail on a reduced scale showing the position of the ele ments with the valve in the open position.

Fig. 1 is a similar view showing another position of .the elements with the valve closed. I Fig. 2 is a plan view in part section ofsame.

Figs. 3 to 8 inclusive, are diagrammatic views showing modifications.

. Fig. 9 is a partial front view of a modi-' fication. I

Fig. 10 is .a'plan .view"in part section showing same modification. 1

Fig. 11 is a diagr'anrillustrating the old and new valve motion. Fig. 12 is a plan view,on areduc'ed scale, of the engine showing the relation of the main or crank-shaft with the lay shaft I Similar reference letters refer to correspondingv partsfor elements throughout the several views. i Several diiferent arrangements of this valve gear arev shown in FigsQl to 10,; while Fig. 11 in a diagrammatic way illustrates the old and thefnew valve movement. In all the examples shown, the lay-shaft has twice the angular speedof the crank shaft. f The first arrangement, as shown in Figs. 1, 2, and 12, has a shaft 'overnor A mounted on the lay-shaft a which is driven at twice the angular speed cent to thislay-shaft is placed another, or auxiliary shaft 6, as shown in Fig. 2, driven from the lay-shaft by spur gears S with a ratio 1:2.

being shown of the crank shaft; Adja- The eccentric on shaft a has the equiva rod 0, to lever f, provided -withea roller on its free end for actuating the cam mecha trio on shaft a are approaching the nearest v movement which brings elements 6, 0 and a" point to lever f and that'e and 0 are in alinernent,- because of the relative position of the eccentric b; The completion of the inaline me'iit cansesthe actnation of lever f ed upon a second lever f I lever meter. the inlet valve. The short length of eccentric rod 0 further increases the valve lift with the same size eccentric and active angle.v Upon the next-complete revolution of shaft a, the shaft Z2 has only made a one-half revolution. The element or eccentric b will have reacheda point, as iii-Fig. 1 substanon y opposite that shown in Fig. 1. This will cause the movement of the point of con nection of c and c oiit of alinement so that at the end of this rotation of shaft a there will be no actuation of lever f. v Fig. 3 shows the bell crank lever f mountof similar shape which is pivoted on the valve bonnet. Eccentrio rod 0 acts immediately upon lever f while lever f is connected by means of rod to eccentric shaft ?2. The motion of lever f combines the motion of both shafts w and 6 according to the lever ratio with the result that also in this case the valve is opened one 'fer each revolution ofjshaft b. V

The arrangement shown in Fig. 4 has the eccentrics of shafts a and?) connected to f by means of rods 0 and and'a double lever g which ispi'veaa to arm 7 of lever .f.

dle of lever The only difl'erence between Fig. 4 and. F 5 is that in Fig. 5 the left end of double lever g is connected to ever 7 which is pivoted at f and rod f connec ts to the mid vFig. 6 shows the bell crank lever 7 carried on the single lever h. Eccentric rod 0 acts immediately iipon lever f. Lever it receives its motion from shaft 6 by means ofcain mechanism 2'. This cam is shaped in such a manner that during the periodth'e valve ismoved, pivot f of lever f remains staing wh ch receives its motion from tionary.

Fig. 7 shows the valve operated by'a walklever f resting against single lever is i shaft 6 by a mechanism similar. to the one employed in Fig.6. I Fig. 8 employs a c ammech'anismin which valve, actuated by the lay sha the governor acts upon lever 10 the lower end of which has linked to it lever w, which by means of eccentric rod 10 is connected 7 to shaft 6. Eccentric strap e of'eccentric e on shaft a is, by means of rod 0, linked to lever 10'. a J

The purpose of shaft 6 in this case is to bring eccentric strap .6, at every second revolution of lay-shaft a, into a position corresponding to zero cut ofi withoiit interfering with the action of the governor. V a

' igs. 9and 1O illustrate a partial front and plan View single eccentric shaft a, and under control of shaft governor A, oscillates shaft 7* by Ineansof arm 7". cam drum m and spur gear S are loose on shaft rebut secured against relative lateral motion 'with respect to shaft r. In mesh with spur gear Sf ratio being 122; Gear S The two inlet valves are operated by cams ooh-shaft 1'. This shaft is moved longitw dinally, the Cams 0 being or section respectively, ofa The mechanism for the longitudinal movement of shaft 1" consists of drum m having asuitable groove intowhieh projects a. fixed pmm.

g It is important to point out that this type of valvegear makespossible the "use of single' beat valves, which possess advantages over double beat valves.

Diagram Fig. 11 is illustrative of the operation in accordance with mji'inve'ntion and is based on eccentricjspeed-twiee the engine speed. The useful angle of the eccentric cir ole, normally a, is therebydon bled', as 2 and increases four the eccentric rod tan'ces 3 and 12. p r

If the lay shaft is arranged to run at double the engine speed,'-then the period of valve opening extends throiightwi'ce the an: gle a and the width of'the opening in creases fr'om to A, as shown in Fig. 11,

since as indicated b y the aiswhich belongs to a sector o-f'which' ais-half v the center angle;

What I claim is 7 w 1. In operating mechanism forengine inlet valves, the combination with the engine crank shaft of a lay shaft operating at-twice the number ofrevolutions as that of the crank shaft, and means for' opening the t, to increase the speed of the valve opening relatively to the crankshaft speed and thereby proporvalve gear. Eccentric e on is another gear S the; is keyedto shaft a.

7 placed in such manner that the valves are moved alternatelyi times the effective action of '3 i i therefore Az l" A, approximately within.

tionally increase the extent of valve opening ated by the lay shaft, to increase the speed Within a required period of each engine of the valve opening relatively to the crank cycle, and means associated therewith to preshaft speed and thereby proportionally inventthe valve from being opened more than crease the extent of valve'opening within a 5 once for each revolution of the crank shaft. required period of each engine cycle and 1 2. In operating mechanism for engine inmeans associated therewith to prevent the let valves, the combination With the engine valve from being opened more than once crank shaft of a lay shaft operating at a for each revolution of the crank shaft.

multiple of the revolutions of the crank U I 10 shaft, and means for opening the valve, actu- JOHANN STUMPF.

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