US1809712A - Valve gear for steam engines - Google Patents

Description

June 9, 1931. F. A. KOWARICK VALVE GEAR FOR STEAM ENGINES Filed Jan. 9. 1929 2 Sheets-Sheet l June 9, 1931. ow R cK 1,809,712

VALVE'GEAR FOR STEAM ENGINES Filed Jan. 9; 1929 i 2 Sheets-Sheet 2 Patented Jun e 9, 1931:

rn-nnnnrco nn'ron xownmcmori sAorAoLo, imAzIn vanvneenenl non STEAM nnemn s Application filed lanuary. 9, 1 929 SeriaLNo.

The invention relates to; a valve gear for highspeed engines, working with superheated stea n,particularly multiple expansion engines, the piston of which reciprocates at a speed of 6 to 12 metres iIlltllB' second. Such a valve gear must answer the following ree quirements:

(1) Variable cut-oil.- within' wide. l mlts.

(2) A constant or a decreasinglead or "a a reduction of th'e'load at the discretion of the designer.

(3) Absolute zero admission. (4) Balance of cut-oil 'as well as of workns, and Q (5) Avoiding of every reaction on the regulator. 7

These requirements, are fulfilled by the valve. gear according to the present invention to, full extent. -This invention is characterized' the'i'act that the eccentric is made of two sections, namely an inner sec-' sired admission ranging .between absolute zero admission and eventually highest adm1ssion, even during the operation of the machine, and at the same time increasing or decreasing the lead corresponding to the degree of cut-off proportionally, or even to keep it constant.

tric sections a rotatable and ,sli'd'able adjusting member is arranged on the valve gear shaft bythe aid of a spiral guide. The adjusting member acts on the annular 's'ection of the eccentric by the aid of curvedpslot guides and on the inner section oftheccen tric by the aid of another spiral guide of.

dififerent inclination. f The eccentric strap y t ea drpfl em uid s en i' t th l t members of'the cylinder. These cam guides in Fig.2.

To enable an adjustment of the two men a 331,263, and in- Germany January 16, 1928.

aswell as the valve gear eccentricrun in a bath of oil'to guarantee-an easy run.

Fig. 1 of the drawingsis a sectionalele vation of a cylinder.

Fig. 2 is a cross section of. a sectional valve gear" eccentric taken on the line 1-1 of -te l a Q Fig. 3 is an end view of the eccentric shown FigA is an end view, an I Fig. 5 a side View of the inner eccentr c sectlon, and

Fig. 6 illustrates a spiral guideof'the valve I gear shaft carrying' the" adjustingmember; Figs. 7, 8, 9 and-1O are diagrams serving and the cam slots. a I V steani inlet and outletof the cylinder at having a pistont of'the machine shown in Fig, 1 is effected by the aid ofa slide for determ'ning the shape of the spiral guides valve 0. The slide valve rod n is operated by cams e which are operated in pairs by rods f wlthone another. By the aid of the eccentrio t straps h and links i the eccentrics g I mounted on the valve gear shafts Z: operate the rods The eccentrics g as well as the cams a run preferably in oil'baths not shown.

In the construction shown in. Figs. 2 to 6 the eccentric comprises an inner section having a circular circumference on which the section 'is adapted to rotate and which itself is rotatably ournaledton the valve gear shaft kQ The outer section 9? is surrounded by an eccentric strap k, the. circumference of the. outer section 9? being eccentric to the circumference-of the inner section 9. The

latter g is integral with the socket m, which is provided with a helical slot a. The annu-l lar section 9 is provided with two lateral projections, on which pins 0 are mounted. The valve gear shaft has a thickened part orflcollar 19, into. the cylindrical surface of which a helical slot 9 iscut. "A disk-'1' is provided with two opposite bosses s. ands,

which embrace the socket m and the collar.

p respectively. The bore of the boss sis provided with a helically shaped projection, which enters the helical'slot n on the socket m, and the bore of the boss .9" is provided with a helically shaped projection, which enters the helical slot 9 of the collar p. 011 the outer circun'iference of the boss 8 between two ball bearings t a ring it is held in position by two nuts 10 and provided with two arms 1%, which are connected with a fork u by screw bolts u. The fork in firmly pivoted and the outer end an may be connected with any known rodding not shown for reg ulating the cut-off.

When the rodding is operated the fork to transmits a longitudinal movement to the disk r on the collar p of the shaft 70. By the aid of the helical thread the disk 1" and simultaneously therewith the outer eccentric section g is rotated by the intermediary of the pins 0 and the slots 1" of the disk 1". .he amount of rotation depends on the previously 0 calculated inclination of the helical thread q and the longitudinal movement on the collar p.

At the same time with these movements the helical thread it causes a rotation of the socket m together with the inner eccentric section g in opposite direction, corresponding to the inclination of the helical thread n. Thus the rotation of g and-g enables different circles of stroke, which then effect by the cam c any desired admission at will and accordin to the construction. It is the task of the esigner by causing a rotation of the inner section 9' to the correct angle either to secure a constant or a variable lead, that is to say a proportionally reducing lead when the load of the machine is reduced, as well as when it is a question of heavy stationary machines to secure a balance of working, which eventually is to be found out.

In the Figs. 7 to 10 the manner of deciding the dimensions is explained. According to Fig. 7 first of all a minimum circle of stroke is to be chosen or calculated. This circle will be described as circle 1. Thereu on the larger circle of stroke 2 is drawn. T hese proportions g and wounded by these circles 1 and 2 represent the two eccentric sections. 0 is a center of the valve gear shaft and 0 a center of 9 Itis the condition that the center 0' is situated on the minimum circle 1 of the stroke. Now a line 3 is drawn at an angle of 30 to the horizontal tangent of the circle 1 at the point 0. The line 3 intersects the circle 2 at the point 4. By the aid of a pair of compasses the distance 0'4 is taken and by this a circular arc is described on the vertical. The center 0 of this circle will then be the found center for 9'. Not until now can the size of the eccentric be determined.

In the Fig. 8 g is taken to be fixed on the shaft, while 9 is rotated about 60. 1 is the outer diameter of g on the circumference of which 9 must move. lVhen now 7 is rotated from the point 2 to the point 3 the center 0 of 9 will move on the half circle 4 from 0 to 5*. When g is moved further up to 60 the center of 9 will be at the point 6, and the distance 0-45 is the radius of the largest circle of stroke. This circle of stroke will of course be larger when the rotation of g is continued.

If the hatched segment, shown in Fig. 8, is intended for a certain cut-oil and is retated alone for itself from the points 06 the different admissions will be understood. Thus the angle of lead, Fig. 8, with respect to 0% admission would vary up to the un known admission from 0% up to 30,since the crank shaft is firmly connected with the valve gear shaft.

To balance the difference of 30 in such manner that a correct opening is secured at any desired cut-off, 9' will be rotated in the opposite direction. This will be understood from Fig. 9, which for better illustration is drawn to a scale twice as large as that of Figs. 7 and 8. We proceed at first exactly in the same manner as in Fig. 8, all circles and lines are drawn, and also a segment for any desired cut-off. The line AB is thus the desired opening line for any cut-off, and now one has to try to practically approach the center of 9 this line. This is done in the following manner: If the largest cut-off is desired, 9 will be rotated for 60, so that its center 0' will be at .18. Now g must be so shifted, that the point 18 wanders towards A. The length 18A will be taken into the compasses and cut-off from the point 7 on the same circle of stroke, thus finding the point 8. Then now a straight line is drawn from 0 through 8 the angle of rotation for g is found at 14,4". When then the are 10 is drawn for the sake of checking that what is found, that is to say the path of the center of g, the compasses are set in at 9 and the circle 14 is drawn for g, and also when set in in A the circle 15 for g the correctness of the rotation will be recognized. The line A917 shows the new opening of 9 Thus the admission is correctly adjusted.

Now the eccentric sections 9 and g are proportionally moved by the helical guides, that is to say 15 for g and 3,6 for g. If new g is standing at an angle of 45 and g at an angle of 10,8 the center 9' will be at 11. The opening ofthe valve however cannot take place until at the point 13. Therefore the valve gear shaft and the crank shaft must rotate forwardly for the angle ,8 and the admission will take place later for this angle ,8. This is of advantage since for small fillings a slighter admission is desirable. However, even by other rotation of g a constant lead can be secured. In this case the center wanders on a straight line.

If the crank 1 is in the position shown in Fig. 9 the eccentrics in zero position of the crank must have a lead for an angle a. By rotation the openings must correspond to the fillings or admissions since the point 9 wanders towards A.

The Fig. 10 serves for determining the 1 helical slots 1' on the disk 1 for the entraining.

pins o of the eccentric section 9 thus for rotating the latter.

rotated about its center coinciding with the center of the valve gear shaft; The entrainspectively, while on the disk 9" they describe the curved paths 8 3 c3 ,13 and 44 4-4 14 respectively. The corresponding helical slots must be machined very carefully; The points 3 and 4 are the distances of the entraining pins 0 wit-hreference to the center of 9 I The drawing of the curved paths is efi'ected as follows: At first all the lines and circles are drawn as is done in Fig. 9. Ve have seen that the lineA9-17 is the new eccentric posit-ion corresponding to an angle of for and of 14,49 for g.- This line will now be drawn up in Fig. 10, thereupon a vertical line A through the point A and on this Vertical line the distances of the entraining pins 0 are cut-off, so that the points l3'and 14 are found. Now we go back for 15 for g'? and 3,6 for g respectively, anddraw the line 1 through 1-2 and the vertical 1 and designate the points 5' and 6.- In similar manner the line 7 the vertical'i the points 9 and 10 are drawn until all points are found. Thereby the curved path of the pins is given.

The same is to be done Withregardtothe curves on the disk 0". The arcs 25 and 26 are described with the radius 03 and Ot re-, spectively, and thearcs 25 and 26 divided into four portions of each 15, which maysignify the partial rotation of the disk 7. When now, the disk 1" is rotated from 15 to l9- also the,

point 20 wanders to 24,vwhile the entraining pins 0 stand at 13 and 14. Now one shank of the compasses is set in at 0 and the linesO-5,'

0+9 and 06, 010andsoon are taken, and

then the arcs are drawn. 'Thereupon the pieces153, 165, 17 9 and 20-4, 21-6,

22-4 respectively are taken one after the other and transmitted from 19 and 24 respectively on the corresponding arcs. Thus also the curved paths of the disk r are decided. i

The calculation of the helical guides g and i n is carried outin' simple manner. Assumed the adjusting member s will be shifted about 30 mm. parallel to the shaft and at the same time rotated about 60 the length for one turn will be found from the equation X 30 1 80 mm. Since 9 rotates about 60 g must simultaneously rotate 14? in opposite direction dur-' Q ing the rotation of 9 thusit will be moved Since now the center of' g has moved from 0 up to A, the dlsk 1' 1s nation of oneturr'lfils thus found to be for 60 lhflr 743, The length of the incligroove nustbe prolongedcorrespondingly; I claim:

1. An eccentric valveigear for steam engines'comprlsing a valvegear shaft, 'a sectmnaleccentnc, one sectlon of said eccentr1c being'mounted upon'said shaft, an eccentric strap, a second section of said eccentric having an inner diameter corresponding to the outer diameter of said first mentioned section and its outer diameter corresponding with the inner diameter of said strap, said two sections being eccentric to one another and rotatably mounted relatively to said valve gear shaft but in opposite direction to one another in order to secure any desired cut-off between the absolute zero-cut-ofi' and a given maximum cut-01f even while the engine is running and the leadmay be adjusted also corresponding to the cut-oft in question proportionally increasing or decreasing or may be held constant, an adjusting member mounted rotatively and longitudinally shiftable on the valve gear shaft with a helical connection,

said adjustable member having a curved slot L guide arranged to act on the said second section and said adjustable member havlng a further helical connection of different incli- .l nation arranged to act on the said first section, a fork for operating said adjusting-memo said disk, a socket on the first mentioned sec 7 tion of the eccentric forming a boss surrounding the inner part of the valve gear shaft, a hollow boss on the disk fitted on the said socket and connected thereto by a helical connection.

2. An eccentric valve gear for steam engines comprising a valve gear shaft, a sectional eccentric, one section of said eccentric being mountedupon said shaft, an eccentric strap, a second section of said eccentric hav- 111g an inner diameter corresponding to the ISO outer diameter of said first mentioned section and its outer diameter corresponding with theinnerdiameter of said strap, said two seotions being eccentric to one another and rotatably mounted relatively to said valve gear shaft but in opposite directions to one another in order to secure any desired cut-off between the absolute Zero-cut off and a given maximum cut-off even while the engine is running and the lead may be adjusted also corresponding to the cut-oif inquestion proportionally increasing or decreasing or may be held constant, an adjusting member mounted rotatively and longitudinally'shiftable on said valve gear shaft with a helical connection therewith, said adj list-able member having a curved slot guide arranged to act on the said second section and said adjustable member having a further helical connection of difi'erent inclination arranged to act 011 the said first section.

In testimony whereof I have signed my name to this specification.

FREDERICO ANTON KOVVARICK.

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