US1705138A - Valve mechanism - Google Patents

Description

March 12 1929- c. H. RICH 1,705,138

VALVE macmmxsu Filed Jan. 10, 1927 2 Sheets-Sheet 1.

5 A57 30 A? 432 ,65 mo /z/ INVENTOR CARL H. 191011 I ATTbgEY Patented Mar. 12, 1929.

UNITED .STATESJPATEN'II- OFFICE.

AM; H. 3101:, or woacns'rnn, massacnusmrs, ASSIGNOR TO RILEY s'roxnn coma rom'rron', sums Application filed'laimary 10, 1927. Serial No. 160,046.

This invention relates to valve mechanisms, and more particularly to a device for controlling the operation of valves employed to admit fluid under pressureto an engine or the Valves are frequently usedin connection with vthe steam engines employed in operating the fuel feeding rams of furnace stokers. In such a construction a steam driven piston 0 is arranged to reciprocate a ram beneath a fuel hopper thus pushing fuel from the hopper into a furnace. A rotary cam shaft driven by a ratchet mechanism has been utilized to operate these valves, which may be of the poppet type. By controlling the speed of rotation of the cam shaft, 1t is possible to vary the time interval between suc- 'cessive strokes. of the fuel feeding ram, thus feeding into the furnace more or less fuel as :0 desired. Certain difficulties have been encountered in the past in the operation of devices of this type. As is well known, a ratchet driving mechanism is adapted to given positive inter- :5 mittent forward rotation to a drivenshaft. However, because of the inherent construction of such a mechanism, there is nothing to prevent the driven shaft from rotating ahead beyond the point to which it has been positively go advanced bythe'ratchet device. This undesirable advance movement or over-running'of the driven shaft will take place whenever a suflici'ent force is present to cause it. Such a force is providedby the valve spring which normally holds the valve against its seat and by the steam pressure acting on the valve. When the valve is opened by the action of the cam shaft, this sprin is compressed, and holds. the cam follower rmly against the cam. As the cam follower leaves the high point on the cam, and the valve starts to close, the spring and thesteam pressure tend to throw the cam shaft ahead. This action'frequentl takes place and is highly undesirable, as it makes it extremely diflicult. for the operator to control the-rate of fuel feed. It is evident 5 of fuel to the furnace sooner than if such action had not occurred. The operation of fhkelstoker is thus made erratic and uncontrol- It is accordingly one object of my invention orv woacns'rsn, uassacnusnrrs, A eoaronarron or- MASSACHU- VALVE .mnonanxsm. I

to overcome such difficulties and to provide a cam actuated valvem which over-running of the cam shaft inaforward direction is pre-- A further object of my invention isto provide a valve driving mechanism so arranged as to cause a quick opening and-closing of the valve and to permit adjustment of the time interval between successive valve openings.

With these and other ob'ects in view as will 7 be apparent to one skille in the art, my invention resides in the combination of parts set forth in the specification and coveredby the claims appended hereto. I

In accordance with my invention, 1 provide a cam controlled valve mechanism which is $6 constructed and arranged that a cam' 'cahnot over-run in its forward movement-lwhen the valve has been closed and thereby cause the valve to open too soon. This is accomplished by means of'a retarding device which hinders the forward motion of. the cam, and one simple device for this purpose comprises a spec1ally shaped cam and cam follower so ar ranged that the follower momentarily retards, or tends to lock, the cam in a'given position. For that purpose, I prefer to so shape i the valve actuating. cam itself that ,the follower which serves to move the valve is caught 1n a depression as soon as it passes the high point of the cam and thereby prevents furtl16I' advance movement of the cam except under the action of the driving mechanism, whlch Wlll 11ft the follower from the depression.

The lHVGlltlOIl further contemplates a driving mechanism for the valve actuatingdevice which permits an adjustment of the time interval between successive valve openings, thus making possible a regulation of the rate of fuel feed when the device is used in connection with a furnace stoker. 'In order to prevent damage to the valves and valve seats by wire-drawing of the fluid under pressure caused by a partially open valve, I provide a mechanism whereby the valves are given rapid opening and closing movements regardless of the position of the adjusting device. 1 One suitable arrangement found to be effective comprises a ratchet on the valve operating shaft driven by a pawl, the stroke of which is adjustable by means of a lost motion device, these parts serving to control the number of revolutions of the shaft in a given interval of time. A second ratchet fixed on the shaft and driven by a separate pawl, which moves through a fixed and full length stroke, is utilized to bring about the opening and closing of the valves. These pawls and ratchets are so constructed and arranged that the pawl of adjustable stroke advances the shaft step by step, slowly or rapidly as determined by its adjustment, until the valve is about to open, whereupon the pawl which moves always through a full stroke picks up its ratchet and moves the shaft to open the valve rapidly. The valve is closed rapidly in a similar manner. I

Referring to the drawings illustrating one embodiment of my invention, in which like reference numerals indicate like parts Fig. 1 is a side elevation, partly insection, of a poppet valve actuating mechanism;

Fig. 2 is a section on the line 22 of Fig. 1, parts being broken away for clearness of illustration Fig. 3 is a top plan view of the device shown in Fig. 1 and Fig. 2', with the cover plate removed; i

Fig. 4- is an enlarged perspective. view of the pawl frame;

Fig. 5. is an enlarged perspective View of the cams; i

Fig. 6 is an enlarged perspective view of the adjustable abutment member Fig. 7 is a front elevation of the apparatus,

showing the driving arrangement, parts:

being broken away;

Fig- 8' is a view of the ratchet; mechanism with the cover plate removed; Fig. 9 is a section through the ratchetmeclr anism on the line. 9+9 of Fig. 1 and Fig. 10 is a diagrammatic side elevation. of. a'stoker to which my invention is, applicable.

In the drawings I haveillustrated; a; device particularly adapted for" use with; a; furnace Stoker having a reciprocating; steam driven fuel feeding ram. The flow of steam to; the:

steam cylinder is controlled by a set of pop-- pet valves which are actuated by rotary cams. The cams are driven by a In the embodiment illustrated, a, casing; 151

' is arranged for the cam device and v this casthe cam roller,

ratchet. mechanism which provides a suitable adjustment for the. I rate of fuel feed. a

a removable top cover;

i A horizontal. ro-

tatable cam shaft 18 is su ported in suitable bearings 20 and 21 on the casing, and arranged to be driven by a ratchet mechanism which will be described later. Valve actuating cams may be keyed to this shaft and adapted to rotate therewith within the casing. I have shown two such cams 26 and 27, and for convenience joined by a central hub 28. A stationary rod 30 is mounted in the casing above shaft 18 and parallel thereto. Rocker arms 82 and 33 are pivotally mounted on this rod, and provided atone end with cam followers or rollers '35 which contact with the cams. The 0pposite end of each rocker arm contacts with the enlarged head 37 of an upper push rod 38 which is mounted for vertical sliding move ment in the casing 15.

Below casing 15' and attached thereto, I have illustrated diagrammatically a poppet valve mechanism, which. may be of any suitable construction. This may comprise a casing provided with removable valve seats 46. As shown, there may be four poppet valves 48 mounted on valve stems 50. These valve stems slide vertically in bearings 51 on the casing. Suitable packing 53 is held in place by glands 55 to prevent leakage of steam along the valve stems. Valve springs 56 hold the valves normally against their seats. The valves may be arranged in pairs, and each pair of valve'stems may make contact at their upper ends with tached to a lower push rod. 61. Each lower push rod is mounted for vertical sliding movement directly beneath an upper push rod 38.. A slight gap is. normally allowed between the npper and lower push rods to ensure complete closing of the valve.

In order to cause the valves to open at the proper time, each cam 26 and 27 is provided with a high point (Fig. 5). It is evident that as this high point moves out from under there is a decided tendency for the cam shaft to be thrown ahead by the force of springs 561 and by the pressure of" steam against the valves. This. tendency is particularly pronouncediwhen the follower drops rapidly as it leaves the high point, to: provide th desired feature of rapid valve closing. In: order to overcon ie this difficulty, and provide a. retarding; device, I arrange; a spring 66 to: holdeach push rod 38- against. its corresponding, rocker arm, and each: roller against itscorrespondiug cam, and I alsoprovide a recess or depression 67 on the dropisideof and adjacent to the high point 65. As the valvecloses,

held therein by spring. 66*,thus-preventing the cam shaft from being advanced undesirably by the spring action and steam pressure. This recess does not hinderi thei operation of the I in manufacture they may be and the valves start to close,

cam is so shaped that the a cross bar 60 attheicam roller drops from A the high point directlyii nto this recess, and is nism, as the cam roller is made comparatively large in diameter, and will roll out of the re cess without causing excessive resistance.

In order to operate the cam shaft, I provide a driving mechanism which will advance the cam shaft intermittently through steps which are adjustablein length. As difiicultywould be caused by wire-drawing when operating on the shorter steps, I arrange the driving mechanism in such a way thatthe valve is given a rapid. opening and closing movemen under all conditions of adjustment.

One formof cam driving mechanism may comprise a ratchet casing 7 0 and cover plate 71, pivotally mounted on the shaft 18 between a collar 72 and bearing 20. Casing and plate 71 are provided with extending arms 7.4 and 75respectively, connected at their ends by a pin 76, and are arranged to be oscillated by a suitable device, such as shown in Fig. 7 This may comprise a supporting frame 78, a worm 79 provided with a pulley 80, a worm gear 82 provided with a crank 83, and a connecting link 85. The pulley may be driven by anysuitable source of power.

Two ratchets 87 and 88 are keyed to the shaft 18 within the casing 70. Apawl 90, provided with a weighted tail 91, is pivotally attached to the casing 7 0, and contacts with ratchet 87. A pawl 92 is pivotally mounted on a pawl frame 9 1 by a screw 95, and contacts, with ratchet 88. This pawl frame, which is shown in detail in Fig. 4, is provided with a boss 97 having a tapped hole 98 and a flat portion 100. A portion 102 of the pawl frame may be enlarged as shown to counter-balance the weight of the boss 97. The pawl frame is mounted on the adjustable abutment member 105, shown in detail in Fig. 6, and is free to rotate thereon. This member 105 is arranged to oscillate with the casing 70 and plate 71, and is preferably mounted for adjustment relative thereto. One means for accomplishing this comprises an adjusting knob 108, at-

I tached to the member 105. This knob is provided with a radial bore in which is located'a ball 110 held outward by a spring 111 into one of a series of notches 114 in the cover plate 71.- These notches are preferably spaced angularly the same as the teeth on ratchet 88. r

and the numerals shown in Fig. 7 correspond with the number of teeth through which the cam shaft will be advanced at each stroke when the knob 108 is at that particular notch.

' A. fixed abutment is provided by a shoulder 120 on the inside of casing 70, and this shoulder is so located as to strike against pawl '92 on the working stroke, thus acting through ratchet 88 to rotate'shaft 18 ahead. .An adjustable abutment is provided by a radial projection 121 on the member 105. This projection is arranged to strike against-the flat poition 100 on the pawl frame 94 on the return or idling stroke. In this Way, a lost motion device is provided, the pawl 92 causing the shaft 18 tobe rotated ahead at each working stroke an amount depending on the adjustment'of the knob 108. i

As shown in Fig. 9, the ratchet88' has a plain portion 125 which is not provided with teeth, and the ratchet 87 has three irregularly spaced . teeth 127, 128 and 129. This construction ensures quick opening and Iclosing movements of the valves regardless lof the adjustment of knob 108. These parts are so arranged and proportioned that when pawl contacts with tooth 127 it im-' mediately moves the high point 65 on cam 27 under its corresponding roller and opens the valves actuated thereby. On the next working stroke pawl 90 contacts with tooth 1 128, which closes the valves just mentioned and opens the valves actuated by cam 26. On the next working stroke, provided knob 108 is in one of the lower numbered notches (see Fig. 7), pawl 90 contacts with tooth 129 and closes the valves previously opened. In case knob 108 is in one of the higher numberednotches, the final valve clo sure is effected by pawl 92 instead of pawl 90. At each rotation of the camshaft, pawl 92 rides up on the plain portion 125, allowing pawl 90 to bring about the opening of the valves actuated by cam 27. As a result, pawl 90 always causes the valves to open at each rotation of the cam shaft, and this action is unafiected by the length of the steps by which the shaft is advanced. Moreover, the valves are given a rapid opening and closing movement under all conditions of adjustment, thus avoiding the diffculties caused by wire-drawing.

It is desirable to prevent any possibility of backward rotation of the cam. shaft 18 during the idling stroke of the ratchet driving mechanism. For this reason I prefer to provide an additional ratchet 131 which is keyed to the cam shaft, and arranged to cooperate with a pawl 132 pivotally mounted on the casing 15. While this ratchet mechanism hasbeen described for'operating poppet valves, it is to be understood that it may be used with various types of valves which are operated by a rotary device.

My invention is particularly applicable to a stoker of the steam-driven type, shown diagrammaticallyin Fig. 10. Such a stoker may I comprise a steam cylinder 135 joined to a ram case 136. A piston reciprocates in the cylin der and drives a ram-in the ram case, thus forcing fuel from the hopper 188 throughthe wall 140 of a furnace, in a Well-known manner.

ent from the above disclosure. The pulley 80 is driven from any desired' source of power, and preferably from the same engine which drivesthe forced draft fan used incon nection with the stoker. The rotation of pulley 80 operates through the mechanism The operation of the device will-be apparengages tooth 127 and quickly opens the first set of valves. This admits steam to the cylinder 135 and causes the ram to push a charge of fuel into the furnace. On the next working stroke of the-ratchet mechanism, pawl SJOengages tooth 128, closing the first set of valves and opening the second set. This admits steam to the other end of cylinder 135 and withdraws the ram to its original position. The next stroke closes the second set of valves, and this closure is effected by pawl 9.2 or. pawl 90 depending upon the adjustment ofknob 108. Even though this knob be adjusted in one of the lower notches, say numa her 1, so as to give only a very slight advance movement to the ratchet at each stroke, the

valves will be quickly opened and quickly closed at the proper time by pawl 90, which will make contact with tooth 129 before the shoulder 120. has reached pawl 92. In other words when the pawl hil operating ratchet 88 moves through a short stroke, then, in

view of the fact that the other pawl 90 is always moving through a full length stroke,

' the latter seizes the ratchet 87 as soon as it 'meets one of the teeth thereon and immediately advances the cam shaft to the end of its stroke, whereas the pawl 92 is limitedin its movement to a short stroke by the adj usting device and so cannot apply force to its ratchet before the other pawl moves it. On such a short stroke, as well as on a full stroke,

- the pawl 92 picks the ratchet around a slight amount at each stroke until the cam follower approaches the high point on the cam,

whereupon the other pawl comes into play and moves the ratchet ahead at a single stroke until the valve is wide open. The next stroke of the pawl 90 closes the valve, after which the pawl 92 comes into play to advance the ratchet slowly. As each set of valves is closed, and the corresponding cam roller drops off the high point on the cam, the roller immediately enters the recess 67 in the cam through the action of spring 66, thus preventing the overrunning or throwing ahead of the cam shaft by the action of the springs andstcam pres sure. i 7

Having thus described my invention, what I claim as new and desire to secure by Let ters Patent, is:

1. In combination, a valve, a cam device for operating said valve, a ratchet mechanism for driving said cam device, and a retarding device to prevent over-running of the cam device beyond the point to which it is ad vanced by the ratchet mechanism.

2. In combination, a valve, a cam device for-operating said valve, a ratchet mechanism for driving said cam device, and a cam follower, said cam device being provided with means arranged to cooperate with said cam follower and prevent undesired advance movement of'the cam device.

8. In combination, a valve, a rotary cam shaft for operating said valve, a ratchet device for driving said cam shaft, a member on said shaft provided with a depression, and a follower arranged to enter said depression and prevent undesired forward rotationof the cam shaft.

4. In combination, a poppet valve, means for holding said valve normally closed, a cam shaft, a ratchet mechanism for driving said cam shaft, acam on said shaft provided with a high point to open the valve and a depression, and a cam follower adapted to enter the depression, said depression and follower being so arranged that just after the high point of the cam passes its operative position the follower will engage the depression and prevent the cam shaft from being undesirably rotated ahead.

5. In combination, a poppet valve, a spring to hold said valve normally closed, a cam shaft, a ratchet mechanism arranged to drive said cam shaft, a cam on said shaft-arranged to operate said valve and provided with a high point and a depression, a cam follower,

and a spring arranged to hold said follower in contact with said cam, whereby undesired forward rotation of the cam shaft is prevented, said depression being so shaped that further forward movement of the ratchet will raise the follower from the depression and permit rotation of the cam shaft.

6. In combination, a valve, a rotary means lOD for actuating said valve, means for advancing said rotary means ahead intermittently, means for ad usting the amount of each advancement, and means for causing each opening and closing movement of the valve to be rapid regardless of the position of said adjusting means.

7. in combination, a poppet valve, a rotary cam shaft provided with a cam for actuating said valve, and a ratchet mechanism for driving said cam shaft, said mechanism comprising means for advancing the cam shaft intermittently through steps of an adjustablelength and means for effecting rapid opening and closing movements of the valve regard-- less of the length of said adjustable steps.

-. 8. In combination, a valve, a rotary shaft arranged to operate the valve, a ratchet on said-shaft, a pawl arranged to drive said ratchet, a lost motion device for moving said pawl through an adjustable distance, a second ratchet mounted on said'shaft, and a pawl arranged to drive said second ratchet,

llO

said parts being so constructed and arranged that each opening and closing movement of the valve will be rapid regardless of the adjustment of said lost motion device.

9. A valve operating device comprising a rotary shaft, two ratchets fixed thereon, one having a pawl movable through a stroke of variable length operatively associated with one ratchet, means to vary the length of such stroke, a second pawl operatively associated with the second ratchet and means to move the second pawl through a fixed stroke, said parts being so constructed and arranged that the pawl of Variable stroke will move the shaft at a desired rate of advancement to a certain point-whereupon the pawl of fixed stroke will operate to move the shaft to open and close the valve rapidly.

10. A valve operating device comprising a valve, a rotary shaft operatively connected to move the valve, two ratchets fixed thereon,

ciated with the first ratchet, means to move .the pawl through a stroke of variable length to turn the shaft at a desired rate, a second pawl operatively associated with the second ratchet, and means to move the second pawl through a full stroke, the teeth and non-operative portion on the second ratchet being so arranged as to permit the first pawl tomove the shaft during the period that the valve is closed and the second pawl to engage a tooth on its ratchet and move the shaft uninterruptcdly to open the valve rapidly and then engage a second tooth to close the valve rapidly.

Signed at Worcester, Mass, this 8th day of January, 1927.

CARL H. RICH.

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