US1898697A - Apparatus for changing the pitch angle of reversible-blade screw propellers - Google Patents

Description

2- Sheets-Sheet l M. D. THOMPSON APPARATUS FOR CHANGING THE PITCH ANGLE OF REVERSIBLE BLADE SCREW PROPELLERS Filed Nov.

Feb. 21, 1933.

INV E NTO R Milton D.Thomjzson.

WTTuRmrY.

. Feb. 21, 1933. J M; D. THOMPSON 1,898,697

APPARATUS FOR CHANGING THE PITCH ANGLE OF REVERSIBLE BLADE SCREW PROPELLERS Filed Nov. '9. 1931 Z'Shefls-Sheet 2 IHVEHTOR.

JIilton D. Thompson.

Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE MILTON D. THOMPSON, OF FAIBHAVEN, MASSACHUSETTS APPARATUS FOR CHANGING THE PITCH ANGLE OF REVERSIBLE-BLADE SCREW PROPELLEBS Application filed November 9, 1931.

I The invention hereinafter to be described relates, in general terms, to propelling machinery for Various kinds of water craft,

and deals more particularly with certain im-- solid propeller, or one in which the blades are cast integral with the propeller hub. In most cases this is quite satisfactory on account of the fact that the steam engine is not only reversible with respect to the direction of rotation of its shaft but is also susceptible of being driven at rotation.

The modern trend, however, is away from steam and toward the use of gas or internal greatly varying speeds of combustion engines and these being generally irreversible giowe'r agents and more economically and e ciently operated at a constant or uniform speedof rotation it becomes necessary to provide certain apparatus by means of which the driving effort of the propeller may be made variable so as to move the vessel at different speeds, and also to supply means to apply this driving effort in opposite directions in order that the craft may be moved either in a forward or backward direction.

Reversing and speed reducing gear sets are sometimes employed to accomplish the above objects, although in certain respects they lack theessential requirements which are embodied in other blade-reversing mechpower, and a solid propeller in these instances becomes a drag, and necessarily greatly reduces the speed of the craft when operating wholly by wind power.

In the present invention I employ a differential gear mechanism which is power driven from the main shaft" of the engine and which Serial No. 578,868.

can be made to actuate a feed screw for the purpose of changing the pitch angle of the blades of the propeller while the engine is operating at fullor normal speed.

By applying a brake to either one, singly, of two geared brake drums the feed screw is set in motion and moved longitudinally of the shaft and the blades turned on their axes in a direction determined by which of the two drums is restricted in its rotary movement..

Upon releasing the brake the blades remain 1 in a positively secured and predetermined angular position.

An automatic feed stop arrangement prevents further axial rotation of the blades when either extreme of pitch angle, forwardly or backwardly, is reached, and an indicator shows the particular pitch angle or lead at whichthe blades are disposed at the time.

Facilities are also provided for correcting the pitch of each individual blade, and this is a feature which is of superior advantage in the manner of attaining and preserving correct balance of the propeller wheel.

The character of the invention may best be understood by reference to the description found in the following specification when taken in connection with the accompanying drawings in which is disclosed anembodiment thereof which, at the present time, I consider preferable to other possible forms in which the invention might be carried out.

In the drawings- Fig. 1 is a sectional plan view of my apparatus;

Fig. 2 is an end view of the propeller hub, the cap being removed to show the link block;

Fig. 3 is a section on line 3-3, Fig. 1.

Fig. 4 is a composite view, in perspective, showing the foot of the blade and the split collar which secures it to the propeller hub;

Fig. 5 is a diagrammatical view showing the method of connecting the link block to the blade;

Fig. 6 shows, on an enlarged scale, the eccentric pin which is employed to locate the link in various positions on the link block;

Fig. 7 is an end view of a propeller blade shown in full lines to r epr.esent neutral or feathering position, and in dotted lines for ahead and astern positions, respective- 1 YFig. 8 shows an alternate method of securing the two parts of the housing together;

Fig. 9 is afull plan view of the apparatus, the propeller not being shown;

F ig. 10 is a side view of one of the brake bands;

Fig. 11 is a detail view of the automatic stop mechanism;

Fig. 12 shows the cammed face of the brake band ear;

Fig. 13 is a perspective view of the slotted sleeve-actuating lever for the automatic stop mechanism;

Fig. 14 illustrates the position of the indicating elements when the blades have moved to one extreme outward position of pitch angle;

lgig. 15 is a section on line 15-15, Fig. '9, an

Fig. 16 is a perspective view of the indicator end of the feed screw.

Similar reference characters are employed to identify like parts in all the difierent views of the drawings.

Referring to the drawings, and particularly to Fig. 1, it will be observed that the principal working parts of the mechanism are enclosed in a longitudinally and centrally split housing consisting of two similar structures, 1 and 2, which, when the apparatus is in operation is partially filled with a proper lubricant.

On each end of the housing proper are extended split hubs 1a and 2a and 1b and 2?), respectively, and through the hubs is a bore 3 a portion of which, at 3a, is made square 1n cross section.

On the extreme inner ends of the hubs 1a and 2a are semi-circular flanges 4a and 4b which are secured to the solid circular flange coupling 5 fixed on the main engine shaft 6.

Operating in the bore 3 is a feed screw 7, on the outer end of which is fixed the feed rod 8 extending through the bore 9 in the propeller shaft 10 to the link block 11, which latter is slidably mounted in the hub 12 of the propeller.

Disposed between the bosses 13, 13, is a bevel gear 14 which is screw threaded in its bore and operates on the feed screw 7. Meshing with and disposed on opposite sides of the gear 14 are two smaller bevel gears 15, 15, which are fixed, respectively, on shafts 16, 16 which are journalled in bearings 17, 17.

These shafts diverge, relatively, toward the forward end of the housing and on one end of each is fixed a gear 18, these two gears (18) meshing with and located on opposite sides of the external gear 19 which is secured to the brake drum 20. On the inner ends, respectively, of the shafts 16 are gears 21, these meshing with the internal gear 22 which is secured to the brake drum 23.

Operating, respectively, on the brake drums 20 and 23 are brake bands 24, 24, a side View of one of which is shown in Fig. 10. On the face of the band projects an ear 25 fixed on a supporting standard 26, and on the open ends of the band are other ears 27 on one of which is a cammed face (see Fig. 12) adapted to engage the reversely camme surface of the brake arm 28. A bolt 29 passes through both the ears 27 and the cammed brake arm operates between the head of the bolt and the cammed car so as to effect, when the arm is swung in one direction, a closing together of the brake bandends and tightly bind the band to the drum. An upstanding lever 30 is employed to actuate the brake arm.

To secure the two halves of the housing together I employ rings 31 and 32 having screw threaded engagement with correspondingly threaded portions 33 and 34, respectively, on the ends of the housing membersl In Fig. 8 is shown a modification in the method of securing the two members of the housing together, bolts 35 being employed in this instance.

The propeller blade 36 is axially rotatable in a split collar 37 which surrounds the shank or reduced portion of the foot of the blade, 38, and is screw threaded on its periphery into the opening 39 in the hub 12. A set screw 40 prevent rotation of the collar and a cap 41, threaded to the end of the hub, at 42, seats on the shoulder 43 and prevents backing out of the screws 40.

It will be observed that the link block 11 is provided with a guide rod 44 which passes through the end of the cap. This prevents any pumping action which might occur was the hole not carried completely through the cap.

To hold the link block 11, which preferably is made triangular in cross section, against rotation in the hub 12 I provide indents 45 in which the apices of the block seat and in which they may longitudinally slide.

On the inner face of each blade, at the foot end, is a crank pin 46 and on each face of the link block is an eccentrically mounted pin 47 Operable over and connecting with both of these pins is a link 48.

Referring to Figs. 5 and 7 it will be seen how longitudinal movement of the link block rotates the propeller bade. The small circle a: represents the axis of the blade and around this central point swings the pin 46 on the blade. When the pin 46 is positioned on the radial line a the blade is set at extreme working pitch ahead, and when on radial line b it is on extreme working 'pitclrastern.

When it is desired to feather the bladesfore and aft-the pin 46 is moved to radial.

line a, in which position the link rests on the stop pin 49. The eccentric pin 47 moves longitudinally, backwardly and forwardly with the link block, in exactly the same manner as would the wrist-pin in a crosshead of a steam engine; and to complete the analogy, the link 48 serves in the same capacity as does the connecting-rod of the engine.

Due to possible inaccuracies in locating the pins or to slight dissimilarities in the pitch of the blades when molding or finishing I have found that it is 'quite essential that means be provided to bring all the blades to a uniform pitch angle after assembling them on the propeller hub.

To accomplish this object I make the pin 47 eccentric (see Fig. 6) and by slightly turning it in its position in the block it has the effect of re-positioning the linkas shown in dot and dash lineswith a consequent change in the angularity of the blade in its position on the hub of the propeller.

The actuation of the brake arms .28 to effect difi'erent changes in pitch angles of the" blades is a manual operation performed by the engineer or other attendant in charge and he is supposed to release the brake drums and stop the feeding of the feed screw when the desired pitch angle has been reachedas visually disclosed by the indicator. But in careless operating he might neglect to throw off the brake at the proper time with the result that damage might be done to the parts. For this reason I consider it quite essential that the automatic stop-feed mechanism be incorporated in the structure of the apparatus.

In Fig. 14 the feed stop arm 50 is shown contacting with the collar 51 at a point indicated by the pointer as being the extreme pitch of the blade when working astern.

Regardless of whether the engineer retains his grip on the brake lever after reaching the extreme working pitch point, or not, the

automatic safety knock-off will act to release the brake at the proper time.

In operating the ahead brake drum the automatic knock-ofi' or feed stop arm .50 will act on the collar only when the pin 16 has reached a position coincident with the radial line a. (Fig. 5) or at a point at which the blades. are feathering; but unless the vessel is sup lied with a large surplus of power it would be extremely difiicult to operate the propeller with the blades standing fore and aft as their flat faces would be presented tothe water. In cases of emergency the collar 52 would act, however.

When the propeller shaft is not rotating and it is desired to change the pitch of the blades-as for instance, in a sail equipped and the chain of gears set in motion to move the screw 7 in either direction.

The automatic sto parts are shown in neutral position in igs. 1 and 9. In Fig. 11 the screw 7 has been moved toward the propeller, the astern brake band having been tightened, causing the slotted lever 53 to swing and move the grooved sleeve 54 forwardly and the feed stop arm 50 into the position shown in Fig. 14.

By reference to Fig. 15 it will be noted that there are two of the slotted levers 53, one operating in a depression 55 in the housing part 154- and another in a like depression in the housing part 2a. This prevents cramping of the sleeve as -it moves over the housing hubs.

The numerals O, 10, 20 etc. disposed in an are on the indicator boards B may represent either pitch angles or leads in inches of the screw shaped blade; they are of considerable advantage'to the engineer in correctly manipulating the friction bands in order to bring the blades to some predetermined position.

The coupling 56 joins the housing parts,v

1 and 2, to the propeller shaft 10, keys 5'? and set screws 58 being employed to securethe parts together.

It will be observed by reference to Fig. 3 that the screw member 7 is made square adjacent ,the portion 3a of the bore. This is to prevent turning of the screw when the gear Let us assume, first, that the engine ro- 1 tates right hand, that is, according to the direction indicated by the arrow on the shaft coupling, shown in Fig. 9 also let it be understood that in this instance the astern brake band has been tightened, as shown in dotted lines Fig. 9. Now, the engine being operated, all parts of the apparatus supported on the main shaft line, except the two brake bands, the brake drum 23 and the gear 22, are revolving.

But, while the gears 21 rotate bodily with and around the axis of the housing parts, they also rotate on their own axes, due to their engagement with the gear 22 which for the time being is stationary as it is fixed on the drum 23, which is being held rigid by the band.

The shafts 16 thus rotate at this time in their respective bearings and on their own axes, and the gears 15 being fixed on these.

shafts and also in engagement with the gear 14, impart v rotary movement to the latter which acts as would an ordinary nut turning on the feed screw 7, the latter rotating with but not in the housing parts.

There is, therefore, a longitudinal movement given the screw 7 which is communicated by means of the feed rod 8 to the link block 11, and through the instrumentality of the links 48 interconnecting the pins 46 and 4:7 in the manner hereinbefore set forth, a rotary movement of the blades is finally accomplished, turning them in the present instance so that they lie in coincidence with the line b-Z), Fig. 7-which represents the blade when in left hand pitch, the line w-a, Fig. 7 corresponding to right hand pitch angle. I

The counter-rod 57 supporting the collars 51, 51a and 52 may be supported in suitable hea rings (not shown), the yoked ends of the brake arms straddling the rod and engaging the collars when the brakes are being operated.

The embodiment herein described is, of course, primarily illustrative and my invention is, obviously, capable of interpretation in a wide variety of structures.

What I claim is:

1. In apparatus of the class described adapted for use on shafts for screw propel- .lers having detachable blades, comprising a housing secured to and revoluble with said propeller shaft, a feed screw in said housing extending through a bore in said propeller shaft to said propeller, a gear having a threaded bore mounted on said feed screw, a drum rcvoluble on said housing, a gear fixed to said drum, a shaft, the axis of which is inclined from the axis of said propeller shaft, journalled in said housing, two gears fixedly mounted on said inclined shaft adapted to engage, respectively, the two first mentioned gears, and means whereby, when said propeller shaft and said housing are revolving, said drum may be held against. rotation, causing a differential gear action to be had between the respective gears, the first gear mentioned rotating on said feed screw and moving it longitudinally in one direction in the bore of said propeller shaft.

2. In apparatus of the class described adapted for use in connection with the operation of changing the pitch angle of the blades of a reversible screw propeller mounted on a hollow shaft, comprising a housing mounted on said shaft and having a central bore therein, a feed screw operable in said central bore,a gear, having a screw-threaded bore, mounted on said feed screw and held against longitudinal movement in said housing, a differential gear set in said housing operable to rotate said feed screw gear on said feed screw in two directions while said housing is revolving in but one direction, a feed-rod connecting with said feed screw and extending through said hollow shaft to the interiorof the hub of said propeller, a link block fixed on the outer end of said feed rod and having faces the number of which correspond to the number of blades in said propeller, an eccentrically mounted pin on each face of said link block, a crankpin on the inner end of each of said blades, and a link interconnecting the two said pins, said eccentrically mounted. pin providing means to re-locate said link on and longitudinally of said link block whereby adjustments may be made to bring all of said blades into uniformity with respect to their pitch angles.

3. In apparatus of the class described adapted for use on hollow shafts for screw propellers having reversible blades comprising a centrally and longitudinally split housing, means to secure the two halves of 'said housing together, a central bore through said housing, a feed screw operable in said bore and having a portion extending to and into the hub of said propeller, a gear having a threaded bore mounted on said feed screw, two brake drums revolubly mounted, respectively, on the two ends of said housing, a gear fixed on'each of said brake drums, interiorly of said housing, two shafts journalled in said housing on opposite sides, respectively, of said feed screw, their axes being inclined from the axis of said screw, three gears fixedly mounted on each of said inclined shafts, one on each end and the third intermediate the length of the shaft, one end gear adapted to engage, externally, one of the brake drum gears and the other end gear meshing, internally, with the gear on the oppositely disposed brake drum, with the intermediate gear on each of said inclined shafts meshing with the said feed screw gear, a brake band on each of said brake drums, means to tighten, singly, either of said brake bands and hold the drum on which it is mounted against rotation while said housing is revolving, a link block on the end of sald feed screw extension, and means to connect said link block with each of the blades of said prope ller whereby they may be rotated, axially, in their mountings on the hub of saidpropeller.

4. In apparatus of the class described adapted for use on hollow shafts for screw propellers having reversible blades comprising a housing mounted on said shaft, a differential gear set in said housing, a feed screw axially mounted in said housing and adaptable of longitudinal movement, only, therein, a drum revoluble on each end of said housing, a brake band on each of said drums, a brake arm on each of said bands adapted when swung in one direction to cause said band to become tightened on and hold said drum against rotation while said housing is revolv ing, the stopping of rotation of one drum acting, in association with said-gear set, to

move said feed screw in one direction, and by the stoppage of the other drum to reverse the movement of said feed screw longitudinally,

and a pivotally mounted feed-stop arm one end of which is actuated by said feed screw and the other end operable to automatically release the brake band on. the operating drum whereby the longitudinal movement of said screw ceases.

5. In apparatus for changing the pitch an- I gle of reversible blade screw propellers comprising a hollow shaft on one end of which a propeller is mounted, a housing secured to the opposite end of said hollow shaft, a feed screw trarersing said housing and said hollow shaft, interiorly of both, a feed gear, having a screw-threaded bore, operable on said feed screw, means to hold said feed screw against longitudinal movement in said housing, a brake drum revoluble on each end of said housing, braking means applicable to hold said drums, singly, against rotation on said housing, a dilferential gear set interconnecting and associated with both of said drums and said feed gear and arranged within said housing in such a manner that, when said housing is revolving, stoppage of rotation of said drums alternately will rotate said feed gear, respectively, in two directions, with a consequent and corresponding longitudinal movement of said feed screw, and means cooperating with said feed screw to release the brake on either of said drums aft er said feed screw has moved longitudinally in said housing a predetermined distance in either direction.

In testimony whereof I aflix my si ature.

MILTON D. THOMP ON.

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