US2186229A - Engine starting mechanism - Google Patents

Description

ENGINE S'1;ARTING MECHANISM Jan. 9, 1940.' H. BAER ET AL 2,186,229

ENGINE STARTING MECHANISM Filed July 28, 1957 2 Sheets-Sheet 2 Patented Jan. 9, 1940 UNiTED STATES PATENT OFFICE ENGINE STARTING MEcnANrsM HowardBaer, Jersey City, N. J., and Martin J.

Finnegan, New York, N. Y., assignors to Eclipse Aviation Corporation, East Orange, N.

4 Claims.

This invention relates to internal combustion engines and more particularly to starting mechanism for such engines of the larger sizes.

It is a general object of the present invention to provide a novel and improved starting mechanism of the so-called inertia type for use with internal combustion engines.

More particularly it is an object of the invention to provide an inertia type starter for use with internal combustion engines wherein the rotatable inertia element is initially brought up to speed by the action of expanding gases, but, instead of applying such gases directly to the inertia element, as in patent to L. M. Woolson No. 16 1,884,479 of October 25, 1932, we propose to apply the pressure iiuid to a single stroke piston having novel motion translating and multiplying mechanism associated therewith for indirect acceleration of the flywheel constituting the inertia element I5 and such acceleration to be completed prior to the application of any cranking effort to the engine to be started.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specification. wherein is disclosed `a single exemplary embodiment of the inventionwith the understanding, however, that such changesmay be made therein as fall within the scope of the appended claims y vithout departing from the spirit of the inven- In said drawings: Figure 1 is a vertical central section through a starter constructed according to the present invention;

' Figure 2 is a vertical view, partly in section, along the line 2-2 of Figure 1;

Figure 3 is a-slightly reduced top plan view of 4o the starter shown in Figure 2; and

Fig. 4 is a diagrammatic View showing an automatic meshing structure.

For starting large internal, combustion en gines, particularly those of the type used for aviation, there has been developed a so-called inertia starter wherein a small flywheel is suitably brought up to a speed of 15,000 to 20,000 R. P. M. by either an electric motor or a manual cranking operation and through reduction gearing to a member of the engine for cranking the same.

Such starters are Well-known, and one form is disclosed` in the patent to R. P. Lansing, No. 1,739,469, December 10, 1939. The main elements of such a starter have been shown in the is then connectedl present drawings, and the operation will b briefly referred to herein.

A portion of the engine casing yis shown at I0, to which is attached, by suitable fastening means, the main framework II of the starter mecha- 5 nism. This carries various subsidiary framework and casing parts attached thereto, as clearly shown. A member I2 of the engine is adapted to be cranked for starting the same and carries on its end a dog clutch I3 for cooperation with w .a complemental clutch member I4 on the starting mechanism.

A flywheel I5, shown at the r' t end of Figure l, is mounted on a spindle I6 ca rying a pinion I1 engaging with the face of a gear I8 having formed integral therewith the pinion I9 which drives the internal gear 20 journaled on the shaft 2| co-extensive with the shaft I2 of the engine. This gear has formed integral therewith a pinion 22 which engages a plurality of planet pinions 2o 23 which in turn mesh with an internal stationary ring gear 24. u

The planet pinions have their stub shafts at tached to the disc 26 having formed integral therewith the driving barrel 2l. This driving 25 barrel is connected by means of a friction clutch mechanism 28 with a shell nut 29. The purpose of the clutch mechanism is to pelmtvslppage between the parts 21 'and 29, in case suiiicient resistance to cranking is encountered, so that no 30 parts will be broken.

A screw shaft 30 is arranged within the shell nut and threaded at a steep pitch toerigage the interior threads on the nut. The complementary clutch member I4 has a tubular portion 35 32 splined as at 33 to the end of the screw shaft for rotation therewith.

It Will be seen that, if the flywheel is brought up to speed, the various parts associated therewith will be driven at progressively reduced 40 speeds until nally the screw shaft 30 is rotated and, by reason of its splined connection, the complemental clutch member I4 rotates therewith. An operating rod 35 extends through the shaft 2I and is provided with an operating link 36 adapt- 45 ed to swing with a rock shaft' 3l (Fig. 2) -to the outer end of which is secured a lever 38, the said lever having its lower end operatively linked to a piston rod 39 and piston 45 (Fig. 4) corresponding to the rod 26 and piston 2| of Re-issue Patent 50 No. 13,681, granted to William L. Stuller on January 27, 1914, and mounted in a cylinder 5I) corresponding toll Stullers cylinder 20, except that for the by-pass 30 of Stuller We substitute a vent 55 to atmosphere, and for the inlet pipe I4 of w Stuller we substitute a pipe 86 (Figs. 1, 2 and 3) hereinafter referred to. With such an arrangement it will be apparent that the fluid exhausted from the unit 46 (hereinafter more fully described) will act upon the piston 45 and the linkage leading therefrom to the lever 38, whereupon lever 38 projects the rod 35 to the left, forcing the screw shaft to the left, which can readily be done because of the steepness of the pitch between it and the shell nut. Under the action of the spring 31, the clutch member I4 and its sleeve 32 are projected to the left until engagement takes place between the two clutch members, and the energy of the flywheel is imparted to the cranking shaft I2 of the engine to start the same. When the engine starts and runs at a greater speed than the screw shaft 30, this shaft will be threaded into the hollow shell nut to retract the clutch parts and allow the engine to l run freely. In case the engine does not start,

the clutch can be disengaged by movement of the shaft 35 to the right for another trial.

For starting manually, a beveled pinion mounted on the shaft 4I engages bevel gear 42 which in turn meshes with a bevel pinion 43 mounted on the shaft 2|. An extension of the shaft 4I provides a head 44 for engagement by a crank whereby the flywheel can be brought up to speed and then the clutch engaged.

All of the mechanism just described is shown and described in the Lansing and Woolson patents above identifled; but the Lansing patent shows, as the primary means for accelerating the fiywheel, an electric motor; and the Woolson patent shows a gas receiving conduit feeding directly into vanes on the flywheel itself. In some aeroplanes it is not advisable or convenient to employ the Lansing method of acceleration, while the Woolson concept of acceleration (which has not been reduced to practice) involves material alterations in the flywheel itself, which alterations interfere with the inertia effect thereof. Moreover it is desirable to shield the rotatable starter parts, such as the flywheel, against possible damage thereto from particles of unburned powder, such as they would be exposed to if the Woolson teaching were to be followed.

To avoid these conditions, and at the same time retain the possibilities of high speed inertia operation, we interpose between the pressure gas receiving conduit and the flywheel a motion translating and multiplying mechanism including a sliding piston, a multiple screw assembly, and a step-up gear train, the latter being preferably identical with the gear train employed for manual acceleration of the flywheel, as in an emergency resulting from lack of a gas producing cartridge, or from any like cause.

As shown in Figure l, the multiple screw assembly shown specifically in the co-pending application of Howard Baer, Serial No. 147,570, filed June 10, 1937, and generally described herein, is shown as mounted in a sec-tional housing including cylindrical parts 46 and 41,'the latter having a flange 48 by which it is secured to the main starter framework Il as by bolts 48.

Cylinder 46 has a cup-shaped head 5I, with a cylindrical portion 52 to receive piston 54, said portion 52 being externally threaded to coactwith a correspondingly internally threaded section 56 of a triple section intermediate transmission member 56--51--58. A second screw 59 is driveably connected with the threaded section 58 by a multiple ball and groove connection 6I which permits the axial travel of the piston 54 but causes rotation of the screw 58 because of the balls assembled in a suitable cage and inserted in the helical grooves, the grooves being provided at each end with stops serving to limit the endwise movement of the cage. For a similar purpose threaded sections 52 and 56 receive balls 62 inserted in a similar cage, and 'also retained within its limits of movement by suitable stops.

An anti-friction thrust bearing 63 is preferably interposed between a flanged skirt 64 on the lower end of screw sleeve 59 and an annular seat formed in the upper portion of the framework Il, the said bearing 63 acting to take the axial thrust to which the sleeve 59 is subjected. A spring 66 has one end resting against the closure plate 61 of the cylinder 46, and its opposite end abuts a thrust ring on member 58, which in effec-t, through the sleeve 58, abutsthe outer race of a ball-bearing assembly 68 axially movable with but rotatably free of the piston 54, the intervening bearing balls facilitating free rotation of outer race 38 of the bearing, with tue thrust ring being possibly constrained to rotation by the natural twisting tendency of the spring 66, as the latter is compressed in the forward travel of the piston. Piston rings 69 insure against the loss of pressure as the piston moves forward, and also yieldably oppose any tendency towards rotation of the piston. f

Due to 'the bolted split clamp connection 1I between the cylinder 46 and the body 41, the for-- mer may be quickly detached for removing any fouling that may occur where combustible cartridges are used as the source of fluid pressure to move the piston 54.

As shown, the pressure fluid path leading to the lower portion of piston 54, or second piston 15 includes openings formed by cutting away the flanged forward end of the exhaust valve 12 to form fingers, whereby the fluid entering through conduit 13 (Fig. 3) to annular chamber 14, may also pass directly into the annular chamber between the rod 16 and the tube 11, which constitutes a centrally disposed extension of the piston 54, to which piston the fianged rear end of the tube 11 is connected by suitable screws or equivalent means, as illustrated; the forward end of the annular chamber thus formed having communication with the annular chamber 14 by virtue of the area surrounding radial projections formed on the forward end of the rod 16. The second piston 15 is provided with sealing rings 18 which in conjunction with restricted openings y 18 drilled through the lower end of screw 59 cre- Iates a cushion of air for the piston 15 when it reaches its extreme lower position while at the same time facilitating and permitting free sliding movement of the tube withinthe bore of sleeve 58 as the piston 54. moves' downward in the cylinder 46. The valve 12 is carried by the rod 16 .and is of such a length that with the parts in the positions indicated in Fig. l, a collar extending inwardly of piston 54 will bear against the fingersl on the valve 12 to hold said valve on the seat formed in the head 8|. At the commencement of an operative cycle of the motor, such' as is occasioned by the delivery of fluid pressure to the chamber 14, this uid pressure will tend to maintain the exhaust valve 12 closed: but as the piston nearly reaches the end of its movement, the collar will be brought into en'- gagement with the projections on the end of rod` corresponding inwardly extending projections or fingers for abutment with the radial projections on the rod 16 as the piston 54 approaches the end of its stroke, while at theA same time this construction permits constant clearance between the said collar and the rod 16 (as shown clearly yin Fig. 1) whereby the pressure iiuid is always free to pass between the chamber 'I4 and the bore. of tube 11--passage being first from chamber 14 to the bore (at the beginning of the cycle of operations) and subsequently in the reverse direction to allow the pressure iiuid to be exhausted in response to the opening of the exhaust valve 12 -that is, its removal from its seat in the housing 8I-by the engagement of the collar with the projections on the rod 16 at the end of the stroke of the piston 54 as above described. The exhaust valve having been thus unseated, an internal bead thereon (not shown) will engage the conical end of valve guide 82 to yieldably hold the valve in the open position, to permit exhaust by way of outlet passage 83, outlet ports 84 in the cage, and exhaust pipe 86.

The piston having completed its operative stroke, and the exhaust valve having beenopened, the piston will be urged on its return stroke by the coil spring 66. During this return movement, the exhaust valve being held open, the cylinder will be effectively scavenged. Due to the action of the parts 12 and 82 the valve will remain open until such time as the piston collar is brought to bear against the ngers at the lower end of valve stem 12 for again seating the valve. This insures closing movement of the valve at the time the piston has substantially completed its return movement. It is thus apparent that the exhaust means is of such construction as to remain open during the major portion of the return stroke of the piston so as to insure substantially complete scavenging.

Having now described the construction of a conventional inertia starter of the character to which the present invention is weil suited, there remains to be noted the means for connecting the motion. translating and multiplying mechanism enclosed in cylinder 46 with the flywheel I5.

I n vthe form shown, said means takes lthe formv of an overrunning clutch preferably of the type shown and described in detail in Ithe patent to R. M. Nardone, No. 2,068,462, granted January 19, 1937, whereinr the hub 81 of the clutch is keyed or otherwise rigidly secured to a. shaft 88 integral with and extension cf the screw 59. 'I'he outer race 9I cooperates with the hub through means of the roller cage 89, the race being Journaled in bearing 92 of the casing framework II by means of anY extending shaft 93 thereof, which in turn is similarly connected with an additional shaft extension 94, journaled in bearing 96 and mechanism embodying the above described features of the present invention and capable of obtaining the above expressed objects. While the embodiment herein shown is of considerable practical merit, it is to be understood that various changes may be made in the construction arrangement and inter-relation of the parts entering into the invention without departing from the spirit thereof, the extent of the included variations being ascertainable by reference to the broadest of the appended claims.

What is claimed is:

1. In an inertia starterhaving a flywheel, an engaging member, and a connecting gear train, accelerating means for said flywheel, said accelerating means including a piston drivably connecting with said gear train, a housing for said piston, means for admitting pressure uid to said housing, means for exhausting said fluid from said housing, a second piston operable by the exhaust uid discharged from said housing when said rst piston has reached the limit of its stroke, and means operatively linking said second piston'to said engine engaging member to cause the latter to move to engine engaging position in response to movement of said second piston.

2. In an inertia starter having a flywheel, an engaging member, and a connecting gear train, accelerating means for said flywheel, said accelerating means including a piston drivably connecting with said gear train, a housing for said piston, means for admitting pressure duid to said housing, means for exhausting said fluid from said housing', a second piston operable by the exhaust fluid discharged from said housing when said first piston has reached the limit of its stroke, and -.means operatively linking said second piston to said engine engaging member to cause the latter to move to engine engaging position in response to movement of said second piston, said exhaust means comprising a valve actuating member` carried by and movable with said first-named piston.

3. In an inertia starter having a flywheel, an engine engaging member, and a connecting gear train, accelerating. means for said flywheel. said accelerating means including a single-stroke piston and means for converting the single stroke of the piston into rotation of the ywheel, means yior moving said engine engaging member into engine engaging positionQand means operable in response to movement 'of -said piston to the end of its stroke to produce energization of said moving means.

4. In an inertia starter having a flywheel, an' engine engaging member, and a-connecting gear train, accelerating means for said .ilywheel, said accelerating means including a single-stroke piston and means for converting the single stroke of the piston into rotation of the iiywheel, fluid pressure means for moving said engine engaging member into engine vengaging position, and means operable in response to movement of said piston to the end of its stroke to cause fluid to flow to said iiuid pressure means.

HOWARD BAER. MARTIN J. FINNEGAN.

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