US2284338A - Engine starting mechanism - Google Patents

Description

y 1942' R. M. NARDONE 2,284,338

ENGINE STARTING MECHANISM Filed Oct. 6, 1941 2 Sheets-Sheet 2 I IIHI I 7 112 INVENTOR.

I04 BY Romeo M. Nara/one 117 T] nnm(nnn 7 Patented May 26, 1942 I ENGINE STARTING MECHANISM Romeo M. Nardone, Westwood, N. J., assignor to Bendix Aviation Corporation, South Bend, 11111., a corporation of Delaware 1 Application October 6, 1941, Serial No. 413,872

3 Claims.

This invention relates to engine starting mechanism and more particularly to a starting mechanism of the inertia type, in which there is a period of energy storage in an inertia" element (flywheel, for example) prior to movement of the engine engaging, or cranking element, to cranking engagement with the member of the engine to which initial rotary movement is to be imparted.

In inertia starters as heretofore known an appreciable amount of energy accumulated in the flywheel is lost-first, through the slippage of an overload release clutch and secondly, by the fact that some energy remains unused at the moment when the engine "starts"; and even on the occasions when the cranking effort is continued until the flywheel energy is used, the energy remaining at speeds below 4000 R. P. M. is inefiective, due to the low engine cranking speed from that point down to zero. In other words, on such occasions, there is a failure of the engine to start. Further, inertia starters engage at maximum rotary speed, thereby imposing a torque value on the engine member which is normally above the slipping value of the overload release clutch. This tends to create a condition of shock, at first engagement.

Objects of the present invention are to make advantageous use of all the energy of the flywheel all the way down to zero flywheel speed; and to minimize the shock of engagement. The latter I propose to bring about by engaging the starter and engine jaws at zero rotary speed, thereafter increasing the rotative speed of the starter jaw.

Another object is to crank the engine at speeds over and above that which would normally obtain with a fixed gear ratio between flywheel and engine engaging jaw, the cranking speed being characterized by a tendency to increase during at least the initial stage of the run-down period of the flywheel, rather than to decelerate therewith, as has been the tendency heretofore.

Still another object is to produce a direct cranking action by use of energy from a prime mover additional tothe flywheel, said prime mover being operative, first, to accelerate the flywheel, and subsequentlyupon reversal in its direction of rotation-being instrumental in establishing connection between the starter and engine, and also in helping the flywheel to speed up the engine and continue to transfer energy thereto even after the flywheel has come to a complete stop, and so long as is necessary to insure effective starting.

These and other objects of the invention will become apparent from inspection of the following specification when read with reference to the accompanying-drawings wherein is illustratcd the preferred embodiment of the invention. It is to be expressely understood, however, that the drawings are for the purpose of illustration only, and are not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawings:

'Fig. 1 is a central sectional viewof a device embodying the invention;

Fig. 2 is a very partly in section and partly in elevation of a modified embodiment of the starter shown in Fig. 1; and

Fig. 3 is a diagram of electrical parts and connections applicable to control energization of the motor of Fig. 1 or Fig. 2. 20 The invention is illustrated in the accompanying drawings asembodied in a housing having an outer section 3 and an inner section 4 with a suitable flange 5 to receive bolts 6 for detachably connecting said sections. The inner section 4 is provided with a second flange 1 to receive bolts 8 for securing the starter to the crankcase of an engine, a portion of the latter being indicated at 9. Secured to one side (top, as shown) of section 3 is an electric motor l0 provided with a casing ll having a flange to register with a corresponding flange on casing section 3, and be supported thereby.

The motor may be of any suitable type embodying an armature shaft l3 provided with a 35 projecting, reduced portion it that is,rotatably mounted as by means of a suitable bearing IS in a transversely extending wall of housing section 3. Drivably connected to the reduced portion of the armature shaft is a pinion l6 that meshes with a bevel gear I! which, in the form shown, is integral with an internally toothed annular gear l8. Adjacent the member I 8 is a cylindrical boss l9 forming part of the end wall of housing section 3. The boss 19 supports therein a double bearing 20 within which rotates the hub 2| of the flywheel 22, also the shaft 23 to which said hub 2| is keyed as indicated. Said shaft 23 also has keyed thereto a ratchet toothed clutch element 24, and at its opposite end the shaft is formed into a pinion, as at 26, constituting the sunff or central element of a planetary system whose several planet pinions, as at 21 and 28, mesh with the orbital gear l8 heretofore referred to. A second ratchet element 3| is splined upon stationary sleeve 32 embedded in rear cover plate 33, and a smaller cover plate 34 holds in position a spring 38 which yieldably urges the ratchet element 3| into mesh with ratchet element 24, thereby restricting flywheel 22 to rotation in a single direction only.

A second planetary system includes a planet carrier 38 integral with a sun gear 39, and is rotatably mounted as by means of a bearing 4| on a stub shaft 42 that extends outwardly from. and is drivably connected to, a barrel 43 having a closed end 44, the stub shaft being integral with said closed end in the illustrated embodiment of the invention. Ball bearings 38 carried by the inner housing section 4 are preferably employed for rotatably mounting the barrel 43.

Gear 39 meshes with a plurality -of planetary gears 48 that are rotatably mounted on the barrel end 44 and mesh with an annulus gear 41 which is fixedly mounted within the housing by means of studs 48. Preferably three planetary gears 48 are employed, and one of these is shown of a ball bearing, as at 8| carried by a sleeve' which is countersunk at its inner end in barrel end 44. A screw 82 supports each sleeve, bearing and planetary gear. If desired, a retaining ring 83 for the bearings 8| may be provided, as an integral part of the screw receiving sleeves.

As shown, annulus 41 has two orbital tracks, the second being engaged by planet pinions 58 rotatably mounted (by parts similar to those supporting pinions 5|) to turn with carrier 38 above described, and each meshing with a sun gear 81 formed on one end of a shaft 88 connecting said gear with the carrier 88 of the planets 21, 28. A second ratchet clutch has one element 8| integrated with planet-carrier 38, the adjacent element 82 being splined to stationary boss 83 of transverse wall 84. Springs 85 urge clutch part 82 into engagement with part 8|, to restrict rotation of planet carrier 38 to a single direction. The electric motor I8 is, adapted to drive an engine engaging member 84 through the train of reduction gearing described above. The member 84 constitutes one element of a jaw clutch, the other element being formed by a member 88, carried by a rotating part of the engine to be cranked, such as the engine crankshaft or an extension thereof. There is also preferably employed the usual multiple disc clutch embodying a plurality of friction disks 88, a number of said disks being splined to the inner surface of barrel 43, and the remainder being splined to the outer surface of an interiorly threaded nut 1|. Resilient means such as a plurality of coil springs 12 and an adjusting nut 13, which is threaded into the inner end of barrel 43, are provided for varying the pressure with which disks 89 are mainshoulder formed interiorly of nut 1|. Preferably a coil spring 18 is interposed between jaw clutch member 84 and shaft 14, a portion of said spring extending into a recess formed in the inner end of the shaft, to yieldingly resist relative movement of the parts.

The starter is preferably provided with the usual oil sealing means for preventing oil in the engine crankcase 8 from seeping into the starter housing. This includes a cup-shaped member 8| that is preferably formed of metal and is provided with a flange 82 on the outer end thereof, said 'flange being adapted to be clamped between flange I of the starter housing and the engine crankcase. The inner portion of member 8| is ,bent inwardly toward jaw member 84, and is provided with a central opening which is slightly larger in diameter than the outer diameter of the head of jaw member 84.

In order to prevent seepage of oil through the central opening in member 8|, the latter preferably carries the usual washer of leather or the like, secured in any suitable manner to the shoulder provided adjacent the bend of member 8|. Normally-the inner portion of the washer is held in engagement with the adjacent surface of the head of jaw'member 84 by means of a sleeve which slidably surrounds the cylindrical portion 84a of the jaw clutch member and abuts at its outer end against a flange provided on nut The outer periphery of the head of member 8| is provided with longitudinally disposed slots adapted to receive radial lugs which project inwardly from the inner surface of a split-ring 8| that is supported on the curved lip of the oil seal member 8|. The several portions of the split ring 9| are preferably retained in position on member 8| by means of a surrounding resilient member, such as a coil spring 82, which rests in a circular groove formed in the outer periphery of said ring ill. The latter is adapted to rotate on the curved lip surrounding the central opening in member 8|; this construction being more fully illustrated in Patent No. 1,962,397 granted to Raymond P. Lansing on June 12, 1934.

There is also preferably provided the usual rod 88 which slidably extends through stub shaft 42, barrel end 44, threaded shaft 14 and a central opening in the hub member 8|. The inner portion of rod 98 is of reduced diameter to provide a shoulder which normally abuts against the outer end of shaft 14. The inner end of rod 98 is threaded to receive a nut which abuts the hub of jaw member 84 and coacts with shoulder to retain said member and shaft in operative relationship.

During flywheel acceleration, all planetary spiders are stationary and therefore the starter barrel 43 does not rotate. After proper flywheel speed is obtained, the direction of motor rotation is reversed by any suitable circuit arrangement (as-in Fig. 3 hereinafter described), as by cutting off the current in one set of field coils and sending it through a second set of field coils. When this circuit change is made, the motor rapidly .decelerates to zero, under the action of the reverse current, and the speed of gear |8 in its original direction of rotation is thereby decreased. This decrease in speed of gear l8 causes all planets to rotate, which rotation is of course communicated to the starter barrel 43. This results in immediate screw action at II, 14, whereupon starter jaw 84 starts to move forward into engagement with the engine jaw. Engagement is therefore at zero speed and zero torque; hence there is no slippage at clutch 69. However, during this deceleration of the motor to zero speed some flywheel energy is lost, due to the drag of the decelerating gear I8 upon the flywheel; but this loss is slight as compared with what is saved by reason of the absence of any slippage at clutch 69. After reaching zero speed the motor will start to rotate in the reverse direction, speeding up gear I8, also in the reverse direction, and thereby increasing the speed of the planetary system and hence of the starter jaw 64. Flywheel 22 will eventually come to a complete stop, but during the period of its deceleration the speed of gear I8 will approach that of gear 26 and eventually overtake it and pass it. In this way rotation of spider 59 is caused to continue even after the flywheel has stopped.

As the flywheel comes to zero speed, clutch SI, 24 takes hold and prevents its rotation in the reverse direction. Gear I8 continues to be rotated by the motor and the engine is cranked at a speed corresponding to motor speed divided by the ratio between it and the jaw 64. Direct cranking (from motor I to jaw 64) may thus continue until the engine starts. Maximum torque at the jaw 64 is a function of the maximum torque of the motor during its reversal, and the gear ratio between motor and jaw. This torque must in all cases be appreciably higher than the breakaway torque of the engine. Were it not so, the engine would not move, and all the energy in the flywheel would be expanded in rotating the motor armature against its electrical torque.

In some installations it maybe preferred to employ an added element to facilitate the action of reversing the direction of motor rotation after acceleration of the flywheel. Such an element may take the form of a brake engageable with a suitable surface on the armature shaft or other rotating part of the motor; and as illustrated in Fig. 2 such a brake may consist of a pair of cone clutch elements MI and I02 normally held engaged by springs I03; said springs being yieldable to permit movement of the outer element I02 to the disengaged position upon passage of current through a winding I04 of an electromagnet whose plunger type armature is thereby shifted to produce such disengaging movement of the element I02, through the action of a yoke I06, pivotally mounted at I20, and mechanically linked to the magnet plunger I01 as shown in Fig. 2.

Winding I04 is shown as being in circuit with a source I05 and a switch I08 (Fig. 3) when the latter occupies a position of engagement with either contact III or contact II2, these being the contacts controlling shunt field coils H6 and I II, respectively, and hence controlling the direction of rotation of the motor I0, whose armature winding is indicated at H5 in Figs. 2 and 3. Thus it will be apparent that the brake will be ineffective so long as current is flowing to the motor windings, but will immediately become effective as the switch I08 is moved away from contact III, and toward contact H2, preparatory to reversal of the direction of rotaion. I' i If the motor is of the series field" type, the circuit will be as shown in Fig. 4.

Even without a reversal of rotation of the motor, the brake IOI, I02 is useful as a means of arresting motor rotation and thus facilitating release, to the jaws 64, 06, of the energy previously stored in the flywheel 22; for, as heretofore noted, any reduction in motor speed immediately produces a corresponding reduction in the speed of gear I 8, and thereby causes the planets to rotate and the jaw 64 to move forward into engine engaging position. Thus energy transfer to the jaws 64, 66 begins as soon as the rotation of motor I0 is retarded; and as such energy transfer may frequently be sufiicient to start the engine even before complete dissipation of the stored energy of the flywheel, there is no necessity, under such conditions, to resort to continued motor operation.

This application is a continuation-in-part.

of my copending application Serial No. 296,681, now Patent No. 2,279,126.

What is claimed is:

1. In an engine starter, the combination of an engine engaging member, a rotatable gear carrying member, means for transmitting the rotation of said gear carrying member to said engine engaging member, means for rendering said rotation transmitting means ineffective during force application to said gear carrying member in one direction, and means for reversing the direction of force application upon said gear carrying member, said last named means including a prime mover and a brake having one element rotatable with said prime mover, and a second non-rotatable element, a switch controlling energization of said prime mover, means responsive to closing of said switch to cause disengagement of said two braking elements, and means responsive to opening of said switch to cause engagement of said two braking elements.

2. In an engine starter, the combination of an engine engaging member, a rotatable flywheel, means for transmitting the rotation of said flywheel to said engine engaging member, means for rendering said rotation transmitting means ineffective during force application to said flywheel in one direction, and means for reversing the direction of force application upon said flywheel, said last named means including a prime mover and a brake having one element rotatable with said prime mover, and a second non-rotatable element, a switch controlling energization of said prime mover, means responsive to closing of said switch to cause disengagement of said two braking elements, and means responsive to opening of said switch to cause engagement of said two braking elements.

3. In an engine starter, the combination of an engine engaging member, a rotatable flywheel, means including an electric motor for storing energy in said flywheel, independently of any rotation of said engine engaging member, and means for subsequently transferring said stored energy to said engine engaging memher, said last-named means including cooperating brake elements for arresting rotation of said energy storing means, and means responsive to engagement of said brake elements to cause release of the stored energy.

' ROMEO M. NARDONE.

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