US1092370A - Electric ignition-generator. - Google Patents

Description

B. LAWRENCE.

ELECTRIC IGNITION GENERATOR.

Q APPLICATION FILED JUNE 3, 1913, 1 092 370 Patented Apr. 7, 1914 4 SHEETS SH EET 1.

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ELECTRIC IGNITION GENERATOR.

APPLICATION FILED JUNE 3, 1913.

Patented Apr. 7, 1914;

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' 1913' Patented Apr. 7 1914 BETH SHEET 3.

B. LAWRENCE.

ELECTRIC IGNITION GENERATOR.

APPLICATlON FILED JUNE 3,1913.

Patented Apr. 7, 1914- I 4 SHEETS-SHEET 4.

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BEN-Infill LAWRENCE, OF LEYTON, ENGLAND,

ELECTRIC IGNITION-GENERATOR Specification of Letters Patent.

Patented Apr. '7, 1914,.

Application. filed June 3, 1913. Serial No. 771,430.

To all whom it may concern:

Be it known that I, BENJAMIN LAWRENCE, a subject of the King of England, residing at Leyton, in the county of Essex, England, have invented certain new and useful Improvements in Electric I nition-Generators, of which the following is a specification.

This invention relates to electric ignition generators which are provided with means for obtaining at certain times an acceleration of the armature, the said means being known as armature tripping devices or starting-trips.

hen it is desired to start an internal combustion engine from rest by turning the engine-shaft, a certain speed must usually be attained before the electric ignition gen erator or, as it is usually termed, the ignition-magneto, will generate a spark to fire the explosive mixture. This turning of the engine-shaft is, especially with large engines, very laborious, and it is therefore desirable that the speed of the ignition-magneto should be accelerated with relation to that of the engine-shaft in order that a spark may be generated while the engineshaft is turning at a speed normally insufficient to produce such a spark. Numerous starting-trip devices have been proposed to attain this desideratum,especially by the insertion'in the drive between the engine-shaft and the ignition'magneto o'f a spring element which is compressed or placed under tension and then tripped to produce a faster speed of the armature than would be ob tained by the direct drive.

It an object of the present invention to produce an improved starting-trip which shall be comparatively cheap and simple to manufacture, shall be composed of a relatively few and strong parts and shall be reliable and simple in its operation. According to the present invention this object is attained by providing an ignition-magneto starting trip having in combination a driving-shaft, a driving-member so mounted thereon as to rotate therewith and also slide along the same, a spring to slide the said member in one direction, a trip con sisting of a cam and cam roll (or its equivalent) to slide it in the opposite direction, a driven-member fixed to the armature-shaft and means operatively connecting the driving and driven members so that the drivenmember always rotates when the drivingmember rotates and also rotates but at a;

greater speed than the driving-member, when the latter is moved endwise by its spring.

It is sometimes desirable, especially with heavy engines, that, if the crankshaft has stopped in the correct position, the engine should be started without being turned by external means, and it is a further object of the present invention to produce an ignition-magneto starting-trip which is capable of producingaa spark adequate to fire the explosive mixture when the engine is at rest, and according to the present invention such means will be provided by making one of the tripping elements movable by external means and independently of the engine shaft to trip thearmature.

These and other features of the invention will be described with reference to the accompanying drawings, and will be pointed out in the claims, but it is to be understood that the invention is not limited to the constructions shown in the drawings.

In the drawings, Figure l is a perspective view of the magneto showing the sleeve through which the armatureshaft is connected to the drivingnnember; Fig. 2 is a perspective view partly in section of the driving-memberwith its spindle and the parts mounted thereon. Fig. 3 is a perspective view of the casing which incloses the driving-member and which is bolted to a part of the framework of the magneto; Fig. 4: is a longitudinal section on the line 4t4 of Fig. 5; Fig. 5 is a crosssection on the line 5-5 of Fig. 4:. Fig. 6 is a cross section on the line 6-6 of Fig. 4. Fig. 7 is a side elevation partly in section of an ignition-magneto provided with a modified form of starting-trip; Fig. 8 is a perspective View of certain of the parts shown in Fig. 7, and Fig. 9 is a side elevation partly in section of a modified form of the device shown in Fig. 7.

The magncto-armature-shaft has fixed to it a sleeve A having formed in it two cam slots A which as shown in Fig. l, are each provided with a part A which lies parallel with the axis of rotation of the shaft. A spindle B'is suitably connected to the engine shaft and carries at one end. an enlargement formed as a cup B to fit over the sleeve A. ing driving-member which takes the form of ;a sleeve C which carries internally two.

feathers C adapted to slide in guide-ways Surrounding the cup is a slid' plunger F B cut in the cup B Fixed in each feather is a pin C carrying a cam-rollC adapted to operate in the cam slots A The sliding sleeve is pressed toward the armature by a spiral spring C which surrounds the sleeve and is located between a rib B on the cup B and a corresponding rib C upon the sliding sleeve, the forward movement ofthe sleeve being limited by a collar B on the end of the cup nearest to the armature. On its outer surface the sleeve G is provided with two cams D each having an operative face D which cams form one element of the trip.

When the sleeve is moved 'endwise against the action of its spring and then released, there would be a hammering between the end of the sleeve and the collar B that limits its forward. movement, and this ham- Inering would ultimately result in damage to the parts. To avoid such hammering a but- 'fer is inserted between the end of the sleeve and the collar, which bufi'er takes the form of a floating collar B surrounding the cup. This floating collar-is pressed away from the collar B by small spiral springs B located in pockets l8 in the side of the collar adja' cent to the sleeve, the movement of the floating collar under action of these springs B being limited by pegs fixed in the outer surface of the cup. In orden that these pegs may not contact with the sleeve C the latter is recessed at C.

spindle instead of bearing directly upon th casing may be supported in ball-loearmgsv which are in turn supported in a recess in the casing.

The casing E is provided with two orifices over which are fixed two cylindrical chan1 bers F in each of which is located a plunger F adapted to be pressed through its orifice into the path of the driving-member cam D by a spring located between the end of the chamber F and the adjacent end of the To limit the motion of the plunger and to prevent it from rotating-it has passing through it a stud F whose ends project at each side and slide in grooves F cut in the walls of the chamber F. One end of the stud F projects completely outside the chamber and carries a roller F- for a purpose to be mentioned.-

Nhen the engine is turned, as for example by cranking, the spindle B is rotated and consequently the cup B" and the sliding" sleeve or driving-member C are also rotated. Durin such rotation the operative faces D of t 1e driving-member cams D will strike the ends of the plunger-s F and since these are stationary the sleeve G will be forced back against the action of its spring C This causes the cam-roll C to move back along the cam slots A so that when the plungers reach the highest point of the cams Dthe cam-rolls will be at the outer end of the cam slots A When the highest point of the cams pass the plungers F the sliding sleeve 0 is moved back rapidly under the action of its spring and the cam-rolls C by reason of the shape of the cam slots A accelerate the speed of the armature sufliciently to cause a spark which will fire the explosive mixture in the ordinary manner. It may be mentioned that normally the camrolls 0 lie in the straight parts A? of the cam slots A and thus provide a direct drive between the engine and the armature. Obviously, this accelerating action upon the armature is not required when the engine is turningsuiliciently fast to produce a spark without such acceleration, andaccordingly, in order that the wear upon the parts may be reduced to a minimum, means are provided for causing cessation of the tripping action by removing one of the tripping memhere from the path of the other.

The outside of the casing is provided with a groove in which is mounted an oscillating setting ring}, G on which are formed two surface cams G adapted to lie underneath and operate upon the rollers F which, as already mentioned, are mounted upon the plungers 1?. These cams G are so shaped that in one position of the setting ring (see Fig. 6)

the plungers Ftare withdrawn {by action of the cams G on. the rollers F) from the path of the driving-member cams I) and in another position (see Fig. of the setting ring the cams G permit the plungers to be moved by their springs into the path of the drivingunemher cams. The first position,

may be called the operative position of the setting ring and the. second its inoperative position.

The setting ring carries an arm G which is connected by a spring G with some stationary part in such a manner that the set- Y ring in such inoperative position a locking device is pr ivided which acts automatically to lock the setting-ring as soon as it reaches the said position. The upper portion of the casing; carries a small rock-shaft Hwhich at one end is provided with a detent H ooaovo required until the engine has attained a certain speed, it is convenient to so design the apparatusv that the look upon the setting ring shall, be automatically released when the engine has attained a speed suflicient of itself to cause proper sparking of the mag- 4 neto. Accordingly the other end of the rock shaft H is provided with a lever H which when the detent H is in looking position, projects approximately radially through the casing E- into close proximity with the surface of the collar B. This collar 13 is provided with two recesses B in each ofwhich located a striker B. "When one of the strikers is in the neighborhood of the lever H, and is stationary it will fall into the bottom of the recess B under the action of gravity. When however, it is rotated centrifugal action will tend to throw it outward until at a certain speed it will project .so beyond the surface of the collar B? that its point will strike the lever H and I will rock the rock shaft H to remove the detent from the notch G Immediately this occurs the spring G will oscillate the setting ring G to remove the plungers F from the path of the cams D. In order that the lever P may be clear of strikers B whenever the setting ring has been retracted into its normal position, another surface cam G is provided upon the setting ring and is so placed that when the detent H is removed from the notch Gthe first movement of the setting ring G will cause the edge of the detent to contact with the lowest point of this cam. As the setting ring moves around to its normal position, the do tent will pass over the surface of the rising cam and .will gradually be moved in a di- -rection to rock the lever H so that the latter is moved into a recess E in the casing and thus is out of range of the strikers B In order that the strikers B and the lever ll may not be damaged should the mechanism he for any reason rotated hackwardlyg their rear surfaces are rounded. Consequently upon such rotation the strikers would on striking the lever H merely be removed down into their recesses.

instead of providing the plungers l with camrol.ls to cooperate with the cams D they provided with flats F to cooperate with the acting surfaces 1) which flats are located parallel. with the said surfaces. The plungers have also further flats F to cooperate with the highest parts of the cams D, these flats being provided to prevent the rounding of the surfaces on either the plungers or the came by reason of a sharp edge upon. one or the other. The ends D of the cams D are slightly undercut in order that when tripped they may be free of the plungers'F and thus cause no wear by reason of contact with the said plunger-s during the rapid forward movement of the sleeve C under action of its spring. These ends D of the cams together with, the corresponding surfaces F of the plungers F are beveled in such a manner that the plungers will readily ride over the cams should the mechanism for any reason be'revolved backwardly, and thus the liability of the parts to damage is greatly decreased.

A n'iodificdform of starting-trip comprising a single mechanism which, at will, openates the said trip either from the engineshaft or from a hand-lever independently of any motion of the engine-shaft, will now be described. As in the previous construction, the magneto-armature shaft has fixed to it a sleeve J provided with cam slots J each of which has a part J parallel with the axis of rotation of the shaft. Avspindle K is suit ably connected to the engine-shaft and cara;

rice at one end a feather K which fits a groove in a sleeve K Thus the sleeve is forced to rotate with the spindle but can slide longitudinally thereon. The sleeve-K is provided with a flange K serving as an abutment for a spring K whose other end rests against the inner face of a coverK pinned at K to the spindle K. Projecting internally from the sleeve K are pins K (or rollers) adapted to coiiperate with the cam slots J Mounted upon an extension of the magneto-frame and surrounding the sleeve J, is an oscillating setting-ring L which is normally held at one end of its movement by a spring. The setting-ring is grooved at L to receive a cord L or the like by means of which it may be partially rotated. Upon a cylindrical. extension L of the setting-ring are out two cam peaks which are reached by faces if. L and are located opposite each other. It will be noticed that the cam faces at L are of slow pitch and have therefore, very little cam action. Upon the rear face if of each cam peak, a small depression provides a shoulder L for a purpose to be explained. .ln order to limit the oscillating motion of the setting-ring L it has formed upon it two shoulders L facing opposite ways, which are adapted to cooperate with a stop if projecting from the frame of the machine. The, arrangement is such that the setting-ring L can be rotated through an angle of 180 or thereabout. A floating cam- 45 ring L carries around the ring M until the extension L Secured to the interior of the cam-ring M are cam-blocks ll/ each of which is provided with a face M of such a width as to fill the depression between the shoulder L and the base L of the cam face D*.' In this Way, the face M constitutes a lock for the cam-ring M under certain circumstances. The cam-ring M is provided near its end remote from the magneto with an internal flange M having two clutch-dogs M which are so placed as to engage with other clutch dogs K when the tripping mechanism is in operation; the clutch-dogs K are formed in the face of the flange K. The floating cam-ring M has a V -shaped flange M upon its exterior'which cooperates with the bent ends of spring blades (one of which is shown dotted in Fig. 7 at L projecting from the magneto-frame. In this way, the floating-ring is normally retained in its inoperative position close to the setting-ring L; when the parts are in this inoperative position, the dogs K and M are not in engagement with each other. A stop ll/ 7 is adapted to contact with one of the spring blades L and so limit the rotation of the cam-ring M.

If the engine has stopped in such a position that there is a compressed charge in one of its cylinders and the crank has moved over the dead-center, the engine may be started from rest without cranking. To do this the driver operates a hand-lever or the like connected with the cord L and causes the setting-ring to move against the action of its spring. If the stop M is not in contact with the spring blade L the floating cam-ring M will be carried around by the cam-face L? until such contact is made and will then be held from further rotation. Thereafter, the cam-faces L as they move around, will cause the cam-blocks M to ride up the faces L of the setting-ring, and so bring the flange M? into contact with the flange K Further rotation of the settingdogs and K engage and lock the sleeve K and cam-ring M together. Continued rotation of the setting-ring L causes the cam-blocks M to ride up the peaks of the setting-ring to force back the sleeve K to compress the spring K Upon further rotation of the setting-ring L the cam-blocks ride over the peak of the cam and the spring K forces the sleeve K rapidly back to its original position, and this movement rotates the armature sufiiciently quickly to give an adequate spark. WVhen it is desired to use this starting-trip by cranking or otherwise rotating the engine-shaft, it can be done in the following manner: The setting-ring L is first rotated suliiciently by the cord L to cause engagement of the clutch-dogs K and M. Then the engine-shaft is turned to rotate the spindle K and therefore, the armstore-shaft. This rotation causes the camblocks M to ride up the stationary camtaces L as in-the previous method of 0 eration, and tripping will he performs as before. It will be seen that the setting-ring L must be re-set after each tripping operation to bring the clutch-dogs K and M into engagement again. Repeated operations by cranking without re-setting of the settingring L may be effected by the employment of a distance-piece such as the pivoted finger L to keep the dogs clutched. Means such as the cam L (Fig. 9) may be provided to withdraw the distance-piece when no further repetitive action is desired. it will be appreciated that it is convenient to provide a definite point at which the tripping movements take place and for this reason the shoulders L and stop L are provided to limit the oscillating movement of the settingding L. The amount of movement allowed for the ring is such that if it.

has to travel a considerable distance before the clutch-dogs K and M are brought into engagement, sufficient further movement will not be available to enable the camblocks M to pass the cam peaks and etlect tripping. Such an occurrence would indicate that the crank shaft was not in the proper position for the explosive mixture to be fired.

The provision of the sloping (instead of merely straight) rear cam-faces L and M enables the period or angle within which the armature may be tripped to be increased so that efiective firing of the explosive mixture may take place even if the crank-shaft is tuted by pivoted pawls 0, the tails of which are forced inwardly by small leafsprings. When the engine reaches a speed which is of itself suflicient to cause adequate sparking the pawls O under centrifugal action turn about their pivots and their noses 0 fall behind shoulders formed near the periphery ofthesliding sleeve K as sc on as the latter is moved forward to compress the trip-spring. As a result, the sleeve will be held outward so that the clutch-dogs Kfand M will fail to engage again and repetitive tripping action will be prevented until the speed of the engine becomes sufliciently slow to allow the noses of the pawls to move upward under action of their springs. Fig. 9

vpossii also illustrates a device for obtaining greater power for the starting trip. A torsion spring P has one of its ends secured to the cover K while the otherend is secured to the sliding sleeve K. The latter, instead of being feathered as formerly, is provided with a spiral feather P which engages with a corto secure by Letters responding spiral groove P in the cover. Thus, as the sliding sleeve K is forced backward by the tripping mechanism, it will also be rotated against the. action of the spring P. Consequently, when the tripping occurs, the sleeve will be forced toward the armature not only by the usual spring K*, but by the torsion spring P and in a spiral direction. In Fig. 9 there is also shown a convenient but well-known method of timing rection, a trip consisting of a cam and camroll to slide it in the opposite direction, a driven-member fixed to the armature-shaft, and means operatively connecting the driving and driven members so that the driven- 'member always rotates when the drivingmember rotates and also rotates but at a greater speed than the driving-member when the latter is moved endwise by its spring.

2. An ignition-magneto starting-trip having in combination a driving-shaft, a driving-member so mounted thereon as to rotate therewith and also slide along the same, a spring to slide the said member in one direction, a trip to slide it in the opposite direction the said trip having one of its members fixed to the said driving-member, a driven-member fixed to the armature-shaft, and means operatively connecting the driving and driven members so that the driven member always rotates when the drivingmember rotates, and also rotates but at a greater speed than the driving member when the latter is moved endwise by its spring.

3. An ignition-magneto starting-trill) having in combination a drivingshaft, adriving-member so mounted thereon as to rotate therewith and also slidealong the same, a spring to slide the said member in one di rection, a cam rigidly secured to the said driving-member, an element to contact with the operative face of the said cam and slide the driving-member in the other direction, means for Withdrawing the said element from the path of the said cam, a drivenmember fixed to the armature-shaft, and means operatively connecting the driving and driven-members so that the driven-- member always rotates when the drivingmember rotates and also rotates but at a greater speed than the driving-member when the latter is moved endwise by its spring.

4. .An ignition-magneto starting-trip having in combination a driving-shaft, a driving-member so mounted thereon as to rotate therewith and also slide along the same, a spring to slide the said member in one direction, a cam rigidly secured to the saiddriving-member, a plunger to contact with the operative face of the said. cam and slide the driving-member in the other direction, a spring and a cam, the one to move the said plunger into the path of the driving-mem-v ber cam and the other to remove it from the said path, a driven-member fixed to the armature-shaft, and means operatively connec'ting the drivingand driv'en-membersso that the driven-member always rotates when the driving-member rotates and also rotates but at a greater speed than the driving-member when the latter is moved endwise by its spring.

5. An ignition-magneto starting-trap having in combination a driving-shaft, a dr1ving-member so mounted thereon as to rotate therewith and also slide along the same, a spring to slide the said member in. one d1rection, a cam rigidly secured to the said dr1ving-member, a plunger to contact with'the operative face of the said cam and sl1 de the driving-member in the other direction, a spring tending to press the plunger mto the path of the driving-member cam, an osc1llating cam normally actuated by a spring to withdraw the plunger from the said path, means to move'the oscillat-in cam into its inoperative position to permit the plunger I to be pressed into operativeposition, a lock operating automatically to lock the oscillating cam in its inoperative position, means operating.automatically at or about a predetermined speed to release the said look, a driven-member fixed to the armature-shaft, and means operatively connecting the drivingand driven-members so that the drivenmember always rotates when the driv1ngmember rotates, and also rotates but at a greater speed than the drivingmember, when the latter is moved endwise by its spring;

6. An ignition-magneto starting-trip having in combination a driving-shaft, a driving-member so mounted thereon as to rotate therewith and also slide along the same, a

ing-member, a casing inclosing the starting-' trip, a plunger mounted on the casing and passing through an orifice therein into the path of the driving-member cam, a sprin tending to ress the plunger into the .sai path, an osclllating setting'ring mounted in a groove in the casing and carrying a'cam to co-act with the plunger, a spring normally acting to move the setting ring to operative position to cause its cam to withdraw the plunger from the path of the driving-member cam, means under the control of the.

driver to move the setting-ring to inoperative position, a detent carried by a rock shaft, a spring acting on the rock-shaft to cause the detent to engage a notch in the setting ring when the letter has been moved to inoperative position, at lever mounted on the rook-shaft and projecting through. the easing into the proximity of a rotating part, a striker located in a recess in the said rotating part and adapted at ire certain speed, to fly out and strike the lever and rock it to release the detent fromv the notch, a driv"en-i-1'1ember fixed to the armature-shaft, and means operatively connecting the driving and driven members so that the driven-member always rotates when the driving-member rotates, and also rotates but at a greater speed, than the driving-member, when the latter is moved endwise by its spring. e

7. An ignition-magneto startingtri'p havoeaszo ing in combination a driving-shaft, a sleeve mounted to rotate therewith and also to slide along the same a spring to slide the sleeve in one direction, a cam rigidly secured to the said sleeve and forming one element of the trip, another element to contact with the operative face of the camand slide thesleeve in the other direction, means for withdrawing the said other element from the path of the sleeve-cam, a driven-member fixed to the armature-shaft, a cam-roll mounted upon the sleeve internally and operating in a camslot in the said driven-member so that the driven-member always rotates when the sleeve rotates, and also rotates, but at a greater speed than the sleeve, when the latter is moved endwiseby it's spring.

in testimony whereof Ihave signed my name to this specification in the presence of two subscribing witnesses.

BENJAMIN LAWRENCE "Witnesses: v

HARRY B. BRIDGE, PERCY HEWITT.

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