US1307342A - Igniter - Google Patents

Description

P. BROWN.

IGNITER.'

APPLICATION FILED oc. 2. ma,

Patented June 241, l

A 1 ,.Cl/Aq ATTORNEYS.

UNITED STATESl PATENT OFFICE.

PHELPS BROWN, 0F SPRINGFIELD, MASSACHUSETTS.

IGNITER.

Specification of Letters Patent.

Patented June 24, 1919.

Application fued october 2, 191s. serial No. 256,615.

ments in Igniters, of which the following is a specification.

This invention relates to igniters and more particularly to igniters of the reciprocatory armature type.

Igniters of this general type possess many important and now well recognized advantages, but heretofore their field of service has been somewhat restricted by reason of their noisiness in operation. According to one example of prior practice, the igniter is so constructed that flux from a source of magnetism may be rst directed through the cores of a generating winding and then shunted or excluded from said cores. Heretofore, two armatures, each reciprocable to and from the cores, have been provided for this purpose and one armature,

by engagement with the cores at one end, is arranged to complete a magnetic circuit therethrough from the source of magnetism, while the other armature, by engagement with the cores at the other end, shunts the flux and excludes it from the cores. The armatures are also commonly moved at very high speed in one direction and it follows that that armature, `which engages the cores on the high speed stroke, must necessarily be arrested very suddenly and the impingement of such armature with the cores produces a great deal of noise. This invention is concerned, among other things, with the elimination of one armature, (the one which is notoriously noisy in operation) and, by such elimination, not only is the operation of the igniter made more quiet, but a very substantial reduction in the weight of the moving parts is accomplished, as well as other advantages as will later appear.

The invention has for its object to provide an igniter, wherein an armature is provided to cooperate with the core of a generating coil and by movement to and from such core, to establish and interrupt a magnetic circuit from a suitable source of magnetism through such core, together with means including a permanent air gap to provide a shunt path for the iuX from said source when the armature is moved away from the COTS.

According to this feature of the invention, a permanent shunt path is provided across the poles of the source of magnetic flux, but such path by reason of the permanent air gap is of higher reluctance than the magnetic path through the core and armature, when these latter elements are in engagement, and of less reluctance than the latter path, when the last-named elements are separated by an air gap. Thus, with the armature in engagement with the core, thc` major portion of the flux is directed through the latter while, when the armature is separated from the core, the major portion of the flux traverses the permanent shunt path, and the permanent air gap therein, to'assist in the diversion of the iiuX from the core.

Other objects and advantages will appear in the following description and in the illustrative embodiment of the invention in the accompanying drawings, in which:

Figure l is a top plan view of an igniter embodying the invention;

Fig. 2 is an elevational View thereof with certain parts broken away;

Fig. 3 is a cross-sectional view taken on the line 3 3 of Fig. l; and

Fig. t is adiagrammatical view illustrati've of the electrical connections of the igniter.

Referring to these drawings: The igniter includes essentially a suitable source of magnetic flux, as a permanent magnet 6; a suitable generating winding, as the coil 7; a core, as 8, with which an armature, as 9, cooperates to alternately establish and interrupt a magnetic circuit from the source 6 through the core 8 and generating winding 7; and means providing a shunt path across the poles of the magnetic source, as the magnetic conductors lO'and' 1l, which are separated by a permanent and relatively small air gap l2.

The essential elements of the invention, as thus briefly described, may be varied in many particulars and still embody the invention and the following specific descrip. tion of these essential elements is to be taken as merely illustrative. In addition to the elements described there may be, and preferably are, provided other elements, as will appear, to the end that the igniter may be made more efficient for its intended use. The following description is, therefore, to be considered merely as an illustrative eX- ample of one suitable form of igniter, in`

which the invention may be embodied, and it is recognized` that the` illustrated structure may be varied in numerous ways and still,

intermediary element 13 between the source 6 andy armature. Such intermediary element is not necesarily essential for all pur'- poses, butis generally to be preferred and is here provided in the shape of a second core on which a second generatingv coil 14 may be mounted to increase the efliciency of the ig'- niter.

Each core may advantageously be com binedwith the adjacent magnetic conductor, already described as forming an element of the shun-t path. Thus, the members 8 and 10 may be made up in oneelbow shaped unit, as shown, and the members 11 and 13 may be made up in a similar manner. Preferably, as indicated in Fig. 1, the elements 8, 10, 11 and 13 are built up of a plurality of soft iron laminations in the usual and well known manner.

The source of magnetic flux may advantageously consist of one or more permanent bar magnets 6. As sho-wn, two magnets 6 are provided, one on each side of the cores, although obviously a greater or less number of magnets may be used, as desired. One pole of each magnet, as the north magnetic pole, is magnetically connected to the core 8 andto the shunt forming extension 10 and the other pole of each is magnetically connected to the core 13 and to the shunt form ing extension 11. This connection of the magnets, cores and extensions may be accomplished in any suitable manner. For example, two angle shaped blocks 15 may be provided, as shown in Fig. 1, to partially encompass the laminations of the combined members 8 and 10 and ya like arrangement may be provided for the combined members 11 and 13. The magnets 6 then bridge across and connect each pair of blocks 15 and the entire' assembly described may be held together by suitable means, as retaining bolts 16. Y

v To mechanically, but not magnetically, connect the lower ends of coresS and 13, two cross-bars -17 of non-magnetic material are provided and such cross-bars may be mounted on and secured to the cores in a maimer similar to that in which the ma ets 6 are mounted and secured. The bars 1 and thus the entire assembly described, are supported froma suitable frame A through the intermediary of a pair of brackets 18 and a plate 19. The latter is offset downwardly intermediate its ends to clear the armature 9 and afford -a seat for a spring 20, which, as shown, tends to hold the armature against the lower ends of cores 8 and 13.

The spring 2O constitutes the means for moving" armature 9 toward t-he cores 8 and 13. Y Any suitable means may be provided to disengage the armature 9 from the cores and move it in the opposite direction. For example, a bar 21, having a forked lower lend to straddle arn'iature 9, is slidably mounted in and between the cross-bars 17. A spring 22, interposed between the upper end of bar 21 and a block 23, of non-magnetic' material held between the magnets 6, tends to move bar 21 downwardly. The bar 21 may be raised by a cam 24 fixed on a shaft 25 rotatably mounted in casing A. Shaft 25 may be driven at any desired speed in the illustrated direction by means with which the present invention is not concerned. As shown in Fig. 3, the eXtreme lower' end of bar 21 rides upon the periphery of cam 24 and therefore will be gradually raised thereby, thus allowing the armature 9 to 'be moved upwardly into engagement with the cores 8 and 13 under the force of spring 20. The cam 24 is preferably arranged to lift bar 21 a farther distance to permit the separation of its armature engaging portion from the arm a-ture, thus compressing spring 22. Cam 24 is also so constructed as to periodically allow bar 21 to drop andV be suddenly moved downwardly under its weight and the force of spring 22 to forcibly dislodge the armature 9 from the cores S and 13, to which it is, of course, magnetically held. The downward movementofbar 21 is sufficient to separate the armature9 from the cores8 and 13 by an air gap greater than the air gap 12 existing between the adjacent ends of the shunt forming extensions 10 and 11.

Tf desired, in addition to the main or primary generating winding (comprising the coils 7 and 14), there may be provided a secondary winding` comprising coils 26 and 27 superimposed upon the coils and 14 respectively. Tf secondary coils are used, the primary winding should, as shown in Fig. 4, be arranged in a closed circuit which should be interrupted .periodically to induce an electro-motive force in the secondary winding. Thus, the primary coils 7 and 14, which are suitably connected together (as in series by the wire 28), have their terminal wires 29 and 30 electrically connected tothe breaker points 31 and 32, respectively, of aninterrupter. Preferably, as is usual, a condenser 33 is bridged acrossV the breaker points131 and 32. The secondarycoils are alsoV suit-Y ably connected together (as in series by a wire 34), and the terminals of the secondary winding are represented by'' and 36 one (as 36) being preferably grounded. to conform to the general practice. As shown in Fig. 2, one breaker point, as 32, is adjustably secured to and insulated from base A and the other 'breaker point, as 31, is carried on the end of one arm of a bell crank lever 3S pivoted at 39 to frame A. A suit-'able spring Ll() tends to hold the breaker points 31 and 32 in contact and they are automatically separable during the downward flight or' armature 9, by the engagement ot the other arm of the lever 38 with a projection 42 (Fig. 3) on armature 9.

In operation, as shaft 25 revolves, cam 241 periodically raises bar 21, as described, and thus allows the armature 9 to be moved upwardly into engagement with the lower ends of cores 8 and 13. The armature, at such time, magnetically connects the core ends and a magnetic circuit from the magnets G through both cores and the armature results. This circuit is obviously of lower reluctance than the shunt circuit for the magnets, which shunt circuit includes the extensions 10 and 11 and the permanent air gap 12. Therefore, the major portion of the flux from magnets 6 will encircle the primary generating winding. It has been described lthat the cam 211 subsequently releases bar 21 and allows it to be rapidly moved dowir wardly to forcibly dislodge the armature 9 from the core ends and thereby interrupt the magnetic circuit theretofore existing through the cores. As is well known, upon interruption of a magnetic circuit, there is not the immediate cessation of flux in the circuit that might be desired in order to produce the maximum change of flux in the generating windings, and thus the generation of the maximum electro-motive force therein. The lines of force tend to jump the air gap and it is known that such tendency results in a rapid weakening of the magnets. It is to prevent such rapid deterioration of the magnets and also to divert the lux as soon as possible from the cores, that the shunt path is provided for the magnets during that period when the armature is 'separated from the cores.

This shunting of the flux is, according to this invention, accomplished by means which include a permanent air gap, as 12, as distinguished from a movable magnetic member which periodically bridges the poles of the magnets and shunts the flux therefrom. Thus, as soon as the armature 9 has been separated from the core ends a distance equal to half the length of air gap 12, the reluctance of the shunt path (including parts 10, 11, and 12) is at least no greater than that of 'the path which includes the cores S and 14, the armature 9, and the double air gap between the armature and cores. As the armature 9 continues to move farther away from the core ends, the reluctance of the magnetic circuit through the generating winding increases very rapidly and the major portion of the flux then traverses the shunt path and is diverted from the cores. Practically, since armature 9 in its downward light moves at high speed, there is produced a rapid change of flux in cores 8 and 1st and thus a current is generated in the primary winding.

It the secondary winding is used, (and it may be used to advantage although not necessary to the invention) the current generated in the primary winding flows in a closed path, as described, and, substantially at 'the time when maximum current exists in the primary winding, the breaker points 31 and 32 are separated by the downward Hight of armature 9, whereby the normally closed circuit is interrupted and an electro -motive iorce is induced in the secondary winding.

The invention is particularly character'- ized by the provision of means affording, for the magnetic source, a shunt path of substantially constant reluctance and of a reluctance greater than that of the magnetic circuit through the generating winding, when the armature engages the cores, and less than that of the last-named magnetic circuit, when the armature is moved away from the cores. By this means, a diversion of the flux from the generating windings is obtained upon interruption of the magnetic circuit theretofore encircling such windings. Moreover, and this is most important, I obtain this desirable result without requiring a movable magnetic member, as a second armature, which engages and connects the upper ends of the cores at substantially the time that the armature 9 is disengaged from the lower ends of the cores. The elimination of such second armature results in the elimination of much of the noise in operation which has heretofore characterized igniters of this type for, obviously, the impingement of a fast traveling metallic member on stationary metallic members contributes largely to the production of noise, much more so indeed than the impingement of bar 21 on armature 9, for the latter is yieldably supported and cushioned against the blow. Moreover, the armature engaging portion of bar 21 need not be metallic.

The elimination of the second armature also results in a marked reduction in the weight of moving parts, which is important not only as to economy of material, but more particularly as to its effect on high speed operation. Large and relatively heavy moving bodies necessarily interfere by reason of their weight and inertia with the desired high speed operation.

Certain features of this invention are shown but not claimed in a copending application Serial No. 259,530, filed October 211, 1918. Y

The invention has been disclosed herein in a single form for illustrative purposes, but many other forms and arrangements will readily suggest Vthemselves to those skilled in the art, having for their obj ect the use of the invention in a specific formy difering from the one disclosed. It is, therefore, desired to have the scope ofthe invention determined by the appended claims interpreted in the spirit of the disclosure rather than in the letter of the exact form disclosed. Y

lVhat I claim is- 1. In an igniter, a source of magnetic flux, means including cooperating and relatively movable members to provide a magnetic circuit lof varying reluctance from said source, a generating winding associated with one of said members, and means at all times providing a second magnetic path of constant reluctance for the flux from said source, the reluctance of the second path being greater than the minimum and less than the maximum reluctance of said circuit.

2. An ig'niter, comprising, a source of magnetic iux, means including a core and cooperating armature to provide a magnetic circuit from said source, a generating winding associated with said core, means to move the armature away from said core to decopies of this. patent may be obtained for crease the flux through the core and winding, and means at alltimes providing a shunt path for the flux from said source, said means including a relatively small permanent air gap and affording a shunt path of constant reluctance. v

3. YVAn igniter, comprising, a source of magnetic flux, a generating winding, a core for the latter having one end magnetically connected to one magnetic pole of said source, an armature movable toward and away from said coreV to magnetically connect and disconnect the latter to and from the other magnetic pole of said source, and means permanently and magnetically Vconnecting the poles of said source yexcept for an air gap of less length than the maximum ,air gap between said core and armature.

4. In an igniter, two magnetic conductors separated at one end by a relatively small air gap and at the other end by a relatively large distance, an Varmature to alternately connect and disconnect the last-named Vends of said conductors, a source of magnetic iux connecting said conductors intermediate their ends, and generating coils on said conductors between said source and the lastnamed ends of the conductors.

PHELPS BROWN.

five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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