US2341390A - Circuit making-and-breaking mechanism - Google Patents

Description

Feb. 8, 1944. H. SCOTT 2,341,390

CIRCUIT MAKING AND BREAKING MEcHANIsN lF'iledfMarc1128, 1942 lIN I (EN TOR.

#WORN/SYS Patented Feb. 8, 1944 Al UNITED CIRCUIT lVIAKlNG-AND-BREAKING MECHANISM Lloyd H. Scott, Garden City, N. Y., assignor to Eisemann Corporation, Brooklyn, N. Y., a corporation of Delaware Application March 28, 1942, Serial No. 436,707

v 17 Claims.

This invention relates to circuit making-andbreaking mechanisms and, more particularly, to a make-and-break device adapted to impart a desired timing characteristic to an intermittent current in electrical apparatus, such as in an ignition system for an internal combustion engine.

A general object of the invention is the provision of such mechanism of simple and rugged construction, readily adapted t economical commercial production and which is enicient in operation, relatively free from contact chatter and bouncing and in which contact make may be selectively obtained at any predetermined time regardless of contact wear and substantially instantaneous contact break is had irrespective of the time of contact make.

A more specific object of the invention is the provision in such mechanism of a pair of contact mounting means at least one of which is resilient having a certain recovery characteristic :and the other of which is so driven as to bring the contacts together then deform the resilient mounting means and finally to return the driven means at the rate of travel greater than that of the resilient mounting means upon elastic recovery thereof to obtain substantially instantaneous contact break.

Another object is the provision of such apparatus wherein speed of contact break is substantially the same at various speeds of driven operation of the device.

A further object of the invention is the provision in such mechanism of adjustable stop means whereby desired time of contact make can be had despite contact wear and removal of contact material and without affecting time of contact break.

A further object of the invention is the provision in such mechanism of uid damping means whereby contact chatter and bouncing is substantially eliminated.

An additional object of the invention is the provision of such mechanism characterized by a differential rate of travel of cooperating contact members governing and providing for substantially instantaneous contact break thereby avoiding problems that might otherwise result from breaker and operative mechanism wear.

A still further object is to provide a breaker mechanism applicable to magnetos intended for use on multi-cylinder internal combustion engines of the type used in aviation whereby the breaker device may be operated at an extremely rapid rate, in a manner positively providing makes and breaks with proper timing at all speeds and without the use of heavy spring loading.

Another object is to provide such mechanism readily adapted for dual mounting thereof' for use in dual ignition systems of internal combustion engines and adapted for simultaneousl operation from a common operative means such as a cam thereby simplifying construction of the latter which may of necessity be compensated for use with certain types of engines such as radial engines.

A still further object is the provision of such mechanism whereby substantially instantaneous contact break independent of cam design simplifies the problems thereof particularly where compensated cams must be used and design of one lobe will not of necessity affect that of a successive lobe.

Still another object of the invention is the provision of such structure permitting the employment of certain compensated cam design which is much more accurate in operation than that commonly employed through necessity in prior art structures.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the featuies of Construction, combination of elements and arrangement of parts, which will be exemplied in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. l is a side elevational view with parts in section and broken away showing by Way of example a construction of the present invention in association with an operating cam;

Fig. 2 is a sectional View'. taken on line 2 2 looking in the direction of the arrows;

Fig. 3 is a side elevational view with parts broken away of mechanism shown in Fig. l indicating the relative positions of movable parts just prior to circuit interruption, and

Fig. 4 is a View similar to Fig. 3 showing the movable parts in their relative positions shortly after circuit interruption and prior to complete recovery of some of the movable parts.

In accordance with the present invention a circuit making-and-breaking mechanism is provided which is characterized by resilient contact mounting means having a certain recovery characteristic and which carries one contact member, another contact mounting means carrying a cooperating contact member in spaced relation to the other. Suitable means are provided to move the second contact mounting means toward the resilient contact mounting means first to bring the contacts together on make, then to move the so-driven contact mounting means further in the same direction to deform the resilient contact mounting means and finally to return the driven contact mounting means, if desired substantially to its initial position, at a rate of travel greater than that of the resilient contact mounting means upon elastic recovery. y

Referring to the drawing by way ofexample like numerals refer to like parts throughout. A base member I0, preferably of metal is provided, if desired, with transverse holes I|-|| for bolts which may mount the base member to any suitable supporting structure such as a partition wall between chambers in an encased magneto such as that disclosed in my United States Patent No. 2,286,232, issued June 16, 1942, and which may be suitable for use in the ignition system 'of an internal combustion engine such as an airplane engine which, if desired, may be of the radial type. 'I'he base member Il) may comprise an elongated structure as shown having a channel 2 in the upper face thereof terminating at an end I3 below which a portion may be cut away at I4 to provide clearance for operative mechanism such as a cam I5. A resilient contact mounting means such as a breaker arm structure I6 which may comprise a substantially fiat elongated resilient breaker arm is disposed in the channel I2 with the lower face thereof substantially in contact with the bottom of the channel and the edges thereof having only a few thousandths of an inch clearance with the sides of the channel.

The breaker arm I6 has a free end I'I thereof extending beyond the end of the base I to provide a cam follower portion. If desired a bar I8 constituting a cam follower for cooperation with the cam may be mounted on the free end I1 of the breaker arm. An electrical contact member I9 is mounted upon the breaker arm I6 remote from the fixed end or point of xed mountation and preferably at or near the free end Il or cam follower I8 as shown.

A saddle or spacer member preferably of insulating material is located upon breaker arm I6 and may be of such dimension as to be received in the channel I2 as shown.

An elongated substantially flat adjustable stop plate 2| has one end thereof for xed mountation disposed upon the saddle 20 and a free end 22 thereof extends outwardly for engagement by a suitably adjustable stop means hereinafter described. In the vicinity of the end 22 of the plate 2| a hole 23 is formed therein through which an electrical contact member 24 adapted for cooperation with contact member I9 freely reaches. The contact member 24 is suitably mounted upon another resilient breaker arm structure such as an elongated substantially flat resilient breaker arm 25 having a mounting end remote from the contact 24 resting upon the plate 2| with their opposed faces, which may comprise plane surfaces of substantial area, disposed closely adjacent each other.

A cap plate 26 has a footing portion 21 seating upon the breaker arm 25, an end 28 having an internally threaded bore 29 for threaded reception of a circuit terminal and an extending arm 30 through the free end 3| of which is provided an internally threaded bore which threadably engages an externally threaded shank 32 of an adjustable screw having a stop o1' abutment head 33 engaging beneath the free end 22 of the plate 2| as shown so that the position of the Contact member 24 relative to contact member I9 may be adjusted at will for predetermining the time of contact make. A lock nut 34 is threadably engaged upon the shank 32 to lock the adjustment screw in any desired adjusted position.

The footing 2l of the cap plate 25 has internally threaded holes 35-35 therein in which are anchored threaded ends of bolts 35-35 extending through holes in a plate 3l, preferably of insulating material and located beneath the base |0, up through holes in the base, the breaker arm IB, saddle or spacer member 2i), the plate 2| and breaker arm 25, preferably With sleeves 38-38 of insulating material interposed between the shanks of the bolts .3G-36 and the walls of the holes in the base I and breaker arm I6. Thus `the contact member 24, breaker arm 25, plate 2|, cap plate 25, and adjustable abutment 33 are kall insulated from the base I ll, breaker arm 6 and contact member I9.

The device as described is adapted for mountation in any suitable fluid damping medium such as dielectric transformer oil or dielectric gaseous fluid for'example air, carbon dioxide, nitrogen, etc. Accordingly When the breaker arms 'l5 and 25 are deformed or flexed respectively away from the base I0 and plate 2|, bodies of damping fluid will be interposed therebetween for absorption of kinetic energy to avoid contact chatter andbounclng.

The breaker arm 25 is of such construction and so related to its fluid damping means as to have a certain recovery characteristic and to be capable of a certain rate of travel upon velastic recovery when released from a deformed or flexed position. The breaker arm I6 is so constructed and related to its fluid .damping means as to have a faster recovery characteristic, that is to be capable of a rate of travel greater than that of the breaker arm 25 upon elastic recovery when released from a deformed or flexed position. In the structure shown this is attained by making the breaker arm 25 of greater iiexibility than the breaker arm I6 such as by making it thinner and accordingly for eiiiciency of damping the breaker arm I 5 is located in the channel I2 which provides with the breaker arm I6 an entrapping space oriced at the end of the base to obtain effective cushioning sufcient to eliminate bouncing, while breaker arm 25 merely requires the adjacent location of a substantially fiat plate 2| for a similar purpose.

En Fig. 4 is shown by way of example the relative positions of the contact members I5 and 24 and their breaker arm supports I 6 and 25 when a lobe I5I of the cam I5 has moved in cooperation with the follower I8 to iiex or deform the breaker arms I5 and 25 to the iiexed or deformed positions shown. The relative positions of the parts indicated in Fig. 4 are those just prior to contact break. Upon further rotation of the cam I5 the follower I 8 slips off the high portion of the lobe I 5| to permit the flexed or deformed breaker arms I6 and 25 to return to their initial positions for repetition of the cycle. In Fig. 5 the relative positions of the parts are shown at an instant after contact break and as the breaker arms are moving toward their initial or rest positions with the breaker arm 25 traveling at a slower rate of speed than breaker arm I 6. The.

circuit was broken, that is the contact members i9 and 24 separated almost instantaneously when the cam follower 5B slipped off of the cam lobe 51 and the breaker arm i5 started traveling to its initial or rest position at a speed faster than the travel of the breaker arm 25.

Although preferred obviously the structure need not be mounted in the position depicted since it will operate eiciently in a reversed position (i. e., bottom side up), in a horizontal position wherein the breaker arms are mounted side by side, etc., that is in any desired position in free space, the mass of moving parts being so small and the construction such as to be substantially free in operation from interference by force of gravity.

The circuit making-and-breaking device of the invention is adapted to make and break an electrical circuit such as that of a magneto in an ignition system of internal combustion engines such, for example, as those adapted for airplane service. lin a dual ignition system, a pair of units of the present invention may be mounted in side-by-side relation so as to be operated simultaneously by a single cam, an important feature in radial engines wherein the cam must be carefully compensated in view of the fact that only one master connecting rod is connected to a crank arm on the crank shaft and all of the other connecting rods are connected to the former.

`From the preceding description of a typical form of device embodying the invention, it will be seen that the objects set forth above are erliciently attained and since certain changes may be made in the above construction and different embodiments of the invention could be made Without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawshall be interpreted as illustrative and not in a. limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specic features of the invention. herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, What l claim as new anddesire to secure by Letters Patent is:

l. In a circuit making-and-breaking mechanism. the combination comprising, resilient contact mounting means having a certain recovery characteristic, a contact member mounted thereop., a driven contact mounting means, a cooperating contact member mounted on the latter in spaced relation to the other contact member, and means to move said driven mounting mea-ns in one direction to bring the contact members togather and deform said resilient mounting means and finally to return said driven mounting means at a rate of travel greater than that of said resilient mounting means during elastic recovery.

In a circuit making-and-breaking mecha.- nism, the combination comprising, resilient contact mounting means having a certain recovery characteristic, a contact member mounted thereon, a driven resilient contact mounting means having a faster recovery characteristic, a cooperating contact member mounted on the latter in relation to the other contact member, and means to engage and move said driven mounting means in one direction to bring the contact members together and then deform both mounting means and to disengage said driven mounting means to release it for return to its initial position at a rate of travel greater than that of said nrst mounting means during elastic recovery.

3. In a circuit making-and-breaking mechanism, the combination comprising, a resilient breaker arm structure having a certain recovery characteristic, a contact member mounted thereon, a driven resilient breaker arm structure having a faster recovery characteristic, a cooperating contact member mounted on the latter in spaced relation to the other Contact member, and means to engage and move said driven breaker arm structure in one direction to bring the contact members together and then deform both said breaker arm structures and to disengage said driven breaker arm structure to release it for return to its initial position at a rate of travel greater than that of said first breaker arm structure upon elastic recovery.

e. ln a circuit making-and-breaking mechanism, the combination comprising, a resilient breaker arm structure having a certain recovery characteristic, a contact member mounted thereon, a driven resilient breaker arm structure having a faster recovery characteristic, a cooperating contact member mounted on the latter in spaced relation to the other contact member, stop means limiting movement of said rst breaker arm structure toward said driven breaker arm structure to predetermine position of make,

means to engage and move said driven breaker arm structure in the direction toward said irst breaker arm structure to bring the contact memers together and then deform both said breaker arm structures and to disengage said driven breaker arm structure to release it for return to its initial position at a rate of travel greater than that of said first breaker arm structure during elastic recovery.

5. In a circuit making-and-breaking mecha-- nism, the combination comprising, a resilient breaker' arm structure having a certain recovery characteristic, a contact member mounted thereon, a driven resilient breaker arm structure hava faster recovery characteristic, a cooperating contact member mounted on the latter in spaced relation to the other contact member, adjustable stop means limiting movement of said first breaker arm structure toward said driven breaker arm structure to predetermine .position of make, and means to engage and move said driv 'i breaker arm structure in the direction tou/'ard said nrst breaker arm structure to bring the Contact members together and then deform both said breaker arm structures and to disengage said driven breaker arm structure to release it for return to its initial position at a rate oi travel greater than that of said rst breaker arm structure during elastic recovery with the contact members being separated at a time determined by the dierential in rates of travel on recovery irrespective of said stop means.

5. In a circuit making-and-breaking mechanism, the combination comprising, a pair of substantially parallel resilient breaker arms each xediy mounted at one end in spaced apart relation to the other, a pair of spaced apart cooperating contact members each carried by one of said arms remote from the mounting end thereof, one of said arms being adapted to be driven and capable of a faster rate of travel on elastic recovery than the other, and means to engage the driven arm and move it adjacent its Contact member' in the direction toward the other arm to cause the Contact members to make and then deform both arms for a predetermined period of make, said means being adapted to disengage said driven arm to release botharms for return to their initial positions causing substantially instantaneous contact break upon such movement.

'7. In a circuit making-and-breaking mechanism, the combination comprising, resilient contactmounting means having a certain recovery characteristic, a contact member mounted thereon, another contact mounting means, a cooperating contact member mounted on the latter in spaced relation to the other contact member, means to move said second mounting means in one direction to bring the contact members together and deform said resilient mount and finally to return said second mounting means at a rate of travel greater than that of said resilient mounting means upon elastic recovery, and fluid damping means for said resilient mounting means to absorb kinetic energy thereof.

8. In a circuit making-and-breaking mechanism, the combination comprising, resilient contact mounting means having a certain recovery characteristic, a contact member mounted thereon, second resilient contact mounting means having a faster recovery characteristic, a cooperating contact member mounted on the latter in spaced relation to the other contact member, means to engage and move said second mounting means in one direction to bring the contact members together and then deform both mounting means and to disengage said second mounting means to release it ysubstantially to its initial position to which it moves at a rate of travel greater than that of said first mounting means upon elastic recovery, and fluid damping means for said rst resilient mounting means to absorb kinetic energy thereof.

9. In a circuit making-and-breaking mechanism, the combination comprising, resilient contact mounting means having a certain recovery characteristic, a contact member mounted thereon, second' resilient contact mounting means having a faster recovery characteristic, a cooperating contact member mounted on the latter in spaced relation to the other contact member, means to engage and move said second mounting means in one direction to bring the contact members together and then deiorrn both mounting means and to disengage said second mounting means to release it substantially to its initial position to which it moves at a rate of travel greater than that of said rst mounting means upon elastic recovery, and uid damping means associated with each of said resilient mounting means to absorb kinetic energy thereof.

10. In a circuit making-and-breaking mechanism, the combinationv comprising, a resilient breaker arm structure mounted at one point carrying a contact member remote from that point and having a certain recovery characteristic, contact mounting means carrying a second contact member in spaced relation to the Iirst and for cooperation therewith, means to move said mounting means in one direction to bring the contact members together and deform said breaker arm structure and finally to return said mounting means at a rate of travel greater than that of saidbreaker arm structure upon elastic recovery, and fluid damping means for said breaker arm structure comprising a structure disposed closely adjacent thereto for interpositioning of a body of damping fluid upon elastic recovery of said breaker arm structure.

1l. In a circuitmaking-and-breaking mechanism, the combination comprising, a resilient breaker arm structure mounted at one point carrying a contact member remote from that point and having a certain recovery characteristic, contact mounting means carrying a second contact member in spaced relation to the iirst and for cooperation therewith, means to move said mounting means in one direction to bring the Contact members together and deform said breaker arm structure and nally to return said mounting means at a rate of travel greater than that of said breaker arm structure upon elastic recovery, and uid damping means for said breaker arm structure comprising a structure having a plane surface disposed closely adjacent a plane surface of said breaker arm structure for interpositioning of a body of damping iuid upon elastic recovery of the latter.

l2. In a circuit making-and-breaking mechanism, the combination comprising, an elongated substantially flat resilient breaker arm mounted at one end carrying a contact member remote from that end and having a certain recovery characteristic, contact mounting means carrying a second contact member in spaced relation to the rst and for cooperation therewith, means to move said mounting means in one direction to bring the contact members together and deform said breaker arm and finally to return said mounting means at a rate of travel greater than that of said breaker arm upon elastic recovery, and fluid damping means for said breaker arm structure comprising a structure having an extended substantially at surface in relatively iixed position adjacent a substantially at surface of said breaker arm when in its make position with both disposed in a body of dielectric damping uid.

13. In a circuit making-and-breaking mechanism, the combination comprising, an elongated substantially flat resilient breaker arm mounted at one end carrying a contact member adjacent a free end thereof and having a certain recovery characteristic, Contact mounting means carrying a second contact member in spaced relation to the first and for cooperation therewith, means to move said mounting means in one direction to bring the contact members together and deform said breaker arm and nally to return said mounting means at a rate of travel greater than that of said breaker arm upon elastic recovery, an elongated substantially flat plate xedly mounted at one end with the xedly mounted end of said breaker arm and extending in substantial contact along the latter and terminating in an adjustable end beyond the free end of said breaker arm, said plate and said breaker arm being mounted in a body of gaseous dielectric damping uid, whereby iiuid between said plate and said arm damps the return of said arm toward said plate, and adjustable means engaging said plate adjustable end to predetermine position of make.

14. In a circuit making-and-breaking mechanism, the combinati-on comprising, a pair of substantially parallel resilient breaker arms each xedly mounted at one end in spaced apart relation to the other, a pair of spaced apart cooperating contact members each carried by one of said arms remote from the mounting end thereof, one of said arms being adapted to be driven and capable of a faster rate of travel on elastic recovery than the other, means to engage the driven arm and move it adjacent its contact member in the direction toward the other arm to cause the contact members to make and then deform both arms for a predetermined period of make, said means being adapted to disengage said driven arm to release both arms substantially to their initial positions causing substantially instantaneous contact break upon such recovery movement, and fluid damping means for each of said breaker arms each comprising a structure disposed closely adjacent the breaker arm With Which it is associated for interpositioning of a body 0f damping fluid upon elastic recovery of said breaker arms.

15. In a circuit making-and-breaking mechanism, the combination comprising, a pair of substantially parallel resilient breaker arms each fixedly mounted at one end in spaced apart relation to the other, a pair of spaced `apart cooperating contact members each carried by one of said arms remote from the mounting end thereof, one of said arms being adapted to be driven and capable of a faster rate of travel on elastic recovery than the other, means to engage the driven arm and move it adjacent its contact member in the direction toward the other arm to cause the contact members to make and then deform both arms for a predetermined period of make, said means being adapted to disengage said driven arm to release both arms substantially to their initial positions causing substantially instantaneous contact break upon such recovery movement, and fluid damping means for each of said breaker arms each comprising a structure disposed closely adjacent the breaker arm with which it is associated for interpositioning of a body of damping iiuid upon elastic recovery of said breaker arms, said breaker arms and damping structures being mounted in a body of dielectric damping fluid,

and said damping structure for said driven breaker arm comprising a relatively Xed channeled member in the channel of which said arm seats in its initial position.

16. In a circuitl making-and-breaking mechanism, the combination comprising, a pair of substantially parallel resilient breaker arms each xedly mounted at one end in spaced apart relation to the other, a pair of spaced apart cooperating contact members each carried by one of said arms remote from the mounting end thereof, one of said arms being adapted to be driven and capable of a faster rate of travel on elastic recovery than the other, means to engage the driven arm and move it adjacent its contact member in the direction toward the other arm to cause the contact members to make and then deform both arms for a predetermined period of make, said means being adapted to disengage said driven arm to release both arms substantially to their initial positions causing substantially instantaneous contact break upon such recovery movement, and fluid damping means for each of said breaker arms each comprising a structure disposed closely adjacent the breaker arm with which it is associated for interpositioning of a body of damping fluid upon elastic recovery of said breaker arms, said breaker arms and damping structures bein-g mounted in a body of dielectric damping fluid, and said damping structure for said driven breaker arm comprising an elongated relatively fixed channeled member in the channel of which the major portion of said arm in its initial position seats with a few thousandths of an inch clearance and with the end thereof projecting beyond the channeled member for driven engagement.

17. In a circuit making-and-breaking mechanism, the combination comprising, a pair cf resilient contact mounting breaker arm structures with one having a faster recovery characteristic than the other, a pair of cooperative Contact members with one mounted on one of said breaker arm structures and the other mounted on the other breaker arm structure, and means to engage the breaker arm structure having the faster recovery characteristic for moving said pair of breaker arm structures to deformed positions and then to disengage that breaker arm structure t0 release both breaker arm structures for return at diiferent rates of travel to their initial positions thereby quickly separating said contact members.

LLOYD H. SCOTT.

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