US2420407A

US2420407A - High-tension magneto

Info

Publication number: US2420407A
Application number: US535005A
Authority: US
Inventors: Oscar L Bachman
Original assignee: American Bosch Arma Corp
Current assignee: Ambac International Corp
Priority date: 1944-05-10
Filing date: 1944-05-10
Publication date: 1947-05-13
Anticipated expiration: 1964-05-13

Description

May 13, 1947.

Filed May 10, 1944 5 Sheets-Sheet l ffg 2 M W z7- 24 i J7 I 7 fl k 37 7: /i M 1 M! I A)" 5 x/ /Z Z/ J i m A? "Z 2/ J INVENTOR.

Qrrarl Bard/v50 mllll y 1'3, 1947- 0. L. BACHMAN 2 HIGH TENSION MAGNETO Filed May 10, 1944 s Sheets-Sheet 2 if if E u WW I f j 7 INVENTOR.

\ a ascer- A Bar-Am ATTORNEY ilk/l.

May 13, 1947. o. L. BACHMAN 2,420,407

HIGH TENSION MAGNETO' Filed May 10, 1944 a Sheets-Sheet s INVENTOR. arcs/r Z. web/ran ATTORNEY Patented May 13, 1947 UNITED STATES T-ENT OFFICE HIGH-TENSION-MAGNETO Oscar L. Bachman, Springfield,-Mass., assignor to American Bosch Corporation, Springfield,

' Mass, a corporation of New York A'pplicationMay 10, 1944, Serial No. 535,005

(CI. Til- 2059) and replaceable in the housing or outer stator magnetic structure as a unit. The invention also relates to such unitary subassemblies as new articles of manufacture for spare and replacement parts in magnetos of such types, wherein the magneto shaft is'driven at the camshaft speed of the associated engine and drives without speed change the magnetic-rotor and the circuit breaker rotor or camof the magnetmand also the distributor rotor where the magneto is of the multicylinder type.

Heretofore, it wasusual in some-magnetos of timer drive types to support their high tension ignition coils from the housings, or in such other wise that the removal of the coil from the assembled magneto required the prior removal of at least some of the stator parts of the circuit breaker mechanism (as for instance the contact elements with or without their supporting memher or disc) and certain electrical connections thereto, inad-dition to the magnetic rotor, and also the cap or plate and-rotor of the distributor mechanism where provided for multicylinder magnetos. In others of such types, the coil was removable through the bottom of the magneto, after'the magneto was removed from the engine and after its drive or impulse couplingwas disassembled from themagnetic rotor or removed with i.t.- Both of these types of construction resulted in considerable service time in the case'of inspection, adjustment, repair or replacement of the coil, or other electrical part other than the distributor mechanism, and sometimes resulted also in changes in the timing of the magneto on the engine, or in the settin of the breaker mechanism, or in the edge distance of the magneto, which changes were harmful to the continued life and performance of the magneto and engine.

In accordance' 'with .my invention; the unitary subassembly including the high tension ignition coil, the stator parts of the breaker assembly,-and

certain stator magnetic parts supporting them,

as well as the primary and secondary conductors connecting the coil windings with other electrical parts, form a unitary structure which may be removed as a unit from the housing, preferably through the top of the housing so as not to require the disengagement of the magneto from the" engine. Theu'n'it may then bein'spected, re-' 2. paired: or replaced in whole or inpart before it is replaced in the magneto. Thus the time for service is reduced, consequent mistiming, misalinement and misadjustment are rendered less likely,

and if desired the entire-electrical system, except thedistributor mechanism in .the case-of a multicylinder engine, may be replaced at low cost and withoutthe usual long interruption in service upon development of Wear, electrical breakdown or other operational fault in any ofthose electrical and other parts. Since those electrical parts include, as a practical matter, all theweaker elements of-the-magneto most liable to, operative change and. breakdown requiring inspection, adjustment, repair and replacement, this construction provides important advantages in the field of use and particularlyin thoseservices distant from repair stations.

Accordingly, the primary object of myrinvention is to provide in magnetos of timerdrive types, unitary subassemblies of certain electrical and othe normally stationary parts which. are removable from and replaceable in thesmagneto .as a unit, preferably without removing the magmagneto to, reliably support it near its uppe end at aplace longitudinally separated as far as practical froma bearing in the lower end of the outer stator magnetic member. Preferably also, this inner stator magnetic structure is detachably fastened to the outer stator magnetic structure so as to be removabletherefrom and at the same time to stabilize the drive shaft. in its rotation in the assembled magneto, and the high tension 1 conductor connected. to the-secondary winding of thecoil is fastened to the member supporting the stator elements of .the circuit breaker" to reliably secure 'the conductor in place." This unitarysubassembly is especially adapted to a magneto of this kind in which the inner stator magnetic structure has a hollow longitudinal portion through which the drive shaft extends and "around'which the coil is located, and also has at least "one upper andone lower Wing extending radially from'the longitudinal portion' at opposite faces of the coil. Also it is well adapted to such magnetos in which the outer stator magnetic structure or housing has an open top through which the unitary structure may be removed and replaced while the magneto is mechanically connected to the engine, and a bearing near its lower end, particularly in the case of multicylinder types of magnetos in which the distributor cap is detachably fastened over the open end of the housing and has a, main electrode in electrical connection with the distributor rotor and with the high tension conductor leading to the secondary Winding of the ignition coil of the unitary subassembly.

Another object is to provide unitary subassemblies of this kind as new articles of manufacture for use as spare or replacement parts in magnetos of this kind.

Other objects and advantages will appear from the following disclosure of my invention as applied, for example, to several embodiments of four-cylinder magnetos of the timer drive type, taken in conjunction with the accompanying drawings, in which Fig. l is a central vertical section, partly broken away, of one form of magneto within the invention in which the magnet and laminated steel pole shoes therefor are cast in a housing of nonmagnetic material and in which a laminated sleeve is adapted to rotate between the outer and inner stator magnetic structures; Fig. 2 is a plan view of the magneto of Fig. l with the distributor cap and rotor removed to show particularly the circuit breaker mechanism; Fig. 3 is an exploded view, principally in central vertical section, of the magneto, showing, among other things, the unitary subassembly by itself removed from the outer stator magnetic structure; and Fig. 4 is a similar exploded view of another embodiment of a magneto within the invention in which the magnet is fastened to the drive shaft and rotatable with it between the inner and outer stator magnetic structures.

Referring first to the embodiment of Figs. 1-3, the magneto has an outer stator magnetic structure or housing I comprising an aluminum-zinc cylindrically shaped member 2 in which there is cast-in the permanent magnet 3 with laminated pole shoes therefor, and a vertical stack of laminations 4 having a pole shoe. bottom portion 5 of the housing carries a bearing 6 and, if desired, is suitably fastened to a housing and engine flange member I for housing an impulse coupling or ignition timing governor or both, and for fastening the magneto on the multi-cylinder engine with which it is to be associated.

The magneto also has an inner stator magnetic structure 8 which forms a unitary subassembly detachably fastened by screws 9 to the housing I in timed position therein at 9. It comprises a longitudinally extending hollow stack of sheet steel laminations IS with a radially extending wing II at its top and a radially extending wing I2 at its bottom, the bottom wing being held in place by the snap ring I3. Between the upper and lower wings is a high tension ignition coil I l comprising primary winding l5 and secondary winding I5. This coil is located around the portion I l of the inner stator magnetic structure with the wings I I and I2 at the respective upper and lower surfaces of the coil. The upper wing is cast as an insert in the non-magnetic metal member H which forms a supporting member for the circuit breaker stator elements and which serves to locate the inner stator magnetic structure 8 The contracted within the housing I. These circuit breaker stator elements include, as usual, the circuit breaker contacts I8 carried respectively by the pivoted lever i9 and the adjustably stationary support 2!). They also include the condenser 21 which is electrically connected by the conductor 22 to the circuit breaker terminal 23 which also is electrically connected by the low tension conductor 25 to the live terminal of the primary winding i5 of the ignition coil. The inner stator magnetic structure 8 is provided near its upper end with a plain bearing 25.

The drive shaft 26 projects below the magneto, so as to be driven by the internal combustion engine (not shown) at the cam shaft speed thereof. This shaft is reliably supported near its upper and lower ends in the bearings 6 and 25. The circuit breaker cam 2! is detachably fastened on the shaft 26 near the upper end thereof by means of a key and the screw 28 and a washer 29 in operative cooperation with the follower block of the lever I9. To this shaft 26 is also fastened the magnetic rotor 30 comprising laminated sheet steel sleeve portions 3| and 3.2, rotatable as a unit by the shaft in magnetic induc tive relation with the lower wing I2 and the pole shoes of the outer stator magnetic structure.

The outer and inner magnetic structures I and 8 of the magneto are so arranged that in one position the sleeve portions 3| and 32 connect the north pole of the magnet 3 to the lower wing I2 of the longitudinal portion I0, and then, upon rotation, connect that magnet pole to the upper wing I2 through the stack 4, thus reversing the direction of flux through the longitudinal portion Ill and the coil I4 at 90 intervals. In the position shown in Fig. 1, the flux passes from the north pole of magnet 3 to the sleeve portion 3% and thence into and through the lower wing I2, from which it passes into and upwardly through the longitudinal portion I0 and through the upper wing II into the stack 4. From this the pole shoe of the stack passes the flux into the other portion 32 of the sleeve and back to the other pole of magnet 3. At substantially each period of the reversal of the flux in this way, the interrupter contacts l8 are opened by the cam 21 to generate an ignition impulse in the secondary winding I6 in the well known way.

The distributor mechanism of the magneto includes the distributor rotor 33 detachably fastened by friction on the end of the cam 21. It also includes a distributor cap 34 which has sparkplug electrodes 35 electrically connected by wires 36 to the sparkplugs in the cylinders of the engine and sequentially cooperative with the electrode 33 of the distributor rotor. The cap also contains a centrally located main electrode 31 in electrical connection with the electrode 33 of the distributor rotor, and a conductor insert 38 extending into connection with the insulated high tension conductor 39 connected to the terminal of the secondary winding I6 of the ignition coil, so as to conduct the current impulses periodically generated in the secondary winding to the electrode of the distributor rotor for distribution thereby. This high tension conductor 39 is detachably fastened in a notch of the supporting member I! by a strap 40, so as to remain reliably fastened in position as a part of the unitary subassembly.

In order to remove the urutary subassembly 8 from the magneto, the distributor cap 34 is first detached by removing the screws at M, and then the distributor rotor is pulled off the cam extenp the previous embodiment. sembly 49 of this embodiment includes, somewhat for inspection, adjustment, repair or replacement ofanyof the electrical parts including the "coil [4, contact points [8, condenser 2|,and the connections of the' high and flow tension conductors 39, 24'and 22 This inner stator magnetic structure 8, or a new spare or replacement one, may be replaced in the outer stator magj netic structure I, and likewisethe cam and distributor mechanism. Since the removal and replacement is through'the top and/the shaft 25 is driven on its lower projecting end, the magneto need not be removed from the engine for thi's'operation. Also since this replacement with aspare unit isso simple and rapid, without the need for special tools it may be performed in the field by the ordinary engine user.

Now referring to the second embodiment as shown in Fig. 4, the, outer stator magnetic structure 42 comprises the non-magnetic housing portion 43 in which are cast the two stacks of suitably arranged laminations 44 having pole shoes. This structure has an open top, and a contracted bottom portion 45 which carries a plain bearing 45 for the drive shaft 41, and is attached to a housing and engine mounting flange 4 8, as in The unitar subasas before, a hollow longitudinal laminated portion with laminated upper wings 5| and lower wings 52, extending radially at the upper and lower faces of the high tension ignition coil 53. The subassembly is held together by the snap ring 54. This subassembly has a breaker plate for the circuit breaker stator elements 55, said plate being fastened to the laminated structure 50, 5| and having an upper bearing 51 for the drive shaft 41 and an opening for the passage therethrough ofthe insulated high tension coil conductor 59. A rubber grommet holds this conductor reliably in place in the breaker plate. The ignition coil 53 containing primary and secondary windings as before, is located around the longitudinal magnetic portion 55 with its upper and lower surfaces between the upper and lower wings 5!, 52 of the inner stator magnetic structure..

The drive shaft 41 projects below the magneto and is adapted to be driven as before by an internal combustion engine at the cam shaft speed thereof. It is reliably supported in the upper and nets 62. On the upper end of the shaft is keyed the circuit breaker cam 63 detachably, fastened to the shaft by the screw 84 and washer 65. On the upper end of the cam is frictionally held the rotor 66 of the'distributor mechanism, and, as before, the distributor cap 61 is fastened in position over the open end of the housing. When the magneto is assembled, the high tension coil conductor 59 contacts the conductor insert 68 in the distributor cap 61 which extends to the main electrode 69 in contact with the electrode of the distributor rotor 66 for sequential distribution of the ignition impulses generated in the coil 53 to the sparkplug electrodes 19 and wires H.

It will be apparent from the preceding that after removing the distributor cap 61 and rotor 66, and the circuit breaker cam 63, the unitary I subassembly 51 may be removed' as a unit from the magneto for inspection, adjustment, repair and replacement of the electrical parts comprising the ignition coil 53, circuit breaker contacts 55, condenser and the high and low tension conductors electrically connected to the coil and to the main electrode 68 of the distributor "cap and the terminal of the circuit breaker,

From the foregoing as to both embodiments, it

will be apparent that the unitary subassembly,

including the high tension ignition coil, the stator parts of the breaker mechanism and certain stator magnetic parts supporting them, as well as the primary and secondary conductors connecting the coil windings with other electrical parts, form a unitary structure which may be removed from the housing as a unit and which may be inspected, adjusted, repaired, and/or replaced in whole or in part before reassembly in the magneto. These electrical parts constitute the weaker elements of the magneto and those most likely to require adjustment and replacement, particularly the ignition coil, the contact points and the condenser. Thus, as a result of this unitar subassembly, removable from and replaceable in the magneto as a unit, service may be performed in the field of use by an ordinary engine user and without special tools, and without removing the magneto from the engine. In this way, and particularly if the entire subassembly is replaced, an engine, which became inoperative from ignition trouble, may be rendered operative in the minimum time and at low cost,

It is apparent that many modifications may be made in the magnetos herein specifically disclosed without departing from my invention. For instance, the magneto may provide for single cylinder ignition without using any distributor mechanism in which case the high tension coil conductor would be connected directly to the sparkplug of the engine. Or the magneto may provide for ignition of multicylinder engines of other than four cylinders. Furthermore, the magnetic circuit of the magneto may be of any of the well known or other types, whether the magnet or magnets rotate or are stationary, so long as the central longitudinal stack forms a part of the stator magnetic circuit surrounded by the ignition coil to form the core thereof and have the flux therein either reversed or reduced therethrough at the periods of ignition. Also the circuit breaker and distributor mechanism may be of any suitable types so long as the circuit breaker cam and distributor electrode are rotatable with the drive shaft of the magneto. Also the ignition coil may have any suitable construction. These and other changes are intended to be covered by the broad terms of the appended claims.

Having thus described my invention, what I claim is:

1. In a high tension magneto of the timer drive type having an outer stator magnetic structure, a drive shaft, a magnetic rotor fastened to the shaft, and a circuit breaker cam fastened to the shaft; anda unitary subassem'loly which is removable from the drive shaft, the outer stator magnetic structure magnetic housing and re placeable on said drive shaft, in said outer stator magnetic structure and in said magneto housing as a unit and which comprises inner stator magnetic structure, a high tension ignition coil which is supported by the inner stator magnetic structure and which has primary and secondary windings, circuit breaker stator elements supported by the inner stator magnetic structure, a high tension conductor electrically connected to the secondary winding, and a low tension conductor electrically connected to the primary winding and to the stator elements of the circuit breaker.

2. A magneto in accordance with claim 1, in which the inner stator magnetic structure of the unitary subassembly has a bearing for the drive shaft.

3. A magneto in accordance with claim 1, in

which the inner stator magnetic structure of the unitary subassembly is detachably fastened to the outer stator magnetic structure.

4. A magneto in accordance with claim 1, in which the high tension conductor connected to the secondary winding of the coil of the unitary subassembly is fastened to the member supporting the stator elements of the circuit breaker.

5. A magneto in accordance with claim 1, in which the inner stator magnetic structure of the unitary subassembly has a hollow longitudinal portion through which the drive shaft extends and around which the coil is located, at least one upper magnetic wing, and at least one lower magnetic wing, said wings extending radially from the longitudinal portion at the respective upper and lower faces of the coil.

6. In a. high tension magneto of the timer type having an-outer stator magnetic structure with an open top and with a bearing near its lower end, a drive shaft journaled in the bearing and projecting below the outer stator magnetic structure, a magnetic rotor fastened to the shaft, a circuit breaker cam fastened to the shaft near the upper end, and a cap detachably fastened to the outer stator magnetic structure over the open top thereof; and a unitary subassembly which is detaehably fastened to the outer stator magnetic structure and is removable therefrom and replaceable therein as a unit through the open top of the outer stator magnetic structure while the magneto is in operative position on an engine and which comprises an inner stator magnetic structure having an upper bearing for the shaft, a high tension ignition coil which has primary secondary windings and which is supported by the inner stator magnetic structure, circuit breaker stator elements supported by the inner stator magnetic structure, a high tension conductor electrically connected to the secondary winding, and a low tension conductor electrically connected to the primary winding and to the stator elements of the circuit breaker.

In a high tension multicylinder magneto of the timer drive type having an outer stator magetic structure, a drive shaft, a magnetic rotor rastened to the shaft, a circuit breaker cam fastened to the shaft, and distributor mechanism which includes a distributor rotor fastened to the shaft which also includes stationary spark plug electrodes supported by the outer stator magnetic structure in sequential cooperation with the distributor rotor; and a unitary subassembly which is removable from and replaceable in the outer stator magnetic structure as a unit while the magneto is in operative position on an engine and which comprises an inner stator magnetic structure, a high tension ignition coil which has primary and secondary windings and which is supported by the inner stator magnetic structure, circuit breaker stator elements supported by the inner stator magnetic structure, a high tension conductor electrically connected to the secondary winding and to the distributor rotor, and a low tension conductor electrically connected to the primary winding and to the stator elements of the circuit breaker.

8. In a high tension multicylinder magneto of the timer drive type having an outer stator magnetic structure which is open at the top and which has a bearing near its bottom, a drive shaft projecting longitudinally outwardly of the bearing, a magnetic rotor fastened to the shaft, a circuit breaker cam detachably fastened to the shaft near the top thereof, and distributor mechanism which includes a distributor rotor detachably fastened to the shaft and also which includes a distributor cap detachably fastened over the open top of the outer stator magnetic structure with its sparkplug electrodes in sequential cooperation with the distributor rotor and with its main electrode in electrical connection with the distributor rotor; and a unitary subassembly which is removable from and replaceable in the outer stator magnetic structure as a unit through the top thereof while the magneto is in operative position on an engine and which comprises an inner stator magnetic structure having an upper bearing for the shaft, a high tension ignition coil which is supported by the inner stator magnetic structure and which has primary and secondary windings, circuit breaker stator elements fastened to the inner stator magnetic structure, a high tension conductor electrically connected to the secondary winding and to the main electrode of the distributor cap, and a low tension conductor electrically connected to the primary winding and to the stator elements of the circuit breaker.

9. As a new article of manufacture, a unitary subassembly for a high tension magneto of the timer drive type and removable from the magneto housing as a unit through the top thereof while the magneto housing and drive are in operative position on an engine, said subassembly comprising a stator magnetic structure, a high tension ignition coil which is supported by the stator magnetic structure and which has primary and secondary windings, circuit breaker stator elements supported by the statormagnetic structure, a high tension conductor electrically connected to the secondary winding, and a low tension conductor electrically connected to the primary winding and to the stator elements of the circuit breaker, said elements of said subassembly being secured together and said magneto having a removable cap whereby said sub assembly may be removed from the magneto housing or replaced therein as a unit.

10. A new article of manufacture in accordance with claim 9, in which the high tension conductor of the unitary subassembly is fastened to the member supporting the stator elements of the circuit breaker.

OSCAR L. BACHMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PAIANIS Number Name Date 1,613,052 Neighbour Jan. 4, 1927 1,993,825 Bohli Mar. 12, 1935