US2027692A

US2027692A - Method of obtaining advanced and retarded ignition

Info

Publication number: US2027692A
Application number: US722980A
Authority: US
Inventors: Klaiber Erich
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch AG; Robert Bosch GmbH
Priority date: 1933-06-24
Filing date: 1934-04-28
Publication date: 1936-01-14
Anticipated expiration: 1953-01-14

Description

Jam-14, 1936. E. KLAIBER' 2,027,692

METHOD OF OBTAINING ADVANCED AND RETARDED .IGNITION FiIed A ri 28, 1954 nun A A A Patented Jan. 14, 1936 PATENT OFFIE METHOD or OBTAINING ADVANCED AND nnrannnn IGNITION Erich Klaiber, Stuttgart, Germany,

Robert Bosch Aktiengesellschaft,

Germany assignor to Stuttgart,

Application April as, 1934, Serial No. 322,980

In G

'1 Claims.

This invention relates to methods of and means for obtaining advanced and retarded ignition with a magneto having per rotation at least two periods of fiux change capable of providing ignition voltages in the generating windmg.

One object is to utilize certain of such periods of flux change, for producing advanced ignition and certain other of such periods for producing retarded ignition, whereby, if desired, both advanced and retarded ignition, instead of one alone, may occur at periods of substantially the maximum time rate of change of the magnetic flux in the generatingwinding of the magneto.

Another object is to provide in such a magneto interrupting mechanism for interrupting the circuit of the generating winding at the utilized periods of flux change, and preferably to provide one interrupting mechanism set for advanced ignition and another interrupting mechanism set for retarded ignition, with means for selectively connecting one of the interrupting mechanisms to the generating winding.

Another object is to provide for each position of advanced and retarded ignition, a range of adjustment-of the interrupting mechanism, to thereby further increase the total e'fiective range of timing the magneto.

' These and other objects will be apparent from the ensuing description and pointed out in the appended claims, in connection with the accompanying drawing which diagrammatically illustrates one embodiment of the invention in application, as an example, to a. magneto giving per rotation four fixed periods of flux change for ignition of a twelve cylinder four-cycle internal combustion engine.

The magneto shown has a stator core a with I poles b and c and a generating winding thereon comprising primary d and secondary e. Also it has a stationary magnet with poles g and h, and a rotor i with fiux distributing members is and m driven at three times crank shaft speed of theengine. The poles b, h, c and g are serially arranged on spacing. On the rotor shaft n isflxed a cam o with two lobes apart, and on the interrupter plate are pivoted two interrupter levers p and q carrying contacts. These levers, with the stationary contacts for them as shown, and the cam 0, form two interrupting mechanisms operative every 90, with the lever q in advance of the lever 2 in the direction of rotation indicated. The joint terminal of the primary and secondary windings is connected to the arm r of a three-point switch,

'next sparkplug at the same ignition for the engine cylinder having that ermany June 24, 1933 the other terminal of the primary winding being grounded on the core a, and the other terminal of the secondary being connected to the half-speed rotor of the distributor for the twelve sparkplugs indicated at t. The halfspeed of- 5 the distributor rotor is with reference to the crankshaft speed of the engine. The arm r selectively connects the interrupter mechanisms to the generating winding as shown through the advance and retard terminals of the switch, as 10 shown. The interrupter plate has a manual timing lever u for conjoint angular adjustment of the interrupting levers p and q and their fixed contacts, with respect to the cam o.

In the position shown on the drawing, the i6 trailing tips k and m of the flux distributors are starting to leave the trailing tips of the poles b and 0 respectively, and the cam o is starting to separate the contact of lever q from its stationary contact. Starting substantially 20 at this moment, there is reduction of the magnetic flux in the core 0, followed by a building up of the flux in the reverse direction therein. Simultaneously, the circuit of the primary winding d which is closed through arm 1', interrupter 25 lever q and the ground, isinterrupted by q to further increase the time rate change of magnetic flux in the core a. with the well known results. The resulting ignition voltage generated in the generating winding d, e, and the occur- 3 rence of a spark at the proper one of the sparkplugs t,'occurs at the instant of advanced ignition for the engine cylinder having that sparkplug. At 180 rotation of shaft n from the position shown, another spark will occur at the 5 instant of advanced sparkplug. At the two intermediate 90 positions, there will be a reversal of the flux from the magnet poles h and g through the core a, 40 and an opening of the interrupter lever p by a lobe of the cam 0, but there will beno spark at a sparkplug since the primary winding d remains closed through interrupter lever q and switch arm 1'. Thus, with this position of switch 45 arm r, there will be two ignition voltages generated per rotation of rotor z, occurring 180 apart and both at the instant of advanced ignition for the respective cylinders.

.Whenever it is desired, as in starting, to 59 change the instant of ignition in each of the engine cylinders to retard the ignition, the switch arm 1' is closed on the upper terminal so that the interrupter lever p is connected tothe generating winding and the lever 11 disconnected 515i therefrom. The circuit of the primary winding d will then be opened at the two intermediate points 90 and 270 from the position of the rotor i shown on the drawing, at which points the trailing tips k and 111. will start to leave the trailing tips of the magnet poles h and 0, instead of the stator core poles b and c as previously desc'. ibed for advanced ignition. Starting substantially at each of these intermediate points, there is a reduction of the magnetic flux in the core a iollowed by a building up of the flux in the reverse direction, and the circuit of the primary winding d is opened at the contacts oi interrupter p, thereby producing a spark at each of the same sparkplugs as before but at the instant of retarded ignition for the respective engine cylinders. Obviously no ignition current is now produced in the generating winding at the positions corresponding to advanced ignition. Thus, with this position 0! switch arm. 1-, there will be two ignition sparks per rotation oi rotor i, occurring 180 apart and both at the instant of retarded ignition for the respective cylinders, but their angular positions are midway between the two positions for advanced ignition.

As will now be understood, diiierent periods 01 flux change are utilized for advanced andretarded ignition, to thereby produce equally eii'ective ignition currents at both advanced and retarded ignition in all cylinders of the engine and also to obtain such currents at widely separated positions mounting in this case to 30 between advanced and retarded positions. For engines having twelve or more cylinders, this method of ignition is particularly eflfective in comparison with prior magnetos utilizing all sparking positions for both advanced and retarded ignition, because of the greater angular movement of the rotor i between sparks obtained in accordance with this invention. For tour cycle engines having more than four cylinders, this magneto, which is of the type delivering two ignition sparks per rotation, would be driven at greater than crank shaft speed. A twelve cylinder engine would require a magneto rotation of three times crank shaft speed. The angle between advance and retard as. measured on the crank shait'is thus reduced to 30. Similarly, asixteen cylinder engine requires a magneto rotation of four times crank shaft speed, and the above angle becomes 22.5". It will also be apparent that alternative magnetos may be used which deliver a diflerent number of ignition sparks per rotation than the type above described. In such cases the magneto rotor speed of each type would diner, but the angle between advance and retard, as measured on the crank shait, would in each case be the same as for the type above described.

Obviously, this invention may be utilized with a magneto in which the magnetic flux is not reversed in the generating winding, but is reduced to zero or substantially so and thereafter built up in the same direction. In the appended claims, flux change is intended to cover the reduction to substantially zero as well as a reversal oi the iiux at the instant oi ignition, but

. is not intended to include such change as occurs when the flux is altered comparatively slightly during a period to provide advanced or retarded ignition during the one period.

It desired, the periods of ignition, whether ad- I vanced or retarded, may be varied manually by the lever u. This further enlargesthe angular separation of the instant of advanced and retarded ignition and/or fills in, partially at least, the angular position between the advanced and retarded positions described. Oi course, the efiectiveness of the spark produced in these angular positions is altered in the same way as that occurring in prior magnetos having adjustment oi the interrupting mechanism. Obviously, a governor may be substituted for the lever u or may be applied to the cam o.

What is claimed is:

1. The method of obtaining advanced and retarded ignition from a magneto having at least two periods of flux change per rotation, which consists in providing twice as many possible periods of ignition as are required, and selecting alternate ones of said periods for advanced ignition and the intermediate alternate ones of said periods for retarded ignition.

2. The method of obtaining advanced and retarded ignition from a magneto which has at least two periods of flux change per rotation and which has one interrupting mechanism set for operation at certain of said periods and anset for operation at the intermediate alternate ones of said periods, which consists in selecting one of the interrupting mechanisms for inter-' rupting the circuit of the generating winding of the magneto for advanced ignition and in selecting the other mechanism for interrupting said circuit for retarded ignition. 4. The method of obtaining advanced and retarded ignition from a magneto which has at least two periods of flux change per rotation and which has one interrupting mechanism set ior operation at certain of said periods and another interrupting mechanism set for operation at other of said periods, which consists in selecting one of the interrupting mechanisms for interrupting the circuit 0! the generating winding of the magneto tor advanced ignition and in selecting the other mechanism for interrupting said circuit for retarded ignition and conjointly adjusting both interrupting mechanisms with respect to all said periods.

5. In combination with a magneto having a generating winding and at least two periods of flux change per rotation, interrupting mechanism i'or interrupting the circuit or said winding at certain of said periods, and another inter,-

rupting mechanism for interrupting said circuit at certain other of said periods, of selector means for selecting one of said mechanisms for advanced ignition and the other of said mechanisms ior retarded ignition.

6. In combination with a magneto having a ranged to interrupt said circuit at the intermediate alternate ones of said periods, or selector means for selecting one of said mechanisms for advanced ignition and the other of said mechanisms for retarded ignition.

7. In combination with a magneto having a generating winding andaneven number 01 periods o1 flux change per rotation, interrupting mechanism arranged to interrupt the primary 10 circuit of said winding at alternate ones of said periods, and another interrupting mechanism arranged to interrupt said circuit at the intermediate alternate ones of said periods, of selector means for selecting one of said mechanisms for advanced ignition and the other of said mechanisms for retarded ignition, and means for conjointiy adjusting the instant of operation of the interrupting mechanisms.

ERICH KLAIBERQ