US3720195A

US3720195A - Ignition system for multi-cylinder internal combustion engines

Info

Publication number: US3720195A
Application number: US00122982A
Authority: US
Inventors: H Fujii
Original assignee: NipponDenso Co Ltd
Current assignee: Denso Corp
Priority date: 1970-03-25
Filing date: 1971-03-10
Publication date: 1973-03-13
Anticipated expiration: 1990-03-13
Also published as: CA936214A

Abstract

An ignition system for multi-cylinder internal combustion engines is disclosed, which comprises a plurality of electrically independent, ignition power generating coils wound on respective main cores arranged side by side along a line at right angles to the rotor shaft of a magnet generator, said main cores being magnetically coupled with a pair of auxiliary cores arranged such that the magnet flux from the magnet pole pieces of said magnet generator pass by these auxiliary cores. The ignition power generating coils are each connected in parallel to an ignition coil and with an interrupter switch.

Description

United States Patent 091 Fu'ii 1 1March 13, 1973 I 1 IGNITION SYSTEM FOR MULTI- 1,620,060 3/1927 Billon et al. ..123 149 1) CYLINDER INTERNAL COMBUSTION s t k aa ENGINES 2,990,112 6/1961 Levy et al. [75] Inventor: Hideo Fujii, Kariya, Japan 3,566,851 3/1971 Pfrommer 3,495,579 2/1970 Davalillo ..123/l49 R [73] Assrgnee: Nlppondenso Co., Ltd., Kariya-shi,

Alchl'ken' Japan Primary Examiner-Laurence M. Goodridge 22 il Mal-ch 10 1971 Assistant ExaminerCort Flint Attorney-Cushman, Darby & Cushman [21] App]. No.: 122,982

[57] ABSTRACT Foreign Application Priority Data An ignition system for multi-cylinder internal com- March 13,1970 Japan ..45 24s14 busticl elgines is dimmed which Comprises a P rality of electrically independent, ignition power 52 us. (:1. .123/149 0, 310/153 generating mils Wmmd respective was 51 Im. c1 ..F02p 1/02 ranged side by Side a angles [58] Field of Search .....123/148 E,' 148 DC, 148 AC, rolfor Shaft f a magnet generator, sa d main (.;(')res 123/149 K149 13,149 A, 148,149; being magnetically coupled with a pair of aux1l1ary 310/156 154 153 67 cores arranged such that the magnet flux from the 1 magnet pole pieces of said magnet generator pass by [56] References Cited these auxiliary cores. The ignition power generating v coils are each connected in parallel to an ignition coil UNITED STATES PATENTS and with an interrupter switch.

1,022,832 4/1912 Durbin ..123/149 D 3 Claims, 9 Drawing Figures 'llllll 1m it "lIllIlllll mm. 3191s SHEET 2 OF 2 1N VENTOR ATTORNEYS IGNITION SYSTEM FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINES This invention relates to a magnet-type ignition systems for multi-cylinder internal combustion engines.

In the magnet-type ignition system without an ignition distributor for multi-cylinder internal combustion engines, a plurality of ignition power generating coils should be provided in the magnet generator in order to ensure the ignition of air-fuel mixture in the respective cylinders. Particularly, where the magnet generator also includes power generating coils for lighting and charging purposes, and where a plurality of ignition coils are used for individual cylinders, as, for instance, in two-cycle multi-cylinder engines, a plurality of electrically independent, ignition power generating coils should be provided in such a manner that each N-S pole pair of the rotor of the magnet generator has substantially a uniform influence on all these coils.

A typical example of the well-known ignition system of the kind, to which the invention pertains, will now be described in detail with reference to the accompanying drawing, in which:

FIG. 1 is a fragmentary sectional view showing a magnet generator in the conventional magnet-type ignition system;

FIG. 2 is an enlarged perspective view ofa main part of the magnet generator shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing an example of the state of the conventional magnet generator mounted on an actual engine;

FIG. 4 is an end view, partly in section, showing a magnet generator used in the ignition system according to the invention;

FIG. 5 is a sectional view taken along line V V in FIG. 4;

FIGS. 6, 7 and 8 are partial perspective views showing examples of the ignition power generating coil to be mounted in the magnet generator of the ignition system according to the invention; and

FIG. 9 is a circuit diagram showing the circuit connection of the ignition system according to the invention.

Referring now to FIGS. 1 and 2, there is shown a conventional magnet generator construction, in which electrically independent, ignition power generating coils 7 and 7' are provided. The coils 7 and 7 are respectively wound on separate cores l5 and These coil units are arranged side by side along rotor shaft 16 with spacer l4 interposed between them. They are secured to support base 13 by means of bolts 9.

The magnet generator of the construction described above, however, presents various problems. With this construction, if it is intended to disassemble or replace one ignition power generating coil unit, for instance coil 7, the other ignition power generating coil unit should also be disassembled. Also, since the coil units are first stacked together, then secured to the support base 13 by bolts 9 and thereafter machine finished so as to provide a predetermined gap between the cores I5 and 15' on one hand and the pole pieces 3 of the rotor on the other hand, it is extremely difficult to successfully reassemble the disassembled coil unit.

Further, from the aspect of cost, the cores 15 and 15' are usually made of a lamination of expensive silicon steel plates because of high frequency transient phenomena involved in the operation of the generator. Because the cores l5 and 15' have a narrow central portion wrapped with the coil and wider end portions, a great deal of extra or waste material is required, thus resulting in increased material cost.

Furthermore, since the cores 15 and 15' of the core units are spaced apart by the spacer 14, the pole pieces 3 of the rotor should have an increased area to cover the corresponding face of the coil units. If the ignition power generating oils 7 and 7' are obliged to be arranged such that they axially deviate from the pole pieces 3 of the rotor due to, for instance, an obstacle 17 on the engine side as shown in FIG. 3, extreme unbalance between the outputs of the coils 7 and 7' is likely to result, which is a fatal disadvantage from the aspect of ignition performance. Also, where three or more ignition power generating coils are employed, the axial dimension of the rotor and hence the rotor shaft 16 should be increased, which is very disadvantageous from the aspects of engine design and engine appearance.

An object of the invention, accordingly, is to provide an ignition system which can overcomeall the above drawbacks and ensures reliable ignition performance.

More particularly, it is an object of the invention to provide an ignition system for multi-cylinder internal combustion engines comprising a plurality of electrically independent ignition power generating coils wound on respective main cores arranged side by side along a line at right angles to the rotor shaft of a magnet generator, said main cores being magnetically coupled with a pair of auxiliary cores arranged such that the pole pieces of the rotor of said magnet generator to pass a magnet flux to these auxiliary cores, said ignition power generating coils each being connected in parallel with an associated ignition coil and with an associated interrupter switch.

According to the invention, it is featured that the disassemblage or replacement of the ignition power generating coils may be made very simply, the waste material can be reduced to reduce the material cost of the cores, reliable ignition performance free from unbalanced outputs of the ignition power generating coils can be ensured, and it is possible to stack three or more ignition power generating coils together. Thus, the invention provides outstanding benefits in respect of design, performance, cost and assemblage of magnettype ignition systems and multi-cylinder internal combustion engines using them. i

The invention will now be described in conjunction with a preferred embodiment thereof with reference to FIGS. 4 and 5. Referring to the Figures, a magnet generator is shown having a rotor including a cup shaped magnetic member 1 provided with circumferentially spaced, radially polarized magnets 2 each integral with a pole piece 3. The magnetic member I is secured to a hub member4 secured to a rotorshaft 16, which may be connected to the engine crankshaft. The stator part of the magnet generator includes ignition power generating coils 7 and 7' wound on respective main cores 8 and 8' magnetically coupled with a pair of auxiliary cores 5 and 6 arranged to be passed by a magnet flux from the pole pieces 3 of the rotor. The cores 8 and 8' are arranged side by side along a line at right angles to the rotor shaft 116. Each of the cores 8 and 8' has its opposite ends snugly received in corresponding grooves formed in the auxiliary cores 5 and 6 and extending in the direction of the axis ofthe rotor shaft 16, as shown in FIG. 4. The auxiliary cores 5 and 6 are secured by bolts 9 to a support base 13. Interrupters l0 and 10' are attached to the support base 10 substantially symmetrically with respect to a cam 4a of the hub member 4. The support base 10 also carries capacitors 11 and 11. Numeral 12 designates a lighting or charging power generating coil disposed on the side of the rotor shaft 16 opposite the ignition power generating coils 7 and 7.

FIG. 9 shows the circuit connection of various parts of the ignition system including the magnet generator described above. The ignition power generating coil 7 is connected in parallel with interrupter contacts 10, capacitor 11, and the primary winding 18 of an ignition coil 21, whose secondary winding 19 is connected to a spark plug electrode 20. The other ignition power generating coil 7 is connected in parallel with interrupter contacts 10', capacitor 11 and primary winding 18' of another ignition coil 21', whose secondary winding 19 is connected to a spark plug electrode for another cylinder.

Wlth the construction described above according to the invention, in which the

cores

8 and 8 for the ignition power generating coils 7 and 7 are so arranged such that their opposite ends can snugly fit in the corresponding grooves in the auxiliary cores 5 and 6, the

cores

8 and 8 and the auxiliary cores 5 and 6 are coupled not only magnetically but also mechanically. Thus, the

cores

8 and 8 and auxiliary cores 5 and 6, though they are separate component parts, may be assembled into an integral unit, which may then be secured to the support base 13 by bolts 9 with extreme ease. Also, it is possible to previously secure the auxiliary cores5 and 6 to the support base 13 and thereafter fit the

cores

8 and 8" in them. This means that the present invention system unlikes the conventional coil arrangement, in order to disassemble or replace one ignition power generating coil there is no need of removing both the ignition power generating coilunits, nor'removing the auxiliary cores 5 and 6. In other words, it is possible to carry out the disassemblage or replacement of the ignition power generating coil simply, securely and speedily without causing any possible resultant change of the gap between the pole pieces of the rotor and the auxiliary cores 5 and 6.

' To this end, the ends of the

cores

8 and 8 may be of a flared profile as indicated at 8a, 8'a in FIG. 6 and at 8b, 87b in FIG. 7, or they be of a rectangular profile as indicated at 8c, 8c in FIG. 8.

The lamination in the cores 8 and 8' may be widthwise as shown in FIG. 6 or thickness-wise as shown in FIG. 7. In either case, the same effects may be obtained.

As an alternative construction, one of the cores, for instance core 8 may be made integral with the auxiliary cores 5 and 6 so that the other core 8 may be subsequently fitted.

Since the core 8 or 8' shown in FIG. 6 to 8 has a substantially uniform width or thickness over its length, less material is wasted compared to the conventional cores 15 and 15' shown in FIGS. 1 and 2, greatly contributing to the reduction of the core material cost.

In the performance aspect, unlike the conventional arrangement of cores 15 and 15' axially arranged side by side and spaced apart by spacer 14 as shown in FIGS. 1 and 2, the auxiliary cores 5 and 6 according to the invention may provide a sufficient area to face the pole pieces 3 of the rotor, and the magnetic flux may be uniformly distributed to the

cores

8 and 8, which are securely magnetically coupled with the auxiliary cores 5 and 6. Also, the required magnetic flux may reliably pass through each of the cores 8 and 8'. Thus, even if the ignition power generating coils 7 and 7' are obliged to be arranged such that they slightly axially deviate from the pole pieces 3 of the rotor, outputs of the same magnitude may be obtained from the ignition power generating coils 7 and 7 so that reliable performance of the ignition system may be ensured.

Further, three or more ignition power generating coils may be readily provided without altering the axial dimension of the rotor.

Furthermore, although the preceding embodiment is concerned with an outside rotor type magnet generator, the core construction and arrangement according to the invention may of course be applied to inside rotor type magnet generators.

What is claimed is:

1. In an ignition system for multi-cylinder internal combustion engines having ignition coils, interrupters, and a magnet generator with at least two ignition power generating coils independent with each other, said magnet generator comprising:

a rotor including a rotor shaft and a plurality of magnetic pole pieces, said pole pieces being disposed on said rotor with predetermined separations;

a stator arranged with a coaxial relationship with said rotor;

a pair of auxiliary cores disposed on said stator so as to be capable of facing towards said pole pieces of said rotor;

at least two main cores, connected to said pair of auxiliary cores therebetween in parallel relation with each other, for magnetically coupling said respective auxiliary cores so as'to pass a magnetic flux from said pole pieces therethrough, said main cores being arranged side by side on the same side of said rotor shaft and on a plane perpendicular to the axial direction of said rotor shaft;

said ignition power generating coils being wound on said respective two main cores, whereby electromotive forces are generated in said respective ignition power generating coils independently and simultaneously as said rotor rotates.

2. An ignition system according to claim 1, wherein the ends of said main cores are a flared profile.

3. An ignition system according to claim 1, wherein the ends of said main cores are a rectangular profile.

Claims

1. In an ignition system for multi-cylinder internal combustion engines having ignition coils, interrupters, and a magnet generator with at least two ignition power generating coils independent with each other, said magnet generator comprising: a rotor including a rotor shaft and a plurality of magnetic pole pieces, said pole pieces being disposed on said rotor with predetermined separations; a stator arranged with a coaxial relationship with said rotor; a pair of auxiliary cores disposed on said stator so as to be capable of facing towards said pole pieces of said rotor; at least two main cores, connected to said pair of auxiliary cores therebetween in parallel relation with each other, for magnetically coupling said respective auxiliary cores so as to pass a magnetic flux from said pole pieces therethrough, said main cores being arranged side by side on the same side of said rotor shaft and on a plane perpendicular to the axial direction of said rotor shaft; said ignition power generating coils being wound on said respective two main cores, whereby electromotive forces are generated in said respective ignition power generating coils independently and simultaneously as said rotor rotates.