Ignition Coil-Incorporated Distributor for Internal Combustion Engines

Europaisches Patentamt European Patent Office © Publication number: 0 536 81 1 A2 Office europeen des brevets

EUROPEAN PATENT APPLICATION

@ Date of filing: 24.04.89

© Priority: 26.04.88 JP 101227/88 Hitachi-shi, Ibaraki 319-12(JP) 01.08.88 JP 190644/88 Inventor: Kobayashi, Kazutoshi 4860-6 Mutsuno, Nakane @ Date of publication of application: Katsuta-shi, Ibaraki 312(JP) 14.04.93 Bulletin 93/15 Inventor: Sugiura, Noburu 1360-27, Kasahara-cho © Publication number of the earlier application in Mito-shi, Ibaraki 310(JP) accordance with Art.76 EPC: 0 339 892 Inventor: Kawakami, Kazuhiko 1360-26 Tarasaki © Designated Contracting States: Katsuta-shi, Ibaraki 312(JP) DE FR GB Inventor: Koshida, Ryoichi 63-6 Tabiko © Applicant: HITACHI, LTD. Katsuta-shi, Ibaraki 312(JP) 6, Kanda Surugadai 4-chome Chiyoda-ku, Tokyo 101(JP) © Representative: Molyneaux, Martyn William @ Inventor: Shimada, Junichi c/o Ladas & Parry, Altheimer Eck 2 4-22, Minamikouya-cho 3-chome W-8000 Munchen 2 (DE)

© An ignition coil-incorporated distributor in which FIG. 8 an ignition coil is incorporated in a distributor housing has a core for the ignition coil located in an enclosure member (75, 76; 74) retaining the core (71). A set screw (79) fastens the enclosure member to an inner surface of the housing (2).

00 CO 00 m

Rank Xerox (UK) Business Services (3. 10/3.5x/3.0. 1) 1 EP 0 536 81 1 A2 2

Background of the Invention: wound around the cylindrical core through which a rotor shaft of the distributor passes, the ignition coil This invention relates to an ignition coil-incor- being mounted on the upper side of a bearing for porated distributor for internal combustion engines, supporting the rotor shaft. in which an ignition coil for internal combustion 5 In this distributor, the construction of the iron engines is incorporated in a distributor. core is very complicated. Further, since the ignition An example of an ignition coil-incorporated dis- coil is disposed at the upper side of the bearing for tributor for internal combustion engines is disclosed the rotor shaft, the size of the distributor increases in Japanese Patent Publication No. 60-18834/1985, in the direction of the longitudinal axis thereof by wherein the ignition coil-incorporated distributor io the height of the ignition coil. When the shaft is comprises a housing, a rotor shaft rotatably sup- connected directly to a cam shaft in an engine, the ported by the housing, a cap fitted to the housing, distance between the bearings for the shaft de- a distributor part including a rotor electrode moun- creases, so that the shaft shakes during the rotated on a rotor top end of the rotor shaft and a side tion thereof. This would cause interference of parts electrode mounted on the cap to face the rotor 75 secured to the shaft with other parts facing the electrode with a gap therebetween, an ignition coil parts and generation of an unstable output signal. secured to the housing, a signal rotor secured to When the distributor is disposed laterally in an the rotor shaft, a magnetic pickup for picking up engine, that is, the longitudinal axis of the distribu- signals and interrupting current flowing in a primary tor is disposed horizontal, the center of gravity coil of the ignition coil according to the signal to 20 thereof in the direction of the longitudinal axis cause a secondary coil of the ignition coil to induce thereof separates from the position in which the a high voltage, etc.. distributor is fixed to the engine. Therefore, the In this ignition coil-incorporated distributor, the distributor is readily vibrated, and the reliability of ignition coil is mounted on the housing at a position the strength thereof lowers. separated from the rotor shaft on one side a dis- 25 tance sufficient by means of screw passing through Summary of the Invention: a hole formed in a core of the ignition coil in a direction perpendicular to the axis of the rotor An object of the present invention is to provide shaft. an ignition coil-incorporated distributor for internal In the distributor, a portion of the distributor in 30 combustion engines, which is simple in construc- which the ignition coil is provided projects side- tion, small-sized, mechanically stable and capable ways to increase the dimensions of the distributor. of being easily assembled. Further, the weight of the ignition coil having a According to this invention there is provided an winding wound around an iron core thereof and ignition coil-incorporated distributor having a hous- provided at a side portion of the housing has a 35 ing fixed to an internal combustion engine, a shaft considerable percentage of a total weight of the inserted at its one end portion into said housing to distributor, so that the distributor becomes unstable be rotated synchronously with a crankshaft in said with respect to the longitudinal axis thereof, and internal combustion engine, a signal rotor mounted may give rise to troubles when it is mounted on a on said shaft, a rotation signal detector provided in vehicle. 40 said housing, opposed in a separated state to said Furthermore, the ignition coil is fixed by screw signal rotor, and adapted to generate a signal syn- means at right angles to the direction of the lon- chronous with the rotation of said signal rotor, and gitudinal axis of the distributor. Consequently, parts an ignition coil provided in said housing and includ- of the distributor are screwed in various directions. ing a core and primary and secondary winding This causes the distributor assembling operation to 45 around said magnetic path-forming core, charac- become complicated, and the assembling efficien- terised by an enclosure member retaining said cy to decrease. core, and a set screw fastening said enclosure Another example of the ignition coil-incorpo- member to the inner surface of said housing, rated distributor is disclosed in Japanese Patent whereby said ignition coil is fixed to the inner side Laid-Open No. 61-231708/1986, wherein an ignition 50 of said housing. coil comprises an iron core constructed of various The ignition coil is preferably incorporated into parts, that is, a cylindrical core axially elongated, a the housing by fixing the core thereof to the hous- pair of cruciform cores disposed on upper and ing by screw means in the direction in which the lower sides of the cylindrical core, respectively, rotor shaft of the distributor extends, in the same and having four (4) arm portions radially extending, 55 manner as other parts. and plate-like cores at the tips of the arm portions Therefore, by virtue of the present invention, of the cruciform cores to magnetically connect the the dimensions of the distributor as a whole de- upper and lower cruciform cores; and windings crease, and the distance between bearings for sup-

2 3 EP 0 536 81 1 A2 4

porting the shaft can be set long, whereby the rotatably supported by the housing 2, a signal rotor shaking of the shaft during the rotation thereof 3 secured to the shaft 1 and having a plurality of does not occur. The ignition coil is incorporated projections extending radially, the number of which into the housing by a sim pie assembling operation projections corresponds to the number of cylinders with the stability and strength of the distributor kept 5 of the engine (not shown), a signal pickup device 5 sufficiently high. for picking up a signal in corporation with the signal rotor 3 as a crank angle position signal which is Brief Description of the Drawings: inputted into a control unit (not shown) to generate an ignition timing signal employing the crank angle Fig. 1 is a longitudinally section view showing io position signal, etc. electric current flowing in a the construction of an embodiment of an ignition primary coil or winding of the ignition coil 7 being coil-incorporated distributor according to EP-A- interrupted according to the ignition timing signal to 0339892; induce a high voltage in a secondary coil or wind- Fig. 2 is a plan view showing the construction of ing of the ignition coil 7, that is, at an output the ignition coil-incorporated distributor of Fig. 1; is terminal of the ignition coil 7, a rotor head 4 moun- Fig. 3 is a perspective view showing the con- ted on the top of the shaft 1 , and a cap 6, fitted to struction of an iron core of an ignition coil of the the housing 2 so as to enclose the pickup device 5 ignition coil-incorporated distributor in Fig. 1; and ignition coil 7, and having a central electrode 9 Fig. 4 is a perspective view showing the con- positioned at the central portion of the rotor head 4 struction of winding in the ignition coil of the 20 and a side electrode 10 fixed thereto and posi- ignition coil-incorporated distributor in the em- tioned at one side of the rotor head 4 with a gas bodiment of Fig. 1 ; therebetween. Fig. 5 is a perspective view showing the con- The housing 2, as shown in Figs. 1 and 7, struction of the ignition coil in the embodiment includes a bottom portion 21 , a side wall portion 22 of Fig. 1; 25 upstanding from the periphery of the bottom por- Fig. 6 is a sectional view of the ignition coil tion 21, and a shaft support portion 23 projecting taken along a line VI-VI of Fig. 5; from the bottom portion 21 into the interior of the Fig. 7 is a perspective view showing the con- housing 2, whereby an annular recess 24 is defined struction of a housing of the ignition coil-incor- for accommodating the ignition coil 7. The shaft porated distributor in the embodiment of Fig. 1; 30 support portion 23 has a through hole 25 formed Fig. 8 is a longitudinally sectional view of an therein in which, as shown in Fig. 1, a ball bearing ignition coil-incorporated distributor according to 15 and a journal bearing 13 are fitted with an axial the present invention; distance therebetween. The rotor shaft 1 is rotatab- Fig. 9 is a partial horizontally sectional view of ly supported by the housing 2 through the bearings another embodiment of an ignition coil-incor- 35 15, 13. porated distributor according to the present in- The ignition coil 7, as shown in Figs. 3 to 6, vention; and comprises an iron core or core 11 made of a Fig. 10 is a longitudinally sectional view of an- plurality of core plates, and shaped annularly, a other embodiment of an ignition coil-incorpo- winding 12 including primary and secondary win- rated distributor according to the present inven- 40 dings wound around a part of the core 11, and a tion. coil electrode 8. The core 11 is inserted into the winding 12 as shown in Fig. 4 by inserting repeat- Detailed Description of the Invention: edly each several plates of the core 11 into the winding 12. An embodiment of an ignition coil-incorporated 45 The ignition coil 7 is set in the recess 24 in the distributor for internal combustion engines accord- housing 2 in a manner that the shaft support por- ing to EP - A - 0 339 892 will now be described in tion 23 is inserted in or surrounded by the annular detail with reference to Figs. 1-7. core 11 of the ignition coil 7. The ignition coil 7 has The ignition coil-incorporated distributor has fixing bores 16 formed in the iron core 11 thereof function of generating a crank angle position signal 50 so as to extend in the direction which the shaft 1 according to rotation of an internal combustion en- extends, and the iron core 11 is fixed unitarily to gine, generating a high voltage according to igni- the housing 2 by set screws 14 passing through tion timing signals generated, for example, in a the bores 16 and engaged with screw bores 26 control unit (not shown) based on the crank angle formed in the housing 2. The shaft 1 passes position signal and distributing it to an ignition plug 55 through and is surrounded by the iron core 11 of of each cylinder of the engine. The distributor, as the ignition coil 7. shown in Fig. 1, comprises a housing 2, an ignition As is shown in Fig. 1, the upper surface of the coil 7 incorporated in the housing 2, a rotor shaft 1 core 1 1 of the ignition coil 7 is in substantially the

3 5 EP 0 536 81 1 A2 6 same level of the upper end of the shaft support direction in which the shaft 1 extends, the assem- portion 23 of the housing 2, so that the axial length bling efficiency is very high, and the manufacturing of the distributor is reduced and the distance be- cost can be reduced. tween the bearings 15 and 13 can be extended. The distributor is of the type wherein the distri- The ignition coil 7 has the coil electrode 8 5 butor is directly connected to an engine cam. upstanding from the windings. The coil electrode 8 An embodiment of the ignition coil-incorporated is inserted in a hole formed in the cap 6 at one distributor according to the present invention is side, and electrically connected with an electrode described referring to Fig. 8. member 91 embedded in the housing 2 and con- In Fig. 8, a shaft 1 is inserted at its one end nected to the central electrode 9. A space 18 is io portion into a housing 2 and supported rotatably on formed between the coil electrode 8 and an inside a ball bearing 15, the shaft 1 being rotated syn- wall of the hole for accommodating the coil elec- chronously with a crankshaft (not shown) of a gaso- trode 8, and is made labyrinthic whereby the length line engine at a speed half as high as that of this of the labyrinthic space from the winding portion to crankshaft. a contact portion with the electrode member 91 is is A signal rotor 3 is secured to the shaft 1 and made long, so that atmosphere outside the distribu- has a plurality of projections radially projecting the tor is unlikely to be influenced. number of which is equal to the number of engine The operation of the embodiment of the above- cylinders. described construction will now be described. An electromagnetic pickup device 5 comprising When the shaft 1 is rotated synchronously with 20 a coil 52 and a field magnet 51 is provided in the rotation of the engine (not shown), the rotation opposition to and in a spaced state from the signal of the signal rotor 3 is detected as a crank angle rotor 3, and fixed to the housing 2. position signal of the engine, by the signal pickup A voltage induced in the electromagnetic pic- device 5 or signal detector, and this crank angle kup coil 52 in accordance with the rotation of the position signal is inputted into the control unit (not 25 signal rotor 3 is used to control the interruption of shown). This control unit outputs an ignition timing current flowing in a primary winding of the ignition signal for the engine into the distributor, and this coil 7 through an ignition amplifier 53. ignition timing signal causes a high voltage to be When the current flowing in the primary wind- induced at the output terminal of the ignition coil. ing is discontinued, a high voltage is induced in a The high voltage thus induced in the ignition 30 secondary winding of the ignition coil 7 and is coil 7 is applied from the coil electrode 8 to an distributed to ignition plugs (not shown) through an electrode 41 of the rotor head 4 through the elec- electrode 41 of a rotor head 4 and an electrode 10 trode member 91 and the central electrode 9 on provided on a cap 6. the cap 6 and discharged from the rotor head 4 to A core 71 of the ignition coil 7 is held between the side electrodes 10 on the cap 6. Owing to this 35 a pair of core holders 75, 76, which constitute an discharge, the high voltage is applied to the ignition enclosure member for the core 71 . plug in each cylinder of the engine (not shown). These two core holders 75, 76 are provided By virtue of this embodiment, the distributor as with through bores for set screws. Set screws 79 a whole can be formed to smaller dimensions or are inserted into the through bores so as to fasten compact since the shaft support portion 23 of the 40 the core holders 75, 76 to the housing 2. housing 2 is positioned on the inner side of the When a hook 77 is provided on the core holder annular iron core 11 of the ignition coil 7. The 75, the present ignition coil 7 can be hooked up center of gravity of the distributor is set in the conveniently when it is taken out. Also, when the substantially central portion of the shaft 1 in the ignition coil 7 is installed in the housing 2, it can be radial direction, and in a position in the vicinity of 45 gripped at the hook 77 and placed properly. the position in which the distributor is set in the A box type core holder (not shown) may be engine, in the direction in which the shaft 1 ex- formed in place of the core holders 75, 76 so that tends. Accordingly, the distributor can be set in the the core 71 can be inserted into and withdrawn engine stable and operated without being vibrated, from the box type core holder, with the core 71 of and the strength of the distributor is improved. 50 the ignition coil held between the core holder and Moreover, the distance between the bearings housing 2. When the core holder is formed in this 15 and 13 for the shaft 1 can be set long, and this manner, a one piece core holder can be obtained. enables the shaking of the shaft 1, rotor head 4 If set screw holes are made along a chain line and signal rotor 3 to be minimized, and stable A in the core 71, and, if the core 71 is fastened to crank angle position signal and discharge output 55 the housing 2 with set screws (not shown), a hollow signal to be supplied. is formed in the core 71 , so that the magnetic flux Since the ignition coil 7 is fixed at its iron core passage is blocked. Moreover, the efficiency of 11 to the housing by the set screws 14 in the operations for inserting and tightening set screws in

4 7 EP 0 536 81 1 A2 8 this direction becomes very low. coil (7) provided in said housing and including It is very difficult to provide screw holes, which a core (71) and primary and secondary wind- extend in the direction of the chain line A, in the ing around said magnetic path-forming core housing 2. (71), characterised by an enclosure member On the other hand, the set screws 79 in this 5 (75, 76; 74) retaining said core (71), and a set embodiment extend in parallel with the shaft 1. screw (79) fastening said enclosure member to Accordingly, the forming of screw holes and the the inner surface of said housing (2), whereby inserting and tightening of the set screws can be said ignition coil is fixed to the inner side of done easily, and this distributor is suitable to be said housing. produced automatically. The reason why the posi- 10 tions in which the set screws are arranged and the 2. An ignition coil-incorporated distributor accord- direction in which these screws are extended can ing to claim 1, wherein said enclosure member be determined favorably resides in that the core 71 (75, 76; 74) is detachably mounted on said is set via the core holder 75, 76. core, said enclosure member being fastened to Fig. 9 shows another embodiment of the is said housing so as to cause said core to be present invention, and is a partial sectional view held firmly between said housing and said taken along a plane extending at right angles to the enclosure member. shaft 1 . A core holder 78 in this embodiment is welded 3. An ignition coil-incorporated distributor accord- to a core 71 of an ignition coil 7. Even in such a 20 ing to claim 1, wherein said enclosure member structure, the same effect as in the previous em- (78) is welded to said core (71). bodiment of Fig. 8 can be obtained. Fig. 10 shows still another embodiment of the 4. An ignition coil-incorporated distributor accord- present invention. A core 7 of an ignition coil 71 ing to claim 1, wherein said enclosure member and a core holder 74 are provided with through 25 (75, 76) consists of a plurality of core holding holes at which the core 71 and core holder 74 are members, each of which is provided with a fitted loosely around a shaft 1. The through holes through bore for a screw. allow the shaft 1 to be passed therethrough. Ac- cording to this embodiment, the core 71 can be 5. An ignition coil-incorporated distributor accord- held in a miniaturized housing by effectively utiliz- 30 ing to claim 2, wherein said core (71) and said ing a space around the shaft 1 in the housing 2. enclosure member (74) are provided with The core 71 in this embodiment is fitted in a through bores at which said core and said recessed seat 27 provided in the housing 2, and it enclosure member are fitted loosely around is fixed by being pressed by the core holder 74 said shaft. consisting of a holding metal type flat plate. Ac- 35 cording to this embodiment, the core holder 74 can 6. An ignition coil-incorporated distributor accord- be formed in a simple shape, and the manufacturing to claim 1, wherein said housing (2) has a ing cost is low. recessed seat (27) in which said core (71) of According to the present invention, the distribu- said ignition coil is set. tor can be made compact and set in the engine so 40 that the distributor can be operated stably. This distributor has a high assembling efficiency, and is suitable to be produced automatically. Moreover, the construction of the constituent parts is simple. 45 Claims

1. An ignition coil-incorporated distributor having a housing (2) fixed to an internal combustion engine, a shaft (1) inserted at its one end 50 portion into said housing (2) to be rotated synchronously with a crankshaft in said internal combustion engine, a signal rotor (3) mounted on said shaft (1), a rotation signal detector (51, 52) provided in said housing, opposed in a 55 separated state to said signal rotor (3), and adapted to generate a signal synchronous with the rotation of said signal rotor, and an ignition

5 EP 0 536 81 1 A2

6 EP 0 536 81 1 A2

FIG 4

FIG. 3 EP 0 536 81 1 A2

FIG. 5

8 EP 0 536 81 1 A2

FIG. 8

9 EP 0 536 81 1 A2

FIG. 9