GB2077850A

GB2077850A - An Ignition Device for an Internal Combustion Engine

Info

Publication number: GB2077850A
Application number: GB8018776A
Authority: GB
Original assignee: Atlas Aluminium Fahrzeugtechnik GmbH
Current assignee: Atlas Aluminium Fahrzeugtechnik GmbH
Priority date: 1980-06-09
Filing date: 1980-06-09
Publication date: 1981-12-23
Also published as: EP0041666A1; ES267294Y; ES267294U; SU973036A3

Description

SPECIFICATION An Ignition Device for an Internal-Combustion Engine The invention relates to an ignition device for internal-combustion engines and more particularly concerns such a device of the type that comprises a toothed wheel which in use is synchronously coupled with the crankshaft of the engine, a signal head associated with the toothed wheel and provided with a pot magnet, and a succeeding pulse generator. An ignition device of the above kind is described in the German 'Auslegeschrift' 25 32 226. In this known device the toothed wheel is directly connected to the crankshaft and is provided with approximately 100 teeth, preferably 96 teeth. As is generally known, during a complete working cycle of a four-stroke engine, a crankshaft completes two revolutions so that 192 pulses are produced over a complete working cycle. In practice, it has been found that this number of pulses is expedient for accurate control of ignition pulses. When assembling a new engine and providing it with an electronic ignition device, the toothed wheel may be mounted easily on the axle of the crankshaft. Particularly in connection with the flywheel, or the like, it is possible to provide such a toothed wheel. It is also possible to use the toothed wheel rim, engaged by the starter, for this. However, when converting an existing internal-combustion engine to electronic ignition, difficulties arise due to the fact that arrangement of the toothed wheel on the axle of the crankshaft is only possible with considerable expenditure. It is the object of the invention to provide an ignition device which is suitable for fitting to existing internal-combustion engines. According to the invention, there is provided an ignition device for an internal-combustion engine, comprising a toothed wheel mountable on the ignition distributor shaft and having between 40 and 60 teeth, a signal head associated with the toothed wheel and provided with a pot magnet, the inner core of which has a diameter of less than 2.0 mm, a pulse generator connected to the output of the signal head, and a pulse quadrupler connected to the output of pulse generator for multiplying the number of pulses produced by the pulse generator by a factor of 4. Thus, the invention utilizes the existing ignition distributor. The toothed wheel is mounted on the ignition distributor shaft. As is generally known, the speed of rotation of the ignition distributor shaft is less than that of the engine crankshaft in a ratio of 2:1. On the basis of the usual dimensions of the ignition distributor it is possible to provide 48 teeth on the toothed wheel without difficulty. The pot magnet can then be dimensioned accordingly. The pulses of the pulse generator are then multiplied by a factor 4 in order to obtain the number of pulses required for accurate control of the ignition pulses. Such an ignition device can easily be fitted to an existing internal-combustion engine at any time so that the advantages of electronic ignition can also be utilized. The invention will now be more particularly described, by way of example, with reference to the accompanying drawing, wherein:- Figure 1 is a schematic view of an internal combustion engine provided with one embodiment of an ignition device according to the invention; Figure 2 is a part sectional view of the ignition device, and Figure 3 is a plan view, partly sectioned of the device shown in Figure 2. Referring to Figure 1 there is shown therein an internal-combustion engine 1 having a cylinder block 2 within which is indicated an axis 3 of a crankshaft. An ignition distributor shaft 4 which extends into an ignition distributor housing 5 is driven by the crankshaft, sometimes via one or more intermediate gears. The speed of rotation of the ignition distributor shaft 4 is reduced in the ratio 2:1 relative to the speed of the crankshaft so that the ignition distributor shaft 4 does one revolution during one complete working cycle of a four-stroke engine. Referring to Figure 2, a toothed wheel 6 is keyed on the ignition distributor shaft 4 within the ignition distributor housing 5. A signal hej 7 is disposed radially outwards of the toothed wheel 6. The signal head 7 comprises a pot magnet 8 having an inner core 9 carrying signal windings such that the signal head 7 produces signals as the teeth of the toothed wheel 6 pass thereby. These signals are amplified in an amplifier 10 and actuate a pulse generator 11 which produces pulses of a desired pulse shape. The number of pulses produced by the pulse generator 11 are quadrupled in a pulse quadrupler 12. The toothed wheel 6 has, for example, 48 teeth. Consequently, the pulse quadrupler 12 produces 192 pulses for each revolution of the ignition distributor shaft 4. As stated previously, this number of pulses has proved to be expedient for accurate control of ignition pulses. The dimensions of the ignition distributor housing 5 are predetermined. If as aforesaid the toothed wheel 6 has 48 teeth, the tooth pitch will be approximately 3 mm. In order to secure a precise separation and resolution of the pulses, the inner core 9 of the pot magnet must have a diameter or less than 2 mm. The ignition device can be fitted to any existing internal-combustion engine. In this connection it is merely necessary to equip the ignition distributor shaft 4 with the toothed wheel 6 and to provide a distributor cover 13 equipped with the signal head 7. The associated electronics will comprise a pulse quadrupler 12. Thus, it is not necessary to carry out extensive alterations to the engine.

Claims

1. An ignition device for an internal combustion engine, comprising a toothed wheel mountable on the ignition distributor shaft and having between 40 and 60 teeth, a signal head associated with the toothed wheel and provided with a pot magnet, the inner core of which has a diameter of less than 2.0 mm, a pulse generator connected to the output of the signal head, and a pulse quadrupler connected to the output of pulse generator for multiplying the number of pulses produced by the pulse generator by a factor of 4.

2. An ignition device for an internal combustion engine, substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

3. An internal combustion engine having an ignition distributor and equipped with the ignition device set forth in claim 1 or claim 2, the toothed wheel being mounted on the ignition distributor shaft of the engine.