GB1575636A

GB1575636A - Ignition control units

Info

Publication number: GB1575636A
Application number: GB38050/77A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1976-09-14
Filing date: 1977-09-13
Publication date: 1980-09-24
Also published as: DE2641239A1; JPS5335973A; SE7710247L; FR2364341A1

Description

(54) IMPROVEMENTS RELATING TO;IGNITION CONTROL UNITS (71) We, ROBERT BOSCH GmbH, a German Company, of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to an ignition control unit for controlling the ignition operation in internal combustion engines.

German Offenlegungsschrift 1,539,173 has already described an electrical ignition system which is based on the interruption or reflection of a beam of light, the light being guided in light guides. The described invention has the disadvantage that two conductors have to be guided to, and secured to, the moved component reflecting or interrupting the beam of light, and that the two light guides have to be accurately adjusted. This requires small manufacturing tolerances and expensive adjustment in the case of mass production.

According to the present invention there is provided an ignition control unit for controlling the ignition operation of an internal combustion engine, said control unit comprising a light guide having at least two light conducting channels, a light source being arranged adjacent to one end of one light conducting channel of the light guide, the other end of said one light conducting channel being located adjacent a component which is arranged to be driven by the engine, another light conducting channel being arranged to collect reflected radiation from said component and conduct said reflected radiation to a light-sensitive electrical switching member arranged to trigger ignition signals in dependence upon the reflected radiation received, the cross-sectional configuration of the end of at least said another light conducting channel, adjacent to said component, being in the form of a flat strap extending transversely of the direction of movement of said component.

An arrangement in accordance with the present invention, has the advantage that only one light guide having at least two channels is used. This arrangement enables assembly to be effected with large tolerances; subsequent adjustment is no longer required.

It is particularly advantageous that the cross-sectional configuration of the lightreturning portion of the light guide is in the form of a flat strip arranged transversely of the direction of movement of the component, particularly at its end facing the movable component. Thus, steep switching pulses having accurately fixed triggering points can be obtained in dependence upon the reflection and can be further processed in a simple manner. A further advantage of the invention is that a coding can be provided on the movable component which is preferably in the form of a rotating disc. The coding may vary the intensity or colour of the light conducted to the photo-sensitive electrical switching member.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates a preferred embodiment of a control unit according to the present invention; and Fig. 2 is a section, drawn to an enlarged scale, through a preferred embodiment of the end of the light guide facing the movable component.

A rotating disc 10 is illustrated in Fig. 1 and is driven by means of an engine (not illustrated). In the simplest case, the disc can be mounted directly on the crankshaft.

Recesses 11 are formed in the periphery of the disc. A light guide 12 is arranged close to the disc and, in the present case, its end facing the disc is in the form of a flat strip. The end of the light guide remote from the disc is split up into two channels. One channel is fed by means of a light source 13. By way of example, lamps can be used as the light source, although it is particularly advantageous to use light-emitting semiconductor components. The other channel terminates in a light-sensitive component 14. By way of example, light-sensitive semiconductor components may be used as the light-sensitive component. The light-sensitive component 14 is connected to a pulse shaper 15 from the output 16 of which may be tapped a signal.

The light transmitted by the light source 13 is transmitted to the rotating disc means of one of the channels of the light guide. When a projection is located opposite to the light guide, substantially the entire quantity of light emitted is reflected and is transmitted to the light-sensitive electrical component 14 by way of the second channel of the light guide. A signal is formed therefrom by means of the pulse shaper and is present at, for example, the output 16 at the level of the operating voltage. When a depression 11 is located opposite to the light guide, the quantity of the reflected light is reduced. By way of example, a voltage is then present at the output 16 which differs only slightly from zero potential.

The pulses at the output 16 control the ignition system of an internal combustion engine. The number of recesses in the rotating disc is then equal to the number of the cylinders of the internal combustion engine, so that the corresponding number of pulses is produced.

The cross-sectional configuration of the end of the light guide facing the moved component is in the form of a flat strip arranged transversely of the direction of movement of the component, as is shown in Fig. 2. Fig. 2 shows an enlarged section through the light guide in the vicinity of the disc. A channel 20 is used as a light-conducting channel, and a further channel 21 is used as a light-returning channel. Alternatively, as is shown in Fig. 2, the light-returning channel 21 may be of multi-channel construction.By constructing the light guide in the form of a flat strip, the alternately reflective and less reflective surfaces of the rotating disc produce a very accurate signal for further processing, the signal having very steep edges and being virtually independent of the rotational speed and the intensity of the light source or the distance between the light guide and the rotating component.

A further development of the present invention resides in providing the periphery of the disc with reflective and non-reflective portions instead of recesses. By way of example, this can be effected by alternate black and white coloured marks or by a reflecting surface and a non-reflecting surface.

A further possibility of coding the disc is that of providing the disc with projections of differing height. The luminous intensity then received by the light-sensitive component 14 is then dependent upon the height of the projection on the disc. When the pulse shaper 15 is constructed with a plurality of outputs and each of these outputs opens in dependence upon a fixed luminous intensity, the system can, for example, be used for the direct control of the individual spark plugs. A further possibility of application is to code the disc with various colours. When a plurality of light-sensitive components 14, each responsive only to a respective colour, are provided instead of one light-sensitive component, and pulse shapers are connected to the outputs thereof, the individual spark plugs are also directly controllable in the case of an ignition system.When the light guide is of multi-channel construction, it is possible to cover an optional number of functions of interest in the case of an engine. In addition to the instant of ignition, the rotational speed, the top dead centre of a cylinder or other quantities of interest in an engine may be picked up. Coding can then be effected either channel-wise or by means of known codes such as, for example, the Gray code, BCD code. A number of light-sensitive components equal to the number of channels then have to be provided at the end of the light guide in addition to the light source and are then connected to a code converter circuit. The code also has to be provided on the surface of the disc in addition to the periphery of the disc.

It is particularly advantageous when the rotating disc 10 and the end of the light guide 12 facing the disc are accommodated in a housing closed on all sides. This avoids soiling of the light guide, which might lead to faulty pulses.

WHAT WE CLAIM IS: 1. An ignition control unit for controlling the ignition operation of an internal combustion engine, said control unit comprising a light guide having at least two light conducting channels, a light source being arranged adjacent to one end of one light conducting channel of the light guide, the other end of said one light conducting channel being located adjacent a component which is arranged to be driven by the engine, another light conducting channel being arranged to collect reflected radiation from said component and conduct said reflected radiation to a light-sensitive electrical switching member arranged to trigger ignition signals in dependence upon the reflected radiation received, the cross-sectional configuration of the end of at least said another light conducting channel, adjacent to said component, being in the form of a flat strap extending transversely of the direction of movement of said component.

2. A control unit as claimed in claim 1, in which a rotating disc is used as the movable component and its periphery has recesses or projections for producing a coded light signal, and devices for decoding this signal are provided.

3. A control unit as claimed in claim 1 or 2, in which regions of differing reflective power

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. component. The light-sensitive component 14 is connected to a pulse shaper 15 from the output 16 of which may be tapped a signal. The light transmitted by the light source 13 is transmitted to the rotating disc means of one of the channels of the light guide. When a projection is located opposite to the light guide, substantially the entire quantity of light emitted is reflected and is transmitted to the light-sensitive electrical component 14 by way of the second channel of the light guide. A signal is formed therefrom by means of the pulse shaper and is present at, for example, the output 16 at the level of the operating voltage. When a depression 11 is located opposite to the light guide, the quantity of the reflected light is reduced. By way of example, a voltage is then present at the output 16 which differs only slightly from zero potential. The pulses at the output 16 control the ignition system of an internal combustion engine. The number of recesses in the rotating disc is then equal to the number of the cylinders of the internal combustion engine, so that the corresponding number of pulses is produced. The cross-sectional configuration of the end of the light guide facing the moved component is in the form of a flat strip arranged transversely of the direction of movement of the component, as is shown in Fig. 2. Fig. 2 shows an enlarged section through the light guide in the vicinity of the disc. A channel 20 is used as a light-conducting channel, and a further channel 21 is used as a light-returning channel. Alternatively, as is shown in Fig. 2, the light-returning channel 21 may be of multi-channel construction.By constructing the light guide in the form of a flat strip, the alternately reflective and less reflective surfaces of the rotating disc produce a very accurate signal for further processing, the signal having very steep edges and being virtually independent of the rotational speed and the intensity of the light source or the distance between the light guide and the rotating component. A further development of the present invention resides in providing the periphery of the disc with reflective and non-reflective portions instead of recesses. By way of example, this can be effected by alternate black and white coloured marks or by a reflecting surface and a non-reflecting surface. A further possibility of coding the disc is that of providing the disc with projections of differing height. The luminous intensity then received by the light-sensitive component 14 is then dependent upon the height of the projection on the disc. When the pulse shaper 15 is constructed with a plurality of outputs and each of these outputs opens in dependence upon a fixed luminous intensity, the system can, for example, be used for the direct control of the individual spark plugs. A further possibility of application is to code the disc with various colours. When a plurality of light-sensitive components 14, each responsive only to a respective colour, are provided instead of one light-sensitive component, and pulse shapers are connected to the outputs thereof, the individual spark plugs are also directly controllable in the case of an ignition system.When the light guide is of multi-channel construction, it is possible to cover an optional number of functions of interest in the case of an engine. In addition to the instant of ignition, the rotational speed, the top dead centre of a cylinder or other quantities of interest in an engine may be picked up. Coding can then be effected either channel-wise or by means of known codes such as, for example, the Gray code, BCD code. A number of light-sensitive components equal to the number of channels then have to be provided at the end of the light guide in addition to the light source and are then connected to a code converter circuit. The code also has to be provided on the surface of the disc in addition to the periphery of the disc. It is particularly advantageous when the rotating disc 10 and the end of the light guide 12 facing the disc are accommodated in a housing closed on all sides. This avoids soiling of the light guide, which might lead to faulty pulses. WHAT WE CLAIM IS:

1. An ignition control unit for controlling the ignition operation of an internal combustion engine, said control unit comprising a light guide having at least two light conducting channels, a light source being arranged adjacent to one end of one light conducting channel of the light guide, the other end of said one light conducting channel being located adjacent a component which is arranged to be driven by the engine, another light conducting channel being arranged to collect reflected radiation from said component and conduct said reflected radiation to a light-sensitive electrical switching member arranged to trigger ignition signals in dependence upon the reflected radiation received, the cross-sectional configuration of the end of at least said another light conducting channel, adjacent to said component, being in the form of a flat strap extending transversely of the direction of movement of said component.

are provided on the rotating disc for the purpose of producing a coded light signal, and devices for decoding this signal are provided.

4. A control unit as claimed in claim 1 or 2, in which coloured marks are provided on the rotating disc for the purpose of producing a coded light signal, and devices for decoding this signal are provided.

5. An ignition control unit for controlling the ignition operation of an internal combustion engine, said control unit being constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.