This invention relates to an internal combustion engine.

A standard ignition system having a high voltage distribution from a single transformer to a distributor then by way of separate high tension leads to individual spark plugs has a number of disadvantages.

One well known disadvantage is that due to the high voltages in the distributor and the long leads to the spark plugs, moisture or damage to insulation will readily affect the performance of the engine.

A further disadvantage of such systems is that arcing between the rotor arm and contacts can lead to carbonised deposits and increased resistance to both components. This can therefore decrease the effective spark at the spark plug.

Due to problems of conventional mechanical distributors, ignition systems controlled by electronic circuits including a microprocessor have been developed. One such circuit and ignition system is described in US patent

4502454. Such systems can be complex and expensive to manufacture and repair.

It is known that injection of fuel for internal combustion engines can be of advantage. However this is conventionally achieved by injecting fuel into the inlet manifold. This however creates problems especially if sensors, upon which control of the engine depends deteriorate or fail.

It is an intended object of this invention to alleviate one or more of the above problems or at least provide the public with a useful alternative.

Accordingly there is proposed a multi-cylinder internal combustion spark ignition engine including a low voltage electrical supply, a distribution means synchronously coupled to the engine drive means and adapted to direct synchronously with the drive of the motor current at the low voltage to each of a plurality of ignition coils in turn coupled through a high voltage side of the respective coil to a respective spark plug for a respective cylinder for effecting

a spark within the spark plug.

Alternatively there is proposed a multi-cylinder internal combustion spark ignition engine including a low voltage electrical supply, a distribution means synchronously coupled to the engine drive means and adapted to direct synchronously with the drive of the motor current at the low voltage to each of a plurality of ignition coils in turn coupled through a high voltage side of the respective coil to a respective spark plug for a respective cylinder for effecting a spark within the spark plug, fuel injection means associated with each cylinder and the distribution means being further adapted to, synchronously with the drive means of the engine, inject fuel into each of the cylinders.

Preferably there is proposed a multi-cylinder internal combustion spark ignition engine as in either one of the last preceding claims further characterised in that the distributor means is adapted to provide distribution by rotation of a first rotor arm connected to a drive shaft coupled through a mechanical drive connection to the drive means of the engine .

In preference, the insulation section is of a dimension relative to the conductive means such that the conductive means will not bridge across two adjacent commutator segments.

In an alternative preferred form there are two sets of breaker points adapted to open and at different times, the breaker points both being adapted to close and then open during the conductive means being in mechanical contact with a commutator segment.

In preference, the one of the first set of breaker points are attached to the advance and retard plate to provide a spark for a varying first firing angle, and the second set of breaker points provides a spark for a substantially constant second firing angle.

In preference, the first set of breaker points is adapted to provide a spark between 20 to 6 degrees top dead centre and the second set of breaker points is adapted to provide a spark at substantially top dead centre.

Alternatively there is proposed a method of distribution for an ignition system of multi-cylinder internal combustion engine selectively restricting or ceasing

current flowing to one of a plurality of ignition coils by a mechanical switching means, each of the ignition coils having a high tension output electrically and mechanically connected to a respective spark plug.

For a better understanding of this invention preferred embodiments will now be described with the assistance of drawings in which:

FIG. 1 illustrates a preferred embodiment of the invention when used to reduce the number of high tension components associated with conventional mechanical ignition systems,

FIG.2 illustrates a second preferred embodiment of the invention,

FIG.3 illustrates a third preferred embodiment of the invention,

FIG.4 illustrates a fifth embodiment of the invention in which the ignition system does not require breaker points,

FIG.5 illustrates a sixth embodiment of the invention,

FIG.6 illustrates how dual sparking can be incorporated into the invention, and

FIG.7 illustrates a further embodiment of the invention, and

FIG. 8 illustrates the distribution assembly for the embodiment in figure 7.

Referring to FIG. 1 there is illustrated a first embodiment of the invention in which the ignition system 1 includes a battery 2, the negative of which is connected to earth and the positive is connected to one side of the ignition switch 3. The other side of the ignition switch 3 is common to one side of the low tension coils 4, 5, 6 and 7 of the ignition coils. The other side of the low tension coils 4, 5, 6 and 7 are connected to the commutator segments 8, 9, 10 and 11 respectively. One side of the capacitors 16, 17 , 18 and 19 is connected to stationary commutator segments 8, 9, 10 and 11 respectively. The other sides of the capacitors 16, 17 , 18 and 19 are connected to earth.

The distributor arm 13 has a brush 12 which is adapted to make electrical contact (and mechanical contact) with the commutator segments 8, 9, 10 and 11. The brush 12 is connected via the distributor arm 13 to one side of the breaker contacts 14 which are opened and closed by the rotating cam 15; the other side of the breaker contacts is connected to earth. The high tension coils 20, 21 , 22 and 23 of the ignition coils are respectively connected directly to the spark plugs 24, 25, 26 and 27.

The embodiment of FIG. 1 has the advantage that the distributor means (which includes the commutator segments 8, 9, 10, 11 , distributor arm 13 and brush 12) can operate at the standard low voltage available from a battery of a vehicle (which is nominally 12 volts and at least less than 16 volts allowing for charging and discharging voltage changes) due to the brush 12 making electrical and mechanical contact with the commutator segments 8, 9, 10 and 11. Furthermore, the firing of a piston is controlled by the relative positioning of the commutator segments 8, 9, 10 and 11 with respect to the brush 12 and the opening of the breaker contacts 14. In addition, the capacitors 16, 17, 18 and 19 assist in arc suppression once the breaker contacts 14 open.

Consider the circuit of FIG. 1 in which the brush 12 attached to the distributor arm 13 is rotating in an anti-clockwise direction and has just passed the commutator segment 9 such that it is at the insulation gap between the commutator segments 9 and 8. When the brush 12 makes contact with the commutator segment 8 the piston associated with the spark plug 24 is in the approximate range of +20 or -20 degrees top dead centre. At this instance the breaker contacts 14 are closed and current flows through the low tension coil 4.

At a later time instance (when the brush has travelled slightly further in an anti¬ clockwise direction) the breaker contacts 14 open causing a back electro motive force across the low tension coil 4. Consequently, a high voltage is generated across the high tension coil 20 which provides a spark at the spark plug 24. This ignites the fuel in the cylinder and piston arrangement associated with the spark plug 24. Thus, the relative positioning of the commutator segments 8, 9, 10, 11 and the brush 12 are adapted to enable the breaker contacts 14 to. provide a spark to the desired cylinder and piston arrangement.

When the breaker contacts 14 open the capacitor 16, which is effectively connected across the commutator segment 8, brush 12 and breaker contacts 14, assists in arc suppression. However, this is an enhancement to this embodiment in that the length of the commutator segment 8 is long enough to allow the back electro motive force to be substantially minimised before the brush 12 leaves contact with this segment 8. However, in another embodiment the breaker contacts 14 close whilst the brush is still in contact with segment 8. The sequence then continues with the brush contacting commutator segment 11 , the breaker points 14 opening to provide a spark at the spark plug 27.

Referring to the second embodiment of FIG. 2 there is illustrated a further distributor means including a commutator segment 28 for providing electrical contact with the brushes 29, 30, 31 and 32. The brushes are spring loaded by the springs 33, 34, 35 and 36 to assist in a suitable electrical contact with the commutator segment 28. The brushes 29, 30, 31 and 32 are electrically connected to the low tension coils in an identical way to the embodiment illustrated in FIG. 1. The commutator segment 28 is electrically connected to the breaker contacts 37 which are closed by the rotating cam 15 and thereby connecting the commutator segment to earth. The insulator 52 provides electrical isolation to at least 3 of the four brushes at any one instance. This embodiment has the same function as that illustrated in FIG. 1. However, in this embodiment the commutator segment 28 rotates and the brushes 29, 30, 31 and 32 are stationary.

Referring to FIG. 3 there is illustrated a further embodiment in which a distributor arm 43 is electrically connected to earth by breaker points 51 which are closed by the rotating cam 50. Commutator segments 39, 40, 41 and 42 are electrically connected to low tension coils (as in FIG. 1 and FIG. 2) by the wires 47, 48,49 and 50. The brush 44 rotates and forms an electrical connection with one of the commutator segments commutator segments 39, 40, 41 and 42 or is electrically isolated by one of the insulating segments 54,

55, 56 and 57.

Referring to FIG. 4 the distributor means is similar to that of FIG. 3. However, the length of the commutator segments is reduced. In this arrangement there is no requirement for breaker points as the connection between the brush and one of the commutator segments provides current flow through one of low

tension coils. Current flow through a coil is switched off by the brush breaking contact with the respective commutator segment. Thus the length and position of each commutator segment 39, 40, 41 and 42 controls the current flow through the low tension coils 4, 5, 6 and 7, which in turn induces a high voltage into the high tension coils 20, 21 , 22, 23 to provide a spark at one of the spark plugs 24, 25, 26 or 27. The base 58 of the distributor means is attached to the advance and retard plate normally situated in a standard distributor. Consequently, as the advance and retard plate moves (rotates in an axial direction) the commutator segments move axially and therefore the firing angle is adjusted.

Referring to FIG. 5 this illustrates a disc commutator which can be attached directly to the advance and retard plate.

Referring to FIG. 6 there is illustrated a means of providing dual sparking in which the rotating cam 59 (in this case adapted to be used upon a six cylinder engine) opens and closes two sets of breaker points 60 and 61 at different times. The breaker points 59 and 60 are connected in parallel such that one side is connected to earth (in this embodiment) and the other side is connected to a common terminal 63 which in turn is connected to the distributor arm. Breaker points 60 are attached to the advance and retard plate 62. The breaker points 60 are adjusted such that they close and thereby provide a spark before the piston reaches top dead centre. However, the actual firing angle is varied by the advance and retard plate 62 movement. The breaker points 61 are positioned so that they close and therefore effect a spark when the piston is substantially at top dead centre. This arrangement in conjunction with the commutator distributor means provides two sparks per piston cycle one at approximately between 20 to 6 degrees top dead centre and one at substantially top dead centre. Thus, this provides for a means of igniting more of the fuel in the cylinder.

Now referring to Figure 7 this illustrates in a schematic manner a further embodiment wherein there is included for a multi-cylinder internal combustion spark ignition engine, a low voltage (12 volt nominal) direct current electrical supply 64, a distribution means 65 synchronously coupled through a gear and shaft connection to an engine cam shaft. The distribution means 65 are arranged to direct synchronously with the drive of the motor through a rotor arm and commutator 66 current at the low voltage of substantially 12 volts to

each of a plurality of ignition coils 67, 68, 69, 70, 71 and 72. These are, in turn, coupled through a high voltage side of the respective coil to a respective spark plug shown in representative manner at 73 for a respective cylinder for effecting a spark within the spark plug.

Fuel injection means shown in representative manner at 74 are associated with each cylinder of the engine and the distribution means 65 are arranged to, synchronously with the drive means of the engine, inject fuel into a corresponding each one of the cylinders in turn.

In this embodiment the injectors 74 are each aligned with the inlet valve of the respective cylinder and are positioned so as to direct atomised fuel into the opened inlet directly into the cylinder. The timing of this is selected so that a first charge of air has been drawn in so that the fuel drawn in afterwards lays over the air charge. Good advantage has been found can be achieved from this arrangement in terms of fuel usage pollution reduction.

The distributor 65 has a separate set of conducting segments 75 which are selectively connected to the respective injectors 74 through switches 76 and 77 which act as a throttle control. This is achieved by the segments being aligned so that with more of the segments being selected there will be a greater amount of fuel injected into the cylinder because the injectors are activated for a correspondingly greater period of time.

The rotor arm 78 is connected to the same shaft as the rotor arm for the low voltage current distribution for the ignition shown at 66. In this way accurate synchronisation is effected on an essentially fail safe basis which is a very useful feature.

Current to the rotor arm is supplied through a slip ring at 79 and 80 and a make and break contactor system is provided by the arrangement at 81. This is connected to the input side of the slip ring 79.

Referring to Fig 8 this illustrates again in a schematic way a part of the embodiment as shown in Figure 7 this being the arrangement of the distributor 65. There is accordingly a shaft 83 which is supported for rotational movement with respect to the body 84 and connected by means which are not specifically shown but which are entirely conventional to drive means by way of the cam shaft of an internal combustion engine so the shaft will rotate

correspondingly with the rotation of the engine.

A centrifugal advance arrangement is incorporated at 85 by which the relative position of the upper part of the shaft is advanced or retarded in relationship to the rotational speed of the shaft. Next at 82 there is provided a vacuum advance for controlling the relative position of the contact breaker 81 with respect to the cam 86 the vacuum being derived from the inlet manifold of the engine.

There are then shown slip rings 79 and 80 and finally the commutator arrangement for the fuel injection at 75 and the commutator arrangement for the ignition at 66. The commutator arrangement in each case includes a resiliently loaded brush assembly supported on the upper shaft 87

The arrangement shown has been found in trials conducted so far to provide improved performance for an internal combustion engine using conventional high tension distribution and conventional fuel injection. Further there are other advantages such as greater reliability in so far that the low voltage distribution is not as susceptible to moisture and general break down.