DE2050121A1 - Ignition generator for capacitor ignition systems of internal combustion engines - Google Patents

Description

R. 55 Ws / Ch
7-10.70

Attachment to

Patent «ö4

registration

ROBERT BOSCH GMBH, 7 Stuttgart, Germany

Ignition generator for capacitor ignition systems of internal combustion engines

The invention relates to an ignition generator for capacitor ignition systems for the operation of internal combustion engines, which has a fixed, U-shaped iron core with a charging winding for Charging of an ignition capacitor and for controlling a contactless switch at the ignition point as well as rotating contains permanent magnets provided with pole pieces.

It is known that two-stroke internal combustion engines can be made backflow-proof by special measures on the ignition system. but Even in the case of internal combustion engines that are not safe to return, the ignition system is designed so that the machine only operates at a fixed one Direction of rotation reaches its full capacity as the

. '-2-209817 / 0375

Robert Bosch GmbH '' p_ R 55 Ws / Lm

Stuttgart

Ignition point in the wrong direction of rotation into an unfavorable one Range of the piston position in the cylinder of the internal combustion engine falls.

But now it is useful to use two-stroke internal combustion engines to work in one or the other direction of rotation for different areas of application. E.g. With lawnmowers, the wear of the cutting blades is reduced by half if the blades alternate in both directions of rotation cut · In this case, however, the internal combustion engine must deliver its full power in both directions of rotation, which is not possible with the known ignition systems of the type described above.

The invention is based on the object of the magnetic To design the ignition generator of an ignition system so that the internal combustion engine achieves full power in both directions of rotation by the voltage required to reverse a contactless switch in one for both directions of rotation defined, favorable ignition point in the charging winding of the ignition generator is induced.

Permanent magnets

According to the invention, this is achieved by two! For clockwise and counterclockwise rotation of the internal combustion engine reached by one on their Angle relative to the central axis in the circumferential direction relative to one another are offset, which is twice as large as the ignition angle plus the control angle for the contactless switch.

The details of the invention are described in more detail using an exemplary embodiment shown in the drawing. Ea aeigen:

Pig · 1 an ignition generator with two in the circumferential direction Staggered permanent magnets and one connected to the charging winding Condenser ignition system and

-3- 209817/0375

Robert Bosch GmbH _ * R.55 Vs / Lm

Stuttgart ""

1 shows a diagram of the course of the voltages < ^1T on the charging winding and on the capacitor

and at the resistance of the ignition system according to Fig.

A magnetic ignition generator for the ignition system of a single-cylinder two-stroke engine is denoted by 10 in FIG. It has a fixed, U-shaped iron core 11 on its Leg: 11a a charging winding 12 is attached, which charges a capacitor 14 via a diode 13. The capacitor 14 is discharged through the primary winding 15a of an ignition coil 15, when a thyristor 16 in the discharge circuit becomes conductive when a control voltage is applied at the time of ignition. This voltage is taken from a resistor 17 which is connected to the connection 12a of the charging winding 12 and with the capacitor 14 is in series. As a result of the capacitor discharge via the primary winding 15a of the ignition coil 15, in its secondary winding 15b induces a high voltage pulse, which results in an ignition spark on a spark plug 18 connected to it. The one for charging the capacitor 14 voltage half-waves of the charging winding 12 that are not required are passed through the resistor 17 and another diode 19, on the one hand with the connection 12b of the charging winding 12 and on the other hand with the line 20 between the capacitor 14 and the resistor 17 is connected.

The ignition generator is also equipped with two rotating permanent magnets 21 and 22, which are circumferentially about an angle <? C, based on their central axes χ and y, of approximately 65 ° are offset from one another. The permanent magnets 21 and 22 are magnetized in the same direction and each with their Pole pieces 23 and 24 arranged at the ends are cast in a flywheel 25 made of non-magnetic material, which is not of the non-magnetic material internal combustion engine shown is driven. The pole shoes 23 and 24 are connected to the internal combustion engine when the engine is running Legs 11a and 11b of the iron core 11 moved past, the magnetic flux emanating from the permanent magnets 21 and 22 in each case in the iron core 11 rises to a maximum value and then falls back to zero.

209817/0375 _Λ

Robert Bosch GmbH . R. 55 Ws / Ch

The change in flux in the iron core 11 induces a voltage u ^ in the charging winding 12, which is shown in FIG. 2 by a solid line on the time axis t of the diagram. The capacitor 14 is charged with the positive charging half-wave. The capacitor _{voltage u c} shown by a dashed line corresponds to the peak value of the charging voltage u ^ at the end of the charging process. The current flowing through the resistor 17 due to the charging voltage Ur causes a voltage drop here, which is fed to the thyristor 16 as a control voltage "Uq", which is shown by a dash-dotted line and measured from the cathode of the thyristor 16. At the ignition point Zzp reaches the Control voltage Uq ₊ . The response voltage U of the thyristor 16 and offset

Οι &

him in the conductive state. The capacitor 14- now discharges through the primary winding 15a and in the secondary winding 15b thereby induces a high voltage pulse which is transmitted to the Spark plug 18 results in an ignition spark.

In order to ensure the full power of the internal combustion engine for both directions of rotation, an ignition angle il · ' of 20 ° is specified in the exemplary embodiment, ie ignition takes place 20 ° before top dead center (VT) of the cylinder (not shown).

angle ο
bens. Furthermore, a control β must be taken into account, which results from the fact that the control voltage u ". the response voltage is only reached when the magnetic flux in the iron core 11 decreases.

Since the chained with the Ladewickiung 12 flow due to the magnetic scattering is not exactly the same in both directions of rotation, clockwise rotation results in an attack angle

β of 14 ° and a control angle fS van for counter-clockwise rotation. 11 °. Fig. 1 shows the arrangement of the iron core 11 and the permanent magnets 21 and 22 with a piston position in top dead center. There the Daueimag ^ne * 21 effective in clockwise rotation is offset to the right with respect to the central axis ζ of the iron core 11 by the ignition angle ff " and the control angle ß , while the permanent magnet 22 effective in anti-clockwise rotation around the ignition

209817/0375

Bcvbert Boscn GmbH -5-

* Τή * waä. den -Änsteiie: rw ± nfcel yÖ 'is offset to the left.

For the WiniDBl ^ C, with the two magnets 21 and 22 facing each other Xfialasfrieiitmig are offset, therefore results for the

the equation;
= 2X20 ° + 14 ° + 11 ° °

Neglecting the different scatter results in si-cli for the equation:

2 (J ^ + jf) = 2x (20 + 14) ° = 68 °

Claims (1)

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