EP1045985A1

EP1045985A1 - Method and device for regulating power in ignition systems with a primary-side short-circuitiing switch

Info

Publication number: EP1045985A1
Application number: EP99962038A
Authority: EP
Inventors: Markus Ketterer; Klaus-Juergen Wald; Achim Guenther; Juergen Foerster
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-10-26
Filing date: 1999-10-26
Publication date: 2000-10-25
Anticipated expiration: 2019-10-26
Also published as: JP2002528675A; KR20010033597A; DE59908952D1; US6298837B1; DE19849258A1; EP1045985B1; WO2000025021A1

Abstract

Disclosed is a method and a device for regulating power in an ignition system for an internal combustion engine. The inventive device comprises an ignition coil or an ignition transformer with a primary and second winding, whereby the primary winding can be short-circuited by means of a switch (known as a short-circuiting switch) and an ionic flow can be measured by the secondary winding using one or several spark plugs. The primary current is measured in the short-circuiting phase of the short-circuiting switch using appropriate means and transmitted to the control unit. When the short-circuiting switch is actuated, the measured variable is processed in the form of a function or filtering in the control unit to form a characteristic which is used to enable power to be regulated according to time and closing angle.

Description

Method and device for energy regulation

Ignition systems with primary-side short-circuit switches

State of the art

The invention relates to an ignition system for

Internal combustion engines with a primary short-circuit switch that short-circuits the primary side of the ignition coil. Both so-called single spark coils, in each case one spark plug being assigned to an ignition coil, and double spark coils, in each of which two spark plugs are assigned to one ignition coil, can be used. Other ignition systems are also conceivable which have a short-circuit switch on the primary side. In the following, only the single spark coil will be considered, since the procedure can be applied analogously to double spark coils.

By setting up a primary side

Short circuit switch initiates the spark end in a controlled manner.

The method is therefore based on the ignition system with a shortened spark duration, as is known from DE 196 49 278. The method according to the invention can also be used with others

Ignition systems are used which use other means, for example npn transistors or thyristors, to shorten the ignition sparks via a short circuit on the primary side. An ion current measurement can be coupled to the ignition system, as is known, for example, from DE 38 83 009 T2, which measures the ion current in the combustion chamber via the secondary side of the ignition coil or the ignition transformer by means of the spark plug.

The process of switching off the ignition spark itself takes a certain amount of time, which under certain circumstances can be disruptive for the ion current measurement, and moreover the ignition coil or the ignition transformer and the short-circuit switch are unnecessarily heated by the residual energy.

Against this background, the object of the invention is

- minimize disturbances caused by the cut-off current on the ion current measurement,

- reduce the waste heat in the short-circuit switch and the ignition transformer,

- keep the electrode wear small and

- to ensure that the spark is switched off safely and quickly.

This object is achieved with the features of the independent claims. Advantageous developments of the invention are the subject of the dependent claims.

The invention does not necessarily have to be connected to a detection of the ion current, but it offers many advantages in connection with an ion current measurement.

With the solution according to the invention of the above-mentioned problems, a method suitable for series production is presented, which among other things facilitates the feasibility of ion current measurement.

The solution according to the invention overcomes the disadvantages mentioned. By determining a characteristic proportional to the residual energy a controlled variable is available for energy control via the closing time or the closing angle.

According to the invention, there is a method for energy control on an ignition system for an internal combustion engine with an ignition coil forming the ignition voltage, having a primary and a secondary winding, or an ignition transformer, the primary winding of which can be short-circuited by means of a switch, called a short-circuit switch, and by means of its secondary winding using one or more spark plugs an ion current can be measured, in which the primary current in the short-circuit phase of the short-circuit switch is measured using a suitable means and transmitted to the control unit, the measured variable after actuation of the short-circuit switch in the form of a function or filtering in the control unit

Processed feature and with the obtained feature an energy control over closing time or closing angle is built.

The closing time or the closing angle is reduced if the feature indicates too much residual energy. If the feature indicates that the residual energy is too low, the closing time or the closing angle is extended.

In one embodiment, the maximum of the primary current is used immediately after reaching the end of the spark as a feature proportional to the residual energy for energy control via the closing time or closing angle.

The drain-source resistance of the short-circuit switch, which is designed as a field-effect transistor, can be used as the means for measuring the primary current.

Alternatively, the primary current I _s is measured via a resistor in the short-circuit. In one embodiment, the regulation of the energy via closing time or closing angle can be hidden in non-stationary operating points.

Furthermore, the regulation of the energy via closing time or closing angle can take place in such a way that the energy can only be varied in a certain time window or angle window, which is limited by a lower and an upper limit.

The limits of the closing time or the closing angle can be controlled in a map, the map depending at least on load L and / or speed n and being stored, for example, in the control unit.

Furthermore, in order to master dynamic processes, the map can be divided into map areas, the current closing time or closing angle values being saved when leaving a map area, and the values previously stored being used as initial values of the control when the map area is re-entered.

In the following an embodiment of the invention is explained with reference to the figures.

Figure 1 discloses an embodiment of an inductive ignition system with energy control.

2 contains signal images of the current I _s in the

Primary winding of the ignition coil in a time correlation with a closing angle signal and a signal for controlling a spark limit switch.

3 shows an exemplary embodiment of the method according to the invention. The ignition system consists, for example, of previously known, state-of-the-art components: ignition coil 1, ignition transistor 2 and spark plug 5, it being irrelevant whether a switch-on spark suppression diode D is in series with the secondary winding L _{2 of} the ignition coil 1 or not.

In series with the ignition coil, a means 3 for ion current measurement can be attached to the low-voltage end of the secondary winding L ₂ , which forms the circuit node 3.1 with the ignition coil 1.

The primary side of the ignition coil 1 can be short-circuited via the short-circuit switch 4. The short-circuit switch 4 is advantageously designed as a field effect transistor. It forms the circuit node 5 with the ignition transistor 2 and the ignition coil 1.

In the short circuit I _B means is further incorporated for measuring the short-circuit current, which is executed in the example of Figure 1 as the measuring resistor. 7 The measuring resistor 7 forms the circuit node 6 with the short-circuit switch 4 and the circuit node 8 with the ignition coil 1.

The battery voltage U _bat for supplying the ignition coils can be fed in either at the circuit node 6 or at the circuit node 8.

Another easy-to-implement technical variant is the possibility of using the path resistance of the short-circuit switch as a measuring resistor. As a result, circuit nodes 8 and 6 coincide. The signal of the short-circuit current is passed on to the control unit 10 by the measuring means via the signal line 9. A feature is obtained in the control unit 10 via a function or feature formation. The closing time of the ignition transistor is varied depending on this feature. The new choice of the closing time is made available to the ignition transistor 2 via the signal line 11. The short-circuit switch 4 is operated by the control unit 10 via the signal line 12. The 10 control unit 10 receives further signals

Operating parameters of the engine supplied. Examples of such operating parameters are speed n and intake air quantity L. which are provided by sensors 12 and 13.

15 Fig. 2 shows the timing of various signals. First, the system works with a long closing time of the ignition transistor 2. The closing time t _x is output by the control unit. After the time t _x , the ignition transistor 2 is switched to high resistance and the ignition spark

20 comes about. The desired spark end is the

Short-circuit switch 4 closed and the spark end is initiated. The primary current rises to its maximum value very quickly and then decays exponentially in time t ₂ . The energy that is still available at the end of the spark

25 is dissipated in the resistors of the primary circuit. The primary current monitoring supplies the current short-circuit current via the signal line 9. The maximum of the short-circuit current can be according to the formula

L 30 inductance of the primary winding of the ignition coil I _s short-circuit current (see FIG. 1)

I, maximum of the short-circuit current be converted into the corresponding excess residual energy.

The system's energy balance is as follows:

'

E _pnm energy introduced on the _primary side

E _Funkaιk0pf Energy that is lost in the spark head

E _Spark energy The energy required for sparking

E _Resl Energy that is still available when the short-circuit _switch is closed

10 is available and converted into thermal energy.

The energy introduced on the primary side is consumed as follows: First, depending on the ignition voltage requirement, a different amount of energy is discharged in the spark head. After that

15, depending on the burning voltage requirement, a different amount of energy is required during the spark burning. Additional losses occur in the windings and iron circuits of the ignition coil during this process. The energy in the spark head is heavily dependent on the load and the ignition angle, but the energy for that

Sparking is from the load and also from the

Turbulence in the combustion chamber dependent. Overall, the energy requirement for the ignition spark is dependent on the load, ignition angle and speed. In addition, the energy requirement is subject to statistical fluctuations, so that for the control

25 only a filtered feature based on the short-circuit current can be used.

The basis of the regulation is the detection of the residual energy shortly after reaching the required spark end and the conversion 30 by the control unit 6 into a residual energy proportional

Characteristic. If there is still sufficient residual energy, the closing angle or the closing time at the same operating point will be reduced. This cannot be done immediately, so that low-pass filtering, for example, with the recorded values or averaging is carried out within the control unit. Conversely, if the at least required residual energy is no longer available, the closing time or the closing angle is increased.

The resistance for primary current monitoring is advantageously placed in a branch of the circuit which has no connection to the circuit node 2 in order to protect it from unnecessarily high voltages.

Another variant is to use the path resistance of the short-circuit switch, which is designed as a field effect transistor (FET), as a measuring resistor.

3 illustrates the control. The activation of the short-circuit switch 4 in step 1 is followed by the detection of the primary current (short-circuit current) in step 2. Step 3 symbolizes the formation of a characteristic or measure for the residual energy as a function of the primary current. The feature formation includes filtering or averaging. In step 4, the residual energy is regulated to a predetermined target value.

For this purpose, as shown in steps 4.1 to 4.3, the feature formed in step 3 can be compared with a threshold value.

After step 4.2, the closing time or the closing angle is increased when the feature exceeds the threshold and thus indicates a sufficiently large residual energy. Otherwise, the closing time or the closing angle is increased in step 4.3.

Claims

claims

1.Method for energy control on an ignition system for an internal combustion engine with an ignition coil forming the ignition voltage, a primary and a secondary winding having an ignition coil or ignition transformer, the primary winding of which can be short-circuited by means of a switch, called a short-circuit switch, and by means of the secondary winding of which one or more spark plugs are used Ion current can be measured, characterized in that the primary current in the short-circuit phase of the short-circuit switch is measured using a suitable means and transmitted to the control unit, the measured variable after actuation of the short-circuit switch in the form of a function or filtering in the control unit is processed into a feature and with the feature obtained an energy control over closing time or closing angle is established.

2. The method according to the main claim 1, characterized in that the closing time or the closing angle is shortened if the feature indicates an excessive residual energy or that the closing time or the closing angle is extended if the feature indicates an insufficient residual energy.

3. The method according to the main claim 1 and 2, characterized in that the maximum of the primary current immediately after reaching the end of the spark as residual energy proportional Feature for energy control via closing time or closing angle is used.

4. The method according to claims 1, 2 and 3, characterized in that the means for measuring the primary current is the drain-source resistance of the short-circuit switch, which is designed as a field effect transistor.

5. The method according to claims 1, 2 and 3, characterized in that the means for measuring the primary current I _{s is} a resistor in the short circuit.

6. The method according to any one of the above claims, characterized in that the regulation of the energy via closing time or closing angle can be hidden in unsteady operating points.

7. The method according to any one of the above claims, characterized in that the regulation of the energy over closing time or closing angle can only be varied in a certain time window or angular window, which is limited by a lower and upper bound.

8. The method according to claim 7, characterized in that the limits of the closing time or the closing angle are map-controlled, which depends at least on load or speed and is stored, for example, in the control unit.

9. The method as claimed in one of the preceding claims, characterized in that the control map is subdivided into characteristic map areas in order to master dynamic processes, and the current closing time or closing angle values are stored when leaving a map area and when they re-enter the map Map areas the adapted values are used as initial values of the control.

10. Apparatus for energy control on an ignition system for an internal combustion engine with an ignition coil forming the ignition voltage, a primary and a secondary winding having an ignition coil or ignition transformer, the primary winding of which can be short-circuited by means of a switch, called a short-circuit switch, and by means of its secondary winding using one or more spark plugs Ion current can be measured, characterized in that the primary current in the short-circuit phase of the short-circuit switch is measured using a suitable means and transmitted to the control unit, the measured variable after actuation of the short-circuit switch in the form of a function or filtering in the control unit is processed into a feature and with the feature obtained an energy control over closing time or closing angle is established.

11. The device according to the main claim 1, characterized in that the closing time or the closing angle is shortened if the feature indicates too much residual energy or that the closing time or the closing angle is extended if the feature indicates too little residual energy.

12. The device according to the main claim 1 and 2, characterized in that the maximum of the primary current immediately after reaching the end of the spark as residual energy proportional

Feature for energy control via closing time or closing angle is used.

13. Device according to claims 1, 2 and 3, characterized in that the means for measuring the primary current Drain-source resistance of the short-circuit switch, which is designed as a field effect transistor.

14. Device according to claims 1, 2 and 3, characterized in that the means for measuring the primary current I _{s is} a resistor in the short circuit.

15. Device according to one of the above claims, characterized in that the regulation of the energy via closing time or closing angle can be hidden in transient operating points.

16. Device according to one of the above claims, characterized in that the regulation of the energy over closing time or closing angle can only be varied in a certain time window or angular window, which is limited by a lower and an upper barrier.

17. The apparatus according to claim 7, characterized in that the limits of the closing time or the closing angle are map-controlled, which depends at least on load or speed and is stored, for example, in the control unit.

18. Device according to one of the preceding claims, characterized in that the map is subdivided into characteristic map areas for mastering dynamic processes and the current closing time or closing angle values are stored when leaving a map area and the adapted values are used as initial values of the control when the map areas are re-entered.