DE3139799A1 - Method for determining the ignition processes for internal combustion engines - Google Patents

Description

R- 17 38 4

25 - 9.1981 Ve / Hm

ROBERT BOSCH GMBH, 7000 STUTTGART 1

Method for determining the ignition processes for internal combustion engines ~

State of the art

The invention is based on a method for defining the ignition processes for internal combustion engines according to the type of the main claim. Such a method, in which short, periodic control signals of an ignition sensor arrangement a Controlling microcomputers is e.g. from DE-OS 28 51 336 known. However, the arrangement described there only works satisfactorily if at least one 8-bit microprocessor is used with at least one meter.

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Advantages of the invention

The inventive method with the characterizing Features of the main claim has the advantage over this that e.g. a commercial ^ -bit micro-calculator or microprocessor can be used without a counter. On the one hand, this results in a very simple circuit and on the other hand, a very 'small program scope is sufficient, which means there is still space for other functions, such as controller and indicator functions, are available. Still it will be a very good one Dynamics and a very precise control achieved.

The features specified in the subclaims are advantageous developments and improvements of the method specified in the main claim is possible. It is particularly advantageous to have the necessary time loops to determine the ignition point at the same time partly to determine a speed-dependent numerical value to use. Few memory spaces and program steps are required. Furthermore, these time loops can be used advantageously to determine the open time after the ignition point. It can be done in the simplest way If a constant number of time loops are used or one depending on the speed standing number, which is taken from fixed value tables depending on the determined speed-dependent numerical value can be.

drawing

An embodiment of the invention is shown in the drawing and explained in more detail in the following description. FIG. 1 shows a block diagram

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of an embodiment for carrying out the method, Figure 2 is a signal diagram to explain the effect -wise and FIG. 3 shows a flow chart to illustrate the method steps of the method according to the invention.

Description of the embodiment

In the block diagram shown, an ignition generator arrangement 10 is connected to a ^ -bit microcomputer 11, the structure of which is general prior art and in which only those components are shown for explaining the function which are useful for explaining the function. An arrangement according to DE-OS 31 09 576, for example, which periodically generates short control signals, can be used as the ignition generator. The ignition generator arrangement 10, a program control unit 13, two registers 1 k , 15 (Reg. A and Reg. B), a memory unit 16 consisting of read-only memories (ROM) and working memories (RAM) and an ignition output stage 17 are connected to a central processing unit 12 (ALU) connected. Such an ignition output stage 17 usually consists of an output stage transistor which is driven via a driver arrangement and which is connected to the primary circuit of an ignition coil. Any number of spark plugs can be arranged on the secondary side via a mechanical or electronic high-voltage distributor. Several ignition output stages can also be provided. In a manner not shown, a further number of sensors for detecting further parameters can also be connected to the central processing unit 12.

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A program corresponding to the flowchart shown in FIG. 3 is stored in the read-only memory ROM 16 and determined the work flow via the program control unit 20. The arithmetic operations are processed via the ALU 12.

The mode of operation of the exemplary embodiment shown in FIG. 1 or the process sequence is explained in the following with the aid of the signal diagram shown in FIG. 2 and with the aid of the flow diagram shown in FIG. The ignition generator arrangement 10 generates a signal sequence U10. To start the process, a point in time should first be selected during an encoder signal U10. The microcomputer program contains two time loops: a small time loop with cycle 2 and a large time loop with cycle 1. First, a small time loop with cycle 2 (method step 20) is processed and then in method step 21 it is queried whether the encoder signal U10 has ended is. If this is not the case, method steps 20 and are run through as a waiting loop until the transmitter signal U10 has ended. At this point in time, registers A and B have an 8-bit data word or two 4-bit data words that identify the calculated ignition point. In method step 22, register A is first decremented with large time loops in cycle 1 up to the value KuIl. The same then takes place with the content of register B in cycle 2 of small time loops. The ignition process then takes place in step 2A. In the case shown, register A contained the decimal number h and register B contained the decimal number 3. In this way, the ignition point can be set very precisely. In the following process step 25

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four large time loops are processed as open time (OZ) and then the ignition current is switched on again. This represents the simplest possible embodiment. If the open time is to be set as a function of the speed or other parameters, it would have to be done beforehand calculated number of time loops from one over the corresponding Parameters mentioned. Storage space can be removed and de-restructured.

The status of the flag is then queried in order to decide whether the speed should be determined (flag - 1) or calculated (flag = 0). These two processes take place alternately after the ignition time. Instead of the flag, of course, another label can also be used, which ensures the reciprocal processing of the two processes mentioned. First, however, the speed is to be determined. For this purpose, a large time loop is run through and added up in method step 27. Then, in method step 28, a query is made as to whether a new encoder signal U10 is present. Loop 27 > 28 is therefore run through until one appears. The number of time loops run through is added up, after which the flag in method step 29 is set to UuIl and the program returns to the start of the program.

Since the determined value for determining the ignition point has not changed, the process steps 20 to 26 are run through as described above. Since the flag is now equal to Hull, this becomes a method step 30 switched on, which includes the Eechenververfahren. Here, first of all, the distance two encoder signals proportional numerical value determined,

by the time loops added up in method step 27 with the four clock loops of the open time (OZ) and the content of register A, which also contains four Time loops are stored, are added. In addition -will the sealed content of register B, i.e. the small time loops, is also added. This addition can of course also be used when determining the speed by adding up of all time loops. The determined result serves as the address for the read-only memory (ROM). The value stored in the addressed address is now again taken over into the registers A and B and gives the ignition point in the two following periods before. The flag is then implemented in method step 31 and a return is made to the start of the program .

Claims (3)

25.9.1981 Ve / Hm EOBERT BOSCH GMBH5 7000 STUTTGART 1 Claims 1. J method for determining the ignition processes for internal combustion engines using a microcomputer with a small number of bits that can be processed simultaneously, in particular an It-bit microcomputer which is controlled by periodic control signals from an ignition sensor arrangement (10), with a first period a speed-dependent value is determined between two encoder signals and the ignition time is calculated therefrom in the following period, characterized in that the calculated ignition time is available in the form of at least two data words, the first being processed in coarser and the second in finer time loops at the beginning of each period and then the ignition is triggered. 2. The method according to claim 1, characterized in that to determine the speed-dependent value from the Ignition point further time loops until the following The encoder signal (U10) are counted and the result is added to the weighted sum of the time loops before the ignition point. 3. The method according to claim 1, characterized in that a definable number of time loops after the ignition point specifies the open time. H. Method according to one of the preceding claims, characterized in that in each computing period after the ignition time an address in a read-only memory (ROM) of the microcomputer (11) is addressed by the determined speed-dependent value and the address content specifies the ignition time of the next two periods.