JPH0435797B2 - - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for measuring and processing signals using a single window comparator, which is supplied with the signal to be measured.

State of the Art Circuit arrangements for detecting ignition signals are generally known, for example in the case of engine measuring devices. Ignition angle and dwell angle measurement circuits used in engine measurement devices are generally of analog construction and are significantly more expensive in order to suppress oscillations in the measurement current that occur, for example, at the beginning and end of the ignition spark. Requires parts. Furthermore, even in the case of digital circuits, interference pulses can occur on the signal transmission path, for example due to fluctuations in the operating state. Conventionally, large costs have been required to detect and remove such interference pulses.

Effects of the Invention The signal measurement and processing method of the present invention has the following advantages. This means that the first correct pulse edges can be detected in both analogue and digital signals, and interfering pulses caused, for example, by damped oscillation processes and rising transient oscillation processes can be eliminated. All circuits are configured digitally,
Easy integration is therefore another advantage.

It is advantageous to convert the analog supplied measuring signal into a digital signal with a predetermined level.
In this way, any analog signal can also be processed. It is advantageous to generate an interrupt signal in the event of a zero crossing of the signal to be measured. In this way, the circuit for generating the interrupt signal can be constructed particularly easily. If only the rising edge of the pulse or only the falling edge of the pulse needs to be evaluated, it is possible to generate a mark signal only when a falling edge of the signal is additionally preceded by a predetermined period of time without an interrupt signal. It's advantageous. It is very advantageous to generate the necessary digital signals using a comparator such as: That is, a comparator is used, which outputs a signal when the signal to be measured enters a window, or whose output signal changes state with respect to a predetermined reference value. When high voltages of the input signal are expected, as occurs, for example, in the case of ignition signals, it is advantageous to provide a limiter on the input side that reduces excessively high voltages. In this way, there is no risk that subsequent elements will be destroyed by high voltage. It is likewise advantageous to provide this limiter in a voltage range within the input voltage range of the comparator with respect to the voltage value of the measured value and the comparison point.

Note that if the repetition of interrupts is rapid, it is preferable to provide a filter to prevent evaluation of the signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an apparatus implementing the signal measurement and processing method of the invention.

In FIG. 1, an input signal is fed to a limiter 1, in which transiently high voltages of the input signal are blocked. In this case, the limiter 1 is the comparison point of the measurement signal,
For example, the zero point is shifted into a range that can be received as an input signal by a downstream comparator. The output signals of the limiter 1 are supplied to a comparator 2 and a comparator 3, respectively. Comparator 2
and comparator 3 are configured into one window comparator. For example, a window discriminator manufactured by Siemens, model number TCA965, is suitable for this purpose. The comparator 2 operates to output a signal with a logic value of 1 to the output side when the input signal exceeds a predetermined voltage, and to output a signal with a logic value of 0 when the input signal exceeds a predetermined voltage. Comparator 3
sends out one pulse at the output when the signal to be measured is within a predetermined window. The output side of the comparator 2 is connected to the input side of one port of the microprocessor 4. The output of the comparator 3 is connected to the interrupt or timer input of the microprocessor 4.
As the microprocessor, for example, Motorola's model MC6801 can be used. Using a microprocessor, the desired amount can be calculated and output to the indicating device. For this purpose, the output side of the microprocessor 4 is connected to an indicating device 5.

The operation of the circuit arrangement of FIG. 1 will be explained in detail with reference to FIG. 2 in connection with the evaluation of the ignition signal.
TD as input signal instead of ignition signal
It is also possible to provide a Tacho Diagnose signal, for example a bouncy signal, or a signal with similar rising transient and damped oscillation characteristics. FIG. 2a shows the ignition signal occurring in the primary winding of the ignition coil. When the contacts of the interrupter are closed, a predetermined voltage is applied to the terminals of the primary winding of the ignition coil. When the interrupter contacts are opened, the transient vibrations that normally occur during the ignition pulse occur. This transient oscillation passes in the form of a damped sinusoidal oscillation and ends up in the so-called combustion voltage line, ie the voltage that is transferred via the burning ignition spark to the primary side of the ignition coil.
After the electrically stored energy has been almost completely converted into thermal energy by the ignition spark, the voltage dissipates according to a damped oscillatory process. At a predetermined crankshaft angle, the interrupter contacts are closed again. This ignition signal, shown in FIG. 2a, is reduced to and matched to the input voltage width of the comparators 2, 3 using a high resistance limiter circuit. The magnitude of this input voltage width is, for example, 1.5V to 4V.
A switching point or window width can be set in the comparators 2, 3 by means of resistors.
The comparison voltage of the comparator 2 is set, for example, between the maximum input voltage and the minimum input voltage, and is also the midpoint of the window of the comparator 3.

The comparator 2 forms the signal of FIG. 2b from the signal of FIG. 2a at its output. For example, all ignition voltages below OV are formed as logic 0 signals, and all ignition voltages greater than OV are formed as logic 1 signals. A signal shown in FIG. 2c is outputted to the output side of the window comparator 3, and is called an interrupt signal. This interrupt signal occurs for a short time each time the ignition signal of FIG. 2a passes through zero. The direction of zero crossing is then irrelevant. Furthermore, the mark signal generated by the microprocessor 4 is shown in FIG. 2d. The mark signal is set to a logic value of 1 if a negative edge of the ignition signal is detected without an interrupt occurring for a predetermined period of time. When the ignition signal changes toward a logical 1 without an interrupt occurring for a predetermined period of time, the mark signal is reset to a logical 0. The mark signal can be reset at two points. Generally, the mark signal is reset at the end of the combustion voltage line shown in FIG. 2d. However, if the course of the ignition process is irregular and there are disturbances, the combustion voltage characteristic curve may also not occur at all, in which case the mark signal will be closed at the second point shown in Fig. 2d. Reset at start.

Regarding the operation of the microprocessor which generates the mark signal of FIG. 2d depending on the level signal of FIG. 2b and the interrupt signal of FIG.
This will be explained in detail using the flowchart shown in the figure. As soon as the interrupt signal shown in FIG. 2c is input to the timer input side of the microprocessor 4, the program is started. First, the microprocessor memorizes the time point SP when the interrupt signal is generated in the input step 10. At the same time, level P in Figure 2b
is stored in the input step 11. In this case, level P can only take a logical value of 0 or 1. In the judgment step 12, the actual level value is compared with the immediately previous value. If these two level values are equal, the program is aborted. With this approach, short interfering pulses that trigger interrupts are filtered out. With the following configuration, the time interval from the current interrupt to the previous interrupt is calculated in the judgment step 13. This value is compared with a fixed time T. If this calculation time is shorter than a fixed time T, the evaluation process is aborted. It is advantageous if the aforementioned fixing time T is chosen to be longer than half the period of each damped oscillation process of the signal to be observed. By such a method,
Figure 2c following the start interrupt
Interrupt signals can be identified and separated. Therefore, the frequency occurring during ignition initiation is 10kHz to 40kHz
The ignition damping vibration and the damping vibration after the end of the spark combustion process with a frequency of 2 to 4 kHz cannot pass through the judgment step 13 and proceed to the judgment step 15. Second
The second and subsequent pulse of the pulse train after the end of the combustion voltage characteristic curve shown in FIG.
The judgment step 15 is not reached beyond this step. Similarly, the first pulse train that follows the first pulse in FIG. 2c therefore does not pass decision step 13 and reach decision step 15. Therefore,
When measuring the ignition signal, it is desirable to select the time T to be approximately 400 μsec. If this time condition is not met, the interrupt point of level Pn
The actual value of SPn and the actual value of the ignition point ZZPn, which will be described later, are stored as previous values for the next program execution, and then the program ends. This takes place in process step 14. In the judgment step 15, it is judged whether the actual level P indicates a logical value of 1 or not. If the actual level P does not indicate the logical value 1,
According to the judgment conditions of judgment step 12, the previous level value should be a logical value of 1. The signal to be measured therefore exhibits a falling edge at the beginning of the program currently being executed, which is the case in the left-hand branch of decision step 15 in the flowchart. However, the falling edge that occurs after a relatively long time T is
It shows the beginning of the ignition point. The current point in time SP is therefore set in process step 16 as the ignition point ZZP. In judgment step 17, mark signal MB
is set to logical zero. Immediately after switching on the circuit arrangement, the microprocessor 4 may output a logic value 1 when the circuit arrangement is not synchronized. In this case, the actual stored value is stored as the previous value in process step 14, and then the program ends. If the mark signal has a logical value of 0, the previous value at the time of interrupt is set as the closing time SWP. This takes place in process step 18. Furthermore, the mark signal is set to a logic value of 1 as shown in FIG. 2d. This is the second
This only occurs when the first falling edge occurs as shown in Figure a. In processing step 14, the value at that time is newly stored as the previous value. The original, previous value is removed from the program.

In the judgment step 15, if it is judged that the level signal Pn detected in the detection input step 11 is High, the previous value is determined by the judgment in the judgment step 12.
Pn _-1 should have been Low. Therefore, an interrupt is occurring due to the rising edge of the signal.
This time, in decision step 20, it is determined whether the mark signal MB is set to a logic value of zero. If the mark signal MB is not 0 as shown in Figure 2d,
The mark signal MB is set to 0 in a processing step 21. This generally occurs at the end of the combustion voltage line shown in FIG. 2d. In the event of a disturbance in which the combustion voltage characteristic curve is completely or only incompletely formed, the mark signal is reset to 0 at the position indicated by d in FIG. 2d, ie at the closing point of the interrupter. In calculation processing steps 22 and 23, the closing angle
SW and ignition spark combustion duration ZBD are calculated.
The closing angle SW expressed as a percentage of the unit circle is determined by the formula SW=ZZPn−SWP/ZZPn−ZZP o−, where the current ignition point is ZZPn, the closing point is SWP, and the previous ignition point is ZZP _o − _1. Calculated from ₁ . That is, the duration between closing and opening of the interrupter is divided by the total time between the two firing points. The ignition spark combustion duration ZBD is calculated from the actual interrupt time SPn and the ignition time ZZPn, and must also be confirmed in the process 24. In this case, the program is terminated by process step 14. In process step 14, the actual interrupt time, level and ignition time are stored as the immediately previous values.

If the mark signal has a logical value of 0 in the judgment step 20,
The closing point of the interrupter is detected. In this case, the time of closing of this interrupter is preceded by a normal ignition spark combustion process, and the mark signal has already been reset at the end of that ignition spark combustion process. Ignition spark combustion duration is confirmed.

The invention is summarized below. Predetermined switching (pulse)
In the signal to be measured that has side edges, oscillating processes or disturbance pulses may occur after the first correct switching (pulse) side edge (for example, decay or rise); according to the invention, such a measurement The change in the signal to be detected can be measured to detect the first correct switching (pulse) edge and the signal can be reformed (processed) free of the oscillation processes or interfering pulses as described above. In other words, the mark signal generated in the microprocessor 4 corresponds to the input signal to be measured from which vibrations or disturbances have been removed. This mark signal can be obtained by several means. First, a window comparator is provided, and this window comparator is composed of two comparators 2 and 3. At the output side of the comparator 2, a signal is formed that reproduces a predetermined level of the input signal, for example, a zero level. This signal is supplied to the microprocessor 4. An interrupt signal is formed at the output of the comparator 3, which changes the output state of the comparator 3 whenever the input signal is within a predetermined area (window). In the illustrated embodiment, this is the case, for example, if the input signal shown in FIG. 2a is within the window of the zero crossing. The signal on the output side of the second comparator 3 is
This is shown in Figure 2c. Microprocessor 4
uses the output signals of both comparators 2 and 3 as its input signals, and performs logical calculation processing and time window T setting processing to accurately switch the input signal as shown in Fig. 2d. Detect edges.

The signal measurement and processing method is used not only for the detection of ignition signals, but also for the so-called TD (Tacho Diagnose) signal obtained from transistor ignition devices, for example.
It is likewise suitable for signals which are subject to vibrations due to chatter or incorrect closing during the switching process. This is the case, for example, with digital signal lines or with electrical keys and relays. Depending on the criteria for stopping the signal evaluation, for example the time in decision step 13 and the switching conditions in decision step 15, the original signal can be detected satisfactorily.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device implementing the signal measurement and processing method of the present invention, FIG. 2 is a diagram for explaining the circuit device of FIG. 1, and FIG. 3 is a diagram showing the functions of a microprocessor. This is a flowchart for explaining. 1...Limiter, 2, 3...Comparator, 4...
...Microprocessor, 5...Instruction device.

Claims (1)

[Claims] 1. A method for measuring and processing signals using one window comparator supplied with the signal to be measured, in which the window comparator is composed of two comparators, and whenever the signal to be measured is within a predetermined region, One of the comparators 3 sends out an interrupt signal that changes the output state of the comparator, which causes the microprocessor 4 to start an interrupt process to determine whether the signal to be measured exceeds a predetermined limit value. or below, the other comparator 2 sends out a signal, and if the signal level changes without an interrupt signal being generated for a predetermined time T, the mark signal is output to the microprocessor 4.
A method for measuring and processing a signal, characterized in that if the interrupt signal is not generated for a predetermined time T and the signal level changes again, the mark signal is reset again.