JPS6122765B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention determines a digital basic load control variable that is non-linearly dependent on the throttle valve position of the internal combustion engine for determining the duration of the injection pulse supplied to the internal combustion engine. Regarding equipment.

The invention is based on the existence and use of an inductive generator of a certain construction and an associated electronic circuit that already exists, for example in the field of automobiles, and that this inductive generator The output quantity present as the frequency of the device is used to generate another digital output quantity that mediates the desired non-linear relationship. An induction generator consists of a coil wound on a U-shaped magnetic core made of ferromagnetic material,
In this case, a shorting ring is attached to both legs of the U-shape, which ring is movable along both legs depending on the travel path to be measured. Since the shorting ring actually changes the total magnetic flux through the U-shaped core proportionally to stroke, the inductance of the generator coil also changes proportionally to stroke. This inductance is then used as part of an electronic oscillator circuit. In the simplest case, this oscillator consists of a series circuit of a comparator with hysteresis, a generator coil whose inductance varies proportionally to the stroke, and an integrator whose output is fed back to the input terminal of the comparator. This oscillator generates a sawtooth voltage, the magnitude of the inductance determining the rise and fall times of the integrated voltage, so that the period of the output frequency changes as a function of the stroke. The circuit according to the invention uses this frequency and processes it further to produce a non-linear relationship between the throttle angle and the width of the fuel injection pulse.

Furthermore, conversion devices are known which convert the throttle angle into a frequency that has a non-linear relationship to the throttle valve angle. This known device uses a non-linear voltage divider operated by a throttle valve, which voltage divider is connected to an oscillator so as to vary the period of the output frequency linearly with respect to the throttle valve angle. . This output frequency is fed to a counter, which counter has a device for suppressing the first predetermined number of pulses that arrive. A predetermined relationship is then obtained between the oscillator frequency and the throttle valve angle. The known circuit is fairly expensive and uses a mechanical voltage divider for the stroke frequency conversion as described above; Non-linear relationships cannot occur.

In contrast, with the measures according to the invention having the features recited in the claims, the desired non-linear relationship can be formed without additional circuit outlay when evaluating the output frequency of an induction generator in practice. The advantage is that by influencing the contour of the generator, e.g. by influencing the course and extent of the legs of the U-shaped core, the desired non-linear relationship can be further approximated. be able to.

Another advantage of the invention is that the necessary zero point shift can be accomplished by setting the used subtraction counter to an initial value.

Finally, in the present invention, in order to obtain the desired non-linear relationship, no control on the generator side is necessary, i.e. the output signal of the inductive generator is simultaneously It is advantageous to be able to use

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the mechanical structure of an induction generator, which has a generator coil 1 and
This coil is wound around the base of a ferromagnetic core 2 having U-shaped legs 1a and 1b. A shorting ring 3 is disposed movably along the legs 1a and 1b, the shorting ring 3 having a travel path S
The value of the inductance L(s) of the coil 1 is determined by each position corresponding to . When such a generator is incorporated into the circuit shown in FIG. 2, the circuit as a whole constitutes an oscillator, the frequency of which is determined by the magnitude of the inductance L of the coil 1. Briefly describing the operation of such an oscillator, the output voltage of the comparator 5 connected before the coil 1 and having hysteresis characteristics increases depending on the magnitude of the inductance and therefore the position of the shorting ring. or down, with the subsequent integrator 6 integrating the generator output voltage faster the higher the voltage at the output terminal of the coil 1. When the upper threshold of the comparator is reached, the output voltage of this comparator flips to a negative value and the inductive generator 1
The output voltage of will change accordingly. A proportional relationship is obtained between the period of the alternating voltage present at the output terminal 7 of the oscillator 8 formed in this way and the travel stroke S or, in this particular case, the angle α of the throttle valve of the internal combustion engine. This relationship is shown in FIG. Since the oscillator 8 is constantly vibrating, the throttle valve position α=
Even at zero, a minimum period corresponding to the highest frequency occurs. Due to the reciprocal relationship between period and frequency, at an oscillator output voltage whose period is proportional to the stroke, the curve of frequency f with respect to the throttle valve angle α shown in FIG. 3 results.

When it is desired to use the representation of the throttle valve angle α as an input quantity in order to determine the width of the fuel injection pulse during fuel injection, there is a non-linear relationship between the stroke S or the angle α and possible digital values, e.g. the counting state. According to the characteristics of the invention, in the simplest case the frequency of the oscillator connected to the induction generator, i.e. the frequency with a period proportional to the throttle valve angle α, is required:
A counter is controlled by an oscillator within a predetermined fixed time period, in which it is converted into a number, and from the number then formed in the counter, the complement of this number is formed as an output variable.

For a more precise explanation, reference is made to FIG. 4, which shows a typical characteristic curve of an internal combustion engine, which shows the characteristic curve of the fuel injection pulse with respect to the throttle valve angle α with the rotational speed n as a parameter. It shows the width relationship. The slope of the curve shown is greatest at small angles and decreases with increasing angle α. If we divide the angle into equal amounts, we get
A relatively large quantization error occurs at small angles, and this error similarly decreases with increasing angle. In order to keep the quantization error constant over the entire range, the aforementioned non-linear relationship is required between the angle α and the digital final value generated by the invention;
When determining the desired nonlinearity, it is advantageous to look at the intermediate curve in FIG. A curve profile that is an example of such a desired setpoint curve is shown in FIG. 5 with dashed lines and has a sign. The course of the counting state Y with respect to the throttle flap angle α in the counter to which the counting frequency f of FIG. 3 is supplied, including the zero-point shift that was further carried out in FIG. 5, is shown as a solid line as a curve. Clearly, the complement of the curve corresponds approximately to the desired target curve. This complement has a frequency f within a predetermined constant time.
or by the inversion of the binary number Y, in a special embodiment according to the circuit of FIG. 7 described below.

In FIG. 7, the oscillator of FIG. 2 is indicated at 8 and provides an output frequency f with a period proportional to the stroke or angle. The output frequency reaches the counting input 10 of a subtraction counter 11 via a sampling and normalization stage 9, which does not require further explanation, to the set input 12 of which a time signal is supplied from a timing element 13. In this case, this time signal determines the width of a fixed time interval, during which the frequency f is respectively input and counted into the subtraction counter 11. The timing element 13 is 1
It can be triggered by any trigger pulse in 4. If it is assumed that the subtraction counter 10 is in a predetermined counting state at the start of the counting process, the counting state (corresponding to the number Y) obtained at the end of the counting process in each case will change as the frequency increases, i.e. Corresponding to FIG. 3, the smaller the throttle valve angle, the smaller it becomes. It is clear that the desired non-linear relationship corresponding to the curve of FIG. This initial value results in an initial counting state Yo at the start of the counting process, which is selected in a predetermined manner. Corresponding to FIG. 6, the initial value Yo changes the counting state depending on the number of digits of the counter, so that at the maximum generator frequency, and therefore when the angle α of the throttle flap equals 0, the counting state Y=0 is reached. (0000) is now occurring. Then α
By means of the minimum frequency at =90°, the subtraction counter 11 is subtracted from the initial value Yo until reaching the maximum count state (logic ``1'' occurs at all count output terminals). Further subtraction counter 11
is associated with a transfer gate 16, which transfers the counting state obtained in each case when a new counting process is started or when the final counting state is reached after a certain time interval. This number at the transfer gate 16 then corresponds in each case to a predetermined throttle valve angle α in the non-linear relationship of the curve in FIG.

If the approximation to the target curve made according to FIG. and approximations can be made. There is no need in any case to significantly "bend" and influence the geometry of the induction generator to produce the desired non-linear relationship. This is because this requires a very precise and therefore expensive manufacturing method, which can most often be realized with the relatively simple circuit described above. Otherwise, the possible measures during the digital processing of the input values, i.e. the introduction of non-linearities via a fixed value memory which is programmed in each case and read out from it in the desired manner, are also in vain. . This is because such procedures are relatively expensive and labor intensive.

In the present invention, the same induction generator as the oscillator used as the system for generating the input quantity has the advantage that it can also be used for a linear relationship, for example in an ignition system. It is also possible to use the period of the counting frequency f to control another counter between periods at increasingly higher frequencies than the counting frequency, so as to count periods at a constant frequency that are proportional to the stroke of the generated frequency. It is possible. The respective counting state is then clearly proportional to the travel stroke or the throttle valve angle α.

However, if the oscillator system 8 supplies an output signal with a frequency proportional to the stroke, then during the desired conversion into numbers in a linear relationship, the frequency is directly supplied to the counter, and the counting state of this counter is then It has a linear relationship to the mechanical input quantity, while for non-linear relationships the period can be used as described above.

[Brief explanation of the drawing]

1 shows the mechanical structure of an induction generator with a movable shorting ring; FIG. 2 is a schematic diagram of the induction generator connected to another electronic circuit element to form an oscillator; FIG. Fig. 3 is a diagram showing the frequency and period of the generator output signal with respect to the throttle valve angle α, and Fig. 4 is a typical characteristic showing the width of the fuel injection pulse with respect to the throttle valve angle with the internal combustion engine rotational speed n as a parameter. The diagram of the curve, FIG. 5, shows the counting state Y of the counter supplying the output frequency of the induction generator.
Figure 6 shows the counting state Y of the subtraction counter when the counting process is started with the initial value set during counting with the maximum and minimum frequencies.
FIG. 7 shows an example of an electronic circuit that is easily constructed to obtain a non-linear relationship between the induction generator output frequency taken from the throttle valve position and the width of the fuel injection pulse. FIG. 1... Induction generator, 8... Oscillator, 11... Subtraction counter, 13... Time element, 16... Transfer gate.

Claims (1)

[Scope of Claims] 1. A device for determining a digital basic load control variable having a non-linear relationship with a throttle valve position of an internal combustion engine for calculating the duration of an injection pulse supplied to the internal combustion engine, comprising: a An induction generator is provided with a short-circuit ring having a travel stroke proportional to the angle of the throttle valve to be measured, the period length of the output frequency f of the oscillator 8 containing the induction generator being proportional to the angle of the throttle valve. and b. A subtraction counter 11 is provided, to which the output frequency f of the oscillator 8 is fed, which subtraction counter is in the desired non-linear relationship to the respective throttle valve angle after the end of each counting process. A transfer gate 16 is provided for transferring the counting state, c A memory containing each initial value Yo is attached to the subtraction counter 11, and when starting each counting process, a memory for zero point shift is provided. Device for determining a digital basic load control variable non-linearly dependent on the throttle valve position, characterized in that the contents of the memory are transferred to a subtraction counter (11). 2. Device according to claim 1, characterized in that a timing element (13) triggered by a trigger pulse is provided, which timing element (13) determines the period for controlling the subtraction counter (11) by means of a counting frequency (f).