JPS63308564A - Engine tachometer drive device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field The present invention relates to a drive device for an engine tachometer.

BACKGROUND ART Recently, engine revolution meters have been widely used as devices for displaying engine revolution speed. Such engine speed meters have a problem in that the display does not accurately follow changes in the engine speed due to a delay in the response of the movable parts to sudden changes in the engine speed. Therefore, in order to improve the indication response characteristics of the engine revolution meter, for example,
No. 9792 discloses a method in which an analog signal representing the engine rotational speed is obtained, and when the rate of change of this signal exceeds a predetermined value, the amplification factor of an amplifier is increased during that time to improve the transient response characteristics of the display device. has been done. however,
In such a system, it is not necessarily easy to finely change the amplification factor, and a satisfactory improvement in transient response characteristics cannot be obtained.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide an inexpensive engine tachometer drive device with good transient response characteristics.

In order to achieve this object, the engine revolution meter driving device according to the present invention detects the rate of change of an engine revolution signal representing the engine revolution number, and detects the magnitude of the detected engine revolution number signal and the engine revolution number signal. The engine tachometer is driven by a drive pulse signal consisting of a regular periodic pulse train whose pulse width changes depending on both the magnitude of the rate of change.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the configuration of this embodiment. In this embodiment, an engine tachometer drive control is performed on an engine ignition system controlled by a microcomputer. The pulse generator 1 generates two pulses A and B in response to the rotation of the engine crankshaft (not shown). The A pulse is generated once per revolution of the engine, and the B pulse is generated once per constant rotation of the crankshaft. Note that this B pulse is an engine rotation speed signal whose period changes depending on the change in engine rotation speed. These pulses are supplied to a microcomputer consisting of CPU2, ROM3 and RAM4. The CPU 2 calculates the ignition timing according to the programs stored in the ROM 3 and RAM 4 based on the supplied pulses, and supplies the flip-flop 5 with a command signal based on the calculation result. The flip-flop 5 switches the transistor 6 to supply or cut off current to the primary side of the ignition coil 7, thereby adjusting the ignition timing of the spark plug 8. The CPU 2 further calculates the supply current to the engine tachometer 9 based on the supplied pulses, supplies a command signal based on the calculation result to the drive circuit 10, and the drive circuit 10 calculates the current supplied to the engine revolution meter 9 based on the command signal from the CPU 2. The switch S is turned on to supply or cut off the current to the engine revolution meter 9.

Next, the operation of the CPU 2 will be explained. 2 to 6 are flowcharts of a control program governing the operation of the CPU 2. FIG. The program shown in FIG. 2 is executed by interrupting the main routine shown in FIG. 3 every time a B pulse is input. In the program shown in FIG. 2, first, the count value S of the stage counter is incremented by 1 (step 1). Next, the period T of the B pulse is input (step 2), and it is determined whether the stage counter value S is equal to the ignition stage count value Sig (step 3). Here, the ignition stage count value S can be read from the 1g content written in the RAM4. FIG. 3 is a flowchart of the setting program for the ignition stage count value S, in which the function value f+ (T) determined by the period T of the input B pulse is written to the RAM 4 as the ignition stage count value S. . The function g value f+(T) can be stored in advance as a data map. This program runs endlessly,
Updated values are written into the RAM 4 at any time.

If it is determined in step 3 that S=S, and 1g, it is determined that the crank angle has reached the vicinity of the ignition angle, and the ignition cutoff trigger count value ttg is set to the timing count value t (step 4 ).

The ignition cutoff trigger count value t18, like the ignition stage count value S, can be read from what is set by the function value g+(T) in the program of FIG. 3 and written to the RAM 4. Next, the set timing count value t is decremented by 1 (step 5), and the magnitude of t and O is compared (step 6), and t continues to be decremented as long as t≧0. When 1<0, it means that the ignition timing has arrived, and the energization stop command, that is, the set output is supplied to the set input terminal of the flip-flop 5 (step 7).

At this time, the output of the flip-flop 5 shifts from a high level to a low level, the transistor 6 is turned off, the current on the primary side of the ignition coil 7 is cut off, and the ignition plug 8 is ignited. On the other hand, if it is determined in step 3 that S=S is not true, the energization stage g-ji count value S. It is determined whether g is equal to the stage count value S (step 8). Here, the energization stage count value S. A value of 2 is also set in the program of FIG. 3 and written to RAM4. If it is determined in step 8 that S = S cg, the energization timing count value t is written in the RAM 4 similarly to the energization stage count value S . g is set as the timing count value t (step 9). Next, the set timing count value t is decremented by 1 (step 10), and the magnitude of t and 0 is compared (step 11).
Continue decrementing t as long as t≧0. When 1<0, it means that the energization timing has arrived, and the energization start command, ie, the reset output, is supplied to the reset input terminal of the flip-flop 5 (step 2). At this time, the output of the flip-flop 5 shifts from a low level to a high level, the transistor 6 is turned on, and current supply to the ignition coil 7 is started. On the other hand, in step 8, s
If it is determined that 0g is not equal to s, a subroutine for calculating the current value (■) to be supplied to the engine tachometer 9, which will be described next, is executed. As shown in Fig. 4, the stage count value S becomes 0 every time the A pulse is input.
is initialized to .

Next, (1) calculation subroutine will be explained. Figure 5 shows the CPU
2 is a flowchart of a calculation subroutine governing the supply current control operation to the engine tachometer 9 in Step 2.

In the program shown in FIG. 5, first, the amount of change ΔT in the period T of the input B pulse is calculated (step 21).
Then, it is determined whether the absolute value 1ΔT1 of this amount of change is larger than a predetermined value α (step 22). If it is determined in step 22 that 1ΔTl>α, the variable N is incremented by 1 and set as a new value of N (step 23), and whether or not this new value of N is larger than the predetermined value n is determined. (step 24).

If it is determined that N>77, the pulse width correction amount ΔtI of the pulse supplied to the engine tachometer is set by the function value A(ΔT, T) (step 25). The value of the function value A (ΔT, T) can be retrieved from stored map values determined by ΔT and T, for example, or
Or Figure 7(a).

1 (ΔT) for two pre-stored function values as shown in the song.
), lL2 (T), and the characteristics can be arbitrarily selected. Furthermore, if it is determined in step 24 that N>n, the value of Δtl is not newly set and is held as it was previously. On the other hand, in step 22, 1ΔTI
> If it is determined that α is not the case, the value of N is set to zero (step 26), Δt1 is also set to zero (step 27), and no correction is made. In this manner, when the periodic rate of change is larger than the predetermined value α, a correction value for the pulse width of the supply pulse is set in accordance with the magnitude of the rate of change.

On the other hand, the CPU 2 executes the program shown in FIG. 6 at regular intervals, in addition to the program shown in FIG. 5.

This program includes the B pulse interrupt in Figure 2 and the A pulse interrupt in Figure 4.
This is a lower interrupt level than a pulse interrupt, but a higher level interrupt routine than the main routine. First, the pulse width is assumed to be equal to the function value g (T) (step 31). The function value g (T) is, for example, t l =b/T
(b: constant), and the characteristics are as shown in FIG. The function value g (T) can be retrieved from pre-stored map values in the same way as the function value A (ΔT, T). Next, the value of ΔtI set by the program of FIG. 5 is added to the value of tr of the pulse width set in step 31, and is set as a new pulse width (step 32). After the P counter is reset, the value of the pulse width tI thus set is set in the P counter (step 33), and a command to energize the engine tachometer 9 is supplied to the drive circuit 10 (step 34). The P counter starts counting down from the P counter value determined by the value of the set pulse width tl (step 35). The P counter continues to count down while monitoring whether or not the P counter value is zero (step 36), and when the P counter value reaches zero, a energization stop command is issued (step 37).

Figures 9(a) to 9(a) show the pulse width control operation according to this embodiment. That is, the P counter is reset and a down count is started at regular intervals according to the change in the engine speed Ne shown in FIG. 9(a), and the pulse width of the supplied pulse is changed depending on the rate of change in the engine speed. is forced to change.

Effects of the Invention As described above, the engine tachometer drive device according to the present invention detects the rate of change of the engine speed signal representing the engine speed, and detects the magnitude of the detected engine speed signal and the engine speed. Since the engine tachometer is driven by a drive pulse signal consisting of a fixed-period pulse train whose pulse width changes depending on both the magnitude of the rate of change of the number signal, the response delay of the engine tachometer is finely and accurately controlled. corrections can be made.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an engine tachometer drive device according to the present invention, and FIGS. 2 to 6 are flowcharts of a control program constituting this embodiment.
FIG. 7 is a characteristic graph of function values A+ (Δt) and A2 (T), FIG. 8 is a characteristic graph of function value g (T), and FIG. 9 is a waveform showing the control operation in this example. It is a diagram. Explanation of symbols of main parts 1... Pulse generator - 11 = 2... CPU 3... ROM 4... RAM 5... Flip-flop 6... Transistor 7... Ignition coil 8... Spark plug 9... Engine tachometer 10... Drive circuit S... ····switch

Claims (1)

[Claims] means for generating an engine speed signal representing the engine speed; rate-of-change detection means for detecting a rate of change in the engine speed signal; An engine tachometer comprising a drive pulse signal generating means for generating a drive pulse signal consisting of a fixed periodic pulse train having a pulse width corresponding to both magnitudes, and driving the engine tachometer in accordance with the drive pulse signal. Drive device.