JPH0243015B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an electronic speed control device for a two-stroke engine suitable for, for example, a portable power generator having a two-stroke spark ignition engine (hereinafter referred to as a two-stroke engine). (Prior Art) A speed detection circuit obtains a pulse signal from the rotation of a crankshaft of a two-cycle engine and calculates a speed signal from the time between a predetermined number of counts of the pulse signal, and a speed detection circuit that calculates a speed signal from the time between a predetermined number of counts of the pulse signal, and a combination of the speed signal and a preset reference signal. Electronic speed control systems for two-stroke engines are already known, which have a control system that determines a compensation amount for a throttle valve from the deviation and brings the rotational speed into conformity with a set value. However, in the conventional configuration described above, the number of pulse counts for crankshaft rotation is constant regardless of the load and rotation speed, so if the predetermined number of pulse counts is increased, the time required to count clock pulses during low-speed rotation becomes longer. , responsiveness deteriorates.
On the other hand, if the predetermined pulse count number is reduced and the rotational speed is detected based on the time required for one rotation, the counting time will conversely become shorter during high-speed rotation, resulting in lower rotational speed detection accuracy and larger rotational speed fluctuations. Moreover, in the case of a two-stroke engine, the lower the load level, the more irregular combustion occurs, so if the rotation speed is detected from the time required for one revolution, the speed will be directly controlled based on the rotation fluctuations caused by irregular combustion. , hunting occurs. (Problems to be Solved by the Invention) In the conventional configuration described above, increasing the predetermined pulse count number increases the clock pulse count time during low speed rotation, resulting in poor responsiveness, and decreasing the predetermined pulse count number increases the clock pulse count time during low speed rotation. During rotation, there is a problem in that the detection accuracy of the rotational speed decreases and rotational speed fluctuations become large. Moreover, in the case of a two-stroke engine, the lower the load level, the more irregular combustion occurs, but in the conventional configuration described above, when irregular combustion occurs, speed control is directly performed based on rotational fluctuations due to irregular combustion. Therefore, there is a problem that hunting occurs. The present invention attempts to solve the above problems. (Means for Solving the Problems) The present invention provides a rotational speed changing device for varying the rotational speed of a two-stroke spark ignition engine, a load detection device for detecting a load on the two-stroke spark ignition engine,
a rotational speed detection device that outputs a pulse signal corresponding to the rotational speed of the two-cycle spark ignition engine; a clock pulse output means that outputs a reference clock pulse; and a clock pulse output means that counts the pulse signal from the rotational speed detection device and whose count value is The rotational speed of the two-cycle spark ignition engine is determined from the relationship between the reference clock pulse number outputted from the clock pulse output means and N until the number of clock pulses reaches N (a positive integer of N), and a rotational speed signal corresponding to the rotational speed is determined. control for generating a rotational speed signal generating means, and for generating a control signal according to a deviation between the rotational speed signal from the rotational speed signal generating means and a preset reference rotational speed signal and supplying the generated control signal to the rotational speed changing device; a signal generating means, and a predetermined value of N corresponding to the degree of irregular combustion that occurs depending on the magnitude of the load of the two-cycle spark ignition engine. An electronic speed control device for a two-stroke spark ignition engine, characterized in that the electronic speed control device includes a numerical value changing means for supplying a speed signal to the speed signal generating means to maintain the rotational speed of the two-stroke spark ignition engine at a predetermined value. (Embodiment) In FIG. 1, a pulse generator 11 detects rotation of a crankshaft of an engine 12 directly or indirectly as a pulse signal. As the pulse generator 11, for example, a signal generator using an ignition signal or an electromagnetic signal generator is adopted, and the voltage generated by an alternator connected to the engine 12 is converted into a rectangular wave for digital control using a waveform shaping circuit. It is also possible to have a configuration in which the image is formatted as follows. gate counter 1
3 receives the rotational speed signal (pulse signal) from the pulse generator 11, counts the rotational speed signal, and sends a count reset signal to the counter every count number (n) specified by the control circuit 14 (described later). It is now scheduled to be sent to the 15th. On the other hand, the oscillator 16 sends a reference clock pulse of a constant frequency to the frequency divider 17 for time measurement. The frequency divider 17 divides the reference clock pulse from the oscillator 16 into divided clock pulses of 1/n frequency based on the frequency division number (n) specified by the control circuit 14, and uses the divided clock pulses as a counter. It is now scheduled to be sent to the 15th. The counter 15 counts the divided clock pulses from the frequency divider 17, and the gate counter 13 counts the divided clock pulses from the frequency divider 17.
The count is reset at the same time as the count reset signal is received from the comparator circuit 18, and the count signal (rotational speed signal) before the reset is sent to the comparator circuit 18. Note that FIG. 2 (horizontal axis is time, vertical axis is voltage) shows the clock pulse output (a) from the oscillator 16 to the frequency divider 17, and the output from the frequency divider 17 to the counter 15.
The relationship between the output (b) of the rotation pulse from the pulse oscillator 11 to the gate counter 13 (c) is shown.
FIG. 2 shows, as an example, a case where n=3 is set by the control circuit 14, and arrow R indicates the reset timing. The comparator circuit 18 in FIG. 1 compares the speed signal input from the counter 15 with a set rotational speed signal from an external setting device 19 (described later), calculates the deviation, and calculates the throttle opening compensation amount by the drive circuit 20 ( For example, it is sent to a power transistor). More specifically, in the case of an AC power generator, the comparison circuit 18 determines the specified set frequency (rotation speed) based on the level (high or low) of the voltage input from the external setting device 19, for example. For example, when the input voltage is high, the set frequency is determined to be 50Hz, and when the input voltage is low, it is determined to be 60Hz. The external setting device 19 is formed as shown in FIG. 3, for example. In FIG. 3, two input terminals 21, 2
A DC power supply voltage is input to each of the terminals 2 and 2. One input terminal 21 has a resistor 23,
24 and a protection IC 25 to a predetermined input terminal of the comparison circuit 18. Also resistors 23, 24
One end of the changeover switch 27 is connected to the other end of the changeover switch 27, and the other end of the changeover switch 27 is grounded. Further, the resistors 23 and 24 are branched and grounded via a protection diode 28 in the opposite direction.
On the other hand, the input terminal 22 is connected between resistors 23 and 24 via a protection diode 29 in the opposite direction. The throttle opening degree compensation amount outputted from the comparator circuit 18 is outputted to the drive circuit 20 in FIG. 1 as a pulse train as shown in FIG. 4. The pulse train outputted from the comparison circuit 18 has a constant amplitude h and a constant period T, and the duration t of each pulse in the pulse train changes in accordance with the calculation result of the throttle opening compensation amount. The average voltage output to the drive circuit 20 due to this change
Va is starting to change. Drive circuit 20
Then, the average voltage Va given from the comparator circuit 18
A signal representing a change in the voltage is converted into a signal suitable for driving the driving section 26. For example, when a power transistor is used as the drive circuit 20, the energization rate of the power transistor is changed by changing the duration of the input pulse train,
This changes the average voltage of the signal to the drive section 26. The drive section 26 receives input from the drive circuit 20.
It is composed of a DC solenoid or a DC motor, and for example, the configuration shown in FIG. 5 is adopted.
In FIG. 5, the throttle valve 30 disposed in the intake passage 33 of the carburetor 32 has a disc-shaped valve body 34, and a vertical rotating shaft 35 that clamps and fixes the valve body 34 in a diametrical position. It consists of The rotating shaft 35 penetrates the wall of the carburetor 32 and projects upward, and the protruding portion of the rotating shaft 35 also serves as the center rotating shaft of the rotary solenoid 36. The case of the rotary solenoid 36 is fixed to the upper end surface of the carburetor 32 by screws 37. Further, the rotary solenoid 36 is configured to be able to rotate the rotating shaft 35 by a predetermined angle in response to changes in the input voltage. On the other hand, as shown in Fig. 1, the throttle valve 3
0 is connected to a throttle opening detector 38, which detects the opening of the throttle valve 30 as a voltage value. The detected opening signal is
The voltage change inputted to the A/D converter 39 is converted into a digital signal and inputted to the control circuit 14. The control circuit 14 outputs a count number (n) and a frequency division number (n) to the gate counter 13 and the frequency divider 17, respectively, based on the opening signal (corresponding to the engine load) from the A/D converter 39. It's becoming like that. The relationship between the engine load (throttle opening degree) and the count number (frequency division number) is determined in advance through experiments, and is determined, for example, as shown in Table 1.

[Table] The above control device is installed, for example, in an engine-equipped power generator as shown in FIG. In FIG. 6, an alternating current generator 40 is connected to the engine 12 and is directly driven by the alternating current generator 40.
can also serve as the pulse generator 11 as described above. The engine 12 and the alternator 40 are fixed to a rectangular parallelepiped pipe frame 41 via anti-vibration rubber 42 . pipe frame 4
A fuel tank 43 is fixed to the upper part of the pipe frame 41, and an operation panel 44 is attached to the upper front half of the pipe frame 41. The operation panel 44 is provided with an output terminal 45 for extracting power. Next, the operation will be explained. When the engine 12 starts, the alternating current generator 40 is started by the engine 12 and power generation begins. The electric power generated by the alternating current generator 40 is taken out from an output terminal 45 provided on the operation panel 44 in FIG. 6, and is used as electric power for various machines. On the other hand, for example, the voltage generated by the alternator 40 is used as a signal for controlling the rotation speed of the engine 12 in a waveform shaping circuit (part of the pulse generator 11 in FIG. 1).
is input. The waveform shaping circuit shapes the input voltage change into a rectangular wave for digital control and outputs it to the gate counter 13 (c in FIG. 2). The gate counter 13 counts the signal from the waveform shaping circuit based on the count number (n) specified by the control circuit 14, and sends a count reset signal (R in FIG. 2) every count number (n). Output to counter 15. On the other hand, the throttle opening signal detected by the throttle opening detector 38 in FIG.
4 is input. For example, if the opening degree of the throttle valve 30 is 7/8 (70% engine load), the control circuit 14 has a count number (n) of 3 according to the preset data shown in Table 1. , and sends a signal of n=3 to the gate count 13. A count reset signal is sent from the gate counter 13 to the counter 15 every time the count number of the signal from the pulse generator 11 to the gate counter 13 reaches three. On the other hand, from the oscillator 16, a
The constant cycle reference clock pulse shown in is applied to frequency divider 1.
7, and in the frequency divider 17, the control circuit 1
Based on the frequency division number (n=3) specified by 4, the divided clock pulse is divided into 1/3 as shown in FIG. 2b and sent to the counter 15. counter 15
Then, the signal from the frequency divider 17 is counted for each reset signal (R) from the gate counter 13,
The rotational speed signal (j) is output to the comparison circuit 18. Second
In the state shown in the figure, the rotational speed signal (j) is 3. The comparison circuit 18 inputted to the rotational speed signal calculates the deviation from the set frequency (for example, 50Hz or 60Hz) specified by the external setting device 19, based on that signal.
Calculate frequency change rate, etc. The comparison circuit 18 then sends a control value to the drive circuit 20 based on the calculation result. Here, when the changeover switch 27 in FIG. 3 is in the OFF state as shown, a high voltage is supplied to the comparator circuit 18 by the voltage input from the input terminal 21, and the comparator circuit 18 determines that the set frequency is set to, for example, 50Hz.
Therefore, the comparison circuit 18 performs calculations assuming that the set frequency is 50 Hz, and outputs a corresponding control value to the drive circuit 20 of FIG. On the other hand, switch 27
When switched to the ON state, the voltage from the input terminal 21 escapes via the changeover switch 27, so a low voltage is supplied to the comparator circuit 18, and the set frequency of the comparator circuit 18 is set to 60Hz. and outputs the corresponding control value. This switching of the changeover switch 27 can be performed not only before the start of operation, but also during operation. The control value from the comparison circuit 18 in FIG. 1 is transmitted to the drive circuit 20 as a pulse train (FIG. 4) as described above.
is output to. In the pulse train outputted from the comparison circuit 18, the duration t (FIG. 4) of each pulse changes in accordance with the calculation result of the throttle opening compensation amount. Due to this change, the average voltage Va input to the drive circuit 20 changes. For example, in Figure 4a, the pulse duration is short and therefore the average voltage
Va becomes low. In this case, as will be described later, the throttle opening degree is controlled to be small to lower the engine speed. On the other hand, in FIG. 4b, the pulse duration t is long, and therefore the average voltage Va is high. In this case, the throttle opening is controlled to be large and the engine speed is increased. By varying the pulse duration t in this way, the average voltage Va received by the drive circuit 20 is varied, thereby changing the throttle opening. The drive circuit 20 converts the signal provided from the comparison circuit 18 into a signal suitable for driving the rotary solenoid 36 (FIG. 5). The rotary solenoid 36 is driven by a signal from the drive circuit 20. When a voltage is input to the rotary solenoid 36 shown in FIG. 5, the rotating shaft 35 rotates by a predetermined angle in accordance with the magnitude of the voltage. This rotation opens and closes the throttle valve 30. By changing the degree of opening and closing of the throttle valve 30, the rotational speed of the engine 12 is maintained at a predetermined value so that a predetermined output value is obtained from the alternator 40 shown in FIG. The opening degree of the throttle valve 30 is detected as an analog value by the throttle opening degree detector 38 shown in FIG. The control circuit 14 determines a count number (n) based on the data shown in Table 1 from the information, and outputs it to the gate counter 13 and also to the frequency divider 17 as a frequency division number (n). This count number (n) is changed as appropriate as the throttle opening is changed, as shown in Table 1.
Control is performed based on the optimal count number (n) for each throttle opening. That is, when the throttle opening (engine load) is large, irregular combustion is unlikely to occur in the engine 12, and the engine rotational speed is stable. Therefore, in calculating the rotational speed of the engine, it is not necessary to use so many rotational periods; for example, when the throttle opening is 4/4, the count number (n) is determined to be 2. As a result, the speed at which the engine rotation speed is calculated by the counter 15 becomes faster, and rapid control is performed. On the other hand, if the throttle opening is small, irregular combustion will occur and the engine speed will become unstable.
Therefore, when calculating the engine speed,
It is necessary to average the rotation period using the number of cycles synchronized with the irregular combustion. For example, when the throttle opening is 1/8, the count number (n) is determined to be 6. As a result, although the speed at which the counter 15 calculates the engine speed becomes slow, accurate control becomes possible, and the engine speed control is maintained in a highly accurate and stable state. Note that at the same time that the gate counter 13 performs processing based on the designation of the count number (n) from the control circuit 14, the same number of frequency division numbers (n) is sent to the frequency divider 17, and the oscillator 16
Since the reference clock pulse from the oscillator 16 is converted into a pulse with a period of 1/n, the calculation at the counter 15 is based on the reference clock pulse from the oscillator 16 per pulse from the pulse generator 11, regardless of the throttle opening degree. This corresponds to the count number, and the computation in the comparator circuit 18 becomes simple. (Effects of the Invention) As explained above, according to the present invention, the rotation speed signal generating means counts the pulse signal from the rotation speed detection device and the count value is N.
(N is a positive integer), determines the rotational speed of the two-cycle spark ignition engine from the relationship between N and the reference clock pulse number output from the clock pulse output means, and generates a rotational speed signal corresponding to the rotational speed of the two-cycle spark ignition engine. The numerical value changing means generates a rotation speed signal according to the load detected by the load detection device using a predetermined value of N corresponding to the degree of irregular combustion that occurs depending on the magnitude of the load of the two-cycle spark ignition engine. Since the value of N can be varied according to the magnitude of the load, the value of N can be adjusted at light loads when irregular combustion (misfire) is likely to occur at partial loads, which is characteristic of two-stroke spark ignition engines. By increasing , it is possible to effectively prevent the occurrence of hunting during irregular combustion due to large fluctuations in the deviation from the set rotation speed, and achieve stable rotation speed control.At the same time, it is possible to achieve stable rotation speed control. It is possible to effectively prevent a decrease in detection accuracy during rotation and improve responsiveness. (Another Embodiment) (a) The throttle opening is not limited to the configuration in which the throttle opening is detected from the throttle valve 30 by the throttle opening detector 38;
The output from the throttle valve 30 is digitized as a value corresponding to the opening degree of the throttle valve 30, and the control circuit 14
You can also enter It is also possible to send a pulse signal corresponding to the opening degree of the throttle valve 30 directly from the comparison circuit 18 to the control circuit 14. (b) The frequency divider 17 can also be omitted. In this case, it is necessary to provide, for example, in the counter 15 or the comparator circuit 18, a dividing means for dividing the reference clock pulse count number in the counter 15 by the count number (n) from the control circuit 14.
In other words, by providing the frequency divider 17, it is possible to omit the division means which inevitably complicates the structure, thereby simplifying the structure and reducing costs. (c) Frequency divider 17, counter 15, comparison circuit 18,
It is also possible to omit the gate counter 13 and the like altogether and realize it by software using a microcomputer in the control circuit 14. Further, since the external setting device 19 is also constant at 50Hz or 60Hz in the case of a power generation device, for example, it can also be realized as a constant value within the software. (d) The present invention is not limited to being employed in a power generation device, and can be used as an electronic speed control device for a general two-stroke engine.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the electronic speed control device according to the present invention, Fig. 2 is a graph showing the relationship between each pulse signal for calculating the rotational speed signal, Fig. 3 is a circuit diagram of the external setting device, and Fig. 4 is A graph showing the output waveform from the comparison circuit, FIG. 5 is a perspective partial view of the throttle valve portion, and FIG. 6 is a partially cutaway front view of the alternating current generator. 12...2 cycle engine, 15...
Counter (part of speed detection circuit), 18... Comparison circuit (part of control device), 30... Throttle valve.

Claims (1)

[Claims] 1. A rotation speed changing device that varies the rotation speed of the two-cycle spark ignition engine, a load detection device that detects the load of the two-cycle spark ignition engine, and outputs a pulse signal according to the rotation speed of the two-cycle spark ignition engine. a rotation speed detection device that outputs a reference clock pulse, a clock pulse output means that outputs a reference clock pulse; and a clock pulse output means that counts pulse signals from the rotation speed detection device and outputs the clock pulse until the count value reaches N (N is a positive integer). a rotational speed signal generating means for determining the rotational speed of the two-cycle spark ignition engine from the relationship between the reference clock pulse number outputted from the outputting means and N and generating a rotational speed signal corresponding thereto; control signal generating means for generating a control signal according to the deviation between the rotational speed signal and a preset reference rotational speed signal and supplying the generated control signal to the rotational speed changing device; and a numerical value changing means for supplying a predetermined value of N to the rotational speed signal generating means in accordance with the load detected by the load detection device, the value of N being predetermined in accordance with the degree of irregular combustion that occurs, 1. An electronic speed control device for a two-cycle spark ignition engine, characterized in that the rotational speed of the cycle spark ignition engine is maintained at a predetermined value.