JP3302438B2 - Rotation speed detection device, overspeed prevention device and ignition device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detecting device which can electrically determine a rotation speed of a rotating device and determine that a predetermined rotation speed has been reached. It is suitable to be mounted on an ignition device or the like and used as an overspeed prevention device capable of preventing overspeed of the engine.

[0002]

2. Description of the Related Art Some devices for detecting the number of revolutions of a rotating device such as an engine and keeping the number of revolutions within a certain range, or issuing a warning when the number of revolutions exceeds or falls below a predetermined number of revolutions are known. Things have been realized. As these devices, devices that are linked to a tachometer, devices that determine the synchronization between a timer using an integrating circuit or the like and an ignition signal of an engine, and the like are generally used. Then, the rotation speed is determined by these devices. For example, when the rotation speed is excessively increased, control such as delaying the ignition timing to suppress the increase in the rotation speed is performed.

[0003]

In recent years, despite the increasing number of additional functions in engines and the like, it has been desired to reduce the installation space, and the installation space of the engine itself is limited. For many reasons, there is a demand for smaller and lighter control devices. In addition, as engines and the like have become more sophisticated, there is also a demand for improved reliability of control and protection functions. One problem to meet these demands is to improve the function related to engine overspeed prevention. That is,
Detecting the number of rotations via an external device that works in conjunction with a conventional tachometer requires a connection cable to the external device, which requires installation space and other problems. Also depends. Further, in a device that compares a pulse output from a timer or the like with an ignition signal of an engine or a signal based on rotation, the waveform of the signal based on rotation is poor in stability, and comparison between signals is not prepared. It is necessary to add a circuit for waveform shaping. Further, the configuration of the constant current type charging / discharging circuit required for the timer or the like has a large effect on the cost of the control device.

Accordingly, in the present invention, in view of the above problems, it is easy to incorporate the control device into a control device,
It is intended to achieve a rotation speed of detectable detector rich.

[0005]

In order to solve the above-mentioned problems, in the present invention, the rotational speed of an engine or the like is determined using a plurality of monostable circuits having different time constants. That is, the rotation speed detecting apparatus according to the present invention, the rotation
Trigger that generates a trigger signal according to the rotation speed of the device
A signal generating means, having a first time constant element,
-In response to the arrival of the signal, within the period following the trigger signal
The first pulse signal having a pulse width corresponding to the preceding cycle
First period / pulse width conversion means for outputting,
A second time constant element different from the time constant element;
Subsequent period of the trigger signal triggered by the arrival of the rigger signal
Within the second pulse signal having a pulse width corresponding to the preceding period
Second period / pulse width conversion means for outputting a signal,
High-low two logic of the first pulse signal and the second pulse signal
Logical operation means for executing a predetermined operation of and outputting a logical result
And the first speed is increased or decreased by increasing or decreasing the rotation speed.
The trailing edge of the pulse width of the pulse signal is the pulse width of the second pulse signal.
The first and second time constants are required so as to cross the trailing edge of the loose width.
It characterized by comprising setting the element.

[0006] The over-rotation prevention device according to the present invention is characterized in that
It is characterized by using a rotation speed detecting device .

Further, a voltage generator for inducing a primary current of an ignition coil for supplying an ignition voltage for an ignition plug from a rotating operation of a rotor of the flywheel magneto, and a control unit capable of controlling the primary current are provided. In the ignition device, a trigger signal corresponding to the rotation speed of the rotating device is generated.
Generating a trigger signal generating means and a first time constant element
The trigger signal when the trigger signal arrives.
In the subsequent period of the signal,
A first cycle / pulse width converter that outputs one pulse signal
Step and a second time constant element different from the first time constant element
The trigger is triggered by the arrival of the trigger signal.
-The pulse width according to the preceding cycle within the following cycle of the signal
Output the second pulse signal of the second period / pulse width
Conversion means, the first pulse signal and the second pulse signal.
Performs a high-low logic operation with the signal and outputs the logic result
Logic operation means for increasing or decreasing the rotation speed
As a result, the trailing edge of the pulse width of the first pulse signal is
The first and second signals so as to cross the pulse width trailing edge of the first pulse signal.
Made by setting the beauty second time constant element, as the control unit, wherein said an adjustable ignition timing control unit controlling timing of the primary current based on the logical result.

[0008]

In the rotation speed detecting device according to the present invention, for example,
For example, when the rotation speed reaches a certain upper limit, the first
The trailing edge of the pulse width of the pulse signal is the pulse width of the second pulse signal.
Because it crosses the trailing edge, the logical operator
Since the logical result of the stage changes,
It is possible to detect that the number of turns has reached the upper limit. Ma
By changing the first and second time constant elements,
It can also be detected that the number of turns has reached the lower limit. No.
Triggered by first and second period / pulse width conversion means
The first and second pulse widths of the binary logic as the preceding period of the signal
Can be time-compressed and converted in the subsequent cycle as
On a time axis that should be considered especially in observation or measurement.
Transformation can be assured of homogeneity, high reliability,
Setting can be used for relative binary logic operation between data widths.
Avoid introducing delicate and unreliable absolute reference values
The rotation speed has reached the upper or lower limit.
Can be determined. In particular, for power supply voltage fluctuations and temperature changes
The fluctuation characteristics of both pulse widths are almost the same, and the absolute standard
Since the correlation with the value fluctuation does not need to be considered, a high temperature compensation
Compensation performance and high reliability are obtained.

[0009]

[0010]

[0011]

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

FIG. 1 shows the configuration of an ignition device having an overspeed prevention function according to this embodiment. Main ignition device 10
Is a device for igniting the plug 12 using the voltage induced in the ignition coil 21 through the primary coil 22 from the rotation operation of the magnet set in the flywheel 11 of the engine, and a voltage generator for generating an induced voltage 20,
The control unit 30 controls the voltage generation unit 20, and further includes an overspeed prevention unit 40 that inputs an overspeed state of the engine to the control unit 30. The voltage generator 20 includes a primary coil 22 whose voltage is induced by the flywheel 11 with a magnet, and an ignition coil 21 whose high voltage for the spark plug 12 is induced by the primary coil 22. The voltage generated in the primary coil 22 is applied to a semiconductor switch 23 composed of an npn-type transistor,
Downstream of the semiconductor switch 23, a detection resistor 26 for outputting a trigger signal is connected in series with the semiconductor switch 23. The voltage generated in the primary coil 22 is applied to a base resistor 24 provided in parallel with the semiconductor switch 23, and a switching element 25 is connected in series with the base resistor 24. Since the base resistor 24 is connected to the base of the semiconductor switch 23, the voltage generated in the primary coil 22 is applied to the base resistor 24 when the switching element 25 is in the open state, and exceeds the threshold voltage of the semiconductor switch 23. , Semiconductor switch 2
3 conducts. Further, the voltage generated in the primary coil 22 is also applied to the control unit 30. When the voltage generated in the primary coil 22 takes the maximum value, the control unit 30 detects this voltage and turns on the switching element 25. State. As a result, a current flows through the base resistor 24 and the base voltage of the semiconductor switch 23 decreases.
Is turned off, and the primary current flowing through the primary coil 22 is cut off. Therefore, a high voltage is generated in the ignition coil 21, and the ignition is performed by applying the high voltage to the plug 12.

The ignition device 10 of the present embodiment is further provided with an overspeed prevention unit 40 for detecting overspeed of the engine. The over-speed prevention circuit 40 includes two monostable circuits 41 and 42 and a comparison circuit 43 to which outputs from the monostable circuits 41 and 42 are input. It is input to the control unit 30. When the one-shot trigger signals are input to the input terminals P1 and P3 of the respective circuits, the monostable circuits 41 and 42 shift from the stable state to the metastable state, and after a predetermined duration, enter the stable state. This is the circuit that returns. In this metastable state, since the output voltages appearing at the output terminals P2 and P4 of the respective circuits are different from those in the stable state, a pulse signal having a pulse duration is output. As such a monostable circuit, many circuits generally called a one-shot type multivibrator or a monostable circuit can be used. For example, the circuit can be realized by using a circuit as shown in FIG. it can.

The monostable circuit 45 shown in FIG. 2 is a circuit including two transistor switches 46a and 46b. When a trigger signal is input from the input terminal Pi, the transistor 46a is turned on, thereby discharging the capacitor 47, and the transistor 46b is turned off, so that a high-potential signal appears at the output terminal Po. This metastable state continues until the discharge from the capacitor 47 ends, and when the transistor 46b is turned off thereafter, the output terminal Po returns to a stable state in which the output terminal Po has a low potential. Therefore, the monostable circuit 4
5, when a one-shot trigger signal is input, a pulse signal is output from the output terminal Po with the duration W of discharging the capacitance 47 from the discharge path formed by the resistor 48 and the transistor 46 a. You. The duration W is determined by the capacity 47 and the resistance 48 and the capacity 4
7 is determined by the charge amount. That is, the charging time via the resistor 49 after returning to the stable state varies depending on the size of the capacitor 47. Therefore, when the capacity 47 is large, the charging time becomes long, and when the next trigger signal is input before the battery is not charged to the predetermined level, the continuous time W is shortened. The monostable circuit 45 includes a capacitor 47, a resistor 48,
By adjusting the values of 9 respectively, it is possible to relatively easily control the time constants such as the pulse duration W and the charging time.

FIG. 3 shows the operation of the overspeed prevention section 40 used in the ignition device 10. The over-rotation prevention unit 40 of this example includes a monostable circuit 41 having a large capacity for determining a time constant, a monostable circuit 42 having a small capacity, and a signal from the monostable circuits 41 and 42. And a comparison circuit 43 that outputs a signal based on the logical table shown in FIG.

[0016]

[Table 1]

First, a trigger signal proportional to the engine speed is input to the input terminals P1 and P3 of the monostable circuits 41 and 42 from time t1. This trigger signal is supplied from a detection resistor 26 connected in series with the semiconductor switch 23 of the voltage generator 20.

Accordingly, the trigger signal is supplied to each of the monostable circuits 41 and 42 at a period T1 proportional to the rotation period of the engine from the fluctuation of the voltage generated in the primary coil 22. Pulse signals of durations W1 and W2 are output from output terminals P2 and P4 from the monostable circuits 41 and 42, respectively. Since the capacity of the monostable circuit 41 is set to a value larger than the capacity of the monostable circuit 42, the duration W1 is longer than the duration W2. Therefore, in the comparison circuit 43 to which these pulse signals are input, a low-level signal is always output from the output terminal P5 based on the above logic table.

Next, it is assumed that the engine speed increases at time t11 and a trigger signal is supplied to each of the monostable circuits 41 and 42 at a period T2. This cycle T2 is shorter than the cycle T1 because the engine speed is increasing.
Therefore, the time for charging the capacitances of the monostable circuits 41 and 42 is reduced. For this reason, in the monostable circuit 41 having a large capacity, charging becomes insufficient, and the duration W1 of the output pulse signal becomes short. In this case, the durations from the monostable circuits 41 and 42 are substantially the same. The pulse signal is supplied to the comparison circuit 43. Therefore, the comparison circuit 4
3 continuously outputs a low-level signal.

Further, from time t21, the engine speed is increased and the trigger signal is changed to a shorter period T3.
Is supplied to each monostable circuit 41,. In this case, the charging of the monostable circuit 41 having a large capacity becomes further incomplete, and the duration W1 of the output pulse signal becomes shorter than the duration W2 of the pulse signal supplied from the monostable circuit 42. Therefore, based on the above logic table, a high-level signal is output from the comparison circuit 43 to which these pulse signals are input from the time t22 after the time W1 of the time t21 to the time t23 when the duration W2 ends. Is done. In the control unit 30 to which the signal from the comparison circuit 43 is input, it is possible to delay the ignition timing based on this high-level signal, and to suppress an increase in the engine speed.

FIG. 4 shows a voltage waveform generated in the primary coil 22. FIG. 4A shows a waveform having a period T1 proportional to the number of revolutions of the engine. In this state, as described with reference to FIG.
Output a low-level signal from the
There is no change in the operation of 0. As shown in FIG. 4B, when the rotation speed of the engine increases and reaches the period T3, the duration of the pulse signal from the monostable circuits 41 and 42 is reversed, so that a high-level signal is output from the overspeed prevention unit. It is output from 40. Accordingly, the control unit 30 delays the timing of turning off the switching element 25,
As shown in FIG. 4C, it is possible to obtain a waveform in which the ignition timing is delayed by the time T10. As a result, it is possible to suppress an increase in the number of revolutions of the engine and escape from an overspeed state.

As described above, in the ignition device of the present embodiment,
Determine the engine speed using two monostable circuits,
A function to prevent over rotation is realized. As shown in FIG. 2, the monostable circuit used in the present apparatus is an extremely simple circuit but highly reliable.
Further, by selecting the capacity and the resistance, it is easy to adjust the number of revolutions to be determined. Also, in the overspeed prevention section of this example, since the number of revolutions can be detected by comparing the pulse signals output from the monostable circuit, it is possible to compare a signal having a large amount of distortion, which directly shows the rotation of the conventional engine. As compared with the case where a simple configuration is used, high reliability can be ensured. Therefore, by installing the overspeed prevention unit using the monostable circuit according to this example, it is inexpensive, highly reliable,
Furthermore, an ignition device having an overspeed prevention function can be realized without changing the size of the device itself.

Although this embodiment has been described based on the overspeed prevention function for detecting the upper limit of the engine speed, the logic of the comparison circuit is changed so that the device having the same circuit configuration can be used as the engine speed. Of course, it is also easy to detect the lower limit, and it is of course possible to determine whether or not a predetermined number of revolutions has been reached. The number of monostable circuits is not limited to two, and three or more monostable circuits having different time constants are used.
It is also possible to detect two or more rotation speeds. In addition, 3
It is also possible to adopt a logic for improving reliability such as 2 out of 3 using the above monostable circuit.

[0024]

As described above, the rotation according to the present invention is performed.
In several detection device, first and second periodic pulse width
By the conversion means, the leading period of the trigger signal is expressed by binary logic.
Time compression in subsequent cycles as first and second pulse widths of
Because it can be converted, especially in observation or measurement
It can ensure the isomorphism of the transformation on the time axis
Logic operation, and relative binary logic operation between both pulse widths
Settings are delicate and unreliable
There is no need to introduce a reference value, and the number of revolutions
It is possible to accurately determine whether or not it has reached. In particular, power supply voltage changes
Fluctuation characteristics of both pulse widths due to movement and temperature changes are almost equal
Without considering the correlation with the change in the absolute reference value.
As a result, high temperature compensation performance and high reliability can be obtained.

[0025]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ignition device with an overspeed prevention function according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a monostable circuit used in the ignition device of FIG.

FIG. 3 is a timing chart showing an operation of an overspeed prevention section of the ignition device shown in FIG. 1;

FIG. 4 is an explanatory diagram showing operation waveforms of the ignition device shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Ignition device 11 ... Flywheel 12 ... Ignition plug 20 ... Voltage generating part 21 ... Ignition coil 22 ... Primary coil 23 ... Semiconductor switch 24 ... Base resistance 25 ... Switching element 26 ... Detection resistor 30 ... Control unit 40 ... Over-rotation prevention unit 41,42,45 ... Monostable circuit 43 ... Comparison circuit 46 ... Transistor switch 47 ..Capacity 48, 49 ... Resistance

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 45/00 362 F02P 1/08 F02P 1/08 301 F02P 5/155 F02D 41/22 330

Claims (3)

(57) [Claims] 1. A trigger signal according to a rotation speed of a rotating device.
Signal generating means for generating a first time constant element
And the trigger is triggered by the arrival of the trigger signal.
Within the subsequent period of the signal, the pulse width
First period / pulse width conversion for outputting first pulse signal
Means and a second time constant different from said first time constant element
Element, and triggered by the trigger signal
A pulse corresponding to the preceding cycle within the following cycle of the gar signal
Second period / pulse width for outputting second pulse signal of width
Conversion means, the first pulse signal and the second pulse
Performs a high-low logic operation on a signal and outputs a logic result.
Logic operation means for increasing or decreasing the rotation speed.
At least, the trailing edge of the pulse width of the first pulse signal is
2 so as to cross the pulse width trailing edge of the first pulse signal.
And a second time constant element is set . 2. The rotational speed detecting device as defined in claim 1.
An overspeed prevention device characterized by comprising: 3. A voltage generator for inducing a primary current of an ignition coil for supplying an ignition voltage for an ignition plug from a rotating operation of a rotor of a flywheel magneto, and a control unit capable of controlling the primary current. In the ignition device, generate a trigger signal according to the rotation speed of the rotating device
Having a trigger signal generating means and a first time constant element;
After the trigger signal arrives, it follows the trigger signal
The first pulse having a pulse width corresponding to the preceding cycle in the cycle
First period / pulse width conversion means for outputting a pulse signal;
It has a second time constant element different from the first time constant element.
When the trigger signal arrives, the trigger signal
Of the pulse width corresponding to the preceding cycle in the succeeding cycle of
Second period / pulse width conversion means for outputting a pulse signal of
Between the first pulse signal and the second pulse signal
A theory of executing a predetermined operation of high-low two logic and outputting a logic result
Operation means for increasing or decreasing the rotation speed.
The trailing edge of the pulse width of the first pulse signal is the second pulse.
The first and second signals so as to cross the trailing edge of the pulse width of the
Made by setting the constant element when said control unit, the logic
An ignition device comprising: an ignition timing control unit capable of adjusting a control timing of the primary current based on a result .