JP2693966B2 - Crank position detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crank position detecting device that detects a crank position, which is input information necessary for engine ignition timing control or fuel injection control, and outputs a signal. .

[Problems to be Solved by the Related Art and Invention] Conventionally, as a crank position detecting device for an automobile engine, a device in which a disc-shaped rotor is provided with a protrusion to detect the crank position is known. The protrusions are arranged on the circumference of the rotor at equal or unequal pitch intervals.

A rotor having protrusions of unequal pitch is disclosed, for example, in Japanese Patent Application Laid-Open No. 61-23875 as an ignition device for an automobile engine.

FIG. 7 shows a conventional example of a rotor having such unequal pitch protrusions. FIG. 7 is a configuration diagram of an ignition timing control device using a crank position detection device. In the conventional rotor 101, all the protrusions on the circumference have substantially the same height.
This protrusion is an electromagnetic pickup that is an example of a magnetic sensor.
It is detected by 102 and input to the control circuit 103. The above control circuit
At 103, an output from the electromagnetic pickup 102 is converted into a crank pulse by a waveform shaping circuit, and a signal from a load sensor 104 such as a suction pipe pressure sensor is further taken in. Based on the crank pulse, an ignition timing and an engine speed are obtained. Is calculated and the ignition timing is controlled.

Here, the output voltage of the electromagnetic pickup 102 is generated by the change of the magnetic flux φ when the projection of the rotor 101 passes through the electromagnetic pickup 102 through a predetermined clearance due to the rotation of the rotor 101, and this magnetic flux change. dφ / d
A voltage (AC voltage) e proportional to t is output from the electromagnetic pickup. The output of the electromagnetic pickup is the sixth
A signal waveform as shown by F in the figure is obtained, and this signal F is input to the waveform shaping circuit, and the slice level signal G for determining the voltage level for converting the AC output of the electromagnetic pickup 102 into a pulse is compared with the signal F. , Crank pulse H is waveform-shaped and output.

Normally, in order to prevent an output error of the crank pulse due to the output variation of each electromagnetic pickup 102 with respect to the output of such an electromagnetic pickup 102, the slice level is not fixed and is changed according to the input to the waveform shaping circuit. It has become. However, this slice level depends on, for example, the charging and discharging voltages of the capacitor 32 of the waveform shaping circuit as shown in FIG. 3, and the slice level becomes unnecessarily high in the portion where the protrusion interval of the rotor 101 is narrow. On the contrary, in a portion where the protrusion interval is wide, the slice level is lowered due to the discharge of the capacitor 32.

Further, when the height of the protrusions is small and the protrusion height on the rear side in the rotation direction of the portion having a small protrusion interval is low and the clearance with the electromagnetic pickup 102 is large, the change in the magnetic flux passing through this clearance becomes small, Therefore, as described above, the output from the electromagnetic pickup 102 decreases. Therefore, the slice level becomes lower than the above-mentioned unnecessarily high slice level, and a crank pulse output error occurs, as shown in FIG. When this output error occurs, the capacitor 32 is not charged, and the slice level is remarkably reduced in the portion where the protrusion interval up to the next protrusion is wide, and noise is mixed in the electromagnetic pickup system. As shown, noise is output as a crank pulse.

Therefore, due to the output error of the crank pulse and the generation of an abnormal pulse due to the mixing of noise, the proper crank angle or engine speed cannot be calculated, and the ignition system or the fuel injection system malfunctions, resulting in engine output. There is a problem in that it causes a decrease in fuel consumption, a reduction in exhaust gas purification rate, and a deterioration in fuel consumption rate.

[Object of the Invention] The present invention has been made in view of the above circumstances, and despite the output variation of the magnetic sensor due to the rotor,
An object of the present invention is to provide a crank position detecting device capable of always detecting an accurate crank position and preventing malfunction in ignition timing control or fuel injection control.

[Means and Actions for Solving the Problems] A crank position detecting device for an engine according to the present invention includes a crank position detecting unit including a pair of a pulse detecting member on the advance side and a pulse detecting member on the retard side as the pulse. According to the signal waveform from the pulse detection member and the signal waveform from the rotor, a plurality of pairs of rotors are arranged at an interval larger than the interval of the detection member, a magnetic sensor provided facing the pulse detection member via a predetermined clearance. A waveform shaping circuit for comparing set slice levels and outputting a crank pulse is provided, and the advance side pulse detection member is provided with a slobe in which the clearance gradually changes.

That is, in the crank position detecting means according to the present invention, the outputs corresponding to the advance side pulse detection member and the delay side pulse detection member detected by the magnetic sensor are the advance side outputs generated earlier. The output is relatively smaller than the output on the retard side that occurs later, and this is the output sequence that is continuously repeated. The waveform shaping circuit compares the signal waveform from the pulse detection member detected by the magnetic sensor with the slice level set by the signal waveform and outputs a crank pulse.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 4 show a first embodiment of the present invention, FIG. 1 is a configuration diagram in which the crank position detecting device according to the present invention is used for ignition timing control, and FIG. 2 is a functional block diagram of ignition timing control. 3, FIG. 3 is a circuit diagram of the waveform shaping circuit, and FIG. 4 is a time chart diagram of waveforms in the circuit of FIG.

(Structure) Reference numeral 1 in the drawing is a disk-shaped crank rotor made of a magnetic material that is axially attached to a crankshaft (not shown) of an engine, as an example of a rotor that rotates in association with engine rotation. Is an electromagnetic pickup which is an example of a magnetic sensor provided opposite to the crank rotor.

In the crank rotor 1, as shown in FIG. 1, the crank position detecting portion 1a has an advance side protrusion E and a retard side protrusion D, which are examples of pulse detecting members, at a predetermined angle θ. It is integrally provided on the circumference of 1. Further, the crank position detectors 1a are provided at two target positions at intervals larger than the angle θ.

Here, the projection D on the retard angle side is formed in a rectangular shape, while the projection E on the advance angle side is formed on the side wall on the front side in the rotation direction with respect to the electromagnetic pickup 2 with respect to the rectangle, from the tip of the rectangle to the crank. The shape is such that a slobe whose height changes gently toward the outer circumference of the rotor 1.

Further, reference numeral 3 is a control means, which inputs the load sensor 9 such as a suction pipe pressure sensor and the output of the electromagnetic pickup 2.

Further, the control means 3 includes a central processing unit (CPU) 5, a ROM 6 and a RAM which are connected to each other via a bus line 4.
7, an input / output (I / O) interface 8 is provided.

The ROM 6 stores a control program and fixed data, and the RAM 7 stores temporary parameters after data processing of output signals of the electromagnetic pickup 2 and the load sensor 9.

The CPU 5 calculates the ignition time according to the program stored in the ROM 6, and the I / O interface 8
An ignition signal is output to the base of the power transistor 10 via.

The primary side of the ignition coil 11 is connected to the collector of the power transistor 10 via a power source BV, and the emitter of the power transistor 10 is grounded. On the other hand, the secondary side of the ignition coil 11 is connected to the distributor 12
Further, the distributor 12 is connected to a spark plug 13 provided in each cylinder of the engine.

With the above configuration, when the ignition signal from the control means 3 is input to the power transistor 10 and the primary current of the ignition coil 11 is turned on / off, a high voltage is generated on the secondary side of the ignition coil 11, and the high voltage is generated via the distributor 12. Ignition plug for a given cylinder
Spark 13 selectively.

(Functional Configuration of Electronic Control System) The control means 3 includes the waveform shaping circuit 14 and the load calculation means 1
5, switch means 16, engine speed calculation means 17, ignition angle search means 18, timer means 19, cycle calculation means 20, ignition time calculation means 21, and incorporates output signals from the electromagnetic pickup 2 and load sensor. It is arithmetically processed and output to the ignition means 22.

Here, the output signal from the electromagnetic pickup 2 is input to the waveform shaping circuit 14, converted into a crank pulse, and output to the switch means 16. The switch means 16 selectively switches between the signal from the projection E on the advance side and the signal from the projection D on the retard side of the crank position detector 1a, and the timer means 19, the engine speed calculation means 17, and the cycle calculation. Output to each means 20.

In the cycle calculating means 20, the difference between the time when the protrusion D on the retard side of the crank position detector 1a is detected and the time when the protrusion E on the advance side of the next crank position detector 1a is detected. Thus, the period, that is, the angular velocity information of the crankshaft is obtained. This angular velocity information is used by the engine speed calculation means 17
Is calculated as the engine speed.

On the other hand, the output signal from the load sensor 9 is input to the load calculation means 15, the engine load such as the suction pipe pressure is calculated, and input to the ignition angle search means 18.

The ignition angle search means 18 obtains a basic ignition angle by map search or the like using the engine load such as the suction pipe pressure calculated by the load calculation means 15 and the engine speed as parameters, and outputs it to the ignition time calculation means 21. To do.

The ignition time calculating means 21 detects the advance-side protrusion E indicating the reference position of the crank position detecting portion 1a from the input basic ignition angle and the crank angular velocity information from the cycle calculating means 20. The time, that is, the ignition time is obtained, and this is set in the timer means 19.

The timer means 19 starts timing with a signal when the protrusion E on the advance side is detected, and outputs an ignition signal to the ignition means 22 when the set ignition time is reached.

The ignition means 22 is composed of the power transistor 10, the ignition coil 11, the distributor 12, the ignition plug 13 and the like, and turns on and off the power transistor 10 by an ignition signal from the timer means 19, as described above. Then, spark the spark plug 13 of the corresponding cylinder.

Here, as shown in FIG. 3, in the waveform shaping circuit 14, the cathode of the diode 30 and the anode of the diode 31 and the inverting input terminal of the comparator 36 are connected as input terminals, and the diode 30 is further connected. The anode of is grounded. The cathode of the diode 31 is connected to one terminal of a capacitor 32, and the other terminal of the capacitor 32 is grounded. Furthermore, the above capacitors
The positive terminal of 32 is connected to the non-inverting input terminal of the comparator 36 via resistors 33 and 35, while the resistor 33
The connection end of the resistor 35 and the resistor 35 is grounded via the resistor 34.
The output terminal and the non-inverting input terminal of the comparator 36 are connected via the feedback resistor 37, and are configured as a Schmitt comparator having hysteresis.

With the above configuration, the output signal (AC voltage) of the electromagnetic pickup 2 is waveform-shaped and output as a crank pulse.

(Operation) Next, the operation of the embodiment having the above configuration will be described.

(Output from Electromagnetic Pickup) When the crank rotor 1 rotates due to the operation of the engine, the protrusion E on the advance angle side provided on the crank position detecting portion 1a.
And the projection D on the retard side interrupts the magnetic field generated in the head of the electromagnetic pickup 2 to generate a voltage (AC voltage). This voltage is output from the electromagnetic pickup 2,
It is input to the waveform shaping circuit 14 as a signal shown in A of FIG.

Here, the protrusion E on the advance side of the crank position detector 1a
Has a slope on the front side in the rotational direction with respect to the electromagnetic pickup 2, the slope of which gradually changes in height. Therefore, the head of the electromagnetic pickup 2 and the protrusion E on the advance side are provided.
The clearance formed by is gradually changed with the rotation of the crank rotor 1. Therefore, the protrusion E on the advance angle side
The change in the magnetic flux passing through the clearance in is smaller than the change in the magnetic flux passing through the clearance in the protrusion D on the retard angle side. Therefore, as described above, the voltage (AC voltage) generated in the electromagnetic pickup 2 is proportional to the change in the magnetic flux, so that the protrusion E on the advance side has the electromagnetic pickup 2 as shown in A of FIG. The voltage generated when passing through the electromagnetic pickup 2 is relatively smaller than the voltage generated when the protrusion D on the retard side passes through the electromagnetic pickup 2.

(Waveform shaping) The output signal of the electromagnetic pickup 2 is waveform shaped by the waveform shaping circuit 14 shown in FIG. 3 and output as a crank pulse. This operation will be described with reference to the time chart of FIG.

First, when the output voltage of the electromagnetic pickup 2 corresponding to the advance E on the crank position detector 1a is extremely small, the diode 31 does not conduct and the electric charge remaining in the capacitor 32 is discharged through the resistors 33 and 34. ing. At this time, the voltage input to the inverting input terminal of the comparator 36 is smaller than the voltage input to the non-inverting input terminal of the comparator 36 from the capacitor 32 via the resistors 33 and 35. Therefore, the output of the comparator 36 is at high level.

Next, the output voltage of the electromagnetic pickup 2 rises,
When the voltage at the inverting input terminal of the comparator 36 becomes higher than the voltage at the non-inverting input terminal, that is, the voltage on the cathode side of the diode 31, the output of the comparator 36 is inverted from a high level to a low level and the diode 31 becomes conductive. Then, the capacitor 32 starts to be charged.

Furthermore, the voltage input to the non-inverting input terminal of the comparator 36 continues to increase, and finally passes the peak and decreases, that is, the charging voltage of the capacitor 32, that is, the comparator.
When the voltage becomes lower than the voltage of the non-inverting input terminal of 36, the output of the comparator 36 is inverted from low level to high level again, and shaped as a crank pulse.

The comparator 36 has hysteresis due to the feedback resistor 37, and the output level of the electromagnetic pickup 2 is
Even if the output of the comparator 36 changes relatively gently in the vicinity of the inversion level of the comparator 36 and the output fluctuates or has a minute noise, the output of the comparator 36 is prevented from being turned on and off unnecessarily.

At this time, the charging of the capacitor 32 stops and the resistance
The discharge is started through 33 and 34. Further, when the output voltage of the electromagnetic pickup 2 drops, the load is cut off by the diode 30, and the output voltage of the electromagnetic pickup 2 is rectified. The voltage waveform at the non-inverting input terminal of the comparator 36 is shown as a slice level in B of FIG.

Here, as described above, the output voltage corresponding to the protrusion E on the advance side is smaller than that of the conventional one, so that the charge amount of the capacitor 32 is decreased, and the output voltage tends to be higher than necessary. The slice level is lowered.

Next, when the output voltage of the electromagnetic pickup 2 corresponding to the projection D on the retard side of the crank position detecting portion 1a is input, the same thing is repeated, but the projection E on the advance side as described above. Since the slice level in the section corresponding to the projection D on the retard side is relatively lower than that of the conventional one, the projection height of the projection D on the retard side is set to be higher than that on the advance side due to variations in production or the like. Even if the output voltage corresponding to the projection D on the retard side of the electromagnetic pickup, which is lower than the projection height of the projection E, is reduced, the crank pulse is reliably output without falling below the slice level.

That is, even if there are variations in the output peak value of the electromagnetic pickup 2 due to variations in the protrusion height of the crank rotor 1 and the like, it is possible to ensure that the output level is above the slice level, and a crank pulse output error causes a waveform shaping circuit.
14 can be prevented without modification.

Further, as a result, the slice level in the narrow section from the output voltage corresponding to the protrusion E on the advance side of the crank position detecting portion 1a to the output voltage corresponding to the protrusion D on the next retard side becomes larger than necessary in the past. The level is lowered from a high level, and the level is approximately the same as the slice level in a wide section up to the output voltage corresponding to the protrusion E on the next advance side, and the averaging is performed. Therefore,
There is no local reduction of the slice level in the portion where the output interval of the electromagnetic pickup 2 is wide due to uneven pitch protrusions, and even if noise is mixed in the electromagnetic pickup system, the slice level does not reach the slice level. circuit
Abnormal signal output from 14 is prevented.

Although the load sensor 9 is described as the intake pipe pressure sensor in this embodiment, a throttle position sensor, an air flow meter, or the like may be used to detect the engine load, and the fuel injection pulse may be used as the engine load parameter. The width may be used.

Further, the angle θ between the slob formed on the protrusion E on the advance side of the crank rotor 1 and the tangential direction of the crank rotor 1 is θ.
₀ is effective at ₀ to 60 °, and about 30 ° is desirable.

Second Embodiment Next, a second embodiment according to the present invention will be described. In the second embodiment, the same members as those in the first embodiment described above are designated by the same reference numerals, and the description and illustration thereof are omitted.

FIG. 5 shows the second embodiment of the present invention, and is a block diagram of a crank position detecting device, which is a disk-shaped crank rotor 50 made of a magnetic material and axially attached to an engine crankshaft (not shown). The electromagnetic pickup 2 is an example of a magnetic sensor.

In the crank rotor 50, as shown in FIG. 5, a notch E2 on the advance side and a notch D2 on the retard side, which are an example of a pulse detecting member, are notched at a predetermined angle θ in the crank position detecting section 50a. There is. Further, the crank position detectors 50a are provided at two positions at target positions at intervals larger than the angle θ.

Here, the notch D2 on the retard angle side is notched in a rectangular shape, while the notch E2 on the advance angle side is a rectangular notch on a side wall on the rear side in the rotation direction with respect to the electromagnetic pickup 2. It has a shape in which a slope-shaped notch that gently rises from the bottom of the notch toward the outer periphery of the crank rotor 50 is added.

Therefore, the clearance formed by the head of the electromagnetic pickup 2 and the notch E2 on the advance side gradually changes as the crank rotor 50 rotates. Therefore, the change in the magnetic flux passing through the clearance in the notch E2 on the advance side is smaller than the change in the magnetic flux passing through the clearance in the notch D2 on the retard side, and the same effect as in the first embodiment is obtained. The effect is obtained.

At this time, the output waveform of the electromagnetic pickup 2 is a waveform in which the positive and negative sides of the waveform A in FIG. 4 are reversed.

[Effects of the Invention] According to the present invention as described above, the output train from the magnetic sensor can be lowered relative to the output generated later in the portion having a narrow output interval. The unnecessarily high detection level in the portion where the output interval of the magnetic sensor output is narrow is lowered and averaged, and despite the output variation of the magnetic sensor due to the rotor, the configuration is simple and the cost is increased. It is possible to always detect an accurate crank position without any noise, and to improve noise resistance in a portion where the output interval of the magnetic sensor is wide. Therefore, the ignition timing control or the fuel injection control can always be performed accurately, the exhaust gas purification rate is improved, and the fuel consumption rate is significantly improved, which is an excellent effect.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a configuration diagram in which the crank position detecting device according to the present invention is used for ignition timing control, and FIG. 2 is a functional block diagram of ignition timing control. ,
FIG. 3 is a circuit diagram of a waveform shaping circuit, FIG. 4 is a time chart diagram of waveforms in the circuit of FIG. 3, FIG. 5 shows a second embodiment of the present invention, and a configuration diagram of a crank position detecting device. FIG. 6 and subsequent figures show a conventional example, FIG. 6 is a time chart of waveforms, and FIG. 7 is a configuration diagram of ignition timing control using a crank position detecting device. 1,50 ...... Rotor, 2 …… Magnetic sensor, 1a, 50a …… Crank position detection unit, E, E2 …… Advance side pulse detection member, D, D2
...... The pulse detection member on the retard side.

Claims (1)

(57) [Claims] 1. A rotor in which a plurality of crank position detection units each including a pulse detection member on the advance side and a pulse detection member on the retard side are arranged at a plurality of intervals larger than the intervals of the pulse detection members. A magnetic sensor provided facing the pulse detection member via a predetermined clearance, and a waveform shaping circuit for comparing a signal waveform from the pulse detection member with a slice level set by the signal waveform to output a crank pulse A crank position detecting device, comprising: a pulse detecting member on the advance side, which is provided with a slope in which the clearance gradually changes.