JP2641492B2 - Rotational angle position detection method for rotating body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting a rotational angle position of a rotating body such as a crankshaft of an internal combustion engine.

BACKGROUND ART An apparatus for determining a rotation reference position of a rotating body is disclosed in, for example, US Pat. No. 4,553,426.
In the apparatus described in the specification, a detector such as a magnetic projection is provided at equal angular intervals except for some missing portions in the rotation direction of the rotating body, and a predetermined level of output is provided each time the detector passes in the vicinity. The detection element that emits a signal is placed near the rotation locus of the detected element, the count value of the counter is incremented for each output generated by the detection element, and the counter value is reset when the detection element detects a missing part of the detected element. In other words, it is possible to determine whether or not the count value of the counter is a count value to be dealt with when the detecting element detects the missing part of the detected element, so that an accurate rotation reference position of the rotating body can be grasped. It is configured.

However, in the above apparatus, when the rotating body is rotated from a stationary state, and when the missing portion of the detected element is rotated from the stationary state immediately after passing through the vicinity of the sensing element, the rotating body is rotated. The rotation reference position cannot be obtained unless the rotating body makes two rotations.

SUMMARY OF THE INVENTION Accordingly, in view of the above-described circumstances, the present invention provides a method of detecting a rotation angle position of a rotating body, which requires a small amount of rotation of the rotating body from when the rotating body starts rotating until its reference rotation angle position is detected. It is intended to provide a way.

In order to achieve the above object, the present invention provides a rotating body which rotates together with a crankshaft of an engine, wherein one of a plurality of detected parts in an angular direction between adjacent detected parts in a rotational direction is maximum or minimum. A detection element that generates a pulse each time the detected part passes near the rotation locus of the detected part, and measures the generation interval of the pulse by time-measuring means. Calculating the ratio between the previous value and the current value, obtaining the maximum value or the minimum value of the ratio obtained for each rotation of the rotating body, detecting the reference rotation angle position of the crankshaft accordingly, A crank angle position detection method for detecting a crank angle position of the engine based on the detected reference rotation angle position, wherein when the rotation speed of the rotating body falls below a predetermined low rotation speed, the reference rotation angle Detecting the rotation angle position of the rotating body, wherein once the information on the degree position and the crank angle position is erased, the detection of the reference rotation angle position and the crank angle position is restarted after waiting for the next detection of the pulse. Provide a way.

Further, when the rotation speed of the rotating body drops below the predetermined low rotation speed, it is preferable to restart the reference rotation angle position detection.

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

FIG. 1 shows an ignition device for an internal combustion engine to which a method for detecting a rotational angle position of a rotating body according to the present invention is applied.

As shown in FIG. 1, in the present embodiment, a circular rotating body 2 is attached to a crankshaft 1 of an internal combustion engine (not shown), and the rotating body 2 is moved together with the crankshaft 1 in a clockwise direction in the figure. To rotate. On the outer peripheral portion of the rotating body 2, seven magnetic projections 3a, 3b,..., 3f, 3g are formed as detected parts so that the angular interval between the magnetic projections 3g, 3a in the rotation direction is maximized. In the vicinity of the rotation locus of the magnetic projection 3, a detection element 5 that generates a pulse every time the magnetic projection 3 passes near the magnetic projection 3 is provided. The detection element 5 is, for example, a magnetic sensor having a built-in magnetic coil, and is arranged so that the piston of the first cylinder of the engine is located at the top dead center when the magnetic projection 3a is detected.

Pulses generated by the detection element 5 detecting the magnetic protrusions 3a to 3g are input to the CPU 7 of the microcomputer M via the amplifier 6 which also functions as a waveform shaper. Accordingly, in the apparatus of this embodiment, during operation of the internal combustion engine, a pulse signal shown in FIG. 2 is input to the CPU 7 from the detection element 5 via the amplifier 6 in accordance with the rotation of the rotating body 2.

The microcomputer M described above has a CPU 7, a ROM 8, and a RAM.
10, a clock generator, etc., which detects the rotation angle position of the rotating body 2, that is, the reference rotation angle position of the crankshaft 1 according to a program described later based on the pulse, and the crankshaft 1 When the position is reached, a command signal is output to the ignition unit 12 via the amplifier 11.

The clock generator outputs the output of the oscillator 13 that generates a clock signal every predetermined period directly to the AND circuit 15 and to the AND circuit 17 via the frequency divider 16, while the AND circuit 17 A command signal from the CPU 7 is directly input, and a command signal from the CPU 7 is input to the AND circuit 15 via the inverter 18.
Thus, a clock signal relay-outputted is input to the CPU 7 via the OR circuit 20.

By configuring the clock generator in this manner, the period (frequency) of the clock signal input from the clock generator to the CPU 7 based on the command signal from the CPU 7
Can be changed, thereby making it possible to change the minimum operating voltage of the microcomputer M. That is, the CPU 7 and the battery (not shown)
Monitor the terminal voltage, engine speed (hereinafter, referred to as engine speed) or starter switch, etc.
By causing the command signal to be output when the battery voltage decreases during engine cranking or the like, and by increasing the cycle at which the clock signal is input to the CPU 7 (by decreasing the frequency), the minimum operating voltage of the microcomputer M is reduced. The microcomputer M can operate reliably even when the battery terminal voltage drops, such as during cranking.

FIG. 3 is a flowchart showing a part of a program for controlling the operation of the CPU 7. This program is executed every time the above-described pulse is generated, for example, by interrupting a main routine programmed for controlling the air-fuel ratio of the air-fuel mixture supplied to the engine.

First, when the microcomputer is powered on,
Initialization is performed simultaneously with power-on, and the count value and each flag of each counter described later are reset. Next, each step of the above-mentioned main routine is executed in synchronization with the above-mentioned clock signal. When a pulse (see FIG. 2) is input to the CPU during execution of the main routine, the CPU interrupts the main routine and executes the interrupt subroutine shown in FIG. 3 each time.

When the main routine is interrupted, first, it is determined whether or not the stage count value SC of the stage counter, which is incremented each time the interrupt subroutine is executed, is equal to the number of magnetic projections 3 (K = 7 in this embodiment). Determine (Step
S ₁ ), if they are equal, the stage count value SC
Is reset to 1 (step S ₂ ). Furthermore, it increments the stage count value SC when not equal (Step S _3).

Here, the role of the stage count value SC will be described. First, in this embodiment, as shown in FIG. 1, one rotation of the crankshaft 1 is composed of seven stages divided by magnetic projections 3a to 3g. Starting from the stage starting from the top dead center of the first cylinder corresponding to the reference rotation angle position, the stage numbers from 1 to 7 correspond to the respective magnetic projections on the front side in the rotation direction among the first magnetic projections sandwiching each stage. It is attached. Therefore, by matching the count value SC of the stage counter updated each time a pulse is generated with the actual stage number corresponding to the magnetic protrusion 3 detected by the detection element 5 as described later, the current stage count value SC is calculated from the stage count value SC. It is possible to know which stage the rotation angle position of the crankshaft 1 belongs to.

Returning to the explanation of the flowchart shown in FIG. 3, after execution of step S ₁ to S _3, whether or not the count value n of the pulse counter for counting the number of output times of pulses remains initialized immediately after power-on That is, it is determined whether or not n = 0 (step S ₄ ). If the count value n is 0, it means that the interrupt subroutine is executed first after the power is turned on. In this case, a timer necessary for measuring a pulse generation interval later is started ( step S _5), sets 1 in the flag Fa indicating that the reference rotational angle position of the crankshaft 1 is not detected yet (step S _6). The flag Fa is a flag that is reset to zero when the reference rotation angle position is detected. Then, the count value n of the pulse counter is set to 1 (step S _7),
Returning to the execution of the main routine, the generation of the next pulse interrupts the main routine again to execute the interrupt subroutine.

When the interrupt subroutine is executed again, steps S ₁ to S ₁
After the S ₃ has been performed, the determination in step S ₄ is performed. Here, since the count value n of the pulse counter is set to n = 1 by the execution of step S _7, the process proceeds to step S _8,
Whether the flag Fa is set to 1 or not, in other words,
Already reference rotational angular position is determined whether it is detected (Step S _8). Here, when the reference rotation angle position of the crankshaft 1 is detected by executing the later-described steps, the stage count value SC will be described later.
And the actual stage number corresponding to the magnetic projection 3 detected by the detection element 5 are matched, so that whether the rotation angle position of the crankshaft 1 belongs to the trigger stage to trigger the ignition unit 12 or not is determined. The determination is performed by determining whether or not the stage count value SC has a count value SCI that matches the stage number of the trigger stage (step S ₉ ), and when the stage count value SC matches the SCI. Ignites by issuing an ignition command signal to the ignition unit 12 (step
S _10), the process proceeds to step S _11. Note that the trigger stage is complicated depending on the number of cylinders of the engine. In this case, the count value SC corresponding to the stage number of the trigger stage is used.
I is also plural, and the ignition unit corresponding to each cylinder is triggered for each trigger stage. If 1 in the flag Fa in the step S ₈ is set, i.e., the actual stage numbers corresponding to the reference rotational angular position is magnetic projections 3 which is sensing element 5 with the stage count value SC not been detected yet detected If but have not been allowed to match, or stage count value SC in step S ₉
There is the case where it is determined that the rotational angle position of the crank shaft 1 does not match the SCI does not belong to a trigger stage that should trigger the ignition unit 12 proceeds to step S ₁₁ without emitting a ignition command signal.

Step S capturing _11, the timer value t _n indicated driven timer in step S ₅ in correspondence with the count value n of the pulse counter. Next, the count value n of the pulse counter
There it is determined whether or not the 1 (step S _12). Because if the execution of the interrupt subroutine after power-on is the second count value n is kept set to 1 at step S _7, whether 1 the flag Fa proceeds to step S ₁₃ is set Determine. Here, still flag Fa proceeds to step S ₁₄ because it is not reset to zero, whether or not the count value n K + 2 of the pulse counter (K is 7 in this embodiment the number of magnetic projections 3) coincides with the Determine.

Here, since the current count value n is 1, the count value n of the pulse counter is incremented (step
S _15), returns to the execution of the main routine.

When the interrupt subroutine is executed interrupting again the main routine at the next pulse generation, step S ₁
To S ₁₁ is performed in accordance with the procedure described above, the determination of step S ₁₂ is performed. Now since the count value n has a 2 is incremented in step S ₁₅ proceeds to step S _16, 1 in the flag Fa is determined whether it is set.
However, while the flag Fa is 1 set in step S _6, because it is not yet zero reset step
Advances to S _17, step S of the previous from the current timer value t _n of the taken at ₁₁ the timer value t generated interval _n-1 and subtracts pulses Delta] t _n
And stores it in association with the count value n. Then, 1 is determined whether it is set in the flag Fb (step S _18). The flag Fb is a flag that is set to 1 when the engine speed Ne exceeds a predetermined high-speed speed, for example, 3000 rpm. Since 1 is not set in the flag Fb immediately after the power is turned on, the process proceeds to step S Proceeding to ₁₉ , it is determined whether 1 is set in the flag Fa. Here, since the flag Fa remains set to 1, the count value n of the pulse counter is set to 2
Equal determines whether or not (step S _20). Since the current count value is 2 as described above, step S ₁₄
After a 3 increments the count value n proceeds to step S ₁₅ via returns to the execution of the main routine.

When the interrupt subroutine interrupt the main routine at the next pulse generation is performed, the process proceeds to step S ₁₉ as with the last execution of the interrupt subroutine, at this time n = 3 is determined in step S ₂₀ There, the current value Delta] t _n and the previous value Delta] t _n-1 of the count value n = pulse generation interval determined in step S ₁₇ proceeds to step S ₂₁ is not a 2
Determine the specific T _n of which is stored in correspondence with the count value n of the pulse counter (in the case of n = 3 is T ₃ = Δt ₃ / Δ
t _2). Then, performed is determined whether or not 1 in the flag Fa is set (step S _22). Since the flag Fa is remains still 1 is set proceeds to steps S ₁₄ → S _15,
The count value n of the pulse counter interrupt subroutine as in the case of the count value n is 3 until is performed (K + 2 = 9 in this embodiment) K + 2 in step S _14,
7 the ratio _{T n (T 3, T 4} , T 5, T 6, T 7, T 8, T 9) stores. When seven ratio T _n is stored, the count value n of the pulse counter at that time proceeds from step S ₁₄ since matching K + 2 in step S _23, 1 in the flag Fc is determined whether it is set. The flag Fc indicates that the engine speed Ne is within a predetermined speed range after the flag Fa is reset to zero (for example, 150 r
pm <Ne <a flag 1 is set when entering the 2000 rpm), since 1 flag Fc far not set, seven ratios stored in step S ₂₂ proceeds to step S ₂₄ The maximum ratio Tx is searched from T _n-6 , T _n-5 , T _n-4 ... T _n , and the count value x of the pulse counter when the maximum ratio Tx is obtained is obtained. stores the value x in the register a (step S _25). For example, the second
Assuming that the power is turned on and the engine is started at time ◎ in the figure, the pulse generation interval t _n is obtained from when the count value n of the pulse counter becomes 2, and the count value n
Is 3, the ratio T _n (= Δt _n / Δt _n-1 ) is obtained. Thus, not only is to wait until the count value n is K + 2 is at the start to get the amount of information required for detecting the reference rotational angle position of the crankshaft 1 (T number of _n), therefore step count value n in S ₁₄
Is determined to be equal to K + 2. Meanwhile, as shown in FIG. 2, when the engine is started, seven ratios stored in step S ₂₂ (T
₃ , T _4, ..., T ₈ , T ₉ ), the largest is T ₄ as shown in FIG. 2, and the count value n at that time is 4. Therefore, the count value 4 is stored in the register a.

The flowchart will be described again.
After execution of S _25, the current count value n and the register stored count value a (4) because the reference rotational angle position of the crank shaft 1 back number count value n from the count value n of the current pulse counter At this point, it can be seen whether the maximum ratio Tx corresponding to the reference rotation angle position of the crankshaft 1 has been obtained. Therefore, if the stage count value SC at that time is set to 1, the current stage count value SC
By replacing the value that can be taken by the SC with the current stage count value SC, the stage number and the stage count value SC can be matched. To carry out this operation is a step S _26. That is, in step S ₂₆ the count value n of the current pulse counter
From (n = 9) and the count value of the pulse counter when the maximum ratio T _n stored in the register a is obtained, n + 1−
If the stage count value SC when the stage number is 1 is set to 1 by performing the operation a, the value to be taken by the current stage count value SC is calculated and this value is set as it is as the stage count value SC. is there.
Explaining with the specific example shown in FIG. 2, the count value n of the pulse counter becomes 9, and the information required for the reference rotation angle position detection is complete, and the seven ratios (T ₃ , T _4, ..., T ₉₎ ) Is searched for the maximum ratio T ₄ (step S ₂₄ ), and the maximum ratio T 4
₄ is a pulse counter count value 4 when the obtained obtained (step _{S 25), n + 1-} a made of the current pulse count value of a counter n (n = 9) and register a to store the value 4 which In order to match the stage count value SC with the stage number by calculation, a value 6 to be taken by the current stage count value SC is obtained. This value is set to the current stage count value SC, and the stage number and the stage count value are set. Are matched (step
S _26).

Next, the latest pulse generation interval Δt _n is replaced with Δt _O and the latest timer value t _n is replaced with t _O (step
S _27). This is because the count value n of the pulse counter in the next step S ₂₈ is reset to 1, in steps S ₂₁ and S ₁₇ by the count value n = 1 when the interrupt subroutine is executed by the next pulse generator Δt _{O for} calculation
And t _O are required. In this manner, when the reference rotation angle position of the crankshaft 1 is obtained and the stage number and the stage count value SC are matched,
Flag Fa is reset to zero, is reset to 1 count n (step S _28).

Then, the interrupt subroutine is executed by the next pulse occurs after the execution as described above from step S ₁ to step S _11, the count value n is judged whether equal to 1 in step S _12. Here the count value n is because it is reset to 1 in step S ₂₈ proceeds to step S _13, 1 is judged whether it is set in the flag Fa. Since the flag Fa is reset to zero in step S _28, the process proceeds to step S _29, the engine speed Ne, the sensing element 5 fails to detect the detected portion 3 generates a predetermined level of the pulse Eze called It is determined whether or not the rotation speed is smaller than a predetermined low rotation speed, for example, 150 rpm at which pulse omission may occur. The engine rotational speed Ne, can be obtained by dividing by the corresponding angular interval of the magnetic projections 3 Delta] t _n in generation interval of the pulse obtained in step S _17. Step S ₂₉
In the case where Ne is equal to or greater than 150 rpm, Ne further exceeds a predetermined high rotational speed, for example, 3000 rpm, at which the rotation of the crankshaft 1 is stabilized and its rotation speed fluctuation is small, and the pulse generation interval Δt _n is small. dolphin whether determined (step S _30). Here, when Ne is 3000 rpm or less, Ne further determines whether or not Ne is within a predetermined rotation speed region (for example, 150 rpm ≦ Ne <2000 rpm) where the rotation speed fluctuation of the crankshaft 1 is large. determining by determining whether the below (step S _31). Where N
When e is 2000 rpm or more, that is, 2000 rpm ≦ Ne
If was ≦ 3000 rpm, after seeking the generation interval Delta] t _n pulse proceeds to step S _17, the flag Fb and Fa are both 1 proceeds to steps S ₁₈ → S ₁₉ → S ₂₁ because it is not set ratio seeking T _n, the count value n proceeds from step S ₂₂ to step S ₃₂ it is determined whether or not equal to K (K = 7). If the count value n is not equal to K, step S
Proceed to ₁₅ to increment the count value n.

The next pulse occurs, the interrupt subroutine is executed, after being executed as described above to step S ₁ to S _11,
Determination of step S ₁₂ is performed. Here, the count value n is incremented in step S _15, since a 2, the process proceeds to step S _16, 1 is judged whether it is set in the flag Fa. Since the flag Fa has already been reset to zero as described above, step S ₃₃
Then, it is determined whether or not 1 is set in the flag Fb. Since the flag Fb 1 has not yet been set, 1 in the flag Fc advances to step S ₃₄ it is determined whether it is set. Here, 1 has not yet been set in the flag Fc. Thus, after obtaining the occurrence interval Delta] t _n of the pulse at step S _17, the process proceeds to steps S ₂₂ → S ₃₂ → S ₁₅ seek proceeds ratio T _n in step S ₁₈ → S ₁₉ → _21. After crankshaft 1 performs this operation until the count value n is equal to K was determined the ratio T _n of the predetermined number which is obtained per rotation (7), the following steps: Step S ₂₃ from step S ₃₂ If there is a difference between the actual stage number and the stage count value SC, correct it.

After the flag Fa is the count value n is reset to 1 with reset to zero, when the engine speed Ne falls below the 2000rpm in step S _31, namely, 150 rpm
When a ≦ Ne <2000 rpm is set to 1 in the flag Fc (step S _33), it decides whether or not the count value n is equal to K (K = 7) (step S _35), n = K increments the proceeds count value n in step S ₁₅ through step S ₃₂ if not.

After being executed when the interrupt subroutine is executed from Step S ₁ to S ₁₁ by the next pulse occurs, the count value n
Since it has become incremented n> 1 in step S _15, the flag Fc advances to steps S ₁₆ → S ₃₃ → S ₃₄
Since 1 is set in step S ₃₃ to proceed to step S _35. This operation is repeated until the count value n is n = K, the n = K when seeking generation interval Delta] t _n of the pulse at that time (step S _36), the process proceeds to step S ₂₃ through step S _32. Here, the flag Fc is set in step _S33.
Since one is left has been set in, step S ₂₄ ~S
Without detection of the reference rotational angle position at _26, the step S ₂₇ to perform the following steps, in step S _28,
The flag Fc is reset to zero and the count value n is reset to one.

That is, the engine speed Ne is within a predetermined speed range (150r
pm ≦ Ne <2000 rpm), steps S ₂₄ and S _24
25, with each other to a to cancel the detection of the reference rotational angular position rambling execution of S _26. The reason for this is that the magnetic projection corresponding to the stage number 1 corresponds to the stage number 1 because the rotation speed of the crankshaft 1 is large due to the initial explosion immediately after the start of the engine and the rotation speed is large due to the engine blowing. There ratio T _n obtained in step S ₂₁ at the time of pulse generation may become smaller than the other ratios T _n obtained during one crankshaft rotation according 3a, whereby already the stage count value is made to coincide with the stage number This is to prevent the SC from being disturbed. Note that this predetermined rotation speed region (150 rpm ≦ Ne
<2000rpm), since Ne is higher than the rotation speed (150rpm) at which the so-called pulse omission occurs,
Already updated the stage count value SC which is allowed consistent with stage numbers for each pulse generator (step S ₁ ~S _3),
By monitoring the stage count value SC, the current rotational angle position of the crankshaft 1 can be known.

After the flag Fa is reset to zero and the count value n is reset to 1, an interrupt subroutine is executed,
When the engine speed Ne exceeds the 3000rpm in step S ₃₀ is set to 1 in the flag Fb (step S
₃₇ ). Then, determine the pulse generation interval Δt _n (step
S _17), it decides whether or not 1 in the flag Fb is set (step S _18), the ratio proceeds to step S ₃₈ (Δt _n / Δt
it is stored as T _n a Delta] t _n instead of _n-1) (step S _38). Then increments the count value n proceeds to steps S ₃₂ → S _15.

When the interrupt subroutine is executed by the next pulse occurs after the execution of Step S ₁ to S _11, step S ₁₂
Through the discriminating step S _16, S _33. Since 1 flag Fb is set, obtains the generation interval Delta] t _n pulse proceeds to step S _17, step S ₁₈ → S ₃₈ → S ₃₂
And proceed. This operation is repeated until the count value n is n = K, step through step S ₂₃ when it comes to n = K S
₂₄ → S ₂₅ → S _26, and instead of the ratio (Δt _n / Δt _n-1 ), T _n
The maximum value of Δt _n stored as is searched, and based on this, the reference rotation angle position is detected retrospectively, and if the actual stage number is different from the stage count value, this is corrected.

That is, when the engine speed Ne is a predetermined high speed (for example,
3000rpm), the crankshaft 1
The maximum Δt _n is determined from a predetermined number (7) of pulse generation intervals Δt _n obtained each time the motor rotates, and the reference rotation angle position of the crankshaft 1 is determined retrospectively in accordance with the maximum Δt _n. This is to match the count value SC. As described above, the pulse generation interval Δt _n is used instead of the ratio (Δt _n / Δt _n-1 ) because the engine rotation speed Ne exceeds the predetermined high rotation speed (3000 rpm). The rotation speed fluctuation of the shaft 1 becomes small,
Pulse interval Δt without using ratio (Δt _n / Δt _n-1 )
The required calculation processing time of the microcomputer can be shortened by eliminating the division step (S ₂₁ ) that can accurately detect the reference rotation angle position from _n and the calculation processing time is long, and the engine rotation speed Ne is increased. In this case, the calculation speed of the microcomputer can sufficiently follow this.

Further, in step S _29, the engine speed Ne is 150
When the rotation speed falls below rpm, the count value n is reset to zero and the system itself is reset, and the operation returns to the operation for obtaining the reference rotation angle position again, as in the beginning of engine start when the reference rotation angle position is not obtained. The rotation angle position is detected. This is because, when the engine speed Ne falls below a predetermined low speed (for example, 150 rpm), the detection element 5 fails to detect the detected part 3 and cannot generate a pulse of a predetermined level or more. Since so-called pulse omission occurs, it is conceivable that the stage number and the stage counter value SC do not coincide with each other. Therefore, the reference rotation angle position of the crankshaft 1 is completely newly detected.

Effect of the Invention As described above, in the crank angle position detecting method according to the present invention, a plurality of detected parts are arranged on a rotating body that rotates together with the crankshaft of the engine in the rotation direction, and the angular interval between the detected parts adjacent to each other. Is formed so that one of them becomes maximum or minimum, and a detection element is provided near the rotation locus of the detected part to generate a pulse each time the detected part passes through the vicinity. And the ratio between the previous value and the current value of the occurrence interval is calculated, and the maximum value or the minimum blood in the ratio obtained for each rotation of the rotating body is obtained, and the reference of the crankshaft is accordingly determined. A rotational angle position is detected, and a crank angle position of the engine is detected based on the detected reference rotational angle position. Further, the rotational speed of the rotating body falls below a predetermined low rotational speed. In this case, after the information regarding the reference rotation angle position and the crank angle position is once deleted, the detection of the reference rotation angle position and the crank angle position is restarted after waiting for the next detection of the pulse. Therefore, it is possible to prevent the rotation angle position from being erroneously detected due to the failure of the detection of the detected portion of the detection element which is likely to occur below the predetermined low rotation speed, and to newly detect the reference rotation angle position promptly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an ignition device of an internal combustion engine to which the present invention is applied, and FIG. 2 is a diagram showing signal waveforms of pulses input to a CPU shown in FIG. 1, a stage number corresponding to each pulse, and pulse numbers. count value n, the stage count value SC, the pulse generation interval Delta] t _n, the diagram showing the ratio T _n of the generation interval Delta] t _n, FIG. 3 is a flowchart showing the operation of the CPU shown in Figure 1. Description of Signs of Main Parts 1 ... Crankshaft 2 ... Rotating Body 3a to 3g ... Magnetic Projection 5 ... Detection Element 7 ... CPU 12 ... Ignition Unit M ... Microcomputer

Claims (1)

(57) [Claims] A rotating body that rotates together with a crankshaft of an engine, wherein a plurality of detected parts are formed in a direction of rotation such that one of angular intervals between adjacent detected parts is maximum or minimum; A detection element that generates a pulse every time the detected portion passes in the vicinity of the rotation locus of the detected portion is provided, and the pulse generation interval is measured by a timer.
The ratio between the previous value and the current value of the generation interval is calculated, and the maximum value or the minimum value of the ratio obtained for each rotation of the rotating body is determined, and the reference rotation angle position of the crankshaft is accordingly determined. A crank angle position detection method for detecting and detecting a crank angle position of the engine based on the detected reference rotation angle position, wherein when the rotation speed of the rotating body falls below a predetermined low rotation speed, A method of temporarily erasing information relating to a reference rotation angle position and the crank angle position and then restarting detection of the reference rotation angle position and the crank angle position after waiting for the next detection of the pulse; Position detection method.