JPH0436043A - Detecting device for crank angle of engine - Google Patents

Abstract

PURPOSE:To obtain accurate data for controlling an engine according to output of one crank angle sensor even if the other crank angle sensor is out of order by correcting the deviation of time between the outputs of first and second crank angle sensors. CONSTITUTION:Under normal conditions, the crank angle of an engine is detected according to the output of a first crank angle sensor 20, and when the first crank angle sensor 20 is out of order the deviation of time between the outputs of first and second crank angle sensors 20, 28 is corrected. Thereafter, the output utilized is changed from first to second crank angle sensor 28 by a changing means 35.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crank angle detection device for an engine, and particularly to one in which crank angle sensors are provided on a crankshaft and a camshaft, respectively.

(Prior Art) In general, in automobile engines, the rotation angle of the crankshaft (hereinafter referred to as crank angle) is used to determine the engine rotation speed and rotation phase necessary to control fuel injection timing, ignition timing, etc. It is equipped with a crank angle sensor for detection (see Japanese Patent Laid-Open No. 1-219342).

This crank angle sensor is generally configured to indirectly determine the crank angle from the rotation angle of the camshaft or the rotation angle of the rotation shaft of a distributor that is connected to the camshaft and rotates. The disk plate includes a disk plate having a number of slits arranged radially at predetermined angular intervals and fixed to the rotating shaft of the distributor, and a Hall element and an electromagnet disposed facing each other with the disk plate in between. A Hall element detects the magnetic field passing through the slit and outputs a rectangular wave pulse signal.

By the way, when the camshafts provided on the left and right banks are interlocked and connected to the crankshaft via a timing belt, as in a V-6 engine, for example, the timing belt becomes longer as a whole, and the belt length increases. The amount of change in length due to the magnitude of tension increases, and a phase shift in the rotation angle of the camshaft relative to the crankshaft occurs. Therefore, it is desirable to directly detect the rotation angle of the crankshaft to prevent deviations in fuel injection timing and ignition timing, but since the crankshaft is usually installed at the bottom of the engine, When installing a rectangular wave output type crank angle sensor using a Hall element as described above, foreign matter such as dirt may adhere to the slit of the disc plate or the gap between the disc plate and the Hall element, making it relatively easy to use. It becomes impossible to reliably detect the crank angle within a short time.

Therefore, it is conceivable to provide a crank angle sensor consisting of an electromagnetic pickup type sensor on the crankshaft and its vicinity.

However, although electromagnetic pickup type sensors have the property of being difficult to fail due to the adhesion of foreign substances such as mud, the rate of change in magnetic flux is small in the low rotation range such as during the cranking period when starting the engine. There is a problem in that the crank angle signal cannot be detected effectively, and until the engine speed rises to a certain extent and the crank angle signal can be detected, the complete explosion timing is delayed and the starting time becomes long.

Therefore, when the engine speed is in a predetermined low speed range, engine control data is calculated based on the detection signal from the second crank angle sensor on the camshaft side, and when the engine speed is outside the predetermined low speed range, the crankshaft It has also been proposed to calculate engine control data based on a detection signal from a first crank angle sensor on the side.

However, in addition to the detection delay of the electromagnetic pickup type crank angle sensor that outputs a sine wave signal, there is a delay time required for waveform shaping processing to convert the sine wave signal into a rectangular wave signal. The delay time is longer than that of the crank angle sensor, and this delay time increases significantly as the engine speed increases.

Therefore, if the ignition timing and fuel injection timing set in consideration of the delay time described above for the electromagnetic pickup type first crank angle sensor are applied to the Hall element type second crank angle sensor, the timing of ignition and fuel injection will be advanced. This results in the problem that proper engine control cannot be performed.

(Object of the Invention) Therefore, an object of the present invention is to provide an engine crank angle detection device that can output a highly accurate crank angle signal over all engine operating ranges.

(Structure of the Invention) The engine crank angle detection device according to the present invention includes a first crank angle sensor that detects the rotation angle of the crankshaft, and a second crank angle sensor that detects the rotation angle of the camshaft. The apparatus further includes a correction means for correcting a temporal deviation between the outputs of the first and second crank angle sensors, and a switching means for switching the corrected output of the first or second crank angle sensor according to conditions. It is characterized by the presence of

Further, the engine crank angle detection device according to the present invention includes a first crank angle sensor that detects the rotation angle of the crankshaft, and a second crank angle sensor that detects the rotation angle of the camshaft. The engine crank angle is detected based on the output of the sensor, and when the first crank angle sensor fails, the output of the second crank angle sensor is corrected for the temporal deviation between the outputs of both crank angle sensors. It is equipped with a switching means for switching to.

Furthermore, the engine crank angle detection device according to the present invention includes:
The amount of correction for the temporal deviation between the outputs of the first and second crank angle sensors is increased as the engine speed increases.

(Effects of the Invention) According to the present invention, the first and second crank angle sensors are provided, and the correcting means for correcting the temporal deviation between the outputs of both crank angle sensors is provided. Even if one sensor fails, accurate data for engine control can be obtained based on the output of the other crank angle sensor.

(Example) Hereinafter, an example in which the present invention is applied to a type 6 DOHC engine will be described in detail with reference to the drawings.

As shown in FIG. 1, the left and right banks 1.2 of the engine E are provided with an exhaust camshaft 3 and an intake camshaft 4, respectively, and a crankshaft 6 is provided at the bottom of the cylinder block 5. . At the front end of each camshaft 3.4 is a cam pulley 7.
．． 8 are fixed to each other, and a crank pulley 9 is fixed to the vicinity of the front end of the crankshaft 6. These cam pulleys 7.8 and crank pulleys 9 have guide pulleys 1
A timing belt 11 guided at 0 is suspended, and a crankshaft 6 is mounted on each camshaft 3.4 in a clockwise direction in FIG.
The timing belt 1 rotates once during the rotation period.
1 to the crankshaft 6.

A belt cover 12 is attached to the front end of the engine E, and covers the pulleys 7 to 10 and the timing belt 11.
The crankshaft 6 extends forward through the belt cover 12, and has a plurality of pulleys 13 fixed to its front end for driving auxiliary equipment such as an alternator and a fan (see FIG. 2).

Inside the belt cover 12 near the crankshaft 6 is a first crank angle detector 1 for detecting the rotation angle of the crankshaft 6.
4, and a distributor 15 is provided on the front end surface of the belt cover 12 corresponding to the exhaust camshaft 3 of the right bank 2. This distributor 15 includes a second crank angle detector 16 for detecting the rotation angle of the exhaust camshaft 3, and a compression T of a reference cylinder (for example, the first cylinder).
Reference crank angle detector 17 for detecting DC timing
and is provided.

As shown in FIGS. 1 and 2, the first crank angle detector 14 includes a disk-shaped disk plate 18 fixed to the front end surface of the crank pulley 9, and the peripheral edge of the disk plate 18. Twelve detected portions 19 are provided protrudingly at equal angular intervals. Further, on the front end surface of the cylinder block 5, there is provided a first crank angle sensor 20 of an electromagnetic pickup type that faces the disk plate 18 from the outside.
The first crank angle sensor 20 outputs an electric signal in response to changes in magnetic flux caused by the approach and separation of the detected portion 19 of the disk plate 18.

Since the first crank angle detector 14 is located in the lower part of the engine room, dust and mud may adhere to the disk plate 18 and the first crank angle sensor 20 during driving. Since it is constructed according to the formula, sufficient reliability is ensured.

Next, the second crank angle sensor detector 16 will be explained. As shown in FIGS. 1 and 3, the front end of the exhaust camshaft 3 of the right bank 2 is connected to the rotation of the distributor 15 via a connecting member (not shown). It is connected to the shaft 21.

A disk-shaped disk plate 22 is provided at the front end of the rotating shaft 21.
is fixed to the peripheral edge of this disk plate 22,
Twelve slits 23 are formed radially at equal angular intervals. Further, a bifurcated sensor support member 25 is provided in the casing 24 of the distributor 15, sandwiching the disk plate 22 therebetween, and a second crank angle comprising a Hall element 26 and an electromagnet 27 is provided at the end of the sensor support member 25. A sensor 28 is provided. Hall element 26
and electromagnet 27 are arranged to face each other with the disk plate 22 in between, and the Hall element 26 detects the magnetic field passing through the slit 23 of the disk plate 22 and outputs a rectangular wave-like pulse signal. Note that this second crank angle detector 1
6 is disposed in the upper part of the engine room and is also installed inside the distributor 15, so there is no fear that dust or mud will adhere to the slit 23 or the Hall element 26 even when the vehicle is running.

Further explaining the reference crank angle detector 17,
As shown in FIGS. 1 and 3, one slit 23A of the 12 slits 23 formed in the disk plate 22 of the second crank angle sensor 16 is formed long in the radial direction, and the slit 23A is formed long in the radial direction. 2
A bifurcated sensor support member 29 that sandwiches the disk plate 22 is fixed to 4, and a reference crank angle sensor 32 comprising a Hall element 30 and an electromagnet 31 is provided on this sensor support member 29. The Hall element 30 and the electromagnet 31 are arranged to face each other with the disk plate 22 in between, and the Hall element 30 is inserted into the slit 23A of the disk plate 22.
It detects the magnetic field that passes through it and outputs a pulse signal. Note that the slit 23A is formed at a predetermined position corresponding to, for example, the compression TDC of the first cylinder.

Reference numeral 35 denotes a control unit mainly composed of a microcomputer for controlling the engine E. This control unit 35 includes a crank angle sensor 20, 28, a reference crank angle sensor 32, and signals from an ignition switch 36, a starter switch 37, etc. is input, and a control signal is output from the control unit 35 to the ignition unit, fuel injector 38, etc.

In the waveform shaping circuit included in the control unit 35, as shown in FIG.
The output signal from 0 is waveform-shaped using a threshold value α as a reference, and when the output signal is equal to or higher than the threshold value α, an rHJ level signal is output, and when it is less than the threshold value α, an rLJ level signal is output.

Next, the crank angle detection control routine executed by the control unit 35 will be described with reference to the flowchart shown in FIG.

First, in step S1, the ignition switch 36
When control is started with the ON operation of The second crank angle signal CA2 from the crank angle sensor 28 is read, and then in step S2 it is determined whether the meta 0 switch 37 has been turned on.

When the starter switch 37 is operated to start the engine E, the second crank angle signal C is input in step S3.
The engine speed Ne is calculated based on A2, and then in step S4, the engine speed Ne is set to 50Orpm.
It is determined whether N e <
Since it is 50 Orpm, the process advances to step S5. Since the second crank angle sensor 28 is a rectangular wave output type sensor consisting of a Hall element 26 and an electromagnet 27, it detects the rotation angle of the crankshaft 6 via the exhaust camshaft 3 even in the low rotation range. However, the first crank angle sensor 2
0 is an electromagnetic pickup type sensor, so 50Or
In the low rotation range below pm, the rate of change of magnetic flux is small, so it is not possible to obtain sufficient output, and as is clear from Figure 4, it is also possible to shape this weak sine wave signal into a rectangular wave signal. It's impossible.

Therefore, at the time of starting, the engine speed Ne is calculated based on the second crank angle signal CA2.

In step S5, it is determined whether there is an output from the first crank angle sensor 20, that is, whether an rHJ level signal is output from the waveform shaping circuit, and if "YES", the fail flag F is reset in step S6. It is (
F=O), IN OJ, fail flag F is set in step S7 (F=1). That is, when the engine speed Ne approaches 50 Orpm, the rate of change in magnetic flux increases, so the output from the first crank angle sensor 20 increases, and as shown in FIG. 4, the waveform shaping circuit changes the rHJ level signal. is output and the failsafe flag F is reset, but the first crank angle sensor 20
In the case of a failure such as a break in the signal line, the rHJ level signal is not output even if the engine speed Ne approaches 50 or 4, so in this case, the fail flag F remains set. Then, in the next step S8, the crankshaft rotation period is calculated based on the second crank angle signal CA2.

On the other hand, when the starter switch 37 is turned off or the engine speed Ne becomes 50 Orpm or more, the process proceeds to step S9, where it is determined whether or not the fail flag F has been reset, and if it has been set, the process proceeds to S8. If it has been reset, the process advances to SIO, where the crankshaft rotation period is calculated based on the first crank angle signal CAI.

By the way, as mentioned at the beginning, the second crank angle signal CA2, which is the output of the second crank angle sensor 28, is slightly different from the true crank angle of the crankshaft due to elongation of the timing belt, etc. There is a lag. In addition, the first crank angle signal CAL obtained by shaping the sine wave output of the first crank angle sensor 2° into a rectangular wave signal by a waveform shaping circuit may be slightly different from the true crank angle due to the waveform shaping processing time. There is a large time delay. FIG. 6 shows the delay times of both crank angle signals CAL and CA2 at each engine rotation speed Ne converted into crank angles.

As described above, the calculation result obtained in step SIO based on the signal CAL is corrected in step S11. This correction is based on the first crank angle signal CA, which increases as the engine speed Ne increases, as shown in FIG.
This is done according to the delay time of L. Further, for the calculation result obtained in step S8 based on the second crank angle signal CA2, both crank angle signals CAL, CA2
In step S1, correction is made according to the deviation of the time delay between
It is done in 2.

Table 1 shown below shows an example of a table created based on FIG. 6 and used for correction in steps Sll and S12. Note that the numerical values in the table are values obtained by converting the delay time into crank angle.

In Table 1, in other words, when the first crank angle sensor 20 is operating normally, the first crank angle signal CAL in Table 1 is corrected taking into account its delay time and is set as a set value in step S13. The first crank angle sensor 2
0 has failed, control may be performed in step 813 using the value obtained by subtracting the deviation of the delay time between both crank angle signals CAL and CA2 from the set value.

As is clear from the above description, the engine crank angle detection device according to the present embodiment includes the first and second crank angle sensors 20 and 28, and both crank angle sensors 20 and 28.
0.28, respectively, so that even if the first crank angle sensor 20 fails, the second crank angle sensor 28 Accurate data for engine control can be obtained based on the output of

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall configuration diagram of the engine and control system, Fig. 2 is a cross-sectional view of the vicinity of the first crank angle detector, and Fig. 3 is a cross-sectional view of the vicinity of the first crank angle detector. Fig. 4 is a time chart of the first crank sensor output, Fig. 5 is a flowchart of the crank angle detection control routine, and Fig. 6 is a partially cutaway plan view of the vicinity of the crank angle signal. It is a graph showing delay time with respect to engine rotation speed. 3... Exhaust camshaft 6... Crankshaft 11.
...Timing belt 15...Distributor 20...First crank angle sensor 26...Hall element 28...Second crank angle sensor 35...Control unit 36...Ignition switch 37...Starter switch

Claims (3)

[Claims] 1. An engine crank angle detection device comprising a first crank angle sensor that detects a rotation angle of a crankshaft, and a second crank angle sensor that detects a rotation angle of a camshaft, the first and second crank angles being An engine crank comprising: a correction means for correcting a temporal deviation between outputs of the sensors; and a switching means for switching the corrected output of the first or second crank angle sensor according to conditions. Angle detection device. 2. It is equipped with a first crank angle sensor that detects the rotation angle of the crankshaft and a second crank angle sensor that detects the rotation angle of the camshaft, and when normal, the crank angle of the engine is determined based on the output of the first crank angle sensor. A crank angle detection device for detecting, comprising: a correction means for correcting a temporal deviation between the outputs of the first and second crank angle sensors, and a correction means for correcting the temporal deviation between the outputs of the first crank angle sensor, and A crank angle detection device for an engine, comprising a switching means for switching to the output of the second crank angle sensor after the deviation has been corrected. 3. Crank angle according to claim 1 or 2, wherein the correction means increases the amount of correction for the temporal deviation between the outputs of the first and second crank angle sensors in accordance with an increase in engine speed. Detection device.