JP2545875B2 - Crank angle detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crank angle detecting device,
In particular, the present invention relates to a crank angle detection device having a function of determining abnormality.

[Prior Art] In order to electrically control the ignition timing and the fuel injection amount of each engine for each cylinder, it is necessary to detect the crank angle corresponding to each process from intake to exhaust of the engine.

Various types of crank angle detecting devices for detecting the crank angle have been known, and are disclosed in Car Electronics Introduction (September 25, 1984, Keigaku Shuppan Co., Ltd.), pp. 135-145. In addition to the one that directly detects the crank angle from the rotation of the crankshaft,
There is also one that detects the crank angle from the rotation of a cam shaft mechanically linked to the crank shaft. One of the latter types is disclosed in Japanese Patent Laid-Open No. 58-167881, which detects the crank angle from the rotation of a distributor shaft.

However, the camshaft is rotated by the crankshaft via a gear, a belt, a chain, etc., and drives the intake / exhaust valve and the distributor. Therefore, if the crank angle is detected from the rotation of the camshaft, the position where the detection signal is generated fluctuates due to the effects of shaft twist, gear backlash, timing belt deflection, etc. .

On the other hand, when directly detecting the crank angle from the rotation of the crankshaft, there is no such problem, but
In the case of a cycle engine, the crankshaft makes two revolutions to complete the entire process from intake to exhaust, so even if the top dead center of one cylinder is detected as the reference position by the rotation of the crank shaft, that top dead center is detected. Cannot distinguish between exhaust top dead center and compression top dead center.

Therefore, it is conceivable that a unit rotation angle of, for example, 30 degrees of the crankshaft is detected by the rotation of the crankshaft, and a reference position of 720 degrees is detected by the rotation of the camshaft (for example, Japanese Patent Laid-Open No. 213714 publication).

For example, as shown in FIG. 6 (A), the reference signal G for every 720 ° CA is different from the unit angle signal Ne for every 30 ° CA, and the unit angle signal Nes corresponding to the compression top dead center of one cylinder is Nes. The position of the unit angle signal Ne generated immediately after the reference signal G is detected as the reference position Nes for crank angle detection by setting so as to occur in a predetermined range between the unit angle signal A and immediately before that. To do.

However, the generation position of the reference signal G is, as described above,
It fluctuates due to factors such as shaft twist, gear backlash, and timing belt flapping.

Further, as shown in FIG. 6 (A), the fluctuation range of the generation position of the reference signal G is small at ± α at low speed and idling, and large at ± β (β >> α) at high rotation and high load. And changes.

Therefore, as shown in FIG. 6 (A), in order to accurately detect the reference position Nes of the crank angle even if the position where the reference signal G is generated fluctuates significantly by ± β as in the case of high rotation and high load,
The reference signal G is designed to fluctuate around a center between the reference position Nes of the crank angle and the unit angle signal A immediately before it.

[Problems to be Solved by the Invention] However, in the crank angle detecting device as described above, the camshaft and the crankshaft are not correctly linked, for example, the groove of the timing belt is linked with one tooth. Even when the rotation speed is low and the load is low, the fluctuation range of the reference signal G is as small as ± α, and the crank angle reference signal Nes is correctly determined as shown in FIGS. 6 (B) and 6 (C).

However, since the fluctuation range of the reference signal G is as large as ± β at high speed and high load, the reference position of the crank angle is deviated and detected. In the example of abnormality 1 in FIG. 6 (B), when the generation position of the reference signal G deviates to Ga, the reference position of the crank angle is detected at a position A advanced by 30 CA from the correct position Nes. . Further, in the example of abnormality 2 in FIG. 6 (C), when the generation position of the reference signal G is deviated to Gb, the reference position of the crank angle is detected at the position B delayed by 30 ° CA from the correct position Nes. Will end up. In any case, since the fuel injection control and the ignition timing control are performed by inputting the crank angle reference position, the abnormal fuel injection control and the ignition timing control are performed, and the engine malfunctions. In some cases.

That is, the crank angle detecting device as described above correctly determines the reference position Nes of the crank angle for low rotation, low load, etc. even if the mounting of the timing belt or the like is abnormal as described above. Therefore, the driver or maintenance person often does not notice the abnormality.

[Means for Solving the Problems] The present invention detects the gap between the reference signal G and the unit angle signal Ne to detect the abnormal state before the reference position Nes of the crank angle is erroneously determined. Is performed to prevent engine malfunction due to erroneous determination of the crank angle reference position.

The present invention has the object of solving the above problems and employs the following configuration as illustrated in FIG.

That is, the gist of the present invention is that the unit angle signal generator M2 that generates a unit angle signal for each unit rotation angle of the crankshaft M1 and one rotation of the camshaft M3 that mechanically interlocks with the crankshaft M1. Reference signal generator that generates a reference signal for each
In the crank angle detecting device configured to include M4, the position where the reference signal is generated is near an intermediate position between a predetermined unit angle signal and a unit angle signal generated next to the unit angle signal, Further, from the unit angle signal generated by the unit angle signal generator M2, a detection unit M5 for detecting the generation position of a predetermined reference unit angle signal, and a reference unit obtained by the detection unit M5 The distance detection means M6 for detecting the distance between the generation position of the angle signal and the generation position of the reference signal generated by the reference signal generator M4, and the distance detected by the distance detection means M6 are predetermined. A crank angle detecting device is provided with an abnormality determining means M7 for performing an abnormality determination and outputting a result when it is out of a predetermined range.

Here, as the unit angle signal generator M2 and the reference signal generator M4, a position sensor using an electromagnetic pickup that has been conventionally used, a position sensor using a Hall element,
An optical position sensor or the like can be used.

Further, the predetermined range used in the abnormality determination means M7, the generation position of the reference signal generated by the reference signal generator M4,
This is the range in which the reference position of the crank angle is not erroneously detected even if it changes due to the various causes described above.

[Operation] The operation of the present invention will be described using an example of the time chart of FIG.

The present invention relates to a unit angle signal Ne of a crankshaft M1 detected by a unit angle signal generator M2 and a reference position signal generator.
A crank angle detecting device for detecting a reference position Nes of a crank angle by using a reference signal G of a camshaft M3 detected by M4, and a unit angle signal Ne at a position separated from the reference signal G by a predetermined angle. Crank angle reference position
It is a crank angle detection device called Nes. For example, in FIG. 2, the unit angle signal Ne generated immediately after the reference signal G is used as the reference position Nes of the crank angle.

When the distance g between the reference unit angle signal detected by the detecting means M5 and the reference signal G is detected by the distance detecting means M6, and the distance g is outside the predetermined range by the abnormality determining means M7. Then, it is determined to be abnormal. Here, the reference unit angle signal is a unit angle signal Ne located at a position separated from the reference signal G by a predetermined angle. For example, in FIG. 2, the unit angle signal Nes generated immediately after the reference signal G is shown. Is the reference unit angle signal.

In the example of FIG. 2, the reference unit angle signal and the reference position of the crank angle are both Nes, but they do not necessarily have to match. Further, as the reference unit angle signal or the reference position of the crank angle, in addition to Nes, the unit angle signal Neb immediately before the reference signal G,
The unit angle signal Nea two before the reference signal G or the unit angle signal Nec two after the reference signal G can be used.

In the example of FIG. 2, when the distance g is out of the predetermined range ab, that is, when g> a or g <b, the abnormality determination means M7 determines the abnormality. In FIG. 2, the predetermined ranges a to b are drawn so as to be wider than the range of ± β described above, but these a and b may be set according to the state of the engine that determines abnormality.

That is, if the distance g is within the predetermined range,
Even if the engine becomes high-speed / high-load and the fluctuation range of the reference signal G becomes as large as ± β described above, the reference signal G is generated next to the predetermined unit angle signal (Neb in the example of FIG. 2) and then. Between the unit angle signal (Nes in the example of FIG. 2)
Crank angle reference position Nes is not erroneously determined.

However, if the distance g is out of the predetermined range, the reference position Ne of the crank angle will be correct at low rotation and low load.
Even if s is determined, the crankshaft M1 and the camshaft M3 are not correctly linked, so high rotation /
The crank angle reference position is erroneously determined when the load is high (see FIG. 6).

Therefore, the reference position of the crank angle is actually detected by detecting whether the gap g between the reference signal G and the reference unit angle signal is within the predetermined range (ab in the example of FIG. 2). The anomaly can be determined before erroneously determining. Therefore, it is possible to prevent engine malfunction due to engine control being performed in an abnormally advanced or retarded state due to an incorrect determination of the crank angle reference position.

[Embodiment] FIG. 3 is a schematic view of an engine in which the crank angle detecting device of the embodiment is mounted and its surroundings.

 Hereinafter, a description will be given based on this drawing.

This engine has a fuel injection valve 10 for injecting fuel into the intake air of the engine body 5, a throttle valve 12 and an ignition plug 15, and an oxygen sensor provided in an exhaust pipe 20 for detecting the residual oxygen concentration in exhaust gas. 25, a water temperature sensor 30 that detects the cooling water temperature of the engine body 5, an air flow meter 40 that detects the amount of air taken into the intake pipe 35, and an intake air temperature sensor that detects the temperature of the intake air sent to the engine body 5. 45, an igniter 50 that outputs a high voltage required for ignition of the spark plug 15, and a distributor 60 that is interlocked with the crankshaft 55 and distributes and supplies the high voltage generated by the igniter 50 to the spark plug 15.

Further, the crankshaft 55 and the camshaft 65 are connected by a timing belt 70 so that the camshaft 65 rotates once when the crankshaft 55 rotates twice.
Further, this engine includes a rotation angle sensor 75 that outputs a rotation angle signal Ne every time the crankshaft 55 rotates 30 degrees,
It also includes a reference position sensor 80 that outputs a reference position signal G each time the camshaft 65 makes one revolution. In the present embodiment, the output position of the rotation angle signal Ne immediately after the reference position signal G is set to indicate the compression top dead center of the first cylinder, and this position is set as the crank angle reference position Nes.

Then, the fuel injection valve 10, the oxygen sensor 25, the water temperature sensor 30, the air flow meter 40, the intake air temperature sensor 45, the igniter 50, the rotation angle sensor 75, the reference position sensor 80, and the like are connected to the electronic control circuit 100, respectively. There is.

The electronic control circuit 100 includes a well-known CPU 105, ROM 110, RAM
115, a backup RAM 117 as the center of the logic circuit, and an input / output circuit (I / O) 120 for performing input / output with the outside, a timer
122 is provided, and these are connected to each other by a common bus 125.

The CPU 105 inputs signals from the oxygen sensor 25, the water temperature sensor 30, the air flow meter 40, the intake air temperature sensor 45, the rotation angle sensor 75, the reference position sensor 80 and the T terminal 130 via the I / O 120. The T terminal 130 changes the control mode of the electronic control circuit 100. When the T terminal 130 is turned on, the electronic control circuit 100 tests each function of the engine and the like. Is output from the output terminal 132.

Then, based on these signals and the data in the ROM 110, RAM 115, the CPU 105 outputs a drive signal to the fuel injection valve 10 and the igniter 50 via the I / O 120 to control the engine body and detects any abnormality. A warning is issued to the driver through the abnormality display lamp 135, and the abnormality is stored in the backup RAM 117. The information stored in the backup RAM 117 can be read from the output terminal 132 by a predetermined operation.

Further, in the present electronic control circuit 100, any unit angle signal may be used as the reference unit angle signal, but in the present embodiment, as will be described later, the unit angle signal Ne immediately after the reference position signal G is used.
Use s as the reference unit angle signal.

Next, the abnormality determination processing performed in the electronic control circuit 100 described above will be described.

In the crank angle detection device of the present embodiment, a mode for determining an abnormality when performing a maintenance inspection at a repair shop (hereinafter referred to as an inspection mode) and a mode for determining an abnormality when the vehicle is traveling (hereinafter referred to as a traveling mode) There are two modes.

Switching between the modes is performed by a T terminal 130 connected to the electronic control circuit 100. When the T terminal 130 is on, the inspection mode is set, and when it is off, the traveling mode is set.

First, the inspection mode will be described with reference to the flowchart of FIG. This process is executed, for example, every predetermined time (8 msec).

When this process is started, first, at S200, the T terminal 13
Determine if 0 is on. If it is not on, the process is terminated without executing the inspection mode.

When the T terminal 130 is on, it is determined at S210 whether the engine is idling or not.
This is because in the idling state, the timing belt does not flutter and the abnormality can be determined more accurately. If it is determined in S210 that the engine is not in the idling state, in S220, the fact that the engine does not satisfy the abnormality determination condition of the crank angle detection device is output from the output terminal 132, and this processing ends.

On the other hand, if it is determined in S210 that the engine is idling, the reference position Nes of the crank angle and the generation position of the reference signal G are input in S230, and the reference position Nes of the crank angle and the reference position are input in S240. The distance g from the generation position of the signal G is calculated (see FIG. 2).

This gap g can be calculated, for example, as follows.

That is, in FIG. 2, assuming that the generation time of the unit angle signal Neb obtained by the timer 122 is T1, the generation time of the reference position Nes is T2, and the generation time of the reference signal G is T3, 30 ° CA
The time required for is T2-T1.

Therefore, Therefore, the deviation g (° CA) can be calculated by the following formula.

In subsequent S250, it is determined whether or not this gap g is within a predetermined range a1 to b1 (see FIG. 2). In the present embodiment, if the fluctuation of the reference signal in the idling state is ± 5 ° CA or less, it is determined that the crank angle detecting device is normal. Therefore, in the present embodiment, a1 = 15 + 5 = 20 ° CA, b1 = 15-5
= 10 ° CA.

If it is determined in S250 that the distance g is within the predetermined range (state of FIG. 2), in S260, the fact that the crank angle detection device is normal is output from the output terminal 132, and this processing is performed. To finish.

On the other hand, if it is determined in S250 that the gap g is outside the predetermined range, then in S270, the fact that the crank angle detection device is abnormal is output from the output terminal 132, and this processing ends.

An operator who is inspecting the crank angle detecting device of the present embodiment needs to inspect the mounting state of the timing belt and the like again when a signal indicating an abnormality is output from the output terminal 132.

In the present embodiment, the abnormality determination is performed only at the time of idling, but the abnormality determination may be performed at times other than idling by using a and b obtained from the map of the rotational speed and the load described later.

Next, the traveling mode will be described with reference to the flowchart of FIG.

This process is executed at predetermined intervals (for example, 8 msec).

When this processing is executed, first, in S300, the reference position Nes of the crank angle and the generation position of the reference signal G are input, and S
At 310, the distance g between the reference position Nes of the crank angle and the generation position of the reference signal G is calculated (see FIG. 2). Then, in S320, a and b used for the abnormality determination are obtained from a table (not shown) based on the engine speed and engine load (for example, Q / N, Q: intake air quantity, N: speed). This is because when the engine is at low speed and low load, the fluctuation of the reference signal is small because the flap of the timing belt is small and the range for judgment is, for example, ± 5 ° CA. When the load is high, the flap of the timing belt is large, and the range for judgment is, for example, ± 10 ° CA.
This is because it is necessary to

In subsequent S330, it is determined whether or not the gap g is within a predetermined range ab (see FIG. 2).

If it is determined in S330 that the distance g is within the predetermined range (state of FIG. 2), there is no abnormality in the crank angle detection device of this embodiment, so this process is performed without performing any process. finish.

On the other hand, if it is determined in S330 that the distance g is outside the predetermined range, in S340, the fact that the crank angle detection device is abnormal is stored in the backup RAM 117, and in S350, the abnormality display lamp 135 Is turned on to warn the driver, and in S360, the engine control is changed to an initial mode in which the engine control is executed without using the data such as the crank angle in order to prevent the engine from malfunctioning, and the process is terminated.

A driver of a vehicle equipped with the crank angle detecting device of the present embodiment needs to inspect the installation state of the timing belt at a repair shop or the like when the abnormality display lamp 135 is lit.

As described above, the crank angle detecting device according to the present embodiment can detect an abnormality before the reference position of the crank angle is erroneously detected when the timing belt is not properly attached.

Therefore, it is possible to prevent engine malfunction due to erroneous detection of the crank angle reference position, which is caused by operating the engine at high rotation and high load without noticing the abnormality of the timing belt or the like.

Although the two modes of the inspection mode and the traveling mode are used in this embodiment, the object of the present invention can be achieved by only one of the modes.

Also, if there are two modes as described above, the T terminal
Not only can you detect abnormalities by simply turning on 130, you can also detect abnormalities when the crankshaft and camshaft stop running during running.

[Effects of the Invention] The present invention adopts the configuration as described above,
When the timing belt is not properly attached, the abnormality can be detected before the crank angle reference position is erroneously determined.

Therefore, it is possible to prevent the engine from malfunctioning by operating the engine at high rotation and high load without noticing the abnormality of the timing belt or the like, and erroneously determining the reference position of the crank angle.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a time chart for explaining the present invention, FIG. 3 is a block diagram of an embodiment of the present invention, and FIGS. 4 and 5 are flow charts for explaining the operation thereof. , FIG. 6 is a time chart for explaining the prior art. M1,55 …… Crankshaft M2,75 …… Unit angle signal generator (unit angle sensor) M3,65 …… Camshaft M4,80 …… Reference signal generator (reference position sensor) M5 …… Detecting means M6… … Distance detection means, M7 …… Abnormality judgment means, 5 …… Engine body, 70 …… Timing belt, 100 …… Electronic control circuit, 135 …… Abnormality indicator lamp, 132 …… Output terminal

Claims (1)

(57) [Claims] 1. A unit angle signal generator for generating a unit angle signal for each unit rotation angle of a crankshaft, and a reference signal generation for generating a reference signal for each rotation of a camshaft mechanically interlocked with the crankshaft. In a crank angle detecting device configured such that the generation position of the reference signal is near an intermediate position between a predetermined unit angle signal and a unit angle signal generated next to the unit angle signal, Further, from the unit angle signal generated by the unit angle signal generator, a detecting unit that detects a generation position of a predetermined reference unit angle signal, and a reference unit angle signal obtained by the detecting unit. Distance detection means for detecting the distance between the generation position and the generation position of the reference signal generated by the reference signal generator, and the distance detected by the distance detection means is outside a predetermined range. Occasionally, performs an abnormality determination, a crank angle detecting apparatus characterized by comprising an abnormality judging means for outputting a result.