JP3275334B2 - Internal combustion engine speed detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an electronically controlled diesel engine in which the number of revolutions of an internal combustion engine is improved in which means for detecting a failure such as a disconnection of a revolution sensor set for detecting the number of revolutions is improved. It relates to a detection device.

[0002]

2. Description of the Related Art In a control system for a diesel engine, a rotary gear having a plurality of teeth formed around the rotary gear is driven to rotate coaxially with the engine, and the teeth are passed close to the peripheral surface of the rotary gear. 2. Description of the Related Art There has been known a rotation number detecting means in which a rotation sensor for electromagnetically detecting is provided.

[0003] As means for judging a failure such as a disconnection of the rotation sensor constituting such a rotation speed detecting means, when a detection signal from the rotation sensor is not detected for a specified period, it is determined that the rotation sensor is faulty. It is common to make a decision. Further, as disclosed in, for example, Japanese Utility Model Laid-Open Publication No. Sho 60-25966, it has been considered that the winding circuit of the rotation sensor is switched to another circuit and its resistance value is measured to determine the failure of the rotation sensor.

[0004] However, it is impossible for the means for judging the state in which the detection signal from the rotation sensor is not detected to judge what is the cause of the failure mode.
In the means for determining a failure by another circuit, circuit elements other than the rotation sensor are required,
Naturally, the configuration becomes complicated. Further, these failure determination means cannot determine an initial failure, and have a drawback that the failure can be detected only in a state where the failure has progressed to some extent.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can reliably detect the occurrence of a failure in a rotation sensor from an initial state. It is an object of the present invention to provide an internal combustion engine rotation speed detection device that ensures that control is executed with reliability.

[0006]

According to the present invention, there is provided a rotational speed detecting device for an internal combustion engine, which is driven coaxially with the internal combustion engine to form missing teeth corresponding to respective cylinders of the engine. An internal combustion engine provided with a rotation sensor that is set close to the peripheral surface of the rotary gear and detects passage of teeth of the rotary gear, and a reference position detection sensor that generates a signal corresponding to the top dead center position of the internal combustion engine The control device detects a missing tooth based on the detection signal from the rotation sensor, and determines whether or not the position where the missing tooth exists is in a specific area corresponding to the top dead center position. .

[0007]

In a control device for an internal combustion engine, a missing tooth position of a rotating gear is detected based on a detection signal from a rotation sensor,
By recognizing the number of detection pulses with reference to the missing tooth position, for example, fuel injection timing control is performed. Therefore, if a missing tooth is detected at a position other than the normal missing tooth position due to disconnection of the rotation sensor or the like, normal fuel injection control cannot be performed.

The missing tooth position is set corresponding to each cylinder of the internal combustion engine, and the missing tooth position is set corresponding to the specified crank angle position of each cylinder. Therefore, it is determined that there is an abnormality in the detection signal from the rotation sensor in a state in which two or more missing teeth are recognized based on the detection signal from the rotation sensor between the top dead centers, and the failure of the rotation sensor is determined. Mode can be set. In this case, if a missing tooth is detected in the specified range, the output of the rotation sensor is determined to be insufficient, and if a missing tooth is detected in a region other than the specific region, a disconnection failure of the rotation sensor may occur. It is determined and the failure mode is set.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an electronically controlled diesel engine. A diesel engine 11 includes an air cleaner 12.
Is supplied.

Downstream of the air cleaner 12, an intake air temperature sensor 13 for detecting the temperature of the intake air is provided.
A turbocharger 14 utilizing exhaust gas energy is provided downstream of the intake air temperature sensor 13, and a wastegate 15 for preventing an excessive increase in the supercharging pressure is provided downstream of the turbocharger.

A venturi 16, which is a passage of the air sucked from the air cleaner 12, is provided with an intake throttle valve 18 that is driven in accordance with the depression operation of an accelerator pedal 17. The corresponding accelerator opening Accp is detected by an accelerator position sensor 19. An intake pressure sensor 20 that detects the pressure of intake air is provided downstream of the intake throttle valve 18.

Cylinder head 11 of diesel engine 11
1 is provided with a fuel injection nozzle 21 and a glow plug 22 such that the tip protrudes into the engine combustion chamber 112. The cylinder block 113 of the diesel engine 11 is provided with a water temperature sensor 23 for detecting the temperature of engine cooling water, and a reference position sensor 24 for detecting a rotation reference position corresponding to the crank angle of the engine 11. Provided.

The fuel is supplied from the fuel injection pump 30 to the fuel injection nozzle 21 under pressure. This fuel injection pump 30 includes a pump drive shaft 31 that is rotated in conjunction with rotation of the crankshaft of the diesel engine 11,
A feed pump 32 (shown in a 90-degree development in this figure) for pressurizing the fuel is provided in connection with the pump drive shaft 31, and a large number of teeth are formed on the peripheral surface thereof. A rotary gear 33 having missing teeth corresponding to each cylinder is provided. The feed pump 32 and the rotary gear 33 are directly driven to rotate by the pump drive shaft 31.

At a position close to the outer peripheral surface of the rotary gear 33,
A rotation sensor 35 configured by an electromagnetic pickup attached to the roller link 34 is provided, and the rotation gear 33 rotates,
Each time the tooth passes close to the rotation sensor 35, a pulse-like detection signal is output.

A face cam 36 is further provided on the pump drive shaft 31.
The face cam is provided with the rotation of the drive shaft 31.
By rotating 36, the plunger 37 is reciprocated in the direction of the axis. The timing of the reciprocating operation of the plunger 37 is determined by the rotation angle position of the roller link 34, and the rotation angle position of the roller link 34 is determined by a timer piston 38 (shown in FIG. Is controlled by the change. The position of the timer piston 38 is controlled by a timing control valve 39 (TCV), and the timing control valve 39 controls the fuel injection timing.

A spill port 40 is set corresponding to the plunger 37, the operation timing of which is controlled by the timer piston 38. The fuel spill time from the plunger 37 is controlled by an electromagnetic spill valve 41. The injection amount is controlled. And plunger
The fuel pumped in response to the operation of 37 is discharged through a delivery valve 42 for preventing the fuel from flowing backward or drooping, and is supplied to the fuel injection nozzle 21 set in the diesel engine 11.

An intake air temperature sensor 13, an accelerator position sensor 19,
Intake pressure sensor 20, accelerator position sensor 19, water temperature sensor 2
3. Further, a detection signal from the rotation sensor 35 and the like is supplied to a control circuit 43 which is an electronic control unit. This control circuit
In 43, an input signal from each sensor is processed, and a timing control valve is output by an output signal from the control circuit 43.
39, the electromagnetic spill valve 41 and the like are controlled.

FIG. 2 shows the configuration of the control circuit 43. This control circuit 43 is composed of a microcomputer, and includes a central processing unit 51 (CPU) and a ROM 52 for storing a control program and various data. , CP
RAM5 for temporarily storing operation data and the like in U51
3. It is composed of a clock oscillator 54 for generating a clock signal and the like.

An intake air temperature sensor 13, an accelerator position sensor 19,
Detection signals from the intake pressure sensor 20, the water temperature sensor 23, and the like are input via buffers, respectively, and supplied to the multiplexer 55. In this multiplexer 55,
The input signals from the sensors are selected and output in order and supplied to the A / D converter 56. The input data from each sensor converted into digital data by the A / D converter 56 is input to the A / D converter 56. It is supplied to the output port 57. The input / output port 57, the CPU 51, the ROM 52, the RAM
The connection between 53 is made by a data bus 58.

The rotation sensor 35 and the reference position sensor 24 output pulse-like detection signals, respectively.
The pulse signals from these sensors 35 and 24 are subjected to waveform shaping by waveform shaping circuits 59 and 60, respectively.
It is taken into PU51.

The CPU 51 computes and outputs control signals for the timing control valve 39, the electromagnetic spill valve 41, and the like based on these input data. Valve 39
And, it is supplied to the electromagnetic spill valve 41 as a drive command signal.

FIG. 3 shows a control timing chart of the control system for the internal combustion engine configured as described above, in which the fuel injection of the diesel engine 11 is controlled. First, when the diesel engine 11 is rotated and the pump drive shaft 31 of the fuel injection pump 30 is rotated, the rotary gear 33 is rotated, and a pulse signal corresponding to each tooth formed around the rotary gear 33 is rotated. Output from the sensor 35.

Since the rotary gear 33 has missing teeth corresponding to the respective cylinders of the diesel engine 11, the rotation pulse output from the rotation sensor 25 includes a missing tooth portion. A correspondingly wide pulse signal is output, and this missing tooth is recognized.

The position of the missing tooth sets one reference position for fuel injection control. As shown in the figure, a pulse number is assigned to a rotation pulse generated after recognition of a missing tooth. it can. In this embodiment, a pulse number “0” is assigned to the rotation pulse after the missing tooth recognition, and the pulse number “13” is set to be the next missing tooth pulse.

That is, by identifying this pulse number, the rotation speed of the engine 11 and the accelerator pedal
The off-time of the electromagnetic spill valve 41, which is determined based on the accelerator opening corresponding to the amount of depression of 17, is determined. Further, since the position where the rotation pulse is generated and the relative position of the face cam 36 are constant, the amount of fuel injection is controlled by the OFF timing of the electromagnetic spill valve 41.

The fuel injection timing is controlled by a timing control valve.
This is executed by changing the position of the timer piston 38 by changing the energization time (duty ratio) of the timer 39. That is, by changing the position of the timer piston 38, the position where the rotation pulse is generated is changed,
Therefore, the relative position with respect to the detection signal corresponding to the top dead center (TDC) generated by the reference position sensor 24 on the engine 11 side is changed, and the injection timing control is performed.

The actual rotational speed of the diesel engine 11 changes so as to be lowest at the top dead center (TDC) position as shown in FIG.
Is turned off upon detection of the rotation pulse with the identification number “5”,
The ON control is performed by the identification number “9”.

Here, for example, when a failure such as an instantaneous disconnection occurs in the rotation sensor 35, as shown in FIG. 4, the rotation pulse becomes absent similarly to the missing tooth, and the missing tooth is detected. When the rotation sensor 35 is normal, the electromagnetic spill valve 41 is turned off in response to the fifth rotation pulse based on the required injection amount as shown in FIG. Is turned on in response to the rotation pulse of.

However, when a failure such as an instantaneous disconnection of the rotation sensor 35 occurs, a failure corresponding to the instantaneous disconnection of the rotation sensor 35 occurs between rotation signals corresponding to regular missing teeth as shown in FIG. This means that a tooth condition has occurred and a missing tooth due to erroneous detection has occurred. Therefore, the identification number of the rotation pulse is initialized by the detection of the erroneous missing tooth, and the rotation pulse next to the erroneous missing tooth is numbered "0". It will be.

Further, in such a situation, the rotation pulse "9" does not exist, so that the electromagnetic spill valve 41 is kept in the off state until the next injection. Therefore, a non-injection state is set. Also, in the injection timing control, since the number of the rotation pulse is incorrectly detected, the relative position of the rotation pulse is shifted. For this reason, when the rotation sensor 35 fails, the fuel injection amount and the injection timing cannot be controlled.

When an output failure from the rotation sensor 35 having a low output level occurs, if the rotation sensor 35 is constituted by an electromagnetic pickup,
In particular, when the rotation speed of the engine 11 is low, the output level of the sensor 35 decreases, and the state becomes the same as when the missing tooth is erroneously detected.

FIG. 6 shows a timing chart in such a state. Normally, the rotational speed of each cylinder of the engine 11 becomes the smallest near the top dead center (TDC).
Therefore, in the failure mode in which the output of the rotation sensor 35 is insufficient, a state in which the rotation pulse is not output due to the insufficient output of the sensor 35 occurs near the rotation pulse “4” near the top dead center (TDC). Then, the missing tooth is erroneously detected in a state where the rotation pulse is not output, and the same problem as in the case of the disconnection of the rotation sensor 35 occurs.

In the rotation speed detecting device according to this embodiment, when such a missing tooth is erroneously detected,
It is to determine whether or not the number of the rotation pulse is normal based on the top dead center (TDC) signal. If an erroneous missing tooth is detected near the top dead center (TDC) of the engine 11,
In addition to determining that the output of the rotation sensor 35 is insufficient, when an erroneous missing tooth is detected in other places, it is determined that the rotation sensor 35 has a failure such as disconnection.

FIG. 7 shows the flow of processing in the control circuit 43 for determining the failure of the rotation sensor 35. First, in step 100, missing teeth are detected two or more times between the top dead center (TDC) signals. Is determined. If the missing tooth signal is generated only once between the top dead center (TDC) signals, it is determined that a normal rotation pulse has been detected from the rotation sensor 35, and this processing ends as it is.

If the missing tooth is detected twice or more between the top dead center (TDC) signals in step 100, the rotation sensor 35
In this case, the process proceeds to step 101 and the top dead center (T
DC) signal is counted, and the rotational speed Ne of the engine 11 is calculated. Then, in the next step 102, the calculated rotation speed Ne is compared with a set value A (rpm) to determine a state in which the engine 11 is rotating at an extremely low speed. Then, in the state of the extremely low speed rotation, this processing is ended in order to prevent the occurrence of an erroneous determination at the extremely low speed.

At step 102, the engine 11
If it is determined that the motor is rotating at a rotation speed of (rpm) or more, the routine proceeds to step 103, where the position at which the rotation pulse is missing is detected. In step 104, it is determined whether or not the position of the detected missing tooth is the area B shown in FIG. 3 near the top dead center (TDC). Specifically, it is determined whether or not the pulse number is in the range of “3 to 8”.

In step 105, when a missing tooth occurs in the area B, the counter n is incremented.
In the next step 106, it is determined whether or not the count value of the counter n, that is, whether the number of missing teeth has occurred C times or more in the B region.

In the area B, where the output level of the rotation sensor 35 is inevitably reduced, when the number of missing teeth occurrences in the area B is determined to be C or more, the output of the rotation sensor 35 is reduced. It can be determined that the failure is insufficient. Therefore, in the next step 107, the output shortage of the rotation sensor 35 is determined.

If it is determined in step 104 that the missing tooth position is outside the area B, then in step 108 the number of occurrences is counted by the counter n. The count value of the counter n is compared with the set value D in the next step 109. If it is determined that the number of missing teeth is equal to or more than D, the process proceeds to step 110.
Is determined as a disconnection failure of the rotation sensor 35. Here, if the relationship between the set values C and D in steps 106 and 109 is set so as to satisfy the relationship of "C>D", such a failure determination can be reliably performed.

[0040]

As described above, according to the apparatus for detecting the rotational speed of an internal combustion engine according to the present invention, the position of the missing tooth corresponding to each cylinder is detected based on the output of the rotational pulse from the rotational sensor. In addition, failures such as insufficient output of the rotation sensor and disconnection can be quickly detected depending on the occurrence state of the missing teeth. Therefore, when performing electronic control of the internal combustion engine that is performed using the output from the rotation sensor, a failure of the rotation sensor is quickly found, and a means for avoiding a state in which the engine cannot be controlled is provided. It can be started effectively, and the reliability of the electronic control of the internal combustion engine is reliably and effectively improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a control unit of a diesel engine for explaining an electronically controlled rotation speed detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a control circuit of the embodiment.

FIG. 3 is a diagram showing a timing chart of a detection signal and the like in a control unit of the engine.

FIG. 4 is a diagram showing an output signal and a rotation pulse when an instantaneous disconnection occurs in a rotation sensor.

FIG. 5 is a timing chart when the instantaneous disconnection occurs.

FIG. 6 is a timing chart showing a rotation sensor output shortage state.

FIG. 7 is a flowchart illustrating a flow of processing in a control circuit that diagnoses a rotation sensor.

[Explanation of symbols]

11 ... diesel engine, 13 ... intake temperature sensor, 17 ... accelerator pedal, 18 ... intake throttle valve, 19 ... accelerator position sensor, 20 ... intake pressure sensor, 21 ... fuel injection nozzle, 23 ... water temperature sensor, 24 ... reference position sensor , 30 ... Fuel injection pump, 31
... Pump drive shaft, 33 ... Rotary gear, 35 ... Rotation sensor, 38 ...
Timing piston, 39: timing control valve, 41: electromagnetic spill valve, 43: control circuit.

Claims (1)

(57) [Claims] 1. A rotary gear that is rotationally driven coaxially with an internal combustion engine and has missing teeth corresponding to each cylinder of the engine, and a rotary gear set near the peripheral surface of the rotary gear. A control device for an internal combustion engine, comprising: a rotation sensor that detects the passage of a tooth; and a reference position detection sensor that generates a signal corresponding to the top dead center position of the internal combustion engine. A missing tooth detecting means for detecting a tooth, and determining whether or not to count two or more missing teeth between the detection signals from the reference position detecting sensor based on a detection signal from the missing tooth detecting means. A missing tooth position determining unit that determines whether the missing tooth position is present in a specific area corresponding to the top dead center based on a missing tooth detection signal from the missing tooth detection unit. Determining means and the missing tooth number determining means The number of missing teeth is a coefficient.
When the state where the toothless position exists in the specific area is determined by the missing tooth position determining means, a first failure judgment means for judging an output shortage of the rotation sensor, the toothless The number of missing teeth of two or more is a coefficient
A second failure determination unit configured to determine a failure of the rotation sensor or the like in a state where the missing tooth position is determined to be outside the specific area by the missing tooth position determination unit, A rotation speed detection device for an internal combustion engine, wherein a failure mode of the rotation sensor is set by the first and second failure determination means.