JPH0436259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for self-igniting internal combustion engines (diesel engines), in particular to a safety device for self-igniting internal combustion engines with sensors for measuring various operating characteristic quantities.

In the case of self-igniting internal combustion engines, monitoring the rotational speed is a very important issue. If the fuel supply amount is controlled mechanically for this purpose, a centrifugal force governor is used, which controls the injection amount when the rotational speed becomes higher or lower depending on the driving state. It is composed of

On the other hand, even when control is performed electronically, it is extremely important to process the rotation speed signal for safety reasons, so the signal from the rotation speed sensor must be a reliable signal. .

Conventional devices measure the rotational speed by measuring quantities related to the rotational speed instead of directly measuring the rotational speed (for example, devices disclosed in Japanese Utility Model Application Publication No. 156004/1983 and No. 124804/1989). ) is known, but since it is not configured to form an auxiliary signal related to the rotational speed and detect and compare the occurrence of both signals, it is not possible to reliably monitor the rotational speed sensor. In addition, when installing a sensor to detect an auxiliary signal and comparing its signal level with the signal level from the rotation speed sensor, a highly accurate auxiliary signal detection device and signal level comparison device are required, so the entire device is The problem is that it is complicated and expensive.

SUMMARY OF THE INVENTION Accordingly, the present invention aims to eliminate such conventional drawbacks and to provide a safety device for a self-ignition internal combustion engine that can monitor a rotational speed sensor by simple means and allow the internal combustion engine to operate safely. shall be.

To achieve this objective, the present invention provides a safety device for a self-igniting internal combustion engine for monitoring a rotational speed sensor, which detects a signal generated when the internal combustion engine is operating and obtained from a sensor other than the rotational speed sensor. Means for forming an auxiliary signal from signals relating to the start of injection, fuel supply amount, air amount, boost pressure, exhaust gas or power supply voltage, and whether a signal from a rotational speed sensor has occurred and whether said auxiliary signal has occurred; A configuration is adopted in which, after supplying starting fuel, emergency running operation is performed in accordance with the signal from the rotational speed sensor and the generation result of the auxiliary signal. Furthermore, the present invention provides a safety device for a self-ignition internal combustion engine for monitoring a rotational speed sensor, which includes means for generating a starter signal in accordance with operation of a starter of the internal combustion engine, and a signal from the rotational speed sensor. A configuration is adopted in which emergency running operation is performed in accordance with the signal from the rotational speed sensor and the result of generation of the starter signal.

According to such a configuration, detection of the auxiliary signal or starter signal obtained from a sensor other than the rotation speed sensor that monitors the rotation speed sensor can be accomplished by simply detecting whether or not the auxiliary signal or starter signal is generated. Since the circuit configuration is simple, the circuit configuration can be simplified. In addition, since only the signal from the rotation speed sensor and the generation results of the auxiliary signal or starter signal are checked, there is no need to compare the magnitude of each signal, and it is possible to check whether the rotation speed sensor is functioning normally using simple means. When an error occurs, appropriate measures such as emergency driving can be taken, making it possible to operate the internal combustion engine safely.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a schematic diagram of the main parts of an electronic control device for a diesel (self-ignition) internal combustion engine. The internal combustion engine is designated by the reference numeral 10 and has an intake pipe 11 and an exhaust pipe 12. In the region of the intake pipe 11, an air quantity sensor 13 as well as a supercharger 14 and a supercharging pressure sensor 15 are arranged. In the exhaust pipe 12, an exhaust gas sensor 17 (which detects exhaust gas temperature or exhaust gas composition) is arranged behind a turbine 16 connected to a supercharger 14. The fuel pump is designated by the reference numeral 19, and its outlet side is connected to the fuel supply pipe 2.
0 to an injection valve 21 with an injection start sensor 22 . Reference numeral 24 indicates a starter, reference numeral 25 indicates a generator, and reference numeral 26 indicates a rotational speed sensor, which detects the rotational speed of the internal combustion engine drive shaft 27 via an annular projection 28 . Further, the combustion chamber sensor is labeled with a number 29.

Further, each sensor, starter 24, and generator 25 are connected to a control device 30 that determines fuel supply data such as the amount of fuel supplied to the fuel pump 19 and the start of injection (SB).

What is important about the present invention is that the rotation speed sensor 2
With all sensors other than 6 it is also possible to obtain rotational speed-related (auxiliary) signals, by means of which the rotational speed sensor 26 is monitored. In this sense, the generator 25 can also be considered as a sensor, and the switching signal of the starter 24 likewise provides a corresponding comparison signal (auxiliary signal).

In the case of the configuration shown in FIG. 1, the injection start sensor 22 and the combustion chamber sensor 29 provide a signal that most closely approximates the rotational speed. This is because, in the case of a self-ignition internal combustion engine, as a result of injecting fuel into the cylinder, the rotational speed and injection correspond accurately, so that the injection start signal and the combustion chamber signal are the output of the rotational speed sensor 26. This is the most appropriate comparison signal for the value.

A safety device for monitoring the rotational speed sensor by detecting the injection start signal is illustrated as a flowchart in FIG. The internal combustion engine and the control device are designated by reference numeral 33 in FIG. The flowchart that follows is divided into two main parts, one of which is a starting program and the other is a cyclically continued operating program. In the starting program, the presence or absence of an output of a rotational speed signal is detected via a comparison signal from an injection start sensor. In detail, the flow is as follows as a specific example.

Block 34 supplies a predetermined amount of fuel during startup. In the subsequent block 35, the presence or absence of the output of the rotational speed signal is detected.

Correspondingly, the presence or absence of the output signal of the injection start sensor 22 is determined in the injection start signal detection block 36. Both detection blocks 35 and 36
The YES output is led to the AND gate 37, and if the output of the AND gate 37 is positive, then the normal running program is executed (block 38).

Furthermore, the injection start signal detection block 36 is YES.
A maximum value detection block 40 for limiting the rotational speed is connected to the output. If a maximum value is obtained, a corresponding reduction in the injected fuel takes place in the subsequent block 41.

Detection block 3 for rotational speed signal and injection start signal
Both outputs from 5 and 36 are further routed to truth table block 42 in FIG. On the signal lines 43, 44 from the truth table block 42, error signals relating to the speed sensor or the injection start sensor appear. These signal lines 43, 44 are led to an OR gate 45, whose positive output signal causes the fuel injected in the block 41 to be reduced (or cut off as the case may be). It is also possible to enter a block 38 corresponding to the normal driving program via the dashed line 46.

Each area of the truth table block 42 is labeled with a Roman numeral. In the region, the internal combustion engine is either not running or is running but no output signals from both sensors occur.
In this case, the normal program corresponding to block 38 is not executed.

In the region of truth table block 42, the internal combustion engine is being driven, but no output signal of the rotational speed sensor is generated. In this case, the fuel supply is reduced, resulting in emergency driving, or, if the supply is reduced to zero, the internal combustion engine is shut down. The region corresponds to a case where there is no output from the injection start sensor 22 but the internal combustion engine is operating. In this case, emergency driving operation is selected. The area indicates that the internal combustion engine is running and the sensors are operating correctly, so that a normal driving operation is programmed. This region corresponds to the output signal obtained from the AND gate 37.

In the case of normal driving, protection (in detection block 40) against overshooting of the rotational speed takes place via the injection start signal.

Therefore, what is important in the embodiment shown in FIG. 2 is that by using the injection start sensor 22 that emits a pulse every two revolutions of the crankshaft, a) a function check of the rotation speed sensor 26, and b) a check (monitoring) of the rotation speed. is what will be done.

The injection start signal also serves as an auxiliary signal indicative of the rotational speed signal, for reasons that are closely linked to the rotational speed signal. The same applies to the combustion chamber signal. If such a substitute signal is not available, another signal indicating that the internal combustion engine is being driven is used to monitor the rotational speed sensor 26.

Other auxiliary signals have various properties. In the flowchart of FIG. 3, the signal is labeled X _i . In FIG. 3, at block 50, signal X _i is compared to a threshold value X _is . When the signal reaches the threshold value, a rotational speed detection takes place in block 51. If the rotational speed is below a predetermined value ( _ns ), the injected fuel is reduced. Signal X _i
is lower than the threshold and the rotational speed is higher than the threshold, a program for normal driving is carried out.

A specific example of the flowchart shown in FIG. 3 will be explained with reference to FIG. In FIG. 4, the output signal of the generator 25 is shown diagrammatically as a function of time. It can be seen from the figure that the level of the output signal (X _i ) is relatively low when the starter is operating, and that the output signal increases when the internal combustion engine is subsequently operated normally. If the start fails, the generator 25
The output signal remains at a low level for a while, but then drops again. This is shown by the dotted line in FIG. In the case of X _i = U _batt (battery voltage), the monitoring mechanism that operates according to the flowchart in Figure 3 detects whether the value of the output signal X _i has reached the threshold value indicated by the horizontal line. be done.
The normal start program is executed unless the threshold value is reached. If the internal combustion engine is operating at a high rotational speed, the output signal X _i will be greater than this threshold and the rotational speed will subsequently be detected. If the rotation speed and output signal are appropriate,
The normal driving operation program corresponding to block 38 is activated. If the engine speed is lower than the threshold value (n _s ) and at the same time the battery voltage is high, this indicates that the engine speed sensor is malfunctioning, and as a result, corresponding to block 41, the injected fuel is reduced or will be cut off.

What has been said about the battery voltage in Figure 4 is the air flow meter 13 and boost pressure sensor 1 in Figure 5.
5. This also applies to the signals from the fuel supply meter and exhaust gas sensor 17.

FIG. 5 shows boost pressure (PL), air amount signal (QL), fuel supply amount signal (QK), and temperature (θ) in relation to the rotational speed. Each curve starts from the speed nLL during no-load operation. These signals may be used alone or in combination for monitoring.
Each signal has a threshold value (X _is ) appropriate for its characteristics, and when the threshold value is exceeded, the rotation speed sensor is checked, and when the maximum threshold value is reached, the rotation speed is Measures will be taken to prevent overflow.

The above comparison signals can be obtained synchronously with the rotational speed sensor signal (in the case of injection start sensor signals or combustion chamber sensor signals) or analog values (related to fuel supply, battery voltage, air volume, boost pressure, exhaust gas) However, the starter signal also contains predetermined information, and the safety device according to the present invention can be implemented using the starter signal as well. This is shown in Figures 6a and 6b.
This will be explained using figures. As shown in FIG. 6a, the presence or absence of the output of the rotational speed signal is detected after a predetermined time Δt has elapsed from the start time tein. If a rotational speed signal is output, a normal start program and a subsequent operating program are processed in the control device. On the other hand, when there is no output of the rotational speed signal, the current that controls the fuel supply amount control member of the injection valve is reduced. This is because in that case the rotational speed sensor 26 is probably out of order.

In contrast, FIG. 6b shows the detection associated with the end point Taus of the starter signal. The difference between the methods shown in Figures 6a and 6b lies in whether rotation speed detection is started by detecting the rising edge of the starter signal, or whether rotation speed detection is performed by detecting the falling edge of the starter signal. . In that case, in the case of the solution according to Fig. 6a, the delay time △t
must be formed.

Furthermore, the flowchart shown in FIG. 7 is for performing a functional test of the rotational speed sensor before each start, and in this case, the test is performed by regarding the start of fuel supply at the time of start as the start. The flowchart is divided into a starting program and a subsequent periodic operating program. Block 60 shows the operation of starter 24. This is followed by a rotational speed minimum value detection block 61, in which no starting fuel is supplied as long as the rotational speed n does not reach the minimum rotational speed n _Mio (block 62). Only when the rotational speed exceeds the minimum value does a fuel increase take place, so that block 63
Start-up concentration is carried out via the On the other hand, this is followed by a rotational speed detection (block 64), and starting fuel is supplied until the detected rotational speed value does not reach _n1 . However, when this value is reached, the normal operating program is executed. In the flowchart of FIG. 7, a rotational speed detection block 65 is connected before the normal program block 38, but this block 65 is placed within the normal program loop 66. If for some reason the output of the rotational speed signal suddenly disappears and the rotational speed signal is not output for a predetermined period of time counted in block 68, the fuel supply is reduced or cut off. This predetermined time may be an absolute time or may be predetermined according to the period of a predetermined rotational speed,
It can also be determined, for example, by detecting the start of injection.

In the case of the embodiment of the safety device described above, if a sensor important for controlling the internal combustion engine fails, there is no danger to people or property, and emergency driving is possible by detecting an error signal. It can be done.

As explained above, in the present invention, an auxiliary signal is formed from a signal obtained from a sensor other than the rotation speed sensor when the internal combustion engine is in operation, or a starter signal is generated when the starter of the internal combustion engine is operated. Since the emergency driving operation is performed according to the signals from several sensors and the generation results of the auxiliary signal or starter signal, the detection of the auxiliary signal or starter signal that monitors the rotation speed sensor is simply performed when the auxiliary signal or starter signal is generated. It is only necessary to detect whether or not it is occurring, and the circuit configuration can be simplified. In addition, since you only need to check the signal from the rotation speed sensor and the generation results of the auxiliary signal or starter signal, there is no need to compare the magnitude of each individual signal, and the rotation speed sensor can be monitored by a simple means. Corresponding measures such as driving can be taken, and the internal combustion engine can be operated safely.

[Brief explanation of drawings]

Each figure explains an embodiment of the present invention.
The figure is a schematic diagram of the overall configuration of an electronically controlled self-ignition internal combustion engine to which the present invention is applied, and Figure 2 is the configuration and operation of an embodiment in which a rotation speed sensor is checked using a signal from an injection start sensor as an auxiliary signal. FIG. 3 is a flowchart illustrating an example of checking the rotation speed sensor using other signals.
Figure 4 is a diagram showing the output voltage when the output voltage at the start of the generator is used as the check auxiliary signal, and Figure 5 is a diagram showing the relationship between the output signal of other auxiliary signals and the rotation speed. , FIGS. 6a and 6b are flowcharts illustrating operations in different configurations when a start signal is used as an auxiliary signal, and FIG. 7 is a flowchart showing the implementation when checking the rotation speed sensor before each start. FIG. 3 is a flowchart diagram illustrating an example operation. 13...Air amount meter, 15...Supercharging pressure sensor, 1
7... Exhaust gas sensor, 21... Injection valve, 22... Injection start sensor, 24... Starter, 25... Generator, 2
6...Rotation speed sensor, 29...Combustion chamber sensor.

Claims (1)

[Claims] 1. In a self-ignition internal combustion engine safety device for monitoring a rotation speed sensor, injection start and fuel supply that occur when the internal combustion engine is operating and that are obtained from a sensor other than the rotation speed sensor. means for forming an auxiliary signal from a signal relating to quantity, air quantity, boost pressure, exhaust gas or supply voltage, and detecting whether a signal from the rotational speed sensor has occurred as well as whether said auxiliary signal has occurred. 1. A safety device for a self-ignition internal combustion engine, comprising: a means for supplying starting fuel, and then performing an emergency running operation according to a signal from a rotation speed sensor and a result of generation of the auxiliary signal. 2. The self-ignition internal combustion engine according to claim 1, wherein a combination of signals related to injection start, fuel supply amount, air amount, boost pressure, exhaust gas, and power supply voltage is used as an auxiliary signal. safety equipment. 3. Claims 1 or 2, characterized in that the emergency driving operation is performed when there is a signal from the rotation speed sensor and there is no auxiliary signal, or when there is no signal from the rotation speed sensor and there is an auxiliary signal. Safety devices for self-igniting internal combustion engines as described in . 4. The safety device for a self-ignition internal combustion engine according to any one of claims 1 to 3, characterized in that the amount of fuel supplied during emergency running is reduced. 5 If the signal from the rotation speed sensor disappears,
The safety device for a self-ignition internal combustion engine according to any one of claims 1 to 4, wherein an emergency driving operation is performed based on a signal indicating the start of injection. 6. A safety device for a self-ignition internal combustion engine for monitoring a rotation speed sensor, which includes a means for generating a starter signal according to an operation of the starter of the internal combustion engine, and whether or not a signal from the rotation speed sensor is generated and whether the starter 1. A safety device for a self-ignition internal combustion engine, comprising means for detecting whether or not a signal is generated, and performing an emergency running operation according to a signal from a rotation speed sensor and a result of generation of the starter signal. 7. The safety device for a self-ignition internal combustion engine according to claim 6, wherein the starter signal is generated after a predetermined time has elapsed after the starter is operated.