JPS58142258A - Detecting circuit for abnormality of rotating speed detecting signal - Google Patents

Abstract

PURPOSE:To prevent non-control running of an engine, by a method wherein, from a start signal and a rotating speed detecting signal, a trouble due to disconnection of a rotation detector is found early. CONSTITUTION:If the number of revolutions at a starting time exceeds a first rotating speed, in case a detection is normally made, a decision output C1 of a comparator 21 attains a 1, a D type flip-flop 5 is set, and an output alpha attains a 1. If the number of revolutions exceeds a second rotating speed N2, a decision output C2 of a comparator 22 attains a 0, a signal alpha returns to a 0 signal. Meanwhile, in case a rotation detecting signal does not reach due to disconnection, even if a start signal attains a 1 followed by starting of a rotation, the decision output of the comparator 21 does not attain a 1, an AND condition is not established, and thereby the signal alpha remains as it is a 0. It can be regarded as a trouble on detection of rotation that the signal alpha is prevented from attaining a 1. If a rotation detecting speed signal does not reach owing to disconnection under a condition that an engine is running and the number of revolutions is below a first rotation speed N1, a first trouble detecting signal alpha remains as it is a 0, but a second trouble detecting signal beta attains a 0, which results in enabling to detect a trouble on speed detection.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for detecting an abnormality in a rotational speed detection signal of an internal combustion engine, and more particularly, a circuit for detecting an abnormality in a rotational speed detection signal used when an internal combustion engine is electronically controlled. Regarding.

When an internal combustion engine is electronically controlled by feeding back the rotational speed, the engine's rotational speed information plays an extremely important role in power control, and if this information is incorrect, not only will the stable operation of the engine be hindered, but the This may lead to serious accidents such as engine runaway. With the recent development of electronic control systems, it has become necessary to detect abnormalities in the rotational speed signal of an internal combustion engine more quickly than ever before.

Conventionally, the rotational speed of an internal combustion engine has generally been detected using a pickup coil or the like that utilizes an electromagnetic effect on a detection body (for example, a gear) attached to a rotary drive shaft.

On the other hand, on the electronic control unit side that receives such rotation speed detection signals, when the rotation speed is detected as zero, it is difficult to determine whether the cause is because the engine is stopped or whether the engine is being picked up. It is not possible to determine whether the failure was caused by the force of breaking the coil. Therefore, for example, if the engine is started with the pickup disconnected, there is a problem that the control unit operates in a direction that causes the engine to run out of control. In particular, in diesel engines that have a function to increase the amount of fuel supplied to the engine from when the engine key switch is turned on to when the starter is turned on until the engine fully explodes, in order to improve cold starting, the engine can be started with just a key operation. There is a problem with increasing the engine speed to start the engine, as it may cause the engine to reach a dangerous speed or higher.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a circuit that can quickly detect an abnormality in the rotation speed detection signal due to disconnection of the rotation detector, etc. from the engine key switch start signal and the engine rotation speed detection signal. The goal is to provide the following.

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows engine rotation speed N. and its output voltage vN characteristics, FIG. 2 shows one implementation circuit of the present invention, and FIG.
The operating waveforms of each part of the circuit shown in the figure are shown. In the figure,
v3 is the power supply voltage of a battery, etc., and ST, SW
The switch is linked to the key switch and is used to signal the start of the engine. In addition, the output voltage face related to engine rotational speed information can be obtained by, for example, detecting the engine rotational speed using a pickup coil on a gear-shaped detector attached to the engine's drive shaft, and transmitting this detection signal to an appropriate processing circuit, such as a waveform. This is an analog signal obtained through a shaping circuit → mono multivibrator circuit → rectifier circuit (none of which are shown). The input circuit 1 has a filter function and a voltage limiting function, and when the start switches ST and SW are turned on, that is, when the power supply voltage VB is input into the circuit, a start signal is generated that allows subsequent circuits to operate normally. Generates ST. The comparator 21 has two input voltages, that is, an output voltage VH corresponding to the rotation speed.
and the first reference voltage (2), and outputs a judgment output C1 digitally. Similarly, the comparator 22 compares the output voltage VN with the second reference voltage ■, and outputs a judgment output C2.
・Outputs. Here, the voltage is set to V, )V, as shown in FIG.

The first reference voltage V, is the first rotational speed N1. The second reference voltage v2 is set to a second rotation speed FiN higher than the first rotation speed.
*Compatible with. Therefore, when the rotational speed is higher than the first rotational speed N, the judgment output C6 of the comparator 21 is
The determination signal C2 of the comparator 22 becomes a "1" signal when the second rotational speed N is lower.AN
Since the D circuit 3 receives the judgment outputs C1 and 02 as inputs, this output becomes a 1'' signal when the rotational speed is between the first rotational speed N and the second rotational speed N2. Since the output of the AND circuit 3 and the start signal ST are input, this output becomes a 1'' signal only when the rotational speed is between N and N and the start switches ST and SW are on. When the output of the AND circuit 4 becomes 1'', the D-type flip-flop circuit 5 is set to make its output Q (first abnormality detection signal α) 1''.

Since the clock input of the D-type flip-flop circuit 5 operates at the rising edge of the waveform, a NOT circuit 6 is provided between this input terminal C and the output C1 of the comparator 22 described above. Further, an 'O' signal is supplied to the data terminal of the D type flip-flop circuit 5.

Therefore, the output Q of the D-type flip-flop circuit, that is, the first abnormality detection signal α becomes 1'' when the set signal arrives, and becomes a 0'' signal when the rotational speed becomes greater than N2 and the clock input rises.

The second abnormality detection signal β for the rotation speed is the rotation speed N,
This is the output of the OR circuit 7 which receives the judgment output C1 of the comparator 21 operating at It is wired so that when a low speed is detected, the signal is multiplied by NOII.

In the circuit configured as described above, the circuit operation at the time of starting will be explained. When the start switch is turned on and the starting element (for example, a starting motor) of the internal combustion engine (not shown) operates, and the engine rotational speed exceeds the first rotational speed, if the rotational speed is being detected normally. In the upstream shown in FIG. 3, the judgment output C1 of the comparator 21 becomes 1'', the D-type flip-flop 5 is set, and its output α becomes 1''.

When the engine speed further increases and exceeds the second rotation speed N2, the judgment output C2 of the comparator 22 becomes 0'',
The signal α operates to return to the initial state, that is, the "0" signal. On the other hand, if the rotation detection signal does not come due to a break in the signal line, etc., the judgment output of the comparator 21 will not become 1" even if the starting motor starts and the engine starts rotating following the start signal of 1". Since the AND condition in the AND circuit 4 is not satisfied, the signal α, which is the output of the D-type flip-flop 5, remains at 0.Since the signal α operates as described above, the signal α does not become 1. This can be considered as an abnormality in rotation detection. Furthermore, since this signal α returns to the initial state at the second rotational speed N2, FiN during the startup increase period together with the rotational speed abnormality detection signal at the time of startup.
It can also be effectively used as an ABLE signal.

1 Here, the values of the first rotational speed N1 and the second rotational speed N2 will be explained. The rotational speed N is suitably a value that is lower than the maximum rotational speed No obtained from the starting motor and that allows stable detection of the engine rotational speed, for example, 1100RP.

In addition, the second rotational speed is set to a value such that the engine can completely explode and the idle link can be continued smoothly, for example, 1000 to 20.
00RPMKf is good.Next, the circuit operation during normal operation will be explained. When the engine is running at a certain rotation speed and the rotation detection speed signal is lost due to a wire breakage or the like and becomes smaller than the first rotation speed N1, the first abnormality detection signal α remains 0'', but the third As shown by the broken line in the figure, the second abnormality detection signal β becomes '0', and an abnormality in speed detection can be detected. Since this abnormality detection signal β is an OR signal of the start signal ST and the judgment signal C1 of the comparator 21,
is 1'') becomes '1''. That is, the second abnormality detection signal β becomes a signal that indicates an abnormality in rotational speed detection during operation after starting.

According to the present invention, the rotation speed detection signal (output voltage vN in the embodiment) corresponding to the rotation speed of the internal combustion engine, the first reference signal associated with the first rotation speed N1, and the rotation speed N , a second reference signal associated with a higher second rotational speed N, a first discrimination circuit (comparator 21 ) and a second discrimination circuit (AND circuit 3) that identifies the rotational speed range N, ~N2, and when starting the internal combustion engine, the second discrimination signal and the internal combustion engine start signal (
ST ), a first logic circuit (AN
D circuit 4. D flip-flop 5) and a second logic circuit that considers the rotation speed detection signal to be abnormal when the first discrimination signal indicates that it is lower than the first rotation speed N1 based on the first discrimination signal and the start signal. An abnormality detection circuit for a rotational speed detection signal is provided. By using the output α'''0'' of the first logic circuit as an abnormality detection signal at the time of starting, it is possible to cut the fuel and prevent the engine from running out of control even in a one-touch start type internal combustion engine that requires only key operation. . Also, even during normal operation, the start signal (E
By using T) in combination, it is possible to easily identify an abnormality in the rotational speed signal using the second abnormality detection signal β without contradicting the above-mentioned ENABLE signal.

The present invention can be applied not only to the above-mentioned speed feedback/electronic speed control device for an internal combustion engine but also to a feedback control device using an electric motor.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram of the rotational speed of the internal combustion engine and its output voltage.
FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention, and FIG. 3 is an operational waveform diagram of each part of the circuit shown in FIG. VN... Detection voltage corresponding to the rotation speed ■,, v2... First and second reference voltage 21.22: Comparator 5... D type flip-flop α... Abnormality detection signal for starting β ... Abnormality detection signal for use other than when starting Patent applicant: Fuji Electric Kyozo Co., Ltd. Fuji Electric Research Institute Co., Ltd. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1) A rotational speed detection signal that corresponds to the rotational speed of the internal combustion engine, a first reference signal that corresponds to the first rotational speed N, and the first rotational speed. N. a first discrimination circuit that generates a first discrimination signal for discriminating that the rotation speed is higher than N based on a second reference signal associated with a higher second rotation speed N2, and a rotation speed region; a second discrimination circuit that outputs a second discrimination signal for discriminating between N and N2;
a first logic circuit that determines that the rotational speed detection signal is abnormal when the AND condition of both signals is not satisfied; and a second logic circuit that considers the rotation speed detection signal to be abnormal when the first discrimination signal indicates that the rotation speed is lower than the first rotation speed N. 2. In claim 1, the first logic circuit performs an AND operation of the second discrimination signal and the start signal.
An anomaly detection circuit comprising: an AND circuit that takes: and a flip 70 that is set by the output of the AND circuit and clocked when the rotation detection signal reaches the second rotation speed. 3) In claim 1 or 2, the first rotational speed N1 is a rotational speed N obtained from a starting element of an internal combustion engine. An abnormality detection circuit characterized in that the value is set to a value lower than . 4) In any one of claims 1 to 3, the second rotational speed is set to a value that allows smooth idle linkage following the detonation of the internal combustion engine. Anomaly detection circuit.