JPH0629478Y2 - Alarm lamp drive circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an alarm lamp drive circuit device, and more particularly to an alarm lamp drive circuit for reducing malfunctions due to noise components in an alarm device for notifying an abnormal engine occurrence. It relates to the device.

[Conventional technology]

Various detection circuits are used to operate the engine in a normal state, and when an abnormality occurs, the abnormal portion is immediately displayed by an alarm lamp.

Conventionally, as an alarm lamp drive circuit device for an emergency relay that stops the engine when an abnormality such as hydraulic pressure or water temperature is detected, a circuit using a thyristor 6 is used as shown in FIG.

The operation of FIG. 3 will be described. When an abnormality occurs in an engine (not shown), the contact of the detection relay 1 is closed by, for example, a sensor (not shown) that detects the abnormal state, and the input terminal 2 is closed. After that, the detection signal is input to the noise filter unit 3. After the noise component is removed by the noise filter unit 3, this detection signal is input to the comparator unit 4, compared with a predetermined reference voltage by the comparator unit 4 and output as an H level signal. This H-level signal causes the thyristor 6 to ignite through the noise filter section 5, and the ignition of the thyristor 6 causes the alarm lamp 8 connected to the output terminal 7 to be turned on. The H-level signal output from the comparator unit 4 is appropriately amplified by the amplifier unit 9. The amplified H-level signal energizes the relay 10, and the battery voltage is output via the closed contact of the relay 10 to the output terminal. It is supplied to a stop solenoid 12 connected to 11. Therefore, when the alarm lamp 8 is turned on, the engine is guided in the stopping direction.

[Problems to be solved by the device]

In the conventional circuit configuration in which the alarm lamp 8 is turned on by using the thyristor 6, the thyristor 6 is vulnerable to noise and is easily affected by the noise generated from the engine, and the alarm lamp is activated even if the engine maintains a normal state. 8 may illuminate. Therefore, as shown by 3 and 5, it is necessary to attach noise filters in double or triple to remove noise components. However, there is a drawback in that they may not match.

Further, since the thyristor 6 is used, a reset switch for turning off the alarm lamp 8 must be provided in the lamp signal line, which has a drawback that the degree of freedom in mounting the switch is small.

The present invention aims to solve the above drawbacks,
By using a circuit configuration that uses a 3-state buffer with a relatively high noise margin, the alarm lamp is less likely to be erroneously lit and the output is placed in a high-level state. It is an object of the present invention to provide an alarm lamp drive circuit device that can be easily reset simply by giving a signal.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the alarm lamp drive circuit device of the present invention detects the occurrence of engine abnormality with a sensor, removes noise components in the noise filter section, and then lights the alarm lamp based on the detected abnormality signal. In the alarm lamp drive circuit device for notifying the occurrence of engine abnormality, a three-state type for discriminating the engine abnormality signal and the noise component detected by the sensor at the next stage of the noise filter section
A buffer is provided, a diode is connected from the output stage to the input stage of the 3-state buffer, and the 3-state buffer placed in the high level state with respect to the control input terminal of the 3-state buffer. A reset signal for resetting the buffer is provided, and a transistor for lighting the alarm lamp according to an abnormal signal output from the three-state buffer is provided, and the reset lamp is configured to light the alarm lamp. Is configured to reset the high level state of the 3-state buffer. Hereinafter, description will be given with reference to the drawings.

〔Example〕

FIG. 1 shows the configuration of an embodiment of an alarm lamp drive circuit device according to the present invention, and FIG. 2 shows an embodiment circuit diagram of a partial specific example of a general-purpose engine controller in which the present invention is used.

In FIG. 1, reference numerals 1 to 3, 7, 8, 11, 12
3 corresponds to that of FIG. 3, reference numeral 13 is a 3-state buffer, 14 is a transistor, 15 is a stop solenoid drive circuit, 16 to 18 are diodes, and 19 to 21 are resistors.

The alarm lamp 8 is turned on by the transistor 14, and the transistor 14 is turned on by three states.
It is controlled by the output signal of the buffer 13. The noise intensity of the 3-state buffer 13 is equivalent to that of the logic IC, and when the power supply voltage (Vcc) is 5 V, for example, it outputs an H level signal for an input signal of 2.5 V or more. Therefore, the 3-state buffer 13 holds the L level for a noise component of 2.5 V or less, and has a high noise margin and also has a filter effect of removing the noise component. Therefore, the filter of the noise filter unit 3 can be a normal noise filter circuit that removes sharp high-voltage noise, and it is sufficient to dispose one filter immediately before the 3-state buffer 13 concerned.

When an abnormal state occurs in the engine, an H level signal indicating an abnormal signal is output from the three-state buffer 13, and the diode 16 outputs from the output of the three-state buffer 13 as will be described later based on the specific example shown in FIG. On the basis of this, the 3-state buffer 13 is connected to the input and is placed in the set state. At the same time, the transistor 14 is turned on, and the alarm lamp 8 connected to the output terminal 7 is turned on. At the same time, the H-level signal of the 3-state buffer 13 is input to the stop solenoid drive circuit 15 via the diode 17 and is connected to the output terminal 11 of the stop solenoid 12.
Energize to stop the engine.

The lit alarm lamp 8 is turned off by applying the L level reset signal to the reset input of the 3-state buffer 13 so that the H-level signal of the 3-state buffer 13 changes to the L level. At this time, the stop solenoid 12 is also deenergized.

FIG. 2 is a circuit diagram of an embodiment of a general-purpose engine controller in which the present invention is used, and shows an example in which there are two engine abnormality detections.

In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals, and reference numerals 17-1 and 17-2 are diodes and 18 '.
Is an inverter circuit, 19 'is an input inversion NAND circuit, 2
Reference numeral 0'denotes a diode, 21 'a resistor, 22 a noise filter section, 23 a reset switch, and 24 an input terminal. A diode 16 connected from the output of the three-state buffer 13 toward the input and a pull-up resistor 2 included in the noise filter unit 3 shown in the figure are included.
With the three resistors, the 3-state buffer 13 once placed in the high level state holds the set state.

For example, when the oil pressure of the engine drops for some reason, the abnormality occurrence is detected by a sensor (not shown), the contact of the detection relay 1 indicating the occurrence of the oil pressure abnormality is opened, and the abnormality signal appears at the input terminal 2. 3 states
The output of the buffer 13 becomes H level, and the transistor 1
Warning lamp 8 that turns on 4 to notify the occurrence of hydraulic pressure abnormality
Lights up, and stops via diode 17-1.
The solenoid drive circuit 15 is activated, the stop solenoid 12 is energized, and the engine is stopped.

The alarm lamp 8 is turned off by the generation of a reset signal that lowers the output of the inverter circuit 18 'by closing the reset switch 23.

The engine water temperature detection operates in exactly the same way.

A large number of three-state buffers 13 are mounted on one IC, and an input inversion NAND circuit 19 'is also mounted on the circuit board of the abnormality detection system that detects the abnormality of the engine using a large number of sensors. The implementation in is very convenient.

[Effect of device]

As described above, according to the present invention, since the three-state buffer is used, it is resistant to noise, and the alarm lamp lights up and the stop solenoid operates simultaneously, and the alarm lamp lights up and the engine stops. And will match, eliminating malfunction.

The number of noise filter sections for noise removal can be reduced, and a normal noise filter circuit can be used.

Moreover, since the alarm lamp can be turned off by lowering the reset switch to the L level, the degree of freedom in mounting the alarm lamp is increased.

Since an IC having a plurality of three-state buffers mounted thereon can be used, the mounting area on the board can be small and the board can be miniaturized.

[Brief description of drawings]

1 is a circuit diagram of an embodiment of an alarm lamp driving circuit device according to the present invention, FIG. 2 is a circuit diagram of an embodiment of a partial portion of a general-purpose engine controller in which the present invention is used, and FIG.
The figure shows a conventional circuit configuration diagram. In the figure, 3 is a noise filter section, 13 is a 3-state buffer, 8 is an alarm lamp, 12 is a stop solenoid,
Reference numeral 14 is a transistor, and 15 is a stop solenoid drive circuit.

Claims (1)

[Scope of utility model registration request] 1. An alarm lamp drive for detecting an engine abnormality occurrence by a sensor, turning on an alarm lamp based on the abnormality signal detected after the noise component is removed by a noise filter section, and notifying an engine abnormality occurrence. In the circuit device, in the next stage of the noise filter section, a three-state circuit for discriminating an engine abnormal signal detected by a sensor from a noise component
A buffer is provided, a diode is connected from the output stage to the input stage of the 3-state buffer, and the 3-state buffer placed in the high level state with respect to the control input terminal of the 3-state buffer. A reset signal for resetting the buffer is provided, and a transistor for lighting the alarm lamp according to an abnormal signal output from the three-state buffer is provided, and the reset lamp is configured to light the alarm lamp. The alarm lamp drive circuit device is configured to reset the high level state of the three-state buffer according to the above.