JPS6157450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a warning device that detects a decrease in the amount of oil in an oil pan of an internal combustion engine such as a wheel and issues an alarm, and which is configured to hold a detection signal.

As an oil level warning device for internal combustion engines, the thermistor is installed at the required minimum oil level in the oil pan, and its resistance changes due to self-heating temperature changes that occur depending on whether it is submerged in oil or exposed in the air. Use this to make the operational amplifier sense changes in potential,
Accordingly, a system has been proposed in which a signal emitted from an operational amplifier is inputted to the base of a transistor in an alarm circuit including a warning light or buzzer to activate the warning light or buzzer. For example, the above-mentioned thermistor devised by the present applicant is attached to a conventional oil level gauge (Utility Application No. 129326/1982).

Originally, the amount of oil in the oil pan fluctuates and is not constant during engine operation, so it is desirable to detect it when the engine has stopped and the oil level has stabilized. However, with a thermistor, resistance changes due to self-heating are stable. Since it takes time for the detection to occur, there is a delay in detection. Therefore, there is a problem in that detecting the amount of oil requires some waiting time immediately after the engine is stopped or while the engine is stopped, and when starting the engine, it is necessary to wait for that amount of time.

This invention was made in order to solve the above problem, and it continues to send a signal to the alarm circuit even after the set time of the timer unit has elapsed, and when the ignition switch is turned on to start the engine next time, the signal is sent. The alarm circuit that was receiving the oil was connected to a power source and issued an alarm based on the detection signal when the oil level was stable.

To explain this invention by way of an embodiment, in FIG. 1 showing a circuit of an apparatus according to one embodiment, a power supply 1 passes through a timer unit 3 provided with a push button switch 2 to form the following circuit. That is, (1) power supply 1 - timer unit 3 - resistor 4 - transistor 5 (emitter-collector) - resistor 6 - ground.

(2) Timer unit 3-resistor 7-transistor 8
(Emitter collector) - Thermistor 9 - Ground.

(3) Timer unit 3 - Resistor 10 - Resistor 11 -
ground.

(4) Timer unit 3 - operational amplifier 12 (operating power supply terminal) - ground.

(5) Timer unit 3 - Diode 13 - Warning light or buzzer 14 - Transistor 15 (collector-emitter) - Ground.

In addition to the above, (6) Power supply 1 - Reset switch 16 - Resistor 17 -
Thyristor 18 (anode-cathode) - gate of transistor 15.

(7) Power supply 1 - ignition switch 19 - diode 20 - warning light or buzzer 14.

(8.1) Base of transistor 5 - base of transistor 8.

(8.2) Intermediate connecting the bases of transistors 5 and 8 - collector terminal of transistor 5.

(9.1) Collector terminal of transistor 8 - negative terminal of operational amplifier 12.

(9・2) Intermediate operational amplifier 1 with resistors 10 and 11
2 positive terminal.

(10・1) Output signal terminal of operational amplifier - resistance -
Resistor - 22 - Base of transistor 15.

(10・2) Base of transistor 15 - Resistor 2
3- Grounding.

(10・3) Intermediate between resistors 21 and 22 - gate of thyristor 18.

The circuit as described above is configured.

In the circuit, the pushbutton switch 2, timer unit 3, reset switch 16, and warning light or buzzer 14 are provided in the driver's cab. The thermistor 9 is attached to an oil level inspection rod or fixed to the inner wall of the oil pan so as to be located at the lowest oil level in the oil pan. The resistor 7, thermistor 9, and resistor holes 10 and 11 constitute a bridge, and when the thermistor 9 is in oil, the operational amplifier 12
The negative terminal of the operational amplifier 12 is set to be more positive than the positive terminal, and when the thermistor 9 is in the air, the negative terminal of the operational amplifier 12 is set to be more negative than the positive terminal. diode 1
3 and 20 are for reverse current prevention, and resistors 4, 6, and 1
7, 21, 22, and 23 are for current limiting of related elements.

Since the device according to the present invention has the above-described circuit, it operates as follows. When the push button switch 2 is pressed, the timer unit 3 is activated to conduct the current from the power source 1 for the set time. The time set by the timer unit 3 is set to be longer than the time required for the oil level to stabilize after engine operation is stopped and the detection delay time of the thermistor.

The relationship I _E =V _Z −V _EB /R _I holds between the base input voltage V _z of transistors 5 and 8 and the emitter voltage I _E of transistor 8, and I _E
Since it is considered as ≒I _C , a constant voltage can be applied to the thermistor 9. Transistor 5 is transistor 8
It is inserted to compensate for the temperature coefficient of _VEB .

As mentioned above, resistor 7, thermistor 9 and resistor 1
0 and 11 constitute a bridge, and each resistance value is set so that when the thermistor 9 is in oil, the voltage at the negative terminal of the operational amplifier 12 is more positive than the voltage at the positive terminal, so the operational amplifier There is no signal output from 12. When the thermistor 9 is exposed to the air, the temperature increases due to self-heating and the resistance decreases, so that the voltage at the negative terminal of the operational amplifier 12 becomes more negative than the voltage at the positive terminal, and the signal output from the operational amplifier 12 reaches the base of the transistor 15. Thus transistor 1
5 is activated, the current from the timer unit 3 through the diode 13 and reaching the warning light or buzzer 14 is grounded and an alarm is issued. At the same time, the signal output of the operational amplifier 12 reaches the gate of the thyristor 18, so that the current from the power supply 1 through the reset switch 16 passes through the thyristor 18 and reaches the base of the transistor 15. When a certain period of time set in the timer unit 3 has elapsed, the transistors 5,
8. The power to the operational amplifier 12 and the warning light or buzzer 14 is cut off, and the alarm stops. In this case, even if the signal to the gate of the thyristor 18 is cut off, the signal continues to be sent to the base of the transistor 15 in the alarm circuit because it is connected to the power supply 1 via the normally closed reset switch 16. There is.

The above action remains the same whether the engine is running or stopped. However, in order to accurately detect it, it is necessary to operate it while the operation is stopped, but with conventional devices, you have to wait for the resistance change of the thermistor to stabilize, and immediately after the operation is stopped, you have to wait until the oil level stabilizes.
The start of engine operation must be delayed accordingly.

However, in the warning device according to this invention,
Even after the set time of the timer unit has elapsed, a weak signal current is sent to the gate of the transistor 15 by the action of the thyristor 18, so if the push button switch 2 is pressed while the engine is stopped, the alarm circuit is activated immediately via the diode 13. Closed and raises alarm. In order to start driving again, I turned on the ignition switch 1.
When 9 is turned on, the current of power supply 1 is diode 20
The transistor 1 reaches the warning light or buzzer 14 through
5, it will touch the ground and issue an alarm. After confirming the alarm, operate the reset switch 16 to reset the thyristor 1.
8 is restored and stops operating when the power is cut off.

According to the warning device of this invention, by operating the push button 2 when the operation is stopped, it is possible to receive a warning when the oil level is stable while the operation is stopped or at the next start of operation, and when the engine is started and when the engine is stopped. The driver is not forced to be tied up in the driver's cab for a considerable amount of time to check the oil level. Furthermore, this device is extremely compact and can be easily attached to existing vehicles by attaching and connecting the thermistor to an existing oil level gauge.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a circuit in an embodiment of the device of the present invention. Timer unit...3, Transistor...5,
8, 15, thermistor...9, operational amplifier...1
2. Thyristor...18.Warning light or buzzer...1
4.

Claims (1)

[Claims] 1. A circuit that applies current to the device for a certain period of time using a timer unit and detects a change in resistance during self-heating that occurs depending on whether the thermistor placed in the oil pan is in the air or in the oil; and the circuit. A circuit that maintains the signal given to the alarm circuit even after a certain period of time set in the timer unit has elapsed in an oil level warning device for an internal combustion engine, which is equipped with an alarm circuit that amplifies the signal issued by the engine and activates the alarm. An oil amount warning device for an internal combustion engine, characterized in that the alarm circuit is connected not only to the timer unit but also to an ignition switch of the engine.