JPH0236884Y2 - - Google Patents

Description

[Detailed Description of the Invention] Field of Industrial Application This invention relates to an engine oil reduction warning device that detects the oil level after the engine is stopped and issues a warning when the oil level is below a predetermined value.

〓Summary of the invention〓 An oil level detection circuit that measures the resistance value of a thermistor installed at a predetermined level position in the engine and detects when the engine oil has decreased below the predetermined level position, and an oil level detection circuit that measures the resistance value of a thermistor installed at a predetermined level position in the engine and detects when the engine oil has decreased from the predetermined level position, and a predetermined time period after starting a timer by operating a switch. a timer that operates an oil level detection circuit when the oil level detection circuit has elapsed, and a reset circuit that maintains the timer in a reset state when the ignition switch is closed, and starts energizing the thermistor at the same time as the timer is started. This is an engine oil low warning device that reduces the time required to detect the oil level.

〓Prior art〓 The present applicant has developed an engine that detects a change in the resistance value of a thermistor due to the difference in temperature rise between oil and air to notify that the engine oil level has fallen below a specified level. We have developed an oil reduction detection device and have already filed a utility model registration application and published it. (Original Application No. 59-44949, Actual Publication No. 1-38251
Figure 2 shows the oil level detection circuit.
If you press SW1 to start the device, the engine oil will fall into the oil pan, and after a predetermined period of time it will detect whether or not there is a specified amount of engine oil, and if there is insufficient oil, it will turn on the light emitting diode. The result is memorized and the same lighting display is performed the next time the engine is started.

To briefly explain its circuit configuration and operation, the oil level detection circuit consists of two timers.
IC1 and IC2, switching transistor T1 controlled on/off by timer IC2, thermistor N installed at a predetermined level position in the oil pan, comparison circuit IC3 that compares the terminal voltage of thermistor N with a reference voltage, and output of comparison circuit IC3. Thyristor Th that holds the , light emitting diode D1 that indicates oil shortage and disconnection of thermistor N, light emitting diode D2 that displays operation, relay for self-holding.
It consists of a reset relay RL1, a reset relay RL2, etc. that keeps the timer in a reset state when the ignition switch SW3 is closed.

Of the two timers IC1 and IC2, the former has a longer operating time (for example, IC
1 for 10 minutes, IC2 for 5 minutes) After the engine stops, press push switch SW1 to start both, H level voltage is output to terminal 3 of both, and self-holding relay RL1 operates to hold the power supply circuit self-holding. However, when the operation of timer IC2 ends after a predetermined period of time (around the time when the engine oil falls into the oil pan), the output of its No. 3 terminal becomes L level, transistor T1 becomes conductive, and resistor R1 and thermistor N
A power supply is connected to the series circuit and comparison circuit IC3.

When the engine oil is less than the specified amount, an H level signal is output to the output terminal of the comparison circuit IC3.
Transistor T2 conducts and light emitting diode D1
lights up to indicate lack of oil.

At the same time, the thyristor Th is turned on, and even after the operation of the timer IC1 ends and the self-holding relay RL1 is cut off (because current is supplied through the reset switch SW2), the thyristor Th remains on. When the ignition switch SW3 is closed the next time the engine is started, the transistor T2 becomes conductive and the light emitting diode D1 lights up to indicate the oil shortage.

However, in such a device, since the current flowing through the thermistor N is small, its self-heating rate is slow, so unlike conventional devices, push switch SW1 is pressed and energization to the thermistor N is started after a predetermined time. However, there was a drawback in that it took quite a long time after the push switch SW1 was pressed until the thermistor N reached a steady temperature and an oil shortage was detected.

〓Problems to be solved by the invention〓 The purpose of this invention is to improve the above-mentioned drawbacks of the conventional device, and to create an engine oil low warning device that shortens the time required for detecting oil shortage after starting the timer. It is to provide.

〓Means for solving the problem〓 In order to achieve the above object, the engine oil low warning device of this invention measures the resistance value of a thermistor installed at a predetermined level position in the engine, and measures the resistance value of a thermistor installed at a predetermined level position in the engine. An oil level detection circuit that detects that the oil level has decreased below the level position, a timer that operates the oil level detection circuit when a predetermined time has elapsed after the timer is started by switch operation, and a timer that resets the timer when the ignition switch is closed. and a reset circuit to keep the timer constant, so as to start energizing the thermistor at the same time as starting the timer.

〓Effect〓 Since the thermistor is energized for a predetermined period of time after the timer starts and its temperature rises due to self-heating, the oil level cannot be detected immediately or within a short period of time after the timer starts. It can be done.

〓Example〓 An example of this invention will be described with reference to FIG.

The difference from the conventional device described above is that the thermistor N and the comparison circuit IC3 are directly connected to the push switch SW1 (without going through the switching transistor T1), and the device emits light via the switching transistor T1 and diode D3 during level detection. The difference is that power is supplied to the diode D1, and other points are completely the same.

The thermistor N is attached to the tip of the oil level gauge, and is placed at a predetermined level position when the oil level gauge is inserted into the oil pan.

Thermistor N is energized at the same time as timers IC1 and IC2 start, and its temperature rises due to self-heating, and after a predetermined period of time (engine oil falls into the oil pan), it reaches a nearly steady temperature when timer IC2 stops operating. It's becoming like that.

Next, the operation will be explained in the case of oil shortage.

When the push switch SW1 is pressed after the engine has stopped, timers IC1 and IC2 are activated and current is supplied to the thermistor N. After a predetermined period of time, the operation of the timer IC2 ends and the light emitting diode D1 is activated.
When the power is connected to the thermistor N, if the thermistor N has already reached a steady temperature, the light emitting diode D1 will immediately light up to indicate the oil shortage, and
Even if the thermistor N has not reached the steady temperature, it will reach the steady temperature in a short time and the light emitting diode D will
1 lights up.

In the above embodiment, the timers IC1 and IC2 are started by manually pressing the push switch SW1 after the engine has stopped, but this is not a limitation. Needless to say, the timer may be started automatically when

Effects of the invention As explained above, the engine oil low warning device of this invention measures the resistance value of the thermistor installed at a predetermined level position in the engine and detects when the engine oil has decreased below the predetermined level position. A timer that operates the oil level detection circuit when a predetermined time has elapsed after the timer is started by a switch operation, and a reset circuit that maintains the timer in a reset state when the ignition switch is closed. , by starting energizing the thermistor at the same time as starting the timer,
If you start the engine during oil level detection, the oil level detection circuit will stop, and if you perform detection while the engine is running, the oil level detection circuit will not operate, so there is no risk of malfunction. Wasteful power consumption can be prevented, and since the oil level is detected immediately or within a short period of time after the timer starts, the oil level can be detected in a shorter time than with conventional devices. It is something that can be done.

[Brief explanation of drawings]

FIG. 1: A circuit diagram of an embodiment of this invention; FIG. 2: A circuit diagram of a conventional device. D1...Light emitting diode, D3...Diode, IC1...Long operating time timer, IC2...
...timer with short operating time, IC3...comparison circuit,
N...Thermistor, T1...Switching transistor.

Claims (1)

[Claims for Utility Model Registration] (a) An oil level detection circuit that measures the resistance value of a thermistor installed at a predetermined level position in the engine and detects that the engine oil has decreased below the predetermined level position; ) a timer that operates an oil level detection circuit when a predetermined period of time has elapsed after the timer was started by a switch operation; (c) a reset circuit that maintains the timer in a reset state when the ignition switch is closed; (d) An engine oil reduction warning device characterized in that energization of the thermistor is started at the same time as the timer is started.