JPS58204909A - Method and circuit for detecting engine lubircating oil - Google Patents

Abstract

PURPOSE:To detect the shortage of engine lubricating oil from the change in the resistance of a thermistor, by providing the thermistor so that it is in contact with the engine lubricating oil sprinkled in a crankcase due to engine running. CONSTITUTION:When the amount of engine lubricating oil in a crankcase has become lower than a prescribed level, enough lubricating oil is not sprinkled in the crankcase. As a result, a first thermistor Th1 comes out of contact with enough lubricating oil so that the temperature of the thermistor rises and its resistance decreases. Then, a first transistor Tr1 is turned off and other transistors Tr2, Tr5, Tr4, Tr3 are also turned off in that order. Charge stored in a capacitor C4 is sent out to an output terminal (e) through the transistor Tr3 to drive an indicator to show that the amount of the engine lubricating oil has dropped below the prescribed level.

Description

[Detailed description of the invention] The present invention does not use an oil pump.

This article relates to a method and a detection circuit for detecting engine oil in a four-stroke engine, which has a structure in which the engine oil stored in the crankcase is scattered by vanes installed on the crankshaft. The purpose of this system is to constantly monitor the amount of engine oil to ensure safe engine operation.

Another purpose is to automatically achieve safe operation by emitting an output signal when the amount of engine oil in the crankcase falls below a specified amount, such as stopping engine drive. be.

For small 4-stroke engines that do not use an oil pump but instead use vanes installed on the crankshaft to disperse the engine housed in the crankcase, checking the amount of engine oil is extremely troublesome. Because it is an easy task to forget, there are cases where the engine continues to run even when the engine oil level is low, causing a serious accident, or even if it does not cause an accident, it may cause the engine to operate in an extremely inefficient state. I often continued.

For this reason, in this type of engine, there has been a strong desire for an engine that can notify the driver when the amount of engine oil falls below a specified amount.

The present invention was devised in response to the above-mentioned conventional demands, and the engine oil stored in the crankcase is scattered by the blades provided on the crankshaft, and the temperature of the engine oil is controlled by the engine. Taking advantage of the fact that the temperature is lower than that of other parts, as the engine oil decreases, the engine oil no longer scatters, and the temperature of the temperature-sensitive resistor that was in contact with the engine oil that used to be scattered changes. This system generates an output signal according to the change in resistance value caused by the change in the resistance value, thereby detecting that the engine oil level has fallen below a specified level.

Embodiments of the present invention will be described below with reference to the drawings.

The method for detecting engine oil according to the present invention is carried out on a four-cycle engine, which has a structure in which engine oil stored in the crankcase is scattered by vanes provided on the crankshaft. A temperature-sensitive resistor Th1 such as a thermistor (hereinafter, a thermostatic resistor will be explained as an example) is provided to make contact with the engine oil in the engine, and the lack of engine oil can be detected by the change in resistance of the thermistor Th1.

In other words, when a sufficient amount of engine oil is stored in the crankcase, a large amount of engine oil is scattered when the engine is driven. The engine is now cooled by this engine oil.

From this state, when the amount of engine oil in the crankcase decreases and the amount of engine oil that is blown away decreases, the thermistor Thl comes into less contact with the engine oil, so the engine oil can no longer cool the thermistor Thl. As it deteriorates, the temperature of the thermistor Thl rises, and the resistance value of the thermistor Thl changes.

Therefore, by knowing the change in the resistance value of this thermistor Thl, it is possible to know the amount of engine oil.

As is well known, the temperature of the engine oil stored in the crankcase changes depending on the engine condition, and therefore the resistance value of the thermistor Thl has nothing to do with the lack of engine oil. It will change without any change.

In the case of the present invention, the operation is not caused by a change in the resistance value of the thermistor Thl due to a change in the engine state described above, but by a temperature change in a state in which the thermistor Thl is in contact with the engine oil and in a state in which it is no longer in contact with the engine oil. Therefore, it is necessary to prevent the operation from occurring due to the temperature change of the thermistor Thl due to the change in the engine condition described above.

This is a means to prevent the thermistor Thl from operating due to a temperature change caused by a change in the state of the engine.

Broadly speaking, in addition to the above-mentioned thermistor Thl that comes into contact with the scattered engine oil, there is also a thermistor Thl that comes into contact with the engine oil at all times.

A means for comparing the resistance values of both thermistors Thl and Th2 and knowing in advance the upper limit temperature of the engine oil when the engine is running, and setting the resistance value of the thermistor Thl to a value corresponding to a temperature higher than the upper limit temperature of the engine oil. There is a way to know and detect what has happened.

A specific detection circuit OAO configured using these two means
An example will be described according to the drawings.

First, an example of a circuit using the fan 10 means will be explained.

Engine oil detection circuit OAO using method 1
The basic structure of Volume 11! Two ignition circuits are connected in parallel between both terminals of the primary winding 11Jrs of the ignition coil T with the plug P connected to T2, and the piston 1 that comes in contact with the engine oil in the case of the crank j′1 that is scattered by the engine drive. Transistor Tri of spear 1, which has a thermistor connected to the base, and transistor Th2 of spear 2, which is in constant contact with the engine oil stored in the crankcase, are connected to the base]・2 transistors Th2 are connected in parallel. A series circuit of a dynamic amplifier circuit and a diode DI of fang 1.

, 1 to 2 are connected to a series circuit of a charging capacitor C3 and a charging capacitor C3, and the transistor Tri is turned off when the thermistor Thl is not in contact with the engine oil.

J12.7) Transistor Tr2 is turned on by turning off transistor Trl,
The transistor Tr3 is provided with a tooth 3 which is turned on when the transistor Tr2 of the spear 2 is turned on and outputs the electric charge charged in the charging capacitor 03 to the output terminal E.

In the case of the embodiment shown in Fig. 1, the detection circuit OAO includes a stabilized power supply AVR connected to a series circuit of the diode DI of Fig. 1 and a differential amplifier circuit composed of both transistors Trl and Tr2.
in series; although a large configuration is shown.

The differential amplifier circuit has a good common mode rejection ratio, so it is resistant to voltage fluctuations.
Therefore, it is not necessary to provide this stabilized power supply AVR.

The thermistor Th1 of the fang 1 is connected in series with the resistor rl to form a voltage dividing circuit, and the base of the transistor Tri of the fang l is connected to the voltage dividing point of this circuit.
Thermistor Th2 also forms a voltage dividing circuit with resistor r4, and the base of transistor Tr2 of fan 2 is connected to the voltage dividing point, and the emitter of transistor Tri and Tr2 are connected to the primary winding TI through resistor r2. K is connected.

The base of the transistor Trl is connected to the collector of the transistor Tr2 of the fang 2, and the resistor r3 as a base resistance of this transistor Trll is connected, so the transistor Tr6 is turned on by turning on the transistor Tr2 of the fang 2. It turns out.

The collector of this transistor Tr5 is connected to the base of a transistor Tr4 via a resistor.

Therefore, when the transistor Tr5 is turned on, the transistor Tr4 is also turned on.

Also, between terminals A and B, which are both terminals of the next winding T1,
A parallel circuit of a diode and a resistor r6 and a series circuit of a charging capacitor C3 and a diode D3 are inserted.
The charging capacitor C3 is charged with the polarity shown in Figure 1.

The positive side electrode of this charging capacitor C3 is.

It is connected to the emitter of the third transistor Tr3 via a diode D4, and the collector of this third transistor Tr3 is connected to the output terminal E via a backflow blocking diode D6.

Since the base of the transistor Tr3 of the spear 3 is connected to the collector of the transistor Tr4 described above through the resistor and the diode D6, the transistor Tr3 of the spear 3
is turned off by turning on the transistor Tr4.

Further, a capacitor 04 is inserted between the emitter of the transistor Tr3 of the fang 3 to which the diode D4 is connected and the anode of the diode D2 of the fang 2, and the charge stored in the charging capacitor 03 is transferred to the capacitor 03→
The battery is charged via the path of diode D4 → capacitor C4 → resistor rs → capacitor C3.

rf #l spear 1 01 in the diagram is a filter capacitor,
02 is provided when a three-terminal regulator is used as the stabilized power supply AVR.

Furthermore, capacitor 05 is a noise filter.

The embodiment shown in Figure 1 has the configuration as described above, so
As long as the thermistor Thj of spear 1 is in contact with the scattered engine oil, the temperature of the thermistor Thl of spear 1 is low and exhibits a high resistance value, so the transistor Trl of the spear 1 is kept turned on, and this transistor Trl is kept turned on. By turning on the transistor Tr1 of the transistor Tr1, the transistor Tr2 of the tooth 2 is kept turned off.

In this state, for some reason, the amount of engine oil in the crankcase decreases to below the specified level (1), and if the engine oil in the crankcase is not sufficiently scattered, the thermistor Thl
is unable to make sufficient contact with the engine oil, which causes its temperature to rise and its resistance to decrease.

When the resistance value of the thermistor Thl of spear J decreases.

, t'l is turned off, and due to the turn-off of the transistor Trl of 1, the transistor Tr2 of 2 is turned off. Transistor Tr5. ) The transistor Tr4 and the transistor Tr3 of the fan 3 are turned on in this order.

On the other hand, a part of the voltage induced in the primary winding TI is .

The charging capacitor C3 is charged, and the charged charge is transferred to the capacitor C4 during the inversion period of the induced voltage in the primary winding TI.

In this state, as mentioned above, the transistor Trl of fang 1
When turns off, the third transistor.

Since Tr3 is turned on, the electric charge charged in this capacitor 04 is outputted to the output terminal E through the transistor Tr3 of this fang 3, and is used as a display device or alarm device to indicate that the amount of engine oil has fallen below the specified amount. drives the example auxiliary circuit.

FIG. 1 shows an example in which the engine stop circuit BeS is driven by the detection circuit OAO.

That is, when transistor Tr3 of fang 3 is turned on, discharging occurs in the path of capacitor C4 → transistor Tr3 → diode D6 → capacitor 06 → capacitor C4, and the capacitor 06 of the stop circuit 18 is charged with the polarity shown in the diagram. .

When the capacitor 06 is charged, the primary winding TI
When the induced voltage of 1 is reversed in the forward direction, the charge charged in the capacitor 06 is discharged to the gate of the silicon-controlled rectifier SOR, and the silicon-controlled rectifier SOR becomes conductive.
Since both terminals of the next winding T1 are short-circuited, the ignition circuit TOI is no longer able to perform the ignition operation, and the engine stops driving.

The actual example shown in Fig. 2 has a simplified circuit configuration by removing the stabilizing power source VR in the embodiment shown in Fig. 1, and eliminates the capacitor 04 and reverses charging capacitor 03. It is configured to directly output the directional voltage to the output terminal E through the transistor Tr3 of the fan 3.

In the embodiment shown in Figure 3, the thermistor Th of the spear 1 and the fang 2 are
l, Th2 and fang l, transistor Tri of fang 2
, Tr2K shows yet another embodiment in which a differential amplifier circuit is formed using 923 transistors Tr2K.
2 shows an example in which a photo coupler combined with a light emitting diode HD is used, and the light emitting diode HD 2 is connected in series to the transistor Tr4.

In the case of the embodiment shown in Fig. 3, the differential amplifier circuit side and the charging capacitor 03, that is, the transistor Tra
Since there is no need for connection to the side, there is an advantage that one circuit configuration can be simplified.

Furthermore, in the embodiment shown in Fig. 4, the thermistor T of fang l
This shows an example of a specific circuit configuration of a means using only hl, in which an oni transistor T is installed at the voltage dividing point of a voltage dividing circuit which is a series circuit of a resistor R and a thermistor Thl of 1.
The circuit connecting the emitter of rl and the diode DI of fang l
A series circuit is inserted between the terminals 499, and a transistor Tr3, which is turned on when the transistor Trl is turned on, is inserted between the output terminal E and one terminal port.

That is, a transistor Th-5 is provided, the base of which is connected to the collector of the transistor Trl via a resistor, and the collector of this transistor Tr5 is connected to the base of the transistor Tr3 of the third transistor via a resistor. It is.

In addition, in the case of the embodiment shown in this spear 4 figure, fang 1 figure or spear 3 figure
In the illustrated embodiment, the charging capacitor 03, which was the acid part of the detection circuit 0AOcl), is not provided exclusively.
The capacitor 06 used in the stop circuit ESB is configured to also have the function of the charging capacitor 03, thereby making the circuit configuration of the detection circuit OAO simpler.

Since the embodiment illustrated in the fang 4 has the above-described configuration, if the engine oil scattered in the crankcase □ is in sufficient contact with the thermistor Thl of the fang l, there will be no problem. Since the resistance value of the transistor Thl is large, the transistor Trl)! Blocked state [Yes, the detection circuit OAO is in an inactive state.

From this state, when the thermistor Thl of the fang l no longer contacts the engine oil, the high @
As a result, the temperature of the thermistor Thl of the fang 1 rises, and finally reaches a temperature higher than the maximum temperature that the engine oil in the crankcase can reach, and the resistance value of the thermistor Th of the fang 1 decreases significantly.

Therefore, if the resistance value of the resistor R is set in accordance with the resistance value of the thermistor Thl of the fang l, which corresponds to a temperature slightly higher than the maximum temperature that the engine oil in the crankcase can reach, the thermistor of the fang l When Thl is no longer in contact with the engine oil and the state described above is reached, the transistor Trl is turned on, and by turning on the transistor Trl, the transistor Tr6 is turned on.
Then, the transistor Tr3 of the fang 3 and the gate is turned on.

When transistor Tr3 of spear 3 is turned on, the primary winding is connected to capacitor 06 via the path of terminal A → resistor r6 of stop circuit gss → diode D8 → capacitor 06 → resistor and diode D1 → transistor Tr3 of spear 3 → terminal port. A portion of the reverse voltage generated by TIKN is charged with the polarity shown, and this charged voltage triggers the silicon-controlled rectifier SOR, thus activating the stop circuit 'gss. .

In the embodiment shown in Fig. 4, by replacing the resistor R with the thermistor Th2 of the spear 2, the resistance of 1.4
The circuit shown in the figure may have a similar operational function as the circuit shown in FIG.

In this way, the present invention detects the amount of engine oil by using the scattering of engine oil in the crankcase due to engine drive, so it is possible to monitor the engine oil while the engine is running. You can drive more safely.

As for the configuration of the engine itself, it is easy to implement it because all you need to do is attach the temperature-sensitive resistor of spear 1 so that it can come into contact with the engine oil scattered in the crankcase.

Furthermore, it is possible to always perform normal functions regardless of changes in the engine position or operating conditions.

As is clear from the above description, the present invention can reliably and accurately detect that the amount of engine oil in the crankcase has fallen below the specified amount while the engine is running, thereby making the engine safer. It is easy and simple to carry out, as it can be carried out simply by providing the temperature sensitive resistor of the fan l so that it can come into contact with the scattered engine oil in the crankcase. Furthermore, the present invention exhibits many excellent effects such as being able to exhibit stable detection ability without being affected by changes in the engine position and operating conditions.

[Brief explanation of the drawing]

The drawings show an electrical circuit illustrating an embodiment of the invention.
Figures 1 to 3 are configured to operate using the difference in resistance between two temperature-sensitive resistors, and Figure 4 is configured to operate based on temperature changes in one temperature-sensitive resistor. It is something. Symbol explanation OAO...detection circuit, Thl, Th, 2...
・Thermistor. 'rrt, Tr2, Tr3, Tr4,
Tr6-) transistor. 0!1, 04... Capacitor, Di, D2... Diode. HD-...Light emitting diode, rl, r2. r3. r4.
r5. R-resistance, ESS...stop circuit. Inventor Hiroyoshi Komiya Applicant Representative Iida Denki T Gyo Co., Ltd. Ii 1) Sawako Grand 19 Goashi 3 layers

Claims (2)

[Claims] (1) A temperature-sensitive resistor such as a thermistor is installed so that it comes into contact with the engine oil in the crankcase that is scattered by the engine, and the change in the resistance value of the temperature-sensitive resistor is used to detect a lack of engine oil. Detection method. (2) Between both terminals of the primary winding of the ignition coil. When the engine comes in contact with the engine oil in the crankcase that is scattered by the engine drive, the transistor connected to the base of the temperature-sensitive resistor of 1 is installed to be in constant contact with the engine oil in the crankcase. The temperature-sensitive resistor of the spear 2 was connected to the heath. A parallel circuit with the transistor 1F2, a series circuit with the diode 1F, and a series circuit with the diode 2F2.
A series circuit of a diode and a charging capacitor is inserted in parallel, and the transistor of the spear 1 is turned off when the temperature-sensitive resistor of the spear 1 is no longer in contact with engine oil. The transistor of the spear 2 is turned on when the transistor of the spear 1 is turned off, and the transistor of the spear 2 is turned on so as to output the charged charge of the charging capacitor to the output terminal. 1'F
Engine oil detection circuit (3) comprising transistors (3) between both terminals of the primary winding of the ignition coil. The problem with the transistor was that it was located at the voltage dividing point of the voltage dividing circuit, which has a temperature-sensitive resistor connected in series with another resistor, which is installed to come into contact with the engine oil in the crankcase that is scattered by the engine. A series circuit is inserted between the circuit connected to Fang 1 and the diode of Fang 1, and the transistor 1'F1 is turned on when the temperature-sensitive resistor is not in contact with the engine oil. An engine oil detection circuit comprising a spear transistor which is turned on when the transistor is turned on and whose output terminal is connected to the primary winding.