JPH0422458B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lubricating oil contamination level measuring device. The device according to the present invention is used, for example, as an on-vehicle measuring device to measure the concentration of carbon particles contained in the lubricating oil of an internal combustion engine, particularly a diesel engine.

(Prior Art) In internal combustion engines, especially diesel engines, a large amount of carbon particles contained in exhaust gas are mixed into the lubricating oil, so the lubricating oil becomes contaminated in a relatively short time compared to a gasoline engine. Since these carbon particles increase wear on the sliding parts of various parts of the engine, the lubricating oil change intervals for diesel engines are generally shorter than those for gasoline engines, which are almost free from contamination by carbon particles. On the other hand, the degree of contamination of lubricating oil by carbon particles varies greatly depending on the operating conditions of the engine. When driving on expressways, mountain roads, or in taxis, where there are many sudden starts and accelerations, pollution progresses faster than when driving normally. However, the lubricating oil replacement interval has generally been determined solely by the mileage of the vehicle, regardless of these operating conditions. As a result, in some vehicles, lubricant oil may be replaced even though the pollution has not progressed, or conversely, lubricant oil may not be replaced even though it is past time to replace it, resulting in wasted lubricant oil. In some cases, the wear of the sliding parts increased significantly.

Therefore, conventionally known technology is to optically detect the concentration of carbon particles and thereby notify when it is time to replace the lubricating oil. This type of device is disclosed, for example, in Japanese Patent Application Laid-open No. 57-98842 or Japanese Utility Model Application No. 57-98842.
There is a publication number 182152. These devices detect the degree of contamination based on the degree of transparency of the lubricating oil interposed between the light-emitting element and the light-receiving element immersed in the oil, and based on this signal, turn on an indicator lamp etc. to notify the driver of the lubricating oil. This is a warning of pollution.

(Problems to be Solved by the Invention) Contrary to the above publication, for example, in Utility Model Application Laid-open No. 57-182152, the magnitude of the signal is determined continuously over time using a comparator for the output of the light-receiving element, and the display is controlled. are doing. However, the characteristics of light-emitting elements and light-receiving elements generally change depending on temperature. In this case, as is well known, the lubricating oil temperature or the engine compartment temperature varies from about -20°C to a maximum of about 145°C. Therefore, there is a drawback that even if the lubricating oil temperature does not change, the display of the degree of contamination changes. For example, as a light source, a light emitting diode is preferable because of its small size and relatively long life. However, when a light emitting diode is used, in a normal driving method, the light output decreases as the element temperature increases. If the luminescence intensity at 20°C is 1.0, it will drop to about 0.5 at 100°C. Therefore, even if the display indicates that the light is clean when the engine is started with a low oil temperature, as the oil temperature rises, the luminous intensity decreases, and the output of the receiver also decreases, causing the display to appear as if the oil has become contaminated. will be displayed. This has the disadvantage that it repeats every time the engine is operated.

In order to eliminate the above drawbacks, a method of correcting the temperature characteristics of the element using temperature detection means can be considered.
However, in order to correct the device characteristics in the temperature range from -20° C. to 145° C., since the temperature characteristics of the device are generally indirect, a considerably complicated electrical correction circuit is required, which increases the cost.

Furthermore, light emitting diodes have a characteristic that their lifespan is significantly reduced when they are made to emit light at high temperatures. Therefore, in order to use it as a light source for measuring pollution level,
A compensation circuit is required to compensate for changes in detector output due to changes in emission intensity with respect to temperature. Furthermore, it is necessary to stop emitting light at high temperatures.

A technical problem to be solved by the present invention is to accurately detect the degree of contamination of lubricating oil without requiring a temperature correction means such as the above-mentioned temperature compensation circuit.

(Means for Solving the Problems) In order to achieve the above-mentioned technical problems, the present invention provides a measuring means that is immersed in internal combustion engine lubricating oil and detects the degree of contamination of the lubricating oil, and an output of this measuring means. The oil pollution degree measuring device includes a notification means for notifying the degree of pollution based on the temperature detection means for detecting the temperature of the lubricating oil, and the temperature detection means detects that the temperature of the lubricating oil is a predetermined temperature. A technical means is adopted that includes a control means for activating the notifying means based on the measured value output from the measuring means only when the measuring means is activated.

(Function) When the present inventors conducted research on measuring the degree of contamination of lubricating oil, the following two points became clear.

First, the lubricating oil temperature changes periodically within a certain temperature range over the long term as the internal combustion engine starts and stops. Second, the degree of contamination of the lubricating oil does not need to be measured continuously; it is sufficient if it can be measured at appropriate time intervals.

Therefore, by adopting the above technical means,
The degree of contamination of the lubricating oil can be automatically and accurately measured only when the temperature of the lubricating oil is at a predetermined temperature (for example, 50 to 60°C).

(Effects of the Invention) As described above, according to the present invention, since the degree of pollution is detected only at a certain predetermined temperature, stable measurement results can be obtained and the reliability of the apparatus can be improved. Further, since a temperature compensation means for compensating for temperature changes over a very wide temperature range is not required, the configuration is simplified and the manufacturing cost can be reduced.

(Example) FIG. 1 shows a schematic configuration of the apparatus of the present invention, and reference numeral 100 is a pollution level detection sensor (hereinafter referred to as a sensor) which is an example of a measuring means for detecting the pollution level of lubricating oil, and it emits light. A diode 1 and a photodiode 2 are provided. Further, a threaded portion 100a is formed on the body 101 of this sensor, and is screwed into an oil drain port of an oil pan that stores lubricating oil (hereinafter referred to as oil) for an automobile engine. Therefore,
The tip of the sensor 100 is immersed in oil, and the sensor detects that the light emitted from the light emitting diode 1 is
The degree of contamination of the oil is detected based on the degree of attenuation before reaching the photodiode 2 through the oil present in between. In FIG. 1, 202 is a light emitting diode 1
This is a cord for supplying power to the photodiode 2 and extracting the output electricity from the photodiode 2, and a connector 203 for connection is provided at the other end. This connector 2
03 is located in the engine room when the sensor 100 is installed in the oil pan.

On the other hand, a display device 300, which is an example of a notification means for notifying the occupant of the degree of oil contamination detected by the sensor 100, is provided in a highly visible location in the driver's seat of the vehicle. Reference numeral 301 in FIG. 1 is a container that houses a control circuit which is the control means of the present invention, and on the side of this container there is a display section 3 that shows the degree of oil contamination in five stages.
02 is provided. This display section 302 is composed of five light emitting diodes 302a, and as the degree of pollution increases, the light emitting diodes 302a light up to the right in FIG. 1.
In other words, the rightmost light emitting diode 3 out of 5
When 02a lights up, it is designed to notify the occupants that it is time for an oil change. Also container 3
The control circuit inside 00 is connected to the sensor 100 on the engine room side through a connector 303. In this case, the connector 203 and the connector 302 are
The connection is made by a connection cord (not shown) that passes through the dart board between the engine room and the passenger compartment.

Hereinafter, a first embodiment of the present invention will be described in detail.

FIG. 2 shows a cross-sectional view of the sensor 100,
The configuration of the sensor 100 will be explained below using FIG. 2.

The light emitting diode 1 and the photodiode 2 are covered by glass windows 1a and 2a, respectively, and the glass windows 1a and 2a face each other with a predetermined gap 3, and the gap 3 is the one that is to be measured. Filled with lubricant. It is desirable that this gap is 0.34 mm or less in terms of light transmittance.

There is a certain relationship between the degree of contamination of the lubricating oil and the transmittance of light, and as the contamination progresses,
Transmittance decreases, and the amount of light reaching the light emitting element decreases. Therefore, the degree of pollution can be measured by measuring the amount of arriving light using the light receiving element.
However, as the temperature of the light emitting diode 1 changes depending on the temperature of the lubricating oil, and as shown in FIG. It becomes impossible to measure the degree of pollution. In order to solve this problem, the present invention measures the oil temperature using a thermistor 4, which is an example of temperature detection means, in order to measure the lubricating oil temperature when it reaches a set temperature. There is. This thermistor 4 is installed near the light emitting diode 1 and measures the temperature of the oil, that is, the temperature of the light emitting diode.

Next, the configuration of the control circuit housed inside the container 301 shown in FIG. 1 will be explained. FIG. 4 shows the circuit configuration. A voltage is applied to the thermistor 104 from the connection point A via the resistor R ₁ , and the terminal voltage V ₁ of the thermistor is applied to one input terminal of the comparator 10. It seems that it is applied to On the other hand, a voltage corresponding to the set temperature is generated by the voltage divider VR ₁ , and a voltage corresponding to the set temperature is generated by the comparator 10.
is applied to the other end. When the oil temperature increases, the resistance value of the thermistor 4 decreases, and the voltage V ₁ gradually decreases to reach the set temperature (preferably about 50 to 60 degrees Celsius), and when V ₁ becomes lower than the set comparison voltage V ₂ ,
The output of the comparator 10 increases stepwise from the Lo level to the Hi level. This signal inverts the output of flip-flop 11 and applies it to monostable multivibrator 12. This monostable multivibrator 12 generates a single pulse with a width of about 1 second, and this pulse signal turns on the transistor TR ₁ , causing current to flow to the light emitting diode 1 via the load resistor R ₂ and emit light. Ru.

As described above, in this example, the thermistor 4 serving as the temperature detection means is configured so that the light emitting diode 1 lights up only when the oil temperature is at a predetermined value.

On the other hand, the photodiode 2 outputs a photocurrent according to the degree of oil contamination, and this photocurrent is converted into a voltage by an amplifier 13 and applied to a comparator array 14. The comparator array 14 sets some of the output signal lines S ₁ to _{S 5} to a high level depending on the output voltage of the amplifier 13. This signal is sent to the flip-flop array 15.
stores this signal after a certain period of time has elapsed since the light emitting diode 1 started emitting light using a pulse delay signal generated by the monostable multivibrator produced by the delay circuit 16. Also, some of the light emitting diode arrays 18 made up of five light emitting diodes 302 emit light via the transistor array 17 according to the stored signals, and the amplifier 13
Displays the output signal level of the oil, that is, the degree of oil contamination. In addition, the flip-flop array 15 includes
Power is supplied via connection point B from a stabilized power supply 21 shown in FIG. That is, since power is constantly supplied by the stabilized power source 21 connected to the power source 20 without going through the ignition switch 19, the signal continues to be stored even after the engine is stopped. The power source for operating other than the flip-flop array 15 is a stabilized power source 2 connected to a power source 20 via an ignition switch 19, as shown in FIG.
2 via connection point A. For this reason,
When the engine starts, the light emitting diode array 18
displays the previous measured value based on the signal stored in the flip-flop array 16, and also clears the flip-flop 11 and waits for a signal input from the comparator 10 again. Next, a series of operations of the control circuit having the above configuration will be explained using the waveform diagram shown in FIG.

In addition, in FIG. 9, the horizontal axis indicates the passage of time, and the _t1 point in FIG. 9 indicates the starting point of engine starting.
In addition, the vertical axis of waveform diagram A represents the engine lubricating oil temperature, and the waveform diagram B represents the input voltage of comparator 10.
_V1 , and waveform charts C to G represent output waveforms of each component of the control circuit shown in FIG.

When the engine is started, the lubricating oil temperature rises over time as shown in waveform chart A. Along with this, the resistance value of the thermistor 4 decreases, and therefore the voltage V ₁ of the comparator 10 changes to the curve BV ₁ of the waveform diagram B.
It decreases as shown in . And when the value of V ₁ is lower than the reference voltage V ₂ , that is, the oil temperature is about
When the temperature reaches 60 degrees, the output of comparator 10 becomes Hi.
As a result, the flip-flop 11 becomes Hi level as shown in the waveform diagram C. As a result, the monostable multivibrator 12 outputs a pulse as shown in waveform diagram D. While this pulse is being output, a driving current flows through the light emitting diode 1 as shown in the waveform diagram E, and the light emitting diode 1
emits light. The photodiode 2 detects this light according to the degree of contamination of the oil, and outputs a photocurrent according to the degree of contamination of the oil. This photocurrent is converted by the amplifier 31 into a voltage according to the degree of pollution as shown in the waveform diagram F. This voltage value is input to the comparator array 14, and an output signal line corresponding to the degree of pollution is selected from among the signal lines _S1 to _{S5 and} output.

Then, when the output of the amplifier 13 becomes stable, the set signal of the flip-flop array 15 is outputted as shown in the waveform diagram G, and the set signal of the flip-flop array 15 is output as shown in the waveform diagram G.
4 output level is flip-flop array 15
The light emitting diode 302 corresponding to the degree of pollution is stored in the display light emitting diode array 18.
a is lit. Said flip-flop array 1
5, since the stabilized power supply 21 is energizing the engine while the engine is stopped, the stored previous measured value is displayed again when the engine starts operating next time.

As described above, the first embodiment employs a method in which the light emitting diode 1 emits light for a short time only when the lubricating oil reaches a preset temperature, measures the degree of pollution, and displays and stores the measured value. Therefore, measurements are always performed up to a constant temperature, eliminating the need for a compensation circuit that compensates for changes in light emission intensity due to temperature of the light emitting diode 1, and since the light emitting diode 1 does not emit light at high temperatures. It has an excellent feature of being able to significantly lengthen the life of the diode 1.

In the first embodiment, the thermistor 4 provided in the sensor 100 is used as the oil temperature detection means, but the present invention is not limited to this as long as the oil temperature can be detected. If an oil temperature sensor is provided, its signal may be used. Also, the oil temperature and engine cooling water temperature are
Since there is some correlation, the signal from the engine's cooling water temperature sensor may also be used. However, when using these, a signal line is required to connect the number of temperature sensors and the pollution measuring device.

Next, other embodiments of the present invention will be described.
In the above embodiment, as the oil temperature measuring means,
A case where the thermistor 4 provided in the sensor 100 is used is shown. The second embodiment uses the temperature characteristics of the light emitting diode 1 to eliminate the need for special temperature detection means such as the thermistor 4. When a minute current of about 1 mA is passed through the light emitting diode 1 in the forward direction, the voltage appearing at the terminals of the light emitting diode 1 changes depending on the temperature of the element. This is shown in FIG. The terminal voltage V _F generated at the terminal when a small current is passed in the forward direction through the light emitting diode 1 (not limited to this but a diode in general) decreases as the temperature rises. In the case shown in Figure 6, approximately -7.4
A voltage change of mV/°C occurs. Since the reproducibility of this voltage with respect to temperature is very good, the temperature of the element (≈oil temperature) can be detected by measuring this voltage, and no special temperature detection means is required.

A control circuit of this second embodiment is shown in FIG. The same reference numerals as in FIG. 4 indicate the same components. The difference from the embodiment shown in FIG. 4 is that the light emitting diode 1 has two load resistors with resistance values R ₁ and R ₂ as load resistors, and the value of the load resistor is switched by a relay 30. and that the terminal voltage V _F of the light emitting diode 1 is used as an input to the temperature detection comparator 10. When energized (when measuring temperature), relay 1 is open.
A current of about ₁ mA is passed through the light emitting diode through a load resistor R1 having a relatively high resistance value (5 to 6 KΩ, although it is inferior to the power supply voltage). As the oil temperature rises, the terminal voltage V _F of the light emitting diode 1, that is, the input voltage V ₃ of the comparator 10 gradually decreases as shown by the curve BV ₃ in the waveform diagram B in FIG _. temperature), the output of the comparator 10 rises stepwise from the Lo level to the Hi level, the output of the flip-flop 11 is inverted, and the monostable multivibrator 12 generates a pulse signal of about 1 second. This signal causes
Transistor TR ₁ becomes conductive, relay 30 closes, current flows through light emitting diode 1 via load resistor R ₂ of relatively low resistance, and light is emitted.
When the relay 30 is closed, the terminal voltage V _F of the light emitting diode increases. Next, when the pulse signal ends and the relay 30 opens, V _F decreases, so
Accordingly, the comparator 10 issues a signal again, but since the flip-flop 11 has already been inverted, the output of the flip-flop 11 does not change.
The monostable multivibrator 12 will not output a pulse signal again. Incidentally, the flip-flop 12 is reset when the power is next turned on by the ignition key 19. The method of driving the light emitting diode array 18 is the same as in the previous embodiment.

By the above method, the oil temperature detection thermistor 4 can be made unnecessary.

Next, a third embodiment of the present invention will be described.

The light emission intensity of the light emitting diode 1 used in the sensor 100 and the temperature dependence of the terminal voltage of the light emitting diode 1 when a minute current is passed vary considerably depending on the individual elements. Therefore, certain measures are required to make each sensor compatible. An example of a compatible sensor 100 and display circuit is shown in FIG. In order to provide compatibility, the following points differ from the previous embodiments. first,
One of the features of the present invention is that the terminal voltage of the light emitting diode 1 changes depending on the temperature as a means for detecting the oil temperature, but this terminal voltage varies depending on the individual light emitting diodes 1.
Therefore, in the third embodiment, the sensor 100 includes
A variable resistor called _R3 is provided. _R3 , _R4
The terminal voltage of light emitting diode 1 is divided by
It is input to the input terminal of the comparator 10. With the above configuration, variations in the terminal voltage of the individual light emitting diodes 1 can be reduced by adjusting the adjustment resistor R ₃ connected to the sensor 100, so that the terminal voltage of the light emitting diodes 1 can be made the same for the temperature of the sensor 100. They can be aligned and create compatibility.

Next, since the light emission intensity of the light emitting diode 1 and the sensitivity of the photodiode 2 also vary depending on the individual elements, adjustment for this is also necessary. Therefore, a variable resistor _R5 is provided to adjust the variation in sensor output. This resistor _R5 and the adjusting resistor _R3 are attached to the connector 203, for example, as shown in FIG. The photocurrent flowing through the photodiode 2 is amplified by an amplifier 31 and converted into a voltage. This voltage is further amplified by an amplifier 32 and then sent to a comparator array 15. Here, the amplification degree by the amplifier 32 is R ₆ , R ₅
determined by the ratio of Therefore, by adjusting the resistance value of _R5 , the final output of the sensor 100 can be adjusted. On the other hand, since R ₅ is installed on the same rack as the sensor 100, when the sensor 100 is replaced, R ₅ is also replaced at the same time, and the sensor 100 is also replaced.
Since the optimum resistance value is inserted at 0, the sensor 10
0 can be made compatible.

The circuit shown in FIG. 8 is also equipped with a reset circuit 33 and a waveform shaping circuit 34, and includes a flip-flop 11 and a monostable multivibrator 12.
is reset by the reset circuit 33 when the ignition switch 19 is turned on. In addition, the waveform shaping circuit 34 allows the comparator 10
The output waveform of is shaped and input to flip-flop 11.

As described above, according to the third embodiment, the oil temperature detection temperature adjustment resistor R ₃ and the sensitivity adjustment resistor R ₅
By placing the sensor 100 on the same rack as the sensor 100, the oil temperature detection temperature and pollution level detection sensitivity can be improved by each sensor 10.
0, all can be adjusted the same and the sensor 100 can be made compatible.

The present invention can be modified in various ways in addition to the embodiments described above, and the method of measuring only when the oil temperature reaches a certain temperature is not limited to the method of determining the degree of contamination by light transmittance. , for example, detecting oil deterioration by changes in the dielectric constant of lubricating oil, or detecting oil deterioration by changes in viscosity, electrical resistance, alkalinity, and acidity. Therefore, it goes without saying that this method is also effective when using a measurement method that has the characteristic of changing measured values.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of the present invention, FIG. 2 is a partial cross-sectional view of FIG. 5 and 5 are electric circuit diagrams of the first embodiment of the present invention, FIG. 6 is a characteristic diagram showing the terminal voltage with respect to the temperature of the light emitting diode, and FIG. 7 is an electric circuit diagram of the second embodiment of the present invention. FIG. 8 is an electric circuit diagram of the third embodiment of the present invention, and FIG. 9 is the electrical circuit diagram of the third embodiment of the present invention.
FIG. 9 is a waveform chart showing operation signal waveforms of various parts in response to changes in lubricating oil temperature in FIGS. 1... Light emitting diode, 2... Photo diode, 4... Thermistor, 100... Pollution detection sensor, 300... Display detection, 302a... Light emitting diode for display.

Claims (1)

[Scope of Claims] 1. An oil pollution degree measuring device that is immersed in internal combustion engine lubricating oil and includes a measuring means for detecting the degree of contamination of the lubricating oil, and a reporting means for notifying the degree of pollution based on the output of this measuring means, temperature detection means for detecting the temperature of the lubricating oil; and only when the temperature detection means detects that the temperature of the lubricating oil is a predetermined temperature, the 1. A lubricating oil contamination level detection device comprising: a control means for activating a notification means. 2. The control means includes a holding means for holding the measured value outputted from the measuring means regardless of whether the internal combustion engine is running or stopping, and a notifying means based on the held measured value while the internal combustion engine is running. and a replacement means that replaces the held measured value with a new value output from the measuring means for each measurement. The lubricating oil contamination level measuring device according to item 1. 3. The pollution degree measuring means is composed of a light-emitting element and a light-receiving element, and the control means measures the pollution degree by a signal corresponding to the intensity of light that passes through lubricating oil interposed between both elements and reaches the light-receiving element. Claim 1 is characterized in that it calculates
The lubricating oil contamination level measuring device according to any one of Items 1 and 2. 4. The lubricating oil contamination level measuring device according to claim 3, wherein the light emitting element and the light receiving element are a light emitting diode and a photodiode, respectively. 5. The temperature detection means is configured to send a small current through the light emitting diode in a forward direction and detect the temperature of the lubricating oil based on the voltage drop generated in the light emitting diode. The lubricating oil contamination level measuring device according to item 4. 6. Claim 1, wherein the notification means is constituted by a plurality of indicator lights, and the degree of pollution is displayed in stages according to the number of store lights of the indicator lights.
The lubricating oil contamination level measuring device described in 2.