JP2003028840A - Method and apparatus for judging deterioration of engine oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus capable of judging the deterioration of engine oil in a short time even during the running of a car. SOLUTION: The apparatus for judging the deterioration of the engine oil is equipped with a pair of electrodes 5 and 5 immersed in the engine oil 7 in a state opposedly arranged so as to leave an interval, a high voltage power supply 8 connected to one of the electrodes 5 and 5 and a detection circuit 25 provided on the side of the other electrode to detect the continuity between the electrodes. The deterioration of the engine oil 7 is judged on the basis of the detection signal from the detection circuit 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a judging device for automatically judging the deterioration condition of engine oil used in an automobile or the like by utilizing a dielectric breakdown voltage.

[0002]

2. Description of the Related Art The properties of automobile engine oil are kinematic viscosity,
The total acid number, total base number, n-pentane insoluble matter amount, gasoline dilution amount, etc. are analyzed, and judgment is made based on the analyzed values.
Among these, the kinematic viscosity and the total acid value are most effective for judging the deterioration of the engine oil. First, regarding the kinematic viscosity, for example, two electrodes are arranged in engine oil stored in an oil pan, an AC voltage is applied by these electrodes, the capacitance between the electrodes is measured, and the obtained value is obtained. It is measured by the method of detecting deterioration of engine oil from.

The analysis of the total acid value is generally carried out by utilizing the potentiometric titration method. What is this potentiometric titration method?
As specified in JIS, a sample of engine oil or the like is dissolved in a mixed solvent of toluene, 2-propanol and water, and titrated with a potassium hydroxide standard 2-propanol solution using a glass electrode and a reference electrode. This is a method of measuring the acid value. Two electrodes (glass electrode, reference electrode) on the sample
The pH of the sample is measured by immersing in the sample and detecting the potential difference generated between the electrodes, and the relationship between the pH meter reading and the corresponding titration amount of the standard solution is expressed in a titration curve. From this titration curve, The obtained inflection point is the end point. In addition, JP-A-6-2
Japanese Patent No. 01649 describes a technique of immersing a pair of electrodes in engine oil and measuring the voltage generated between these electrodes to estimate the total acid value corresponding to this voltage. The principle of this method is that an electric charge is accumulated in the electrode by immersing the electrode in engine oil, and the voltage is estimated from the accumulated electric charge, and the voltage is not applied from the outside.

[0004]

However, in the potentiometric titration method, a potentiometer is used, which facilitates automation. On the other hand, potentiometric titration of a non-aqueous solution such as engine oil results in a slow response and a long measurement time. There was a problem of cost. Further, in this potentiometric titration method, the automobile must be stopped and the engine oil must be sampled from the automobile and measured, which cannot be automatically measured during traveling.
In addition, engine oil should be judged not only based on kinematic viscosity but also on other factors, and it is very difficult to judge deterioration based on only one factor. That is, it is desirable to determine the deterioration state of the engine oil from both the kinematic viscosity and the total acid value.

Further, in JP-A-6-201649, JP-A-6-66124, JP-A-5-23121, and JP-A-10-78402, the relationship between the electric resistance of the engine oil itself and the amount of metal wear powder is shown. I'm watching. As shown in FIG. 8, the present inventors have also found that the electric resistance and the total acid value, or FIG.
As shown in (1), the relationship (100 kHz) between the n-pentane insoluble matter and the resistance was examined, but no clear correlation was found.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide a deterioration judging method and deterioration judging device for engine oil, which can judge even while the automobile is running and can judge in a short time. To do.

[0007]

In order to achieve the above-mentioned object, a method for judging deterioration of engine oil according to the present invention is a method in which a pair of electrodes is immersed in engine oil and the distance between the electrodes is constant. A measurement step of measuring the dielectric breakdown voltage or measuring the inter-electrode distance at which dielectric breakdown occurs when the voltage applied between the electrodes is constant, and the measured voltage or the inter-electrode distance is less than or equal to a predetermined deterioration reference value. If
And a determining step of determining that the engine oil has deteriorated. The deterioration state of engine oil is mainly determined by the total acid value and the kinematic viscosity. Among these, the present invention is a method of managing the total acid value by a dielectric breakdown voltage instead. If the breakdown voltage as the deterioration reference and the inter-electrode distance at that time are determined in advance, the deterioration of the engine oil can be easily determined by measuring the breakdown voltage of the engine oil.

When this method is used, not only the total acid value but also n
-Amount of pentane insoluble can be analyzed in a shorter time than before. Further, since the output can be obtained from the ignition coil of the automobile, it is possible to dispose the deterioration determination device without changing the vehicle structure so much and it is possible to perform the measurement even while the vehicle is running. And
Measuring and controlling the breakdown voltage is at the same time indicative of an increase in the inclusion of conductive particles, conductive ions and contaminants.

Furthermore, in one aspect of the engine oil deterioration determination method according to the present invention, the deterioration reference value is a dielectric breakdown voltage corresponding to the total acid value of the deteriorated engine oil. In general, engine oil is judged to have deteriorated when the total acid value of the new oil + the total acid value of 2 to 3 mgKOH / g (for example, 5 mgKOH / g) or more. Therefore, the voltage at which dielectric breakdown corresponding to this total acid value (distance between electrodes is constant) or the distance between electrodes at which dielectric breakdown corresponding to this total acid value occurs (voltage is constant) is grasped, and these are degraded. If used as a reference value, it can be determined whether the engine oil has deteriorated and is in a stage to be replaced.

Another aspect of the method for determining deterioration of engine oil according to the present invention is that the measurement step is performed a plurality of times.
In the determining step, the number of times of being equal to or less than the deterioration reference value is measured, and when the number of times is equal to or more than a predetermined reference number, it is determined that the engine oil is deteriorated. If the same voltage as the reference breakdown voltage is applied only once, an erroneous determination may occur. Therefore, if the deterioration determination reference number is set in advance and it is judged as deterioration when the number of times of dielectric breakdown is equal to or more than the deterioration determination reference number, it is possible to make a highly reliable determination.

The engine oil deterioration determination apparatus according to the present invention is a device for immersing a pair of electrodes immersed in engine oil in a state of being opposed to each other with a gap, and a high-voltage power supply connected to one of these electrodes. And a detection unit that is provided on the other side of the electrodes and that detects that a current has flowed between the electrodes, and determines deterioration of the engine oil based on a detection signal from the detection unit. There is. Since this deterioration determining device can be installed in various vehicles having an engine, the deterioration determining device can be attached easily and at low cost.

In one aspect of the engine oil deterioration determining apparatus according to the present invention, the electrodes are arranged in an oil pan filled with engine oil, and an automobile battery and an ignition coil are used as the high voltage power source. At the same time, a photo coupler is arranged in the detection circuit. This deterioration determining device can be installed in a vehicle and can use an existing battery, ignition coil, or the like,
The cost can be kept low without making a major modification to dispose the determination device. Further, since the photocoupler is used in the detection circuit and the primary side and the secondary side can be completely insulated from each other, it is difficult to be influenced by the disturbance noise and accurate determination can be performed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an engine oil deterioration determination method and a deterioration determination device according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention measures, among the properties of automobile engine oils, the dielectric breakdown voltage at a constant interelectrode distance or the interelectrode distance at which a dielectric breakdown occurs at a constant voltage, which is correlated with the total acid number, and is a constant reference value. If the temperature falls below the range, the engine oil deteriorates and the apparatus used in the method. The performance deterioration of engine oil is mainly judged by the kinematic viscosity and the total acid value, but the present invention is a method for efficiently measuring the total acid value out of them by the dielectric breakdown voltage.

[Principle of the Invention] The engine oil of an automobile is
Lubricating oil that reduces sliding resistance when a piston in an engine slides in a cylinder bore. During operation of the engine, the temperature inside the engine becomes extremely high, and contaminants such as metal abrasion powder on the piston and cylinder bores dissolve into the engine oil.As the vehicle travels longer, the engine oil dissociates. The amount of contaminated ions increases. When the amount of the contaminant ions increases, the amount of the rancid substances and rancid ions increases, and the engine oil deteriorates. On the other hand, engine oil is originally a substance having an insulating property, but when the amount of contaminant ions increases, the conductivity becomes better and the dielectric breakdown voltage value decreases. The contaminants include, in addition to the metal powders, organic acids, inorganic acids, esters, phenol compounds, lactones, resins, heavy metal salts, etc., each of which has many acidic components, so that when the amount of contaminant ions increases, The acid value increases.

Therefore, when the engine oil deteriorates, the amount of contaminant ions increases, the total acid value increases, and the dielectric breakdown voltage decreases. As shown in FIG. 4, which will be described later, there is a clear correlation that these total acid value values and dielectric breakdown voltage values are inversely proportional to each other. That is, when the value of total acid value increases, the conductivity is improved, and the dielectric breakdown voltage value decreases in inverse proportion to this. Therefore, the present inventors have come to the idea that the deterioration state of the engine oil can be determined by measuring the dielectric breakdown voltage value as a substitute characteristic of the total acid value.

Generally, the total acid value is 5.0 mgKOH / g
Since it can be determined that the engine oil has deteriorated under the above conditions, it is determined that the engine oil has deteriorated when the dielectric breakdown voltage value becomes a value corresponding to this 5.0 mgKOH / g, for example, 30.0 kV or less. can do. However, the breakdown voltage increases as the distance between the electrodes increases,
The 30.0 kV is the value of the dielectric breakdown voltage when the distance between the electrodes is 2.5 mm.

[Setting of Degradation Criteria] As described above,
The dielectric breakdown voltage value corresponding to a certain total acid value changes depending on the distance between the electrodes. Therefore, first, after determining the total acid number that is the criterion for deterioration of engine oil, set the dielectric breakdown voltage corresponding to the total acid number at a constant interelectrode distance or the interelectrode distance at which constant voltage causes dielectric breakdown. To do. That is, the distance between the electrodes is kept constant, and the voltage is gradually increased in this state, and the voltage value at the time of dielectric breakdown is set as the dielectric breakdown voltage, or the voltage value is kept constant and in this state The electrodes may be gradually brought close to each other to determine the distance between the electrodes when dielectric breakdown occurs. Then, when the same voltage as the dielectric breakdown voltage is simply applied once in the engine oil, there is a risk of erroneous determination due to a malfunction or the like due to some influence, and thus there may be insufficient reliability. Therefore, the voltage is applied for a certain time (t ₀ ) using a timer or the like.
During this period, it is preferable to determine “deterioration” when dielectric breakdown occurs more than a predetermined reference number (n ₀ times) as a result of applying a plurality of times (n times). The preferable ranges of the time and the number of times are as follows: the constant time t ₀ is 2 to 10 seconds, the number of application times n is 20 to 100 times, and the reference number of times n ₀ is 5 to 20 times.

[Deterioration Determining Device] As shown in FIG. 1, the deterioration determining device according to the present invention has a spherical electrode 5 arranged in an oil pan 3 provided in a lower portion of an engine 1, and the oil pan is provided in this oil pan. This is a device for measuring the dielectric breakdown voltage of the accumulated engine oil 7. As shown in FIG. 2, the electrodes 5 are attached to an electrode fixing plate 9 in a state of being separated from each other by a constant distance, and a peripheral portion of the electrode fixing plate 9 is sealed by an O-ring 11. A lead wire 13 is connected to the electrode 5, and as shown in FIG. 3, an ignition coil 19 and a battery 20 are provided at one end of the lead wire 13 via a backflow prevention diode 15 and a switch 17. Is connected to a high voltage power supply 18, and the other end is connected to a detection circuit 25 having a photo coupler 23 via a timer 21.

The switch 17 is provided for connecting the detection circuit 25 to the ignition coil 19 when it is desired to determine the deterioration state of the engine oil 7. The ignition coil 19 is connected to the high-voltage power distribution section of the distributor 27, and the spark plug 29 connected from the rotor is switched in the distributor 27. Further, the timer 21 is configured such that the current is conducted only for the deterioration determination time t ₀ seconds. In the photocoupler 23, when a current flows through the primary side 31, the light generated by this current is detected by the secondary side 33. Further, the photocoupler 23 includes the counter 37, the comparison unit 39, and the display unit 4 via the transistor 35.
Connected to 1. The counter 37 counts the number of inputs from the low pulse to the high pulse at the point B, and sends this number to the comparison unit 39 as a pulse. Here, if the low pulse is input to the high pulse once, the dielectric breakdown is counted as one occurrence. The electrode 5
May be configured so as to extend outward from the oil pan 3 and form a pipe (not shown) so as to return to the inside of the oil pan 3 and to dispose the pipe inside the pipe.

[Detection Procedure] First, when a voltage of, for example, 12 V is applied from the battery 20, the voltage is boosted by the ignition coil 19, and the boosted voltage is guided to the high-voltage power distribution section of the distributor 27. In this high-voltage distribution unit, as a result of switching the spark plug 29 connected from the rotor, the electrode units of each spark plug 29 are sequentially discharged. Therefore, when the distributor 27 and the electrode 5 are connected in parallel and the boosted voltage is directly applied to the electrode 5 in the engine oil 7, a current flows between the pair of electrodes 5 and 5 arranged to face each other, causing deterioration. The engine oil 7 that has been caused causes a dielectric breakdown.

Due to this dielectric breakdown, the photocoupler 23
An electric current flows through the primary side 31 to emit light, and this light is emitted from the secondary side 3
Detected in 3. During the judgment time t ₀ seconds, a dielectric breakdown voltage of the deterioration reference value is applied, the number of times of dielectric breakdown per judgment time t ₀ seconds is measured by the counter 37, and the comparison unit 39 counts the number of dielectric breakdown and the deterioration judgment reference number n. _{When the} number of dielectric breakdowns is equal to or greater than the deterioration determination reference number n ₀ , it is determined to be degraded. The result of comparison between the number of dielectric breakdowns and the deterioration determination reference number n ₀ is sent to the display unit 41 as a pulse indicating deterioration or non-deterioration, and the display unit 41 displays whether deterioration or non-deterioration is performed.

[0022]

EXAMPLES Next, the present invention will be described more specifically by way of examples. In this example, a voltage having the same value as the dielectric breakdown voltage, which is the deterioration reference value, was applied during the determination time of 10 seconds, and the deterioration state of the engine oil 7 was examined. First, when the engine oil 7 deteriorates, the dielectric breakdown voltage corresponding to the total acid value of 5.0 mgKOH / g is 3 as shown in the graph of FIG.
It became 0.0kV. The distance between the electrodes 5 and 5 at this time was 2.5 mm.

When a deterioration determining device is installed in an automobile, the engine speed during idling is usually 1000 rp.
Since it is m, the plug is ignited 83 times in 10 seconds, and the voltage is applied 83 times in 10 seconds. However, in this embodiment, in order to simplify calculation and explanation, as shown in FIGS. 5 and 6, ignition of the plug (indicated by an asterisk) occurs 10 times during the deterioration determination time t ₀ : 10 seconds. Assuming that the breakdown voltage is the same as the breakdown voltage (30 k
V) was applied 10 times as indicated by the arrow. The deterioration determination voltage and the distance between the electrodes are values corresponding to a total acid value of 5 mgKOH / g.

Then, the number of deterioration determinations n _{0 is set} to 5 and 1
It was determined that the engine oil 7 had deteriorated when the dielectric breakdown occurred 5 times or more with respect to the voltage application of 0 times. Therefore, as shown by circles in FIG. 5, when the number of dielectric breakdowns was 3, it was determined that the state was not deteriorated, and as shown in FIG. 6, when it was 6, it was determined that the state was deteriorated. Note that not only the relationship between the total acid value and the dielectric breakdown voltage, but also the relationship between the n-pentane insoluble content and the dielectric breakdown voltage was examined and shown in FIG. 7.

[0025]

According to the present invention, it is possible to determine deterioration of engine oil in a shorter time than in the conventional case. Further, since the output can be obtained from the ignition coil of the automobile, it is possible to dispose the deterioration determination device without changing the vehicle structure so much and it is possible to perform the measurement even while the vehicle is running. Then, by measuring and managing the dielectric breakdown voltage, at the same time, it becomes a measure that the mixture of conductive particles, conductive ions and contaminants is increased.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an engine provided with a deterioration determination device according to the present invention.

2 is a sectional view showing an enlarged part P of FIG. 1, and FIG. 2 (b) is a front view of FIG. 2 (a).

FIG. 3 is a circuit diagram in the deterioration determination device according to the present invention.

FIG. 4 is a graph showing the relationship between total acid value and dielectric breakdown voltage.

FIG. 5 is a graph showing an example in which a deteriorated state was investigated by applying a voltage to undeteriorated engine oil.

FIG. 6 is a graph showing an example in which a deteriorated state is investigated by applying a voltage to deteriorated engine oil.

FIG. 7 is a graph showing the relationship between the n-pentane insoluble matter and the dielectric breakdown voltage.

FIG. 8 is a graph showing the relationship between total acid value and resistance.

FIG. 9 is a graph showing the relationship between n-pentane insoluble matter and resistance.

[Explanation of symbols]

1 engine 3 oil pan 5 electrodes 7 engine oil 9 Electrode fixing plate 11 O-ring 13 lead wire 15 Backflow prevention diode 17 switch 18 High voltage power supply 19 ignition coil 20 battery 21 timer 23 Photocoupler 25 detection circuit 27 Distributor 29 spark plugs 31 Primary side 33 Secondary side 35 transistor 37 counter 39 Comparison Department 41 Display

Claims (5)

[Claims] 1. A pair of electrodes is immersed in engine oil to measure a dielectric breakdown voltage when the distance between the electrodes is constant, or dielectric breakdown occurs when a voltage applied between the electrodes is constant. And a determination step of determining that the engine oil has deteriorated when the measured voltage or the distance between electrodes is equal to or less than a predetermined deterioration reference value. Deterioration determination method for engine oil. 2. The method for determining deterioration of engine oil according to claim 1, wherein the deterioration reference value is a dielectric breakdown voltage corresponding to a total acid value of deteriorated engine oil and a distance between electrodes. 3. The measurement step is performed a plurality of times, and in the determination step, the number of times the deterioration reference value is not more than is measured, and when the number of times is not less than a predetermined reference number, it is determined that the engine oil is deteriorated. The method for determining deterioration of engine oil according to claim 1 or 2. 4. A pair of electrodes immersed in engine oil in a state of being opposed to each other with a gap, a high-voltage power source connected to one of these electrodes, and a high-voltage power supply provided on the other side of said electrodes, An engine oil deterioration determination device, comprising: a detection unit that detects that an electric current has flowed between the electrodes, and the deterioration of the engine oil is determined based on a detection signal from the detection unit. 5. An electrode arranged in an oil pan of an automobile filled with engine oil is used as the electrode, and an automobile battery and an ignition coil connected to the automobile battery are used as the high-voltage power source. The engine oil deterioration determination device according to claim 4, wherein a photocoupler is provided in the detection means.