JPH10185906A - Method and apparatus for testing piston cleaning ability of marine lubricating oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a test method and a test apparatus capable of evaluating the piston cleaning ability of marine lubricating oil easily and in a short time, and excellent in the repeatability of a test result. SOLUTION: In this test method, first of all, a preparatory test is performed by using a diesel engine, a high engine speed, a high lubricating oil temperature, and a high coolant temperature are set beforehand within a range where the engine is not damaged including scuffing. Next, the diesel engine is operated with a sample lubricating oil for a specified time under the conditions of the engine speed, oil temperature, and coolant temperature set. Moreover, its piston cleaning ability is evaluated according to the already-known piston cleaning ability evaluating standards for land diesel engines. A testing apparatus 10 is provided with a diesel engine 12, a dynamometer 14, fuel systems 18, 20, an intake system 22, an exhaust system 24, and an engine controller 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for testing piston cleanliness of marine lubricating oil, and more particularly to a method and apparatus for evaluating piston cleanliness of marine lubricating oil in a short time and with high reproducibility. is there.

[0002]

2. Description of the Related Art Piston cleanliness evaluation test of marine lubricating oil is performed by measuring the amount of carbon adhering to the piston of an engine, clogging of a piston ring, etc. It is a test to evaluate.
Conventionally, piston cleanliness evaluation tests have been carried out using actual lubricating oil for the actual ship's engine using the lubricating oil sample, and a bench test using the engine used in the actual ship. The test is carried out by a hot tube test method, which is evaluated at the laboratory and laboratory levels. Generally, the cleanliness of lubricating oil is evaluated by a bench test method using a marine engine of Bornes.

[0003]

However, each of the conventional test methods has the following problems.
It was not always an established test method. First of all, the actual ship test method is the most practical test method, and the most reliable practical evaluation can be performed. In addition, since it is difficult to reproduce the same driving state in different voyages, the evaluation differs for each voyage, and there is a problem that the reproducibility of the evaluation result is low. In addition, using lubricating oil of a sample whose evaluation has not been determined for actual voyage may hinder voyage, and there is also a problem that it is practically difficult to use it on an actual ship. . In addition, the bench test method using an engine used in an actual ship, for example, a marine engine by Bornes, requires a relatively short time for evaluation and a high repeatability of test results as compared with the actual ship test method.
The use of a large engine requires the installation of dedicated equipment, and the use of a large amount of fuel and lubricating oil increases the cost. In addition, the hot tube test method is simple and the time required for the evaluation is short, but the evaluation result only shows one index of the cleanliness of the piston, and the correlation with the cleanness evaluation of the actual ship test method. Was a problem.

[0004] Therefore, there has been a demand for an economical test method which has a high correlation with the evaluation result of the actual ship test method or the bench test method, is simple, and requires a short time for the evaluation. The present invention
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a test method and a test apparatus which can easily and quickly evaluate the cleanliness of a marine lubricating oil piston and have excellent reproducibility of test results. .

[0005]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that among many factors affecting the cleanliness of marine lubricating oil pistons, the heat input to the engine (the engine heat per unit time) The calorific value of the fuel supplied to the engine, the engine speed, the excess air ratio, the oil temperature of the lubricating oil in the engine, the liquid temperature of the engine cooling water, and the exhaust pressure were found to be the main factors. In particular, the heat input, the engine speed, the excess air ratio, the oil temperature of the lubricating oil and the liquid temperature of the engine cooling water greatly affected, and it was found that these fluctuations were the main factors of the dispersion of the test results. Therefore, the present inventors have focused on the fact that it is necessary to strictly control these factors, particularly the main factors, in order to increase the reliability of the test method and the evaluation obtained by the test method, and repeated experiments. As a result, the method and apparatus for testing the cleanliness of a piston of a marine lubricating oil according to the present invention have been completed.

Accordingly, in order to achieve the above object, a piston cleanliness test apparatus according to the present invention is provided with a light oil combustion type diesel engine capable of freely adjusting a fuel injection amount, an oil temperature of lubricating oil and a liquid temperature of coolant. , A test apparatus main body having a dynamometer for applying a load to a diesel engine, a heavy fuel oil supply system for supplying heavy fuel oil to the diesel engine, and regulation of excess air ratio for supplying combustion air to the diesel engine It is characterized by including a free intake system and a control device for controlling the engine speed of the diesel engine, the oil temperature of the lubricating oil, and the liquid temperature of the coolant under a predetermined load to predetermined values.

[0007] A method for testing piston cleanliness of marine lubricating oil according to the present invention is a test method for evaluating piston cleanliness of marine lubricating oil using the above-described apparatus for testing piston cleanliness of marine lubricating oil. Preliminary tests are conducted in advance using heavy fuel oil as fuel, and at least engine speed and oil temperature of lubricating oil among the factors affecting piston cleanliness as far as engine damage including scuffing does not occur. And setting the liquid temperature of the coolant to the highest possible rotational speed and temperature, respectively, and using heavy fuel oil as fuel under the set engine speed, oil temperature and liquid temperature conditions, Operating the diesel engine with the lubricating oil for a predetermined time; and evaluating the piston cleanliness according to the known land diesel engine piston cleanliness evaluation standard. Tsu is characterized in that it comprises a flop.

Hereinafter, the present invention will be described in detail. If the excess air ratio is too low, stable combustion of the fuel cannot be maintained in the engine combustion chamber, and if it is too high, it is difficult to distinguish a difference in piston cleanliness between oil types of lubricating oil. Increasing the engine speed or increasing the oil temperature of the engine lubricating oil and the coolant temperature, and increasing the cylinder liner temperature will increase the severity of piston cleanliness. Differences in piston cleanliness can be clearly distinguished between species. The heat input shall be the minimum amount that can maintain the required engine speed. When the heat input increases, the engine speed increases and the severity of the piston cleanliness increases.However, in the cleanliness evaluation test, the difference in fuel properties greatly affects the test results. This is because it is desirable that the test can be performed many times.
Scuffing generally refers to a scratch between metal and metal, and in the present invention, refers to a scratch generated between a piston and a cylinder liner. The occurrence of scuffing of the piston parts means that the engine is operating in a region where the lubricating oil is not functioning. So this is
It is that the piston cleanliness of the lubricating oil is evaluated at places other than the original use conditions of the lubricating oil. In other words,
This means that the test was performed in an area where it is meaningless to perform the piston cleanliness evaluation test.

The method of the present invention can be applied to the evaluation of piston cleanliness of all types of marine lubricating oils, and is particularly suitable for marine diesel engine oils, and includes marine lubricating oils containing additives and other components other than lubricating oils. , So-called marine system cylinder oil. As a base oil for marine lubricating oil (hereinafter simply referred to as lubricating oil), mineral oil, synthetic oil and the like are usually used.
Examples of the additives include various additives such as a metal type detergent, a dispersant, an antioxidant, an extreme pressure agent, and an antifoaming agent. The heavy fuel oil used in the present invention may be any one as long as it is used in a marine engine. Generally, fuels used in marine engines include A, B, and C heavy oils, and it is preferable to use heavy oil equivalent to JIS K2205 specified in JIS for evaluation.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1. Example of Test Apparatus According to the Present Invention As shown in FIG. 1, a test apparatus 10 according to the present embodiment supplies an apparatus main body 16 including an engine 12 and a dynamometer 14 for applying a load to the engine 12, and supplies heavy fuel oil. A heavy fuel oil supply system 18, a light oil supply system 20 for supplying light oil when the engine is started, and an intake system 2 for supplying combustion air to the engine 12
2, an exhaust system 24 for exhausting exhaust gas from the engine 12,
And a controller 26 for controlling operating conditions of the engine.
It has.

The engine 12 is a diesel engine using light oil as fuel, and is provided with a heating / cooling means capable of adjusting the temperature of the engine lubricating oil and the temperature of the engine cooling water. The number of cylinders of the engine may be either single cylinder or multiple cylinders. Further, the fuel injection system may be either a direct injection system or an indirect injection system. The displacement of the engine is not particularly limited, but is preferably 1,000 to 1
Those in the range of 000 cc are good. When the engine displacement exceeds 10,000 cc, the scale becomes almost the same as that of an actual ship engine, which is not preferable for a bench test. The dynamometer 14 is provided to apply a load to the engine 12, and may be a generally used dynamometer as long as it can apply a load corresponding to the maximum output of the used engine. Examples include a dynamometer, a water dynamometer, a hydraulic dynamometer, a DC dynamometer, an AC dynamometer, and the like.
The engine 12 and the dynamometer 14 may be directly connected to the dynamometer and the engine shaft, but it is practical to connect the dynamometer and the engine shaft via a transmission such as an automatic transmission or a manual transmission. When the single cylinder engine is directly connected to the dynamometer, a flywheel is desirably provided between the dynamometer and the engine to suppress fluctuations in the engine speed, and the inertia force of the flywheel is used.

The fuel supply system is composed of two systems, a heavy fuel oil supply system 18 and a light oil supply system 20, and is appropriately switched by a switching mechanism 28 having a known structure.

The heavy fuel oil supply system 18 includes a heavy fuel oil tank 30, an intermediate tank 32 for heavy fuel oil, and a fuel consumption meter 3.
4 and a buffer tank 36, and are connected to a fuel pump (not shown) of the engine 12 and further to an injection device (a fuel injection device (not shown)) via a switching mechanism 28. The heavy fuel oil tank 30 , A tank containing heavy fuel oil to be supplied to the engine 12, the amount of heavy fuel oil required for at least one test, preferably
In order to confirm the repeatability of the evaluation result, a tank having a capacity capable of storing heavy fuel oil to be subjected to the test three to four times is used. The heavy fuel oil tank 30 is provided with a stirrer, and stirs the heavy fuel oil so that its properties become uniform.
In addition, a heater is provided to prevent fluidity deterioration.
The heavy fuel oil is heated to ５０50 ° C., and is further kept warm by a heat insulating material. The type and model of the stirrer and the heater are not limited as long as the above-mentioned object can be achieved. For example, as a heater, a heat transfer tube through which steam flows is provided inside the tank or along the outer wall of the tank. The temperature of heavy fuel oil is 30-50
C is preferred. If the temperature of the heavy fuel oil is lower than 30 ° C., the fluidity decreases and it becomes difficult to maintain uniform properties,
If the temperature is higher than 50 ° C., the properties may be deteriorated.

The intermediate tank 32 is provided with means for raising the temperature of the heavy fuel oil, and the heavy fuel oil is stably supplied by the injection device of the engine 12 to the combustion chamber (not shown) of the engine 12.
It is a tank that raises the temperature of heavy fuel oil to a temperature that can be sprayed inside. Any intermediate tank may be used as long as it can raise and maintain the heavy fuel oil to a predetermined temperature.
As a heating means, a stirrer for heavy fuel oil and a heater are provided. In the intermediate tank 4, heavy fuel oil
Heat to 2 ° C. If the temperature is low, the fluidity of the heavy fuel oil decreases, and it becomes difficult to stably spray the fuel into the combustion chamber by the injection device, and if the temperature is high, the properties are apt to deteriorate.

Fuel consumption meter (hereinafter referred to as fuel efficiency meter) 34
Is an instrument that continuously measures the flow rate of the heavy fuel oil and outputs the measurement result to the controller 26. The accuracy is ± in the entire flow rate range of 0.3 to 120 l / h.
Generally used ones can be used as long as they can withstand a fuel temperature from room temperature to 100 ° C. at 0.2%. Examples of the fuel economy meter 34 include a piston type capacity or weight integrated flow meter, an oval type capacity or weight integrated flow meter, and the like.

The buffer tank 36 is a tank provided to maintain the fluidity of the heavy fuel oil and to suppress the pulsation of the heavy fuel oil when injecting the fuel into the engine. Means for maintaining the temperature of the heavy fuel oil at 68-72 ° C. Here, the pulsation is a pressure fluctuation of the heavy fuel oil accompanying the fuel injection of the engine. In the present apparatus 10, since the heat input is obtained from the measured value of the heavy fuel oil flow rate of the fuel economy meter 34 to control the operation of the engine, an accurate flow rate measurement value is required. Therefore, a buffer tank 36 is provided in order to suppress the pulsation of the heavy fuel oil and to prevent the accuracy of the measured value from deteriorating due to the pulsation. The buffer tank 36 is a tank having a capacity capable of suppressing the pulsation of the heavy fuel oil to such an extent that the pulsation of the heavy fuel oil is not affected by the measurement of the fuel consumption meter 34. It is provided downstream of the total 34.
In particular, a single-cylinder engine tends to generate pulsation, so that it is necessary to use a large-capacity engine.

The light oil supply line 20 includes a light oil tank 38
When the engine is started, light oil is supplied from the light oil tank 38 to the engine 12 via the switching mechanism 28 in order to warm up the engine to a temperature at which heavy fuel oil can be sprayed by the injection device. The switching mechanism 28 connects the light oil supply system 20 and the heavy fuel oil supply system 18 downstream of the buffer tank 36, and switches between heavy fuel oil and light oil by operating a valve.

The piping connecting each component of the heavy fuel oil supply system 18 is preferably coated with a heat insulating material so that the temperature of the heavy fuel oil does not decrease during the oil supply and the fluidity does not decrease. It is traced by a heater tube such as a steam trace tube. Further, it is preferable to arrange each device so that the length of the pipe from the intermediate tank 32 to the injection device is reduced. This is because if the pipe is long, the heavy fuel oil is maintained at a relatively high temperature of 68 to 72 ° C., so that the heavy fuel oil is apt to deteriorate.

Further, in order to remove foreign matter from the heavy fuel oil, it is preferable to provide a fuel filter (not shown) upstream of the engine 12, for example, in front of the fuel consumption meter 34. The mesh size of the filter is 5
30 mesh, preferably about 10 mesh.
If it is less than 5 mesh, fine foreign matter cannot be sufficiently removed.
If the mesh size is 30 mesh or more, there is a possibility of removing the residual carbon content in the fuel.

The intake system 22 includes a compressor 40, an intake control valve 42, and an intake regulator 44.
The air for combustion is supplied to the engine 2 and the intake air temperature, the intake humidity and the excess air ratio of the supply air in the engine 12 are controlled to be constant under the control of the controller 26. The compressor 40 pressurizes an amount of air necessary to operate the engine 12,
The type of air compressor to be supplied is not limited as long as air can be supplied at a substantially constant pressure. As a compressor, at a pressure of 1317 to 1621 hPa, 2 m ³ / min to 1
For example, a roots blower capable of supplying 0 m ³ / min of fresh air is used. The intake control valve 42 is a valve that controls the excess air ratio by adjusting the intake pressure, and may be a manual valve or an automatic valve such as a butterfly valve, a ball valve, or a gate valve. The intake control valve 42 has an excess air ratio of 1.30 to
Accuracy ± 0.02 in the range of 1.60, preferably 1.60.
It can be automatically controlled to 40 ± 0.02. here,
The excess air ratio is the ratio of the actual air-fuel ratio to the stoichiometric amount of air required to completely burn the fuel. If the excess air ratio is low, stable combustion cannot be maintained,
If it is high, the difference in piston cleanliness depending on the type of lubricating oil cannot be clearly identified, so in the present invention, the excess air ratio is controlled to a predetermined value. The intake air regulator 44 includes an air heating / cooling unit and an air humidifying / dehumidifying unit, and is provided to adjust the temperature and humidity of the intake air to a constant level so that fluctuations in the outside air do not affect the test results. I have. The type and type of the intake air regulator 44 are not limited as long as the absolute humidity of the intake air can be adjusted to 10 ± 2 g / kg and the intake air temperature can be adjusted to ± 3 ° C. within the range of 30 to 130 ° C. In addition, the pipe of the intake system 22 has a pipe diameter corresponding to the intake air flow rate, and has a large radius of curvature at a bent portion so as not to cause a pressure loss.

The exhaust system 24 is provided with an exhaust control valve 46 for exhausting the engine 12 at a predetermined exhaust pressure and maintaining the combustion state of the engine 12 constant. The exhaust control valve 46 controls the exhaust pressure from 66 to
As long as the accuracy can be adjusted within a range of 470 hPa to ± 7 hPa, a commonly used one may be used, and examples thereof include a manual or automatic valve such as a butterfly valve, a ball valve, and a gate valve. . Also, the exhaust system 2
The pipe No. 4 has a pipe diameter commensurate with the flow rate of the exhaust gas, and has a large radius of curvature at the bend so as not to cause pressure loss.

The controller 26 controls the factors affecting the cleanliness of the pistons, that is, the amount of heat input to the engine 12, the engine speed, the excess air ratio, the temperature of the engine lubricating oil, the temperature of the engine coolant, and the exhaust pressure. It is provided to maintain the operating state of the engine at a predetermined state.

The controller 26 adjusts the throttle opening of the injection device to ± 1% and the engine speed to ± 10%.
rpm / min, the degree of opening of the intake control valve 42 is controlled by ± 0.02 in excess air ratio, the oil temperature of the engine is controlled by ± 2 ° C, and the degree of opening of the exhaust control valve 46 is controlled by exhaust pressure ± 7 hPa. I do. These control accuracies are necessary for improving the reproducibility and repeatability of the engine test. The controller may be a commonly used controller as long as it can achieve this purpose.

The controller 26 obtains the measured value of the engine speed from the engine 12 and, based on the measured value,
2 to set a heat input amount capable of maintaining the engine speed at a predetermined value, further obtain a flow rate measurement value from the fuel economy meter 34, calculate the heat input amount based thereon, and adjust the throttle opening of the injection device of the engine 12. In this way, the heat input is controlled to a predetermined value, whereby the rotational state of the engine is feedback-controlled. For example, when the amount of heat input is large and the engine speed is high, the throttle opening is reduced, and the amount of heat input is reduced to lower the engine speed. When the heat input is small and the engine speed is low, the throttle opening is increased to increase the engine speed.

The controller 26 obtains the measured value of the intake air amount of the engine 12, and adjusts the intake control valve 42 based on the measured value so as to maintain the excess air ratio at the set value. For example, when the excess air ratio is high, the excess air ratio is reduced by decreasing the opening of the intake control valve 42, and when it is low, the excess air ratio is increased by increasing the opening of the intake control valve 42. Also, the controller 26
Obtains a measured value of the exhaust pressure and adjusts the exhaust control valve 46 based on the measured value to control the exhaust pressure to a set value. For example, when the exhaust pressure is high, the opening of the exhaust control valve 46 is increased to decrease the exhaust pressure, and when the exhaust pressure is low, the opening of the exhaust control valve 46 is decreased to increase the exhaust pressure. Further, the controller 26 obtains the measured values of the oil temperature of the lubricating oil and the liquid temperature of the cooling liquid from the engine 12, and adjusts the heating / cooling means of the engine 12 based on the measured values, thereby obtaining the oil temperature of the lubricating oil and the liquid temperature of the cooling water. The temperature is controlled to a predetermined value.
In particular, the heat input, engine speed and excess air ratio greatly affect the cleanliness of the piston, and these fluctuations are the main factors in the dispersion of test results. There is a need to.

Test Method According to the Present Invention Hereinafter, a method according to the present invention for evaluating the cleanliness of a piston of a lubricating oil using the above-described test apparatus will be described. First, each test condition of the test method of the present invention is determined based on the following criteria. 1. 1. Hydraulic jet The hydraulic jet is for injecting lubricating oil to cool the piston, and has a pressure capable of injecting at least the minimum amount of lubricating oil required to prevent scuffing. Fuel temperature Fuel temperature is a temperature that does not harden or alter heavy fuel oil during oil transfer.
The temperature is set so that fuel spray can be stably performed in the combustion chamber of the engine. 3. Fuel pressure The fuel pressure is set to a value that can supply sufficient fuel to the engine and does not adversely affect the spraying of the injection device. 4. Excess air ratio The excess air ratio is an excess air ratio that supplies a quantity of air that can maintain stable combustion and clarify the difference in piston cleanliness depending on the type of lubricating oil. If the excess air ratio is too low, stable combustion cannot be maintained, and if it is too high, a difference in piston cleanliness between oil types cannot be obtained. 5. Lubricating oil amount The lubricating oil amount is the minimum amount that can supply lubricating oil to the engine according to the amount of lubricating oil consumed. 6. Injection timing The injection timing is adjusted so that the same output as that of light oil can be obtained with heavy fuel oil at the same heat input. Thus, it is possible to prevent abnormal combustion due to a difference in fuel oil. 7. Engine speed The engine speed should be within the range that does not cause engine problems such as scuffing, and is adjusted according to the performance of the sample lubricant. When the engine speed is increased, the degree of severeness with respect to piston cleanliness is increased, and the difference in piston cleanliness between high-performance lubricating oil types becomes remarkable. 8. Oil temperature / water temperature Oil temperature / water temperature shall be within the range where engine problems such as scuffing do not occur, and adjusted according to the performance of the sample lubricating oil.
Increasing the oil / water temperature increases the cylinder liner temperature, increases the severity of piston cleanliness, and makes the difference in piston cleanliness between high-performance lubricating oil types remarkable. 9. Coolant Generally, water, ethylene glycol, or a mixture thereof is used as the coolant.However, when it is necessary to increase the severity, a coolant having a low specific heat, such as triethylene glycol, is used to cool the engine. Reduces heat release and raises cylinder liner temperature. 10. Heat input The heat input shall be the minimum amount that can provide the required severity. This is because increasing the heat input increases the engine speed and increases the severity.However, in the piston cleanliness test, the difference in fuel properties greatly affects the test results. This is because it is desirable to be able to perform the test.

Evaluation of the cleanliness of the piston of the lubricating oil after the engine test is based on the land diesel engine piston evaluation method JP
Performed according to I-5S-15-94, TGF, WT
D. Lubricating oil based on the amount of carbon deposited on the piston underside (hereinafter simply referred to as the underside), the average amount of carbon deposited on the ring group, the average amount of carbon deposited on the ring land, the degree of liner wear, the degree of ring wear, and the presence or absence of scuffing To evaluate the cleanliness of the piston. TGF (To
p Groove Fill is a carbon clogging volume% of the first ring groove and is a number of 0 to 100% obtained by TGF = Σ (carbon adhesion area × cutting coefficient) / 10, and the smaller the value, the higher the piston cleanliness. WTD (Weight
ed Total Demerits) means 2 to 4 piston lands, 1
The total score of carbon and lacquer deposited on the ring grooves of the pistons of ４4 ring grooves, indicated by a number between 0 and 16959. The smaller the value, the higher the piston cleanliness. The underside is obtained by evaluating the amount of carbon deposited on the back side of the piston (the side opposite to the combustion chamber of the engine) from 0 to 10 points.
The point is the best, and 0 is the worst. The sticking of the piston ring is obtained by extracting the piston from the engine and evaluating the degree of movement of the piston ring.

[0028]

The embodiments of the present invention will be described below in detail with reference to examples. The present invention is not limited by these examples. Test Apparatus In this example, an engine and a buffer tank having the following specifications were used as the engine 12 and the buffer tank 36 of the test apparatus 10. Number of engines cylinders: single cylinder total engine: 2200 cm ³ buffer tank capacity: 9400Cm ³

Engine Fuel In this embodiment, fuel oil having the following properties was used as engine fuel. Heavy fuel oil (C heavy oil corresponding to three kinds of JIS K2205) Density (15 ° C.): 0.966 g / cm ³ Kinematic viscosity (50 ° C.): 175 mm ² / s Residual carbon content: 9.27 mass% Sulfur content: 2.47 mass% light oil (equivalent to JIS K2204) Density (15 ° C): 0.847 g / cm ³ Kinematic viscosity (30 ° C): 4.488 mm ² / s Residual carbon content: 0.01 mass% or less Sulfur content: 0 .18 mass%

Preliminary Test In performing an engine test of the sample lubricating oil, a preliminary test was performed under conditions 1 to 16 set within the following test conditions, and the injection timing, engine speed, heat input, oil temperature, and liquid temperature were measured. And the type of cooling liquid was examined and each was established. Less than,
The preliminary test will be described. First, the engine was started using light oil as fuel and operated at an engine speed of 1400 rpm. After both the coolant temperature and the lubricating oil temperature reached 70 ° C., the fuel was switched from light oil to heavy fuel oil. Was.

Test conditions Engine speed (r / min): 1400-1600 Heat input (kJ / min): 5516-6229 Lubricating oil temperature (° C): 95-105 Hydraulic jet (kPa): 178 or more Cooling water outlet temperature (° C): 90-105 Fuel temperature (° C): 60-80 Fuel pressure (kPa): 49-245 Intake pressure (kPa): 166 Excess air ratio (-): 1.3-1.6 Injection timing: Compression 15 ° before top dead center Lubricating oil amount (liter): 4.5 Test time (h): 100 Ethylene glycol-water or triethylene glycol-water system as a cooling liquid, ethylene glycol and triethylene glycol concentrations of 85% Use １００100%.

Setting of Injection Timing Since the test apparatus 10 uses a diesel engine using light oil as fuel, when testing using heavy fuel oil as fuel, the heat input is the same as that of light oil. Even if it is set to a different value, the output will differ due to the difference in combustion speed between light oil and heavy fuel oil. For this reason, it is necessary to adjust the injection timing of the heavy fuel oil so that the same output as when light oil is used as fuel is obtained. Therefore, the injection timing is set to 15 ° before compression top dead center.
When the heat input was 6176 kJ / min for both the case where
With respect to the case of 246 kJ / min, a load test was performed under the conditions 1 to 6 shown in Table 1, and the results shown in Table 1 were obtained. When the heat input is 6176 kJ / min, the same output as the condition 1 is obtained under the condition 3 different in fuel, and the heat input is 5246 kJ / min.
In the case of the condition (2), the same output as the condition (4) can be obtained in the condition (6) where the fuel is different. From this, when using heavy fuel oil as fuel, to obtain the same output as with light oil,
It was found that the injection timing should be set to 15 ° before the compression top dead center.

[Table 1]

Setting the engine speed When the engine speed is high, the severity of the cleanliness of the piston increases, but there is a problem that scuffing occurs. Therefore, as long as problems such as scuffing that damages the engine do not occur, it is better to set the engine speed higher, and the difference in piston cleanliness between the oil types of the sample lubricant becomes remarkable. In particular, the piston cleanliness of high performance lubricating oil can be clearly evaluated. Therefore, in the present embodiment, as shown in conditions 7 to 11 in Table 2, the engine speed was set to 1800 rpm, 1500 rpm, and 1200 rpm, and the presence or absence of scuffing was tested, and the results shown in Table 2 were obtained. Table 2 shows that scuffing does not occur under the conditions 9, 10 and 11 where the engine speed is 1500 rpm or less.
At 800 rpm, scuffing occurred. Therefore, the engine speed is set to 1500 rpm.

[Table 2]

Setting of Kind of Coolant, Oil Temperature of Lubricating Oil and Water Temperature of Coolant In engine tests, increasing the cylinder liner temperature, and hence the oil temperature of the lubricating oil and the temperature of the coolant, increases piston cleanliness. The severity increases and the difference in piston cleanliness between the test oils becomes significant. Particularly, in the case of a high-performance lubricating oil, it is desirable to set the temperature to a high temperature. Therefore, in the present embodiment, in order to raise the oil temperature of the lubricating oil and the liquid temperature of the cooling liquid to the extent that the engine damage problem such as scuffing does not occur, the types of the cooling liquid are set under the conditions 12 to 16 shown in Table 3. ,
The cylinder liner temperature was measured while changing the oil temperature and the coolant temperature, and the results shown in Table 3 were obtained.

[Table 3]

Setting of Test Conditions From Table 3, it was found that under the condition 12, the cylinder liner temperature was low and the severity was low for evaluating the marine system cylinder oil. Conditions 13 to 16 are the temperature levels required to evaluate the marine system cylinder oil. Among them, the condition 15 in which triethylene glycol is used as the coolant is a condition under which there is no scuffing and ring sticking, the heat input is small, the cylinder liner temperature is the highest, and therefore the piston cleanliness is the most severe. Therefore, it was determined that the test conditions were optimal.
Therefore, in the present embodiment, the condition 15 is set as a test condition of the evaluation test of the piston cleanliness.

[0036] was carried out piston cleanliness test from the test No. 1 to 8 by the method of the present invention under the conditions of the conditions 15 obtained in piston cleanliness test preliminary test according to the method of the present invention. (1) Evaluation by Oil Grade In Test Nos. 1 to 4, lubricating oil No. 30 having the same viscosity grade but different base number and dispersant amount was tested under condition 15, and the results shown in Table 4 were obtained. From Table 4, in the same dispersion type, higher base number oil shows higher piston cleanliness,
It was found that a remarkable difference was obtained between the oil types of the sample lubricating oil. Therefore, it is understood that the method of the present invention can clearly evaluate the piston cleanliness of a lubricating oil in which the viscosity grade is the same and only the base number and the dispersant amount are different. Can be evaluated.

[Table 4]

(2) Repetition test In order to confirm the reproducibility of the method of the present invention, test numbers 5 to 8 were used.
Then, the same type of lubricating oil was repeatedly subjected to the same piston cleanliness test under the same conditions 15, and the results shown in Table 5 were obtained. From Table 5, it can be determined that the method of the present invention can perform highly reproducible evaluation of piston cleanliness.

[Table 5]

Comparison between the test according to the method of the present invention and the actual machine test (1) Comparison with the actual machine test using a land-based in-house power generation system According to the test, the engine output was 5800 kW and the engine oil amount was 8
On-land private power generation system with KL engine 5
An actual machine test for 000 to 6000 hours was performed and compared with the evaluation by the method of the present invention. The results are as shown in Table 6. In Table 6 and Table 7 below, P means pentane-insoluble matter (% by mass), and AP means aggregated pentane-insoluble matter (% by mass). From Table 6, the lubricating oil which showed good piston cleanliness by the method of the present invention was 6000 in the on-land private power generation system.
Even after use for a long time, good piston cleanliness was shown.

[Table 6]

(2) Test by Ferries For the cleanliness of pistons of the same lubricating oil, a two-year actual test was conducted using ferries with an engine output of 9700 kW × 2 units and an engine oil amount of 5 KL in accordance with the test by the method of the present invention. And the evaluation by the method of the present invention. The results are as shown in Table 7. From Table 7, it can be seen that the lubricating oil which showed good piston cleanliness by the method of the present invention showed good piston cleanliness even when used on a ferry for 2 years.

[Table 7]

From the comparison with the above-mentioned actual machine test, the method of the present invention has a high reliability regarding the cleanliness of the piston, and can easily perform the evaluation having a high correlation with the actual machine test in a short time.

[0041]

According to the present invention, a commercially available diesel engine using gas oil as fuel is used, and the diesel engine is subjected to severe operating conditions, particularly engine speed, coolant temperature and lubricating oil temperature. By operating under such conditions and strictly controlling the amount of heat input and the excess air ratio, it is possible to quickly and reliably evaluate the cleanliness of the piston of the lubricating oil. Even if performance lubricating oils are used, the performance difference can be clearly identified. Further, the results of the piston cleanliness test according to the method of the present invention have extremely high reproducibility and have a high correlation with the results of the test using an actual machine. Therefore, by using the method of the present invention, the bench scale test method, which was conventionally technically difficult,
Piston cleanliness of marine lubricating oil can be easily and objectively evaluated with high reliability. The test apparatus according to the present invention uses a small diesel engine that uses commercially available light oil as fuel compared to the engine of an actual ship, so the equipment cost and operation cost of the apparatus are low, and the piston cleaning of marine lubricating oil is performed. Sex can be evaluated economically.

[Brief description of the drawings]

FIG. 1 shows a configuration diagram of an example of a marine lubricating oil cleanliness test apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 10 piston cleanliness test apparatus according to the present invention 12 engine 14 dynamometer 16 apparatus main body 18 heavy fuel oil supply system 20 light oil supply system 22 intake system 24 exhaust system 26 controller 28 switching mechanism 30 heavy fuel oil tank 32 heavy fuel Oil intermediate tank 34 Fuel consumption meter (fuel consumption meter) 36 Buffer tank 38 Light oil tank 40 Compressor, roots blower 42 Intake control valve 44 Intake regulator 46 Exhaust control valve

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hiromichi Ikebe 1134-2 Gondogendo, Satte City, Saitama Prefecture Inside the R & D Center, Kosmo Research Institute, Inc. (72) Inventor Takashi Nishio 1134-2 Gongendo, Satte City, Saitama Prefecture Cosmo Research Institute R & D Center

Claims (5)

[Claims] 1. A test apparatus main body having a light oil combustion type diesel engine capable of freely adjusting a fuel injection amount, an oil temperature of lubricating oil, and a liquid temperature of a coolant, a dynamometer for applying a load to the diesel engine, and a diesel engine. A heavy fuel oil supply system that supplies heavy fuel oil to the diesel engine, an intake system with an adjustable excess air ratio that supplies combustion air to the diesel engine, an engine speed of the diesel engine under a predetermined load,
A control device for controlling the oil temperature of the lubricating oil and the liquid temperature of the cooling fluid to predetermined values, respectively. 2. The piston cleanliness test apparatus according to claim 1, further comprising a light oil supply system for supplying light oil to the diesel engine, and a mechanism for switching between light oil and heavy fuel oil. 3. The apparatus for testing cleanliness of a marine lubricating oil piston according to claim 1, further comprising an exhaust system for exhausting the diesel engine with an adjustable exhaust pressure. 4. A test method for evaluating the cleanliness of a piston of a marine lubricating oil using the test apparatus according to claim 1, wherein a heavy fuel oil is used as a fuel. A preliminary test is performed in advance, and at least the engine speed, the lubricating oil temperature, and the coolant temperature among the factors that affect the cleanliness of the piston can be set within limits that do not cause engine damage including scuffing. Setting a high speed and high temperature only, and using a heavy fuel oil as a fuel under the set engine speed, oil temperature and liquid temperature conditions, using a sample lubricating oil to run the diesel engine for a predetermined time. Operating a lubricating oil for marine use, comprising: evaluating a piston cleanliness according to a known land diesel engine piston cleanliness evaluation standard. Piston cleanliness test method. 5. The method for testing the cleanliness of a marine lubricating oil piston according to claim 4, wherein the test apparatus according to claim 2 is used to perform a warm-up operation with light oil when the engine is started.