JP2023084792A - Friction test device - Google Patents

Abstract

To enable grasping the optimum blending ratio of an additive agent added to lubrication oil in a small testing number.SOLUTION: A circulation pump 40 circulates lubrication oil 100 in a circulation flow channel 70. A syringe pump 20 continuously injects an additive agent 110 that changes a friction performance to the lubrication oil 100 in the circulation flow channel 70 in a constant injection amount per a unit time. A static mixer 30 agitates the lubrication oil 100 in the circulation channel 70 after the additive agent 110 is injected by the syringe pump 20. An oil tank 50 stores the lubrication oil 100 circulating in the circulation flow channel 70. A friction coefficient measurement machine 60 measures a change in a friction coefficient according to the time course from the injection start of the additive agent 110 by the syringe pump 20 by using the lubrication oil 100 stored in the oil tank 50.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a friction test apparatus for grasping the mixing ratio of additives added to lubricating oil.

PAO (Poly-Alpha-Olefins), which is a hydrocarbon-based synthetic lubricating oil, is used as a lubricating oil for various devices. It is known to add an additive such as oleic acid to such a lubricating oil to reduce the coefficient of friction and improve the friction performance.

Since additives are often more expensive than lubricating oils, the mixing ratio of additives added to lubricating oils should be kept to a minimum. However, if the blending ratio of the additive to be added is too low, good friction performance may not be obtained. Moreover, if the additive is added more than necessary, the coefficient of friction may rather increase. Therefore, there is an optimum range for the mixing ratio of the additive added to the lubricating oil.

However, there are various types of lubricating oils and additives, and the optimum mixing ratio must be determined for each combination of lubricating oils and additives.

For example, in US Pat. No. 6,200,000, a system condition parameter is directly or indirectly measured in a system in which a base lubricating oil is injected with a performance enhancer as a second fluid and then stirred and recirculated, and the measured A system is disclosed for calculating from system parameters the amount of secondary fluid to be added to the base lubricant.

Japanese Patent Publication No. 2005-518494

The system disclosed in the above-mentioned Patent Document 1 attempts to adjust the amount of the second fluid to be added to the base lubricating oil under actual engine operating conditions. A specific method of how to calculate the amount of is not disclosed. Therefore, in the system disclosed in Patent Document 1, the amount of the second fluid to be added to the base lubricating oil is varied in order to obtain the optimum mixing ratio of the second fluid to be mixed with the base lubricating oil. There is a need.

In this way, conventionally, when determining the optimum blending ratio of an additive to a lubricating oil, a plurality of test oils in which additives are added to the lubricating oil at different blending ratios are prepared in advance, and each test oil Friction tests were conducted on these materials, and the optimum mixing ratio was determined based on the test results. However, when a friction test is performed, it is necessary to repeatedly perform a plurality of tests on one test oil because the test results contain repeatable errors. Moreover, in the friction test, various errors may occur as the number of tests increases due to the state of wear of the test pieces, variations in the test pieces, contact between the test pieces, and the like. Therefore, even in order to determine the optimum blending ratio in one set of lubricating oil and additive combination, the number of friction tests obtained by multiplying the number of test oils with different blending ratios by the number of repeated tests is required. It is a factor that increases the development period and development cost of the product.

SUMMARY OF THE INVENTION An object of the present invention is to provide a friction test apparatus capable of ascertaining the optimum mixing ratio of additives to be added to a lubricating oil with a small number of tests.

The friction test device of the present invention includes a circulation pump that circulates lubricating oil in a circulation channel,
an injection mechanism that continuously injects an additive that changes friction performance into the lubricating oil in the circulation channel at a constant injection amount per unit time;
a stirring unit that stirs the lubricating oil after the additive has been injected by the injection mechanism in the circulation flow path;
an oil tank for storing lubricating oil circulating in the circulation flow path;
a measuring unit that continuously measures changes in the coefficient of friction with the lapse of time from the start of injection of the additive by the injection mechanism, using the lubricating oil stored in the oil tank.

In the present invention, in a state in which the lubricating oil is circulated in the circulation channel by the circulation pump, the additive is continuously injected by the injection mechanism at a constant injection amount per time, and the lubricating oil into which the additive is injected is injected. The oil is stirred by the stirrer, and the friction test is continuously performed by the measuring part in the oil tank to record the change of the friction coefficient. Therefore, according to the present invention, it is possible to grasp the optimum mixing ratio of the additive to the lubricating oil from the elapsed time from the start of the test and the recorded change in the friction coefficient.

Further, in another aspect of the friction test apparatus of the present invention, the injection mechanism is configured such that the additive is continuously injected into the lubricating oil at a constant injection amount per unit time by pushing out the additive stored in the syringe with a plunger. A syringe pump for direct injection may be used.

The syringe pump is suitable for injecting a small amount of liquid at a constant injection amount per unit time, and according to this aspect of the present invention, the additive can be accurately injected into the lubricant at a constant injection amount. becomes possible.

Further, in another aspect of the friction test apparatus of the present invention, the injection mechanism contains an additive having a volume of 1/10000 or more and 1/100 or less of the total volume of the lubricating oil circulating in the circulation flow path. It may be configured so that it can be injected every minute.

Furthermore, in another aspect of the friction test apparatus of the present invention, the measuring unit is installed in the oil tank, and is a rotary type that measures the coefficient of friction by bringing a contactor to which a load is applied onto a rotating disc-shaped sample into contact. may be used as a friction coefficient measuring machine.

A rotary friction coefficient measuring instrument is more suitable for continuously measuring the friction coefficient than a reciprocating one. It is possible to continuously and accurately measure changes in the coefficient of friction.

In another aspect of the friction test apparatus of the present invention, a filter for removing metal powder contained in lubricating oil flowing from the oil tank into the circulation flow path may be further provided.

According to this aspect of the present invention, it is possible to prevent metal powder generated when continuously measuring changes in the friction coefficient in the measuring unit from being removed by the filter and circulating in the circulation flow path, It is possible to improve the accuracy of the measured coefficient of friction.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to grasp|ascertain the optimal compounding ratio of the additive added to lubricating oil by few tests.

It is a figure showing composition of friction test equipment 10 of one embodiment of the present invention. It is a figure which shows the structure of the syringe pump 20 shown in FIG. 2 is a diagram showing the structure of static mixer 30 shown in FIG. 1. FIG. FIG. 2 is a diagram showing the structure of the friction coefficient measuring device 60 shown in FIG. 1; It is a figure which shows the test conditions in the friction test apparatus 10 of one Embodiment of this invention. FIG. 6 is a diagram showing a graph of test results based on the test conditions shown in FIG. 5; 4 is a diagram showing a graph of friction test results according to Comparative Example 1. FIG. 8A is a diagram showing the blending ratio of the test oil used in Comparative Example 2 (FIG. 8A), and a graph showing the test results of the friction test in Comparative Example 2 (FIG. 8B).

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall view showing the configuration of a friction test apparatus 10 according to one embodiment of the present invention.

As shown in FIG. 1, the friction test apparatus 10 of the present embodiment includes a syringe pump 20 as an injection mechanism, a static mixer 30 as a stirring unit, and a It has a configuration in which a circulation pump 40 and an oil tank 50 are provided. A friction coefficient measuring device 60 is installed in the oil tank 50 to perform a friction test using the lubricating oil 100 and measure the friction coefficient.

In the friction test apparatus 10 of the present embodiment, the lubricating oil 100 circulates in the circulation channel 70, which is a closed channel, and the optimum mixing ratio of the additive 110 to the lubricating oil 100 is determined. It is configured to perform a friction test with

In the present embodiment, the lubricating oil 100 is a PAO4 standard poly-α-olefin synthetic lubricating oil. Then, a case where oleic acid is added as additive 110 to lubricating oil 100 will be described. In addition, the combination of the lubricating oil 100 and the additive 110 is not limited to such a type of combination. The present invention is similarly applicable even when an agent is added. In addition, improving friction performance means reducing a coefficient of friction here.

Circulation pump 40 circulates lubricating oil 100 in circulation passage 70 . The circulating flow rate per minute of the circulating pump 40 is preferably about 1/10 to 10 times the total amount of the lubricating oil 100 circulating in the circulating flow path 70 . Here, in this embodiment, the case where the total amount (total volume) of the lubricating oil 100 circulating in the circulation flow path 70 is 40 ml will be described. That is, the circulation flow rate per minute of the circulation pump 40 is preferably about 4 ml to 400 ml. As the circulation pump 40 of the present embodiment, a pump having a circulation flow rate of 100 ml per minute is used.

Both the circulation pump 40 and the piping forming the circulation flow path 70 must have heat resistance according to the type of lubricating oil 100 used and the oil temperature to be measured.

The syringe pump 20 functions as an injection mechanism that continuously injects the additive 110 that changes the frictional performance into the lubricating oil 100 in the circulation passage 70 at a constant injection amount per unit time.

The syringe pump 20 continuously injects the additive 110 into the lubricating oil 100 at a constant injection amount per unit time by pushing out the additive 110 stored in the syringe with a plunger.

The syringe pump 20 is configured to be able to inject the additive 110 in a volume of 1/10000 or more and 1/100 or less of the total volume of the lubricating oil 100 circulating in the circulation passage 70 every minute. is preferred.

For example, in the present embodiment, as described above, the total amount (total volume) of the lubricating oil 100 circulating in the circulation flow path 70 is 40 ml. Those that can be controlled between 0.4 ml are suitable.

In addition, in this embodiment, the injection amount per minute of the syringe pump 20 is assumed to be 0.025 ml.

The maximum amount of additive to be injected from the syringe pump 20 into the lubricating oil 100 is preferably about 1/1000 to 1/10 of the total volume of the lubricating oil 100 . That is, in the present embodiment, since the total amount (total volume) of the lubricating oil 100 circulating in the circulation flow path 70 is 40 ml, the syringe pump 20 contains 0.04 to 4 ml of the additive 110 in advance. It is preferable to keep In this embodiment, it is assumed that 0.5 ml of the additive 110 is put into the syringe pump 20 in advance and the test is performed.

Static mixer 30 functions as a stirring unit that stirs lubricating oil 100 after additive 110 has been injected by syringe pump 20 in circulation flow path 70 .

The oil tank 50 stores the lubricating oil 100 circulating within the circulation flow path 70 . The oil tank 50 may be provided with a function of directly adjusting the temperature of the lubricating oil 100, or an oil tank having a temperature adjusting function may be provided separately. In addition, when an oil tank having a temperature control function is provided separately, the circulation flow rate per minute of the circulation pump 40 is about 1/10 to 10 times the total amount of the lubricating oil 100 circulating in the circulation flow path 70. It is necessary to determine the capacity of the oil tank 50 so that

The friction coefficient measuring device 60 uses the lubricating oil 100 stored in the oil tank 50, and is a measuring unit that continuously measures changes in the friction coefficient over time from the start of injection of the additive 110 by the syringe pump 20. function as

The friction coefficient measuring device 60 is installed in the oil tank 50, and measures the friction coefficient by contacting a contact such as a ball test piece to which a load is applied on a rotating disc test piece (disk-shaped sample). It is a coefficient measuring machine. A detailed configuration of the friction coefficient measuring device 60 will be described later.

The filter 80 is provided to remove metal powder contained in the lubricating oil 100 flowing into the circulation flow path 70 from the oil tank 50 . In the friction coefficient measuring machine 60, the disk test piece is rotated while the contactor such as the disk test piece and the ball test piece are in contact with each other, so that metal powder is generated. If this metal powder mixes with the lubricating oil 100 circulating in the circulation passage 70 , it may adversely affect the measurement of the friction coefficient by the friction coefficient measuring device 60 . Therefore, in the friction test apparatus 10 of the present embodiment, the filter 80 is installed at the outlet of the lubricating oil 100 of the oil tank 50 to prevent metal powder from entering the lubricating oil 100 and improve the measurement accuracy of the friction coefficient. I have to.

Next, FIG. 2 shows the structure of the syringe pump 20 shown in FIG.

As shown in FIG. 2, the syringe pump 20 includes a syringe (outer cylinder) 22 in which an additive 110 is enclosed, a plunger (inner cylinder) 23, and a motor 21 such as a stepping motor. The plunger 23 is configured to be pushed by rotation.
In the syringe pump 20, when the plunger 23 is pushed, the additive 110 enclosed in the syringe 22 is pushed out from the cylinder tip.

By being configured as described above, the syringe pump 20 functions as an injection mechanism that continuously injects the additive 110 into the lubricating oil 100 in the circulation flow path 70 at a constant injection amount per unit time. .

Next, FIG. 3 shows the structure of the static mixer 30 shown in FIG.

The static mixer 30 is configured to efficiently mix and stir the lubricating oil 100 circulating in the circulation channel 70 by the shape of the channel. For example, a static mixer manufactured by Noritake Co., Ltd. can be used. . Specifically, the static mixer 30 has a configuration in which a plurality of stirring elements 31 and 32 are alternately arranged within a pipe. The stirring elements 31 and 32 are each shaped like a rectangular plate twisted 180 degrees, with the stirring element 31 twisted rightward and the stirring element 32 twisted leftward. . By alternately arranging the plurality of stirring elements 31 and 32 having different twist directions, the lubricating oil 100 flowing in the static mixer 30 is divided, converted, and reversed by the arranged stirring elements 31 and 32. turbulent agitation. 1 and 3 show a case where two stirring elements 31 and 32 are arranged in order to simplify the explanation, but actually more stirring elements 31 and 32 are shown. are placed respectively.

Since static mixer 30 is configured in this manner, additive 110 injected into circulation flow path 70 by syringe pump 20 is quickly mixed with lubricating oil 100 by static mixer 30 .

In addition, it is necessary to select the static mixer 30 having specifications suitable for the flow rate determined according to the total flow rate of the lubricating oil 100 circulating in the circulation passage 70 .

Next, FIG. 4 shows the structure of the friction coefficient measuring machine 60 shown in FIG.

As the friction coefficient measuring device 60, various types of measuring devices can be used, but a rotating type is preferable because the friction coefficient can be measured continuously. In particular, a ball-on-disk type rotary friction coefficient measuring machine can be preferably used because the test piece is less likely to come into contact with one side.

As shown in FIG. 4, the friction coefficient measuring machine 60 in this embodiment has a ball test piece 62 attached to the tip of an arm 63, and the ball test piece 62 to which a load is applied is brought into contact with a rotating disk test piece 61. It is configured to measure the coefficient of friction.

As the disc test piece 61, for example, a disc made of SUJ2 having a diameter of 60 mm and a thickness of 5 mm is used. As the ball test piece 62, for example, a metal ball made of SUJ2 with a diameter of 5 mm is used.

In order to measure the coefficient of friction with higher accuracy, it is particularly preferable to use a three-ball type upper test piece and a gimbal mechanism provided in the retainer of the lower disk test piece.

In addition, in order to stably measure the coefficient of friction, it is desirable to perform a break-in test before injecting the additive 110 into the lubricating oil 100 . Depending on the test piece and conditions used, it is preferable to start injecting the additive 110 into the lubricating oil 100 after performing a break-in test for at least 10 minutes as the time until the friction coefficient stabilizes.

In the friction test apparatus 10 of the present embodiment, the lubricant 100 is circulated in the circulation channel 70 by the circulation pump 40, and the additive 110 is continuously injected by the syringe pump 20 at a constant injection amount per hour. Then, the lubricating oil 100 into which the additive 110 is injected is stirred by the static mixer 30, and the friction test is continuously performed by the friction coefficient measuring device 60 in the oil tank 50 to record the change of the friction coefficient. Therefore, according to the friction test apparatus 10 of the present embodiment, it is possible to grasp the optimum mixing ratio of the additive 110 to the lubricating oil 100 from the elapsed time from the start of the test and the recorded change in the friction coefficient. .

Next, actual test results by the friction test apparatus 10 of this embodiment will be described.

FIG. 5 shows the test conditions in the friction test apparatus 10 of this embodiment. The test conditions shown in FIG. 5 also include the test conditions already explained above.

First, the test was conducted by setting the load when pressing the ball test piece 62 against the disk test piece 61 in the friction coefficient measuring machine 60 to 50 N (initial maximum hertz pressure 2.7 GPa (pascal). Further, the disk test The rotation speed of the piece 61 was set to 60 rpm, and the radius of rotation of the circular orbit along which the ball test piece 62 moved on the disk test piece 61 was set to 10 mm.In other words, the sliding speed was 62.8 mm/sec. The temperature was room temperature and the break-in time was 10 minutes.As described above, the circulation flow rate of the circulation pump 40 was 100 ml/min, and the injection rate of the additive 110 in the syringe pump 20 was 0.025 ml/min. As the oil 100, SpectraSyn4 of PAO4 standard manufactured by ExxonMobil was used.

A graph of test results based on the test conditions as described above is shown in FIG. FIG. 6 shows the results of two tests performed under the same conditions. Referring to FIG. 6, it can be seen that the change in the coefficient of friction from the start of the test is continuously shown graphically.

In this friction test, the injection of the additive 110 was started with the syringe pump 20 after a break-in time of 10 minutes (600 seconds). Referring to FIG. 6, in all test results, the friction coefficient decreased around 1020 seconds after the start of the measurement of the friction coefficient, and after 1200 seconds (600 seconds after the injection of additive 110), the value was stably low. It can be seen that

Then, the injection amount of the additive 110 injected into the lubricating oil 100 within 600 seconds after the injection of the additive 110 is started is calculated by the following formula.

Injection amount of additive 110 = injection speed x elapsed time from start of injection

Referring to the test result example shown in FIG. 6, the injection amount of the additive 110 is calculated as follows.

0.025 (ml/min) x 600 (seconds)/60 = 0.25 (ml)

From these test results, it can be seen that when adding the additive 110 to the lubricating oil 100, it is necessary to add 0.25 ml or more of the additive 110 to 40 ml of the lubricating oil 100. Although the absolute values of the friction coefficients differed in the two test results, there was no difference in the amount of the additive 110 required to reduce the friction coefficient. It turns out that there is no need to consider.

Even if the additive 110 is injected into the lubricating oil 100 by the syringe pump 20, the measurement result of the friction coefficient measuring device 60 does not change immediately, and a certain amount of time lag occurs. When determining the optimum blending ratio of additive 110 in consideration of such a time lag, the time taken for lubricating oil 100 circulating in circulation passage 70 to make at least one revolution may be taken into consideration.

For example, in the case of the present embodiment, the circulation flow rate per minute of the circulation pump 40 is 100 ml, and the total amount of the lubricating oil 100 circulating in the circulation flow path 70 is 40 ml. x60), the lubricating oil 100 makes one turn in the circulation flow path 70 . Therefore, when calculating the injection amount of the additive 110, the required blending amount of the additive 110 may be calculated by subtracting the time for the time lag from the elapsed time from the start of injection of the additive 110.

[Comparative Example 1]
Next, without using the syringe pump 20 and without stopping the circulation pump 40 to circulate the lubricating oil 100 in the circulation flow path 70, the additive 110 was added with a dropper after the break-in time of 10 minutes. As a comparative example, a case in which 0.025 m of oil is dropped every minute in the vicinity of the test location in the oil tank 50 will be described. FIG. 7 shows the friction test results of this comparative example. Test conditions other than those specifically mentioned are the same test conditions as the embodiments of the invention described above.

The test was conducted twice under the same conditions in Comparative Example 1 shown in FIG. Since it is not obtained, it can be seen that the additive 110 is not dissolved in the lubricating oil 100 .

[Comparative Example 2]
Next, without stopping the circulation pump 40 to circulate the lubricating oil 100 in the circulation flow path 70 and without injecting the additive 110 into the lubricating oil 100, a plurality of types of lubricating oil containing the additive 110 in advance are mixed. A case where a friction test was performed using Oil 100 as a test oil will be described as a comparative example. Also in this comparative example, the test conditions other than those specifically mentioned are the same test conditions as in the above-described embodiment of the present invention.

FIG. 8(A) shows the blending ratio of the test oil used in this comparative example. Referring to FIG. 8(A), the composition of a plurality of test oils 1 to 6 with different amounts of additive 110 blended with 40 ml of lubricating oil 100 is shown. In this comparative example, a 30-minute friction test was conducted using test oils with different blending ratios, and the friction coefficient was measured after 30 minutes. The test was performed three times for each test oil.

A graph of the test results of the friction test in this comparative example is shown in FIG. 8(B).

Looking at the average values of the three friction test results, it can be seen that test oil 3 showed a decrease in friction coefficient, and test oils 4, 5, and 6 showed stable low friction coefficients. From this test result, it can be seen that the required amount of additive 110 blended with 40 ml of lubricating oil 100 is between 0.2 ml and 0.3 ml.

This result is consistent with the decrease in friction coefficient when 0.25 ml of additive 110 was incorporated in one embodiment of the present invention described above, but the test results were obtained by conducting three tests under the same conditions. It can be seen that the same determination as in the embodiment of the present invention cannot be made unless the average value of . In one embodiment of the present invention, only two friction tests were required, but in this comparative example, it can be seen that the number of friction tests has increased significantly, requiring 18 friction tests.

Furthermore, in this comparative example, it was only found that there was an optimum blending ratio between 0.2 ml and 0.3 ml. Additionally, additional friction tests must be performed, further increasing the number of tests.

On the other hand, in the friction test apparatus 10 according to one embodiment of the present invention described above, the optimum blending ratio of the additive 110 can be grasped only by performing the friction test twice. It can be seen that the optimal mixing ratio of the additive 110 to be added to the lubricating oil 100 can be grasped with a small number of tests.

In addition, in the test results for the friction test device 10 of the embodiment of the present invention, the friction test was performed twice in order to ensure more accuracy. It is possible to grasp the optimum mixing ratio of the additive 110 to be added.

[Variation]
In the above embodiment, the lubricating oil 100 is PAO, and the additive 110 is oleic acid. The present invention can be similarly applied to the case of determining the optimum mixing ratio with additives.

10 friction test device 20 syringe pump 21 motor 22 syringe (outer cylinder)
23 plunger (inner cylinder)
30 Static Mixer 31, 32 Stirring Element 40 Circulation Pump 50 Oil Tank 60 Friction Coefficient Measuring Instrument 61 Disk Test Piece 62 Ball Test Piece 63 Arm 70 Circulation Channel 80 Filter 100 Lubricating Oil 110 Additive

Claims (5)

a circulation pump that circulates the lubricating oil in the circulation channel;
an injection mechanism that continuously injects an additive that changes friction performance into the lubricating oil in the circulation channel at a constant injection amount per unit time;
a stirring unit that stirs the lubricating oil after the additive has been injected by the injection mechanism in the circulation flow path;
an oil tank for storing lubricating oil circulating in the circulation flow path;
a measuring unit that continuously measures changes in the coefficient of friction over time from the start of injection of the additive by the injection mechanism using the lubricating oil stored in the oil tank;
Friction test equipment with 2. The friction according to claim 1, wherein the injection mechanism is a syringe pump that continuously injects the additive into the lubricating oil at a constant injection amount per unit time by pushing out the additive stored in the syringe with a plunger. test equipment. 3. The injection mechanism according to claim 2, wherein the injection mechanism is configured to be capable of injecting the additive every minute in a volume of 1/10000 or more and 1/100 or less of the total volume of the lubricating oil circulating in the circulation passage. Friction test equipment. 4. The measuring unit is a rotary friction coefficient measuring instrument which is installed in the oil tank and measures the friction coefficient by contacting a contactor to which a load is applied on a rotating disc-shaped sample. 1. The friction test device according to 1. 5. The friction test apparatus according to any one of claims 1 to 4, further comprising a filter for removing metal powder contained in lubricating oil flowing into said circulation passage from said oil tank.

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