Automatic measurement pendulum type oil friction tester and kit for modifying it

Abstract

Provided are: an automatic measurement pendulum-type oiliness friction tester that can automatically measure the angular velocity or oscillation angle of a damping vibration in a vertical plane of a pendulum without relying on a visual reading by a person in charge of testing, so as to accurately measure the coefficient of friction of a lubricating oil; and a kit for remodeling an existing pendulum-type oiliness friction tester to automatic measurement from visual measurement. One to three wireless or recording-type and battery-type gyroscopic sensors 20 are attached to approximately the same locations as attachment locations of a total of three weights, i.e., two weights attached to left and right horizontal parts 10L, 10R of an approximately T-shaped pendulum 10, and one weight attached to a vertical part 10U, and the weight of the weights is adjusted such that the total weight of the weights and the gyroscopic sensors at the attachment locations is a prescribed weight. The coefficient of friction of a lubricating oil is calculated from the angular velocity or oscillation angle of a support shaft connected to the pendulum 10 detected by the gyroscopic sensor 20.

Description

[Technical Field]

[0001] The present invention relates to an automatic pendulum-type oil-based friction tester that automatically measures the angular velocity or swing angle of the damped oscillation of a pendulum to calculate the friction coefficient of a lubricating oil using a formula when measuring the friction coefficient of the lubricating oil, and to a kit for modifying an existing pendulum-type oil-based friction tester from visual measurement to automatic measurement. [Background technology]

[0002] Among the lubricating properties of lubricating oils, the coefficient of friction (boundary friction coefficient) has long been measured as a quantitative indicator of the so-called oiliness. The magnitude of boundary friction varies not only depending on the type of lubricating oil, but also on the test method and measurement conditions. Therefore, the coefficient of friction is measured using specific equipment under specific conditions.

[0003] The pendulum type is the most typical method for measuring the coefficient of friction, and in Japan, the pendulum type oil friction tester invented by Professor Soda is widely used. There are two types of pendulum type oil friction testers, Type I and Type II, which differ in the shape of the friction surface, but this specification will mainly focus on the widely used Type II.

[0004] The pendulum-type oil friction test is characterized by its ability to determine the coefficient of kinetic friction under very low-speed sliding conditions, and its principle is to use the fulcrum of the pendulum as the friction surface. Since the damping of the pendulum oscillation is due to the friction moment of the friction surface, the friction surface is immersed in the lubricating oil to be tested, and the degree of damping is measured to calculate the coefficient of friction of the lubricating oil.

[0005] The structure of the pendulum-type oil-based friction tester 1 is as shown in Figure 1. The pendulum 10 is roughly T-shaped, with weights 11L and 11R attached to both ends of left and right horizontal sections 10L and 10R, and weight 11U attached to vertical section 10U, and the lower end of the vertical section forms pendulum pointer 12. The decrease in the swing angle of the pendulum 10 is measured visually from a scale plate 13 using this pendulum pointer 12.

[0006] The fulcrum of the pendulum and the friction surface are as shown in Figures 2(a) and (b). The fulcrum of the pendulum 10 is a support shaft (steel roller pin) 14, and the left, right, front, rear, and lower sides are supported by a total of four steel balls (bearing steel balls) 15. Therefore, the friction surface is made up of a total of four point contacts between the support shaft 14 and the steel balls 15. The configuration of these friction surfaces is contained within an oil tank 16.

[0007] A total of four steel balls 15, two at the front and two at the back, are placed in an oil tank 16 and lubricating oil is poured in. A roller pin 14 is set at the fulcrum in the center of the pendulum 10 and placed on the steel balls 15. Measurement begins by allowing the pendulum 10 to swing naturally from a certain angle (initial swing angle) to the left, and the maximum swing angle of the pendulum that has swung to the left is visually read from the pendulum pointer 12 and scale plate 13. The coefficient of friction is calculated from this swing angle of the pendulum and the number of swings until damping occurs.

[0008] Currently, major lubricant manufacturers that own pendulum-type oil friction testers measure the pendulum swing angle as described above by visually reading the position of the scale plate where the pendulum pointer points. Because the movement of the pendulum pointer, which swings back and forth, must be read visually in an instant, reading errors are likely to occur and there is also a tendency for individual differences to occur depending on the tester. This also places a heavy burden on the tester, requiring time and effort. Therefore, automating the reading of the pendulum swing angle is important from the perspective of improving measurement accuracy and saving labor.

[0009] Therefore, devices and methods for automating the reading of the swing angle of a pendulum have been proposed. For example, Patent Document 1 discloses an automatic measuring device for a pendulum-type oiliness tester in which a reflective scale (1 division = 0.01 radians) 3 is attached to the back surface of the central ring-shaped frame 2 of the pendulum 1, and a photoelectric light-emitting / receiving device 4 is disposed opposite this reflective scale 3 and fixed to the main body 5 of the tester.

[0010] This automatic measuring device is capable of automatically reading the swing angle of the pendulum with high precision (approximately 0.005 radians), doubling the measurement accuracy compared to previous models, eliminating individual differences in measurement results, and is said to streamline the traditional desk-based calculation of friction coefficients. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Publication No. 57-170050 Summary of the Invention [Problem to be solved by the invention]

[0012] In principle, the pendulum-type oil friction tester is designed to operate on the assumption that pendulum motion occurs only in the vertical plane. In other words, in Figure 1, the pendulum 10 oscillates only in the XY plane and swings only around the Z axis. However, the pendulum's support shaft is mounted on a bearing, allowing the pendulum to be attached and detached upward, and the pendulum's fulcrum is not fixedly connected. For this reason, in actual measurements, the pendulum 10 also swings around the X and Y axes in Figure 1, demonstrating through experiments conducted by the inventors that swings occur in the plane of motion of the pendulum 10. While subtle swings in the plane of motion of the pendulum have traditionally been confirmed visually, there have been no means or methods for accurately detecting this swing. The only available solution is to use a spirit level to ensure that the test specimen or oil tank is installed as horizontally as possible. This has prevented precise measurement and analysis of the swing in the plane of motion of the pendulum, nor has it been possible to attempt effective solutions.

[0013] The automatic measuring device for the pendulum-type oiliness tester described in Patent Document 1 has been put into practical use and is manufactured and sold. It can automatically read the swing angle of the pendulum with high accuracy, and measurement data can be saved on an SD card or other device and processed on a general-purpose PC. However, because a reflective scale 3 is attached to the central ring-shaped frame 2 of the pendulum 1 and a photoelectric light-emitter / receiver 4 is disposed on a support 16 facing the reflective scale 3, if the pendulum 1 swings around the X-axis or Y-axis, causing fluctuations in the plane of motion, the distance between the swinging reflective scale 3 and the fixed photoelectric light-emitter / receiver 4 fluctuates, affecting the measurement of the swing angle and resulting in errors. This is thought to be a major cause of measurement errors observed in friction coefficient measurements using this automatic measuring device.

[0014] Furthermore, the structure is complex and dense, with a precision reflective scale 3 attached to the central ring-shaped frame 2 of the pendulum 1 into which the oil tank 15 is inserted, and a highly sensitive photoelectric light-emitter / receiver 4 attached to a support 16 close to the oil tank 15. As a result, the reflective scale 3 and photoelectric light-emitter / receiver 4 may become soiled, damaged, deformed or fall off due to adhesion of lubricating oil or contact when attaching or detaching the pendulum, and regular maintenance and inspection are required to maintain performance.

[0015] In addition, the price of the pendulum-type oil friction tester (Type II) itself is approximately 1.5 million yen, and the automation equipment alone, such as the sequence controller, costs more than 1.5 million yen, making it a major obstacle to widespread use.

[0016] Another method for automating readings is to use a color laser coaxial displacement sensor to measure the swing angle. In this method, a rectangular reflector plate (5 mm x 200 mm) is attached to the middle of the pendulum pointer, perpendicular to the plane of the pendulum's oscillation, and a coaxial displacement laser beam is irradiated from the side onto the center of this reflector to measure the swing angle of the pendulum motion.

[0017] However, with this measurement method using a color laser coaxial displacement sensor, if a reflector perpendicular to the plane of the pendulum's oscillation is attached, it may create resistance to the pendulum motion and affect the oscillation angle and frequency. Also, the automation equipment, including the sensor and controller, alone costs over 1 million yen, making it expensive.

[0018] Another method is to attach an inclination angle sensor (potentiometer type sensor) to the pendulum pointer to measure the swing angle of the pendulum motion with high precision.

[0019] However, this potentiometer-based measurement method requires a power supply to the sensor, and currently there are no sensors that can transmit tilt angle data wirelessly. Therefore, attaching a wired sensor to the pendulum pointer would have a significant effect on the pendulum motion. While there are potentiometers that can be attached to the pendulum's central support shaft (roller pin), as shown in Figures 2(a) and (b), the pendulum's central support shaft is a cylindrical shaft made of bearing steel immersed in lubricating oil. Attaching a potentiometer to this support shaft would prevent the device from functioning as a test device to measure the friction coefficient.

[0020] If costs are disregarded, conventional technology is thought to be able to cope to some extent with this problem, but as mentioned above, conventional technology currently has several technical issues in terms of accurate automatic measurement of pendulum motion, device structure, manufacturing costs, etc.

[0021] The present invention has been made in consideration of the above-mentioned background art and its problems, and aims to provide an automatic measurement pendulum-type oil-based friction tester that has a simple structure and low manufacturing costs, yet is capable of automatically reading the pendulum swing angle with high accuracy, eliminating individual differences in measurement results, and enabling efficient calculation of friction coefficients. Another aim is to provide a kit or the like that can modify an existing pendulum-type oil-based friction tester from visual measurement to automatic measurement at low cost. [Means for solving the problem]

[0022] As a result of extensive research into solving the above-mentioned problems, the inventors discovered that by attaching a wireless or recording and battery-powered gyro sensor and weights for adjusting the weight to approximately the same locations as the weights attached to the left and right horizontal and vertical sections of a T-shaped pendulum, it is possible to simplify the structure and significantly reduce manufacturing costs, while also making it possible to accurately and automatically measure the swing angle of a pendulum without affecting its motion. As a result of further research, they have completed the present invention.

[0023] That is, the present invention provides a pendulum-type oil friction tester that is approximately T-shaped and has left and right horizontal portions and vertical portions, a total of three weights attached to the left and right horizontal portions and vertical portions, a cylindrical support shaft connected to a fulcrum at the center in the left and right direction, a support section that supports the pendulum so that it can swing, which has bearings consisting of a total of four steel balls that abut against the support shaft and support it from the left, right, front, back, and bottom, a base that supports the entire structure, a support column that extends vertically from the base, and an oil tank that contains the support section and is installed on top of the support column, wherein the support shaft and the bearings consisting of a total of four steel balls come into contact with a lubricating oil to be tested that has been poured into the oil tank, and the pendulum is swung in a vertical plane and the swing angle of the damped oscillation is measured, thereby measuring the friction coefficient of the lubricating oil. and a wireless, battery-powered gyro sensor having a wireless transmitting unit and capable of wirelessly transmitting data, one to three of the gyro sensors being attached at approximately the same locations as the attachment locations of a total of three weights attached to the left and right horizontal and vertical sections of the pendulum, the weights of the weights being adjusted so that the total weight of the weights at the attachment locations and the gyro sensor is a predetermined weight, and a receiving and recording device having a receiving unit that receives data wirelessly transmitted from the gyro sensor and a recording unit that records the received data, and the friction coefficient of the lubricating oil is measured from data on the angular velocity or swing angle of the support shaft connected to the pendulum measured by the gyro sensor.

[0024] The present invention also provides a pendulum having a substantially T-shape with left and right horizontal portions and vertical portions, with a total of three weights attached to the left and right horizontal portions and vertical portions, and a cylindrical support shaft connected to a fulcrum at the center in the left and right direction, a support section having bearings made of a total of four steel balls that abut against the support shaft and support it from the left, right, front, rear, and lower sides, and supporting the pendulum so that it can swing, a base that supports the entire pendulum, a support column extending vertically from the base, and an oil tank that contains the support section and is installed on top of the support column, and the support shaft and the bearings made of a total of four steel balls come into contact with the lubricating oil to be tested that has been poured into the oil tank, and the pendulum is swung in a vertical plane and the swing angle of the damped oscillation is measured, thereby measuring the above-mentioned This automatic pendulum-type oil-based friction tester is for measuring the coefficient of friction of a lubricating oil, and is equipped with a recording, battery-powered gyro sensor that has an internal recording unit and is capable of internally recording data. One to three of the gyro sensors are attached to locations approximately identical to the attachment locations of a total of three weights attached to the left and right horizontal and vertical sections of the pendulum, and the weights of the weights are adjusted so that the total weight of the weights at those attachment locations and the gyro sensor is a predetermined weight. The friction coefficient of the lubricating oil is measured from data on the angular velocity or swing angle of the support shaft connected to the pendulum, measured by the gyro sensor.

[0025] Furthermore, one embodiment of the present invention is the automatic measuring pendulum oil-based friction tester, wherein the gyro sensor is attached to approximately the same location as the attachment location of a weight attached to the vertical portion of the pendulum, and the weight of the weight is adjusted so that the total weight of the weight at the attachment location and the gyro sensor is a predetermined weight.

[0026] Another embodiment of the present invention is a method for measuring the friction coefficient of a lubricating oil, characterized in that the automatic measurement pendulum-type oil-based friction tester is used to automatically measure the angular velocity or the swing angle of the support shaft connected to the pendulum, thereby measuring the friction coefficient of the lubricating oil.

[0027] The automatic measuring pendulum oil friction tester and the measurement method using the same of the present invention can automatically read the angular velocity or swing angle of the damped oscillation of the pendulum with high accuracy, can eliminate individual differences in measurement results, greatly improve measurement accuracy, and can also efficiently calculate the friction coefficient.In addition, the automatic measurement mechanism is simple and robust, can significantly reduce manufacturing costs, and can omit maintenance and inspection, etc.

[0028] Furthermore, by using a gyro sensor, it is possible to measure the swing of the damped oscillation of the pendulum around the X and Y axes, which was not possible with conventional pendulum-type oil friction testers. By precisely measuring and analyzing the swing of the pendulum in its motion plane, it is possible to determine whether the calculated friction coefficient is appropriate and ensure the reliability of the measurement data.

[0029] Furthermore, one embodiment of the present invention is a kit for converting an existing pendulum-type oil-type friction tester into the automatic measurement pendulum-type oil-type friction tester, characterized by including one to three wireless or recording and battery-powered gyro sensors and at least one to three adjustment weights that are attached to substantially the same locations as the gyro sensors and that adjust the total weight of the gyro sensors to a predetermined weight.

[0030] Moreover, one embodiment of the present invention is a method for converting an existing pendulum type oil-type friction tester into the automatic measurement pendulum type oil-type friction tester, comprising the steps of: removing one to three weights from the conventional pendulum type oil-type friction tester; attaching one to three wireless or recording and battery-powered gyro sensors to approximately the same locations as the removal positions; and attaching at least one to three adjustment weights to approximately the same locations as the attachment positions so that the total weight of the gyro sensors and the wireless or recording and battery-powered gyro sensors becomes a predetermined weight.

[0031] With the conversion kit and conversion method using the same of the present invention, an existing pendulum-type oil-based friction tester can be converted, at a much lower cost than conventional ones, into the automatic measurement pendulum-type oil-based friction tester of the present invention, which can automatically and accurately measure the angular velocity or swing angle of the damped oscillation of the pendulum and further precisely measure and analyze the swing in the plane of motion of the pendulum. [Effects of the Invention]

[0032] According to the present invention, the angular velocity or swing angle of the damped oscillation of a pendulum can be automatically and accurately measured without affecting the oscillatory motion of the pendulum, despite its simple structure and low cost. This eliminates measurement errors without relying on visual reading, significantly improving the measurement accuracy of the friction coefficient. Furthermore, the oscillation of the pendulum's motion plane can be measured and analyzed, improving the reliability of the measured friction coefficient. Furthermore, the friction coefficient can be efficiently calculated using recorded data. Furthermore, because a testing machine with these excellent capabilities can be realized at low cost, it is expected to become widely used. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a front view showing a conventional pendulum-type oil friction tester (II type). [Figure 2] This is a schematic diagram showing the fulcrum and friction surface of a pendulum, where (a) is a front view from the front, and (b) is a plan view from above. [Figure 3] 1 is a front view showing an automatic measurement pendulum type oily friction tester according to a first embodiment of the present invention. [Figure 4] 4 is a partial enlarged view of part A in FIG. 3, where (a) is a front view, (b) is a right side view, and (c) is a perspective view of the gyro sensor mounting location. [Figure 5] FIG. 1 is an explanatory diagram showing an outline of the system of an automatic measurement pendulum type oily friction tester according to a first embodiment of the present invention. [Figure 6]1A and 1B are diagrams showing embodiments 2 and 3 of the present invention, in which (a) is a front view showing a pendulum equipped with three wireless gyro sensors, (b) is a partially enlarged bottom view and perspective view of part B thereof, and (c) is a front view showing a pendulum equipped with two recording gyro sensors. [Figure 7] 1 is a graph showing the measurement results of the swing angle around the Z axis of pendulum oscillation using the automatic measurement pendulum type oil friction tester of the first embodiment (dry friction, test ball SUJ2). [Figure 8] 1 is a graph showing the measurement results of the swing angle around the X axis and the Y axis of pendulum oscillation using the automatic measurement pendulum type oil friction tester of the first embodiment (dry friction, test ball SUJ2). [Figure 9] 1 is a graph showing the measurement results of the swing angle around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of the first embodiment (test oil L-Vis1, test ball SUJ2). [Figure 10] 1 is a graph showing the measurement results of the swing angle around the X axis and the Y axis of pendulum oscillation using the automatic measurement pendulum type oil friction tester of the first embodiment (test oil L-Vis1, test ball SUJ2). [Figure 11] 1 is a graph showing the measurement results of the swing angle around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of the first embodiment (dry friction, test ball A1050). [Figure 12] 1 is a graph showing the measurement results of the swing angle around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of embodiment 1 (test oil RF-520, test ball A1050). [Figure 13] 1 is a graph showing the measurement results of angular velocity around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of the first embodiment (dry friction, test ball SUJ2). [Figure 14] 1 is a graph showing the measurement results of angular velocity around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of embodiment 1 (test oil L-Vis1, test ball SUJ2). [Figure 15] 1 is a graph showing the measurement results of angular velocity around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of the first embodiment (dry friction, test ball A1050). [Figure 16]1 is a graph showing the measurement results of angular velocity around the Z axis of pendulum oscillation using the automatic measurement pendulum-type oil friction tester of embodiment 1 (test oil RF-520, test ball A1050). [Figure 17] 1 is a graph showing the decay tendency of angular velocity around the Z axis obtained by regression analysis of the relationship between test time and angular velocity around the Z axis (test oil L-Vis1, test ball SUJ2). [Figure 18] 1 is a graph showing the decay tendency of angular velocity around the Z axis, obtained by regression analysis of the relationship between test time and angular velocity around the Z axis (test oil P-123, test ball SUJ2). [Figure 19] 1 is a graph showing the decay tendency of angular velocity around the Z axis, obtained by regression analysis of the relationship between test time and angular velocity around the Z axis (test oil L-Vis1, test ball A1050). [Figure 20] 1 is a graph showing the decay tendency of angular velocity around the Z axis, obtained by regression analysis of the relationship between test time and angular velocity around the Z axis (test oil RF-520, test ball A1050). DETAILED DESCRIPTION OF THE INVENTION

[0034] Embodiments of the automatic measurement pendulum type oily friction tester of the present invention will be described in detail below with reference to the drawings, etc. Note that the present invention is not limited to these embodiments, and various modifications are possible within the scope of the technical concept of the present invention.

[0035] Furthermore, materials, structures, control methods, measurement methods, etc. for which description is omitted may be the same or substantially the same as those known to those skilled in the art. Furthermore, the same reference numerals in each drawing represent the same or equivalent components, and redundant description will be omitted. Note that in order to make the drawings easier to understand, some structures are omitted in the drawings.

[0036] In this specification, the testing machine is installed on a horizontal surface, and the front-to-back, left-to-right, and up-to-down directions are defined as directions along the Z, Y, and X axes shown in each drawing. More specifically, +Z defines the forward direction from the side from which the pendulum of the testing machine hangs, and -Z defines the backward direction. Furthermore, +Y defines the right direction when the front side of the testing machine is facing forward, and -Y defines the left direction. Furthermore, +X defines the downward direction from the installation surface side where the pedestal is in contact, and -X defines the upward direction. These directions are the same as the three axial directions of the Z, Y, and X axes detected by the gyro sensor provided in embodiment 1 of the present invention.

[0037] [Pendulum-type oil friction tester] The present invention has a basic structure based on the conventional pendulum-type oil friction tester 1. The basic structure may be created by fabricating an identical or equivalent tester, or a commercially available tester may be purchased and the pendulum portion modified. This specification focuses on the widely used Type II.

[0038] The structure of the pendulum-type oil-based friction tester 1 is as shown in Figure 1. The pendulum 10 is roughly T-shaped, with cylindrical weights 11L and 11R attached to the left and right ends of the horizontal sections 10L and 10R, 34 cm from the fulcrums. In addition, a cylindrical weight 11U is attached to the vertical section 10U at a position 10 cm below the fulcrum, and the lower end of the vertical section 10U forms a pendulum pointer 12. The decrease in the swing angle of the pendulum 10 is visually read from a scale plate 13 using this pendulum pointer 12.

[0039] The fulcrum and friction surface of the pendulum are outlined in Figures 2(a) and (b). In Type II, the fulcrum of the pendulum 10 is a support shaft (φ2 x 30 mm roller pin, hardened carbon steel with lapped finish) 14, which is supported by a total of four steel balls (3 / 16" bearing steel balls) 15 on the left, right, front, rear, and lower sides. The friction surface is made up of four point contacts between the support shaft 14 and the steel balls 15 on the left, right, front, rear, and lower sides.

[0040] The standard test conditions for the pendulum-type oil-based friction tester use the above-mentioned steel roller pin and bearing steel ball as the standard test specimen. In recent years, with the significant increase in cutting, grinding, and other processing of non-ferrous metals and non-metallic materials other than steel, non-metallic balls, such as plastic balls, ceramic balls, and carbon fiber reinforced plastic (CFRP) balls, are now being used in addition to steel balls. Using these various types of test specimens makes it possible to measure friction coefficients that more accurately reflect the operating conditions of the lubricating oil.

[0041] The entire structure forming these friction surfaces is housed in a cylindrical oil tank 16 equipped with a heater at the bottom. A predetermined amount of the lubricating oil to be tested is poured into the oil tank 16 and maintained at a predetermined temperature. In other words, the friction surfaces are in contact with the lubricating oil within the oil tank 16. A support column 18 extends vertically upward from the center of a roughly rectangular base 17 that supports the entire testing machine in a plan view, and the oil tank 16 is installed horizontally at the front of the upper part of the support column 18. The pendulum 10 is placed on a bearing consisting of a total of four steel balls 15 within the oil tank 16 so that the entire oil tank 16 is inserted into the central annular portion 10C of the pendulum 10. The pendulum 10 is supported so that it can swing around a support shaft 14 inserted into the oil tank 16 as a fulcrum, and hangs down vertically from the front side of the support column 18.

[0042] The measurement method is to operate the swing bar 19 to start the pendulum oscillation of the pendulum pointer 12 from an initial oscillation angle of 0.5 radians, visually read and record the damped oscillation angle after each oscillation, and calculate the friction coefficient of the lubricant using a specified formula. In other words, this utilizes the fact that the degree of damping of the oscillation angle due to frictional force at the fulcrum depends on the oiliness of the lubricant. The friction coefficient μ is given by the following formula.

[0043]

number

[0044] The standard test conditions are as follows: C=3.2. Horizontal load: 80g x 2 (34cm from the fulcrum) Vertical axis load: 40g (10cm from the fulcrum) Average contact pressure: 74 kg / mm 2 Maximum sliding speed: 1.0 mm / sec

[0045] As described above, with conventional testing machines and their measurement methods, the pendulum swing angle is read visually by the tester, resulting in low measurement accuracy and large individual differences, and the coefficient of friction is calculated manually, making it inefficient.The testing machine and its measurement method of the present invention can automatically and accurately measure the pendulum swing angle, thereby significantly improving measurement accuracy, eliminating individual differences, and further increasing efficiency by automatically calculating the coefficient of friction.

[0046] [Embodiment 1] As described above, the present invention has a basic structure based on the conventional pendulum-type oil-based friction tester 1. The structure of the automatic measurement pendulum-type oil-based friction tester 2 of the present invention is as shown in FIG. 3. In this embodiment, one wireless gyro sensor 20 is attached to the vertical section 10U of the pendulum 10 to measure the swing angle of the pendulum's damped oscillation. Generally, a gyro sensor can measure angular acceleration around three axes (X, Y, and Z) and calculate and output angular velocity and angle based on this data and the measurement time. In this embodiment, the measured change in angle around the Z axis is used as the swing angle in the motion plane (XY plane) of the pendulum's damped oscillation to calculate the friction coefficient.

[0047] Additionally, using a gyro sensor makes it possible to measure angular changes around the X-axis and Y-axis during the damped oscillation of the pendulum. These angular changes represent the swing of the pendulum's plane of motion, and swings in this plane of motion affect the measurement of angular changes around the Z-axis, causing errors. Therefore, by measuring the angular changes around the X-axis and Y-axis and observing and analyzing the swing of the pendulum's plane of motion, it is possible to determine the appropriateness of the measurement data and ensure its reliability.

[0048] Gyro sensors come in various types, such as mechanical, optical, and fluid, depending on their structure. However, since the present invention requires a small and lightweight design, a mechanical vibration-type gyro sensor is desirable. Furthermore, a wireless gyro sensor with a built-in wireless transmitter capable of wirelessly transmitting detected data, or a recording gyro sensor with a built-in recording unit such as a semiconductor memory capable of internally recording detected data, is desirable so as not to affect the damping oscillation of the pendulum. A battery-powered power source is desirable. In this embodiment, a rechargeable battery-powered gyro sensor capable of wirelessly transmitting data via Bluetooth communication is used (WitMotion, BWT61CL, dimensions: L 51 mm × W 35 mm × T 16 mm, weight: 20 g).

[0049] Based on standard test conditions, it is preferable to attach the gyro sensor 20 at approximately the same location as the attachment points of the weights 11L and 11R attached to both the left and right ends of the horizontal sections 10L and 10R extending left and right of the approximately T-shaped pendulum 10, 34 cm from the fulcrum, and the attachment point of the weight 11U attached at a position 10 cm below the fulcrum of the vertical section 10U extending downward.

[0050] One to three gyro sensors 20 can be attached to the pendulum 10, but even one is sufficient to measure the swing angle of the pendulum's damped oscillation with sufficient accuracy. One gyro sensor is preferable from the perspective of equipment settings for wireless transmission such as Bluetooth and manufacturing costs. Two to three gyro sensors are preferable from the perspective of more precise analysis of the pendulum's motion plane and system redundancy. When attaching one gyro sensor, it is preferable to attach it in approximately the same location as the attachment location of weight 11U attached to vertical section 10U, taking into consideration the balance of the weight and shape on the left and right sides of pendulum 10. When attaching two gyro sensors, it is preferable to attach them in approximately the same locations as the attachment locations of weights 11L and 11R attached to both the left and right ends of horizontal sections 10L and 10R, from the same perspective.

[0051] Since the horizontal axis load is 80 g × 2 under standard test conditions, when a gyro sensor is attached to the attachment location of weights 11L and 11R, the weight of the gyro sensor is preferably 80 g or less, and considering the front-to-back balance with the adjustment weight attached to the rear, a weight of 40 g or less is more preferable, and a weight of around 40 g is most preferable. Also, since the vertical axis load is 40 g, when a gyro sensor is attached to the attachment location of weight 11U, the weight of the gyro sensor is preferably 40 g or less, and considering the front-to-back balance with the adjustment weight attached to the rear, a weight of 20 g or less is more preferable, and a weight of around 20 g is most preferable. Note that if the weight of the gyro sensor exceeds the specified weight based on the specified test conditions, it can be adjusted by shortening the attachment distance from the fulcrum.

[0052] If the weight of the gyro sensor is less than the weight of the test condition weight, it is necessary to attach an adjustment weight at approximately the same location as the installation location of the test condition weight (the installation location of the gyro sensor) so that the total weight with the gyro sensor meets the test condition. In this case, it is preferable to process and attach the adjustment weight so that the load and shape in the front, back, left, and right directions are as uniform as possible so as not to affect the vibration motion of the pendulum 10. The material of the adjustment weight is not limited as long as it can perform the desired function. From the viewpoint of specific gravity and processability, metal materials are preferred, such as brass, stainless steel, steel, and aluminum. The material of the adjustment weights attached to both ends of the left and right horizontal sections, which are heavier, is preferably brass, stainless steel, steel, etc., which have a high specific gravity.

[0053] The gyro sensor and adjustment weight are attached to approximately the same location as the standard cylindrical weight attached to the pendulum of the pendulum-type oil-based friction tester. Here, "approximately the same location" means that the centers of gravity of the standard cylindrical weight and the gyro sensor and adjustment weight are close enough to each other so as not to substantially affect the damping vibration of the pendulum and not to cause significant errors in the friction coefficient measurement results. Specifically, in a front view in the front-to-back direction (XY plane view), the centers of gravity of the standard cylindrical weight and the gyro sensor and adjustment weight are preferably as close as possible. Furthermore, in a side view in the left-to-right direction (ZX plane view), the centers of gravity of the standard cylindrical weight and the gyro sensor and adjustment weight located at the front and rear of the flat pendulum are preferably as close as possible. The center of gravity of the gyro sensor may be determined by approximating it to a solid, such as a homogeneous rectangular parallelepiped, that most closely resembles its shape.

[0054] In this embodiment, as shown in FIGS. 4(a) to 4(c), the weight 11U (40g) attached 10 cm below the support shaft 14 of the vertical portion 10U extending vertically of the pendulum 10 is removed, and a gyro sensor 20 (BWT61CL, 20g) is attached to the front side of the vertical portion 10U at approximately the same location. A flat aluminum adjustment weight 21 weighing approximately 20g is attached to the rear side of the mounting surface of the gyro sensor 20 at approximately the same location, sandwiching the flat vertical portion 10U between them. Both components are attached using bolts and nuts, and the weight of the adjustment weight 21 includes the weight of fasteners such as bolts and nuts. A groove is carved into the mounting surface of the adjustment weight 21 so that the flat vertical portion 10U fits into it.

[0055] One or two gyro sensors may be attached to the mounting locations of weights 11L, 11R attached to horizontal sections 10L, 10R extending horizontally to the left and right of pendulum 10. In this case, similar to the above, to avoid affecting the damping vibration of pendulum 10, it is preferable to process and mount the weights and shapes of the mounting parts so that they are as uniform as possible on the front, back, left and right sides, and also to process and mount the weights and shapes of both ends of left and right horizontal sections 10L, R so that they are as uniform as possible.

[0056] In the present invention, the receiving / recording device 22, which includes a receiving unit that receives data wirelessly transmitted from the gyro sensor 20 and a recording unit that records the received data, is not limited as long as it has the predetermined functions and can achieve the effects of the present invention. The receiving / recording device 22 may also include a calculation unit that calculates predetermined items such as the friction coefficient from the received or recorded data, a display unit that displays the calculation results, and a control unit that controls movable parts such as a swing bar. Examples of the receiving / recording device and calculation / control unit that have the functions of each of these units include a programmable logic controller (PLC) for equipment control, a dedicated or general-purpose single board computer (SBC), and a general-purpose personal computer (PC). A general-purpose PC is preferable from the standpoints of operability, expandability, price, etc., but a smartphone or tablet computer may also be used.

[0057] In PLCs, SBCs, and general-purpose PCs, the receiving unit is a built-in or externally expanded wireless unit such as Bluetooth or Wi-Fi. The recording unit is internal memory such as RAM or ROM mounted on the circuit board of the PLC, SBC, or general-purpose PC, or external memory such as an SD card, USB memory, magnetic disk, or semiconductor disk that is connected externally. The calculation and control unit is the central processing unit (CPU) and its peripheral circuits mounted on the circuit board of the PLC, SBC, or general-purpose PC, and the software installed in the recording unit.

[0058] [Embodiment 2] 6(a) and 6(b) show the structure of the pendulum portion of the automatic pendulum-type oil-based friction tester 3 of the present invention, which is equipped with three wireless gyro sensors. In this embodiment, weight 11U (40 g) attached 10 cm below support shaft 14 of vertical section 10U extending vertically of pendulum 10, and weights 11L and 11R (80 g) attached to both ends of horizontal sections 10L and 10R extending horizontally 34 cm from the support shafts, are removed, and wireless gyro sensors 30U and 30L,R (WT901-IoT, 20 g, manufactured by WitMotion) are attached to approximately the same locations on the front of vertical section 10U and horizontal sections 10L and 10R, respectively, which can connect to a wireless LAN via Wi-Fi communication to wirelessly transmit data and enable multiple connections.

[0059] An adjustment weight 31U equivalent to 20 g is attached to the back side of the mounting surface of the gyro sensor 30U in approximately the same location as the flat vertical portion 10U, sandwiching it between them. Adjustment weights 31LB and RB equivalent to 40 g are attached to the back side of the mounting surface of the gyro sensors 31L and 31R in approximately the same location as the flat horizontal portions 10L and 10R, sandwiching them between them. Grooves are carved into the mounting surfaces of the adjustment weights 31U and 31LB and RB so that the flat vertical portion 10U and the horizontal portions 10L and 10R fit into them. Furthermore, adjustment weights 31LF and RF equivalent to 20 g are attached as spacers between the gyro sensors 30L and 31R and the flat horizontal portions 10L and 10R, sandwiching them in approximately the same location. The left and right gyro sensors 30L, 30R and adjustment weights 31LB, RB and 31LF, RF have the same shape and weight, and their mounting positions and mounting forms are symmetrical.

[0060] [Embodiment 3] The structure of the pendulum portion of the automatic measurement pendulum type oil-based friction tester 4 of the present invention, which is equipped with two recording gyro sensors, is shown in Figure 6(c). In this embodiment, the weights 11L, 11R (80g) attached to the horizontal sections 10L, 10R extending horizontally in the left and right directions of the pendulum 10 are removed, and recording gyro sensors 40L, R (manufactured by WitMotion, WT901SDCL Gen 2nd, 20g) with built-in SD card memory that can internally record data are attached to approximately the same positions on the front side of the horizontal sections 10L, 10R.

[0061] Adjustment weights 41LB, RB, each weighing 40 g, are attached to the backside of the mounting surfaces of the gyro sensors 40L, 40R in approximately the same locations as the flat horizontal portions 10L, 10R, sandwiching them. Adjustment weights 41LF, RF, each weighing 20 g, are attached to the backside of the mounting surfaces of the gyro sensors 40L, 40R, in approximately the same locations as the flat horizontal portions 10L, 10R, sandwiching them as spacers between the gyro sensors 40L, 40R and the flat horizontal portions 10L, 10R. The attachment method for these four adjustment weights is the same as in the second embodiment. In this embodiment, measurement data of the swing angle of the pendulum 10 is recorded in an SD card memory built into the gyro sensors 40L, 40R. After the measurement and recording, the SD card memory can be removed from the gyro sensors 40L, 40R, and the measurement data can be read and recorded using an SD card reader built into or connected to an external device such as a general-purpose PC. Predetermined parameters, such as the coefficient of friction, can then be calculated and displayed. Depending on the type of gyro sensor, the measurement data may be read and recorded by connecting the gyro sensors to an external device such as a general-purpose PC via a USB cable or the like.

[0062] By providing two or three gyro sensors as in the above embodiment, it is expected that more precise measurement and analysis of the damped oscillation and plane of motion of the pendulum, in which the complex motion in the three axial directions has become clear, can be achieved.

[0063] [Test Example 1] Using the test machine of embodiment 1 in which the standard weight 11U attached to the vertical part 10U of the pendulum 10 of the existing pendulum-type oil friction tester 1 was replaced with a gyro sensor 20 and an adjustment weight 21, the swing angle of the pendulum during damped oscillation was automatically measured.

[0064] Measurements were carried out for the lubrication configurations of steel / steel and steel / aluminum. The configurations of the pendulum fulcrum and friction surface are shown in Table 1 below. [Table 1]

[0065] Measurements were also conducted under dry conditions, with no lubricating oil poured into the oil tank, and wet conditions, with lubricating oil poured into the tank. Under wet conditions, measurements were conducted at room temperature (25-26°C) using several base oils with different viscosities used in industrial lubricants, as well as commercially available products. The test oils and their kinematic viscosities are shown in Table 2 below. [Table 2]

[0066] The pendulum began to oscillate from an initial oscillation angle of 0.5 radians, and the damped oscillation angle after each oscillation was measured with a gyro sensor. Data on the angular changes around the XYZ axes was received by a Bluetooth device attached to the gyro sensor installed on a general-purpose laptop and recorded using the included software. The data recording conditions were set to a baud rate of 9600 (20 Hz), static threshold of 1.098° / s, and bandwidth of 10 Hz. From the recorded data, a damping curve was graphed using general-purpose spreadsheet software, and the friction coefficient was calculated.

[0067] The measurement results of the angular change around the Z axis, i.e., the swing angle in the vertical plane (XY plane) of the damped oscillation of the pendulum 10, and the calculation results of the friction coefficient based on the above-mentioned Equation 1 are shown in Tables 3 and 4 below. Also, some of the graphs of the damping curves are shown in Figures 7 to 12.

[0068] [Table 3]

[0069] [Table 4]

[0070] The results in Tables 3 and 4 and Figures 7 to 12 show that the use of a gyro sensor allows for very stable, automatic measurement of the swing angle of the pendulum's damped oscillation. Furthermore, while the friction coefficient is somewhat high under dry conditions without the use of lubricant, it decreases when L-Vis1 is used, and the friction coefficient between steel and aluminum decreases significantly when RF-520, which is designed for aluminum lubrication, is used. However, the effect of reducing the friction coefficient was not as pronounced with other combinations.

[0071] The standard deviation of the friction coefficient in a total of five measurements under wet conditions was less than 10%. The inventor's experience shows that the measurement accuracy is significantly improved compared to conventional methods of measuring the friction coefficient by visually reading the swing angle of the pendulum using a pendulum-type oil-based friction tester, which often results in a variation of about 15%. Therefore, it can be seen that the use of the automatic measurement pendulum-type oil-based friction tester of the present invention minimizes the measurement error of the swing angle and enables accurate measurement of the friction coefficient of a lubricating oil.

[0072] 8 and 10 show the measurement results for the angle change around the X axis (swing angle in the YZ plane of the damped oscillation of the pendulum) and the angle change around the Y axis (swing angle in the ZX plane of the damped oscillation of the pendulum). These results show that in the damped oscillation of the pendulum of the pendulum-type oil friction tester, angle changes also occur around the X axis and the Y axis, and that the angle change around the X axis is particularly large. These angle changes indicate the oscillation of the plane of motion of the pendulum, and it is presumed that if this value is large, it will affect the measurement accuracy of the angle change around the Z axis.

[0073] Therefore, by measuring the angular changes around the X-axis and Y-axis and analyzing the swing of the pendulum's motion plane, it may be possible to determine whether the friction coefficient measurement is normal and improve its reliability. For example, if the angular changes around the X-axis or Y-axis exceed a predetermined value, it is possible to exclude the measurement data. In this test, the maximum angular change around the X-axis was 0.45 radians at the initial swing angle stage at the start of measurement. This is presumably due to factors such as the amount of force applied to the lever when manually operating the swing bar. However, this allows us to predict and confirm measurement accuracy at the start of measurement, allowing us to make an appropriate decision to stop the measurement. It is also possible to use the angular changes around the X-axis and Y-axis to correct the measurement data of the pendulum swing angle (angle change around the Z-axis) and the measurement data of the friction coefficient.

[0074] [Test Example 2] In the present invention, a gyro sensor is used, making it possible to measure angular velocity and sway angle based on data on angular acceleration and time. In the automatic measurement of the sway angle in Test Example 1 using the testing machine of Embodiment 1, the angular velocity ωz around the Z axis (roller pin serving as the support axis) was also automatically measured at the same time. Oscillation was started from an initial sway angle of 0.5 radians, and the measurement results of the angular velocity ωz around the Z axis at the lowest point of the pendulum motion (the angle of the Z axis is zero) are shown in Tables 5 and 6 below. Parts of the graphs of the decay curves are also shown in Figures 13 to 16. The values ​​of angular velocity ωz are shown multiplied by -10. The slope of the regression line, described below, was used as the decay rate of angular velocity ωz.

[0075] [Table 5]

[0076] [Table 6]

[0077] The results in Tables 5 and 6 and Figures 13 to 16 show that the gyro sensor can automatically and reliably measure the angular velocity ωz around the Z-axis (roller pin, the support axis). The friction coefficient calculation utilizes the fact that the degree of attenuation of the swing angle due to frictional force at the support point depends on the oiliness of the lubricant. At the same time, the degree of attenuation of the angular velocity at the lowest point for each swing depends on the oiliness (dynamic friction coefficient) of the lubricant. In other words, analyzing the temporal change in angular velocity around the Z-axis may enable the friction coefficient of the test lubricant to be determined. Calculating the friction coefficient using angular velocity, which directly indicates oiliness without the need for integration over time, may potentially improve the accuracy of friction coefficient measurement.

[0078] Figures 17 to 20 show some graphs obtained by regression analysis of the relationship between the test time and the angular velocity ωz around the Z axis (the roller pin serving as the fulcrum) in Tables 5 and 6. The values ​​of the angular velocity ωz on the vertical axis were multiplied by 10 to perform linear regression analysis. It can be seen that under each measurement condition, the coefficient of friction calculated based on the above-mentioned Equation 1 and the slope of the regression line show similar values. The correlation coefficient (R 2 ) were all above 0.999. [Explanation of symbols]

[0079] 1...pendulum type oil friction tester, 10...T-type pendulum, 10L...left horizontal section, 10R...right horizontal section, 10U...vertical section, 10C...central annular section, 11L, R...horizontal section weight, 11U...vertical section weight, 12...pendulum pointer, 13...scale plate, 14...support shaft (steel roller pin), 15...steel ball (bearing steel ball), 16...oil tank, 17...base, 18...support column, 19...swing bar. 2...Automatic measuring pendulum type oil friction tester, 20...Wireless gyro sensor, 21...Adjustment weight, 22...Receiving and recording device. 3...Automatic measurement pendulum type oil friction tester, 30L, R, U...Wireless gyro sensor (multi-connection), 31LB, RB...Adjustment weight, 31LF, RF...Adjustment weight (spacer). 4...Automatic measuring pendulum type oil friction tester, 40L,R...Recording gyro sensor, 41LB,RB...Adjustment weight, 41LF,RF...Adjustment weight (spacer).

Claims

1. a pendulum-type oil friction tester that is generally T-shaped and has left and right horizontal and vertical sections, with a total of three weights attached to the left and right horizontal and vertical sections, and a cylindrical support shaft connected to a fulcrum at the center in the left-right direction; a support section that pivotally supports the pendulum so that it can swing, the support section having bearings consisting of four steel balls that abut against the support shaft and support it from the left, right, front, back, and bottom, a base that supports the entire system, a support column that extends vertically from the base, and an oil tank that contains the support section and is installed on top of the support column, the support shaft and the bearings consisting of a total of four steel balls come into contact with a lubricating oil to be tested that has been poured into the oil tank, and the pendulum is swung in a vertical plane and the swing angle of the damped oscillation is measured, an automatic measurement pendulum oil-based friction tester comprising a wireless, battery-powered gyro sensor having a wireless transmitting unit and capable of wirelessly transmitting data, one to three gyro sensors attached at approximately the same locations as the attachment locations of a total of three weights attached to the left and right horizontal and vertical sections of the pendulum, the weights of the weights at the gyro sensor attachment locations being adjusted so that the total weight of the weights at the gyro sensor attachment locations and the gyro sensor is the weight of the weights that meet the test conditions selected for measuring the friction coefficient of the lubricating oil, and comprising a receiving and recording device having a receiving unit that receives data wirelessly transmitted from the gyro sensor and a recording unit that records the received data, and wherein the friction coefficient of the lubricating oil is measured from data on the angular velocity or oscillation angle of the support shaft connected to the pendulum measured by the gyro sensor.

2. a pendulum-type oil friction tester that is generally T-shaped and has left and right horizontal and vertical sections, with a total of three weights attached to the left and right horizontal and vertical sections, and a cylindrical support shaft connected to a fulcrum at the center in the left-right direction; a support section that pivotally supports the pendulum so that it can swing, the support section having bearings consisting of four steel balls that abut against the support shaft and support it from the left, right, front, back, and bottom, a base that supports the entire system, a support column that extends vertically from the base, and an oil tank that contains the support section and is installed on top of the support column, the support shaft and the bearings consisting of a total of four steel balls come into contact with a lubricating oil to be tested that has been poured into the oil tank, and the pendulum is swung in a vertical plane and the swing angle of the damped oscillation is measured, an automatic measuring pendulum oil-based friction tester comprising a recording and battery-powered gyro sensor having an internal recording unit capable of internally recording data, one to three gyro sensors attached to approximately the same locations as the attachment locations of a total of three weights attached to the left and right horizontal and vertical sections of the pendulum, the weights of the weights at the gyro sensor attachment locations being adjusted so that the total weight of the weights at the gyro sensor attachment locations and the gyro sensor is the weight of the weights that meet the test conditions selected for measuring the friction coefficient of the lubricating oil, and the friction coefficient of the lubricating oil is measured from data on the angular velocity or swing angle of the support shaft connected to the pendulum measured by the gyro sensor.

3. 3. The automatic measurement pendulum type oil-based friction tester according to claim 1 or 2, wherein one gyro sensor is attached to a location substantially identical to the location where the weight attached to the vertical portion of the pendulum is attached, and the weight of the weight at the gyro sensor attachment location is adjusted so that the total weight of the weight at the gyro sensor attachment location and the gyro sensor becomes the weight of the weight that meets the test conditions selected for measuring the friction coefficient of the lubricating oil.

4. 3. A method for measuring the friction coefficient of a lubricating oil, comprising: using the automatic measurement pendulum-type oil-based friction tester according to claim 1 or 2; automatically measuring the angular velocity or the swing angle of the support shaft connected to the pendulum; and measuring the friction coefficient of the lubricating oil.

5. 3. A kit for converting an existing pendulum-type oil-type friction tester into the automatic measurement pendulum-type oil-type friction tester according to claim 1 or 2, comprising one to three wireless or recording and battery-powered gyro sensors, and at least one to three adjustment weights that are attached to substantially the same locations as the gyro sensors and that are used to adjust the total weight of the gyro sensors to a weight that meets the test conditions selected for measuring the friction coefficient of the lubricating oil.

6. 3. A method for converting an existing pendulum type oil-type friction tester into the automatic measurement pendulum type oil-type friction tester according to claim 1 or 2, comprising the steps of: removing one to three weights from the existing pendulum type oil-type friction tester; attaching one to three wireless or recording and battery-powered gyro sensors to approximately the same locations as the removal positions; and attaching at least one to three adjustment weights to approximately the same locations as the attachment positions so that the total weight of the gyro sensors and the weights becomes the weight of the weight that meets the test conditions selected for measuring the friction coefficient of the lubricating oil.

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