Friction testing apparatus and method

Abstract

The present invention relates to a test apparatus (1) for measuring the frictional properties of a fluid or the properties of a sample immersed in a fluid, the test apparatus (1) having a first sample holder (10). The holder holds the first sample (13) in the fluid under test such that the first sample (13) is in contact with the surface of the second sample (14) in the second sample holder (15). Means are provided for applying a measurable load between the two samples. A vibration driving means vibrates the first sample holder along a first direction relative to the second sample holder, and a (rigidity) force measuring means (24) measures the frictional force between the two samples. Since the sample holders (10, 15) are located in a sealed pressure chamber (4), it is possible to perform tests under different pressures, and a push rod (9) is provided to vibrate the first sample holder (10) in the pressure chamber (4), so that the pressure can be maintained during testing. The pressure chamber is removable and can maintain pressure or vacuum even when it is removed from the rest of the test apparatus (1).

Description

Technical Field

[0001] The present invention relates to an apparatus and method for testing the lubricating properties of liquids, gases or other fluids and / or the friction and wear properties of materials. Such an apparatus simulates the operating conditions of mechanical devices such as movable parts and fluid lubricating oils, for example fuel pumps and gearboxes. In these devices, it is possible to measure the conditions of lubricants and other fluids during testing, and to measure the movable parts during testing and the forces acting on these movable parts. From these measured values, it is generally possible to test new materials, lubricants or other fluids before the sale of new products or before introducing new products as components.

Background Art

[0002] Reproducing reliable results for a wide range of test fluids in different environments is an important function and characteristic for such test devices. Under the conditions considered to be encountered when using test fluids, the characteristics of the test fluids need to accurately grasp the correlation, and the reliability of the wear of the test samples depends on these results.

[0003] British Patent No. 2,227,0387 discloses an apparatus for testing lubricity using a rigid push rod.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide an improved test apparatus for testing fluids and / or materials under conditions close to the actual conditions that the fluid or material will experience. [Means for solving the problem]

[0006] This invention provides a test apparatus and method as described in the claims. [Brief explanation of the drawing]

[0007] The present invention is illustrated in the attached drawings for illustrative purposes only. [Figure 1] Figure 1 is a perspective view showing a test apparatus according to a first embodiment of the present invention. [Figure 2] Figure 2 is a side view showing the front portion of the test apparatus shown in Figure 1, into which the test section engages. [Figure 3] Figure 3 is a front end view showing the test apparatus of Figure 1. [Figure 4] Figure 4 is an enlarged perspective view showing the front portion of the test apparatus shown in Figure 1. [Figure 5] Figure 5 is a schematic side cross-sectional view showing the front portion of the test apparatus in Figure 1. [Figure 6] Figure 6 is a perspective view showing the front portion of the test apparatus after it has been separated from the test apparatus. [Modes for carrying out the invention]

[0008] The attached drawings show one main embodiment of the test apparatus according to the present invention. This test apparatus has a front section 3 and a housing 2 to which an upper sample 13 and a lower sample 14 can be attached. The upper sample 13 is releasably held within the upper sample holder 10 by a grub screw 12. The upper sample 13 is made of a spherical test material. In other embodiments, the lower sample may be its test material and / or a fluid that comes into contact with the upper and lower samples 13 and 14. The upper sample holder 10 is attached to a push rod 9 by a support block 11, and this push rod is connected to an electromagnetic vibrator (not shown) and installed inside the housing 2. In this test, the upper sample 13, which is a test ball, is vibrated while a load is applied to the lower sample 14, which is in the shape of a test disc.

[0009] After each test, the width, length, and depth of the worn areas or wear marks on either the upper sample 13 or the lower sample 14, or both, are measured. This correlates with the wear resistance characteristics of either sample and / or the frictional characteristics of the fluid under test.

[0010] In this embodiment, a fully sealed pressure chamber 4 is provided around the contact area of ​​the upper and lower samples 13 and 14, allowing the test to be performed under high pressure or vacuum. The front part 3 of the apparatus is removable, and this pressure chamber 4 maintains pressure or vacuum even when it is removed and moved to another location from the test apparatus 1, and the test blend (combination test formulation) can be prepared at a location away from the rest of the test apparatus 1. Figure 6 shows the front part 3 separated for pressure application at a different location.

[0011] Since the tests can be conducted using the same pressure and temperature conditions that would be experienced during actual use, the fuel and lubricant, or the parts that come into contact with them, can be tested quickly, reliably, and at low cost.

[0012] The pressure chamber 4 is enclosed by three parts: a removable lid 5 with a glass window 6, an upper chamber section 7, and a lower chamber section 8.

[0013] The lower sample holder 14 has an upright wall 16 for containing the test fluid 17 as needed.

[0014] The upper sample holder 10 is located within the upper support block 11, to which two metal bellows 18a and 18b are attached. These bellows extend from each side of the support block 11 and are attached to the inner wall 19 of the upper chamber portion 7. The bellows 18a and 18b are flexible around the push rod 9 to allow lateral vibration of the ball-shaped upper sample 13 and apply a load to the disc-shaped lower sample 14 to maintain a sealed pressure chamber 4 to maintain pressurized gas or vacuum within the pressure chamber 4. Thus, the push rod 9 is coupled to an external vibrator (not shown) located within the housing 2 by a decoupling push rod coupling 9a, allowing the ball-shaped upper sample 13 to be driven in a reciprocating motion.

[0015] The push rod 9 is attached to load supports 25a and 25b which are diametrically opposed by a support ring 25, so that weights can be suspended from the load supports 25a and 25b according to the load that you want to maintain between the samples 13 and 14 during testing.

[0016] The lower sample holder 15 is attached to the lower support block 20, which forms part of the lower chamber 8. The two thin discs 21a and 21b are attached to the respective block ends 22a and 22b in the central region of the discs 21a and 21b, and the discs 21a and 21b are fixed to the inner surface of the lower chamber 8 in the circumferential region of the discs 21a and 21b. The discs 21a and 21b are flexible in the axial direction but rigid in the radial direction. Because these discs 21a and 21b act as flexible seals, they can maintain pressurized gas or vacuum inside the pressure chamber 4 inside the discs 21a and 21b, and can withstand the ambient pressure applied outside the pressure chamber 4 outside the discs 21a and 21b. The lower support block 20 is also attached to a high-stiffness force transducer 24 by a push rod 23. The relative stiffness of the force transducer 24 to the flexible discs 21a and 21b means that a high proportion of the frictional force is applied to the force transducer, and since the combination of discs 21a and 21b and the arrangement of the force transducer 24 are sufficiently or completely elastic, the signal from the force transducer 24 is directly proportional to the frictional force applied to the lower test specimen 14. As described above, the lower specimen holder 15 is supported at both ends by the two flexible discs 21a and 21b. Since there is no physical contact except between the two specimens 13 and 14, all the frictional force is transmitted to the two discs 21a and 21. The discs 21a and 21b have relatively low axial stiffness compared to the force transducer 24 that connects the lower specimen holder 15. The discs 21a and 21b act as means of sealing the pressure chamber 4, so that a pressure or vacuum of 10 bar or less can be maintained in this pressure chamber. When a vacuum is present in the pressure chamber 4 and no test fluid is present, heat can only be transferred to the lower sample holder 15 through the discs 21a, 21b and their separation pads 26a, 26b, which act as supports that need to be electrically insulated.For the disks 21a and 21b, it is preferable to form them with nickel-plated beryllium copper (BeCu). For the insulating pad supports 26a and 26b, it is preferable to form them with anodized aluminum. Both are very good heat conductors, and when aluminum is anodized, it becomes an electrical insulator.

[0017] Continuing the explanation with reference to FIGS. 5 to 8, the lower chamber portion 8 has a pressure bore hole 34, to which a pressure line 35 is attached, and a fluid under positive or negative pressure can be introduced into or drawn out from the pressure chamber 4. Three pressure lines 35a, 35b, and 35c are provided radially around the lower chamber portion 8. The pressure line 35a has not only a pressure gauge 36 but also a proportional safety valve 39. The pressure lines 35a and 35b have an operating valve 37 for controlling the introduction or withdrawal of the fluid, and also have a safety relief valve 38.

[0018] The disks 21a and 21b are electrically insulated from the inner wall by, for example, insulating pads 26a and 26b, and an electrical insulation coupling 27 is provided between the push rod 23 and the force transducer 24, so that the entire configuration of the transducer is electrically insulated. Thereby, a current passing through the contact between the samples can be applied, and its resistance can be measured, or the effects of different voltages or currents applied to the contact operation can be examined.

[0019] The lower sample holder support block 20 has a bore hole 28 that facilitates the insertion of the temperature measurement probe 29.

[0020] The lid 5 (pod lid 5), the upper chamber portion 7, and the lower chamber portion 8 form a sealed chamber 4 that is fixed in place by four long screws 30. The whole is attached to the heater block 31 by four short screws 32. This heater block 31 has a cartridge heater 33, heats the sealed chamber 4, and controls the temperature according to the input from the temperature measurement probe 29 input to the temperature controller 34.

[0021] By removing the four short screws 32 and removing the clamp from the force transducer coupling 27 and the push rod coupling 9a, the entire pressure chamber test apparatus 3 can be removed from the test apparatus 1 while maintaining the pressure in the sealed chamber (pressure chamber) 4. Thus, test blends can be made in the sealed chamber (pressure chamber) 4 separated from the remaining part of the test apparatus 1.

[0022] The heater cartridge 34 in the temperature adjustment block 31 can be equipped with an electric heater or a cooling element, which enables tests to be carried out at high or low temperatures by means of the temperature measurement probe 29 and the controller. The temperature adjustment block 16 is attached to the bending support. This support is designed to be rigid in all directions except the vibration direction of the upper sample 13 and can flex in the vibration direction.

[0023] The lower sample holder 15 is preferably configured as a stainless steel bath for containing the test lubricant. The lower sample holder 15 configured as a bath has a vertical wall 16 for clamping the lower sample. The lower sample holder 15 can hold a small amount of test fluid or test grease, or it can be a dry contact. The remaining volume part of the pressure chamber can be filled with test gas, compressed gas, or it can be under vacuum.

[0024] Alternatively, the lower sample holder can be configured as a flat plate for clamping the lower sample 14. In this case, the lower half of the pressure chamber 4 is filled with the test fluid, and the test sample is immersed and filled in contact with this test fluid. The upper half of the test fluid can be filled with compressed gas or be under vacuum with test gas. When clamping to the flat plate, this lower sample 14 can be coated with test grease or be a dry contact, and the remaining volume part of the pressure chamber filled with compressed gas can be filled with compressed test gas or be under vacuum.

[0025] The apparatus of the present invention makes it possible to measure the electrical resistance of the contact point between two samples. This resistance is determined by the degree of asperity to asperity contact between the samples and serves as a qualitative measure of the effectiveness of the lubricant during sample separation.

[0026] During these measurements, it is possible to change the load, sample temperature, and sample pressure parameters using the method described above. [Explanation of Symbols]

[0027] 1: Test equipment 2: Housing 3: Front, pressure chamber test apparatus 4: Pressure chamber, sealed chamber 5: Detachable lid 6: Glass window 7: Upper chamber part 8: Lower chamber part 9: Pushrod 9a: Pushrod coupling 10: Upper sample holder / First sample holder 11: Support Block 12: Grub screws, set screws 13: Upper sample / First sample 14: Lower sample / Second sample 15: Lower sample holder / Second sample holder 16: Upright wall 17: Test fluid 18a, 18b: Bellows 19:Inner wall 20: Lower support block 21a, 21b: Disk 22a, 22b: Block ends 23: Pushrod 24: (Rigid) Force transducer 25: Support ring 25a, 25b: Load bearing body 26a, 26b: Insulating pads 27: Insulating coupling 28: Borehole 29: Temperature measuring probe 30: Long screw 31: Heater Block 32: Short screws 33: Heater Cartridge 34: Pressure bore hole 35a, 35b, 35c: Pressure lines 36: Pressure gauge 37: Pressure-operated valve 38: Pressure safety valve 39: Proportional valve

Claims

1. A test apparatus 1 for measuring the frictional properties of a fluid and the frictional properties of a sample immersed in a fluid, comprising: a first sample holder 10 made to hold the first sample 13 in the fluid to be tested such that the first sample surface of the first sample 13 is in contact with the second sample surface of the second sample 14 located within the second sample holder 15; means for applying a measurable load between these two samples; and a vibration driving means for vibrating the first sample holder along a first direction relative to the second sample holder; and a means 24 for measuring the frictional force between these two samples. The test apparatus 1 has a sealed pressure chamber 4 in which the first and second sample holders 10 and 15 are arranged so that tests can be performed under different pressures, a push rod 9 is provided which connects the vibration driving means to the first sample holder 10, and sealing means 18a and 18b are used to maintain the pressure in the pressure chamber 4 during the test, the push rod 9 vibrates the first sample holder 10 in the pressure chamber 4.

2. The test apparatus 1 according to claim 1, wherein the front part 3 of the test apparatus, which includes the pressure chamber 4, can be detached while maintaining the pressure or vacuum when separated from the rest of the test apparatus 1 to another location.

3. The test apparatus 1 according to claim 1, wherein the pressure chamber 4 has a removable lid 5 equipped with a glass window 6.

4. The test apparatus 1 according to claim 1, wherein the pressure chamber 4 has an upper chamber portion 7 and a lower chamber portion 8.

5. The test apparatus 1 according to claim 1, wherein the second sample holder 14 has an upright wall 16 for containing the test fluid 17 as needed.

6. The test apparatus 1 according to claim 1, wherein the first sample holder 10 is located within the upper support block 11 and is attached to a sealing means in the form of two metal bellows 18a, 18b that extend from both sides of the upper support block 11 and are attached to the inner wall 19 of the upper chamber portion 7.

7. The test apparatus 1 according to claim 1, wherein the push rod 9 is connected to an external vibration device (not shown) provided in the housing 2 that enables the reciprocating motion of the first sample 13 by a push rod coupling 9a that can be detached.

8. The test apparatus 1 according to claim 1, wherein the lower sample holder 15 is attached to the lower support block 20 which constitutes a part of the lower chamber portion 8.

9. The test apparatus 1 according to claim 1, wherein the two thin discs 21a and 21b are attached to the respective block ends 22a and 22b in the central region of the discs 21a and 21b, and the discs 21a and 21b are fixed to the inner surface of the lower chamber portion 8 in the circumferential region of the discs 21a and 21b.

10. The test apparatus 1 according to claim 9, wherein the disks 21a and 21b are flexible in the axial direction and difficult to bend in the radial direction.

11. The test apparatus 1 according to claim 9, wherein the discs 21a and 21b act as flexible seals to maintain pressurized gas or a vacuum inside the pressure chamber 4 inside the discs 21a and 21b, and resist the ambient pressure outside the pressure chamber 4 outside the discs 21a and 21b.

12. The lower support block 20 is attached to the force transducer 24 by a push rod 23, the test apparatus 1 according to claim 8.

13. The test apparatus 1 according to claim 12, wherein the rigidity of the force transducer 24 is set to be relatively high compared to the rigidity of the flexible disks 21a and 21b so that most of the frictional force between the samples is applied to the force transducer, and the composite configuration of disks 21a and 21b and the force transducer 24 exhibits sufficient elasticity so that the signal from the force transducer 24 is directly proportional to the frictional force applied to the lower sample 14.

14. The test apparatus 1 according to claim 10, wherein the disks 21a and 21b are electrically insulated from the inner wall of the lower chamber portion 8.

15. The test apparatus 1 according to claim 1, wherein an electrically insulating coupling 27 is provided between the push rod 23 and the force transducer 24, electrically insulating the entire force transducer 24.

16. The test apparatus 1 according to claim 8, wherein the lower sample holding support block 20 has a bore hole 28 that facilitates the insertion of a temperature measuring probe 29.

17. The test apparatus 1 according to claim 16, further comprising a heater block 31 that incorporates a cartridge-type heater 33 that heats the pressure chamber 4 by controlling the temperature based on the input from the temperature measuring probe 29 to a temperature controller 34.

18. The test apparatus 1 according to claim 7 or 15, wherein, while maintaining pressure in the pressure chamber 4, the force transducer coupling 27, the push rod coupling 9a, and the entire pressure chamber test apparatus 3 can be removed from the test apparatus 1, and a test blend can be prepared in the pressurized pressure chamber 4 separated from the rest of the test apparatus 1.

19. The test apparatus 1 according to claim 4, wherein the lower pressure chamber portion 8 has at least one pressure bore hole 34 into which pressure lines 35a, 35b, and 35c are attached.

20. The test apparatus 1 according to claim 19, wherein an operating valve 37 is provided in the pressure lines 35a, 35b, and 35c.

21. The test apparatus 1 according to claim 19, wherein a pressure gauge 36 is provided in the pressure lines 35a, 35b, and 35c.

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