JPS6329732Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Technical field: This invention is designed to prevent automobile wheel bearings from being stopped.
This invention relates to an automobile wheel bearing that is filled with an appropriate lubricant to prevent fretting corrosion that occurs at the parts where rolling elements contact the raceway surfaces of inner and outer rings due to repeated vibrations from the outside. Conventional technology Conventionally, wheel bearings for automobiles usually use a pair of tapered roller bearings or double row ball bearings, and a thickener containing lithium soap inside them is used.
Grease with a base oil viscosity of 140-210 cst/40°C at 220-295/25°C is sealed as a lubricant and used with a light preload or a slight clearance in the axial direction. However, when using transportation methods such as long-distance freight car transportation, the vertical vibrations and lateral vibrations that occur continuously and repeatedly at each joint of the rail combine to have a complex effect on the bearings, and even through tires, the rolling elements As impactful and repeated loads are applied to the contacting raceway surfaces of the inner and outer rings, fretting and corrosion occur in those areas, resulting in wear marks. As a result, the vehicle generates abnormal noises and vibrations during actual driving, which not only makes the ride uncomfortable but also causes problems such as shortening the life of the bearings. Therefore, as measures to prevent fretting and corrosion, attempts have been made to increase the preload on the bearings or take measures to adjust the tire pressure.
However, each of these methods has its own problems. That is, regarding the preload of the bearing, the preload load is usually set at an upper limit of about 300 kg in the axial direction, but if this upper limit is exceeded, the life of the bearing will be rapidly reduced, so it is not preferable to increase the preload. on the other hand,
Adjusting the tire pressure is a hassle as you have to take it to a local repair shop and have it readjusted once you arrive at your destination. Purpose of the invention This invention was created by focusing on the above-mentioned problems. Even when transporting a vehicle with a lot of vibration by freight car, the inner and outer wheels that come into contact with the rolling elements of the automobile wheel bearing while the vehicle is stopped. Prevents frenching corrosion from occurring on the raceway surface of the vehicle, and when used in rotation, selects and seals in grease that has the desired consistency suitable for this purpose, thereby preventing abnormal noise or shortening the service life of the vehicle. The purpose of the present invention is to provide a wheel bearing for use in automobiles, and to solve these problems. Embodiment Hereinafter, an embodiment of this invention will be described based on drawings and graphs. First, I will explain the configuration. Fig. 1 is a longitudinal cross-sectional view showing the state of the part where this automobile wheel bearing is installed in a vehicle, where s is an axle, h is a hub spline-fitted to the axle s, and the outer periphery of the inner part hn. The inner end surface 1n of the rolling bearing 1 fitted into the wheel bearing 1 is crimped and fixed to the stepped portion sd of the axle s and the stepped portion nd of the nutcle n by tightening a fixing nut k screwed into the wheel bearing 1 from the tip of the axle s. The outer end surface 1g of is restrained by a retaining ring t. In addition, 2 is a rolling element, 3 is an outer ring, 3k is a raceway surface of the outer ring 3 that is in contact with the rolling element 2, 4 is an inner ring, 4
k is the raceway surface of the inner ring 4 that is in contact with the rolling elements 2, 5 is a seal for preventing grease leakage, 6 is sealed grease, and c is an outer seal. That is,
The weight of the vehicle is supported by the rolling elements 2 between the raceway surface 3k of the outer ring 3 and the raceway surface 4k of the inner ring 4 via an oil film of grease 6. Grease 6 uses a urea compound as a thickener and mineral oil as a base oil, and has a low mixing consistency.
300-340/25℃, base oil viscosity is 80-130cst/40℃. By the way, the technical idea of this invention is that during freight car transportation of a vehicle that is hardly running,
By maintaining the repairability of the lubricating oil film on the contact surface between the raceway surfaces 3k and 4k of the wheel bearing 1 and the rolling elements 2, lubrication can be kept in a suitable state and the occurrence of fretting corrosion can be prevented. Therefore, the mixing consistency should be set to 300~
340/25℃, and when it starts running on the market, it is difficult to leak due to the rotation of the bearing 1, and it has an appropriate consistency due to the heat generation and shearing of the grease due to the rotation of the bearing 1. The aim is to use a lubricant that has the same properties as grease that uses lithium soap as a thickener, which has a consistency that changes to 220-295/25°C and then becomes stable. The viscosity of the base oil used as vehicle grease is
It is preferable to select 80-130 cst/40°C. This is because, from the point of view of preventing the occurrence of fretting and corrosion, the base oil viscosity may be 30 to 130 cst/40°C because the wear depth is small as shown in Figure 4, but under heavy loads such as vehicles. For applications with a large 〓=1.2 is equivalent to
This is because it is 80cst/40℃, which must be the lower limit. In order to realize the above technical idea, Grease U, which uses a urea compound as a thickener and is disclosed in Japanese Patent Publication No. 39-3114, is suitable. By the way, this grease U is
From the experimental results shown in the graph of the figure, it has been found that this device meets the purpose of this invention. In other words, according to the experimental values obtained by determining the change in mixing consistency with temperature after the shell roll test shown in Figure 2, Grease L using lithium soap as a thickener changes from 280/25℃ as the temperature increases. It changes almost linearly until it reaches 338/130°C, softens, and leaks from the bearing, so it is difficult to meet the purpose of this invention. On the other hand, urea-based grease U
Cures linearly from 25℃ to 242/100℃,
This value is maintained even at 130℃. Also,
The change over time in the hardness of the grease during heating shown in Figure 3 varies depending on the heating temperature, but when comparing the case when heated to 100°C, it is found that lithium soap-based grease L maintains the initial value for immiscible consistency up to 50 hours.
In contrast, urea-based grease U maintains a softened state at an almost constant temperature of 311/25°C, which is close to 312/25°C, whereas urea-based grease U, which initially had a temperature of 311/25°C, reached a temperature of 258/25°C after 10 hours.
It is presumed that the temperature suddenly decreased to 25℃, and the rate of decrease gradually decreased until it reached 245/25℃ in 50 hours, and that the curing state continued after that, maintaining a constant value. Therefore, in order to limit the base oil viscosity and mixing consistency suitable for the purpose of this invention, urea-based grease U
Various test products were prepared as shown in Table 1 and the necessary experiments were conducted.

[Table] In the fretting wear test (consistency: 310 to 330, conditions: 1 million repetitions) to measure the influence of viscosity shown in the graph of Figure 4, test grease D (base oil viscosity 143cst/40℃) was The wear depth is about 2 compared to other test greases B and J (base oil viscosity: 130cst/40℃).
Since the value is twice as high as 1 μm and is not suitable, it is determined that the upper limit of the base oil viscosity is 130 cst/40°C. As mentioned above, sample Grease C has a wear depth of 0.4μm or less, so it can be applied to lightweight items such as motor rotors, but for vehicles, the lower limit of base oil viscosity is 80cst/40℃. It is excluded because it is Next, we conducted a fretting wear test (base oil viscosity: 122 cst/40
℃, conditions: 1 million repetitions), the wear depth of test grease E (mixing consistency: 285/25°C) is greater than that of other test greases with mixing consistency of 300/25°C.
1.35μm, which is nearly twice as high as that of 0.7μm or less.
From this, it can be seen that the lower limit of the consistency value is 300. Next, in the ASTM leakage test (104℃, 6hr) shown in the graph in Figure 6, we conducted a grease leakage test using bearings, and found that the higher the mixing consistency value, the more the leakage amount tends to be. but,
In particular, the test grease G (mixing consistency 340/25℃) was 2.25
Compared to g, test grease H (mixing consistency 345/25℃)
is 3.75g even though there is only a slight difference in mixing consistency of 5/25℃
Since it was found that the amount of leakage increased by about 1.66 times, it was decided to set the mixing consistency value at 340 as the upper limit. That is, based on the above three types of experimental data,
The technology of this invention is achieved by filling the rolling bearing 1 with a grease 6 that uses a urea compound such as polyurea or diurea as a thickener and has a base oil viscosity of 30 to 130 cst/40°C and a mixing consistency of 300 to 340/25°C. It becomes possible to realize ideas. Next, we will discuss the effect. Grease 6 sealed in this wheel bearing 1
When used in vehicle bearings, the base oil viscosity is 80
~130cst/40℃, the thickness of the oil film of the grease 6 interposed between the rolling elements 2 and the inner and outer rings 3, 4 is such that the oil film parameter 〓 is kept at 1.2 or more, and the mixing consistency is 300~340/ The selected temperature of 40℃ also alleviates the impact load associated with the complex vibrations experienced during long-term freight car transportation, reduces wear, and prevents fretting and corrosion from occurring on the raceway surfaces 3k and 4k. prevent. In addition, during actual running, the grease hardens due to the heat generated by rotation and the shearing of the grease, resulting in very minimal leakage and no wear marks, allowing smooth running without abnormal noises. Effects of the invention As explained above, this invention uses a urea compound as a thickener, and the base oil viscosity is 30 to 130cst/40cst.
In order to provide automotive wheel bearings filled with grease with temperature and mixing consistency of 300-340/25℃,
Fretting/fretting on the inner and outer raceway surfaces of the bearing.
It prevents corrosion and eliminates the need for maintenance before use, and also ensures smooth operation without causing unpleasant noise or vibration during actual rotational use, reducing maintenance man-hours and repair parts. This has the remarkable effect of preventing a reduction in the life of the wheel bearing.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of a vehicle equipped with an automotive wheel bearing of this invention, and Figure 2 is a comparison diagram of lithium soap-based grease and urea-based grease, showing the mixing consistency after a shell roll test. FIG. 3 is a graph showing changes over time in the hardness of grease during heating. Figure 4 is a graph showing the influence of viscosity in the fretting wear test of urea-based grease, Figure 5 is a graph showing the influence of consistency, and Figure 6 is a graph showing the influence of consistency.
The figure is a graph showing the amount of leakage versus mixing consistency of urea-based grease in the ASTM leakage test. U...Urea-based grease, 1...Wheel bearing, 2...Rolling element, 3...Outer ring, 4...Inner ring, 6
...Grease.

Claims (1)

[Scope of utility model registration request] For automobile wheel bearings in which rolling elements are interposed between the outer ring and the inner ring, this grease is a grease with a urea-based compound, polyurea or diurea, as a thickener and mineral oil as a base oil, and has a mixing consistency of 300 to 340. twenty five
An automobile wheel bearing characterized by containing grease having a base oil viscosity of 30 to 130cst/40℃ to prevent fretting and corrosion.