JP5891720B2 - Hub unit bearing - Google Patents

Description

  The present invention relates to a hub unit bearing provided in a vehicle or the like.

Conventionally, a hub unit bearing provided in a vehicle or the like, that is, a bearing in which a wheel side flange attached to a wheel side member and a vehicle body side flange attached to a vehicle body side member are integrated is described in, for example, Patent Documents 1 and 2. There is something.
Here, the wheel side member and the vehicle body side member are attached members to be attached to the flange. The wheel side member is, for example, a brake disc. The vehicle body side member is, for example, a knuckle connected to the subframe.
The hub unit bearing described in Patent Document 1 is obtained by press-fitting a steel raceway member between an outer ring provided with a vehicle body side flange and a rolling element. In addition, the hub unit bearing is lightened by making the outer ring aluminum.

JP 2006-153051 A

  However, in the hub unit bearing described in Patent Document 1, since the race member is made of steel and the outer ring is made of aluminum, the linear expansion coefficient of the race member and the linear expansion coefficient of the outer ring are different. Further, the positional relationship and shape between the race member and the outer ring are not set in consideration of the difference in linear expansion coefficient between the two.

For this reason, in the hub unit bearing described in Patent Literature 1, the temperature of the hub unit bearing rises due to heating by radiation / conduction heat from the brake disc, heat generation of the bearing itself accompanying rotation, When the temperature of the race member and the outer ring rises, the amount of deformation of the two differs due to the difference in the linear expansion coefficient between them, so that the change in the preload of the hub unit bearing at the time of temperature rise is large. This causes a problem that the rigidity, life, and torque of the hub unit bearing deteriorate.
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a hub unit bearing capable of suppressing a change in preload when the temperature rises.

In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention includes an inner annular member having a plurality of rows of inner rolling element raceway surfaces on an outer diameter surface,
An outer annular member having an inner diameter surface facing the outer diameter surface of the inner annular member;
An outer surface that is disposed between the inner annular member and the outer annular member in a state having a tightening margin between the inner annular surface of the outer annular member and that faces the raceways of the plurality of inner rolling elements. Two annular race members each having a rolling element raceway surface;
A plurality of rolling element raceways formed between the outer rolling element raceway surface and the inner rolling element raceway surface are movably loaded, and the outer rolling element raceway surface and the inward direction A plurality of rolling elements in contact with the rolling element raceway surface at an angular contact;
The two track portions Zaido officer, close in the direction in which the rolling element and the portion in contact with the rolling element raceways direction along the width direction of the width direction of the rolling element raceways,
It said outer annular member has a Rusotokata member side protrusion issuing collision toward the radially outer surface of the inner annular member between each track member fit Ri next,
Between each track member and the outer member side convex portion, an expansion adjustment spacer member formed of a material having a larger linear expansion coefficient than the outer annular member is disposed,
Material of the outer annular member, the linear expansion coefficient than the material of the raceway member is rather large, further, interference between the raceway member and the outer annular member in an environment of a first preset temperature Is generated and the inner ring surface of the outer annular member presses the outer surface of the raceway member, and the outer annular member and the above-mentioned in an environment of a preset second temperature that is higher than the first temperature. It is a material that creates a gap with the raceway member,
The material of the raceway member has a tightening margin between the outer annular member and the raceway member in the environment of the first temperature, and the inner diameter surface of the outer annular member presses the outer diameter surface of the raceway member. And a material in which a gap is generated between the outer annular member and the raceway member under the environment of the second temperature,
In an environment below the second temperature, the amount of preload in the contact angle direction of the rolling element raceway decreases as the temperature increases, and in an environment exceeding the second temperature, the rolling element raceway increases as the temperature increases. in which preload of the contact angle direction is characterized that you increase.

According to the present invention, in a hub unit bearing having a rolling element raceway having a double-row angular structure, the outer annular member protrudes toward the outer diameter surface of the inner annular member between adjacent race members, and the rolling element raceway It has an outward member side convex part which contacts the track member adjacent in the direction along the width direction of a road. In addition to this, a material having a larger linear expansion coefficient than the material of the raceway member is used as the material of the outer annular member.
Further, according to the present invention, under an environment of a first temperature set in advance, a tightening margin is generated between the outer annular member and the race member, and the inner diameter surface of the outer annular member is the outer diameter surface of the race member. Press. In addition, a gap is generated between the outer annular member and the raceway member under an environment of a preset second temperature that is higher than the first temperature.
Further, according to the present invention, an expansion adjusting spacer member made of a material having a linear expansion coefficient larger than that of the outer annular member is disposed between the race member and the outer member side convex portion. That is, the expansion adjusting spacer member is inserted between the race member and the outer member side convex portion so as to be in contact with the race member and the outer member side convex portion.

  For this reason, when the temperature of the hub unit bearing rises, the expansion amount of the outer annular member including the outer member side convex portion becomes larger than the expansion amount of the race member. As a result, the interference between the race member and the inner diameter surface of the outer annular member is reduced, and the preload in the radial direction of the rolling element raceway generated in the hub unit bearing is reduced. In addition to this, the degree of pressing of the track member by the outer member-side convex portion increases, and the preload in the direction along the width direction of the rolling element track is increased in the hub unit bearing.

Further, the outer annular member is formed of a material having a larger linear expansion coefficient than the race member. For example, the material of the race member is steel, and further, a material having a greater linear expansion coefficient than steel and a lower specific gravity, such as aluminum. Is used as the material of the outer ring member, so that the preload in the radial direction of the rolling element raceway is reduced and the preload in the width direction of the rolling element raceway is reduced when the temperature of the hub unit bearing rises. An increase can be effectively generated.
Further, when the temperature of the hub unit bearing rises from the first temperature environment to the second temperature environment, a gap is generated between the outer annular member and the race member, and the inner diameter of the outer annular member is increased. Even if the surface does not press the outer diameter surface of the race member and the temperature of the hub unit bearing rises, the preload in the radial direction of the rolling element raceway generated in the hub unit bearing does not decrease.
Further, when the temperature of the hub unit bearing rises, the expansion amount of the expansion adjustment spacer member becomes larger than the expansion amount of the outer annular member including the outer member-side convex portion. As a result, the degree of pressing of the outer member-side convex portion and the raceway member by the expansion adjustment spacer member increases, and the preload in the direction along the width direction of the rolling element raceway increases in the hub unit bearing. .

According to the present invention, in a hub unit bearing provided with a rolling element raceway of a double row angular structure, the preload in the radial direction of the rolling element raceway that occurs in the hub unit bearing when the temperature rises is reduced, and the rolling element It is possible to increase the preload in the direction along the width direction of the track. In addition to this, the material of the outer annular member is a material having a larger linear expansion coefficient than the material of the raceway member.
For this reason, when the temperature rises, the change in the preload in the radial direction of the rolling element raceway and the change in the preload in the direction along the width direction of the rolling element raceway are offset to suppress the change in the preload in the contact angle direction. It is possible to provide a hub unit bearing that can be used.

It is sectional drawing which shows the structure of the hub unit bearing of 1st embodiment of this invention. It is a figure which shows the relationship between the usage environment temperature of a hub unit bearing, and the variation | change_quantity of the preload to the radial direction of a rolling element track according to the change of a usage environment temperature. It is a figure which shows the relationship between the use environment temperature of a hub unit bearing, and the variation | change_quantity of the preload to the direction along the width direction of a rolling element track path accompanying the change of a use environment temperature. It is a figure which shows the relationship between the use environment temperature of a hub unit bearing, and the variation | change_quantity of the preload of the contact angle direction accompanying the change of a use environment temperature. It is sectional drawing which shows the structure of the hub unit bearing of 2nd embodiment of this invention. It is a figure which shows the relationship between the use environment temperature of a hub unit bearing, and the variation | change_quantity of the preload of the contact angle direction accompanying the change of a use environment temperature.

(First embodiment)
Hereinafter, a first embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings.
(Constitution)
First, the configuration of the hub unit bearing will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing the configuration of the hub unit bearing 1 of the present embodiment.
As shown in FIG. 1, the hub unit bearing 1 includes an inner annular member 2, an outer annular member 4, two raceway members 6 a and 6 b, and a plurality of rolling elements 8. The hub unit bearing 1 of the present embodiment is a bearing provided in a vehicle, in which a wheel side flange to which a wheel side member is attached and a vehicle body side flange to be attached to the vehicle body side member are integrated. In this embodiment, as an example, the wheel side member is a brake disk and a wheel (not shown), and the vehicle body side member is a knuckle (not shown) connected to a subframe (not shown).

The inner annular member 2 includes a hub 10, an inner flange 12, and an inner raceway surface forming member 14.
The hub 10 is formed in an annular shape, and has an inner rolling element raceway surface 16a on the outer diameter surface thereof.
In the present embodiment, a case where the hub 10 is formed using steel (bearing steel or the like) will be described.
The inner rolling member raceway surface 16 a is formed over the entire circumferential direction of the inner annular member 2 on the outer diameter surface of the inner annular member 2.
The inner flange 12 is formed integrally with the hub 10 on the outer diameter surface of the hub 10, and is disposed at the end of the inner annular member 2 on the wheel (not shown) side.
Here, the inner flange 12 is a flange to which a brake disc and a wheel are attached. The brake disc is a member to be attached to which the inner annular member 2 is attached.

Further, an inner fastening member insertion hole 20 through which the fastening member 18 is inserted is formed in the inner flange 12. The inner fastening member insertion hole 20 is formed through the inner flange 12.
The inner raceway surface forming member 14 is formed in an annular shape, and is attached to the vehicle body (not shown) side of the inner annular member 2.
The inner raceway surface forming member 14 has an inner rolling member raceway surface 16b on the outer diameter surface thereof.

The inner rolling element raceway surface 16 b is formed on the outer diameter surface of the inner raceway surface forming member 14 over the entire circumferential direction of the inner raceway surface forming member 14.
Therefore, the inner annular member 2 has two rows (a plurality of rows) of inner rolling member raceway surfaces 16a and 16b with the inner raceway surface forming member 14 attached.
The outer annular member 4 is formed in an annular shape by casting or forging, and the inner diameter surface thereof faces the outer diameter surface of the inner annular member 2.

Further, an outer flange 22 to be attached to the knuckle is formed on the outer diameter surface of the outer annular member 4.
Here, the knuckle is a member to be attached to which the outer annular member 4 is attached. Four outer flanges 22 are formed on the outer diameter surface of the outer annular member 4. In this embodiment, the knuckle and the outer annular member 4 are separated from each other. However, the present invention is not limited to this, and the knuckle and the outer annular member 4 may be integrally formed.

Similar to the inner flange 12, an outer fastening member insertion hole 24 through which a fastening member is inserted is formed in the outer flange 22. The outer fastening member insertion hole 24 is formed by penetrating the outer flange 22.
Further, the outer flange 22 is formed so that the outer diameter of the portion of the outer annular member 4 that forms the outer flange 22 is larger than that of the other portions. That is, the outer flange 22 protrudes from the other parts of the outer annular member 4.

The outer annular member 4 has an outer member-side convex portion 26 projecting radially inward toward the outer diameter surface of the inner annular member 2 on the inner diameter surface of the outer annular member 4. The protruding amount of the outer member side convex portion 26 is such that there is a gap across the entire circumferential direction of the inner annular member 2 between the outer member side convex portion 26 and the outer diameter surface of the inner annular member 2. Set to the value to be formed.
The outer member-side convex portion 26 is formed over the entire circumferential direction of the outer annular member 4 on the inner diameter surface of the outer annular member 4.

The two track members 6 a and 6 b are formed in an annular shape, and have a margin between the inner ring surface of the outer annular member 4 and the inner annular member 2 and the outer annular member 4. Has been placed. That is, the two track members 6 a and 6 b are press-fitted into the inner surface side of the outer annular member 4.
Here, when the outer annular member 4 is formed by casting, the race members 6a and 6b are not press-fitted into the inner diameter surface side of the outer annular member 4, and the race member 6a is introduced into the inner diameter surface side of the outer annular member 4. , 6b, the raceway members 6a, 6b are disposed between the inner annular member 2 and the outer annular member 4 in a state of having a tightening margin between the inner ring surface of the outer annular member 4. May be.

On the other hand, when the outer annular member 4 is formed by forging, a fitting portion (not shown) is formed in the outer annular member 4 by machining, and then the race members 6a and 6b are press-fitted into the fitting portion. Accordingly, the raceway members 6 a and 6 b may be disposed between the inner annular member 2 and the outer annular member 4 in a state having a fastening allowance between the inner circumferential surface of the outer annular member 4.
The track member 6a has an outer rolling element raceway surface 28a facing the inner rolling element raceway face 16a on the inner diameter surface thereof.

The outer rolling element raceway surface 28a is formed over the entire circumferential direction of the raceway member 6a on the inner diameter surface of the raceway member 6a.
The track member 6b is disposed on the vehicle body side of the track member 6a, and has an outer rolling member track surface 28b facing the inner rolling member track surface 16b on the inner diameter surface thereof.
The outer rolling element raceway surface 28b is formed over the entire circumferential direction of the raceway member 6b on the inner diameter surface of the raceway member 6b.
Accordingly, the two track members 6a and 6b are disposed between the inner annular member 2 and the outer annular member 4 in a state having a tightening allowance between the inner ring surface and the inner annular surface of the outer annular member 4. The outer rolling element raceway surfaces 28a and 28b are opposed to the two rows of inner rolling element raceway surfaces 16a and 16b, respectively.

  Further, the raceway member 6a and the raceway member 6b are respectively rolling element raceway paths formed between the two rows of outer raceway raceway surfaces 28a, 28b and the two rows of inner raceway raceway surfaces 16a, 16b. It is in contact with the outer member side convex portion 26 in a direction along the width direction. That is, the outer member-side convex portion 26 is sandwiched between the raceway member 6a and the raceway member 6b from the direction along the width direction of the rolling element raceway. In FIG. 1, the radial direction of the inner annular member 2 and the rolling element raceway is indicated as “radial direction” by a bidirectional arrow, and the direction along the width direction of the rolling element raceway is indicated by a bidirectional arrow. “Axial direction” is shown.

  The raceway members 6a and 6b may be subjected to polishing and superfinishing of the outer rolling member raceway surface 28 before being press-fitted into the inner surface side of the outer annular member 4. However, preferably, after the raceway members 6a and 6b are heat-treated, the raceway members 6a and 6b are pressed into the inner surface side of the outer annular member 4 to be integrated and polished, superfinished, etc. Perform precision machining. This makes it possible to improve the accuracy during assembly as compared with the case where the outer rolling member raceway surfaces 28a and 28b are polished and superfinished before being press-fitted into the inner surface of the outer annular member 4. It is to become.

Each rolling element 8 is formed of, for example, a steel ball (ball), and the outer rolling element raceway surface 28a and the inner rolling element raceway surface 16a, and the outer rolling element raceway surface 28b and the inner rolling element, respectively. In a state where it contacts the raceway surface 16b with an angular contact, it is slidably loaded into the rolling element raceway.
Further, the track members 6a and 6b, that is, the two adjacent track members 6a and 6b are in contact with the rolling element 8 in the direction along the width direction of the rolling element track (the outer diameter of the inner annular member 2). The portion protruding toward the surface is close in the direction along the width direction of the rolling element raceway.

Therefore, the hub unit bearing 1 of the present embodiment is a double row angular contact ball bearing (backside combination [DB] angular) in which two rows of rolling element raceways are combined on the backside with the outer member side convex portion 26 interposed therebetween. Ball bearing).
Further, the outer member side convex portion 26 protrudes toward the outer diameter surface of the inner annular member 2 between the adjacent track members 6a and 6b, and in a direction along the width direction of the rolling element track path. The track members 6a and 6b are in contact with each other.
Moreover, the rolling element holder | retainer 30 is arrange | positioned between the adjacent rolling elements 8 along the circumferential direction of the outer annular member 4 and the inner annular member 2, respectively.
Although not particularly illustrated, a lubricant such as grease is disposed between the outer annular member 4 and the inner annular member 2 together with the rolling element 8 and the rolling element holder 30.

(Material of outer annular member 4 and material of raceway members 6a and 6b)
Hereinafter, the material for forming the outer annular member 4 and the material for forming the race members 6a and 6b will be described with reference to FIG. 1 and FIG.
The material of the outer annular member 4 is a material having a larger linear expansion coefficient than the material of the raceway members 6a and 6b.
Here, the linear expansion coefficient (also referred to as a linear expansion coefficient) is a ratio between the increase in the length of the substance and the original length when the temperature is raised by 1 degree Celsius.

In the present embodiment, as an example, a case where the outer annular member 4 is formed of an aluminum alloy will be described.
In connection with this, this embodiment demonstrates the case where track member 6a, 6b is formed using steel (bearing steel etc.) which is a material whose coefficient of linear expansion is smaller than an aluminum alloy.
Further, the material of the outer annular member 4 and the material of the raceway members 6a and 6b are subjected to a tightening margin between the outer annular member 4 and the raceway member 6 in a preset first temperature environment. The inner ring surface of the outer annular member 4 is made of a material that presses the outer diameter surfaces of the track members 6a and 6b.
In addition to this, the material of the outer annular member 4 and the material of the race members 6a and 6b are the outer annular member 4 and the race members 6a in an environment of a preset second temperature that is higher than the first temperature. , 6b is a material that generates a gap.

In the present embodiment, as an example, the first temperature is 20 [° C.] (normal temperature).
Further, in the present embodiment, as an example, the second temperature is generated in a state where the race members 6a and 6b are press-fitted into the inner surface side of the outer annular member 4 as shown in FIG. 4 and the track members 6a and 6b (in the following description, there are cases where it is described as “initial press-fit tightening allowance”) values (about 50 [° C.], about 85 [° C.], About 125 [° C.]). FIG. 2 is a diagram showing the relationship between the use environment temperature of the hub unit bearing 1 and the amount of change in the preload in the radial direction of the rolling element raceway along with the change in the use environment temperature. In FIG. 2, the horizontal axis indicates the operating environment temperature of the hub unit bearing 1 (in the drawing, “temperature [° C.]”), and the vertical axis indicates the rotation accompanying the change in the operating environment temperature. The amount of change in the preload in the radial direction of the moving body track (denoted as “preload change amount” in the figure) is shown.

  In addition, as a calculation method of a preload, it is possible to use FEM (Finite Element Method) and general fitting calculation. Parameters used for calculating the preload include temperature, outer diameter / inner diameter / elastic modulus / linear expansion coefficient of the outer annular member 4, outer diameter / inner diameter / elastic modulus / linear expansion coefficient of the track members 6a and 6b, It is possible to use the initial press-fitting allowance, the length of the outer member-side convex portion 26, the linear expansion coefficient, and the like.

  As shown in FIG. 2, in the hub unit bearing 1, the preload in the radial direction of the rolling element raceway decreases as the temperature rises. Under the environment of the first temperature or lower, the interference generated between the outer annular member 4 and the race members 6a and 6b becomes larger than “0”, and the outer annular member 4 and the race members 6a and 6b. A minus gap is generated between That is, in the environment below the first temperature, in the hub unit bearing 1, the preload in the radial direction of the inner annular member 2 (indicated by a broken line in FIG. 2) is “± 0” or more.

  In addition, when the initial press-fitting allowance is small (in the figure, indicated as “tightening allowance”), when the temperature of the hub unit bearing 1 rises and the use environment temperature becomes about 50 [° C.], The tightening margin is “0” (in the figure, described as “the point at which the tightening margin is zero”). As a result, the interference generated between the outer annular member 4 and the race members 6a and 6b is larger than “0”, and a gap is generated between the outer annular member 4 and the race members 6a and 6b. It becomes a state.

  If the initial press-fitting allowance is small, the expansion amount of the race members 6a and 6b is larger than the expansion amount of the inner annular member 2 when the use environment temperature is about 50 [° C.] or less. Although the preload in the radial direction of the rolling element raceway decreases, when the operating environment temperature exceeds about 50 [° C.], the expansion amount of the track members 6a and 6b becomes equal to the expansion amount of the inner annular member 2, and the rolling The decrease of the preload in the radial direction of the moving body track is stopped, and the preload in the radial direction of the rolling body track is not changed.

  In addition, when the initial press-fit tightening margin is larger than the above-described case of “tightening margin” (indicated in the figure as “tightening margin”), the temperature of the hub unit bearing 1 rises and the operating environment temperature Is in an environment of about 85 [° C.], the tightening margin becomes “0”. As a result, the interference generated between the outer annular member 4 and the race members 6a and 6b is larger than “0”, and a gap is generated between the outer annular member 4 and the race members 6a and 6b. It becomes a state.

  That is, when the initial press-fit tightening allowance is larger than the above-described case of “tightening allowance small”, the expansion amount of the race members 6a and 6b is less than that of the inner annular member 2 when the use environment temperature is about 85 [° C.] or less. Since it is larger than the expansion amount, the preload in the radial direction of the rolling element raceway decreases as the temperature rises. However, when the operating environment temperature exceeds about 85 [° C.], the expansion amount of the raceway members 6a and 6b increases. It becomes equal to the expansion amount of the annular member 2, and the decrease in the preload in the radial direction of the rolling element raceway is stopped, and the preload in the radial direction of the rolling element raceway is not changed.

  In addition, when the initial press-fit tightening allowance is larger than the above-described case of “tightening allowance” (indicated in the figure as “tightening allowance”), the temperature of the hub unit bearing 1 increases, and the operating environment temperature Is in an environment of about 125 [° C.], the tightening margin becomes “0”. As a result, the interference generated between the outer annular member 4 and the race members 6a and 6b is larger than “0”, and a gap is generated between the outer annular member 4 and the race members 6a and 6b. It becomes a state.

  That is, when the initial press-fit tightening allowance is larger than the above-mentioned “tightening allowance”, the expansion amount of the race members 6a and 6b is less than that of the inner annular member 2 when the use environment temperature is about 125 [° C.] or less. Since the amount of expansion is larger than the amount of expansion, the preload in the radial direction of the rolling element raceway decreases as the temperature rises. However, when the operating environment temperature exceeds about 125 [° C.], the amount of expansion of the track members 6a and 6b increases. It becomes equal to the expansion amount of the annular member 2, and the decrease in the preload in the radial direction of the rolling element raceway is stopped, and the preload in the radial direction of the rolling element raceway is not changed.

As described above, the second temperature is generated in a state where the race members 6a and 6b are press-fitted to the inner surface side of the outer annular member 4, and the tightening margin between the outer annular member 4 and the race members 6a and 6b is large. The higher the temperature.
Therefore, when the initial press-fitting allowance is the above-described “small tightening allowance”, that is, when the initial press-fit tightening allowance is small, the outer annular member is placed in a relatively low temperature environment (about 50 ° C.). 4 and the raceway members 6a and 6b are larger than “0”, and even when the hub unit bearing 1 is at a high temperature, the preload in the radial direction of the rolling element raceway does not change. Become.

  On the other hand, when the initial press-fitting allowance is “medium tightening allowance” or “large tightening allowance” as described above, that is, when the initial press-fit tightening allowance is large, The interference generated between the annular member 4 and the raceway members 6a and 6b does not become larger than “0”, and the rolling element raceway is changed to a relatively high temperature (about 85 [° C], about 125 [° C]). The preload in the radial direction is reduced.

(Function)
Next, the operation of the hub unit bearing 1 will be described with reference to FIGS. 1 and 2 and FIGS. 3 and 4.
When the hub unit bearing 1 is used, for example, heating by radiation / conduction heat from the brake disc and components of the hub unit bearing 1, that is, the inner annular member 2, the outer annular member 4, and the race members 6a and 6b are used. The temperature of the hub unit bearing 1 rises due to the heat generated by the rolling elements 8.
The temperature at which the hub unit bearing 1 is used is generally in the range of −40 [° C.] to 120 [° C.].

  Here, in the hub unit bearing 1 of the present embodiment, the material of the outer annular member 4 is a material having a larger linear expansion coefficient than the material of the race members 6a and 6b. In addition to this, the outer annular member 4 projects toward the outer diameter surface of the inner annular member 2 between the adjacent track members 6a and 6b, and is adjacent to the track along the width direction of the rolling element track. It has the outward member side convex part 26 which contacts member 6a, 6b.

For this reason, when the temperature of the hub unit bearing 1 rises, the expansion amount of the outer annular member 4 including the outer member-side convex portion 26 becomes larger than the expansion amounts of the race members 6a and 6b.
Further, in the hub unit bearing 1 of the present embodiment, under the environment of the first temperature (20 [° C.]), a tightening margin is generated between the outer annular member 4 and the raceway member 6, and the outer annular member. The inner diameter surface of 4 presses the outer diameter surfaces of the track members 6a and 6b.

On the other hand, when the temperature of the hub unit bearing 1 rises to be in the environment of the second temperature (about 50, 85, 125 [° C.]), the race members 6a, 6b that are reduced in diameter when pressed into the outer annular member 4 are used. Is expanded, and a gap is generated between the outer annular member 4 and the track members 6a and 6b.
Thereby, when the temperature of the hub unit bearing 1 rises, the degree of pressing of the outer diameter surfaces of the race members 6a and 6b by the inner diameter surface of the outer annular member 4 decreases, and the rolling element raceway generated in the hub unit bearing 1 The preload in the radial direction is reduced (see FIG. 2).

  Further, the outer member-side convex portion 26 is sandwiched between the raceway member 6a and the raceway member 6b from the direction along the width direction of the rolling element raceway, and includes an outer member-side convex portion 26. The material No. 4 is a material (aluminum alloy) having a larger linear expansion coefficient than the material (steel) of the hub 10. For this reason, when the temperature of the hub unit bearing 1 rises, the expansion amount of the outer member side convex portion 26 is such that the outer member side convex portion 26 and the inner annular member 2 of the inner annular member 2 (hub 10) are expanded. The amount of expansion of the portions facing each other in the radial direction is larger, and the degree of pressing of the track members 6a and 6b in the direction along the width direction of the rolling element track is increased.

As a result, as shown in FIG. 3, as the temperature of the hub unit bearing 1 rises, the preload generated in the hub unit bearing 1 in the direction along the width direction of the rolling element raceway increases.
FIG. 3 is a diagram showing the relationship between the use environment temperature of the hub unit bearing 1 and the amount of change in the preload in the direction along the width direction of the rolling element raceway due to the change in the use environment temperature. In FIG. 3, the horizontal axis indicates the operating environment temperature of the hub unit bearing 1 (indicated as “temperature [° C.]” in the figure), and the vertical axis indicates the rotation accompanying the change in the operating environment temperature. The amount of change in preload in the direction along the width direction of the moving body track (denoted as “preload change amount” in the figure) is shown. In FIG. 3, the preload in the direction along the width direction of the rolling element raceway generated in the hub unit bearing 1 is indicated by a broken line.

Therefore, when the temperature of the hub unit bearing 1 rises, the preload in the radial direction of the rolling element raceway generated in the hub unit bearing 1 is reduced, and in the width direction of the rolling element raceway generated in the hub unit bearing 1. The preload in the direction along is increased.
In the present embodiment, as shown in FIGS. 2 and 3, the degree of reduction in the preload in the radial direction of the rolling element raceway that occurs in the hub unit bearing 1 as the temperature of the hub unit bearing 1 increases ( The degree of increase in the preload in the direction along the width direction of the rolling element raceway (the degree of inclination of the broken line in FIG. 3) is smaller than the degree of inclination of the broken line in FIG. This is set, for example, by adjusting the shape or the like of the outward member side convex portion 26.

Therefore, as shown in FIG. 4, when the initial press-fitting allowance is small (in the figure, indicated as “tightening allowance”), when the temperature of the hub unit bearing 1 rises, the operating environment temperature is about 50 [° C. In the following, the degree of change in the preload generated in the hub unit bearing 1 when the temperature of the hub unit bearing 1 rises becomes the degree of change in which the preload decreases as the temperature of the hub unit bearing 1 rises.
When the initial press-fitting allowance is small and the operating environment temperature exceeds about 50 ° C., the degree of change in the preload generated in the hub unit bearing 1 when the temperature of the hub unit bearing 1 rises is The degree of change is such that the preload increases as the temperature rises.

  As shown in FIG. 4, when the initial press-fitting allowance is larger than the above-described case of “tightening allowance” (shown as “tightening allowance” in the figure), the temperature of the hub unit bearing 1 When the operating environment temperature is about 85 [° C.] or less when the temperature rises, the degree of change in the preload generated in the hub unit bearing 1 when the temperature of the hub unit bearing 1 rises decreases as the temperature of the hub unit bearing 1 increases. The degree of change.

If the initial press-fit tightening allowance is larger than the above-described “small tightening allowance”, when the operating environment temperature exceeds about 85 ° C., the hub unit bearing 1 is generated when the temperature of the hub unit bearing 1 rises. The degree of change in the preload is a degree of change in which the preload increases as the temperature of the hub unit bearing 1 increases.
In addition, as shown in FIG. 4, when the initial press-fitting allowance is larger than the above-described case of “tightening allowance” (shown as “tightening allowance” in the figure), the temperature of the hub unit bearing 1 When the operating environment temperature is about 125 [° C.] or less when the temperature rises, the degree of change in the preload generated in the hub unit bearing 1 when the temperature of the hub unit bearing 1 rises decreases as the temperature of the hub unit bearing 1 increases. The degree of change.

If the initial press-fit tightening allowance is larger than that of the above-described “tightening allowance”, the operating temperature of the hub unit bearing 1 is increased when the temperature of the hub unit bearing 1 rises when the operating environment temperature exceeds about 125 [° C.]. The degree of change in the preload is a degree of change in which the preload increases as the temperature of the hub unit bearing 1 increases.
FIG. 4 is a diagram showing the relationship between the use environment temperature of the hub unit bearing 1 and the amount of change in the preload in the contact angle direction accompanying the change in the use environment temperature. In FIG. 4, the horizontal axis indicates the operating environment temperature of the hub unit bearing 1 (in the drawing, “temperature [° C.]”), and the vertical axis indicates the contact angle accompanying the change in the operating environment temperature. The amount of change in the preload in the direction (denoted as “preload change amount” in the figure) is shown.

Here, the degree of change in the preload in the contact angle direction that occurs in the hub unit bearing 1 when the temperature of the hub unit bearing 1 rises as shown in FIG. 4 is the change in the preload in the radial direction of the rolling element raceway. It is a value obtained by combining the degree and the degree of change in the direction along the width direction of the rolling element raceway.
The contact angle direction refers to, for example, the angle at which the outer rolling element raceway surface 28a is inclined with respect to the central axis of the raceway member 6a, and the outer rolling element raceway surface 28b with respect to the central axis of the raceway member 6b. It is an angle that is inclined.

The preload in the contact angle direction is a pressure applied to the rolling element 8 by the inner rolling element raceway surfaces 16a and 16b and the outer rolling element raceway surfaces 28a and 28b. It is a value corresponding to a change in relative distance between the rolling element raceway surface 28a and a change in relative distance between the inner rolling element raceway surface 16b and the outer rolling element raceway surface 28b.
In FIG. 4, as in FIG. 2, the temperature at which the tightening margin is “0” is described as “the point at which the tightening margin is zero”.
Therefore, as shown in FIG. 4, when the initial press-fitting allowance is set small, the outer annular member 4 and the raceway members 6a and 6b are placed in a relatively low temperature environment (about 50 [° C.]). By making the generated allowance larger than “0”, it is possible to suppress the change in the preload of the hub unit bearing 1.

(Effects of the first embodiment)
The effects of this embodiment are listed below.
(1) In the hub unit bearing 1 of the present embodiment, in the hub unit bearing 1 having a rolling element raceway of a double row angular structure, the outer annular member 4 is an inner annular member between adjacent raceway members 6a and 6b. 2 has an outer member-side convex portion 26 that protrudes toward the outer diameter surface 2 and contacts the adjacent track members 6a and 6b in the direction along the width direction of the rolling element track. In addition to this, as the material of the outer annular member 4, a material having a larger linear expansion coefficient than the material of the race members 6a and 6b is used.

For this reason, when the temperature of the hub unit bearing 1 rises, the expansion amount of the outer annular member 4 including the outer member-side convex portion 26 becomes larger than the expansion amounts of the race members 6a and 6b.
Thereby, when the temperature of the hub unit bearing 1 rises, the interference between the race members 6a and 6b and the inner diameter surface of the outer annular member 4 decreases, and the radial direction of the rolling element raceway generated in the hub unit bearing 1 The preload to the is reduced. In addition to this, the degree of pressing of the race members 6a and 6b by the outer member side convex portion 26 increases, and the preload generated in the hub unit bearing 1 in the direction along the width direction of the rolling element raceway increases. .

For this reason, when the temperature of the hub unit bearing 1 rises, it is possible to cancel out the change in the preload in the radial direction of the rolling element raceway and the change in the preload in the direction along the width direction of the rolling element raceway. It becomes possible to suppress a change in the preload in the angular direction.
Further, the outer annular member 4 is formed of a material having a larger linear expansion coefficient than the race members 6a and 6b, thereby reducing the preload in the radial direction of the rolling element raceway when the temperature of the hub unit bearing 1 is increased. The increase in preload in the direction along the width direction of the rolling element raceway can be effectively generated.
As a result, it is possible to provide the hub unit bearing 1 capable of suppressing a change in preload when the temperature rises.

(2) In the hub unit bearing 1 of the present embodiment, under the environment of the first temperature set in advance, a tightening margin is generated between the outer annular member 4 and the race members 6a and 6b, and the outer annular member. The inner diameter surface of 4 presses the outer diameter surfaces of the track members 6a and 6b. Further, a gap is generated between the outer annular member 4 and the track members 6a and 6b under an environment of a preset second temperature that is higher than the first temperature.

  For this reason, when the temperature of the hub unit bearing 1 rises from the environment of the first temperature and becomes the environment of the second temperature, a gap is generated between the outer annular member 4 and the race members 6a and 6b, Even if the inner diameter surface of the outer annular member 4 does not press the outer diameter surfaces of the raceway members 6a and 6b and the temperature of the hub unit bearing 1 rises, the inner annular member generated in the hub unit bearing 1 The preload in the radial direction of 2 does not decrease.

  As a result, a tightening margin is generated between the outer annular member 4 and the race members 6a and 6b in the environment of the first temperature, so that the race members 6a and 6b are press-fitted into the inner surface side of the outer annular member 4. It is possible to perform machining positioning, which is a process performed after the process. This is because the tightening margin between the outer annular member 4 and the race members 6a and 6b is "0" or less in the environment of the first temperature, and between the outer annular member 4 and the race members 6a and 6b. This is because, when the gap is generated, it is impossible to perform machining positioning when the hub unit bearing 1 is manufactured.

(3) In the hub unit bearing 1 of the present embodiment, the material of the outer annular member 4 is a material having a larger linear expansion coefficient than the material of the race members 6a and 6b, and has a larger volume than the race members 6a and 6b. The outer annular member 4 is formed of a material having a specific gravity smaller than that of the track members 6a and 6b.
As a result, for example, the hub unit bearing 1 is compared with the case where the outer annular member 4 having a larger volume than the race members 6a and 6b is formed of a material having a specific gravity greater than that of the race members 6a and 6b. It is possible to reduce the weight.

(Modification)
Hereinafter, modifications of the present embodiment will be listed.
(1) In the hub unit bearing 1 of the present embodiment, the outer annular member 4 is made of an aluminum alloy, and the race members 6a and 6b are made of steel (bearing) having a smaller linear expansion coefficient than the aluminum alloy. However, the material of the outer annular member 4 and the material of the race members 6a and 6b are not limited to this. In short, the material of the outer annular member 4 may be a material having a larger linear expansion coefficient than the material of the raceway members 6a and 6b. In particular, if the ratio of the linear expansion coefficient of the track members 6a and 6b to the linear expansion coefficient of the outer annular member 4 is 0.8 or less (material of the track members 6a and 6b / material of the outer annular member 4), It is suitable for suppressing a change in preload when the temperature rises.

(2) In this embodiment, the rolling element 8 is a ball and the hub unit bearing 1 is an angular ball bearing. However, the present invention is not limited to this, and the rolling element 8 may be a tapered roller. In this case, the hub unit bearing 1 is a tapered roller bearing.
(3) In the present embodiment, the configuration of the hub unit bearing 1 is configured to include the rolling element cage 30, but is not limited thereto, and the configuration of the hub unit bearing 1 is not limited to the rolling element cage 30. It is good also as a structure which is not provided.

(4) In this embodiment, the attachment object of the inner annular member 2 is a brake disc (wheel side member) that is a rotating member, and the attachment object of the outer annular member 4 is a knuckle (vehicle body side member). However, the present invention is not limited to this, and the attachment target of the inner annular member 2 may be a knuckle and the attachment target of the outer annular member 4 may be a brake disk.

(Second embodiment)
Hereinafter, a second embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings.
(Constitution)
First, the configuration of the hub unit bearing of the present embodiment will be described using FIG. 5 with reference to FIG. In addition, the same code | symbol is attached | subjected about the structure similar to 1st embodiment mentioned above.
FIG. 5 is a cross-sectional view showing the configuration of the hub unit bearing 1 of the present embodiment.
As shown in FIG. 5, the hub unit bearing 1 includes an inner annular member 2, an outer annular member 4, two track members 6 a and 6 b, a plurality of rolling elements 8, and an expansion adjustment spacer member 32. It has. The hub unit bearing 1 of the present embodiment has the same configuration as that of the above-described first embodiment except that the expansion adjustment spacer member 32 is provided. Therefore, in the following description, the expansion adjustment spacer member will be described. The description regarding the configuration other than 32 may be omitted.

The expansion adjusting spacer member 32 is formed in an annular shape using a material having a linear expansion coefficient larger than that of the outer annular member 4 (made of an aluminum alloy) such as resin, for example. It arrange | positions between the direction member side convex parts 34. FIG.
The expansion adjusting spacer member 32 is formed in a shape that does not contact the inner annular member 2 in a state of being disposed between the track member 6b and the outer member-side convex portion 34.

Further, in the hub unit bearing 1 of the present embodiment, unlike the first embodiment described above, the material of the outer annular member 4 and the material of the race members 6a and 6b can be used even in the environment of the second temperature. A material in which a tightening margin is generated between the annular member 4 and the raceway member 6 is used.
Moreover, in the hub unit bearing 1 of this embodiment, the shape of the outward member side convex part 34 differs from the outward member side convex part 26 (refer FIG. 1) in the hub unit bearing 1 of 1st embodiment mentioned above. Yes.

Specifically, the length of the outer member-side convex portion 34 in the direction along the width direction of the rolling element raceway (indicated as “axial direction” by a bidirectional arrow in FIG. 5) is between expansion adjustments. The length of the seat member 32 in the direction along the width direction of the rolling element raceway is shorter than the outer member-side convex portion 26 of the first embodiment.
Other configurations are the same as those in the first embodiment described above, and thus the description thereof is omitted.

(Function)
Next, the operation of the hub unit bearing 1 will be described with reference to FIGS. 1 to 5 and FIG. In addition, about the effect | action similar to 1st embodiment mentioned above, the description may be abbreviate | omitted.
When the hub unit bearing 1 is used, for example, heating by radiation / conduction heat from the brake disc and components of the hub unit bearing 1, that is, the inner annular member 2, the outer annular member 4, and the race members 6a and 6b are used. The temperature of the hub unit bearing 1 rises due to the heat generated by the rolling elements 8.
Here, in the hub unit bearing 1 of the present embodiment, the expansion adjusting spacer member 32 is formed of a material having a larger linear expansion coefficient than the outer annular member 4.

For this reason, when the temperature of the hub unit bearing 1 rises, the expansion amount of the expansion adjustment spacer member 32 becomes larger than the expansion amount of the outer member side convex portion 34.
In the hub unit bearing 1 of the present embodiment, the expansion adjustment spacer member 32 is disposed between the raceway member 6b and the outer member-side convex portion 34. In other words, the expansion adjustment spacer member 32 is inserted between the raceway member 6b and the outer member side convex portion 34 in a state of being in contact with the raceway member 6b and the outer member side convex portion 34.

As a result, when the temperature of the hub unit bearing 1 rises and the expansion adjustment spacer member 32 and the outer member-side convex portion 34 expand, the rolling elements by the expansion adjustment spacer member 32 and the outer member-side convex portion 34. The degree of pressing of the track members 6a and 6b in the direction along the width direction of the track path increases.
Further, in the hub unit bearing 1 of the present embodiment, the material of the outer annular member 4 and the material of the race members 6a and 6b are the same as those of the outer annular member 4 and the race members 6a, 6b even under the second temperature environment. 6b is a material that generates a tightening allowance.

Therefore, in the hub unit bearing 1 of the present embodiment, as compared with the first embodiment described above, as the temperature of the hub unit bearing 1 increases, along the width direction of the rolling element raceway generated in the hub unit bearing 1. The degree of increase of the preload in the selected direction (see FIG. 3) increases.
Thereby, in the hub unit bearing 1 of the present embodiment, unlike the first embodiment described above, the preload in the radial direction of the rolling element raceway decreases when the temperature of the hub unit bearing 1 increases, and the rolling element raceway When the preload in the direction along the width direction of the roller increases, the degree of decrease in the preload in the radial direction of the rolling element raceway generated in the hub unit bearing 1 as the temperature of the hub unit bearing 1 increases (see FIG. 2) And the increase degree (refer FIG. 3) of the preload to the direction along the width direction of a rolling element track becomes an approximate value.

  As described above, in the hub unit bearing 1 of the present embodiment, when the temperature of the hub unit bearing 1 increases, even if the temperature of the hub unit bearing 1 increases as shown in FIG. The angular preload does not change at “± 0”. When the temperature of the hub unit bearing 1 exceeds the second temperature, the decrease in the preload in the radial direction of the rolling element raceway stops and the increase in the preload in the direction along the width direction of the rolling element raceway. In order to continue, the preload in the contact angle direction increases as the temperature rises from the second temperature.

Specifically, as shown in FIG. 6, when the initial press-fit tightening allowance is small (in the figure, indicated as “tightening allowance”), the operating environment temperature is about 50 when the temperature of the hub unit bearing 1 rises. Below [° C.], even if the temperature of the hub unit bearing 1 rises, the preload in the contact angle direction does not change at “± 0”.
If the initial press-fitting allowance is small and the operating environment temperature exceeds about 50 [° C.], the preload in the contact angle direction increases as the temperature of the hub unit bearing 1 increases.

In addition, as shown in FIG. 6, when the initial press-fitting allowance is larger than the above-described “tightening allowance” (in the figure, indicated as “tightening allowance”), the temperature of the hub unit bearing 1 When the operating environment temperature is about 85 [° C.] or less, the preload in the contact angle direction does not change at “± 0” even when the temperature of the hub unit bearing 1 increases.
If the initial press-fit tightening allowance is larger than the above-described “small tightening allowance” and the operating environment temperature exceeds about 85 [° C.], the temperature of the hub unit bearing 1 increases with the increase in the temperature of the hub unit bearing 1. Preload increases.

In addition, as shown in FIG. 6, when the initial press-fitting allowance is larger than the case of the “tightening allowance” described above (shown as “tightening allowance” in the figure), the temperature of the hub unit bearing 1 When the operating environment temperature is about 125 [° C.] or less, the preload in the contact angle direction does not change to “± 0” even when the temperature of the hub unit bearing 1 increases.
When the initial press-fit tightening allowance is larger than the above-described case of “tightening allowance”, when the operating environment temperature exceeds about 125 [° C.], the temperature of the hub unit bearing 1 increases, Preload increases.

  Therefore, as shown in FIG. 6, if the initial press-fitting allowance is set to be larger than that in the above-described “intermittent allowance”, the upper limit value of the general temperature range in which the hub unit bearing 1 is used is 120. Since the preload in the contact angle direction does not change at “± 0” until the temperature of the hub unit bearing 1 rises to a temperature higher than [° C.] (about 125 [° C.]), the change in the preload of the hub unit bearing 1 Can be suppressed.

  That is, if the initial press-fit tightening allowance is set to be larger than that of the above-described “tightening allowance”, the preload in the contact angle direction is “± 0” within the general temperature range in which the hub unit bearing 1 is used. Since it does not change, the effect of suppressing the change in the preload in the contact angle direction when the temperature of the hub unit bearing 1 rises is great.

FIG. 6 is a diagram showing the relationship between the use environment temperature of the hub unit bearing 1 and the amount of change in the preload in the contact angle direction accompanying the change in the use environment temperature. In FIG. 6, the horizontal axis indicates the operating environment temperature of the hub unit bearing 1 (in the drawing, “temperature [° C.]”), and the vertical axis indicates the contact angle accompanying the change in the operating environment temperature. The amount of change in the preload in the direction (denoted as “preload change amount” in the figure) is shown.
In FIG. 6, as in FIG. 2, the temperature at which the tightening margin is “0” is described as “the point at which the tightening margin is zero”.

(Effect of the second embodiment)
Hereinafter, effects of the present embodiment will be described.
(1) In the hub unit bearing 1 of the present embodiment, the expansion adjustment interval is formed between the raceway member 6b and the outer member-side convex portion 34 with a material having a larger linear expansion coefficient than the outer annular member 4. A seat member 32 is disposed. In other words, the expansion adjustment spacer member 32 is inserted between the raceway member 6b and the outer member side convex portion 34 in a state of being in contact with the raceway member 6b and the outer member side convex portion 34.

For this reason, when the temperature of the hub unit bearing 1 rises, the expansion amount of the expansion adjustment spacer member 32 becomes larger than the expansion amount of the outer annular member 4 including the outer member side convex portion 34. As a result, the degree of pressing of the outer member-side convex portion 34 and the track member 6b by the expansion adjustment spacer member 32 is increased, and the hub unit bearing 1 generates in the direction along the width direction of the rolling element track. Preload increases.
As a result, it is possible to further suppress a change in preload when the temperature rises, as compared with the first embodiment described above.

(Modification)
Hereinafter, modifications of the present embodiment will be listed.
(1) In the hub unit bearing 1 of the present embodiment, the material of the outer annular member 4 and the material of the race members 6a and 6b are the same as those of the outer annular member 4 and the race member 6a even under the second temperature environment. However, the present invention is not limited to this. That is, the material of the outer annular member 4 and the material of the raceway members 6a and 6b are outside in an environment of a preset second temperature that is higher than the first temperature, as in the first embodiment described above. It is good also as a material which a clearance gap generate | occur | produces between the annular member 4 and the track members 6a and 6b.

(2) In the hub unit bearing 1 of the present embodiment, the expansion adjustment spacer member 32 is disposed between the raceway member 6b and the outer member-side convex portion 34. However, the present invention is not limited to this. The spacer member 32 may be disposed between the track member 6a and the outer member side convex portion 34. The hub unit bearing 1 is configured to include two expansion adjustment spacer members 32, and the two expansion adjustment spacer members 32 are respectively disposed between the raceway member 6b and the outer member side convex portion 34. And the raceway member 6a and the outer member side convex portion 34 may be disposed.

DESCRIPTION OF SYMBOLS 1 Hub unit bearing 2 Inner ring member 4 Outer ring member 6a, 6b Track member 8 Rolling body 10 Hub 12 Inner flange 14 Inner raceway surface forming member 16a, 16b Inner raceway raceway surface 18 Fastening member 20 Inward Fastening member insertion hole 22 Outer flange 24 Outer fastening member insertion hole 26 Outer member side convex portion 28a, 28b Outer rolling element raceway surface 30 Rolling body retainer 32 Expansion adjustment spacer member 34 Outer member side convex portion

Claims (1)

An inner annular member having a plurality of rows of inner rolling element raceway surfaces on the outer diameter surface;
An outer annular member having an inner diameter surface facing the outer diameter surface of the inner annular member;
An outer surface that is disposed between the inner annular member and the outer annular member in a state having a tightening margin between the inner annular surface of the outer annular member and that faces the raceways of the plurality of inner rolling elements. Two annular race members each having a rolling element raceway surface;
A plurality of rolling element raceways formed between the outer rolling element raceway surface and the inner rolling element raceway surface are movably loaded, and the outer rolling element raceway surface and the inward direction A plurality of rolling elements in contact with the rolling element raceway surface at an angular contact;
The two track portions Zaido officer, close in the direction in which the rolling element and the portion in contact with the rolling element raceways direction along the width direction of the width direction of the rolling element raceways,
It said outer annular member has a Rusotokata member side protrusion issuing collision toward the radially outer surface of the inner annular member between each track member fit Ri next,
Between each track member and the outer member side convex portion, an expansion adjustment spacer member formed of a material having a larger linear expansion coefficient than the outer annular member is disposed,
Material of the outer annular member, the linear expansion coefficient than the material of the raceway member is rather large, further, interference between the raceway member and the outer annular member in an environment of a first preset temperature Is generated and the inner ring surface of the outer annular member presses the outer surface of the raceway member, and the outer annular member and the above-mentioned in an environment of a preset second temperature that is higher than the first temperature. It is a material that creates a gap with the raceway member,
The material of the raceway member has a tightening margin between the outer annular member and the raceway member in the environment of the first temperature, and the inner diameter surface of the outer annular member presses the outer diameter surface of the raceway member. And a material in which a gap is generated between the outer annular member and the raceway member under the environment of the second temperature,
In an environment below the second temperature, the amount of preload in the contact angle direction of the rolling element raceway decreases as the temperature increases, and in an environment exceeding the second temperature, the rolling element raceway increases as the temperature increases. hub unit bearings preload of the contact angle direction is characterized that you increase.

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