JP7202171B2 - bearing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bearing device used in a transmission or the like, and more specifically, a rolling bearing supports a rotating shaft rotatably with respect to a housing, and a plate screwed to the housing controls axial movement of the outer ring of the rolling bearing. About what to block.

For example, in a transmission such as a dual clutch transmission (DCT) or a continuously variable transmission (CVT) of an automobile, a rotating shaft is rotatably supported by a rolling bearing with respect to a housing of the transmission. A radial load is applied to the rolling bearing from the rotating shaft, and the load applied to the rolling bearing is received by the housing.

The inner ring of the rolling bearing is fitted to the end of the rotating shaft of the transmission, the outer ring of the rolling bearing is fitted to a recess provided in the inner surface of the housing, and the plate is fixed to the recess by a plurality of male screw parts. . The plate is for preventing the outer ring of the rolling bearing from slipping out of the recess (for example, Patent Document 1).

The plate of Patent Document 1 is fastened to the recess of the housing by three externally threaded parts. The plate is axially pressed toward the outer ring by the axial force of the three male threaded parts, and the outer ring is axially restrained by the recess and the plate.

In recent years, in CVT bearings and the like, attention has been focused on the problem of hydrogen embrittlement flaking, which is one of the peculiar flakings. It is not yet clear what kind of mechanism causes hydrogen to enter rolling bearings made of special steel used in CVTs, etc., and to promote embrittlement.

As a countermeasure against the hydrogen embrittlement flaking, it is effective to increase the Cr content of the steel material, which is the bearing material, to form a passivation film on the surface, or to reduce the hydrogen diffusion coefficient by nitriding. (Patent Documents 2 and 3).

JP 2012-132495 A JP 2014-047403 A Japanese Patent Application Laid-Open No. 2003-225270

However, even when special steel is used or special heat treatment for nitriding is performed as in Patent Documents 2 and 3, there is a problem that the rolling bearing becomes expensive.

In addition, in a bearing fixing structure in which a plurality of male-threaded parts fasten a plate to a recess of a housing and an outer ring, an event occurs in which the outer ring is deformed under the influence of the axial force of these male-threaded parts. This deformation of the outer ring causes hydrogen to be trapped in the lattice defects of the outer ring. As the outer ring deforms, the raceway surface of the outer ring ceases to be circular. A passage area occurs where the pressure) is locally high. In this passage area, wear occurs due to metal contact between the outer ring and the rolling elements, and the new surface is likely to be exposed. is considered to be a cause of hydrogen embrittlement flaking that occurs on the raceway surface of the outer ring.

The technique of intentionally lowering the rigidity near each through-hole of the plate as in Patent Document 1 to make the pressing force against the outer ring uniform in the circumferential direction can be expected to be effective if the thickness of the plate is increased. A plate having such a thickness is difficult to form by press working and is formed by cutting, resulting in high cost and heavy weight.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent hydrogen embrittlement flaking in an outer ring of a bearing device while avoiding an increase in cost.

In order to achieve the above object, the present invention includes a rotating shaft, a housing, and a rolling bearing that rotatably supports the rotating shaft with respect to the housing, wherein the rolling bearing is fitted to the rotating shaft. a body having a mated inner ring, an outer ring fitted to the housing, and a plurality of rolling elements arranged between the inner ring and the outer ring, wherein the housing radially supports the outer ring and a plate fixed to the body, and a plurality of externally threaded components axially tightening the plate to the body and the outer ring, wherein the plate and the plurality of externally threaded components are removed from the body The maximum outer ring contact surface pressure in the load bearing region of the rolling bearing is Pmax ₀ when the rotating shaft is operated in the state, and the plate is fixed to the body by the plurality of male threaded parts. When the maximum outer ring contact surface pressure in the load bearing region of the rolling bearing when the rotating shaft is operated is Pmax ₁ , the plurality of male threaded parts have Pmax ₀ so that Pmax ₁ ≤ Pmax ₀ . A configuration was adopted in which it is arranged at a position away from the position of the contact area.

In the load bearing region of the rolling bearing that receives the radial load from the rotating shaft, the surface pressure of the outer ring surface portion (outer ring contact surface pressure) in the contact region between the rolling elements that share the load and the outer ring becomes high. Considering the case where the outer ring is not deformed due to the fixing of the plate, the position of the contact area where the maximum outer ring contact surface pressure Pmax is ₀ in the load bearing area of the rolling bearing is the radial load applied from the rotating shaft to the rolling bearing. determined by the direction of On the other hand, when considering the case where the plate is fixed to the body of the housing by a plurality of male threaded parts, deformation of the outer ring due to the pressing force from the plate tends to increase at positions closer to the male threaded parts. When the thread axis of the male threaded part is positioned on the extension of the radial imaginary straight line connecting the position of the contact area of Pmax ₀ and the rotation center line of the rotating shaft (the line of action of the radial load described above), the load bearing area of the rolling bearing _The position of the contact area with the maximum outer ring contact surface pressure Pmax ₁ is the same as the contact area with _{Pmax 0 .} also higher. The position of the contact area of Pmax ₁ tends to be farther from the line of action of the radial load and Pmax ₁ tends to be lower as the screw axis of the male threaded part is placed farther from the extension of the line of action of the radial load. . Therefore, Pmax ₁ can be made equal to or less than Pmax ₀ by arranging a plurality of externally threaded components appropriately apart from the line of action of the aforementioned radial load. As a result, even if the plate is tightened to the body of the housing and the outer ring by the plurality of male threaded parts and the outer ring is deformed, the contact surface pressure of the outer ring does not increase and wear is prevented in the contact area between the outer ring and the rolling elements. Therefore, generation of a new surface on the outer ring is prevented, and generation of hydrogen due to contact between the new surface and the lubricant is suppressed, thereby preventing hydrogen embrittlement flaking of the outer ring. In this way, since hydrogen embrittlement flaking of the outer ring is prevented by arranging a plurality of male threaded parts, it is necessary to set the thickness of the plate thicker or adopt special steel or special heat treatment for the outer ring as described in Patent Documents 2 and 3. This eliminates the need for additional work, thus avoiding cost increases.

Specifically, when the virtual straight line in the radial direction passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, the phases of the plurality of male screw components considered in one direction from the phase of 0° and the phase of 0° Therefore, it is preferable that the phases of the plurality of externally threaded components considered in one direction and in the opposite direction are the same. By doing so, the axial forces of the plurality of externally threaded parts can be applied to the plate in a well-balanced manner on the basis of the phase of 0°.

More preferably, the total number of the plurality of male screw components is three. When the total number of male threaded parts is 4 or more, the phase difference between adjacent male threaded parts becomes 90° or less, and each male threaded part can be separated from the position of the contact area of Pmax ₀ until Pmax ₁ ≤ Pmax ₀ . it gets harder. If the total number of male threaded parts is two, the plate will warp due to the axial force of these male threaded parts.

Further, when the virtual straight line in the radial direction passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, the screw axes of the plurality of male threaded parts are separated from the phase of 0° in one direction by +40° or more and It is preferable that they are arranged in a range separated by -40° or more in one direction and in the opposite direction. In this way, Pmax ₁ can be made equal to or less than Pmax ₀ for the bearing type and bearing major dimensions that are common in bearing devices for transmissions.

The plate is preferably formed of a single metal plate having a thickness of 5 mm or less. In this way, the plate does not become heavy, and it is unnecessary to form the plate by cutting, so that the bearing device can be made suitable for transmission applications.

For example, the rotating shaft is a rotating shaft provided in a transmission. By doing so, it is possible to improve the durability of the bearing device provided in the transmission while avoiding an increase in cost.

As described above, the present invention can prevent hydrogen embrittlement flaking of the outer ring of the bearing device while avoiding an increase in cost by adopting the above-described configuration, and can realize a bearing device suitable for transmission applications. can.

FIG. 2 is a cross-sectional view taken along line II of FIG. 2 showing a bearing device according to an embodiment of the present invention; II-II line sectional view of FIG. Graph showing the results of numerical analysis exploring the effect of deformation of the outer ring of a rolling bearing on the distribution of outer ring contact surface pressure Line graph based on the results of numerical analysis in Fig. 3

An embodiment as an example of a bearing device according to the present invention will be described with reference to the accompanying drawings. 1 and 2 show an example of application to a belt-type CVT (hereinafter simply referred to as "CVT") as an example of applying the bearing device according to the embodiment to an automobile transmission. 1 is a sectional view taken along line II of FIG.

As shown in FIG. 2, the CVT has a known structure comprising a primary pulley 1, a secondary pulley (not shown), and a power transmission belt 2 stretched between the primary pulley 1 and the secondary pulley. .

The bearing device according to the embodiment includes a rotating shaft 3 , a housing 4 , and a rolling bearing 5 that supports the rotating shaft 3 rotatably with respect to the housing 4 .

The primary pulley 1 has a fixed sheave 6 and a movable sheave 7 that can approach and move away from the fixed sheave 6 . A fixed sheave 6 is fixed to the rotating shaft 3 . The movable sheave 7 is supported by the rotating shaft 3 so as to be slidable in the axial direction and not relatively rotatable. The position of the movable sheave 7 is controlled by hydraulic pressure to adjust the gear ratio between the primary pulley 1 and the secondary pulley. 2, illustration of a mechanism for displacing the movable sheave 7 in the axial direction is omitted.

Like the primary pulley 1, the aforementioned secondary pulley also has a fixed sheave and a movable sheave. One of the primary pulley 1 and the secondary pulley (the primary pulley 1 in the illustrated example) is disposed obliquely above the other pulley, and one end of the rotary shaft 3 integrated with the fixed sheave 6 of the one pulley is a rolling bearing. 5.

The rotating shaft 3 rotates integrally with a fixed sheave 6 and a movable sheave 7 that are rotationally driven by the power transmission belt 2 and serves as the center of rotation of these sheaves 6 and 7 . The rotating shaft 3 has a hollow rotating shaft shape, and it is possible to supply lubricating oil to the rolling bearing 5 through the hollow hole. One end of the rotating shaft 3 is rotatably supported by a rolling bearing 5 with respect to the housing 4 . The other end side of the rotating shaft 3 is also rotatably supported with respect to the housing 4 by another rolling bearing, but illustration of the support structure for the other end side of the rotating shaft 3 is omitted in FIG.

Hereinafter, the direction along the rotation centerline of the rotating shaft 3 is referred to as the "axial direction". Also, the direction along the circumference of the rotating shaft 3 around the center line of rotation is referred to as the "circumferential direction". A direction perpendicular to the rotation center line of the rotating shaft 3 is called a "radial direction".

The housing 4 is configured as part of a CVT casing that accommodates the primary pulley 1, the secondary pulley, and the like. The housing 4 is stationary with respect to the rotating shaft 3 and supports the rolling bearing 5 radially and axially.

The rolling bearing 5 is constructed as a radial bearing. As shown in FIGS. 1 and 2, the rolling bearing 5 is arranged between an inner ring 8 fitted to the rotating shaft 3, an outer ring 9 fitted to the housing 4, and the inner ring 8 and the outer ring 9. and a plurality of rolling elements 10 .

The inner ring 8 is an annular bearing component having a raceway surface on the outer peripheral side. The outer ring 9 is an annular bearing component having a raceway surface on the inner peripheral side. The rolling element 10 is a bearing component having rolling surfaces corresponding to the raceway surface of the inner ring 8 and the raceway surface of the outer ring 9 .

The inner ring 8 is fitted on the outer circumference of the rotating shaft 3 so as to rotate together with the rotating shaft 3 . Outer ring 9 is fixed to housing 4 .

The inner ring 8, outer ring 9 and rolling elements 10 are each made of steel.

In the drawing, a deep groove ball bearing is exemplified as the rolling bearing 5 . The raceway surface of the inner ring 8 and the raceway surface of the outer ring 9 each have an arcuate cross-section, and are formed to have the same cross-sectional shape over the entire circumferential direction. The rolling elements 10 consist of balls.

The direction of the maximum radial load applied from the rotating shaft 3 to the rolling bearing 5 is substantially constant. In the CVT of FIG. 2, a CVT in which the primary pulley 1 is diagonally above the secondary pulley is assumed. Therefore, the maximum radial load is applied to the rolling bearing 5 supporting the primary pulley 1 in the obliquely downward direction from the rotating shaft 3 . In FIG. 1, the line of action of the radial load P is indicated by an arrow.

As shown in FIGS. 1 and 2, the housing 4 includes a body 11 that radially supports the outer ring 9, a plate 12 that is fixed to the body 11, and a plurality of plates that fasten the plate 12 to the body 11 and the outer ring 9 in the axial direction. and a male threaded component 13 of .

The body 11 includes a cylindrical bearing seat surface 11a fitted to the outer diameter surface of the outer ring 9, and an end face on one axial side (left side in FIG. 2) of the outer ring 9 fitted to the bearing seat surface 11a. a shoulder portion 11b that supports the bearing surface 11a, a fastening surface 11c that continues to the other axial side (the right side in FIG. 2) of the bearing seat surface 11a, and a plurality of screw through portions that are positioned radially outward from the bearing seat surface 11a. 11d.

The thickness between the bearing surface 11a and the outer surface of the body 11 is set so as to ensure the strength to keep the roundness of the outer diameter surface of the outer ring 9 within a predetermined range. Therefore, the radial load applied from the rotating shaft 3 to the rolling bearing 5 does not excessively deform the outer ring 9 into an elliptical shape.

The fastening surface 11c is formed as a flat surface that continues along the entire circumference in the circumferential direction and extends in the radial direction. The fastening surface 11c is a portion that contacts the plate 12 in the axial direction.

The screw through portion 11d defines a through hole into which the screw rotating shaft of the male screw component 13 can be axially inserted. The total number of the plurality of threaded through portions 11d formed in the body 11 is three. These screw through portions 11d are arranged at equal intervals in the circumferential direction (that is, at intervals of ₁₂₀ ° around the rotation center line O1 of the rotating shaft 3).

The plate 12 has an opening 12 a arranged around the rotation axis 3 and a plurality of female threads 12 b corresponding to the screw rotation axes of the male threaded component 13 . The opening 12a contacts the outer circumferential stepped portion 9a of the outer ring 9 fitted to the bearing seat surface 11a in the axial and radial directions.

The outer periphery of the plate 12 is formed in a hexagonal shape in which corners of an equilateral triangle are equally omitted. The total number of female threaded portions 12b is 3, which is the same as the total number of threaded through portions 11d. These female screw portions 12b are arranged at equal intervals in the circumferential direction. The female threaded portion 12b is arranged between three short sides of the six sides forming the hexagonal shape on the outer periphery of the plate 12 and the opening 12a.

The plate 12 is formed of a single metal plate with a thickness of 5 mm or less. The overall shape of plate 12 is press formed. The press-formed product is threaded to form the internal thread portion 12b.

The total number of the plurality of externally threaded components 13 is the same number as the threaded through portions 11d and the internally threaded portions 12b. Although the male screw component 13 is illustrated as a hexagon bolt, it is not limited to this.

The plate 12 is fixed to the body 11 by screwing the plurality of male threaded parts 13 from the threaded through portion 11d of the body 11 into the plurality of female threaded portions 12b of the plate 12, thereby preventing the axial movement of the outer ring 9 with respect to the housing 4. Become. At this time, the screw axes _O2 of the three male screw parts 13 are arranged at intervals of 120° in the circumferential direction. The plate 12 is axially fastened to the fastening surface 11c of the body 11 and the outer peripheral stepped portion 9a of the outer ring 9 on one axial side thereof by the axial force of these male threaded parts 13 . By this tightening, an axial pressing force is applied from the plate 12 to the outer ring 9, and the shoulder portion 11b of the body 11 is pushed from the outer ring 9 toward one side in the axial direction.

The axial force of each externally threaded component 13 is set to several tons so that the plate 12 resists the axial displacement behavior of the rolling bearing 5 when a reverse input is applied to the rotating shaft 3 of the CVT. Since there is no backup surface for axially supporting the vicinity of the shoulder portion 11 b of the body 11 from the outside of the housing 4 , the pressing force applied from the plate 12 to the outer ring 9 is large enough to deform the outer ring 9 together with the housing 4 . . The pressing force tends to increase as it gets closer to the male threaded component 13 and to decrease as it moves away from the male threaded component 13 . Therefore, the deformation of the outer ring 9 also has the same tendency. Therefore, the raceway surface of the outer ring 9 is greatly distorted in the axial direction at a position closer to the male threaded component 13, and the rolling elements 10 are less likely to roll smoothly. This acts in the direction of increasing the outer ring contact surface pressure in the load bearing region of the rolling bearing 5 . Here, the load bearing region of the rolling bearing 5 refers to a region of the rolling bearing 5 that is part of the circumferential direction and receives a radial load. Further, the outer ring contact surface pressure is the surface pressure in the contact area with one rolling element 10 on the raceway surface of the outer ring 9 . The outer ring contact surface pressure can be obtained by numerical analysis as a value of Pmax in Hertz's elastic contact theory.

The inventor of the present application conducted numerical analysis to explore the relationship between the position of the male threaded component and Pmax. In the numerical analysis, a deep groove ball bearing of product number 6010 of the present applicant was adopted as an analysis object as a rolling bearing having a common bearing type and major dimensions for CVT applications. Also, in the numerical analysis, a load applied from the rotating shaft to the rolling bearing was assumed, and an equivalent radial load of known magnitude for CVT applications was applied to the analysis target. The direction of the equivalent radial load was set in one direction from the rotation center line of the rotating shaft.

In the numerical analysis, model 1 was assumed to apply the above-mentioned equivalent radial load without setting the deformation of the outer ring, assuming that the aforementioned pressing force was not applied to the outer ring. Further, in the numerical analysis, models 2 to 4 were assumed to deform the outer ring due to the aforementioned pressing force, set the deformation of the outer ring to be analyzed, and apply the aforementioned equivalent radial load.

In Model 2, the amount of deformation of the outer ring raceway surface on the line of action of the equivalent radial load was set to 15 μm, and the phase on the line of action was set to 0°. The amount of deformation of the outer ring raceway surface of model 2 was set smaller as the phase was farther from the phase 0°. The first rolling element is the rolling element that contacts the outer ring at the position of the phase 0°, and the second rolling element is the rolling element that is located first in one direction in the circumferential direction from the first rolling element, Assuming that the third rolling element is the second rolling element in one direction of the circumference from the first rolling element, in Models 3 and 4, the outer ring raceway surface Changed the amount of deformation of . That is, in model 3, the amount of deformation of the outer ring raceway surface in the first phase, which is the contact area between the second rolling element and the outer ring, was set to 15 μm. The amount of deformation of the outer ring raceway surface of model 3 was set to be smaller as the phase was further away from the first phase. In model 4, the amount of deformation of the outer ring raceway surface in the second phase, which is the contact area between the third rolling element and the outer ring, was set to 15 μm. The amount of deformation of the outer ring raceway surface of model 4 was set to be smaller as the phase was farther from the second phase. These models 2 to 4 are based on the assumption that the thread axis of the male threaded component is arranged on a radial imaginary straight line passing through the contact area between the corresponding rolling elements and the outer ring.

The distribution of the outer ring contact surface pressure (surface pressure distribution) was analyzed in Models 1 to 4 described above. The outer ring contact surface pressure at various phases was obtained for each model, and it was investigated how the outer ring contact surface pressure changes according to the phase. The analysis results are shown graphically in FIG. In FIG. 3, the vertical axis of the graph indicates the ratio to the maximum outer ring contact surface pressure in the surface pressure distribution of model 1, and the horizontal axis of the graph indicates the phase, which is the relative angle to the aforementioned phase of 0°. A positive relative angle indicates the one-way phase in the circumferential direction from the 0° phase position, and a negative relative angle indicates the one-way and opposite phases from the 0° phase position.

From the graph of model 1, it can be seen that when the outer ring is not deformed, the outer ring contact surface pressure is maximized in the contact area with a phase of 0°, which is on the line of action of the equivalent radial load, and decreases parabolically according to the phase.

From the graph of Model 2, when the thread axis of the male threaded part is placed on the extension of the line of action of the equivalent radial load (phase 0°), the maximum outer ring contact surface pressure in the surface pressure distribution occurs in the contact area with phase 0°. , the maximum outer ring contact surface pressure in model 1 is higher by 10% or more.

From the graphs of Models 3 and 4, when the thread axis of the male threaded part is arranged at a phase away from phase 0°, the maximum outer ring contact surface pressure in the surface pressure distribution occurs in the contact area with a phase away from phase 0°. I know it will be lower.

Furthermore, from the graph of model 4, when the thread axis of the male threaded part is placed in a phase sufficiently distant from the phase 0°, the maximum outer ring contact surface pressure in the surface pressure distribution is the maximum outer ring in model 1 with no deformation of the outer ring. It turns out that it becomes lower than a contact surface pressure.

FIG. 4 is a line graph showing the relationship between the maximum outer ring contact surface pressure and the phase in each surface pressure distribution of Models 1 to 4 in FIG. In this line graph, the vertical axis indicates the ratio to the maximum outer ring contact surface pressure in the surface pressure distribution of Model 1, and the horizontal axis indicates the phase, which is the relative angle to the aforementioned phase of 0°.

The vertical axis value at the position where the line graph in FIG. 4 intersects the scale line of phase 40° is about 101%. Considering the error of the numerical analysis, when the deformation of the outer ring raceway surface becomes maximum at the position of phase 40°, the maximum outer ring contact surface pressure in the surface pressure distribution of Model 1 is the maximum outer ring contact surface pressure in the surface pressure distribution There is practically no problem even if it is considered to be equivalent to the surface pressure.

As shown in Figs. 3 and 4, in this numerical analysis, it was assumed that the position of the thread axis of the male threaded part was changed from 0° in one direction, but the figure also shows the case of changing the direction in one direction and in the opposite direction. The surface pressure distributions of Models 3 and 4 of 3 appear bilaterally symmetrically with the scale line of phase 0° as the axis of symmetry.

From the results of the above-mentioned numerical analysis, the maximum outer ring contact surface pressure in the surface pressure distribution when the position of the screw axis of the male threaded component is arranged in a phase separated from the phase 0° by ±40° or more is the surface pressure distribution of Model 1. It is considered to be equal to or less than the maximum outer ring contact surface pressure at

Therefore, in the bearing device shown in FIGS. 1 and 2, the plurality of male threaded parts 13 are arranged to suppress the maximum outer ring contact surface pressure within the load bearing region of the rolling bearing 5 . That is, when the rotating shaft 3 is operated with the plate 12 and the plurality of male threaded parts 13 removed from the body 11, the maximum outer ring contact surface pressure in the load bearing range of the rolling bearing 5 is Pmax ₀ , and the plate 12 is fixed to the body 11 by a plurality of male threaded parts 13, and the maximum outer ring contact surface pressure in the load bearing region of the rolling bearing 5 is Pmax ₁ when the rotating shaft 3 is operated. The externally threaded component 13 is arranged at a position away from the contact area position of Pmax ₀ such that Pmax ₁ ≦Pmax ₀ .

Specifically, the contact area of Pmax ₀ occurs on the line of action of the radial load P, as shown in FIG. When a radial imaginary straight line passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, each screw axis O ₂ of the plurality of male threaded parts 13 rotates in one direction (clockwise in FIG. 1) from the phase of 0°. They are arranged in a range separated by +40° or more and separated by −40° or more in the direction opposite to the one direction (counterclockwise in FIG. 1).

The position of the screw axis _O2 of one of the three male threaded parts 13 arranged at equal intervals in the circumferential direction is arranged at a phase of ±180° with the position of the contact area of Pmax ₀ . ing. Therefore, the phases of the plurality of male threaded components 13 considered in one direction from the phase 0° are equivalent to the phases of the plurality of male threaded components considered in one direction and the opposite direction from the phase 0°.

The bearing device according to the embodiment is as described above, and the plurality of male threaded components 13 are arranged at positions distant from the contact area position of Pmax ₀ such that Pmax ₁ ≤ Pmax ₀ . Even if the plate 12 is tightened to the body 11 of the housing 4 and the outer ring 9 by the plurality of male threaded parts 13 and the outer ring 9 is deformed, the contact surface pressure of the outer ring does not increase and the contact area between the outer ring 9 and the rolling elements 10 is not worn. prevented.

Whether or not hydrogen embrittlement flaking occurs on the raceway surface of the outer ring 9 is considered to be affected by whether or not the raceway surface of the outer ring 9 and the rolling elements 10 come into contact with each other and wear occurs on the raceway surface. Whether the raceway surface of the outer ring 9 wears or not depends on the linear functional relationship between the minimum oil film thickness between the raceway surface of the outer ring 9 and the rolling elements 10 and the outer ring contact surface pressure. That is, as the outer ring contact surface pressure increases, the threshold value of the minimum oil film thickness necessary for preventing wear (that is, preventing hydrogen embrittlement flaking) increases. If the minimum oil film thickness satisfies the aforementioned threshold values at Pmax ₁ and Pmax ₀ , it is considered that hydrogen embrittlement flaking does not occur on the raceway surface of the outer ring 9 . Even if the fixing of the plate 12 causes deformation of the outer ring 9, if Pmax ₁ is equal to or less than Pmax ₀ , the above threshold value will not increase. Therefore, formation of a new surface due to wear of the raceway surface of the outer ring 9 is prevented, and generation of hydrogen due to contact between the new surface and the lubricant is suppressed, so hydrogen embrittlement flaking of the outer ring 9 is prevented.

In addition, since the arrangement of the plurality of male threaded parts 13 prevents the outer ring 9 from being delaminated due to hydrogen embrittlement, the thickness of the plate 12 is set thicker, the material of the outer ring 9 is made of special steel, or the outer ring 9 is subjected to a special heat treatment. This eliminates the need for additional work, thus avoiding cost increases.

As described above, the bearing device according to the embodiment can prevent hydrogen embrittlement flaking of the outer ring 9 while avoiding an increase in cost.

Further, in the bearing device according to the embodiment, when the virtual straight line in the radial direction passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, the phases of the plurality of male threaded components 13 considered in one direction from the phase of 0° Since the phases of the plurality of male threaded parts 13 considered in one direction and the opposite direction from the phase 0° are equivalent, the axial force of the plurality of male threaded parts 13 can be applied to the plate 12 in a well-balanced manner with the phase 0° as a reference. can.

Further, in the bearing device according to the embodiment, since the total number of the plurality of male threaded components 13 is three, each male threaded component 13 can be separated from the position of the contact area of Pmax ₀ until Pmax ₁ ≦Pmax ₀ . Also, warping of the plate 12 due to the axial force of each male screw component 13 can be suppressed.

In addition, in the bearing device according to the embodiment, when the phase of the imaginary straight line in the radial direction passing through the position of the contact area of Pmax ₀ is set to 0°, the screw axes _O2 of the plurality of male threaded components 13 shift from the phase of 0° to one side. Since it is arranged in a range of +40° or more in one direction and -40° or more in the opposite direction, Pmax ₁ is equivalent to Pmax ₀ in the general bearing type and bearing major dimensions in bearing devices for transmissions. You can:

Further, in the bearing device according to the embodiment, since the plate 12 is formed of a single metal plate having a thickness of 5 mm or less, the plate 12 does not become heavy, and the plate 12 does not need to be formed by cutting. Therefore, the bearing device can be made suitable for transmission applications.

Further, in the bearing device according to the embodiment, since the rotating shaft 3 is the rotating shaft provided in the transmission, it is possible to improve the durability of the bearing device provided in the transmission while avoiding an increase in cost.

The positions of the contact areas of Pmax ₀ and Pmax ₁ can also be searched experimentally. That is, the raceway surface of the outer ring 9 has a slight depth of contact trace (permanent deformation in which the contact area with the rolling element 10 is slightly recessed). Since the depth of the contact marks corresponds to the height of the contact surface pressure of the outer ring, the positions of the contact areas of Pmax ₀ and Pmax ₁ can be determined from the changes in the depth of the contact marks, excluding abnormal marks due to the entrapment of foreign matter. can know.

In the illustrated example, the bearing device according to the embodiment is applied to support the rotation shaft 3 of the primary pulley 1. However, for a CVT in which the positional relationship between the primary pulley and the secondary pulley is opposite to that described above, the secondary pulley A load is applied obliquely downward to the rolling bearing that supports the . Therefore, it is possible to apply the bearing device according to the embodiment also in this case.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims.

3 Rotating shaft 4 Housing 5 Rolling bearing 8 Inner ring 9 Outer ring 10 Rolling element 11 Body 12 Plate 13 Male screw part

Claims (4)

a rotating shaft, a housing, and a rolling bearing that rotatably supports the rotating shaft with respect to the housing;
The rolling bearing has an inner ring fitted to the rotating shaft, an outer ring fitted to the housing, and a plurality of rolling elements arranged between the inner ring and the outer ring,
A bearing device in which the housing includes a body that radially supports the outer ring, a plate fixed to the body, and a plurality of externally threaded parts that axially fasten the plate to the body and the outer ring,
When the rotating shaft is operated with the plate and the plurality of externally threaded parts removed from the body, the maximum outer ring contact surface pressure in the load bearing range of the rolling bearing is Pmax ₀ , and the plate is When the rotating shaft is driven while being fixed to the body by the plurality of male threaded parts, the maximum outer ring contact surface pressure in the load bearing range of the rolling bearing is Pmax ₁ , the plurality of male screws the component is positioned away from the contact area location of Pmax ₀ such that Pmax ₁ ≤ Pmax ₀ ;
The rotating shaft comprises a rotating shaft provided in a transmission of an automobile,
wherein the transmission comprises a continuously variable transmission including a primary pulley, a secondary pulley, and a power transmission belt stretched between the primary pulley and the secondary pulley;
The contact area of Pmax ₀ occurs on the line of action of the radial load applied from the rotating shaft to the rolling bearing that supports the primary pulley or the secondary pulley, and the direction of the line of action of the radial load is vertical. obliquely downward with respect to the direction of
When the virtual straight line in the radial direction passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, the screw axes of the plurality of male threaded parts are separated from the phase of 0° in one direction by +40° or more in the one direction and A bearing device characterized in that it is arranged in a range separated by -40° or more in the direction opposite to the . When the virtual straight line in the radial direction passing through the position of the contact area of Pmax ₀ is assumed to have a phase of 0°, the phases of the plurality of male screw components considered in one direction from phase 0°, and the one direction from phase 0° 2. A bearing device according to claim 1, wherein the phases of said plurality of externally threaded parts when considered in opposite directions are equivalent. 3. The bearing device according to claim 2, wherein the total number of said plurality of externally threaded components is three. 4. The bearing device according to any one of claims 1 to 3 , wherein the plate is formed of a single metal plate having a thickness of 5 mm or less.

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