JP6741518B2 - Rolling device for vehicle - Google Patents

Description

The present invention relates to a rolling device for vehicles.

Patent Document 1 discloses a tapered roller bearing including an inner ring, an outer member, a tapered roller, and a cage. The inner ring has a conical raceway surface on the outer circumference, and the outer member has a conical raceway surface on the inner circumference. A plurality of tapered rollers are rollably interposed between the raceway surface of the inner ring and the raceway surface of the outer member. The tapered roller is housed in a pocket formed in the cage. The movement of each tapered roller in the axial direction is restricted by a small flange and a large flange provided on both sides of the raceway surface of the inner ring.

The cage includes a small annular portion continuous on the small end surface side of the tapered roller, a large annular portion continuous on the large end surface side of the tapered roller, and a plurality of column portions connecting the small annular portion and the large annular portion, A pocket is formed between the adjacent pillars. The cage pocket has a trapezoidal shape, and the portion that accommodates the small diameter side of the tapered roller is the narrow side and the portion that accommodates the large diameter side is the wide side. On the narrow side and the wide side of the pocket, two notches are provided in each of the column portions on both sides, the notch being cut from the outer diameter side to the inner diameter side.

JP, 2008-51272, A JP, 11-44319, A JP, 2009-248595, A JP, 2006-342877, A JP 2006-214506 A

In Patent Document 1, by devising the shape of the cage, the torque is reduced without lowering the rigidity of the bearing. However, the invention of Patent Document 1 has the following problems, for example.
・Cages are formed in the cage, which reduces the strength of the cage.
・ If the protrusion of the cage repeatedly collides with the raceway surface of the outer member while the bearing is in use, the protrusion will wear, and an oil film cannot be formed between the raceway surface and the protrusion, resulting in a torque increase. Increase.

Then, the objective of this invention is providing the rolling device for vehicles which can improve rigidity, suppressing the increase of a rotation torque.

The rolling device for a vehicle of the present invention for solving the above-mentioned problems includes an outer ring portion and an inner ring portion, rolling elements provided between the outer ring portion and the inner ring portion, the outer ring portion and the inner ring portion. And a grease arranged on the rolling surface of the rolling element in, the gap of the rolling element with respect to the rolling surface is set to a negative gap, and the grease contains poly-α-olefin and has a movement at 40°C. A base oil having a viscosity of 20 to 60 mm ² /s, a thickening agent containing a urea compound obtained by reacting a mixed amine of an alicyclic amine and an aromatic amine, and a diisocyanate compound, and a phosphite ester, The base oil, which contains an ether compound and an additive containing oxidized paraffin, has a traction coefficient of 0.02 or less and a pour point of -50°C or less (claim 1).
The rolling device for a vehicle of the present invention includes an outer ring portion and an inner ring portion, rolling elements provided between the outer ring portion and the inner ring portion, and rolling elements of the rolling element in the outer ring portion and the inner ring portion. And a grease arranged on the moving surface, the gap of the rolling element with respect to the rolling surface is set to a negative gap, and the grease contains poly-α-olefin and has a kinematic viscosity at 40° C. of 20 to 60 mm ² / a base oil which is s, a thickening agent containing a urea compound obtained by reacting a mixed amine of an alicyclic amine and an aromatic amine, and a diisocyanate compound, a phosphite ester, an ether compound and paraffin oxide And an additive containing, the ether compound has a polar group consisting of a 5-membered ring having at least one hetero atom at the end of the molecule (claim 2).

In the rolling device for a vehicle of the present invention, the base oil preferably has a traction coefficient of 0.02 or less and a pour point of -50°C or less (claim 3).
In the rolling device for a vehicle of the present invention, it is preferable that the range of the negative gap is −0.06 mm to −0.1 mm (claim 4 ).

In the rolling device for a vehicle of the present invention, the grease contains 10 to 25% by mass of the thickener, 0.2 to 5% by mass of the phosphite, and 0.2 to 5% by mass of the ether compound. % And 0.5 to 10 mass% of oxidized paraffin are preferably contained (Claim 5).

According to the rolling device for a vehicle of the present invention, since the grease contains poly-α-olefin having a kinematic viscosity of 20 to 60 mm ² /s (40° C.) as a base oil, it is possible to reduce the rotational torque of the rolling element. .. Therefore, even if the absolute value of the negative value of the internal clearance between the rolling element and the rolling surfaces of the outer ring portion and the inner ring portion is increased, the rotational torque can be kept relatively small. Therefore, it is possible to improve the rigidity while suppressing an increase in the rotation torque.

FIG. 1 is a sectional view showing a hub unit according to an embodiment of the present invention. FIG. 2 is a perspective view showing a flange portion of the hub unit. FIG. 3 is a front view showing the flange portion. FIG. 4 is a diagram showing the relationship between the internal clearance and the rotation torque. FIG. 5 is a diagram showing the relationship between the internal clearance and the rigidity value.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing a hub unit 1 according to an embodiment of the present invention. The left-right direction of FIG. 1 is referred to as the axial direction of the hub unit 1, the left side of FIG. 1 is referred to as the outer side in the axial direction, and the right side is referred to as the inner side in the axial direction.
A hub unit 1 as an example of a rolling device for a vehicle of the present invention supports, for example, wheels of an automobile so as to be rotatable with respect to a suspension device on the vehicle body side. The hub unit 1 includes a rolling bearing 2, a hub wheel 3 that serves as a race ring member of the rolling bearing 2, and an annular flange portion 4 provided integrally with the hub wheel 3. The materials of the hub wheel 3 and the flange portion 4 of this embodiment are formed by hot forging, for example.

The hub wheel 3 has a small-diameter portion 7 having a circular cross-section, a caulking portion 8 in which an axially inner end portion of the small-diameter portion 7 is bent and deformed outward in the radial direction, and the small-diameter portion 7 has a diameter larger than that of the small-diameter portion 7. And a large-diameter portion 9 having a circular cross-section that is continuously provided toward the outside in the axial direction. On the large-diameter portion 9 of the hub wheel 3, the flange portion 4 extending outward in the radial direction from the outer peripheral surface thereof is bent and formed.

The rolling bearing 2 is, for example, a double-row ball bearing, and has an outer ring 11 having a pair of outer ring raceway surfaces (rolling surfaces) 11a and 11b on the inner peripheral surface, and an outer peripheral surface of the small diameter portion 7 of the hub wheel 3 on the inner peripheral surface. 7a, and the inner ring member 12 fitted so as to be in close contact with the inner ring 7a. The inner ring member 12 has an inner ring raceway surface (rolling surface) 13a facing the outer ring raceway surface 11a on the inner side in the axial direction on the outer circumferential surface thereof, and the large-diameter portion 9 of the hub wheel 3 has an outer circumferential surface thereof. Has an inner ring raceway surface (rolling surface) 13b facing the outer ring raceway surface 11b on the outer side in the axial direction.

The rolling bearing 2 is composed of a plurality of balls arranged in two rows so as to be rollable between the outer ring raceway surface 11a and the inner ring raceway surface 13a and between the outer ring raceway surface 11b and the inner ring raceway surface 13b. It includes a rolling element 14 and a pair of cages 15 that hold the rolling elements 14 arranged in these two rows at predetermined intervals in the circumferential direction.
The rolling element 14 is assembled with a negative (axial) clearance provided to the outer ring raceway surfaces 11a, 11b and the inner ring raceway surfaces 13a, 13b. The negative clearance with respect to the rolling element 14 is set, for example, by axially tightening (increasing the preload) the inner ring portion, in this embodiment, the large diameter portion 9 of the hub wheel 3 and the inner ring member 12. In this embodiment, the range of the negative clearance of the rolling element 14 is relatively small, and may be, for example, -0.06 mm to -0.1 mm, preferably -0.08 mm to -0.1 mm. The negative gap may be set, for example, by the method disclosed in Patent Documents 2 to 5 above. Further, the gap amount (preload amount) is, for example, paragraphs [0010] to [0020] of Patent Document 2, paragraphs [0010] to [0018] of Patent Document 3, and paragraphs [0018] to [0033] of Patent Document 4. ] And the method disclosed in paragraphs [0022] to [0027] of Patent Document 5.

The rolling bearing 2 also includes seal members 16 that seal the annular space formed between the hub wheel 3 and the outer ring 11 from both axial ends. Grease G is enclosed in the annular space 16a sealed by the seal member 16. The grease G spreads over the outer ring raceways 11a, 11b and the inner ring raceways 13a, 13b in the annular space 16a and imparts lubricity to these raceways 11a, 11b, 13a, 13b.

Further, the rolling bearing 2 has a bearing flange 17 extending radially outward from the outer peripheral surface 11c of the outer ring 11. The bearing flange 17 is formed with a plurality of bolt holes 17a penetrating in the thickness direction. The hub bolt B is inserted into the bolt hole 17a and screwed into the knuckle 51 of the suspension device. Thereby, the bearing flange 17 is fixed to the knuckle 51.

FIG. 2 is a perspective view showing the flange portion 4, and FIG. 3 is a front view showing the flange portion 4.
2 and 3, the flange portion 4 has a plurality of (five in this embodiment) thick portions 21 formed at predetermined intervals in the circumferential direction. Each thick-walled portion 21 is formed so that the end surface on the inner side in the axial direction is raised, and is formed so as to radially extend in the radial direction in the front view of FIG. 3. Further, each thick portion 21 has a predetermined width W in the circumferential direction (hereinafter, referred to as circumferential width W).

One bolt hole 22 penetrating in the thickness direction is formed at the outer side in the radial direction of each of the thick portions 21 at a substantially central portion of the circumferential width W. As shown in FIG. 1, hub bolts B for attaching wheels and brake discs are fixed to the respective bolt holes 22 by press fitting. Therefore, the diameter d (see FIG. 3) of the bolt hole 22 is set to a size that allows the hub bolt B to be press-fitted.

Next, the composition of the grease G sealed in the hub unit 1 will be described.
Grease G contains a base oil, a thickener, and an additive.
As the base oil, a synthetic oil containing a poly-α-olefin and having a kinematic viscosity at 40° C. of 20 to 60 mm ² /s (40° C.) is used. However, the grease G may include other base oil such as mineral oil.
As the poly α-olefin, typically, an oligomer or cooligomer of an α-olefin having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms (1-octene oligomer, decene oligomer, ethylene-propylene cooligomer, etc.) and those Examples include hydrides.

Regarding the physical properties of the base oil, the following ranges are preferable. That is, the kinematic viscosity (according to JIS K 2283) is 20 to 60 mm ² /s (40° C.), preferably 25 to 55 mm ² /s (40° C.). When the kinematic viscosity of the base oil is in the above range, it is possible to reduce the frictional resistance of the sliding portion of the bearing as compared with the grease in which the base oil of about 70 to 100 mm ² /s (40° C.) is used. .. Further, the pour point (according to JIS K 2269) is preferably −50° C. or lower, and more preferably −70° C. to −50° C. If the pour point of the base oil is within the above range, the fluidity of the grease G can be ensured in a low temperature environment (for example, -40°C or lower), so that the base oil can be easily distributed to the sliding portion of the bearing. it can. Therefore, the effect of suppressing low-temperature fretting can be improved. Further, the traction coefficient is, for example, 0.02 or less, preferably 0.001 or more and 0.01 or less. When the traction coefficient of the base oil is within the above range, the torque of the grease G can be reduced. The traction coefficient can be measured, for example, by using a base oil on a Disk on Roller under the conditions of a surface pressure of 0.5 GPa, a peripheral speed of 0.5 m/sec, and a slip ratio of 3%.

Further, the blending amount of the base oil is preferably 60 to 90% by mass, and more preferably 65 to 88% by mass with respect to the total amount of the grease G.
As the thickener, a urea compound obtained by reacting a mixed amine of an alicyclic amine and an aromatic amine with a diisocyanate compound is used. Examples of the urea compound include urea compounds such as diurea compounds, triurea compounds, tetraurea compounds, polyurea compounds (excluding diurea compounds, triurea compounds and tetraurea compounds), urethane compounds such as urea/urethane compounds and diurethanes, or a mixture thereof. Etc. Of these, diurea compounds are preferably used. With this combination of urea compounds, the occurrence of fretting can be reduced.

Examples of the alicyclic amine include cyclohexylamine and dicyclohexylamine, and examples of the aromatic amine include aniline and p-toluidine.
Examples of diisocyanate compounds include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and the like. Examples of the aliphatic diisocyanate include diisocyanates having saturated and/or unsaturated linear or branched hydrocarbon groups, and specifically, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate (HDI) and the like. Is mentioned. Examples of the alicyclic diisocyanate include cyclohexyl diisocyanate and dicyclohexylmethane diisocyanate. Examples of aromatic diisocyanates include phenylene diisocyanate, tolylene diisocyanate (TDI), diphenyl diisocyanate and diphenylmethane diisocyanate (MDI).

When a mixed amine of an alicyclic amine and an aromatic amine is used as a raw material for the urea compound, the mixing ratio (mass ratio) of the alicyclic amine and the aromatic amine is preferably an alicyclic amine. : Aromatic amine=55:45 to 99:1, and more preferably 60:40 to 95:5.
Then, the mixed amine and the diisocyanate compound can be reacted under various methods and conditions. It is preferable to react in a base oil because a diurea compound having a thickening agent with high uniform dispersibility can be obtained. The reaction may be carried out by adding a base oil in which a diisocyanate compound is dissolved to a base oil in which a mixed amine is dissolved, or a base oil in which a mixed amine is dissolved in a base oil in which a diisocyanate compound is dissolved. You may add and do. The temperature and time in these reactions are not particularly limited and may be the same as in ordinary reactions of this type. The reaction temperature is preferably 60°C to 170°C from the viewpoint of solubility and volatility of the mixed amine and diisocyanate. The reaction time is preferably 0.5 to 2.0 hours from the viewpoint of completing the reaction between the mixed amine and the diisocyanate and improving the efficiency by shortening the production time.

Moreover, the compounding amount of the thickener is preferably 10 to 25% by mass, and more preferably 12 to 23% by mass based on the total amount of the grease G.
As the additive, essential components include phosphite, ether compounds and oxidized paraffin, and as optional components, extreme pressure agents, rust preventives, antioxidants, antiwear agents, dyes, hue stabilizers, Examples include various additives such as thickeners, structure stabilizers, metal deactivators, and viscosity index improvers. As the extreme pressure agent, sulfur compounds (zinc dithiocarbamate (ZnDTC), etc.), chlorine compounds (chlorinated paraffin, etc.), molybdenum dithiocarbamate (MoDTC), organic Mo compounds such as molybdenum dithiophosphate (MoDTP), etc. are optional. It may be used as an ingredient.

Examples of the phosphite include triisopropyl phosphite, diisopropyl phosphite, diphenyl hydrogen phosphite, and the like. Particularly, diphenylhydrogen phosphite is preferable.
Further, the blending amount of the phosphite ester is preferably 0.2 to 5 mass% and more preferably 0.3 to 4 mass% with respect to the total amount of grease G.

An ether compound is used as an essential component. The ether compound preferably includes an ether compound having a polar group in the molecule, more preferably an ether compound having a polar group at the end of the molecule, and particularly preferably at the end of the molecule. An ether compound having a polar group consisting of a 5-membered ring having at least one hetero atom can be mentioned. If the ether compound has a polar group, the polar group is attracted to the surface film derived from the polar phosphite ester formed by the reaction with the bearing raceway surface (metal surface). As a result, the oil film of the ether compound can be favorably formed on the surface film of the phosphorus compound, since it is easily adsorbed.

Examples of the ether compound having a polar group consisting of a 5-membered ring having at least one hetero atom at the end of the molecule include a sulfolane derivative represented by the following general formula (1).

(In the formula, R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, and R ² and R ³ each represent hydrogen or a hydrocarbon group having 1 to 20 carbon atoms.)
Further, the blending amount of the ether compound is preferably 0.2 to 5% by mass, and more preferably 0.5 to 4% by mass based on the total amount of the grease G.
Oxidized paraffin is used as an essential component. Examples of the oxidized paraffin include petroleum wax such as paraffin wax and microcrystalline wax, and those obtained by oxidizing synthetic wax such as polyethylene wax. Moreover, the blending amount of the oxidized paraffin is preferably 0.5 to 10 mass% with respect to the total amount of the grease G.

Then, the grease G is prepared by mixing, for example, a base oil as an essential component, a urea compound (thickener), a phosphite ester, an ether compound and paraffin oxide and, if necessary, other additives and stirring. After that, it can be obtained by passing it through a roll mill or the like.
As described above, according to the hub unit 1, since the grease G contains the poly-α-olefin having a kinematic viscosity of 20 to 60 mm ² /s (40° C.) as the base oil, the rotational torque of the rolling element 14 can be reduced. Therefore, even if the absolute value of the negative value of the internal clearance between the rolling element 14 and the outer ring raceway surfaces 11a and 11b and the inner ring raceway surfaces 13a and 13b is increased, the rotational torque can be kept relatively small. .. Therefore, the rigidity can be improved while suppressing an increase in the rotation torque of the hub unit 1. Further, the fretting property can be improved by increasing the absolute value of the negative value of the internal clearance.

The present invention is not limited to the above embodiment, and can be implemented in other embodiments.
For example, in the above-described embodiment, an example in which the grease G is filled in the rolling bearing 2 configured by the (double row) ball bearing has been described, but the bearing in which the grease G is filled is not a ball as a rolling element. Other rolling bearings such as needle bearings, roller bearings, etc., may be used.

In addition to the hub unit 1 described above, the bearing in which the grease G is enclosed may be mounted on another vehicle rolling device such as a suspension unit or a steering unit.
In addition, various design changes can be made within the scope of the matters described in the claims.

Next, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.
-Example 1 and Comparative Example 1
<Preparation of grease>
As the grease of Example 1, the base oil was a synthetic oil (polyα-olefin), the kinematic viscosity of the base oil was 30 mm ² /s (40° C.), the traction coefficient was −0.0063, and the pour point was −65° C. I prepared the grease. This grease comprises 81% by mass of base oil, 15% by mass of urea compound serving as a thickener, 1% by mass of phosphite (diphenyl hydrogen phosphite), sulfolane derivative (the above-mentioned general formula) based on the total amount of grease. In (1), R ¹ contains an alkyl group having 8 carbon atoms, 1% by mass of a compound in which R ² and R ³ are hydrogen, and 2% by mass of oxidized paraffin (petroleum oxide wax). The urea compound used is a compound in which an alicyclic amine (cyclohexylamine) and an aromatic amine (p-toluidine) are mixed at a mass ratio of 70:30 and reacted with a diisocyanate compound (diphenylmethane diisocyanate).

On the other hand, as the grease of Comparative Example 1, a grease in which the base oil is mineral oil, the kinematic viscosity of the base oil is 70 mm ² /s (40° C.), the traction coefficient is −0.0063, and the pour point is −65° C. Got ready. This grease comprises 81% by mass of base oil, 15% by mass of urea compound serving as a thickener, 1% by mass of phosphite (diphenyl hydrogen phosphite), sulfolane derivative (the above-mentioned general formula) based on the total amount of grease. In (1), R ¹ contains an alkyl group having 8 carbon atoms, 1% by mass of a compound in which R ² and R ³ are hydrogen, and 2% by mass of oxidized paraffin (petroleum oxide wax). The urea compound used is an aromatic amine (p-toluidine) reacted with a diisocyanate compound (diphenylmethane diisocyanate).

<Assembly of rolling bearing>
The rolling bearing 2 in which the grease is enclosed was assembled according to the configuration of FIG. During assembly, the preload applied to the rolling elements 14 was adjusted by adjusting the amount of caulking of the caulking portion 8 of the hub wheel 3 with respect to the inner peripheral surface of the inner ring member 12. As a result, rolling bearings 2 having axial gaps (internal gaps) of −0.025 mm, −0.04 mm, −0.055 mm, and −0.08 mm were produced for each of Example 1 and Comparative Example 1. In addition, as Example 1, in order to measure the following rigidity value, a rolling bearing having an axial clearance (internal clearance) of -0.03 mm, -0.05 mm, -0.06 mm, -0.08 mm and -0.1 mm. Also made.

<Evaluation>
(1) Measurement of Bearing (Rotation) Torque Each rolling bearing of Example 1 and Comparative Example 1 was rotated under the conditions of a rotation speed of 800 rpm, a radial load of 5.65 kN, and room temperature, and the torque value after 1 h of rotation was measured. .. The results are shown in Fig. 4. As shown in FIG. 4, it was found that the rotational torque of the bearing of Example 1 (▲) can be reduced by about 40% as compared with the bearing of Comparative Example 1 (●) when the internal clearance is the same.
(2) Measurement of Stiffness Value For each rolling bearing of Example 1, an axial load was applied to the tire ground contact point position under the same conditions, a moment load was applied, and the relative tilt angles of the inner and outer rings were measured.

Results are shown in FIG. In FIG. 5, the rigidity value when the internal gap is −0.05 mm is taken as 100%, and the relative value to the rigidity value is shown. As shown in FIG. 5, it was found that the rigidity value of the bearing can be improved as the absolute value of the negative value of the internal clearance is increased. Combining with the result of FIG. 4, in Example 1, the rotational torque can be kept relatively small even if the absolute value of the negative value of the internal clearance is increased (for example, −0.08 mm). By setting a large absolute value of the negative value of, the rigidity of the bearing can be improved while suppressing an increase in the rotational torque.

DESCRIPTION OF SYMBOLS 1... Hub unit, 9... Large diameter part, 11... Outer ring, 11a... Outer ring raceway surface, 11b... Outer ring raceway surface, 12... Inner ring member, 13a... Inner ring raceway surface, 13b... Inner ring raceway surface, 14... Rolling element, G … Grease

Claims (5)

An outer ring part and an inner ring part,
A rolling element provided between the outer ring portion and the inner ring portion,
Including grease arranged on the rolling surface of the rolling element in the outer ring portion and the inner ring portion,
The gap of the rolling element with respect to the rolling surface is set to a negative gap,
The grease is
A base oil containing a poly-α-olefin and having a kinematic viscosity at 40° C. of 20 to 60 mm ² /s;
A thickener containing a urea compound obtained by reacting a mixed amine of an alicyclic amine and an aromatic amine with a diisocyanate compound,
Containing additives including phosphite ester, ether compounds and oxidized paraffin,
The base oil is
The traction coefficient is 0.02 or less,
A rolling device for vehicles having a pour point of -50°C or lower . An outer ring part and an inner ring part,
A rolling element provided between the outer ring portion and the inner ring portion,
Including grease arranged on the rolling surface of the rolling element in the outer ring portion and the inner ring portion,
The gap of the rolling element with respect to the rolling surface is set to a negative gap,
The grease is
A base oil containing a poly-α-olefin and having a kinematic viscosity at 40° C. of 20 to 60 mm ² /s;
A thickener containing a urea compound obtained by reacting a mixed amine of an alicyclic amine and an aromatic amine with a diisocyanate compound,
Containing additives including phosphite ester, ether compounds and oxidized paraffin,
The ether compound is a rolling device for a vehicle, which has a polar group consisting of a 5-membered ring having at least one hetero atom at a terminal of a molecule . The base oil is
The traction coefficient is 0.02 or less,
The rolling device for vehicles according to claim 2 , which has a pour point of -50°C or lower. The rolling device for a vehicle according to claim 1, wherein the range of the negative gap is −0.06 mm to −0.1 mm . The grease contains 10 to 25% by mass of the thickener, 0.2 to 5% by mass of the phosphite, 0.2 to 5% by mass of the ether compound and 0.5 to 10% of oxidized paraffin. The rolling device for vehicles according to any one of claims 1 to 4, which contains mass%.

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