JP2000192951A - Tapered roller bearing and differential using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a friction loss by dislocating the cone center of an outside diameter surface of a tapered roller to the side close to the tapered roller to the axis of an inner ring, and limiting the ratio of dislocation quantity of the inner ring axis and the core center of the tapered roller to an inner ring inside diameter. SOLUTION: In a tapered roller 3 interposed between inner/outer rings 2, 1, the cone center P of an outside diameter surface is dislocated to the side close to the tapered roller 3 to the axis O of the inner ring 2. In dislocation quantity ε of the inner ring axis O and the cone center P, the ratio ε/D of the dislocation quantity ε to an inner ring inside diameter D is set in a range being 0<ε/D<0.0025. The tapered roller 3 has a property of trying to make one's own core center P coincide with the rotational center. Thus, when the cone center P is dislocated to the inner ring 2 side, the tapered roller 3 tries to move in the direction for entering the wedge narrow side to make one's own cone center P coincide with the inner ring axis O being the rotational center. The action reduces contact force between a roller end surface and an inner ring large collar 6 to reduce a friction loss by a slide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tapered roller bearing used for various devices including an automobile, and a differential for an automobile using the same.

[0002]

2. Description of the Related Art The basic design of a tapered roller bearing is shown in FIG.
As shown in the figure, the cone center P of the outer diameter surface of the roller 53
And the center axis O of the inner ring 52 is made to coincide.
If this state is ideally realized, the rollers 53 can roll purely without any slippage. In this case, when a load is applied to the bearing, the roller 53 receives a force from a tapered wedge surface formed by the rolling surfaces of the inner ring 52 and the outer ring 51, so that a component force toward the roller large diameter side is generated. Due to this force, the rollers 53 are pressed against the inner ring large collar 56 to cause friction loss. Further, in the above-described design, since the axial movement of the roller 53 is slow, a corresponding bearing rotation is required for the roller 53 to settle in a proper position. In order to avoid this and positively press the rollers 53 against the inner ring large collar 56 side, it is proposed to intentionally shift the cone center P of the rollers 53 with respect to the inner ring center axis O in a direction farther from the rollers 53. ing.

[0003]

In the case of a tapered roller bearing, there are mainly two possible torques to be consumed. One is roller 5
This is the torque resulting from the rolling frictional resistance between No. 3 and the rolling surface. This always occurs as long as it is a rolling bearing, but since the smallest one is in a pure rolling state, it is considered that the standard design is the smallest, and it increases as the slip increases. The other is the end face of roller 53 and inner ring
This is the torque due to slippage between the six. This energy loss must be considered in two lubricating states. A liquid lubrication state and a boundary lubrication state (mixed lubrication state). In a completely liquid lubricated state, the friction loss is very small because it is a shear force of the liquid, and is proportional to the load but can be regarded as substantially constant within a practical range. On the other hand, in a boundary lubrication state or a mixed lubrication state in which metal contact occurs, the friction coefficient is very large, and the friction loss increases in proportion to the load according to Coulomb-Amonton's law. In a conventional design of a tapered roller bearing, which is a conventional technology, or a design in which the rollers 53 are pressed against the inner ring large collar 56 side due to intentional displacement of the cone center and the rollers are quickly settled, an oil film is inevitably formed. The torque tends to increase under extremely low speed and high load conditions that are difficult to achieve.

An object of the present invention is to provide a tapered roller bearing which can reduce friction loss due to sliding friction between a roller end face and an inner ring large flange, and can reduce torque under extremely low speed and high load conditions where an oil film is not easily formed. is there. Another object of the present invention is
The purpose is to maintain the calmness of the inner ring while shifting the cone center. Still another object of the present invention is to reduce a flange load of a bearing supporting a pinion shaft,
An object of the present invention is to provide an automobile differential that can reduce the rotation torque of a pinion shaft.

[0005]

A tapered roller bearing according to the present invention comprises an outer ring having a conical raceway surface on an inner diameter surface, and an inner ring having a conical raceway surface on an outer diameter surface and flanges at both ends. In a tapered roller bearing having a tapered roller interposed between the raceway surfaces of the inner and outer rings, the cone center of the outer diameter surface of the tapered roller is shifted to a position closer to the tapered roller with respect to the center axis of the inner ring. The ratio ε / D of the deviation ε between the center axis of the inner ring and the cone center of the tapered roller to the inner diameter D of the inner ring is defined as 0 <ε / D <0.0025. According to this configuration, the following operation occurs. That is, the tapered roller has a property of trying to match its own cone center with the center of rotation. Therefore, by shifting the cone center of the tapered roller toward the inner ring side as described above, the tapered roller moves in the direction to enter the narrow side of the wedge in order to match its own cone center with the center of rotation. I do. This action reduces the contact force between the roller end face and the inner ring large collar, and reduces friction loss due to slippage. This effect is more effective under extremely low speed and high load conditions where it is difficult to form an oil film. This reduction in friction loss is due to the shift amount ε
It has been confirmed by experiments that a good result can be obtained by setting the ratio ε / D to the inner ring inner diameter D within the above range.

In the present invention, the initial axial clearance between the tapered rollers and the inner ring large flange in the axial direction of the tapered rollers is set to 0.
Preferably, it is smaller than 4 mm. By making the axial gap smaller than the standard value in this way, good calmness of the inner ring is maintained while shifting the cone center of the tapered rollers.

[0007] The vehicle differential of the present invention comprises:
A pinion shaft provided with a drive pinion is supported by a tapered roller bearing, and the rotation of the drive pinion is input from a gear that meshes with the pinion and transmitted to both side gears. Any of the above tapered roller bearings of the present invention is used as a roller bearing. The bearing that supports the pinion shaft of the vehicle differential,
Both radial load and axial load are applied,
In addition, the use environment becomes severe. For this reason, the practical effect of reducing the flange load and the torque by shifting the cone center P is large.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. This tapered roller bearing is a bearing used for inner ring rotation, and is provided between an outer ring 1 having a conical rolling surface 1a on an inner diameter surface and an inner ring 2 having a conical rolling surface 2a on an outer diameter surface. A plurality of tapered rollers 3 are interposed while being held by the holder 4. The inner ring 2 has a small flange 5 formed at a small diameter end and a large flange 6 formed at a large diameter end. The tapered roller 3 has a conical outer surface with an outer surface along the rolling surface 1 a of the outer ring 1 and the rolling surface 2 a of the inner ring 2.

Tapered roller 3 interposed between inner and outer rings 2 and 1
Shifts the cone center P on the outer diameter surface toward the tapered roller 3 with respect to the center axis O of the inner ring 2. The deviation ε between the inner ring center axis O and the cone center P is the deviation ε
Ε / D with respect to the inner ring inner diameter D is in the range of 0 <ε / D <0.0025. The initial axial gap δ between the tapered roller 3 and the inner ring large flange 6 shown in FIG. 3 in the tapered roller axis direction is set to be smaller than 0.4 mm.

According to the tapered roller bearing having this configuration, the following operation occurs. That is, the tapered roller 3 has a property of trying to match its own cone center P with the center of rotation.
Therefore, by shifting the cone center P of the tapered roller 3 toward the inner ring 2 as described above, the tapered roller 3
In order to make its own cone center P coincide with the center axis O of the inner ring, which is the center of rotation, an attempt is made to move in a direction to enter the narrow side of the wedge. The action reduces the contact force between the roller end face and the inner ring large flange 6, and reduces the friction loss due to slip. This effect is more effective under extremely low speed and high load conditions where it is difficult to form an oil film. In addition, if the sliding friction surface is completely liquid lubricated, in this embodiment, contrary to this embodiment, even when the cone center is displaced away from the inner ring as described above as the conventional example, the liquid shear There is only a loss due to force, and there is no big difference.

Also, in order to shift the cone center P as shown in the present invention with respect to the standard bearing in which the cone center P coincides with the rotation center O shown in FIG. 9, the taper angle of the tapered rollers 3 and the inner and outer rings In addition to changing both the taper angles of the rolling surfaces 2 and 1, as shown in FIG. 4, while maintaining the taper angle θw of the tapered rollers 3, the taper angle θ of the rolling surface of the inner ring 2 is changed to change the cone center. P may be shifted.

Next, each experimental example will be described. [Experimental Example 1] In a tapered roller bearing in which the cone center P is shifted as in the example of FIG.
FIG. 5 shows the torque measurement data for the case of 0.0025 and the tapered roller bearing with the standard ε / D = 0, which eliminates this deviation. From the figure, it can be seen that the torque of the bearing with ε / D = 0.0025 is lower in the low speed region where the oil film is not easily formed. FIG. 6 shows the rotational torque when ε / D is changed. As shown in FIG.
It can be seen that the low-speed torque in the case of 0025 or less is small.

[Experimental Example 2] If the shift amount ε is shifted in the direction in which the low-speed torque decreases, the effect of the shift is that the settling of the inner ring at the time of assembling the tapered roller bearing deteriorates. This is a demerit of the result of realizing low torque by making it difficult for the tapered rollers 3 to go to the inner ring large collar 6. In the tapered roller bearing, the inner ring settling property is a very important property. Therefore, a configuration for reducing the low-speed torque by making it the same as the conventional one will be described below. FIG. 7 shows the measurement results of inner ring calmness. If ε / D is a positive value, it takes a lot of rotation until the inner ring 2 is completely settled. This is improved by making the axial clearance between the tapered rollers 3 and the inner raceway contact surface smaller than the standard.

In conjunction with FIG. 3, a proper initial axial clearance δ
Will be described. FIG. 3 is an exaggerated representation, but the point at which the inner race 2 is completely settled is the point Q where the roller large diameter end face and the inner race large collar 6 come into contact. That is, if the initial axial gap δ is small, the amount of movement of the tapered rollers 3 can be small, so that the number of rotations required for calm down also decreases. For example, in the experimental results shown in FIG. 7, since the inner ring subsidence amount when ε / D = 0.0025 is 50 μm for 5 rotations, if the initial axial gap δ is 50 μm, ε / D = 0.0
Even if it is 025, it can be completely settled by 5 rotations. Therefore, a tapered roller bearing having an initial axial gap δ smaller than the standard and 0 <ε / D <0.0025 can reduce torque and have good inner ring settling properties.

FIG. 8 shows a differential for an automobile using the tapered roller bearing of the present invention. The vehicle differential 30 is a pinion shaft 3 composed of a propeller shaft.
1 transmits the rotation of the drive pinion 32 to the left and right side gears 39 and 40 via a ring gear 33, a differential case 34, a pair of clutch members 35 and 36, and pinions 37 and 38. Pinion shaft 31 provided with drive pinion 32
Is supported by a housing 45 via a plurality of tapered roller bearings 41 and 42. The side gears 39, 40 are provided on the pinion shafts 45, 46, respectively.
5 and 46 are supported by a housing 45 via tapered roller bearings 43 and 44. The tapered roller bearing of the present invention (the bearing of the embodiment of FIG. 1 in this example) is used as the bearings 41 and 42 for supporting the pinion shaft 31 composed of the propeller shaft. Tapered roller bearings such as the example of FIG. 1 of the present invention may also be used as the bearings 43 and 44 for supporting the pinion shafts 45 and 46 of the side gears 39 and 40.

[0016]

According to the tapered roller bearing of the present invention, the cone center on the outer diameter surface of the tapered roller is displaced by a predetermined amount in a direction closer to the tapered roller with respect to the center axis of the inner ring. Friction loss due to sliding friction of
Torque can be reduced under extremely low speed and high load conditions where it is difficult to form an oil film. When the initial axial gap between the tapered rollers and the inner ring large flange in the axial direction of the tapered rollers is made smaller than the standard value of 0.4 mm, the inner ring is kept calm while shifting the cone center. In addition, by setting the hydraulic parameter よ う as described above, the above-described functions and effects can be effectively exerted under conditions where an oil film is not substantially formed, at extremely low speeds and under high load conditions. In addition, since the differential for an automobile according to the present invention uses the tapered roller bearing having the above-described configuration, the effects of reducing the flange load and reducing the rotational torque in the tapered roller bearing can be effectively obtained, and the rotational torque of the pinion shaft can be improved. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tapered roller bearing according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a dimensional relationship of the tapered roller bearing.

FIG. 3 is an explanatory diagram of an initial axial clearance of the tapered roller bearing.

FIG. 4 is a sectional view of a tapered roller bearing according to another embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the rotation speed and the torque for a bearing with and without a cone center shift.

FIG. 6 is a graph showing low-speed rotation torque when the amount of displacement of the cone center is changed.

FIG. 7 is a graph showing inner ring calm data.

FIG. 8 is a sectional view of an automotive differential according to an embodiment of the present invention.

FIG. 9 is a sectional view of a conventional standard type tapered roller bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer ring 1a ... Rolling surface 2 ... Inner ring 2a ... Rolling surface 3 ... Tapered roller 5 ... Inner ring small flange 6 ... Inner ring large flange 31 ... Pinion shaft 32 ... Drive pinion 33 ... Ring gear 39, 40 ... Side gear 41 , 42: tapered roller bearing D: inner diameter of inner ring O: center axis of inner ring P: cone center ε: displacement

Claims (3)

[Claims] 1. An outer ring having a conical raceway surface on an inner diameter surface, an inner ring having a conical raceway surface on an outer diameter surface and flanges at both ends, and a cone interposed between the raceway surfaces of the inner and outer rings. In a tapered roller bearing provided with rollers, the cone center on the outer diameter surface of the tapered roller is displaced closer to the tapered roller with respect to the center axis of the inner ring, and the center axis of the inner ring and the cone center of the tapered roller are shifted. A tapered roller bearing wherein the ratio ε / D of the displacement ε to the inner ring inner diameter D is 0 <ε / D <0.0025. 2. The tapered roller bearing according to claim 1, wherein an initial axial gap between the tapered roller and the inner ring large flange in the axial direction of the tapered roller is smaller than 0.4 mm. 3. A differential for an automobile, wherein a pinion shaft provided with a drive pinion is supported by a tapered roller bearing, and rotation of the drive pinion is input from a gear meshing with the pinion and transmitted to side gears on both sides. An automotive differential using the tapered roller bearing according to claim 1 as a tapered roller bearing for supporting a shaft.