JP2002147451A - Multiple-row rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of suppressing preload changes caused by changes in temperature in the rotation of driving. SOLUTION: An outer ring seat 20 is provided between a pair of outer rings 8a and 8b. Materials constituting the respective members are so selected that a relation βh>βs>βo is formed among a coefficient of linear expansion βs of a pinion shaft 2 and an inner ring seat 17, a coefficient of linear expansion βh of a support cylinder 13a, and a coefficient of linear expansion βo of the outer ring seat 20. Irrelevant to the changes in the driving state, this constitution can mutually offset an increase of preload based on the generation of the thermal expansion between the respective outer rings 8a and 8b and the respective inner rings 9a and 9b and a decrease in the preload based on the generation of the axial thermal expansion between the pinion shaft 2 and the inner ring seat 17 and between the pinion shaft 2 and the outer ring seat 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A double-row rolling bearing device according to the present invention is a double-row rolling bearing for rotatably supporting, for example, a pinion shaft constituting a differential gear (final reduction gear) of an automobile inside a casing (differential case). Implement as tapered roller bearings.

[0002]

2. Description of the Related Art A differential gear which is provided in the middle of a power transmission system of an automobile to reduce the rotation of a propeller shaft and convert the rotation direction into a right angle at the same time is configured as shown in FIG. Inside front of casing 1 (to the right in FIG. 5)
A pinion shaft 2, which is an inner member described in the claims, is disposed in the portion. A rear end of a propeller shaft (not shown) can be freely connected to a coupling flange 3 fixed at a front end (right end in FIG. 5) of the pinion shaft 2 at a portion protruding from a front end opening of the casing 1. A small reduction gear 4 is fixed to the rear end (left end in FIG. 5) of the pinion shaft 2, and the small reduction gear 4 and the large reduction gear 5 are meshed with each other. The reduction gear 5 is rotatably supported inside a rear portion (left portion in FIG. 5) of the casing 1. The intermediate portion of the pinion shaft 2 is rotatably supported on the casing 1 by a double-row rolling bearing device 6 to which the present invention is applied.

In this double row rolling bearing device 6, a pair of front and rear tapered roller bearings 7a and 7b, which correspond to the first rolling bearing or the second rolling bearing, respectively, are described in the axial direction (FIG. 5). (Left and right directions). Each of these tapered roller bearings 7a and 7b has one outer ring 8a and 8b and one inner ring 9a and 9b, respectively.
It comprises a plurality of tapered rollers 10a and 10b, each of which is a rolling element described in the claims. Conical concave outer raceways 11a and 11b are formed on the inner peripheral surfaces of the outer rings 8a and 8b, and conical convex inner raceways 12a and 12b are formed on the outer peripheral surfaces of the inner races 9a and 9b, respectively. . The outer rings 8a and 8b are connected to the casing 1
And the inner rings 9a and 9b are externally fitted and fixed at two positions before and after the intermediate portion of the pinion shaft 2.

In this state, the end faces of the outer races 8a and 8b facing each other are formed on the inner peripheral surface of a support cylindrical portion 13 provided in the casing 1 and corresponding to the outer member described in the claims. It abuts against the stop portions 14a and 14b.
Therefore, the pair of outer rings 8a and 8b is
Inside, it is fitted and fixed in a state where movement in the direction approaching each other is prevented. On the other hand, the inner rings 9a, 9
The end faces on the opposite side of b are directly connected to the base end face (left end face in FIG. 5) of the fitting cylindrical portion 15 provided with the coupling flange 3 or the base end face (right end face in FIG. 5) of the reduction pinion 4. Or spacer 1
6 through. Therefore, the pair of inner rings 9
Reference numerals a and 9b are externally fitted around the pinion shaft 2 in a state where movement in directions away from each other is prevented.
In the illustrated example, the inner race spacer 17 is sandwiched between the pair of inner races 9a and 9b to ensure the positioning of the inner races 9a and 9b. Also, this inner ring spacer 17
Is provided with a bent portion 18 at an intermediate portion so that the entire length can be elastically contracted.

[0005] A predetermined preload is applied to the double-row rolling bearing device 6 having the above-described configuration. For this reason, in the illustrated example, the fitting tube portion 15 is spline-engaged with the front end of the pinion shaft 2, and
(The right side in FIG. 5) of the tapered roller bearing 7
The inner ring 9a is pressed toward the inner ring 9b of the other (left side in FIG. 5) tapered roller bearing 7b. Thus, a pair of tapered roller bearings 7 constituting the double row rolling bearing 6 is provided.
The preload applied to the a and 7b is set within a range in which the pinion shaft 2 can be supported in the support cylindrical portion 13 without rattling, and the rotational resistance of the double row rolling bearing 6 does not become excessive. If the preload is too small, the pinion shaft 2
However, if the backlash in the support cylindrical portion 13 is too large, the rotational resistance of the double row rolling bearing 6 becomes excessive,
Not only does the fuel efficiency of the vehicle deteriorate, but in severe cases it also causes burn-in due to excessive temperature rise. Therefore, it is important to regulate the preload within an appropriate range.

In the case of the conventional double-row rolling bearing device 6 configured as described above, no special consideration has been given to suppressing a change in preload due to a temperature change. For this reason, depending on the use conditions, favorable characteristics (performance) could not be obtained over the entire use state from a low temperature to a high temperature.
For example, in the case of a differential gear as shown in FIG.
In order to reduce the weight, the entire casing 1 including the support cylinder 13 may be made of a lightweight aluminum alloy. On the other hand, the pinion shaft 2 needs to be made of an iron-based alloy in order to secure required strength and rigidity.
In addition, the constituent members of the tapered roller bearings 7a and 7b are also
In general, it is made of an iron-based alloy such as bearing steel, and in rare cases, some members are made of ceramic.

FIG. 6 is a schematic view showing the double-row rolling bearing 6 taken out of the double-row rolling bearing 6 with respect to the change of the preload accompanying the temperature rise. If the support cylinder 13 is made of an aluminum alloy and the pinion shaft 2 is made of an iron-based alloy, assuming that the temperature between the support cylinder 13 and the pinion shaft 2 uniformly rises with use, the aluminum Due to the difference in the coefficient of linear expansion existing between the alloy and the iron-based alloy, the amount of expansion of the support cylinder 13 becomes larger than the amount of expansion of the pinion shaft 2. A pair of inner rings 9a, 9 which are externally fitted and fixed to the pinion shaft 2 while being prevented from moving in the direction away from each other.
The outer ring 8 is fitted and fixed in a state where the displacement in the direction approaching the support cylinder portion 13 is prevented more than the interval between b.
The distance between a and 8b tends to increase. As a result, the amount of preload of the double row rolling bearing device 6 increases.
When the temperature rises, the amount of increase in the inner diameter of the support cylindrical portion 13 is larger than the amount of increase in the outer diameter of the pinion shaft 2, but
Since the constituent members of the tapered roller bearings 7a and 7b are all made of an iron-based alloy such as bearing steel, the temperature rise of the constituent members of the tapered roller bearings 7a and 7b is uniform. For example, the influence of the dimensional change in the radial direction on the change in the preload amount is small. In other words, when the temperature rises of the constituent members are uniform, the difference in the amount of thermal expansion between the support cylinder 13 and the pinion shaft 2 in the axial direction becomes dominant with respect to the change in preload.

In order to suppress a change in preload due to the above-described causes, Japanese Patent Application Laid-Open No. H10-220468 discloses that a pair of outer rings face each other in order to prevent the pair of outer rings from being displaced in a direction approaching each other. There is described a technique of adopting a structure in which an outer ring spacer is sandwiched between surfaces to be formed, and forming the outer ring spacer from the same material as the pinion shaft. According to such a conventional technique, the amount of expansion of the interval between the pair of outer rings at the time of temperature rise can be suppressed to a low level, so that an increase in the preload amount due to the temperature rise can be suppressed to some extent.

[0009]

The cause of the increase in the preload due to the temperature rise is caused by the difference in the amount of thermal expansion between the outer member such as the support tube portion 13 provided on the housing 1 and the inner member such as the pinion shaft 2. Then, even with the conventional technique described in Japanese Patent Application Laid-Open No. H10-220468, the fluctuation of the preload amount due to the temperature change can be sufficiently suppressed. However, the change in the amount of preload due to the temperature change is caused not only by the difference in the amount of thermal expansion between the outer member and the inner member, but also by the tapered roller bearings 7.
a, 7b, the outer rings 8a, 8b and the inner rings 9a, 9b
It has been found from the study of the inventor that it also occurs due to the difference in the amount of thermal expansion from the above. For this reason, depending on the use conditions, the prior art described in the above publication may not be able to sufficiently suppress the fluctuation of the preload amount.

For example, in the case of a double row rolling bearing device 6 rotatably supporting a pinion shaft 2 constituting a differential gear as shown in FIG. 5, the temperature rise accompanying the continuous rotation of the pinion shaft 2 is radiated. Each inner ring 9a which is difficult
9b, the outer rings 8a, 8b, which are large and easy to dissipate heat because they are in contact with the housing 1 exposed to the outside air, are small. As a result, when the temperature rises, each of these outer rings 8a,
8b, the outer raceways 11a, 11b formed on the inner peripheral surface and the inner raceways 12 formed on the outer peripheral surface of the inner races 9a, 9b.
The diameter difference between a and 12b tends to be small. Reducing the diameter difference leads to an increase in the preload amount of each of the tapered roller bearings 7a and 7b. JP-A-10-220
The prior art described in Japanese Patent No. 468 does not consider such an increase in the preload amount based on the temperature difference generated between the outer rings 8a and 8b and the inner rings 9a and 9b. As described above, there is a possibility that the fluctuation of the preload amount cannot be suppressed sufficiently low. In view of such circumstances, the present invention provides a preload amount that accompanies a temperature change even in an application in which the temperature rise of each of the inner rings 9a and 9b becomes remarkable as compared with the temperature rise of each of the outer rings 8a and 8b during use. It has been invented to realize a double-row rolling bearing device capable of sufficiently suppressing the fluctuation of the bearing.

[0011]

According to the double row rolling bearing device of the present invention, similarly to the above-described conventionally known double row rolling bearing device, the thermal expansion of the inner member and the material constituting the inner member is performed. An outer member made of a material having a coefficient of thermal expansion greater than a coefficient of thermal expansion; and an outer member provided at two axially spaced positions between an inner peripheral surface of the outer member and an outer peripheral surface of the inner member. The first and second rolling bearings allow relative rotation between the member and the inner member. These first,
The second rolling bearing is provided by providing a plurality of rolling elements between the inner raceway provided on the outer peripheral surface of the inner race and the outer raceway provided on the inner peripheral surface of the outer race, and the inner race and the outer race are provided. It can freely support the radial load and the axial load applied between them. Further, a pair of inner races constituting the first and second rolling bearings are externally fitted and fixed to the inner member in a state where the inner races are prevented from moving in directions away from each other. A pair of outer races constituting the rolling bearing are internally fitted and fixed to the outer member in a state where they are prevented from moving in a direction approaching each other. The temperature of the outer member and each of the outer rings is lower than the temperatures of the inner member and the respective inner rings. In particular, in the double row rolling bearing device of the present invention, an outer ring spacer made of a material having a smaller coefficient of thermal expansion than the material forming the inner member is sandwiched between the pair of outer rings. As a result, the amount of change in the preload of the first and second rolling bearings due to the temperature difference between the inner member and the outer member is reduced.

[0012]

According to the double-row rolling bearing device of the present invention configured as described above, when the temperature rises during use, the amount of thermal expansion of the outer ring of each rolling bearing becomes smaller than the amount of thermal expansion of the inner ring. Accordingly, the preload of each of these rolling bearings tends to increase. On the other hand, when the amount of thermal expansion of the outer race spacer is smaller than the amount of thermal expansion of the inner member, the preload of each rolling bearing tends to decrease. As a result, the two behaviors related to the preload fluctuation cancel each other, and the preload fluctuation of each of the rolling bearings due to the temperature rise can be suppressed to a small value.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tapered roller bearing according to an embodiment of the present invention.
The temperature rise of the outer rings 8a and 8b constituting the inner ring 9b
The reason why the preload fluctuation can be kept low even when the temperature is lower than the temperature rises of a and 9b will be described.

FIG. 1 is a schematic view of a double row rolling bearing device 6a according to the present invention. This double row rolling bearing device 6a
As in the case of the conventional structure described above, a pair of front and rear tapered roller bearings 7a and 7b, which correspond to the first rolling bearing or the second rolling bearing, respectively, are described in the axial direction (FIG. 1). (Left and right directions). Each of these tapered roller bearings 7a, 7b is composed of one outer ring 8a, 8b and one inner ring 9a, 9b, and a plurality of tapered rollers 10a, 10b, each of which is a rolling element described in the claims. ing. A conical concave outer raceway 11 is provided on the inner peripheral surface of each of the outer races 8a and 8b.
The inner rings 9a and 9b are formed on the outer peripheral surfaces of the inner rings 9a and 9b with conical convex inner ring tracks 12a and 12b, respectively. The outer rings 8a and 8b are fixedly fitted inside a part of the casing 1, and the inner rings 9a and 9b are fixedly fitted at two positions in front and rear of an intermediate portion of the pinion shaft 2.

In this state, between the end faces of the outer races 8a and 8b facing each other, a support tubular portion 13 provided in the casing 1 and corresponding to an outer member according to the present invention.
A flange portion 19 having an inward flange shape formed on the inner peripheral surface of a and a cylindrical outer ring spacer 20 are sandwiched without any gap. Therefore, the pair of outer rings 8a and 8b are fixedly fitted in the support cylinder portion 13a in a state where the pair of outer rings 8a and 8b are prevented from moving toward each other. On the other hand, the end faces of the inner rings 9a and 9b opposite to each other abut against a member fixed to the pinion shaft 2. Therefore, the pair of inner rings 9a, 9
b is externally fitted and fixed around the pinion shaft 2 in a state where movement in directions away from each other is prevented. In the illustrated example, the inner race spacer 17 is sandwiched between the pair of inner races 9a and 9b to ensure the positioning of the inner races 9a and 9b.

In particular, the double-row rolling bearing device 6a of the present invention
In this case, the pinion shaft 2 and the inner ring spacer 17 are made of steel.
(Linear expansion coefficient β_s = 12.5 × 10^-6Linear expansion)
It is made of metal material with an intermediate ratio. In addition, the support cylinder
13a was converted to an aluminum alloy (linear expansion coefficient β_h = 23.5
× 10^-6Metal) with a large coefficient of linear expansion
ing. Further, the outer ring spacer 20 is connected to an invar (linear expansion).
Tension β_o = 1.2 × 10 ^-6Linear expansion coefficient is small.
It is made of a metallic or ceramic material.
That is, in the case of the double row rolling bearing device 6a of the present invention,
Linear expansion coefficient β of each member 2, 17, 13a, 20_s , Β
_h , Β_o Between each other, β_h > Β_s > Β_o Holds
These members 2, 17, 13a, and 20 are configured so that
We are selecting materials to be used. In addition, each tapered roller shaft
Each of the outer rings 8a, 8b and inner ring constituting the bearings 7a, 7b
9a, 9b and tapered rollers 10a, 10b are all
Like bearing steel, the coefficient of linear expansion is about the same as that of the above-mentioned pinion shaft 2.
It is made of a certain metal material.

As described above, the double row rolling bearing device 6 of the present invention
In the case of a, for the linear expansion coefficient of said outer ring spacer 20 beta _o is made by a small material, each tapered roller bearing 7a with increasing temperature, the preload variations in 7b, it is possible to suppress. That is, in the case of the double row rolling bearing device 6a of the present invention, the pinion shaft 2 and the inner rings 9a,
The temperature rise of 9b becomes more remarkable than the temperature rise of the support cylinder 13a and each of the outer rings 8a and 8b, and a difference occurs in the amount of thermal expansion of each part. Among them, the fact that the amount of thermal expansion of each of the inner rings 9a, 9b is larger than the amount of thermal expansion of each of the outer rings 8a, 8b acts in the direction of increasing the preload of each of the tapered roller bearings 7a, 7b. On the other hand, the outer ring spacer 20 is compared with the thermal expansion amount of the pinion shaft 2 in the axial direction.
The small amount of thermal expansion in the axial direction acts in the direction of decreasing the preload. Therefore, if the size and material (linear expansion coefficient) of each member are appropriately regulated, both of the behavior (increase and decrease) related to the preload fluctuation will be satisfied as long as the following condition regarding the temperature rise of each part during operation is satisfied. Can be offset from each other, and the preload fluctuation of each of the tapered roller bearings 7a and 7b due to the temperature rise can be suppressed to a small value.

The conditions relating to the temperature rise of each part during the operation described above are as follows. That is, as described above, the degree of increase in the preload based on the occurrence of the difference in the amount of thermal expansion between each outer ring 8a, 8b and each inner ring 9a, 9b is as follows.
The temperature difference ΔT between each of the outer rings 8a, 8b and each of the inner rings 9a, 9b increases in proportion to the temperature difference ΔT. On the other hand, as described above, the degree of decrease in the preload based on the difference in the amount of thermal expansion in the axial direction between the pinion shaft 2 and the outer ring spacer 20 and between the support cylinder portion 13a depends on the degree of the double-row rolling bearing device. It increases in proportion to the average temperature T of the whole 6a. Therefore, regardless of the temperature change during operation, in order to effectively cancel both the behavior (rise and fall) related to the preload fluctuation, the ratio of the temperature difference {T and the average temperature T} It is necessary that T / T does not change significantly during operation.

Under such conditions, the present inventor has found that in the case of a bearing device which is operated in a state where the rotational speed and the magnitude of the axial load to be applied are in proportion to each other, the operating state changes in this manner. It is considered that the ratio ΔT / T greatly changes with the operation. On the other hand, in the case of a bearing device that is operated in a state where the rotational speed and the magnitude of the axial load to be applied are substantially inversely proportional to each other, such as a double-row rolling bearing device 6a incorporated in a differential gear, It was considered that the ratio ΔT / T did not change significantly even when the operating state changed.

Therefore, the present inventor conducted an experiment to confirm that such a guess was correct. Hereinafter, this experiment will be described. In this experiment, an experimental device as shown in FIG. 2 was provided with a reference number HR30306 (inner diameter = 30 mm, outer diameter =
Tapered roller bearing 7b having a diameter of 72 mm, overall axial dimension = 20.75 mm, axial dimension of the inner ring = 19 mm, axial dimension of the outer ring = 14 mm), and another tapered roller bearing 7a for support.
Are combined in a state where the contact angles are reversed to form a double-row rolling bearing, and the rotating shaft 22 is supported in the housing 21 by the double-row rolling bearing. Then, while changing the operating condition of the rotating shaft 22 from low rotation / high torque to high rotation / low torque, the tapered roller bearing 7b
The temperature T _i of the temperature T _o and the inner ring 9b of the outer ring 8b constituting was measured. In addition, the average temperature T of the entire double row rolling bearing device
It was measured as the temperature T _o of the outer ring 8b (T = T _o). The reason for this is that the relationship of T _i > T _o > T _{h exists} between the temperature T _{i of the} inner ring 9b, the temperature T _{o of the} outer ring 8b, and the temperature T _{h of the} housing 21 constituting the double-row rolling bearing device 6a. There is, the temperature T _o of the outer ring 8b is an intermediate temperature,
This is because the average temperature T of the entire double row rolling bearing device can be approximated.

The low-rotation / high-torque driving state refers to a state in which the vehicle is running at a low speed with a large reduction ratio of the transmission. The high-rotation / low-torque driving state refers to a state in which the vehicle has a small reduction ratio. (Or by increasing the speed increase ratio) to correspond to a high-speed running state. In the case of the double-row rolling bearing device 6a incorporated in the differential gear, as the torque transmitted through the differential gear increases, the pinion shaft 2 (FIG. 1) moves from the meshing portion of the reduction small gear 4 and the reduction gear 5 (FIG. 5). Axial load applied to the tire increases. Therefore, in the above experiment, a large axial load was applied when the rotating shaft 22 was rotating at a low speed, and a small axial load was applied when the rotating shaft 22 was rotating at a high speed. More specifically, in order to adapt to the actual operation state,
Is varied in the range of 3600 to 9500 min ^-1 (rpm), and the axial load applied to the rotating shaft 22 is adjusted to 7100 to 1370 in accordance with this.
It was changed in the range of 0N. Further, the signals representing the temperatures of the inner rings 9a and 9b can be taken out through the slip ring 23. Other test conditions are as follows. Lubricating oil: Gear oil (180 cSt / 40 ° C) Lubrication amount: 1000 cc / min

The results of the experiments performed in this way are shown in the following Table 1 and FIG.

[Table 1] FIG. 3A shows the results of the experiment shown in Table 1.
FIG. 3B shows the experimental results when the rotational speed was set to 3600 min ^-1 and the axial load to be applied was set to 13700 N. The figure (B) shows the case where the rotational speed was set to 9500 min ^-1 and the axial load applied was set to 7100 N. Are shown by graphs at the time of measurement.

As is clear from the results shown in Table 1 and FIG. 3, the temperature difference ΔT (= T _o −T _i ) between the outer rings 8a and 8b and the inner rings 9a and 9b, and double-row rolling The ratio ΔT / T to the average temperature T of the entire bearing device 6a is 0.4 to
0.75 (ie, 0.4 ≦ △ T / T _o ≦ 0.75);
It could be confirmed that it changed only in a narrow range. Therefore, the double-row rolling bearing device 6a incorporated in the differential gear
In the case of (1), if the dimensions and materials (linear expansion coefficients) of the respective members are appropriately regulated, both of the behaviors (increase and decrease) related to the preload fluctuation can be effectively canceled each other regardless of the change in the operation state. The tapered roller bearings 7a, 7
The preload fluctuation of b can be suppressed to a small value.

Next, a method for appropriately regulating the dimensions and materials (linear expansion coefficients) of the respective members as described above will be described with reference to FIG. 4 in addition to FIG. First, a temperature difference ΔT is generated between the outer rings 8a, 8b and the inner rings 9a, 9b, and the outer rings 8a, 8b and the inner rings 9 are formed.
a, 9b, the amount of reduction Δr in the radial gap of each of the tapered roller bearings 7a, 7b when a difference in the amount of thermal expansion occurs.
Is represented by Δr = Dβ _s ΔT --- (1) Incidentally, in the equation (1), D: the above tapered roller bearing 7a, diameter of 7b beta _s: the outer ring 8a, 8b and the inner ring 9a, the linear expansion of 9b (and the pinion shaft 2 and the inner ring spacer 17) Rate.

Further, the average temperature T of the entire double row rolling bearing device 6a rises, and the pinion shaft 2 and the inner race spacer 17 are increased.
When there is a difference in the amount of thermal expansion in the axial direction between the outer race spacer 20 and the support cylindrical portion 13a, the increase amount Δa of the axial gap of the double row rolling bearing device is represented by Δa = ΔLβ _s - represented by _{(L-L o) β h} -L o β o} T --- (2). In the equation (2), L: distance between the pair of outer rings 8a, 8b _Lo : axial dimension of the outer ring spacer 20 _βs : pinion shaft 2 and inner ring spacer 17 (and the above) The linear expansion coefficient β _{h of the} outer rings 8a, 8b and the inner rings 9a, 9b): the linear expansion coefficient β _o of the support cylinder 13a: the linear expansion coefficient of the outer ring spacer 20.

On the other hand, assuming that the contact angle between the tapered roller bearings 7a and 7b is α, these tapered roller bearings 7a and 7b
The following relationship holds between the variation Δr of the radial gap b and the variation Δa of the axial gap b. Δa = Δr · cotα (3) Accordingly, the conditional expression for canceling out the increase in the preload due to the decrease in the radial clearance and the decrease in the preload due to the increase in the axial clearance is as follows: From the above equations (1) to (3), it is given as follows.

(Equation 1) Note that x on the left side of the equation (4) represents the pair of outer rings 8a,
It represents the ratio L _o / L of the axial dimension L _o of 8b distance L and the outer ring spacer 20 between each other.

On the other hand, actually, the above experimental results (Table 1)
As shown in FIG. 5, the temperature difference ΔT between the outer wheels 8a, 8b and the inner wheels 9a, 9b is changed with the change of the driving state.
When the ratio △ T / T and the average temperature T of the entire double row rolling bearing device 6a is a narrow range _{(0.4 ≦ △ T / T o} ≦ 0.7
It changes in 5). Therefore, the range of change of the ratio ΔT / T (0.4 ≦ ΔT / T _o ≦ 0.7
By substituting 5), the following relational expression can be obtained in accordance with the actual driving situation.

(Equation 2) Therefore, the dimension L of each member is set so as to satisfy the equation (5).
If L _o , D, α and the materials (linear expansion coefficients β _s , β _h , β _o ) are determined, the increase in the preload due to the decrease in the radial gap and the axial gap can be determined irrespective of the change in the operating state. The decrease in the preload due to the increase can be effectively offset each other. And the preload fluctuation of each of the tapered roller bearings 7a and 7b due to the temperature rise can be suppressed small.

When the present invention is carried out, the dimensions L, _Lo , D, α and the materials (linear expansion coefficient β)
_s , β _h , β _o ), the distance L between the pair of outer rings 8a, 8b, the diameter D and the contact angle α of each of the tapered roller bearings 7a, 7b, and the outer rings 8a, 8b The linear expansion coefficient β _s of the inner rings 9 a and 9 b, the pinion shaft 2 and the inner ring spacer 17, and the linear expansion coefficient β _h of the support cylindrical portion 13 a are respectively determined by the design of the double row rolling bearing device 6 a to be incorporated in the differential gear. Often determined at an early stage. Therefore, in many cases where the present invention is implemented, for each of the known values L, D, α, β _s , and β _h , the distance between the outer rings is determined so as to satisfy the above equation (5). The axial dimension _Lo and the material (linear expansion coefficient _βo ) of the seat 20 are determined.

In the above equation (4), D / L ·
The value of ΔT / T · cotα is a plurality of types of double row rolling bearing devices 6a having different specifications (each of the diameter D, the distance L, and the contact angle α) which may be actually used. By calculating, it can be confirmed that the value falls within a predetermined range. Thus, for four types of double-row rolling bearing devices 6a having different specifications that may be actually used in this way, the result of calculating the value of D / L △ ΔT / T ・ cotα is shown below. Are shown in Table 2 below.

[Table 2]

As shown in Table 2, the D / L · ΔT /
The value of T · cotα was in the range of 0.4 to 2.41. Therefore, this D / L △ T
/ T ・ cotα range (0.4 ≦ D / L △ T / T ・ c
otα ≦ 2.41), the following relational expression is obtained.

(Equation 3)

The meaning of the equation (6) is as described above.
This is the same as in the case of equation (5). However, this equation (6) is used.
When using, each of the above diameter D, distance L, and contact angle α
The size is determined by the axial dimension L of the outer ring spacer 20._o And material
(Linear expansion coefficient β_o ) Must be taken into account when calculating when determining
Disappears. Therefore, the axial dimension L of the outer race spacer 20
_o And material (linear expansion coefficient β_o Easy calculation to determine
become.

The applicable range of the double-row rolling bearing device of the present invention is not limited to the double-row rolling bearing device used by being incorporated in the differential gear of the automobile as described above.
The double row rolling bearing device of the present invention is used in a state where the rotational speed and the magnitude of the applied load are substantially inversely proportional to each other, and the ratio between the temperature difference ΔT between the inner and outer rings and the average temperature T of the entirety. The present invention is applicable to all double row rolling bearing devices in which ΔT / T does not change significantly during operation. Therefore, for example, the present invention can also be applied to a double-row rolling bearing device used by being incorporated in a transmission of a machine tool. Further, when implementing the double row rolling bearing device of the present invention, as the first and second rolling bearings,
The present invention is not limited to the tapered roller bearing as in the above-described example, and various types of bearings that can be used in the fixed position preloading system, such as an angular ball bearing and a deep groove ball bearing, can be employed. Further, the types of the first and second rolling bearings, the dimensions of the respective portions, and the like can be different between these two rolling bearings. Furthermore, even when two different types of rolling bearings are combined and implemented, the same effect as in the above-described example can be obtained.

[0033]

Since the present invention is constructed and operates as described above, a double-row rolling bearing device capable of suppressing a change in preload during operation to a small extent is realized. The performance and reliability of the mechanical device can be improved.

[Brief description of the drawings]

FIG. 1 is a half sectional view schematically showing an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an experimental device for confirming a state of a temperature change during operation.

FIG. 3 is a measurement graph showing a part of an experimental result.

FIG. 4 is a half sectional view of a tapered roller bearing, in which the size of an internal gap is exaggerated.

FIG. 5 is a sectional view of a differential gear incorporating one example of a conventional structure.

FIG. 6 is a half sectional view schematically showing an example of a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Pinion shaft 3 Coupling flange 4 Reduction gear 5 Reduction large gear 6 and 6a Double row rolling bearing device 7a, 7b Tapered roller bearing 8a, 8b Outer ring 9a, 9b Inner ring 10a, 10b Tapered roller 11a, 11b Outer ring track 12a, 12b Inner ring raceway 13, 13a Supporting tube portion 14a, 14b Locking step portion 15 Fitting tube portion 16 Spacer 17 Inner ring spacer 18 Bent portion 19 Flange portion 20 Outer ring spacer 21 Housing 22 Rotating shaft 23 Slip ring

Continued on the front page F term (reference) 3J012 AB11 BB03 CB10 DB14 FB12 HB02 3J101 AA16 AA25 AA42 AA54 AA62 BA77 EA51 FA41

Claims (1)

[Claims] 1. An inner member, an outer member made of a material having a higher coefficient of thermal expansion than a material forming the inner member, an inner peripheral surface of the outer member, and an outer periphery of the inner member. First and second rolling bearings provided at two positions axially separated from the surface and permitting relative rotation between the outer member and the inner member, and the first and second rolling bearings are provided. The bearing is provided by providing a plurality of rolling elements between an inner raceway provided on the outer peripheral surface of the inner race and an outer raceway provided on the inner peripheral surface of the outer race, and is provided between the inner race and the outer race. It is capable of supporting radial loads and axial loads, and constitutes the first and second rolling bearings.
The pair of inner rings are externally fitted and fixed to the inner member in a state where they are prevented from moving in the direction away from each other,
The pair of outer rings constituting the second rolling bearing are internally fitted and fixed to the outer member in a state where they are prevented from moving in a direction approaching each other. In the double row rolling bearing device used in a state where the temperature of the member and each of the outer rings is low, a material having a smaller coefficient of thermal expansion than the material forming the inner member between the pair of outer rings. By sandwiching the manufactured outer ring spacer, the amount of change in the preload of the first and second rolling bearings due to the temperature difference between the inner member and the outer member is reduced. Double row rolling bearing device.