JP2013124761A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a rolling bearing in which damage, such as early exfoliation, is unlikely to occur on an outer ring track 6, an inner ring track 7, and the raceway surfaces of rolling elements 8, 8 constituting rolling contact parts, and which is capable of suppressing a creep phenomenon between an outer ring 4 and a counterpart member.SOLUTION: In the rolling bearing comprising an outer ring having an outer ring track on the inner circumferential surface, an inner ring having an inner ring track on the outer circumferential surface, and a plurality of rolling elements rotatably provided between the outer ring track and the inner ring track, and used by internally fitting and supporting the outer ring on a fixed portion and externally fitting and supporting the inner ring on a rotating portion, if the minimum thickness of the portion where the outer ring track is provided at the center part in the axial direction of the outer ring is h, and the diameter of each of the rolling elements is Da, 0.4Da≤h≤0.8Da is satisfied and the width of the outer ring is 1.2 Da or more, and to the outer circumference of the outer ring, an elastic body is attached.

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing that can suppress the occurrence of a creep phenomenon and is suitable for supporting a rotating shaft of a belt type continuously variable transmission of an automobile.

  Various types of belt-type continuously variable transmissions have been conventionally considered as transmission units for automatic transmissions for automobiles, as described in, for example, Japanese Utility Model Publication No. 8-30526, and some of them are actually used. ing. FIG. 2 schematically shows the basic structure of such a belt type continuously variable transmission. This belt-type continuously variable transmission has an input side rotating shaft 1 and an output side rotating shaft 2 arranged in parallel to each other. Each of these rotary shafts 1 and 2 is rotatably supported by a pair of rolling bearings 3 and 3 respectively inside a transmission case (not shown) which is a fixed portion described in the claims. .

  Each of these rolling bearings 3 and 3 has an outer ring 4 and an inner ring 5 provided concentrically with each other, as shown in detail in FIG. Of these, the outer ring 4 has an outer ring raceway 6 on the inner peripheral surface, and the inner ring 5 has an inner ring raceway 7 on the outer peripheral surface. A plurality of rolling elements 8, 8 are provided between the outer ring raceway 6 and the inner ring raceway 7 so as to roll freely while being held by a cage 9. Each of the rolling bearings 3 and 3 configured as described above has the outer ring 4 fitted and fixed to a part of the transmission case, and the inner ring 5 is connected to the input side rotary shaft 1 or the output. The side rotary shaft 2 is externally fitted and fixed. And by this structure, these both rotating shafts 1 and 2 are rotatably supported inside the said transmission case. Conventionally, as the rolling bearings 3 and 3, the outer ring 4, the inner ring 5 and the rolling elements 8 and 8 made of two types of general bearing steel (SUJ2) have been used.

  Of the rotary shafts 1 and 2, the input-side rotary shaft 1 is rotationally driven by a driving source 10 such as an engine via a starting clutch 11 such as a torque converter or an electromagnetic clutch. In addition, a driving pulley 12 is provided at a portion located between the pair of rolling bearings 3 and 3 in the intermediate portion of the input side rotating shaft 1, and the driving pulley 12 and the input side rotating shaft 1 are synchronized. To rotate. The distance between the pair of drive side pulley plates 13a and 13b constituting the drive side pulley 12 is determined by displacing one drive side pulley plate 13a (left side in FIG. 2) in the axial direction by the drive side actuator 14. It is adjustable. That is, the groove width of the driving pulley 12 can be expanded and contracted by the driving actuator 14.

  On the other hand, a driven pulley 15 is provided in a middle portion of the output side rotating shaft 2 between a pair of rolling bearings 3 and 3, and the driven pulley 15 and the output side rotating shaft 2 are synchronized. To rotate. The distance between the pair of driven pulley plates 16a and 16b constituting the driven pulley 15 is determined by displacing one (right side in FIG. 2) driven pulley plate 16a in the axial direction by the driven actuator 17. It is adjustable. That is, the groove width of the driven pulley 15 can be expanded and contracted by the driven actuator 17. An endless belt 18 is stretched between the driven pulley 15 and the driving pulley 12. As the endless belt 18, a metal belt is used.

  In the belt-type continuously variable transmission configured as described above, the power transmitted from the drive source 10 to the input-side rotary shaft 1 via the start clutch 11 is transmitted from the drive-side pulley 12 to the endless belt 18. Via the driven pulley 15. Conventionally, as the endless belt 18, one that transmits power in the pressing direction and one that transmits power in the pulling direction are known. In any case, the power transmitted to the driven pulley 15 is transmitted from the output side rotating shaft 2 to the drive wheels 21 and 21 via the reduction gear train 19 and the differential gear 20. When changing the gear ratio between the input-side rotating shaft 1 and the output-side rotating shaft 2, the groove widths of the pulleys 12 and 15 are expanded and contracted while being associated with each other.

  For example, when the reduction ratio between the input-side rotating shaft 1 and the output-side rotating shaft 2 is increased, the groove width of the driving pulley 12 is increased and the groove width of the driven pulley 15 is decreased. To do. As a result, the diameter of the part of the endless belt 18 that spans the pulleys 12 and 15 is small at the driving pulley 12 part and large at the driven pulley 15 part, and the input side rotation Deceleration is performed between the shaft 1 and the output side rotating shaft 2. On the other hand, when increasing the speed increasing ratio between the input side rotating shaft 1 and the output side rotating shaft 2 (decreasing the speed reducing ratio), the groove width of the driving pulley 12 is decreased and the driven side is also decreased. The groove width of the pulley 15 is increased. As a result, the diameter of the portion of the endless belt 18 that spans the pulleys 12 and 15 is larger at the driving pulley 12 portion and smaller at the driven pulley 15 portion, and the input side rotation The speed is increased between the shaft 1 and the output side rotating shaft 2.

  During operation of the belt-type continuously variable transmission constructed and operated as described above, lubricating oil is supplied to each movable part to lubricate each movable part. CVT fluid (including ATF oil) is used as the lubricating oil used in the belt type continuously variable transmission. The reason for this is to increase and stabilize the friction coefficient of the friction engagement portion between the metal endless belt 18 and both the drive side and driven side pulleys 12 and 15. The CVT fluid is circulated through the friction part at a flow rate of 300 ml / min or more to lubricate the friction part. A part of the CVT fluid passes through the rolling bearings 3 and 3 (for example, at a flow rate of 20 ml / min or more) to lubricate the rolling contact portions of the rolling bearings 3 and 3. Therefore, the wear particles generated due to the friction between the endless belt 18 and the pulleys 12 and 15 and the friction at the reduction gear train 19 are generated inside the rolling bearings 3 and 3. There is a high possibility that foreign matters such as gear dust will enter the CVT fluid. Such foreign matters damage the rolling contact portions of the respective rolling bearings 3 and 3 and cause the durability to be lowered.

Therefore, conventionally, each of the above rolling bearings 3
3 or the diameter Da of each of the rolling elements 8 and 8 is increased to increase the basic dynamic load rating of each of the rolling bearings 3 and 3. It had a margin in life. However, if the diameter Da of each of the rolling elements 8 and 8 is increased in order to ensure the basic dynamic load rating, the thickness of the outer ring 4 can be reduced in order to reduce the size and weight of the belt-type continuously variable transmission. T
Must be small (thin). Moreover, when the transmission case for fixing the outer ring 4 has low rigidity, if the thickness T of the outer ring 4 is reduced in this way, the outer ring 4 is easily elastically deformed, and the outer ring 4 is easily deformed. 4
Excessive bending stress may be applied to the rolling bearings 3, and the life of the rolling bearings 3 and 3 may be reduced.

  When such bending stress is repeatedly applied, the outer diameter surface of the outer ring 4 is elastically deformed in a wavy shape according to the passing period of the balls, and the outer ring 4 of the rolling bearings 3 and 3 and the transmission case are Creep phenomenon is likely to occur in the meantime, and even if the life of the rolling bearing is not directly reduced, the life of the rolling bearings 3 and 3 may be reduced due to the influence of wear powder generated by the creep phenomenon, or the case itself The belt wears out and the play in the radial direction becomes large, so that the life of the belt is reduced and the gear meshing system is lowered.

  In general, the outer ring 4 and the transmission case are used with a clearance fit, but when a different external load (gear reaction force, etc.) acts differently from the belt tension direction as in the bearing 3 of FIG. However, depending on the layout, the respective loads may cancel each other out, and the load acting on the bearing may be extremely small, resulting in a state close to no load. In this case, the outer ring may be dragged and rotated by the dynamic friction of the bearing, and creep may be accelerated according to the load fluctuation, resulting in a similar problem.

No. 8-30526

  In view of such circumstances, the present invention fixes the outer ring 4 to the outer ring 4 in the case where the outer ring is fixed to a transmission case with low rigidity, such as made of an aluminum alloy, and particularly when a composite load of two or more directions is applied. The invention was invented to realize a rolling bearing capable of effectively suppressing the creep phenomenon between the machine case and maintaining durability over a long period of time.

  The rolling bearing of the present invention includes an outer ring, an inner ring, and a plurality of rolling elements. Of these, the outer ring has an outer ring raceway on the inner peripheral surface. The inner ring has an inner ring raceway on the outer peripheral surface. Each rolling element is provided between the outer ring raceway and the inner ring raceway so as to roll freely. An elastic body is attached to at least a part of the outer ring outer periphery. Furthermore, in the rolling bearing of the present invention, h is the minimum thickness (thickness in the radial direction) of the portion where the outer ring raceway is provided at the axial center of the outer ring, and the diameter of each rolling element is Da. In this case, 0.4 Da ≦ h ≦ 0.8 Da, more preferably 0.4 Da ≦ h ≦ 0.6 Da is satisfied, and the width of the outer ring is 1.2 Da or more.

  When the rolling bearing of the present invention configured as described above is used as a rolling bearing for a belt-type continuously variable transmission, for example, a CVT fluid having a low viscosity is used, and it is incorporated in a transmission case having low rigidity. However, it is possible to ensure sufficient creep resistance and peeling life. In other words, even when the outer ring is fixed to a transmission case having low rigidity, such as an aluminum alloy, it is possible to prevent the outer ring from being elastically deformed and from being subjected to excessive stress due to this deformation. For this reason, by using a CVT fluid with low viscosity and not allowing a large amount of lubricating oil to flow through the rolling bearing (for example, much higher than 20 ml / min), the outer ring raceway and the inner ring raceway and each rolling element Even when it is difficult to secure the strength of the oil film interposed between the rolling contact portion and the rolling contact surface, it is possible to prevent the occurrence of metal contact at the rolling contact portion and sufficiently ensure the peeling life. Therefore, it is not necessary to increase the size of the rolling bearing in order to ensure the required durability, and the rotation support portion of the input side rotation shaft and the output side rotation shaft can be configured to be small and light, and the rotation resistance can be reduced. Can be planned. As a result, the belt type continuously variable transmission can be reduced in size and weight, and transmission efficiency can be improved.

  Further, the outer ring outer diameter surface is prevented from elastically deforming in a wavy shape according to the ball passing cycle, and an elastic body mounted on the outer ring outer diameter surface is interposed between the bearing outer ring and the transmission case. Therefore, even when loads in two or more directions cancel each other and a state close to no load is reached, creep that occurs between the bearing outer ring and the transmission case can be suppressed.

  Further, by setting the predetermined outer ring width, the contact area with the transmission case is increased, and the creep phenomenon can be suitably suppressed even when the contact load is large.

Sectional drawing similar to FIG. 3 which shows an example of embodiment of this invention. 1 is a schematic cross-sectional view of a vehicle drive system incorporating a belt-type continuously variable transmission including a rolling bearing that is a subject of the present invention. The expanded sectional view which takes out and shows a rolling bearing.

FIG. 1 shows an example of an embodiment of the present invention. The present invention is characterized by a rolling bearing 3a for supporting both the input side and output side rotary shafts 1 and 2 (see FIG. 2) for a belt type continuously variable transmission.
Thus, even when the rigidity of the transmission case is low, the durability of the rolling bearing 3a is sufficiently ensured. The structure and operation of the other parts, including the structure shown in FIG. 3 described above, are the same as those of conventionally known rolling bearings for belt-type continuously variable transmissions. Thus, the overlapping description is omitted or simplified, and the following description will focus on the features of the present invention.

  In the case of this example, when the minimum thickness (with respect to the radial direction) of the portion where the outer ring raceway 6 is provided at the axial center of the outer ring 4a is h and the diameter of each rolling element 8, 8 is Da, 0 The dimension of the outer ring 4a is regulated so as to satisfy 4 Da ≦ h ≦ 0.8 Da, more preferably 0.4 Da ≦ h ≦ 0.6 Da. Further, the width W in the axial direction of the outer ring 4a and the inner ring 5 is restricted to a range satisfying 1.2 Da ≦ W ≦ 2.5 Da. In the case of such a rolling bearing 3a of this example, it is possible to ensure a sufficient peeling life even when a CVT fluid having a low viscosity is used and it is incorporated in a transmission case having low rigidity.

That is, even when the outer ring 4a is fixed to a lightweight but low-rigidity transmission case such as an aluminum alloy, the outer ring 4a is elastic without increasing the thickness h of the outer ring 4a. It can be prevented that the outer ring 4a is deformed or excessive stress is applied to the outer ring 4a. For this reason, the outer ring raceway 6 and the inner ring raceway 7 are connected to each rolling contact by using CVT fluid having a low viscosity and not allowing a large amount of lubricating oil to flow through the rolling bearing 3a (for example, much higher than 20 ml / min). Even when it is difficult to secure the strength of the oil film interposed between the rolling contact surfaces of the moving bodies 8 and 8, it is possible to prevent the metal contact from occurring at the rolling contact portions and ensure a sufficient peeling life. Is possible. Input side rotating shaft 1
In addition, the rotation support portion of the output side rotating shaft 2 can be made small and light, and the rotation resistance can be reduced. As a result, the belt type continuously variable transmission can be reduced in size and weight, and transmission efficiency can be improved. In addition, since the creep phenomenon between the outer ring 4a and the transmission case is also suppressed, the reliability can be greatly improved.

  When the minimum thickness h of the outer ring 4a exceeds 0.8 Da, it is difficult to incorporate the rolling elements 8 and 8 into the rolling bearing 3a. That is, when the rolling bearing 3a is assembled by an automatic assembling apparatus, the rolling element 8 to be assembled last is usually assembled with the outer ring 4a elastically deformed. For this reason, when the minimum thickness h exceeds 0.8 Da, a load necessary for elastically deforming the outer ring 4a increases, and the outer ring 4a and the rolling elements 8, 8 are likely to be damaged, It may not be possible to assemble with automatic assembly equipment. On the other hand, when the minimum thickness h is less than 0.4 Da, the outer ring 4a is easily elastically deformed when the rigidity of the transmission case for fixing the outer ring 4a is low, and the outer ring raceway 6 and the inner ring There is a case where early peeling occurs on the raceway 7 and the rolling surfaces of the rolling elements 8 and 8 and the creep durability is lowered.

  The width W in the axial direction of the outer ring 4a and the inner ring 5 is preferably as large as possible from the viewpoint of preventing elastic deformation of the outer ring 4a and the inner ring 5 and increasing the contact area with the transmission case. However, when the width W is increased, the mass of the outer ring 4a and the inner ring 5 is also increased. That is, when the width W exceeds 2.5 Da, the mass of the outer ring 4a and the inner ring 5 becomes too large, and the transmission efficiency of the belt type continuously variable transmission may be reduced. On the other hand, when the width W is smaller than 1.2 Da, the rigidity of the outer ring 4a and the inner ring 5 is lowered, and the outer ring 4a and the inner ring 5 may be easily elastically deformed. Therefore, the width W is preferably within a range of 1.2 Da to 2.5 Da.

Further, in the case of this example, no seal member is provided at both end openings of the portion where the plurality of rolling elements 8 are installed between the inner peripheral surface of the outer ring 4 and the outer peripheral surface of the inner ring 5. However, the drive side and driven side pulleys 12 and 15 and the endless belt 18 (FIG. 2).
In the case where there is a large possibility that a large amount of foreign matter, such as wear powder, see), the seal member is preferably provided as long as the axial dimension of the rolling bearing permits. As such a seal member, in addition to the TM seal, a metal plate non-contact type, contact type or non-contact type nitrile seal, acrylic seal or fluorine seal is selected and used in consideration of the operating temperature. it can.

  Further, the structure and material of the cage 9 that holds the rolling elements 8 and 8 so as to freely roll are not particularly limited. However, when the rotational speed during use is particularly fast, the crown-type holding made of synthetic resin is used. The use of a cage is preferable from the viewpoint of reducing the friction between the cage and the rolling element and suppressing the generation of hard wear powder and extending the life.

Further, in the case of this example, the outer ring 4a, the inner ring 5, and the rolling elements 8 and 8 constituting the rolling bearing 3a are each composed of two types of bearing steel (SUJ2) having a retained austenite amount γR of 5 to 15% by volume. Yes. However, if there is a large amount of foreign matter that is present in the belt type continuously variable transmission and mixed in the CVT fluid and passes through the installation space of the rolling elements 8, 8 of the rolling bearing 3a, the outer ring 4a, the inner ring 5, It is preferable that the steel material constituting the rolling elements 8 and 8 is subjected to carburizing treatment or carbonitriding treatment. By such treatment, the amount of retained austenite on the surfaces of the outer ring 4a, inner ring 5, and rolling elements 8 and 8 is set to 20 to 45% by volume, and the hardness of the surface is set to about HRC 62 to 67. This surface damage can be prevented, and the durability of the rolling bearing 3a can be improved. Further, when the operating temperature of the rolling bearing 3a reaches 150 ° C. or more, the amount of retained austenite is set to 0 to 5% in the outer ring 4a, the inner ring 5 and the rolling elements 8 and 8.
It is preferable to carry out a dimensional stabilization treatment that suppresses the degree. In this case, it is also preferable to use a seal member provided with a heat resistant rubber.

  Further, the rolling bearing 3a is not limited to the single row deep groove type ball bearing as shown in the figure, and other types of ball bearings such as an angular type, as well as other types such as a cylindrical roller bearing, a tapered roller bearing, a needle bearing, etc. Even in the case of a bearing, similar actions and effects can be obtained.

  Furthermore, in this example, a groove 31 is formed on the outer periphery of the outer ring 4a, and an O-ring 32 is fitted. The relationship between the groove 31 and the O-ring 32 is that the crushing rate of the O-ring (change rate of the O-ring diameter) when the outer ring 4a is fitted into the transmission case and the O-ring is crushed is 10 to 35%. And the filling rate which is the volume which an O-ring occupies with respect to the total volume of the groove | channel 31 in that case is set so that it may become 60 to 95%.

  The O-ring 32 is preferably an elastic body represented by rubber or the like (nitrile rubber, acrylic rubber, fluorine rubber, or the like). Further, the cross-sectional shape of the O-ring can be arbitrarily selected as long as the crushing rate and the filling rate can be maintained. In the embodiment shown in FIG. 1, two grooves 31 are provided. However, the larger the outer diameter of the bearing, the larger the contact area between the elastic body and the case, and the creep resistance is improved. One or three or more may be provided.

  Due to the effect of the O-ring, even if the rolling bearing 3a rotates in a situation where the contact load between the outer ring 4a and the transmission case is small, the occurrence of creep phenomenon between the transmission case and the outer ring 4a can be suppressed. Creep can be prevented over a wide range even under variable load conditions in two directions.

  The rolling bearing of the present invention is excellent in durability and creep resistance, and can be suitably used for various machine elements in addition to a bearing for supporting a pulley shaft of an automobile belt-type transmission.

DESCRIPTION OF SYMBOLS 1 Input side rotating shaft 2 Output side rotating shaft 3, 3a Rolling bearing 4, 4a Outer ring 5 Inner ring 6 Outer ring raceway 7 Inner ring raceway 8 Rolling element 9 Cage 10 Drive source 11 Starting clutch 12 Drive side pulleys 13a, 13b Drive side pulley plate 14 Drive side actuator 15 Drive side pulleys 16a and 16b Drive side pulley plate 17 Drive side actuator 18 Endless belt 19 Reduction gear train 20 Differential gear 21 Drive wheel

Claims (4)

  An outer ring having an outer ring raceway on an inner peripheral surface, an inner ring having an inner ring raceway on an outer peripheral surface, and a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be freely rollable. In a rolling bearing that is supported by internal fitting on a fixed part and supported by external fitting on a part that rotates the inner ring, the minimum thickness of the part provided with the outer ring raceway at the axial center of the outer ring is h. When the diameter of each rolling element is Da, 0.4 Da ≦ h ≦ 0.8 Da is satisfied, and at least one elastic body is mounted on the outer periphery of the outer ring. Rolling bearing.   The rolling bearing according to claim 1, wherein the fit between the fixed portion on which the outer ring is fitted and supported and the outer ring is a clearance fit.   In the state where the outer ring is fixed to the fixed portion where the outer ring is fitted and supported, the crushing rate of the elastic body is 10 to 35%, and the filling rate is 60 to 95%. The rolling bearing according to claim 1 or 2.   The rolling bearing according to claim 1, used as a support on which a composite load in two or more directions acts, and a method for supporting the rolling bearing.

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