JP2006266395A - Rotary supporting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of reducing torque of each ball bearing 3, 3 sufficiently, ensuring a sufficient oil film in a contact part of rolling faces of each ball 9, 9 constituting each ball bearing 3, 3 and each raceway track 4, 6 of an outer ring and an inner ring, and ensuring durability of each contact part sufficiently. <P>SOLUTION: Pre-load load given to each ball bearing 3, 3 is reduced to such extent that gross slip occurs in a contact part of each ball 9, 9 and the raceway track 6 of the inner ring in at least a part of a scope of rotational speed of the inner ring 7 realized when using. At the same time, lubrication conditions of each ball bearing 3, 3 are regulated so as to prevent occurrence of damage and seizure on the rolling faces of each ball 9, 9 and each raceway track 4, 6 of the outer ring and the inner ring during at least desired operation time in the scope of rotational speed at which gross slip occurs. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The rotation support device according to the present invention is incorporated in, for example, a high-speed turbo machine (turbocharger, turbo pump, etc.), a gas turbine, a gear-type transmission, or the like so as to rotatably support a rotating shaft that rotates at high speed with respect to a housing. To use.

  Conventionally, for example, a spindle as shown in FIG. 4 is used as a rotation support device incorporated in various mechanical devices. In this spindle, an intermediate portion of the rotary shaft 1 is rotatably supported by a pair of ball bearings 3 and 3 inside the bearing housing 2. Each of these ball bearings 3 and 3 includes an outer ring 5 having an outer ring raceway 4 on an inner peripheral surface, an inner ring 7 having an inner ring raceway 6 on an outer peripheral surface, and a cage 8 between the outer ring raceway 4 and the inner ring raceway 6. It consists of a plurality of balls 9, 9 provided so as to be able to roll while being held. In the case of the illustrated example, the outer ring 5 is a so-called counter bore in which the shoulder on one side is eliminated.

  Such a pair of ball bearings 3 and 3 externally supports the inner rings 7 and 7 on the intermediate portion of the rotary shaft 1 and also fits the outer rings 5 and 5 to the bearing housing 2 with a clearance fit. It is fitted. In this state, the end faces in the axial direction of the inner rings 7 and 7 are butted against each other, and the annular members 11 and 11 are respectively brought about by the elasticity of the compression spring 10 provided between the pair of outer rings 5 and 5. The outer rings 5 and 5 are pressed in a direction away from each other with respect to the axial direction. As a result, a contact angle of a rear combination type is imparted to each of the ball bearings 3 and 3, and a preload corresponding to the elasticity of the compression spring 10 is applied to each of the balls 9 and 9 constituting each of the ball bearings 3 and 3. A load is applied. Incidentally, the preload at this time is regulated to such a magnitude that almost no slip occurs at the contact portion between the rolling surface of the balls 9 and 9 and the outer ring and inner ring raceways 4 and 6 during operation. . In the illustrated example, a constant pressure preload method using the elasticity of the compression spring 10 is employed as a preload application method for the ball bearings 3 and 3. However, a fixed position preloading system can be adopted as a preloading system for the rolling bearing that supports the rotating shaft of the spindle.

Such a spindle may be used by rotating the rotary shaft 1 and the ball bearings 3 and 3 at a high speed of about several tens of thousands min ⁻¹ . Therefore, even under such severe use conditions, the outer ring, the inner ring raceways 4 and 6 and the rolling surfaces of the balls 9 and 9 constituting the ball bearings 3 and 3 are damaged early (and further seized). The ball bearings 3 and 3 are generally used with forced lubrication so as not to occur. For this reason, in the illustrated example, during operation, the lubricating oil for lubricating the ball bearings 3, 3 is supplied to the annular members 11, 11 through the oil supply passages 12 provided in the bearing housing 2. Feed into holes 13 and 13. The ball bearings 3 and 3 are lubricated (jet lubrication lubrication) by ejecting the lubricating oil from the nozzle holes 13 and 13 toward the outer peripheral surfaces of the inner rings 7 and 7, respectively. The lubricating oil used to lubricate the ball bearings 3 and 3 in this manner is discharged from the discharge port 14 provided in the bearing housing 2 and then fed into the oil supply passage 12 again.

  In the case of the structure shown in FIG. 4 described above, a pair of ball bearings 3 and 3 are used as rolling bearings that support the rotating shaft 1. However, a double row rolling bearing can be used as the rolling bearing. FIG. 5 shows a structure using a double-row rolling bearing as the rolling bearing. A double-row ball bearing 15 for rotatably supporting the rotary shaft 1 inside the bearing housing 2 includes an outer ring 5a having double-row outer ring raceways 4 and 4 on the inner peripheral surface, and a single row on each outer peripheral surface. A pair of inner rings 7, 7 having an inner ring raceway 6 and a plurality of inner ring raceways 6, 6 and the outer ring raceways 4, 4 are respectively held while being held by cages 8, 8. It consists of balls 9 and 9 that are freely movable.

  In such a double row ball bearing 15, the outer ring 5a is fitted in the bearing housing 2 and the inner rings 7, 7 are fitted in the intermediate portion of the rotary shaft 1. In this state, The end faces of the inner rings 7, 7 are butted against each other. Then, in a state where the end faces of the inner rings 7 and 7 are in contact with each other in this manner, the balls 9 and 9 are provided with predetermined (rolling surfaces of the balls 9 and 9 and the outer rings and the inner ring tracks 4 and 6. The size of each part is regulated so that a preload (fixed position preload) load is applied so that almost no slip occurs at the contact part. Further, during operation, lubricating oil for lubricating the double-row ball bearing 15 is supplied through the oil supply passage 12 provided in the bearing housing 2 and the nozzle holes 13 and 13 provided in the outer ring 5a. , 7 are ejected toward the vicinity of the inner ring raceways 6, 6. Thus, the double row ball bearing 15 is lubricated (jet oil lubrication). The lubricating oil used for lubrication in this way is discharged from the discharge port 14 and then fed into the oil supply passage 12 again.

  By the way, in the case of each spindle as described above, if the rotary shaft 1 can be efficiently rotated, the operation efficiency of the apparatus can be increased accordingly. Therefore, it is desired to realize a reduction in torque (reduction in rotational resistance) of the ball bearing 3 (15) that supports the rotary shaft 1 so that the rotary shaft 1 can be efficiently rotated. In this case, as a method for reducing the torque of a rolling bearing used under forced lubrication like the ball bearing 3 (15), conventionally, drag (each rolling element is removed from the surrounding lubricating oil during the operation of the rolling bearing). There is known a method of reducing the resistance). As specific methods for reducing the drag in this way, there are a method of using a low-viscosity lubricant as described above, and a method of reducing the amount of lubricant supplied to the rolling element installation section. However, when the drag is reduced in this way, the contact is formed between the rolling surfaces of the balls 9 and 9 constituting the ball bearing 3 (15) and the outer and inner ring raceways 4 and 6 correspondingly. The oil film becomes thinner. As a result, if the oil film breaks easily at these contact portions, the rolling surfaces of the balls 9, 9 and the outer ring and inner ring tracks 4, 6 are likely to be damaged early. For this reason, in such a method of reducing the drag, it is difficult to sufficiently reduce the torque of the ball bearing 3 (15) because it is necessary to secure a minimum oil film at each contact portion.

As described above, conventionally, the magnitude of the preload applied to the ball bearing 3 (15) is set so that the rolling surfaces of the balls 9, 9 constituting the ball bearing 3 (15), the outer ring, the inner ring, The contact area with the tracks 4 and 6 was increased to such a degree that slip hardly occurred. The reason for this is that if slipping easily occurs at each of these contact parts, oil film breakage easily occurs at each of these contact parts, and as a result, the rolling surfaces of the balls 9, 9 and the outer ring and inner ring tracks 4 respectively. This is because it was thought that damage was likely to occur at an early stage. Therefore, conventionally, as a method of reducing the torque of the ball bearing 3 (15), a method of reducing the preload load to such an extent that a large slip occurs at the rolling contact portion has not been adopted.
As prior art documents related to the present invention, there are the following Patent Documents 1 and 2 and Non-Patent Document 1.

JP 2002-54451 A Japanese Patent No. 2794336 Seiho Yamamoto, Shigeru Ishihara, “Abrasion in Rolling Bearings—Skidding Damage in High-Speed Bearings”, Lubrication, Japan Lubrication Society, 1979, Vol. 24, No. 11, p. 725-728

  In view of the circumstances as described above, the rotation support device of the present invention can sufficiently reduce the torque of the ball bearing, and at the contact portion between the rolling surface of each rolling element constituting each ball bearing and each track. It was invented to realize a structure that can hardly cause oil film breakage.

The rotation support device of the present invention includes a housing, a rotation shaft, and a ball bearing that rotatably supports the rotation shaft inside the housing.
Among these, the ball bearing has an outer ring raceway on an inner peripheral surface, an outer ring fitted in the housing, an inner ring raceway on an outer peripheral surface, an outer ring fitted on the rotary shaft, the outer ring raceway, and the above A plurality of balls provided so as to be able to roll while being held by a cage between the inner ring raceway and the inner ring raceway.
An axial preload is applied to the ball bearing, and lubricating oil is supplied from the outside of the ball bearing to the ball installation portion (for example, forced lubrication such as oil jet lubrication or oil bath lubrication). The inner ring is rotated at a high speed together with the rotating shaft.
In particular, in the rotation support device of the present invention, it is realized at the time of use by regulating the magnitude of the preload, the type (viscosity) of the lubricating oil, and the supply conditions (how to supply and supply amount). In at least a part of the rotational speed range of the inner ring (for example, on the high speed side), the rotational speed of the cage is substantially constant or the rotational speed of the inner ring is increased regardless of changes in the rotational speed of the inner ring. Accordingly, the rotational speed of the cage is reduced. At the same time, the rolling surface of each ball and the outer ring and the inner ring track are prevented from being damaged or seized in at least a part of the rotational speed range at least during a desired operation time.

  When the rotary support device of the present invention as described above is implemented, the magnitude of the preload load, the type of the lubricating oil, and the supply conditions are each determined by performing an experiment using a target ball bearing in advance. Can be regulated on the street. Hereinafter, this point will be described with reference to FIG.

FIG. 1 is a graph showing the relationship between the ball revolution slip ratio λ (horizontal axis) relative to the inner ring, the traction T acting on the contact portion between the inner ring and the ball, and the ball drag D (vertical axis). . The revolution slip ratio λ can be expressed by the following equation (1).
λ = (V _A −V _B ) / V _A ――――― (1)
V _A : Revolution speed of ball assuming that no slip occurs between inner ring and ball (theoretical value)
V _B : Actual ball revolution speed (actual value: theoretical value or less)

In FIG. 1, T ₁ and T ₂ represent traction curves for contact portions having different normal forces acting on the respective portions. The traction T acting on the contact portion is expressed by “traction coefficient” × “normal force acting on the contact portion”. Here, the “normal force acting on the contact portion” increases as the preload load of the ball bearing increases (decreases as the preload load of the ball bearing decreases). For this reason, if the preload load of the ball bearing is increased, the position of each point of the traction curve can be increased as a whole (for example, the traction curve can be changed from T _{2 to} T ₁ ). Conversely, if the preload of the ball bearing is reduced, the position of each point of the traction curve can be lowered as a whole (for example, the traction curve can be changed from T _{1 to} T ₂ ).

In FIG. 1, D ₁ , D ₂ , and D ₃ represent drag curves for ball bearings having different set lubrication conditions. The reason why each of these drag curves D ₁ , D ₂ , D ₃ becomes a downward-sloping curve in FIG. 1 is as follows. That is, the drag D of the ball is a resistance that the ball receives from the lubricating oil during driving, and decreases as the ball revolution speed decreases (increases as the ball revolution speed increases). On the other hand, the revolution speed of the ball decreases as the revolution slip ratio λ increases, assuming that the rotation speed of the inner ring is constant. For this reason, the ball drag D decreases as the revolution slip ratio λ increases. Accordingly, the drag curves D ₁ , D ₂ , and D ₃ are curved downwards in FIG. The ball drag D varies depending on the lubrication conditions. Specifically, when the viscosity of the lubricating oil is increased or the supply amount of the lubricating oil is increased, the ball drag increases. Conversely, when the viscosity of the lubricating oil is reduced or the supply amount of the lubricating oil is reduced, the ball drag D is reduced. For this reason, if the viscosity of the lubricating oil is increased or the supply amount of the lubricating oil is increased, the position of each point of the drag curve can be increased as a whole (for example, the drag curve is changed from D ₂ → D ₁ → D ₃ can be changed). Conversely, if the viscosity of the lubricating oil is reduced or the supply amount of the lubricating oil is reduced, the position of each point of the drag curve can be lowered as a whole (for example, the drag curve is changed from D ₃ → D ₁ → D ₂ can be changed).

Further, as described above, the ball drag D increases as the ball revolution speed increases (smaller as the ball revolution speed decreases). On the other hand, the revolution speed of the ball increases as the rotational speed of the inner ring increases (the rotational speed of the inner ring decreases) when the revolution slip ratio λ is constant. For this reason, if the rotation speed of the inner ring is increased, the position of each point of the drag curve can be increased as a whole (for example, the drag curve can be changed from D ₂ → D ₁ → D ₃ ). On the other hand, if the rotational speed of the inner ring is reduced, the position of each point on the drag curve can be lowered as a whole (for example, the drag curve can be changed from D ₃ → D ₁ → D ₂ ).

In the graph of FIG. 1 as described above, it is assumed that the operating point is the intersection P between the traction curve T ₁ and the drag curve D ₁ . This intersection point P exists on the traction curve T ₁ in a region X where the change in the traction T increases when the revolution slip rate λ changes. The conventional low torque realization method mentioned above intends to realize low torque by reducing the drag D of the ball by reducing the viscosity of the lubricating oil or reducing the supply amount of the lubricating oil. Is. As shown in FIG. 1, by reducing the drag D of the ball as described above, the drag curve is moved from D ₁ to D ₂ (D ₁ → D ₂ ). This means that the intersection point P is shifted to the intersection point Q between the traction curve T ₁ and the drag curve D ₂ (P → Q). In this case, the difference in drag D or traction T corresponding to these intersections P and Q corresponds to the decrease in torque. However, as described above, when the torque is reduced in this way, it is difficult to secure an oil film at the contact portion between the ball and the inner ring.

On the other hand, the present invention is intended to reduce the torque by reducing the preload. As shown in FIG. 1, by reducing the preload, the traction curve is moved from T ₁ to T ₂ (T ₁ → T ₂ ), so that the position of the operating point is changed from the intersection point P to the traction. It means moving to the intersection R of the curve T ₂ and the drag curve D ₁ (P → R). In this case, the difference in drag D or traction T corresponding to these intersections P and R corresponds to the torque reduction.

  In this case, slipping is likely to occur at the contact portion between the inner ring and the ball by the difference in the revolution slip rate λ corresponding to the intersections P and R. However, even when slippage is likely to occur at the contact portion between the inner ring and the ball as described above, the sliding speed of the contact portion is smaller than a certain value due to the lubrication condition of the contact portion, and It has been conventionally known that if the oil film is not cut at the contact portion, the ball rolling surface and the raceway are not damaged (see Non-Patent Document 1). Therefore, by restricting the lubrication conditions, if the oil film is not cut at the contact portion over the entire rotation speed range of the inner ring that is realized during use, the rolling surface and raceway of the ball may be damaged. Can be prevented.

That is, when it becomes difficult to secure a sufficient oil film at the contact portion between the ball and the inner ring as a result of moving the operating point from the intersection point P to the intersection point R (P → R) as described above, In order to ensure a sufficient oil film at the contact portion, for example, by increasing the supply amount of lubricating oil to lower the bearing temperature, or by using a highly viscous lubricant, the drag curve can be changed to D _By moving from ₁ to D ₃ (D ₁ → D ₃ ), the operating point can be moved from the intersection R to the intersection S (R → S). Here, these intersections R and S exist on the traction curve T ₂ in a region Y {gross slip (GROSS SLIP) region} where the traction T becomes substantially constant even when the revolution slip rate λ changes. For this reason, even when the intersection point R is moved to the intersection point S as described above, the drag D and the traction T hardly change, and as a result, the torque hardly changes. Even if the torque increases in this case (in the example shown in the figure), the amount of increase in torque decreases the preload as described above (the operating point is moved from the intersection point P to the intersection point R). This is much smaller than the torque reduction due to Therefore, in order to secure an oil film at the contact portion as described above, even if the supply amount of lubricating oil is increased, or even if this lubricating oil has a high viscosity, the preload is reduced (the operating point is reduced). The effect of lowering the torque due to the movement from the intersection point P to the intersection point R can be sufficiently maintained.

  In order to realize such low torque, ball bearings are used so that the operating point is in the gross slip region on the traction curve in at least a part of the rotational speed range of the inner ring that is realized during use. It is necessary to regulate (reduce) the magnitude of the preload applied to the. At the same time, in the above-mentioned at least part of the rotational speed range, the lubricating oil is used so that the rolling surface of each ball and each race of the outer ring and the inner ring raceway are not damaged or seized. Type (viscosity) and supply conditions (supply method, supply amount) must be regulated. Therefore, in the following, how to regulate these will be described in detail.

First, how much the preload should be reduced, that is, when an appropriate preload is set, the operating point is a gross slip on the traction curve in at least a part of the rotational speed range of the inner ring that is realized during use. In order to determine whether or not to be arranged in the region, it is only necessary to change the drag D and check whether or not the revolution speed of the ball (= the rotational speed of the cage) changes. The reason for this is that in the case of lubrication conditions using a large amount of lubricating oil such as forced lubrication or oil bath lubrication, the drag D is not the rotational speed of the inner ring, but the revolution speed of the ball (= the rotational speed of the cage). This is because it can be viewed as a function. That is, as described above, when the drag D is changed depending on the rotation speed of the inner ring, the drag curve is D ₂ → D ₁ → D ₃ (the operation point is U → R as the rotation speed of the inner ring is increased). → S) changes. However, since the drag D is a function of the revolution speed of the ball (= the rotational speed of the cage) as described above, for example, in FIG. 1, each exists in the gloss slip region (region Y), and the drag D is mutually At the intersection R and the intersection S that are substantially equal, the revolution speed of the ball (= the rotational speed of the cage) is also equal to each other. Therefore, a ball bearing operation test is performed with an appropriate preload applied, and the ball revolution speed (= cage rotation speed) is almost constant in at least part of the rotation speed range of the inner ring realized during use. If so, it can be determined that the operating point is located in the gross slip region on the traction curve within the rotational speed range.

  In addition, when the operation test of the ball bearing was actually performed, when the operating point is arranged in the gross slip region on the traction curve, the ball revolution speed (= the rotational speed of the cage) is almost as described above. In addition to being constant, it has been found that the revolution speed of the ball (= the rotational speed of the cage) may decrease as the rotational speed of the inner ring increases (see the experimental results described later, see FIG. 3). Therefore, a ball bearing operation test is performed with an appropriate preload applied, and at least part of the inner ring rotation speed range that is realized during use, the ball revolution speed (= cage) as the inner ring rotation speed increases. In the case where the rotational speed is reduced, it can be determined that the operating point is located in the gross slip region on the traction curve within the rotational speed range.

  In addition, an operation test of the ball bearing as described above is performed, and the rolling surface and outer ring of each ball are operated at least during a desired operation time in the rotational speed range where the operating point is arranged in the gloss slip region on the traction curve. If the inner ring raceways are not damaged or seized, the type (viscosity) and supply conditions (supply method, supply amount) of the lubricating oil set at that time can be employed when the present invention is carried out.

  In the case of the rotation support device of the present invention configured as described above, slippage occurs at the contact portion between the rolling surface of each ball and the outer ring and each race of the inner ring over the entire rotation speed range of the inner ring realized at the time of use. A sufficiently low torque can be achieved as compared with the conventional structure in which the preload is set so large that it hardly occurs. Moreover, it is possible to prevent damage and seizure from occurring at each of the contact portions at least during a desired operation time.

  When carrying out the rotation support device of the present invention, for example, as described in claim 2, the number of ball bearings is plural, {a plurality of ball bearings are provided between the outer peripheral surface of the rotary shaft and the inner peripheral surface of the housing. Adopting a configuration in which individual ball bearings are arranged in a state of being combined with each other (giving constant position preload or constant pressure preload)}, and the ball bearing that should regulate the size of the preload load, the type of lubricant and the supply conditions The ball bearings may be at least one of the above ball bearings.

Moreover, when implementing the rotation support apparatus of this invention, Preferably each ball is made from ceramics or a nitride material.
If such a configuration is adopted, at least the rolling contact surface of each ball can be sufficiently secured, and the seizure resistance of the contact portion between the rolling surface of each ball and the outer ring and each race of the inner ring can be secured. Can be secured sufficiently. Therefore, in some cases, the rolling surface and each track are damaged at least during the desired operation time without using a high-viscosity lubricant or increasing the amount of lubricant supplied. And seizure can be prevented.

Moreover, when implementing the rotation support apparatus of this invention, Preferably, the coating process for galling and nitriding are performed to at least one surface of the rolling surface of each ball | bowl, and an inner ring track.
By adopting such a configuration, it is possible to sufficiently secure seizure resistance of at least a contact portion between the rolling surface of each ball and the inner ring raceway. In some cases, even if a high-viscosity lubricating oil is used, or the lubricating oil supply amount is not increased, the rolling surface and each track are provided at least for the desired operation time. Damage and seizure can be prevented.

Experiments conducted to confirm the effects of the present invention will be described with reference to FIGS. In this experiment, an angular ball bearing 3a as shown in FIG. 2 was used as a sample. The basic structure of the ball bearing 3a is substantially the same as that of the ball bearing 3 constituting the rotation support device shown in FIG. 4 described above. ) And redundant description is omitted. The specifications of the ball bearing 3a are as follows.
Outer diameter D _o : 83mm
Inner diameter D _i : 45 mm
Width W _{o of} outer ring 5: 19 mm
Inner ring 7a width W _i : 25 mm
Diameter of ball 9 d: 11.112 mm
Total number n of balls 9: 14 Contact angle α: 20 °

In this experiment, the ball bearing 3a was operated under the following test conditions (same conditions as in use).
Rotational speed (inner ring rotation): 0 to 32000min ^-1
Radial load: 265N
Preload load (thrust load): Select one value from the range of 0 to 816N Lubrication method: Forced lubrication (jet lubrication lubrication)
Lubricating oil: # 90 Turbine oil Lubricating oil amount: 2.6 liter / min
Lubrication temperature: 70 ° C

Then, by operating the ball bearing 3a under such test conditions, how much preload is applied to the ball bearing 3a, the rotational speed range of the inner ring 7a realized during use ( 0 to 32000 min ⁻¹ ) or whether the operating point exists in the gross slip region on the traction curve (gross slip between the rolling surfaces of the balls 9 and 9 and the inner ring raceway 6) To see if this occurs. For this purpose, specifically, the rotation speed of the inner ring 7a and the rotation speed of the cage 8 (each of the above balls) for the ball bearing 3a to which each preload (588N, 392N, 294N, 0N) is applied. 9 and 9), and the relationship between the two was investigated. FIG. 3 shows the measurement results. In FIG. 3, a straight line (broken line) Z indicates data (theoretical value) when no slip occurs between the rolling surfaces of the balls 9 and 9 and the inner ring raceway 6.

As shown in the measurement results of FIG. 3, in the case of a ball bearing 3a with a preload of 588 N, the cage is maintained over the entire rotational speed range (0 to 32000 min ⁻¹ ) of the inner ring 7a realized during use. The rotational speed of 8 and the rotational speed of the inner ring 7a tended to be proportional. From these results, in the case of the ball bearing 3a with a preload of 588 N, the rotation speed of each of the balls 9 and 9 is changed over the entire rotational speed range (0 to 32000 min ⁻¹ ) of the inner ring 7a realized during use. It was found that no gross slip occurred between the moving surface and the inner ring raceway 6. In other words, it has been found that the preload load of 588 N is within the preload setting range that has been conventionally employed.

On the other hand, in the case of each ball bearing 3a in which the preload is set to 392N, 294N, 0N {1.5 times (397.5N) or less of the radial load (265N)}, the inner ring 7a realized at the time of use. Within a range of rotation speeds (0 to 32000 min ^-1 ), a certain rotation speed (about 27500 min ^-1 when the preload is 392 N, about 20000 min ^-1 when the preload is 392 N, and ⁰ N when the preload is 0 N In a range of 10500 min ^-1 or less in this case, the rotational speed of the cage 8 and the rotational speed of the inner ring 7a tended to be in a proportional relationship (as viewed roughly). However, in a range where the rotational speed of the inner ring 7a exceeds the certain rotational speed, the rotational speed of the cage 8 decreases as the rotational speed of the inner ring 7a increases or the inner ring 7a It showed a tendency to become almost constant regardless of changes in the rotation speed. The reason why such a tendency appears is that, as described above, in the range where the rotational speed of the inner ring 7a exceeds the certain rotational speed, the rolling surfaces of the balls 9, 9 and the inner ring raceway 6 This is because a gross slip occurred between them. That is, from such a result, if the magnitude of the preload applied to the ball bearing 3a is 1.5 times or less of the radial load, the rotational speed range of the inner ring 7a realized during use (0 to 32000 min) ^-1 ) (a range exceeding the certain rotational speed), it was found that gross slip could be generated between the rolling surfaces of the balls 9, 9 and the inner ring raceway 6.

In this experiment, the rotational speed of the inner ring 7a is 32000 min ⁻¹ (gross slip is generated) for each ball bearing 3a with a preload of 392N, 294N, 0N (1.5 times or less of the radial load). The rolling operation of each of the balls 9 and 9 constituting each of the ball bearings 3a is performed continuously for 5 minutes (desired operation time) in a state where the rotation speed range is the maximum speed in this experiment). It was examined whether the surface, outer ring, and inner ring raceways 4 and 6 were damaged or seized. The desired operation time is determined depending on the application, but the rolling surfaces and outer rings of the balls 9, 9 and the races of the inner ring 4, 6 constituting the rotation support device for supporting the high-speed rotation shaft. As the time for evaluating whether damage or seizure occurs, the operation time in this test was 5 minutes. And in this experiment, as a result of performing such an evaluation, even if each said ball bearing 3a is each drive | operated for 5 minutes, the rolling surface of each said ball | bowl 9, 9 and an outer ring | wheel, each inner ring | wheel each track | truck 4, It was confirmed that no damage or seizure occurred in 6.

  Therefore, in the case of the ball bearing 3a shown in FIG. 2, when the operation is performed under the operating conditions (test conditions) as described above, the preload load is 1.5 times or less of the radial load. Torque reduction of the ball bearing 3a can be sufficiently achieved, and a sufficient oil film is secured at the contact portion between the rolling surface of each ball 9, 9 and the outer ring, each raceway 4, 6 of the inner ring, It was found that the durability could be secured sufficiently. From the measurement results shown in FIG. 3, when the present invention is carried out, the rotation speed range of the inner ring 7a realized at the time of use is substantially the entire rotation speed range in which gross slip occurs (particularly on the high speed side). ), Gross slip rate {GS rate. Regarding the rotation speed of the cage 8, the value represented by “(theoretical value−actual value) / theoretical value” is 80% or less {preferably 25 to 80% (more preferably 35 to 80%)}. It is preferable to set the magnitude of the preload and the lubrication conditions.

Diagram showing the traction curve (T _1, T ₂₎ and the drag curve _{(D 1, D 2, D} 3). Sectional drawing which shows the ball bearing used in the experiment conducted in order to confirm the effect of this invention. The diagram which shows the result of the same experiment. Sectional drawing which shows the 1st example of the conventionally known rotation support apparatus. Sectional drawing which shows the 2nd example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Bearing housing 3, 3a Ball bearing 4 Outer ring raceway 5, 5a Outer ring 6 Inner ring raceway 7, 7a Inner ring 8 Cage 9 Ball 10 Compression spring 11 Annular member 12 Oil supply passage 13 Nozzle hole 14 Discharge port 15 Double row ball bearing

Claims (2)

  The housing includes a housing, a rotating shaft, and a ball bearing that rotatably supports the rotating shaft inside the housing. The ball bearing includes an outer ring raceway on an inner peripheral surface, and is fitted in the housing. A plurality of outer rings, an inner ring raceway on the outer peripheral surface, a plurality of inner rings that are fitted on the rotating shaft, and a roll that is held between the outer ring raceway and the inner ring raceway by a cage. The ball bearing is provided with a preload in the axial direction to the ball bearing, and while supplying lubricating oil from the outside of the ball bearing to the ball installation portion, the inner ring is moved together with the rotating shaft. In a rotary support device that is rotated at a high speed, by restricting the magnitude of the preload and the type and supply conditions of the lubricating oil, at least a part of the rotational speed range of the inner ring realized at the time of use is achieved. The rotation speed of this inner ring Regardless of the rotation, the rotational speed of the cage is substantially constant or the rotational speed of the inner ring is increased so that the rotational speed of the cage decreases, and in the at least part of the rotational speed range, A rotation support device characterized in that the rolling surface of each ball and each outer race and each race of inner race are prevented from being damaged during at least a desired operation time.   2. The ball bearing according to claim 1, wherein the number of ball bearings is plural, and the ball bearing that should regulate the size of the preload and the type and supply condition of the lubricating oil is at least one of the ball bearings. The described rotary support device.

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