JP2007247711A - Rolling bearing for underwater rotary device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive rolling bearing for an underwater rotary device which can maintain rotational accuracy constant for a long period of time, by preventing occurrence of creep between a bearing ring and a housing. <P>SOLUTION: A plurality of rolling bearings 10, 12 are used for an underwater rotary device having a housing 8 housing a rotational shaft 6 to which an impeller for circulating water is attached, so as to rotatably support the rotational shaft. Each rolling bearing comprises: bearing rings (inner and outer rings 14, 16) rotatable relatively to each other and opposed to each other is disposed between the rotational shaft and the housing; and a plurality of rolling elements 18 incorporated between the bearing rings to be capable of rolling. In at least one of rolling bearings out of these bearings, one bearing ring is fixed to the housing by interference fit, the other bearing ring is fixed to the rotational shaft by clearance fit, and elastic material 36 is disposed in a gap G between the inner ring 14 (inner ring inner diameter face 14s) and the rotational shaft 6 (rotational shaft outer diameter face 6s). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling bearing that supports a rotating shaft to which an impeller is attached in an underwater rotating device such as a submersible pump or a stirring device.

  Conventionally, as this type of submersible rotating device, various submersible pumps used in a submerged state in, for example, sewage treatment plants and water purification plants are known (see Patent Document 1). As an example, the submersible pump shown in FIG. 2 includes a pump casing 2 having a water suction port 2a and a discharge port 2b, in which an impeller 4 for circulating water is rotatably disposed, A housing 8 is disposed on the casing 2 in a vertical shape and accommodates a rotating shaft 6 to which the impeller 4 is attached.

  The housing 8 includes a motor chamber 8 a in which a motor (electric motor) that controls the rotating shaft 6 is accommodated, and an oil chamber 8 b provided in the housing 8 between the motor chamber 8 a and the pump casing 2. Has been. In this case, the rotating shaft 6 extends in the pump casing 2 along the vertical direction from the motor chamber 8a through the oil chamber 8b, and the impeller 4 is attached to the extending end. In the configuration example shown in the figure, the rotating shaft 6 is rotatably supported by a plurality of rolling bearings 10 and 12 respectively disposed on the upper and lower sides of the motor chamber 8a.

  As the rolling bearings 10 and 12, for example, as shown in FIG. 3A, the inner ring 14 fixed to the rotary shaft 6, the outer ring 16 fixed to the housing 8, and the inner and outer rings can be freely rolled. A ball bearing including a plurality of incorporated rolling elements (balls) 18 and a cage 20 that rotatably holds the rolling elements (balls) one by one is applied. In the configuration example of FIG. 3A, the rolling bearings 10 and 12 are provided with a sealing plate 22 for sealing the inside of the bearing, and the sealing plate 22 has a base end (outer diameter portion). 22 a is fixed to the outer ring 16, and a tip end (inner diameter part) 22 b extends toward the inner ring 14 and is positioned in a non-contact state with respect to the inner ring 14. The sealing plate 22 may be a contact or non-contact type seal instead of such a shield.

  As shown in FIG. 2, the motor (electric motor) housed in the motor chamber 8 a is fixed to the housing 8 so as to face the rotor 24 (for example, a permanent magnet) fixed to the rotating shaft 6 and the rotor 24. And a stator (for example, an electromagnet) 26. On the other hand, in the oil chamber 8b, a mechanical seal 28 for sealing the motor chamber 8a in a liquid-tight state is fixed to the rotary shaft 6, and in order to improve the wear resistance and lubricity of the mechanical seal 28, etc. A fixed amount of lubricant (for example, mineral oil-based lubricant) 30 is enclosed.

  In such a submersible pump, when a motor (electric motor) is driven to pass a current through a coil (not shown) of a stator (electromagnet) 26, the framing is caused by the magnetic interaction between the electromagnet 26 and the rotor (permanent magnet) 24. The rotational force can be applied to the rotating shaft 6 through the permanent magnet 24 in accordance with the left hand rule. At this time, after the impeller 4 attached to the rotary shaft 6 rotates together with the rotary shaft 6, the water W1 sucked from the water suction port 2a moves along the pump casing 2 (W2), and then the discharge port. It is discharged from 2b (W3).

  Incidentally, since the submersible pump as described above is used in a submerged state, heat generated from, for example, the motor (electric motor) and the rolling bearings 10 and 12 during the pump operation is likely to be trapped in the housing 8. In this case, the rotary shaft 6 is thermally expanded depending on the amount of heat in the housing 8, and the internal load of the rolling bearings 10 and 12 is increased according to the amount of thermal expansion. As a result, the rotational accuracy of the rolling bearings 10 and 12 is increased. It may be difficult to maintain (for example, rotational stability) constant over a long period of time.

  As a measure for solving this problem, for example, as shown in FIG. 3A, a configuration is proposed in which one of the rolling bearings 10 and 12 is fixed to the housing 8 by “clearance fitting”. In this configuration, the inner ring inner surface 14s of the inner ring 14 of any one of the rolling bearings 10 (12) is fixed to the rotating shaft outer diameter surface 6s of the rotating shaft 6 by “fitting fit”, while the outer ring 16 A gap G is interposed between the outer ring outer diameter surface 16 s and the housing inner diameter surface 8 s of the housing 8. For this reason, even when the rotary shaft 6 is thermally expanded, the rolling bearings 10 and 12 (outer ring 16) slide in the axial direction or the radial direction along the gap G in accordance with the amount of thermal expansion. It is possible to prevent the internal load of (12) from increasing. The other rolling bearing 12 (10) is fixed to the housing 8 by “fitting fit” in order to stably support the impeller 4 and the rotating shaft 6.

  In this case, the impeller 4 directly receives the water pressure (load) of the flowing water in the pump casing 2. For example, if the flowing amount and the flowing direction of the flowing water are not constant, the impeller 4 acts on the impeller 4. The water pressure (load) to be changed may change. At this time, since the water pressure (load) acting on the impeller 4 is transmitted to the rotating shaft 6 as it is, an unstable swaying load corresponding to a change in the water pressure (load) is generated on the rotating shaft 6. Will do. Further, the swinging load generated on the rotating shaft 6 is attached in a state where the impeller 4 is unbalanced with respect to the rotating shaft 6 (for example, the impeller 4 is not symmetrical with respect to the rotation center). It also occurs when

  Depending on the magnitude of such a swinging load, for example, a low-speed slip called creep may occur between the outer ring outer surface 16s and the housing inner surface 8s shown in FIG. Here, the generation of creep will be explained. As shown in FIG. 3A, for example, the run-out load acting on the rotary shaft 6 is caused by the inner ring 14 and the rolling elements of the rolling bearing 10 (12). It is transmitted to the outer ring 16 via each (ball) 18. At this time, due to the gap G interposed between the outer ring outer diameter surface 16s and the housing inner diameter surface 8s, the outer ring 16 is displaced in the direction of the housing inner diameter surface 8s. In this state, the rotating shaft 6 rotates while pressing the outer ring 16 against the housing inner diameter surface 8s, so that the outer ring 16 slides and rotates so as to roll along the housing inner diameter surface 8s. As a result, creep occurs between the outer ring outer surface 16s and the housing inner surface 8s.

  When creep occurs, sliding contact between the outer ring outer diameter surface 16s and the housing inner diameter surface 8s is repeated. As a result, for example, the outer ring outer diameter surface 16s and the housing inner diameter surface 8s may be worn. At this time, depending on the amount of wear, it may be difficult to firmly fix the rolling bearing 10 (12) to the housing 8, and the rolling bearing 10 (12) may be rattled. Then, the rotating shaft 6 cannot be stably supported by the rolling bearing 10 (12). As a result, the rotating shaft 6 is deviated (eccentric), and the rotor 24 of the motor (electric motor) is thereby also decentered. In some cases, the stator 26 may be shaken (eccentric). And if a pump is drive | operated in this state, it will become impossible to rotate the rotating shaft 6 smoothly and stably.

  As a measure for preventing the occurrence of such creep, for example, as shown in FIG. 3B, a rubber O-ring that is continuous along the circumferential direction between the outer ring outer diameter surface 16s and the housing inner diameter surface 8s. A configuration in which 32 is interposed has been proposed. However, in such a configuration, a configuration for interposing the O-ring 32 (for example, the O-ring housing groove 34) must be constructed in the outer ring outer diameter surface 16s, and a construction cost for that is required separately. The manufacturing cost of the bearing will increase.

Although the rolling bearings 10 and 12 as described above have been described on the assumption that the inner ring rotates, creep may occur between the inner ring and the housing even in the outer ring rotating bearing. Therefore, it is possible to keep the rotational accuracy constant over a long period of time by preventing the occurrence of creep between one of the bearing rings and the housing of the inner ring rotation and the outer ring rotation. Although development of a low-cost rolling bearing for an underwater rotating device is desired, such technology is not known at present.
JP 2001-140908 A

  The present invention has been made in order to meet such a demand, and an object of the present invention is to prevent the occurrence of creep between the race and the housing, thereby maintaining the rotational accuracy constant over a long period of time. It is an object of the present invention to provide a possible low-cost rolling bearing for an underwater rotating device.

  In order to achieve such an object, the present invention is used in an underwater rotating device in which a rotating shaft to which an impeller for circulating water is attached is accommodated in a housing, and a plurality of rolling members that rotatably support the rotating shaft. Each rolling bearing is provided between a rotating shaft and a housing, and is provided with a bearing ring disposed so as to be relatively rotatable with each other, and a plurality of rolling elements that are rotatably incorporated between the bearing rings. In at least one of the plurality of rolling bearings, one of the bearing rings is fixed to the housing by an interference fit, and the other bearing ring is a clearance fit to the rotating shaft. The elastic material is interposed between the other raceway ring and the rotating shaft.

  In this case, in an atmosphere in which the inside of the housing has risen to a predetermined temperature, at least one rolling bearing maintains a fixed state by an interference fit between one of the bearing rings and the housing, and the other bearing ring and the rotating shaft are in contact with each other. Maintain a fixed state by clearance fit. Further, at least the surface of the elastic material is coated with a lubricant, thereby preventing wear between the race and the rotating shaft.

  According to the present invention, it is possible to realize a low-cost rolling bearing for an underwater rotating device capable of maintaining the rotational accuracy constant over a long period of time by preventing the occurrence of creep between the race and the housing. be able to.

  Hereinafter, a rolling bearing for an underwater rotating device according to an embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, the same components as those in the underwater rotating device (FIG. 2) and the rolling bearing (FIG. 3) described above are denoted by the same reference numerals in the drawing, and the description thereof is omitted.

  As shown in FIG. 1A, the rolling bearings 10 and 12 of the present embodiment are provided between the rotary shaft 6 and the housing 8, and at least one of the plurality of rolling bearings 10 and 12 is provided. In one rolling bearing (for example, the upper rolling bearing 10 in FIG. 2), one bearing ring (for example, the outer ring 16) is fixed to the housing 8 by “fitting fit”, and the other bearing ring (for example, the inner ring). 14) is fixed to the rotary shaft 6 by “clearance fit”. In the remaining rolling bearing 12 (the lower rolling bearing in FIG. 2), both race rings (inner and outer rings 14, 16) are provided with the rotating shaft 6 and the rotating shaft 6 in order to firmly support the impeller 4 and the rotating shaft 6. It is fixed to the housing 8 by “fitting fit”.

  In this case, in the upper rolling bearing 10, the outer ring outer diameter surface 16s of the outer ring (one raceway ring) 16 and the housing inner diameter surface 8s of the housing 8 are fitted in close contact with each other without any gap. On the other hand, a gap G is interposed between the inner ring inner surface 14 s of the inner ring (the other race ring) 14 and the rotating shaft outer surface 6 s of the rotating shaft 6. For this reason, even when the rotating shaft 6 is thermally expanded by the amount of heat generated in the housing 8 during the pump operation, the inner ring 14 slides in the axial direction or the radial direction along the gap G according to the amount of thermal expansion. It is possible to prevent the internal load of the rolling bearing 10 from increasing. As a result, it becomes possible to maintain the rotational accuracy (for example, rotational stability) of the rolling bearing 10 constant over a long period of time.

  Further, during the operation of the pump, the water pressure (load) acting on the impeller 4 is changed by the flowing water in the pump casing 2 (FIG. 2). Are transmitted to the outer ring 16 via the inner ring 14 and the rolling elements (balls) 18 respectively. In this case, the inner ring 14 is fixed to the rotation shaft 6 by “clearance fitting”, and a gap G is interposed between the inner ring inner surface 14s and the rotation shaft outer surface 6s.

  Thereby, the inner ring 14 rotates together with the rotating shaft 6 in a state where the same portion of the inner ring inner diameter surface 14s is always in contact with the rotating shaft outer diameter surface 6s. In another way of understanding, the rotating shaft 6 rotates together with the inner ring 14 while maintaining a state where it is always in pressure contact with the same portion of the inner ring inner surface 14s. In this state, the whirling load acts as a static load, for example, in the radial direction from the rotating shaft 6 to the inner ring 14, so that a low speed called creep is formed between the inner ring inner surface 14s and the rotating shaft outer surface 6s. There is no slip.

  By the way, the swinging load of the rotating shaft 6 may act as a component force not only in the radial direction of the rotating shaft 6 but also in the axial direction. At this time, when the inner ring 14 reciprocates (finely moves) along the axial direction, minute wear may occur between the inner ring inner surface 14s and the rotary shaft outer surface 6s. In this case, depending on the magnitude and the degree of wear, there is a possibility that adhesion wear may occur.

  Therefore, as shown in FIGS. 1A and 1B, for example, two elastic members 36 are provided in the gap G between the inner ring 14 (inner ring inner diameter surface 14s) and the rotating shaft 6 (rotating shaft outer diameter surface 6s). Intervened. Here, as each elastic member 36, for example, a rubber O-ring having a circular cross section continuous in the circumferential direction along the gap G is assumed. In this case, each elastic material (O-ring) 36 is accommodated and held in two annular grooves 38 formed by digging the inner ring inner surface 14 by a predetermined amount along the circumferential direction. The diameter and surface shape of the elastic material (O-ring) 36, or the distance and position between the elastic materials (O-ring) 36 in the gap G are, for example, the usage environment, shape and size of the bearing, or the rotation axis Since it is arbitrarily set according to the size of 6 swings (swing amount), there is no particular limitation here.

  As described above, the elastic material (O-ring) 36 is interposed in the gap G, so that the swinging load of the rotating shaft 6 is absorbed and weakened by the elastic material 36 and then acts on the inner ring 14. That is, since the elastic material (O-ring) 36 functions as a cushioning material, the swinging load from the rotating shaft 6 to the inner ring 14 does not act directly. In this case, an extremely slight load action acts between the rotating wheel 6 (rotating shaft outer diameter surface 6s) and the inner ring 14 (inner ring inner diameter surface 14s). Thereby, the frictional resistance between the rotating shaft outer diameter surface 6s and the inner ring inner diameter surface 14s is reduced, and as a result, wear of the rotation shaft outer diameter surface 6s and the inner ring inner diameter surface 14s can be reduced.

  In order to enhance such effects, it is preferable to apply the lubricant 40 to at least the surface of the elastic material (O-ring) 36. As a result, the frictional resistance between the outer surface 6s of the rotating shaft and the inner surface 14s of the inner ring can be further reduced, so that the wear of the outer surface 6s of the rotating shaft and the inner surface 14s of the inner ring can be prevented. In addition, as the lubricant 40, for example, commercially available grease, oil, or the like may be applied.

  Further, as described above, the swinging load generated on the rotating shaft 6 is transmitted from the rotating shaft 6 to the outer ring 16 via the inner ring 14 and the rolling elements (balls) 18. In this case, the run-out load transmitted to the outer ring 16 is a rotation that continuously presses the outer ring outer diameter surface 16s along the housing inner diameter surface 8s of the housing 8 in the circumferential direction every time the rotating shaft 6 makes one rotation. A load is applied to the outer ring 16. However, the outer ring 16 has an outer ring outer diameter surface 16s closely and closely fitted to the housing inner diameter surface 8s without any gap, so that creep occurs between the outer ring outer diameter surface 16s and the housing inner diameter surface 8s. The low-speed slip called is not generated.

  Further, the state where the creep does not occur as described above is maintained even in an atmosphere in which the inside of the housing 8 (FIG. 2) is raised to a predetermined temperature during the pump operation. At this time, in the rolling bearing 10, one of the race rings (outer ring 16) and the housing 8 maintain a fixed state by “fitting fit”, and the other race ring (inner ring 14) and the rotary shaft 6 are “clearance”. The fixed state by “fitting” is maintained. Note that the predetermined temperature is not particularly limited because it changes in accordance with the type and size of the underwater rotating device to which the rolling bearing 10 is applied.

  As described above, according to the present embodiment, the outer ring 16 of the rolling bearing 10 is fixed to the housing 8 by “tight fit”, the inner ring 14 is fixed to the rotating shaft 6 by “clearance fit”, and By interposing an elastic material (O-ring) 36 and a lubricant 40 in a gap G between the inner ring 14 (inner ring inner diameter surface 14s) and the rotation shaft 6 (rotation shaft outer diameter surface 6s), the inner ring inner diameter surface 14s and the rotation shaft are provided. It is possible to eliminate wear between the outer diameter surface 6s and between the outer ring outer diameter surface 16s and the housing inner diameter surface 8s, thereby reliably preventing the occurrence of creep and wear caused by minute vibrations, so-called fretting wear. can do. In this case, since the rotation accuracy (for example, rotation stability) of the rolling bearing 10 can be maintained constant over a long period of time, the rotating shaft 6 can be stably and firmly supported by the rolling bearing 10. . As a result, it is possible to keep the underwater rotating device operating stably over a long period of time. Furthermore, according to the present embodiment, it is possible to provide a rolling bearing that is lower in cost than conventional ones.

In the embodiment described above, in the upper rolling bearing 10 of FIG. 2, one race ring (for example, the outer ring 16) is fixed to the housing 8 by “fitting fit”, and the other race ring (for example, The inner ring 14) is fixed to the rotary shaft 6 by “clearance fitting”. However, the present invention is not limited to this, and the same configuration may be applied to all the rolling bearings 10 and 12.
In the above-described embodiment, the two rolling bearings 10 and 12 are illustrated in the drawings. However, the present invention is not limited to this, and the present invention is also applied to an underwater rotating device using three or more rolling bearings. By applying the technique, it is possible to achieve the same effect as the above-described embodiment.

  In the above-described embodiment, the configuration in which the two elastic members 36 are interposed in the gap G is illustrated. However, the present invention is not limited to this, and three or more elastic members 36 are interposed in the gap G. You may comprise. Furthermore, although the case where the lubricant 40 is applied to the surface of the elastic material 36 is assumed in the above-described embodiment, the present invention is not limited to this, and the lubricant 40 is applied over the entire gap G. You may make it do.

  In the above-described embodiment, the elastic material 36 is accommodated in the annular groove 38 formed in the inner ring 14 (inner ring inner diameter surface 14). As a modified example, as shown in FIG. In the gap G between the inner ring inner surface 14s and the rotating shaft 6 (rotating shaft outer surface 6s), a predetermined amount of the outer shaft outer surface 6s is dug in the circumferential direction to form an annular groove 38. Alternatively, the elastic member 36 may be accommodated.

  Furthermore, in the above-described embodiment, no particular mention was made of a method of continuously making the elastic material 36 along the gap G in the circumferential direction. However, the elastic material 36 is made straight (straight) continuously along the circumferential direction. Alternatively, meandering may be performed across the circumferential direction. Further, the elastic material 36 may be provided intermittently instead of being continuous along the circumferential direction. In this case, the directions of the interrupted elastic members 36 may be arranged in parallel along the circumferential direction, or may be arranged obliquely so as to cross the circumferential direction. Further, the material of the elastic member 36 is not limited to rubber, and instead of this, for example, resin may be applied.

  Furthermore, in the above-described embodiment, the explanation has been made assuming the inner ring rotation, but the technique of the present invention can also be applied to a bearing for outer ring rotation. That is, in at least one of the rolling bearings 10 and 12, the inner ring 14 is fixed to the housing 8 by “fitting fit” and the outer ring 16 is fixed to the rotating shaft 6 by “clearance fitting”. It is a case. In this case, the elastic material 36 may be interposed in the gap between the outer ring outer diameter surface 16 s of the outer ring 16 and the rotation shaft outer diameter surface 6 s of the rotation shaft 6.

(a) is sectional drawing which shows the structure of the rolling bearing for submersible rotating apparatuses which concerns on one embodiment of this invention, (b) expands the structure around the clearance gap between the inner ring | wheel and rotating shaft of the figure (a). FIG. 6C is a cross-sectional view showing a configuration of a rolling bearing for an underwater rotating device according to a modification of the present invention. Sectional drawing which shows schematically the whole structure of an underwater rotation apparatus. (a) is sectional drawing which shows the structure of the conventional rolling bearing for submersible rotating apparatuses, (b) is sectional drawing which illustrated the bearing structure in which the conventional measure for preventing generation | occurrence | production of creep was taken.

Explanation of symbols

6 Rotating shaft 6s Rotating shaft outer diameter surface 8 Housing
10,12 Rolling bearing 14 Inner ring 14s Inner ring inner diameter surface 16 Outer ring 18 Rolling element 36 Elastic material G Gap

Claims (3)

A plurality of rolling bearings used in a submersible rotating device in which a rotating shaft to which an impeller for circulating water is attached is housed in a housing, and rotatably supporting the rotating shaft;
Each rolling bearing is provided between a rotating shaft and a housing, and includes a bearing ring arranged to face each other so as to be relatively rotatable, and a plurality of rolling elements incorporated so as to be able to roll between the bearing rings.
In at least one of the plurality of rolling bearings, one of the bearing rings is fixed to the housing by an interference fit, and the other bearing ring is fixed to the rotating shaft by a clearance fit. And
A rolling bearing for an underwater rotating device, wherein an elastic material is interposed between the other race ring and the rotating shaft.   In an atmosphere in which the inside of the housing has risen to a predetermined temperature, at least one rolling bearing maintains a fixed state in which one race ring and the housing are fixed by an interference fit, and the other race ring and the rotation shaft are a clearance fit. The rolling bearing for an underwater rotating device according to claim 1, wherein a fixed state is maintained. The rolling bearing for an underwater rotating device according to claim 1 or 2, wherein a lubricant is applied to at least the surface of the elastic material.

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