JP5371230B2 - Alternator bearing - Google Patents

Description

  The present invention relates to a grease filling amount of a bearing, and particularly to a grease filling amount of a bearing for an alternator that supports a rotating shaft of the alternator.

  A conventional automotive alternator includes a casing, a rotating shaft rotatably supported on the casing by a bearing, a stator fixed to the casing, a rotor fixed to the rotating shaft at a position facing the stator, and a rotating shaft. And a pulley to be fixed. Then, the rotation of the engine is transmitted to the rotating shaft by the endless belt stretched around the pulley.

  Further, a bearing that rotatably supports a rotating shaft is described in Japanese Patent Laid-Open No. 2003-13976 (Patent Document 1). The bearing described in the publication includes an inner ring 102, an outer ring 103, a plurality of rolling elements 104 disposed between the inner ring 102 and the outer ring 103, and a cage 105 that holds an interval between adjacent rolling elements 104. The rolling bearing 101 includes an annular seal 106 that seals the inside of the bearing. For the lubrication of the rolling bearing 101, grease is mainly used.

The sealing seal 106 includes a fixed portion 106a fixed to the outer ring 103 on the outer peripheral portion, a contact lip portion 106b and a non-contact lip 106c on the inner peripheral portion facing the inner ring 102, and a space between the outer peripheral portion and the inner peripheral portion. A cored bar 106d that holds the shape of the hermetic seal 106; The contact lip portion 106b is in contact with the inner ring 102. On the other hand, the non-contact lip portion 106c does not come into contact with the inner ring 102, and prevents foreign matters from entering due to the labyrinth effect. Thus, it is described that an increase in contact torque between the inner ring 102 and the sealing seal 106 and a decrease in sealing performance can be prevented.
Japanese Patent Laid-Open No. 2003-13976

  The hermetic seal 106 configured as described above is deformed by heat generated by the rotation of the rolling bearing 101. Specifically, when the rolling bearing 101 rotates at high speed, the temperature inside the bearing becomes higher than the temperature outside the bearing. Accordingly, the pressure inside the bearing becomes higher than the pressure outside the bearing.

  Here, the portion of the hermetic seal 106 where the cored bar 106d is disposed can maintain the shape against the pressure difference. On the other hand, the periphery of the lip portions 106b and 106c made of only resin is greatly deformed to the outside of the rolling bearing 101 (in the direction of arrow a in FIG. 5). As a result, a gap is generated between the contact lip portion 106b and the inner ring 102 and grease leaks to the outside of the bearing, and the tip of the non-contact lip portion 106c may come into contact with the inner ring 102 to increase the contact torque.

  On the other hand, when the pressure outside the bearing becomes higher than the pressure inside the bearing, the periphery of the lip portions 106b and 106c is deformed inside the rolling bearing 101 (in the direction of arrow b in FIG. 5). As a result, the contact torque between the contact lip portion 106b and the inner ring 102 increases, and the gap between the non-contact lip portion 106c and the inner ring 102 increases, which may reduce the labyrinth effect.

  Grease leaking to the outside of the bearing may cause slippage between the pulley and the endless belt or cause malfunction of the electronic component. On the other hand, an increase in contact torque not only inhibits the smooth rotation of the rotating shaft, but also causes wear of the hermetic seal 106. The wear of the hermetic seal 106 causes contamination of grease by wear powder and a decrease in sealing performance.

  Accordingly, an object of the present invention is to provide a bearing for an alternator, which supports a rotating shaft of the alternator and prevents deterioration in sealing performance due to an external factor such as a temperature difference or a pressure difference.

  The alternator bearing according to the present invention rotatably supports the rotating shaft of the alternator. Specifically, an inner ring having circumferential grooves at both axial ends of the outer diameter surface, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and a gap between the inner ring and the outer ring are sealed. An annular sealing member. The sealing member includes a fixed portion fixed to the outer ring on the outer peripheral portion, a contact lip portion that contacts the side wall of the circumferential groove on the inner peripheral portion, and a wall surface facing the axially inner side of the bearing from the wall surface of the circumferential groove. A bearing for an alternator including a protrusion protruding toward the surface.

  In the alternator bearing configured as described above, even when the pressure outside the bearing becomes higher than the pressure inside the bearing, the protrusion prevents the increase in contact torque generated between the contact lip portion and the circumferential groove. In addition, by providing the protrusion, it is possible to set in advance a tightening allowance between the contact lip portion and the circumferential groove. As a result, even when the pressure inside the bearing becomes higher than the pressure outside the bearing, it is possible to prevent a gap from being generated between the contact lip and the circumferential groove, and to effectively prevent grease leakage. it can.

  Preferably, the tip of the protrusion is a convex curved surface. Thereby, the contact surface pressure between the circumferential groove and the protrusion can always be made uniform. As a result, a stable contact state can be formed and the contact torque can be stabilized.

  Preferably, the protrusions are arranged at equal intervals at a plurality of locations on the circumference of the sealing member. By arranging the plurality of protrusions at equal intervals, the surface pressure applied to each protrusion can be made uniform. As a result, the contact torque is stabilized, contributing to stable rotation of the bearing.

  Preferably, the sealing member includes an elastic body that constitutes the fixed portion and the contact lip portion, and a shape holding member that is disposed between the fixed portion and the contact lip portion and holds the shape of the elastic body. The elastic body is formed of either one of hydrogenated nitrile rubber and ester-resistant acrylic rubber. Hydrogenated nitrile rubber and ester-resistant acrylic rubber are superior in heat resistance and chemical resistance as compared with nitrile rubber, acrylic rubber and the like generally used as a sealing member. As a result, stable properties can be maintained and the sealing performance at high temperatures can be improved.

  Preferably, the elastic body further includes a first non-contact lip portion that branches from the position immediately below the inner diameter side end portion of the shape maintaining member to the inner side in the axial direction of the bearing and is provided with a predetermined gap from the inner ring. As described above, by disposing the first non-contact lip portion in the vicinity of the shape holding member with little shape change, the gap between the first non-contact lip portion and the inner ring can be kept constant. As a result, stable sealing performance can be exhibited without being affected by changes in temperature and pressure.

  Preferably, the elastic body has a waist portion having a relatively small thickness in an inner peripheral region thereof, and a second non-contact lip extending from the waist portion to the outside in the axial direction of the bearing and provided with a predetermined gap from the inner ring. And a section. The second non-contact lip portion functions as a dust lip that effectively prevents dust from entering the bearing. Here, since the contact torque is made uniform by the protrusions, the deformation of the waist is also stabilized. As a result, the gap between the second non-contact lip portion and the inner ring is constant, and a stable labyrinth effect can be obtained. In the present specification, the “inner peripheral region of the elastic body” refers to a portion radially inward of the shape maintaining member.

  According to the present invention, it is possible to obtain an alternator bearing that prevents a decrease in the sealing performance of the contact lip portion and an increase in contact torque by providing a protrusion on the sealing member.

  With reference to FIGS. 1-4, the alternator 11 for vehicles which concerns on one Embodiment of this invention, and the front bearing 21 and the rear bearing 31 as a rolling bearing employ | adopted as the alternator 11 for vehicles are demonstrated. 1 is a sectional view of a front bearing 21 employed in the alternator 11, FIG. 2 is a diagram showing a sealing seal 26 employed in the front bearing 21, and FIG. 3 is a diagram showing a rear bearing 31 employed in the alternator 11. 4 is a cross-sectional view of the alternator 11 for an automobile.

  First, referring to FIG. 4, an automotive alternator 11 includes, as main components, a casing 12, a rotating shaft 13, a pulley 14, a stator 15, a rotor 16, and a front bearing 21 as an alternator bearing. And a rear bearing 31.

  The casing 12 is configured by bolting a front bracket 12a and a rear bracket 12b. And the rotating shaft 13, the stator 15, the rotor 16, the front bearing 21, the rear bearing 31, etc. are accommodated.

  The rotating shaft 13 is rotatably supported on the casing 12 by a front bearing 21 and a rear bearing 31. Further, it is inserted through the pulley 14 outside the casing 12 and through the rotor 16 and the slip ring 17 inside the casing 12. A brush 18 is pressed against the slip ring 17 by a spring 19.

  An endless belt (not shown) is attached to the pulley 14 and rotates the rotating shaft 13 as the engine (not shown) rotates. Moreover, in this embodiment, it functions also as a fan which cools the alternator 11 for motor vehicles.

  The stator 15 is a ring-shaped member and is fixed to the casing 12. On the other hand, the rotor 16 is fitted and fixed to the rotary shaft 13 and rotates integrally with the rotary shaft 13. The stator 15 and the rotor 16 are arranged so as to face each other, and a predetermined gap is provided between them. A coil is wound around the stator 15 and the rotor 16.

  The automotive alternator 11 having the above configuration converts engine rotation into electricity. Specifically, the rotating shaft 13 and the rotor 16 rotate integrally with the rotation of the engine. At this time. Electricity is generated between the stator 15 and the rotor 16 by the principle of electromagnetic induction. The electricity generated by the automobile alternator 11 is charged in a battery (not shown) and used for the operation of each electrical component.

  Next, referring to FIG. 1, the front bearing 21 includes an inner ring 22, an outer ring 23, a plurality of balls 24 as rolling elements disposed between the inner ring 22 and the outer ring 23, and a distance between adjacent balls 24. It is a deep groove ball bearing provided with the cage | basket 25 which hold | maintains, and the sealing seal 26 as a sealing member which seals both ends. Further, in order to maintain the smooth rotation of the ball 24, the inside of the bearing is filled with grease as a lubricant.

  The inner ring 22 has a raceway surface 22a that receives the ball 24 at the axial center portion of the outer diameter surface thereof, and a circumferential groove 22b that receives the sealing seal 26 at both axial ends. Similarly, the outer ring 23 has a raceway surface 23a at the axial center of the inner diameter surface, and circumferential grooves 23b at both axial ends.

  Next, referring to FIG. 1 and FIG. 2, the sealing seal 26 is an annular member disposed at both axial ends of the inner ring 22 and the outer ring 23, and is an elastic body formed of a resin material. Sealing member 26a, and a cored bar 26b as a shape holding member formed of a metal material. The seal member 26a includes a fixed portion 26c fixed to the outer ring 23, a waist portion 26d, a contact lip portion 26e that contacts the inner ring 22, and first and second non-contacts arranged with a predetermined gap from the inner ring 22. Contact lip portions 26f and 26g, and protrusions 26h (hereinafter referred to as “surface pressure adjusting protrusions”) are provided.

  For example, the seal member 26a is formed of one of hydrogenated nitrile rubber and ester-resistant acrylic rubber. Hydrogenated nitrile rubber is superior in heat resistance and has no problem in chemical resistance as compared with nitrile rubber generally used as a sealing member. Further, the ester-acrylic rubber is excellent in heat resistance as compared with the nitrile rubber like the hydrogenated nitrile rubber. Moreover, compared with acrylic rubber, it is excellent in chemical resistance against chemicals such as ester oil and compressor oil. As a result, stable properties can be maintained and the sealing performance at high temperatures can be improved.

  The cored bar 26b is disposed between the fixed part 26c and the contact lip part 26e and functions as a shape holding member that holds the shape of the seal member 26a having low rigidity. The fixing portion 26c is formed on the outer peripheral portion of the hermetic seal 26, and is fitted and fixed to the circumferential groove 23b of the outer ring 23 as a non-rotating side race.

  The waist portion 26d is a portion having a relatively small thickness provided in the inner peripheral region of the seal member 26a. The waist portion 26d includes a contact lip portion 26e and a surface pressure adjusting projection 26h that extend inward in the axial direction of the bearing toward the side wall of the circumferential groove 22b, and a second portion that extends toward the opposite side (outward in the axial direction of the bearing). Two non-contact lip portions 26g are arranged.

  The contact lip portion 26e is in contact with the side wall of the circumferential groove 22b of the inner ring 22 as the rotation side raceway ring, and prevents leakage of grease to the outside of the bearing and intrusion of dust to the inside of the bearing. In FIG. 1, in order to clarify the shape of the contact lip portion 26 e, the tip of the contact lip portion 26 e is drawn so as to enter the inner ring 22. Contact the surface.

  The first non-contact lip portion 26f branches off directly from the inner diameter side end of the cored bar 26b to the inside in the axial direction of the bearing. In addition, a predetermined gap is provided between the first non-contact lip portion 26 f and the inner ring 22. Thereby, leakage of grease to the outside of the bearing can be prevented by the labyrinth effect, and an increase in contact torque can be prevented.

  The second non-contact lip portion 26g extends from the waist portion 26d to the outside in the axial direction of the bearing. In addition, a predetermined gap is provided between the second contact lip portion 26 g and the inner ring 22. As a result, it is possible to prevent dust from entering the bearing due to the labyrinth effect.

  The surface pressure adjusting protrusion 26h protrudes from the wall surface on one side of the sealing seal 26 toward the side wall of the circumferential groove 22b. Further, the tip of the surface pressure adjusting projection 26h (referring to the “surface facing the side wall of the groove 22b”) is a convex curved surface. Further, the surface pressure adjusting protrusions 26h are formed at least at one place in the circumferential direction of the seal seal 26, and are desirably provided at a plurality of places on the circumference at equal intervals. Specifically, it can be provided at four locations at intervals of 90 °.

  When the hermetic seal 26 is incorporated in the front bearing 21, the surface pressure adjusting projection 26h is disposed so as to face the side wall of the circumferential groove 22b with which the contact lip portion 26e abuts. The surface pressure adjusting projection 26h contacts the side wall of the circumferential groove 22b when the seal seal 26 is deformed inward in the axial direction of the bearing (in the direction of arrow A in FIG. 1), and the contact lip portion 26e and the circular It functions as an adsorption release mechanism that prevents an increase in contact surface pressure generated between the circumferential groove 22b and the circumferential groove 22b.

  At this time, the contact surface pressure between the circumferential groove 22b and the surface pressure adjusting protrusion 26h is always kept uniform by making the tip of the surface pressure adjusting protrusion 26h contacting the side wall of the circumferential groove 22b a convex curved surface. can do. As a result, a stable contact state can be formed and the contact torque can be stabilized.

  Further, by arranging the plurality of surface pressure adjustment protrusions 26h at equal intervals, the surface pressure applied to each surface pressure adjustment protrusion 26h can be made uniform. As a result, the contact torque is stabilized, contributing to stable rotation of the bearing.

  On the other hand, when the hermetic seal 26 is deformed to the outside in the axial direction of the bearing (in the direction of arrow B in FIG. 1), the surface pressure adjusting projection 26h is separated from the circumferential groove 22b to prevent an increase in contact torque. At this time, the tightening margin of the contact lip portion 26e is set larger than the conventional one so that no gap is generated between the contact lip portion 26e and the circumferential groove 22b.

  Specifically, the general tightening allowance of the conventional rolling bearing 101 as shown in FIG. 5 is 0.100 ± 0.148 mm, but according to one embodiment of the present invention shown in FIG. The tightening allowance δ of the front bearing 21 is set to 0.250 ± 0.148 mm. That is, even if design tolerance is taken into consideration, the tightening margin is always set to a positive value.

  Here, when the tightening margin is increased, an increase in contact torque between the contact lip portion 26e and the circumferential groove 22b becomes a problem. However, according to the present invention, it is possible to prevent the contact torque from exceeding a certain value by providing the surface pressure adjusting projection 26h.

  According to the hermetic seal 26 having the above-described configuration, the contact lip portion 26e can maintain stable sealing performance without being affected by deformation caused by changes in temperature and pressure. Further, since the contact torque is made uniform by the surface pressure adjusting projection 26h, the deformation of the waist portion 26d is stabilized. As a result, the gap between the second non-contact lip portion 26g and the inner ring 22 is constant, and a stable labyrinth effect can be obtained.

  Furthermore, by disposing the first non-contact lip portion 26f directly below the core bar 26b with little deformation, the amount of deformation associated with changes in temperature and pressure can be reduced. As a result, the gap between the first non-contact lip portion 26f and the inner ring 22 can always be kept constant, so that a stable labyrinth effect can be obtained.

  Next, the rear bearing 31 that supports the rotating shaft 13 of the alternator 11 will be described with reference to FIG. The basic configuration of the rear bearing 31 is the same as that of the front bearing 21 shown in FIG. 1, so that the description of the common points is omitted and the differences will be mainly described.

  The rear bearing 31 includes an inner ring 32 having a raceway surface 32a and a circumferential groove 32b, an outer ring 33 having a raceway surface 33a and a circumferential groove 33b, a plurality of balls 34 as rolling elements, and an interval between adjacent balls 34. It is a deep groove ball bearing provided with a retainer 35 to be retained and a sealing seal 36 as a sealing member for sealing a gap between the inner ring 32 and the outer ring 33.

  The basic shape of the hermetic seal 36 is the same as that of the hermetic seal 26 shown in FIGS. 1 and 2, and includes a seal member 36a formed of a resin material and a cored bar 36b formed of a metal material. An annular member. Further, the seal member 36a includes a fixing portion 36c, a waist portion 36d, a contact lip portion 36e, first and second non-contact lip portions 36f and 36g, and a surface pressure adjusting projection 36h. Further, the tightening allowance between the contact lip portion 36e and the circumferential groove 32b is set to 0.250 ± 0.149 mm.

  As in the case of the front bearing 21, the rear bearing 31 having the above configuration can maintain high sealing performance without being affected by changes in temperature and pressure.

  Next, a test for confirming the effect of the present invention will be described with reference to Table 1. First, as the bearing used for the test, three front bearings 21 shown in FIG. 1 and three rear bearings 31 shown in FIG. 3 were prepared. These bearings were stepwise increased to 4000 rpm, 8000 rpm, 12000 rpm, and 16000 rpm to confirm the presence or absence of grease leakage. Grease leakage was confirmed visually and by changes in bearing weight. Further, the weight of the front bearing 21 before the start of the test was 200 gf, and the weight of the rear bearing 31 before the start of the test was 115 gf. The results are shown in Table 1.

  Referring to Table 1, no grease leakage was visually observed in all the bearings tested. Moreover, it was confirmed that the change in weight before and after the start of the test was also a small change that was negligible at 0.01 gf to 0.04 gf. Thereby, it was confirmed that this invention can prevent the leakage of grease effectively.

  As described above, when the sealing seals 26 and 36 according to the present invention are employed, the alternator bearings 21 and 31 excellent in lubricity can be obtained by effectively preventing leakage of grease and mixing of dust.

  In the above embodiment, the surface pressure adjusting protrusions 26h and 36h are integrally formed as a part of the seal members 26a and 36a. However, the present invention is not limited to this, and the seal member is manufactured as a separate part. You may attach to 26a, 36a. In this case, the surface pressure adjusting protrusions 26h and 36h may be made of a material different from that of the seal members 26a and 36a, and are preferably manufactured from a material having excellent wear resistance.

  Moreover, in said embodiment, as grease with which the front bearing 21 and the rear bearing 31 are enclosed, the combination of base oil and a thickener of arbitrary compositions can be employ | adopted, and various additives are used as needed. Can be added. However, since the automotive alternator 11 is very hot, it is desirable that the grease has excellent high temperature characteristics.

  Furthermore, in the above embodiment, an example in which a deep groove ball bearing is adopted as a bearing for supporting the rotating shaft 13 has been shown. However, the present invention is not limited to this, and an angular ball bearing, a four-point contact ball bearing, a cylindrical roller bearing, and a tapered roller Regardless of whether the rolling element is a ball or a roller, such as a bearing, a self-aligning roller bearing, and a needle roller bearing, it can be applied to any rolling bearing.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention is advantageously used for alternator bearings.

It is sectional drawing of the front bearing which concerns on one Embodiment of this invention. It is an expanded sectional view of the seal seal employ | adopted as the alternator bearing of FIG. It is sectional drawing of the rear bearing which concerns on one Embodiment of this invention. It is sectional drawing of the alternator for motor vehicles. It is sectional drawing of the conventional bearing for alternators.

Explanation of symbols

  11 Automotive alternator, 12 Casing, 12a Front bracket, 12b Rear bracket, 13 Rotating shaft, 14 Pulley, 15 Stator, 16 Rotor, 15a, 16a Coil, 17 Slip ring, 18 Brush, 19 Spring, 21 Front bearing, 31 Rear Bearing, 22, 32 Inner ring, 22a, 23a, 32a, 33a Raceway surface, 22b, 23b, 32b, 33b Circumferential groove, 23, 33 Outer ring, 24, 34 Ball, 25, 35 Cage, 26, 36 Seal seal, 26a, 36a Seal member, 26b, 36b Core metal, 26c, 36c Fixed part, 26d, 36d Lumbar part, 26e, 36e Contact lip part, 26f, 26g, 36f, 36g Non-contact lip part, 26h, 36h Surface pressure adjusting projection, 101 Rolling bearing, 102 Inner ring, 103 Wheels, 104 rolling element 105 retainer, 106 hermetic seal, 106a fixed portion, 106b contact lip, 106c contactless lip, 106d metal core.

Claims (4)

An alternator bearing that rotatably supports the rotating shaft of the alternator,
An inner ring having circumferential grooves at both axial ends of the outer diameter surface;
Outer ring,
A plurality of rolling elements disposed between the inner ring and the outer ring;
An annular sealing member for sealing a gap between the inner ring and the outer ring,
The sealing member is
A fixed portion fixed to the outer ring on the outer periphery;
A contact lip portion that abuts against the side wall of the circumferential groove on the inner periphery,
A protrusion protruding toward the side wall of the circumferential groove from the wall surface facing the axial inner side of the bearing, and the tip of the protrusion is a convex curved surface,
The protrusions are arranged at equal intervals at a plurality of locations on the circumference of the sealing member,
Preventing an increase in contact surface pressure when the contact surface pressure varies between the contact lip portion and the side wall of the circumferential groove due to variations in temperature and pressure;
Alternator bearing. The sealing member is
An elastic body constituting the fixed portion and the contact lip portion;
A shape holding member that is disposed between the fixed portion and the contact lip portion and holds the shape of the elastic body;
The alternator bearing according to claim 1, wherein the elastic body is formed of one of hydrogenated nitrile rubber and ester-resistant acrylic rubber.   The elastic body further includes a first non-contact lip portion that branches off from an inner diameter side end portion of the shape maintaining member to an inner side in an axial direction of the bearing and is disposed with a predetermined gap from the inner ring. Item 3. The alternator bearing according to Item 2.   The elastic body includes a waist portion having a relatively small thickness in an inner peripheral region thereof, and a second non-contact lip extending from the waist portion to the outside in the axial direction of the bearing and provided with a predetermined gap from the inner ring. The alternator bearing according to claim 2, further comprising a portion.

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