JP5189453B2 - Rolling bearing with pulley and resin pulley - Google Patents

Description

  The present invention relates to a rolling bearing with a resin pulley in which a resin pulley member is integrally formed by injection molding of resin on an outer diameter portion of an outer ring of a pulley and a rolling bearing that guides a timing belt for driving a cam of an automobile engine.

  The pulley is used to guide a timing belt for driving a cam of an automobile engine, an auxiliary belt for driving an auxiliary machine such as an alternator, and the like. This pulley is formed between an inner diameter cylindrical portion 3 fixed to the outer ring 2 of the rolling bearing 1, an outer diameter cylindrical portion 5 having a belt guide surface 4, and inner and outer cylindrical portions 3, 5 as shown in FIG. It has a disk part 6 and a plurality of ribs 7 formed radially on the disk part 6. The disc portion 6 is reinforced by the ribs 7 to ensure the strength when the load by the belt is applied to the outer diameter cylindrical portion 5.

  This pulley is generally made of a resin, and the molding is performed using a mold 9 having a cavity 8 for integrally molding each part of the pulley as shown in FIG. A plurality of gate holes 10 for injecting molten resin into the cavity are formed in the mold 9, and the resin is injected through the gate holes 10. The injected resin is cooled in the cavity 8 and contracts in volume. This volume shrinkage rate is larger as the temperature drop of the resin is higher.

  That is, in the cavity 8, where the resin has reached a high temperature, it is cooled from the high temperature state to room temperature, so that the volumetric shrinkage is large, whereas in the location where the resin has reached after being cooled to a low temperature, Since it is cooled from the low temperature state to room temperature, the volume shrinkage is small.

When the volume contraction rate varies in the cavity 8 as described above, the roundness of the outer diameter cylindrical portion 5 is reduced as shown in FIG. 5 (see reference numeral 5a in FIG. 5), and the pulley rotates. The smoothness of the is impaired. In view of this, as disclosed in Patent Documents 1 and 2, inventions have been disclosed in which the position of the gate hole 10 through which molten resin is injected into the cavity 8 is devised to reduce the variation in volume shrinkage.
JP-A-4-34260 JP 2008-149502 A

  In the method shown in Patent Document 1, gate holes 10 are formed at circumferentially symmetrical positions (intermediate positions) between adjacent ribs 7 and 7, and molten resin is uniformly injected from each gate hole 10. This gate hole 10 is formed between all the ribs 7, and the resin flowing in from each gate hole 10 flows in all directions of the outer diameter cylindrical part 5, the inner diameter cylindrical part 3, and the adjacent ribs 7, 7. Spread evenly. For this reason, the roundness in the outer diameter cylindrical portion 5 is improved.

  In the method shown in Patent Document 2, seven or more gate holes 10 are provided at equal intervals on the circumference of one circle centered on the rotation axis, and the resin is injected from the gate holes 10 in the same manner as described above. Is. The number of gate holes is preferably an odd number. By doing so, the weld part (small shrinkage) and the flow part (large shrinkage) are positioned symmetrically with respect to the rotation axis. Roundness is further improved.

  In the configuration of Patent Document 1 or 2, since the gate holes 10 are provided at a predetermined interval, the outer diameter cylindrical portion 5 is periodically arranged corresponding to the distance between each gate hole 10 and the outer diameter cylindrical portion 5. The outer diameter is likely to vary (corresponding to the distance between the gate holes 10). Since the fluctuation of the outer diameter is slight, it does not affect the rotation of the pulley itself.

  However, this slight variation in the outer diameter may cause periodic sound when the pulley rotates.

  That is, when the outer diameter cylindrical portion 5 is a perfect circle, the pulley rotating at a constant speed emits sound having a constant frequency determined by its shape, material, and the like. On the other hand, when this perfect circle is slightly deviated, sound of a plurality of frequencies slightly deviated simultaneously is emitted corresponding to the deviation (variation in outer diameter). If this shift is periodic, the plurality of sounds interfere with each other, and a new sound (sound) having the same frequency as the shift is generated. This resounding is perceived by the human ear as a periodic change in volume, particularly when the frequency is a low frequency of several Hz. For this reason, this volume change becomes very harsh and often causes a problem in terms of quietness.

  Since this sag is caused by a slight periodic fluctuation of the outer diameter, it can be suppressed by perfecting the roundness of the outer diameter cylindrical portion. However, in order to do so, it is necessary to greatly improve the accuracy of roundness, which is a serious problem in terms of manufacturing cost.

  In view of the above, an object of the present invention is to easily and inexpensively suppress the twist generated when the pulley rotates.

  In order to solve the above-described problems, the present invention suppresses the occurrence of distorting by making it difficult for sound of multiple frequencies to interfere.

  The plurality of acoustic interferences are likely to occur when the outer diameter varies with periodicity. This is due to the fact that multiple acoustic phases tend to overlap due to this periodicity. Therefore, by intentionally shifting the periodicity (rotationally asymmetric), it is possible to eliminate the distortion that occurs as a result of interference between the two sounds.

  By the way, even when the periodicity of the outer diameter is shifted in this way, the roundness basically does not change. This roundness is defined by the difference between the maximum diameter and the minimum diameter of the outer diameter cylindrical portion (see paragraph 0008 of Patent Document 2), and even if the periodicity is shifted, the maximum and minimum diameters are basically unchanged. It is. For this reason, the rotational smoothness of the pulley is not impaired due to the shifting of the periodicity.

  The configuration of the present invention includes an inner diameter cylindrical portion fixed to the outer ring of the rolling bearing, an outer diameter cylindrical portion having a belt guide surface, a disk portion formed between the inner and outer cylinder portions, and a radial shape on the disk portion. In the pulley having a plurality of ribs formed on the outer periphery, the outer diameter of the outer diameter cylindrical portion is rotationally asymmetric with respect to the rotation axis.

  This rotational asymmetry means that the outer diameter of the outer diameter cylindrical portion of the pulley is a 6-fold rotational axis (60-degree rotational symmetry), a 4-fold rotational axis (90-degree rotational symmetry), a 3-fold rotational axis (120-degree rotational symmetry), etc. It means having no specific rotation axis. Thus, by making it rotationally asymmetric, the plurality of sounds emitted from this pulley are less likely to interfere with each other, and the occurrence of sag is suppressed.

  The means for making the outer diameter of the outer diameter cylindrical portion as rotationally asymmetric as in the above configuration can be selected as appropriate, but as one of them, the pulley is formed by pouring and solidifying molten material into a mold. The injection may be performed through a gate hole provided in the mold so as to be rotationally asymmetric with respect to the rotation axis.

  In the outer peripheral portion of the outer diameter cylindrical portion, the closer to the gate hole, the higher the temperature of the resin, so that the degree of contraction is correspondingly large. For this reason, when this gate hole is periodically formed as in Patent Document 1, etc., periodicity is generated in the outer diameter corresponding to the periodicity of the gate hole position. On the other hand, since the resin is injected non-uniformly by providing the gate hole with rotational asymmetry, this rotational asymmetry of the outer diameter is ensured.

Instead of making the gate hole position rotationally asymmetric as described above, the pulley is formed by injecting and solidifying a molten material into a mold, and the injection is provided in the mold. The ribs are formed through a plurality of gate holes having different hole diameters, and the ribs are formed at equal intervals in the circumferential direction .

  Thus, by making the hole diameter non-uniform, the amount of resin injected from each gate hole can be changed. Then, as in the case of the rotationally asymmetric gate position as described above, the resin is injected nonuniformly from each gate hole, and the rotationally asymmetry of the outer diameter cylindrical portion is ensured. Is done.

In this configuration, the hole diameter can be non-uniform and the gate hole position can be rotationally asymmetric.
By doing so, the resin injection becomes more uneven, and the rotational asymmetry of the outer diameter is ensured.

  Furthermore, in each said structure, it is preferable that the thickness of the said rib is not the same with all the ribs.

  A part of the resin injected into the mold passes through the ribs and reaches the entire interior of the mold. At that time, the thicker the rib, the slower the flow rate of the resin flowing in the rib, and the resin is cooled during that time. That is, by changing the thickness of the rib, the outer diameter of the outer diameter cylindrical portion corresponding to the position of the rib becomes non-uniform, and rotational asymmetry of the outer diameter is ensured.

  The pulleys shown in each of the above structures can be appropriately selected as long as they can be molded by injection / solidification using a mold, but are made of resin from the viewpoint of light weight and ease of molding. Is preferred.

  Although the kind of this resin material can also be selected suitably, a nylon-type resin is preferable from a cost side, and a phenol-type resin etc. are preferable from a strength side. This nylon-based resin may be slightly inferior in strength compared with phenol-based resin or the like, but this strength can be sufficiently compensated by providing reinforcing ribs between the inner and outer diameter cylindrical portions.

Furthermore, the pulley described in each of the above-described structures can be integrally formed on the outer ring of the rolling bearing by resin injection molding to provide a rolling bearing with a resin pulley.
For the integration of the bearing and the pulley, it is preferable that the outer ring of the bearing can be incorporated in a mold for molding the pulley, and the outer ring is fixed together with the injection of the resin into the mold. By doing so, the pulley can be molded and the bearing can be integrated at the same time, so the operation is very simple.

  Further, an inner diameter cylindrical portion fixed to the outer ring of the rolling bearing, an outer diameter cylindrical portion having a belt guide surface, a disk portion formed between the inner and outer cylinder portions, and a plurality of radial portions formed on the disk portion. In a pulley molding die that has a cavity for integrally forming a rib and molds a pulley by injecting and solidifying a molten material into the cavity, the outer diameter of the outer cylindrical portion is rotationally asymmetric. The mold can be configured so as to form the cavity.

  By performing resin molding using this mold, a pulley having an outer diameter of the outer diameter cylindrical portion that is rotationally asymmetric can be obtained. However, since the significance of such rotationally asymmetry has been described above, description thereof will be omitted.

  In the mold, the gate hole for injecting the molten material into the cavity can be provided in a rotationally asymmetric manner with respect to the rotating shaft of the pulley to be molded.

  Since the significance of making the gate hole rotationally asymmetric in this way is the same as that of making the gate rotationally asymmetric, the description thereof is also omitted.

  Instead of providing the gate holes rotationally asymmetric as described above, the hole diameters of the gate holes for injecting the molten material into the cavities can be made not uniform in all the gate holes.

  By making the hole diameters of the gate holes non-uniform in this way, the amount of resin injected from each gate hole can be made non-uniform. However, since its significance has also been described above, its description is omitted.

Further, in this mold, the hole diameter of the gate hole can be non-uniform and the position of the gate hole can be rotationally asymmetric.
By doing so, the injection of the resin can be made more non-uniform, but the significance thereof has been described above, and the description thereof will be omitted.

Furthermore, in each said structure, it is preferable that the said cavity is formed so that the thickness of the said rib may not become the same with all the ribs.
Since the significance of making the thickness of the rib non-uniform is also described above, the description thereof is omitted.

  According to the present invention, the outer diameter of the outer diameter cylindrical portion of the pulley is made rotationally asymmetric to lose periodicity, thereby preventing interference of a plurality of sounds generated from the pulley. For this reason, it is possible to prevent the occurrence of warpage due to this interference, and it is possible to ensure quietness when the pulley rotates.

  A pulley-equipped bearing according to the present invention is shown in FIGS. The bearing with pulley is formed between a rolling bearing 1, an inner diameter cylindrical portion 3 fixed to the outer ring 2 of the rolling bearing 1, an outer diameter cylindrical portion 5 having a belt guide surface 4, and inner and outer cylindrical portions 3, 5. The disc portion 6 and a plurality of ribs 7 formed radially on the disc portion 6 are configured.

  As shown in FIG. 4, this pulley-equipped bearing is manufactured using a pulley forming die 9 having a cavity 8 formed in accordance with the shape of the pulley. The mold 9 has six gate holes 10 formed in accordance with the position of the inner diameter cylindrical portion 3 of the pulley, and the molten resin is injected into the cavity 8 from the gate hole 10. The gate hole 10 is formed rotationally asymmetric about the pulley rotation axis, and the hole diameters of the gate holes 10 are different from each other.

  By forming the gate hole 10 to be rotationally asymmetric and changing the hole diameter for each gate hole 10, the timing at which the resin supplied from each gate hole 10 reaches a position corresponding to the outer diameter cylindrical portion 5 in the cavity 8 is reached. It becomes non-uniform. As a result, the degree of shrinkage of the resin in the outer diameter cylindrical portion 5 becomes uneven, and the outer diameter can be made rotationally asymmetric.

  Further, the thickness of the rib 7 is not uniform in all, and a part of the thickness (see 7a in FIG. 1) is formed thicker than the other thickness (see 7b in the same figure). . A part of the resin injected from the gate hole 10 is supplied to the outer diameter cylindrical portion 5 through the rib 7, but by making the thickness of the rib 7 uneven in this way, the outer diameter cylindrical portion 5. The supply speed to the pipe varies depending on the thickness of the rib 7 passing through. Thereby, the rotational asymmetry of the outer diameter of the outer diameter cylindrical portion 5 can be obtained as described above.

  As shown in FIG. 1, resin injection traces (hereinafter simply referred to as “gate 11”) injected from the gate hole 10 remain on the side surface of the inner diameter cylindrical portion 3 of the pulley formed by the mold 9. ing. The gate 11 is rotationally asymmetric about the rotation axis of the pulley and has a different diameter corresponding to the position of the gate hole 10. The gate 11 is not particularly necessary for the function of the pulley, and may be removed by polishing or the like, or may be used as it is.

  1 and 2, in order to obtain the rotational asymmetry of the outer diameter of the outer cylindrical portion 5, (1) the position of the gate hole 10 is rotationally asymmetric. (2) the hole diameter of the gate hole 10 is increased. Although three means of changing for each gate hole 10 and (3) making the thickness of the rib 7 uneven are adopted, at least one of these three may be selected. This is because each of them can exert its effect.

  Alternatively, instead of obtaining rotational asymmetry by each of the above means, the outer diameter cylindrical portion 5 may be subjected to machining such as polishing to obtain this rotational asymmetry.

  In this configuration, the pulley is formed integrally with the outer ring 2 of the rolling bearing. However, for example, the rotating shaft may be directly fitted into the inner diameter cylindrical portion 3 of the pulley. This is because even in this case, the effect of suppressing the twisting of the pulley during rotation can be exhibited.

The side view which shows one Embodiment of the bearing with a pulley which concerns on this invention A perspective view showing the same embodiment Cross-sectional perspective view showing a general bearing with pulley Side sectional view showing molding of bearing with pulley by mold Partial side view showing a typical pulley

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling bearing 2 Outer ring 3 Inner diameter cylindrical part 4 Belt guide surface 5 Outer diameter cylindrical part 6 Disc part 7 Rib 8 Cavity 9 Pulley mold 10 Gate hole 11 Gate

Claims (3)

Formed between an inner diameter cylindrical portion (3) fixed to an outer ring (2) of a rolling bearing (1), an outer diameter cylindrical portion (5) having a belt guide surface (4), and inner and outer cylindrical portions (3, 5). In the pulley having the disc part (6) and a plurality of ribs (7) formed radially on the disc part (6),
The outer diameter of the outer diameter cylindrical portion (5) is rotationally asymmetric with respect to the rotation axis, and the pulley is molded by injecting and solidifying the molten material into the mold (9). The injection is performed through a plurality of gate holes (10) having different hole diameters provided in the mold (9), and the ribs (7) are formed at equal intervals in the circumferential direction. Features pulley.   The pulley according to claim 1, characterized in that the thickness of the ribs (7) is not the same for all ribs (7). A rolling bearing with a resin pulley, wherein the pulley according to claim 1 or 2 is integrally formed by injection molding of resin on an outer ring (2) of the rolling bearing (1).

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