JP2007071319A - Rolling bearing with pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure having excellent resistance to wear and chemical and capable of preventing occurrence of electrolytic corrosion on a contact face with different kind of metal even if a pulley 9b is made of magnesium alloy. <P>SOLUTION: The whole surface of the pulley 9b is covered with a hard carbon film (DLC coating). Since this DLC coating has excellent resistance to wear and chemical, resistance to wear and chemical of the pulley 9b can be improved. The DLC coating is also provided on the contact face with a steel-made outer ring 13 of a bearing in which the pulley 9b is externally fitted to prevent occurrence of electrolytic corrosion on the contact face. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The rolling bearing with pulley according to the present invention applies a desired tension to, for example, a belt or timing belt (hereinafter simply referred to as “belt”) for driving an auxiliary machine of an automobile engine or a camshaft. Use to do.

  In order to give a desired tension to a belt for driving an auxiliary machine of an automobile engine or a camshaft, for example, a tension applying device as shown in FIGS. 3 to 4 is used. The support shaft 3 is loosely engaged with the long hole 2 formed in the base plate 1, and the flange portion of the adjustment bolt 5 supported on the base plate 1 is screwed into the screw hole formed in the head 4 of the support shaft 3. Yes. A rolling bearing 6 with a pulley is externally supported by a flange of the support shaft 3 via a sleeve 7.

  The pulley-equipped rolling bearing 6 includes a rolling bearing 8 that is externally supported by the flange portion of the support shaft 3, and a pulley 9 that is externally fitted and fixed to an outer ring 13 that constitutes the rolling bearing 8. In the illustrated example, a single-row deep groove ball bearing is used as the rolling bearing 8 among them. That is, the rolling bearing 8 includes an inner ring 11 having a deep groove type inner ring raceway 10 on an outer peripheral surface, the outer ring 13 having a deep groove type outer ring raceway 12 on an inner peripheral face, and the inner ring raceway 10 and the outer ring raceway 12. A plurality of balls 14, 14 provided so as to be capable of rolling therebetween. The inner ring 11 is externally supported on the flange portion of the support shaft 3 via the sleeve 7. The pulley 9 is fixedly fitted around the outer ring 13. In the case of the illustrated example, the pulley 9 is formed by subjecting a metal plate such as a mild steel plate to plastic processing such as drawing and forming the whole into an annular shape.

  When a desired tension is applied to the belt by the tension applying device as described above, the base plate 1 is coupled and fixed to a fixing portion such as a cylinder block and the belt is fixed to the front side surface of the pulley 9 (FIG. 3). To the lower surface of -4. Then, by rotating the adjustment bolt 5, the position of the pulley 9 in the axial direction of the adjustment bolt 5 is changed, and the tension applied to the belt by the pulley 9 is adjusted.

  The pulley 9 constituting the rolling bearing 6 with pulley of the tension applying device as shown in FIGS. 3 to 4 is made by plastically deforming a metal plate, so that strength and shape accuracy can be ensured, but weight is increased. . For this reason, conventionally, as described in Patent Document 1, for example, it has been considered to produce a pulley by injection molding of a synthetic resin. FIG. 5 shows the pulley-equipped rolling bearing 6a described in Patent Document 1.

  A pulley 9a constituting the pulley-equipped rolling bearing 6a includes an inner diameter side cylindrical portion 15 and an outer diameter side cylindrical portion 16 provided concentrically with each other. The outer peripheral surface of the intermediate portion of the inner diameter side cylindrical portion 15 and the inner peripheral surface of the intermediate portion of the outer diameter side cylindrical portion 16 are connected by a ring-shaped connecting portion 17. The reinforcing ribs 18 are provided radially. In such a pulley 9 a, the inner diameter side cylindrical portion 15 is fixed around the outer ring 13 constituting the rolling bearing 8 in a state where the outer diameter side portion of the outer ring 13 is molded on the inner diameter side. When the pulley 9a is made by injection molding of synthetic resin in this way, the weight of the pulley-equipped rolling bearing 6a can be reduced.

  However, since the synthetic resin is a material having a low thermal conductivity, when the pulley 9a is made by injection molding of the synthetic resin as described above, the heat generated inside the rolling bearing 8 during operation is generated in the rolling bearing 8. It becomes easy to hit inside. As a result, the grease sealed in the rolling bearing 8 is likely to deteriorate, and the life of the rolling bearing 8 may be shortened. For this reason, a structure in which the pulley is made of a magnesium alloy has been conventionally known, as described in Patent Document 2, for example. Since the magnesium alloy is excellent in heat dissipation, the heat generated inside the rolling bearing during operation can be efficiently released to the outside. Accordingly, heat is less likely to be generated inside the rolling bearing, and the life of the rolling bearing can be extended. Magnesium alloys, like synthetic resins, are lighter than iron-based metals.

However, magnesium alloys have lower wear resistance and chemical resistance than iron-based metals. The pulley described above is used by being incorporated in a belt or timing belt tensioning device for driving an auxiliary machine of an automobile engine or a camshaft. Therefore, if the wear resistance is low, wear due to rubbing with the belt stretched over the pulley increases. Further, in the case of a pulley for driving a belt for driving an auxiliary machine, since chemicals such as calcium chloride used as a snow melting agent may be applied, it is not preferable that chemical resistance is inferior. Moreover, the outer ring | wheel which externally fits this pulley is formed with ferrous metals, such as bearing steel. Therefore, the magnesium alloy pulley and the ferrous metal outer ring are in contact with different metals. For this reason, there is a possibility that electrolytic corrosion occurs on the contact surface between the pulley and the outer ring.
In addition, there exists a technique described in the nonpatent literature 1-2 as a technique relevant to this invention.

JP 7-91525 A JP 2003-269581 A “Citizen's Low Temperature Plasma Technology DLC Diamond Like Carbon”, [online], Citizen Watch Co., Ltd. [Search June 29, 2005], Internet <URL: http://www.citizen.co.jp/dlc/dlc4 .htm> “Alpha Logos S-DLC”, [online], Oriental Engineering Co., Ltd. [searched on August 10, 2005], Internet <URL: http://www.oriental-eg.co.jp/cor/dlc.html >

  The rolling bearing with pulley of the present invention is excellent in wear resistance and chemical resistance even when the pulley is made of a magnesium alloy in view of the circumstances as described above, and electrocorrosion occurs at the contact surface between different metals. Invented to realize a structure capable of preventing the above.

The pulley-equipped rolling bearing according to the present invention includes a rolling bearing and a pulley, as in the conventional structure described above.
Of these, the rolling bearing includes an inner ring having an inner ring raceway on an outer peripheral surface, an outer ring having an outer ring raceway on an inner peripheral surface, and a plurality of rolling elements provided between the inner ring raceway and the outer ring raceway so as to be freely rollable. With.
Further, the pulley is formed in an annular shape as a whole and is fixed around the outer ring.
In particular, in the rolling bearing with pulley of the present invention, the pulley is made of a magnesium alloy, and at least a part of the surface of the pulley is a hard carbon film {DLC (Diamond Like Carbon) film} Covered by.
Part of the surface of the pulley covered with the hard carbon film (hereinafter referred to as DLC film) is, for example, a part covering the outer ring, a part exposed in a state where the pulley is fixed to the outer ring, depending on use conditions Furthermore, the entire surface of the pulley is used.

  If a part of the surface of the pulley covered with the DLC film is a part covering the outer ring, the DLC film can be interposed between the pulley and the outer ring. As a result, even if the outer ring and the pulley are made of different metals, it is possible to prevent electrolytic corrosion from occurring on the contact surface between these two members (in the magnesium alloy pulley). That is, as described in Non-Patent Document 1 described above, since the DLC film is excellent in insulation, it is possible to prevent electrolytic corrosion from occurring on the contact surface by interposing the DLC film on the contact surface. .

  Further, if a part of the surface of the pulley covered with the DLC coating is exposed when the pulley is fixed to the outer ring, even if the pulley is made of a magnesium alloy, the exposed portion Abrasion resistance and chemical resistance can be improved. That is, as described in Non-Patent Document 1, since the DLC film is excellent in wear resistance and chemical resistance, by covering the exposed portion with the DLC film, the wear resistance of the pulley and Chemical resistance can be improved. If the entire surface of the pulley is covered with the DLC film, the wear resistance and chemical resistance of the pulley can be improved, and electrolytic corrosion can be prevented from occurring on the contact surface with the outer ring.

  In the case of the present invention, since the pulley is made of a magnesium alloy, the weight can be reduced as compared with a ferrous metal pulley. Furthermore, the magnesium alloy is excellent in heat dissipation compared with the synthetic resin. As described in Non-Patent Document 2, the DLC film has a high thermal conductivity. Therefore, even if the pulley is covered with the DLC film, the heat dissipation is not inferior. For this reason, it is difficult for heat to be applied to the rolling bearing, and the life of the rolling bearing can be extended.

When carrying out the present invention, preferably, as described in claim 2, a hard carbon film (DLC film) is interposed between an outer ring made of a ferrous metal such as bearing steel and a pulley. For this purpose, at least one of a part of the pulley surface covering the outer ring and a part of the outer ring surface covered by the pulley is covered with the DLC film. .
If comprised in this way, as mentioned above, it can prevent that electrolytic corrosion arises in the contact surface of the pulley made from a magnesium alloy and the outer ring made from a ferrous metal which are dissimilar metals.
Preferably, the exposed portion of the surface of the pulley is covered with a hard carbon film (DLC film) in a state where the pulley is fixed to the outer ring.
With this configuration, as described above, even when the pulley is made of a magnesium alloy, the wear resistance and chemical resistance of the exposed portion can be improved.

  FIG. 1 shows a first embodiment of the present invention. The feature of the present embodiment is that even when the pulley 9b is made of a magnesium alloy, in order to obtain a structure that is excellent in wear resistance and chemical resistance and can prevent the occurrence of electrolytic corrosion on the contact surface with the outer ring 13. The surface of the pulley 9b is covered with a hard carbon film (DLC film). The basic structure and operation of the pulley-equipped rolling bearing are the same as those of the conventional structure shown in FIGS. For this reason, the same reference numerals are given to the equivalent parts, and overlapping explanations are omitted or simplified. Hereinafter, the characteristic parts of this embodiment and parts different from the conventional structure will be mainly described.

  The pulley 9b is made by metal injection (metal injection) of a magnesium alloy (for example, AZ80). That is, molten magnesium alloy is injected into a cavity for forming the pulley 9b to form the pulley 9b. The pulley may be formed by performing plastic processing such as forging or cutting processing such as turning. In this case, the shape of the pulley is preferably a simple shape as shown in FIG. In the case of the present embodiment, the pulley 9b is made by metal injection, so that the pulley 9b is concentrically provided on the inner diameter side, similar to the conventional synthetic resin pulley 9a shown in FIG. It has a cylindrical portion 15a and an outer diameter side cylindrical portion 16a. The outer peripheral surface of the intermediate portion of the inner diameter side cylindrical portion 15a and the inner peripheral surface of the intermediate portion of the outer diameter side cylindrical portion 16a are connected by a ring-shaped connecting portion 17a, and a plurality of each are provided on both side surfaces of the connecting portion 17a. Reinforcing ribs 18a and 18a are provided radially.

  Further, the pulley 9b has an inward flange portion 19 projecting radially inward only at one end portion (right end portion) in the width direction (left and right direction in FIG. 1) of the inner diameter side cylindrical portion 15a. The inner circumferential surface of the other end (left end) in the width direction is a simple cylindrical surface. Furthermore, in the case of the present embodiment, the outer peripheral surface of the outer diameter side cylindrical portion 16a has a cross-sectional shape of a poly V on the outer peripheral surface of the outer diameter side cylindrical portion 16a as a waveform extending in the width direction (left and right direction in FIG. 1). A part of the inner peripheral surface of an endless belt called a belt, in which a plurality of protrusions are formed on the inner peripheral surface, is freely hangable.

  In this embodiment, the entire surface of the pulley 9b is covered with a DLC film. That is, as described below, in a state where the pulley 9b is externally fitted and fixed to the outer ring 13 constituting the rolling bearing 8, not only the portion where the surface of the pulley 9b is exposed but also the surface of the pulley 9b, The portion covering the outer ring 13 (the inner circumferential surface of the inner diameter side cylindrical portion 16a to the inner side surface of the inward flange portion 19) is also covered with the DLC film. In this embodiment, after the entire surface of the pulley 9b is covered with the DLC film, the pulley 9b is fitted and fixed to the outer ring 13 by an interference fit. At this time, the inner diameter side cylindrical portion 16a is externally fitted and fixed to the outer ring 13 from the other end in the width direction, which is the side where the inward flange portion 19 is not formed (the side that is simply a cylindrical surface). Then, the inner surface of the inward flange portion 19 formed at one end in the width direction is brought into contact with the end surface of the outer ring 13 to position the pulley 9b with respect to the outer ring 13. In this state, the DLC film is present between the pulley 9 b and the outer ring 13.

  As described above, in the case of the rolling bearing with pulley 6b of this embodiment, since the entire surface of the pulley 9b is covered with the DLC film, even if the pulley 9b is made of a magnesium alloy, the surface of the pulley 9b The wear resistance and chemical resistance of the metal can be improved, and further, electrolytic corrosion due to contact with dissimilar metals can be prevented. First, since the portion exposed when the pulley 9b is externally fitted to the outer ring 13 is covered with the DLC film having excellent wear resistance, it is caused by rubbing with the belt that passes over the pulley 9b during use. The wear of the pulley 9b can be reduced. Even if a chemical such as a snow melting agent is applied to the pulley 9b, the DLC film is excellent in chemical resistance, so that the pulley 9b can be prevented from being corroded by the chemical.

  Next, since the portion of the surface of the pulley 9b that covers the outer ring 13 is also covered with the DLC film, the DLC film is interposed between the pulley 9b and the outer ring 13. Since this DLC film is also excellent in insulation, it is possible to prevent electrolytic corrosion from occurring on the contact surface between the pulley 9b made of magnesium alloy and the outer ring 13 made of bearing steel, which are different metals. In this embodiment, the portion of the surface of the pulley 9b that covers the outer ring 13 is covered by the DLC film, but the portion of the surface of the outer ring 13 that is covered by the pulley 9b is You may make it cover with the said DLC film. In this case, the portion of the surface of the pulley 9b that covers the outer ring 13 may or may not be covered with a DLC film. In any case, it suffices if the DLC film can be interposed between the pulley 9b and the outer ring 13.

  In the case of this embodiment, since the pulley 9b is made of a magnesium alloy, the weight can be reduced as compared with the iron-based metal pulley as in the invention described in Patent Document 2 described above. Further, the magnesium alloy is excellent in heat dissipation compared with the synthetic resin, and the DLC film covering the pulley 9b has a high thermal conductivity. For this reason, the heat generated inside the rolling bearing 8 during operation can be efficiently transmitted to the pulley 9b, and the heat transmitted to the pulley 9b can be efficiently released to the outside. Therefore, it is difficult for heat to get inside the rolling bearing 8. And the deterioration of the grease enclosed in the rolling bearing 8 can be suppressed, and the life of the rolling bearing 8 can be extended.

  FIG. 2 shows a second embodiment of the present invention. In the case of the present embodiment, the outer peripheral surface of the outer diameter side cylindrical portion 16b constituting the pulley 9c is a simple cylindrical surface in accordance with the shape of the belt spanning the outer peripheral surface. Further, in the case of the present embodiment, a concave groove 20 inclined with respect to the circumferential direction is formed on the outer peripheral surface of the outer ring 13a made of bearing steel constituting the rolling bearing 8 over the entire circumference. In addition, at least the outer peripheral surface or the width direction (the left-right direction in FIG. 2) both ends of the outer ring 13a are covered with the DLC coating over the entire periphery. That is, in this embodiment, before fixing the pulley 9c around the outer ring 13a, at least a portion of the surface of the outer ring 13a that is covered by the inner cylindrical portion 15b of the pulley 9c is the DLC. It is covered with a film. In this state, as described below, the pulley 9c is fixed around the outer ring 13a.

  The pulley 9c is formed by injecting molten metal alloy into this cavity (metal injection) with the outer diameter side portion of the outer ring 13a set in the cavity for molding the pulley 9c. is doing. As a result, the pulley 9c is fixed (coupled and fixed) around the outer ring 13a with the outer diameter side portion of the outer ring 13a embedded in the inner diameter side. In addition, this DLC film may be combined with oxygen in the atmosphere at a high temperature to be thin. However, since the heat capacity of the outer ring 13a covered with the DLC film is large, even if a high-temperature molten magnesium alloy comes into contact with the DLC film during the metal injection, the temperature rise of the DLC film can be suppressed. That is, the melting temperature of the magnesium alloy is about 600 ° C., while the outer ring 13a is at room temperature (for example, 20 ° C.). In addition, after the molten magnesium alloy is injected, the DLC film is rapidly cooled, so that the time during which the DLC film is exposed to a high temperature is short. Therefore, the DLC film does not rise above the heat-resistant temperature (about 400 ° C.) during metal injection. For this reason, the DLC film is not damaged during metal injection.

  Further, in the case of this embodiment, in the above-described metal injection, the inner peripheral surface of the pulley 9c is aligned with the groove 20 formed on the outer peripheral surface of the outer ring 13a over the entire periphery. A ridge 21 is formed. The engagement between the concave grooves 20 and the protrusions 21 prevents so-called creep in which the outer ring 13a and the pulley 9c rotate relative to each other. Of course, the surface of the groove 20 is also covered with the DLC film. In the case of this embodiment, inward flange portions 19 and 19 projecting inward in the radial direction are formed over the entire circumference at both ends in the width direction of the inner diameter side cylindrical portion 15b constituting the pulley 9c. ing. The inward flange portions 19 and 19 sandwich the outer diameter portion of the outer ring 13a from both sides in the width direction to achieve positioning in the axial direction.

  As described above, with the pulley 9c fixed on the outer diameter side of the outer ring 13a, the exposed portion of the surface of the pulley 9c is covered with the DLC film. That is, of the surface of the pulley 9c, a portion other than the portion covering the outer ring 13a (the inner peripheral surface of the inner diameter side cylindrical portion 16a or the inner surface of the inward flange portions 21, 21) is covered with the DLC film. However, the portion of the outer ring 13a covered by the pulley 9c is covered by the DLC film as described above. For this reason, in a state where the pulley 9c is fixed around the outer ring 13a, the DLC film comes into contact with a portion of the surface of the pulley 9c that covers the outer ring 13a. Therefore, in this embodiment, the DLC film is present between the outer ring 13a and the pulley 9c in a state where the pulley 9c is formed on the outer diameter side portion of the outer ring 13a. Other structures and operations are the same as those of the first embodiment.

  In each of the above-described embodiments, the case where a single-row ball bearing is used as the rolling bearing has been described. However, the present invention is not limited to a double-row ball bearing, or a single-row or double-row roller. The present invention can also be applied to a bearing. In addition to the structure for applying a desired tension to the belt as shown in FIG. 3, the apparatus incorporating the pulley-equipped rolling bearing according to the present invention can be used for a pulley for guiding the belt, for example. It is. In short, any structure can be applied as long as the pulley and the rolling bearing are integrated.

  In each of the above-described embodiments, a DLC film is interposed between the outer ring and the pulley. However, as in the case of the timing belt, the roller bearing with pulley is used in a state where it is difficult to get water or the like. In the case where electrolytic corrosion is unlikely to occur at the contact surface between the outer ring and the pulley, the DLC film need not be interposed on the contact surface. In particular, in the case of Example 2, there is a step of covering the outer ring with the DLC film separately from the pulley. Therefore, if it is not necessary to interpose the DLC film on the contact surface, the step of covering the outer ring with the DLC film is reduced. Thus, the manufacturing cost can be reduced.

FIG. 2 is a half sectional view showing Example 1 of the present invention. FIG. 6 is a half sectional view showing the second embodiment. The front view of the tension | tensile_strength provision apparatus incorporating the 1st example of the conventional structure. AA sectional drawing of FIG. The partially cut perspective view which shows the 2nd example of a prior art structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base plate 2 Long hole 3 Support shaft 4 Head 5 Adjustment bolt 6, 6a, 6b Rolling bearing with pulley 7 Sleeve 8, 8a Rolling bearing 9, 9a, 9b, 9c Pulley 10 Inner ring track 11 Inner ring 12 Outer ring track 13, 13a Outer ring 14 ball 15, 15a, 15b inner diameter side cylindrical portion 16, 16a, 16b outer diameter side cylindrical portion 17, 17a connecting portion 18, 18a reinforcing rib 19 inward flange portion 20 concave groove 21 ridge

Claims (3)

  A rolling bearing including an inner ring having an inner ring raceway on an outer peripheral surface, an outer ring having an outer ring raceway on an inner peripheral surface, and a plurality of rolling elements provided between the inner ring raceway and the outer ring raceway so as to be freely rollable; , A pulley-type rolling bearing comprising an annular ring and a pulley fixed around the outer ring, wherein the pulley is made of a magnesium alloy, and at least a part of the surface of the pulley is made of a hard carbon film. Rolling bearing with pulley, characterized by being covered.   The rolling bearing with a pulley according to claim 1, wherein a hard carbon film is interposed between an iron-based metal outer ring and the pulley. The rolling bearing with a pulley according to claim 1 or 2, wherein an exposed portion of the surface of the pulley is covered with a hard carbon film in a state where the pulley is fixed to the outer ring.

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