JP2007315594A - Constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve constant velocity accuracy while preventing balls from falling off of pockets during assembly and disassembly work in a constant velocity joint having a cage made of synthetic resin moulded article. <P>SOLUTION: Interference in a cage circumference direction is provided between an inner circumference of the pocket 12 and the balls 20 to prevent the balls from falling off of the pockets 12 by their own weight, and to prevent rattle of the balls 20. A lubricating film is formed on track grooves 6, 7 of an outer ring 1, and balls 20 is formed out of synthetic resin or lubricating film is formed on a surface thereof to eliminate lubrication. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a constant velocity joint that connects two shafts, a drive shaft and a driven shaft, and transmits the power of the drive shaft to the driven shaft.

  Conventionally, a constant velocity joint is known as a component for transmitting rotational torque of a drive shaft of an automobile to an axle.

  The constant velocity joint is a member that allows the angular displacement of both shafts while maintaining constant velocity between the drive shaft and the driven shaft, and is therefore frequently used in various industrial machines other than automobiles.

  The constant velocity joint includes a fixed type constant velocity joint that allows only angular displacement and a sliding type constant velocity joint that allows angular displacement and axial displacement.

  As the sliding type constant velocity joint, as shown in FIGS. 6 and 7, one having an outer ring 51, a cage 52, and three balls 53 is known. An annular space 55 is formed in the outer ring 51 by providing a guide shaft 54 on the inner axis. In the cage 52 incorporated in the annular space 55, pockets 56 for holding the balls 53 are formed at intervals of 120 ° in the circumferential direction. At least one of the outer wall surface and the inner wall surface of the annular space 55 is provided with three track grooves 57 and 58 extending in the axial direction at positions corresponding to the pockets 56 at intervals of 120 ° in the circumferential direction. . The balls 53 incorporated in the pockets 56 can roll along the track grooves 57, 58, and transmit rotational torque between the outer ring 51 and the cage 52 via the balls 53. It has become.

  In the constant velocity joint as shown in FIGS. 6 and 7, when various parts are made of metal such as steel, the strength is high but the grease lubrication is necessary. Such a thing has characteristics, such as loud operation sound, and a use location is restrict | limited. For example, it is not suitable for equipment used under conditions where quietness and grease scattering are not allowed, such as food manufacturing equipment, medical equipment, office equipment, household appliances, and acoustic equipment.

  For this reason, various parts of the constant velocity joint are formed of synthetic resin, and by reducing the weight of the various parts, there is a case in which grease lubrication is unnecessary and operation noise is reduced (see Patent Document 1).

JP 2006-38204 A

However, in the constant velocity joint as shown in FIGS. 6 and 7, when the outer ring 51 and the cage 52 are separated when the assembly and disassembly work is performed for breakage, replacement of consumables, etc., the pocket 56 becomes the outer ring 51. When the ball 53 comes out of the box, the balls 53 fall off from the pockets 56 and fall into the cage 52 or fall from the cage 52, so that there is a problem of poor workability.
Further, as a general problem with constant velocity joints, constant velocity accuracy between the two axes of the drive shaft and the driven shaft is required.

  Therefore, an object of the present invention is to improve the constant velocity accuracy while preventing the balls from dropping from the pockets during assembly and disassembly work in a constant velocity joint whose cage is made of a synthetic resin product.

  In order to achieve the above object, the present invention has an annular space with one end opened, and three track grooves extending in the axial direction on at least one of an outer wall surface and an inner wall surface of the annular space are 120 ° in the circumferential direction. An outer ring formed at intervals of the outer ring, a cage incorporated in the annular space of the outer ring, and a pocket formed at a position corresponding to each of the track grooves, and incorporated in each pocket of the cage. In a constant velocity joint including a ball that can roll along a track groove, the cage is a synthetic resin molded product, and the outer ring is made of metal or ceramics, and the ball and the inner periphery of the pocket A configuration is adopted in which the ball is held on the inner periphery of the pocket by providing an allowance in the cage circumferential direction.

  Specifically, the cage is detached from the outer ring by adopting a configuration in which the ball is held on the inner periphery of the pocket by providing a margin in the cage circumferential direction between the ball and the inner periphery of the pocket. Even in this state, the ball is clamped and held on the inner periphery of the pocket. Therefore, the constant velocity joint provided with the cage can prevent the ball from falling out of the pocket during assembly and disassembly, and as a result, these operations can be easily performed.

Further, since the ball is clamped and held in the cage circumferential direction on the inner circumference of the pocket, a preload in the cage circumferential direction is applied to the ball by the cage. For this reason, the ball does not rattle in the pocket when the constant velocity joint is operated.
Therefore, according to the above configuration, it is possible to improve the constant velocity accuracy while preventing the ball from dropping from the pocket during assembly and disassembly work.

  In the above configuration, if the configuration in which the part holding the ball is recessed from the other part of the inner periphery of the pocket is adopted, the ball is difficult to move in the holding state, and the constant velocity joint is assembled. The ball can be securely held in place in the pocket.

  Further, in the above configuration, if a configuration is adopted in which the pocket is a cylindrical hole and the inner diameter thereof is smaller than the ball diameter of the ball, it is not necessary to forcibly remove the core pin forming the pocket, and the cage injection molding is facilitated. Can be implemented.

  In the above configuration, if the lubricity of the rolling surface of the ball is increased, a constant velocity joint can be used without lubrication.

  Specifically, in the above configuration, a configuration in which a lubricating film is formed in the track groove of the outer ring can be employed.

  The ball may be made of a synthetic resin or may have a structure in which a lubricating film is formed on the surface.

  In particular, the lubricating coating is preferably composed of one of a resin coating, a diamond-like carbon coating, and a composite plating.

  More preferably, the resin film contains a fluororesin.

  As described above, according to the present invention, by adopting the above-described configuration, in a constant velocity joint in which the cage is formed of a synthetic resin, the constant velocity accuracy is improved while preventing the ball from dropping from the pocket during assembly and disassembly work. Can be achieved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 and 2 show the overall structure of a constant velocity joint according to an embodiment of the present invention. As illustrated, the constant velocity joint according to the embodiment includes an outer ring 1, a cage 10 and a ball 20.

  The outer ring 1 has a cup portion 2 that is open at one end, and a first shaft 3 is integrally provided at the closed end of the cup portion 2.

  Further, a guide shaft 4 is provided on the central axis in the cup portion 2, an annular space 5 is formed between the guide shaft 4 and the cup portion 2, and the cup portion 2 that forms the outer wall surface of the annular space 5 is formed. Three track grooves 6 and 7 extending in the axial direction are provided on the outer peripheral surface of the guide shaft 4 that forms the inner peripheral surface and the inner wall surface of the annular space 5 at intervals of 120 ° in the circumferential direction. Although the track grooves 6 and 7 are formed on the outer wall surface and the inner wall surface of the annular space 5, respectively, the track groove may be provided on one of the outer wall surface and the inner wall surface.

  The outer ring 1 is made of metal or ceramics. The metal that can be used may be any metal such as iron, aluminum, and copper. You may manufacture by any of die-casting, shaving, and sintering. An aluminum die-cast or iron-based sintered body is preferable.

  Further, as shown in FIG. 3, by forming a lubricious film Sc on the track grooves 6 and 7 of the outer ring, it can be used without lubrication even though a metal or ceramic outer ring is used. it can.

  As the lubricating film Sc, for example, a resin film such as a fluororesin, a molybdenum disulfide film, a graphite film, a diamond-like carbon film, nickel phosphor plating, a composite plating such as a fluorine resin-containing nickel plating, or the like can be employed.

  Above all, the fluororesin film, diamond-like carbon film, and composite plating have excellent lubrication characteristics, so the lubricity of the ball rolling surface of the constant velocity joint can be further improved, resulting in lower torque and power saving. it can.

  As the fluororesin film, a resin film in which a fluororesin solid lubricant is blended with a binder resin can be employed. Specifically, there are those using a polyimide resin, a polyamideimide resin (PAI), an epoxy resin, a phenol resin, or the like as the binder resin and a polytetrafluoroethylene resin (PTFE) as the solid lubricant fluororesin. In addition to PTFE, graphite and molybdenum disulfide may be used in combination as the solid lubricant. Particularly preferred is a fluororesin film in which PTFE and graphite are blended with polyimide resin or PAI. The fluororesin film has high lubricity and wear resistance, and can be used for a long time even without lubrication. In addition, since the film thickness can be 10 μm to 100 μm, an effect can be obtained by reducing the operating sound during torque transmission.

  As shown in FIGS. 1, 2, and 4, the cage 10 is incorporated in the annular space 5 of the outer ring 1, and a second shaft is provided at an end portion of the cage 10 located on the opening end side of the annular space 5. 11 is provided integrally.

  The cage 10 is formed with pockets 12 corresponding to the three track grooves 6 and 7 of the outer ring 1, and the balls 20 are incorporated in the pockets 12. Each of the balls 20 can roll along the track grooves 6 and 7.

  The cage 10 is a molded product of synthetic resin that can be injection molded.

  The pocket 12 is a cylindrical hole in which an opening end on the cage inner diameter side and an opening end on the cage outer diameter side have the same inner diameter d, and the inner diameter in the intermediate portion in the cage radial direction is larger than the inner diameter d. It has become.

  The inner diameter of the pocket 12 is smaller than the ball diameter D of the ball 20 in the entire area. For this reason, a clamping margin in the cage circumferential direction is provided between the inner periphery of the ball 20 and the pocket. As a result, the ball 20 is held on the inner periphery of the pocket 12 even when the cage 10 is detached from the outer ring 1 due to the inner periphery of the pocket 12 tightening the ball 20. Therefore, the constant velocity joint provided with the cage 10 can prevent the ball 20 from dropping out of the pocket 12 during assembly and disassembly operations, and as a result, these operations can be easily performed.

Further, since the ball 20 is clamped and held on the inner periphery of the pocket 12 in the circumferential direction of the cage, a preload in the cage circumferential direction is applied to the ball 20 by the cage 10. For this reason, the ball 20 does not rattle in the pocket 12 when the constant velocity joint is operated. Therefore, the constant velocity joint according to this embodiment can improve the constant velocity accuracy while preventing the ball 20 from dropping from the pocket 12 during assembly and disassembly work.
Here, the above-described tightening and holding allows the ball 20 to roll so as not to hinder the operation of the constant velocity joint, and prevents the ball 20 from dropping due to its own weight when the cage 10 is removed from the outer ring 1. You can do it. Specifically, the tightening allowance (ball diameter D−pocket diameter d) may be set to be 1/10000 to 1/200 smaller than the ball diameter D. If the tightening margin is less than 1 / 10000D, the effect of preventing the ball from being lost may not be obtained at a place where the ambient temperature is high, and if it is greater than 1 / 200D, the operation of the constant velocity joint may be hindered.

  Here, in the constant velocity joint according to this embodiment, the other part of the inner periphery of the pocket 12 except for the part 12a that holds the ball 20 has an inner diameter d of both opening end parts. The inner diameter of the portion 12a (hereinafter referred to as the ball holding portion 12a) for holding the ball is larger than the inner diameter d of the other portion. As a result, the ball holding portion 12a is recessed from the other portion, and the ball 20 is tightened in the circumferential direction of the cage at this recessed portion. As a result, a resistance is generated when the ball 20 moves in the cage radial direction in the holding state, and the movement of the ball 20 is prevented. Therefore, the constant velocity joint according to this embodiment improves the constant velocity accuracy, and can securely hold the ball at a fixed position in the pocket in the assembly process at the time of manufacture, so that it is difficult to drop off.

  In the constant velocity joint according to this embodiment, in order to simplify the inner peripheral shape of the pocket 12 and facilitate molding, the allowance is reduced by setting the inner diameter of the pocket 12 to be negative with respect to the ball diameter D of the ball 20. Provided. In this case, the ball 20 is tightened in the cage circumferential direction, and as a result, the ball 20 is also tightened in the radial direction over the entire circumference of the ball 20. Such a configuration is advantageous in that the ball 20 is very stable at the ball holding portion 12a, so that the work of assembling the ball into the cage in the manufacturing process becomes more reliable. The indented portion does not need to be formed over the entire inner periphery of the pocket, and may be a single concave shape as long as the ball can be held in place.

Note that, in the constant velocity joint according to this embodiment, the ball holding portion 12a is recessed from the other portion, and as a result, this portion is undercut during injection molding. An example of avoiding this undercut is shown in FIG. In the example shown in FIG. 5, the pocket 12 is a cylindrical hole over the entire area, and the inner diameter d is smaller than the ball diameter D of the ball 20. In this case, it is not necessary to forcibly remove the core pin forming the pocket 12, and the injection molding of the cage 10 can be easily performed. The configuration as shown in FIG. 4 is suitable when priority is given to constant speed accuracy because the molding accuracy of the pocket 12 is higher than the ease of the manufacturing process. In addition, the life of the mold can be extended.
Considering the above advantages, the constant velocity joint shown in FIG. 5 has a very small operating angle and a small amount of relative movement in the axial direction between the cage 10 and the outer ring 1 like the constant velocity joint for OA equipment. Is preferred. This is because the rolling of the ball 20 is slight, and even if the ball 20 is tightened in the radial direction over the entire circumference, the operation of the constant velocity joint is unlikely to occur.

  What is necessary is just to select an appropriate thing for the said synthetic resin according to the use conditions of a constant velocity joint. For example, the synthetic resin may be either a thermoplastic resin or a thermosetting resin, and may be either a crystalline resin or an amorphous resin. Note that since the non-crystalline resin has a relatively low toughness, the crystalline resin is more preferable in that abrupt destruction can be avoided.

  Preferred synthetic resins include synthetic resins having excellent lubrication characteristics, such as polyacetal resin (POM), nylon resin, injection-moldable fluororesins such as PFA, FEP, and ETFE, injection-moldable polyimide resins, and polyphenylene sulfide resins ( PPS), wholly aromatic polyester resin, polyetheretherketone resin (PEEK), polyamideimide resin and the like.

  Each of the above resins may be a single or polymer alloy. Or the polymer alloy which mix | blended the said resin with resin with low lubrication characteristics other than the above may be sufficient.

  Moreover, even if it is resin with a low lubrication characteristic, if lubrication performance is improved by adding a solid lubricant and lubricating oil, it can be used. Examples of the solid lubricant include polytetrafluoroethylene, graphite, and molybdenum disulfide.

  Moreover, glass fiber, carbon fiber, and various mineral fibers (whiskers) may be added to the synthetic resin to increase the strength, and it may be used in combination with the solid lubricant and the like.

  The most suitable materials for molding the cage 10 and the like are POM, nylon resin, PPS, and PEEK. The nylon resin may be nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 46, semi-aromatic nylon having an aromatic ring in the molecular chain, or the like. Since POM, nylon resin, and PPS are excellent in heat resistance and lubricity and relatively inexpensive, a constant velocity joint excellent in cost effectiveness can be obtained by using these. Moreover, PEEK is excellent in mechanical strength and lubricity even if a reinforcing material and a lubricant are not blended. Therefore, when this is used, a high-performance constant velocity joint can be obtained.

  As described above, by using the cage 10 as a molded product of a synthetic resin, a constant velocity joint that is lightweight and has low operation sound can be obtained. For this reason, the constant velocity joint which concerns on this embodiment is hard to receive the restriction | limiting of a use location, and can be used for various apparatuses.

  The ball 20 may be a ball of bearing steel, stainless steel, ceramics, synthetic resin or the like, but is preferably made of stainless steel, ceramics, or synthetic resin because no rust problem occurs even without lubrication. If it is a synthetic resin, it is preferable at the point by which weight reduction and silence are implement | achieved.

  When the constant velocity joint is used for a medical device or a food production device, it is preferable that the ball 20 is made of stainless steel or ceramic because environmental concerns are eliminated. Moreover, in order to give a hygienic impression, when using a synthetic resin, a white thing is preferable. POM is suitable in that it is white, has high lubricity, and can be made grease-free.

  When the ball 20 is made of metal such as bearing steel or stainless steel, or ceramics, by forming a lubricating film on the surface of the ball 20, it is possible to reduce lubrication and reduce operating noise during torque transmission. it can.

The lubricating film (not shown) formed on the surface of the ball 20 can be selected from the films exemplified for the lubricating film Sc of the track grooves 6 and 7.
Among these, the fluororesin film, the diamond-like carbon film, and the composite plating are preferable in that the lubricity of the ball rolling surface of the constant velocity joint can be further improved.
The fluororesin film has high lubricity and wear resistance, and can be used for a long time even without lubrication. In addition, since the film thickness can be 10 μm to 100 μm, an effect can be obtained by reducing the operating sound during torque transmission.

  As described above, since the ball 20 is held on the inner periphery of the pocket 12, the constant velocity joint can be easily assembled and disassembled by inserting / removing the cage 10 into / from the annular space 5 of the outer ring 1.

  In particular, this embodiment eliminates lubrication by the lubricating coating Sc, so that a boot or the like is not required, and the cage 10 can be directly inserted into and removed from the annular space 5 of the outer ring 1. Combined with the effect, the constant velocity joint can be assembled and disassembled quickly. As a result, it is possible to easily replace the input side component that inputs power to the constant velocity joint or the output side component that is rotationally driven by the output from the constant velocity joint. For this reason, the constant velocity joint according to this embodiment is often disassembled and assembled at the installation site, and is suitable for office equipment that takes time to take out when the ball falls into the equipment.

  In this embodiment, as shown in FIG. 1, an annular space is formed at the opening end of the track groove 6 formed on the inner peripheral surface of the cup portion 2 and the track groove 7 formed on the outer peripheral surface of the guide shaft 4. Taper surfaces 13 and 14 having large diameter ends at the open ends of the outer wall surface and the inner wall surface are provided.

  The tapered surfaces 13 and 14 guide the ball 20 toward the open ends of the track grooves 6 and 7 when the cage 10 is assembled into the cup portion 2. For this reason, the ball 20 is inserted into the track grooves 6 and 7 by relatively rotating the outer ring 1 and the cage 10 while the ball 20 is guided by the tapered surfaces 13 and 14. Therefore, in this embodiment, the constant velocity joint can be easily assembled even when the track grooves 6 and 7 and the ball 20 are out of phase with each other.

  The tapered surfaces 13 and 14 can be, for example, a tapered surface having an axial center on the central axis of the outer ring 1 or a tapered surface having an axial center on the pitch circle of the ball 20. Guide protrusions can also be formed between adjacent tapered surfaces.

  In this embodiment, the cage 10 and the second shaft 11 are integrally formed of synthetic resin. However, the second shaft 11 is formed of a metal such as ceramics, steel, stainless steel, or aluminum alloy, and the cage is formed of synthetic resin. You may couple | bond with 10 and coupling | bonding means, such as a volt | bolt.

Vertical section of constant velocity joint according to an embodiment Sectional view taken along line II-II in FIG. Partially enlarged vertical sectional view showing another example of the outer ring of FIG. Plan view showing the pocket of FIG. 1 from the outer diameter side Partially enlarged longitudinal sectional view showing another example of the pocket of FIG. Longitudinal sectional view of conventional constant velocity joint Sectional drawing of the VII-VII line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Cup part 4 Guide shaft 5 Annular space 6, 7 Track groove 10 Cage 12 Pocket 12a Ball holding part 20 Ball Sc Lubricious film

Claims (7)

An outer ring having an annular space with one end open, and three track grooves extending axially on at least one of an outer wall surface and an inner wall surface of the annular space at intervals of 120 ° in the circumferential direction; A cage in which a pocket is formed at a position corresponding to each of the track grooves, and a ball which is incorporated in each pocket of the cage and rolls along the track groove. In the provided constant velocity joint,
The cage is a molded product of synthetic resin, the outer ring is made of metal or ceramics, and the ball is placed on the inner periphery of the pocket by providing a tightening margin in the cage circumferential direction between the inner periphery of the ball and the pocket. A constant velocity joint characterized by being held.   The constant velocity joint according to claim 1, wherein a portion of the inner periphery of the pocket that holds the ball is recessed from other portions.   The constant velocity joint according to claim 1, wherein the pocket is a cylindrical hole, and an inner diameter thereof is smaller than a ball diameter of the ball.   The constant velocity joint according to any one of claims 1 to 3, wherein a lubricant film is formed in a track groove of the outer ring.   The constant velocity joint according to any one of claims 1 to 4, wherein the ball is made of a synthetic resin or has a lubricating film formed on a surface thereof.   The constant velocity joint according to claim 4 or 5, wherein the lubricating coating is made of one of a resin coating, a diamond-like carbon coating, and a composite plating.   The constant velocity joint according to claim 6, wherein the resin film contains a fluororesin.

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