JP5893884B2 - Chain guide and chain transmission - Google Patents

Description

  The present invention relates to a chain guide for guiding travel of a torque transmission chain and a chain transmission device using the chain guide.

  The automobile engine transmits the rotation of the crankshaft to a camshaft via a timing chain (hereinafter simply referred to as “chain”), and opens and closes the valve of the combustion chamber by the rotation of the camshaft.

  Such a camshaft drive chain transmission device includes a drive sprocket attached to the crankshaft, a driven sprocket attached to the camshaft, a chain spanned between the drive sprocket and the driven sprocket, and the chain. A swingable chain guide disposed on the slack side, a chain tensioner that presses the chain guide toward the chain, and a fixed chain guide disposed on the tension side of the chain are often used.

  Here, the chain guide on the swing side keeps the chain tension constant by pressing the chain with the urging force of the chain tensioner, and the chain guide on the fixed side keeps the ideal chain travel line while maintaining the chain's tension. Suppresses vibration.

  As a swing side chain guide and a fixed side chain guide used in such a chain transmission device, there is known a type in which a guide surface extending along the chain traveling direction is in sliding contact with the chain. However, the chain guide has a problem that the running resistance of the chain is large and the torque transmission loss is large since the contact with the chain is a sliding contact.

  In order to solve such problems, the inventors of the present invention have a guide base extending in the running direction of the chain, and a plurality of guide bases attached to the guide base along the same circumference along the running direction of the chain. There has been proposed a chain guide that includes a roller shaft and a roller rotatably supported by each roller shaft, and that guides the chain by rolling with the roller (Patent Document 1).

  This chain guide is characterized in that since the contact with the chain is a rolling contact, the running resistance of the chain is small and the torque transmission loss is small.

International Publication No. 2010/090139

  By the way, in order to evaluate the durability of the above-described chain guide, the inventors of the present invention span a chain between a drive sprocket attached to a crankshaft and a driven sprocket attached to a camshaft. A test machine that guides the running of the machine with a rolling chain guide was manufactured, and an endurance test was performed in which the crankshaft of the test machine was rotated in the red zone region.

  As a result, even after thousands of hours passed in the red zone, it was confirmed that each roller of the chain guide can be used without being damaged and has durability enough to withstand practical use. When the durability test is continued for a longer time, scaly peeling (flaking) may occur on the roller shaft. At this time, the roller shaft that first causes peeling is always the roller shaft at the same position. It has been found that the chain guide reaches the end of its life by peeling off a specific roller shaft.

  The problem to be solved by the present invention is to provide a chain guide having excellent durability.

  The inventors of the present invention focused on the possibility of making the life of each roller uniform and extending the life of the chain guide as a whole by making the load applied to each roller from the chain uniform. If the contact point between the roller and the chain is shifted to the outside with respect to the reference circle drawn along the rollers adjacent to the upstream and downstream sides of the chain in the chain traveling direction, the contact point is shifted to the outside. We found that the load applied to the rollers tends to be larger than the load applied to the rollers adjacent to the upstream side and the downstream side, and in order to equalize the load applied to each roller, the contact point between the roller and the chain It is arranged so as not to be shifted outward as much as possible with respect to a reference circle drawn along rollers adjacent to the upstream side and the downstream side.

  Specifically, the contact point between the roller and the chain is within 0.8 mm on the outer side and within 1.0 mm on the inner side from the reference circle drawn along the rollers adjacent to the upstream side and the downstream side in the chain traveling direction. The rollers were arranged so as to be in the range of.

  In this case, the range where the contact point between the roller and the chain exists is within 0.8 mm outside the reference circle drawn along the rollers adjacent to the upstream side and downstream side of the chain in the chain traveling direction. It is possible to prevent the load applied to the specific roller from becoming larger than the load applied to the rollers adjacent to the upstream side and the downstream side in the chain traveling direction. Also, the range where the contact point between the roller and the chain exists is within 1.0 mm inside the reference circle drawn along the rollers adjacent to the upstream and downstream sides of the chain in the chain running direction. It is possible to prevent the load applied to the rollers adjacent to the upstream side and the downstream side of the chain in the chain traveling direction from becoming larger than the load applied to the chain. As a result, the load applied to each roller from the chain can be made uniform, the life of each roller can be made uniform, and the life of the chain guide as a whole can be extended.

  Here, the third and subsequent rollers from the upstream end in the chain running direction and the third and subsequent rollers from the downstream end are based on two rollers adjacent to the upstream side of the roller and two rollers adjacent to the downstream side. Rollers can be arranged using a regression circle as the reference circle.

  For the second roller from the upstream end in the chain running direction, a circumscribed circle that is in contact with the upstream end roller, the third roller from the upstream end, and the fourth roller from the upstream end is used as the reference circle. Can be arranged. Similarly, for the second roller from the downstream end in the chain running direction, a circumscribed circle that is in common contact with the roller at the downstream end, the third roller from the downstream end, and the fourth roller from the downstream end is used as the reference circle. Roller arrangement can be performed.

  The guide base extends in the running direction of the chain and supports a pair of side plates that support both ends of each roller shaft, and a plurality of connections that are arranged between adjacent roller shafts to connect the pair of side plates. The thing of the structure which has a part is employable.

  In the present invention, as a chain transmission device using the above chain guide, the chain spanned between the drive sprocket and the driven sprocket, and the swingable chain guide provided on the slack side of the chain And a chain transmission having a chain tensioner that presses the chain guide toward the chain.

  When a fixed chain guide is further provided on the tension side of the chain, the chain guide can be used for the fixed chain guide.

  In the chain guide of the present invention, the contact point between each roller and the chain is within 0.8 mm outside the reference circle drawn along the rollers adjacent to the upstream side and the downstream side and within 1.0 mm inside. Since each roller is arranged so as to be present in, the load applied to each roller from the chain is made uniform, and it is possible to prevent a specific roller from having a shorter life than other rollers, and as a result, Exhibits excellent durability.

Schematic which shows the chain transmission of embodiment of this invention 1 is a perspective view of the chain guide shown in FIG. 2 is a longitudinal sectional view of the chain guide shown in FIG. Right side view of the chain guide shown in FIG. Sectional view along line VV in FIG. FIG. 5 is an enlarged sectional view of the roller shown in FIG. Exploded front view showing part of guide base and rollers The figure which shows the arrangement | positioning method of the 3rd roller from the upstream of the chain guide shown in FIG. The figure which shows the arrangement | positioning method of the 2nd roller from the upstream of the chain guide shown in FIG. Enlarged view of the third roller shown in FIG. Enlarged view of the second roller shown in FIG.

  FIG. 1 shows a chain transmission device incorporating a chain guide according to an embodiment of the present invention. This chain transmission device spans between a drive sprocket 2 fixedly attached to a crankshaft 1 of an engine, a driven sprocket 4 fixedly attached to a camshaft 3, and the drive sprocket 2 and the driven sprocket 4. The rotation of the crankshaft 1 is transmitted to the camshaft 3 through the chain 5, and the combustion chamber valve (not shown) is opened and closed by the rotation of the camshaft 3.

  When the engine is operating, the rotation direction of the crankshaft 1 is constant (right rotation in the figure). At this time, the chain 5 is stretched on the side that is pulled into the drive sprocket 2 as the crankshaft 1 rotates. The portion on the side that is fed from the drive sprocket 2 is the slack side. On the slack side of the chain 5, there are provided a chain guide 7 that is swingably supported around the fulcrum shaft 6 and a chain tensioner 8 that presses the chain guide 7 toward the chain 5. On the other hand, a fixed chain guide 9 is provided on the tension side of the chain 5.

  The chain guide 7 extends vertically along the chain 5, and a fulcrum shaft 6 is inserted into an insertion hole 10 provided at an upper end portion of the chain guide 7, and is supported to be swingable about the fulcrum shaft 6. A chain tensioner 8 is in contact with the swing end portion of the chain guide 7, and the chain guide 7 is pressed toward the chain 5 by the chain tensioner 8.

  Similarly to the chain guide 7, the chain guide 9 also has a shape extending vertically up and down along the chain 5. The chain guide 9 is fixed by tightening the bolts 14 by inserting bolts 14 into insertion holes 13 provided at both upper and lower ends.

  Here, when the swinging side chain guide 7 and the fixed side chain guide 9 are compared, the swinging side chain guide 7 has an insertion hole 10 for inserting the swinging fulcrum shaft 6 at one end. The chain guide 9 on the fixed side is different from that formed in that the insertion holes 13 for inserting the fixing bolts 14 are formed at both ends, but otherwise the same configuration. It is.

  Therefore, the swing-side chain guide 7 will be described below, and the fixed-side chain guide 9 will be denoted by the same reference numerals and the description thereof will be omitted.

  As shown in FIGS. 2 to 4, the chain guide 7 includes a guide base 15 extending in the traveling direction of the chain 5, and a plurality of guide bases 15 that are attached to the guide base 15 in an arc shape along the traveling direction of the chain 5. It comprises a roller shaft 16 and a roller 17 that is rotatably supported by each roller shaft 16.

  The guide base 15 extends along the running direction of the chain 5 and is disposed between a pair of opposed side plates 18 and 18 that support both ends of each roller shaft 16 and the adjacent roller shafts 16, and the side plates 18 and 18. And a connecting portion 19 for connecting the two. Both ends of the connecting portion 19 are fixed to the side plate 18, and the facing interval of the side plate 18 is maintained. As shown in FIG. 3 and FIG. 7, the opposing surfaces of each side plate 18 communicate with the circular recess 20 that supports the shaft end of the roller shaft 16, and the circular recess 20 communicates from the convex edge of the side plate 18. A shaft introduction groove 21 is provided.

As shown in FIG. 7, the shaft introduction groove 21 is formed in a tapered shape in which the groove width gradually decreases from the convex edge of the side plate 18 toward the circular recess 20, and the shaft of the roller shaft 16 passes through the shaft introduction groove 21. The end is introduced into the circular recess 20. Here, in order to prevent the shaft end of the roller shaft 16 introduced into the circular recessed portion 20 from returning to the shaft introducing groove 21, the width D _{1 of the} narrow portion of the shaft introducing groove 21 is the inner diameter D of the circular recessed portion 20. It is formed to be smaller than ₂ .

The inner diameter D ₂ of the circular recess 20 is slightly smaller in diameter than the outer diameter d of the shaft end of the roller shaft 16 is adapted to fit into the circular recess 20 with interference the axial end of the roller shaft 16.

  The guide base 15 can be formed by injection molding of a synthetic resin containing a fiber reinforcement. As the synthetic resin, for example, polyamide (PA) such as PA66 or PA46 can be used. Glass fiber, carbon fiber, aramid fiber, etc. can be used as the fiber reinforcing material to be blended in the synthetic resin. The guide base 15 may be formed of a light metal such as an aluminum alloy or a magnesium alloy.

  The roller shaft 16 is a solid cylindrical body formed of a steel material such as SUJ2 or SC material, and is subjected to heat treatment in order to improve the surface wear resistance. Examples of the heat treatment include bright quenching and induction quenching.

  As shown in FIGS. 5 and 6, the roller 17 is rotatably mounted on the outer periphery of the roller shaft 16, and the cylindrical outer peripheral surface 17 a of the roller 17 contacts the chain 5 for guidance. Here, the roller 17 is a roller bearing including an outer ring 22, a plurality of rollers 23 incorporated inside the outer ring 22, and a cage 24 that holds these rollers 23. The outer ring 22 is a shell-shaped outer ring formed into a cup shape by drawing a steel plate such as SPC or SCM. Inward flanges 25 are formed at both ends of the outer ring 22.

  The outer diameter of the outer ring 22 is set in a range of 10 mm to 25 mm, and the outer diameters of all the outer rings 22 are the same. The outer ring 22 is a heat-treated product cured by heat treatment, and the wear resistance of the outer peripheral surface 17a is ensured by the heat treatment. Examples of the heat treatment of the outer ring 22 include induction hardening, carburizing treatment, and carbonitriding treatment. Further, the cylindricity of the outer peripheral surface 17a of the outer ring 22 is 20 μm or less in the state after the heat treatment.

  In this embodiment, the roller bearing is used alone as the roller 17 in order to reduce the weight of the roller 17 and minimize the running resistance of the chain 5, but a cylindrical resin is formed on the outer periphery of the outer ring 22 of the roller bearing. A member attached with a member or an iron member may be used as the roller 17, and other types of bearings may be used instead of the roller bearings. Here, the roller bearing refers to a cylindrical roller bearing and a needle roller bearing.

  Each roller 17 has a contact point between the roller 17 and the chain 5 within 0.8 mm outside the reference circle drawn along the rollers 17 adjacent to the upstream side and the downstream side in the running direction of the chain 5 and 1 inside. It arrange | positions so that it may exist in the range within 0.0 mm.

Hereinafter, as shown in FIG. 8 and FIG. 9, the rollers 17 ₁ , 17 ₂ , 17 ₃ , 17 ₄ , 17 ₅ ,... Are sequentially moved from the upstream side to the downstream side in the running direction of the chain 5. The arrangement will be specifically described. Here, the total number of rollers is 17 _{1 to} 17 ₇ .

First, the arrangement of the third and subsequent rollers 17 ₃ , 17 ₄ , and 17 ₅ from the upstream end in the running direction of the chain 5 and the third and subsequent rollers from the downstream end will be described. For example, as shown in FIG. 8, third from the upstream end of the chain traveling direction rollers 17 ₃ (from the downstream end 5 th), the rollers 17 ₃ upstream two adjacent the side of the roller ₁₇ 1, 17 ₂ A regression circle R ₃ based on two rollers 17 ₄ and 17 ₅ adjacent to the downstream side is drawn, and this regression circle R ₃ is used as a reference circle. Regression circle _{R 3} is a disk, such as root mean square of the distance from the outer peripheral surface of the case four rollers _{17 1,} 17 _2, 17 4, 17 ₅ is minimized, the roller ₁₇ 1, ₁₇ 2, 17 _4, 17 can be obtained from the ₅ center position and radius.

Then, as shown in FIG. 10, the contact of the regression circle _{R 3} rollers 17 ₃ in the area radius is sandwiched between 1.0mm smaller circle than the regression circle _{R 3} and circle radius is larger 0.8mm than the chain 5 the point _{P 3} to place the rollers 17 ₃ to present. Rollers 17 ₃ and the contact point _{P 3} of the chain 5, the straight line _{L 3} connecting the centers of the roller 17 ₃ of the regression circle _{R 3} is an intersection intersecting the outer peripheral surface of the roller 17 _3. Other roller ₁₇ 4, 17 arranged in ₅ is also performed in the same manner.

Next, a description from the second roller 17 ₂ and the downstream end from the upstream end in the running direction of the chain 5 for the arrangement of the second roller 17 _6. For example, as shown in FIG. 9, the second roller 17 ₂ from the upstream end in the running direction of the chain 5, the fourth roller from the third roller 17 ₃ and the upstream end of the roller 17 ₁ and the upstream end of the upstream end 17 ₄ to draw the circumscribed circle _{R 2} in contact in common, use of the circumscribed circle _{R 2} as reference circle.

Then, as shown in FIG. 11, the contact of the circumscribed circle _R roller 17 ₂ to the region where the radius is sandwiched between 1.0mm smaller circle than the circumscribed circle _{R 2} radius and 0.8mm larger circle than ₂ and the chain 5 placing the roller 17 ₂ to the point _{P 2} is present. Roller 17 ₂ and the contact point _{P 2} of the chain 5 is the intersection of the straight line _{L 2} intersects the outer peripheral surface of the roller 17 ₂ connecting the center and the roller 17 ₂ of the center of the circumscribed circle _{R 2.} Disposed from the downstream end of the second roller 17 ₆ is also conducted in a similar manner.

  Next, an operation example of the chain transmission device configured as described above will be described.

  When the engine is operating, the chain 5 travels between the drive sprocket 2 and the driven sprocket 4, and torque is transmitted from the crankshaft 1 to the camshaft 3 by the chain 5. At this time, the swing-side chain guide 7 keeps the tension of the chain 5 constant by pressing the chain 5 with the urging force of the chain tensioner 8, and the fixed-side chain guide 9 is used to run the ideal chain 5. The vibration of the chain 5 is suppressed while keeping the line.

  Here, each roller 17 of the chain guides 7 and 9 rotates while contacting the back side edge of each frame constituting the chain 5, thereby rolling and guiding the chain 5. Here, since the contact between the chain 5 and the chain guides 7 and 9 is rolling contact, the running resistance of the chain 5 is small, and the torque transmission loss is small.

Incidentally, the contact point _{P 3} of the roller 17 ₃ and the chain 5 shown in FIG. 8, if, the upstream side and the downstream side each other rollers ₁₇ 1 adjacent _to, 17 _2, 17 4, 17 ₅ along drawn regression circle R If that is the arrangement shifted larger than 0.8mm on the outside with respect to _3, the load applied from the chain 5 to the roller 17 _3, from the chain 5 on the upstream side and the roller ₁₇ 2 adjacent to the downstream side, 17 ₄ becomes larger than such a load, the rollers 17 ₃ is damaged earlier than the other rollers 17 _2, 17 _4, chain guide 7 is can lead to life. Conversely regression, the contact point _{P 3} of the roller 17 ₃ and the chain 5 shown in FIG. 8, tentatively, drawn along the upstream side and the roller ₁₇ 1 adjacent to the downstream _side, 17 _2, 17 4, 17 ₅ circle if against R ₃ has a configuration which is shifted larger than 1.0mm on the inside, the load applied to the roller 17 ₃ shifted to the inside, upstream and downstream adjacent side rollers 17 _2, 17 _{As a result} , the load applied to the roller ₄ is increased, and one of the rollers 17 ₂ and 17 ₄ is damaged before the roller 17 ₃ , and the chain guide 7 reaches the end of its life.

In contrast, the chain guide 7 in this embodiment, the range is, the upstream side and the downstream adjacent side roller 17 _1, 17 ₂ in the presence of the contact point P ₃ of the roller 17 ₃ and the chain 5 shown in FIG. 8, 17 _4, 17 because ₅ than regression circle _{R 3} drawn along such within 0.8mm outside, the load applied from the chain 5 to the roller 17 _3, the roller ₁₇ 2 adjacent to the upstream side and the downstream side, 17 ₄ It is possible to prevent the load from becoming larger than the load. Moreover, the existence range of the contact point _{P 3} of the roller 17 ₃ and the chain 5 is from the upstream side and the downstream side each other rollers ₁₇ 1 adjacent _to, 17 _2, 17 4, 17 regression circle _{R 3} which are drawn along the ₅ also because within 1.0mm inwardly, the load applied from the chain 5 to the roller 17 _3, it is possible to prevent the load applied to the roller 17 _2, 17 ₄ adjacent to the upstream side and the downstream side is increased. As a result, the uniform load exerted on each roller ₁₇ 2-17 ₄ from the chain 5, to equalize the respective rollers ₁₇ 2-17 ₄ life, the life of the chain guide 7 can be extended as a whole.

Similarly, circumscribed circle R of the range of existence of contact points _{P 2} of the roller 17 ₂ and the chain 5 shown in FIG. 9, is drawn along the upstream and downstream adjacent side roller _{17 1,} 17 3, 17 ₄ since ₂ such within 0.8mm outside the, load applied from the chain 5 to the roller 17 _2, be prevented from becoming larger than according the load on the upstream side and the downstream side each other rollers 17 1 adjacent _to, 17 ₃ it can. Moreover, the range of existence of contact points _{P 2} of the roller 17 ₂ and the chain 5, the upstream side and the downstream adjacent side roller _{17 1,} 17 3, 17 on the inner side of the circumscribed circle _{R 2} which are drawn along the ₄ since within 1.0 mm, the load applied from the chain 5 to the roller 17 _2, it is possible to prevent the load applied to the roller 17 _1, 17 ₃ adjacent to the upstream side and the downstream side is increased. As a result, the load applied to each of the rollers 17 _{1 to} 17 ₃ from the chain 5 is made uniform, the life of each of the rollers 17 _{1 to} 17 ₃ is made uniform, and the life of the chain guide 7 can be extended as a whole.

  As described above, in the chain guide 7 of this embodiment, the contact point between each roller 17 and the chain 5 is 0.8 mm outside the reference circle drawn along the rollers 17 adjacent to the upstream side and the downstream side. Since each roller 17 is disposed so as to be within a range of 1.0 mm or less on the inner side, the load applied to each roller 17 from the chain 5 is made uniform, and a specific roller 17 is more than the other rollers 17. The short life can be prevented, and as a result, excellent durability is exhibited.

  As the chain 5 for transmitting the rotation of the crankshaft 1 to the camshaft 3, a silent chain, a roller chain, a bush chain in which a roller is omitted from the roller chain, and the like can be employed.

Second drive sprocket 4 driven sprocket 5 chain 6 fulcrum shaft 7 chain guide 8 chain tensioner 15 guide base 16 roller shaft 17 _{1, 17 2,} 17 _3, 17 4, 17 ₅ roller 22 outer ring _P 2, _{P 3} contact points R ₂ circumcircle R ₃ regression circle

Claims (6)

A guide base extending in the running direction of the chain that transmits the rotation of the crankshaft of the engine to the camshaft, a plurality of roller shafts attached to the guide base in an arc along the running direction of the chain, and each of the rollers A chain guide that is rotatably supported by a shaft and that guides the chain by rolling with each of the rollers.
The third and subsequent rollers from the upstream end in the chain running direction and the third and subsequent rollers from the downstream end are separated from the outer peripheral surfaces of the two rollers adjacent to the upstream side of the roller and the two rollers adjacent to the downstream side. It is arranged that the contact point between the roller and the chain exists within the range of 0.8 mm on the outer side and 1.0 mm on the inner side of the regression circle defined as the circle having the smallest mean square of distance. A featured chain guide. The second roller from the upstream end in the chain running direction is within 0.8mm outside the circumscribed circle that is in contact with the upstream roller, the third roller from the upstream end, and the fourth roller from the upstream end. the chain guide of claim 1 in which the contact point of the roller and the chain within a range of 1.0mm are arranged to be present. The second roller from the downstream end in the chain running direction is within 0.8 mm outside the circumscribed circle that is in common contact with the roller at the downstream end, the third roller from the downstream end, and the fourth roller from the downstream end. The chain guide according to claim 1 or 2 , wherein the roller guide and the chain contact point are located within a range of 1.0 mm or less . The guide base extends in the running direction of the chain and supports a pair of side plates that support both ends of each roller shaft, and a plurality of connections that are disposed between adjacent roller shafts to connect the pair of side plates. the chain guide according to any one of claims 1 to 3, and a part. A chain transmission device comprising a chain spanned between a drive sprocket and a driven sprocket, a swingable chain guide provided on the slack side of the chain, and a chain tensioner that presses the chain guide toward the chain In
A chain transmission device, wherein the chain guide is the chain guide according to any one of claims 1 to 4 . Further comprising, a chain transmission, according to claim 5 which is a chain guide according to any one the chain guide of claims 1 to 4, the fixing of the chain guide provided on the tight side of the chain.

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