JP2014020438A - Chain guide and chain transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain guide capable of molding a guide base excellent in durability, in the chain guide which performs rolling guide of the movement of a timing chain by means of a roller supported freely rotatably by the guide base.SOLUTION: A plurality of bearing parts 25 are disposed on lateral plate parts 22 of a pair of opposed guide bases 21 which are oppositely arranged on one side part of a timing chain 5 for torque transition and are molded with a mold, and shaft edge parts of the roller shaft 31 are supported on each of bearing parts 25. A roller 41 for guiding the chain is freely rotatably supported by each of a plurality of roller shafts 31. A parting line L is disposed between two intersection points a, b where a straight line A in the diameter direction which passes through the center of a circular inner surface of the bearing parts 25 elongated in the width direction of the lateral plate part 22 and the circular inner surface of the bearing parts 25 intersect each other, thus, it is prevented that a stress is concentrated on the parting line L.

Description

  The present invention relates to a chain guide used for adjusting the tension of a chain or for guiding movement of a chain, and a chain transmission using the chain guide.

  The camshaft drive chain transmission with a timing chain spanned between the drive sprocket attached to the crankshaft and the driven sprocket attached to the camshaft can swing to one side of the slack side chain of the timing chain A chain guide is provided, and the adjustment force of the chain tensioner is applied to the swing side end of the chain guide to tension the timing chain to prevent the chain from loosening and fluttering.

  Further, a chain guide is fixed to the tight chain of the timing chain, and the movement of the timing chain is guided by the fixed chain guide to suppress the fluttering.

  Here, as a chain guide for adjusting the tension of the timing chain or moving guide, there is known a type that guides the surface of the timing chain by sliding contact, but the timing chain has a large moving resistance and a lot of transmission torque crosses. There's a problem.

  In order to solve such a problem, in the present applicant, in Patent Document 1, both ends of a plurality of roller shafts arranged in a curved shape by a synthetic resin guide base extending long in the moving direction of the timing chain are described. A chain guide has been proposed in which a roller comprising a roller bearing is rotatably supported by each of the plurality of roller shafts, and the timing chain is guided by the plurality of rollers in a movable manner.

  The above-described chain guide is characterized in that the timing chain is guided by rolling of a plurality of rollers, so that the movement resistance of the timing chain is small and the transmission torque cross is small.

International Publication No. 2010/090139

  By the way, in the chain guide described in Patent Document 1, since the guide base is a molded product made of synthetic resin, a parting line can be formed on the pair of opposed side plates of the guide base.

  In Patent Document 1, nothing is mentioned about the parting line. In the guide base described in Patent Document 1, a plurality of column portions for adjusting the interval are formed between the pair of opposed side plate portions at intervals in the length direction of the side plate portion. The opening direction is a direction intersecting the length direction of the side plate portion, and a parting line is formed on the opposing inner surface of the side plate portion.

  In this case, when the parting line is formed in the load application region, stress concentrates on the parting line and the guide base is easily damaged, resulting in a problem in durability.

  Here, the load load area refers to a portion that receives a load applied to the roller and the roller shaft from the timing chain, and a portion between the through hole and the side surface of the guide base is a load load area.

  An object of the present invention is to make it possible to form a guide base having excellent durability in a chain guide that rolls and guides the movement of a timing chain by a roller rotatably supported by the guide base.

  In order to solve the above-described problems, in the chain guide according to the present invention, a mold having a pair of opposed side plates that are arranged on a part of the outer periphery of the timing chain and extend long in the moving direction of the timing chain is formed. A guide base, a plurality of roller shafts having shaft end portions fitted into a circular bearing portion formed on the side plate portion, and spaced apart in the length direction of the side plate portion, and the plurality of rollers In a chain guide composed of a plurality of chain guide rollers rotatably supported on each of the shafts, a radial straight line extending in the width direction of the side plate portion through the center of the circular inner surface of the bearing portion and the bearing portion A configuration in which a parting line is installed between two intersecting points where the circular inner surface of each other intersects is adopted.

  Further, in the chain transmission device according to the present invention, the swingable chain that guides the movement of the timing chain over one side of the slack side chain of the timing chain, spanning the timing chain between the drive sprocket and the driven sprocket. In the chain transmission device in which a guide is provided, the adjustment force of the chain tensioner is applied to the swing side end portion of the chain guide, and the swing side end portion is pressed against the timing chain. The above-described chain guide is adopted.

  In the chain transmission device configured as described above, a fixed chain guide for guiding the movement of the timing chain is provided on one side of the tight chain of the timing chain, and the chain guide according to the present invention is used as the fixed chain guide. By adopting, the flutter of the timing chain can be effectively suppressed.

  Here, when the movement of the timing chain is guided by the plurality of rollers, the pressing force from the timing chain is applied to the roller and the roller shaft that supports the roller. The pressing force is received between the side surfaces of the bearing portion and the side plate portion, and the load load area is set between the bearing portion and the side surface of the side plate portion. In the guide base for molding the chain guide according to the present invention, since the parting line is installed so as to avoid the load load region, stress does not concentrate on the parting line.

  As a result, a guide base with sufficient strength and excellent durability can be obtained by molding.

  Here, if the parting line is installed at a position passing through the center of the circular inner surface of the bearing portion, the parting line can be furthest away from the load-loading region, so that a guide base with superior durability can be obtained.

  In the chain guide according to the present invention, if a protruding portion is provided around the inner bearing portion of the side plate portion, the protruding portion can prevent the roller end surface from rotating in contact with the parting line. In addition, wear and peeling of the parting line can be prevented.

  The guide base may be a synthetic resin injection-molded product or a light metal die-cast product. When a synthetic resin injection molded product is used, the roller shaft may be insert molded.

  In the chain guide according to the present invention, when a roller bearing with a seal having a seal at both ends as a roller and forming a gap between the inner diameter of the seal and the outer diameter surface of the roller shaft is used, Since the roller can be smoothly rotated by this contact, the movement resistance of the timing chain is small and the transmission torque cross can be reduced.

  Here, in the chain guide, the oil flows out from the oil outlet of the lubrication device provided in the engine and is scattered, or the oil supplied to the oil supply type chain tensioner is discharged from the tip of the tensioner and scattered. The roller bearing is lubricated by the scattered oil adhering to the outer ring of the bearing and the outer diameter surface of the roller shaft. If foreign matter is mixed in the lubrication oil, the roller bearing will be damaged by the biting of the foreign matter. There are cases. However, as described above, by using a roller bearing with a seal having a gap between the outer diameter surfaces of the roller shaft, it is possible to prevent damage due to the biting of foreign matter.

  In the present invention, as described above, the parting line is installed between two intersections where the radial straight line extending in the width direction of the side plate portion through the center of the circular inner surface of the bearing portion and the circular inner surface of the bearing portion intersect. As a result, the parting line can be removed from the load application range, and a sufficiently strong and durable guide base can be obtained.

Schematic showing the embodiment of the chain transmission according to the present invention 1 is a longitudinal sectional view of the chain guide shown in FIG. Sectional view along line III-III in FIG. Sectional view along line IV-IV in FIG. Longitudinal section of guide base Sectional view showing another example of guide base Sectional drawing along the VII-VII line of FIG. Sectional view showing still another example of guide base Sectional view along line IX-IX in FIG. Sectional view showing another example of roller bearing

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a chain transmission for driving a camshaft, and a timing chain is provided between a drive sprocket 2 attached to the shaft end of the crankshaft 1 and a driven sprocket 4 attached to each shaft end of the camshaft 3. 5 is hung.

  The timing chain 5 may be a roller chain or a silent chain.

The crankshaft 1 rotates in the direction indicated by the arrow in FIG. The rotation of the crankshaft 1 causes the timing chain 5 to move in the direction indicated by the arrow in the figure, the portion moving upward is a slack side chain 5a, and the portion moving downward is a tension side chain 5b. is a chain guide a ₁ is provided on one side of the slack side chain 5a.

The chain guide A ₁ extends long in the moving direction of the timing chain 5, and its upper end is supported by a fulcrum shaft 10 protruding from the engine block, and can swing around the fulcrum shaft 10. The adjustment force of the chain tensioner 11 is applied to the swing side end and is pressed toward the slack side chain 5a.

A chain guide A ₂ is provided on the other side of the tension chain 5 b in the timing chain 5. The chain guide A ₂ extends in the moving direction of the timing chain 5 similarly to the swingable chain guide A _1, and both ends thereof are fixed by tightening bolts 12 screwed into the engine block. It is supposed to guide the movement of.

Here, the swingable chain guide A ₁ and the fixed chain guide A ₂ have substantially the same structure, and the swingable chain guide A ₁ has an insertion hole for inserting a shaft at one end. while there, that chain guide a ₂ fixed insertion hole for bolt insertion at both ends are formed is different.

Therefore, here, is described below the structure of the pivotable chain guide A _1, the chain guide A ₂ of the fastening arrangement will be omitted with the same reference numerals to the same parts.

As shown in FIGS. 2 to 4, the chain guide A ₁ includes a guide base 21 extending long in the moving direction of the timing chain 5 and a plurality of roller shafts provided at intervals in the length direction of the guide base 21. 31 and a plurality of chain guide rollers 41 rotatably supported on each of the plurality of roller shafts 31.

  The guide base 21 has a configuration in which a plurality of interval holding plates 23 are formed at intervals in the length direction between a pair of opposed side plate portions 22. The pair of side plate portions 22 has a bow shape, and an insertion hole 24 into which the fulcrum shaft 10 is inserted is formed at the upper end portion thereof.

  In addition, a plurality of bearing portions 25 that support the shaft end portion of the roller shaft 31 are formed on the opposing inner surfaces of the pair of side plate portions 22 with a curved arrangement at intervals in the length direction of the side plate portions 22. Yes.

  The bearing portion 25 is formed of a through-hole penetrating both side surfaces of the side plate portion 22, and the roller shaft 31 is supported by being press-fitted into the bearing portion 25 and having an end surface exposed to the outside.

  The guide base 21 configured as described above is a synthetic resin molded product. It is preferable to use a resin excellent in oil resistance, weather resistance and strength as a synthetic resin. Examples of such a resin include polyamide 46 (PA46) and polyamide 66 (PA66). In order to further improve the mechanical strength, it is preferable to mix reinforced glass fibers in these resins.

  As shown in FIGS. 3 and 4, the roller shaft 31 has a straight shape and is made of SUJ2 or SC material. The roller shaft 31 is heat treated to increase its hardness in order to improve wear resistance. Here, bright quenching is employed as the heat treatment, but induction quenching or carburizing quenching may be performed. Alternatively, carbonitriding may be performed.

  The plurality of rollers 41 are rotatably supported by each of the plurality of roller shafts 31. Here, a roller bearing is employed as the roller 41. The roller bearing 41 includes an outer ring 42, a plurality of rollers 43 incorporated inside the outer ring 42, and a cage 44 that holds the rollers 43.

  The outer ring 42 is a shell shape obtained by drawing a metal plate such as SPC or SCM, and the hardness is increased by heat treatment. At both ends of the shell-shaped outer ring 42, inward flanges 45 that prevent the retainer 44 from being pulled out are formed. The inward flange 45 is bent after the cage 44 for holding the rollers 43 is assembled in order to facilitate the assembly of the roller bearing 41.

  The roller bearing 41 may be a needle roller bearing or a cylindrical roller bearing. The roller bearing 41 may be of a full roller type without a cage.

  The chain transmission shown in the embodiment has the above-described structure, and in a torque transmission state in which the rotation of the crankshaft 1 is transmitted to the camshaft 3 by the movement of the timing chain 5 spanned between the driving sprocket 2 and the driven sprocket 4. When the tension of the timing chain 5 changes due to a change in load, the chain tensioner 11 operates to absorb the tension change. For this reason, the timing chain 5 is always maintained in a predetermined tension state.

During torque transmission for transmitting the rotation of the crank shaft 1 to the camshaft 3, the roller 41 consisting of a roller bearing provided on each of the pivotable chain guide A ₁ and the fixed chain guide A ₂ is in contact with the timing chain 5 And the timing chain 5 is guided to roll.

  Thus, since the timing chain 5 is guided by the rolling of the roller 41, wear at the guide portion is small. In addition, the movement resistance of the timing chain 5 is small, the timing chain 5 moves smoothly, and torque is transmitted without loss.

  Here, in the roller 41 for guiding the timing chain 5, the outer ring 42 rotates at a high speed by contact with the timing chain 5, and the roller 43 rolls on the outer diameter surface of the roller shaft 31 while rotating. The roller shaft 31 is likely to become hot due to contact with the roller 43.

  At this time, as shown in FIG. 3, the bearing portion 25 to which the shaft end portion of the roller shaft 31 is fitted and supported is formed of a through hole, and the shaft end portion of the roller shaft 31 is press-fitted into the bearing portion 25 and the shaft end surface. Is exposed to the outside, the roller shaft 31 is prevented from becoming hot due to heat radiation from the shaft end face. For this reason, there is no inconvenience that the side plate portion 22 of the guide base 21 made of a synthetic resin molded product becomes hot due to heat conduction from the roller shaft 31 and the strength is lowered.

  Here, since the guide base 21 is a molded product of synthetic resin, it is inevitable that a parting line is formed on the pair of opposing side plate portions 22 of the guide base 21.

  The guide base 21 shown in the embodiment has a configuration in which a plurality of interval holding plates 23 are formed at intervals in the length direction between a pair of opposed side plate portions 22, so that the mold opening direction of the molding die Is a direction intersecting the length direction of the side plate portion 22, and a parting line is formed on the opposing inner surface of the side plate portion 22.

  In this case, when the parting line is formed in the load application region, stress concentrates on the parting line and the guide base is easily damaged, resulting in a problem in durability.

  Here, the load load area refers to a portion that receives a load applied to the roller 41 and the roller shaft 31 from the timing chain 5, and a portion indicated by a two-dot chain line a in FIG. 4 is the load load area.

  In the embodiment, in order to avoid the formation of a parting line in the load-loading area A, the diameter extending in the width direction of the side plate portion 22 through the center O of the circular inner surface of the bearing portion 25 as shown in FIG. When two intersections where the direction straight line A and the circular inner surface of the bearing portion 25 intersect are a and b, a parting line L is provided between the intersection a and the intersection b. In the embodiment, the parting line L is installed between the intersection point a and the intersection point b at a position passing through the center O of the bearing portion 25 that is the farthest from the load area B.

  As described above, by installing the parting line L between the intersection point a and the intersection point b, it is possible to remove the parting line L from the load application area A. Therefore, no stress is concentrated on the parting line L, and the strength is not reduced. For this reason, the guide base 21 with sufficient strength and excellent durability can be obtained by resin molding.

  In the embodiment, the guide base 21 is a synthetic resin molded product, but may be die-cast using a light metal such as an aluminum alloy or a magnesium alloy. In addition, when it is set as the injection molding product of a synthetic resin, you may insert-mold the roller shaft 31 which supports the roller bearing 41. FIG.

  As shown in FIG. 6 and FIG. 7, when a pair of protrusions 26 are provided at symmetrical positions around the bearing portion 25 on the inner surface of the side plate portion 22 with the parting line L as a symmetry line, The end surface of the outer ring 42 of the bearing 41 can be prevented from rotating in contact with the parting line L, and the wear and separation of the parting line L can be prevented.

  3 and 6, the bearing portion 25 is a through hole, but the bearing portion 25 is not limited to the through hole. 8 and 9 show another example of the bearing portion 25. In the bearing portion 25 shown in this example, a taper groove portion 25a in which the opening end of the side surface portion 22 faces the width direction of the side plate portion 22 from the outer surface portion facing the timing chain 5 of the side plate portion 22 is widened, and It consists of a circular recess 25b communicating with the narrow end of the taper groove 25a.

Here, _{D 1} the width of the narrow portion of the tapered groove 25a, the inner diameter of _{D 2} of the circular recess 25b, when the outer diameter of the roller shaft 31 is d, and the dimensional relationship of the relationship of _d> D 2> _{D 1} is satisfied The roller shaft 31 is pushed into the circular concave portion 25b from the tapered groove portion 25a, is used as a fitting support having a tightening margin in the circular concave portion 25b, and is prevented by the narrow portion of the tapered groove portion 25a.

  The roller bearing 41 that rolls and guides the timing chain 5 is lubricated by scattered oil that flows out from an oil outlet of a lubrication device provided in the engine or scattered oil that flows out from the tip of an oil supply type chain tensioner. At this time, if foreign matter is mixed in the oil, the foreign matter may enter the roller bearing 41, and the roller bearing 41 may be damaged by the biting of the foreign matter.

  Therefore, as shown in FIG. 10, if a roller bearing 41 with a seal in which a seal 46 for preventing entry of foreign matter is incorporated in the open end of the outer ring 42, foreign matter can be prevented from entering. It is possible to prevent the roller bearing 41 from being damaged, and to suppress a decrease in durability.

  In the use of the roller bearing 41 with the seal as described above, if the inner diameter portion of the seal 46 is in elastic contact with the outer diameter surface of the roller shaft 31, it becomes impossible to take lubricating oil into the outer ring 42. The inner diameter of the seal 46 is made slightly larger than the outer diameter of the roller shaft 31 so that a gap 47 is formed between the inner diameter surface of 46 and the roller rolling surface of the roller shaft 31.

A ₁ chain guide A ₂ chain guide 2 drive sprocket 4 driven sprocket 5 timing chain 21 guide base 22 side plate portion 25 bearing portion 31 roller shaft 41 roller bearing (roller)
46 Seal 47 Clearance L Parting line

Claims (9)

A guide base formed by molding having a pair of opposed side plate portions that are disposed on a part of the outer periphery of the timing chain and extend long in the moving direction of the timing chain, and a shaft end on a circular bearing portion formed on the side plate portion A plurality of roller shafts fitted to each other and spaced apart in the length direction of the side plate portion, and a plurality of chain guide rollers rotatably supported on each of the plurality of roller shafts, In the chain guide consisting of
A chain guide characterized in that a parting line is installed between two intersections where a radial straight line extending in the width direction of the side plate portion through the center of the circular inner surface of the bearing portion and the circular inner surface of the bearing portion intersect. .   The chain guide according to claim 1, wherein the parting line is a position passing through a center of a circular inner surface of the bearing portion.   The chain guide according to claim 1, wherein a protrusion that prevents the roller from rotating in contact with the inner surface of the side plate portion is provided around the bearing portion on the inner surface of the side plate portion.   The chain guide according to any one of claims 1 to 3, wherein the molding material is made of a synthetic resin.   The chain guide according to claim 4, wherein the roller shaft is insert-molded.   The chain guide according to any one of claims 1 to 3, wherein the molding material is made of a light metal.   7. The roller according to claim 1, comprising a roller bearing with a seal having a seal at both ends and forming a gap between the inner diameter of the seal and the outer diameter surface of the roller shaft. Chain guide. A timing chain is placed between the drive sprocket and the driven sprocket, and a swingable chain guide is provided on one side of the slack side chain of the timing chain to guide the movement of the timing chain. In the chain transmission device, the adjustment force of the chain tensioner is applied to the part, and the swing side end is pressed against the timing chain.
A chain transmission device, wherein the chain guide comprises the chain guide according to any one of claims 1 to 7.   A fixed chain guide for guiding the movement of the timing chain is provided on one side of the tight chain of the timing chain, and the fixed chain guide is formed of the chain guide according to any one of claims 1 to 7. The chain transmission according to claim 8.

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