JP2013024313A - Chain guide and chain transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress abrasion of an outer diametrical surface of a chain guiding roller in a chain guide to attain a long working life.SOLUTION: Respective shaft end portions of a plurality of roller shafts 31 are supported by a pair of opposed side plates 22 of guide bases 21 which are oppositely disposed to one side of a torque transmission timing chain 5. Rollers 41 including a plurality of chain guiding roller bearings are rotatably supported by a plurality of roller shafts 31 respectively. A roller having a surface hardness greater by 4 points or more than that of the timing chain 5 in terms of Rockwell hardness is used as the roller 41, so that the outer diametrical surface of the roller 41 is prevented from being abraded in an early stage by the contact with the timing chain 5.

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.

  In the chain transmission device for driving the camshaft, in which the timing chain is spanned between the drive sprocket attached to the crankshaft and the driven sprocket attached to the camshaft, the chain can swing to one side of the slack side chain of the timing chain. A 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 Patent Document 1, both ends of a plurality of roller shafts arranged in a curved shape are supported by a guide base that extends in the moving direction of the timing chain. A chain guide is proposed in which a roller comprising a roller bearing is rotatably supported by each of the rollers, and the timing chain is supported by the plurality of rollers so as to be movable.

  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 the said patent document 1, nothing is mentioned about the surface hardness of the roller which guides the movement of a timing chain. If a roller whose surface hardness is lower than necessary is adopted, the outer diameter surface will be worn early due to contact with the timing chain moving at a high speed. Further, if the surface hardness of the roller is increased more than necessary in order to suppress the wear, the manufacture of the roller becomes difficult and the cost is increased, and cracks are likely to occur.

  An object of the present invention is to extend the life of the chain guide by suppressing wear on the outer diameter surface of the chain guide roller.

  In order to solve the above-described problem, in the chain guide according to the present invention, a guide base having a side plate portion that is disposed on a part of the outer periphery of the timing chain and extends long in the moving direction of the timing chain, and the guide base A plurality of roller shafts supported by a shaft support portion formed on the side plate portion and spaced apart in the length direction of the side plate portion, and a chain rotatably supported on each of the plurality of roller shafts In the chain guide composed of a plurality of guide rollers, a configuration is adopted in which the surface hardness of the roller is set to 4 or more points in terms of Rockwell hardness with respect to the surface hardness of the timing chain.

  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.

  In the chain guide according to the present invention, as described above, the wear of the outer surface of the roller is suppressed by making the surface hardness of the roller at least 4 points in terms of Rockwell hardness with respect to the surface hardness of the timing chain. be able to.

  Here, the timing chain includes a roller chain and a silent chain. In these timing chains, since the surface hardness of the plate that is flexibly connected by the pin is about HRC 50 to 54 in terms of Rockwell hardness, the surface hardness of the roller should be HRC 58 or higher in terms of Rockwell hardness. Is preferred.

  If the Rockwell hardness is higher than necessary, the manufacture of the roller becomes difficult and the cost is increased, and the toughness is reduced and the cracks are liable to occur. Therefore, the surface hardness of the roller is the Rockwell hardness. HRC64 or less is preferable.

  When forming a roller with high surface hardness as described above, high carbon steel is used as the roller material, and after forming the roller, induction hardening or bright quenching is used, or low carbon steel is used as the roller material, and after forming the roller A processing method of carburizing and quenching or carbonitriding and quenching can be employed.

  By adopting a needle roller bearing or a cylindrical roller bearing having an outer ring and a plurality of rollers incorporated inside as the roller, the roller can be smoothly rotated by contact with the chain, and the movement resistance of the chain can be reduced. It can be greatly reduced.

  In the present invention, as described above, the surface hardness of the roller is set at 4 points or more in terms of Rockwell hardness with respect to the surface hardness of the chain, thereby suppressing wear on the outer surface of the roller and extending the service life. Can be planned.

Schematic showing the embodiment of the chain transmission according to the present invention The perspective view of the chain guide which concerns on this invention 2 is a longitudinal sectional view Right side view of FIG. Sectional view along line VV in FIG. Cross section of the roller shown in FIG. Exploded front view showing part of guide base and rollers Sectional view showing another example of needle 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, between a drive sprocket 2 attached to the end of a crankshaft 1 and a driven sprocket 4 attached to each of the ends of two camshafts 3. The timing chain 5 is spanned.

  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 moves the timing chain 5 in the direction indicated by the arrow in the figure, and the part from the drive sprocket 2 to one driven sprocket 4 located on the left side in the figure is the slack side, is a moiety tight side extending from the driven sprocket 4 to the drive sprocket 2, the 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 14 projecting from the engine block, and can swing about the fulcrum shaft 14. An adjustment force of the chain tensioner 15 is applied to the swing side end portion 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 in the same manner as the swingable chain guide A _1, and both ends thereof are fixed by tightening bolts 16 screwed into the engine block. It is supposed to guide the movement of.

Here, the pivotable chain guide A ₁ and the fixed chain guide A _2, is the same configuration, pivotable chain guide A ₁ is an insertion hole for the shaft inserted into one end portion is formed whereas, chain guide a ₂ fixed is only different in that the insertion hole for the bolt inserted into both end portions are formed.

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 14 is inserted is formed at the upper end portion thereof.

  A plurality of bearing recesses 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 at intervals in the length direction of the side plate portion 22.

  As shown in FIG. 7, the bearing recess 25 has a tapered groove portion 25 a that faces in 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, and the opening end of the outer surface portion is wide. , And a circular concave portion 25b as a shaft support portion communicating with the narrow end of the tapered groove portion 25a. The roller shaft 31 is fitted into the circular recess 25b from the taper groove 25a, and is supported by the circular recess 25b.

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 recess 25b from the taper groove 25a, and is fitted and supported with a tightening margin in the circular recess 25b.

  The plurality of bearing recesses 25 have an arcuate arrangement in which a line connecting the centers of the circular recesses 25b draws a convex arcuate line, but may be a curved arrangement.

  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.

  The guide base 21 may be cast using a light metal such as an aluminum alloy or a magnesium alloy, or may be die-cast.

  The plurality of roller shafts 31 are fitted in each of the plurality of bearing recesses 25. The roller shaft 31 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 and quenching may be performed.

  The plurality of rollers 41 are rotatably supported by each of the plurality of roller shafts 31. As shown in FIG. 6, a needle roller bearing is employed here as the roller 41. The needle roller bearing 41 includes an outer ring 42, a plurality of needle rollers 43 incorporated inside the outer ring 42, and a cage 44 that holds the needle rollers 43.

  The outer ring 42 is made of a low carbon steel such as SPC or SCM, is formed by drawing and is formed into a shell shape, is hardened by heat treatment, and has a surface height of about HRC 58 to 74. As the heat treatment, carburizing quenching or carbonitriding quenching can be employed. Alternatively, bright quenching or induction quenching can be employed using high carbon steel such as SUJ2 or SC material.

  The outer ring 42 has a surface hardness of 4 points or more according to the hardness of the timing chain 5 employed in the chain transmission.

  The outer ring 42 may be formed by cutting. Further, a cylindrical roller bearing may be employed instead of the needle roller bearing. The needle roller bearing and the cylindrical roller bearing 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 15 prevents looseness and fluttering.

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

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

Each of the plurality of rollers 41 of the chain guide A ₁ and the fixed chain guide A ₂ is rotated by contact with the timing chain 5 as described above, and the roller 41 having a surface hardness lower than necessary is employed. Then, contact with the timing chain 5 that moves at a high speed causes the outer diameter surface to wear early, resulting in a problem in durability.

  However, in the embodiment, as the roller 41, the roller 41 whose surface hardness is hardened by 4 points or more in terms of Rockwell hardness with respect to the surface hardness of the timing chain 5 is adopted. However, there is no inconvenience of early wear due to contact with the timing chain 5, and wear of the outer diameter surface of the roller 41 can be suppressed to extend the life.

  FIG. 8 shows another example of the roller 41. In this example, a separate outer cylinder 50 is press-fitted into the outer diameter surface of the shell-shaped outer ring 42 of the needle roller bearing, and the movement of the timing chain 5 is guided by the outer cylinder 50.

  In this case, the outer cylindrical body 50 is formed of steel such as SUJ2 or SCM, and is hardened by heat treatment so that the surface hardness is about HRC58 to 64, and the surface hardness is Rockwell hardness according to the hardness of the timing chain 5. Now, try to use 4 or more points.

A ₁ Chain guide A ₂ Chain guide 2 Drive sprocket 4 Driven sprocket 5 Timing chain (chain)
21 Guide base 22 Side plate portion 31 Roller shaft 41 Roller (Needle roller bearing)
42 outer ring 43 needle roller

Claims (7)

A guide base that is disposed on a part of the outer periphery of the timing chain and has a side plate portion that extends long in the moving direction of the timing chain, and a shaft support portion that is formed on the side plate portion of the guide base. In a chain guide comprising a plurality of roller shafts provided at intervals in the length direction, and a plurality of chain guide rollers rotatably supported on each of the plurality of roller shafts,
A chain guide characterized in that the roller has a surface hardness of at least 4 points in terms of Rockwell hardness relative to the surface hardness of the timing chain.   The chain guide according to claim 1, wherein the roller has a surface hardness of HRC64 or less in terms of Rockwell hardness.   The chain guide according to claim 1, wherein the roller is made of a heat-treated steel product.   The chain guide according to claim 3, wherein the heat treatment is one of bright quenching, induction quenching, carburizing quenching, and carbonitriding quenching.   The chain guide according to any one of claims 1 to 4, wherein the roller comprises a roller bearing having an outer ring and a plurality of rollers incorporated therein. 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 5.   6. A chain guide for guiding the movement of the timing chain is provided on one side of the tension chain of the timing chain so that the chain guide is fixed, and the chain guide is a chain guide according to any one of claims 1 to 5. The chain transmission device according to claim 6.

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