FR2731486A1 - GUIDE RAIL IN PARTICULAR CHAIN TENSIONER FOR CAMSHAFT DRIVE OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

a) Guide rail, in particular chain tensioner for a camshaft drive of an internal combustion engine. B) Rail characterized in that the base body (12) has on its face turned towards the sliding lining (14), a U-shaped profile (16) seen in section, which receives the sliding lining (14) .

Description

I

  "Guide rail including chain tensioner for a

  camshaft drive of an internal combustion engine

dull

  The invention relates to a guide rail, in particular

  chain tensioner for a camshaft drive of an internal combustion engine, composed of a base body and a slip lining held by the

  basic body to guide a chain.

  State of the art There are known guide rails of this type. They serve to guide and stretch chains and other means

  for example, belts or similar means

  to drive camshafts or other equipment

  motor vehicle parts. Channels are trained

  by the internal combustion engine of the vehicle and transmits

  drive energy to the camshaft or

  ments. The guiding of the chain is of particular importance. Guiding must be done in such a way that the chain is at the tension necessary to transmit the motive power with a minimum of losses and to avoid

  any slippage between the training elements of

camber or equipment.

  For example, there is known such a chain tensioner according to DE 37 06 136. This consists of a base body and a sliding lining mounted in the base body. The slip liner is connected to the base body by extending dovetail links

in the direction of the chain.

Advantages of the invention

  The present invention relates to a guide rail

  chain linkage corresponding to the type defined above characterized in that the base body has on its face facing the sliding lining, a shaped profile

  U seen in section, which receives the sliding pad.

  The chain guide rail according to the invention offers the advantage of being of a simple and light construction

  and especially, especially in the case of a self-

  mobile, to operate reliably regardless of the operating conditions. As the base body surrounds the slip liner by a connection by the shape on at least three sides, one has a very

  stable and very compact which resists in a safe way

  the operating conditions that occur during

  the use of this guide rail under the conditions described

  finished. In particular, the slip lining is

  turned by the base body on at least three sides. This gives, in an extremely small footprint, a rail of

  very resistant to torsion guidance.

  According to an advantageous embodiment of the invention

  the base body has a U-shaped section receiving the slip lining also preferably having a U-shaped section. Thus, the branches of the U-shaped sections can support each other so well.

  that at the level of the lateral guide of the chain, one has a dou-

  wall for the guide rail. This results in a

  guide rail having a very high rigidity.

  According to another preferred embodiment of the invention, the branches of the sliding lining have radial projections coming into cavities of the U-shaped legs of the base body. Cavities have

  preferably a larger axial extension, in the di-

  circulation rection of the chain, as the protrusions of the sliding pad. It advantageously results that the engagement of the projections in the cavities ensures a good locking of the sliding lining. The weakest axial extension of the projections also ensures

  very advantageous, the compensation of the coefficients of

  different thermal conditions from the basic body and the

  slip-off because the sliding liner can slide longitudinally in the U-section of the base body. Thus, thanks to a different coefficient of thermal expansion or to a higher heating than the basic body, the lining can be lengthened without causing

  distortions in the realization of the guide rail.

  According to a preferred embodiment, the

  branches of the basic body are not continuous in the di-

  guiding rection of the chain. These branches preferably

  only where there are cavities. he

  This results in a weight gain for the entire guide rail.

  without the strength of the guide rail being

important cause.

  Drawings The present invention will be described hereinafter at

  with the help of examples of realization represented diagrammatically

  FIG. 1 is a perspective view of a chain tensioner; FIG. 2 is a longitudinal section of a FIG.

  chain tensioner corresponding to another embodiment of

tion,

  FIG. 3 is a sectional view along the line

I-I of Figure 2.

  Description of the embodiments

  FIG. 1 is a perspective view of a chain tensioner generally bearing the reference 10. The chain tensioner 10 is composed of a base body 12 and

  slip pad 14. To receive the

  14, the base body 12 has on its side

  A U-shaped profile 16. The branches 18 of the U-profile 16 surround the slip liner 14 by a shape connection. The slip liner 14 itself is

  also in the form of a U-shaped profile 20 whose branches

  22 are applied against the legs 18 of the U-profile 16. The U-shaped profiles 16 and 20 are arranged so that the open sides are rotated in the same direction. The base body 12 comprises a support frame 24 which is formed, in a manner not described in detail, by a number of spacers 26 giving the base body 12 the necessary strength. Inside the base body 12, there are two sleeves 28. These sleeves 28 serve to fix the

  chain tensioner 10 on a mechanical element which is not

  such as the internal combustion engine of a vehicle

  automobile, by passing suitable screws through

the sleeves 28.

  The branches 18 of the U-profile, 16 have steps

  wise in the form of spaced apart slots 30, extending into the

  chain direction 32. The passages 30 re-

  have radial projections 34 of the glide pad

  14. The protrusions 34 here (seen in the chain circulation direction 32) have a lower axial extension

  the passages 30. As a result, the projections 34 do not replace

  that a specific part of the passages 30

  a free interval 36 in the passages 30. Only one

  first projecting portion 34 'has an axial length cor-

  corresponding to that of passage 30; the passage then complete

  filled is bound by a bond by the form. The perspective view clearly shows that the U-profile 16 may have zones 38 in which the branches 18 are not continuous in the direction of flow of

chain 32.

  Both the base body 12 and the trim

  14 are usually made of synthetic material

  adapted to the respective requirements. The basic body 12

  may be of a synthetic (or plastic) material

  fiber giving the chain tensioner the necessary strength. The slip liner 14 is made of a wear-resistant plastic material and allows sliding with the least possible friction for the chain.

  When the chain tensioner 10 is put into operation

  1, a chain not shown is passed over the chain tensioner 10 in the direction of circulation 32. The chain then slides along the lining 14 which guides it both by its bottom (surface 42) and by its branches 22.

  longitudinal forces applied to the glide pad

  14 in the circulation direction 32 of the chain, are transmitted to the U-profile, 16 by the projecting portion 34 '; this avoids the sliding of the U-shaped profile 20 of the sliding member 14 which is surrounded on three sides, by a connection in the form, by the U-section, 16. The

  projecting portion 34 'is dimensioned to receive separately

  the maximum forces occurring in the longitudinal direction. During use, the chain tensioner 10 warms up normally. This heating may come on the one hand from the internal combustion engine of the vehicle and

  on the other hand frictional heat during sliding

  This results in a different expansion behavior between the slip liner 14 and the base body 12. This is because the base body 12 and the slip liner 14

  are made of different materials with different

  different thermal expansion ficients. In addition,

  The slip member 16 may be heated more strongly than the base body 12 by the heat of friction released by the chain. This different expansion results in a relative elongation of the liner 14 in the running direction 32 of the chain, relative to the base body 12. This expansion is not hindered by the base body 12 because the radial projections 34 housed In the passages 30 of the branches 18 have a certain clearance in the direction of circulation 32. The lining 14 can thus move by a length defined by the passages 30. As the sliding member 14 is blocked relative to the body base 12 at its projecting portion 34 ', this temperature rise results in an elongation in the direction of the end of the slip liner 14 opposite the protruding portion 34'. This possibility of dilatation

  free of the sliding member 14 avoids that constraints

  are not created between the base body 12 and the trim

  14. This does not limit the movement of

the chain.

  The zones 38 o the U-profile, 16 does not have branches 18, reduce overall the weight of the base body 12. The importance of the zones 38 is chosen to

  not reduce the blockage in the position of the sliding pad

14.

  Figure 2 shows a longitudinal section of another chain tensioner 10 for which the same parts as in Figure 1 have the same references despite a partly different construction. The sectional view clearly shows that the chain tensioner 10 has a curved shape;

  profiles U, 16 and 20 describe the predefined curved shape

  completed. Both the base body 12 and the sliding member 14 can be made in the form of an injected part or a part made to the press in the

  plastic material, which allows a relative shaping

simple operation.

  The longitudinal section shows in plan view a branch 22 of the U-shaped profile 20, that is to say of the sliding member 14. The sliding member 14 is surrounded by the U-profile 16 of the basic body 12; in the sectional view, only the bottom 40 of the U-profile 16 appears here. The

  spacers 26 arrive directly on the bottom 40 and form

  24. The sectional view shows the bottom 42 of the sliding member 14 extending over the entire length of the chain tensioner 10 with a connection by the form on

the bottom 40 of the U-profile, 16.

  At one end 44, the bottom 42 may be pro-

  10 O lined beyond the U-shaped profile, 20 and come for example in an arc of the bottom 40 of the U-profile, 16. The embodiment of the arc is that the sliding member 14 can slide in the direction of circulation 32 because a force acting in the longitudinal direction is transmitted by the arc to

basic body 12.

  Figure 2 further shows the protruding portions 34 which come into the passages 30. These protruding parts are shown in broken lines because they do not appear in the sectional view. It is clear that the passages 30 have, in the longitudinal direction of the

  chain tensioner 10, a length greater than the parts

  34. Thus, in the exemplary embodiment

  represented here, we also have a free mobility of the

  slip 14 under the effect of thermal expansion

  different from the basic body 12.

  FIG. 3 is a sectional view taken along the line II in FIG. 2. This sectional view shows, on the one hand, the U-profile 16 of the base body 12 and the U-profile 20 of the 14. The branch 18 of the U-profile, 16 or the branch 22 of the U-profile, and the

  bottom 40 and the bottom 42 of the U-profiles, 16, 20 are in con-

  tact by a form connection over the entire length. The or-

  The sliding frame 14 is thus surrounded on three sides by a shape connection by the U-profile 16 of the base body 12 and substantially receives this lining. In addition, this figure shows the arrangement of the protruding portions 34 in the passages 30. The projecting portions 34 have radially directed tapered flanks 48 which open outward at an angle E. The bearing surfaces 50 passages 30 also make an angle a. The angle results from the inclined surfaces of the injection mold; this angle is for example equal to 1. The taper of the protruding portions 34 and passages 30 is

  that the branches 20 of the sliding member 14 are

  bound together with the branches 18 of the basic body 12

  transversely to the direction of circulation.

  projects 34 come virtually behind the support surface 50 which prevents radial mobility

  22. Like passages 30 (this appears to be clear

  1 and 2) have a greater length than the protruding portions 34, despite the conicity of the

  flanks 48 or bearing surfaces 50, the sliding member

  14 can move in the direction of circulation 32.

  The chain tensioner 10 can be made of

  simple way in one piece for example by injecting

  tion. For this purpose, the base body 12 is first made in a suitable mold. Then the sliding member 14 is injected into the base body 12, in particular into the U-profile 16 of the base body 12, during a step

  following process, using a suitable mold. Pen

  the injection, the projecting parts 34 are made at the same time so that after the setting of the sliding member 14, it is placed as described above, in the

basic body 12.

Claims (4)

R E V E N D I C A T IONS   1) Guide rail including chain tensioner   for a camshaft drive of a combustion engine   internal arrangement, consisting of a base body and a sliding lining held by the base body for guiding a chain, characterized in that the base body (12)   present on its face turned towards the gliding pad-   (14), a U-shaped section (16) seen in section, which   receives the sliding pad (14).   2) Guide rail according to claim 1, characterized in that the sliding lining (14) has, in section, a U-shaped profile (20) whose branches (22) are applied against the branches (18) U-profile (16). 3) A guide rail according to claim 1, characterized in that the sliding member (14) and the base body (12) are relative sliding, at least by zone, in the direction of circulation (32) of chain. 4) Guide rail according to claim 3, characterized in that the legs (18) of the U-shaped profile (16) of the base body (12) have passages (30) extending in the direction of movement ( 32), passages into which projecting portions (34), radial, branches (22) of the U-shaped profile penetrate.   (12) of the slip liner (14).   Guide rail according to Claim 4, characterized in that the projections (34) have a smaller axial length than the passages (30).   in the traffic direction (32) of the chain.   6) Guide rail according to any one of   4 or 5, characterized in that in the di-   radial recess, the protruding portions (34) have conical flanks (48) in shape connection with surfaces   conical bearing (50) of the passages (30).   7) Guide rail according to any one of   claims 4, 5 or 6, characterized by at least one   protruding portion (34 ') whose axial length corresponds to the axial length of the passage (30) which receives this projecting portion. 8) Guide rail according to any one of   preceding claims, characterized in that the branches   of the U-profile (16) of the base body (12) are not continuous in the guiding direction (32) of the chain.