Chain drive assembly with tensioning-rail mounting aid

Abstract

A chain drive assembly for an internal combustion engine comprises a tensioning rail supportable on an engine block so as to be pivotable about a pivot bearing axle and further comprises a pivot bearing that can be provided on the engine block. The tensioning rail having a projection, which protrudes from the tensioning rail relative to the support body, so as to hold, at least during mounting, the tensioning rail at a mounting position. Additionally, the invention relates to the use of such a tensioning rail for mounting on the engine block of an internal combustion engine as well as to a bipartite chain drive of an internal combustion engine and a suitable mounting method.

Claims

1. A chain drive assembly for an internal combustion engine, comprising a tensioning rail pivotable supportable about a pivot bearing axle on an engine block and further comprising a pivot bearing that can be provided on the engine block, said tensioning rail having a support body and a sliding-contact surface for contacting a driving chain, wherein the tensioning rail comprises at least one projection arranged on the support body of the tensioning rail and protruding in the direction of the engine block relative to said support body, wherein the at least one projection is arrangable in an assembly opening on the engine block so as to hold, at least while the tensioning rail is being mounted on the engine block, the tensioning rail at a mounting position relative to the engine block.

2. The chain drive assembly according to claim 1, wherein the at least one projection is a cylindrical projection, which is arranged concentrically around the pivot bearing axle.

3. The chain drive assembly according to claim 2, wherein the cylindrical projection is formed integrally with the support body.

4. The chain drive assembly according to claim 2, wherein the assembly opening on the engine block is configured as a pivot bearing opening and the cylindrical projection is configured as a pivot bearing bolt, the cylindrical projection being pivotably supported in the assembly opening so as to define the pivot bearing.

5. The chain drive assembly according to claim 1, wherein the at least one projection includes a pivot bearing opening, and that a pivot bearing bolt is provided, which is extendable through the pivot bearing opening so as to define the pivot bearing.

6. The chain drive assembly according to claim 1, wherein, in addition to the first tensioning rail, a second tensioning rail is provided, said second tensioning rail being supported such that it is pivotable about the pivot bearing axle of the pivot bearing, wherein the first tensioning rail has provided thereon, on the side of the support body located opposite the at least one projection, at least one holding element for holding the second tensioning rail at a mounting position on the first tensioning rail while the second tensioning rail is being mounted on the first tensioning rail.

7. The chain drive assembly according to claim 6, wherein the at least one holding element is configured as a stop projection protruding on the support body of the first tensioning rail in the direction of the second tensioning rail relative to the support body.

8. The use of a tensioning rail for mounting on an engine block of a internal combustion engine, with at least one projection arranged on a support body of the tensioning rail and protruding in the direction of the engine block relative to the support body, wherein the at least one projection is inserted into an assembly opening on the engine block so as to hold the tensioning rail at a mounting position.

9. The use of a tensioning rail according to claim 8, wherein the at least one projection is a cylindrical projection, which is arranged concentrically around the pivot bearing axle and which is inserted into a cylindrically formed assembly opening on the engine block so as to hold the tensioning rail at a mounting position.

10. The use of the first tensioning rail according to claim 8 and of a second tensioning rail for mounting a bipartite chain drive on the engine block, wherein the first tensioning rail has provided thereon, on the side of the support body located opposite the at least one projection, at least one holding element, and the second tensioning rail rests on the holding element of the first tensioning rail at a mounting position, so as to fix the second tensioning rail simultaneously with the first tensioning rail on the engine block.

11. A mounting method for a bipartite chain drive of an internal combustion engine, comprising a first tensioning rail and a second tensioning rail, which are supported so as to be pivotable about a pivot bearing axle of a pivot bearing provided on the engine block, wherein the engine block has provided thereon an assembly opening, the first tensioning rail includes at least one projection protruding in the direction of the engine block relative to the support body of the first tensioning rail, and said first tensioning rail additionally includes at least one holding element provided on the side of the support body located opposite the at least one projection, said mounting method comprising the following steps: arranging the at least one projection of the first tensioning rail in the assembly opening on the engine block; positioning the driving chain of the first chain drive along the first tensioning rail; arranging the second tensioning rail on the at least one holding element of the first tensioning rail; orienting the pivot bearing openings of the first and second tensioning rails concentrically with the pivot bearing axle; inserting the bearing bolt into the bearing openings of the first and second tensioning rails; and fixing the bearing bolt in position in the engine block.

12. The mounting method for a bipartite chain drive according to claim 11, wherein the at least one projection is a cylindrical projection which is arranged concentrically around the pivot bearing axle, and that the assembly opening is a cylindrical assembly opening formed concentrically with the pivot bearing axle.

13. A bipartite chain drive for an internal combustion engine, comprising a first tensioning rail and a second tensioning rail, said first tensioning rail and said second tensioning rail being adapted to be supported such that they are pivotable about a pivot bearing axle of a pivot bearing provided on the engine block of the internal combustion engine, wherein the first tensioning rail comprises a cylindrical projection which is arranged concentrically around the pivot bearing axle and which projects in the direction of the engine block relative to the support body of the first tensioning rail, wherein the cylindrical projection is adapted to be accommodated in an assembly opening on the engine block so as to hold the first tensioning rail at a mounting position while said first tensioning rail is being mounted on the engine block, and wherein the first tensioning rail has provided thereon, on the side of the support body located opposite the cylindrical projection, at least one holding element so as to hold the second tensioning rail at a mounting position on the first tensioning rail while said second tensioning rail is being mounted on the engine block.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, an embodiment of the present invention will be explained in more detail making reference to the enclosed drawings, in which:

(2) FIG. 1 shows a perspective view of a tensioning rail of a chain drive assembly according to the present invention,

(3) FIG. 2 shows a perspective view of the tensioning rail according to FIG. 1, arranged on the engine block,

(4) FIG. 3 shows a perspective top view of a chain drive assembly according to the present invention, in a first mounting step,

(5) FIG. 4 shows a perspective top view of the chain drive assembly according to the present invention as shown in FIG. 3, in a second mounting step,

(6) FIG. 5 shows a perspective top view of the chain drive assembly according to the present invention as shown in FIG. 3, in a third mounting step, and

(7) FIG. 6 shows a perspective top view of the chain drive assembly according to the present invention as shown in FIG. 3, in a fourth mounting step.

DETAILED DESCRIPTION

(8) The chain drive assembly 1 shown in FIG. 1 comprises a tensioning rail 2 with a cylindrical projection 5 protruding from the support body 3 of the tensioning rail 2 in the direction of the engine block 4 and a cylindrical assembly opening 6 formed in the engine block 4 and used for receiving therein the cylindrical projection 5. The support body 3 of the tensioning rail 2 has, on the visible upper surface and on the back (not shown), a plurality of truss members 7 for stiffening the tensioning rail 2. The lower surface of the tensioning rail 2 has provided thereon, in the press-on area 8, an opening 9 used for receiving therein the engine oil exiting from a chain tensioner 23, and two lateral guide projections 10 for guiding the chain tensioner 23 in the area of the press-on area 8. On the tensioning side facing away from the lower surface of the tensioning rail 2, a sliding-contact surface 11 is provided, which serves to contact and guide the driving chain 21. The cylindrical projection 5 on the tensioning rail back facing the engine block 4 is arranged coaxially with the pivot bearing axle through the pivot bearing opening 12 of the tensioning rail 2, the pivot bearing opening 12 extending also through the cylindrical projection 5.

(9) The engine block 4 has provided thereon a cylindrical assembly opening 6, which is incorporated in the engine block 4, e.g. cut or bored thereinto, the inner wall of the assembly opening 6 defining a loose fit relative to the cylindrical projection 5 of the tensioning rail 2, the amount of play of said loose fit being approx. 0.5 mm. Thus, the cylindrical projection 5 can easily be arranged in the assembly opening 6 and moved during the assembly operation, without taking the risk of an axial displacement relative to the pivot bearing in the pivot bearing opening 12 during operation.

(10) FIG. 2 shows the tensioning rail 2 at a mounting position on the engine block 4, at which the cylindrical projection 5 is accommodated in the assembly opening 6 on the engine block 4. In addition, a part of a second tensioning rail 13 including a sliding body 14 for guiding an associated driving chain (not shown) can be seen. On the second tensioning rail 13, a second pivot bearing opening 15 can be seen, which is supported by means of truss members 7 relative to the tensioning side of the second tensioning rail 13, said tensioning side being provided with the sliding body 14. The tensioning rail 2 arranged in the assembly opening 6 has provided thereon, on the tensioning rail upper surface located opposite the cylindrical projection 5, three stop projections 16 protruding relative to the support body 3 on the upper surface of the tensioning rail 2 and defining a stop for the second tensioning rail 13 in the area of the pivot bearing opening 15, so that the pivot bearing opening 12 of the first tensioning rail 2 and the second pivot bearing opening 15 of the second tensioning rail 13 are in alignment with one another.

(11) The mounting method shown in FIGS. 3 to 6 shows perspective top views of a bipartite drive with tensioning rails 2, 13 having the same pivot bearing axle. FIG. 3 shows a chain drive assembly 1 in a first mounting step. The tensioning rail 2 of the first, lower chain drive 17 is positioned between the first driving chain wheel 18 and the first driven chain wheel 19 such that the cylindrical projection 5 facing the engine block 4 is introduced in the cylindrical assembly opening 6 on the engine block 4. In addition, the assembly opening 6 has provided therein a threaded hole 20, in which a pivot bearing bolt 24 can be secured in position. After having established the first tensioning rail 2 at a mounting position on the engine block 4 through insertion of the cylindrical projection 5 in the assembly opening 6, the first driving chain 21 of the first chain drive 17 can be wrapped around the first driving chain wheel 18, the first driven chain wheel 19, the first tensioning rail 2 and the first guide rail 22, cf. FIG. 4. In so doing, the technician need not additionally fix the first tensioning rail 2 when applying the driving chain 21, since, through the cylindrical projection 5 and the assembly opening 6, it is sufficiently held at the mounting position on the engine block 4.

(12) For finishing the assembly of the first chain drive 17, a chain tensioner 23 is arranged between the guide rail 22 and the tensioning rail 2, as shown in FIG. 5, the tensioning piston (not shown) of said chain tensioner 23 pressing onto the press-on area 8 of the tensioning rail 2 and securing via the guide projections 10 the arrangement of the tensioning rail 2 via the cylindrical projection 5 in the assembly opening 6.

(13) The next mounting step shown in FIG. 6 and carried out for installing a bipartite chain drive in an internal combustion engine shows the arrangement of the second tensioning rail 13 of the second chain drive in the area of the pivot bearing opening 12 of the first tensioning rail 2, the second tensioning rail 13 resting on the stop projections 16 arranged around the pivot bearing opening 12. When the second tensioning rail 13 has been arranged at the mounting position on the first tensioning rail 2, the pivot bearing bolt 24 which is common to the first tensioning rail 2 and the second tensioning rail 13 can be inserted through the first pivot bearing opening 12 and the second pivot bearing opening 15 and fixed in position in the threaded hole 20 on the engine block 4, so as to define the pivot bearing 25 for the first tensioning rail 2 and the second tensioning rail 13. In the course of this process, the circumferential surface of the cylindrical projection 5, which is provided on the first tensioning rail 2 and arranged in the assembly opening 6 with a loose fit, is transferred to a contact-free position, so that the cylindrical projection 5 in the assembly opening 6 will be functionless during operation. Subsequently, the driving chain of the second chain drive (not shown) can be mounted safely and easily and can be fixed by means of a second chain tensioner.

LIST OF REFERENCE NUMERALS

(14) 1 chain drive assembly 2 tensioning rail 3 support body 4 engine block 5 cylindrical projection 6 assembly opening 7 truss members 8 press-on area 9 opening 10 guide projections 11 sliding-contact surface 12 pivot bearing opening 13 second tensioning rail 14 sliding body 15 pivot bearing opening 16 stop projections 17 first chain drive 18 driving chain wheel 19 driven chain wheel 20 threaded hole 21 driving chain 22 guide rail 23 chain tensioner 24 pivot bearing bolt 25 pivot bearing