Tensioning or guide rail with opening

Abstract

Tensioning or guide rail (5) for a chain drive (1), in particular a chain drive of an internal combustion engine, with two spaced-apart contact areas (10, 11) and a non-contact area (12) arranged between them, wherein the contact areas (10, 11) each have a sliding surface (14.1, 15.1) that can be brought into contact with a chain (4) and the non-contact area (12) serves as a support structure connecting the two contact areas (10, 11) to each other, characterized in that the support structure of the non-contact area (12) has an opening (33) extending from a front to a rear of the tensioning or guide rail (5) and separating the contact areas (10, 11) with the sliding surfaces (14.1, 15.1) from each other, wherein two spaced-apart side walls (18.1, 18.2) are provided, between which the sliding surfaces (14.1, 15.1) of the contact areas (10, 11) are partially located. are arranged so that the opening (33) forms a window.

Description

[0001] The present invention relates to a tensioning or guide rail for a chain drive, in particular a chain drive of an internal combustion engine, with two spaced-apart contact areas and a non-contact area arranged between them, wherein the contact areas each have a sliding surface that can be brought into contact with a chain and the non-contact area serves as a support structure connecting the two contact areas.

[0002] A guide rail of the type mentioned above is known, for example, from DE 19719732 C1. The slide rail described therein rests against the tension side of a timing drive of an internal combustion engine and has two spaced-apart sliding sections connected by a common, intervening support. Each sliding section is provided with a sliding coating made of polyamide without fiber additives. The support has a double-T-shaped cross-section to provide sufficient strength in the direction of the contact force. Preferably, the support can be made of a high-strength polyamide with fiber additives. The rationale behind this design is to reduce the weight and material usage of a slide rail.

[0003] Another sliding rail with spaced-apart sliding sections is known from DE 102007026939 A1. This is a one-piece sliding rail that can be manufactured with minimal effort. The recessed sections between the sliding sections reduce friction.

[0004] These designs reduce friction on the one hand and lead to a reduction in material usage on the other. However, due to the downsizing of combustion engines, installation space constraints are increasingly common, making it difficult to accommodate such clamping and guide rails.

[0005] The object of the present invention is therefore to produce a low-friction clamping or guide rail with minimal material usage, which can be positioned in a space-saving manner.

[0006] This problem is solved according to the invention in a clamping or guide rail of the generic type by the fact that the support structure of the non-contact area has an opening extending from a front to a rear of the clamping or guide rail, separating the contact areas with the sliding surfaces from one another, wherein two spaced-apart side walls are provided, between which the sliding surfaces of the contact areas are partially arranged, so that the opening forms a window. This allows the support structure of the non-contact area to be either very narrow or to have a cutout (opening) in the area of ​​which adjacent components or extraneous contours, such as engine block housings, etc., can extend into the area of ​​the support structure of the non-contact area and thus be brought relatively close to a chain.For this reason, a tensioning or guide rail constructed in this way must be positioned very close to these foreign contours or additional components, even in the section of its non-contact area. Essentially, only a minimal distance to the chain needs to be maintained in this area, sufficient to accommodate the chain's vibrations under load. Furthermore, the chain guide can be designed so that the force transmitted from the chain to the rail is concentrated in specific areas. These areas can be made particularly reinforced. Conversely, this allows for the targeted relief of stress on a specific area of ​​the rail, enabling the chain to be positioned very close to the motor's contour.

[0007] Preferably, the supporting structure of the non-contact area can be designed as at least one of the side walls connected to the contact areas and guided laterally along the sliding surfaces. The side walls have a very large cross-section in the load direction, but can be relatively thin in the width direction of the tensioning or guide rail. This allows for relatively large openings, creating particularly favorable installation conditions. The side walls can also be used for lateral guidance of the chain. Sufficiently high side walls result in good bending stiffness of the rail.

[0008] For optimal force absorption, the sliding surfaces are preferably convexly curved in the direction of chain travel. Due to the widely separated contact areas, the resulting normal force acting on the rail can be resolved into two areas.

[0009] The curvature ensures that the force is optimally introduced into the contact areas and, if necessary, directed to the fastening points. Furthermore, the curvature ensures optimal entry and exit of the chain. The opening is generally located at a distance below a tangent applied to the two contact areas. This means that the contact areas curve section by section in the direction of the opening.

[0010] According to a further embodiment, a support body can be provided that includes both the support structures of the contact areas and the support structure of the non-contact area, and two sliding surfaces connected to the support body, providing the respective sliding surfaces, can be provided. Both the support body and the sliding surfaces can then be optimally adapted to their respective functional purpose. The materials selected for the support body are primarily chosen with regard to their strength, e.g., metals such as steel or fiber-reinforced plastics, and the sliding surfaces are selected with regard to their sliding properties, e.g., unreinforced polyamide or PTFE.

[0011] Accordingly, as mentioned, the support body can be made of a reinforced plastic and the sliding linings can be made of a plastic with a low coefficient of friction.

[0012] According to one variant, the side flange(s) can be curved with the same direction of curvature as the sliding surface. This curved shape of the side flange(s) results in a rigid construction and also offers the advantage that, in the central area of ​​the rail, it can closely conform to, for example, a motor contour, due to the preferably convex shape of the side flange(s) on the inside. This design provides additional advantages to the existing through-hole.

[0013] To maximize the space-saving advantages, the length of the opening can be 0.2 to 0.5 times, preferably 0.3 to 0.35 times, the length of the clamping or guide rail. Therefore, the rail is preferably divided into three sections of approximately equal length: the two contact sections and the intervening non-contact section. This results in an excellent compromise between strength and low weight, as well as good adaptability to the available installation space.

[0014] Furthermore, this rail can have an entry side and an exit side, with the height of the side flange(s) increasing continuously from the entry side to the exit side, at least in the section between the contact areas. The terms entry side and exit side refer to the sliding direction of the chain along the respective rail. The chain moves from the entry side to the exit side. This design accommodates the increasing chain forces on the rail and represents a corresponding optimization and adaptation to the force distribution.

[0015] Advantageously, two mounting points arranged at a distance from each other, or one mounting point and one support point, can be provided, with one of the two points being located essentially centrally in the longitudinal direction on the respective contact area. Mounting points here refer to the center points or central axes of the respective mounting option (opening, mounting bolt, etc.). The essentially central arrangement on the contact area leads to optimal force transmission to the mounting point. As a rule, the mounting point is located approximately on a radius of curvature corresponding to the curvature of the sliding surface.

[0016] The present invention also relates to an endless drive, in particular a chain drive of an internal combustion engine, with at least two sprockets, a chain laid around the sprockets and at least one tensioning or guide rail according to one of claims 1 to 11. Such an endless drive can have limited installation space and yet elegantly accommodate a tensioning or guide rail according to the invention.

[0017] Preferably, the tensioning or guide rail can be arranged at a narrow point, so that a stationary component (or an extraneous contour) extends to within 5 to 15 mm of the chain in the area of ​​the opening. Maintaining this distance depends on any vibration of the chain occurring in this section, ensuring that it does not strike the stationary component. Depending on the distance between the two contact areas, an even closer placement is possible.

[0018] Advantageously, the clamping or guide rail can be provided with two mounting points or one mounting point and one support point, with an imaginary connecting line between these points intersecting the stationary component. This allows the stationary component to project into the area of ​​the rail. With appropriate shaping, the rail can also be guided in an approximately arc-like shape around a protruding contour of the component.

[0019] An embodiment of the present invention will now be explained in more detail with reference to the drawings. The drawings show: Fig. 1: A schematic front view of a timing chain drive, Fig. 2: a guide rail according to the invention in a side view, Fig. 3: the guide rail made of Fig. 2 in a perspective top view, Fig. 4: a schematic sectional view of an installation situation of the tension rail made of Fig. 2 and Fig. 5: a schematic sectional view of the tension rail made of Fig. 2 with schematic load distribution shown.

[0020] The in Fig. The timing chain drive 1 for an internal combustion engine, as depicted in Figure 1, essentially comprises a crankshaft sprocket 2, two adjacent camshaft sprockets 3.1 and 3.2, a timing chain 4 running around these, a guide rail 5 attached to the engine housing, a tensioning rail 6 pivotably mounted on the engine housing, and a chain tensioner 7, whose tensioning piston 8 presses against the tensioning rail 6. In this case, the chain tensioner 7 is designed as a so-called insert chain tensioner, which is screwed into a wall 9 on the engine housing. However, the chain tensioner 7 could also be designed as a flange-mounted or surface-mounted chain tensioner. The crankshaft sprocket 2 drives the two camshaft sprockets 3.1 and 3.2 by means of the timing chain 4. The tension side of the chain 4 slides along the guide rail 5, and the slack side along the tensioning rail 6.The chain tensioner 7 must exert a sufficiently large force on the tensioning rail 6 to ensure reliable tensioning of the timing chain 4 across the entire operating range of the internal combustion engine. Highly dynamic processes take place within the chain tensioner 7, which also provides a damping function. The following section will use the... Fig. Sections 2 to 5 describe in detail an embodiment of a guide rail 5 according to the invention, as used in the chain drive according to Fig. 1 is used.

[0021] The guide rail 5 is essentially divided into three areas: the first contact area 10 at the inlet of the guide rail 5, the second contact area 11 at the outlet of the guide rail 5, and the non-contact area 12 connecting these two. The guide rail 5 comprises three components: a support body 13, a first sliding surface 14 at the first contact area 10, and a second sliding surface 15 at the second contact area 11. The support body 13 is molded in one piece and consists of a fiber-reinforced plastic. Structurally, the support body 13 is divided into an approximately triangular support structure 16 for the first contact area 10, an approximately triangular second support structure 17 for the second contact area 11, and two arc-shaped side walls 18.1 and 18.2 connecting the two support structures 16 and 17 of the non-contact area 12. The side walls 18.1 and 18.2 form the supporting structure of the non-contact area 12.

[0022] The first support structure 16 has a truss-like construction and comprises a straight end wall 19, a concavely curved rear wall 20, and a convexly curved front wall 21, on which the first sliding surface body 14 with sliding surface 14.1 is arranged. A fastening eyelet 22 with an elongated cross-section is located at the intersection of the end wall 29 and the rear wall 20. A cross brace 23 connects the front wall 21 to the fastening eyelet 22. A longitudinally extending retaining wall 24, which encloses the truss structure of the first support structure 16 except for the fastening eyelet 22, is located approximately in the middle of the width of the guide rail 5.

[0023] The second support structure 17 comprises a straight end wall 25, a concavely curved rear wall 26, and a convexly curved front wall 27 that supports the second sliding surface body 15. Approximately in the middle of the second support structure 17 is a circular-section mounting eyelet 28. A cross brace 29 connects the front wall 27 to the mounting eyelet 28 and the mounting eyelet 28 to the corner of the end wall 25 and the rear wall 26. The truss structure of the second support structure 17 is enclosed approximately in the middle by a retaining wall 30, except for the mounting eyelet 28.

[0024] The two side walls 18.1 and 18.2 each have a convex upper surface 31.1 and 31.2 and a concave lower surface 32.1 and 32.2. Overall, the side walls 18.1 and 18.2 are curved, with the height H of the side walls 18.1 and 18.2 increasing continuously from the inlet side to the outlet side of the guide rail 5, at least between the two contact areas 10 and 11. The side walls 18.1 and 18.2 are designed as bending beams and are relatively narrow but tall. The two side walls 18.1 and 18.2 are not connected to each other in the area between the two contact areas 10 and 11, forming a window-like opening 33. The width B D The width of the opening 33 essentially corresponds to the width of the sliding lining bodies 14 and 15 providing the sliding surfaces 14.1 and 15.1 (i.e., it is in the range of 0.9 to 1.2 times the width of the sliding surface 14.1 or 15.1). The length L DThe opening 33 corresponds to approximately 0.33 times the length L of the guide rail 5 (i.e., it is in the range of 0.2 to 0.5 times the length L of the guide rail 5).

[0025] The support body 13 and the two sliding lining bodies 14 and 15 can be joined together by two-component injection molding. Alternatively, the sliding lining bodies 14 and 15 could also be clipped on.

[0026] Based on the Fig. Section 4 now explains in more detail the effects of the guide rail 5 according to the invention. The arc-shaped design of the guide rail 5 with the two contact areas 10 and 11, in conjunction with the opening 33 between them, makes it possible to guide the guide rail 5 virtually around housing contours, housing elements, and other structures, and to bring these elements and contours relatively close to the outer surface 35 of the control chain 4. This allows the control chain 4 to be guided very close to the housing contour 34. In the most favorable case, the distance A in the area of ​​the opening 33 is approximately 10 mm (corresponding to the range of 5 to 15 mm). An imaginary connecting line V linking the centers or central axes of the mounting lugs 22 and 28 LDue to this design, the guide rail 5 intersects an intermediate contour of the engine block (i.e., a stationary component). This allows even very confined installation spaces to be optimally utilized.

[0027] Based on the Fig. Figure 5 also shows how the load distribution occurs in the contact areas 10 and 11. The section with the greatest load is located primarily above the mounting lugs 22 and 28, particularly due to the convex shape of the sliding surfaces 14.1 and 15.1. This load distribution reduces the peak forces, and the reduced length of the sliding surfaces 14.1 and 15.1 also reduces friction.

[0028] Even though it wasn't explicitly shown here, it can be seen from the... Fig.The design principle for a guide rail 5 shown in Figures 2 to 5 can also be applied to a clamping rail 6 in the same way. Instead of the fastening eyelet in the run-out area, the clamping rail 6 then has a pressure area for the clamping piston 8. The clamping rail 6 also has two spaced-apart contact areas 10, 11, which are connected to each other by means of the non-contact area 12 (in this specific case, the two side plates 18.1, 18.2). Reference symbol list 1 Timing chain drive 2 Crankshaft sprocket 3.1 Camshaft sprocket 3.2 Camshaft sprocket 4 Timing chain 5 guide rail 6 tension rail 7 chain tensioners 8 clamping pistons 9 wall 10 first contact area 11 second contact area 12 Non-contact area 13 supporting structures 14 first sliding lining body 14.1 first sliding surface 15 second sliding surface body 15.1 second sliding surface 16 first supporting structure 17 second supporting structure 18.1 Side cheek 18.2 Side cheek 19 Front wall 20 Back panel 21 Front wall 22 Mounting eyelet 23 Cross brace 24 Retaining wall 25 Front wall 26 Back panel 27 Front wall 28 fastening eyelet 29 Cross brace 30 retaining wall 31 Top 32 Underside 33 Breakthrough 34 contour 35 Outside A distance B D Width (breakthrough) H height Length L L D Length (breakthrough) V L connecting line

Claims

[1] Tensioning or guide rail (5) for a chain drive (1), in particular a chain drive of an internal combustion engine, with two spaced-apart contact areas (10, 11), a non-contact area (12) arranged between them, wherein the contact areas (10, 11) each have a sliding surface (14.1, 15.1) that can be brought into contact with a chain (4) and the non-contact area (12) serves as a support structure connecting the two contact areas (10, 11) to each other, characterized by , that the supporting structure of the non-contact area (12) has an opening (33) extending from a front to a rear of the clamping or guide rail (5) and separating the contact areas (10, 11) with the sliding surfaces (14.1, 15.1) from each other, wherein two side cheeks (18.1, 18.2) arranged at a distance from each other are provided, between which the sliding surfaces (14.1, 15.1) of the contact areas (10, 11) are partially arranged, so that the opening (33) forms a window. [2] Tensioning or guide rail (5) according to claim 1, characterized by , that the supporting structure of the non-contact area (12) is designed as side cheeks (18.1, 18.2) connected to the contact areas (10, 11) and guided at least partially laterally along the sliding surfaces (14.1, 15.1). [3] Tensioning or guide rail (5) according to claim 1 or 2, characterized by , that the sliding surfaces (14.1, 15.1) are each convexly curved in the direction of travel of the chain. [4] Tensioning or guide rail (5) according to one of claims 1 to 3, characterized by , that a support body (13) is provided which includes both support structures (16, 17) of the contact areas (10, 11) and the support structure of the non-contact area (12), and two sliding lining bodies (14, 15) connected to the support body (13) and providing the respective sliding surface (14.1, 15.1) are provided. [5] Tensioning or guide rail (5) according to claim 4, characterized by, that the support body (13) is made of a reinforced plastic and the sliding lining bodies (14, 15) are made of a plastic with a low coefficient of friction. [6] Tensioning or guide rail (5) according to one of claims 3 to 5, characterized by , that the side cheek(s) is / are curved with the same direction of curvature as the sliding surfaces (14.1, 15.1). [7] Clamping or guide rail (5) according to any of the preceding claims, characterized by that a length (L D ) of the breakthrough (33) in the range of 0.2 to 0.5 times, preferably 0.3 to 0.35 times, corresponds to the length (L) of the clamping or guide rail (5). [8] Clamping or guide rail (5) according to any of the preceding claims, characterized by that a width (B D ) of the breakthrough (33) corresponds to approximately 0.9 to 1.2 times the width (B) of the sliding surface (14.1, 15.1). [9] Tensioning or guide rail (5) according to any one of claims 3 to 8, characterized by , that the rail (5) has an inlet side and an outlet side and that the height (H) of the side cheek(s) (18.1, 18.2) increases continuously from the inlet side to the outlet side, at least in the section between the contact areas (10, 11). [10] Clamping or guide rail (5) according to any of the preceding claims, characterized by , that two attachment points arranged at a distance from each other or one attachment point and one support point are provided, wherein one of the two points is arranged essentially centrally in the longitudinal direction on the respective associated contact area (10, 11). [11] Endless drive (1), in particular chain drive of an internal combustion engine, with at least two sprockets (2, 3.1, 3.2), a chain (4) laid around the sprockets (2, 3.1, 3.2) and at least one tensioning or guide rail (5) according to one of claims 1 to 10. [12] Endless drive (1) according to claim 11, characterized by, that the tensioning or guide rail (5) is arranged at a narrow point, so that in the area of ​​the opening (33) a stationary component reaches the chain (4) at a distance (A) of 5 to 15 mm. [13] Endless drive (1) according to claim 11, characterized by , that two fastening points or one fastening point and one support point are provided on the clamping or guide rail (5) and an imaginary connecting line (V L ) these points intersect the stationary component (34).

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