Pulley units for tensioning or idler rollers

Abstract

The invention relates to a pulley device (1) for a tensioning roller or idler roller of a transmission element, the pulley device (1) comprising a pulley (2) and a bearing (3). The bearing is provided with a rotating outer ring (7) on which the pulley (2) is mounted, and is provided with a fixed inner ring (6), a radial space (8) defined between the inner ring (6) and the outer ring (7), a rear sealing member (23) and a front sealing member (24) closing the radial space (8) on each axial side, and at least one row of rotating elements (9, 10) arranged in the radial space (8). The fixed inner ring (6) is provided with a circumferential groove (36) on its rear side for collecting pollutants, the circumferential groove (36) being machined on the outer surface (14) of the inner ring (6), the circumferential groove (36) being axially offset outside the radial space (8) relative to the rear sealing member (23).

Description

Technical Field

[0001] The invention relates to the field of pulley arrangements for tensioning or idler rollers designed to cooperate with a transmission element, for example a timing or drive belt or a timing or drive chain of an internal combustion engine of a motor vehicle. Background Art

[0002] Such rollers are usually used to keep the tension in the transmission element permanently within a certain range or to locally change the path taken by the transmission element. These rollers are called tensioning rollers or idler rollers, respectively. In the case of an idler roller, the pulley is rotatably mounted on a screw with a threaded body by means of a bearing, and the roller is then fixed directly or indirectly to the engine block or to an element of the tensioning roller arrangement, such as an articulated arm or an eccentric.

[0003] The bearing generally comprises a fixed inner ring having holes through which screws pass, a rotating outer ring surmounted by a pulley, and at least one row of rotating elements between the inner and outer rings.

[0004] Such devices are often equipped with sealing joints or additional protective flanges that help protect the device from contamination or from contaminants originating from the external environment.

[0005] However, particles or other contamination elements may penetrate into the immediate vicinity of the sealing components of the bearing, and these particles or other contamination elements may accumulate in the immediate vicinity of the sealing components of the bearing over time. The sealing components may wear, and the risk of contaminants penetrating into the bearing cavity increases with the service life of the pulley device. Such internal contaminants may lead to accelerated degradation of the internal components of the bearing, in particular, may lead to accelerated degradation of the contact surface between the rotating element and the ring. This in turn may also lead to a reduction in the quality of the rotating mechanical connection provided by the pulley device and to a reduction in the service life of the internal components of the pulley device. In particular, the risk of breakage is also high in operating mode. Summary of the invention

[0006] The present invention proposes to solve this inconvenience.

[0007] More specifically, the invention proposes the use of a pulley arrangement that is resistant in conditions of high pollution, is particularly economical, has a simple and safe assembly, forms a non-detachable subassembly and has reduced overall axial and radial dimensions.

[0008] The invention relates to a pulley device for a tensioning roller or an idler roller of a transmission element. The pulley device comprises a pulley and a bearing. The pulley has an outer surface for cooperating with the transmission element.

[0009] The bearing is provided with a rotating outer ring, a fixed inner ring, a rear sealing component and a front sealing component and at least one row of rotating elements, the pulley is mounted on ( / surmounted) the rotating outer ring and the rotating outer ring is provided with a hole having at least one outer raceway, the fixed inner ring has a hole for receiving a screw, an outer surface having at least one inner raceway, a rear lateral surface for contacting with a support member of the device and a front lateral surface for contacting with a head of the screw, the inner ring and the outer ring are coaxial and a radial space is formed between the inner ring and the outer ring, the rear sealing component and the front sealing component close the radial space on each axial side, and the at least one row of rotating elements is arranged in the radial space and is located between the inner raceway and the outer raceway.

[0010] According to the present invention, the fixed inner ring is provided with a circumferential groove for collecting pollutants at the rear side of the fixed inner ring, and the circumferential groove is machined on the outer surface of the inner ring. The circumferential groove is axially offset relative to the rear sealing component outside the radial space.

[0011] Other advantageous but non-mandatory features according to the invention used alone or in combination:

[0012] The pulley device comprises an annular protective flange having a substantially radial portion with an inner edge forming a hole and with an outer edge next to the pulley to form a narrow channel, the substantially radial portion being in contact with the front lateral surface of the fixed inner ring.

[0013] The flange comprises a retaining member together with a fixed inner ring of the bearing.

[0014] The flange includes an annular collar extending axially from an outer edge of the substantially radial portion.

[0015] The collar is cylindrical.

[0016] The collar is frusto-conical.

[0017] The inner ring of the bearing is integral.

[0018] The inner ring of the bearing includes a track element, a spacer, a rear lateral surface and a front lateral surface, wherein the track element is provided with an outer surface having at least one inner raceway for a rotating element, the spacer is provided with an outer surface mounted in a hole of the track element, the hole being used to receive a screw, the rear lateral surface being used to contact with a support member of the device, and the front lateral surface being used to contact with a head of the screw.

[0019] Circumferential grooves for collecting contaminants are provided on the outer surface of the track element of the inner ring.

[0020] Circumferential grooves for collecting contaminants are provided on the outer surfaces of the spacers of the inner ring.

[0021] The pulley arrangement comprises a retaining member for cooperating with the screw.

[0022] The bore of the fixed inner ring comprises an inner circumferential groove in which an annular O-ring cooperating with the screw is accommodated.

[0023] The cage ensures that the circumferential spacing of the rotating elements is maintained.

[0024] At least one inner raceway is constituted by a circumferential groove having, in axial section, a concave inner contour adapted to the rotating element.

[0025] The rotating element is a ball.

[0026] The at least one raceway has an axial cross section with a toroidal profile adapted to the ball.

[0027] The circumferential groove for collecting pollutants has a circular ring profile in its axial cross section.

[0028] The circumferential grooves for collecting contaminants are the same as the circumferential grooves forming the inner raceway.

[0029] The fixed inner ring comprises a cylindrical outer surface provided with at least one raceway and a circumferential groove for collecting contaminants.

[0030] The pulley includes a front axial projection.

[0031] The pulley includes a rear axial projection.

[0032] The front axial protrusion radially surrounds the outer edge of the flange.

[0033] The rear axial protrusion radially surrounds the circumferential groove for collecting pollutants.

[0034] The pulley is mounted on the outer surface of the rotating outer ring of the bearing.

[0035] The pulley and the rotating outer ring of the bearing are formed integrally, and the rotating outer ring is provided with an outer surface for cooperating with the transmission element.

[0036] The pulley is made of metal, for example steel.

[0037] The pulley is made of a plastic material, for example polyamide.

[0038] The pulley is formed by over-moulding a plastic material onto the outer ring of the bearing.

[0039] The flange is made of metal, for example steel.

[0040] The flange is made of a plastic material, for example polyamide. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The following is provided by way of non-limiting example by perusing the single accompanying drawing ( Figure 1 ) will make it easier to understand the present invention. Figure 1 ) represents an axial cross-sectional view of the pulley device according to the present invention. DETAILED DESCRIPTION

[0042] As can be understood from the figure, the pulley device for the tensioning roller or idler roller of the belt (which is generally indicated by the reference numeral 1) has a geometric axis X1 and comprises a pulley 2 suitable for cooperating with a transmission element (not shown here) such as a belt or chain, a bearing 3, a protective flange 4 and a screw 5.

[0043] The bearing 3 comprises a fixed inner ring 6 and a rotating outer ring 7, which are coaxial with respect to the axis X1 and form a radial space 8 between them. The bearing 3 also comprises two rows of rotating elements 9 and 10, which are realized in the form of balls and are arranged between the two rings, and cages 11 and 12, which ensure the circumferential spacing of the rotating elements 9 and 10, respectively.

[0044] The inner ring 6 and the outer ring 7 are coaxial. In the embodiment shown, the ring is solid, that is to say it is obtained by machining or grinding with material removal on the basis of a metal tube, a bar, a forged part or a rolled blank.

[0045] The inner ring 6 comprises a hole 13, an outer cylindrical surface (or cylindrical outer surface) 14, and two rear lateral surfaces 17 and a front lateral surface 18. The outer cylindrical surface 14 is provided with raceways 15, 16, the axial section of which has a concave inner profile and has a toroidal form suitable for the rotating elements 9, 10.

[0046] The outer ring 7 includes a cylindrical hole 19, an outer cylindrical surface (or cylindrical outer surface) 20, and two rear lateral surfaces 21 and a front lateral surface 22. The cylindrical hole 19 is provided with a raceway (not shown here), the axial cross-section of which has a concave inner contour and has a ring form suitable for the rotating elements 9 and 10, and the pulley 2 is mounted on the outer cylindrical surface 20.

[0047] The fixed inner ring 6 extends axially beyond the rotating outer ring 7 in an axially rearward direction towards the support on which the pulley device 1 is mounted. The rear lateral surface 17 serves to form a contact surface for the bearing 3 against the support for the device 1.

[0048] Advantageously, the bearing 3 comprises an annular seal 23 , 24 on each axial side to close the radial space 8 present between the inner ring 6 and the outer ring 7 and housing the rotating elements 9 , 10 inside it.

[0049] Advantageously, the sealing joints 23, 24 each comprise a first fixed extremity located in a circumferential groove provided in the bore 19 of the outer ring 7 and a second extremity formed by a lip resting in sliding contact against the outer cylindrical surface 14 of the inner ring 6. In this way, the radial space 8 is closed axially between the two sealing joints 23, 24 in a sealed manner.

[0050] As an alternative, the bearing may include a different number of rows of rotating elements arranged between the outer ring and the inner ring, such as a single row of rotating elements.

[0051] As an alternative, the bearing may comprise other types of rotating elements, such as tapered rollers, needle rollers or even tapered roller bearings.As an alternative, the bearing may be a plain bearing.

[0052] In this embodiment, the inner ring 6 is formed integrally. According to an alternative embodiment (not shown here), the bearing 3 may comprise an annular spacer mounted in the inner ring 6 .

[0053] The pulley 2 comprises an outer cylindrical surface 25 for cooperating with a transmission element such as a belt or a chain, and an inner surface 26 integral with the outer ring 7. The pulley has a substantially tubular form and is centred on a central axis X1.

[0054] Advantageously, the pulley 2 can be made of a plastic material, and preferably can be made of a polyamide, such as PA6 or PA66. Advantageously, the pulley 2 can be formed by overmolding a plastic material on the outer ring 7 of the bearing 3. This creates excellent cohesion between these components. As an alternative, the pulley 2 can be made of a metal material, such as steel, and can be press-fitted onto the outer cylindrical surface 20 of the outer ring 7. The pulley 2 can also have other forms optimized for the needs of the application.

[0055] According to another alternative, the outer surface 20 of the outer ring 7 can cooperate directly with a transmission element, in order in doing so to form a pulley for the pulley arrangement 1 .

[0056] The screw 5 comprises a body 27 and a head 28 at the axial end of said body 27. The body 27 is housed in the bore 13 of the bearing 3 and extends axially beyond the rear lateral surface 17 of the fixed inner ring 6. The body 27 comprises a threaded portion intended to be screwed into a corresponding threaded opening of a support for the pulley device 1.

[0057] The protective flange 4 comprises a substantially radial portion 29 extending between an outer edge and an inner edge of the hole forming the flange 4 .

[0058] The radial portion 29 is substantially in contact with the front lateral surface 18 of the inner ring 6 , which is situated opposite the support on which the device 1 is mounted.

[0059] Advantageously, the bore 13 of the fixed inner ring 6 of the bearing 3 comprises, at its rear extremity, an inner circumferential groove 37. An annular O-ring 38 is inserted in said inner circumferential groove 37 to axially and radially retain the body 27 of the screw 5 in the pulley device 2. As an alternative, the pulley device 1 may comprise any other component suitable for the purpose of retaining the screw 5.

[0060] The head 28 of the screw 5 has a relatively flat surface in contact with a substantially radial portion 29 of the flange 4, said portion 29 being wedged axially between the head 28 of the screw 5 and the inner ring 6 of the bearing 3. According to a variant (not shown here), a washer may be inserted between the head of the screw and the substantially radial portion of the flange.

[0061] As an advantageous manner, the flange 4 also comprises an axial portion 30 extending axially from the inner edge of the radial portion 29. The axial portion 30 is housed in and interacts with the hole 13 of the inner ring 6 of the bearing 3. The axial portion 30 may be annular and have a substantially tubular form, or even discrete and formed with a plurality of tongues. The axial portion 30 allows the centering of the flange 4 relative to the bearing 3 on the one hand and the centering of the flange 4 relative to the pulley 2 on the other hand.

[0062] In the embodiment shown, the bore 13 is provided at its front extremity with a circumferential groove 31. The axial portion 30 is deformed radially in such a way that it is partially accommodated in said circumferential groove 31. The flange 4 is held together axially and radially with the bearing 3 by cooperating with its axial portion 30 with the wall of the circumferential groove 31 provided in the fixed inner ring 6. As an alternative, if the bearing is equipped with a spacer, the circumferential groove can be realized in the bore of the spacer of the bearing.

[0063] As an alternative (not shown here), the axial portion of the flange can be press-fitted into the bore of the bearing. According to other variants, the axial portion is mounted in the mounting bore of the bearing in an integrated manner by some other suitable means (eg, by gluing).

[0064] The pulley 2 comprises a rear axial protrusion 32 which extends axially beyond the rear lateral surface 21 of the outer ring 7 in the axial rearward direction of the device 1. The pulley 2 comprises a front axial protrusion 33 which extends axially beyond the front lateral surface 22 of the outer ring 7 in the axial forward direction of the device 1. The outer edge of the substantially radial portion 29 of the flange 4 extends adjacent to the front axial protrusion 33 of the pulley 2. The front axial protrusion 33 radially surrounds the outer edge of the substantially radial portion 29 of the flange 4 to form a narrow channel, which reduces the risk of external contaminants intruding into the vicinity of the bearing 3.

[0065] In the embodiment shown, the flange 4 advantageously comprises a cylindrical annular collar 34 extending axially in the axial forward direction from the outer edge of the substantially radial portion 29. Alternatively, the collar 34 may be frustoconical or of some other form suitable for preventing the ingress of contaminants. Alternatively, the collar 34 may extend axially in the axial rearward direction of the device 1.

[0066] The flange is formed by cutting after stamping a metal strip, for example a metal strip made of steel. As an alternative, the flange can be made of a plastic material, for example made of polyamide.

[0067] In accordance with the invention, the stationary inner ring 6 of the bearing 3 is provided on its rear side with a circumferential groove 36 for collecting contaminants.

[0068] A circumferential groove 36 is machined on the outer cylindrical surface 14 of the inner ring 6. The circumferential groove 36 is axially offset toward the rear of the inner ring 6 relative to the rear sealing member 23 so that the circumferential groove 36 is located outside the radial space 8.

[0069] The rear axially projecting portion 32 of the pulley 2 radially surrounds a circumferential groove 36 for collecting contaminants.

[0070] As a particularly advantageous manner, the circumferential groove 36 for collecting pollutants has a form similar to that of the raceways 15 and 16 provided on the cylindrical outer surface 14. Thus, the axial section of the circumferential groove 36 has a concave inner contour in the form of a circular ring. Due to this embodiment, the circumferential groove 36 can be machined on the same surface 14 in the same way as the raceways 15, 16, in the same form and with the same dimensions. As another alternative, the circumferential groove 36 can have any other axial cross-sectional form suitable for collecting pollutants, such as a parallelpipedal, triangular or other form.

[0071] Thanks to the invention, the contamination that manages to pass through the passage between the support for the device 1 and the pulley 2 at the rear of the device 1 is collected in the circumferential groove 36 at a distance from the rear seal 23 .

[0072] Furthermore, the technical features of the different embodiments can be combined among them, all of them, and only some of them. Therefore, the pulley device can be adjusted in terms of cost, performance, and ease of use.

Claims

1. A pulley device (1) for a tensioning roller or an idler roller of a transmission element, the pulley device (1) comprising: - a pulley (2) having an outer surface (25) for cooperating with said transmission element, and - a bearing, provided with a rotating outer ring (7), a fixed inner ring (6), a rear sealing member (23) and a front sealing member (24) and at least one row of rotating elements (9, 10), the pulley (2) being mounted on the rotating outer ring (7) and the rotating outer ring (7) being provided with a hole (19) with at least one outer raceway, the fixed inner ring (6) having a hole (13) for receiving a screw (5), an outer surface (14) with at least one inner raceway (15, 16), a support member (23) and a front sealing member (24) for contact with the device (1); a rear lateral surface (17) for contacting a support member and a front lateral surface (18) for contacting a head (28) of a screw (5), the inner ring (6) and the outer ring (7) are coaxial and form a radial space (8) between the inner ring (6) and the outer ring (7), the rear sealing member (23) and the front sealing member (24) close the radial space (8) on each axial side, the at least one row of rotating elements (9, 10) is arranged in the radial space (8) and is located between the inner raceway and the outer raceway, It is characterized in that the fixed inner ring (6) is provided with a circumferential groove (36) for collecting pollutants on the rear side of the fixed inner ring (6), and the circumferential groove (36) is machined on the outer surface (14) of the inner ring (6), and the circumferential groove (36) is axially offset on the outer side of the radial space (8) relative to the rear sealing component (23).

2. The pulley device according to claim 1, characterized in that: The rotating elements are balls (9, 10), and the at least one inner raceway (15, 16) is constituted by a circumferential groove having a concave inner contour in the form of a ring adapted to the balls (9, 10) in axial section.

3. The pulley device according to claim 2, characterized in that: The circumferential groove (36) for collecting pollutants is the same as the circumferential groove forming the inner raceway (15, 16) and the axial section of the circumferential groove (36) has a circular ring profile.

4. The pulley device according to any one of claims 1 to 3, characterized in that The fixed inner ring (6) comprises a cylindrical outer surface (14) provided with at least one raceway (15, 16) and the circumferential groove (36) for collecting pollutants.

5. The pulley device according to any one of claims 1 to 3, characterized in that The pulley (2) comprises a rear axial protrusion (32) which radially surrounds the circumferential groove (36) for collecting pollutants.

6. The pulley device according to any one of claims 1 to 3, characterized in that The pulley device (1) comprises an annular protective flange (4) having a radial portion (29) with an inner edge forming a hole and with an outer edge adjacent to the pulley (2) to form a narrow channel, the radial portion (29) being in contact with the front lateral surface (18) of the fixed inner ring (6).

7. The pulley device according to claim 6, characterized in that The flange (4) comprises a retaining member (30) together with the fixed inner ring (6) of the bearing (3).

8. The pulley device according to claim 6, characterized in that The flange (4) includes an annular collar (34) extending axially from an outer edge of the radial portion (29).

9. The pulley device according to any one of claims 1 to 3, characterized in that The pulley device (1) comprises a retaining member (37, 38) for cooperating with the screw.

10. The pulley device according to claim 9, characterized in that The hole (13) of the fixed inner ring (6) comprises an inner circumferential groove (37) in which an annular O-ring (38) cooperating with the screw (5) is accommodated.

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