Pulley arrangements, especially for tensioning idler pulleys or moving rollers

Abstract

The pulley device (1) comprises a pulley (2) and a bearing (3). The pulley (2) has two pulley parts (17, 18) with a C-shaped cross section. The pulley parts (17, 18) each comprise an inner part (22, 30), an outer cylindrical part (19, 27) and a radial middle part (25, 33). The middle part (25, 33) has a generally arc-shaped cross section.

Description

Technical Field

[0001] The invention relates to the field of pulley arrangements for tensioning idlers or runner rollers which are designed to interact with a chain or a belt, for example with a distribution belt of an internal combustion engine of a vehicle. Background Art

[0002] These rollers are usually used to maintain a constant tension on a belt or chain within a determined range or to locally change the path taken by the chain or belt. These are called tensioning idlers or moving rollers, respectively. In a moving roller, the pulley is mounted to rotate on a screw ( / screw) or spindle via rolling bearings, and the moving roller is then attached directly or indirectly to the engine block or to an element of the tensioning idler device, such as an articulated arm or an eccentric.

[0003] Document GB190509598 discloses a pulley comprising a male overlap portion and a female overlap portion which are in interlocking relationship and form a cylindrical outer portion for contact with a belt.

[0004] The main drawback of this pulley is the formation of an annular recess on the outer portion (which is adapted to support the belt when the male and female parts are tightened together). There is therefore a risk of premature belt wear.

[0005] A pulley is also known from document GB 141829, which comprises an outer peripheral portion for contact with the belt, an inner portion and an intermediate portion between the inner portion and the outer portion. The pulley is fastened to the outer ring of the bearing, but during service use of the pulley arrangement, the pulley may move slightly in the axial direction. In addition, with this disclosed pulley, the outer portion may deform radially inwards by bending under the action of the belt.

[0006] In document DE 20 2005 011 230 U1 it has been proposed to house a damping ring in a C-shaped pulley, the damping element being used to damp vibrations from the belt and being suitable for limiting radially inward deformations of the outer portion of the pulley. However, the pulley may still deform under heavy loads. Summary of the invention

[0007] The object of the present invention is to overcome these drawbacks by proposing a pulley that is easy to mount on bearings, has good rigidity, is suitable for avoiding premature wear of the belt and allows effective support of said belt.

[0008] To this end, the invention relates to a pulley arrangement suitable for a tensioning idler wheel or a moving roller interacting with a belt or a chain, the pulley arrangement comprising a bearing and a pulley.

[0009] The bearing comprises a rotatable outer ring and a fixed inner ring, wherein the outer ring and the inner ring are coaxial.

[0010] The pulley includes at least one pulley portion having a generally C-shaped cross-section and having an inner portion, an outer cylindrical portion and a radial middle portion, the inner portion having an inner surface mounted on the outer cylindrical surface of the outer ring of the bearing, the outer cylindrical portion having an outer cylindrical surface for contacting a belt or chain, the radial middle portion extending generally in the radial direction between the axial ends of the inner portion and the outer cylindrical portion on one axial side of the pulley device, the pulley portion being integrally formed and defining an open end on an axial side opposite to the middle portion.

[0011] According to the invention, the middle portion has a cross section which is generally in the shape of an arc circle.

[0012] According to further advantageous but non-mandatory aspects of the invention, such a pulley arrangement may comprise one or more of the following features:

[0013] The bearing is a rolling bearing, and at least one row of rolling elements is radially interposed between the inner ring and the outer ring.

[0014] - The rolling elements are balls.

[0015] The rolling elements are spaced equidistantly in the circumferential direction and are held by an annular cage.

[0016] The pulley is formed by only one pulley part.

[0017] The pulley comprises two C-shaped pulley parts mounted on the outer cylindrical surface of the outer ring of the bearing, the open ends of the pulley parts facing each other in the axial direction, and the free ends of the outer parts of the pulley parts in axial abutment.

[0018] - The two pulley parts are symmetrical with respect to a transverse radial plane passing through the centre of the bearing.

[0019] The outer portion of the pulley part has an axial length greater than an axial length of the inner portion, the outer portion protruding axially on at least one axial side of the inner portion.

[0020] - The pulley part is made from a stamped metal sheet ( / plate) or blank.

[0021] The ratio between the material thickness of the middle portion of the pulley part and the material thickness of the inner portion of the pulley part is strictly greater than 1.

[0022] - the ratio between the material thickness of the middle portion of the pulley part and the material thickness of the inner portion of the pulley part is comprised between 1.1 and 1.5, advantageously said ratio is equal to 1.25.

[0023] - said outer cylindrical portion and said middle portion of the pulley part have equal thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will now be explained with reference to the accompanying drawings which are intended as illustrative examples and not to limit the purpose of the invention. In the drawings:

[0025] - Figure 1 is an axial cross section of the pulley device according to the first embodiment of the present invention; and

[0026] - Figure 2 is set at Figure 1 An axial cross section of a pulley portion of a pulley arrangement. DETAILED DESCRIPTION

[0027] like Figure 1 to Figure 2 As shown, the pulley arrangement 1 is suitable for a tensioning idler or moving roller interacting with a belt or chain and comprises a pulley 2 suitable for interacting with a belt or chain (not shown) and a rolling bearing 3 having a geometric axis X1.

[0028] The rolling bearing includes a fixed inner ring 4, a rotatable outer ring 5, two annular retainers 8, 9 and two annular seals 10, 11. Two rows of rolling elements 6 and 7 are accommodated between the inner ring 4 and the outer ring 5. In this case, the rolling elements 6 and 7 are balls. The two annular retainers 8, 9 respectively maintain the circumferential spacing of the rolling elements 6, 7.

[0029] The inner ring 4 and the outer ring 5 are coaxial and symmetrical with respect to a transverse radial plane Y3 passing through the center of the rolling bearing 3. Advantageously, the rings 4, 5 are of the solid type. The solid type is understood to be a ring obtained by machining, grinding, by removing material from a metal tube ( / tube blank), a bar ( / bar blank), a rough forging and / or a rolled blank.

[0030] The inner ring 4 comprises a hole 12 for receiving a fastening screw 13 (shown in dotted lines) to fasten the device 1 to an external support. The inner ring also comprises an outer cylindrical surface 14 on which is formed an annular raceway whose cross section has a concave inner profile adapted to the rolling elements 6,7.

[0031] The outer ring 5 comprises a cylindrical hole 15 on which a circular ring raceway is formed, the cross section of which has a concave inner profile suitable for receiving the rolling elements 6 , 7 . The outer ring 5 also comprises an outer cylindrical surface 16 .

[0032] The pulley 2 has two pulley parts 17 , 18 , both having a generally C-shaped cross section.

[0033] The first pulley part 17 comprises an axial annular outer portion 19 providing a cylindrical outer surface 20 designed to interact with a portion of a belt or chain and a cylindrical inner surface or bore 21 .

[0034] The first pulley part 17 further comprises an axial annular inner portion 22 providing an inner surface or bore 23 into which the outer cylindrical surface 16 of the outer ring 5 of the bearing 3 fits, and an outer surface 24 .

[0035] The outer portion 19 has a larger diameter than the inner portion 22, and radially surrounds the inner portion 22. Advantageously, the outer portion 19 has a larger axial length than the inner portion 22, and axially protrudes from at least one axial side of the inner portion 22.

[0036] The first pulley part 17 further comprises an annular radial middle portion 25 extending substantially radially between the axial ends of the inner portion 22 and the outer portion 19 at a first axial side of the pulley device 1 .

[0037] The first pulley part 17 then has a generally C-shaped cross section defining an open end 26 at one axial side of the pulley device 1. The first pulley part 17 is integrally formed.

[0038] The second pulley part 18 comprises an axial annular outer portion 27 providing a cylindrical outer surface 28 designed to interact with a portion of a chain or belt and a cylindrical inner surface or bore 29 .

[0039] The second pulley part 18 further comprises an axial annular inner portion 30 providing an inner surface or bore 31 into which the outer cylindrical surface 16 of the outer ring 5 of the bearing 3 fits, and an outer surface 32 .

[0040] The outer portion 27 has a larger diameter than the inner portion 30, and radially surrounds the inner portion 30. Advantageously, the outer portion 27 has a larger axial length than the inner portion 30, and axially protrudes on at least one axial side of the inner portion 30.

[0041] The second pulley portion 18 further comprises an annular radial middle portion 33, which extends substantially radially between the axial ends of the inner portion 30 and the outer portion 27 on a second axial side of the pulley device 1, wherein the second axial side is axially opposite to the first axial side.

[0042] The second pulley part 18 then has a generally C-shaped cross section defining an open end 34 at one axial side of the pulley device 1. The second pulley part 18 is integrally formed.

[0043] Advantageously, both pulley parts 17, 18 are made from a thin metal sheet or blank by folding, cutting and punching.

[0044] Advantageously, the two C-shaped pulley parts 17, 18 are symmetrical to each other with respect to the radial plane Y3. The free ends of the outer portion 19 of the first pulley part 17 and the free ends of the outer portion 27 of the second pulley part 18 are in contact with each other in the axial direction, and the open ends 26, 34 are respectively axially facing each other (open). The two outer cylindrical surfaces 20, 28 form surfaces for interacting with a belt or chain. The pulley 2 formed by the two pulley parts 17, 18 configured to be in axial contact with each other is suitable for guiding and supporting a belt or chain in an effective manner.

[0045] Advantageously, the inner portion 22, 30 of the pulley portion 17, 18 is cylindrical, and the inner surface 23, 31 is cylindrical. As an alternative, the inner portion may be frustoconical, and the inner surface is frustoconical and slopes toward the outer surface 16 of the outer ring 5. Advantageously, the inner surface 23, 31 of the inner portion 22, 30 is press-fitted onto the outer cylindrical surface 16 of the outer ring 5.

[0046] According to the present invention, the middle portion 25 of the pulley portion 17 connects the outer portion 19 and the inner portion 22 and has a generally circular arc-shaped cross section.

[0047] Similarly and symmetrically, the middle portion 33 of the pulley portion 18 connects the outer portion 27 and the inner portion 30 and has a generally arc-shaped cross-section.

[0048] According to an advantageous embodiment, the material thickness e25 of the middle portion 25 of the pulley portion 17 is strictly greater than the material thickness e22 of the inner portion 22. Advantageously, the ratio between the material thickness e25 of the middle portion 25 of the pulley portion 17 and the material thickness e22 of the inner portion 22 of the pulley portion 17 is comprised between 1.1 and 1.5, advantageously, said ratio is equal to 1.25.

[0049] According to an advantageous embodiment, the middle portion 25 of the pulley portion 17 has equal thickness to the outer cylindrical portion 19. The material thickness e19 of the outer cylindrical portion 19 of the pulley portion 17 in radial direction is strictly greater than the material thickness e22 of the inner portion 22 in radial direction.

[0050] Advantageously, the ratio between thickness e19 and thickness e22 is comprised between 1.1 and 1.5, preferably, said ratio is equal to 1.25.

[0051] Similarly and symmetrically, the material thickness of the middle portion 33 of the pulley portion 18 is strictly greater than the material thickness in radial direction of the inner portion 30. Advantageously, the ratio between the material thickness of the middle portion 33 of the pulley portion 18 and the material thickness of the inner portion 30 of the pulley portion 18 is comprised between 1.1 and 1.5, advantageously said ratio being equal to 1.25.

[0052] Advantageously, the pulley portions 17 , 18 are symmetrical relative to a radial plane Y3 passing through the centre of the bearing 3 , the outer portions 19 , 27 then having an equal thickness e19 and the inner portions 22 , 30 also having an equal thickness e22 .

[0053] Thanks to the invention, the outer portion 19, 27 is reinforced and is thus less subject to deformation when radial loads are applied by the pulley or chain. As a result, the pulley parts 17, 18 are more robust.

[0054] Representative non-limiting examples of the present invention are described in detail above with reference to the accompanying drawings. This detailed description is intended only to teach those skilled in the art more details for practicing the preferred aspects of the present teachings, and is not intended to limit the scope of the present invention. In addition, each of the additional features and teachings disclosed above can be used alone or in combination with other features and teachings to provide an improved pulley device.

[0055] Furthermore, various features of the representative examples described above and the various independent and dependent claims below may be combined in ways not specifically and expressly recited to provide other useful embodiments of the present teachings.

Claims

1. A pulley device (1) suitable for a tensioning idler wheel or a moving roller, wherein the tensioning idler wheel or the moving roller interacts with a belt or a chain, the pulley device (1) comprising: - a bearing (3) having a rotatable outer ring (5) and a fixed inner ring (4), said outer ring (5) and said inner ring (4) being coaxial; and - a pulley (2) comprising two C-shaped pulley portions (17, 18), each of the pulley portions (17, 18) having an inner portion (22, 30) having an inner surface (23, 31) mounted on the outer cylindrical surface (16) of the outer ring (5), an outer cylindrical portion (19, 27) having an outer cylindrical surface (20, 28) configured to contact the belt or the chain, and a radial intermediate portion (25, 33) extending substantially radially between an axially outer end of the inner portion (22, 30) and an axially outer end of the outer cylindrical portion (19, 27), each of the two pulley portions (17, 18) being integrally formed and defining an open end (26, 34) on an axial side opposite to the radial intermediate portion (25, 33); Characterized in that the radial middle portion has a circular arc-shaped cross section, The open ends of the two pulley parts face each other in the axial direction, The axially inner ends of the inner portion are axially spaced apart from each other, The axially inner ends of the outer cylindrical portions axially abut against each other.

2. The pulley device according to claim 1, characterized in that: The pulley (2) is formed by only one pulley part (17, 18).

3. The pulley device according to claim 1, characterized in that: The pulley (2) comprises two C-shaped pulley parts (17, 18) mounted on the outer cylindrical surface (16) of the outer ring (5) of the bearing (3), the open ends (26, 34) of the pulley parts facing each other in the axial direction, and the free ends of the outer parts (19, 27) of the pulley parts (17, 18) abutting axially.

4. The pulley device according to claim 3, characterized in that: The two pulley parts (17, 18) are symmetrical with respect to a transverse radial plane (Y3) passing through the center of the bearing (3).

5. The pulley device according to any one of claims 1 to 4, characterized in that The pulley parts (17, 18) are made from stamped metal sheets or blanks.

6. The pulley device according to any one of claims 1 to 4, characterized in that The ratio between the material thickness (e25) of the middle portion (25, 33) of the pulley portion (17, 18) and the material thickness (e22) of the inner portion (22, 30) of the pulley portion (17, 18) is strictly greater than 1.

7. The pulley device according to claim 6, characterized in that The ratio between the material thickness (e25) of the middle portion (25, 33) of the pulley portion (17, 18) and the material thickness (e22) of the inner portion (22, 30) of the pulley portion (17, 18) is comprised between 1.1 and 1.

5.

8. The pulley device according to claim 6, characterized in that The outer cylindrical portion (19, 27) and the middle portion (25, 33) of the pulley portion (17, 18) have equal thickness.

9. The pulley device according to claim 6, characterized in that: The ratio between the material thickness (e25) of the middle portion (25, 33) of the pulley portion (17, 18) and the material thickness (e22) of the inner portion (22, 30) of the pulley portion (17, 18) is equal to 1.25.

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