Bearing Pivot Tensioner Assembly

Abstract

A belt tensioner having a tensioner base and a tensioning arm axially aligned about a pivot axis defining a pivot axis, the tensioning arm being free to pivot about the pivot axis relative to the tensioner base. The tensioner has a bearing about the pivot axis sealed to the pivot axis, the tensioning arm being disposed about the bearing. The bearing provides a radial seal between the bearing and the tensioning arm and between the bearing and the pivot axis. A torsion spring is disposed externally about a portion of the tensioning arm.

Description

[Background technology]

[0001] Belt tensioners are commonly known devices used in many belt drive systems. Tensioners typically provide a constant belt tension that compensates for increases in belt length due to wear, belt stretching (e.g., due to temperature increases), and other factors.

[0002] A typical belt tensioner includes a fixed structure and an oscillating structure coaxially mounted to the fixed structure by a pivot assembly, with the oscillating structure having a belt tensioning pulley rotatably mounted thereto. A coil spring surrounds the pivot assembly and has an end connected between the fixed structure and the oscillating structure to bias the oscillating structure in a belt wrapping direction. As the oscillating structure moves from a minimum belt wrapping position to a maximum belt wrapping position, the spring biasing force decreases. Despite this varying spring force over the tensioner's range of travel, a relatively constant belt tension is maintained by the tensioner.

[0003] There is always room for alternative belt tensioner designs. Summary of the Invention

[0004] The present disclosure provides a tensioner for a belt system, the tensioner having a tensioner base and a tensioning arm axially aligned about a pivot axis defining a swing axis, the tensioning arm being swingable about the swing axis relative to the tensioner base. The tensioner has a bearing sealed to the pivot axis around the pivot axis, the tensioning arm being disposed around the bearing. The bearing forms a radial seal between the bearing and the tensioning arm and between the bearing and the pivot axis. A torsion spring is disposed externally around a portion of the tensioning arm.

[0005] In one particular embodiment, the present disclosure provides a belt tensioner for a belt drive, the tensioner comprising: a tensioner base; a tensioning arm axially aligned about a pivot axis defining a swing axis, the tensioning arm pivotable relative to the tensioner base about the swing axis; a pivot bearing disposed about the pivot axis and sealed relative to the pivot axis; the tensioning arm disposed about the bearing; and a torsion spring disposed about a portion of the tensioning arm.

[0006] In another specific embodiment, the present disclosure provides a belt tensioner for a belt drive, the tensioner including a tensioner base and a tensioning arm having a pulley connected thereto, the tensioner base having a pivot axle defining an oscillation axis extending through the tensioner base and the tensioning arm, a pivot bearing radially disposed between the pivot axle and the tensioning arm, a torsion spring radially disposed between the pivot axle and the tensioning arm, and a damping mechanism disposed between the compression spring and the tensioning arm.

[0007] In yet another specific embodiment, the present disclosure provides a belt tensioner for a belt drive, the tensioner including a tensioner base and a tensioning arm, the tensioner base having a pivot shaft defining an oscillation axis extending through the tensioner base and the tensioning arm, and a bearing disposed radially between the pivot shaft and the tensioning arm, the bearing providing a radial seal between the bearing and the tensioning arm and between the bearing and the pivot shaft.

[0008] These and other features of the tensioner described herein will become apparent after review of the detailed description and drawings. However, the scope of claimed subject matter is determined by the claims as written, and not whether given subject matter addresses some or all of the problems described in the "Background" or includes features described in the "Summary." [Brief explanation of the drawings]

[0009] FIG. 1 is a typical top view of a tensioner.

[0010] FIG. 2 is a representative cross-sectional side view of the tensioner taken along line 2-2 of FIG.

[0011] FIG. 3 is a representative exploded perspective view of the tensioner of FIGS.

[0012] FIG. 4 is a representative side view of another embodiment of the tensioner.

[0013] FIG. 5 is a representative top view of another embodiment of the tensioner.

[0014] FIG. 6 is a representative cross-sectional view of the tensioner taken along line 6-6 of FIG.

[0015] FIG. 7 is a representative exploded perspective view of the tensioner of FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0016] As noted above, the present disclosure is directed to a belt tensioner having an internal bearing for sealing the internal structure of the belt tensioner.

[0017] Belt tensioners apply tension to, for example, a belt or front-end accessory drive (FEAD) through a pulley with a bearing. The tensioner has a tensioning arm that rotates or swings around a tensioner base to adjust the tension on the pulley and belt. Inside the tensioner, the tensioning arm and tensioner base form a cavity that contains a mechanism for damping the arm's motion and a pivot surface that provides low-friction bearings. However, contaminants can enter this cavity in two ways: they can affect the performance and durability of the tensioner by causing accelerated wear and / or by adversely affecting the coefficient of friction between the two surfaces.

[0018] One conventional method for sealing tensioners to prevent contaminants from entering the cavity is to create a labyrinth or complex path between the arm and base. The labyrinth between the arm and base is integrally formed by the arm and / or base, but is not always effective in extreme conditions. An additional element, a seal plate, is often used to create the labyrinth.

[0019] Another conventional approach to sealing tensioners is to use a cap to seal the pivot area. The cap is also an additional element and requires an additional assembly step to apply pressure to seat the cap. If not seated properly, the cap will loosen over time, i.e., during operation of the vehicle to which the tensioner is attached.

[0020] The belt tensioner of the present disclosure provides an alternative mode of tensioner contamination containment. As described above, the belt tensioner uses a bearing within a cavity to seal the internals of the belt tensioner. A double-row bearing can be used, which provides a very robust bearing surface and provides stable pulley alignment. Due to the tight fit between the pivot shaft and tensioning arm, the bearing forms a radial seal, which also seals areas of the damping mechanism, such as a damping plate and / or internal compression spring, thus avoiding the need for additional mechanisms or parts to seal the tensioner. The compression spring may further seal the damping mechanism within the cavity. The compression spring presses the damping mechanism against the rotatable tensioning arm, creating a frictional force.

[0021] The benefits provided by the belt tensioner of the present disclosure include a high level of precision in pulley bearing alignment and improved pivot resistance to normal wear and wear due to contaminant infiltration into the tensioner. Additionally, the damping mechanism within the aperture benefits from a contaminant-free area and provides a more consistent and stable damping force over time due to the presence of less contaminants. Less wear in the damping mechanism results in a more consistent torque output over time.

[0022] In another embodiment, by using a pivot bearing instead of a plastic or metal bushing, it is possible to seal the damping mechanism within the tensioner through the use of a seal plate or gasket that seals the area between the tensioning arm and the base. This improves the durability of the pivot from the use of a pivot bearing and damping mechanism.

[0023] In the following description, reference numerals are affixed to the accompanying drawings that form a part of the specification and are shown for purposes of illustration in at least one specific embodiment. The following description provides additional specific embodiments. Other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense. The present disclosure is not limited, but an appreciation of the various features of the present disclosure can be gained through the description of examples, including the drawings described below. In some instances, a reference numeral may have an associated subscript consisting of a lowercase letter to indicate one of multiple similar elements. When a reference numeral is a reference numeral without specifying a subscript, the reference numeral is intended to refer to all multiple similar elements.

[0024] Referring to the drawings, Figure 1 shows a tensioner 100, such as a FEAD (Front End Accessory Drive). The tensioner 100 has a base structure 110 and a tensioning arm 120 that is pivotable about an axis of pivot of the tensioner 100 relative to the base structure 110. Although the tensioner 100 is specifically shown as part of a FEAD, the tensioner 100 may be modified as needed for use in appropriate applications.

[0025] Figure 2 is a cross-sectional side view of tensioner 100 taken along line 2-2 of Figure 1. Figure 3 also shows tensioner 100 in an exploded view.

[0026] The base structure 110 and the tensioning arm 120 are rotatably coupled to one another to form the tensioner 100. A pivot axis 112 extends through the tensioner base 110 and the tensioning arm 120 and defines the oscillation axis of the tensioner 100, i.e., the axis of rotation between the tensioner base 110 and the tensioning arm 120. The pivot axis 112 is fixed relative to the tensioner base 110 and, in some embodiments, is integral with the tensioner base 110. The tensioning arm 120 rotates or oscillates, or at least partially rotates, about the pivot axis 112.

[0027] The pivot bearing 114 surrounds the pivot axle 112 in the region or opening between the tensioning arm 120 and the pivot axle 112. The pivot bearing 114 is centered about the pivot axle 112 and the axis of rotation and seats on a shoulder of the pivot axle 112. In other embodiments, the underside of the pivot bearing 114 frictionally engages a surface of the tensioner base 110. The pivot bearing 114 has a length that is shorter than the length of the pivot axle 112. In some embodiments, the pivot bearing 114 is fixed to the pivot axle 112, and the tensioning arm 120 rotates relative to the pivot bearing 114. In other embodiments, the pivot bearing 114 is fixed to the tensioning arm 120, and rotates with the tensioning arm 120 relative to the pivot axle 112 and the tensioner base 110. In still other embodiments, the pivot bearing 114 is fixed to both the tensioning arm 120 and the pivot axle 112, and rotation occurs within the bearing 114.

[0028] The pivot bearing 114 may be a rolling bearing, i.e., a ball bearing or a roller bearing, and may or may not have a tapered profile. The particular pivot bearing 114 shown in Figure 2 is a double row ball bearing.

[0029] In the area or opening where the pivot bearing 114 is located, a compression spring 116 is located, further from the tensioner base 110 than the pivot bearing 114. The compression spring 116 generates a damping force. Like the pivot bearing 114, the compression spring 116 is centered about the pivot axis 112 and the axis of rotation and extends axially. The compression spring 116 may be a coil spring with a constant diameter or a diameter that varies along its length. Any suitable helical shape, wire diameter and / or cross-section (e.g., circular, rectangular, elliptical), material, free length, and spring end shape can be used for the compression spring 116. In some embodiments, alternative designs can be used for the compression spring 116, such as a spiral spring, torsion spring, or leaf spring, or even a Belleville washer. In some embodiments, two parallel coil springs may be used, for example two parallel compression springs or one compression spring may be the inner spring and a torsion spring may be the outer spring.

[0030] Additionally, in the region or opening where the pivot bearing 114 and compression spring 116 are located, the damping mechanism 118 is located farther from the tensioner base 110 than the pivot bearing 114, and in the illustrated embodiment, farther from the tensioner base 110 than the compression spring 116. Like the pivot bearing 114 and the compression spring 116, the damping mechanism 118 is centered about the pivot axis 112 and the axis of rotation and extends axially. The damping mechanism 118 is a disk, and may be made of, for example, metal, resin, or a combination thereof. The damping mechanism 118 has a central hole that allows the damping mechanism 118 to slide axially along the pivot axis 112, but is restricted from rotational movement relative to the axis 112.

[0031] On the outside of tensioning arm 120 is a torsion spring 119, which rotates about pivot axis 112 and at least pivot bearing 114. Torsion spring 119 may have any leg arrangement or position.

[0032] 3 is an exploded perspective view of tensioner 100, showing tensioning arm 120 having pulley 122 around which the belt to be tensioned is disposed. Pulley 122 and dust shield 124 are secured to arm 120 by bolt 125.

[0033] FIG. 3 shows the arrangement of pivot shaft 112 with pivot bearing 114, compression spring 116, damping mechanism 118 and torsion spring 119, all along a central axis which is also the axis of rotation.

[0034] It should be noted that the elements including the pivot shaft 112, pivot bearing 114, compression spring 116, damping mechanism 118, and torsion spring 119 are generally radially symmetric about the swing axis. As shown in FIG. 1, the base structure 110 and tensioning arm 120 are not symmetric about the swing axis.

[0035] 2 and 3, in some embodiments, the tensioner 100 does not have a traditional labyrinth or dust cap aligned with the pivot axis 112, or axis of rotation. Rather, the tensioner 100 uses a pivot bearing 114 and associated seal to protect the damping mechanism 118 from external contaminants that may enter through the interface between the base structure 110 and the tensioning arm 120. External contaminants must pass through the bearing seal to affect the pivot area and the damping mechanism 118.

[0036] The compression spring 116 is also protected by a seal in the pivot bearing 114 .

[0037] To assemble the belt tensioner 100, the pivot bearing 114 is first pressed against the tensioner base 110 around the pivot shaft 112 and then against the arm 120 having the torsion spring 119 around it to create a protective area for the damping mechanism.

[0038] Figures 4, 5, 6, and 7 show an alternative embodiment of tensioner 100. Figure 4 shows a side view of the tensioner. Figure 5 shows a top view of the tensioner. Figure 6 is a cross-sectional side view of the tensioner taken along line 6-6 in Figure 5. Figure 6 is an exploded perspective view of the embodiment shown in Figures 4 and 5.

[0039] The base structure 110 and the tensioning arm 120 are rotatably coupled to one another to form the tensioner 100. A pivot axis 112 extends through the tensioner base 110 and the tensioning arm 120 and defines the oscillation axis of the tensioner 100, i.e., the axis of rotation between the tensioner base 110 and the tensioning arm 120. The pivot axis 112 is fixed relative to the tensioner base 110 and, in some embodiments, is integral with the tensioner base 110. The tensioning arm 120 rotates or oscillates, or at least partially rotates, about the pivot axis 112.

[0040] The pivot bearing 114 surrounds the pivot axle 112 in the region or opening between the tensioning arm 120 and the pivot axle 112. The pivot bearing 114 is centered about the pivot axle 112 and the axis of rotation and seats on a shoulder of the pivot axle 112. In other embodiments, the underside of the pivot bearing 114 frictionally engages a surface of the tensioner base 110. The pivot bearing 114 has a length that is shorter than the length of the pivot axle 112. In some embodiments, the pivot bearing 114 is fixed to the pivot axle 112, and the tensioning arm 120 rotates relative to the pivot bearing 114. In other embodiments, the pivot bearing 114 is fixed to the tensioning arm 120, and rotates with the tensioning arm 120 relative to the pivot axle 112 and the tensioner base 110. In still other embodiments, the pivot bearing 114 is fixed to both the tensioning arm 120 and the pivot axle 112, and rotation occurs within the bearing 114.

[0041] The pivot bearing 114 may be a rolling bearing, i.e., a ball bearing or a roller bearing, and may or may not have a tapered profile. The particular pivot bearing 114 shown in Figures 2 and 3 is a double row ball bearing.

[0042] 5 illustrates another embodiment of a bearing seal tensioner assembly. In this embodiment, a base structure 110 and a tensioning arm 120 are rotatably coupled to one another to form the tensioner 100. A pivot axis 112 extends through the tensioner base 110 and the tensioning arm 120 and defines the oscillation axis of the tensioner 100, i.e., the axis of rotation between the tensioner base 110 and the tensioning arm 120. The pivot axis 112 is fixed relative to the tensioner base 110 and, in some embodiments, is integral with the tensioner base 110. The tensioning arm 120 rotates or oscillates, or at least partially rotates, about the pivot axis 112.

[0043] The pivot bearing 114 surrounds the pivot axle 112 in the area or opening between the tensioning arm 120 and the pivot axle 112. The pivot bearing 114 is centered about the pivot axle 112 and the axis of rotation and seats on a shoulder of the pivot axle 112. In other embodiments, the pivot bearing 114 may be located radially between the pivot axle 112 and the torsion spring 119. The pivot bearing 114 has a length that is shorter than the length of the pivot axle 112. In some embodiments, the pivot bearing 114 is fixed to the pivot axle 112, and the tensioning arm 120 rotates relative to the pivot bearing 114. In other embodiments, the pivot bearing 114 is fixed to the tensioning arm 120 and rotates with the tensioning arm 120 relative to the pivot axle 112 and the tensioner base 110. In yet another embodiment, the pivot bearing 114 is fixed to both the tensioning arm 120 and the pivot shaft 112 , with rotation occurring within the bearing 114 .

[0044] The pivot bearing 114 may be a rolling bearing, i.e., a ball bearing or a roller bearing, and may or may not have a tapered profile. The particular pivot bearing 114 shown in Figure 6 is a double row ball bearing.

[0045] In some embodiments, the torsion spring 119 may be interrupted, fixed, connected, or attached to the tensioning arm 120 at a first end, and interrupted, fixed, connected, or attached to the damping mechanism 118 at a second end. Rotation of the tensioner about its central axis when a belt load is applied causes the torsion spring 119 to contract or expand, changing the damping force provided by the torsion spring 119 via the damping mechanism 118 as it radially contacts the inner wall surface of the tensioning arm 120. In some embodiments, damping may occur via the damping mechanism 118 contacting the tensioner base 110 radially and / or axially. In this embodiment, the torsion spring is held between the tensioning arm 120 and the inner wall of the tensioner base 110. The torsion spring 119 generates the damping force. The torsion spring 119 may be radially disposed about the pivot axis 112. Torsion spring 119 may be a torsion spring having a constant diameter or a diameter that varies along its length. Any suitable helical shape, wire diameter and / or cross section (e.g., circular, rectangular, oval), material, free length, and spring end shape may be used for torsion spring 119. In some embodiments, alternative designs may be used for torsion spring 119, such as a spiral spring or a coil spring. Torsion spring 119 may have any leg arrangement or position.

[0046] Additionally, a damping mechanism 118 may be provided. In some embodiments, the damping mechanism 118 is radially disposed between the pivot shaft 112 and the tensioning arm 120. Similar to the pivot bearing 114 and the torsion spring 119, the damping mechanism 118 is radially centered about the pivot shaft 112 and the axis of rotation and extends axially. The damping mechanism 118 may be an arc-shaped structure having the same radius as the inner wall of the tensioning arm 120. The damping mechanism may also be shaped like a block, plate, disc, or the like. The damping mechanism 118 may be molded from metal, resin, or a combination thereof. The damping mechanism 118 may be disposed around a second end of the torsion spring 119, the second end being the end of the torsion spring that is interrupted, fixed, connected, or not attached to the tensioning arm 120.

[0047] 7 is an exploded perspective view of tensioner 100 showing tensioning arm 120 having pulley 122 around which the belt to be tensioned is disposed. Pulley 122 and dust shield 124 are secured to arm 120 by bolts 125 or other securing mechanisms such as, but not limited to, locking pins, push pins, latch clips, etc.

[0048] FIG. 7 shows the arrangement of pivot shaft 112 with pivot bearing 114, damping mechanism 118 and torsion spring 119, all of which are aligned along a central axis which is also the axis of rotation.

[0049] It should be noted that the elements including the pivot shaft 112, pivot bearing 114, and torsion spring 119 are generally radially symmetric about the swing axis. As shown in Figure 7, the base structure 110, damping mechanism, and tensioning arm 120 are not symmetric about the swing axis.

[0050] As shown in FIG. 6 , in other embodiments, the tensioner 100 has a conventional labyrinth aligned with the pivot axis 112, or swing axis. However, the tensioner 100 uses a pivot bearing 114 and associated seal to protect the damping mechanism 118 from external contaminants. However, contaminants that may enter through the interface between the base structure 110 and the tensioning arm 120 have a difficult time entering the internal regions of the tensioner due to the labyrinths molded into the tensioning arm 120 and the tensioner base 110. In some embodiments, with the use of the pivot bearing 114 and damping mechanism 118, a seal such as a rubber gasket, polymer gasket, or the like may be used between the tensioner base 110 and the tensioning arm 120 to seal the tensioning spring 119 and damping mechanism 118 from contaminants. The pivot bearing 114 and damping mechanism 118 extend the life of the tensioner 100. In other embodiments, the pivot bearing 114 and damping mechanism 118 may allow for packaging of short or long arm tensioners.

[0051] The various embodiments and variations of tensioner 100 may be formed from any material, including metals (e.g., iron, steel, aluminum), composites (e.g., ceramics), polymeric materials, or combinations thereof. Any of the elements and components may have coatings thereon to reduce surface friction, improve airworthiness, reduce physical wear, increase chemical resistance, etc.

[0052] The above specification and examples provide a complete description of the structure and use of exemplary embodiments of the present invention. The above description is of a specific example. It should be understood that other examples are contemplated and may be implemented without departing from the scope and spirit of the present disclosure. Therefore, the above detailed description should not be taken in a limiting sense. The present disclosure is not limited, but an understanding of various features of the present disclosure will be gained from the discussion of the examples provided.

[0053] The tensioners described herein and various variations may be incorporated into a wide range of belt drive systems and other systems, including ABDS (Accessory Belt Drive Systems), SBDS (Synchronous Belt Drive Systems), BSG (Belt Starter Generators, e.g., for hybrid vehicles), dual arm tensioners, CVT (Continuously Variable Transmission) serpentine belts, water pumps, timing, etc. The tensioners may be used with V-belts, micro-V-belts, double V-belts, flat belts, round belts, etc., molded and reinforced from rubber or polymers (e.g., polyurethane).

[0054] Unless otherwise specified, all numbers expressing shapes, sizes, and physical properties are to be understood as being modified by the term "about," whether or not the term "about" is immediately preceding them. Accordingly, unless indicated to the contrary, the numerical parameters described will vary depending upon the desired properties expected to be obtained by one of ordinary skill in the art employing the techniques employed in the teachings disclosed herein.

[0055] As used herein, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" generally includes "and / or" unless the content clearly dictates otherwise.

[0056] When used in this specification, spatial terms, including but not limited to "bottom," "low," "top," "upper," "below," "under," "upper," "peak," "above," and the like, are used as a convenient descriptor to describe spatial relationships between elements. Such spatial terms include different positions of the device in addition to the specific positions shown in the drawings and described in the specification. For example, when a structure shown in the drawings is inverted or flipped over, parts previously described as lower or lower elements of other elements become upper or upper elements.

Claims

1. A tensioner base, a tensioning arm axially aligned about a pivot axis defining a swing axis, the tensioning arm being swingable relative to the tensioner base about the swing axis; a pivot bearing disposed around the pivot shaft and tightly fitted and sealed to the pivot shaft and the tensioning arm, the tensioning arm being disposed around the pivot bearing; a torsion spring disposed around a portion of the tensioning arm; a damping mechanism and a compression spring, the damping mechanism and the compression spring being disposed around the pivot shaft; The pivot bearing is disposed axially between the compression spring and the tensioner base, and the compression spring is disposed axially between the pivot bearing and the damping mechanism. Belt tensioner for belt drives.

2. A tensioner as described in claim 1, wherein the tensioning arm is arranged around the pivot axis.

3. 2. The tensioner of claim 1, wherein the pivot bearing is axially disposed between the damping mechanism and the tensioner base.

4. 2. The tensioner of claim 1, wherein the pivot bearing is disposed radially between the torsion spring and the tensioner base, and the compression spring is disposed axially between the pivot bearing and the damping mechanism.

5. 2. The tensioner of claim 1, wherein said pivot bearing is a double row ball bearing.

6. A tensioner base and a tensioning arm are provided, the tensioner base has a pivot shaft defining a swing axis, the swing axis extending through the tensioner base and the tensioning arm; a pivot bearing disposed radially between the pivot shaft and the tensioning arm, the pivot bearing fitting tightly between the pivot bearing and the tensioning arm and between the pivot bearing and the pivot shaft to form a radial seal; a damping mechanism and a compression spring, the damping mechanism and the compression spring being disposed around the pivot shaft; The pivot bearing is disposed axially between the compression spring and the tensioner base, and the compression spring is disposed axially between the pivot bearing and the damping mechanism. Belt tensioner for belt drives.

7. A tensioner as described in claim 6, wherein the tensioning arm is arranged around the pivot axis.

8. 7. The tensioner of claim 6, wherein the pivot bearing is axially disposed between the damping mechanism and the tensioner base.

9. 7. The tensioner of claim 6, wherein said compression spring defines a radial seal between said compression spring and said tensioning arm and between said compression spring and said pivot shaft.

10. 7. The tensioner of claim 6, further comprising a torsion spring disposed about a portion of the tensioning arm.

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