Axial damping tensioner

Abstract

A tensioner for a belt is provided, the tensioner having an independently adjustable force that presses a pulley into the belt and provides a damping effect for the tensioner. A tensioner includes a base bracket secured to, for example, an engine block, an arm rotatably engaged with the base bracket, and a pulley rotatably engaged with the arm. A biasing member, such as a spring, is positioned between the arm and the base bracket, and the biasing member generates a torsional force in response to angular displacement, where the torsional force presses the pulley into the belt. The biasing member then generates an axial force in response to the axial displacement, where the axial force presses the arm into a damping bushing unit to generate a damping effect. Thus, these forces are independently adjustable, and the arrangement of the components also reduces the tilt between the arm and the base bracket.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 491,421, filed March 21, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a tensioner for a belt and pulley system, the tensioner keeping the belt taut against the pulley and providing a damping function to reduce oscillation of the tensioner components and reduce vibration in the belt. Background Technology

[0004] Belt and pulley systems are used to transmit power from one pulley to one or more other pulleys via a belt. Furthermore, belt and pulley systems are particularly useful for transmitting power between rotating components. Therefore, belt and pulley systems are commonly included in internal combustion engines to transmit power from the engine's output shaft to other components such as compressors, water pumps, and alternators. A tensioner is a component that presses the freely rotating pulleys into the belt to keep the belt taut against other pulleys and ensure efficient power transmission. Additionally, the tensioner can be selectively disengaged to allow for quick belt changes. The tensioner can also provide damping to reduce oscillations in its components and absorb vibrations in the belt caused by variations in the transmission and reception of power through the belt, movement between components, and other vibration sources.

[0005] In some prior art tensioners, a spring is used to drive the pulley into the belt, and the same spring is used to drive the friction plate into the tensioner housing to provide a damping function. An example of such a prior art device is shown in U.S. Patent No. 5,632,697, which is incorporated herein by reference in its entirety. In this arrangement, both the force generated by the spring to drive the pulley and the force generated by the spring to press the friction plate depend on the angular displacement of the spring. This arrangement of components inhibits the function of the tensioner because any choice affecting the ability of the spring to drive the pulley will necessarily alter the damping function, and vice versa.

[0006] Furthermore, using friction plates in this manner leads to uneven wear on both the friction plates and the tensioner housing, causing some components to tilt and misalign. This tilting results in further uneven wear. To address the wear problem, some components of the tensioner may need to be replaced, or the entire tensioner may need to be replaced; otherwise, the user faces the risk of catastrophic failure in the belt and pulley system's ability to transmit power. Therefore, the arrangement of components in existing devices makes functional adjustment difficult and results in uneven wear and tilting, imposing additional costs and risks on the user. Summary of the Invention

[0007] Embodiments of the present disclosure address these and other drawbacks of prior art tensioners. In particular, the tensioners of the present disclosure provide a torsional force that presses a pulley into a belt and an axial force that dampens movement of the tensioner, and these forces are independently adjustable to easily control the performance of the tensioner. Furthermore, the tensioners of the present disclosure better prevent any tilting between the arm and the base bracket of the tensioner to improve the performance and life of the tensioner.

[0008] One aspect of the present disclosure is to provide a tensioner that generates independently adjustable torsional and axial forces. In some embodiments, the tensioner has a base bracket that is fixed to, for example, an engine block, an arm that pivots about the base bracket, and a pulley at a distal end of the arm that presses into a belt to keep the belt taut. A spring is operably engaged with the base bracket and the arm to control movement between the base bracket and the arm. Specifically, the spring winds up or unwinds to generate a torsional force that rotates the arm and presses the pulley into the belt. The torsional force is a function of a torsional spring constant and an angular displacement of the spring. The spring is then compressed in an axial direction to generate an axial force that presses the arm into a damping bushing unit for a damping effect. The axial force is a function of an axial spring constant and an axial displacement of the spring. Since the torsional force depends on the angular displacement and the axial force depends on the axial displacement (which is different from the angular displacement), the torsional and axial forces are independently adjustable to easily control the performance of the tensioner.

[0009] For example, in some embodiments, it is desirable to increase the axial force of the spring without changing the torsional force that determines the force and torque that the pulley of the tensioner exerts on the belt to change the damping effect of the tensioner. Therefore, a spring is selected that has a longer, uncompressed axial length, but no other changes that would affect other aspects of the spring. Thus, when the spring is compressed and installed with other components, the spring generates a greater axial force to change the damping effect of the tensioner, however, the torsional spring constant and the angular displacement of the spring remain unchanged. Therefore, the torsional force generated by the spring is not affected, or only slightly affected, by the change in length of the spring.

[0010] Another aspect of the present disclosure is to provide a tensioner that better resists tilting of an arm relative to a damping bushing unit and a base bracket of the tensioner. Tilting is typically caused by belt forces, and several aspects of the present disclosure help resist tilting, including the way the arm engages the damping bushing unit, which is joined to the base bracket. In particular, a shoulder of the arm engages a flange of the damping bushing unit in a damping engagement region, and a bore of the arm engages a body of the damping bushing unit in a rotational engagement region. The damping engagement region has a washer-like planar shape that is oriented perpendicular to the axes of the damping bushing unit and the base bracket. The rotational engagement region has a cylindrical shape that is centered about and extends along these axes. Having a damping engagement region that is separate from the rotational engagement region and has a different shape resists tilting of the arm.

[0011] In particular, the relative positions of the engagement regions help resist tilting. In some embodiments, forces from the belt are directed through the rotational engagement region, and the arm is urged to tilt about the forces relative to the damping bushing unit and the base bracket. With the damping engagement region separate from the rotational engagement region and extending farther in a lateral direction, so the damping engagement region resists tilting of the forces and the arm. In various embodiments, the damping engagement region is located near an upper end of the rotational engagement region. This arrangement is supported by a biasing member that drives the shoulder of the arm into the flange of the damping bushing unit with an axial force that promotes alignment of the arm and further resists tilting of the arm relative to the damping bushing unit and the base bracket. In some embodiments, the axial force can be selected to be greater than any belt forces that would cause the arm to tilt, to better resist tilting of the arm. This arrangement also results in more uniform wear between the arm and the damping bushing unit, and more uniform wear keeps the arm aligned relative to the damping bushing unit and the base bracket. Additionally, with the damping engagement region separate from the rotational engagement region, any wear between the contact surfaces in the damping engagement region has less of an effect on tilting of the arm.

[0012] The rotational interface region also has a number of functions. The rotational interface region can include a small gap between the inner surface of the bore of the arm and the outer surface of the body of the damping bushing unit. The smaller the gap, the less freedom the arm, particularly the bore, has to tilt relative to the damping bushing unit and the base bracket. Furthermore, with the belt force directed through the rotational interface region, the rotational interface region can better resist tilting than if the belt force were directed in another direction, for example, above the upper end of the rotational interface region or below the lower end of the interface region.

[0013] The rotational interface region can also provide some damping of oscillation of the arm relative to the damping bushing unit and the base bracket. Due to the small gap in the rotational interface region between the bore of the arm and the body of the damping bushing unit and / or the material selection of the bore and the body, there can be some engagement and friction in the rotational interface region. Thus, as the arm moves relative to the damping bushing unit and the base bracket, the rotational interface region can help resist that movement and the damping effect described herein.

[0014] Another aspect of the present disclosure is to provide a tensioner with fewer parts than prior art tensioners to improve the performance and life of the tensioner while reducing the manufacturing cost of the tensioner. In the case of prior art tensioners, due to the arrangement of the components in the prior art tensioners, a friction plate, a back plate, and other components are needed to provide a damping effect. In the present disclosure, by changing the arrangement of the components, the friction plate and the back plate are eliminated. Furthermore, other plates and bushings are combined into a damping bushing unit, which can be one or two components as described herein. The reduction in the number of parts simplifies the tensioner and reduces the number of potential failure points, thereby improving the performance and life of the tensioner.

[0015] A first aspect of the present disclosure is to provide a tensioner for a belt, comprising: an arm configured to rotate about an axis of a base bracket, the arm having a bore and a shoulder; a biasing member extending from a first end to a second end, wherein the first end is engaged with the arm and the second end is engaged with the base bracket; and a damping bushing unit coupled with the base bracket and at least partially positioned in the bore of the arm, wherein the shoulder of the arm and a flange of the damping bushing unit are configured to engage with each other in a damping interface region, and the biasing member is configured to drive the shoulder of the arm into the flange of the damping bushing unit in a direction parallel to the axis of the base bracket to generate a damping torque in the damping interface region.

[0016] The tensioner of the first aspect can optionally include a body of the damping bushing unit configured to engage the bore of the arm in a rotational engagement region to allow rotation of the arm about the base support.

[0017] The tensioner of the first aspect can include one or more of the preceding embodiments, and optionally the damping engagement region has a planar shape generally perpendicular to an axis of the base support, and the rotational engagement region has a cylindrical shape generally centered about the axis of the base support.

[0018] The tensioner of the first aspect can include one or more of the preceding embodiments, and optionally the damping bushing unit comprises: a shaft made of a first material; and a ring disposed about at least a portion of an outer surface of the shaft, wherein the ring is made of a second material different from the first material.

[0019] The tensioner of the first aspect can include one or more of the preceding embodiments, and optionally the damping bushing unit is a single continuous structure made of a plastic material.

[0020] The tensioner of the first aspect can include one or more of the preceding embodiments, and optionally a lower end of the damping bushing unit comprises an annular recess, and the base support comprises a cylindrical protrusion, wherein the protrusion is configured to press fit into the recess to join the damping bushing unit with the base support.

[0021] The tensioner of the first aspect can include one or more of the preceding embodiments, and optionally a mounting fastener extends through a threaded hole of the damping bushing unit and into a threaded portion of the base support to join the damping bushing unit with the base support.

[0022] A second aspect of the present disclosure provides a tensioner for a belt, the tensioner comprising: an arm configured to rotate about an axis of a base support, the arm having a bore and a shoulder; a damping bushing unit joined with the base support and at least partially positioned in the bore of the arm, wherein a shoulder of the arm and a flange of the damping bushing unit are configured to engage each other in a damping engagement region, and a body of the damping bushing unit is configured to engage the bore of the arm in a rotational engagement region to allow rotation of the arm about the axis of the base support; and wherein the damping engagement region has a planar shape generally perpendicular to the axis of the base support, and the rotational engagement region has a cylindrical shape generally centered about the axis of the base support.

[0023] The tensioner of the second aspect can optionally include a pulley rotatably engaged with the arm and configured to press into a belt, wherein the pulley includes a plurality of bearings oriented in a plane generally parallel to the damping interface region.

[0024] The tensioner of the second aspect can include one or more of the preceding embodiments, and optionally, the plane extends through the rotational interface region.

[0025] The tensioner of the second aspect can include one or more of the preceding embodiments, and optionally, the plane is offset from the damping interface region by a predetermined distance.

[0026] The tensioner of the second aspect can include one or more of the preceding embodiments, and optionally includes a biasing member extending from a first end to a second end, wherein the first end is engaged with the arm and the second end is engaged with the base bracket, wherein the biasing member is configured to drive a shoulder of the arm into a flange of the damping bushing unit in a direction parallel to the axis to generate a damping torque in the damping interface region, and wherein a diameter of the biasing member is less than an outer diameter of the damping interface region and greater than an inner diameter of the damping interface region.

[0027] The tensioner of the second aspect can include one or more of the preceding embodiments, and optionally, a body of the damping bushing unit extends downward from the flange such that the damping interface region is located near an upper end of the rotational interface region.

[0028] The tensioner of the second aspect can include one or more of the preceding embodiments, and optionally, the biasing member is a coil spring disposed around the bore of the arm and a body of the damping bushing unit.

[0029] A third aspect of the present disclosure provides a tensioner for a belt, comprising: an arm configured to rotate about an axis of a base bracket; a damping bushing unit coupled with the base bracket, wherein the damping bushing unit secures the arm to the base bracket; and a spring extending between a first end engaged with the arm and a second end engaged with the base bracket, wherein the spring is configured to exert a torsional force in response to an angular displacement of the spring between the arm and the base bracket, and the spring is configured to exert an axial force in response to an axial displacement of the spring between the arm and the damping bushing unit, wherein the torsional force and the axial force are independently adjustable.

[0030] The tensioner of the third aspect can optionally include a pulley rotatably engaged with the arm and configured to press into a belt, wherein the pulley includes a plurality of bearings oriented in a plane generally parallel to a damping engagement region in which a shoulder of the arm and a flange of the damping bushing unit are configured to engage one another, wherein the axial force generates a damping torque in the damping engagement region.

[0031] The tensioner of the third aspect can include one or more of the preceding embodiments, and optionally, the plane extends through a rotational engagement region in which a bore of the arm and a body of the damping bushing unit are configured to engage one another to permit rotation of the arm about the base support.

[0032] The tensioner of the third aspect can include one or more of the preceding embodiments, and optionally, the damping engagement region has a planar shape generally perpendicular to an axis of the base support and the rotational engagement region has a cylindrical shape generally centered about the axis of the base support.

[0033] The tensioner of the third aspect can include one or more of the preceding embodiments, and optionally, the body of the damping bushing unit extends downward from the flange such that the damping engagement region is located near an upper end of the rotational engagement region.

[0034] The tensioner of the third aspect can include one or more of the preceding embodiments, and optionally, a diameter of the spring is less than an outer diameter of the damping engagement region and greater than an inner diameter of the damping engagement region.

[0035] As used herein, the phrases “at least one”, “one or more” and “and / or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B, and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and / or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.

[0036] Unless otherwise indicated, all numbers expressing quantities, dimensions, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless otherwise indicated, the numerical parameters are approximations.

[0037] As used herein, the term “a” entity is defined to mean one or more of the entity. Thus, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein.

[0038] The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Accordingly, the terms "including," "comprising," or "having" and variations thereof can be interchangeable in this disclosure. The use of "consisting essentially of, or variations thereof, is meant to encompass the items listed thereafter and equivalents thereof, but exclude additional items. The use of "consisting of, or variations thereof, is meant to encompass only the items listed thereafter. The use of "connected," "coupled," or "in communication with," and variations thereof herein is meant to encompass both direct and indirect connections or couplings.

[0039] It should be understood that the term "means," as used in this document, is given its broadest possible interpretation in accordance with 35 U.S.C. § 112(f). Accordingly, the term "means" encompasses all structures, materials, or acts that perform the functions described in this document, as well as those that are known to be equivalent to the performance of the functions described in this document.

[0040] These and other advantages will be apparent from the disclosure of the invention(s) contained herein. The above-described embodiments, objectives, and configurations are meant to be illustrative only and are not intended to exhaustively enumerate all possibilities or aspects of the disclosure. The summary is neither intended to be nor should it be construed as representing the entire disclosure and scope of the disclosure. Additionally, reference herein to "the invention" or aspects thereof should be understood as referring to certain embodiments of the invention / disclosure and should not be interpreted as a complete description affecting all possible embodiments of the invention. The invention is set forth in the summary and is further described in the detailed description and the appended drawings. No limitation is intended to the scope of the invention based on whether an element or component is described in the summary or not. Additional aspects of the invention will become apparent from the detailed description, particularly when taken together with the drawings.

[0041] It should be understood that any of the features or aspects described herein can be claimed in combination with any of the other features or aspects described herein, regardless of whether the features or aspects are from the same described embodiment.

[0042] Any one or more aspects described herein can be combined with any other one or more aspects described herein. Any one or more features described herein can be combined with any other one or more features described herein. Any one or more embodiments described herein can be combined with any other one or more embodiments described herein. BRIEF DESCRIPTION OF DRAWINGS

[0043] Those skilled in the art will recognize that the following description is merely illustrative of the principles of this disclosure, and that these principles can be applied in various ways to provide many different alternative embodiments. This description is intended to illustrate the general principles of the teachings of this disclosure and is not intended to limit the inventive concepts disclosed herein.

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate the embodiments and, together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of the invention.

[0045] Figure 1 This is a side elevation view of a pulley system according to an embodiment of the present disclosure;

[0046] Figure 2 A perspective view of a tensioner according to an embodiment of the present disclosure;

[0047] Figure 3 for Figure 2 A cross-sectional view taken along line AA of a tensioner according to an embodiment of the present disclosure;

[0048] Figure 4 An exploded perspective view of a tensioner according to an embodiment of the present disclosure;

[0049] Figure 5 A perspective view of a damping bushing unit according to an embodiment of the present disclosure;

[0050] Figure 6A A perspective view of a spring in its uncompressed state according to an embodiment of the present disclosure;

[0051] Figure 6B for Figure 6A A perspective view of a spring in a compressed state according to an embodiment of the present disclosure;

[0052] Figure 7 for Figure 2 A cross-sectional view taken along line BB of a tensioner according to an embodiment of the present disclosure;

[0053] Figure 8 for Figure 2 Another cross-sectional view of the tensioner according to an embodiment of the present disclosure, taken along line BB;

[0054] Figure 9 A cross-sectional view of another tensioner according to an embodiment of this disclosure; and

[0055] Figure 10 This is a cross-sectional view of another tensioner according to an embodiment of the present disclosure.

[0056] It should be understood that the drawings are sometimes shown simplified and not necessarily to scale, and that the various dimensions can vary. In some cases, details which are not necessary for the understanding of the application can have been omitted or made difficult to see. It goes without saying that the application is not necessarily limited to the particular embodiments illustrated herein.

[0057] 2 belt system

[0058] 4 primary crank pulley

[0059] 6a, 6b, 6c pulley

[0060] 8 belt

[0061] 10 tensioner

[0062] 12 base bracket

[0063] 14 center (base bracket)

[0064] 16 pulley

[0065] 18 center (pulley)

[0066] 20 length (center to center)

[0067] 22 axis (center to center)

[0068] 24a tensioner force

[0069] 24b belt force

[0070] 25a tensioner torque

[0071] 25b belt torque

[0072] 26 angle (force vs. axis)

[0073] 28 arm

[0074] 30 spring

[0075] 32 first end

[0076] 34 radius

[0077] 35 protrusion

[0078] 36 torsional force

[0079] 37 recess

[0080] 38 cap

[0081] 40 fastener

[0082] 42 damping bushing unit

[0083] 44 shaft

[0084] 46 ring

[0085] 48 bore

[0086] 49 axis (bore)

[0087] 50 flange

[0088] 51 axis (base bracket)

[0089] 52 contact surface (flange)

[0090] 54 body

[0091] 56 contact surface (body)

[0092] 58 axis (damping bushing unit)

[0093] 60 diameter (body)

[0094] 62 second end

[0095] 64 initial length

[0096] 66 installed length

[0097] 68 shoulder

[0098] 70 contact surface (shoulder)

[0099] 71 damping engagement region

[0100] 72 contact surface (bore)

[0101] 73 rotational engagement region

[0102] 74 axial force

[0103] 75a upper end

[0104] 75b lower end

[0105] 76 belt force

[0106] 78 inner diameter

[0107] 80 inner collar

[0108] 82 space

[0109] 84 protrusion

[0110] 86 inner diameter

[0111] 88 outer diameter

[0112] 90 bearing

[0113] 92 plane

[0114] 94 hub load distance

[0115] 96 mounting fastener DETAILED DESCRIPTION

[0116] While the following detailed description sets forth numerous specific details, it is understood that the scope of the description of claimed is defined by the language of the claims at the end of this disclosure. The detailed description is to be interpreted as exemplifying only and not as limiting, as the description of a tensioner is not exhaustive, even if not possible, to describe every possible embodiment. Alternate embodiments will become apparent to those of ordinary skill in the art, using the disclosure, or developed through the use of the disclosure, which will remain within the scope of the claims. Additionally, any combination of the features of the various figures can be used to create additional embodiments of the disclosure. Thus, the dimensions, aspects and features of one embodiment of a tensioner can be combined with those of another embodiment of a tensioner to create a claimed embodiment.

[0117] Figure 1 A belt system 2 is shown that transmits power from an internal combustion engine to other components. Specifically, a main crank pulley 4 is connected to an output shaft of the internal combustion engine, and the main crank pulley 4 turns a belt 8. The belt 8 then drives other pulleys 6a-6c to provide power to other components, such as a compressor, a water pump, an alternator, etc. The belt 8 is typically sized to fit along the path around these pulleys 4, 6a-6c. However, to ensure that power is effectively transmitted through the belt 8, a tensioner 10 is provided to press the pulley 16 into the belt 8 to keep the belt 8 taut against the other pulleys 4, 6a-6c. Another benefit of the tensioner 10 is that it can be selectively disengaged to slacken the belt 8 and allow the belt 8 to be easily removed and replaced. Once the new belt 8 is in place, the tensioner 10 is re-engaged to keep the belt 8 taut. The tensioner 10 keeps the belt 8 taut as the various pulleys 4, 6a-6c change speed, as there is slight movement between the pulleys 4, 6a-6c, and even as the belt 8 stretches and increases in size over time.

[0118] The tensioner 10 includes a base bracket 12 that is fixed to, for example, an engine block of a vehicle. One end of an arm 28 is rotatably engaged with the base bracket 12, and a pulley 16 is rotatably engaged at an opposite end of the arm 28. Thus, the pulley 16 is free to rotate against the belt 8, and the pulley 16 and arm 28 are able to rotate about the base bracket 12. As described herein, the operable engagement between the arm 28 and the base bracket 12 presses the pulley 16 against the belt 8 to keep the belt 8 taut, and also provides a damping function to absorb any oscillations in the arm 28 or vibrations in the belt 8.

[0119] A spring forming part of the operable engagement between the forming arm 28 and the base support 12. Figure 3 30) generates torsional force ( Figure 3 (36) The torsional force generates a tensioner torque 25a to rotate the arm 28 and presses the pulley 16 into the belt 8 using a tensioner force 24a. The belt 8 resists the tensioner force 24a with an opposing belt force 24b, which applies a belt torque 25b to the operable engagement between the arm 28 and the base support 12. During operation, these forces and torques are in equilibrium, and when the forces and torques become unbalanced, the tensioner 10 functions to provide the necessary responsive force and torque, as well as damping.

[0120] The geometry of the tensioner 10 and the pulley system 2 determines these forces and torques. The center 14 of the base support 12 and the center 18 of the pulley 16 are oriented along the axis 22, and these centers 14, 18 are offset by a length 20. The belt force 24b forms an angle 26 with the axis 22. The belt torque 25b caused by the belt force 24b can be expressed as:

[0121] T b =(F b (L)(Sin(A)) (1)

[0122] Where F b Let 24b be the force applied, L be the length from center to center 20, and A be the angle 26 of the force applied 24b.

[0123] Figure 2 This is a perspective view of the tensioner 10. The base bracket 12 is fixed to the engine block or other structure, and the pulley 16 rotates freely against the belt. An arm 28 spans the base bracket 12 and the pulley 16, and the arm 28 is operably engaged with both the base bracket 12 and the pulley 16. Figure 2 The text also depicts lines AA and BB.

[0124] Figure 3 For tensioner 10 along Figure 2 The cross-sectional view is taken from line AA. Spring 30 is part of the operable engagement between arm 28 and base support 12, wherein the first end 32 of spring 30 engages arm 28, and the second end ( Figure 6A - Figure 6B 62) Engages the base bracket 12, and one or more coils of the spring 30 are spaced apart from the center 14 of the base bracket 12 by a radius 34. The spring 30 has an initial angular displacement before being installed in the tensioner 10, and the spring 30 (whether coiled or unwound) is installed and applied to the belt with different angular displacements to generate a torsional force 36. The tensioner torque T generated by the spring 30... t ( Figure 1 25a) is:

[0125] T t =(F t (R) (2)

[0126] Where F t Given a torsional force of 36 and a radius of 34, the tensioner torque T... t ( Figure 1 25a) and with torque T b ( Figure 1 25b) is in equilibrium and T t =T b In this case, equations 1 and 2 can be written as:

[0127] (F b (L)(Sin(A))=(F t (R) (3)

[0128] According to Equation 2, the tensioner torque T generated by spring 30 is... t ( Figure 1 25a) in the text can also be written as:

[0129] T t =(k t (4) (θ)

[0130] Where θ is the angular displacement of spring 30 in its coiled or uncoiled state, and k t The torsional spring constant depends on the physical properties of spring 30. As pulley 16 and arm 28 torsion around base support 12, the angular displacement θ changes, therefore, the tensioner torque T generated by spring 30... t ( Figure 1 Change 25a) in the equation. Combine equations 2 and 4 and solve for the torsional force F. t (i.e., 36) yields:

[0131] F t =((k t )(θ)) / R (5)

[0132] Therefore, the torsional force F t (i.e., 36) is a function of the angular displacement θ. As described herein, this aspect of the spring 30 is independent of the axial force generated by the spring 30, which depends on the axial displacement of the spring 30 rather than the angular displacement. Thus, the overall function of the tensioner 10 can be easily adjusted over a wider range of possibilities and with greater accuracy and precision.

[0133] at last, Figure 3A protrusion 35 of the base bracket 12 is shown extending into a recess 37 of the arm 28. The protrusion 35 is configured to contact the arm 28 at each end of the recess 37 to define a range of rotational motion between the base bracket 12 and the arm 28.

[0134] Figure 4 An isometric view of various components of the tensioner 10. A fastener 40 and a cap 38 join the pulley 16 to one end of the arm 28, with the pulley 16 being free to rotate relative to the arm 28. The opposite end of the arm 28 includes a hole 48 that has a cylindrical shape and extends along an axis 49, and the hole 48 is part of the operable interface between the arm 28, the damping bushing unit 42, and the base bracket 12. Generally, the spring 30 is disposed around the hole 48. The damping bushing unit 42 then joins the arm 28 and the base bracket 12, and the arm 28 is able to rotate about an axis 51 of the base bracket 12. Additionally, the spring 30 is compressed between the arm 28 and the base bracket 12 when the damping bushing unit 42 is joined to the base bracket 12. In this embodiment, the damping bushing unit 42 includes a pivot shaft 44 and a ring 46 positioned around the pivot shaft 44. As described herein, this tensioner 10 has fewer components, and the components work together to provide independently adjustable torsional and axial forces.

[0135] Figure 5 An isometric view of the damping bushing unit 42. As described above, the damping bushing unit 42 has a pivot shaft 44 with a ring 46 disposed around the pivot shaft 44. For this arrangement, the pivot shaft 44 can be made of a sufficiently strong, dense material, or have other properties that make the pivot shaft 44 suitable to provide structure for the damping bushing unit 42. The ring 46 can then be made of a material that is optionally different from the material of the pivot shaft 44, to be more suitable for frictional engagement with other components that enable the various functions described herein. In some embodiments, the ring 46 can be a plastic material overmolded onto a metal pivot shaft 44. However, it should be understood that the present disclosure encompasses embodiments in which the damping bushing unit 42 is a single structure made of a single material, such as plastic. Optionally, the components 44, 46 can be aluminum, another metal, carbon fiber, another composite material, Teflon®, etc.

[0136] Generally, the damping bushing unit 42 includes a flange 50 and a body 54, where the outer diameter of the flange 50 is greater than the outer diameter of the body 54, and the length of the flange 50 along the axis 58 is less than the length of the body 54, although the damping bushing unit 42 need not be limited to these relationships. The flange 50 has one contact surface 52 that engages a shoulder of the arm, and the body 54 has another contact surface 56 that engages a bore of the arm. These contact surfaces 52, 56 have different orientations. In this embodiment, the contact surface 52 on the underside of the flange 50 has a planar shape that is oriented generally perpendicular to the axis 58 of the damping bushing unit 42, and the contact surface 56 has a cylindrical shape centered about the axis 58 and can be described as oriented parallel to the axis 58.

[0137] The axis 58 of the damping bushing unit 42, the axis of the bore of the arm (49 in Figure 4 ), and the axis of the base bracket (51 in Figure 4 ) are generally collinear. However, over time, wear can occur to the components, and then the axis of the arm (49 in Figure 4 ) can be forced to tilt, thereby coming out of alignment with the axis of the base bracket (51) and the axis 58 of the damping bushing unit 42. The arrangement of the components of the tensioner of the present disclosure that acts to resist this tilting will be described in more detail herein.

[0138] Figure 6A and Figure 6B show the spring 30 in an uncompressed state and a compressed state, respectively. The spring 30 extends from a first end 32 to a second end 62. In Figure 6A , the spring 30 is uncompressed and has an initial length 64. In Figure 6B , the spring 30 is compressed to an installed length 66, or to a length of the spring 30 after it is installed such that the first end 32 engages the arm (28 in Figure 1 ) and the second end 62 engages the base bracket (12 in Figure 1 ). In some embodiments, the engagement is the first end 32 contacting a stop or other similar structure of the arm, and the second end 62 contacting a stop or other similar structure of the base bracket. In the compressed state, the spring 30 generates an axial force F a :

[0139] F a = (k a )( ΔL) (6)

[0140] where k a is an axial spring constant that depends on the physical properties of the spring 30, and ΔL is the change in length of the spring 30, or the difference between the uncompressed length 64 and the compressed length 66. As described herein, the axial force F aThe change depends on the change in the length of spring 30, and the change in length is related to the torsional force F, which depends on the change in angular displacement θ. t The change is irrelevant.

[0141] Spring 30 can be more broadly described as a biasing member, which may include, but is not limited to, other solid structures, air bladders, leaf springs, coil springs, hydraulic systems, pneumatic systems, etc. Furthermore, although spring 30 has a helical shape from the first end 32 to the second end 62, this disclosure covers embodiments with other shapes. For example, spring 30 may terminate at either end 32, 62 in a loop or annulus, wherein the loop or annulus is perpendicular to one or more axes described herein. Figure 4 49 and 51 in the middle; Figure 5 58) Oriented to more evenly transmit force to the arm ( Figure 1 28) and / or base support ( Figure 1 (12) Furthermore, in various embodiments, the spring 30 has a linear response to displacement in the axial and / or angular directions, and / or the spring 30 has a nonlinear response to displacement in the axial and / or angular directions.

[0142] Figure 7 Along the operable engagement between arm 28, damping bushing unit 42 and base support 12 Figure 2 A cross-sectional view taken from line BB shows that the operable engagement provides torque and force to maintain belt tension and dampen vibration. Spring 30 is disposed between base bracket 12 and arm 28. Damping bushing unit 42 is then connected to base bracket 12 to hold the component in place. Figure 7 In the arrangement shown, due to the axial compression of the spring 30, the spring 30 generates an axial force 74, which drives the shoulder 68 of the arm 28 into the flange 50 of the damping bushing unit 42. Therefore, the contact surface 70 of the shoulder 68 engages the contact surface 52 of the flange 50 in the damping engagement region 71, and this engagement provides a damping function for the tensioner.

[0143] The damping engagement region 71 is centered on the axes 49, 51, and 58 of the bore 48, base support 12, and damping bushing unit 42, and has a planar annular shape similar to a washer. Furthermore, the planar shape of the damping engagement region 71 is oriented approximately perpendicular to the axes 49, 51, and 58 to provide several advantages of this disclosure, including preventing the arm 28 from tilting. During operation, the friction between the contact surfaces 52 and 70 in the damping engagement region 71 is enhanced by an axial force 74 to prevent movement of the arm 28 relative to the base support 12 and to absorb vibrations in the belt. In various embodiments, the axial force 74 is approximately 500 N to 3,000 N. In some embodiments, the axial force 74 is approximately 1,000 N.

[0144] Next, the contact surface 56 of the body 54 of the damping bushing unit 42 and the contact surface 72 of the bore 48 of the arm 28 selectively engage with each other in a rotational engagement region 73 to help limit the movement of the arm 28 relative to the base support 12 to rotational motion. This rotational engagement region 73 has a cylindrical shape centered on axes 49, 51, 58, and can therefore be described as parallel to axes 49, 51, 58. The dimensions of these contact surfaces 56, 72 can be set to have a relatively small gap between them, which allows the arm 28 to rotate about the base support 12 while minimizing the amount of tilt of the arm 28 relative to the base support 12 in the presence of forces that would cause the arm 28 to disalign with the base support 12. This gap can be defined as the inner diameter 78 defined by the contact surface 72 of the bore 48 of the arm 28 and the contact surface 72 of the body 54 of the damping bushing unit 42. Figure 5 The outer diameter of 54 in the middle ( Figure 5 The difference between 60 and 60.

[0145] By utilizing independent damping and rotational engagement regions 71 and 73, the tensioner 10 can have independently adjustable axial and torsional forces, making the adjustment of the tensioner 10's function much easier than in prior art designs. Furthermore, the rotational engagement region 73 can optionally contribute to the damping effect of the tensioner depending on the size of the gap between the damping bushing unit 42 and the hole 48. In cases of small or even no gap, and with materials having a high coefficient of friction, the engagement between the contact surfaces 56 and 72 in the rotational engagement region 73 can prevent rotational movement of the arm 28 relative to the base support 12 and contribute to the damping effect.

[0146] Figure 7 The belt force 76 caused by the engagement between the pulley and the belt is also depicted. This belt force 76 is generally the source of wear on the arm 28 and the tilting of the arm 28 relative to the base support 12, and the arm 28 is forced to tilt about the belt force 76. In some embodiments, Figure 7 The belt force 76 described herein may be the same belt force described elsewhere in this document. Figure 1 (24b in the example). In various embodiments, Figure 7 The force 76 described herein can be the force described elsewhere in this text. Figure 1 The component of 24b) (alone or in combination with other forces). In some embodiments, the applied force 76 is less than about 500 N.

[0147] The relative positions of the engagement regions 71 and 73 help prevent tilting of the arm 28. Specifically, a separate damping engagement region 71, having a different shape from the rotary engagement region 73 (which extends further in the lateral direction than the rotary engagement region 73), helps restrain the movement of the arm 28 and prevent tilting. Furthermore, as the axial force 74 drives the shoulder 68 into the flange 50, the axial force 74 and the damping engagement region 71 keep the arm 28 aligned with the damping bushing unit 42 and the base support 12 to reduce tilting and uneven wear of the tensioner components. Additionally, the axial force 74 can be greater than the belt force 76 to prevent tilting and keep the arm 28 aligned with the damping bushing unit 42 and the base support 12. In some embodiments, the axial force 74 is approximately three times the belt force 76.

[0148] Furthermore, when the damping engagement region 71, which generates the damping effect, is positioned away from the rotation engagement region 73, the contact surface 56 of the body 54 of the damping bushing unit 42 and the contact surface 72 of the hole 48 of the arm 28 are generally less prone to wear, and uneven wear is also less likely to occur. Therefore, the tensioner of this disclosure has less tilt and a longer service life.

[0149] Figure 8 Also along the operable engagement between arm 28 and base support 12 Figure 2 The figure shows a cross-sectional view taken from line BB. Here, the damping bushing unit 42 is connected to the base support 12 to compress the spring 30 and hold other components, as shown. The damping bushing unit 42 has a body 48 and a downwardly extending collar 80 to define an annular space 82 between them. The base support 12 includes a cylindrical protrusion 84 that extends upward and is configured to press into the space 82 with an interference fit strong enough to resist any axial force generated by the spring 30 or any other force that the tensioner may experience during operation. In some embodiments, as the protrusion 84 extends upward, it tapers to a smaller diameter, and the annular space 82 has a corresponding taper to help center the damping bushing unit 42 on the base support 12.

[0150] Figure 9 A cross-sectional view showing one embodiment of the tensioner 10. The flange of the damping bushing unit 42 ( Figure 7 The contact surface of 50 in the middle ( Figure 7 52 in the middle) and shoulder of arm 28 ( Figure 7 The contact surface of 68 in the middle ( Figure 7 The damping engagement region 71 between the bore 48, base support 12, and damping bushing unit 42 extends between the inner diameter 86 and the outer diameter 88, surrounding the axes 49, 51, and 58 of the bore 48, base support 12, and damping bushing unit 42. Using these diameters 86 and 88, the damping torque for the movement of the stop arm 28 can be calculated as follows:

[0151] T d =(F a (D) i + D o (μ) / 2 (7)

[0152] Where F a The axial force 74, D generated by spring 30 i The inner diameter of the damping joint region 71 is 86, D o The outer diameter 88 of the damping engagement region 71 is given by μ, which depends on the contact surface in the damping engagement region 71. Figure 7 The coefficient of friction of the materials (52, 70) in the model is also considered. Furthermore, the radius 34 of the spring 30 is a predetermined distance from axes 49, 51, 58, and determines the position where the axial force 74 presses the arm 28 into the damping bushing unit 42. In some embodiments, the axial force 74 is guided through the contact surface (…). Figure 7 The damping engagement region 71 (52, 70) is designed to maintain a uniform distribution of any wear in the damping engagement region 71. In other words, the radius 34 is less than half the outer diameter 88 and greater than half the inner diameter 86. Alternatively, the diameter of the spring 30 (twice the radius 34) is less than the outer diameter 88 and greater than the inner diameter 86.

[0153] Figure 9 Also shown is a pulley 16 rotatable about a set of bearings 90 aligned in a plane 92, which determines the position where the force 76 causes the arm 28 to tilt. This plane 92 is offset axially relative to the damping engagement region 71 by an offset distance 94. Therefore, the damping engagement region 71, buttressed laterally by the axial force 74, helps constrain the movement of the arm 28 and prevents it from tilting.

[0154] The arrangement of the force-applying zone 76 and the rotational engagement zone 73 also helps to prevent the arm 28 from tilting. The plane 92 and the force-applying zone 76 extend through the contact surface of the body of the damping bushing unit 42. Figure 7 The contact surface between 56 in the middle and the hole in arm 28 ( Figure 7 The rotational engagement region 73 between the upper end 75a and the lower end 75b of the rotational engagement region 73 extends specifically through the area between the upper end 75a and the lower end 75b of the rotational engagement region 73. This, on the one hand, makes the contact surfaces ( Figure 7 (56, 72) Maintaining balance reduces wear, helps to keep any wear essentially uniform, and reduces tilting of arm 28 relative to base support 12, because both the portion of rotary engagement region 73 above the belt force 76 and the portion of rotary engagement region 73 below the belt force 76 can prevent tilting. Based on these defined aspects, the anti-tilting effect of the arrangement according to this disclosure can be expressed as a dimensionless ratio:

[0155] Anti-tip effect = ((F a )(D i + D o )) / (4(F b )(L o )) (8)

[0156] where F a is the axial force 74 generated by the spring 30, D i is the inner diameter 86, D o is the outer diameter 88, F b is the belt force 76, and L o is the offset 94 between the bearing plane 92 and the damping interface region 71. Prior art tensioners have small diameters 86, 88 and no axial force 74, and thus have a small anti-tip effect.

[0157] Figure 9 and Figure 10 An alternate embodiment is shown for mounting the damping bushing unit 42 to the base bracket 12. In Figure 9 , a mounting fastener 96 extends through the damping bushing unit 42 and into the base bracket 12. In Figure 10 , the damping bushing unit 42 is press fit into the base bracket 12, and the shaft 44 of the damping bushing unit 42 extends to the bottom surface of the base bracket 12.

[0158] While various embodiments of the present disclosure have been described in detail, it should be apparent that modifications and variations to those embodiments could be made by those skilled in the art without departing from the scope and spirit of the disclosure, which is described in the appended claims. Furthermore, the described invention(s) can be implemented or carried out in other ways than those specifically described herein without departing from the scope and spirit of the present disclosure. It is therefore contemplated to be within the scope of the present disclosure to carry out or carry out the present disclosure in other specific ways not specifically described herein. It is also to be understood that the terminology and phraseology used herein is solely used for descriptive purposes and should not be viewed as limiting.

Claims

1. A tensioner for a belt, comprising: an arm configured to rotate about an axis of a base bracket, the arm having a bore and a shoulder; a biasing member extending from a first end to a second end, wherein the first end is engaged with the arm and the second end is engaged with the base bracket; and a damping bushing unit joined with the base bracket and at least partially positioned in the bore of the arm, wherein the shoulder of the arm and a flange of the damping bushing unit are configured to engage each other in a damping engagement region, and the biasing member is configured to drive the shoulder of the arm into the flange of the damping bushing unit in a direction parallel to the axis of the base bracket to generate a damping torque in the damping engagement region.

2. The tensioner of claim 1, further comprising: a body of the damping bushing unit configured to engage the bore of the arm in a rotational engagement region to allow the arm to rotate about the base bracket.

3. The tensioner of claim 2 wherein, the damping engagement region has a planar shape generally perpendicular to the axis of the base bracket, and the rotational engagement region has a cylindrical shape generally centered about the axis of the base bracket.

4. The tensioner of claim 1, wherein, the damping bushing unit comprises: a shaft made of a first material; and a ring disposed about at least a portion of an outer surface of the shaft, wherein the ring is made of a second material different from the first material.

5. The tensioner of claim 1, wherein, the damping bushing unit is a single continuous structure made of a plastic material.

6. The tensioner of claim 1, wherein, a lower end of the damping bushing unit comprises an annular recess, and the base bracket comprises a cylindrical protrusion, wherein the protrusion is configured to press fit into the recess to join the damping bushing unit with the base bracket.

7. The tensioner of claim 1, wherein, a mounting fastener extends through a threaded hole of the damping bushing unit and into a threaded portion of the base bracket to join the damping bushing unit with the base bracket.

8. A tensioner for a belt, comprising: an arm configured to rotate about an axis of a base bracket, the arm having a bore and a shoulder; a damping bushing unit joined with the base bracket and at least partially positioned in the bore of the arm, wherein the shoulder of the arm and a flange of the damping bushing unit are configured to engage each other in a damping engagement region, and a body of the damping bushing unit is configured to engage the bore of the arm in a rotational engagement region to allow the arm to rotate about the axis of the base bracket; and wherein the damping engagement region has a planar shape generally perpendicular to the axis of the base bracket, and the rotational engagement region has a cylindrical shape generally centered about the axis of the base bracket.

9. The tensioner of claim 8, further comprising: a pulley rotatably engaged with the arm and configured to press into a belt, wherein the pulley comprises a plurality of bearings oriented in a plane generally parallel to the damping engagement region.

10. The tensioner of claim 9, wherein, the plane extends through the rotational engagement region.

11. The tensioner of claim 9, wherein, the plane is offset from the damping engagement region by a predetermined distance.

12. The tensioner of claim 8, further comprising: a biasing member extending from a first end to a second end, wherein the first end is engaged with the arm and the second end is engaged with the base support, wherein the biasing member is configured to drive a shoulder of the arm into a flange of the damping bushing unit in a direction parallel to the axis to generate a damping torque in the damping engagement region, and wherein a diameter of the biasing member is less than an outer diameter of the damping engagement region and greater than an inner diameter of the damping engagement region.

13. The tensioner of claim 8, wherein, a body of the damping bushing unit extends downward from the flange such that the damping engagement region is located near an upper end of the rotational engagement region.

14. The tensioner of claim 8, wherein, the biasing member is a coil spring disposed around the bore of the arm and the body of the damping bushing unit.

15. A tensioner for a belt, comprising: an arm configured to rotate about an axis of a base support; a damping bushing unit coupled with the base support, wherein the damping bushing unit fixes the arm to the base support; and a spring extending between a first end engaged with the arm and a second end engaged with the base support, wherein the spring is configured to exert a torsional force in response to an angular displacement of the spring between the arm and the base support, and the spring is configured to exert an axial force in response to an axial displacement of the spring between the arm and the damping bushing unit, wherein the torsional force and the axial force are independently adjustable.

16. The tensioner of claim 15, further comprising: a pulley rotatably engaged with the arm and configured to press into a belt, wherein the pulley includes a plurality of bearings oriented in a plane generally parallel to a damping engagement region in which a shoulder of the arm and a flange of the damping bushing unit are configured to engage one another, wherein the axial force generates a damping torque in the damping engagement region.

17. The tensioner of claim 16, wherein, the plane extends through a rotational engagement region in which a bore of the arm and a body of the damping bushing unit are configured to engage one another to permit the arm to rotate about the base support.

18. The tensioner of claim 17, wherein, the damping engagement region has a planar shape generally perpendicular to the axis of the base support, and the rotational engagement region has a cylindrical shape generally centered about the axis of the base support.

19. The tensioner of claim 17, wherein, the body of the damping bushing unit extends downward from the flange such that the damping engagement region is located near an upper end of the rotational engagement region.

20. The tensioner of claim 16, wherein, a diameter of the spring is less than an outer diameter of the damping engagement region and greater than an inner diameter of the damping engagement region.

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