WO2021243049A1

WO2021243049A1 - Belt tensioner

Info

Publication number: WO2021243049A1
Application number: PCT/US2021/034566
Authority: WO
Inventors: Yahya Hodjat; Marc Cadarette; Devang Sisodia; Dhanaraj JAGATHEESH
Original assignee: Gates Corporation
Priority date: 2020-05-29
Filing date: 2021-05-27
Publication date: 2021-12-02

Abstract

The present invention relates to a tensioner (100, 300). The tensioner (100, 300) comprises a cantilever spring (102, 302) having a first arm (104, 304) and a second arm (106, 306), a pulley (110, 310) journalled to the tensioner (100, 300), and a mounting portion (108, 308). In a first embodiment, a frictional damping member (114) comprising a first damping plate (116) and a pair of second damping plates (118) is positioned between the first arm (104) and the second arm (106) for damping vibrations in the cantilever spring (102). In a second embodiment, a resilient damping spring (314) having an arcuate profile is positioned between the first arm (304) and the second arm (306) for damping vibrations in the cantilever spring (302).

Description

BELT TENSIONER

TECHNICAL FIELD

[0001] The present invention relates to tensioners for belt drive systems, and more particularly to a tensioner having a cantilever spring and a resilient damping member engaged with the cantilever spring.

BACKGROUND OF THE INVENTION

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] A drive belt is used for transferring motion from a driving part to a driven part, such as to transfer motion from a motor or an engine to other part(s) of a vehicle. Over a period of time, the belt slacks, and vibrations get introduced in a motion transfer system utilizing the belt. Such vibrations could damage the motion transfer system. In order to prevent the vibrations from being produced in the motion transfer system, a tensioner is typically required to ensure that the belt is kept under a suitable amount of tension. During an operation, variable amount of power is generated and required to be transferred by the motion transfer system. The tensioner is required to utilize suitable mechanisms to absorb such variations in power.

[0004] Efforts have been made in the past to develop tensioners that are capable of driving accessories with varying amounts of power. For example, U. S. Pat. Pub. No. 2009/0118045A1 discloses a tensioner having a cantilever spring including a first arm and a second arm. A resilient damping member is disposed between the first arm and the second arm for damping arm vibrations. The damping member is made using natural rubber, synthetic rubber, or a combination of the two. Natural rubber or synthetic rubber offers slow response for damping vibrations in the tensioner, and therefore hamper performance characteristics of the tensioner.

[0005] There is therefore a need to develop a tensioner which is capable of eliminating the deficiencies associated with conventional tensioners, specifically the slow damping response. OBJECTS OF THE INVENTION

[0006] It is an object of the present invention to provide a tensioner for a belt drive system that is capable of driving various accessories of a vehicle.

[0007] It is another object of the present invention to provide a tensioner that is capable of exhibiting improved damping response compared to a conventional tensioner.

[0008] It is another obj ect of the present invention to provide a tensioner having a damping member that reduces vibrations during operation of the tensioner, thereby prolonging life of the tensioner.

[0009] It is yet another object of the present invention to provide a tensioner having modular components.

[00010] It is still another obj ect of the present invention to provide a tensioner that could be retrofitted in typical belt drive systems.

SUMMARY OF THE INVENTION

[00011] The present invention relates to a tensioner for a belt drive system used for driving various accessories of a vehicle with varying power requirements. The tensioner employs a damping member for efficiently reducing vibrations during operation. Further, the tensioner described in present invention exhibits improved damping response compared to conventional tensioners.

[00012] In one embodiment, the tensioner described in current disclosure includes a cantilever spring having a first arm and a second arm. The first arm and the second arm describe a first predefined angle which may be an acute angle. The tensioner further includes a pulley journalled to the first arm, a mounting portion, and a frictional damping member. The frictional damping member is disposed between the first arm and the second arm to damp vibrations of the cantilever spring. The frictional damping member comprises a first damping plate and a pair of second damping plates. Outer ends of the first damping plate are affixed to the first arm and outer ends of the pair of second damping plates are affixed to the second arm. Further, portions of the pair of second damping plates are in relation to portions of the first damping plate at a second predefined angle.

[00013] The pair of second damping plates make sliding contact on side surfaces of the first damping plate through a damping material on the side surfaces of the first damping plate. The damping material may be a pair of damping bands made of plastic or metal plates over-molded with plastic having a desired frictional characteristic. In some implementations, the frictional damping member could be encased within an enclosure.

[00014] In another embodiment, the tensioner described in current disclosure includes a cantilever spring having a first arm and a second arm. The first arm and the second arm describe a first predefined angle which may be an acute angle. The tensioner further includes a pulley journalled to the first arm, a mounting portion, and a resilient damping spring. The resilient damping spring is disposed between the first arm and the second arm to damp vibrations of the cantilever spring. The resilient damping spring includes a first end affixed to the first arm and a second end affixed to the second arm. The resilient damping spring has an arcuate profile along the first predefined angle. Further, the resilient damping spring could be metal with at least a portion thereof coated with a resilient damping material. The resilient damping material may be one of a special plastic and an elastomer.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[00015] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[00016] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. [00017] Fig. 1 illustrates a perspective front view of a tensioner, in accordance with an embodiment of the present invention;

[00018] Figs. 2A and 2B illustrate perspective front views of the tensioner using an enclosure, in accordance with an embodiment of the present invention; and

[00019] Fig. 3 illustrates a perspective front view of a tensioner, in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[00020] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[00021] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[00022] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[00023] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. [00024] In some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[00025] The present invention relates to a tensioner for a belt drive system having a cantilever spring and a damping member engaged with the cantilever spring for damping vibrations generated during operation of the tensioner so as to improve performance characteristics and prolong life of the tensioner, even in cases of transfer of dynamic belt loads to the cantilever spring.

[00026] Fig. 1 illustrates a perspective front view of a tensioner 100, in accordance with an embodiment of the present invention. The tensioner 100 includes a cantilever spring 102 having a first arm 104, a second arm 106, and a mounting portion 108. A pulley 110 may be journalled to the first arm 104. Further, the pulley 110 may be an idler pulley used in a drive belt system to maintain a desired tension of the belt during operation of the drive belt system. The belt may have a multi-ribbed profile for improving grip of the belt over the pulley 110.

[00027] The first arm 104 and the second arm 106 may describe a first predefined angle. The first predefined angle may have a value ranging between 30° and 150°, or may be an acute angle (having value less than 90°), or preferably in the range 40° to 50° in different implementations. Further, as illustrated in Fig. 1, it should be understood that an area of contact of the first arm 104 and the second arm 106 may include gradual bending of material instead of a sharp bend.

[00028] In one implementation, the first arm 104 and the second arm 106 may form together a “V” shape or a “U” shape. In certain implementations, the cantilever spring 102 may have a “W” shape or other desired shapes when other arms are present in addition to the first arm 104 and the second arm 106. Further, the first arm 104 and the second arm 106 may be made up of a flat metal strip having a desired spring rate.

[00029] In one implementation, the mounting portion 108 may indicate an end portion of the second arm 106. The mounting portion 108 may be affixed on a rigid surface of a machinery utilizing a belt drive system. The mounting portion 108 may be affixed using a suitable mechanism such as through welding, nuts and bolts, screws, studs, and pins. One or more apertures 112 may be present on the mounting portion 108 for receiving the nuts and bolts, screws, studs, and dowel pins.

[00030] A frictional damping member 114 is disposed between the first arm 104 and the second arm 106. The frictional damping member 114 may include a first damping plate 116 and a pair of second damping plates 118. Outer ends of the first damping plate 116 may be affixed to the first arm 104 and outer ends of the pair of second damping plates 118 may be affixed to the second arm 106. For affixing the outer ends of the first damping plate 116 and the outer ends of the pair of second damping plates 118 with the first arm 104 the second arm 106 respectively, suitable techniques such as fastening, welding, or adhesion may be utilized. Further, an inner portion of the pair of second damping plates 118 may be present in contact with a portion of the first damping plate 116 at a second predefined angle. The second predefined angle may range from 40° to 180°, in different implementations. Specifically, each plate of the pair of second damping plates 118 may make contact on side surfaces, such as external side surfaces, of the first damping plate 116. In this frictional damping case, the contact made between the pair of second damping plates 118 and the first damping plate 116 is slidable in nature. The plates may be attached to the respective arms (104, 106) by any mechanical means or welding means desired. Frictional damping is achieved by plates 116 and 118 sliding on each other. Damping material (generally a specially formulated plastic) is commonly applied on or attached to one or the other surfaces of the damping plates, while the other of the plates is metal. Thus, the damping material 120 may attached to the first damping plate 116 as shown in FIG. 1 and the second damping plates 118 may be metal. Alternately, damping plate 116 may be integrally formed of damping material 120. Alternately, damping plate 116 may be metal and damping material 120 may be applied to the contact surfaces of second damping plates 118.

[00031] The tensioner 100 may apply load on the belt moving over the pulley 110. The belt load is realized through compression of the cantilever spring 102. A magnitude of the belt load is a function of several factors including a spring rate of the cantilever spring 102, the first predefined angle present between the first arm 104 and the second arm 106, and a position of placement of the mounting portion 108.

[00032] During an operation, the cantilever spring 102 may experience variable compression loads due to slackening of the belt moving over the pulley 110. Because the second arm 106 is rigidly fixed at the mounting portion 108 and the first arm 104 is movable, the variable compression loads would result into movement of the first arm 104 towards and/or away from the second arm 106. When such movements of the first arm 104 become frequent, vibrations would be produced in the tensioner 100. The frictional damping member 114 functions to damp such vibrations. Upon movement, the first arm 104 may apply pressure on the first damping plate 116. Such pressure would cause movement of the first damping plate 116 along points of contact present with the pair of second damping plates 118 which may also lead to change in the second predefined angle. Thereupon, the friction between first damping plate 116 and the pair of second damping plates 118 would oppose to such motion between them, and a counterforce may get applied by the first damping plate 116 on the first arm 104. Such counterforce would result in damping of the vibrations. To obtain required damping effects, the pair of second damping plates 118 and the first damping plate 116 may be made of special plastics and metals having suitable frictional damping characteristics when sliding against each other. The components of the frictional damping member 114 may be typically sized to properly damp vibrations without unduly affecting a spring rate of the cantilever spring 102. The spring rate of cantilever spring 102 may be in the range of approximately 0.1 or 0.25 Nm/degree up to 2 or 3 Nm/degree, preferably less than 1.0 Nm/degree, to provide a desired belt tension control in an application.

[00033] In various implementations, a damping material, such as a pair of damping bands 120, may be over-molded on the side surfaces of the first damping plate 116, i.e., one damping band may be over-molded on each side surface of the first damping plate 116. The pair of damping bands 120 may be over-molded on the side surfaces of the first damping plate 116 during manufacturing of the first damping plate 116. Alternatively, the pair of damping bands 120 may be adhered to the side surfaces of the first damping plate 116 by over-molding, mechanical fasteners, or using suitable adhesives. Further, the pair of damping bands 120 may be made up of plastic or metal plates over-molded with plastic having a desired frictional characteristic. [00034] With usage of the first damping plate 116 over-molded with the pair of damping bands 120, the pair of second damping plates 118 may make contact on the side surfaces of the first damping plate 116 through the pair of damping bands 120. Alternately, as mentioned above, the location of the damping bands 120 and metal component may be reversed. With either arrangement, the pair of damping bands 120 will prevent direct metal-on-metal contact, thereby preventing generation of noise and heat, and damage of material during operation of the tensioner 100.

[00035] Fig. 2A illustrates a perspective front view of the tensioner 100 comprising an enclosure 202, in accordance with an embodiment of the present invention. The enclosure 202 may cover a portion of the frictional damping member 114. As illustrated in Fig. 2A, the enclosure 202 may cover the damping plate 116, the pair of damping bands 120, and an area of contact between the first damping plate 116, the pair of second damping plates 118, and the pair of damping bands 120. The enclosure 202 may be joined over a surface of the first arm 104 using suitable means such as adhesives, connectors, nuts and bolts, and screws. The enclosure 202 may be made up of a material having excellent water-resistant and dust-resistant property, such as any rubber (such as silicone, Ethylene Propylene Diene Monomer (EPDM), Acrylonitrile Butadiene Rubber (NBR), Natural Rubber (NR), neoprene (CR), Styrene- Butadiene Rubber (SBR), and the like), thermoplastic elastomer, and/or plastic. The enclosure 202 may prevent exposure of the frictional damping member 114 to external environmental agents, such as dust and water. The enclosure could be an elastomer tube/sheet with heat-shrink properties for ease of installation and lower cost.

[00036] Fig. 2B illustrates a perspective front view of the tensioner 100 comprising an enclosure 204, in accordance with an embodiment of the present invention. As illustrated in Fig. 2B, the enclosure 204 may cover the frictional damping member 114 completely. The enclosure 204 may be joined over surfaces of the first arm 104 and the second arm 106 using suitable means such as heat shrinking, adhesives, connectors, nuts and bolts, and screws. The enclosure 204 may be made up of a material having excellent water-resistant and dust-resistant property. Additionally, a flexible material such as rubber, thermoplastic elastomer, or plastic may be used to fabricate the enclosure 204 for withstanding changes in distance between the first arm 104 and the second arm 106. The material of enclosure 204 may be corrugated or hinged for flexibility. [00037] Fig. 3 illustrates a perspective front view of a tensioner 300 (similar to the tensioner 100), in accordance with a second embodiment of the present invention. The tensioner 300 includes a cantilever spring 302 (similar to the cantilever spring 102) having a first arm 304 (similar to the first arm 104), a second arm 306 (similar to the second arm 106), and a mounting portion 308 (similar to the mounting portion 108). A pulley 310 (similar to the pulley 110) may be journalled to the first arm 304. The mounting portion 308 may include one or more apertures 312 (similar to the one or more apertures 112). It must be understood that structural and functional aspects of the tensioner 300 and its components are similar to the tensioner 100 and its corresponding components.

[00038] A resilient damping member, specifically, a resilient damping spring 314 is disposed between the first arm 304 and the second arm 306. The resilient damping spring 314 includes a first end 316 and a second end 318. The first end 316 may be affixed to the first arm 304 and the second end 318 may be affixed to the second arm 306. For affixing the first end 316 and a second end 318 with the first arm 304 the second arm 306 respectively, suitable techniques such as fastening, welding, or adhesion may be utilized. The resilient damping spring 314 has an arcuate profile along a first predefined angle defined between the first arm 304 and the second arm 306.

[00039] During an operation, when vibrations are caused in the tensioner 300, the resilient damping spring 314 functions to damp the vibrations. The resilient damping spring 314 would oppose to inward movement of the first arm 304 caused during the vibrations. To obtain required damping effects, type of metal and thickness of the metal used for fabricating the resilient damping spring 314 may be selected appropriately. The resilient damping spring 314 may be typically sized to properly damp vibrations without unduly affecting a spring rate of the cantilever spring 302. The spring rate of cantilever spring 302 is in the range of approximately 0.25 Nm/degree up to 2 Nm/degree. The spring rate of resilient damping spring 314 is relatively light, or much lower than that of cantilever spring 302.

[00040] In some implementations, the metal of resilient damping spring 314 may be partially or completely over-molded, adhered, or coated with a resilient damping material 320. The resilient damping material 320 may improve damping characteristics of the resilient damping spring 314 and/or prevent degradation of material of the resilient damping spring 314 by environment agents, such as dust and water. The resilient damping material 320 may be any suitable plastic or elastomer. For example, materials such as Hydrogenated Acrylonitrile Butadiene Rubber (HNBR), EPDM, NR, CR, and SBR, or blends thereof, formulated with various known rubber ingredients, may be used as the resilient damping material 320. In some implementations, more than one layer of metal and/or damping material may be utilized to form the resilient damping spring 314. The thicknesses, shapes, and material properties of the metal(s) and damping material coating(s) may be optimized to achieve a desired level of damping. The resilient damping spring may thus function as a constrained-layer damper. The spring shape could be like a leaf spring, a coil spring, or other desired shape.

[00041] It should also be noted that the resilient damping element of the second embodiment has no moving parts and thus may not require any protective enclosure. The second embodiment may also be a lower cost alternative compared to the first embodiment. Furthermore, the resilient damping element of the second embodiment is not subject to wearing out like the frictional damping element of the first embodiment.

[00042] The tensioners described in above provided embodiments include low-cost modular components which may be manufactured in a transfer press in one press hit. Conventional aluminium die cast housings for the tensioner components, are not needed according to the present invention. The cantilever spring may be coated or plated by any desired industrial coatings such as electrodeposition (E-Coating), plating, etc. to prevent rust or corrosion.

[00043] Although a form of the invention has been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts and method without departing from the spirit and scope of the invention described herein. While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.

Claims

We Claim:

1. A tensioner (100) comprising: a cantilever spring (102) having a first arm (104) and a second arm (106), the first arm (104) and the second arm (106) describing a first predefined angle; a pulley (110) journalled to the first arm (104); a mounting portion (108); and a frictional damping member (114) disposed between the first arm (104) and the second arm (106) to damp vibrations of the cantilever spring (102), wherein the frictional damping member (114) comprises a first damping plate (116) and a pair of second damping plates (118), wherein outer ends of the first damping plate (116) are affixed to the first arm (104) and outer ends of the pair of second damping plates (118) are affixed to the second arm (106), and inner portions of the pair of second damping plates (118) are in sliding contact with corresponding portions of the first damping plate (116) at a second predefined angle.

2. The tensioner (100) as claimed in claim 1, wherein the pair of second damping plates (118) make said sliding contact on side surfaces of the first damping plate (116) through a pair of damping bands (120) over-molded on the side surfaces of the first damping plate (116).

3. The tensioner (100) as claimed in claim 2, wherein the pair of damping bands (120) comprise plastic or metal plates over-molded with plastic.

4. The tensioner (100) as claimed in claim 1, wherein the pair of second damping plates (118) make said sliding contact on side surfaces of the first damping plate (116) through a pair of damping bands (120) over-molded on the inner portions of the second damping plates (118).

5. The tensioner (100) as claimed in claim 4, wherein the pair of damping bands (120) comprise plastic or metal plates over-molded with plastic.

6. The tensioner (100) as claimed in claim 1, wherein the frictional damping member (114) is encased within an enclosure (202, 204).

7. A tensioner (300) comprising: a cantilever spring (302) having a first arm (304) and a second arm (306), the first arm (304) and the second arm (306) describing a first predefined angle; a pulley (310) journalled to the first arm (304); a mounting portion (308); and a resilient damping spring (314) disposed between the first arm (304) and the second arm (306) to damp vibrations of the cantilever spring (302), wherein the resilient damping spring (314) includes a first end (316) affixed to the first arm (304) and a second end (318) affixed to the second arm (306).

8. The tensioner (300) as claimed in claim 7, wherein the resilient damping spring (314) comprises an arcuate profile along the first predefined angle.

9. The tensioner (300) as claimed in claim 7, wherein the resilient damping spring (314) comprises metal coated with a resilient damping material (320).

10. The tensioner (300) as claimed in claim 9, wherein the resilient damping material (320) comprises a plastic or an elastomer.

11. The tensioner (300) as claimed in claim 9, wherein the resilient damping spring (314) is not encased within an enclosure.

12. The tensioner (100, 300) as claimed in claim 1, wherein the first predefined angle is an acute angle.

13. The tensioner (100, 300) as claimed in claim 7, wherein the first predefined angle is an acute angle.