EP0643810A4

EP0643810A4 - Endless flexible drive belt.

Info

Publication number: EP0643810A4
Application number: EP92912693A
Authority: EP
Inventors: Donald Dekle Bartholomew
Original assignee: Proprietary Technology Inc
Current assignee: Proprietary Technology Inc
Priority date: 1992-05-18
Filing date: 1992-05-18
Publication date: 1995-08-02
Also published as: AU2141592A; CA2135185A1; AU669663B2; EP0643810A1; JPH07506891A

Abstract

A continuous belt for power transmission has a thin elongated strip (10) having a pair of ends. A serpentine biasing portion (22, 30, 32, 34) is integrally formed in the strip between the ends. Also, the ends are permanently joined with one another to provide an endless belt to transit power or torque.

Description

ENDLESS FLEXIBLE DRIVE BELT

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to drive belts and, mor particularly, to an endless or continuous drive belt with serpentine spring biasing portion.

Ordinarily, drive belts which drive rotary equipment ar either of a belt or chain type. The belt type is generall manufactured from a polymeric material with or without reinforcin filament strands. The chain type generally includes a plurality o interconnected links.

In the automotive industry, fan belts are commonly used t transmit power from an engine to various accessories such a compressors, alternators or the like. During start-up of th engine, a peak torque is required to begin to turn or rotate th belt to drive the accessories. Once the engine starts and runs the torque is reduced and less force is exerted onto the belt During the peak torque at start-up, the belt is stretched to degree that may permanently deform the belt. Ordinarily, a adjustable tensioner is utilized to take up the excessive play i the fan belt. Thus, it would be desirable to provide a continuou belt which would reduce the peak torque required by the engin without permanent deformation of the belt.

Accordingly, it is an object of the present invention t overcome the above disadvantages. The present invention provide a continuous belt with a serpentine spring biasing portion to transmit torque which is easily adapted to replace belts or chains. The present invention provides a continuous belt which has more than one mode of recoverable deformation to enable the belt to first elongate in response to a large force and to provide additional elongation in response to a much smaller force. This endless belt enables the engine to have a lower peak torque at start-up.

From the following description and claims, taken in conjunction with the accompanying drawings, other objects and advantages of the present invention will become apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a schematic view of driving and driven equipment including a continuous belt in accordance with the present invention.

Figure 2 is a partial perspective view of the continuous belt in accordance with the present invention.

Figure 3 is a graph of the force versus displacement of the belt in accordance with the present invention.

Figure 4 is a partial perspective view of another embodiment of a belt in accordance with the present invention.

Figure 5 is a cross section view of another belt in accordance with the present invention. Figure 6 is a cross section view of another embodiment of th present invention.

Figure 7 is a cross section view of another embodiment of th present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to the Figures, particularly Figure 1, a continuou belt is shown and designated with the reference numeral 10. Th continuous belt 10 is illustrated with a mechanism for driving th belt 12, such as an engine, and a device 14, such as a compressor, which is driven by the belt. The belt 10 is associated with th driving and driven devices via pulleys 16 and 18. Also, a bel tensioning device 20 is positioned on the return side of the bel 10 to take up slack in the belt 10.

The belt 10 is an elongated strip and may be formed from an suitable metallic sheet material having requisite strengt resilient characteristics. The belt 10 has a serpentine pattern 2 continuous throughout the belt 10 from one end to the other. Th serpentine pattern 22 includes a plurality of interconnecte unitary U-shaped members 30 having a pair of legs 32 connected b a web 34. Each alternating U-shaped member 30 is inverted wit respect to its adjacent U-shaped members 30. The U-shaped member 30 have an overall rectangular cross section with a substantiall constant thickness. A slot 36 which separates legs 32 extends fro a lateral edge of the belt inward to the web 34, a distance beyon the longitudinal axis of the belt 10. The serpentine U-shape configuration is like that disclosed in applicant's U.S. Patent No 4,919,403, issued April 24, 1990, entitled "SERPENTINE STRIP SPRING" and U.S. Patent Application Serial No. 916,155, filed October 7, 1986, entitled "SPRING", the specifications of both which are herein expressly incorporated by reference.

The belt 10 is designed such that the width of the legs 32 is generally less than the width of the webs 34 as seen in Figure 2. This provides bending across the width dimensions when longitudinal axial forces, designated by Fl and F2, are applied on the belt 10. Once the longitudinal axial forces reach a determined value, the legs 32 will begin to twist in response to additional force. This twist is the result of bending across the roots 34 of the thickness 33 of the material, referred to as "root pucker", where the deformation is along the thickness of the belt 10, and bending across the width of the legs. The forces on various portions of the belt 10 material can be determined by a finite element analysis so that the belt 10 may be designed to deform as desired in response to the applied driving and driven forces. The belt 10 may be manufactured from prehardened stainless steel and may be formed by laser or abrasive cutting techniques. Also, annealing or edge treatments may be conducted on the belt 10 by laser or other means.

Figure 3 illustrates a force versus displacement or elongation graph. As the belt 10 stretches in response to forces in the F1-F2 direction of Figure 2, a first spring constant is present and is designated with the numeral 40. As continued force is applied to the belt 10, the belt 10 begins to additionally bend across the thickness of the strip material going into the second spring constant which is designated with the reference numeral 42.

The phantom line in Figure 3 illustrates the force versus elongation graph of a currently used fan belt. The poin designated with reference letter "A" illustrates the normal runnin force that is generally applied to the belt when the drivin mechanism is continuously operating. The point "B" designates th peak force required at start-up to begin movement of the belt, an devices driven by the belt. As can be seen in the graph, the pea force in the present invention is much less than that of currentl used belts. Also, while the displacement or elongation of th present invention is more than that of currently used belts, th peak force is significantly reduced. The belt tends t individually start individual driven devices when more than on device 14 is being driven, and the elongation of the belt i controlled by the design and material of the belt 10.

Returning to Figure 1, the torque is transmitted from th driving mechanism 12 to the driven device by the input side 50 o the belt 10. In effect, the pulley 16 pulls on belt 10 in th direction of the arrow 52. The force in the belt between pulley 1 and 18 on the input sides^' is proportional to the amount of th stretch of the belt in the input direction 52 as shown in the curv of Figure 2. As the belt 10 is stretched, the return side 54 o the belt includes slack. The amount of slack may be controlled b design and material, the tension pulley mechanism 20 may be use which moves to apply tension onto the belt 10 to take up the slack.

When the driving and driven devices 12 and 14 are at rest, the belt 10 is generally taut without slack on the return side. Upon starting of the driving device 12, the belt 10 stretches along the input side 50 and the pulley 18 begins to turn. As this occurs, the tension uptake pulley mechanism 20, when used, moves to take up the excess slack in the belt^' 10 on the return side 54. The movement of the tension pulley mechanism 20 provides a mechanism to enable instantaneous measuring of the force applied to pulley 18 or the torque that is applied onto the driven device 14. The reading of the torque enables real time altering of the power input of the driving device 12 so that the power input of the driving device 12 is controlled by the work that is being done by the driven device 14. This also permits completely stopping the input should the force require to turn pulley 18 rise in the case of overload or failure of driven device 14.

Turning to Figure 4, another embodiment of the present invention is illustrated. The spring 10 is substantially the same as that previously described including the plurality of U-shaped members 30 with legs 32 and webs 34. Each leg 32 includes a pad member 60 which extends into the slot 36 on the spring. The pad members 60 provide for reduced deflection of the leg member 32, and additionally when the belt is in contact with pulley teeth 62 of pulley 64 like that shown in Figure 4. The pads 60 may include openings 66 to provide additional deflection of the pads. The pads 60 are generally unitarily formed on the legs during the forming process of the belt. The pads 60 generally include an arcuat surface for abutting the teeth.

Turning to Figure 5, an embodiment like that of Figure 4 i shown. In Figure 5, the spring is substantially the same as tha previously described, however, the pads 70 are upwardly arcuat members and the pulley teeth 62 no longer occupy a position unde roots 54. Also, a plate 72 is illustrated which joins two ends o the strip to form a continuous belt. The plate 72 may be welded, adhered or the like onto the ends of serpentine configurations. The plate may be in the web area, or leg area, or may extend acros the legs and be secured to the web as well as the legs.

Figure 6 is a figure like that of Figure 5 illustrating th belt like that has been previously described, however, in Figure a butt weld 80 is used to join together the ends of the belt. Th weld may be in the web area or the strip may be cut such that pair of legs are welded together. Also, the pulley may include a elasto eric cover 82 which includes a plurality of projecting teet 84. The elastomeric cover provides easy deformation whil extending the life of the belt.

Figure 7 shows the case where the belt 10 has bee encapsulated on one or both sides by an elastomer. The belt 10 ha been encapsulated by a material 92. The material 92 may have n provision for guiding or engaging a pulley as is indicated b surface 94, or may be provided with means 96 for guiding o engaging. The continuous belt of the present invention provides lower peak starting torque of the driving device, instantaneous running measurement of torque; accommodation of sudden surges of torque; and has a lower bearing load and provides energy saving from inherent lower peak design of the driving device.

While the above describes the preferred embodiment of the present invention, it will be understood that the invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.

Claims

WHAT IS CLAIMED IS:

Claim 1. An endless flexible drive belt comprising: a thin elongated strip having a pair of ends; a resilient serpentine biasing portion integrally formed i said strip between said ends; and means for permanent joining said ends with one another fo providing a continuous belt for transmitting power.

Claim 2. The continuous belt according to Claim 1 wherei said serpentine portion is continuous from end to end of sai strip.

Claim 3. The continuous belt according to Claim 1 wherei said means for joining includes a butt weld joining said ends.

Claim 4. The continuous belt according to Claim 1 wherei said means for joining includes a thin plate secured to said ends

Claim 5. The continuous belt according to Claim 1 wherei said strip is metallic.

-ID- Claim 6. A continuous belt for transmitting power comprising: a flat elongated strip having a pair of ends; a resilient serpentine biasing portion integrally formed in said strip between said ends, said resilient serpentine biasing portion comprised of a plurality of interconnected unitary U-shaped members having a pair of legs connected by a web, each alternating U-shaped member being inverted with respect to its adjacent U- shaped members, an elongated slot formed between the legs of each U-shaped member, said elongated slot extending from a lateral edge of the strip passed the longitudinal axis of the strip, said resilient serpentine biasing portion providing axial deflection along the longitudinal axis of the strip, said resilient biasing portion U-shaped members each having an overall rectangular cross section with a substantially constant thickness; and means for joining said ends with one another for providing a continuous belt for transmitting power.

Claim 7. The continuous belt according to Claim 6 wherein said serpentine portion is continuous from end to end of said strip.

Claim 8. The continuous belt according to claim 6 wherein a pad for engaging pulley teeth extends from each of said legs into said slot opposing one another. Claim 9. The continuous belt according to claim 8 wherein said pads include an open area for providing deflection of said pads.

Claim 10. The continuous belt according to claim 6 wherein said web portions having a width greater than said leg portions.

Claim 11. The continuous belt according to claim 6 wherei said strip is metallic.

Claim 12. The continuous belt according to claim 6 wherei said strip has a sufficiently large modulus of elasticity o stiffness.

Claim 13. The continuous belt according the claim 6 wherei said resilient biasing portion resiliently deflecting in a firs direction along said longitudinal axis in response to force applie on said strip and resiliently deflecting in a second directio along the thickness of the cross section in response to continue force applied on said strip.

Claim 14. The continuous belt according to claim 6 wherei said means for joining includes a butt weld joining said ends.

Claim 15. The continuous belt according to claim 6 wherei said means for joining includes a thin plate secured to said ends