AU669663B2 - Endless flexible drive belt - Google Patents

Description

Or~ DAIL 13/12/93 APPLN. 10 21415/92 IIli 111DII AOJP DATE 24/02/94 PCT NUMBER PCT/US92/04123 11111111111I111111111111111111111111111 AU9221415 INTERNATIONAL APPLICATION PUBLISHED) UND)ER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification (11) International Publication Nurnber; WO 93/23688 F16G 1/00 IAl1 (43) International Publication Date: 25 November 1993 (25.11.93) (21) International Application Number: (22) International Filing Date: PCTUS9204l231 18 May I92(80.2 (81) Designated States: AU', CA, JP, US, European patent (AT, BE, CH-, DEi, DK, ES, FR, GB. GR, IT, LU, MIC, NL, S E).

Published Mit international searchi report.

(71) Applicant (for all des~qnated States except US): PRO PRIE- TARY TECHNOLOGY, INC. [US/US]; 25240 Lahser Road, Southfield, Nil 48034 (US).

Inventor; and Inventor/Applicant (for U'S only): BARTHOLOMEW, Donald, Dekle [US/US]; 35442 Jefferson, 400 On the Lake, Unit 32C, Nit. Clemens, Nil 48045 (US).

(74) Agents: MILLER, Keith et al.; Harness, Dickey& Pierce, P.O. Box 828, Bloomfield Hills, Nil 48303 (US).

(54)Title: ENDLESS FLEXIBLE DRIVE BELT 62 32 400 (57) 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 betwveen the ends. Also, the ends are permanently joined with one another to provide an endless belt to transit power or torque.

QAO\liR\oPaa1415.C -29/96 2 ENDLESS FLEXIBLE DRIVE BELT BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to drive belts and, more particularly, to an endless or continuous drive belt with a serpentine spring biasing portion.

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

In the automotive industry, fan belts are commonly used to transmit power from an engine to various accessories such as 15 compressors, alternators or the like. During start-up of the engine, a peak torque is required to begin to turn or rotate the 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 a degree that may permanently deform the belt. Ordinarily, an adjustable tensioner is utilized to take up the excessive play in the fan belt. Thus, it would be desirable to provide a continuous belt which would reduce the peak torque required by the engine without permanent deformation of the belt.

Accordingly, it is an object of the present invention to overcome the above disadvantages.

According to the present invention there is provided an endless flexible drive belt comprising: a thin, generally planar elongated strip having a pair S3: f ends; I" i QOM\W G1ui 4I5.C 291496 2A 5a

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a resilient serpentine biasing portion integrally formed in said generally planar strip between said ends, the serpentine biasing portion providing for longitudinal deflection of the belt; and means -or permanent joining said ends with one another for providing a continuous belt for transmitting power.

The invention also provides 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 15 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 past a central 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.

The present invention provides a continuous belt which can have 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 30 peak torque at start-up.

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QOP\oI'R\Gc I45.C 29/496 2B 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 "I belt in accordance with the present invention.

15 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 o accordance with the present invention.

S 2 S A C WO 93/23688 PCT/US92/04123 -3- Figure 6 is a cross section view of another embodiment of the present invention.

Figure 7 is a cross section view of another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning to the Figures, particularly Figure 1, a continuous belt is shown and designated with the reference numeral 10. The continuous belt 10 is illustrated with a mechanism for driving the 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 the driving and driven devices via pulleys 16 and 18. Also, a belt tensioning device 20 is positioned on the return side of the belt to take up slack in the belt The belt 10 is an elongated strip and may be formed from any suitable metallic sheet material having requisite strength resilient characteristics. The belt 10 has a serpentine pattern 22 continuous throughout the belt 10 from one end to the other. The serpentine pattern 22 includes a plurality of interconnected unitary U-shaped members 30 having a pair of legs 32 connected by a web 34. Each alternating U-shaped member 30 is inverted with respect to its adjacent U-shaped members 30. The U-shaped members have an overall rectangular cross section with a substantially constant thickness. A slot 36 which separates legs 32 extends from a lateral edge of the belt inward to the web 34, a distance beyond the longitudinal axis of the belt 10. The serpentine U-shaped configuration is like that disclosed in applicant's U.S. Patent No.

WO 93/23688 PCT/US92/04123 -4- 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 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 Fl-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 WO 93/23688 IICT/US92/0123 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 point designated with reference letter illustrates the normal running force that is generally applied to the belt when the driving mechanism is continuously operating. The point designates the peak force required at start-up to begin movement of the belt, and devices driven by the belt. As can be seen in the graph, the peak force in the present invention is much less than that of currently used belts. Also, while the displacement or elongation of the present invention is more than that of currently used belts, the peak force is significantly reduced. The belt tends to individually start individual driven devices when more than one device 14 is being driven, and the elongation of the belt is controlled by the design and material of the belt Returning to Figure 1, the torque is transmitted from the driving mechanism 12 to the driven device by the input side 50 of the belt 10. In effect, the pulley 16 pulls on belt 10 in the direction of the arrow 52. The force in the belt between pulley 16 and 18 on the input sides' is proportional to the amount of the stretch of the belt in the input direction 52 as shown in the curve of Figure 2. As the belt 10 is stretched, the return side 54 of the belt includes slack. The amount of slack may be controlled by design and material, the tension pulley mechanism 20 may be used WO 93/23688 PCI'/US92/04123 -6which 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 are generally unitarily formed on the legs during the forming WO 93/23688 PCT/US92/04123 -7process of the belt. The pads 60 generally include an arcuate surface for abutting the teeth.

Turning to Figure 5, an embodiment like that of Figure 4 is shown. In Figure 5, the spring is substantially the same as that previously described, however, the pads 70 are upwardly arcuate members and the pulley teeth 62 no longer occupy a position under roots 54. Also, a plate 72 is illustrated which joins two ends of 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 across the legs and be secured to the web as well as the legs.

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

Figure 7 shows the case where the belt 10 has been encapsulated on one or both sides by an elastomer. The belt 10 has been encapsulated by a material 92. The material 92 may have no provision for guiding or engaging a pulley as is indicated by surface 94, or may be provided with means 96 for guiding or engaging.

WO 93/23688 PCT/US92/04123 -8- 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 (16)

1. An endless flexible drive belt comprising: a thin, generally planar elongated strip having a pair of ends; a resilient serpentine biasing portion integrally formed in said generally planar strip between said ends, the serpentine biasing portion providing for longitudinal deflection of the belt; and means for permanent joining said ends with one another for providing a continuous belt for transmitting power.

2. The continuous belt according to claim 1 wherein said serpentine portion is continuous from end to end of said strip. •o

3. The continuous belt according to claim 1 wherein said means for joining includes a butt weld joining said ends. 9 9

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

The continuous belt according to claim 1 wherein said strip is metallic.

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- ii3 0 shaped members having a pair of legs connected by a web, each *;V7 o^ Q:\OP1R\GC'24S.C 29/4796 10 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 past a central 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. S

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

8. The continuous belt according to claim 6 wherein a pad for engaging pulley teeth extends from each of said legs into said SQ slot opposing one another. S 20

9. The continuous belt according to claim 8 wherein said pads include an open area for providing deflection of said pads.

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

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

12. The continuous belt according to claim 6 wherein said strip has a sufficiently large modulus of elasticity or stiffness. .,i O:\OPIR\GCF\2141S.C 29/46 11

13. The continuous belt according to claim 6 wherein said resilient biasing portion resiliently deflecting in a first direction along said longitudinal axis in response to force applied on said strip and resiliently deflecting in a second direction along the thickness of the cross section in response to continued force applied on said strip.

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

The continuous belt according to claim 6 wherein said means for joining includes a thin plate secured to said ends. 4

16. An endless flexible drive belt substantially as 15 hereinbefore described with reference to the accompanying drawings. DATED this 29th day of April, 1996 PROPRIETARY TECHNOLOGY, INC. By its Patent Attorneys DAVIES COLLISON CAVE