Abstract:
The invention comprises a tensioning idler. An outer belt bearing ring is resiliently engaged to an inner ring. The belt bearing ring and inner ring each rotate about an axis of rotation. The belt bearing ring is connected to the inner ring with the resilient material whereby the belt bearing ring rotates about an axis of rotation that is eccentrically moveable in a plane with respect to an inner ring axis of rotation. The resilient material imparts a belt tension as the belt bearing ring rotates. The resilient material may comprise springs, compressible fluids, incompressible fluids, or elastomers or a combination of the foregoing. The tensioner is mounted on an engine, bracket, or other device.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to a tensioning idler, and more particularly, to a tensioning idler having a belt bearing surface with an axis of rotation that is moveable in a plane with respect to an inner ring axis of rotation.  
         BACKGROUND OF THE INVENTION  
         [0002]    In prior art belt drive systems, tensioning the belt is necessary to effectively transfer power from a driver to a driven pulley. Mechanical tensioners with springs or hydraulic cylinders are known devices used in various designs. Each of these tensioners applies a tensioning force to a belt via an idler pulley on an arm. The tensioning mechanism (spring, hydraulic cylinder, etc.) is generally located outside the idler and the force is transferred through the arm to the idler.  
           [0003]    Representative of the art is U.S. Pat. No. 4,571,222 (1986) to Brandenstein et al. which discloses a tension roller with a supporting member, pivoted on a pivot stud against the force of a tension spring, and rotatably supported in a roller sleeve by a bearing.  
           [0004]    The prior art tensioners rely upon an arrangement wherein the eccentric portion is contained within a bearing radius. This limits the movement and adjustability of the prior art tensioner to that of a predetermined radius for the moveable eccentric portion. If the predetermined radius is exceeded by belt stretch for example, the tensioner looses effectiveness. This is generally the case as a belt wears. Further, the prior art eccentric tensioners are relatively complex and require additional machining to produce the components with the proper form and fit.  
           [0005]    What is needed is a tensioning idler having an outer belt bearing ring with an axis of rotation that is moveable in a plane. What is needed is a tensioning idler having an outer belt bearing ring with an axis of rotation that is moveable in a plane with respect to an inner ring axis of rotation. What is needed is a tensioning idler having an eccentric movement disposed outside of a bearing. The present invention meets these needs.  
         SUMMARY OF THE INVENTION  
         [0006]    The primary aspect of the invention is to provide a tensioning idler having an outer belt bearing ring with an axis of rotation that is moveable in a plane.  
           [0007]    Another aspect of the invention is to provide a tensioning idler having an outer belt bearing ring with an axis of rotation that is moveable in a plane with respect to an inner ring axis of rotation.  
           [0008]    Another aspect of the invention is to provide a tensioning idler having an eccentric movement disposed outside of a bearing.  
           [0009]    Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.  
           [0010]    The invention comprises a tensioning idler. An outer belt bearing ring is resiliently engaged to an inner ring. The belt bearing ring and inner ring each rotate about an axis of rotation. The belt bearing ring is connected to the inner ring with the resilient material whereby the belt bearing ring rotates about an axis of rotation that is eccentrically moveable in a plane with respect to an inner ring axis of rotation. The resilient material imparts a belt tension as the belt bearing ring rotates. The resilient material may comprise springs, compressible fluids, incompressible fluids, or elastomers or a combination of the foregoing. The tensioner is mounted on an engine, bracket, or other device. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a cross-sectional side view of the inventive tensioning idler.  
         [0012]    [0012]FIG. 2 is a detail of a coil spring.  
         [0013]    [0013]FIG. 3 is a cross-sectional side view of an alternate embodiment.  
         [0014]    [0014]FIG. 4 is a cross-sectional side view of an alternate embodiment.  
         [0015]    [0015]FIG. 5 is a detail of a leaf spring.  
         [0016]    [0016]FIG. 6 is a cross-sectional side view of an alternate embodiment.  
         [0017]    [0017]FIG. 7 is a detail of a chamber.  
         [0018]    [0018]FIG. 8 is a cross-sectional side view of an alternate embodiment.  
         [0019]    [0019]FIG. 9 is a detail of a rubber wheel.  
         [0020]    [0020]FIG. 10 is a cross-sectional side view of an alternate embodiment.  
         [0021]    [0021]FIG. 11 is a detail of a leaf spring.  
         [0022]    [0022]FIG. 12 is a cross-sectional side view of an alternate embodiment.  
         [0023]    [0023]FIG. 13 is a detail of a steel strip spring.  
         [0024]    [0024]FIG. 14 is a cross-sectional perspective view of the inventive tensioner under load.  
         [0025]    [0025]FIG. 15 is a cross-sectional perspective view of the inventive tensioner with no load. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    [0026]FIG. 1 is a cross-sectional side view of the inventive tensioning idler. Belt bearing ring  10  is substantially circular and has a “U” cross section. Inner ring  20  is also substantially circular and has an inverted “U” cross section with respect to the outer ring  10 . Inner ring  20  is journaled to shaft  70  by bearing  30 . Bearing  30  comprises a ball bearing, but may also comprise any anti-friction bearing suitable for the use described herein, or its equivalents. Inner ring  20  is engaged with an outer race of bearing  30 .  
         [0027]    Belt bearing ring  10  and inner ring  20  cooperate to define a chamber  40  that contains a resilient member  60 .  
         [0028]    One or more damping surfaces  50 ,  51  may be used between inner ring  20  and belt bearing ring  10 . Damping surfaces  50 ,  51  comprise a plane of sliding, frictional engagement having a coefficient of friction disposed between belt bearing ring  10  and a member  12 , and belt bearing ring  10  and inner ring  20 . Damping surfaces  50 ,  51  act to damp a movement of belt bearing ring  10  relative to inner ring  20  during operation. Damping rings  50 ,  51  also act as a seal to keep contaminants from entering the chamber  40 .  
         [0029]    Belt bearing ring  10  and inner ring  20  may comprise any suitable material, including steel, aluminum, magnesium, thermoset plastic or thermoplastic material, or any combination or equivalent thereof. Inner ring  20  and belt bearing ring  10  may also comprise any lightweight material, including nylon, or equivalents, to reduce centrifugal forces created during operation. In the preferred embodiment, inner ring  20  and outer ring  10  each comprise Nylon 6.6 with PTFE, and may or may not comprise a damping material having a coefficient of friction for surfaces  50 ,  51 .  
         [0030]    Damping surfaces  50 ,  51  in the preferred embodiment comprise PTFE. A diameter and thickness of both the inner ring and outer ring can be any size as required by the design. A diameter of belt bearing ring  10  can be selected to create any operational amplitude as may be needed by a system, see FIG. 14.  
         [0031]    For ease of assembly, belt bearing ring  10  may comprise two parts, an “L” section  11 , and member  12  to be put on an open side of the “L” section  11  when fully assembled. Member  12  is attached to L section  11  after assembly of resilient member  60  in chamber  40 .  
         [0032]    Resilient member  60  comprises a member having a spring rate, depending on the damping, amplitude, or belt tension (load) required by the system. The spring in FIG. 1 is a coil spring  61 . Two or more coil springs may be used in chamber  40 , each of which extends radially between inner ring  20  and outer ring  10 . The number of springs  61  is determined by the particular system requirements.  
         [0033]    Post  70  is used to attach the inventive idler to a mounting surface (not shown), such as the surface of an engine. Post  70  may comprise a threaded connector or press-fit stud, or equivalents thereof. Dust cover  80  prevents dirt and debris from entering bearing  30 .  
         [0034]    In operation, an axis of rotation A-A of outer ring  10  is moveable in a plane that is normal to the axis of rotation, see FIG. 14. An axis of rotation B-B of inner ring  20  is substantially parallel to the axis of rotation of outer ring  10 . More particularly, an axis of rotation is substantially parallel to axis A-A and normal to a plane P/P. In this way an eccentric movement of belt bearing ring  10  is disposed outside of bearing  30 . That is, bearing  30  does not move eccentrically with respect to a mounting post  70  as in the prior art, instead ring  10  moves eccentrically about the inner ring  20  and thereby eccentrically about a bearing  30 .  
         [0035]    [0035]FIG. 2 is a detail of a coil spring. Coil spring  60  has a predetermined spring rate as required by an operating condition.  
         [0036]    [0036]FIG. 3 is a cross-sectional side view of an alternate embodiment. The parts shown in FIG. 3 are as described for FIG. 1 with the exception that resilient member  60  comprises elastic balls  62 . Small spherical elastomer balls fill chamber  40  to the extent allowed by their spherical shape. The air space between balls  62  allows movement and deformation of the balls under load. This, in turn, allows a controlled planar movement of belt bearing ring  10  axis of rotation with respect to the inner ring  20 . It is preferred that a diameter of each ball be approximately 1/6 th  or less of a radial distance R from the inner ring  20  to ring  10  in order to facilitate a fluid-like movement or behavior of the balls  62  comprising resilient member  60  during operation.  
         [0037]    [0037]FIG. 4 is a cross-sectional side view of an alternate embodiment. The parts shown in FIG. 4 are as described for FIG. 1 with the exception that a resilient member  60  comprises a plurality of leaf springs  63 . Each leaf spring  63  extends radially from inner ring  20  to ring  10  in chamber  40 . During operation each leaf spring flexes thereby allowing a controlled planar movement of a ring  10  axis of rotation A-A with respect to the inner ring  20 .  
         [0038]    [0038]FIG. 5 is a detail of a leaf spring. Leaf spring  63  having a predetermined deflection to facilitate a movement of ring  10  during operation.  
         [0039]    [0039]FIG. 6 is a cross-sectional side view of an alternate embodiment. The parts in FIG. 6 are as described for FIG. 1 with the exception that the resilient member  60  comprises fluid chamber  64 . Chamber  64  is contained in chamber  40 . Chamber  64  may contain any fluid, including a compressible gas, or an incompressible liquid or liquids of various viscosities. Chamber  64  may also contain any moveable solid, for example in a granular form, or a combination of or equivalents of any of the foregoing. The material in chamber  64  may be displaced from side to side, compressed, or a combination of both. Chamber  64  may comprise a flexible elastomer to match the shape of chamber  40 . Chamber  64  may be permanently sealed or have a valve for pressure and volume adjustments in the case of a compressible fluid. One skilled in the art can appreciate that a pressure of a compressible fluid in chamber  64  can be adjusted to accommodate operational changes as well. A movement of a fluid contained in chamber  64  allows a controlled planar movement of a ring  10  axis of rotation A-A with respect to the inner ring  20 .  
         [0040]    [0040]FIG. 7 is a detail of a fluid chamber. Valve  64 a may be used to vary a pressure in chamber  64  in response to an operating condition.  
         [0041]    [0041]FIG. 8 is a cross-sectional side view of an alternate embodiment. The parts in FIG. 8 are as described for FIG. 1 with the exception that the resilient member  60  comprises a resilient wheel  65 . Wheel  65  may comprise an elastomeric ring. Wheel  65  may have a solid form, or comprise slots  650  to allow for compression deformation of spokes  651 . Flexing of wheel  65  allows a controlled planar movement of a ring  10  axis of rotation A-A with respect to the inner ring  20 . Elastomeric wheel  65  may comprise any natural or synthetic rubber, or any combination thereof, including equivalents.  
         [0042]    [0042]FIG. 9 is a detail of a rubber wheel. Wheel  65  comprises spokes  651  with interspersed gaps  650 .  
         [0043]    [0043]FIG. 10 is a cross-sectional side view of an alternate embodiment. The parts in FIG. 10 are as described for FIG. 1 with the exception that the resilient member  60  comprises continuous leaf spring  66 . Spring  66  comprises a continuous series of leaf spring spokes  662  which extend radially toward the inner ring  20  from an outer circumference  661  in a zigzag arrangement. Each leaf spring has a spring rate adjusted according to a particular system operating condition. Flexing of each leaf spring spoke  662  allows a controlled planar movement of a ring  10  axis of rotation A-A with respect to the inner ring  20 .  
         [0044]    [0044]FIG. 11 is a detail of a leaf spring. Spring  66  comprises spokes  662  with interspersed gaps  663 . A spring rate may be adjusted depending upon an operating requirement.  
         [0045]    [0045]FIG. 12 is a cross-sectional side view of an alternate embodiment. The parts in FIG. 12 are as described for FIG. 1 with the exception that the resilient member  60  comprises steel strip spring  67  formed in a generally spiral shape. A first end  672  is engaged with inner ring  20 . A second end  671  is engaged with outer ring  10 . Rotational and radial flexing of the steel strip spring allows a controlled planar movement of a ring  10  axis of rotation A-A with respect to the inner ring  20 .  
         [0046]    [0046]FIG. 13 is a detail of a steel strip spring. Spring  67  may comprises a number of coils C as required by an operating condition.  
         [0047]    In each embodiment, the resilient member that is on the side of the belt bearing ring that is touching the belt (contact side) is under compression. The opposite side (180 degrees from the contact side) is under tension, or is under no load.  
         [0048]    One can appreciate that the instant invention is more compact than prior art tensioners due to the compact nature of the components and the manner in which they are assembled and operate. For example, the inventive tensioner does not comprise an “arm” as used in numerous prior art tensioners. This results in a considerable space saving as compared to larger prior art tensioners.  
         [0049]    [0049]FIG. 14 is a cross-sectional perspective view of the inventive tensioner under load. As one can see, an axis of rotation A-A of belt bearing ring  10  does not coincide with an axis B-B of inner ring  20  when the inventive tensioner is subject to a belt load. The depicted configuration would result from a belt load L being applied as shown to belt bearing ring  10 . An amplitude of movement of ring  10  relative to ring  20  is dependent upon a dimension K of ring  20 .  
         [0050]    [0050]FIG. 15 is a cross-sectional perspective view of the inventive tensioner with no load. Under no load that A-A and B-B of belt bearing ring  10  and inner ring  20  are concentric. Compared to FIG. 14 one can readily see that the axis of rotation A-A of the belt bearing ring  10  is moveable in a plane extending normally to the axis of rotation A-A. Axis of rotation A-A is moveable independently of an axis of rotation B-B of the inner ring  20 .  
         [0051]    Although various forms 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 without departing from the spirit and scope of the invention described herein.