Abstract:
A flywheel for racing vehicles which has an increased life. The flywheel has reduced weight but resists deflection at high rpm to avoid plastic deformation and fatigue. The flywheel is formed to have more material lying in planes perpendicular to the axis of rotation while maintaining dimensions demanded by racing criteria.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to flywheels for vehicle engines and more particular to such a flywheel for a stock racing vehicle.  
           [0002]    In a ordinary passenger vehicle such as a family sedan, the inertia of the flywheel on the crankshaft coming from the internal combustion engine smooths out the rotation of the crankshaft and stores energy for use in accelerating the car after stops. The mass of the flywheel is selected for optimizing energy storage for the size and power of the engine. In the family sedan, the engine (and flywheel) rarely operates at high rpm for any extended period of time. A passenger vehicle traveling at 80 miles per hour would run at no more than about 2,500 rpm. Moreover, the mass of the flywheel makes it very robust so that failure is not a problem.  
           [0003]    In stock car racing, the rules require that the cars have flywheels, just as ordinary or “stock” vehicles. Moreover, it is required that the flywheel have the normal axial offset between the center of the flywheel and the ring gear in accordance with the common arrangement of these parts in the consumer vehicle. As a result, the flywheel does not lie entirely within a single plane. The flywheel is of considerably less importance in racing vehicles than in standard consumer vehicles because racing vehicles do not start and stop, but travel for very extended period of time at high speed. For example, a stock car may operate at 8,000-9,000 rpm for several hours to complete a race. The inertia of the flywheel becomes a hindrance because of the energy from the engine taken up to maintain rotation of the flywheel detracts from the speed of the car. Accordingly, efforts have been made to reduce the mass of the flywheel to reduce its inertia. However, reduction in the mass and the high operating speeds has led to problems with maintaining the integrity of the flywheels. The non-planar configuration of the flywheel in combination with the sustained high rpm results in considerable deflection during the course of a race. The deflection can cause plastic deformation of the flywheel and, because of speed changes, fatigue. Usually the flywheel in a stock car must be replaced after each race because it is bent or otherwise damaged.  
         SUMMARY OF THE INVENTION  
         [0004]    Among the several objects and features of the present invention may be noted the provision of a racing flywheel which is lightweight; the provision of such a flywheel that can be used for multiple races; the provision of such a flywheel which resists deflection and high rpm; and the provision of such a flywheel which is durable.  
           [0005]    Generally, a racing flywheel for a racing vehicle of the present invention has reduced deflection at high revolution for increasing durability and life. The flywheel is generally circular in shape and has gear teeth formed on its exterior. The flywheel further comprises a inner portion adapted for mounting the flywheel on a crankshaft of the vehicle, an intermediate portion extending radially outward from the inner portion, and an outer portion extending radially outward from the intermediate portion. Gear teeth disposed at the radially outer periphery of the outer portion. The inner portion lies substantially in a first plane, and the outer portion lies substantially in a second plane located to one side of the first plane and substantially parallel to the first plane whereby the flywheel resists deflection at high revolution.  
           [0006]    Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is an elevation of a flywheel incorporated on a crankshaft in conjunction with a clutch assembly;  
         [0008]    [0008]FIG. 2 is a top plan view of the flywheel;  
         [0009]    [0009]FIG. 3 is a bottom plan view of the flywheel;  
         [0010]    [0010]FIG. 4 is a fragmentary section taken in the plane including line  4 - 4  of FIG. 3; and  
         [0011]    [0011]FIG. 5 is a section like FIG. 4, but showing a prior art configuration. 
     
    
       [0012]    Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring now to the drawings and in particular FIGS.  1 - 3 , a flywheel of the present invention (generally indicated at  10 ) is mounted on a crankshaft CR extending from an internal combustion engine (not shown) for conjoint rotation with the crankshaft. In the preferred embodiment, the flywheel  10  is incorporated into a racing vehicle (not shown), such as a stock car. The crankshaft CR is received in a central opening  12  of the flywheel  10 . The attachment may be conventional, and is made by bolts B extending through openings in a flange F fixedly joined to the crankshaft CR and through holes  14  in an inner portion (generally indicated at  16 ) of the flywheel  10 . A clutch assembly CA includes a cover plate CP mounted on the flywheel  10  for selectively interconnecting the flywheel and crankshaft CR with an input shaft IS for powering the racing vehicle. A disc D attached to the input shaft IS for conjoint rotation is engageable with the flywheel  10  and a pressure plate P of the clutch assembly CA for interconnecting the input shaft and flywheel. The clutch assembly CA can be a conventional racing clutch assembly, such as the clutch assembly disclosed in co-assigned U.S. Pat. No. 5,785,163, the disclosure of which is incorporated by reference. Accordingly, no further description of the clutch assembly will be made.  
         [0014]    The flywheel  10  is generally circular in shape and is made of conventional material such as 4140 steel. The flywheel  10  has several generally annular portions including the inner portion  16  which includes the holes  14  for the bolts B which mount the flywheel on the crankshaft CR. An intermediate portion  18  extends radially outwardly from the inner portion  16 , and an outer portion  20  extends radially outwardly from the intermediate portion to the periphery of the flywheel  10  were a ring gear  22  is located. The ring gear has teeth  24  disposed to mesh with the starter (not shown) for turning the flywheel  10  and crankshaft CR to start the engine. In a personal car and in a counterpart stock racing vehicle the axial location of the ring gear (relative to the axis of the crankshaft CR) is offset on the order of about 150 thousandths of an inch. This amount varies from vehicle to vehicle, but 0.150 inches is the amount of offset of the ring gear  22  from the inner portion  16  of the flywheel described herein. Referring to FIG. 4, the outer portion  20  lies in a second plane P 2  axially located to one side of a first plane P 1  of the inner portion  16 . The ring gear  22  also lies in the second plane. Both the first and second planes P 1 , P 2  are generally perpendicular to an axis of rotation AX of the crankshaft CR.  
         [0015]    The intermediate portion  18  of the flywheel  10  extends axially to one side of a first plane P 1  of the inner portion  16 . A radially inner section  30  of the intermediate portion  18  extends axially (at an angle of about 150° to the first plane P 1  of the inner portion  16 ) to a center section  32 . The center section lies substantially in a third plane P 3  perpendicular to the axis AX of the crankshaft CR and located on the opposite side of the first plane P 1  of the inner portion  16  from the second plane P 2  of the outer portion  20 . The center section  32  of the intermediate portion  18  includes a flat annular frictional material platform  34  spaced farthest axially from the inner portion  16  and disposed for engaging (through a heat shield) the discs D of the clutch assembly CA for interconnection of the flywheel  10  with the input shaft IS. On a radius just outside the outer edge of the platform  34  are located apertures  36  for mounting the clutch cover plate CP on the flywheel  10  (FIG. 2). On the same radius, arcuate recesses  38  are formed in the flywheel  10  to further reduce the weight of the flywheel. The recesses  38  are about 0.05 inches deep in the illustrated embodiment. However, it is to be understood that the recesses  38  could be eliminated without departing from the scope of the present invention. Weight is also saved by making the outer portion  20  thinner than conventional. Again in the illustrated embodiment, the thickness of the outer portion is about 0.125 inches, whereas the prior flywheels (e.g., as shown in FIG. 5) are about 0.160 inches thick. A radially outer section  40  of the intermediate portion  18  includes a first turn  40 A from the third plane P 3  of the center section  32  toward the first plane P 1  of the inner portion  16 . The outer section  40  passes through the first plane P 1  of the inner portion  16  and has a second turn  40 B into the second plane P 2  of the outer portion  20 .  
         [0016]    In the illustrated embodiment, the radius R 1  of the flywheel  10  (measured from the center to the inside of the ring gear  22 ) is about 6.098 inches. The radial width W 1  of the inner portion  16  is about 1.135 inches, the width W 2  of the intermediate portion  18  is about 2.802 inches and the width W 3  of the outer portion  20  is about 0.921 inches. Thus, in a preferred embodiment, the planar outer portion  20  of the flywheel  10  occupies about 15% of the total radius of the flywheel, or 19% of the total radial dimension of the flywheel material (i.e., the radius of the flywheel less the radius of the central opening  12 ). Together, the planar inner and outer portions  16 ,  20  occupy 34% of the total radius of the flywheel  10  or 42% of the total radial dimension of the flywheel material. The center section  32  of the intermediate portion  18  is also substantially planar and has a width W 4  of about 1.948 inches. If this planar extent is included, the total percentage of the flywheel  10  lying in planes perpendicular to the axis AX of the crankshaft CR is about 66% of the total radius of the flywheel  10  or about 82% of the total radial dimension of the flywheel material Stated another way, only about 18% of the total radius of the flywheel material likes outside of a plane perpendicular to the axis AX of the crankshaft CR. Preferably at least about 60% of the surface area of the flywheel material lies in planes perpendicular to the axis AX of the crankshaft CR, more preferably about 75% and most preferably at least about 80%. The absolute dimensions given are exemplary only and may be other than described without departing from the scope of the present invention.  
         [0017]    Referring to FIG. 5, a prior art flywheel  110  is shown to have an inner portion  116 , an intermediate portion  118 , an outer portion  120  and a ring gear  122 . The configuration of the inner portion  116  is substantially the same as the configuration of the inner portion  16  of the flywheel  10  of the present invention. The intermediate portion  118  is somewhat similar to the configuration of the intermediate portion  18  of the flywheel  10 . However, the intermediate portion  118  does not have arcuate recesses (not show) like the arcuate recesses  38  of the flywheel  10  because the strength cannot be sacrificed in the prior art flywheel  110 . Most importantly, radially outer section  140  of the intermediate portion  118  is not formed with first and second turns like the outer section  40  of the present invention. The outer portion  120  of the prior art flywheel  110  likes in a plane P 2 ′ which is skew to both the plane P 1 ′ of the inner portion and the plane P 3 ′ of the intermediate portion, as well as to the axis AX′ of the crankshaft. No part of the outer portion  120  extends in a plane perpendicular to the axis AX′ of the crankshaft. This configuration of the outer portion  120  leads to substantial axial deflection D pr  of the flywheel  110 . Deflection is measured as the movement of the outer edge of the flywheel in a direction parallel to the axis AX of the crankshaft CR from the position of the outer edge when the flywheel is at rest. It has been found that at 8,000 rpm the conventional flywheel  110  deflects to about 0.250 inches, an amount which usually results in bending the flywheel so that it is no longer capable of use. In contrast with the present invention, the deflection D new  of the outer edge of the flywheel  10  at 8,000 rpm is about 0.030 to 0.040 inches. At this level of deflection, it is believed that the flywheel  10  will retain its integrity for long periods of time. It will not be necessary to replace the flywheel  10  after every race, reducing the cost of operating the racing vehicle. Moreover, the flywheel  10  is lighter in weight while having a greater resistance to deflection for superior performance.  
         [0018]    When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
         [0019]    In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.  
         [0020]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.