Abstract:
The present disclosure relates to a flexible link drive apparatus. The flexible link drive apparatus comprises a housing that supports an input shaft and an output shaft. An eccentric is located on the input shaft, and a clutch is located on the output shaft. The present disclosure further comprises an adjustable flexible member that has a fixed end coupled to the housing through an adjustable flexible member wherein the eccentric on the input shaft deflects the adjustable flexible member to alter a degree of rotation of the clutch located on the output shaft. The present disclosure additionally relates to a method of providing variable speed power transmission by a flexible link drive apparatus. The method comprises the steps of providing a housing that supports an input shaft and an output shaft. Further, the method comprises the steps of deflecting an adjustable flexible member by an eccentric located on the input shaft which alters a degree of rotation of a clutch located on the output shaft.

Description:
This application is a continuation of Ser. No. 09/271,798 filed Mar. 18, 1999, now U.S. Pat. No. 6,122,982. 
    
    
     TECHNICAL FIELD 
     This invention generally relates to an apparatus for mechanically adjusting the output speed of a flexible link variable stroke drive. More particularly, this invention relates to a flexible link variable stroke drive that has an adjustable range of output speeds from a constant input speed. 
     BACKGROUND 
     Variable stroke drives are used on a wide variety of machinery. A variable stroke drive may be used as a primary or secondary drive apparatus on various applications, for example, in the agricultural, metalworking, packaging, paper converting, sewing, and material handling industries. 
     In the textile industry, loom manufacturers use variable stroke drives as let-off mechanisms. The variable stroke drive controls the speed at which warp yarns are released. Further, the variable stroke drive maintains constant tension on the yams and, in effect, eliminates the need for a separate motor on the loom. Another example of an application for the variable stroke drive is in the food processing industry. A variable stroke drive may be used on a food press machine. The variable stroke drive controls the speed of a conveyor that proportions, forms, and stacks food products on a conveyor assembly. A further example of an application for a variable stroke drive is in the printing industry. Variable stroke drives may be used to control a high speed sheeter that controls the speed of stacking finished sheets after printing, and a separate variable stroke drive controls the cut-to-length of the paper sheets. Another example of an application for a variable stroke drive is on a grain dryer. The variable stroke drive controls the auger speed that circulates grain for proper, uniform drying. 
     There are numerous patents that disclose the concept of a variable speed power transmission apparatus. Two examples of variable stroke drives are shown in U.S. Pat. No. 2,950,623 (the &#39;623 patent), issued to J. A. Weber, et al., and U.S. Pat. No. 3,340,743 (the &#39;743 patent) issued to S. O. Stageberg. 
     The &#39;623 patent discloses a drive mechanism having an input shaft that carries a crank arm. A first end of a chain is attached to the crank arm. Additionally, a first end of a spring is attached to the crank arm. The chain passes around a gear that is attached to an output shaft through a one-way clutch that includes a ratchet wheel and a pawl. The second end of the chain is attached to a second end of a spring. The spring wraps around a groove of a pulley member. The driving of the input shaft is intermittent and the amount of rotating may be controlled by the position of attachment on the crank arm to make longer or shorter the effective length of the crank arm in its operation of the driving mechanism of the invention. This invention discloses a variable eccentric that does not allow for greater output speed and output torque capabilities. Further, the patent discloses a constant driving mechanism with no new speed capacity. In addition, the &#39;623 system is not capable of being adjusted while the input shaft is rotating, and it is an incremental indexing drive system and not a variable speed drive. Moreover, the &#39;623 system does not provide a greater ratio of input to output speed to the extent that an overdrive is obtained. 
     The &#39;743 patent discloses a variable speed power transmission. In this device, there are several belts or links. A single eccentric is mounted on an input shaft. The output shaft is connected to an overriding clutch. The device includes an arm that is usable to vary the amount of contact between the eccentric and belt or belts. A single eccentric comes into integral contact with a belt that urges a clutch disk to a first position to move an output shaft. A spring is connected directly to a clutch disk to return the clutch disk to an original position. The spring assembly is directly connected to the clutch disk. This arrangement creates a diminished angle of travel for the clutch disk, and in accord, this produces a lesser output shaft rotation. The &#39;743 patent discloses a single eccentric with a 90° phase angle differential between eccentrics. The single eccentric utilized transmits a relatively low speed to the output shaft. Further, the system of the &#39;743 patent does not utilize a free-floating spring assembly in order to provide greater speed range for industrial applications. Moreover, the &#39;743 system does not provide a greater ratio of input to output speed to the extent that an overdrive is obtained. 
     Therefore, a need exists for an improved apparatus that is capable of having a greater input to output ratio of rotation. A need exists for an improved apparatus that offers the capability of obtaining zero speed while the apparatus is operational. A related need is an apparatus that can be adjusted while the apparatus is operational or idle. A related need exists for a fixed length eccentric that utilizes a dual-eccentric transmission unit. Further, there is a need for a dual-eccentric transmission unit that has a 45° phase angle differential between eccentric units. Last, there is a need for a free-floating spring assembly in order to provide greater speed ratio for industrial applications. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention comprises a flexible link drive apparatus. The flexible link drive apparatus comprises a housing that supports an input shaft and an output shaft. An eccentric is located on the input shaft, and a clutch is located on the output shaft. The flexible link drive apparatus further comprises an adjustable flexible member, wherein the eccentric on the input shaft deflects the adjustable flexible member to alter a degree of rotation of the clutch located on the output shaft. 
     In a further embodiment of the present invention, a method of providing variable speed power transmission by a flexible link drive apparatus is provided. The method comprises the steps of providing a housing that supports an input shaft and an output shaft. Further, the method comprises the steps of deflecting an adjustable flexible member by an eccentric located on the input shaft which alters a degree of rotation of a clutch located on the output shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The organization and manner of the structure and operation of the invention, advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, wherein like reference numerals identify like elements throughout the views, in which: 
     FIG. 1 is a top view showing the housing unit of the flexible link variable stroke apparatus. 
     FIG. 2 is a perspective view of the flexible link variable stroke apparatus. 
     FIG. 3 is a top view of the flexible link variable stroke apparatus. 
     FIG. 4 is a cross-section view of the eccentrics. 
     FIG. 5 a  is side view of the speed control device in a non-contacting position relative to an adjustable flexible member. 
     FIG. 5 b  is a side view of the speed control device in a intermediate contacting position relative to an adjustable flexible member. 
     FIG. 5 c  is a side view of the speed control device in a fully contacting position relative to an adjustable flexible member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the description of the preferred embodiment, reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It should be understood that other embodiments may be utilized as structural changes may be made without departing from the scope of the present invention. 
     In general terms, the present system is directed to a flexible link variable stroke drive that has an adjustable range of output speeds. One embodiment includes a dual-eccentric roller flexible link drive with a free-floating biasing member in order to provide an enhanced input-to-output speed ratio. 
     The system disclosed has many advantages. For example, the present system is capable of high input-to-output ratios of rotation. Additionally, the present system has the capability of obtaining zero speed while the system is operational or idle. Further, the system disclosed is able to be adjusted while the invention is operational. 
     Yet another advantage of the present system is that it has a fixed length eccentric that utilizes a dual-eccentric transmission unit. In relation to the input speed of a single eccentric versus a dual-eccentric, a dual-eccentric transmission unit allows for an increased ratio of contact between the rollers and the adjustable flexible member. The increased ratio of contact between the rollers and the adjustable flexible member provides a greater output to input speed, thereby creating an overdrive transmission unit. 
     Another advantage of a preferred embodiment is that the dual-eccentric transmission unit has a 45° phase angle differential between eccentric units, thus allowing for more contacts with the adjustable flexible member and, therefore, greater output speed. Further, the present system utilizes a free-floating spring assembly in order to provide a greater angle of travel for a clutch, in order to produce a greater output shaft rotation. 
     Referring to FIG. 1, a flexible link variable stroke drive  90  is generally shown driven by a rotational power source, such as a motor or other suitable power source. The drive  90  may be adapted to be mounted to the frame of any type of machinery that utilizes a flexible link variable stroke drive  90 . 
     The exterior of the flexible link variable stroke drive  90  is generally referred to as a housing  100 . The housing in the embodiment shown has a first endplate  110 , a second endplate  112 , and an encasing plate  114 . The housing rotationally supports an input shaft  116 , an output shaft  118 , and a control shaft  120 . The armature of the motor or other rotational power source may have a key that is adapted to be coupled to the keyway of the input shaft  116 . The output shaft  118  of the drive  90  may be adapted to be coupled to a pulley, shaft or other similar device. 
     The first  100  and second endplates  112  may have an endplate channel  122  (shown schematically in FIG. 2) located about the periphery of the first  110  and second endplates  112 . The endplate channel  122  may be adapted to engage the encasing plate  114 . In the embodiment shown, the first  110  and second  112  endplates in conjunction with the encasing plate  114  are rigidly coupled by a plurality of evenly spaced threaded securing rods  124  displaced throughout the periphery of the first  110  and second  112  endplates. 
     Referring to FIGS. 2 and 3, the internal structure of the flexible link variable stroke drive is generally shown as  200 . The input shaft  116  is mounted between the first  110  and second  112  endplates. The input shaft  116  is shown supported by the input bearings  205  mounted in the first  110  and second  112  endplates. In the embodiment shown, the input shaft  116  has four eccentrics  210 ,  212 ,  214 , and  216  that are fixedly mounted by an interference fit. Each eccentric  210 ,  212 ,  214  and  216  may comprise an elongated bar  218 ,  220 ,  222  and  224 , as well as the input rollers  226 ,  228 ,  230 ,  232 ,  234 ,  236 ,  238 , and  240  that are coupled to each respective elongated bar  218 - 224 . Since each eccentric may be of similar construction, the eccentric  210  will be explained in detail for convenience. The eccentric  210  is shown having an elongated bar  218  that has a first input roller  226  that is journaled between a first end of the elongated bar  218  that supports the bearings of the first input roller  226 . Opposite the first input roller  226  is a second input roller  228  that is journaled between a second end of the elongated bar  218  that supports the bearings of the second input roller  228 . The input rollers  226  and  228  have a bearing surface for engagement with the adjustable flexible member  276 . 
     In the embodiment shown in FIG. 4, each eccentric  210 - 216  are fixedly connected by an internal rod  242  through the center of each eccentric. The eccentrics  210 - 216  are configured in a 45° phase angle differential. Thus, the input rollers  226 - 240  connect the adjustable flexible members  276 ,  278 ,  280 , and  282  at 45° phase angle differentials. The eccentric may be indexed through an indexing hole pattern on each eccentric. The indexing hole pattern shown for each has four slots  244 ,  246 ,  248 , and  250 . The eccentrics  210 - 216  may be configured by having the slots  246  and  248  correspondingly aligned between the eccentrics  214  and  216 , thus creating a 45° angle or index between the input rollers  236  and  240 , and the input rollers  234  and  238 . Additionally, this configuration creates a 135° angle or index between the input rollers  236  and  238 , and the input rollers  234  and  240 . A pin may be inserted through the corresponding slots  246  and  248  for a permanent configuration. The eccentrics  210  and  212  are adapted to be configured similar to the eccentrics  214  and  216 . Therefore, upon the configuration of the eccentrics  210 - 216 , there is a 45° phase angle differential present in the system between the input rollers  226 - 240 . Two pins may be threaded onto the internal rod  242  for a permanent 45° angle configuration of the eccentrics  210 - 216 . 
     Referring back to FIGS. 2 and 3, the output shaft  118  is mounted between the first  110  and second  112  endplates. The output shaft  118  may be supported by output bearings  252  mounted in the first  110  and second  112  endplates. The output shaft  118  has four clutches  254 ,  256 ,  258 , and  260  that are fixedly mounted. The clutches  254 - 260  utilize a sprocket construction for the transmission of rotational speed from the input shaft  116  to the output shaft  118 . In the preferred embodiment, the clutches  254 - 260  arc one-way clutches. The one-way sprocket clutch assembly is well known to one skilled in the art, and any other suitable clutch could be utilized with the present invention. 
     The clutches  254 - 260  may be configured in conjunction to oscillate and drive the output shaft  118  in alternate oscillation movements from a zero to an infinitely adjustable output speed. The clutches  254 - 260  may be biased by the biasing members  262 ,  264 ,  266 , and  268  or tension springs. The ends of the biasing members  262 - 268  may be attached to a biasing member anchor  274 . The biasing member anchor  274  may be supported and integrally disposed between the first  110  and second  112  endplates. 
     Biasing members  262 - 268  may be mounted on the biasing member anchor  274  in a free-floating manner for the production of a greater stroke and ultimately a higher output speed. Opposite ends of the biasing members  262 - 268  are attached to adjustable flexible members  276 - 282 , respectively. The clutches  254 - 260  may be rotated in a driving stroke by the adjustable flexible members  276 - 282 . The opposite end of the adjustable flexible members  276 - 282  are connected to the adjustable flexible member anchors  284 ,  286 ,  288 , and  290 . 
     The flexible link variable stroke drive further includes a speed control device  292 . The speed control device  292  includes a cross shaft  294 , control yoke  296 , and a control shaft  120 . Further, the control device  292  may be adapted to be coupled to a rotation lever or other similar device for rotatably or linearly actuating the speed control device  292 . The control shaft  120  may be operatively connected to the C-shaped control yoke  296 . The control yoke  296  may be fixedly coupled to the cross shaft  294 . The cross shaft  294  is disposed within the control yoke  296 . The series of four flexible connection anchors  284 ,  286 ,  288 , and  290  are pivotally coupled to the cross shaft  294 . A spacer on the cross shaft  294  allows the adjustable flexible members  276 - 282  to be evenly displaced on the control shaft  120 . The speed control device  292  may be configured in the specified manner in order to control the engagement of the adjustable flexible members to the eccentric input rollers. 
     Referring to FIGS. 5 a,    5   b,  and  5   c,  the speed control device  292  is shown in various positions corresponding to a plurality of output speeds. In FIG. 5 a,  the speed control device  292  is shown at a position of corresponding zero output speed. In FIG. 5 b,  the speed control device  292  is shown at a position of corresponding intermediate output speed. In FIG. 5 c,  the speed control device  292  is shown at a position of maximum output speed. 
     By way of the control shaft  120 , the control yoke  296  may be pivotable in relation to having the adjustable flexible members  276 - 282  come into more or less contact with the input rollers,  226 - 240 , respectively. The movement of the control yoke  296 , effectuates either no deflection (as seen in FIG. 5 a ) or maximum deflection (as seen in FIG. 5 c ) of the adjustable flexible members  276 - 282  by the input rollers  226 - 240 . Additionally, the movement of the control yoke  296 , effectuates a corresponding change in speed and length of stroke of the clutches  254 - 260 . 
     Utilizing the inside face of the second endplate  112  as a point of reference, when the control yoke  296  is pivoted in the counterclockwise direction, it may move the cross shaft  294  in a direction that effectuates increased contact between the adjustable flexible members  276 - 282  and the input rollers  226 - 240 . Further, utilizing the inside face of the second endplate  112  as a point of reference, when the control yoke  296  is pivoted in the clockwise direction, it may move the cross shaft  294  in a direction that effectuates decreased contact between the adjustable flexible members  276 - 282  and the input rollers  226 - 240 . 
     Subsequently, because the motion of each eccentric may be similar, the motion of the eccentric  210  in conjunction with corresponding assemblies will be explained in detail. Referring to the eccentric  210 , as the input shaft  116  rotates, the input rollers  226  and  228  displace the adjustable flexible member  276 . The displacement of the adjustable flexible member  276  causes the clutch  254  to oscillate in a first direction and apply a tension force to the biasing member  262 , thereby initiating movement of the biasing member  262  from its natural state. Further, the displacement of the adjustable flexible member  276  drives the clutch  254  as it initiates movement of the output shaft  118  in a rotational direction. 
     As the input shaft  116  continues to rotate, there may be a gradual decrease in engagement of the input rollers  226  and  228  with the adjustable flexible member  276 . Specifically referring to the engagement of the input roller  226  with the adjustable flexible member  276 , at the period in time when the input roller  226  ceases contact with the adjustable flexible member  276 , the biasing member  262  returns the clutch  276  on the output shaft  118  back to its original position. Moreover, when the adjustable flexible member  276  leaves contact with the input roller  226 , the adjacent adjustable flexible member  278  continues the identical motion of rotational and transitional motion. This process continues eight times per revolution giving a smooth continuous rotation of the output shaft. 
     The foregoing description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The description was selected to explain the principles of the invention and their practical application to enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention not be limited by the specification, but be defined by the claims set forth below.