Abstract:
An apparatus for damping vibrations between the torque producing device and the transmission of torque has a member having a pair of generally parallel plates with a spacer bar disposed between the plates, and an output member disposed between the plates. The input and output members are angularly movable with each other about a common axis and relative to each other from neutral positions. A torsional damping member is disposed between the input and output members, the torsional damping members being in contact with the spacer bar and enclosed within an annular chamber formed between the input and output members.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to substantially flange like rotary components which can be utilized for the reduction of torsional stresses or vibrations in drive trains. The device contains energy storing devices composed of coil springs which serve to transmit torque between a rotary input and an output member forming part of a torsional vibration coupling for use in the powertrain between the prime mover (such as a combustion engine or other torque producing element) and the variable speed transmission and/or another driven unit. More particularly, the invention relates to improvement in the substantially flange like rotary components which are especially suitable for the transmission of torque to or from coil springs which together form an annular energy absorbing device interposed between coaxial input and output members which can rotate about a common axis. 
     It is well known to employ annular energy absorbing devices of the above outlined character. A first flange is rotatably coupled to and driven by a torque producing element when the mechanism employing such structure is engaged. A second flange is rotatably coupled to the transmission or drive train of the mechanism. The parallel first and second flanges are coupled by energy absorbing devices such as springs disposed between the flanges. The flanges are angularly movable with each other about a common axis and relative to each other about neutral positions. 
     In situations where the first and second flanges are rotating at the same speed, the spring is in a neutral position. When a torque load is applied to either the input or the output shaft, the relative angular rotation speed or velocity is changed. The plates, while still rotating, will move away from the neutral position compressing the springs and transmitting the load to the other member. The coupling acts to reduce the “shock” between the torque producing and the torque transmitting members. 
     It is known that due to the stresses seen in the vibration damping apparatus as described above, certain failure modes are observed. These failure modes include wear of the spring components, as well as a substantial amount of wear in the chambers holding these components. This wear reduces the efficiency and durability of the springs and holding chambers and lead to noise, as well as the potential of catastrophic failure of the internal components. 
     As such, the invention described herein is embodied in an apparatus for dampening vibrations in a powertrain between a torque producing and a torque transmission assembly. The improved apparatus comprises at least two components which are rotatable relative to each other about a common axis and include a first component connectable with the torque producing elements (e.g. with the crankshaft of an internal combustion engine) and a second component which is connectable with the torque transmission assembly (e.g. with the input shaft of a variable speed transmission), and means for transmitting torque between the first and second components. Included within the apparatus is a chamber and/or chambers for holding the spring elements. These chambers are located between the input element and the output element of the apparatus; more particularly, between the input element and the spacer ring of the output element. The apparatus contains with the chambers torsionally elastic dampers or springs. In some instances it may be desirable to include friction materials between the flange members to help dampen vibrations by providing hysteresis or Coulomb friction within the torsional vibration coupling. It has been found that the aforementioned configuration significantly reduces the amount of wear on the spring and flange members of the apparatus. 
     An optional ledge portion can be provided for separating a portion of the torsional damping member from the spacer ring. This allows contact between the spring and the spacer bar element where there is the minimum translation and/or relative motion of the coupling member, thus reducing wear. 
     In view of the aforementioned problems, it is an object of the current invention to provide a torsional vibration coupling which reduces the amount of wear on its components. 
     It is another object of the current invention to provide a torsional vibration coupling which has a reduction in variation of uncontrolled hysterisis. 
     It is another object of the current invention to provide a torsional vibration coupling where changes in the damping rate during the life of the product is minimized. 
     It is further an object of the current invention to provide a torsional vibration coupling which is less susceptible to corrosion and which requires less frequent lubrication of its elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to appreciate the manner in which the advantages and objects of the invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding these drawings only depict preferred embodiments of the present invention and are not, therefore, to be considered limiting in scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
     FIGS. 1 a  and  1   b  depict torsional coupling members as known in the prior art; 
     FIGS. 2 a  and  2   b  depict a torsional coupling of the present invention; 
     FIGS. 3 a - 3   d  depict another embodiment of the current invention; 
     FIGS. 4 a - 4   c  depict actuation of the current invention under loading condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 a  depicts a torsional vibration coupling as known in the prior art. Depicted is a cut-away view of a torsional vibration coupling having an output flange  10  and a pair of input flanges  15  being spaced apart by spacer  20 . Output flange  10  has a slot  38  which houses a spring  30 . Input flanges  15  have a pair of holding flanges  25 , a forward bearing surface  28 , and an aft bearing surface  29 , disposed next to slot  38  for holding spring  30 . Slot  38  has a slot forward wall  50 , a slot top wall  40 , a slot aft wall  55 , and a slot bottom wall  45 . A torsional damping member in the form of a spring  30  is compressed between the forward bearing surface  28  and slot aft wall  55  and applies force to the flanges whenever rotation velocity between the output flange  10  and the input flanges  15 . 
     Depicted in FIG. 2 a  is a side view of a cut-away section of a torsional coupling of the preferred embodiment. The torsional coupling has at least one output flange  10  and at least one pair of parallel input flanges  15  separated by a spacer ring  20 . The output flange  10  which is coupled to a hub portion  11  is annularly surrounded by the spacer  20 , having a plurality of channels  60 . The channel has a forward wall  65 , an aft wall  70 , and a bottom wall  72 . The spacer  20  has a spacer bearing surface  75  disposed adjacent the output flange  10 . A cavity is formed by channel  60  and spacer bearing surface  75 . Input flanges  15  have a plurality of holding flanges  25  disposed about the channel  60  further defining a volume  62  therein. 
     Spring  30  is disposed within the channel  60  or volume  62  for transmitting torque between the input and output members. It should be noted that the present embodiment allows for a transmission of rotational energies in the fore and aft direction. It should be further noted that whereas a single output flange  10  can be coupled to a pair of input flanges  15 , a plurality of such arrangements is also functional as depicted in FIG. 2 b . Further depicted in FIG. 2 b  the spacer bearing surface  75  is shown and a curved groove disposed thereon. Spacer bearing surface  75  functions to reduce the amount of wear on spring  30  by reducing the amount of relative movement of spring  30  with respect to channel  60 . The radius of the groove preferably is the outside diameter of spring  30 . While this is the preferred surface structure, it should be noted that other surfaces, such as flat, will also function. The curved surface reduces the contact stress between the springs and the spaces by increasing the contact surface area, thereby increasing the component&#39;s life. 
     Depicted in FIG. 3 a  is another embodiment of the current invention. Depicted is a torsion damping apparatus having an output member  10 , a pair of input members  15  being separated by the spacer ring  20 . The output member has a plurality of teeth  125  defining a plurality of channels  120  therebetween. The channel  120  has a bottom wall  105 , forward wall  110  and aft wall  115 . The teeth  125  define a recess portion  90  and ledge portion  80 . The ledge portion  80 , which has a ledge bearing surface  85  in contact with forward wall  110  and ledge face  82 , partially encloses channel  120 . As with the previous embodiment, the input flanges  15  have a plurality of holding flanges  25 , and forward  28  and aft  29  bearing surfaces. 
     Spacer ring  20  defines a spacer cavity  106  and has a plurality of platforms  95 . Each platform has a platform bearing surface  100  which functions similarly to the bearing surface  75  of FIG. 2 b . In the assembly&#39;s neutral position, the platform bearing surface  75  is disposed adjacent to the channel and in contact with spring member  30 . 
     FIG. 3 b  is a cross-sectional view along line A—A of FIG. 3 a . Depicted is output member  10 , a pair of input members  15 , and spacer bar  20 . Shown is the spacer platform  95  and platform bearing surface  100 . Platform bearing surface  100  is shown having a curved channel. It is preferred the curved channel has a diameter equal to the outside diameter of spring  30 . As depicted in FIG. 3 c , the platform bearing surface can also have a flat surface area or other geometric configurations. FIG. 3 d  is a cross-sectional view along line B—B of FIG. 3 a . Depicted is output flange  10 , a pair of input flanges  15  and spacer bar  20 . Further depicted is the ledge portion  80  having the ledge bearing surface  85 . As shown, spring  30  is positioned between the bottom wall  105  and the ledge bearing surface  85 . As depicted in FIG. 3 d  the ledge bearing surface  85  can have a flat or curved surface. Spring  30  is also held between the plurality of holding flanges  25 . 
     FIGS. 4 a - 4   c  depict the functioning of the current invention. FIG. 4 a  depicts the current embodiment in a neutral position. FIG. 4 c  depicts the current embodiment subject to torque in the preferred rotational direction. As can be seen, spring  30  is compressed between forward wall  110  and aft bearing surface  29 . Platform  95  is rotated away from recess portion  90  toward the ledge  80 . Bearing surfaces  85  and  100  translate across spring  30 . The ledge portion  80  translates into spacer cavity  106 . It must be noted that there is minimal relative movement between the ledge bearing surface  85  and the spring  30 , reducing wear in this region. 
     As can be seen in FIG. 4 b , torque has been applied to input member  10  in the rotational direction R causing a relative rotational displacement between input member  10  and output member  15 . Spacer platform  95  is shown translated into recess portion  90 . The spring member  30  is compressed between the forward bearing surface  28  and aft wall  115 . As shown, the coved platform bearing surface  100  translates along the top of spring portions  30 . Likewise, the ledge bearing surface  85  translates off the spring  30 . It should be noted that the ledge bearing surface  85  can have a coved or flat structure (as depicted in FIG. 4 b ). The forces from the spring members  30  tend to align output member  10  with parallel input members  15 . 
     Many changes and modifications in the above described embodiment of the invention can, of course, can be carried out without departing from the scope thereof. For instance, elements defined as input members can be used as output members as when the coupling system is used to join two engines. As such, element labels such as input and output members are interchangeable and are not intended to limit the uses of the dual functional elements. Accordingly, that scope is intended to be limited only by the scope of the appended claims.