Abstract:
A damping device that is capable of decreasing torsional vibration may include a driving element and a driven element spaced apart from each other, a receiving groove being shaped as an oval formed along a circular path with a given radius about an axis thereof and formed at the driving element, a carrier which is disposed at the driven element and disposed inside the receiving groove so as to contact an inner part thereof, and a magnetic substance disposed at the carrier, and wherein both sides of the receiving groove are provided with a repulsive force on the magnetic substance in a direction of the center of the receiving groove.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean Patent Application No. 10-2008-0116846 filed on Nov. 24, 2008, the entire contents of which are incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a damping device, and more particularly to a damping device that is capable of decreasing torsional vibration with damping action through repulsive force and contacting a surface intermittently therewith when acceleration from a crankshaft to a nose portion occurs. 
         [0004]    2. Description of Related Art 
         [0005]    Generally, whenever a crankshaft is rotated, a torsional vibration or bending vibration occurs. 
         [0006]    The greater the rotating force of the crankshaft and the longer the length of the crankshaft, or the lower the hardness of the crankshaft, the greater the torsional vibration. 
         [0007]    The torsional vibration causes natural and sympathetic vibration about the crankshaft in the case of exceeding a predetermined rotational speed, and it results in deteriorating ride comfort by extreme vibration, and it damages a timing gear or the crankshaft. 
         [0008]    In order to solve the above problem, a damper pulley that is provided with rubber between an exterior surface of a hub and an interior surface of a ring is used at a front end of the crankshaft, and a separate ring is inserted to the exterior surface of the hub and thereby the length of an engine is long. 
         [0009]    The vibration is absorbed by the rubber disposed between the hub and the ring in the damper pulley. 
         [0010]    When the rotational speed of the crankshaft is constant, the hub is rotated integrally with the crankshaft, however, when the crankshaft generates torsional vibration, the ring tends to rotate continually in a constant speed, and thereby the vibration is reduced by deformation of the rubber disposed therebetween. 
         [0011]    Such a pulley may be a single mass damper pulley, an isolated damper pulley, etc. 
         [0012]    In addition, a double mass damper pulley as a damper pulley is provided with dual belt grooves, and is provided with an outer ring/inner ring at an exterior/interior surface of a hub, such that it forms a dual mode damper pulley. 
         [0013]    Although the single mass damper pulley is a simple structure that is manufactured easily, the damping is deteriorated at a high speed of the engine. 
         [0014]    Further, in spite of an advantage of having damping performance of the isolated damper pulley, it is too expensive and complex to manufacture easily in comparison with the above. 
         [0015]    The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    Various aspects of the present invention are directed to provide a damping device that is capable of decreasing torsional vibration having advantages of damping by repulsive force generated from a magnetic substance in an operating state, damping only by a repulsive force in a high load state, and damping smoothly by intermittent surface contact between a surface of a receiving groove and that of a carrier. 
         [0017]    In an aspect of the present invention, the damping device that is capable of decreasing torsional vibration, may include a driving element and a driven element coaxially coupled each other and spaced apart from each other in an axial direction thereof; a receiving groove formed in the driving element, wherein the receiving groove is shaped as an oval and formed along a circular path with a predetermined radius about a rotational axis thereof; a carrier that is formed on the driven element, and slidably disposed inside the receiving groove of the driving element so as to selectively contact an inner part of the receiving groove according to rotation speed of the driving element; and a first magnetic substance disposed in the carrier, wherein both sides of the receiving groove are provided with a repulsive force acting on the first magnetic substance of the carrier toward a center direction of the receiving groove. 
         [0018]    The first magnetic substance may be divided into S-pole and N-pole respectively approximately by half, and both distal sides of the oval shape of the receiving groove facing the first magnetic substance may include a second magnetic substance having the same magnetic polarity respectively with respect to a facing surface of the first magnetic substance. 
         [0019]    A plurality of the receiving grooves may be provided along the circular path of the driving element and a plurality of the carries formed on the driven element is slidably received therein. 
         [0020]    The first magnetic substance may be formed of a rubber magnet. 
         [0021]    The carrier may be further enclosed by at least one layer of rubber materials having different hardness respectively, wherein the at least one layer of the rubber material is a sponge-type rubber material formed of bubbles. The carrier may be enclosed by a sponge-type rubber material formed of bubbles. 
         [0022]    The receiving groove and the first magnetic substance may be spaced apart from each other in a circumferential direction thereof under one predetermined load condition, and the first magnetic substance contacts a surface of the receiving groove in a rotating direction thereof by a torque exceeding the repulsive force therebetween under another predetermined load condition. 
         [0023]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a cross-sectional view showing a damping device according to various embodiments of the present invention. 
           [0025]      FIG. 2  is a front view showing a damping device according to various embodiments of the present invention. 
           [0026]      FIG. 3A  shows an operation relationship of permanent magnets therebetween in a no load state of a damping device according to various embodiments of the present invention. 
           [0027]      FIG. 3B  shows an operation relationship of permanent magnets therebetween in a low load state of a damping device according to various embodiments of the present invention. 
           [0028]      FIG. 3C  shows an operation relationship of permanent magnets therebetween in a high load state of a damping device according to various embodiments of the present invention. 
           [0029]      FIG. 4A  is a schematic view of a damping device according to another exemplary embodiment of the present invention in a no-load state. 
           [0030]      FIG. 4B  is a schematic view of a damping device according to another exemplary embodiment of the present invention in a low load state. 
           [0031]      FIG. 4C  is a schematic view of a damping device according to another exemplary embodiment of the present invention in a high load state. 
           [0032]      FIG. 5  is a graph showing experimental results of a damping device according to another exemplary embodiment of the present invention. 
           [0033]      FIG. 6A  is a schematic view of a damping device according to a further exemplary embodiment of the present invention. 
           [0034]      FIG. 6B  is a graph showing experimental results of a damping device according to a further exemplary embodiment of the present invention. 
       
    
    
       [0035]    It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
         [0036]    In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0038]      FIG. 1  is a cross-sectional view showing a damping device according to an exemplary embodiment of the present invention. 
         [0039]      FIG. 2  is a front view showing a damping device according to an exemplary embodiment of the present invention. 
         [0040]      FIG. 3A  shows an operation relationship of permanent magnets therebetween in a no load state of a damping device according to an exemplary embodiment of the present invention. 
         [0041]      FIG. 3B  shows an operation relationship of permanent magnets therebetween in a low load state of a damping device according to an exemplary embodiment of the present invention. 
         [0042]      FIG. 3C  shows an operation relationship of permanent magnets therebetween in a high load state of a damping device according to an exemplary embodiment of the present invention. 
         [0043]    As shown in  FIG. 1 , a damping device according to an exemplary of the present invention is driven by a belt  110  of a driving element  100 . 
         [0044]    The damping device is disposed at a driving device, a compressor of an air conditioner, or a generator. 
         [0045]    The damping device includes a driving element  100  and a driven element  200 . 
         [0046]    The driving element  100  and the driven element  200  are rotated on a rolling bearing various embodiments of the present invention, and the like. 
         [0047]    The driven element  200  is provided with a flange  300  and is penetrated by a driving shaft various embodiments of the present invention. 
         [0048]    The driven element  200  and the flange  300  are simultaneously rotated through a clamping cone  310 . 
         [0049]    In this case, the flange  300  is clamped with a clamping screw  320  formed at the end of the clamping cone  310 . 
         [0050]    Further, the driven element  200  faces the driving element  100  such that flange surfaces  120  and  220  are apart from each other and confront each other with a predetermined distance therebetween. 
         [0051]    The flange surfaces  120  and  220  are substantially perpendicular to a rotating shaft of a pulley device P and the flange  300 . 
         [0052]    In addition, a carrier  400  is formed at a circular path C having a smaller radius than a radius of the driven element  200 . 
         [0053]    The carrier  400  is fixed to the circular path C by bolts, etc., and a magnetic substance  410  is formed at a circumference of the carrier  400 . 
         [0054]    Herein, the magnetic substance  410  may be a rubber magnet that is capable of selectively forming an S-pole or an N-pole. 
         [0055]    Further, it is preferable that the shape of the magnetic substance  410  is cylindrical in order to smoothly contact a receiving groove  130 . 
         [0056]    The magnetic substance  410  is formed such that an S-pole  411  and an N-pole  412  respectively occupy half of the magnetic substance  410 . 
         [0057]    Further, a space is defined by the driving element  100  such that the carrier  400  is snugly inserted thereto. 
         [0058]    Thus, the receiving groove  130  is formed at the driving element  100  such that the S-pole  411  and N-pole  412  face each other. 
         [0059]    Referring to  FIG. 2 , although four receiving grooves  130  are shown along the circular path C, the number of receiving grooves  130  can be more than four. 
         [0060]    In addition, it is preferable that each receiving groove  130  is spaced apart from an exterior circumference of the magnetic substance  410  by a predetermined distance such that the magnetic substance  410  is snugly disposed inside the receiving groove  130  that has a shape corresponding to that of the magnetic substance  410 , and further, it is necessary that the radius and area of the receiving groove  130  are greater than those of the magnetic substance  410 . 
         [0061]    Also, surfaces of the receiving groove  130  respectively confronting the S-pole and N-pole may have the same poles formed as rubber, etc. 
         [0062]    That is, the N-pole  412  of the carrier  400  is provided to face an N-pole  132  of the receiving groove  130 , and the S-pole  411  of the carrier  400  is provided to face an S-pole  131  of the receiving groove  130 . 
         [0063]    Therefore, when the driving element  100  is rotated in a direction, the driven element  200  is rotated by a repulsive force caused by magnetic force occurring between the carrier  400  and the receiving groove  130 . 
         [0064]    At this time, if a torque exceeding the repulsive force generated between the carrier  400  and the receiving groove  130  is exerted, the carrier  400  contacts a surface of the receiving groove  130  toward a rotating direction of the carrier  400 . 
         [0065]    Thus, in an idle state as shown in  FIG. 3 , the magnetic substance  410  formed at the carrier  400  disposed inside the receiving groove  130  is spaced apart from the S-pole  131  and the N-pole  132  formed at the receiving groove  130  by the repulsive force. 
         [0066]    Further, as shown in  FIG. 4 , the carrier  400  is biased by an amount of force exceeding the repulsive force generated between the carrier  400  and the receiving groove  130 . 
         [0067]    Meanwhile, in a high load state as shown in  FIG. 5 , since torque of the carrier  400  about a rotating direction exceeds a repulsive force generated between the carrier  400  and the receiving groove  130 , a surface of the carrier  400  contacts a surface of the receiving groove  130 . 
         [0068]    Therefore, in a low load state, a power is transmitted by the repulsive force generated between the carrier  400  and the receiving groove  130 , while in a high load state, the power is transmitted by a contacting force generated therebetween with being supported elastically. 
         [0069]      FIG. 4A  through  FIG. 4C  are cross-sectional views of a carrier formed of rubber materials respectively in no-load condition, a low load condition, and a high load condition. 
         [0070]    The carrier  500  formed of rubber materials may be made of two or more rubber materials having different hardness in order to form a multiple-hardness material. 
         [0071]    As shown in  FIG. 4A , the carrier  500  is maintained in such a state that the carrier  500  does not contact the receiving groove  530 . 
         [0072]    And, as shown in  FIG. 4B , an outer rubber  540  of the carrier  500  contacts the receiving groove  530  so as to receive a portion of a load under a low load condition. 
         [0073]    Further, as shown in  FIG. 4C , an inner rubber  550  formed inside the outer rubber  540  of the carrier  500  receives a load under a high load condition. 
         [0074]      FIG. 5  is a graph showing experimental results of the case in which the two rubbers have different hardness. 
         [0075]    That is, as shown in  FIG. 5 , change of deformation of the carrier is discontinuous, and it is divided into a low load condition area and a high load condition area. 
         [0076]    Meanwhile, as shown in  FIG. 6A , a carrier  600  may be made of a sponge-type rubber having bubbles  610  therein. 
         [0077]    Referring to  FIG. 6B , conversion between a low load condition and a high load condition is smooth through a continuous increase of hardness because of the bubbles  610  inside the receiving groove  630  of the carrier  600 . 
         [0078]    Since the carrier is desirably operable only through changing the material thereof without the S-pole and N-pole as a magnetic member, manufacturing cost thereof can be reduced. 
         [0079]    For convenience in explanation and accurate definition in the appended claims, the terms “interior”, “exterior”, “inner”, and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0080]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.