Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority of Korean Patent Application Number 10-2013-0164099 filed on Dec. 26, 2013, the entire contents of which application are incorporated herein for all purposes by this reference. 
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to a pulley structure and a damper pulley. More particularly, the present invention relates to a pulley structure and a damper pulley which are prevented from corroding due to a potential difference. 
     2. Description of Related Art 
     In general, a damper pulley is directly fitted on a crankshaft and rotates with it to be able to directly receive torque from the crankshaft that are rotated by an engine. The damper pulley transmits the torque of the engine from the crankshaft to accessories such as a water pump, a power steering system, and an air conditioner. 
     The damper pulley is formed by combining a hub part, which is fitted on a crankshaft rotated by power from an engine and rotates with it, with a pulley part, which rotates with the hub and is connected with a power transmission member. The hub part and the pulley part may be bolted. When the hub part and the pulley part are bolted, the pulley part that is made of an aluminum alloy or a magnesium alloy and coupling members such as bolts that are made of steel are in contact with each other. 
     However, when the pulley part made of an aluminum alloy or a magnesium alloy, a side of the hub part made of steel, and the coupling members made of steel are in direction contact with each other, corrosion may be caused by the potential difference between two different metallic materials. 
     The information disclosed in this Background 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. 
     SUMMARY OF INVENTION 
     The present invention has been made in an effort to provide a pulley structure and a damper pulley having advantages of being prevented from corroding due to the potential difference between constituent elements. 
     Various aspects of the present invention provide a pulley structure including a hub part that is fitted on a crankshaft rotated by power from an engine and rotates with the crankshaft and a pulley part coupled with the hub part to rotate with the hub part and connected with a power transmission member. The hub part may include a pulley contact surface facing the pulley part, and pulley coupling portions formed at the pulley contact surface to secure coupling members. The pulley part may include a hub contact surface facing the pulley contact surface of the hub part, hub coupling portions coupled to the pulley coupling portions by securing the coupling members, and coupling grooves recessed from the hub coupling portions to insert the coupling members. Washers made of an insulator may be fitted on the coupling members between the pulley coupling portions and the hub coupling portions. 
     The washers may be pressed by the pulley coupling portions and the hub coupling portions and may be elastically deformed to prevent liquid from flowing into the coupling grooves. The hub coupling portions may protrude at a predetermined level from the hub contact surface. 
     Various other aspects of the present invention provide a damper pulley including a hub part that is fitted on a crankshaft rotated by power from an engine and rotates with the crankshaft and a pulley part coupled with the hub part to rotate with the hub part and connected with a power transmission member. The hub part may include an outer ring coupled with the pulley part, an inner ring disposed inside the outer ring, a damper rubber disposed between the outer ring and the inner ring, a pulley contact surface on the outer ring facing the pulley part, and pulley coupling portions formed at the pulley contact surface so that coupling members pass through the outer ring. The pulley part may include a hub contact surface facing the pulley contact surface of the hub part, hub coupling portions coupled to the pulley coupling portions by securing the coupling members, and coupling grooves recessed from the hub coupling portions to insert the coupling members. A molding made of an insulator may be coated on the pulley contact surface. 
     The hub coupling portions may protrude at a predetermined level from the hub contact surface. The molding may extend from the damper rubber between the outer ring and the inner ring of the hub part to cover the pulley contact surface. 
     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, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view showing an exemplary damper pulley according to the present invention. 
         FIG. 2A  is a perspective view showing an exemplary assembled damper pulley according to the present invention. 
         FIG. 2B  is a partially enlarged view of  FIG. 2A . 
         FIG. 3  is an exploded perspective view showing another exemplary damper pulley according to the present invention. 
         FIG. 4  is a perspective view showing an exemplary pulley part according to the present invention. 
         FIG. 5  is a cross-sectional view showing another exemplary assembled damper pulley according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
       FIG. 1  is an exploded perspective view showing a damper pulley according to an exemplary embodiment of the present invention. As shown in  FIG. 1 , a damper pulley according to an exemplary embodiment of the present invention includes a hub part  10  and a pulley part  20 . 
     In this specification, the combination and contact of the hub part  10  and the pulley part  20  are described and the basic configurations of the hub part  10  and the pulley part  20  of the damper pulley are illustrated in the figures. 
     The hub part  10  has a pulley contact surface  12  and pulley coupling portions  15 . The pulley contact surface  12  is the side that is brought in contact with the pulley part  20 . The shape of the pulley contact surface  12  is the shape of a circular or a substantially circular disc fitting to or in accord with the shape of the hub part  10 . Further, the pulley contact surface  12  is formed in the shape of a hollow disc so that the constituent elements of the hub part  10  are disposed radially inside. The pulley contact surface  12  is a side of the wing, which radially extends, of an outer ring  14  of the hub part  10 . Examples of the outer ring  14  of the hub part  10  and the wing of the outer ring  14  are illustrated in the figures. 
     The pulley coupling portions  15  may be grooves recessed radially inward from the outer circumference of the pulley contact surface  12 . That is, they are recessed from the outer circumference of the wing of the outer ring  14 . Further, a plurality of pulley coupling portions  15  is formed around the pulley contact surface  12 . The pulley coupling portions  15  may be arranged with regular intervals along the circumference of the hub part  10  and the pulley contact surface  12 . The hub part  10  and the pulley part  20  are combined by securing the coupling members  30  to the pulley part  20  through the pulley coupling portions  15  (see  FIGS. 2A and 2B ). Although the pulley coupling portions  15  are formed in the shape of a groove recessed from the outer circumference of the pulley contact surface  12 , they are not limited thereto and may be formed in the shape of a circular or substantially circular hole through which the coupling members  30  are inserted. For example, the coupling members  30  may be bolts or rivets. 
     The pulley part  20  has a hub contact surface  22 , hub coupling portions  25 , and coupling grooves  27 . 
     The hub contact surface  22  is a side that is brought in contact with the pulley contact surface  12  of the hub part  10 . Further, the hub contact surface  22  is formed in the shape of a hollow circle or a substantially hollow circle fitting to or in accord with the shape of the pulley part  20 . That is, the hub contact surface  22  is a side of the pulley part  20  formed in the shape of a hollow cylinder. 
     The hub coupling portions  25  are coupled to the pulley coupling portions  15 . Further, the hub coupling portions  25  protrude from the hub contact surface  22 . A plurality of hub coupling portions  25  may be formed around the hub contact surface  22 . The hub coupling portions  25  may be formed with regular intervals, corresponding to the positions of the pulley coupling portions  15  and the pulley coupling portions  15  are formed at least as many as the hub coupling portions  25 . 
     The coupling grooves  27  are recessed in the axial direction of the pulley part  20  from the hub coupling portions  25 . The hub part  10  and the pulley part  20  are combined by securing the coupling members  30  into the coupling grooves  27  through the pulley coupling portions  15  (see  FIGS. 2A and 2B ). 
       FIG. 2A  is a perspective view showing an assembled damper pulley according to an exemplary embodiment of the present invention.  FIG. 2B  is a partially enlarged view of  FIG. 2A . As shown in  FIGS. 2A and 2B , when the coupling member  30  is inserted into the coupling groove  27  through the pulley coupling portion  15  of the outer ring  14 , a washer  17  is disposed between the pulley contact surface  12  and the hub contact surface  22 . That is, the washer  17  is disposed between the pulley coupling portion  15  and the hub coupling portion  25 . 
     The washer  17  is made of an insulator. For example, the washer  17  may be made of plastic or rubber. Further, the washer  17  may be formed in the shape of a ring so that the coupling member  30  passes through it. Since the plastic washers  17  are disposed between the pulley coupling portions  15  and the hub coupling portions  25 , direct contact between the coupling portions  25  of the pulley part  20  and the coupling members  30  is prevented. Further, direct contact between the hub coupling portions  25  of the pulley part  20  and the outer ring  14  is prevented. Accordingly, corrosion of the pulley part  20 , the coupling members  30 , and the outer ring  14  due to the potential difference between the pulley part  20  made of an aluminum alloy or a magnesium alloy and the coupling members  30  and the outer ring  14  that are made of steel can be prevented. The washers  17  between the pulley coupling portions  15  and the hub coupling portions  25  are pressed by securing the coupling members  30 , such that liquid that corrodes metal is prevented from flowing into the coupling grooves  27  by the close-contact force due to elastic deformation of the washers  17 . 
       FIG. 3  is an exploded perspective view showing a damper pulley according to another exemplary embodiment of the present invention. As shown in  FIG. 3 , the damper pulley according to another exemplary embodiment of the present invention further includes a molding in comparison to the damper pulley according to the previous exemplary embodiment of the present invention. 
     The molding  19  is made of an insulator. For example, the molding  19  may be made of rubber. The molding  19  is coated or overlaid on the pulley contact surface  12 . The molding  19  may extend to cover the pulley contact surface  12  from a damper rubber  18  disposed between the outer ring  14  of the hub part  10  and the inner ring  11  inside the outer ring  14 . Examples of the outer ring  14 , inner ring  11 , and the damper rubber  18  of the hub part  10  are illustrated in the figures. 
     Pulley coupling portions  15  formed in the shape of a circular hole or a substantially a circular hole, as described above, are shown in  FIG. 3 . 
       FIG. 4  is a perspective view showing a pulley part according to exemplary embodiments of the present invention. As shown in  FIG. 4 , the hub coupling portions  25  protrude at a predetermined level from the hub contact surface  22 . Protruding the hub coupling portions  25  from the hub contact surface  22  is for prevent liquid that corrodes metal from flowing into the coupling grooves  27 . 
       FIG. 5  is a cross-sectional view showing the assembled damper pulley according to another exemplary embodiment of the present invention. As shown in  FIG. 5 , when the hub part  10  and the pulley part  20  are combined, direct contact between the pulley part  20  made of an aluminum alloy or a magnesium alloy and the coupling members  30  and the outer ring  14  that are made of steel is prevented by the molding  19  coated on the pulley contact surface  12 . Accordingly, corrosion of the pulley part  20 , the coupling members  30 , and the outer ring  14  due to the potential difference between the pulley part  20  and the coupling members  30  or the pulley part  20  and the outer ring  14  can be prevented. 
     Since the molding  19  is provided in this exemplary embodiment of the present invention, the washers  17  may not be provided, as compared with the previous exemplary embodiment of the present invention. Further, in various embodiments of the present invention, since corrosion due to the potential difference between the pulley part  20 , the coupling members  30 , and the outer ring  14  is prevented, the pulley part  20  made of an aluminum alloy or a magnesium alloy can be used without difficulty. When the pulley part  20  is made of an aluminum alloy or a magnesium alloy, the entire weight of the damper pulley reduces as compared with when the pulley part  20  is made of steel. 
     As described above, according to various embodiments of the present invention, since the washer  17  are disposed to prevent one side of the hub part  10  and the coupling members  30  from coming in direct contact with the pulley part  20 , corrosion due to a potential difference can be prevented. Further, since the side of the hub part  10  that may come in direct contact with the pulley part  20  is coated, corrosion due to a potential difference can be prevented. 
     For convenience in explanation and accurate definition in the appended claims, the terms “inner” or “outer”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     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.

Technology Category: f