Patent Publication Number: US-2021179186-A1

Title: Vehicle rear structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2019-0167081, filed on Dec. 13, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicle rear structure, and more particularly, to a vehicle rear structure capable of improving stiffness with respect to a back frame defining a back opening of a vehicle. 
     BACKGROUND 
     In general, a vehicle has a back opening communicating with a luggage compartment or rear compartment in which luggage and the like can be stored. A back door, such as a hatchback door, a trunk lid, a tailgate, or a liftgate, may be installed in the back opening in a manner that opens and closes the back opening. 
     A vehicle body includes a back frame defining the back opening, and the back frame may be defined by a rear edge of a roof panel, rear edges of a pair of side structures, and a top edge of a back panel. 
     When stiffness of the back frame is reduced, vehicle noise may become severe. For example, vehicles with relatively large luggage compartment space, such as hatchback vehicles and wagon vehicles, may suffer from noise due to torsional vibration of the vehicle body. Specifically, the torsional vibration occurs in the power train&#39;s operating range of 1100 to 1300 rpm, and the torsional vibration excites the vehicle body and the back door through a drive shaft, a lower arm, etc., resulting in lock-up booming noise (in automatic transmission vehicles), high-stage low-speed booming noise (in manual transmission vehicles), etc. Here, the vehicle body becomes a transfer system of noise, and the vibration transferred to the back frame and the back door (e.g. a hatchback door, a trunk lid, a tailgate, a liftgate, etc.) may be reduced when a torsional natural frequency of the vehicle body is high. Thus, increasing the torsional natural frequency of the vehicle body is an important consideration in vehicle body design. 
     The following method to increase the torsional natural frequency of the vehicle body as well as improving the stiffness of the back frame has been suggested: a reinforcing member extends straightly from a top end of the back frame toward a wheel housing, and the reinforcing member directly connects the top end of the back frame and the wheel housing. 
     However, such an existing method may increase the weight of the vehicle body, and have a limitation in increasing the torsional natural frequency of the vehicle body or reducing the booming noise. 
     The above information described in this background section is provided to assist in understanding the background of the inventive concept, and may include any technical concept which is not considered as the prior art that is already known to those skilled in the art. 
     SUMMARY 
     The present disclosure has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact. 
     An aspect of the present disclosure provides a vehicle rear structure capable of improving stiffness with respect to a back frame defining a back opening of a vehicle. 
     According to an aspect of the present disclosure, a vehicle rear structure may include: a back frame having a top portion, a bottom portion, a pair of side portions, and a pair of upper corners located on both ends of the top portion, respectively, to define a back opening; and a first reinforcing member extending from each upper corner along a corresponding side portion. The first reinforcing member may include a reinforcing bead and a peripheral flange extending along an edge of the reinforcing bead, and the peripheral flange may be configured to be connected to the corresponding side portion of the back frame. 
     The reinforcing bead may be raised from the peripheral flange, and the reinforcing bead may have a closed cavity. 
     The first reinforcing member may have a flange joined to each upper corner, the reinforcing bead may extend from the flange, and the first reinforcing member may have a closure wall closing a bottom end of the reinforcing bead. 
     The vehicle rear structure may further include a roof reinforcing member connected to the upper corner of the back frame, and the flange of the first reinforcing member may be joined to the roof reinforcing member. 
     A length of the reinforcing bead may be half of a height of the back opening. 
     The first reinforcing member may be L-shaped. 
     The first reinforcing member may have an extension flange tightly contacting and connected to a portion of a side structure of a vehicle body, and the extension flange may be connected to the reinforcing bead. 
     The vehicle rear structure may further include a second reinforcing member extending from the first reinforcing member toward a bottom of a vehicle body, and the second reinforcing member may be connected to the first reinforcing member to intersect at a predetermined angle. 
     The second reinforcing member may extend from the first reinforcing member to a wheel house of a side structure of the vehicle body. 
     The second reinforcing member may have an upper flange connected to the first reinforcing member, and a lower flange connected to the wheel house. 
     The first reinforcing member may further include a matching flange connected to at least a portion of an opening frame of a quarter inner panel in the side structure of the vehicle body, and the opening frame may define a quarter opening of the quarter inner panel. 
     The upper flange of the second reinforcing member may be connected to the first reinforcing member and the opening frame of the quarter inner panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings: 
         FIG. 1  illustrates a perspective view of a vehicle rear structure according to an exemplary embodiment of the present disclosure; 
         FIG. 2  illustrates an enlarged view of an upper corner of a back frame and a side portion connected thereto in the vehicle rear structure of  FIG. 1 ; 
         FIG. 3  illustrates an enlarged view of portion A of  FIG. 2 ; 
         FIG. 4  illustrates a perspective view which is viewed in a direction indicated by arrow B of  FIG. 2 ; 
         FIG. 5  illustrates a cross-sectional view taken along line C-C of  FIG. 4 ; and 
         FIG. 6  illustrates a cross-sectional view taken along line D-D of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals will be used throughout to designate the same or equivalent elements. In addition, a detailed description of well-known techniques associated with the present disclosure will be ruled out in order not to unnecessarily obscure the gist of the present disclosure. 
     Terms such as first, second, A, B, (a), and (b) may be used to describe the elements in exemplary embodiments of the present disclosure. These terms are only used to distinguish one element from another element, and the intrinsic features, sequence or order, and the like of the corresponding elements are not limited by the terms. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted as having ideal or excessively formal meanings unless clearly defined as having such in the present application. 
     Referring to  FIG. 1 , a vehicle rear structure according to an exemplary embodiment of the present disclosure may include a back frame  11  defining a back opening  13 . The back frame  11  may be defined by a top structure  1 , a pair of side structures  2 , and a back structure  3 . In particular, the back frame  11  may be defined by a rear edge of the top structure  1 , rear edges of the pair of side structures  2 , and a top edge of the back structure  3 . The back opening  13  may communicate with a luggage compartment or rear compartment in which luggage and the like are received, and a back door such as a hatchback door, a trunk lid, a tailgate, or a liftgate may be installed in the back opening  13  in a manner that opens and closes the back opening  13 . 
     According to an exemplary embodiment, the top structure  1  may include a roof panel (not shown) and a rear roof rail  14  connected to a rear edge of the roof panel. Each side structure  2  may include a quarter inner panel  15  and a side outer panel (not shown) covering the quarter inner panel  15 . The back structure  3  may include an inner back panel  16  connected to a lower portion of the quarter inner panel  15  and an outer back panel (not shown) covering the inner back panel  16 . 
     The quarter inner panel  15  may have a quarter opening  15   a  in which quarter glass is mounted, and an opening frame  15   b  defining the quarter opening  15   a . The opening frame  15   b  may be raised from an exterior surface of the quarter inner panel  15  toward the exterior of the vehicle, and the raised opening frame  15   b  may increase stiffness of the quarter inner panel  15 . A wheel house  19  protecting a wheel may be integrally connected to the lower portion of the quarter inner panel  15 . For example, the quarter inner panel  15  may be divided into an upper panel and a lower panel, and the inner back panel  16  may be integrally connected to the lower panel. 
     The back frame  11  may have a top portion  11   a , a pair of side portions  11   b  and  11   c , a bottom portion  11   d , and a pair of upper corners  12  and  18  located on both ends of the top portion  11   a , respectively. The top portion  11   a  may be defined in a longitudinal direction of the rear roof rail  14 . The side portions  11   b  and  11   c  may be defined along the rear edges of the side structures  2 , respectively. The bottom portion  11   d  may be defined along the top edge of the back structure  3 . Each end portion of the rear roof rail  14  and a top end of each quarter inner panel  15  may be connected so that each of the upper corners  12  and  18  may be defined by the end portion of the rear roof rail  14  and the top end of the quarter inner panel  15 . Each of the upper corners  12  and  18  and each of the side portions  11   b  and  11   c  in the back frame  11  may be reinforced by a first reinforcing member  21  and a second reinforcing member  22 .  FIG. 1  illustrates the first reinforcing member  21  and the second reinforcing member  22  which are mounted on the left upper corner  12  and the left side portion  11   b , but the first reinforcing member  21  and the second reinforcing member  22  may also be mounted on the right upper corner  18  and the right side portion  11   c  in the same manner. 
     The first reinforcing member  21  may extend from each of the upper corners  12  and  18  along the corresponding side portions  11   b  and  11   c , and the first reinforcing member  21  may be L-shaped. The end portions of the rear roof rail  14  may be located on the upper corners  12  and  18  of the back frame  11 , respectively, and thus each end portion of the rear roof rail  14  may form a portion of each upper corner of the back frame  11 , respectively. Specifically, the first reinforcing member  21  may extend from each end portion of the rear roof rail  14  along a rear edge of the quarter inner panel  15 . 
     The first reinforcing member  21  may have a flange  23  extending from a top end thereof, and the flange  23  may be joined to each upper corner of the back frame  11  by welding and/or the like. 
     A roof reinforcing member  41  may be connected to each upper corner of the back frame  11 . In particular, the roof reinforcing member  41  may be connected to the rear edge of the top structure  1 . Specifically, the roof reinforcing member  41  may be joined to each end portion of the rear roof rail  14  by welding and/or the like, thereby increasing stiffness of the rear roof rail  14  as well as connecting the end portion of the rear roof rail  14  and the top end of the quarter inner panel  15 . The flange  23  of the first reinforcing member  21  may be overlapped and joined to at least a portion of the roof reinforcing member  41 . At least a portion of the roof reinforcing member  41  may be interposed between the flange  23  of the first reinforcing member  21  and the rear roof rail  14  so that stiffness of the upper corners  12  and  18  of the back frame  11  may be improved. 
     The first reinforcing member  21  may have a peripheral flange  31  joined to the rear edge of the quarter inner panel  15  (that is, the side portions  11   b  and  11   c  of the back frame  11 ), and a reinforcing bead  32  raised from the peripheral flange  31  toward the exterior of the vehicle. The peripheral flange  31  may surround the reinforcing bead  32  along the edge of the first reinforcing member  21 . The peripheral flange  31  may extend flat so that it may be joined to the rear edge of the quarter inner panel  15 . 
     Referring to  FIGS. 3 and 6 , the reinforcing bead  32  may have a flat surface  32   a  and an inclined surface  32   b  extending obliquely from the peripheral flange  31  toward the flat surface  32   a , and thus the reinforcing bead  32  may have a cavity  32   d  therein. The first reinforcing member  21  may have a closure wall  25  closing a bottom end of the reinforcing bead  32 , and the peripheral flange  31  may be joined to the quarter inner panel  15  so that the cavity  32   d  of the reinforcing bead  32  may be a closed cavity which is completely closed with respect to the outside by the closure wall  25 . The first reinforcing member  21  may increase stiffness with respect to each of the upper corners  12  and  18  and each of the side portions  11   b  and  11   c  of the back frame  11  using the reinforcing bead  32 . 
     The first reinforcing member  21  may include an extension flange  33  tightly joined to the exterior surface of the quarter inner panel  15 . The extension flange  33  may extend from the flange  23  and the reinforcing bead  32  of the first reinforcing member  21  toward the opening frame  15   b  of the quarter inner panel  15 . In addition, the extension flange  33  may be connected by the flat surface  32   a  of the reinforcing bead  32  and a connection wall  32   c . The extension flange  33  may be joined to an upper exterior surface  15   c  of the quarter inner panel  15  by welding and/or the like. 
     Referring to  FIGS. 5 and 6 , the extension flange  33  may have a surface that matches the upper exterior surface  15   c  of the quarter inner panel  15  so that the extension flange  33  and the upper exterior surface  15   c  of the quarter inner panel  15  may tightly contact and be joined. 
     The first reinforcing member  21  may further include a matching flange  34  connected to at least a portion of the opening frame  15   b  of the quarter inner panel  15 . The matching flange  34  may be integrally connected to the extension flange  33 , and the matching flange  34  may have a cross section matching that of the opening frame  15   b.    
     The reinforcing bead  32  of the first reinforcing member  21  may extend from the flange  23  by a predetermined length. The length of the reinforcing bead  32  may be half (H/2) of a total height H of the back opening  13 . That is, the first reinforcing member  21  may be attached to upper areas of the side portions  11   b  and  11   c  of the back frame  11 , thereby improving support stiffness and torsional stiffness with respect to the upper corners  12  and  18  and the side portions  11   b  and  11   c  of the back frame  11 . 
     Referring to  FIGS. 1 and 2 , the second reinforcing member  22  may extend from the first reinforcing member  21  toward the bottom of the vehicle body. The second reinforcing member  22  may intersect with the first reinforcing member  21  at a predetermined angle, and the second reinforcing member  22  may be joined to each side structure  2  by welding and/or the like. 
     Referring to  FIGS. 1 and 2 , the second reinforcing member  22  may extend from the first reinforcing member  21  to the wheel house  19  integrally formed with the lower portion of the quarter inner panel  15 . The second reinforcing member  22  may be disposed to intersect with each of the side portions  11   b  and  11   c  of the back frame  11  at a predetermined angle, thereby firmly supporting each of the side portions  11   b  and  11   c  of the back frame  11 . Specifically, the second reinforcing member  22  may intersect with the reinforcing bead  32  of the first reinforcing member  21  at a predetermined angle, and the first reinforcing member  21  may be connected to the quarter inner panel  15  and the wheel house  19  of the side structure  2  of the vehicle body by the second reinforcing member  22 , whereby the support stiffness and torsional stiffness of the upper corners  12  and  18  and the side portions  11   b  and  11   c  of the back frame  11  may be significantly improved. 
     Referring to  FIGS. 1 and 2 , the second reinforcing member  22  may have an upper flange  24  connected to the first reinforcing member  21  and a lower flange  26  connected to the wheel house  19 . Referring to  FIG. 3 , the upper flange  24  of the second reinforcing member  22  may be connected to the first reinforcing member  21  and the opening frame  15   b  of the quarter inner panel  15  adjacent thereto. As the second reinforcing member  22  connects the first reinforcing member  21  and the wheel house  19 , a load applied to the upper corner  12  of the back frame  11  may be uniformly distributed. 
     According to exemplary embodiments of the present disclosure, the first reinforcing member  21  and the second reinforcing member  22  may structurally connect and support the upper corners  12  and  18  and the side portions  11   b  and  11   c  of the back frame  11 , thereby increasing stiffness with respect to the upper corners  12  and  18  and the side portions  11   b  and  11   c  of the back frame  11 , and thus improving torsional natural frequency and lock-up booming (high-stage low-speed booming). For example, the torsional natural frequency may be improved by about 5 Hz, and the lock-up booming (high-stage low-speed booming) may be improved by about 6 dB. 
     According to exemplary embodiments of the present disclosure, by applying a structure in which the second reinforcing member  22  intersects with the first reinforcing member  21  at a predetermined angle, the overall length of the first reinforcing member  21  and the second reinforcing member  22  may be reduced, and thus weight reduction and cost reduction may be achieved. 
     As set forth above, according to exemplary embodiments of the present disclosure, the upper corners and the side portions of the back frame may be structurally connected and supported by the first reinforcing member and the second reinforcing member, and thus stiffness with respect to the upper corners and the side portions of the back frame may be significantly improved, and the torsional natural frequency and the booming noise reduction may be improved. 
     According to exemplary embodiments of the present disclosure, the overall length of the first reinforcing member and the second reinforcing member may be reduced, and thus the weight reduction and cost reduction may be achieved. 
     Hereinabove, although the present disclosure has been described with reference to exemplary embodiments and the accompanying drawings, the present disclosure is not limited thereto, but may be variously modified and altered by those skilled in the art to which the present disclosure pertains without departing from the spirit and scope of the present disclosure claimed in the following claims.