Abstract:
A weather strip for attachment to a window frame of a vehicle for sealing the- periphery of a window and a method of forming the weather strip. The weather strip supports the window to allow the window to slide upward and downward with respect to the window frame. The weather strip includes an elongated side section for attachment to a generally vertical member of the window frame, an elongated upper section for attachment to a horizontal member of the frame, and a corner section for attachment to a corner of the window frame. The weather strip includes an inner seal lip and an outer seal lip, which resiliently contact the inner and outer surfaces of the window, respectively. The cross sectional shapes of the seal lips vary from the side section to the upper section, yet the inner and outer seal lips are formed of a single continuous extrusion.

Description:
The application is a continuation of Ser. No. 08/985,394 Dec. 8, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to weather strips attached to door window frames of vehicles for guiding door windows and methods of forming such weather strips. 
     2. Description of the Related Art 
     Weather strips, with which door windows engage, are typically attached to door window frames of vehicles. The weather strip guides the door window and seals between the door window frame and the door window against rainwater or the like. A typical weather strip  109  is shown in FIG.  15 . The weather strip  109  includes front and rear side parts  101  shown in FIG.  15 ( a ), an upper part  102  shown in FIG.  15 ( b ), and a connecting part (not shown). The connecting part connects the side parts  101  with the upper part  102 . FIGS.  15 ( a ) and  15 ( b ) are cross-sectional views showing the side part  101  and the upper part  102 , respectively. The side part  101  includes an inner seal lip  104  and an outer seal lip  105 . The inner seal lip  104  resiliently contacts an inner surface  103   a  of the door window  103  at a front or rear edge. The outer seal lip  105  resiliently contacts an outer surface  103   b  of the door window  103  at a front or rear edge. 
     An auxiliary lip  106  extends from the proximal portion of the outer lip  105 . The auxiliary lip  106  reduces whistling of wind passing through a clearance  110 , which is defined between the door window  103  and the outer seal lip  105 . Furthermore, the auxiliary lip  106  improves the rigidity of the outer seal lip  105  and prevents the outer seal lip  105  from deforming toward the exterior of the vehicle when the window  103  moves. The side part  101  is extruded to have a uniform cross section. 
     The structure of the upper part  102  is almost the same as that of the side part  101  except for the auxiliary lip  106 . The upper part  102  includes an inner seal lip  107  and an outer seal lip  108 . The inner seal lip  107  resiliently contacts the inner surface  103   a  of the door window  103  at an upper edge, while the outer seal lip  108  resiliently contacts the outer surface  103   b  of the door window  103  at the upper edge. 
     No auxiliary lip  106  extends from the outer seal lip  108 . This prevents the window  103  from catching the auxiliary lip  106  while moving upward between the inner seal lip  107  and the outer seal lip  108 . The inner seal lip  107  of the upper part  102  is larger than the inner seal lip  104  of the side part  101 . This improves the rigidity of the inner seal lip  107 . The inner seal lip  107  is also resilient to guide the window  103 , which moves upward between the inner seal lip  107  and the outer seal lip  108 , to a predetermined position indicated by the double dotted chain line in FIG.  15 ( b ). The upper part  102  is also extruded to have a uniform cross section. 
     The connecting part corresponds to a corner of the window  103  and connects the side part  101  with the upper part  102 . The connecting part  101  is formed through injection molding or the like. 
     The weather strip  109  includes at least three members, that is, the front and rear side parts  101 , the upper part  102 , and the connecting part. Manufacture of these members requires independent molds, such as an extruder and an injection molding for separately forming the side parts  101 , the upper part  102 , and the connecting part. Furthermore, to form the weather strip  109 , the front and rear side parts  101 , and the upper part  102 , each of which has been extruded independently, must be connected to one another by the connecting part (at the front upper corner and the rear upper corner). Therefore, at least four types of molds (two types of extrusion molding dies and two types of injection molds) are necessary to manufacture the conventional weather strip  109 . This complicates the manufacturing equipment. Furthermore, since four or more parts must be formed separately, the number of manufacturing steps is increased. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a one-piece extruded weather strip having a variable cross sectional shape. A further object is to simplify the equipment and method for manufacturing the weather strip. 
     To achieve the above objects, a weather strip for attachment to a window frame of a vehicle is provided in a first aspect of the present invention. The weather strip contacts a surface of the window for sealing a periphery of the window. The weather strip guides the window while allowing the window to slide upward and downward with respect to the window frame. The weather strip includes an elongated side section for attachment to a generally vertical member of the window frame, an elongated upper section for attachment to a generally horizontal member of the window frame, and a corner section for attachment to a corner of the window frame. All sections are formed integrally and continuously. A continuous seal lip extrusion resiliently contacts a surface of the window. The seal lip forms part of and is coextensive with the side section, the corner section, and the upper section. The cross sectional shape of the seal lip extrusion varies from a first shape along the side section to a second shape along the upper section such that the seal has different sealing characteristics along the side section as compared to the sealing characteristics of the upper section. A transition shape between the first shape and the second shape is formed in the corner section. 
     In a second aspect of the present invention, a weather strip for attachment to a window frame of a vehicle is provided. The weather strip contacts both an inner surface and an outer surface of the window. The weather strip supports the window while allowing the window to slide upward and downward with respect to the window frame. The weather strip includes an elongated side section for attachment to a generally vertical member of the window frame, an elongated upper section for attachment to a generally horizontal member of the window frame, and a corner section for attachment to a corner of the window frame. All sections are formed integrally and continuously. A continuous inner seal lip extrusion resiliently contacts the inner surface of the window. The inner seal lip forms part of and is coextensive with the side section, the corner section, and the upper section. The cross sectional shape of the inner seal lip varies from the upper section to the side section. A continuous outer seal lip extrusion resiliently contacts the outer surface of the window. The outer seal lip forms part of and is coextensive with the side section, the corner section, and the upper section. The cross sectional shape of the outer seal lip varies from the upper section to the side section. The outer lip seal is parallel to the inner lip seal. 
     In a third aspect of the present invention, a method of extruding a weather strip for a vehicle window frame is provided. The method includes the step of extruding a single weather strip by an extruder, the cross sectional shape of which varies longitudinally. The weather strip includes a side section for attachment to a generally vertical member of the window frame, a corner section for attachment to a corner of the frame, and an upper section for attachment to a generally horizontal member of the frame. The corner section lies between and is integral with the upper section and the side section. The extruding step includes extruding the inner and the outer seal lips to be coextensive with the side section, the corner section, and the upper section. The inner seal lip is initially extruded with a first cross sectional shape. The extruding step also includes changing the cross sectional area of the inner seal lip to form a second cross sectional shape by changing the size of a molding die opening of the extruder after a predetermined time such that the seal lip extending along the upper section has different sealing characteristics than that extending along the side section, and forming a transition between the first cross sectional shape and the second cross sectional shape on the corner section by performing the step of changing the size of the molding die opening while extruding the corner section. 
     Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
     FIG. 1 is a perspective view showing a rear corner of a first embodiment of a weather strip according to the present invention; 
     FIG. 2 is a side view showing a vehicle door including the weather trip attached to a door window frame; 
     FIG. 3 is an enlarged cross-sectional view of a side section of the weather strip taken along the line III—III of FIG. 2; 
     FIG. 4 is an enlarged cross-sectional view of an upper section of the weather strip taken along the line IV—IV of FIG. 2; 
     FIG. 5 is a front view showing the relationship between a fixed molding die and two movable dies when extruding the side section of the weather strip of FIG. 3; 
     FIG. 6 is a front view showing the relationship between the fixed molding die and the movable dies when extruding the upper section of the weather strip of FIG. 4; 
     FIG. 7 is an enlarged cross-sectional view showing an upper section of a weather strip according to a second embodiment; 
     FIG. 8 is a front view showing the relationship between the position of an opening and the position of movable dies for extruding the upper section of the weather strip of FIG. 7; 
     FIG. 9 is a perspective cross-sectional view taken along the line IX—IX in FIG. 8; 
     FIG. 10 is an enlarged cross-sectional view showing a side section of a weather strip according to a third embodiment; 
     FIG. 11 is a front view showing the relationship between a fixed molding die and movable dies for extruding the side section of the weather strip of FIG. 10; 
     FIG. 12 is a perspective view showing a corner section of a weather strip according to a fourth embodiment; 
     FIG. 13 is an enlarged cross-sectional view taken along the line XIII—XIII in FIG. 12; 
     FIG. 14 is a perspective view showing a further embodiment of a corner section of a weather strip; 
     FIG.  15 ( a ) is a cross-sectional view showing a side part of a weather strip of a conventional type; and 
     FIG.  15 ( b ) is a cross-sectional view showing an upper part of the weather strip of the conventional type. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     (First embodiment) 
     A one-piece weather strip according to a first embodiment of the present invention will now be described with reference to FIGS. 1 to  6 . 
     As shown in FIG. 2, a door  11  of a vehicle includes a door body  12 , a door window frame  13  arranged above the body  12 , and a door window  14 , which moves upward and downward. The frame  13  is slightly inclined with respect to the plane of the sheet of FIG.  2 . The window  14  moves upward and downward along the frame  13 . 
     An integral weather strip  15 , which is formed of ethylene propylene diene copolymer (EPDM), is attached to the inner edge of the door window frame  13 . The weather strip  15  is substantially linear before being attached to the frame  13 . However, when attached to the frame  13 , the weather strip  15  is shaped in correspondence with the shape of the frame  13 . Specifically, the one piece weather strip  15  includes a front side section  16 , a rear side section  20 , an upper section  18 , a front corner section  17 , and a rear corner section  19 . The side sections  16 ,  20  extends along the front and rear edges of the window  14  and along the direction of movement of the window  14  (in a substantially vertical direction as viewed in FIG.  2 ). The upper section  18  extends horizontally along the top edge of the window  14 . 
     The front corner section  17  is integral with the front side section  16  and the front end of the upper section  18 , while the rear corner section  19  is integral with the rear side section  20  and the rear end of the upper section  18 . 
     As shown in FIG. 3, each side section  16 ,  20  includes a base  21 , a pair of side walls  22 , an inner seal lip  23 , and an outer seal lip  24 . The side walls  22  extend parallel to each other and project from opposite ends of the base  21 . The seal lips  23 ,  24  project from the distal ends of the associated side walls  22 . Each lip  23 ,  24  is curved inwardly to extend toward the base  21 . The inner seal lip  23  resiliently contacts an inner side surface of the window  14  (hereafter referred to as an inner surface  14   a ). The outer lip  24  resiliently contacts an outer side surface of the window  14  (hereafter referred to as an outer surface  14   b ). Each lip  23 ,  24  is tapered to narrow toward its edge. Furthermore, an auxiliary lip  25  projects from the proximal portion (the portion connected with the associated outer side wall  22 ) of the outer seal lip  24  (projecting downwardly to the left as viewed in FIG.  3 ). The auxiliary lip  25  increases the rigidity of the proximal portion of the outer seal lip  24  to increase the pressing force applied by the outer seal lip  24  to the window  14 . Furthermore, the auxiliary lip  25  prevents wind stream from passing through a clearance  26 , which is defined between the outer seal lip  24  and the window  14 . 
     As shown in FIG. 4, the upper section  18  includes a base  27 , a pair of side walls  28 , an inner seal lip  29 , and an outer lip  30 . The side walls  28  are parallel to each other, each projecting from one end of the base  27 . The seal lips  29 ,  30  project from the distal ends of the associated side walls  28  and are curved inwardly to extend toward the base  27 . The inner seal lip  29  resiliently contacts an upper part of the inner surface  14   a  of the window  14 . The outer seal lip  30  resiliently contacts an upper part of the outer surface  14   b  of the window  14 . Each lip  29 ,  30  is tapered to narrow toward its distal edge. There is no auxiliary lip  25  on the proximal portion of the outer seal lip  30 . The inner seal lip  29  is larger than the corresponding inner seal lip  23  of the side sections  16 ,  20 . Specifically, the inner seal lip  29  has additional material on its lower edge, as indicated by the chain line in FIG. 4 (which delineates the shape of the corresponding inner seal lip  23  of the side sections  16 ,  20  for comparison). 
     As shown in FIG. 1, the rear corner section  19  includes a base  31 , a pair of side walls  32 , an inner seal lip  33 , and an outer seal lip  34 . The side walls  32  extend parallel to each other, each projecting from one end of the base  31 . Each seal lip  33 ,  34  projects inwardly from the distal end of the associated side wall  32  to extend toward the base  31 . The inner seal lip  33  resiliently contacts the inner surface  14   a  along a corner  36  (see FIG. 2) of the window  14 , while the outer seal lip  34  resiliently contacts the outer surface  14   b  along the corner  36  of the window  14 . 
     An auxiliary lip  35  projects from the proximal portion of the outer seal lip  34  in the same manner as the auxiliary lip  25  of each side section  16 ,  20 . However, the projecting distance of the auxiliary lip  35  varies along the outer seal lip  34 . Specifically, such distance is maximum (equal to that of the auxiliary lip  25  of the side sections  16 ,  20 ) at an end of the rear corner section  19  adjacent to rear the side section  20 . The projecting distance decreases toward the upper section  18  and becomes minimum (zero) at the end of the rear corner section  19  that is adjacent to the upper section  18 . 
     Furthermore, the inner seal lip  33  becomes larger at locations nearer to the end adjacent to the upper section  18 . Specifically, the inner seal lip  33  is the largest (equal to that of the inner seal lip  29  of the upper section  18 ) at an end of the rear corner section  19  adjacent to the upper section  18 . The inner seal lip  33  becomes smaller toward the rear side section  20  and becomes the smallest (equal to that of the inner seal lip  23 ) at the end of the rear corner section  19  adjacent to the rear side section  20 . 
     The front corner section  17  has the same structure as the illustrated rear corner section  19 . Thus, to avoid redundancy, the front corner section  17  will not be described. Furthermore, to decrease resistance to the sliding of the window  14 , lubricating agents such as urethane and silicone are applied to the surfaces of the lips  23 ,  24 ,  29 ,  30 ,  33 ,  34 . Alternatively, a lubricating layer formed of polyethylene resin or a brush may be employed instead of the lubricating agent. 
     The integral weather strip  15  described above is formed by means of extrusion molding. The method for extrusion molding the weather strip  15  is disclosed in U.S. patent application No. 08/885195 (filed by the co-assignee of the present application) and is incorporated herein by reference. This method employs, as shown in FIGS. 5 and 6, a fixed molding die  37 , a first movable die  38 , a second movable die  39 , and a driving gear (not shown) that vertically reciprocates the movable dies  38 ,  39 . The first movable die  38  and the second movable die  39  are arranged at one side of the fixed molding die  37 . An opening  40  is defined in the fixed molding die  37  in correspondence with the shape of the weather strip  15 . The opening  40  includes sub-openings for the bases  21 ,  27 ,  31 , the side walls  22 ,  28 ,  32 , the seal lips  23 ,  24 ,  29 ,  30 ,  33 ,  34  and the auxiliary lips  25 ,  35 . A sub-opening  41  is defined in the opening  40  for forming the inner lips  23 ,  29 ,  33 . The sub-opening  41  corresponds to the shape of the inner seal lip  29  of the upper section  18 , which has the largest cross sectional area among the seal lips  23 ,  29 ,  33 . 
     Furthermore, a sub-opening  56  is defined in the opening  40  for forming the outer seal lips  24 ,  30 ,  34 . The distance between the sub-opening  41  and the sub-opening  56  is greater than the distance between the inner seal lip  23 ,  29 ,  33  and the associated outer seal lip  24 ,  30 ,  34  of the finished weather strip  15 . This prevents the inner seal lip  23 ,  29 ,  33  and the associated outer seal lip  24 ,  30 ,  34  from being close to each other immediately after being extruded. 
     The first movable die  38  includes a pair of fixed guide members  43 , a shutter  44  arranged between the guide members  43 , and a shaft  45  connecting the shutter  44  with the driving gear. Each guide member  43  extends vertically in the vicinity of a variable sub-opening  42 , which forms the auxiliary lips  25 ,  35 . The shutter  44  reciprocates between an open position (see FIG. 5) and a closed position (see FIG. 6) while contacting the face of the fixed molding die  37 . The shutter  44  opens the sub-opening  42  when held in the open position and closes the sub-opening  42  when held in the closed position. 
     The second movable die  39  includes a pair of fixed guide members  46 , a shutter  47  arranged between the guide members  46 , and a shaft  48  connecting the shutter  47  with the driving gear. Each guide member  46  extends vertically in the vicinity of an enlarged sub-opening  41  including a variable sub-opening  41   a.  The shutter  47  reciprocates between an open position (see FIG. 6) and a closed position (see FIG. 5) while contacting the face of the fixed molding die  37 . The shutter  47  opens the variable sub-opening  41   a  when held in the open position and closes the variable sub-opening  41   a  when held in the closed position. 
     The one piece weather strip  15  is formed by extruding rubber material, which is supplied by an extruder (not shown), continuously through the opening  40  of the fixed molding die  37 . Furthermore, each movable die  38 ,  39  reciprocates between its open position and its closed position to vary the shape of the opening  40 . In this manner, the material is extruded through the opening  40  so that the cross sectional areas of the side section  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  each have shapes that are different from one another. 
     If the material is extruded in the order of 1) the rear side section  20 , 2) the rear corner section  19 , 3) the upper section  18 , 4) the front corner section  17 , and 5) the front side section  16 , the weather strip  15  is manufactured specifically in the following manner. 
     To form the rear side section  20 , as shown in FIG. 5, the shutter  44  of the first movable die  38  is held in the open position, while the shutter  47  of the second movable die  39  is held in the closed position. The sub-opening  42  is then open to extrude material through the sub-opening  42 , while the variable sub-opening  41   a  is closed to prevent the material from being extruded through the sub-opening  41   a.  Thus, the material is extruded through the opening  40  to form the rear side section  20 , which includes the outer seal lip  24 , the auxiliary lip  25  projecting from the proximal portion of the outer seal lip  24 , and the inner seal lip  23 , which is not enlarged, as shown in FIG.  3 . 
     The same extrusion is continued to form the rear corner section  19 . However, the shutter  44  of the first movable die  38  gradually moves from the open position to the closed position. Synchronously with the shutter  44 , the shutter  47  of the second movable die  39  moves gradually from the closed position to the open position. In this manner, the sub-opening  42  is gradually closed off. The shutter  44  thus restricts extrusion of the rubber material. This gradually reduces the amount of the rubber material passing through the sub-opening  42 . Furthermore, the sub-opening  41   a  is gradually opened, as the shutter  47  gradually retreats from the sub-opening  41   a.  This gradually increases the amount of rubber material passing through the sub-opening  41   a.  Therefore, the projecting distance of the auxiliary lip  35  decreases as the extrusion progresses, while the inner seal lip  33  becomes larger as the extrusion progresses. The rear corner section  19  is thus integrally extruded with the rear side section  20 . 
     The same extrusion is continued to integrally form the upper section  18 . To form the upper section  18 , the movement of the first movable die  38  and the second movable die  39  in forming the corner section  19  is completed. The shutter  44  of the first movable die  38  is then held in the closed position, while the shutter  47  of the second movable die  39  is held in the open position, as shown in FIG.  6 . In this manner, the sub-opening  42  is closed to restrict flow of the rubber material. Furthermore, the sub-opening  41   a  is open to allow material to pass through the sub-opening  41   a.  The rubber material is thus extruded through the opening  40  to form the upper section  18 . The upper section  18  includes the outer seal lip  30 , which does not have the auxiliary lips  25 ,  35 , and it has the enlarged inner seal lip  29 , as shown in FIG.  4 . 
     The same extrusion continues to form the front corner section  17 . To form the front corner section  17 , the shutter  44  of the first movable die  38  moves gradually from the closed position to the open position. Synchronously with the shutter  44 , the shutter  47  of the second die  39  moves gradually from the open position to the closed position. In this manner, the sub-opening  42  gradually opens, and the shutter  44  retreats from the sub-opening  42 . This gradually increases the amount of the rubber material passing through the sub-opening  42 . Furthermore, the sub-opening  41   a  is gradually closed off, and the shutter  47  thus restricts extrusion of material. This gradually reduces the amount of material passing through the sub-opening  41   a.  Therefore, the projecting distance of the auxiliary lip  35  increases longitudinally, while the inner seal lip  33  becomes smaller. The front corner section  17  is thus extruded integrally with the upper section  18 . 
     The extrusion continues to form the front side section  16 . Furthermore, the front side section  16  is extruded in the same manner as the previously described rear side section  20 . To form the side section  16 , the movement of the first movable die  38  and the second movable die  39  is completed. The initial position of the movable dies  38 ,  39  are thus restored to the position of FIG.  5 . 
     As described, the first embodiment of the weather strip  15  is a single member, although the cross sectional shapes of the side section  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  are different from one another. Furthermore, the side sections  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  are formed integrally in a single extrusion. Therefore, the side sections  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  need not be formed independently and connected to one another afterward. This simplifies the process and the equipment for manufacturing the weather strip  15 . 
     The functions of the weather strip  15 , when attached to the window frame  13  of the vehicle, will hereafter be described. 
     The auxiliary lip  25  of each side section  16 ,  20  increases the pressing force applied by the outer seal lip  24  against the window  14 . This reduces outward deformation of the outer seal lip  24  even though the window  14  moves against the outer seal lip  24  while the outer seal lip  24  is contacting the window  14 . Furthermore, when the window  14  moves to the uppermost position and is completely closed, the clearance  26  has the form of a V-shaped groove between the outer seal lip  24  and the window  14 . Thus, wind may pass through the clearance  26  to cause whistling during traveling of the vehicle. However, the auxiliary lip  25 , which projects from the proximal portion of the outer seal lip  24 , closes the clearance  26  to prevent wind stream from passing through the clearance  26 . This prevents the wind from producing a whistling noise. 
     The inner seal lip  29  of the upper section  18  is larger than the inner seal lip  23  of each side section  16 ,  20 . This increases the rigidity of the inner seal lip  29 . Thus, the distal portion of the inner seal lip  29  is harder to bend. Furthermore, the window  14  moves upward while contacting the inner seal lip  29 , which is enlarged. This positively guides the window  14  to a predetermined position with respect to the upper section  18 . In addition, the auxiliary lips  25 ,  35  are not provided on the outer seal lip  30 . This prevents the window  14  from catching the auxiliary lips  25 ,  35 , when the upper edge of the window  14  enters between the seal lips  29 ,  30  of the upper section  18 . 
     Therefore, the weather strip  15 , which has the same function as that of the conventional weather strip, is extruded by one extruder in a single extrusion. 
     The first embodiment has the following characteristics other than those described above. 
     (a) The conventional weather strip  109  is constructed by at least three independent parts. This may cause a step or a slight gap to be defined between the corner part and the side part  101  or the corner part and the upper part  102 . This makes the appearance of the weather strip  109  less pleasing. Also, the step defined between the seal lips varies the pressing force applied by the seal lips to the window  103 , which varies the sealing performance of the seal lips. To solve these problems, the seal lips need be machined afterward. However, the weather strip  15  according to the present invention is formed as a single member through extrusion molding. The weather strip  15  thus has no step or gap. This improves the appearance of the weather strip  15  and enables uniform sealing performance of the weather strip  15 . This also eliminates the need for the machining and facilitates the manufacturing process. 
     (b) In the conventional weather strip, the side part  101 , and the upper part  102  are extruded separately by extrusion molding. Furthermore, the corner part is molded independently by injection molding. Thus, a lubricating agent such as polyurethane is applied independently to the side part  101 , the upper part  102 , and the corner part. However, in the first embodiment of FIGS. 1 to  6 , the side sections  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  are extruded in one extrusion by a single extruder. Therefore, the lubricating agent can be applied to the seal lips  23 ,  24 ,  29 ,  30 ,  33 ,  34  during the extrusion molding of the weather strip  15 . This further reduces the number of steps for manufacturing the weather strip  15 . 
     (Second embodiment) 
     The second embodiment according to the present invention will now be described with reference to FIGS. 7 to  9 . 
     As shown in FIG. 7, the second embodiment of the weather strip  15  includes an expanded portion  49 . The expanded portion  49  is located on the inner side of the proximal portion of the inner seal lip  29  of the upper section  18  to increase the rigidity of the inner seal lip  29 . 
     As shown in FIGS. 8 and 9, to form the weather strip  15  including the expanded portion  49 , the opening  40  of the fixed molding die  37  is shaped in a different manner from that of the first embodiment. Furthermore, the structure of a second movable die  89  differs from that of the second movable die  39  of the first embodiment. Specifically, the variable sub-opening  41   a  is not defined in the opening  40 . However, a variable sub-opening  50  is defined to form the expanded portion  49 . The second movable die  89  includes a shutter  51  and a shaft  52 , which connects the shutter  51  with the driving gear. The shutter  51  moves longitudinally to project into the sub-opening  50  and backward to retreat from the sub-opening  50 . When the driving gear is actuated, the shutter  51  reciprocates between an open position (see FIG. 9) and a closed position. The shutter  51  opens the sub-opening  50  when held in the open position and closes the sub-opening  50  when held in the closed position. When the shutter  51  is held in the closed position, the distal end of the shutter  51  is flush with the exit side of the fixed molding die  37 . 
     Formation of the expanded portion  49  depends on the position of the shutter  51 , which reciprocates between the open position and the closed position. Specifically, to form each side section  16 ,  20 , the shutter  51  is held in the closed position to close the sub-opening  50 . This forms the side section  16 ,  20  having the cross sectional shapes shown in FIG. 3, which does not include the expanded portion  49 . 
     To form the rear corner section  19 , the shutter  51  gradually moves (retreats) from the closed position toward the open position. The shutter  51  then retreats from the sub-opening  50 . This gradually increases the amount of material passing through the sub-opening  50  as the extrusion progresses. The expanded portion  49 , which becomes gradually larger along the inner seal lip  33  as the extrusion progresses, is thus formed to form the rear corner section  19 . Furthermore, to form the front corner section  17 , the shutter  51  moves from the open position toward the closed position. The expanded portion  49  then becomes gradually smaller along the inner seal lip  33  as the extrusion progresses. The front corner section  17  is thus formed. 
     To form the upper section  18 , the shutter  51  is held in the open position to form the expanded portion  49 . Specifically, when the rubber material passes through the opening  40 , some of the rubber material passes through the sub-opening  50 . The material is therefore shaped as the expanded portion  49 , which is arranged on the inner seal lip  29 . The upper section  18  is thus formed. 
     As described above, although the cross sectional shapes of the side sections  16 ,  20  are different from that of the upper section  18 , the side sections  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  are integrally formed in a single extrusion. The weather strip  15  of the second embodiment is thus constructed by a single piece of material. This facilitates the process and the equipment for manufacturing the weather strip  15  in the same manner as the first embodiment. 
     The functions of the weather strip  15  of the second embodiment, when attached to the door window frame  13  of the vehicle, are the same as that of the first embodiment. In other words, the auxiliary lip  25  of each side section  16 ,  20  reduces outward deformation of the outer seal lip  24  when the window  14  moves upward and downward. The auxiliary lip  25  also suppresses the whistling noise of the wind. Furthermore, the expanded portion  49 , which is arranged on the inner seal lip  29  of the upper section  18 , increases the rigidity of the inner seal lip  29  in comparison with the inner seal lip  23  of the side section  16 ,  20 . The inner seal lip  29  is thus hard to bend. This enables the window  14  to move upward while contacting the inner seal lip  29 , which guides the window  14  to a predetermined position. 
     Therefore, the weather strip  15  of the second embodiment of FIGS. 7 to  9  has a varied cross sectional shape and is formed as a single member by a single extruder. Furthermore, the weather strip  15  of the second embodiment has the same function as that of the conventional weather strip. 
     (Third embodiment) 
     The third embodiment according to the present invention will hereafter be described with reference to FIGS. 10 and 11. 
     In the third embodiment, the inner seal lip  23  of each side section  16 ,  20  and the inner seal lip  29  of the upper section  18  are both enlarged like the inner seal lip  29  of the first embodiment, as indicated by the chain line in FIG.  4 . This enlarges a large portion of each inner seal lip  23 ,  29  extending from the proximal portion of the inner seal lip  23 ,  29  toward the edge of the inner seal lip  23 ,  29 . The inner seal lip  29  of the upper section  18  thus has a high rigidity. Furthermore, as shown in FIG. 10, a notch  53  is defined in a side  23   a  of the inner seal lip  23  that does not contact the window  14 . This improves the flexibility of the distal portion of the inner seal lip  23  of each side section  16 ,  20 . 
     The weather strip  15  having the notched inner seal lip  23  is formed by the movable die shown in FIG.  11 . This die includes a second movable die  99 , the structure of which differs from that of the second movable die  39  of the first embodiment. The second movable die  99  includes a curved shutter  54  and a shaft  55  connecting the shutter  54  with the driving gear (not shown). When the driving gear is actuated, the shutter  54  reciprocates vertically between a projected position (see FIG. 11) and a retreated position while contacting the side of the fixed molding die  37 . The shutter  54  projects into a sub-opening  41  of the opening  40  when held in the projected position, while the shutter  54  retreats from the sub-opening  41  when held in the retreated position. 
     Defining of the notch  53  depends on the position of the shutter  54 , which reciprocates between the projected position and the retreated position. Specifically, to form the front and the rear side sections  16 ,  20 , the shutter  54  is maintained in the projected position. In this state, a portion of the shutter  54  projects into the opening  40 . This restricts flow of the rubber material passing through the opening  40 . The side sections  16 ,  20  having the notch  53  defined in the inner seal lip  23 , as shown in FIG. 10, are thus formed. 
     To form the rear corner section  19 , the shutter  54  moves (downward) gradually from the projected position to the retreated position. The shutter  54  then retreats from the sub-opening  41 . This gradually increases the amount of the rubber material passing through the sub-opening  41 . Therefore, the depth of the notch  53  decreases along the inner seal lip  33  as the extrusion progresses. The corner section  19  is thus formed with a cross sectional shape that varies with time. Furthermore, to form the front corner section  17 , the shutter  54  moves gradually from the retreated position to the projected position. 
     To form the upper section  18 , the shutter  54  is maintained in the retreated position. The rubber material then flows through the entire opening  40 . Thus, the rubber material is extruded through the opening  40  to form the upper section  18 , which does not include the notch  53  on the inner seal lip  29 . 
     As described above, although the cross sections of each side section  16 ,  20  and the upper section  18  have shapes different from each another, the side sections  16 ,  20 , the upper section  18 , and the corner sections  17 ,  19  are formed integrally by means of extrusion molding. The weather strip  15  of the third embodiment is thus formed as a single extruded piece. This facilitates the process and the equipment for manufacturing the weather strip  15  in the same manner as the first embodiment. 
     Functions of the weather strip  15  of the third embodiment when attached to the door window frame  13  of the vehicle are the same as those of the first embodiment. Specifically, although the entire inner seal lip  23  of each side section  16 ,  20  is enlarged, the notch  53  is defined in the inner seal lip  23 . This increases the flexibility of the distal portion of the inner seal lip  23  in comparison with the inner seal lip  29  of the upper section  18 . The pressing force applied by the inner seal lip  23  on the window  14  is thus decreased. This reduces the resistance of the inner seal lip  23  to the sliding of the window  14 . However, the notch  53  is not defined in the inner seal lip  29  of the upper section  18 . This increases the rigidity of the inner seal lip  29  in comparison with the inner seal lip  23  of the side sections  16 ,  20 . The inner seal lip  29  is thus hard to bend. This enables the window  14  to move upward while contacting the inner seal lip  29 , which guides the window  14  to a predetermined position of the upper section  18 . 
     (Fourth embodiment) 
     A fourth embodiment according to the present invention will now be described with reference to FIGS. 12 and 13. 
     Unlike the first to third embodiments, a weather strip  61  of the fourth embodiment is formed partially by means of injection molding. 
     As shown in FIGS. 12 and 13, the weather strip  61  includes, for example, a side section  62 , an upper section  63 , and a corner section  64 , which connects the side section  62  with the upper section  63 . In the same manner as the first embodiment, the side section  62  includes a base  65 , a pair of side walls  67 , an inner seal lip  71 , and an outer seal lip  72 . Furthermore, the upper section  63  includes a base  66 , a pair of side walls  68 , an inner seal lip  73 , and an outer seal lip  74 . In addition, the corner section  64  includes a base  75 , a pair of side walls  76 , an inner seal lip  78 , and an outer seal lip  79 . 
     Except for the cross-hatched portion shown in FIG. 12, the weather strip  61  is formed by means of extrusion molding like the first embodiment. In other words, the entire side section  62 , a portion of the corner section  64  including the lips  78 ,  79  and a portion of each side wall  76 , and the entire upper section  63  are formed integrally to define a single member. This member is manufactured in the following manner. A weather strip shaped identically with the weather strip  15  of the first embodiment is first formed by means of extrusion molding. A portion corresponding to the cross hatched portion of the corner section  64  shown in FIG. 12 is then removed. The cross-hatched portion of the corner section  64  shown in FIG. 12, which includes the base  75  and a portion of each side wall  76 , is then molded independently by injection molding in a metal mold. 
     The functions and advantages of the weather strip  61  of the fourth embodiment will hereafter be described. 
     (a) The fourth embodiment has basically the same advantages as the first to third embodiments. Specifically, although the weather strip  61  is not completely formed by a single extruder, the entire side section  62 , a portion of the corner section  64  including each seal lip  78 ,  79  and a portion of each side wall  76 , and the entire upper section  63  are formed integrally to define a single member. The remaining portion of the corner section  64  is molded in a metal mold after the extrusion. Therefore, the weather strip  61  is constructed by two members. This facilitates the process and the equipment for manufacturing the weather strip  61 , in comparison with the conventional weather strip, which includes four or more parts. 
     (b) Furthermore, the cross-hatched portion of the corner section  64 , which includes the base  75  and a portion of each side wall  76 , is molded independently in a metal mold. The independently molded portion, or reinforcement, restricts the restoring force of the weather strip  61 , in comparison with the weather strip  15  of FIGS. 1 to  11 . This prevents the cross sectional shape of the weather strip  61  from deforming. Therefore, the desired shape of the cross section is maintained. 
     Although several embodiments of the present invention have been described herein, it should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may also be modified as described below. 
     (1) In the fourth embodiment, the base  75  and a portion of each side wall  76  are formed integrally to extend longitudinally along the corner section  64 . Part of the corner section  64  is removed and replaced with a molded reinforcement  75 ,  76 . However, as shown in FIG. 14, a plurality of separate notches may be defined in a portion corresponding to the corner section  64 . Reinforcements corresponding to the notches of the corner section  64  (the cross hatched portion shown in FIG. 14) are molded independently in a metal mold. This structure also has the same advantages (maintaining the cross sectional shape of the weather strip) as the fourth embodiment. 
     (2) Each weather strip  15 ,  61  may be formed of materials other than rubbers such as EDAM. The weather strip  15 ,  61  may be formed of an elastic rubber-like material, such as thermoplastic elastomer (TPE), soft vinyl chloride, and poly blend. 
     (3) Each auxiliary lip  25 ,  35  may be eliminated. 
     (4) In the upper sections  18 ,  63 , the edge of each inner seal lip  29 ,  73  may be joined to the edge of the associated outer seal lip  30 ,  74 . Thus, the entire upper sections  18 ,  63  are each defined as hollow seal portions. 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.