The present invention relates to a vehicle door structure having a door frame, and more particularly to a door glass run which is inserted into a channel provided at an inner peripheral portion of a door frame so that the door glass run may guide a door glass during its upward and downward displacement and further may seal a passenger compartment at the time when an upper edge of the door glass is in contact with the inner peripheral portion of the door frame.
Referring to FIG. 1, there is shown a side view of a vehicle door 2 which is equipped with a door frame 10. As shown in FIGS. 8, 9 and 10, the door frame 10 has an inner channel 12 on its inner peripheral edge portion. A door glass run 4 according to a prior art, which is made of rubber, is fitted into the inner channel 12 of the door frame 10. A cross-sectional shape of the door glass run 4, as shown in FIGS. 8 and 9, is formed in substantially a letter "U" shape, and the door glass run 4 comprises a base portion 42 which extends in the lateral direction of the vehicle, an inner lip 44 and an outer lip 46 which are connected with the inner and outer portion of the base portion 42 and which extend in the almost parallel relationship with the longitudinal direction of the vehicle. The inner lip 44 has an inclined tip portion 440. Similarly, the outer lip 46 has an tip portion 460 which is inclined in the almost opposite direction of the tip portion 440. A door glass 6 is fitted in a space defined between the inner and outer inclined tip portions 440 and 460. Further, the door glass 6 contacts the inner and outer tip portions 440 and 460 of the door glass run 4 at its interior and exterior surfaces.
When the door glass 6 is displaced upwardly and downwardly, the front edge 62 of the door glass 6 slides within the door glass run 4, which is provided on a front lower frame 8, and the rear edge 64 of the door glass 6 slides within the door glass run 4 which is provided on a rear portion 14 of the door frame 10, thereby enabling smooth vertical displacement of the door glass 6. When the door glass 6 is upwardly displaced to reach a position indicated by the broken line shown in FIG. 1, an upper edge 66 and an inclined front edge 68 of the door glass 6 are designed to fit into the door glass run 4 which is provided on an upper door frame 16 and an inclined front door frame 18, respectively.
In general, when a vehicle runs at a high speed, the flow speed of air which flows on an exterior surface of a vehicle body increases and this causes the air pressure applied to the exterior surface of the door glass 6 to become less than that applied to the interior surface of the door glass 6. As a result, a door glass is displaced toward the exterior of the vehicle body.
In a vehicle having a door equipped with a door frame, when a door glass is upwardly displaced as the vehicle travels at a high speed, suction pulls the door glass 6 is suctioned toward the exterior of the vehicle body as shown in FIG. 10. The suction is caused by the difference in pressure generated between the exterior of the vehicle body and the passenger compartment.
The door glass run 4 according to the prior art has a space 7 defined between the base portion 42 and the outer lip 46. When a vehicle travels at a high speed, the difference in the air pressure generated between the exterior of the vehicle body and the passenger compartment causes the door glass 6 to be displaced the tip portion 460 of the door glass run 4 bends easily. As a result, the upper edge 66 and the inclined front edge 68 of the door glass 6 are displaced toward the exterior of the vehicle body, thereby preventing the upper edge 66 and the inclined front edge 68 of the door glass 6 from smoothly fitting into the door glass run 4 on the upper door frame 16 and on the inclined front door frame 18. Also, a slide resistance between the door glass 6 and the door glass run 4 increases, because a contact surface formed between the exterior surface of the door glass 6 and the inclined tip portion 460 becomes large.