Belt line weather strip

Abstract: A beltline weather strip accommodated in a door panel for elastically contacting a door glass plate (50) and for sliding the door glass plate (50) comprises a base (31) which is substantially parallel to the door glass plate (50) with a cored bar (40) embedded therein, a solid lip (32) protruding from the upper door glass plate (50) side surface of the base (31), and a hollow lip (33) protruding from the lower door glass plate (50) side surface of the base (31), wherein the upper side of the hollow lip (33) is curved inwardly at the root end portion thereof and outwardly at the tip end portion thereof, forming an S-shaped curved upper side as a whole, and a ratio between the curvature radius Ra of the inwardly curved root end portion of the upper side of the hollow lip (33) and the curvature radius Rb of the outwardly curved tip end portion thereof is set as; Ra : Rb = 1 : 2.5 ∼ 1 : 3.5. As a result, it is possible to provide a beltline weather strip being excellent in slidability to be superior to prior art by 20 ∼ 30 % while being equivalent thereto in lip reaction force.

Description: The present invention relates to a beltline weather strip accommodated in a door panel, the beltline weather strip having high lip reaction force against a door glass plate and being excellent in slidability. Conventionally, as a conventional beltline weather strip accommodated in a door panel for elastically contacting a door glass plate 50 which moves up and down and for sliding the same, a beltline weather strip comprising a base 31 which is substantially parallel to the door glass plate 50 with a cored bar 40 embedded therein, a solid lip 32 protruding from the upper door glass plate side surface of the base 31 and a hollow lip 33 protruding from the lower door glass plate side surface of the base 31 has been employed as shown in Figs. 1 to 4. The reason why the hollow lip 33 is provided is to prevent the rattling of the door glass plate 50 and to improve sealing performance between the door glass plate 50 and the beltline weather strip by increasing lip reaction force U against the door glass plate 50. In each of conventional beltline weather strips shown in Figs. 1 to 3, the upper side of the hollow lip 33 is curved inwardly at the root end P portion thereof and outwardly at the tip end Q portion thereof, forming an S-shaped curved upper side as a whole. The relationship between the curvature radius Ra of the inwardly curved root end P portion and the curvature radius Rb of the outwardly curved tip end Q portion of the upper side of the hollow lip 33 is expressed as follows. That is, Ra = Rb is established and a notch 35 is provided on the inner surface at the root end of the lower side of the hollow lip 33 in the conventional weather strip 3b shown in Fig. 1, Ra : Rb = 5: 2 is established in the conventional weather strip 3c shown in Fig. 2, and Ra : Rb = 1: 2 is established in the conventional weather strip 3d shown in Fig. 3. On the contrary, a conventional weather strip 3e shown in Fig. 4 has a hollow lip 33 the upper side of which is curved outwardly at the root end P portion thereof and inwardly at the tip end Q portion thereof. However, each of the conventional weather strips 3b, 3c, 3d and 3e has a problem that slidability relative to the door glass plate 50 is deteriorated although the reaction force U of the lip relative to the door glass plate 50 is increased. Fig. 5 shows a relationship between the displacement of the door glass plate 50 and the lip reaction force U as well as sliding resistance T in the conventional weather strips. Problems to be solved by the invention are as follows. In each of the conventional weather strips, the lip reaction force U against the door glass plate 50 is increased but the slidability relative to the door glass plate 50 is deteriorated. The document US-A-5 388 371 discloses a beltline weather strip comprising a base which is substantially parallel to said door glass plate with a cored bar embedded therein, a solid lip protruding from an upper door glass plate side surface of said base and a hollow lip protruding from a lower door glass plate side surface of said base, wherein an upper side of said hollow lip is curved inwardly at a root end portion thereof and outwardly at a tip end portion thereof, forming an S-shaped curved upper side as a whole. it is an object of the present invention to provide a beltline weather strip having high lip reaction force and being excellent in slidability. The present invention will be now described with reference to Figs. 6 and 8. A beltline weather strip 3a accommodated in a door panel for elastically contacting a door glass plate 50 and for sliding the same comprises a base 31 which is substantially parallel to the door glass plate 50 with a cored bar 40 embedded therein, a solid lip 32 protruding from the upper door glass plate side surface of the base 31, and a hollow lip 33 protruding from the lower door glass plate side surface of the base 31, wherein the upper side of the hollow lip 33 is curved inwardly at the root end P portion thereof and outwardly at the tip end Q portion thereof, forming an S-shaped curved upper side as a whole, and the ratio between curvature radius Ra of the inwardly curved root end P portion and the curvature radius Rb of the outwardly curved tip end Q portion of the upper side of the hollow lip 33 is set as; Ra : Rb = 1 : 2.5 ∼ 1 : 3.5. Fig. 1 is a cross-sectional view of a beltline weather strip according to a first prior art example; Fig. 2 is a cross-sectional view of a beltline weather strip according to a second prior art example; Fig. 3 is a cross-sectional view of a beltline weather strip according to a third prior art example; Fig. 4 is a cross-sectional view of a beltline weather strip according to a fourth prior art example; Fig. 5 is a graph showing displacement-of-glass-plate-to-lip-reaction-force/sliding-resistance curves of the beltline weather strip according to a prior art ; Fig. 6 is a cross-sectional view of a beltline weather strip according to the present invention; Fig. 7 is a cross-sectional view showing a state where the beltline weather strip elastically contacts a door glass plate according to an embodiment of the present invention; Fig. 8 is a graph for comparing displacement-of-glass-plate-to-lip-reaction-force/sliding-resistance curves of the beltline weather strip of the present invention with those of the prior art; and Fig. 9 is a graph showing displacement-of-glass-plate-to-lip-reaction- force/sliding-resistance curves of the beltline weather strip at the time when the door glass plate is stopped and those during the elevation of the door glass plate according to the present invention. An embodiment of the present invention will be now described with reference to Figs. 6 to 9. Denoted at 50 is a door glass plate which moves up and down, 3a is a beltline weather strip for elastically contacting the door glass plate 50 and for sliding the same, the beltline weather strip being structured as follows. That is, the beltline weather strip comprises a base 31 which is substantially parallel to the door glass plate 50 with a cored bar 40 embedded therein, a solid lip 32 protruding from the upper door glass plate side surface of the base 31 and a hollow lip 33 protruding from the lower door glass plate side surface of the base 31, wherein the upper side of the hollow lip 33 is curved inwardly at the root end P portion thereof and outwardly at the tip end Q portion thereof to form an S-shaped curved upper side as a whole, and the ratio between the curvature radius Ra of the inwardly curved root end P portion and the curvature radius Rb of the outwardly curved tip end Q portion of the upper side of the hollow lip 33 is set as; Ra : Rb = 1 : 2.5 ∼ 1 : 3.5. A conventional beltline weather strip has a problem that when Rb/Ra is less than 2.5, both the lip reaction force and sliding resistance are increased at the initial state of flexure and when Rb/Ra is more than 3.5, both the lip reaction force and sliding resistance are increased since the upper side of the hollow lip 33 contacts the base 31 earlier than that of the prior art when the hollow lip 33 is deformed. However, in the case of the present invention wherein Ra/Rb = 2.5 ∼ 3.5 is established, the inwardly curved root end P portion of the upper side of the hollow lip 33 is pushed by the door glass plate 50 to be bent and deformed at a bending point J which is lower than that of the prior art so that stress concentration is hardly take place. As a result, the lip reaction force U at the time when the door glass plate 50 is stopped is about twice as much as that during the elevation of the door glass plate 50 as shown in Fig. 9, so that sliding resistance is remarkably reduced (by 20 ∼ 30 %) as shown in Fig. 8 while the lip reaction force U is equivalent to that of the conventional beltline weather strip. Besides, the displacement-of-glass-plate-to-lip-reaction-force curve rises gently, which shows the excellent slidability and also preferable tendency relative to the fitting variation of the door glass plate. Owing to the above arrangement of the present invention, slidability is excellent since the sliding resistance is reduced by 20 ∼ 30 % compared with that of the conventional beltline weather strip, while lip reaction force is kept equivalent to the conventional beltline weather strip. The features disclosed in the foregoing description, in the following claims and/or in the accompanying drawings may, both separately and in any combination thereof, be material for realising the invention in diverse forms thereof, provided the invention remains that which is defined by the claims.

Claims: A beltline weather strip accommodated in a door panel for elastically contacting a door glass plate (50) and for sliding said door glass plate (50) comprising: a base (31) which is substantially parallel to said door glass plate (50) with a cored bar (40) embedded therein; a solid lip (32) protruding from an upper door glass plate side surface of said base (31); and a hollow lip (33) protruding from a lower door glass plate side surface of said base (31), wherein an upper side of said hollow lip (33) is curved inwardly at a root end P portion thereof and outwardly at a tip end Q portion thereof, forming an S-shaped curved upper side as a whole, characterized in that a ratio between a curvature radius Ra of the inwardly curved root end P portion and a curvature radius Rb of the outwardly curved tip end Q portion of the upper side of said hollow lip (33) is set as Ra:Rb = 1:2.5 ∼ 1:3.5.

Inventors: ISHIBASHI HIROSHI, NAITO HIDEKI, ISHIBASHI, HIROSHI, NAITO, HIDEKI, Ishibashi, Hiroshi, c/o Nichikawa Rubber Co., Ltd., Naito, Hideki, c/o Nishikawa Rubber Co., Ltd.
Applicants: NISHIKAWA RUBBER CO LTD, NISHIKAWA RUBBER CO., LTD.
Application year: 1996
Main classification: B60J10
IPC codes: B60J10, B60J1