Rod stiffener for bumper of car

Abstract

A rod stiffener may include a rod molded by a glass fiber reinforced thermoplastic resin, and brackets connected to both ends of the rod, in which properties of a core part forming a center of the rod and an outer part surrounding the core part are formed to be different from each other, and the properties of the core part and the outer part are differentiated by a mixing amount of glass fiber and polypropylene resin including the glass fiber reinforced thermoplastic resin.

Claims

1. A rod stiffener, comprising: a rod molded by a glass fiber reinforced thermoplastic resin and including a core part and an outer part surrounding an outer circumference of the core part, and brackets connected to both ends of the rod, wherein properties of the core part forming a center of the rod and the outer part surrounding the core part are formed to be different from each other, and the properties of the core part and the outer part are differentiated by a mixing amount of glass fiber and polypropylene resin consisting of the glass fiber reinforced thermoplastic resin, wherein the properties of the core part and the outer part are formed so that the outer part has relatively higher stiffness than the core part.

2. The rod stiffener of claim 1, wherein the mixing amount of the glass fiber and the polypropylene resin are mixed at a weight ratio of 60 to 90:10 to 40 of the glass fiber to the polypropylene resin.

3. The rod stiffener of claim 1, wherein the brackets are integrally molded on the rod.

4. A rod stiffener, comprising: a rod molded by a glass fiber reinforced thermoplastic resin and including a core part and an outer part surrounding an outer circumference of the core part; and brackets connected to both ends of the rod, wherein the glass fiber reinforced thermoplastic resin includes a mixing amount of glass fiber and a mixing amount of a polypropylene resin, wherein properties of the core part forming a center of the rod and the outer part surrounding the core part are formed to be different from each other, and the properties of the core part and the outer part are differentiated by the mixing amount of the glass fiber and the mixing amount of the polypropylene resin, wherein the outer part has a relatively higher stiffness than the core part.

5. The rod stiffener of claim 4, wherein the mixing amount of the glass fiber and the polypropylene resin are mixed at a weight ratio of 60 to 90:10 to 40 of the glass fiber to the polypropylene resin.

6. The rod stiffener of claim 4, wherein the mixing amount of the glass fiber is at least 60 wt% or more.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an illustrative view illustrating an installing example of a rod stiffener for describing the present invention;

(2) FIG. 2A is an illustrative view illustrating a structure of an exemplary rod stiffener according to the present invention

(3) FIG. 2B is a cross-sectional view of the line IIB-IIB as shown in FIG. 2A.

(4) FIG. 3 is a cross-sectional view illustrating a layer structure of the exemplary rod stiffener of the line III-III as shown in FIG. 2B.

(5) FIG. 4, FIG. 5, FIG. 6 and FIG. 7 are graphs illustrating measured examples of properties of the exemplary rod stiffener according to the present invention.

(6) It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

DETAILED DESCRIPTION

(7) 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 the 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.

(8) As shown in FIGS. 2A, 2B and 3, a rod stiffener 200 is mounted on a lower portion of a bumper beam, for example bumper beam 100 (see FIG. 1) in order to satisfy a pedestrian standard.

(9) The above-mentioned rod stiffener 200 includes a rod 210 having a fender bar shape which is arranged in a lateral direction while having a predetermined curvature, and brackets 220 integrally formed at both ends of the rod 210.

(10) In this case, since the brackets 220 are integrally molded on the rod 210 unlike the related art, manufacturing processes may be shortened as compared to the related art.

(11) In addition, the rod 210 is formed by a compact body, wherein a core part 212 is provided to a center and an outer part 214 having a form surrounding the core part 212 is provided.

(12) Here, the core part 212 and the outer part 214 may be configured to have different mechanical properties by using the same material but mixing properties of high stiffness and low stiffness, and the core part 212 may be formed to have relatively lower stiffness than the outer part 214.

(13) More specifically, the rod 210 is formed using the glass fiber reinforced thermoplastic resin (GMT) as a main material and may be configured to enable high stiffness and low stiffness to be mixed as described above by varying a mixing ratio of a polypropylene resin which is mixed in glass fiber to manufacture the rod 210.

(14) In this case, in mixing properties of low stiffness of the core part 212 and high stiffness of the outer part 214, when the glass fiber and the polypropylene resin are mixed, as a mixing amount of the polypropylene resin is increased, flexibility is increased to become low stiffness, and as the mixing amount thereof is decreased, stiffness is increased to become high stiffness.

(15) In this case, since the core 212 and the outer part 214 have a relative relationship of property mixing, there is no need to quantitatively determine both parts and the outer part 214 only needs to have relatively stronger properties than the core part 212.

(16) Therefore, each of the core part 212 and the outer part 214 may be mixed within a weight ratio that a mixing ratio of the glass fiber to polypropylene resin is 60 to 90:10 to 40.

(17) Here, the reason for having the mixing ratio of the glass fiber of at least 60 wt % or more is that it is a minimum requirement to reveal basic characteristic of the glass fiber reinforced thermoplastic resin.

(18) Therefore, as shown in the illustration of FIG. 3, in the case in which the core part 212 is a glass fiber (G/F) of 60% in which the glass fiber of 60 wt % and the polypropylene resin of 40 wt % are mixed, the outer part 214 surrounding the core part 212 is formed of G/F of 70% in which the glass fiber of 70 wt % and the polypropylene resin of 30 wt % are mixed, such that the outer part 214 may be formed to have higher stiffness than the core part 212.

(19) By the configuration as described above, weight may be controlled and cost may also be reduced, accordingly.

(20) Additionally, when a car collides with a pedestrian, since the core part 212 is relatively soft, shock absorption amount is increased, such that pedestrian regulations are properly satisfied.

(21) Particularly, since various aspects of the present invention may produce the core part 212 and the outer part 214 by adjusting a difference between properties of the core part 212 and the outer part 214 to be small or large as much as it is desired within a range of the mixing ratio as described above, usefulness is increased as much as the difference.

(22) In order to check whether or not the rod stiffener 200 satisfies the pedestrian regulations, results obtained by measuring a value of force reaching the rod stiffener according to a position at which the pedestrian collides with the bumper beam are illustrated in each of FIGS. 4, 5, 6 and 7.

(23) In this case, BL is an indication indicating a distance which is spaced apart from a length center of the bumper beam (e.g. as illustrated in FIG. 1), that is, a center toward both ends. For example, 0BL means the center and 480BL means a point spaced apart from the center by 480 mm, which is to describe according to the pedestrian standard.

(24) Further, a specification (Spec.), which is required by the regulations, is tibia acceleration of 150G, bending angle of 15 deg, and shear displacement within 5 mm.

(25) In this case, G, which is a unit of the tibia acceleration, means f/kg.

(26) In order to check whether or not the above-mentioned regulations are satisfied, after a rod stiffener in which the core part 212 of G/F of 60% and the outer part 214 of G/F of 70% are mixed, and a rod stiffener in which all of the core part 212 and the outer part 214 have the same G/F of 70% are respectively mounted on the bumper beam, it was checked whether or not the pedestrian regulations are satisfied according to collisions at 0BL and 480BL, and results thereof are illustrated in FIGS. 4 , 5, 6 and 7.

(27) The test results are provided in Table 1 below.

(28) TABLE-US-00001 TABLE 1 Tibia Bending Shear IMPACT Acceleration Angle Displacement NO Classification POINT (150 G) (15 Deg) (5 mm) 1 G/F 0BL 112.8 4.6 1.1 60% and 70% 480BL 132.4 5.1 1.4 2 G/F 70% 0BL 110.8 4.6 1.1 480BL 130.9 5.1 1.4 When properties are mixed, only G value is increased by about 2 G and shear displacement and angle are not changed

(29) As illustrated in the above Table 1, it is illustrated that a case in which high stiffness and low stiffness are mixed has the tibia acceleration which is increased by about 2G as compared to a case in which high stiffness and low stiffness are not mixed and there are no significant differences. Therefore, it may be appreciated that performance stability is also guaranteed.

(30) According to various embodiments of the present invention, the stiffener provided to satisfy the pedestrian regulations may enable cost reduction and weight lightening as compared to the existing stiffener while simultaneously satisfying both stiffness and flexibility, may increase a degree of freedom of the design, and may adjust physical flexible and an energy absorption rate according thereto.

(31) For convenience in explanation and accurate definition in the appended claims, the terms upper, lower, inner and outer are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

(32) 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.