Abstract
Several different cross sections of beam having more than four sides are disclosed that may form a central portion of a beam having end portions that have four sides. The end portions of the beams may be received by frame rails. The central portion of the beam between the frame rails may be formed with more than four sides. The additional sides may be recessed beads or protruding ribs. Beams having arcuate recesses or arcuate ribs may be provided on the central portion of the beam. The end portions of the beams may extend outboard of the frame rails. The ribs or beads on the central portion of the beam may provide equivalent performance to four-sided beams having considerably thicker walls. Weight reduction is achieved because the central portion is made of a thinner material while retaining strength by forming beads or ribs in the central portion.
Claims
1. A frame assembly for a vehicle comprising: a transverse beam including four-sided outboard portions having a wall thickness T.sub.1, and a more than four-sided central portion having a wall thickness T.sub.2 that is thinner than T.sub.1, wherein at least one bead extends inwardly from at least one side of the central portion to increase strength; and spaced frame rails each having a four-sided aperture for receiving one of the outboard portions.
2. The frame assembly of claim 1 wherein at least one bead is formed in each of the sides of the central portion, and wherein the beam has a wall length of L1 of the walls adjacent to the bead, the bead has a base wall having a wall length of L2, and wherein the ratio of L1 to L2 is between 0.66 and 2.0.
3. The frame assembly of claim 1 wherein a pair of continuous welds are provided between the outboard portions and the central portion.
4. The frame assembly of claim 1 wherein the central portion further includes twenty sides that each join two adjacent sides at an angle of between 95 and 125.
5. The frame assembly of claim 1 wherein the at least one bead has a pair of oppositely oriented tapered walls and a base wall.
6. A transverse beam for a vehicle comprising: a central portion having more than four sides; a pair of outboard portions having no more than four sides; wherein the central portion has a wall thickness T.sub.1 and the pair of outboard portions having a wall thickness of T.sub.2 that is thicker than T.sub.1 , wherein the central portion has at least one bead formed in at least one side of the central portion that forms at least one of the walls, and wherein the bead extends inwardly from the side of the beam to increase the crush resistance of the beam; and wherein the vehicle has a pair of spaced frame rails that each define at least one four sided aperture, wherein each of the outboard portions of the beam are received in one of the four sided apertures and secured to the frame rails about the apertures.
7. The beam of claim 6 wherein T.sub.1 is 1.5 mm thick and T.sub.2 is 1.8 mm thick.
8. The beam of claim 6 wherein at least one bead is formed in each of the sides of the central portion, and wherein the beam has a wall length of L.sub.1 of the walls adjacent to the bead, the bead has a base wall having a wall length of L.sub.2, and wherein the ratio of L.sub.1 to L.sub.2 is between 0.66 and 2.0.
9. The beam of claim 6 wherein a pair of continuous welds are provided between the outboard portions and the central portion.
10. The beam of claim 6 wherein the central portion further comprises twenty sides that each join two adjacent sides at an angle of between 95 and 125.
11. The beam of claim 6 wherein each of the outboard portions of the beam extend through a pair of four sided apertures defined in parallel walls of each of the spaced frame rails and outboard of the frame rails, wherein the central portion extends to one of the walls of each of the spaced frame rails.
12. The beam of claim 6 wherein the central portion has at least one bead formed in at least one side of the central portion that forms at least one of the walls, and wherein the bead has a pair of oppositely oriented tapered walls and a base wall.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a cross-sectional view of one embodiment of a 20-sided beam;
(2) FIG. 2 is a cross-sectional view of an 8-sided beam with arcuate protruding ribs;
(3) FIG. 3 is a cross-sectional view of an 8-sided beam with arcuate recessed beads;
(4) FIG. 4 is a cross-sectional view of a 20-sided beam with flat walled recessed beads;
(5) FIG. 5 is a perspective view of a beam having a 20-sided central portion;
(6) FIG. 6 is a perspective view of a tailor welded blank;
(7) FIG. 7 is a perspective view of a tubular beam with a 20-sided central portion;
(8) FIG. 8 is a fragmentary plan view of a beam having a 20-sided central portion connected to a pair of frame rails;
(9) FIG. 9 is a graph of a rocker intrusion from a side pole test;
(10) FIG. 10 is a graph of an upper front door intrusion from a side pole test;
(11) FIG. 11 is a graph of a lower front door intrusion from a side pole test; and
(12) FIG. 12 is a graph comparing crush energy absorption for several beams having a cross section in a central portion corresponding to FIG. 3 with different thicknesses.
DETAILED DESCRIPTION
(13) The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the present invention.
(14) Referring to FIG. 1, a 20-sided, 20-cornered beam made according to one embodiment of the present invention, is illustrated. The sides of the beam 10 have a length of S1-S.sub.20 that each have a thickness of T.sub.1-T.sub.20. The different side lengths, thickness, and angles are tunable parameters that allow the beam to be fine-tuned to control crush strength and bending resistance. These parameters may also be tuned to create preferred crush and bending modes for structures that are not uniform and not straight. The beam 10 includes main corners 12. The main corners 12 have an internal angle indicated by . The internal angle is preferably greater than 90 . The internal angle may be between 95 and 125 as measured from the inside of the main corners 12. Between each of the main corners 12, a flat wall bead 14 is provided to increase the strength of the beam 10.
(15) Referring to FIG. 2, a 12-sided beam 16 is shown that includes eight flat walls 18 with two flat walls 18 being provided on opposite sides of each of the main corners 20. Four protruding arcuate ribs 22 are provided between the two flat walls 18 that are disposed between each of the main corners 20. The ribs 22 are arcuate walls that form four additional sides of the beam 16. The main corners 20 have an internal angle that is greater than 90 and may be within 95 and 125 as measured from inside the main corners 20.
(16) Referring to the embodiments of FIGS. 1 and 2, both provide a tunable parameter to optimize bending performance. The lengths of the sides S.sub.1-S.sub.20, thicknesses T.sub.1-T.sub.20 (Radii of the ribs in FIG. 2) and angles .sub.1-.sub.20 are tunable to control crush or bending performance. The parameters are also tunable to meet packaging space requirements and load requirements for vehicle architectures.
(17) Referring to FIG. 3, another alternative embodiment of the invention is shown that includes a 12-sided beam 26. Eight flat walls 28 are provided on opposite sides of each of the main corners 30. The main corners 30 have an inside angle dimension a of greater than 90 and the inside angle may be between 95 and 125. Arcuate recesses 32 forming four arcuate walls are provided between the two walls 28 between each of the main corners 30. The embodiment of FIG. 3 including arcuate recesses may be preferable for crush load resistance while the 8-sided beam 16, shown in FIG. 2 with protruding arcuate ribs 22, offer improved bending moment resistance.
(18) Referring to FIG. 4, a 20-sided non-traditional cross section beam is generally referred to with reference numeral 36. The beam 36 includes outer walls 38 that generally define the outer periphery of the beam 36 Inner side walls 40 extend between the outer walls 38 and the inner base walls 42. Four main corners 44 are provided between each of the outer walls 38. The internal angle of the main corners 44 is greater than 90 and may be between 95 and 125.
(19) Referring further to FIG. 4, the 20 sides of the 20-sided beam are labeled S.sub.1-S.sub.20 and the length of sides S.sub.1, S.sub.2, S.sub.4, S.sub.5, S.sub.6, S.sub.7, S.sub.9, S.sub.10, S.sub.11, S.sub.12, S.sub.14, S.sub.15, S.sub.16, S.sub.17, S.sub.19 and S.sub.20 are each equal to a length L.sub.0. Sides S.sub.3, S.sub.8, S.sub.13, and S.sub.18 may each equal a length L.sub.1. Applicant has found that the optimal ratio L.sub.1/L.sub.0 is between 0.66 and 2.0.
(20) FIGS. 1 and 2 illustrate examples of beams having outboard beads on all four sides of a four-sided beam. FIGS. 3 and 4 illustrate examples of beams having inboard beads on all four sides. These examples may be modified to provide a beam having inboard beads on two sides with two outboard beads on two sides. Alternatively, two inboard beads may be provided on two opposite sides or two outboard beads may be provided on the approved sides. The above are examples of non-uniform cross section with different tunable parameters.
(21) Referring to FIG. 5, a beam 48 with a 20-sided central portion is illustrated. The beam 48 includes flat wall external ribs 50 that are limited to the central portion 52 of the beam 48. Four-sided end portions 54 are provided on both sides of the central portion 52. The four-sided end portions 54 may have rounded corners 56.
(22) Referring to FIG. 6, a pre-stamped, 3D flexible roll-formed, or discontinuous roll-formed tailor welded blank 60 is shown that may be used to form a tubular beam as described above with reference to FIGS. 1-5. The tailor welded blank 60 includes a central portion 62 that may be of a reduced thickness compared to end portions 64. Butt welds 66 may be provided by laser welding, for example, between the central portion 62 and the end portion 64 as part of the manufacturing process for manufacturing the tailor welded blanks 60. Four beads 68 are shown in the central portion 62 of the tailor welded blank 60. The beads 68 may be recessed beads to provide improved crush resistance performance or may be protruding ribs if the beam is intended to reinforce against bending movements. Weight savings may be achieved with the embodiment of FIG. 6 by providing a thinner central portion 62 that is strengthened by the beads 68. The end portions 64 do not include beads 68 and may be made of a thicker material to provide strength equivalent to the strength of the central portion 62 while limiting the amount of thicker material required in the end portions 64.
(23) Referring to FIG. 7, a tubular beam 70 is shown that is one example of a beam that may be manufactured beginning with the tailor welded blank shown in FIG. 6. The tubular beam 70 has a 20-sided central portion 72 that is reinforced with ribs 74 that extend across the central portion 72. The ribs 74 may be formed, for example, in a hydro-forming process. End portions 76 are provided on opposite ends of the central portion 72. The end portion 76 may be thicker than the material used to form the 20-sided central portion 72. Butt welds 78 are provided between the central portion 72 and the end portions 76 of the tailor welded blank 60 as shown in FIG. 6. A frame rail 80 is shown connected to one end of the tubular beam 70. The frame rail 80 defines an opening 82 that extends through both of the parallel walls of the frame rails 80. The end portions 76 may extend completely through the openings 82 in the frame rails 80 and provide outboard extensions 84. Outboard extensions 84 have been shown to improve the performance of the tubular beam 70, particularly in intrusion tests.
(24) Referring to FIG. 8, a beam 86 is shown that includes a plurality of ribs 88. The beam 86 extends between two frame rails 90 and extends beyond the frame rails 90. Extensions 92 extend from the frame rails 90 and may provide improved intrusion test performance, as previously described with reference to FIG. 7.
(25) FIG. 9 is a rocker intrusion chart generally indicated by reference numeral 94. A baseline rocker intrusion from a side pole test illustrates the performance of the four-corner, 2.2 mm thick beam in a rocker intrusion test. The baseline 96 shows the performance of the four-corner 2.2 mm thick beam over a time period of 150 milliseconds with the distance change indicating an intrusion of 350 mm. A test of a reduced weight tailor welded blank 98 having a 1.5 mm thick central portion and a 1.8 mm thick end portion is shown in FIG. 9 to have nearly identical performance in the rocker intrusion test.
(26) Referring to FIG. 10, a front door upper intrusion chart is generally indicated by reference numeral 100. A baseline rocker intrusion test illustrates the performance of the four-corner, 2.2 mm thick beam in a rocker intrusion test. The baseline 104 shows the performance of the four-corner 2.2 mm thick beam over a time period of 150 milliseconds with the distance change indicating an intrusion of 350 mm. A test of a reduced weight tailor welded blank 102 having a 1.5 mm thick central portion and a 1.8 mm thick end portion is shown in FIG. 9 to have nearly identical performance in the rocker intrusion test.
(27) Referring to FIG. 11, a front door lower intrusion chart generally indicated by reference numeral 106. A baseline rocker intrusion test illustrates the performance of the four-corner, 2.2 mm thick beam in a rocker intrusion test. The baseline 110 shows the performance of the four-corner 2.2 mm thick beam over a time period of 150 milliseconds with the distance change indicating an intrusion of 350 mm. A test of a reduced weight tailor welded blank 108 having a 1.5 mm thick central portion and a 1.8 mm thick end portion is shown in FIG. 9 to have nearly identical performance in the rocker intrusion test.
(28) Referring to FIG. 12, a crush energy chart is identified by reference numeral 112. The crush energy chart provides a comparison of beams made in accordance with the embodiment of FIG. 3. The beams tested were of identical size and shape, but had different thicknesses. In the crush energy chart 112, line 114 illustrates the performance of a 1.5 mm beam indicating that the displacement in response to 20,000 kN.mm was approximately 100 mm. Line 116 illustrates the performance of a 1.2 mm beam which at 20,000 kN.mm was approximately 138 mm. Line 118 illustrates a 1.0 mm beam in the test and indicates that at 20,000 kN.mm resulted in a displacement of approximately 180 mm. Line 120 illustrates the crush energy performance of a 0.9 mm beam which at 20,000 kN.mm, the displacement was approximately 220 mm. Line 122 illustrates that in the same test a beam having a thickness of 0.85 mm provided energy absorption of 20,000 kN.mm with a displacement of approximately 235 mm. Line 124 illustrates the performance of a 0.8 mm tube made according to FIG. 3 illustrates that energy absorption of 20,000 kN.mm results in displacement of 250 mm. The baseline square tube having a thickness of 1.5 mm performance is shown as line 126. Energy absorbed in the amount of 20,000 kN.mm required a displacement of 250 mm.
(29) Thicker beams having the shape shown in FIG. 3 perform better than the 0.8 mm thickness beams. However, as the chart illustrates, as similar performance to the heavier 1.55 mm baseline beam may be obtained from a 0.8 mm thickness beam having the shape shown in FIG. 3. Surprisingly, line 124 is fully equivalent to a much heavier and thicker square tube illustrated by line 126 which has a 1.5 mm thickness.
(30) While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
