JP6292173B2 - Method for determining vehicle center pillar structure - Google Patents

Description

  The present invention relates to a vehicle center pillar structure determination method and a vehicle center pillar structure determined based on the determination method.

A center pillar is provided at the center position in the vehicle longitudinal direction on the side surface of the vehicle. As an example, a general vehicle center pillar structure 1 shown in FIG. 2 includes an outer panel 3, an inner panel 5, and a reinforcement 7 set inside the outer panel 3, and includes a roof rail 31 and a rocker 33. And are joined.
Such a vehicle center pillar structure 1 is required to be reduced in weight while improving the strength against bending from the viewpoint of a side collision performance in a collision from the side surface of the vehicle. Many techniques have been proposed and implemented so far in order to achieve weight reduction while ensuring strength improvement and strength against bending.

Patent Document 1 discloses a high-strength center pillar that does not increase the number of reinforcing members by defining the ridge curvature of a specific portion of the outer panel.
Patent Document 2 discloses a center pillar structure in which the inner panel enters the outer panel side of the centroid and has a concave shape in order to ensure strength while reducing the number of components.
Patent Document 3 discloses a center pillar frame structure that has high bending strength and is light by optimizing the shape of the reinforcement in the outer panel.
Patent Document 4 discloses a center pillar structure in which strength is improved by setting a reinforcement installation position installed inside the outer panel as a position straddling the curved protrusion of the outer panel.
Patent Document 5 discloses a center pillar structure in which a steel plate for thickening (fine reinforcement) is fixed to the outside of an outer panel manufactured by hot pressing by brazing.

JP 2011-235781 A JP 2013-91458 A JP 2013-159121 A JP 2008-308133 A JP 2011-88484 A

  Although the center pillar disclosed in Patent Document 1 has increased strength without increasing weight, it is difficult to further reduce the weight of the center pillar.

  According to the center pillar structure disclosed in Patent Document 2, a general inner panel has a substantially flat shape, but has a concave inner panel shape that enters the outer panel side of the centroid. As a result, the line length is increased to about twice the normal length, so that the number of parts can be reduced, but a significant lightening effect cannot be expected.

  According to the frame structure of the center pillar disclosed in Patent Document 3, the weight of the reinforcement is often 20% or more of the center pillar assembly as a whole. Changing the shape of the hinders the weight reduction of the entire center pillar assembly.

  The center pillar structure disclosed in Patent Document 4 does not reduce the number of parts of the entire center pillar assembly, and the effect of reducing the weight is very small.

  The center pillar structure disclosed in Patent Document 5 uses an ultra-high-strength steel plate for the outer panel, and the weight increase is suppressed to a minimum by using a micro reinforcement, but the manufacturing method is significantly different from the conventional one. Therefore, the manufacturing cost increases.

As described above, in any of the above techniques, although high strength can be achieved, it is difficult to reduce the weight, and even if the weight reduction is achieved, there is a problem that the manufacturing cost increases.
In the future, when performance such as strength is improved by tightening various regulations required for automobile vehicles, it is difficult to prevent an increase in weight with the above technology, and against an increase in manufacturing cost Is also disadvantageous.
The steel plate strength means the tensile strength of the steel plate.

  Conventionally, it has been known that the performance can be improved by improving the steel plate strength of each component, but there are many cases where the performance improvement effect is small. Since the improvement in steel sheet strength directly leads to an increase in material cost and manufacturing cost, trial and error is necessary to optimize the balance between component performance and manufacturing cost. It was necessary.

  The present invention has been made to solve the above-described problems, and satisfies the collision safety by improving the bending strength at the time of the vehicle side collision without increasing the manufacturing cost and the development cost. It is an object of the present invention to provide a vehicle center pillar structure determination method capable of achieving weight reduction and a vehicle center pillar structure determined based on the determination method.

  As described above, the center pillar structure for a vehicle can be used in the case of a side collision when the vehicle collides from the side of the vehicle by appropriately determining the steel plate strength and thickness of the outer panel and inner panel, the presence or absence of reinforcement, and the strength of the steel plate. A sufficient bending strength can be secured. On the other hand, even if a high-strength and / or thick steel plate is used for each part such as the outer panel, inner panel, or reinforcement, it hardly contributes to improving the bending strength of the vehicle center pillar structure. In some cases, the manufacturing cost and weight of the center pillar structure for use are increased.

Therefore, the inventor clarified the influence of the material strength of each part such as the outer panel, inner panel, and reinforcement used in the vehicle center pillar structure on the strength performance at the time of a vehicle side collision. As a result, it has been found that depending on the combination of the material strength of each part used in the vehicle center pillar structure, it may not contribute to the improvement of the bending strength of the vehicle center pillar structure.
The present invention has been made based on the above findings, and specifically comprises the following configuration.

(1) a method of determining the vehicle center pillar structure with an outer panel and an inner panel according to the present invention, reinforcements for determining the shape of the reinforcements provided between the outer panel and the inner panel a determining step, and the outer panel selection step of selecting the strength of the steel sheet of the outer panel, wherein a inner panel selection step of selecting the strength of the steel sheet of the inner panel, the reinforcements determining step, a pre-Symbol reinforcements It is a process of determining either a split shape consisting of at least two parts or an integrated shape consisting of one part, and the outer panel selection step is for the outer panel to be 1180 MPa class or more, or 780 MPa or more and less than 1180 MPa class a step of selecting a steel plate, the inner panel selection process, before Symbol phosphorus When it is determined as a split shape in the reinforcement selection process, it is a process of selecting a steel plate of 390 MPa class or more and 590 MPa class or less for the inner panel regardless of the steel plate strength of the outer panel selected in the outer panel selection process. It is what.

(2) A method for determining a vehicle center pillar structure including an outer panel and an inner panel according to the present invention is a method of determining the presence and shape of reinforcement provided between the outer panel and the inner panel. A determination step, an outer panel selection step for selecting a steel plate strength of the outer panel, and an inner panel selection step for selecting a steel plate strength of the inner panel,
The reinforcement determination step is a step of determining the reinforcement in one of a divided shape consisting of at least two parts or an integrated shape consisting of one part, and the outer panel selecting step is a step of determining the outer panel. This is the process of selecting a steel plate of 1180 MPa class or higher or 780 MPa or higher and less than 1180 MPa class for the panel, and the inner panel selection process is selected in the outer panel selection process when it is determined as the integral shape in the reinforcement determination process. If the outer panel is a steel plate of 1180 MPa class or higher, select a steel plate of 780 MPa class or higher for the inner panel, or the outer panel selected in the outer panel selection step is a steel plate of 780 MPa class or higher and lower than 1180 MPa class. If there is, it is a process of selecting a steel plate of 390 MPa class or more and 590 MPa class or less for the inner panel. It is characterized by this.

  A method for determining a center pillar structure for a vehicle including an outer panel and an inner panel according to the present invention includes a reinforcement determining step for determining the presence and shape of a reinforcement provided between the outer panel and the inner panel. And an outer panel selecting step for selecting the steel plate strength of the outer panel, and an inner panel selecting step for selecting the steel plate strength of the inner panel, and the vehicle center pillar structure through these steps. By determining the above, it is possible to obtain a vehicle center pillar structure that achieves weight reduction while improving the bending strength at the time of a vehicle side collision and satisfying the collision safety without increasing the manufacturing cost.

It is explanatory drawing of the determination method of the center pillar structure for vehicles which concerns on this invention. It is an exploded view of the center pillar structure for vehicles concerning the present invention (the 1). FIG. 3 is an exploded view of the center pillar structure for a vehicle according to the present invention (part 2). FIG. 3 is an exploded view of a vehicle center pillar structure according to the present invention (part 3); It is explanatory drawing of the analysis model in the FEM analysis of the center pillar structure for vehicles which simulated the time of the side collision concerning Embodiment 1 of this invention. It is an example of the analysis result of the under punch stroke and bending load in the FEM analysis of the center pillar structure for vehicles which simulated the time of the side collision concerning Embodiment 1 of the present invention. In the vehicle center pillar structure according to Embodiment 1 of the present invention, the reinforcement is divided and the vehicle has a steel plate strength and thickness of the inner panel when the outer panel steel plate strength is 1470 MPa class. It is a graph of the relationship between the weight change rate of a center pillar structure, and a maximum load (the 1). In the vehicle center pillar structure according to Embodiment 1 of the present invention, the reinforcement is divided and the vehicle has a steel plate strength and thickness of the inner panel when the steel plate strength of the outer panel is 780 MPa class. It is a graph of the relationship between the weight change rate of a center pillar structure, and a maximum load (the 2). In the vehicle center pillar structure according to the first embodiment of the present invention, the reinforcement is formed in an integral shape, and the steel plate strength and thickness of the inner panel when the steel strength of the outer panel is 1470 MPa class are changed. It is a graph of the relationship between the weight change rate of a center pillar structure, and a maximum load (the 1). In the vehicle center pillar structure according to the first embodiment of the present invention, the reinforcement is integrated and the vehicle has a steel plate strength and thickness of the inner panel when the steel plate strength of the outer panel is 780 MPa class. It is a graph of the relationship between the weight change rate of a center pillar structure, and a maximum load (the 2). In the vehicle center pillar structure according to Embodiment 1 of the present invention, the relationship between the weight change rate of the vehicle center pillar structure and the maximum load when the presence or absence of reinforcement, the steel plate strength and thickness of the outer panel is changed, It is a graph (the 1). In the vehicle center pillar structure according to Embodiment 1 of the present invention, the relationship between the weight change rate of the vehicle center pillar structure and the maximum load when the presence or absence of reinforcement, the steel plate strength and thickness of the outer panel is changed, It is a graph (the 2).

[Embodiment 1]
Prior to description of a method for determining a vehicle center pillar structure according to an embodiment of the present invention, a vehicle center pillar structure targeted in the present embodiment and a side collision performance evaluation method in the vehicle center pillar structure will be described. explain.

<Vehicle center pillar structure>
The center pillar structure for a vehicle according to the present invention includes an outer panel and an inner panel, and includes an outer panel 3 with a divided reinforcement 7 composed of at least two parts as shown in FIG. The inner panel 5 and the inner panel 5 are joined to each other at the joint surface, and the outer panel 3 and the inner panel 5 are connected to each other by interposing a reinforcement 17 composed of one part as shown in FIG. The vehicle center pillar structure 11 joined to each other at the joining surface, or the vehicle center pillar structure 21 joined to the outer panel 3 and the inner panel 5 at the joining surface without providing reinforcement as shown in FIG. Is targeted. Each of the vehicle center pillar structures is disposed in the vehicle with the upper end joined to the roof rail 31 and the lower end joined to the rocker 33.

<Evaluation of side impact performance in vehicle center pillar structure>
In this embodiment, first, in order to examine the side impact performance related to the bending strength of the vehicle center pillar structure, the maximum load of the vehicle center pillar structure simulating the side impact is calculated by finite element method (FEM) analysis. The maximum load at the time of a side collision in the vehicle center pillar structure was evaluated as the side collision performance. And, by clarifying the influence of the steel plate strength and thickness used for the reinforcement, outer panel and inner panel constituting the center pillar structure for a vehicle on the maximum load at the time of the side collision, the outer panel and the inner panel A suitable steel plate strength was studied.

  FIG. 5 shows an example of an analysis model in FEM analysis of a vehicle center pillar structure that simulates a side collision. By the FEM analysis, the load and under punch stroke in a three-point bending test in which the outer panel 3 of the vehicle center pillar structure is pushed by the under punch are measured, and the maximum value in the range of the under punch stroke of 0 to 100 mm is obtained as the maximum load. It was. As boundary conditions in the FEM analysis, a complete constraint condition was given to the upper end part joined to the roof rail 31, and a constraint condition that allowed free rotation to the lower end part joined to the rocker 33.

  FIG. 6 shows an example of the analysis result of the relationship between the under punch stroke and the bending load obtained by the FEM analysis. The analysis results show that the reinforcement shown in Fig. 2 is divided into 590MPa class and 2.0mm thick steel plate, 1470MPa class and 1.2mm thick steel plate on the outer panel, 590MPa class and 1.0mm thick on the inner panel. It is intended for a vehicle center pillar structure using mm steel plates.

  The bending load increases as the underpunch stroke increases, and the bending load reaches a maximum when the underpunch stroke is about 50 mm. When the under punch stroke is in the range of about 50 mm to 110 mm, the bending load temporarily decreases, but when the under punch stroke is about 110 mm or more, the bending load increases again. Therefore, the maximum load of the center panel structure is 27.9 kN from the maximum value in the range where the under punch stroke is 0 to 100 mm.

  Fig. 7 shows the strength and plate of the inner panel in a vehicle center pillar structure that uses a steel plate with a 590MPa grade and 2.0mm thickness steel plate for reinforcement and a 1470MPa grade and 1.2mm thickness steel plate for the outer panel. The relationship between the weight change rate of the vehicle center pillar structure when the thickness is changed and the maximum load at the time of a side collision is shown. The horizontal axis in FIG. 7 is the weight change rate based on a vehicle center pillar structure using a steel plate with a 590 MPa class and a plate thickness of 1.0 mm for the inner panel.

  When the inner panel is a steel plate of 390 MPa class or higher, the effect of the inner panel steel plate strength on the maximum load is small. On the other hand, when the inner panel was a 270 MPa grade steel plate, the maximum load was lower than when a steel plate having the same thickness of 390 MPa grade or higher was used. This indicates that it is preferable to use a steel plate of 390 MPa class or higher for the inner panel.

  In addition, although the maximum load at the time of a side collision tends to increase due to the increase in the thickness of the inner panel, it increases from the general thickness of 0.6 mm to 1.4 mm (as the weight change rate of the entire center pillar structure for vehicles- It was found that the maximum load was only 0.1 kN, that is, 28.1 kN, an improvement of 0.8% or less compared to the maximum load of 27.9 kN at a plate thickness of 0.6 mm. . This indicates that the steel plate cost increases as the strength of the steel plate increases, so that it is effective to use a steel plate of 590 MPa class or less that is generally used for the inner panel in terms of productivity and manufacturing cost. .

  Based on the above, sufficient side impact performance and weight reduction are achieved in the center pillar structure for vehicles using a reinforcement with a 590MPa class steel plate with a split thickness of 2.0mm and an outer panel with a 1470MPa class steel plate with a thickness of 1.2mm. In order to satisfy, it is preferable to use a steel plate of 390 MPa class or more and 590 MPa class or less for the inner panel.

  Fig. 8 shows the strength and plate of the inner panel in a center pillar structure for a vehicle that uses a 590MPa grade steel plate with a split thickness of 2.0mm for reinforcement and a 780MPa grade with a thickness of 1.2mm for the outer panel. The relationship between the weight change rate of the vehicle center pillar structure when the thickness is changed and the maximum load at the time of a side collision is shown. The horizontal axis in FIG. 8 represents the rate of change in weight based on a vehicle center pillar structure using a steel plate having a 590 MPa class and a plate thickness of 1.0 mm for the inner panel.

The maximum load in the weight-reducible region where the rate of weight change is 0% or less, that is, the bending strength of the center pillar structure for a vehicle, does not change greatly even when the inner panel is changed from a 390 MPa class steel plate to a 1470 MPa class steel plate. Since the steel sheet cost increases as the steel sheet strength increases, the upper limit of the steel panel strength of the inner panel is set to a generally used 590 MPa class.
Therefore, satisfactory side-impact performance and light weight are achieved in the center pillar structure for vehicles that uses 590MPa class, 2.0mm thick steel plate for reinforcement and 780MPa, 1.2mm thick steel plate for outer panel. For this purpose, the inner panel is preferably made of a steel plate of 390 MPa class or more and 590 MPa class or less.

  Figure 9 shows the strength of the inner panel and the strength of the inner panel in a vehicle center pillar structure that uses a 1470 MPa grade steel plate with a reinforcement thickness of 2.3 mm and a 1470 MPa grade steel plate with a thickness of 1.8 mm for the outer panel. The relationship between the weight change rate of the vehicle center pillar structure when the thickness is changed and the maximum load at the time of a side collision is shown. The horizontal axis in FIG. 9 represents the rate of change in weight based on a vehicle center pillar structure using a 440 MPa class steel plate with a thickness of 1.2 mm for the inner panel.

  When the inner panel thickness is equal, the maximum load at the side impact increases when the inner panel steel plate strength increases from 440 MPa class to 780 MPa class, but there is a difference in the maximum load when the inner panel steel plate strength is 780 MPa class or higher. I can't. In addition, the maximum load increases as the plate thickness increases, and when the inner panel is changed to a 780MPa grade steel plate from a common plate thickness of 0.6mm to 1.2mm (as a whole vehicle center pillar structure- The maximum load is about 1.5kN, that is, about 8% improvement over the maximum load of 19.2kN at 0.6mm thickness.

  Therefore, satisfactory side impact performance and light weight are achieved in the center pillar structure for vehicles using a 1470MPa class steel plate with a reinforcement thickness of 2.3mm and a 1470MPa class steel plate with a thickness of 1.8mm for the outer panel. For this purpose, it is preferable to use a steel plate of 780 MPa or higher for the inner panel.

  Fig. 10 shows the strength of the inner panel and the strength of the inner panel in a vehicle center pillar structure that uses a 1470 MPa grade steel plate with a reinforcement thickness of 2.3 mm and a 780 MPa grade steel plate with a thickness of 1.8 mm for the outer panel. The relationship between the weight of the vehicle center pillar structure when the thickness is changed and the maximum load at the time of a side collision is shown. The horizontal axis in FIG. 10 represents the rate of change in weight based on a vehicle center pillar structure using a 440 MPa class steel plate with a thickness of 1.2 mm for the inner panel.

The maximum load in the weight-reducible region where the rate of weight change is 0% or less, that is, the bending strength of the center pillar structure for a vehicle, does not change greatly even when the inner panel is changed from a 390 MPa class steel plate to a 1470 MPa class steel plate. In addition, since the steel plate cost increases when the steel plate strength is improved, the steel plate strength of the inner panel is set to the generally used 590 MPa class as the upper limit.
Therefore, in a vehicle center pillar structure that uses a 1470 MPa class steel plate with a reinforcement shape of 1470 MPa, a plate thickness of 2.3 mm, an outer panel of 780 MPa class, and a steel plate with a thickness of 1.8 mm, the inner panel has a 390 MPa class or higher and a 590 MPa class The following steel plates are preferably used.

  Furthermore, for the center pillar structure for a vehicle (see FIG. 4) without an reinforcement and having an outer panel and an inner panel, the influence of the steel panel strength of the outer panel and the inner panel on the maximum load at the time of a side collision was examined. .

  Fig. 11 shows the weight of the center pillar structure for a vehicle when the presence / absence of reinforcement, the steel plate strength and the thickness of the outer panel are changed in the center pillar structure for a vehicle using a 590 MPa class and a plate thickness of 1.2 mm for the inner panel. The relationship between the rate of change and the maximum load during a side impact is shown. For comparison, Fig. 11 shows a case where the thickness of the outer panel using a 1470MPa class steel plate is changed in a center pillar structure for a vehicle provided with a reinforcement of a 590MPa class steel plate with a thickness of 2.0mm. The results of the maximum load are also shown. The horizontal axis in Fig. 11 shows the change in weight based on a vehicle center pillar structure using a reinforcement with a 590MPa class steel plate with a thickness of 2.0mm and a outer panel with a 1470MPa class steel plate with a thickness of 1.2mm. Rate.

When a 1180 MPa grade steel plate is used for the outer panel, the thickness of the outer panel is set to 1.4 mm without providing the reinforcement, which is the same as the case where the reinforcement is provided (indicated by ◆ in FIG. 11). The maximum load is about -13% and a light weight reduction effect of about -13% is obtained.
In addition, when using a 1470MPa grade steel plate for the outer panel, the outer panel has a thickness of 1.3mm without providing reinforcement, resulting in a maximum load greater than that provided with the reinforcement. Lightweight effect (about -17%) can be obtained.

  Therefore, even if there is no reinforcement, it is possible to increase the thickness slightly (0.1mm to 0.2mm) by using a steel plate of 1180MPa class or more for the outer panel, effectively reducing the side impact performance. The weight can be reduced.

  Fig. 12 shows the weight of the center pillar structure for a vehicle when the presence or absence of reinforcement and the steel panel strength and thickness of the outer panel are changed in a vehicle center pillar structure using a 440 MPa class and a plate thickness of 1.2 mm for the inner panel. The relationship between the rate of change and the maximum load during a side impact is shown. The horizontal axis in Fig. 12 is the weight based on the center pillar structure for a vehicle using a steel plate of 590MPa class and 2.0mm thickness, and 1470MPa class and 1.8mm thickness of the outer panel. It is the rate of change.

  When 1180 MPa class steel plate is used for the outer panel, even if reinforcement is not provided, the outer panel thickness is set to 2.0 mm, and the reinforcement is provided using 1470 MPa class steel plate for the outer panel. The maximum load is about the same as that of (♦ in FIG. 12), and a lightening effect of about -21% is obtained.

  In addition, when a 1470 MPa grade steel plate is used for the outer panel, the maximum load is about the same as when the reinforcement is provided by setting the thickness of the outer panel to 1.9 mm without providing the reinforcement. At this time, a weight reduction effect with a weight change rate of about -24% can be expected.

  As mentioned above, the reinforcement set inside the outer panel is a vehicle center pillar structure that does not increase the manufacturing cost, satisfies the side impact performance (= bending strength), and can be reduced in weight. In addition, the roof rails and lockers are not integrated but divided, and the outer panel is made of 1180 MPa class or higher ultra-high-strength steel sheet that can realize a significant weight reduction effect. The inner panel is made of high-tensile steel sheet of 390 MPa class or more and 590 MPa class or less. The one used is preferred.

  Alternatively, the reinforcement set on the inner side of the outer panel is an integrated shape from the roof rail to the rocker, and the outer panel uses a super-high-strength steel plate of 1180 MPa class or higher that can realize a significant lightening effect, and the inner panel is 780 MPa. A center pillar structure for a vehicle using a high-strength steel sheet of grade or higher may be used. In this case, by reducing the thickness of the outer panel slightly (0.1 to 0.2 mm), a significant weight reduction can be realized without reducing the side impact performance without setting reinforcement.

<Vehicle center pillar structure determination method>
Based on the knowledge about the influence of the steel plate strength on the maximum load at the time of a side collision in the vehicle center pillar structure described above, the method for determining the vehicle center pillar structure according to the present embodiment has been found.
The vehicle center pillar structure determining method is a vehicle center pillar structure determining method including an outer panel and an inner panel, and, as shown in FIG. 1, between the outer panel and the inner panel. Reinforcement determination step S1 for determining the presence and shape of reinforcement to be provided, outer panel selection step S3 for selecting the steel plate strength of the outer panel, and inner panel selection step S5 for selecting the steel plate strength of the inner panel; It has. Hereinafter, each step will be described.

≪Reinforcement decision process≫
The reinforcement determination step S1 is a step of determining the presence and shape of the reinforcement set between the outer panel and the inner panel.
And if it is determined that there is reinforcement, the divided shape is not a continuous shape from the roof rail to the rocker (see FIG. 2), or one part from the roof rail at the top of the vehicle to the rocker at the bottom. It is determined as one of the integral shapes (see FIG. 3).

≪Outer panel selection process≫
The outer panel selection step S3 is a step of selecting the steel plate strength of the outer panel based on the presence / absence and shape of the reinforcement determined in the reinforcement determination step S1.
When it is determined in the reinforcement determination step S1 that there is no reinforcement, a steel plate of 1180 MPa class or higher is selected as the outer panel.

  On the other hand, if it is determined in the reinforcement determination step S1 that the reinforcement is present, the outer panel is a steel plate of 1180 MPa class or more, or 780 MPa or more and less than 1180 MPa class, regardless of whether the reinforcement is divided or integrated. Is selected.

≪Inner panel selection process≫
The inner panel selection step S5 determines the steel plate strength of the inner panel based on the presence / absence and shape of the reinforcement determined in the reinforcement determination step S1 and the steel plate strength of the outer panel selected in the outer panel selection step S3. It is a process to select.

  In the reinforcement determination step S1, when it is determined that no reinforcement is provided inside the outer panel and no reinforcement is provided, a steel plate of 780 MPa class or higher is selected for the inner panel.

  When the reinforcement is selected in the reinforcement selection step S1 and the divided shape is determined, the outer panel selected in the outer panel selection step S3 is not less than 1180MP class or more than 780MPa class and less than 1180MPa class. Select a steel plate of 390MPa or more and 590MPa or less.

  When the reinforcement is determined in the reinforcement determination step S1 and the integral shape is determined with the reinforcement, if the outer panel selected in the outer panel selection step S3 is 1180 MPa class or more, a steel plate of 780 MPa class or more is used for the inner panel. If the outer panel selected in the outer panel selection step S3 is 780 MPa class or more and less than 1180 MPa class, a steel sheet of 390 MPa class or more and 590 MPa class or less is selected for the inner panel.

  In the center pillar structure for a vehicle determined by the method for determining the center pillar structure for a vehicle according to the present embodiment, the bending strength at the time of a vehicle side collision, that is, while sufficiently ensuring the safety of collision from the side of the vehicle, Weight reduction can be achieved.

[Embodiment 2]
The vehicle center pillar structure according to another embodiment of the present invention is determined based on the vehicle center pillar structure determination method according to the first embodiment, and has the following three aspects. . In addition, the effect obtained by each center pillar structure for vehicles of aspects 1 to 3 is demonstrated in the examples described later.

<Aspect 1>
The vehicle center pillar structure according to the first aspect is a vehicle center pillar structure 1 including an outer panel 3, an inner panel 5, and a reinforcement 7 as shown in FIG. 2, and an upper end portion of the vehicle center pillar structure 1. The roof rail 31 is joined to the rocker 33 at the lower end.
The reinforcement 7 has a divided shape composed of an upper part 7a and a lower part 7b. The outer panel 3 is a steel plate of 1180 MPa class or higher, and the inner panel 5 is a steel plate of 390 MPa class or higher and 590 MPa class or lower.
In FIG. 2, the reinforcement 7 including the two upper parts 7 a and the lower part 7 b is illustrated, but a divided reinforcement including three or more parts may be used.

  The center pillar structure 1 for a vehicle, in which a divided reinforcement 7 as shown in FIG. 2 is set inside the outer panel 3, absorbs collision energy when a collision (side collision) occurs from the side of the vehicle. The hinge part of the vehicle center pillar structure 1 is sometimes folded, and the amount of deformation of the vehicle inside the cabin tends to be large.

  The vehicle center pillar structure 1 according to the first aspect is demonstrated in the examples described later by making the reinforcement 7 into a divided shape and the steel plate strength of each of the outer panel 3 and the inner panel 5 within the above ranges. As described above, the side collision performance is necessary and sufficiently satisfied, and is superior to the conventional vehicle center pillar structure in terms of weight reduction and manufacturing cost.

<Aspect 2>
The vehicle center pillar structure according to Aspect 2 is a vehicle center pillar structure 11 including an outer panel 3, an inner panel 5, and a reinforcement 17 as shown in FIG. The roof rail 31 is joined to the rocker 33 at the lower end.
The reinforcement 17 is an integral shape made of one part, the outer panel 3 is a steel plate of 1180 MPa class or higher, and the inner panel 5 is a steel plate of 780 MPa class or higher.

  The vehicle center pillar structure 11 in which the integral reinforcement 17 as shown in FIG. 3 is set on the inner side of the outer panel 3 is used for the vehicle even in the event of a vehicle side collision for the purpose of ensuring the safety of the occupant. By improving the bending strength of the center pillar structure 11, deformation to the inside of the vehicle cabin at the time of a side collision is suppressed.

  The center pillar structure 11 for a vehicle according to this aspect 2 has a reinforcement 17 as an integral shape, and the steel plate strength of each of the outer panel 3 and the inner panel 5 is selected from the above range. As described above, side collision performance is necessary and sufficiently satisfied, and is superior to the conventional vehicle center pillar structure in terms of both weight reduction and manufacturing cost.

<Aspect 3>
The vehicle center pillar structure according to the aspect 3 is a vehicle center pillar structure 21 including the outer panel 3 and the inner panel 5 as shown in FIG.
Unlike the first aspect or the second aspect, no reinforcement is set inside the outer panel 3, the outer panel 3 is a steel plate of 1180 MPa class or higher, and the inner panel 5 is a steel plate of 780 MPa class or higher.

  The center pillar structure 21 for a vehicle without reinforcement as shown in FIG. 4 can be reduced in weight as much as the reinforcement is omitted, and the outer side in order to satisfy the required side impact performance (= bending strength). Each panel 3 and inner panel 5 is made of high-tensile steel, and as demonstrated in the examples described later, is particularly superior to the conventional vehicle center pillar structure in terms of weight reduction. is there.

A specific experiment was conducted to confirm the operational effects of the present invention, which will be described below.
In this embodiment, in a vehicle center pillar structure including an outer panel and an inner panel formed of a steel plate, the shape of the reinforcement and the side collision when the steel plate strength and thickness of the outer panel and the inner panel are changed. Various performance, weight change rate and production cost were evaluated.

  The reinforcement was made into three conditions: a split shape that does not continue from the roof rail to the rocker (see FIG. 2), an integral shape that continues from the roof rail to the rocker (see FIG. 3), or no reinforcement (see FIG. 4).

  And the steel plate intensity | strength of an outer panel and an inner panel was determined according to the determination method of the center pillar structure for vehicles which concerns on Embodiment 1. FIG.

  As with the first embodiment, the side impact performance, which is an evaluation item, is an FEM analysis of a three-point bending test in which the vehicle center pillar structure for the analysis model shown in FIG. In the three-point bending test, the maximum value of the load in the range where the under punch stroke is 0 to 100 mm was evaluated as the maximum load of the bending strength at the side collision.

  Table 1 shows the evaluation results of the side impact performance, weight change rate, and manufacturing cost when the strength and thickness of the outer panel and the inner panel are changed in the vehicle center pillar structure in which the reinforcement is divided.

In Table 1, the side impact performance is based on the FEM analysis result (16.7kN) of the maximum load at the time of side impact in the center pillar structure for a vehicle of Conventional Example 1 that is adopted for commercially available vehicles. If it was less than the standard, it was evaluated as x.
Similarly, the rate of change in weight and the manufacturing cost are based on the conventional example 1 which is the center pillar structure for vehicles used in commercial vehicles, and the rate of change in weight is the center pillar structure for vehicles of the conventional example 1 as well as the side collision performance. For the weight (8112 g) and manufacturing cost, the material cost in Conventional Example 1 was used as an evaluation standard.

  Invention Example 1 to Invention Example 3 is a case where a steel plate of 1180 MPa class is selected for the outer panel, and a steel sheet of 390 MPa class or more and 590 MPa class or less is selected for the inner panel. Side impact performance, weight change rate and manufacturing cost Was better than the conventional example 1.

  Invention Example 4 omits reinforcement while the steel plate strength of the outer panel and the thickness of the inner panel are the same as those of Invention Example 3, and the side panel performance is the same as that of Example 3 of the outer panel. In this case, the plate thickness was changed, and the weight change rate and the manufacturing cost were better than those of Conventional Example 1. In particular, a significant weight reduction effect (weight change rate -26%) was obtained.

  Invention Example 5 to Invention Example 7 is a case where a steel plate of 1470 MPa class is selected for the outer panel, and a steel sheet of 390 MPa class or more and 590 MPa class or less is selected for the inner panel. Side impact performance, weight change rate and manufacturing cost Was better than the conventional example 1.

  Example 8 of the present invention omits reinforcement while keeping the steel plate strength of the outer panel and the thickness of the inner panel the same as Example 7 of the present invention, and the maximum load at the time of a side collision is about the same as Example 7 of the present invention. This is a case where the thickness of the outer panel is changed, and both the side impact performance and the manufacturing cost are better than those of the conventional example 1. In particular, a significant lightening effect (weight change rate -30%) is obtained. It was.

  Invention Example 9 is a case where a 980 MPa grade steel plate is selected for the outer panel and a 440 MPa grade steel plate is selected for the inner panel, and the thickness of the outer panel is 1180 MPa grade or 1470 MPa grade steel plate (this Although it was larger than Invention Example 1 to Invention Example 8), all of the maximum load, weight change rate and production cost were better than Conventional Example 1.

  In addition, as shown in Invention Example 10 to Invention Example 13, even if the reinforcement steel sheet strength is other than 590 MPa class, the reinforcement within the scope of the present invention is divided, and the outer panel steel sheet strength is When the steel plate strength of the inner panel was 1390 MPa class or higher and the inner panel steel strength was 390 MPa class to 590 MPa class, the side impact performance, weight change rate, and manufacturing cost were good.

  Table 2 shows, as a comparative example, an inner panel selection step of the method for determining a vehicle center pillar structure according to the present invention in a vehicle center pillar structure in which a reinforcement is divided and a 1180 MPa class steel plate or more is used for an outer panel. The evaluation result of the side impact performance, weight change rate, and manufacturing cost in the case where an inner panel having a steel plate strength outside the range selected in (1) is selected is shown. As in Table 1, Conventional Example 1, which is a vehicle center pillar structure used in commercial vehicles, was used as an evaluation criterion.

Comparative Example 1 and Comparative Example 3 are cases where a 270 MPa grade steel plate lower than the selection range (390 MPa grade, 590 MPa grade or less) in the inner panel selection process is used, and the weight change rate and manufacturing cost are good. The crash performance was below the evaluation standard.
Comparative Example 2 and Comparative Example 4 are cases where a steel plate of 1470 MPa class that is higher than the selection range (390 MPa class or more and 590 MPa class or less) in the inner panel selection process is used, and the side impact performance and weight change rate are good. , Manufacturing costs increased more than evaluation criteria.
Comparative Example 5 is a case where the steel sheet strength of the outer panel is 440 MPa class, which is outside the 1180 MPa class which is the scope of the present invention, and the side collision performance is below the evaluation standard.

  Table 3 shows the evaluation results of the side impact performance, weight change rate, and manufacturing cost when the steel plate strength and thickness of the outer panel and the inner panel are changed in the vehicle center pillar structure in which the reinforcement is integrally formed.

The side impact performance is based on the FEM analysis result (20.5kN) of the maximum load at the time of side impact in the center pillar structure for a vehicle of Conventional Example 2 that is adopted for a commercially available car model. If it was less than this reference | standard, it evaluated as x.
Similarly, the rate of change in weight and the manufacturing cost are based on the conventional example 2 which is the center pillar structure for vehicles used in commercial vehicles, and the rate of change in weight is the center pillar structure for vehicles of the conventional example 2 as well as the side collision performance. For the weight (10076 g) and the manufacturing cost, the material cost in Conventional Example 2 was used as an evaluation standard.

  Invention Example 21 to Invention Example 24 is a case where a steel plate of 1180 MPa class is selected for the outer panel, and a steel plate of 780 MPa class or more and 1470 MPa class or less is selected for the inner panel. Was better than the conventional example 2.

  Invention Example 25 is the same as that of Invention Example 24, in which the outer panel and inner panel have the same steel plate strength, the reinforcement is omitted, and the outer panel and inner panel have the same maximum load as Invention Example 24. This is a case where the plate thickness is changed. Both the side impact performance and the manufacturing cost were better than those of Conventional Example 2, and a significant lightening effect (weight change rate: -21%) was obtained.

  Invention Example 26 to Invention Example 29 is a case where a steel plate of 1470 MPa class is selected for the outer panel, and a steel plate of 780 MPa class or more and 1470 MPa class or less is selected for the inner panel. Was better than the conventional example 2.

  Inventive Example 30 is similar to Inventive Example 29 in that the outer panel and inner panel have the same steel plate strength, but the reinforcement is omitted, and the outer panel and the outer panel are arranged so that the maximum load at the time of a side collision is the same as that of Inventive Example 29. This is a case where the thickness of the inner panel is changed. Both the side impact performance and the cost are better than those of Conventional Example 2, and a significant weight reduction effect (weight change rate: -24%) is obtained.

  In addition, as shown in Examples 31 to 33 of the present invention, even if the reinforcement steel sheet strength is other than 1470 MPa class, the reinforcement within the scope of the present invention is integrally formed, and the outer panel steel sheet strength is 1180 MPa class or more. When the steel panel strength of the inner panel was 780 MPa class or higher, the side impact performance, weight change rate, and manufacturing cost were good.

  As a comparative example, Table 4 shows a method for determining the center pillar structure for a vehicle according to the present invention, in which the reinforcement is integrally formed and the center pillar structure for a vehicle (see FIG. 3) uses a steel plate of 780 MPa class or higher for the outer panel. The evaluation results of the side impact performance, weight change rate, and manufacturing cost when used for an inner panel having a steel plate strength outside the selected range are shown. Similarly to Table 3, Conventional Example 2, which is a vehicle center pillar structure employed in commercial vehicles, was used as an evaluation criterion for each evaluation item.

  In Comparative Example 11, when a steel plate of 780 MPa class or more and less than 1180 MPa class is selected for the outer panel, a steel plate of 1470 MPa class higher than the selected range (390 MPa class or more and 590 MPa class or less) is used for the inner panel. Although the performance was good, the manufacturing cost was below the evaluation standard and the weight change rate increased.

  In Comparative Example 12, when a steel plate of 780 MPa class or more and less than 1180 MPa class is selected for the outer panel, a steel plate of 1180 MPa class higher than the selected range (390 MPa class or more and 590 MPa class or less) is used for the inner panel. Performance and manufacturing costs are good, but the rate of weight change has increased.

  In Comparative Example 13, when a steel plate of 1180 MPa class or higher is selected for the outer panel, a steel plate of 590 MPa class lower than the selection range (780 MPa class or higher) of the inner panel is used, and the weight change rate and manufacturing cost are good. However, the side impact performance was below the evaluation standard.

  In Comparative Example 14, the steel sheet strength of the outer panel was 440 MPa class, which was outside the range of 780 MPa class which is the range of the present invention, and the side impact performance was lower than the evaluation standard.

  From the above, based on the determination method for the center pillar structure for a vehicle according to the present invention, the presence / absence and shape of reinforcement are determined, and the steel plate strength of the outer panel and the strength of the inner panel are selected. It was proved that a vehicle center pillar structure satisfying the side impact performance (in this embodiment, the maximum load at the time of side impact) and suppressing the weight change rate and the manufacturing cost can be realized.

1 Vehicle center pillar structure 3 Outer panel 5 Inner panel 7 Reinforcement (divided shape)
7a Upper part 7b Lower part 11 Vehicle center pillar structure 17 Reinforcement (integral shape)
21 Vehicle center pillar structure 31 Roof rail 31a Roof rail part 31b Roof rail part 33 Rocker 33a Rocker part 33b Rocker part

Claims (2)

A vehicle center pillar structure determination method including an outer panel and an inner panel,
The vehicle center pillar structure determining method is:
And reinforcements determination step of determining the shape of the reinforcements provided between the outer panel and the inner panel,
An outer panel selecting step for selecting the steel plate strength of the outer panel;
An inner panel selection step of selecting the steel plate strength of the inner panel,
The reinforcement determination step includes:
A step of determining a pre-Symbol reinforcements in either the form of integral shape made from the split shape or one part of at least two parts,
The outer panel selection process includes
It is a step of selecting a steel plate of 1180 MPa class or more, or 780 MPa or more and less than 1180 MPa class for the outer panel,
The inner panel selection process includes
Before SL when it is determined that the divided shape in reinforcements selection step, a step of selecting a 390MPa or higher class 590MPa class following the steel sheet to the inner panel regardless of the strength of the steel sheet of the outer panel that was selected by the outer panel selection process A method for determining a center pillar structure for a vehicle. A vehicle center pillar structure determination method including an outer panel and an inner panel,
  The vehicle center pillar structure determining method is:
  A reinforcement determination step for determining a shape of reinforcement provided between the outer panel and the inner panel;
  An outer panel selecting step for selecting the steel plate strength of the outer panel;
  An inner panel selection step of selecting the steel plate strength of the inner panel,
  The reinforcement determination step includes:
  Determining the reinforcement to be either a split shape consisting of at least two parts or an integral shape consisting of one part;
  The outer panel selection process includes
  It is a step of selecting a steel plate of 1180 MPa class or more, or 780 MPa or more and less than 1180 MPa class for the outer panel,
The inner panel selection process includes
  When it is determined as an integral shape in the reinforcement determination step,
  If the outer panel selected in the outer panel selection step is a steel plate of 1180 MPa class or higher, select a steel plate of 780 MPa class or higher for the inner panel, or
  If the outer panel selected in the outer panel selection step is a steel plate of 780 MPa class or more and less than 1180 MPa class, the vehicle center is a step of selecting a steel plate of 390 MPa class or more and 590 MPa class or less for the inner panel. How to determine the pillar structure.