JP2841988B2 - Front cross member of car body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front cross member of a vehicle body, and more particularly to a front cross member of a vehicle having an engine mounted on a front portion of the vehicle body.

[0002]

2. Description of the Related Art As shown in FIGS. 5 and 6, a front cross member 10 provided at a front portion of a vehicle body is formed in a closed cross section by a front plate 11 and a rear plate 12, and is disposed in a lateral direction of the vehicle body. You. The front end of the center member 14 on which the engine 13 is suspended is connected to the front cross member 10 (see FIG. 58-196228).
No.).

[0003]

As shown in FIG. 5, the two axes which are the main axes of the closed cross section of the front cross member 10 are substantially parallel to the axis I extending in the direction in which the second moment of area is maximized. _1, positioned as the axis I ₂ of the second moment is substantially horizontally extending in the direction having the minimum. As a result, when a load in the front-rear direction of the vehicle body is applied to the front cross member, the front cross member is easily deformed in the front-rear direction.

When a rearward load is applied to a running automobile and a rearward load is applied to the front cross member 10, as shown in FIG.
Is deformed rearward, and the center member 1 is accordingly
Since the engine 13 suspended by the engine 4 moves rearward, the passenger compartment is easily deformed by the engine 13.

[0005] In the above-mentioned publication, a connecting portion having an obliquely downwardly inclined surface is provided at the rear end of the center member so that the center member is pushed backward and downward, thereby suppressing deformation of the passenger compartment by the engine. ing.

An object of the present invention is to make it difficult for the front cross member itself to be deformed in the front-rear direction of the vehicle body, thereby suppressing deformation of the passenger compartment by the engine.

[0007]

SUMMARY OF THE INVENTION The present invention is a front cross member formed in a closed cross section by a front plate and a rear plate and connected to a front end of a center member for suspending an engine. The front plate and the rear plate are formed such that an axis extending in a direction in which the secondary moment of area is minimized among two axes that are main axes of the closed cross section is obliquely downward from front to rear, Thus, when a rearward load greater than a predetermined value is applied to the front cross member, the front cross member deforms obliquely downward toward the rear, and moves the center member and the engine downward.

[0008]

[Functions and effects] When a rearward load exceeding a predetermined value is applied to the front cross member, the front cross member is deformed obliquely downward toward the rear, and the center member is moved so that its tip sinks downward. , Move the engine down. As a result, deformation of the passenger compartment, which can occur when the engine moves rearward, is suppressed.

[0009] The front plate and the rear plate are so arranged that, of the two axes which are the main axes of the closed cross section of the front cross member, the axis extending in the direction in which the secondary moment of area is minimized is obliquely downward from the front to the rear. It is sufficient to form a plate, and it is not necessary to add parts, so that the cost is not increased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A front cross member 20 has a front plate 22 and a rear plate 24 as shown in FIGS.
8 to the front end.

In the embodiment shown in FIG. 2, the front plate 22 has a vertical front surface portion 23a, a flange portion 23b located behind and below the front surface portion 23a, and extends obliquely rearward from the front surface portion 23a and is located upward. Horizontal top part 23c
And a flange portion 23d extending vertically from the upper surface portion 23c, and is formed by rolling a plate material.

In the embodiment shown in FIG. 2, the rear plate 24 has a vertical rear surface 25a, a vertical rear surface 25b located behind and above the rear surface 25a, and a rear surface 25a.
A flange portion 25c positioned forward and downward, a curved portion 25d connecting the two rear surface portions 25a and 25b, and projecting forward, and a flange portion 25e extending from the rear surface portion 25b. It is formed by rolling a plate material.

Front plate 22 and rear plate 24
Means that the flange portion 23b and the flange portion 25e are spot-welded, and the flange portion 23d and the flange portion 25e are further welded.
Are spot-welded to form a closed cross section 30.
As a result of the front plate 22 and the rear plate 24 having the above-described shapes, two axes I which are the main axes of the closed cross section 30 are formed.
₁ and I ₂ are at the positions shown in FIG. 2, and the axis I ₂ extending in the direction in which the second moment of area is minimized is obliquely downward from the front to the rear.

The two axes I ₁ and I ₂ pass through the centroid G of the closed section 30 and are orthogonal to each other. The second moment of area of the closed section 30 with respect to the axis I ₂ is maximized, and the axis I ₁
The second moment of area of the closed cross section 30 is minimized. Therefore, the axis I ₂ becomes the extending direction of the second moment is minimized.

The front cross member 20 is disposed in the lateral direction of the vehicle body, and is welded at its end to a front side member 32 disposed in the front-rear direction of the vehicle body as shown in FIG. A bracket 34 is welded to the central rear portion of the front cross member 20, and the front end of the center member 28 with the engine 26 suspended via a mount 36 known per se is bolted to the bracket 34. The rear end of the center member 28 is bolted to the rear cross member 38. The shape of the center member 28 and the coupling structure of the front end and the rear end thereof may be the same as the conventional one.

As shown in FIG. 3, when a load toward the rear A is applied to the front cross member 20, the front cross member 20 is deformed obliquely downward B downward. as a result,
The center member 28 is deformed such that its front end sinks downward, and the engine 26 moves obliquely downward C as indicated by a virtual line. As a result, deformation of the passenger compartment (not shown) located behind the engine 26 is suppressed.

According to the present invention, in addition to the above, the following effects can be obtained.

Since the vibration frequency of the engine 26 at the time of idling substantially matches the natural frequency of the vehicle body, it may resonate. Then, the center member 28 on which the engine 26 is suspended generates a rotational vibration D about the mounting point 40 at the rear end, as shown in FIG. As a result, the joint between the center member 28 and the front cross member 20 tends to move in the tangential direction E. However,
When the front cross member 20 receives the force, the front cross member 20 tries to move backward and downward, so that they interfere with each other and cancel the vibration. Thus, the vibration level at the time of idling of the engine can be reduced.

The front plate 22 is arranged so that, of the two axes which are the main axes of the closed cross section of the front cross member 20, the axis extending in the direction in which the second moment of area is minimized is obliquely downward from the front to the rear. In order to form the front plate 22 and the rear plate 24, it is most preferable to select the shapes of the front plate 22 and the rear plate 24. However, it is also possible to change the plate thickness or to insert a shim between the flanges while selecting the shape while securing sufficient rigidity in the vertical direction.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of a front cross member of an automobile body according to the present invention, and shows a state where the front cross member is connected to a center member.

FIG. 2 is a longitudinal sectional view of a front cross member of an automobile body according to the present invention.

FIG. 3 is a side view showing a state in which an engine is supported by a front cross member and a center member of an automobile body according to the present invention, and schematically shows the operation.

4 is a side view showing a state in which an engine is supported by a front cross member and a center member of an automobile body according to the present invention, and schematically shows an operation different from that of FIG. 3;

FIG. 5 is a longitudinal sectional view of a conventional front cross member.

FIG. 6 is a side view showing a state in which an engine is supported by a conventional front cross member and a center member, and schematically shows the operation.

[Explanation of symbols]

 Reference Signs List 20 front cross member 22 front plate 24 rear plate 26 engine 28 center member 30 closed cross section

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 25/08 B60K 5/12 B62D 21/00 F16M 7/00

Claims (1)

(57) [Claims] 1. A front cross member formed in a closed cross section by a front plate and a rear plate and coupled to a front end of a center member for suspending an engine, wherein the front plate and the rear plate have the closed cross section. The axis extending in the direction in which the second moment of area is minimized is formed so as to be obliquely downward from the front to the rear of the two axes serving as the main axes of the front cross. A front cross member of an automobile body, wherein the front cross member deforms obliquely downward toward the rear when the member joins the member, and moves the center member and the engine downward.