JP2001310755A - Vehicle body front part structure for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body front part structure producing stable effective deceleration based on a subframe when a shock load is applied. SOLUTION: Using inflection points of a deformation mode characteristic of the subframe 30 itself as mounting points, the subframe 30 is installed and supported in a side frame 10 by means of first, second, third, fourth, fifth subframe supporting parts 21, 22, 23, 24, 25 dispersed along the longitudinal direction. In this way, deformation of the subframe 30 is reduced and drag force against the shock load is secured, while the inflection points, in which the subframe 30 is deformed by the shock load, are set between the first and second subframe supporting parts 21, 22, between the second and third subframe supporting parts 22, 23, and between the fourth and fifth subframe supporting parts 24, 25, respectively, and consequently, deceleration can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body front structure, and more particularly, to a vehicle body front structure including a side frame and a subframe coupled to the side frame and supporting front wheels, an engine, and the like.

[0002]

2. Description of the Related Art A front part of a vehicle, for example, an automobile, has a toe board 101 and a floor 102 formed continuously at a lower end of the toe board 101 as schematically shown in a side view of a main part in FIG.
The engine compartment 103 and the passenger compartment 104 are divided by the toeboard 101 from the front of the engine compartment 103.
The side frame 105 extends in the front-rear direction along the lower surface of the floor 102, the subframe 106 supporting the front wheels and the engine and the like extends below the side frame 105, and the rear end of the subframe 106 is firmly The support bracket 107 is supported by the side frame 105 and has a front portion.
Are connected to the side frame 105 via the

As disclosed in Japanese Patent Application Laid-Open No. H11-17045 and schematically shown in FIG. 7, a cross is provided between the front end and the rear end of left and right side members 111 and 112 extending in the vehicle longitudinal direction. A substantially rectangular frame-shaped sub-frame 110 connected by members 113 and 114 is formed, and four corners of the sub-frame 110 are
1, 122 via bolts 125, 126, 127, 128.

When an impact load P equal to or more than a predetermined value is applied from the front of the vehicle, the left rear bolt 127 is broken first, and the rear end of the left side member 111 is moved to the side frame 1.
21 and then the right rear bolt 128 is broken and the rear end of the right side member 112 is
A vehicle body front structure configured to be separated from the vehicle body 2 has been proposed.

[0005]

According to the vehicle body structure shown in FIG. 6, when an impact load P of a predetermined value or more acts on the front end of the subframe 106 from the front, the rear end is firmly connected. As shown by a two-dot chain line 106a in FIG. 6, the intermediate portion of the sub-frame 106 may be buckled and deformed so as to protrude downward, and when the sub-frame 106 opposes the impact load P input from the front, the vehicle When the deceleration of the sub-frame 106 gradually increases and the sub-frame 106 buckles and loses the resistance to the impact load P, the deceleration decreases sharply. There is a concern that it cannot be reduced.

According to the latter Japanese Patent Application Laid-Open No. H11-17045, when the sub-frame 110 receives an impact load P from the front, the rear portions of the left and right side members 111 and 112 have a time difference with the side frames 121 and 122 with a time difference. , The rear ends of the left and right side members 111 and 112 are separated from the side members 121 and 122 at the same time, and one deceleration peak is instantaneously generated. It is dispersed and its peak value is kept low, so that the impact can be reduced and the deceleration can be continuously generated.

However, when receiving the impact load P, the rear ends of the side members 111 and 112 are separated from the side frames 121 and 122 with a time difference, so that the sub frame 110 behaves and the side members 111 and 112 Stable buckling deformation is impeded, and the absorption of impact energy due to the deformation of the subframe 110 becomes unstable, so that an effective reduction in impact cannot be obtained, and the subframe 110
It is difficult to predict in advance the impact energy absorption characteristics due to.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a front vehicle body structure of a vehicle in which a sub-frame can stably absorb shock energy when subjected to an impact load.

[0009]

According to a first aspect of the present invention, there is provided a vehicle body front structure which extends in a vehicle front-rear direction, and a side frame extending below the side frame in a front-rear direction. In the front body structure of a vehicle in which the subframe is mounted and supported by being extended, the subframe includes:
At least three or more mounting points distributed on the sub-frame along the front-rear direction are mounted and supported on the side frame.

According to the first aspect of the present invention, since the sub-frame is mounted and supported on the side frame at mounting points distributed along the front-rear direction, an impact load acts on the front end of the side frame from the front. At this time, deformation and behavior occurring in the side frames are suppressed, and the drag of the sub-frame against an impact load acting from the front is secured, so that effective deceleration can be obtained.

In addition, a deformation mode characteristic in which a deformed portion, that is, an inflection point, is set between each mounting point due to an excessive impact load is obtained, and the deformation is caused by an increase in the number of deformed portions. As a result, the generated energy is increased, and the resistance to the impact load is increased, thereby providing an effective deceleration.
Further, there is no variation in the deformation of the sub-frame, and it is possible to predict in advance the deformation mode characteristics due to the impact load of the sub-frame, and the design of the sub-frame becomes easy.

According to a second aspect of the present invention, in the front body structure of the vehicle according to the first aspect, at least one of the attachment points is characterized by a change in a deformation mode characteristic of the subframe itself due to an impact load from the front. It is a feature point.

According to the second aspect of the present invention, by supporting the inflection point of the deformation mode characteristic of the sub-frame itself on the side frame as an attachment point, the deformation of the inflection point having a large deformation amount of the sub-frame is suppressed. Claim 1 effectively
The effect is achieved.

According to a third aspect of the present invention, in the vehicle body front structure according to the first or second aspect, the mounting point of the subframe is attached to and supported by the side frame due to the strength of a fixture for attaching the subframe to the side frame. The modification mode characteristic of the sub-frame is adjustable.

According to the third aspect of the invention, by changing the strength of the fixture for attaching the sub-frame to the side frame, the deformation mode characteristics of the sub-frame are changed, and the drag of the sub-frame is adjusted. For example, by reducing the strength of some of the mounting bolts, it is possible to adjust the deformation mode characteristics of the subframe, such as reducing the resistance of the subframe by breaking the mounting bolts when the subframe is deformed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of a front body structure of a vehicle according to the present invention will be described below with reference to FIGS. The arrow F indicates the front of the vehicle and the arrow OUT indicates the side of the vehicle.

FIG. 1 is a perspective view of an essential part showing an outline of a vehicle body frame at a front part of the vehicle body, FIG. 2 is a side view of FIG. 1, FIG. 3 is an operation explanatory view schematically showing FIG. It is a graph explaining a shock absorption effect.

The front part of the vehicle body is divided into an engine room 3 and a vehicle room 4 by a toe board 1 and a floor 2 continuously formed at the lower end of the toe board 1, and a pair of left and right side frames 10 (left side in the traveling direction of the vehicle) (Shown only) extends in the front-rear direction from the front end of the engine room 3 to the front surface of the toe board 1 and the lower surface of the floor 2, and a suspension cross member 20 extending in the vehicle width direction is provided between the left and right side frames 10. Have been.

On the side frame 10, a first sub-frame supporting portion 2 formed by a bracket in order from the front side is provided.
1. A second sub-frame support portion 22, a third sub-frame support portion 23, and a fourth sub-frame support portion 24 formed at the end of the suspension cross member 20 are provided so as to protrude downward. , The third, fourth sub-frame support portions 21, 22, 23, 24 at the lower end thereof, for example, first, second, third, fourth mounting bolts 21a, 22a, 23.
The attachment points of the sub-frame 30 extending in the front-rear direction below the side frame 10 are joined by a and 24a, and the lower arm 2 of the front suspension is joined by the third sub-frame support 23 and the fourth sub-frame support 24.
8 is swingably supported.

The left and right sub-frames 30 are connected by a cross member 38 having a front end extending in the vehicle width direction.
0a, the front inclined range 30B descends as it continuously moves rearward to the rear end of the front range 30A, and the front inclined range 30B continues to the rear end through the bent portion 30b and extends in the front-rear direction. Extended range 30C, a rear inclined range 30D that is connected to the rear end of the extended portion 30C via the bent portion 30c and rises as it moves rearward, and a bent portion 30d.
The rear end range 30E is formed continuously with the rear end of the rear inclined range 30D via the rear end range 30E.
Are connected and supported by mounting bolts 25a, 25b on a fifth sub-frame supporting portion 25 formed in the second direction.

The subframe 30 is determined by the shape of the subframe 30 when an impact load P of a predetermined value or more is applied to the front end from the front with only the rear end fixed. The compression deformation is performed according to the deformation mode characteristic as shown by the two-dot chain line M1. That is, the bent portion 30a,
The stress concentrates on 30b, 30c, 30d, and buckling deformation with the inflection point at the portion is induced, and the rear of the front area 30A is pushed up with the retreat of the front end, so that it is inclined upward and backward. The buckling portion 30a is retracted, the front-side inclined range 30B is erected, and the buckling portion 30b is pushed down to retract while buckling.

With the retraction of the buckling portion 30b, the extension range 30C extending in the front-rear direction is retracted, the buckling portion 30c is pushed rearward, and the rear-side inclined range 30D is erected to raise the buckling portion. The buckling deformation occurs by pushing up 30d.

Therefore, in the deformation mode characteristic M1 of the subframe 30 due to its shape, the bent portion 30a,
The amplitude is large at 30b, 30c, and 30d, which is the so-called abdomen. The bent portions 30a and 30b serving as the abdomen,
By suppressing the amount of deformation of the sub-frames 30c and 30d, the deformation of the sub-frame 30 is suppressed, and the resistance to the impact load P acting on the front end of the sub-frame 30 is effectively increased.

Therefore, the first sub-frame supporting portion 21 for supporting the sub-frame 30 is connected to the front region 3 near the bent portion 30a which is an inflection point of the sub-frame 30 itself.
The third sub-frame support portion 23 and the fourth sub-frame are moved to a position corresponding to the rear end of the front inclined range 30B near the bent portion 30b at a position corresponding to the rear end of the first sub-frame. The support portion 24 is located at a position corresponding to the rear end of the extending portion 30C near the bent portion 30c, and the fifth subframe support portion 25 is positioned at a position corresponding to the front end of the rear end range 30E near the bent portion 30d. Each mounting point is set, and each mounting point is set to the first, second, third, fourth, and fifth mounting bolts 21a, 22a, 23a, 24a, 25a, and 25b, respectively. It is mounted and supported on the lower ends of the fourth and fifth sub-frame support portions 21, 22, 23, 24, 25.

Next, the operation of the vehicle body front structure thus constructed will be described with reference to FIG. 3 which schematically shows FIG.

When the impact load P from the front of the vehicle body acts on the front end of the sub-frame 30 and the front end of the sub-frame 30 moves backward, the sub-frame 30 is moved to the first, second, third, fourth, and fourth positions.
Fifth sub-frame support portions 21, 22, 23, 24, 25
As a result, the sub-frame 30 is restrained from being deformed, and the resistance to the impact load P is secured.

On the other hand, the deformation portion where the sub-frame 30 buckles due to the impact load P equal to or more than the predetermined value, that is, the inflection point is between the first sub-frame support portion 21 and the second sub-frame support portion 22, Between the support 22 and the third sub-frame support 23, the fourth sub-frame support 24 and the fifth
The deformation mode characteristic of the sub-frame 30 is set between the sub-frame support 25 and the sub-frame 30 as schematically shown in FIG. 3 and indicated by a two-dot chain line M2.

Since the sub-frame 30 has a deformation mode characteristic in a state where the sub-frame 30 is mounted and supported on the side frame 10, when an impact load P exceeding a predetermined value acts on the front end of the sub-frame 30 from the front of the vehicle body, the sub-frame 30 The first, second, third, fourth, and fifth sub-frame support portions 21, 22, 23, 24, 25 are attached and supported to the side frame 10 to secure the drag, and as shown in FIG. When the load P is input, the deceleration of the vehicle body gradually increases, and when the deceleration reaches a predetermined value, crushing deformation is caused from the front end of the subframe 30 and the deceleration is controlled to be substantially constant. Inflection point, in other words subframe 3
0, between the first sub-frame support portion 21 and the second sub-frame support portion 22, between the second sub-frame support portion 22 and the third sub-frame support portion 23, between the fourth sub-frame support portion 24 and the fifth Deformation with the sub-frame support portion 25 is started, and an increase in drag, that is, an increase in deceleration, is obtained in accordance with the sum of the energy generated due to the deformation at each inflection point.

Therefore, according to the present embodiment, a plurality of sub-frame supports arranged in the front-rear direction, that is, the first, second, third, fourth and fifth sub-frame supports 21,
The sub-frame 30 is mounted and supported on the side frame 10 by the 22, 23, 24, and 25, thereby suppressing the occurrence of deformation, ensuring the resistance to the impact load P acting on the front end of the sub-frame 30 from the front, and ensuring effective operation. Deceleration is ensured.

On the other hand, a deformed portion, ie, an inflection point, generated in the sub-frame 30 due to the excessive impact load P is located between the first sub-frame support 21 and the second sub-frame support 22, The deformation mode characteristic M2 set between the support part 22 and the third sub-frame support part 23 and between the fourth sub-frame support part 24 and the fifth sub-frame support part 25 is obtained, and the number of deformed parts increases. As a result, the energy generated due to the deformation increases. Therefore, subframe 30
Increases the resistance to the impact load, and provides effective absorption of impact energy, so that deceleration can be continuously generated.

As a result, it is possible to avoid such a problem as shown in FIG. 6 that the deceleration sharply decreases due to the buckling deformation of the intermediate portion of the subframe and a peak value of the deceleration occurs instantaneously. it can. Further, since the rear end of the sub-frame 30 is held by the side frame 10, the behavior of the sub-frame 30 is suppressed, and the deformation of the sub-frame 30 does not vary, and the deformation mode characteristic of the sub-frame 30 due to the impact load is accurately determined in advance. , And the design of the sub-frame 30 is facilitated.

Further, the second sub-frame supporting portion 22, the third
Sub-frame support 23, fourth sub-frame support 24
By appropriately omitting the sub-frame support section such as
The deformation position at the inflection point of the sub-frame 30 is reduced, or the deformation mode characteristic is changed by increasing the number of inflection points by increasing the number of sub-frame supports, thereby adjusting the drag.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. In FIG. 5, detailed description is omitted by giving the same reference numerals to parts corresponding to FIG. 2, but in the present embodiment, the third sub-frame support portion 23 and the fourth sub-frame support portion 24 And fourth mounting bolts 23a,
It is characterized in that the strength of 4a is set low.

In such a vehicle, when an impact load P from the front of the vehicle body acts on the front end of the sub-frame 20, when the front end of the sub-frame 30 moves backward, as in the first embodiment, the sub-frame 30 1, 2nd, 3rd, 4th,
Fifth sub-frame support portions 21, 22, 23, 24, 25
As a result, the deformation is suppressed by being attached to and supported by the side frame 10, so that the resistance to the impact load P is ensured.

On the other hand, as in the first embodiment, the deformed portion of the sub-frame 30 due to the impact load P equal to or greater than the predetermined value, that is, the inflection point, is the same as the first sub-frame support 21 and the second sub-frame support 22. , Between the second sub-frame support portion 22 and the third sub-frame support portion 23, between the fourth sub-frame support portion 24 and the fifth sub-frame support portion 25, and the mounting bolts 23a, 24a When is broken, the support by the third sub-frame support portion 23 and the fourth sub-frame support portion 24 is released, and the deformation mode characteristic indicated by the two-dot chain line M3 is obtained.

Since the sub-frame 30 has such a deformation mode characteristic in a state where the sub-frame 30 is mounted and supported, when an impact load P of a predetermined value or more acts on the front end of the sub-frame 20 from the front of the vehicle body, the sub-frame 30 is moved to the The first, second, third, fourth, and fifth subframe support portions 21, 22, 23,
When the impact load P is inputted as shown in FIG. 4, the deceleration of the vehicle body is gradually increased, and the deceleration is set to a predetermined value. Is reached, the deceleration is controlled to be substantially constant by the crush deformation from the front end of the sub-frame 30.

Thereafter, between the first sub-frame support portion 21 and the second sub-frame support portion 22 of the sub-frame 30, between the second sub-frame support portion 22 and the third sub-frame support portion 23, the fourth Deformation between the sub-frame support portion 24 and the fifth sub-frame support portion 25 is started, and the drag is increased in accordance with the sum of the energy generated due to the deformation at each inflection point to obtain deceleration. When the frame 30 is deformed, the mounting bolts 23a, 24a set to low strength
Is broken, the restraint by the third and fourth sub-frame supports 23 and 24 is released between the second sub-frame support 22 and the fifth sub-frame support 25, and the sub-frame 30 is buckled and deformed. An increase in the drag of the frame 30 is suppressed, and the deceleration is positively suppressed as shown by a dashed line in FIG.

Therefore, in addition to the first embodiment, the deceleration,
That is, the impact load P input to the sub-frame 30 from the front
The resistance of the subframe 30 to the mounting bolts 23a,
It can be set by changing the intensity of 24a.

Similarly, the second sub-frame supporting portion 22
By changing the strength of the mounting bolts 22a for mounting and supporting the sub-frame 30, the deformation mode characteristics of the sub-frame 30 can be changed.

Therefore, according to the present embodiment, the mounting bolts 21a, 22a, 23a, which support the sub-frame 30 on the respective sub-frame support portions 21, 22, 23, 24, 25,
By changing the intensities of 24a, 25a, and 25b, the deformation mode characteristic, that is, the deceleration can be adjusted without changing the subframe 30.

The present invention is not limited to the first and second embodiments, but can be variously modified without departing from the spirit of the invention. For example, in each of the above-described embodiments, the first, second, third, fourth, and fifth subframe support portions 21,
The subframe 30 is mounted and supported on the side frame 10 by the five subframe supports 22, 23, 24, and 25.
The resistance of the sub-frame 30 against the impact load, that is, the deceleration can be changed and adjusted by appropriately increasing or decreasing the support of the sub-frame 30.

[0042]

According to the present invention, when the sub-frame is mounted and supported on the side frame at the mounting points distributed along the front-rear direction, when the impact load acts on the front end of the side frame from the front, Deformation and behavior occurring in the side frames are suppressed, and a resistance to an impact load acting on the sub-frame from the front is secured, so that effective deceleration is secured.

Further, a deformed portion generated in the subframe due to an excessive impact load is set between each mounting point, and the energy generated due to the deformation increases as the number of deformed portions increases.
As the resistance to the impact load increases, effective and effective deceleration can be obtained continuously, and the deformation of the sub-frame is not varied, so that it is easy to preset the deformation mode characteristic of the sub-frame due to the impact load. .

In particular, by supporting the inflection point of the deformation mode characteristic of the subframe itself as an attachment point on the side frame, the deformation of the inflection point having a large deformation amount is suppressed, and more effective subframe characteristics are obtained. Can be secured. Also,
By changing the strength of the fixture for attaching the sub-frame to the side frame, the deformation mode characteristics of the sub-frame in the attached state can be variably adjusted, and an efficient drag of the sub-frame can be obtained.

[Brief description of the drawings]

FIG. 1 is an essential part perspective view showing an outline of a first embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an operation explanatory view schematically showing FIG. 2;

FIG. 4 is a graph illustrating a shock absorbing effect.

FIG. 5 is a side view showing a main part of a second embodiment of the present invention.

FIG. 6 is a side view of a main part of an automobile schematically showing a conventional sub-frame mounting support.

FIG. 7 is a plan view showing a main part of a conventional vehicle body front part.

[Explanation of symbols]

Reference Signs List 10 side frame 20 suspension cross member 21 first subframe support (subframe support) 21a first mounting bolt (fixing tool) 22 second subframe support (subframe support) 22a second mounting bolt (fixing tool) ) 23 third sub-frame support (sub-frame support) 23a third mounting bolt (fixing tool) 24 fourth sub-frame support (sub-frame support) 24a fourth mounting bolt (fixing) 25 fifth sub-frame Support part (sub-frame support part) 25a, 25b Fifth mounting bolt (fixing tool)

Claims (3)

[Claims] 1. A front body structure of a vehicle having a side frame extending in a vehicle front-rear direction and a sub-frame extending below the side frame in a front-rear direction and having a sub-frame mounted thereon. A vehicle body front structure, wherein at least three or more mounting points distributed and arranged on the sub-frame along the front-rear direction are mounted and supported on the side frame. 2. The vehicle body front structure according to claim 1, wherein at least one of the attachment points is an inflection point of a deformation mode characteristic of the subframe itself due to an impact load from the front. . 3. The deformation mode characteristic of the sub-frame mounted and supported on the side frame can be adjusted by the strength of a fixture for mounting the mounting point of the sub-frame on the side frame. The vehicle body front structure described in 1.