JP2021094878A - Torsion beam - Google Patents

Abstract

To provide a torsion beam capable of improving steering performance and riding comfortableness.SOLUTION: A torsion beam 1 includes a top plate 2 extending in a vehicle width direction DW, and two side plates 3, 4 extending in the vehicle width direction DW. An upper end edge 3a of the side plate 3 of a front side is connected to a front end edge 2a of the top plate 2. An upper end edge 4a of the side plate 4 of a rear side is connected to a rear end edge 2b of the top plate 2. When the length of the top plate 2 in a vehicle length direction DL is L1, the length of the top plate 2 from the front end edge 2a of the top plate 2 to the upper end edge 3a of the side plate 3 of the front side in the vehicle length direction DL is L2f, and the length of the top plate 2 from the rear end edge 2b to the upper end edge 4a of the side plate 4 of the rear side in the vehicle length direction DL is L2r, L2f/L1 and L2r/L1 are 0.60 or below. In the side plate 3 of the front side, the length of a lower end part 3b in the vehicle length direction DL is longer than the length of an upper side part 3c in the vehicle length direction DL. In the side plate 4 of the rear side, the length of a lower end part 4b in the vehicle length direction DL is longer than the length of an upper side part 4c in the vehicle length direction DL.SELECTED DRAWING: Figure 3

Description

The present invention relates to a torsion beam attached to a vehicle.

In a front-wheel drive vehicle (eg, an automobile), a torsion beam may be used to suspend the left and right rear wheels. The torsion beam is a long member and is arranged along the width direction of the vehicle (hereinafter, also referred to as "vehicle width direction"). Trailing arms are joined to both ends of the torsion beam in the vehicle width direction. The front end of each trailing arm is attached to the vehicle body. Each trailing arm supports the rear wheels at its respective rear end.

In the conventional design, the torsion beam is required to have high rigidity against bending around an axis along the vehicle height direction (hereinafter, also referred to as “vehicle height direction”). This flexural rigidity is the rigidity with respect to the amplitude of the vehicle in the front-rear direction (hereinafter, also referred to as “vehicle length direction”). Further, the torsion beam is required to have high rigidity against bending around the axis along the vehicle length direction. This flexural rigidity is the rigidity with respect to the amplitude in the vehicle height direction. The reason why such a high bending rigidity is required for the torsion beam is to prevent a change in the distance (that is, tread) between the tires of the rear wheels when the vehicle is running.

Further, the torsion beam is required to have an appropriate torsional rigidity. This is to absorb the relative displacement in the vehicle height direction that occurs between the left and right rear wheels due to the unevenness of the road surface when the vehicle is running.

Examples of the torsion beam having high flexural rigidity and appropriate torsional rigidity are JP-A-2005-029155 (Patent Document 1), JP-A-2013-256142 (Patent Document 2), and JP-A-2013-256260 (Patent Document 1). It is described in Document 3) and Japanese Patent Application Laid-Open No. 2018-058513 (Patent Document 4).

The torsion beam described in Patent Document 1 has a U-shaped or V-shaped cross-sectional profile. The torsion beam comprises two legs and one bow-shaped ridge section connecting the legs. A hollow profile-curved length section is provided at the free end of at least one leg. The length section is the region of the end face, which is joined to the inner surface of the leg or the outer surface thereof.

The torsion beams described in Patent Documents 2 and 3 have a U-shaped open cross-sectional shape. In the torsion beam described in Patent Document 2, a thick portion is formed at the open end edge of the torsion beam. In the torsion beam described in Patent Document 3, the thickness of the torsion beam in the cross section changes in the circumferential direction, and a thick portion is partially formed.

The torsion beam described in Patent Document 4 has a substantially U-shaped open cross-sectional shape that opens to the lower side of the vehicle. In this torsion beam, the lower end portion of the torsion beam on the opening side is bent toward the outside of the vehicle in the front-rear direction of the vehicle. Among the torsion beams, the lower end portion located on the rear side of the vehicle has the highest rigidity.

Japanese Unexamined Patent Publication No. 2005-029155 Japanese Unexamined Patent Publication No. 2013-256142 Japanese Unexamined Patent Publication No. 2013-256260 Japanese Unexamined Patent Publication No. 2018-058513

As described above, in the conventional design, the characteristics of flexural rigidity and torsional rigidity are examined to determine the shape of the torsion beam. However, it is possible that the steerability and riding comfort may be insufficient only by examining the flexural rigidity and the torsional rigidity. This situation is likely to occur when a rolling vehicle rolls.

An object of the present invention is to provide a torsion beam capable of improving steerability and riding comfort while ensuring bending rigidity and torsional rigidity.

The torsion beam according to the embodiment of the present invention is a torsion beam attached to a vehicle. The torsion beam extends in the width direction of the vehicle, a side plate connected to the front end edge of the top plate and extends downward and in the width direction, and a side plate connected to the rear end edge of the top plate and extends downward and in the width direction. With other side plates. The length of the top plate in the front-rear direction of the vehicle is L1, the length in the front-rear direction from the front end edge of the top plate to the upper end edge of the side plate connected to the front end edge is L2f, and the rear end of the top plate. When the length in the front-rear direction from the edge to the upper end edge of the side plate connected to the rear end edge is L2r, L2f / L1 and L2r / L1 are 0.60 or less. In at least one of the two side plates, the length of the lower end portion located below the center of gravity of the torsion beam in the front-rear direction is longer than the length of the other portion in the front-rear direction.

The torsion beam according to the embodiment of the present invention can improve steerability and ride comfort while ensuring bending rigidity and torsional rigidity.

FIG. 1 is a perspective view schematically showing the overall configuration of the torsion beam. FIG. 2 is a schematic diagram showing elements related to the roll. FIG. 3 is a perspective view schematically showing the overall configuration of the torsion beam of the first embodiment. FIG. 4 is a schematic view showing an example of the cross-sectional shape of the torsion beam of the first embodiment. FIG. 5 is a perspective view schematically showing the overall configuration of the torsion beam of the second embodiment. FIG. 6 is a schematic view showing an example of the cross-sectional shape of the torsion beam of the second embodiment. FIG. 7 is a perspective view schematically showing the overall configuration of the torsion beam of the third embodiment. FIG. 8 is a schematic view showing an example of the cross-sectional shape of the torsion beam of the third embodiment. FIG. 9 is a perspective view schematically showing the overall configuration of the torsion beam of the fourth embodiment. FIG. 10 is a schematic view showing an example of the cross-sectional shape of the torsion beam of the fourth embodiment. FIG. 11 is a perspective view schematically showing the overall configuration of the torsion beam of the first modification. FIG. 12 is a schematic view showing the vertical cross-sectional shape of the torsion beam of the first modification. FIG. 13 is a perspective view schematically showing the overall configuration of the torsion beam of the second modification. FIG. 14 is a schematic view showing the vertical cross-sectional shape of the torsion beam of the second modification. FIG. 15 is a schematic view showing the cross-sectional shape of the torsion beam of the modified example 3. FIG. 16 is a schematic view showing the cross-sectional shape of the torsion beam of the modified example 4. FIG. 17 is a diagram showing a cross-sectional shape of the groove shape examined in the first embodiment. FIG. 18 is a diagram showing a V-shaped cross-sectional shape for comparison examined in Example 1. FIG. 19 is a diagram showing a shear center position when the cross-sectional shape is a groove as a result of the first embodiment. FIG. 20 is a diagram showing the flexural rigidity of the vehicle height direction DH when the cross-sectional shape is a groove as a result of the first embodiment. FIG. 21 is a diagram showing the flexural rigidity of the DL in the vehicle length direction when the cross-sectional shape is a groove as a result of the first embodiment. FIG. 22 is a diagram showing the torsional rigidity when the cross-sectional shape is a groove as a result of the first embodiment. FIG. 23 is a diagram showing the shear center position when the cross-sectional shape is V-shaped as a result of the first embodiment. FIG. 24 is a diagram showing the flexural rigidity of the vehicle height direction DH when the cross-sectional shape is V-shaped as a result of the first embodiment. FIG. 25 is a diagram showing the flexural rigidity of the DL in the vehicle length direction when the cross-sectional shape is V-shaped as a result of the first embodiment. FIG. 26 is a diagram showing the torsional rigidity when the cross-sectional shape is V-shaped as a result of the first embodiment. FIG. 27 is a diagram showing a cross-sectional shape of the groove shape examined in the second embodiment. FIG. 28 shows the results of Example 2.

Hereinafter, embodiments of the present invention will be described. In the following description, embodiments of the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values and specific materials may be exemplified, but the present invention is not limited to these examples.

In order to solve the above problems, the present inventor has examined in detail the situation when a roll occurs. As a result, the following findings were obtained.

[Overview of torsion beam]
FIG. 1 is a perspective view schematically showing the overall configuration of the torsion beam 1. In FIG. 1, the left and right rear wheels Wri and Wle are shown by imaginary lines. With reference to FIG. 1, the torsion beam 1 is an elongated member. The torsion beam 1 is arranged along the vehicle width direction DW. From another point of view, the torsion beam 1 extends in the vehicle width direction DW. That is, the longitudinal direction of the torsion beam 1 coincides with the vehicle width direction DW.

In the present specification, when the direction of the torsion beam 1 and the members constituting the torsion beam 1 is referred to, it means the direction in a state where the torsion beam 1 is mounted on a vehicle and arranged in the orientation at the time of use, unless otherwise specified. For example, the vehicle width direction (vehicle width direction) DW corresponds to the longitudinal direction of the torsion beam 1. This vehicle width direction DW coincides with the left-right direction of the vehicle. The vehicle height direction (vehicle height direction) DH corresponds to the vertical direction of the torsion beam 1. The vehicle length direction (front-rear direction of the vehicle) DL corresponds to the front-rear direction of the torsion beam 1.

Trailing arms 10ri and 10le are joined to the torsion beam 1 at both ends of the DW in the vehicle width direction, the right end 1ri and the left end 1le, respectively. Each trailing arm 10ri and 10le is a rigid body and extends substantially in the vehicle length direction DL. The front ends 10ria and 10lea of the trailing arms 10ri and 10le are attached to the vehicle body. As a result, the torsion beam 1 is attached to the vehicle body. The trailing arms 10ri and 10le support the rear wheels Wri and Wle at their respective rear ends 10rib and 10leb. A spring, a shock absorber, a brake device, and the like that constitute the suspension device are also attached to the trailing arms 10ri and 10le.

[Elements related to roles]
FIG. 2 is a schematic diagram showing elements related to the roll. FIG. 2 shows a torsion beam 1, left and right trailing arms 10ri and 10le, and left and right rear wheels Wri and Wle.

When the vehicle is cornering, the vehicle body receives centrifugal force and the tires (rear wheels Wri, Wle) receive lateral force from the road surface. Rolls are generated by the moments associated with these centrifugal forces and lateral forces. The roll is the rotation of the vehicle body around the axis in the vehicle length direction, and appears as the inclination of the vehicle body to the left and right with respect to the road surface. The center of rotation of the roll is called the roll center Rc.

If the roll is excessively large, the occupant may feel uncomfortable or the steering may become unstable. On the other hand, when the roll is excessively small, the feeling of acceleration and the feeling of deceleration become poor. Therefore, there is an appropriate amount in the roll. The geometry of the suspension allows some control over the degree of roll. Therefore, it is better to have a high degree of freedom in suspension design so that the roll can be set to an appropriate amount.

The roll is the inclination of the vehicle body around the roll center Rc with respect to the road surface. Therefore, the roll is affected by the left-right inclination of the rear wheels Wri and Wle with respect to the road surface and the left-right inclination of the rear wheels Wri and Wle with respect to the vehicle body. Here, the rotation centers of the inclinations of the rear wheels Wri and Wle with respect to the road surface are the ground contact points Tri and Tle of the rear wheels Wri and Wle. The rotation centers of the inclinations of the rear wheels Wri and Wle with respect to the vehicle body are the instantaneous rotation centers Cri and Cle.

The instantaneous rotation centers Cri and Cle are determined by the attachment points Pri and Ple of the torsion beam 1 to the vehicle body and the shear center position Sc of the torsion beam 1. The attachment points Pri and Pl correspond to the positions of the front ends 10ria and 10lea of the trailing arms 10ri and 10le.

Here, the instantaneous rotation center Cri on the right side is defined as follows. A virtual straight line l1ri connecting the attachment point Pl on the left side of the torsion beam 1 and the shear center position Sc of the torsion beam 1 is drawn. A virtual surface A that includes the left and right rear wheels Wri and Wle's grounding points Tri and Tle and is perpendicular to the road surface is drawn. The intersection of the extension line of the straight line l1ri and the surface A is the instantaneous rotation center Cri on the right side. Similarly to this, the instantaneous rotation center Cl on the left side is determined. Specifically, a virtual straight line l1le connecting the attachment point Pri on the right side of the torsion beam 1 and the shear center position Sc of the torsion beam 1 is drawn. The intersection of the extension line of the straight line l1le and the surface A is the instantaneous rotation center Cl on the left side.

Then, the roll center Rc is defined as follows. Draw a virtual straight line l2ri connecting the instantaneous rotation center Cri on the right side and the grounding point Tle of the rear wheel Wle on the left side. Similarly, a virtual straight line l2le connecting the instantaneous rotation center Cl on the left side and the grounding point Tri on the rear wheel Wri on the right side is drawn. The intersection of the straight line l2ri and the straight line l2le is the roll center Rc.

Therefore, the position of the roll center Rc depends on the shear center position Sc of the torsion beam 1. As the shear center position Sc of the torsion beam 1 becomes higher, the instantaneous rotation centers Cri and Cl become higher accordingly. As a result, the position of the roll center Rc is also raised.

The position of the center of gravity G of the vehicle body is higher than the position of the roll center Rc. Therefore, the higher the position of the roll center Rc, the shorter the distance H between the roll center Rc and the center of gravity G of the vehicle body. This distance H is called a roll moment arm. The shorter the roll moment arm H, the smaller the roll angle.

From the above, it can be said that if the shear center position Sc of the torsion beam 1 can be freely controlled, the roll angle can be set to an appropriate amount. In particular, if the roll angle is small, steerability and ride quality are improved. Therefore, as a characteristic of the torsion beam 1, it is desirable that the shear center position Sc is high so that the roll moment arm H is short. The shear center means a point at which a moment due to shear stress does not occur when a long member such as a beam is bent and deformed. The shear center is determined by the cross-sectional shape of the member.

Based on the above findings, the present inventor has examined in detail the cross-sectional shape of the torsion beam composed of plates. As a result, if the cross-sectional shape of the torsion beam is an open cross section that opens downward in the vehicle height direction and the volume (corresponding to the mass) of the region below the center of gravity of the torsion beam is increased, the torsion beam is sheared. It turned out that the center position was high. In particular, it was found that the shear center position increased more significantly in the case of the groove-shaped (U-shaped) cross-sectional shape than in the conventional U-shaped and V-shaped cross-sectional shapes. It was also found that the characteristics (flexural rigidity and torsional rigidity) required for the torsion beam can be secured even with such a unique cross-sectional shape.

The present invention has been completed based on the above findings.

The torsion beam according to the embodiment of the present invention is a torsion beam attached to a vehicle. The torsion beam extends in the width direction of the vehicle, a side plate connected to the front end edge of the top plate and extends downward and in the width direction, and a side plate connected to the rear end edge of the top plate and extends downward and in the width direction. With other side plates. The length of the top plate in the front-rear direction of the vehicle is L1, the length in the front-rear direction from the front end edge of the top plate to the upper end edge of the side plate connected to the front end edge is L2f, and the rear end of the top plate. When the length in the front-rear direction from the edge to the upper end edge of the side plate connected to the rear end edge is L2r, L2f / L1 and L2r / L1 are 0.60 or less. In at least one of the two side plates, the length of the lower end portion located below the center of gravity of the torsion beam in the front-rear direction is longer than the length of the other portion in the front-rear direction (first configuration).

According to the torsion beam of the first configuration, the two side plates face each other, and the cross-sectional shape of the torsion beam is a groove-shaped open cross section that opens downward in the vehicle height direction. Moreover, the volume of the region below the center of gravity of the torsion beam is increased. As a result, the shear center position of the torsion beam is high. Therefore, steerability and ride quality can be improved. In addition, flexural rigidity and torsional rigidity can be ensured.

In the first configuration, the upper edge of the side plate may be directly connected to the front edge of the top plate. The upper end edge of the side plate may be indirectly connected to the front end edge of the top plate. In the latter case, the side plate is connected to the top plate via another plate material. In this case, the other plate material forms a corner connecting the side plate and the top plate. The cross-sectional shape of the corner plate may be an arc shape or a linear shape. Such a connection form of the side plate to the front end edge of the top plate is also applied to the connection form of the side plate to the rear end edge of the top plate.

The lower limit of L2f / L1 and L2r / L1 is not particularly limited and may be 0 (zero). When L2f / L1 is 0, the upper end edge of the side plate is directly connected to the front end edge of the top plate. In this case, the above corner plate does not exist between the upper end edge of the side plate and the front end edge of the top plate. Similarly, when L2r / L1 is 0, the upper end edge of the side plate is directly connected to the rear end edge of the top plate. In this case, the above corner plate does not exist between the upper end edge of the side plate and the rear end edge of the top plate.

L2f / L1 and L2r / L1 are not particularly limited as long as they are 0.60 or less. From the viewpoint of effectively increasing the shear center position of the torsion beam, the upper limit of L2f / L1 and L2r / L1 is preferably 0.50, more preferably 0.40. When L2f / L1 and L2r / L1 exceed 0.60, the cross-sectional shape of the torsion beam approaches the conventional U-shape.

In a typical example, the top plate is flat. However, the top plate includes not only a strictly flat one but also a slightly undulating one.

The connection form, arrangement, shape, etc. of the side plate with respect to the front end edge of the top plate may be the same symmetry as the connection form, arrangement, shape, etc. of the side plate with respect to the rear end edge of the top plate, or may be asymmetrical differently. There may be.

In both side plates of the two side plates, it is preferable that the length of the lower end portion in the front-rear direction is longer than the length of the other portion in the front-rear direction. This is because the shear center position of the torsion beam can be effectively raised.

However, the length of the lower end portion of one of the two side plates in the front-rear direction is longer than the length of the other portion in the front-rear direction, and the thickness of the other side plate is constant over the entire area. It may be just a board of. For example, in the side plate connected to the front end edge of the top plate, the length of the lower end portion in the front-rear direction is longer than the length of the other portion in the front-rear direction, and the side plate connected to the rear end edge of the top plate is , It may be a simple plate having a constant plate thickness over the entire area. In this case, the shear center position of the torsion beam is closer to the front of the vehicle, and as a result, the roll center can be raised.

In the first configuration, in a typical example, the lower end portion of the one side plate has a tubular shape extending in the width direction (second configuration). In the case of the second configuration, the volume of the region below the center of gravity of the torsion beam is increased by the cylindrical lower end portion. The cross-sectional shape of the lower end of the cylinder is not particularly limited. For example, the cross-sectional shape thereof may be a polygon (eg, a triangle, a quadrangle, or a pentagon), or may be a circle or an ellipse.

In another typical example in the first configuration, the plate thickness of the lower end portion of the one side plate is thicker than the plate thickness of the other portion (third configuration). In the case of the third configuration, the volume of the region below the center of gravity of the torsion beam is increased by the lower end portion where the plate thickness is increased.

In the first configuration, when the torsion beam is viewed in a cross section, the lower end portion of the one side plate may have a waveform that alternately projects inward and outward. Further, when the torsion beam is viewed in a cross section, the lower end portion of the one side plate may be L-shaped so that the tip thereof protrudes inward or outward, or protrudes both inward and outward. It may be T-shaped. In the present specification, the inside means a direction approaching the other side plate different from the side plate, and the outside means a direction away from the other side plate different from the side plate. From another point of view, the inside means the inside side of the space surrounded by the top plate and the two side plates, and the outside means the outside side of the space. Even in these cases, the volume of the region below the center of gravity of the torsion beam is increased.

In the first to third configurations, the two side plates facing each other may be inclined so as to move away from the top plate and widen the distance from each other. From another point of view, the side plates may be inclined outward. From yet another point of view, when the torsion beam is viewed in cross section, the angle formed by the side plate and the top plate may be obtuse.

Further, the side plates may be arranged perpendicular to the top plate. From another point of view, when the torsion beam is viewed in cross section, the angle between the side plate and the top plate may be 90 °.

In the first to third configurations, L2f may be larger than L2r (fourth configuration). In the case of the fourth configuration, the shear center position Sc of the torsion beam 1 is moved toward the front of the vehicle, and as a result, the roll center Rc can be raised.

A specific example of the torsion beam of the present embodiment will be described below with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

[First Embodiment]
FIG. 3 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the first embodiment. FIG. 4 is a schematic view showing an example of the cross-sectional shape of the torsion beam 1 of the first embodiment. With reference to FIG. 3, the torsion beam 1 is an elongated member. The torsion beam 1 is arranged along the vehicle width direction DW. From another point of view, the torsion beam 1 extends in the vehicle width direction DW. That is, the longitudinal direction of the torsion beam 1 coincides with the vehicle width direction DW.

The torsion beam 1 includes a flat top plate 2 and two side plates 3 and 4. The top plate 2 extends in the vehicle width direction DW. Each side plate 3 and 4 extends in the vehicle width direction DW. The side plates 3 and 4 are arranged in front of and behind the top plate 2, respectively. The upper end edge 3a of the front side plate 3 is directly connected to the front end edge 2a of the top plate 2. The upper end edge 4a of the rear side plate 4 is directly connected to the rear end edge 2b of the top plate 2. The length of the DW in the vehicle width direction of the top plate 2, the front side plate 3 and the rear side plate 4 is the same.

With reference to FIG. 4, the front side plate 3 is arranged perpendicular to the top plate 2. The rear side plate 4 is also arranged perpendicular to the top plate 2.

The cross-sectional shape of the torsion beam 1 is an open cross section that opens below the DH in the vehicle height direction. This open cross-sectional shape is a groove shape. In other words, this open cross-sectional shape is not the conventional U-shape or V-shape.

Here, the length of the DL of the top plate 2 in the vehicle length direction is L1. The length of the DL in the vehicle length direction from the front end edge 2a of the top plate 2 to the upper end edge 3a of the front side plate 3 is L2f. The length of the DL in the vehicle length direction from the rear end edge 2b of the top plate 2 to the upper end edge 4a of the rear side plate 4 is L2r. In the case of the first embodiment, the side plates 3 and 4 are directly connected to the top plate 2. Therefore, both L2f and L2r are 0 (zero). That is, both L2f / L1 and L2r / L1 are 0 (zero).

In the present specification, the reference points for calculating L1, L2f and L2r are on the inner surface sides of the top plate 2, the front side plate 3, and the rear side plate 4.

In the torsion beam 1 of the first embodiment, the lower end portion 3b of the front side plate 3 has a tubular shape extending in the vehicle width direction DW. The cross-sectional shape of the tubular lower end 3b is quadrangular. In the front side plate 3, the other portion 3c except the lower end portion 3b is a simple plate. In the present specification, this portion 3c may be referred to as an upper portion 3c.

Similarly, the lower end portion 4b of the rear side plate 4 has a tubular shape extending in the vehicle width direction DW. The cross-sectional shape of the tubular lower end 4b is quadrangular. In the rear side plate 4, the other portion 4c except the lower end portion 4b is a simple plate. In the present specification, this portion 4c may be referred to as an upper portion 4c.

The lower ends 3b and 4b of the side plates 3 and 4 are located below the center of gravity Gv of the torsion beam 1. In the front side plate 3, the length 3bt of the lower end portion 3b in the vehicle length direction DL is longer than the length 3ct of the upper end portion 3c in the vehicle length direction DL. The length 3ct of the upper portion 3c in the vehicle length direction DL can be read as the plate thickness of the upper portion 3c. The plate thickness of the tubular lower end portion 3b is the same as the plate thickness of the upper end portion 3c.

Similarly, in the rear side plate 4, the length 4bt of the lower end portion 4b in the vehicle length direction DL is longer than the length 4ct of the upper end portion 4c in the vehicle length direction DL. The length 4ct of the upper portion 4c in the vehicle length direction DL can be read as the thickness of the upper portion 4c. The plate thickness of the tubular lower end portion 4b is the same as the plate thickness of the upper end portion 4c.

With such a configuration, the volume (mass) of the region below the center of gravity Gv of the torsion beam 1 is increased. As a result, the shear center position Sc of the torsion beam 1 is high. Therefore, steerability and ride quality can be improved. In addition, flexural rigidity and torsional rigidity can be ensured.

The lower end 3b of the front side plate 3 may be tubular, and the rear side plate 4 may be a simple plate having a constant plate thickness over the entire area. On the contrary, the lower end portion 4b of the rear side plate 4 may be tubular, and the front side plate 3 may be a simple plate having a constant plate thickness over the entire area.

[Second Embodiment]
FIG. 5 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the second embodiment. FIG. 6 is a schematic view showing an example of the cross-sectional shape of the torsion beam 1 of the second embodiment. With reference to FIGS. 5 and 6, in the case of the second embodiment, the upper end edge 3a of the front side plate 3 is connected to the front end edge 2a of the top plate 2 via the corner plate 5. The upper end edge 4a of the rear side plate 4 is connected to the rear end edge 2b of the top plate 2 via the corner plate 6. The lengths of the top plate 2, the front side plate 3, the rear side plate 4, and the corner plates 5 and 6 in the vehicle width direction are the same. The cross-sectional shapes of the corner plates 5 and 6 are arcuate.

In the case of the second embodiment, the side plates 3 and 4 are indirectly connected to the top plate 2. That is, each side plate 3 and 4 is connected to the top plate 2 via the corner plates 5 and 6. Due to the presence of the corner plates 5 and 6, both L2f / L1 and L2r / L1 exceed 0 (zero). Further, both L2f / L1 and L2r / L1 are 0.60 or less. The cross-sectional shape of such a torsion beam 1 is also a groove shape.

Similar to the first embodiment, the torsion beam 1 of the second embodiment also has an increased volume in the region below the center of gravity Gv of the torsion beam 1. Therefore, the torsion beam 1 of the second embodiment also has the same effect as that of the first embodiment.

[Third Embodiment]
FIG. 7 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the third embodiment. FIG. 8 is a schematic view showing an example of the cross-sectional shape of the torsion beam 1 of the third embodiment. With reference to FIGS. 7 and 8, in the case of the third embodiment, the cross-sectional shapes of the corner plates 5 and 6 are linear.

In the case of the third embodiment as well, as in the second embodiment, both L2f / L1 and L2r / L1 exceed 0 (zero) and are 0.60 or less. The cross-sectional shape of such a torsion beam 1 is also a groove shape.

Similar to the first embodiment, the torsion beam 1 of the third embodiment also has an increased volume in the region below the center of gravity Gv of the torsion beam 1. Therefore, the torsion beam 1 of the third embodiment also has the same effect as that of the first embodiment.

[Fourth Embodiment]
FIG. 9 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the fourth embodiment. FIG. 10 is a schematic view showing an example of the cross-sectional shape of the torsion beam 1 of the fourth embodiment. The torsion beam 1 of the fourth embodiment is a modification of the torsion beam 1 of the first embodiment.

With reference to FIGS. 9 and 10, in the torsion beam 1 of the fourth embodiment, the lower end portion 3b of the front side plate 3 is a simple plate like the upper portion 3c. However, the plate thickness of the lower end portion 3b is thicker than the plate thickness of the upper end portion 3c. That is, in the front side plate 3, the length 3bt of the lower end portion 3b in the vehicle length direction DL is longer than the length 3ct of the upper end portion 3c in the vehicle length direction DL.

Similarly, the lower end portion 4b of the rear side plate 4 is a simple plate like the upper portion 4c. However, the plate thickness of the lower end portion 4b is thicker than the plate thickness of the upper end portion 4c. That is, in the rear side plate 4, the length 4bt of the lower end portion 4b in the vehicle length direction DL is longer than the length 4ct of the upper end portion 4c in the vehicle length direction DL.

Similar to the first embodiment, the torsion beam 1 of the fourth embodiment also has an increased volume in the region below the center of gravity Gv of the torsion beam 1. Therefore, the torsion beam 1 of the fourth embodiment also has the same effect as that of the first embodiment.

The plate thickness of the lower end portion 3b of the front side plate 3 may be increased, and the plate thickness of the rear side plate 4 may be a simple plate having a constant plate thickness over the entire area. On the contrary, the plate thickness of the lower end portion 4b of the rear side plate 4 may be increased, and the plate thickness of the front side plate 3 may be a simple plate having a constant plate thickness over the entire area.

The form of increasing the plate thickness of the lower end portions 3b and 4b at the side plates 3 and 4 as in the fourth embodiment may be applied to the second and third embodiments. The fourth embodiment for increasing the thickness of the lower end portion 3b of the front side plate 3 is applied, and the first to third embodiments for forming the lower end portion 4b into a tubular shape are applied to the rear side plate 4. May be good. On the contrary, the fourth embodiment of increasing the plate thickness of the lower end portion 4b of the rear side plate 4 is applied, and the lower end portion 3b of the front side plate 3 is formed into a tubular shape from the first to the third. Embodiments may be applied.

Other modifications are shown below.

[Modification 1]
FIG. 11 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the modified example 1. FIG. 12 is a schematic view showing the vertical cross-sectional shape of the torsion beam 1 of the modified example 1. The torsion beam 1 of the modification 1 is, as an example, a modification of the torsion beam 1 of the fourth embodiment.

With reference to FIGS. 11 and 12, the torsion beam 1 of the first modification includes the middle plates 7ri and 7le. The middle plates 7ri and 7le are provided in the vicinity of the right end 1ri and the left end 1le of the torsion beam 1, respectively. The middle plates 7ri and 7le are provided inside the space surrounded by the top plate 2 and the two side plates 3 and 4. When the torsion beam 1 is viewed in a cross section, a closed cross section is formed by the top plate 2, the two side plates 3 and 4, and the middle plates 7ri and 7le. The middle plates 7ri and 7le reinforce only the vicinity of the right end 1ri and the left end 1le of the torsion beam 1.

[Modification 2]
FIG. 13 is a perspective view schematically showing the overall configuration of the torsion beam 1 of the modified example 2. FIG. 14 is a schematic view showing the vertical cross-sectional shape of the torsion beam 1 of the modified example 2. The torsion beam 1 of the modification 2 is, as an example, a modification of the torsion beam 1 of the fourth embodiment.

With reference to FIGS. 13 and 14, the torsion beam 1 of the second modification includes a rod 8. The rod 8 is provided inside the space surrounded by the top plate 2 and the two side plates 3 and 4. The rod 8 extends over the entire longitudinal direction (vehicle width direction DW) of the torsion beam 1. The rod 8 reinforces the entire torsion beam 1.

[Modification 3]
FIG. 15 is a schematic view showing the cross-sectional shape of the torsion beam 1 of the modified example 3. The torsion beam 1 of the modification 3 is, as an example, a modification of the torsion beam 1 of the fourth embodiment.

With reference to FIG. 15, in the torsion beam 1 of the modified example 3, the lower end portion 3b of the front side plate 3 is a simple plate like the upper portion 3c. However, the plate thickness of the lower end portion 3b is thicker than the plate thickness of the upper end portion 3c. On the other hand, the rear side plate 4 is a simple plate having a constant plate thickness over the entire area. That is, the plate thickness of the lower end portion 4b is the same as the plate thickness of the upper end portion 4c. In this case, the shear center position Sc of the torsion beam 1 moves closer to the front of the vehicle, and as a result, the roll center Rc can be raised.

[Modification example 4]
FIG. 16 is a schematic view showing the cross-sectional shape of the torsion beam 1 of the modified example 4. As an example, the torsion beam 1 of the modified example 4 is a combination of the torsion beam 1 of the third embodiment and the torsion beam 1 of the fourth embodiment.

With reference to FIG. 16, in the torsion beam 1 of the modified example 4, the upper end edge 3a of the front side plate 3 is connected to the front end edge 2a of the top plate 2 via the corner plate 5. On the other hand, the upper end edge 4a of the rear side plate 4 is directly connected to the rear end edge 2b of the top plate 2. In the case of the modified example 4, L2f is larger than L2r. In this case, the shear center position Sc of the torsion beam 1 moves closer to the front of the vehicle, and as a result, the roll center Rc can be raised.

Modifications 1 to 4 can be combined with each other.

In Example 1, the effectiveness of the torsion beam having a groove-shaped cross-sectional shape was investigated. FIG. 17 is a diagram showing a cross-sectional shape of the groove shape examined in the first embodiment. FIG. 18 is a diagram showing a V-shaped cross-sectional shape for comparison examined in Example 1. Numerical analysis of the groove-shaped cross-sectional shape shown in FIG. 17 and the V-shaped cross-sectional shape shown in FIG. 18 shows the shear center position Sc, the bending rigidity in the vehicle height direction DH, and the bending rigidity in the vehicle length direction DL. , And the torsional rigidity were investigated. For reference, FIGS. 17 and 18 show the shear center position Sc and the center of gravity Gv of the torsion beam 1 having each cross-sectional shape.

With reference to FIG. 17, the groove-shaped cross-sectional shape was formed by the top plate 2, the two side plates 3 and 4, and the two corner plates 5 and 6. The height from the lower ends of the side plates 3 and 4 to the top plate 2 (the length of the DH in the vehicle height direction) was 80 mm. The distance between the side plates 3 and 4 (the length of the DL in the vehicle length direction) was 80 mm. The cross-sectional shape of the corner plates 5 and 6 was an arc shape, and the radius of curvature thereof was 10 mm. That is, L2f and L2r were 10 mm each. From these dimensional relationships, the height of each side plate 3 and 4 (the length of the DH in the vehicle height direction) was 70 mm. The width of the top plate 2 (the length of the DL in the vehicle length direction) was 60 mm. That is, L1 was 60 mm.

The top plate 2 was evenly divided into three regions along the DL in the vehicle length direction. These regions were designated as the front region (ii), the central region (i), and the rear region (ii) in order from the front. The regions of the corner plates 5 and 6 were designated as corner regions (iii). Each side plate 3 and 4 was evenly divided into three regions along the vehicle height direction DH. These regions were designated as the upper region (iv), the intermediate region (v), and the lower region (vi) in order from the top. At least the lower region (vi) was located below the center of gravity Gv of the torsion beam.

With reference to FIG. 18, the V-shaped cross-sectional shape was formed by the ridge plate 101 and the two inclined plates 102 and 103. The height from the lower ends of the inclined plates 102 and 103 to the ridge plate 101 (the length of the DH in the vehicle height direction) was 80 mm. The angle formed by the inclined plates 102 and 103 was 60 °, and the distance between the lower ends of the inclined plates 102 and 103 (the length of the DL in the vehicle length direction) was 80 mm. The cross-sectional shape of the ridge plate 101 was an arc shape, and the radius of curvature thereof was 14 mm.

The region of the ridge plate 101 was designated as the ridge region (i). Each inclined plate 102 and 103 was evenly divided into three regions along the inclined surface. These regions were designated as the upper region (ii), the intermediate region (iii), and the lower region (iv) in order from the top. At least the lower region (iv) was located below the center of gravity Gv of the torsion beam 1.

In each of the groove-shaped cross-sectional shape and the V-shaped cross-sectional shape, the basic plate thickness t of each region (i) to (vi) was set to 4 mm. Then, the plate thicknesses of the regions (i) to (vi) were variously changed from the basic plate thickness t. The amount of change in plate thickness was set to "+0.5 mm" and "+1.0 mm".

19 to 22 show the results when the cross-sectional shape is a groove shape. 23 to 26 show the results when the cross-sectional shape is V-shaped. Of these figures, FIGS. 19 and 23 show the shear center position. 20 and 24 show the bending rigidity (vertical bending rigidity) of the DH in the vehicle height direction. 21 and 25 show the bending rigidity (front-back bending rigidity) of the DL in the vehicle length direction. 22 and 26 show torsional rigidity. Each of FIGS. 19 to 26 shows a change with respect to the result when the plate thickness is the reference plate thickness t.

The following can be said from the results shown in FIGS. 19 to 26. Both the groove-shaped cross-sectional shape and the V-shaped cross-sectional shape are open cross-sections. As shown in FIG. 19, when the cross-sectional shape is groove-shaped, the shear center position Sc increases as the plate thickness of the lower region (vi) of each side plate 3 and 4 increases. As shown in FIG. 23, even when the cross-sectional shape is V-shaped, the shear center position Sc becomes higher as the plate thickness in the lower region (iv) of each of the inclined plates 102 and 103 increases. That is, if the volume (mass) of the region below the center of gravity Gv of the torsion beam 1 increases, the shear center position Sc increases. However, in the case of the groove-shaped cross-sectional shape, the shear center position Sc rises more significantly than in the V-shaped cross-sectional shape. Therefore, it is effective to increase the shear center position Sc by making the cross-sectional shape groove-shaped and increasing the volume of the region below the center of gravity Gv of the torsion beam 1.

Further, as shown in FIGS. 20 to 22, when the cross-sectional shape is grooved, the flexural rigidity and the torsional rigidity also increase as the plate thickness in the lower region (vi) of each side plate 3 and 4 increases. Therefore, making the cross-sectional shape a groove shape and increasing the volume of the region below the center of gravity Gv of the torsion beam 1 is also effective in ensuring bending rigidity and torsional rigidity.

In Example 2, the influence of L2f / L1 and L2r / L1 on the shear center position was investigated in the torsion beam having a groove-shaped cross-sectional shape. FIG. 27 is a diagram showing a cross-sectional shape of the groove shape examined in the second embodiment. The shear center position Sc was investigated by numerical analysis of the groove-shaped cross-sectional shape shown in FIG. 27. FIG. 27 shows the shear center position Sc and the center of gravity Gv in the torsion beam 1 for reference.

With reference to FIG. 27, the groove-shaped cross-sectional shape was formed by the top plate 2, the two side plates 3 and 4, and the two corner plates 5 and 6. The cross-sectional shapes of the corner plates 5 and 6 were linear. The height from the lower ends of the side plates 3 and 4 to the top plate 2 (the length of the DH in the vehicle height direction) was 80 mm. The distance between the side plates 3 and 4 (the length of the DL in the vehicle length direction) was 80 mm.

From the length L1 of the DL in the vehicle length direction of the top plate 2, the length L2f of the DL in the vehicle length direction from the front end edge 2a of the top plate 2 to the upper end edge 3a of the front side plate 3, and the rear end edge 2b of the top plate 2. The length L2r of the DL in the vehicle length direction up to the upper end edge 4a of the rear side plate 4 was variously changed. The length L2f and the length L2r were the same. The plate thickness was constant at 4 mm.

FIG. 28 shows the results of Example 2. FIG. 28 shows the ratio to the result when L2f and L2r are 0 (zero).

The following can be said from the results shown in FIG. 28. When L2f / L1 and L2r / L1 are 0.60 or less, the shear center position Sc increases. When L2f / L1 and L2r / L1 are 0.50 or less, the shear center position Sc is effectively increased. When L2f / L1 and L2r / L1 are 0.40 or less, the shear center position Sc is more effectively increased.

The embodiments of the present invention have been described above. However, the embodiments described above are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

1: Torsion beam 2: Top plate 2a: Front edge of top plate 2b: Rear edge of top plate 3, 4: Side plate 3a, 4a: Upper edge of side plate 3b, 4b: Lower end of side plate 3c, 4c: Upper side of side plate Part 5, 6: Corner plate 3bt, 3ct, 4bt, 4ct: Length Sc: Torsion beam shear center position Gv: Torsion beam center of gravity DW: Vehicle width direction DH: Vehicle height direction DL: Vehicle length direction

Claims (4)

It is a torsion beam attached to the vehicle.
The top plate extending in the width direction of the vehicle and
A side plate connected to the front edge of the top plate and extending downward and in the width direction,
With other side plates connected to the trailing edge of the top plate and extending downward and in the width direction,
The length of the top plate in the front-rear direction of the vehicle is L1, and the length of the top plate from the front end edge to the upper end edge of the side plate connected to the front end edge is L2f. When the length in the front-rear direction from the rear end edge of the top plate to the upper end edge of the side plate connected to the rear end edge is L2r, L2f / L1 and L2r / L1 are 0.60 or less. ,
A torsion beam in which the length of the lower end portion of at least one of the two side plates located below the center of gravity of the torsion beam in the front-rear direction is longer than the length of the other portion in the front-rear direction. The torsion beam according to claim 1.
Of the one side plate, the lower end portion is a torsion beam having a tubular shape extending in the width direction. The torsion beam according to claim 1.
A torsion beam in which the thickness of the lower end of the one side plate is thicker than the thickness of the other portion. The torsion beam according to any one of claims 1 to 4.
A torsion beam in which L2f is larger than L2r.

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