JP5465776B2 - Torsion beam suspension - Google Patents

Description

  The present invention relates to a torsion beam suspension in which a pair of left and right trailing arms are connected by a torsion beam, and wheels are suspended on the pair of connected left and right trailing arms.

  In the torsion beam suspension, the base end of the left and right trailing arms is swingably provided on the body frame via the support shaft, and the left and right wheels rotate at the tip (free end) of the left and right trailing arms. The left and right trailing arms are connected by a torsion beam, and the vicinity of the free ends of the left and right trailing arms are supported by springs and dampers, respectively (see, for example, Patent Document 1).

  When a relatively low frequency vibration is transmitted from the road surface to the torsion beam suspension disclosed in Patent Document 1 via the left and right wheels while the vehicle is running, a spring or a damper follows the vibration. Therefore, the left and right trailing arms swing vertically about the support shaft (base end), and the vibration transmitted from the road surface is absorbed by the spring or damper.

  On the other hand, when the vibration transmitted from the wheel is in a relatively high frequency (100 to 200 Hz) region, the elastic vibration mode of the torsion beam and the left and right trailing arms themselves is excited, and the vibration is transmitted from the vehicle body mounting portion to be transmitted in the vehicle interior. It is considered that vibration and sound are generated. As countermeasures, it was necessary to reduce vibrations with dynamic dampers and to load heavy objects such as soundproofing materials.

  Here, the left and right wheels are usually attached to the left and right trailing arms with a camber angle. Therefore, when a slight vibration occurs in the left and right wheels, a load in the vehicle width direction acts on the left and right wheels. When the load in the vehicle width direction acts on the left and right wheels, the left and right trailing arms are twisted.

  For example, when a clockwise twist occurs in the left trailing arm and a counterclockwise twist occurs in the right trailing arm, the torsion beam elastically deforms downward and the center of the torsion beam is at the lowest position. To position. On the other hand, when the load is removed from the left and right wheels, the torsion beam is restored to the original state. Therefore, the center part of the torsion beam vibrates in the vertical direction by the slight vibration transmitted to the left and right wheels.

  The vibration in the vertical direction at the center of the torsion beam is transmitted from the center of the torsion beam to the left and right trailing arms via the torsion beam. It is conceivable that the vibration transmitted to the left and right trailing arms is transmitted to the body frame through the base end portion, and the body frame vibrates in the vertical direction. When the vehicle body frame vibrates in the vertical direction, the vibration in the vertical direction is transmitted to the vehicle body, and low-frequency road noise may occur, giving a sense of discomfort.

JP 2007-76519 A

  An object of the present invention is to provide a torsion beam suspension capable of suitably ensuring low-frequency road noise of a vehicle.

  According to the first aspect of the present invention, there is provided a torsion beam type suspension comprising a pair of left and right trailing arms each having one end pivotally supported on a vehicle body and having a wheel suspended at the other end, and each intermediate portion of the left and right trailing arms. A torsion beam extending in the vehicle width direction for connection, the torsion beam having front and rear beam wall portions in the longitudinal direction of the vehicle body and formed in an open cross section having an opening portion toward the lower side of the vehicle body. One of the front and rear beam wall portions is a wall portion having higher rigidity than the other, and among the torsion beams having the front and rear beam wall portions, at least the torsion beam in the vicinity of the intermediate portion in the vehicle width direction has the higher rigidity. Provided with a torsion beam suspension characterized by having a curved portion formed in a curved shape so as to project the wall portion of It is.

  Here, the vehicle body (vehicle body frame) is configured to have higher “front-rear direction rigidity” than “up-down direction rigidity”. The “vertical rigidity” refers to the rigidity of the vehicle body against vertical vibrations acting on the vehicle body. “Rigidity in the front-rear direction” refers to the rigidity of the vehicle body against vibrations in the front-rear direction that act on the vehicle body. Therefore, it is possible to suitably secure low-frequency road noise of the vehicle by suppressing the vertical vibration among the vibrations acting on the vehicle body (body frame).

  Therefore, in claim 1, one of the front and rear beam wall portions is a wall portion having higher rigidity than the other. Further, among the torsion beams provided with the front and rear beam wall portions, at least the vicinity (near the middle) in the vehicle width direction is formed in a curved shape so that one wall portion having high rigidity protrudes.

  According to a second aspect of the present invention, preferably, the other end of the trailing arm has a spring support portion that supports a spring for buffering, and the spring support portion is arranged in front of and behind the curved portion. It arrange | positions in one direction among directions, and the said curved part is curved toward the said spring support part side.

  According to the invention which concerns on Claim 3, Preferably, the said bending part is formed so that it may curve from one side of the said left and right trailing arms to the other.

  According to the invention of claim 4, preferably, the trailing arm and the torsion beam have a first plate thickness portion having the same plate thickness as the trailing arm and a second plate having the same plate thickness as the torsion beam. It is integrally formed of a differential pressure steel plate having a thick part.

  Here, by forming the curved portion in the torsion beam, it becomes difficult to ensure the processing accuracy of the torsion beam. For this reason, it takes time to accurately position both ends of the torsion beam at predetermined positions of the pair of left and right trailing arms. Therefore, the trailing arm and the torsion beam are integrally formed of a differential pressure steel plate.

  According to a fifth aspect of the present invention, preferably, the curved portion of the torsion beam is curved so as to protrude toward the rear of the vehicle body, and is reinforced to the rear beam wall portion of the front and rear beam wall portions. An overhang is provided.

  In the invention according to claim 1, one of the front and rear beam wall portions is a wall portion having higher rigidity than the other. By increasing the rigidity of one beam wall, the vibration (amplitude) of one beam wall is suppressed to be smaller than the vibration (amplitude) of the other beam wall. Therefore, when a force that generates vibrations in the vertical direction is applied to the vicinity of the middle portion of the torsion beam, the vicinity of the middle portion is twisted toward the one beam wall, and the vicinity of the middle portion vibrates in the diagonally up and down direction. Thereby, the vibration of the up-down direction which acts on the intermediate part vicinity of a torsion beam can be suppressed small.

  Furthermore, among the torsion beams provided with the front and rear beam wall portions, at least the middle portion in the vehicle body width direction is formed as a curved portion so that one of the rigid wall portions protrudes. Therefore, when a force generating vibration in the vertical direction is applied near the middle portion of the torsion beam, the bending portion can be vibrated in an oblique direction with respect to the vertical direction. By causing the bending portion to vibrate in an oblique direction, it is possible to reduce the vertical vibration acting near the middle portion of the torsion beam (that is, the bending portion).

  Thus, according to the first aspect, one of the front and rear beam wall portions is made to be a wall portion having higher rigidity than the other, and at least one portion of the torsion beam having a high rigidity is provided in the vicinity of the middle portion in the vehicle body width direction. Was formed in the curved portion so as to protrude. Thereby, since the vibration of the up-down direction which acts on the intermediate part vicinity of a torsion beam can be suppressed small, the low frequency road noise of a vehicle can be ensured suitably.

In the invention which concerns on Claim 2, the spring support part was provided in the other end of the trailing arm. Therefore, the rigidity of the other end of the trailing arm can be made higher than that of the one end.
Further, the bending portion was bent toward the spring support portion side. Therefore, the rigidity of the bending portion (specifically, one beam wall portion) can be increased at the other end of the trailing arm provided with the spring support portion.

  Thereby, the vibration (amplitude) of one beam wall part can be suppressed smaller than the vibration (amplitude) of the other beam wall part. By suppressing the vibration (amplitude) of one beam wall to a small value, when a force that generates vibration in the vertical direction is applied near the middle part of the torsion beam, the middle part is twisted and the middle part is Vibrates diagonally. Therefore, it is possible to further suppress the vertical vibration acting near the middle portion of the torsion beam.

  In the invention according to claim 3, the bending portion is formed to be bent from one trailing arm to the other trailing arm. Therefore, the bending portion can be gently bent over the whole. Thereby, when a bending part vibrates, it can suppress that a stress concentrates on a bending part and can ensure the durability of a torsion beam still more favorably.

  In addition, by providing the torsion beam with a curved portion, the vibration in the vertical direction acting near the middle portion of the torsion beam can be suppressed to a low level, similarly to the first to second aspects. It can be suitably secured.

  In the invention according to claim 4, since the trailing arm and the torsion beam are integrally formed of the differential pressure steel plate, it is possible to omit the trouble of accurately positioning the torsion beam having the curved portion at a predetermined position of the pair of left and right trailing arms. Can do. Accordingly, the trailing arm and the torsion beam can be easily formed without taking time and effort.

  In the invention which concerns on Claim 5, by having a reinforcement overhang | projection part in a rear beam wall part, this rear beam wall part is formed in a wall part higher in rigidity than a front beam wall part. Therefore, when vibration is transmitted from the road surface to the torsion beam and the bending portion vibrates, it is possible to prevent stress from concentrating on the bending portion, and to ensure good durability of the torsion beam.

It is the perspective view which showed the vehicle body structure provided with the torsion beam type suspension by the Example of this invention. It is a top view of the vehicle body structure of FIG. It is the figure seen from the arrow 3 direction of FIG. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. It is the figure which showed the example which the micro vibration of a comparatively high frequency (100-200 Hz) acts on the suspension by a present Example from a road surface. It is the figure which showed the example which the torsion beam of the suspension by a present Example elastically deforms. It is the figure which showed the example which the torsion beam of a suspension vibrates. It is the graph which compared the conventional example and the Example of the amplitude example of a suspension (torsion beam).

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 to 3, the vehicle body structure 10 is attached to the left and right side frames (vehicle bodies) 11 and 12 arranged in the longitudinal direction of the vehicle body and the lower portions of the left and right side frames 11 and 12. A torsion beam suspension 15 and left and right rear wheels (wheels) 18 and 19 suspended from the torsion beam suspension 15 via left and right hubs 16 and 17 are provided.

  The torsion beam suspension 15 includes a left trailing arm 21 that is rotatably provided at the lower portion of the left side frame 11, a right trailing arm 22 that is rotatably provided at the lower portion of the right side frame 12, and a pair of A torsion beam 23 extending between the left and right trailing arms 21, 22, a buffering left spring 24 and a left damper 25 supported by the left trailing arm 21, and a buffering right spring 26 supported by the right trailing arm 22 And a right damper 27.

  A front end (one end) 21 a of the left trailing arm 21 is pivotally supported by the left bracket 31 via a left support shaft 32. A left axle 33 is provided at the rear end (the other end) 21 b via the left hub 16. The rear end 21 b includes a portion that supports the lower end portion 24 a of the left spring 24 and the lower end portion 25 a of the left damper 25. The left rear wheel 18 is provided on the left axle 33. The left bracket 31 is provided at the lower part of the left side frame 11.

  The left trailing arm 21 has a plate thickness of T1, and has a left spring support portion (spring support portion) 34 provided integrally with the rear end 21b. The rear end 21 b is reinforced by the left spring support portion 34. By reinforcing the rear end 21b of the left trailing arm 21 with the left spring support portion 34, the rigidity of the rear end 21b can be made higher than that of the front end 21a.

  The left spring support portion 34 supports the lower end portion 24a of the left spring 24 for buffering. Further, a lower end portion 25 a of the left damper 25 is supported on the rear end 21 b of the left trailing arm 21 behind the left spring support portion 34.

  The right trailing arm 22 is a member symmetrical to the left trailing arm 21 and has a front end (one end) 22a pivotally supported by the right bracket 36 via a right support shaft 37 (see also FIG. 4). The right axle 38 is provided at the rear end (the other end) 22b via the right hub 17. The rear end 22b includes a portion that supports the lower end portion 26a of the right spring 26 and the lower end portion 27a of the right damper 27 (see also FIG. 4). The right rear wheel 19 is provided on the right axle 38. The right bracket 36 is provided on the lower portion 12a (see FIG. 4) of the right side frame 12.

  The right trailing arm 22 includes a right spring support portion (spring support portion) 39 (see also FIG. 4) that is formed to have a plate thickness of T1 (FIG. 5) and is provided integrally with the rear end 22b. The rear end 22 b is reinforced by a right spring support 39. By reinforcing the rear end 22b of the right trailing arm 22 with the right spring support portion 39, the rigidity of the rear end 22b can be made higher than that of the front end 22a.

  The lower end portion 26 a of the right spring 26 for buffering is supported by the right spring support portion 39. A lower end portion 27a (see FIG. 4) of the right damper 27 is supported on the rear end 22b of the right trailing arm 22 behind the right spring support portion 39.

  Thus, the left spring 24 and the left damper 25 are provided at the rear end 21 b of the left trailing arm 21, and the right spring 26 and the right damper 27 are provided at the rear end 22 b of the right trailing arm 22. Therefore, when a vibration having a relatively low frequency is transmitted from the road surface 29 to the left and right trailing arms 21 and 22 from the road surface 29 while the vehicle is running, the left spring 24 and the left damper are transmitted to the transmitted vibration. 25, the right spring 26, and the right damper 27 are caused to follow and the vibration is absorbed. Thereby, vibrations are not transmitted from the left and right trailing arms 21 and 22 to the left and right side frames 11 and 12, and low-frequency road noise of the vehicle can be suitably secured.

  On the other hand, when a relatively high frequency (100 to 200 Hz) fine vibration (fine input) is transmitted from the road surface 29 to the left and right trailing arms 21 and 22 from the road surface 29 while the vehicle is running, It is difficult to absorb the slight vibration by causing the left spring 24, the left damper 25, the right spring 26, and the right damper 27 to follow the transmitted vibration. Therefore, the torsion beam 23 is formed in a curved shape in order to cope with a case where a slight vibration with a relatively high frequency (100 to 200 Hz) is transmitted.

  Specifically, as shown in FIG. 2, the torsion beam 23 has a vehicle width for connecting an intermediate portion (predetermined position) 21c of the left trailing arm 21 and an intermediate portion (predetermined position) 22c of the right trailing arm 22. It extends in the direction (left-right direction of the vehicle body). The torsion beam 23 has a curved portion 41 formed so as to bend (project) toward the rear of the vehicle body from the middle portion 21c of the left trailing arm 21 to the middle portion 22c of the right trailing arm 22 in plan view. The reason why the bending portion 41 of the torsion beam 23 is formed so as to bend (project) toward the rear of the vehicle body will be described in detail later.

  As shown in FIG. 4, the bending portion 41 is formed in an inverted U-shaped cross section with a plate thickness T2. The curved portion 41 includes a front beam wall portion 43 bent downward from the beam top portion 42 toward the front of the vehicle body, a rear beam wall portion 44 bent downwardly from the beam top portion 42 toward the vehicle body, and a rear beam wall portion. And a reinforcing overhanging portion 45 projecting toward the rear of the vehicle body from the lower end portion 44a.

  The torsion beam 23 has an opening 46 that opens toward the lower side of the vehicle body by bending the front beam wall 43 in a downward gradient and the rear beam wall 44 in a downward gradient. Therefore, the middle portion 41a (FIG. 2) of the torsion beam 23 and the vicinity thereof can be relatively allowed to vibrate in the vertical direction.

  By providing the reinforcing overhang 45 at the lower end 44 a of the rear beam wall 44, the lower end 44 a of the rear beam wall 44 is reinforced by the reinforcing overhang 45. Therefore, the rear beam wall portion 44 is formed in a wall portion having higher rigidity than the front beam wall portion 43.

  That is, as shown in FIGS. 1 and 2, the curved portion 41 of the torsion beam 23 is formed so that the rear beam wall portion 44 projects toward the rear of the vehicle body in the entire region E in the vehicle width direction. As a result, the intermediate portion 41 a in the vehicle width direction of the curved portion 41 is separated from the virtual straight line 48 by a distance L1 behind the vehicle body. The virtual straight line 48 is a straight line extending in the vehicle width direction from the left end 23 a to the right end 23 b of the torsion beam 23.

  As described above, the bending portion 41 is formed to be bent in the entire region E in the vehicle width direction from the left trailing arm 21 to the right trailing arm 22. The bending portion 41 is gently bent over the entire torsion beam 23. Therefore, when the vibration from the wheel is transmitted to the torsion beam and the bending portion 41 vibrates, the concentration of stress on the bending portion 41 is suppressed. By suppressing the concentration of stress on the curved portion 41, the durability of the torsion beam 23 can be ensured satisfactorily.

  On the left end portion 41b side of the curved portion 41, a left spring support portion 34 is disposed on the rear end (one direction) of the left end portion 41b. Further, on the right end portion 41c side of the bending portion 41, a right spring support portion 39 (see also FIG. 4) is disposed on the rear end (one direction) of the right end portion 41c. That is, the bending portion 41 is bent rearward of the vehicle body toward the left spring support portion 34 side and the right spring support portion 39 side.

  According to the torsion beam 23, it is possible to suppress the influence of low-frequency road noise acting on the vehicle when a relatively high frequency (100 to 200 Hz) fine vibration (fine input) is transmitted. The reason why the influence of the low-frequency road noise acting on the vehicle is suppressed will be described in detail with reference to FIGS.

  By the way, the torsion beam 23 has a curved portion 41. For this reason, it is necessary to bend the torsion beam 23 into a curved shape, and it is difficult to ensure the processing accuracy of the torsion beam 23. Therefore, the left end portion (one of both end portions) 23a of the torsion beam 23 is accurately positioned to the intermediate portion 21c of the left trailing arm 21, and the right end portion (the other end of both ends) 23b of the torsion beam 23 is positioned to the right trailing arm. It takes time to position the intermediate portion 22c of the 22 with high accuracy. Therefore, the pair of left and right trailing arms 21 and 22 and the torsion beam 23 are integrally formed (press-molded) with the differential pressure steel plate 52 shown in FIG.

  As shown in FIG. 5, the differential pressure steel plate 52 is tailored blanks in which a first plate thickness portion 53 and a second plate thickness portion 54 having different plate thicknesses are integrally formed. The first plate thickness portion 53 is a portion where a pair of left and right trailing arms 21 and 22 (see FIG. 1 for the left trailing arm 21) is formed, and the same plate thickness T1 as the pair of left and right trailing arms 21 and 22 Is formed. The second plate thickness portion 54 is a portion where the torsion beam 23 is formed, and is formed to the same plate thickness T2 as the torsion beam 23.

  By press forming the differential pressure steel plate 52, the pair of left and right trailing arms 21 and 22 and the torsion beam 23 can be integrally formed with different plate thicknesses. That is, the pair of left and right trailing arms 21 and 22 and the torsion beam 23 can be integrally formed so that the pair of left and right trailing arms 21 and 22 has a plate thickness T1 and the torsion beam 23 has a plate thickness T2.

  Therefore, it is possible to save the trouble of accurately positioning the torsion beam 23 having the curved portion 41 on the intermediate portion 21c (FIG. 2) of the left trailing arm 21 and the intermediate portion 22c of the right trailing arm 22, and a pair of left and right trays The ring arms 21 and 22 and the torsion beam 23 can be easily formed without labor.

  Here, as described above, an example in which the torsion beam 23 vibrates when a relatively high frequency (100 to 200 Hz) fine vibration (fine input) is transmitted from the road surface 29 will be described with reference to FIGS.

  As shown in FIG. 6A, while the vehicle is traveling, a slight vibration (fine input) of a relatively high frequency (100 to 200 Hz) is transmitted from the road surface 29 to the left trailing arm 21 via the left rear wheel 18. A relatively high frequency (100 to 200 Hz) fine vibration (fine input) is transmitted from the road surface 29 to the right trailing arm 22 via the right rear wheel 19.

  At this time, it is difficult to absorb the slight vibration by causing the left spring 24 and the left damper 25 to follow the slight vibration at a relatively high frequency (100 to 200 Hz), and the minute vibration at a relatively high frequency (100 to 200 Hz). It is difficult to absorb the slight vibration by causing the right spring 26 and the right damper 27 to follow.

  Here, for example, it is assumed that the left rear wheel 18 is attached to the left trailing arm 21 with a camber angle α, and the right rear wheel 19 is attached to the right trailing arm 22 with a camber angle α. That is, the left and right rear wheels 18 and 19 are provided in an A shape (so-called negative camber) that spreads downward. When a slight vibration is transmitted to the left and right rear wheels 18 and 19 as indicated by the arrow A in the vertical direction, an outward load F1 acts on the grounding portion 18a of the left rear wheel 18 and the grounding portion 19a of the right rear wheel 19 Directional load F1 acts.

  By applying an outward load F1 to the ground contact portion 18a of the left rear wheel 18, the left trailing arm 21 is twisted via the left axle 33 (FIG. 3) of the left rear wheel 18 and the M1 is turned in the counterclockwise direction. It occurs as follows. Further, when an outward load F1 acts on the ground contact portion 19a of the right rear wheel 19, the right trailing arm 22 is twisted by the right trailing arm 22 via the right axle 38 (FIG. 3), and the M1 is rotated clockwise. Occurs like an arrow.

  As shown in FIG. 6B, the curved portion 41 of the torsion beam 23 is formed so as to bend (project) toward the rear of the vehicle body, so that the intermediate portion 41 a of the curved portion 41 is And separated by a distance L1 behind the vehicle body. The virtual straight line 48 is a straight line extending in the vehicle width direction from the left end 23 a to the right end 23 b of the torsion beam 23.

Therefore, the twist M1 is generated in the left and right trailing arms 21 and 22, so that the intermediate portion 41a is clockwise when viewed from the left side about the virtual straight line 48 (that is, the left end portion 23a to the right end portion 23b of the torsion beam 23). Elastically deform (turn). Here, when the amount of elastic deformation of the torsion beam 23 (intermediate portion 41a and its vicinity) is small, the intermediate portion 41a and its vicinity are elastically deformed by a distance S1 as shown by an arrow B in a downward gradient of an inclination angle θ1 toward the front of the vehicle ( Move).
Hereinafter, in order to facilitate understanding of the vibration of the torsion beam 23, the “intermediate portion 41a of the torsion beam 23 and its vicinity” will be described as the “intermediate portion 41a”.

As shown in FIG. 7A, when the intermediate portion 41a is elastically deformed (moved) by a distance S1 with a downward slope of the inclination angle θ1, the downward elastic deformation amount (moving amount) S1 _V of the intermediate portion 41a. Can be kept small.
Here, the downward elastic deformation amount (movement amount) S1 _V of the intermediate portion 41a is
It is expressed by S1 _V = S1 × sin θ1.
On the other hand, the intermediate portion 41a is by only elastically deformed (moved) Distance S1 is downward slope tilt angle .theta.1, the intermediate portion 41a to the vehicle body forward a distance S1 _H only elastically deformed (moved).
The elastic deformation amount of the vehicle body toward the front of the middle portion 41a (the movement amount) S1 _H is
S1 _H = S1 × cos θ1

  Here, as shown in FIG. 7 (b), by providing the reinforcing overhanging portion 45 on the rear beam wall portion 44 (lower end portion 44 a) of the torsion beam 23, the rear beam wall portion 44 is more than the front beam wall portion 43. It is formed on a highly rigid wall. Therefore, when the intermediate portion 41a of the bending portion 41 is elastically deformed (moved) downward, the elastic deformation amount (lowering amount) S2 of the rigid rear beam wall portion 44 is the elastic deformation amount (lowering amount) of the front beam wall portion 43. Amount) Suppressed smaller than S3.

  As a result, when the intermediate portion 41a of the bending portion 41 is elastically deformed (moved) downward, the intermediate portion 41a is twisted toward the front beam wall portion 43, and is inclined downward at an inclination angle θ2 in front of the vehicle body and downward. Then, it is elastically deformed (moved) as shown by arrow C. Since the intermediate portion 41a is elastically deformed (moved) with a downward gradient of the inclination angle θ2, the downward elastic deformation amount (moving amount) of the intermediate portion 41a can be suppressed small.

As shown in FIGS. 7A and 7B, the bending portion 41 of the torsion beam 23 is formed so as to bend (protrude) toward the rear of the vehicle body, whereby the amount of elastic deformation in the downward direction of the intermediate portion 41a ( (Movement amount) S1 _V can be kept small.
In addition, by providing the reinforcing overhanging portion 45 on the rear beam wall portion 44 (lower end portion 44a) of the torsion beam 23, the downward elastic deformation amount (movement amount) of the intermediate portion 41a can be suppressed. Thereby, the downward elastic deformation amount (movement amount) of the intermediate portion 41a can be sufficiently reduced.

  In other words, the curved portion 41 of the torsion beam 23 is curved toward the rear of the vehicle body, and the reinforcing beam 45 is provided on the rear beam wall 44 (lower end portion 44a), so that the torsion beam 23 (intermediate portion 41a) is provided. The inclination angle in the elastic deformation direction can be made sufficiently small (that is, sufficiently close to the horizontal direction).

  In addition, as shown in FIG. 2, a left spring support portion 34 is provided at the rear end 21 b of the left trailing arm 21, and a right spring support portion 39 is provided at the rear end 22 b of the right trailing arm 22. Therefore, the rigidity of the rear end 21b of the left trailing arm 21 can be made higher than that of the front end 21a, and the rigidity of the rear end 22b of the right trailing arm 22 can be made higher than that of the front end 22a.

  Further, the bending portion 41 of the torsion beam 23 was bent toward the left and right spring support portions 34 and 39. Therefore, the rigidity of the curved portion 41 (specifically, the rear beam wall portion 44) is set so that the rear end 21 b of the left trailing arm 21 having the left spring support portion 34 and the right trailing arm having the right spring support portion 39. 22 can be secured at the rear end 22b.

  By increasing the rigidity of the rear beam wall portion 44, the elastic deformation amount (lowering amount) S2 (see FIG. 7B) of the rear beam wall portion 44 is changed to the elastic deformation amount (lowering amount) S3 of the front beam wall portion 43. (See FIG. 7B). As a result, when the intermediate portion 41a of the bending portion 41 is elastically deformed (moved) downward, the intermediate portion 41a is further twisted toward the front beam wall portion 43, and the inclination angle θ2 (see FIG. 7 (b)) is elastically deformed (moved) with a downward gradient having a smaller inclination angle. When the intermediate portion 41a is elastically deformed (moved) with a downward gradient smaller than the inclination angle θ2, the downward elastic deformation amount (moving amount) of the intermediate portion 41a can be further reduced.

  On the other hand, when the twist M1 of the left trailing arm 21 and the twist M1 of the right trailing arm 22 are released, the torsion beam 23 returns (restores) to the state before elastic deformation. In this way, by alternately repeating the state in which the twists M1 and M1 are generated in the pair of left and right trailing arms 21 and 22, and the state in which the twists M1 and M1 are released from the pair of left and right trailing arms 21 and 22, The intermediate part 41a of the bending part 41 vibrates with a downward gradient.

  Next, an example in which the intermediate portion 41a of the bending portion 41 vibrates with a downward gradient will be described with reference to FIG.

  As shown in FIG. 8, the twist M1 is generated in the left trailing arm 21 and the twist M1 is generated in the right trailing arm 22, so that the intermediate portion 41a of the curved portion 41 is inclined as indicated by an arrow D toward the front of the vehicle body. Elastically deforms (moves) with a downward gradient of the angle θ3.

  On the other hand, when the twist M1 of the left trailing arm 21 is released and the twist M1 of the right trailing arm 22 is released, the torsion beam 23 returns (restores) to the state before elastic deformation as indicated by an arrow E.

  In this way, by alternately repeating the state in which the twists M1 and M1 are generated in the pair of left and right trailing arms 21 and 22, and the state in which the twists M1 and M1 are released from the pair of left and right trailing arms 21 and 22, The intermediate portion 41a of the bending portion 41 vibrates with a downward gradient having an inclination angle θ3 as indicated by an arrow D-arrow E. This vibration has a vibration width (hereinafter referred to as “amplitude”) S4.

Therefore, the horizontal component (hereinafter referred to as the horizontal component) S4 _H of the amplitude S4 is
S4 _H = S4 × cos θ3.
Also, a vertical component (hereinafter referred to as a vertical component) S4 _V is
It can be expressed by S4 _V = S4 × sin θ3.
As described above, the inclination angle θ3 is close to the horizontal direction (it is kept small). Thus, the horizontal component S4 _H is relatively large.

  Here, the left and right side frames 11 and 12 shown in FIG. 2 are configured to have higher “front-rear direction rigidity” than “up-down direction rigidity”. “Rigidity in the vertical direction” refers to the rigidity of the left and right side frames 11 and 12 against vibration in the vertical direction acting on the left and right side frames 11 and 12. The “front-rear direction rigidity” refers to the rigidity of the left and right side frames 11, 12 with respect to the vibration in the front-rear direction acting on the left and right side frames 11, 12.

Thus, the horizontal component S4 _H is also relatively large, when the horizontal component S4 _H is transmitted to the left and right side frames 11 and 12 are suitably restrained by the left and right side frames 11 and 12. Accordingly, even when the horizontal component S4 _H is relatively large, it is possible to prevent the horizontal component S4 _H influences by the low-frequency road noise acting on the vehicle.

On the other hand, as described with reference to FIG. 7, the inclination angle θ <b> 3 is close to (or suppressed to be small) in the horizontal direction, so that the vertical component S <b> 4 _V (that is, amplitude in the vertical direction) can be suppressed to be small. Thereby, since the vertical amplitude transmitted to the left and right side frames 11 and 12 can be kept small, it is possible to prevent the vertical component S4 _{V from} being affected by low-frequency road noise acting on the vehicle.

Thus, the low frequency road noise of the vehicle can be suitably ensured so that the horizontal component S4 _H and the vertical component S4 _V do not affect the low frequency road noise acting on the vehicle.

FIG. 9 is a graph showing the width (amplitude) of the vibration in the vertical direction of the torsion beam. The vertical axis represents the vertical amplitude of the torsion beam. In the graph, G1 indicates the amplitude S5 of the suspension in which the torsion beam described in the prior art is linearly bridged between the left and right trailing arms. A graph G2 shows the amplitude S4 _V of the suspension 15 of the present embodiment described with reference to FIGS.

As shown in FIG. 9, the suspension 15 of the embodiment can reduce the vertical amplitude S4 _V by ΔS compared to the amplitude S5 of the conventional example.

In other words, the suspension 15 according to the present embodiment includes the curved portion 41 in the torsion beam 23, and the rigidity of the rear beam wall portion 44 is ensured to be high by the reinforcing overhang portion 45 and the left and right spring support portions 34, 39. The vicinity of the intermediate portion 41a of 41 can be vibrated in an oblique direction. Thereby, the vertical amplitude S4 _V acting in the vicinity of the intermediate portion 41a of the bending portion 41 can be kept small, and the vertical amplitude S4 _V can be reduced by ΔS compared to the amplitude S5 of the conventional example.

  The torsion beam type suspension 15 of the present invention is not limited to this embodiment, and can be changed or improved as appropriate. For example, in the present embodiment, the example in which the curved portion 41 of the torsion beam 23 is formed over the entire area E between the left and right trailing arms 21 and 22 has been described. Even if at least the middle part in the vehicle width direction is formed as the curved part, the same effect can be obtained.

  In the present embodiment, the example in which the curved portion 41 is formed by increasing the rigidity of the rear beam wall portion 44 and projecting the rear beam wall portion 44 has been described. However, the present invention is not limited thereto, and the front beam wall portion is not limited thereto. Even if the curved portion 41 is formed by increasing the rigidity of 43 and projecting the front beam wall portion 43 toward the rear of the vehicle body, the same effect can be obtained.

  Further, in this embodiment, the front ends 21a, 22a of the left and right trailing arms 21, 22 are pivotally supported on the left and right side frames 11, 12, and the left and right rear wheels 18, 19 are provided at the rear ends 21b, 22b. However, the present invention is not limited to this, and the rear ends 21b and 22b can be pivotally supported by the left and right side frames 11 and 12, and the left and right rear wheels 18 and 19 can be provided at the front ends 21a and 22a. .

  Furthermore, in this embodiment, the example in which the torsion beam suspension 15 is applied to the left and right rear wheels 18 and 19 has been described. However, the present invention is not limited to this, and the torsion beam suspension 15 may be applied to the left and right front wheels. Is possible.

  Furthermore, in the present embodiment, an example in which the left and right rear wheels 18, 19 are provided in an A shape (so-called negative camber) has been described. However, the present invention is not limited to this, and the left and right rear wheels 18, 19 are reversed. Even if it is provided in a V shape (so-called positive camber), the same effect can be obtained.

  Furthermore, the vehicle body structure 10, left and right side frames 11 and 12, torsion beam suspension 15, left and right rear wheels 18 and 19, a pair of left and right trailing arms 21 and 22, and a pair of left and right trailing shown in the present embodiment. Arm intermediate portions 21c and 22c, torsion beam 23, left and right springs 24 and 26, left and right spring support portions 34 and 39, curved portion 41, front and rear beam wall portions 43 and 44, opening 46, differential pressure steel plate 52, The shapes and configurations of the first plate thickness portion 53 and the second plate thickness portion 54 are not limited to those illustrated, and can be appropriately changed.

  The present invention is suitable for application to an automobile including a torsion beam suspension in which wheels are suspended on a pair of left and right trailing arms connected by a torsion beam.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle body structure, 11, 12 ... Left and right side frame (vehicle body), 15 ... Torsion beam suspension, 18, 19 ... Left and right rear wheels (wheels), 21, 22 ... A pair of left and right trailing arms, 21a, 22a ... front end (one end), 21b, 22b ... rear end (other end), 21c, 22c ... middle part of a pair of left and right trailing arms, 23 ... torsion beam, 24, 26 ... left and right springs (springs), 34, 39 ... Left and right spring support portions (spring support portions), 41 ... curved portions, 43 and 44 ... front and rear beam wall portions, 45 ... reinforcing overhang portions, 46 ... openings, 52 ... differential pressure steel plate, 53 ... first plate thickness Part, 54 ... 2nd board thickness part, T1, T2 ... board thickness.

Claims (5)

A torsion beam suspension,
A pair of left and right trailing arms that are pivotally supported at one end and suspended at the other end by the vehicle body;
A torsion beam extending in the vehicle width direction to connect the intermediate portions of the left and right trailing arms;
It has
The torsion beam is
It has a front and rear beam wall in the longitudinal direction of the vehicle body, and is formed in an open cross section having an opening toward the lower side of the vehicle body,
One of the front and rear beam wall portions is a wall portion having higher rigidity than the other,
Of the torsion beams having the front and rear beam wall portions, at least the torsion beam in the vicinity of the intermediate portion in the vehicle width direction has a curved portion formed in a curved shape so as to project the one rigid wall portion. ing,
This is a torsion beam suspension. The other end of the trailing arm has a spring support portion that supports a buffer spring;
The spring support portion is disposed in one direction of the vehicle longitudinal direction with respect to the curved portion,
The torsion beam suspension according to claim 1, wherein the curved portion is curved toward the spring support portion.   The torsion beam suspension according to claim 1 or 2, wherein the bending portion is formed to bend from one side of the left and right trailing arms to the other.   The trailing arm and the torsion beam are integrally formed of a differential pressure steel plate having a first plate thickness portion having the same plate thickness as the trailing arm and a second plate thickness portion having the same plate thickness as the torsion beam. The torsion beam type suspension according to claim 1, wherein the torsion beam type suspension is provided. The curved portion of the torsion beam is curved so as to protrude toward the rear of the vehicle body,
The torsion beam suspension according to any one of claims 1 to 4, wherein a reinforcing overhanging portion is provided on a rear beam wall portion of the front and rear beam wall portions.

Images