JP2009255763A - Torsion beam type suspension device - Google Patents

Abstract

A torsion beam suspension device having high practicality is provided.
In a torsion beam suspension device 20, a pair of trailing arms 24 provided corresponding to left and right wheels 22 are connected by a generally flat plate-like first torsion beam 26 and a rod-like second torsion beam 28. Configure as follows. Since the torsional rigidity by the two torsion beams can be set by setting the arrangement, dimensions, etc. of the first torsion beam and the second torsion beam, which have relatively large torsional rigidity, In the development stage, the degree of freedom of design is increased, and the setting of torsional rigidity by these two torsion beams becomes easy. Therefore, with this configuration, it becomes possible to easily set the rigidity of the torsion beam appropriately.
[Selection] Figure 2

Description

  The present invention relates to a suspension apparatus mounted on a vehicle, and more particularly, to a torsion beam suspension apparatus including a pair of trailing arms and a torsion beam connecting the pair of trailing arms.

In recent years, a torsion beam suspension device as described in the following patent document, specifically, a torsion beam suspension device in which the shape of a torsion beam connecting a pair of trailing arms has been devised has been studied. .
JP 2007-216824 A JP 2001-88525 A

  The torsion beam provided by the torsion beam suspension device is not twisted when the left and right wheels operate in the same direction in the vertical direction, that is, when the left and right wheels operate in the same phase, and the left and right wheels do not operate in phase. For example, when one of the left and right wheels operates in the upward direction and the other operates in the downward direction, that is, when the left and right wheels operate in opposite phases, the structure is twisted. For this reason, when the torsional rigidity of the torsion beam is too high, the left and right wheels may be difficult to operate in reverse phase, for example. Further, since the elastic force accompanying the twist of the torsion beam acts as a roll restraining force that suppresses the roll of the vehicle body, if the torsional rigidity of the torsion beam is too low, the roll of the vehicle body may become large. For this reason, it is desired to appropriately set the rigidity of the torsion beam. To that end, it is desirable that the degree of freedom in designing the suspension device is high. This invention is made | formed in view of such a situation, and makes it a subject to provide the torsion beam type suspension apparatus with a high freedom degree of design.

  In order to solve the above-mentioned problems, a torsion beam suspension device according to the present invention connects a pair of trailing arms provided corresponding to left and right wheels by a flat plate-like first torsion beam and a rod-like second torsion beam. Configured to do.

  In the torsion beam type suspension device of the present invention, a pair of trailing arms are connected by a flat plate-like first torsion beam having a relatively low torsional rigidity and a bar-like second torsion beam having a relatively high torsional rigidity. By setting the arrangement, size, and the like of each of the first torsion beam and the second torsion beam, the rigidity of the two torsion beams is set. Therefore, for example, in the development stage, when the rigidity of the two torsion beams is slightly changed, the setting of the arrangement and dimensions of the first torsion beam is changed, and when the rigidity is significantly changed, the second torsion beam is changed. If the setting of the arrangement, dimensions, etc. is changed, the setting of rigidity becomes relatively easy. Thus, according to the suspension device of the present invention, it is possible to increase the degree of freedom in design, and it is possible to optimize the rigidity of the torsion beam.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. In the following items, items (1) to (5) correspond to claims 1 to 5, respectively.

(1) Provided in correspondence with the left and right wheels, each of which is swingably held by the vehicle body at one end and holds the wheel corresponding to itself among the left and right wheels at the other end 1 A pair of trailing arms;
A first flat torsion beam that is disposed so as to extend in the vehicle width direction and connects the pair of trailing arms;
A torsion beam suspension device comprising: a rod-shaped second torsion beam that is arranged to extend in the vehicle width direction and connects the pair of trailing arms.

  The torsion beam suspension device is configured to allow movements other than the in-phase movement of the left and right wheels, for example, the opposite phase movement of the left and right wheels during rolling of the vehicle body, by twisting the torsion beam. . For this reason, if the rigidity of the torsion beam is too high, the left and right wheels may be difficult to move in reverse phase. The elastic force accompanying the torsion beam twist acts as a roll restraining force that restrains the roll of the vehicle body. For this reason, if the torsional rigidity of the torsion beam is too low, the roll of the vehicle body may become large. That is, in the torsion beam type suspension device, it is desired to appropriately set the rigidity of the torsion beam.

  In the suspension device according to this aspect, the pair of trailing arms are connected by the flat plate-like first torsion beam having relatively low torsional rigidity and the rod-like second torsion beam having relatively high torsional rigidity. The rigidity of two torsion beams having relatively large torsional rigidity is determined by the setting of each of the two torsion beams, the size, and the like. For this reason, for example, when setting the rigidity of these two torsion beams at the stage of development of the suspension device, for example, if the rigidity is to be changed significantly, the setting of the arrangement, dimensions, etc. of the second torsion beam is changed. What is necessary is just to change arrangement | positioning of a 1st torsion beam, a dimension, etc., when changing a rigidity finely. As described above, according to the device of the aspect described in this section, it is possible to increase the degree of freedom in designing the suspension device, and it is possible to optimize the rigidity of the torsion beam.

  The “first torsion beam” described in this section may be generally flat, and for example, the edge in the longitudinal direction may be bent and the center may be flat. The “second torsion beam” described in this section may be hollow or solid. Further, the shape of the cross section of the “second torsion beam” may be a polygon or may be generally circular. The concept of “bar” described in this section includes the ratio of the length in the longitudinal direction and the length in the short direction of the cross section, that is, the aspect ratio is about 2: 1. It is.

(2) The torsion beam suspension device is provided corresponding to the rear wheel,
The torsion beam suspension device according to item (1), wherein the second torsion beam is disposed above the first torsion beam.

  The torsion beam suspension device has a structure in which the trailing arm swings around the rotation axis of one end of the trailing arm that is rotatably held by the vehicle body, and the left and right wheels swing similarly in the vertical direction. In this case, as the trailing arm swings, the wheel held by the trailing arm also swings about the rotation axis of the trailing arm. However, if the left and right wheels do not swing in the same way, for example, if the left and right wheels swing in opposite phases, the trailing arm also twists as the torsion beam twists. The swing axis of the wheel accompanying the movement deviates from the rotation axis of the trailing arm.

  This will be described in detail below with reference to the drawings. As shown in FIGS. 1A and 1B, each of a pair of trailing arms 10 provided corresponding to the left and right wheels is rotatably held on the vehicle body at one end (A, A ′). At the other end (B, B ′), a wheel (not shown) is rotatably held, and the pair of trailing arms 10 are connected by a torsion beam 12. As shown in FIG. 1A, when the left and right wheels swing in the up-down direction in phase, the rotation axes of the one end portions (A, A ′) of the pair of trailing arms 10 are coaxial with each other. Therefore, both the left and right wheels swing around an axis line (one-dot chain line) connecting point A and point A ′. On the other hand, when the left and right wheels swing in opposite phases when the vehicle body is rolled, the torsion beam tilts while twisting, as shown in FIG. However, the shear center point C of the torsion beam 12 does not move. For this reason, the swing axis of the wheel held at point B is shifted from the axis connecting point A and point A ′ and approximated to the axis connecting point A and shear center point C (one-dot chain line). can do. Further, the swing axis of the wheel held at the point B ′ can be approximated to an axis (one-dot chain line) connecting the point A ′ and the shear center point C.

  When the left and right wheels swing in phase, the axis of rotation (AA ′) of the wheels and the rotation axis of the wheels are parallel to each other. The angle, camber angle, etc. do not change much. On the other hand, when the left and right wheels swing in opposite phases, for example, when the vehicle body rolls, the axes (AC, A'C) on which the wheels swing are not parallel to the rotation axis of the wheels. For this reason, the wheel alignment changes as the wheel swings. More specifically, for example, as the axis (AC, A′C) on which the wheel swings is inclined in the vertical direction, that is, as the shear center point C is above or below, the wheel swings. The toe angle changes accordingly. More specifically, the higher the shear center point C is, the more the wheel swings closer to the vehicle body, the toe angle changes in the toe-in direction, and when the wheel swings away from the vehicle body, Changes in the toe-out direction.

  Further, during turning of the vehicle, the turning outer wheel swings so as to approach the vehicle body, and the turning inner wheel swings away from the vehicle body. That is, as the shear center point C is higher, the toe angle of the outer turning wheel changes in the toe-in direction and the toe angle of the inner turning wheel changes in the toe-out direction when the vehicle is turning. Since the torsion beam suspension device is normally provided corresponding to the rear wheel, the understeer tendency can be strengthened as the shear center point C is raised.

  The shear center of the second torsion beam with relatively high torsional rigidity and the first torsion beam with relatively low torsional rigidity is between the shear center of the first torsion beam and the shear center of the second torsion beam, and the shear center of the second torsion beam. Located near. In the apparatus according to this aspect, the second torsion beam having relatively high torsional rigidity is disposed above the first torsion beam having relatively low torsional rigidity. Therefore, according to the apparatus of the aspect described in this section, the center of shearing by these two torsion beams can be set upward, and the understeer tendency can be strengthened.

(3) Each of the pair of trailing arms has an upper bracket portion protruding upward,
One end of the second torsion beam is fixed to the upper bracket part of one of the pair of trailing arms, and the other end is fixed to the other upper bracket part of the pair of trailing arms. The torsion beam suspension device according to (2), wherein the pair of trailing arms are coupled by being fixed.

  In the apparatus according to the aspect described in this section, the second torsion beam can be disposed further upward. Therefore, according to the apparatus described in this section, the shear center can be further raised, and the understeer tendency can be further strengthened. Further, in the apparatus described in this section, the support span of the trailing arm by the two torsion beams becomes longer in the vertical direction. Therefore, according to the apparatus described in this section, for example, it is possible to make it difficult to twist the trailing arm, and it is possible to suppress a change in the camber angle accompanying the swinging of the trailing arm.

(4) Each of the pair of trailing arms has a lower bracket portion protruding downward,
One end of the first torsion beam is fixed to the lower bracket part of one of the pair of trailing arms, and the other end is fixed to the other lower bracket part of the pair of trailing arms. The torsion beam suspension device according to item (2) or (3), wherein the pair of trailing arms are coupled by being fixed.

  Also in the apparatus described in this section, as in the apparatus described in the previous section, the supporting span of the trailing arm by the two torsion beams becomes longer in the vertical direction. Therefore, according to the apparatus described in this section, for example, it is possible to suppress a change in the camber angle accompanying the swinging of the trailing arm.

  (5) The first torsion beam is disposed so as to be parallel to a virtual plane including the axis line on which each of the pair of trailing arms swings and the center of the ground contact surface of the left and right wheels. The torsion beam suspension device according to any one of items (1) to (4).

  As described above, it is desirable that the torsion beam be twisted to some extent as the pair of trailing arms swings when the vehicle body is rolled. However, it is desirable that the rigidity of the torsion beam with respect to the lateral force of the vehicle, specifically, for example, the lateral force (side force) generated on the wheels when the vehicle turns is somewhat high. Lateral force is generated in the center of the ground contact surface of the wheel in a direction perpendicular to the rotational surface of the wheel. The wheels are held at the other end of the trailing arm, and the trailing arm is held at the vehicle body at one end. For this reason, the moment centering on the point held by the body of the trailing arm is generated by the lateral force generated at the center of the ground contact surface of the wheel. In the case of adopting a flat plate as the torsion beam, as will be described in detail later, an imaginary axis including the swing axis at one end of each of the pair of trailing arms and the center of the ground contact surface of the left and right wheels is used. If a flat plate torsion beam is arranged so as to be parallel to the plane, the trailing arm support span by the flat plate torsion beam can be increased in the radial direction of the moment, and the lateral force generated when the vehicle turns The rigidity with respect to can be increased. Therefore, according to the apparatus of the aspect described in this section, for example, by adjusting the arrangement of the flat plate torsion beams, it is possible to increase the rigidity against the lateral force generated when the vehicle turns. Further, the “contact surface” described in this section means a portion of the wheel that instantaneously contacts the road surface, and does not mean a portion of the wheel that can contact the road surface when the vehicle travels.

  Hereinafter, embodiments and modifications of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention includes various aspects in which various modifications and improvements have been made based on the knowledge of those skilled in the art, including the aspects described in the above [Aspect of the Invention] section. Can be implemented.

<Configuration of suspension device>
FIG. 2 shows a vehicle suspension apparatus 20 according to the claimable invention. The suspension device 20 is a torsion beam suspension device and is disposed on the rear wheel side of the vehicle. The suspension device 20 includes a pair of trailing arms 24 provided corresponding to the left and right rear wheels 22, and a generally flat torsion beam (another torsion beam described later) that connects the pair of trailing arms 24. Hereinafter, the first torsion beam may be referred to as a “first torsion beam” 26 and a rod-like torsion beam connecting the pair of trailing arms 24 (to distinguish from the first torsion beam 26, hereinafter referred to as a “second torsion beam”). In some cases).

  The trailing arm 24 is disposed so as to extend in the front-rear direction of the vehicle, and is rotatably held on the vehicle body at one end and rotatably holds the wheel corresponding to the other end. Specifically, a bush 30 having an axial direction in the vehicle width direction is provided at the front end of the trailing arm 24, and the trailing arm 24 is held by the vehicle body via the bush 30. A carrier bracket 32 that holds the wheel 22 rotatably is fixed to the rear end of the trailing arm 24. With such a structure, the trailing arm 24 can swing up and down together with the wheels. Note that the axes of the bushes 30 provided at one end of each of the pair of trailing arms 24 are coaxial with each other.

  Further, an absorber bracket 34 is fixed to the trailing arm 24 at an intermediate portion in the axial direction thereof, and a lower end portion of a hydraulic shock absorber 36 is attached to the absorber bracket 34. An upper retainer and a lower retainer (not shown) are provided on the outer periphery of the shock absorber 36, and a compressed coil spring 38 is disposed between the two retainers.

  FIG. 3 shows an enlarged portion of the suspension device 20 from the center in the vehicle width direction to the trailing arm 24. Incidentally, the absorber bracket 34, the shock absorber 36, etc. are omitted. As shown in FIG. 3, the trailing arm 24 includes a torsion beam bracket (hereinafter referred to as an “upper torsion beam bracket” or an “upper bracket” to distinguish it from another torsion beam bracket described later) so as to protrude upward. 40) is fixed, and one end portion of the pipe-like second torsion beam 28 is fixed to the upper bracket 40 thereof. That is, one end of the second torsion beam 28 is fixed to one upper bracket 40 of the pair of trailing arms 24, and the other end is fixed to the other upper bracket 40 of the pair of trailing arms 24. Thus, the second torsion beam 28 is connected to the pair of trailing arms 24.

  A generally flat plate-like first torsion beam 26 is disposed below the second torsion beam 28 so as to extend in the vehicle width direction, and one end thereof is fixed to the trailing arm 24. That is, one end portion of the first torsion beam 26 is fixed to one of the pair of trailing arms 24 and the other end portion is fixed to the other of the pair of trailing arms 24, so that a pair of trailing arms is secured. The arm 24 is connected to the first torsion beam 26. Although the edge 42 in the longitudinal direction of the first torsion beam 26 is slightly bent, the central portion 44 that is a portion between the edges 42 has a flat plate shape, and the first torsion beam 26 is generally a flat plate. It is made into a shape.

  Further, the first torsion beam 26 is disposed so as to be inclined with respect to the trailing arm 24 in the short direction of the first torsion beam 26. If the suspension device 20 is described with reference to FIG. 4, which is a schematic diagram showing the viewpoint from the side of the vehicle, the first torsion beam 26 passes through the center point X of the bush 30 provided at one end of the trailing arm 24. Thus, it is arranged so as to be parallel to a virtual plane (dotted line) including the axis extending in the vehicle width direction and the center of the ground contact surface of the wheel, that is, the ground contact point Y. That is, the first torsion beam 26 and the virtual plane including the swing axis of each of the pair of trailing arms 24 and the centers of the ground contact surfaces of the left and right wheels are parallel to each other.

<Characteristics of suspension device>
As described in detail above, it is desirable that the torsion beam provided in the torsion beam suspension device be easily twisted to some extent from the viewpoint of allowing the left and right wheels to move in opposite phases. On the other hand, from the viewpoint of suppressing the roll of the vehicle body, it is desirable that the rigidity of the torsion beam is high to some extent. For this reason, in the torsion beam type suspension device, it is desired to optimize the rigidity of the torsion beam.

  In the present suspension device 20, a pair of trailing arms 24 are connected by a flat plate-like first torsion beam 26 having a relatively low torsional rigidity and a pipe-like second torsion beam 28 having a relatively high torsional rigidity. For this reason, in the development, improvement, etc. of the present apparatus 20, when a significant change in rigidity is desired, the setting of the arrangement, dimensions, etc. of the second torsion beam 28 may be changed, and a fine change in rigidity is desired. In such a case, the setting of the arrangement, dimensions, etc. of the first torsion beam 26 may be changed. As described above, the suspension device 20 has a high degree of design freedom, and the rigidity of the torsion beam is optimized.

  Further, in the torsion beam type suspension device, when the left and right wheels are swung in opposite phases when the vehicle body is rolled, as described in detail with reference to FIG. The wheel alignment is not parallel to the rotation axis, and the wheel alignment changes as the wheel swings. The axis on which the wheel swings when the car body rolls can be approximated to the axis that connects the shearing center point of the torsion beam and the holding point of the trailing arm by the car body. More specifically, in the torsion beam type suspension device provided on the rear wheel side, as the shear center of the torsion beam provided in the device is higher, as described above, the turning outer wheel is towed in when turning the vehicle. The turning inner wheel can be changed in the toe-out direction. That is, it is possible to strengthen the understeer tendency.

  In the present suspension device 20, the second torsion beam 28 having a relatively high torsional rigidity is disposed above the first torsion beam 26 having a relatively low torsional rigidity. Furthermore, the second torsion beam 28 is disposed above the trailing arm 24. For this reason, since the shear center in the present apparatus 20 is relatively upward, in this apparatus 20, the understeer tendency is strengthened to make the steering characteristics of the vehicle appropriate.

  In addition, the torsion beam provided in the torsion beam type suspension device is desirable to be twisted to some extent from the viewpoint of allowing the left and right wheels to move in reverse phase, but the lateral force of the vehicle, for example, the wheel when turning the vehicle It is desirable that the rigidity against the lateral force (side force) generated in the

  Lateral force is generated in the center of the ground contact surface of the wheel in a direction perpendicular to the rotational surface of the wheel. Referring to FIG. 4, the lateral force is generated in a direction perpendicular to the paper surface at the contact point Y that is the center of the contact surface of the wheel 22. The wheel 22 is held by the vehicle body via a trailing arm 24 at a center point X of a bush 30 provided at one end of the trailing arm. That is, a moment about the center point X of the bush 30 is generated by the lateral force generated at the wheel contact point Y. The first torsion beam 26 of the present apparatus 20 is disposed on an axis connecting the center point X of the bush 30 and the ground point Y of the wheel 22 and parallel to a plane perpendicular to the paper surface. For this reason, in this apparatus 20, the support span of the trailing arm by the first torsion beam 26 is elongated in the radial direction of the moment due to the lateral force, and the rigidity against the lateral force is increased.

  In the present apparatus 20, since the second torsion beam 28 is connected to the upper bracket 40, the support span of the trailing arm 24 by the two torsion beams 26, 28 is relatively long in the vertical direction. . For this reason, the trailing arm 24 is hardly twisted, and a change in camber angle due to the swinging of the trailing arm 24 is suppressed.

<Modification>
In the suspension device 20, the first torsion beam 26 is fixed to the main body of the trailing arm 24 and the second torsion beam 28 is fixed to the upper bracket 40. The first torsion beam 26 may be fixed to the bracket, and the second torsion beam 28 may be fixed to the upper bracket 40. Specifically, as shown in FIG. 5, a torsion beam bracket (hereinafter sometimes referred to as a “lower bracket” to distinguish from the upper bracket 40) 50 is provided on the trailing arm 24 so as to protrude downward. The one end part of the 1st torsion beam 26 may be fixed to the lower bracket 50. That is, one end of the first torsion beam 26 is fixed to one lower bracket 50 of the pair of trailing arms 24 and the other end is fixed to the other lower bracket 50 of the pair of trailing arms 24. Thus, the pair of trailing arms 24 may be connected to the first torsion beam 26. With this configuration, the support span of the trailing arm 24 by the two torsion beams 26 and 28 can be further increased in the vertical direction, and the camber angle can be changed as the trailing arm 24 swings. Further suppression is possible. Even in such a configuration, the first torsion beam 26 is parallel to a virtual plane including the swing axis of each of the pair of trailing arms 24 and the centers of the ground contact surfaces of the left and right wheels. It is arranged like this.

It is a figure which shows notionally the motion of the torsion beam type suspension apparatus at the time of the stroke of a right-and-left wheel. It is a perspective view which shows typically the suspension apparatus of claimable invention. FIG. 3 is a perspective view schematically showing an enlarged part of the suspension device of FIG. 2. FIG. 3 is a diagram schematically showing the suspension device of FIG. 2 in a viewpoint from the side of the vehicle. It is a perspective view which expands and schematically shows a part of suspension system of a modification.

Explanation of symbols

  20: torsion beam type suspension device 22: wheels 24: one pair of trailing arms 26: first torsion beam 28: second torsion beam 40: upper bracket 50: lower bracket

Claims (5)

A pair of trays provided corresponding to the left and right wheels, each of which is swingably held by the vehicle body at one end, and rotatably supports the wheel corresponding to itself among the left and right wheels at the other end. A ring arm,
A first flat torsion beam that is disposed so as to extend in the vehicle width direction and connects the pair of trailing arms;
A torsion beam suspension device comprising: a rod-shaped second torsion beam that is arranged to extend in the vehicle width direction and connects the pair of trailing arms. The torsion beam suspension device is provided corresponding to the rear wheel,
The torsion beam type suspension device according to claim 1, wherein the second torsion beam is disposed above the first torsion beam. Each of the pair of trailing arms has an upper bracket portion protruding upward,
One end of the second torsion beam is fixed to the upper bracket part of one of the pair of trailing arms, and the other end is fixed to the other upper bracket part of the pair of trailing arms. The torsion beam suspension device according to claim 2, wherein the torsion beam suspension device connects the pair of trailing arms by being fixed. Each of the pair of trailing arms has a lower bracket portion protruding downward,
One end portion of the first torsion beam is fixed to the lower bracket portion of one of the pair of trailing arms, and the other end portion is fixed to the other lower bracket portion of the pair of trailing arms. The torsion beam type suspension device according to claim 2 or 3, wherein the pair of trailing arms are connected by being fixed.   2. The first torsion beam is disposed so as to be parallel to a virtual plane including an axis line on which each of the pair of trailing arms swings and a center of a ground contact surface of left and right wheels. The torsion beam type suspension device according to any one of claims 4 to 4.

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