JP2008018924A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device capable of achieving a higher level of both steering stability performance, riding comfort performance and noise / vibration performance.
A suspension device including an axle carrier that rotatably supports an axle, and a plurality of links that extend from a vehicle body side mounting portion and are connected to the axle carrier, wherein the plurality of links are connected to the axle. On the upper or lower side in the vehicle vertical direction, the first link and the second link intersect each other when viewed from the top of the vehicle, and the upper side or the side opposite to the side on which the first and second links are provided or the axle. The third link is provided on the lower side.
[Selection] Figure 4

Description

  The present invention relates to a suspension device that supports a wheel by a plurality of links.

Conventionally, as an independent suspension type suspension device that supports a wheel by a plurality of links, for example, as disclosed in Patent Document 1, an axle carrier that rotatably supports an axle is provided in a single vehicle that extends in the vehicle longitudinal direction. A suspension device supported by a link (trailing arm) and a plurality of links extending in a vehicle width direction (hereinafter referred to as a vehicle width direction) is known. In this suspension device, the vehicle longitudinal load (hereinafter referred to as longitudinal force) applied to the wheels is mainly supported by the trailing arm, and the vehicle width direction load (hereinafter referred to as lateral force) applied to the wheels is mainly supported by a plurality of links. ing.
JP-A-5-104921

  In general, in order to improve the steering stability performance of the suspension, the longitudinal rigidity, which is the rigidity against the longitudinal force, the lateral rigidity, which is the rigidity against the lateral force, and the rigidity against the load in the rotational direction (toe direction) applied to the wheel in the top view of the vehicle It is necessary to increase the toe rigidity, which is. Even in the conventional technology of the above type, it is possible to increase the above three rigidity to some extent. However, for that purpose, it is necessary to increase the bush rigidity of the vehicle body side mounting portion or axle carrier side mounting portion of the trailing arm or link. However, if the bush rigidity of these mounting portions is increased, the impact / vibration input from the road surface to the wheel is easily transmitted to the vehicle body, and the riding comfort and noise / vibration deteriorate. Since the upper limit that can increase the bush rigidity is restricted in view of ensuring the riding comfort performance, there is a problem that the bush rigidity cannot be increased to a level that can satisfy the steering stability in practice.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to provide a steering suspension performance and a ride comfort / noise / vibration performance in an independent suspension system that supports a wheel by a plurality of links. The object is to provide a suspension device that is compatible at a high level.

  In order to achieve the above object, in the suspension device of the present invention, a suspension device including an axle carrier that rotatably supports an axle, and a plurality of links that extend from a vehicle body side mounting portion and are connected to the axle carrier. The plurality of links have a first link and a second link that intersect with each other as viewed from the top of the vehicle, on the upper or lower side of the vehicle in the vehicle vertical direction, and the first and second links are provided. The third link is provided on the upper side or the lower side opposite to the side and the axle.

  Therefore, the steering stability is improved only by the action of the link arrangement crossed in the top view of the vehicle, and the bush rigidity of the link mounting part can be optimally tuned for riding comfort and noise / vibration performance. Riding comfort, noise and vibration performance can be achieved at a high level.

  Hereinafter, the best mode for realizing the suspension device of the present invention will be described with reference to the drawings.

[Configuration of Example 1]
1 to 4 show a suspension device 1 according to a first embodiment in which the present invention is applied to a rear suspension on the rear wheel side of a vehicle. FIG. 1 is an overall perspective view of the suspension device 1, and FIGS. 2 to 4 show the left wheel side of the suspension device 1. 2 is a side view, FIG. 3 is a front view, and FIG. 4 is a plan view. Both show a neutral state where the suspension stroke amount is zero. Since the right wheel side has the same configuration as the left wheel side, description thereof is omitted.

  As shown in FIG. 1, the suspension device 1 includes an axle carrier 2 that rotatably supports an axle A, a strut 3 that elastically supports a load in the vertical direction of the vehicle and absorbs an impact, and the axle carrier 2 in the vertical direction of the vehicle. And a plurality of links 41 to 43 and a trailing arm 5 that are fixed to the vehicle body so as to be swingable. The plurality of links 41 to 43 extend from the vehicle body side attachment portion in the vehicle width direction and are attached to the axle carrier 2.

  As shown in FIG. 2, the axle carrier 2 includes a plurality of support members extending radially from the axle A, that is, a first lower link support member 21, a second lower link support member 22, an upper link support member 23, and a strut. And a support member 24.

(Strut)
The strut support member 24 extends from the axle A to the vehicle lower side, the vehicle rear side, and the vehicle width direction inner side, and the strut 3 is connected to the strut wheel side attachment portion 24a at the end of the wheel W outer diameter side. The strut 3 is installed in the vertical direction of the vehicle, and its upper end is connected to the vehicle body by a strut vehicle body side mounting portion 3a. The strut 3 has a coil spring 31 that supports a load in the vertical direction of the vehicle and absorbs an impact, and a shock absorber 32 that attenuates vibration in a coaxial manner.

(Upper link)
The upper link support member 23 extends from the axle A to the rear of the vehicle, above the vehicle, and slightly inward in the vehicle width direction, and an upper link wheel side attachment portion 23a is provided at an end on the outer diameter side of the wheel W. . An upper link vehicle body side attachment portion 43a, which is an attachment portion of the upper link 43 to the vehicle body side, is provided at substantially the same height behind the vehicle with respect to the upper link wheel side attachment portion 23a (see FIG. 2). The upper link 43 extends from the upper link vehicle body side attachment portion 43a to the vehicle width direction outer side and the vehicle front side, and is connected to the upper link wheel side attachment portion 23a.

  The upper link 43, along with first and second lower links 41 and 42, which will be described later, bears camber rigidity and other rigidity, and complements other rigidity such as toe rigidity which will be described later by the first and second lower links 41 and 42. Has the effect of

(Lower link)
The first lower link support member 21 extends from the axle A in front of the vehicle, below the vehicle, and inward in the vehicle width direction, and a first lower link wheel side attachment portion 21a is provided at an end of the wheel W outer diameter side. ing. The second lower link support member 22 extends from the axle A in front of the vehicle, below the vehicle, and slightly inward in the vehicle width direction, and has a second lower link wheel side mounting portion 22a at an end on the outer diameter side of the wheel W. Is provided. The first lower link wheel side mounting portion 21a is provided behind the vehicle, below the vehicle, and inside in the vehicle width direction with respect to the second lower link wheel side mounting portion 22a (see FIGS. 2 and 3).

  The first and second lower link vehicle body side attachment portions 41a and 42a, which are attachment portions to the vehicle body side of the first and second lower links 41 and 42, are both provided in front of the vehicle and below the vehicle with respect to the axle A. And is connected to the rear suspension member 6. The rear suspension member 6 is fixed to the vehicle body via a rubber insulator (not shown). The first lower link vehicle body side mounting portion 41a is provided in front of the vehicle, above the vehicle, and outside in the vehicle width direction with respect to the second lower link vehicle body side mounting portion 42a (see FIGS. 2 and 3).

  The first lower link vehicle body side mounting portion 41a is provided in front of and above the vehicle with respect to the first lower link wheel side mounting portion 21a. The second lower link vehicle body side attachment portion 42a is provided behind the vehicle and below the vehicle with respect to the second lower link wheel side attachment portion 22a (see FIGS. 2 and 3).

  The first lower link 41 extends from the first lower link vehicle body side mounting portion 41a to the vehicle width direction outer side, the vehicle lower side and the vehicle rear side, and is connected to the first lower link wheel side mounting portion 21a. The second lower link 42 extends from the second lower link vehicle body side attachment portion 42a to the outside in the vehicle width direction, above the vehicle and forward of the vehicle, and is connected to the second lower link wheel side attachment portion 22a. Therefore, the first lower link 41 and the second lower link 42 do not intersect at one point and are not parallel to each other, and are in a so-called twisted position, and are provided so as to intersect (hereinafter referred to as a cross) when viewed from above the vehicle (see FIG. 4).

(Trailing arm)
The trailing arm 5 supports the axle carrier 2 in the vehicle front-rear direction so as to be swingable in the vehicle vertical direction. The trailing arm 5 extends from the trailing arm vehicle body side mounting portion 5 a, which is a vehicle body side mounting portion, to the rear of the vehicle and slightly below the vehicle, and is connected to the axle carrier 2.

  The trailing arm vehicle body side mounting portion 5a is a cylindrical rubber bush provided with a shaft in the vehicle width direction, and the trailing arm 5 is rotatable in the vehicle vertical direction around the bush shaft. The bushing of the trailing arm body side mounting portion 5a of the first embodiment is set to have low rigidity not only in the axial direction (thrust direction) but also in the direction perpendicular to the axis (radial direction), and absorbs shock and vibration. Is expensive.

  In addition to the trailing arm 5, if the axle carrier 2 is supported in the vehicle front-rear direction, a radius rod or a semi-trailing arm provided with a large angle with respect to the vehicle width direction in the vehicle top view. There may be.

(Link mounting part)
The wheel side mounting portions 21a and 22a and the vehicle body side mounting portions 41a and 42a of the first and second lower links 41 and 42, and the wheel side mounting portion 23a and the vehicle body side mounting portion 43a of the upper link 43 are respectively in the vehicle longitudinal direction. It is a cylindrical (inner cylinder outer cylinder type) rubber bush provided with a shaft. Specifically, as shown in FIG. 4, bush shafts such as link end attachment portions 21 a and 41 a are provided in a direction perpendicular to the axis of the link member of each link 41 to 43 in the vehicle top view. These bushes are commonly used in suspension link mounting parts, and function as link swinging shafts by twisting in the direction around the shafts, and at the same time, impact and vibration from the road surface are caused by their elastic deformation and damping action. Absorb.

  In general, the bush of the suspension link mounting portion has a characteristic that rigidity is higher in the direction perpendicular to the axis (radial direction) than in the axial direction (thrust direction). All of the bushes of the first embodiment are set to have low rigidity even in the radial direction and have a high impact / vibration absorbing function.

[Operation of Example 1]
(Front / back rigidity)
The longitudinal stiffness, which is the stiffness with respect to the vehicle longitudinal direction input to the wheel W (hereinafter referred to as the longitudinal input), stabilizes the behavior of the vehicle by maintaining the posture of the wheel W during braking as intended. Therefore, in order to improve the steering stability performance, it is required to increase the longitudinal rigidity. In addition, with respect to a minute longitudinal force that is input to the wheel W when the protrusion is overtaken, longitudinal compliance is ensured by the axial deflection of each link mounting portion bush that is provided with a shaft substantially in the longitudinal direction of the vehicle.

  FIG. 5 shows a schematic top view of the suspension device 1 of the first embodiment when viewed from the vehicle. The wheel center that is the wheel rotation center, that is, the displacement of the wheel W when the front / rear input F1 is present on the axle A is indicated by a broken line (before input) and a solid line (after input). The force generated in the suspension device 1 by the front / rear input F1 is indicated by an arrow.

  In the first embodiment, the bushing of the trailing arm vehicle body side attachment portion 5a is set to have low rigidity in the radial direction in order to improve riding comfort performance. Therefore, if the wheel W has the front / rear input F1, the wheel W connected to the trailing arm 5 can be displaced in the vehicle front / rear direction due to the bending of the bush. However, since the first and second lower links 41 and 42 are arranged so as to intersect with each other when viewed from the top of the vehicle, the displacement is suppressed as follows.

  If there is a front / rear input F1 on the wheel W, the wheel side mounting portions 21a, 22a and the vehicle body side mounting portions of the first and second lower links 41, 42 are caused by displacement of the first and second lower links 41, 42 when viewed from the top of the vehicle. The bushes 41a and 42a are twisted in the bush axis bending direction. At the same time, in these attachment portions 21a, 22a, 41a, and 42a, reaction forces f1 to f4 against the torsional force due to the front and rear input F1 are generated due to the rigidity in the bushing shaft bending direction.

  The first and second lower links 41 and 42 are crossed when the vehicle is viewed from above. Therefore, if the wheel W has the front / rear input F1, a compressive force acts on one of these links 41, 42, and a tensile force acts on the other. For example, when there is an input F1 in the front direction of the vehicle, a component of a force to compress the first lower link 41 in the axial direction of the link member (hereinafter referred to as the link axial direction) acts. On the other hand, a component of a force that pulls the link member in the link axial direction acts on the second lower link 42. At the same time, the first and second lower links 41 and 42 generate reaction forces f5 and f6 against the force component by the front and rear input F1 due to the rigidity in the link axial direction.

  The front-rear input F1 is supported by the entire reaction force f1 to f6. Among them, the reaction forces f5 and f6 due to the rigidity in the link axis direction are dominant, and the reaction forces f1 to f4 due to the bush rigidity are reduced by the reaction forces f5 and f6. Accordingly, the contribution of bush rigidity to the entire rigidity with respect to the front / rear input F1 is reduced. In other words, most of the front-rear input F1 is received by the reaction forces f5 and f6 due to the link rigidity, and as a result, the torsional force of the bush and the reaction forces f1 to f4 are reduced. Therefore, the amount of elastic deformation of the bush is reduced, and the amount of displacement of the wheel W in the longitudinal direction of the vehicle is small.

  As described above, since the first and second lower links 41 and 42 are crossed in the vehicle top view, the longitudinal rigidity is not based on the bush rigidity, but is the link axial rigidity against the compression and tension in the axial direction of the link member. Secured by.

(Lateral stiffness and toe stiffness)
Lateral rigidity, which is rigidity against lateral force, and toe rigidity against load in the toe direction stabilize the behavior of the vehicle by maintaining the posture of the wheel during turning as intended. Therefore, in order to improve the steering stability performance, it is required to increase the lateral rigidity and toe rigidity. As in the first embodiment, in a suspension device that supports a wheel by a trailing arm extending in the vehicle longitudinal direction and a plurality of links extending in the vehicle width direction, lateral rigidity and toe rigidity are mainly used. I am in charge of multiple links.

  In a suspension device of this type having a trailing arm, as will be described later, when a lateral force is input, an input in the vehicle longitudinal direction is generated at the center of the wheel rotation, and the displacement in the vehicle longitudinal direction and the toe direction with respect to the lateral force is generated. Arise.

  Since the suspension device 1 according to the first embodiment crosses the first and second lower links 41 and 42 in the vehicle top view, the front and rear rigidity is high as described above. In addition to the bush rigidity, the link axial rigidity generates a reaction force against the displacement in the vehicle longitudinal direction and the toe direction generated by the lateral force. As described above, in the suspension device of the above type, the longitudinal rigidity affects the rigidity against the lateral force (specifically, the lateral rigidity and the toe rigidity). As a result, lateral rigidity and toe rigidity are also increased.

  Most of the longitudinal force and lateral force input to the ground contact point of the wheel W act on the first and second lower links 41 and 42 provided below the vehicle with respect to the axle A. In the first embodiment, since the first and second lower links 41 and 42 are crossed, the above-described action of improving the front-rear rigidity, the lateral rigidity, and the toe rigidity is improved by the link axial direction rigidity regardless of the bush rigidity. Can be obtained.

[Effects of the first embodiment in comparison with the prior art]
Performance required for the suspension device includes steering stability performance and noise / vibration performance. In order to improve the steering stability performance, it is required to increase the longitudinal rigidity, lateral rigidity, and toe rigidity. On the other hand, in order to improve riding comfort performance such as noise / vibration performance, the suspension device is required to have characteristics that make it difficult to transmit road surface input applied to the wheels to the vehicle body side member. Specifically, it is required to reduce the rigidity of the bush at the connecting portion between the suspension link and the axle carrier or the vehicle body side member.

  For example, in a trailing arm suspension device (hereinafter referred to as a conventional technology) having one upper link and two parallel lower links as described in Patent Document 1, both the steering stability performance and the ride comfort performance are Since it is going to be achieved by adjusting the bush rigidity, these performances cannot be sufficiently achieved. That is, in order to increase the longitudinal rigidity, lateral rigidity, and toe rigidity that affect the steering stability performance, the rigidity of the bush is increased. However, if the bush rigidity is increased, the noise / vibration performance deteriorates. Therefore, in the conventional technology in which the steering stability performance and the noise / vibration performance are both affected by the bush rigidity, the above two performances cannot be achieved at the same time.

  Hereinafter, in the prior art, a case is considered in which the bush rigidity of the lower link both ends mounting portion and the bushing rigidity of the trailing arm vehicle body side mounting portion are set low as in the first embodiment.

(Previous rigidity in the prior art)
FIG. 6 is a schematic top view of a conventional suspension device. The wheel displacement is indicated by a broken line (before input) and a solid line (after input) when the wheel center has a front-rear input F1 (see FIG. 5) having the same size as that of the first embodiment. The force generated in the suspension device 1 by the front / rear input F1 is indicated by an arrow.

  If the wheel has the front / rear input F1, the wheel of the lower link and the bush of the vehicle body side mounting portion are twisted in the bushing axis bending direction due to the displacement of the lower link in the vehicle top view. At the same time, reaction forces f1 ′ to f4 ′ with respect to the torsional force generated by the front / rear input F1 are generated in these mounting portions due to the rigidity in the bushing axis bending direction.

  In the prior art, the two lower links are arranged side by side in the vehicle width direction without crossing in the vehicle top view. For this reason, in these lower links, a compressive force and a tensile force are not generated in the link axial direction by the front-rear input F1. The two lower links can be rotated around the vehicle body side mounting portion while maintaining a substantially parallel positional relationship with each other.

  Therefore, no reaction force is generated in the lower link due to the axial rigidity of the link member. All the front and rear inputs F1 are received by reaction forces f1 ′ to f4 ′ due to bush rigidity. That is, the reaction force against the front / rear input F1 generates bush rigidity. As a result, the torsional force of the bush and the reaction forces f1 ′ to f4 ′ increase. Therefore, the amount of elastic deformation of the bush, that is, the amount of displacement of the lower link is large, and the amount of displacement of the wheel in the longitudinal direction of the vehicle is large.

  As described above, in the prior art, when a low-rigidity bush is used as in the first embodiment, when there is a front / rear input F1 having the same size as in the first embodiment, the amount of displacement of the wheel in the vehicle front-rear direction is determined. Is larger than that of the first embodiment, and therefore the longitudinal rigidity is low. Only the front and rear rigidity lower than that of the first embodiment can be obtained by the link reaction forces f5 and f6 that are generated when the suspension device 1 of the first embodiment is similar. In other words, in order to increase the longitudinal rigidity by reducing the amount of displacement of the vehicle in the longitudinal direction of the vehicle as in the first embodiment, it is necessary to use a bush having higher rigidity than that in the first embodiment.

(Transverse stiffness and toe stiffness in the prior art)
FIG. 7 is a schematic top view of a conventional suspension device. The displacement of the wheel when the lateral force F2 is input to the wheel is indicated by a broken line (before input) and a solid line (after input).

  In a suspension device of this type having a trailing arm and a plurality of links, when a lateral force F2 is input to the wheels, structural displacement of the wheels in the vehicle longitudinal direction and the toe direction may occur. When lateral force is input to the wheel contact point, the trailing arm is viewed from the top of the vehicle around the mounting portion due to bending of the bushing of the mounting portion of the trailing arm body side (and bending deformation of the trailing arm itself). Move slightly to draw an arc.

  Along with the rotational movement of the trailing arm, the wheels connected to the trailing arm are displaced in the toe direction, in other words, in the vehicle longitudinal direction in addition to the vehicle width direction. Furthermore, the bending tendency of the bush of the link mounting portion and the trailing arm mounting portion is further increased, so that the tendency of the displacement becomes larger.

  As described above, in the suspension device of the above type, the lateral force F2 is displaced not only in the vehicle width direction but also in the toe direction and the vehicle longitudinal direction. In the prior art, the two lower links are arranged side by side in the vehicle width direction without crossing in the vehicle top view. For this reason, in these lower links, a compressive force and a tensile force are not generated in the link axial direction due to the longitudinal displacement caused by the lateral force F2.

  Therefore, the lower link does not generate a reaction force due to the axial rigidity of the link member corresponding to the compression force and the tensile force. Therefore, the amount of elastic deformation of the bush, that is, the amount of displacement of the lower link is large, and the amount of displacement of the wheels in the toe direction and the vehicle longitudinal direction due to the input of the lateral force F2 is large. As a result, lateral stiffness and toe stiffness are reduced.

  As described above, in the prior art, when the low-rigidity bush is used as in the first embodiment, when the lateral force F2 having the same magnitude as that in the first embodiment is input, the displacement of the wheel in the vehicle longitudinal direction is detected. The amount is larger than in Example 1, and therefore the lateral rigidity and toe rigidity are low. Only the rigidity lower than that of the first embodiment can be obtained by the amount of the link reaction force generated when the suspension device 1 of the first embodiment is the same. In other words, in order to increase the lateral rigidity by reducing the displacement amount in the toe direction of the wheel and the longitudinal direction of the vehicle as in the first embodiment, it is necessary to use a bush having higher rigidity than that in the first embodiment.

(Rigidity in Example 1)
In the conventional technique, reaction force is generated only by the bush rigidity in all of the longitudinal rigidity, lateral rigidity, and toe rigidity, whereas in the first embodiment, the longitudinal input F1 and the lateral force F2 are applied as described above. On the other hand, in addition to reaction forces f1 to f4 due to bush rigidity, reaction forces f5 and f6 due to link axial rigidity are generated. Since all the three stiffnesses are shared by the link axial stiffness, the ratio of bush stiffness is reduced, and the amount of deformation of the bush is reduced. That is, even when a soft bush is used, high longitudinal rigidity and the like can be ensured.

(Experimental result)
FIG. 8 is a graph of experimental results showing the relationship between bush rigidity and lateral rigidity (including toe rigidity; the same applies hereinafter) in Example 1 and the prior art. The vertical axis represents the lateral stiffness. The horizontal axis indicates the magnitude of road noise, which is a representative value of impact and vibration that is input from the road surface to the wheel and transmitted to the vehicle body. If the bushing rigidity of the link mounting part is increased, road noise increases and riding comfort and noise / vibration deteriorate. Lowering the bush rigidity reduces road noise and improves riding comfort and noise / vibration.

  The graphs of the prior art and the first embodiment both have a downward slope. The lower the bush rigidity and the lower the road noise, the lower the lateral rigidity and the steering stability. On the other hand, if the lateral rigidity is increased to improve the steering stability, the bush rigidity needs to be increased, and road noise increases. That is, these graphs show a trade-off relationship.

  The graph of Example 1 is located above the graph of the prior art. That is, when the road noise (bush rigidity) is the same, the lateral rigidity is higher in the first embodiment than in the prior art. Further, when the lateral stiffness is the same, the road noise (bush stiffness) is smaller (lower) in the first embodiment than in the prior art. In other words, the suspension device 1 of the first embodiment eliminates the trade-off relationship between the steering stability performance and the riding comfort performance, and realizes both performances simultaneously at a high level.

(Operational effect by link arrangement)
In general, in order to increase toe rigidity, in the vehicle top view, a wide distance is provided between a link disposed in front of the vehicle with respect to the axle and a link disposed in the rear of the vehicle with respect to the axle. Increasing the bush rigidity of the link mounting portion has been performed. In the case of the first embodiment, a conventional function is realized by arranging the crossed first and second lower links 41 and 42 in front of the vehicle with respect to the axle A, and further supplementing with the upper link 43. Yes.

  That is, by crossing the first and second lower links 41, 42, toe rigidity is ensured while using soft bushes for the link attachment portions 21a, 22a, 41a, 42a. When crossed in this way, the distance between the first lower link vehicle body side mounting portion 41a and the second lower link vehicle body side mounting portion 42a, or the first lower link wheel side mounting portion 21a and the second lower link. The distance between the wheel side attachment portion 22a does not relate to the toe rigidity.

  Therefore, the crossed first and second lower links 41 and 42 can be handled as one component. In other words, both links 41 and 42 are handled together as one unit having a function of ensuring toe rigidity and other rigidity independently, and the toe rigidity is ensured while arranging them in front of the vehicle with respect to the axle A. . In addition, in the case where the toe rigidity cannot be sufficiently ensured only with the above components, the upper link 43 disposed behind the vehicle with respect to the axle A is supplemented. In this case, needless to say, it is not necessary to increase the bush rigidity of the vehicle body side and wheel side attachment portions 23a, 43a of the upper link 43.

  Alternatively, the crossed first and second lower links 41 and 42 may be disposed rearward of the vehicle with respect to the axle A, and the upper link 43 may be disposed forward of the vehicle with respect to the axle A.

  Thus, it is not necessary to widely dispose the first and second lower links 41 and 42 across the axle A in the vehicle front-rear direction in order to increase the toe rigidity. That is, the first and second lower links 41 and 42 can be collectively handled as one unit, that is, a component having a function of ensuring toe rigidity and other rigidity. Therefore, the degree of freedom in layout can be improved while reducing the number of links (or components) required for rigidity.

  Further, since the first and second lower links 41 and 42 are crossed, the dimension in the vehicle width direction can be shortened and made compact. Normally, when the dimension of the link in the vehicle width direction is shortened, the wheel alignment (wheel posture and position) during the suspension stroke is deteriorated, for example, the displacement in the vehicle width direction (scuff change) of the wheel contact point increases. . However, since the first and second lower links 41 and 42 are crossed, the actual dimensions of the first and second lower links 41 and 42 are kept long even when the dimension in the vehicle width direction is shortened. it can. For this reason, the displacement of the 1st, 2nd lower link wheel side attaching parts 21a and 22a in the vehicle width direction is suppressed at the time of a suspension stroke. Thereby, the scuff change at the time of a suspension stroke, etc. are suppressed.

  Therefore, the space in the vehicle width direction of the first and second lower links 41 and 42 can be shortened and made compact while securing the steering stability, and the layout flexibility can be improved. As a result, the floor can be lowered and the loading space can be secured.

[Effect of Example 1]
Hereinafter, the effects of the suspension device 1 of the present invention as grasped from the first embodiment will be listed.

  (1) In the suspension device 1 including an axle carrier 2 that rotatably supports the axle A and a plurality of links that extend from the vehicle body side mounting portion and are connected to the axle carrier 2, the plurality of links are: First and second links (first and second lower links 41 and 42) intersecting the vehicle A in the vertical direction of the vehicle with respect to the axle A in a vehicle top view, the first and second links are The third link (upper link 43) is provided on the upper side or the lower side opposite to the side where the axle A is provided.

Therefore, in the conventional technology, reaction force is generated only by the bush rigidity in all of the longitudinal rigidity, lateral rigidity, and toe rigidity, whereas in the present invention, the above three rigidity is crossed in the vehicle top view. Since the first and second links (the first and second lower links 41 and 42) share the rigidity in the link axial direction, the bush rigidity of the link mounting portion can be reduced by that much. Therefore, the bush rigidity can be lowered while securing the above three rigidity, and the noise and vibration performance can be improved accordingly. Therefore, compared with the prior art, there is an effect that the steering stability performance and the noise / vibration performance can be compatible at a higher level.
In addition, while ensuring steering stability, the first and second links (first and second lower links 41 and 42) are combined as one component, and the space in the vehicle width direction is shortened and made compact. This has the effect of saving and improving the layout flexibility.

  (2) The first and second links are the first and second lower links 41 and 42 disposed on the vehicle vertical direction lower side with respect to the axle A.

  Most of the longitudinal force and lateral force input to the ground contact point of the wheel W act on the first and second lower links 41 and 42 provided on the lower side in the vehicle vertical direction with respect to the axle A. By crossing the first and second lower links 41 and 42 having the majority of inputs, the effect (1) can be exhibited more efficiently.

  (3) The first and second links (first and second lower links 41 and 42) are arranged on the front side or the rear side in the vehicle front-rear direction with respect to the axle A.

  Therefore, there is an effect that the degree of freedom in layout can be improved while reducing the number of links (or components) necessary to ensure rigidity.

  (4) The third link (upper link 43) is the vehicle front-rear direction front side opposite to the side where the first and second links (first and second lower links 41, 42) are provided and the axle A. Alternatively, it is arranged on the rear side.

  In this way, the upper link 43 is disposed on the vehicle front-rear direction front side where the first and second lower links 41, 42 are provided and on the vehicle front-rear direction rear side opposite to the axle A (relative to the axle A). By doing so, the toe rigidity can be sufficiently secured.

  (5) The plurality of links include a trailing arm 5 that extends rearward from the vehicle body side attachment portion 5a and is connected to the axle carrier 2.

  Therefore, when the configuration in which the link is crossed is applied to the rear suspension having the trailing arm, the effects (1) to (4) are obtained.

  As in the first embodiment, the suspension device according to the second embodiment crosses the links when viewed from the top of the vehicle so as to ensure the front-rear rigidity of the suspension and the like and reduce the bush rigidity to improve the noise / vibration performance. However, unlike the first embodiment, it is applied not to the rear suspension but to the front suspension on the front wheel side, and suppresses a change in wheel alignment particularly during the suspension stroke.

  In other words, the front suspension generally has a steering mechanism, but the steering feeling changes sensitively with changes in wheel alignment such as camber angle and caster angle. Up to now, it has been designed in advance to reduce the wheel alignment change (geometry of suspension links), but it has been difficult to deal with various driving situations. In this second embodiment, a suspension system that is so robust in driving situation that minimizes wheel alignment change in any region of the bounding / rebounding of the wheel by applying a configuration of crossing links to the front suspension will be described. To do.

[Configuration of Example 2]
9 to 12 show a suspension device 1 according to a second embodiment in which the present invention is applied to a front suspension. FIG. 9 is an overall perspective view of the suspension device 1, and FIGS. 10 to 12 show the left wheel side of the suspension device 1. 10 is a front view, FIG. 11 is a side view, and FIG. 12 is a plan view. Both show a neutral state where the suspension stroke amount is zero. Since the right wheel side has the same configuration as the left wheel side, description thereof is omitted.

  As shown in FIG. 9, the suspension device 1 includes an axle carrier 2 that rotatably supports an axle A, a strut 3 that elastically supports a load in the vertical direction of the vehicle and absorbs an impact, and the axle carrier 2 in the vertical direction of the vehicle. And a plurality of links 45 to 48 that are fixed to the vehicle body so as to be swingable. The plurality of links 45 to 48 extend from the vehicle body side attachment portion and are attached to the axle carrier 2.

(Strut)
The strut 3 is installed in the vertical direction of the vehicle. The upper end of the strut 3 is connected to the vehicle body by the strut body side mounting portion 3a, and the lower end of the strut 3 is connected to one or both of first and second lower links 45 and 46 described later. It is connected to the axle carrier 2 by being installed. The strut 3 has a coil spring 31 that supports a load in the vertical direction of the vehicle and absorbs an impact, and a shock absorber 32 that attenuates vibration in a coaxial manner. As shown in FIGS. 10 and 11, the strut 3 has an upper end inclined inward in the vehicle width direction and rearward of the vehicle, and is installed substantially parallel to a load input shaft (not shown).

  As shown in FIGS. 10 and 11, the axle carrier 2 includes a plurality of support members extending radially from the axle A, that is, a lower link support member 25, a knuckle arm 26, a first upper link support member 27, and a second An upper link support member 28.

(Lower link)
The lower link support member 25 extends from the axle A to the lower side of the vehicle and slightly inward in the vehicle width direction, and a lower link wheel side mounting portion that is a ball joint capable of rotating in all directions at an end on the outer diameter side of the wheel W. 25a is provided.

  The first and second lower link vehicle body side attachment portions 45a and 46a, which are attachment portions to the vehicle body side of the first and second lower links 45 and 46, are cylindrical rubber bushes similar to the first embodiment, A shaft is provided in the front-rear direction. The first and second lower link vehicle body side mounting portions 45a, 46a are connected to a suspension member (not shown), and the suspension member is fixed to the vehicle body via a rubber insulator (not shown).

  The first lower link vehicle body side attachment portion 45a is provided below the vehicle with respect to the axle A and slightly forward of the vehicle with respect to the axle A. The second lower link vehicle body side mounting portion 46a is provided below the vehicle with respect to the axle A and behind the vehicle with respect to the axle A. The first lower link vehicle body side attachment portion 45a is provided at substantially the same position in the vehicle vertical direction and vehicle width direction with respect to the second lower link vehicle body side attachment portion 46a (see FIGS. 11 and 12).

  The first and second lower link vehicle body side attachment portions 45a and 46a are provided at substantially the same position as the lower link wheel side attachment portion 25a in the vehicle vertical direction. The first lower link vehicle body side mounting portion 45a is provided slightly in front of the vehicle with respect to the lower link wheel side mounting portion 25a. The second lower link vehicle body mounting portion 46a is provided on the rear side of the vehicle with respect to the lower link wheel side mounting portion 25a (see FIGS. 10 and 11).

  The first lower link 45 extends from the first lower link vehicle body side mounting portion 45a to the outside in the vehicle width direction and is connected to the lower link wheel side mounting portion 25a. The second lower link 46 extends from the second lower link vehicle body side mounting portion 46a to the outside in the vehicle width direction and in front of the vehicle, and is connected to the lower link wheel side mounting portion 25a. (See FIG. 12).

(Upper link)
The first upper link support member 27 extends from the axle A to the rear of the vehicle, above the vehicle, and inward in the vehicle width direction, and has a first upper link wheel side mounting portion that is a ball joint at an end of the wheel W outer diameter side. 27a is provided. The second upper link support member 28 extends from the axle A in front of the vehicle, above the vehicle, and inward in the vehicle width direction, and has a second upper link wheel side mounting portion that is a ball joint at an end on the outer diameter side of the wheel W. 28a is provided. The first upper link wheel side mounting portion 27a is provided behind the second upper link wheel side mounting portion 28a, at substantially the same position in the vehicle vertical direction and slightly inward in the vehicle width direction (FIG. 11). FIG. 12). The first and second upper link wheel side mounting portions 27a and 28a are provided inside the wheel W in the vehicle vertical direction.

  The first and second upper link vehicle body side mounting portions 47a and 48a, which are the mounting portions of the first and second upper links 47 and 48 on the vehicle body side, are cylindrical rubber bushes similar to those of the first embodiment, and are substantially the same. A shaft is provided in the vehicle longitudinal direction. Specifically, the bush shafts of the first and second upper link vehicle body side mounting portions 47a and 48a are provided at right angles to the link axis direction when the vehicle is viewed from above (see FIG. 12), and the first upper when viewed from the vehicle side. The link vehicle body side mounting portion 47a is provided slightly downward to the left, and the second upper link vehicle body side attachment portion 48a is provided slightly downward to the right (see FIG. 11).

  The first upper link vehicle body side mounting portion 47a is provided slightly above the vehicle and in front of the vehicle with respect to the axle A. The second upper link vehicle body side attachment portion 48a is provided above the vehicle and behind the vehicle with respect to the axle A. The first upper link vehicle body side mounting portion 47a is provided below the vehicle and slightly in the vehicle width direction with respect to the second upper link vehicle body side mounting portion 48a (see FIGS. 10 and 11).

  The first upper link vehicle body side mounting portion 47a is provided in front of and below the vehicle with respect to the first upper link wheel side mounting portion 27a. The second upper link vehicle body side attachment portion 48a is provided behind the vehicle and slightly below the vehicle with respect to the second upper link wheel side attachment portion 28a (see FIGS. 10 and 11).

  The first upper link 47 extends from the first upper link vehicle body side mounting portion 47a to the outside in the vehicle width direction, above the vehicle and rearward of the vehicle, and is connected to the first upper link wheel side mounting portion 27a. The second upper link 48 extends from the second upper link vehicle body side mounting portion 48a outward in the vehicle width direction, slightly above the vehicle and forward of the vehicle, and is connected to the second upper link wheel side mounting portion 28a. Therefore, the first upper link 47 and the second upper link 48 are provided so as to intersect with each other when the vehicle is viewed from above (see FIG. 12).

(Steering link mechanism)
The knuckle arm 26 extends from the axle A to the rear of the vehicle, the lower side of the vehicle, and the inner side in the vehicle width direction, and a tie rod mounting portion 26a that is a ball joint is provided at an end of the wheel W on the outer diameter side. The tie rod attachment portion 26a is provided slightly below the vehicle and slightly inward in the vehicle width direction with respect to the lower link wheel side attachment portion 25a (see FIG. 10). A tie rod 44 constituting a part of the link mechanism of the steering device 7 is connected to the tie rod mounting portion 26a.

  The steering device 7 is a rack and pinion type, and when the steering wheel SW is steered, the rotation is converted into movement of the rack 7a in the vehicle width direction (see FIG. 9). A connecting portion 44a is provided at an end of the rack 7a, and an end on the inner side in the vehicle width direction of the tie rod 44 is connected to the connecting portion 44a. Therefore, the tie rod 44 moves in the vehicle width direction as the rack 7a moves. Further, the tie rod 44 is provided so as to be swingable in the vehicle vertical direction around the connecting portion 44a. The outer end of the tie rod 44 in the vehicle width direction is connected to the knuckle arm 26 via a tie rod mounting portion 26a.

  The connecting portion 44a is provided slightly in front of the vehicle with respect to the tie rod mounting portion 26a and at substantially the same position in the vehicle vertical direction. Further, the connecting portion 44a is provided at substantially the same position slightly below the vehicle and in the vehicle width direction with respect to the first lower link vehicle body side mounting portion 45a (see FIGS. 10 and 11). Therefore, the tie rod 44 is slightly shorter than the first lower link 45 and is provided substantially parallel to the first lower link 45. The tie rod 44 rotates the wheel W (axle carrier 2) in the toe direction around a kingpin shaft described later by movement in the vehicle width direction.

  When the wheel W (axle carrier 2) rotates in the toe direction, the first and second upper link vehicle body side mounting portions 47a and 48a are bent by the bush, the axle carrier 2 is slightly rotated in the direction around the axle, etc. The first and second upper links 47 and 48 are appropriately displaced, and minute displacements in the vehicle width direction of the first and second upper link wheel side mounting portions 27a and 28a are allowed. For this reason, if the width in the vehicle front-rear direction of the first and second upper link wheel side mounting portions 27a and 28a is appropriately set, there is no problem in turning by crossing the first and second upper links 47 and 48. .

[Operation of Example 2]
Changes in wheel alignment such as camber angle and caster angle during suspension stroke are mainly conditioned by the suspension link and arm geometry. In other words, the geometry determines the toe-direction rotation axis of the wheel at the time of turning, that is, the kingpin axis (including the virtual kingpin axis; the same applies hereinafter). If the position or inclination of the kingpin axis changes during the suspension stroke, it will cause a change in wheel alignment, which will affect the steering stability performance.

  Hereinafter, the points that are the centers of rotation of the wheels in the toe direction during steering on the upper link side and the lower link side are referred to as upper and lower pivot points, respectively. Conventionally, as a method of setting the kingpin shaft, when the A-type arm member is used on the upper side and the lower side, a method of using a straight line connecting the upper side and lower side wheel side mounting portions as pivot points as the kingpin shaft. is there. In addition, when two link members obtained by dividing the A-type arm member are used on the upper side or the lower side, the intersection point on the extension line of the two link members is set as a virtual pivot point, and is created outside this vehicle width direction. There is a method in which a straight line connecting a virtual pivot point and another pivot point is used as a kingpin axis. The latter method utilizes the fact that when the wheel rotates in the toe direction during turning, the intersection on the extension line becomes the instantaneous rotation center of the wheel on the upper side or the lower side.

  In any of the above methods, the pivot points on the upper side and the lower side rotate so as to draw an arc around the link (including the arm; the same applies hereinafter) on the vehicle body side. Considering the virtual upper side and lower side links by the line segment connecting the link swing axis (or link elastic center, hereinafter the same) and the pivot point at the shortest distance on the upper side and the lower side, respectively, The length, inclination, swinging direction, etc. of the link are different between the upper side and the lower side. Further, in the latter method, the link extension line intersection that becomes the virtual pivot point is easily moved in the vehicle front-rear direction during the suspension stroke. Due to these, the position and inclination of the kingpin shaft change during the suspension stroke. Due to the change of the kingpin axis, the scrub radius, caster angle and the like change.

  Usually, in order to optimize the change in the wheel alignment, the geometry of the upper side and lower side (actual) links such as length and inclination is devised. However, the locus of the pivot point on the upper side or the lower side during the suspension stroke is not controlled. That is, the above characteristics are optimized by adjusting the length and inclination of the link without adjusting the locus of the pivot point itself. For this reason, it has been difficult to simultaneously optimize the above characteristics without sacrificing some performance under various constraints such as a limited space.

  For the above problem, the suspension device of the second embodiment is adjusted in advance so that the trajectory of the virtual pivot point created inside the vehicle width direction by crossing the links when viewed from the top of the vehicle follows the trajectory of other pivot points. To do. Thereby, the change of the kingpin axis at the time of the suspension stroke is suppressed, and the wheel alignment change is reduced. This will be specifically described below.

(Kingpin axis and foil alignment)
When the steering wheel SW is steered and the tie rod 44 moves in the vehicle width direction, the axle carrier 2 (wheel W) rotates in the toe direction. On the lower side, the axle carrier 2 rotates around the lower link wheel side mounting portion 25a. Therefore, the lower link wheel side mounting portion 25a becomes the lower pivot point B.

  On the other hand, the first and second upper links 47 and 48 are crossed when the vehicle is viewed from above. Therefore, the first and second upper links 47 and 48 are in a so-called twisted position that does not intersect at one point and are not parallel to each other. The midpoint C of the line segment with the shortest distance between the first and second upper links 47 and 48 is the upper pivot point. That is, on the upper side, the point C is the instantaneous center of rotation of the axle carrier 2 in the vehicle top view. Therefore, the straight line connecting the lower pivot point B and the upper pivot point C becomes the kingpin axis L.

  As shown in FIG. 10, the angle formed by the kingpin axis L and the vertical line V in the vehicle front view is the kingpin inclination angle α, and the angle formed by the vertical line V and the wheel center line M is the (ground to ground) camber angle. β. The distance in the vehicle width direction between the point Q where the extended line of the kingpin shaft L and the ground intersect and the ground contact point P of the wheel W is the scrub radius S, and the vehicle width between the kingpin shaft L and the wheel center O Directional distance is kingpin offset R.

  Also, as shown in FIG. 11, the angle formed by the kingpin axis L and the vertical line V in the vehicle side view is the caster angle γ. The distance in the vehicle front-rear direction between the point P and the point Q is the caster trail T. The vertical line V is given by a straight line connecting the foil center O and the ground point P.

Hereinafter, the operation at the time of the suspension stroke will be described taking the case where the turning amount is zero as an example.
(Upper side pivot point setting)
As shown in FIGS. 10 to 12, the first and second upper links 47 and 48 are in a twisted position, and the length and inclination of the first and second upper links 47 and 48 are different. Therefore, during the suspension stroke, the rotation phases of the first and second upper links 47 and 48 are different, resulting in a rotation difference. That is, during the suspension stroke, the relative positional relationship (torsional relationship) between the first and second upper links 47 and 48 varies from moment to moment depending on the mounting positions on the vehicle body side and the wheel side. Therefore, the midpoint of the line segment (upper side pivot point C) at which the distance between the first and second upper links 47 and 48 is the shortest changes every moment.

  In other words, the locus drawn by the upper pivot point C at each point of the suspension stroke has an arc shape centered on the link swing shaft formed by connecting the first and second upper link vehicle body side mounting portions 47a and 48a. Must not. Instead, a predetermined trajectory is drawn according to how the first and second upper links 47 and 48 are crossed. In the second embodiment, the cross arrangement of the first and second upper links 47 and 48 (link length, inclination, mounting position) so that the trajectory of the upper pivot point C follows the trajectory of the lower pivot point B. Set.

  The tie rod 44 is connected to the axle carrier 2 on the lower side, and the tie rod 44 swings in the vehicle vertical direction together with the first and second lower links 45 and 46 during the suspension stroke. Therefore, the locus of the lower pivot point B (lower link wheel side mounting portion 25a) is an arc centered on the link swing axis formed by connecting the first and second lower link vehicle body side mounting portions 45a and 46a. It is not drawn faithfully, but is determined by the balance with the arrangement of the tie rod 44 and the bush rigidity of the first and second lower link vehicle body side mounting portions 45a and 46a.

  Therefore, after considering the locus of the lower pivot point B in advance, the kingpin shaft L formed by connecting the upper and lower pivot points B and C so as to follow this locus is the foil. The trajectory of the upper pivot point C (cross arrangement of the first and second upper links 47 and 48) is set so as to minimize the change in alignment. This setting can be performed by simulation or the like. In the following, the wheel alignment change suppressing action when set in this way will be described by taking kingpin inclination angle α, camber angle β, caster angle γ, and caster trail T as examples.

(Suppression of kingpin tilt angle change)
FIG. 13 is a view similar to FIG. 10, and the link position at the suspension stroke (bound) is indicated by a broken line. As shown in FIG. 13, the amount of displacement in the vehicle width direction of the upper pivot point C and the amount of displacement in the vehicle width direction of the lower pivot point B are substantially equal during bounding. Therefore, the kingpin axis L ′ formed by connecting the upper side pivot point C ′ and the lower side pivot point B ′ is substantially parallel to the kingpin axis L when the suspension stroke amount is zero. In other words, the difference between the kingpin inclination angle α ′ at the time of bouncing and the kingpin inclination angle α when the suspension stroke amount is zero is small, and the change of the kingpin inclination angle α is suppressed. Therefore, the vehicle width direction distance (scrub radius S) between the point Q where the extended line of the kingpin shaft L and the ground intersect and the ground contact point P of the wheel W, and the vehicle width direction distance between the kingpin shaft L and the wheel center O Changes in (Kingpin Offset R) are also suppressed.

(Suppression of camber angle change)
In general, in the front suspension, the length of the upper link is set shorter than that of the lower link from the viewpoint of layout. In the second embodiment, by crossing the first and second upper links 47 and 48, the vehicle width direction dimension of the first and second upper links 47 and 48 is kept short, and at the same time, the actual length is sufficient. To ensure. Therefore, it is possible to ensure a desired (ground-to-ground) camber characteristic while avoiding the problem that the upper side is pulled inward in the vehicle width direction than the lower side during the suspension stroke and the camber angle is greatly changed to the negative side. That is, during the suspension stroke, the change in the camber angle β is suppressed, and the size in the vehicle width direction of the first and second upper links 47 and 48 is shortened and made compact so that the space can be saved and the layout flexibility can be improved. .

  FIG. 14 is a graph showing the camber angle change during the suspension stroke in the second embodiment and the conventional example. As in the second embodiment, the conventional example is a front suspension device having links (or arms) on the lower side and the upper side, respectively. However, unlike the second embodiment, the two links are not crossed on the lower side or the upper side.

  The vertical axis in FIG. 14 indicates the suspension stroke amount, and represents a positive value when bound and a negative value when rebound. The horizontal axis represents the camber angle change amount. As shown in FIG. 14, the camber angle change amount with respect to the suspension stroke amount is large in the conventional example, whereas the camber angle change amount with respect to the suspension stroke amount is small in the second embodiment.

(Suppression of caster angle and caster trail changes)
FIG. 15 is a view similar to FIG. 11, and shows the link position and the ground at the time of the suspension stroke (bound) at the broken line. As shown in FIG. 15, at the time of bouncing, the amount of displacement of the upper pivot point C in the vehicle longitudinal direction is substantially equal to the amount of displacement of the lower pivot point B in the vehicle longitudinal direction. Therefore, the kingpin axis L ′ formed by connecting the upper side pivot point C ′ and the lower side pivot point B ′ is substantially parallel to the kingpin axis L when the suspension stroke amount is zero. In other words, the difference between the caster angle γ ′ during the suspension stroke and the caster angle γ when the suspension stroke amount is zero is small. Therefore, the change of the caster angle γ is suppressed during the suspension stroke.

  Also, during the suspension stroke, the caster trail T ′, which is the distance between the point Q ′ where the extended line of the kingpin axis L ′ intersects the ground and the wheel contact point P ′, is the caster when the suspension stroke amount is zero. It is almost the same as Trail T, and the difference is very small. Therefore, changes in the caster trail T are suppressed during the suspension stroke.

  FIG. 16 is a graph showing a change in caster trail at the time of a suspension stroke in the second embodiment and the conventional example. The conventional example of FIG. 16 is the same as the conventional example of FIG. The vertical axis in FIG. 16 indicates a caster rail, and a positive value is obtained when the intersection of the kingpin axis and the ground is positioned in front of the vehicle with respect to the ground contact point of the wheel. The horizontal axis indicates the suspension stroke amount, and represents a positive value at the time of bouncing and a negative value at the time of rebounding. As shown in FIG. 16, in the conventional example, the caster rail changes according to the change in the suspension stroke amount, whereas in the second embodiment, the caster trail is substantially constant over the entire region of the suspension stroke. The amount of change is small.

(Scuff change suppression)
In general, in the front suspension, the length of the upper link is set shorter than that of the lower link from the viewpoint of layout. In the second embodiment, the first and second upper links 47 and 48 are crossed to maintain the vehicle dimension in the vehicle width direction of the upper link at the same time, and at the same time, the vehicle width at the suspension stroke of the upper pivot point C created by crossing is used. Directional displacement is small. Therefore, the upper pivot point C is made to follow the lower pivot point B while increasing the vehicle width direction dimension of the first and second lower links 45 and 46 to suppress the scuffing change during the suspension stroke. The slope of can be made constant. Therefore, the space in the vehicle width direction of the first and second upper links 47 and 48 can be shortened and made compact while securing the steering stability, and the layout flexibility can be improved.

(Advantages of crossing)
It is also conceivable to perform control so that the intersection of the extension lines is set as a virtual pivot point without crossing the upper link and the locus is approximated to the locus of the (virtual) pivot point on the lower side. However, the displacement of the virtual pivot point with respect to the suspension stroke becomes smaller when the point where the link is crossed is used as the virtual pivot point as in the second embodiment. Therefore, the various performances (kingpin tilt angle, caster trail, etc.) resulting from the position of the virtual pivot point can be stably exhibited.

  Further, when the intersection of the extension lines is used as a virtual pivot point without crossing the link, the virtual pivot point is formed on the outer side in the vehicle width direction. At this time, the kingpin shaft is also formed on the outer side in the vehicle width direction, and the distance in the vehicle width direction (kingpin offset) between the kingpin shaft and the wheel center may be increased. In general, it is known that suspension vibration increases as this distance (kingpin offset) increases. On the other hand, when the link is crossed as in the second embodiment, the kingpin shaft can be formed on the inner side in the vehicle width direction, so the above-described problems can be solved.

  Furthermore, even if the virtual pivot point can be formed on the inner side in the vehicle width direction (with respect to the wheel center line) without crossing the link, the virtual pivot point is always on the outer side in the vehicle width direction relative to the wheel side mounting portion of the link. Will be formed. For this reason, it is difficult to tilt the upper part of the kingpin shaft sufficiently inward in the vehicle width direction while setting the kingpin offset small. In general, the upper part of the kingpin shaft is tilted inward in the vehicle width direction to generate wheel lifting torque at the time of turning to secure the restoring torque (steering response) of the steering wheel. Therefore, when the virtual pivot point is formed without crossing the link and the kingpin axis is controlled by this virtual pivot point, the kingpin offset amount (suppression of suspension vibration) and the inclination of the kingpin axis (steering response) It is difficult to achieve both optimally.

  On the other hand, when the link is crossed as in the second embodiment, the kingpin shaft L can be formed on the inner side in the vehicle width direction, so that the kingpin offset R is set while the upper portion of the kingpin shaft L is inclined toward the inner side in the vehicle width direction. There is a degree of freedom to set an appropriate value, and the above problems can be solved.

[Effect of Example 2]
Hereinafter, the effects of the suspension device 1 of the present invention that can be grasped from the second embodiment will be listed.

  (6) The first and second links that intersect in the vehicle top view are the first and second upper links 47 and 48 that are disposed on the upper side in the vehicle vertical direction with respect to the axle A.

  Since the first and second upper links 47 and 48 are crossed in this way, the dimensions in the vehicle width direction can be shortened and made compact, and at the same time, camber changes and scuff changes during the suspension stroke can be suppressed. Therefore, there is an effect that the space on the upper side can be saved while ensuring the steering stability, and the degree of freedom in layout can be improved.

  (7) A steering link for connecting the steering device on the vehicle body and the axle carrier is provided.

Therefore, when the structure which crosses a link is applied to the front suspension which has a steering function, the effect of said (1)-(4), (6) is acquired.
In addition, a virtual upper pivot point can be set by crossing the first and second links (first and second upper links 47 and 48) in the vehicle top view, and the first and second links (first and second links) during the suspension stroke can be set. The change of the upper pivot point in any side view can be controlled by the geometric change of the first and second upper links 47 and 48). Therefore, wheel alignment changes such as the kingpin inclination angle α and caster angle γ during the suspension stroke can be suppressed. Therefore, it is possible to improve the steering stability performance corresponding to various traveling situations, and to improve the steering feeling.
Further, since the displacement of the virtual pivot point formed by crossing the links is small, the above-mentioned various performances (such as the kingpin tilt angle α) due to the position of the virtual pivot point can be stably exhibited. Furthermore, by crossing the link and forming a virtual pivot point on the inner side in the vehicle width direction, both the setting of the kingpin offset amount and the setting of the kingpin tilt angle can be achieved, making it easy to suppress suspension vibration and improve steering response. It has the effect of being compatible.

  (8) The midpoint of the line segment having the shortest distance between the first and second links (first and second upper links 47 and 48) is defined as the first and second links (first and second upper links 47). , 48) is set as the rotation center (upper pivot point C) of the wheel W on the (upper) side where the wheel is provided, and this (upper) side and axle A on the opposite side (lower side) Steering rotation axis of wheel W (king pin axis L) formed by connecting the turning center of wheel W (lower pivot point B) and the above-defined rotation center of rotation (upper pivot point C). The first and second links (the first and second upper links 47 and 48) are arranged so that the inclination of) becomes constant during the suspension stroke.

  That is, in consideration of the locus of the lower side pivot point B (lower link wheel side mounting portion 25a) determined by the balance with the arrangement of the tie rods 44, the upper side pivot point C so as to follow this locus. Is set by simulation or the like. The first and second upper links are such that the inclination of the kingpin shaft L formed by connecting the pivot points B and C on the upper side and the lower side is constant during the suspension stroke, and the change in wheel alignment is minimized. 47 and 48 cross arrangements were adjusted. Therefore, the effect (7) can be obtained more efficiently.

(Other examples)
As described above, the best mode for carrying out the present invention has been described based on the first and second embodiments. However, the specific configuration of the present invention is not limited to the first and second embodiments. Design changes and the like within a range that does not depart from the gist are also included in the present invention.

  For example, in the suspension device 1 according to the first embodiment, in the rear suspension having the trailing arm, the first and second lower links 41 and 42 are crossed in the vehicle top view, but the two links to be crossed are used as the axle. It is good also as providing in the vehicle up-down direction upper side with respect to it. That is, it is possible to use one lower link and two upper links, and then cross these two upper links when viewed from the top of the vehicle. In this case, the two crossed upper links may be arranged on the front side in the vehicle front-rear direction with respect to the axle, or may be arranged on the rear side in the vehicle front-rear direction.

  In the suspension device 1 according to the second embodiment, in the front suspension that supports the steered wheels, the first and second upper links 47 and 48 are crossed as viewed from the top of the vehicle. It is good also as providing in the vehicle up-down direction lower side. That is, the first and second lower links 45 and 46 may be crossed as viewed from the top of the vehicle. In this case, during the suspension stroke, the locus of the lower pivot point created by the crossed first and second lower links 45 and 46 follows the upper pivot point so that the first and second lower links 45 and 46 follow. By setting 46, the wheel alignment change can be suppressed.

  In the suspension device 1 according to the second embodiment, the first and second upper links 47 and 48 are crossed so that the first and second upper links 47 and 48 straddle the axle A in the vehicle front-rear direction when the vehicle is viewed from above. However, similarly to the first embodiment, the first and second upper links 47 and 48 may be arranged on the front side or the rear side in the vehicle front-rear direction with respect to the axle A. In this case, the first and second lower links 45 and 46 may be arranged on the front side or the rear side opposite to the side where the first and second upper links 47 and 48 are provided and the axle A. . The same applies to the case where the first and second lower links 45, 46 are crossed as viewed from above the vehicle as described above.

1 is an overall perspective view of a suspension device according to a first embodiment. 1 is a side view of a suspension device according to a first embodiment. 1 is a front view of a suspension device according to a first embodiment. 1 is a plan view of a suspension device according to a first embodiment. 1 is a schematic plan view of a suspension device according to a first embodiment. It is a plane schematic diagram of the suspension device of the prior art (at the time of front and rear input). It is a plane schematic diagram of the suspension device of the prior art (at the time of lateral input). It is a graph which shows the relationship between the road noise in Example 1 and a prior art, and lateral rigidity. FIG. 6 is an overall perspective view of a suspension device according to a second embodiment. 6 is a front view of a suspension device according to Embodiment 2. FIG. 6 is a side view of a suspension device according to Embodiment 2. FIG. 6 is a plan view of a suspension device according to Embodiment 2. FIG. It is a front view of the suspension apparatus which concerns on Example 2 (at the time of a bound). It is a graph which shows the relationship between the suspension stroke amount in Example 2 and a prior art example, and a camber angle change. It is a side view of the suspension apparatus which concerns on Example 2 (at the time of a bound). It is a graph which shows the relationship between the suspension stroke amount in Example 2 and a prior art example, and a caster trail.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Suspension apparatus 2 Axle carrier 3 Strut 5 Trailing arm 5a Trailing arm vehicle body side attaching part 7 Steering device 7a Rack 21a First lower link wheel side attaching part 22a Second lower link wheel side attaching part 23a Upper link wheel side attaching part 25a Lower link wheel side mounting portion 26 Knuckle arm 27a First upper link wheel side mounting portion 28a Second upper link wheel side mounting portion 41 First lower link 41a First lower link vehicle body side mounting portion 42 Second lower link 42a Second Lower link vehicle body side attachment portion 43 Upper link 43a Upper link vehicle body side attachment portion 44 Tie rod 45 First lower link 45a First lower link vehicle body side attachment portion 46 Second lower link 46a Second lower link vehicle body side attachment portion 47 First upper Link 47a First upper link vehicle body side mounting portion 48 Second upper Link 48a second upper link body side mounting portion
A axle
W wheel
B Lower pivot point
C Upper pivot point
L Kingpin shaft
S Scrub radius
T Castor Trail α Kingpin Tilt β Camber Angle γ Castor Angle

Claims (8)

An axle carrier that rotatably supports the axle,
A plurality of links extending from the vehicle body side mounting portion and coupled to the axle carrier;
In a suspension device comprising:
The plurality of links are:
The vehicle has a first link and a second link that intersect with each other when viewed from the top of the vehicle, on the upper or lower side of the vehicle in the vertical direction.
A suspension apparatus comprising a third link on the upper side or the lower side opposite to the side on which the first and second links are provided and the axle. The suspension device according to claim 1,
The suspension device according to claim 1, wherein the first and second links are lower links disposed on the lower side in the vehicle vertical direction with respect to the axle. The suspension device according to claim 1,
The suspension device according to claim 1, wherein the first and second links are upper links disposed on the upper side in the vehicle vertical direction with respect to the axle.   4. The suspension device according to claim 2, wherein the first and second links are arranged on the front side or the rear side in the vehicle front-rear direction with respect to the axle. 5.   5. The suspension device according to claim 4, wherein the third link is disposed on the front side or the rear side opposite to the side on which the first and second links are provided and the axle. apparatus. The suspension device according to any one of claims 1 to 5,
The plurality of links are:
A suspension device comprising a trailing arm extending rearward of a vehicle from a vehicle body side mounting portion and connected to the axle carrier. The suspension device according to any one of claims 1 to 5,
A suspension device comprising a steering link for connecting a steering device on a vehicle body side and the axle carrier. The suspension device according to claim 7,
The midpoint of the line segment with the shortest distance between the first and second links is set as the turning center of the wheel on the side where the first and second links are provided,
A wheel formed by connecting the turning center of the wheel at the upper side or the lower side on the opposite side with respect to the axle and the set turning center of turning at the side where the first and second links are provided. The suspension apparatus according to claim 1, wherein the first and second links are arranged so that the inclination of the rotating shaft during turning is constant during the suspension stroke.

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