JPS6277207A - Rear wheel suspension device - Google Patents

Abstract

PURPOSE:To improve the performance and reduce the occupancy space of an independent suspension device of rear wheel for a passenger car by articulating a longitudinal link, respective upper and lower side lateral links to each other and a car body to constitute a square pyramid having as the apex the articulation of the longitudinal link with the car body. CONSTITUTION:The car body side articulation P0 of a longitudinal link R is disposed in the apex of a square pyramid. The longitudinal link R is articulated with the upper side lateral link U at P1 and with the lower side lateral link L at P2, and the upper and lower lateral links U, L are articulated with the car body at P3, P4 to form a supposed square pyramid having edges E1-E4. Thus, in the deformation of the square pyramid along with the upward and downward movement of wheel, the upper and lower lateral links U, L fulfill the function similar to the double wishbone and the longitudinal link R fulfills the function of trailing arm. Thus, a suspension system suited for a passenger car is provided.

Description

[Detailed description of the invention] ■1 Background of the invention 〔Technical field〕 The present invention relates to a rear wheel independent suspension system for a passenger car.

[Prior art and its problems]

BACKGROUND ART Independent left and right wheel suspension systems for passenger cars have been widely used for the front wheels, and in recent years, they have been increasingly introduced for the rear wheels as well.

Independent wheel suspension systems have lower unsprung weight than non-independent axle suspension systems, and the vertical movement of one wheel does not directly affect the wheels on the other side, resulting in improved ride comfort. It has the effect of improving road following performance. However, depending on the type and design, the distance between the ground contact points of the left and right wheels, the camber angle to the ground, and the toe angle (hereinafter collectively referred to as the ground contact characteristics) may change significantly as the vehicle body tilts left and right or moves up and down, resulting in poor maneuverability. Stability may be adversely affected. On the other hand, with an axle type, the ground contact characteristics remain virtually unchanged regardless of turning or load changes. Therefore, the independent suspension system may have worse performance than the axle type in terms of maneuverability and stability, so it is necessary to pay sufficient attention to its type and design.

The rear wheel independent suspension systems that have been put into practical use can be broadly classified into (1)
There are three types: ) single arm type, (2) parallel link type, and (3) MacPherson type (also known as strut type). A comparison of these issues focusing on the above issues is as follows.

First, (1) is subdivided into three types: swing axle, trailing arm, and semi-trailing arm, all of which have one wheel bearing or two or more wheel bearings integrated into one. They are held by an arm, and the arm rotates around a hinge-shaped fulcrum on the vehicle body side. Here, the term "hinge-like fulcrum" refers to a fulcrum whose rotational axis direction is required to be uniquely determined. The relative movement of the wheel relative to the vehicle body is thus part of a circular movement on its axis and is completely determined by the direction of the axis, the radius of the arc and the axial position of the circle of motion. The above-mentioned subdivisions differ only by the direction of this axis of motion. Therefore, the degree of freedom in design is small, and the change in the grounding characteristics described above tends to be large compared to the other two types. However, it is the most popular independent rear wheel suspension system because it has a simple structure, is inexpensive to manufacture and assemble, and occupies a small space.

A typical example of (2) is the double wishbone type, which has been popular for front wheels for a long time. The double wishbone type has a joint at both the upper and lower ends of the wheel bearing holding member (hereinafter referred to as the knuckle arm), and has a structure in which one upper and lower horizontal arm is connected to the joint, and these two arms They perform rotational movements approximately parallel to each other around each hinge-shaped fulcrum on the vehicle body side.

The axis of rotation is approximately in the longitudinal direction of the vehicle body. The motion of the wheel relative to the vehicle body is determined by connecting the wheel-side joints of two arms, each of which performs a circular motion, with a knuckle arm. Therefore, in addition to the two circular motions, there are also geometric factors related to the connection distance, which is much larger than in the case (1). As a result, there is a large degree of freedom in design (it is easy to manufacture high-performance suspension systems with thorough consideration of ground contact characteristics, and it is most widely used in racing cars. However, there are drawbacks compared to other types. , high production and installation costs due to the large number of components;
Additionally, they take up a large amount of space, which takes up space in the passenger compartment and trunk of a regular passenger car.

In addition, (3) is a type in which an elastic column is placed in the vertical direction and one arm is connected to the lower end of the column, and has a wheel bearing holding part integrated with the lower part of the column.

This type is almost equivalent to (2) in which the upper arm is extended significantly, and although the degree of freedom in design is reduced compared to (2) due to its Z flavor, it has the second best performance after (2). This is a promising format. Also, in terms of occupied space, it is almost comparable to (1). However, with this type, the external force acts as a bending force on the elastic strut that also serves as the hydraulic shock absorber, so when a large external force is applied, the strut inevitably bends slightly, and this deflection causes the hydraulic shock absorber to function normally. Frictional force other than the action is generated, which tends to cause a momentary loss of smooth operation.

From the above, as a mounting device for the rear wheels of passenger cars, types (1) and (3) are becoming popular as they are advantageous in terms of cost and occupying space, although they have problems in terms of performance. Except for two-seat sports cars, there are very few examples of its adoption.

■0 Purpose of the Invention The purpose of the present invention is to be comparable to the double Wishbone type (2) above in terms of performance, but to be comparable to the single arm type (1) and the MacPherson type (3) in terms of occupied space. (3) Disclosure of the Invention These objects are achieved by the present invention as described below.

That is, the present invention has a longitudinal link, an upper transverse link, and a lower transverse link, holds a wheel axle on the longitudinal link, and provides a first joint between the longitudinal link and the vehicle body,
Second and third joints are provided between the upper lateral link and the lower lateral link and the longitudinal link, respectively, and fourth and third joints are provided between the upper lateral link and the lower lateral link and the vehicle body, respectively. The first joint forms the apex of a square and cone, and the second, third, fourth and fifth joints form the apex of a pyramid.
The joints are located on the edges of the square pyramid, and the first, fourth, and fifth joints
The sides formed by the joints of the square pyramid are located on the car body side, and the square pyramid deforms due to changes in the angles formed by the adjacent sides of the square pyramid, thereby regulating and ensuring the movement of the wheels relative to the car body. This is a rear wheel suspension system characterized by having the following configuration.

■Specific structure of 0 invention The specific configuration of the present invention will be explained in detail below.

The @ rack device of the present invention is effective for rear wheels.

In terms of performance, it is comparable to the double-wishbone type (2), but in terms of space it occupies, it can compete with the single-arm type (1) and the MacPherson type (3), and is widely used in general passenger cars. It is possible, and in a broad sense belongs to the same category as (2). That is, both the present invention and (2) define the motion of the wheel relative to the vehicle body as "a plurality of rotatable nodes or joints,
The principle of operation is to control the deformation movement of the spatial figure formed by fixed-length members connecting the space. Specifically, the fixed length connecting member is a fixed length link and a vehicle body frame. This is hereinafter referred to as a multiple link format. Note that (1) is the rotational motion of a single member, and (3
) uses variable length connecting members.

In the present invention, the spatial figure is a square pyramid (hereinafter simply referred to as a square pyramid) without a base, and this figure is determined by five joints. Since the spatial figure formed by four nodes is a tetrahedron and cannot be deformed at all, the number of joints of five in the present invention is the minimum number of nodes that can realize the multiple link format. Incidentally, since a hinged fulcrum is equivalent to two free nodes, the number of nodes in a double wishbone is 6.
g is required at the minimum, and the formed figure is a spatial figure similar to a triangular prism, with one edge in the height direction serving as a knuckle arm, and the opposing side surface serving as the vehicle body frame.

In the rear wheel suspension system of the present invention, the members that determine the motion of the wheels relative to the vehicle body include one longitudinal link extending rearward from one fulcrum located in front of the rear wheels of the vehicle body, and These are two horizontal links that are connected to the vehicle body at a vertical distance. However, the term "vertical direction" and "horizontal direction" are rough meanings, and are not limited to exact longitudinal and lateral directions of the vehicle body. The wheel bearing is held on the longitudinal link, usually at the rear thereof, and the longitudinal position of the wheel is determined mainly by the longitudinal link, and the left and right position of the wheel is determined mainly by the two horizontal links.

FIG. 1 is a schematic diagram of the relationship between the links of the rear wheel suspension system of the present invention, viewed from the rear left of the vehicle body, and the edges E1 to E4 of the quadrangular pyramid and the wheels T are represented by broken lines. In FIG. 1, R is a vertical link that holds the bearing of the wheel shaft S, and the joint PO, which is the fulcrum on the front vehicle body side, is the apex of this square pyramid (hereinafter referred to as the apex of the square pyramid). Also, the vertical link R is the joint P1
It is connected to the upper lateral link U at the joint P2, and to the lower lateral link L at the joint P2. Joints P3 and P4 are fulcrums on the vehicle body side of the upper lateral link U and the lower lateral link L, respectively. The direction of the wheel axis S and the distance from the joint PO are determined by the holding direction and holding position X on R of the wheel bearing.

Figure 2 shows the relationship between the four sides of the square pyramid and the five joints. The side surface A1 corresponding to the longitudinal link R is POlPl and P
It is determined by the triangle made up of 2. The upper side surface A2 is determined by a triangle formed by PO, PL, and P3, and the lower side surface A3 is determined by a triangle formed by PO, P2, and P4. The remaining side A4 is determined by three points PO1P3 and P4, and each joint on this side A4, P
O2P3 and P4 are all fulcrums on the vehicle body. These 4
Since both ends of each side of the triangle are all on the same member, each side of the triangle has a fixed length.

Therefore, the shape of each triangle remains unchanged, and the apex angle of each side remains unchanged. The four half-lines E1, E2, E3, and E4 in the figure are the four edges of the square pyramid determined by Pl, P2, P3, and P4, respectively, and the vertex PO.

Relative position of the wheels to the vehicle body when stationary on a horizontal plane under rated load (
When the wheels move up and down relative to the vehicle body from the neutral position (hereinafter referred to as the neutral position), the square pyramid deforms.

The deformation consists of a set of two adjacent sides, namely Al-A2,
This is due to changes in the intersection angles of the A1-A3, A2-A4, and A3-A4 pairs (hereinafter referred to as side-adjacent angles). The factors that geometrically determine the relative motion of the wheels are: i)
4 apex angles of a square pyramid, 1i) PO position on the vehicle body, 1ii) E
3 or E4 direction on the car body, iv) Wheel axle S and PO
■) The relative position of the wheel shaft S to PO in the neutral position, vi) The position of the wheel bearing on S, and vi) The adjacent angle of each side surface in the neutral position. Of course, there are also equivalent combinations of determining factors. In addition, PO of wheel axle S
Other than the relative position with respect to the wheel and the adjacent angles of each side, everything is constant regardless of the wheel position.

These factors are determined in consideration of the ground contact characteristics, but there are various modifications to the specific structure without changing these factors. For example, regarding the position of the joint, even if each point from Pl to P4 is moved to an arbitrary position on the volumes E1 to E4, the above factors do not change at all, as shown in FIG. 2. This means that while maintaining the same functional aspects, a variety of choices can be made regarding the shape and arrangement of the link when it is installed into an actual vehicle, as will be described later.

The deformation movement of the square pyramid due to the vertical movement of the wheels is explained with reference to FIG. 3, which schematically represents the projection of the present suspension system in the longitudinal direction of the vehicle body. Figures 3a and 3C represent the states in which the wheels have moved upward and downward, respectively, relative to the vehicle body, and Figure 3b represents the neutral state. The deformation movement of the quadrangular pyramid with fixed points PO1P3 and P4 on the vehicle body is expressed by changes in the projections of edges E1 and E2. The projections of the upper lateral link U and the lower lateral link L swing as if they were the upper and lower links of a double wishbone. That is, the upper and lower lateral links U and L of the rear wheel suspension system of the present invention
Similar to the upper and lower links of a double wishbone, the wheels regulate the lateral position and camber angle of the wheels, and the rotational axes of the swing are the edges E3 and E4, which intersect at PO. In a typical double wishbone, the swing rotational axes of the upper and lower links are parallel, which corresponds to the limit when the PO is moved forward to infinity. Conversely, in the case of a double wishbone, it is also possible to consider a design in which the swing rotational axes of the upper and lower links are shifted from parallel and intersect at the front, but in that case, the link configuration would be completely different from the present invention. Regardless, they are geometrically equivalent. However, in this case too,
The drawbacks of Double Witschborn still remain.

4a, b, and c are projection views in the lateral direction of the vehicle body corresponding to FIGS. 3a, b, and c. From this direction, as shown in the figure, the behavior of the longitudinal link R is the trailing arm (1) above.
(hereinafter simply referred to as a trailing arm).

When the braking device is installed on a wheel bearing, the longitudinal external force and braking torque associated with braking are absorbed by this longitudinal link R. Therefore, the braking torque when moving forward acts in the direction of pulling up the wheels, that is, in the direction of pulling down the rear part of the car body.As with trailing arms in general, including semi-trailing arms, it has an anti-dive effect that resists sinking of the front part of the car body when braking. or demonstrated. Conversely, when braking when reversing, the rear part of the vehicle body is prevented from sinking, and in either case, it exhibits the effect of suppressing vehicle body pitching.

From the above, the rear wheel E-mount system of the present invention uses a double wishbone suspension system for regulating the lateral position and camber angle of the wheel, and a trailing arm suspension system for regulating the vertical position and behavior during braking. It has the operational advantages of both in these respects. Furthermore, three links R, U, L and five joints P, which are features of the present invention,
The mechanical rationality of the O-P4 geometric relationship, that is, the structure in which four triangles are determined by combinations of three of the five joints, has the following advantages.

The difference between the upper and lower arms of the double wishbone and the lateral links U and L of this suspension system is that in the present invention, U and L are triangular components as described above, and they do not act in the longitudinal direction against any external force. The point is that there is no need to fight against falling. Therefore, the fulcrum on the vehicle body side does not need to be hinge-shaped, and a swivel joint is sufficient. The upper and lower arms of a typical double wishbone must be either triangular with the hinge on the side of the vehicle as the bottom, or strong square with the hinges at both ends of the arm as opposite sides. The transverse link of the present invention, when it is straight and connects springs and hydraulic shock absorbers to the longitudinal link, is subject to only compressive and tension forces and does not require bending or torsional stiffness.

Of course, unlike what is shown in the drawings, it is also possible to easily adopt a shape other than a straight line for the lateral links U and L. A curved shape is also possible in order to avoid interference with a spring or a hydraulic shock absorber for convenience of installation in an actual vehicle. Compared to the bending force applied to the upper and lower links of a double wishbone during braking, the bending force due to compressive force or tension in the direction connecting both ends of the link due to the curved shape of the horizontal link is reduced in the longitudinal direction by the present invention. This is because the directional link absorbs it, so unless it is an extreme curve, it will be much smaller.

Also, the joints at both ends of the lateral links U and L, P3 and P4, and P3 and P5, respectively, may be universal joints, so if the rear wheel is a drive wheel, its drive shaft is fixed length, and the upper and lower lateral links U , L can also be used.

Similarly, the longitudinal link R of the present suspension has mechanical advantages in terms of torsional and bending loads compared to conventional trailing arms. The trailing arm has a strong hinge-shaped fulcrum on the vehicle body side for the purpose of regulating the lateral position of the wheel and the direction of the wheel axis. Therefore, a torsional load is applied between the vehicle body side fulcrum and the wheel bearing, with the longitudinal direction of the arm as the axis. Additionally, the trailing arm must absorb lateral external forces as a cantilever beam with the vehicle body side fulcrum as the support end and the wheel bearing as the load point. As a result, left and right bending loads are applied. In this suspension system, both the longitudinal link R and the lateral link U
, L are the aforementioned triangular components, so there is no need to make the vehicle body side fulcrum into a hinge shape to restrict its movement. Rather, since this fulcrum is the apex of a square pyramid, it must be flexible enough to allow rotation with a certain degree of miso spreading motion.

Specifically, rubber bushings and the like are suitable. The above-mentioned function of the fulcrum on the vehicle body side of the trailing arm is carried out by the upper and lower lateral links U and L.

Therefore, in the longitudinal link R of this suspension system, the portion to which torsional loads centered on the longitudinal direction are applied is only between the wheel bearing position X and the installation positions of the joints P1 and P2,
The working distance is smaller than the distance between the vehicle body side fulcrum of the trailing arm and the wheel bearing, and the required torsional rigidity can be provided with a smaller cross-sectional area. Further, as a matter of course, if the joints P1 and P2 with the lateral links U and L are located substantially above and below the wheel bearing position X, this torsional load becomes so small that it can be substantially ignored.

The same applies to the left and right bending of the longitudinal link R along the length direction due to a lateral external force. That is, the joints P1 and P2 with the lateral links U and L above and below the wheel bearing position
is located, the bending loads are virtually negligible.

The connection MPI and P2 with the lateral links U and L are at the wheel bearing position W
Not located above or below x, but between the vehicle body side fulcrum PO and the wheel bearing position
If the longitudinal link R is located in the middle of ), and a bending load is applied. Further, when the joints P1 and P2 with the lateral links U and L are located behind the wheel bearing position X, the lateral links U,
The lateral concentrated load is stopped at the wheel bearing position X by using the positions of the joints P1 and P2 with L and the fulcrum PO on the vehicle body side as support points at both ends.

However, even in these cases, it is still more advantageous than the trailing arm in terms of left and right bending. It is a cantilever beam whose supporting end is the fulcrum on the car body side (
t for the trailing arm that stops the Uke as a
This is due to the structural mechanical rationality of the longitudinal link R of the present invention, which is supported as an ail end support beam. Comparisons between these two types of beams are well known, and therefore, the longitudinal link R of the present invention requires less bending rigidity than the trailing arm. Of course,
If the joints PI and P2 with the lateral links U and L are located extremely forward and close to the PO, this advantage will be lost.

The reaction force when a spring and hydraulic shock absorber are connected to this vertical link R, and the vertical bending load associated with the braking torque act in substantially the same manner as in the case of the trailing arm. Because the stress caused by the latter decreases toward the fulcrum on the vehicle body side, the parts of the longitudinal link R of this suspension system that require particular strength and rigidity are
Considering the above, the joint P1 with the upper and lower lateral links U and L,
Only between P2 and wheel bearing position X, and near the connecting portion when the spring and hydraulic shock absorber are connected.

Above, we compared the external force burden on the arms and links that make up the suspension system, but at the same time, the burden on the vehicle body frame also
Generally requires less compared to a double wishbone or trailing arm. The reason for this is that in both of these cases, the external force must be absorbed intensively at the hinge-shaped fulcrum on the vehicle body frame, whereas in the present invention, the hinge-shaped fulcrum is unnecessary as described above, and the stress concentration in the vehicle body frame is reduced. Because it can be avoided.

The fact that the load on the links and the vehicle body frame is small in this way means that the present suspension system can be easily deformed for installation purposes in terms of material mechanics. Figure 5
is a view of Figure 1 viewed from diagonally above the rear of the vehicle.
FIG. 6 is an example in which the upper and lower lateral links U and L are connected in front of the wheel axis S, and the distance between the joints in FIG. 5 is similarly reduced. The upper and lower lateral links U and L of this suspension system do not necessarily need to be located above and below the wheel axis S, unlike the upper and lower links of a double wishbone. Therefore, the degree of freedom of installation and arrangement is much higher than that of the double wishbone. At the same time, the space occupied by the lateral links U and L has also been reduced. When the distance between joints is similarly reduced using double wishbones, the locus of the vertical movement of the wheel is also similarly reduced, and as a result, the range of vertical movement of the wheel (hereinafter referred to as stroke) is reduced.
will decrease at the same rate. In FIG. 6, the distance between PO and S is the same as in FIG. 5, so the vertical trajectory of the wheel is completely the same as in FIG. 5, and the stroke does not decrease at all. Only the dimensions and movements of the lateral links have been reduced.

FIG. 7 shows a modification in which the vertical link R of FIG. 6 is bent, in other words, the wheels T are moved inward on S, thereby further reducing the occupied space. Expressing this in reverse, the wheel T
This is equivalent to moving the square pyramid outward without changing its position, and is made possible by the forward placement of the lateral links. wheel T
6 is closer to the fixed side surface A4, the stroke is the same as in FIG. 6 and has not decreased. In a double wishbone, a reduction in the distance between the wheel and the fulcrum of the upper and lower arms means a reduction in the distance between the joints, which necessarily accompanies a reduction in the stroke as described above.

FIG. 8 shows an example in which the lateral links U and L are arranged on the same side of the longitudinal link R as the wheel T. A1 is moved to the inside of the vehicle body, A4, which is fixed to the vehicle body side, is moved to the outside, and the wheel T is located between the two. If one of the lateral links U and L were placed on the outside and the other on the inside, this would greatly deviate from the working geometry of the present suspension system, which is a deformation of a square pyramid with the side apex angle kept constant, and this would be contrary to the present invention. will have a different format. This constitutes a kind of Watt link, and is an unfavorable arrangement in which the camber angle changes greatly as the wheel moves up and down.

Regarding the springs and hydraulic shock absorbers connected to this suspension system, there are no special restrictions on their types, connection positions, and methods, and there is no major difference from conventional suspension systems. The members connecting the spring and hydraulic shock absorber are three links R, U,
Either L may be used, and both may be connected at the same position, or may be connected at different positions or to separate members. When using an integrated coil damper unit, they are necessarily in the same position, and when using a torsion bar or leaf spring as the spring, they are necessarily at different positions. In any case, in response to these reaction forces, as with conventional throat rack devices,
The closer the connection position is to the wheel bearing, the more advantageous it is in terms of material mechanics. From this point of view, the longitudinal link R holding the wheel bearing is
It is desirable to connect to

FIG. 9 is a special example in which a single wooden flexible bar member is used as the left and right lower lateral force direction links U, and serves both the functions of a spring and a link. A similar example also exists in Double Wishbone, in which the flexible rod has a means for determining only its position in the longitudinal direction, that is, in the left and right direction of the vehicle body, and the flexible rod is fixed at two intermediate left and right points P.
4. It is supported by the vehicle body at P4. As a means of supporting this,
Use means that does not fix the angle of the rod with the vehicle body at its supporting position. In that case, the bending of the flexible rod due to the vertical movement of one wheel will act to cause a movement in the same direction on the other wheel, and this rod will act as a link between the transverse links, the body support springs and the stabilizer to counter roll. It has a combination of different functions.

Regarding the shape of the vertical link R, the contour of its horizontal projection is not limited to a triangle. Above is P
For convenience of clearly indicating the arrangement of O, PL and P2,
We have explained the shape of a triangle with these as vertices, or a triangle bent from a plane. As long as the shape can ensure the vertical distance between Pl and P2 and the distance between PO, Pl, and P2, there can be various modifications taking into consideration the vehicle body structure and stress distribution. Figure 10 shows the part R1 that connects PI and R2, similar to the knuckle arm of a double wishbone.
This is an example of an L-shaped shape in which a rod-shaped trailing link portion R2 having a slight taper and connecting PO-R1 is integrated. As mentioned above, the braking torque is applied to the vertical and horizontal links U.
, since it is not input to L, the part R similar to the knuckle arm
No braking torque is applied to 1, but is applied to the rod-shaped portion R2 connected to the vehicle body at PO. Note that this figure shows a case where the coil spring B and the hydraulic shock absorber C are connected to the vertical link at different positions.

When Pl and P2 are arranged in front of the wheel axle S as shown in FIG. 6, the shape of the longitudinal link R is generally a rhombus or a bar having projections for installing Pl and P2. FIG. 11 shows an example of the shape of the longitudinal link R when Pl is moved forward from FIG. 10 and P2 is left at the same position as in FIG. ing.

FIG. 12a shows an example of a shape in which Pl and P2 are installed outside the center line of the vertical link R instead of bending in order to achieve the same effect as the bending of the vertical link R in FIG. In other words, the vertical link R is shaped like a bar that is substantially parallel to the front-back direction of the grass body, and a protrusion R3 is provided on the longitudinal link R.
The upper and lower horizontal links U and L are connected to each other. The shape of this protrusion R3 and the state of connection with the vertical and lateral links U and L are shown in FIG. 12b when viewed from the rear of the vehicle body. To avoid interference with the vertical link due to vertical movement, the horizontal link U
, L are given a slight curvature in the vertical direction.

In this suspension system, since none of the joints need to be hinge-shaped, the positions of all the joints can be adjusted in any direction, front, back, left, right, up and down, even after being assembled into the vehicle body. Therefore, the toe angle can be adjusted by moving the fulcrum PO of the longitudinal link on the vehicle body to the left and right. This is almost equivalent to rotating a square pyramid about its vertical axis by moving its apex, and as a result, the direction of the wheel axis S changes. P.O.
The left and right movement of the toe angle is possible not only during installation and maintenance, but also while driving, and actively changing the toe angle improves maneuverability and stability to some extent during turns and sudden braking. be able to. In order to enable PO to move left and right while running, ■ use a fulcrum with large compliance in the direction of the rotation axis, ■ use a fulcrum with a composite structure that can move left and right, ■ install a fulcrum on the sliding axis, etc. are considered, and the movement range increases in this order. These are selected according to design intent and used in combination with positive control means for PO left and right positions.

As a method for regulating the left and right positions, there are an active method using a hydraulic cylinder or the like, or a passive method using an auxiliary link or the like. In the case of active operation, acceleration, front wheel steering angle, and vehicle speed are measured and calculated by electronic means, and power is used to move the PO so that it is always at the optimum position. In the case (2) above, it is also possible to use the hydraulic cylinder itself as the sliding axis. The passive method is a method that utilizes the bending and stretching of the suspension system due to changes in the posture of the vehicle body relative to the ground. FIG. 13 shows the structural example of the above (2) and the relationship between the vertical link R and the auxiliary arm link, and the PO has a structure in which a rubber bush 2 is provided on a shackle 1 that can swing from side to side. Auxiliary link 3 connecting the vehicle body and longitudinal link R
When installed with an upward slope toward the inside, when the vertical link R swings upward, the auxiliary link 3
is moved outward, and the toe angle changes in the toe-out direction.

Conversely, when the vertical link R swings downward, the PO is moved inward, and the toe angle changes in the toe-in direction.

This behavior is regardless of the fulcrum structure of the PO (and the same applies to the above).

The relationship between the amount of left-right movement of PO and the amount of change in toe angle differs not only depending on the length of each link R, U, and L but also on their arrangement. For example, if the A1 side of a square pyramid is placed parallel to the longitudinal direction of the vehicle body, and the lateral links tJ and L are connected perpendicular to A1 almost above and below the wheel axis S, in order to change the toe angle by 1 degree, The necessary horizontal movement amount of PO is: When the distance between PO and wheel shaft S is 600 fl, approximately 10 m, 70
At 0u, it is about 12fl.

In addition, if P3 and P4 are fixed and PO is moved independently, the side apex angle of the square pyramid will change slightly except for the A1 side, and depending on the arrangement of the lateral links, the left and right positions of the wheels and the camber angle will change slightly. Care must be taken, as the impact on

For example, as shown in Figs. 6 and 7, when the lateral link is placed in the front, it affects the left and right position of the wheel, and in the case as shown in Fig. 11, where the front and back positions of the upper and lower links are significantly different, the camber It also affects the corners.

Therefore, taking these influences into consideration, the above 1) to vii
) design factors need to be determined.

■1 Specific Effects of the Invention As detailed above, the rear wheel suspension system of the present invention is comparable to the double-witshbone type in terms of performance, while competing with the single-arm type and MacPherson type in terms of occupied space. I can,
- Can be used extensively for marine vehicles.

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining the present invention in detail, and FIG. 2 is a perspective view for explaining the positional relationship of joints constituting the present invention. 3a, 3b, and 30 are front views in the longitudinal direction of the vehicle body, respectively, showing the effect of the present invention, and FIG.
2, Figures 4b and 40 are side views of Figures 3a, 3b and 3c, respectively. 5, 6, 7, and 8 are perspective views for explaining different embodiments of the present invention, and 3 is a perspective view showing the embodiment of the present invention. PO, Pi, P2, P3, P4... Joints A1, A
2, A3, A4... Square pyramid side E1, E2, E3
, E4... Square pile R... Vertical link U... Upper lateral link L... Lower lateral link S... Wheel axle, T... Wheel Fig, I Fig, 2 Fig , 5 Ftg, 6F
ig, 7 Fig, 8Ftg
, 9 Fig, 10 Fig, 11 Fig, 12a Fig, 1
2big13

Claims (7)

[Claims] (1) It has a longitudinal link, an upper lateral link, and a lower lateral link, the wheel axle is held on the longitudinal link, a first joint is provided between the longitudinal link and the vehicle body, and the upper lateral Second and third joints are provided between the directional link and the lower lateral link and the longitudinal link, respectively, and fourth and fifth joints are provided between the upper lateral link and the lower lateral link and the vehicle body, respectively. joints are provided, the first joint forms the apex of the square pyramid, the second, third, fourth and fifth joints are located on each edge of the square pyramid; The side surface formed by the joint is located on the vehicle body side, and the square pyramid is deformed by changing the angle formed by each adjacent side surface of the square pyramid, thereby regulating and ensuring the movement of the wheels relative to the vehicle body. A rear wheel suspension system characterized by comprising: (2) The rear wheel suspension system according to claim 1, wherein the first joint is located forward of the vehicle body from the wheel axle. (3) The rear wheel suspension system according to claim 1 or 2, wherein the wheel axle is located within the side surface of a square pyramid determined by the first, second, and third joints. (4) The rear wheel suspension system according to claim 1 or 2, wherein the wheel axle is located further rearward of the vehicle body than the second and/or third joints. (5) A patent claim in which the longitudinal link is formed by integrating a portion that connects the first joint and the second or third joint, and a portion that connects the second joint and the third joint. A rear wheel suspension system according to any one of items 1 to 4. (6) The rear wheel suspension system according to any one of claims 1 to 5, wherein the wheel axle holding portion of the longitudinal link is located on the outer side of the vehicle body than the second and third joints. (7) A rear wheel suspension system according to any one of claims 1 to 6, wherein the first joint is movably provided on the vehicle body.