JP5510370B2 - Automobile - Google Patents

Description

The present invention relates to an automobile provided with a vehicle suspension device for suspending a vehicle body.

Conventionally, in a suspension device for a vehicle, a desired suspension performance is achieved by setting a kingpin shaft.
For example, in the technique described in Patent Document 1, the operability and stability are improved by adopting a link arrangement that suppresses movement in the vehicle front-rear direction at the time of turning of the upper and lower pivot points constituting the king pin.

JP 2010-126041 A

However, when steering is performed while the vehicle is traveling, the lateral force corresponding to the traveling speed is input to the tire ground contact point. However, the technique described in Patent Document 1 does not consider the influence of the lateral force. Therefore, there is room for improvement in reducing the moment generated around the kingpin axis during turning. In other words, the conventional vehicle suspension apparatus has room for improvement in terms of improving maneuverability and stability.
The subject of this invention is improving the controllability and stability of the suspension apparatus for vehicles.

In order to solve the above problems, an automobile according to the present invention includes a control / drive circuit unit that operates an actuator according to a steering state of a steering wheel to steer a steered wheel, and a suspension that supports the steered wheel on a vehicle body. Device.
The suspension device is arranged such that a first link member and a second link member that connect the wheel hub mechanism and the vehicle body are crossed in a top view of the vehicle below the axle in the vehicle vertical direction.
In addition, a vertical line drawn down from a grounding point of the kingpin shaft having the intersection of the first link member and the second link member as viewed from the top of the vehicle to the lower pivot point and passing through the tire grounding center in the direction of the side slip angle of the tire. The foot position was set to be within the tire ground contact surface.
The control / drive circuit unit operates the actuator to generate a restoring force for self-alignment on the steered wheels, thereby steering the steered wheels and ensuring straightness of the vehicle.

According to the present invention, the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction, so that the moment around the kingpin axis can be further reduced.
Therefore, the steering can be performed with a smaller rack axial force, and the direction of the wheel can be controlled with a smaller force.
Therefore, maneuverability and stability can be improved.

1 is a schematic diagram illustrating a configuration of an automobile 1 according to a first embodiment. It is a perspective view which shows typically the structure of the suspension apparatus 1B. It is a top view which shows typically the structure of the suspension apparatus 1B. It is the partial front view and partial side view which show typically the structure of the suspension apparatus 1B. It is a figure which shows the relationship between the rack stroke at the time of steering, and a rack axial force. It is a figure which shows the locus | trajectory of the tire ground-contact surface center at the time of steering. FIG. 5 is an isoline diagram showing an example of rack axial force distribution at coordinates with a kingpin tilt angle and a scrub radius as axes. It is a schematic diagram which shows the example which comprised the suspension apparatus 1B by the compression type suspension apparatus. It is a figure which shows the relationship between the toe angle and the scrub radius in the case of the compression-type suspension apparatus in which the lower link members do not intersect and the present invention. It is a conceptual diagram explaining the self-aligning torque at the time of setting it as a positive scrub. It is a figure which shows typically the relationship between a kingpin inclination | tilt angle and a scrub radius. It is a figure which shows the structural example which applied this invention to the suspension apparatus which has a knuckle. It is a schematic diagram which shows the example which comprised the suspension apparatus 1B with the tension type suspension apparatus.

Embodiments of an automobile to which the present invention is applied will be described below with reference to the drawings.
(First embodiment)
(Constitution)
FIG. 1 is a schematic diagram showing a configuration of an automobile 1 according to the first embodiment of the present invention.
In FIG. 1, an automobile 1 includes a vehicle body 1A, a steering wheel 2, an input side steering shaft 3, a steering wheel angle sensor 4, a steering torque sensor 5, a steering reaction force actuator 6, and a steering reaction force actuator angle sensor 7. A steering actuator 8, a steering actuator angle sensor 9, an output side steering shaft 10, a steering torque sensor 11, a pinion gear 12, a pinion angle sensor 13, a steering rack member 14, and a tie rod 15 The tie rod axial force sensor 16, the wheels 17FR, 17FL, 17RR, 17RL, the brake disc 18, the wheel cylinder 19, the pressure control unit 20, the vehicle state parameter acquisition unit 21, and the wheel speed sensors 24FR, 24FL, 24RR. 24RL and control / drive circuit unit And 26, and a mechanical backup 27.

The steering wheel 2 is configured to rotate integrally with the input side steering shaft 3, and transmits a steering input by the driver to the input side steering shaft 3.
The input-side steering shaft 3 includes a steering reaction force actuator 6, and applies a steering reaction force by the steering reaction force actuator 6 to the steering input input from the steering wheel 2.

The steering wheel angle sensor 4 is provided on the input side steering shaft 3 and detects the rotation angle of the input side steering shaft 3 (that is, the steering input angle to the steering wheel 2 by the driver). Then, the handle angle sensor 4 outputs the detected rotation angle of the input side steering shaft 3 to the control / drive circuit unit 26.
The steering torque sensor 5 is installed on the input side steering shaft 3 and detects the rotational torque of the input side steering shaft 3 (that is, the steering input torque to the steering wheel 2). Then, the steering torque sensor 5 outputs the detected rotational torque of the input side steering shaft 3 to the control / drive circuit unit 26.

In the steering reaction force actuator 6, a gear that rotates integrally with the motor shaft meshes with a gear formed in a part of the input-side steering shaft 3, and input by the steering wheel 2 in accordance with an instruction from the control / drive circuit unit 26. A reaction force is applied to the rotation of the side steering shaft 3.
The steering reaction force actuator angle sensor 7 detects the rotation angle of the steering reaction force actuator 6 (that is, the rotation angle by the steering input transmitted to the steering reaction force actuator 6), and sends the detected rotation angle to the control / drive circuit unit 26. Output.

The steered actuator 8 has a gear that rotates integrally with the motor shaft meshes with a gear formed on a part of the output side steering shaft 10, and the output side steering shaft 10 is moved according to an instruction from the control / drive circuit unit 26. Rotate.
The steering actuator angle sensor 9 detects the rotation angle of the steering actuator 8 (that is, the rotation angle output by the steering actuator 8) and outputs the detected rotation angle to the control / drive circuit unit 26. To do.

The output side steering shaft 10 includes a steering actuator 8, and transmits the rotation input by the steering actuator 8 to the pinion gear 12.
The steering torque sensor 11 is installed on the output side steering shaft 10 and detects the rotational torque of the output side steering shaft 10 (that is, the steering torque of the wheels 17FR and 17FL via the steering rack member 14). Then, the steering torque sensor 11 outputs the detected rotational torque of the output side steering shaft 10 to the control / drive circuit unit 26.

The pinion gear 12 meshes with a spur tooth formed on the steering rack member 14 and transmits the rotation input from the output side steering shaft 10 to the steering rack member 14.
The pinion angle sensor 13 detects the rotation angle of the pinion gear 12 (that is, the turning angle of the wheels 17FR and 17FL output via the steering rack member 14), and controls / drives the detected rotation angle of the pinion gear 12. Output to the circuit unit 26.

The steering rack member 14 has spur teeth that mesh with the pinion gear 12, and converts the rotation of the pinion gear 12 into a linear motion in the vehicle width direction. In the present embodiment, the steering rack member 14 is located on the vehicle front side with respect to the front wheel axle.
The tie rod 15 connects both ends of the steering rack member 14 and the knuckle arms of the wheels 17FR and 17FL via ball joints.

The tie rod axial force sensor 16 is installed in each of the tie rods 15 installed at both ends of the steering rack member 14 and detects the axial force acting on the tie rod 15. The tie rod axial force sensor 16 outputs the detected axial force of the tie rod 15 to the control / drive circuit unit 26.
The wheels 17FR, 17FL, 17RR, and 17RL are configured by attaching tires to tire wheels, and are installed on the vehicle body 1A via the suspension device 1B. Among these, for the front wheels (wheels 17FR and 17FL), the direction of the wheels 17FR and 17FL with respect to the vehicle body 1A changes as the knuckle arm swings with the tie rod 15.

The brake disk 18 rotates integrally with the wheels 17FR, 17FL, 17RR, and 17RL, and when the pressing force of the wheel cylinder 19 presses against the brake pad, a braking force is generated by the frictional force.
The wheel cylinder 19 generates a pressing force that presses a brake pad installed on each wheel against the brake disc 18.

The pressure control unit 20 controls the pressure of the wheel cylinder 19 installed on each wheel in accordance with an instruction from the control / drive circuit unit 26.
The vehicle state parameter acquisition unit 21 acquires the vehicle speed based on a pulse signal indicating the rotation speed of the wheels output from the wheel speed sensors 24FR, 24FL, 24RR, 24RL. Moreover, the vehicle state parameter acquisition part 21 acquires the slip ratio of each wheel based on the vehicle speed and the rotational speed of each wheel. Then, the vehicle state parameter acquisition unit 21 outputs the acquired parameters to the control / drive circuit unit 26.

The wheel speed sensors 24FR, 24FL, 24RR, 24RL output a pulse signal indicating the rotational speed of each wheel to the vehicle state parameter acquisition unit 21 and the control / drive circuit unit 26.
The control / driving circuit unit 26 controls the entire automobile 1, and based on signals input from sensors installed in each part, the steering reaction force of the input side steering shaft 3, the steering angle of the front wheels, or the mechanical backup 27, various control signals are output to the steering reaction force actuator 6, the steering actuator 8, the mechanical backup 27, or the like.

  Further, the control / drive circuit unit 26 converts the detection value by each sensor into a value corresponding to the purpose of use. For example, the control / drive circuit unit 26 converts the rotation angle detected by the steering reaction force actuator angle sensor 7 into a steering input angle, or converts the rotation angle detected by the steering actuator angle sensor 9 into the wheel turning angle. Or the rotation angle of the pinion gear 12 detected by the pinion angle sensor 13 is converted into the turning angle of the wheel.

  Note that the control / drive circuit unit 26 includes a rotation angle of the input side steering shaft 3 detected by the steering wheel angle sensor 4, a rotation angle of the steering reaction force actuator 6 detected by the steering reaction force actuator angle sensor 7, and a steering actuator. The rotation angle of the steering actuator 8 detected by the angle sensor 9 and the rotation angle of the pinion gear 12 detected by the pinion angle sensor 13 are monitored, and the occurrence of a failure in the steering system is detected based on these relationships. can do. When a failure in the steering system is detected, the control / drive circuit unit 26 outputs an instruction signal for connecting the input side steering shaft 3 and the output side steering shaft 10 to the mechanical backup 27.

The mechanical backup 27 connects the input side steering shaft 3 and the output side steering shaft 10 in accordance with instructions from the control / drive circuit unit 26, and ensures transmission of force from the input side steering shaft 3 to the output side steering shaft 10. Mechanism. Here, the control / drive circuit unit 26 normally instructs the mechanical backup 27 not to connect the input side steering shaft 3 and the output side steering shaft 10. When the steering system needs to perform a steering operation without passing through the steering wheel angle sensor 4, the steering torque sensor 5, the steering actuator 8, and the like due to the occurrence of a failure, the input side steering shaft 3 and the output side steering shaft 10 is input.
The mechanical backup 27 can be configured by, for example, a cable type steering mechanism.

FIG. 2 is a perspective view schematically showing the configuration of the suspension device 1B according to the first embodiment. FIG. 3 is a plan view schematically showing the configuration of the suspension device 1B of FIG. FIG. 4 is a (a) partial front view and (b) partial side view schematically showing the configuration of the suspension device 1B of FIG.
As shown in FIGS. 2 to 4, the suspension device 1 </ b> B is an axle carrier that has wheels 17 FR and 17 FL attached to a wheel hub, and has an axle 32 that rotatably supports the wheels 17 FR and 17 FL. 33, a plurality of link members arranged in the vehicle body width direction from the support portion on the vehicle body side and connected to the axle carrier 33, and a spring member 34 such as a coil spring.

  The plurality of link members include a first link (first link member) 37 and a second link (second link member) 38, a tie rod (tie rod member) 15, and a strut (spring member 34 and It is composed of a shock absorber 40). In the present embodiment, the suspension device 1B is a strut type suspension, and the upper end of the strut in which the spring member 34 and the shock absorber 40 are integrated is connected to a support portion on the vehicle body side that is located above the axle 32 (hereinafter referred to as “the suspension member 1B”). The upper end of the strut is appropriately referred to as an “upper pivot point”).

  The first link 37 and the second link 38 constituting the lower link connect the lower end of the axle carrier 33 and the support portion on the vehicle body side located below the axle 32. In the present embodiment, the first link 37 and the second link 38 are I arms made of independent members. The first link 37 and the second link 38 are connected to the vehicle body side by one support portion, and are connected to the axle 32 side by one attachment portion. Further, the first link 37 and the second link 38 in the present embodiment connect the vehicle body 1A and the axle 32 side (axle carrier 33) in a state of crossing each other (hereinafter, the first link 37 and the second link 38). The intersections of the virtual links formed by and are appropriately referred to as “lower pivot points”).

  The tie rod 15 is positioned below the axle 32 and connects the steering rack member 14 and the axle carrier 33. The steering rack member 14 transmits the rotational force (steering force) input from the steering wheel 2 to steer. Generate axial force for Accordingly, the tie rod 15 applies an axial force in the vehicle width direction to the axle carrier 33 in accordance with the rotation of the steering wheel 2, and the wheels 17FR and 17FL are steered through the axle carrier 33.

  In the present invention, the king pin shaft of the suspension device 1B is set so that the caster trail is positioned within the tire ground contact surface. More specifically, in the suspension device 1B in the present embodiment, the caster angle is set to a value close to zero, and the kingpin axis is set so that the caster trail approaches zero. Thereby, the tire twisting torque at the time of turning can be reduced, and the moment around the kingpin axis can be further reduced. The scrub radius is a positive scrub with zero or more. Thereby, since the caster trail corresponding to the scrub radius is generated with respect to the tire skid angle at the time of turning, straight running performance can be ensured.

  In the present invention, the first link 37 and the second link 38, which are lower link members, connect the vehicle body 1A and the axle 32 side (the lower end of the axle carrier 33) in a state of crossing each other. Thereby, compared with the structure where the 1st link 37 and the 2nd link 38 do not cross, a kingpin inclination angle can be made small and a scrub radius can be enlarged to the positive scrub side. Therefore, the tire twisting torque at the time of turning can be reduced, and the rack axial force required for turning can be reduced. Furthermore, in the present invention, since the virtual lower pivot point moves to the inside of the vehicle body due to the lateral force acting on the wheel at the time of turning, it is possible to improve the straightness by the self-aligning torque (SAT).

Hereinafter, the suspension geometry in the suspension device 1B will be examined in detail.
(Analysis of rack axial force component)
FIG. 5 is a diagram illustrating the relationship between the rack stroke and the rack axial force during steering.
As shown in FIG. 5, the rack axial force component mainly includes a tire twisting torque and a wheel lifting torque, and of these, the tire twisting torque is dominant.
Therefore, the rack axial force can be reduced by reducing the torsional torque of the tire.

(Minimizing tire twisting torque)
FIG. 6 is a diagram illustrating a trajectory of the center of the tire ground contact surface at the time of turning.
In FIG. 6, the case where the amount of movement of the center of the tire contact surface at the time of turning is large and the case where it is small are shown together.
From the analysis result of the rack axial force component, in order to reduce the rack axial force, it is effective to minimize the tire twisting torque at the time of turning.
In order to minimize the tire twisting torque at the time of turning, as shown in FIG. 6, the locus at the center of the tire contact surface may be made smaller.
That is, the tire torsion torque can be minimized by matching the center of the tire contact surface with the kingpin contact point.
Specifically, it is effective to set the caster trail to 0 mm and the scrub radius to 0 mm or more.

(Effect of kingpin tilt angle)
FIG. 7 is an isoline diagram showing an example of rack axial force distribution at coordinates with the kingpin tilt angle and scrub radius as axes.
In FIG. 7, an isoline in the case where the rack axial force is small, medium and large is shown as an example.
As the kingpin tilt angle increases with respect to tire torsion torque input, the rotational moment increases and the rack axial force increases. Therefore, it is desirable to set the kingpin tilt angle to be smaller than a certain value, but from the relationship with the scrub radius, for example, if the kingpin tilt angle is 15 degrees or less, the rack axial force can be reduced to a desired level.

  7 is smaller than a kingpin inclination angle of 15 degrees at which the lateral force can be estimated to exceed the friction limit in the turning limit region, and the viewpoint of the tire twisting torque. Thus, an area having a scrub radius of 0 mm or more is shown. In the present embodiment, this region (the direction in which the kingpin tilt angle decreases from 15 degrees on the horizontal axis and the direction in which the scrub radius increases from zero on the vertical axis) is a region that is more suitable for setting. However, even if the scrub radius is a negative region, a certain effect can be obtained by indicating other conditions in this embodiment.

  Specifically, when determining the scrub radius and the kingpin tilt angle, for example, the isoline indicating the rack axial force distribution shown in FIG. 7 is approximated as an nth-order curve (n is an integer of 2 or more), A value determined by the position of the inflection point (or peak value) of the n-th order curve from the region surrounded by the chain line can be adopted.

(Specific configuration example)
Next, a specific configuration example for realizing the suspension device 1B will be described.
FIG. 8 is a schematic diagram showing an example in which the suspension device 1B is configured by a compression type (a type in which each lower link member is located on the vehicle rear side from the axle in a top view of the vehicle).
That is, in the example shown in FIG. 8, the tension rod (first link 37) is connected to the vehicle body at a position where the tension rod (first link 37) extends along the axle and the compression rod (second link 38) extends rearward from the axle when viewed from above the vehicle.

  As shown in FIG. 8, in the compression type suspension device, when a double pivot system is used in which the lower link members intersect each other, each lower link member turns by rotating forward of the vehicle around the vehicle body side support point. Steering as an outer wheel is possible (in a broken line state). At this time, the virtual lower pivot point is the point where the lower link member intersects, but since the virtual lower pivot point can be formed inside the vehicle body rather than the suspension type where the lower link member does not intersect, the initial scrub radius is set in the positive scrub direction. Can be big.

  In the compression type suspension device shown in FIG. 8, the rotation angle of the compression rod at the time of turning is large, so the virtual lower pivot point moves to the inside of the vehicle body. In this case, when viewed from the top of the vehicle, the distance from the tire center line to the virtual lower pivot point in the front-rear direction of the tire moves inward of the vehicle body from the tire center line, so the scrub radius increases in the positive scrub direction. Therefore, in the compression-type suspension device, when the present invention is applied, the rack axial force is reduced by turning as a turning outer wheel.

  Incidentally, in the case of a compression-type suspension device in which the lower link members do not intersect, the rotation angle of the compression rod at the time of turning is large, so the virtual lower pivot point moves to the outside of the vehicle body. In this case, since the distance from the tire center line to the virtual pivot point in the tire front-rear direction in the vehicle top view is located on the vehicle outer side than the tire center line, the scrub radius increases in the negative scrub direction. Therefore, the rack axial force is increased by performing the steering.

In the example shown in FIG. 8, the wheel center moves to the inside of the turn when turning in the vehicle top view. Therefore, the effect of reducing the rack axial force can be further enhanced by positioning the rack shaft 14 in front of the axle as in the present embodiment.
FIG. 9 is a view showing the relationship between the toe angle and the scrub radius in the case of the compression type suspension device in which the lower link members do not intersect and the present invention.
As shown in FIG. 9, in the case of the present invention, the scrub radius in the vicinity of the neutral position (toe angle is 0) can be made larger than in the case where the lower link members are not crossed. Moreover, in the direction (the minus direction in FIG. 9) in which the turning angle that becomes the turning outer wheel becomes large, the scrub radius becomes larger and the rack axial force can be made smaller.

(Ensuring straightness by positive scrub)
FIG. 10 is a conceptual diagram for explaining the self-aligning torque in the case of a positive scrub.
As shown in FIG. 10, the restoring force (self-aligning torque) acting on the tire increases in proportion to the sum of the caster trail and the pneumatic trail.
Here, in the case of positive scrubbing, the distance εc from the wheel center (see FIG. 10) determined by the position of the foot of the vertical line that is lowered from the grounding point of the kingpin shaft to the straight line in the direction of the side slip angle β of the tire passing through the tire grounding center. It can be regarded as a caster trail.

Therefore, the greater the scrub radius of the positive scrub, the greater the restoring force acting on the tire during turning.
In this embodiment, the setting of the kingpin axis is a positive scrub and the initial scrub radius can be secured larger than when the lower link member is not crossed, so that the effect on the straightness by bringing the caster angle closer to 0 is achieved. Is reduced. In addition, since the steer-by-wire system is adopted, it is possible to ensure the final straightness by the steered actuator 8.

(Function)
Next, the operation of the suspension device 1B according to this embodiment will be described.
In the suspension device 1B according to the present embodiment, the two lower link members are I-arms. The compression rod is installed along the vehicle width direction from the axle carrier 33, and the tension rod is installed obliquely from the lower end of the axle carrier 33 to the vehicle rear side in a state of intersecting the compression rod.
At this time, a straight line connecting the support point on the vehicle body 1A side and the support point on the axle 32 side is assumed for each lower link member. Then, the intersection of these straight lines becomes the lower link virtual lower pivot point. A straight line connecting the virtual lower pivot point and the upper pivot point formed by the upper end of the strut is a kingpin axis.

In the present embodiment, the position of the foot of the perpendicular line that is lowered from the contact point of the kingpin shaft to a straight line in the direction of the side slip angle β of the tire passing through the tire contact center is set to be within the tire contact surface.
For example, the kingpin axis is set to a positive scrub with a caster angle of 0 degrees, a caster trail of 0 mm, and a scrub radius of 0 mm or more. The kingpin inclination angle is set within a range where the scrub radius can be a positive scrub and a smaller angle (for example, 15 degrees or less).

By setting it as such a suspension geometry, the locus | trajectory of the tire ground-contact surface center at the time of steering becomes smaller, and a tire torsion torque can be reduced.
Therefore, since the rack axial force can be made smaller, the moment around the kingpin axis can be made smaller, and the output of the steered actuator 8 can be reduced. Moreover, the direction of the wheel can be controlled with a smaller force. That is, maneuverability and stability can be improved.

In the suspension device 1B according to the present embodiment, since the two lower link members are installed so as to intersect with each other, the virtual lower pivot point is more easily arranged on the inner side of the vehicle than the center of the tire contact surface.
Therefore, it becomes easy to make the kingpin inclination angle close to 0 degrees, and it becomes easy to make the scrub radius large on the positive scrub side.

Moreover, there is a possibility that the straightness on the suspension structure may be affected by setting the caster angle to 0 degrees and the caster trail to 0 mm. However, by setting the positive scrub, the influence is reduced. Further, in addition to the control by the steering actuator 8, the straightness is ensured. That is, maneuverability and stability can be improved.
In addition, when the kingpin tilt angle is limited to a certain range, when the steering actuator 8 performs steering, it is possible to avoid the driver from feeling heavy in the steering operation. Further, the kickback due to the external force from the road surface can be countered by the steering actuator 8, so that the influence on the driver can be avoided. That is, maneuverability and stability can be improved.

As described above, according to the suspension device 1B according to the present embodiment, the lower link members are arranged so as to intersect with each other in the vehicle top view, so that the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction. Then, the virtual kingpin axis Roapibotto point is defined as the kingpin inclination is small, the ground point of the kingpin axis, the position of the foot of the perpendicular dropped to the straight line of the side slip angle β direction of the tire is a tire contact through the tire contact center since was set to position in the ground, it is possible to further reduce the moment around the kingpin axis.

Accordingly, the steering can be performed with a smaller rack axial force, and the direction of the wheel can be controlled with a smaller force, so that the maneuverability and stability can be improved.
Further, since the moment around the kingpin axis can be further reduced, the load applied to the steering rack member 14 and the tie rod 15 can be reduced, and the member can be simplified.

Further, as the steering actuator 8 for realizing the steer-by-wire, one having a lower driving ability can be used, and the cost and weight of the vehicle can be reduced.
For example, when compared with a conventional steer-by-wire type suspension device, the configuration of the present invention is approximately 10% in weight and approximately 50% in cost mainly due to simplification of the lower link member and downsizing of the steering actuator 8. Can be reduced.

Further, since the caster trail is increased at the time of turning, it is possible to suppress the turning angle from being increased during turning in which high lateral acceleration is generated.
Further, since the virtual lower pivot point moves to the inner side of the vehicle body due to the lateral force acting on the wheel at the time of turning, the scrub radius is increased, and the straightness by the self-aligning torque (SAT) can be improved.
Further, by installing the lower link members so as to intersect with each other, the connection point of the lower link members can be located close to the center of the wheel, so that the weight of the axle carrier 33 can be reduced.

  FIG. 11 is a diagram schematically showing the relationship between the kingpin tilt angle and the scrub radius in the present invention. In FIG. 11, in addition to the case where the present invention is the compression type, when the present invention is a tension type, as a comparative example, a compression type and a tension type having a structure in which the lower link members are not crossed (see Application Example 1). ) And a case of a single pivot system are also shown.

As shown in FIG. 11, when the present invention is realized as a compression type and a tension type, the kingpin inclination angle can be made close to 0 degrees as compared with the single pivot method and the double pivot method in which the lower link members are not intersected. The scrub radius can be increased on the positive scrub side.
In particular, when the present invention is realized as a compression type, a higher effect can be achieved in terms of an effect of bringing the kingpin inclination angle close to 0 degrees and an effect of increasing the scrub radius toward the positive scrub side.
The suspension device 1B according to the present invention can be applied to suspension devices other than the strut type.

FIG. 12 is a diagram showing a structural example in which the present invention is applied to a suspension device having a knuckle.
In the example shown in FIG. 12, the upper end of the knuckle is connected to the upper arm member, and the second link (compression rod) 38 straddles the first link (tension rod) 37, thereby crossing each other in the vehicle top view. ing. In this case, the upper end of the knuckle is the virtual upper pivot point, and the intersection of the first link and the second link is the virtual lower pivot point.

With this structure, the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction, as in the case of the strut type. Since the from the ground point of the kingpin axis defined virtual Roapibotto point, was set to the position of the foot of the perpendicular dropped to the straight line of the side slip angle β direction of the tire through the tire ground contact center is position in the tire ground contact surface, The moment around the kingpin axis can be further reduced.
In the present embodiment, the wheels 17FR, 17FL, 17RR, and 17RL correspond to the tire wheel, the tire, and the wheel hub mechanism, the first link 37 corresponds to the first link member, and the second link 38 corresponds to the second link. Corresponds to the link member. The rack shaft 14 corresponds to a steering rack.

(Effect of 1st Embodiment)
(1) The first link member and the second link member that connect the wheel hub mechanism and the vehicle body below the vehicle axle in the vertical direction of the vehicle are arranged so as to intersect with each other when viewed from above the vehicle.
As a result, the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction. Therefore, the moment around the kingpin axis can be further reduced.
Therefore, the steering can be performed with a smaller rack axial force, and the direction of the wheel can be controlled with a smaller force. That is, maneuverability and stability can be improved.

(2) The first link member and the second link member are disposed rearward in the vehicle front-rear direction with respect to the axle.
Therefore, the present invention can be realized as a compression type suspension device.
(3) In the compression-type suspension device, the steering rack is disposed in front of the vehicle front-rear direction with respect to the axle.
Therefore, since the wheel moves to the inside of the turn at the time of turning, the axial force of the steering rack can be reduced.

(4) The steered wheel by the steer-by-wire system is suspended by the vehicle suspension device.
Therefore, the steering actuator in the steer-by-wire system can be used to perform control corresponding to the caster trail setting in the present invention, and the maneuverability and stability can be improved.
(5) The configuration is such that the position of the foot of the perpendicular line that is lowered from the contact point of the kingpin shaft to the straight line in the direction of the side slip angle β of the tire passing through the tire contact center is positioned within the tire contact surface.
As a result, the moment around the kingpin axis can be further reduced, so that the steering can be performed with a smaller rack axial force and the direction of the wheel can be controlled with a smaller force.
Therefore, maneuverability and stability can be improved.

(6) When the vehicle is viewed from above, the lower link member that connects the vehicle body and the wheel is installed so as to intersect, and the virtual lower pivot point is used as the intersection of the link member.
As a result, the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction. Therefore, the moment around the kingpin axis can be further reduced.

(Application 1)
(Another specific configuration example of the suspension device 1B)
In the first embodiment, the specific configuration example of the suspension device 1B has been described by taking the case of the compression type as an example. However, the following configuration may be employed.
FIG. 13 is a schematic diagram illustrating an example in which the suspension device 1B is configured by a tension type suspension device (a type in which each lower link member is located on the vehicle front side from the axle in a top view of the vehicle).
That is, in the example shown in FIG. 13, the compression rod (second link 38) is connected to the vehicle body at a position where the compression rod (second link 38) extends along the axle and the tension rod (first link 37) extends forward from the axle when viewed from above the vehicle.

  As shown in FIG. 13, in a tension-type suspension device, when the lower link member is a double pivot system in which the lower link members intersect with each other, each lower link member turns by rotating forward of the vehicle around the vehicle body side support point. Steering as an outer wheel is possible (in a broken line state). At this time, the virtual lower pivot point is the point where the lower link member intersects, but since the virtual lower pivot point can be formed inside the vehicle body rather than the suspension type where the lower link member does not intersect, the initial scrub radius is set in the positive scrub direction. Can be big.

  In the tension type suspension device shown in FIG. 13, the rotation angle of the tension rod at the time of turning is large, so the virtual lower pivot point moves to the outside of the vehicle body. In this case, in the vehicle top view, the distance from the tire center line to the virtual lower pivot point in the front-rear direction of the tire moves to the vehicle body outer side direction than the tire center line, so the scrub radius is smaller within the positive scrub range. . Therefore, in the tension type suspension device, when the present invention is applied, the rack axial force is increased by turning as a turning outer wheel, but the initial scrub radius when not turning is sufficiently large. The rack axial force value can be set smaller than that of a tension type suspension device in which the lower link members do not intersect.

  Incidentally, in the case of a tension type suspension device in which the lower link members do not intersect, the virtual lower pivot point moves to the inside of the vehicle body because the rotation angle of the tension rod at the time of turning is large. In this case, the scrub radius increases in the positive scrub direction because the distance from the tire center line to the virtual pivot point in the front-rear direction of the tire is located on the vehicle body inner side than the tire center line in the vehicle top view. Therefore, the rack axial force is reduced by turning. However, since the virtual lower pivot point is on the extension line of each link, the scrub radius in the initial state where the steering is not performed is small, and it is difficult to significantly reduce the rack axial force.

Further, in the example shown in FIG. 13, the wheel center moves to the outside of the turn at the time of turning in the vehicle top view. Therefore, the effect of reducing the rack axial force can be further enhanced by positioning the rack shaft 14 behind the axle as in the present embodiment.
The present invention can be similarly applied to a suspension device having a link structure other than the compression type and the tension type.

(effect)
(1) The first link member and the second link member are disposed in front of the vehicle front-rear direction with respect to the axle.
Therefore, the present invention can be realized as a tension type suspension device.
(2) In the tension-type suspension device, the steering rack is arranged behind the axle in the vehicle front-rear direction.
For this reason, the wheel moves to the outside of the turn at the time of turning, so that the axial force of the steering rack can be reduced.

(Application example 2)
In the first embodiment, the case where the suspension device 1B is applied to a front wheel suspension device that is a steered wheel has been described as an example. However, the suspension device 1B may be applied to a rear wheel suspension device that is a non-steered wheel. Is possible.
In this case, when the vehicle turns by turning and a lateral force acts on the rear wheel, the tension rod and the compression rod are deflected by the lateral force, and the intersection point in the vehicle top view moves, and the wheel against the vehicle body moves. The direction changes (see FIGS. 8 and 13). That is, the lower link member along the axle has less movement in the front-rear direction due to the lateral force, and the other lower link member installed at an angle in the front-rear direction with respect to the axle has a greater movement in the front-rear direction due to the lateral force. .
By utilizing this characteristic, a desired lateral force compliance steer can be realized.

(effect)
The first link member and the second link member that connect the wheel hub mechanism and the vehicle body are arranged below the axle in the vehicle vertical direction so as to intersect with each other when viewed from above the vehicle.
As a result, the link member bends due to the lateral force during turning, and the direction of the wheel relative to the vehicle body can be changed by moving the intersection of the link member when the vehicle is viewed from above.
Therefore, the target lateral force compliance steer can be realized.

(Application 3)
In the first embodiment, the case where the suspension device 1B is applied to a front wheel suspension device that is a steered wheel has been described as an example. However, the suspension device 1B can also be applied to a rear wheel suspension device that is a steered wheel. It is.
Also in this case, similarly to the first embodiment, the virtual lower pivot point can be brought closer to the inside of the vehicle body in the vehicle width direction. And since the position of the foot of the perpendicular line that fell from the grounding point of the kingpin axis defined by this virtual lower pivot point to the straight line in the side slip angle β direction of the tire passing through the tire grounding center was set in the tire grounding surface, the kingpin axis The moment around can be made smaller.
Accordingly, the steering can be performed with a smaller rack axial force, and the direction of the wheel can be controlled with a smaller force, so that the maneuverability and stability can be improved.

(Application 4)
In the first embodiment, the position of the foot of a perpendicular line that is a straight line in the direction of the side slip angle β of the tire passing through the tire ground contact center from the ground contact point of the kingpin shaft in the tire ground contact surface is set. The case where the trail is set to a value close to zero has been described.
On the other hand, in this application example, the setting condition of the caster trail, that is, the position of the foot of the perpendicular line, which is a straight line in the direction of the side slip angle β of the tire passing from the ground contact point of the kingpin shaft to the tire ground contact center from the tire contact surface center to the tire contact surface. It shall be limited to the range up to the front edge of the ground.
(effect)
If the position of the leg of the perpendicular line that extends down from the kingpin shaft contact point to the straight line in the direction of the side slip angle β of the tire passing through the tire contact center is set from the center of the tire contact surface to the front end of the tire contact surface, the caster trail also becomes the tire contact surface. It is set from the center to the front end of the tire ground contact surface, and it is possible to ensure both straightness and a reduction in the weight of the steering operation. That is, maneuverability and stability can be improved.

(Application example 5)
In the first embodiment, in the coordinate plane shown in FIG. 7, a region surrounded by a one-dot chain line is taken as an example of a region suitable for setting. On the other hand, an isoline of the rack axial force of interest is used as a boundary line, and an area inside the range indicated by the boundary line (in the decreasing direction of the kingpin tilt angle and the increasing direction of the scrub radius) is set as an area suitable for setting. it can.
(effect)
Assuming the maximum value of the rack axial force, the suspension geometry can be set within the range below the maximum value.

(Application example 6)
In the first embodiment and each application example, the case where the suspension device 1B is applied to a vehicle including a steer-by-wire steering device has been described as an example. However, the steering device is not a steer-by-wire method but a mechanical steering mechanism steering device. The suspension device 1B can be applied to a vehicle including
In this case, the kingpin axis is determined according to the conditions based on the above examination results, and the position of the foot of the perpendicular line that is lowered from the grounding point of the kingpin axis to a straight line in the side slip angle β direction of the tire passing through the tire grounding center is within the tire grounding surface. After setting, the link arrangement of the mechanical steering mechanism is configured accordingly.
(effect)
Even in a steering mechanism having a mechanical structure, it is possible to reduce the moment around the kingpin and reduce the steering force required by the driver, and to improve maneuverability and stability.

DESCRIPTION OF SYMBOLS 1 Car, 1A Car body, 1B Suspension device, 2 Steering wheel, 3 Input side steering shaft, 4 Handle angle sensor, 5 Steering torque sensor, 6 Steering reaction force actuator, 7 Steering reaction force actuator angle sensor, 8 Steering actuator, 9 Steering actuator angle sensor, 10 output side steering shaft, 11 steering torque sensor, 12 pinion gear, 13 pinion angle sensor, 14 steering rack member, 15 tie rod, 16 tie rod axial force sensor, 17FR, 17FL, 17RR, 17RL wheel, 18 Brake disc, 19 Wheel cylinder, 20 Pressure control unit, 21 Vehicle state parameter acquisition unit, 24FR, 24FL, 24RR, 24RL Wheel speed sensor, 26 Drive circuit unit, 27 Mechanism Nical backup, 32 axles, 33 axle carrier, 34 spring member, 37 first link (first link member), 38 second link (second link member), 40 shock absorber

Claims (7)

A control / drive circuit unit that steers the steered wheels by operating an actuator according to the steering state of the steering wheel;
A suspension device for supporting the steered wheels on a vehicle body,
The suspension device includes: a wheel hub mechanism that supports a tire wheel to which a tire is attached; a first link member that connects the wheel hub mechanism and the vehicle body below the axle in a vehicle vertical direction; A second link member that connects the wheel hub mechanism and the vehicle body at a lower side in the direction and intersects the first link member in a top view of the vehicle;
The foot of a perpendicular line that has been lowered from the grounding point of the kingpin shaft with the intersection of the first link member and the second link member as viewed from the top of the vehicle to the lower pivot point and passing through the tire grounding center in the direction of the side slip angle of the tire. Set the position to be within the tire contact surface,
The control / drive circuit unit operates the actuator to generate a restoring force for self-aligning the steered wheels to steer the steered wheels and ensure straightness of the vehicle. Automobile. 2. The automobile according to claim 1, wherein the vehicle body side mounting positions of the first link member and the second link member are arranged rearward in the vehicle front-rear direction with respect to the axle. The automobile according to claim 2, wherein a steering rack member that moves in a vehicle width direction and steers the wheel hub mechanism is arranged in front of the vehicle front-rear direction with respect to the axle. It said first link member and the vehicle body-side mounting position of the second link member, an automobile according to claim 1, characterized in that arranged in the longitudinal direction forward vehicle than the axle. The automobile according to claim 4, wherein a steering rack member that moves in a vehicle width direction and steers the wheel hub mechanism is disposed rearward in the vehicle front-rear direction with respect to the axle. The automobile according to any one of claims 1 to 5, wherein a steered wheel by a steer-by-wire system that detects displacement of the steering wheel and displaces the steering rack by an actuator based on the detection result is suspended. The automobile according to any one of claims 1 to 6, wherein the suspension geometry determined by the kingpin axis is set to a positive scrub.

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