CN107719052B - Suspension device - Google Patents

Suspension device Download PDF

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Publication number
CN107719052B
CN107719052B CN201710821816.4A CN201710821816A CN107719052B CN 107719052 B CN107719052 B CN 107719052B CN 201710821816 A CN201710821816 A CN 201710821816A CN 107719052 B CN107719052 B CN 107719052B
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China
Prior art keywords
toe
suspension device
steering
turning
force
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Active
Application number
CN201710821816.4A
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Chinese (zh)
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CN107719052A (en
Inventor
小暮胜
塚崎裕一郎
齐藤正容
诸田和也
绵贯贤二
日向俊行
山田大辅
大岛健介
宇津木芳明
仲武圣仁
富泽英久
井本昌志
石田斗志
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Subaru Corp
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Subaru Corp
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Priority claimed from CN201410130829.3A external-priority patent/CN104070954B/en
Publication of CN107719052A publication Critical patent/CN107719052A/en
Application granted granted Critical
Publication of CN107719052B publication Critical patent/CN107719052B/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G3/00—Resilient suspensions for a single wheel
    • B60G3/18—Resilient suspensions for a single wheel with two or more pivoted arms, e.g. parallelogram
    • B60G3/20—Resilient suspensions for a single wheel with two or more pivoted arms, e.g. parallelogram all arms being rigid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/015—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements
    • B60G17/016—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input
    • B60G17/0162—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input mainly during a motion involving steering operation, e.g. cornering, overtaking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/015—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements
    • B60G17/016—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input
    • B60G17/0162—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input mainly during a motion involving steering operation, e.g. cornering, overtaking
    • B60G17/0163—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input mainly during a motion involving steering operation, e.g. cornering, overtaking the control involving steering geometry, e.g. four-wheel steering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D17/00—Means on vehicles for adjusting camber, castor, or toe-in
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/10—Independent suspensions
    • B60G2200/18—Multilink suspensions, e.g. elastokinematic arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/40—Indexing codes relating to the wheels in the suspensions
    • B60G2200/462—Toe-in/out
    • B60G2200/4622—Alignment adjustment

Abstract

The present invention provides a rear wheel suspension device capable of suppressing or canceling the influence of vertical force flexible steering occurring at the initial stage of turning, comprising: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle is rotatable about an axle; a suspension link, both ends of which are respectively mounted on the vehicle body and the hub bearing in a swingable manner, and which supports the hub bearing bracket in a manner that a stroke is generated with respect to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, and has a vertical force steer-by-wire characteristic that steers the rear wheel to a toe-in side or a toe-out side by increasing a vertical force acting on a tread of the rear wheel, and a toe-angle change generation means that temporarily generates a toe-angle change in a direction that cancels or suppresses the toe-angle change caused by the vertical force steer-by-wire characteristic at an initial stage of turning of the vehicle.

Description

Suspension device
The present application is a divisional application of a patent application having an application date of 2014, month 28, application number of 201410130829.3, and a name of "suspension device".
Technical Field
The present invention relates to a suspension device for a rear wheel of an automobile, and more particularly to a suspension device for a rear wheel capable of suppressing or canceling the influence of vertical force steer occurring at the initial stage of turning.
Background
A rear wheel suspension device for a vehicle such as an automobile supports a hub bearing bracket that rotatably supports a rear wheel, by a suspension link (link) that is swingably attached to a vehicle body such that the hub bearing bracket is movable back and forth in a vertical direction with respect to the vehicle body.
In such a rear wheel suspension device, for example, the rear wheel is positioned in the camber direction by a pair of upper and lower transverse links, and the toe direction is positioned by a pair of lower transverse links arranged at a distance in the front-rear direction.
As an example of such a rear wheel suspension device, patent document 1 discloses the following: the wheel hub bearing brackets are positioned using front and rear transverse links (lower links) and longitudinal links that are swingably mounted on a subframe that is mounted below the rear of the vehicle body.
One or both end portions of each link are connected to the vehicle body or the hub bearing bracket via a rubber bush for vibration prevention.
For example, when a lateral force acts during turning of the vehicle, a lateral force flexible steering is generated in which the toe angle of the rear wheel changes in the toe-in (toe in) or toe-out (toe out) direction due to the difference in the amount of deformation of the rubber bushings of the front and rear lateral links.
In general, when the vehicle is turning, it is preferable that the turning outer wheel side is toe-in and the turning inner wheel side is toe-out, and therefore, when the rigidity of the rubber bushings of the front and rear transverse links is set, the amount of displacement with respect to the transverse force tends to be set larger on the front side than on the rear side.
In addition, the geometrical arrangement (ジオメトリー: Geometry) of the links constituting the suspension is also generally given the following bump step (bump step) characteristics: the toe-in tendency is on the side of the turning outer wheel, i.e., the kick-up side (compression side), and the toe-out tendency is on the side of the turning inner wheel, i.e., the rebound side (expansion side).
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2011-57021
However, as described above, in a suspension that exhibits such a lateral force compliant steering that the outer wheel side is toe-in and the inner wheel side is toe-out due to a lateral force at the time of turning, there is a case where the outer wheel side is toe-out and the inner wheel side is toe-in at the initial stage of turning due to a compliant steering (vertical force compliant steering) due to a vertical force.
Then, when the lateral force increases and the stroke of the suspension starts, and lateral force steer by soft steering or bump steering occurs, the outer wheel side tends to be toe-in and the inner wheel side tends to be toe-out, but the wheels are steered in reverse phase once after the initial period of turning, and the steering stability is degraded.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a rear wheel suspension device capable of suppressing or canceling the influence of vertical force buckling occurring at the initial stage of turning.
The present invention solves the above problems by the following solutions.
A first aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer-compliant characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, and the suspension device further includes a toe-angle change generating means that temporarily generates a toe-angle change in a direction to cancel or suppress the toe-angle change caused by the vertical force steer-compliant characteristic at an initial stage of turning of the vehicle.
Accordingly, in the initial stage of turning in which the influence of the vertical force steer-by-wire is significant, the toe angle change in the direction that cancels or suppresses the characteristic is generated, whereby the toe angle reversal of the rear wheels can be prevented and the driving stability can be improved.
A second aspect of the present invention is the suspension device according to the first aspect, wherein the toe angle change generating means includes braking/driving force difference generating means for generating a braking/driving force difference between the left and right rear wheels.
Accordingly, the toe angle change in a desired direction can be generated with a simple configuration by utilizing the front-rear force flexible steering characteristic of the suspension.
A third aspect of the present invention is the suspension device according to the second aspect, characterized by having a wheel center tow-toe characteristic in which the hub bearing bracket is offset in a toe-toe direction by a braking force acting on the wheel center, and the braking-driving force difference generating unit has a driving unit capable of individually controlling the driving forces of the left and right wheels, and increases the driving force on the turning outer wheel side with respect to the turning inner wheel side.
A fourth aspect of the present invention is the suspension device according to the second aspect, wherein the braking/driving force difference generating means has a wheel center toe-in characteristic in which the wheel center bearing bracket is displaced in a toe-in direction by a braking force acting on the wheel center, and the braking/driving force difference generating means has a braking means capable of individually controlling the braking forces of the left and right wheels, and reduces the braking force on the outer wheel side of the turn with respect to the inner wheel side of the turn.
A fifth aspect of the present invention is the suspension device according to the second aspect, wherein the suspension device has a wheel center tow-toe characteristic in which the hub bearing bracket is offset in a toe-toe direction by a braking force acting on a wheel center, and the braking/driving force difference generating means has a driving means capable of individually controlling driving forces of the left and right wheels and a braking means capable of individually controlling braking forces of the left and right wheels, and applies the braking force to an inner wheel in a turn and applies the driving force to an outer wheel in the turn.
According to these inventions, the above-described effects can be reliably obtained.
A sixth aspect of the present invention is the suspension device according to the third or fifth aspect, wherein the drive unit includes drive motors provided on the left and right rear wheels, respectively.
Accordingly, the driving forces of the left and right rear wheels can be easily and appropriately controlled.
A seventh aspect of the present invention is the suspension device according to any one of the first to fifth aspects, wherein the toe-angle change generating means performs the toe-angle change generation control so as to change the toe-angle change amount in accordance with a change in vertical load of the rear wheel.
Since the toe angle change amount (steering amount) caused by the vertical force flexible steering changes in accordance with the vertical load of the rear wheels, the toe angle change amount can be appropriately set in accordance therewith to further improve the driving stability.
An eighth aspect of the present invention is the suspension device according to any one of the first to fifth aspects, wherein the toe-angle change generating means gradually changes and reduces the toe-angle change amount when the toe-angle change generation is completed.
This prevents the driver from feeling uncomfortable due to a sudden change in the toe angle.
A ninth aspect of the present invention is the suspension device according to any one of the first to fifth aspects, wherein the toe-angle change generating means ends the generation of the toe-angle change in response to strokes of the suspension spring and the shock absorber reaching a predetermined value or more.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented, and driving stability can be further improved.
A tenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a rear wheel steering driver that applies a steering angle to a rear wheel, and the suspension device has a vertical force steer-by-wire characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, the rear wheel steering driver applying the steering angle to the rear wheel in a direction that temporarily cancels or suppresses a change in the toe-out angle caused by the vertical force steer-by-wire characteristic at an initial stage of turning of the vehicle.
Accordingly, by applying a steering angle in a direction that cancels or suppresses a toe angle change caused by vertical force steer-compliant steering to the rear wheel using the rear wheel steering actuator, it is possible to prevent a toe angle change of the inner wheel to the toe-in side and to prevent a temporary toe-out of the outer wheel to the toe-out side at the initial stage of turning, thereby improving driving stability.
An eleventh aspect of the present invention is the suspension device according to the tenth aspect, wherein the rear wheel steering actuator applies the steering angle to the rear wheels so as to change the steering angle in accordance with a change in vertical load of the rear wheels.
Accordingly, by applying a steering angle that changes in accordance with the vertical load, it is possible to apply a steering angle that corresponds to a change in toe resulting from a vertical force compliant steering, and to suppress a feeling of discomfort due to a sudden change in toe.
A twelfth aspect of the present invention is the suspension device according to the tenth or eleventh aspect, wherein the rear wheel steering actuator gradually changes and decreases the steering angle when application of the steering angle is completed.
This prevents a sudden change in the toe angle at the end of toe angle correction, and suppresses a feeling of discomfort due to a sudden change in the toe angle.
A thirteenth aspect of the present invention is the suspension device according to the tenth or eleventh aspect, wherein the rear wheel steering actuator terminates the application of the steering angle in response to a stroke of the suspension spring and the damper being equal to or greater than a predetermined value.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented and driving stability can be further improved.
A fourteenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer-compliant characteristic in which the rear wheel is steered to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, and the suspension device further includes a damping control means that temporarily reduces the damping force of the damper at an initial stage of turning of the vehicle.
Accordingly, by reducing the damping force of the damper at the initial stage of turning, the stroke of the suspension can be promoted, bump steering and lateral force compliant steering can be generated at an early stage, and the time for temporarily turning the outer wheel to the toe-out side and the inner wheel to the toe-in side by the vertical force compliant steering can be shortened, thereby improving the driving stability.
A fifteenth aspect of the present invention is the suspension device according to the fourteenth aspect, wherein the damping control means ends the reduction of the damping force in response to a stroke of the suspension spring and the damper reaching a predetermined value or more.
Accordingly, by generating the stroke of the shock absorber, the damping force of the shock absorber is returned to the original state after the influence of the vertical force flexible steering is cancelled out by the bump steering or the like, and thus the insufficient damping during the turning can be prevented to further improve the driving stability.
A sixteenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a stabilizer device that generates a reaction force according to a stroke difference between the left and right shock absorbers, wherein the suspension device has a vertical force flexible steering characteristic that steers the rear wheel to a toe-in side or a toe-out side according to an increase in a vertical force acting on a tread of the rear wheel, and the suspension device further includes a roll rigidity control means that temporarily reduces roll rigidity of the stabilizer device at an initial stage of turning of the vehicle.
Accordingly, by reducing the roll rigidity of the stabilizer at the initial stage of turning, the stroke of the suspension can be promoted, the bump steering and the lateral force flexible steering can be generated at an early stage, and the time for temporarily turning the outer wheel to the toe-behind side and the inner wheel to the toe-behind side by the vertical force flexible steering can be shortened, thereby improving the driving stability.
A seventeenth aspect of the present invention is the suspension device according to the sixteenth aspect, wherein the roll rigidity control means ends the decrease in the roll rigidity in response to a stroke of the suspension spring and the shock absorber becoming equal to or greater than a predetermined value.
Accordingly, by generating the stroke by the damper, the roll rigidity returns to the original state after the influence of the vertical force buckling steering is cancelled by the bumping steering or the like, and the roll rigidity is prevented from being insufficient at the time of steady turning, thereby improving the driving stability.
An eighteenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both end portions swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to be able to be generated with respect to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer-compliant characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, the suspension device further includes a toe angle change generating means that temporarily generates a toe angle change in an initial turning stage of the vehicle in a direction that cancels or suppresses the toe angle change caused by the vertical force steer-compliant characteristic, and the toe angle change generating means has a stroke control means that forcibly generates a stroke on a compression side of the damper on an outer turning wheel side.
Accordingly, the shock absorber on the turning outer wheel side is forcibly stroked on the compression side at the initial stage of turning, so that the bump steering can be generated at an early stage, and the outer wheel is prevented from being temporarily steered to the toe-back side due to the flexible steering by the vertical force, thereby improving the driving stability.
A nineteenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, the suspension device further includes a toe angle change generating unit that temporarily generates a toe angle change in an initial turning stage of the vehicle in a direction that cancels or suppresses the toe angle change caused by the vertical force steer characteristic, and the toe angle change generating unit has a load applying unit that applies a compressive load to the damper on an outer turning wheel side.
Accordingly, by applying a compression load to the damper on the outer wheel side at the initial stage of turning, the input load to the damper can be increased, the lock of the damper can be released at an early stage to promote the initial stroke, the jerk steering characteristic can be generated at an early stage, and the period in which the influence of the vertical force flexile steering characteristic is exhibited can be shortened to improve the driving stability.
A twentieth aspect of the present invention is the suspension device according to the eighteenth or nineteenth aspect, wherein the toe angle change generating means terminates the generation of the toe angle change in response to a load of the absorber load on the turning outer wheel side becoming equal to or greater than a predetermined value.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented and driving stability can be further improved.
A twenty-first aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical-force-compliant steering characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, the suspension device further includes a toe-angle-change generating means that temporarily generates a toe-angle change in an initial turning stage of the vehicle in a direction that cancels or suppresses the toe-angle change caused by the vertical-force-compliant steering characteristic, and the toe-angle-change generating means includes a roll-torque generating means that generates a roll torque in a direction in which the damper on an outer turning wheel side is compressed.
Accordingly, by forcibly generating roll according to the roll torque generating unit such as the active stabilizer, the suspension is stroked, so that the bump steering can be generated at an early stage, and the outer wheel can be prevented from being temporarily turned to the toe-back side according to the vertical force compliant steering, thereby improving the driving stability.
A twenty-second aspect of the present invention is the suspension device according to the twenty-first aspect, wherein the toe-angle change generating means ends the generation of the toe-angle change in response to a stroke of the suspension spring and the damper being equal to or greater than a predetermined value.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented and driving stability can be further improved.
A thirteenth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, the suspension device further includes a toe angle change generating means that temporarily generates a toe angle change in an initial turning stage of the vehicle in a direction that cancels or suppresses the toe angle change caused by the vertical force steer characteristic, and the toe angle change generating means has a bracket rigidity control means that temporarily increases a rigidity of an adjustable rigid elastomer bracket provided between an upper end portion of the damper and the vehicle body in the initial turning stage.
Accordingly, the stiffness of the adjustable-stiffness elastomer mount is temporarily increased at the initial stage of turning, so that the initial input to the damper is increased, the action-promoting stroke of the damper is released at an early stage, the jerk steering characteristic is generated at an early stage, and the period in which the influence of the vertical-force flexible steering characteristic is exhibited is shortened, thereby improving the driving stability.
A twenty-fourth aspect of the present invention is the suspension device according to the twenty-third aspect, wherein the bracket rigidity control unit returns the rigidity of the adjustable-rigidity elastic-body bracket to a state before a turn starts, in accordance with a stroke of the shock absorber being equal to or greater than a predetermined value.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented and driving stability can be further improved.
Further, by relatively reducing the rigidity of the stay at the initial stage of turning other than the initial stage of turning, the vibration and the riding feeling can be improved.
A twenty-fifth aspect of the present invention is a suspension device including: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension link includes a front cross link and a rear cross link that perform positioning in a toe angle direction of the hub bearing bracket, and that have an elastic body sleeve on at least one of an end portion on the vehicle body side and an end portion on the hub bearing bracket side, and that cause a receiving tensile force in accordance with a vertical load of the rear wheel when the vehicle is traveling straight, and the suspension device further includes a rigidity adjustable unit that temporarily relatively increases a rigidity of the elastic body sleeve of the front cross link with respect to a rigidity of the elastic body sleeve of the rear cross link at an initial stage of turning.
Accordingly, even when the lateral rigidity of the rubber sleeve of the front transverse link is set to be relatively low with respect to the rigidity of the rubber sleeve of the rear transverse link in order to cause a toe-in angle change in the toe-in direction of the outer wheel and the inner wheel during turning in accordance with the lateral force flexile steering, the difference in rigidity between the front and rear transverse links is temporarily reversed at the initial stage of turning where the vertical force flexile steering is problematic, whereby the toe-in angle change in the toe-in direction of the inner wheel due to the outer wheel and the inner wheel caused by the vertical force flexile steering can be prevented to improve the driving stability.
A twenty-sixth aspect of the present invention is the suspension device according to the twenty-fifth aspect, wherein the rigidity adjustable unit temporarily increases the rigidity of the rubber bush of the front cross link at an initial stage of turning.
A twenty-seventh aspect of the present invention is the suspension device according to the twenty-fifth or twenty-sixth aspect, wherein the rigidity adjustable unit temporarily lowers the rigidity of the rubber bush of the rear cross link at an initial stage of turning.
Accordingly, the above-described effects can be reliably obtained.
A twenty-eighth aspect of the present invention is the suspension device according to the twenty-fifth or twenty-sixth aspect, wherein the rigidity adjusting means restores the rigidity of the rubber bush to a state before a turning start in accordance with a stroke of the suspension spring and the damper being equal to or greater than a predetermined value.
Accordingly, in a steady turning state in which adverse effects due to vertical force steer compliance are unlikely to occur, the toe angle change in the toe-in direction of the outer wheel and the toe-out direction of the inner wheel can be generated using the lateral force steer compliance, thereby further improving the driving stability of the vehicle.
A twenty-ninth aspect of the present invention is a suspension device, comprising: a hub bearing bracket that supports a rear wheel of a vehicle in such a manner that the rear wheel of the vehicle can rotate around an axle; a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body; a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body, wherein the suspension device has a vertical force steer-compliant characteristic that steers the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel, and further comprises a toe-angle change generating means that temporarily generates a toe-angle change in an initial turning stage of the vehicle in a direction that cancels or suppresses the toe-angle change caused by the vertical force steer-compliant characteristic, the toe-angle change generating means temporarily changing an elastic constant of an adjustable rigid sleeve provided in a part of the suspension link and being capable of rotating the hub bearing bracket in the toe-in direction or the toe-out direction by changing the elastic constant.
Accordingly, by temporarily changing the spring constant of the adjustable rigid sleeve provided in the suspension link at the initial stage of turning, the hub bearing bracket is rotated so that the toe-in direction is achieved on the outer wheel side and the toe-out direction is achieved on the inner wheel side, and thus it is possible to prevent or suppress a phenomenon in which the outer wheel is temporarily turned toward the toe-in side and the inner wheel is temporarily turned toward the toe-in side due to the flexible steering by the vertical force, and to improve the driving stability.
A thirtieth aspect of the present invention is the suspension device according to the twenty-ninth aspect, wherein the toe angle change generation unit terminates the generation of the toe angle change in response to a stroke of the suspension spring and the damper being equal to or greater than a predetermined value.
Accordingly, when sufficient toe angle changes of the outer wheel toward the toe-in side and the inner wheel toward the toe-out side can be obtained by bump steering and/or lateral force compliant steering, excessive toe angle changes can be prevented and driving stability can be further improved.
As described above, according to the present invention, it is possible to provide a rear wheel suspension device capable of suppressing or canceling the influence of vertical force buckling occurring at the initial stage of turning.
Drawings
Fig. 1 is a perspective view of an embodiment 1 to which a suspension device of the present invention is applied, as viewed from the front side.
Fig. 2 is a perspective view of the suspension device according to embodiment 1 as viewed from the rear side.
Fig. 3 is a front view of the suspension device of embodiment 1.
Fig. 4 is a rear view of the suspension device of embodiment 1.
Fig. 5 is a plan view of the suspension device of embodiment 1.
Fig. 6 is a bottom view of the suspension device of embodiment 1.
Fig. 7 is a side view of the suspension device of embodiment 1.
Fig. 8 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 1.
Fig. 9 is a flowchart showing toe correction control of the suspension device according to embodiment 1.
Fig. 10 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 1.
Fig. 11 is a flowchart of toe correction control in embodiment 2 to which the suspension device of the present invention is applied.
Fig. 12 is a graph showing the relationship between the top bracket load and the driving force correction amount in the suspension device of embodiment 2.
Fig. 13 is a graph showing the change in the driving force correction amount at the end of the normalized driving force correction in the suspension device according to embodiment 2.
Fig. 14 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 2.
Fig. 15 is a flowchart showing toe correction control in embodiment 3 of the suspension device to which the present invention is applied.
Fig. 16 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 4 to which the suspension device of the present invention is applied.
Fig. 17 is a flowchart showing toe correction control of the suspension device according to embodiment 4.
Fig. 18 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 5 to which the suspension device of the present invention is applied.
Fig. 19 is a flowchart showing toe correction control of the suspension device according to embodiment 5.
Fig. 20 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 5.
Fig. 21 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 6 to which the suspension device of the present invention is applied.
Fig. 22 is a flowchart showing toe correction control of the suspension device according to embodiment 6.
Fig. 23 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 7 to which the suspension device of the present invention is applied.
Fig. 24 is a flowchart showing toe correction control of the suspension device according to embodiment 7.
Fig. 25 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 7.
Fig. 26 is a block diagram showing a configuration of a control system of embodiment 8 to which a suspension device according to the present invention is applied.
Fig. 27 is a flowchart showing toe correction control of the suspension device according to embodiment 8.
Fig. 28 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 8.
Fig. 29 is a block diagram showing the configuration of a control system of embodiment 9 to which a suspension device of the present invention is applied.
Fig. 30 is a flowchart showing toe correction control of the suspension device according to embodiment 9.
Fig. 31 is a block diagram showing a configuration of a control system of embodiment 10 to which a suspension device of the present invention is applied.
Fig. 32 is a flowchart showing toe correction control of the suspension device according to embodiment 10.
Fig. 33 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 10.
Fig. 34 is a block diagram showing a configuration of a control system of embodiment 11 to which a suspension device of the present invention is applied.
Fig. 35 is a flowchart showing toe correction control of the suspension device according to embodiment 11.
Fig. 36 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 11.
Fig. 37 is a block diagram showing a configuration of a control system of embodiment 12 to which a suspension device of the present invention is applied.
Fig. 38 is a flowchart showing toe correction control of the suspension device according to embodiment 12.
Fig. 39 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 12.
Description of the symbols
1 suspension device
10 subframe
11 front component
12 rear component
13 side member
20 support
30 front transverse connecting rod
40 rear transverse connecting rod
50 upper connecting rod
60 longitudinal connecting rod
70 vibration damping unit
80 stabilizing device
100 suspension control system
110 Electric Power Steering (EPS) control unit
111 rudder angle sensor
112 torque sensor
120 motion control unit
121 LH (left side) brake
122 RH (Right side) brake
123 hydraulic control unit
124 vehicle speed sensor
130 drive control unit
131 LH (left side) motor
132 RH (Right side) motor
133 inverter
140 beam angle correction control unit
141 stroke sensor
142 top bracket load cell
150 CAN communication system
2304 WS (4Wheel Steering) control Unit
2314 WS motor
330 attenuation control unit
430 damping stroke control unit
530 Top cradle control Unit
630 Adjustable stabilizer control Unit
730 active stabilization control unit
830 sleeve rigidity control unit
930 Top support rigidity control Unit
1030 sleeve rigidity control unit
Detailed Description
The present invention solves the problem of providing a rear wheel suspension device capable of suppressing or canceling the influence of vertical force steer occurring at the initial stage of turning by applying a method such as a difference in braking/driving force between left and right wheels in a direction to cancel out the vertical force steer during a period from when steering is started until the stroke of the suspension reaches a predetermined value or more.
(example 1)
Embodiment 1 of a suspension device to which the present invention is applied is described below.
The suspension device of the embodiment is a double wishbone type suspension provided for rear wheels of an automobile such as a 4-wheel passenger car.
Fig. 1 is a perspective view of a suspension device according to embodiment 1 as viewed from the front side.
Fig. 2 is a perspective view of the suspension device according to embodiment 1 as viewed from the rear side.
Fig. 3 is a front view of the suspension device of embodiment 1.
Fig. 4 is a rear view of the suspension device of embodiment 1.
Fig. 5 is a plan view of the suspension device of embodiment 1.
Fig. 6 is a bottom view of the suspension device of embodiment 1.
Fig. 7 is a side view of the suspension device of embodiment 1.
The suspension device 1 includes a subframe 10, a bracket 20, a front cross link 30, a rear cross link 40, an upper link 50, a vertical link 60, a damper unit 70, a stabilizer 80, and the like.
The subframe 10 is a structural member serving as a base portion for mounting each link of the suspension device 1, and is mounted below a rear portion of a vehicle body, not shown, by a subframe sleeve having vibration-proof rubber.
The subframe 10 is configured to include a front member 11, a rear member 12, side members 13, and the like.
The front member 11 is a beam-like member provided at the front end portion of the subframe 10 and arranged substantially in the vehicle width direction.
Both end portions of the front member 11 are attached to the vehicle body via subframe sleeves.
The rear member 12 is a beam-like member provided at a rear end portion of the subframe 10 and arranged substantially in the vehicle width direction.
Both end portions of the rear member 12 are attached to the vehicle body via sub frame sleeves.
The side member 13 is a beam-like member that connects a portion near one end of the front member 11 and a portion near one end of the rear member 12 substantially in the vehicle front-rear direction.
A pair of left and right side members 13 are provided at intervals in the vehicle width direction.
The bracket 20 is a member that houses a hub bearing that can rotatably support a hub for mounting a wheel.
The suspension device 1 is a device that supports the bracket 20 so that the bracket 20 can move back and forth in the vertical direction along a predetermined trajectory with respect to the subframe 10.
The front and rear cross links 30, 40 are provided to span between the lower portion of the side member 13 and the lower portion of the bracket 20.
The front and rear transverse links 30, 40 are arranged substantially along the vehicle width direction and spaced apart in the vehicle front-rear direction.
Both end portions of the front cross link 30 and the rear cross link 40 are connected to the side member 13 and the bracket 20 via rubber bushings for vibration damping, respectively.
The upper link 50 is provided to span between an upper portion of the side member 13 and an upper portion of the bracket 20.
The upper link 50 is disposed substantially in the vehicle width direction.
Both end portions of the upper link 50 are connected to the side member 13 and the bracket 20 via a rubber bush for vibration damping and a ball joint, respectively, so as to be able to swing.
The vertical link 60 is provided so as to bridge between the vicinity of the side end of the front member 11 and the lower portion of the bracket 20.
The longitudinal link 60 is disposed substantially in the vehicle front-rear direction.
Both end portions of the vertical link 60 are connected to the front member 11 and the bracket 20 via rubber bushings for vibration isolation, respectively.
The damper unit 70 is a member in which a damper that generates a damping force corresponding to the expansion/contraction speed and a coil spring that generates a spring reaction force corresponding to the expansion/contraction amount are unitized.
The upper end of the damper unit 70 is attached to a vehicle body, not shown, via a roof bracket having a vibration-proof rubber.
The lower end portion of the damper unit 70 is attached to the rear cross link 40.
The stabilizer 80 is a tilt preventing device that generates a spring reaction force in a direction to reduce a difference in left and right stroke when a stroke in a reverse direction (anti-phase) is generated in the left and right of the suspension device 1.
The stabilizer 80 is formed of spring steel, and both ends of a stabilizer bar, which is disposed substantially in the vehicle width direction at the middle portion thereof, are connected to the left and right rear cross links 40 via links.
In the suspension device 1 described above, the rigidity of each sleeve is set so as to have the following lateral force compliant steering characteristics: due to the elastic deformation of the bushings of the front and rear transverse links 30, 40 caused by the lateral force due to the turning, the front toe tends to be restrained on the turning outer wheel side and the rear toe tends to be restrained on the turning inner wheel side.
Specifically, the rigidity in the lateral direction of the rubber bushings of the front cross link 30 is made lower relative to the rigidity in the lateral direction of the rubber bushings of the rear cross link 40.
In the suspension device 1, the following jounce-steering characteristics are obtained due to the geometry of each link: when the rear wheel makes a stroke in a direction (a rebound side) in which the rear wheel rises relative to the vehicle body, the steering is performed to a toe-in side, and when the rear wheel makes a stroke in a direction (a rebound side) in which the rear wheel falls relative to the vehicle body, the steering is performed to a toe-in side.
According to the transverse force flexible steering characteristic and the bump steering characteristic, the outer wheel is steered to the toe-in side and the inner wheel is steered to the toe-out side in the stable turning of the vehicle.
Further, the suspension device 1 has a so-called wheel center tow-back characteristic of steering the rear wheels in a tow-back direction when a braking force toward the wheel center is applied to the rear wheels.
On the other hand, in a state where the vehicle is moving straight forward, a tensile load is applied to the front and rear transverse links 30, 40 due to a vertical load of the rear wheels.
At the initial stage of turning of the vehicle, although a torque for rolling the vehicle body is generated, there is a region where the stroke of the suspension does not start due to the seizure (スティック) of the shock absorber or the like.
In such a region, the vertical load increases on the outer wheel side in a turn and decreases on the inner wheel side in a turn without actually causing the effect of the lateral force steer-compliant steering or the jerk steering.
Therefore, the tensile load acting on the front and rear transverse links 30, 40 increases on the turning outer wheel side and decreases on the turning inner wheel side.
Since the lateral rigidity of the rubber bushings of the front and rear transverse links 30, 40 is relatively low on the front transverse link 30 side as described above, the amount of displacement of the bracket 20 due to such a change in tensile load is greater on the front side than on the rear side.
Therefore, a vertical force flexible steering characteristic is produced in which the turning outer wheel is steered to the toe-in side and the turning inner wheel is steered to the toe-in side.
As described above, at the initial stage of turning, the influence of vertical force steer-by-steer is exhibited very strongly, and on the other hand, the influence of lateral force steer-by-steer and bump steer are hardly exhibited, and therefore, the turning outer wheel is steered to the toe-behind side, and the turning inner wheel is steered to the toe-behind side.
Then, when the damping unit 70 starts the stroke and the lateral force starts to act on the front and rear transverse links 30 and 40, the influence of the lateral force on the compliant steering and the bump steering becomes strong, and the turning outer wheel turns to the toe-in side and the turning inner wheel turns to the toe-out side.
In this way, if the rear wheels are steered in the opposite direction at the initial stage of turning and at the time of steady turning, the driving stability of the vehicle is adversely affected.
Therefore, in embodiment 1, the toe correction control is performed to generate the toe change in the direction to reduce or cancel the vertical force soft steering at the initial stage of turning.
This point is explained below.
Fig. 8 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 1.
The suspension control system 100 is configured to include an Electric Power Steering (EPS) control unit 110, an operation control unit 120, a drive control unit 130, a toe correction control unit 140, and the like.
These units CAN communicate with each other by, for example, the CAN communication system 150 which is one of the vehicle-borne LANs.
The EPS control unit 110 is a unit that controls an electric power steering apparatus that generates steering assist torque in accordance with torque input by a driver.
The EPS control unit 110 is connected to a steering angle sensor 111 and a torque sensor 112.
The steering angle sensor 111 is used to detect the current steering angle (steering wheel angle) of the steering system.
The torque sensor 112 is used to detect an input torque input to the steering system by the driver.
The motion control means 120 is configured to generate a difference in braking force between the left and right wheels and generate a moment in a direction to suppress the oversteering and the understeering of the vehicle.
The operation control unit 120 controls a hydraulic pressure control unit (HCU)123, and the hydraulic pressure control unit (HCU)123 can control the brake hydraulic pressures supplied to the LH brake 121 and the RH brake 122, respectively.
A vehicle speed sensor 124 is connected to the operation control unit 120, and the vehicle speed sensor 124 outputs a pulse signal corresponding to the rotational speed of the wheel, thereby acquiring the vehicle speed.
The drive control unit 130 is for performing drive control of applying a driving force by motors separately provided at the left and right rear wheels.
The drive control unit 130 can control the driving forces of the right and left rear wheels individually by controlling the inverters 133 that supply driving electric power to the LH motor 131 and the RH motor 132, respectively.
The LH motor 131 and the RH motor 132 are wheel motors provided at the hub portions of the left and right rear wheels, respectively, for example, but are not limited thereto, and may be configured to drive the left and right rear wheels from the subframe 10 through a propeller shaft.
The toe correction control unit 140 is configured to, when the start of turning is detected from information from the EPS control unit 110 or the like, perform toe correction control that temporarily generates a toe change in a direction in which the above-described vertical force steer is suppressed or cancelled.
The toe angle correction control unit 140 is connected to a stroke sensor 141 and a top bracket load sensor 142.
The stroke sensors 141 are used to detect the strokes of the dampers of the left and right damper units 70, respectively.
The top bracket load sensors 142 are used to detect vertical direction loads acting on top brackets provided at the upper end portions of the left and right vibration damping units 70, respectively.
Fig. 9 is a flowchart showing toe correction control of the suspension device according to embodiment 1.
Hereinafter, the description will be made in order of each step.
< step S01: obtaining steering wheel angle thetas >
The toe correction control unit 140 acquires the steering wheel angle θ s from the EPS control unit 110.
Then, the process proceeds to step S02.
< step S02: calculating steering speed thetas' >
The toe correction control unit 140 calculates the steering speed θ S' by time-differentiating the steering wheel angle θ S acquired in step S01.
Then, the process proceeds to step S03.
< step S03: judging vehicle speed >
The toe correction control unit 140 acquires the vehicle speed V from the motion control unit 120.
When the current vehicle speed V is equal to or lower than the preset upper limit vehicle speed Vmax and equal to or higher than the lower limit vehicle speed Vmin, it is determined that the vehicle speed V falls within the vehicle speed range in which the toe angle correction control should be executed, and the routine proceeds to step S04.
Otherwise, it is determined that the vehicle speed falls within a vehicle speed range in which the toe correction control should not be executed, and the series of processing (return) is ended.
< step S04: judgment steering start judgment flag
When the flag value of the steering start determination flag is 0, toe correction control section 140 proceeds to step S05 to determine whether steering is started.
If the value of the steering start determination flag is 1, it is considered that steering has already started, and the process proceeds to step S09.
< step S05: judging interference >
When the product of the steering angle θ S obtained in step S01 and the driver input torque Ts obtained from the EPS control unit 110 is equal to or greater than a predetermined threshold value, the toe correction control unit 140 assumes that the driver has made a purposeful steering operation, and proceeds to step S06.
In other cases, even if the steering wheel angle θ s or the like changes, it is determined that the disturbance is caused, and the series of processing is terminated (return).
< step S06: judging steering speed absolute value >
The toe correction control unit 140 compares the absolute value of the steering speed θ S' calculated in step S02 with a threshold value set in advance.
If the absolute value of the steering speed θ S' is equal to or greater than the threshold value, the process proceeds to step S07, and otherwise, the series of processes ends (return).
< step S07: judging the positive rotation and gyration
When the product of the steering wheel angle θ S obtained in step S01 and the steering speed θ S 'calculated in step S02 is positive (greater than 0), the toe correction control unit 140 determines that the steering angle is in the positive rotation in which the steering angle is increased by the driver' S operation (i.e., the cut り is increased by し), and proceeds to step S08.
On the other hand, in other cases, it is determined that the steering angle is decreasing (cut り し), and the series of processing ends.
< step S08: setting steering start judgment flag
The toe correction control unit 140 changes the flag value of the steering start determination flag from 0 to 1, thereby setting the flag.
Then, the process proceeds to step S09.
< step S09: drive force correction control
The toe correction control unit 140 instructs the drive control unit 130 to perform drive force correction control.
The driving force correction control increases the driving force of the turning outer wheel so as to turn in the toe-in direction in accordance with the wheel center rear tow characteristic, and decreases the driving force of the turning inner wheel so as to turn in the toe-in direction.
Then, the process proceeds to step S10.
< step S10: detecting a change in travel
The toe correction control unit 140 detects the stroke of the left and right vibration damping units 70 using the stroke sensor 141.
Then, the process proceeds to step S11.
< step S11: judging outer wheel side stroke >
When the amount of change in the stroke of the vibration damping unit 70 on the turning outer wheel side from the time of straight forward is equal to or greater than a predetermined threshold value, the toe correction control unit 140 determines that the toe of the outer wheel is sufficiently toe-in and the toe of the inner wheel is changed according to the lateral force steer-by-wire characteristic and the pitch steer characteristic, and proceeds to step S12.
In other cases, it is determined that the toe correction control needs to be continued, and the series of processes is terminated (return).
< step S12: clear steering start judgment flag
Toe correction control section 140 sets the flag value of the steering start determination flag to 0 and clears it, and the process proceeds to step S13.
< step S13: end drive force correction >
The toe correction control unit 140 ends the driving force correction, and ends a series of processes.
Fig. 10 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 1.
The vertical axis represents the toe angle of the turning outer wheel, and the upper side represents the toe side.
The horizontal axis represents the time counted from the start of steering.
Note that recording in the case where the driving force correction control is not performed is shown by a broken line, and recording in the case where the driving force correction control is performed is shown by a solid line.
Although the toe-in and toe-out are reversed on the turning inner wheel side, substantially the same record is shown.
In the case where the driving force correction control is not performed, the toe angle of the rear wheels is first changed toward the toe-behind direction in accordance with the vertical force steer characteristic, and when a stroke change and/or a lateral force of the suspension is thereafter generated, the toe-ahead side is changed in accordance with the bump steer characteristic and the lateral force steer characteristic.
In contrast, according to embodiment 1, by the above-described driving force correction control, the toe-in-side toe-in angle change can be temporarily generated at the initial stage of turning, and the temporary steering to the toe-in-side can be prevented, thereby improving the driving stability.
In addition, on the turning inner wheel side, it is likewise possible to prevent the temporary turning to the front beam side before the turning to the rear beam side.
(Example 2)
Next, embodiment 2 of the suspension device to which the present invention is applied will be described.
In each of the embodiments described below, the same reference numerals are used for the same elements as those in the previous embodiments, and the description thereof will be omitted, and the points of difference will be mainly described.
The suspension device according to embodiment 2 is a device that cancels out the effect of the vertical force steer-by-wire according to the drive force correction control of the right and left rear wheels, as in embodiment 1, and is characterized in that in order to suppress a sudden toe angle change caused by the switching of the drive force control, a drive force correction amount is set in accordance with the top bracket load, and the drive force correction amount at the end of the correction is changed slowly.
Fig. 11 is a flowchart showing toe correction control of the suspension device according to embodiment 2.
Hereinafter, the description will be made in order of each step.
< step S01: obtaining steering wheel angle thetas >
The toe correction control unit 140 acquires the steering wheel angle θ s from the EPS control unit 110.
Then, the process proceeds to step S02.
< step S02: calculating steering speed thetas' >
The toe correction control unit 140 calculates the steering speed θ S' by time-differentiating the steering wheel angle θ S acquired in step S01.
Then, the process proceeds to step S03.
< step S03: judging vehicle speed >
The toe correction control unit 140 acquires the vehicle speed V from the motion control unit 120.
When the current vehicle speed V is equal to or lower than the preset upper limit vehicle speed Vmax and equal to or higher than the lower limit vehicle speed Vmin, it is determined that the vehicle speed V falls within the vehicle speed range in which the toe angle correction control should be executed, and the routine proceeds to step S04.
Otherwise, it is determined that the vehicle speed falls within the vehicle speed range in which the toe correction control should not be executed, and the process proceeds to step S09.
< step S04: judgment steering start judgment flag
When the flag value of the steering start determination flag is 0, toe correction control section 140 proceeds to step S05 to determine whether steering is started.
If the value of the steering start determination flag is 1, it is considered that steering has already started, and the process proceeds to step S10.
< step S05: interference judgment >
When the product of the steering angle θ S obtained in step S01 and the driver input torque Ts obtained from the EPS control unit 110 is equal to or greater than a predetermined threshold value, the toe correction control unit 140 assumes that the driver has made a purposeful steering operation, and proceeds to step S06.
In other cases, even if the steering wheel angle θ S or the like changes, it is determined that the disturbance is caused, and the process proceeds to step S09.
< step S06: judging steering speed absolute value >
The toe correction control unit 140 compares the absolute value of the steering speed θ S' calculated in step S02 with a threshold value set in advance.
When the absolute value of the steering speed θ S' is equal to or greater than the threshold value, the process proceeds to step S07, and otherwise, the process proceeds to step S09.
< step S07: judging the positive rotation and gyration
When the product of the steering wheel angle θ S obtained in step S01 and the steering speed θ S 'calculated in step S02 is positive (greater than 0), the toe correction control unit 140 determines that the steering angle is increasing in the normal direction according to the driver' S operation, and proceeds to step S08.
On the other hand, in other cases, it is determined that the steering angle is being reduced, and the process proceeds to step S09.
< step S08: setting steering start judgment flag
The toe correction control unit 140 changes the flag value of the steering start determination flag from 0 to 1, thereby setting the flag.
Then, the process proceeds to step S10.
< step S09: storing top stent load >
The toe correction control unit 140 stores the current top-mount load detected by the top-mount load sensor 142 (F0).
Then, the series of processes ends (return).
< step S10: judge foreign wheel journey sign
The toe correction control means 140 proceeds to step S11 when the flag value of the outer wheel stroke flag, which is a flag indicating whether or not the outer wheel side vibration damping means 70 is stroked, is 0, and proceeds to step S17 otherwise.
< step S11: obtaining Top Stent load
The toe correction control unit 140 obtains the current top bracket load of the vibration damping unit 70 on the outer wheel side from the top bracket load sensor 142.
Then, the process proceeds to step S12.
< step S12: judging outer wheel stroke >
When the stroke change amount from the straight-ahead state of the outer wheel detected by the stroke sensor 141 is smaller than a preset threshold value, the toe correction control means 140 determines that the toe correction control is necessary, and proceeds to step S13, and otherwise, proceeds to step S16 to end the toe correction control.
< step S13: drive force correction control
The toe correction control unit 140 instructs the drive control unit 130 to perform drive force correction control.
The driving force correction control increases the driving force of the turning outer wheel so as to turn in the toe-in direction in accordance with the wheel center rear tow characteristic, and decreases the driving force of the turning inner wheel so as to turn in the toe-in direction.
At this time, the driving force increase amount on the outer wheel side and the driving force decrease amount on the inner wheel side fluctuate according to the top mount load.
Fig. 12 is a graph showing the relationship between the top bracket load and the driving force correction amount in the suspension device of embodiment 2.
As shown in fig. 12, the driving force correction amount is set to increase corresponding to an increase in the top-mount load.
Then, the process proceeds to step S14.
< step S14: storage correction amount >
The toe correction control unit 140 stores a correction amount γ according to the driving force correction currently being performed.
Then, the process proceeds to step S15.
< step S15: storage time index
The toe correction control unit 140 stores the current time as a time index t 0.
Then, the series of processes ends (return).
< step S16: setting outer wheel stroke mark
The toe correction control unit 140 sets the flag value of the outer wheel stroke flag to 1, thereby setting the flag.
Then, the process proceeds to step S17.
< step S17: obtaining a time index
The toe correction control unit 140 acquires the current time as the time index t.
Then, the process proceeds to step S18.
< step S18: calculating a correction value >
The toe angle correction control unit 140 calculates a correction amount of the driving force correction (outer wheel driving force increase amount, inner wheel driving force decrease amount) by the following expression 1.
Correction value γ F ((T-T0)/T) (formula 1)
Here, f (x) is a function set to gradually decrease the correction amount.
Fig. 13 is a graph showing the change in the driving force correction amount at the end of the normalized driving force correction in the suspension device according to embodiment 2.
As shown in fig. 13, the function f (x) is a function in which the normalized correction amount is gradually changed from 1 to 0 in accordance with the normalized time course (0 to 1).
T represents the time until the correction amount is gradually decreased to 0 finally.
Then, the process proceeds to step S19.
< step S19: corrected driving force >
The toe correction control unit 140 corrects the driving forces of the left and right rear wheels using the driving force correction amount calculated at step S19.
Then, the process proceeds to step S20.
< step S20: determining the correction end time >
The toe correction control unit 140 determines whether the driving force correction has substantially ended using the following expression 2.
T-T-T0 < 0 (formula 2)
When expression 2 is satisfied, it is considered that the driving force correction is substantially completed, and the series of processing is terminated (return).
On the other hand, if expression 2 is not satisfied, the process proceeds to step S21.
< step S21: clear steering start judgment flag
Toe correction control section 140 sets the flag value of the steering start determination flag to 0, and clears the flag.
Then, the process proceeds to step S22.
< step S22: end drive force correction >
The toe correction control unit 140 ends the driving force correction to step S23.
< step S23: clear outer wheel stroke sign
The toe correction control unit 140 sets the flag value of the outer wheel stroke flag to 0, and clears the flag.
Then, the series of processes ends.
Fig. 14 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 2.
In embodiment 2, the correction amount of the driving force correction is set to increase corresponding to the top mount load, and by gradually decreasing the correction amount at the end of the correction, it is possible to smooth the change of the toe angle, improve the driving stability, and reduce the sense of discomfort given to the driver.
(example 3)
Next, embodiment 3 of the suspension device to which the present invention is applied will be described.
The suspension device of embodiment 3 is a device that eliminates the influence of vertical force steer in the initial stage of turning by replacing the driving force difference of the left and right rear wheels of embodiment 1 with the braking force difference of the left and right rear wheels.
Such a braking force difference can be generated using the motion control unit 120 and the HCU 123.
Fig. 15 is a flowchart showing toe correction control of the suspension device according to embodiment 3.
As shown in fig. 15, in embodiment 3, the aspect of the braking force correction control of increasing the braking force of the outer wheel (generating the braking force in the case of no braking) and reducing the braking force of the inner wheel (not correcting in the case of no braking) in step 09, and the aspect of ending the braking force correction control in step S13 are different from the control of embodiment 1 shown in fig. 9.
Also in embodiment 3 as described above, substantially the same effect as that of embodiment 1 described above can be obtained.
Note that in embodiment 3, the braking force correction amount may be set to increase in accordance with the top mount load substantially similarly to the driving force correction amount of embodiment 2, and at the end of the braking force correction, the braking force correction amount may be changed slowly.
In this case, substantially the same effect as that of embodiment 2 described above can be obtained.
(example 4)
Next, embodiment 4 of the suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 4 is a device that eliminates the influence of vertical force compliant steering at the initial stage of turning using a 4-wheel steering (4WS) system that steers the rear wheels in accordance with the driver.
Fig. 16 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 4.
The suspension control system of embodiment 4 has a 4WS control unit 230 instead of the drive control unit 130 and the like of embodiment 1.
The 4WS control unit 230 controls a 4WS motor 231 as an electric actuator that forcibly changes (steers) the toe angles of the left and right rear wheels.
Fig. 17 is a flowchart showing toe correction control of the suspension device according to embodiment 4.
As shown in fig. 17, in embodiment 4, toe correction control is performed in which the outer wheel is steered toward the toe-in side and the inner wheel is steered toward the toe-out side in step S09, and the toe correction control is ended in step S13, which is different from the control of embodiment 1 shown in fig. 9.
In embodiment 4 as described above, by performing the toe correction control of the outer wheel turning to the toe-in side and the inner wheel turning to the toe-in side using the 4WS system in the initial stage of turning, it is possible to prevent the outer wheel from turning to the toe-in side due to the vertical force flexible steering, and improve the driving stability.
Note that in embodiment 4, the correction amount of the toe angle may be set to increase corresponding to the top mount load substantially similarly to the driving force correction amount of embodiment 2, and the toe angle correction amount may be made to change slowly at the end of the toe angle correction.
In this case, substantially the same effects as those of embodiment 2 described above can be obtained.
(example 5)
Next, embodiment 5 of a suspension device to which the present invention is applied will be described.
The suspension device of embodiment 5 is a device for eliminating the influence of vertical force compliant steering at the initial stage of turning using an adjustable damper that uses, as a working fluid, an MR (magnetorheological) fluid in which a magnetic field is applied from the outside to change the viscoelastic characteristics.
Fig. 18 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 5.
The suspension control system of embodiment 5 has a damping control unit 330 instead of the drive control unit 130 and the like of embodiment 1.
The damping control unit 330 controls the magnetic field applied to the dampers of the left and right damper units 70 to change the damping characteristics.
Fig. 19 is a flowchart showing toe correction control of the suspension device according to embodiment 5.
As shown in fig. 19, embodiment 5 is different from the control of embodiment 1 shown in fig. 9 in that the damping force correction control for reducing the damping force of the outer wheel side shock absorber is performed in step S09, and the damping force correction control is ended in step S13.
Fig. 20 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 5.
Without the damping force correction control, the toe angle of the rear wheels is first changed to the rear toe direction in accordance with the vertical force steer characteristics, and then changed to the front toe side in accordance with the bump steer characteristics and the lateral force steer characteristics when the stroke change of the suspension and/or the lateral force are generated.
When the damping force correction control is performed, the damper damping force of the turning outer wheel is reduced, thereby promoting the initial stroke of the damper unit 70, enabling the pitch steering characteristic to be generated at an early stage, shortening the period in which the influence of the vertical force compliant steering characteristic is exhibited, and improving the driving stability.
(example 6)
Next, embodiment 6 of the suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 6 is an active suspension capable of forcibly extending and contracting the damper stroke, and the effect of vertical force compliant steering at the initial stage of turning is eliminated by controlling the damper stroke.
Fig. 21 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 6.
The suspension control system of embodiment 6 has a damper stroke control unit 430 instead of the drive control unit 130 and the like of embodiment 1.
The damper stroke control unit 430 controls the stroke by controlling an actuator that extends and contracts the dampers of the left and right damper units 70.
Fig. 22 is a flowchart showing toe correction control of the suspension device according to embodiment 6.
As shown in fig. 22, in embodiment 6, stroke correction control for shortening the stroke of the outer wheel side shock absorber is performed in step S09, and the control for ending the stroke correction control in step S13 is different from the control of embodiment 1 shown in fig. 9.
Further, the top stand load of the vibration damping unit 70 is detected in step S10, and if the top stand load is larger than the threshold value in step S11, the routine proceeds to step S12, and otherwise the process ends (returns).
In example 6 as described above, the stroke of the outer wheel side damper is forcibly shortened at the initial stage of turning, so that the bump steering can be generated at an early stage, and the phenomenon that the outer wheel is steered to the toe-in side by the vertical force soft steering can be prevented, thereby improving the driving stability.
(example 7)
Next, embodiment 7 of the suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 7 is a device that has a head bracket that is expandable and contractible in the axial direction of a shock absorber by being filled with a fluid such as air, and that eliminates the effect of vertical force flexible steering at the initial stage of turning by controlling the head bracket.
Fig. 23 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 7.
The suspension control system of embodiment 7 has a top bracket control unit 530 instead of the drive control unit 130 and the like of embodiment 1.
The top chassis control unit 530 controls air injection into the top chassis of the left and right damper units 70, thereby extending and contracting the top chassis in the axial direction of the damper.
Fig. 24 is a flowchart showing toe correction control of the suspension device according to embodiment 7.
As shown in fig. 24, in embodiment 7, the stroke correction control for extending the stroke is performed by injecting air into the outer wheel side top carrier in step S09, and the aspect of ending the stroke correction control in step S13 is different from the control of embodiment 1 shown in fig. 9.
Fig. 25 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 7.
Without performing the stroke correction control, the toe angle of the rear wheels is first changed to the toe-behind direction in accordance with the vertical force steer characteristic, and when a stroke change and/or a lateral force of the suspension is generated thereafter, the toe-ahead side is changed in accordance with the bump steer characteristic and the lateral force steer characteristic.
When the stroke correction control is performed, the top bracket is extended at the initial stage of turning, the input load to the damper is increased, the locking of the damper unit 70 is released at an early stage, and the initial stroke is promoted, so that the jerk steering characteristic is generated at an early stage, and the period in which the influence of the vertical force flexible steering characteristic is exerted can be shortened, and the driving stability can be improved.
(example 8)
Next, embodiment 8 of a suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 8 is a device in which the stabilizer 80 is an adjustable stiffness stabilizer capable of changing roll stiffness, and the influence of vertical force compliant steering at the initial stage of turning is eliminated in accordance with roll stiffness control.
Fig. 26 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 8.
The suspension control system of embodiment 8 has an adjustable stabilizer control unit 630 instead of the drive control unit 130 and the like of embodiment 1.
The adjustable stabilizer control unit 630 controls an unillustrated actuator provided in the stabilizer 80 to change the roll rigidity.
Fig. 27 is a flowchart showing toe correction control of the suspension device according to embodiment 8.
As shown in fig. 27, in embodiment 8, roll rigidity correction control for reducing (softening) the roll rigidity is performed in step S09, and in step S13, the roll rigidity correction control is ended differently from the control of embodiment 1 shown in fig. 9.
Fig. 28 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 8.
The change in the toe angle of the rear wheel in the case where the roll rigidity is stably kept low is shown by a two-dot chain line in fig. 28.
Without roll rigidity correction control, the toe angle of the rear wheel is first changed to the toe-behind direction in accordance with the vertical force steer characteristic, and when a stroke change and/or a lateral force of the suspension is generated thereafter, the toe-ahead side is changed in accordance with the jounce steer characteristic and the lateral force steer characteristic.
When roll stiffness correction control is performed, roll stiffness is reduced at the initial stage of turning to promote roll of the vehicle body, and the lock of the vibration damping unit 70 is released at an early stage to promote an initial stroke, so that the jerk steering characteristic is generated at an early stage, and a period in which the influence of the vertical force buckling steering characteristic is exerted can be shortened to improve the driving stability.
Further, after the bump steering and the lateral force compliant steering are sufficiently generated, the roll rigidity is returned to the initial state, thereby improving the driving stability.
(example 9)
Next, embodiment 9 of a suspension device to which the present invention is applied will be described.
In the suspension device according to embodiment 9, the stabilizer device 80 is an active stabilizer that can generate a moment in the roll direction of the vehicle by dividing the stabilizer bar in the intermediate portion and applying a torque in the torsion direction.
In embodiment 9, the influence of the vertical force flexible steering at the initial stage of turning is eliminated by controlling the active stabilizer.
Fig. 29 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 9.
The suspension control system of embodiment 9 has an active stabilization control unit 730 instead of the drive control unit 130 and the like of embodiment 1.
The active stabilization control unit 730 controls an actuator, not shown, provided in the stabilizer 80 to control the relative twisting of the right and left stabilizer bars.
Fig. 30 is a flowchart showing toe correction control of the suspension device according to embodiment 9.
As shown in fig. 30, in embodiment 9, the stabilizer bar torsion control is performed in accordance with the active stabilizer in step S09 so as to promote the rolling action in the direction in which the outer wheel side jumps, and the stabilizer bar torsion control is ended in step S13 differently from the control of embodiment 1 shown in fig. 9.
In embodiment 9 described above, by substantially forcibly generating the roll using the active stabilizer and causing the suspension to stroke, it is possible to generate the bump steering at an early stage, prevent the outer wheel from being steered to the toe-out side in accordance with the vertical force compliant steering, and improve the driving stability.
(example 10)
Next, embodiment 10 of a suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 10 includes, in the vehicle body side rubber bushings of the front transverse link 30 and the rear transverse link 40, adjustable rigid rubber bushings capable of changing the elastic constant (the adjustable rigid bushings are liquid-tight bushings that enclose MR fluid whose viscoelastic characteristics change when a magnetic field is applied from the outside, and the elastic constant can be changed depending on the state of application of the magnetic field), and the vertical force flexible steering characteristics are inverted by controlling the elastic constant.
Fig. 31 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 10.
The suspension control system of embodiment 10 has a sleeve rigidity control unit 830 instead of the drive control unit 130 and the like of embodiment 1.
The sleeve rigidity control unit 830 controls the elastic constant of the vehicle body-side rubber sleeve of the front cross link 30.
Fig. 32 is a flowchart showing toe correction control of the suspension device according to embodiment 10.
As shown in fig. 32, in embodiment 10, control is performed to increase the elastic constant of the rubber bushings of the front transverse link 30 on the outer wheel side and the inner wheel side in step S09, and in step S13, the aspect of ending the elastic constant control is different from the control of embodiment 1 shown in fig. 9.
Fig. 33 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 10.
In embodiment 10, by performing the above-described elastic constant control of the bushings of the front transverse link 30, the difference in rigidity between the rubber bushings of the front transverse link 30 and the rubber bushings of the rear transverse link 40 is reversed between the initial stage of turning and the other stages.
As a result, in example 10, the vertical force flexible steering characteristic can be inverted as compared with the case where such control is not performed.
Therefore, according to embodiment 10, it is possible to prevent the outer wheel from turning to the toe-in side and the inner wheel from turning to the toe-in side at the initial stage of turning, and improve the driving stability.
It should be noted that substantially the same effect can be obtained by temporarily decreasing the spring constant of the bushing of the rear transverse link 40 instead of temporarily increasing the spring constant of the bushing of the front transverse link 30, or temporarily increasing the spring constant of the bushing of the front transverse link 30 and temporarily decreasing the spring constant of the bushing of the rear transverse link 40.
(example 11)
Next, embodiment 11 of a suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 11 includes an adjustable rigid top bracket capable of changing its spring constant at the top bracket of the upper end portion of the damper unit 70, and reduces the influence of vertical force flexible steering by controlling the spring constant.
Fig. 34 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 11.
The suspension control system of embodiment 11 has a top bracket rigidity control unit 930 instead of the drive control unit 130 and the like of embodiment 1.
The top bracket rigidity control unit 930 controls the spring constant of the top bracket of the damping unit 70.
Fig. 35 is a flowchart showing toe correction control of the suspension device according to embodiment 11.
As shown in fig. 35, in embodiment 11, control is performed to increase the elastic constants of the outer wheel side and the inner wheel side top stays in step S09, and the aspect of ending the elastic constant control in step S13 is different from the control of embodiment 1 shown in fig. 9.
Fig. 36 is a graph schematically showing an example of a change in the toe angle of the rear wheel of the suspension device according to embodiment 11.
In example 11, by performing the spring constant control of the top bracket, the initial input to the vibration damping unit 70 is increased, and the locking of the vibration damping unit 70 is released at an early stage to promote the initial stroke, so that the jerk steering characteristic is generated at an early stage, and the period in which the influence of the vertical force flexible steering characteristic is exerted can be shortened to improve the driving stability.
(example 12)
Next, embodiment 12 of a suspension device to which the present invention is applied will be described.
The suspension device according to embodiment 12 reduces the influence of vertical force buckling by changing the spring constant of a part of the bushings (toe-in side specific bushings) that can rotate the bracket 20 to the toe-in side and a part of the bushings (toe-in side specific bushings) that can rotate the bracket 20 to the toe-in side by changing the spring constant (increasing or decreasing) among the bushings provided at the end portions of the front transverse link 30, the rear transverse link 40, the upper link 50, and the vertical link 60.
Such a change in the elastic constant of the sleeve can be achieved by using a liquid-sealed sleeve or the like in which an MR fluid that changes its viscoelastic characteristics by applying a magnetic field is sealed.
Fig. 37 is a block diagram showing a configuration of a control system of a suspension device according to embodiment 12.
The suspension control system of embodiment 12 has a sleeve rigidity control unit 1030 instead of the drive control unit 130 and the like of embodiment 1.
The sleeve rigidity control unit 1030 controls the elastic constants of the toe-side specific sleeve and the toe-side specific sleeve.
Fig. 38 is a flowchart showing toe correction control of the suspension device according to embodiment 12.
As shown in fig. 38, in embodiment 12, control is performed to change the elastic constant of the toe-in side specifying bush on the turning outer wheel side and the toe-out side specifying bush on the turning inner wheel side in step S09, and the control to end the change in the elastic constant in step S13 is different from the control of embodiment 1 shown in fig. 9.
Fig. 39 is a graph schematically showing an example of a change in the toe angle of the rear wheel in the suspension device according to embodiment 12.
In example 12, the bracket 20 is rotated from the turning outer wheel side to the toe-in side to the turning inner wheel side to the toe-out side by the rigidity control of the link bush, whereby the influence of the vertical force flexible steering can be suppressed and the driving stability can be improved.
(modification example)
The present invention is not limited to the embodiments described above, and various modifications and/or changes can be made, which fall within the technical scope of the present invention.
(1) The configuration of the suspension device is not limited to the above-described embodiment, and may be appropriately changed. For example, the form of the suspension device is not limited to the double wishbone type as in the embodiment, and may be other forms such as a column type, a multi-link type, and a trailing arm type. The configuration of the control system is not particularly limited.
(2) In embodiments 1 and 2, the driving force difference is generated in the right and left rear wheels by the motor that applies driving force to the right and left rear wheels alone, but the present invention is not limited to this, and the driving force difference may be generated by another method.
For example, the output of the electric motors that drive the engine and/or the right and left rear wheels together may be distributed by a torque vector distribution device that changes the torque distribution of the right and left rear wheels to transmit to generate the driving force difference.
(3) The toe angle control according to the driving force difference as in embodiments 1, 2 and the toe angle control according to the braking force difference as in embodiments 3, 4 may be used in combination.
For example, in the case of a suspension device having a tow-toe-behind characteristic, a driving force may be applied to the outer wheel and a braking force may be applied to the inner wheel.
(4) Although the suspension devices having the wheel center rear-toe-behind-toe characteristic are all the embodiments 1 to 4, the present invention can be applied to a suspension device having the wheel center rear-toe-behind-toe characteristic. In this case, the control contents of the inner wheel and the outer wheel may be reversed.
(5) Each embodiment ends the toe correction control based on the shock absorber stroke, the top mount load, and the like, but is not limited thereto, and the toe correction control may also be ended by another method. For example, the control may be ended at a predetermined time after the turning is started. The method for changing the control amount slowly is not particularly limited.
(6) In each of the embodiments, the braking force difference is generated in the left and right rear wheels by the motor that applies braking force to the left and right rear wheels alone, but the present invention is not limited to this, and the left and right braking force difference may be generated by brake control such as ESC. In this case, since a braking force acts on the ground point, the control content is changed according to the toe angle change characteristic of the trailing behind ground point. For example, since the suspension device 1 has the ground contact point rear-to-front-toe characteristic, by increasing the braking force of the turning outer wheel, it is possible to suppress the rear toe caused by the vertical force steering at the initial stage of turning.

Claims (2)

1. A suspension device is characterized by comprising:
a hub bearing bracket that supports a rear wheel of a vehicle so that the rear wheel of the vehicle can rotate around an axle;
a suspension link having both ends swingably attached to a vehicle body and a hub bearing bracket, respectively, and supporting the hub bearing bracket to allow a stroke relative to the vehicle body;
a suspension spring that generates a reaction force corresponding to a relative displacement amount of the hub bearing bracket with respect to a vertical direction of the vehicle body; and
a damper that generates a damping force corresponding to a relative speed of the hub bearing bracket with respect to a vertical direction of the vehicle body,
and the suspension device has a vertical force flexible steering characteristic of steering the rear wheel to a toe-in side or a toe-out side in accordance with an increase in a vertical force acting on a tread of the rear wheel,
the suspension device further includes a toe-angle change generation means for temporarily generating a toe-angle change in an initial turning stage of the vehicle in a direction to cancel or suppress the toe-angle change caused by the vertical-force steer-by-wire characteristic,
the toe-angle-change generating unit has a support rigidity control unit that temporarily increases rigidity of an adjustable rigid elastic body support provided between an upper end portion of the shock absorber and a vehicle body at an initial stage of turning.
2. The suspension device according to claim 1,
the support rigidity control unit restores the rigidity of the adjustable rigidity elastic body support to a state before the start of turning, in accordance with the stroke of the shock absorber reaching a predetermined value or more.
CN201710821816.4A 2013-03-28 2014-03-28 Suspension device Active CN107719052B (en)

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JP2013070097A JP6087696B2 (en) 2013-03-28 2013-03-28 Suspension device
CN201410130829.3A CN104070954B (en) 2013-03-28 2014-03-28 Draft hitch

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