JP4941416B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a vehicle suspension system including a device that controllably generates a force for moving an upper spring portion and an lower spring portion close to and away from each other by an operation of an electromagnetic motor.

In recent years, as a suspension system for a vehicle, a device that generates a force (hereinafter sometimes referred to as “approaching and separating force”) that moves the spring upper part and the spring lower part closer to and away from each other based on the force of an electromagnetic motor. A suspension system provided with a certain approach / separation force generator corresponding to each wheel has been studied. A system including such a device is expected as a high-performance system because vibration damping characteristics based on the so-called skyhook damper theory can be easily realized. In addition, a technique related to vibration damping based on the Skyhook damper theory is described in the following patent document, and by applying such a technique to a system including the approaching / separating force generating device, the performance of the system is further improved. Is expected.
Japanese Patent Laid-Open No. 7-117433 JP-A-5-201224 JP-A-5-201230

  In the suspension system including the approaching / separating force generating device described above, when the approaching / separating force is generated so as to attenuate the sprung vibration generated in the vehicle body, the approaching / separating force is not limited to the upper part of the spring but the lower part of the spring. Therefore, although the sprung vibration is attenuated, it affects the grounding property of the wheel. The suspension system provided with the approaching / separating force generator is still under development, has various problems including the above problems, and leaves much room for improvement. Therefore, it is considered that the practicality of the suspension system is improved by various improvements. The present invention has been made in view of such circumstances, and an object thereof is to provide a highly practical suspension system.

  In order to solve the above-described problems, in the vehicle suspension system of the present invention, at least a part of the approaching / separating force generated by the approaching / separating force generating device is a damping force against the vibration of the upper part of the spring corresponding to the sprung speed. When the sprung vibration damping control is performed, and when the sprung vibration damping control is executed, the movement direction of the sprung portion and the movement direction of the unsprung portion are different from each other. An unsprung displacement increasing control is performed to act as a force that increases the unsprung displacement having a magnitude corresponding to the unsprung displacement amount.

  Depending on the direction of the approaching / separating force generated by the approaching / separating force generating device, the vertical movement of the unsprung part according to the undulation of the road surface is obstructed by the approaching / separating force, and the followability to the road surface of the unsprung part decreases. Wheel grounding may be reduced. In the suspension system of the present invention, when the approaching / separating force generated in the sprung vibration damping control hinders the operation of the unsprung part, the operation of the unsprung part can be promoted. Therefore, according to the system of the present invention, even when the operation of the unsprung portion is hindered by the approaching / separating force, it is possible to prevent a decrease in followability of the unsprung portion to the road surface, and the grounding property of the wheel Can be suppressed.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. In the following items, items (1) to (11) correspond to claims 1 to 11, respectively.

(1) a suspension spring that elastically connects the sprung portion and the unsprung portion;
An approaching / separating force generating device that has an electromagnetic motor and generates an approaching / separating force that is a force for approaching / separating the sprung portion and the unsprung portion based on the force generated by the electromagnetic motor;
A vehicle suspension system comprising: a control device that controls an approaching / separating force generated by the approaching / separating force generating device by controlling an operation of the electromagnetic motor;
The control device is
A sprung vibration damping control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part of the approach / separation force becomes a damping force with respect to the vibration of the sprung portion having a magnitude corresponding to the sprung speed;
When the control by the sprung vibration damping control unit is executed, the approaching / separating force generated by the approaching / separating force generator is different from the approaching / separating force generating device when the direction of the operation of the sprung portion is different from the direction of the operation of the unsprung portion. A suspension system for a vehicle, comprising: an unsprung displacement increase control unit that controls the portion to have a force that increases the unsprung displacement according to the unsprung displacement amount.

  The approaching / separating force generated by the approaching / separating force generating device acts not only on the upper part of the spring but also on the unsprung part. Therefore, the direction in which the approaching / separating force is generated (hereinafter referred to as “approaching / separating force generation direction”). In some cases, the grounding performance of the wheel may be reduced. More specifically, for example, when the approaching / separating force generation direction is a direction in which the spring upper part and the spring unsprung part approach each other, when the spring lower part moves downward according to the undulation of the traveling road surface, the spring is moved by the approaching / separating force. The downward movement of the lower part is obstructed, and the characteristics that the lower part of the spring tends to operate according to the undulation of the road surface, that is, the followability of the lower part of the spring to the road surface is reduced, so that the grounding property of the wheel may be reduced. . On the other hand, when the approaching / separating force generation direction is a direction separating the spring upper part and the spring unsprung part, when the spring lower part moves upward according to the undulation of the traveling road surface, the approaching / separating force causes the upper part of the spring lower part to move upward. Since the movement to the wheel is hindered, there is a possibility that the grounding property of the wheel is lowered. Thus, when the movement of the unsprung portion is hindered by the approaching / separating force, there is a possibility that the grounding property of the wheel is lowered.

  For example, when the approaching / separating force acts as a damping force against the sprung vibration, when the upper part of the spring moves upward, the approaching / separating force generation direction is a direction in which the upper part of the spring and the unsprung part are brought closer to each other. When the upper part moves downward, the approaching / separating force generation direction is a direction in which the spring upper part and the spring lower part are separated from each other. Therefore, when the unsprung part moves upward and the unsprung part moves downward, and when the unsprung part moves downward and the unsprung part moves upward, the approaching and separating are performed. The action of the unsprung portion is hindered by the force, and there is a possibility that the grounding property of the wheel may be lowered. That is, when the direction of the operation of the sprung portion and the direction of the operation of the unsprung portion are different from each other, there is a possibility that the grounding property of the wheel is deteriorated.

  In view of the above, in the suspension system according to the aspect described in this section, when the sprung vibration damping control is executed, if the direction of the motion of the sprung portion and the direction of the motion of the sprung portion are different from each other, In order to suppress the deterioration of the performance, a part of the approaching / separating force is used as a force to increase the displacement of the unsprung portion corresponding to the unsprung displacement amount so that the unsprung portion follows the vertical displacement of the road surface. It is acting. That is, a part of the approaching / separating force acts as a force that cancels the fluctuation of the spring force caused by the displacement of the unsprung portion, thereby promoting the displacement of the unsprung portion and facilitating the displacement of the unsprung portion. Therefore, according to the system of the aspect described in this section, it is possible to prevent the followability of the unsprung portion to the road surface from being lowered, and it is possible to suppress the decrease in the ground contact performance of the wheel. The “unsprung displacement amount” described in this section is the amount of displacement in the vertical direction from a specific reference position of the unsprung portion, for example, the spring when the vehicle is stationary on a flat road. This is the amount of vertical displacement from the specific position when the lower position is the specific position.

  The configuration of the “approaching / separating force generator” described in this section is not particularly limited. For example, as will be described later, an elastic body connected to the unsprung portion and an elastic body fixed to the vehicle body. And a deformable actuator, and the force generated by the actuator is applied to the elastic body, and the force is generated as an approaching / separating force. That is, the approaching / separating force generating device can be a constituent element of a so-called left and right independent stabilizer device. Also, it has a sprung unit connected to the sprung part and a sprung unit connected to the sprung part, and the two units move relative to each other as the sprung part and the sprung part approach and separate. It is possible to adopt a configuration in which the force can be expanded and contracted, and a force in the direction of relative movement of the two units is generated depending on the force generated by the electromagnetic motor, and the force acts as an approaching / separating force. That is, a so-called electromagnetic shock absorber may be employed as the approaching / separating force generator.

  The approaching / separating force generating device is, for example, a force that actively moves the sprung portion and the unsprung portion relative to each other, that is, a propulsive force or a force that prevents the sprung portion and the unsprung portion from moving relative to an external input. That is, it is possible to generate a maintenance force and a resistance force against the relative movement between the sprung portion and the unsprung portion. In addition to the above-described sprung vibration damping control, the control device also suppresses vehicle body posture changes for the purpose of suppressing vehicle body roll due to vehicle turning and vehicle body pitch due to vehicle acceleration / deceleration. It is possible to configure such that control or the like is also executed.

(2) The vehicle suspension system includes a hydraulic shock absorber that generates a damping force that attenuates the relative vibrations of the upper and lower spring parts.
The control device further comprises:
During the execution of the control by the unsprung displacement increase control unit, the approaching / separating force generated by the approaching / separating force generating device partly accelerates the operation of the unsprung portion having a magnitude corresponding to the unsprung speed. The vehicle suspension system according to the item (1), further including an unsprung acceleration control unit that controls the power to become force.

  When the ground contact property of the wheel is ensured by the unsprung displacement increase control, vibration input from the unsprung portion tends to be transmitted to the unsprung portion, which may adversely affect the riding comfort of the vehicle. Further, in a system provided with a hydraulic shock absorber, vibrations input from the lower part of the spring are easily transmitted to the upper part of the spring. That is, the damping force generated by the absorber acts on the sprung portion and the unsprung portion, so that vibration is easily transmitted to the sprung portion. In the system described in this section, when the unsprung displacement increase control is executed, a part of the damping force generated by the absorber is canceled by increasing the vertical movement of the unsprung portion. Therefore, according to the system described in this section, when the unsprung displacement increase control is executed, for example, it is possible to reduce the transmission of vibrations to the sprung portion, and to ensure the riding comfort of the vehicle. Is possible.

(3) The shock absorber has a damping coefficient changing mechanism that changes a damping coefficient that is a reference of a damping force generated by itself.
The unsprung acceleration control unit is
Only when the damping coefficient of the shock absorber is larger than a set threshold damping coefficient, the approaching / separating force generated by the approaching / separating force generating device becomes a force that accelerates the operation of the unsprung portion. The vehicle suspension system according to item (2), configured to control the separation force.

  The damping coefficient of the absorber is closely related to the transmission of vibration from the unsprung part to the unsprung part. The higher the damping coefficient of the absorber, the easier the vibration is transmitted to the sprung part. Therefore, according to the system described in this section, for example, even when the damping coefficient of the absorber is changed to a high damping coefficient, it is possible to reduce the transmission of vibration to the sprung portion. The ride comfort can be secured.

(4) The unsprung acceleration control unit is
The approaching / separating force generating device such that the magnitude of the force for accelerating the operation of the unsprung portion is a magnitude obtained by multiplying the value obtained by subtracting the set threshold damping coefficient from the damping coefficient of the shock absorber and the unsprung speed. The vehicle suspension system according to item (3), which is configured to control the approaching / separating force generated by the vehicle.

  By canceling a part of the damping force generated by the absorber by unsprung acceleration control, it is possible to reduce the damping force that acts on the lower part of the spring and make it difficult to transmit the vibration input from the lower part of the spring to the upper part of the spring. Is possible. However, if the damping force acting on the unsprung portion becomes too small, the grounding property of the wheel may be deteriorated. In the system described in this section, even when the unsprung acceleration control is executed, the damping force generated by the absorber when the absorber damping coefficient is set to the set threshold damping coefficient is applied to the lower part of the spring. It is possible to act. Therefore, according to the system described in this section, it is possible to reduce the transmission of vibration input from the unsprung portion to the unsprung portion while ensuring the grounding property of the wheel.

  (5) The vehicle suspension system according to (3) or (4), wherein the set threshold damping coefficient is set to a value that makes appropriate damping characteristics with respect to vibration at an unsprung resonance frequency.

  (6) The vehicle suspension system according to any one of (3) to (5), wherein the set threshold damping coefficient is set to 1000 N · sec / m or more and 2000 N · sec / m or less.

  The approaching / separating force generator is configured to change the approaching / separating force by controlling the operation of the electromagnetic motor. When the above-described sprung vibration damping control is executed due to problems such as the response of the electromagnetic motor. There is a high possibility that it is difficult to satisfactorily attenuate vibrations in a relatively high frequency range. For this reason, it is desirable to deal with vibration in a relatively high frequency range with an absorber. As described above, the damping coefficient of the absorber is related to the transmission of vibration from the unsprung part to the unsprung part. Roughly speaking, the lower the damping coefficient, the more the vibration in the higher frequency range is transmitted to the unsprung part. It becomes difficult to do. For this reason, when considering the transmission of vibrations in a relatively high frequency range, it is desirable that the damping coefficient of the absorber is low. However, the damping coefficient of the absorber is closely related to the grounding property of the wheel, and will be described in detail later. As the damping coefficient is lower, the grounding property of the wheel with respect to vibrations in a relatively high frequency range tends to decrease. In particular, when the damping coefficient is reduced to some extent, the grounding property of the wheel against vibrations in a relatively high frequency range tends to be considerably reduced. “1000 to 2000 N · sec / m” described in the latter term is a value of a damping coefficient that takes into account the balance between the transmission of relatively high frequency vibrations and the grounding property of a wheel against vibrations in a relatively high frequency range. Therefore, according to the system described in the latter section, for example, it is possible to suppress the transmission of vibrations in a relatively high frequency range to the sprung portion while ensuring the grounding property of the wheels to some extent.

  Most of the hydraulic type absorbers are designed to expand and contract with the approach and separation of the upper and lower parts of the spring and generate a damping force with a magnitude corresponding to the speed of expansion and contraction. It is arranged in between. Since the suspension arm pivots around its own end connected to the vehicle body, the closer the absorber is arranged to the end of the suspension arm on the vehicle body side, the lower the expansion / contraction speed becomes. The closer to the end of the arm on the wheel side, the higher the expansion / contraction speed. That is, even if the relative speeds of the sprung portion and the unsprung portion are the same, the expansion / contraction speed of the absorber varies depending on the position where the absorber is disposed, and the damping force generated by the absorber also varies depending on the position where the absorber is disposed. For this reason, the value of the damping coefficient of the absorber serving as a reference for the damping force generated by the absorber is set according to the position where the absorber is arranged, in other words, the position where the force generated by the absorber is applied. “1000 to 2000 N · sec / m” described in this section is a value when it is assumed that the body and the wheel are directly actuated in the vertical direction with respect to the approaching / separating operation of the sprung portion and the unsprung portion.

(7) The control device further includes:
A roll suppression control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part thereof is a force that suppresses the roll of the vehicle body caused by turning of the vehicle;
And a pitch suppression control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part thereof is a force that suppresses the pitch of the vehicle body caused by acceleration / deceleration of the vehicle. The vehicle suspension system according to any one of items (1) to (6).

  In the system described in this section, the approach / separation force is caused to act as at least one of the roll suppression force and the pitch suppression force, and at least one of the roll suppression control and the pitch suppression control is executed. The “force to suppress the roll” described in this section is to suppress the roll of the vehicle body by reducing the roll amount of the vehicle body caused by the turning of the vehicle, for example, due to the turning of the vehicle. It may be determined based on the roll moment received by the vehicle body. In addition, the “pitch suppressing force” described in this section suppresses the pitch of the vehicle body by reducing the pitch amount of the vehicle body caused by the acceleration / deceleration of the vehicle. It may be determined based on the pitch moment received by the vehicle body due to the above. When at least one of the roll suppression control and the pitch suppression control and the sprung vibration damping control are executed simultaneously, in addition to the approaching / separating force as a damping force for the vibration of the sprung portion, The approaching / separating force as at least one of the pitch suppression force is generated by the approaching / separating force generating device.

(8) The approaching / separating force generator is
An elastic body having one end connected to the unsprung portion;
The other end of the elastic body is held and fixed to the vehicle body, and the force generated by the electromagnetic motor is applied to the elastic body based on the force generated by the electromagnetic motor using the electromagnetic motor as a component of the electromagnetic motor. And an electromagnetic actuator that changes the amount of deformation of the elastic body in accordance with the amount of movement of the elastic body and applies the force to the spring upper part and the spring lower part via the elastic body. The vehicle suspension system according to any one of (7).

  In the system described in this section, the approach / separation force generating device is limited to one component of a so-called left and right independent type stabilizer device. The “approaching / separating force generator” described in this section is configured to apply a force generated by an actuator to an elastic body and to change a deformation amount of the elastic body according to an operation amount of the actuator. Therefore, in the system described in this section, the approaching / separating force generated by the approaching / separating force generating device and the operation amount of the actuator correspond to each other. The “elastic body” described in this section may be any elastic body that exhibits some elastic force in accordance with the amount of deformation. For example, it can be an elastic body having various structures such as a coil spring and a torsion spring. .

(9) The elastic body is connected to a shaft portion that is rotatably held by the actuator, and a wheel holding member that extends from one end portion of the shaft portion so as to intersect the shaft portion, and the tip portion holds the wheel. Arm and
The vehicle suspension system according to item (8), wherein the actuator rotates the shaft portion around an axis thereof by a force generated by the actuator.

  In the system described in this section, the structure of the approaching / separating force generator is more specifically limited. As for the “elastic body” in the aspect of this section, it is sufficient that at least one of the shaft portion and the arm portion has a function as an elastic body. For example, the shaft portion may be twisted so that it has a function as a spring, and the arm portion may be bent so that it has a function as a spring. Note that the elastic body may be a member in which the shaft portion and the arm portion are separate members, and may be formed by integrating them.

(10) The ratio of the external input to the force of the electromagnetic motor necessary for operating the actuator against the external input is set so that the actuator cannot be operated even by the positive efficiency of the actuator and the external input. When the ratio of the electromagnetic motor force required to the external input is defined as the product of the reverse efficiency of the actuator, the positive efficiency and the reverse efficiency, and the product of the normal and reverse efficiency, respectively,
The vehicle suspension system according to (8) or (9), wherein the actuator has a structure having a forward / reverse efficiency product of 1/2 or less.

  The “normal / reverse efficiency product” described in this section is necessary because the motor force required to operate the actuator against an external input of a certain magnitude and the actuator cannot be operated by the external input. It can be considered as a ratio to the motor force, and the smaller the forward / reverse efficiency product, the less the actuator is moved with respect to the external input. Therefore, if an actuator with a relatively small forward / reverse efficiency product is employed, for example, when restraining the roll, pitch, etc. of the vehicle body, the distance between the vehicle body and the wheel is maintained at a certain distance under the action of an external input. In some cases, the distance can be maintained with relatively little power. Therefore, according to the system described in this section, an excellent system can be realized from the viewpoint of power saving.

  (11) The actuator has a speed reducer that decelerates the operation of the electromagnetic motor, and the operation decelerated by the speed reducer becomes its own operation, and the reduction ratio of the speed reducer becomes 1/100 or less. The vehicle suspension system according to any one of items (8) to (10), which is structured.

  The system according to the aspect described in this section is a system that employs an actuator having a relatively large reduction ratio (meaning that the operation amount of the actuator is small relative to the operation amount of the electromagnetic motor). When a reduction gear with a large reduction ratio is employed, it can be generally considered that the value of the forward / reverse efficiency product described above becomes small. From that point of view, the system according to the aspect of this section can be considered as a kind of system that employs an actuator having a relatively small forward / reverse efficiency product. If the reduction ratio of the reduction gear is increased, the electromagnetic motor can be reduced in size.

  The mechanism of the “reduction gear” described in this section is not particularly limited. For example, it is possible to employ a reduction gear of various mechanisms such as a harmonic gear mechanism (sometimes referred to as “harmonic drive (registered trademark) mechanism”, “strain wave gearing mechanism”, etc.), a hypocycloid reduction mechanism, etc. .

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. In addition to the embodiments described below, the present invention can be claimed in various aspects including various modifications and improvements based on the knowledge of those skilled in the art, including the aspects described in the above [Aspect of the Invention] section. Can be implemented.

<Configuration of vehicle suspension system>
FIG. 1 schematically shows a vehicle suspension system 10 according to an embodiment. The system 10 includes four suspension devices 20 provided corresponding to the front, rear, left and right four wheels 12 and a control device that controls the suspension devices 20. Since the front wheel suspension device 20 that is a steered wheel and the rear wheel suspension device 20 that is a non-steered wheel can be regarded as substantially the same configuration except for a mechanism that enables the wheel to steer, the simplification of the description is taken into consideration. The rear wheel suspension device 20 will be described as a representative.

  As shown in FIGS. 2 and 3, the suspension device 20 is an independent suspension type and is a multi-link type suspension device. The suspension device 20 includes a first upper arm 30, a second upper arm 32, a first lower arm 34, a second lower arm 36, and a toe control arm 38, each of which is a suspension arm as a wheel holding member. One end of each of the five arms 30, 32, 34, 36, and 38 is rotatably connected to the vehicle body, and the other end is rotatable to an axle carrier 40 that rotatably holds the wheel 12. It is connected. With these five arms 30, 32, 34, 36, and 38, the axle carrier 40 can move up and down so as to draw a substantially constant locus with respect to the vehicle body.

  The suspension device 20 includes a coil spring 50 as a suspension spring and a hydraulic shock absorber (hereinafter sometimes abbreviated as “absorber”) 52, which are each a component part of the spring top. Between the mount part 54 provided in the tire housing and the second lower arm 36 which is one component part of the unsprung part, they are arranged in parallel to each other.

  As shown in FIG. 4, the absorber 52 is connected to the second lower arm 36 and accommodates a generally cylindrical housing 60 containing hydraulic fluid, and is fitted into the housing 60 in a liquid-tight and slidable manner. And a piston rod 64 having a lower end connected to the piston 62 and an upper end extending from above the housing 60. The piston rod 64 passes through a lid portion 66 provided on the upper portion of the housing 60, and is in sliding contact with the lid portion 66 via a seal 68. Further, the interior of the housing 60 is partitioned by the piston 62 into an upper chamber 70 that exists above it and a lower chamber 72 that exists below it.

  Further, the absorber 52 includes an electromagnetic motor 74, and the electromagnetic motor 74 is fixedly accommodated in a motor case 76. The motor case 76 is connected to the mount portion 54 via a buffer rubber at the outer peripheral portion thereof, and the piston rod 64 is fixedly connected to the motor case 76 at the upper end portion thereof. With such a structure, the piston rod 64 is fixed to the mount portion 54. The piston rod 64 has a hollow shape and has a through hole 77 that penetrates the piston rod 64. As will be described in detail later, an adjustment rod 78 is inserted into the through hole 77 so as to be movable in the axial direction, and the adjustment rod 78 is connected to the electromagnetic motor 74 at the upper end portion thereof. More specifically, an operation conversion mechanism 79 that converts rotation of the electromagnetic motor 74 into movement in the axial direction is provided below the electromagnetic motor 74, and the upper end portion of the adjustment rod 78 is connected to the operation conversion mechanism 79. Has been. With such a structure, when the electromagnetic motor 74 is operated, the adjustment rod 78 is moved in the axial direction.

  As shown in FIG. 5, the housing 60 includes an outer cylinder 80 and an inner cylinder 82, and a buffer chamber 84 is formed between them. The piston 62 is fitted in the inner cylinder 82 so as to be liquid-tight and slidable. The piston 62 is provided with a plurality of connection passages 86 (two are shown in FIG. 5) that penetrate in the axial direction and connect the upper chamber 70 and the lower chamber 72. A circular valve plate 88 made of an elastic material is disposed on the lower surface of the piston 62 so as to be in contact with the lower surface, and the valve plate 88 blocks the opening on the lower chamber 72 side of the connection passage 86. It has a structure. The piston 62 is provided with a plurality of connection passages 90 (two shown in FIG. 5) at positions different from the connection passage 86 in the radial direction of the piston 62. A circular valve plate 92 made of an elastic material is disposed on the upper surface of the piston 62 so as to be in contact with the upper surface, and the valve plate 92 blocks the opening on the upper chamber 70 side of the connection passage 90. It has a structure. This connection passage 90 is provided on the outer peripheral side of the connection passage 86 and at a position away from the valve plate 88, and is always in communication with the lower chamber 72. Further, since the opening 94 is provided in the valve plate 92, the opening on the upper chamber 70 side of the connection passage 86 is not blocked, and the connection passage 86 is always in communication with the upper chamber 70. ing. Further, the lower chamber 72 and the buffer chamber 84 are communicated with each other, and a base valve body 96 provided with a connection passage and a valve plate similar to the piston 62 is provided between the lower chamber 72 and the buffer chamber 84. It has been.

  The through-hole 77 inside the piston rod 64 has a large-diameter portion 98 and a small-diameter portion 100 extending below the large-diameter portion 98, and the large-diameter portion 98 and the small-diameter portion 100 of the through-hole 77 A step surface 102 is formed at the boundary portion. A connection passage 104 that connects the upper chamber 70 and the passage 77 is provided above the step surface 102. The upper chamber 70 and the lower chamber 72 are communicated with each other by the connection passage 104 and the through hole 77. The adjusting rod 78 is inserted into the large diameter portion 98 of the through hole 77 from the upper end portion of the piston rod 64. A lower end portion of the adjustment rod 78 is a conical portion 106 formed in a conical shape, and a tip end portion of the conical portion 106 can enter the small diameter portion 100 of the passage 77. A clearance 108 is formed between the 77 step surfaces 102. Incidentally, the outer diameter of the adjustment rod 78 is made larger than the inner diameter of the small diameter portion 100 of the passage 77. A seal 109 is provided between the inner peripheral surface of the through-hole 77 and the outer peripheral surface of the adjustment rod 78 above the connection passage 104 in the through-hole 77, and hydraulic fluid is disposed above the through-hole 77. It is prevented from leaking.

  With the structure as described above, for example, when the spring top and the spring bottom are separated and the piston 62 is moved upward, that is, when the absorber 52 is extended, a part of the working fluid in the upper chamber 70 is obtained. Flows through the connection passage 86 and the clearance 108 of the through hole 77 to the lower chamber 72, and part of the hydraulic fluid in the buffer chamber 84 flows into the lower chamber 72 through the connection passage of the base valve body 96. At that time, the hydraulic fluid deflects the valve plate 88 and flows into the lower chamber 72, the hydraulic fluid deflects the valve plate of the base valve body 96 and flows into the lower chamber 72, and the hydraulic fluid flows. By passing through the clearance 108 in the through hole 77, a resistance force is applied to the upward movement of the piston 62, and a damping force for the movement is generated by the resistance force. Conversely, when the upper and lower parts of the spring approach each other and the piston 62 is moved downward in the housing 60, that is, when the absorber 52 is contracted, a part of the hydraulic fluid in the lower chamber 72 is obtained. Flows through the connection passage 90 and the clearance 108 of the through hole 77 from the lower chamber 72 to the upper chamber 70, and flows out to the buffer chamber 84 through the connection passage of the base valve body 96. At that time, the hydraulic fluid deflects the valve plate 92 and flows into the upper chamber 70, the hydraulic fluid deflects the valve plate of the base valve body 96 and flows into the upper chamber 70, and the hydraulic fluid flows. By passing through the clearance 108 in the through hole 77, a resistance force is applied to the downward movement of the piston 62, and a damping force for the movement is generated by the resistance force. That is, the absorber 52 is configured to generate a damping force with respect to the approaching / separating operation in the vertical direction between the spring upper portion and the spring lower portion.

Further, as described above, the adjustment rod 78 can be moved in the axial direction by the operation of the electromagnetic motor 74, and the size (cross-sectional area) of the clearance 108 of the through hole 77 can be changed. Yes. When the hydraulic fluid passes through the clearance 108, as described above, a resistance force to the upward and downward movement of the piston 62 is applied. The magnitude of the resistance force depends on the size of the clearance 108. Change. Therefore, the absorber 52 moves the adjusting rod 78 in the axial direction by the operation of the electromagnetic motor 74 and changes the clearance 108 thereof, thereby reducing the damping characteristic with respect to the approach / separation operation between the spring upper part and the spring lower part, in other words, The so-called attenuation coefficient can be changed. More specifically, the electromagnetic motor 74 is controlled so that the rotation angle thereof is a rotation angle corresponding to the attenuation coefficient that the absorber 52 should have, and the attenuation coefficient of the absorber 52 is changed. Incidentally, the electromagnetic motor 74 is a stepping motor, and the rotation angle position at which the electromagnetic motor 74 is stopped is a preset position. Specifically, when changing the rotational angle position of the electromagnetic motor 74, the electromagnetic motor 74 is driven to rotate based on a command for rotating the electromagnetic motor 74 to a predetermined operating position. That is, the damping coefficient of the absorber 52, the first damping coefficient C _1, and two values of the first damping coefficient C ₁ is greater than the second damping coefficient C ₂ is set, the absorber 52, the first damping coefficient C ₁ And the second attenuation coefficient C ₂ is a structure capable of changing the attenuation coefficient. That is, the absorber 52 is configured as described above, and thus includes an attenuation coefficient changing mechanism including the electromagnetic motor 74, the through hole 77, the adjustment rod 78, the connection passage 104, and the like. The system 10 is provided with an attenuation coefficient change switch 110 for changing the attenuation coefficient of the absorber 52 based on the driver's intention, and a desired attenuation coefficient is obtained by operating the attenuation coefficient change switch 110 of the driver. Selectively changed.

  An annular lower retainer 111 is provided on the outer periphery of the housing 60, and an annular upper retainer 114 is attached to the lower surface side of the mount portion 54 via a vibration isolating rubber 112. The coil spring 50 is supported by the lower retainer 111 and the upper retainer 114 while being sandwiched between them. An annular member 116 is fixedly provided on the outer peripheral portion of the portion accommodated in the upper chamber 70 of the piston rod 64, and an annular buffer rubber 118 is attached to the upper surface of the annular member 116. Yes. A cylindrical cushion rubber 119 is attached to the lower surface of the motor case 76. When the vehicle body and the wheel are relatively moved in a direction away from each other (hereinafter sometimes referred to as “rebound direction”), the annular member 116 comes into contact with the lower surface of the lid portion 66 of the housing 60 via the buffer rubber 118. On the contrary, when the vehicle body and the wheel are relatively moved in a direction in which the vehicle body and the wheel approach each other (hereinafter sometimes referred to as a “bound direction”), the upper surface of the lid 66 is below the lower surface of the motor case 76 via the buffer rubber 119. It comes to contact with. That is, the absorber 52 has a stopper against approach / separation between the vehicle body and the wheel, a so-called bound stopper, and a rebound stopper.

  The suspension device 20 includes an approaching / separating force generating device (hereinafter also referred to as a “generating device”) 120 that controllably generates an approaching / separating force that is a force for approaching / separating the sprung portion and the unsprung portion. Each of the generators 120 includes an L-shaped bar 122 that is generally L-shaped and an actuator 126 that rotates the bar 122. As shown in FIGS. 2 and 3, the L-shaped bar 122 is divided into a shaft portion 130 that extends substantially in the vehicle width direction and an arm portion 132 that is continuous with the shaft portion 130 and intersects with the shaft portion 130 and extends generally rearward of the vehicle. Can do. The shaft portion 130 of the L-shaped bar 122 is rotatably held at the lower portion of the vehicle body by a holder 134 fixed to the vehicle body at a location close to the arm portion 132. The actuator 126 is fixed to the vicinity of the center in the vehicle width direction of the lower part of the vehicle body by a mounting member 136 provided at one end portion thereof, and the end portion of the shaft portion 130 (the end portion on the center side in the vehicle width direction) is The actuator 126 is connected. On the other hand, the end portion of the arm portion 132 (the end portion opposite to the shaft portion 130) is connected to the second lower arm 36 via a link rod 137. More specifically, the second lower arm 36 is provided with a link rod connecting portion 138, one end of the link rod 137 is connected to the link rod connecting portion 138, and the other end is an end of the arm portion 132 of the L-shaped bar 122. Each part is connected so as to be able to swing.

  As shown in FIG. 6, the actuator 126 included in the generator 120 includes an electromagnetic motor 140 as a drive source and a speed reducer 142 that transmits the electromagnetic motor 140 at a reduced speed. The electromagnetic motor 140 and the speed reducer 142 are provided in a housing 144 that is an outer shell member of the actuator 126. The housing 144 is attached to the vehicle body by the mounting member 136 fixed to one end portion thereof. It is fixedly attached. The L-shaped bar 122 is arranged such that its shaft portion 130 extends from the other end of the housing 144. The shaft portion 130 of the L-shaped bar 122 is connected to the speed reducer 142 as will be described later in detail in a portion existing in the housing 144 thereof. Further, the shaft portion 130 is rotatably held by the housing 144 via a bush type bearing 146 at an intermediate portion in the axial direction thereof.

  The electromagnetic motor 140 includes a plurality of coils 148 fixed and arranged on one circumference along the inner surface of the peripheral wall of the housing 144, a hollow motor shaft 150 rotatably held by the housing 144, and the coil 148. And a permanent magnet 152 that is fixedly arranged on the outer periphery of the motor shaft 150. The electromagnetic motor 140 is a motor in which the coil 148 functions as a stator and the permanent magnet 152 functions as a rotor, and is a three-phase DC brushless motor. A motor rotation angle sensor 154 for detecting the rotation angle of the motor shaft 150, that is, the rotation angle of the electromagnetic motor 140 is provided in the housing 144. The motor rotation angle sensor 154 mainly includes an encoder, and is used for controlling the actuator 126, that is, controlling the generator 120.

  The reduction gear 142 includes a wave generator (wave generator) 156, a flexible gear (flex spline) 158, and a ring gear (circular spline) 160. ”And so on). The wave generator 156 includes an elliptical cam and a ball bearing fitted on the outer periphery thereof, and is fixed to one end of the motor shaft 150. The flexible gear 158 has a cup shape in which the peripheral wall portion can be elastically deformed, and a plurality of teeth (400 teeth in the speed reducer 142) are formed on the outer periphery on the opening side of the peripheral wall portion. The flexible gear 158 is connected to and supported by the shaft portion 130 of the L-shaped bar 122 described above. More specifically, the shaft portion 130 of the L-shaped bar 122 passes through the motor shaft 150, and the outer peripheral surface of the portion extending from the motor shaft 150 is relative to the bottom portion by spline fitting while penetrating the bottom portion of the flexible gear 158. It is connected non-rotatably. The ring gear 160 is generally ring-shaped and has a plurality of teeth (402 teeth in the present speed reducer 142) formed on the inner periphery, and is fixed to the housing 144. The flexible gear 158 has a peripheral wall portion fitted on the wave generator 156 and is elastically deformed into an elliptical shape, and meshes with the ring gear 160 at two locations located in the major axis direction of the ellipse and does not mesh at other locations. It is said that.

  With such a structure, when the wave generator 156 rotates once (360 degrees), that is, when the motor shaft 150 of the electromagnetic motor 140 rotates once, the flexible gear 158 and the ring gear 160 are relatively rotated by two teeth. . That is, the reduction ratio of the reduction gear 142 is 1/200. The reduction ratio of 1/200 is a relatively large reduction ratio (meaning that the rotation speed of the actuator 26 is relatively small with respect to the rotation speed of the electromagnetic motor 140), and depends on the magnitude of this reduction ratio. In this actuator 126, the electromagnetic motor 140 is downsized. Further, depending on the reduction ratio, it is difficult to be operated by an external input or the like.

  With the above configuration, when the electromagnetic motor 140 is driven, the L-shaped bar 122 is rotated by the motor force generated by the electromagnetic motor 140, and the shaft portion 130 of the L-shaped bar 122 is twisted. It will be. The torsional reaction force generated by the torsion is transmitted to the second lower arm 36 via the arm part 132, the link rod 137, and the link rod connecting part 138, and the front end part of the second lower arm 36 is pushed down or raised with respect to the vehicle body. Force, in other words, an approaching / separating force that is a force for moving the vehicle body and the wheel in the vertical direction. That is, the actuator force that is the force generated by the actuator 126 acts as an approaching / separating force via the L-shaped bar 122 that functions as an elastic body.

  As described above, the absorber 52 can change the magnitude of the damping force generated by itself. More specifically, it is possible to change a damping coefficient that is a reference for the magnitude of the damping force to be generated, that is, a value indicating its own damping force generation capability. On the other hand, the generator 120 generates an approaching / separating force that is a force for moving the upper and lower springs in the vertical direction to approach / separate, and the magnitude of the approaching / separating force can be changed. More specifically, the actuator 126 deforms the L-shaped bar 122 as an elastic body by the actuator force that depends on the motor force, that is, while twisting the shaft portion 130 of the L-shaped bar 122, Through the character-shaped bar 122, the upper and lower spring parts are caused to act as approaching and separating forces. The deformation amount of the L-shaped bar 122, that is, the torsional deformation amount of the shaft portion 130 corresponds to the operation amount of the actuator 126, and also corresponds to the actuator force. Since the approaching / separating force corresponds to an elastic force due to the deformation of the L-shaped bar 122, it corresponds to the operation amount of the actuator 126 and corresponds to the actuator force. Therefore, the approaching / separating force can be changed by changing either the operation amount of the actuator 126 or the actuator force. In the suspension system 10, the approaching / separating force is controlled by executing a control in which the operation amount of the actuator 126 is directly controlled. Incidentally, since the operation amount of the actuator 126 corresponds to the motor rotation angle of the electromagnetic motor 140, in actual control, the motor rotation angle is directly controlled.

  The configuration of the suspension device 20 can be conceptually illustrated as shown in FIG. As can be seen from the drawing, the coil spring 50, the absorber 52, and the generator 120 are disposed between a part of the vehicle body as the spring upper portion including the mount portion 54 and the spring lower portion including the second lower arm 36 and the like. Are arranged in parallel with each other. Further, the L-shaped bar 122 and the actuator 126 as elastic bodies constituting the generator 120 are arranged in series between the spring top and the spring bottom. In other words, the L-shaped bar 122 is disposed in parallel with the coil spring 50 and the absorber 52, and an actuator 126 that connects them is disposed between the L-shaped bar 122 and a part 54 of the vehicle body. It is.

  In this system, as shown in FIG. 1, a generator electronic control unit (generator ECU) 170 that executes control for four generators 120 and an absorber electronic control unit that executes control for four absorbers 52 ( Absorber ECU) 172 is provided. A control device of the suspension system 10 is configured including these two ECUs 170 and 172.

  The generating device ECU 170 is a control device that controls the operation of each actuator 126 included in each generating device 120, and includes four inverters 174 as a drive circuit corresponding to the electromagnetic motor 140 included in each actuator 126, CPU, ROM, and RAM. And a generator controller 176 mainly composed of a computer equipped with the above. On the other hand, the absorber ECU 172 is a control device that controls the operation of the electromagnetic motor 74 provided in the absorber 52. The absorber mainly includes a computer having four motor drive circuits 178 as a drive circuit and a CPU, ROM, RAM, and the like. And a controller 180 (see FIG. 13). Each of inverter 174 and each of motor drive circuits 178 are connected to battery 184 via converter 182, and each of inverters 174 is connected to electromagnetic motor 140 of corresponding generator 120, and motor drive circuit 178 Each is connected to an electromagnetic motor 74 of the corresponding absorber 52.

  Regarding the electromagnetic motor 140 included in the actuator 126 of the generator 120, the electromagnetic motor 140 is driven at a constant voltage, and the amount of power supplied to the electromagnetic motor 140 is changed by changing the amount of supplied current. The supply current amount is changed by the inverter 174 changing the ratio (duty ratio) between the pulse on time and the pulse off time by PWM (Pulse Width Modulation).

  The generator controller 176 includes the motor rotation angle sensor 154, a steering sensor 190 for detecting the steering wheel operating angle, which is the operating amount of the steering operating member as the steering amount, and the lateral force actually generated in the vehicle body. A lateral acceleration sensor 192 that detects an actual lateral acceleration that is an acceleration, a longitudinal acceleration sensor 194 that detects a longitudinal acceleration generated in the vehicle body, a spring acceleration that is provided on a mount portion 54 of the vehicle body and detects a spring vertical acceleration An unsprung longitudinal acceleration sensor 198 is connected to the sensor 196 and the second lower arm 36 to detect unsprung longitudinal acceleration. The generator controller 176 is further connected to a brake electronic control unit (hereinafter also referred to as “brake ECU”) 200 that is a control device of the brake system. The brake ECU 200 is connected to a wheel speed sensor 202 that is provided for each of the four wheels and detects the rotational speed of each of the four wheels. Has a function of estimating the traveling speed of the vehicle (hereinafter sometimes referred to as “vehicle speed”). The generator controller 176 acquires the vehicle speed from the brake ECU 200 as necessary. Further, the generator controller 176 is connected to each inverter 174 and controls them to control the electromagnetic motor 140 of each generator 120. Note that the ROM included in the computer of the generator controller 176 stores a program related to control of each generator 120 described later, various data, and the like.

  On the other hand, the attenuation controller change switch 110 is connected to the absorber controller 180. Furthermore, the absorber controller 180 is also connected to each motor drive circuit 178, and controls each absorber 52 by controlling them. Note that the ROM included in the computer of the absorber controller 180 stores a program related to the control of each absorber 52, various data, and the like. Incidentally, the generator controller 176 and the absorber controller 180 are connected to each other so as to be able to communicate with each other, and information, instructions, etc. relating to the control of the suspension system are communicated as necessary.

<Normal and reverse efficiency of the actuator of the generator>
Here, the efficiency of the actuator 126 included in the generator 120 (hereinafter sometimes referred to as “actuator efficiency”) will be considered. There are two types of actuator efficiency: normal efficiency and reverse efficiency. Actuator reverse efficiency (hereinafter sometimes referred to simply as “reverse efficiency”) η _N is defined as the ratio of the minimum motor force at which the electromagnetic motor 140 cannot be rotated by some external input to the external input. The actuator positive efficiency (hereinafter, simply referred to as “positive efficiency”) η _P is the minimum motor force required to rotate the shaft portion 130 of the L-shaped bar 122 against a certain external input. Is defined as the ratio of its external input to. That is, if the actuator force (which may be considered as actuator torque) is Fa and the motor force (which may be considered as motor torque) generated by the electromagnetic motor 140 is Fm, then the positive efficiency η _P and the reverse efficiency η _N can be expressed as:
Positive efficiency η _P = Fa _P / Fm _P
Reverse efficiency η _N = Fm _N / Fa _N

The motor force-actuator force characteristics of the actuator 126 are as shown in FIG. 8, and the normal efficiency η _P and reverse efficiency η _N of the actuator 126 are respectively the slope of the normal efficiency characteristic line and the reverse efficiency characteristic shown in the figure. This is equivalent to the reciprocal of the slope of the line. As can be seen from the figure, even when the actuator Fa having the same size is generated, the motor force Fm _P of the electromagnetic motor 140 required under the normal efficiency characteristics and the motor force Fm _N required under the reverse efficiency characteristics Then, the values are relatively different (Fm _P > Fm _N ).

Here, by defining the product of the normal efficiency eta _P and the negative efficiency eta _N and negative efficiency product η _P · η _N, the negative efficiency product η _P · η _N, against the external input of a size Therefore, it can be considered as a ratio between the motor force required to operate the actuator and the motor force required since the actuator cannot be operated by the external input. The smaller the forward / reverse efficiency product η _P · η _N is, the smaller the motor force Fm _N required under the reverse efficiency characteristic is compared with the motor force Fm _P of the electromagnetic motor required under the normal efficiency characteristic. Simply put, the smaller the forward / reverse efficiency product η _P · η _N , the less likely it is to move.

This actuator 126, as can be seen from FIG. 8, a relatively small negative efficiency product η _P · η _N, in terms of the specific numerical values, negative efficiency product η _P · η _N becomes 1/3 Therefore, the actuator is relatively difficult to operate depending on the external input. This greatly reduces the force that should be generated by the electromagnetic motor 140 as compared to the case where the actuator 126 is operated against the external input when the operation position is maintained under the action of the external input, for example. Making it possible. Since the motor force can be considered to be proportional to the power supplied to the electromagnetic motor, the power consumption is greatly reduced in this actuator 126 having a small forward / reverse efficiency product η _P · η _N.

  Specifically, when the vehicle is turning, for example, in the case where the actuator 126 is controlled to suppress the roll of the vehicle body, as will be described later, at the initial turning, the actuator is against the roll moment. On the other hand, during the turning, the operation position of the actuator 126 is maintained under the action of the roll moment. That is, in this actuator 126, the power consumption of the electromagnetic motor 140 at the time of suppressing the roll of the vehicle body is suppressed. Similarly, in the case of suppressing the pitch of the vehicle body at the time of acceleration and deceleration of the vehicle, there is a situation in which the operating position of the actuator 126 is maintained under the action of the pitch moment. For this reason, the power consumption of the electromagnetic motor 140 when suppressing the pitch of the vehicle body is also suppressed.

<Control of vehicle suspension system>
i) Basic control of generator In this suspension system 10, control to attenuate the sprung vibration corresponding to each of the four wheels 12 by independently controlling the approaching / separating force generated by each generator 120. (Hereinafter sometimes referred to as “sprung vibration damping control”), control for suppressing roll of the vehicle body caused by turning of the vehicle (hereinafter also referred to as “roll suppression control”), vehicle body caused by vehicle acceleration / deceleration The control for suppressing the pitch (hereinafter, sometimes referred to as “pitch suppression control”) is executable. In the present system 10, control in which these three controls are generally performed is executed. In this control, the motor rotation angle of the electromagnetic motor 140 is controlled in each generator 120 so as to exert an appropriate approaching / separating force based on the sprung speed, the roll moment received by the vehicle body, the pitch moment, and the like. Specifically, based on the sprung speed, the roll moment received by the vehicle body, the pitch moment, etc., the target motor rotation angle as the control target value, which is the target motor rotation angle, is determined, and the actual motor rotation angle is the target motor rotation angle. The electromagnetic motor 140 is controlled so that the motor rotation angle is obtained.

In the present system 10, the target motor rotation angle as the control target value described above is the sum of the target motor rotation angle components, which are control target value components for each control of sprung vibration damping control, roll suppression control, and pitch suppression control. To be determined. The components for each control are
Sprung vibration damping target motor rotation angle component (sprung vibration damping component) θ ^* _U
Roll suppression target motor rotation angle component (roll suppression component) θ ^* _R
Pitch suppression target motor rotation angle component (pitch suppression component) θ ^* _P
It is. Hereinafter, each of sprung vibration damping control, roll suppression control, and pitch suppression control will be described in detail with a focus on a method for determining each target motor rotation angle component, and the electromagnetic motor 140 based on the target motor rotation angle will be described. The determination of the supplied power will be described in detail.

a) On-spring vibration damping control In the on-spring vibration damping control, in order to execute damping control based on the so-called skyhook damper theory, a part of the approaching / separating force is converted to the vertical movement speed of the vehicle body, so-called absolute on-spring. It is generated as a damping force with a magnitude corresponding to the speed. Specifically, the sprung vertical acceleration Gu detected by the sprung vertical acceleration sensor 196 provided on the mount portion 54 of the vehicle body is generated in order to generate a damping force having a magnitude corresponding to the sprung absolute speed as the sprung speed. Based on the above, the sprung absolute velocity Vu is calculated, and the sprung vibration damping component θ ^* _U is calculated according to the following equation.
θ ^* _U = K ₁ · C _S · Vu
Here, K ₁ is a gain for converting the damping force for the sprung vibration into the sprung vibration component θ ^* _U , and C _S is a damping coefficient based on the skyhook damper theory.

b) Roll suppression control In roll suppression control, when the vehicle is turning, the generator 120 on the inner side of the turn turns the approaching / separating force for roll suppression control in the bounce direction according to the roll moment resulting from the turn. The generator 120 on the outer ring side generates an approaching / separating force for the roll suppression control in the rebound direction as a roll suppression force. Specifically, first, as the lateral acceleration that indicates the roll moment received by the vehicle body, the estimated lateral acceleration Gyc estimated based on the steering angle δ of the steering wheel and the vehicle traveling speed v, and the actually measured actual lateral acceleration Gyr. Based on the above, the control lateral acceleration Gy ^* , which is the lateral acceleration used for the control, is determined according to the following equation.
Gy ^* = K ₂ · Gyc + K ₃ · Gyr (K ₂ , K ₃ : gain)
Then, the roll suppression component θ ^* _R is determined based on the determined control lateral acceleration Gy ^* . The generator controller 176 stores map data of the roll suppression component θ ^* _{R using} the control lateral acceleration Gy ^* as a parameter, and the map data is referred to when determining the roll suppression component θ ^* _R. . Thus, the roll restraining component θ ^* _R is determined, and the approaching / separating force for the roll restraining control is generated, so that the roll of the vehicle body is restrained. That is, the generation device 120 can be considered as a device as if the stabilizer device was divided into left and right, in other words, a component of the left and right independent stabilizer device.

c) Pitch suppression control In the pitch suppression control, the front wheel side generator 120 approaches the pitch of the nose dive generated during braking of the vehicle body according to the pitch moment that causes the nose dive. The separating force is generated in the rebound direction, and the generator 120 on the rear wheel side generates an approaching and separating force for pitch suppression control in the bound direction as a pitch suppression force. As a result, nose diving is suppressed. Further, with respect to the squat of the vehicle body generated during the acceleration of the vehicle body, the rear wheel-side generator 120 generates the approaching / separating force for pitch suppression control in the rebound direction according to the pitch moment that generates the squat. The generator 120 generates an approaching / separating force for pitch suppression control in the bounce direction as a pitch suppression force. In the pitch suppression control, nose dives and squats are suppressed by such approach and separation force. Specifically, the actual actual longitudinal acceleration Gzg is employed as the longitudinal acceleration that indicates the pitch moment received by the vehicle body, and the pitch suppression component θ ^* _P is determined according to the following equation based on the actual longitudinal acceleration Gzg. .
θ ^* _P = K ₄ · Gzg (K ₄ : gain)

d) Determination of target supply current As described above, when the sprung vibration damping component θ ^* _U , the roll suppression component θ ^* _R , and the pitch suppression component θ ^* _P are determined, the target motor rotation angle θ ^* Determined according to the formula.
θ ^* = θ ^* _U + θ ^* _R + θ ^* _P
Then, the electromagnetic motor 140 is controlled so that the actual motor rotation angle θ, which is the actual motor rotation angle, becomes the target motor rotation angle θ ^* . In the control of the electromagnetic motor 140, the electric power supplied to the electromagnetic motor 140 is determined based on a motor rotation angle deviation Δθ (= θ ^* −θ) that is a deviation of the actual motor rotation angle θ from the target motor rotation angle θ ^* . Is done. Specifically, it is determined according to a feedback control method based on the motor rotation angle deviation Δθ. Specifically, first, the motor rotation angle deviation Δθ is recognized based on the detection value of the motor rotation angle sensor 154 included in the electromagnetic motor 140, and then the target supply current i ^* according to the following equation using it as a parameter ^. Is determined.
i ^* = K _P · Δθ + K _I · Int (Δθ)
This equation follows the PI control law. The first term and the second term mean the proportional term and the integral term, respectively, and K _P and K _I mean the proportional gain and the integral gain, respectively. Int (Δθ) corresponds to an integral value of the motor rotation angle deviation Δθ. The motor rotation angle deviation Δθ represents the direction in which the actual motor rotation angle θ should approach the target motor rotation angle θ ^* , that is, the operation direction of the electromagnetic motor 140, and its absolute value should be operated. It represents the quantity.

The formula for determining the target supply current i ^* is composed of two terms, and each of the two terms can be considered as a component of the target supply power. The component of the first term is a component i _h corresponding to the motor rotation angle deviation Δθ (hereinafter sometimes referred to as “proportional term current component”), and the component of the second term is based on the integration of the deviation Δθ. Component (hereinafter sometimes referred to as “integral term current component”) i _S. The actuator 126 operates while receiving an external input such as an elastic reaction force of the L-shaped bar 122. According to the theory of PI control, the integral term current component i _S is rotated by the electromagnetic motor 140 depending on the external input. It can be considered as a current component for preventing this, that is, a component relating to the motor force for maintaining the operating position of the actuator 126 under the action of an external input. The proportional term current component i _h is a current component for appropriately operating the actuator 126 under the action of an external input, that is, a motor force for operating the actuator 126 against the external input, or It can be considered as a component related to the motor force for appropriately operating the actuator 126 using an external input.

Here, given the previous actuator efficiency, generally speaking, the integral term current component i _S, since may be a current component for maintaining the motor rotation angle theta, the size of the motor according to the negative efficiency eta _N Any current component that generates force can be used. Therefore, the integral gain K _I that is the gain of the second term in the above equation for determining the target supply current i ^* is set so that the integral term component i _S has a value that is in line with the inverse efficiency characteristic. For example, when considering the roll suppression when the vehicle performs a typical one-turn operation, as shown in FIG. 9, the roll suppression force that the generator 120 should generate, that is, the approach and separation for roll suppression control. The force changes, and the target motor rotation angle θ ^* of the electromagnetic motor 140 changes. In this example, the integral term current component i is maintained so that the motor rotation angle can maintain the target motor rotation angle θ ^* through the actual motor rotation initial stage [a], the intermediate period [b], and the latter period [c]. _S is determined according to the reverse efficiency η _N.

On the other hand, the proportional term current component i _h is a component for eliminating the deviation of the actual motor rotation angle θ with respect to the target motor rotation angle θ ^* under the action of an external input, and is the gain of the first term in the above equation. The proportional gain K _P is set to such a value that appropriate increase / decrease correction of the proportional term current component i _h according to the motor rotation angle deviation Δθ is performed. In particular, at the beginning of turning [a], the actuator 126 must be operated against an external input. Therefore, a current that is large enough to generate a motor force that exceeds the motor force according to the positive efficiency characteristic is generated by the electromagnetic motor 140. Need to be supplied. In view of this, the proportional gain K _P is set to a value that can generate a motor force according to the positive efficiency characteristic in a state where the motor rotation angle deviation Δθ does not become so large.

Although the roll suppression control has been described as an example, by determining the target supply current i ^* according to the above formula in which the proportional gain K _P and the integral gain K _I are appropriately set, in the pitch suppression control or the control in which they are combined. Similarly, the positive efficiency η _P and the reverse efficiency η _N of the actuator 126 are taken into consideration. Therefore, by determining the target supply current i ^* in consideration of the positive efficiency η _P and the reverse efficiency η _N of the actuator 126, the state in which the motor rotation angle θ is maintained and reduced, in other words, the motor force, That is, the power consumption of the electromagnetic motor 140 is effectively reduced in a state where the actuator force and the approaching / separating force are maintained at the same magnitude and in a reduced state.

Incidentally, the target supply current i ^* also indicates the direction of generation of the motor force of the electromagnetic motor 140 by its sign, and the drive control of the electromagnetic motor 140 is based on the target supply current i ^* . The duty ratio for driving the electromagnetic motor 140 and the motor force generation direction are determined. Then, a command regarding the duty ratio and the direction in which the motor force is generated is issued to the inverter 174, and the inverter 174 controls the drive of the electromagnetic motor 140 based on the command.

In the present embodiment, the target supply current i ^* is determined according to the PI control law, but the target supply current i ^* can also be determined according to the PDI control law. In this case, for example, the following formula: i ^* = K _P · Δθ + K _I · Int (Δθ) + K _D · Δθ ′
Thus, the target supply current i ^* may be determined. Here, K _D is the differential gain, the third term means a differential term component.

ii) Unsprung displacement increase control By executing the above-described sprung vibration damping control, roll restraining control, and pitch restraining control, it is possible to restrain the posture change of the vehicle body and to attenuate the vibration of the sprung portion. However, by dampening the sprung vibration, there is a possibility that the grounding property of the wheel may be lowered depending on the direction in which each of the sprung portion and the unsprung portion operates. More specifically, if the vertical movement of the unsprung portion is hindered by the approaching / separating force generated to attenuate the sprung vibration, the grounding property of the wheel may be lowered.

  For example, when a vehicle equipped with the system 10 travels on a road as shown in FIG. 10, in the state shown in FIG. The unsprung portion also moves upward, and the approaching / separating force generated to attenuate the sprung vibration is a force in a direction in which the sprung portion and the unsprung portion are brought closer to each other. For this reason, when the unsprung part moves upward, the unsprung part is pulled upward by the approaching / separating force. That is, the vertical movement of the lower part of the spring is promoted by the approaching / separating force for the sprung vibration damping control, and the followability of the wheel to the road surface is ensured, so that there is little possibility that the grounding property of the wheel is lowered.

  However, in the state shown in FIG. 10B, the upper part of the spring moves upward, the lower part of the spring moves downward, and the approaching / separating force for attenuating the sprung vibration is different from that of the upper part of the spring. It becomes the force in the direction to bring the unsprung portion closer. For this reason, when the unsprung portion moves downward, the unsprung portion is pulled upward by the approaching / separating force. In other words, the vertical movement of the lower part of the spring is hindered by the approaching / separating force for the sprung vibration damping control, and the followability of the wheel to the road surface is deteriorated, so that the grounding property of the wheel is lowered. In the figure, the solid line arrow indicates the direction of movement of the upper part of the spring, the dotted line arrow indicates the direction of movement of the lower part of the spring, and the alternate long and short dash line indicates the direction of generation of the approaching / separating force for damping the sprung vibration. Show.

  In the state shown in FIG. 10C, both the sprung portion and the unsprung portion move downward, and the approaching / separating force for damping the sprung vibration is in the direction of separating the sprung portion and the unsprung portion. It becomes power. For this reason, when the unsprung part moves downward, the unsprung part is pressed downward by the approaching / separating force. That is, the movement of the unsprung portion is promoted by the approaching / separating force, and the followability to the road surface of the wheel is ensured, so that there is little possibility that the grounding property of the wheel is lowered. In the state shown in FIG. 10 (d), the sprung portion moves downward, the unsprung portion moves upward, and the approaching / separating force for damping the sprung vibration is the same as that of the sprung portion. The force is in the direction of separating the unsprung part. For this reason, when the unsprung part moves upward, the unsprung part is pressed downward by the approaching / separating force, so that the operation of the unsprung part is hindered and the grounding property of the wheel is lowered.

  Incidentally, there is a possibility that the grounding property may be lowered when the vehicle passes through the unevenness of the road surface. Specifically, as shown in FIG. 10 (e), when the vehicle passes through the recess, the upper part of the spring moves upward and the lower part of the spring moves downward, The approaching / separating force for attenuating the vibration is a force in a direction in which the sprung portion and the unsprung portion are brought closer to each other. For this reason, the movement of the unsprung portion is hindered by the approaching / separating force, and the grounding performance of the wheel is lowered. Further, as shown in FIG. 10 (f), when the vehicle passes through the convex portion, the upper portion of the spring moves downward and the lower portion of the spring moves upward to attenuate the sprung vibration. The approaching / separating force for doing this is a force in the direction of separating the spring top and the spring bottom. For this reason, the movement of the unsprung portion is hindered by the approaching / separating force, and the grounding performance of the wheel is lowered.

  As described above, when the direction of the motion of the sprung portion and the direction of the motion of the unsprung portion are different from each other, there is a possibility that the grounding property of the wheel may be lowered by the approaching / separating force for damping the sprung vibration. For this reason, in the present system 10, when the sprung portion and the unsprung portion are operated in different directions when the sprung vibration damping control is executed, the vertical direction of the unsprung portion is improved in order to improve the followability of the wheel to the road surface. Unsprung displacement increase control is executed to increase the displacement of.

More specifically, in the unsprung displacement increase control, a part of the approaching / separating force is generated as a force that increases the displacement of the unsprung portion in accordance with the unsprung displacement amount that is the amount of displacement of the unsprung portion in the vertical direction. ing. Specifically, in order to promote the displacement of the unsprung portion according to the unsprung displacement amount, the unsprung displacement amount Xs is based on the unsprung longitudinal acceleration Gs detected by the unsprung longitudinal acceleration sensor 198 provided in the unsprung portion. The unsprung displacement increase target motor rotation angle component (unsprung displacement increase component) θ ^* _SH, which is a motor rotation angle component for executing unsprung displacement increase control, is calculated according to the following equation.
θ ^* _SH = K ₅ · (k _S + k _B ) · Xs
Here, k _S is a spring constant of the coil spring 50, and k _B is a spring constant of the L-shaped bar 122. K ₅ is a gain for converting a force that increases unsprung displacement into an unsprung displacement increasing component θ ^* _SH .

When the unsprung displacement increasing component θ ^* _SH is determined as described above, and the sprung vibration damping component θ ^* _U , the roll suppressing component θ ^* _R , and the pitch suppressing component θ ^* _P are respectively determined, the target motor rotation The angle θ ^* is determined according to the following equation:
θ ^* = θ ^* _U + θ ^* _R + θ ^* _P + θ ^* _SH
Based on the determined target motor rotation angle θ ^* , the electromagnetic motor 140 is controlled as described above.

iii) Absorber control In the present system 10, as described above, the generator 120 has a relatively high frequency because the actuator 126 has a relatively small forward / reverse efficiency product η _P · η _N. It is difficult to cope with vibrations in the area. Therefore, the absorber 52 provided in the present system 10 is an absorber suitable for vibration attenuation in the high frequency range, and the action of the absorber 52 suppresses transmission of vibration in a relatively high frequency range to the vehicle body. Become. That is, in the present system 10, vibrations in a relatively low frequency range where the operation of the actuator 126 can sufficiently follow, that is, a low frequency range including the sprung resonance frequency, are dealt with by the generator 120, and the unsprung resonance frequency is set. The absorber 52 copes with the vibration in the high frequency range including it. For this reason, the absorber 52 employs an attenuation coefficient set as low as possible in order to ensure the above functions.

However, the value of the damping system number of the absorber 52 not only affects the transmission of vibration from the unsprung portion to the unsprung portion but also affects the grounding property of the wheel. Specifically, as shown in FIG. 11, the ground load fluctuation rate with respect to vibration of the unsprung resonance frequency is higher as the damping coefficient is smaller. In particular, when the damping coefficient becomes small to some extent, as can be seen from the figure, the contact load fluctuation rate is remarkably high. The ground load variation rate and the wheel grounding property are in a relative relationship. The higher the ground load variation rate, the lower the wheel grounding property. Therefore, the smaller the damping coefficient, the smaller the grounding property against vibration at the unsprung resonance frequency. It is low. That is, when the damping coefficient is reduced to some extent, the grounding property against vibration at the unsprung resonance frequency is significantly reduced. Accordingly, the present system 10, the first damping coefficient C ₁ of the absorber 52 is set in consideration of the balance between the ground of the wheel relatively transmission of high-frequency vibration range and for the vibration. Specifically, the first damping coefficient C ₁ of the absorber 52 is 1500 N · sec / m (a value that is assumed to be directly applied to the wheel with respect to the operation of the wheel). It is set to less than half of 3000 to 5000 N · sec / m which is a value set for a shock absorber in a suspension system that is not used, that is, a conventional shock absorber.

However, depending on the driver's intention, the traveling state of the vehicle, and the like, there may be a case where the vehicle characteristics that emphasize the maneuverability are desirable even if the ride comfort of the vehicle is sacrificed to some extent. For this reason, the absorber 52 of the present system 10 is also set with a second damping coefficient C ₂ that is larger than the first damping coefficient C ₁ set relatively low, and the driver's damping coefficient change switch 110 is set. By this operation, the attenuation coefficient is changed to either the first attenuation coefficient C ₁ or the second attenuation coefficient C ₂ . More specifically, the operation of the electromagnetic motor 74 is controlled so that the rotational angle position of the electromagnetic motor 74 of the absorber 52 becomes a predetermined position in accordance with a command based on the operation of the attenuation coefficient change switch 110, and the attenuation coefficient is One of the first attenuation coefficient C ₁ and the second attenuation coefficient C ₂ is changed.

iv) Unsprung acceleration control The absorber 52 of the present system 10 is set with a second damping coefficient C ₂ having a value larger than the first damping coefficient C ₁ in order to make the vehicle characteristics prioritize maneuverability. Yes. If the damping coefficient of the absorber 52 is a second damping coefficient C _2, that is, when the damping effect is high, the vibration from the unsprung portion to the sprung portion is easily transferred. Even when the damping coefficient is set to the second damping coefficient C ₂ in order to make the vehicle characteristics emphasizing maneuverability, it is desirable to suppress the transmission of vibration from the unsprung part to the unsprung part to some extent. . In particular, when the ground contact property of the wheel is ensured by the unsprung displacement increase control, the vibration input from the unsprung portion tends to be transmitted to the unsprung portion. Is desired. Therefore, in the present system 10, suppression with attenuation coefficient of the absorber 52 is a second damping coefficient C _2, when the unsprung displacement increase control is executed, the transmission of vibration from the unsprung portion to the sprung portion Therefore, the damping effect of the unsprung portion is reduced. That is, when executing the unsprung displacement increasing control, if the damping coefficient of the absorber 52 is larger than the first damping coefficient C ₁ as the set threshold damping coefficient, the unsprung speed increasing control for increasing the vertical movement of the unsprung part. Is executed.

Specifically, in the unsprung acceleration control, a part of the approaching / separating force is generated as a force that accelerates the operation of the unsprung portion of the magnitude corresponding to the unsprung velocity, which is the up-down direction operating speed of the unsprung portion. ing. That is, it is generated as a driving force for the operation of the unsprung portion. Specifically, the unsprung absolute velocity Vs is calculated based on the unsprung longitudinal acceleration Gs detected by the unsprung longitudinal acceleration sensor 198 provided in the unsprung portion, and the unsprung acceleration control is executed according to the following equation. The unsprung acceleration target motor rotation angle component (unsprung acceleration component) θ ^* _SS is calculated.
θ ^* _SS = K ₆ · (C _2- C ₁ ) · Vs
Here, K ₆ is a gain for converting the force for accelerating the operation of the unsprung portion into the unsprung acceleration component θ ^* _SS .

When the unsprung acceleration component θ ^* _SH is determined as described above, the target motor rotation angle θ ^* is determined according to the following equation together with the components θ ^* _U , θ ^* _R , θ ^* _P , and θ ^* _SH. ,
θ ^* = θ ^* _U + θ ^* _R + θ ^* _P + θ ^* _SH + θ ^* _SS
Based on the determined target motor rotation angle θ ^* , the electromagnetic motor 140 is controlled as described above.

<Control program>
In the present system 10, the approaching / separating force generated by the generator 120 is controlled by the generator controller 176 executing a generator control program shown in the flowchart of FIG. This program is repeatedly executed with a short time interval (for example, several msec) while the ignition switch is in the ON state. The control flow will be briefly described below with reference to the flowchart shown in the figure. Note that the generator control program is executed for each actuator 126 of the four generators 120. In the following description, control processing for one actuator 126 is considered in consideration of simplification of the description. explain.

In the processing according to this program, first, in step 1 (hereinafter simply referred to as “S1”, the same applies to other steps), based on the sprung vertical acceleration Gu detected by the sprung vertical acceleration sensor 196, The sprung absolute speed Vu is calculated, and the sprung vibration damping component θ ^* _U for the sprung vibration damping control is determined based on the calculated sprung absolute speed Vu in S2. Next, in S3, a control lateral acceleration Gy ^* is calculated based on the actual lateral acceleration Gyr detected by the lateral acceleration sensor 192 and the estimated lateral acceleration Gyc. In S4, based on the control lateral acceleration Gy ^*. The roll suppression component θ ^* _R for roll suppression control is determined. Subsequently, in S5, the longitudinal acceleration Gzg is detected by the longitudinal acceleration sensor 194, and in S6, a pitch suppression component θ ^* _P for pitch suppression control is determined based on the detected longitudinal acceleration Gzg.

Next, in S7, the unsprung absolute velocity Vs is calculated based on the unsprung longitudinal acceleration Gs detected by the unsprung longitudinal acceleration sensor 198. In S8, the direction of the unsprung portion and the direction of the unsprung portion are calculated. Are different from each other. Specifically, it is determined whether or not the sign of the sprung absolute speed Vu and the sign of the unsprung absolute speed Vs are different from each other. If it is determined that the signs of the absolute velocities Vu and Vs are different from each other, an unsprung displacement amount Xs is calculated based on the unsprung absolute velocity Vs in S9, and the calculated unsprung displacement amount is calculated in S10. Based on Xs, an unsprung displacement increasing component θ ^* _SH for unsprung displacement increasing control is determined. Subsequently, in S11, whether or not the damping coefficient of the absorber 52 is a second damping coefficient C ₂ is determined. Damping coefficient of the absorber 52 when it is determined that there is a second damping coefficient C _2, at S12, the unsprung acceleration component theta ^* _SS for the unsprung acceleration control is determined, in S13, The target motor is obtained by summing the sprung vibration damping component θ ^* _U , the roll suppressing component θ ^* _R , the pitch suppressing component θ ^* _P , the unsprung displacement increasing component θ ^* _SH, and the unsprung increasing component θ ^* _SS. The rotation angle θ ^* is determined.

When it is determined in S8 that the signs of the absolute velocities Vu and Vs are the same, in S14, the sprung vibration damping component θ ^* _U , the roll suppression component θ ^* _R, and the pitch suppression component θ ^* _P target motor rotational angle theta ^* is determined, the damping coefficient of the absorber 52 in S11 is a case where it is determined that there is a first damping coefficient C _1, in S15, the sprung-vibration damping component by but summed The target motor rotation angle θ ^* is determined by summing θ ^* _U , roll suppression component θ ^* _R , pitch suppression component θ ^* _P, and unsprung displacement increase component θ ^* _SH . When the target motor rotation angle θ ^* is determined, the actual motor rotation angle θ is acquired based on the motor rotation angle sensor 154 in S16, and in S17, the deviation of the actual motor rotation angle θ from the target motor rotation angle θ ^* is obtained. A certain motor rotation angle deviation Δθ is determined. In S18, based on the target motor rotation angle θ ^* , the target supply current i ^* is determined according to the formula according to the above-described PI control law. In S19, the control signal based on the determined target supply current i ^* is transmitted to the inverter 174. After being transmitted to, one execution of this program ends.

<Functional configuration of controller>
The generator controller 176 that executes the generator control program can be considered to have a functional configuration as shown in FIG. 13 in view of its execution processing. As can be seen from the figure, the generator controller 176 uses the sprung vibration damping control unit 210 as a function unit for executing the processes of S1 and S2, that is, a function unit for executing the sprung vibration damping control. As a functional unit that executes processing, that is, a functional unit that executes roll suppression control, the roll suppression control unit 212 is used as a functional unit that executes the processes of S5 and S6, that is, as a functional unit that executes pitch suppression control. The suppression control unit 214 is a functional unit that executes the processes of S9 and S10, that is, a functional unit that executes the unsprung displacement increase control, and the unsprung displacement increase control unit 216 is a functional unit that executes the process of S12. The unsprung acceleration control unit 218 is provided as a functional unit that executes unsprung acceleration control. Further, the absorber controller 180 that controls the operation of the electromagnetic motor 74 of the attenuation coefficient changing mechanism provided in the absorber 52 can also be considered to have a functional configuration as shown in FIG. As can be seen from the figure, the absorber controller 180 includes an attenuation coefficient changing unit 220 as a functional unit that changes the attenuation coefficient of the absorber 52 based on the operation of the attenuation coefficient changing switch 110.

1 is a schematic diagram showing the overall configuration of a vehicle suspension system that is an embodiment of the claimable invention. It is a schematic diagram which shows the suspension apparatus with which the suspension system for vehicles of FIG. 1 is provided from the viewpoint from the vehicle rear. It is a schematic diagram which shows the suspension apparatus with which the suspension system for vehicles of FIG. 1 is provided from the viewpoint from the vehicle upper side. It is a schematic sectional drawing which shows the absorber with which a suspension apparatus is provided. It is an enlarged view of the schematic sectional drawing of the absorber of FIG. It is a schematic sectional drawing which shows the actuator which comprises the generator provided with a suspension apparatus. It is a figure which shows a suspension apparatus notionally. It is a graph which shows notionally the normal efficiency and reverse efficiency of an actuator of an example. 7 is a chart schematically showing changes in roll suppression force, target motor rotation angle, actual motor rotation angle, proportional term current component, integral term current component, and target supply current over time during a typical turning operation of a vehicle. . It is a figure which shows notionally the motion of the suspension apparatus at the time of vehicle travel. It is a graph which shows notionally the relationship between the ground load fluctuation rate with respect to the vibration of an unsprung resonance frequency, and a damping coefficient. It is a flowchart which shows a generator control program. It is a block diagram which shows the function of the control apparatus which manages control of a suspension system.

Explanation of symbols

  10: Vehicle suspension system 36: Second lower arm (lower spring) 50: Coil spring (suspension spring) 52: Shock absorber 54: Mount part (upper spring) 74: Electromagnetic motor (damping coefficient changing mechanism) 77: Through hole ( Damping coefficient changing mechanism) 78: Adjustment rod (damping coefficient changing mechanism) 79: Motion conversion mechanism (damping coefficient changing mechanism) 120: Approaching / separating force generator 122: L-shaped bar (elastic body) 126: Actuator 130: Shaft portion 132 : Arm part 140: Electromagnetic motor 142: Reducer 170: Generator electronic control unit (control device) 210: Sprung vibration damping control part 212: Roll suppression control part 214: Pitch suppression control part 216: Unsprung displacement increase control part 218: If Under acceleration control unit

Claims (11)

A suspension spring that elastically connects the sprung portion and the unsprung portion;
An approaching / separating force generating device that has an electromagnetic motor and generates an approaching / separating force that is a force for approaching / separating the sprung portion and the unsprung portion based on the force generated by the electromagnetic motor;
A vehicle suspension system comprising: a control device that controls an approaching / separating force generated by the approaching / separating force generating device by controlling an operation of the electromagnetic motor;
The control device is
A sprung vibration damping control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part of the approach / separation force becomes a damping force with respect to the vibration of the sprung portion having a magnitude corresponding to the sprung speed;
When the control by the sprung vibration damping control unit is executed, the approaching / separating force generated by the approaching / separating force generator is different from the approaching / separating force generating device when the direction of the operation of the sprung portion is different from the direction of the operation of the unsprung portion. A suspension system for a vehicle, comprising: an unsprung displacement increase control unit that controls the portion to have a force that increases the unsprung displacement according to the unsprung displacement amount. The vehicle suspension system includes a hydraulic shock absorber that generates a damping force that attenuates the relative vibrations of the upper and lower springs.
The control device further comprises:
During the execution of the control by the unsprung displacement increase control unit, the approaching / separating force generated by the approaching / separating force generating device partly accelerates the operation of the unsprung portion having a magnitude corresponding to the unsprung speed. The suspension system for a vehicle according to claim 1, further comprising an unsprung acceleration control unit that controls the force to be a force. The shock absorber has a damping coefficient changing mechanism that changes a damping coefficient that is a reference of damping force generated by itself.
The unsprung acceleration control unit is
Only when the damping coefficient of the shock absorber is larger than a set threshold damping coefficient, the approaching / separating force generated by the approaching / separating force generating device becomes a force that accelerates the operation of the unsprung portion. The vehicle suspension system according to claim 2, wherein the suspension system is configured to control a separation force. The unsprung acceleration control unit is
The approaching / separating force generating device such that the magnitude of the force for accelerating the operation of the unsprung portion is a magnitude obtained by multiplying the value obtained by subtracting the set threshold damping coefficient from the damping coefficient of the shock absorber and the unsprung speed. The vehicle suspension system according to claim 3, configured to control an approaching / separating force generated by the vehicle.   5. The vehicle suspension system according to claim 3, wherein the set threshold damping coefficient is set to a value that makes an appropriate damping characteristic for vibration at an unsprung resonance frequency.   The vehicle suspension system according to any one of claims 3 to 5, wherein the set threshold damping coefficient is set to 1000 N · sec / m or more and 2000 N · sec / m or less. The control device further comprises:
A roll suppression control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part thereof is a force that suppresses the roll of the vehicle body caused by turning of the vehicle;
And a pitch suppression control unit that controls the approaching / separating force generated by the approaching / separating force generating device so that at least a part thereof is a force that suppresses the pitch of the vehicle body caused by acceleration / deceleration of the vehicle. The vehicle suspension system according to any one of claims 1 to 6. The approaching / separating force generator is
An elastic body having one end connected to the unsprung portion;
The other end of the elastic body is held and fixed to the vehicle body, and the force generated by the electromagnetic motor is applied to the elastic body based on the force generated by the electromagnetic motor using the electromagnetic motor as a component of the electromagnetic motor. And an electromagnetic actuator that changes the amount of deformation of the elastic body in accordance with the amount of movement of the elastic body and that acts on the spring upper part and the spring unsprung via the elastic body. Item 8. The vehicle suspension system according to any one of Items 7. The elastic body has a shaft portion rotatably held by the actuator, and an arm portion that extends from one end portion of the shaft portion so as to intersect the shaft portion and has a tip portion connected to a wheel holding member that holds a wheel. And
9. The vehicle suspension system according to claim 8, wherein the actuator rotates the shaft portion around an axis thereof by a force generated by the actuator. The ratio of the external input to the force of the electromagnetic motor required to operate the actuator against the external input is necessary for the positive efficiency of the actuator and the actuator not to be operated by the external input. When the ratio of the electromagnetic motor force to the external input is defined, the reverse efficiency of the actuator, the product of the normal efficiency and the reverse efficiency, and the normal / reverse efficiency product, respectively,
The vehicle suspension system according to claim 8 or 9, wherein the actuator has a structure having a forward / reverse efficiency product of 1/2 or less.   The actuator has a speed reducer that decelerates the operation of the electromagnetic motor, and the operation decelerated by the speed reducer becomes its own operation, and the reduction ratio of the speed reducer is 1/100 or less. The vehicle suspension system according to any one of claims 8 to 10.

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