JP2008114722A - Vehicular suspension system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical vehicular suspension system. <P>SOLUTION: In a system wherein a suspension spring, a hydraulic absorber having a function for changing a damping coefficient and for generating damping force in relation to the relative vibration between an upper part and a lower part of the spring, and an approaching and separating force generating device for generating approaching and separating force freely to control it are arranged in parallel with each other, in the case of increasing the damping coefficient of the absorber, before changing the damping coefficient with the damping coefficient changing mechanism (t<SB>1</SB>), damping force F is compensated by using the approaching and separating force (an oblique line) generated by the approaching and separating force generating device, and thereafter (t<SB>2</SB>), the control for increasing the damping coefficient is carried out by the damping coefficient changing mechanism, reducing the approaching and separating force. With this system, an impact applied to the absorber with operation of the damping coefficient changing mechanism can be restricted, and damping ability of the absorber can be smoothly increased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle suspension system, and more particularly, to a vehicle suspension system including a hydraulic shock absorber (hereinafter, may be abbreviated as “absorber”) whose damping coefficient can be changed.

Currently, a hydraulic suspension as described in Patent Document 1 below, that is, a vehicle suspension system including an absorber capable of changing a damping coefficient is put into practical use. Further, as described in Patent Documents 2 to 4 below, a force for moving the spring upper part and the spring lower part closer to and away from each other based on the operation of the electromagnetic actuator (hereinafter sometimes referred to as “approaching and separating force”). A vehicle suspension system including an approaching / separating force generating device that generates the controllable controllability has been studied.
JP 2000-225822 A JP 2002-218778 A JP 2002-211224 A JP 2006-82751 A

  In a suspension system including an absorber capable of changing the damping coefficient, the damping force is actively controlled according to the vibration of the vehicle body, the road surface condition, and the like. In addition, the suspension system including the approaching / separating force generating device is expected as a new active suspension system because the posture of the vehicle body such as a roll caused by turning of the vehicle can be actively controlled. These active suspensions are still under development, leaving plenty of room for improvement. Accordingly, it is possible to improve the practicality of the active suspension system by making various improvements. This invention is made | formed in view of such a situation, and makes it a subject to provide a highly practical vehicle suspension system.

  In order to solve the above-described problem, a vehicle suspension system according to the present invention includes a hydraulic absorber that has a mechanism for changing a damping coefficient and generates a damping force with respect to relative vibration between an upper part and an unsprung part. A system including an approaching / separating force generating device for controllably generating an approaching / separating force, wherein the approaching / separating force is changed before the damping coefficient is changed by the damping coefficient changing mechanism when the damping coefficient of the absorber is increased. The damping force is supplemented by using the approaching / separating force by the force generating device, and thereafter, the approaching / separating force is reduced, and the damping coefficient is increased by the damping coefficient changing mechanism.

  In the suspension system of the present invention, when the damping coefficient of the hydraulic absorber is increased, the damping coefficient changing mechanism is not suddenly operated, but first, a part of the damping force required when the damping coefficient is increased is obtained. In this case, the approach / separation force is generated by the approach / separation force generator. For this reason, it is possible to suppress an impact caused by the structure of the absorber when the damping force is suddenly increased by the operation of the damping coefficient changing mechanism. Then, after changing the damping coefficient by the damping force changing mechanism while reducing the approaching / separating force in a situation where the impact etc. is relatively small even if the damping coefficient is changed by the damping coefficient changing mechanism, It is possible to smoothly increase the damping capacity of the absorber.

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 each of the following items, (1) corresponds to claim 1, (2) corresponds to claim 2, (3) corresponds to claim 3, (6) corresponds to claim 4, (7) corresponds to claim 5 respectively.

(1) a suspension spring disposed between the sprung portion and the unsprung portion;
It is arranged in parallel with the suspension spring and generates a damping force against the relative vibration between the spring upper part and the unsprung part, and is its own ability to generate the damping force and the magnitude of the damping force A hydraulic type absorber having a damping coefficient changing mechanism for changing a damping coefficient serving as a reference of
A force that is arranged in parallel with the suspension spring, has an electric motor as a power source, depends on a force generated by the electric motor, and is a force in a direction to approach and separate the spring upper portion and the spring lower portion. An approaching / separating force generating device for generating an approaching / separating force;
A vehicle suspension system comprising: the damping coefficient changing mechanism and a control device for controlling the approaching / separating force generating device;
When the control device increases the damping coefficient of the absorber from the first damping coefficient to a second damping coefficient larger than the first damping coefficient, the damping force by the absorber is insufficient before the damping coefficient is changed by the damping coefficient changing mechanism. The approaching / separating force is generated in the approaching / separating force generating device to compensate for this, and then the approaching / separating force is reduced, and the damping coefficient of the absorber is changed to the second damping coefficient by the damping coefficient changing mechanism. A vehicle suspension system capable of executing control when the force-based damping coefficient is increased.

  The hydraulic type absorber is designed to generate a damping force by restricting the flow of hydraulic fluid in the absorber with the relative movement between the spring upper part and the spring unsprung part, and a mechanism for changing the damping coefficient is provided. If so, the mechanism is usually structured to change the flow area of the portion that provides resistance to the flow of hydraulic fluid. In such a structure, the flow passage area is reduced when the damping coefficient is increased, and therefore, when the flow of the hydraulic fluid is subjected to a sharp restriction, the absorber receives an impact, and abnormal noise is caused by the impact. , Abnormal vibration occurs. Such abnormal noise and abnormal vibrations impair driving comfort.

  Conventionally, as a countermeasure for such abnormal noise, for example, the damping coefficient is not changed at a time when a large impact is likely to occur in the absorber, and the damping coefficient is changed after waiting for the possibility to decrease. Such a method is adopted. However, when such a method is employed, the damping force is insufficient until the damping coefficient is changed even though a large damping force is required.

  In the aspect of this section, when increasing the damping coefficient of the absorber, the approaching / separating force is first generated by the approaching / separating force generating device, instead of suddenly changing the attenuation coefficient by the damping coefficient changing mechanism. The approaching / separating force bears a part of the damping force generated when the damping coefficient is increased, and supplements the necessary damping force. Therefore, according to the aspect of this section, it is possible to suppress an impact or the like generated in the absorber by operating the attenuation coefficient changing mechanism while suppressing an insufficient damping force by such an approaching / separating force. . Then, according to the aspect of this section, in a state where the damping force is supplemented by the approaching / separating force, for example, when the impact is relatively small even when the damping coefficient is changed by the damping coefficient changing mechanism, While the approaching / separating force is reduced, the damping coefficient can be increased by the damping coefficient changing mechanism, and by executing such a change in the damping coefficient, a large change is made in the absorber without a sudden change in the damping force. It is possible to change the damping coefficient without giving an impact. In other words, the suspension system of this aspect is configured to increase the damping capacity of the hydraulic absorber smoothly by temporarily generating an approaching / separating force that depends on the force of the electric motor as a damping force. is there.

  The “control at the time of increasing the damping coefficient using the approaching / separating force” described in this section (hereinafter sometimes simply referred to as “damping coefficient increasing control”) may be executed whenever the damping coefficient of the absorber is increased. In the case of increasing the damping coefficient of the absorber, for example, it may be executed on condition that the impact received by the absorber due to the increase of the damping coefficient, abnormal noise resulting from the impact, abnormal vibration, etc. are excessive.

  In the control at the time of increasing the damping coefficient described in this section, when the approaching / separating force is reduced and the damping coefficient is increased, the approaching / separating force may be reduced at once and the damping coefficient may be increased at once. May be gradually decreased and the attenuation coefficient may be gradually increased. In addition, when the approaching / separating force is generated to compensate for the shortage of the damping force by the absorber, the approaching / separating force may be generated so as to compensate for the shortage of the damping force by the absorber. An approaching / separating force may be generated so as to compensate for a part.

  The “attenuation coefficient changing mechanism” described in this section may be capable of continuously changing the attenuation coefficient, or may be capable of changing between a plurality of values set in stages. . In the former case, if the attenuation coefficient is gradually increased, it is possible to relatively reduce abnormal noise caused by the impact received by the absorber. On the other hand, in the latter case, the damping coefficient cannot be gradually increased by the damping coefficient changing mechanism. Therefore, the aspect of this section is suitable for a system that employs the damping coefficient changing mechanism having the latter structure.

  “Spring part” in this section means, for example, a part of a vehicle body supported by a suspension spring, and “sprung part” means, for example, a wide range of vehicle components that move up and down together with a wheel shaft, such as a suspension arm. means. The specific structure of the “suspension spring” is not particularly limited. For example, a spring having various structures such as a coil spring and an air spring can be adopted.

  The “approaching / separating force generator” described in this section is not particularly limited as long as it can controllably apply a force in a direction in which the sprung portion and the unsprung portion are approached / separated. The purpose of the approaching / separating force generator is not particularly limited. For example, it may be used exclusively in the damping coefficient increase control, or may be mainly intended to suppress the roll, pitch, etc. of the vehicle body, as will be described later. In the latter case, the approaching / separating force generator is used for a purpose other than the original purpose. That is, in the latter case, a smooth change in the damping capacity of the absorber is ensured by using the force generated by another existing device provided in the vehicle as the damping force. The “electric motor” provided as a power source in the approach / separation force generator may be a rotary motor or a linear motor.

(2) When the approach / separation force utilization damping coefficient is increased,
Prior to the change of the damping coefficient of the absorber by the damping coefficient changing mechanism, the approaching / separating force generator generates a damping force generated by the absorber when the damping coefficient is the second damping coefficient, and the damping coefficient is The vehicle suspension system according to item (1), which is control for generating an approaching / separating force corresponding to a difference from the damping force generated by the absorber when the damping coefficient is one.

  In this aspect, when the approaching / separating force is generated to compensate for the shortage of the damping force by the absorber in the above-described control at the time of increasing the damping coefficient, the approaching / separating force is generated so as to compensate for the shortage. According to the aspect of this section, for example, it is possible to suppress the occurrence of an impact when increasing the damping capacity of the absorber, an abnormal sound associated with the impact, etc. while maintaining a state in which a sufficient damping force is generated. It becomes.

  (3) A plurality of attenuation coefficients of the absorber are set in stages, and the attenuation coefficient changing mechanism changes from one of the plurality of attenuation coefficients to another one. Or the suspension system for vehicles as described in the item (2).

  In the attenuation coefficient changing mechanism according to the aspect of this section, as described above, the attenuation coefficient cannot be gradually changed. By controlling the operation of the attenuation coefficient changing mechanism, the attenuation coefficient is increased. It is difficult to sufficiently suppress the impact and abnormal noise of the absorber. In view of this, it can be said that the aspect of this section is an aspect in which the above-described control at the time of increasing the damping coefficient can be used particularly effectively.

  (4) When the damping force using the approaching / separating force increases when the damping force generated by the absorber is equal to or greater than a set threshold when the damping coefficient of the absorber is the second damping coefficient. The vehicle suspension system according to any one of items (1) to (3), configured to execute control.

  The mode described in this section is a mode in which a limitation is added with respect to the conditions for executing the above control at the time of increasing the damping coefficient. If the control at the time of increasing the damping coefficient is always executed when the damping coefficient of the absorber is increased, there is a risk that the power consumption by the approaching / separating force generator increases. The aspect of this section is based on such a situation, and is an aspect configured to execute the damping coefficient increase control only when there is a high possibility that the impact, abnormal noise, etc. of the absorber will increase. Note that the “setting threshold value” described in this section is a threshold value that allows the execution of the control when the approaching / separating force utilization damping coefficient is increased, and thus can be considered as a control execution allowable threshold value.

  (5) When the approaching / separating force utilization damping coefficient increasing control is performed, when the damping force generated by the absorber is equal to or less than a set threshold when the absorber damping coefficient is the second damping coefficient, the approaching / separating force is increased. The vehicle according to any one of (1) to (4), wherein the vehicle is control for reducing an approaching / separating force by a force generating device and changing a damping coefficient of the absorber to a second damping coefficient by the damping coefficient changing mechanism. Suspension system.

  The mode described in this section is a mode in which a limitation is imposed on the timing at which the approaching / separating force is reduced and the damping coefficient is increased in the above-described control when the damping coefficient is increased. According to the aspect of this section, the damping coefficient is changed by the damping coefficient changing mechanism at a timing at which an impact generated in the absorber is expected to be relatively small. The “setting threshold value” described in this section is a threshold value as a condition for permitting the change of the attenuation coefficient by the attenuation coefficient changing mechanism in the control when the attenuation coefficient is increased. it can. The value is not particularly limited, but it is desirable to set the value as small as possible in view of the generated impact or the like. For example, it can be set to 0.

  (6) The control device is configured to execute the approach / separation force utilization damping coefficient increasing control on condition that the relative speed between the sprung part and the unsprung part is equal to or higher than a set threshold speed (1) Item 4. The vehicle suspension system according to any one of Items (5) to (5).

  If the damping coefficient is increased by the damping coefficient changing mechanism in a state where the relative speed between the sprung part and the unsprung part is high, the impact generated on the absorber becomes relatively large. In view of this, the aspect of this section is an aspect configured to execute the damping coefficient increase control only when there is a high possibility that the impact, abnormal noise, etc. of the absorber will increase. Note that the “set threshold speed” referred to in this section is a threshold value that allows execution of control when the damping coefficient is increased, and can therefore be considered as a control execution allowable threshold value.

  (7) When the approaching / separating force utilization damping coefficient increasing control reduces the approaching / separating force by the approaching / separating force generating device when the relative speed between the sprung portion and the unsprung portion becomes equal to or lower than a set threshold speed, The vehicle suspension system according to any one of (1) to (6), wherein the damping coefficient of the absorber is changed to a second damping coefficient.

  The mode described in this section is a mode in which a limitation is imposed on the timing at which the approaching / separating force is reduced and the damping coefficient is increased in the above-described control when the damping coefficient is increased. According to the aspect of this section, the damping coefficient is changed by the damping coefficient changing mechanism at a timing at which an impact generated in the absorber is expected to be relatively small. The “set threshold speed” described in this section is a threshold value as a condition for permitting the change of the attenuation coefficient by the attenuation coefficient changing mechanism in the control when the attenuation coefficient is increased. Can do. The value is not particularly limited, but it is desirable to set the value as small as possible in view of the generated impact or the like. For example, it can be set to 0.

  (8) Car body attitude control in which the control device generates the approaching / separating force by the approaching / separating force generating device as at least one of a roll restraining force for restraining the roll of the vehicle body and a pitch restraining force for restraining the pitch of the vehicle body. The vehicle suspension system according to any one of (1) to (7), which is executable.

    The mode of this section is a mode in which a limitation relating to another function of the approaching / separating force generator is added. From another point of view, it can be considered as an aspect in which a limitation on the original function of the approaching / separating force generator is added. If the approaching / separating force generated by the approaching / separating force generating device is used as a vehicle body posture control force such as a roll restraining force or a pitch restraining force, active vehicle body posture control can be performed by actively controlling the approaching / separating force. . If the damping coefficient is increased during the execution of the vehicle body posture control, the approaching / separating force to be generated in the control when the damping coefficient is increased is added to the approaching / separating force as the posture control force. It is generated by the approach / separation force generator.

(9) The approaching / separating force generator is
An elastic body having one end connected to one of the spring top and the spring bottom;
The elastic body is disposed between the other end portion of the elastic body and the other of the spring upper portion and the spring lower portion, and connects the other and the elastic body. The electric motor is a component of the electric body, and the electric motor is The force generated by itself depending on the force to be generated is applied to the elastic body, thereby changing the deformation amount of the elastic body according to the amount of movement of itself, and the approaching / separating force via the elastic body. The vehicle suspension system according to any one of (1) to (8), further comprising: an electromagnetic actuator that acts on an upper part and an unsprung part.

  The mode described in this section is a mode in which the structure of the approaching / separating force generator is specifically limited. The “approaching / separating force generator” described in this section is configured to apply the force of the actuator to the elastic body and change the deformation amount of the elastic body in accordance with the operation amount of the actuator. Accordingly, in the aspect of 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 according to the amount of deformation. For example, an elastic body of various deformation forms such as a coil spring and a torsion spring should be adopted. Can do.

  In addition, in the above-described control at the time of increasing the damping coefficient, when the approaching / separating force is generated to compensate for the damping force by the absorber, the approaching / separating force may give an impact to the vehicle body at the time of the rising of the approaching / separating force. . However, in the approaching / separating force generating device according to the aspect of this section, the approaching / separating force is applied to the spring upper part and the spring lower part via the elastic body. It will be relaxed to some extent by the elastic body.

(10) A shaft portion in which the elastic body is rotatably held at the upper portion of the spring, and an arm portion extending from one end portion of the shaft portion so as to intersect the shaft portion and having a tip portion connected to the lower portion of the spring. Have
The vehicle suspension system according to item (9), wherein the actuator is fixed to a vehicle body and rotates the shaft portion around an axis thereof by a force generated by the actuator.

  The mode of this section is a mode in which the structure of the approach / separation 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 have a function as a torsion spring, or the arm portion may be bent to have a function as a spring. The elastic body may be a member in which the shaft portion and the arm portion are separate members, and may be combined, or may be configured as a single member formed by integrating them. Good.

(11) The ratio of the external input to the motor force required to actuate the actuator against the external input, which is a force acting on the actuator from the outside, is determined by the positive efficiency of the actuator and the external input. In the case where the ratio of the motor force required for the actuator not to be operated to the external input is defined as 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 (9) or (10), wherein the actuator has a structure having a forward / reverse efficiency product of 1/2 or less.

  The “normal / reverse efficiency product” in this section refers to the motor force required to operate the actuator against an external input of a certain magnitude and the motor required because the actuator cannot be operated by the external input. The smaller the forward / reverse efficiency product, the harder it is to move with respect to the external input.

  (12) The actuator has a speed reducer that decelerates the operation of the electric 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 (9) to (11).

  The aspect of this section is an aspect 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 electric 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 this point of view, the aspect of this section can be considered as a kind of aspect in which an actuator having a relatively small forward / reverse efficiency product is employed. If the reduction ratio of the reduction gear is increased, the electric motor can be reduced in size.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention includes various aspects in which various modifications and improvements have been made 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. 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 shock absorber (hereinafter sometimes abbreviated as “absorber”) 52, which are respectively provided in a tire housing which is a component part of the spring top. Between the provided mount portion 54 and the second lower arm 36 which is one component part of the unsprung portion, they are arranged in parallel with 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 electric motor 74. The electric motor 74 is fixedly accommodated in the motor case 76 and is fixed to the mount portion 54 by fixing the flange portion of the motor case 76 to the upper surface side of the mount portion 54. Further, the flange portion at the upper end of the piston rod 64 is also fixed to the flange portion of the motor case 76, and the piston rod 64 is fixed to the mount portion 54 by such a structure. 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 electric motor 74 at the upper end portion thereof. More specifically, an operation conversion mechanism 79 that converts rotation of the electric motor 74 into movement in the axial direction is provided below the electric 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 electric 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 above structure, for example, when 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 removed from the clearance of the connection passage 86 and the through hole 77. While flowing through 108 to the lower chamber 72, 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 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 allowed to flow through the connection passage 90 and the through hole 77. The air flows from the lower chamber 72 to the upper chamber 70 through the clearance 108 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 relative motion between the spring top and the spring bottom.

  Further, as described above, the adjustment rod 78 can be moved in the axial direction by the operation of the electric motor 74, and the size (width) of the clearance 108 of the through hole 77 can be changed. . 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 electric motor 74 and changes the clearance 108 thereof, so that a damping characteristic with respect to the relative motion between the spring top and the spring bottom, in other words, a so-called damping. The structure is such that the coefficient can be changed. More specifically, the electric 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 electric motor 74 is a stepping motor, and the rotation angle position at which the electric motor 74 is stopped is a position set in stages. Specifically, when the rotational angle position of the electric motor 74 is changed, the electric motor 74 is driven to rotate based on a command for rotating it by a predetermined number of steps. That is, three values are set as the attenuation coefficient of the absorber 52, and the absorber has a structure capable of changing the attenuation coefficient in three stages. In addition, this absorber 52 is provided with the attenuation coefficient change mechanism comprised by the electric motor 74, the through-hole 77, the adjustment rod 78, the connection channel | path 104, etc. by having the said structure.

  An annular lower retainer 110 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 110 and the upper retainer 114 in a state of 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. 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 move relatively to some extent in the direction in which the vehicle body and the wheel approach each other (hereinafter sometimes referred to as “bound direction”), the upper surface of the lid portion 66 passes through the anti-vibration rubber 112 and the piston rod 64 It comes into contact with the buttocks. 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.

  In addition, the suspension device 20 is a vehicle body wheel distance adjusting device (hereinafter also referred to as “adjusting device”) 120 that can adjust the distance between the vehicle body and the wheel (hereinafter also referred to as “vehicle body wheel distance”). Each of the adjusting devices 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 adjusting device 120 includes an electric motor 140 as a drive source and a speed reducer 142 that transmits the electric motor 140 at a reduced speed. The electric motor 140 and the speed reducer 142 are provided in a housing 144 which 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 electric 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 electric 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 electric 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 adjusting device 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 is configured as a harmonic gear mechanism. 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 electric 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 electric motor 140), and depends on the magnitude of this reduction ratio. In this actuator 126, the electric motor 140 is downsized. Also, depending on the reduction ratio, it is difficult to operate by an external input or the like.

  From the above configuration, when the electric motor 140 is driven, the L-shaped bar 122 is rotated by the motor force generated by the motor 140 and the shaft portion 130 of the L-shaped bar 122 is twisted. . 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, it acts as an approaching / separating force that is a force in a direction in which the vehicle body and the wheel are moved closer to and away from each other. 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. From this, it can be considered that the adjusting device 120 has a function as an approaching / separating force generating device that generates an approaching / separating force, and by adjusting the approaching / separating force, the distance between the vehicle body and the wheel. It is possible to adjust.

  As described above, the absorber 52 can change the magnitude of the damping force generated by itself. More specifically, it is possible to change the damping coefficient that is a reference for the magnitude of the damping force to be generated, that is, its own damping force generation capability. On the other hand, the adjusting device 120 generates an approaching / separating force that is a force in a direction in which the spring upper portion and the spring unsprung portion are approached / separated, 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, twists the shaft portion 130 of the L-shaped bar 122, and the actuator force is L-shaped. Through the bar 122, the spring upper part and the spring lower part are made to act as an approaching / separating force. 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 at least one of the operation amount of the actuator 126 and 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 electric 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 adjusting device 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 adjusting device 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 10, as shown in FIG. 1, an adjustment device electronic control unit (adjustment device ECU) 170 that executes control for the four adjustment devices 120 and an absorber electronic control unit that executes control for the 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 adjustment device ECU 170 is a control device that controls the operation of each actuator 126 included in each adjustment device 120, and includes four inverters 174 as a drive circuit corresponding to the electric motor 140 included in each actuator 126, CPU, ROM, and RAM. And an adjustment device 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 electric motor 74 provided in the absorber 52. The absorber is mainly composed of four motor drive circuits 178 as drive circuits and a computer having a CPU, ROM, RAM, and the like. And a controller 180 (see FIG. 18). 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 electric motor 140 of corresponding adjustment device 120, and motor drive circuit 178 Each is connected to the electric motor 74 of the corresponding absorber 52.

  Regarding the electric motor 140 included in the actuator 126 of the adjusting device 120, the electric motor 140 is driven at a constant voltage, and the amount of power supplied to the electric 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).

  In addition to the motor rotation angle sensor 154, the adjustment device controller 176 includes a steering sensor 190 for detecting an operation angle of the steering wheel, which is an operation amount of the steering operation member as a steering amount, and a lateral force actually generated in the vehicle body. A lateral acceleration sensor 192 that detects actual lateral acceleration, which is an acceleration, a longitudinal acceleration sensor 194 that detects longitudinal acceleration generated in the vehicle body, and a stroke sensor 198 that detects the distance between vehicle body wheels are connected. The adjusting device 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 adjusting device controller 176 acquires the vehicle speed from the brake ECU 200 as necessary. Further, the adjustment device controller 176 is connected to each inverter 174 and controls each adjustment device 120 by controlling them. Note that the ROM included in the computer of the adjustment device controller 176 stores a program related to the control of each adjustment device 120 described later, various data, and the like.

  On the other hand, the stroke sensor 198 is connected to the absorber controller 180. Furthermore, the absorber controller 180 is also connected to each motor drive circuit 178, and controls the electric motor 74 of 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 described later, various data, and the like. Incidentally, the adjusting device controller 176 and the absorber controller 180 are connected to each other so as to be able to communicate with each other, and information, commands, etc. relating to the control of the suspension system 10 are communicated as necessary.

≪Normal efficiency and reverse efficiency of the actuator of the adjustment device≫
Here, the efficiency of the actuator 126 included in the adjusting device 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 simply referred to as “reverse efficiency”) η _N is defined as the ratio of the minimum motor force at which the electric motor 140 cannot be rotated by an 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, assuming that 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 electric motor 140 is Fm, 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 actuators Fa of the same size are generated, the motor force Fm _P of the electric 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 relative to the motor force Fm _P of the electric 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 electric motor 140 as compared to the case where the actuator 126 is operated against the external input, for example, when the operation position is maintained under the action of the external input. Making it possible. Since it can be considered that the motor force is proportional to the power supplied to the electric motor, the power consumption is greatly reduced in the actuator 126 having a small forward / reverse efficiency product η _P · η _N.

≪Control of vehicle suspension system≫
i) Basic control of the adjusting device In the present suspension system 10, control for suppressing the roll of the vehicle body (hereinafter referred to as "roll suppressing control") by independently controlling the approaching / separating force generated by each adjusting device 120. Control for suppressing the pitch of the vehicle body (hereinafter sometimes referred to as “pitch suppression control”). In the present system 10, control in which these two controls are combined is generally performed. In this control, each adjusting device 120 controls the motor rotation angle of the electric motor 140 so as to exert an appropriate approaching / separating force based on the roll moment and pitch moment received by the vehicle body. More specifically, an electric motor is determined such that a target motor rotation angle, which is a target motor rotation angle, is determined based on a roll moment, a pitch moment, and the like received by the vehicle body, and the actual motor rotation angle becomes the target motor rotation angle. 140 is controlled. Note that the roll suppression control and the pitch suppression control control the posture of the vehicle body, and thus can be considered as a kind of vehicle body posture control.

In the present system 10, the target motor rotation angle described above is determined by adding the target motor rotation angle components for each control of roll suppression control and pitch suppression control. The components for each control are
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 the roll suppression control and the pitch suppression control will be described in detail with a focus on the determination method of each target motor rotation angle component, and the determination of power supplied to the electric motor 140 based on the target motor rotation angle will be described. explain in detail.

a) Roll suppression control In roll suppression control, when the vehicle is turning, the adjusting device 120 on the inner side of the turning has an approaching / separating force in the bounce direction and the adjusting device on the outer side of the turning according to the roll moment resulting from the turning. In 120, the approaching / separating force in the rebound direction is exhibited as a roll restraining 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 _A · Gyc + K _B · Gyr (K _A , K _B : gain)
Then, the roll suppression component θ ^* _R is determined based on the determined control lateral acceleration Gy ^* . In the controller 176 of the adjusting device ECU 170, map data of the roll suppression component θ ^* _R having the control lateral acceleration Gy ^* as a parameter is stored, and the map data is referred to in determining the roll suppression component θ ^* _R. Is done.

b) Pitch Suppression Control In the pitch suppression control, the front wheel side adjusting device 120 has an approaching / separating force in the rebound direction according to the pitch moment that causes the nose dive to occur when braking the vehicle body. In the rear wheel side adjusting device 120, the approaching / separating force in the bound direction is generated as a pitch restraining 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 approaching / separating force in the rebound direction is applied to the adjustment device 120 on the front wheel side according to the pitch moment that generates the squat. Generates an approaching / separating force in the bounce direction as a pitch restraining 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 _C · Gzg (K _C : Gain)

c) Determination of Target Supply Current As described above, when the roll suppression component θ ^* _R and the pitch suppression component θ ^* _P are determined, the target motor rotation angle θ ^* is determined according to the following equation.
θ ^* = θ ^* _R + θ ^* _P
Then, the electric motor 140 is controlled such that the actual motor rotation angle θ, which is the actual motor rotation angle, becomes the target motor rotation angle rotation angle θ ^* . In the control of the electric motor 140, the electric power supplied to the electric 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 supply current motor rotation angle deviation Δθ. Specifically, first, the motor rotation angle deviation Δθ is certified based on the detection value of the motor rotation angle sensor 154 included in the electric motor 140, and then, using it as a parameter, the target supply current i ^* according to the following equation: 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 electric 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 electric 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 roll suppression when the vehicle performs a typical one-turn operation, as shown in FIG. 9, the roll suppression force to be generated by the adjusting device 20, that is, the approaching / separating force is changed. The target motor rotation angle θ ^* of the 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 integral term current component i _S according to the motor rotation angle deviation Δθ is performed. In particular, at the beginning of turning [a], since the actuator 126 must be operated against an external input, the electric motor 140 generates a current that is large enough to generate a motor force that exceeds the motor force according to the positive efficiency characteristics. 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 electric 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 represents the direction of generation of the motor force of the electric motor 140 by its sign, and the drive control of the electric motor 140 is based on the target supply current i ^* . A duty ratio and a motor force generation direction for driving electric motor 140 are determined. Then, commands regarding the duty ratio and the direction in which the motor force is generated are issued to the inverter 174, and the inverter 174 performs drive control of the electric motor 140 based on the commands.

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) Basic control of the damping coefficient of the absorber As described above, the absorber 52 has a damping force having a magnitude corresponding to the relative speed between the sprung portion and the unsprung portion relative to the relative movement between the sprung portion and the unsprung portion. Is generated. The absorber 52 generates a damping force having a magnitude based on the damping coefficient set therein. Therefore, the damping coefficient is an index of the ability of the absorber to generate a damping force. On the other hand, the value of the damping coefficient affects the transmission of vibration from the unsprung portion to the unsprung portion, the grounding property of the wheel, and the like. Specifically, as shown in FIG. 10, the transmission of vibrations in the sprung resonance frequency region is lower as the damping coefficient is larger, while the sprung resonance frequency region and the unsprung resonance frequency region are lower. The transmission of vibrations in the frequency range between them increases as the damping coefficient increases. Further, as shown in FIG. 11, the ground load fluctuation rate with respect to the vibration of the unsprung resonance frequency is higher as the damping coefficient is smaller. The ground load variation rate and the wheel grounding property are in a relative relationship, and the higher the ground load variation rate, the lower the wheel grounding property. Therefore, the grounding property against vibration in the unsprung resonance frequency range has a small damping coefficient. It gets lower.

As described above, the absorber 52 of the suspension system 10 has a structure in which the damping coefficient can be changed in three stages. Damping coefficient of the absorber 52, the standard is an attenuation coefficient setting standard damping coefficient C _M, set the standard damping coefficient C _M larger is set as the damping coefficient set high damping coefficient C _H, a smaller set standard damping coefficient C _M Three set low attenuation coefficients C _L set as attenuation coefficients are set, and the attenuation coefficient of the absorber 52 is selected from the three set attenuation coefficients C _L , C _M , and C _H by the control. Will be changed.

If the damping coefficient of the absorber 52 to be realized by control is the target damping coefficient C ^* , the target damping coefficient C ^* is normally set to the set standard damping coefficient C _M , but vibration in the sprung resonance frequency range is If this occurs, the target damping coefficient C ^* is set to the set high damping coefficient C _H in order to reduce the transmission of vibration from the unsprung portion to the unsprung portion, and between the sprung resonance frequency region and the unsprung resonance frequency region. In the case where vibration in the frequency range occurs, the target damping coefficient C ^* is set to the set low damping coefficient C _L. To determine which frequency range the relative vibration between the sprung part and the unsprung part is, the vibration component is calculated for each frequency range by filtering from the relative vibration between the sprung part and the unsprung part. Compare the magnitude of the vibration component in each frequency range. Specifically, first, based on the vehicle body wheel distance X detected by the stroke sensor 198, the longitudinal acceleration Gs for the relative vibration is calculated. Next, based on the calculated longitudinal acceleration Gs, filter processing for the sprung resonance frequency range is executed to calculate the first vibration component amount S ₁ in the sprung resonance frequency range, and the sprung resonance frequency range and Filter processing is performed for a frequency range between the unsprung resonance frequency range and a second vibration component amount S ₂ in the frequency range between the unsprung resonance frequency range and the unsprung resonance frequency range is calculated. When the first vibration component S ₁ is equal to or greater than the set threshold value S ₁₀ , it is determined that vibration in the sprung resonance frequency region has occurred, and the target damping coefficient C ^* is set to the set high damping coefficient in principle. C _H. Further, when the second vibration component amount S ₂ is equal to or greater than the set threshold value S ₂₀ , it is determined that vibration in the frequency region between the sprung resonance frequency region and the unsprung resonance frequency region is generated, and the target damping is performed. The coefficient C ^* is set to the set low attenuation coefficient C _{L in} principle. However, when the first vibration component amount S ₁ is equal to or greater than the set threshold value S ₁₀ and the second vibration component amount S ₂ is equal to or greater than the set threshold value S ₂₀ , it is determined that vibrations in either frequency range have occurred. The target attenuation coefficient C ^* is set as the set standard attenuation coefficient C _M. FIG. 12 shows the relationship between the first vibration component amount S ₁ , the second vibration component amount S _2, and the target damping coefficient C ^* .

In the control of the damping coefficient of the absorber 52, the vibration component in the unsprung resonance frequency region of the relative vibration between the sprung portion and the unsprung portion is also taken into consideration in order to prevent a reduction in the grounding property of the wheel. In detail, based on the longitudinal acceleration Gs, executes the filtering process on the unsprung resonance frequency range, calculating a third vibration component quantity S _H of the unsprung resonance frequency range, the third vibration component quantity S _H Is _{equal to} or greater than the set threshold value S _H0 , the target attenuation coefficient C ^* is not set to the set low attenuation coefficient C _L. That is, when the target attenuation coefficient C ^* is the set low attenuation coefficient C _L , the target attenuation coefficient C ^* is changed to the set standard attenuation coefficient C _M.

iii) Control at the time of increasing the damping coefficient using the approaching / separating force Since the absorber 52 generates a damping force having a magnitude corresponding to the relative speed Vs between the spring upper part and the spring lower part, the damping force F generated by the absorber 52 and the relative speed are generated. The relationship with Vs is as shown in FIG. In the figure, the relationship between the damping force and the relative velocity corresponding to each of the set three types of damping coefficients C _L , C _M , and C _H is shown. For example, when the target damping coefficient C ^* is changed from the set low damping coefficient C _L to the set standard damping coefficient C _M and the damping coefficient of the absorber 52 is increased, the amount of increase in the damping force accompanying the change in the damping coefficient (solid line) As shown in the figure, the arrow (arrow) increases as the relative speed increases. This is the same when the target attenuation coefficient C ^* is changed from the set low attenuation coefficient C _L to the set high attenuation coefficient C _H or when the target standard attenuation coefficient C _M is changed to the set high attenuation coefficient C _H. It is. Therefore, when the damping coefficient of the absorber 52 is increased when the relative speed between the sprung portion and the unsprung portion is high, a relatively large impact is generated on the absorber 52, and accordingly, abnormal noise, abnormal vibration, or the like may occur. is there.

In controlling the damping coefficient of the absorber 52, the electric motor 74 is controlled according to the target damping coefficient C ^*, and the vertical position of the conical portion 106 of the adjusting rod 78 is adjusted, whereby the clear lath in the through hole 77 is adjusted. The size (width) of 108 is adjusted. More specifically, the clearance 108 becomes smaller as the damping coefficient of the absorber 52 becomes larger. That is, when the attenuation coefficient of the absorber 52 is increased, the clearance 108 in the through hole 77 is changed from a large state to a small state. At this time, if the speed at which the piston 62 moves up and down in the housing 60 is high, in other words, if the speed of the hydraulic fluid passing through the clearance 108 is high, a relatively large impact is generated on the absorber 52, Along with this, there is a possibility that abnormal noise, abnormal vibration, etc. may occur.

  Therefore, when increasing the damping coefficient of the absorber 52, if the moving speed of the piston 62, that is, the relative speed between the upper part of the spring and the lower part of the spring is high, the damping coefficient of the absorber 52 is not changed. When the relative speed between the upper part and the unsprung part becomes low, the damping coefficient of the absorber 52 is changed. However, in the state before the damping coefficient is increased, the absorber 52 originally does not generate the damping force that should be generated, and the damping characteristic with respect to the relative vibration between the sprung portion and the unsprung portion is appropriate. There is a risk of not becoming. Therefore, in the period before the damping coefficient of the absorber 52 is changed, the approaching / separating force by the adjusting device 120 is used to compensate for the damping force that the absorber 52 should generate. That is, in the present system 10, when the damping coefficient of the absorber 52 is increased, the absorber 52 is generated prior to the change of the damping coefficient of the absorber 52 on condition that the relative speed between the sprung portion and the unsprung portion is high. The approaching / separating force is generated so as to compensate for the damping force, and then the approaching / separating force by the adjusting device 120 is reduced and the damping coefficient of the absorber 52 is actually set when the relative speed between the sprung portion and the unsprung portion becomes low. (Hereinafter, referred to as “control when the approaching / separating force is used to increase the damping coefficient” or abbreviated as “control when the damping coefficient is increased”).

As a specific example, when there is a request to increase the damping coefficient of the absorber 52, more specifically, before the increase, that is, from the first damping coefficient C ₁ that is the damping coefficient at the present time, the second damping coefficient C ₂ that is larger than that. Consider a case where there is a request for changing the target damping coefficient C ^* to (C ₂ > C ₁ ). In this system, the damping number increase control is executed on the condition that the relative speed Vs between the sprung portion and the unsprung portion at the time when the damping coefficient increase is requested is equal to or higher than the first set threshold speed Vs _1. .

In the damping coefficient increase control in this system, the damping coefficient of the absorber 52 is maintained as the first damping coefficient C ₁ without immediately responding to the increase request. In this state, the adjusting device 120 generates an approaching / separating force so as to assist the damping force. Specifically, first, when the damping coefficient is the second damping coefficient C ₂ that is the target damping coefficient C ^* , the target damping force F ^* that is the damping force that the absorber 52 should generate, and the current damping the difference between the first in the attenuation coefficient C ₁ is a damping force absorber 52 is generating a real damping force F _R is a coefficient, insufficient damping force ΔF is calculated, displacement force corresponding to the shortage damping force ΔF is, It is generated by the adjustment device 120.

More specifically, the target damping force F ^* is determined according to the following equation in order to attenuate the relative vibration between the sprung portion and the unsprung portion according to the target damping coefficient C ^* .
F ^* = C ^*・ Vs
The actual damping force F _R is determined according to the following equation in order to attenuate the relative vibration between the sprung portion and the unsprung portion according to the actual damping coefficient C _R that is the actual damping coefficient of the absorber 52 that has not been changed.
F _R = C _R · Vs
Then, based on the determined target damping force F ^* and to the actual damping force F _R, insufficient damping force ΔF is determined according to the following equation.
ΔF = F ^* −F _R

In the control of the adjusting device 120 for generating the insufficient damping force ΔF, first, based on the determined insufficient damping force ΔF, the electric motor included in the actuator 126 as a control target value for generating the insufficient damping force ΔF. 140 damping force rotation angle components θ ^* _G are determined according to the following equation.
θ ^* _G = K _E · F _HG (K _E : Gain)
Next, based on the determined damping force rotation angle component θ ^* _G , the roll suppression component θ ^* _R, and the pitch suppression component θ ^* _P , the target motor rotation angle θ ^* is determined according to the following equation.
θ ^* = θ ^* _G + θ ^* _R + θ ^* _P
Based on the determined target motor rotation angle θ ^* , the target supply current i ^* is determined according to the above equation according to the PI control law, and the target supply current i ^* is supplied to the electric motor 140, thereby adjusting device 120. The dampening force that is insufficient is compensated for by the approaching / separating force generated by.

In the present system, when the relative speed Vs is equal to or lower than the second set threshold speed Vs ₂ (Vs ₂ <Vs ₁ ) in the state where the assist of the damping force by the adjustment device 120 is executed as described above, At that time, the control of the adjusting device 120 based on the insufficient damping force ΔF is stopped, and the damping coefficient of the absorber 52 is changed from the maintained first damping coefficient C ₁ to the current target damping coefficient C 1. a ^* is changed to the second damping coefficient C _2. Thereby, when the impact on the absorber 52 becomes small, the damping coefficient of the absorber 52 is changed, and the requested damping force is applied by the absorber 52 without assistance by the approaching / separating force of the absorber 52 adjusting device 120. Will be generated.

For example, let us consider a case in which a periodic vibration is generated in the vehicle and there is a request to increase the damping coefficient of the absorber 52. The vibration assumes that the relative speed Vs between the sprung portion and the unsprung portion changes as shown in FIG. The damping force F generated by the absorber 52 with respect to such vibrations changes as shown in FIG. 14B according to the relative speed Vs. The damping force F varies depending on the magnitude of the damping coefficient of the absorber 52, and in the figure, the damping force corresponding to each of the three set damping coefficients C _L , C _M , and C _H is shown. It shows a change.

In this example, as shown in FIG. 14C, consider a case where the target attenuation coefficient C ^* is changed from the set low attenuation coefficient C _L to the set standard attenuation coefficient C _H at time t ₁ . Since the absolute value of the relative velocity Vs is in the first set threshold speed Vs ₁ or more at time t _1, despite the increase in demand, the damping coefficient of the absorber 52, the setting a low damping coefficient C _L Maintained. In this state, the adjusting device 120 causes the approaching / separating force corresponding to the insufficient damping force ΔF (hatched line) corresponding to the difference between the target damping force F ^* (two-dot chain line) and the actual damping force F _R (solid line). Be generated. Thereafter, at time t ₂ when the absolute value of the relative speed Vs becomes equal to or less than the second set threshold speed Vs _{2, the} approaching / separating force by the adjusting device 120 is reduced, and the damping coefficient of the absorber 52 is set to the set high damping coefficient C. Increased to _H.

In the present system 10, a condition relating to the relative speed Vs between the sprung part and the unsprung part is employed as a condition for executing the control at the time of increasing the damping coefficient and a condition for actually increasing the damping coefficient. And the damping force generated by the absorber 52 are in a proportional relationship, the condition relating to the damping force generated by the absorber 52 may be adopted as the above condition. More specifically, when there is a request for increasing the damping coefficient of the absorber 52, the absorber 52 executes the damping coefficient increasing control on the condition that the damping force that should originally be generated is large, and the absorber 52 generates it. When the power damping force decreases, the approaching / separating force may be reduced and the damping coefficient of the absorber 52 may be increased. Specifically, on condition that the absolute value of the target damping force F ^* is a first preset threshold F ₁ or more, running time control increase the damping coefficient, the absolute value of the target damping force F ^* is the At the time when the value becomes equal to or less than 2 setting threshold F ₂ (F ₂ <F ₁ ), the approaching / separating force as the insufficient damping force ΔF may be reduced and the damping coefficient of the absorber 52 may be increased.

  In the control of the damping coefficient of the absorber 52 in the present system 10, the damping coefficient of the absorber 52 is changed according to the frequency range of relative vibration between the spring top and the spring bottom, but depending on the road surface condition on which the vehicle travels, You may change the attenuation coefficient of an absorber. Specifically, for example, when the vehicle travels on a wavy road, there is a risk that the vehicle body may be distorted and the stability of the vehicle body may be impaired. Therefore, the absorber is set to a high damping coefficient, and the vehicle is rugged. When traveling on the vehicle, the occupant may feel a harsh feeling and the ride comfort may deteriorate. Therefore, the attenuation coefficient may be controlled so that the attenuation coefficient of the absorber is set lower. The determination of the undulating road, the rugged road, etc. can be made based on the sprung longitudinal acceleration or the like. Further, the absorber 52 of the system 10 can change the attenuation coefficient in three stages, but employs an absorber that can change the attenuation coefficient in more stages, for example, five stages, seven stages, nine stages, etc. By doing so, fine control is possible.

≪Control program≫
In this system, the damping coefficient of the absorber 52 is controlled by the absorber controller 180 executing the absorber control program shown in the flowchart of FIG. On the other hand, the approaching / separating force generated by the adjusting device 120 is controlled by the adjusting device controller 176 executing the adjusting device control program shown in the flowchart of FIG. These two programs are repeatedly executed at short time intervals (for example, several milliseconds) while the ignition switch is in the ON state, and are executed in parallel. Below, the flow of each control is demonstrated easily, referring the flowchart shown in a figure. The absorber control program is executed for each of the four absorbers 52, and the adjustment device control program is executed for each actuator 126 of the four adjustment devices 120. In the following description, control processing for one absorber 52 and control processing for one actuator 126 will be described in consideration of simplification of the description.

i) Absorber control program In the process according to this program, first, in step 1 (hereinafter simply referred to as “S1”. The same applies to other steps), a target damping coefficient determination subroutine shown in the flowchart of FIG. 16 is executed. Processing for this is executed. First, in S21, the vehicle body wheel distance X is detected based on the stroke sensor 198, and in S22, the longitudinal acceleration Gs for the relative vibration between the sprung portion and the unsprung portion is calculated based on the vehicle wheel distance X. . Then, calculated in S23 to S25, based on the longitudinal acceleration Gs, running filtering of each frequency band, the first vibration component quantity S _1, the second vibrating component quantity S _2, a third vibration component quantity S ₃ To do. Subsequently, in S26 to S32, as described above, the target damping coefficient C ^* is determined based on the vibration component amounts S ₁ , S ₂ , S ₃ .

After execution of the subroutine, followed by step S2 of the main routine, and have been determined target damping coefficient C ^*, whether the damping coefficient of the actual absorber 52 C _R are the same is determined, it is different from that determined If, in S3, whether the target damping coefficient C ^* is greater than the actual damping coefficient C _R is determined. When the target damping coefficient C ^* is determined to be greater than the actual damping coefficient C _R, in S4, based on the vehicle wheel distance X, relative velocity Vs of the sprung portion and the unsprung portion is calculated in S5, It is determined whether or not the absolute value of the relative speed Vs is equal to or higher than the first set threshold speed Vs ₁ . If it is determined that the absolute value of the relative speed Vs is equal to or higher than the first set threshold speed Vs ₁ , the damping coefficient increase temporary prohibition flag G indicating that the increase of the attenuation coefficient of the absorber 52 is temporarily prohibited in S6. The flag value is set to 1. When the flag value of the flag G is 1, it indicates that the increase of the attenuation coefficient is temporarily prohibited, and when it is 0, it indicates that the increase of the attenuation coefficient is not prohibited. ing.

In S5, the absolute value of the relative velocity Vs is a case where it is determined that the first set threshold speed Vs less than _1, in S7, whether or not the flag value of the attenuation coefficient increase temporary prohibition flag G is 1 is determined , when the flag value of the flag G is 0, at S8, the absolute value of the relative velocity Vs is whether the second set threshold speed Vs ₂ or less is determined. When it is determined that the absolute value of the relative speed Vs is equal to or less than the second set threshold speed Vs ₂ , after the flag value of the attenuation coefficient increase temporary prohibition flag G is set to 0 in S9, or in S7, the attenuation coefficient increases. If it is determined that the flag value of the temporary prohibition flag G is 0, or if it is determined in S3 that the target damping coefficient C ^* is smaller than the actual damping coefficient C _R , the actual damping is performed in S10. The coefficient C _R is set as the target damping coefficient C ^* . In S11, after a control signal based on the determined target attenuation coefficient C ^* is transmitted to the motor drive circuit 178, one execution of this program ends.

ii) Adjustment device control program In the processing according to this program, first, in S41, a roll suppression component θ ^* _R for roll suppression control is determined based on the above-described control lateral acceleration, and then in S42, the longitudinal acceleration is determined. Based on the above, a pitch suppression component θ ^* _P for pitch suppression control is determined.

Next, in S43, it is determined whether or not the adjusting device 120 needs to generate an approaching / separating force as the insufficient damping force ΔF. The adjusting device 120 needs to generate an approaching / separating force as the insufficient damping force ΔF when an increase in the damping coefficient of the absorber 52 is temporarily prohibited. Specifically, it is determined whether or not the flag value of the damping coefficient increase temporary prohibition flag G determined by the above-described absorber control program is set to 1. Information regarding the flag G is acquired from the absorber controller 180 by the adjusting device controller 176 as necessary. When it is determined that the flag value of the flag G is set to 1, the vehicle body wheel distance X is detected based on the stroke sensor 198 in S44, and based on the vehicle body wheel distance X in S45. The relative speed Vs between the sprung portion and the unsprung portion is calculated. Next, in S46, according to the target damping coefficient C ^*, is determined target damping force F ^*, in S47, in accordance with the actual damping coefficient C _R, the actual damping force F _R is determined. They target damping coefficient C ^*, information about the actual damping coefficient C _R, the adjusting device controller 176 obtains optionally from the absorber controller 180.

Subsequently, in S48, based on the target damping force F ^* and the actual damping force F _R, underdamped force [Delta] F is calculated in S49, based on the lack of damping force [Delta] F, the damping force directed subcomponent theta ^* _G Calculated. In S50, the target motor rotation angle θ ^* is determined by adding the damping force rotation angle component θ ^* _G , the roll suppression component θ ^* _R, and the pitch suppression component θ ^* _P. If the flag value of the damping coefficient increase temporary prohibition flag G is determined to be 0 in S43, the roll suppression component θ ^* _R and the pitch suppression component θ ^* _P are summed in S51, A target motor rotation angle θ ^* is determined. When the target motor rotation angle θ ^* is determined, in S52, the target supply current i ^* is determined based on the determined target motor rotation angle θ ^* according to the above-described formula according to the PI control law, and is determined in S53. After the control signal based on the target supply current i ^* is transmitted to the inverter 174, one execution of this program ends.

≪Functional structure of controller≫
The absorber controller 180 that executes the above-described absorber control program can be considered to have a functional configuration as shown in FIG. 18 in view of its execution processing. As will be understood from the figure, the absorber controller 180 uses the target damping coefficient determination unit 220 as a function unit that executes the processing of the target damping coefficient determination subroutine, that is, a function unit that determines the target damping coefficient C ^* of the absorber 52. A function for executing the process of step S5, that is, a function for executing the processes of S5 and S6 as a function part for changing the attenuation coefficient of the absorber 52 based on the determined target attenuation coefficient C ^*. Part, that is, a function unit for temporarily prohibiting an increase in the attenuation coefficient of the absorber 52, respectively, has an attenuation coefficient increase temporary prohibition unit 224. Further, the absorber controller 180 includes an attenuation coefficient increase temporary prohibition canceling unit 226 as a functional unit that executes the processes of S8 and S9, that is, a functional unit that cancels temporary increase of the attenuation coefficient of the absorber 52. .

Further, the adjustment device controller 176 that executes the adjustment device control program can be considered to have a functional configuration as shown in FIG. 18 in view of the execution process. As can be seen from the figure, the adjustment device controller 176 uses the damping force component determination unit 228 as a function unit that executes the processes of S44 to S49, that is, a function unit that determines the damping force component θ ^* _G. As a functional unit that executes processing, that is, a functional unit that determines the roll suppression component θ ^* _R and the pitch suppression component θ ^* _P , the vehicle body posture control component determination unit 230 is used as a functional unit that executes the processes of S50 to S52, that is, The vehicle body posture control execution unit 232 is provided as a functional unit that executes roll suppression control and pitch suppression control. Furthermore, the adjusting device controller 176 has a damping force shortage assisting unit 234 as a function unit that executes the processes of S50 and S52, that is, a functioning unit that assists in the lack of damping force by the absorber 52. The attenuation coefficient increase temporary prohibition unit 224, the attenuation coefficient increase temporary prohibition release unit 226, and the damping force shortage auxiliary unit 234 have a function of executing the approach / separation force utilization damping coefficient increase control, and therefore, these three functional units. 224, 226, and 234 can be considered to constitute the control execution unit when the approaching / separating force utilization damping coefficient is increased.

≪Another absorber control program≫
In this system 10, the damping coefficient of the absorber 52 is controlled by executing the absorber control program shown in the flowchart of FIG. 15, but the second absorber control program shown in the flowchart of FIG. 19 is executed. Thus, the damping coefficient of the absorber may be controlled. As described above, the processing according to the second absorber control program includes the damping force as the execution condition of the damping coefficient increasing control using the approaching / separating force and the condition for actually increasing the damping coefficient in the control. This is a process that employs the conditions regarding. Specifically, the absolute value of the target damping force F ^* (S65) is, when the first preset threshold F ₁ or more (S66), an increase of the damping coefficient of the absorber 52 is temporarily prohibited, the target damping When the absolute value of the force F ^* becomes equal to or less than the second set threshold F ₂ (S69), the damping coefficient of the absorber 52 is increased.

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 adjustment apparatus with which a suspension apparatus is provided. 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 graph which shows notionally the relationship between a vibration frequency and the transmissibility of the vibration from a spring lower part to a spring upper part. 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 table | surface which shows the relationship between the 1st vibration component amount, the 2nd vibration component amount, and a target damping coefficient. It is a graph which shows harmfully the relationship between the relative speed of a spring upper part and a spring lower part, and the damping force which an absorber generates. It is a chart which shows roughly change with time passage of relative speed of an upper part and unsprung part, absorber damping force, and target damping force. It is a flowchart which shows an absorber control program. It is a flowchart which shows the target damping coefficient determination subroutine performed in an absorber control program. It is a flowchart which shows an adjustment apparatus control program. It is a block diagram which shows the function of the control apparatus which manages control of an adjustment apparatus and an absorber. It is a flowchart which shows the 2nd absorber control program made executable in the suspension system for vehicles of a modification.

Explanation of symbols

  10: Vehicle suspension system 36: Second lower arm (lower spring) 50: Coil spring (suspension spring) 52: Absorber 54: Mount part (upper spring) 74: Electric motor (damping coefficient changing mechanism) 77: Through hole (damping) 78: Adjustment rod (damping coefficient changing mechanism) 79: Motion conversion mechanism (damping coefficient changing mechanism) 120: Vehicle wheel distance adjusting device (approaching / separating force generating device) 122: L-shaped bar (elastic body) 126 : Actuator 130: Shaft part 132: Arm part 140: Electric motor 142: Reducer 170: Adjustment device

Claims (5)

A suspension spring disposed between the spring top and the spring bottom;
It is arranged in parallel with the suspension spring and generates a damping force against the relative vibration between the spring upper part and the unsprung part, and is its own ability to generate the damping force and the magnitude of the damping force A hydraulic type absorber having a damping coefficient changing mechanism for changing a damping coefficient serving as a reference of
A force that is arranged in parallel with the suspension spring, has an electric motor as a power source, depends on a force generated by the electric motor, and is a force in a direction to approach and separate the spring upper portion and the spring lower portion. An approaching / separating force generating device for generating an approaching / separating force;
A vehicle suspension system comprising: the damping coefficient changing mechanism and a control device for controlling the approaching / separating force generating device;
When the control device increases the damping coefficient of the absorber from the first damping coefficient to a second damping coefficient larger than the first damping coefficient, the damping force by the absorber is insufficient before the damping coefficient is changed by the damping coefficient changing mechanism. The approaching / separating force is generated in the approaching / separating force generating device to compensate for this, and then the approaching / separating force is reduced, and the damping coefficient of the absorber is changed to the second damping coefficient by the damping coefficient changing mechanism. A vehicle suspension system capable of executing control when the force-based damping coefficient is increased. Control when the approaching / separating force utilization damping coefficient is increased,
Prior to the change of the damping coefficient of the absorber by the damping coefficient changing mechanism, the approaching / separating force generator generates a damping force generated by the absorber when the damping coefficient is the second damping coefficient, and the damping coefficient is 2. The vehicle suspension system according to claim 1, wherein control is performed to generate an approaching / separating force corresponding to a difference from the damping force generated by the absorber when the damping coefficient is one.   3. The damping coefficient of the absorber is set in a plurality of stages, and the damping coefficient changing mechanism changes from one of the plurality of damping coefficients to another one. The vehicle suspension system described in 1.   2. The control device according to claim 1, wherein the controller is configured to execute the approach / separation force utilization damping coefficient increasing control on condition that a relative speed between the sprung part and the unsprung part is equal to or higher than a set threshold speed. 4. The vehicle suspension system according to any one of 3 above.   When the approaching / separating force utilization damping coefficient increase control is performed, when the relative speed between the spring upper part and the unsprung part becomes equal to or lower than a set threshold speed, the approaching / separating force generator reduces the approaching / separating force, and the absorber The vehicle suspension system according to any one of claims 1 to 4, wherein control is performed to change the damping coefficient to a second damping coefficient.

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