JP4872686B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a vehicle suspension system provided with a device that controllably generates a force for moving an upper and lower springs close to and away from each other by operation of an electromagnetic actuator.

In recent years, a suspension system for a vehicle as described in the following patent document, more specifically, a force (hereinafter referred to as “approaching and separating”) that relies on the operation of an electromagnetic actuator to move the sprung portion and the unsprung portion closer. A system in which an approaching / separating force generating device that generates controllable force (sometimes referred to as “force”) in parallel with a suspension spring and a shock absorber (hereinafter also referred to as “absorber”) has begun to be studied. In this system, the roll of the vehicle body can be suppressed by applying the approaching / separating force as a roll suppressing force for suppressing the roll of the vehicle body.
JP 2002-218778 A JP 2002-211224 A JP 2006-82751 A

  The approaching / separating force generator included in the vehicle suspension system described in the above-mentioned patent document is controlled to suppress the roll of the vehicle body, for example, and plays a role in stabilizing the vehicle body posture. However, a system equipped with such an approaching / separating force generator is still under development, leaving much room for improvement. Therefore, it is considered that the practicality of the system is improved 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-mentioned problems, the vehicle suspension system of the present invention is a resistance force to the approaching / separating operation in the vertical direction between the suspension spring and the spring upper portion and the spring lower portion, and has a magnitude corresponding to the operation speed. A hydraulic-type absorber that generates an absorber force that is a force of a power source and an approaching / separating force generator that generates an approaching / separating force in a controllable manner are arranged in parallel to each other. Thus, it is configured to execute cooperative vibration damping control that generates an approaching / separating force corresponding to a difference between a damping force and an absorber force required to attenuate at least one of the vibrations. Incidentally, the approaching / separating force generator includes (a) an elastic body having one end connected to one of the spring upper part and the spring lower part, and (b) the other end of the elastic body, the spring upper part and the spring lower part. The other side and the elastic body are connected to each other, and the electromagnetic motor is a component of itself, and the force generated by the electromagnetic motor is applied to the elastic body based on the force generated by the electromagnetic motor. By changing the amount of deformation of the elastic body according to its own movement amount, and having an electromagnetic actuator that acts on the spring upper part and the spring lower part as an approaching and separating force via the elastic body, An elastic body has a shaft portion rotatably held by an 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 distal end portion coupled to the lower portion of the spring. Is fixed to the car body In both cases, the shaft portion is rotated around its axis by the force generated by itself, and the operation of the electromagnetic motor is reduced and the reduction ratio is reduced to 1/100 or less. The coordinated vibration damping control is performed based on the approaching / separating force to be generated by the approaching / separating force generating device, and the target rotational angle of the electromagnetic motor is determined. The actual rotation angle of the electromagnetic motor is set to the target rotation angle.

  In the vehicle suspension system of the present invention, when the vibration of at least one of the sprung portion and the unsprung portion is damped, an approach corresponding to the difference between the damping force and the absorber force required to dampen the vibration. The separating force is generated by the approaching / separating force generator. Therefore, according to the system of the present invention, it is possible to attenuate the vibration of at least one of the spring top and the spring bottom under the cooperation of the approaching / separating force generator and the absorber in consideration of the absorber force generated by the absorber. For example, it is possible to appropriately generate a damping force required to attenuate the vibration.

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 addition, in each of the following terms, (1) , (7), (8), and (10) are combined, and “Coordinated vibration damping control is performed. The limitation to “perform in this way” corresponds to claim 1 , claim (2) is claim 2, and the combination of claims (3) and (4) is claim 3. (6) corresponds to claim 4, and (9) corresponds to claim 5.

(1) a suspension spring disposed between the sprung portion and the unsprung portion;
A liquid that is arranged in parallel with the suspension spring and generates an absorber force that is a resistance force against the approaching / separating operation in the vertical direction between the spring upper part and the spring lower part and that has a magnitude corresponding to the operation speed. A pressure-type absorber,
A force that is arranged in parallel with the suspension spring and has an electromagnetic motor as a power source, and depends on the force generated by the electromagnetic motor, and moves the spring upper portion and the spring lower portion up and down in the vertical direction. An approaching / separating force generating device for generating an approaching / separating force,
A vehicle suspension system comprising: a control device that controls an approaching / separating force generated by the approaching / separating force generating device by controlling the electromagnetic motor;
The control device is a control for attenuating the vibration of at least one of the sprung portion and the unsprung portion by coordinating the approach / separation force generating device and the absorber, and is required for dampening the vibration. A vehicle suspension system that executes cooperative vibration damping control in which the approaching / separating force generating device generates an approaching / separating force corresponding to a difference between a damping force generated by the absorber and an absorber force generated by the absorber.

  In a vehicle suspension system in which a suspension spring, a hydraulic absorber, and the approaching / separating force generator are arranged in parallel between an upper part and an unsprung part, vibrations of at least one of the upper part and the lower part are vibrated. In the case of damping, the approaching / separating force generator can generate an approaching / separating force corresponding to the damping force required to attenuate the vibration. However, the hydraulic-type absorber generates an absorber force that is a resistance force against the approaching / separating operation in the vertical direction between the spring top and the spring bottom. From this, the force actually generated with respect to the vibration of at least one of the sprung portion and the unsprung portion is a damping force required to dampen the vibration (hereinafter sometimes referred to as “necessary damping force”). It gets bigger and smaller. More specifically, when the approach / separation force generator generates the approach / separation force as the required damping force, the direction in which the necessary damping force should be generated (hereinafter sometimes referred to as “necessary damping force direction”) and the absorber generate the absorber force. When the direction of generation (hereinafter sometimes referred to as “absorber force direction”) is the same, the absorber force promotes the required damping force, and against the vibration of at least one of the spring top and the spring bottom. The actual force generated is an excess of the force equivalent to the absorber force. On the other hand, if the required damping force direction and the absorber force direction are different, the absorber force interferes with the required damping force and corresponds to the absorber force. Power will be lacking.

  In view of the above, in the aspect of this section, when the vibration of at least one of the sprung portion and the unsprung portion is damped, the approaching / separating force corresponding to the difference between the required damping force and the absorber force is calculated as the approaching / separating force. Generated by the generator. Therefore, according to the aspect of this section, it is possible to attenuate the vibration of at least one of the sprung portion and the unsprung portion under the cooperation of the approaching / separating force generator and the absorber in consideration of the absorber force. It is possible to generate the necessary damping force with respect to the vibration without excess or deficiency.

  The “control for damping at least one vibration of the spring upper part and the spring unsprung” described in this section is, for example, a damping control based on at least one of a so-called skyhook damper theory and a ground hook damper theory, that is, a spring. The damping control may be based on at least one of the upper absolute speed and the unsprung absolute speed, or may be damping control based on the relative speed between the sprung portion and the unsprung portion.

  “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 configuration of the “suspension spring” is not particularly limited, and various types of structures such as a coil spring and an air spring can be widely used. Further, the “electromagnetic motor” provided as a power source in the approaching / separating force generator may be a rotary motor or a linear motor.

  (2) The cooperative vibration damping control is a control for damping the vibration of the upper part of the spring, and a magnitude of damping corresponding to the absolute speed on the spring as a damping force required for damping the vibration. The vehicle suspension system according to (1), wherein the approaching / separating force generating device generates a approaching / separating force corresponding to a difference between a force and an absorber force generated by the absorber.

  The cooperative vibration damping control described in this section is based on the so-called skyhook damper theory, and the required damping force is determined based on the sprung absolute speed. According to the aspect of this section, for example, it is possible to generate a damping force having a magnitude corresponding to the sprung absolute speed without excess or deficiency, and to appropriately execute control based on the skyhook damper theory. Become.

  (3) The vehicle suspension according to (2), wherein the absorber includes a damping coefficient changing mechanism that changes its damping coefficient that indicates its own ability to generate the absorber force and serves as a reference for the magnitude of the absorber force. system.

  The aspect described in this section is an aspect in which the structure of the absorber is limited. According to the aspect of this section, the absorber is generated according to the speed of the approaching / separating operation in the vertical direction between the spring upper part and the spring lower part. It is possible to change the degree of the magnitude of the absorber force. The “attenuation coefficient changing mechanism” described in this section may be changeable to any of a plurality of preset values, and any value within a preset range may be used. The value may be changeable.

  (4) The control device also controls the damping coefficient of the absorber by controlling the damping coefficient changing mechanism, and the damping coefficient is controlled by the upper part of the spring and the lower part of the spring while the upper part of the spring moves upward. , And when the sprung portion moves downward, the sprung portion and the unsprung portion are separated from each other. When the sprung portion moves upward, the sprung portion and the unsprung portion separate from each other. The vehicle suspension system according to the item (3), wherein the damping coefficient changing control is performed so that the damping coefficient is changed to be smaller than when the upper and lower parts of the spring approach each other while the upper part moves downward.

  When the coordinated vibration damping control is executed, if the required damping force direction and the absorber force direction are the same, the absorber force helps the necessary damping force, so the approaching / separating force generator is smaller than the necessary damping force. It is only necessary to generate the approaching / separating force, and the power consumption of the approaching / separating force generating device can be suppressed. On the other hand, if the required damping force direction and the absorber force direction are different, the absorber force interferes with the required damping force, so that the approaching / separating force generator needs to generate an approaching / separating force greater than the necessary damping force. The power consumption of the approaching / separating force generator may increase.

  In addition, the required damping force direction is determined by the movement direction of the spring top in the vertical direction, and the absorber force direction is determined by the approach / separation movement direction in the vertical direction of the spring top and the spring bottom. When the sprung portion approaches the sprung portion while the sprung portion moves upward, and when the sprung portion moves away from the sprung portion while the sprung portion moves downward, the necessary damping force direction and the absorber force direction On the other hand, if the sprung part moves upward while the sprung part is separated from the sprung part, and if the sprung part moves downward and the sprung part approaches the sprung part, the necessary damping is required. The force direction and the absorber force direction are the same.

  In view of the above, in the aspect of this section, when the required damping force direction and the absorber force direction are different, the absorber damping coefficient is reduced compared to the absorber damping coefficient when the directions are the same. Thus, the absorber power is reduced. According to the aspect of this section, when the required damping force direction and the absorber force direction are different, the absorber force that hinders the required damping force can be reduced, and the approaching / separating force can be reduced. It is possible to reduce power consumption by the force generator.

  (5) When the damping coefficient change control is performed, the damping coefficient of the absorber is set such that the upper part of the spring and the lower part of the spring are separated while the upper part of the spring moves upward, and the upper part and the spring of the upper part of the spring move downward. The vehicle suspension system according to item (4), wherein when the lower part approaches, the damping coefficient changing mechanism changes the damping coefficient to the smallest one among the damping coefficients that can be changed.

  The aspect of this term is an aspect which limits the damping coefficient of the absorber when the required damping force direction and the absorber force direction are different. When executing the cooperative vibration damping control, if the required damping force direction and the absorber force direction are different, the smaller the absorber force, the smaller the approaching / separating force, so according to the aspect of this section, for example, It becomes possible to realize the power saving of the system more effectively.

  (6) The control device can execute vehicle body posture control in which the approach / separation force generator generates the approach / separation force 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. The vehicle suspension system according to any one of (1) to (5).

  The mode of this section is a mode in which a limitation relating to another function of the approaching / separating force generator is added. If the approaching / separating force 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.

(7) 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 of the elastic body and the other of the sprung part and the unsprung part and connects the other and the elastic body, and the electromagnetic motor is a component of the electromagnetic body. By applying the force generated by itself to the elastic body depending on the generated force, the deformation amount of the elastic body is changed according to the amount of movement of the elastic body, and the force approaches the elastic body through the elastic body. The vehicle suspension system according to any one of (1) to (6), further comprising: an electromagnetic actuator that acts on the spring upper portion and the spring lower portion as a separation force.

  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. Therefore, 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 having various structures such as a coil spring and a torsion spring may be employed. it can.

(8) A shaft portion in which the elastic body is rotatably held by the upper portion of the spring, and an arm portion that extends from one end portion of the shaft portion so as to intersect the shaft portion and whose tip portion is connected to the lower portion of the spring. Have
The vehicle suspension system according to item (7), wherein the actuator is fixed to a vehicle body and rotates the shaft portion around an axis thereof by a force generated by itself.

  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 be twisted so that it has a function as a spring, and the arm portion may be bent so that it has a function as a spring. Note that the elastic body may be a member in which the shaft portion and the arm portion are separate members, and may be formed by integrating them.

(9) The ratio of the external input to the motor force required to operate 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 (7) or (8), 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. Therefore, if an actuator with a relatively small forward / reverse efficiency product is employed, for example, when restraining the roll, pitch, etc. of the vehicle body, the distance between the vehicle body and the wheel is maintained at a certain distance under the action of an external input. In some cases, the distance can be maintained with relatively little power. Therefore, according to the system of the aspect of this section, an excellent system can be realized in terms of power saving.

  (10) The actuator has a speed reducer that decelerates the operation of the electromagnetic motor, and the operation decelerated by the speed reducer becomes its own operation, and the reduction ratio of the speed reducer is 1/100 or less. The vehicle suspension system according to any one of (7) to (9).

  The aspect of this section is an aspect in which an actuator having a relatively large reduction ratio (meaning that the operation amount of the actuator is small relative to the operation amount of the electromagnetic motor) is employed. 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 electromagnetic motor can be reduced in size.

  (11) Items (1) to (10), wherein the absorber shows its own ability to generate the absorber force, and a damping coefficient serving as a reference for the magnitude of the absorber force is 1000 to 2000 N · sec / m. The vehicle suspension system according to any one of the above.

  The mode of this section is a mode in which the damping coefficient of the absorber is specifically limited. In the mode of this section, the damping coefficient of the absorber is set relatively low. There is a relationship between the damping coefficient of the absorber and the transmission characteristics of vibration from the unsprung part to the unsprung part. Generally speaking, the lower the damping coefficient of the absorber, the lower the transmission characteristic of vibrations in the high frequency range. Therefore, according to the aspect of this section, it is possible to suppress transmission of vibration in a relatively high frequency range from the unsprung portion to the unsprung portion, and for example, it is possible to improve the riding comfort of the vehicle. For example, when the approach / separation force generating device provided with the absorber is configured to change the approach / separation force by controlling the operation of the actuator, for example, from the problem of followability of the operation of the actuator, There is a tendency that it is difficult to cope with vibrations in a high frequency range, and this tendency is particularly strong when an actuator having a small forward / reverse efficiency product is employed. Therefore, in the system provided with the approaching / separating force generating device having such a structure, the absorber described in this section can cope with the vibration in the high frequency range, and thus the aspect of this section is a preferable aspect. It is. Also, for example, when the damping coefficient change control is executed, if the required damping force direction and the absorber force direction are different, reducing the damping coefficient of the absorber is effective for power saving of the system. In view of this, the embodiment of this section is advantageous.

  For example, when the “absorber” described in this section includes the above-described attenuation coefficient changing mechanism and can change the attenuation coefficient, the value is 1000 regardless of the value of the attenuation coefficient. It should just be in the range of -2000N.sec / m. Further, “1000 to 2000 N · sec / m” described in this section is not a value in the case where the absorber force is applied to the stroke operation of the absorber, but to the approach / separation operation between the vehicle body and the wheel. It is a value when it is assumed that the vehicle body and the wheel are directly operated in the vertical direction of the wheel.

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

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

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

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

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

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

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

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

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

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

  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. A cylindrical cushion rubber 119 is attached to the lower surface of the motor case 76. When the vehicle body and the wheel are relatively moved in a direction away from each other (hereinafter sometimes referred to as “rebound direction”), the annular member 116 comes into contact with the lower surface of the lid portion 66 of the housing 60 via the buffer rubber 118. On the contrary, when the vehicle body and the wheel are relatively moved in a direction in which the vehicle body and the wheel approach each other (hereinafter sometimes referred to as a “bound direction”), the upper surface of the lid 66 is below the lower surface of the motor case 76 via the buffer rubber 119. It comes to contact with. That is, the absorber 52 has a stopper against approach / separation between the vehicle body and the wheel, a so-called bound stopper, and a rebound stopper.

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

  The electromagnetic motor 140 includes a plurality of coils 148 fixed and arranged on one circumference along the inner surface of the peripheral wall of the housing 144, a hollow motor shaft 150 rotatably held by the housing 144, and the coil 148. And a permanent magnet 152 that is fixedly arranged on the outer periphery of the motor shaft 150. The electromagnetic motor 140 is a motor in which the coil 148 functions as a stator and the permanent magnet 152 functions as a rotor, and is a three-phase DC brushless motor. A motor rotation angle sensor 154 for detecting the rotation angle of the motor shaft 150, that is, the rotation angle of the electromagnetic motor 140 is provided in the housing 144. The motor rotation angle sensor 154 mainly includes an encoder, and is used for controlling the actuator 126, that is, controlling the 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 so on). The wave generator 156 includes an elliptical cam and a ball bearing fitted on the outer periphery thereof, and is fixed to one end of the motor shaft 150. The flexible gear 158 has a cup shape in which the peripheral wall portion can be elastically deformed, and a plurality of teeth (400 teeth in the speed reducer 142) are formed on the outer periphery on the opening side of the peripheral wall portion. The flexible gear 158 is connected to and supported by the shaft portion 130 of the L-shaped bar 122 described above. More specifically, the shaft portion 130 of the L-shaped bar 122 passes through the motor shaft 150, and the outer peripheral surface of the portion extending from the motor shaft 150 is relative to the bottom portion by spline fitting while penetrating the bottom portion of the flexible gear 158. It is connected non-rotatably. The ring gear 160 is generally ring-shaped and has a plurality of teeth (402 teeth in the present speed reducer 142) formed on the inner periphery, and is fixed to the housing 144. The flexible gear 158 has a peripheral wall portion fitted on the wave generator 156 and is elastically deformed into an elliptical shape, and meshes with the ring gear 160 at two locations located in the major axis direction of the ellipse and does not mesh at other locations. It is said that.

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

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

  The configuration of the suspension device 20 can be conceptually illustrated as shown in FIG. As can be seen from the drawing, the coil spring 50, the absorber 52, and the 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, as shown in FIG. 1, an adjustment device electronic control unit (adjustment device ECU) 170 that executes control for four adjustment devices 120 and an absorber electronic control unit that executes control for four absorbers 52 ( Absorber ECU) 172 is provided. A control device of the suspension system 10 is configured including these two ECUs 170 and 172.

  The 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 electromagnetic motor 140 included in each actuator 126, and a 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 electromagnetic motor 74 provided in the absorber 52. The absorber mainly includes a computer having four motor drive circuits 178 as a drive circuit and a CPU, ROM, RAM, and the like. And a controller 180 (see FIG. 12). Each of inverter 174 and each of motor drive circuits 178 are connected to battery 184 via converter 182, and each of inverters 174 is connected to electromagnetic motor 140 of corresponding adjustment device 120, and motor drive circuit 178 Each is connected to an electromagnetic motor 74 of the corresponding absorber 52.

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

  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 an actual lateral acceleration that is an acceleration, a longitudinal acceleration sensor 194 that detects a longitudinal acceleration generated in the vehicle body, a spring acceleration that is provided on a mount portion 54 of the vehicle body and detects a spring vertical acceleration A sensor 196 and a stroke sensor 198 for detecting the vehicle body wheel distance 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 also connected to each inverter 174, and controls the electromagnetic motor 140 of 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 longitudinal acceleration sensor 196 and the stroke sensor 198 are connected to the absorber controller 180. Furthermore, the absorber controller 180 is also connected to each motor drive circuit 178, and controls each absorber 52 by controlling them. Note that the ROM included in the computer of the absorber controller 180 stores a program related to the control of each absorber 52 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 are communicated as necessary.

≪Positive efficiency and reverse efficiency of the actuator of the adjusting 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 referred to simply as “reverse efficiency”) η _N is defined as the ratio of the minimum motor force at which the electromagnetic motor 140 cannot be rotated by some external input to the external input. The actuator positive efficiency (hereinafter, simply referred to as “positive efficiency”) η _P is the minimum motor force required to rotate the shaft portion 130 of the L-shaped bar 122 against a certain external input. Is defined as the ratio of its external input to. That is, if the actuator force (which may be considered as actuator torque) is Fa and the motor force (which may be considered as motor torque) generated by the electromagnetic motor 140 is Fm, then the positive efficiency η _P and the reverse efficiency η _N can be expressed as:
Positive efficiency η _P = Fa _P / Fm _P
Reverse efficiency η _N = Fm _N / Fa _N

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

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

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

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

≪Control of vehicle suspension system≫
i) Control of adjustment device a) Overview of roll suppression control and pitch suppression control In this system 10, the approach and separation force generated by each of the adjustment devices 120 including the actuator 126 is independently controlled, so that the roll of the vehicle body is controlled. Control (hereinafter also referred to as “roll suppression control”) and control of suppressing the pitch of the vehicle body (hereinafter also referred to as “pitch suppression control”) can be executed.

  In the system 10, when the vehicle turns, the approaching / separating force in the bound direction is adjusted by the adjusting device 120 on the inner side of the turning, and the approaching / separating force in the rebound direction is adjusted by the adjusting device 120 on the outer side of the turning, respectively. By generating the roll moment according to the magnitude of the roll moment, the roll of the vehicle body caused by the turning of the vehicle is suppressed. Further, during acceleration of the vehicle, the approaching / separating force in the bounce direction is adjusted by the adjusting device 120 on the front wheel side, and the approaching / separating force in the rebound direction is adjusted by the adjusting device 20 on the rear wheel side, respectively. By generating according to the size, squats of the vehicle body due to acceleration of the vehicle are suppressed. Further, when the vehicle is decelerated, the front wheel side adjusting device 120 provides the approaching / separating force in the rebound direction, and the rear wheel side adjusting device 120 provides the approaching / separating force in the bounce direction. By exhibiting it according to the size, the nose dive of the vehicle body caused by the deceleration of the vehicle is suppressed. 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.

b) Outline of cooperative vibration damping control When damping the vibration of the vehicle body, it is desirable to execute damping control based on the so-called skyhook damper theory. More specifically, the damping force required for damping the sprung vibration (hereinafter sometimes referred to as “necessary damping force”), that is, a damping force having a magnitude corresponding to the absolute sprung speed is applied to the sprung. It is desirable to generate against vibration. The hydraulic-type absorber 52 can exclusively generate an absorber force against sprung vibration. However, since the absorber force is a resistance force against the relative movement between the spring top and the spring bottom, the direction in which the absorber force is generated (hereinafter sometimes referred to as “absorber force direction”) and the magnitude of the absorber force It cannot be changed arbitrarily. For this reason, it is difficult to generate the absorber force as the necessary damping force.

  On the other hand, since the adjusting device 120 can generate an approaching / separating force having an arbitrary magnitude in an arbitrary direction, it is conceivable to generate the approaching / separating force as a necessary damping force. However, since the absorber force affects the sprung vibration as described above, the force actually generated with respect to the sprung vibration is larger or smaller than the necessary damping force. Specifically, if the direction in which the required damping force should be generated (hereinafter sometimes referred to as “necessary damping force direction”) and the absorber force direction are the same, the absorber force will promote the necessary damping force, The force actually generated with respect to the sprung vibration is an extra force equivalent to the absorber force. On the other hand, if the required damping force direction is different from the absorber force direction, the absorber force hinders the required damping force. The power corresponding to the absorber power is insufficient.

  In view of the above, in the present system 10, in consideration of the absorber force generated by the absorber 52, the adjustment device 120 and the absorber 52 are coordinated to dampen the vibration of the sprung portion (hereinafter referred to as “ In some cases, “cooperative vibration damping control” is executed. More specifically, the adjusting device 120 generates an approaching / separating force corresponding to the difference between the required damping force and the absorber force. That is, in the system 10, the sprung vibration is attenuated by the absorber force and the approaching / separating force.

In the present system 10, as described above, the adjusting device 120 is configured to vibrate in a relatively high frequency range because the actuator 126 having a relatively small forward / reverse efficiency product η _P · η _N is employed. It has become difficult to deal with. Therefore, the absorber 52 provided in the present system 10 is an absorber suitable for vibration attenuation in the high frequency range, and the action of the absorber 52 suppresses transmission of vibration in a relatively high frequency range to the vehicle body. Become. In other words, in the present system 10, vibrations in a relatively low frequency range in which the operation of the actuator 126 can sufficiently follow, that is, a low frequency range including the sprung resonance frequency, are dealt with by the adjusting device 120 and the absorber 52, and the spring The absorber 52 deals with vibrations in a high frequency range including the lower resonance frequency. Therefore, the attenuation coefficient of the absorber 52 is set to a low value to ensure the above function. Specifically, the first damping coefficient C ₁ is 2000 N · sec / m, and the second damping coefficient C ₂ is 1000 N · sec / m (value assumed to directly act on the wheel for the operation of the wheel). It is set to less than half of 3000 to 5000 N · sec / m, which is a value set for a shock absorber in a suspension system that does not have the adjusting device 120, that is, a conventional shock absorber.

c) Details of Comprehensive Control of Coordinate Vibration Attenuation Control, Roll Suppression Control, and Pitch Suppression Control In the present system 10, control in which the above three controls are integrated is executed. In this overall control, the motor rotation angle of the electromagnetic motor 140 is controlled in each adjusting device 120 to exert an appropriate approaching / separating force based on the sprung absolute speed, the roll moment received by the vehicle body, the pitch moment, and the like. Yes. Specifically, the target motor rotation angle, which is the target motor rotation angle, is determined based on the sprung absolute speed, the roll moment received by the vehicle body, the pitch moment, and the like, and the actual motor rotation angle is determined as the target motor rotation angle. Thus, the electromagnetic motor 140 is controlled. Incidentally, the direction and magnitude of the approaching / separating force has a corresponding relationship with the direction and magnitude of the motor force to be generated, that is, the power supplied to the electromagnetic motor 140. In actual control of the electromagnetic motor 140, the power supplied is appropriate. It is executed to become a thing. The electromagnetic motor 140 functions as a generator and may generate electric power, and the generated electric power also affects the motor force. Therefore, strictly speaking, the power supplied to the electromagnetic motor 140 means the power supplied to the coil 148 of the electromagnetic motor 140.

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 cooperative vibration damping control, roll suppression control, and pitch suppression control. The components for each control are
Coordinated vibration damping target motor rotation angle component (vibration damping component) θ ^* _S
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.

The vibration damping component θ ^* _S is determined by a necessary damping force that is a damping force determined based on the sprung absolute velocity and an absorber force generated by the absorber 52. Specifically, based on the sprung absolute velocity Vu, the required damping force F _H is determined according to the following equation:
F _H = Vu · C _S (C _S : damping coefficient based on skyhook theory)
Based on the approaching / separating operation speed between the sprung part and the unsprung part, that is, the relative speed Vs between the sprung part and the unsprung part, the absorber force F _A is determined according to the following equation.
F _A = Vs · C _A (C _A : damping coefficient of absorber)
Then, in order to generate an approaching / separating force corresponding to the difference between the required damping force F _H and the absorber force F _A , the vibration damping component θ ^* _S is determined according to the following equation.
θ ^* _S = K _S · (F _H −F _A ) (K _S : gain)

The roll suppression component θ ^* _R is determined based on the lateral acceleration that indicates the roll moment received by the vehicle body. More specifically, the control is a lateral acceleration used for the control based on 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. The lateral acceleration Gy ^* is determined according to the following equation:
Gy ^* = K _A · Gyc + K _B · Gyr (K _A , K _B : gain)
Based on the determined control lateral acceleration Gy ^* , the roll suppression component θ ^* _R is determined. In the adjustment device controller 176 of the adjustment device ECU 170, map data of the roll suppression component θ ^* _R having the control lateral acceleration Gy ^* as a parameter is stored, and when the roll suppression component θ ^* _R is determined, the map data Is referenced.

The pitch suppression rotation angle component θ ^* _P is determined based on the longitudinal acceleration that indicates the pitch moment received by the vehicle body. More specifically, the pitch suppression rotation angle component θ ^* _P is determined according to the following equation based on the actually measured actual longitudinal acceleration Gzg.
θ ^* _P = K _C · Gzg (K _C : Gain)

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

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

Here, given the previous actuator efficiency, generally speaking, the integral term current component i _S, since may be a current component for maintaining the motor rotation angle theta, the size of the motor according to the negative efficiency eta _N Any current component that generates force can be used. Therefore, the integral gain K _I that is the gain of the second term in the above equation for determining the target supply current i ^* is set so that the integral term component i _S has a value that is in line with the inverse efficiency characteristic. For example, when considering the roll suppression when the vehicle performs a typical one-turn operation, as shown in FIG. 9, the roll suppression force to be generated by the adjusting device 20, that is, the approaching / separating force changes, and the electromagnetic force 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], the actuator 126 must be operated against an external input. Therefore, a current that is large enough to generate a motor force that exceeds the motor force according to the positive efficiency characteristic is generated by the electromagnetic motor 140. Need to be supplied. In view of this, the proportional gain K _P is set to a value that can generate a motor force according to the positive efficiency characteristic in a state where the motor rotation angle deviation Δθ does not become so large.

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

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

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

ii) Control of the absorber In the system 10, as described above, vibration damping control based on the so-called skyhook damper theory is performed using the approaching / separating force generated by the adjusting device 120 and the absorber force generated by the absorber 52. In this control, the adjusting device 120 generates an approaching / separating force corresponding to the difference between the necessary damping force and the absorber force. For this reason, when the necessary damping force direction and the absorber force direction are the same, the absorber force helps the necessary damping force. Therefore, the adjusting device 120 may generate an approaching / separating force smaller than the necessary damping force, The power consumption of the adjustment device 120 can be suppressed. On the other hand, if the required damping force direction and the absorber force direction are different, the absorber force hinders the required damping force, so the adjusting device 120 needs to generate an approaching / separating force larger than the required damping force. The power consumption of the device 120 may increase.

  In view of the above, in the present system 10, when the cooperative vibration damping control is executed, if the required damping force direction and the absorber force direction are different, the required damping force direction and the absorber force direction are the same. In comparison, damping coefficient changing control is executed to change the damping coefficient of the absorber 52 to be small in order to reduce the absorber force.

  Specifically, the absorber force direction is the bounce direction when the sprung portion and the unsprung portion are separated from each other, and the rebound direction when the sprung portion and the unsprung portion are approached. . On the other hand, the necessary damping force direction is the bound direction when the sprung portion moves upward, and the rebound direction when the sprung portion moves downward. In the present system 10, when the sprung portion moves upward, the sprung absolute velocity Vu is +, and when the sprung portion moves downward, the sprung absolute velocity Vu is-. When the sprung portion and the unsprung portion are separated from each other, the relative speed Vs between the sprung portion and the unsprung portion is +, and when the sprung portion and the unsprung portion approach each other, the relative speed Vs is −.

  From the above, when the required damping force direction and the absorber force direction are both bound directions, the sprung absolute speed Vu is + and the relative speed Vs is +, and the spring top moves while the spring top moves upward. And the unsprung part are separated from each other. When the necessary damping force direction and the absorber force direction are both in the rebound direction, the sprung absolute velocity Vu is-and the relative velocity Vs is-, and the sprung portion and the unsprung portion move while the sprung portion moves downward. And approach. Therefore, when the sprung portion is separated from the sprung portion while the sprung portion is moving upward, and when the sprung portion and the sprung portion are approached while the sprung portion is moved downward, the necessary damping force direction and the absorber The force direction is the same, and the sign of the sprung absolute speed Vu and the sign of the relative speed Vs are the same. On the other hand, when the required damping force direction is the bounce direction and the absorber force direction is the rebound direction, the sprung absolute speed Vu is + and the relative speed Vs is −, and the sprung part moves upward while the sprung part moves upward. The unsprung part approaches. When the required damping force direction is the rebound direction and the absorber force direction is the bounce direction, the sprung absolute speed Vu is-and the relative speed Vs is +, and the spring top moves downward while the spring top moves. The unsprung part is separated. Therefore, when the sprung portion moves away from the sprung portion and the sprung portion moves apart, and when the sprung portion moves upward and the sprung portion approaches the sprung portion, the necessary damping force direction and the absorber The force direction is different, and the sign of the sprung absolute speed Vu is different from the sign of the relative speed Vs.

Therefore, in the present system 10, when cooperative vibration damping control is executed, when the sprung portion moves upward while the sprung portion is separated from the sprung portion, and when the sprung portion moves downward, the sprung portion If the spring and the lower approaches, that is, when the code of the code and the relative velocity Vs of the absolute sprung speed Vu is the same, the damping coefficient C _a of the absorber 52 and the first damping coefficient C _1, sprung Is moved downward and the sprung portion is separated from the unsprung portion, and when the sprung portion is moved upward and the sprung portion and the unsprung portion are approached, that is, the sign of the sprung absolute velocity Vu and the relative velocity. When the sign of Vs is different, the attenuation coefficient C _A of the absorber 52 is set to a second attenuation coefficient C ₂ that is smaller than the first attenuation coefficient C ₁ .

≪Control program≫
In the present system 10, 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. 10. On the other hand, 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. 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 adjustment device control program is executed for each actuator 126 of the four adjustment devices 120, and the absorber control program is executed for each of the four absorbers 52. In the following description, control processing for one actuator 126 and control processing for one absorber 52 will be described in consideration of simplification of description.

i) Adjustment device control program In the process according to this program, first, in step 1 (hereinafter simply referred to as “S1”. The same applies to the other steps), based on the control lateral acceleration described above, the roll suppression control is performed. The roll suppression component θ ^* _R for the pitch suppression control is determined, and subsequently, in S2, the pitch suppression component θ ^* _P for pitch suppression control is determined based on the longitudinal acceleration.

  Next, in S3, the sprung vertical acceleration Gu is detected based on the sprung vertical acceleration sensor 196, and in S4, the sprung absolute speed Vu is calculated based on the sprung vertical acceleration Gu. Subsequently, in S5, the vehicle body wheel distance X is detected based on the stroke sensor 198. In S6, the relative speed Vs between the sprung portion and the unsprung portion is calculated based on the vehicle wheel distance X.

Next, in S7, the absorber force F _A is determined according to the relative speed Vs. Information regarding the damping coefficient C _A of the absorber 52 used when determining the absorber force F _A is acquired from the absorber controller 180 as necessary by the adjusting device controller 176. Subsequently, in S8, the required damping force F _H is determined according to the sprung absolute velocity Vu, and in S9, the vibration damping component θ ^* _S is determined based on the absorber force F _A and the required damping force F _H. Is done. In S10, the target motor rotation angle θ ^* is determined by adding the vibration damping component θ ^* _S , the roll suppression component θ ^* _R, and the pitch suppression component θ ^* _P. Subsequently, in S11, based on the target motor rotation angle θ ^* , the target supply current i ^* is determined according to the formula according to the above-described PI control law. In S12, the control signal based on the determined target supply current i ^* is an inverter. After being transmitted to 174, one execution of the program ends.

ii) Absorber control program In the processing according to this program, first, the vertical acceleration Gu of the sprung portion is detected based on the vertical acceleration sensor 196 in S21, and the sprung absolute velocity Vu is determined based on the vertical acceleration Gu in S22. Calculated. Subsequently, in S23, the vehicle body wheel distance X is detected based on the stroke sensor 198. In S24, the relative speed Vs between the sprung portion and the unsprung portion is calculated based on the vehicle wheel distance X.

Next, in S25, it is determined whether the required damping force direction is different from the absorber force direction. Specifically, it is determined whether or not the sign of the relative speed Vs is different from the sign of the sprung absolute speed Vu. When the sign of the respective speeds are different from determination in S26, the damping coefficient C _A of the absorber 52 is a second damping coefficient C _2. Also, if the sign of the respective speeds is determined to the same, in S27, the damping coefficient C _A of the absorber 52 is set to the first damping coefficient C _1. Then, in S28, the control signal based on the determined attenuation coefficient C _A is then sent to the motor drive circuit 178, one execution of the present program is terminated.

≪Functional structure of controller≫
The adjustment device controller 176 that executes the adjustment device control program can be considered to have a functional configuration as shown in FIG. 12 in view of its execution processing. As can be seen from the figure, the adjustment device controller 176 determines the vehicle body posture control component as a functional unit that executes the processes of S1 and S2, that is, a functional unit that determines the roll suppression component θ ^* _R and the pitch suppression component θ ^* _P. The unit 210 is a functional unit that executes the processes of S3 to S9, that is, a functional unit that determines the vibration damping component θ ^* _S , and the vibration damping component determination unit 212 is a functional unit that executes the processes of S10 to S12. As a functional unit for executing roll suppression control and pitch suppression control, the vehicle body posture control execution unit 214 is used as a functional unit for executing the processes of S10 to S12, that is, as a functional unit for executing cooperative vibration damping control. Each has a control execution unit 216. The vibration damping component determination unit 212 executes the process of S8 on the function unit that determines the absorber force F _A generated by the absorber 52, that is, the absorber force determination unit 218, as the function unit that executes the process of S7. As the functional unit, a functional unit that determines the necessary damping force F _H required to attenuate the vibration of the sprung portion, that is, a necessary damping force determining unit 220 is provided.

Also, the absorber controller 180 that executes the above-described absorber control program can be considered to have a functional configuration as shown in FIG. 12 in view of the execution process. As can be seen, the absorber controller 180, a functional portion to execute the processing in S25 to S27, that is, based on the required damping force direction and the absorber force direction, as a functional unit for determining a damping coefficient C _A of the absorber 52 The attenuation coefficient determination unit 222 is included.

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 flowchart which shows an adjustment apparatus control program. It is a flowchart which shows an absorber control program. It is a block diagram which shows the function of the control apparatus which manages control of a suspension system.

Explanation of symbols

  10: Vehicle suspension system 36: Second lower arm (lower spring) 50: Coil spring (suspension spring) 52: Absorber 54: Mount part (upper spring) 74: Electromagnetic 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: Electromagnetic motor 142: Reducer 170: Adjustment device electronic control unit (adjustment device) 172: Absorber electronic control unit (adjustment device)

Claims (5)

A suspension spring disposed between the spring top and the spring bottom;
A liquid that is arranged in parallel with the suspension spring and generates an absorber force that is a resistance force against the approaching / separating operation in the vertical direction between the spring upper part and the spring lower part and that has a magnitude corresponding to the operation speed. A pressure-type absorber,
A force that is arranged in parallel with the suspension spring and has an electromagnetic motor as a power source, and depends on the force generated by the electromagnetic motor, and moves the spring upper portion and the spring lower portion up and down in the vertical direction. An approaching / separating force generating device for generating an approaching / separating force,
A vehicle suspension system comprising: a control device that controls an approaching / separating force generated by the approaching / separating force generating device by controlling the electromagnetic motor;
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 of the elastic body and the other of the sprung part and the unsprung part and connects the other and the elastic body, and the electromagnetic motor is a component of the electromagnetic body. By applying the force generated by itself to the elastic body depending on the generated force, the deformation amount of the elastic body is changed according to the amount of movement of the elastic body, and the force approaches the elastic body through the elastic body. An electromagnetic actuator that acts on the upper and lower springs as a separation force;
Have
The elastic body has a shaft portion rotatably held on the spring upper portion, 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 spring lower portion,
The actuator is fixed to the vehicle body and rotates the shaft portion around its axis by a force generated by itself, and decelerates the operation of the electromagnetic motor and has a reduction ratio of 1/100 or less. It has a structure that has a reduction gear that has been decelerated and the operation that is decelerated by the reduction gear becomes its own operation,
The control device is
Control for attenuating the vibration of at least one of the sprung portion and the unsprung portion by coordinating the approaching / separating force generating device and the absorber, the damping force required to damp the vibration, and the Coordinated vibration damping control in which the approaching / separating force generating device generates an approaching / separating force corresponding to a difference from the absorber force generated by the absorber is performed ,
In the coordinated vibration damping control, the target rotation angle of the electromagnetic motor is determined based on the approaching / separating force to be generated by the approaching / separating force generating device, and the actual rotation angle of the electromagnetic motor becomes the target rotation angle. A suspension system for a vehicle characterized by   The cooperative vibration damping control is a control for damping the vibration of the upper part of the spring, and the damping force having a magnitude corresponding to the absolute speed on the spring as the damping force required for damping the vibration, and the The vehicle suspension system according to claim 1, wherein the approach / separation force generating device generates the approach / separation force corresponding to the difference from the absorber force generated by the absorber. The absorber includes a damping coefficient changing mechanism that changes its damping coefficient that indicates its own ability to generate the absorber force and serves as a reference for the magnitude of the absorber force,
The control device controls the damping coefficient of the absorber by controlling the damping coefficient changing mechanism, and the upper part of the spring approaches the lower part of the spring while the upper part of the spring moves upward. When the upper part of the spring is moved downward, the upper part of the spring is separated from the lower part of the spring. When the upper part of the spring is moved upward, the upper part of the spring is separated from the lower part of the spring. The suspension system for a vehicle according to claim 2, wherein damping coefficient change control is performed so as to be smaller than when the spring upper portion and the spring lower portion approach each other while moving to the left. The control device can execute vehicle body posture control in which the approaching / separating force generating device generates the approaching / separating force 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. The vehicle suspension system according to any one of claims 1 to 3. The ratio of the external input to the motor force required to operate 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 actuator also operated by the external input. In the case where the ratio of the motor force required for not being able to be made to the external input is defined as the reverse efficiency of the actuator, the product of the positive efficiency and the reverse efficiency, and the forward / reverse efficiency product, respectively,
The vehicle suspension system according to any one of claims 1 to 4, wherein the actuator has a structure having a forward / reverse efficiency product of 1/2 or less .

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