JP2008162333A - Vehicular suspension system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance practicality of a suspension system provided with an electromagnetic shock absorber for generating resistance force and propulsion force relative to relative movement of a sprung part and an unsprung part. <P>SOLUTION: The force of the absorber includes the force for attenuating vibration of the sprung part and the force for attenuating vibration of the unsprung part, the forces can be separately controlled, and control gains Cs, Cg set corresponding to the respective forces are changed in the determination of the respective forces. Thereby, the control state of the absorber can be changed among the plurality of specific control states S<SB>1</SB>, S<SB>2</SB>, S<SB>3</SB>in which the control gains Cs, Cg are set to specific values. Accordingly, the circumstance that the vehicle is placed at present is determined from various aspects, and the control state capable of generating the absorber force capable of suitably responding to the circumstance that the vehicle is placed at present can be easily realized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a suspension system including an electromagnetic shock absorber that generates a resistance force and a propulsion force against relative movement between an upper spring portion and an unspring portion.

In recent years, as a suspension system for vehicles, an electromagnetic shock absorber (hereinafter simply referred to as “absorber”) that generates a resistance force and a propulsive force against the relative movement of the upper and lower springs depending on the force of an electromagnetic motor. A so-called electromagnetic suspension system including a certain type) has been studied. For example, there is a suspension system described in the following patent document. This electromagnetic suspension system is expected as a high-performance suspension system because of its advantages such as easily realizing suspension characteristics based on the so-called skyhook theory.
Japanese Patent Laid-Open No. 2003-102425

  In the electromagnetic suspension system described in the above patent document, for the purpose of reducing power consumption, when the vehicle speed is equal to or higher than a set value, the damping force is reduced according to the difference between the vehicle speed and the set value. Yes. In addition, when it is estimated that the change in the posture of the vehicle body is relatively large even if the vehicle speed is equal to or higher than the set value, the amount of reduction in the damping force generated in the absorber is reduced or not reduced. ing. However, in the system described in the above-mentioned patent document, the damping force generated in the absorber is determined based on the speed of the relative motion (stroke motion) between the sprung portion and the unsprung portion, and their relative displacement, and the damping force. This change is made only for the purpose of reducing power consumption, and is executed only depending on limited conditions such as vehicle speed and body posture change. In terms of practicality of the electromagnetic suspension system, It ’s never enough. The electromagnetic absorber can be obtained by making any of the criteria for determining the damping force, the purpose of changing the damping force, the dependency status, etc. different from those described in the above-mentioned patent document, or by adding another one. It is thought that the practicality of the suspension system equipped with This invention is made | formed in view of such a situation, and makes it a subject to improve the practicality of the suspension system provided with the electromagnetic type absorber.

  In order to solve the above problems, a vehicle suspension system according to the present invention is configured to be able to generate a force including an on-spring speed-dependent component and an unsprung-speed-dependent component in an electromagnetic absorber. By changing the control gain set corresponding to each of the upper-speed-dependent component and the unsprung-speed-dependent component, the control gain of the absorber is set to a specific value. It is characterized by changing between a plurality of specific control states.

  In the suspension system of the present invention, the damping force of the absorber includes a force for damping the vibration of the upper part of the spring and a force for damping the vibration of the lower part of the spring, and these can be controlled separately. Yes. And on that assumption, the damping force can be changed by changing the control state of the absorber between a plurality of specific control states. Therefore, the vehicle suspension system of the present invention is a highly practical system because it is possible to realize a control state that can appropriately cope with the situation where the vehicle is currently placed.

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 some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. In the following paragraphs, each of items (1) to (14) corresponds to each of claims 1 to 14.

(1) a suspension spring disposed between the upper and lower spring parts;
An electromagnetic shock absorber that is arranged in parallel with the suspension spring and has an electromagnetic motor and generates resistance and propulsive force against the relative movement of the upper and lower springs depending on the force of the electromagnetic motor;
The spring force that is generated by the shock absorber is determined based on the sprung speed and the sprung speed corresponding gain that is the control gain corresponding to the sprung speed. A control device that controls the shock absorber so as to have a force including an unsprung speed dependent component that is determined based on a unsprung speed corresponding gain that is a control gain corresponding to the unsprung speed. A suspension system,
The control device is
By changing the sprung speed corresponding gain and the unsprung speed corresponding gain, the control state of the shock absorber is changed to a plurality of specific values in which the sprung speed corresponding gain and the unsprung speed corresponding gain are set to specific values. A vehicle suspension system comprising a control state changing unit that changes between control states.

  In the aspect described in this section, it is possible to execute control that combines both control based on the so-called skyhook damper theory and control based on the pseudo groundhook theory on an electromagnetic absorber. The control state can be changed between a plurality of specific control states. In this mode, the absorber force for attenuating the vibration of the sprung portion and the absorber force for attenuating the vibration of the unsprung portion can be controlled separately, so that various vibrations can be appropriately dealt with. is there. In addition, the aspect of this section is configured to change the control state of the absorber on the premise of that, for example, since the degree of freedom in setting the specific control state can be increased, Variations can be enriched. As a result, it is possible to easily realize a control state that can determine the situation where the vehicle is currently placed from various viewpoints and generate an absorber force that can appropriately cope with the situation where the vehicle is currently placed. It can be done.

  In the aspect of this section, “the control state is changed between a plurality of specific control states” specifically means that the control state is referred to as a sprung speed speed gain (hereinafter simply referred to as “sprung gain”). Specific control state is 2 in the case where it is defined as a point on the coordinate plane defined by the coordinate axis for the unsprung speed corresponding gain (hereinafter, simply referred to as “unsprung gain”). If two or more specific control states are set, the control state is changed on a line connecting the points representing each of the two control states. This means that the control state is changed in a region surrounded by a line connecting points representing each of the states. The “specific control state” referred to in this section is not particularly limited. For example, various control states determined with emphasis on some performance in the vehicle can be widely adopted according to the purpose of changing the damping force. is there.

  As the “suspension spring” in this aspect, various springs such as a coil spring and a fluid spring such as an air spring can be employed. The “electromagnetic shock absorber” in the aspect of this section is not limited in its specific structure, and is not particularly limited in function. For example, in addition to the function of damping the vibration generated in the vehicle, the function of controlling the posture of the vehicle body is exhibited for the purpose of suppressing the roll, pitch, etc. of the vehicle body caused by turning, acceleration and deceleration of the vehicle. May be. The type of the “electromagnetic motor” that is the power source of the actuator is not particularly limited, and various types of motors such as a DC brushless motor can be adopted. Alternatively, a linear motor may be used. In addition, the suspension system according to the aspect of the present aspect may be provided with a “drive circuit” for driving a motor and having a structure for controlling the absorber by controlling the operation of the drive circuit. As the drive circuit, for example, a so-called inverter can be employed. For example, the inverter may have a structure in which a motor is driven by the operation of a switching element, and it is desirable to employ a structure capable of performing PWM (Pulse Width Modulation) control.

  (2) At least one of the plurality of specific control states is (a) a ride comfort-oriented state determined with an emphasis on good ride comfort of the vehicle, and (b) good wheel grounding performance. (C) an overall performance emphasis state determined by emphasizing the overall performance of the vehicle including the ride comfort of the vehicle and the ground contact performance of the wheels; Paragraph (1) selected from a power generation amount emphasis state determined with emphasis on an increase in the amount of power generated by the electromagnetic motor and (e) a power generation dedicated state in which the electromagnetic motor is exclusively in a power generation state. The vehicle suspension system described in 1.

  The mode described in this section is a mode in which the specific control state is specifically limited. The “riding comfort emphasis state” referred to in this section can be considered as a control state in which the transmission characteristic of unsprung vibration to the upper part of the spring is relatively low, for example. More specifically, it is assumed that vibration near the sprung resonance frequency, that is, vibration transmission in a relatively low frequency range (for example, about 0.5 to 2 Hz) is sufficiently suppressed. It is desirable to have a control state that can sufficiently suppress vibration transmission in a frequency range intermediate to the resonance frequency (for example, about 5 Hz to 7 Hz). In view of this, for example, it is desirable that the control state is such that the sprung gain is set to a relatively large value and the unsprung gain is set to a relatively small value. Further, the “ground contact priority state” can be considered as a control state in which the ground load variation, which is the load variation from the static load of the wheel, is small, for example. Specifically, for example, it is desirable to sufficiently suppress vibration near the unsprung resonance frequency, that is, vibration of the lower part of the spring in a relatively high frequency range (for example, about 8 Hz to 12 Hz). Even in this grounding-oriented state, it is desirable to sufficiently suppress vibration transmission in at least the sprung resonance frequency region in order to make the riding comfort of the vehicle as good as possible. From this point of view, it is desirable that the grounding-oriented state is a control state in which both the sprung gain and the unsprung gain are set to relatively large values. The “total performance emphasis state” can be considered, for example, as a control state in which the balance between the ride comfort and the ground contact property of the vehicle described above is relatively good. It can be considered as an intermediate control state.

  On the other hand, the “power generation priority state” can be considered as a control state in which, for example, the relative motion between the sprung portion and the unsprung portion can be increased, and specifically, for example, the sprung gain and the unsprung gain. It is desirable that the control state is set to a relatively small value. The “power generation-only state” is, for example, a damping coefficient (in a so-called short-circuit braking state) exhibited by the absorber when the sprung gain and the unsprung gain have the same value and the energization terminals of the electromagnetic motor are short-circuited. It can be considered that the control state is set so as to obtain a smaller attenuation coefficient. In other words, the power generation exclusive state is based on the premise that a resistance force corresponding to the speed of relative movement between the upper and lower springs is generated, and does not become a braking state in which electric power is supplied from the power source to the electromagnetic motor (so-called reverse braking state). It can be considered that the control state is set as follows. In order to increase the amount of power generated by the electromagnetic motor as much as possible, the sprung gain and unsprung gain are set to values that can obtain an attenuation coefficient that is 1/2 the attenuation coefficient at the time of the short circuit. It is desirable that

  By the way, since the above-mentioned riding comfort-oriented state, grounding-oriented state, and overall performance-oriented state are all effective control states for suppressing some vibrations, they are defined as their superordinate concepts. It can be considered as one aspect of the “damping control state”. On the contrary, since the power generation priority state and the power generation dedicated state are control states with low power consumption or no power consumption, they are an aspect of “power saving control state” defined as a superordinate concept thereof. Can be considered. In consideration of power saving of the system, it is desirable that the drive circuit and the power source described above have a structure capable of regenerating the power generated by the electromagnetic motor. In the case of a system configured to regenerate the generated power of the motor, if the control state of the absorber is set to the above-mentioned power generation amount-oriented state or the power generation dedicated state, the regenerated power will also increase, further reducing the power consumption of the system. Will contribute.

  (3) The control state changing unit is based on one or more indicators relating to any of a state of a road surface on which the vehicle travels, a state of vibration generated in the vehicle, and a charging state of a power source connected to the electromagnetic motor. The vehicle suspension system according to (1) or (2), wherein the control state of the shock absorber is changed.

  The mode described in this section is a mode in which the index for changing the control state of the shock absorber is specifically limited. The “road surface condition on which the vehicle travels” referred to in this section means that the road is a wavy road, a gravel road, etc., or the roughness of the road surface. The frequency height, amplitude magnitude, etc. can be used. “The state of vibration generated in the vehicle” means the degree of intensity of vibration generated in the vehicle. For example, the acceleration and speed of the sprung part and the unsprung part, the relative speed between the sprung part and the unsprung part, the sprung vibration, the unsprung vibration, the amplitude of the relative vibration, the ground load fluctuation, etc. can be adopted. . Incidentally, the degree of the intensity of vibration generated on the wheels not only means the state of vibration but also means the state of the road surface because it can estimate the roughness of the road surface. In other words, the unsprung acceleration, velocity, amplitude, ground load fluctuation, etc., as indicators for the degree of vibration intensity generated on the wheels should be considered as indicators for both road conditions and vibration conditions. Is possible. As an index relating to “the state of charge of the power source”, for example, a charge amount, a residual electric energy amount, a ratio of the remaining energy amount based on the charge capacity, and the like can be adopted. These indices are suitable as indices indicating the situation where the vehicle is currently placed.

  Note that the control state of the absorber may be changed based on the above-described index value, and the control state of the absorber may be changed based on the index value within a set time traced back from the current time. As the value of the indicator within the set time retroactive from the present time, the value obtained by a known method such as the degree of change of the indicator value can be adopted, and specifically, the setting retroactive from the present time. It is possible to adopt the maximum value, average value, effective value (RMS value, square root of the mean value of squares), etc. of the index value within the time.

  (4) The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain to the sprung speed corresponding gain and the unsprung speed corresponding gain set for each of the plurality of specific control states. The vehicle suspension system according to item (3), wherein the control state of the shock absorber is changed by determining the weight based on the one or more indices based on the value.

  The mode described in this section is a mode in which the method for determining the sprung gain and the unsprung gain is limited. In the mode of this section, the weight is changed according to the value of the index. And the unsprung gain is changed, and the control state of the absorber is changed. According to the aspect of this section, it is possible to easily change the sprung gain and the unsprung gain continuously. The mode of this section may be a mode in which the sprung gain and the unsprung gain are linearly changed by the weighting, or a mode in which the sprung gain and the unsprung gain are changed nonlinearly as will be described in detail later. Good. In addition, when three or more specific control states are set and a plurality of the indicators are set, it is possible to adopt a mode in which the sprung gain and the unsprung gain are determined by a plurality of weights according to the number It is.

  (5) The control state changing unit may change a control state of the shock absorber to a road surface state where the vehicle travels, a vibration state generated in the vehicle, or a charging state of a power source connected to the electromagnetic motor. The vehicle suspension according to (1) or (2), wherein the vehicle suspension is changed between a first specific control state and a second specific control state, each of which is the specific control state, based on an index relating to system.

  (6) The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain for each of the first specific control state and the second specific control state. The vehicle suspension system according to item (5), wherein the control state of the shock absorber is changed by determining the weight and the unsprung speed corresponding gain value by weighting based on the index.

  The modes described in the above two items are modes limited to those in which two specific control states are set. In these modes, as an index for changing the control state, an appropriate one of the above-mentioned indexes regarding the road surface state, the vibration state, and the power supply state is adopted according to the two specific control states. That's fine.

  (7) The control state changing unit performs weighting according to a rule such that the sprung speed corresponding gain and the unsprung speed corresponding gain determined with respect to the change of the index change nonlinearly. The vehicle suspension system according to item (6), which determines an upper speed corresponding gain and an unsprung speed corresponding gain.

  The mode described in this section is a mode in which the gradient of the change of the sprung gain and the unsprung gain with respect to the change of the index is changed according to the value of the index. According to the aspect of this section, a system with a high degree of freedom is realized regarding the setting for changing the control state of the shock absorber based on the index.

  (8) The weighting follows a rule such that as the index value increases, the gradient of the change in the sprung speed corresponding gain and the unsprung speed corresponding gain with respect to the change in the index increases or decreases. The vehicle suspension system according to item (7).

  In the mode described in this section, each of the sprung gain and the unsprung gain is on the coordinate plane defined by the coordinate axis for the sprung gain and the coordinate axis for the index value, and the coordinate axis and the index value for the unsprung gain. A mode in which the sprung gain and the unsprung gain are changed on a line that is convex upward or convex downward on the coordinate plane when indicated on each of the coordinate planes defined by the coordinate axes. It is. According to the aspect of this section, when the index value changes within the range in which the gradient of the change is increased, the control state is changed relatively large.

  (9) The value of the index increases according to a rule that the gradient increases as the value of the index increases in one of a situation where the value of the index increases and a condition where the value of the index decreases. The vehicle suspension system according to item (8), wherein the vehicle has a rule that the gradient decreases as the value of the index increases in the other of the situation of decreasing and the condition of decreasing.

  In the aspect described in this section, when considered on the coordinate plane described above, each of the sprung gain and the unsprung gain is changed on a line that protrudes upward when the index value increases and decreases downward when it decreases. Or an aspect that is convex on a line that protrudes downward when the index value increases and that protrudes upward when the index value decreases. In other words, the aspect of this section is an aspect in which a hysteresis characteristic is added to the relationship between the index value and the sprung gain and unsprung gain. In the aspect of this section, for example, whether the index value is increasing or decreasing may be determined based on a change in the index value within a set time traced back from the present time.

(10) The first specific control state is set to a ride comfort-oriented state determined with emphasis on good ride comfort of the vehicle, and the second specific control state is excellent in wheel grounding. It is assumed that the grounding property is emphasized, with a focus on being,
The control state changing unit changes the control state of the shock absorber based on an index relating to any one of a state of a road surface on which the vehicle travels as an index and a state of vibration generated in the vehicle. 5. The vehicle suspension system according to any one of items 5) to (9).

  The aspect described in this section is an aspect in which two specific control states and an index for changing the control state are limited to specific ones. As mentioned earlier, keeping the ride comfort of the vehicle as good as possible and keeping the wheel grounding as good as possible are contradictory in actual control. According to the aspect of the present invention, the control state can be changed between the riding comfort-oriented state and the grounding-oriented state according to the road surface state and the vibration state, so according to the situation where the vehicle is placed, An appropriate control state can be realized.

  When driving on roads with poor road conditions, such as roads with rough roads, or when vibrations are generated in the vehicle, grounding is required to ensure the handling and stability of the vehicle. It is desirable to execute control with an emphasis on performance. In consideration of that, the aspect described in this section is, for example, that the shock absorber control state is set to a ride comfort-oriented state as the road surface is bad or the vibration generated in the vehicle is large. It is possible to adopt a mode of changing so as to approach the grounding-oriented state. In addition, about the change, you may employ | adopt the aspect of changing the control gain mentioned previously nonlinearly. Specifically, the weighting follows a rule such that the slope of the change in the sprung gain and unsprung gain with respect to the change becomes smaller as the road surface condition is worse or the vibration generated in the vehicle is larger. It is possible to adopt the mode described above. According to this aspect, when the road surface condition is deteriorated even slightly, or when a certain amount of vibration is generated in the vehicle, the control state is greatly shifted from the ride-oriented state to the ground-oriented state, and the vehicle Can be more effectively secured.

(11) The first specific control state is focused on (a) a ride comfort-oriented state determined with an emphasis on good ride comfort of the vehicle, and (b) an excellent wheel grounding property. And (c) an overall performance emphasis state determined with emphasis on the overall performance of the vehicle including the ride comfort of the vehicle and the ground contact performance of the vehicle. The second specific control state is (d) a power generation amount priority state determined with an emphasis on an increase in the power generation amount of the electromagnetic motor, and (e) a power generation dedicated state where the electromagnetic motor is exclusively in a power generation state. One of the states and
The control state changing unit changes the control state of the shock absorber based on an indicator relating to a charging state of a power source connected to the electromagnetic motor as the indicator (5) to (9). The vehicle suspension system according to any one of the above.

  The aspect described in this section is an aspect in which two specific control states and an index for changing the control state are limited to specific ones. As explained above, (a) riding comfort-oriented state, (b) grounding-oriented state, (c) total performance-oriented state is a vibration suppression control state, and (d) power generation amount-oriented state, ( e) The power generation dedicated state is a power saving control state. Therefore, the mode of this section is a mode of changing the control state between the vibration suppression control state and the power saving control state. The vibration suppression control state and the power saving control state are, for example, conflicting control states for the purpose, but according to the aspect of this section, appropriate control between the conflicting control states is performed according to the state of charge of the power source. It is possible to realize the state.

  More specifically, when the state of charge of the power supply is low, it is desirable that the second specific control state, which is the power saving control state, is set. It is desirable to adopt a mode in which the control state of the shock absorber is changed so as to approach the vibration-saving control state from the power saving control state. In addition, it is also possible to combine this aspect with the aspect which changes the control gain mentioned above nonlinearly. Specifically, for example, it is possible to adopt a mode in which the weighting follows a rule such that the higher the state of charge, the greater the slope of the change in the sprung gain and the unsprung gain with respect to the change. . In this aspect, when the charging state is low even when it is high, the control state is greatly shifted from the vibration suppression control state to the power saving control state, and the charging state is becoming high in the low state Even so, the control state is shifted little by little from the power saving control state to the vibration suppression control state side. It is also possible to change the weighting rule between a situation where the state of charge is getting higher and a situation where the state of charge is getting lower. For example, in a situation where the weighting is increasing in the state of charge, the rule is such that the change gradient becomes smaller as the state of charge becomes higher, and in the situation where the state of charge is becoming lower, the lower the state of charge, the lower the state of charge. It is possible to adopt a mode that follows a rule that the change gradient becomes small. According to this aspect, when the charging state is decreasing in the high state, the control state is greatly shifted to the power saving control state side, and conversely, when the charging state is increasing in the low state, The control state is greatly shifted to the vibration suppression control state side.

  (12) The control state changing unit may change a control state of the shock absorber to a road surface state where the vehicle travels, a vibration state generated in the vehicle, or a charging state of a power source connected to the electromagnetic motor. (1) or (2) that changes between the first specific control state, the second specific control state, and the third specific control state, which are the specific control states, respectively, based on the two indices relating to The suspension system for a vehicle according to item).

  (13) The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain for each of the first specific control state and the second specific control state. The value of the sprung speed corresponding gain and the unsprung speed corresponding gain determined by the first weighting based on one of the two indices with respect to the value of the gain and the unsprung speed corresponding gain, and the third specific control state The control state of the shock absorber is changed by determining by the second weighting based on the other of the two indices with respect to the sprung speed corresponding gain and the unsprung speed corresponding gain set for The vehicle suspension system according to item (12).

  The modes described in the above two sections are modes limited to those in which three specific control states are set. According to the mode of this section, the range of control state changes is wide and the vehicle is placed. More appropriate absorber force can be generated according to various situations. In the latter mode, it is possible to combine the above-described modes in which the control gain is changed nonlinearly.

(14) One of the first specific control state and the second specific control state is a ride comfort-oriented state determined with emphasis on good ride comfort of the vehicle, and the other is a wheel grounding property. The third specific control state emphasizes that the amount of power generated by the electromagnetic motor is large, and is focused on the amount of power generated. A state dedicated to power generation in which the electromagnetic motor is exclusively in a power generation state,
The control state changing unit includes the first weighting based on an index relating to any one of a state of a road surface on which the vehicle travels as one of the two indices and a state of vibration occurring in the vehicle, and the two indices. The vehicle suspension according to item (13), wherein the control state of the shock absorber is changed by the second weighting based on an indicator relating to a charging state of a power source connected to the electromagnetic motor as the other of system.

  The aspect described in this section is an aspect in which three specific control states and two indexes for changing the control state between them are limited to specific ones, and the above-mentioned items (10) and (11) The embodiment described in the item) is combined. That is, the aspect of this section has the technical features of the aspects of the items (10) and (11), and the effects obtained by these aspects can be obtained. Also in the aspect of this section, it is possible to combine the aforementioned aspects in which the control gain is changed nonlinearly.

  Several embodiments of the claimable invention will now be described in detail with reference to the drawings. In addition to the following examples, the claimable invention is implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Aspect of the Invention] section. can do.

(A) First Example << Configuration of Suspension System >>
FIG. 1 schematically shows a vehicle suspension system 10 according to a first embodiment of the claimable invention. The suspension system 10 includes four independent suspension type suspension devices corresponding to the front, rear, left and right wheels 12, each of which is a spring absorber in which a suspension spring and a shock absorber are integrated. Assy20. The wheel 12 and the spring absorber assembly 20 are generic names, and when it is necessary to clarify which of the four wheels corresponds, as shown in FIG. In some cases, FL, FR, RL, and RR are attached to the front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  As shown in FIG. 2, the spring absorber assembly 20 is provided between a suspension lower arm 22 that holds the wheel 12 and forms a part of the lower part of the spring, and a mount part 24 that is provided on the vehicle body and forms a part of the upper part of the spring. The actuator 26 is an electromagnetic absorber disposed so as to connect them, and an air spring 28 as a suspension spring provided in parallel therewith.

  The actuator 26 includes an outer tube 30 and an inner tube 32 that fits into the outer tube 30 and protrudes upward from the upper end portion of the outer tube 30. The outer tube 30 is connected to the lower arm 22 via a mounting member 34 provided at the lower end portion thereof, while the inner tube 32 is connected to the mount portion 24 at a flange portion 36 formed at the upper end portion thereof. ing. The outer tube 30 is provided with a pair of guide grooves 38 on the inner wall surface thereof so as to extend in the direction in which the axis of the actuator 26 extends (hereinafter sometimes referred to as “axial direction”). Each of a pair of keys 40 attached to the lower end of the inner tube 32 is fitted into each of the outer tube 30 and the inner tube 32 by the guide groove 38 and the key 40. Relative rotation is impossible and relative movement is possible in the axial direction. Incidentally, a seal 42 is attached to the upper end portion of the outer tube 30 to prevent air leakage from the pressure chamber 44 described later.

  The actuator 26 includes a screw rod 50 as a male screw portion in which a thread groove is formed, and a nut 52 as a female screw portion that holds the bearing ball and is screwed with the screw rod 50. A mechanism and an electromagnetic motor 54 as a power source (hereinafter sometimes simply referred to as “motor 54”) are provided. The motor 54 is fixedly accommodated in the motor case 56, and the flange portion of the motor case 56 is fixed to the upper surface side of the mount portion 24, and the flange portion 36 of the inner tube 32 is attached to the flange portion of the motor case 56. By being fixed, the inner tube 32 is connected to the mount portion 24 via the motor case 56. A motor shaft 58 that is a rotation shaft of the motor 54 is integrally connected to the upper end portion of the screw rod 50. That is, the screw rod 50 is disposed in the inner tube 32 with the motor shaft 58 extended, and is rotated by the motor 54. On the other hand, the nut 52 is fixedly supported on the upper end portion of the nut support cylinder 60 attached to the inner bottom portion of the outer tube 30 in a state of being screwed with the screw rod 50.

  The air spring 28 includes a housing 70 fixed to the mount portion 24, an air piston 72 fixed to the outer tube 30 of the actuator 26, and a diaphragm 74 connecting them. The housing 70 has a generally cylindrical shape with a lid, and is fixed to the lower surface side of the mount portion 24 on the upper surface side of the lid portion 76 in a state where the inner tube 32 of the actuator 26 is passed through a hole formed in the lid portion 76. Yes. The air piston 72 has a generally cylindrical shape, and is fixed to the upper portion of the outer tube 30 with the outer tube 30 fitted therein. The housing 70 and the air piston 72 are connected by a diaphragm 74 while maintaining airtightness, and the pressure chamber 44 is formed by the housing 70, the air piston 72, and the diaphragm 74. The pressure chamber 44 is filled with compressed air as a fluid. With such a structure, the air spring 28 elastically supports the lower arm 22 and the mount portion 24, that is, the wheel 12 and the vehicle body, by the pressure of the compressed air.

  From the structure as described above, when the spring upper part and the spring lower part approach and separate from each other, the outer tube 30 and the inner tube 32 can be relatively moved in the axial direction. Along with the relative movement, the screw rod 50 and the nut 52 relatively move in the axial direction, and the screw rod 50 rotates with respect to the nut 52. The motor 54 is capable of applying a rotational torque to the screw rod 50, and generates a resistance force that prevents the stroke operation against the relative operation (stroke operation) between the spring upper part and the spring lower part. Is possible. The actuator 26 functions as a so-called absorber (also referred to as a “damper”) by causing this resistance force to act as a damping force for the stroke motion between the sprung portion and the unsprung portion. In other words, the actuator 26 has a function of applying a damping force to the stroke operation by an actuator force that is an axial force generated by the actuator 26 itself. The actuator 26 also has a function of causing the actuator force to act as a driving force, that is, a driving force for the stroke operation. With this function, it is possible to execute control based on the Skyhook damper theory in which a damping force proportional to the sprung absolute velocity is applied. Further, the actuator 26 positively changes the distance between the upper part and the lower part in the vertical direction (hereinafter sometimes referred to as “the distance between the unsprung springs”) by the actuator force. It also has a function of maintaining the distance at a predetermined distance. With this function, it is possible to effectively suppress the roll of the vehicle body at the time of turning, the pitch of the vehicle body at the time of acceleration / deceleration, and the adjustment of the vehicle height of the vehicle.

  The suspension system 10 is a fluid inflow / outflow device for inflowing / outflowing air (air) as a fluid to / from an air spring 28 of each spring / absorber assembly 20, more specifically, a pressure chamber 44 of the air spring 28. An air supply / discharge device 80 is connected to supply air to the pressure chamber 44 and discharge air from the pressure chamber 44. Although detailed description is omitted, the suspension system 10 can adjust the amount of air in the pressure chamber 44 of each air spring 28 by the air supply / discharge device 80. The spring length of the air spring 28 can be changed to change the distance between the sprung springs for each wheel 12. Specifically, it is possible to increase the amount of air in the pressure chamber 44 to increase the unsprung distance, and decrease the amount of air to decrease the unsprung distance.

  In the present suspension system 10, the suspension electronic control unit (ECU) 140 operates the spring absorber assembly 20, that is, controls the actuator 26 and the air spring 28. Specifically, the operation of the motor 54 of the actuator 26 and the operation of the air supply / discharge device 80 are controlled. The ECU 140 is a controller 142 composed mainly of a computer having a CPU, ROM, RAM, etc., a driver 144 as a drive circuit of the air supply / discharge device 80, and a drive circuit corresponding to the motor 54 of each actuator 26. Inverter 146. The driver 144 and the inverter 146 are connected to the battery 150 via the converter 148, and each control valve, pump motor, and the like of the air supply / discharge device 80 and the motor 54 of each actuator 26 are connected to the converter 148. Power is supplied from a power source including the battery 150 and the battery 150. Since the motor 54 is driven at a constant voltage, the amount of power supplied to the motor 54 is changed by changing the amount of supplied current.

  The vehicle includes an ignition switch [I / G] 160, a vehicle speed sensor [v] 162 for detecting the vehicle traveling speed (hereinafter sometimes referred to as “vehicle speed”), and the unsprung distance between the wheels 12. Four stroke sensors [St] 164 for detecting the distance, a vehicle height change switch [HSw] 166 operated by the driver for the vehicle height change instruction, an operation angle sensor [δ for detecting the operation angle of the steering wheel 170, longitudinal acceleration sensor [Gx] 172 that detects actual longitudinal acceleration that is the longitudinal acceleration actually generated in the vehicle body, and lateral acceleration sensor [Gy] 174 that detects actual lateral acceleration that is the lateral acceleration actually generated in the vehicle body , Four on-spring vertical acceleration sensors [Gzs] 176 for detecting the vertical acceleration (vertical acceleration) of each mount portion 24 of the vehicle body corresponding to each wheel 12, Four unsprung vertical acceleration sensors [Gzg] 178 for detecting the longitudinal acceleration of the wheel 12, a throttle sensor [Sr] 180 for detecting the throttle throttle opening, and a brake pressure sensor [Br] 182 for detecting the master cylinder pressure of the brake , A charge amount sensor [E] 184 for detecting the charge amount of the battery 150 as an index relating to the state of charge of the power source is provided, and these are connected to the controller 142. The ECU 140 controls the operation of the spring absorber assembly 20 based on signals from these switches and sensors. Incidentally, the character [] is a symbol used when the above-mentioned switch, sensor, etc. are shown in the drawing. The ROM of the computer of the controller 142 stores a program related to the control of the actuator 26 described later, various data, and the like.

≪Inverter configuration≫
As shown in FIG. 3, the motor 54 of each actuator 26 is a three-phase brushless DC motor in which coils are star-connected (Y-connected), and is controlled and driven by the inverter 146 as described above. The inverter 146 is a general one as shown in the figure, corresponds to each of the high side (high potential side) and the low side (low potential side), and the U phase which is the three phases of the motor 54. Six switching elements HUS, HVS, HWS, LUS, LVS, and LWS corresponding to each of the V, W, and W phases. In addition, the switching element controller 190 included in the inverter 146 includes a resolver [θ] 192 that is provided in the motor 54 and detects the rotation angle of the motor 54, and an actual amount that actually flows through the motor 54 in the inverter 146. An energizing current sensor [I] 194 for measuring the amount of energizing current is connected. The switching element controller 190 determines the motor rotation angle (electrical angle) by the resolver 192 and opens and closes the switching element based on the motor rotation angle. The inverter 146 drives the motor 54 by so-called sine wave drive, and the amount of current flowing in each of the three phases of the motor 54 changes in a sine wave shape, and the phase difference differs by 120 ° in electrical angle. Thus, the inverter 146 is controlled. The inverter 146 is configured to energize the motor 54 by PWM (Pulse Width Modulation) control. By changing the ratio (duty ratio) between the pulse-on time and the pulse-off time, the amount of current flowing through the motor 54 ( The magnitude of the rotational torque generated by the motor 54 is changed by changing the energization current amount. Specifically, increasing the duty ratio increases the energizing current amount and increases the rotational torque generated by the motor 54. Conversely, decreasing the duty ratio decreases the energizing current amount. The rotational torque generated by the motor 54 is reduced.

  The direction of the rotational torque generated by the motor 54 may be the same as the direction in which the motor 54 is actually rotating, or vice versa. When the direction of the rotational torque generated by the motor 54 and the rotational direction of the motor 54 are reversed, that is, when the actuator 26 is acting as a resistance force against the stroke operation, the force generated by the motor 54 Does not necessarily depend on the power (current) supplied from the power source. More specifically, when the motor 54 is rotated by an external force, the motor 54 is in a power generation state, and the motor 54 generates a motor force depending on the electromotive force generated at that time, that is, the actuator 26. May generate an actuator force depending on the electromotive force.

  When the actuator 26 generates an actuator force that depends on the electromotive force, the inverter 146 has a structure that can regenerate the power generated by the electromotive force to the power source. Further, when the rotational torque generated by the motor 54 and the rotational direction of the motor 54 are reversed, the PWM control of the switching element described above controls the amount of current flowing through each coil of the motor 54 by electromotive force. Thus, the magnitude of the rotational torque generated by the motor 54 is changed by changing the duty ratio. That is, the inverter 146 controls the current flowing through the coil of the motor 54, that is, the energization current of the motor 54, regardless of whether the current is supplied from the power supply or the generated current caused by the electromotive force. It is structured to control the motor force.

≪Basic control of suspension system≫
In the present suspension system 10, each of the four spring absorber assemblies 20 can be controlled independently. In each of the spring absorber assemblies 20, the actuator force of the actuator 26 is independently controlled to control the vibration of the vehicle body and the wheel 12, that is, the control for damping the sprung vibration and the unsprung vibration (hereinafter referred to as “vibration damping”). May be referred to as “control”). In addition, control for suppressing the roll of the vehicle body caused by turning of the vehicle (hereinafter sometimes referred to as “roll suppression control”), control for suppressing the pitch of the vehicle body caused by acceleration / deceleration of the vehicle (hereinafter referred to as “roll control”). (Sometimes referred to as “pitch suppression control”). In the vibration damping control, roll suppression control, and pitch suppression control, the target actuator force is determined by adding the vibration damping component, roll suppression component, and pitch suppression component, which are components of the actuator force for each control. It is executed comprehensively by being controlled to generate the target actuator force. In the following description, the actuator force and its component are positive values corresponding to the force in the direction (rebound direction) separating the spring top and the spring bottom, and the direction in which the spring top and the spring bottom are brought closer. It is assumed that the one corresponding to the force in the (bound direction) is a negative value.

  In the suspension system 10, a control for changing the vehicle height based on the driver's intention (hereinafter referred to as “vehicle height change”) for the purpose of coping with traveling on a road with large road undulations by the air spring 28. Is also executed). The vehicle height change control will be briefly described. The vehicle height change control is executed when a target set vehicle height that is a set vehicle height to be realized by an operation of the vehicle height change switch 166 based on the driver's intention is changed. A sprung unsprung distance as a target for each wheel 12 is set in accordance with each of the target set vehicle heights, and a sprung spring for each wheel 12 is set based on a detection value of the stroke sensor 164. The operation of the air supply / discharge device 80 is controlled so that the lower distance becomes the target distance, and the distance between the unsprung springs of each wheel 12 is changed to a distance corresponding to the target set vehicle height. Further, in this vehicle height change control, so-called auto leveling control is also performed for the purpose of dealing with changes in vehicle height due to, for example, changes in the number of passengers and changes in the load capacity of luggage.

i) Vibration damping control In the vibration damping control, a vibration damping component F _V of the actuator force is determined so as to generate an actuator force having a magnitude corresponding to the vibration speed in order to attenuate the vibration of the vehicle body and the wheel 12. . That is, the control is based on both the control based on the so-called skyhook damper theory and the control based on the pseudo groundhook theory. Specifically, the vertical movement speed of the vehicle body mount portion 24 calculated from the spring vertical acceleration detected by the spring vertical acceleration sensor 176 provided on the vehicle mount portion 24, the so-called sprung speed Vs. And the vertical movement speed of the wheel 12 calculated from the unsprung longitudinal acceleration detected by the unsprung longitudinal acceleration sensor 178 provided in the lower arm 22, so-called unsprung speed Vg, according to the following equation: A vibration damping component F _V is calculated.
F _V = Cs · Vs−Cg · Vg
Here, Cs is a sprung speed corresponding gain that is a control gain for generating a damping force corresponding to the vertical operating speed of the mount 24 of the vehicle body, and Cg is the vertical operating speed of the wheel 12. This is a gain corresponding to unsprung speed, which is a control gain for generating a damping force according to. The suspension system 10 is configured to change the unsprung gain Cs and unsprung gain Cg depending on the situation, as will be described in detail later.

ii) Roll suppression control When the vehicle turns, the roll moment resulting from the turn separates the upper spring part and the lower spring part on the inner side of the turn, and closes the upper spring part and the lower part of the spring on the outer side of the turn. It is done. In the roll suppression control, in order to suppress the separation on the turning inner ring side and the approach on the turning outer ring side, the actuator force in the bounce direction is applied to the actuator 26 on the turning inner ring side, and the actuator force in the rebound direction is applied to the actuator 26 on the turning outer ring side. Each is generated as a roll restraining force. Specifically, first, as a lateral acceleration indicating the roll moment received by the vehicle body, an estimated lateral acceleration Gyc estimated based on the steering angle δ of the steering wheel and the vehicle speed v, and a lateral acceleration sensor 174 were measured. Based on the actual lateral acceleration Gyr, a control lateral acceleration Gy ^* , which is a lateral acceleration used for control, is determined according to the following equation.
Gy ^* = K ₁ · Gyc + K ₂ · Gyr (K ₁ , K ₂ : gain)
Such based on the determined control-use lateral acceleration Gy ^*, the roll restraining force component F _R is determined according to the following equation.
F _R = K ₃ · Gy ^* (K ₃ : Gain)

iii) Pitch suppression control For the nose dive of the vehicle body that occurs during deceleration, such as during braking of the vehicle body, the upper spring portion and the lower spring portion on the front wheel side are brought close to each other by the pitch moment that generates the nose dive, and the rear The upper spring portion and the lower spring portion are separated from each other. In addition, for the squat of the vehicle body generated during acceleration of the vehicle body, the front wheel side spring upper part and the spring lower part are separated by the pitch moment that generates the squat, and the rear wheel side spring upper part and the lower spring part are separated from each other. Is approached. In the pitch suppression control, the actuator force is generated as the pitch suppression force in order to suppress the approach / separation distance in those cases. Specifically, as longitudinal acceleration indicative of the pitch moment acting on the vehicle body, is employed the actual longitudinal acceleration Gx that is actually measured by the longitudinal acceleration sensor 172, and based on the actual longitudinal acceleration Gx, the pitch restraining force component F _P is the following Determined according to the formula.
F _P = K ₄ · Gx (K ₄ : Gain)
It should be noted that the pitch suppression control is executed when the throttle opening detected by the throttle sensor 180 or the master cylinder pressure detected by the brake pressure sensor 182 exceeds a set threshold.

iv) Target Actuator Force and Motor Operation Control The actuator 26 is controlled based on a target actuator force that is an actuator force that should be generated. In detail, as described above, the vibration damping component F _V of the actuator force, a roll restrain component F _R, the pitch restrain component F _P is determined on the basis of their, the actuator force as a target in accordance with the following equation F ^* Is determined.
F ^* = F _V + F _R + F _P
Then, based on the target actuator force F ^* determined as described above, a target duty ratio is determined, and a command based on the duty ratio is transmitted to the inverter 146. Inverter 146 drives motor 54 to generate a target actuator force under the appropriate duty ratio.

≪Change of control state in vibration damping control≫
As described above, the suspension system 10 is configured to change the sprung gain Cs and the unsprung gain Cg according to the situation, thereby changing the control state in the vibration damping control of the actuator 26. Have been to. In the vibration damping control of this system, three specific control states that are control states in which the sprung gain Cs and the unsprung gain Cg are set to specific values are determined. The control state is changed by. FIG. 4 is a diagram in which the control state is defined as a point on the coordinate plane with the sprung gain Cs and the unsprung gain Cg as coordinate axes. In the following description, the control state is represented as S = (Cs, Cg).

Of the specific control states, the first specific control state is a ride comfort-oriented state S ₁ = (Cs ₁ , Cg ₁ ) determined with emphasis on good ride comfort of the vehicle. In other words, this state of emphasis on ride comfort suppresses the transmission of both the vibration in the sprung resonance frequency range and the vibration in the intermediate frequency range between the unsprung resonance frequency range to the upper part of the spring. As shown in FIG. 4, the sprung gain Cs ₁ is set to a relatively large value and the unsprung gain Cg ₁ is set to a relatively small value. In addition, the second specific control state is a grounding priority state S ₂ = (Cs ₂ , Cg ₂ ) determined with emphasis on good wheel grounding. This grounding-oriented state is a control state for the purpose of suppressing the unsprung vibration in the unsprung resonance frequency region while suppressing the transmission of the vibration in the sprung resonance frequency region from the unsprung portion to the sprung portion. As can be seen from FIG. 4, both the sprung gain Cs ₂ and the unsprung gain Cg ₂ are set to relatively large values. Further, in the third specific control state, the power generation amount priority state S ₃ = (Cs) determined with emphasis on the fact that the power generation amount of the motor 54 increases, that is, the power amount regenerated in the battery 150 increases. ₃ and Cg ₃ ). This power generation amount emphasis state is a control state for the purpose of increasing the relative movement between the sprung portion and the unsprung portion, and as shown in FIG. 4, both the sprung gain Cs ₃ and the unsprung gain Cg _3. Is set to a relatively small value.

  In the present system 10, the control state is changed in a region surrounded by a line connecting points representing each of the three specific control states. More specifically, based on an indicator regarding the road surface on which the vehicle is traveling, an indicator relating to the state of vibration occurring in the vehicle, and an indicator relating to the state of charge of the battery 150, the situation where the vehicle is currently placed is determined. The control state is changed according to the determination.

More specifically, in the present system 10, first, the values of sprung gain and unsprung gain in the control state between the first specific control state and the second specific control state, that is, S ₁ and S ₂ are calculated. point S _1-2 of the line connecting the, by the first weighting factor α with respect to their respective on the value located on the gain and the unsprung gain spring specific control state is determined according to the following equation.
S _1-2 = (1-α) · S ₁ + α · S ₂
As an index for determining the first weighting coefficient α, a ground load variation f that is a load variation from a static load of the wheel is adopted, and an effective value f _RMS ( The RMS value, the square root of the mean value of the squares) is calculated, and the first weighting coefficient α is determined based on the effective value f _RMS of the ground load variation. The ground load fluctuation represents the degree of vibrations occurring on the wheels, and it is also possible to estimate the roughness of the road surface. It is treated as an index for both vibration states. Incidentally, the ground load variation f is calculated according to the following equation based on the sprung acceleration Gzs and unsprung acceleration Gzg detected by the two longitudinal acceleration sensors 176 and 178.
_{f = M U · Gzs + M} L · Gzg
Here, M _U and M _L are the sprung weight and the unsprung weight, respectively. Note that a ground load variation in a specific frequency range (for example, unsprung resonance frequency range) may be calculated by filtering or the like, and the first weighting coefficient α may be determined based on the ground load variation in the specific frequency range. .

FIG. 5 is a diagram showing the relationship between the effective value f _RMS of the ground load variation and the first weighting coefficient α. For example, when the road surface is rough and the degree of vibration input to the wheels is severe, the effective value f _RMS of the ground load variation increases. In such a case, it is desirable that the grounding property is good in order to ensure the maneuverability and stability of the vehicle. In view of this, in the present system 10, as shown in FIG. 5, as the effective value f _RMS of the ground load variation increases, the first weighting coefficient α is set to a value closer to 1 so that the control state S _1-2 will be in a state close to the grounding-oriented state from the riding-oriented state. Further, the first weighting coefficient α is changed nonlinearly with respect to the effective value f _RMS of the ground load variation, specifically, on an upwardly convex curve. For this reason, when the road surface on which the vehicle starts to run or when the vehicle starts to vibrate, that is, when the ground load fluctuation starts to increase, the control state changes from a ride comfort-oriented state to a ground-contact-oriented state. The vehicle is greatly shifted to the side, and the maneuverability and stability of the vehicle are sufficiently secured.

Next, the values of the sprung gain and the unsprung gain in the control state between the control state _S1-2 and the third specific control state, that is, the control state S ^{* that} is the control target for changing the control state, are as follows. The second weighting coefficient β for the sprung gain and the unsprung gain set for each of the control states S _1-2 and S ₃ is determined according to the following equation.
S ^* = (1-β) · S ₃ + β · S _1-2
The second weighting coefficient β is determined based on an index related to the state of charge of the battery 150. Specifically, as the index, the charge amount E of the battery 150 detected by the charge amount sensor 184 is adopted, and an average value of the charge amount within a set time retroactive from the present time is calculated, and based on the value A second weighting factor β is determined.

FIG. 6 is a diagram illustrating a relationship between the average value E of the charge amount and the second weighting coefficient β. When the amount of charge of the power source is small, it is desirable that the amount of power regenerated by the battery 150 is large. Therefore, in the present system 10, the second weighting coefficient β is set to a value closer to 0 as the amount of charge E decreases. Thus, the control state S ^* is brought to a control state closer to the power generation amount priority state than the ride comfort priority state and the ground contact priority state. Further, the second weighting coefficient β is changed nonlinearly with respect to the charge amount E, specifically, on a downwardly convex curve. Therefore, in a situation where the charge amount E is decreasing, even if the charge amount E is high, the control state is shifted to the power generation amount important state side, and the energy consumption of the actuator 26 is effectively suppressed. is there.

Since the target control state S ^* is determined as described above, the control state S ^* is an appropriate control state in consideration of the road surface state, the vibration state, and the state of charge of the battery 150. That is, in the present system 10, the value of the sprung gain and the unsprung gain in the target control state S ^* is determined based on the first weighting α based on the indicators relating to the road surface state and the vibration state, and the indicator relating to the state of charge of the battery 150. Is determined according to the following equation, whereby the control state S ^* in the vibration damping control of the actuator 26 is set to an appropriate control state according to the situation where the vehicle is currently placed. It is.
S ^* = (1−β) · S ₃ + β · {(1−α) · S ₁ + α · S ₂ }
= (1-α) · β · S ₁ + α · β · S ₂ + (1-β) · S ₃

≪Actuator control flow≫
The actuator 26 as described above is controlled by the actuator control program shown in the flowchart of FIG. 7 at a short time interval (for example, several milliseconds to several tens of milliseconds) while the ignition switch 160 is in the ON state. It is performed by being repeatedly executed by 142. The control flow will be briefly described below with reference to the flowchart shown in the figure. The actuator control program is executed for each actuator 26 of the spring absorber assembly 20 provided on each of the four wheels 12. In the following description, processing by this program for one actuator 26 will be described in consideration of simplification of description.

In this program, first, in step 1 (hereinafter abbreviated as “S1”, other steps are also the same), the sprung acceleration Gzs and the unsprung acceleration Gzg detected by the two longitudinal acceleration sensors 176 and 178 are calculated. Based on this, the effective value f _RMS of the ground load variation is calculated. In subsequent S2, the first weighting coefficient α is determined in accordance with the ground load fluctuation effective value f _RMS . More specifically, the ROM of the suspension ECU 140 stores map data of the first weighting coefficient α using the contact load fluctuation effective value f _RMS shown in FIG. 5 as a parameter. A weighting factor α is determined. In S3, the average value of the charge amount E of the battery 150 within the set time is calculated from the detection result by the charge amount sensor 184. In S4, the second weighting coefficient β based on the average value of the charge amount E is It is determined with reference to the map data shown in FIG. In S5, a target control state S ^* as an appropriate control state is determined according to the following equation based on these two weighting coefficients α and β. That is, the sprung gain Cs and the unsprung gain Cg in the target control state S ^* are determined according to the following equations.
S ^* = (1−α) · β · S ₁ + α · β · S ₂ + (1−β) · S ₃

Next, in S6, the vibration damping component F _V is determined based on the sprung gain Cs and the unsprung gain Cg determined as described above. Furthermore, in S7 to S9, in the manner previously described, the roll restrain component F _R, and the pitch restrain component F _P is determined by summing those three components, the target actuator force F ^* is determined The A duty ratio is determined based on the target actuator force F ^* of the motor 54 determined as described above, and a control signal corresponding to the duty ratio is transmitted to the inverter 146. After the series of processes described above, one execution of the actuator control program ends.

  Based on the function of the suspension ECU 140 described above, the suspension ECU 140 changes the control state in the vibration damping control of the actuator 26 between the three specific control states by changing the sprung gain and the unsprung gain. The change part is included. The control state changing unit is configured to include a part for executing the processing of S1 to S5 of the actuator control program in the suspension ECU 140 of the suspension system 10.

≪Modification≫
i) First Modification Three specific control states are set in the suspension 10 of the above embodiment in the system 10, but two specific control states are set between them as in the system of the present modification. It can also be configured to be changeable. The two specific control states in this system are the riding comfort emphasis state and the ground contact emphasis state described in the above embodiment. That is, in this modification, the control state is changed on the line connecting S ₁ and S ₂ shown in FIG. 4, and the target control state S ^* is determined according to the following equation.
S ^* = (1−α) · S ₁ + α · S ₂

In the system of this modification, the actuator 26 is controlled by executing the actuator control program shown in the flowchart of FIG. 8 which is executed in place of the actuator control program of FIG. First, in S11 and S12, the weighting coefficient α is determined. As an index for determining the weighting coefficient α, the ground load variation is employed in the above embodiment, but the unsprung velocity Vg is employed in the present modification. That is, the weighting coefficient α is determined on the basis of the unsprung velocity effective value Vg _RMS by calculating the unsprung velocity effective value Vg _RMS within a set time traced back from the present time. The unsprung velocity Vg is also treated as an index relating to both the state of the road surface on which the vehicle travels and the state of vibration occurring in the vehicle, as with the ground load fluctuation. FIG. 9 is a diagram showing the relationship between the unsprung velocity effective value Vg _RMS and the weighting coefficient α. In this system, based on the weighting coefficient α determined in this way, the sprung gain Cs and the unsprung gain Cg in the target control state S ^* are expressed by the above formula S ^* = (1−α) · S ₁ + α · S ₂
It is decided according to. The relationship between the unsprung velocity effective value Vg _RMS and the weighting coefficient α is the same as the relationship between the ground load fluctuation effective value f _RMS and the weighting coefficient α shown in FIG. When the vehicle starts to move, that is, when the road surface on which the vehicle begins to deteriorate or when the vehicle starts to vibrate, the control state changes from the riding comfort emphasis state S ₁ to the grounding emphasis state S ₂ side. Therefore, the controllability and stability of the vehicle are effectively secured.

ii) Second Modification As in the first modification, this modification is configured such that two specific control states are set and can be changed between them. The two specific control states are the riding comfort emphasis state and the power generation amount emphasis state described in the above embodiment. That is, in this modification, the control state is changed on the line connecting S ₁ and S ₃ shown in FIG. 4, and the target control state S ^* is determined according to the following equation.
S ^* = (1−β) · S ₃ + β · S ₁
By the way, instead of the above-mentioned ride emphasis state, a ground contact emphasis state may be adopted, and an intermediate control state between the ride comfort emphasis state and the ground contact emphasis state (S ₁ and S shown in FIG. 4). ₂ ), that is, a comprehensive performance emphasis state determined by emphasizing the overall performance of the vehicle including ride comfort and ground contact.

In this modification, the actuator 26 is controlled by executing the actuator control program shown in the flowchart of FIG. 10 which is executed in place of the actuator control program of FIG. First, in S21 to 23, the weighting coefficient β is determined. The weighting coefficient β is determined based on the average value E of the charge amount, similarly to the second weighting coefficient in the above-described embodiment, and the target control state S which is an appropriate control state based on the determined weighting coefficient β. ^* sprung gain Cs and unsprung gain Cg in the above equation ^{S * = (1-β)} · S 3 + β · S 1
Determined according to.

However, in the system of the present modification, the relationship between the average value E of the charge amount and the second weighting coefficient β is as shown in FIG. 11 instead of that shown in FIG. That is, in the system of this modification, as shown in this figure, the weighting coefficient β is determined whether the charge amount E is increasing or decreasing within the set time traced back from the present time, and increases. When it is determined that the curve is convex, the curve is changed on the upwardly convex curve, and when it is decreased, the curve is changed on the downwardly convex curve. Accordingly, in the present system, when the charging amount of E tends to increase, even when the charge amount E is small, the control state is relatively large from the power generation amount focus state S ₃ to ride emphasis state S ₁ side If the charge amount E tends to decrease, the control state is relatively large from the riding comfort emphasis state S ₁ to the power generation amount emphasis state S ₃ side even when the charge amount E is large. Will be shifted.

(B) Second Embodiment Since the vehicle suspension system of the second embodiment has the same hardware configuration as the system of the first embodiment, in the description of the present embodiment, the system of the first embodiment. Constituent elements having the same functions as those indicated by the same reference numerals are used to indicate corresponding elements, and the description thereof is omitted. The system of this embodiment is different from the system of the first embodiment in the control by the ECU 140, specifically, the vibration damping control by the ECU 140 is different from the system in the first embodiment. Specifically, in the system of the first embodiment, three specific control states are set, but in the system of the present embodiment, two specific control states are set and can be changed between them. Yes. Hereinafter, a method for determining a vibration damping component in vibration damping control will be described in detail.

Of the two specific control states set in the system of the present embodiment, the first specific control state is a control state in which the balance between the riding comfort of the vehicle and the grounding property of the wheels is relatively good. This is a state of emphasizing the overall performance determined with emphasis on the overall performance of the vehicle including the performance. This comprehensive performance emphasis state is control in which the sprung gain Cs ₁ and the unsprung gain Cg ₁ are set to values in consideration of the balance between the riding comfort and the ground contact. That is, the vibration damping component in the comprehensive performance-oriented state is determined according to the following equation.
F _V = Cs ₁・ Vs−Cg ₁・ Vg

The second specific control state, which is another specific control state, is a power generation dedicated state in which the motor 54 is exclusively in the power generation state. This power generation dedicated state is a control state in which a resistance force is generated according to the relative motion speed (stroke speed) between the sprung portion and the unsprung portion, and the sprung gain and the unsprung gain have the same value, and The control state is set to a value smaller than the attenuation coefficient when the energization terminals of the motor 54 are short-circuited. Specifically, the sprung gain Cs ₂ and the unsprung gain Cg ₂ in the power generation-dedicated state are set to a half of the damping coefficient C obtained at the time of short circuit. It is determined.
F _V = (C / 2) · (Vs−Vg)
In the power generation dedicated state, since the sprung gain Cs ₂ and the unsprung gain Cg ₂ are set to the same value, no matter what direction the vibration of the sprung portion and the unsprung portion is, A damping force can be generated only for relative movement. Further, since the set value of the attenuation coefficient is 1/2 the attenuation coefficient C at the time of short circuit, the relative operation speed, that is, the generated electric energy with respect to the stroke speed, is Even speed is maximum.

In the system of the present modification, the control state is changed between the two specific control states. Specifically, the vibration attenuation component to be generated in the target control state is the vibration attenuation component of those specific control states. Is determined by weighting with a coefficient γ, that is, according to the following equation.
F _V = γ · (Cs ₁ · Vs−Cg ₁ · Vg) + (1−γ) · (C / 2) · (Vs−Vg)
This weighting coefficient γ is changed based on an index relating to the state of vibration occurring in the vehicle and the state of charge of the battery 150. Specifically, the unsprung speed Vg is adopted as an index relating to both the road surface condition and the vibration condition, and the effective value Vg _RMS of the unsprung speed within a set time retroactive from the present time is calculated and the unsprung _mass is calculated. A weighting coefficient γ is determined based on the velocity effective value Vg _RMS . FIG. 12 is a diagram showing the relationship between the unsprung velocity effective value Vg _RMS and the weighting coefficient γ. In the case where the degree of vibration input to the wheel is severe, it is desirable that the overall performance is emphasized in order to suppress the vibration. In this embodiment, as the unsprung velocity effective value Vg _RMS increases, By setting the weighting coefficient γ to a value close to 1, the control state is set to a control state closer to the overall performance-oriented state than the power generation dedicated state.

Further, the weighting coefficient γ is corrected according to the following equation in accordance with the charge amount E of the battery 150 as an index relating to the state of charge of the battery 150.
γ = k ・ γ
FIG. 13 is a diagram illustrating a relationship between the charge amount E and the correction coefficient k. When the charge amount E of the battery 150 is small, it is desirable that the amount of power regenerated in the battery 150 is large. In this embodiment, the smaller the charge amount E is, the smaller the correction coefficient k is. . That is, in this embodiment, even when the unsprung velocity effective value is large, when the charge amount E is small, as shown by the one-dot chain line in FIG. γ is reduced to a control state close to the power generation dedicated state.

  In the system of the present embodiment, as in the first embodiment, the ECU 140 changes the control state in the vibration damping control of the actuator 26 between the specific control states by changing the sprung gain and the unsprung gain. The control state changing unit is included. Therefore, the system according to the present embodiment can change the control state in the vibration damping control of the actuator 26 to an appropriate control state according to the situation where the vehicle is currently placed.

1 is a schematic diagram illustrating an overall configuration of a vehicle suspension system according to a first embodiment. It is front sectional drawing which shows the spring absorber Assy shown in FIG. FIG. 3 is a circuit diagram of a drive circuit or the like that controls an electromagnetic motor included in the actuator of FIG. 2. FIG. 2 is a diagram defining a control state of vibration damping control in the suspension electronic control unit shown in FIG. 1 as a point on a coordinate plane with a sprung speed corresponding gain and a unsprung speed corresponding gain as coordinate axes. It is a figure which shows the relationship between the 1st weighting coefficient used for control which changes the control state of vibration damping control, and the effective value of a ground-contact load fluctuation | variation. It is a figure which shows the relationship between the 2nd weighting coefficient used for control which changes the control state of vibration damping control, and charge amount. It is a flowchart showing the actuator control program performed by the suspension electronic control unit shown in FIG. It is a flowchart showing the actuator control program performed by the suspension electronic control unit of the suspension system of a 1st modification. It is a figure which shows the relationship between the weighting coefficient used for control which changes the control state of vibration damping control, and the effective value of unsprung speed. It is a flowchart showing the actuator control program performed by the suspension electronic control unit of the suspension system of a 2nd modification. It is a figure which shows the relationship between the weighting coefficient used for control which changes the control state of vibration damping control, and charge amount. It is a figure which shows the relationship between the weighting coefficient used for control which changes the control state of the vibration damping control in the suspension system for vehicles of 2nd Example, and the effective value of unsprung speed. It is a figure which shows the relationship between the weighting coefficient shown in FIG. 12, and the correction coefficient for correcting it.

Explanation of symbols

  10: Vehicle suspension system 20: Spring absorber assembly 22: Lower arm (lower part of spring) 24: Mount part (upper part of spring) 26: Actuator 28: Air spring 50: Screw rod (male thread part) 52: Nut (female thread part) 54 : Electromagnetic motor 80: Air supply / discharge device 140: Suspension electronic control unit (control device) 146: Inverter (drive circuit) 148: Converter 150: Battery 162: Vehicle speed sensor 164: Stroke sensor 170: Operating angle sensor 172: Longitudinal acceleration sensor 174: lateral acceleration sensor 176: longitudinal acceleration sensor (on spring) 178: longitudinal acceleration sensor (under spring) 184 charge amount sensor

Claims (14)

A suspension spring disposed between the spring top and the spring bottom;
An electromagnetic shock absorber that is arranged in parallel with the suspension spring and has an electromagnetic motor and generates resistance and propulsive force against the relative movement of the upper and lower springs depending on the force of the electromagnetic motor;
The spring force that is generated by the shock absorber is determined based on the sprung speed and the sprung speed corresponding gain that is the control gain corresponding to the sprung speed. A control device that controls the shock absorber so as to have a force including an unsprung speed dependent component that is determined based on a unsprung speed corresponding gain that is a control gain corresponding to the unsprung speed. A suspension system,
The control device is
By changing the sprung speed corresponding gain and the unsprung speed corresponding gain, the control state of the shock absorber is changed to a plurality of specific values in which the sprung speed corresponding gain and the unsprung speed corresponding gain are set to specific values. A vehicle suspension system comprising a control state changing unit that changes between control states.   At least one of the plurality of specific control states is: (a) a ride comfort-oriented state determined with emphasis on good ride comfort of the vehicle; and (b) focus on good wheel grounding. (C) the overall performance emphasis state determined with emphasis on the overall performance of the vehicle including the ride comfort of the vehicle and the grounding performance of the wheels, and (d) the electromagnetic motor 2. The vehicle according to claim 1, wherein the vehicle is selected from one of a power generation amount-oriented state determined with an emphasis on a large amount of generated power and (e) a power generation-only state in which the electromagnetic motor is exclusively in a power generation state. Suspension system.   The control state changing unit is configured to change the shock based on one or more indicators relating to a road surface on which the vehicle travels, a vibration state generated in the vehicle, or a charge state of a power source connected to the electromagnetic motor. The vehicle suspension system according to claim 1 or 2, wherein the control state of the absorber is changed.   The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain to the values of the sprung speed corresponding gain and the unsprung speed corresponding gain set for each of the plurality of specific control states. The suspension system for a vehicle according to claim 3, wherein the control state of the shock absorber is changed by determining the weight based on the one or more indices.   The control state changing unit is an indicator relating to the control state of the shock absorber, one of a state of a road surface on which the vehicle travels, a state of vibration generated in the vehicle, and a state of charge of a power source connected to the electromagnetic motor The vehicle suspension system according to claim 1 or 2, wherein the vehicle suspension system is changed between a first specific control state and a second specific control state, each of which is the specific control state.   The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain for each of the first specific control state and the second specific control state. 6. The vehicle suspension system according to claim 5, wherein the control state of the shock absorber is changed by determining the weight based on the index with respect to the value of the lower speed corresponding gain.   The control state change unit responds to the sprung speed by weighting according to a rule such that the sprung speed corresponding gain and the unsprung speed corresponding gain determined in response to the change of the index change nonlinearly. The vehicle suspension system according to claim 6, wherein a gain and the unsprung speed corresponding gain are determined.   The weighting is based on a rule such that as the value of the index increases, the gradient of the change in the sprung speed corresponding gain and the unsprung speed corresponding gain with respect to the change in the index increases or decreases. Item 8. The vehicle suspension system according to Item 7.   In the situation where the value of the index increases according to the rule that the gradient increases as the value of the index increases in one of the situations where the value of the index increases or decreases. 9. The vehicle suspension system according to claim 8, wherein the vehicle suspension system follows a rule that the gradient decreases as the value of the index increases. The first specific control state is a ride comfort-oriented state determined with emphasis on good ride comfort of the vehicle, and the second specific control state has good grounding performance of wheels. It is in a grounding-oriented state determined with emphasis on
The control state changing unit changes the control state of the shock absorber based on an index relating to either a road surface on which the vehicle travels as the index or a vibration state generated in the vehicle. The vehicle suspension system according to any one of claims 5 to 9. The first specific control state is determined with emphasis on (a) a ride comfort-oriented state determined with an emphasis on good ride comfort of the vehicle and (b) an excellent wheel grounding property. And (c) an overall performance emphasis state determined with emphasis on the overall performance of the vehicle including the ride comfort of the vehicle and the ground contact performance of the vehicle. (2) A specific control state includes (d) a power generation amount priority state that is determined with an emphasis on an increase in power generation amount of the electromagnetic motor, and (e) a power generation dedicated state in which the electromagnetic motor is exclusively in a power generation state. Be one of the
The control state change unit changes the control state of the shock absorber based on an index relating to a charging state of a power source connected to the electromagnetic motor as the index. The vehicle suspension system according to claim 1.   The control state changing unit is configured to change a control state of the shock absorber to any one of a state of a road surface on which the vehicle travels, a state of vibration generated in the vehicle, and a state of charge of a power source connected to the electromagnetic motor. 3. The method according to claim 1, wherein each of the indices is changed between a first specific control state, a second specific control state, and a third specific control state, which are the specific control states, based on one index. Vehicle suspension system.   The control state changing unit sets the sprung speed corresponding gain and the unsprung speed corresponding gain for each of the first specific control state and the second specific control state. The sprung speed corresponding gain and the unsprung speed corresponding gain determined by the first weighting based on one of the two indices for the lower speed corresponding gain and the third specific control state are set. The control state of the shock absorber is changed by determining by the second weighting based on the other of the two indices with respect to the value of the sprung speed corresponding gain and the unsprung speed corresponding gain. The vehicle suspension system according to claim 12. One of the first specific control state and the second specific control state is a ride comfort-oriented state determined with emphasis on good ride comfort of the vehicle, and the other is good wheel grounding performance. The third specific control state is a power generation amount emphasizing state determined with emphasis on an increase in the amount of power generated by the electromagnetic motor, and the grounding emphasis state determined with emphasis on being present. It is considered as one of the power generation dedicated states where the electromagnetic motor is exclusively in the power generation state,
The control state changing unit includes the first weighting based on an index relating to any one of a state of a road surface on which the vehicle travels as one of the two indices and a state of vibration occurring in the vehicle, and the two indices. The suspension system for a vehicle according to claim 13, wherein the control state of the shock absorber is changed by the second weighting based on an index relating to a charging state of a power source connected to the electromagnetic motor as the other of the electromagnetic motors. .

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