JP2007302211A - Suspension system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical suspension system properly suppressing power consumption of an electromagnetic absorber. <P>SOLUTION: A suspension device 19 has the electromagnetic absorber 20, and an electronic control unit (ECU) 100 controlling a damping force generated by the electromagnetic absorber 20. The ECU 100 determines a target value F of the damping force including a damping force component with respect to a sprung member 200 and a damping force component with respect to an unsprung member 202. Further, the ECU determines a gain of a sprung damping force component and a gain of an unsprung damping force component for determining the target value F of the damping force, based on road surface conditions or the like. Basically, in traveling on a rough road, both of the two gains are increased to perform a road holding emphasizing control, and in travelling on a smooth road, the both of the two gains are decreased to perform an electric power saving control, so that road holding in traveling on the rough road is secured and the power consumption in traveling on the smooth road is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a suspension system provided with a suspension device that generates a force that causes an unsprung member and an unsprung member to approach and separate with an electromagnetic absorber.

The electromagnetic absorber is a device that dampens the sprung member and the unsprung member by the driving force of an electromagnetic actuator such as an electromagnetic motor. For this reason, for example, as in a conventional fluid resistance type shock absorber, not only passively generates a force for braking the relative motion of the sprung member and the unsprung member, but also a force for driving the relative motion. Can be generated, and control suitable for the situation can be actively performed. Such a suspension device having an electromagnetic actuator is called, for example, an electromagnetic suspension device, and has been conventionally studied in order to realize so-called skyhook model control and the like. Examples of the electromagnetic suspension device are described in the following Patent Documents 1 to 3, respectively. In addition, the electromagnetic suspension device can generate, for example, a force that attenuates vibration (due to approach / separation) between the vehicle body (sprung member) and a wheel (unsprung member) by an electromagnetic actuator. It is not always necessary to supply power. For example, the damping force can also be generated by causing an electromagnetic actuator to generate power. Patent Document 1 described below describes a technique for reducing power consumption by facilitating power storage in a battery by power generation of an electromagnetic actuator when damping vibration, that is, facilitating power regeneration. Patent Document 3 below describes a technique for determining whether or not the vehicle is traveling on a rough road based on the amount of power supplied to the electromagnetic actuator and the supply time.
Japanese Patent Laid-Open No. 2003-102425 JP 2005-262939 A JP 2005-35490 A

  Further, in Patent Document 1, the force generated by the electromagnetic actuator is reduced on the condition that turning steering or acceleration / deceleration is not performed in a state where the vehicle speed exceeds a set speed (for example, when traveling on a highway). Thus, a technique for reducing power consumption is described. However, there is a problem that power consumption cannot be reduced when the vehicle speed is less than or equal to a specified value (for example, when traveling on a general road). Further, the output of the electromagnetic suspension device is determined simply based on the stroke speed (relative speed between the sprung member and the unsprung member), and the weight of the vibration suppression of the sprung member and the vibration suppression of the unsprung member is calculated. I can't change it. Furthermore, the power consumption is reduced by simply lowering the output of the electromagnetic suspension device, and no consideration is given to ride comfort and wheel grounding, leaving room for improvement. In Patent Documents 2 and 3, there is no description about power generation by an electromagnetic actuator, and power consumption for operating the electromagnetic actuator becomes a problem.

  Each of the problems described above is an example of a problem that can be an obstacle to improving the practicality of the conventional suspension system, and there is room for improvement from various viewpoints in the suspension system. That is, it is possible to improve the practicality by improving the conventional suspension system. The present invention has been made in view of such circumstances, and an object thereof is to obtain a more practical suspension system.

  In order to solve the above-described problems, the suspension system of the present invention is configured so that the electromagnetic absorber provided in the suspension device has a “sprung damping force component” that is a damping force component based on the displacement speed of the sprung member and the displacement of the unsprung member. And a control device that controls to generate a force including a “unsprung damping force component” that is a damping force component based on speed, and the control device controls the electromagnetic absorber with “unsprung damping force component gain”. "Is greater than the set value and switching is switched between the second control in which" the gain of the unsprung damping force component "is less than or equal to the set value.

  According to the suspension system of the present invention, for example, it is possible to switch between the first control suitable for reducing the contact load fluctuation rate and the second control suitable for reducing power consumption according to the situation. The power consumption can be appropriately reduced according to the situation. That is, according to the present invention, a more practical suspension system can be obtained.

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 for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention 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 each of the following paragraphs, (1) is in claim 1, (2) is in claim 2, (5) and (6) are combined in claim 3, and (9) ) Corresponds to claim 4, and (10) corresponds to claim 5.

(1) A spring for generating a force for separating the sprung member and the unsprung member, and an electromagnetic absorber for generating a force for approaching and separating the sprung member and the unsprung member together with the spring. A constructed suspension device;
The electromagnetic absorber generates a force including a sprung damping force component that is a damping force component based on the displacement speed of the sprung member and an unsprung damping force component that is a damping force component based on the displacement speed of the unsprung member. And a suspension system comprising a control device for controlling the electromagnetic absorber,
The control device is
Control of the electromagnetic absorber includes first control in which the gain of the unsprung damping force component is larger than a set value, and second control in which the gain of the unsprung damping force component is set to a value equal to or less than the set value. Suspension system, characterized in that it is configured to switch between.

  According to the suspension device described in this section, for example, the sprung member can be elastically supported by the spring, and the vibration of the sprung member and the unsprung member can be suppressed by the electromagnetic absorber. The electromagnetic absorber of this section can have, for example, an electromagnetic motor (brushless, with brush, etc., the mode of the motor is not particularly limited) as a driving force source. And, like a conventional fluid resistance type shock absorber, not only simply generates a damping force according to the relative speed (approach / separation speed) between the sprung member and the unsprung member, A force in a direction that promotes relative displacement with the unsprung member can also be generated. Therefore, the suspension device is suitable for performing so-called skyhook model control and the like.

  In the Skyhook model control, there is a model that controls only the vertical vibration of the sprung member and does not suppress the vibration of the unsprung member, but the riding comfort is good, but the grounding property of the wheel is bad. There are drawbacks. On the other hand, the aspect described in this section is control that suppresses vertical vibration of both the sprung member and the unsprung member in the skyhook model control. Specifically, the gain of the sprung damping force component (hereinafter referred to as “sprung gain”) and the gain of the unsprung damping force component (hereinafter referred to as “unsprung gain”) are individually set. Thus, the degree of vibration suppression of the sprung member and the degree of vibration suppression of the unsprung member can be individually adjusted. Therefore, only the sprung damping force component can be changed, or only the unsprung damping force component can be changed. Of course, both the sprung damping force component and the unsprung damping force component can be increased or decreased. Therefore, the sprung gain and unsprung gain (hereinafter sometimes referred to as “two gains”) can be set appropriately, and it is possible to keep the grounding property good and ride comfort. It is.

  In the aspect described in this section, the magnitude of the unsprung gain can be changed by switching the control of the electromagnetic absorber. Conversely, control can be switched by changing the gain. In the first control, the unsprung gain is set larger than the set value, and the degree of vibration suppression of the unsprung member is relatively high. Therefore, the “ground load variation rate” of the wheel is relatively small, and the grounding property is good. is there. However, since more energy is spent for damping the unsprung member, the power consumption increases compared to the second control in which the unsprung gain is set to a set value or less. On the other hand, in the second control, the unsprung gain is made relatively small, and “power consumption of the electromagnetic absorber” can be reduced. However, since the degree of vibration suppression of the unsprung member is reduced as compared with the first control, for example, the grounding property during traveling on a rough road (details will be described later) is reduced. In other words, it is difficult to achieve both grounding performance and reduction in power consumption when traveling on rough roads. However, as will be described later, for example, by appropriately switching the control according to the road surface condition, the amount of battery storage, etc. The power consumption can be appropriately reduced. Note that the set value is, for example, the lower limit value of the unsprung gain that can maintain good grounding performance on rough roads, the upper limit value of the unsprung gain that can effectively reduce power consumption, and the like. Can do.

  According to the suspension system described in this section, for example, depending on the situation, switching between the first control suitable for reducing the ground load fluctuation rate and the second control suitable for reducing power consumption is performed. It is possible to reduce power consumption appropriately according to the situation. That is, according to the aspect described in this section, a more practical suspension system can be obtained.

  Note that the power consumption in the embodiment described in this section is not limited to reducing the power consumption of the electromagnetic absorber by reducing the power supplied to the electromagnetic absorber, but also storing the power generated by the electromagnetic absorber in the battery. It also includes reducing the power consumption as a whole by facilitating the operation, that is, facilitating the regeneration of the electric power. Note that the amount of reduction in power consumption increases as the unsprung gain value in the second control is smaller than in the first control, but on the other hand, the grounding performance on rough roads decreases. Further, the value of the unsprung gain in the second control can be set to a magnitude of about one-half, about one-fourth, or about one-eighth of the unsprung gain in the first control, for example.

  The spring described in this section may be configured by a spring member such as a coil spring, a torsion spring, a leaf spring, or the like. Also, for example, an air chamber (gas chamber) that contains gas, such as an air spring, and generates elastic force by changing the volume of the air chamber as the vehicle body and wheels approach and separate from each other. can do. The electromagnetic absorber described in this section includes, for example, a rotary driving force source such as a rotary electromagnetic motor and a motion conversion device that converts the rotary motion thereof into a linear motion, a linear electromagnetic motor, or the like It is possible to have a direct-acting driving force source.

(2) The control device
Item (1) is configured to switch control of the electromagnetic absorber based on at least one of a road surface state, a storage state of a battery that is a power source of the electromagnetic absorber, and a traveling state of the vehicle. Suspension system.

(3) The controller is
The first control is performed when the vibration intensity in the resonance frequency region of the unsprung member exceeds the set strength, and the vibration strength in the resonance frequency region of the unsprung member is in the road surface state that is equal to or less than the set strength. The suspension system according to item (1) or (2), which is configured to perform the second control.

(4) The controller is
Items (1) to (3) are configured to perform the first control when the storage amount of the battery as the storage state is larger than a set amount, and to perform the second control when the amount is less than the set amount. The suspension system according to any one of items 1).

  The above three aspects will be described. Switching between the first control and the second control can be determined based on at least one of a road surface state, a battery storage state, and a traveling state. The road surface state can be determined in two stages, for example, a road surface state having relatively small unevenness and a road surface state having relatively large unevenness, or can be determined in three or more stages. When the road surface state is determined in two stages, for example, a road with a relatively rough road surface can be a “good road” and a road with a relatively large road surface can be a “bad road”. Specifically, the good road can be, for example, a general paved road with relatively little deterioration, and the expressway can be said to be a road with very little unevenness (very good road) among good roads. The bad road can be, for example, an unpaved road, a road surface where a seam of repair work exists even on a paved road, or a road that is relatively deteriorated due to deformation at a high temperature. When the control is switched based on the road surface condition, for example, the first control can be performed when traveling on a rough road, and the second control can be performed when traveling on a good road. In other words, when traveling on rough roads, the first load control can reduce the ground load variation rate, while when traveling on a good road with small road surface irregularities, the ground load variation due to the road surface Therefore, even if the unsprung gain is small, the grounding property is easily maintained, and the power consumption can be reduced by performing the second control.

  The determination of the road surface state can be made based on, for example, the vibration intensity in the resonance frequency region (resonance frequency and frequencies in the vicinity thereof) of the unsprung member. The unsprung member is likely to vibrate in its resonance frequency range, and when the vibration is large, it can be determined that the road surface is relatively uneven, that is, when traveling on a rough road. The vibration intensity can be a value based on, for example, acceleration and amplitude of vibration of the unsprung member. And, for example, determining the road surface condition based on the ratio of the time during which the vibration acceleration exceeds the set acceleration within the set time, the number of times the amplitude of the vibration exceeds the set value within the set time, etc. Can do. By determining the road surface state by such a method, it is possible to make a determination in accordance with the actual situation. Specifically, even on the same road, for example, the vibration intensity of the unsprung member may change depending on the traveling speed, etc. In such a case, the first control is performed when the vibration intensity is high, and the vibration intensity is low. In some cases, the second control can be performed. In other words, the road surface condition in this section includes the meaning of the degree of vibration of the unsprung member due to the input from the road surface.

  In addition, for example, when switching the control based on the battery storage state, for example, in the state where the battery storage amount is large, the necessity for reducing power consumption is low, so the first control with a small ground load fluctuation rate is performed, The second control can be performed in a state where the storage amount of the battery is small. Furthermore, when the control is switched based on both the road surface state and the battery storage state, either state may be prioritized. The mode of control switching is, for example, that the first control is performed only when traveling on a rough road and the amount of stored electricity is large, and other situations (even when traveling on a good road or traveling on a rough road, the amount of stored power is small. By performing the second control in (Situation), it is possible to achieve a power-saving switching control that increases the degree of the second control and further reduces the power consumption. In addition, for example, the second control is performed only when traveling on a good road and the amount of power storage is small, and in other situations (when the power storage amount is large even when traveling on a bad road or on a good road), the first control is performed. By performing the control, it is possible to perform various controls such as a grounding-oriented switching control that increases the degree of the first control and keeps the grounding as good as possible. That is, according to the above three aspects, power consumption can be reduced even when the traveling speed is low, and power consumption can be more appropriately reduced according to the purpose.

  When switching the control based on the running state, for example, in the turning state or acceleration / deceleration state (acceleration state, deceleration state), the first control is performed with emphasis on grounding, and the vehicle is turning or accelerating / decelerating. The second control can be performed in a steady straight traveling state that is a traveling state that can be regarded as non-existent (in other words, a traveling state that can be regarded as traveling substantially straight at a constant speed). In addition, a state in which relatively gentle turning or acceleration / deceleration is performed can be regarded as a steady straight traveling state. In the case where the control is switched based on two or more of the road surface state, the battery storage state, and the traveling state, any state may be prioritized. In addition, for example, each state is discriminated into three or more stages, and when the condition is severest, for example, when the road surface state is the worst among a plurality of stages, the road surface state is given priority, and the amount of power storage is the minimum amount. In this case, it is possible to give priority to the storage state, and to give priority to the traveling state when the traveling state is a sudden acceleration state or a sudden turning state.

(5) The control device
The suspension system according to any one of (1) to (4), wherein a gain of the sprung damping force component in the second control is configured to be smaller than a value in the first control.
(6) The control device
The suspension according to item (5), wherein in the second control, a ratio of a gain of the sprung damping force component to a gain of the unsprung damping force component is made larger than the ratio in the first control. system.

  The two aspects will be described. In the second control, the power consumption can be further reduced by decreasing the sprung gain together with the unsprung gain. Note that, for example, when traveling on a good road, the vibration on the spring is relatively small, so that the riding comfort tends to be kept relatively good even if the sprung gain is reduced. In the second control, for example, by making the ratio of the sprung gain to the unsprung gain larger than the ratio in the first control, for example, it becomes easy to maintain a good riding comfort. For example, when the road surface condition is the same, the ride comfort is a ratio (hereinafter referred to as “sprung transmission ratio”, “sprung transmission ratio”, etc.) in which vibration input from the road surface is transmitted to the sprung member. May be evaluated). In particular, it is desirable to evaluate the ride comfort using the sprung transmission ratio of vibrations in the resonance frequency region (resonance frequency and frequencies in the vicinity thereof) of the sprung member. In addition, the “decrease rate of the sprung gain” can be, for example, a value obtained by dividing the amount of decrease in the sprung gain by the value of the sprung gain in the first control.

(7) The control device
The gain of the sprung damping force component in the second control is smaller than the gain of the sprung damping force component in the first control, and the vibration in the resonance frequency range of the sprung member input from the road surface is a spring. Items (1) to (6) are configured to suppress a sprung transmission ratio, which is a ratio transmitted to the upper member, from becoming larger than the sprung transmission ratio in the first control. The suspension system according to any one of the above.

  When the sprung gain is decreased together with the unsprung gain, the sprung transmission ratio of vibrations in the resonance frequency region (resonance frequency and frequencies in the vicinity thereof) of the sprung member tends not to increase. Based on this tendency, for example, the sprung gain in the second control can be reduced without increasing the sprung transmission ratio of vibration in the resonance frequency region of the sprung member. Further, for example, the sprung gain in the second control can be reduced while keeping the increase in the sprung transmission ratio of vibration small (for example, the increased rate is 20% or less, 40% or less, etc.). For that purpose, for example, it is desirable to make the ratio of the sprung gain to the unsprung gain in the second control larger than the ratio in the first control. That is, when switching from the first control to the second control, it is desirable to make the reduction ratio of the sprung gain smaller than the reduction ratio of the unsprung gain. The gain reduction rate can be, for example, a value obtained by dividing the reduction amount of the sprung gain by the value of the sprung gain in the first control. The same can be applied to the amount of decrease in the unsprung gain. The control device described in this section suppresses an increase in the sprung transmission ratio of vibration in the resonance frequency region of the sprung member, that is, reduces the sprung gain while suppressing deterioration of the ride comfort, thereby reducing power consumption. Can be reduced.

(8) The control device
The gain of the unsprung damping force component in the second control is set to a value that is smaller than the set value and that is insufficient for ground contact when traveling on rough roads (1) to (7) The suspension system according to any one of the items.

Since the unsprung gain affects the degree of vibration suppression of the unsprung member, it has a large influence on the ground load variation rate. Then, the decrease in unsprung gain increases the contact load variation rate, which causes, for example, a decrease in contact performance when traveling on rough roads. However, for example, when traveling on a good road with relatively small road surface irregularities, the ground load variation is relatively small even if the unsprung gain is small. Power consumption can be reduced while maintaining good. In other words, the power consumption can be effectively reduced by deliberately reducing the unsprung gain in the second control until the ground load variation rate becomes relatively large at the expense of grounding performance when traveling on rough roads. . In addition, it is desirable that a good grounding property is obtained when traveling on a good road.
The ground load in this section can be, for example, a load that the unsprung member receives from the road surface. Also, the rate of change in the ground load in this section is, for example, the amount of change in the ground load when the unsprung member grounds on the road surface while vibrating vertically (for example, the maximum amount of decrease in the ground load). Value, average value of reduction amount, etc.) to the ground load when the vehicle is stationary. In addition, when the mode described in this section is applied to the above section (7), in the second control, compared to the first control, the increase in the sprung transmission ratio is suppressed, and the grounding when traveling on a rough road. By allowing the lack of performance, the power consumption of the electromagnetic absorber can be effectively reduced while keeping the ride comfort relatively good.

(9) The control device
In the second control, each value of the gain of the sprung damping force component and the gain of the unsprung damping force component is set to a value suitable for power regeneration by the electromagnetic absorber. The suspension system according to any one of (1) to (8).

  When both the sprung gain and the unsprung gain are decreased, electric power tends to be easily regenerated, and depending on the road surface state and the control mode, the amount of electricity stored in the battery can be increased by power generation of the electromagnetic absorber. In the aspect described in this section, since both the sprung gain and the unsprung gain are set to values that are relatively suitable for power regeneration, the effect of reducing power consumption is enhanced. Values suitable for power regeneration include, for example, a sprung gain and an unsprung gain, respectively, in a state where almost no power is supplied to the electromagnetic absorber (including a state where no power is supplied). It can be set to a value at which occurs and a value near it. In other words, the electromagnetic absorber is passively operated according to the approach / separation between the sprung member and the unsprung member, and as close as possible to a state in which a damping force is generated. In addition, when improving at least one of riding comfort and ground contact property, it is desirable to set at least one of the sprung gain and the unsprung gain to a relatively large value within a range suitable for the regeneration. .

(10) The suspension system includes the suspension device corresponding to each of the plurality of unsprung members,
The control device is
Any one of the items (1) to (9), wherein the control of the electromagnetic absorber of each of the plurality of suspension devices is individually switched between the first control and the second control. Suspension system described in.

  Usually, a vehicle is provided with a plurality of (for example, four) unsprung members. In the aspect described in this section, each of the plurality of unsprung members is connected to the sprung member by the suspension device of the present section. In the aspect described in this section, the vehicle body includes a plurality of sprung members, and the unsprung members corresponding to each of the plurality of sprung members are connected to the sprung members by the corresponding suspension device. Can be done.

  The control device described in this section can individually switch the control of the electromagnetic absorbers of the plurality of suspension devices. Therefore, for example, one to three of the four suspension devices can be controlled by the first control, and the remaining ones can be controlled by the second control. Thus, by switching the control for each suspension device, for example, when the road surface through which one of the left and right wheels of the vehicle passes is bad and the road surface through which the other wheel passes is good, The suspension device located in the first position can be subjected to the first control to keep the wheel grounding well, and the left and right suspension devices can be subjected to the second control to reduce power consumption. For example, even when the vehicle is traveling on a rough road, if the amount of power stored in the battery is small, the second control can be performed on some of the plurality of suspension devices to reduce power consumption.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is by no means limited to the following examples, and in addition to the following examples, there are various types based on the knowledge of those skilled in the art including the aspects described in the above [Aspect of the Invention] section. It can implement in the various aspect which gave the change and improvement of these.

1. Suspension device.
FIG. 1 schematically shows a suspension apparatus 10 included in a suspension system according to an embodiment of the claimable invention. The suspension system is provided with a plurality of suspension devices 10 (four in the present embodiment), and one of them will be described as a representative. The suspension device 10 includes a compression coil spring 16 (hereinafter abbreviated as “spring”) for elastically supporting a sprung member (vehicle body) and a sprung member (part of the vehicle body) by electromagnetic driving force. ) And an unsprung member (wheel, axle, steering knuckle, etc.).

  The electromagnetic absorber 20 includes an extendable cylinder 22 and an electromagnetic motor 24 (hereinafter sometimes abbreviated as “motor”) as an electromagnetic driving force source that generates a force for expanding and contracting the cylinder 22. Yes. The cylinder 22 includes an outer tube 30 whose lower end is open, and an inner tube 32 that is inserted into the outer tube 30 from below. A set clearance is secured between the outer tube 30 and the inner tube 32, and the cylinder 22 can be expanded and contracted by enabling the relative movement of the outer tube 30 and the inner tube 32 smoothly. A mounted member 40 on which a part 36 of the vehicle body is mounted is attached to the upper portion of the outer tube 30. A motor 24 is fixed to the top of the mounted member 40. The motor shaft 42 of the motor 24 extends downward, and is rotatable through a bearing 46 above and below the large-diameter portion 44 and immovable in the axial direction.

  A portion below the large-diameter portion 44 of the motor shaft 42 is a ball screw shaft portion 50 in which a screw groove 48 into which a bearing ball is fitted is formed on the outer peripheral portion. The ball screw shaft portion 50 has a length that extends through the outer tube 30 to the inner side of the inner tube 32. On the other hand, a ball nut 52 for holding a bearing ball is fixed to the inner periphery of the upper end portion of the inner tube 32, and the ball nut 52 and the ball screw shaft portion 50 are screwed together via the bearing ball. . That is, when a rotational driving force is applied to the ball screw shaft portion 50 by the motor 24, a force for moving the ball nut 52 in the axial direction is generated. In this embodiment, a ball screw mechanism which is a kind of “motion converting device” is configured to include the ball screw shaft portion 50 and the ball nut 52.

  A lower holding member 56 that supports the lower end of the spring 16 is attached to the outer periphery of the inner tube 32. The spring 16 is sandwiched between a flange 58 and a lower holding member 56 provided on the mounted member 40 so as to elastically support a part 36 of the vehicle body. The lower end portion of the inner tube 32 is connected to a lower arm (not shown) that supports a member that holds the wheel, and the inner tube 32 moves up and down with respect to the vehicle body together with the wheel. With the configuration described above, the sprung member and the unsprung member are elastically connected, and a force for causing the sprung member and the unsprung member to approach and separate from each other by the driving force of the motor 24 is generated. ing.

  An acceleration sensor 60 (Gs) for detecting the vertical acceleration of the sprung member is disposed above the mounted member 40, and an acceleration sensor 62 (for detecting the vertical acceleration of the unsprung member is provided below the inner tube 32. Gg) is provided. Based on the detection values of these two sensors 60 and 62, the vertical displacement speeds of the sprung member and the unsprung member are acquired.

2. Electronic control unit.
As shown in FIG. 2, the electromagnetic absorber 20 of the suspension device 10 is controlled by an electronic control unit 100 (ECU, hereinafter simply referred to as “ECU 100”) provided therein. The ECU 100 is mainly configured by a computer including a CPU, a ROM, a RAM, and the like. The ECU 100 includes a lateral acceleration sensor 110, a vehicle speed sensor 112, an acceleration sensor 60 (Gs) for a sprung member, an acceleration sensor 62 (Gg) for an unsprung member, and a voltmeter that measures the voltage of a battery 120 mounted on the vehicle. Various sensors such as 122 are connected. The ECU 100 is connected to a band pass filter 126 so that a signal of the acceleration sensor 62 (Gg) can be acquired via the band pass filter 126. Therefore, the acceleration of vibration in the 10 Hz region (10 Hz and frequencies in the vicinity thereof) that is “vibration in the resonance frequency region of the unsprung member 202” in the present embodiment can be acquired. Although not shown, the various sensors are connected as necessary via a filter such as a low-pass filter so that high-frequency components such as noise are removed. In addition, an inverter 130 is connected to the ECU 100, and when various control commands are transmitted from the ECU 100 to the inverter 130, driving power is supplied from the inverter 130 to the motor 24 of the electromagnetic absorber 20. Note that power is supplied from the battery 120 to the inverter 130.

  In this embodiment, the electromagnetic motor 24 is a three-phase DC brushless motor and is energized and controlled by the inverter 130. The inverter 130 is a general one as shown in a circuit diagram in FIG. 3, and corresponds to each of the high potential side and the low potential side, and to each of the three phases (U, V, W) of the motor. Corresponding six switching elements UHC, ULC, VHC, VLC, WHC, WLC are provided. The controller CNT determines the motor rotation phase (electrical angle) from the detection signals of the three Hall elements H provided in the motor 24, turns on / off each switching element based on the motor rotation phase, and energizes each coil.・ Generate rotational torque by switching between de-energization. The energization pattern is switched according to the direction of the rotational torque of the motor 24. In addition, the inverter 130 changes the current supplied to the motor 24 by the controller CNT changing the duty ratio (on / off time ratio of the energization pulse) by PWM (pulse width modulation) control, and the rotation torque Change the size. For example, when the duty ratio is increased, the amount of energization current is increased, and the rotational torque generated by the motor 24 is increased. Note that a command signal including information on the rotation direction of the motor 24 and the magnitude of the torque is transmitted from the ECU 100 to the inverter 130. Each switching element of the inverter 130 is provided with a reflux diode in parallel. When the electric power generated by the electromagnetic absorber 20 is regenerated, the electric power is charged in the battery 120 through the return diode.

  In FIG. 2, various functional units of the ECU 100 are illustrated. Although the configuration of the ECU 100 is not clearly divided as shown in the figure, such a diagram is used in order to facilitate understanding of the function of the ECU 100. The ECU 100 includes a “storage unit 140” configured to include a ROM, a RAM, and the like. The storage unit 140 includes various programs such as a damping force control program and a road surface condition determination program, which will be described later, and various data. Is recorded (details will be described later). The ECU 100 also includes a “damping force control unit 150” that controls the damping force generated by each electromagnetic absorber 20. The damping force control unit 150 includes a “gain determining unit 152” that determines a gain of a damping force component based on the displacement speed of the sprung member and a gain of a damping force component based on the displacement speed of the unsprung member. The ECU 100 also includes a “reference information acquisition unit 160” that acquires information about various states that are referred to when determining the gain. The reference information acquisition unit 160 includes a “road surface state determination unit 162” that determines whether the road surface state is good, a “power storage amount determination unit 164” that determines whether the storage amount of the battery 120 is sufficient, and the vehicle is turning. And a “running state determination unit 166” that determines whether the vehicle is in a steady straight-running state, which is a traveling state that can be regarded as not turning or accelerating / decelerating. . The details of the above functional units will be described together with the explanation of the damping force control.

3. Control of electromagnetic absorber.
3.1. About damping force.
The control of the electromagnetic absorber 20 by the ECU 100 will be described. First, FIG. 4 shows a two-degree-of-freedom model in consideration of vertical vibration. In this figure, the sprung member 200 and the unsprung member 202 correspond to one wheel, and the vehicle has a plurality of sprung members 200 and a plurality of corresponding to a plurality of wheels (for example, four). And an unsprung member 202. The vehicle body includes a plurality of sprung members 200. The unsprung member 202 includes wheels, an axle, an axle carrier, and the like.

In the present embodiment, the spring 16 and the electromagnetic absorber 20 are arranged in parallel between the sprung member 200 and the unsprung member 202. An elastic force of the spring 16 and an approaching / separating force of the electromagnetic absorber 20 act between the sprung member 200 and the unsprung member 202. Note that the approach / separation force of the electromagnetic absorber 20 is a force for attenuating the vibrations of the sprung member 200 and the unsprung member 202, and may be simply referred to as “damping force”. The target value F of the damping force is obtained by the following formula.
[Formula 1] F = Cs · Xv2−Cg · Xv1
“Xv2” is the displacement speed of the sprung member 200, and “Xv1” is the displacement speed of the unsprung member 202. “Cs” is a gain of a damping force component that attenuates the vibration of the sprung member 200, that is, “sprung gain”, and “Cg” is a damping force component that attenuates the vibration of the unsprung member 202. Gain, or “unsprung gain”. In addition, X0 in a figure is a displacement of a road surface.

  The displacement speeds Xv2 and Xv1 of the sprung member 200 and the unsprung member 202 are acquired based on the detection values of the acceleration sensors 60 (Gs) and 62 (Gg), respectively. Note that when the displacement speed Xv1 of the unsprung member 202 is acquired, the detected value of the acceleration sensor 62 (Gg) that does not pass through the bandpass filter 126 is used. According to the above equation 1, when the sprung gain Cs and the unsprung gain Cg are determined, a damping force target value that is a target value of the damping force that the electromagnetic absorber 20 should generate is determined according to the displacement speeds Xv2 and Xv1. Can do.

3.2. Gain, power consumption, grounding and ride comfort.
First, the relationship between unsprung gain (Cg), power consumption, and grounding will be described. FIG. 5 schematically shows the relationship between unsprung gain and power consumption. From this figure, it is recognized that when the unsprung gain is increased, the power consumption increases, and when the unsprung gain is decreased, the power consumption tends to decrease. Further, when the unsprung gain is set to 0, the power consumption is not minimized, and a tendency that the power consumption is minimized at a value larger than 0 is recognized. In this embodiment, in order to effectively reduce the power consumption, the target is to make the power consumption smaller than the value indicated by the power consumption target line shown in the figure. Then, the unsprung gain Cg is set to a value within the power consumption reduction region (Cg ≦ Cg-max), which is a region where the unsprung gain Cg is less than or equal to Cg-max, thereby reducing the power consumption to a value less than or equal to the power consumption target line. be able to. Cg-max represents the maximum value that the unsprung gain can take in the range set for effectively reducing power consumption, that is, in the power consumption reduction region. Therefore, when there is no need to effectively reduce the power consumption, the unsprung gain can be set to a value outside the power consumption reduction region, that is, a value larger than Cg-max.

FIG. 6 schematically shows the relationship between the unsprung gain and the ground load variation rate (related to grounding property) of the unsprung member 202. From this figure, it can be seen that when the unsprung gain is increased, the ground load variation rate decreases, and when the unsprung gain is decreased, the ground load variation rate increases. Note that the smaller the grounding load variation rate, the greater the degree of vibration suppression of the unsprung member 202, and the grounding performance is improved if the road surface condition is the same. In this embodiment, the contact load fluctuation rate is obtained by the following equation.
[Formula 2] Grounding load fluctuation rate = 1-minimum grounding load at unsprung resonance / grounding load at rest (minimum grounding load at unsprung resonance =
Tire longitudinal spring coefficient x minimum value of tire deflection at unsprung resonance)
(Static contact load at rest = Tire longitudinal spring coefficient x Tire deflection at rest)

  Here, if the unsprung gain is a value within the power consumption reduction region of FIG. 5 (for example, Cga), the degree of vibration suppression of the unsprung member 202 is low because the ground load variation rate is relatively large. When driving on rough roads with many irregularities, the grounding property tends to be insufficient. In this embodiment, in order to maintain good grounding performance when traveling on rough roads, it is desirable to increase the unsprung gain so that the ground load variation rate of the unsprung member 202 is smaller than the grounding target line (for example, Cgb). The unsprung gain value Cgb is set so that the degree of damping of the unsprung member 202 is approximately the same as the degree of damping when a conventional fluid resistance type shock absorber is used (for example, ground load) The fluctuation rate is around 0.15). Since Cgb is set to a value (Cgb> Cg−max) that exceeds the power consumption reduction region, it is difficult to effectively reduce power consumption. In other words, if reduction of power consumption is prioritized, the grounding performance on rough roads will decrease, and if grounding performance is prioritized, power consumption will increase. Therefore, it is possible to achieve both reduction of power consumption and grounding performance on rough roads. It seems difficult. However, when traveling on a good road with relatively few irregularities, the vibration of the unsprung member 202 is small, and therefore relatively good grounding tends to be obtained even if the degree of vibration suppression of the unsprung member 202 is low.

  From the above, when traveling on rough roads, the unsprung gain is increased to a value (Cgb) in the grounding priority area to improve the grounding performance, while when traveling on good roads, the unsprung gain is decreased. Therefore, it is considered desirable to reduce the power consumption by setting the value (Cga) in the power consumption reduction region. In this embodiment, the power consumption reduction region (unsprung gain Cg ≦ Cg-max) and the grounding importance region (Cg> Cg-max) are adjacent to each other, and one boundary where the unsprung gain is Cg-max. It is demarcated by a line (FIG. 6). However, depending on conditions, for example, a curve indicating the relationship between the unsprung gain and the degree of damping of the unsprung mass, the maximum value Cg-max of the power consumption reduction region, the grounding target line, and the like change the positional relationship. Therefore, as described above, the power consumption reduction area and the grounding importance area are not necessarily partitioned by one boundary line. For example, as shown in FIG. 14, the power consumption reduction region (unsprung gain Cg ≦ Cg-max) and the grounding-oriented region (Cg ≧ Cg-min) do not belong to any of these two regions. Are located apart from each other (Cg-max <Cg <Cg-min), and these two regions are separated by two different boundary lines (Cg = Cg-max, Cg = Cg-min) There is also. Note that Cg-min in FIG. 14 indicates the lower limit value of the grounding-oriented region. In any case, in order to effectively reduce power consumption, it is difficult to avoid a decrease in grounding performance when driving on rough roads. Similarly, power consumption is required to improve grounding performance on rough roads. It is difficult to escape the increase.

Next, the relationship between sprung gain (Cs), power consumption, and riding comfort will be described. FIG. 7 schematically shows the relationship between the sprung gain and the power consumption. From this figure, it can be seen that the relationship between the sprung gain and the power consumption is substantially the same as the relationship between the unsprung gain and the power consumption. In FIG. 8, when the unsprung gain (Cg) is a value within the power consumption reduction region (Cga ≦ Cg−max), that is, when the unsprung gain is small, the sprung gain and the vibration suppression of the sprung member 200 are illustrated. The relationship with the degree (related to ride comfort) is schematically shown. In this figure, the degree of vibration suppression of the sprung member 200 is approximately the inverse of the sprung transmission ratio. The sprung transmission ratio is a ratio at which vibration input from the road surface to the wheel is transmitted to the sprung member 200. And when a road surface state is the same, riding comfort improves, so that a sprung transmission ratio is small. The sprung transmission ratio is a sprung transmission ratio of vibration in the 1 Hz region (1 Hz and its vicinity), which is an example of “vibration in the resonance frequency region of the sprung member 200” in the present embodiment. The sprung transmission ratio is obtained by the following equation.
[Formula 3] Sprung transmission ratio =
Acceleration of vibration in 1 Hz region of sprung member / Acceleration of vibration in 1 Hz region input from road surface

  From this figure, it can be seen that increasing the sprung gain increases the degree of vibration suppression, and decreasing the sprung gain decreases the degree of vibration suppression. In the present embodiment, when the degree of vibration suppression on the spring is above the ride comfort target line shown in the figure, the sprung transmission ratio is small, and the ride comfort is relatively good. Accordingly, the ride comfort can be improved by setting the sprung gain to a value within the ride comfort good region which is the region of Cs-min or more in the drawing. On the other hand, power consumption can be effectively reduced by setting the sprung gain to a value in the power consumption reduction region which is a region of Cs-max or less in the drawing. From the above, by setting the sprung gain to the value Csa of the region where the riding comfort favorable region and the power consumption reduction region overlap (Cs-min ≦ Cs ≦ Cs-max), the riding comfort is improved, Power consumption can be effectively reduced. In other words, unlike the relationship between the grounding property and the reduction of power consumption when traveling on rough roads, by appropriately setting the sprung gain Cs, the ride comfort (that is, vibration suppression on the spring) and the power consumption are reduced. It is possible to achieve both. The sprung gain value Csa is set so that the vibration suppression degree of the sprung member 200 is approximately the same as the vibration suppression degree when a conventional liquid shock absorber is used (for example, the sprung mass (Transmission ratio is around 0.5). Further, when the sprung mass damping degree becomes close to 0 due to resonance of the sprung member 200, the sprung transmission ratio becomes larger than 1.

  In FIG. 9, when the unsprung gain (Cg) is a value (Cgb ≧ Cg−max) within the grounding-oriented region, that is, when the unsprung gain is large, the unsprung gain (Cs) and the unsprung member 200. The relationship with the degree of vibration suppression (related to ride comfort) is schematically shown. The relationship when the unsprung gain is small is indicated by a two-dot chain line. When the unsprung gain is large, it is recognized that the slope of the graph indicating the degree of vibration suppression on the spring tends to be smaller than when the unsprung gain is small. That is, even if the sprung gain is the same, a tendency that the degree of vibration suppression on the spring decreases due to the increase of the unsprung gain is recognized. That is, the electromagnetic absorber 20 generates a force that causes the sprung member 200 and the unsprung member 202 to approach and separate from each other. For example, a force in the same direction (for example, downward) is simultaneously applied to both members. It is considered that one reason is that the damping force cannot be individually applied to both members. When the damping force component with respect to the unsprung mass of the damping force of the electromagnetic absorber 20 increases, for example, the damping force with respect to the unsprung force is not affected by the damping force component with respect to the unsprung mass. It is presumed that the damping effect on the sprung is reduced due to the fact that the components are easily canceled out. FIG. 6 described above shows the relationship between the unsprung gain and the degree of vibration suppression of the unsprung member 202 when the sprung gain is small (Csa). The relationship between the sprung gain and the degree of vibration suppression of the unsprung member 202 when the sprung gain increases from Csa to Csb is the relationship between the above-mentioned sprung gain and the degree of vibration suppression of the sprung member 200. Similarly, even when the unsprung gain is the same, a tendency that the degree of vibration suppression under the spring decreases as the sprung gain increases.

  In this embodiment, when the unsprung gain is large, the sprung gain is increased in order to make the degree of vibration suppression of the sprung member 200 the same as when the unsprung gain is small (Csb> Cs). -min2> Csa). If the above phenomenon is interpreted in reverse, when the unsprung gain is decreased and the sprung gain is decreased, the degree of vibration suppression of the sprung member 200 is unlikely to decrease and the ride comfort is unlikely to deteriorate. It can be said that there is a tendency. In the present embodiment, the ratio Cs / Cg of the sprung gain Cs to the unsprung gain Cg is the case where the two gains are set to values with an emphasis on grounding when the two gains are set to values with an emphasis on reducing power consumption. (Csa / Cga> Csb / Cgb). For this reason, the ride comfort is easily maintained.

  Further, in this embodiment, the ride comfort is evaluated by the ratio (that is, the sprung transmission ratio) at which the vibration due to the road surface unevenness is transmitted to the sprung member 200, but the road surface condition is the same. It is. Therefore, even if the sprung transmission ratio is the same for the occupant, traveling on a good road is less comfortable on the spring than traveling on a bad road and is comfortable. Therefore, for example, in order to improve the riding comfort when traveling on a rough road, the sprung gain Cs can be made larger than Csb shown in the drawing to increase the degree of vibration suppression on the spring. For example, conversely, in order to increase the effect of reducing power consumption when traveling on a good road, there is room for lowering the degree of vibration on the spring by making the sprung gain Cs smaller than Csa shown in the figure.

  As can be understood from the above description, when the power consumption is reduced, the two gains Cs and Cg are determined to be values Csa and Cga in the power consumption reduction region. On the other hand, in order to improve the ground contact property when traveling on a rough road, the two gains Cs and Cg are increased and determined as Csb and Cgb.

3.3. About regeneration of electric power.
The electromagnetic absorber 20 includes the electromagnetic motor 24 (hereinafter may be abbreviated as “motor”) as described above, and a damping force is generated when electric power is supplied to the motor 24. Further, when the motor 24 is passively rotated in accordance with the approach / separation between the sprung member 200 and the unsprung member 202, the electromagnetic absorber 20 generates a damping force by generating power. If more electric power is generated than electric power supplied to the motor 24, a part of the generated electric power is stored in the battery 120. FIG. 10 schematically shows the relationship between the relative displacement speed ΔXv (= Xv2−Xv1) between the sprung member 200 and the unsprung member 202 and the approach / separation force Fv generated by the electromagnetic absorber 20. In this figure, the first and third quadrants are braking areas, and an approach / separation force Fv is generated in the direction of braking relative displacement. On the other hand, the second and fourth quadrants are acceleration regions, and an approach / separation force Fv is generated in the direction of accelerating relative displacement.

  A short-circuit characteristic line is shown in the first and third quadrants (braking region). The short-circuit characteristic line indicates the magnitude of the approach / separation force Fv generated when the phases of the motor 24 are short-circuited with each other. In the region sandwiched between the short-circuit characteristic line and the horizontal axis, the approach / separation force Fv is relatively small, the relative displacement speed ΔXv is relatively large, and the power generated by the electromagnetic absorber 20 is stored in the battery 120. It is an area. In this embodiment, by setting the sprung gain (Cs) and the unsprung gain (Cg) to the values Csa and Cga within the power consumption reduction region, the sprung member 200 and the unsprung member 202 approach and separate from each other. In this case, the possibility that the relative displacement speed ΔXv and the approach / separation force Fv become values in the regeneration region increases. That is, electric power is easily regenerated, and electric power generated by the electromagnetic absorber 20 is easily stored in the battery 120. In other words, in this embodiment, by setting the sprung gain and the unsprung gain to values within the power consumption reduction region, not only the amount of power supplied to the motor 24 is reduced, but also power is easily regenerated. As a result, power consumption can be effectively reduced.

3.4. Damping force control program.
FIG. 11 shows a flowchart of the damping force control program, and the control of the electromagnetic absorber 20 will be described in detail. This damping force control program determines the target value of the damping force generated by each of the four electromagnetic absorbers 20 and transmits a command to each inverter 130. Then, the damping force control program is repeatedly executed by the computer of the ECU 100 every extremely short time, and the function of the damping force control unit 150 of the ECU 100 described above is exhibited, so that each electromagnetic absorber 20 is individually controlled.

  In step 11 (hereinafter, step 11 is abbreviated as “S11”, and the same applies to other steps), the road surface state through which each wheel passes, the charged amount of the battery 120, the traveling state of the vehicle (turning state, acceleration) Deceleration state, etc.) is acquired. The road surface state is acquired based on the vertical acceleration Gg of each unsprung member 202 based on the detection value of each acceleration sensor 62 by the function of the road surface state determination unit 162 described above. In the present embodiment, the determination of the road surface condition is performed by executing a road surface condition determination program described later. The storage amount is determined based on the voltage E of the battery 120 detected by the voltmeter 122 by the function of the storage amount determination unit 164 described above. Specifically, when the voltage E is equal to or lower than the set voltage, it is determined that the charged amount is relatively small. When the voltage E exceeds the set voltage, it is determined that the charged amount is relatively large. The traveling state is acquired based on the lateral acceleration Gy based on the detection value of the lateral acceleration sensor 110 and the vehicle speed V based on the detection value of the vehicle speed sensor 112 by the function of the traveling state determination unit 166 described above. Specifically, for example, when the absolute value of the lateral acceleration Gy exceeds the set acceleration, it is determined that the vehicle is turning, and when the absolute value of the degree of change in the vehicle speed V exceeds the set value, the acceleration / deceleration state ( Acceleration state or deceleration state).

In S12, the displacement speeds Xv2 and Xv1 of the sprung member 200 and the unsprung member 202 are acquired for each wheel. These displacement velocities Xv2 and Xv1 are values obtained by integrating detection values of the vertical acceleration sensors 60 and 62 (detection values based on detection signals not passing through the bandpass filter 126 for the unsprung acceleration sensor 62), respectively. The In S <b> 13, “gain determination processing” is performed to determine the sprung gain (Cs) and the unsprung gain (Cg) for obtaining the damping force target value F of the electromagnetic absorber 20 corresponding to each wheel. In the gain determination process, two gains of each electromagnetic absorber 20 are determined as Csa, Cga or Csb, Cgb based on the road surface state, the storage amount, and the traveling state. Details of the gain determination process will be described later. In S14, the damping force target value F is determined by substituting the two determined gains and the displacement speeds Xv2 and Xv1 into Equation 1 for each of the electromagnetic absorbers 20 corresponding to the wheels. In S15, a power supply command is issued to each inverter 130 so that each electromagnetic absorber 20 generates an approaching / separating force corresponding to the damping force target value F. Note that the damping force target value F can be a value indicating the magnitude of the approaching / separating force itself. For example, the damping force target value F can be a value indicating the magnitude of the output torque of the motor 24, It is possible to make the value obtained by dividing the output torque by the set coefficient (that is, the value indicating the magnitude of the approaching / separating force and output torque by multiplying the damping force target value F by the set coefficient) It is.
Each inverter 130 that has received the power supply command determines a duty ratio according to the command, and supplies an appropriate amount of power to the motor 24 of each electromagnetic absorber 20, whereby the sprung member 200 and the unsprung member 202. The displacement of is suppressed. For example, when the two gains are increased (Csb, Cgb), the riding comfort and the ground contact performance during rough road driving are kept good. Further, the two gains are reduced according to the situation (Csa, Cga), and the power consumption of the electromagnetic absorber 20 is reduced by reducing the amount of supplied power and regenerating the power.

3.5. Gain determination process
FIG. 12 shows a flowchart of the “gain determination process” in S13. As described above, the gain determination process is a process of determining the gain of each electromagnetic absorber 20 based on the road surface state, the storage amount, and the traveling state. In the determination in S21, the determination is YES when the traveling state is at least one of the turning state and the acceleration / deceleration state, and in S22, the gains Cs and Cg of the electromagnetic absorber 20 corresponding to each of all the wheels are in contact with the ground. The important values Csb and Cgb are set. By setting the gain of all the electromagnetic absorbers 20 to a value that emphasizes grounding, each damping force target value F is determined so that the grounding of each wheel is kept good, and power is supplied (S14 described above) , S15). That is, “grounding priority control” which is damping force control that places importance on grounding is performed for all the electromagnetic absorbers 20. As a result, a stable grip force can be obtained when turning, acceleration, and deceleration (braking) are performed. In the present embodiment, the gain is determined such that the traveling state has priority over the road surface state and the amount of power storage. Various gains (Csa, Cga, Csb, Cgb) are stored in the storage unit 140, and the gains are determined by reading values corresponding to the stored various gains.

On the other hand, if the determination in S21 is NO, that is, the traveling state is a traveling state in which it can be regarded that the vehicle is traveling straight at a substantially constant speed (in other words, “the traveling state in which it is regarded that turning or acceleration / deceleration is not performed”). If the vehicle is in a certain steady straight state, in S23 and S24, based on the road surface condition acquired in S11, (i) all wheels are on a bad road, or (ii) some wheels are on a bad road. There are cases where the remaining wheels are on a good road, or (iii) all the wheels are on a good road. Further, in S25 and S26, cases are classified based on whether or not the amount of power stored in the battery 120 is relatively large based on the amount of power stored in S11. Then, the gain is determined as follows (a) to (e).
(a) When “all wheels are on a bad road and the amount of stored electricity is relatively large”, the gains Cs and Cg of all the electromagnetic absorbers 20 are changed to the values Csb and Cgb that emphasize grounding in S22. Is done. As a result, it is possible to improve the grounding property when traveling on a rough road. In this case, power consumption increases, but there is no particular problem because the amount of power stored in the battery 120 is relatively large.

(b) If “all wheels are on a bad road and the amount of stored electricity is relatively small”, the gains of the three electromagnetic absorbers 20 are set to values that emphasize grounding in S23, and the remaining The gain of one electromagnetic absorber 20 is set to values Csa and Cga that emphasize power saving. As a result, the grounding property when traveling on rough roads is good for the three wheels, and as a whole, good grounding property can be obtained in a steady straight traveling state. On the other hand, the damping force target value F of one electromagnetic absorber 20 becomes relatively small, and the supplied power is reduced and the power is easily regenerated (S14, S15). That is, with respect to the one electromagnetic absorber 20, “power saving control” which is damping force control that places importance on reducing power consumption is performed. Therefore, the power consumption of the one electromagnetic absorber 20 is reduced, and in some cases, the power is regenerated by the power generation of the one electromagnetic absorber 20. As shown in FIG. 10, the regeneration of electric power is performed when the relative displacement speed ΔXv and the damping force target value F (the approach / separation force Fv in the figure) are values within the above-described regeneration region. In the present embodiment, the gain that places importance on reducing power consumption is set so that the relative displacement speed ΔXv and the damping force target value F are likely to be values in the regeneration region, as described above. Further, when traveling on rough roads, the vibration of the unsprung member 202 becomes vigorous and the relative displacement speed ΔXv increases, so that it is considered that relatively regenerated electric power increases. As described above, the four electromagnetic absorbers 20 as a whole can ensure the grounding property when traveling on rough roads while suppressing an increase in power consumption.
In the present embodiment, the electromagnetic absorber 20 for which power-saving control is performed has a larger average value of the displacement speed Xv1 of the unsprung member 202 out of the two corresponding to the rear wheels. Further, in the state before the new gain is determined, when the grounding-oriented control is performed on one of the two electromagnetic absorbers 20 corresponding to the rear wheels and the power saving control is performed on the other, The state is made to continue.

  In the determination of the gain in the processing of S23, S25, S22, and S27, in S27, for the three electromagnetic absorbers 20 for which grounding-oriented control is performed, the gain is determined such that the road surface state is prioritized over the charged amount. For one electromagnetic absorber 20 to be subjected to power saving control, a gain is determined with priority given to the amount of stored power over the road surface condition. In the present embodiment, the grounding-oriented control is all performed at the time of turning. For example, even at the time of turning, power-saving control is performed on the electromagnetic absorber 20 on the rear side of the turning inner wheel with a relatively small burden. It is also possible to suppress an increase in power consumption.

  (c) When “some wheels are on a bad road and the remaining wheels are on a good road”, the charged amount of the battery 120 is not determined, and the electromagnetic absorber 20 corresponding to the wheel on the bad road is determined in S28. The gain of the electromagnetic absorber 20 corresponding to the wheel on the good road is set to a value focusing on power saving. As a result, the grounding property of the wheel on the bad road is maintained well, the power consumption of the electromagnetic absorber 20 corresponding to the wheel on the good road is reduced, and the decrease in the charged amount of the battery 120 is suppressed. The case where some wheels are on a bad road and the remaining wheels are on a good road corresponds to, for example, a case where a repair mark is left on one side of the road due to waterworks or the like. In the process of S28, the gain is determined for all the electromagnetic absorbers 20 based on the traveling state and the road surface state.

  (d) “When all wheels are on a good road and the amount of power stored in the battery 120 is relatively large”, in S29, the gain of one electromagnetic absorber 20 is set to a value that emphasizes grounding, and three The gain of the electromagnetic absorber 20 is set to a value that emphasizes power saving. As a result, even if the power is efficiently generated by the three electromagnetic absorbers 20 and the power is regenerated, the power is consumed by one electromagnetic absorber 20 and the battery 120 is prevented from being excessively charged. be able to. In addition, the electromagnetic absorber 20 to which the grounding emphasis control is performed has a larger average value of the displacement speed Xv1 of the unsprung member 202 out of the two corresponding to the front wheels. In addition, in the state before the new gain is determined, if one of the two electromagnetic absorbers 20 corresponding to the front wheels is subjected to grounding-oriented control and the other is power-saving control, the state continues. Is done.

(e) When “all wheels are on a good road and the amount of power stored in the battery 120 is relatively small”, the gains of all the electromagnetic absorbers 20 are set to values that emphasize power saving in S30. As a result, the power consumption is effectively reduced, and in some cases, the power is regenerated by the power generation of the electromagnetic absorber 20, the decrease in the amount of electricity stored in the battery 120 is suppressed, or the amount of electricity stored in the battery 120 can be increased. it can.
In determining the gain in the processing of S24, S26, S29, and S30, in S29, for one electromagnetic absorber 20 for which grounding emphasis control is performed, the gain is determined such that the storage amount is prioritized over the road surface condition. For the three electromagnetic absorbers 20 for which power control is performed, the gain is determined such that the road surface state is given priority over the amount of power storage.

As described above, an appropriate gain is determined by the gain determination process in accordance with the traveling state, the road surface state, and the storage amount. As a result, it is possible to effectively reduce the power consumption according to the situation, such as reducing the power consumption when driving on a good road while maintaining a relatively good grounding property when driving on a rough road.
Note that it is not an essential condition to perform grounding-oriented control in at least one of the turning state and the acceleration / deceleration state, for example, in at least one state of the turning state and the acceleration / deceleration state, It is possible to perform grounding-oriented control for some of the electromagnetic absorbers 20 and perform power saving control for the remaining electromagnetic absorbers 20.

  In this embodiment, the grounding emphasis control that determines the damping force target value by setting the sprung gain Cs and the unsprung gain Cg to values Csb and Cgb emphasizing grounding corresponds to the “first control”, and two gains are set. The power saving control in which the damping force target value F is determined using the power saving priority values Csa and Cga corresponds to the “second control”. Further, the unsprung gain value Cg-max at the boundary between the power consumption reduction region and the grounding importance region corresponds to the “set value”, and the grounding value Cgb of the unsprung gain of the first control is smaller than the setting value. Largely, the value Cga of the second control unsprung gain emphasizing power saving is set below the set value. When the maximum value of the power consumption reduction region and the minimum value of the grounding-oriented region are different, for example, any one of them can be set as a “set value”. Further, for example, as shown in FIG. 14, the unsprung gain in the first control is made larger than the minimum value (Cg-min) in the grounding-oriented region, and the unsprung gain in the second control is set to the maximum in the power consumption reduction region. The value (Cg-max) or less can also be set. Furthermore, in the present embodiment, switching between damping gain control, that is, “first control and second control” is performed by switching between two gains, which are grounding-oriented values or power-saving-oriented values. Is switched.

3.6. Road surface condition judgment program
FIG. 13 shows a flowchart of a “road surface state determination program” for determining whether the road surface state is good or not, that is, whether the running road is a good road or a bad road. The road surface state determination program is repeatedly executed every extremely short time by the computer of the ECU 100, whereby the function of the road surface state determination unit 162 is exhibited and the road surface state is determined. This road surface condition determination program corresponds to one of the four wheels, and the four road surface condition determination programs are executed in parallel by the time division process, so that the state of the road surface through which each wheel passes is determined. To be acquired. Since the four road surface condition determination programs are similar to each other, only one program will be described representatively. Further, the four road surface condition determination programs are executed in parallel with the damping force control program by time division processing.

  In S41, the vibration acceleration (G-10 Hz) in the 10 Hz region of the unsprung member 202 is acquired. The vibration acceleration in the 10 Hz region is acquired based on the detection signal of the unsprung acceleration sensor 62 after passing through the bandpass filter 126. In S42, it is determined whether power saving control is being performed. This is because the magnitude of the unsprung gain (Cg) differs between the power saving control and the grounding-oriented control, and therefore the magnitude of vibration acceleration of the unsprung member 202 is different even if the road surface condition is the same. is there. When power saving control is performed, the unsprung gain (Cg) is small and the vibration acceleration of the unsprung member 202 is relatively large. Therefore, in S43, the threshold acceleration for determining a bad road is relatively large. (Threshold acceleration = G−high). On the contrary, when the grounding-oriented control is performed, the threshold acceleration is made relatively small in S44 (threshold acceleration = G-low). When the absolute value of the vibration acceleration of the unsprung member 202 is larger than the threshold acceleration, 1 is added to the counter C (S45, S46), and when the absolute value is less than the threshold acceleration, it is not added. Thereafter, 1 is added to the counter N (S47).

  When the processes of S41 to S47 described above are repeated N1 times, the determination of S48 is NO and the processes of S49 and subsequent steps are executed. In S49, the values of the variables C1, C2, and C3 for storing the value of the counter C are updated, the sum Csum of these variables C1, C2, and C3 is obtained, and the counters C and N are reset to 0. . In the variables C1, C2, and C3, newer values are stored as the numbers are smaller. In this embodiment, the value of the counter C is stored in order to shorten the interval for determining the road surface condition by decreasing the value of the set number N1. Specifically, for example, if data for A times is required to determine the road surface state, the set number N1 is A when the counter C is not stored, but the set number of times is stored by storing the counter C. N1 can be reduced to about one third of A. Therefore, the road surface condition determination result can be updated at shorter time intervals.

  In the determination of S50, when the total sum Csum is larger than the set number C0, it is determined that the vibration acceleration of the unsprung member 202 is increased by the road surface input, that is, the road surface state during traveling is a bad road. The flag Rx indicating the road surface state is turned ON. On the other hand, when the total sum Csum is equal to or less than the set number C0, it is determined that the road surface state is a good road, and the flag Rx indicating the road surface state is turned OFF. The flag Rx indicating the road surface state is referred to in the process of S11 of the aforementioned “damping force control program (FIG. 11)”, and is used in the determination processes of S23 and S24 in the “gain determination process (FIG. 12)”. Note that a number (1 to 4) indicating which electromagnetic absorber 20 corresponds is input to “x” of the flag Rx. That is, in the process of S11, the flag Rx (R1 to R4) indicating each road surface state of the four road surface state determination programs is referred to, and the road surface state for each wheel is acquired.

  In the present embodiment, the road surface condition is simply determined in two stages, that is, a bad road or a good road, but the road surface condition can also be determined in three or more stages. Further, the power storage state and the running state can be determined in three or more stages. For example, when the road surface condition is determined in three or more stages and traveling on a road surface intermediate between a good road and a bad road, the grounding-oriented control is performed for the two wheels, and the power saving control is performed for the remaining two wheels. It is also possible to do it. In addition, for example, when the traveling state is determined in three or more stages and the vehicle is traveling on a good road and when sudden turning / acceleration / deceleration is not performed, power saving control can be performed on one or more electromagnetic absorbers 20. .

  In the present embodiment, the two gains are set to Csb and Cgb for grounding values and Csa and Cga for power saving. However, the vibrations of the sprung member 200 and the unsprung member 202 have been set. The number can be increased or decreased according to the intensity, running state, road surface state, power storage state, and the like. For example, when the vibration of the sprung member 200 is relatively intense, the sprung gain is set to a value larger than Csa and Csb, and when the vibration of the unsprung member 202 is relatively intense, the unsprung gain is determined from Cga and Cgb. Can also be large. In addition, for example, when the power storage state is low, at least one of the two gains can be reduced. When the unsprung gain is made smaller than Cgb when traveling on rough roads, the unsprung gain may be a value within the ground contact importance range (Cg> Cg-max) and smaller than Cgb. desirable. Furthermore, for example, when driving on a rough road and in a turning state, the unsprung gain can be made larger than Cgb. Furthermore, for example, the road surface state and the traveling state can be discriminated in three or more stages, and the two gain values can be increased or decreased depending on the intensity of vibration input from the road surface or the intensity of turning / acceleration / deceleration. it can.

  In the present embodiment, the gain is determined based on all of the road surface state, the charged amount, and the traveling state. However, the gain can be determined based on any one or two of them. However, since ground contact-oriented control is suitable for rough road travel and power saving control is not suitable for rough road travel, it is desirable to perform control based on at least the road surface condition. In the present embodiment, the two gains are set to Csa and Cga at the time of power saving control. However, by giving a command to stop the power supply to the inverter 120, the power supply amount is reduced to zero. Electric power can be easily regenerated and power consumption can be effectively reduced.

  In this embodiment, the suspension device 10 is provided with the compression coil spring 16 that is one mode of the “spring”. However, instead of the compression coil spring 16 or together with the compression coil spring 16, the suspension device 10 has a “spring”. It is also possible to provide an air spring that is an aspect of the above. The air spring is, for example, a gas chamber that generates an elastic force in a direction that causes the sprung member 200 and the unsprung member 202 to be separated by reducing the volume in accordance with the approach between the sprung member 200 and the unsprung member 202. For example, it can be provided with an air chamber. The electromagnetic motor 24 is a brushless motor, but may be a brush motor, for example. The electromagnetic motor 24 includes a permanent magnet and an electromagnet that generates a magnetic force when power is supplied. The electromagnet includes, for example, a coil and a core (for example, an iron core) around which the coil is wound. Or having a coil but no core.

In the present embodiment, the force generated by the electromagnetic absorber 20 includes a damping force component. However, in addition to the damping force component, a force for suppressing vibration can be generated based on the amount of displacement. In that case, for example, a term obtained by multiplying the displacement amount X2 of the sprung member 200 by the gain Ks and a term obtained by multiplying the displacement amount X1 of the unsprung member 202 by the gain Kg are added to the right side of [Expression 1]. be able to.
[Formula 4] F = Cs.Xv2-Cg.Xv1 + Ks.X2-Kg.X1
Note that the smaller the values of the gains Ks and Kg, the higher the effect of reducing power consumption. Therefore, the gains Ks and Kg can be made relatively large when performing grounding-oriented control, and the gains Ks and Kg can be made relatively small (or set to 0) when performing power saving control.

It is a figure which shows the suspension apparatus with which the suspension system which is an Example of claimable invention was equipped. It is a figure which shows typically the control apparatus (electronic control unit: ECU) which controls the electromagnetic absorber of the said suspension apparatus. It is a schematic diagram which shows the inverter which supplies electric power to the said electromagnetic absorber. It is the schematic diagram which represented a part of vehicles provided with the said suspension apparatus with the 2 degree-of-freedom model containing a sprung member and an unsprung member. It is a schematic diagram which shows the relationship between the unsprung gain for determining the damping force target value of the said electromagnetic absorber, and electric power consumption. It is a schematic diagram which shows the relationship between the said unsprung gain and a grounding load fluctuation rate. It is a schematic diagram which shows the relationship between the sprung gain for determining the damping force target value of the said electromagnetic absorber, and electric power consumption. It is a schematic diagram which shows the relationship between the sprung gain and the sprung mass damping degree (riding comfort) when the unsprung gain is small. It is a schematic diagram which shows the relationship between the sprung gain and the sprung mass damping degree when the unsprung gain is large. It is a schematic diagram which shows a regeneration area | region in the relationship between the relative displacement speed of the said sprung member and an unsprung member, and approach / separation force. It is a figure which shows the flowchart of the damping force control program performed by the said control apparatus. It is a figure which shows the flowchart of the gain determination process performed by the said control apparatus. It is a figure which shows the flowchart of the road surface state determination program performed by the said control apparatus. It is a schematic diagram which shows another relationship between the said unsprung gain and the unsprung damping degree (grounding property).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Suspension apparatus 20: Electromagnetic absorber 22: Cylinder 24: Electromagnetic motor 36: A part of vehicle body 60: Sprung acceleration sensor 62: Unsprung acceleration sensor 100: Electronic control unit [ECU] (control apparatus) 120: Battery ( 122): Voltmeter 130: Inverter 140: Storage unit 150: Damping force control unit 152: Gain determination unit 160: Reference information acquisition unit 162: Road surface state determination unit 164: Charge amount determination unit 166: Travel state determination unit 200: Sprung member 202: Unsprung member

Claims (5)

A spring for generating a force for separating the sprung member and the unsprung member, and an electromagnetic absorber for generating a force for approaching and separating the sprung member and the unsprung member together with the spring. A suspension device;
The electromagnetic absorber generates a force including a sprung damping force component that is a damping force component based on the displacement speed of the sprung member and an unsprung damping force component that is a damping force component based on the displacement speed of the unsprung member. And a suspension system comprising a control device for controlling the electromagnetic absorber,
The control device is
The electromagnetic absorber is controlled between a first control in which the gain of the unsprung damping force component is greater than a set value and a second control in which the gain of the unsprung damping force component is less than or equal to the set value. Suspension system characterized by being configured to switch at The control device is
The control of the electromagnetic absorber according to claim 1, wherein the control of the electromagnetic absorber is switched based on at least one of a road surface state, a storage state of a battery that is a power source of the electromagnetic absorber, and a traveling state of the vehicle. Suspension system. The control device is
In the second control, the gain of the sprung damping force component is made smaller than the value in the first control, and the ratio of the gain of the sprung damping force component to the gain of the unsprung damping force component is set to the first control. The suspension system according to claim 1, wherein the suspension system is configured to be larger than the ratio in one control. The control device is
In the second control, each value of the gain of the sprung damping force component and the gain of the unsprung damping force component is set to a value suitable for power regeneration by the electromagnetic absorber. The suspension system according to any one of claims 1 to 3. The suspension system includes the suspension device corresponding to each of a plurality of unsprung members,
The control device is
The suspension according to any one of claims 1 to 4, wherein the control of the electromagnetic absorber of each of the plurality of suspension apparatuses is individually switched between the first control and the second control. system.

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