JP4894501B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a suspension system including an electromagnetic actuator that generates a force for moving a vehicle body and a wheel toward and away from each other in the vertical direction.

In recent years, as a suspension system for a vehicle, a so-called electromagnetic suspension system including an electromagnetic actuator that generates a force for moving a vehicle body and a wheel in a vertical direction to approach and separate has been studied. There are suspension systems described in the literature. 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.
JP 2006-117210 A JP 2003-42224 A

  The electromagnetic actuator can also function as a shock absorber for damping vibration, and is always operated during traveling. Therefore, the power consumption of the system by the electromagnetic actuator is a serious problem of the electromagnetic suspension system. In the system described in Patent Document 2, when the average power consumption within a certain time is larger than the set upper limit value, the supply current is reduced to suppress the power consumption, thereby addressing the above problem. is doing. Thus, the practicality of the suspension system including the electromagnetic actuator can be improved by reducing the power consumption of the electromagnetic actuator by some countermeasure. 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 actuator.

In order to solve the above-described problem, the vehicle suspension system according to the present invention provides a vehicle body in a state where the electromagnetic actuator does not generate an actuator force in the control for changing the distance between the vehicle body wheels for the purpose of changing the vehicle height. The vehicle body wheel distance, which is different from the reference distance, which is the distance between the wheels, is maintained by supplying power to the electromagnetic actuator and generating the actuator force. When changing the distance between wheels, it is possible to execute control to generate the actuator force as a braking force of a specific magnitude based on the electromotive force generated in the electric motor for the relative movement between the vehicle body and the wheel at that time It is structured.

  Since the suspension system of the present invention does not supply electric power to the electric motor when changing the distance between the vehicle body wheels toward the reference distance, it is possible to reduce power consumption by the actuator. Therefore, according to the present invention, power consumption of the system is suppressed, and a highly practical suspension system is constructed.

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 each of the following items, the items (1) and (5) are combined and further features are equivalent to claim 1, and each of items (7) and (8) is claim 2. , Claim 3, claim 1 to claim 3, which are limited by the technical features of (10) and (11). Claim 4 is limited by the technical features of the items (10) and (12) in claim 5, and in any one of claims 1 to 5 in claims (13) and (15). Claims 6 to which limitations are imposed by the technical features respectively correspond to Claim 6 respectively.

(1) a suspension spring that elastically supports a sprung member that forms part of the vehicle body and an unsprung member that holds the wheel;
An electromagnetic actuator that is provided in parallel with the suspension spring and has an electric motor as a power source, and generates an actuator force that is a force for approaching and separating the vehicle body and the wheel in the vertical direction;
A vehicle suspension system comprising a control device for controlling the operation of the electromagnetic actuator,
The control device can execute distance change control for changing the distance between the vehicle body and the wheel, which is the distance between the vehicle body and the wheel in the vertical direction. In the distance change control, the electromagnetic actuator does not generate an actuator force. When changing the distance between the vehicle body wheels toward the reference distance, which is the distance between the vehicle body wheels in the state, the actuator force of the electromagnetic actuator is changed to the electromotive force generated in the electric motor with respect to the relative movement between the vehicle body and the wheels. A suspension system for a vehicle that executes specific braking force generation control that is generated as a braking force having a specific magnitude that is relied upon.

  In the distance change control, when the distance between the vehicle body wheels is changed to the target vehicle body wheel distance by the actuator, the distance is reached to the target against the elastic force of the suspension spring. Therefore, the amount of loss of the balance between the elastic force of the suspension spring and the shared load (the weight of the vehicle body shared by one wheel, which can be considered as the sprung weight) at the time when the target is reached. Maintains the distance by generating an actuator force. When changing the distance between the vehicle body wheels toward the reference distance, the distance between the vehicle body wheels is changed toward the reference distance by utilizing the loss of balance between the elastic force of the suspension spring and the shared load. It is possible to operate as follows. In the aspect described in this section, the electric motor functions as a generator at that time, and the actuator force is generated as a braking force having a specific magnitude depending on the electromotive force generated in the electric motor. In other words, according to the aspect of this section, when changing the distance between the vehicle body wheels toward the reference distance, it is not necessary to supply power from the power source to the electric motor. It becomes possible to suppress consumption. Note that the “specific braking force generation control” in the aspect of this section includes, for example, control that generates an actuator force as a fixed braking force, and the actuator force according to the fluctuation speed of the distance between vehicle wheels. It is possible to employ control that is generated as a braking force having a specific magnitude. In addition, “when changing the distance between the vehicle wheels toward the reference distance” in this section means that the direction in which the distance between the vehicle wheels is changed is limited. It is not meant to be limiting.

  As the “suspension spring” in the aspect of this section, for example, various springs such as a coil spring and a fluid spring that elastically supports the vehicle body and the wheel by fluid pressure can be adopted.

  The specific structure of the “electromagnetic actuator” in the aspect of this section is not limited, and the function is not particularly limited. For example, for the purpose of suppressing the roll, pitch, etc. of the vehicle body It is possible to adopt one that has a function to control the posture of the robot, a function as a shock absorber, and the like. The “electric motor” in this section may be a motor that performs an operation suitable for the structure of the actuator, and may be, for example, a rotary motor or a linear motor.

  (2) The electromagnetic actuator includes: (a) a male screw portion that is not movable relative to one of the sprung member and the unsprung member; and (b) the sprung member and the sprung member. And a female screw portion that rotates relative to the male screw portion as the vehicle body and the wheel approach and separate from each other, and is screwed into the male screw portion, and is rotated by the electric motor. The vehicle suspension system according to item (1), wherein the actuator force is generated by applying a relative rotational force to the male screw portion and the female screw portion.

  The aspect described in this section is an aspect in which the electromagnetic actuator is limited to a so-called screw mechanism. If the screw mechanism is employed, the electromagnetic actuator can be easily configured. In addition, in the aspect of this term, it is arbitrary which male screw part is provided on either the sprung member side or the unsprung member side, and which is provided with the female screw part. Furthermore, the male screw portion may be configured to be non-rotatable and the female screw portion may be configured to rotate. Conversely, the female screw unit may be configured to be non-rotatable and the male screw unit configured to be rotatable.

  (3) The vehicle suspension system according to (1) or (2), wherein the electric motor is a brushless DC motor.

  A brushless DC motor is suitable as a drive source for an electromagnetic actuator because of its good controllability.

(4) The controller is
Any of (1) to (3), comprising a plurality of switching elements corresponding to each phase of the electric motor, and a drive circuit for controlling and driving the electric motor by operation control of the plurality of switching elements. The vehicle suspension system described in 1.

  For example, an inverter or the like can be employed for the “drive circuit” described in this section. According to the aspect of this section, the control drive of the electric motor is easily and accurately performed by the operation control of the switching element such as the change of the combination of the ON / OFF state of the switching element such as the FET provided for each phase. be able to.

  (5) The control device according to any one of (1) to (4), wherein the control device is capable of executing a damping force control that generates an actuator force of the electromagnetic actuator as a damping force against at least sprung vibration. Vehicle suspension system.

  For the “damping force control” in the aspect of this section, it is possible to employ a control based on a so-called skyhook theory that generates a damping force for only the sprung vibration. In addition, a control system that generates damping force for sprung and unsprung vibrations or damping force for sprung and unsprung relative vibrations to make the actuator function as a shock absorber (also called “damper”) is adopted. It is also possible to do.

  (6) Carrying out vehicle body posture control in which the control device generates the actuator force of the electromagnetic actuator as at least one of a roll restraining force for restraining the roll of the vehicle body and a pitch restraining force for restraining the pitch. The vehicle suspension system according to any one of (1) to (5), which is made possible.

  The aspect of this term is an aspect which makes it possible to suppress the inclination of the vehicle body which occurs when the vehicle turns, for example, when the vehicle accelerates or decelerates, by the actuator. According to the aspect of this section, active posture control of the vehicle body can be executed in accordance with, for example, the vehicle speed, the steering angle, the lateral acceleration generated in the vehicle body, the longitudinal acceleration, and the like.

  (7) The specific braking force generation control is control that is executed by generating the actuator force of the electromagnetic actuator as a braking force having a specific magnitude according to the fluctuation speed of the distance between the vehicle body wheels (1) The vehicle suspension system according to any one of items 1 to (6).

  In general, whether the electric motor is in a state where it receives power from a power source and generates a force or whether the electric motor is in a state where it generates power while generating power depends on the operating speed of the electric motor and the force of the electric motor. That is, it is determined by the relationship between the fluctuation speed of the distance between the vehicle body wheels and the actuator force. Therefore, according to the aspect described in this section, the actuator force can be generated as a braking force having an appropriate magnitude. In addition, the aspect of this term can be an aspect in which, for example, an actuator force with a fixed damping coefficient that is a ratio between the operating speed of the electric motor and the force of the electric motor is generated.

  (8) The vehicle suspension according to any one of (1) to (7), wherein the specific braking force generation control is executed by conducting between the energization terminals of each phase of the electric motor. system.

  The mode described in this section may be conducted by causing some resistance to exist between the energization terminals of each phase of the electric motor, and is conducted by short-circuiting between the energization terminals. Also good. According to the aspect of this section, it is possible to reduce the power consumption of the system by setting the power consumption in the specific braking force generation control to 0 by relatively simple control. In addition, when the control device is provided with a drive circuit having a plurality of switching elements, it can be realized by setting the ON / OFF state of each phase switching element to a fixed state as described later. It is. Incidentally, the braking force obtained when the current-carrying terminals of each phase are conducted has a magnitude corresponding to the fluctuation speed of the distance between the vehicle body wheels. That is, the aspect of this section can be considered as one aspect of an aspect in which the actuator force is generated as a braking force having a specific magnitude corresponding to the fluctuation speed of the distance between the vehicle body wheels.

  (9) The vehicle suspension system according to item (8), wherein the specific braking force generation control is executed by short-circuiting energization terminals of each phase of the electric motor.

  The mode described in this section is a mode limited to a mode in which the current-carrying terminals are short-circuited in the mode in which the current-carrying terminals are conducted. According to the aspect of this section, it is possible to generate a large braking force among the braking forces depending on the electromotive force.

  (10) The specific braking force generation control is a control executed while regenerating the generated power that depends on the electromotive force generated in the electric motor to a power source that supplies the electric motor with power. The suspension system for a vehicle according to any one of items 1).

  The mode of this section is a particularly effective mode from the viewpoint of power saving of the system because the charge amount of the power source can be increased by the specific braking force generation control.

  (11) The vehicle control apparatus according to (10), wherein the specific braking force generation control is executed by generating the actuator force of the electromagnetic actuator as a braking force that maximizes the amount of electric power regenerated. Suspension system.

  (12) The specific braking force generation control causes the actuator force of the electromagnetic actuator to be generated as a braking force that is ½ of a braking force that is obtained when a current-carrying terminal of each phase of the electric motor is short-circuited. The vehicle suspension system according to item (10) or (11), wherein

  If the actuator force is generated as a braking force having a specified magnitude as in the latter mode, the amount of electric power regenerated can be maximized. That is, the latter aspect can be considered as one aspect of the former aspect. According to the aspects described in the above two items, it is possible to efficiently regenerate power.

(13) The vehicle suspension system includes a plurality of suspension springs, each of which is the suspension spring, and a plurality of electromagnetic actuators, each of which is the electromagnetic actuator, corresponding to a plurality of wheels of the vehicle. ,
The control device controls the operation of the plurality of electromagnetic actuators, and changes the vehicle height of the vehicle by executing the distance change control for each of the plurality of electromagnetic actuators. Vehicle height change control that can be executed, and in the vehicle height change control, when the distance between the vehicle body wheels for each of the plurality of wheels is changed toward the reference distance, the plurality of electromagnetic actuators The vehicle suspension system according to any one of (1) to (12), wherein the specific braking force generation control is executed for each.

  The aspect described in this section is an aspect in which suspension springs and electromagnetic actuators are disposed corresponding to a plurality of wheels, and the vehicle height of the vehicle can be changed using the plurality of electromagnetic actuators. Each electromagnetic actuator can employ the above-described aspects.

  (14) The vehicle height change control is a control that does not cause the vehicle body to be inclined more than a preset level when the vehicle body wheel distance for each of the plurality of wheels is changed toward the reference distance. The vehicle suspension system according to item 13).

  When the vehicle body wheel distance for each of the plurality of wheels is changed toward the reference distance, when specific braking force generation control is executed for each of the plurality of actuators, for example, one of the actuators If the fluctuation speed of the distance between the vehicle body wheels for the actuator of this part is faster than the fluctuation speed of the other actuators, the vehicle body may be inclined. According to the aspect described in this section, when changing the vehicle height, the vehicle body is controlled so as not to be inclined, so that it is possible to prevent the passenger from feeling uncomfortable. The aspect of this section may employ a control in which each of the plurality of electromagnetic actuators is not preceded by more than the set level with respect to the other, and the set level or more is not exceeded. Control may be employed to prevent delays. Further, in the aspect of this section, the control for adjusting the distance between the vehicle body wheels for each of the plurality of wheels, or the control for adjusting the fluctuation speed of the distance between the vehicle body wheels for each of the plurality of wheels. Etc. can be adopted.

(15) The specific braking force generation control with respect to each of the plurality of electromagnetic actuators causes the actuator force of each of the plurality of electromagnetic actuators to have a braking force having a specific magnitude according to a fluctuation speed of a distance between vehicle body wheels. As a control that is generated and executed as
When the control device changes the distance between the vehicle body wheels for each of the plurality of wheels toward the reference distance, when the vehicle body is tilted more than a set level, among the plurality of electromagnetic actuators The specific braking force generation control for any one or more of which is a part of the vehicle is prohibited, and for each of the one or more, the respective actuator force is used to suppress the inclination of the vehicle body. The vehicle suspension system according to (13) or (14), wherein the inclination suppression control generated as force is executed.

  The mode described in this section is a mode in which the control that does not cause the tilt of the vehicle body is specifically limited. According to the aspect of this section, since the specific braking force generation control is executed for at least some of the plurality of actuators, it is possible to suppress the leaning of the vehicle body and the power consumption of the system. Is possible.

  Hereinafter, embodiments of the claimable invention and modifications thereof will 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 [Mode of Invention]. can do.

≪Configuration and function of suspension system≫
The vehicle suspension system according to the first embodiment is a suspension system mounted on a vehicle having a relatively high vehicle height such as SUV. FIG. 1 schematically shows the suspension system 10 according to the first embodiment. 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 connects a suspension lower arm 22 as an unsprung member for holding the wheel 12 and a mount portion 24 as a sprung member provided on the vehicle body. 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 portion 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. And a mechanism and an electric motor 54 (a three-phase brushless DC motor, hereinafter simply referred to as “motor 54”) as a power source. 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.

  Due to the above-described structure, when the vehicle body and the wheel 12 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 can apply rotational torque to the screw rod 50, and with this rotational torque, it is possible to generate a resistance force that prevents the approach and separation between the vehicle body and the wheel 12. Has been. The actuator 26 functions as a so-called absorber (also referred to as “damper”) by causing this resistance force to act as a damping force against the approach and separation between the vehicle body and the wheel 12. In other words, the actuator 26 has a function of applying a damping force to the relative movement between the vehicle body and the wheel 12 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 with respect to the relative movement between the vehicle body and the wheel 12. With this function, it is possible to execute skyhook control in which a damping force proportional to the sprung absolute speed is applied. Further, the actuator 26 positively changes the distance between the vehicle body and the wheel in the vertical direction (hereinafter sometimes referred to as “vehicle-wheel-wheel distance”) by the actuator force, and the vehicle-wheel distance is set to a predetermined distance. It also has a function to maintain. 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.

  An annular buffer rubber 77 is attached to the inner wall surface of the upper end of the outer tube 30, and a buffer rubber 78 is also attached to the inner bottom wall surface of the outer tube 30. When the vehicle body and the wheel 12 approach / separate, when the key 40 moves relative to some extent in a direction in which the vehicle body and the wheel 12 are separated (hereinafter, may be referred to as “rebound direction”), the key 40 is interposed via the buffer rubber 77. In contrast, when the vehicle body and the wheel 12 are relatively moved in a direction in which the vehicle body and the wheel 12 approach each other (hereinafter, may be referred to as a “bound direction”), the lower end of the screw rod 50 is the buffer rubber 78. It contacts with the inner bottom wall surface of the outer tube 30 via. That is, the spring absorber assembly 20 has stoppers (so-called bound stoppers and rebound stoppers) against the approach and separation between the vehicle body and the wheels 12.

  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. FIG. 3 shows a schematic diagram of the air supply / discharge device 80. The air supply / discharge device 80 includes a compressor 82 that supplies compressed air to the pressure chamber 44. The compressor 82 includes a pump 84 and a pump motor 86 that drives the pump 84. The pump 84 sucks air from the atmosphere through the filter 88 and the check valve 90, pressurizes the air, and performs a check. It discharges through the valve 92. The compressor 82 is connected to the pressure chambers 44 of the four air springs 28 via the individual control valve device 100. The individual control valve device 100 includes four individual control valves 102 which are provided corresponding to the pressure chambers 44 of the air springs 28 and are normally closed valves, and open and close the flow paths for the pressure chambers 44. It is. The compressor 82 and the individual control valve device 100 are common to each other via a dryer 104 that removes moisture from the compressed air, and a flow restriction device 110 in which a throttle 106 and a check valve 108 are provided in parallel with each other. They are connected by a passage 112. The common passage 112 branches from between the compressor 82 and the dryer 104, and an exhaust control valve 114 for exhausting air from the pressure chamber 44 is provided at the branching portion.

  Due to the above structure, the suspension system 10 can adjust the air amount in the pressure chamber 44 of each air spring 28 by the air supply / discharge device 80, and each air spring can be adjusted by adjusting the air amount. It is possible to change the distance between the vehicle body wheels for each wheel 12 by changing the spring length of 28. Specifically, it is possible to increase the distance between the vehicle body wheels by increasing the amount of air in the pressure chamber 44, and to decrease the distance between the vehicle body wheels by decreasing the amount of air.

  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 a battery 150 as a power supply source via a converter 148, and each control valve 102, pump motor 86, etc., and motor of each actuator 26 that the air supply / discharge device 80 has. 54 is supplied with power from 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, and the force of the motor 54 becomes a force corresponding to the amount of supplied current.

The vehicle includes an ignition switch [I / G] 160, a vehicle speed sensor [v] 162 for detecting a vehicle traveling speed (hereinafter sometimes abbreviated as “vehicle speed”), and a vehicle body wheel distance for each wheel 12. Four stroke sensors [St] 164 to be detected, a vehicle height change switch [HSw] 166 operated by the driver for a vehicle height change instruction, and an operation angle sensor [δ] 170 for detecting the operation angle of the steering wheel , A longitudinal acceleration sensor [Gx] 172 that detects actual longitudinal acceleration that is the longitudinal acceleration actually generated in the vehicle body, a lateral acceleration sensor [Gy] 174 that detects actual lateral acceleration that is the lateral acceleration actually generated in the vehicle body, four vertical acceleration sensors [Gz _U] 176 for detecting a longitudinal acceleration of the vehicle body of each mounting portion 24 corresponding to the wheel 12 (vertical acceleration), each wheel 12 Four vertical acceleration sensor for detecting acceleration [Gz _L] 178, a throttle sensor [Sr] 180 for detecting an accelerator opening of the throttle, the brake pressure sensor [Br] 182 for detecting a master cylinder pressure of the brake, rotation of the motor 54 A resolver [θ] 184 that is a rotation angle sensor for detecting an angle, a charge amount sensor [E] 186 for detecting the charge amount of the battery 150, and the like are 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.

  A ROM included in the computer of the controller 142 stores a program for determining a target vehicle height, a program for controlling the actuator 26, a program for controlling the air spring 28, various data, and the like, which will be described later. In the suspension system 10, the set vehicle height that can be selected by the driver is set standard vehicle height (N vehicle height), set vehicle height higher than the set standard vehicle height (Hi vehicle height), and set standard vehicle height. Three low set low vehicle heights (Low vehicle height) are set, and the vehicle height is selectively changed to a desired set vehicle height by the driver's operation of the vehicle height change switch 166. The vehicle height change switch 166 issues a command for shifting the set vehicle height to a higher set vehicle height or a lower set vehicle height, that is, a vehicle height increase command or a vehicle height decrease command. It is structured.

≪Configuration of inverter etc.≫
As shown in FIG. 4, the motor 54 of each actuator 26 is a three-phase brushless motor in which coils are star-connected (Y-connected), and is driven by the inverter 146 as described above. The inverter 146 is a general one as shown in FIG. 4, and corresponds to each of the high side (high potential side) and the low side (low potential side) and is a U phase that is 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. The controller 142 of the ECU 140 determines a motor rotation angle (electrical angle) by a resolver 184 provided in the motor, 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. To be controlled. The inverter 146 is configured to energize the motor 54 by PWM (Pulse Width Modulation) control, and the controller 142 changes the ratio (duty ratio) between the pulse-on time and the pulse-off time. 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 amount of energized current and increases the rotational torque generated by the motor 54. Conversely, decreasing the duty ratio decreases the amount of energized current. 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 relative movement between the wheel and the vehicle body, The force generated by 54 does not necessarily depend on the power supplied from the power source. More specifically, when the motor 54 is rotated by an external force, an electromotive force is generated in the motor 54. When the motor 54 generates a motor force based on the electromotive force, that is, the actuator 26 generates an electromotive force. In some cases, an actuator force based on the above is generated.

  FIG. 5 conceptually shows the relationship between the rotational speed ω of the motor 54 and the rotational torque generated by the motor 54. Region (a) in this figure is a region where the direction of rotation torque of motor 54 is the same as the direction of rotation, and region (b) and region (c) are the direction of rotation torque of motor 54 and the direction of rotation. This is the opposite area. A line that divides the region (b) and the region (c) is a characteristic line when the current-carrying terminals of each phase of the motor 54 are short-circuited, that is, the rotation speed of the motor 54 obtained when so-called short-circuit braking is performed. It is a short circuit characteristic line which shows the relationship between (omega) and rotational torque. The region (c) in which the rotational torque generated by the motor 54 with respect to the rotational speed ω is smaller than the rotational torque on the short-circuit characteristic line is such that the motor 54 functions as a generator, and the motor 54 depends on the electromotive force to generate braking force. This is a region for generating rotational torque. Incidentally, the region (b) is a region in which the motor 54 receives a supply of electric power from the battery 150 and generates a torque that serves as a braking force, that is, a so-called reverse braking region. This is a region where the supply of torque is generated.

  Note that the inverter 146 has a structure that can regenerate the power generated by the electromotive force in the battery 150. In other words, when the relationship between the rotational speed ω of the motor 54 and the rotational torque generated by the motor 54 is in the region (c), the generated power based on the electromotive force is regenerated. Further, the PWM control of the switching element described above also controls the amount of current flowing through each coil of the motor 54 by electromotive force, and the rotational torque generated by the motor 54 and the rotational direction of the motor 54 are reversed. Even in this case, 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 source or generated by electromotive force. It is designed to control 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, control for damping the sprung vibration and the unsprung vibration (hereinafter referred to as “damping force”). May be referred to as “control”). Further, control for suppressing the roll of the vehicle body (hereinafter sometimes referred to as “roll suppression control”), control for suppressing the pitch of the vehicle body (hereinafter also referred to as “pitch suppression control”), Vehicle body posture control is executed as a combination of these controls. Furthermore, in the present system 10, control for changing the vehicle height for the purpose of improving running stability during high-speed running, ease of getting on and off the vehicle, etc. (hereinafter referred to as "actuator-dependent vehicle height change control"). Control for changing the distance between the vehicle wheels corresponding to each actuator 26 (hereinafter, sometimes referred to as “distance change control”) is executed for each actuator. The vehicle body posture control and the distance change control described above are controls that directly control the distance between the vehicle body wheels as described later in detail, and are controls according to a so-called position control method. The control is referred to as target position dependent control. In the damping force control and the target position dependent control, the target actuator force is determined by adding the damping force component and the target position dependent component, which are components of the actuator force for each control, and the actuator 26 generates the target actuator force. By being controlled in this way, it is executed centrally. In the suspension system 10, the air spring 28 is used to control the vehicle height based on the driver's intention for the purpose of dealing with rough roads (hereinafter, “air spring dependent vehicle height change control”). May be executed). In the following description, the actuator force and its component are positive values corresponding to the force in the direction separating the vehicle body and the wheel 12 (rebound direction), and the direction causing the vehicle body and the wheel 12 to approach (bound The one corresponding to the (direction) force is treated as a negative value.

i) Air Spring Dependent Vehicle Height Change Control The air spring dependent vehicle height change control for changing the vehicle height by the air spring 28 is a set vehicle height to be realized by operating the vehicle height change switch 166 based on the driver's intention. It is executed when a certain target set vehicle height is changed. A target vehicle body distance L _S ^* for each wheel 12 is set according to each of the three set vehicle heights, and the vehicle body for each wheel 12 is determined based on the detection value of the stroke sensor 164. The operation of the air supply / discharge device 80 is controlled so that the distance between the wheels becomes the target distance L _S ^*, and the distance between the vehicle bodies of each wheel 12 is changed to a distance corresponding to the target set vehicle height. Further, in the present suspension system 10, when the vehicle speed v is higher than the threshold speed v ₀ (for example, 50 km / h) at the Hi vehicle height, the vehicle is returned to the N vehicle height in view of the running stability of the vehicle. The air spring dependent vehicle height change control is also executed in this case. Further, in this air spring dependent vehicle height change control, for example, so-called auto-leveling control is performed for the purpose of coping with a change in the vehicle height due to a change in the number of passengers, a change in the load amount of the load, and the like.

Specifically, in the operation of the air supply / exhaust device 80 when raising the vehicle height (hereinafter sometimes referred to as “vehicle height increase operation”), first, the pump motor 94 is activated and all the individual control valves are operated. When the valve 102 is opened, compressed air is supplied to the pressure chamber 44 of the air spring 28. After this state is continued, and vehicle body wheel distance target distance L _S ^* and turn individual control valve 102 from what was is closed, the wheel-body distance for all of the wheels 12 and target distance L _S ^* After that, the operation of the pump motor 94 is stopped. In the operation of the air supply / exhaust device 80 for lowering the vehicle height (hereinafter sometimes referred to as “vehicle height reduction operation”), first, the exhaust control valve 114 is opened and all the individual control valves 102 are opened. By being valved, air is exhausted from the pressure chamber 44 of the air spring 28 to the atmosphere. Then, turn individual control valve 102 from that between wheel-body distance is the target distance L _S ^* is closed, after the vehicle wheel distance for all the wheels 12 becomes the target distance L _S ^*, exhaust control The valve 114 is closed. When auto leveling is performed, the individual control valve 102 corresponding to the vehicle whose height needs to be changed is opened, and air is supplied or exhausted.

  However, the above-described vehicle height increasing operation and vehicle height decreasing operation are prohibited from being executed when a specific prohibition condition (hereinafter sometimes referred to as “vehicle height change prohibition condition”) is satisfied. Specifically, a roll moment and a pitch moment are acting on the vehicle body, at least one of the vehicle body and the wheel 12 is moving in the vertical direction with an acceleration equal to or greater than a set value, and the distance between the four vehicle body wheels is If even one of the items not exceeding a certain allowable range is satisfied, the operation of the air supply / discharge device 80 is prohibited. In that case, the individual control valve 102 is closed, the pump motor 94 is stopped or the exhaust control valve 114 is closed, and the amount of air in the pressure chamber 44 of the air spring 28 is determined at that time. Air volume is maintained.

Incidentally, the reference distance L _B to be used in the target position relying control described later are vehicle wheel distance in a state in which the actuator 26 is not generating the actuator force. That is, in each wheel 12, wheel-body distance L _S ^* is maintained by the air spring 28 is a reference distance L _B. When the vehicle height increase operation and the vehicle height decrease operation are prohibited during execution due to the vehicle height prohibition condition, the distance between the vehicle body wheels when the execution is prohibited is set as the reference distance L _B. The

ii) Target position-dependent control The target position-dependent control adjusts the distance between the vehicle body wheels for each wheel 12 by an actuator force for the purpose of controlling the posture of the vehicle body or changing the vehicle height. In this target position-dependent control, the distance between the vehicle body wheels that is a target for each wheel 12 based on the roll suppression control, pitch suppression control, and distance change control (hereinafter sometimes simply referred to as “target distance”). L ^* is determined, to control the actuator 26 so that between the wheel-body distance is the target distance, the target position relies component F _T of the actuator force is determined.

Target distance L ^* is roll control, pitch reduction control, for each control of the distance changing control, adjusting the distance from the reference distance L _B actuator 26 is the distance between the wheel-body in a state that is not to generate the actuator force The roll suppression component δL _R , the pitch suppression component δL _P , and the distance change component δL _H are determined and are determined by adding them together.
L ^* = L _B + δL _R + δL _P + δL _H
Then, a vehicle body wheel distance deviation ΔL (= L ^* −Lr), which is a deviation of the actual vehicle wheel distance Lr detected by the stroke sensor 164 from the target distance L ^* , is recognized, and the vehicle body wheel distance deviation ΔL is 0. Thus, the target position dependent component _FT is determined. Its target position relies component F _T is the ECU 140, based on the vehicle wheel distance deviation [Delta] L, is determined according to the following equation of the PID control law.
F _T = K _P · ΔL + K _D · ΔL '+ K _I · int (ΔL)
Here, the first term, the second term, and the third term are a proportional term component (P term component), a differential term component (D term component), and an integral term component (I term component) in the target position dependent component F _A , respectively. ), And K _P , K _D , and K _I mean proportional gain, differential gain, and integral gain, respectively. Int (ΔL) corresponds to an integral value of the vehicle body wheel distance deviation ΔL. Hereinafter, the roll restraining control, pitch restraining control, each of the distance changing control will be described roll-reduction component [delta] L _R, pitch-reduction component [delta] L _P, the method of determining the distance changing component [delta] L _H in the center.

a) Roll Suppression Control When the vehicle is turning, the vehicle body and the wheel 12 on the turning inner wheel side are separated from each other and the vehicle body and the wheel 12 on the turning outer wheel side are brought close to each other by the roll moment resulting from the turning. FIG. 6A is a diagram showing the relationship between the lateral acceleration Gy indicating the roll moment and the change amount δL of the distance between the vehicle wheels, and the broken line in this diagram is a case where the actuator 26 is not operated. . In the roll suppression control, the actuator is controlled so that the distance between the vehicle wheels shown in the solid line in FIG. 6 (a) corresponds to the magnitude of the roll moment in order to suppress the separation on the turning inner wheel side and the approach on the turning outer wheel side. 26 is controlled. Specifically, first, as the lateral acceleration indicating the roll moment received by the vehicle body, the estimated lateral acceleration Gyc estimated based on the steering angle δ of the steering wheel and the vehicle speed v, and the actual acceleration measured by the lateral acceleration sensor 174 are used. Based on the 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-reduction component [delta] L _R of the adjustment distance is determined. Specifically, the in the controller 142 are stored map data shown in FIG. 6 (a) of the roll-reduction component [delta] L _R for the the control-use lateral acceleration Gy ^* as a parameter is, by referring to the map data, the roll-reduction component [delta] L _R is determined.

b) Pitch suppression control With respect to the nose dive of the vehicle body generated during braking of the vehicle body, the vehicle body on the front wheel side and the wheel 12 are brought close to each other by the pitch moment that generates the nose dive, and the rear wheel side The vehicle body and the wheel 12 are separated. Further, for the squat of the vehicle body generated during acceleration of the vehicle body, the vehicle body on the front wheel side and the wheel 12 are separated by the pitch moment that generates the squat, and the vehicle body and wheel 12 on the rear wheel side are separated. Is approached. FIG. 6B is a diagram showing the relationship between the longitudinal acceleration Gx indicating the pitch moment and the change amount δL of the distance between the vehicle body wheels, and the broken line in this figure is a case where the actuator 26 is not operated. . In the pitch suppression control, in order to suppress the approach / separation distance in these cases, the actuator 26 is controlled so as to be the distance between the vehicle wheels shown by the solid line in FIG. 6B according to the pitch moment. Specifically, the actual longitudinal acceleration Gx measured by the longitudinal acceleration sensor 172 is adopted as the longitudinal acceleration indicating the pitch moment received by the vehicle body, and the pitch suppression component δL _P of the adjustment distance is based on the actual longitudinal acceleration Gx. It is determined. Specifically, the map data shown in FIG. 6B, that is, the map data of the pitch suppression component δL _{P using} the longitudinal acceleration Gx as a parameter is stored in the controller 142. With reference to the map data, A pitch suppression component δL _P is determined. 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.

c) Distance change control In this suspension system 10, when the vehicle speed v is greater than or equal to the threshold speed v ₁ (for example, 80 km / h) at the N vehicle height, in consideration of the running stability of the vehicle, The vehicle height is changed to “high vehicle height at high speed” which is a low vehicle height (a vehicle height higher than a set low vehicle height). Further, in order to make it easier for the driver to get on and off and to load and unload luggage, the vehicle height is changed to “vehicle height when getting on and off”, which is a vehicle height that is lower than the Low vehicle height. The vehicle height change control in these cases is performed by the actuator 26, and the control executed for each of the actuators 26 is distance change control. Specifically, the distance change component δL _H of the adjustment distance for each wheel 12 is determined according to the target vehicle height at high speed or when getting on and off. However, as shown in FIG. 7, the distance changing component δL _H is gradually decreased according to the time t so that the target distance L ^* does not change suddenly. Similarly, the distance changing component δL _H is gradually increased when returning from the vehicle height at high speed or the vehicle height at the time of getting on / off to N vehicle height.

iii) Damping force control In the damping force control, a damping force 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. . Specifically, the vertical movement speed of the vehicle mount unit 24 calculated based on the vertical acceleration detected by the vertical acceleration sensor 176 provided on the vehicle mount unit 24, so-called sprung speed V _U Based on the vertical movement speed of the wheel calculated based on the vertical acceleration detected by the vertical acceleration sensor 178 provided on the lower arm 22, the so-called unsprung speed V _L , the damping force component F _V is calculated.
F _V = C _U・ V _U −C _L・ V _L
Here, C _U is a gain for generating a damping force corresponding to the vertical operating speed of the mount 24 of the vehicle body, and C _L is a damping force corresponding to the vertical operating speed of the wheel 12. It is a gain for generating. That is, C _U and C _L can be considered as damping coefficients for so-called sprung and unsprung absolute vibrations. Note that the damping force component F _V can be determined by other methods. For example, in order to execute a control for generating a damping force based on the unsprung unsprung relative speed, an index value of the relative speed between the vehicle body and the wheel 12 is obtained from a detection value of the rotation angle sensor 184 provided in the motor 54. Based on the rotation speed ω of the obtained motor 54, it can be determined according to the following equation.
F _V = C · ω (C: damping coefficient)

The damping force control is executed only when it can be considered that vibrations of a set frequency or higher (for example, 1 Hz or higher) are occurring. Specifically, when the detection value of any of the vertical acceleration sensors 176 and 178 is equal to or greater than the set value, the damping force component F _V is determined according to the above equation. When the damping force control is not executed, the damping force component F _V is determined to be zero.

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. More specifically, when the target position-dependent component F _T and the damping force component F _V of the actuator force are determined as described above, the target actuator force F ^* is determined based on the following equations.
F ^* = F _T + F _V
However, when the damping force control is executed, in determining the target position relies component F _T, the proportional term component K _P · [Delta] L and a derivative term component K _D · ΔL 'is designed to be zero. In that case, only the integral term component K _I · int (ΔL), ie, only the actuator force component necessary for the motor 54 to maintain the current rotational position is set to the target position relying component F _T, the is added to the target position relying component F _T and the damping force component F _V is the above target actuator force F ^* is determined. This reduces the interference of the target position-dependent control with the damping force control. 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.

≪Brake control in distance change control≫
In the distance change control, when the distance between the vehicle body wheels is changed to the target vehicle body wheel distance by the actuator 26, the actuator 26 reaches the target against the elastic force of the air spring 28. Therefore, the actuator 26 generates the actuator force to maintain the distance by the amount of the loss of the balance between the elastic force of the air spring 28 and the shared load when the target is reached. When the distance between the vehicle wheels is changed toward the reference distance, the balance between the elastic force of the air spring 28 and the shared load is utilized to reduce the distance between the vehicle wheels toward the reference distance. The motor 54 can be operated to generate an electromotive force. In the suspension system 10, it is possible to execute specific braking force generation control for generating an actuator force as a braking force having a specific magnitude depending on the electromotive force with respect to the relative movement between the vehicle body and the wheel 12. It is said that. Specifically, as the specific braking force generation control, when the charge amount (= remaining amount) E of the battery 150 detected by the charge amount sensor 186 is relatively large (set value E ₀ or more), each of the motors 54 By short-circuiting the energization terminals of the phases, short-circuit braking control for generating an actuator force as a braking force is executed. Further, when the charge amount E is smaller than the set value E ₀ , the actuator power is controlled so as to maximize the regenerative power amount while regenerating the generated power that depends on the electromotive force to the battery 150. Specific braking force regeneration control that is generated as power is executed. The specific braking force generation control is a case where the present system 10 executes only the distance change control without executing the damping force control and the vehicle body posture control, and the distance between the vehicle wheels is used as a reference in the distance change control. It is executed when returning to the distance. Hereinafter, the short-circuit braking control and the specific braking force regeneration control will be described in detail.

i) Short-circuit braking control The short-circuit braking control is a control in which an actuator force is generated as a braking force by short-circuiting the energization terminals of each phase of the motor 54. Specifically, all of the high-side switching elements HUS, HVS, and HWS of the inverter 146 are turned on (closed state), and all of the low-side switching elements LUS, LVS, and LWS are turned off (open state). As a result, the switching elements HUS, HVS, HWS and the free-wheeling diodes arranged in parallel to each other cause the energization terminals of each phase of the motor 54 to be short-circuited to each other. As a result, when the vehicle body wheel distance is returned to the reference distance in the distance change control, an electromotive force is generated in the motor 54, and an actuator force based on the electromotive force is generated. The actuator force becomes a braking force having a specific magnitude according to the short-circuit characteristic line shown in FIG. 5 according to the fluctuation speed of the distance between the vehicle body wheels (the rotational speed ω of the motor 54). In other words, in this short-circuit braking control, the power consumption of the battery 150 in this control can be reduced to zero by generating an actuator force based on the electromotive force generated in the motor 54. It becomes possible to suppress consumption.

ii) Specific braking force regenerative control In addition, the specific braking force regenerative control controls the actuator force so that the amount of regenerated electric power is maximized while regenerating the generated power that depends on the electromotive force to the battery 150. This control is generated as power. Specifically, the target actuator force F ^* of the actuator 26 is determined according to the following equation so that the braking force is ½ of the braking force obtained when the current-carrying terminals of each phase of the motor 54 are short-circuited. .
F ^* = (1/2) · C _S · ω (C _S : damping coefficient when following short-circuit braking)
Based on the determined target actuator force F ^* , a target duty ratio is determined, and a command based on the duty ratio is transmitted to the inverter 146. The inverter 146 sets the appropriate duty ratio to drive the motor 54 so as to generate braking force while regenerating the generated power to the battery 150. In this specific braking force regenerative control, the actuator force is generated and regenerated as a braking force having a magnitude half that of the braking force obtained when the current-carrying terminals of each phase of the motor 54 are short-circuited. The amount of power is the largest. That is, the suspension system 10 can efficiently regenerate power and suppress power consumption of the system 10.

iii) Coping with vehicle body inclination in distance change control When the above-mentioned specific braking force generation control is executed for each of the four actuators 26, for example, some of the four actuators 26 If the fluctuation speed of the distance between the vehicle body wheels is different from the fluctuation speed of the other actuators 26, the vehicle body may be inclined. However, in the present suspension system 10, control is performed so as not to cause the vehicle body to tilt.

In the present suspension system 10, when the distance between the vehicle body wheels is changed toward the reference distance, as described above, the distance change component δL _H is gradually increased with respect to the time t, so that the target distance L ^* Is gradually changed. Specifically, the target distance L ^* of each actuator 26 is a fluctuation speed that takes a suitable margin from a fluctuation speed of the distance between vehicle body wheels estimated when the specific braking force generation control is executed in a normal state. It is made to change gradually so that it may become. Further, in the present system 10, the specific braking force generation control, when changing toward the vehicle wheel distance to the reference distance, in other words, closer to the reference distance L _B than the target distance L ^* is the actual vehicle wheel distance Lr If executed. Therefore, in some of the actuators 26 in a very fast changing speed of the vehicle wheel distance, when the actual vehicle wheel distance Lr is close to the reference distance L _B exceeds the target distance L ^* is partially The specific braking force generation control is not executed for the actuator 26, and position control according to the PID control law is executed. In other words, an actuator force that causes the distance between the vehicle wheels to be the target distance L ^* is generated for the actuator 26 having a fast fluctuation speed of the distance between the vehicle wheels. Therefore, in the present suspension system 10, when changing the distance between the vehicle body wheels of each of the four wheels 12 toward the reference distance, the suspension system 10 is controlled so as to hardly cause the vehicle body to be inclined.

≪Control program≫
The control of the air spring 28 and the control of the actuator 26 as described above are performed in a short time interval (for example, several milliseconds) by the air spring control program shown in the flowchart in FIG. 8 and the actuator control program shown in the flowchart in FIG. This is performed by being repeatedly executed by the controller 142 at a time of ˜several tens of milliseconds. A vehicle equipped with the suspension system 10 employs an electronic key, and a sensor (not shown) provided in the vehicle uses the electronic key when the electronic key is within a predetermined range from the vehicle. It can be detected. The above two programs are executed from when the electronic key is detected by the sensor until a predetermined time (for example, 60 seconds) elapses after the electronic key is not detected. Of the processes according to these two control programs, the process of changing the vehicle height is performed based on the target vehicle height, that is, the determination of the target vehicle height, that is, the determination of the distance between the target vehicle body wheels and the vehicle body. The determination of the distance change component of the inter-wheel adjustment distance is performed by executing a target vehicle height determination program whose flowchart is shown in FIG. The target vehicle height determination program is executed in parallel with each other for the same period as the previous two control programs. Below, the flow of each control is demonstrated easily, referring the flowchart shown in a figure.

In i) the target vehicle height determining program target vehicle height determining program, the target vehicle is a flag indicating vehicle height reaches the target height flag f _H is used, the target set vehicle height is determined on the basis of the flag f _H. In this suspension system 10, the basic vehicle height is “standard vehicle height” (hereinafter, sometimes referred to as “N vehicle height”), “Low vehicle height” lower than N vehicle height, and “N vehicle height” higher than “N vehicle height”. are three vehicle height setting of the Hi vehicle height ", the flag value of the target vehicle height flag _{f H [1], [2} ], [3] , respectively, Low vehicle height, N ride height, Hi vehicles It is supposed to correspond to high. Basically, depending on whether the command based on the operation of the vehicle height change switch 166 is a vehicle height increase command or a vehicle height decrease command, the target vehicle height flag f is set to either the high vehicle height side or the low vehicle height side. The flag value of _H is changed.

Further, in the present suspension system 10, the vehicle speed-sensitive vehicle height change is executed, and the vehicle speed v is higher than the threshold speed v ₀ (for example, 50 km / h) at the Hi vehicle height (f _H = 3). In this case, in view of the running stability of the vehicle, the flag value is changed to [2] so as to return to N vehicle height. In addition, when the vehicle speed v is equal to or higher than the threshold speed v ₁ (for example, 80 km / h) at the N vehicle height (f _H = 2), it is lower than the N vehicle height by δL in view of further running stability of the vehicle. The flag value corresponding to “high-speed vehicle height” which is a vehicle height (a vehicle height higher than the Low vehicle height) is set to [2 ′]. Incidentally, once the vehicle speed after becoming a threshold speed v ₁ or more, when it becomes a threshold speed v less than ₁ is to return to the N vehicle height.

Further, in the present suspension system 10, the vehicle height is changed when getting on and off as control for facilitating getting on and off of the driver and loading and unloading of luggage. As the vehicle height at the time of getting on and off, “vehicle height at the time of getting on and off”, which is lower than the Low vehicle height, is set. When the vehicle height at the time of getting on and off is changed, the target vehicle height is flag f _H is a flag value corresponding to the passenger when the vehicle height is [0], if the passenger is carrying the electronic key is moved outside the range that can be detected by the sensor, the flag of the target vehicle height flag f _H The value is set to [2]. Incidentally, in this case, after returning to the vehicle height before the flag value is set to [0] by the distance change control of the actuator 26, the air spring 28 adjusts to the vehicle height corresponding to the flag value [2]. It has become so. Conversely, when the passenger is carrying the electronic key within the range that can be detected by the sensor, the flag value of the target vehicle height flag f _H is [0], when the ignition switch 160 is turned ON , the flag value of the target vehicle height flag f _H is set to be a [2].

In the target vehicle height determination program, step 47 (hereinafter abbreviated as “S47”) is also performed in correspondence with each of the above-described values of the flag f _H [1], [2], [3]. In the same manner, the vehicle body wheel distance L _S ^{* which} is the target of the vehicle height change control by the air spring 28 is set to L ₁ , L ₂ and L ₃ . The value of the flag f _H is [0], [2 '] in the case of the wheel-body distance as a target in accordance with the target set vehicle height corresponding to each of L _0, L _2' be The distance change component δL _H used in the target position-dependent control by the actuator 26 is determined by executing the decrease distance change component determination subroutine in S49 or the increase distance change component determination subroutine in S50. Incidentally, when the value of the flag f _H is [1], [2], [3], the distance change component δL _H is set to 0 in S48.

The decreasing distance change component determination subroutine is a routine shown in the flowchart of FIG. 11, and is a distance when approaching the target vehicle body wheel distances L ₀ and L _{2 ′} corresponding to the flag values [0] and [2 ′]. This is a routine for determining the change component δL _H. In this subroutine, the distance changing component δL _H is decreased by δL _D every time the program is executed. Then, if the distance changing component δL _H is reduced to the difference between the reference distance L _B that is the distance between the vehicle body wheels in a state where the actuator 26 does not generate the actuator force and the target vehicle wheel distance, the target The difference is maintained so as to maintain the distance between the vehicle body wheels. Further, when the distance between the vehicle wheels is changed toward the reference distance L _B , the distance change component δL _H is determined by executing the increasing distance change component determination subroutine in the flowchart of FIG. In this subroutine, the distance change component δL _H is increased by δL _I every time the program is executed until it becomes zero. When the distance change component δL _H becomes 0, the flag value of the vehicle height change flag f _H is set to [2].

ii) Air spring control program The air spring control program is executed for each wheel 12 individually. In this control program, firstly, whether in S1, whether they meet the vehicle height change prohibition condition described above is determined, in S5, the target vehicle height flag f _H is [0] or [2 '] Is determined. Is determined not to satisfy the vehicle height change prohibition condition, when the target vehicle height flag f _H is determined not to be [0] or [2 '], at S6, 7, corresponding to the wheels 12 The actual vehicle-to-wheel distance Lr at this time is compared with the target distance L _S ^* that is the target vehicle-to-wheel distance according to the flag value of the target vehicle height flag f _H. If it is determined that the distance between the vehicle body wheels needs to be increased, it is determined in S8 that air is supplied to the pressure chamber 44 of the air spring 28, and conversely, the distance between the vehicle body wheels needs to be decreased. If this happens, air is discharged from the pressure chamber 44 of the air spring 28 in S9. Also, if they meet the vehicle height change prohibition condition, if the target vehicle height flag f _H is [0] or [2 '], if it is determined that there is no need to change the wheel-body distance is In S10, the air amount is maintained as described above. In this program, as described above, in S2-4, the vehicle body wheel distance L _S ^* maintained by the air spring 28 is set as the reference distance L _B, and execution is prohibited due to the vehicle height prohibition condition. When the execution is prohibited, the distance between the vehicle body wheels when the execution is prohibited is set as the reference distance L _B. After the series of processes described above, one execution of this program ends.

ii) Actuator control program The actuator control program is executed for each of the actuators 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 process, the damping force component F _V is a component of the actuator force, a target position relies component F _T are determined, respectively.

In this program, first, in S11～13, as described above, the reference distance L _B roll-reduction component is a component of the adjustment distance from the [delta] L _R, the pitch restrain component [delta] L _P are determined, respectively, the rolls suppression A target distance L ^* (= L _B + δL _R + δL _P + δL _H ) is determined based on the component δL _R , the pitch suppression component δL _P, and the distance change component δL _H determined in the target vehicle height determination program. Next, a vehicle body wheel distance deviation ΔL (= L ^* −Lr), which is a deviation of the actual vehicle body wheel distance Lr with respect to the determined target distance L ^*, is recognized, and the vehicle body wheel distance deviation ΔL becomes zero. as such, the target position relies component F _T of the actuator force is determined.
F _T = K _P · ΔL + K _D · ΔL '+ K _I · int (ΔL)
However, in S15, it is determined whether or not damping force control is necessary. If so, the damping force component F _V is determined, and the proportional gain K _P and the differential gain K _D are 0 as described above. It is said. When the damping force control is not necessary, the damping force component F _V is set to 0, and the proportional gain K _P and the differential gain K _D are set to specified values.

Next, in S22 and S23, it is determined whether or not to execute the specific braking force generation control. Specifically, in S22, the roll moment on the vehicle body, it is determined whether pitch moment is acting is, in S23, whether or not to change toward a vehicle wheel distance to the reference distance L _B is the target distance L ^* is determined by whether close to the reference distance L _B from the vehicle body actual wheel distance Lr. More specifically, is the difference | L _B −L ^* | between the target distance L ^* and the reference distance L _B smaller than the difference | L _B −Lr | between the actual vehicle body wheel distance Lr and the reference distance L _B. Determined by whether or not. Roll moment on the vehicle body, not acts pitch moment, and, if you are changing toward the vehicle wheel distance to the reference distance L _B, that perform particular braking force generation control. If you do not perform braking control, the damping force component F _V and the target actuator force sum of the target position relying component F _T F ^* is determined, the duty ratio determined based on the target actuator force F ^* A corresponding control signal is transmitted to the inverter 146.

In addition, when it is determined that the specific braking force generation control is to be executed, if the amount of charge of the battery 150 is not large, it is desirable to regenerate the generated power based on the electromotive force in the battery 150. Therefore, when it is determined in S24 that the amount of charge of the battery 150 is not large, specific braking force regeneration control is executed in S25. Specifically, the target actuator force F ^* is determined by the above-described formula F ^* = (1/2) · C _S · ω, and a control signal corresponding to the duty ratio determined based on the target actuator force F ^* is obtained. Is transmitted to the inverter 146. If it is determined in S24 that the amount of charge of the battery 150 is large, short-circuit braking control is executed in S26, and the ON / OFF state of the switching element is set to the high-side switching element as described above. A control signal is transmitted to the inverter 146 so that all of the HUS, HVS, and HWS are in an ON state (closed state), and all of the low-side switching elements LUS, LVS, and LWS are in an OFF state (open state). After the series of processes described above, one execution of the actuator control program ends.

<Functional configuration of control device>
FIG. 13 is a functional block diagram schematically showing the functions of the ECU 140 described above. Based on the above function, the controller 142 of the ECU 140 includes a target vehicle height determination unit 200 that determines the target vehicle height, an air spring-dependent vehicle height change control unit 202 that changes the vehicle height depending on the air spring 28, and an actuator. An actuator-dependent vehicle height change control unit 204 that changes the vehicle height depending on H. 26, a damping force control unit 206 that determines a damping force component F _V of the actuator force generated by the actuator 26, and a roll moment and a pitch moment. The vehicle body posture control unit 208 that controls the posture of the vehicle body to suppress the vehicle body is configured. The actuator-dependent vehicle height change control unit 204 is configured to include a distance change control unit 210 that changes the distance between vehicle body wheels corresponding to each of the four actuators 26. A distance change component determining unit 212 that determines a distance change component δL _H of the adjustment distance with respect to the reference distance, and a specific braking force generation control unit 214 that executes specific braking force generation control are provided. The vehicle body posture control unit 208 also includes a roll suppression control unit 216 that determines a roll suppression component δL _R of the adjustment distance with respect to a reference distance of the distance between the vehicle body wheels, and a pitch suppression control unit that determines the pitch suppression component δL _P of the adjustment distance. and a 218, a vehicle body attitude control unit 208, and a distance changing component determination unit 212 of the distance change control unit 210, a target position relying control unit 220 for determining a target position relying component F _T of the actuator force Is configured. Further, the specific braking force generation control unit 214 includes a short-circuit braking control unit 222 that performs short-circuit braking control, and a specific braking force regeneration control unit 224 that performs specific braking force regeneration control. Incidentally, in the ECU 140 of the suspension system 10, the specific braking force generation control unit 214 is configured to include a part for executing the processing of S22 to S26 of the actuator control program.

≪Modification≫
In this modification, the control for changing the vehicle height by the actuator 26 is different from the control in the above embodiment. Specifically, in the actuator-dependent vehicle height change control, as shown in FIG. 14 (a diagram when changing to the vehicle height at the time of getting on and off and returning from the vehicle height), the vehicle speed at the target high speed or the vehicle at the time of getting on and off When changing to high, as in the above embodiment, the distance change component δL _H is gradually changed according to time t so that the target distance L ^* does not change suddenly. In this modification, when changing from the vehicle height at high speed or the vehicle height at getting on / off to the reference distance L _B , the distance change component δL _H is immediately set to 0, and the target distance L ^* becomes the reference distance L _B. It can be changed suddenly. Incidentally, if so sudden change the target distance L ^* to the reference distance L _B, until between wheel-body distance is returned to the reference distance L _B, a position control in accordance with the PID control law is not executed, the specific braking force Generation control is performed. In this case, the distance between the vehicle body wheels is changed as shown by a one-dot chain line in FIG. 14 by the specific braking force generation control.

In the present modification, the distance change component δL _H is determined in the target vehicle height determination program shown in the flowchart of FIG. 15 which is executed instead of the target vehicle height determination program of FIG. Specifically, when changing toward the vehicle wheel distance to the reference distance, in S81, whether the actual vehicle wheel distance Lr becomes the reference distance L _B is determined, the actual wheel-body distance Lr In step S48, the distance changing component δL _H is set to 0 until the reference distance L _B is reached. Further, when the actual vehicle wheel distance Lr becomes the reference distance L _B, in S82, the flag value of the vehicle height change flag f _H is set to [2].

  Also in this modification, when changing the distance between the vehicle body wheels toward the reference distance, the specific braking force generation control similar to that in the above-described embodiment is executed for each of the four actuators 26. That is, when the charge amount of the battery 150 detected by the charge amount sensor 186 is relatively large, the short-circuit braking control is executed, and when the charge amount E is small, the specific braking force regeneration control is executed. . However, when changing the distance between the vehicle body wheels for each of the four wheels 12 toward the reference distance, if the fluctuation speed of the vehicle body wheel distance for each of the wheels 12 is different, a relatively large inclination is generated in the vehicle body. May end up. Therefore, the actuator-dependent vehicle height change control is control that does not cause the vehicle body to tilt more than a set level. Specifically, when the vehicle body is tilted more than the set level, the specific braking force generation control for a part of the four actuators 26 is prohibited and a part of the part is prohibited. Inclination suppression control for generating the actuator force as a force for suppressing the inclination of the vehicle body is executed. The inclination suppression control is a control that prevents the distance between the vehicle body wheels of each of the four wheels 12 from preceding the other distance by a set distance or more. Specifically, when the difference between the distance between the vehicle body wheels of the actuator 26 with the slowest fluctuation speed of the distance between the vehicle body wheels and the distance between the vehicle body wheels of the other actuators 26 exceeds a set value, the difference is set. In this control, an actuator force that eliminates the difference is generated for the actuator 26 that has exceeded the value.

The control as described above is performed by executing the actuator control program shown in the flowchart of FIG. 16, which is executed in place of the actuator control program of FIG. Specifically, the distance change control when changing the distance between the vehicle body wheels toward the reference distance is performed by executing a specific time distance change control subroutine shown in the flowchart of FIG. 17 in S91 of the actuator control program. In particular when the distance change control subroutine, first, in S101, 4 one of a vehicle body actual wheel distance Lr for the wheel 12, the changing speed of the vehicle wheel distance is the slowest vehicle wheel distance slowest actuators distance Lr _{( late)} is certified. Next, in S102, a deviation of the actual vehicle wheel distance Lr with respect to the latest actuator distance Lr _(late) to the latest actuator distance deviation ΔL _(late) is obtained. _When the absolute value of _(late) is greater than or equal to the threshold distance Le, the specific braking force generation control in S105 and below is prohibited, and the inclination suppression control in S104 is executed. In S104, the target actuator force F ^* is determined in accordance with the PID control law based on the slowest actuator distance deviation ΔL _(late) so that the slowest actuator distance deviation ΔL _(late) is zero.

FIG. 18 is a functional block diagram schematically showing the function of the ECU 140 in this modification. In this modification, the distance change control unit 210 and the distance change component determination unit 212 that determines the distance change component δL _H of the adjustment distance with respect to the reference distance of the distance between the vehicle body wheels and the specific control that executes the specific braking force generation control. In addition to the power generation control unit 214, a tilt suppression control unit 250 that executes tilt suppression control is provided. In addition, in ECU140 of a present Example, the inclination suppression control part 250 is comprised including the part which performs the process of S101-S104 of the specific time distance change time control subroutine.

  Also in the suspension system of the present modified example, when the specific braking force generation control is executed, the power consumption is reduced to 0 or the battery when the distance between the vehicle body wheels is changed toward the reference distance, as in the above-described embodiment. Since it is possible to regenerate power to 150, it is possible to suppress power consumption of this system.

1 is a schematic diagram showing the overall configuration of a vehicle suspension system that is an embodiment of the claimable invention. It is front sectional drawing which shows the spring absorber Assy shown in FIG. It is a schematic diagram which shows the spring absorber assembly and air supply / discharge device shown in FIG. It is a circuit diagram of the inverter which drives the electric motor with which the actuator of FIG. 2 is provided. It is a figure which shows the relationship between the rotational speed and rotational torque of an electric motor with which the actuator of FIG. 2 is provided. It is a figure which shows the relationship between the lateral acceleration which generate | occur | produces in a vehicle body, and the variation | change_quantity of the distance between vehicle body wheels, and the relationship between the longitudinal acceleration which generate | occur | produces in a vehicle body, and the variation | change_quantity of the distance between vehicle body wheels. It is a figure which shows the change of the distance between target vehicle body wheels with respect to time passage. It is a flowchart showing the air spring 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 shown in FIG. It is a flowchart showing the target vehicle height determination program executed by the suspension electronic control unit shown in FIG. It is a flowchart which shows the distance change component determination subroutine at the time of reduction | decrease performed in a target vehicle height determination program. It is a flowchart which shows the distance change component determination subroutine at the time of increase performed in a target vehicle height determination program. It is a block diagram which shows the function of the suspension electronic control unit of FIG. It is a figure which shows the change of the target vehicle body wheel distance with respect to time passage, and the actual vehicle body wheel distance in the vehicle suspension system of a modification. It is a flowchart which shows the target vehicle height determination program performed in the suspension system for vehicles of a modification. It is a flowchart which shows the actuator control program performed in the suspension system for vehicles of a modification. It is a flowchart which shows the specific time distance change control subroutine performed in the actuator control program of a modification. It is a block diagram which shows the function of the suspension electronic control unit of a modification.

Explanation of symbols

  10: Vehicle suspension system 20: Spring absorber assembly 22: Lower arm (unsprung member) 24: Mount part (sprung member) 26: Electromagnetic actuator 28: Air spring (suspension spring) 50: Screw rod (male thread part) 52: Nut (female thread portion) 54: Electric motor (brushless DC motor) 80: Air supply / discharge device 140: Suspension electronic control unit (control device) 146: Inverter (drive circuit) 150: Battery (power supply) 186: Charge amount sensor 200: Target vehicle height determination unit 202: Air spring dependent vehicle height change control unit 204: Actuator dependent vehicle height change control unit 206: Damping force control unit 208: Car body posture control unit 210: Distance change control unit 212: Specific Braking force generation control unit 214: Roll suppression control unit 216: Pitch suppression control unit 218: Target position dependence control unit 220: Short-circuit braking control unit 222: Specific braking force regeneration control unit 250: Inclination suppression control unit

Claims (6)

A suspension spring that elastically supports a sprung member that forms part of the vehicle body and an unsprung member that holds the wheel;
An electromagnetic actuator that is provided in parallel with the suspension spring and has an electric motor as a power source, and generates an actuator force that is a force for approaching and separating the vehicle body and the wheel in the vertical direction;
A control device for controlling the operation of the electromagnetic actuator , comprising: (a) vibration damping control for controlling actuator force to attenuate at least sprung vibration; and (b) controlling actuator force to A vehicle suspension system comprising: a control device configured to execute distance change control for changing a distance between vehicle body wheels, which is a distance between a vehicle body and a wheel in a vertical direction in order to change a height. ,
The control device is
In the distance change control when there is no need to control the actuator force in the vibration damping control ,
Maintaining a distance between vehicle body wheels different from a reference distance, which is a vehicle wheel distance in a state where the electromagnetic actuator is not generating an actuator force, by supplying electric power to the electromagnetic actuator to generate an actuator force. From the state, when the power supply to the electromagnetic actuator is stopped and the distance between the vehicle body and the wheel is changed toward the reference distance, the occurrence of the occurrence in the electric motor with respect to the relative operation of the vehicle body and the wheel at that time is changed. A vehicle suspension system that executes specific braking force generation control for controlling an actuator force so that a braking force having a specific magnitude depending on electric power is obtained .   2. The control according to claim 1, wherein the specific braking force generation control is executed by generating an actuator force of the electromagnetic actuator as a braking force having a specific magnitude according to a fluctuation speed of a distance between vehicle body wheels. Vehicle suspension system.   3. The vehicle suspension system according to claim 1, wherein the specific braking force generation control is control that is performed by conducting between the energization terminals of each phase of the electric motor. 4.   The specific braking force generation control regenerates the generated power that depends on the electromotive force generated in the electric motor to a power source that supplies the electric motor, and the amount of electric power that is regenerated is the actuator force of the electromagnetic actuator. The vehicle suspension system according to any one of claims 1 to 3, wherein the suspension system is a control that is executed by generating a braking force that is maximized.   The specific braking force generation control regenerates generated power that depends on the electromotive force generated in the electric motor to a power source that supplies electric power to the electric motor, and the actuator force of the electromagnetic actuator is applied to each phase of the electric motor. 5. The vehicle suspension system according to claim 1, wherein the suspension system is executed by generating a braking force that is ½ of a braking force obtained when the current-carrying terminals are short-circuited. The vehicle suspension system includes a plurality of suspension springs, each of which is the suspension spring, corresponding to a plurality of wheels of the vehicle, and a plurality of electromagnetic actuators, each of which is the electromagnetic actuator,
The control device is
Vehicle height change control that controls the operation of the plurality of electromagnetic actuators and changes the vehicle height of the vehicle by executing the distance change control for each of the plurality of electromagnetic actuators. Is executable,
In the vehicle height change control when it is not necessary to control the actuator force in the vibration damping control ,
When changing the vehicle body wheel distance for each of the plurality of wheels toward the reference distance, (a) for each of the plurality of electromagnetic actuators, the actuator force of each of the plurality of electromagnetic actuators Executing the specific braking force generation control, which is a control executed by generating a braking force having a specific magnitude according to the fluctuation speed of the distance between the vehicle body wheels, and (b) the specific braking force generation control. Any of the plurality of electromagnetic actuators when the vehicle body tilts more than the set level due to the difference in the fluctuation speed of the vehicle body wheel distance for each of the plurality of wheels due to execution . The specific braking force generation control for one or more items is prohibited, and the actuator force for each of the one or more items is restrained from leaning the vehicle body. The vehicle suspension system according to any one of claims 1 to 5 to a tilt suppression control for generating a force to run.

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