JP4775250B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a suspension system that includes an electromagnetic actuator that applies a force that depends on the force of an electromagnetic motor to the relative movement of an unsprung portion and an unsprung portion.

In recent years, as a vehicle suspension system, instead of a conventional suspension system having a hydraulic absorber, for example, an electromagnetic motor for relative movement between an upper part and an unsprung part as described in the following patent document. A suspension system including an electromagnetic actuator that functions as a shock absorber by generating a resistance force that depends on the above-described force, a so-called electromagnetic suspension system has been studied. Such a suspension system is capable of appropriately controlling the magnitude of the resistance force by controlling the force of the electromagnetic motor, and has a high performance because it can easily realize suspension characteristics based on the so-called skyhook theory. Expected to be a suspension system.
Japanese Patent Laid-Open No. 2003-102425 JP 2006-117210 A

  Since the electromagnetic actuator functions as a shock absorber for vibration damping as described above, it 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. The system described in Patent Document 1 addresses the above problem by reducing the power generated by reducing the force generated by the actuator when traveling at high speed. 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 of the present invention generates an actuator by controlling a drive circuit configured to regenerate a current generated by an electromagnetic motor included in the electromagnetic actuator. The control device for controlling the actuator force includes (a) first control for controlling the actuator force based on at least one of the sprung speed and the unsprung speed, and (b) generation of the actuator force exclusively by the electromagnetic motor. In order to be accompanied, the second control for generating an actuator force that is a resistance force of a specific magnitude according to the relative motion speed of the relative motion between the sprung portion and the unsprung portion can be switched. Is done. The vehicle suspension system of the first invention is configured to switch between the first control and the second control based on the traveling speed of the vehicle, and the vehicle suspension system of the second invention The system is configured to switch based on the magnitude of the behavior of the vehicle body.

  In the suspension system of the present invention, for example, the first control is executed when good vibration damping characteristics are required, and in other cases, the current generated by the electromagnetic motor by the second control is always supplied to the power source. It is possible to regenerate and reduce power consumption by the actuator. Therefore, according to the system of the present invention configured to be able to switch between these two controls, 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 the following paragraphs, the paragraph (2) that cites the item (1) corresponds to claim 1, and the term (3) that cites the item (1) corresponds to claim 2. Further, the technical feature described in (4) is added to claim 1 or claim 2 in claim 3, and in any one of claims 1 to 3, the technical feature described in (5). The features to which the features are added correspond to claim 4 respectively.

(1) An electromagnetic motor as a power source is disposed between the spring upper part and the spring lower part, and operates according to the relative movement between the spring upper part and the spring lower part, and also has resistance and propulsive force against the relative movement. An electromagnetic actuator that functions as a shock absorber,
A drive circuit disposed between the electromagnetic motor and the power source, driving the electromagnetic motor, and having a structure capable of regenerating the power generated by the electromagnetic motor based on the electromotive force;
A vehicle suspension system comprising: a control device that controls the actuator force by controlling the drive circuit;
(A) first control for controlling the actuator force based on at least one of sprung speed and unsprung speed; and (b) generation of the actuator force is accompanied by power generation by the electromagnetic motor. In order to achieve this, the second control for generating the actuator force, which is a resistance force having a specific magnitude corresponding to the speed of the relative motion with respect to the relative motion between the sprung portion and the unsprung portion, can be switched. A suspension system for a vehicle.

  The “first control” in the aspect described in this section includes, for example, control based on the so-called skyhook theory that generates a damping force for sprung vibration based on sprung speed, and unsprung vibration based on unsprung speed. It is possible to adopt control based on the so-called ground hook theory for generating a damping force against the, and control for executing both of them. Therefore, in the first control, not only the state in which the electromagnetic motor receives the electric power from the power source to generate a resistance force but also the force in the same direction as the relative motion between the unsprung portion and unsprung portion, i. It can also be a force generating condition. That is, an excellent vibration suppression effect is obtained by the first control. On the other hand, in the first control, since the actuator force is not only a resistance force but also a propulsion force, there is a problem that the amount of electric power consumed in the first control is increased.

  The aspect of this section has been made in view of the above situation, and the control device generates the actuator force based on the electromotive force generated by the electromagnetic motor by using the spring force and the unsprung portion. Resistance force of a specific magnitude according to the speed of relative motion (which may be referred to as “stroke motion” hereinafter because it can be considered as stroke motion with respect to the other of the unsprung and unsprung portions). It is possible to execute the second control for controlling so that the second control and the first control can be switched. In other words, the aspect of this section can be simply expressed as passive control (second control) that generates actuator force exclusively as resistance force, and active control (second control) that generates actuator force not only as resistance force but also as propulsion force in some cases. 1 control) can be considered as a switchable mode. According to the aspect of this section, for example, the first control is executed when a good vibration damping characteristic is required, and the current generated by the electromagnetic motor by the execution of the second control is otherwise performed. It is possible to regenerate power and reduce power consumption by the actuator.

  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 speed of the stroke operation and the actuator force. For the “second control” in this section, for example, a control that generates an actuator force based solely on the electromotive force by fixing the damping coefficient that relates the operating speed of the electromagnetic motor and the force of the electromagnetic motor is adopted. Is possible. In consideration of power saving of the system, it is desirable to control the actuator force so that the current regenerated in the power source is as large as possible.

  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, in addition to the function as a shock absorber, It is possible to employ one having a function of controlling the posture of the vehicle body for the purpose of suppressing the roll and pitch of the vehicle body caused by turning, acceleration / deceleration, and the like. The “electromagnetic motor” that is the power source of the actuator is not particularly limited in its type, and various types of motors such as a brushless DC motor can be adopted, and in terms of operation, it is a rotary motor. Alternatively, a linear motor may be used. As the “drive circuit” for driving the electromagnetic motor, for example, a so-called inverter or the like can be employed. For example, the inverter may have a structure that drives a motor by the operation of a switching element, and it is desirable to adopt a structure that can execute PWM (Pulse Width Modulation) control.

  (2) The control device according to (1), wherein the control device is configured to execute the first control when a traveling speed of the vehicle is relatively high and to execute the second control when the vehicle traveling speed is relatively low. Vehicle suspension system.

  As the traveling speed of the vehicle increases, the vibration generated in the vehicle due to road surface input increases. Therefore, when the traveling speed is high, it is desirable that a favorable vibration damping effect be obtained. That is, according to the aspect of this section, it is possible to effectively switch between the first control and the second control. For example, a mode in which a threshold is set for the traveling speed and the first control and the second control are switched with the threshold as a boundary can be adopted as the mode in this section.

  (3) Item (1) or (2), wherein the control device is configured to execute the first control when the behavior of the vehicle body is relatively large, and to execute the second control when the behavior is relatively small. The vehicle suspension system according to item.

  In general, when driving on rough roads or roads with large undulations, the behavior of the vehicle body becomes relatively large during sudden braking, rapid acceleration, sharp cornering, or the like. Incidentally, the vibration of the vehicle body caused by the vibration of the wheel transmitted to the vehicle body is also included in the behavior of the vehicle body. When the behavior of the vehicle body becomes large, it is desirable to obtain a state in which a good vibration damping effect can be obtained. That is, according to the aspect of this section, it is possible to effectively switch between the first control and the second control. In this embodiment, for example, parameters indicating the magnitude of the behavior of the vehicle body, specifically, longitudinal acceleration (sprung acceleration), longitudinal acceleration, lateral acceleration, It is possible to adopt a mode in which the magnitude of the behavior of the vehicle body is determined or estimated based on the lower acceleration or the like, and the first control and the second control are switched. In this case, the magnitude of the behavior of the vehicle body may be determined from the parameter value at the present time, and the magnitude of the behavior of the vehicle body at the current time is estimated from the degree of change in the parameter value within the set time traced back from the current time. May be.

  (4) The control according to any one of (1) to (3), wherein the second control is control for generating the actuator force that is a resistance force having a magnitude at which a current regenerated by the power source is maximized. Vehicle suspension system.

  (5) The second control is a control for generating the actuator force having a resistance force that is ½ of the resistance force generated when the energization terminals of the electromagnetic motor are short-circuited. Item 4. The vehicle suspension system according to any one of Items (4) to (4).

  If the magnitude of the actuator force to be generated is specified as in the modes described in the above two terms, the regenerated current can be maximized. According to the modes described in the above two terms, It is possible to regenerate current efficiently. The latter mode can also be considered as one mode of the former mode.

  (6) The vehicle suspension system according to any one of (1) to (5), wherein the first control is control for controlling the actuator force based on at least a sprung speed.

  Since the above-mentioned actuator can generate a sufficient damping force with respect to the sprung vibration, it is desirable that the actuator force be controlled based on at least the sprung speed as in the aspect of this section. .

  (7) Item (1) to Item (6), wherein the control device is capable of executing vehicle body posture control that generates the actuator force as a posture control force for suppressing at least one of a roll and a pitch of the vehicle body. The vehicle suspension system according to any one of the above.

  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 or when the vehicle is accelerated or decelerated, for example. 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. The aspect of this section may be an aspect in which the vehicle body posture control is comprehensively executed only with the first control and is not executed when the second control is executed. It may be a mode that is always executed separately from the second control. However, in consideration of the fact that the vehicle body attitude control is a control that generates power only by receiving power from the power source, the vehicle body attitude control is performed when the second control is executed as in the former mode. It is better not to be executed.

  (8) The actuator includes a male screw portion provided on one of the spring upper portion and the spring lower portion, and a female screw that is screwed with the male screw portion, and the electromagnetic motor rotates relative to the male screw portion and the female screw portion. The vehicle suspension system according to any one of (1) to (7), wherein the vehicle suspension system is configured to generate a resistance force and a propulsion force against the relative rotation.

  The mode described in this section is a mode in which the actuator is limited to a type employing a so-called screw mechanism. In this aspect, when a rotary motor is employed as the electromagnetic motor, the rotational force of the motor can be easily converted into a damping force for the stroke operation. In the aspect of this section, it is arbitrary whether the male screw part is provided in the upper part of the spring or the unsprung part, and the female screw part is provided in any of them. 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.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention 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.

≪Suspension system configuration≫
FIG. 1 schematically shows a vehicle suspension system 10 that is an embodiment of the claimable invention. The suspension system 10 includes four independent suspension type suspension devices corresponding to the front, rear, left and right wheels 12, each of which is a spring absorber in which a suspension spring and a shock absorber are integrated. Assy20. The wheel 12 and the spring absorber assembly 20 are generic names, and when it is necessary to clarify which of the four wheels corresponds, as shown in FIG. In some cases, FL, FR, RL, and RR are attached to the front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

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

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

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

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

  From the structure as described above, when the spring upper portion and the spring lower portion 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 a rotational torque to the screw rod 50, and generates a resistance force that prevents the stroke operation against the relative operation (stroke operation) between the sprung portion and the unsprung portion. Is possible. 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 stroke motion of the sprung portion and the unsprung portion. In other words, the actuator 26 has a function of applying a damping force to the stroke operation by an actuator force that is an axial force generated by the actuator 26 itself. The actuator 26 also has a function of causing the actuator force to act as a driving force, that is, a driving force for the stroke operation. With this function, it is possible to execute 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 sprung portion and the unsprung portion in the vertical direction (hereinafter sometimes referred to as “distance between sprung springs”) by the actuator force, It also has a function of maintaining the distance at a predetermined distance. With this function, it is possible to effectively suppress the roll of the vehicle body at the time of turning, the pitch of the vehicle body at the time of acceleration / deceleration, and the adjustment of the vehicle height of the vehicle.

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

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

The vehicle includes an ignition switch [I / G] 160, a vehicle speed sensor [v] 162 for detecting a vehicle traveling speed (hereinafter sometimes abbreviated as “vehicle speed”), and a sprung unsprung state for each wheel 12. Four stroke sensors [St] 164 for detecting the distance, a vehicle height change switch [HSw] 166 operated by the driver for the vehicle height change instruction, an operation angle sensor [δ for detecting the operation angle of the steering wheel 170, longitudinal acceleration sensor [Gx] 172 that detects actual longitudinal acceleration that is the longitudinal acceleration actually generated in the vehicle body, and lateral acceleration sensor [Gy] 174 that detects actual lateral acceleration that is the lateral acceleration actually generated in the vehicle body four vertical acceleration sensors [Gz _U] 176 for detecting a longitudinal acceleration (vertical acceleration) of the vehicle body of the mount portion 24 corresponding to the wheels 12, the wheels 1 Four vertical acceleration sensor for detecting a longitudinal acceleration of the [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, the motor 54 A resolver [θ] 184 for detecting the rotation angle of the rotor is provided, and these are connected to the controller 142. The ECU 140 controls the operation of the spring absorber assembly 20 based on signals from these switches and sensors. Incidentally, the character [] is a symbol used when the above-mentioned switch, sensor, etc. are shown in the drawing. The ROM of the computer of the controller 142 stores a program related to the control of the actuator 26 described later, various data, and the like.

≪Configuration of inverter etc.≫
As shown in FIG. 3, the motor 54 of each actuator 26 is a three-phase brushless DC motor in which coils are star-connected (Y-connected), and is controlled and driven by the inverter 146 as described above. The inverter 146 is a general one as shown in the figure, corresponds to each of the high side (high potential side) and the low side (low potential side), and the U phase which is the three phases of the motor 54. Six switching elements HUS, HVS, HWS, LUS, LVS, and LWS corresponding to each of the V, W, and W phases. Further, the controller 142 of the ECU 140 determines a motor rotation angle (electrical angle) by a resolver 184 provided in the motor 54, and opens and closes the switching element based on the motor rotation angle. The inverter 146 drives the motor 54 by so-called sine wave drive, and the amount of current flowing in each of the three phases of the motor 54 changes in a sine wave shape, and the phase difference differs by 120 ° in electrical angle. Thus, the inverter 146 is controlled. The inverter 146 is configured to energize the motor 54 by PWM (Pulse Width Modulation) control. By changing the ratio (duty ratio) between the pulse-on time and the pulse-off time, the amount of current flowing through the motor 54 ( The magnitude of the rotational torque generated by the motor 54 is changed by changing the energization current amount. Specifically, increasing the duty ratio increases the energizing current amount and increases the rotational torque generated by the motor 54. Conversely, decreasing the duty ratio decreases the energizing current amount. The rotational torque generated by the motor 54 is reduced.

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

FIG. 4 conceptually shows the relationship between the rotational speed ω of the motor 54 and the rotational torque Tq generated by the motor 54. That is, it can be considered to indicate the relationship between the stroke speed V _St that is the speed of the stroke operation and the force F _{M that} can be generated with respect to the stroke operation (which may be considered as the rotational torque Tq). 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 Tq. The region (c) in which the rotational torque generated by the motor 54 with respect to the rotational speed 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 has a resistance force depending on the electromotive force. This is a so-called “regenerative braking region” where torque is generated. Incidentally, the region (b) is a region in which the motor 54 receives a current supplied from the battery 150 and generates a torque that becomes a resistance force, that is, a so-called “reverse braking region”. This is a so-called “power running region” in which a torque is generated as a driving force by receiving a current supplied from.

  Note that the inverter 146 has a structure capable of regenerating current generated by the electromotive force to the battery 150. That is, when the relationship between the rotational speed ω of the motor 54 and the rotational torque Tq generated by the motor 54 is in the region (c), the generated current that relies on the electromotive force is regenerated. Further, when the rotational torque generated by the motor 54 and the rotational direction of the motor 54 are reversed, the PWM control of the switching element described above controls the amount of current flowing through each coil of the motor 54 by electromotive force. Thus, the magnitude of the rotational torque generated by the motor 54 is changed by changing the duty ratio. That is, the inverter 146 controls the current flowing through the coil of the motor 54, that is, the energization current of the motor 54, regardless of whether the current is supplied from the power supply or the generated current caused by the electromotive force. It is structured to control the motor force.

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

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

i) Vibration damping control In the vibration damping control, a vibration damping component F _V of the actuator force is determined so as to generate an actuator force having a magnitude corresponding to the vibration speed in order to attenuate the vibration of the vehicle body and the wheel 12. . In other words, the control is based on both the control based on the so-called skyhook theory and the control based on the so-called groundhook theory. Specifically, the vertical movement speed of the vehicle body mount portion 24 calculated from the vertical acceleration detected by the vertical acceleration sensor 176 provided on the vehicle body mount portion 24, the so-called sprung speed V _U, and the lower arm On the basis of the vertical movement speed of the wheel 12 calculated from the vertical acceleration detected by the vertical acceleration sensor 178 provided at 22, so-called unsprung speed V _L , the vibration damping component F _V is expressed by the following equation: 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.

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

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

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

≪Specific resistance control≫
As described above, in the suspension system 10, the vibration damping control as the first control for generating the damping force proportional to the vertical speed of the upper and lower parts of the spring and the power supply from the battery 150 are usually used. The overall control with the vehicle body posture control that receives the force and generates the force, that is, the active control is executed, and the amount of power consumed by the actuator 26 increases. Therefore, in the present system 10, the active control is executed when good damping vibration characteristics are required, and in other cases, the current generated exclusively by the motor 54 is regenerated in the battery 150. In addition, specific resistance control for generating an actuator force having a specific magnitude of resistance according to the stroke speed V _St is executed. That is, the specific resistance control is a second control that is a vibration damping control different from the vibration damping control as the first control.

For example, as the traveling speed of the vehicle increases, the vibration generated in the vehicle with respect to road surface input increases. Therefore, when the traveling speed is high, it is desirable to execute the active control. For example, when the vehicle is traveling on a rough road or a road with a large undulation, the behavior of the vehicle body becomes relatively large during sudden braking, rapid acceleration, sharp cornering, or the like. Even when the behavior of the vehicle body becomes large, it is desirable to execute the active control. In the system 10, the specific resistance control is executed when the vehicle speed v detected by the vehicle speed sensor 162 is equal to or less than the threshold value v ₁ . Further, even when the vehicle speed v is equal to or less than the threshold value v ₁ , the active control is executed when it is estimated that the behavior of the vehicle body becomes relatively large. Specifically, the acceleration acting on the vehicle, that is, the longitudinal acceleration Gz _U detected by the longitudinal acceleration sensor 176 provided on the mount 24, the longitudinal acceleration Gz _L detected by the longitudinal acceleration sensor 178 provided on the lower arm 22, When either the longitudinal acceleration Gx detected by the longitudinal acceleration sensor 172 or the actual lateral acceleration Gyr actually measured by the lateral acceleration sensor 174 is equal to or greater than the respective threshold values G ₁ , G ₂ , G ₃ , G ₄ In addition, active control is executed, and in other cases, specific resistance control is executed.

If a particular resistance control is executed, as described above, so that the actuator force is the resistance of the specific size corresponding to the stroke speed V _St, details with respect to the stroke speed V _St The resistance is controlled so that the amount of current regenerated is the largest. Specifically, in the specific resistance control, the target actuator force F ^* is determined according to the following equation.
F ^* =-(C / 2) · V _St
As will be described in detail later, C is an attenuation coefficient when the energization terminals of the motor 54 are short-circuited. 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 a resistance force while regenerating the generated current to the battery 150.

  Hereinafter, it will be described in detail that the determination of the target actuator force in the specific resistance force control is performed by the above formula. FIG. 5 shows an equivalent circuit diagram of the suspension system 10. First, consider the electric power required when the actuator 26 generates the target actuator force F, that is, the consumed energy E that is the energy consumed by the resistance in the circuit. Since the consumed energy E is the product of the power supply voltage e and the energization current i flowing through the motor 54, the energization current i and the power supply voltage e are obtained in order.

Since the rotational torque Tq of the motor 54 is proportional to the energization current i, it is represented by the following equation.
Tq = K _T · i (K _T : motor constant)
The relationship between the rotational torque Tq and the actuator force F is expressed by the following equation, where L is the lead of the screw rod 50.
F = (2π / L) · Tq
From these two formulas, the energization current i is expressed by the following formula.
i = F / ψ (ψ = K _T · 2π / L) (1)

In the case of the rotational speed ω of the motor 54, if the resistance in the circuit is R, the relationship between the power supply voltage e and the energizing current i is as shown in the following equation.
i = (e−K _T · ω) / R
The relationship between the rotational speed ω and the stroke speed V _St is expressed by the following equation.
V _St = (L / 2π) · ω
From these two expressions, the power supply voltage e is expressed by the following expression.
e = R ・ i + ψ ・ V _St
Substituting equation (1) into this equation yields the following equation:
e = F · (R / ψ) + ψ · V _St (2)

Therefore, since the energy consumption E is E = e · i, it is expressed by the following equation from the equations (1) and (2).
E = F ² · (R / ψ ² ) + F · V _St (3)
Here, consider a case where the energization terminals of the motor 54 are short-circuited. In this case, since energy consumption E = 0, the actuator force F _S at the time of short-circuiting is obtained from the equation (3) as follows:
F _S = − (ψ ² / R) · V _St
Since the actuator force is proportional to the stroke speed (damper characteristics), ψ ² / R in the above equation can be said to be the damping coefficient C of the motor 54 at the time of a short circuit. Then, if the C = ψ ² / R and the damper characteristic F = −Cd · V _St (Cd: damping coefficient) are substituted into the equation (3), the following equation is obtained.
E = (Cd ² −C · Cd) · V _St ² / C (4)
Therefore, when Cd <C, the consumed energy E becomes a negative value, indicating that the current generated by the motor 54 is regenerated. When Cd = C / 2, the energy consumption E is the smallest, that is, the amount of current regenerated is the largest. From the above, from the viewpoint of power saving of the system, the target actuator force F ^* in the specific resistance control is determined by the formula F ^* = − (C / 2) · V _St.

  As described above, the suspension system 10 includes (a) vibration damping control as the first control for controlling the actuator force based on the sprung speed and the unsprung speed, and (b) generation of the actuator force exclusively for the motor. Specification as second control for generating an actuator force having a resistance of a specific magnitude in accordance with the relative motion between the sprung portion and the unsprung portion so as to be accompanied by power generation by 54 The resistance force control can be switched. In the specific resistance control, the actuator force is generated and regenerated as a resistance force that is ½ of the resistance force obtained when the current-carrying terminals of each phase of the motor 54 are short-circuited. The maximum amount of current is set. That is, the suspension system 10 is capable of efficiently regenerating the generated current and suppressing the power consumption of the system 10 by executing the specific resistance control.

≪Actuator control flow≫
The actuator 26 as described above is controlled by the actuator control program shown in the flowchart of FIG. 6 at a short time interval (for example, several milliseconds to several tens of milliseconds) while the ignition switch 160 is in the ON state. It is performed by being repeatedly executed by 142. The control flow will be briefly described below with reference to the flowchart shown in the figure. The actuator control program is executed for each actuator 26 of the spring absorber assembly 20 provided on each of the four wheels 12. In the following description, processing by this program for one actuator 26 will be described in consideration of simplification of description.

In this program, first, in step 1 (hereinafter abbreviated as “S1”, other steps are the same) and S2, it is determined whether to execute active control or specific resistance control depending on the vehicle speed v. The If the vehicle speed v is higher than the threshold speed v _1, the active control is executed. That is, in S6 to S9, in the manner previously described, the vibration damping component F _V, the roll restrain component F _R, and the pitch restrain component F _P is determined by summing them, the target actuator force F ^* Is determined. Further, when the vehicle speed v = 0, that is, when the vehicle is stopped and when the vehicle speed v is traveling at the threshold speed v ₁ or less, the specific resistance control at S10 or less is executed. However, when the vehicle speed v is traveling below the threshold speed v _1, in S3 to S5, whether the vehicle behavior is relatively large, the acceleration Gz _U acting on the vehicle, Gz _L, Gx , The actual lateral acceleration Gyr is determined based on whether or not each of the actual lateral accelerations Gyr is equal to or greater than the respective threshold values G ₁ , G ₂ , G ₃ , G ₄ . Active control is executed. It should be noted that the stroke speed V _St used in the specific resistance control is calculated in S10 based on the difference between the detected value at the previous execution of the program by the stroke sensor 164 and the detected value at this time.

A duty ratio is determined based on the target actuator force F ^* of the motor 54 determined as described above, and a control signal corresponding to the duty ratio is transmitted to the inverter 146. After the series of processes described above, one execution of the actuator control program ends.

≪Modification≫
In the suspension system of the above-described embodiment, the air spring 28 is employed as the suspension spring, but a coil spring may be employed. Further, the second control may be executed according to whether or not it is executed according to the charge amount (remaining amount) of the battery 150, that is, only when the charge amount is relatively small. Good. Furthermore, in the second control in the above embodiment, the magnitude of the behavior of the vehicle body is determined based on the longitudinal acceleration, the longitudinal acceleration, and the lateral acceleration, but may be determined based only on the longitudinal acceleration. In the second control, the magnitude of the behavior of the vehicle body is determined from the acceleration value at the current time, but the magnitude of the behavior of the vehicle body at the current time is determined from the degree of change in acceleration within a set time retroactive from the current time. May be estimated. In the second control in the above embodiment, the vehicle body posture control is not executed when the second control is executed. However, the vehicle body posture control is the first control or the second control. It may be executed regardless of whether or not.

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. FIG. 3 is a circuit diagram of a drive circuit or the like that controls an electromagnetic motor included in the actuator of FIG. 2. It is a figure which shows the relationship between the rotational speed and rotational torque of an electromagnetic motor with which the actuator of FIG. 2 is provided. 1 is an equivalent circuit diagram of a vehicle suspension system that is an embodiment of the claimable invention; FIG. It is a flowchart showing the actuator control program performed by the suspension electronic control unit shown in FIG.

Explanation of symbols

  10: Vehicle suspension system 20: Spring absorber assembly 22: Lower arm (lower part of spring) 24: Mount part (upper part of spring) 26: Actuator 28: Air spring 50: Screw rod (male thread part) 52: Nut (female thread part) 54 : Electromagnetic motor 80: Air supply / discharge device 140: Suspension electronic control unit (control device) 146: Inverter (drive circuit) 148: Converter 150: Battery

Claims (4)

Actuator which is disposed between the upper and lower springs, has an electromagnetic motor as a power source, operates in accordance with the relative movement between the upper and lower springs, and provides resistance and propulsion for the relative movement By generating force, an electromagnetic actuator that functions as a shock absorber,
A drive circuit disposed between the electromagnetic motor and the power source, driving the electromagnetic motor, and having a structure capable of regenerating the power generated by the electromagnetic motor based on the electromotive force;
A vehicle suspension system comprising: a control device that controls the actuator force by controlling the drive circuit;
The control device is
(a) a first control for controlling the actuator force based on at least one of an unsprung speed and an unsprung speed; and (b) generation of the actuator force is exclusively accompanied by power generation by the electromagnetic motor. The second control for generating the actuator force that is a resistance force of a specific magnitude corresponding to the relative motion between the upper and lower springs is configured to be switchable .
A vehicle suspension system configured to execute the first control when a traveling speed of a vehicle is higher than a set threshold value, and to execute the second control when the traveling speed is lower than the threshold value . Actuator which is disposed between the upper and lower springs, has an electromagnetic motor as a power source, operates in accordance with the relative movement between the upper and lower springs, and provides resistance and propulsion for the relative movement By generating force, an electromagnetic actuator that functions as a shock absorber,
A drive circuit disposed between the electromagnetic motor and the power source, driving the electromagnetic motor, and having a structure capable of regenerating the power generated by the electromagnetic motor based on the electromotive force;
A control device for controlling the actuator force by controlling the drive circuit;
A vehicle suspension system comprising:
The control device is
(a) a first control for controlling the actuator force based on at least one of an unsprung speed and an unsprung speed; and (b) generation of the actuator force is exclusively accompanied by power generation by the electromagnetic motor. The second control for generating the actuator force that is a resistance force of a specific magnitude corresponding to the relative motion between the upper and lower springs is configured to be switchable.
Parameter indicative of the size of the vehicle body behavior, the first control is executed, configured vehicle dual suspension system to execute the second control is smaller than the threshold is greater than the set threshold value .   3. The vehicle suspension system according to claim 1, wherein the second control is control for generating the actuator force that is a resistance force having a magnitude that maximizes a current regenerated by a power source. 4. The second control is the claims 1 to claim a control for generating the actuator force as a magnitude of the resistance force of half the drag force generated in the case of being short-circuited between the electromagnetic motor energization terminal 4. The vehicle suspension system according to any one of 3 above.

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