JP2008296802A - Suspension system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make self-diagnosis function of a suspension system practical, which comprises four solenoid type shock absorbers provided corresponding to four front/rear and left/right wheels and generating force relative to relative action of a sprung part and an unsprung part. <P>SOLUTION: Each of the solenoid type motors possessed by the four shock absorbers is constituted such that control (S10) operated so as to generate absorber force that warp force is applied to a vehicle body is executed and existence of failure of a system is determined (S11) based on behavior of the vehicle body during execution of control. Even if the warp force is applied to the vehicle body by the four shock absorber, since rigidity of the vehicle body is high and the vehicle body is not operated, according to the suspension system, even if the solenoid type motors of the four shock absorbers are operated for self-diagnosis, the vehicle body is not possibly operated if it is normal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a suspension system for a vehicle that includes an electromagnetic shock absorber that generates a force with respect to relative movement between an unsprung portion and an unsprung portion.

In recent years, as an automotive suspension system, an electromagnetic suspension system that includes an electromagnetic shock absorber that relies on the force of an electromagnetic motor to generate a force for the relative motion of the sprung and unsprung parts has been studied. For example, there is a system described in the following patent document. This electromagnetic suspension system is expected as a high-performance system because of its advantage that vibration damping characteristics based on the so-called skyhook damper theory can be easily realized.
JP 2006-168400 A

  In the system described in the above patent document, an abnormality of the system is detected by comparing the sprung acceleration estimated based on the actually detected unsprung acceleration and the actually detected sprung acceleration. Has been. When any failure occurs in the electromagnetic suspension system, the influence on the ride comfort, maneuverability, stability, etc. of the vehicle is large, and the failure occurs in the system by some means, such as the system described in the above patent document. It is strongly desired to appropriately diagnose whether or not this occurs. The present invention has been made in view of such circumstances, and an object thereof is to provide an electromagnetic suspension system having a practical self-diagnosis function.

  In order to solve the above problems, the suspension system of the present invention is provided with four electromagnetic shock absorbers corresponding to the four wheels on the front, rear, left and right, and each of the electromagnetic motors of the four shock absorbers is mounted on the vehicle body. The system is configured to execute control for generating an absorber force that causes warp force to act on the vehicle, and to determine whether the system has failed based on the behavior of the vehicle body during the execution of the control. .

  Even if a warp force is applied to the vehicle body by the four shock absorbers, the vehicle body does not operate because the vehicle body has high rigidity. Therefore, according to the suspension system of the present invention, even if the electromagnetic motors of the four shock absorbers are operated for self-diagnosis, it is possible to prevent the vehicle body from operating if normal. Due to such effects, the vehicle suspension system of the present invention is a system having a highly practical self-diagnosis function.

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 items, each of items (1) to (5) corresponds to each of items 1 to 5, and any one of items (6) and (5) 7) is limited by the technical features of claim 7 to claim 6, and any one of claims 1 to 6 is limited by the technical features of (10) to claim 7. Each corresponds.

(1) Absorbers provided corresponding to the four wheels on the front, rear, left, and right, each having an electromagnetic motor, and depending on the force of the electromagnetic motor, the force for the relative motion between the spring upper part and the spring lower part Four electromagnetic shock absorbers that generate force,
A vehicle suspension system comprising: a control device that controls the operation of each of the four shock absorbers by controlling the operation of the electromagnetic motor;
The control device is
Control is performed to operate each of the electromagnetic motors of the four shock absorbers so as to generate an absorber force that causes a warp force to act on the vehicle body, and based on the behavior of the vehicle body during the execution of the control, A vehicle suspension system including a failure determination processing unit that determines whether or not a vehicle suspension system has failed.

  The “absorber force” described in this section means not only the resistance force against the relative motion of the sprung portion and the unsprung portion but also the propulsive force. The “electromagnetic shock absorber” described later includes such a force. It is possible to adopt one that can generate “Generating an absorber force that causes a warp force to act” described in this section means that the absorber force corresponding to each of the diagonal wheels approaches the spring upper portion and the spring lower portion with the same magnitude. And the absorber force corresponding to each of the other diagonal rings is changed to the absorber force corresponding to each of the other diagonal rings. It is generated in the direction in which the sprung portion and the unsprung portion are separated from each other (hereinafter sometimes referred to as “separating direction” or “rebound direction”). Generally, since the rigidity of the vehicle body is relatively high, the warp force, which is a force that twists the vehicle body, is the distance between the sprung part and the unsprung part corresponding to the four shock absorbers (hereinafter referred to as “unsprung unsprung”). It may be generated with little variation in the distance. That is, according to the “failure determination processing unit” in the aspect of this section, the vehicle body hardly operates when the system is normal. In the system that has been studied in the past, for the self-diagnosis, the control that operates the electromagnetic motor to generate the force in the same direction to the four shock absorbers is executed, and the behavior of the shock absorber during the control is executed. Based on this, the presence or absence of system failure is determined. In such a system, the vehicle body moves up and down each time a self-diagnosis is performed, which makes the passenger feel uncomfortable. According to the aspect of this section, a system capable of performing a self-diagnosis without giving such an uncomfortable feeling to the passenger is realized.

  For example, if any of the four shock absorbers has a failure that cannot generate the target amount of absorber force (including a failure that cannot generate any absorber force), It is conceivable that the vehicle body operates, for example, the balance of the acting force is lost and the vehicle body is inclined. Therefore, for example, when it can be considered that the vehicle body operates during the above-described control, it is possible to determine that some sort of failure has occurred in the system. In addition, it is possible to allow the occupant to recognize that there is a system failure by a certain amount of movement of the vehicle body due to the system failure. Note that the “system failure” described in this section includes, for example, a disconnection of an electromagnetic motor, a malfunction such as a circuit for driving the electromagnetic motor, and a shock absorber including a screw mechanism. The failure due to excessive friction of the screw mechanism is considered. It is also possible to consider such a failure as a failure in which any of the four shock absorbers cannot generate the targeted absorber force.

  The “electromagnetic shock absorber” in the aspect of this section is not limited in its specific structure, and is not particularly limited in function. For example, in addition to the function of damping the vibration generated in the vehicle, the function of controlling the posture of the vehicle body is exhibited for the purpose of suppressing the roll, pitch, etc. of the vehicle body caused by turning, acceleration and deceleration of the vehicle. May be. The type of the “electromagnetic motor” that is the power source of the shock absorber is not particularly limited, and various types of motors such as a DC brushless motor can be adopted. Or a linear motor.

  (2) The vehicle suspension system according to (1), wherein the failure determination processing unit performs determination while the vehicle is stopped.

  Since there is no input from the outside while the vehicle is stopped, it is easy to monitor the behavior of the vehicle body during the control for applying the warp force by the failure determination processing unit. According to this aspect, it is possible to easily determine the presence or absence of a system failure based on the behavior of the vehicle body under control.

  (3) The vehicle suspension according to (1) or (2), wherein the failure determination processing unit determines that a failure has occurred in the vehicle suspension system when the vehicle body can be regarded as operating. system.

  In the aspect described in this section, for example, when the unsprung distance corresponding to at least one of the four shock absorbers fluctuates, it can be determined that a failure has occurred in the system. .

  (4) The failure determination processing unit determines whether or not there is a failure in which any of the four shock absorbers cannot generate a target absorber force. The vehicle suspension system according to any one of the items.

  (5) The vehicle suspension system according to any one of (1) to (4), wherein the failure determination processing unit determines whether or not a failure has occurred in any of the four shock absorbers. .

  The modes described in the above two sections are modes in which the content of the system failure is limited.

(6) The vehicle suspension system is
Each of the four shock absorbers is connected to the unsprung part and is connected to the unsprung part, and can be operated relative to the unsprung part unit according to the approach and separation between the unsprung part and the unsprung part. An unsprung unit, and depends on the force of the electromagnetic motor to generate a force for relative movement between the unsprung unit and the unsprung unit.
These four shock absorbers are provided correspondingly, and each is connected to one part of one of the sprung part and the unsprung part, and one part of the sprung part unit and the unsprung part unit. A spring that connects the one-side unit that is, and includes four elastic support mechanisms that elastically support the one-side unit on the one-side,
The vehicle for any one of the items (1) to (5), wherein the absorber force of each of the four shock absorbers is transmitted to the spring top and the spring bottom via the elastic support mechanism. Suspension system.

  The mode described in this section is a mode in which the elastic support mechanism is provided in series with the shock absorber. The “elastic support mechanism” in the aspect of this section can be provided mainly for the purpose of dealing with vibration of a relatively high frequency, for example. The elastic support mechanism only needs to be configured mainly with a spring, but may have a hydraulic damper described later for the purpose of assisting the spring. In addition, although what kind of structure is employable as a spring, when an elastic support mechanism has a hydraulic damper, for example, a coil spring is adopted and a hydraulic damper made into a cylinder device is used. A compact suspension system can be realized if the coil spring is arranged so as to penetrate the coil spring (for example, in the coil spring).

  Incidentally, in this specification, the term “coupled” does not only mean that they are directly connected, but also means that they are indirectly connected via some component, member, unit, or the like. For example, when the unsprung unit and unsprung unit are connected to the unsprung and unsprung units, they are directly coupled to each other, and they are coupled via a spring, a hydraulic damper, etc. The case where it is done is also included.

  (7) When the failure determination processing unit operates each of the electromagnetic motors of the four shock absorbers to generate an absorber force that causes a warp force to act on a vehicle body, the one side unit Is controlled while elastically deforming the spring with respect to the spring upper portion and the spring unsprung portion, and whether or not the vehicle suspension system has failed is determined based on the behavior of the vehicle body during the execution of the control. The vehicle suspension system according to item (6).

  In the aspect provided with the elastic support mechanism described above, even when each of the electromagnetic motors is operated so as to generate the absorber force that causes the warp force to act on the vehicle body, the sprung corresponding to the four shock absorbers There is almost no variation in the unsprung distance. However, since one side unit of the shock absorber is elastically connected to one side via an elastic support mechanism having a spring, when each of the electromagnetic motors is operated as described above, one side side The unit operates while elastically deforming the spring. Specifically, in the shock absorber corresponding to each of the diagonal wheels that generate the absorber force in the approaching direction, the other diagonal wheel that operates toward the one part and generates the absorber force in the separating direction. In the shock absorber corresponding to each of these, it moves in the direction away from one part. Therefore, in the aspect of this section, it is possible to actually operate each of the four shock absorbers when determining whether or not the system has failed. In the aspect of this section, for example, the presence or absence of a system failure can also be determined by comparing the amount of movement of the shock absorber with the amount of movement to be operated with respect to the absorber force generated at the time of this determination.

  (8) The vehicle according to (6) or (7), wherein each of the four elastic support mechanisms includes a hydraulic damper that generates a resistance force to a relative operation between the one portion and the one portion side unit. Suspension system.

  The aspect described in this section is an aspect in which the elastic support mechanism has a configuration in which a hydraulic damper is provided in parallel with the spring. The “hydraulic damper” can be provided for the purpose of assisting the spring, that is, for the purpose of dampening relatively high frequency vibrations. That is, according to the aspect of this section, it is possible to more effectively attenuate high-frequency vibration such as unsprung resonance. The structure of the hydraulic damper is not particularly limited. For example, the hydraulic damper may have a structure as a cylinder device including a housing, a piston, and the like.

  (9) The vehicle suspension system according to any one of (6) to (8), wherein the one part is an unsprung part, and the one part side unit is an unsprung part unit.

  According to the aspect described in this section, since the elastic support mechanism is arranged between the unsprung part and the unsprung side unit of the shock absorber, the shock that is input from the wheel and transmitted to the shock absorber is reduced and vibrations are generated. Can be attenuated. That is, according to the aspect of this section, the vibration transmitted to the electromagnetic motor is effectively damped, so that a highly reliable suspension system is realized.

  (10) The failure determination processing unit controls the operation of each of the electromagnetic motors of the four shock absorbers so as to vary the absorber force according to a set rule. The vehicle suspension system according to any one of the above.

  In the aspect having the elastic support mechanism described above, since one side unit of the shock absorber is actually operated at the time of determination, it is not desirable to suddenly generate the absorber force and suddenly change the one side unit. Therefore, for example, by gradually increasing the absorber force, it is possible to prevent the one-side unit from changing suddenly. Also, since the one side unit is changed by changing the absorber force, it is possible to prevent the electromagnetic motor from stopping at a specific position, thereby preventing the specific coil from generating heat. Is possible. That is, the mode described in this section is a mode that is particularly effective for the mode having the elastic support mechanism described above.

  (11) The vehicle suspension system according to (10), wherein the failure determination processing unit controls the operation of each of the electromagnetic motors of the four shock absorbers so as to periodically vary the absorber force. .

  (12) The vehicle suspension according to (11), wherein the failure determination processing unit controls the operation of each of the electromagnetic motors of the four shock absorbers so as to change the absorber force by one cycle. system.

  The modes described in the above two terms are modes in which how to change the absorber force is specifically limited.

(13) Each of the four shock absorbers is
(a) a male screw portion provided on one of the spring upper portion and the spring lower portion, and (b) a female screw portion provided on the other of the spring upper portion and the spring lower portion and engaged with the male screw portion. A screw mechanism having a structure in which the male screw portion and the female screw portion rotate relative to each other in accordance with relative movement between the spring upper portion and the spring lower portion, and the electromagnetic motor generates a force for the relative rotation. The vehicle suspension system according to any one of (1) to (12), which is configured.

  The mode described in this section is limited to shock absorbers that employ a screw mechanism. When a rotary motor is used as an electromagnetic motor, the rotational force of the motor is easily converted into a damping force for stroke operation. It becomes possible to do. 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 [Aspect of the Invention] section. can do.

<Configuration of suspension system>
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. These are arranged so as to connect them. The spring absorber assembly 20 can be roughly divided into an actuator 30 as an electromagnetic shock absorber, a hydraulic damper 32, and an air spring 34 as a suspension spring, and includes these as constituent elements. And they are integrated.

  The actuator 30 includes a ball screw mechanism including a screw rod 42 as a male screw portion in which a thread groove is formed, and a nut 44 as a female screw portion that holds the bearing ball and is screwed with the screw rod 42; An electromagnetic motor 46 (hereinafter simply referred to as “motor 46”) as a power source and a casing 48 that houses the motor 46 are provided. The casing 48 is connected to the mount portion 24 at the outer peripheral portion. The motor 46 has a hollow motor shaft 50, and the screw rod 42 is fixed to the motor shaft 50 through the inside thereof at the upper end. That is, the motor 46 applies a rotational force to the screw rod 42.

  The actuator 30 includes an outer tube 60 having an upper end fixed to the casing 48 in a state where the screw rod 42 is inserted, and a step that is fitted into the outer tube 60 and protrudes downward from the lower end of the outer tube 60. And an inner tube 62 formed in an attached shape. The nut 44 is fixed inside the upper end portion having a large diameter of the inner tube 62 in a state of being screwed with the screw rod 42. The outer tube 60 is provided with a pair of guide grooves 64 on the inner wall surface thereof so as to extend in the direction in which the axis of the actuator 30 extends (hereinafter sometimes referred to as “axial direction”). Each of a pair of keys 66 attached to the upper end portion of the inner tube 62 is fitted into each of the outer tube 60 and the inner tube 62 by the guide groove 64 and the key 66. Relative rotation is impossible and relative movement is possible in the axial direction. And the inner tube 62 is connected with the damper 32 in a lower end part.

  Although a detailed structure is omitted, the damper 32 has a structure similar to a twin tube type shock absorber. The damper 32 includes a piston rod 74 connected to a lower arm 22 through a bush 72 provided at a lower end portion of a housing 70 containing hydraulic fluid, and connected to a piston disposed in the housing 70. However, it extends from the upper side of the housing 70 and is connected to the lower end portion of the inner tube 62 at the upper end portion thereof. With such a structure, the inner tube 62 is connected to the lower arm 22 via the damper 32.

  An annular lower retainer 90 is provided on the outer periphery of the housing 70 of the damper 32. Further, the lower retainer 90 is fixed at its lower end with a carver tube 92 that houses the inner tube 62, the lower portion of the outer tube 60, and the upper portion of the damper 32. A floating member 94 is fixed to the connecting portion between the inner tube 62 and the piston rod 74. The floating member 94 includes a compression coil spring 96 disposed between the floating member 94 and the lower retainer 90, and a floating member. 94 and a compression coil spring 100 disposed between a projecting portion 98 (functioning as an upper retainer) formed inside the cover tube 92.

  The air spring 34 includes a chamber shell 120 fixed to the mount portion 24, a cover tube 92 that functions as an air piston cylinder, and a diaphragm 124 that connects them. The lid 126 of the chamber shell 120 is connected to the casing 48 of the actuator 30 via a spring support 128 having vibration-proof rubber. The lid 126 is connected to the mount 24 via an upper support 130 having vibration-proof rubber. One end of the diaphragm 124 is fixed to the lower end of the chamber shell 120 and the other end is fixed to the upper end of the cover tube 92. The pressure chamber 132 is formed by the chamber shell 120, the cover tube 92, and the diaphragm 124. A compartment is formed. The pressure chamber 132 is filled with compressed air as a fluid. From such a structure, the lower arm 22 and the mount portion 24, that is, the wheel and the vehicle body are elastically connected by the pressure of the compressed air of the air spring 34. Incidentally, the spring constant when the compression coil springs 96 and 100 described above are assumed to be one spring is set larger than the spring constant of the air spring 34.

  Due to the structure described above, the actuator 30 includes a sprung unit on the side including the screw rod 42, the motor 46, the casing 48, the outer tube 60 and the like, and is connected to the mount portion 24. The unsprung side unit connected to the lower arm 22 including 62 and the like is configured. Further, the unsprung unit and the lower arm 22 are elastically connected by an elastic support mechanism including a damper 32 and two compression coil springs 96 and 100. The damper 32 generates a resistance against relative movement between the unsprung unit and the unsprung part.

  The actuator 30 allows the screw rod 42 and the nut 44 to move relative to each other in the axial direction when the sprung portion and the unsprung portion approach or separate from each other, that is, the sprung unit and the unsprung unit can move relative to each other. In accordance with the relative movement, the screw rod 42 rotates with respect to the nut 44 (the motor shaft 50 also rotates). The motor 46 can apply a rotational torque to the screw rod 442, and the rotational torque generates a resistance force in a direction that prevents the relative movement between the unsprung unit and the unsprung unit. It is possible to make it. By making this resistance force act as a damping force with respect to the relative movement between the unsprung unit and the unsprung unit, and thus with respect to the approach / separation between the unsprung portion and the unsprung portion, the actuator 30 can function as a so-called shock absorber. It is supposed to function. The actuator 30 is also capable of generating a driving force for relative movement between the unsprung side unit and the unsprung side unit. Control based on the so-called skyhook damper theory, pseudo groundhook theory, or the like. It is possible to effectively execute the vehicle body roll at the time of turning, the vehicle body pitch at the time of acceleration / deceleration, etc., the vehicle height of the vehicle to be adjusted, and the like.

  It is as follows when paying attention to the vibration damping function in the suspension system 10 of the present embodiment. The actuator 30 can effectively dampen vibrations with a relatively low frequency of 5 Hz or less. However, effective vibration damping is difficult for vibrations having a high frequency exceeding 10 Hz. In the present embodiment, the vibration can be attenuated by the compression coil springs 96, 100 and the damper 32 with respect to the vibration in a range where the actuator 30 cannot effectively attenuate, and the frequency is high so as to exceed 10 Hz. Vibration can be effectively damped.

  As shown in FIG. 1, the suspension system 10 is a fluid inflow / outflow device for inflowing / outflowing air (air) as a fluid with respect to an air spring 34 included in each spring / absorber assembly 20. An air supply / discharge device 140 is connected to the pressure chamber 132 of the spring 34, supplies air to the pressure chamber 132, and discharges air from the pressure chamber 132. Although detailed description is omitted, the suspension system 10 is capable of adjusting the amount of air in the pressure chamber 132 of each air spring 34 by the air supply / discharge device 140. By changing the spring length of the air spring 34, it is possible to change the distance between the sprung portion and the unsprung portion of each wheel 12 (hereinafter sometimes referred to as “distance between unsprung springs”). Yes. Specifically, it is possible to increase the amount of air in the pressure chamber 132 to increase the distance between the sprung springs and decrease the amount of air to decrease the distance between the sprung springs. That is, the system 10 is capable of so-called vehicle height adjustment.

  In the suspension system 10, the operation of the spring absorber assembly 20, that is, the actuator 30 and the air spring 34 are controlled by a suspension electronic control unit 200 (hereinafter also referred to as “ECU 200”) as a control device. The ECU 200 is mainly configured by a computer including a CPU, a ROM, a RAM, and the like. The suspension ECU 200 is connected to a driver 202 as a drive circuit of the air supply / discharge device 140 and an inverter 204 as a drive circuit that is provided corresponding to the motor 46 of each actuator 30 and controls the motor 46. Has been. The driver 202 and the inverter 204 are connected to a battery 208 via a converter 206, and each control valve, pump motor, etc., and the motor 46 of each actuator 30 included in the air supply / discharge device 140 are connected to the converter 206. Power is supplied from a power source including the battery 208 and the battery 208. The inverter 204 has a structure that can regenerate the power generated by the electromotive force as a power source, and the motor 46 generates not only the motor force depending on the supply current but also the motor force depending on the electromotive force. There is a case. That is, the inverter 204 adjusts the current flowing through the motor 46, that is, the amount of current flowing through the motor 46, regardless of whether the current is supplied from the power source or the generated current caused by the electromotive force, and the motor force is The structure is controlled. The energization current amount is determined by each inverter 204 changing the ratio (duty ratio) between the pulse-on time and the pulse-off time by PWM (Pulse Width Modulation) control.

  The vehicle includes an ignition switch [I / G] 220, a vehicle speed sensor [v] 222 for detecting a vehicle traveling speed (hereinafter sometimes abbreviated as “vehicle speed”), and a sprung unsprung state for each wheel 12. Four height sensors [h] 224 for detecting the distance, vehicle height change switch [HSw] 226 operated by the driver for the vehicle height change instruction, an operation angle sensor [δ for detecting the operation angle of the steering wheel 228, a longitudinal acceleration sensor [Gx] 230 that detects actual longitudinal acceleration that is the longitudinal acceleration actually generated in the vehicle body, and a lateral acceleration sensor [Gy] 232 that detects actual lateral acceleration that is the lateral acceleration actually generated in the vehicle body , Four sprung vertical acceleration sensors [Gzs] 234 for detecting the vertical acceleration (vertical acceleration) of each mount portion 24 of the vehicle body corresponding to each wheel 12, each wheel 1 4 unsprung longitudinal acceleration sensors [Gzg] 236 for detecting the longitudinal acceleration of the vehicle, throttle sensor [Sr] 238 for detecting the opening of the accelerator throttle, brake pressure sensor [Br] 240 for detecting the master cylinder pressure of the brake, motor A resolver [θ] 242, which is a rotation angle sensor for detecting the rotation angle of 46, is provided, and these are connected to the computer of the ECU 200. The ECU 200 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. In addition, the ROM included in the computer of the ECU 200 stores a program related to the control of the actuator 30, various data, and the like.

<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 these spring absorber assemblies 20, the actuator force (which is the absorber force) of the actuator 30 is independently controlled to control the vibration of the vehicle body and the wheels 12, that is, the sprung vibration and the unsprung vibration. (Hereinafter, sometimes referred to as “vibration damping control”) is executed. 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”). First, the vibration damping component, roll suppressing component, and pitch suppressing component, which are the components of the actuator force for each of the above vibration damping control, roll suppression control, and pitch suppression control, should be added together and act between the spring top and the spring bottom. The required acting force, which is a force, is obtained, and the target actuator force is determined so that the force actually acting between the sprung portion and the unsprung portion becomes the necessary acting force. The vibration damping control, roll suppression control, and pitch suppression control are executed comprehensively by controlling the actuator 30 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 34 is used to control the vehicle height based on the driver's intention (hereinafter, “vehicle height change” for the purpose of dealing with traveling on a road with a large road surface). Is also executed). The vehicle height change control will be briefly described. The vehicle height change control is executed when a target set vehicle height that is a set vehicle height to be realized by an operation of the vehicle height change switch 166 based on the driver's intention is changed. A sprung unsprung distance as a target for each wheel 12 is set 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 height sensor 224. The operation of the air supply / exhaust device 140 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. . That is, the control is based on both the control based on the so-called skyhook damper theory and the control based on the pseudo groundhook theory. Specifically, the vertical operating speed of the vehicle body mount 24 calculated from the spring vertical acceleration detected by the spring vertical acceleration sensor 234 provided on the vehicle mount 24, the so-called sprung speed Vs. Based on the vertical movement speed of the wheel 12 calculated from the unsprung longitudinal acceleration detected by the unsprung longitudinal acceleration sensor 236 provided on the lower arm 22, so-called unsprung speed Vg, vibration damping is performed according to the following equation: The component F _V is calculated.
F _V = Cs · Vs−Cg · Vg
Here, Cs is a gain for generating a damping force in accordance with the vertical operation speed of the mount 24 of the vehicle body, and Cg generates a damping force in accordance with the vertical operation speed of the wheel 12. For gain. That is, Cs and Cg can be considered as damping coefficients for so-called sprung and unsprung absolute vibrations.

ii) Roll restraint control When the vehicle turns, the roll moment resulting from the turn causes the sprung portion on the turning inner ring side to be separated from the unsprung portion, and the sprung portion on the turning outer ring side to move closer to the unsprung portion. 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 30 on the turning inner ring side, and the actuator force in the rebound direction is applied to the actuator 30 on the turning outer ring side. Each is generated as a roll restraining force. Specifically, first, as a lateral acceleration indicating a 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 232 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 restrain 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 230, and based on the actual longitudinal acceleration Gx, the pitch restrain component F _P has the following formula Determined according to.
F _P = K ₄ · Gx (K ₄ : Gain)
Note that the pitch suppression control is executed when the throttle opening detected by the throttle sensor 238 or the master cylinder pressure detected by the brake pressure sensor 240 exceeds a set threshold.

iv) Target Actuator Force and Motor Operation Control The actuator 30 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 target actuator is a control target value in accordance with the following equation The force F ^* is determined.
F ^* = F _V + F _R + F _P
Then, the inverter 204 performs operation control of the motor 46 for generating the target actuator force F ^* determined as described above. More specifically, a target duty ratio is determined based on the target actuator force F ^* determined as described above, and a command based on the duty ratio is transmitted to the inverter 204. The inverter 204 controls the opening and closing of the switching element included in the inverter 204 under the appropriate duty ratio, and drives the motor 46 to generate the target actuator force F ^* .

v) Failure determination control The suspension system 10 has a self-diagnosis function. Specifically, the ECU 200 executes a failure determination control that is a control for determining whether or not a failure has occurred in the system, thereby performing a self-diagnosis. The failure determination control determines whether or not a system has failed while controlling each of the motors 46 of the four actuators 30 so as to generate an actuator force that causes a warp force to act on the vehicle body. . Applying a warp force to the vehicle body causes an actuator corresponding to each of the diagonal wheels to generate an actuator force of the same magnitude in the separation direction, and to an actuator corresponding to each of the other diagonal wheels, This means that a force in the approach direction is generated with the same magnitude as the actuator force corresponding to each of the one diagonal wheel. The failure determination control is executed when the vehicle is stopped and the driver is not getting on or off.

For example, as shown in FIG. 3, the actuator 30FR corresponding to the front right wheel 12FR and the rear left wheel 12RL, with a force F _W of spaced direction actuator force 30RL, the actuator corresponding to the left front wheel 12FL and the right rear wheel 12RR 30FL, consider a case where the force F _W of the approach direction of the actuator force 30RR. Even when such a warp force is applied to the vehicle body, the rigidity of the vehicle body is high, so that the posture of the vehicle body changes, that is, the distance between the sprung springs corresponding to the four wheels 12 hardly changes. However, in the spring absorber assemblies 20FR, 20RL corresponding to the right front wheel 12FR and the left rear wheel 12RL that have generated the force in the separating direction, the two springs of the compression coil springs 96, 100 are elastic against the unsprung part. The unsprung-side units connected to each other move downward while shrinking the compression coil springs 96 and 100. Further, in the spring absorber assemblies 20FL, 20RR corresponding to the left front wheel 12FL and the right rear wheel 12RR that have generated the force in the approaching direction, the unsprung side unit moves upward while extending the compression coil springs 96, 100. It will be.

  When the failure determination control is executed, if the present suspension system 10 is normal, the warp force acts on the vehicle body by the actuator force of each of the four actuators 30, and the vehicle body does not operate. However, in each of the spring absorber assemblies 20, the four actuators 30 operate so that only the unsprung side unit of the actuator 30 moves without changing the distance between the unsprung parts. That is, in the present suspension system 10, even if the actuator 30 is operated by the failure determination control, the vehicle body does not operate, and it is not necessary to give the occupant a sense of incongruity due to the vehicle body changing during self-diagnosis. It becomes.

In the failure determination control, as shown in FIG. 4, the actuator force of each of the four actuators 30 is changed in a sine wave shape, and is 1 / f (f: set frequency) for one cycle. It is made to fluctuate, that is, fluctuate according to the following equation.
F _FR = F _RL = + F ₀ · sin (2π · f · t)
F _FL = F _RR = −F ₀ · sin (2π · f · t)
For example, when a failure such as disconnection of the motor 46, malfunction of the inverter 204, sticking of the ball screw or reduction in efficiency occurs, the actuator 30 cannot generate the target actuator force, or the actuator force Is not completely generated. When each of the actuators 30 is controlled to generate the actuator force as described above, when any of the four actuators 30 cannot generate the target actuator force, The balance of the force acting on the vehicle body is lost, and the vehicle body operates. That is, in the failure determination control, when at least one of the values detected by the height sensor 224 corresponding to each of the four wheels has changed, any of the four actuators 30 is set as the target. It is determined that a failure that cannot generate the actuator force has occurred. Incidentally, the method for determining the presence or absence of a failure is not limited to the above, and other existing methods can be adopted. For example, based on the value detected by the resolver 242 included in the motor 46. It is also possible to determine. Specifically, when the difference between the rotation angle of the motor detected by the resolver 242 and the rotation angle when the actuator force having the magnitude shown in the above equation is generated is equal to or greater than a threshold value, It may be determined that a failure has occurred in the system 10. When the system 10 has a failure, the driver is made to recognize the warning lamp or the like, but the driver actually recognizes the failure by the vehicle body actually operating. It will also happen.

<Actuator control flow>
The above-described control of the actuator 26 is performed with a short time interval Δt (for example, several milliseconds to several tens of milliseconds) while the ignition switch 220 is turned on by the actuator control program shown in the flowchart of FIG. This is performed by being repeatedly executed by the ECU 200. The control flow will be briefly described below with reference to the flowchart shown in the drawing. The actuator control program is executed for each actuator 30 of the spring absorber assembly 20 provided on each of the four wheels 12. In the following explanation, processing by this program for one actuator 30 will be explained in consideration of simplification of explanation.

In the actuator control program, first, in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps), it is determined whether or not the failure determination control can be executed. Specifically, the failure determination control is executed when the requirements such as the vehicle is stopped and the driver is not getting on and off are satisfied. That is, the failure determination control is executed at the time of the initial check after the ignition switch 220 is turned on or when the vehicle stops between runs. If the failure determination control is not executed, the vibration damping component F _V , the roll suppression component F _R , and the pitch suppression component _FP are determined by the method described above in S2 and the subsequent steps. The target actuator force F ^* is determined by adding the components. Based on the determined target actuator force F ^* , the direction of the force generated by the motor 46 included in the actuator 30 and the power supplied to the motor 46 are determined. That is, the duty ratio is determined, and a control signal for the duty ratio is transmitted to the inverter 204.

When the failure determination control is executed, first, in S8, the time tc during which the failure determination control is executed is obtained by adding the program execution interval Δt to tc at the previous program execution. Next, in S9, it is determined whether or not the time tc is greater than 1 / f, which is the time for applying the warping force. When tc is within 1 / f, in S10, the actuator 30 is generated by the above-described formula F ^* = ± F ₀ · sin (2π · f · t). Then, in S11, it is determined whether or not a failure has occurred in the system 10. Specifically, when the sprung unsprung distance h detected by the height sensor 224 changes by a threshold value or more, it is determined that a failure has occurred. If a failure has occurred, in S12, the driver is made aware of the failure by turning on a warning lamp, sounding a warning buzzer, or the like. On the other hand, if tc is greater than 1 / f, the failure determination control is executed once during the stop, so that F ^* is set to 0 in S13. The elapsed time tc is set to 0 in S2 when the failure determination control is not executed due to, for example, when the vehicle starts traveling. Subsequently, a control signal based on the target actuator force F ^* determined in S 10 and S 13 is transmitted to the inverter 204. After the series of processes described above, one execution of the actuator control program ends.

  The ECU 200 that executes the actuator control program as described above generates an actuator force that causes a warp force to act on the vehicle body of each of the motors 46 of the four actuators 30 as a functional unit that executes the processes of S1, S7 to S12. And a failure determination processing unit that determines whether or not the suspension system has failed based on the behavior of the vehicle body during the execution of the control.

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 conceptual diagram which shows the warp force made to act on a vehicle body. It is a figure which shows the magnitude | size of the force which an actuator generates in the failure determination control 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.

Explanation of symbols

  10: Vehicle suspension system 20: Spring absorber assembly 22: Lower arm (lower spring) 30: Actuator (shock absorber) 32: Damper (hydraulic damper) 34: Air spring 42: Screw rod (male screw) 44: Nut (female screw) 46: Electromagnetic motor 96: Compression coil spring 100: Compression coil spring 140: Air supply / discharge device 200: Suspension electronic control unit (ECU, control device) 220: Ignition switch 224: Height sensor 242: Resolver

Claims (7)

It is provided corresponding to the front, rear, left and right four wheels, each having an electromagnetic motor, and depending on the force of the electromagnetic motor, generates an absorber force that is a force for the relative motion of the spring upper part and the spring lower part. Four electromagnetic shock absorbers,
A vehicle suspension system comprising: a control device that controls the operation of each of the four shock absorbers by controlling the operation of the electromagnetic motor;
The control device is
Control is performed to operate each of the electromagnetic motors of the four shock absorbers so as to generate an absorber force that causes a warp force to act on the vehicle body, and based on the behavior of the vehicle body during the execution of the control, A vehicle suspension system including a failure determination processing unit that determines whether or not a vehicle suspension system has failed.   The vehicle suspension system according to claim 1, wherein the failure determination processing unit makes a determination while the vehicle is stopped.   The vehicle suspension system according to claim 1 or 2, wherein the failure determination processing unit determines that a failure has occurred in the vehicle suspension system when the vehicle body can be regarded as operating.   4. The method according to claim 1, wherein the failure determination processing unit determines whether or not a failure has occurred in which any of the four shock absorbers cannot generate a target absorber force. The vehicle suspension system described.   The vehicle suspension system according to any one of claims 1 to 4, wherein the failure determination processing unit determines whether or not a failure has occurred in any of the four shock absorbers. The vehicle suspension system is
Each of the four shock absorbers is connected to the unsprung part and is connected to the unsprung part, and can be operated relative to the unsprung part unit according to the approach and separation between the unsprung part and the unsprung part. An unsprung unit, and depends on the force of the electromagnetic motor to generate a force for relative movement between the unsprung unit and the unsprung unit.
These four shock absorbers are provided correspondingly, and each is connected to one part of one of the sprung part and the unsprung part, and one part of the sprung part unit and the unsprung part unit. A spring that connects the one-side unit that is, and includes four elastic support mechanisms that elastically support the one-side unit on the one-side,
The absorber force of each of the four shock absorbers is configured to be transmitted to the sprung portion and the unsprung portion via the elastic support mechanism,
The failure determination processing unit operates each of the electromagnetic motors of the four shock absorbers so as to generate an absorber force that causes a warp force to act on a vehicle body. 2. A control for operating the spring while elastically deforming the spring and an unsprung portion is executed, and whether or not the vehicle suspension system has failed is determined based on the behavior of the vehicle body during the execution of the control. The vehicle suspension system according to any one of claims 5 to 5.   7. The failure determination processing unit controls the operation of each of the electromagnetic motors of the four shock absorbers so as to vary the absorber force according to a set rule. Vehicle suspension system.

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