JP2006015966A - Vehicular suspension control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular suspension control device capable of easily controlling the damping force according to the vehicle body mass state. <P>SOLUTION: The vehicular suspension control device 70 determines the control target value of each actuator and performs the control based on the determined control target value by correcting each control target value of a damping force changing actuator 36 when the vehicle body mass state is a standard one according to the vehicle body mass state. A means 82 is provided, which determines the correction value used for correction with the damping ratio of the rigid body vibration being substantially constant irrespective of the vehicle body mass state, and is common to each actuator 36. Since the correction value is determined regarding the vehicle body as one rigid body, an adequate correction value corresponding to the change in the vehicle body mass state can be easily determined. Further, the correction value is common to the correction of each actuator 36, and the control itself of the actuator 36 is also easy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a suspension system provided in a vehicle, and more particularly to a control device for adjusting a damping force of a suspension device provided in each wheel.

Many suspension devices have a structure in which the damping force is generated mainly by a shock absorber. In recent vehicles, many suspension devices have a structure in which the damping force is variable by an actuator. The appropriate damping force generated by the suspension device varies depending on the mass state of the vehicle body that depends on the number of passengers, the boarding position, the load amount of the load, the load position, and the like. For example, as described in the following patent document It has been studied to perform control in consideration of the vehicle body mass state using technology. In particular, Patent Document 1 and Patent Document 2 describe control based on the Skyhook theory. In this control, the damping coefficient for each of the suspension devices provided on each of the four wheels is supported by each of them. Correction is made on the basis of each of the partial masses of the vehicle body (referred to as “unsprung support load” in these documents), whereby an appropriate damping force is generated in each suspension device.
Japanese Patent Laid-Open No. 7-69025 JP-A-5-238234 Japanese Patent Laid-Open No. 5-26521

  In the techniques described in Patent Documents 1 and 2, the correction value for correcting the damping coefficient, that is, the control target value of the actuator for changing the damping force is individually determined for each actuator of the four wheels. Therefore, the control is complicated, and it is not satisfactory in terms of simplicity of control. This invention is made | formed in view of such a situation, and makes it a subject to provide the control apparatus which can perform the damping force control according to a vehicle body mass state simply.

  In order to solve the above-described problem, the vehicle suspension control device of the present invention corrects each control target value of the damping force change actuator when the vehicle body mass state is the standard state according to the vehicle body mass state, In a control device that determines a control target value for each actuator and performs control based on the determined control target value, the damping ratio of the vehicle body rigid body vibration is not dependent on the vehicle body mass state as a correction value to be used for the correction. Means for determining a correction value that is substantially constant and that is common to the actuators is provided.

  According to the suspension control device for a vehicle of the present invention, the correction value is determined so that the damping ratio of the vehicle body vibration when the vehicle body is regarded as one rigid body is substantially constant, so that the vehicle body mass state can be changed. An appropriate correction value for this can be determined easily. Further, since the correction value is common to the correction for each actuator, the control of the actuator itself becomes simple. In other words, according to the present invention, a control device that can easily perform appropriate damping force adjustment according to the vehicle body mass state is realized. Various aspects of the present invention and their functions and effects will be described in detail in the following [Aspect of the Invention] section.

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 constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following items, (1) corresponds to claim 1, (2) corresponds to claim 2, (3) corresponds to claim 3, (5) corresponds to claim 4, ( (6) corresponds to claim 5, (8) corresponds to claim 6, (9) corresponds to claim 7, and (11) corresponds to claim 8.

(1) A control device for controlling each of the damping force changing actuators provided in each of the suspension devices in order to change the damping force of each of the suspension devices provided for each of the wheels,
A standard target value determining unit that determines a standard target value that is a control target value of each of the damping force changing actuators when the vehicle body mass state is a standard state;
A vehicle body mass state related information acquisition unit for acquiring vehicle body mass state related information, which is information indicating the vehicle body mass state directly or indirectly;
Based on the vehicle body mass state related information acquired by the vehicle body mass state related information acquisition unit, each of the standard target values for correcting the standard target value so that the attenuation ratio of the vehicle body rigid body vibration becomes substantially constant regardless of the vehicle body mass state. A correction value determining unit for determining a correction value common to the suspension device;
Each control target value of the damping force changing actuator is determined based on the standard target value determined by the standard target value determination unit and the correction value determined by the correction value determination unit, and based on the control target value A suspension control device for a vehicle, comprising: an actuator control unit that controls each of the damping force changing actuators.

  The correction value determination unit included in the control device described in this section determines a correction value for correcting the standard target value. In the determination, the correction value can be determined so that the damping ratio of the vehicle body rigid body vibration, that is, the vehicle body vibration when the vehicle body is regarded as one rigid body is substantially constant regardless of the mass state of the vehicle body. If the correction value is determined according to such a process, it is possible to easily determine an appropriate correction value that can generate an appropriate damping force in each suspension device according to the vehicle body mass state. Further, since the correction value determination unit determines a correction value common to each damping force change actuator, it is possible to correct the control target value of a plurality of actuators by one correction value. The control target value of each actuator is easily determined. Therefore, according to the control device of this aspect including the correction value determining unit that determines the correction value as described above, it is possible to easily perform the appropriate damping force adjustment according to the vehicle body mass state.

  The structure of the “suspension device” for each wheel to be controlled by the control device according to the aspect of this section is not particularly limited. For example, a suspension device having a coil spring as a suspension spring (so-called “coil suspension”) The suspension device having various structures such as a suspension device called a suspension device having a gas spring as a suspension spring (a suspension device called a so-called “air suspension”) can be controlled. The mechanism for generating the damping force of each suspension device is not particularly limited, and various mechanisms including a general mechanism for generating a damping force by a suspension cylinder such as a shock absorber provided in each suspension device. Can be adopted. In addition, the “damping force changing actuator” (hereinafter sometimes simply referred to as “actuator”), which is a mechanism for changing the damping force (which may be considered as a mechanism for changing the damping coefficient), is also particularly limited. For example, one or more of various mechanisms such as a mechanism for changing the hydraulic fluid passage area of the orifice portion provided in the piston of the absorber and a mechanism for opening and closing the hydraulic fluid passage by a shutter are combined. A widely known mechanism such as such a mechanism can be employed. Various actuators such as an electromagnetic motor and an electromagnetic solenoid can be employed as the actuator drive source. For example, an actuator having a mechanism that can be controlled and operated by controlling the drive source. Can be adopted. In addition, the actuator may be capable of changing the damping force in stages, or may be able to change continuously.

  The control device according to this aspect may be any control device that can execute damping force adjustment control that is control for adjusting the damping force of each suspension device. Although a specific hardware configuration is not particularly limited, for example, an electronic control device mainly including a computer can be used. Further, the control device may be configured to select one control mode from a plurality of control modes having different control modes, and to execute the damping force adjustment control of the selected mode. Further, it may be configured to always perform the damping force adjustment control of a single control mode. Specifically, the former is, for example, as described in detail later, a plurality of controls having different control modes such as a control mode for bouncing, a control mode for pitching, and a control mode for rolling. A mode is set in which a mode is set, an appropriate control mode is selected from them according to the behavior of the vehicle, the running state, etc., and the damping force adjustment control of that mode is executed.

  The “standard target value determining unit”, which is one functional unit of the control device according to this aspect, is a part that determines a standard target value that is a control target value of the actuator when the vehicle body mass state is the standard state. The “body mass state” here is treated as one body including the body itself and the passengers who ride on the body, luggage loaded, etc. For example, the mass of the body (hereinafter referred to as “body mass”) This is a concept representing the state of mass balance, center of gravity position, sprung mass supported by each suspension system, and the like. In addition, the “standard state of the vehicle body mass state” is a specific vehicle body mass state that serves as a reference in the control. For example, the vehicle is in an empty state where no passengers, luggage, etc. exist, and only a driver with an average weight is driving. It can be set as an arbitrary state in various states such as a state of sitting on a seat. In addition, the “control target value” can be, for example, a value of a damping force state that should be generated by the cessation apparatus, for example, a value of a damping coefficient that the suspension apparatus should have. Moreover, it can also be set as the value which shows the actuator operation state (it is a concept containing an operation position etc.) which can implement | achieve the damping force state and a damping coefficient. The operating state value of the actuator varies depending on the structure of the actuator, the type of drive source it has, and the like. Specifically, for example, when a motor is provided as a drive source, values such as the rotational position of the motor, the operating position of the actuator, and the potential can be the control target value. The “standard target value” is positioned as a control target value that is the basis of control. The standard target value is determined for each actuator, but the standard target value determining unit is not limited to determining only one target value for each actuator. For example, as described above, in the case of a control device capable of executing control in a plurality of control modes, the standard target value setting unit determines a standard target value having a different value for each mode. Alternatively, by providing an actuator control unit for each functional unit that performs individual control, the control device may include a plurality of actuator control units. Further, the theory, vibration model, and the like based on which the standard target value determination unit determines the standard target value are not particularly limited. For example, various well-known methods such as skyhook damper theory, nonlinear H∞ control theory, etc. Active control theory, semi-active control theory, etc. can be widely adopted, and when control is executed in a plurality of control modes, even if those theories differ in each mode. Good.

  The “vehicle body mass state related information acquisition unit” (hereinafter sometimes simply referred to as “information acquisition unit”) included in the control device of this aspect is a functional unit that acquires vehicle body mass state related amount information. The “vehicle body mass state related information” (hereinafter sometimes simply referred to as “related information”) is information (parameter) that directly or indirectly indicates the vehicle body mass state described above. The information acquisition unit can be configured to obtain related information by performing calculation, map reference processing, and the like based on basic information that is detection values of various sensors, for example. More specifically regarding such a configuration, for example, the distance between the specific location of the vehicle body and the road surface, the distance between the vehicle body for each wheel (including the expansion and contraction length of the absorber provided in each suspension device), A sensor for detecting the pressure of the gas chamber when each suspension device has a gas spring is provided. Based on the basic information detected by these sensors, the mass of the vehicle body and the support mass of each suspension device (partial mass of the vehicle body) It is possible to obtain information that directly indicates the vehicle body mass state, such as the support mass of the front two wheels and the rear two wheels, the left two wheels, the right It is possible to obtain another information that directly indicates the vehicle body mass state such as the support mass of the two wheels and the position of the center of gravity of the vehicle body. The basic information can be considered as information indirectly indicating the vehicle body mass state, and the information acquisition unit can be configured to acquire the basic information itself as related information.

  The “correction value determination unit” included in the control device according to this aspect is a functional unit that determines the correction value based on the acquired related information. The “correction value” can be determined, for example, according to a vibration model, vibration theory, or the like when the vehicle body is regarded as one rigid body. The vibration model and the like in that case are not particularly limited. For example, it is sufficient that one correction value that can be corrected in common with the standard target value of each actuator is obtained, and various vibration models such as already known vibration models can be adopted. is there. As described above, in the case of a control device that executes control in a plurality of control modes, the correction value determination unit may adopt a vibration model or the like that is different for each control mode. That is, the correction value determination unit can be configured to determine a plurality of correction values common to the suspension devices. The correction value does not mean a narrow value such as a value that is added to or subtracted from the standard target value, but means a value that is widely used for correction processing. For example, a value that can substantially determine an appropriate control target value by multiplying / dividing the standard target value can be widely adopted. Specifically, for example, when the control target value is an attenuation coefficient or the like, a correction coefficient (also referred to as “attenuation force correction coefficient”, “gain”, or the like) multiplied by the control target value can be used as the correction value. .

  The “actuator control unit” included in the control device according to the aspect of this section is a functional unit that determines the control target value of each clutch actuator and performs actuator operation control based on the determined target value. The control target value is determined based on the standard target value and the correction value described above. The process for the determination is not particularly limited. For example, it may be a process in which a correction value common to the standard target value of each actuator is simply added, subtracted, multiplied, and divided. A process for converting the value to some other value and then correcting the value with the correction value, and a process for converting the corrected value to some other value after correcting the standard target value with the correction value For example, various processes can be employed. The actuator operation control is not particularly limited as long as it is based on the determined control target value, and various controls such as general feedforward control and feedback control are adopted. Is possible. In the case of a control device that performs control in a plurality of control modes, an actuator control unit is provided for each functional unit that performs individual control, so that the control device includes a plurality of actuator control units. May be.

  (2) The correction value determination unit calculates the correction value based on the vehicle body mass state related information acquired by the vehicle body mass state related information acquisition unit using a function based on a vibration model in which the vehicle body is regarded as one rigid body. The vehicle suspension control device according to item (1), which is to be calculated.

  The aspect described in this section is simply an aspect in which the correction value determination unit is configured to determine the correction value by simple arithmetic processing without referring to a reference database such as a map. Processing for referring to a map or the like requires a long processing time, particularly when the map is complicated. Therefore, in such a process, control with good responsiveness may not be executed. In addition, when creating map data for obtaining appropriate damping force characteristics, it is necessary to accumulate advanced technology, collect data over a long period of time, and the burden for that is large. In particular, in the case where control is executed in a plurality of control modes as described above, the above-described burden is further increased when processing such as referring to a different map for each mode is performed. In the aspect described in this section, the correction value is determined simply by calculation processing using a function. Therefore, according to the control apparatus of this aspect, simple and quick processing can be expected, and the development of the apparatus itself is also possible. It can be done easily. In the aspect of this section, the number of vibration models and functions is not limited to one. For example, when control is executed in a plurality of control modes, it is possible to adopt a different model for each control mode and a different function.

  (3) The bouncing correction value, which is the correction value used in the control over bouncing of the vehicle body, is set to be substantially constant regardless of the mass state of the vehicle body. The vehicle suspension device according to item (1) or (2), further comprising a bouncing correction value determination unit that determines in such a manner.

  The mode described in this section is a mode related to a control device capable of bouncing control. “Control over bouncing (bouncing control)” in this section is not to be interpreted in a narrow sense, but is a concept that broadly includes control for responding to bouncing behavior of the vehicle body. Specifically, it means that the control is preferably corrected by the bouncing correction value, for example, a correction value determined based on a bouncing vibration model in which the vehicle body is one rigid body.

(4) The vehicle body mass state related information acquisition unit acquires at least vehicle body mass related information as the vehicle body mass state related information,
The vehicle suspension control device according to (3), wherein the bouncing correction value determination unit determines the bouncing correction value based on vehicle body mass related information acquired by the vehicle body mass state related information acquisition unit.

  The mode described in this section is a mode in which the vehicle mass state related information that is relied upon when determining the correction value is limited in the control device that performs bouncing control. The “vehicle body mass related information” referred to in this section is a concept belonging to the lower level of the vehicle body mass state related information described above, and means information that directly or indirectly represents the vehicle body mass. Specifically, for example, information indicating directly or indirectly the support mass of each suspension device, the support mass of the two front wheels, the two rear wheels, the support mass of the left two wheels, the right two wheels, etc. Included in mass related information.

  (5) The bouncing correction value determination unit determines the bouncing correction value as a ratio value of a bouncing attenuation coefficient that is an attenuation coefficient of a rigid body vibration, and the bouncing attenuation coefficient and the vehicle body mass state in an actual vehicle body mass state The vehicle suspension control apparatus according to (3) or (4), wherein the vehicle suspension control apparatus determines the value of the ratio to the bouncing damping coefficient in a case where is in a standard state.

  The mode described in this section is a mode in which a specific value is determined as a correction value in a control device capable of bouncing control. For example, it is a bouncing vibration model in which the vehicle body is regarded as one rigid body, and is realized by determining a correction value based on a specific vibration model as shown in the following [Example]. The “bouncing damping coefficient” in the aspect of this section is a damping coefficient related to bouncing when the vehicle body is regarded as one rigid body. For example, the suspension when it is assumed that the entire vehicle body is suspended by one suspension device. It can be thought of as the attenuation coefficient generated in the device. Further, the ratio of the bouncing attenuation coefficient in the actual vehicle body mass state to the bouncing attenuation coefficient in the case where the vehicle body mass state is the standard state (hereinafter referred to as “bouncing attenuation coefficient ratio”) determined as the correction value in the aspect of this section In some cases, when the target control value is a damping coefficient that each suspension apparatus should have, a coefficient (a damping force correction coefficient of the damping force correction coefficient) is multiplied in the determination of the target control value. It is possible to use it as a kind).

  (6) The correction value determination unit determines that the pitching correction value, which is the correction value used in the control for the pitching of the vehicle body, is substantially constant regardless of the vehicle body mass state. The vehicle suspension control device according to any one of items (1) to (5), further comprising a pitching correction value determination unit that determines in such a manner.

(7) The vehicle body mass state related information acquisition unit acquires at least vehicle body mass related information and vehicle body center of gravity longitudinal position related information as the vehicle body mass state related information,
The pitching correction value determining unit determines the pitching correction value based on the vehicle body mass related information and the vehicle body center of gravity longitudinal position related information acquired by the vehicle body mass state related information acquiring unit. The vehicle suspension control device described.

  (8) The pitching correction value determining unit is configured to use the pitching correction value as a ratio value with respect to a pitching damping coefficient that is a damping coefficient of a vehicle body rigid body vibration. The suspension control device for a vehicle according to (6) or (7), wherein the ratio is determined to be a value of a ratio to a pitching damping coefficient when is in a standard state.

  The series of terms are terms showing various aspects of the control device capable of pitching control. The “control over pitching (pitching control)” in the above section is not to be interpreted in a narrow sense, but is a concept that broadly includes control for dealing with the pitching behavior of the vehicle body. Specifically, it means that the control is preferably corrected by the above pitching correction value, for example, a correction value determined based on a pitching vibration model in which the vehicle body is one rigid body. Specifically, for example, control such as dive control and squat control. Since the mode of the series of terms is the same as the mode of the series of terms related to the bouncing control, detailed description thereof is omitted here. The “pitching attenuation coefficient” in the above aspect means an attenuation coefficient related to pitching when the vehicle body is regarded as one rigid body. Further, the “vehicle center of gravity longitudinal position related information” is a concept that belongs to the lower level of the vehicle body mass state related information described above, and is information that directly or indirectly indicates the position of the vehicle body center of gravity in the longitudinal direction. . Specifically, for example, information directly or indirectly indicating the relationship between the distance between the center of gravity of the vehicle body and the front wheel axis or the rear wheel axis, the two front wheels, or the support mass supported by the two rear wheels, and the like. It is included in the position related information in the longitudinal direction of the center of gravity.

  (9) The correction value determination unit determines that the rolling correction value, which is the correction value used in control of rolling of the vehicle body, is substantially constant regardless of the vehicle body mass state. The vehicle suspension control device according to any one of items (1) to (8), further comprising a rolling correction value determination unit that determines to be

(10) The vehicle body mass state related state acquisition unit acquires at least vehicle body mass related information as the vehicle body mass state related information,
The vehicle suspension control apparatus according to (9), wherein the rolling correction value determination unit determines the rolling correction value based on the vehicle body mass related information acquired by the vehicle body mass state related information acquisition unit.

  (11) The rolling correction value determining unit may determine the rolling correction value as a ratio value of a rolling damping coefficient that is a damping coefficient of a rigid body vibration, and a rolling damping coefficient and a body mass state in an actual body mass state. The vehicle suspension control device according to item (9) or (10), wherein the vehicle suspension control device is determined to be a value of a ratio to a rolling damping coefficient in a case where is in a standard state.

  The series of terms are terms showing various aspects of the control device capable of rolling control. The “control over rolling (rolling control)” in the above section is not to be interpreted in a narrow sense, but is a concept that broadly includes control for responding to the rolling behavior of the vehicle body. Specifically, it means that the control is preferably corrected by the rolling correction value, for example, a correction value determined based on a rolling vibration model in which the vehicle body is one rigid body. Since the mode of the series of terms is the same as the mode of the series of terms related to the bouncing control, detailed description thereof is omitted here. The “rolling damping coefficient” in the above aspect means a damping coefficient related to rolling when the vehicle body is regarded as one rigid body.

  The three controls for bouncing, pitching, and rolling have been described above. However, the control device that can be an aspect of the claimable invention may be a control device that executes only one of the three controls. In addition, a control device that can execute any two or more of the three controls and select and execute one of the two or more controls may be used. Specifically, for example, the latter control device is used for control from among two or more of the bouncing correction value, the pitching correction value, and the rolling correction value in accordance with the control executed by the control device. The embodiment may include a correction value selection unit that selects one correction value, and a bouncing correction value determination unit, a pitching correction value determination unit, and a rolling according to control executed by the control device. It can be set as the thing provided with the correction value determination part selection part which selects one correction value determination part to perform among any two or more of the correction value determination parts. In the latter control device, in particular, a control device capable of executing three controls, more appropriate control is executed with respect to the adjustment of the damping force corresponding to the change in the vehicle body mass state.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, first, a vibration model that is a basis for determining a correction value in the vehicle suspension control device of the embodiment, and a function used for determining a correction value derived from the model will be described. Thereafter, the overall configuration of the suspension system including the suspension device to be controlled by the control device, the control mode in the damping force adjustment control, the damping force adjustment control by the control device, the functional configuration of the control device, A description will be given in order. It should be noted that the present invention is not limited to the following examples, and in addition to the following examples, various modifications can be made based on the knowledge of those skilled in the art, including the aspects described in the above [Aspect of the Invention] section. The present invention can be carried out in various modes with improvements.

<Vibration model that is the basis for correction value determination and function used for correction value determination>
In the present embodiment, the correction value for correcting the standard target value is calculated using a function derived from a vibration model in which the vehicle body is regarded as one rigid body (hereinafter sometimes referred to as “correction value determination function”). The In the present embodiment, the control device executes three controls, bouncing control, pitching control, and rolling control. In each control, the vibration models on which the correction value determination function depends are different from each other. Hereinafter, the vibration model and the correction value determination function in each control will be described in order.

(A) Bouncing Control FIG. 1A shows a conceptual diagram of a vibration model that relies on determining a correction value in bouncing control. As can be seen from the figure, this vibration model regards the vehicle body 10 as one rigid body, and the vehicle body is suspended by one suspension device 20 (configured by one spring 22 and one damper 24). This is a simplified vibration model. In the figure, M represents the mass of the vehicle body, X represents the amount of vertical displacement of the vehicle body 10, K represents the spring constant of the spring 22, and C represents the damping coefficient of the damper 24.

Since the model of FIG. 1A is specialized for bouncing control, if the spring constant K of the spring 22 is the bouncing spring constant K _B and the damping coefficient C of the damper 24 is the bouncing damping coefficient C _B , The equation of motion in that model is
M · X ″ + C _B · X ′ + K _B · X = 0 (1)
X ″ + 2 · ζ _B · ω _B · X ′ + ω _B ² · X = 0 (2)
It can be expressed as. Here, X ′ is a displacement speed, X ″ is a displacement acceleration, ζ _B is a bouncing damping ratio, ω _B is a parameter for determining bouncing resonance (ω _B / 2π is a resonance frequency),
ζ _B = C _B / {2 · (M · K _B ) ^1/2 } (3)
ω _B = (K _B / M) ^1/2 (4)
Is established.

In the bouncing control based on the vibration model, if the bouncing damping ratio ζ _B is constant, the same damping characteristics can be obtained even when the vehicle body mass M is different. Therefore, under the condition that the bouncing damping ratio ζ _B is constant, the vehicle body mass (standard vehicle body mass) in the standard state is M ₀ , and the vehicle body mass in a specific state different from the standard state is M _1. the spring constant K _B0, if the bouncing spring constant in a particular state K _B1, ratio bouncing damping coefficient C _B0 in the standard state for bouncing damping coefficient C _B1 at a particular state (hereinafter, referred to as "bouncing damping coefficient ratio" )
C _B1 / C _B0 = {(M ₁ / M ₀ ) · (K _B1 / K _B0 )} ^1/2 (5)
It becomes.

Here, if the suspension spring of the suspension device is a coil spring, that is, a vehicle equipped with a coil suspension,
K _B1 / K _B0 = 1 (6)
Therefore, the bouncing attenuation coefficient ratio is
C _B1 / C _B0 = (M ₁ / M ₀ ) ^1/2 = α ^1/2 (7)
It becomes. Incidentally, α is a vehicle body mass ratio and is defined as α = M ₁ / M ₀ . In addition, when the suspension spring of the suspension device is a gas spring, that is, in the case of a vehicle equipped with an air suspension,
K _B / M = cont. (8)
Therefore, the attenuation coefficient ratio is
C _B1 / C _B0 = α (9)
It becomes. That is, since M ₀ is known, if M ₁ is obtained, the bouncing attenuation coefficient ratio (C _B1 / C _B0 ) can be obtained.

Therefore, in the bouncing control that relies on the vibration model, when the vehicle body mass changes, the bouncing damping coefficient ratio (C _B1 / C _B0 ) is used as a correction coefficient, that is, a bouncing correction value. By determining the target control value of each suspension device based on the standard target of each suspension device, it is possible to adjust the damping force appropriately. More specifically, for example, when the control target value is a damping coefficient that should be possessed in each suspension device, the correction value is multiplied by the standard target damping coefficient as the standard target value of each suspension device. The target damping coefficient that is the control target value may be determined.

(B) Pitching control FIG. 1B shows a conceptual diagram of a vibration model that relies on determining correction values in pitching control. As can be seen from the figure, this vibration model regards the vehicle body 10 as one rigid body, and each of the front wheel side and the rear wheel side of the vehicle body has one front suspension device 20f and one rear suspension device 20r (one each). The vibration model is assumed to be suspended by a front spring 22f, a rear spring 22r, and one front damper 24f and a rear damper 24r, and is a simplified vibration model. In the figure, part mass M _f of the front wheel support mass is a partial mass that is supported by the front wheels of the vehicle mass M (front-wheel side sprung mass), M _r is supported by rear wheel of the vehicle mass M the wheel support mass (rear wheel side sprung mass) after it, X _f is the vertical displacement of the part which is supported on a vehicle body of the front suspension device 22f (the front vertical displacement), X _r is the rear side of the vehicle body distance vertical displacement amount of the portion is supported by the suspension device 22r (the rear vertical displacement), it represents respectively, G is a vehicle body centroid, is L _f from the front wheel axis of the vehicle body front-rear direction of the vehicle body gravity center G pairs wheel gravity center distance is, L _r is the distance a is to rear wheel center of gravity distance from the rear wheel axis of the vehicle body front-rear direction of the vehicle body gravity center G, the theta _P pitching angle, respectively. Each of K _f and K _r represents a spring constant of each of the springs 22f and 22r, and each of C _f and C _r represents a damping coefficient of each of the dampers 24f and 24r.

The equation of motion in the model of FIG.
I _P · θ _P "+ C _P · θ _P '+ K _P · θ _P = 0 (10)
θ _P ”+ 2 · ζ _P · ω _P · θ _P '+ ω _P ² · θ _P = 0 (11)
It is expressed. Here, θ _P ′ is the pitching angular velocity, θ _P ″ is the pitching angular acceleration, I _P is the pitching moment of inertia, C _P is the pitching damping coefficient, and K _P is the pitching stiffness,
X _f = −θ _P · L _f (12)
X _r = θ _P · L _r (13)
Can be regarded as
I _P = M _f · L _f ² + M _f · L _f ² (14)
C _P = C _f · L _f ² + C _r · L _r ² (15)
K _P = K _f · L _f ² + K _r · L _r ² (16)
It is related to Further, ζ _P is a pitching attenuation ratio, ω _P is a parameter for determining pitching resonance (ω _P / 2π is a resonance frequency), and
ζ _P = C _P / {2 (I _P · K _P ) ^1/2 } (17)
ω _P = (K _P / I _P ) ^1/2 (18)
Is established.

In the pitching control based on the vibration model, if the pitching damping ratio ζ _P is constant, the vehicle body mass state, specifically, the front wheel support mass M _f , the rear wheel support mass M _f , the front wheel center of gravity distance L _f , and the rear wheel Even if the center-of-gravity distance L _r is different, the same attenuation characteristic can be obtained. Therefore, under the condition that the pitching damping ratio ζ _P is constant, the pitching inertia moment in the standard state is I _P0 , the pitching inertia moment in a specific state different from the standard state is I _P1, and the pitching stiffness in the standard state is K _P0, if the pitching stiffness in a particular state K _P1, the ratio of pitch damping coefficient C _P0 at standard conditions for pitching damping coefficient C _P1 at a particular state (hereinafter, referred to as "pitching damping coefficient ratio") is,
C _P1 / C _P0 = {(I _P1 / I _P0 ) · (K _P1 / K _P0 )} ^1/2 (19)
It becomes. On the other hand, if you follow the model,
I _P1 / I _P0 = (M _f1 · L _f1 ) / (M _f0 · L _f0 ) = α _f · β _f (20)
I _P1 / I _P0 = (M _r1 · L _r1 ) / (M _r0 · L _r0 ) = α _r · β _r (21)
Is established. Incidentally, each of M _f0 and M _f1 is a front wheel support mass in the standard state and the specific state, and each of M _r0 and M _r1 is a rear wheel support mass in the standard state and the specific state, and L _f0 , Each of L _f1 is a front wheel center-of-gravity distance in each of the standard state and the specific state, and each of L _r0 and L _r1 is a center of gravity distance of the rear wheel in each of the standard state and the specific state. Α _f and α _r are the front vehicle body mass ratio and the rear vehicle body mass ratio, respectively, which are defined as α _f = M _f1 / M _f0 and α _r = M _r1 / M _r0 , respectively. , Β _f , β _r are the front wheel center of gravity distance ratio and the counter wheel center of gravity distance ratio, respectively, and are defined as β _f = L _f1 / L _f0 and β _r = L _r1 / L _r0 , respectively. . If you follow the model,
K _P1 / K _P0 = (K _f1 · L _f1 ² + K _r1 · L _r1 ² ) / (K _f0 · L _f0 ² + K _r0 · L _r0 ² )
(22)
That is,
K _P1 / K _P0 = A · α _f ² · β _f ² (23)
K _P1 / K _P0 = A · α _r ² · β _r ² (24)
Is established. Incidentally, K _f0 and K _f1 are spring constants in the standard state and the specific state of the front spring 22f, and K _r0 and K _r1 are spring constants in the standard state and the specific state of the rear spring 22r. A is expressed by the following equation.
A = (K _f1 / M _f1 ² + K _r1 / M _r1 ² ) / (K _f0 / M _f0 ² + K _r0 / M _r0 ² )
... (25)
From the above, the pitching attenuation coefficient ratio is
C _P1 / C _P0 = A ^1/2 · α _f ^3/2 · β _f ^3/2 (26)
C _P1 / C _P0 = A ^1/2 · α _r ^3/2 · β _r ^3/2 (27)
It becomes.

Here, in the case of a car equipped with a coil suspension,
K _f0 = K _f1 (28)
K _r0 = K _r1 (29)
Is established. That is, since K _f0 , K _r0 and M _f0 , M _r0 are known, the pitching attenuation coefficient ratio (C _P1 / C _P0 ) can be calculated by obtaining M _f1 and M _r1 . In addition, in the case of a vehicle equipped with an air suspension,
K _f0 / M _f0 = K _f1 / M _f1 (30)
K _r0 / M _r0 = K _r1 / M _r1 (31)
Is established. In other words, since K _f0 / M _f0 and K _r0 / M _r0 are known, similarly, if M _f1 and M _r1 are acquired, the pitching attenuation coefficient ratio (C _P1 / C _P0 ) can be calculated. Is possible.

Therefore, in the pitching control based on the vibration model, when at least one of the front wheel support mass, the rear wheel support mass, and the position of the center of gravity of the vehicle body in the front-rear direction fluctuates, the pitching damping coefficient ratio (C _P1 / C _P0 ) is used as a correction coefficient, that is, a pitching correction value, and the target control value of each suspension device is determined based on the correction value and the standard target of each suspension device, thereby enabling appropriate damping force adjustment. Become. More specifically, for example, when the control target value is a damping coefficient that each suspension apparatus should have, the correction value is multiplied by the standard target damping coefficient that is the standard target value of each suspension apparatus. The target damping coefficient that is the control target value may be determined.

<Rolling control>
Although illustration of the vibration model is omitted, also in rolling control, the vehicle body is handled as one rigid body as in the case of the above two controls. Assuming that the rolling angle is θ _R , the rolling angular velocity is θ _R ′, and the rolling angular acceleration is θ _R ″, as in the pitching model, the equation of motion in the rolling model is
I _R · θ _R "+ C _R · θ _R '+ K _R · θ _R = 0 (32)
θ _R ″ + 2 · ζ _R · ω _R · θ _R '+ ω _R ² · θ _R = 0 (33)
It is expressed. Here, I _R is the rolling inertia moment, C _R is the rolling damping coefficient, and K _R is the rolling stiffness. Ζ _R is a rolling damping ratio, ω _R is a parameter for determining rolling resonance (ω _R / 2π is a resonance frequency), and
ζ _R = C _R / {2 (I _R · K _R ) ^1/2 } (34)
ω _R = (K _R / I _R ) ^1/2 (35)
Is established.

In the rolling control based on the vibration model, if the rolling damping ratio ζ _R is constant, the same damping characteristic can be obtained even when the vehicle body mass state is different. Therefore, under the condition that the rolling damping ratio ζ _R is constant, the rolling inertia moment in the standard state is I _R0 , the pitching inertia moment in a specific state different from the standard state is I _R1, and the rolling stiffness in the standard state is K _R0, when the rolling rigidity in a particular state K _R1, ratio rolling damping coefficient C _R0 at standard conditions for a rolling damping coefficient C _R1 in a specific state (hereinafter, referred to as "rolling damping coefficient ratio") is, pitching model As in
C _R1 / C _R0 = {(I _R1 / I _R0 ) · (K _R1 / K _R0 )} ^1/2 (36)
It becomes. On the other hand, unlike the pitching model, if it is considered that the lateral displacement of the center of gravity G is small even by rolling,
I _R1 / I _R0 = M ₁ / M ₀ = α (37)
Is established. Incidentally, each of M ₀ and M ₁ is the standard vehicle body mass and the vehicle body mass in a specific state, and α is the vehicle body mass ratio described above.

In an actual vehicle, the front wheel side suspension device and the rear wheel side suspension device generally have different spring constants. In view of this, the front wheel side suspension device in the standard state and the specific state is used. The spring constants of the rear wheel side suspension device in the standard state and the specific state are respectively K _r0 and K _r1 , respectively, and the front wheel side tread is Tr _f and the rear spring constant of K _f0 and K _f1. If the tread on the wheel side is Tr _r ,
K _R1 / K _R0
= {(K _f1 + K _r1 ) · (Tr _f / 2) ² · 2} / {(K _f0 + K _r0 ) · (Tr _r / 2) ² · 2
... (38)
It becomes. In general, the tread Tr _f on the front wheel side and the tread Tr _r on the rear wheel side can be considered to be substantially equal.
K _R1 / K _R0 = (K _f1 + K _r1 ) / (K _f0 + K _r0 ) (39)
It becomes. In addition, the front wheel support masses in the standard state and the specific state are M _f0 and M _f1 , respectively, and the rear wheel support masses in the standard state and the specific state are M _r0 and M _r1 , respectively.
F _f0 = K _f0 / M _f0 (40)
F _f1 = K _f1 / M _f1 (41)
F _r0 = K _r0 / M _r0 (42)
F _r1 = K _r1 / M _r1 (43)
If the above equation is
K _R1 / K _R0 = (F _f1 · M _f1 + F _r1 · M _r1 ) / (F _f0 · M _f0 + F _r0 · M _r0 )
... (44)
It becomes.

For cars with coil suspension,
K _R1 / K _R0 = 1 (45)
Therefore, the rolling damping coefficient ratio (C _R1 / C _R0 ) is
C _R1 / C _R0 = α ^1/2 (46)
Since M ₀ is known, if M ₁ is obtained, the rolling attenuation coefficient ratio (C _R1 / C _R0 ) can be calculated.

In addition, in the case of a vehicle equipped with an air suspension,
F _f0 = F _f1 (47)
F _r0 = F _r1 (48)
(K _R1 / K _R0 ) is
K _R1 / K _R0 = (F _f0 · M _f1 + F _r0 · M _r1 ) / (F _f0 · M _f0 + F _r0 · M _r0 )
... (49)
And
B = (F _f0 · M _f1 + F _r0 · M _r1 ) / (F _f0 · M _f0 + F _r0 · M _r0 ) (50)
Then, the rolling damping coefficient ratio (C _R1 / C _R0 ) is
C _R1 / C _R0 = (α · B) ^1/2 (51)
It becomes. Further, since K _f0 , K _r0 , M _f0 , and M _r0 are known, F _f0 and F _r0 are known, and if M _f1 and M _r1 are obtained, the value of B can be calculated. Further, since the known M _f0 and M _r0 to M ₀ and the acquired M _f1 and M _r1 to M ₁ are respectively obtained and α can be calculated, the rolling attenuation coefficient ratio (C _R1 / C _R0 ) can be calculated. It is.

Therefore, in the rolling control based on the vibration model, when at least one of the front wheel support mass and the rear wheel support mass fluctuates, the rolling damping coefficient ratio (C _R1 / C _R0 ) is set as a correction coefficient, By using the rolling correction value and determining the target control value of each suspension device based on the correction value and the standard target of each suspension device, the appropriate damping force can be adjusted. More specifically, for example, when the control target value is a damping coefficient that each suspension apparatus should have, the control target value is determined by multiplying the correction value by the standard target value of each suspension apparatus. You can do it.

<Configuration of vehicle suspension system>
FIG. 2 shows a hardware configuration of the entire vehicle suspension system controlled by the suspension control device of this embodiment, and a block diagram of a portion deeply related to the damping force adjustment control performed by the control device in the hardware configuration, As shown in FIG. Hereinafter, the configuration of the present suspension system will be described with reference to these drawings.

  This suspension system is a four-wheel independent suspension type suspension system, and an air suspension device 34 mainly including a suspension cylinder 32 is provided for each wheel 30. The suspension cylinder 32 is a pneumatic cylinder and has a general structure including a shock absorber, an air chamber for containing gas, and the like. Each suspension cylinder 32 is provided with a damping force changing actuator (hereinafter sometimes simply referred to as “actuator”) 36 using an electromagnetic motor as a drive source at the upper portion, and the actuator 36 is a control that is inserted into the absorber rod. By rotating the rod, a damping force changing valve provided in the absorber is operated. The damping force generated in each suspension cylinder 32 is changed by operating the valve. Incidentally, the valve is variable in a plurality of stages (for example, 9 stages), and the damping force of each suspension cylinder 32 is switched to a plurality of stages by the actuator 36. Each suspension cylinder 32 can change the amount of gas stored in the air chamber, and the height of the supported portion of the vehicle body supported by each suspension device 34 is changed by changing the amount of gas. It is possible. That is, this suspension system has a vehicle height adjustment function. As devices for adjusting the vehicle height, a compressor 38, a front wheel side height control valve 40, a rear wheel side height control valve 42, a height control switch 44, and the like are provided.

  This suspension system has various sensors for detecting various information related to the vehicle such as the vehicle running state. If these various sensors are described sequentially, the two front wheels are provided with wheel speed sensors 50 for detecting the wheel rotation speed, which is basic information of the vehicle traveling speed. A height control sensor 52 for detecting the height position of the supported portion of the vehicle body is provided. Each of the height control sensors 52 includes a G sensor for detecting the vertical displacement acceleration of each supported portion. Further, each suspension cylinder 32 has a gas pressure for detecting an air pressure in the air chamber, which is basic information on a partial mass of the vehicle body supported by each suspension device 34 (sometimes referred to as “support load”). A sensor 54 is provided. Furthermore, a stop lamp switch 56 for detecting the presence or absence of a brake operation, a steering angle sensor 58 for detecting the steering angle of the steering wheel, and a door courtesy switch 60 for detecting the open / closed state of each door, Is provided.

  This suspension system includes a suspension electronic control unit (hereinafter also referred to as “suspension ECU” or simply “ECU”) 70 as a suspension control device for controlling itself. The ECU 70 mainly includes a computer including a CPU, a ROM, a RAM, a bus, an I / O, and the like, and includes a drive circuit (driver) for each of various hard devices. For example, with regard to a device deeply related to damping force adjustment control, each of the damping force changing actuators 36 is connected to a computer I / O via a separate drive circuit for each of the actuators 36. The I / O is also connected to the sensor and the like, and the ECU 70 can obtain various information related to the vehicle when performing damping force adjustment control. An engine electronic control unit (engine ECU) 72 is also connected to the I / O in order to acquire information related to the acceleration state of the vehicle. Incidentally, information on damping force control is displayed on a combination meter 74 provided on the instrument panel.

<Control mode executed by vehicle suspension control device>
The suspension ECU 70, which is the suspension control device of the present embodiment, selectively executes the following five modes of damping force adjustment control according to the traveling state of the vehicle.
a) tilt control b) sway sensitive control c) anti-dive control d) anti-squat control e) anti-roll control

  Each of the above controls is performed by individually controlling the damping force changing actuators 36 of the respective suspension cylinders 32. In the following, each control will be briefly described. The “tilting control” is a control performed so that an appropriate damping force characteristic can be obtained with respect to a relatively large road surface unevenness. The control is to reduce the feeling of feeling at the time of traveling on a rough road surface, etc., and to ensure a comfortable ride and to realize a flat feeling of the vehicle body by setting the generated damping force to a relatively low value. In addition, “anti-dive control” is a control for slowing down the dive speed in the dive state of the vehicle body that occurs when the vehicle is decelerated, and ensuring maneuverability and stability. “Anti-squat control” is generated during vehicle acceleration. This is a control for slowing the squat speed in the squat state of the vehicle body to ensure maneuverability and stability. Furthermore, “anti-roll control” is a control to ensure steering performance and stability by optimizing the damping force according to the state at the time of steering, relaxing the roll speed in the roll state of the vehicle body that occurs during turning. is there. As will be described in detail later, the ECU 70 determines in which control mode the control should be performed based on the running state of the vehicle, and the control target of the actuator according to the process set for the determined control mode. The value is determined and the damping force is adjusted based on the target value.

In this embodiment, the damping force adjustment control in the above five modes is divided into the following three upper control modes.
A) Bouncing control B) Pitching control C) Rolling control Specifically speaking, tilt control and sway sensitive control are "bouncing control", anti-dive control and anti-squat control are "pitching control", and anti-roll control is " Each of them is included in the “rolling control”. As will be described in detail later, in determining the control target value, first, a standard target value when the vehicle body mass state is the standard state is determined, and the standard target value is corrected by a predetermined correction value corresponding to the vehicle body mass state. Done. The correction value used for the correction is determined for each of the above three upper control modes, and the correction value in each of the five control modes is the correction value determined for each upper control mode to which each belongs. Will be adopted.

<Damping force adjustment control by vehicle suspension control device>
The damping force adjustment control by the ECU 70 which is the suspension control device of the present embodiment is performed by executing a damping force adjustment control program whose flowchart is shown in FIG. The control program is stored in a ROM of a computer included in the ECU 70, and is repeatedly executed after a short time interval (for example, 10 to several tens of msec) after the ignition switch of the vehicle is turned on. The actual process of damping force adjustment control in this suspension system will be described below with reference to the flowchart of FIG.

  In the damping force adjustment control, first, in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps), it is determined whether or not the vehicle body mass condition is being obtained. In this embodiment, there are two conditions for obtaining the vehicle body mass state: (1) that all the doors of the vehicle are closed, and (2) that the vehicle is not in the running state. In this case, it is determined that the vehicle body mass state can be acquired. In other words, the process of this step is a process for obtaining the current vehicle body mass state in a state where there is no passenger getting on or off of the vehicle or loading or unloading of luggage and the vehicle is stationary. It is. Whether the vehicle door is opened or closed is determined based on a detection signal from the door courtesy switch 60, and whether or not the vehicle is in a running state is determined based on a detection signal from the wheel speed sensor 30. In S1, when it is determined that the vehicle state satisfies the vehicle body mass state acquisition condition, the next process for determining the correction value in S2 is performed, and when it is determined that the vehicle is not satisfied, The process of S2 is skipped.

  The process for determining the correction value in S2 is performed by executing a correction value determination routine shown in the flowchart of FIG. In the process for determining the correction value, first, in S21, the gas pressure in the air chamber of each suspension cylinder 32 is acquired as basic information. This gas pressure is acquired based on a detection signal of a gas pressure sensor 54 provided in each suspension cylinder 32. Subsequently, in S22, the partial mass of the vehicle body supported by each suspension device 34, that is, the support mass of each suspension device 34 is acquired. Specifically, in the ROM, the relationship between the gas pressure and the support mass for each suspension device 34 is stored as known data in the form of a map, and the gas acquired with reference to the map is stored. Processing for determining the support mass of each suspension device 34 at the pressure is performed.

Next, in S23, based on the acquired support mass of each wheel, the current vehicle body mass M ₁ , front wheel support mass M _f1 , rear wheel support mass M _r1 , front wheel center of gravity distance L _f1 (or rear wheel) The center of gravity distance L _r1 ) is calculated. This calculation follows a simple arithmetic operation, and a specific description of the calculation formula is omitted here. As a result of the processing of S21 to S23, vehicle body mass state related information, more specifically, vehicle body mass related information and vehicle body center-of-gravity longitudinal position related information are acquired.

In subsequent S24, a bouncing correction value that is a correction value used in bouncing control is calculated. In this embodiment, the bouncing correction value is the bouncing attenuation coefficient ratio (C _B1 / C _B0 ) described above. Since the suspension device 34 is a so-called air suspension, the bouncing damping coefficient ratio is calculated based on the above-described equation (9) that is a correction value determination function. For this calculation, the value of the current vehicle body mass M ₁ acquired previously is used. It should be noted that the value of the vehicle body mass M ₀ in the standard state required for this calculation is stored in the ROM as known data.

In subsequent S25, a pitching correction value that is a correction value used in the pitching control is calculated. In this embodiment, the pitching correction value is the pitching attenuation coefficient ratio (C _P1 / C _P0 ) described above. Considering that the suspension device 34 is a so-called air suspension, the pitching damping coefficient ratio is calculated based on the equation (26) (or equation (27)) which is a correction value determination function. For this calculation, the previously acquired front wheel support mass M _f1 , rear wheel support mass M _r1 , and front wheel center of gravity distance L _f1 (or rear wheel center of gravity distance L _r1 ) are used. It should be _noted that the front wheel support mass M _f1 , rear wheel support mass M _r1 , front wheel center of gravity distance L _f1 (or rear wheel center of gravity distance L _r1 ), spring constant K _f0 , K The value of _r0 is stored in the ROM as known data.

In the next S26, rolling correction, which is a correction value used in rolling control, is calculated. In this embodiment, the rolling correction value is the rolling attenuation coefficient ratio (C _R1 / C _R0 ) described above. Since the suspension device 34 is an air suspension, the rolling damping coefficient ratio is calculated based on the aforementioned equation (51) that is a correction value determination function. For this calculation, the vehicle body mass M ₁ , the front wheel support mass M _f1 , and the rear wheel support mass M _r1 obtained at the present time are used. The values of the vehicle body mass M ₀ , the front wheel support mass M _f0 , the rear wheel support mass M _r1 , the spring constants K _f0 and K _r0 in the standard state required in this calculation are stored in the ROM as known data. ing.

  By the processes of S24 to S26, three correction values are calculated, which are common correction values that are relied upon in determining the control target value for each suspension device 32. Then, the three correction values calculated by the processes of S24 to S26 are updated by being stored in the RAM of the computer of the ECU 70. Note that S24 to S26 are processing in the case of a so-called air suspension vehicle, but in the case of a coil suspension vehicle, the above-described equations (7) and (26) (or equation (27)), respectively. Based on equation (46), three attenuation coefficient ratios that are correction values for each control may be calculated. In S21 and S22, the vehicle body mass state-related information is acquired based on the gas pressure in the chamber based on the fact that the vehicle is an air suspension equipped vehicle. On the other hand, when the vehicle is a vehicle equipped with a coil suspension, for example, sensors similar to the height control sensors 40 and 42 described above are provided, and each suspension device 34 detected by these sensors or the like is provided. Based on the height position of each supported part, it is also possible to obtain the vehicle body mass state related information described above.

  After the correction value determination process of S2 is completed or after the process is skipped, the control mode determination process of S3 to S6 is executed. In this control mode determination process, first, in S3, it is determined whether or not the vehicle body should perform the pitching control mode control. Specifically, it is determined whether or not a dive state (a state where a dive or a dive is about to be performed) or a squat state (a state where a squat is likely to be a squat). Specifically, it is determined that the brake operation is being performed based on the signal from the stop lamp switch 56, and the vehicle deceleration is determined to be greater than or equal to a predetermined value based on the detection signal from the wheel speed sensor 50. In this case, it is determined that the vehicle is in the dive state, the engine is determined to be equal to or higher than the predetermined number of revolutions based on information from the engine ECU 72, and the vehicle acceleration is determined based on the detection signal of the wheel speed sensor 50 When it is determined that the value is equal to or greater than the predetermined value, the squat state is determined. If it is determined in S3 that the vehicle is in the dive state or squat state, that is, if it is determined that the pitching control should be performed, it is determined in S4 whether or not the anti-dive control should be performed. When in the dive state, the control mode is determined as anti-dive control, and when in the squat state, the control mode is determined as anti-squat control.

  If it is determined in S4 that the pitching control mode should not be controlled, it is determined in S5 whether or not the rolling control mode should be controlled. Specifically, it is determined whether or not the vehicle body is in a rolled state (a state in which the vehicle body is being rolled or is about to roll). Specifically, it is in a roll state when a predetermined yaw rate is generated based on the vehicle traveling speed based on the detection signal of the wheel speed sensor 50 and the steering angle of the steering wheel based on the detection signal of the steering angle sensor 58. It is judged. If it is determined in S5 that the roll state is set, that is, if it is determined that the rolling control mode should be controlled, the control mode is determined to be anti-roll control.

  When it is determined in S5 that the rolling control should not be performed, it is determined to perform the bouncing control mode control, and in subsequent S6, it is determined whether or not the sensitive control should be performed. Specifically, the degree of road surface roughness is estimated based on the vertical acceleration of the G sensor built in the height control sensor 52, and the determination is made based on the estimation result. If it is determined in S6 that the sensitive control should be performed, the control mode is determined to be the sensitive control. If it is determined that the sensitive control should not be performed, there is a control mode and control is determined. The five control modes are determined by the control mode determination process of S3 to S6, and one of the five individual mode controls a to e of S7 to S11 is executed according to the determination result.

  The individual mode control process of S7 to S11 is executed by either the individual mode control a routine or the individual mode control e routine. Since these routines are similar, the individual mode control routine shown in the flowchart in FIG. 6 is illustrated as a virtual one routine in which they are summarized. The individual mode control routines a to e will be described together.

In the control in the individual mode, first, in S31, for each of the four actuators 36, a control target value, which is a target value when the vehicle body mass state is the standard state, is determined. In each of the five individual modes, the standard target value is determined based on, for example, the detection value of the G sensor included in the height control sensor 52 according to a different theory, process, or the like. Regarding the determination of the standard target value, various known theories, processes and the like can be widely adopted, and the description thereof is omitted here. Further, as described above, in this embodiment, the damping coefficient that is the characteristic value of each suspension cylinder 32 is adopted as the control target value. In S31, the target in the standard state is set for each actuator 36. A standard target attenuation coefficient C ₀ ^*, which is an attenuation coefficient, is determined.

In subsequent S32, a correction value that is employed in correcting the standard target attenuation coefficient C ₀ ^* is selected. The correction value corresponding to the control mode is selected from the three correction values stored in the RAM. Again, the bouncing correction value for tilt control and sway sensitive control, the pitching correction value for anti-dive control and anti-squat control, and the rolling correction value for anti-roll control, respectively, are attenuation coefficient corrections. Selected as value D.

In the next S33, a target damping coefficient C ₁ ^*, which is a control target value that is actually used, is determined. Specifically, the previously determined standard target damping coefficient C ₀ ^* is corrected. Specifically, one selected damping coefficient correction value is selected for each of the standard target damping coefficients C ₀ ^* of the four actuators 36. Multiply by D to determine the target damping coefficient C ₁ ^* . In the next S34, the four actuators 36 are controlled based on the target damping coefficient C ₁ ^* . More specifically, the operation position of each actuator 36 is determined in a stepwise manner according to the value of the target damping coefficient C ₁ ^* , and it is determined at which step the actuator 36 is operated. An operation command is issued to the actuator 36 so as to reach the determined operation position.

  The series of processes described above is finished, and the execution of one damping force adjustment control program is finished. As described above, the damping force adjustment control program is continuously repeated at short time intervals until the ignition switch is turned off. In the damping force adjustment control performed by executing the above program, in addition to the damping force being appropriately adjusted according to the vehicle body mass state, the control target value for each of the four actuators 36 is determined by one common correction value. Since it is corrected, the control is simple.

<Functional configuration of vehicle suspension control device>
If the suspension ECU 70, which is a suspension control device that executes the damping force adjustment control, is expressed centering on the function thereof, a functional block diagram shown in FIG. 7 is obtained. The functional configuration of the ECU 70 will be described below with reference to this figure.

  The ECU 70 includes a vehicle body mass state related information acquisition unit 80, a correction value determination unit 82, a control mode determination unit 84, a plurality of individual mode control units 86, and a data / program storage unit 88. The correction value determination unit 82 includes three determination units: a bouncing correction value determination unit 90, a pitching correction value determination unit 92, and a rolling correction value determination unit 94, and each individual mode control unit 86 includes a standard target value. A determination unit 96 and an actuator control unit 98 are provided. Further, the data / program storage unit 88 includes a known data storage unit 100.

The vehicle body information related information acquisition unit 80 is a functional unit that acquires vehicle body mass state related information, which is information that directly or indirectly indicates the vehicle body mass state, based on information of various sensors provided in the vehicle. Corresponds to a part for executing the processes of S23. The correction value determination unit 82 is a functional unit that determines a correction value for correcting the standard target value determined by the standard target value determination unit 96, and corresponds to a part that executes the processes of S24 to S26. Specifically, the part that executes the process of S24 is the bouncing correction value determining unit 90, the part that executes the process of S25 is the pitching correction value determining unit 92, and the part that executes the process of S26 is the rolling correction value determining unit 94. Has been. The control mode determination unit 84 estimates the vehicle running state based on information from various sensors and the like, and based on the estimation, determines the individual control mode to be actually performed from the following five control modes. And corresponds to a part for executing the processes of S3 to S6. Five individual mode control units 86 are provided corresponding to each of a) tilt control, b) sway sensitive control, c) anti-dive control, d) anti-squat control, and e) anti-roll control. The standard target value determination unit 96 included in each individual mode control unit 86 is a functional unit that determines the standard target value of each actuator corresponding to each of the four wheels according to the control mode, and executes the above-described S31. It corresponds to the part. The actuator control unit 98 also uses a control target value used for actual control of each actuator 36 based on the standard target value determined by the standard target value determination unit 96 and the correction value determined by the correction value determination unit 82. Is a functional unit that controls each of the actuators 36 based on the control target value, and corresponds to a part that executes the above-described S32 to S34. The data program storage unit 88 is a functional unit that stores the damping force adjustment control program and various data used for the damping force adjustment control, and includes a part of a ROM of a computer included in the ECU 70. Yes. In particular, the known data storage unit 100 is a part for storing the known data such as the vehicle body mass M ₀ in the standard state used when determining the correction value.

It is a conceptual diagram which shows the vibration model of the vehicle body on which the suspension control apparatus for vehicles which is an Example of this invention relies when performing damping force adjustment control according to a vehicle body mass state. 1 is a perspective view showing a hardware configuration of an entire vehicle suspension system controlled by a suspension control device of an embodiment. The block diagram about the part deeply related to damping force adjustment control among the hardware constitutions shown in FIG. 2 is shown. It is a flowchart which shows the damping force adjustment control program performed by the suspension control apparatus of a present Example. It is a flowchart which shows the correction value determination routine which comprises a part of damping force adjustment control program shown in FIG. It is a slow chart which shows the individual control routine which comprises a part of damping force adjustment control program shown in FIG. It is a functional block diagram which shows typically the function of the suspension control apparatus of a present Example.

Explanation of symbols

32: Suspension cylinder 34: Air suspension device 36: Damping force change actuator 54: Gas pressure sensor 70: Suspension electronic control unit (vehicle suspension control device) 80: Vehicle body mass state acquisition unit 82: Correction value determination unit 84: Control mode Determination unit 86: Individual mode control unit 88: Data program storage unit 90: Bouncing correction value determination unit 92: Pitching correction value determination unit 94: Rolling correction value determination unit 96: Standard target value determination unit 98: Actuator control unit 100: Known data storage

Claims (8)

A control device for controlling each of the damping force changing actuators provided in each of the suspension devices in order to change the damping force of each of the suspension devices provided for each of the wheels,
A standard target value determining unit that determines a standard target value that is a control target value of each of the damping force changing actuators when the vehicle body mass state is a standard state;
A vehicle body mass state related information acquisition unit for acquiring vehicle body mass state related information, which is information indicating the vehicle body mass state directly or indirectly;
Based on the vehicle body mass state related information acquired by the vehicle body mass state related information acquisition unit, each of the standard target values for correcting the standard target value so that the attenuation ratio of the vehicle body rigid body vibration becomes substantially constant regardless of the vehicle body mass state. A correction value determining unit for determining a correction value common to the suspension device;
Each control target value of the damping force changing actuator is determined based on the standard target value determined by the standard target value determination unit and the correction value determined by the correction value determination unit, and based on the control target value A suspension control device for a vehicle, comprising: an actuator control unit that controls each of the damping force changing actuators.   The correction value determination unit calculates the correction value based on the vehicle body mass state related information acquired by the vehicle body mass state related information acquisition unit using a function based on a vibration model in which the vehicle body is regarded as one rigid body. The vehicle suspension control apparatus according to claim 1, wherein   The bouncing correction value, which is the correction value used in the control for bouncing of the vehicle body, is set so that the bouncing attenuation ratio as the attenuation ratio of the vehicle body rigid body vibration is substantially constant regardless of the vehicle body mass state. The vehicle suspension apparatus according to claim 1, further comprising a bouncing correction value determining unit that determines the bouncing correction value.   The bouncing correction value determination unit determines the bouncing correction value as a ratio value of a bouncing damping coefficient that is a damping coefficient of a rigid body vibration, and the bouncing damping coefficient and the body mass state in an actual body mass state are in a standard state. 4. The vehicle suspension control device according to claim 3, wherein the vehicle suspension control device is determined to be a value of a ratio to a bouncing damping coefficient in the case of.   The correction value determining unit sets the pitching correction value, which is the correction value used in the control for the pitching of the vehicle body, so that the pitching attenuation ratio as the attenuation ratio of the vehicle body rigid body vibration is substantially constant regardless of the vehicle body mass state. The vehicle suspension control device according to any one of claims 1 to 4, further comprising a pitching correction value determination unit for determining.   The pitching correction value determination unit determines the pitching correction value as a ratio value of a pitching damping coefficient that is a damping coefficient of a rigid body vibration, and the pitching damping coefficient and the body mass state in an actual body mass state are in a standard state. 6. The vehicle suspension control device according to claim 5, wherein the vehicle suspension control device is determined to be a value of a ratio to a pitching damping coefficient in the case of.   The correction value determining unit sets the rolling correction value, which is the correction value used in the control of rolling of the vehicle body, so that the rolling damping ratio as the damping ratio of the vehicle body rigid body vibration is substantially constant regardless of the vehicle body mass state. The vehicle suspension control device according to any one of claims 1 to 6, further comprising a rolling correction value determination unit for determining. The rolling correction value determining unit determines the rolling correction value as a ratio of a rolling damping coefficient that is a damping coefficient of a rigid body vibration, and the rolling damping coefficient and the body mass state in an actual body mass state are in a standard state. The vehicle suspension control device according to claim 7, wherein the vehicle suspension control device is determined to be a ratio value with a rolling damping coefficient in the case of

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