JP2009073415A - Vehicle attitude control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a posture control device for a vehicle capable of controlling the behavior of the posture change when turning the vehicle in consideration of the posture change accompanying the vehicle height adjustment.
A suspension ECU 21 inputs stroke amounts hfl, hfr, hrf, hrr of each shock absorber in step S12, and determines a reference stroke amount “0” in step S13. If the vehicle height is adjusted in step S14, the reference pitch angle θb corresponding to the reference stroke amount is determined in step S15, and the difference angle between the pitch angle θb and the actual pitch angle θ is determined as the offset amount J. To do. The ECU 21 determines the target pitch angle θah by correcting the target pitch angle θa for controlling the behavior of the roll using the offset amount J by executing the roll control routine in step S16. Thereby, even if vehicle height adjustment is made at the time of vehicle turning, the behavior of a roll can be controlled appropriately.
[Selection] Figure 3

Description

  The present invention relates to a vehicle height adjustment function of a shock absorber that is disposed between a vehicle body and wheels and has a function of adjusting the vehicle height, and a vehicle attitude control device that controls the attitude of the vehicle body by controlling a damping force.

  2. Description of the Related Art Conventionally, a vehicle height adjustment function of a shock absorber disposed between a vehicle body and a wheel and a posture control device that controls the posture of the vehicle by controlling the damping force of the shock absorber have been actively proposed. For example, Patent Document 1 below discloses a suspension characteristic calculation method that provides a design index of a suspension in consideration of the correlation between roll and pitch generated in a vehicle body. In this suspension characteristic calculation method, the pitch moment due to the suspension geometry is calculated as the sum of the vertical force on the front and rear wheels by the product of the geometric proportionality coefficient on the front and rear wheels and the square of the tire lateral force, The pitch moment due to the damping force of the suspension is calculated from the product of the damping force proportional coefficient and the roll rate. Then, the pitch angle is calculated from the product of the sum of the two calculated pitch moments, the gain of the pitch angle with respect to the pitch moment, and the phase lag of the pitch angle, and based on the calculated pitch angle, the pitch angle and the roll angle are calculated. The phase difference is calculated.

  When a suspension is designed according to such a suspension characteristic calculation method, for example, an expansion difference or a compression difference between a shock absorber disposed on the front wheel side and a shock absorber disposed on the rear wheel side is appropriately set. By setting, roll and pitch generation timing can be synchronized. As a result, steering stability can be improved.

  Further, for example, Patent Document 2 below discloses a vehicle height adjustment device that accurately determines a turning acceleration / deceleration traveling state and prevents unnecessary and inappropriate vehicle height adjustment. The conventional vehicle height adjusting device calculates a turning state amount of the vehicle and calculates an acceleration / deceleration state amount based on the calculated turning state amount. The vehicle height adjustment is prohibited when the sum of the calculated turning state amount and acceleration / deceleration state amount exceeds a predetermined value. As a result, unnecessary or inappropriate vehicle height adjustment with respect to a vehicle height change that occurs when the vehicle turns can be prevented.

Further, in Patent Document 3 below, the amount of signal fed back to the control unit is continuously adjusted according to the relative vertical displacement amount of each axle and the vehicle body, and the operation range of the hydraulic suspension mechanism is limited. An attitude control device is shown. This conventional vehicle body posture control device obtains the roll amount, pitch amount, and vertical displacement amount of the vehicle body from the amount of change in vehicle height of each wheel, and the feedback gain when obtaining the roll control torque, pitch control torque, and vertical displacement control force. To be adjusted. In addition, the roll control torque during turning and the pitch control torque during acceleration / deceleration are obtained from the roll amount, pitch amount, lateral acceleration, and longitudinal acceleration, and the oil amount of the hydraulic suspension mechanism of the wheel is adjusted. ing. As a result, the mechanical collision of the operating portion in the hydraulic suspension mechanism can be avoided and the ride comfort can be improved with respect to an excessive vehicle height change amount.
JP 2007-8373 A Japanese Utility Model Publication No. 2-19604 JP-A-5-305806

By the way, in general, in order to ensure the steering stability when turning the vehicle, it is preferable to synchronize the generation timing of the roll and the pitch, as shown in Patent Document 1 described above, and It is said that it is preferable to have a pitch angle that is slightly forward inclined.
However, in order to ensure steering stability when the vehicle is turning, for example, when the behavior of the roll generated on the vehicle body is controlled by appropriately changing the damping force of the shock absorber, the vehicle height adjustment is performed. There is a possibility that the posture to be targeted changes with the vehicle height adjustment and proper roll behavior control cannot be performed. On the other hand, for example, when a change in vehicle height when an occupant gets on or a change in vehicle height when a heavy object is loaded, it is desirable that the vehicle can quickly return to the target vehicle height.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to control the attitude of a vehicle capable of controlling the behavior of the attitude change when the vehicle is turning in consideration of the attitude change accompanying the vehicle height adjustment. To provide an apparatus.

  In order to achieve the above object, the present invention is characterized in that the posture of the vehicle body is controlled by controlling the vehicle height adjustment function and the damping force of a shock absorber disposed between the vehicle body and the wheel and having a function of adjusting the vehicle height. In the vehicle attitude control apparatus for controlling the vehicle, the actual roll generated in the vehicle body based on the correlation between the roll angle and the pitch angle set in advance to control the roll generated in the vehicle body as the vehicle turns. Target pitch angle determining means for determining a target pitch angle corresponding to the angle, and when the vehicle height is adjusted by the vehicle height adjusting function, the target pitch angle determined by the target pitch angle determining means is Target pitch angle correction means for correcting using a high change amount, and change control of the damping force of the shock absorber to realize the target pitch angle corrected by the target pitch angle correction means In that a damping force control means that.

  In this case, the shock absorber includes, for example, an electric actuator that is electrically operated and controlled to change the damping force of the shock absorber, and the damping force control means electrically operates the electric actuator. By controlling, it is preferable to change and control the damping force of the shock absorber.

  Further, in this case, the target pitch angle correction means includes, for example, the stroke amount detection means for detecting the stroke amount of the shock absorber, and the stroke amount detected by the stroke amount detection means when the vehicle starts turning. Reference stroke amount determining means for determining as a reference stroke amount, reference pitch angle determining means for determining an actual pitch angle of a vehicle body corresponding to the reference stroke amount determined by the reference stroke amount determining means as a reference pitch angle, and the vehicle In order to correct the target pitch angle determined by the target pitch angle determining means, the difference between the actual pitch angle that changes with the adjustment of the vehicle by the adjusting function and the reference pitch angle determined by the reference pitch angle determining means And offset amount determination means to determine as the offset amount .

  According to these, the change in posture that occurs as the vehicle turns, that is, the target pitch angle for controlling the behavior of the roll is determined, and the amount of change in the vehicle height that changes with the vehicle height adjustment is used. The target pitch angle can be corrected. More specifically, the stroke amount of the shock absorber when the vehicle starts turning can be determined as the reference stroke amount, and the actual pitch angle corresponding to the reference stroke amount can be determined as the reference pitch angle. Then, the change amount of the actual pitch angle that changes with the vehicle height adjustment from the reference pitch angle, that is, the difference can be determined as the offset amount for correcting the target pitch angle.

  Thus, by determining the offset amount, the target pitch angle can be corrected synchronously in accordance with the actual pitch angle accompanying the vehicle height change by the vehicle height adjustment. In other words, the target pitch angle can be corrected appropriately according to the vehicle height change accompanying the vehicle height adjustment, so that the vehicle height can be adjusted even when the vehicle is turning, The behavior of the roll generated along with this can also be controlled appropriately. Thus, by correcting the target pitch angle, it is possible to accurately determine the damping force of the shock absorber necessary for controlling the behavior of the roll, and for example, electrically control it. As a result, good steering stability can be ensured.

  Further, in this case, the damping force control means realizes the target pitch angle corrected by the physical quantity detection means for detecting a predetermined physical quantity that changes as the vehicle turns and the target pitch angle correction means. A total damping force calculating means for calculating a total damping force to be generated in cooperation between the left and right shock absorbers disposed on the front wheel side of the vehicle and the left and right shock absorbers disposed on the rear wheel side of the vehicle; A shock absorber disposed inside the swing and a shock absorber disposed outside the swing in accordance with a predetermined physical quantity detected by the physical quantity detection means based on the total damping force calculated by the total damping force calculation means. The damping force of the shock absorber disposed inside the turning is larger than the damping force of the shock absorber arranged outside the turning. A total damping force distribution means for distributing the shock absorber, and the damping force of the shock absorber disposed inside the swing and the damping force of the shock absorber disposed outside the swing distributed by the total damping force distribution means. Based on this, the damping force of each shock absorber may be changed and controlled. Here, the predetermined physical quantity detected by the physical quantity detection means includes, for example, lateral acceleration generated when the vehicle turns, yaw rate generated when the vehicle turns, and the steering wheel operation amount operated by the driver. It should be at least one of them.

  In this case, the total damping force calculating means calculates, for example, the actual pitch angle generated in the vehicle body, and the difference between the calculated actual pitch angle and the target pitch angle corrected by the target pitch angle correcting means. It is preferable to calculate the value and calculate the total damping force at which the calculated difference value is substantially “0”.

  According to these, the damping force control means can calculate the total damping force that should be generated in cooperation by the shock absorbers arranged in the front, rear, left, and right directions in order to realize the corrected target pitch angle. . Then, the damping force control means converts the total damping force to the outside of the turning by the shock absorber disposed on the inside of the turn according to a predetermined physical quantity (lateral acceleration, yaw rate, operation amount of the steering handle, etc.). It can distribute so that it may become larger than the damping force of the shock absorber arrange | positioned.

  Thus, in a vehicle turning in the same direction, the direction of action of a predetermined physical quantity, specifically, the direction of occurrence of lateral acceleration or yaw rate and the direction of operation of the steering wheel are always the same throughout the turning state. The behavior of the roll can always be controlled using the shock absorber inside the turning as a fulcrum. Accordingly, the generation behavior of the roll generated in the vehicle body in the turning state can be made the same, in other words, the phase between the roll angle and the pitch angle can be made substantially the same, and the behavior of the posture change when the vehicle turns Can be constant. In this way, by making the behavior of the posture change when turning the vehicle constant, the behavior of the roll can be controlled appropriately (more naturally), and the driving stability of the vehicle can be greatly improved. Can do.

  Further, the total damping force distribution unit is configured to change the total damping force calculated by the total damping force calculation unit in proportion to the predetermined physical quantity detected by the physical quantity detection unit, The absorber may be distributed so that the damping force of the absorber is larger than the damping force of the shock absorber disposed outside the turning.

  In this case, more specifically, the total damping force distributing means is configured to apply the total damping force calculated by the total damping force calculating means to a shock absorber disposed inside the turning and a shock arranged outside the turning. While distributing equally to the absorber, a damping force distribution amount proportional to the predetermined physical quantity detected by the physical quantity detection means is added to the shock absorber disposed inside the turning, while on the outside of the turning It is preferable to subtract from the shock absorber disposed and distribute the shock absorber so that the damping force of the shock absorber disposed inside the swing is larger than the damping force of the shock absorber disposed outside the swing.

  According to these, the total damping force required to realize the corrected target pitch angle is proportional to the magnitude of the predetermined physical quantity, and the damping force of the shock absorber disposed inside the turning and the outside of the turning. It can be distributed to the damping force of the installed shock absorber. At this time, a distribution amount proportional to the size of a predetermined physical quantity is calculated, and the calculated distribution amount is added to a shock absorber disposed inside the swing where the total damping force is evenly distributed. By subtracting from the shock absorber arranged outside, the damping force of the shock absorber arranged inside the turning can be made larger than the damping force of the shock absorber arranged outside the turning.

  Thereby, it is possible to determine the damping force to be generated by the shock absorber disposed inside the turning and the shock absorber arranged outside the turning very strictly. In addition, by adding or subtracting the distribution amount proportional to the predetermined physical quantity, for example, the left and right absorbers arranged on the front wheel side to control the roll behavior generate the total damping force required, while turning inside. It is possible to maintain a state in which the damping force of the disposed shock absorber is greater than the damping force of the shock absorber disposed on the outer side of the turn. Therefore, by making the behavior of the posture change when turning the vehicle constant, the behavior of the roll can be controlled more accurately, and the steering stability of the vehicle can be greatly improved.

  Further, the damping forces of the left and right shock absorbers arranged on the front wheel side and the rear wheel side are each switched in stages by a plurality of switching stages having a predetermined change width, and the total damping force distribution The means determines the total damping force calculated by the total damping force calculating means based on the predetermined physical quantity detected by the physical quantity detecting means, so that the damping force of the shock absorber disposed inside the turning is outside the turning The number of switching stages of the shock absorber disposed inside the turning and the shock absorber arranged outside the turning may be determined and distributed so as to be larger than the damping force of the shock absorber disposed on the inside.

  In this case, the predetermined change width of the damping force between the number of switching stages determined for the shock absorber disposed inside the turning is, for example, a change in the predetermined physical quantity detected by the physical quantity detecting means. The predetermined change amount of the damping force between the switching stages determined with respect to the shock absorber disposed outside the turning has a large value with respect to the predetermined physical quantity detected by the physical quantity detecting means It is good to have a small value for the change of. Further, the number of switching stages may be determined by changing linearly or proportionally with respect to a change in the predetermined physical quantity detected by the physical quantity detecting means.

  According to these, by determining the number of switching stages of the shock absorber according to a predetermined physical quantity, the damping force of the shock absorber disposed on the inner side of the swing is more than the damping force on the shock absorber disposed on the outer side of the swing. Can be bigger. This simplifies the logic for distributing the total damping force to the shock absorbers arranged inside and outside the turning, for example, calculating the total damping force distributing means formed from a microcomputer or the like. The load can be greatly reduced. As a result, for example, the heat generation of the total damping force distribution means accompanying the calculation can be greatly suppressed, and it is not necessary to provide a cooling means or the like, and the size can be reduced.

  Hereinafter, a vehicle attitude control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a vehicle attitude control device 10 according to an embodiment of the present invention. The vehicle attitude control device 10 includes shock absorbers 11, 12, 13, and 14 that connect the vehicle body and the wheels of the vehicle, that is, the left and right front and rear wheels, respectively.

  Each of the shock absorbers 11, 12, 13, and 14 includes, for example, rotary valves 11a, 12a, 13a, and 14a as electric actuators that continuously change the flow diameter of a working fluid (oil, high-pressure gas, etc.). . In addition, although detailed description is abbreviate | omitted, each rotary valve 11a, 12a, 13a, 14a is provided with the electric drive means (For example, an electric motor, a solenoid, etc.) which is not shown in figure. And each rotary valve 11a, 12a, 13a, 14a changes the flow path diameter of a working fluid by being electrically controlled, As a result, there is no damping force characteristic of each shock absorber 11, 12, 13, 14 It has been changed to the stage.

  The shock absorbers 11, 12, 13, and 14 are provided with air chambers 11b, 12b, 13b, and 14b for adjusting the vehicle height. The volume of the air chambers 11b, 12b, 13b, and 14b changes when the compressed air is supplied and discharged by the compressed air supply / discharge device 15 including a valve and a compressor whose operation is electrically controlled. Change and adjust. The structure of the air chambers 11b, 12b, 13b, and 14b and the structure of the compressed air supply / discharge device 15 that supplies and discharges compressed air are not directly related to the present invention, and a well-known structure can be adopted. Therefore, the detailed description is abbreviate | omitted.

  In the present embodiment, the shock absorbers 11, 12, 13, and 14 are provided with air chambers 11b, 12b, 13b, and 14b for adjusting the vehicle height with compressed air. However, as a mechanism for adjusting the vehicle height, for example, a hydraulic vehicle height adjusting mechanism that adjusts the vehicle height by supplying and discharging hydraulic pressure can be employed.

  Next, the electric control device 20 that controls the attitude of the vehicle will be described. As shown in FIG. 2, the electric control device 20 changes the damping force of the shock absorbers 11, 12, 13, and 14, thereby controlling a change in posture during turning of the vehicle. ECU 21) and a height control electronic control unit 22 (hereinafter simply referred to as height control ECU 22) that adjusts the vehicle height by operating the compressed air supply / discharge device 15. Here, the suspension ECU 21 and the height control ECU 22 are connected to each other via the communication line A.

  The suspension ECU 21 is a microcomputer whose main components are a CPU, a ROM, a RAM, and the like. The suspension ECU 21 controls the damping force of the shock absorbers 11, 12, 13, and 14 by executing various programs including an attitude control program to be described later. The height control ECU 22 is also a microcomputer whose main components are a CPU, a ROM, a RAM, and the like. The height control ECU 22 controls the operation of the compressed air supply / exhaust device 15 by executing various programs, and adjusts the vehicle height by supplying and discharging compressed air to and from the air chambers 11b, 12b, 13b, 14b. is there.

  On the input side of the suspension ECU 21, a lateral acceleration sensor 23 as a physical quantity detecting means for detecting a lateral acceleration as a predetermined physical quantity generated in the vehicle, and shock absorbers 11, 12, 13, 14 corresponding to the vehicle height are provided. Stroke sensors 24, 25, 26, and 27 for detecting each stroke amount are connected. Further, stroke sensors 24, 25, 26, and 27 are connected to the input side of the height control ECU 22.

  The lateral acceleration sensor 23 detects a lateral acceleration G generated in the vehicle, and outputs the detected lateral acceleration G to the suspension ECU 21. Here, the lateral acceleration sensor 23 outputs, as a positive value, the lateral acceleration G generated when the vehicle turns leftward from the straight traveling state (hereinafter simply referred to as left turning), and turns rightward from the straight traveling state ( Hereinafter, the lateral acceleration G generated when the vehicle is simply turned to the right is output as a negative value.

  As shown in FIG. 1, the stroke sensors 24, 25, 26, and 27 are assembled to the shock absorbers 11, 12, 13, and 14. As shown in FIG. 2, the stroke sensors 24, 25, 26, and 27 detect the stroke amounts hfl, hfr, hrl, and hrr of the shock absorbers 11, 12, 13, and 14, respectively. The amounts hfl, hfr, hrl, hrr are output to the suspension ECU 21 and the height control ECU 22.

  Further, driving circuits 28a, 28b, 28c, 28d for controlling the operation of the rotary valves 11a, 12a, 13a, 14a are connected to the output side of the suspension ECU 21. A drive circuit 29 for controlling the operation of the compressed air supply / discharge device 15 is connected to the output side of the height control ECU 22. With this configuration, the suspension ECU 21 can control the damping force characteristics of the shock absorbers 11, 12, 13, and 14, and the height control ECU 22 can adjust and control the vehicle height.

  Next, the operation of the vehicle attitude control device 10 configured as described above will be described in detail.

  The vehicle attitude control device 10 stabilizes the behavior of the roll generated when the vehicle is in a turning state, in other words, the damping force of the shock absorbers 11, 12, 13, and 14 in order to improve steering stability. Change control. That is, the suspension ECU 21 more specifically corrects the actual pitch angle θ, which will be described later, so that a predetermined correlation is established between the actual roll angle φ generated in the vehicle body and the actual pitch angle θ. In order to change until the pitch angle θah is reached, the damping force of the shock absorbers 11, 12, 13, and 14 is changed and controlled.

  In addition, the vehicle attitude control device 10 may set the vehicle height to a preset value when the vehicle height changes, for example, when a heavy object is loaded on a trunk provided in the vehicle or when an occupant gets on the vehicle. To control the posture. That is, the height control ECU 22 executes a predetermined program (not shown) to operate the compressed air supply / discharge device 15 via the drive circuit 29, thereby supplying compressed air to the air chambers 11b, 12b, 13b, 14b. Supply and discharge. At this time, the height control ECU 22 inputs the stroke amounts hfl, hfr, hrl, and hrr of the shock absorbers 11, 12, 13, and 14 from the stroke sensors 24, 25, 26, and 27, and sets the preset target vehicle height. The compressed air supply / discharge device 15 is operated until When the vehicle height is changed to the target vehicle height, the vehicle height is changed at a preset vehicle height adjustment speed.

  By the way, when the suspension ECU 21 and the height control ECU 22 independently change the actual pitch angle θ until it becomes a target pitch angle θa (to be described later) or adjust the vehicle height, The reference point for the ECU 21 to change the actual pitch angle θ may change. For this reason, the suspension ECU 21 cannot appropriately change the actual pitch angle θ to the target pitch angle θa, and as a result, there is a possibility that the improvement in steering stability cannot be achieved. This will be specifically described below.

  For example, when considering a case where a heavy object is loaded on the trunk of the vehicle, the shock absorbers 13 and 14 provided on the rear wheel side are compressed, and the vehicle body is in a state where the rear part is sunk, that is, a so-called backward tilted state. For this reason, the height control ECU 22 operates the compressed air supply / discharge device 15 according to the stroke amount of the shock absorbers 13 and 14 in the compression direction, and compresses them into the air chambers 13b and 14b provided in the shock absorbers 13 and 14. Supply air. As a result, the rear part of the vehicle body begins to rise at a predetermined vehicle height adjustment speed. Then, the height control ECU 22 slightly leans forward from the horizontal as the preset vehicle height based on the stroke amounts hfl, hfr, hrl, hrr input from the stroke sensors 24, 25, 26, 27. Until the compressed air supply / discharge device 15 is operated.

  On the other hand, as described above, when the vehicle starts to travel while the vehicle height is being adjusted, and when the vehicle further starts to turn, the suspension ECU 21 controls the behavior of the roll that is generated as the vehicle turns. Therefore, the damping force of the shock absorbers 11, 12, 13, and 14 is changed and controlled. That is, the suspension ECU 21 changes and controls the damping force so that the actual pitch angle θ becomes the target pitch angle θa. At this time, since the height control ECU 22 independently adjusts the vehicle height on the rear wheel side, when the suspension ECU 21 changes the damping force, the actual pitch θ becomes larger than the target pitch θa. Will become a larger forward leaning posture. In general, it is said that the forward leaning posture is preferable as the posture of the vehicle body when turning the vehicle, but it is not preferable that the forward leaning posture becomes too large.

  For this reason, the suspension ECU 21 repeatedly executes the attitude control program shown in FIG. 3 at a predetermined short time interval in order to stabilize the roll behavior in consideration of the vehicle height changed by the vehicle height adjustment by the height control ECU 22. To do. Hereinafter, this attitude control program will be described in detail.

  The execution of the attitude control program is started in step S10 after execution of the predetermined initialization program. Then, the suspension ECU 21 determines in step S11 whether or not the vehicle is turning. That is, for example, the suspension ECU 21 inputs the lateral acceleration G detected by the lateral acceleration sensor 23, and determines whether or not the vehicle is turning based on the value of the input lateral acceleration G.

  Then, if the vehicle is in a turning state, the suspension ECU 21 determines “Yes” and executes each step process after step S12. On the other hand, if the vehicle is not in a turning state, in other words, if the vehicle is in a straight traveling state, the suspension ECU 21 determines “No”, proceeds to step S18, and temporarily ends the execution of the attitude control program. Then, after a predetermined short period of time, the suspension ECU 21 again starts executing the attitude control program in step S10.

  In step S12, the suspension ECU 21 inputs the stroke amounts hfl, hfr, hrl, hrr of the shock absorbers 11, 12, 13, 14 detected by the stroke sensors 24, 25, 26, 27 at the start of turning. When the suspension ECU 21 inputs the stroke amounts hfl, hfr, hrl, and hrr, the process proceeds to step S13.

  In step S13, the suspension ECU 21 sets the stroke amounts hfl, hfr, hrl, and hrr input in step S12 to “0” as the reference stroke amount, that is, the stroke reference point. That is, the suspension ECU 21 sets the stroke amounts hfl, hfr, hrl, hrr of the shock absorbers 11, 12, 13, 14 at the time when the turning of the vehicle is started as stroke reference points in the current posture control. Accordingly, the stroke sensors 24, 25, 26, and 27 detect the stroke amounts hfl, hfr, hrl, and hrr of the shock absorbers 11, 12, 13, and 14 based on the set stroke reference point in the current posture control. To do.

  Subsequently, the suspension ECU 21 determines in step S14 whether or not the height control ECU 22 is adjusting and controlling the vehicle height. That is, the suspension ECU 21 checks with the height control ECU 22 whether or not the vehicle height adjustment control is currently being executed via the communication line A. The height control ECU 22 outputs predetermined control information indicating the execution state of the vehicle height adjustment control to the suspension ECU 21. If the height control ECU 22 is currently executing vehicle height adjustment control based on the acquired control information, the suspension ECU 21 determines “Yes” and proceeds to step S15. On the other hand, if the height control ECU 22 is not executing the vehicle height adjustment control, it is determined as “No” and the process proceeds to step S16.

  In step S15, the suspension ECU 21 determines the offset amount J of the reference point (origin) of the target pitch angle θa calculated in step S16 described later. That is, the stroke amounts hfl, hfr, hrl, hrr of the shock absorbers 11, 12, 13, 14 changed by the vehicle height adjustment control by the height control ECU 22 from the stroke reference point set in step S13, in other words, the actual pitch angle θ. An offset amount J for changing a reference point (origin point) of a target pitch angle θa, which will be described later, is determined in accordance with the change of. Hereinafter, this will be specifically described with reference to FIG.

  4A schematically shows a vehicle height change state when the height control ECU 22 performs vehicle height adjustment control, and FIG. 4B shows a state in which the vehicle height is changed by the vehicle height adjustment control. A state in which the suspension ECU 21 changes the offset amount J is schematically shown. As shown in FIG. 4 (a), if the vehicle body is tilted backward before the vehicle starts to travel, the height control ECU 22 moves the vehicle until the vehicle body becomes substantially horizontal at a predetermined vehicle height adjustment speed. Raise the wheel side. In this case, for example, it is assumed that the vehicle height adjustment speed takes W seconds at Zmm / second in order to raise the vehicle body before the start of travel from the rear tilted state where the rear wheel side sinks by Yo ° to the substantially horizontal state.

  As described above, when the vehicle height is adjusted and the vehicle starts turning after y seconds, as shown in FIG. 4B, the rear wheel side is raised by an angle Y ° corresponding to y · Zmm. At this time, the vehicle body is in a tilted state after the rear wheel side sinks by (Yo−Y) °. Here, the suspension ECU 21 sets the stroke reference point to “0” by the process of step S13 when y seconds have elapsed since the vehicle started running and turned. Then, the suspension ECU 21 virtually sets the vehicle body inclination (Yo−Y) ° at this time point to a state where the actual pitch angle θ is “0” (hereinafter, the actual pitch angle where the virtual pitch angle is virtually “0” is referred to as “0”). Reference pitch angle θb).

  On the other hand, the height control ECU 22 continues to execute the vehicle adjustment control and brings the vehicle body into a substantially horizontal state in (W−y) seconds. That is, the height control ECU 22 adjusts the vehicle height at an ascending speed of (Yo−Y) / (W−y). For this reason, the actual pitch angle θ of the vehicle body also changes at a change rate of (Yo−Y) / (W−y) by the vehicle height adjustment control of the height control ECU 22.

  Therefore, the suspension ECU 21 determines the difference angle (θ−θb) between the actual pitch angle θ and the reference pitch angle θb, which is changed by the height adjustment control of the height control ECU 22, as the offset amount J. In this way, by determining the offset amount J, the offset amount J is more specifically expressed as (Yo−Y) / (W−y) in accordance with the vehicle height adjustment control of the height control ECU 22. It will change at a changing rate. When the offset amount J is thus determined, the suspension ECU 21 proceeds to step S16.

  In step S16, the suspension ECU 21 executes a roll control routine shown in FIG. 5 in order to control the behavior of the roll generated along with the turning. Hereinafter, this roll control routine will be described in detail.

  The execution of the roll control routine is started in step S100. In step S101, the suspension ECU 21 calculates the actual roll angle φ and the actual pitch angle θ generated in the vehicle body. Here, as for the calculation method of the actual roll angle φ and the actual pitch angle θ calculated by the suspension ECU 21, since a well-known calculation method can be adopted, a detailed description thereof will be omitted, but a simple description will be given by way of example. Keep it.

The actual roll angle φ can be generally expressed by the following equation 1 where ω is the basic frequency of the roll angle (for example, corresponding to the steering frequency of the steering wheel).
φ = A · sinωt… Formula 1
However, A in said Formula 1 represents a predetermined | prescribed proportionality constant, and (omega) represents the fundamental frequency of a roll angle.

Moreover, since the actual pitch angle θ is generally proportional to the square of the actual roll angle φ, it can be expressed by the following formula 2 using the actual roll angle φ calculated according to the formula 1.
θ = B · φ ² Equation 2
However, B in the formula 2 represents a predetermined proportionality constant.

  Then, when the suspension ECU 21 calculates the actual roll angle φ and the actual pitch angle θ according to the equations 1 and 2, the process proceeds to step S102. As for the actual roll angle φ and the actual pitch angle θ, for example, instead of performing the calculation process or the estimation calculation process as described above, for example, a roll angle sensor and an actual pitch for detecting the actual roll angle φ generated in the vehicle. It goes without saying that the actual roll angle φ and the actual pitch angle θ can be directly detected using a pitch angle sensor that detects the angle θ.

  In step S102, the suspension ECU 21 determines a target pitch angle θah using a target map representing a correlation between a roll angle and a pitch angle at which steering stability is good when the vehicle is turning. This will be specifically described below.

  In general, it is said that it is effective to synchronize the generation timing of the roll and the pitch generated in the vehicle body in the turning state in order to improve the steering stability when the vehicle turns. That is, in a turning state, in a vehicle having excellent steering stability, the roll and the pitch tend to be generated in the vehicle body at the same time, and in a vehicle having poor steering stability, the roll and pitch tend to be generated in the vehicle body with a time difference. is there. This can be said that a vehicle having excellent steering stability in a turning state has a smaller phase difference between the roll angle and the pitch angle generated in the vehicle body.

  That is, in a vehicle having excellent steering stability, the phase difference between the roll angle and the pitch angle tends to be small. For example, the pitch angle has a very small hysteresis with respect to the change in the roll angle. It can be said that it becomes a characteristic. On the other hand, in a vehicle with poor steering stability, the phase difference between the roll angle and the pitch angle tends to increase, so the pitch angle can be said to be a change characteristic having a large hysteresis with respect to the change in the roll angle. .

  Therefore, in order to improve the steering stability of the vehicle, it is desirable that the correlation between the roll angle and the pitch angle changes based on a change characteristic having extremely small hysteresis as shown in FIG. . By the way, in general, a vehicle in a turning state travels by generating a roll by sinking a spring (ie, a vehicle body) outside the turning. Therefore, it is effective to control the pitch angle in order to obtain good steering stability against the change in the roll angle.

  In this case, the suspension ECU 21 adopts the relationship shown in FIG. 6 as the target map, and the actual pitch angle θ is set to the target pitch angle θa in the target map with respect to the actual roll angle φ generated in the vehicle body in the turning state. If they can be matched, roll control for ensuring good steering stability can be performed.

Incidentally, as described above, in the situation where the height control ECU 22 is executing the vehicle height adjustment control, the actual pitch angle θ is also changed by the vehicle height adjustment control. For this reason, if the target pitch angle θa is simply determined based on the actual roll angle φ under the situation where the vehicle height adjustment control is performed, the influence of the change in the actual pitch angle θ due to the vehicle height adjustment control is not taken into account. A target pitch angle θa cannot be determined. Therefore, it is necessary to consider the offset amount J determined in step S15. Therefore, the suspension ECU 21 corrects the target pitch angle θa by changing the origin of the target map in accordance with the offset amount J that changes with the vehicle height adjustment, as shown by the broken line in FIG. The actual pitch angle θ matches the corrected target pitch angle θah. In this case, the target pitch angle θa may be corrected by the offset amount J in accordance with the following equation 3, and the corrected target pitch angle θah may be calculated.
θah = θa + J… Formula 3

  Therefore, the suspension ECU 21, for example, on the coordinates of the target map whose origin has moved in accordance with the offset amount J, as shown in FIG. 7, the difference value between the target pitch angle θah and the actual pitch angle θ with respect to the actual roll angle φ. Δθ is calculated. Then, after calculating the difference value Δθ, the suspension ECU 21 proceeds to step S103.

  In step S103, the suspension ECU 21 sets the difference value Δθ to “0”, that is, the left and right shock absorbers 11 and 12 on the front wheel side and the rear wheel side necessary to make the actual pitch angle θ coincide with the target pitch angle θah. The total required damping force F for the left and right shock absorbers 13 and 14 is calculated. Hereinafter, the calculation of the total required damping force F will be described, but since various known methods can be adopted for this calculation, a detailed description will be omitted and a simple description will be given by way of example.

  The pitch angle generated in the vehicle body is generated by the pitch moment M in the longitudinal direction of the vehicle body. Therefore, the total required damping force F necessary for controlling the pitch angle generated in the vehicle body can be calculated using the pitch moment M.

That is, the pitch moment M can be calculated by the following equation 4.
M = I · (Δθ) '' + C · (Δθ) '+ K · (Δθ)
However, I in the said Formula 4 represents a moment of inertia, C represents a damping coefficient, and K represents a spring constant. Further, (Δθ) ″ in Equation 3 represents a second-order differential value of the difference value Δθ calculated in Step S102, and (Δθ) ′ represents a differential value of the difference value Δθ.

The total required damping force F can be calculated by dividing the vehicle body longitudinal pitch moment M expressed by Equation 4 by the vehicle wheel base L. That is, the total required damping force F can be calculated according to the following formula 5.
F = M / L ... Formula 5
When the total required damping force F is thus calculated, the suspension ECU 21 proceeds to step S104.

  In step S104, the suspension ECU 21 distributes the total required damping force F calculated in step S103 between the left and right shock absorbers 11 and 12 on the front wheel side and between the left and right shock absorbers 13 and 14 on the rear wheel side. Perform the operation. In the following description, since the same calculation can be performed on the front wheel side and the rear wheel side, the left and right shock absorbers 11 and 12 on the front wheel side will be representatively described.

  In distributing the total required damping force F to the left and right shock absorbers 11 and 12, the suspension ECU 21 uses a distribution amount X proportional to the magnitude of the lateral acceleration G generated in the vehicle in the turning state. More specifically, assuming that the total damping force F is required for the front wheel side of the vehicle, first, the total required damping force F is evenly distributed to the shock absorbers 11 and 12. .

  Then, the suspension ECU 21 adds the distribution amount X to the required damping force (F / 2) evenly distributed to the shock absorbers 11 and 12. At this time, the suspension ECU 21 positively distributes the required damping force (F / 2) of the shock absorber 11 (shock absorber 12) inside the turn based on the direction of the lateral acceleration G input from the lateral acceleration sensor 23. Add X. On the other hand, the suspension ECU 21 adds the negative distribution amount X to the required damping force (F / 2) of the shock absorber 12 (shock absorber 11) outside the turning.

That is, the damping force Fi required for the shock absorber 11 (shock absorber 12) corresponding to the inside of the turn and the damping force Fo required for the shock absorber 12 (shock absorber 11) corresponding to the outside of the turn are expressed by the following equations 6 and 7. Indicated by
Fi = (F / 2) + X ... Formula 6
Fo = (F / 2) -X ... Formula 7
Here, as described above, since the distribution amount X is proportional to the magnitude of the lateral acceleration G, it can be expressed by the following Expression 8.
X = α · (F / 2) ... Formula 8

However, α in the equation 8 is a variable that changes in proportion to the magnitude of the lateral acceleration G, and is expressed by the following equation 9.
α = (1+ | G | ・ K) Equation 9
Note that K in Expression 9 relates to roll control by the suspension ECU 21, and is a positive variable that can be changed by, for example, ride priority control or sports travel priority control selected by the driver.

  By the way, based on the relationship of the above formulas 6 to 9, the damping force Fi required for the inside shock absorber 11 (shock absorber 12) is always a positive value, and the shock absorber 12 (shock absorber 11) outside the turn is applied. The required damping force Fo always holds a negative value. Further, when the required damping force Fi for the shock absorber 11 (shock absorber 12) on the inner side of the turn and the required damping force Fo for the shock absorber 12 (shock absorber 11) on the outer side of the turn are added together, the total required damping required on the front wheel side. Force F. As described above, since the sign of the required damping force differs between the inside of the turn and the outside of the turn, the shock absorbers 11 and 12 can appropriately generate the damping force when the vehicle is turning.

  That is, by calculating the distribution amount X using the variable α that changes in proportion to the lateral acceleration G, when the vehicle is turning in the same direction, the shock absorber 11 (shock absorber 12) corresponding to the inside of the turn. The required damping force Fi is a positive value with a large absolute value, and the required damping force Fo of the shock absorber 12 (shock absorber 11) corresponding to the outside of the turn is a negative value with a small absolute value.

  Then, by using the variable α proportional to the lateral acceleration G, the total required damping force F required for the front wheels does not fluctuate, but the required damping force Fi required for the left and right shock absorbers 11 and 12 is not changed. , Fo can be appropriately changed according to the magnitude of the variable α. Therefore, when the vehicle turns, the shock absorbers 11 and 12 can each appropriately generate a damping force, and can reliably change the actual pitch angle θ generated in the vehicle body to the target pitch angle θah.

  In this way, the required damping force Fi is distributed to the shock absorbers corresponding to the inside of the vehicle turning to the left and right shock absorbers 11, 12, 13, and 14, and the required damping force Fo is applied to the shock absorber corresponding to the outside of the turning. After the distribution, the suspension ECU 21 proceeds to step S105.

  Here, in the situation where the total required damping force F is distributed between the left and right shock absorbers as described above, as long as the lateral acceleration G generated in the vehicle is acting in the same direction, it is also apparent from the above formulas 6-9. As described above, the required damping force Fi of the shock absorber 11 (or shock absorber 12) corresponding to the inside of the turn always increases, and the required damping force Fo of the shock absorber 12 (or shock absorber 11) corresponding to the outside of the turn is obtained. A relationship that always decreases is established. As a result, it is possible to prevent the actual pitch angle θ from increasing when the vehicle returns from the turning state to the straight traveling state.

  That is, since the required damping force Fi of the shock absorber 11 (or shock absorber 12) corresponding to the inside of the turn is always large, the vehicle body always rolls around the inside of the turn as a fulcrum in the turning state in the same direction. Therefore, since the vehicle height change accompanying the roll behavior can be reduced, it is possible to prevent the actual pitch angle θ from increasing when the vehicle returns from the turning state to the straight traveling state.

  In step S105, the suspension ECU 21 generates the required damping force Fi distributed by the shock absorber corresponding to the inside of the turn in step S104, and the shock absorber corresponding to the outside of the turn is distributed in the step S14. The drive circuits 28a, 28b, 28c, and 28d are driven and controlled so as to generate the required damping force Fo. Thereby, the rotary valves 11a, 12a, 13a, and 14a of the shock absorbers 11, 12, 13, and 14 change the flow path diameter of the working fluid, respectively. Therefore, the damping force generated by the shock absorbers 11, 12, 13, and 14 is matched with the required damping force Fi or the required damping force Fo, respectively, according to the turning direction of the vehicle.

  When the suspension ECU 21 appropriately changes the damping force of the shock absorbers 11, 12, 13, and 14, the process proceeds to step S106, and the execution of the roll control routine is terminated.

  Again, returning to the attitude control program shown in FIG. 3, the suspension ECU 21 determines in step S17 whether or not the vehicle is continuing the turning state. That is, the suspension ECU 21 inputs, for example, the lateral acceleration G detected by the lateral acceleration sensor 23 as in step S11, and the vehicle continues to turn based on the input lateral acceleration G value. It is determined whether or not.

  Then, the suspension ECU 21 determines “Yes” if the vehicle continues in the turning state, and executes each step processing after Step S14 again. On the other hand, if the vehicle is not in a turning state, in other words, if the vehicle is in a straight traveling state, the suspension ECU 21 determines “No”, proceeds to step S18, and temporarily ends the execution of the attitude control program. Then, after a predetermined short period of time, the suspension ECU 21 again starts executing the attitude control program in step S10.

  As can be understood from the above description, according to the first embodiment, the stroke amounts hfl, hfr, hrl, hrr of the shock absorbers 11, 12, 13, 14 at the time when the vehicle starts turning are used as reference strokes. It is possible to determine the amount, that is, the stroke reference point, and the actual pitch angle θ corresponding to the stroke reference point as the reference pitch angle θb. Then, the change amount of the actual pitch angle θ that changes with the vehicle height adjustment from the reference pitch angle θb, that is, the difference angle (θ−θb) can be determined as the offset amount J for correcting the target pitch angle θa. it can.

  In this way, by determining and using the offset amount J, the target pitch angle θa is changed synchronously in accordance with the change in the actual pitch angle θ accompanying the change in the vehicle height by the vehicle height adjustment, and the corrected target pitch angle is corrected. θah can be determined. In other words, since the target pitch angle θah can be appropriately determined according to the vehicle height change accompanying the vehicle height adjustment, the vehicle height can be adjusted even when the vehicle is turning, It is also possible to appropriately control the behavior of the roll that occurs with the turning. Thus, by determining the target pitch angle θah, the damping forces Fi and Fo of the shock absorbers 11, 12, 13, and 14 necessary for controlling the roll behavior are accurately determined, and the rotary valve 11a, 12a, 13a, 14a can be electrically controlled, and as a result, good steering stability can be ensured.

  Further, the suspension ECU 21 determines that the damping force Fi of the shock absorber disposed inside the turning is the damping force of the shock absorber disposed outside the turning according to the magnitude of the lateral acceleration G that changes as the vehicle turns. It can be controlled to be larger than Fo.

  More specifically, the suspension ECU 21 determines the total request that the shock absorbers 11, 12, 13, and 14 disposed in the front, rear, left, and right in order to realize the corrected target pitch angle θah. The damping force F can be calculated. Then, the suspension ECU 21 uses the total required damping force F in accordance with the magnitude of the lateral acceleration G. The damping force Fi of the shock absorber disposed inside the turning is the damping force Fo of the shock absorber arranged outside the turning. Can be distributed to be larger.

  As described above, when the damping force Fi of the shock absorber on the inside of the turn and the damping force Fo of the shock absorber on the outside of the turn are determined, the suspension ECU 21 determines the rotary valves 11a, 12a provided on the shock absorbers 11, 12, 13, 14 respectively. , 13a, 14a are electrically controlled. As a result, the shock absorber disposed inside the turning and the shock absorber arranged outside the turning can generate the determined damping forces Fi and Fo, respectively.

  As a result, in a vehicle turning in the same direction, the generation direction of the lateral acceleration G is always the same direction throughout the turning state. Therefore, the behavior of the roll can always be controlled using the shock absorber inside the turning as a fulcrum. . Therefore, the generation behavior of the roll generated in the vehicle body in the turning state can be made the same, in other words, the phase between the actual roll angle φ and the actual pitch angle θ can be made substantially the same, and the posture at the time of vehicle turning The change behavior can be made constant. In this way, by making the behavior of the posture change when turning the vehicle constant, the behavior of the roll can be controlled appropriately (more naturally), and the driving stability of the vehicle can be greatly improved. Can do.

  In addition, the total required damping force F required to control the roll behavior is proportional to the magnitude of the lateral acceleration G, and the damping force Fi of the shock absorber disposed inside the turning and the outside of the turning. Can be distributed to the damping force Fo of the shock absorber. At this time, the distribution amount X proportional to the magnitude of the absolute value of the lateral acceleration G is calculated, and the calculated distribution amount X is used as a shock absorber disposed inside the turn where the total required damping force F is evenly distributed. The damping force Fi of the shock absorber disposed inside the turning is smaller than the damping force Fo of the shock absorber disposed outside the turning by subtracting from the shock absorber disposed outside the turning. Can be bigger.

  Accordingly, it is possible to determine the damping forces Fi and Fo to be generated by the shock absorber disposed on the inner side of the swing and the shock absorber disposed on the outer side of the swing very precisely. Further, by adding or subtracting the distribution amount X proportional to the magnitude of the lateral acceleration G, for example, the total required attenuation required for the left and right absorbers 11 and 12 disposed on the front wheel side in order to control the behavior of the roll, for example. While generating the force F, it is possible to maintain a state in which the damping force Fi of the shock absorber disposed inside the turning is greater than the damping force Fo of the shock absorber disposed outside the turning. Therefore, by making the behavior of the posture change when turning the vehicle constant, the behavior of the roll can be controlled more accurately, and the steering stability of the vehicle can be greatly improved.

b. Second Embodiment In the first embodiment, the suspension ECU 21 calculates a distribution amount X proportional to the lateral acceleration G generated in the vehicle in accordance with the equations 8 and 9 by executing a roll control routine. The required damping force Fi of the shock absorber corresponding to the inside of the turn and the required damping force Fo of the shock absorber corresponding to the outside of the turn are calculated according to 6 and 7. Then, the suspension ECU 21 uses the rotary valves 11a, 12a, 13a, and 14a via the drive circuits 28a, 28b, 28c, and 28d so that the calculated requested damping force Fi and the requested damping force Fo are generated by the corresponding shock absorbers. The damping force of each shock absorber 11, 12, 13, 14 was controlled by operating continuously.

  On the other hand, it is possible to control the damping force of the shock absorbers 11, 12, 13, and 14 more simply. Hereinafter, the second embodiment will be described in detail.

  Also in the second embodiment, the suspension ECU 21 changes the damping force of each of the shock absorbers 11, 12, 13, and 14 in accordance with the magnitude of the lateral acceleration G generated in the vehicle detected by the lateral acceleration sensor 23. Control. However, in this second embodiment, the suspension ECU 21 controls the damping force of each shock absorber 11, 12, 13, 14 by changing it stepwise so as to have a predetermined change width, that is, the damping force. The rotary valves 11a, 12a, 13a, and 14a provided for the change determine the number of switching stages for switching the size of the flow path diameter of the working fluid in stages, and the shock absorbers 11 and 12 are set to the determined switching stage number. , 13, 14 to control the rotary valves 11a, 12a, 13a, 14a.

  Here, the number of switching stages of the rotary valves 11a, 12a, 13a, and 14a will be described. As schematically shown in FIG. 8, the number of switching stages has a plurality of switching stages (for example, 9 stages) and attenuates from the switching stage number where the damping force decreases as the absolute value of the detected lateral acceleration G increases. It changes to the number of switching stages where the force increases. Further, the change width of the damping force between the switching stages is set such that the change width of the shock absorber corresponding to the inside of the turn is large, and the change width of the shock absorber corresponding to the outside of the turn is set to be small. That is, in the shock absorber corresponding to the inside of the turn, even if the absolute value of the detected lateral acceleration G is small, the maximum number of switching steps at which the damping force is maximum is obtained. When the acceleration G is large, the maximum number of switching stages is obtained.

  In the second embodiment, the number of switching stages is proportional to the detected lateral acceleration G, that is, is changed linearly. However, in this case, the number of switching stages can be changed nonlinearly with respect to the change in the detected lateral acceleration G.

  Then, when the lateral acceleration G detected by the lateral acceleration sensor 23 is input, the suspension ECU 21 has a switching step number map in which the number of switching steps that changes in accordance with the magnitude of the lateral acceleration G is preset as shown in FIG. , The number of switching stages, that is, the required damping force of each shock absorber corresponding to the inside of the turn and the outside of the turn is determined.

  Incidentally, the sum of the damping force generated by the number of switching stages of the shock absorber corresponding to the inside of the turn and the damping force generated by the number of switching stages of the shock absorber corresponding to the outside of the turning is the total total required damping in the first embodiment described above. The variation range of the damping force between the number of switching stages is determined so as to be the force F. Thus, the suspension ECU 21 determines the number of switching steps for the shock absorber on the inside of the turn and the number of switching steps for the shock absorber on the outside of the turn, so that the total required damping force F is distributed to the left and right shock absorbers.

  Next, the determination of the number of switching stages described above will be specifically described by exemplifying the shock absorbers 11 and 12 on the front wheel side. When the suspension ECU 21 inputs the lateral acceleration G detected by the lateral acceleration sensor 23, the suspension ECU 21 determines the turning direction of the vehicle based on the sign of the input lateral acceleration G. That is, if the sign of the input lateral acceleration G is positive, since the vehicle is currently turning left, the suspension ECU 21 determines that the shock absorber 11 corresponds to the inside of the turn and the shock absorber 12 corresponds to the outside of the turn. To do.

  Then, the suspension ECU 21 refers to the switching step number map shown in FIG. 8, determines the switching step number Ni of the shock absorber 11 on the inside of the turn based on the absolute value of the input lateral acceleration G, and sets the shock absorber 12 on the outside of the turn. Determine the switching stage number. At this time, the switching stage number Ni inside the turning is larger than the switching stage number No outside the turning. In other words, the suspension ECU 21 requests a large damping force from the shock absorber 11 inside the turning, and requests a small damping force from the shock absorber 12 outside the turning.

  Therefore, also in the second embodiment, in order to control the roll angle φ generated in the vehicle body, the total required damping force F necessary for making the actual pitch angle θ coincide with the target pitch angle θah is generated in the vehicle. According to the lateral acceleration G, it is possible to appropriately distribute between the left and right shock absorbers 11 and 12 (or shock absorbers 13 and 14). Thereby, since the phase difference can be similarly changed between the turning state and the turning back state, the same effect as the first embodiment can be expected.

  In the second embodiment, when the detected lateral acceleration G is input from the lateral acceleration sensor 23, the suspension ECU 21 only refers to the switching step number map on the basis of the input lateral acceleration G, and the shock absorber on the inner side of the turn. In addition, the number of switching stages Ni and No of the shock absorber outside the turning can be determined. That is, as described in the first embodiment, it is not necessary to sequentially determine the required damping forces Fi and Fo by calculation processing. Therefore, the burden on the suspension ECU 21 can be reduced, and for example, problems such as heat generation due to an increase in the processing burden can be solved. Furthermore, in this case, for example, it is not necessary to provide a cooling means or the like in the suspension ECU 21, and the apparatus itself can be downsized.

  In carrying out the present invention, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the object of the present invention.

  For example, in each of the above embodiments, the suspension ECU 21 determines the required damping force Fi, Fo or the switching stage number Ni, No of each shock absorber 11, 12, 13, 14 according to the lateral acceleration G detected by the lateral acceleration sensor 23. Was determined and the damping force was controlled. On the other hand, for example, the required damping force Fi, Fo or the switching stage number Ni, No of each shock absorber 11, 12, 13, or 14 is determined according to the yaw rate generated in the vehicle, and the damping force is controlled. It is also possible to do. In this case, a yaw rate sensor that detects the generated yaw rate and outputs the detected yaw rate to the suspension ECU 21 may be provided. The yaw rate sensor may output a yaw rate generated when the vehicle turns left as a positive value, and output a yaw rate generated when the vehicle turns right as a negative value.

  Thus, even when using the yaw rate generated in the vehicle, the suspension ECU 21 calculates the distribution amount X using the variable α proportional to the magnitude of the absolute value of the yaw rate. The suspension ECU 21 calculates the required damping force Fi of the absorber corresponding to the inside of the turn and the required damping force Fo of the absorber corresponding to the outside of the turn, whereby the same effect as in the first embodiment can be obtained. Further, the suspension ECU 21 determines the switching stage numbers Ni and No according to the magnitude of the absolute value of the yaw rate, whereby the same effect as in the second embodiment can be obtained.

  Further, for example, the required damping force Fi, Fo of each shock absorber 11, 12, 13, or 14 or the number of switching steps Ni depending on the magnitude of the steering angle as the amount of turning operation of the steering handle that is turned by the driver. , No can be determined to control the damping force. In this case, it is preferable to provide a steering angle sensor that detects a steering angle that changes as the driver turns the steering handle and outputs the detected steering angle to the suspension ECU 21. The steering angle sensor outputs the steering angle as a positive value when the steering handle is turned leftward to turn the vehicle leftward, and when it is turned rightward to turn right The steering angle may be output as a negative value.

  Thus, even when the steering angle of the steering wheel is used, the suspension ECU 21 calculates the distribution amount X using the variable α that is proportional to the magnitude of the absolute value of the steering angle. The suspension ECU 21 calculates the required damping force Fi of the absorber corresponding to the inside of the turn and the required damping force Fo of the absorber corresponding to the outside of the turn, whereby the same effect as in the first embodiment can be obtained. Further, the suspension ECU 21 determines the switching stage numbers Ni and No according to the magnitude of the absolute value of the steering angle, whereby the same effect as in the second embodiment can be obtained.

  Furthermore, in the above embodiment, the target pitch angle θah is determined by offsetting the target map, that is, the target pitch angle θa, using the determined offset amount J. However, for example, even when the offset is performed using the offset amount J for which the actual pitch angle θ is determined, it is substantially the same, and it goes without saying that the same effect as in the above embodiment can be obtained.

1 is a schematic diagram illustrating a configuration of a vehicle attitude control device common to embodiments of the present invention. It is a figure for demonstrating the structure of the electric control apparatus of FIG. It is a flowchart of the attitude | position control program performed by suspension ECU of FIG. It is a figure for demonstrating determination of offset amount. 3 is a flowchart of a roll control routine executed by the suspension ECU of FIG. It is a graph for demonstrating the offset in the relationship between a roll angle and a pitch angle. It is a figure for demonstrating determination of the correct | amended target pitch angle. It is a figure for demonstrating the change of the switching stage number with respect to the change of the lateral acceleration in the shock absorber of inside of turning, and outside of turning, concerning 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Attitude control apparatus 11, 12, 13, 14 ... Shock absorber, 11a, 12a, 13a, 14a ... Rotary valve, 11b, 12b, 13b, 14b ... Air chamber, 20 ... Electric control apparatus, 21 ... Suspension ECU, 22 ... Height control ECU, 23 ... Lateral acceleration sensor, 24, 25, 26, 27 ... Stroke sensor, 28a, 28b, 28c, 28d, 29 ... Drive circuit

Claims (11)

In a vehicle attitude control device that controls the vehicle height by controlling the vehicle height adjustment function and damping force of a shock absorber that is disposed between the vehicle body and the wheel and has a function of adjusting the vehicle height.
A target pitch angle corresponding to an actual roll angle generated in the vehicle body is determined based on a correlation between a roll angle and a pitch angle set in advance to control a roll generated in the vehicle body as the vehicle turns. A target pitch angle determining means;
Target pitch angle correction means for correcting the target pitch angle determined by the target pitch angle determination means when the vehicle height is adjusted by the vehicle height adjustment function using the amount of change in the vehicle height;
A vehicle attitude control device comprising damping force control means for changing and controlling the damping force of the shock absorber in order to realize the target pitch angle corrected by the target pitch angle correction means. In the vehicle attitude control device according to claim 1,
The target pitch angle correcting means;
Stroke amount detection means for detecting the stroke amount of the shock absorber;
A reference stroke amount determining means for determining, as a reference stroke amount, a stroke amount detected by the stroke amount detecting means when the vehicle starts turning;
Reference pitch angle determining means for determining the actual pitch angle of the vehicle body corresponding to the reference stroke amount determined by the reference stroke amount determining means as a reference pitch angle;
The target pitch angle determined by the target pitch angle determining means is corrected with the difference between the actual pitch angle that changes as the vehicle is adjusted by the vehicle adjusting function and the reference pitch angle determined by the reference pitch angle determining means. A vehicle attitude control device comprising: an offset amount determining means that determines an offset amount for performing the operation. In the vehicle attitude control device according to claim 1,
The damping force control means is
Physical quantity detection means for detecting a predetermined physical quantity that changes as the vehicle turns,
In order to realize the target pitch angle corrected by the target pitch angle correcting means, the left and right shock absorbers disposed on the front wheel side of the vehicle and the left and right shock absorbers disposed on the rear wheel side of the vehicle cooperate. A total damping force calculation means for calculating the total damping force to be generated,
The total damping force calculated by the total damping force calculating means is converted into shock absorbers arranged inside the turning and shocks arranged outside the turning in accordance with a predetermined physical quantity detected by the physical quantity detecting means. And a total damping force distribution means for distributing the damping force of the shock absorber disposed on the inside of the swing larger than the damping force of the shock absorber disposed on the outside of the swing. And
The damping force of each shock absorber is changed and controlled based on the damping force of the shock absorber disposed inside the turn distributed by the total damping force distributing means and the damping force of the shock absorber disposed outside the turn. A vehicle attitude control device characterized by the above. In the vehicle attitude control device according to claim 3,
The total damping force calculating means includes
Calculate the actual pitch angle generated in the car body,
Calculating a difference value between the calculated actual pitch angle and the target pitch angle corrected by the target pitch angle correcting means;
A vehicle attitude control device that calculates a total damping force at which the calculated difference value is substantially “0”. In the vehicle attitude control device according to claim 3,
The total damping force distribution means includes:
The total damping force calculated by the total damping force calculating means is proportional to the predetermined physical quantity detected by the physical quantity detecting means, and the damping force of the shock absorber disposed inside the turning is arranged outside the turning. An attitude control device for a vehicle, characterized in that the distribution is made so as to be greater than a damping force of a shock absorber provided. In the vehicle attitude control device according to claim 5,
The total damping force distribution means includes:
The total damping force calculated by the total damping force calculating means is evenly distributed to the shock absorber arranged inside the turning and the shock absorber arranged outside the turning, and is detected by the physical quantity detecting means. The damping force distribution amount proportional to the predetermined physical quantity is added to the shock absorber disposed inside the turning, and subtracted from the shock absorber arranged outside the turning, and disposed inside the turning. The vehicle attitude control device distributes the damping force of the shock absorber to be larger than the damping force of the shock absorber disposed outside the turn. In the vehicle attitude control device according to claim 3,
The damping forces of the left and right shock absorbers disposed on the front wheel side and the rear wheel side are each switched in stages by a plurality of switching stages having a predetermined change width,
The total damping force distribution means includes:
The total damping force calculated by the total damping force calculating means is arranged on the outer side of the swing according to the predetermined physical quantity detected by the physical quantity detecting means. The number of switching stages of the shock absorber disposed inside the turning and the shock absorber arranged outside the turning is determined and distributed so as to be larger than the damping force of the shock absorber to be arranged. Vehicle attitude control device. In the vehicle attitude control device according to claim 7,
The predetermined change width of the damping force between the number of switching stages determined for the shock absorber disposed inside the turning is larger than the predetermined physical quantity change detected by the physical quantity detecting means. The predetermined change width of the damping force between the number of switching stages determined for the shock absorber disposed on the outer side of the turning is relative to the change of the predetermined physical quantity detected by the physical quantity detection means. A vehicle attitude control device having a small value. In the vehicle attitude control device according to claim 7,
The number of switching stages is
An attitude control device for a vehicle, wherein the vehicle attitude control device is determined in a linear or ratio-linear manner with respect to a change in the predetermined physical quantity detected by the physical quantity detection means. In the vehicle attitude control device according to claim 3,
The predetermined physical quantity detected by the physical quantity detection means is
An attitude control device for a vehicle, characterized in that it is at least one of a lateral acceleration generated as the vehicle turns, a yaw rate generated as the vehicle turns, and an operation amount of a steering wheel operated by a driver . In the vehicle attitude control device according to claim 1,
The shock absorber is
It is equipped with an electric actuator that is electrically controlled to change the damping force of the shock absorber.
The damping force control means is
An attitude control apparatus for a vehicle, wherein the damping force of the shock absorber is changed and controlled by electrically controlling the electric actuator.

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