JP2001047831A - Suspension control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure braking force by smoothly changing a wheel load at the time of full braking such as a case in which a front wheel abuts against a bumper rubber, in a vehicle in which reduction in the braking force acting on a vehicle from a rear wheel is restrained or prevented at the full braking. SOLUTION: When a full braking such as a case in which a front wheel abuts against a bumper rubber is detected from a time differential value of a vehicle body longitudinal acceleration for example, a pitch rigidity is increased by gradually increasing damping coefficient (c) with respect to a longitudinal speed component generated in a fluid pressure cylinder interposed between a rear wheel and the vehicle body, in accordance with a magnitude of an average longitudinal acceleration. Further, a wheel load fluctuation is smoothly connected, thereby preventing braking force of the rear wheel from decreasing rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of variably adjusting a speed input in a vertical direction, that is, a damping force with respect to a pitch speed input by an actuator such as a hydraulic cylinder interposed between each wheel and a vehicle body. For example, the present invention relates to a suspension control device capable of controlling pitch rigidity between front and rear wheels.

[0002]

2. Description of the Related Art There has been proposed a suspension control device capable of controlling pitch stiffness between front and rear wheels, for example, for suppressing a change in a vehicle body posture during braking of a vehicle.
In general, for example, during braking, the rear wheels tend to change to the extension side and the front wheels change to the compression side. Therefore, the pitch rigidity is increased by increasing the damping force of both, whereby the vehicle body sinks forward, that is, The nose dive and tail lift can be suppressed.

[0003] By the way, during such braking, the load on the front wheels increases and that on the rear wheels decreases. If the pitch stiffness is increased during braking as described above, the tendency becomes more remarkable. However, a reduction in rear wheel load means a reduction in road surface reaction torque during braking, and therefore a reduction in the braking force acting on the vehicle. Therefore, for example, when the braking force acting on the front wheels is maximally acting, the braking force acting on the vehicle as a whole is small. Further, for example, when the braking force acting on the wheel by the wheel cylinder becomes larger than the road surface reaction torque, the rear wheel tends to lock, and for example, the wheel cylinder pressure of the rear wheel is reduced by the anti-lock brake control device. Even when the braking force acting on the rear wheels is reduced, the braking distance may be slightly increased.

In order to solve such problems, the present applicant has previously proposed a suspension control device described in Japanese Patent Application Laid-Open No. H11-78464. This suspension control device detects sudden braking that occurs in the vehicle, and at the time of the sudden braking detection, reduces the rear wheel damping force and suppresses a significant decrease in the rear wheel load. The distance can be secured.

[0005]

However, simply reducing the damping force of the rear wheels during sudden braking, as in the conventional suspension control device, increases the amount of front wheel rebound and rear wheel rebound. If it is too large, the front wheels may be fully bound or the rear wheels may be fully rebounded, and abut on a so-called bumper rubber or rebound stopper. The bumper rubber or rebound stopper is usually a part of the strut or suspension link, but the bumper rubber or rebound stopper is intended to regulate the movement of the suspension so that it does not bounce or rebound further. After the front wheel abuts on the bumper rubber, the wheel load changes rapidly, and the braking force on the front wheel decreases due to excessive front wheel load.

The present invention has been developed in order to solve these problems. In particular, in the case of sudden braking in which the front wheels come into contact with the bumper rubber, the damping force of each wheel is increased so that the front wheels can be mounted on the bumper rubber. Abuts and suppresses sudden load movement from the rear wheel to the front wheel, thereby securing the braking distance, and increasing the damping force of the rear two wheels when sudden braking is released, thereby causing tail scut by swingback. It is an object of the present invention to provide a suspension control device capable of suppressing or preventing the occurrence of a suspension.

[0007]

In order to achieve the above object, a suspension control device according to the present invention is provided so as to prevent a reduction in braking force acting on a vehicle from wheels at the time of sudden braking. In the above vehicle, the damping force of each wheel with respect to the vertical input is made variable, and the damping force of each wheel is gradually increased at the time of sudden braking such that at least the front wheel is fully bound and abuts against the bumper rubber. Things.

According to a second aspect of the present invention, there is provided a suspension control device for preventing a decrease in a braking force acting on a vehicle from a wheel during sudden braking. An actuator interposed to generate a damping force according to the command value, a bumper rubber touch sudden braking detecting means for detecting sudden braking of the vehicle such that the front wheels are fully bound and abutting against the bumper rubber, and at least the bumper rubber Control means for increasing the damping force of each wheel stepwise when the sudden braking of the vehicle such that the front wheels contact the bumper rubber is detected by the touch sudden braking detection means. is there.

As described above, the front wheel does not directly contact the bumper rubber that regulates the movement of the front wheel suspension, but generally struts, suspension links, or a part of the shock absorber mechanism. Here, the expression that the front wheel comes into contact with the bumper rubber is used. According to a third aspect of the present invention, in the suspension control device according to the second aspect, the control means increases the damping force of each wheel as the deceleration of the vehicle generated by braking increases. It is characterized by doing.

According to a fourth aspect of the present invention, in the suspension control apparatus according to the second or third aspect, the control means is configured to detect a sudden braking of the vehicle by the sudden braking detecting means. A swing control means for temporarily increasing the damping force of each wheel even when it is released is provided. In the suspension control device according to claim 5 of the present invention, in the invention of claims 2 to 4, the actuator is configured to include a hydraulic cylinder, and the setting of the damping force is performed by the hydraulic cylinder. This is characterized in that it is performed by setting an attenuation coefficient for the generated vertical speed input.

[0011]

According to the suspension control apparatus of the first aspect of the present invention, the damping force of each wheel is increased stepwise during sudden braking when the front wheels come into contact with the bumper rubber. It is possible to suppress a sudden movement of the wheel load from the rear wheel to the front wheel after the front wheel comes into contact with the bumper rubber, and as a result, to prevent a sudden increase in the wheel load of the front wheel, And the braking distance acting on the vehicle can be secured.

According to the suspension control apparatus of the present invention, the damping force of the actuator interposed between each wheel and the vehicle body at the time of sudden braking such that the front wheel comes into contact with the bumper rubber. Step by step, it is possible to suppress rapid movement of the wheel load from the rear wheel to the front wheel after the front wheel comes into contact with the bumper rubber, and as a result, the wheel load of the front wheel rapidly increases This can secure the braking force acting on the vehicle from the front wheels to secure the braking distance.

According to the suspension control apparatus of the third aspect of the present invention, when the front wheel comes into contact with a bumper rubber during sudden braking, the larger the deceleration of the vehicle caused by the braking, the larger By increasing the damping force of the wheel, the change in the wheel load of the front wheel until the front wheel comes into contact with the bumper rubber becomes smooth, and the braking force acting on the vehicle from the front wheel can be stabilized accordingly.

According to the suspension control apparatus of the fourth aspect of the present invention, the tail scut due to swaying is suppressed by temporarily increasing the damping force of the rear two wheels when sudden braking is released. Can be prevented. According to the suspension control device of the present invention, the damping force of the actuator can be easily set by setting the damping coefficient for the vertical speed input generated in the fluid pressure cylinder.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a schematic configuration diagram of a vehicle showing a first embodiment in which a suspension control device of the present invention is developed into an active type suspension.
Denotes body side members, 11FL to 11RR denote front left to rear right wheels, and 12 denotes an active suspension. Note that this vehicle is equipped with an anti-lock brake control device (not shown) as described in, for example, Japanese Patent Application Laid-Open No. H10-315952. When the working fluid pressure to the wheel cylinder is reduced to reduce the braking force and the wheel speed is restored, the working fluid pressure to the wheel cylinder is gradually increased again, and this is repeated so that each wheel does not lock. While reducing the wheel speed without fail.

The active suspension 12 includes a vehicle body-side member 10 and wheel-side members 14 of wheels 11FL to 11RR.
, Fluid pressure cylinders 18FL to 18RR as actuators interposed therebetween, pressure control valves 20FL to 20RR for individually adjusting the working fluid pressures of these fluid pressure cylinders 18FL to 18RR, and pressure control valves 20
Supply working fluid of a predetermined pressure to FL to 20RR on supply side piping 21
S, and the pressure control valves 20FL-20
A fluid pressure source 22 for collecting a return fluid from the RR through a return pipe 21R, and a fluid pressure source 22 and a pressure control valve 2
The accumulator 24R inserted in the supply pressure side pipe 21S between 0FL and 20RR and each wheel 11 of the vehicle body side member 10
Is disposed FL~11RR side, the vertical acceleration sensor 28FL~28RR for detecting a vertical acceleration of the vehicle body each separately in each corresponding position, a vehicle speed sensor 27 for detecting the vehicle speed V _SP, the position of the center of gravity of the vehicle or longitudinal acceleration sensor 2 for detecting the longitudinal acceleration G _X that acts on the vicinity thereof
6, a brake switch 25 that outputs a brake switch signal S _BRK that is turned on when the brake pedal is depressed, and the vertical acceleration sensors 28FL to 28FL.
Based on the vertical accelerations G _{FL to} G _{RR of the RR,} the vehicle speed V _SP from the vehicle speed sensor 27, the longitudinal acceleration G _X from the longitudinal acceleration sensor 26, and the brake switch signal S _BRK from the brake switch 25, each of the pressure control valves 20FL to 20R
Control unit 30 for individually controlling the output pressure of R
And

Each of the fluid pressure cylinders 18FL to 18RR has a cylinder tube 18a, and a lower pressure chamber L formed by a piston 18c having a through hole in the axial direction is formed in the cylinder tube 18a. Then, a thrust is generated according to the pressure receiving area difference between the upper and lower surfaces of the piston 18c and the internal pressure. The lower end of the cylinder tube 18a is attached to the wheel side member 14, and the piston rod 18b
Is attached to the vehicle body side member 10. Each of the pressure chambers L is connected to the pressure control valve 2 via a fluid pressure pipe 38.
It is connected to output ports of 0FL to 20RR. In addition, each of the pressure chambers L of the fluid pressure cylinders 18FL to 18RR is connected to an accumulator 34 for absorbing unsprung vibration through a throttle valve 32. Also, the fluid pressure cylinder 1
Between the sprung and unsprung equivalents of each of 8FL to 18RR,
A coil spring 36 having a relatively low spring constant and supporting a static load on the vehicle body is provided.

Each of the pressure control valves 20FL to 20RR has a conventionally well-known three-port proportional electromagnetic pressure reducing valve (for example, having a proportional solenoid which is integrally provided with a housing in which a spool is slidably mounted). JP-A-64-7
No. 4111). By adjusting the command current i (command value) supplied to the excitation coil of the proportional solenoid, the fluid pressure source 22 and the fluid pressure cylinder 1 are adjusted.
The working fluid flowing between 8FL and 18RR can be controlled. Incidentally, the neutral control pressure to maintain the body in moderate condition and P _CN.

The vertical acceleration sensors 28FL-28
Each of _RR is a positive value in the upward acceleration G _{FL to} G _RR ,
For the downward accelerations G _{FL to} G _RR , a detection signal represented by a negative value is output. Further, the vehicle speed sensor 27 outputs a positive value and advance according to the magnitude of the longitudinal direction the speed of the vehicle, a detection signal expressed with have a negative value in the retracted as the vehicle speed V _SP. The longitudinal acceleration sensor 26 outputs a detection signal represented by a positive value in the forward direction and a negative value in the backward direction according to the magnitude of the longitudinal acceleration acting on or near the center of gravity of the vehicle.
Output as _X. In addition, the brake switch 25
Outputs a digital signal that becomes an ON state, for example, a logical value “1” when the brake pedal is depressed, and becomes a logical value “0”, for example, in the OFF state as the brake switch signal S _BRK .

As shown in FIG. 2, the control unit 30 includes the vertical acceleration sensors 28FL to 28FL.
A microcomputer 44 to which the vertical accelerations G _{FL to} G _RR output from the _RR are input, and pressure command values S _{FL to} S _{RR which} are D / A converted and output from the microcomputer 44 are supplied. Drive circuits 46FL to 46RR for converting these into drive currents i _{FL to} i _RR for the pressure control valves 20FL to 20RR are provided.

Here, the microcomputer 44 includes at least an input side interface circuit 44a, an output side interface circuit 44b, an arithmetic processing unit 44c including a micro process unit and the like, and a storage unit 44d having a RAM, a ROM and the like. Have. The input interface circuit 44a includes detection values G _FL -G _RR from the vertical acceleration sensors 28FL-28RR, a vehicle speed V _SP from the vehicle speed sensor 27, a longitudinal acceleration G _X from the longitudinal acceleration sensor 26, and a brake switch. The brake switch signal S _BRK is input from the output interface circuit 44b, and the pressure control valves 20FL to 20R are output from the output side interface circuit 44b.
Control command values S _{FL to} S _RR for R are output.

Next, a description will be given, with reference to the flow chart of FIG. 3, of the arithmetic processing for the integrated control of the active suspension executed by the microcomputer 44 of the control unit 30. This calculation process is executed as a timer interrupt process for each predetermined sampling time ΔT (for example, 10 msec.). Although no step for communication is provided in this arithmetic processing, the storage device 44d
Are always transmitted to a buffer or the like of the arithmetic processing unit 44c, and each calculation result calculated by the arithmetic processing unit 44c is also stored in the storage unit 44d as needed. Further, detection signals from the sensors and switches can be read at any time.

In this arithmetic processing, first, at step S01
By performing individual arithmetic processing, a bounce control amount F _Bi (i = FL〜) for controlling the bouncing of the vehicle body out of the fluid pressure control amounts given to the respective fluid pressure cylinders 18FL to 18RR of the active suspension. RR) is calculated and set. Specifically, for example, of the vertical accelerations G _{FL to} G _RR of the four vertical acceleration sensors 28 _{FL to} 28 _RR , a component for bouncing the vehicle body is extracted, and if necessary, the component is integrated into a speed component. further with or an integration to displacement component that, for example, the vehicle speed V _SP larger bounce motion suppression gain (acceleration component with increasing,
Velocity component and displacement component).
After multiplying this by each acceleration component, velocity component, and displacement component, the bounce control amount F _Bi is calculated and set from, for example, a weighted average sum thereof. Incidentally, by setting the bounce motion suppression gain to be larger as the vehicle speed increases, it is possible to achieve both a firm feeling and a sense of stability at the time of high-speed running and a riding comfort at the time of low-speed running.

Next, the flow proceeds to step S02 to perform individual arithmetic processing to control the roll of the vehicle body among the fluid pressure control amounts given to the fluid pressure cylinders 18FL to 18RR of the active suspension. Roll control amount F
Calculate and set _Ri . Specifically, for example, a roll moment (roll angular acceleration) acting on the vehicle body is obtained from the vertical accelerations G _{FL to} G _{RR of the} four vertical acceleration sensors 28FL to 28RR, and integrated as necessary. A velocity (or angular velocity) component, and a displacement (or phase) component obtained by integrating the velocity (or angular velocity) component.
_A roll motion suppression gain that increases with an increase in _SR is set for each component, and is multiplied by each component. Then, a roll control amount F _Ri is calculated and set from, for example, a weighted average sum of the components. Incidentally, by setting the roll motion suppression gain to be larger as the vehicle speed increases, it is possible to achieve both a firm feeling and a stable feeling at the time of high-speed running and a riding comfort at the time of low-speed running.

Next, the process proceeds to step S03, in which the vehicle body pitch of the fluid pressure control amounts given to the respective fluid pressure cylinders 18FL to 18RR of the active suspension is calculated in accordance with the individual arithmetic processing shown in FIGS. _Is calculated and set to control the pitch control amount F _Pi for controlling. Next, step S
04, by performing individual arithmetic processing, each actuator, that is, each fluid, from the bounce control amount F _Bi , the roll control amount F _Ri , and the pitch control amount F _Pi calculated in steps S01 to S03. Pressure cylinder 18F
It is calculated and set the total control amount F _i to L~18RR. Specifically, for example, weights K _B ,
K _R, sets the K _P, to the weighted average sum using them, calculates sets a total control amount F _i by the sum of the neutral position controlled variable F _N to achieve the neutral position. If the total control amount F _i exceeds the upper limit value for each actuator, for example, the weight K _B ,
Processing such as changing and setting K _R and K _P in accordance with the ratio of the magnitudes of the control amounts F _Bi , F _Ri and F _Pi may be performed.

[0026] and then proceeds to step S05, by performing the individual processing, after creating a control signal S _i in order to achieve the overall controlled variable F _i, returns to the main program. Specifically, each of the hydraulic cylinders 18
If the cylinder inner diameter of FL to 18RR is constant, each control amount (control force) is proportional to the supply fluid pressure, and the output pressure of each of the pressure control valves 20FL to 20RR is proportional to the supply current value. The control signal S _i for achieving the total control amount F _i according to the correlation is linearly determined by a certain proportionality constant. The driving circuit 4 according to the control signal S _i
The method of generating the command currents i _{RL to} i _RR from the 6FL to 46RR may be, for example, duty ratio control by PWM (Pulse Width Modulation) or a floating amplifier that amplifies the corresponding DC component.

Next, step S0 of the calculation processing of FIG.
The minor program executed in Step 3 will be described with reference to the flowchart of FIG. In this calculation processing, first, in step S1, individual calculation processing is performed to calculate and set the pitch suppression control amount F _GRi . Specifically, for example, the four vertical acceleration sensors 28FL to 28RR
The pitch moment (pitch angular acceleration) acting on the vehicle body is determined from the vertical accelerations G _{FL to} G _RR of the vehicle, and a pitch motion suppression gain that increases with an increase in the vehicle speed V _SP is set. Suppression control amount F _GPi
Is calculated and set. Incidentally, by setting the pitch motion suppression gain to be larger as the vehicle speed increases, it is possible to achieve both a firm feeling and a stable feeling at the time of high-speed running and a riding comfort at the time of low-speed running.

Next, the process proceeds to step S2, and
5 and pitch attenuation control according to the individual calculation processing of FIG.
Quantity F_VPiSet. Next, the process proceeds to step S3,
By performing another calculation process, step S1 is performed.
Pitch suppression control amount F calculated in step S2_GPi,pitch
Damping control amount F _VPiFrom each actuator, that is, each flow
Pitch control amount F to body pressure cylinders 18FL to 18RR_Pi
Is calculated and set, and then step S of the arithmetic processing in FIG.
Move to 04. Specifically, for example, the
Weight K₁, K_TwoAnd weighting using them
Pitch control amount F_PiIs calculated and set. In addition,
This pitch control amount F_PiExceeds the preset upper limit
In such a case, for example, the weight K₁, K_TwoFor each control
Quantity F_GPi, F_VPiChange according to the size ratio of
May be performed.

Next, step S2 of the calculation processing of FIG.
About the minor program executed by
This will be described using a chart. In this calculation process,
Pitch speed V in step S21_PIs calculated. Specifically
Is the vertical acceleration provided at the front left and right wheel parts, for example.
Vertical acceleration from the degree sensors 28FL, 28FR
G _FL, G_FRAnd the average value of the rear left and right wheels
Up and down from vertical acceleration sensors 28RL, 28RR
Direction acceleration G_RL, G_RRThe absolute value of the difference from the average
By integration, the pitch velocity V acting on the vehicle_PGet
be able to.

Next, the process proceeds to step S22, for example, by using whether or not a later-described bumper rubber touch rapid braking control flag _FBRT is set to a logical value "1".
It is determined whether or not the sudden braking of the bumper rubber touch is continuing. If the sudden braking of the bumper rubber touch is continuing, the process proceeds to step S23, and if not, the process proceeds to step S24.

At step S24, for example,
Normal rapid braking control flag F_NORIs a set of logical values "1"
Normal sudden braking is ongoing by using whether or not
It is determined whether or not there is, and normal rapid braking is ongoing
To step S25, otherwise, to step S25.
The process proceeds to Step S26. In the step S26,
Longitudinal acceleration G from longitudinal acceleration sensor 26_XTime derivative of
Value dG_X/ Dt is a relatively large absolute value set in advance
Negative predetermined value, ie, bumper rubber touch sudden braking predetermined value
G '_XBRTJudge whether it is below or not, at the time of the longitudinal acceleration
Differential value dG_X/ Dt is bumper rubber touch sudden braking place
Constant value G ' _XBRTIf it is less than or equal to
The process proceeds to step S27 otherwise.
You.

In step S27, the time differential value dG _X / of the longitudinal acceleration G _X from the longitudinal acceleration sensor 26 is calculated.
dt is small negative predetermined value preset relatively absolute value, i.e. determines whether or less usually sudden braking predetermined value G _'XNOR, the longitudinal acceleration time differential value dG _X / dt is usually sudden If it is equal to or _smaller than the predetermined braking value _G'XNOR , the process _{proceeds to} step S25, and if not, the process proceeds to step S28.

In step S23, the arithmetic processing shown in FIG. 6 described later is performed to set the damping coefficient c at the time of sudden braking of the bumper rubber touch, and then the flow proceeds to step S29. Further, in the step S25, the arithmetic processing of FIG. 9 described later is performed to set the damping coefficient c at the time of sudden braking of the bumper rubber touch, and then the process proceeds to the step S29.

In step S28, the rear left and right wheels
The steady-state mode predetermined value c ₀Before setting
The process moves to step S29. In the step S29
Is the pitch speed V for each set attenuation coefficient c._P
Is multiplied by the pitch attenuation control amount F for the rear left and right wheels._VPRL, F
_VPRR, And then in step S3 of the arithmetic processing in FIG.
Move to In this embodiment, the pitch for the front left and right wheels
Damping control amount F_VPFL, F_VPFRAre both "0".

Next, step S2 of the calculation processing of FIG.
6 will be described. In this calculation process, first, in step S231, the bumper rubber touch rapid braking control flag F _BRT is set to “1”, and at the same time, the normal rapid braking control flag F _NOR is reset to “0”. Subsequently, the flow shifts to step S232, where the vertical acceleration sensor 28R disposed at the rear right and left wheel portions is provided.
It is determined whether or not the average value of the vertical accelerations G _RL and G _RR from L and 28RR is “0” or more, and when the average value of the vertical accelerations G _RL and G _RR is “0” or more. To step S234, otherwise, to step S234.
Move to 233.

In step S234, FIG.
After setting the damping coefficient c according to the bumper rubber touch rapid braking tail lift mode control map of FIG.
Then, the process proceeds to step 29 of the calculation processing. On the other hand, in step S233, the tail scut mode release counter CNT is incremented, and then the flow shifts to step S235.

In step S235, it is determined whether or not the tail cut mode release counter CNT is equal to or greater than a predetermined value CNT ₀ (for example, “2” to “4”) corresponding to a relatively short time set in advance. If the tail cut mode release counter CNT is equal to or larger than the predetermined value CNT ₀ , the flow shifts to step S 236; otherwise, the flow shifts to step S 237.

In step S237, FIG.
Damping coefficient c according to the tail cut mode control map of
Then, the process proceeds to step 29 of the arithmetic processing in FIG. Further, in step S236, and shifts the tail squat mode cancellation counter CNT is cleared to "0" in step S238, step after resetting wherein the bumper rubber touch abrupt braking control flag F _BRT to "0" S239 Then, the damping coefficient c is set to the steady mode predetermined value c ₀ , and then the flow shifts to step 29 of the arithmetic processing in FIG.

Next, step S2 of the calculation processing of FIG.
The control map used in 34 will be described with reference to FIG. 7B. FIG. 7B is a damping coefficient setting control map for a tail lift period (mode) at the time of sudden bumper rubber touch braking. As is clear from the figure, the absolute value of the average value of the vertical accelerations G _RL and G _RR of the rear left and right wheels, that is, the pitch moment acting on the rear of the vehicle body (strictly, a couple component of the pitch input acting on the front of the vehicle body) And the pitch coefficient is obtained by dividing by the distance between the center of gravity of the vehicle and the distance between the rear axle). Here, when the pitch moment | (G _RL + G _RR ) / 2 | is smaller than the predetermined value G _R1 , a relatively small predetermined value c _{1 is} fixed, and conversely, the pitch moment | (G _RL + G _RR ) / 2 | relatively great predetermined value c ₁₀ constant when greater than G _R3, pitch moment _{| (G RL + G RR)} / 2 | when is between the predetermined value G _R1 and a predetermined value G _R3 are both intermediate predetermined Value c
₅ Constant. Incidentally, the intermediate predetermined value c ₅ is in the steady-state mode predetermined value c ₀ corresponds. Furthermore, the attenuation coefficient c is the certain relatively small predetermined value c ₁ constant, since the front wheels of the damping force is small, eventually the front wheel comes into contact with the bumper rubber (expresses this as bumper rubber touch), but the When the pitch moment | (G _RL + G _RR ) / 2 | is a predetermined value G _R2 , the pitch moment | (G _RL +
G _RR) / 2 | predetermined value G _R1 is smaller than the predetermined value G _R2, the predetermined value G _R3 is set at a value larger than the predetermined value G _R2.

Next, step S2 of the calculation processing of FIG.
The control map used in 37 will be described with reference to FIG. FIG. 8 is a damping coefficient setting control map for a tail cut period (mode) at the time of sudden braking of the bumper rubber touch. As can be seen from the figure, the intercept when the pitch moment | (G _RL + G _RR ) / 2 |, which is the absolute value of the average value of the vertical accelerations G _RL and G _RR of the rear left and right wheels, is “0” is The steady mode predetermined value c ₀ , and the damping coefficient c linearly increases with an increase in the pitch moment | (G _RL + G _RR ) / 2 |.

Next, step S2 of the calculation processing of FIG.
The arithmetic processing of FIG. What
This arithmetic processing is performed according to the method described in Japanese Patent Laid-Open No. 11-78464.
The logic described in Japanese Patent Publication No.
It has been further improved. In this calculation process, first, step S
251, the bumper rubber touch sudden braking control flag F
_BRTIs reset to “0”, and at the same time
F_NORIs set to “1”.

Next, the flow shifts to step S252, where the vertical acceleration sensor 28R disposed at the rear left and right wheel portions is provided.
It is determined whether or not the average value of the vertical accelerations G _RL and G _RR from L and 28RR is “0” or more, and when the average value of the vertical accelerations G _RL and G _RR is “0” or more. To step S254, otherwise, to step S254.
The process moves to 253.

In step S254, FIG.
After setting the damping coefficient c in accordance with the normal sudden braking tail lift mode control map of 0, the routine proceeds to step 29 of the arithmetic processing in FIG. On the other hand, in step S253, the tail scut mode cancel counter CNT is incremented, and then the flow shifts to step S255.

In step S255, it is determined whether or not the tail cut mode release counter CNT is equal to or larger than a predetermined value CNT ₁ (for example, “2” to “4”) corresponding to a relatively short time set in advance. If the tail cut mode release counter CNT is equal to or larger than the predetermined value CNT ₀ , the flow shifts to step S 256; otherwise, the flow shifts to step S 257.

In step S257, the damping coefficient c is set in accordance with the tail cut mode control map shown in FIG. 8, and then the flow shifts to step 29 of the arithmetic processing shown in FIG. In step S256, the tail scut mode release counter CNT is cleared to "0", and the process proceeds to step S258. Here, the normal sudden braking control flag F _NOR is reset to "0", and then the process proceeds to step S259.
Then, the damping coefficient c is set to the steady mode predetermined value c ₀ , and then the flow shifts to step 29 of the arithmetic processing in FIG.

Next, step S2 of the calculation processing of FIG.
The control map used in 54 will be described with reference to FIG. FIG. 10 is a damping coefficient setting control map for the normal sudden braking tail lift period (mode). As can be seen from the figure, the vertical accelerations G _RL , G of the rear left and right wheels
_The damping coefficient c is changed according to the absolute value of the average value of _RR , that is, the magnitude of the pitch moment acting on the rear of the vehicle body.
Here, the intercept when the pitch moment | (G _RL + G _RR ) / 2 | is “0” is the steady mode predetermined value c ₀ , and the pitch moment | (G _RL + G _RR ) / 2 | The attenuation coefficient c also decreases linearly.

Next, the operation of the arithmetic processing of FIG. 5 will be described with reference to FIGS. If a braking force is applied to the wheels during braking, the vehicle body tends to keep moving forward due to inertia. In practice, this does not separate the wheels from the vehicle body, so that a pitch moment as described above is generated. At this time, for example, the upward acceleration acting on the rear part of the vehicle body becomes (1-ΔG) as shown in FIG.
[G] (Gravity: gravitational acceleration) (slightly different from the vertical acceleration described above), the decreasing rear wheel load variation ΔW is given by the following equation.

ΔW = mΔG + c∫ΔG + k∬ΔG (1) where ∫ is a time integration symbol, m is mass, c is a damping coefficient, and k
Is the elastic modulus. The rear wheel braking force f accompanying the wheel load fluctuation is expressed by the following two equations. f = μ (W−ΔW) (2) where μ is a road surface friction coefficient and W is a rear wheel load in a neutral state.

Therefore, the greater the amount of change .DELTA.W in rear wheel load toward the decreasing side described above, the smaller the rear wheel braking force f. In FIG. 12, a portion described as a linear region corresponds to this. As is clear from FIG. 6, in this linear region, the larger the wheel load, the larger the braking force. If the wheel load becomes too large, for example, the viscoelasticity decreases due to the deformation of the tire, etc., and even if the wheel load becomes larger, the braking force becomes smaller. This region is called a non-linear region, and the threshold value of the wheel load with the linear region is expressed as a linear region upper limit threshold _WLNR . Also, originally, if the wheel load decreases, the braking force should also decrease linearly, but as mentioned above, the road surface reaction torque decreases when the wheel load decreases, so that the wheel cylinder acts on the wheel. The braking force becomes relatively large, and the wheels tend to lock, whereas the anti-lock brake control device described above reduces the working fluid pressure to the wheel cylinders, so that the braking force decreases significantly. . This area is the anti-lock brake (ABS in the figure)
The threshold of the wheel load with the linear region is referred to as the linear region lower limit threshold W _{ABS as the} operating region.

If the damping coefficient c in the above equation (1) is the above-mentioned steady mode predetermined value c ₀ and the wheel load change amount ΔW _ORG is generated by the vertical acceleration ΔG at the time of a certain sudden braking, the wheel load change amount Due to the amount ΔW _ORG , the wheel load W _{ORG to} be reached becomes smaller than the linear region lower limit threshold value W _ABS and enters the anti-lock brake operation region. Therefore, the braking force f at that time is as shown by f _ORG in FIG. It becomes an extremely small value. Therefore, for example, when the braking force of the front wheels reaches the maximum value in the linear region, the total braking force acting on the vehicle decreases, and as a result, the braking distance may be increased.

On the other hand, since the pitch moment is a force, the greater the braking force acting on the vehicle, that is, the greater the deceleration, the greater the pitch displacement. Looking at this over time, as shown in FIG. 13, for normal braking, as is rapid braking, deceleration, i.e. the can rises early in the negative direction of the longitudinal acceleration G _X I understand. And, in the case of bumper rubber touch sudden braking having a larger pitch displacement than normal sudden braking, the longitudinal acceleration G is further increased.
_X rises quickly in the negative direction. Therefore, the arithmetic processing of Fig. 5, in step S24, manner of change of the longitudinal acceleration G _X, i.e. longitudinal acceleration time differential value dG _X / dt
If it is less than or equal to the predetermined negative bumper rubber touch sudden braking predetermined value G ′ _XBRT having a relatively large absolute value, the _{process proceeds} to step S23 in FIG. The damping coefficient c at the time of the rubber touch sudden braking is set. Further, the longitudinal acceleration time differential value dG _x / d
Even t is not less bumper rubber touch sudden braking predetermined value G _'XBRT, in step S27 in the figure, the longitudinal acceleration time differential value dG _X / dt is small negative normal steep that preset relatively absolute value It is determined whether or not the braking value is equal to or less than a predetermined braking value G ′ _XNOR , and the longitudinal acceleration time differential value dG _X / dt is determined.
Is less than or equal to the normal sudden braking predetermined value _G'XNOR , the routine proceeds to step S25, where the damping coefficient c during normal sudden braking is set.

The arithmetic processing of FIG. 9 executed in step S25 of the arithmetic processing of FIG. 5 is a modification of the logic described in Japanese Patent Application Laid-Open No. 11-78464 as described above in accordance with the present embodiment. Therefore, its operation will be briefly described here. In this calculation process, the average value of the vertical acceleration of the rear left and right wheels still under braking
Since ((G _RL + G _RR ) / 2) is an upward positive value, the flow shifts to step S 254, where the predetermined value for steady state c according to the pitch moment | (G _RL + G _RR ) / 2 | ₀
A smaller damping coefficient c for the tail lift mode during normal sudden braking is set. According to this small damping coefficient c, as shown in FIG. 12, the wheel load change amount ΔW _CRT-R1 generated even with the same vertical acceleration ΔG is smaller than the wheel load change amount ΔW _ORG at the time of the steady-state damping coefficient c _0. According to the wheel load change amount ΔW _CRT-R1 , if the reached wheel load W _CRT-R1 stays in a linear region larger than the linear region lower threshold W _ABS , the braking force acting on the vehicle body from the rear wheels at that time. f
_It becomes much larger than _CRT-R1 , and the braking force f _CRT-R1 acting on the vehicle body from the rear wheels works effectively, and as a result, the braking distance can be secured.

When the sudden braking is released, for example, the vehicle body is pushed back backward by the reaction force of the front wheels stored with respect to the pitch moment, so that a so-called tail scutting occurs. At this time, the acceleration generated at the rear portion of the vehicle body, that is, the average value of the vertical accelerations of the rear left and right wheels ((G _RL + G _RR ) / 2) is a negative value indicating a downward direction. from through steps S255 and proceeds to step S257, where pitch moment _{| (G RL + G RR)} / 2 | damping coefficient c for large tail squat mode than the constant for a given value c ₀ according to is set. That is, when the sudden braking is released and a pitch moment that causes a tail scut is generated, the damping force of the rear wheel is quickly increased, so that the actual tail scut due to the swing back can be prevented from being suppressed. Further, since the reacting roll converges in a relatively short period of time by the large rear wheels damping force at a predetermined value CNT ₀ to the tail squat mode cancellation counter CNT is incremented at step S253 corresponds to the relatively short period of time When counting up, the process proceeds to step S256 after the step S253 of the calculation processing of FIG. 9, normally disengaged from rapid braking control routine, sets the attenuation coefficient c in the next step S259 steady for a given value c _0.

On the other hand, during sudden braking of the bumper rubber touch
Indicates that the attenuation coefficient c is set by the arithmetic processing of FIG.
It is. In this calculation process, the rear left and right wheels
Average value of vertical acceleration ((G_RL+ G_RR) / 2) is upward
Since the value is a positive value, the process proceeds to step S234, where
As shown in FIG. 7b, the pitch moment | (G_RL+ G
_RR) / 2 | according to the bumper rubber touch
The damping coefficient c for the lift mode is set. I mentioned earlier
As in the case of bumper rubber touch sudden braking, vehicle deceleration
Is rapidly and greatly increased, so that the pitch moment
G | (G_RL+ G_RR) / 2 | also increases rapidly and significantly,
As a result, the relatively large predetermined value G_R3More than. Obedience
In the tail lift period (mode),
Then, the pitch moment | (G_RL+ G_RR) / 2 | increase
At the same time, the attenuation coefficient c is equal to the predetermined value c.₁, C_Five, C_Tenof
It will be set so that it becomes larger gradually. This
Wheel load change due to the damping coefficient c (strictly speaking, its absolute
Value) ΔW appears as shown by the solid line in FIG.
The pitch model that changes equivalently to the longitudinal acceleration during braking shown in FIG.
-Ment | (G_RL+ G_RR) / 2 |
It will increase once and decrease. In FIG.
The wheel load change of the normal suspension characteristics is shown by the dotted line.
The dashed line indicates the attenuation coefficient c by the ratio
A relatively small predetermined value G_R1Wheel load change when fixed to
is there. As described above, the attenuation coefficient c is set to the relatively small predetermined value.
Value G_R1Is fixed to the pitch moment | (G_RL
+ G_RR) / 2 | is the predetermined value G_R2When the bumper
Contact with the rubber, and thereafter, the wheel load change ΔW
Increase. In contrast, in the present embodiment, the attenuation coefficient
c is the pitch moment | (G_RL+ G_RR) / 2 | increase
Together with the predetermined value c₁, C_Five, C _TenIn order of
As a result, the low damping force shown by the broken line
The wheel load change amount ΔW changes smoothly, and
Suppresses the transfer of load from the wheel to the front wheel, and the wheel load on the front wheel increases rapidly
To prevent the braking force from dropping due to
Secure braking force acting on these vehicles to secure braking distance
Can be

Further, the sudden braking is released, and
When the reciprocation accompanied by the cut occurs, the calculation processing of FIG.
Similarly, the average value of the vertical acceleration of the rear left and right wheels ((G
_RL+ G_RR6) is a negative value indicating a downward direction.
In the calculation processing of, the pitch moment |
(G_RL+ G_RR) / 2 |₀Yo
The damping coefficient c for the larger tail cut mode is set.
The damping force of the rear wheel is quickly increased,
It is possible to prevent the actual tail scut by return
it can. In addition, this rebound is caused by the large rear wheel damping force.
Therefore, since the convergence is performed in a relatively short time, the aforementioned step S2
The tail cut mode incremented by 33
The release counter CNT has a predetermined value corresponding to the relatively short time.
Value CNT ₁When counting up, the calculation process of FIG.
The process proceeds from step S233 to step S236 and thereafter,
Deviated from the bumper rubber touch braking control routine, the next
In step S239 of FIG.₀To
Set.

As described above, the brake switch 25 and the longitudinal acceleration sensor 26 and the step S of the arithmetic processing in FIG.
26 constitutes the bumper rubber touch sudden braking detection means of the present invention, and similarly, the entire arithmetic processing of FIG. 5 including the arithmetic processing of FIG. 6 constitutes the control means, and similarly, steps S233 and S233 of the arithmetic processing of FIG. Step S237 constitutes the swing control means.

Next, a second embodiment of the suspension control device of the present invention will be described. The main configuration of the vehicle in this embodiment is the same as that in FIGS. 1 and 2 of the first embodiment. The main control of the active suspension is the same as that shown in FIGS. 3 and 4 of the first embodiment. On the other hand, the arithmetic processing as the minor program of the arithmetic processing of FIG. 4 is changed from that of FIG. 5 to that of FIG. However, the calculation processing of FIG. 14 is similar to the calculation processing of FIG. 5 described above, and some of them have the same steps. Therefore, the same reference numerals are given to the same steps, and the detailed description thereof will be omitted. The difference between the calculation processing of FIG. 5 and the calculation processing of FIG. 14 is that step S23 is replaced with step S23 ′ and that step S26 is replaced with step S2.
6 ', the step S27 is changed to a step S27'.

More specifically, in step S23 ', since the minor program to be executed there is changed,
As will be described later, in step S26 ', it is determined whether the pressure reduction time of the anti-lock brake control per rear wheel unit rotation is equal to or greater than a predetermined value of the bumper rubber touch sudden braking, and the pressure reduction time is determined by the bumper rubber touch. If it is equal to or greater than the predetermined value, the process proceeds to step S23 ', and if not, the process proceeds to step 27'.

In step S27 ', it is determined whether the pressure reduction time of the anti-lock brake control per unit rotation of the rear wheels is equal to or longer than a predetermined value for normal sudden braking. If so, the process proceeds to step S25; otherwise, the process proceeds to step S28. Further, the arithmetic processing as a minor program executed in step 23 'is changed from that of FIG. 6 of the first embodiment to that of FIG. However, the arithmetic processing in FIG. 15 is similar to the arithmetic processing in FIG. 6 described above, and some of them have the same steps. Therefore,
The same steps are denoted by the same reference numerals, and their detailed description is omitted. The difference between the calculation processing of FIG. 6 and the calculation processing of FIG.
34 '. In this step S234 ', the control map of the tail lift mode damping coefficient c during bumper rubber touch sudden braking set in accordance with the pitch moment | (G _FL + G _FR ) / 2 | is changed to that shown in FIG. 16B. I have. Here, pitch moment |
When (G _RL + G _RR ) / 2 | is smaller than the predetermined value G _R1 , the relatively small predetermined value c _{1 is} fixed. Conversely, when the pitch moment | (G _RL + G _RR ) / 2 | is larger than the predetermined value G _R3 a relatively large predetermined value c ₁₀ constant. When the pitch moment | (G _RL + G _RR ) / 2 | is between the predetermined value G _R1 and the bumper rubber touch predetermined value G _R2 , the predetermined value c _{4 which} is slightly smaller than the steady mode predetermined value c _0. Constant and the pitch moment | (G _RL +
When (G _RR ) / 2 | is between the bumper rubber touch predetermined value G _R2 and the predetermined value G _R3 , the predetermined value c _{7 which} is slightly larger than the steady mode predetermined value c ₀ is fixed.

Next, the operation of the present embodiment will be described. As described above, when the rear wheel load decreases during sudden braking,
The braking force (torque) becomes larger than the road surface reaction torque of the tire, and the rear wheels tend to lock. Then, the wheel cylinder pressure of the rear wheel is reduced by the anti-lock brake control device, the rear wheel braking force is forcibly reduced, and the wheel speed is restored. The tendency is that the more the sudden braking is performed, the larger the reduction amount of the rear wheel load is.
As described in JP-A-15952, the anti-lock brake control device is designed to reduce the braking force of the rear wheels.
The time for reducing the rear wheel cylinder pressure is prolonged. For example, if the front wheel touches the bumper rubber,
Since the degree of the sudden braking is the largest, the wheel cylinder pressure reduction time per unit rotation of the rear wheel by the anti-lock brake control device is long. Further, the wheel cylinder pressure reduction time per unit rotation of the rear wheel is longer at the time of rapid braking than at the time of normal braking, although not as much as the front wheel bumper rubber touch sudden braking. Therefore, two thresholds are set for the pressure reduction time by the anti-lock brake control device per unit rotation of the rear wheel, that is, a predetermined value for bumper rubber touch rapid braking and a predetermined value for normal rapid braking, and the pressure reduction time is set for the bumper rubber. If the touch sudden braking is equal to or more than the predetermined value, the process shifts from step S26 'to step S23' of the calculation processing in FIG. 14 to set the damping coefficient c at the time of the bumper rubber touch sudden braking, and the decompression time is less than that and If it is equal to or greater than the normal sudden braking predetermined value, the flow shifts from step S27 'to step S25 in FIG. 14 to set the damping coefficient c during normal sudden braking. Note that the decompression time of the antilock brake control device is normally monitored in the control device, and may be read as needed.

On the other hand, when the bumper rubber touch is suddenly braked, the damping coefficient c is set by the arithmetic processing of FIG. 15, and especially in the tail lift period (mode), the damping coefficient c is set according to the control map of FIG. Is set.
In this embodiment, the pitch moment | (G _RL + G _RR )
/ 2 |, the damping coefficient c increases with the predetermined value c ₁ ,
c _4, c _7, in the order of c ₁₀ would be set to be gradually increased in three steps. The wheel load change amount (strictly, the absolute value) ΔW based on the damping coefficient c is shown in FIG.
As shown by the solid line in FIG. 13, the pitch moment | (G _RL +
G _RR ) / 2 | once increases and decreases. The wheel load variation of the usual suspension characteristics in FIG. 16a by a two-dot chain line shows a wheel load variation amount when the fixed damping coefficient c a relatively small predetermined value G _R1 in broken lines, in this embodiment , Damping coefficient c is the pitch moment | (G _RL +
G _RR ) / 2 | with predetermined values c ₁ , c ₄ , c ₇ , c
Because it was set to gradually increase in three stages in the order of _10, the wheel load change Δ
W changes more smoothly, the load movement from the rear wheel to the front wheel is suppressed by that much, the reduction of the braking force due to the sudden increase in the wheel load of the front wheel is prevented, and the braking force acting on the vehicle from the front wheel is reduced. Power can be secured and a braking distance can be secured.

As described above, the brake switch 25, the longitudinal acceleration sensor 26, and step S26 'of the calculation processing of FIG. 14 constitute the bumper rubber touch sudden braking detection means of the present invention. 14 constitute the control means, and steps S233 and S237 of the arithmetic processing in FIG. 15 constitute the swing control means.

Next, a third embodiment of the suspension control device of the present invention will be described. The main configuration of the vehicle in this embodiment is the same as that in FIGS. 1 and 2 of the first embodiment. The main control of the active suspension is the same as that shown in FIGS. 3 and 4 of the first embodiment. On the other hand, the arithmetic processing as the minor program of the arithmetic processing of FIG. 4 is changed from that of FIG. 5 to that of FIG. However, the arithmetic processing in FIG. 17 is similar to the arithmetic processing in FIG. 5 described above, and some of them have the same steps. Therefore, the same reference numerals are given to the same steps, and the detailed description thereof will be omitted. The difference between the calculation processing of FIG. 5 and the calculation processing of FIG. 17 is that step S23 is replaced with step S23 ″ and step S26 is replaced with step S2.
6 ", and step S27 is changed to step S27".

More specifically, in step S23 ", since the minor program to be executed there is changed,
As will be described later, in step S26 ", it is determined whether or not the number of gentle pressure increases during the pressure reduction control of the anti-lock brake control is equal to or less than a predetermined value of the bumper rubber touch sudden braking. If the value is equal to or less than the predetermined value, the process proceeds to step S23 ". Otherwise, the process proceeds to step 27".

In step S27 ", it is determined whether the number of gentle pressure increases during the pressure reduction control of the antilock brake control is equal to or less than a predetermined value of the normal sudden braking. If the difference is equal to or less than the predetermined value, the process proceeds to step S25, and if not, the process proceeds to step S28. The arithmetic processing as the minor program executed in step 23 ″ is the same as that of the first embodiment. 18 of FIG. 6 has been changed to that of FIG. However, the calculation processing of FIG. 18 is similar to the calculation processing of FIG. 6, and some of them have the same steps. Therefore, the same reference numerals are given to the same steps, and the detailed description thereof will be omitted. The difference between the calculation processing in FIG. 6 and the calculation processing in FIG. 18 is that step S234 is performed in step S23.
4 ". In this step S234",
The control map of the tail lift mode damping coefficient c at the time of sudden braking of the bumper rubber touch set according to the pitch moment | (G _FL + G _FR ) / 2 | has been changed to that shown in FIG. 19B. Here, the pitch moment | (G _RL
When + G _RR ) / 2 | is larger than the predetermined value G _R3 , the relatively large predetermined value c _{10 is} fixed. When the pitch moment | (G _RL + G _RR ) / 2 | is smaller than the predetermined value G _R1 , the steady mode predetermined value c ₀ is used as an intercept and the pitch moment | (G _RL + G _RR ) / 2 | is a predetermined value. G _R1
The decreased linearly as a relatively small predetermined value c ₁ when, pitch moment _{| (G RL + G RR)} / 2 |
Is between the predetermined value G _R1 and the relatively large predetermined value G _R3 , linearly increases from the predetermined value c ₁ to the predetermined value c ₁₀ .

Next, the operation of the present embodiment will be described. For example, in the anti-lock brake device described in Japanese Patent Application Laid-Open No. Hei 10-315952, as described above, for example, the rear wheels fall into a locking tendency with a decrease in the rear wheel load at the time of sudden braking, and the rear deceleration state after the deceleration state When the wheel speed is restored by reducing the wheel cylinder pressure, the wheel cylinder pressure must be increased again to reduce the wheel speed. At this time, if the wheel cylinder pressure is rapidly increased again in a state where the wheel cylinder pressure is reduced to recover the wheel speed that has fallen into the lock tendency, the lock tendency may be repeated immediately, Generally, the wheel cylinder pressure is gradually increased. The gradual pressure increase after the pressure reduction is generally performed by gradually increasing the wheel cylinder pressure in short cycles. On the other hand, as described above, since the rear wheel load decreases during sudden braking, the anti-lock brake control device generally reduces the rear wheel cylinder pressure by reducing the rear wheel cylinder pressure. Therefore, the faster the braking, the longer the pressure reduction time of the rear wheel cylinder pressure by the anti-lock brake control device, and the shorter the pressure increase time, the shorter the pressure increase time. The number of pressure increase steps (hereinafter simply referred to as the number of slow pressure increase) is also small. For example, when the front wheel touches the bumper rubber, the degree of sudden braking is the largest, so the number of times of gradual pressure increase during pressure reduction control by the antilock brake control device is small. Further, even if the braking is not as sharp as the front wheel bumper rubber touch sudden braking, the number of times of the gradual pressure increase during the pressure reduction control is small in the case of the rapid braking as compared with the normal braking. Therefore, two thresholds, namely, a predetermined value of the bumper rubber touch rapid braking, are set for the number of times of gentle pressure increase during the pressure reduction control by the antilock brake control device,
A predetermined value for normal rapid braking is set, and when the number of gentle pressure increases during the pressure reduction control is equal to or smaller than the predetermined value for bumper rubber touch rapid braking, the process proceeds from step S26 "to step S23" of the calculation processing in FIG. Then, the damping coefficient c at the time of the bumper rubber touch sudden braking is set, and if the decompression time is shorter than the predetermined value and the normal sudden braking is equal to or less than the predetermined value, the process proceeds from step S27 "of FIG. The damping coefficient c at the time of sudden braking is set, and the number of gradual pressure increase (the number of steps) during the pressure reduction control of the antilock brake control device is as follows.
Usually, it is monitored in the control device, so that it can be read as needed.

On the other hand, when the bumper rubber touch is suddenly braked.
The attenuation coefficient c is set by the arithmetic processing of FIG.
It is set during the tail lift period (mode).
The attenuation coefficient c is set according to the control map of 19b.
In this embodiment, the pitch moment | (G_RL+ G_RR)
/ 2 | increases, the damping coefficient c increases
Constant value c₀From the predetermined value c₁Until it became smaller steplessly
Later, the predetermined value c_TenIs set to grow steplessly until
Will be. Wheel load change due to such damping coefficient c
The quantity (strictly, its absolute value) ΔW is shown by a solid line in FIG.
The longitudinal acceleration during braking shown in FIG.
Pitch moment | (G _RL+ G_RR) / 2
With |, it increases once and decreases. In this FIG.
Two-dot chain line shows the change in wheel load of normal suspension characteristics
And the damping coefficient c is relatively small_R1Fixed to
The amount of change in the wheel load at the time is shown by a broken line, but in this embodiment,
The decay coefficient c is the pitch moment | (G_RL+ G_RR) / 2 |
With the increase of
, So that the reduction shown by the broken line
Wheel load change ΔW is more smooth than that of damping
Changes, and the load transfer from the rear wheels to the front wheels is reduced accordingly.
And the braking force due to the sudden increase in the front wheel load
To prevent the vehicle from lowering and confirm the braking force acting on the vehicle from the front wheels.
To maintain the braking distance.

As described above, the brake switch 25, the longitudinal acceleration sensor 26, and the step S26 "of the calculation processing of FIG. 17 constitute the bumper rubber touch sudden braking detection means of the present invention. 17 constitute the control means, and Steps S233 and S237 of the arithmetic processing of FIG. 18 constitute the swing control means.

In the above embodiments, the damping force is controlled by adjusting the damping coefficient. However, the damping force may be controlled by adjusting the spring constant acting on the damping force. Further, the damping force on the rear wheel side generated at the time of sudden braking is the extension side, and the damping force of the rear wheel generated at the time of its release, that is, at the time of swingback, is the compression side. It may be just the side.

In the above-described embodiment, the case where a microcomputer is applied as the control unit 30 has been described. Alternatively, an electronic circuit such as a counter and a comparator may be combined. In the above embodiment, the case where the front wheel comes into contact with the bumper rubber has been described. However, the embodiment may be applied to the case where the rear wheel comes into contact with the rebound stopper when extended.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an entire vehicle configuration showing an example of an active suspension in which a suspension control device of the present invention is developed.

FIG. 2 is an explanatory diagram of a configuration of a control unit in FIG. 1;

FIG. 3 is a general flowchart of active suspension control executed by the control unit of FIG. 2;

FIG. 4 is a flowchart showing a minor program executed in the calculation processing of FIG. 3;

FIG. 5 is a flowchart of a first embodiment of a minor program executed in the calculation processing of FIG. 4;

FIG. 6 is a flowchart showing a minor program executed in the calculation processing of FIG. 5;

7 is a control map used in the calculation processing of FIG. 6 and an explanatory diagram of its operation.

FIG. 8 is a control map used in the calculation processing of FIGS. 6 and 9;

FIG. 9 is a flowchart illustrating a minor program executed in the calculation processing of FIG. 5;

FIG. 10 is a control map used in the calculation processing of FIG. 9;

FIG. 11 is an explanatory diagram of wheel load movement during braking.

FIG. 12 is an explanatory diagram illustrating a relationship between a wheel load and a braking force.

FIG. 13 is an explanatory diagram of a temporal change in longitudinal acceleration due to a difference in a braking state.

FIG. 14 is a flowchart of a minor program executed in the calculation processing of FIG. 4 according to a second embodiment;

FIG. 15 is a flowchart showing a minor program executed in the calculation processing of FIG. 14;

16 is a control map used in the calculation processing of FIG. 15 and an explanatory diagram of its operation.

FIG. 17 is a flowchart of a third embodiment of the minor program executed in the calculation processing of FIG. 4;

FIG. 18 is a flowchart illustrating a minor program executed in the calculation processing of FIG. 17;

19 is a control map used in the calculation processing of FIG. 18 and an explanatory diagram of its operation.

[Explanation of symbols]

 12 is an active suspension 10 is a vehicle body side member 11FL-11RR is a wheel 14 is a wheel side member 18FL-18RR is a hydraulic cylinder 20FL-20RR is a pressure control valve 22 is a hydraulic pressure source 25 is a brake switch 26 is a longitudinal acceleration sensor 27 is Vehicle speed sensor 28FL-28RR is a vertical acceleration sensor 30 is a control unit

Claims (5)

[Claims] In a vehicle in which a reduction in braking force acting on a vehicle from a wheel during sudden braking is suppressed, a damping force of each wheel with respect to a vertical input is variable, and at least a front wheel is fully bound so that a bumper rubber is provided. A suspension control device characterized in that the damping force of each wheel is increased in a stepwise manner at the time of sudden braking that comes into contact with the vehicle. 2. A vehicle in which a braking force acting on a vehicle from a wheel during sudden braking is prevented from being reduced, a damping force corresponding to a command value is generated by being interposed between each wheel and the vehicle body. An actuator, bumper rubber touch sudden braking detection means for detecting sudden braking of the vehicle such that the front wheel is fully bound and abuts on the bumper rubber, and at least the front wheel abuts on the bumper rubber with at least the bumper rubber touch sudden braking detection means. And a control means for increasing the damping force of each wheel stepwise when sudden braking of the vehicle is detected. 3. The suspension control device according to claim 2, wherein the control means increases the damping force of each wheel as the deceleration of the vehicle generated by braking increases. 4. The control device according to claim 1, wherein the sudden braking detection unit detects a sudden braking of the vehicle, and then, when the braking is released, temporarily increases the damping force of each wheel. The suspension control device according to claim 2 or 3, wherein the suspension control device is provided. 5. The actuator according to claim 1, wherein the actuator includes a hydraulic cylinder, and the damping force is set by setting a damping coefficient with respect to a vertical speed input generated in the hydraulic cylinder. 5. The suspension control device according to any one of 2 to 4.