JPH02171310A - Suspension damping force control device - Google Patents

Abstract

PURPOSE:To control damping force smoothly and increase comfortability in driving, by subtracting the amount of damping force to be lowered for suppressing up-and-down vibration from a target damping force obtained from the force applied on a vehicle and driving a valve means to meet that result, in a cylinder and piston type titled device. CONSTITUTION:Output signals from a steering wheel turning angle sensor 55, vehicle speed sensor 56, longitudinal direction accelerating sensor 38 and lateral direction accelerating sensor 57 are input into a main CPU 60, and a target damping force for suppressing variation in vehicle height is calculated using a force applied onto a vehicle body. On the other hand, vibration applied onto the vehicle body is detected by vibration sensors 41 to 44, input into a sub- controller 51, and the amount of damping force to be lowered for suppressing the up and down vibration is calculated. The amount of damping force to be lowered is subtracted from the target damping force by the sub-CPU 40 and the driving of the valve means for shock absorbers 1 to 4 is controlled using that result. With this constitution, a suspension can be controlled smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to suspensions, and in particular to determining the damping force of suspensions. The present invention relates to a combination of a shock absorber and a controller that sets the damping force of the shock absorber in accordance with the force exerted on the vehicle body.

(Prior art) In order to suppress the propagation of wheel vibrations (especially shocks) to the vehicle body and provide a comfortable ride for vehicle occupants, the suspension is equipped with a shock absorber.The damping force of the shock absorber If it is set low, the propagation of wheel vibration to the vehicle body is reduced, so passengers feel soft movement when the wheels vibrate and the ride is comfortable. Due to relatively fast turn steering (rotation of the steering wheel) at high speeds, the vehicle body tilts forward (nose down) or backward (nose up).
, when a force that causes the vehicle to lean to the left or right is applied, the vehicle body tends to tilt in this manner, and the lower the damping force, the greater this tendency becomes, resulting in poor handling stability.

Therefore, the stain absorber is equipped with a rotary valve that changes the area of the fluid passage between the two chambers divided by the piston in the cylinder to be large or small.

It is designed to selectively switch to a plurality of positions such as standard (intermediate) and soft (large aperture) (for example, Japanese Patent Laid-Open No. 194609/1983). According to this, for example, when making the ride comfortable, it is possible to set the vehicle to a soft setting, and to perform sudden braking, sudden acceleration, relatively fast turning steering at relatively high speeds, etc. relatively frequently. An appropriate damping force can be selected depending on the road condition and driving condition by setting it to hard sometimes, and setting it to standard when neither can be determined definitively.

However, recently there has been a strong demand for automatic vehicle attitude control, and the damping force required to maintain the vehicle attitude suitable for driving is calculated in accordance with the vehicle speed, steering angle, etc. Techniques have been proposed to automatically set this damping force to the stain absorber (for example, Japanese Patent Laid-Open No. 59-1
68039). That is, a detection means for detecting a force applied to the vehicle body that causes a change in the load applied from the vehicle body to the wheels, and a detection means for detecting a force applied to the vehicle body that causes a change in the load applied from the vehicle body to the wheels, and a detection means for detecting a force applied to the vehicle body relative to the wheel due to a change in the force applied to the vehicle body in response to a detected value of the detection means. An automatic damping force control device is provided that includes a control means for calculating a target damping force for suppressing changes in the height of the shock absorber and setting the target damping force to the shock absorber.

[Problem to be solved by the invention]

However, although the magnitude of the force that causes a change in attitude of the vehicle body that occurs during driving is linear (stepless), the damping force setting of the shock absorber is set in one step such as hard, standard, and soft as mentioned above. Therefore, damping force control (i.e., vehicle body posture control) according to driving conditions lacks smoothness.

Also, for example, when the vehicle is turning, the damping force is maintained hard, and the damping force is set and maintained regardless of road conditions such as uneven road surfaces, and the vibrations (shocks) of the wheels are hard and propagate to the vehicle body, resulting in poor ride comfort. Unfortunately, there is a problem in that ride comfort is sacrificed due to vehicle body posture control.

The present invention enables smoother damping force control according to driving conditions to ensure handling stability, and also during damping force control to ensure handling stability.

The purpose is to improve riding comfort as much as possible.

[Structure of the invention]

(Means for solving problems) A damping force control device for a suspension according to the present invention.

A cylinder (12), a piston (14) that divides the inner space of the cylinder (12), a rod (10) fixed to the piston (14) and extending to the outside of the cylinder (12),
Valve means (32) that can be moved substantially steplessly and that defines the degree of communication opening between the spaces (15, 16) that produce a pressure difference due to the vertical movement of the piston (14), and the valve means (32).
) to determine the degree of flow opening (3g)
a shock absorber (1) having: an electric biasing means (49) for biasing said electrical means (38); a force applied to the vehicle body resulting in a change in the load applied from the vehicle body to the wheels;
Detection means for detecting (55-5111.65-6
8); In response to the detection values (Rs, Vs, Rg, Pg) of the detection means (55-58.65-6g), suppress changes in the height of the vehicle body relative to the wheels due to changes in the force applied to the vehicle body. First calculation means (6) for calculating the target damping force (ATdf)
0); Vibration detection means (Ill, 39) that detects vertical vibration of wheels or vehicle body; Vibration detection means (41, 39)
a second calculation means (40) for calculating a damping force reduction amount (Avdf) for suppressing vertical vibration of the vehicle body in accordance with the detected value (Vg);
) minus the damping force reduction amount (Avd[')
valve drive control means (49) for instructing the urging means (49) to drive the valve means (32) to the position corresponding to
40); It should be noted that the symbols in parentheses are attached to corresponding points or corresponding values in the embodiments shown in one drawing and described later.

(Function) First, the shock absorber (+, ) is a valve means that can be moved substantially steplessly and that defines the degree of communication opening between the spaces (15, 16) that create a pressure difference due to the vertical movement of the piston (I4). (32), and the damping force is determined by this flow opening (large opening: low damping force, small opening: high damping force)
Therefore, the damping force can be set steplessly (linearly).

In addition, detection means (55 to 5
8, 65-68); and the height of the vehicle body relative to the wheels due to changes in the force applied to the vehicle body, corresponding to the detected values (R8, Vs, Rg, Pg) of the detection means (55-58°65-68). The present invention includes a first calculation means (60) for calculating a target damping force (ATdf) that suppresses changes in the vehicle's posture, thereby suppressing changes in the posture of the vehicle caused by forces applied to the vehicle body in response to driving conditions, as in the past. The damping force control for this purpose can be realized by calculating the target damping force (ATdf) more precisely than before and setting it to the shock absorber, that is, more precisely and smoothly than before.

The present invention further includes a vibration detecting means (/II, 39) for detecting vertical vibration of the car roof or the car body: the vibration detecting means (4
1°39) to calculate the amount of damping force reduction (Avdf) for suppressing the vertical vibration of the vehicle body.
calculation means (40); and the target damping force (ATd
The value obtained by subtracting the damping force reduction amount (Avdf) from f) (
valve drive control means (49) for instructing the urging means (49) to drive the valve means (32) to the position corresponding to
40) Since the system is equipped with the following, the damping force is lowered when the vibrations of the wheels or the vehicle body are strong, even during the damping force control for suppressing changes in vehicle posture due to the force applied to the vehicle body in response to driving conditions. Conversely, if the vibration is weak, the damping force is increased, achieving damping force control that provides as good a ride as possible. Since the shock absorber can linearly set the damping force, the target damping force (ATdf) for suppressing changes in vehicle attitude can be set.
) and damping force reduction amount (Avdf) to improve riding comfort
It is possible to precisely calculate the damping force (ATdl) corresponding to the situation at the time, calculate a damping force (ATdl) that precisely reflects both, and set this in the shock absorber (1). That is, it is possible to simultaneously suppress changes in vehicle posture and improve vehicle ride comfort, precisely and smoothly.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(Example) FIG. 1 shows an example of the present invention. The suspension of the front right wheel of the vehicle (not shown) is equipped with a shock absorber.
1, a shock absorber 2 is attached to the front left wheel suspension (not shown), and a shock absorber 2 is attached to the rear right suspension (not shown).
(not shown) has a shock absorber 3, and a rear left I
The X-wheel suspension (not shown) is equipped with a shock absorber 4, and the damping force of these shock absorbers 1-4 is controlled by sub-controllers 51-5, respectively.
It is set at 4.

First, the structure of the shock absorber l will be explained.

FIG. 2a shows an enlarged longitudinal section of the shock absorber 1. Figure 52b shows a further enlarged longitudinal section of a portion.

The upper ends of an inner cylinder 12 and an outer cylinder 13 are fixed concentrically to an upper end base II through which a piston rod 10 that supports the vehicle body passes. A screw 14 is fixed to the lower end of the piston rod 10. The lower end of the outer cylinder 13 is fixed to a lower end base 18, while the lower end of the inner cylinder 12 is fixed to a valve device 17 supported by the lower end base 18.

The inner space of the inner cylinder 12 is divided into two spaces 1 by the piston 14.
5 and an upper space 16. Space between the valve device 17 and the lower end base 18 (lower end base space) 18a
The inner and outer cylinders 12 and 13 communicate with the open space, that is, the outer space 24, through a flow passage in the lower part of the valve gear 17. A liquid is sealed inside the inner cylinder 12. The outer space 24 is filled with liquid and gas.

The valve iq [17 has an upper space 16 and a lower end base space 1
A communication passage 19° 22 is formed between the two passages 8a, and the first set of passages 19 is an opening on the upper space 16 side and is pressed down by a compression coil spring 21. It is closed by a disc-shaped check valve member 20. The second set of flow passages 22 is an opening on the lower end base space 18a side, and is closed by a check valve member 23 pushed up by a leaf spring 23a.

When the wheels are pushed up due to unevenness on the road surface, a force acts between the cylinder 12 and the piston 14 in a direction that causes the piston 14 to move downward relative to the cylinder 12, causing the piston 14 to move downward. attempts to move relatively downward,
The pressure in the upper space 16 increases. When this pressure exceeds a predetermined value, the check valve member 23 is driven downward against the push-up blade of the leaf spring 23a, and the pressure in the inner space 16 is reduced to the flow path 22 of the second Jfl and the lower end space. Space 18a
It passes through to the outside space 24. As a result, piston 1
4 becomes possible to move upward, and the piston 14 moves downward. This prevents the piston rod 10 (vehicle body) from being pushed up due to the pushing up of the wheels.

When the wheels descend due to uneven road surfaces.

A force acts between the cylinder 12 and the piston 14 in a direction that causes the piston 14 to move upward relative to the cylinder 12, and the piston 14 tends to move upward relative to the cylinder 12, causing pressure in the upper space 16. decreases. When this pressure becomes less than a predetermined value, the check valve member 20 is driven upward against the pressing blade of the compression coil spring 21, and the pressure in the outer space 24 is reduced to the lower end base space 18a and the first set. It exits into the upper space 16 through the flow passage 19 . This allows the piston 14 to move upward, and the piston 14 moves upward. As a result, the descent of the piston rod 10 (vehicle body) due to the descent of the wheels is tifred.

As explained above. The damping force when the wheel is pushed up and the damping force when the wheel is lowered by the valve device 17 is generated by the flow passages 22 and 19.
Since the cross-sectional area of the flow path is fixed.

It is fixed.

Next, to explain the mechanism for providing a variable damping force provided for carrying out the present invention, the rod 10 is hollow and the lower end thereof passes through the piston rod 10 in the vertical direction. Internal lower space (27, 28
) communicates with the upper space 16 through the passage port 10a of the rod. The internal lower space of the piston rod IO (27,
28), a cup-shaped bottomed cylinder 25 having an air-tight flange 26 at the center of la is inserted, and its upper opening edge is fixed to the inner wall of the rod 10. This cylinder 25
The inner lower space of the piston rod 10 (27,
28) is upper space! 6, and an inner rod upper space 27 that communicates with the upper space 15 through communication ports 29, which are six holes equally spaced in the circumferential direction on the side wall of the rod 10. It is sectioned.

In the side wall of the bottomed cylindrical body 25, six holes 30 are formed above the flange 26, and six holes 31 are formed below the flange 26 at equal intervals in the circumferential direction.

The lower surface of an end plate 25a, which is a ring-shaped magnetic material, is in contact with the upper opening end surface of the bottomed cylinder 25, and the end plate 25a presses the bottomed cylinder 25 downward. It is fixed to the rod 10 by. A bobbin 38a around which an electric coil 38 is wound is disposed on the end plate 25a. The lower large diameter portion of the magnetic plunger 32 enters the bottomed cylinder 25, and the upper narrow diameter portion of the plunger 32 vertically penetrates the end plate 25a.

A ring-shaped groove 35 is formed in the lower diameter portion of the plunger 32, and this groove 35 allows two flanges 33.
4 are formed, and these flanges 33 and 34 are in contact with the inner surface of the bottomed cylinder 25. The width (vertical direction) of the ring-shaped groove 35 extends from the upper end to the lower end of the upper and lower holes 30 and 31 of the bottomed cylindrical body 25. The upper end surface of the upper narrow diameter portion of the plunger 32 is an inverted conical tapered surface, and the central portion thereof is an inverted conical tapered surface.

A round hole is formed to accommodate the compression coil spring 36. The coil bobbin 38a has a nail-shaped magnetic core 37.
is inserted, and its lower leg end is.

It has a conical shape complementary to the tapered surface of the plunger 32, and has a round hole in its center for receiving the upper end of the compression coil spring 36.

When the electric coil 38 is de-energized, the plunger 32 is pushed down by the repulsive force of the compression coil spring 36.
As shown in FIG. 2b, the two grooves 35 completely communicate with the entire hole 31, but since the flange 33 almost closes the hole 30 with a small gap, the upper space 15 - hole 29 - inside the rod. The cross-sectional area of the flow path between the upper and lower spaces (15-16) that takes the route of upper space 27 - hole 30 - groove 35 - hole 31 - rod inner lower space 28 - communication port 10a - upper space 16 is It is the lowest and piston I4 is difficult to move. That is, the damping force (adjustable damping force) determined by the plunger 32 is the highest value of the damping force that can be set by the plunger 32.

The electric coil 38 is energized, and the plunger 32 is attracted to the core 37 and reaches the top (the plunger 32 contacts the core 37).
When the holes 30 and 31 are each completely communicated with the groove 35, the cross-sectional area of the communication passage between the upper and lower spaces (15-16) becomes the maximum, and the piston 14 is easy to move, i.e. , the damping force determined by the plunger 32 (
The adjustable damping force) is the lowest value of the damping force that can be set with the plunger 32.

The magnetic core 37 (lower end shape), the plunger 32 (upper end shape), the compression coil spring (spring constant), and the electric coil 38 (winding length, common length, and winding thickness) are It is designed so that the distance of the plunger 32 to the magnetic core 37 is approximately proportional to the f1 current value, and 1! The distance of the plunger 32 with respect to the magnetic core 37 is determined by the current value of the magnetic coil 38;
In other words, the adjustable damping force is determined.

Note that the structures of the other shock absorbers 2 to 4 shown in FIG. 1 are also substantially the same as the structure of the shock absorber 1. The above-mentioned damping force adjustment mechanism consisting of the plunger 32, etc.
It may be equipped on the valve gear [17]. Further, a fixed damping force mechanism including the flow passages 19, 22 of the valve device 17, etc. may be configured in the piston 14. Alternatively, a damping force adjustment mechanism such as the plunger 32 may be installed in the current valve device 17, and a fixed damping force mechanism consisting of the flow passages 19, 22, etc. of the current valve device 17 may be configured in the piston 14. good.

Referring again to FIG. 1, the electric coils 38 of the shock absorbers 1-4 are provided with sub-controllers 51-51, respectively.
54 is energized. The sub-controllers 51 to 54 have substantially the same configuration and control the current flowing through the electric coil 38 using substantially the same logic.

The piston rods 10 of the shock absorbers 1 to 4 include
Vibration sensors 41 to 44 that generate analog voltages representing the amplitude of vertical vibration, that is, vibration detection voltages are coupled to each of them, and the vibration detection voltages generated by the vibration sensors 41 to 44 are connected to signal processing interfaces of subcontrollers 51 to 54, respectively. Given to 39. Note that the vibration sensors 41 to 44 may be coupled to other members coupled to the piston rod 10 or to the vehicle body.

The interface 39 includes a low-pass filter that receives a vibration detection voltage, and a vibration detection voltage that suppresses high-frequency noise with the low-pass filter, which is first differentiated to obtain an analog voltage that indicates vibration speed, and which is second-order differentiated to indicate vibration acceleration. It includes a differentiation circuit that generates an analog voltage, and an absolute value circuit that generates a voltage that represents the absolute value of vibration acceleration, that is, a vibration acceleration absolute value signal.
), that is, a vertical vibration acceleration signal Vg, is applied to an A/D conversion input port AD of a microprocessor (hereinafter referred to as CPU) 40.

A rotation angle sensor 55 for detecting the rotation angle of the steering wheel is coupled to the steering shaft of a vehicle equipped with the embodiment shown in FIG. to the processing interface 65. The interface 65 includes a differentiation circuit that differentiates an analog voltage representing the rotation angle to generate an analog voltage representing the rotation speed of the steering shaft, that is, a rotation speed signal Rs.
s is given to the A/D conversion input capo-1-ADI of the CPU 60.

Pulses generated by a rotary encoder 56 coupled to the vehicle speed meter cable and generating electrical pulses at a frequency proportional to the rotational speed of the transmission output shaft are provided to a signal processing interface 66 . The interface 66 includes an F/V conversion circuit, and supplies a voltage at a level proportional to the frequency of the electric pulse, that is, a vehicle speed signal Vs, to the CPtJ6.
0 to the A/D conversion input port AD2.

The vehicle body is equipped with an acceleration sensor 57 that detects lateral acceleration (so-called lateral G) of the vehicle body and generates an analog voltage indicative of the acceleration, and the analog voltage is applied to a signal processing interface 67 . interface 67
includes an absolute value circuit that generates a voltage representing the absolute value of the analog voltage, that is, a lateral acceleration absolute value signal Rg, and supplies the lateral acceleration absolute value signal Rg to the A/D conversion input port AD3 of the CPU 60.

The vehicle body has acceleration in the longitudinal direction of the vehicle body (so-called longitudinal G).
An acceleration sensor 58 is mounted that detects and generates an analog voltage indicative of the detection, and the analog voltage is applied to a signal processing interface 68. The interface 68 includes an absolute value circuit that generates a voltage indicating the absolute value of the analog voltage, that is, a longitudinal acceleration absolute value signal Pg.
The longitudinal acceleration absolute value signal pg is given to the A/D variable input boat AD4 of the CPU 60.

A potentiometer 81 for instructing the damping force adjustment "Wf" is connected to the main controller 70.

The CPU 60's A/
An analog voltage indicating a 14W plate, that is, an adjustment value (, ffi, Aa) is applied to the D conversion input port AD5.

Also to the main controller 70. A switch 83 for instructing on (execution)/off (stop) of automatic damping force adjustment is connected, and a signal representing the instruction (H: execution of automatic damping force adjustment/L: stop) is sent to the input port A+s of the CPU 60. )give.

The ROM 62 of the main controller 70 contains a program that performs damping force control to suppress changes in vehicle body posture (front/rear inclination, lateral inclination, etc.) due to changes in vehicle driving conditions, as well as programs for calculating damping force, which will be described later. A data group and various data to be referenced for this purpose are stored. The CPU 60 reads various signals Rs, vs, Rg, and Pg obtained based on the detection values of the various sensors 55 to 58 described above into the internal RAM or external RAM 61 at a predetermined period, and calculates the target damping force. This is set in the latches of data output circuits 71-74. Data output images 1I871-74 output latch data to sub-controllers 51-54 via buffer amplifiers. The decoder 59 of the main controller 70 converts the element designation data of the address data output by the CPU 60 into an element designation signal, and provides the designation signal to the designated element. The CPU 60 sends operation control signals for each element to the control line.

In the ROM 45 of the sub-controllers 51 to 54.

Even if there is vertical vibration in the wheel, which will be described later, the piston rod 10
A program to perform damping force reduction control to suppress the vibration of the rod 10, a program to set the damping force of the shock absorbers 1 to 4 to the calculated required damping force, and a calculation of the damping force reduction amount for suppressing the vertical vibration of the rod 10. A data group and various data to be referred to are stored. C
The PU 40 outputs the vertical vibration acceleration absolute value signal Vg obtained based on the detection values of the vibration sensors 41 to 44 described above and the data output images 1st to 54 of the main controller 70.
The eye fB damping force data (Rout) given by is read into the internal RAM or external RAMJ6 at a predetermined period, and the damping force to be set for the shock absorber, that is, the required damping force (
ATdl) is calculated, and this is converted to the current value to be energized to the electric coil 38 (in this embodiment, the energizing current value is determined by 1 energizing duty control, so 5 energizing duty specifically), and the current value is calculated. Duty on (energization)/off (de-energization) corresponding to the power current value is applied to the coil driver 49 via the output interface (buffer amplifier) 48 . The coil driver 49 connects the electric coil 38 and the output end of a constant voltage power supply circuit (not shown) when instructed to turn on, and cuts off this connection when instructed to turn off.

The current value of the electric coil 38 is a time series average value.

IfX(Ts-Td)/Ts. Note that Ts is the length of one cycle of duty control (
time), Td is the length (time) of non-energization (off) within the one cycle, and (Ts - Td) is the length (time) of energization (on) within one cycle, If is the energizing current I''1 when energized continuously for one cycle Ts. The decoder 47 of the subcontrollers 51 to 54 converts the element designation data of the address data output by the CPU 40 into an element designation signal. Convert it.

A signal indicating that the specified element has been specified is given.

The CPU 40 sends operation control signals for each element to the control line.

In FIG. 3a, CP tJ60 of the main controller 70 is shown.
The control operation is shown below. When the CPU 60 is powered on (step 1: hereinafter, only the step number or subroutine number will be indicated, omitting the words "step" or "subroutine" in parentheses), a message indicating Wait! ! l(
The signal level or data that should be output when damping force control is stopped is output, and internal registers, timers, counters, etc. are set to the contents that should be set during standby (2). Then, in order to determine the sampling period (and updating of the target damping force?ii, calculation period) dT for reading the detection values of the various sensors 55 to 58, a timer clT that takes a time limit of dT is started (3).
, the detected values, etc. are read (4). That is, analog voltages Pg (absolute value of acceleration in the longitudinal direction of the vehicle body), Rα (absolute value of lateral acceleration of the vehicle body), VA (vehicle speed), Rs (absolute value of acceleration in the lateral direction of the vehicle body) of the A/D conversion input ports ADI to AD5, Rotation speed) and 8a (damping force adjustment amount) are converted into digital data and stored in registers PG, RG, and V, respectively.
S, RS and A A write, and input port Al
11 signal level (H:] Decaying force control execution L: Stop) is written to register AM.

Next, the CPU 60 determines the damping force adjustment amount corresponding to Vs (vehicle speed) and Rs (steering wheel rotation speed),
That is, the change in lateral acceleration corresponding to the rate of change in the turning radius of the vehicle that is expected to occur due to VA and Rs;
A damping force adjustment amount Erdf suitable for suppressing changes in the lateral inclination of the vehicle body that would occur due to the above is calculated (5).

The details of this calculation operation are shown in FIG. 3b. A memory area (Table 1) in the ROM 62 contains information at various rotational speeds (Rs) of the steering wheel. Vehicle speed (Vs
) The corresponding damping force adjustment standard value data (Erg) are written in groups according to rotational speed (R, s), so the CPU 60 reads the rotational speed Rs (contents of register R3).
to specify the group (one of the curves in Figure 3b), and set the vehicle speed V
s (contents of register vS) is the individual data within the group Er
Specify a.

This individual data ErIH is read from table 1 of the ROM 62 (51). Then, the read data Erg is multiplied by a coefficient value (weighting coefficient) K1 that determines the contribution ratio with other damping force adjustment amounts, which will be described later, to obtain Vg (vehicle speed) and Rs.
A damping force adjustment amount E rdf is obtained for suppressing a change in lateral inclination caused by an estimated lateral acceleration corresponding to a rate of change in the turning radius of the vehicle that is expected to occur due to (rotational speed of the steering wheel) (52).

Referring again to FIG. 3a, the primary CPU 60 is.

damping force adjustment amount corresponding to the longitudinal acceleration absolute value P,
That is, a damping force adjustment amount Apdf suitable for suppressing the longitudinal tilt of the vehicle body caused by Pg is calculated (6).
.

The contents of "rApdf calculation" (6) are shown in Figure 3c.
In the memory area (Table 2) of the ROM 62, damping force adjustment amount standard value data (A
pg) is written.

The CPU 60 specifies the acceleration absolute value Pg in the longitudinal direction (contents of the register PC) and the adjustment standard value data Apg associated therewith, and reads this individual data APg from the table 2 of the ROM 62 (61). . Then, the damping force adjustment amount Apdf for suppressing the longitudinal tilt caused by Pg (absolute value of acceleration in the longitudinal direction) is calculated as follows (62).

Apdf=Kp1・[KP2・Apg+Kpa (Ap
a-Apgp)) Kp+: Coefficient value that determines the contribution ratio (distribution ratio) with other damping force adjustment amounts ρ2: Coefficient KP3 of the proportional term of PI (proportional/derivative) control
:Coefficient APfl of the differential term of PI (proportional/derivative) control
P: Before dT, damping force adjustment standard value data Ap (register 8 PG) read from Table 2 corresponding to Pg.
Contents of P) (Apg - Apgp): Differential term (amount of change in damping force adjustment standard value APg during dT) Then, write the damping force adjustment standard value APg read this time to register APGP (63) , this register APGP
The data written to is used for the first time (after dT) in the calculation of APpdf when proceeding to ``calculation of rApdf'' (6).
Amount of change in damping force adjustment S quasi-value Apg (Apg - Apg
It is used as A PgP in the calculation of p).

Referring again to FIG. 3a, the CPU 60 next generates a damping force adjustment amount Ardf corresponding to the absolute lateral acceleration value Rg, that is, a damping force adjustment amount Ardf appropriate for suppressing the lateral tilt of the vehicle body caused by Rg. Calculate (7).

The contents of "rArdf calculation" (7) are shown in FIG. 3d.

The memory area (Table 3) in the ROM 62 contains standard value data (A
rg) has been written, the CPU 60 is associated with it by the horizontal acceleration absolute value Rg (contents of register RG). lJ! The 1-minute standard value data Arg is designated and this individual data Arg is read from the table 3 of the ROM 62 (71).

Then, the damping force correction integral Ardf for suppressing the lateral tilt caused by Rg (absolute value of lateral acceleration) is calculated as follows (72).

Ardf= Krl (Kr2 ・Arg+ Kr3
(Arg-Argp)) Krl: Coefficient value that determines the contribution ratio (distribution ratio) with other damping force adjustments Kr2: Coefficient Kr of the proportional term of PI (proportional/derivative) control
3: Coefficient Argp of differential term of PI (proportional/derivative) control
: Before dT, the damping force adjustment standard value data Arz (register ARG) read from Table 3 corresponding to Rg.
Contents of P) (Arg - Argp): Differential term (change in damping force adjustment standard value Arg during dT) Then, sign the damping force adjustment standard value Ar (5) read this time into register ARGP ( 73), this register ARG
The data written to P is the fifth time (rArdf after dT).
When proceeding to "Calculation" (7), in the calculation of Ardf, the amount of change (A rg - A
rgp) in the calculation of A rgp).

Referring again to FIG. 3a, CPU 60 then:

The damping force adjustment amount E rdf , A calculated as described above
pdf and A rdf are added, and the obtained sum is multiplied by a coefficient (weighting coefficient) Kc that determines the contribution ratio between the target damping force and the damping force adjustment for suppressing the upward vibration of the wheel section, which will be described later. Calculate the primary target damping force ATdf (8)
, A Tdf= Kc・(Erdf+ Apdf+
Ardf).

The CPU 60 then outputs the manual (potentiometer 81) input given to the main controller 70:J.
R! I [A adf (damping force corresponding to the content Aa of register AA, W!1 value) is the primary target damping force ATdf
is added to calculate the secondary target damping force ATdfo (9
). A Tdf o = A Tdf + Aadf.

Next, the CPU 60 determines the signal level (A+*
) to determine whether the switch 83 is open (L: stop of damping force control is specified) or closed (H: execution of damping force control is specified) (IO).

When the switch 83 is closed (■), the secondary target damping force ATdfo is written to the output register Rout (1
1) When the switch 83 is open (L), the secondary target damping force ATdf is the standard high damping value (fixed value) AT
Check whether it is greater than or equal to s- (14).

If so, the secondary target damping force ATdfo is written to the output register RouL (11), but ATdfo is ATs
When it is less than m, the output register Rout is set to AT
Write sm (15). That is, when damping force control stop is instructed (Aa+=L).

The secondary target damping force ATdfo calculated as described above for damping force control and the standard high damping value (fixed value) ATsm,
Write the larger one to the output register Rout.

The contents of this output register Rout are the tertiary target damping force, which is calculated by the main controller 70. The final target damping force data is set in the latches of data output circuits 71 to 74. That is, the CPU 60 gives the data of the output register Rout to the data output circuits 71 to 74, and instructs each of the circuits 71 to 74 to read (latch) the data sequentially (12).

The CPU 60 next waits for the timer dT to time out (13), and when the time has expired, returns to step 3 to start the timer dT, and then executes the step 3 described above.
Execute the following to read the outputs of the sensors 55 to 58, 81.83, calculate the target damping force, and use the data output circuit 71.
~74 is updated and output. In this way, the CPU 60
dT same cycle, reading output of sensors, etc., updating target damping force 't'iJ, 'H, and data output circuit 71
Repeat steps 74 to 74 to update the target damping force data.

FIG. 4a shows the control operation of the CPU 3O of the sub-controller 51. When the power is turned on, the CPU 40 outputs, to the output port to the output interface 48, the level (ff1 level (r-: non-energized)) that should be output during standby, and the internal register and timer.

Set the counter etc. to the content that should be set during standby.

Inhibition of internal interrupt 1 and internal interrupt 2, which will be described later, is set (22).

Next, the CPU 40 stores data Ts indicating one cycle Ts of duty control in the off period register TD used for controlling the energization duty of the electric coil 38 of the shock absorber 1.
is written (23), a timer TD that takes a TD time limit ('ro is the contents of register TD) is started (24), and internal interrupt 1 is enabled (25).

Note that the energization duty control for the electric coil 38 is performed by the fourth
As shown in figure a, Td(Td
≦Ts), the electric coil 38 is de-energized and the primary (Ts
-Td), the electric coil 38 is energized, and this is repeated at the same period Ts, and the contents of the register TD are the second Td.
d.

Therefore, internal interrupt 1 (Figure 4C) is triggered by timer TD.
It is activated by the time-out of the electric coil 38.
Instead, start a timer (Ts-TD) with a time limit of (Ts-Td) to enable internal interrupt 2. Internal interrupt 2 (Figure 4d)
-TD), and this internal interrupt 2 switches the electric coil 38 from on (energized) to off (de-energized) and starts timer TD.

By executing these internal interrupts 1 and 2, the electric coil 3
At 8.

The current is supplied with a duty of 100% (CTs-TD)/TsX. TD is register TD
(= Td: non-current period Td shown in Figure 4a)
It is.

At initialization (22), the contents of flag register ENF are set to 0.
(designates continuous OFF of the electric coil 38), Ts is written in the register TD in step 23, and the energization duty is designated as 0% (continuous OFF), so the timer TD is started (24 ), and in the state (25) where internal interrupt 1 is enabled, when timer TD times out, the CPU 40 issues internal interrupt 1 (IN
Proceed to T1) and in steps 36-37-38-39,
Coil driver 49 via output interface 48
, give L that specifies turning off the electric coil 38 (37)
, disable internal interrupt 238), restart timer TD39), and when timer TD times out, similar interrupt processing is executed again, so coil driver 4
9 is continuously instructed to turn off (L), and the electric coil 49
is not energized. That is, the shock absorber 1 is set to the maximum damping force.

Now, after completing step 25, the CPU 40 determines the sampling period (=
Start a timer dt with a dt time limit (2
6) Convert the absolute value of acceleration Vg of the vertical vibration of the front right car visor into digital data and write it to the register VC, and read the data (Rout) held in the data output circuit 71 and put 1 into the register ROUT (27) . Note that when the CPU 60 updates and latches the data in the router register Rout to the data output circuit 71, the decoder 59 provides the data output circuit 71 with a signal specifying data capture (latching), and this signal is used as a busy signal to output the data to the data output circuit. 71 to the CPU 40, when this busy signal is present, the CPU 40 suspends reading of data Rout and waits for the busy signal to disappear (change from busy level to ready level) in order to avoid reading error data. and read the data Rout.

Next, the CPU 40 calculates a damping force Avdf that suppresses the vertical vibration of the front right wheel portion of the vehicle body based on the acceleration absolute value Vg of the vertical vibration of the front right wheel portion (28).

FIG. 4b shows the contents of rAvdf calculation J (28).

The damping force adjustment standard value data (Avg) corresponding to the absolute acceleration value Vg of vertical vibration is written in the memory area (Table 4) in the ROM 45.

The CPU 40 specifies the adjustment standard value data Avg associated with the vertical vibration acceleration absolute value Vg (contents of the register VG), and then R-values this individual data Avg.
It is read from table 4 of the OM45 (281), and is generated by Vg (absolute value of acceleration in the vertical direction). A damping force target value Avdf for suppressing vehicle body vibration of the front right wheel portion is calculated as follows (282).

Avdf= KVI ・(Kv2 ・Avg+ Kv3
(Avg −Av(Hp)) Kyl: Target damping force (R
Coefficient value (weighting coefficient value) that determines the contribution ratio (distribution ratio) with
3: Coefficient Avgp of the differential term of PI (proportional/differential) control
: Before dt, damping force adjustment all standard value data AvlH (register AV
Contents of GP) (Avg - Avgp): Differential term (amount of change in the damping force adjustment S quasi-value Avg during dt) Then, write the damping force adjustment standard value Av6 read this time to the register AVGP (283 ). This register AVG
The data written to P will be stored as “Av” next time (dtffl).
In calculating Avdf when proceeding to df calculation J (28), damping force; *U amount of change in standard value Avg (Avg
−Avgp) is used as A vgp.

Referring again to Figure 4a. Next, the CPU 40 calculates the damping force ATd1 to be set in the shock absorber 1 as follows (29).

A Td 1 =Rou7−AvdfIn addition, Rou
t is the content of the register ROUT (damping force target value received from the data output circuit 7I (output register Rou of the CPU 60)
content of t).

Next, the CPU 40 calculates the calculated damping force ATd.

It is converted into a current value (energization duty of the electric coil 38: more precisely, the off period Td between the duty control period Ts) (30). In this, R
Duty data (off period data) Td that provides the required damping force in a certain memory area (Table 5) of OM45
is written, the CPU 40 specifies the off-period data Td associated with the calculated damping force ATd, and reads this individual data Td from the table 5 of the ROM 45.

Next, the CPU 40 stores the read data Td in the register T.
D is written (31), and it is checked whether the data Td (=content TD of register TD) is longer than one period Ts of the energization duty control (32).

If it is greater than or equal to Ts, this means that the electric coil 38 is turned off continuously, so to indicate this, O is written in the flag register ENF (34; same a) to clear the register ENF, and the data Td is less than Ts, the electric coil 38 is turned on (
Since this means to turn off (energize) and off (de-energize), 1 is written in the flag register ENF to indicate this (33).

Next, the CPU 40 waits for the timer dt to time out (35), and when the timer dt times out.

Return to step 26 to start timer dt, and then execute step 27 and subsequent steps described above.

Read Vg and Rout, calculate the damping force ATd to be set in the shock absorber 1, convert it to off-period data Td between -periods Ts of energization duty control, and write this to the register TD. Check whether the value is greater than or equal to Ts.

If the value is above, 1 is written to the flag register ENF, and if it is less than the value, the flag register ENF is cleared.

The same applies below. In this way, the CPU 40.

The damping force (the energization duty of the electric coil 38) of the shock absorber is updated at the same cycle as dt.

When the content of the flag register ENF is O, the timer TD times out and the CPU 40 proceeds to internal interrupt 1 shown in FIG. 4C.

Execute steps 36-37-38-39 to turn off the electric coil 37) and disable internal interrupt 2.
8), starts timer TD (39), so TD
(In this case T D = Td = Ts) Internal interrupt in synchronization! is executed, and the electric coil 38 is on (energized).
Not done.

The content of flag register ENF is 1 (register TD
When the content of T D = Td is less than Ts).

When the timer TD times out and the CPU 40 proceeds to internal interrupt 1 shown in FIG. 4c, the CPU 40 executes step 36-40-4.
Execute step 1-42 to turn on the electric coil 38 (energized) (40) and start the timer (Ts-TD).41
) Enable internal interrupt 2 (42).

When the timer (Ts-TD) times out, the fourth
Proceeding to internal interrupt 2 shown in Figure d, the electric coil 38 is turned off (de-energized) (43) and the timer TD is started (44).As a result, when the content of the flag register ENF is (■), (Ts- During TD), Ts-
The electric coil 38 is turned on (conducting ff1) during Td, and the electric coil 38 is turned off (de-energized) during the next Td.
The electric coil 38 is turned on (energized) during s - T d, so that - period Ts, (Ts - Td)/TsX
A current is passed through the electric coil 38 with a duty of 100%, and the damping force (ATdl) corresponding to this duty is
(by means of plunger 32).

In the above embodiment, the target damping force (ATdf) is calculated in common for all the shock absorbers 1 to 4, and is given to each individual sub-controller 51 to 54. In this process, the required adjustment amount Avdf corresponding to the acceleration of the vertical vibration of the nearest wheel of each shock absorber 1 to 4 is calculated, and the damping force (
ATdl) is calculated and the damping force of each shock absorber 1 to 4 is set to this damping force (ATdl). Depending on the polarity of acceleration (acceleration or deceleration = leaning forward or backward), polarity of lateral acceleration (turning right or turning left = leaning left or leaning right), etc. Then, calculate the load distribution and polarity (extensional load or compression load) of each of the four wheels due to these, and calculate the target damping force of each shock absorber individually according to this load distribution and polarity. These may be latched in the data input cycles t1871-74.

〔Effect of the invention〕

In any case, in the damping force control device of the present invention.

Valve means (32) for regulating the degree of communication opening between the spaces (15, 16) in which the shock absorber (1) can move substantially steplessly and generate a pressure difference due to the vertical movement of the piston (14).
The damping force can be set steplessly,
Further, the damping force control device has a detecting means (55 to 58°65
- 6B) corresponding to the detected values (Rs, Vs, RgrPg), a first calculation means ( 60); As a result, the damping force control for suppressing the change in vehicle attitude due to the force applied to the vehicle body in response to the driving condition, which is the same as before, can be performed more precisely than before by controlling the target damping force (ATdf). In other words, it can be realized more precisely and smoothly than in the past by calculating the value and setting it in the shock absorber.

The damping force control device of the present invention further includes vibration detection means (41, 39) for detecting vertical vibration of the vehicle body;
41, 39) for calculating a damping force reduction amount (Avdf) for suppressing the vertical vibration of the vehicle body;
the valve means (32) to a position corresponding to a value (ATdl) obtained by subtracting the damping force reduction amount (Avdf) from Tdf);
valve drive control means (40) for instructing the urging means (49) to drive the valve drive control means (40), which controls the damping force to suppress changes in the posture of the vehicle due to forces applied to the vehicle body in accordance with driving conditions. In between, when the vibrations of the vehicle body are strong, the damping force is lowered, and conversely, when the vibrations are weak, the damping force is increased, achieving damping force control that provides the best ride comfort possible. Since the shock absorber is capable of linearly setting the damping force, the target damping force (ATdl) for suppressing changes in vehicle attitude and the amount of damping force reduction (Aνdf) for improving ride comfort are set as follows.
It is possible to calculate the damping force (ATdl) in accordance with the situation at the time, calculate the damping force (ATdl) that closely reflects both of them, and set this in the shock absorber (1). That is, it is possible to simultaneously suppress changes in vehicle posture and improve vehicle ride comfort, precisely and smoothly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 2a is an enlarged longitudinal sectional view of the shock absorber 1 shown in FIG. 1; FIG. 2b is an enlarged partial longitudinal sectional view of the shock absorber 1 shown in FIG. Figures 3a, 3b, 3c and 3d are the first
3 is a flowchart showing the control operation of the microprocessor 60 shown in the figure. Figures 4a, 4b, 4c and 4d show the first
3 is a flowchart showing the control operation of the microprocessor 40 shown in the figure. 1 to 4: Shock absorber (shock absorber) 1
0: Piston rod 11: Upper end base 12: Inner cylinder (cylinder) 13: Outer cylinder 14:
Piston (piston) 15: Upper space 16: Upper space (15
, 16: Space where a pressure difference occurs due to the vertical movement of the piston)
17: Valve device 18: Lower end base 18a: Lower end base space 19: Flow path 20
: Check valve member 21: Compression coil spring 22: Flow path 23: Check valve member 23a: Leaf spring 24: Outside space 25
: Bottomed cylinder 25a: End plate 26: Flange 27: Rod improvement space 28: Rod inner lower space 29: Flow port 30
: Hole 31: Hole 32 Ni plunger (valve means) 33. 34: Flange 35: Groove 36: Compression coil spring 37: Magnetic core 38
: Electric coil (electrical means) 38a: Coil bobbin 40 = Microprocessor (second calculation means, valve drive control means) 41 to 44: Vibration sensor (vibration detection means) 45
: ROM 46 : RAM
47: Decoder 48: Output interface 49: Coil driver (electrical energizing means) 51~
54: Sub-controller 55: Handle rotation angle sensor 56; Rotary encoder 57, 58:
Acceleration sensor 59: Decoder 60: Microprocessor (first calculation means) 61: RAM
62: ROM65-68: Signal processing interface (55-58. 65-68: Detection means for detecting the force applied to the vehicle body) 70: Main controller 71-74: Data output circuit 81: Potentiometer 82: Buffer amplifier 83: Switch 84: Puffer amplifier voice 28 figure ψ3b figure voice 3C figure 5! ! 3d diagram

Claims (1)

[Claims] A cylinder, a piston that divides an inner space of the cylinder, a rod fixed to the piston and extending outside the cylinder,
Valve means that can be moved substantially steplessly and that defines the degree of communication opening between the spaces that generates a pressure difference by the vertical movement of the piston, and an electric valve that drives the valve means and determines the degree of communication opening. a shock absorber having means; an electric energizing means for energizing the electric means; a detection means for detecting a force applied to the vehicle body that causes a change in the load applied from the vehicle body to the wheels; a detection value of the detection means; a first calculation means for calculating a target damping force that suppresses a change in the height of the vehicle body relative to the wheel due to a change in the force applied to the vehicle body; a vibration detection means for detecting vertical vibration of the wheel or the vehicle body; a second calculating means for calculating a damping force reduction amount for suppressing vertical vibration of the vehicle body in response to a detected value of the means; and a value corresponding to a value obtained by subtracting the damping force reduction amount from the target damping force. A damping force control device for a suspension, comprising: valve drive control means for instructing the urging means to drive the valve means to the position.