JP2630270B2 - Damping force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force control device for controlling the damping force characteristic of a shock absorber of a vehicle via an actuator, and more particularly, to assure the normal operation of the actuator at all times during execution of the damping force control. It relates to the technology to be performed.

[0002]

2. Description of the Related Art In general, the above-mentioned damping force control device includes (a) a shock absorber in a suspension device for connecting a sprung member and a unsprung member of a vehicle to each other in response to a periodic drive signal supplied from the outside. An actuator for changing the damping force characteristic, and (b) damping force control means for controlling the damping force characteristic of the shock absorber by supplying a drive signal to the actuator and controlling the driving signal are provided.

A conventional example of this kind of damping force control device is disclosed in Japanese Utility Model Laid-Open Publication No. 63-3536, which changes damping force characteristics according to the temperature of hydraulic oil in a shock absorber. Accordingly, the damping force control device can achieve the damping force characteristic as desired irrespective of the change in the temperature of the working oil, that is, the change in the viscosity of the working oil.

[0004]

In this type of damping force control apparatus, conventionally, a drive signal is always supplied to the actuator at the same cycle, so that the damping force characteristic of the actuator is controlled. However, if the drive signal is always supplied at the same cycle to operate the actuator during execution of the damping force control, the actuator may not operate properly at the start of the damping force control. For example, at the start of damping force control, the sliding surface inside the shock absorber is not sufficiently familiar (due to running out of oil, etc.)
For this reason, at the start of the damping force control, the driving load over which the driving force and torque of the actuator must overcome each other increases, and the actuator may not operate as expected. As a result, for example, when the actuator is a step motor, so-called step-out may occur.

[0005] Therefore, the present invention is, by driving the stepper chromatography data as an actuator in advance prior to the damping force control, the step motor from the start of the damping force control
It is intended to ensure that the data operates properly .

[0006]

The object is achieved according to the present invention.
Equipped with an ignition switch operated by the driver
The sprung member and the unsprung member
Connected to each other by suspension device with bushover
Of the shock absorber
(A) An externally supplied damping force control device
Of the shock absorber in response to a periodic drive signal
A step motor that changes the damping force characteristics;
Supply the drive signal to the stepping motor and control it
Control the damping force characteristics of the shock absorber.
(C) the ignition switch.
To detect that the driver has been turned on by the driver.
Ignition switch operation detecting means, and (d) the ignition switch
The operation switch has been turned on by the driver.
Is detected by the ignition switch operation detecting means.
And the damping force is controlled by the damping force control means.
Prior to the first execution of control, the damping force control means
The drive signal has a longer period than the period supplied during the execution of the control.
Signal to the stepper motor.
Pre-driving means for driving the stepper motor.
And is solved by.

Here, the term "ignition switch" is often used.
To start the vehicle's engine, as is known
To be turned on by the driver and stopped
The switch is operated to be in the OFF state.

[0008] One embodiment of the present invention is the above shock absorber.
The sawer connects its upper and lower cylinders to each other.
The effective passage area of the passage connected to the
The damping force characteristic is changed by
And the valve device is driven by the step motor.
A fully open position to fully open the passage and a fully closed position to fully close the passage;
Having a valve actuated between
Drive means sets the valve between a fully open position and a fully closed position
Wherein said driving signal for the number operated stearyl Ppumo
This is an aspect in which it is supplied to the

[0009]

In the damping force control device according to the present invention , the driver operates the ignition switch of the vehicle by the pre-driving means.
Switch is turned on and the damping force control
Prior to the first execution of damping force control by the step,
Data is driven. The stepping motor is driven in advance, thereby reducing the driving load of the stepping motor at the start of the damping force control, for example, because the sliding surface in the shock absorber is achieved. . Also, the previous drive of such a stepping motor, proper period to the step motor, that is performed by supplying a driving signal with period longer than that of the drive signal in the damping force control. This is because a larger driving force / torque in the damping force control can be generated, and the pre-driving is reliably performed.

[0010]

Therefore, according to the present invention, the driving load of the step motor is reduced prior to the damping force control, and thus, the normal operation of the step motor is guaranteed from the beginning of the damping force control.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described in detail. This embodiment is a damping force control device for a four-wheel vehicle. As shown in FIG. 1, the damping force control device is a suspension device for connecting a sprung member and a unsprung member of a vehicle based on at least a vertical acceleration α of a sprung member of the vehicle (hereinafter referred to as a sprung acceleration). It controls the damping force characteristics of the shock absorber.

As is well known, the shock absorber is constructed by slidably fitting a piston to a cylinder. The oil chamber in the cylinder is partitioned by the piston into an upper cylinder chamber and a lower cylinder chamber, and the flow of hydraulic oil between these two chambers is permitted by a narrow passage formed in the piston or the like. A rod extends concentrically from the piston. FIG. 2 shows only the piston 20 and the rod 22 in a sectional view. In the present embodiment, the damping force f and the relative speed v are changed by changing the effective flow area of the illustrated passage 26 by the valve device.
_The damping force characteristic, which is the relationship with _S , is changed. Here, the “relative speed v _S ” means the change speed of the relative displacement δ _S between the sprung member and the unsprung member in the vehicle vertical direction. The valve device is actuated by the movement of the stepper motor being transmitted via a movement transmission mechanism. In this embodiment, the valve device, the motion transmitting mechanism, and the step motor are all housed in the space inside the rod 22.

An example of the valve device is the illustrated spool valve device 30.
It is. The spool valve device 30 is disposed in the middle of the passage 26 and has a rod 22 functioning as a housing.
The spool 32 is slidably fitted to a part of the. The spool 32, depending on its axial position,
The passage area of the passage 26 is changed.

FIG . 1 shows a step motor 40.
You. The step motor 40 includes a rotor 42 and a stator 44
, And a permanent magnet 46 is fixed to the rotor 42, and an electromagnet 48 is fixed to the starter 44. The step motor 40 is of a wet type, and a rotor chamber, which is a cylindrical space between the stator 40 and the rotor 42, passes through a gap between a screw member 54 and a housing of the rod 22, which will be described later, and the like. Is in communication with
An example of the motion transmitting mechanism is a motion converting mechanism that converts the rotational motion of the step motor 40 into a linear motion of the spool 32. An example of the motion converting mechanism is the illustrated ball screw mechanism 5 shown in FIG.
0. The ball screw mechanism 50 includes a female screw member 52 that rotates with the rotor 42, a male screw member 54 screwed to the female screw member 52 via a plurality of balls, and an axially slidable state of the male screw member 54 while preventing rotation. And a supporting member 56 for supporting, and configured to convert the rotational movement of the female screw member 52 into a linear movement of the male screw member 54.

The step motor 40 is, as shown in FIG.
Connected to the controller 60,
Thus, the damping force characteristic of the shock absorber is controlled via the step motor 40. The controller 60 is a CP
The computer mainly includes a U70, a ROM 72, and a RAM 74. The output side of the computer is connected to a step motor 40, and the input side is connected to a sprung acceleration sensor 80, a relative displacement sensor 82, and a vehicle speed sensor 84. . The sprung acceleration sensor 80 is provided on a sprung member for each wheel and detects the sprung acceleration α of the sprung member. The relative displacement sensor 82 detects the relative displacement δ _S of each sprung member in association with the sprung member and the unsprung member for each wheel. Each relative displacement sensor 82
Also through each differentiation circuit 86 is connected to the input side, after all, the differential value of the relative displacement [delta] _S, ie relative velocity v
_{S is} also detected. The vehicle speed sensor 84
It detects the running speed V of the vehicle. controller
At the input of 60 further start the engine of the vehicle
To be turned on by the driver to stop
Switch 88 which is operated to be turned off
Is also connected.

The configurations of the ROM 72 and the RAM 74 are conceptually shown in FIGS. 3 and 4, respectively. In the ROM 72,
As shown in FIG. 3, various programs including a low temperature determination routine (see FIG. 5) and a damping force control routine (see FIG. 6) are stored in advance. The ROM 72 also has
Various maps are also stored. On the other hand, in the RAM 74,
As shown in FIG. 4, a memory or the like for storing data supplied from various sensors is provided. An actual sprung acceleration memory, a relative displacement memory, a relative speed memory, a vehicle speed memory, and the like are provided. The RAM 74 is also provided with a memory for storing various flags. The controller 60 controls the damping force characteristics of the shock absorber via the step motor 40 for each wheel by the CPU 70 executing the program in the ROM 72 while using the RAM 74.

When the operating oil of the shock absorber is at a low temperature (for example, about −20 to −10 ° C. or less), the driving oil has a high viscosity, so that even if a drive signal is supplied to the step motor 40 (the ), The rotor 42 cannot rotate to overcome the resistance of the hydraulic oil, and there is a possibility that the step-out occurs. If the viscosity of the hydraulic oil interposed between the spool 32 and the rod 22 is high, the movement resistance of the spool 32 with respect to the rod 22 increases, and the rotational load of the step motor 40 increases. This is because if the viscosity of the hydraulic oil is high, the rotational resistance of the rotor 42 to the stator 44 increases, and the rotational load of the step motor 40 increases. Accordingly, in this embodiment, the low
Whether or not the oil temperature is low is determined by the temperature determination routine, and when it is determined that the oil temperature is low, the supply of the drive signal to the step motor 40, that is, the damping force control is performed by the damping force control routine. It is forbidden.

The determination of the oil temperature is performed utilizing the following facts. Generally, the oil temperature is low only at the beginning when the ignition switch of the vehicle is turned on, that is, immediately after the start of each run. A certain relationship is established between the oil temperature, the relative speed v _S and the damping force f. That is, the damping force f increases as the relative speed v _S increases, and the damping force f increases as the oil temperature decreases. Constant relationship between the sprung acceleration α and the damping force f and relative displacement [delta] _S is satisfied. That is, the motion system composed of the sprung member, the suspension device, and the unsprung member can be modeled as shown in FIG. 7. In this model, the motion of the sprung member is described by the following equation. Because it can be. mα = − (cv _S + kδ _S ) = − (f + kδ _S ) where m: mass of a sprung member of a 1/4 vehicle (fixed value) c: damping coefficient of shock absorber k: spring constant of suspension spring (fixed value) )

The oil temperature is determined by utilizing these facts. In this embodiment, the stepping motor 40 which varies the damping force characteristic of the shock absorber and changes the area of the passage 26 is used. Is not always fixed. On the other hand, in the present embodiment, since there is no sensor for detecting the operation position of the step motor 40, the actual operation position cannot always be accurately grasped. Although it is possible to estimate the operating position from the contents of the drive signal supplied to the step motor 40, if the step motor 40 loses synchronization, the drive signal and the operating position do not correspond to each other, and the operating position Can not be grasped correctly.

Therefore, in this embodiment, immediately after the start of each run, the oil temperature determination period is set.
It is ensured that the actual operating position of the step motor 40 is at the predetermined position. Although the details will be described later, by ensuring that the home position return of the step motor 40 is performed mechanically immediately after the end of the previous run, the step motor 40 is always returned to the original position as the planned position immediately after the start of the next run. It is as it is.

Based on these circumstances, the oil temperature judgment is performed in the following manner. That is, when the oil temperature is an ideal value (for example, about 20 to 30 ° C.) (hereinafter also referred to as a high temperature), the sprung acceleration α expected to be generated in the sprung member is determined as an ideal value, When the actual value of the sprung acceleration α tends to be relatively large with respect to its ideal value, it is performed by a relative estimation method of determining that the oil temperature is low. In order to adopt this method, the ROM 72
In advance, the relationship between the relative velocity v _S and damping force f which satisfies the shock absorber when the oil temperature level is ideally stored in. An example of this relationship is shown in a graph in FIG.

Hereinafter, an outline of this method will be described with time. First, in accordance with the above relationship, the damping force f is determined from the current value of the relative velocity v _S. Oil temperature height is the damping force f expected to occur to the shock absorber is determined as an ideal damping force f _R when it is assumed to be ideal. Then, based on the current value of the ideal damping force f _R and the relative displacement [delta] _S, by utilizing the equation of motion, occurs sprung when the oil temperature level is assumed to be ideal Then, the expected sprung acceleration α is calculated as the ideal sprung acceleration α _R. Then, the actual sprung acceleration α _A
Is more likely to be greater than the ideal sprung acceleration α _R. In spite of the fact that the spool 32 is in the original position, the oil temperature is low, so that a larger damping force f is actually generated than expected, and as a result, whether the actual sprung acceleration α _A is larger than expected. Is determined.

The above-described oil temperature determination is performed by a low-temperature determination routine. Hereinafter, the details of the low-temperature determination routine will be specifically described with reference to FIG. This routine, controller
The ignition switch 88 is turned on by the roller 60
As soon as the operation is detected, execution is started. First, Step S11 (hereinafter, simply the same for that. Other step S11) in the initial setting is performed, a counter CNT, which will be described later, the measurement time t _M and low temperature flag, respectively, are 0,0 and 1. Next, in S12, the actual sprung acceleration α is obtained from various sensors.
_A , the relative displacement δ _S and the relative velocity v _S are read, and R
Stored in AM74. Subsequently, in S13, RO
By using the v _S -f map stored in the M72, the ideal damping force corresponding to the current value of the relative velocity v _S f _R
Is determined. Thereafter, in S14, the ideal damping force f
Based on the respective current value of _R and the relative displacement [delta] _S, the current value of the ideal sprung acceleration alpha _R in accordance with the motion equation is calculated.

Subsequently, in S15 to S21, it is determined whether or not the actual value of the sprung acceleration α tends to be relatively large with respect to the ideal value. That is, these S15-2
1 is a group of steps for comparing the actual value and the ideal value of the sprung acceleration α. Both the actual sprung acceleration α _A and the ideal sprung acceleration α _R take not only positive values but also negative values, and vibrate finely. Therefore, a simple comparison between the two cannot always be performed correctly, due to errors in the actual sprung acceleration α _A and errors in the ideal sprung acceleration α _R. Therefore, in the present embodiment, the absolute value processing is performed on the actual sprung acceleration α _A and the ideal sprung acceleration α _R, and then the low-pass filter processing, which is an example of the smoothing processing, is performed on the absolute values. Is performed, and a low-temperature determination is performed based on the comparison result between the values after the smoothing. For example, regarding the raw signals of the actual sprung acceleration α _A and the ideal sprung acceleration α _R represented by the solid line graph in FIG.
Absolute value signals | α _A | and | α _R | represented by broken-line graphs are generated, and then smoothed value signals | α _A | represented by alternate long and short dash lines.
_LP , | α _R | _LP is generated, and eventually the raw sprung acceleration α
Is converted to a value on a line that smoothly connects the absolute value peak points along the time axis, and the converted values are compared with each other to determine the oil temperature.

If the actual sprung acceleration α _A after smoothing becomes larger than the ideal sprung acceleration α _R even once, it is immediately determined that the actual sprung acceleration α _A is more likely to be larger than the ideal sprung acceleration α _R. Is possible. However, even though the values after smoothing are compared with each other, the final determination based on only one comparison result may lack reliability. Therefore, in the present embodiment, the number of times that the difference between the actual sprung acceleration α _A and the ideal sprung acceleration α _R becomes larger than the positive reference value A during the elapse of the determination period T _M is determined by the counter C
NT is obtained as the value of NT, and when the value becomes larger than the positive reference value N, it is determined that the actual sprung acceleration α _A and the ideal sprung acceleration α _R tend to be significantly different, and the oil temperature is low. Is determined. Moreover, the possibility that the oil temperature is low is high again next time, so that the comparison between the actual sprung acceleration α _A and the ideal sprung acceleration α _R is resumed. On the other hand, if the final value of the counter CNT in the determination cycle T _M is not larger than the reference value N, it is determined that the oil temperature is high, and the execution of this routine ends, and thereafter, the ignition switch 88 is turned off. After that, the execution is stopped until it is again turned on. This is because, in the present embodiment, it is assumed that the oil temperature does not decrease after the oil temperature has increased.

The above contents will be described in detail.
In S15, absolute value processing is performed on the actual sprung acceleration α _A and the ideal sprung acceleration α _R to obtain absolute values | α _A | and | α _R |. Next, S16
, Low-pass filtering is performed on the absolute values | α _A | and | α _R |. For example, for the absolute value | α _A |, the smoothed value | α _A | _LP is calculated using the equation | α _A | _LP = a · | α _A | + (1−a) · | α _A | _LP On the other hand,
Similarly, for the absolute value | α _R |, the smoothed value | α _R | _LP is calculated using the equation | α _R | _LP = a · | α _R | + (1−a) · | α _R | _LP. Is done. In these equations, | α _A | _LP and | α _R |
_LP represents the previous smoothed value, respectively.

Thereafter, in S17, the smoothed value | α _A
| Smoothed value from _LP | alpha _R | value or not greater than the reference value A by subtracting the _LP is determined. If it is larger, the determination is YES
In S18, the value of the counter CNT is increased by 1, but if it is not large, the determination is NO and S18 is skipped. In any case, S1
At 9, the measurement time t _M is increased by a certain increment Δt _M , and thereafter, at S20, it is determined whether the current value of the measurement time t _M has become equal to or longer than the determination period T _M. Otherwise, the determination is NO and the process returns to S12, but if so, the determination is YES, and in S21, it is determined whether the final value of the counter CNT is larger than the reference value N. If it is larger, the determination is YES, it is determined that the oil temperature is low, and in S22, the counter CNT
After the value of the measurement time t _M is initialized to 0, the process returns to S12. The actual sprung acceleration α _A and the ideal sprung acceleration α _R are compared again. On the other hand, when the final value of the counter CNT is not larger than the reference value N, the determination in S21 is NO, it is determined that the oil temperature is not low, the process proceeds to S23, and the low temperature flag is set to 0. Thus, the execution of this routine ends, and the execution is stopped until the current traveling ends. This routine is executed for each wheel.
Stored in M74.

In this embodiment, the mass m of the sprung member in the equation of motion is a fixed value. This is because the relationship between the actual value and the ideal value of the sprung acceleration α is determined by the weight of the vehicle weight. This is because it has been experimentally confirmed that it is hardly affected by the fluctuation.

In this embodiment, the expected position of the step motor 40 is the original position of the
2 is set to the operating position corresponding to the axial position where the passage 26 is fully opened. The position where the damping force characteristic is the softest characteristic, that is, the position where the amount of the hydraulic oil flowing through the passage 26 is the largest is set.
The influence of the viscosity of the hydraulic oil appears strongly in the difference between the actual value and the ideal value of the sprung acceleration α, and the accuracy of determining the oil temperature is improved.

On the other hand, the damping force control routine, in which at least the actual sprung acceleration alpha _A as input, performs a damping force control for automatically controlling the damping force characteristics of the shock absorber. For example, damping force control may be performed based on the skyhook theory.

In the damping force control routine, when it is determined that the oil temperature is low, the damping force control is not performed. If a drive signal is supplied to the step motor 40 even though the oil temperature is low, the step motor 40 may lose synchronism, and the damping force characteristics may not be controlled as expected. However, even if it is determined that the oil temperature is not low, the vehicle speed V
Is zero, the damping force control is not performed, and the home position return of the step motor 40 is performed instead. This is because the low-temperature determination routine is designed to be executed on the premise that the step motor 40 is at the original position immediately after the start of each run, and if the home return is performed immediately after the end of the previous run, the next time This is based on the fact that the vehicle is always at the original position immediately after the start of traveling and the vehicle speed V is always 0 immediately after the traveling is completed. That is, the determination as to whether or not the vehicle speed V is 0 in this routine is one mode of determination as to whether or not the traveling is completed.

A stopper is provided on each of the rotating members such as the rotor 42 of the stepping motor 40 and the fixed members such as the stator 44. These stoppers come into contact with each other when the rotor 42 is at the original position.
2 is prevented from rotating in a direction to increase the opening of the spool 32. When returning to the origin, the rotor 42
In any rotational position, the stepping motor 40 is supplied with a drive signal that causes the stopper to abut the stopper of the stator 44 without fail.

If it is determined that the oil temperature is not low and that the vehicle speed V is not 0, the damping force control may be started immediately. However, if the damping force control is started immediately because it is determined that the oil temperature is not low, there is a possibility that the stepping motor 40 may lose synchronism. Even if the sliding surface of the spool 32 is not sufficiently adapted, or if the oil temperature of the cylinder oil chamber of the shock absorber rises, the oil temperature of the rotor chamber of the step motor 40 does not immediately rise, and the rotational resistance of the rotor 42 decreases. For example, the stepping motor 40 is initially set at the beginning of the damping force control.
Is increased, and the oil temperature in the cylinder oil chamber is high, but there is no possibility of loss of synchronism.
Therefore, in this embodiment, after it is determined that the oil temperature is not low, the stepping motor 4 is controlled prior to the damping force control.
The pre-driving operation in which 0 is operated a plurality of times is performed.

Hereinafter, the damping force control routine will be specifically described with reference to FIG. This routine is executed by the controller 6
0 turns the ignition switch 88 to the ON state.
As soon as it is detected that
Until it is detected that is operated in FF state, execution continues.

First, in S171, an initial flag described later is initialized to 1. Next, in S172, R
The low temperature flag is read from the AM 74, and in S173, it is determined whether or not this is 1, that is, whether or not it is determined that the oil temperature is low. If 1 then S
Returning to 172, the damping force control is prohibited. On the other hand, if it is not 1, the vehicle speed V is read from the vehicle speed sensor 84 in S174, and it is determined in S175 whether or not the vehicle speed V is 0. If it is 0, the origin return of the step motor 40 is performed in S176, and thereafter, the process returns to S172. On the other hand, if it is not 0, it is determined in S177 whether or not the initial flag is 1. In the damping force control executed first after the ignition switch 88 is turned on, it is determined whether or not the execution of S180 described later is the first time. This time the initial flag is 1
Therefore, the determination is YES, and the process shifts to S178.

In step S178, the step motor 40 is pre-driven. That is, prior to the damping force control, a drive signal for the reciprocating movement of the spool 32 a plurality of times is supplied to the step motor 40, and the supply of the drive signal is performed at a cycle longer than the original cycle. The reciprocating motion of the spool 32 a plurality of times is performed by first moving the spool 32 from the fully open position to the fully closed position of the passage 26 in the shock absorber, and then moving the spool 32 from the fully closed position to the fully open position as one reciprocating motion. This is realized by performing the operation continuously plural times. As a result, the sliding surface of the spool 32 is sufficiently adjusted, and the flow of hydraulic oil is generated between the rotor chamber of the step motor 40 and the cylinder oil chamber, so that the oil temperature of the rotor chamber rises. For this reason, the rotational load torque of the step motor 40 is reduced.

Thereafter, in S179, the initial flag is set to 0, and subsequently, in S180, damping force control is executed. Since the damping force control is started after the rotational load torque of the step motor 40 is reduced, the normal operation of the step motor 40 is guaranteed from the beginning of the damping force control. After that, the process returns to S172.

In this embodiment, the low-temperature flag is provided for each wheel, and the damping force control is appropriately prohibited for each wheel. However, the low-temperature flag is set to 1 for any one of the wheels. Therefore, the damping force control is uniformly prohibited for all the wheels, or the average value between all the wheels is obtained for the actual sprung acceleration α _A and the ideal sprung acceleration α _R, and the total value is obtained from the relationship between the two. The damping force control may be uniformly prohibited for the wheels.

As is apparent from the above description, in this embodiment, the ignition switch
The part that detects that the switch 88 has been turned on is
"Ignition switch operation detecting means" in the present invention
The routine of FIG. 5 and the steps S172 to S172 of FIG.
Portions for performing the 176 and S180 are "damping force control hand
Steps S171 and S177 to S177 in FIG.
The part that executes S179 is an example of the “advance driving unit”.
It is.

An embodiment of the present invention will now be described with reference to the drawings.
Although described in detail, the present invention can be implemented in other aspects. For example, in the above embodiment, the step mode
Although the damper is of a wet type built in the rod of the shock absorber, it is a matter of course that a dry type may be provided outside the rod and linked to the rod via a control rod. When the stepping motor is dry, as in the case of the wet type, the driving load of the stepping motor increases at the beginning of the damping force control due to insufficient adaptation of the sliding surface in the shock absorber.
In the case of the dry type, when the driving load of the stepping motor increases due to a seal member (for example, an O-ring or the like) interposed between the control rod and the rod of the shock absorber being fixed to the sliding surface. There is also. Besides, without departing from the scope of the claims, various modifications based on the knowledge of those skilled in the art, the present onset at aspects mutatis improved
The invention is feasible.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an electrical configuration of a damping force control device according to an embodiment of the present invention .

FIG. 2 is a partial longitudinal sectional view of a piston and a rod in a shock absorber that is one component of the damping force control device.

FIG. 3 is a diagram conceptually showing a configuration of a ROM 72 in FIG.

FIG. 4 is a diagram conceptually showing a configuration of a RAM 74 in FIG.

FIG. 5 is a flowchart showing a low temperature determination routine in FIG. 3;

FIG. 6 is a flowchart showing a damping force control routine in FIG.

FIG. 7 is a diagram showing a vibration model of the suspension device.

8 is a graph showing a relationship between a relative speed v _S stored in a ROM 72 in FIG. 3 and an ideal value of a damping force f.

FIG. 9 is a graph for explaining signal processing in a low temperature determination routine of FIG. 5;

[Explanation of symbols]

40 Step motor 60 Controller 88 Ignition switch

Claims (2)

(57) [Claims] An ignition switch operated by a driver.
The sprung member and the unsprung member are
Suspension system with shock absorber
Installed on the vehicle connected to the
A damping force control device for controlling a damping force characteristic, wherein said shock control device responds to a periodic drive signal supplied from outside.
Step mode that changes the damping force characteristics of the shock absorber
The drive signal is supplied to the
Control the damping force of the shock absorber.
Damping force control means for controlling the driving force, and the ignition switch being turned on by the driver.
Ignition switch operation detection to detect that it was made
Means and the ignition switch is turned on by the driver.
The ignition switch operation detecting means
After being detected by the damping force control means.
Before the first execution of damping force control, damping force control means
With a cycle longer than the cycle supplied during execution of the damping force control
By supplying the drive signal to the step motor
Damping force control device which comprises a pre-driver for driving a step motor I. 2. The method according to claim 1, wherein said shock absorber comprises a syringe.
Effective flow in the passage connecting the upper chamber and the lower cylinder to each other
The road area is changed by the valve device to
The damping force characteristic is changed, and the valve device
Causes the passage to be fully opened by the step motor
Operated between fully open position and fully closed position to fully close
Having a valve, wherein the pre-driving means controls the valve
Between the fully open position and the fully closed position
Means for supplying the drive signal to the step motor.
The damping force control device according to claim 1.