JPH07172127A - Vehicle suspension - Google Patents

Abstract

(57) [Abstract] [Purpose] A vehicle suspension system capable of eliminating the phase delay on the high frequency side due to signal processing for obtaining a signal having frequency dependence in the control on the rear wheel side and improving the riding comfort of the vehicle. Offer. A front wheel vertical movement detecting means c for detecting a vertical movement of a front wheel side of a vehicle body, a rear wheel vertical movement detecting means d for detecting a vertical movement of a predetermined front position of a rear wheel of a vehicle body, and a rear side A signal processing circuit e for forming a processing signal having frequency dependency from a vertical behavior signal at a predetermined front position from the rear wheel obtained by the wheel side vertical behavior detection means d, and a front wheel side vertical behavior detection means c. By the control signal formed based on the processing signal by the front wheel control unit f that performs the damping force characteristic control of the front wheel side shock absorber b ₁ by the control signal based on the obtained vertical movement signal on the front wheel side, and the processing signal by the signal processing circuit e. Rear wheel side shock absorber b ₂
Damping force characteristic control means h having a rear wheel control unit g for performing the damping force characteristic control of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for optimally controlling the damping force characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system for controlling a damping force characteristic of a shock absorber, for example, Japanese Patent Application Laid-Open No. Hei 4-
The one described in Japanese Patent No. 1911111 is known.

This conventional vehicle suspension system includes an actuator (shock absorber) which is interposed between a vehicle body and a rear wheel and is capable of increasing or decreasing the supporting force (damping force characteristic) of the vehicle body with respect to the rear wheel, and a road surface. A vertical G sensor that detects vertical acceleration acting on the vehicle body by vibration input from the front wheels due to the unevenness, a vehicle speed sensor that detects the traveling speed of the vehicle, and control means that controls the operation of the actuator based on the output of each sensor. When the control means detects that the vertical acceleration of the vehicle body detected by the vertical G sensor exceeds a predetermined value, the road surface is given a vertical acceleration of the predetermined value or more based on the output of the vehicle speed sensor. The delay time until the rear wheel reaches the unevenness is calculated, and the signal based on the vertical acceleration is inverted after the delay time from the time when the front wheel passes through the uneven road surface. Depending on the obtained control signals were those configured to actuate the actuator.

That is, in this conventional device, even if a relatively large vibration is generated in the vehicle body when the front wheels pass through the unevenness of the road surface, when the rear wheels pass through the unevenness, the vertical acceleration of the vehicle body is referred to when the front wheels pass through the unevenness. Control is performed in such a direction as to cancel the vertical acceleration of the vehicle body, whereby vibration input can be reduced when the rear wheels pass through the unevenness as compared to when the front wheels pass through the unevenness.

[0005]

However, the above-mentioned conventional device has the following problems.

That is, in general, the vertical acceleration signal detected by the vertical G sensor is converted into a vertical velocity signal by performing integration processing with a low-pass filter or the like, and various filter processings for noise cutting or removing unnecessary components are performed. However, when signal processing (filter processing) for obtaining a signal having frequency dependence is performed in this way, the phase of the processed signal becomes the phase of the input signal as shown by the dotted line in FIG. On the other hand, on the low frequency side, it advances and on the high frequency side it lags, so especially when the phase is delayed during high frequency input,
The desired control signal cannot be obtained, which deteriorates the riding comfort of the vehicle.

The above-described conventional apparatus performs preview control in which the timing of using the control signal for controlling the rear wheels is delayed according to the vehicle speed, and does not eliminate the phase shift of the signal due to the filtering process.

The present invention has been made by paying attention to the above-mentioned conventional problems, and eliminates the phase delay on the high frequency side due to the signal processing for obtaining a signal having frequency dependence in the control on the rear wheel side. The first object is to provide a vehicle suspension device that can improve the riding comfort of the vehicle, and the second object is to provide a vehicle suspension device that can improve the riding comfort of the vehicle at any vehicle speed condition. To do.

[0009]

As shown in the claim correspondence diagram of FIG. 1, a vehicle suspension system of the present invention is interposed between a vehicle body side and each wheel side, and a damping force characteristic changing means a serves to reduce the damping force. Front wheel side shock absorber with changeable characteristics b ₁
And a rear wheel side shock absorbers b _2, a front wheel side vertical behavior detecting means c for detecting the vertical behavior of the front wheel side of the vehicle body, wheel side vertical after detecting the vertical behavior of the predetermined forward position than the rear wheel of the vehicle body A behavior detecting means d, a signal processing circuit e for forming a processing signal having frequency dependency from a vertical behavior signal at a predetermined front position from the rear wheel obtained by the rear wheel side vertical behavior detecting means d, and a front wheel Based on the processing signal by the front wheel control unit f that performs damping force characteristic control of the front wheel side shock absorber b ₁ by the control signal based on the front wheel vertical movement signal obtained by the side vertical movement detection means c, and the processing signal by the signal processing circuit e. Damping force characteristic control means h having a rear wheel control part g for controlling the damping force characteristic of the rear wheel side shock absorber b ₂ by a control signal formed by the above.

The vehicle suspension system according to a second aspect is the vehicle suspension system according to the first aspect, wherein the rear wheel side vertical movement detecting means is a vertical movement sensor provided at a predetermined front position from the rear wheel position. It has been configured means.

According to a third aspect of the present invention, there is provided a vehicle suspension system according to the first aspect, wherein the rear wheel side vertical movement detecting means is a rear wheel side vertical movement sensor provided near the rear wheel. Calculating a vertical behavior signal from a rear wheel position to a predetermined front position based on the rear wheel vertical movement signal detected by the rear wheel vertical movement sensor and the front wheel vertical movement signal detected by the front wheel vertical movement detection means And a calculation means for performing the calculation. The vehicle suspension system according to a fourth aspect is the vehicle suspension system according to the third aspect, wherein a vehicle speed sensor j for detecting the vehicle speed of the vehicle is provided, and a predetermined front position from the rear wheel position is forward in proportion to the vehicle speed. It was configured to move to.

[0012]

In the vehicle suspension system according to the first aspect of the present invention, since it is configured as described above, the front wheel vertical movement detecting means detects the vertical movement of the front wheel side, and the rear wheel vertical movement detecting means. When the vertical behavior of a predetermined front position of the rear wheel of the vehicle body is detected by, the signal processing circuit performs processing for forming a processed signal having frequency dependency from the detected front wheel side vertical behavior signal. At the same time, the damping force characteristic control means controls the damping force characteristic of the front wheel side shock absorber by the control signal based on the vertical direction behavior signal of the front wheel side in the front wheel control section, and the processing signal in the rear wheel control section. The damping force characteristic control of the rear wheel side shock absorber is performed by the control signal formed based on the above.

That is, as shown by the dotted line in FIG. 15, the phase of the processed signal processed by the signal processing circuit is advanced on the low frequency side and delayed on the high frequency side (direction delayed in proportion to the magnitude of the frequency). On the other hand, as shown by the solid line in FIG. 15, the sprung vertical acceleration signal detected on the front wheel side with respect to the phase of the sprung vertical acceleration signal (rear wheel side vertical movement signal) detected on the rear wheel side. Contrary to the above, the phase of (front wheel side vertical movement signal) advances in proportion to the magnitude of the frequency. Therefore, the vertical movement signal at a predetermined front position from the rear wheel with this phase advanced By using the control for the rear wheel side, it is possible to correct the phase delay on the rear wheel side so as to eliminate the phase delay due to signal processing, and thus it is possible to improve the deterioration of the riding comfort of the vehicle due to the phase delay. .

Further, in the vehicle suspension system according to claim 4,
As shown in (a) and (b) of FIG. 23, the amount of phase advance of the sprung vertical velocity signal (vertical behavior signal) at the front wheel position with respect to the sprung vertical velocity signal (vertical behavior signal) at the rear wheel position is shown. While the vehicle speed decreases as the vehicle speed increases, FIG.
And, as is clear from the time chart of FIG. 25 showing the phase delay state of the sprung vertical velocity signal at each sprung vertical velocity detection position shown in FIG. 24, the phase at a predetermined front position with respect to the rear wheel position In view of the fact that the amount of advance becomes larger as the vehicle goes forward (closer to the front wheel position), a configuration in which a predetermined front position from the rear wheel position is moved forward in proportion to the vehicle speed is used to achieve a phase due to a change in vehicle speed. It is possible to correct the delay correction amount in a direction that eliminates the fluctuation, and thus to improve the ride comfort of the vehicle in any vehicle speed state.

[0015]

Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) First, the structure of a vehicle suspension system according to a first embodiment of the present invention will be described.

FIG. 2 is a structural explanatory view showing the vehicle suspension system of the first embodiment, which is interposed between the vehicle body and each wheel,
4 shock absorbers SA _FL , SA _FR , SA _RL , S
A _RR ( _FL is the front wheel left side, _FR is the front wheel right side, _RL is the rear wheel left side, and _RR is the rear wheel right side. And when describing these four shock absorbers collectively, And SA is simply referred to when describing these common configurations). And
The left and right shock absorbers SA _FL and SA _FR on the front wheel side are attached to the vehicle body at the mounting position (hereinafter referred to as the front wheel position),
A pair of left and right sprung vertical acceleration sensors (hereinafter referred to as vertical G sensors) 1 _FL and 1 _FR for detecting vertical acceleration at the front wheel position are provided, and the left and right rear shock absorbers SA _RL and SA _RR The vehicle body at the mounting position (hereinafter referred to as the rear wheel position) to the vehicle body has a pair of left and right vertical G sensors 1 _RL , 1 _RR for detecting vertical acceleration at the rear wheel position.
Further, in the vicinity of the driver's seat, the sprung vertical accelerations G (G _FL , G _FR , G _RL , G) from the vertical G sensors 1 (1 _FL , 1 _FR , 1 _RL , 1 _RR ) are provided. A signal processing circuit for inputting a signal G _RR ) and outputting a drive control signal to the pulse motor 3 of each shock absorber SA, and a control unit 4 as damping force characteristic control means are provided.

The above-mentioned configuration is shown in the system block diagram of FIG. 3, in which the control unit 4 comprises an interface circuit 4a, a CPU 4b and a drive circuit 4c, and the interface circuit 4a is provided with each of the vertical G sensors 1 described above.
The sprung vertical acceleration G from (1 _FL , 1 _FR , 1 _RL , 1 _RR )
(G _FL , G _FR , G _RL , G _RR ) signals are input. In the interface circuit 4a, the signal processing circuit shown in FIG. 14 is provided for each vertical G sensor 1. That is, the LPF 1 is a low-pass filter circuit for removing noise in the high frequency range (30 Hz or higher) from the sprung vertical acceleration G signal obtained by the vertical G sensor 1. LPF2
Is a low-pass filter circuit for integrating a signal indicating the acceleration that has passed through the low-pass filter circuit LPF1 and converting it into a sprung vertical velocity. HPF is a high-pass filter with a cut-off frequency of 1.0 Hz, LPF3 is a low-pass filter with a cut-off frequency of 1.5 Hz, and a band-pass filter for obtaining a sprung vertical velocity Vn signal including a sprung resonance frequency is used for both filters. I am configuring.

Next, FIG. 4 shows each shock absorber SA.
FIG. 3 is a cross-sectional view showing the configuration of the shock absorber SA in which a cylinder 30, a piston 31 that defines the cylinder 30 into an upper chamber A and a lower chamber B, and a reservoir chamber 32 are formed on the outer periphery of the cylinder 30. An outer cylinder 33, a base 34 that defines the lower chamber B and the reservoir chamber 32, a guide member 35 that guides the sliding of the piston rod 7 having a piston 31 connected to the lower end, and an outer cylinder 33 and the vehicle body. The suspension spring 36 interposed between the bumper bar 3 and
7 and 7.

Next, FIG. 5 is an enlarged sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and each through hole is formed. A compression side damping valve 20 and an expansion side damping valve 12 that open and close 31a and 31b respectively are provided. In addition, the bound stopper 41 screwed to the tip of the piston rod 7 has a stud 3 penetrating the piston 31.
8 is screwed and fixed, and this stud 38 is
A communication hole 39 that connects the upper chamber A and the lower chamber B is formed, and further, an adjuster 40 for changing the flow passage cross-sectional area of the communication hole 39 and the fluid communication depending on the direction of fluid flow. Extension side check valve 1 that allows and blocks the flow of holes 39
7 and a pressure side check valve 22 are provided.
The adjuster 40 is rotated by the pulse motor 3 via the control rod 70 (see FIG. 4). Further, the stud 38 is formed with a first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 in order from the top.

On the other hand, in the adjuster 40, a hollow portion 19 is formed, a first horizontal hole 24 and a second horizontal hole 25 which communicate the inside and the outside are formed, and a vertical groove 23 is formed in the outer peripheral portion. There is.

Therefore, a through hole 31 is provided between the upper chamber A and the lower chamber B as a flow passage through which a fluid can flow in the extension stroke.
The inside of the extension side damping valve 12 is opened through b and the lower chamber B
To the extension side first flow path D, the second port 13, the vertical groove 23,
Via the expansion side second flow path E, which opens the outer peripheral side of the expansion side damping valve 12 to the lower chamber B via the fourth port 14, the second port 13, the vertical groove 23, and the fifth port 16. Then, the extension side check valve 17 is opened to reach the lower chamber B by way of the third side flow passage F extending to the lower chamber B and the third port 18, the second lateral hole 25, and the hollow portion 19. There are four channels, channel G. Further, as a flow path through which the fluid can flow in the pressure stroke, the pressure side first valve that opens the pressure side damping valve 20 through the through hole 31a is used.
Flow path H, hollow portion 19, first lateral hole 24, first port 21
Via the pressure side check valve 22 to the upper chamber A, and the bypass flow to the upper chamber A via the hollow portion 19, the second lateral hole 25, and the third port 18. Road G
There are three channels.

That is, the shock absorber SA is constructed so that the damping force characteristics can be changed in multiple stages on both the extension side and the compression side with the characteristics shown in FIG. 6 by rotating the adjuster 40. That is, as shown in FIG.
Area where both pressure side becomes soft (hereinafter soft area SS
Therefore, when the adjuster 40 is rotated counterclockwise, the damping force characteristics can be changed to the hard side only in the expansion side in multiple stages and the compression side is softly fixed (hereinafter, the expansion side hard area H).
Conversely, when the adjuster 40 is rotated in the clockwise direction, only the compression side can change the damping force characteristic to the hard side in multiple stages and the extension side is softly fixed (hereinafter referred to as the compression side hard area SH). ) Has become the structure.

By the way, in FIG. 7, the KK cross section, the LL cross section and the MM cross section, and the MM cross section in FIG. 8, FIG. 9, and FIG. 10, and the damping force characteristics at each position are shown in FIGS.

Next, among the control operations of the control unit 4, the control operation for obtaining the control signal V will be described with reference to the flowchart of FIG.

In step 101, the front wheel side vertical G sensor 1 _F (1 _FL , 1 _FR ) and the rear wheel side vertical G sensor 1 _R (1
_RL , 1 _RR ), front wheel side shock absorber SA _F
(SA _FL , SA _FR ) sprung vertical accelerations G _FL , G _{FR at} the mounting position (front wheel position) to the vehicle body, and mounting position of the rear wheel side shock absorber SA _R (SA _RL , SA _RR ) to the vehicle body ( _Spiral vertical acceleration G _RL , G _{RR at} rear wheel position)
To detect.

At step 102, based on the values of the sprung vertical acceleration G _{F at} the front wheel position and the sprung vertical acceleration G _R at the rear wheel position, a position forward by a predetermined length b from the rear wheel position (hereinafter, referred to as "following expression") The value of the sprung vertical acceleration G _r ′ (G _r ′ _L , G _r ′ _R ) at the front position may be calculated (see FIG. 19). G _r ′ = G _R + b / a (G _F −G _R ) In the above formula, a is a wheel base.

That is, in this embodiment, the front wheel side vertical G sensor 1 _F (1 _FL , 1 _FR ) and the rear wheel side vertical G sensor 1 _R (1
_RL , 1 _RR ) and the arithmetic circuit constitute a rear wheel side vertical movement detecting means in the claims.

In step 103, the sprung vertical acceleration G
_FL , G _FR , G _r ' _L , G _r ' _R are integrated and converted into a sprung vertical velocity signal, and processed by a bandpass filter BPF, so that the sprung vertical velocity Vn (including the sprung resonance frequency is _{Vn -FL, Vn -FR, Vn '} rL, Vn' Request _rR) signal. The sprung vertical velocity Vn is given as a positive value in the upward direction and a negative value in the downward direction.

At step 104, the control signal V of each shock absorber SA is obtained based on the following equation. That is, the damping force characteristics of the rear wheel side shock absorbers SA _RL , SA _RR are _calculated from the control signal RLV, Vn ′ _rL , Vn ′ _rR , which is obtained from the input sprung vertical velocity Vn ′ _rL and Vn ′ _rR signals at the front position by a predetermined length b from the rear wheel position. It is controlled by RRV. _{FLV = α f · Vn -FL FRV} = α f · Vn -FR RLV = α r · Vn 'rL RRV = α r · Vn' rR In the above equation, the alpha _f proportional constant of the front wheel side, alpha
_r is a proportional constant on the rear wheel side.

The control flow for obtaining the control signal V is completed as described above, and the above flow is repeated thereafter.

As described above, the rear wheel control signals RLV, RR
By determining V from the input sprung vertical velocities Vn ′ _rL and Vn ′ _rR signals at the front position by a predetermined length b from the rear wheel position, it is possible to obtain the control signal V in which the phase shift due to the signal processing is corrected.

That is, FIG. 15 is a diagram showing the phase characteristic of each signal with respect to the input signal frequency. As shown by the dotted line in this figure, the signal processing circuit with respect to the phase of the sprung vertical acceleration G signal as the input signal. In FIG. 15, the phase of the sprung vertical velocity Vn signal as the processed signal processed in step 4 is advanced on the low frequency side and delayed on the high frequency side (delayed in proportion to the magnitude of the frequency). As indicated by the solid line, the phase of the sprung vertical acceleration signal detected on the front wheel side with respect to the phase of the sprung vertical acceleration signal detected on the rear wheel side advances in proportion to the magnitude of the frequency, contrary to the above. Therefore, the control signal formed based on the input sprung vertical acceleration G signal at the front position by a predetermined length b from the rear wheel position in which this phase has advanced is used for the control on the rear wheel side.
On the rear wheel side, it is possible to correct the phase delay due to signal processing so as to eliminate the deterioration of the riding comfort of the vehicle due to the phase delay on the high frequency side of the sprung resonance frequency.

FIG. 20 is a characteristic diagram showing the transmissibility to the sprung with respect to the input frequency, which shows the effect of the first embodiment device by simulation. The dotted line shows the characteristic of the conventional example, and the solid line shows it. This is the characteristic of this embodiment, and as shown in this figure, the transmissibility is reduced on the high frequency side of the sprung resonance frequency, which reduces the feeling of fluttering and lumps during high-speed running. Will be able to improve the ride quality.

Next, among the control operations in the control unit 4, the damping force characteristic control operation of each shock absorber AS based on the control signal V will be described with reference to the flowchart of FIG.

In step 201, it is judged whether or not the control signal V is equal to or more than a predetermined positive threshold value δ _T. If YES, the process proceeds to step 202, and if NO, step 20.
Go to 3.

In step 202, the shock absorber SA is controlled to the extension side hard area HS. Step 203
Then, it is determined whether or not the control signal V is less than or equal to a predetermined negative threshold value -δ _C , and if YES, the process proceeds to step 204, and if NO, the process proceeds to step 205.

At step 204, each shock absorber SA is controlled to the compression side hard area SH. Step 20
5 is determined to be NO in steps 201 and 203, that is, the control signal V has a predetermined positive and negative threshold value δ.
This is a processing step when the value is between _T and −δ _C , and at this time, each shock absorber SA is controlled in the soft region SS.

Next, the operation of damping force characteristic control will be described with reference to the time chart of FIG. When the control signal V based on the sprung vertical velocity Vn changes as shown in this figure,
As shown in the figure, when the control signal V is a value between the predetermined positive and negative threshold values δ _T and −δ _C , the shock absorber SA is controlled to the soft region SS.

Further, the control signal V has a predetermined positive threshold value δ.
_When it becomes equal to or higher than _T , the extension side hard region HS is controlled to fix the compression side to the low damping force characteristic, while the extension side damping force characteristic is changed in proportion to the control signal V. At this time, damping force characteristic C
Controls so that C = kV. Incidentally, k is a proportional constant.

Further, the control signal V is a predetermined negative threshold value-
When it becomes δ _C or less, the compression side hard region SH is controlled to fix the extension side to the low damping force characteristic, while the compression side damping force characteristic is changed in proportion to the control signal V. Also at this time, the damping force characteristic C is controlled so that C = kV.

As described above, in the vehicle suspension system of this embodiment, when the sprung vertical velocity (control signal V) and the sprung / unsprung relative velocity have the same sign (regions b and d in FIG. 18), The skyhook theory is that the stroke side of the shock absorber SA at that time is controlled to have a hard characteristic, and when the different sign (areas a and c in FIG. 18), the stroke side of the shock absorber SA at that time is controlled to have a soft characteristic. The same control as the damping force characteristic control based on can be performed only by the pair of upper and lower G sensors 1 on the front wheel side. Further, when shifting from the region a to the region b and from the region c to the region d, the damping force characteristic is switched without driving the pulse motor 3.

As described above, the vehicle suspension system of this embodiment has the following effects. The phase delay on the high frequency side due to the signal processing for obtaining the signal having the frequency dependence can be eliminated by the control on the rear wheel side, and the riding comfort of the vehicle can be improved.

Compared with the conventional damping force characteristic control based on the skyhook theory, the switching frequency of the damping force characteristic is reduced, so that the control response can be improved and
It is possible to improve durability of the pulse motor and reduce power consumption.

Next, another embodiment of the present invention will be described. In the description of these embodiments, the same components as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted, and only the differences from the first embodiment will be described.

(Second Embodiment) This second embodiment is shown in FIG.
As shown in the sensor layout of Fig. 2, the vehicle body center position ( _FC ) between the left and right shock absorbers SA _FL and SA _FR mounting positions on the front wheel side, and the left and right shock absorbers S on the rear wheel side
A vertical G sensor 1 _FC , 1 _RC is provided at each vehicle center position ( _RC ) between the A _RL , SA _RR mounting positions, and the front wheel side central position obtained from each vertical G sensor 1 _FC , 1 _RC While the damping force characteristic control of the front wheel side shock absorbers SA _FL , SA _FR is performed by the control signal V obtained based on the sprung vertical velocity V _{n -FC} signal in
From the sprung vertical velocity Vn- _RC signal at the center position on the rear wheel side, the sprung vertical velocity Vn ' _rC signal at a position forward of the rear wheel position is calculated, and the control signal V is obtained from this sprung vertical velocity Vn' _rC signal. By the rear wheel side shock absorber S
The damping force characteristic control of A _RL and SA _RR is performed.

Therefore, in this embodiment, the number of upper and lower G sensors is two as compared with the first embodiment, so that the system cost can be reduced.

(Third Embodiment) This third embodiment is shown in FIG.
As shown in the sensor arrangement diagram of FIG. 23 and the system block diagram of FIG. 23, in addition to the pair of left and right up and down G sensors 1 _FL and 1 _FR that detect vertical acceleration at a position rearward by x from the left and right front wheel positions indicated by dotted lines, It is equipped with a vertical G sensor 1 _RR that detects vertical acceleration at the position near the right rear wheel ( _RR ).
Based on the three sprung vertical accelerations G _FL , G _FR , G _RR signals detected by these three vertical G sensors 1 _FL , 1 _FR , 1 _RR , four detection target positions in the vehicle body, that is, dotted lines Sprung vertical acceleration G _f ' _L , G _f ' at the left and right front wheel positions
And _R signals, sprung mass vertical acceleration G _{r 'L,} G _r' at just front position y from the left and right rear wheel position indicated by the dotted line together with the finding in calculating the _R signal, the detection target position of the rear wheels in proportion to the vehicle speed It is designed to be moved in the forward direction of the vehicle.

In FIG. 23, 2 is a vehicle speed sensor and 4 is a vehicle speed sensor.
Reference numeral 1 is a distance x, y calculation unit, 42 is a position correction calculation unit, 43 is a target position acceleration calculation unit, 44 is each component calculation unit, 45 is a speed conversion unit, 46 is a bandpass filter BPF, and 47 is a control signal calculation unit. 48 are damping force characteristic control units.

Next, of the control operations of the control unit 4 of this embodiment, the control operation for obtaining the control signal V of each shock absorber will be described with reference to the flowchart of FIG.

In step 301, as described above, from the three sprung vertical accelerations G _FL , G _FR , G _RR signals of the vehicle body detected by the three vertical G sensors 1 _FL , 1 _FR , 1 _RR , Based on the following equation, the front wheel side sprung vertical acceleration G _f ' _L , G _f ' _R signal at the front wheel position and the rear wheel side sprung vertical acceleration G _r ' _L , G _r ' at a position forward by y from the rear wheel position. _{The R} signal is calculated (see FIG. 22).

[0051]

[Formula 1]

As shown in FIG. 22, in the above equation,
L ₀ is the wheel base, L ₁ is the tread, and L ₂ is the widthwise shift width of the vertical G sensor 1 _RR mounting position with respect to the right rear wheel position.

Further, x and y are linear functions of the vehicle speed (speed) as shown by the following equation, and the target position moves forward as the vehicle speed becomes higher.

X = κ _f · speed + x ₀ y = κ _r · speed + y ₀ where κ _f and κ _r are gains and x ₀ and y ₀ are initial values.

In step 302, the front-side sprung vertical accelerations G _f ' _L , G _f ' at each target position obtained by the calculation.
_{From the R} signal and the rear-spring-side sprung vertical accelerations G _r ' _L , G _r ' _R signals, the bounce component G _B , pitch components G _Pf , G _Pr , roll components G _Rf , G _{Rr of the} vehicle are calculated based on the following equations. Ask for.

G _B = (G _f ' _L + G _f ' _R + G _r ' _L + G _r ' _R ) / 4 G _Pf = ((G _f ' _L + G _f ' _R )-(G _r ' _L + G _r ' _R )) /
_{4 G Pr = ((G r} 'L + G r' R) - (G f 'L + G f' R)) /
In _{4 G Rf = (G f '} R -G f' L) / 2 = G Rr step 303, each component G _B by the said spring vertical _{acceleration, G Pf, G Pr, G} Rf, by integrating the G _Rr Bounce component Vn- _B , pitch component Vn- _Pf , V due to sprung vertical velocity
n _-Pr, roll component Vn _-Rf, converts to Vn _-Rr signal, by treatment with constructed bandpass filter BPF with a high-pass filter and 2.5Hz low pass filter 0.5 Hz, unnecessary frequency components Find the removed signal.

Each component signal is given a positive value in the upward direction and a negative value in the downward direction.

At step 304, the control signal V of each shock absorber SA is obtained based on the following equation.

[0059] _{FLV = α f · Vn -B +} β f · Vn -Pf + γ f · Vn -Rf FRV = α f · Vn -B + β f · Vn -Pf -γ f · Vn -Rf RLV = α r · Vn _-B + [beta] _r * Vn- _Pr + [gamma] _r * Vn- _Rr RRV = [alpha] _r * Vn- _B + [beta] _r * Vn- _{Pr- [} gamma] _r * Vn- _{Rr In} the above formula, [alpha] _f , [beta] _f , [gamma] _f Are the proportional constants on the front wheel side, α _r , β _r , γ _r are the proportional constants on the rear wheel side, and FL is the front wheel left side, FR is the front wheel right side, RL is the rear wheel left side, and RR is the rear wheel. The right side is shown respectively, and the positions of the shock absorbers SA _FL , SA _FR , SA _RL , and SA _RR are made to correspond (the same applies below).

The control flow for obtaining the control signal V is completed as described above, and the above flow is repeated thereafter.

That is, in this embodiment, when the vehicle receives an input from the road surface during traveling, the sprung vertical speed at the rear wheel position shown by the chain line is shown in (a) and (b) of FIG. 25, respectively. The amount of phase advance T, T'of the sprung vertical velocity signal at the front wheel position shown by the solid line with respect to the signal decreases as the vehicle speed increases, while FIG. 2 shows the phase delay state of the sprung vertical velocity signals a, b, c and d at the sprung vertical velocity detection positions A, B, C and D shown in FIG.
As is clear from the time chart of No. 7, in view of the fact that the amount of advance of the phase at the predetermined front position with respect to the rear wheel position becomes larger as it goes to the front of the vehicle (approaching to the front wheel position A),
By configuring a configuration in which a predetermined front position from the rear wheel position is moved forward in proportion to the vehicle speed, it is possible to correct in a direction that eliminates fluctuations in the correction amount of the phase delay due to changes in the vehicle speed. Even in the state, it is possible to obtain an effect that it is possible to improve deterioration of the riding comfort of the vehicle.

In this embodiment, as the vertical G sensor, a pair of vertical G sensors 1 _FL and 1 _FR on the front wheel side and a vertical G sensor 1 _RR on the right rear wheel position ( _RR ) are used. It is also possible to adopt a system configuration in which one vertical G sensor is provided at each central position on the rear wheel side.

Although the embodiment has been described above, the specific structure is not limited to this embodiment, and the present invention includes a design change and the like without departing from the scope of the invention.

For example, in the embodiment, the case where the vertical G sensor is used as the vertical movement detecting means of the vehicle is shown, but the relative displacement between the sprung and unsprung parts, the relative speed sensor, or the like, or a combination of both is used. You can

Further, in the embodiment, when controlling the one stroke side to the hard characteristic, the shock absorber having the structure in which the opposite stroke side has the soft characteristic is used, but the damping force characteristics on the extension stroke and the compression stroke side are It can also be applied to a system using a shock absorber having a structure that changes simultaneously and in the same direction.

In the first and second embodiments, the predetermined front position from the rear wheel position is determined based on the sprung vertical acceleration signals from the front and rear vertical G sensors provided at the front wheel position and the rear wheel position, respectively. Although the sprung vertical acceleration of the vehicle body is calculated by the above, the vertical G sensor may be directly provided at a predetermined front position from the target rear wheel position. In this case, the vertical G sensor is A rear wheel side vertical movement detecting means is constituted.

Further, it is of course possible to arbitrarily combine or combine the respective elements in the respective embodiments between the respective embodiments.

[0068]

As described above, in the vehicle suspension system of the present invention, the front wheel vertical movement detecting means for detecting the vertical movement of the front wheel side of the vehicle body and the vertical direction of the vehicle body at a predetermined front position relative to the rear wheel. A signal for forming a processing signal having frequency dependency from a rear wheel vertical movement detecting means for detecting a behavior and a vertical behavior signal at a predetermined front position from the rear wheel obtained by the rear wheel vertical movement detecting means. A processing circuit,
It is formed on the basis of a processing signal by a front wheel control section for performing damping force characteristic control of the front wheel side shock absorber by a control signal based on the front wheel vertical movement signal obtained by the front wheel vertical movement detection means, and a processing signal by the signal processing circuit. High frequency by signal processing for obtaining a signal having frequency dependence by having a configuration including damping force characteristic control means having a rear wheel control unit for performing damping force characteristic control of the rear wheel side shock absorber by a control signal. There is an effect that the phase delay on the side is eliminated by the control on the rear wheel side, and the riding comfort of the vehicle can be improved.

Further, in the vehicle suspension system according to the fourth aspect of the present invention, the predetermined front position from the rear wheel position is moved forward in proportion to the vehicle speed. Can be corrected in a direction to eliminate the fluctuation, and thus, the deterioration of the riding comfort of the vehicle can be improved in any vehicle speed state.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a claim showing a vehicle suspension device of the present invention.

FIG. 2 is a structural explanatory view showing a vehicle suspension device of the first embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension system of the first embodiment.

FIG. 4 is a sectional view showing a shock absorber applied to the device of the first embodiment.

FIG. 5 is an enlarged cross-sectional view showing a main part of the shock absorber.

FIG. 6 is a damping force characteristic diagram corresponding to the piston speed of the shock absorber.

FIG. 7 is a damping force characteristic diagram corresponding to the step position of the pulse motor of the shock absorber.

FIG. 8 is a K of FIG. 5 showing a main part of the shock absorber.
FIG.

FIG. 9 is an L of FIG. 5 showing a main part of the shock absorber.
It is a LM sectional view.

FIG. 10 is a sectional view taken along line NN of FIG. 5, showing a main part of the shock absorber.

FIG. 11 is a damping force characteristic diagram of the shock absorber when the extension side is hard.

FIG. 12 is a damping force characteristic diagram of the shock absorber in a soft state on the extension side and the compression side.

FIG. 13 is a damping force characteristic diagram of the shock absorber in a compression side hard state.

FIG. 14 is a block diagram showing a signal processing circuit of the first embodiment device.

FIG. 15 is a diagram showing a phase characteristic of each signal with respect to an input signal frequency in the device of the first embodiment.

FIG. 16 is a flowchart showing a control operation for obtaining a control signal, among the control operations in the control unit of the first embodiment device.

FIG. 17 is a flowchart showing a damping force characteristic control operation of the control operations in the control unit of the first embodiment device.

FIG. 18 is a time chart showing a damping force characteristic control operation of the control operations in the control unit of the first embodiment device.

FIG. 19 is a sensor layout view of the device of the first embodiment as seen from the vehicle side surface.

FIG. 20 is a transmissivity characteristic diagram for a sprung portion with respect to an input frequency, showing the effect of the simulation of the device of the first embodiment.

FIG. 21 is a sensor layout view of the device of the second embodiment as viewed from the top surface of the vehicle.

FIG. 22 is a sensor layout view of the device of the third embodiment as viewed from the top surface of the vehicle.

FIG. 23 is a system block diagram of a third embodiment device.

FIG. 24 is a flowchart showing a control operation for obtaining a control signal, among the control operations in the control unit of the third embodiment device.

FIG. 25 is a time chart showing a phase delay state of the sprung vertical velocity signal at the rear wheel position with respect to the sprung vertical velocity signal at the front wheel position in the third embodiment device. B) indicates high vehicle speed.

FIG. 26 is a diagram showing a sprung vertical velocity detection position as seen from the side of the vehicle, for explaining the operation of the third embodiment device.

FIG. 27 is a time chart showing a phase delay state of the sprung vertical velocity signal at each sprung vertical velocity detection position shown in FIG. 26.

[Explanation of symbols]

a damping force characteristic changing means b ₁ front wheel side shock absorber b ₂ rear wheel side shock absorber c front wheel side vertical movement detection means d rear wheel side vertical movement detection means e signal processing circuit f front wheel control section g rear wheel control section h damping force Characteristic control means j Vehicle speed sensor

Claims (4)

[Claims] 1. A front-wheel-side shock absorber and a rear-wheel-side shock absorber, which are interposed between a vehicle body side and each wheel side and whose damping force characteristic changing means can change the damping force characteristic, and a front-and-lower direction of a front wheel side in a vehicle body. Front-wheel-side vertical movement detection means for detecting behavior, rear-wheel-side vertical movement detection means for detecting vertical movement at a predetermined front position of the rear wheel in the vehicle body, and rear-wheel-side vertical movement detection means A signal processing circuit for forming a processed signal having frequency dependence from the vertical behavior signal at a more predetermined front position, and a control signal based on the front wheel vertical behavior signal obtained by the front wheel vertical behavior detection means. The front wheel control section that controls the damping force characteristic of the front wheel side shock absorber, and the rear wheel shock absorber by the control signal generated based on the processing signal by the signal processing circuit. Vehicle suspension system, characterized in that it and a damping force characteristic control means having a wheel control unit after performing a damping force characteristic control of the bus. 2. The vehicle suspension system according to claim 1, wherein the rear wheel side vertical movement detecting means is composed of a vertical movement sensor provided at a predetermined front position from the rear wheel position. 3. The rear wheel vertical movement detecting means includes a rear wheel vertical movement sensor provided near the rear wheel, and a rear wheel vertical movement signal and a front wheel detected by the rear wheel vertical movement sensor. 2. The vehicle according to claim 1, further comprising a computing means for computing a vertical behavior signal at a predetermined front position from the rear wheel position based on the front wheel side vertical behavior signal detected by the side vertical behavior detection means. Suspension system. 4. The vehicle suspension system according to claim 3, further comprising a vehicle speed sensor for detecting a vehicle speed of the vehicle, wherein the vehicle suspension moves a predetermined front position from the rear wheel position in proportion to the vehicle speed.