JPH07215036A - Input acceleration computation device for vehicle - Google Patents

Abstract

PURPOSE:To provide an input acceleration computation device which can obtain pure sprung vertical acceleration and/or pure input lateral acceleration in a vehicle, even at transient roll of the vehicle due to steering. CONSTITUTION:This input acceleration computation device is provided with a sprung vertical acceleration detecting means (a) to detect the sprung vertical acceleration on a prescribed position of a vehicle, a lateral acceleration detecting means (b) to detect the lateral acceleration of the vehicle, and a roll angle detecting means (c) to detect the roll angle of the vehicle. It is also provided with an input acceleration computation means (d) to compute pure sprung vertical acceleration of the vehicle and/or pure lateral acceleration of the vehicle without containing detection error due to roll of the vehicle, based on combined vector of the sprung vertical acceleration of detected by the means (a) and the lateral acceleration detected by the means (b), and the roll angle detected by the means (c).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input acceleration calculating device for obtaining an input acceleration of a vehicle for controlling damping force characteristics of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system having an input acceleration detecting means for controlling a damping force characteristic of a shock absorber, for example, one disclosed in JP-A-61-163011 is known. .

This conventional vehicle suspension system detects the sprung vertical speed and the relative speed between the sprung and unsprung parts, and when both have the same sign, the damping force characteristic is made hard, and when both have the different sign, the damping is performed. The damping force characteristic control based on the Skyhook theory, such as making the force characteristic soft, was performed independently for the four wheels. Then, the sprung vertical velocity has been obtained by filtering the sprung vertical acceleration signal detected by the sprung vertical acceleration sensor.

[0004]

However, in the above-mentioned conventional device, since the sprung vertical acceleration sensor is used as described above, there are the following problems.

That is, when the vehicle rolls, such as when the vehicle is turning, the detection axis direction of the sprung vertical acceleration sensor is inclined by the roll angle, so that the other axis component (roll angle) due to the lateral acceleration. The vertical acceleration component of the lateral acceleration due to is detected, and therefore, there is a problem that accurate damping force characteristic control cannot be performed.

Further, even when the lateral acceleration of the vehicle is detected by the lateral acceleration sensor, the same problem as described above occurs when the vehicle rolls.

The present invention has been made by paying attention to the above-mentioned conventional problems. Even when the vehicle is in a transient roll due to steering, a pure input spring top / bottom acceleration and / or a pure input lateral direction in the vehicle are generated. It is an object of the present invention to provide an input acceleration calculation device capable of obtaining acceleration.

[0008]

In order to achieve the above-mentioned object, an input acceleration calculation device for a vehicle according to claim 1 of the present invention has a spring at a predetermined position in the vehicle as shown in the claim correspondence diagram of FIG. A sprung vertical acceleration detecting means a for detecting a vertical acceleration, a lateral acceleration detecting means b for detecting a lateral acceleration of the vehicle, a roll angle detecting means c for detecting a roll angle of the vehicle, and a sprung vertical acceleration detecting means. The detection error due to the roll of the vehicle is not included based on the combined vector of the sprung vertical acceleration detected by a and the lateral acceleration detected by the lateral acceleration detecting means b and the roll angle detected by the roll angle detecting means c. The input acceleration calculation means d for calculating the pure sprung vertical acceleration of the vehicle and / or the pure lateral acceleration of the vehicle.

According to a second aspect of the present invention, the lateral acceleration detecting means detects the difference in rotational speed between the left and right wheels, and the left and right wheel speed difference detecting means detects the difference in rotational speed between the left and right wheels. The means is composed of a lateral acceleration calculating means for calculating the lateral acceleration.

According to a third aspect of the present invention, in the input acceleration computing device for a vehicle, the roll angle detecting means detects the difference in rotational speed between the left and right wheels, and the left and right wheel speed difference detecting means detects the difference in rotational speed between the left and right wheels. The roll angle calculating means calculates the roll angle.

According to a fourth aspect of the present invention, in the input acceleration computing device for a vehicle, the lateral acceleration detecting means is a lateral acceleration sensor provided on a spring of the vehicle, and the roll angle detecting means is a lateral acceleration sensor. The roll angle calculating means calculates the roll angle of the vehicle from the lateral acceleration of the vehicle detected by the method.

[0012]

In the vehicle input acceleration calculating device of the present invention, in the input acceleration calculating means, a composite vector of the sprung vertical acceleration detected by the sprung vertical acceleration detecting means and the lateral acceleration detected by the lateral acceleration detecting means, Based on the roll angle of the vehicle detected by the roll angle detection means, a pure sprung vertical acceleration of the vehicle and / or a pure lateral acceleration of the vehicle that does not include a detection error due to the roll of the vehicle are calculated.

Therefore, even during a vehicle transient roll due to steering, it is possible to determine a pure input sprung vertical acceleration and / or a pure input lateral acceleration in the vehicle, which allows, for example, a pure vehicle input. Accurate damping force characteristic control based on the acceleration signal can be performed.

[0014]

Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 2 is a structural explanatory view showing a vehicle suspension system to which an input acceleration computing device for a vehicle according to a first embodiment of the present invention is applied. The vehicle suspension system is interposed between a vehicle body and four wheels. Four shock absorbers SA ₁ , SA ₂ , SA ₃ , SA ₄
(Note that in describing the shock absorber, when these four are collectively referred to, and when describing their common configuration, they are simply referred to as SA.). Then, each shock absorber SA ₁ , SA
_2, SA _3, SA ₄ to the vehicle body in the vicinity of the position, sprung mass vertical acceleration sensor for detecting acceleration in the vertical direction (hereinafter, the vertical G
That sensor) ₁ 1, 1 _2, 1 _3, 1 ₄ (Incidentally, the shock absorbers are numbers _{1, 2, 3, 4} in the lower right SA _1, SA _2,
It corresponds to the positions of SA ₃ and SA ₄ . The same applies to the following. ) Is provided, and lateral acceleration sensors (hereinafter referred to as lateral G sensors) 2 ₁ and 2 ₂ that detect lateral acceleration of the vehicle are provided at the center positions in the width direction of the front wheel position and the rear wheel position. . The sprung vertical acceleration signal is obtained as a positive value when the acceleration direction is upward, and is obtained as a negative value when the acceleration direction is downward, and the lateral acceleration signal is obtained in the direction from the right wheel to the left wheel in the acceleration direction. Is obtained as a positive value, and when the direction is from the left wheel to the right wheel, a negative value is obtained. Also, in the vicinity of the driver's seat, the vertical G sensors 1 ₁ , 1 ₂ , 1 ₃ , 1 ₄ ,
Further, a control unit 4 is provided which inputs signals from the lateral G sensors 2 ₁ and 2 ₂ and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above-mentioned configuration. The control unit 4 is provided with an interface circuit 4a, a CPU 4b, and a drive circuit 4c, and the interface circuit 4a includes the above-mentioned vertical G sensors 1 respectively.
Signals from ₁ , 1 ₂ , 1 ₃ and 1 ₄ and both lateral G sensors 2 ₁ and 2 ₂ are input.

A signal processing circuit shown in FIG. 14 is provided in the interface circuit 4a. That is, in the figure, the LPF 1 is the upper and lower G sensors 1 ₁ , 1
Signals sent from ₂ , 1 ₃ , 1 ₄ and each lateral G sensor 2 ₁ , 2 ₂ (front wheel right spring sprung vertical acceleration FR-G, front wheel left spring sprung vertical acceleration FL-G, rear wheel right sprung vertical acceleration RR -G, to remove the noise in the high frequency range (30Hz or more) from the vertical spring acceleration RL-G on the left side of the rear wheel, the lateral acceleration YG-F on the front wheel side, and the lateral acceleration YG-R on the rear wheel side. Is a low-pass filter circuit.

The A / D is a conversion circuit for converting an analog signal into a digital signal. Reference numerals 50a to 50j are arithmetic circuits. That is, as shown in the respective equations in this figure,
Reference numeral 50a is an arithmetic circuit for _obtaining the sprung vertical acceleration G _BF at the center position on the front wheel side by dividing the signal obtained by adding the front wheel right sprung vertical acceleration FR-G and the front wheel left sprung vertical acceleration FL-G by 2. is there.

50b is a vertical acceleration RR-G on the right side of the rear wheel.
This is a calculation circuit for _obtaining the sprung vertical acceleration G _BR at the center position on the rear wheel side by dividing a signal obtained by adding the rear wheel left-side sprung vertical acceleration RL-G by 2.

50c is the vertical acceleration FR-G on the right side of the front wheel.
Is a calculation circuit for obtaining the roll acceleration G _R at the front wheel position by dividing the signal obtained by subtracting the left-side sprung vertical acceleration FL-G from the front wheel by 2.

50d is an arithmetic circuit for obtaining a constant α from the maximum value αmax of the constant, the damping force position position of the shock absorber SA and the maximum damping force position Pmax, and 50e is the arithmetic circuit 50d.
This is a calculation circuit for obtaining the roll angle θ _{R of the} vehicle from the constant α obtained in step 1 and the value of the front wheel side lateral acceleration YG-F. That is,
As shown in the time chart of FIG. 15, since the lateral acceleration YG-F of the vehicle and the roll angle θ _R have the same phase as the characteristic of the vehicle, the lateral acceleration YG-F is multiplied by a predetermined constant α. Then, the roll angle θ _R is obtained and the constant α
Is a function of the damping force characteristic (damping force position) of the shock absorber SA at that time, so that the roll angle θ _R value can be made to correspond to the change of the roll characteristic based on the change of the damping force characteristic as shown by the chain line. It is the one.

50f is an arithmetic circuit for obtaining a pure sprung vertical acceleration g _BF at the front wheel side central position, and 50g is an arithmetic circuit for obtaining a pure sprung vertical acceleration g _BR at the rear wheel side central position, Reference numeral 50h is an arithmetic circuit for obtaining the pure lateral acceleration g _SF at the front wheel side central position, and 50i is an arithmetic circuit for obtaining the pure lateral acceleration g _SR at the rear wheel side central position. That is, FIG. 16 shows the sprung vertical acceleration G _BF (G _BR ) at the vehicle center position and the lateral acceleration YG-F (YG at the vehicle center position when the vehicle is rolled (inclined in the left-right direction by the roll angle θ _R ). FIG. 14 is a diagram showing the relationship between the value of pure sprung vertical acceleration g _BF (g _BR ) and the value of pure lateral acceleration g _SF (g _SR ) with respect to the value of −R). Each formula can be derived. In addition,
The part surrounded by the dotted line in these arithmetic expressions is a part for obtaining θ in FIG.

50j is a pure lateral acceleration g _SF from the center position on the front wheel side to a pure lateral acceleration g from the center position on the rear wheel side.
_This is an arithmetic circuit that calculates the pitch acceleration g _P by dividing the signal minus _SR by 2.

The LPF 2 is provided with respective acceleration signals (g _BF , g _BR ,
This is a low-pass filter circuit for integrating each of G _R and g _P (delaying the phase by 90 °) to convert into a sprung vertical velocity.

The HPF represents each lateral acceleration signal (g _SF , g
It is a high-pass filter circuit for differentiating each _SR (advancing the phase by 90 °) and converting it into a lateral acceleration change rate (lateral jerk).

The BPF is a bandpass filter circuit for obtaining a signal in a required frequency range from each of the converted sprung vertical velocity signals and lateral acceleration change rate signals. A bandpass filter for obtaining a bounce velocity signal V _Bf on the front wheel side and a bounce velocity signal V _Br on the rear wheel side by passing a frequency range including a frequency, and a pitch velocity by passing a frequency range including a pitch resonance frequency. A bandpass filter for obtaining the signal V _P , a bandpass filter for passing a frequency range including the roll resonance frequency to obtain the roll speed signal V _R , and a frequency region (0 to 3 Hz) in which high frequency components are cut off. A bandpass filter for obtaining a lateral acceleration change rate signal V _{Rf at the} front wheel position and a lateral acceleration change rate signal V _Rr at the rear wheel position.

As described above, in this embodiment, the low-pass filter circuit LPF2 shown in FIG. 14 constitutes the sprung vertical velocity calculation means in the claims, and the lateral G sensor 2 and FIG.
And the high-pass filter circuit HPF constitute the lateral acceleration detecting means in the claims.

Next, FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A is a cylinder 30, a piston 31 defining the cylinder 30 into an upper chamber A and a lower chamber B, an outer cylinder 33 having a reservoir chamber 32 formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber 32. Defining the base 34 and the piston 31
A guide member 35 that guides the sliding of the piston rod 7 that is connected to the vehicle, a suspension spring 36 that is interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

Next, FIG. 5 is an enlarged cross-sectional view showing the 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. Further, a stud 38 penetrating the piston 31 is screwed and fixed to the bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. Communication for forming a flow path (an expansion-side second flow path E, an expansion-side third flow path F, a bypass flow path G, and a compression-side second flow path J described later) that connects the upper chamber A and the lower chamber B with each other. A hole 39 is formed and this communication hole 3
An adjuster 40 for changing the flow passage cross-sectional area of the flow passage is rotatably provided inside the passage 9. Also, the stud 38
The communication hole 3 is formed on the outer peripheral portion of the communication hole 3 depending on the direction of fluid flow.
An expansion-side check valve 17 and a pressure-side check valve 22 that allow and block the flow passage formed by 9 are provided. It should be noted that this adjuster 40 corresponds to the pulse motor 3
Is rotated via the control rod 70 (see FIG. 4). Also, the stud 38 has
A first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed in this order from the top.

On the other hand, in the adjuster 40, the hollow portion 19 is formed, the first lateral hole 24 and the second lateral hole 25 which communicate the inside and the outside are formed, and the 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 characteristic can be changed in multiple stages on both the extension side and the compression side by the characteristic shown in FIG. 6 by rotating the adjuster 40. That is, as shown in FIG.
Both the pressure side are soft (hereinafter soft area SS
When the adjuster 40 is rotated counterclockwise from
Only the extension side can change the damping force characteristic in multiple stages, and the compression side becomes a region fixed to the low damping force characteristic (hereinafter referred to as the extension side hard region HS). Conversely, when the adjuster 40 is rotated clockwise, The damping force characteristic can be changed in multiple steps only on the compression side, and the extension side is a region fixed to the low damping force characteristic (hereinafter, referred to as compression side hard region SH).

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, the operation of the control unit 4 for controlling the drive of the pulse motor 3 will be described with reference to the flowchart of FIG. Note that this control is separately performed for each shock absorber SA.

In step 101, in the signal processing circuit shown in FIG. 14, each sprung G sensor 1 ₁ , 1 ₂ , 1 ₃ ,
From the acceleration signals FR-G, FL-G, RR-G, RL-G, YG-F, and YG-R obtained from the 1 ₄ and both lateral G sensors 2 ₁ and 2 ₂ , the bounce speed signal V _Bf on the front wheel side , determined bounce velocity signals V _Br of the rear wheel side, the pitch rate signal V _P, roll velocity signal V _R, the front wheel position lateral acceleration changing rate signal V _Rf, a lateral acceleration change rate signal V _Rr of the rear wheel position, respectively.

In step 102, the following equation is used,
A control signal V (V _FR , V _FL , V _RR , V _RL ) for the position of each wheel is calculated based on each signal V _Bf , V _Br , V _P , V _R , V _Rf , V _Rr . Front wheel right V _FR = α _f · V _Bf + β _f · V _P + r _f · V _R + δ _f · V _Rf Front wheel left V _FL = α _f · V _Bf + β _f · V _P −r _f · V _R −δ _f · V _Rf Rear wheel right V _RR = α _r · V _Br −β _r · V _P + r _r · V _R + δ _r · V _Rr Rear wheel left V _RL = α _r · V _Br −β _r · V _P −r _r · Note V _R -δ _r · V _Rr, is _{α f, β f, γ f} , δ f, the gain of the front wheel _{α r, β r, γ r} , δ r is the gain of the rear wheel.

In each equation, the first part bounded by α _f and α _r is the bounce rate, and β _f and β _r
The part enclosed by is the pitch rate, and γ _f and γ _r
The part that is bounded by is the steady roll rate, and δ _f ,
The part bounded by δ _r is the transient roll rate during steering.

In step 103, it is determined whether the control signal V has a positive value, and if YES, step 10
4. If NO, proceed to step 105. In step 104, the shock absorber SA is controlled to the extension side hard area HS. In step 105, it is determined whether the control signal V is 0, and if YES, step 10
6, the process proceeds to step 107 if NO.

In step 106, the shock absorber SA is controlled in the soft area SS. Step 107
This step is displayed for the sake of convenience, and if the determination at step 103 and step 105 is NO, the control signal V is a negative value, and in this case the processing proceeds to step 108. In step 108, the shock absorber SA is controlled to the compression side hard area SH.

Next, the operation of the embodiment apparatus will be described with reference to the time chart of FIG. When the control signal V changes as shown in this figure, as shown in the figure, when the control signal V is 0, the shock absorber SA is set to the soft region SS.
To control.

When the control signal V has a positive value, the extension side hard area HS is controlled to fix the compression side to the low damping force characteristic, while the extension side damping force characteristic is proportional to the control signal V. change. At this time, the damping force characteristic C is controlled so that C = k ₁ · V. The k ₁ is a proportional constant on the extension side.

When the control signal V becomes a negative value, 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. To do. At this time as well, the damping force characteristic C is controlled so that C = k ₂ · V. The k ₂ is a proportional constant on the pressure stroke side.

Further, in the time chart of FIG.
In the region a, the control signal V is reversed from a negative value (downward) to a positive value (upward), but at this time, the relative speed is still a negative value (the stroke of the shock absorber SA is the pressure stroke side). Therefore, at this time, the shock absorber SA is controlled to the extension side hard area HS based on the direction of the control signal V, and therefore, the stroke of the shock absorber SA at that time is in this area. The pressure stroke side has soft characteristics.

Area b is an area in which the control signal V remains a positive value (upward) and the relative speed is switched from a negative value to a positive value (the stroke of the shock absorber SA is on the extension side). Therefore, at this time, the shock absorber SA is controlled in the extension side hard region HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. Therefore, in this region, the shock at that time is present. The extension side, which is the stroke of the absorber SA, has a hardware characteristic proportional to the value of the control signal V.

In the region c, the control signal V is reversed from a positive value (upward) to a negative value (downward).
At this time, the relative speed is still a positive value (shock absorber S
Since the stroke of A is on the extension side), at this time, the shock absorber SA is controlled to the compression side hard zone SH based on the direction of the control signal V. Therefore, in this zone, The extension side, which is the stroke of the shock absorber SA, has soft characteristics.

In the area d, the control signal V remains a negative value (downward) and the relative speed changes from a positive value to a negative value (the stroke of the shock absorber SA is the extension stroke side). At this time, the shock absorber SA is controlled to the compression side hard region SH based on the direction of the control signal V, and the stroke of the shock absorber is also the pressure stroke.
Therefore, in this area, the shock absorber SA at that time
The pressure stroke side, which is the stroke of, has a hardware characteristic proportional to the value of the control signal V.

As described above, in this embodiment, when the sprung vertical velocity and the relative velocity between the sprung portion and the unsprung portion have the same sign (region b, region d), the shock absorber S at that time.
Damping force characteristic control based on the skyhook theory, in which the stroke side of A is controlled to have a hard characteristic, and when the signs are different (area a, area c), the stroke side of the shock absorber SA at that time is controlled to have a soft characteristic The same control as above is performed without detecting the relative speed between the sprung and unsprung parts. Further, in this embodiment, when the region a shifts to the region b and the region c shifts to the region d, the damping force characteristic is switched without driving the pulse motor 3.

Next, the operation of the control unit 4 during straight running and steering of the vehicle will be described. (A) When traveling straight ahead When the vehicle is traveling straight ahead, the lateral acceleration does not act on the vehicle, so that the lateral acceleration change rate signals V _Rf and V _Rr become 0. Therefore, the bounce based on the sprung vertical velocity is caused. The damping force characteristic control of each shock absorber SA is performed by the control signal obtained from the rate, the pitch rate, and the steady roll rate. So not only bounce,
Sufficient vibration damping can be exhibited even for vehicle behavior in which bounce, pitch, and steady roll are kneaded.

(B) At the time of steering When steering is performed, a roll is generated in the vehicle and a lateral acceleration acts on the vehicle at the same time, so that lateral acceleration change rate signals V _Rf and V _Rr are generated according to the change rate. , Thereby, the control signal V changes. Therefore, the roll of the vehicle body based on the steering can be sufficiently suppressed.

[0049] Incidentally, the lateral acceleration YG-F to the vehicle by steering operation, the YG-R roll the vehicle acts occurs, the upper and lower amount corresponding to the roll angle theta _R G sensor 1 _1, 1 _2, 1 _3, 1
_Since the detection axis direction of ₄ is inclined, the values of the detected sprung vertical accelerations G _BF and G _BR are lateral accelerations YG-F and YG-R.
As described above, the lateral acceleration YG detected by the lateral G sensors 2 ₁ and 2 ₂ is included because the other axis component due to
-The roll angle θ _{R of the} vehicle is calculated based on the value of F and the damping force position position at that time, and the pure sprung vertical accelerations g _BF and g _BR and the pure lateral acceleration g _SF are calculated from this calculated value. , G _SR values are calculated.
Even during a transient roll of the vehicle based on steering, it is possible to prevent the generation of an inaccurate damping force characteristic control state due to a detection error.

As described above, in this embodiment, the effects listed below can be obtained. Since sufficient control force can be generated not only for bounce but also for pitch and steady roll, it is possible to provide an input acceleration calculation device for a vehicle that is excellent in riding comfort and steering stability.

Even during a transient roll of the vehicle based on steering, it is possible to determine a pure input sprung vertical acceleration and a pure input lateral acceleration of the vehicle, and thus an accurate input based on a pure vehicle input acceleration signal. It becomes possible to perform various damping force characteristic control.

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
The durability of the pulse motor 3 can be improved.

(Second Embodiment) Next, a second embodiment will be described. In describing this embodiment, only differences from the first embodiment will be described. The same reference numerals as those used in the first embodiment indicate the same objects.

In the second embodiment, among the control contents of the control unit 4, the arithmetic expression for obtaining the roll angle θ _R is different from that of the first embodiment.

That is, in this embodiment, the roll angle θ _R is obtained by the following equation, but α ₀ is a fixed constant. θ _R = YG-F · α ₀ And the arithmetic circuit 50 for _obtaining the values of the pure sprung vertical accelerations g _BF and g _BR and the pure lateral accelerations g _SF and g _SR.
As the value of the roll angle θ _R in the arithmetic expressions of f, 50g, 50h, and 50i, the roll angle data before the preview delay time Δt obtained by the following equation is used. Δt = (P / Pmax) Δtmax Note that Δtmax indicates the maximum value of the preview delay time Δt.

FIG. 19 is a plan view for explaining the mounting position of the lateral G sensor 2, and the mounting point of the lateral G sensor 2 indicated by a black square is a minimum preview delay time Δt Δtm.
When in (0), the roll angle and the lateral acceleration are in phase, and the dotted line indicates that the roll angle and the lateral acceleration are in phase when the preview delay time Δt is the maximum value Δtmax. is there.

That is, in this embodiment, when the preview delay time Δt becomes long (Δtmin → Δtmax) as shown by the roll angle θ _R characteristic with respect to the lateral acceleration YG-F in FIG.
As shown in FIG. 21, when the damping force characteristic is increased (Pmin →
Pmax) has a value close to the lateral acceleration YG-F characteristic with respect to the roll angle θ _R , so the preview delay time Δt
As a function of the damping force characteristic, the fixed constant α ₀ is apparently a function of the damping force characteristic.

(Third Embodiment) Next, a third embodiment will be described. In this embodiment, the lateral acceleration detecting means for detecting the lateral acceleration of the vehicle and the roll angle detecting means for detecting the roll angle of the vehicle are different from those in the first embodiment. Since other configurations are the same as those of the first embodiment, only different points will be described. The same reference numerals as those used in the first embodiment indicate the same objects.

First, FIG. 22 is a structural explanatory view showing a vehicle suspension system to which the vehicle input acceleration computing device of the third embodiment is applied. As shown in this figure, in this embodiment, the first embodiment is used. Instead of the lateral G sensors 2 ₁ and 2 ₂ in the example, a left wheel speed sensor 5L that detects the wheel speed VL of the left wheel
And a right wheel speed sensor 5R for detecting the wheel speed VR of the right wheel.

Next, FIG. 23 is a system block diagram showing the above-mentioned configuration. As shown in this figure, the interface circuit 4a includes vertical G sensors 1 ₁ , 1 ₂ , 1 ₃ , 1 1.
₄ and the signals from the left and right wheel speed sensors 5L and 5R are input.

In the interface circuit 4a, as shown in detail in FIG. 24, the left and right wheel speeds for obtaining the rotational speed difference VLR of the left and right wheels based on the signals from the left and right wheel speed sensors 5L, 5R. From the difference calculation circuit 5a and the rotational speed difference VLR between the left and right wheels, the lateral acceleration YG of the vehicle is calculated.
There is provided a signal processing circuit including a lateral acceleration calculation circuit 5b that calculates the roll acceleration and a roll angle calculation circuit 5c that calculates the roll angle θ _{R of the} vehicle from the rotational speed difference between the left and right wheels.

That is, in this embodiment, as shown in the measured data of FIG. 25, the phase characteristics of the data of the left and right wheel speed difference VLR and the measured data of the roll angle of the vehicle match, and the roll angle of the vehicle and the vehicle Since there is a vehicle characteristic that the lateral acceleration of the vehicle has the same phase, the lateral acceleration YG of the vehicle and the roll angle θ of the vehicle are calculated based on the following equation from the rotational speed difference VLR between the left and right wheels.
_R and _R are calculated.

YG = VLR · α θ _R = VLR · β Note that α and β are coefficients for correcting the signal levels of the lateral acceleration YG and the roll angle θ _R.

Therefore, in this embodiment, when applied to a vehicle provided with a wheel speed sensor such as an anti-skid brake system, the installation of a lateral acceleration sensor or the like can be omitted, thus reducing the system cost. Will be able to.

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 within a range not departing from the gist of the invention.

For example, in the embodiment, the lateral G sensor and the left and right wheel speed sensors are used as means for detecting the lateral acceleration and the roll angle of the vehicle. However, other means such as a steering sensor and a yaw rate sensor are used. Means can be used.

Further, in the third embodiment, the lateral acceleration of the vehicle and the roll angle of the vehicle are calculated from the rotational speed difference between the left and right wheels. However, based on the rotational speed difference between the left and right wheels, Either one of the lateral acceleration of the vehicle and the roll angle of the vehicle may be calculated first, and the other value may be calculated based on the calculation result.

[0068]

As described above, the vehicle input acceleration computing device of the present invention detects the sprung vertical acceleration detecting means for detecting the sprung vertical acceleration at a predetermined position in the vehicle and the lateral acceleration of the vehicle. Lateral acceleration detection means, roll angle detection means for detecting the roll angle of the vehicle, composite vector of sprung vertical acceleration detected by sprung vertical acceleration detection means and lateral acceleration detected by the lateral acceleration detection means, and roll Input acceleration calculation means for calculating pure sprung vertical acceleration of the vehicle and / or pure lateral acceleration of the vehicle that does not include a detection error due to the roll of the vehicle based on the roll angle detected by the angle detection means; With this configuration, even when the vehicle is in a transient roll state based on steering, pure vertical acceleration on the spring and / or
Alternatively, it is possible to obtain a pure input lateral acceleration, which has the effect of enabling accurate damping force characteristic control based on a pure vehicle input acceleration signal, for example.

According to another aspect of the vehicle input acceleration computing device of the present invention, the lateral acceleration detecting means detects the lateral speed difference between the left and right wheels by detecting the lateral speed difference between the right and left wheels. Since the vehicle is provided with the lateral acceleration calculating means for calculating the directional acceleration, it is not necessary to separately provide the lateral G sensor in the vehicle having the left and right wheel speed detecting means, so that the system cost can be reduced. The effect of becoming is obtained.

Further, in the vehicle input acceleration calculating device according to the present invention, the roll angle detecting means detects the rotational speed difference between the left and right wheels, and the left and right wheel speed difference detecting means detects the rotational speed difference between the left and right wheels. Since the vehicle is provided with the roll angle calculating means for calculating the angle, it is not necessary to provide the lateral G sensor separately in the vehicle having the left and right wheel speed detecting means, so that the system cost can be reduced. The effect of becoming

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a claim showing an input acceleration calculation device for a vehicle according to the present invention.

FIG. 2 is a structural explanatory view showing a vehicle suspension device to which the input acceleration calculation device for a vehicle according to the first embodiment of the present invention is applied.

FIG. 3 is a system block diagram showing a vehicle suspension device to which the vehicle input acceleration computing device of the first embodiment is applied.

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 characteristic diagram of damping force characteristics 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 -L cross section and a MM cross section.

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 in the device of the first embodiment.

FIG. 15 is a time chart showing a phase relationship between lateral acceleration and roll angle.

FIG. 16 is a vector diagram for deriving an arithmetic expression for obtaining values of pure sprung vertical acceleration and lateral acceleration in the device of the first embodiment.

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

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

FIG. 19 is a plan view for explaining a mounting position of a lateral G sensor in the second embodiment device.

FIG. 20 is a roll angle characteristic diagram with respect to lateral acceleration in the apparatus of the second embodiment.

FIG. 21 is a lateral acceleration characteristic diagram with respect to the roll angle in the second embodiment device.

FIG. 22 is a structural explanatory view showing a vehicle suspension device to which the input acceleration calculation device for a vehicle according to the third embodiment of the present invention is applied.

FIG. 23 is a system block diagram showing a vehicle suspension device to which the vehicle input acceleration calculation device of the third embodiment is applied.

FIG. 24 is a block diagram showing a signal processing circuit in the device of the third embodiment.

FIG. 25 is actual measurement data showing the relationship between the left-right wheel speed difference and the roll angle in the third embodiment device.

[Explanation of symbols]

 a sprung vertical acceleration detecting means b lateral acceleration detecting means c roll angle detecting means d input acceleration calculating means

Claims (4)

[Claims] 1. A sprung vertical acceleration detecting means for detecting sprung vertical acceleration at a predetermined position in a vehicle, a lateral acceleration detecting means for detecting lateral acceleration of the vehicle, and a roll angle detecting means for detecting a roll angle of the vehicle. And a roll vector of the vehicle based on the combined vector of the sprung vertical acceleration detected by the sprung vertical acceleration detecting means and the lateral acceleration detected by the lateral acceleration detecting means, and the roll angle detected by the roll angle detecting means. An input acceleration calculation device for a vehicle, comprising: input acceleration calculation means for calculating a pure sprung vertical acceleration of the vehicle and / or a pure lateral acceleration of the vehicle that does not include a detection error. 2. The lateral acceleration detecting means comprises left and right wheel speed difference detecting means for detecting a rotational speed difference between the left and right wheels, and lateral acceleration calculating means for calculating a lateral acceleration of the vehicle from the rotational speed difference between the left and right wheels. The input acceleration calculation device for a vehicle according to claim 1, wherein 3. The roll angle detecting means comprises left and right wheel speed difference detecting means for detecting a rotational speed difference between the left and right wheels and roll angle calculating means for calculating a roll angle of the vehicle from the rotational speed difference between the left and right wheels. The input acceleration calculation device for a vehicle according to claim 1 or 2, wherein: 4. The lateral acceleration detecting means comprises a lateral acceleration sensor provided on the spring of the vehicle, and the roll angle detecting means determines the vehicle roll angle from the lateral acceleration of the vehicle detected by the lateral acceleration sensor. The input acceleration calculation device for a vehicle according to claim 1, wherein the input acceleration calculation device comprises a roll angle calculation means for calculation.