JP3411429B2 - Loading status judgment 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 loading state determination device for detecting a load state change state in a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a loading state determination device for controlling a damping force characteristic of a shock absorber, for example, one disclosed in Japanese Patent Publication No. 4-500490 is known.

This conventional loading state determination device detects a dynamic vehicle running state by a sensor, forms a control signal for controlling a semi-active shock absorber provided on each wheel of the vehicle, and outputs the control signal as a control signal. The vehicle body was controlled according to the actual value of the damping force.

[0004]

However, the conventional device has the following problems because it does not consider the change of the loading state in the vehicle.

That is, in this conventional apparatus, the damping of the shock absorber at each wheel is considered in consideration of a constant loading state, that is, the vehicle weight and the wheel load acting on each wheel, and the wheel load balance between the front wheels and the rear wheels. Although the control gain is set to perform force characteristic control, if the vehicle weight and the wheel load balance between the front and rear wheels have changed from the design state, the control gain for the running state of the vehicle May not be appropriate, and optimal ride comfort and steering stability may not be obtained.

By using a vehicle height sensor separately, it is possible to detect a change in the loading state based on a change in vehicle height in the vehicle, but another problem of increased cost arises.

The present invention has been made by paying attention to the above-mentioned conventional problems, and without providing a separate vehicle height sensor,
An object of the present invention is to provide a loading state determination device capable of accurately detecting a change in loading state of a vehicle from two vehicle up and down state amounts detected in the vehicle up and down direction detected by the vehicle up and down state amount detecting means. Is.

[0008]

In order to achieve the above-mentioned object, the loading state judging device according to claim 1 of the present invention is shown in FIG.
As shown in the claim correspondence diagram of FIG. 1, a pair of front and rear vehicle up and down state quantity detecting means a1 and a2 are provided with a predetermined distance in at least the front and rear direction of the vehicle to detect the up and down state quantity of the vehicle. And the up-and-down state quantity of the vehicle detected by the pair of up-and-down state quantity detecting means a1 and a2 of the vehicle in the up-and-down direction , the sprung mass behavior with respect to the road surface input frequency is determined.
Larger when comparing the bell with standard loading and full loading
Frequency that extracts high frequency components that appear as a level difference
Extracted by the component extraction means d and the high frequency component extraction means d
High-frequency components in the vertical direction on the front wheel side and on the rear wheel side
The loading amount determination signal detecting means b for detecting the loading amount determination signal of the vehicle based on the ratio of the downward state amount high frequency component, and the loading amount determination signal of the vehicle detected by the loading amount determination signal detecting part b make a predetermined determination. The load amount change judging means c for calculating the ratio exceeding the predetermined threshold value within the time and judging the load amount change state of the vehicle based on the ratio is used. Here, the vehicle up-and-down state quantity is the vehicle top on the spring.
State quantity including downward behavior, such as sprung vertical velocity
Degree, sprung vertical acceleration, sprung unsprung relative speed, spring
The relative acceleration between the upper and lower springs.

According to a second aspect of the present invention, there is provided a loading state determination device, wherein the pair of front and rear vehicle vertical direction state amount detecting means a1,
The vertical state quantity detected in a2 is the vehicle vertical state quantity amplitude. The front-back weight ratio change state in the vehicle is detected from the front- back amplitude ratio by comparing the vehicle vertical direction state quantity amplitudes at the two front and rear sides. The change ratio of the weight ratio is used as the vehicle load determination signal detected by the load determination signal detection means c.

According to a third aspect of the present invention, there is provided a loading state determination device, wherein the pair of front and rear vehicle vertical direction state quantity detecting means a ₁ ,
The vertical state quantity detected in a ₂ is the vehicle vertical state quantity amplitude, and the center of gravity position change state of the vehicle is detected from the vehicle vertical direction state quantity amplitudes at the two front and rear locations, and the center of gravity position change state is detected by the loading state. This is used as a vehicle load determination signal detected by the load determination signal detecting means c.

According to a fourth aspect of the present invention, there is provided a loading state determination device, wherein a vehicle at the rear of the vehicle is determined based on a predetermined transfer function from the vehicle vertical state quantity at the front detected by the vehicle vertical state quantity detecting means a ₁ at the front. In addition to estimating the vertical state quantity,
The estimated value and the vehicle vertical direction state quantity detection means a _{2 at the} rear side
A comparison value with the rear vehicle up-down direction state amount actually detected in (1) is obtained, and the comparison value is used as the vehicle loading amount determination signal detected by the loading amount determination signal detecting means c.

According to a fifth aspect of the present invention, there is provided a loading state determination device, wherein the pair of front and rear vehicle vertical direction state quantity detecting means a ₁ ,
while calculating a distance from the reference position than the vehicle vertical direction state amount before and after the two locations is detected by a ₂ to instantaneous rotation center of the body, seeking a moving average value of the distance from the reference position to the instantaneous center of rotation of the body The moving average value is used as a vehicle load determination signal detected by the load determination signal detecting means c.

According to a sixth aspect of the present invention, there is provided the loading state determination device, wherein the pair of front and rear vehicle vertical state quantity detecting means a ₁ ,
Amount of change in both positive and negative peak values is obtained from the vehicle up-and-down state quantity at two locations before and after detected in a ₂ , and
A comparison value of the change amounts of both the positive and negative peak values at the two front and rear positions is obtained, and the comparison value is used as the vehicle load determination signal detected by the load determination signal detection means c.

According to a seventh aspect of the present invention, the loading state determination device uses the vehicle vertical direction state amount detected by the vehicle vertical direction state amount detecting means a ₁ and a ₂ as a sprung vertical velocity of the vehicle. is there.

Further, in the loading state determination device according to the present invention, the vehicle vertical direction state amount detected by the vehicle vertical direction state amount detecting means a ₁ and a ₂ is used as the sprung vertical acceleration of the vehicle. is there.

According to a ninth aspect of the present invention, in the loading state determination device, the vehicle vertical direction state amount detected by the vehicle vertical direction state amount detecting means a ₁ and a ₂ is defined as a relative speed between unsprung and unsprung portions of the vehicle. It was done.

According to a tenth aspect of the present invention, the vehicle vertical direction state quantity detected by the vehicle vertical direction state quantity detecting means a ₁ and a ₂ is defined as the relative acceleration between the sprung and unsprung portions of the vehicle. It was done.

[0018]

In the loading state determination device according to claim 1 of the present invention,
As described above, the vertical state quantity of the vehicle is detected at both front and rear detection positions having a predetermined distance at least in the front and rear direction of the vehicle , and the high frequency component extracting means is detected from the vehicle vertical state quantities at the two front and rear locations. At the road surface input frequency
The level of sprung mass behavior with respect to the number at standard loading and full loading
High level that appears as a large level difference when compared with time
Frequency components are extracted, and the vertical direction of the extracted front wheels
High frequency component of the state quantity
The vehicle load determination signal is detected based on the ratio .

And, the occupant of the vehicle is only one driver,
Also, looking at the load capacity determination signal when the vehicle is running in the minimum load capacity state where the luggage load in the trunk room is 0 and the load capacity determination signal when the vehicle is loaded with a large amount of luggage in the trunk room, A distinguishable difference occurs in the load determination signal level depending on the amount. This is because when loading luggage in the luggage compartment, the ratio of the load acting on the rear wheel side to the front wheel side increases, and as a result, the variation in the vehicle vertical state quantity also differs between the front and rear of the vehicle. The same thing happens when a person gets on the rear seat side.

Therefore, the ratio of the load amount judgment signal exceeding a predetermined threshold value within a predetermined judgment time is calculated,
By observing the magnitude of the ratio, it is possible to accurately determine the load state change state of the vehicle even with an unstable load amount determination signal that fluctuates according to the movement of the occupant in the vehicle and the road surface condition.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 2 is a structural explanatory view showing a loading state determination device to which the loading state determination device according to the first embodiment of the present invention is applied, which is interposed between a vehicle body and four wheels. Four
Shock absorbers SA _FL , SA _FR , SA _RL , SA
_RR (In the explanation of the shock absorber, when referring to these four collectively, and when describing the common configuration of these, it is simply indicated as SA. Also, the lower right symbol indicates the wheel position. , _FL indicates the front wheel left, _FR indicates the front wheel right, _RL indicates the rear wheel left, and _RR indicates the rear wheel right.). A vertical acceleration sensor (hereinafter referred to as a vertical acceleration sensor) for detecting a vertical acceleration G is provided on the vehicle body at a position (tower position) near the front wheel left and right shock absorbers SA _FL and SA _FR and the rear wheel left and right shock absorbers SA _RL and SA _RR. , Up and down G sensor) 1 _FL , 1 _FR , 1 _RL ,
1 _RR is provided, also, a vehicle speed sensor 2 is not shown for detecting a vehicle speed of the vehicle, the door sensor 5, the ignition switch 6 is provided, furthermore, in the vicinity of the driver's seat, the vertical G sensors 1 (1 _FL , 1 _FR , 1 _RL , 1 _RR ),
A control unit 4 is provided which inputs signals from the vehicle speed sensor 2, the door sensor 5, and the ignition switch 6 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

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 _FL. , 1 _FR , 1 _RL , 1 _RR sprung vertical acceleration G _FL ,
G _FR , G _RL , G _RR signals and the vehicle speed Sv from the vehicle speed sensor 2
The signal, the open / close signal from the door open sensor 5, and the ON / OFF signal from the ignition switch 6 are input. As shown in FIG. 14, the interface circuit 4a has sprung vertical accelerations G _FL , G _FR ,
The sprung vertical velocity Δx at each tower position from the G _RL and G _RR signals
_FL , Δx _FR , Δx _RL , Δx _RR and sprung-unsprung relative speed (Δx−Δx ₀ ) _FL , (Δx−Δx ₀ ) _FR , (Δ
x-Δx _{0) RL,} (a signal processing circuit for obtaining the Δx-Δx _{0) RR,} as shown in FIG. 18, for determining the loading state determination signal R _M used in the payload of the change state determination in the vehicle Signal processing circuit. In addition,
Details of both signal processing circuits will be described later.

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 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. 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, a hollow portion 19 is formed, a first lateral hole 24 and a second lateral 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 the 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 with 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 section, the LL section and the MM section, and the NN section in FIG. 8, FIG. 9, and FIG. 10, and the damping force characteristics at each position are shown in FIGS.

Next, in the control operation of the control unit 4, the configuration of the signal processing circuit for obtaining the sprung vertical velocity Δx and the sprung-sprung relative velocity (Δx-Δx ₀ ) is shown in the block diagram of FIG. It will be described with reference to the drawings.

First, in B1, the phase delay compensation formula is used,
Each vertical G sensors _{1 (1 FL, 1 FR,} 1 RL, 1 RR) on each spring is detected by the vertical acceleration _{G (G FL, G FR,} G RL, G RR)
Is converted into a sprung vertical velocity signal at each tower position.

The general equation for phase delay compensation can be expressed by the following transfer function equation (1). G _(S) = (AS + 1) / (BS + 1) ... (1) (A <B) And the frequency band (0.5 Hz to 3) required for damping force characteristic control.
Has the same phase and gain characteristics as the case of integrating (1 / S) at (Hz), and the following transfer function formula (2) is used as a phase delay compensation formula for lowering the gain on the low frequency side (up to 0.05 Hz). ) Is used.

G _(S) = (0.001 S + 1) / (10S + 1) × γ (2) Note that γ is a signal and a gain characteristic when speed is converted by integration (1 / S). Is a gain for matching, and in this embodiment, γ = 10 is set. as a result,
The gain characteristic of the solid line in (a) of FIG. 15 and FIG.
As shown in the solid line phase characteristic in (b) of 5, the state where only the low frequency side gain is reduced without deteriorating the phase characteristic in the frequency band (0.5 Hz to 3 Hz) required for damping force characteristic control. Becomes The dotted lines (a) and (b) in FIG. 15 indicate the gain characteristic and phase characteristic of the sprung vertical velocity signal whose velocity is converted by integration (1 / S).

At B2, a bandpass filter process for cutting off components other than the target frequency band to be controlled is performed. That is, this bandpass filter BPF is composed of a secondary high-pass filter HPF (0.3 Hz) and a secondary low-pass filter LPF (4 Hz), and has a sprung vertical velocity targeting the sprung resonance frequency band of the vehicle. Δx (Δx _FL ,
Δx _FR , Δx _RL , Δx _RR ) signals are obtained.

On the other hand, at B3, as shown in the following equation (3),
The vertical acceleration G (G _FL , G _FR , G _RL , G _{RR )} detected by each vertical G sensor 1 using the transfer function Gu _(S) from each sprung vertical acceleration to the relative speed between the sprung and unsprung _portions. ) Signal, the relative speed (Δx
−Δx ₀ ) [(Δx−Δx ₀ ) _FL , (Δx−Δx
₀ ) _FR , (Δx−Δx ₀ ) _RL , (Δx−Δx ₀ ) _RR ] signals are obtained. Gu _(S) =-ms / (cs + k) (3) As shown in the one-wheel model of FIG. 19, m is the sprung mass, c is the damping coefficient of the suspension, and k is the suspension. Is a spring constant, and s is a Laplace operator.

Next, the content of the damping force characteristic control operation of the shock absorber SA in the control unit 4 will be described with reference to the flowchart of FIG. In addition,
This basic control is performed by each shock absorber SA _FL , SA _FR ,
This is performed for each SA _RL and SA _RR .

In step 101, the sprung vertical velocity Δx
Is a positive value. If YES, the process proceeds to step 102 to control each shock absorber SA to the extension side hard region HS, and if NO, the process proceeds to step 103.

In step 103, the sprung vertical velocity Δx
Is a negative value, and if YES, the routine proceeds to step 104, where each shock absorber SA is controlled to the pressure side hard region SH, and if NO, the routine proceeds to step 105.

Step 105 is a processing step when it is judged NO in steps 101 and 103, that is, when the value of the sprung vertical velocity Δx is 0.
At this time, set each shock absorber SA to the soft area SS.
To control.

Next, the operation of damping force characteristic control will be described with reference to the time chart of FIG. The sprung vertical velocity Δx is
When changing as shown in this figure, as shown in the figure, when the value of the sprung vertical velocity Δx is 0, the shock absorber SA is controlled to the soft region SS.

When the sprung vertical velocity Δx has a positive value, the expansion side hard region HS is controlled to fix the compression side damping force characteristic to the soft characteristic, while the expansion side damping force characteristic (target). The damping force characteristic position P _T ) is changed in proportion to the sprung vertical velocity Δx based on the following equation (4).

P _T = α · Δx · K · δ (4) where α is a constant on the extension side and K is sprung-unsprung Gain that is variably set according to the relative speed (Δx−Δx ₀ ),
δ is a control gain that is variably set according to a change in the load on the vehicle, and the details of the variable setting control of the control gain δ will be described later.

When the value of the sprung vertical velocity Δx becomes a negative value, the compression side hard region SH is controlled to fix the extension side damping force characteristic to the soft characteristic, while the compression side damping force characteristic (target damping force The characteristic position P _C ) is calculated based on the following equation (5).
It is changed in proportion to the sprung vertical speed Δx. P _C = β · Δx · K · δ (5) Note that β is a constant on the pressure side.

Next, of the damping force characteristic control operation of the control unit 4, the switching operation state of the control area of the shock absorber SA will be mainly described with reference to the time chart of FIG.

In the time chart of FIG. 17, area a
Indicates that the sprung vertical velocity Δx is reversed from a negative value (downward) to a positive value (upward). At this time, the relative velocity (Δx−Δx ₀ ) is still negative (shock absorber SA).
Since the stroke is on the pressure stroke side), at this time, the shock absorber SA is controlled to the extension side hard area HS based on the direction of the sprung vertical velocity Δx.
Therefore, in this area, the shock absorber SA at that time
The pressure stroke side, which is the stroke of, has soft characteristics.

In the region b, the sprung vertical velocity Δx remains a positive value (upward) and the sprung-sprung relative velocity (Δx-Δx ₀ ) changes from a negative value to a positive value (shock absorber). Since the stroke of SA is the area switched to the extension side), at this time, the shock absorber SA is controlled to the extension side hard area HS based on the direction of the sprung vertical velocity Δx, and the shock absorber SA is also controlled. Is also an extension stroke, and therefore, in this region, the extension side which is the stroke of the shock absorber SA at that time has a hard characteristic proportional to the value of the sprung vertical velocity Δx.

In region c, the sprung vertical velocity Δx is reversed from a positive value (upward) to a negative value (downward), but at this time, the sprung-unsprung relative velocity (Δx) is still.
-Δx ₀ ) is a positive value area (the stroke of the shock absorber SA is the extension stroke side), and at this time, the shock absorber SA is in the compression side hard area SH based on the direction of the sprung vertical velocity Δx. Is controlled by
In this region, the extension side, which is the stroke of the shock absorber SA at that time, has soft characteristics.

In the region d, the sprung vertical velocity Δx remains a negative value (downward), and the sprung-unsprung relative velocity (Δx-Δx ₀ ) changes from a positive value to a negative value (shock absorber). Since the stroke of SA is on the extension side), at this time, the shock absorber SA is controlled to the compression side hard region SH based on the direction of the sprung vertical velocity Δx, and the stroke of the shock absorber is also It is a pressure stroke,
Therefore, in this area, the shock absorber SA at that time
The pressure stroke side, which is the stroke of, has a hard characteristic proportional to the value of the sprung vertical velocity Δx.

As described above, in this embodiment, the sprung vertical velocity Δx and the sprung-unsprung relative velocity (Δx-Δ
x ₀ ) has the same sign (area b, area d), the stroke side of the shock absorber SA at that time is controlled to a hardware characteristic, and when it has a different sign (area a, area c), it is the shock absorber at that time. The same control as the damping force characteristic control based on the skyhook control theory of controlling the stroke side of SA to the soft characteristic is performed based on only the sprung vertical velocity Δx signal. Further, in this embodiment, when the stroke of the shock absorber SA is changed, that is, when the area a is changed to the area b and the area c is changed to the area d (soft characteristic to hard characteristic), the stroke is changed. The damping force characteristic position on the side is the previous area a,
Since the switching to the hardware characteristic side has already been performed in c, the switching from the soft characteristic to the hardware characteristic can be performed without a time delay, and thus high control response can be obtained and the hardware characteristic to the soft characteristic can be obtained. Switching to the pulse motor 3 is performed without driving the pulse motor 3, which improves the durability of the pulse motor 3 and
Power consumption will be saved.

Next, of the control operation of the control unit 4, the contents of the variable setting control of the control gain δ based on the change of the loading amount in the vehicle will be described. First, the configuration of the signal processing circuit for obtaining the loading state determination signal R _M used for determining the loading state change state will be described with reference to the block diagram of FIG.

First, in C1, the average of the front and rear spring sprung vertical accelerations G _FL and G _FR signals detected by the front and rear left and right upper and lower G sensors 1 _FL and 1 _FR is used to determine the sprung up and down at the center position of the front wheel. calculated acceleration GFS other hand, in C5, the rear-wheel-side left and right vertical G sensors 1 _RL, 1 on wheel left and right spring after being detected by the _RR vertical acceleration G _RL, from the average value of G _RR signal, the rear wheel side central Determine the sprung vertical acceleration GRS of the position.

In the subsequent C2, C6 (high frequency component extraction means) , two steps for extracting the high frequency components GFS-H, GRS-H of the sprung vertical accelerations GFS, GRS at the front wheel side central position or the rear wheel side central position. Band pass filters BPF1, BPF
Two processes are performed respectively. That is, in this bandpass filter process, the secondary bandpass filters BPF1 and BPF2 having a cutoff frequency of 3 Hz are used.

Then, both filters BPF1 and BPF
As No. 2, as shown in the gain characteristic diagram with respect to the frequency in FIG. 20, a small damping value (Q = 5) is used to emphasize the target gain of the 3 Hz portion.

In the subsequent C3 and C7, the high frequency component GFS
_-H , GRS _-H low-frequency processed signal GFS indicating the fluctuation state of the amplitude between the positive peak value and the negative peak value
_-L , GRS _-L is requested. That is, as shown in (a) of FIG. 21, the peak values on the plus side and the minus side of the high frequency components GFS- _H and GRS- _H are detected and stored, respectively.
When the next peak value is detected, the peak value is sequentially updated. Then, each time the plus or minus side peak value is detected, the minus side peak value is subtracted from the plus side peak value, and the value is stored in memory.
The low-frequency processed signals GFS- _L and GRS- _L as shown in (b) of 1 are obtained.

In subsequent C4 and C8, the low-frequency processed signals GFS- _L and GRS- _L are processed by a low-pass filter LPF having a cutoff frequency of 0.05 Hz to obtain a moving-averaged low-frequency processed signal Af, Ar is obtained.

Finally, in C9, both low frequency processed signals A are
From f and Ar, a loading state determination signal R _M corresponding to the amplitude ratio of both sprung vertical acceleration signals at the vehicle front-rear position is obtained based on the following equation (6). _{R M = Af / Ar ·············· (} 6) That is, the signal processing circuit of FIG. 18 constitutes a payload determination signal detection means the claims.

From the amplitude ratio of the sprung vertical acceleration signals (loading state determination signal R _M ) at the vehicle front-rear position thus obtained, the front-rear weight ratio of the rear wheel center position to the front wheel center position of the vehicle is simplified. The reason will be described below.

In the one-wheel model shown in FIG.
x is a sprung mass, m is a sprung mass, k is a spring constant of the suspension, c is a damping coefficient of the suspension, and u is a road surface input. In the model of FIG. 19, considering the behavior of the vehicle, the transmissibility x /
u is as shown in FIG.

FIG. 22A shows the sprung transmissivity characteristic with respect to the road surface input frequency on the front wheel side, and FIG.
Shows the sprung transmissivity characteristic for the road surface input frequency on the rear wheel side.In both figures, the solid line shows the transmissivity characteristic during standard loading, and the dotted line shows the transmissivity characteristic during full loading. Is.

As is clear from both of these characteristic diagrams, when the sprung transmission rate, that is, the level of sprung behavior is compared between standard loading and full loading, as shown in FIG. 22 (a) on the front wheel side. Although the level change is small, the rear wheel side shows a large level difference as shown in (b) of FIG. Especially when looking at the road surface input frequency, the standard loading (solid line) is high on the high frequency side of 2 Hz or more and full loading (dotted line)
A level difference occurs in the direction of decreasing, and the level difference appears to be the largest especially near 3 Hz.

Therefore, if, for example, a 3 Hz component of the sprung mass x is extracted, if the sprung mass m increases, the transmissivity (x / u) decreases, and the sprung mass m decreases. Then, the relationship is that the transmissibility (x / u) increases. If the front wheel side road surface input uf and the rear wheel side road surface input ur are the same, the load ratio (mr / mf) ≈ (xf / uf) / (xr / ur
) = Xf / xr.

The large level fluctuation at 3 Hz in (b) of FIG. 22 is the low frequency processed signal Ar on the rear wheel side, and the small level fluctuation on the front wheel side of (a) in FIG. Corresponds to the low-frequency processed signal Af on the front wheel side, and accordingly, the loading state determination signal R _M (= Af /
The value of Ar) will change in proportion to changes in the vehicle load.

Therefore, the front-rear weight ratio of the front wheel side weight and the rear wheel side weight of the vehicle is the amplitude ratio of the front wheel side sprung vertical acceleration and the rear wheel side sprung vertical acceleration (loading state determination signal R
Can be determined in a simplified manner in _M) (weight ratio ≒ amplitude ratio).

Incidentally, (b) of FIG. 24 is a time chart showing the changing state of the loading state judgment signal R _M , and in this figure, in the time zone (I), the occupant of the vehicle is one driver, Moreover, while the load state determination signal R _M when the vehicle is running in the minimum load state where the loaded luggage in the trunk room is 0 is shown, the time zone (II) is full of five occupants. The figure shows the variation state of the loading state determination signal R _M when traveling in the loading state, and it can be seen that the level of the loading state determination signal R _M has a distinguishable difference depending on the number of occupants (loading amount).

This is a phenomenon that occurs when three persons are seated in the rear seat and the ratio of the load acting on the rear wheel side to the front wheel side increases, and the same thing occurs when a large amount of luggage is loaded in the luggage compartment. Also occurs in.

[0065] Therefore, as shown in FIG. 24, to set the payload decision threshold R _ML, by looking at the variation state of the loading state determination signal R _M the payload decision threshold R _ML basis, It is possible to detect the fluctuation state of the loading amount in the vehicle. That is, the flow chart portion of FIG. 23 for performing the above operation constitutes the load amount change judging means in the claims.

Below, the target damping force characteristic positions P _T , P
_{In the} above equations (4) and (5) for obtaining _C , the contents of the variable setting control operation of the control gain δ that is variably set according to the change in the load amount will be described based on the flowchart of FIG. 23 and the time chart of FIG. To do.

First, in the flow chart of FIG.
In step 201, it is determined whether or not the determination permission flag is set to ON, and if YES, the process proceeds to step 202. The initial value of the determination permission flag is set to the ON state.

In step 202, the vehicle speed Sv of the vehicle is
Is greater than or equal to a predetermined threshold value V _L , YE
When S (Sv ≧ V _L ), the routine proceeds to step 203,
After adding 1 to the timer count n, step 204
Proceed to.

In step 204, the timer count n is the predetermined delay time count Ns (= 40 = 20 sec).
If YES (n ≧ Ns), it is determined in step 20 to start the ratio measurement count.
Go to 5.

In step 205, it is determined whether or not the loading state determination signal R _M is equal to or greater than a predetermined loading amount determination threshold value R _ML . If YES, the process proceeds to step 206 and the ratio measurement count Nc After adding 1 to, proceed to step 208. If NO, step 20
Proceed to step 7 to set the ratio measurement count Nc to the previous count Nc.
In step S208, the process proceeds to step 208.

In this step 208, it is judged whether or not the timer count n is the measured time count N _E (= 140 = 50 sec) or more, and if YES (n ≧ N _E ),
Go to step 209.

In this step 209, it is judged whether or not the ratio measurement count Nc is a predetermined ratio value N _R (= 70) or more, and if NO (Nc ≤N _R ), the step 21
0, and if YES (Nc> N _R ), proceed to step 212.

In step 210, it is determined whether or not the load amount determination flag is reset to 0. If the flag is NO, the process proceeds to step 211, and after the following normal load control processing is performed, Ends the control flow once.

The loading amount determination flag is reset to zero. Reset the judgment permission flag to OFF. Set to the normal loading control gain δ _M. If YES (loading amount determination flag = 0),
Since it is not necessary to repeat the process of step 211, this ends one control flow.

In step 212, it is determined whether the loading amount determination flag is set to 1, and N
When it is O, the routine proceeds to step 213, and after the following large-load control processing, the one control flow is ended. Set the payload judgment flag to 1. Reset the judgment permission flag to OFF. Set the control gain δ _H (> δ _M ) during heavy loading. If YES (loading amount determination flag = 1),
Since it is not necessary to repeat the process of step 211, this ends one control flow.

If NO (determination permission flag = 0FF) in step 201, step 21
Go to 4. Then, in this step 214, it is determined whether or not one of the following states has occurred. The signal from the ignition switch 6 is off. The signal from the door sensor 5 is open. If YES, the load may change. Therefore, the process proceeds to step 215, the judgment permission flag is set to 0N, and then the process proceeds to step 216. If NO, the load is changed. Since there is no possibility of fluctuation, the process proceeds directly to step 216. In this step 216, the timer count n and the ratio measurement count Nc are reset to 0, and then one control flow ends.

In step 202, NO (Sv ≤
If it is determined to be V _L ), the process proceeds to step 216. Further, in steps 204 and 208, NO (n <Ns, n
If it is determined to be <N _E ), this ends one control flow.

Next, the target damping force characteristic positions P _T , P
The contents of the variable setting control operation of the control gain δ that is variably set according to the change in the load amount in the above equations (4) and (5) for obtaining _C will be described based on the time chart of FIG.

(A) Small load capacity When the vehicle occupant is the only driver and the luggage load in the luggage compartment is 0, the time is as shown in the time chart of FIG. 24 (b). As shown in the band (I), the level of the load amount determination signal R _M (≈weight ratio) is low and is equal to or lower than the load amount determination threshold value R _ML .

Therefore, when the vehicle speed Sv of the vehicle becomes equal to or higher than the predetermined threshold value V _L , the timer starts counting, and the timer count n is the predetermined delay time count Ns (20 sec).
The predetermined measurement time count N _E (50
sec)), the ratio measurement count Nc, which is the number of times the load amount determination signal R _M is equal to or higher than the load amount determination threshold value R _{ML, is} less than or equal to a predetermined ratio value N _R (70). Therefore, at this time, the normal loading control process is performed in step 211.

That is, the target damping force characteristic positions P _T , P
The control gain δ in the above equations (4) and (5) for obtaining _C is the state that is set to the normal loading control gain δ _M , which allows the calculation based on the skyhook control theory at a small loading amount. The optimum damping force characteristic control is performed, and the riding comfort and steering stability of the vehicle can be secured. (B) When the vehicle has a large load When the vehicle starts to run with five passengers fully loaded (or with a large amount of luggage loaded in the luggage compartment), time zone (II) in the time chart of Figure 24 (b) As shown in, the level of the load amount determination signal R _M (≈weight ratio) becomes high, and the ratio of the time when the load amount determination threshold value R _ML is exceeded increases, so that the load amount determination signal R _M becomes Since the ratio measurement count Nc, which is the number of times of control that is equal to or greater than the load amount determination threshold value R _ML, exceeds a predetermined ratio value N _R (70), at this time, the large load control process is performed in step 213. Be done.

That is, the target damping force characteristic positions P _T , P
The formula for obtaining the _C (4), the control gain [delta] is in the (5), the normally variably set on the loading time of the control gain [delta] Large stack when control gain higher than _M [delta] _H, thereby, compared to the time of a small load capacity, The target damping force characteristic positions P _T and P _C are set higher. In this case, since becomes large increase in the weight of the rear wheel side from the front side, the value of a large load when the control gain [delta] _H is set higher is better for the rear wheels than the front wheel side.

After the control gain δ is once switched, the ignition is turned off at least thereafter.
It will continue until the door is opened or the door is opened. Therefore, it is possible to prevent the deterioration of the riding comfort and the steering stability of the vehicle due to the increase of the loading amount by the high damping force characteristic which is automatically and variably set.

As described above, the loading state determination device according to the first embodiment has the following effects. Without separately providing a vehicle height sensor, it is possible to detect a change in the loading state of the vehicle from the sprung vertical acceleration signals at two positions in the vehicle front-rear direction, which are obtained from the sprung vertical acceleration signals detected by the vertical G sensors 1. Therefore, the cost can be reduced.

The ratio at which the load amount judgment signal R _M exceeds the predetermined load amount judgment threshold value R _ML within a predetermined judgment time (measurement time count N _E ) is calculated, and the calculated ratio (ratio measurement count Nc) is calculated. By comparing the magnitude with the predetermined ratio value N _R , even if the unstable loading amount determination signal R _M that fluctuates according to the movement of the occupant in the vehicle and the road surface condition, the loading amount change state of the vehicle can be accurately determined. You can judge.

As a means for converting the sprung vertical acceleration to the sprung vertical velocity, the phase lag compensation formula is used to prevent signal drift due to extra low frequency signal input, such as during braking. As a result, it becomes possible to prevent the controllability of the damping force characteristic of the shock absorber SA from deteriorating and ensure the riding comfort of the vehicle.

Since switching from the soft characteristic to the hard characteristic is performed without a time delay, a high control response is obtained, and the switching from the hard characteristic to the soft characteristic is performed without driving the actuator. This makes it possible to improve the durability of the actuator and save power consumption.

Next, another embodiment of the present invention will be described. In the description of the other 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 different points will be described.

(Second Embodiment) This second embodiment differs from the first embodiment in the method of calculating a load amount determination signal for determining a change in the load amount. A method of calculating the quantity determination signal will be described.

FIG. 25 is a view for explaining the moving state of the position G of the center of gravity based on the variation of the loading amount in the vehicle.
As shown in this figure, the center of gravity G from the front tower position
The distance L to the position can be calculated by the following equation (7). In addition, mf is a sprung mass on the front wheel side, mr is a sprung mass on the rear wheel side, and Lw is a wheel base. L = (mr / (mf + mr)). Lw ... (7) Therefore, it can be approximated to the following formula 9 as in the case of the weight ratio.

[0091]

[Formula 9]

That is, in the first embodiment, as shown in FIG.
In the signal processing circuit of No. 8, the loading state determination signal R _M is obtained from the amplitude ratio (≈weight ratio) of the low-frequency processed signals Af and Ar on the front wheel side and the rear wheel side. The approximate value of the distance L (variation state of the center of gravity position) from the front wheel tower position to the center of gravity G position is obtained based on the following equation (8).

L≈ (Af / (Af + Ar)) ・ Lw ... (8) That is, the distance L from the front wheel tower position to the center of gravity G position L
Is the load amount determination signal R _M detected by the load amount determination signal detection means. Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained.

(Embodiment 3) Embodiments 1 and 2
However, while the control gain δ is variably controlled with respect to the variation of the loading state determination signal R _M based on the variation of the loading state, the control parameter is switched and controlled.
In the third embodiment, when the loading capacity of the vehicle changes, the sprung mass resonance frequency also changes the sprung mass resonance frequency of the vehicle. Bandpass filter B desired
The control parameters are switched by controlling the cutoff frequency of the PF (B2 in the block diagram of FIG. 14) in two stages according to the fluctuation of the sprung resonance frequency during normal loading and large loading as described below. It is designed to be controlled.

Normal loading: HPF (f _H = 0.3 Hz), LPF (f _L = 4 Hz) Large loading: HPF (f _H '= 0.2 Hz), LPF (f _L '= 3 Hz) FIG. 26 is a gain characteristic diagram with respect to the frequency of the bandpass filter BPF. The solid line shows the gain characteristic diagram of the bandpass filter BPF used during normal loading, and the dotted line shows It is a gain characteristic view of the band pass filter BPF used at the time of large loading. Therefore, also in the third embodiment, the same effect as in the first embodiment can be obtained.

Although the embodiment of the present invention has been described above, the specific structure is not limited to this embodiment, and the present invention is applicable even if there are design changes and the like within the scope not departing from the gist of the present invention. include.

For example, in the embodiment, as the vehicle up-down state quantity detected by the vehicle up-down state quantity detecting means,
The case of using the sprung vertical acceleration is shown, but in addition,
It is also possible to use the sprung vertical velocity, the sprung unsprung relative velocity, the sprung unsprung relative acceleration, and the like.

Further, in the embodiment, the switching of the control parameters is switched only in two stages of the normal loading and the large loading, but it is also possible to switch the control parameters in three or more stages.

Further, in the embodiment, the variable setting of the control gain is carried out for all the shock absorbers on the front wheel side and the rear wheel side, but it is also possible to set only one of the front wheel side or the rear wheel side.

In the embodiment, the soft area SS is controlled only when the sprung vertical speed signal is 0. However, a predetermined dead zone centered at 0 is provided and the sprung vertical range is set within this dead zone. Control hunting can be prevented by maintaining the damping force characteristic in the soft region SS while the speed changes.

Further, the rear vehicle up-down state quantity is estimated based on a predetermined transfer function from the front vehicle up-down state quantity detected by the front vehicle up-down state quantity detecting means, and the estimated value and the above A comparison value with the rear vehicle vertical direction state amount actually detected by the rear vehicle vertical direction state amount detection means is obtained, and the comparison value is detected by the load amount determination signal detection means. Can be

Further, the distance from the reference position to the instantaneous center of rotation of the vehicle body is calculated from the vehicle up-and-down state quantity at two front and rear positions detected by the pair of vehicle up-and-down state quantity detecting means, and from the reference position. A moving average value of the distance to the instantaneous center of rotation of the vehicle body may be obtained, and the moving average value may be used as the vehicle load determination signal detected by the load determination signal detection means.

Further, the amount of change in both the positive and negative peak values is obtained from the vehicle vertical direction state quantities at two front and rear positions detected by the pair of vehicle vertical direction state quantity detection means.
It is also possible to obtain a comparison value of the change amounts of both the positive and negative peak values at the two locations before and after the front and back, and use the comparison value as the vehicle load determination signal detected by the load determination signal detection means.

[0104]

As described above, the present invention claims 1.
As described above, in the vehicle suspension device described above, a pair of front and rear vehicle vertical state amount detection means that are provided at least in the front and rear direction of the vehicle with a predetermined distance to detect the vertical state state amount of each vehicle. And the vehicle up-and-down state quantity detected by the pair of vehicle up-and-down state quantity detecting means .
The level of sprung mass behavior with respect to the road surface input frequency
Large level difference when comparing loaded and full loaded
High-frequency component extractor that extracts high-frequency components that appear as
And the front wheel side extracted by the high-frequency component extracting means.
Vertical state quantity High frequency component and vertical state quantity on rear wheel side is high
The load amount determination signal detecting means for detecting the load amount determination signal of the vehicle based on the ratio with the frequency component, and the load amount determination signal of the vehicle detected by the load amount determination signal detection means are set within a predetermined determination time. By adopting a configuration including a load change determination means for calculating a ratio exceeding a threshold value and determining a load change state of the vehicle based on the ratio, a vehicle height sensor can be provided in the vehicle without a separate vehicle height sensor. Even when the load determination signal is unstable, which fluctuates according to the movement of the occupant or the road surface condition, the loading state of the vehicle is determined from the vehicle up-down direction state quantities of the vehicle front-back direction two locations detected by the vehicle up-down direction state quantity detection means. It is possible to obtain the effect that it becomes possible to accurately detect the change in

[Brief description of drawings]

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

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

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

FIG. 4 is a cross-sectional view showing a shock absorber applied to 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 -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 for obtaining a sprung vertical velocity and a sprung-unsprung relative velocity in the first embodiment.

FIG. 15 is a gain characteristic (a) and a phase characteristic of the sprung vertical velocity signal obtained by the signal processing circuit according to the first embodiment.
It is a figure which shows (b).

FIG. 16 is a flowchart showing the details of the damping force characteristic control operation of the control unit in the first embodiment.

FIG. 17 is a time chart mainly showing the content of the switching operation of the control area of the shock absorber in the damping force characteristic control operation of the control unit in the first embodiment.

FIG. 18 is a block diagram showing a signal processing circuit for obtaining a load amount determination signal in the first embodiment.

FIG. 19 is a one-wheel model diagram for deriving a transfer function expression from each sprung vertical acceleration to the sprung-unsprung relative velocity in the first embodiment.

FIG. 20 is a gain characteristic diagram with respect to frequency of the bandpass filter BPF used in the first embodiment.

FIG. 21 is a time chart for explaining how to obtain a low-frequency processed signal in the first embodiment.

FIG. 22 is a sprung mass transfer rate characteristic chart for road surface input on the front wheel side (a) and the rear wheel side (b).

FIG. 23 is a flowchart showing the details of the switching control operation of the damping force characteristic (control gain) based on the load variation in the first embodiment.

FIG. 24 is a time chart showing the details of the switching control operation of the damping force characteristic (control gain) based on the variation of the loading amount in the first embodiment.

FIG. 25 is an explanatory diagram for deriving an equation for obtaining the distance to the position of the center of gravity in the second embodiment.

FIG. 26 is a bandpass filter B according to the third embodiment.
It is a gain characteristic view with respect to the frequency of PF.

[Explanation of symbols]

a1 Vehicle up-down direction state quantity detecting means a2 Vehicle up-down direction state quantity detecting means b Loading amount judgment signal detecting means c Loading amount change judging means d High frequency component extracting means

Claims (10)

(57) [Claims] 1. A pair of front / rear vehicle vertical state quantity detecting means which are provided at least in the front / rear direction of the vehicle with a predetermined distance to detect the vertical state quantity of the vehicle, respectively. from both vertical state quantity of the vehicle detected by the vehicle vertical direction quantity of state detecting means, with respect to the road surface input frequency
Comparison of sprung behavior levels between standard loading and full loading
High frequency components that appear as a large level difference when
High-frequency component extracting means for extracting, and upper and lower sides of the front wheels extracted by the high-frequency component extracting means
Directional state quantity high frequency components and rear wheel side up and down state quantity high frequency components
The load amount determination signal detecting means for detecting the load amount determination signal of the vehicle based on the ratio to the load and the load amount determination signal of the vehicle detected by the load amount determination signal detection means have a predetermined threshold within a predetermined determination time. A loading state determination device comprising: a loading amount change determining unit that calculates a rate exceeding a value and determines a loading level variation state of a vehicle based on the rate. 2. The vertical state quantity detected by the pair of front and rear vehicle vertical state quantity detecting means is a vehicle vertical direction state quantity amplitude. Before and after comparing the vehicle vertical direction state quantity amplitudes at the two front and rear sides.
Detecting the front-rear weight ratio change state in the vehicle from the amplitude ratio ,
2. The loading state determination device according to claim 1, wherein the front-rear weight ratio change state is used as a vehicle loading amount determination signal detected by the loading amount determination signal detection means. 3. The vertical state quantity detected by the pair of front and rear vehicle vertical state quantity detecting means is a vehicle vertical direction state quantity amplitude, and the vehicle center of gravity position is determined from the vehicle vertical direction state quantity amplitudes at the two front and rear locations. 2. The load state determination device according to claim 1, wherein a change state is detected, and the change position of the center of gravity is used as a vehicle load determination signal detected by the load determination signal detection means. 4. A vehicle vertical state quantity at the rear of the vehicle is estimated based on a predetermined transfer function from the vehicle vertical state quantity of the front detected by the vehicle vertical state quantity detecting means at the front, and the estimated value is obtained. A comparison value with the rear vehicle vertical direction state amount actually detected by the rear vehicle vertical direction state amount detection means is obtained, and the comparison value is determined by the load amount determination signal detection means. The loading state determination device according to claim 1, wherein the device is a signal. 5. A distance from a reference position to an instantaneous center of rotation of a vehicle body is calculated from the vehicle vertical direction state quantities at two front and rear positions detected by the pair of front and rear vehicle vertical direction state quantity detecting means, and the reference position is calculated. 2. The moving average value of the distance from the vehicle to the instantaneous center of rotation of the vehicle body is obtained, and the moving average value is used as the vehicle load determination signal detected by the load determination signal detection means. Loading state determination device. 6. A vehicle vertical direction state quantity at two front and rear positions detected by the pair of front and rear vehicle vertical direction state quantity detecting means,
The amount of change in both the positive and negative peak values is obtained, and the comparison value of the amounts of change in both the positive and negative peak values at the two front and rear positions is obtained. The loading state determination device according to claim 1, wherein the determination signal is a determination signal. 7. The loading state determination device according to claim 1, wherein the vehicle vertical direction state quantity detected by the vehicle vertical direction state quantity detecting means is a sprung vertical speed of the vehicle. 8. The loading state determination device according to claim 1, wherein the vehicle vertical direction state amount detected by the vehicle vertical direction state amount detecting means is a sprung vertical acceleration of the vehicle. 9. The loading state determination device according to claim 1, wherein the vehicle up-down direction state amount detected by the vehicle up-down direction state amount detecting means is a relative speed between unsprung and unsprung portions of the vehicle. . 10. The loading state determination device according to claim 1, wherein the vehicle vertical direction state amount detected by the vehicle vertical direction state amount detecting means is a relative acceleration between sprung and unsprung portions of the vehicle. .