JP2574572Y2 - Vehicle suspension control device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for a vehicle, and more particularly to a technique for improving the roll characteristics of a vehicle.

[0002]

2. Description of the Related Art A typical vehicle suspension device is:
It is configured to combine a suspension spring and a shock absorber so that a predetermined spring action and a buffer action work.
In this case, the suspension characteristics are substantially constant. However, the required suspension characteristics vary depending on the operating conditions, and so-called active suspension devices have been proposed to meet this requirement (for example, Japanese Utility Model Laid-Open No. 3-118106 and Japanese Utility Model Laid-Open No. 3-12).
0207).

In this method, a wheel shaft is supported on a vehicle body via a hydraulic cylinder, and an actual stroke of the hydraulic cylinder is detected based on a relative displacement between the vehicle body and the wheel shaft, which changes according to a running state, and a target stroke is determined. The height of the vehicle is adjusted by controlling the flow rate of hydraulic oil supplied to the hydraulic cylinder to extend and retract the hydraulic cylinder so that they coincide with each other.

For example, when a vehicle body undergoes lateral acceleration or longitudinal acceleration during curve running or acceleration / deceleration, and this causes a change in posture such as rolling or pitching of the vehicle body, the change in posture is detected by a stroke sensor. In accordance with a deviation between the detected stroke value and a target stroke value calculated according to the acceleration / deceleration, the supply of the hydraulic oil to the hydraulic cylinder is controlled so that the actual stroke value matches the target value.

[0005]

By the way, the roll characteristic in the conventional active suspension system, that is, the setting of the roll angle according to the lateral acceleration, is such that the center of the roll is on the center line of the vehicle, in other words, the mass of the vehicle is It is set assuming that it is on the center line. For this reason, the forces applied to the left wheel side hydraulic cylinder and the right wheel side hydraulic cylinder according to the lateral acceleration at the time of turning are the same for the left and right, and the signs are different.

However, for example, in a large vehicle for transporting luggage, the load distribution is not necessarily symmetrical depending on the loaded state of the luggage and may be shifted to the left or right, and the roll center is always on the center line of the vehicle. Not necessarily. When the load distribution is deviated to the left or right as described above, the conventional device has a problem that a difference occurs in the roll angle between the left turn and the right turn.

[0007] The present invention has been made in view of the above circumstances, and even when the load distribution of the left and right wheels is different, such as in the case of single loading,
It is an object of the present invention to provide a vehicle suspension control device capable of giving the same roll angle for a left turn and a right turn.

[0008]

SUMMARY OF THE INVENTION For this reason, the present invention uses FIG.
As shown in the figure, a vehicle height adjusting means is interposed between the vehicle body and the axle, and a target of the vehicle height adjusting means which is set in advance according to an actual stroke and a traveling state in which a relative displacement between the vehicle body and the axle is detected. In a vehicle suspension control device configured to detect a deviation from a stroke and drive-control the vehicle height adjusting unit so as to match a target stroke, a relative displacement detecting unit that detects a relative displacement between a vehicle body and an axle; Lateral acceleration detecting means, right wheel load detecting means for detecting a load acting on the right wheel of the vehicle, left wheel load detecting means for detecting a load acting on the left wheel of the vehicle, and a detection value of both load detecting means. Calculating means for calculating the respective distances from the mounting positions of the respective vehicle height adjusting means on the right wheel side and the left wheel side to the roll center position; and the distances calculated by the calculating means and the detection values of the lateral acceleration detecting means. Target stroke calculating means for calculating each target stroke of each of the right and left wheel height adjusting means in accordance with the distance ratio based on the distance, and detecting relative displacement to each target stroke calculated by the target stroke calculating means. And control means for controlling driving of the right-wheel side and left-wheel side vehicle height adjusting means such that the respective detected strokes of the corresponding wheel side detected by the means coincide with each other.

[0009]

In this configuration, each load detecting means detects the load on the right wheel side and the load on the left wheel side. The calculating means calculates the distance from the suspension positions on both sides to the roll center position at this time based on the detected load. For example,
If the load of both wheels is equal, the distance to the roll center is equal, but if the load is different, the roll center shifts and the distance to the roll center is different. This makes it possible to determine whether the load is in a single-pile state. Then, the target stroke calculation means, based on the calculated distance to each roll center and the detected lateral acceleration,
The target strokes of the vehicle height adjustment means on the right wheel side and the left wheel side are calculated according to the ratio of the distance to the roll center, in other words, the distribution ratio of the load. The control means drives and controls each vehicle height adjusting means so that the actual stroke detected by the relative displacement detecting means coincides with the calculated target stroke.

As described above, by setting the respective target strokes on the right wheel side and the left wheel side in accordance with the loads acting on the right wheel and the left wheel, the same stroke is obtained regardless of the right turn and the left turn even when the load is loaded. The roll angle can be controlled to always have the same roll characteristics.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of the present embodiment, a wheel 1 is supported on a vehicle body 5 by a hydraulic cylinder 3 and an auxiliary spring 4 via an axle 2. The oil chamber 3a of the hydraulic cylinder 3 is connected via a flow control valve 6 to a hydraulic supply unit 7 composed of a pump, a tank and the like. The flow control valve 6
The amount of oil supply / discharge to / from the hydraulic cylinder 3 is controlled according to the output of the servo amplifier 8. The servo amplifier 8 compares an actual stroke from a stroke sensor 9 as a relative displacement detecting means, which is provided in parallel with the hydraulic cylinder 3 and detects relative displacement between the vehicle body and the axle, with a target stroke from a control unit 10 described later. A drive signal corresponding to the deviation is output to the flow control valve 6.

Other components except the control unit 10 and the hydraulic supply unit 7 are provided for each wheel. The control unit 10 detects the lateral acceleration of the vehicle from the lateral G sensor 11 and the right wheel load and the left wheel load from the right wheel load sensor 12 as right wheel load detecting means and the left wheel load sensor 13 as left wheel load detecting means, respectively. Each output is input, and based on these input values, the respective target strokes of the hydraulic cylinders 3 on the right wheel side and the left wheel side are calculated and output to the servo amplifier 8 as shown in the flowchart of FIG.

As shown in FIG. 2, the control unit 9 includes a lateral acceleration signal input means 21 for converting the output of the lateral G sensor 11 into a lateral acceleration signal and inputting the same, and a right wheel load sensor 12 and a left wheel load sensor 13. The right wheel load signal input means 22 and the left wheel load signal input means 23 for converting each output into respective load signals and inputting them, and the suspension mounting position of each wheel based on the output from both load input means 22 and 23 Distance calculating means 24 for calculating the distance to the roll center position, and according to the ratio of the distance from the roll center calculated based on the output of the lateral acceleration signal input means 21 and the calculated value output of the distance calculating means 24. Target stroke calculating means 25 for calculating each target stroke on the right wheel side and the left wheel side, and outputs the respective outputs corresponding to the calculated target strokes on the right wheel side and the left wheel side to each of the corresponding wheels. And a right wheel target stroke output means 26 and the left wheel target stroke output means 27 outputs to the servo amplifier 8. Therefore, the control unit 10
Have the functions of a calculating means, a target stroke calculating means and a control means.

Next, the roll control operation of the suspension control device of the present embodiment will be described with reference to the flowchart of FIG. First, in step 1, the lateral acceleration β from each sensor reads the right wheel load W _R and the left wheel load W _L. In step 2, the read loads W _R,
Distance S _R from the roll center RC based on W _L to the hydraulic cylinders 3 of the right wheel and the left _wheel, it calculates the S _L.

[0015] The distance S _R, the calculation of S _L, as shown in FIG. 5, the distance from the roll center RC when the load allocation during normal loading of the left and right equally to each hydraulic cylinder 3 of the right wheel and left wheel Assuming that S, S _R = [W _L / (W _R + W _L )] 2S (1) S _L = [W _R / (W _R + W _L )] 2S (2) In the figure, m indicates the mass, and the dashed line indicates the single stack state.

[0016] In step 3, the distance S _R, the target stroke of the target stroke Y _R and the left wheel side of the hydraulic cylinder on the right wheel side of the hydraulic cylinder on the basis of the S _L calculated in lateral acceleration β and Step 2 read in step 1 and Y _L are calculated by the calculation formula below. _{Y R = (mβH / 2S R} K) A ··· (3) Y L = (mβH / 2S L K) A ··· (4) mass m _{is, m = (W R + W} L) / g (g : Gravity acceleration)
And H is the distance from the roll center to the mass m,
K is a spring constant of the auxiliary spring 4 of the suspension. Also, A is, A = 1 - a ^{_{[(S R 2 + S L 2}} ) / 2S 2 ].

Here, the calculation of the target stroke will be described. From FIG. 6, assuming that there is no force generated by the hydraulic cylinder, the roll angle θ at the time of normal loading with the center of the roll at the symmetrical position is: θ = mβH / 2KS ² (5) On the other hand, the roll angle at the time of single loading theta 'is, θ' = mβH / K ( S R 2 + S L 2) ··· (6) where, during stacking pieces, the generation force of the right wheel side and the left wheel side of the hydraulic cylinder F _R, F _L Then , theta 'is, θ' = mβH- become _{(F R S R + F L} S L) / K (S R 2 + S L 2) ·· (7).

To the [0018] theta = theta 'is (5) and (7) from _{F R S R + F L S} L = mβH ^{_{[1- (S R 2 + S L}} 2) / 2S 2 ] · ( 8) Here, if _{F R S R = F L S} L, 2F R S R = mβH ^{_{[1- (S R 2 + S L}} 2) / 2S 2 ] (9) next, F _R = (mβH / 2S _{R) ^{[1- (S R 2 + S L}} 2) / 2S 2 ] a ... (10).

[0019] Similarly, F _{L is, F L = (mβH / 2S} L) ^{_{[1- (S R 2 + S L}} 2) / 2S 2 ] a ... (11). In this embodiment, since the position control, the target stroke of the right wheel side and the left wheel side Y _R, Y _{L, respectively, Y R = F R / K} = (mβH / 2S R K) [1-(S _{R ^{2 + S L 2) / 2S}} 2 ] _{·· (12) Y L = F} L / K = (mβH / 2S L K) ^{_{[1- (S R 2 + S L}} 2) / 2S 2 ] ... (13) becomes , 1 - if put as ^{_{[(S R 2 + S L 2}} ) / 2S 2 ] = a, (3) equation (4) is obtained.

[0020] In step 4, and outputs the target stroke Y _R calculated in Step 3, the signals corresponding to Y _L to the respective corresponding servo amplifiers 8 of the right wheel side and the left wheel side. The servo amplifier 8, wherein each target stroke outputted from the control unit 10 Y _R, as Y _L and the actual stroke by comparing the actual stroke from the stroke sensor 9 coincides target stroke Y _R, the Y _L The flow control valve 6 for each wheel is drive-controlled to adjust the supply and discharge amount of hydraulic oil to and from the corresponding hydraulic cylinder 3.

As described above, the target stroke of each wheel is set based on the load distribution of the left and right wheels of the vehicle. Sometimes, the same roll angle can be obtained, and the maneuverability and stability of the vehicle can be improved. In this embodiment,
Although the auxiliary spring is provided, the function of the auxiliary spring may be realized by a hydraulic cylinder. The suspension mechanism is not limited to the configuration of the present embodiment as long as the configuration allows the left and right vehicle heights to be individually varied.

[0022]

As described above, according to the present invention, the target strokes of the right wheel and the left wheel are set according to the load distribution of the left and right wheels of the vehicle. Even in the case of single stacking with different wheel load distributions, the same roll angle can be controlled during right turn and left turn, and the same roll characteristics can be provided irrespective of the turning direction. Therefore,
The maneuverability and stability of the vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining the configuration of the present invention;

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a control unit of the embodiment.

FIG. 4 is a flowchart of roll control of the embodiment.

FIG. 5 is a diagram for explaining an arithmetic expression of a distance from each suspension device to a roll center.

FIG. 6 is a diagram for explaining a target stroke calculation formula;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wheel 2 Axle 3 Hydraulic cylinder 5 Body 6 Flow control valve 7 Hydraulic supply unit 8 Servo amplifier 9 Stroke sensor 10 Control unit 11 Lateral G sensor 12 Right wheel load sensor 13 Left wheel load sensor

Claims (1)

(57) [Scope of request for utility model registration] A vehicle height adjusting means is interposed between a vehicle body and an axle, and a target of the vehicle height adjusting means which is set in advance according to an actual stroke and a traveling state in which a relative displacement between the vehicle body and the axle is detected. In a vehicle suspension control device configured to detect a deviation from a stroke and drive-control the vehicle height adjusting unit so as to match a target stroke, a relative displacement detecting unit that detects a relative displacement between a vehicle body and an axle; Lateral acceleration detecting means, right wheel load detecting means for detecting a load acting on the right wheel of the vehicle, left wheel load detecting means for detecting a load acting on the left wheel of the vehicle, and a detection value of both load detecting means. Calculating means for calculating the respective distances from the mounting positions of the respective vehicle height adjusting means on the right wheel side and the left wheel side to the roll center position; and the distances calculated by the calculating means and the detection values of the lateral acceleration detecting means. Target stroke calculating means for calculating respective target strokes of the right wheel side and left wheel side vehicle height adjusting means in accordance with the ratio of the distances, and relative displacement detecting means for each target stroke calculated by the target stroke calculating means. Control means for driving and controlling the vehicle height adjusting means on the right wheel side and the left wheel side so that the respective detection strokes on the corresponding wheel side detected in the step (c) coincide with each other. apparatus.