JPH1142918A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally control a wheel center locus according to a road surface form in a suspension device in which a change in body style can be suppressed by changing the wheel center locus moving along the upward movement of a wheel. SOLUTION: A distance between a body and a road surface is detected by a ultrasonic wave distance sensor 35, and a wheel speed is detected by a wheel speed sensor 36. Based on the detected data, a road surface height and a distance are obtained and, based on the obtained data, a time when the front wheel rides on a height difference and the target stroke of a suspension link according to a road surface input direction caused by the height difference are calculated. Also the target stroke is output to hydraulic pressure servo circuits 33UF to 33LR so as to operate power cylinders 14UF to 14LR, causing the inclined movement of the body side mounting points of upper and lower links. Thus the tangential line of the wheel center locus is aligned with the road surface input direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a motor vehicle, and more particularly, to a vehicle suspension device that controls the trajectory of a wheel center in accordance with the shape of a road surface so as to ensure the riding comfort of the vehicle.

[0002]

2. Description of the Related Art Conventional suspension devices are described in, for example, Japanese Patent Application Laid-Open No. 6-64436 (hereinafter referred to as a first conventional example) and Japanese Patent Application Laid-Open No. 6-293283 (hereinafter referred to as a second conventional example). There are things that are.

In the first prior art, a suspension member which is connected to an axle member and defines a pitching geometry according to its mounting position is provided in order to suppress pitching of a vehicle during braking or driving, and a suspension member for braking or driving the vehicle. At least one of the disclosed vehicle suspension devices includes anti-pitting geometry changing means for changing the mounting position of the suspension member so as to strengthen the anti-pitting geometry.

[0004] Further, in a second conventional example, in a motorcycle,
When the front wheel rides on a bump on the road surface, the upper and lower swing arms are positioned on the knuckle side so that the direction of the combined force of the rearward and upward forces acting on the front wheel and the locus of the axle of the front wheel substantially match. The four-link mechanism increases the included angle between the straight line connecting the two connecting points and the road surface according to the upward knuckle stroke, and the front wheel is disposed at the end of the lower knuckle on the connecting point side of the lower swing arm. The disclosed front wheel support structure for a motorcycle is disclosed.

[0005]

However, in the above-mentioned first conventional example, when the vehicle is braked or driven, the mounting position of the suspension link is moved to change the geometry, so that the braking and driving are performed. Can suppress the change in the attitude of the vehicle, but there is an unsolved problem that it is difficult to sufficiently improve the riding comfort against the input from the road surface because no consideration is given to the road surface shape .

In the second prior art, the wheel center trajectory is changed together with the stroke caused by the front wheel riding on the projection, so that the wheel starts the stroke at the moment when the wheel comes into contact with the projection. Therefore, there is an unsolved problem that the wheel center locus is maintained in the initial state, and the feeling of thrust remains as before.

Therefore, the present invention has been made in view of the above-mentioned unresolved problems of the prior art, and detects a road surface shape in advance and changes a wheel center locus before a wheel comes into contact with a protrusion. Accordingly, it is an object of the present invention to provide a suspension device capable of smoothing the movement of the wheel when passing through the protrusion.

[0008]

In order to achieve the above object, the invention according to claim 1 suppresses a change in posture by changing a trajectory of a wheel center that moves with upward displacement of a wheel. Road surface shape detecting means for detecting a road surface shape of a road surface on which a wheel passes before a wheel, and a locus change for changing the wheel center locus according to the road surface shape detected by the road surface shape detecting device. Means.

In the invention according to the first aspect, the road surface shape of the road surface on which the wheel passes is detected in advance by the road surface shape detecting means, and the wheel center locus is changed by the locus changing means based on the detection result. It is possible to change the trajectory of the wheel center before the wheel contacts the projection.

According to a second aspect of the present invention, in the first aspect of the present invention, the trajectory changing means is configured to move a vehicle-body-side attachment point of a link supporting a wheel. I have.

In the invention according to claim 2, the vehicle body-side mounting point on the front side of the link that supports the wheels is moved downward by the trajectory changing means, or the vehicle body-side mounting point on the rear side is moved upward, By lowering the center of rotation,
The trajectory of the wheel center can be changed to the upward tendency of the vehicle.

Further, according to a third aspect of the present invention, in the first aspect of the present invention, the trajectory changing means is configured to move a vehicle body-side mounting point of a suspension member for mounting a link supporting a wheel. It is characterized by having.

According to the third aspect of the present invention, by moving the mounting point of the suspension member on the vehicle body by the trajectory changing means, the center of rotation at the time of passing the projection is lowered, and the trajectory of the wheel center is changed to the upward tendency. can do.

Still further, according to a fourth aspect of the present invention, in any one of the first to third aspects, the road surface shape detecting means is configured to detect at least one of a height and an inclination of the projection. It is characterized by having.

According to the fourth aspect of the present invention, the direction of the composite input input to the wheel can be determined by detecting at least one of the height and the inclination of the projection by the road surface shape detecting means.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the trajectory changing means increases the rearward of the wheel center trajectory as the road surface shape change detected by the road surface shape detecting means increases. It is characterized by being configured to strengthen the tendency.

In the invention according to claim 5, the larger the change in the road surface shape detected by the road surface shape detecting means, the larger the input to the rear side with respect to the wheel, and the direction of the combined input approaches the direction parallel to the road surface. In response to this, the rearward tendency of the wheel center trajectory is increased, so that the direction of the synthetic input and the direction of the wheel center trajectory are matched.

Further, the invention according to claim 6 is the invention according to claim 1.
In any one of the aforementioned inventions, the trajectory changing means may include:
When the wheel passes through the projection, the trajectory of the wheel center viewed from the side of the vehicle is changed so as to approach the vertical direction.

According to the sixth aspect of the invention, when the wheel passes through the projection, the vertical input at the time of landing of the wheel becomes a problem. Match.

Further, according to a seventh aspect of the present invention, in any one of the first to sixth aspects, the trajectory changing means keeps the anti-pitching geometry during braking when changing the wheel center trajectory constant. It is characterized in that it is configured to change while maintaining it.

According to the seventh aspect of the present invention, it is possible to reliably prevent the change of the wheel center locus by the locus changing means from affecting the anti-pitch geometry during braking.

[0022]

According to the first aspect of the present invention, the road surface shape detecting means predicts the road surface condition ahead of the wheel and changes the wheel center locus according to the detected road surface shape. The wheel center trajectory can be set according to the road surface shape before it comes into contact with the road surface shape change. The effect of being able to obtain is obtained.

According to the second aspect of the present invention, the vehicle-body-side attachment point on the vehicle front side of the link supporting the wheel is moved downward by the trajectory changing means or the vehicle-body-side attachment point on the rear side is moved upward. By lowering the center of rotation, the trajectory of the wheel center can be changed to be on the front side of the vehicle, and the effect of arbitrarily changing the trajectory of the wheel center according to the road surface shape is obtained. Can be

Further, according to the third aspect of the present invention, the trajectory changing means moves the mounting point of the suspension member on the vehicle body side, thereby lowering the rotation center during braking,
The wheel center trajectory can be changed to be on the front side of the vehicle, and the effect that the wheel center trajectory can be arbitrarily changed according to the road surface shape is obtained.

According to the fourth aspect of the present invention, it is possible to determine the direction of the composite input input to the wheel by detecting at least one of the height and the inclination of the projection by the road surface shape detecting means. As a result, it is possible to obtain the effect that the direction of the combined input and the moving direction of the wheel center locus can be matched.

According to the fifth aspect of the present invention, the larger the change in the road surface shape detected by the road surface shape detecting means, the larger the input to the rear side with respect to the wheel, and the direction of the combined input is a direction parallel to the road surface. It is possible to judge that the vehicle is approaching, and in response to this, the tendency of the wheel center trajectory to rise rearward is increased, so that the direction of the synthetic input and the direction of the wheel center trajectory are made to coincide with each other, and the riding comfort is remarkably improved. The effect that it can be obtained is obtained.

According to the sixth aspect of the invention, when the wheel passes through the projection, the vertical input at the time of landing of the wheel becomes a problem. And the vibration input from the road surface can be absorbed.

Further, according to the present invention, it is possible to prevent the change of the wheel center trajectory by the trajectory changing means from affecting the anti-pitch geometry at the time of braking. The advantage is that the optimum ride quality can be secured without any change in the vehicle.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment when the present invention is applied to a front suspension device.

In the figure, reference numeral 1 denotes a knuckle as a rotation support member for rotatably supporting the front wheel 2.
The upper and lower ends are rotatably connected to a vehicle body side member via an upper link 3 and a lower link 4 formed in an A shape, respectively, to form a double wishbone type suspension.

The upper link 3 has a vertical corner formed at the upper end of the knuckle 1 via a ball joint 5, and cylindrical connecting portions 6 and 7 formed at opposite front and rear ends, respectively.
Bushes 8 and 9 are interposed in the connecting portions 6 and 7, and rotating shafts 10 and 11 are interposed in the center of the bushes 8 and 9.

Support brackets 13UF and 13U in which the rotating shafts 10 and 11 are vertically slidably mounted on a suspension member 12 as a vehicle body-side member.
The support brackets 13UF and 13UR are supported by the power cylinders 14UF and 1
The 4UR piston rod 14b is connected and moved up and down.

On the other hand, the lower link 4 also has a vertex at the lower end of the knuckle 1 via a ball joint 15 and at a front end and a rear end on the opposite side, cylindrical connecting portions 16 and 17 respectively.
Are formed, and the bush 1 is provided in the connecting portions 16 and 17.
8 and 19 are inserted, and rotation shafts 20 and 21 are inserted into the center portions of the bushes 18 and 19, and these rotation shafts 20 and 21 are vertically slidable on a suspension member 22 as a vehicle body side member. The support brackets 13LF and 13LR are supported by the attached support brackets 13LF and 13LR. The support brackets 13LF and 13LR support the piston rods 14 of the power cylinders 14LF and 14LR in which the cylinder tube 14a is fixed to the suspension member 22.
b are connected and moved up and down.

Then, each power cylinder 14UF, 14
Each of the UR and 14LF, 14LR is an upper and lower pressure chamber 14d, defined by a piston 14c, as shown in FIG.
14e is an electromagnetic directional control valve 31U each having 4 ports and 3 positions
Hydraulic source 3 via F, 31UR and 31LF, 31LR
2 and the electromagnetic directional control valves 31UF, 31UR
And 31LF, the solenoid 31LR is S _H and S _L
Hydraulic servo circuits 33UF, 33UR and 33LU, 3
Increase command signal CS _H and descent command signal CS from 3LR
Switching is controlled by inputting _L.

The electromagnetic directional control valves 31UF to 31LR
And upper and lower pressure chambers 1 of power cylinders 14UL to 14LR
A parallel circuit of a check valve 34 and a throttle 35 is interposed between 4d and 14e, respectively, and the power cylinders 14UF to 14LR
The hydraulic oil pushed out from the pressure chamber, which is the return side of, is returned to the hydraulic pressure source 32 through the throttle.

Each of the hydraulic servo circuits 33UF to 33LR
Is the piston rod of each power cylinder 14UF to 14LR.
For example, a potentiometer for detecting the stroke of the head 14b
Sensors 34UF to 34LR composed of data
And the stroke sensors 34UF-34LR
Troke detection value S_UF~ S_LRIs a feedback signal
Input from the controller 40 described later.
Target stroke S _UF ^*~ S_LR ^*And both
Is equal to the control signal CS_HAnd CS_LThe
S_j(J = UF, UR, LF, LR)>
S_j ^*When the control signal CS_HThe off state, control signal
Issue CS_LIs turned on, and S_j<S_j ^*When is
Control signal CS_HOn, control signal CS_LTurn off
Control.

An ultrasonic distance sensor 35 is provided as road surface shape detecting means for detecting the road surface shape through which the front wheels 2 pass, facing the road surface at a position in front of the front wheels 2 of the vehicle. The ultrasonic distance sensor 35 has a transmitter and a receiver for ultrasonic waves, oscillates ultrasonic waves from the transmitter toward the road surface, and receives the reflected waves from the road surface by the receiver. By measuring the time, the distance between the sensor and the road surface is calculated,
A digital distance signal H representing the calculated distance to the road surface is output.

Further, a wheel speed sensor 36 for detecting a wheel speed is disposed on the front wheel 2, and a pulse signal WP corresponding to the wheel speed is output from the vehicle speed sensor 36. The controller 40 receives a pulse signal WP from the wheel speed sensor 36, and calculates a wheel speed V that is a peripheral speed of the front wheel 2 from the pulse signal WP and the wheel diameter. Wheel speed V of circuit 41 and ultrasonic distance sensor 3
Microcomputer 42 to which the distance signal H of No. 5 is input
It is composed of

The microcomputer 42 includes an input / output interface circuit, an arithmetic processing unit, and a storage device (not shown).
5 and the wheel speed V of the wheel speed calculation circuit 41 are input, the road surface shape is detected based on the distance signal H, and the road surface on which the front wheels 2 are going to pass based on the wheel speed Vw and the road surface shape. A wheel center trajectory WC corresponding to the shape is calculated, and the ascending and descending positions of the power cylinders 14UF to 14LR are determined according to the calculated wheel center trajectory WC, and the target strokes S _UF ^{* to} S _LR ^* according to the ascending and descending positions are calculated. Output to the hydraulic servo circuits 33UF-33LR.

More specifically, the microcomputer 42
Then, the target value calculation processing shown in FIG. 3 and the target value output processing shown in FIG. 6 are executed. That is, the calculation processing of FIG. 3 is executed as a timer interruption processing every predetermined time (for example, 10 msec). First, in step S1, the distance signal H (n) of the ultrasonic distance sensor 35 and the wheel speed V of the wheel speed calculation circuit 41 are set. (n) is read, and then the process proceeds to step S2 to store the read distance signal H (n) and wheel speed V (n) in a shift register area having a predetermined number m of stages formed in the storage device.

Next, the process proceeds to step S3, where it is determined whether or not the wheel speed V (n) exceeds a set wheel speed _VMIN which is a threshold value for determining whether or not to continue the preset control.
When (n) ≦ V _MIN, it is determined that there is no need to perform control, the timer interrupt process is terminated, and the process returns to the predetermined main program. When V (n)> V _MIN , control is not performed. It is determined that the operation is to be continued, and the process proceeds to step S4.

In this step S4, the cutoff frequency of the time series data of the distance signals H (n) to H (nm) stored in the shift register area is changed to the bounce on the spring,
A high-pass filter process is performed in which the frequency is set to be slightly higher than the largest of the pitch and roll resonance frequencies. This high-pass filter processing is based on the fact that the distance signal H (n) of the ultrasonic distance sensor 35 measures not the road surface shape itself but the distance between the vehicle and the road surface. Although the behavior is included, it is performed for the purpose of removing sprung vibration components so that the distance between the road surface and the vehicle is regarded as the road surface shape.

That is, above the sprung resonance frequency, the sprung behavior of the vehicle is sufficiently small, and it can be seen that the vehicle body hardly moves vertically in the absolute coordinate system.
In this case, the distance between the vehicle and the road surface can be regarded as the road surface shape. However, since the sprung behavior of the vehicle is not small near the sprung resonance frequency, the value of the ultrasonic distance sensor includes the sprung movement, and this cannot be regarded as the road surface shape. Therefore, by performing high-pass filter processing, components below the sprung resonance frequency region are removed. Even if components below the sprung resonance frequency region are removed, the sprung resonance frequency is generally about 1 to 2 Hz for both bounce, pitch, and roll. The period of the road surface causing the vibration of the region is very long, and almost no force is applied to the wheels in the front-rear direction. Therefore, there is almost no problem even if the control is not performed by removing this frequency component.

Next, the process proceeds to step S5, in which the change amount ΔH is calculated by subtracting the current high-pass filter processing value Hf (n) from the previous high-pass filter processing value Hf (n-1), and then proceeds to step S6. The process proceeds to determine whether or not the level difference detection flag F indicating a state where a level difference or the like is being detected is set to "1". If the level difference detection flag F is set to "1", the flow directly jumps to step S9 described later. And
If it has been reset to "0", it is determined that a step or the like has not been detected, and the routine proceeds to step S7.

In this step S7, it is determined whether or not the absolute value | ΔH | of the amount of change ΔH is equal to or larger than a threshold value ΔH _S for judging a shape change such as a step difference.
When | <ΔH _S , it is determined that the road surface is flat, the timer interrupt processing is terminated, and the process returns to the predetermined main program. When | ΔH | ≧ ΔH _S , there is a shape change such as a step. Then, the process proceeds to step S8, where the level difference detection flag F is set to "1", and then proceeds to step S9.

In this step S9, it is determined whether or not the absolute value | ΔH | of the amount of change ΔH is smaller than a threshold value ΔH _S.
When ΔH | ≧ ΔH _S, it is determined that the detection of a step or the like is continuing, and the timer interrupt processing is terminated as it is.
When | ΔH | <ΔH _S, it is determined that the detection state of a step or the like has shifted to the detection state of a flat road surface, and the flow shifts to step S10.

In this step S10, based on the wheel speed V (n), the sampling period T _S, and the high-pass filter processing values Hf (n) to Hf (nm) of the distance signals H (n) to H (nm) As shown in FIG. 4, the road surface shape is estimated by forming a characteristic diagram in which the horizontal axis represents the distance L and the vertical axis represents the road surface height _HL . Here, the distance L on the horizontal axis is the wheel speed V (i) (i =
n, n−1... nm) and the sampling time T _S , and the road surface height H is a high-pass filter value Hf (n) to Hf (nm).

Next, the process proceeds to step S11, and based on the road surface shape estimated in step S5, as shown in FIG. 5, the height H and inclination K of the step or the like when the wheel rides, and the front wheel 2 Distance X until the vehicle rides,
Front wheels 2 calculates the level difference running distance X _C from rides on the step until it reaches the top of the step.

Next, the process proceeds to step S12, in which the height H and the slope K of the step or the like calculated in step S10 are calculated.
The direction of the force applied to the front wheels 2 from the road surface is calculated with reference to the three-dimensional control map shown in FIG.

This three-dimensional control map is basically similar to that shown in FIGS. 7A, 7B and 7C when riding on a step.
As shown in (d), the setting is based on the fact that the road surface input angle θ represented by the angle formed with the vertical line increases as either the height H of the step or the like or the inclination K increases, It is formed in consideration of the fact that there is a region where the height H of the step or the like and the inclination K become large and there is a peak.

That is, as shown in FIGS. 7 (e) and 7 (f), when the height of the step becomes a predetermined value or more, the optimum moving direction of the wheel center trajectory does not depend on the height of the step, and the inclination of the step becomes smaller. Also, when the inclination is equal to or more than a predetermined value, the optimal moving direction of the wheel center locus does not depend on the inclination.

As a result, in the three-dimensional control map of FIG. 6, for example, the road surface input angle θ increases as the slope K increases until the slope K reaches 45 degrees at the height H _4. road surface input angle regardless the increase of the inclination K theta is constant value in the above degrees, when the inclination K is 45 degrees to the contrary, increase of the height H is between up to a height H reaches H ₄ Correspondingly Although the road surface input angle θ increases, the road surface input angle regardless of the increase in the height H is at H ₄ or θ is set to be constant values.

Considering the time of stepping over a step, the axle starts dropping due to the loss of the wheel load from the stepping, and a vertical vertical force acts on the road surface as shown in FIG. Unlike the case of riding, the input from the road surface moves vertically up and down, and the road surface input angle θ is set to “0” representing the vertical input state in the region where the height H is negative as shown in FIG.

Next, the process proceeds to step S13, in which the target of the vehicle body side attachment point of each of the links 3 and 4 necessary for making the tangential direction of the wheel center locus WC coincide with the road surface input angle θ calculated in step S12. Stroke S _UF ^* ~
_SLR ^* is calculated, and these are updated and stored in the target stroke storage area formed in the storage device.

Next, the process proceeds to step S14 to output the calculated target strokes S _UF ^{* to} S _LR ^* to the respective hydraulic servo circuits 33UF to 33LR, that is, the delay time T _W from the present time to the wheel speed V (n). And the step S6
Is calculated in accordance with the following equation (1) based on the arrival distance X calculated in step (1), and the following equation (2) is calculated based on the step running distance X _C and the wheel speed V (n) to obtain the control duration time T. _C is calculated, and the calculated delay time T _W and control duration T _C are stored in the delay time storage area and the control duration storage area of the storage device.

T_W= X / V (n) -T_D ……… (1) where X / V (n) is the distance traveled divided by the wheel speed
Represents the arrival time, and T _DIs the actuator response delay
It is the operation delay time of a machine or an electronic circuit.

T _C = X _C / V (n) + α (2) where α is a preset control allowance time. Next, the process proceeds to step S15, where the level difference detection flag F is reset to "0", the timer interrupt process is terminated, and the process returns to the predetermined main program.

Also, the microcomputer 42 is provided in FIG.
The target value output process shown in FIG.
c) Execute as a timer interrupt process for each. The target value output process, first, in step S21, determines whether or not it is clear to the delay time T _W is "0" stored in the delay time storage area, when it is T _W> 0, the above In the target value calculation process shown in FIG. 3, it is determined that the delay time T _W has been set, and the process shifts to step S22 to subtract a value “1” from the delay time T _W to obtain a new delay time T _{W. After} being updated and stored in the delay time storage area as _W , the process proceeds to step S23.

In this step S23, the delay time T_WBut
It is determined whether or not “0” has been reached. _WWhen> 0
Terminates the timer interrupt processing and
Return to Gram, T_W= 0, the storage device
Target straw stored in target stroke storage area
Ku S_UF ^*~ S_LR ^*The hydraulic servo circuits 33UF-33LR
To the specified main
Return to the program.

On the other hand, when the result of determination in step S21 is that the delay time T _W is “0”, the flow proceeds to step S25, where the control duration T _C stored in the control duration storage area of the storage device is determined. "0" to determine whether it is cleared, it is determined that when a T _C> 0 is passing through the control of the step or the like, the process proceeds to step S26, "from the current transition period T _C 1 "the transition from the update stored in the control continuation time storage area subtracted value as a new control duration T _C in step S27.

In step S27, the control continuation time T
_It is determined whether or not _C has become “0”. If T _C > 0, it is determined that passage control such as a step is being performed, and the timer interrupt processing is terminated as it is. If T _C = 0, ,
It is determined that the control continuation time T _C has passed and the vehicle has passed a step or the like, and the process proceeds to step S28, where the preset reference target strokes SS _UF ^{* to} SS _LR ^* are transmitted to the hydraulic servo circuits 33UF to 33LR. After the output, the timer interrupt process is terminated and the process returns to the predetermined main program.

Next, the operation of the first embodiment will be described. Now, the vehicle is traveling on a flat paved road at a vehicle speed _{equal to} or higher than the set vehicle speed VMIN, the level difference detection flag F is cleared to "0", and the hydraulic servo circuits 33UF to 33LR are provided.
Assuming that the reference target strokes SS _UF ^{* to} SS _LR ^* have been output to ensure optimal riding comfort when traveling on a flat road surface, in this state, the distance between the vehicle body and the road surface is constant. Therefore, the distance signal H (n) detected by the ultrasonic distance sensor 35 should be constant. However, in actuality, when the vehicle body moves up and down, a vibration component equal to or lower than the sprung resonance frequency component is superimposed. Fluctuating.

However, in the target value calculation processing of FIG.
The distance signal H (n) of the ultrasonic distance sensor 35 and the wheel speed V (n) of the wheel speed sensor 36 are read and stored in the shift register area. H (n) to H (nm) and V (n)
~ V (nm) is stored.

Then, the time series data H (n) to H (nm) of the distance signal stored in the shift register area are subjected to high-pass filtering, so that the resonance frequency below the sprung resonance frequency due to the vibration of the vehicle body is obtained. By removing the vibration component, high-pass filter values Hf (n) to Hf (nm) corresponding to the actual distance between the ultrasonic distance sensor 35 and the road surface can be obtained.

At this time, since the vehicle is traveling on a flat pavement, the values of the change ΔH calculated in step S5 become substantially equal when the values of the bypass filters Hf (n) to Hf (nm) become substantially equal. Since it becomes “0”, | Δ
It is determined that H | <ΔH _S, and the timer interrupt processing is terminated as it is.

Therefore, the delay time T _W is not set in the delay time storage area of the storage device, and the control duration T _C is not set in the control duration storage area. The stored value is “0”.

As a result, when the target command value output processing of FIG. 8 is executed, the timer interrupt processing is terminated as it is via steps S21 and S25, and the reference target strokes SS _UF ^{* to} SS _LR ^* Output state is continued.

For this reason, the vehicle body-side attachment points of the upper link 3 and the lower link 4 are controlled to the stroke positions at which the optimum riding comfort is ensured when traveling on a flat road surface. While traveling on this flat pavement, the ultrasonic distance sensor 3
5, when a step on the road surface is detected, the distance signal H at that time is detected.
(n) is the overall previous value Hf (n).
-1) Since the distance is shorter, the change amount ΔH calculated in step S5 is positive and larger than the threshold value H _S.
After step S7, the process proceeds to step S8, where the level difference detection flag F is set to "1".
Since ΔH |> H _S , the timer interrupt processing is terminated as it is.

Therefore, even at this time, the target strokes S _UF ^{* to} S _LR ^* , the delay time T _W, and the control continuation time T _C
Is not stored in the corresponding storage area.
Even if the processing of step S2 is executed, steps S21 to S2
By ending the timer interrupt processing via 5, the output states of the reference target strokes SS _UF ^{* to} SS _LR ^* to the hydraulic servo circuits 33 _{UF to} 33 _LR are continued.

Thereafter, every time the target value calculation processing of FIG. 3 is executed, the distance signal H of the ultrasonic distance sensor 35 to be read is read.
(n), the distance | ΔH | ≧ ΔH _S is maintained, so that the reference target strokes SS _UF ^{* to} S
The output state of S _LR ^* is continued.

However, when the target value calculation processing is executed, as shown in FIG. 5, the high-pass filter value Hf (n) representing the actual distance between the vehicle body and the road surface is changed to the previous value Hf (n-1).
Is smaller than the threshold value H _S , it is determined that the state of detecting the step has ended, and the process proceeds from step S9 to step S10, whereby the road surface shape is estimated as shown in FIG. Next, step S11
Then, the reaching distance X, the control continuation distance X _C , the step height H, and the step slope K are calculated.

Next, the process proceeds to step S12, where the road surface input angle θ is calculated with reference to the three-dimensional control map of FIG. 6, and based on this, the target stroke at the vehicle body side attachment point of each of the links 3 and 4 is determined in step S13. S _UF ^{* to} S _LR ^* are calculated and stored in the target stroke storage area of the storage device. Further, in step S 14, a delay time T _W and a control continuation time T _C until the front wheel 2 reaches the step are calculated. These are stored in the delay time storage area and the control duration time storage area, respectively, and then the process proceeds to step S15, where the level difference detection flag F is reset to “0”.

By storing the delay time T _W and the control continuation time T _C in the delay time storage area and the control continuation time storage area in this way, when the target value output processing of FIG. The delay time T _W is sequentially decremented, and when it becomes “0”, the target strokes S _UF ^{* to} S _LR ^* stored in the target stroke storage area are output to the hydraulic servo circuits 33UF to 33LR.

Therefore, the hydraulic servo circuits 33UF to 33UF
In LR, the input target stroke S_UF ^*~ S_LR ^*When
Stroke detection of stroke sensors 34UF to 34LR
Value S _UF~ S_LRAnd if the deviation is positive or negative
For the electromagnetic directional control valves 31 UF to 31 LR
Control signal CS_UAnd CS_LOn / off control.

In response to this, immediately before the front wheel 2 actually reaches the step, the tangent of the wheel center trajectory at the vehicle body-side attachment point of the upper link 3 and the lower link 4 is input according to the step height H and the step slope K. Is moved so as to be substantially equal to the angle of the road surface input.

[0076] That is, when the height H is small or the slope K of the step is small, a relatively small inclination of the upper link 3 and lower link 4 as shown by the solid line shown in FIG. 9, the instantaneous center of rotation O _L is the wheel center O _WC and substantially matches, but tangents of the wheel center locus is substantially a vertical direction, the upper link 3 and as indicated by the broken line shown in FIG. 9 when the height H is greater or inclination K of the step is greater The inclination of the lower link 4 is large, the instantaneous rotation center O _H is below the wheel center O _WC , and the tendency of the rear center to rise rearward increases so that the tangent of the wheel center locus coincides with the road surface input direction (the tangent approaches the horizontal). Come).

Therefore, the road surface input to the front wheel 2 due to the step can be reliably absorbed by the rearward upward movement of the front wheel 2, and a good ride comfort can be secured.

As described above, when the delay time T _W is cleared to “0”, the next time the target value output process of FIG. 8 is executed, the process shifts from step S 21 to step S 25, and the control continuation time T _C Is set in the control duration storage area, the process proceeds to step S26, and the control duration T _C is sequentially decremented. When this value becomes “0”, that is, it is determined that the front wheel 2 has finished passing through the step. When this is done, the process moves to step S28, and the reference target strokes SS _UF ^{* to} SS _LR ^* are again adjusted to the hydraulic servo circuits 33UF to 33L.
Output to R.

Therefore, when the front wheel 2 has passed through the step or slightly later, the vehicle body-side attachment points of the links 3 and 4 are returned to the reference stroke, and the optimum position for the flat road surface is obtained. Is returned to.

In the meantime, in the target value calculation processing of FIG. 3, the step detection based on the variation ΔH, which is the deviation between the high-pass filter value H (n) and the previous value H (n−1), is continued. When the vehicle continues to travel on a flat road surface, the vehicle body side attachment points of the links 3 and 4 are maintained at the reference stroke.

On the other hand, when the road surface shape detected by the ultrasonic distance sensor 35 is a protrusion, when the vehicle rides on the up slope of the protrusion, the same processing as the above-described step is performed, and the height H of the protrusion is obtained. And the wheel center trajectory corresponding to the road surface input angle θ according to the slope K, but as shown in FIG. 10, immediately before the front wheel 2 actually reaches the projection, the distance signal H (n ), The absolute value of the negative change ΔH, which is the difference between the high-pass filter value Hf (n) and the previous value Hf (n−1), is smaller than the threshold value ΔH _S. The inclination K, the reach distance X, and the control continuation distance X _C are calculated, are stored in the corresponding storage areas, and the delay time T _W and the control continuation time T _C are calculated.
_C is calculated and these are also stored in the storage area.

Therefore, just before the front wheel 2 approaches the descending slope, the tangent of the wheel center trajectory is controlled to an angle corresponding to the vertical road surface input in preparation for landing, so that the tangent of the wheel center trajectory after passing over the actual projection of the front wheel 2 is obtained. The vertical force input from the road surface at the time of landing can be reliably absorbed.

Thereafter, when the control continuation time T _C has elapsed, the reference target strokes SS _UF ^{* to} SS _LR ^* are output to the hydraulic servo circuits 33 _{UF to} 33 _LR , and the links 3, 4.
Is returned to the reference stroke.

As described above, according to the first embodiment, the trajectory of the wheel center can be made coincident with the road surface input direction due to the step with respect to the front wheel 2 before the front wheel 2 reaches the step or the like. A good ride can always be ensured.

Further, according to the first embodiment, since the vehicle body-side mounting points of the upper link 3 and the lower link 4 are moved, the amount of movement per each mounting point can be small, and the degree of freedom of layout is large. There is an advantage that it becomes.

Further, control is performed as in the first embodiment.
Duration T_CEven if is set with a margin, the target value in FIG.
In the output processing, the delay time T_WIs set
Since the determination as to whether or not the control is performed first, the control continuation time T_CHas passed
The next delay time T _WIs set
Is the delay time T_WStroke control according to
Control delay when riding on a step.
And not.

In the first embodiment, the case where the tangent of the wheel center locus L _WC of the front wheel 2 is controlled such that the tangent of the wheel center locus L _WC of the front wheel 2 coincides with the road surface input direction inputted to the front wheel 2 by the step when riding on the step. However, it is not always necessary to make the tangent of the wheel center locus coincide with the road surface input direction, and depending on the size of the bushing of the upper link 3 and the lower link 4 on the vehicle body side mounting portion and the configuration of the suspension, the upper link 3 and the lower link 4 may be changed. Of the wheel center trajectory may not be enough to match the road surface input direction, but if the tangent of the wheel center trajectory when climbing a step can be brought as close as possible to the road surface input direction. The ride comfort can be improved accordingly.

In the first embodiment, the case where the wheel center trajectory of the front wheel 2 is changed according to the road surface shape has been described. However, the present invention is not limited to this. may be the wheel center trajectory of wheel 50 so as to change according to the road shape, in this case, at the time of riding the small step and substantially equal height instantaneous center of rotation O _L as indicated by a solid line shown with the wheel center O _WC However, when riding on a large step, the vehicle body side connecting portion 45 on the front side of the upper link 43 is moved upward as shown by a broken line,
Conversely, the rear vehicle body-side connecting portion 46 is moved downward, the front vehicle body-side connecting portion 47 of the lower link 44 is moved upward, and conversely, the rear vehicle body-side connecting portion 48 is moved downward. Accordingly, by setting a position above the instantaneous rotation center O _H wheel center O _WC, change the wheel center locus rearwardly upwards, to match the tangent with the road surface input direction.

Further, the trajectories of the wheel centers of both the front and rear wheels may be changed according to the road surface shape. Furthermore, in the first embodiment, the upper link 3
And the vehicle body side connecting portions 6, 7 and 26, 2 of the lower link 4
7 has been described, but the present invention is not limited to this. If the rear wheel 50 is described, FIG.
As shown in FIG. 2, the upper link 43
Front only side connecting portion 45 by moving compared to larger upward in the case of FIG. 11, the rear wheel from the instantaneous center of rotation O _L of and small step at below than the instantaneous center of rotation O _H wheel center O _WC of The wheel center locus may be changed rearward upward as the 50 side, and furthermore, both the front connecting portion 45 and the rear connecting portion 46 of the puncture 43 are moved, and the front link of the lower link 44 with these components. Either the portion 47 or the rear connecting portion 48 may be moved, and the same applies to the front wheel 2. According to the configuration of FIG. 12, the number of moving points can be reduced as compared with the first embodiment, so that the number of actuators such as power cylinders and control circuits can be reduced, and the cost can be reduced accordingly. be able to.

Further, in the above embodiment,
The case where the present invention is applied to a double wishbone type suspension having upper and lower A-shaped links has been described. However, the present invention is not limited to this, and the lower link 4 is omitted as shown in FIG. In place of this, even in the case of a double wishbone type suspension applying a radius rod 80 extending in the vehicle front-rear direction,
In the same manner as in the first embodiment, the front end side connection portion 6 and / or the rear end side connection portion 7 in the vehicle body side attachment portion of the upper link 3 are moved according to the size of the step or the like, or simultaneously with or independently of this. By moving the mounting portion of the radius rod 80 on the vehicle body side, the tangent of the wheel center locus _LWC at the time of stepping can be changed so as to coincide with the road surface input direction, thereby improving ride comfort.

In addition to the double wishbone type suspension, the A-shaped lower link 4 as shown in FIG. 14 is used, and the upper link 3 is replaced with two front upper links 3a and a rear upper link 3b. Even if the multi-link suspension has a configuration in which a lateral link 81 extending in the vehicle width direction is connected to the rear end side of the knuckle 1 and a step on the road surface is detected,
Whether the front upper link 3a is to be moved to the vehicle body side, the rear upper link 3b is to be moved to the vehicle body side, the lower link 4 is to be moved at the front end side connecting portion 26 at the vehicle body side attachment point, or the rear end side is to be moved. By moving the connecting portion 27 or moving a plurality of points among them, the same operation and effect as in the first embodiment can be obtained.

Further, an A-shaped lower link 82 connected to the lower end of the knuckle 1 as shown in FIG.
In the strut type suspension provided with the shock absorber 83 in which the cylinder tube 83a is connected to the state described above and the upper end of the piston rod 83b is connected to the vehicle body-side member, an A-shaped suspension is detected when a step on the road surface is detected. By moving the front end side or the rear end side of the lower link 4 at the vehicle body side mounting point of the lower link 4, or by performing both of them, simultaneously moving the vehicle body side mounting point of the shock absorber 83 to the vehicle body front side, during rides large step to the instantaneous rotation center O _H in and a high position in the vehicle front side with respect to the wheel center O _WC as shown by the solid line shown, the front side of the vehicle body relative to the wheel center O _WC as shown by the broken line shown at rides small step in can be changed and lower instantaneous center of rotation O _L, which foil center locus L _WC changed according to the road shape by the The same functions and effects as those of the first embodiment can be obtained.

Further, as shown in FIG. 16, a trailing arm 85 whose vehicle body side attachment point is located at a higher position on the front side of the wheel center _OWC as shown in FIG. In the torsion beam type suspension provided with the torsion beam 86 connecting the trailing arm 85, the rotation center of the wheel center _{OWC is} the mounting point of the trailing arm 85 on the vehicle body side. The mounting point on the vehicle body side is lower than the wheel center O _WC as shown by the broken line to lower the instantaneous rotation center _OL , and when a large step is detected, the mounting point of the trailing arm 85 on the vehicle side as shown by the solid line. _Is higher than the wheel center O _WC and the instantaneous rotation center O _H is higher, so that the wheel center locus L _WC
Can be changed according to the road surface shape, and the same operation and effect as in the first embodiment can be obtained.

Further, as shown in FIG.
An A-shaped semi-trailing arm 91 is vertically rotatably mounted on a suspension member 90 formed in a V-shape viewed from above, and a wheel is supported on the outer end of the semi-trailing arm 91 on the vehicle body. Even if it is a so-called semi-trailing type suspension in which an axle is formed, a straight line connecting the center axes of the connecting portions 92 and 93 of the semi-trailing arm 91 to the suspension member 90 and a straight line connecting the wheel centers of the left and right wheels. By considering a triangle surrounded by a straight line extending forward through the wheel center, a line connecting the central axes of the connecting portions 92 and 93 in a rear view is normally set as shown in FIG. because it has a dihedral theta _H Te, the instantaneous center of rotation O _U
Is located on the front side of the vehicle with respect to the wheel sensor _OWC as shown in FIG. 17C, and above the wheel sensor _OWC . When a large step is detected, as shown in FIG. When the line connecting the central axes of the connecting portions 92 and 93 on the vehicle body side is set to be a dihedral angle θ _L with respect to the horizontal line, the instantaneous rotational center O _H is raised, and when a small step is detected, FIG.
As shown in FIG. 8B, the line connecting the central axes of the connecting portions 92 and 93 on the vehicle body side of the trailing arm 91 is set substantially equal to the horizontal line to lower the instantaneous center of rotation, so that the wheel can be adjusted according to the road surface shape. The center trajectory can be changed, and the same operation and effect as in the first embodiment can be obtained.

In the first embodiment and the modified example, the case where the wheel center locus _LWC is changed to a forward rising tendency by moving the vehicle body attachment point of the link constituting the suspension has been described. However, the present invention is not limited to this. As shown in FIG. 19, a front upper link 101 and a rear upper link 10
When all the vehicle-side mounting points of the lower link 103 having the 2 and A-shape are mounted, when a large step is detected, FIG.
At 0, the suspension member 10 is set as the position shown by the solid line.
Instantaneous rotation center O _H by each link attached to 0
Is set at a high position on the front side of the vehicle with respect to the wheel center _OWC , and when a small step is detected, the front body connecting portion 104 of the suspension member 100 is lowered and the rear body connecting portion 105 is raised. by, it is possible to reduce the instantaneous center of rotation O _L, the wheel center locus L _WC changed in accordance with the road shape, it is possible to obtain the same effect as the first embodiment is due to .

The actuator for moving the suspension member 100 with respect to the vehicle body is shown in FIG.
As shown in FIG. 1, an electric motor 111
Is fixed, and the screw shaft 112 is integrally attached to the rotation shaft,
The connecting rod 11 is connected to a nut 113 screwed to the screw shaft 112.
4, the connecting rod 114 penetrates the vehicle body-side member 110 and protrudes downward from the vehicle body, and an insulator 115 constituting the vehicle body-side connecting portion 104 of the suspension member 100 is mounted on the lower end of the connecting rod 114. Good.

Further, in the first embodiment and each of the modifications, the case where the instantaneous rotation center is arbitrarily set at the time of riding over a small step or the like and at the time of riding over a large step has been described. However, the present invention is not limited to this. 22, the rear wheel 50 will be described. For example, the rear wheel 50 is represented by an angle formed by a straight line _LUL connecting the instantaneous rotation center _OL and the wheel ground point when riding on a small step or the like and the road surface. When the anti-lift angle θ _UL at the time of braking is set, the instantaneous center of rotation controlled according to the road surface shape as well as the instantaneous center of rotation O _H at the time of riding over a large step is set on the straight line L _UL , so that during braking, The wheel center locus can be changed according to the road surface shape without affecting the anti-lift geometry of the vehicle, and the anti-lift effect during braking can be kept constant. Also,
The anti-dive effect at the time of braking can be kept constant by setting the front wheels in the same manner.

Furthermore, in the first embodiment and each of the modifications, the power cylinders 14UF to 14CF are used as actuators for moving the attachment points of the links 3 and 4 on the vehicle body side.
The case where the 14LR and the hydraulic servo circuits 33UF to 33LR are applied has been described. However, the present invention is not limited to this. An electric motor is fixed to a suspension member, and a screw shaft of a ball screw is connected to a rotation shaft of the suspension member.
The ball nut of this ball screw is connected to the rotating shafts 10, 11, 3
0 or 31, or the ball nut is rotated by an electric motor, and the screw shaft is mounted on the rotation shafts 10, 11, 30, 31 or the brackets 13, 14, 33, 34, thereby electrically connecting the shafts with the road surface shape. It may be driven, and another linear moving mechanism may be applied.

Furthermore, the first embodiment and each of the modifications
In the embodiment, the eye in the microcomputer 42 is used.
In the standard value calculation process, the amount of change
When the target stroke S becomes smaller_UF ^*~ S_LR ^*To
Although the case of calculating has been described, as described above,
Optimum height H is more than a certain size
The tangent direction of the wheel center locus does not depend on the step height
Therefore, the change amount ΔH is accumulated from the time of detecting the step, and this is
At the time when the value exceeds a predetermined value, the target stroke S_UF ^*~ S_LR
^*May be calculated.

In the first embodiment and each of the modifications, the target strokes S _UF ^{* to} S _UF ^{* to} S
_{Although the case where LR} ^* is continuously changed has been described, the present invention is not limited to this, and it is also possible to change _LR ^* into a plurality of stages of two levels larger or smaller or more.

Further, in the first embodiment and each of the modifications, the case where the ultrasonic distance sensor 35 is applied to the detection of the road surface state has been described. Other non-contact type distance sensors can be applied.

Further, in the first embodiment and each of the modifications, the case where the wheel speed is detected by the wheel speed sensor 36 has been described. However, the present invention is not limited to this.
For example, a vehicle speed sensor provided on the output side of the transmission or a vehicle speed used for antilock brake control or the like can be used.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part showing a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a control device applicable to the first embodiment.

FIG. 3 is a flowchart illustrating an example of a target value calculation process in the control device of FIG. 2;

FIG. 4 is an explanatory diagram showing time-series data of a high-pass filter processing value representing a road surface height of a distance signal.

FIG. 5 is an explanatory diagram for obtaining a required control amount from a road surface shape.

FIG. 6 is an explanatory diagram showing a three-dimensional control map for calculating a road surface input angle from a step height and a slope.

FIG. 7 is an explanatory diagram showing a relationship between a road surface shape and a road surface input direction for forming a three-dimensional control map.

FIG. 8 is a flowchart illustrating an example of a target value output process in the control device of FIG. 2;

FIG. 9 is an explanatory diagram for explaining an operation when changing the wheel center locus in the first embodiment.

FIG. 10 is an explanatory diagram for obtaining a required control amount from a road surface shape when passing through a protrusion.

FIG. 11 is an explanatory diagram for explaining an operation when the present invention is applied to a rear wheel.

FIG. 12 is a skeleton diagram showing a modification of the first embodiment.

FIG. 13 is a skeleton diagram showing an example in which the present invention is applied to a radius rod type double wishbone suspension.

FIG. 14 is a perspective view showing an example in which the present invention is applied to a multilink suspension.

FIG. 15 is a skeleton diagram showing an example in which the present invention is applied to a strut type suspension.

FIG. 16 is an explanatory diagram showing an example in which the present invention is applied to a torsion beam type suspension.

FIG. 17 is an explanatory diagram showing an example in which the present invention is applied to a semi-trailing arm suspension.
(A) is a plan view, (b) is a rear view, and (c) is a side view.

FIG. 18 is a rear view for explaining the operation in FIG. 21;

FIG. 19 is a perspective view showing an example in which the present invention is applied to a suspension in which all link systems are attached to suspension members.

FIG. 20 is a skeleton diagram for describing the operation of FIG. 23;

FIG. 21 is a cross-sectional view illustrating an example of an actuator that moves a suspension member.

FIG. 22 is a skeleton diagram showing a modified example when the anti-lift effect during braking is kept constant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Knuckle 2 Wheel 3 Upper link 4 Lower link 6 Front end side connection part 7 Rear end side connection part 10,11 Rotary shaft 12 Suspension member 13UF-13LR Support bracket 14UF-14LR Power cylinder 16,17,26,27 Body side connection part 33UF-33LR Hydraulic servo circuit 34UF-34LR Stroke sensor 35 Ultrasonic distance sensor 36 Wheel speed sensor 40 Controller 41 Wheel speed calculation circuit 42 Microcomputer 3a Front upper link 3b Rear upper link 81 Lateral link 82 Lower link 83 Shock absorber 85 Trailing Arm 86 Torsion beam 100 Suspension member 101 Front upper link 102 Rear upper link 103 Lower link 104 Front end side connection part 105 Rear end side connection part 110 Electric motor 112 Screw shaft 113 Nut 114 Connection rod

Claims (7)

[Claims] 1. A suspension system in which a posture change is suppressed by changing a wheel center trajectory that moves in accordance with an upward displacement of a wheel, wherein a shape of a road surface on which the wheel passes before the wheel is determined. A suspension device comprising: a road surface shape detecting means for detecting; and a trajectory changing means for changing the wheel center trajectory in accordance with the road surface shape detected by the road surface shape detecting means. 2. The suspension device according to claim 1, wherein said trajectory changing means is configured to move a vehicle body-side attachment point of a link supporting a wheel. 3. The suspension device according to claim 1, wherein the trajectory changing means is configured to move a vehicle body-side mounting point of a suspension member to which a link supporting a wheel is mounted. 4. The suspension device according to claim 1, wherein said road surface shape detecting means is configured to detect at least one of a height and an inclination of a protrusion. 5. The trajectory changing unit according to claim 1, wherein the trajectory changing unit is configured to increase the tendency of the rear trajectory of the wheel center trajectory to increase as the road surface shape change detected by the road surface shape detecting unit increases. The suspension device according to any of the above. 6. The vehicle according to claim 1, wherein the trajectory changing means changes the trajectory of the wheel center as viewed from a side of the vehicle when the wheel passes through the protrusion so as to approach the vertical direction. The suspension device as described. 7. The trajectory changing means is configured to change the trajectory of the wheel center while maintaining a constant anti-pitching geometry during braking when changing the trajectory of the wheel center. The suspension device according to any one of the above.