JPH05319059A - Vehicle suspension device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a vehicle suspension system capable of obtaining sufficient vibration damping property even when the vehicle body is tilted due to a moment of inertia, thereby improving riding comfort and steering stability. A damping characteristic control means e having a basic control section d for controlling the damping characteristic of each shock absorber b based on a control signal obtained from the sprung vertical velocity, and a damping characteristic control means e. When the direction of the velocity and the direction of the sprung vertical velocity difference between the left and right of the vehicle body are the same direction, the control obtained by the sprung vertical velocity is a correction rate obtained from the product of the sprung vertical velocity difference and the sprung vertical velocity. When the roll correction control unit f that controls based on the control signal added to the signal and the damping characteristic control unit e are provided, and the direction of the sprung vertical velocity and the direction of the sprung vertical velocity difference before and after the vehicle body are the same direction. Is
A pitch correction control unit g is provided for controlling based on a control signal obtained by adding a correction rate obtained from the product of the sprung vertical velocity difference and the sprung vertical velocity to the control signal obtained from the sprung vertical velocity.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system for controlling a damping characteristic of a shock absorber, for example, Japanese Patent Laid-Open No. 61-
The thing described in 163011 gazette is known.
This conventional vehicle suspension system detects the sprung vertical speed and the relative speed between the sprung and unsprung parts, and when both have the same sign, the damping characteristic is made hard, and when the two have different signs, the damping characteristic is made soft. The four-wheel independent damping characteristic control based on the skyhook theory is performed.

[0003]

However, since the above-mentioned conventional apparatus has the above-mentioned configuration, when the hardware characteristic is suitable when the vehicle body is moving in the bounce direction, For the body motion in which bounce and roll or pitching are coupled, a moment of inertia of the body around the center of gravity of the body is added to the sprung mass,
There was a problem that the damping force (control force) was insufficient and the steering stability was poor.

There are also known devices for controlling rolls and pitches, but these are independent controls and require other sensors such as a steering sensor. It was also desired to simplify control and reduce the number of parts.

Further, in the damping characteristic control based on the skyhook theory, it is necessary to drive the actuator to switch the damping characteristic each time when the signs of both the sprung vertical velocity and the relative velocity are changed between coincidence and disagreement. Therefore, there is a problem that the control response is deteriorated, and the number of times the actuator is driven is increased, so that the durability is reduced.

The present invention has been made by paying attention to the above-mentioned conventional problems, and sufficient vibration damping property is obtained even with respect to the inclination of the vehicle body due to the moment of inertia, so that the riding comfort and the steering stability of the vehicle are improved. A first object is to provide a vehicle suspension device that can be improved, and a second object is to provide a vehicle suspension device that can simplify the configuration, improve control response, and improve durability of an actuator.

[0007]

In order to achieve the above-mentioned first object, the vehicle suspension system according to claim 1 of the present invention is as shown in FIG.
As shown in the claim correspondence diagram, the shock absorber b is interposed between the vehicle body side and each wheel side, and the damping characteristic can be changed by the damping characteristic changing means a, and the vicinity of the position where each shock absorber b is provided. A sprung vertical velocity detecting means c for detecting the sprung vertical velocity, and a damping characteristic control means e having a basic control section d for controlling the damping characteristic of each shock absorber b based on a control signal obtained from the sprung vertical velocity. When the direction of the sprung vertical speed and the direction of the left and right sprung vertical speeds of the vehicle body are the same in the damping characteristic control means e, the product of the sprung vertical speed difference and the sprung vertical speed is A roll correction controller f for controlling the damping characteristic of each shock absorber b based on a control signal obtained by adding the obtained correction rate to the control signal obtained from the sprung vertical velocity. .

In order to achieve the above-mentioned first object, the vehicle suspension system according to claim 2 of the present invention is interposed between the vehicle body side and each wheel side, and the damping characteristic is changed by the damping characteristic changing means a. A possible shock absorber b, a sprung vertical velocity detecting means c for detecting the sprung vertical velocity in the vicinity of the position where each shock absorber b is provided, and each shock absorber based on a control signal obtained from the sprung vertical velocity. b
And a damping characteristic control means e having a basic control section d for controlling the damping characteristic of the above, and the direction of the sprung vertical velocity and the direction of the sprung vertical velocity difference before and after the vehicle body are the same direction. At some time, the damping characteristic of each shock absorber b is controlled based on the control signal obtained by adding the correction rate obtained from the product of the sprung vertical velocity difference and the sprung vertical velocity to the control signal obtained from the sprung vertical velocity. And a pitch correction control unit g for performing the correction.

Further, in order to achieve the above-mentioned second object, in the vehicle suspension system according to a third aspect of the present invention, in addition to the above structure, the shock absorber is fixed to a variable damping characteristic on the extension side and a low damping characteristic on the compression side. The extension side hard area, the compression side hard area where the compression side has a variable damping characteristic and the extension side fixed to the low damping characteristic, and the soft area with both the extension side and the compression side have low damping characteristics When the control signal has a positive value, the characteristic control means controls the shock absorber in the expansion side hard area, when the control signal has a negative value, the shock absorber is controlled in the compression side hard area, and the control signal is 0. The shock absorber is controlled in the soft area.

[0010]

In the vehicle suspension system according to the first aspect, when the sprung speed detecting means detects the sprung vertical speed in the vicinity of the position where each shock absorber is provided, the basic control section of the damping characteristic control means The damping characteristic control of each shock absorber is performed based on the control signal obtained from the sprung vertical velocity. Then, when the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the left and right of the vehicle body are the same direction, the roll correction control unit obtains from the product of the sprung vertical speed difference and the sprung vertical speed. The damping characteristic control of each shock absorber is performed based on the control signal obtained by adding the correction rate to the control signal obtained from the sprung vertical velocity. Therefore, sufficient control force can be obtained not only for bounce but also for rolls of the vehicle body.

Further, in the vehicle suspension system according to claim 2,
When the sprung speed detecting means detects the sprung vertical speed in the vicinity of the position where each shock absorber is provided, the basic control unit of the damping characteristic control means detects the sprung vertical speed based on the control signal obtained from the sprung vertical speed. The damping characteristic control of each shock absorber is performed. When the direction of the sprung vertical speed and the direction of the sprung vertical speed difference before and after the vehicle body are the same direction, the pitch correction control unit obtains the product from the sprung vertical speed difference and the sprung vertical speed. The damping characteristic control of each shock absorber is performed based on the control signal obtained by adding the correction rate to the control signal obtained from the sprung vertical velocity. Therefore, sufficient control force can be obtained not only for bounce but also for the pitch of the vehicle body.

Further, in the apparatus according to the second aspect, when the control signal has a positive value, the shock absorber is controlled in the expansion side hard region (the compression side has a low damping characteristic fixed), and when the control signal has a negative value. The shock absorber is controlled in the compression side hard area (fixed to the low side damping characteristic), and when the control signal is 0, the shock absorber is controlled in the soft area. Therefore, the control signal based on the sprung vertical speed is used. When the relative speed between the sprung part and the unsprung part has the same sign, the stroke side of the shock absorber at that time is controlled to the hardware characteristic, and when the sign is different,
The same control as the damping characteristic control based on the skyhook theory, in which the stroke side of the shock absorber at that time is controlled to a soft characteristic, can be performed without detecting the relative speed between sprung and unsprung, and Since other sensors such as a steering sensor are not required, the structure can be simplified, and the switching of the damping characteristic toward the low damping characteristic direction is performed without driving the actuator. Compared with the damping characteristic control based on (1), the switching frequency of the damping characteristic is reduced, and the control response and the durability of the actuator can be improved.

[0013]

Embodiments of the present invention will be described with reference to the drawings. First, the configuration will be described. FIG. 2 is a configuration explanatory view showing a vehicle suspension device of an embodiment of the present invention, in which four shock absorbers SA are interposed between a vehicle body and four wheels.
₁ , SA ₂ , SA ₃ , and SA ₄ (when describing the shock absorber, when referring to these four collectively and when describing their common configuration, simply referred to as SA) are provided. ing. Further, a vertical acceleration sensor (hereinafter referred to as vertical G sensor) 1 for detecting vertical acceleration is provided near the mounting position of each shock absorber SA on the vehicle body. Further, a control unit 4 is provided near the driver's seat to input a signal from each sensor 1 and output a drive control signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above-mentioned configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c, and the interface circuit 4a is provided with the above-mentioned vertical G sensor 1. A signal is input. In addition, the interface circuit 4
In a, a low-pass filter for removing noise in a high frequency range (30 Hz or more) from the signal sent from the vertical G sensor 1, and the sprung vertical velocity Vn by integrating the acceleration signal passed through the low-pass filter. (Vn ₁ , Vn ₂ , Vn ₃ , V
A filter circuit 6 including a low-pass filter for converting into n ₄ ) is provided.

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. Which defines 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. A compression side damping valve 20 and an extension side damping valve 12 that open and close 31a and 31b respectively are provided. A stud 38 penetrating the piston 31 is screwed and fixed to a bound stopper 41 screwed to the tip of the piston rod 7. 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 pressure-side second flow path J, which will be described later) that connects the upper chamber A and the lower chamber B. A hole 39 is formed and the 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 provided on the outer peripheral portion of the communication hole 3 in accordance with 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 a fluid can flow in the extension stroke.
Open the inside of the extension side damping valve 12 through b and open 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 extension side third flow path F reaching 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
Channel H, hollow 19, first lateral hole 24, first port 21
The pressure-side second flow path J that opens the pressure-side check valve 22 to the upper chamber A via 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 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. 7, both the expansion side and the compression side are in the soft state (hereinafter, the soft region S
When the adjuster 40 is rotated counterclockwise from (S), the damping characteristic can be changed in multiple steps only on the extension side, and the compression side becomes a region where the low damping characteristic is fixed (hereinafter referred to as the extension side hard region HS). On the contrary, when the adjuster 40 is rotated clockwise, the damping characteristic can be changed in multiple steps only on the compression side, and the extension side becomes a region where the low damping property is fixed (hereinafter referred to as the compression side hard region SH). There is.

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

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

In step 101, the bounce signal V _BA , the roll signal V _RO and the pitch signal V _PI are obtained as follows. 16 is a time chart showing changes in sprung vertical velocities Vn ₁ and Vn _{2 at} the front wheel left and right positions and roll signals _FR V _RO and _FL V _RO , and FIG. 17 shows front wheel right and rear wheel right positions. 5 is a time chart showing changes in sprung vertical velocities Vn ₁ and Vn ₃ and pitch signals _FR V _PI and _RR V _PI . The sprung vertical velocities Vn (Vn ₁ , Vn ₂ , Vn ₃ , Vn ₄ ) are given as positive values in the upward direction and negative values in the downward direction.

(Bounce signal V _BA ) Front wheel Right _FR V _BA = Vn ₁ Front wheel Left _FL V _BA = Vn ₂ Rear wheel Right _RR V _BA = Vn ₃ Rear wheel Left _RL V _BA = Vn ₄ (Roll signal V _RO ) Front wheel Right _FR V _RO = Vn ₁ −Vn ₂ Front wheel Left _FL V _RO = Vn ₂ −Vn ₁ Rear wheel Right _RR V _RO = Vn ₃ −Vn ₄ Rear wheel Left _RL V _RO = Vn ₄ −Vn ₃ (Pitch signal V _PI ) Front wheel right _FR V _PI = Vn ₁ −Vn ₃ Front wheel left _FL V _PI = Vn ₂ −Vn ₄ Rear wheel right _RR V _PI = Vn ₃ −Vn ₁ Rear wheel left _RL V _PI = Vn ₄ −Vn ₂ Step 102 , The vehicle roll determination signal A (A ₁ , A ₂ , A ₃ ,
This is the step of obtaining A ₄ ). That is, in this step, it is determined whether the sprung vertical velocity Vn and the roll signal V _RO are in phase (indicated by the shaded area or meshed line in FIG. 16) or opposite phase, and the value of the roll component is calculated. To do.

Front wheel right A ₁ = Vn ₁ × _FR V _RO front wheel left A ₂ = Vn ₂ × _FL V _RO rear wheel right A ₃ = Vn ₃ × _RR V _RO rear wheel left A ₄ = Vn ₄ × _RL V _RO step Reference numeral 103 denotes a step of determining whether or not the roll determination signal A has a positive value (the phase of the sprung vertical velocity Vn and the phase of the roll signal V _RO are in phase). If YES (in phase), the process proceeds to step 104 and NO. In (reverse phase), the process proceeds to step 105.

In step 104, the roll components V _R ( _FR V _R , _FL V _R , _RR V _R , _RL V _R ) at each wheel are set to A (A ₁
, A ₂ , A ₃ , A ₄ ).

[0026] Step 105, the roll component V _R at each wheel _{(FR V R, FL V R} , RR V R, RL V R) which is a step of setting to zero.

In step 106, the vehicle roll judgment signal B (B
₁ , B ₂ , B ₃ , B ₄ ) These are the steps to obtain. That is,
In this step, it is determined whether the sprung vertical velocity Vn and the pitch signal _VPI are in phase (indicated by a shaded area or a meshed line in FIG. 17) or opposite in phase, and the value of the pitch component is calculated. Is.

Front wheel right B ₁ = Vn ₁ × _FR V _PI front wheel left B ₂ = Vn ₂ × _FL V _PI rear wheel right B ₃ = Vn ₃ × _RR V _PI rear wheel left B ₄ = Vn ₄ × _RL V _PI step 107 is a step of determining whether the pitch determination signal B is a positive value (sprung mass vertical velocity Vn phase with the phase of the pitch signal V _PI), the process proceeds to step 108 in YES (phase), NO In (reverse phase), the process proceeds to step 109.

In step 108, the pitch components V _P ( _FR V _P , _FL V _P , _RR V _P , _RL V _P ) at each wheel are set to B (B ₁
, B ₂ , B ₃ , B ₄ ).

Step 109 is a step for setting the pitch component V _P ( _FR V _P , _FL V _P , _RR V _P , _RL V _P ) of each wheel to zero.

Step 110 is a step for judging whether or not the sprung vertical velocity Vn is a positive value (shock absorber SA is in the stroke), and if YES (extension), the routine proceeds to step 111, and NO. In (pressure stroke), the process proceeds to step 112.

Step 111 is a step for obtaining the control signal V ( _FR V, _FL V, _RR V, _RL V) on the extension side based on the following equation. Front right _{FR V = α 1 · Vn 1} + β 1 · FR V R + γ 1 · FR
V _P Front Wheel Left _FL V = α ₁・ Vn ₂ ＋ β ₁・_FL V _R ＋ γ ₁・_FL
VP rear wheel right _RR V = α ₂ · Vn ₃ + β ₂ · _RR V _R + γ ₂ · _RR
V _P rear wheel left _{RL V = α 2 · Vn 4} + β 2 · RL V R + γ 2 · RL
V _P Note that α ₁ , β ₁ , γ ₁ are the proportional constants α ₂ , β ₂ , γ ₂ of the front wheels, and the proportional constants of the rear wheels, respectively.

In each equation, the first part bounded by α ₁ and α ₂ is the bounce rate, and β ₁ and β ₂
The part surrounded by is the roll rate, and γ ₁ , γ ₂
The part enclosed by is the pitch rate.

Step 112 is a step for obtaining the control signal V ( _FR V, _FL V, _RR V, _RL V) on the pressure stroke side based on the following equation. Front right _{FR V = α 1 · Vn 1} -β 1 · FR V R -γ 1 · FR
V _P front wheel left _{FL V = α 1 · Vn 2} -β 1 · FL V R -γ 1 · FL
V _P rear wheel right _{RR V = α 2 · Vn 3} -β 2 · RR V R -γ 2 · RR
V _P rear wheel left _{RL V = α 2 · Vn 4} -β 2 · RL V R -γ 2 · RL
The _VP step 113 is a step of determining whether or not the control signal V has a positive value (upward), and YES (upward).
To proceed to step 114, and NO (downward) to step 1
Proceed to 15.

Step 114 is a step of determining whether or not the previous control signal V _-1 has a negative value, and YES.
Then, the process proceeds to step 116, and if NO, the process proceeds to step 117. That is, in this step, it is determined whether or not the direction of the control signal V is reversed.

Step 116 is a step of initializing the threshold value V _S1 of the upward control signal V to a predetermined value.

Step 117 is a step of determining whether or not the control signal V has become _{equal to} or higher than a predetermined threshold value V _S1 , and if YES, the process proceeds to step 118, and if NO, step 1
Proceed to 19.

Step 118 is a step of updating the initially set threshold value V _S1 to the value of the control signal V at that time.

In step 119, the extension side target position Pn ( _FR Pn, _FL Pn, _RR Pn, _RL Pn) in the shock absorber SA is calculated based on the following formula, and the calculated target position Pn is set. This is a step of driving the pulse motor 3.

Front Wheel Right _FR Pn = (P _{+ MAX} / V _S1 ) × _FR V Front Wheel Left _FL Pn = (P _{+ MAX} / V _S1 ) × _FL V Rear Wheel Right _RR Pn = (P _{+ MAX} / V _S1 ) × _RR V Rear wheel left _RL Pn = (P _{+ MAX} / V _S1 ) × _RL V Step 115 is a step of determining whether or not the previous control signal V ₋₁ has a positive value, and if YES, step 1
20. If NO, the process proceeds to step 121. That is, in this step, it is determined whether or not the direction of the control signal V is reversed.

Step 120 is a step of initializing the threshold value V _S2 of the downward control signal V to a predetermined value.

In step 121, the absolute value of the control signal | V
Is a step of determining whether or not | is equal to or greater than the absolute value of a predetermined threshold value | V _S2 |
And proceeds to step 123 with NO.

Step 122 is a step of updating the initially set threshold value V _S2 to the value of the control signal V at that time.

In step 123, the pressure side target position Pn ( _FR Pn, _FL Pn, _RR Pn, _RL Pn) in the shock absorber SA is calculated based on the following formula, and the pulse is directed toward the calculated target position Pn. This is a step of driving the motor 3.

Front wheel right _FR Pn = (P- _MAX / V _S2 ) × _FR V front wheel left _FL Pn = (P- _MAX / V _S2 ) × _FL V rear wheel right _RR Pn = (P- _MAX / V _S2 ) × _RR V rear wheel left _{RL Pn = (P -MAX / V} S2) × RL V or more and completes one control flow, thereafter those repeating the above control flow.

Next, the operation of the embodiment apparatus will be described with reference to the time chart of FIG. In the drawing, the control signal V, the damping force F and the relative speed, the control direction (stroke) of the shock absorber SA, and the target position Pn are shown in order from the top, and the control signal V draws a sine curve and extends.
The figure shows the case where the pressure side alternates, and the peak values P ₁ and P _{2 change} in the vertical direction so as to exceed the threshold values V _S1 and V _S2 of the initial setting values, respectively.

In the figure, a region a is a region in which the control signal V is upward and is less than the initial threshold value V _S1 . In this case, the maximum damping position P at the value of the initial threshold value V _S1
The target position P on the extension side, which is the target, so as to be _{+ MAX}
n will be controlled in proportion to the control signal V.

The next region b is a region in which the control signal V becomes equal to or higher than the initial threshold value V _S1 and reaches the peak value P ₁ , and in this case, according to the flow of steps 117 to 118 in FIG. As a result of performing the process of matching the threshold value V _S1 with the control signal V at all times, the target position Pn on the extension side is held at the maximum attenuation position P _{+ MAX} on the extension side until the peak value P ₁ is reached.

In the next area c, the control signal V has a peak value P ₁
From the point where the direction of the control signal V reverses,
In this case, since the threshold value V _S1 is also equal to the peak value P ₁ when the control signal V reaches the peak value P ₁ , the control signal V is calculated based on the arithmetic expression shown in step 119 of FIG. Is lower than the peak value P ₁ , the target position Pn on the extension side decreases from that point in proportion to the decrease of the control signal V.

The next area d is an area from when the direction of the control signal V is reversed to when it becomes the downward downward threshold value V _S2 or more. In this case, the target position Pn on the pressure side is controlled in proportion to the control signal V so that the maximum damping position P _-MAX is obtained at the value of the initial threshold value V _S2 .

The next area e is an area until the control signal V becomes equal to or more than the initial threshold value V _S2 and reaches the peak value P ₂ , and in this case, according to the flow of steps 121 to 122 in FIG. As a result of performing the process of matching the threshold value V _S2 with the control signal V at all times, the target position Pn is held at the compression side maximum damping position P _-MAX until the peak value P ₂ is reached.

In the next area f, the control signal V has a peak value P ₂
From the point where the direction of the control signal V reverses,
In this case, when the control signal V reaches the peak value P ₂ , it becomes equal to the threshold value V _S2 peak value P _2, and therefore, based on the arithmetic expression shown in step 123 of FIG.
When the control signal V changes upward from the peak value P ₂ , the target position Pn on the extension side decreases from that point in proportion to the change in the control signal V.

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

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

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

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

As described above, in this embodiment, when the control signal V based on the sprung vertical velocity and the relative velocity between the sprung and unsprung portions have the same sign (region h, region k), the shock at that time is generated. Damping characteristic control based on the skyhook theory, in which the stroke side of the absorber SA is controlled to have a hard characteristic, and when the shock absorber SA has a different sign, the stroke side of the shock absorber SA at that time is controlled to have a soft characteristic. The same control as above will be performed without detecting the relative speed between the sprung and unsprung parts. Further, in this embodiment, when the region g is shifted to the region h and the region j is shifted to the region k, the damping characteristic is switched without driving the pulse motor 3.

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

In performing the damping characteristic control based on the skyhook theory in consideration of the roll and the pitch as described above, only the upper and lower G sensors are used as the detection means, so that the number of parts can be reduced and the cost can be reduced. At the same time, the labor, assembling space and weight of assembling can be reduced.

Compared with the conventional damping characteristic control based on the skyhook theory, the frequency of switching the damping characteristics is reduced, so that the control response can be improved and the durability of the pulse motor 3 can be improved.

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

For example, in the embodiment, the control content is such that the stroke of the one controlling to the hardware characteristic side is determined depending on whether the sprung vertical velocity is a positive value or a negative value. A value is provided, and while the sprung vertical velocity is within this positive / negative threshold, the soft region SS is controlled so that both the extension side and the compression side have soft characteristics, and when the positive / negative threshold is exceeded, the hard characteristic (extension It is also possible to control to the side hard region HS or the pressure side hard region SH) side.

Further, in the embodiment, the target position is calculated based on the arithmetic expression, but it may be calculated based on the map shown in FIG. In this figure, (a) is a map for extension side and (b) is a map for compression side, and the target position P corresponding to the value of the control signal V is shown.
n is set.

The bounce signal V _BA , the roll signal V _RO and the pitch signal V _PI can also be obtained based on the following formulas.

(Bounce signal V _BA, other example 1) Front wheel right / left _FR V _BA , _FL V _BA = (Vn ₁ + Vn ₂ ) / 2 rear wheel right / left _RR V _BA , _RL V _BA = (Vn ₃ + Vn ₄ ) / 2 (Bounce signal V _BA Other example 2) Front / rear wheel right / left V _BA = (Vn ₁ + Vn ₂ + Vn ₃ + Vn ₄ )
/ 4 (roll signal V _RO other example) Right wheel front and rear _FR V _RO , _RR V _RO = (Vn ₁ + Vn ₃ ) / 2-
(Vn ₂ + Vn ₄ ) / 2 Left wheel front / rear _FL V _RO , _RL V _RO = (Vn ₂ + Vn ₄ ) / 2-
(Vn ₁ + Vn ₃ ) / 2 (Pitch signal V _PI other example) Front wheel right / left _FR V _PI , _FL V _PI = (Vn ₁ + Vn ₂ ) / 2-
(Vn ₃ + Vn ₄ ) / 2 Rear wheel right / left _RR V _PI , _RL V _PI = (Vn ₃ + Vn ₄ ) / 2
(Vn ₁ + Vn ₂ ) / 2 In this embodiment, when one side of both the extension and compression strokes is controlled to the high damping characteristic side, the reverse stroke side is fixed to a predetermined low damping characteristic. Although a shock absorber having a structure is used, a shock absorber having a structure in which both expansion and compression strokes change at the same time can be used.

In this embodiment, the control signal is obtained based on the bounce rate, the pitch rate and the roll rate.
Alternatively, the control signal can be obtained based on the bounce rate and the roll rate.

[0067]

As described above, the present invention claims 1.
In the vehicle suspension device described above, when the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the left and right of the vehicle body are the same direction, the correction is obtained from the product of the sprung vertical speed difference and the sprung vertical speed. The roll correction controller that controls the rate based on the control signal that is added to the control signal obtained from the sprung vertical velocity provides sufficient vibration suppression not only for bounce but also for the roll of the vehicle body by steering operation. The ride quality is improved, and the ride comfort and driving stability can be improved.

In the vehicle suspension system according to the second aspect of the present invention, when the direction of the sprung vertical velocity and the direction of the sprung vertical velocity difference between the front and rear of the vehicle body are the same direction, the sprung vertical velocity difference and the spring velocity. By providing the pitch correction control unit that controls based on the control signal obtained by adding the correction rate obtained from the product of the upper and lower speeds to the control signal obtained from the sprung vertical speed, not only the bounce but also the vehicle body by the steering operation. Sufficient vibration damping performance can be obtained even for the pitch of, and this has the effect of improving the riding comfort and steering stability.

In addition to the above structure, the vehicle suspension system according to a second aspect of the present invention includes, in addition to the above-mentioned structure, each of the shock absorbers, an extension side hard region in which the extension side has a variable damping characteristic and the compression side has a low damping characteristic.
The damping side is formed in a structure having three regions, a compression side hard region where the damping characteristic is variable and the expansion side is fixed to the low damping characteristic, and a soft region where both the expansion side and the compression side have low damping characteristics, and the damping characteristic control means is controlled. When the signal is above the positive threshold, the shock absorber is controlled in the expansion side hard area, and when the control signal is below the negative threshold, the shock absorber is controlled in the compression side hard area, and the control signal is positive / negative. By configuring the shock absorber to control in the soft region when it is between the threshold values, it is possible to control the damping characteristics based on the skyhook theory without using the relative speed detection means, and reduce the number of parts. And cost reduction, as well as assembly work,
Assembling space and weight can be reduced, and the damping characteristic switching frequency can be reduced compared to the conventional damping characteristic control based on the skyhook theory, so that the control response can be improved and the damping characteristic switching actuator The effect that the durability of can be improved can be obtained.

[Brief description of drawings]

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

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

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

FIG. 4 is a cross-sectional view showing a shock absorber applied to the apparatus of the embodiment.

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

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

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

FIG. 8 is a part of the shock absorber shown in FIG.
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 pressure side hard state.

FIG. 14 is a flowchart showing a control operation of a control unit in the apparatus of the embodiment.

FIG. 15 is a time chart showing the control operation of the control unit in the apparatus of the embodiment.

FIG. 16 is a time chart illustrating a method for determining a roll occurrence state in the apparatus of the embodiment.

FIG. 17 is a time chart illustrating a method of determining a pitch occurrence state in the device of the embodiment.

FIG. 18 is a map showing another example of how to obtain a target position.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical velocity detecting means d basic control section e damping characteristic control means f roll correction control section g pitch correction control section

Claims (3)

[Claims] 1. A shock absorber which is interposed between a vehicle body side and each wheel side and whose damping characteristic can be changed by a damping characteristic changing means, and a sprung vertical velocity in the vicinity of the position where each shock absorber is provided is detected. A sprung vertical velocity detection means, a damping characteristic control means having a basic control unit for controlling the damping characteristic of each shock absorber based on a control signal obtained from the sprung vertical velocity, and the damping characteristic control means When the direction of the sprung vertical velocity and the direction of the sprung vertical velocity difference between the left and right of the vehicle body are the same direction, the correction rate obtained from the product of the sprung vertical velocity difference and the sprung vertical velocity was obtained from the sprung vertical velocity. A vehicle suspension device comprising: a roll correction control unit that controls a damping characteristic of each shock absorber based on a control signal added to the control signal. 2. A shock absorber, which is interposed between the vehicle body side and each wheel side and whose damping characteristic can be changed by the damping characteristic changing means, and a sprung vertical velocity near the position where each shock absorber is provided is detected. A sprung vertical velocity detection means, a damping characteristic control means having a basic control unit for controlling the damping characteristic of each shock absorber based on a control signal obtained from the sprung vertical velocity, and the damping characteristic control means When the direction of the sprung vertical velocity and the direction of the sprung vertical velocity difference before and after the vehicle body are the same direction, the correction rate obtained from the product of the sprung vertical velocity difference and the sprung vertical velocity was obtained from the sprung vertical velocity. A vehicle suspension device comprising: a pitch correction control unit that controls a damping characteristic of each shock absorber based on a control signal added to the control signal. 3. The shock absorber includes an expansion side hard region in which the expansion side is variable in damping characteristic and the compression side is fixed in low damping characteristic, and a compression side hard region in which the compression side is variable in damping characteristic and expansion side is fixed in low damping characteristic is expanded. It is formed in a structure having three regions, a soft region having a low damping characteristic on both the pressure side and the compression side, and the damping characteristic control means controls the shock absorber in the expansion side hard region when the control signal has a positive value. The shock absorber is controlled in the pressure side hard region when the signal has a negative value, and the shock absorber is controlled in the soft region when the control signal is 0.
Alternatively, the vehicle suspension device according to claim 2.