JPH02296524A - Stabilizer for vehicle - Google Patents

Abstract

PURPOSE:To secure high groundability by installing a hydraulic cylinder interposingly between an antiroll bar and a car body and so on, and controlling it according to lateral acceleration, in a device which is equipped with this antiroll bar generating torsional reaction according to a difference in vertical motion of symmetrical wheels. CONSTITUTION:A vehicle stabilizer 6 being installed in front and rear wheels is provided with almost U-shaped antiroll bars 10F, 10R being installed between wheel side members (suspension arms) 22 as an unspringing member moving up and down together with longitudinal symmetrical wheels 4 (4FL-4RR) being installed in a car body 2. In this case, each pair of hydraulic cylinders 12 (12FL-12RR) are installed between these antiroll bars 10F, 10R and the car body 2. Pressure oil out of a hydraulic source 20 is fed to each hydraulic cylinder 12 via respective pressure control valves 14L, 14R, while each of these pressure control valves 14L, 14R is controlled by output of a lateral acceleration sensor 18 via a controller 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes an anti-roll bar whose both ends are attached to unsprung members of a suspension and whose middle section is attached to be supported by a vehicle body. The present invention relates to an improvement in a stabilizer for a vehicle in which a bar is twisted in accordance with the difference in vertical motion between left and right wheels, thereby generating torsional rigidity, or so-called torsional reaction force.

[Conventional technology]

As a conventional vehicle stabilizer, for example, the one described in Japanese Patent Application Laid-open No. 169314/1988, which has already been proposed by the applicant of the present invention, is known.

In this conventional vehicle stabilizer, hydraulic cylinders are interposed at the vehicle body support points of the anti-roll bar, and the upper and lower cylinder chambers of the hydraulic cylinders are controlled according to the working oil pressure of the power steering or the yaw rate or lateral acceleration of the vehicle. The structure is such that controlled hydraulic pressure is introduced, and the stroke of the hydraulic cylinder is expanded or contracted by this hydraulic pressure. Therefore, as the cylinder stroke expands and contracts, the cylinder connecting portion of the anti-roll bar is lifted up or down or pushed down, thereby generating a large torsional reaction force on the anti-roll bar, thereby suppressing the roll.

[Problem to be solved by the invention]

However, in such conventional vehicle stabilizers, the hydraulic pressure controlled according to the working hydraulic pressure of the power steering or the vehicle's yaw rate or lateral acceleration is guided to the hydraulic cylinder, so there is no space inside the hydraulic cylinder. Although it is possible to control the roll of the vehicle because it is filled with pressure oil that corresponds to the steering force of the power steering or the lateral acceleration, the cylinder locks when performing roll control such as when turning on a large uneven road surface. Since the stabilizer remains in this state, the torsional torque (torsional reaction force) of the stabilizer becomes large, and the spring constant of the suspension becomes large.

Therefore, the unevenness of the road surface is directly transmitted to the vehicle body, causing the vehicle body to be vibrated up and down, which impairs the ride comfort during turning.In addition, if the lateral acceleration is large, the ground contact is lost, and the vehicle is There was an unresolved issue of worsening stability.

The present invention has been made by focusing on such conventional unsolved problems, and is capable of accurately suppressing roll and maintaining a flat posture when controlling roll during turning, etc. on a road surface with large unevenness. The problem that the vehicle is trying to solve is to reliably attenuate the vibrations that are transmitted from the road side to the vehicle body side to maintain a good ride comfort, and to improve driving stability by increasing ground contact. .

[Means to solve the problem]

In order to solve the above-mentioned problems, the invention of this application has both ends attached to the unsprung members of the suspension, and the middle section attached to be supported by the vehicle body, so that the torsional reaction is achieved according to the difference in the vertical movement of the left and right wheels. In a vehicle stabilizer equipped with an anti-roll bar that generates force, a fluid pressure cylinder is interposed between the anti-roll bar and an unsprung member of the vehicle body or suspension, and the operating pressure of this fluid pressure cylinder can be changed. A pressure control valve that controls only according to a command value, a lateral acceleration detection means that detects lateral acceleration generated in the vehicle body, and a command value calculation that calculates a command value according to the lateral acceleration detected value of the lateral acceleration detection means. The main point is that the means have been established.

[Effect]

In the invention of this application, since almost no lateral acceleration occurs when traveling straight, the command value by the command value calculation means is a value corresponding to zero lateral acceleration, and the stroke amount of the fluid pressure cylinder is determined by this command value. , the anti-roll bar cannot be twisted. Therefore, when the left and right wheels are twisted in opposite phases due to random irregularities on the road surface while driving straight ahead, a roll reaction force is obtained due to the torsional rigidity of the anti-roll bar, and the roll reaction force due to the irregularities is obtained. Lateral vehicle body fluctuations are suppressed.

Also, when turning, etc., the command value calculation means calculates a command value according to the detected lateral acceleration value, and the pressure control valve controls the pressure of the left and right fluid pressure cylinders in opposite phases based on the command value. By actively twisting the anti-roll bar and controlling the force at the vehicle body support point or suspension attachment point of the bar, a roll reaction force is generated and roll is suppressed. At this time, when low-frequency vibration input due to unevenness of the road surface is input to the wheels, the pressure fluctuation in the cylinder chamber due to this vibration is directly fed back to the pressure control valve, and the fluctuation is absorbed by the pressure control valve, so that the cylinder pressure is always held at a value corresponding to the command value. In other words, even when roll is suppressed, vibrations transmitted to the vehicle body can be reduced.

〔Example〕

Hereinafter, embodiments of the invention of this application will be described with reference to the drawings.

(First example) A first embodiment is shown in FIGS. 1 to 5.

In Fig. 1, 2 is the vehicle body, 4FL to 4RR are front to rear right wheels, and 6 is front wheels 4FL, 4FR, rear wheels 4RL, 4.
A vehicle stabilizer provided for RRL is shown.

In this embodiment, the vehicle stabilizer 6 is an anti-roll bar 10F on the front side 5 and the rear side of the vehicle.

■Hydraulic cylinder 12 as a fluid pressure cylinder installed for OR and front anti-roll bar 10F
PL, 12PR and rear anti-roll bar 1O
Hydraulic cylinders 12RL and 12RR as fluid pressure cylinders equipped for R, and hydraulic cylinder 12FL.
~12RR, two pressure control valves 14L and 14R are installed corresponding to the left and right two sets, respectively, and this pressure control valve 1
A hydraulic power source that includes at least a controller 16 as a command value calculation means for controlling 4L and 14R, a lateral acceleration sensor 18 as a lateral acceleration detection means for detecting lateral acceleration generated in the vehicle body, a hydraulic pump 20A, and a reservoir tank 20B. 20.

The left and right front wheels 2PL and 2RR are suspended on the vehicle body 2 by a well-known suspension (not shown).
The substantially U-shaped anti-roll bar 10F is attached between the wheel-side members (suspension arms) 22 as unsprung members that move up and down together with the 2RR. In this embodiment, the left and right rear wheels 2RL, 2RR are suspended on the vehicle body 2 by a parallel link strut type suspension, and the rear wheels 2RL, 21? The substantially U-shaped anti-roll bar 1OR is attached between the wheel-side members 24 as unsprung members that move up and down with R, as on the front side. In addition, the front wheels 10PL and 10FR have a steering wheel 26, a rack and pinion type steering gear 27, and a steering linkage 28L, 2
Steering is possible via 8R. In the figure, 29.30
is a lateral rod.

Each of the hydraulic cylinders 12FL to 12RR is a single-acting type as shown in FIG.
A piston 1 connected to a piston rod 12b in a
2c is slidably inserted into the cylinder chamber S.
R is spaced on one side, and this cylinder chamber S
It has a structure in which a spring 12d that biases the piston 12c is inserted into the tube 12a on the opposite side of R (actually, each cylinder 12FL to 12RR is installed in an upright state with the cylinder tube 12a on the upper side. ).

And the front side hydraulic cylinders 12FL, 12FR
Each of the piston rods 12b is rotatably attached to the bar 1 via an elastic bushing 32 at two vehicle body attachment points at the center portion (middle portion) in the vehicle width direction of the anti-roll bar 10F.
By supporting the bar 10F and attaching the cylinder tube 12a to the vehicle body 2, it is disposed between the bar 10F and the vehicle body 2. Rear hydraulic cylinder 12RL, 12RR
Similarly to the front side, each of the anti-roll bar 1OR is disposed between the bar 1OR and the vehicle body 2 at two points where the anti-roll bar 1OR is attached to the vehicle body.

In this embodiment, the front side hydraulic cylinder 12P
The effective pressure receiving areas of L and 12FR are set larger than those of rear hydraulic cylinders 12RL and 12RR.

In addition, each of the pressure control valves 14L and 14R is conventionally known (
For example, see Japanese Patent Application Laid-Open No. 187609/1983), the valve is composed of a 3-port proportional electromagnetic pressure reducing valve, and as shown in FIG. have.

Among these, a spool 44 with a spring 42 interposed therebetween and a rod 46 are slidably disposed in an insertion hole 38a formed in the center of the valve housing 38, and a land 44a of the spool 44, A supply boat 38s and a return port 38r are formed at a position opposite to land 44b, and an output port 38o is formed at a position opposite to the intermediate portion of both lands 44a, 44b. The spool 44 has both lands 44a at its lower end opposite to the proportional solenoid 40.
, 44b, and has a land 44c having a smaller diameter than that of land 44b.
A pressure control chamber C is formed between the land 44c and the land 44c.

The return port 38r communicates with the upper and lower ends of the spool 44 via the drain passage 38A, and the output port 38o communicates with the pressure control chamber C via the feedback passage 38B.

In addition, the supply port 38s and the return port 38r are connected to the piping 4.
8.49 to the discharge side and drain side of the hydraulic power source 20, and the output port 380 is connected to the cylinder chamber SR of the hydraulic cylinder 12FL (~121?R) via the piping 50. In the entire vehicle, the cylinder chambers SR of the cylinders 12PL and 12RL on the left side of the vehicle are commonly connected to the output port 380 of the left pressure control valve 14L, and the cylinder chambers SR of the cylinders 12PR and 12IIR on the right side of the vehicle are connected to the right pressure control valve 14L. Output port 380 of control valve 14R
are commonly connected.

On the other hand, the proportional solenoid 40 includes an actuator 40a that is slidable in the axial direction and an excitation coil 40b that drives the actuator 40a, and has a command value I that is a current value output from the controller 16, which will be described later. Drive controlled by. That is, the pressing force of the spring 42 is controlled via the rod 46 in accordance with the value of the command value r, and the position of the spool 44 is controlled to move between the offset position and the operating positions at both ends thereof.

Here, the relationship between the command value 1 and the operating pressure P output from the output port 38o is as shown in FIG.

That is, the pressure P is a predetermined offset pressure P when the command value I is zero. From this state, the command value I changes proportionally (into a proportional gain), and the hydraulic pressure source 2
When the line pressure P2 of 0 is reached, it is saturated.

For this reason, the pressing force of the proportional solenoid 40 is applied to the spool 44 via the spring 42, and in a state where the pressing force of the spring 42 and the pressure of the pressure control chamber C are balanced, the wheel is pressed against a bump on the road surface, for example. When a relatively low frequency vibration input corresponding to the upward sprung mass resonance frequency due to passage through the recess (or downward vibration input due to passage through the recess) is transmitted, this causes the piston rod 12b of the hydraulic cylinder 12FL (~12RR) to move upward. (or downward), and the pressure in the pressure chamber SR increases (or remains). In response to this, the pressure in the pressure control chamber C on the control valve 14L (14R) side increases (or decreases), and the balance with the pressing force of the spring 42 is disrupted, so the spool 44 moves upward (or downward). , in the direction in which the gap between the supply port 38s and the output port 38o is closed (or in the direction in which it is opened), and in the return port 3
The direction between 8r and the output port 380 changes in the direction in which it is opened (or in the direction in which it is closed). As a result, the cylinder chamber S
A portion of the hydraulic fluid R is discharged to the hydraulic source 20 (or the hydraulic fluid is supplied from the hydraulic source 20 to the cylinder chamber SR).

As a result, the working pressure of the hydraulic cylinder 12FL (~1211R) is reduced (or increased), and the pressure increase in the cylinder chamber SR due to upward vibration input (or pressure decrease due to downward vibration input) is suppressed. The vibration input transmitted to the vehicle body 2 can be accurately reduced.

On the other hand, the lateral acceleration sensor 1B is installed, for example, at the center of gravity of the vehicle body, and detects acceleration in the lateral direction (vehicle width direction) that occurs in the vehicle body during turning or slalom running, and generates a voltage signal corresponding to the acceleration. Transverse acceleration signal y is sent to controller 1
6. The lateral acceleration sensor 18 in this embodiment is set to output a positive detection signal y when lateral acceleration to the left occurs with respect to the running direction, and a negative detection signal y when lateral acceleration occurs to the right. There is.

In this embodiment, as shown in FIG. 4, the controller 16 includes a gain adjuster 56 that calculates a command value V consisting of a voltage value by multiplying the lateral acceleration detection signal y by a fixed gain Ka;
A sign inverter 57 that multiplies "-1" and a sign inverter 57 that converts the command values ■ and ■ into current values and controls the left and right pressure control valves 14L and 14R.
A drive circuit 58.5 outputs to each proportional solenoid 40 of
9.

Next, the operation of the above embodiment will be explained.

Assuming that the vehicle is currently traveling straight at a constant speed on a good road with no major irregularities, no lateral acceleration will occur in this traveling state.

Therefore, the lateral acceleration detection signal y becomes zero, and the command value (,
Since ■ is both zero, the left and right pressure control valves 14L,
14R sets the offset pressure P0 to the left hydraulic cylinder 12.
PL, 12RL and right hydraulic cylinder 12FR,
12RR respectively. Therefore, in each of the hydraulic cylinders 12FL to 12RR, a stroke amount is set so that the force based on the offset pressure P0 (=P0 effective pressure receiving area) and the spring force of the spring 12d are balanced. In this state,
Anti-roll bar 10F, IOR is not working, so
The spring constant of the suspension is therefore small, allowing it to absorb even the slightest unevenness, providing a comfortable ride.

Further, suppose that the vehicle continues to travel straight and reaches a road surface with relatively large (low frequency) and random irregularities. Due to this unevenness, the left and right wheels are 4FL, 4RL, and 4FR.

When 4RR moves up and down in the opposite phase, cylinders 12FL to 2
Anti-roll bar IO against spring 12d of RL
F and IOR are twisted, and roll rigidity is increased by the torsional rigidity of the bars 10F and 10R themselves, and lateral rocking due to unevenness can be suppressed.

Furthermore, suppose that the vehicle is turned from the above-mentioned constant-speed straight-ahead state to make a left turn, for example, on a road surface with relatively large and random irregularities. As a result, a lateral acceleration is generated in the right lateral direction according to the vehicle speed and the turning angle, and this acceleration causes an inertial force (centrifugal force) F.
occurs to the right as shown in Figure 5 (schematically representing the state seen from the front of the vehicle; the same applies to Figure 7.10 below), and the outer wheels 4FR and 4RR of the vehicle body 2 sink, causing the inner wheel 4F to sink.
L, JRL side is trying to rise.

However, the lateral acceleration sensor 18 detects the generated lateral acceleration and sends a negative value signal y corresponding to the lateral acceleration to the controller 1.
6, the controller 16 performs the above calculation, and
A negative command value I is output to the left pressure control valve 14L, and a positive command value ■ is output to the right pressure control valve 14R. As a result, the hydraulic cylinders 12FL and 121'l on the left side of the vehicle
P<P for L. The working pressure P is supplied to the hydraulic cylinders 12PR and 12RR on the right side of the vehicle, and P > P o
Since the working pressure P is supplied, the hydraulic cylinder 1 on the outer ring side
In 2FR and 12RR, the force based on the increased working pressure P becomes larger than the spring force of the spring 12d, and the stroke amount of both cylinders 12FL and 12RL increases, and in the inner hydraulic cylinders 12FL and 12RL, the operation decreases. The force based on the pressure P becomes smaller than the spring force of the spring 12d, and the stroke amount of both cylinders 12FL and 12RL is reduced, resulting in the state shown in FIG. 5.

This expansion and contraction of the stroke amount is performed against the torsional rigidity of the front and rear anti-roll bars 10F and IOR, and the bars 10F and IOR are twisted. Therefore, an upward force acts on the outer ring side and a downward force acts on the inner ring side at the cylinder connection point of the bar 10F and IOR. For this reason, a roll reaction force is generated that resists the force of the outer wheel side to sink and the force of the inner wheel side to rise, and by controlling the force of the inner and outer wheels, the vehicle body is supported in a substantially flat state.

It is also assumed that a relatively low frequency vibration (frequency in the sprung mass resonance frequency range) is input from the road surface by passing through the uneven portion. With this vibration input, as mentioned above,
Hydraulic cylinder 12FL~121? Although the operating pressure of R fluctuates, these pressure fluctuations become the same pressure between the front and rear operating pressures of the vehicle that are in communication, and the pressure control valve 14L corresponds as necessary.

The 14R spool 44 is moved in the axial direction as described above. As a result, the hydraulic cylinders 12PL-12R are controlled via the pressure control valves 14L and 14R until the working pressure P of the hydraulic cylinders 12FL-12RR becomes a pressure corresponding to the command value I.
1? Hydraulic oil flows between the hydraulic power source 20 and the hydraulic power source 20, and vibration input is accurately damped and absorbed.

The above control operations when turning are completely the same when turning left.

In this way, in this embodiment, the cylinder operating pressure, which was conventionally generated by the power steering operation valve, switching valve, etc.
Pressure control valves 14L, 14 that convert pressure according to lateral acceleration
R is used, and the cylinder operating pressure P is directly fed back to the pressure control valves 14L and 14R, so that the operating pressure is always maintained at a value corresponding to the command value. Therefore, even if the anti-roll bar 10F and IOR are actively twisted during cornering, etc. to increase the roll reaction force and control the spring constant of the suspension to be high, vibration input will be applied to the vehicle body 2 due to large irregularities on the road surface. It reliably reduces the amount of vibration transmitted to the vehicle, suppresses the vertical vibration of the vehicle body, maintains good ride comfort, and eliminates the loss of ground contact unlike conventional models even when lateral acceleration is large. , driving stability can be improved.

Also, during the roll control, anti-roll bars 10F and I
The force that twists the OR is greater on the front side than on the rear side due to the difference in effective pressure receiving area within the hydraulic cylinders 12FL to 12RR, and therefore the roll reaction force is also greater on the front side. As a result, the share of roll stiffness becomes larger on the front side than on the rear side, so that the steering characteristics tend to understeer, and the vehicle running characteristics become stable. In addition,
In order to obtain this advantage, a structure in which the mounting points of the hydraulic cylinders 12FL to 12RR are different on the front and rear sides can be adopted instead of the structure in which the effective pressure receiving area is differentiated.
Considering constraints on vehicle layout, it is more advantageous to adopt the former structure for normal vehicles.

Furthermore, in this embodiment, the front and rear hydraulic cylinders 12PL,
Since 12RL, 12FIl, and 12RR form a pair, a total of two pressure control valves 14L and 14R are required, which has the advantage of simplifying the overall configuration.

Furthermore, even if there is a large flow rate change, that is, a low frequency vibration input from the road surface when traveling straight, the hydraulic cylinder 12FL has the above-mentioned vibration absorbing effect.
There is no indication that the vibration transmission rate to the vehicle body will increase due to the installation of ~12RR.

(Second Embodiment) Next, a second embodiment will be described based on FIGS. 6 and 7. Here, the same reference numerals are given to the same components as in the first embodiment described above.

This second embodiment is based on the hydraulic cylinder 1 in the first embodiment.
This is a 2FL-12RR with a different equipment location. Specifically, as shown in FIG. 6, the hydraulic cylinders 12FL~
12RR with front and rear anti-roll bars 10F
, are interposed between the end of the IOR and the wheel side members 22, 24, which are unsprung members of the suspension. The other configurations are the same as in the first embodiment.

As a result, as in the first embodiment, force control can be performed on the front and rear anti-roll bars 10F and IOH. For example, when the vehicle turns left and lateral acceleration occurs in the right lateral direction, the outer wheel The right hydraulic cylinder 12 is
FI? , l The operating pressure of 2RR is higher than the offset pressure P0, and the left hydraulic cylinder 12F, which is the inner ring side,
The operating pressure of L and 12RL is lowered. Therefore, the seventh
As shown in the figure, the hydraulic cylinders 12FR, 12 on the outer ring side
RR is extended and the inner ring side hydraulic cylinder I 2PL
, 12RL is reduced, anti-roll bar 10F,
The IOR is twisted in the opposite direction to the first embodiment. Therefore, a roll reaction force is generated in advance that opposes the force that causes the outer ring side to sink and the inner ring side to rise, resulting in a flat roll state.

On the other hand, when driving straight at a constant speed, if there is vibration input due to relatively large and random irregularities on the road surface, each of the hydraulic cylinders 12FL to 12RL absorbs pressure fluctuations in the same way as in the first embodiment. When you can't do it anymore,
Anti-roll bar 10F.

10R is twisted. In other words, the torsional rigidity of the bars 10F and 10R can suppress lateral vehicle body fluctuations caused by unevenness.

In this way, the second embodiment can also obtain the same effects as the first embodiment, and the cylinder 12FL
~12RL equipment position is anti-roll bar 10F, IO
Since there are suspension mounting points for R, it has the advantage of being easy to install and being easy to mount on a vehicle.

In each of the embodiments described above, the left and right sides are controlled independently, but the present invention is not necessarily limited to this. For example, four hydraulic cylinders 12F to 12R are controlled independently.
Four individual pressure control valves are provided corresponding to R, and each cylinder 12FL to 121? R may be independently controlled.

(Third Embodiment) Next, a third embodiment will be described based on FIGS. 8 to 10. Here, the same reference numerals are used for the same components as in each of the above embodiments.

In this third embodiment, the suspension attachment points of the anti-roll bar 10F and IOR are force-controlled as in the second embodiment, but only the attachment points on the left side of the vehicle are actively controlled.

Specifically, double-acting hydraulic cylinders 62FL and 62RL are installed between the front left and rear left wheel side members 22 and 24 and the ends of the anti-roll bar 10F and IOR, respectively, as shown in FIG. The front cloth side and rear right wheel side members 22, 24 and the ends of the anti-roll bar 10F and IOH are rigidly connected by connecting rods 64, 64, respectively. This connecting rod 64.
The length of the cylinder 64 is adjusted to the stroke amount taken by the hydraulic cylinders 62FL and 62RL when the vehicle travels straight at a constant speed on a good road. Furthermore, the hydraulic cylinder 62FL.

The operating pressure of 62RL is controlled by a direction control valve 66 serving as an independent pressure control valve.

Hydraulic cylinder 62FL, 621? Each of L has its cylinder tube 62a connected to the anti-roll bar 10F (I
The piston rod 62b has a structure in which the lower end of the piston rod 62b is attached to the wheel side member 22 (24). The cylinder tube 62a is defined into a lower pressure chamber A and a lower pressure chamber B by a piston 62c attached to the lower end of a piston rod 62b extending into the cylinder tube 62a.

The directional control valve 66 is a conventionally well-known 4-port valve (for example, see Japanese Patent Laid-Open No. 193910/1983), and as shown in FIG. It has a spool 75 that is movably arranged, and a proportional solenoid 76 that controls the movement of the spool 75 between a neutral position and offset positions on both ends thereof.

The valve housing 74 has supply ports 74a, 74 connected to the hydraulic oil supply side of the hydraulic power source 20 via hydraulic piping 78.
b, a return bow 1-74c connected to the drain side of the hydraulic power source 20 via a hydraulic pipe 79, and a hydraulic cylinder 62FL.
Hydraulic piping 80 for each pressure chamber A of (62RL) and
and output port doors 4d and 74 connected via
e, a pilot ball l-74f that opens at the upper end of the spool 75 and is connected to the hydraulic piping 80 via a branch hydraulic piping 82; A pilot port 74g connected to the pipe 81 and an insertion hole 74h through which the actuator 76a of the proportional solenoid 76 is inserted are formed.

The spool 75 also has a supply port 74a.

74b and the land 758 facing the return boat 74c.
75c is formed. A pressing spring 84 is interposed between the lower end surface of the land 75b and the bottom wall of the valve housing 74, and the spool 75 is moved by this pressing spring 84 and a spring that presses an actuator 76a of a proportional solenoid 76, which will be described later. , are held in a neutral position where the lands 75a to 75c close each boat 74a to 74c.

Further, the proportional solenoid 76 presses the spool 75 via an axially slidable actuator 76a, an excitation coil 76b that drives the actuator 76a, and the actuator 76a, and the spool 75 is pushed in balance with the pressing spring 84. It is composed of a pressing spring 85 that holds it in the neutral position.

Next, the overall operation will be explained together with the operation of the directional control valve 66.

Now, when the vehicle is traveling straight at a constant speed on a good road with no large irregularities, the command value ■ commanded from the controller 16 is almost zero, and the direction control valve 66 The proportional solenoid 76 is in a de-energized state. Therefore, the pressure at the pilot boats 74f and 74g of the valve housing 74 is lower than the pressing force of the pressing springs 84 and 85, so the spool 75 is held at the neutral position shown in FIG. Boats 74a to 74c are blocked by boats 75c.

As a result, the pressures in both pressure chambers A and B of the hydraulic cylinder 62FL (62RL) are maintained at the same predetermined value.

As a result, the stroke amounts of the hydraulic cylinders 62FL, 62RL and the connecting rods 64, 64 are reduced, so no torsional force is applied to the anti-roll bars 10F, IOR, and the anti-roll bars 10F.

10R is not involved in roll stiffness. Therefore, the spring constant of the suspension is maintained at a small value, and good riding comfort is also obtained.

Also, assume that the vehicle is traveling straight on a road surface with relatively large and random irregularities. In this case, the left and right wheels are 4 FL.

When 4RL, 4FR, and 4RR move up and down in opposite phases and, for example, an excitation force is input to the front left wheel 4FL by riding over a convex part of the road surface, the stroke amount of the hydraulic cylinder 62FL is reduced, and the pressure in the lower pressure chamber is reduced. Rise. In response, the pressure of the pilot boat 74f exceeds the pressing force of the pressing spring 84, and the spool 75 is displaced from the neutral position to the downward offset position. Therefore, supply boat 74
b and the output port door 4e, and between the output port door 4d and the return boat 740, respectively, so that hydraulic oil from the hydraulic source 20 is supplied to the lower pressure chamber B, and hydraulic oil in the upper pressure chamber A is supplied to the lower pressure chamber B. is discharged to the drain side of the source 20.

As a result, the lower pressure chamber B of the hydraulic cylinder 62FL is in an increased pressure state and the lower pressure chamber A is in a reduced pressure state, so that the fluctuating pressure in the pressure chambers A and B due to the excitation force and the adjusted pressure related to the spool movement are offset. , to reduce vibrations input to the wheels 4FL and transmitted to the vehicle body.

Conversely, for example, when the wheel 4FL engages with a road surface depression and a vibration force is input that causes the hydraulic cylinder 62Fl to displace downward, the pressure in the lower pressure chamber B of the hydraulic cylinder 62FL increases, so that the pressure of the pilot boat 74g increases. The pressure exceeds the pressing force of the pressing spring 85, and the spool 75 is displaced from the neutral position to the upper offset position, and accordingly, the lower pressure chamber B is connected to the drain side of the hydraulic source 20 and the pressure is reduced. At the same time, since the lower pressure chamber A is connected to the hydraulic oil supply side of the hydraulic pressure 'a20 and is increased in pressure, the vibration input that is transmitted to the vehicle body and lowers it is reduced.

On the other hand, when the vibration cannot be absorbed even by this vibration reduction operation, the left and right hydraulic cylinders 62FL, 62RL and the connecting rod 6 due to random irregularities.
The stroke amount of 4.64 also becomes different, and the anti-rubber 10F, IO
R is twisted, and roll rigidity is increased by the torsional rigidity of the bar 10F and IOR itself, and roll can be suppressed.

Furthermore, suppose that the vehicle is turned from the above-mentioned constant-speed straight-ahead state to make a left turn, for example, on a road surface with relatively large and random irregularities. As a result, a lateral acceleration is generated in the right lateral direction according to the vehicle speed and the turning angle, and this acceleration causes an inertial force (centrifugal force) F.
acts to the right as shown in FIG.

However, the command value I at this time is calculated by performing the same calculation as in each of the embodiments described above, and a negative command value I is output to the proportional solenoid 76 of the directional control valve 66. Due to this excitation, the actuator 7
6a presses the spool 75, and the spool 75 moves from the neutral position to the lower offset position, reducing the operating pressure in the lower pressure chamber A of the cylinder 62FL62RL and increasing the operating pressure in the lower pressure chamber B, as described above. let As a result, the anti-roll bar 10F and IOR are returned by 1, and the strokes of the cylinders 62FL and 62RL are forcibly shortened.

This reduction in stroke amount creates a force that resists the force that tends to lift the inner wheels of the vehicle, while the wheel side members 22 and 24 resist the force that tends to sink the outer wheels of the vehicle through the connecting rods 64 and 64. As a result, a roll reaction force similar to that of the second embodiment is generated as a whole. This allows the vehicle body 2 to be held substantially flat and improves ground contact.

The above control operations when turning are completely the same when turning left.

By passing through unevenness during such roll control,
Even if there is vibration input from the road surface at a relatively low frequency (frequency in the sprung mass resonance frequency range), the direction control valve 66 will accurately absorb the vibration input and reduce the hydraulic The stroke amount of the cylinders 62FL and 62RL is maintained at a value based on the differential pressure between the pressure chambers A and B according to the command value I. Therefore, the transmission of vibration to the vehicle body during turning is significantly reduced, resulting in better ride comfort and better ground contact (thereby improving running stability).

Furthermore, in the third embodiment, the number of installed hydraulic cylinders and control valves is reduced by half compared to the second embodiment, which has the advantage of simplifying the configuration and reducing parts costs. .

In addition, in the third embodiment, the hydraulic cylinder 62FL
, 62RL and the connecting rod 64. The mounting positions of the connecting rods 64 and 64 may be reversed.

Furthermore, although each of the above embodiments describes the case where hydraulic oil is used as the working fluid, any fluid with a low compressibility may be used. Furthermore, the effective pressure receiving area of each fluid pressure cylinder may be the same at the front and rear of the vehicle, if necessary.

〔Effect of the invention〕

As explained above, the present invention provides a fluid pressure cylinder interposed between an anti-roll bar and an unsprung member of a vehicle body or suspension, and commands the operating pressure of this fluid pressure cylinder in accordance with lateral acceleration. Since it is controlled by a pressure control valve that converts the value into pressure, the cylinder pressure is adjusted according to the lateral acceleration even when turning on a road surface with relatively large irregularities, and the cylinder pressure is adjusted to resist torsional rigidity. As the roll bar is actively twisted, a roll reaction force is generated and roll is suppressed, and vibrations caused by unevenness input from the road surface are directly fed back to the pressure control valve and absorbed. Unlike conventional devices, the vertical oscillation of the vehicle body during turning is significantly reduced, maintaining good ride comfort, and ensuring ground contact even when turning lateral acceleration is large, improving vehicle running stability. It also has the effect of improving sex.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the invention according to this application, FIG. 2 is a sectional view of the pressure control valve of the first embodiment, and FIG.
The figure is the characteristic diagram of the output pressure of the pressure control valve shown in Figure 2, and the characteristic diagram of the output pressure of the pressure control valve shown in Figure 4.
5 is a block diagram of the controller of the first embodiment, FIG. 5 is an explanatory diagram of the operation of the first embodiment, FIG. 6 is a schematic configuration diagram showing the second embodiment of the invention according to this application, and FIG. 7 is a block diagram of the controller of the first embodiment. 8 is a schematic configuration diagram showing the third embodiment of the invention according to this application, FIG. 9 is a sectional view of the directional control valve of the third embodiment, and FIG. 10 is a diagram showing the third embodiment of the directional control valve. FIG. 3 is an explanatory diagram of the operation of the embodiment. In the figure, 2 is the vehicle body, 4FL to 4RR are wheels, 6 is a vehicle stabilizer, and IOF and IOR are anti-roll bars 12
FL~12RR are hydraulic cylinders, 14F. 14R is a pressure control valve, 16 is a controller, 18 is a lateral acceleration sensor, 22.24 is a wheel side member, 62FL, 62
RL is a hydraulic cylinder, and 66 is a directional control valve. Figure 4, 16 Figure 3 Figure 5 Figure Figure L1 U Figure

Claims (5)

[Claims] (1) Equipped with an anti-roll bar whose both ends are attached to the unsprung members of the suspension and whose middle section is attached to be supported by the vehicle body and which generates a torsional reaction force in response to the difference in the vertical movement of the left and right wheels. A stabilizer for a vehicle includes a fluid pressure cylinder interposed between the anti-roll bar and an unsprung member of the vehicle body or suspension, and the operating pressure of the fluid pressure cylinder is controlled only according to a changeable command value. The vehicle is characterized by being provided with a pressure control valve, lateral acceleration detection means for detecting lateral acceleration generated in the vehicle body, and command value calculation means for calculating a command value according to the lateral acceleration detection value of the lateral acceleration detection means. Stabilizer for vehicles. (2) Claim (1), wherein the fluid pressure cylinder is interposed between the vehicle body and a vehicle body support point of the anti-roll bar.
Stabilizer for the vehicle listed. (3) The vehicle stabilizer according to claim (1), wherein the fluid pressure cylinder is interposed between an unsprung member of the suspension and an unsprung member attachment point of the anti-roll bar. (4) The fluid pressure cylinders are installed at predetermined positions on the front, rear, left and right sides of the vehicle, and the pressure chambers of the two fluid pressure cylinders located at the front and rear left side of the vehicle and the single pressure control valve A structure in which the pressure chambers of two fluid pressure cylinders located at the front and rear of the right side of the vehicle and the output side of a single pressure control valve are interconnected.
The vehicle stabilizer according to 1), (2) or (3). (5) Claim (5) wherein the effective pressure receiving area of the fluid pressure cylinder is different between the cylinders located at the front and rear of the vehicle.
The vehicle stabilizer described in 1), (2), (3) or (4).