JPH07449B2 - Attitude control device for vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle attitude control device in which unsprung members of left and right wheels are connected by a stabilizer.

[Prior Art] By combining the unsprung members of each of the left and right wheels with a stabilizer also called an anti-roll bar, independent movements of the left and right wheels are coordinated to tilt or shake the vehicle when turning. Is known to reduce.

In the stabilizer device, when the left and right wheels are at the same suspension position, the stabilizer does not twist, but when one of the left and right wheels overhangs a protrusion or turns, if the suspension positions of the left and right wheels are significantly different, the torsion of the stabilizer The bar is twisted, and as a reaction thereof, an elastic force acts in a direction of canceling the twist to act to make the suspension positions of the left and right wheels equal.

The posture stability performance of a vehicle is evaluated over several items, but during running, road followability and roll suppression effect when turning are important. When the road surface following property is prioritized, the stabilizer is desired to have a small twist characteristic, whereas when the roll restraining effect is prioritized, the torsional elasticity is preferably large.

However, in the above-mentioned conventional device, since the characteristics of the torsion bar of the stabilizer are fixed, it is inevitable that the torsion bar is set to an appropriate set value for the torsional elastic characteristics, and it is difficult to satisfy both characteristics.

As a means for solving this, it has been proposed to provide a connecting member for varying the connecting distance between the stabilizer and the unsprung member that holds the wheel to variably adjust the torsion characteristic of the torsion bar.

[Problems to be Solved by the Invention] In a vehicle having front and rear wheels equipped with stabilizers, the torsional rigidity of the front wheel stabilizer and the torsional rigidity of the rear wheel stabilizer are improved from the viewpoint of improving running stability of the vehicle. Originally, it is desirable to set a different value, and since the load on the front wheel side stabilizer is larger than that on the rear wheel side stabilizer, generally set the torsional rigidity of the front wheel side stabilizer to be high. ing.

However, in this case, when the same hydraulic cylinder that varies the torsional rigidity of the stabilizer is used and the same pressure oil is supplied from a single hydraulic source, the amount of change in the torsional rigidity is the same. However, since the original set values of the torsional rigidity are different, the torsional rigidity cannot be varied in the same ratio between the front and rear wheels. Therefore, when the roll of the vehicle is suppressed, the initial set ratio of the front wheel side and the rear wheel cannot be maintained, the sufficient effect of suppressing the roll cannot be obtained, and the occupant feels uncomfortable. Problems arise.

Therefore, the present invention solves the above-mentioned problems, and when the stabilizers having originally different torsional rigidity are mounted on the front wheel side and the rear wheel side, how to balance both stabilizers while adopting a simple configuration. An object is to provide a vehicle attitude control device that can be driven well.

[Means for Solving the Problem] In a vehicle attitude control device of the present invention made to achieve the above object, a stabilizer capable of changing torsional rigidity according to expansion and contraction of a hydraulic cylinder is provided on a front wheel side and a rear wheel side. In each of the vehicle attitude control devices, a single hydraulic pressure source that supplies pressure fluid to the hydraulic cylinders of the front wheel side and rear wheel side stabilizers, and the front wheel side and the rear wheel side from the single hydraulic pressure source are provided. And a pressure oil supply means for supplying and controlling a similar pressure oil to the hydraulic cylinder of the stabilizer on the wheel side, the stabilizer on the front wheel side and the stabilizer on the rear wheel side are set to different values in their torsional rigidity, The cylinder diameter of the hydraulic cylinder having the smaller torsional rigidity between the front wheel side stabilizer and the rear wheel side stabilizer is the cylinder diameter of the hydraulic cylinder having the larger torsional rigidity. Characterized by being smaller than.

[Operation] In the vehicle attitude control device of the present invention having the above-described configuration, during turning, the pressure oil supply unit supplies the same pressure oil from the single hydraulic power source to the hydraulic cylinders of the front wheel side and rear wheel side stabilizers. Supply control. Here, in the front wheel side stabilizer and the rear wheel side stabilizer, the cylinder diameter of the hydraulic cylinder having the smaller torsional rigidity is set smaller than the cylinder diameter of the hydraulic cylinder having the larger torsional rigidity. Therefore, even if the same pressure oil is supplied from the same hydraulic power source, the torsional rigidity can be changed at substantially the same ratio. Therefore, it is possible to obtain a stable roll suppressing effect at the time of turning and to prevent the occupant of the vehicle from feeling uncomfortable. [Embodiment] FIG. 1 is an overall view of a vehicle attitude control device to which the present invention is applied. The configuration is shown. The front wheels of a four-wheel vehicle indicated by reference numerals 10 and 12 represent steered wheels, and the wheels 10 and 12 are unsprung members 14 and 16, respectively.
The unsprung members are supported by the vehicle body via shock absorbers 26 and 28, respectively. Stabilizer 1
A front wheel side torsion bar 30 having torsional elasticity is rotatably supported by rubber bearings 32 and 34.

One end 36 of the stabilizer 18 is connected to the unsprung member 14 via a connecting member 22 capable of adjusting a connecting distance.
The connecting length between the end of 18 and the unsprung member 14 is
It is adjustable by expansion and contraction. The other end 38 of the stabilizer 18 is fixedly connected to the other unsprung member 16 by a suitable connecting method. The unsprung members 14 and 16 that are connected to one end or the other end of the stabilizer 18 may be connected to the lower arms, or may be the shock absorbers 26 and 28 and the wheel side fixing portions as shown in FIG. .
In FIG. 2, the other end 38 of the stabilizer 18 is connected to the shock absorber 28 using a tie rod 40.

A wheel manipulating mechanism 44, which is connected to a steering wheel 42, is connected to the respective unsprung members 14 and 16 for steering the vehicle.

Each of the rear wheels indicated by reference numerals 46 and 48 is an unsprung member 51 and 52, respectively.
And is coupled to the vehicle body via a suspension device (not shown). The rear wheel stabilizer 50 has one end connected to the unsprung member 51 via the connecting member 56 and the other end fixedly connected to the unsprung member 52, as in the case of the front wheel. In the rear wheel side stabilizer 50, the diameter of the torsion bar 50a is smaller than that of the front wheel side so that the torsional rigidity becomes smaller than that of the front wheel side.

As shown in FIG. 3, the connecting member 22 is mainly composed of a piston 58 and a cylinder body 60. A piston rod 62, which is constructed and fixed integrally with the piston 58, is connected to the shock absorber 26 at a mounting portion 64. The cylinder body 60 has the above-mentioned stabilizer at the mounting portion 66.
Combined with 18.

The piston 58 is slidably movable in the cylinder body 60 in the vertical direction in the figure via a sealing O-ring 68, and the piston rod 62 is also supported by the piston body 60 via the O-rings 70 and 72. Has been done.

The inside of the cylinder body 60 is divided into a lower cylinder chamber 74 and an upper cylinder chamber 76 by the piston 58, and each of the cylinder chambers 74 and 76 is provided with an operating means (not shown) via ports 78 and 80, respectively. It is in communication with a fluid supply device (a hydraulic circuit indicated by reference numeral 24 in FIG. 1).

In the structure of the connecting member 22, when the fluid pressure is applied to the lower cylinder chamber 74, the volume of the lower cylinder chamber 74 is increased, and when the fluid is pushed out from the upper cylinder chamber 76, the piston 58 is moved to the cylinder. It can be pushed upward relative to the body 60. At this time, the mounting portion 64 of the piston rod 62 and the mounting portion of the cylinder body 60
The relative distance to 66, that is, the stabilizer in FIG.
The connection distance between one end 36 of 18 and the unsprung member 14 is extended.

On the other hand, when the volume of the upper cylinder chamber 76 is increased by applying fluid pressure to the upper cylinder chamber 76, the piston
It is possible to move 58 downward relative to the cylinder body 60. As a result, contrary to the above, the connection distance between the one end 18 of the stabilizer 18 and the unsprung member 14 is shortened.

Therefore, the adjustment of the connection distance by the connection member 22 can be adjusted by adjusting the amount of fluid supplied to both cylinder chambers.

On the other hand, the rear wheel side connecting member 56 has substantially the same configuration as the front wheel side connecting member 22, but as described above, the rear wheel side torsion bar 50 is thinner than the front wheel side and has a low torsional rigidity. Therefore, the diameter of the hydraulic cylinder (not shown) is correspondingly reduced.

A hydraulic circuit 24 as a fluid supply device, which constitutes the operating means of the present invention.
Is a hydraulic pump 82, 4-port solenoid directional control valve 84 and hydraulic line
It is composed of 86-92. The hydraulic pump 82 is driven by an electric motor that is energized and deenergized by the electric drive signal O ₁ , but if necessary, it can be an engine-driven type and can be shared with the power steering device.

In the connecting members 22 and 56, the lower pipeline 90 that communicates with each lower cylinder chamber (74 in FIG. 3) and the upper pipeline 92 that communicates with each upper cylinder chamber (76 in FIG. 3) are 4
It is connected in front of the port electromagnetic switching valve 84 so that the fluid can be simultaneously supplied to the upper or lower cylinder chamber.

The 4-port solenoid switching valve 84 is selectively switched to the 3 position by the electric drive signal O ₂ , and in the first position (neutral mode), the pump discharge side pipe line 86 and the return pipe line 88 are connected and connected. Members 22, 56 lower line 90 and upper line 9
Contact 2 At this time, since the upper and lower cylinder chambers of each connecting member are sealed by the pipe lines 90, 92 and the valve 84,
The connection distance is held unchanged.

Next, in the second position (extension mode), the pump discharge side pipe line 86
And the lower line 90, and the return line 88 and the upper line 92. Therefore, the volume of the lower cylinder chamber of each connecting member is increased, and the connecting distance is extended.

Next, in the third position (reduction mode), the pump discharge side pipe line 86
And the upper line 92 and the return line 88 and the lower line 90. Therefore, the volume of the upper cylinder chamber of each connecting member is increased, and the connecting distance between the connecting members is reduced.

The posture control of the vehicle according to the present invention can be realized by adjusting the connection length of the connecting members 22 and 56 by adjusting the hydraulic pressure by the hydraulic circuit 24 in the configuration described above. This is performed by controlling the 24 hydraulic pumps 82 and the electromagnetic switching valve 84 by the electric drive signals O ₁ and O ₂ .

Next, the operation of the above configuration will be described.

Now, when it is determined that the torsional rigidity of the stabilizer should be adjusted by changing the connecting distance of the connecting members 22 and 56 in the arithmetic processing unit 94 based on the detection signals of the speed sensor 96 and the steering sensor 98, the hydraulic pump A control signal is sent to 82 and the electromagnetic switching valve 84. As a result, the pressure oil of the hydraulic pump 82 is supplied to the hydraulic cylinders of the front and rear wheel connecting means 22, 56 via the electromagnetic switching valve 84. At this time, since the diameter of the hydraulic cylinder on the front wheel side is larger than that on the rear wheel side, the biasing force to the torsion bar generated by the hydraulic cylinder on the front wheel side is larger than that on the rear wheel side, but the rigidity of torsion bar 30 on the front wheel side is Since it is set higher, the two are offset, and the torsional rigidity generated in the stabilizers of the front and rear wheels becomes substantially equal.

Therefore, even if the torsion bars of the front and rear wheels have different inherent rigidity, the stabilizers of the front and rear wheels have the same torsional characteristics with the hydraulic pressure supplied from a single hydraulic pressure source, so that the vehicle has a stable posture during turning.

Moreover, since separate hydraulic pressure sources are not used for the front and rear wheels, that is, pressure oil is supplied to the front and rear wheels by a single hydraulic source, the configuration is simple.

[Effect of the Invention] As described above, according to the present invention, the torsional rigidity of the stabilizers for the front and rear wheels is set to different values, and the diameter of the hydraulic cylinder having the smaller torsional rigidity has the larger torsional rigidity. Since it is set smaller than the cylinder diameter, even if the same pressure oil is supplied from the same hydraulic pressure source, the torsional rigidity can be changed at substantially the same ratio. Therefore, a stable roll suppressing effect can be obtained during turning, and it is possible to prevent an occupant of the vehicle from feeling uncomfortable. Moreover, since the front and rear wheels can be controlled by a single hydraulic power source, the configuration is simple.

[Brief description of drawings]

1 is an overall configuration diagram of an embodiment of the present invention seen from above the vehicle, FIG. 2 is a diagram of the front wheel side suspension device portion in FIG. 1 seen from the front of the vehicle, and FIG. 3 is a connecting member. FIG. 10,12 …… Wheels 14,16,51,52 …… Unsprung members 18,50 …… Stabilizer 22,56 …… Coupling means 24 …… Hydraulic circuit as actuating means 26,28 …… Shock absorber 82 …… Hydraulic pump 84 …… Solenoid switching valve 86 to 92 …… Pipe line 94 …… Computing unit 96 …… Speed sensor 98 …… Steering sensor 100 …… Stroke sensor

Claims (1)

[Claims] 1. A vehicle attitude control device comprising a front wheel side stabilizer and a rear wheel side stabilizer capable of changing torsional rigidity according to expansion and contraction of a hydraulic cylinder, wherein the front and rear wheel side stabilizer hydraulic cylinders are provided. On the other hand, it is provided with a single hydraulic pressure source for supplying a hydraulic fluid, and a pressure oil supply means for controlling the supply of similar pressure oil from the single hydraulic pressure source to the hydraulic cylinders of the stabilizers on the front and rear wheels. The front wheel side stabilizer and the rear wheel side stabilizer are set to have different torsional rigidity, and the front wheel side stabilizer and the rear wheel side stabilizer have the smaller torsional rigidity. An attitude control device for a vehicle, wherein a cylinder diameter of a cylinder is set to be smaller than a cylinder diameter of the hydraulic cylinder having a larger torsional rigidity.