KR100320501B1 - Rear Wheel Suspension of Four Wheel Steering System - Google Patents

Abstract

The present invention is a concept of the independent suspension device to implement the rear wheel toe independently of the left and right wheels, the response is fast, and the cost can be reduced, and the minimum turning radius can be realized by the free control of the rear wheel during low-speed turning and parking It is possible to optimize the toe conditions at high speeds and lane changes, and can improve the marginal performance, and can change the ideal state without restraining the roll when turning, improving the maneuverability and stability as well as riding comfort. A wheel steering system relates to a rear wheel suspension of a vehicle. The present invention relates to a rear wheel suspension of a vehicle in which a wheel carrier is connected to a vehicle body by two front and rear lower control arms, and includes a shock absorbing means for damping up and down vibrations input from a road surface. Roll control means connected to the inner end and toe control means connected to the inner end of the rear lower control arm.

Description

Rear wheel suspension in 4-wheel steering system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension of a four-wheel steering system vehicle that enables independent control of left and right roll centers and steering, respectively, in a four-wheel steering system applied vehicle.

For example, in a four-wheel steering system, the rear wheels are generally applied in the same manner as the conventional front wheel steering system so that the left and right wheels can be moved at the same time.

However, in the case of forming a four-wheel system as described above, the rear wheel is connected to the steering rack bar of the rear wheel to maintain a large state of inertia, so that the moment of inertia can quickly be overcome so that the rack can be operated quickly. Since a large amount of hydraulic pressure must be applied, of course, a lot of energy is required, as well as the cost for producing it is likely to increase significantly.

However, even if the inner and outer wheels are controlled at the same time, the actual steering effect is mostly due to the outer ring, and the inner ring is only minimal in terms of contribution.

Moreover, a major contribution to the Double Lane Change or Slalom Test may be disadvantageous because the outer ring is constantly changing left and right.

That is, looking at the drawings as described above, Figures 8a, b is a conventional four-wheel steering system, the rear wheel is moved in the same direction in the rear wheel at the high speed slalom bar, the inner wheel of the rear wheel is tow as shown in Figure 8a In the out state, it should be changed to toe-in as shown in FIG. 8B.

However, in this case, since the steering angle change of the rear wheels must be doubled as compared to the three-wheel steering system of FIG. 9, more energy is required.

As a result, the wits are relatively dull and the magnitude of the response delay is significantly larger, resulting in a deterioration of the stability of the vehicle, and a relatively high hydraulic pressure must be applied to reduce its operation delay.

On the other hand, in the three steering system which steers only one wheel, it is in the state of FIG. 9A and becomes the outer ring momentarily in the state of FIG. 9B, and the other wheel returns to the neutral state relatively slowly in the state of FIG. It can be seen that it is very advantageous in terms of energy if it can maintain the standby state for steering.

However, in the conventional four-wheel steering system, as described above, since the rear wheel is provided with the same steering system, it is absolutely impossible to implement the three-wheel steering system, and thus it is difficult to further develop the rear wheel steering system. The problem is that it is a factor.

Accordingly, the present inventors have studied the rear wheel steering system and the rear wheel suspension in order to solve the above problems, and if the independent control of the left and right wheels can be performed using the control arms constituting the suspension, The present invention has been proposed in recognition of the fact that the inner and outer wheels of the rear wheel can be controlled to perform a combination of the suspension and the rear wheel steering without the steering device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suspension device capable of fast response and reducing costs by independently performing left and right wheel tows in the rear wheel as an independent suspension device.

Another object of the present invention can realize the minimum turning radius by the free control of the rear wheel when turning at low speed and parking by realizing the above object, it is possible to optimize the tow state at high speed and lane change, etc. limit performance To provide a suspension that can improve the.

Still another object of the present invention is to provide a suspension device that can improve the maneuverability and stability as well as the riding comfort by changing to an ideal state without suppressing the roll during turning.

1 is a perspective view of a suspension of a four-wheel steering system vehicle according to an embodiment of the present invention.

2 is an operating state diagram when the roll center descends.

3 is an operating state diagram when the roll center is raised;

Figure 4 shows / shows the change of the roll center according to the operation of the invention.

5 is an operational state diagram for toe out control.

6 is an operational state diagram for toe-in control.

7 is a view showing a change state according to the toe control.

8 and 9 are views for explaining the technology of the four-wheel steering system,

8A and 8B illustrate a four wheel steering system,

9A and 9B illustrate a three wheel steering system.

In order to achieve the above objects, the present invention provides a rear wheel suspension of a vehicle in which a wheel carrier is connected to the vehicle body by two lower control arms at the front and rear, and includes shock absorbing means for damping up and down vibrations input from the road surface. And roll control means connected to the inner end of the front lower control arm and toe control means connected to the inner end of the rear lower control arm.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

As shown in Figs. 1 and 2, in the subframe 2 arranged in the vehicle width direction at the rear side of the engine room, the front and rear two lower control arms 4 and 6 have the vehicle width at a predetermined interval before and after. The wheel carriers 10 rotatably supporting the wheels 8 at the wheel-side ends of the lower control arms 4 and 6, and the front side of the wheel carriers 10 in the longitudinal direction of the vehicle body. The trailing arm 12 is arranged to connect with the vehicle body.

In addition, a strut assembly 18, which is a shock absorbing means for absorbing and damping the up and down vibration input from the wheel 8, is disposed by the coil spring 14 and the shock absorber 16 at the upper portion of the wheel carrier 10.

In the above, the lower control arms 4 and 6 support the wheel 8 to move up and down with a predetermined trajectory according to the vibration inputted according to the road surface condition, and accommodate the lateral force applied to the wheel 8, and trailing. The arm 12 supports together with the lower control arms 4 and 6 when the wheel 8 is lifted to accommodate the front and rear forces applied to the wheel 8.

In the vehicle rear wheel suspension device thus constructed, in the present invention, the vehicle body side end connecting portion 20 of the front lower control arm 4 is connected to a predetermined roll control means without being connected to the subframe 2.

The roll control means is a hydraulic actuator 22 which is a driving means disposed left and right with respect to an intermediate part on the upper side of the subframe 2, and the hinge part is hinged fixed to the subframe 2, the hydraulic actuator It is formed of a bell crank 24 for converting the linear reciprocating motion of the 22 into a rotary motion, and one side end of the bell crank 24 is connected to the vehicle body side end connection portion 20 of the lower control arm 4 to connect the bell. The crank 24 is moved up and down in accordance with the rotational direction.

Specifically, the hydraulic actuator 22 in the above is composed of a reciprocating hydraulic cylinder and disposed on the subframe 2 in a horizontal state to expand and contract according to the supply direction of the hydraulic pressure.

And the bell crank 24 has a hinge portion in the middle portion, and the actuator connection portion 26 is protrudingly formed on one side, the connecting portion is hinged with the hydraulic actuator 22 at the front end in a state in which the connecting portion is vertically established, the lower arm connection portion on the other side The 28 is formed in a horizontal state, and at the tip thereof, the vehicle body side connecting portion 20 of the front lower control arm 4 is connected via a horizontal rubber bush, which has an angle of approximately 90 °.

The length of the actuator connecting portion 26 is formed relatively longer than the length of the lower control arm connecting portion 28, which allows the hydraulic actuator 22 to elevate the front lower control arm 4 even with a small force. For sake.

Although the hydraulic supply means for supplying the hydraulic pressure to the hydraulic actuator 22 is not shown in the drawing, a signal input from various sensing means necessary for controlling a roll, such as a vehicle speed sensor, a steering angle sensor, and a lateral acceleration sensor, is required to be calculated by the controller. By supplying the hydraulic pressure pumped from the hydraulic pump to the hydraulic actuator 22, these related technologies are already known techniques, detailed description thereof will be omitted.

When the expansion and contraction action of the hydraulic actuator 22 is made by the above configuration, the bell crank 24 rotates to raise and lower the vehicle body side connecting portion 20 of the lower control arm 4 to adjust the height of the roll center. Roll control is achieved.

And, the tow control means arranged on the rear side of the roll control means is a hydraulic actuator 30 which is a driving means arranged on the left side and the right side on the upper side of the sub-frame 2, as shown in Figure 1, A hinge part is formed of a bell crank 32 which hinge-fixes the subframe 2 to change the linear reciprocating motion of the hydraulic actuator 30 into a rotational motion, and at one end of the bell crank 32, the rear lower The vehicle body side end connection portion 34 of the control arm 6 is connected and lifted in accordance with the rotation direction of the bell crank 32.

Specifically, the hydraulic actuator 30 in the above is made of a reciprocating hydraulic cylinder to expand and contract according to the supply direction of the hydraulic pressure, the free end thereof is arranged in an inclined downward downward connection with the bell crank 36 do.

And the ball crank 36 has a hinge portion in the middle portion, the actuator connection portion 38 is protrudingly formed on one side thereof is connected to the hydraulic actuator 30 and hinged on the front end thereof, the lower control arm connection portion 40 is formed on the other side thereof The vehicle body side connection portion 34 of the rear lower control arm 6 is connected to the front end via a horizontal rubber bush, which has an internal angle of approximately 90 °.

By the above connection configuration, the bell crank 32 has a hinge portion positioned at the uppermost side, and these free ends are disposed in a state of facing downward, and the length of the actuator connecting portion 38 is greater than the length of the lower control arm connecting portion 40. It is formed relatively long in order to allow the hydraulic actuator 30 to elevate the front lower control arm 6 even with a small force.

Although the hydraulic supply means for supplying the hydraulic pressure to the hydraulic actuator 30 is not shown, it is necessary to calculate a signal input from various sensing means necessary for controlling the roll such as a vehicle speed sensor, a steering angle sensor, a lateral acceleration sensor, and the like. By supplying the hydraulic pressure pumped from the hydraulic pump to the hydraulic actuator 30, these related technologies are already known techniques, detailed description thereof will be omitted.

When the expansion and contraction action of the hydraulic actuator 30 is made by the above configuration, the rear part of the wheel 8 is moved by lifting and lowering the vehicle body side connection portion 34 of the lower control arm 6 while the bell crank 24 rotates. Toe control is achieved by pulling or pushing.

Reference numeral 42 in the drawing refers to a mount for connecting the subframe 2 to the vehicle body.

Looking at the roll control process according to the present invention made as described above, when the condition that the driving condition of the vehicle should lower the roll center from the sensor is input, the hydraulic actuator 22 can be extended to the controller not shown To control the direction of hydraulic pressure.

Then, as shown in FIG. 2, the bell crank 24 is rotated clockwise while the hydraulic actuator 22 is extended, thereby lowering the vehicle body side end of the front lower control arm 4 to lower the roll center.

On the contrary, when a condition that the driving condition of the vehicle is to raise the roll center from the sensors is input, the controller controls the direction of hydraulic pressure so that the hydraulic actuator 22 can be contracted.

Then, by rotating the bell crank 24 counterclockwise while the hydraulic actuator 22 is contracted as shown in FIG. 3, the vehicle body side end of the front lower control arm 4 is raised to increase the roll center.

Looking at the height change of the roll center as described above, as shown in Figure 4, the instantaneous center of the wheel (8) relative to the vehicle body in the state that the roll is not adjusted in the direction orthogonal to this at the upper connection of the strut assembly (18) It becomes the intersection C1 of the virtual line formed with the virtual line, and the virtual line which connects the both connection parts of the front lower control arm 4. As shown in FIG.

As a result, the intersection of the connection line between the instantaneous center C1, the ground portion of the wheel 8 and the center line CL of the vehicle body becomes the roll center RC1, and therefore the height of the roll center becomes H1.

When the inner end of the front lower control arm 4 is lowered in the above state, a virtual line orthogonal to the upper connection part of the strut assembly 18 connects both connecting portions of the lower front control arm 4 to be lowered. The intersection of the imaginary line becomes the instantaneous center C2, and the intersection of the instantaneous center C2, the connecting line between the ground portion of the wheel 8 and the centerline CL of the vehicle body is the roll center RC2. Therefore, the height of the roll center is H2.

Contrary to the above, when raising the inner end of the front lower control arm 4, a virtual line orthogonal to the upper connecting portion of the strut assembly 18, and both connecting portions of the raised front lower control arm 4 are raised. The intersection of the connecting line becomes the instant center (C3), and the intersection of the instantaneous center (C3), the connection line between the ground portion of the wheel (8) and the center line (CL) of the vehicle body is the roll center (RC3). Therefore, the height of the roll center is H3.

As described above, the present invention is to minimize the occurrence of roll on the vehicle body while adjusting the height of the roll center according to the conditions of the road or the state of the vehicle body.

In the tow control process, when the condition that the driving condition of the vehicle is to be controlled by the toe-in state from the sensors is input, the controller not shown may control the direction of the hydraulic pressure so that the hydraulic actuator 30 can be extended. do.

Then, as shown in FIG. 5, as the hydraulic actuator 30 is extended, the bell crank 32 is rotated counterclockwise to push the rear lower control arm 6 outward.

In this way, when the rear lower control arm 6 is pushed outward, the rear part of the wheel 8 is pushed outward, thereby changing to a toe-in state.

On the contrary, when the condition that the driving condition of the vehicle should be controlled to the toe-out state from the sensors is input, the controller controls the direction of the hydraulic pressure so that the hydraulic actuator 30 can be contracted.

Then, as shown in FIG. 6, as the hydraulic actuator 30 is contracted, the bell crank 32 is rotated clockwise to pull the rear lower control arm 6.

In this way, when the rear lower control arm 6 is pulled inward, the rear part of the wheel 8 is pulled inward and the change is made to the toe-out state.

Looking at the tow change as described above, as shown in Figure 7, in the state that is not adjusted tow to maintain the same state as the solid line, in this state, as shown in Figure 5 when the hydraulic actuator 30 is extended rear lower control arm 6 is pushed outward like a dashed-dotted line, and the wheel 8 is in a toe-in state.

As shown in FIG. 6, when the hydraulic actuator 30 is contracted, the rear lower control arm 6 is pulled inward like a double-dashed line so that the wheel 8 is in a tow-out state.

As such, the tow control of the wheel 8 may have the meaning of steering intended in the present invention, in addition to being able to obtain the ideal geometry of the suspension by purely controlling the tow according to the general driving conditions of the vehicle.

That is, by controlling the wheel 8 to toe in or toe out according to the turning direction of the vehicle, steering of the rear wheels is achieved.

In addition, according to the suspension device described above, the bell crank connected to the hydraulic actuators 22 and 30 is connected to the hydraulic actuators 22 and 30 directly instead of directly changing the attitude of the wheel 8 by being directly connected to the wheels 8. The connection is made while the angle of (24, 32) is maintained at an angle of about 90 °. By substituting in, the energy consumption rate is at a minimum.

In the above formula, F denotes the force of the hydraulic actuator, S denotes the operating stroke of the hydraulic actuator, and θ denotes the cabinet between the hydraulic actuator and the bell crank.

As described above, the rear wheel suspension device of the four-wheel steering system vehicle according to the embodiment of the present invention is a concept of an independent suspension device, and the tow of the rear wheel is independently performed to the left and right wheels, so that the responsiveness is fast and the cost can be reduced. As the steering is made by the tow control as described above, the minimum turning radius can be realized by the free control of the rear wheels during low speed turning and parking, and the tow state can be optimized at high speeds and lane changes, etc. Marginal performance can be improved.

In addition, since the height adjustment of the roll center can be performed independently of the left and right wheels, there is an effect of improving the maneuverability and stability as well as the riding comfort by changing to an ideal state without suppressing the roll during turning.

Claims (11)

In the rear wheel suspension of a vehicle, the wheel carrier is connected to the vehicle body by two lower control arms at the front and the rear, and includes a shock absorbing means for damping up and down vibrations input from the road surface. Roll control means connected to an inner end of the front lower control arm, And a tow control means connected to the inner end of the rear lower control arm. 2. The apparatus of claim 1, wherein the roll control means comprises: drive means arranged horizontally above the sub-frame to perform stretching operation by a hydraulic power source; And a rotating means for receiving a linear reciprocating motion of the driving means and converting the rotational motion into a rotational motion to raise and lower the front lower control arm. 3. The rear wheel suspension of a four-wheel steering system vehicle according to claim 2, wherein the drive means comprises a reciprocating hydraulic actuator. According to claim 2, The rotating means has a hinge portion in the middle portion, the actuator connection portion protrudes to one side and the lower control arm connection portion is formed on the other side, the actuator connection portion and the lower control arm connection portion has an angle of about 90 ° Rear wheel suspension of a four-wheel steering system vehicle, characterized in that the bell crank. 5. The rear wheel suspension of claim 4, wherein the bell crank is formed to have a length of an actuator connection longer than that of a lower control arm. 5. The rear wheel of a four-wheel steering system vehicle according to claim 4, wherein the bell crank is arranged such that the actuator connection part is vertically connected to the hydraulic actuator, and the lower control arm connection part is arranged to be connected to the lower control arm in a horizontal state. Suspension. The tow control means according to claim 1, further comprising: driving means arranged at an inclined downward direction with the tip portion facing outwardly in an intermediate portion on the sub-frame and configured to expand and contract by a hydraulic power source; And a rotating means for receiving the linear reciprocating motion of the driving means, converting the rotational motion into a rotational motion, and rotating the rear lower control arm up and down. 8. The rear wheel suspension of a four-wheel steering system vehicle according to claim 7, wherein the drive means comprises a reciprocating hydraulic actuator. According to claim 7, The rotating means has a hinge portion in the middle portion, the actuator connection portion protrudes to one side and the lower control arm connection portion is formed on the other side, the actuator connection portion and the lower control arm connection portion has a 90 degree angle Rear wheel suspension of a four-wheel steering system vehicle, characterized in that consisting of a bell crank having. The rear wheel suspension of a four-wheel steering system vehicle according to claim 9, wherein the bell crank has a length of the actuator connection portion longer than that of the lower control arm. 10. The vehicle according to claim 9, wherein the bell crank is arranged such that the intermediate hinge part is positioned at the uppermost side, the connection part of the actuator is connected to the hydraulic actuator, and the lower control arm connection part is connected to the lower control arm. Rear wheel suspension.