KR100221576B1 - Suspension bush controlling device for a vehicle - Google Patents

Abstract

The object of the present invention is to install a hydraulic bushing at the body side connection portion of the bush lower arm for McPherson suspension, and to secure the vibration bushing function, which is the original function of the bushing, while maintaining the hydraulic bushing in the vertical direction of the vehicle body according to the driving situation. It is related with the bushing control device for the suspension of the vehicle to move as much as possible and to ensure the stability of the straight and high-speed driving and the vehicle stability when turning.

In the present invention, in installing the hydraulic bushing on the lower arm and the mounting portion of the vehicle body, the directional control valve is controlled according to the road input vibration size and frequency, and the pressure of both fluid chambers in the hydraulic bushing is controlled. Suspension of the vehicle, characterized by adjusting the elastic modulus, controlling the pressure of the hydraulic bushing and the fluid chamber according to the driving conditions to control the roll center position of the vehicle, and to ensure turning stability and straight running stability even in the event of a system failure Bush control.

Description

Bush control device for vehicle suspension

1 is a configuration diagram of a conventional bushing control device for suspension.

2 is a cross-sectional view of a conventional hydraulic bush.

3 is a system diagram in a state where the hydraulic bush of the embodiment of the present invention is installed.

4 is a plan view of FIG.

5 is a cross-sectional view of the hydraulic bush.

6 is a block diagram of a hydraulic bush control device according to the present invention.

7 and 8 are views showing the operating state of the hydraulic bush.

9 is a conceptual diagram showing the change of the roll center by the bush control of the lower arm.

＊ Explanation of symbols for main parts of drawing

1: wheel 2: knuckle

4: lower arm 5: bush crossmember for suspension

6: oil tank 7: electronic control device

40: Hydraulic Bushing 41: Conventional Bushing

61: strainer 62: hydraulic pump

63: pump drive device 64: relief valve

65: 4-port 3-position directional control valve 66: 2-port 2-position directional control valve

67: attenuator 71: vehicle speed sensor

72: steering angle sensor 661: return spring

650, 660: on / off solenoid

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device for an automobile, and more particularly, to sufficiently secure a vibration isolation function, which is an original function of a hydraulic bushing, mounted on a vehicle side connection portion of a McPherson suspension bush lower arm according to driving conditions. An object of the present invention is to provide a suspension control device for a vehicle in which a hydraulic bush is moved by a predetermined distance in the up and down direction of a vehicle body, thereby ensuring stability of straight and high-speed driving and vehicle stability when turning.

The McPherson suspension control device forms two fluid chambers in the bushings mounted on the body connection part of the lower arm, and changes the position of the body connection part of the lower arm up and down by hydraulic pressure to change the position of the roll center of the vehicle when turning or driving at high speed. The configuration is variable in the up and down directions.

Referring to the conventional vehicle suspension apparatus in more detail, as shown in FIG. 1, a control unit comprising a lateral acceleration sensor 520, a vehicle speed sensor 521, and a control device 52, a hydraulic pressure source 6, and four ports It consists of a hydraulic-position part comprised from the three-position direction control valve 51 and the hydraulic bushing 50. As shown in FIG.

The hydraulic bush 50 presses the elastic body 503 between the inner cylinder 500 and the outer cylinder 501 made of metal as shown in FIG. 2, and two fluid chambers 504 and 505 are installed inside the elastic body. The outer cylinder is connected to the lower arm and the inner cylinder is connected to the vehicle body, respectively.

In addition, two fluid chambers are formed in the body connecting portion bush 50 of the lower arm 4, and the position of the body connecting portion of the lower arm is vertically changed by hydraulic pressure to change the position of the roll center of the vehicle up and down in the case of an advance or high speed driving. Suspension bushing controls were made available.

When the driving state of the vehicle is input from the sensor and the control device operates the direction control valve, pressure is applied to one of the fluid chambers in the hydraulic bush, and atmospheric pressure is applied to the opposite fluid chamber, and a pressure difference occurs between the two fluid chambers. .

The fluid chamber to which pressure is applied expands and the fluid chamber that is not pressurized contracts so that the outer cylinder of the hydraulic bush (body connection part of the lower arm) generates a relative position change with respect to the inner cylinder of the hydraulic bush (body). The position of the body connection portion of the arm changes in the up and down directions.

In this way, when the mounting position of the lower arm is changed on the vehicle body side, the position of the roll center of the vehicle is changed in the up and down directions due to the change in the kinematic characteristics of the suspension bushing device. (Roll) generation can be suppressed.

However, the above-mentioned conventional method is required to apply a constant pressure in the hydraulic bush during normal vehicle driving, but is equal to both fluid chambers 504 and 505 in the hydraulic bush 50 due to the characteristics of the directional control valve 51. There is a disadvantage in that the pressure cannot be maintained.

In addition, even if an equal pressure is applied to both fluid chambers 504 and 505 in the hydraulic bush 50, from the viewpoint of vibration insulation to block the transmission of the vibration of the wheel, which is an original function of the suspension bush, to the vehicle body, As shown in FIG. 1, when the direction control valve 51 is in the neutral position, both fluid chambers 504 and 505 in the hydraulic bushing 50 are isolated from the outside to form a closed flow path, thereby making the fluid incompressible. Due to the state that the fluid is enclosed in the rubber bush, there is a problem such that the characteristics of the hydraulic bush can not be set properly during vibration isolation.

If a system failure occurs while driving, there is a problem that due to the above problems can not perform the original function of the hydraulic bush, causing serious problems in the ride comfort and running stability.

The present invention has been made to solve the above-mentioned conventional problems, and the hydraulic bushing is attached to the vehicle body side connection portion of the bush lower arm for suspension, and the frequency input from the road surface as well as the vibration insulation function which is the original function of the bush. Accordingly, the purpose of the present invention is to provide a bushing control device for the suspension of the vehicle to improve the steering stability and ride comfort by adjusting the elastic modulus of the bush.

In addition, the present invention is to control the roll center height of the vehicle by moving the hydraulic bushing in a vertical distance in the vertical direction of the vehicle according to the driving situation to ensure a straight running stability, high-speed driving stability and vehicle stability at the time of turning It is to provide a bushing bush control device for the suspension of the vehicle.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and examples.

3 to 9 show reference drawings for explaining a suspension control device for a vehicle according to the present invention.

As shown in Figs. 3 and 4, the hydraulic bush 40 is applied to the bush near the center of the wheel of the lower body 4 of the lower arm 4 of the suspension bush.

The hydraulic bush 40 is an elastic body 402 provided between the bush outer cylinder 401, the bush inner cylinder 403, the bush side plate 407, and the bush outer cylinder 401 and the inner cylinder 403 as shown in FIG. ) And a fluid chamber 404 and 405 symmetrically installed in the elastic body 402, a stopper 408 to prevent abnormal deformation of the hydraulic bush 40, and to supply and exhaust hydraulic oil to the fluid chamber 404 and 405 from the outside. To this end, a hydraulic fitting 406 is attached to the outer cylinder.

In addition, the hydraulic system for supplying hydraulic pressure to each of the fluid chambers 404 and 405 of the hydraulic bush 40 includes an oil tank 6, a hydraulic pump 62, and the hydraulic pump 62 as shown in FIG. Two-port, two-position directional control valves 67 and 68 that determine whether to supply or exhaust pressure to each of the fluid chambers 404 and 405 of the electric motor 63 and the hydraulic bush 40 as a power source for driving. A two-port two-position directional control valve 66 that determines the communication between the two fluid chambers when driving the vehicle, and shorts the flow paths of the two fluid chambers 404 and 405 when the bush is controlled. It consists of the relief valve 64 which sets the reactor 67 and system pressure.

In addition, the control device for controlling the hydraulic bushing after detecting the driving state of the vehicle from the vehicle speed sensor 71, the steering angle sensor 72, the electric command signal to the direction control valves (65, 66), the electric motor (63) It consists of the electronic control apparatus 7 which sends out.

The hydraulic parts are integrated into the hydraulic modulator 60 in consideration of assembling, mounting, and the like to minimize the mounting space.

Notably, 1 is a wheel, 2 is a knuckle, 31 is a coil spring, 41 is a convention bush, and 5 is a suspension cross member.

According to the embodiment of the present invention configured as described above, the hydraulic bushing is mounted on the vehicle body side connection portion of the suspension lower arm to ensure sufficient vibration isolation function, which is the original function of the bush during driving of a vehicle, while driving according to driving conditions during high-speed driving and turning. The hydraulic bush is moved by a certain distance in the vertical direction of the vehicle body to ensure the stability of driving straight and high-speed driving and vehicle stability at the time of turning. First, the operation state of the hydraulic bush 40 during normal driving of the vehicle is removed. It demonstrates with reference to FIG.

In the normal driving of the vehicle, the electric control signals I _FL , I _UP , I _DN , and I _MR = 0 are not transmitted from the electronic control device 7 to the direction control valves 65 and 66 and the electric motor 63. The directional control valve 65 is in a neutral state to block the flow path from the hydraulic source, and at the same time, the directional control valve 66 is provided with two fluid chambers 404 and 405 in the hydraulic bush 40 by the return spring 661. Are connected to each other via an orifice 663.

In addition, when the vehicle is driving on a rough road, road input vibration of a low frequency large amplitude region is generated at the wheel and transmitted to the vehicle body through the lower arm, at which time between the fluid chambers 404 and 405 communicated with the hydraulic bush. When the electrical control signal is applied from the electronic control device 7 to the orifice 663 in order to set the flow path cross-sectional area of the mounted orifice 663 to the maximum, the elasticity characteristic of the hydraulic bush becomes soft, and the low frequency is caused by the damping characteristics of the fluid. The transmission of the large amplitude vibration from the lower arm to the vehicle body can be significantly reduced.

Referring to FIG. 7, the operation state of the hydraulic bush 40 for improving the straight running stability during high speed straight driving of a vehicle is as follows.

When the vehicle travels on a good road, such as a pavement, road input vibrations (small displacements) of relatively high frequency micro amplitudes are generated from the wheels and transmitted to the vehicle body through the lower arm. The electric control signal is applied from the electronic controller 7 to the direction control valve so as to set the flow path cross-sectional area to the minimum by switching the direction control valve mounted between both fluid chambers. While reducing vibration from the lower arm to the vehicle body, noise generated by high frequency vibration can be minimized.

On the other hand, when the high frequency large amplitude input is accidentally inputted, the pressure change generated in the fluid chamber in the hydraulic bush absorbs the pressure change by the movement of the piston 671 of the attenuator 67 to obtain an effective vibration insulation effect. do.

As shown in FIG. 7, the vehicle moves the position of the lower body side connection portion of the lower arm in order to improve driving stability in a straight road on a high-speed straight road such as a pavement.

In general, lowering the position of the roll center during high-speed straight driving is advantageous in terms of riding comfort as the second straight disturbance due to the straight running stability of the vehicle and the disturbance from the road surface is reduced.

Accordingly, in the present invention, as shown in FIG. 7, the high speed straight driving state of the vehicle is detected from the vehicle speed sensor 71 and the steering angle sensor 72, and the electronic controller 7 transmits an electric signal I _MR to the electric motor 63. The hydraulic motor is generated by driving the electric motor and the hydraulic pump 62.

Electrical operation signals are applied to the direction control valves 65 and 67 to operate the valves. At this time, as shown in the figure, the pressure in the lower fluid chamber 405 in the hydraulic bush is increased and the pressure in the upper fluid chamber 404 is lowered.

At this time, since the inner cylinder 403 of the hydraulic bush is fixed to the vehicle body side with a bolt, the outer cylinder 401 of the hydraulic bush has a relative movement in the lower direction of the vehicle with respect to the inner cylinder 403, and as a result, a lower arm connected to the outer cylinder ( The position of the roll center determined by the geometric shape of the lower arm 4 and the strut 3 as shown in FIG. 9 is lowered by the vehicle body side mounting position of 4) by "h ₁ ". It can be lowered from the "H" position to the "H ₂ " position.

As a result, secondary driving disturbance due to the straight running stability of the vehicle and the disturbance from the road surface is reduced, thereby improving the riding comfort.

When turning the vehicle, the operation of moving the position of the lower body side connection portion of the lower arm upward to improve turning stability is as shown in FIG.

In general, when the vehicle is turning and driving at a high speed straight line, increasing the position of the roll center increases roll stiffness, which enables roll suppression, thereby improving turning stability of the vehicle.

Thus, in the present invention, it is possible to calculate the lateral acceleration when the vehicle turns from the vehicle speed sensor 71 and the steering angle sensor 72. Accordingly, the electronic control device 7 detects whether the vehicle is turned and the electric motor 63 The operation signal I _MR is transmitted to operate the electric motor and the hydraulic pump 62 to generate oil pressure.

In addition, the direction control valves (65, 67) by giving an electric operation signal (I _FL , I _UP ) to operate. At this time, the pressure of the upper fluid chamber 404 in the hydraulic bush is increased, and the pressure of the lower fluid chamber 405 is lowered, and as a result, the vehicle body side mounting position of the lower arm is raised upward by "h ₂ ". The position of the roll center, which is determined by the geometric shape of the arm 4 and the thrust 3, is increased from "H" to "H ₁ ", so that the roll rigidity is increased and roll suppression is possible. Will be.

In the event of a system failure, the operating state of the inlet bush 40 to ensure vibration isolation and stability will be described based on FIG.

If a system failure occurs while driving, the electric control signals I _FL , I _UP , I _DN , and I _MR = 0 are transmitted from the electronic control unit 7 to the direction control valves 66 and 65 and the electric motor 63. Since it is not transmitted, the directional control valve 65 is switched to block the flow path from the hydraulic source, and the directional control valve 66 is connected to the two fluid chambers 404 and 405 in the hydraulic bush 40 by the return spring 661. The orifices 663 communicate with each other, and the hydraulic motor is not operated.

Therefore, both fluid chambers 404 and 405 communicate with each other by the orifice 663 mounted between the two fluid chambers of the hydraulic bush. The elastic characteristics of the hydraulic bush become soft, and the vibrations of the hydraulic bushes cause vibrations. It is possible to reduce the transmission from the lower arm to the vehicle body to ensure the stability.

The present invention as described above is a conventional hydraulic pressure supply device for the hydraulic bush consisting only of the four-port three-position directional control valve, the two-port two-position directional control valve 66 and the four-port three-position directional control valve 65 and the attenuator 67 By employing the (), it is possible to set and maintain a constant oil pressure in the upper and lower fluid chambers 404 and 405 of the hydraulic bush 40 during normal driving, thereby improving ride comfort and vibrating insulation.

In addition, when no electric control signal is applied to the directional control valves 65 and 66, the upper and lower fluid chambers 404 and 405 of the hydraulic bush 40 are connected by an orifice 663 flow path, thereby closing the hydraulic circuit itself. Hydraulic circuit) and the orifice 663 can be connected to this flow path to adjust the flow cross-sectional area of the variable orifice in two stages, and during normal driving, hydro-dynamic damping of the hydraulic bush 40 is performed. Through this function, it is possible to prevent the vibration of the lower arm from being transmitted to the vehicle body at low frequency and high displacement inputs, and to significantly reduce noise generation at high frequency and low displacement inputs.

In addition, by controlling the pressure of the fluid chamber of the hydraulic bush using the hydraulic source and the directional control valve, the position of the vehicle body mounting portion on the lower arm is changed up and down to change the position of the roll center. It is possible to provide a suspension bush control device which can secure the linear stability of the vehicle and can reliably perform the vibration isolation function, which is the original function of the hydraulic bush, even when a system failure occurs while driving. It is characterized by such points.

Claims (7)

An oil pressure bush is installed at the lower arm and the mounting portion of the vehicle body, and an oil pressure source for supplying oil pressure to the oil pressure bush, a control valve for controlling the oil pressure supplied, and an electric control signal according to the driving situation of the vehicle are provided. A four-port three-position directional control valve (65) for determining whether to supply or exhaust pressure to each fluid chamber (404, 405) of the hydraulic bush (40), provided that an electronic control device is applied to the valve. Two-port two-position direction control valve 66, which determines the communication of the two fluid chambers and shorts the flow paths of the two fluid chambers 404 and 405 when the position of the bush is controlled, is connected to both sides from the direction control valve 66 to the pressure. A suspension control device for a vehicle, comprising a pair of attenuators 67 for compensating and damping functions, and relief valves 64 for setting system pressure. The elastic body 402 of claim 1, wherein the hydraulic bush (40) is provided between the bush outer cylinder (401), the bush inner cylinder (403), the bush side plate (407), and the bush outer cylinder (401) and the inner cylinder (403). In the elastic body 402 is installed symmetrically to each other, the fluid chamber (404, 405) having a fitting 406, the stopper 408 to prevent abnormal deformation of the hydraulic bush 40, characterized in that the vehicle Bush control for suspension. 3. The suspension control device for a vehicle according to claim 2, wherein the stopper installed in the hydraulic bush provided with the two fluid chambers is a fluid sealed bush. The hydraulic valve of claim 1, wherein the direction control valve 66 includes upper and lower fluid chambers of the hydraulic bush to improve ride comfort and vibration isolation. Suspension bush control device for a vehicle, characterized in that the connection to the orifice (662) so that the upper, lower fluid chamber (404, 405) flow path of the hydraulic bush is in communication. The vehicle body mounting portion of the lower arm side according to claim 1, wherein the hydraulic bush 40 changes the roll center according to the driving conditions to impart turning stability when turning the vehicle and ensures straightness stability when driving at high speed. While moving the position of the up and down by a predetermined distance, the hydraulic fluid in the upper or lower fluid chambers (404, 405) of the bushing 40, after the orifice (662) is characterized in that it can block the Bushing control device for suspension of automobiles. According to claim 1, wherein the hydraulic components consisting of the relief valve 64, the direction control valves (65) (66), the attenuator (67) is integrated into the hydraulic modulator 60 to minimize the mounting space Suspension bush control device for a vehicle, characterized in that the configuration. According to claim 1, wherein the electric motor (63) controls the operation in order to increase the energy efficiency, characterized in that the control according to the driving conditions obtained by the vehicle speed sensor 71 and the steering angle sensor (72). Bush control device for vehicle suspension.