KR100356866B1 - electronic power steering system in response to velocity for automotive vehicle - Google Patents

Abstract

The present invention relates to a speed-sensitive power steering device for a vehicle, and provides a speed-sensitive power steering device having a relatively simple structure by applying a shear resistance of variable size to a rack bar moving during steering. Its purpose is to.

In order to achieve the above object, the present invention, the steering shaft (2) equipped with a steering wheel (1) for the steering operation of the driver and the drive pinion of the steering shaft (2) is engaged with and receives the operating force therefrom. A power cylinder (5) having a rack bar (5a), and a control valve (4) for supplying hydraulic oil pressurized at a pressure changed according to the vehicle speed to the power cylinder (5) so as to variably adjust the steering force. In the power steering apparatus, the power cylinder (5) is given a shear steering force to the rack bar (5a) to move during steering, so that the degree of shear resistance can be increased in proportion to the vehicle speed of the vehicle being driven. It characterized in that the steering force adjusting means is provided.

Description

Electronic power steering system in response to velocity for automotive vehicle

The present invention relates to a speed-sensitive power steering apparatus for automobiles, and more particularly, to enclose a magnetorheological fluid in the outer circumference of a rack bar moving inside a power cylinder, thereby forming a magnetic field that increases proportionally according to the vehicle speed. The present invention relates to a speed-sensitive power steering apparatus for a vehicle that can adjust steering force according to a vehicle speed by imparting resistance to movement of a rack bar.

In general, a steering device provided in a vehicle is to change the driving direction of a driving vehicle at the driver's will. For this purpose, the steering device is configured to directly steer the driver to transmit the operating force to each device. An operating mechanism comprising a steering wheel, a steering shaft, a column, and the like, a gear mechanism for increasing the operating force by decelerating the rotation of the steering shaft and changing the direction of movement of the operating mechanism to the link mechanism, and forwarding the movement of the gear mechanism. It includes a link mechanism consisting of a pitman arm, a drag link, and a knuckle arm and a tie rod, in order to maintain the position of the right and left wheels at the same time as it transmits to the wheel.

On the other hand, in the case of a large car or a vehicle using low pressure tires, since the grounding resistance of the front wheel is large, the steering force of the steering wheel becomes large and the quick steering operation is not possible. Therefore, the power steering device is used for light and quick steering operation. The same power steering device includes a power device composed of an oil pump for generating hydraulic pressure as a power source, a valve unit including a pressure control valve and a flow control valve, and a hydraulic power generated by the oil pump to generate a steering force. An operating device using a cylinder and a control device for opening and closing the flow path leading to the operation device and controlling the operation direction and operating state of the power cylinder by changing the flow path in accordance with the operation of the handle.

However, in the above-described conventional mechanical steering device or power steering device, the steering feeling felt by the driver is constant according to the vehicle speed, which makes it impossible to simultaneously feel the heavy steering feeling required at high speeds and the light steering feeling at low speeds. There was this.

In order to solve the above-mentioned drawback, the steering force is controlled to be changed according to the vehicle speed, and a speed-sensitive power steering device has been proposed that can give a moderate sense of steering at low speeds and moderate weights at low speeds. Conventional speed-sensitive power steering device detects the vehicle speed of the vehicle being driven by the vehicle speed sensor, and changes the steering force (force for steering) by supplying a corresponding working pressure to the power piston according to the detected vehicle speed. The configuration is complicated because of the complicated hydraulic system and electronics, etc., the structure was complicated, and the manufacturing cost was also expensive.

In addition, the speed-sensitive power steering device forms a reaction chamber at the bottom of the input shaft and a reaction chamber at the lower end of the input shaft and applies pressure to the reaction force plunger by hydraulic pressure passing through the solenoid valve to impart resistance to the input shaft. There is a method of controlling the steering force according to the speed, and as a result, the characteristics of the hydraulic pressure assisted according to the speed of the vehicle tends to increase the distribution of the input torque applied to the steering wheel relative to the output pressure of the cylinder.

In other words, the conventional speed-sensitive power steering device is a flow control method, which inevitably leads to the inhibition of the steering feeling and the generation of noise due to the flow of the fluid having a predetermined pressure. Since this is not possible, there is a disadvantage in that the steering feeling is usually limited to only a few vehicle speed sections.

Accordingly, the present invention has been made in view of the above, and provides a speed-sensitive power steering apparatus having a relatively simple structure by applying a shear resistance of variable size to a rack bar moving during steering. Has its purpose.

The present invention for achieving the above object is a power cylinder having a steering shaft equipped with a steering wheel for steering operation of the driver, a rack bar that is engaged with the drive pinion of the steering shaft and receives the operating force therefrom, and In a power steering apparatus including a control valve for supplying a pressurized hydraulic fluid at a pressure changed according to a vehicle speed to a power cylinder to variably adjust a steering force, wherein the power cylinder has a shear bottom against a rack bar moving during steering. It provides a steering force, characterized in that the steering force adjusting means is provided to increase the degree of the shear resistance force in proportion to the vehicle speed of the running vehicle.

1 is a state diagram showing the configuration of a speed-sensitive power steering apparatus according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a part “I” of FIG. 1;

<Description of Symbols for Main Parts of Drawings>

1-steering handle 2-steering shaft

3-steering column 4-control valve

5-power cylinder 6-oil pump

7-Oil Storage Tanks 8, 9- Supply and Recovery Line

10-tie rod 11-sealing member

12-magnetic fluid 13-magnetic coil

14-control unit 15-vehicle speed sensor

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

1 is a state diagram showing the configuration of a speed-sensitive power steering apparatus according to the present invention, Figure 2 is an enlarged cross-sectional view showing the "a" part of FIG.

As shown in FIG. 1, in the general type of power steering apparatus, the steering speed felt by the driver when steering against the vehicle speed may be proportionally increased.

That is, the present invention is a steering shaft (2) having a steering wheel (1) for steering operation of the driver mounted on the upper end and the steering column (3), which is fixed to the vehicle body by wrapping the steering shaft (2) from the outside, A control valve 4 mounted on the lower part of the steering shaft 2 to control the flow of hydraulic oil during steering, and a driving pin (not shown) provided at a lower end of the steering shaft 2 so as to rotate therein. According to the power cylinder (5) for accommodating the rack bar (5a) in a linear motion, and the engine is connected to the crankshaft and the belt (not shown) by the power is operated from this control when steering It consists of an oil pump (6) to supply the pressurized hydraulic oil to the valve (4), and an oil storage tank (7) for storing a certain amount of hydraulic oil to supply the hydraulic oil to the oil pump (6).

In addition, between the control valve (4), the oil pump (6) and the oil storage tank (7), a supply line (8) and a recovery line (9) for supplying and recovering hydraulic oil are disposed, respectively. Both ends of (5) are exposed to the outside of the other end of the rack bar (5a) in which the internal drive pinion and some sections are engaged, each of which is connected to the front wheel side knuckle arms to the turning direction during steering The tie rod 10 is coupled to push or pull the knuckle arm to rotate.

On the other hand, one side of the power cylinder (5) has a resistance proportional to the vehicle speed against the rack bar (5a) that is engaged with the drive pinion of the steering shaft (2) during steering when linear movement by the operating force transmitted therefrom. By providing, steering force adjusting means for increasing the force required to move the rack bar 5a is provided.

That is, the steering force adjusting means is installed to the outer circumferential surface of the rack bar (5a) accommodated in the interior of the power cylinder (5) and the sealing member 11 is installed to be in close contact between the inner circumferential surface of the power cylinder (5), and the sealing member On the outer circumferential surface of the magnetorheological fluid 12 enclosed in the closed space formed by (11), the rack bar 5a and the power cylinder 5, and the magnetorheological fluid 12 enclosed. The magnetic coil 13 is arranged to surround the circumference thereof and variably adjusts the size of the magnetic field to be formed according to the size of the applied power.

In addition, the steering force adjusting means has a control unit 14 connected to apply a current having a variable magnitude to the magnetic coil 13 according to the vehicle speed detected while driving, and the control unit 14 is being driven. A vehicle speed sensor 15 is provided to detect and input a current vehicle speed of the vehicle.

Accordingly, the vehicle speed sensor 15 detects the vehicle speed while driving and inputs it to the control unit 14, which controls the degree of power applied to the magnetic coil 13 of the steering force adjusting means. The control unit 14 is to increase the intensity of the current applied to the magnetic coil 13 in proportion to the increase in the vehicle speed.

On the other hand, in the steering force adjusting means, a brief feature of the magnetorheological fluid 12 enclosed in the closed space formed by the sealing member 11 and the rack bar 5a in the power cylinder (5) will be described. Is as follows.

The magneto-rheological fluid (12) is a non-colloidal solution in which micron-sized particles are dispersed in a non-conductive solvent such as silicone oil or mineral oil, and the mechanical properties thereof are changed by magnetic field load. As a fluid, a solution in which paramagnetic particles are dispersed in a solvent having a low permeability, and the magnetorheological fluid 12 is formed of a Newtonian fluid having a random structure under no load without a magnetic field. However, once the magnetic field is loaded, the magnetically dispersed particles cause polarization, forming a chain-like fibrous structure in a direction parallel to the loaded magnetic field, thereby reducing the shear force or flow resistance, that is, the shear strain. It is a fluid that is transformed into a Bingham fluid without constant yield shear stress.

In addition, the magnetorheological fluid 12 exhibits isotropic properties due to free movement of particles dispersed in the fluid under no electric field, but induction polarization of particles dispersed in the fluid when the electric field is applied to the electrosensitive fluid. It is a kind of controllable fluid that has a characteristic of exhibiting anisotropic behavior by forming a plurality of fibrous tissues facing the electrode, and thus exhibiting resistance to fluid flow or force from external load. The advantages of the fast response speed of electro-rheological fluids are those that have the disadvantages of low yield stress, narrow operating temperature range, and especially susceptibility to impurities.

Therefore, in the speed-sensitive power steering device including the steering force adjusting means as described above, the control unit 14 detects the vehicle speed of the vehicle being driven through the vehicle speed sensor 15, and then the power cylinder ( A current having a magnitude corresponding to the detected speed of the vehicle is applied to the magnetic coil 13 provided at the outer circumference of 5).

Subsequently, the current applied to the magnetic coil 13 forms a corresponding magnetic field, and the magnetic field thus formed is a magnet enclosed in the sealing member 11 forming a closed space inside the power cylinder 5. The characteristics of the rheology fluid 12 are changed.

As a result, the magnetorheological fluid 12 has a property of a fluid having a shear resistance, and thus, the magnetoheheological fluid 12 is applied from the magnetorheological fluid 12 to the rack bar 5a which the outer circumferential surface of the magnetorheological fluid 12 abuts upon steering. Shear resistance acts.

Therefore, the amount of steering force received by the driver operating the steering wheel 1 during steering increases in proportion to the speed of the vehicle being driven, thereby making it possible to perform a stable steering operation while driving at a relatively low speed. When driving, steering can be performed even with a reduced steering force.

In addition, the speed-sensitive power steering device having a steering force control means using the magnetorheological fluid 12 according to the present invention controls the magnitude of the current compared to the vehicle speed. It is possible to eliminate the occurrence, and because of the characteristics of the current control can be adjusted precisely the steering speed compared to the vehicle speed, it is possible to adjust the individual steering feeling for the various vehicle speed section it is possible to improve the merchandise.

As described above, according to the speed-sensitive power steering apparatus for a vehicle according to the present invention, the vehicle speed is compared with the rack bar 5a of the power cylinder 5 which is linearly moved by the steering force applied to the steering wheel 1. Since it is possible to give a proportional shear resistance force, it is possible to configure a speed-sensitive power steering device having a relatively simple structure.

In addition, due to the configuration of the speed-sensitive power steering device having a simple structure, it is possible to expect not only a reduction in manufacturing cost but also an improvement in assembly productivity.

Claims (3)

Power cylinder (5) with steering shaft (2) equipped with steering wheel (1) for steering operation of driver, and rack bar (5a) which is engaged with driving pinion of steering shaft (2) and receives operating force therefrom. And a control valve (4) for supplying hydraulic power pressurized to the power cylinder (5) at a pressure changed according to the vehicle speed so as to variably adjust the steering force. The power cylinder (5) is provided with a steering force to give a shear steering force to the rack bar (5a) moving during steering, the steering force control means for increasing the proportion of the shear resistance in proportion to the vehicle speed of the running vehicle is provided Speed-sensitive power steering device of the vehicle, characterized in that. The sealing member (11) according to claim 1, wherein the steering force adjusting means is provided to form a closed closed space between the outer circumferential surface of the rack bar (5a) and the inner circumferential surface of the power cylinder (5) within the power cylinder (5). And a magnetorheological fluid 12 enclosed in a closed space formed by the sealing member 11 and the rack bar 5a, and on the outer circumferential surface of the power cylinder 5 in which the magnetorheological fluid 12 is enclosed. A speed-sensitive power steering apparatus for a vehicle, comprising a magnetic coil 13 installed to form a magnetic field of variable size according to a power source. 3. The control unit (14) according to claim 2, wherein said steering force adjusting means includes a control unit (14) for applying a current having a variable magnitude to the magnetic coil (13) in accordance with a vehicle speed detected during driving. The speed-sensitive power steering device for a vehicle, characterized in that the vehicle speed sensor 15 for detecting and inputting the current vehicle speed of the vehicle being driven.