KR20060128204A - Motor-driven steering system equipped with damper structure - Google Patents

Abstract

A motor-driven steering apparatus with a damping apparatus is provided to improve the damping effect of the vibration and noise transferred to the driver and to protect the damping apparatus by installing the damping apparatus using incompressible liquid at the rack bar. A motor-driven steering apparatus with a damping apparatus containing a motor, a rotary sensing unit, and an ECU(Electronic Control Unit) is composed of a gear box(115) covering a rack bar(122) and a pinion; a tube(170) guiding the left and right rectilinear motion of the rack bar; a body fixing unit; a piston unit; oil sealing units(220) interlocked at the tube to cover the rack bar and to prevent the leakage of the oil; left and right oil chambers(D,E) formed between the oil sealing units; left and right tube holes forming a path of the oil; left and right damping units(230) controlling the volume of the oil coming out of the oil chamber; a connection unit(235) connected with the other path of the left and right damping units; and an oil injection unit(260) supplying the oil to the oil chambers, the damping units, and the connection unit.

Description

Motor-driven Steering System Equipped with Damper Structure

1 is a schematic diagram of a conventional motor driven steering device;

2 is a partial cross-sectional view of a conventional rack and pinion type steering apparatus,

3A is a partial cross-sectional view of a motor driven steering device using the damping device according to the first embodiment of the present invention;

3B is a partial detailed cross-sectional view of the damping unit and the oil injection unit of the motor-driven steering apparatus using the damping device according to the first embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: steering wheel 101: steering shaft

110: pinion 115: gearbox

120: electronic control unit 122: rack bar

130: motor 140: motor gear

150: rotation detection unit 160: steering shaft gear

170: tube 180: body connection

190: Tie Rod 191: Knuckle Arm

192: kingpin 193: wheels

210: piston 220: oil sealing part

230: attenuation part 235: connection part

260: oil injection unit 290: pressure gauge

310: injection section spring 320: injection section plug

330: spring stage 340: injection unit body

351: bulkhead 352: damping spring

353: inner housing 354: outer housing

362: microhole 361: main hole

  C: Administrative division D: Left chamber

  E: Right Chamber

The present invention relates to a motor driven steering device using a damping device. More particularly, the present invention relates to a steering apparatus using a damping device installed in a tube to absorb vibrations and noises coming from a steering wheel along a tire, knuckle arm, tie rod, rack bar, pinion, and steering shaft.

Various devices are installed in the vehicle for improving the safety of the vehicle and for the convenience of the driver. Among them, the steering device is a device that allows the driver to turn the steering wheel to change the driving direction of the vehicle to the desired direction. In other words, the steering apparatus is a device that assists the driver in advancing the vehicle in a desired direction by arbitrarily changing the rotation center of rotation of the front wheel of the vehicle.

The steering system is closely related to the front axle or front wheel alignment in the case of a front-wheel drive vehicle and is a very important device that is responsible for the safety of driving the vehicle together with the braking system. To steer the wheel while the vehicle is stationary, the driver must apply more than a certain amount of force to the steering system because more force must be applied than the friction between the wheel and the road surface. In general, when the weight of the vehicle is large and the width of the wheel is large, the frictional force with the road surface increases, which makes it difficult to operate the steering system. In this case, a power steering system is generally added to reduce the driver's power. Generally, a power steering device includes hydraulically driven steering devices and motor driven steering devices.

The hydraulically driven steering system receives hydraulic power from the engine to operate the hydraulic pump and relieves the operator's power by sending the hydraulic pressure produced by the hydraulic pump to the driven piston at the right amount in a timely manner according to the rotation of the steering wheel or steering shaft. give.

The motor-driven steering device detects the rotation of the steering wheel or the steering shaft and is installed on the rack bar or the steering shaft to operate a motor that assists the rotational movement so that the steering device operates smoothly by moving the rack bar. Motor-driven steering systems are largely rack-driven (R-EPS: Rack-Electric Power Steering) and steering-axis drive (C-EPS: Column-Electric Power Steering).

On the other hand, the type of changing the steering shaft rotational motion to the linear motion of the rack bar is classified into rack and pinion type steering device and ball and nut type steering device.

The dual rack-and-pinion steering system has a structure in which the steering wheel directly responds to the movement of the steering wheel because the movement of the pinion gear directly connected to the steering shaft is directly transmitted to the rack bar. It is widely used in all-wheel drive vehicles of small cars, and rotational force is transmitted to the gearbox consisting of rack bars and pinion gears through universal joints and hook joints generally included in the steering shaft, and the rotation of the steering shafts by rack bars and pinion gears. The movement is converted to the linear movement of the rack bar.

1 is a schematic diagram of a conventional motor-driven steering apparatus. As shown, the motor-driven steering device includes a steering wheel 100, a steering shaft 101, a pinion 110, a rack bar 122, a tube 170, a vehicle body fixing unit 180, a gear box 115, Tie rod 190, knuckle arm 191, king pin 192, wheels 193, rotation sensing unit 150, electronic control unit 120, motor 130, motor gear 130 and steering shaft gear And 160.

The steering shaft 101 is provided with a steering shaft gear 160, the motor 140 is installed a motor gear 140, the steering shaft gear 160 and the motor gear 140 has a constant gear ratio and each gear The teeth engage and combine. Therefore, the steering shaft 160 rotates when the motor 130 rotates.

One side of the steering shaft 101 is configured with a rotation detecting unit 150 for detecting a rotation, the rotation detecting unit 150 sends a rotation signal of the steering shaft to the electronic control unit 120. The electronic control unit 120 includes a control function for analyzing the rotation signal sent from the rotation detection unit 150 to drive the motor 140 in a timely manner.

The gear box 115 installed on the other side of the steering shaft 101 has a structure in which the gear teeth of the pinion 110 and the rack bar 122 are engaged with each other and are coupled to each other. As a result, the rotational movement of the pinion 110 is the rack bar 122. To be converted to linear motion. The tube 170 having a hollow shaft shape surrounds the rack bar 122 in the axial direction to guide the linear movement of the rack bar 122 and is fixed to the vehicle body by the vehicle body fixing part 180. Accordingly, the left and right linear movements of the rack bar 122 along the tube 170 are eventually transferred to the knuckle arm 191 including the tie rod 190 and the wheels 193, and the wheels 193 around the kingpin 192. To be steered.

That is, the motor-driven steering device receives a signal from the rotation sensing unit 150 attached to the steering shaft 101 to operate the motor 130 connected to the steering shaft 101 to eventually apply a force to the steering shaft 101. The pinion 110 is rotated and the rack bar 122 is linearly moved along the tube 170 so that the steering device is operated. In other words, in the motor-driven steering device, the motor 130 reduces the driver's power by allowing the pinion 110 to rotate smoothly.

In general, when the vehicle passes a protruding or recessed road surface when driving at a high speed, the noise and vibration transmitted to the wheel 193 when the wheel 193 is impacted are knuckle arms 191, tie rods 190, and rack bars. There is a problem transmitted to the driver through the 122, the pinion 110, the steering shaft 101, the steering wheel 100 (commonly referred to as "kickback phenomenon").

In addition, when the vehicle travels at a high speed, even when the vehicle passes a smooth road surface, the steering apparatus together with the wheels 193 generate vibrations. In particular, even when the wheel 193 has a perfect center of gravity, when the vehicle having a heavy weight runs at a high speed, the wheel is deformed at its outer circumferential surface, so that the center of gravity changes at high speed, thereby generating vibration. Also called "similar phenomenon"). The vibration generated by these factors is eventually transmitted to the driver through the knuckle arm 191, tie rod 190, rack bar 122, pinion 110, steering shaft 101 and the steering wheel 100 to the driver There is an unpleasant problem.

2 is a partial cross-sectional view of a conventional rack and pinion type steering apparatus. As shown, when the gear teeth of the rack bar 122 and the pinion 110 are engaged, the rack bar 122 moves in the direction (A) when the pinion 110 rotates due to the geometric shape of the thread (B). Vertical component acts in the direction. In the worst case, it is preferable that the rack bar 122 and the pinion 110 are firmly coupled to each other to prevent the case from being separated from each other.

On the other hand, it is common to minimize the play to minimize back-lash between the gear teeth of the pinion 110 and the gear teeth of the rack bar 122. Accordingly, some noise and vibration transmitted from the tire 193 to the rack bar 122 are not only firmly fixed to each other and coupled to the play, but also the pinion 110, the steering shaft 101, and the steering wheel 100. There is a structural problem that is conveyed to the driver through.

Meanwhile, when the steering wheel 100 is rotated, the motor 130 rotates to rotate the steering shaft 101 so that the pinion 110 rotates and the rack bar 122 linearly moves while the linear motion of the rack bar 122 is steered. It has a structure that is hard to be converted to rotational movement of the axis.

In other words, the vibration and noise transmitted to the rack bar through the wheels are not all transmitted to the steering wheel, but are partially absorbed by the gear bar of the rack bar and the gear of the pinion, causing wear between the gear teeth. The gap between the liver produces another vibration and noise. In addition, there is a problem in that the backlash is increased due to the play between the rack and the pinion gear teeth, so that power transmission is not smooth.

In order to solve the above problems, the present invention provides a steering apparatus having a damping unit installed in the tube to absorb the vibration and noise coming from the tire, knuckle arm, tie rod, rack bar, pinion, steering shaft, steering wheel.

In order to achieve this object, the present invention provides a motor installed to assist the driver's operating force of the steering wheel in a steering device that transmits the rotation of the steering wheel to a steering shaft, pinion, rack bar, tie rod, knuckle arm and tire in a vehicle. In the motor-driven steering apparatus including a rotation sensing unit installed on the steering shaft to detect the rotation of the steering shaft, an electronic control unit for analyzing the rotation signal sent from the rotation sensing unit to send a drive signal to the motor, A gearbox surrounding the rack bar and the pinion to prevent the pinion and the rack bar from being separated from each other; A tube having a hollow shape for accommodating the rack bar and guiding the linear motion of the rack bar; A vehicle body fixing part for fixing the gear box and the tube to the vehicle body; A piston part fixed to the rack bar when the rack bar moves in a linear direction to the left and a relative piston motion with the tube fixed to the vehicle body; An oil sealing part fixed to the tube on both sides of the piston in the axial direction of the tube and tightly attached to the rack bar and interlocked with the tube to prevent leakage of oil while wrapping the rack bar when the rack bar moves left and right linearly; Left and right oil chambers formed between the oil sealing portions on both sides of the piston in the tube; Left and right tube holes which are processed in the direction of the outer circumferential surface of the tube in the left and right oil chambers to form a flow path of oil; Left and right damping parts connected to the left and right tube holes to control an amount of oil from the oil chamber; A hollow pipe shape, the connecting portion connected to the other side flow path of the left and right damping portion; And an oil injecting unit supplying oil to the left and right oil chambers, the left and right attenuating units, and the connecting unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

3A is a partial cross-sectional view of a motor driven steering device using the damping device according to the first embodiment of the present invention. As illustrated, the rack bar 122, the piston 210, the oil sealing part 220, the damping part 230, the left chamber D, the right chamber E, the oil connecting part 215, the oil filling part 260 And a hydraulic system 290.

As shown in the figure, a long cylindrical rack bar 122 is a shape in which the hollow tube 170 is wrapped, and the tube 170 is fixed to the vehicle body by the vehicle body fixing part 180. The rack bar 122 moves left and right along the inside of the tube 170 fixed to the vehicle body. When the steering wheel 100 is rotated to the left, the rack bar 122 moves to the right and the wheel is steered to the left and the steering wheel 100 is rotated. Rotate) to the right to move the rack bar 122 to the left and to steer the wheels to the right.

The piston 210 is formed and fixed on the outer circumferential surface of the rack bar 122 in a ring shape, and has a structure that is in close contact with the inner surface of the tube 170 to slide. When the wheel 193 is in a straight line toward the front of the vehicle, that is, when the steering wheel 100 is rotated to the left as far as possible in the neutral state of the steering device, the piston 210 moves to the maximum right. When the piston 100 is rotated to the right as far as possible, the piston 210 moves to the maximum left. The maximum right section from the maximum left portion of the piston 210 is referred to as a stroke section (C). Each of the left and right points away from the administration section C is fixed in close contact with the tube 170, the sliding bar bar 122, and the left and right oil sealing parts 220 having a ring shape having a leakage preventing function are installed. Therefore, the left chamber D is formed between the piston 210 and the left oil sealing part 220, and the right chamber E is formed between the piston 210 and the right oil sealing part 220.

In the left chamber (D), a tube hole is formed in the tube 170 in the direction of the outer circumferential surface from the center of the longitudinal cross section of the hollow tube 170, and the hole is connected to one side flow path of the right attenuation part 230. In the chamber E, the tube hole is also machined in the tube 170 from the center of the longitudinal cross section of the hollow tube 170 to the outer circumferential direction, and one channel of the left attenuator 230 is connected to the tube hole. That is, one side of the left and right attenuator 220 is connected to the tube hole configured in the tube 170, and the other side flow paths of the left and right attenuator 230 are connected to each other by the connection unit 235. The connection part 235 connecting the other side flow path of the left and right attenuation part 230 is configured to include an oil injection part 260 and a pressure gauge 290 at one side in a hollow form a continuous flow path therein.

The piston 210, which is interlocked with the rack bar 122 and is in close contact with the tube 170, is moved to the right side when the steering wheel 100 rotates counterclockwise. Therefore, as the space of the right chamber E is reduced, the oil having incompressible characteristics is the right tube hole formed in the right chamber E, the right side attenuator 230, one side flow path, the right attenuator 230, and the right attenuated oil. The other side flow path 230, the connection part 235, the left side damping part 230, the other side flow path, the left side damping part 230, the left side damping part 230, one side flow path, and the left tube hole formed in the left chamber D. Move to the right chamber (E). That is, the oil of the right chamber (E) is to move to the left chamber (D). Likewise, when the steering wheel 100 rotates clockwise, the oil in the left chamber D moves to the right chamber E.

3B is a partial detailed cross-sectional view of the damping unit and the oil injection unit in the steering apparatus having the damping unit according to the first embodiment of the present invention. As illustrated, the damping part includes an outer housing 354, a partition 351, a microhole 362, an inner housing 353, a damping spring 352, and a main flow path 361, and includes an oil injecting part ( 260 includes an inlet spring 310, a stopper 320, and a spring end 330, and the connection 235 includes a pressure gauge 290 that checks the pressure of the oil.

As shown in the drawing, the left attenuator 230 includes an outer housing 354 having an opening cross-sectional area whose inner diameter gradually narrows from one side to the other side, and one side flow path of the outer housing 354 is a hole formed in the left chamber D. The other flow path is connected to the connecting portion 235. The inner housing 353 is installed in the inner empty space of the outer housing 354. The main hole in which one side is completely opened and the other side is blocked but the other side is blocked in a hollow column form from one side of the left attenuator 230 to the other side Has (361). The outer circumferential surface of the outer housing 354 has a main hole 361 of the inner housing 353 while the outer housing 354 slides from one side to the other side or the other side to one side according to the flow of oil coming from one side and the other side. And flow path cross-sectional area changing means for changing the cross-sectional area of the inner opening of 354. The inner housing 353 has a partition wall 351 fixed to the outer housing 354, and the partition wall 351 has one or more micro holes 362 through which some oil can pass. One side of the inner housing 353 is fully perforated toward the partition wall 351, and the damping spring 352 installed on the partition wall 351 uses the partition wall as an end to move the inner housing 353 to the main hole 361 side. The structure is hard. Accordingly, the left damping unit 230 may close the main hole 362 and the micro holes 362 of the partition wall even when the inner housing 353 blocks the inner oil passage of the outer housing 354 by the elastic force of the damping spring 352. It also has a structure that allows oil to flow through (the right attenuator has the same structure).

As shown in Figure 3b, the oil injection portion 260 is made of a connection portion 235 hole to be the injection path of oil, the inner diameter is larger than the connection portion 235 hole, one side is completely open and the other side is blocked but has a hole in the center The injection part body 340 is formed by tightly fixing one side to the connection part 235 hole. An injection part spring 310 is installed at a spring end 330 formed by a difference between an inner diameter of the connection part 2350 and one inner diameter of the injection part body 340, and the injection part spring 310 is an injection part body 340. The stopper 320 has a structure in which the stopper 320 blocks the other side hole of the injection part body 340 by holding the injection part stopper 320 blocking the hole formed in the other center part of the bottom side in the opposite direction of the spring end 330. Therefore, when oil is injected into the oil injection part 260, the oil which has overcome the elasticity of the injection part spring 310 pushes the injection part stopper 320, and oil is injected, and after the injection of oil is completed, the injection part is again. The injection portion cap 320 is pushed out by the elastic force of the spring 310 to seal the oil injection portion 260.

Therefore, by injecting oil using the oil injecting unit 260, the left chamber D, the right chamber E, the left and right attenuating unit 230, and the connecting unit 235 are filled with oil having a predetermined viscosity or incompressibility. You lose. In addition, it will be possible to add a function that allows the pressure gauge 290 to check the appropriateness of the pressure.

When the steering device is not operated, since the damping part 230 blocks the oil passage having the opening cross-sectional area where the inner housing 354 is narrowed by the elastic force of the damping spring 352, most of the oil is fine in the partition 351. It must flow through the hole 362 to the main hole 361, but the amount of oil that can pass per hour has a structure that is determined by the micro holes 362.

When the rack bar 122 moves to the left, the left damping portion 230 acts as a damping, but the right damping portion 230 is only a flow path of oil introduced through the connecting portion 235 in the left chamber (D). When the rack bar 122 moves to the right side, the right damping part 230 of the rack bar 122 may increase the cross-sectional area of the inner opening of the outer housing 354 from the inner housing 353 of the right damping part 230. Oil is pushed in the direction 235 is formed on the other outer peripheral surface of the inner housing (353) along the other flow path of the damping unit 230, the space is large enough to pass the oil there is little damping action. Similarly, when the rack bar 122 moves to the right side, the right attenuation part 230 acts as attenuation, and the left attenuation part 230 is merely a flow path. That is, when the rack bar 122 moves to the left, the left attenuator 230 acts as attenuation, and when the rack bar 122 moves to the right, the right attenuator 230 acts as the attenuation.

If the diameter of the microholes 362 among the components of the left and right attenuators 230 is small, the flow of oil is reduced. Accordingly, the movement speed of the piston 210 is also reduced. In other words, the flow rate of the oil flow of the damping unit 230 and the movement speed of the rack bar 122 is in proportion. Therefore, when the size of the microholes 362 is small, the movement speed of the rack bar 122 is reduced. In this principle, the damping unit 230 for limiting the movement speed of the rack bar 122 not only attenuates the vibration having a high speed transmitted to the rack bar 122, but also has a function of softening the operating feeling of the steering device.

The vibration energy of the rack bar is absorbed by the damping part, which reduces the vibration energy leading to the rack bar, pinion, steering shaft, and steering wheel, as well as the vibration of the rack bar is attenuated, thereby reducing the wear between the rack bar gear and the pinion gear teeth. As a result, the vibration and noise caused by the play produced when the rack bar and pinion are driven are also reduced.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, the motor-driven steering device using the damping device is provided by providing a damping device using an incompressible fluid in the rack bar. It effectively attenuates vibration and noise transmitted to the driver through the gearbox, steering shaft, and steering wheel, and protects the steering system, providing a safer driving environment and preventing steering system failure.

Claims (3)

A motor installed to assist the driver's operating force of the steering wheel in a steering device that transmits the rotation of the steering wheel to a steering shaft, pinion, rack bar, tie rod, knuckle arm, and tire, and to detect the rotation of the steering shaft. In the motor-driven steering apparatus including a rotation sensing unit installed on a steering shaft, an electronic control unit for transmitting a driving signal to the motor by analyzing the rotation signal sent from the rotation sensing unit, A gearbox surrounding the rack bar and the pinion to prevent the pinion and the rack bar from being separated from each other; A tube having a hollow shape for accommodating the rack bar and guiding the linear motion of the rack bar; A vehicle body fixing part for fixing the gear box and the tube to the vehicle body; A piston part fixed to the rack bar when the rack bar moves in a linear direction to the left and a relative piston motion with the tube fixed to the vehicle body; An oil sealing part fixed to the tube on both sides of the piston in the axial direction of the tube and tightly attached to the rack bar and interlocked with the tube to prevent leakage of oil while wrapping the rack bar when the rack bar moves left and right linearly; Left and right oil chambers formed between the oil sealing portions on both sides of the piston in the tube; Left and right tube holes which are processed in the direction of the outer circumferential surface of the tube in the left and right oil chambers to form a flow path of oil; Left and right damping parts connected to the left and right tube holes to control an amount of oil from the oil chamber; A hollow pipe shape, the connecting portion connected to the other side flow path of the left and right damping portion; And An oil injection part supplying oil to the left and right oil chambers, the left and right attenuation parts, and the connection part Motor-driven steering apparatus having a damping device comprising a. The oil injection unit of claim 1, It includes a connection hole formed in the connection portion for injecting the oil and has a pipe shape having an inner diameter larger than the diameter of the connection hole, one side is drilled and the other side has a hole formed in the center portion and the one side is tightly fixed to the connection hole Injection body; A spring end formed between one side inner circumferential surface of the injection part body and an inner circumferential surface of the connection hole; A stopper for blocking the hole formed at the center of the other side of the injection part body; And An injection part spring installed at the spring end to hold the stopper toward a hole formed at the other side of the injection part body; Motor-driven steering apparatus having a damping device comprising a. The method of claim 1, wherein the attenuation unit, An outer housing having oil passages on one side and the other side, the one side of which is connected to the tube hole, the other side of which is connected to the connecting portion, the inside of which is hollow and whose opening cross-sectional area gradually narrows from the tube hole side to the connecting portion; A partition wall formed at a tube hole side of the outer housing to form a stage; At least one microhole formed in the partition wall in the direction of the connecting portion from the tube hole side; An inner housing in which the inside is hollow in a pipe shape, one side of which is drilled, and a main hole is formed in the other center portion, the one side of which is installed in the direction of the partition wall, and the other side of which is installed in an opening cross-sectional area direction in which the inner diameter of the damping portion is narrowed; And A damping spring provided on the partition wall and holding the inner housing in a direction of an opening cross-sectional area where the inner diameter of the damping portion is narrowed; Motor-driven steering apparatus having a damping device comprising a.

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