KR20140100011A - Steering system for vehicle - Google Patents

Abstract

A hydraulic steering part for performing power steering via hydraulic pressure; A torque distributor provided on the steering shaft and providing torque to the steering shaft via the motor; And when the automatic steering function of the vehicle is requested, the torque providing unit is driven and controlled. When the vehicle is in the low speed range, the torque providing unit is driven in accordance with the input torque of the driver, And a control section for driving the torque providing section in accordance with the steering angle velocity to provide a damping torque for the steering.

Description

[0001] STEERING SYSTEM FOR VEHICLE [0002]

The present invention relates to a steering system of a vehicle in which the basic rack thrust is generated by hydraulic pressure and, if necessary, assists the torque by the motor in some cases.

The conventional hydraulic power steering has a problem in that the automatic steering function can not be implemented because the tire is rotated only by the force generated from the fluid, so that it can not be controlled in cooperation with other systems. In other words, since the hydraulic system transmits the force only when the torsion bar is twisted and the valve is opened, power transmission to the gear box is impossible without the driver's steering.

On the other hand, in the case of other system cooperative control cases requiring automatic steering, the following cases can be mentioned.

1) Parking assist system: A system that allows the driver to park the vehicle automatically without recognizing the surroundings by sensors

2) Lane keeping system: A lane keeping system that allows the lane to be automatically maintained even when the driver does not steer by recognizing the lane by sensor etc.

3) Chassis integrated control system: Reduces vehicle risk by automatically steering in the required direction automatically at dangerous moments of the vehicle (when the vehicle turns on asymmetric friction roads)

In addition, since the hydraulic control system is not equipped with electronic control (automatic steering function), it is inevitable that the steering performance deteriorates (it is impossible to implement steering assist force, restoration, and pulling compensation function by vehicle speed).

In the meantime, since the conventional electric power steering (MDPS) rotates the tire only by the force generated from the motor, the size of the motor and the deceleration mechanism portion have to be developed in order to satisfy the total rack thrust. In order to mount the MDPS, There is a problem that the loss of the investment cost of the vehicle is largely generated.

Also, since it is always located close to the driver, it has a great influence on the collision performance of the vehicle according to the size.

In addition, while the hydraulic system assists the steering force smoothly by the continuous flow of the hydraulic fluid, there is a problem that the MDPS causes artificial steering sensation due to the disconnection of the motor and the ECU, and the cushioning torque, torque ripple, .

As a result of such various problems, attempts have been made recently to integrate a hydraulic type and an electronic type. Typically, the conventional KR10-2010-0072906 A "MDPS and EHPS parallel steering system for vehicle" And more particularly, to a steering apparatus for a vehicle-mounted MDPS and EHPS capable of performing complementary functions by steering the MDPS and the EHPS in parallel and securing safety by providing auxiliary steering force in case of emergency steering failure The EHPS for assisting the steering power with the hydraulic pressure generated by the driving of the hydraulic pump and the ECU for controlling the driving of the main motor and the hydraulic pump, , Using the MDPS as the main steering and using the EHPS as the auxiliary steering to disable the emergency steering of the motor Or assist steering assist force which is insufficient in a large-sized vehicle. "

However, according to this conventional technique, the steering force is added by using the motor of the MDPS as the main steering mechanism, but the problem of the heterogeneity of the steering and the inability of the automatic steering function is still present by using the hydraulic type only as auxiliary.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

KR 10-2010-0072906 A

The present invention has been proposed in order to solve such problems, and provides a steering system of a vehicle which is combined with a hydraulic type and an electric type, secures a steering feeling by using a hydraulic type, It has its purpose.

According to an aspect of the present invention, there is provided a steering system for a vehicle, including: a hydraulic steering unit for performing power steering via hydraulic pressure; A torque distributor provided on the steering shaft and providing torque to the steering shaft via the motor; And when the automatic steering function of the vehicle is requested, the torque providing unit is driven and controlled. When the vehicle is in the low speed range, the torque providing unit is driven in accordance with the input torque of the driver, And a control unit for driving the torque providing unit according to the steering angle speed to provide a damping torque for the steering.

The automatic steering function of the control unit may include an automatic parking function, a car line holding function, and a chassis safety control function.

The control unit may increase the steering torque to be added in accordance with the input torque of the driver when the vehicle is in the low speed section.

The maximum value of the added steering torque can be limited to a certain value.

The added steering torque can be increased as the vehicle speed is lower.

The control unit includes a data map for inputting an input torque of the driver and outputting an increase in steering torque according to the input torque. The slope of the steering torque according to the input torque can be increased as the vehicle speed is lower.

The maximum value of the steering torque is limited to a constant value, and the steering torque can be converged to a maximum value at a smaller input torque as the vehicle speed is lower.

The controller may increase the damping torque according to the increase of the steering angle velocity when the vehicle is in the low speed section.

The damping torque may be such that the maximum value is limited to a certain value.

The damping torque can be increased as the vehicle speed is higher.

The control unit includes a data map that receives the driver's steering angle velocity and outputs damping torque that increases according to the steering angle velocity. The slope of the damping torque according to the steering angle velocity can be increased as the vehicle speed is higher.

The maximum value of the damping torque is limited to a predetermined value, but the maximum value increases as the vehicle speed increases, and converges to a maximum value at a smaller steering angle velocity as the vehicle speed increases.

According to the vehicle steering system constructed as described above, in the case of the hydraulic steering, the entire steering rack thrust necessary for the vehicle is handled, so that the conventional power steering function can be performed without driving the torque control motor.

Therefore, steering feeling is improved compared to the existing MDPS.

At the same time, the torque control motor provides the minimum automatic steering torque for the automatic steering function and the coordinated control. It provides the minimum performance control torque to improve the hydraulic steering performance, thereby reducing the overall size by providing the minimum torque, Improvement and mounting are facilitated.

1 is a configuration diagram of a steering system of a vehicle according to an embodiment of the present invention;
Figures 2, 4, and 6 are flowcharts illustrating an implementation of a steering system of a vehicle in accordance with an embodiment of the present invention.
Figures 3 and 5 are examples of data maps for the implementation of a steering system of a vehicle in accordance with an embodiment of the present invention.

Hereinafter, a vehicle steering system according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a steering system of a vehicle according to an embodiment of the present invention, FIGS. 2, 4, and 6 are flowcharts for implementing the steering system of a vehicle according to an embodiment of the present invention, 5 is an illustration of a data map for implementation of a steering system of a vehicle in accordance with an embodiment of the present invention.

As shown in FIG. 1, the steering system of the vehicle of the present invention includes a hydraulic steering part 100 for performing power steering via hydraulic pressure; A torque providing unit 200 provided on the steering shaft and providing torque to the steering shaft via the motor 220; And when the automatic steering function of the vehicle is requested, the torque providing unit 200 is driven and controlled. When the vehicle is in the low speed section, the torque providing unit 200 is operated in accordance with the input torque of the driver And a control unit 300 that drives the torque providing unit 200 to add a steering torque or drives the torque providing unit 200 according to the steering angle speed to provide a damping torque for steering.

The steering system of the vehicle of the present invention is basically provided with a hydraulic steering part 100 that provides a rack thrust to the steering mechanism through a hydraulic pressure providing part that provides hydraulic pressure by the power of the motor or the engine like a conventional hydraulic steering system.

And a torque providing unit 200 provided on the steering shaft to provide a torque to the steering shaft via the motor 220 so that the hydraulic power steering can be operated with greater strength.

Accordingly, the torque providing unit 200 is normally stopped and the steering of the vehicle is performed only through the hydraulic steering unit 100, thereby realizing the function of power steering. In such a system, it is general that the rack thrust is generated due to the hydraulic pressure by opening and closing the valve according to the torsion of the torsion bar when the driver steers.

By adopting such a hydraulic steering part 100 as a basic steering system, it is possible to overcome the steering unevenness which is a disadvantage of the conventional MDPS system and to improve the commerciality such as torque ripple.

On the other hand, the control unit 300 selectively drives the torque providing unit 200 only when necessary, which allows the steering to intervene only for a short time in a very unusual situation unlike the usual case. Accordingly, through the control of the motor 220, a smooth and continuous steering due to the hydraulic pressure is possible at normal times, and a steering torque by the motor 220 is added only when necessary, thereby satisfying the commerciality and stability of the vehicle at the same time . The control unit 300 can be installed together with the motor 220 and can be installed separately from the motor 220. The control unit 300 can also be mounted on the vehicle in accordance with its functions.

More specifically, the control unit 300 controls the torque providing unit 200 to be operated when the automatic steering function of the vehicle is requested, The control unit 200 drives the torque providing unit 200 according to the input torque of the driver to add a steering torque or drives the torque providing unit 200 according to the steering angle speed to provide a damping torque for steering.

2 shows control of the automatic steering function of the steering system of the vehicle according to the present invention.

For example, the automatic steering function of the control unit 300 may include an automatic parking function, a car line holding function, and a chassis safety control function, for example. .

Specifically, the automatic parking function recognizes the surroundings of the vehicle by means of a sensor and the like so that the driver can automatically park the vehicle without steering, which requires automatic steering. So that the lane can be maintained automatically even if the driver does not steer, and the control actively intervenes in the steering. In addition, the chassis safety control function refers to a function of automatically reducing the risk of a vehicle by steering in a required direction automatically at a dangerous moment (when the vehicle is turned on an asymmetric friction surface) of the vehicle.

In addition, when various kinds of automatic steering are required, the control unit 300 drives the torque providing unit 200 to provide the steering torque necessary for the automatic steering. Therefore, while maintaining the advantage of hydraulic steering at normal times, at the same time, it is necessary to automatically steer only when necessary to ensure the merchantability.

First, in the vehicle, an initial check is performed to check whether an electrical component is abnormal (S10), a warning is performed (S12), an engine is checked (S20), and if automatic steering is required during traveling (S100) (S200).

3 and 4 relate to a method for doubling the steering torque so that heavy steering can be moved more lightly in low speed situations such as during parking or reversing.

That is, when the vehicle speed is a low speed condition such as 30KM / H, the torque providing unit is selectively driven to achieve a smoother and smoother steering feeling.

This is a concept of variable speed control according to vehicle speed, which increases the steering torque according to the motor of the torque providing part in accordance with the input torque applied to the steering wheel by the driver, thereby providing power steering at the low speed by the hydraulic pressure and the motor.

Therefore, the driver is provided with the stable steering according to the hydraulic type at high speed, and the light and smooth steering can be felt at the low speed.

In particular, in this case, the control unit increases the steering torque to be added in accordance with the input torque of the driver when the vehicle is in the low-speed section, and the maximum value of the added steering torque is limited to a certain value. That is, basically, since the rack thrust by the hydraulic pressure is provided, the torque and the design size of the torque-providing portion can be greatly reduced by restricting the maximum value constantly, It is possible to secure more space in the knee and increase the freedom of design and safety.

And the steering torque to be added is increased as the vehicle speed is lower.

That is, as shown in FIG. 3, the control unit includes a data map for inputting the input torque of the driver and outputting an increase in steering torque according to the input torque. The slope of the steering torque according to the input torque increases as the vehicle speed is lower .

Further, the steering torque is limited to a constant value, and the steering torque converges to a maximum value at a smaller input torque as the vehicle speed is lower, thereby increasing the steering torque to be added more quickly as the vehicle speed is lower, So that they can work more easily and quickly.

In this case, if the vehicle speed is equal to or lower than the reference vehicle speed (S300) as shown in FIG. 4, steering is made easier and lighter by the concept of steering torque assist (S400).

5 and 6 are related to the damping control. When the angular velocity of the steering is large, damping is performed in the form of reverse torque, whereby more accurate and linear steering operation is possible and the steering stability of the vehicle is secured .

More specifically, in this case, when the vehicle speed is equal to or lower than the reference vehicle speed (S500), damping control of the motor is performed through the torque providing unit to implement the damping effect on the steering torque (S600).

In this case, the control unit increases the damping torque in accordance with the increase of the steering angle velocity when the vehicle is in the low-speed section, thereby providing stability when the steering is changed rapidly.

Also, the damping torque can be reduced by limiting the maximum value of the damping torque to a constant value, and the damping torque can be increased as the vehicle speed is increased. Thus, as the vehicle speed is fast in the low- To increase the torque.

That is, the control unit has a data map that receives the driver's steering angle velocity and outputs damping torque that increases according to the steering angle velocity, and the slope of the damping torque according to the steering angle velocity increases as the vehicle velocity increases.

However, the maximum value of the damping torque is limited to a certain value, but the maximum value increases as the vehicle speed increases, and the upward slope can be adjusted by converging to a maximum value at a smaller steering angle speed as the vehicle speed is higher.

According to the vehicle steering system constructed as described above, in the case of the hydraulic steering, the entire steering rack thrust necessary for the vehicle is handled, so that the conventional power steering function can be performed without driving the torque control motor. Therefore, steering feeling is improved compared to the existing MDPS.

At the same time, the torque control motor provides the minimum automatic steering torque for the automatic steering function and the coordinated control. It provides the minimum performance control torque to improve the hydraulic steering performance, thereby reducing the overall size by providing the minimum torque, Improvement and mounting are facilitated.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims It will be apparent to those of ordinary skill in the art.

100: Hydraulic steering part 200:
300:

Claims (12)

A hydraulic steering part 100 for performing power steering via hydraulic pressure;
A torque providing unit 200 provided on the steering shaft and providing torque to the steering shaft via the motor 220; And
The torque providing part 200 is driven when the automatic steering function of the vehicle is requested, and when the vehicle is in the low speed section, the torque providing part 200 is not driven, And a control unit (300) for driving the supplying unit (200) to add a steering torque or to drive the torque providing unit (200) in accordance with the steering angle speed to provide a damping torque for the steering. The method according to claim 1,
Wherein the automatic steering function of the controller (300) includes an automatic parking function, a car line holding function, and a chassis safety control function. The method according to claim 1,
Wherein the control unit (300) increases the steering torque to be added in accordance with the input torque of the driver when the vehicle is in the low speed range. The method of claim 3,
Wherein the added steering torque is limited to a maximum value. The method of claim 3,
Wherein the added steering torque is increased as the vehicle speed is lower. The method according to claim 1,
The control unit 300 includes a data map for inputting an input torque of the driver and outputting an increase in steering torque according to the input torque, and the slope of the steering torque according to the input torque is increased as the vehicle speed is lower The steering system of the vehicle. The method of claim 6,
Wherein the steering torque is limited to a maximum value and the steering torque converges to a maximum value at a smaller input torque as the vehicle speed is lower. The method according to claim 1,
Wherein the controller (300) increases the damping torque according to an increase in the steering angle velocity when the vehicle is in a low speed section. The method of claim 8,
Wherein the maximum value of the damping torque is limited to a predetermined value. The method of claim 8,
Wherein the damping torque is increased as the vehicle speed is higher. The method according to claim 1,
The control unit 300 has a data map that receives the driver's steering angle velocity and outputs damping torque that increases according to the steering angle velocity. The slope of the damping torque according to the steering angle velocity increases as the vehicle velocity increases. The steering system of the vehicle. The method of claim 11,
Wherein the maximum value of the damping torque is limited to a predetermined value, but the maximum value increases as the vehicle speed increases, and converges to a maximum value at a smaller steering angle velocity as the vehicle speed increases.

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