Safety apparatus for steer-by-wire

The present invention relates to a safety apparatus for a steer-by-wire. The present invention can ensure the safety of a steer-by-wire using a simple and compact structure and achieve a manufacturing-cost reduction effect.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2014-0045266, filed on Apr. 16, 2014, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a safety apparatus for a steer-by-wire and, more specifically, to a safety apparatus for a steer-by-wire that can ensure the safety of a steer-by-wire using a simple and compact structure and can be manufactured at a low cost.

2. Description of the Prior Art

A steer-by-wire (SBW) refers to an apparatus that controls steering using hydraulic pressure or auxiliary electric power only through an electric signal instead of a mechanical structure connecting the rotation of a steering wheel and the rotation of wheels.

The SBW generally includes a steering angle sensor on a steering input side thereof and a steering output sensor and a steering actuator on a steering output side thereof. The steering angle sensor detects a steering angle, the steering output sensor detects the rotation angle of a wheel, and the steering actuator generates an auxiliary power to rotate the wheel.

When a driver turns a steering wheel, the steering angle sensor detects the number of turns of the steering wheel to transmit the same to an electronic control unit (ECU), and the ECU controls the steering actuator, which can rotate the wheel, to generate steering output.

However, in the SBW system, fatal errors may be caused by a non-steerable state in which an electric signal is not provided due to a short circuit or a contact failure of a wire on a signal path through which steering is detected and transferred to an actuator, and thus a driver's steering intention is not correctly transferred to the wheel, or in which the steering actuator or the electronic control unit breaks down and malfunctions.

A backup clutch driving apparatus for a steer-by-wire is exemplified as an example of a safety apparatus for preventing such problems from arising.

FIG. 1illustrates a backup clutch driving apparatus for a steer-by-wire according to the related art.

As illustrated inFIG. 1, the backup clutch driving apparatus for a steer-by-wire according to the related art includes a first column shaft102, a second column shaft104, an electromagnetic coil106, an armature108, an output-side hub110, an armature hub112, and a plate spring114.

The armature hub112is secured to the first column shaft102connected to a steering wheel (not illustrated), and the plate spring114is connected to the armature hub112.

The armature108is attached to the plate spring114.

The output-side hub110is secured to the second column shaft104and surrounded by the electromagnetic coil106.

When the steer-by-wire is operating normally, the first and second column shafts102,104are mechanically separated from each other. Therefore, a driver's steering force which is transmitted to the first column shaft102is not mechanically transferred to the second column shaft104.

However, when an error occurs in the steer-by-wire, a current is applied to the electromagnetic coil106, thereby causing a magnetic field. The magnetic field attracts the armature108against the restoring force of the plate spring114so that the armature108is brought into contact with the output-side hub110.

When the armature108is brought into contact with the output-side hub110, the first and second column shafts102,104are mechanically connected to each other and the driver's steering force is transmitted to wheels, thereby solving a fatal error caused by malfunction of the steer-by-wire.

However, the backup clutch driving apparatus for a steer-by-wire according to the related art has a complex structure, and the electromagnetic coil employed for the backup clutch driving apparatus for a steer-by-wire has limitations due to its small driving force in cases where a large driving force is required and its high production cost is a drawback.

SUMMARY OF THE INVENTION

The present invention has been conceived to solve such problems in the related art, and an aspect of the present invention is to provide a safety apparatus for a steer-by-wire that can ensure the safety of a steer-by-wire using a simple and compact structure and can be manufactured at a low cost.

The aspect of the present invention is not limited thereto, and other unmentioned aspects of the present invention may be clearly appreciated by those skilled in the art from the following descriptions.

In accordance with one aspect of the present invention, a safety apparatus for a steer-by-wire includes: a first rotating plate formed on an end portion of any one of an input shaft and an output shaft that are separated from each other, wherein the first rotating plate has a through hole formed at a position spaced apart from the center thereof and is provided with a first position detecting sensor; a second rotating plate formed on an end portion of the other of the input shaft and the output shaft to face the first rotating plate, wherein the second rotating plate has an actuator coupled thereto and is provided with a second position detecting sensor interacting with the first position detecting sensor, and the actuator includes a load part that is inserted into or extracted from the through hole; and a controller that receives a signal for a relative rotation angle between the first and second rotating plates from the first and second position detecting sensors and controls the actuator to extract the load part from the through hole when the steer-by-wire is operating normally and to insert the load part into the through hole when the steer-by-wire malfunctions.

As described above, according to the embodiment, it is possible to ensure the safety of a steer-by-wire using a simple and compact structure and to achieve a manufacturing-cost reduction effect.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Hereinafter, some embodiments of the present invention will be described in detail with reference to the exemplary drawings. In the following description, It should be appreciated that when one component is described as being “connected,” “coupled” or “joined” to another component, a third component may be “connected,” “coupled,” and “joined” between the first and second components, although the first component may be directly connected, coupled or joined to the second component.

FIG. 2illustrates a structure of a steering apparatus having a safety apparatus for a steer-by-wire applied thereto according to an embodiment of the invention,FIG. 3is a fragmentary sectional view and a perspective view of a safety apparatus for a steer-by-wire according to an embodiment of the invention,FIG. 4is a fragmentary sectional view and a perspective view of a safety apparatus for a steer-by-wire according to another embodiment of the invention,FIGS. 5 and 6are fragmentary sectional views of a safety apparatus for a steer-by-wire according to embodiments of the invention, andFIG. 7is a fragmentary sectional view illustrating an operating state of a safety apparatus for a steer-by-wire according to an embodiment of the invention.

As illustrated in the drawings, a safety apparatus for a steer-by-wire according to an embodiment of the present invention includes: a first rotating plate215formed on an end portion of any one of an input shaft221and an output shaft201that are separated from each other, wherein the first rotating plate215has a through hole301formed at a position spaced apart from the center thereof and is provided with a first position detecting sensor303; a second rotating plate223formed on an end portion of the other of the input shaft221and the output shaft201to face the first rotating plate215, wherein the second rotating plate223has an actuator225coupled thereto and is provided with a second position detecting sensor307interacting with the first position detecting sensor303, and the actuator225includes a load part305that is inserted into or extracted from the through hole301; and a controller213that receives a signal for a relative rotation angle between the first and second rotating plates215,223from the first and second position detecting sensors303,307and controls the actuator225to extract the load part305from the through hole301when the steer-by-wire is operating normally and to insert the load part305into the through hole301when the steer-by-wire malfunctions.

Although it will be hereinafter exemplified that the first rotating plate215is formed on an end portion of the output shaft201and the second rotating plate223is formed on an end portion of the input shaft221, the reverse is possible.

A pinion gear203formed on the lower end portion of the output shaft201is engaged with a rack gear207formed on a rack bar205. A driving motor209is coupled to the rack bar205, and the rack bar205is linearly moved to the left and right by the driving force of the driving motor209to steer wheels211.

The driving motor209receives a control signal from the controller213and generates a driving force for moving the rack bar205leftwards and rightwards.

That is, the controller213receives signals from a first sensor229disposed on the input shaft221, a second sensor231disposed on the output shaft201, and other various types of sensors and controls the driving motor209to satisfy the moving distance of the rack bar205corresponding to the rotation angle of a steering wheel227.

The first rotating plate215is coupled to the upper end portion of the output shaft201and has the through hole301formed therein and the first position detecting sensor303.

Here, the through hole301may be formed at a position spaced apart from the center of the first rotating plate215, and the first position detecting sensor303may be disposed to be symmetric to the through hole301with respect to the center of the first rotating plate215.

Meanwhile, according to the embodiment of the present invention illustrated inFIG. 3, a plurality of through holes301and first position detecting sensors303may be formed along the circumferential direction of the first rotating plate215. Here, as illustrated inFIG. 4, a plurality of through holes401may be formed in such a manner that the adjacent ones overlap each other.

That is, as illustrated inFIG. 3, the plurality of through holes301may be adjacently formed to be spaced apart from each other in the circumferential direction of the first rotating plate215. Alternatively, as illustrated inFIG. 4, the plurality of through holes401may be formed in such a manner that the adjacent ones overlap each other, whereby wide sections A and narrow sections B may be alternately formed in the circumferential direction and the upper and lower surfaces of the first rotating plate215may be communicated with each other.

Particularly, in cases where the through holes401are formed in such a manner that the adjacent ones overlap each other as illustrated inFIG. 4, the rack gear207formed on the rack bar205may be formed as, for example, a variable gear. Accordingly, even though an interval exists where the rotation angles of the input and output shafts221,201are different from each other, the load part305of the actuator225can be effectively inserted into or extracted from the through holes401in cases where an error in the steer-by-wire arises, thereby sufficiently ensuring steering stability.

When the load part305of the actuator225is extracted from the though holes401due to an error in the steer-by-wire, a special case may occur in which the load part305is stopped by the narrow sections B of the through holes401. However, since a predetermined relative rotation angle interval (namely, an angle interval where the output shaft201does not rotate in conjunction with the input shaft221even though a driver turns the steering wheel227by a predetermined angle to rotate the input shaft221) exists between the input and output shafts221,201, a case does not occur where the load part305is stopped by the narrow sections B of the through holes401so that the safety apparatus for the steer-by-wire incompletely operates.

That is, even though the aforementioned special situation occurs, if the driver slightly rotates the steering wheel227without realizing it, the load part305departs from the narrow section B of the through holes401and then enters the wide section A thereof in the process in which the input shaft221connected to the steering wheel227is rotated. Therefore, the aforementioned incomplete operation of the safety apparatus for the steer-by-wire does not occur.

Meanwhile, referring toFIGS. 3 and 4, a plurality of first position detecting sensors403may be disposed to be spaced apart from each other in the circumferential direction in the first rotating plate215having the through holes401formed therein.

The input shaft221connected to the steering wheel227is rotated in conjunction with the steering wheel227when the driver turns the steering wheel227.

The second rotating plate223is coupled to the lower end portion of the input shaft221and is provided with the actuator225and the second position detecting sensor307.

The actuator225includes the load part305which is inserted into or extracted from the through holes301of the first rotating plate215. The through holes301have a slightly larger diameter than the load part305so that the load part305may be accurately inserted into the through holes301in case of emergency. The actuator225may be, for example, a solenoid valve.

The second position detecting sensor307is disposed in the second rotating plate223to interact with the first position detecting sensor303disposed in the first rotating plate215. The first and second position detecting sensors303,307may be, for example, a magnet sensor and are disposed to face each other when the safety apparatus for the steer-by-wire, according to the embodiment of the present invention, is mounted to a vehicle.

As illustrated inFIGS. 3 and 4, in cases where the plurality of first position detecting sensors403are provided, a plurality of second position detecting sensors407are also provided on the second rotating plate223to correspond to the first position detecting sensors403.

Furthermore, as illustrated inFIG. 5, the load part305may have, on an end portion thereof, a diameter reducing portion305awhich has a gradually decreasing outer diameter, or as illustrated inFIG. 6, the through holes301may have, on an end portion thereof, a diameter expanding portion301awhich has a gradually increasing inner diameter and where the load part305is inserted. Alternatively, the load part305may have the diameter reducing portion305aand, at the same time, the through holes301may have the diameter expanding portion301a.

In this way, the load part305has the diameter reducing portions305a, and/or the through holes301have the diameter expanding portion301a. Accordingly, when the first and second rotating plates215,223are not situated at the correct positions, even though the driver slightly turns the steering wheel227, the load part305of the actuator may be easily inserted into the through holes301.

When the safety apparatus for the steer-by-wire, according to the embodiment of the present invention, is mounted to a vehicle, the first and second position detecting sensors303,307are set to face each other, and the controller213may determine that the first and second rotating plates215,223are initially disposed at the correct positions where the load part305of the actuator225may be inserted into the through hole301.

When the first and second rotating plates215,223depart from a preset relative rotation angle range, the controller213may also identify the state.

The controller213receives a signal for a relative rotation angle between the first and second rotating plates215,223from the first and second position detecting sensors303,307and controls the actuator225to extract the load part305from the through hole301when the steer-by-wire is operating normally (seeFIG. 7 (a)) and to insert the load part305into the through hole301when the steer-by-wire malfunctions (seeFIG. 7(b)).

That is, only when the steer-by-wire malfunctions, the controller213controls the actuator225to insert the load part305of the actuator225into the through hole301so that the input and output shafts221,201are physically connected to each other, thereby making it possible for a driver to manually steer the wheels211in case of emergency (e.g., a case where a vibration of 0.13 g or more is consistently generated in the steering wheel for 20 ms or more).

The controller213determines whether the steer-by-wire is operating normally based on signals transmitted from the first and second sensors229,231for detecting the rotation angles of the input and output shafts221,201, respectively, and signals transmitted from other various sensors.

Meanwhile, a first gear233is mounted on the input shaft221and engaged with a second gear237connected to the shaft of a motor235, and the controller213controls the motor235to give a driver a feeling of general steering while driving a vehicle.

As described above, according to the embodiment, it is possible to ensure the safety of a steer-by-wire using a simple and compact structure and to achieve a manufacturing-cost reduction effect.

Even if it was described above that all of the components of an embodiment of the present invention are coupled as a single unit or coupled to be operated as a single unit, the present invention is not necessarily limited to such an embodiment. The scope of the present invention shall be construed on the basis of the accompanying claims in such a manner that all of the technical ideas included within the scope equivalent to the claims belong to the present invention.