STEER BY WIRE DEVICE OF A VEHICLE

Abstract

According to the present invention, in a steer-by-wire apparatus for a vehicle, there is provided a rack shaft on which a rack gear is installed and which adjusts the steering angle of a vehicle wheel by the linear motion of the rack gear; a pinion gear meshed with the rack gear and linearly moving the rack gear by a rotational motion; a first sun gear and a second sun gear installed to face each other, at least one planetary gear meshed with the first sun gear and the second sun gear and revolving about a revolution axis connecting the center point of the first sun gear and the center point of the second sun gear corresponding to the rotational motion of at least one of the first sun gear and the second sun gear, and a differential gear module including a case coupled to the planetary gear and rotating about the revolution axis and coupled to the pinion gear; a first actuator and a second actuator for rotating the first sun gear and the second sun gear, respectively; at least one controller for controlling the first actuator and the second actuator in response to steering input information; and a steering sensor for sensing at least part of the momentum of the rack gear and the pinion gear; A steer-by-wire apparatus is disclosed.

Description

Technical Field

[0001] The present invention relates to a steer-by-wire device for a vehicle, and more particularly, to a steer-by-wire device for a vehicle that can provide redundancy to cope with not only electrical failures but also mechanical failures of an actuator for driving a wheel steering mechanism of the steer-by-wire device for a vehicle.

Background Art

[0002] A steer-by-wire system is a steering system that transmits and controls an operation on a driver's steering wheel to a wheel steering mechanism by an electrical signal in a state where the mechanical connection between the steering wheel of a vehicle and the wheel steering mechanism is completely eliminated.

[0003] In a steer-by-wire system, since the mechanical connection between the steering wheel of a vehicle and the wheel steering mechanism is completely eliminated and controlled by an electrical signal, an operation on the driver's steering wheel can be directly reflected on the wheel steering mechanism, unnecessary vibrations are blocked, the steering gear ratio can be freely changed, and an unintended steering input during autonomous driving can be basically blocked.

[0004] Referring to FIG. 1, the structure of a conventional steer-by-wire device 1000 according to the prior art is as follows.

[0005] Referring to FIG. 1, a conventional steer-by-wire device 1000 according to the prior art can include a steering input mechanism 1100 that receives an input on a steering wheel (not shown) by a user as steering input information. The steering input mechanism 1100 can include a steering wheel sensor that senses the momentum of the steering wheel.

[0006] And the conventional steer-by-wire device 1000 can include a wheel steering mechanism 1200 for steering the wheels of a vehicle. Here, the wheel steering mechanism 1200 can include a rack shaft 1210 that adjusts the steering angle of the vehicle's wheels according to position, and a steering sensor 1270 that senses the position of the rack shaft 1210. Further, the wheel steering mechanism 1200 can include a controller (not shown) that controls the wheel steering mechanism 1200 with reference to the steering input information of the steering input mechanism 1100.

[0007] At this time, the steering input information of the steering input mechanism 110 can be transmitted to the controller of the wheel steering mechanism 1200 using CAN (Controller Area Network) communication.

[0008] However, since there is no mechanical connection between the steering wheel of the vehicle and the steering mechanism of the wheels in the steer-by-wire system, when an electrical failure occurs in the system itself, there is a major safety problem that the driver cannot perform any steering control even when operating the steering wheel.

[0009] To prevent this, in the existing technology, through electronic control duplication, even if a failure occurs in the first electronic control controller, the steering control can be maintained using the second electronic control controller.

[0010] However, in the case of such a steer-by-wire system, when a mechanical failure occurs in the actuator of the wheel steering mechanism itself, the steering control becomes impossible, which is a problem that may lead to a major accident.

[0011] Therefore, it is necessary to develop a steer-by-wire system that can perform steering control through redundancy even when a mechanical failure occurs in the actuator of the wheel steering mechanism itself. Summary of the Invention Problems to be Solved by the Invention

[0012] The object of the present invention is to solve all of the above-described problems.

[0013] Another object of the present invention is to provide a steer-by-wire device capable of performing steering control even when a failure occurs in an actuator of a steering mechanism of a wheel.

[0014] Another object of the present invention is to provide redundancy not only for an electrical failure but also for a mechanical failure of an actuator of a steering mechanism of a wheel.

[0015] Another object of the present invention is to provide redundancy for a steer-by-wire device that rotates a sun gear not driven by the rotation of a planetary gear of the present invention.

[0016] Another object of the present invention is to enable redundancy due to a failure of an actuator of the steer-by-wire device of the present invention to be realized while minimizing spatial constraints.

Means for Solving the Problems

[0017] According to an embodiment of the present invention, in a steer by wire device of a vehicle, there is a rack gear installed, and a rack shaft that adjusts the steering angle of the vehicle wheel by the linear motion of the rack gear; a pinion gear meshed with the rack gear that linearly moves the rack gear by rotational motion; a first sun gear and a second sun gear installed to face each other, at least one planet gear meshed with the first sun gear and the second sun gear that revolves around a revolution axis connecting the center point of the first sun gear and the center point of the second sun gear corresponding to the rotational motion of at least one of the first sun gear and the second sun gear, and a differential gear module including a case coupled to the planet gear that rotates around the revolution axis and is coupled to the pinion gear; a first actuator and a second actuator that respectively rotate the first sun gear and the second sun gear; at least one controller that controls the first actuator and the second actuator corresponding to steering input information; and a steering sensor that senses at least part of the momentum of the rack gear and the pinion gear; a steer by wire device is provided.

[0018] In one example, the controller refers to the driving state information of the vehicle to judge the rack load condition during steering of the vehicle. When the rack load condition exceeds a predetermined first load value, the first actuator and the second actuator are controlled so that the steering angle of the vehicle wheel is adjusted. When the rack load condition is equal to or less than a predetermined second load value (the predetermined second load value is smaller than the predetermined first load value), one specific actuator of the first actuator and the second actuator is controlled so that the steering angle of the vehicle wheel is adjusted.

[0019] In one example, the controller controls the specific actuator such that the steering angle of the vehicle wheel is adjusted when the rack load condition is equal to or less than the predetermined second load value, and when at least a part of the momentum of the rack gear and the pinion gear sensed from the steering sensor is smaller than the allowable threshold value by more than the target momentum corresponding to the steering input information, it is determined that the specific actuator has failed, and another actuator is controlled so that the steering angle of the vehicle wheel is adjusted.

[0020] In one example, when a specific controller among the controllers controls the first actuator and the second actuator, and another controller other than the specific controller (the other controller can control the first actuator and the second actuator) cannot receive the operation state information from the specific controller for a certain period of time, it is determined that the specific controller has failed, and the first actuator and the second actuator are controlled instead of the specific controller so that the steering angle of the vehicle wheel is adjusted.

[0021] In one example, each of the first actuator and the second actuator includes a first lock unit and a second lock unit that lock and unlock the rotation of the first sun gear and the second sun gear, respectively.

[0022] In one example, the first actuator includes a first motor that generates power, a first speed reducer that converts the power generated from the first motor to correspond to the first power value, and a first sun gear shaft that connects the first speed reducer and the first sun gear, and the second actuator includes a second motor that generates power, a second speed reducer that converts the power generated from the second motor to correspond to the second power value, and a second sun gear shaft that connects the second speed reducer and the second sun gear.

[0023] In one example, the first motor includes a first_1 winding to a first_n winding (where n is an integer of 2 or more) that generates the power of the first motor, the second motor includes a second_1 winding to a second_n winding that generates the power of the second motor, the controller includes a first controller to an nth controller, and when the first_1 winding and the second_1 winding are a first winding pair, each of the first winding pair to the nth winding pair is connected to and controlled by each of the first controller to the nth controller.

[0024] In one example, the first motor includes one first winding that generates the power of the first motor, the second motor includes one second winding that generates the power of the second motor, the controller includes a specific controller and other controllers, and when the first winding and the second winding are respectively connected to the specific controller and the other controllers, and when the specific controller in the controller controls the first winding and the second winding, if other controllers other than the specific controller (the other controllers can control the first winding and the second winding) cannot receive the operation state information from the specific controller for a certain period of time, it is determined that the specific controller has failed, and the first winding and the second winding are respectively used to generate the power of the first motor and the second motor.

Advantages of the Invention

[0025] According to the present invention, the following effects are achieved.

[0026] According to the present invention, since steering control is possible even if a failure occurs in the actuator of the wheel steering mechanism in the steer-by-wire device, the running stability of the vehicle can be improved.

[0027] The present invention can rotate the sun gear that is not driven by the rotation of the planetary gear of the steer-by-wire device.

[0028] The present invention can easily implement redundancy due to a failure of an actuator of a steer-by-wire device without spatial constraints.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0030] The detailed description of the present invention, which will be described later, refers to the accompanying drawings that illustrate, by way of example, specific embodiments in which the present invention can be implemented. These embodiments are described in detail so that those skilled in the art can fully implement the present invention. It should be understood that the various embodiments of the present invention are different from each other but do not have to be mutually exclusive. For example, the specific shapes, structures, and characteristics described herein can be embodied in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. Also, it should be understood that the position or arrangement of the individual components within each disclosed embodiment can be changed without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention is limited only by the appended claims, together with all ranges equivalent to what the claims claim, as appropriately explained. In the drawings, like reference numerals refer to the same or similar components throughout the various aspects.

[0031] Hereinafter, in order to enable those having ordinary knowledge in the technical field to which the present invention pertains to easily implement the present invention, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0032] First, a steer-by-wire device for a vehicle according to the present invention will be described with reference to FIGS. 2 and 3.

[0033] FIG. 2 schematically shows a part of a steer-by-wire device according to an embodiment of the present invention, FIG. 3 schematically shows a cross-sectional view of a part of a steer-by-wire device according to an embodiment of the present invention.

[0034] Referring to FIGS. 2 and 3, a steer-by-wire device for a vehicle according to the present invention can include a rack shaft on which a rack gear 2220 is installed, and the steering angle of the vehicle wheels is adjusted by the linear motion of the rack gear 2220. Here, the rack shaft can also adjust the steering angle of the vehicle wheels by its own linear motion.

[0035] The rack gear 2220 may be meshed with a pinion gear 2230 that linearly moves the rack gear 2220 by rotational motion.

[0036] Here, the pinion gear 2230 has a cylindrical form and may be meshed with the rack gear 2220 at a certain point around it. At this time, the pinion gear 2230 can rotate in both clockwise and counterclockwise directions at its original position, and the moving direction of the rack gear 2220 may be reversed depending on the rotation direction of the pinion gear 2230.

[0037] Also, the steer-by-wire device for a vehicle according to the present invention can include a differential gear module 2240.

[0038] As an example, the differential gear module 2240 can include a first sun gear 2241 and a second sun gear 2242 installed to face each other.

[0039] And between the first sun gear 2241 and the second sun gear 2242, a planetary gear 2243 that is simultaneously meshed with the first sun gear 2241 and the second sun gear 2242 can be included.

[0040] At this time, the planetary gear 2243 can revolve around the revolution axis connecting the center points of the first sun gear 2241 and the second sun gear 2242 corresponding to the rotational movement of at least one of the first sun gear 2241 and the second sun gear 2242. Further, the planetary gear 2243 can rotate due to the difference in driving force between the first sun gear 2241 and the second sun gear 2242. That is, when either one of the first sun gear 2241 and the second sun gear 2242 is not driven, the planetary gear 2243 can be rotated by the driving on the driven sun gear side, and the non-driven sun gear can be rotated by the rotation of the planetary gear 2243. Also, the planetary gear 2243 can revolve around the revolution axis by the driving force of the driven sun gear. And the number of the planetary gears 2243 is not limited, and a plurality of them can exist satisfying the condition of being simultaneously meshed with the first sun gear 2241 and the second sun gear 2242.

[0041] And the differential gear module 2240 can include a case 2244 coupled to the pinion gear 2230 and rotating around the revolution axis around which the planetary gear 2243 revolves.

[0042] At this time, the case 2244 may be in a cylindrical form and wrap the first sun gear 2241, the second sun gear 2242, and the planetary gear 2243, but is not limited to such a form, and can rotate at the original position around the same axis as the revolution axis around which the planetary gear 2243 revolves.

[0043] On the other hand, although an example of the differential gear module 2240 has been described above, the present invention is not limited thereto, and the differential gear module 2240 can also be configured in various ways so that the planetary gear is revolved by the driving force of the sun gear.

[0044] Also, the steer-by-wire device for a vehicle according to the present invention can include a first actuator 2250 and a second actuator 2260 that respectively rotate the first sun gear 2241 and the second sun gear 2242.

[0045] Here, the first actuator 2250 and the second actuator 2260 are configured such that power is supplied through different routes, and even if the power supply to one of the actuators is stopped, the other actuator can be supplied with power.

[0046] On the other hand, the first actuator 2250 and the second actuator 2260 can be installed parallel to the linear motion direction of the rack gear 2220 in order to minimize the installation space, and the rotational power of the first actuator 2250 and the second actuator 2260 can be converted and transmitted in the shaft direction of the first sun gear 2241 and the second sun gear 2242 through their respective bevel gears. Thus, the present invention does not separately configure the driving force transmission of the first actuator 2250 and the second actuator 2260 for driving the rack - pinion for controlling the steering of the vehicle wheel, but enables the rack - pinion to be driven by the first actuator 2250 and the second actuator 2260 through a single differential gear module 2240, so that redundancy due to actuator failure can be easily implemented without spatial constraints. At this time, each bevel gear can act as a speed reducer for adjusting the rotational power transmitted from the first actuator 2250 to the first sun gear 2241 and the rotational power transmitted from the second actuator 2260 to the second sun gear 2242. However, what acts as a speed reducer for adjusting the rotational power in the present invention is not limited to the bevel gear, and speed reducers of various shapes can be used depending on the installation directions of the first actuator 2250 and the second actuator 2260.

[0047] Also, the first sun gear shaft for transmitting the driving force from the first actuator 2250 to the first sun gear can be coupled to the sun gear through the hollow formed in the pinion gear 2230.

[0048] In addition, the steer-by-wire apparatus for a vehicle according to the present invention can include at least one controller that controls a first actuator 2250 and a second actuator 2260 in response to steering input information for automatically performing vehicle steering based on steering input information by a driver's steering wheel operation or vehicle running information. At this time, the number of controllers and the control relationship can be implemented in various forms, which will be described later.

[0049] Furthermore, the steer-by-wire apparatus for a vehicle according to the present invention can include a steering sensor that senses at least part of the momentum of a rack gear 2220 and a pinion gear 2230. At this time, the steering sensor can sense the linear momentum of the rack gear 2220 and the rotational momentum of the pinion gear 2230 and the like.

[0050] In the steer-by-wire apparatus for a vehicle according to the present invention configured as described above, the first sun gear 2241 and the second sun gear 2242 are caused to rotate by the driving forces of the first actuator 2250 and the second actuator 2260, whereby the planetary gear 2243 is caused to rotate. Then, the case 2244 is caused to rotate in conjunction with the rotation of the planetary gear 2243, and the steering angle of the vehicle wheel can be controlled by the linear movement of the rack gear 1220 due to the rotational movement of the pinion gear 2230 linked thereto.

[0051] Next, a form in which a lock unit is used in the steer-by-wire apparatus according to the present invention will be described with reference to FIG. 4.

[0052] According to an embodiment of the present invention as described above, the sun gear that is not driven by the rotation of the planetary gear 2243 can be rotated. However, when the rotational speed of the driven sun gear is high, for example, when a speed reducer with a low reduction ratio is applied, the driving force of the normally driven sun gear may be dispersed to the actuator that is not driven through the non-driven sun gear. To prevent this, each of the first actuator 2250 and the second actuator 2260 can be embodied to include respective first locking units 2310 and second locking units 2320 that lock or unlock the rotation of the first sun gear 2241 and the second sun gear 2242. At this time, the first locking unit 2310 and the second locking unit 2320 can be installed at any position on the driving force transmission path from each sun gear to each actuator, and can be embodied in various structures that can lock the driving force transmission, that is, the rotational movement on the driving force transmission path. As an example, it can be configured in various forms such as directly providing frictional force to the driving force transmission shaft to prevent the rotation of the driving force transmission shaft, or meshing with any gear device on the driving force transmission path to prevent the rotation of the gear.

[0053] FIG. 4 schematically shows a form in which the first locking unit 2310 and the second locking unit 2320 are installed in a steer-by-wire device according to an embodiment of the present invention.

[0054] Referring to FIG. 4, in the present invention, each of the first actuator 2250 and the second actuator 2260 can include respective first locking units 2310 and second locking units 2320.

[0055] At this time, the first lock unit 2310 and the second lock unit 2320 can each be composed of a solenoid valve, and each solenoid valve can be installed in the speed reducer of each of the first actuator 2250 and the second actuator 2260. However, the present invention is not limited thereto, and various devices that block the rotational force on the driving force transmission path other than the solenoid valve can be used as the lock unit, and it can be installed not only in the speed reducer but also at various positions on the driving force transmission path.

[0056] The solenoid valve blocks the rotation of the speed reducer gear in the locked state and maintains the state where the driving force transmission by the speed reducer is blocked. Then, in response to the actuator drive signal, the solenoid valve is driven to an unlocked state, thereby enabling the release of the driving force transmission blocking by the speed reducer by the actuator drive signal.

[0057] Through this, when there is a failed actuator, since the actuator drive signal is not applied to the failed actuator due to redundancy, the solenoid valve maintains the locked state, preventing the driving force of the normally driven actuator from being dispersed to the side of the failed actuator. Also, when there is a selectively deactivated actuator, the speed reducer on the side of the deactivated actuator can have its driving force transmission blocked by the locked state of the solenoid valve.

[0058] Here, when the first lock unit 2310 is locked, the first lock pin 2311 protrudes outside the first lock body 2312, and when unlocked, the first lock pin 2311 is retracted inside the first lock body 2312. At this time, the first lock pin 2311 in the locked state can be engaged with a speed reducer (which may be a bevel gear, for example) to prevent the rotation of the speed reducer. Similarly, when the second lock unit 2320 is locked, the second lock pin 2321 protrudes outside the second lock body 2322, and when unlocked, the second lock pin 2321 is retracted inside the second lock body 2322. At this time, the second lock pin 2321 in the locked state can be engaged with a speed reducer (which may be a bevel gear, for example) to prevent the rotation of the speed reducer.

[0059] Next, with reference to FIG. 5, the process by which the controller controls the first actuator 2250 and the second actuator 2260 according to the rack load will be described.

[0060] FIG. 5 is a flowchart briefly showing the process by which the controller controls the first actuator 2250 and the second actuator 2260 according to the rack load in the steer-by-wire device according to an embodiment of the present invention.

[0061] According to FIG. 5, in the steer-by-wire device of the vehicle according to the present invention, the controller can determine the rack load condition during vehicle steering with reference to the driving state information of the vehicle (S401). That is, when the vehicle is in a driving state, since the load required during steering is small, the rack load condition is determined to be equal to or less than a predetermined second load value. When the vehicle is in a stopped state, since the load required during steering is large, the rack load condition can be determined to exceed a predetermined first load value. Here, the predetermined second load value is smaller than the predetermined first load value.

[0062] When the vehicle is in a stopped state and the rack load condition exceeds a predetermined first load value, the controller can control (S402) so that all of the first actuator 2250 and the second actuator 2260 are activated. In this case, power is supplied to both the first sun gear 2241 and the second sun gear 2242 to rotate the pinion gear 2230, whereby the steering angle of the vehicle wheel can be adjusted.

[0063] Conversely, when the vehicle is in a running state and the rack load condition is equal to or less than a predetermined second load value, any one of the first actuator 2250 and the second actuator 2260 can be controlled to adjust the steering angle of the vehicle wheel (S403). That is, power can be supplied to only one of the first sun gear 2241 and the second sun gear 2242 to rotate the pinion gear 2230.

[0064] At this time, if a failure occurs in a specific actuator, the pinion gear 2230 will not rotate at all, so that the vehicle may not be steered and an accident may occur. Therefore, the controller senses at least part of the momentum of the rack gear 2220 and the pinion gear 2230 from the steering sensor 2270, and when the sensed momentum is smaller than the allowable threshold value compared to the target momentum corresponding to the steering input information, it can be determined that a specific actuator has failed (S404). That is, when the driver inputs to the steering wheel, if the actual steering of the vehicle is significantly smaller than the steering input information input by the steering wheel, another actuator (for example, when the first actuator 2250 is controlled but not steered, it is the second actuator 2260) can be controlled (S405). Thereby, the steering angle of the vehicle wheel can be adjusted.

[0065] Here, when the controller controls the first actuator 2250 among the first actuator 2250 and the second actuator 2260 to supply power, the first lock unit 2310 is in an unlocked state, and the second lock unit 2320 is in a locked state, and the driving force of the first actuator 2250 can be configured to prevent transmission to the second actuator 2260.

[0066] In the example of FIG. 4, each of the first lock pin 2311 and the second lock pin 2321 of the first lock unit 2310 and the second lock unit 2320 is in a state located at the bevel gear of each of the first actuator 2250 and the second actuator 2260. According to the example of FIG. 4, when power is supplied from the second actuator 2260 and no power is supplied from the first actuator 2250, the first lock unit 2310 located on the first actuator 2250 side maintains the locked state to prevent the first lock pin 2311 from rotating the bevel gear. Therefore, even when power is supplied from the second actuator 2260, the motor, bevel gear, and first sun gear 2241 on the first actuator 2250 side do not rotate, and power loss can be reduced. In the example of FIG. 4, the first lock unit 2310 and the second lock unit 2320 are connected to each of the bevel gears. However, the installation positions of the first lock unit 2310 and the second lock unit 2320 may be any positions of the first actuator 2250 and the second actuator 2260, respectively. For example, the first lock unit 2310 can be installed on the motor of the first actuator 2310, and the second lock unit 2320 can be installed on the speed reducer of the second actuator 2260, but it is not limited thereto.

[0067] For example, when the controller supplies power to the first actuator 2250 and does not supply power to the second actuator 2260, the first lock unit 2310 of the first actuator 2250 is switched to the unlocked state, and the first lock pin 2311 is retracted into the first lock body 2312 so that the first actuator 2250 can rotate. At the same time, the second lock unit 2320 of the second actuator 2260 can be configured to maintain the locked state so that the power of the first actuator 2250 is not transmitted to the second actuator 2260. Of course, conversely, when power is supplied to the second actuator 2260, the second lock unit 2320 of the second actuator 2260 is switched to the unlocked state, and the second lock pin 2321 is retracted into the second lock body 2322 so that the second actuator 2260 can rotate. At the same time, the first lock unit 2310 of the first actuator 2250 can be configured to maintain the locked state so that the power of the second actuator 2260 is not transmitted to the first actuator 2250.

[0068] On the other hand, in the above, it is determined whether the load condition exceeds a predetermined first load value or is equal to or less than a predetermined second load value by referring to the vehicle operation information. In contrast, various load conditions according to respective operation conditions can be set by using the vehicle operation information, that is, speed, target wheel angle, etc., and the operation of the actuator and the torque at each actuator can be controlled according to each load condition. Further, the actual vehicle load can be detected through a load sensor, the rack load can be calculated based on the detected vehicle load, and the actuator can be controlled based on the calculated rack load.

[0069] Next, with reference to FIG. 6, in the steer-by-wire device according to the present invention, the process in which another controller controls the first actuator 2250 and the second actuator 2260 depending on the presence or absence of a failure of a specific controller will be described.

[0070] FIG. 6 is a flowchart that briefly shows the process in which, in a steer-by-wire device according to an embodiment of the present invention, another controller controls a first actuator 2250 and a second actuator 2260 depending on whether a specific controller has failed.

[0071] The steer-by-wire device for a vehicle according to the present invention can include a number of controllers. Referring to FIG. 6, among the controllers, a specific controller can be configured to control both the first actuator 2250 and the second actuator 2260 (S501). Other controllers other than the specific controller can also be configured to control both the first actuator 2250 and the second actuator 2260.

[0072] Here, the specific controller and other controllers can be configured to transmit and receive operation state information regarding each other in order to determine a failure. When another controller cannot receive the operation state information from the specific controller for a certain period of time, the other controller can determine that the specific controller has failed (S502). Thereafter, the other controller can control the first actuator 2250 and the second actuator 2260 in place of the specific controller, and the steering angle of the vehicle wheel can be adjusted (S503).

[0073] The number of controllers is not limited. For example, when there are a first controller, a second controller, and a third controller, it can be configured to transmit and receive operation state information among all of them, between the first controller and the second controller, between the first controller and the third controller, and between the second controller and the third controller.

[0074] In the steer-by-wire system of a vehicle according to the present invention, the first actuator 2250 can include a first motor that generates power, a first speed reducer that converts the power generated from the first motor so as to correspond to a first power value, and a first sun gear shaft that connects the first speed reducer and the first sun gear 2241. The first speed reducer can be configured such that when transmitting the power of the first motor to the first sun gear shaft, the power can be adjusted at a constant ratio.

[0075] Similarly, the second actuator 2260 can include a second motor that generates power, a second speed reducer that converts the power generated from the second motor so as to correspond to a second power value, and a second sun gear shaft that connects the second speed reducer and the second sun gear 2242. Similarly, the second speed reducer can be configured such that when transmitting the power of the second motor to the second sun gear shaft, the power can be adjusted at a constant ratio.

[0076] In one embodiment of the present invention, the first motor can include a first_1 winding to a first_n winding that generates the power of the first motor. Here, n can be an integer of 2 or more.

[0077] The second motor can include a second_1 winding to a second_n winding that generates the power of the second motor. That is, the number of windings of the second motor can be configured to be the same as that of the first motor.

[0078] At this time, the controller includes the first controller to the nth controller. When the first winding 1_1 and the second winding 2_1 form the first winding pair, each of the first winding pair to the nth winding pair can be connected to and controlled by each of the first controller to the nth controller. In other words, each of the windings of the first motor and each of the windings of the second motor form pairs one by one, and a pair of windings can be controlled by one controller. Therefore, one controller can control one winding of the first motor and one winding of the second motor. Through such a configuration, even if a mechanical failure occurs in some of the motor windings, there is an advantage that the vehicle can be steered by controlling other windings.

[0079] In another embodiment of the present invention, the first motor can include one first winding that generates the power of the first motor.

[0080] Similarly, the second motor can include one second winding that generates the power of the second motor, and the controller can include a specific controller and other controllers.

[0081] At this time, the first winding and the second winding can be in a state of being respectively connected to a specific controller and other controllers. That is, the first winding and the second winding can be all controlled at once by a specific controller, and can also be all controlled at once by other controllers.

[0082] Here, the specific controller and other controllers can be configured to transmit and receive operation state information with respect to each other to determine a failure. At this time, the number of controllers is not limited. For example, when there are a first controller, a second controller, and a third controller, it can be configured to transmit and receive operation state information among all between the first controller and the second controller, between the first controller and the third controller, and between the second controller and the third controller.

[0083] Among the controllers, when a specific controller controls the first winding and the second winding, if other controllers cannot receive the operating state information from the specific controller for a certain period of time, it can be determined that the specific controller has failed. Thereafter, another controller can be controlled to replace the specific controller to generate the power of the first motor and the second motor.

[0084] As described above, the present invention has been described by way of specific examples and drawings limited to specific matters such as specific components. However, this is only provided to assist in a more general understanding of the present invention, and the present invention is not limited to the above examples. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and deformations from such descriptions.

[0085] Therefore, the idea of the present invention should not be defined as being limited to the described embodiments, and not only the scope of the following claims, but also all those equivalently or equivalently deformed from this scope of claims belong to the scope of the idea of the present invention.

Claims

1. In a steer-by-wire device for a vehicle, a rack shaft on which a rack gear is installed and which adjusts the steering angle of a vehicle wheel by the linear motion of the rack gear; a pinion gear meshed with the rack gear and linearly moving the rack gear by rotational motion; a differential gear module including a first sun gear and a second sun gear installed to face each other, at least one planet gear meshed with the first sun gear and the second sun gear and revolving around a revolution axis connecting the center point of the first sun gear and the center point of the second sun gear corresponding to the rotational motion of at least one of the first sun gear and the second sun gear, and a case coupled to the planet gear and rotating around the revolution axis and coupled to the pinion gear; a first actuator and a second actuator for rotating the first sun gear and the second sun gear, respectively; at least one controller for controlling the first actuator and the second actuator corresponding to steering input information; and a steering sensor for sensing at least part of the momentum of the rack gear and the pinion gear; A steer-by-wire device comprising the above.

2. The controller refers to the driving state information of the vehicle to judge the rack load condition during steering of the vehicle. When the rack load condition exceeds a predetermined first load value, the first actuator and the second actuator are controlled so that the steering angle of the vehicle wheel is adjusted. When the rack load condition is equal to or less than a predetermined second load value (the predetermined second load value is smaller than the predetermined first load value), any one specific actuator of the first actuator and the second actuator is controlled so that the steering angle of the vehicle wheel is adjusted. The steer-by-wire device according to Claim 1.

3. The controller is in a state where, when the rack load condition is equal to or less than the predetermined second load value, the specific actuator is controlled so that the steering angle of the vehicle wheel is adjusted. When at least a part of the momentum of the rack gear and the pinion gear sensed from the steering sensor is smaller than the allowable threshold value compared to the target momentum corresponding to the steering input information, it is determined that the specific actuator has failed, and other actuators are controlled so that the steering angle of the vehicle wheel is adjusted. The steer-by-wire device according to claim 2.

4. In a state where a specific controller in the controller controls the first actuator and the second actuator, When other controllers other than the specific controller (the other controllers can control the first actuator and the second actuator) cannot receive the operation state information from the specific controller for a certain period of time, it is determined that the specific controller has failed, and the first actuator and the second actuator are controlled in place of the specific controller so that the steering angle of the vehicle wheel is adjusted. The steer-by-wire device according to claim 1.

5. Each of the first actuator and the second actuator includes a first locking unit and a second locking unit that lock and unlock the rotations of the first sun gear and the second sun gear respectively. The steer-by-wire device according to claim 1.

6. The first actuator includes a first motor that generates power, a first speed reducer that converts the power generated from the first motor to correspond to the first power value, and a first sun gear shaft that connects the first speed reducer and the first sun gear. The second actuator includes a second motor that generates power, a second speed reducer that converts the power generated from the second motor to correspond to the second power value, and a second sun gear shaft that connects the second speed reducer and the second sun gear. The steer-by-wire device according to claim 1.

7. The first motor includes a first_1 winding to a first_n winding (where n is an integer of 2 or more) that generates the power of the first motor. The second motor includes a second_1 winding to a second_n winding that generates the power of the second motor. The controller includes a first controller to an nth controller. When the first winding 1_1 and the second winding 2_1 form a first winding pair, each of the first winding pair to the nth winding pair is connected to and controlled by each of the first controller to the nth controller, the steer-by-wire device according to claim 6.

8. The first motor includes a first winding that generates the power of the first motor. The second motor includes a second winding that generates the power of the second motor. The controller includes a specific controller and other controllers. In a state where the first winding and the second winding are respectively connected to the specific controller and the other controllers. When the specific controller in the controller controls the first winding and the second winding, if other controllers other than the specific controller (the other controllers can control the first winding and the second winding) cannot receive the operation state information from the specific controller for a certain period of time, it is determined that the specific controller has failed, and each of the first winding and the second winding is used to generate the power of each of the first motor and the second motor respectively, the steer-by-wire device according to claim 6.

Images