Steering apparatus for vehicle

Abstract

An automobile steering device is provided, comprising: a ball nut that rotates and moves the rack bar in the axial direction by being coupled to the rack bar via a ball; a nut pulley provided on the outer surface of the ball nut; a first motor pulley provided on a first motor and coupled to the nut pulley by a belt; a second motor pulley provided on a second motor and coupled to the belt between the nut pulley and the first motor pulley; and an electronic control unit that controls an output value transmitted to the first motor and the second motor using an electrical signal as an input value.

Description

Technology Field

[0001] These embodiments relate to an automobile steering system. Background Technology

[0002] Generally, power steering systems have been developed and applied to automotive steering devices to assist the driver's steering wheel operation and provide convenience in driving. Power steering systems have been developed and applied in various forms, including hydraulic types utilizing hydraulic pressure, electro-hydraulic types utilizing both hydraulic pressure and motor power, and electric types utilizing only motor power.

[0003] Recently, a Steer By Wire (SBW) steering system has been developed and applied, which enables steering of the vehicle using an electric motor instead of removing mechanical connecting devices such as a steering shaft, universal joint, or pinion shaft between the steering wheel and the road wheel.

[0004] However, in the case of such steer-by-wire steering systems, there was a problem in that the driver's steering intent could not be transmitted to the rack bar in the event of a motor failure because there was no mechanical connection between the steering shaft and the road wheel, and there was a problem in that the rack bar could rotate due to the rotational torque of the ball nut, which reduced steering stability.

[0005] In addition, given the absence of mechanical connections, countermeasures for failures and control technology capable of precisely controlling the motors located on the steering wheel and road wheels, respectively, are required.

[0006] Therefore, there is a growing need for technology that enables the driver's steering intent to be stably transmitted to the rack bar and to stably perform steering operations in both steer-by-wire steering systems and conventional steering systems. The problem to be solved

[0007] The present embodiments aim to provide a stable and effective automotive steering system. means of solving the problem

[0008] According to the embodiments, an automobile steering device may be provided comprising: a ball nut coupled to a rack bar via a ball and rotating to move the rack bar in the axial direction; a nut pulley provided on the outer surface of the ball nut; a first motor pulley provided on a first motor and coupled to the nut pulley by a belt; a second motor pulley provided on a second motor and coupled to the belt between the nut pulley and the first motor pulley; and an electronic control device that controls an output value transmitted to the first motor and the second motor using an electrical signal as an input value.

[0009] In addition, according to the embodiments thereof, an automobile steering device may be provided comprising: a ball nut coupled to a rack bar and a ball and rotating to move the rack bar in the axial direction; a nut pulley provided on the outer surface of the ball nut; a first motor pulley provided on a first motor and connected to the nut pulley by a belt; a second motor pulley provided on a second motor and coupled to a belt between the nut pulley and the first motor pulley; an electronic control device that controls an output value transmitted to the first motor and the second motor using an electrical signal as an input value; and a pinion shaft, one end of which is coupled to a steering shaft coupled to a steering wheel and the other end of which supports and is coupled to one end of the rack bar. Effects of the invention

[0010] These embodiments can provide a stable and effective automotive steering system. Brief explanation of the drawing

[0011] FIGS. 1 and FIGS. 2 are schematic diagrams schematically illustrating an automobile steering system according to the embodiments thereof. FIGS. 3 to 12 are drawings showing parts of an automobile steering device according to the embodiments of the present invention. FIG. 13 is a diagram illustrating a method for estimating a rack stroke range based on the difference between first rotation information and second rotation information according to the present embodiment. FIGS. 14 and FIGS. 15 are perspective views showing parts of an automobile steering device according to the embodiments. FIG. 16 is a schematic diagram showing an automobile steering system according to the embodiments thereof. Specific details for implementing the invention

[0012] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. In assigning reference numerals to the components of each drawing, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings. Furthermore, in describing the embodiments, if it is determined that a detailed description of related known components or functions may obscure the essence of the technical concept, such detailed description may be omitted. Where terms such as "comprising," "having," or "consisting of" are used in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it may include a plural unless otherwise specified.

[0013] Additionally, terms such as first, second, A, B, (a), (b), etc., may be used to describe the components of the present disclosure. These terms are used merely to distinguish the components from other components, and the nature, order, sequence, or number of the components are not limited by such terms.

[0014] In describing the positional relationship of components, where it is stated that two or more components are "connected," "combined," or "joined," it should be understood that while the two or more components may be directly "connected," "combined," or "joined," they may also be "connected," "combined," or "joined" with other components "intervened." Here, the other components may be included in one or more of the two or more components that are "connected," "combined," or "joined" with one another.

[0015] In describing the temporal flow relationship regarding components, methods of operation, or methods of production, for example, when the temporal or sequential relationship is described using "after," "following," "next," or "before," it may include cases where the relationship is not continuous unless "immediately" or "directly" is used.

[0016] Meanwhile, where numerical values ​​or corresponding information regarding a component (e.g., levels, etc.) are mentioned, even without separate explicit notation, the numerical values ​​or corresponding information may be interpreted as including a range of error that may occur due to various factors (e.g., process factors, internal or external shocks, noise, etc.).

[0017] Unlike conventional structures that physically connect the steering wheel to the road wheels, steer-by-wire steering systems utilize electronic signals via wires to control the vehicle's steering. Vehicle behavior control using wires is applied to various parts, such as the brakes. However, steer-by-wire steering systems require stable technical support, as interruptions in electronic signals can lead to the inability to control the vehicle. Furthermore, there is a need for technological advancements in terms of miniaturization and manufacturing costs.

[0018] In this disclosure, we propose various structural and control technologies that can satisfy stability, miniaturization, and manufacturing costs in a steer-by-wire steering system. For example, in this disclosure, multiple motors may be provided to move a rack bar to ensure redundancy and provide appropriate torque. Regarding the placement positions of the motors and rack bars, embodiments are described based on various effects.

[0019] Meanwhile, when configuring a steering system in a steer-by-wire manner, the pinion can be eliminated to achieve cost reduction and miniaturization. However, in this case, a problem may arise where the rack bar rotates as it moves according to the driving of the motor. The present disclosure also presents various embodiments regarding the structure of a rotation prevention member to solve this problem.

[0020] Furthermore, estimating the absolute position of the rack bar in a steer-by-wire steering system is crucial for accurate steering of the vehicle. However, sensors for estimating the absolute position of the rack bar may be vulnerable to impact, dust, water, etc. Additionally, multiple sensors may be required to ensure redundancy. This disclosure discloses various embodiments regarding the use of absolute angle sensors to estimate the position of the rack bar, or the use of sensors equipped in conventional motors, etc. Furthermore, the operation of a control device for estimating the position of the rack bar relatively is also disclosed.

[0021] The structure, motor, anti-rotation member, sensor, and control operation of the steering device described in this specification exist in various embodiments for each part. The embodiments for each part can be applied to the steering device in any combination.

[0022] FIGS. 1 and 2 are schematic diagrams showing a steering device for an automobile according to the embodiments of the present invention; FIGS. 3 to 12 are diagrams showing a part of a steering device for an automobile according to the embodiments of the present invention; FIG. 13 is a diagram for explaining a method for estimating a rack stroke range based on the difference between first rotation information and second rotation information according to the present invention; FIGS. 14 and 15 are perspective views showing a part of a steering device for an automobile according to the embodiments of the present invention; and FIG. 16 is a schematic diagram showing a steering device for an automobile according to the embodiments of the present invention.

[0023] First, referring to FIGS. 1 and FIGS. 2, the steering device according to the embodiments has an angle sensor (105) and a torque sensor (107) coupled to one side of a steering shaft (103) connected to a steering wheel (101).

[0024] In the case of autonomous driving mode, the electronic control unit (110) controls the output value transmitted to the steering column motor (120), the first motor (145), and the second motor (147) using electrical signals transmitted from various sensors mounted on the vehicle as input values.

[0025] Additionally, in the case of driver driving mode, the electronic control unit (110) controls the output value transmitted to the steering column motor (120), the first motor (145), and the second motor (147) by using the electric signal transmitted from the angle sensor (105) and the torque sensor (107) that detect the driver's steering wheel (101) operation, and the electric signals transmitted from various other sensors mounted on the vehicle as input values.

[0026] However, in these embodiments, the angle sensor (105) and the torque sensor (107) are each provided as an example, but it should be noted that they may be integrated into a single torque angle sensor.

[0027] The steering column motor (120) can be connected to a reduction gear (not shown) that reduces the rotational speed of the motor.

[0028] The steering column motor (120) provides a reaction force to the steering shaft (103) so that the driver can feel a steering reaction force in the opposite direction when operating the steering wheel (101) during normal driving, thereby providing the driver with an appropriate steering sensation. Therefore, the steering column motor (120) may be described as a reaction force motor. However, as shown below, the steering column motor (120) can operate according to autonomous steering as well as provide a reaction force when operating in autonomous driving mode, so it is described as a steering column motor (120) instead of the term reaction force motor.

[0029] In addition, the steering column motor (120) rotates the steering shaft (103) so that autonomous steering is performed under the control of the electronic control unit (110) without the driver's will intervening when the autonomous driving mode is operated.

[0030] In addition, in the steer-by-wire steering system, since the steering wheel (101) is not mechanically connected to the rack bar (130) and the road wheel (131), a mechanical limiting device is required to prevent the steering shaft (103) from rotating indefinitely when the driver operates the steering wheel (101).

[0031] Accordingly, in these embodiments, a rotation angle limiting device (125) that prevents infinite rotation of the steering shaft (103) may be provided.

[0032] The first motor (145) and the second motor (147) move the rack bar (130) through the rack-by-movement device (140) to perform steering of both road wheels (131) through the tie rod (133) and knuckle arm (135).

[0033] The rack-by-movement device (140) is composed of a ball nut (141) that rotates and moves the rack bar (130) in the axial direction by being coupled to the rack bar (130) via a ball (144), a nut pulley (143) provided on the outer surface of the ball nut (141), a first motor pulley (142a) provided on the first motor (145) and connected to the nut pulley (143) and the belt (149), and a second motor pulley (142b) provided on the second motor (147) and connected to the belt (149) between the nut pulley (143) and the first motor pulley.

[0034] And, a ball (144) is coupled between the rack screw groove formed on the outer surface of the rack bar (130) and the nut screw groove formed on the inner surface of the ball nut (141), so that when the ball nut (141) rotates, the rack bar (130) moves in the axial direction.

[0035] However, for convenience of explanation, the drawings in the embodiments shown here illustrate, as an example, the angle sensor (105) and torque sensor (107) provided on the steering shaft (103), the vehicle speed sensor (102) for sending steering information to the electronic control unit (110), the ultrasonic sensor (104), and the image sensor (106). However, various other sensors such as radar and lidar may be provided, and a detailed description thereof will be omitted below.

[0036] In such a steer-by-wire steering system, since the steering wheel (101) is not mechanically connected to the rack bar (130) and the road wheel (131), a mechanical limiting device is required to prevent rotation of the rack bar (130) due to the rotational torque of the ball nut (141) rotated by the rack-by-movement device (140).

[0037] Accordingly, in the present embodiments, a rotation prevention member (150) that prevents rotation of the rack bar (130) while supporting axial movement of the rack bar (130) may be provided.

[0038] However, in FIGS. 1 and 2, one rotation prevention member (150) is provided on one side of the rack bar (130) as an example, but it should be noted that the number of rotation prevention members (150) and the axial position of the rotation prevention members (150) may be changed according to the output of the first motor (145) and the second motor (147) and the rotational force design value of the ball nut (141) of the rack-by-moving device (140).

[0039] As shown in FIGS. 1 and 2, the first motor (145) and the second motor (147) can be arranged such that the axis (145a) of the first motor (145) and the axis (147a) of the second motor (147) are parallel to the center axis of the rack bar (130).

[0040] Thus, by arranging the positions of the first motor (145) and the second motor (147) as shown in FIGS. 1 and 2, the volume of the first motor (145), the second motor (147), and the rack bar (130) becomes compact, and the assembly process of the first motor (145), the first belt (149a), the second motor (147), and the second belt (149b) can be simplified.

[0041] Referring to FIG. 2, in case either the first motor sensor (145s) or the second motor sensor (147s) becomes inoperable, a separate rotating gear (139) that rotates by meshing with the rack gear (130b) is installed on one side of the rack bar (130), and a rotation angle sensor (137s) that detects the rotation angle of the rotating gear (139) may be provided.

[0042] The rotating gear (139) can be installed to be supported in a rack housing (not shown) via a bearing (not shown) and to rotate, and the rotation angle sensor (137s) can be installed on the shaft (137) of the rotating gear (139) to detect the rotation angle of the rotating gear (139) and transmit it to the electronic control unit (110).

[0043] Accordingly, even if either the first motor sensor (145s) or the second motor sensor (147s) becomes inoperable, the electronic control unit (110) can calculate the movement position of the rack bar (130) based on the gear ratio of the rack gear (130b) and the rotational gear (139) stored in advance and the rotational angle received from the rotational angle sensor (137s), and control the output value transmitted to the first motor (145) and the second motor (147).

[0044] Meanwhile, various embodiments of a rotation prevention member that can be provided in the aforementioned steering device will be described below with reference to the drawings.

[0045] Referring to FIGS. 3 to 13, the anti-rotation member (150) in the embodiments described above will be examined in more detail as follows.

[0046] As shown in FIG. 3, the anti-rotation member (150) is coupled to one side and the other side of the rack bar (130) in the radial direction to support the rack bar (130) from both sides, thereby preventing the rack bar (130) from rotating about the central axis.

[0047] The anti-rotation member (150) may include a shaft (230) that supports a support surface (130-1) formed on the outer surface of a rack bar (130), and a support yoke (240) that supports the outer surface of a rack bar (130) opposite to the position where the shaft (230) is supported.

[0048] The support surface (130-1) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0049] This support surface (130-1) is formed by being recessed on the outer surface of the rack bar (130) and can be formed as a curved or flat surface.

[0050] The support surface (130-1) is formed to be long in the axial direction so that it can be supported on the shaft (230) when the rack bar (130) moves in the axial direction.

[0051] The support surface (130-1) may be provided with a coating layer formed of a low-friction material having a low coefficient of friction, such as fluoropolymer or ceramic, to minimize friction with the shaft (230).

[0052] The shaft (230) supporting the support surface of the rack bar (130) may largely include an upper support portion (231), a body portion (233), and a lower support portion (235).

[0053] The shaft (230) is supported by the rack housing (see 160 in FIG. 10) when the rack bar (130) moves and rotates, and the body part (233) supports the support surface (130-1), thereby preventing the rack bar (130) from rotating.

[0054] A needle bearing (236) may be attached to the body part (233) to minimize friction with the support surface (130-1).

[0055] An upper support member (231) with an enlarged diameter is provided on the upper side of the body member (233), and an upper bearing (234) can be coupled to the upper support member (231) to be rotatably supported on the rack housing.

[0056] A top plug (232) may be attached to the upper side of the upper support member (231) to prevent foreign substances from the outside from entering the rack housing.

[0057] A lower support member (235) with a reduced diameter is provided on the lower side of the body member (233), and a lower bearing (238) can be coupled to the lower support member (235) to be rotatably supported on the rack housing.

[0058] A support yoke (240) that supports the outer surface of the rack bar (130) opposite the position where the shaft (230) is supported prevents the rack bar (130) from rotating by supporting the rack bar (130) toward the shaft (230) when the rack bar (130) moves.

[0059] The support yoke (240) may have a curved support portion (241) formed at its end with a curve identical to the outer surface of the rack bar (130) so as to be closely supported on the outer surface of the rack bar (130).

[0060] Since the support yoke (240) is required to have a certain degree of rigidity and elasticity, it may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0061] An elastic ring (245) can be attached to the outer surface of the support yoke (240) to prevent rattle noise with the rack housing.

[0062] One or more elastic rings (245) may be attached to the outer surface of the support yoke (240).

[0063] Since the elastic ring (245) is required to be formed of a material capable of absorbing vibration and noise while having a predetermined elasticity and rigidity, it may be formed of one or more materials selected from the group consisting of NR (Natural Rubber), NBR (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer), FPM (Fluoro Rubber), SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), urethane, silicone, etc., which have such properties.

[0064] A yoke plug (243) that is press-fitted or screw-coupled to the rack housing to fix the position of the support yoke (240) may be attached to the end of the support yoke (240).

[0065] Additionally, an elastic body is combined between the support yoke (240) and the yoke plug (243) to elastically support the support yoke (240) toward the rack bar (130).

[0066] As shown in FIG. 4, the anti-rotation member (150) is coupled to one side and the other side of the rack bar (130) in the radial direction to support the rack bar (130) from both sides, thereby preventing the rack bar (130) from rotating about the central axis.

[0067] The anti-rotation member (150) may include a needle bearing (220) that supports a support surface (130-1) formed on the outer surface of a rack bar (130), a support yoke (225) to which the needle bearing (220) is rotatably coupled, and a rack bush (229) that supports the outer surface of the rack bar (130) opposite to the position where the needle bearing (220) is supported.

[0068] The support surface (130-1) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0069] This support surface (130-1) is formed by being recessed on the outer surface of the rack bar (130) and can be formed as a curved or flat surface.

[0070] The support surface (130-1) is formed to be long in the axial direction so that it can be supported by the needle bearing (220) when the rack bar (130) moves in the axial direction.

[0071] The support surface (130-1) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the needle bearing (220).

[0072] A needle bearing (220) supporting the support surface (130-1) of a rack bar (130) has a support shaft (221) provided at its center and fixed to the support yoke (225) so that it can be rotatably supported on the support yoke (225).

[0073] The outer ring (222) of the needle bearing (220) is supported on the support surface (130-1) and rotates when the rack bar (130) moves, thereby preventing the rack bar (130) from rotating.

[0074] The outer ring (222) of the needle bearing (220) can be positioned at a location protruding from the end of the support yoke (225) so as to be supported on the support surface (130-1).

[0075] The support yoke (225) prevents rotation of the rack bar (130) by supporting the needle bearing (220) toward the support surface (130-1) when the rack bar (130) moves.

[0076] Since the support yoke (225) is required to have a certain degree of rigidity and elasticity, it may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0077] An elastic ring (226) can be attached to the outer surface of the support yoke (225) to prevent rattle noise with the rack housing (160).

[0078] One or more elastic rings (226) may be attached to the outer surface of the support yoke (225).

[0079] Since the elastic ring (226) is required to be formed of a material capable of absorbing vibration and noise while having a certain elasticity and rigidity, it may be formed of one or more materials selected from the group consisting of NR (Natural Rubber), NBR (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer), FPM (Fluoro Rubber), SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), urethane, silicone, etc., which have such properties.

[0080] A yoke plug (227) that fixes the position of the support yoke (225) by being press-fitted or screw-coupled to the rack housing (160) can be attached to the end of the support yoke (225).

[0081] Additionally, an elastic body (228) is combined between the support yoke (225) and the yoke plug (227) to elastically support the support yoke (225) toward the rack bar (130).

[0082] The rack bushing (229) supporting the outer surface of the rack bar (130) opposite the position where the needle bearing (220) is supported may be formed in a semi-cylindrical shape with a portion of the outer surface cut out.

[0083] The rack bush (229) prevents rotation of the rack bar (130) by supporting the rack bar (130) toward the radial needle bearing (220) when the rack bar (130) moves.

[0084] The rack bush (229) can be formed with the same curve as the outer surface of the rack bar (130) so as to be closely supported on the outer surface of the rack bar (130).

[0085] A bushing connection groove (166-1) to which a rack bushing (229) is connected may be formed on the inner surface of the rack housing (160).

[0086] The rack bush (229) may have a fixing projection (229a) formed on the outer surface of the end to prevent the axial position from shifting or rotating when the rack bar (130) moves.

[0087] A fixing groove (166-2) to which a fixing projection (229a) is coupled may be formed on the inner surface of the rack housing (160).

[0088] Since the rack bush (229) is required to have a certain degree of rigidity and elasticity, it may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0089] As shown in FIG. 5, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing (160) and can prevent the rack bar (130) from rotating about the central axis.

[0090] The anti-rotation member (150) may include a support member (210) having one end supported in a rack support groove (132) formed on the outer surface of a rack bar (130) and the other end supported in a housing groove (162) formed on the inner surface of a rack housing (160), and an elastic member (212) coupled to the support member (210) to elastically support the inner surface of the rack housing (160).

[0091] The rack support groove (132) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0092] These rack support grooves (132) are formed by being recessed on the outer surface of the rack bar (130) and can be formed as curved or flat surfaces.

[0093] The rack support groove (132) is formed to be long in the axial direction so that it can be supported by the support member (210) when the rack bar (130) moves in the axial direction.

[0094] The rack support groove (132) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the support member (210).

[0095] A housing groove (162) is formed at a position facing the rack support groove (132) in the radial direction, in which the other end of the support member (210) is supported.

[0096] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0097] These housing grooves (162) are formed by being recessed on the inner circumference of the rack housing (160) so that when the rack bar (130) moves axially, the support member (210) prevents the rack bar (130) from rotating, and can be formed as curved or flat surfaces.

[0098] The support member (210) has one end and the other end connected to the rack support groove (132) and the housing groove (162), and a connecting groove (211) is formed at the other end to which an elastic member (212) is connected.

[0099] Since the support member (210) is required to have a certain degree of rigidity and elasticity, it may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0100] The elastic member (212) is coupled to the coupling groove (211) of the support member (210) and elastically supports the inner surface of the rack housing (160), thereby supporting the support member (210) toward the rack bar (130) so that when the rack bar (130) moves in the axial direction, the support member (210) does not collide with the inner surface of the rack housing (160) and maintains a certain distance.

[0101] Therefore, rattle noise between the support member (210) and the rack housing (160) can be prevented.

[0102] The elastic member (212) can be formed from an arched thin plate.

[0103] A plug bolt (215) to prevent the support member (210) from coming off can be coupled to the inner surface of the rack housing (160) at the axial end of the support member (210).

[0104] The plug bolt (215) can be pressed into the inner surface of the rack housing (160) to be joined.

[0105] The plug bolt (215) includes a support portion (215a) that supports the support member (210) in the axial direction, and a fixing portion (215b) that is connected to the support portion (215a) and fixed to the inner circumference of the rack housing (160).

[0106] A screw portion is formed on the outer surface of the fixed portion (215b) so that it can be screw-coupled to the inner surface of the rack housing (160).

[0107] Additionally, a fixing member (217) can be attached to the axial end of the plug bolt (215) to prevent loosening and detachment of the plug bolt (215).

[0108] The fixing member (217) may have a fixing projection (217a) formed to protrude radially on the outer surface.

[0109] A fixing groove (164) may be formed on the inner surface of the rack housing (160) in which a fixing projection (217a) of a fixing member (217) is inserted and supported.

[0110] As shown in FIG. 6, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing, and can prevent the rack bar (130) from rotating about the central axis.

[0111] The anti-rotation member (150) may include a support bush (205) that supports a support surface (130-1) formed on the outer surface of a rack bar (130), a bush holder (200) that is coupled to the outer surface of the rack bar (130) and has the support bush (205) supported on its inner surface, and an elastic member (207) that is coupled between the bush holder (200) and the support bush (205) to elastically support the support bush (205) toward the rack bar (130).

[0112] The support surface (130-1) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0113] This support surface (130-1) is formed by being recessed on the outer surface of the rack bar (130) and can be formed as a curved or flat surface.

[0114] The support surface (130-1) is formed to be long in the axial direction so that it can be supported by the support bush (205) when the rack bar (130) moves in the axial direction.

[0115] The support surface (130-1) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the support bush (205).

[0116] A housing groove (162) is formed on the inner surface of the rack housing (160) at a position facing the support surface (130-1) in the radial direction, to which a bush holder (200) is coupled and supported.

[0117] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0118] These housing grooves (162) are formed by being recessed into the inner surface of the rack housing (160) and can be formed as curved or flat surfaces.

[0119] Additionally, a stepped portion (163) is formed on the inner surface of the rack housing (160) such that the diameter is expanded at the end of the housing groove (162), and the end of the stepped portion (163) may be formed to be open in the axial direction.

[0120] The bush holder (200) has a cylinder shape with one side cut in the radial direction, and an inner protruding surface is formed at a position facing the cut portion to protrude radially inward.

[0121] Additionally, a bushing coupling groove (203) to which a support bushing (205) is coupled is formed on the inner protruding surface (201), and a flange portion (206) that protrudes radially and is supported by the stepped portion (163) of the rack housing (160) may be formed at the axial end of the bushing holder (200).

[0122] The flange portion (206) is supported by the step portion (163) and prevents the bush holder (200) from coming off when the rack bar (130) moves axially.

[0123] The support bush (205) coupled to the bush coupling groove (203) of the bush holder (200) includes a protruding support portion (205a) formed to protrude from the center and to which an elastic member (207) is coupled.

[0124] The elastic member (207) is formed in an annular shape, and the inner and outer surfaces are formed in a cone shape with axial steps, so that the protruding support member (205a) can be coupled to the inner surface of the elastic member (207).

[0125] This elastic member (207) elastically supports the support bush (205) toward the rack bar (130) between the bush holder (200) and the support bush (205), thereby maintaining a certain distance (202) so that the support bush (205) does not collide with the bush holder (200) when the rack bar (130) moves axially.

[0126] Therefore, rattle noise between the support bush (205) and the bush holder (200) can be prevented.

[0127] Since these bush holders (200) and support bushes (205) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0128] As shown in FIG. 7, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing (160) and can prevent the rack bar (130) from rotating about the central axis.

[0129] The anti-rotation member (150) may include a rack bush (250) having an inner support member (251) supported by a rack support groove (132) formed on the outer surface of a rack bar (130) and an outer support member (253) supported by a housing groove (162) formed on the inner surface of a rack housing (160), and an elastic member (252) coupled to the outer surface of the rack bush (250) to elastically support the rack bush (250).

[0130] The rack support groove (132) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0131] These rack support grooves (132) are formed by being recessed on the outer surface of the rack bar (130) and can be formed as curved or flat surfaces.

[0132] The rack support groove (132) is formed to be long in the axial direction so that it can be supported by the rack bushing when the rack bar (130) moves in the axial direction.

[0133] The rack support groove (132) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the rack bush (250).

[0134] An inner support portion (251) is formed on the inner surface of the rack bushing (250) at a position facing the rack support groove (132) in the radial direction, protruding inward in the radial direction.

[0135] An outer support portion (253) is formed on the outer surface of the rack bush (250) to protrude radially outward and is coupled to the housing groove (162).

[0136] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0137] The housing groove (162) is formed as a recess on the inner surface of the rack housing (160) and can be formed as a curved or flat surface.

[0138] The outer support members (253) are spaced out in the circumferential direction from the outer surface of the rack bush (250), and two or more may be formed.

[0139] The outer support member (253) may be formed as a pair on both sides in the circumferential direction at a position facing the inner support member (251) on the outer surface of the rack bush (250).

[0140] Since such rack bushings (250) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0141] The elastic member (252) coupled to the outer surface of the rack bush (250) can be formed in a ring shape.

[0142] Since the elastic member (252) is required to be formed of a material capable of absorbing vibration and noise while having a predetermined elasticity and rigidity, it may be formed of one or more materials selected from the group consisting of NR (Natural Rubber), NBR (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer), FPM (Fluoro Rubber), SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), urethane, silicone, etc., which have such properties.

[0143] A coupling groove (252-1) to which an elastic member (252) is coupled may be formed on the outer surface of the rack bush (250).

[0144] The rack bush (250) may have an axially cut section (254) formed to facilitate elastic deformation in the radial direction.

[0145] The incisions (254) are spaced apart in the circumferential direction, and two or more may be formed.

[0146] The cut portion (254) may be formed so that one end of the rack bush (250) is open or the other end is open.

[0147] The incision (254) formed with one end open and the incision (254) formed with the other end open may be spaced apart in the circumferential direction and formed staggered from each other.

[0148] Accordingly, by elastically supporting the rack bush (250) in the radial direction by the tightening force of the elastic member (252), a certain distance is maintained so that the rack bush (250) does not collide with the rack housing (160) when the rack bar (130) moves in the axial direction.

[0149] Therefore, rattle noise between the rack bush (250) and the rack housing (160) can be prevented.

[0150] As shown in FIG. 8, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing (160) and can prevent the rack bar (130) from rotating about the central axis.

[0151] The anti-rotation member (150) may include a rotating member (191) that supports a supporting surface (130-1) formed on the outer surface of a rack bar (130), and a support bush (190) that is rotatably coupled to the rotating member (191) and coupled to a housing groove (162) formed on the inner surface of a rack housing (160).

[0152] The support surface (130-1) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0153] This support surface (130-1) is formed by being recessed on the outer surface of the rack bar (130) and can be formed as a curved or flat surface.

[0154] The support surface (130-1) is formed to be long in the axial direction so that it can be supported by the rotating member (191) when the rack bar (130) moves in the axial direction.

[0155] Two or more support surfaces (130-1) may be formed on the outer surface of the rack bar (130) at circumferentially spaced apart.

[0156] The support surfaces (130-1) can be formed as a pair at positions facing each other in the radial direction of the rack bar (130).

[0157] The rotating member (191) may be a roller or ball that is coupled to the inner surface of the support bush (190) and supported on the support surface (130-1) of the rack bar (130).

[0158] The rotating member (191) can be connected to both the inner and outer sides of the support bush (190).

[0159] The support surface (130-1) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the rotating member (191).

[0160] A housing groove (162) is formed on the inner surface of the rack housing (160) at a position facing the support surface rotating member (191) in the radial direction, to which a support bush (190) is coupled and supported.

[0161] The support bush (190) is rotatably coupled to the rotating member (191) and coupled to the housing groove (162) of the rack housing (160).

[0162] Since such support bushes (190) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0163] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0164] These housing grooves (162) are formed by being recessed into the inner surface of the rack housing (160) and can be formed as curved or flat surfaces.

[0165] As shown in FIG. 9, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing, and can prevent the rack bar (130) from rotating about the central axis.

[0166] The anti-rotation member (150) may include a rack bushing (180) having a rotational support member (183) that is coupled to a rack support groove (132) formed on the outer surface of a rack bar (130) and a housing groove (162) formed on the inner surface of a rack housing (160) to provide rotational support, an elastic support member (185) that is coupled to a rack support groove (132) formed on the outer surface of a rack bar (130) and a housing groove (162) formed on the inner surface of a rack housing (160) to provide elastic support, and a connecting member (181) that connects the rotational support member (183) and the elastic support member (185).

[0167] The rack support groove (132) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0168] These rack support grooves (132) are formed by being recessed on the outer surface of the rack bar (130) and can be formed as curved or flat surfaces.

[0169] The rack support groove (132) is formed to be long in the axial direction so that it can be supported by the rotational support part (183) and the elastic support part (185) when the rack bar (130) moves in the axial direction.

[0170] A housing groove (162) is formed on the inner surface of the rack housing (160) at a position facing the rack support groove (132) in the radial direction.

[0171] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0172] The housing groove (162) is formed as a recess on the inner surface of the rack housing (160) and can be formed as a curved or flat surface.

[0173] The rack support groove (132) and the housing groove (162) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction with the rack bush (180).

[0174] The rack bush (180) may be equipped with two or more rotating support members (183).

[0175] The rack bush (180) may be equipped with two or more elastic support members (185).

[0176] A ball may be coupled to the rotational support member (183), and two or more balls may be coupled and spaced apart in the axial direction.

[0177] The elastic support member (185) can be formed in a cylinder shape with one side open.

[0178] By elastically supporting the rack bush (180) in the rack support groove (132) and the housing groove (162) by the elastic deformation force of the elastic support part (185), a certain distance is maintained so that the rack bush (180) does not collide with the rack housing (160) when the rack bar (130) moves in the axial direction.

[0179] Therefore, rattle noise between the rack bush (180) and the rack housing (160) can be prevented.

[0180] As shown in FIG. 10, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the inner surface of the rack housing (160) and can prevent the rack bar (130) from rotating about the central axis.

[0181] The anti-rotation member (150) may include a rack bushing (170) having a first support member (171) that supports a support surface (130-1) formed on the outer surface of a rack bar (130), and a second support member (175) that is connected to the first support member (171), supports the outer surface of the rack bar (130), and has a fixing projection (173) formed on the outer surface that is coupled to a housing groove (162) formed on the inner surface of a rack housing (160).

[0182] The support surface (130-1) formed on the outer surface of the rack bar (130) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0183] This support surface (130-1) is formed by being recessed on the outer surface of the rack bar (130) and can be formed as a curved or flat surface.

[0184] The support surface (130-1) is formed to be long in the axial direction so that it can be supported by the first support part (171) when the rack bar (130) moves in the axial direction.

[0185] The first support member (171) is supported such that its inner surface (171a) is in close contact with the support surface (130-1) of the rack bar (130), and its outer surface may be spaced apart from the inner surface of the rack housing (160).

[0186] A coating layer formed of a low-friction material, such as fluoropolymer or ceramic, may be provided on the support surface (130-1) and the outer surface of the rack bar to minimize friction with the rack bush (170).

[0187] The second support member (175) is connected to the first support member (171) in a circumferential direction and is formed to wrap around the outer surface of the rack bar (130).

[0188] The outer surface of the second support member (175) is provided with a fixing projection (173) formed to protrude radially.

[0189] A housing groove (162) is formed on the inner surface of the rack housing (160) so that the fixing projection (173) of the second support part (175) is coupled thereto to prevent the rack bushing (170) from rotating.

[0190] The housing groove (162) can be formed by cutting or grinding the inner surface of the rack housing (160).

[0191] These housing grooves (162) are formed by being recessed into the inner surface of the rack housing (160) and can be formed as curved or flat surfaces.

[0192] Since such rack bushings (170) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0193] As shown in FIG. 11, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the guide cover (155) coupled to the rack housing (160), and can prevent the rack bar (130) from rotating about the central axis.

[0194] The anti-rotation member (150) may include a support member (151) coupled to the outer surface of the rack bar (130), a guide cover (155) coupled to the rack housing (160) and having the support member (151) supported on its inner surface, and a fastening member (159) that fixes the guide cover (155) to the rack housing (160).

[0195] A support member (151) is attached to the outer surface of the rack bar (130). The support member (151) is attached to a coupling groove (134) formed on the outer surface of the rack bar (130) by press-fitting or bonding, and the coupling groove (134) can be formed by cutting or grinding the outer surface of the rack bar (130).

[0196] These connecting grooves (134) are formed by being recessed on the outer surface of the rack bar (130) and can be formed as curved or flat surfaces.

[0197] A rack housing (160) located radially opposite to a support member (151) is formed to be open, and a guide cover (155) is attached to the open portion.

[0198] A support groove (155-1) in which a support member (151) is inserted and supported may be formed on the inner surface of the guide cover (155).

[0199] These support grooves (155-1) are formed axially so that the support member (151) can be supported when the rack bar (130) moves axially.

[0200] The support groove (155-1) can be formed in a trapezoidal shape that widens toward the support member (151).

[0201] The support member (151) can be formed in a trapezoidal shape that becomes narrower in width as it goes from the outer surface of the rack bar (130) toward the support groove (155-1).

[0202] Both sides of the support groove (155-1) are in close contact with and supported by the support member (151), and the inner side of the support groove (155-1) may be spaced apart from the end of the support member (151).

[0203] The support groove (155-1) or the support member (151) may be provided with a coating layer formed of a low-friction material, such as fluoropolymer or ceramic, to minimize friction.

[0204] The support groove (155-1) can be filled with grease to minimize friction with the support member (151).

[0205] The guide cover (155) can be fixed to the rack housing (160) by a fastening member (159).

[0206] Additionally, a fastening member (159) passes through between the guide cover (155) and the rack housing (160), and an elastic member (157) that elastically supports the guide cover (155) and the rack housing (160) can be coupled.

[0207] A sealing member (158) that prevents moisture or dust from entering from the outside may be applied to the end of the guide cover (155) and the outer surface of the rack housing (160).

[0208] Since these support members (151) and guide covers (155) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0209] As shown in FIG. 12, the anti-rotation member (150) is supported on the outer surface of the rack bar (130) and the housing cover (154) which is coupled to the rack housing (160), and can prevent the rack bar (130) from rotating about the central axis.

[0210] The anti-rotation member (150) may include a support member (151) supported on the outer surface of the rack bar (130), a housing cover (154) fixed to the rack housing (160) and having the support member (151) coupled to its inner surface, and a fastening member (159) that fixes the housing cover (154) to the rack housing (160).

[0211] A rack support groove (134) is formed on the outer surface of the rack bar (130) to support a support member (151).

[0212] The rack support groove (134) is formed to be long in the axial direction so that the support member (151) can be supported when the rack bar (130) moves in the axial direction.

[0213] These rack support grooves (134) are formed by being recessed on the outer surface of the rack bar (130) and can be formed as curved or flat surfaces.

[0214] A rack housing (160) located radially opposite to the rack support groove (134) is formed to be open, and a housing cover (154) is attached to the open portion.

[0215] A cover support groove (156) to which a support member (151) is coupled may be formed on the inner surface of the housing cover (154).

[0216] The rack support groove (134) can be formed in a trapezoidal shape that widens toward the housing cover (154).

[0217] The support member (151) can be formed in a trapezoidal shape that becomes narrower in width as it goes from the cover support groove (156) toward the rack support groove (134).

[0218] Both sides of the rack support groove (134) are in close contact with and supported by the support member (151), and the inner side of the rack support groove (134) may be spaced apart from the end of the support member (151).

[0219] A coating layer formed of a low-friction material, such as fluoropolymer or ceramic, may be provided on the rack support groove (134) or the support member (151) to minimize friction.

[0220] The rack support groove (134) may be filled with grease to minimize friction with the support member (151).

[0221] The housing cover (154) can be fixed to the rack housing (160) by a fastening member (159).

[0222] A sealing member (158) that prevents moisture or dust from entering from the outside may be applied to the end of the housing cover (154) and the outer surface of the rack housing (160).

[0223] Since these support members (151) and housing covers (154) are required to have a certain degree of rigidity and elasticity, they may be formed from one or more materials selected from the group consisting of polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), phenol formaldehyde (PF), etc.

[0224] As described above, a plurality of motors can be provided in a steer-by-wire steering system to provide steering force to the rack bar. In addition, a member is configured to prevent rotation of the rack bar, so that unnecessary rotation of the rack bar can be prevented even when the pinion is removed.

[0225] Below, various embodiments of the method for calculating the rack bar position in such a steer-by-wire steering system are described. The method for calculating the rack bar position described below can be applied regardless of the position and shape of the motor described above. Alternatively, the method for calculating the rack bar position may be applied to the specific position and shape of the motor described above. Furthermore, the method for calculating the rack bar position may be applied regardless of the presence or absence of a rotation-prevention member, or it may be applied in combination with a specific rotation-prevention member.

[0226] In a steer-by-wire steering system, the electronic control unit (110) can control the operation of the drive motor (e.g., 145, 147) using each piece of information. To do this, the electronic control unit (110) can receive information from one or more sensors provided in the vehicle.

[0227] The aforementioned one or more sensors include various sensors configured in the vehicle necessary for steering, such as a steering angle sensor, a steering torque sensor, a vehicle speed sensor, and a rack position sensor. However, as described above, a pinion may not exist when the rack bar is configured to move by the first motor and the second motor. In this case, a rack position sensor for sensing the absolute position of the rack bar may not exist. Alternatively, a rack position sensor for sensing the absolute position of the rack bar may be installed on the gearbox connecting the first motor, the second motor, and the rack bar.

[0228] First, various embodiments for verifying the absolute position (or absolute angle) of a rack bar are described. Subsequently, embodiments using an absolute angle sensor to sense the absolute position (or absolute angle) of the rack bar are described.

[0229] The electronic control unit (110) may control the operation of the steering column motor (120). The electronic control unit (110) may be composed of a single physically integrated chip. Alternatively, the electronic control unit (110) may be composed of two or more chips. If it is composed of two or more chips, it may be divided into a reaction motor, a driving motor, a main control unit, etc., and may perform the aforementioned operations.

[0230] Meanwhile, the electronic control unit (110) can control the operation of a plurality of drive motors (e.g., 145, 147) to control the direction of travel of the vehicle according to the driver's steering intention.

[0231] The electronic control unit (110) may be composed of two or more units to ensure redundancy, and each electronic control unit (110) may perform the same operation. Alternatively, among the electronic control units (110), the main electronic control unit may perform the aforementioned operation, and the sub electronic control unit may perform the aforementioned operation when a malfunction occurs in the main electronic control unit.

[0232] The electronic control unit (110) can receive various information and control the steering of the vehicle. In the case of controlling the rack bar using two motors in the aforementioned steer-by-wire (SBW) system, accurate steering control is possible only if the position information of the rack bar is accurately recognized.

[0233] To this end, the electronic control unit (110) can receive position information of the rack bar from the rack position sensor. Alternatively, if there is no rack position sensor, the electronic control unit (110) may directly estimate the position information of the rack bar using two motor position information.

[0234] For example, the electronic control unit (110) can receive rotation information of each motor from two motor position sensors. The rotation information of each motor may include rotation information of the first motor and rotation information of the second motor. The rotation information of the first motor may be received from a motor position sensor configured in the first motor. The rotation information of the second motor may be received from a motor position sensor configured in the second motor.

[0235] The motor position sensor can sense rotation information of each motor. The motor position sensor can detect the rotation of the motor shaft. Alternatively, the motor position sensor may detect the rotation of any rotating member connected to the motor shaft. The motor position sensor can sense rotation information between 0 and 360 degrees for the rotation of each motor. The motor position sensor can measure the rotation angle and position of the motor.

[0236] The motor position sensor may be an optical encoder sensor that detects position by illuminating a disk with light. Alternatively, the motor position sensor may be a magnetic encoder sensor that measures the rotor's position using a magnetic sensor. Or, the motor position sensor may be an incremental encoder sensor that measures relative position changes by outputting a constant pulse. Or, the motor position sensor may be an absolute encoder sensor that measures absolute position by outputting a unique value for a specific location. Such motor position sensors can provide precise position and speed information.

[0237] Meanwhile, a Hall sensor that measures position by detecting changes in magnetic flux of a rotor to which a permanent magnet is attached may also be used as a motor position sensor. Used in BLDC motors, a motor position sensor may be configured by arranging three Hall sensors with a phase difference of 120 degrees or 60 degrees. In addition, there are resolvers that measure position in an analog manner using voltage changes, and inductive position sensors that sense position using the principle of electromagnetic induction. The motor position sensor in this specification may utilize the various types of sensors described above.

[0238] As explained above, motor position sensors can measure absolute angle values ​​based on a specific position of the motor. Alternatively, motor position sensors can sense a relative position indicating how much the motor has moved from a reference position. Furthermore, motor position sensors can measure the electrical position of the rotor in BLDC and PMSM motors. However, motor position sensors differ in terms of price and size, as well as in terms of measurement values ​​and precision.

[0239] When measuring a single rotation angle to measure a rotation angle between 0 and 360 degrees, position detection is possible only during a single rotation. In this case, it is difficult to verify the absolute position because it is reset when rotating beyond one full revolution. Although motor position sensors capable of measuring multiple rotation angles exist, they require the use of absolute sensors and have the disadvantages of a complex structure and high cost.

[0240] The present disclosure provides a method for obtaining absolute position information of a rack bar using two motor position information when each motor position sensor measures a relative position.

[0241] For example, two motors may be controlled to move the same rack bar but have different rotational speeds. In this case, the rotational information from the motor position sensors of the two motors may continuously change between 0 degrees and 360 degrees. If it is not an absolute angle sensor, this is not recorded or stored, and the rotational information sensed by the motor position sensor of the first motor may be one of the values ​​between 0 degrees and 360 degrees. Similarly, the rotational information sensed by the motor position sensor of the second motor may also be one of the values ​​between 0 degrees and 360 degrees.

[0242] The electronic control unit (110) can monitor rotation information of the first motor and rotation information of the second motor. The electronic control unit (110) estimates the absolute position of the rack bar using motor rotation information (motor position) generated from the two motors.

[0243] As explained above, the first motor and the second motor are connected to a single ball nut at different rotational speeds to move the rack bar. Therefore, even though the first and second motors rotate at different speeds, the ball nut must be rotated at the same speed. To achieve this, the motor pulley of the first motor and the motor pulley of the second motor may be configured with different gear ratios.

[0244] For example, the gear ratio can refer to the number of teeth on the motor pulley connected to the motor shaft of each motor, or to the diameter. This is because differences in diameter can effectively represent a difference in the gear ratio.

[0245] In this structure, the first motor and the second motor rotate at different rotational speeds, and the electronic control unit (110) can receive different motor rotation information.

[0246] The electronic control unit (110) can calculate the absolute position of the rack bar using preset information and motor rotation information of each motor.

[0247] For example, the difference in rotational speed between two motors can vary depending on the absolute position of the rack bar.

[0248] For example, the electronic control unit (110) can calculate the absolute position of the rack bar by monitoring the absolute angle change of the rotation information of each motor. For example, the electronic control unit (110) can determine the position of the rack bar using Equation 1.

[0249]

[0250] R represents the moving position of the rack bar, θ represents the phase difference between the first rotation information and the second rotation information, K represents the distance the rack bar has moved while the phase difference between the first rotation information and the second rotation information changes from 0 to 0 the next time the phase difference becomes 0 when the rack bar moves in one direction, and n represents the number of times the phase difference becomes 0 while the rack bar moves in one direction.

[0251] That is, the electronic control unit (110) can continuously monitor the phase difference between the first rotation information of the first motor and the second rotation information of the second motor and record the number of times the phase difference becomes zero, thereby cumulatively confirming the position of the rack bar.

[0252] As another example, the electronic control unit (110) can determine the position of the rack bar based on a preset reference value. The rack bar has a structurally limited range of movement. Therefore, taking into account that the rack bar cannot move infinitely, the position of the rack bar can be predicted in advance based on the values ​​of first rotation information and second rotation information. The first rotation information and second rotation information based on the predicted position of the rack bar can be stored in advance in the electronic control unit (110) in a table or other data storage form.

[0253] When the electronic control unit (110) receives rotation information of the motor, it can directly estimate the absolute position of the rack bar by comparing it with previously stored data. However, in this case, the first rotation information and the second rotation information must be designed to have different values ​​across the entire stroke range of the rack bar. Therefore, the difference in gear ratio between the first motor and the second motor must be set so that the first rotation information and the second rotation information do not overlap at two or more absolute positions of the rack bar.

[0254] For example, the electronic control unit (110) can estimate the absolute position of the rack bar using the following mathematical formula 2.

[0255]

[0256] ,

[0257] Rack bar position R = intersection of A and B, where m is a natural number greater than or equal to 1 and less than or equal to the maximum rack bar travel distance.

[0258] FIG. 13 is a diagram illustrating a method for estimating a rack stroke range based on the difference between first rotation information and second rotation information.

[0259] Referring to FIG. 13, the first rotation information and the second rotation information are shown in the situation of the rack bar position from 0 to 75, i.e., the rack displacement (mm), using two motor rotation information (motor angle). As described above, the first gear ratio and the second gear ratio can be adjusted so that there is no overlap between the first rotation information and the second rotation information in the value on the corresponding rack displacement.

[0260] FIG. 14 is an automobile steering device showing a case where the second motor pulley (142b) is coupled to the outside of the belt (149), and FIG. 15 is an automobile steering device showing a case where the second motor pulley (142b) is coupled to the inside of the belt (149).

[0261] In this way, by connecting the second motor pulley (142b) to the outer or inner side of the belt (149), the amount of compression, i.e., the tension of the belt (149), can be easily adjusted by adjusting only the position of the second motor pulley (142b).

[0262] These embodiments are applicable to both steer-by-wire steering systems and general steering systems.

[0263] Accordingly, FIGS. 14 and 15 below will be described as having a configuration common to both steer-by-wire steering systems and general steering systems.

[0264] Referring to FIGS. 1 and 2 together with FIGS. 14, a steering device for an automobile may be provided, comprising: a ball nut (141) that rotates and moves the rack bar (130) axially by being coupled to the rack bar (130) via a ball; a nut pulley (143) provided on the outer surface of the ball nut (141); a first motor pulley (142a) provided on the first motor (145) and coupled to the nut pulley (143) and belt (149); a second motor pulley (142b) provided on the second motor (147) and coupled to the belt (149) between the nut pulley (143) and the first motor pulley (142a); and an electronic control device (110) that controls an output value transmitted to the first motor (145) and the second motor (147) using an electrical signal as an input value.

[0265] Unlike a general belt (149), the belt (149) is provided with teeth on both the inner and outer surfaces, and the inner surface may be provided with inner belt teeth (149-1) and the outer surface may be provided with outer belt teeth (149-2).

[0266] On the outer surface of the nut pulley (143), a nut pulley tooth (143-1) that is coupled with the inner belt tooth (149-1) of the belt (149) may be provided, and on the outer surface of the first motor pulley (142a), a first motor pulley tooth (142-1) that is coupled with the inner belt tooth (149-1) of the belt (149) may be provided.

[0267] Additionally, the second motor pulley (142b) may be provided with a second motor pulley tooth (142-2) that is coupled to the outer belt tooth (149-2) of the belt (149) on its outer surface.

[0268] Here, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently.

[0269] That is, the first motor pulley reach (142-1) and the second motor pulley reach (142-2) are formed with different pitch circle diameters and the number of teeth.

[0270] And, since the first motor pulley reach (142-1) is engaged with the inner belt reach (149-1) and the second motor pulley reach (142-2) is engaged with the outer belt reach (149-2), the pitch of the first motor pulley reach (142-1) and the inner belt reach (149-1) is the same, and the pitch of the second motor pulley reach (142-2) and the outer belt reach (149-2) is also the same.

[0271] The first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control device (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control device (110).

[0272] Accordingly, the electronic control unit (110) can calculate the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s), and control the output value transmitted to the first motor (145) and the second motor (147).

[0273] That is, the electronic control unit (110) sets the angle formed by the reference point of the axis (145a) of the first motor (145) when the first motor (145) is stopped and the reference point of the axis (147a) of the second motor (147) when the second motor (147) is stopped as the first position value (or reference position value), and sets the angle formed by the reference point of the axis (145a) of the first motor (145) and the reference point of the axis (147a) of the second motor (147) after the operation of the first motor (145) and the second motor (147) as the second position value (or operating position value), and calculates the movement position of the rack bar (130) based on the difference between the reference position value (first position value) and the operating position value.

[0274] And, as with the calculation method described above, the difference between the reference position value and the operating position value can be formed from 0° to 360°, and the maximum movement amount of the rack bar (130) is set within this range, and the electronic control device (110) calculates the movement position of the rack bar (130) based on at least one of the pitch circle diameter ratio or tooth ratio of the first motor pulley (142a) and the nut pulley (143), the pitch circle diameter ratio or tooth ratio of the second motor pulley (142b) and the nut pulley (143), the outer diameter and inner diameter of the ball nut (141), and the outer diameter of the rack bar (130).

[0275] The electronic control unit (110) may set the difference between the reference position value and the operating position value as a movement value and calculate the movement position of the rack bar (130) by comparing it with preset data, in which case the movement value may be formed from 0° to 360° and the maximum movement amount of the rack bar (130) is set within this range.

[0276] Here, the preset data may be data that stores the amount of movement of the rack bar (130) corresponding to a movement value calculated based on at least one of the pitch circle diameter and number of teeth of the first motor pulley (142a) and the second motor pulley (142b), the pitch circle diameter and number of teeth of the nut pulley (143), the outer diameter and inner diameter of the ball nut (141), and the outer diameter of the rack bar (130).

[0277] Thus, by forming the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) differently, the electronic control unit (110) can calculate the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s), and control the output value transmitted to the first motor (145) and the second motor (147).

[0278] In addition, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) is the same, and the pitch of the inner belt reach (149-1) and the outer belt reach (149-2) can be formed differently.

[0279] That is, the first motor pulley (142-1) and the second motor pulley (142-2) have the same pitch as the gear module and are formed with the same pitch circle diameter and number of teeth, and the pitch of the inner belt tooth (149-1) and the outer belt tooth (149-2) can be formed differently.

[0280] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0281] Accordingly, the electronic control unit (110) can calculate the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s), and control the output value transmitted to the first motor (145) and the second motor (147).

[0282] In addition, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently, and the pitch of the inner belt reach (149-1) and the outer belt reach (149-2) may be formed differently.

[0283] That is, the first motor pulley (142-1) and the second motor pulley (142-2) are formed with different pitch circle diameters and number of teeth, and the inner belt tooth (149-1) and the outer belt tooth (149-2) can be formed with different pitches.

[0284] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0285] Accordingly, the electronic control unit (110) can calculate the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s), and control the output value transmitted to the first motor (145) and the second motor (147).

[0286] Meanwhile, FIG. 15 shows a case where the second motor pulley (142b) is coupled to the inner side of the belt (149). When FIG. 15 is referred to together with FIG. 1 and FIG. 2, a second motor pulley tooth (142-2) coupled to the inner belt tooth (149-1) may be provided on the outer surface of the second motor pulley (142b).

[0287] An inner belt tooth (149-1) is provided on the inner surface of the belt (149) and an outer belt tooth (149-2) is provided on the outer surface, and a nut pulley tooth (143-1) that is coupled with the inner belt tooth (149-1) may be provided on the outer surface of the nut pulley (143).

[0288] Additionally, a first motor pulley (142-1) coupled with an inner belt tooth (149-1) may be provided on the outer surface of the first motor pulley (142a), and a second motor pulley (142-2) coupled with an inner belt tooth (149-1) may be provided on the outer surface of the second motor pulley (142b).

[0289] Here, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently.

[0290] That is, the first motor pulley reach (142-1) and the second motor pulley reach (142-2) are formed with different pitch circle diameters and the number of teeth.

[0291] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0292] The electronic control unit (110) can control the output value transmitted to the first motor (145) and the second motor (147) by calculating the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s).

[0293] FIG. 16 shows a general steering device in which the steering wheel (101) and the road wheel (131) are connected by a mechanical configuration from the steering wheel to the road wheel.

[0294] The steering wheel (101) is coupled to the steering shaft (103), and the steering column (100) that accommodates it is fixed to the car body.

[0295] And, the steering shaft (103) is connected to the pinion shaft (109) via a universal joint (108), and generates linear motion of the rack bar (130) through the pinion gear (109a) and rack gear (130b), which steers the two road wheels (131) connected by the tie rod (133) and knuckle arm (135).

[0296] An angle sensor (105) and a torque sensor (107) for detecting the rotation angle and direction of the steering shaft (103), a vehicle speed sensor (102), an ultrasonic sensor (104), and an image sensor (106) for sending steering information of the vehicle to an electronic control unit (110) are provided. This is an example of various sensors, and additional sensors such as radar and lidar may be provided, and a detailed explanation thereof will be omitted below.

[0297] Referring to FIG. 16 together with FIG. 14 and 15, there is a ball nut (141) that rotates and moves the rack bar (130) axially by being coupled to the rack bar (130) via a ball, a nut pulley (143) provided on the outer surface of the ball nut (141), a first motor pulley (142a) provided on the first motor (145) and connected to the nut pulley (143) and the belt (149), a second motor pulley (142b) provided on the second motor (147) and coupled to the belt (149) between the nut pulley (143) and the first motor pulley (142a), an electronic control device (110) that controls an output value transmitted to the first motor (145) and the second motor (147) using an electrical signal as an input value, and one side is coupled to a steering shaft coupled to a steering wheel and the other side supports one side of the rack bar (130). An automobile steering device including a coupled pinion shaft may be provided.

[0298] Referring to FIG. 14 together with FIG. 16, the inner circumferential belt tooth (149-1) is provided on the inner circumferential surface of the belt (149) and the outer circumferential belt tooth (149-2) is provided on the outer circumferential surface, and the nut pulley (143) may be provided with a nut pulley tooth (143-1) that is coupled with the inner circumferential belt tooth (149-1) on the outer circumferential surface of the nut pulley (143).

[0299] On the outer surface of the first motor pulley (142a), a first motor pulley tooth (142-1) coupled with an inner belt tooth (149-1) may be provided, and on the outer surface of the second motor pulley (142b), a second motor pulley tooth (142-2) coupled with an outer belt tooth (149-2) may be provided.

[0300] Here, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently.

[0301] That is, the first motor pulley reach (142-1) and the second motor pulley reach (142-2) can be formed with different pitch circle diameters and the number of teeth.

[0302] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0303] The electronic control unit (110) can control the output value transmitted to the first motor (145) and the second motor (147) by calculating the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s).

[0304] In addition, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) is the same, and the pitch of the inner belt reach (149-1) and the outer belt reach (149-2) can be formed differently.

[0305] That is, the first motor pulley (142-1) and the second motor pulley (142-2) have the same pitch as the gear module and are formed with the same pitch circle diameter and number of teeth, and the pitch of the inner belt tooth (149-1) and the outer belt tooth (149-2) can be formed differently.

[0306] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0307] The electronic control unit (110) can control the output value transmitted to the first motor (145) and the second motor (147) by calculating the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s).

[0308] In addition, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently, and the pitch of the inner belt reach (149-1) and the outer belt reach (149-2) may be formed differently.

[0309] That is, the first motor pulley reach (142-1) and the second motor pulley reach (142-2) are formed with different pitch circle diameters and number of teeth, and the inner belt reach (149-1) and the outer belt reach (149-2) can be formed with different pitches.

[0310] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0311] The electronic control unit (110) can control the output value transmitted to the first motor (145) and the second motor (147) by calculating the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s).

[0312] Additionally, referring to FIG. 16 together with FIG. 15, a second motor pulley tooth (142-2) that is coupled with an inner belt tooth (149-1) may be provided on the outer surface of the second motor pulley (142b).

[0313] An inner belt tooth (149-1) is provided on the inner surface of the belt (149) and an outer belt tooth (149-2) is provided on the outer surface, and a nut pulley tooth (143-1) that is coupled with the inner belt tooth (149-1) may be provided on the outer surface of the nut pulley (143).

[0314] On the outer surface of the first motor pulley (142a), a first motor pulley tooth (142-1) coupled with an inner belt tooth (149-1) may be provided, and on the outer surface of the second motor pulley (142b), a second motor pulley (142b) coupled with an inner belt tooth (149-1) may be provided.

[0315] Here, the number of the first motor pulley reach (142-1) and the second motor pulley reach (142-2) may be formed differently.

[0316] That is, the first motor pulley reach (142-1) and the second motor pulley reach (142-2) are formed with different pitch circle diameters and the number of teeth.

[0317] Additionally, the first motor (145) may be equipped with a first motor sensor (145s) that detects the rotational position of the first motor (145) and transmits it to the electronic control unit (110), and the second motor (147) may be equipped with a second motor sensor (147s) that detects the rotational position of the second motor (147) and transmits it to the electronic control unit (110).

[0318] The electronic control unit (110) can control the output value transmitted to the first motor and the second motor (147) by calculating the movement position of the rack bar (130) based on the first position value transmitted from the first motor sensor (145s) and the second position value transmitted from the second motor sensor (147s).

[0319] As explained above, according to the embodiments, in both the steer-by-wire steering system and the general steering system, the moving position of the rack bar can be accurately detected, and thereby the electronic control unit can accurately control the motor, thereby improving the steering stability of the vehicle.

[0320] In addition, according to the embodiments, the effect of making it easier to adjust the belt tension is achieved by adjusting only the position of the second motor pulley.

[0321] The foregoing description is merely an illustrative explanation of the technical concept of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations within the scope of the essential characteristics of the technical concept. Furthermore, since these embodiments are intended to explain, not limit, the scope of the technical concept of the present disclosure is not limited by these embodiments. The scope of protection of the present disclosure shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present disclosure.

Claims

Claim 1 An automobile steering device comprising: a ball nut coupled via a rack bar and a ball and rotating to move the rack bar in the axial direction; a nut pulley provided on the outer surface of the ball nut; a first motor pulley provided on a first motor and coupled to the nut pulley by a belt; a second motor pulley provided on a second motor and coupled to the belt between the nut pulley and the first motor pulley; and an electronic control device that controls an output value transmitted to the first motor and the second motor using an electrical signal as an input value. Claim 2 An automobile steering device according to claim 1, wherein the inner circumferential surface of the belt is provided with an inner circumferential belt tooth and the outer circumferential surface is provided with an outer circumferential belt tooth, the outer circumferential surface of the nut pulley is provided with a nut pulley tooth that is coupled to the inner circumferential belt tooth, the outer circumferential surface of the first motor pulley is provided with a first motor pulley tooth that is coupled to the inner circumferential belt tooth, and the outer circumferential surface of the second motor pulley is provided with a second motor pulley tooth that is coupled to the outer circumferential belt tooth. Claim 3 In claim 2, an automobile steering device in which the number of the first motor pulley reach and the second motor pulley reach are formed differently. Claim 4 In claim 3, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 5 An automobile steering device according to claim 2, wherein the number of the first motor pulley and the second motor pulley are the same, and the pitches of the inner belt teeth and the outer belt teeth are formed differently. Claim 6 In claim 5, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 7 An automobile steering device according to claim 2, wherein the number of the first motor pulley and the second motor pulley are formed differently, and the pitch of the inner belt tooth and the outer belt tooth is formed differently. Claim 8 In claim 7, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 9 An automobile steering device according to claim 1, wherein the inner circumferential surface of the belt is provided with an inner circumferential belt tooth and the outer circumferential surface is provided with an outer circumferential belt tooth, the outer circumferential surface of the nut pulley is provided with a nut pulley tooth that is coupled to the inner circumferential belt tooth, the outer circumferential surface of the first motor pulley is provided with a first motor pulley tooth that is coupled to the inner circumferential belt tooth, and the outer circumferential surface of the second motor pulley is provided with a second motor pulley tooth that is coupled to the inner circumferential belt tooth. Claim 10 In claim 9, an automobile steering device in which the number of the first motor pulley reach and the second motor pulley reach are formed differently. Claim 11 In claim 10, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 12 An automobile steering device comprising: a ball nut coupled via a rack bar and a ball to rotate and move the rack bar in the axial direction; a nut pulley provided on the outer surface of the ball nut; a first motor pulley provided on a first motor and connected to the nut pulley by a belt; a second motor pulley provided on a second motor and coupled to the belt between the nut pulley and the first motor pulley; an electronic control device that controls an output value transmitted to the first motor and the second motor using an electrical signal as an input value; and a pinion shaft, one end of which is coupled to a steering shaft coupled to a steering wheel and the other end of which supports and is coupled to one side of the rack bar. Claim 13 In claim 12, an inner belt tooth is provided on the inner surface of the belt and an outer belt tooth is provided on the outer surface, a nut pulley tooth that is coupled to the inner belt tooth is provided on the outer surface of the nut pulley, a first motor pulley tooth that is coupled to the inner belt tooth is provided on the outer surface of the first motor pulley, and a second motor pulley tooth that is coupled to the outer belt tooth is provided on the outer surface of the second motor pulley. Claim 14 In claim 13, an automobile steering device in which the number of the first motor pulley reach and the second motor pulley reach are formed differently. Claim 15 In claim 14, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 16 In claim 13, an automobile steering device in which the number of the first motor pulley and the second motor pulley are the same and the pitches of the inner belt and the outer belt are formed differently. Claim 17 In claim 16, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 18 In claim 13, an automobile steering device in which the number of the first motor pulley and the second motor pulley are formed differently, and the pitch of the inner belt tooth and the outer belt tooth is formed differently. Claim 19 In claim 18, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor. Claim 20 In claim 12, an inner belt tooth is provided on the inner surface of the belt and an outer belt tooth is provided on the outer surface, a nut pulley tooth that is coupled to the inner belt tooth is provided on the outer surface of the nut pulley, a first motor pulley tooth that is coupled to the inner belt tooth is provided on the outer surface of the first motor pulley, and a second motor pulley tooth that is coupled to the inner belt tooth is provided on the outer surface of the second motor pulley. Claim 21 In claim 20, an automobile steering device in which the number of the first motor pulley reach and the second motor pulley reach are formed differently. Claim 22 In claim 21, the first motor is equipped with a first motor sensor that detects the rotational position of the first motor and transmits it to the electronic control unit, and the second motor is equipped with a second motor sensor that detects the rotational position of the second motor and transmits it to the electronic control unit, and the electronic control unit controls the output value transmitted to the first motor and the second motor by calculating the movement position of the rack bar based on a first position value transmitted from the first motor sensor and a second position value transmitted from the second motor sensor.

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