STEER-BY-WIRE steering system

Abstract

Steering system, which includes: a first pulley (131) coupled to a steering shaft (103); a second pulley (135) which is coupled to the first pulley (131) via a belt (133) and is coupled to a shaft (120a) of a reaction motor (120); an engagement element (140) that is coupled to the shaft (120a) of the reaction motor (120) and has engagement recesses (140a) formed in an outer surface of the engagement element (140); several anti-rotation elements (141a, 141b), each anti-rotation element (141a, 141b) comprising a part movably coupled via a cardan shaft (149) to a housing (127) covering at least a section of the first and second pulleys (131, 135), and a further part comprising engagement projections (141c) that can engage with the engagement recesses (140a) of the engagement element (140), each anti-rotation element (141a, 141b) being capable of engaging with different sections of the outer surface of the engagement element (140); and a cam element (143) arranged between the anti-rotation elements (141a, 141b) is coupled to a shaft (125a) of a drive motor (125) and is designed to be rotatable in order to move the anti-rotation elements (141a, 141b), wherein the steering device further comprises elastic elements (145) coupled to an inner surface of the housing (127), wherein the elastic elements (145) elastically support the elements (141a, 141b) that prevent rotation, wherein: the cam element (143) has a trapezoidal shape comprising a long side and a short side that are parallel to each other; and at least one end of the long side of the cam element (143), when it is in contact with at least one of the rotation-preventing elements (141a, 141b), moves at least one of the rotation-preventing elements (141a, 141b), so that at least one of the elastic elements (145) is compressed and at least one of the engagement projections (141c) is released from engagement with the engagement recesses (140a).

Description

BACKGROUND 1. Technical field

[0001] Some embodiments of the present disclosure may relate to a steer-by-wire steering device. In particular, certain exemplary embodiments of the present disclosure may relate to a steer-by-wire steering device which is capable of preventing the rotation of a steering shaft when a driver generates a steering torque that is greater than a reaction torque of a reaction motor in the steering shaft. 2. Description of the state of the art

[0002] In general, power steering was developed and used for a vehicle's steering system to achieve comfortable driving by assisting the driver's steering effort; examples of power steering include hydraulic power steering, which uses hydraulic pressure; electro-hydraulic power steering, which uses both hydraulic pressure and electrical power from a motor; and electric power steering, which uses only electrical power from a motor.

[0003] More recently, a steer-by-wire (SBW) steering system has been developed and used, in which the steering of the vehicle is carried out using an electric motor, such as a motor, which eliminates a mechanical connecting device, such as a steering column, between the steering wheel and a wheel, a universal joint or a pinion shaft.

[0004] However, since there is no mechanical connection between a steering shaft and the wheel in such a steer-by-wire steering system, the rotation of the driver's steering wheel is not limited, so the driver's steering feel may be impaired.

[0005] This means that when the rotation of the wheels reaches a maximum point (when, in a state-of-the-art steering system, the steering wheel or the wheels are fully turned) or when the wheels hit a curb of a road and cannot be turned any further, it is necessary not to turn the steering shaft any further and to transmit appropriate information to the driver.

[0006] DE 603 ​​03 081 T2 discloses a conventional steering device. In DE 603 ​​03 081 T2, elements preventing rotation are prevented by springs from coming into contact with an engagement element. When engagement is to be activated, an electric rotary actuator rotates the elements preventing rotation against the spring force, and the electric rotary actuator maintains a constant force against the spring force during the active engagement position.

[0007] DE 103 06 100 A1 discloses another conventional steering device. DE 103 06 100 A1 discloses a cam element which is used to press anti-rotation elements against an engagement element by means of a rotational force. When the rotational force on the cam element is released, the anti-rotation elements disengage from the engagement element. SUMMARY

[0008] Against this background, the present disclosure aims to provide a steer-by-wire steering device capable of preventing the rotation of a steering shaft when a driver generates a steering torque greater than the reaction torque of a reaction motor in the steering shaft.

[0009] It should be noted that the subject matter of this disclosure is not limited to the subject matter mentioned above, and other subject matter of this disclosure will be understandable to those skilled in the art from the following description.

[0010] To solve the above problem, one embodiment provides a steer-by-wire steering device comprising: a first pulley coupled to a steering shaft, a second pulley coupled to the first pulley via a belt and coupled to a shaft of a reaction motor, an engagement element coupled to the shaft of the reaction motor and having engagement recesses formed in an outer circumferential surface of the second pulley, a pair of anti-rotation elements, one end of each of which is coupled via a driveshaft for rotation to a housing in which the first pulley and the second pulley are embedded, and the other end of which has engagement projections supported in the engagement recesses, wherein the pair of anti-rotation elements is supported in engagement recesses on one side and the other side of the outer circumferential surface of the engagement element.and a cam element arranged between the ends of a pair of anti-rotation elements, is rotated, being coupled to a shaft of a drive motor, and each of the anti-rotation elements rotates about the driveshaft. The steering device further comprises elastic elements coupled to an inner surface of the housing, the elastic elements elastically supporting the anti-rotation elements. The cam element has a trapezoidal shape comprising a long side and a short side parallel to each other; and at least one end of the long side of the cam element, when in contact with at least one of the anti-rotation elements, moves at least one of the anti-rotation elements, such that at least one of the elastic elements is compressed and at least one of the engagement projections is disengaged from the engagement recesses.

[0011] One embodiment provides a steer-by-wire steering device comprising: a first element coupled to one side of a steering shaft and a shaft of a reaction motor, having mounting recesses formed in an axial direction on an outer circumferential surface of one end of the first element; a second element, having mounting projections corresponding to the mounting recesses, coupled to an outer surface of the first element, and having first support recesses formed in a circumferential direction and spaced apart from one another on one end of the second element; a third element coupled to the other side of the steering shaft and the shaft of the reaction motor, having second support recesses in positions corresponding to the first support recesses; and a ball element.which is supported in and inserted into the first and second support recesses, and a ring-shaped anti-rotation element which is attached to a housing in which the steering shaft is embedded, has engagement recesses formed in an inner circumferential surface of it in the axial direction, and is coupled to outer circumferential surfaces of the second and third elements.

[0012] According to the present embodiments, in a steer-by-wire steering system, if a driver generates a steering torque that is greater than a reaction torque of a reaction motor in a steering shaft, rotation of the steering shaft can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and further aspects and advantages of the present disclosure will become even clearer from the following detailed description in conjunction with the accompanying drawings, wherein: Fig. Figure 1 is a schematic representation of a steer-by-wire steering system according to the present embodiments; Fig. Figure 2 is a perspective view of part of the steer-by-wire steering system according to the present embodiments; Fig. Figures 3 to 7 are front views of a part of the steer-by-wire steering system according to the present embodiments; Fig. Figure 8 is a schematic representation of a steer-by-wire steering system according to other embodiments; Fig. Figure 9 is a perspective view of part of the steer-by-wire steering system according to other embodiments; Fig. Figure 10 is an expanded perspective view of part of the steer-by-wire steering system according to other embodiments; Fig. Figure 11 is a sectional view of a part of the steer-by-wire steering system according to other embodiments; and Fig. Figures 12 to 14 are front views of a part of the steer-by-wire steering system according to other embodiments. DETAILED DESCRIPTION OF EXAMPLE EXECUTIONS

[0014] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. When adding reference numerals to elements in each drawing, the same elements are designated with the same reference numerals whenever possible, even if the elements are shown in different drawings. Furthermore, the following description of the present disclosure omits a detailed description of known functions and configurations incorporated herein if it is determined that such a description might render the subject matter of the present disclosure rather unclear.

[0015] Furthermore, when describing elements of the present embodiments, terms such as "first", "second", A, B, (a) and (b) may be used. These terms are used solely to distinguish one element from another, and the nature, order, or sequence of a corresponding element is not restricted by these terms. When it is described that an element is "connected", "coupled", or "joined" to another element, this is to be understood as meaning that the element may be directly connected or joined to another element, but that a further element may also be "connected", "coupled", or "joined" to the two elements.

[0016] It will initially be on Fig. Reference is made to numbers 1 to 7; A steer-by-wire steering device according to the present embodiments comprises: a first pulley 131 coupled to a steering shaft 103, a second pulley 135 coupled to the first pulley 131 via a belt 133 and coupled to a shaft 120a of a reaction motor 120, an engagement element 140 coupled to the shaft 120a of the reaction motor 120 and having engagement recesses 140a formed in an outer circumferential surface of the element, and a pair of anti-rotation elements 141a and 141b, each having one end attached via a driveshaft 149 for rotation to a housing 127 in which the first pulley 131 and the second pulley 135 are embedded, and another end in which engagement projections 141c are formed. which are supported in the intervention recesses 140a,wherein the pair of anti-rotation elements 141a and 141b is supported in the engagement recesses 140a on both sides of the outer circumferential surface of the engagement element 140, and a cam element 143, which is arranged between the one ends of the anti-rotation elements 141a and 141b, is rotated, being coupled to a shaft 125a of a drive motor 125, and each of the anti-rotation elements 141a and 141b rotates about the cardan shaft 149.

[0017] In the steer-by-wire steering device according to the present embodiments, an angle sensor 105 and a torque sensor 107 are coupled to one side of the steering shaft 103, which is connected to a steering wheel 101, and when a driver operates the steering wheel 101, the angle sensor 105 and the torque sensor 107, which detect the operation by the driver, transmit electrical signals to an electronic control unit (ECU) 110, so that the reaction motor 120 and a pinion shaft motor 130 can operate.

[0018] The ECU 110 controls the reaction motor 120 and the pinion shaft motor 130 using electrical signals transmitted by the angle sensor 105 and the torque sensor 107, and electrical signals transmitted by various sensors attached to a car.

[0019] The pinion shaft motor 130 moves a rack 111, which is connected to a pinion shaft 113, to steer the wheels 119 mounted on both sides using a tie rod 115 and a steering knuckle 117, and the reaction motor 120 generates a steering reaction sensation in the opposite direction when the driver operates the steering wheel 101, or performs steering of the steering shaft 103 when autonomous driving is carried out.

[0020] However, for the sake of simplicity, the drawings of the present embodiments show the angle sensor 105 and the torque sensor 107 on the steering shaft 103. However, it is obvious that an engine position sensor, various types of radar, and a camera image sensor for transmitting steering information to the ECU 110 could also be provided, and a detailed description of these is omitted below.

[0021] Since the steering shaft 103 and the pinion shaft 113 are not mechanically connected in the steer-by-wire steering system, the rotation of the steering wheel 101 by the driver is not limited, so mechanical limits are required by which the rotation is stopped at an arbitrarily fixed angle.

[0022] This means that when the rotation of the wheels 119 reaches a maximum point (when, in a state-of-the-art steering system, the steering wheel 101 or the wheels 119 are in a fully turned position), or when the wheels 119 encounter a curb and cannot be turned any further, the reaction motor 120 outputs a reaction torque up to its maximum. This prevents the steering shaft 103 from rotating, thus preventing it from transmitting this information to the driver.

[0023] A drive motor 125 is provided, which is mechanically connected to the steering shaft 103 to prevent rotation of the steering shaft 103. If a steering torque is generated which is greater than or equal to a maximum reaction torque of the reaction motor 120, the anti-rotation elements 141a and 141b cause the rotation of the steering shaft 103 to be stopped.

[0024] First, the steering shaft 103, which is coupled to the steering wheel 101, is provided in a steering column 123, which is attached to a body of the car, and the reaction motor 120 for generating a steering reaction feeling at the steering shaft 103, as well as the drive motor 125, which causes the rotation of the steering shaft 103 to stop when a steering torque is generated in the steering shaft 103 which is greater than or equal to the maximum reaction torque of the reaction motor 120, are provided via the housing 127 on both sides of the steering column 123.

[0025] The first pulley 131 is coupled to the steering shaft 103, and the second pulley 135 is coupled to the shaft 120a of the reaction motor 120, and the first pulley 131 and the second pulley 135 are connected to each other via the belt 133.

[0026] Thus, when the driver operates the steering wheel 101, the ECU 110 activates the reaction motor 120 based on signal values ​​detected by the torque sensor 107 and the angle sensor 105, in order to generate a reaction torque in a direction opposite to the direction of rotation of the steering shaft 103.

[0027] Furthermore, the engagement element 140, in whose outer circumferential surface the engagement recesses 140a are formed one behind the other, is coupled to the shaft 120a of the reaction motor 120 and is rotated together with the shaft 120a of the reaction motor 120, and the pair of anti-rotation elements 141a and 141b is provided, which prevent rotation of the engagement element 140.

[0028] Here, the one ends of the anti-rotation elements 141a and 141b are coupled to the housing 127 via the cardan shaft 149, in which the first pulley 131 and the second pulley 135 are embedded, and the engagement projections 141c, which are supported in the engagement recesses 140a of the engagement element 140, are formed at the other ends of the anti-rotation elements 141a and 141b.

[0029] Furthermore, the other ends of the elements 141a and 141b, which prevent rotation, are supported in the engagement recesses 140a on one side and the other side of the outer circumferential surface of the engagement element 140, respectively.

[0030] The cam element 143 for rotating each of the rotation-preventing elements 141a and 141b by means of the respective drive shaft 149 is arranged at one end of the rotation-preventing elements 141a and 141b. The cam element 143 is coupled to the shaft 125a of the drive motor 125 and is rotated.

[0031] Furthermore, an elastic element 145 is coupled to an inner circumferential surface of the housing 127 for elastically supporting the anti-rotation elements 141a and 141b using the engagement element 140. Therefore, as long as the cam element 143 does not spread the anti-rotation elements 141a and 141b to both sides, the cam element 143 is supported inwards by means of the drive shaft 149.

[0032] Support recesses 147 are formed in the inner circumferential surface of the housing 127, into which the elastic element 145 is inserted and supported. The support recesses 147 can be formed in a projecting end 148, which protrudes from the inner circumferential surface of the housing 127.

[0033] The cam element 143 can be formed in a trapezoidal shape with a predetermined thickness, and when the two ends of a long side 143a are connected by two opposite and parallel sides of the trapezoidal shape, each end of which is formed by one of the two anti-rotation elements 141a and 141b, the two elements 141a and 141b are spread apart to both sides by means of the drive shaft 149. In this case, the elastic element 145 is compressed, and the engagement projections 141c are moved into positions away from the engagement recesses 140a.

[0034] Furthermore, if a short side 143b of two opposing and parallel sides of the cam element 143 is arranged at one end of the two anti-rotation elements 141a and 141b, as shown in Fig. 5 shown, the elastic element 145 relaxes, and the engagement projections 141c are moved into positions in which the engagement projections engage in the engagement recesses 140a.

[0035] That is, when the two ends of the long side 143a of the cam element 143 are supported by the anti-rotation elements 141a and 141b, the elastic element 145 is compressed, and the engagement projections 141c are moved into positions away from the engagement recesses 140a, and when the two ends of the long side 143a of the cam element 143 are not supported by the anti-rotation elements 141a and 141b, the elastic element 145 is relaxed, and the engagement projections 141c engage in the engagement recesses 140a.

[0036] Therefore, when the engagement projections 141c are supported in the engagement recesses 140a, rotation of the steering shaft 103 is prevented, and when the engagement projections 141c are moved into positions away from the engagement recesses 140a, rotation of the steering shaft 103 is possible.

[0037] The steer-by-wire steering device according to the present embodiments can further comprise a torque sensor 107 for measuring a value of the steering torque generated in the steering shaft 103, and an electronic control unit (ECU) 110, which calculates a value of the reaction torque of the steering shaft 103 based on the value of the steering torque measured by the torque sensor 107, transmits the calculated value of the reaction torque to the reaction motor 120 and compares the value of the steering torque with a set maximum value of the reaction torque to determine whether the drive motor 125 should be started.

[0038] In this case, if the value of the steering torque is less than the set maximum value of the reaction torque, the ECU 110 starts the drive motor 125, so that the two ends of the long side 143a are supported by two opposite and parallel sides of the cam element 143 by one end of each of the anti-rotation elements 141a and 141b and the engagement projections 141c are moved into positions that are away from the engagement recesses 140a.

[0039] Furthermore, if the value of the steering torque is greater than the set maximum value of the reaction torque, the ECU 110 starts the drive motor 125, so that one end of the long side 143a of two opposite and parallel sides of the cam element 143 is separated from one end of the anti-rotation element 141b (see Fig. 6) or 141a (see Fig. 7) is supported to brace in one direction towards a reaction moment, and thus only the element 141b preventing rotation (see Fig. 6) or 141a (see Fig. 7) to be moved in the direction of the reaction moment to a position that is away from the engagement recesses 140a.

[0040] This means that if the value of the steering torque in one direction, for example in the direction of turning left, is greater than the maximum value of the reaction torque, only a rotation of the steering shaft 103 in the direction of turning left is prevented, and a rotation of the steering shaft 103 in the direction of turning right, opposite to the direction of turning left, is possible.

[0041] This will now be demonstrated using Fig. 6 and Fig. 7 described. Fig. Figure 6 first illustrates the case in which the value of the steering torque in the direction of turning left is greater than the maximum value of the reaction torque. This case means that a rotation of the engagement element 140 to the left, which corresponds to a counterclockwise direction in the drawings, is not possible, while a rotation of the engagement element 140 to the right, which corresponds to a clockwise direction in the drawings, is possible. The fact that the rotation of the engagement element 140 to the left is not possible means that a rotation of the steering shaft 103, which is connected to the shaft 120a of the reaction motor 120 via the first pulley 131 and the second pulley 135, to the left is also not possible.

[0042] That means that Fig. Figure 6 illustrates the case in which the driver generates a steering torque in the direction of turning to the left, that the reaction torque is generated in the direction of a rotation to the right, which in the drawings is the clockwise direction, and only the element 141b preventing rotation (see Fig. 6) to support a reaction moment direction, so that the rotation of the engagement element 140 to the right is possible, is moved into a position that is away from the engagement recesses 140a.

[0043] In contrast, since Fig. Figure 7 illustrates the case where the value of the steering torque in the direction of turning to the right is greater than the maximum value of the reaction torque. In this case, a rotation of the engagement element 140 to the right, which corresponds to a clockwise direction in the drawings, is not possible, while a rotation of the engagement element 140 to the left, which corresponds to a counterclockwise direction in the drawings, is possible. The fact that the rotation of the engagement element 140 to the right is not possible means that a rotation of the steering shaft 103, which is connected to the shaft 120a of the reaction motor 120 via the first pulley 131 and the second pulley 135, to the right is also not possible.

[0044] This involves, since Fig. Figure 7 illustrates the case in which the driver generates a steering torque in the direction of turning to the right, the reaction torque is generated in the direction of a rotation to the left, which in the drawings is the counterclockwise direction, and only the element 141a preventing rotation (see Fig. 7) to support the direction of the reaction moment, so that the rotation of the engagement element 140 to the left is possible, is moved into a position that is away from the engagement recesses 140a.

[0045] This means that, depending on whether the ECU 110 actuates the drive motor 125 in such a way that it rotates the cam element 143 in the respective direction, only a rotation of the steering shaft 103 in one direction is not possible.

[0046] It will now be on Fig. Reference is made to 8 to 14; A steer-by-wire steering device according to the present embodiments comprises: a first element 241, which is coupled to one side of a steering shaft 203 and a shaft 223 of a reaction motor and has mounting recesses 241a formed in an outer circumferential surface of one end of it located on one side in an axial direction; a second element 243, which has mounting projections 243a corresponding to the mounting recesses 241a in it, is coupled to an outer surface of the first element 241 and has first support recesses 243b formed in one end of the second element 243 located on one side in a circumferential direction and spaced apart from each other; a third element 245, which is coupled to the other side of the steering shaft 203 and the shaft 223 of the reaction motor and has second support recesses 245b at positionscorresponding to the first support recesses 243b, a spherical element 251, which is supported in and inserted into the first support recesses 243b and the second support recesses 245b, and an element 247 formed in a ring shape, preventing rotation, which is attached to a housing in which the steering shaft 203 is embedded, has engagement recesses 247a formed in an inner circumferential surface of it in the axial direction, and is coupled to outer circumferential surfaces of the second element 243 and the third element 245.

[0047] In the steer-by-wire steering device according to the present embodiments, an angle sensor 205 and a torque sensor 207 are coupled to one side of the steering shaft 203, which is connected to a steering wheel 201, and when a driver operates the steering wheel 201, the angle sensor 205 and the torque sensor 207, which detect the operation by the driver, transmit electrical signals to an ECU 210, so that a reaction motor 220 and a pinion shaft motor 230 can operate.

[0048] The ECU 210 controls the reaction motor 220 and the pinion shaft motor 230 using the electrical signals transmitted by the angle sensor 205 and the torque sensor 207, and electrical signals transmitted by various sensors attached to the car.

[0049] The pinion shaft motor 230 moves a rack 211, which is connected to a pinion shaft 213, to steer the wheels 219 mounted on both sides using a tie rod 215 and a steering knuckle 217. The reaction motor 220 generates a steering response sensation in the opposite direction when the driver operates the steering wheel 201, or performs steering of the steering shaft 203 when autonomous driving is performed, and the shaft 223 of the reaction motor is coaxially connected to the steering shaft 203.

[0050] The first element 241 is coupled to one side of the steering shaft 203 and the shaft 223 of the reaction motor to prevent rotation of the steering shaft 203, and the third element 245 is coupled to the other side of the same, and the second element 243 and the ball element 251 are coupled between the first element 241 and the third element 245. If a steering shaft torque greater than or equal to a reaction torque is generated in the shaft 223 of the reaction motor, the ball element 251 is supported in the engagement recesses 247a of the anti-rotation element 247, thus stopping rotation of the steering shaft 203.

[0051] To simplify the explanation, an example is shown in which the first element 241 is coupled to the steering shaft 203 and the third element 245 is coupled to the shaft 223 of the reaction motor, and this will now be described.

[0052] The axially formed fastening recesses 241a are formed in an outer circumferential surface of an end of the first element 241 located on one side, which is coupled to the steering shaft 203, and the fastening projections 243a of the second element 243 are coupled to the fastening recesses 241a, so that the first element 241 and the second element 243 can be rotated as a single body.

[0053] The second element 243 is formed in a ring shape, and the fastening projections 243a corresponding to the fastening recesses 241a of the first element 241 are formed axially in an inner circumferential surface of the second element 243 and coupled to the outside of the first element 241, and the first support recesses 243b are formed in an end of the second element 243 located on one side and are spaced apart from each other in the circumferential direction.

[0054] The second support recesses 245b are formed at positions of the third element 245 coupled to the shaft 223 of the reaction motor, which correspond to positions of the first support recesses 243b of the second element 243.

[0055] Here, the first support recesses 243b are formed in a conical shape, which is in contact with the spherical element 251 along a circular line, as shown in Fig. 10 and Fig. 11 shown.

[0056] Both sides of the second support recesses 245b are inclined, so that their widths gradually increase from a surface facing an end of the second element 243 located on one side to a radially outer circumferential surface of the second element 243, and the spherical element 251 is supported in and inserted into the first support recesses 243b of the second element 243 and the second support recesses 245b of the third element 245.

[0057] The element 247, which prevents rotation and is formed in a ring shape and has the engagement recesses 247a formed in the inner circumferential surface of the same in the axial direction, is coupled to the outer circumferential surfaces of the second element 243 and the third element 245.

[0058] Although not shown in the drawings, the anti-rotation element 247 is attached to the housing in which the steering shaft 203 is embedded, or to a car body, and regardless of rotation of the first element 241, the second element 243 and the third element 245, it does not rotate and remains stationary.

[0059] The first element 241 has an extension part 241b, which is formed at one end of the fastening recesses 241a located on one side by means of a middle part in which the fastening recesses 241a are formed, and extends in the axial direction, and a large diameter part 241c, which is formed at the other end of the fastening recesses 241a located on the other side and has an increased diameter.

[0060] An elastic element 249 is provided between the large diameter part 241c of the first element 241 and the second element 243 and exerts an elastic force in the axial direction in order to support the spherical element 251 by applying the elastic force of the elastic element 249.

[0061] Furthermore, a coupling part 241d with a screw part located therein is provided on an inner circumferential surface of the extension part 241b of the first element 241, and the third element 245 has a through hole 245a in its interior, so that a body part 248a of a fastening element 248 is coupled to the coupling part 241d of the first element 241 through the through hole 245a.

[0062] Furthermore, an engagement step 245c is formed on one side of the through hole 245a, so that a head part 248a of the fastening element 248 is supported by the engagement step 245c and deflection of the fastening element 248 is prevented.

[0063] Since the fastening element 248 couples the first element 241 with the third element 245, it thereby establishes a distance between them, so that the elastic force of the elastic element 249 can be adjusted with a fastening size of the fastening element 248.

[0064] Thus, the first element 241, the second element 243 and the third element 245 are assembled so that they are functional on the same axis, so that the elastic force of the elastic element 249 is set.

[0065] Here, two or more support recesses 243b of the second element 243 and two or more support recesses 245b of the third element 245 are spaced apart from each other in the circumferential direction. The drawings show three first support recesses 243b and three second support recesses 245b. In this case, the first support recesses 243b and the second support recesses 245b are provided at equal intervals in the circumferential direction, so that the spherical element 251 is held with the same supporting force in the axial direction.

[0066] In the steer-by-wire steering device according to the present embodiments, when the steering angle of the wheels 219 reaches a maximum point or when the wheels 219 hit a curb of a road and cannot be turned further, as described above, rotation of the steering shaft 203 is prevented.

[0067] That is, in a general steering state, the elastic element 249 is held in a state compressed by a predetermined amount due to the fastening element 248, and a torque is transmitted from the steering shaft 203 through the first element 241, the second element 243 and the third element 245 to the shaft 223 of the reaction motor.

[0068] In this case, the spherical element 251 is arranged only in the first support recesses 243b and the second support recesses 245b, as shown in Fig. 12 and Fig.Figure 13 shows that if rotation of the steering shaft 203 is to be prevented, as described above, i.e., if an excessively high torque, greater than or equal to the reaction torque of the shaft 223 of the reaction motor, is transmitted from the steering shaft 203, then, as a result of a rotational force of the second element 243, the ball element 251 is moved outwards in a radial direction along both sides of the second support recesses 245b and is supported in the engagement recesses 247a of the anti-rotation element 247, thus limiting further rotation.

[0069] That is, if the torque transmitted from the steering shaft 203 to the second element 243 is too large, the spherical element 251 is moved outwards in the radial direction along both inclined surfaces of the second support recesses 245b as a result of a force component of a force acting in the circumferential direction, and at the same time, if the spherical element 251 is moved outwards from a central part of the first support recesses 243b, the second element 243 is moved in the axial direction by a difference equal to the amount of the axial movement of the spherical element 251, and the elastic element 249 is further compressed.

[0070] In contrast, when the torque is reduced, the second element 243 is moved in the axial direction as a result of a restoring force of the elastic element 249, and the spherical element 251 is moved to the middle part of the first support recesses 243b, and at the same time the spherical element 251 is moved to a position away from the engagement recesses 247a, and is moved back to the second support recesses 245b.

[0071] Thus, when the elastic force of the elastic element 249 is set according to a design target value and a rotational force is transmitted which is greater than or equal to a predetermined torque value, the second element 243 is rotated and moved in the axial direction as a result of the elastic force of the elastic element 249, and a radial movement of the ball element 251 takes place, so that a rotation of the steering shaft 203 can be prevented.

[0072] As described above, according to the present embodiments, if a driver generates a steering torque that is greater than a reaction torque of a reaction motor in a steering shaft in a steer-by-wire steering device, rotation of the steering shaft can be prevented.

[0073] As described above, although all elements comprising the present embodiments are described as being connected as a unit or functioning as coupled together, the present embodiments are not necessarily limited to these embodiments. That is to say, if all elements are within the scope of the purposes of the embodiments, all elements can also function when selectively connected to form one or more units.

Claims

[1] Steering device comprising: a first pulley (131) coupled to a steering shaft (103); a second pulley (135) coupled to the first pulley (131) via a belt (133) and coupled to a shaft (120a) of a reaction motor (120); an engagement member (140) coupled to the shaft (120a) of the reaction motor (120) and having engagement recesses (140a) formed in an outer surface of the engagement member (140); a plurality of rotation-preventing members (141a, 141b), each of the rotation-preventing members (141a, 141b) comprising a part movably coupled via a hinge shaft (149) to a housing (127) covering at least a portion of the first and second pulleys (131, 135), and another part comprising engaging projections (141c) engageable with the engaging recesses (140a) of the engaging member (140), each of the rotation-preventing members (141a, 141b) engageable with different portions of the outer surface of the engaging member (140); and a cam element (143) arranged between the rotation-preventing elements (141a, 141b), coupled to a shaft (125a) of a drive motor (125) and designed to be rotated to move the rotation-preventing elements (141a, 141b), wherein the steering device further comprises elastic elements (145) coupled to an inner surface of the housing (127), the elastic elements (145) elastically supporting the rotation-preventing elements (141a, 141b), wherein: the cam element (143) has a trapezoidal shape comprising a long side and a short side which are parallel to each other; and at least one end of the long side of the cam member (143), when in contact with at least one of the rotation preventing members (141a, 141b), moves the at least one of the rotation preventing members (141a, 141b) so that at least one of the elastic members (145) is compressed and at least one of the engaging projections (141c) is released from engagement with the engaging recesses (140a). [2] A steering device according to claim 1, wherein support recesses are formed in the inner surface of the housing and the elastic members are inserted into the support recesses. [3] A steering device according to claim 1, wherein when the short side of the cam member moves toward the one part of the rotation preventing members movably coupled to the housing, the elastic member is relaxed and the engaging projections are engaged with the engaging recesses. [4] Steering device according to claim 1, which further comprises: a torque sensor configured to measure a steering torque generated by the steering shaft; and an electronic control unit (ECU) configured to calculate a steering shaft reaction torque value based on the steering torque measured by the torque sensor, output the calculated reaction torque value to the reaction motor, and compare the steering torque with a set maximum reaction torque value to determine whether to start the drive motor. [5] A steering device according to claim 4, wherein the ECU is configured to, when the steering torque measured by the torque sensor is less than the maximum value of the reaction torque, start the drive motor so that the two ends of the long side of the cam member come into contact with each of the rotation preventing members. [6] A steering device according to claim 4, wherein the ECU is configured to, when the value of the steering torque is greater than the maximum value of the reaction torque, start the drive motor so that one end of the long side of the cam member comes into contact with one of the rotation preventing members. [7] Steering device comprising: a first member (241) coupled to a steering shaft (203), wherein mounting recesses (241a) are formed in at least a portion of an outer surface of the first member (241) in an axial direction; a second member (243) having fastening projections (243a) corresponding to the fastening recesses (241a) of the first member (241), wherein first support recesses (243b) are formed in one side of the second member (243) and are spaced apart from each other; a third member (245) having second support recesses (245b) at positions corresponding to the first support recesses (243b); a ball element (251) inserted into the first support recesses (243b) of the second element (243) and the second support recesses (245b) of the third element (245); and a rotation-preventing member (247) having a ring shape, the rotation-preventing member (247) being fixed to a housing of the steering shaft (203), an inner surface of the rotation-preventing member (247) including engagement recesses (247a), and the rotation-preventing member (247) being coupled to outer surfaces of the second and third members (243, 245). [8] A steering device according to claim 7, wherein the second member has a ring shape and the fastening projections are formed in an inner surface of the second member. [9] Steering device according to claim 7, wherein the first support recesses have a conical shape which is in contact with the ball element along a circular line. [10] A steering device according to claim 7, wherein the second support recesses of the third member are open outwardly toward the rotation preventing member. [11] A steering device according to claim 10, wherein the second support recesses comprise inclined sides so that the widths of the second support recesses gradually increase outwardly. [12] A steering device according to claim 7, wherein the first member has an extension part extending from a central part of one side of the mounting recess in an axial direction. [13] The steering device according to claim 12, wherein the first member includes a large diameter part formed on another side of the mounting recess, the large diameter part having a larger diameter than a part of the first member in which the mounting recess is formed. [14] A steering device according to claim 13, further comprising an elastic member exerting an elastic force in the axial direction and provided between the second member and the large diameter part of the first member. [15] The steering device according to claim 12, wherein the extension part of the first member comprises a coupling part having a screw part formed on an inner surface of the coupling part. [16] Steering device according to claim 15, wherein: the third element has a through hole formed in the third element, and the steering device further comprises a fastening element coupled to the coupling part of the first element via the through hole. [17] The steering device according to claim 16, wherein an engagement step is formed on a side of the through hole of the third member so that a head portion of the fastening member is supported by the engagement step. [18] Steering device according to claim 7, wherein the first support recesses and the second support recesses are spaced apart from each other in a circumferential direction.

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