JP2007062412A - Steering device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device of a vehicle enabling the miniaturization of a steering actuator. <P>SOLUTION: This steering device is provided with the steering actuator 15 for driving a steering link in the axial direction. The steering device is provided with a ball screw mechanism provided with a screw shaft 14 and two nut shafts 21 and 22, a first hollow motor 23 concentrically passed and arranged with the screw shaft 14 to transmit rotation to the one nut shaft 21, a second hollow motor 24 having an eccentric axis Q parallel to an axis P of the screw shaft 14 and passed and arranged with the screw shaft 14, and a deceleration mechanism 25 for transmitting rotation of the second hollow motor 24 to the nut shaft 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle steering device, and more particularly to a steer-by-wire steering device and an electric power steering device.

  Conventionally, a steer-by-wire type steering device is known in which a steering wheel and a steering link are not mechanically connected (see, for example, Patent Documents 1 and 2). In the steering device of Patent Document 1, two motors that are concentrically spaced apart in the axial direction are arranged in parallel to the outside of the screw shaft of the ball screw mechanism that constitutes the steering link. Then, by controlling the two motors according to the steering angle of the steering wheel, the rotation of the motor is transmitted to the nut shaft of the ball screw mechanism via the gear reduction mechanism, and the steering link is moved in the axial direction.

  In the steer-by-wire type steering device of Patent Document 2, a screw shaft of a ball screw mechanism that constitutes a steering link is disposed through two hollow motors that are concentrically spaced apart in the axial direction, and the hollow motor is rotated. Is converted into steering operation by a ball screw mechanism.

In addition, as a rack assist type electric power steering device for assisting driving by applying a steering assist force to the rack shaft, the rack shaft is disposed through two hollow motors that are concentrically spaced in the axial direction, and the rotation of the hollow motor is performed. Is converted into an axial movement of the rack shaft by a ball screw mechanism (for example, see Patent Document 3).
JP-A-4-38270 JP 2001-80530 A JP 2004-306860 A

  By the way, in Patent Document 1, a highly reliable steering device is provided using two motors. However, since the two motors are arranged in parallel to the outside of the screw shaft, the cause of increasing the size of the steering device. become.

  Further, in Patent Document 2 and Patent Document 3, space is saved by using a hollow motor concentric with the screw shaft, but the reduction ratio is small because the hollow motor directly rotates the nut shaft of the ball screw. For this reason, a hollow motor having a large output torque is required, which causes the size of the steering device to be increased.

  Further, a turning actuator that rotates the screw shaft linearly by rotating the nut requires a rotation prevention mechanism for the screw shaft. In an electric power steering apparatus such as Patent Document 3, a pinion on the steering shaft side that meshes with a rack provided at an end portion of the screw shaft can be used as a detent for the screw shaft. As described above, in the structure having no pinion, a screw shaft detent mechanism is required separately.

  When the vibration from the tire (vibration of the axial force) is transmitted to the screw shaft while the vehicle is running, the screw shaft generates rotational vibration due to the reaction force from the nut, and noise is generated between the screw shaft and the detent mechanism. There is a problem that it occurs.

  The present invention has been made to eliminate such inconveniences, and an object of the present invention is to provide a vehicle steering apparatus in which the steering actuator can be reduced in size. Another object of the present invention is to provide a vehicle steering apparatus capable of suppressing noise caused by vibrations transmitted from tires.

The above object of the present invention is achieved by the following configurations.
(1) A vehicle steering apparatus including a steering actuator for driving a steering link in an axial direction,
A ball screw mechanism including a screw shaft and a nut shaft;
A hollow motor having an eccentric axis parallel to the axis of the screw shaft and through which the screw shaft is disposed;
A speed reduction mechanism that transmits the rotation of the hollow motor to the nut shaft;
A vehicle steering apparatus comprising:
(2) A vehicle steering apparatus including a steering actuator that drives a screw shaft of a ball screw mechanism in an axial direction,
A steering apparatus for a vehicle, comprising a rotation prevention mechanism for supporting axial movement of a screw shaft by rolling contact and preventing rotation of the screw shaft.
(3) A steer-by-wire vehicle steering apparatus including a steering actuator that drives a steering link in an axial direction,
A ball screw mechanism including a screw shaft and a nut shaft;
A first hollow motor in which a screw shaft is disposed concentrically;
A second hollow motor having an eccentric axis parallel to the axis of the screw shaft and through which the screw shaft is disposed;
A steer-by-wire vehicle steering apparatus comprising:

According to the configuration of (1) of the present invention, the hollow motor has an eccentric axis parallel to the axis of the screw shaft, and the screw shaft is disposed through, so that the motor is arranged parallel to the outside of the screw shaft. Compared with the case where it does, the space saving of a steering actuator can be aimed at.
Further, since the rotation of the hollow motor is transmitted to the nut shaft of the ball screw mechanism through the speed reduction mechanism, the reduction ratio can be made larger than when the nut shaft of the ball screw mechanism is directly rotated by the hollow motor. Thereby, it is not necessary to use a hollow motor having a large output torque, and the steering actuator can be downsized.

  According to the configuration of (2) of the present invention, since the rotation of the screw shaft is supported by rolling contact and the rotation prevention mechanism for preventing the rotation of the screw shaft is provided, vibration from the tire (vibration of axial force) ) Is transmitted to the screw shaft, and even when the screw shaft generates rotational vibration due to the reaction force from the nut shaft, it is possible to satisfactorily prevent rattling. Thereby, generation | occurrence | production of a sound can be avoided.

According to the configuration of (3) of the present invention, the first hollow motor in which the screw shaft is disposed concentrically;
A second hollow motor having an eccentric axis parallel to the axis of the screw shaft and through which the screw shaft is disposed, so that even if one hollow motor cannot output, the other hollow motor A fail-safe system that can be steered by a motor can be obtained.

  Hereinafter, a vehicle steering apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, the present invention is applied to a steer-by-wire type steering device in which the input of the steering wheel is electrically transmitted to the steering mechanism, and the steering actuator drives the screw shaft constituting the steering link in the axial direction. Take the case as an example.

  In the vehicle steering apparatus 10 according to the present embodiment, as shown in FIG. 1, the steering link 11 includes a tie rod 13 that supports the left and right front wheels 12, and both ends in the axial direction coupled to the left and right tie rods 13. And a screw shaft 14 of a ball screw mechanism. Then, the front wheel 12 is steered by driving the screw shaft 14 in the axial direction by the turning actuator 15 controlled by the steering control drive device 16.

  The steering control drive device 16 receives various vehicle information such as vehicle speed, wheel speed, yaw rate, lateral acceleration and cornering force accumulated in the vehicle control device 17 and inputs from the reaction force actuator 19 according to the steering angle of the steering wheel 18. The steering actuator 15 is driven based on the signal, the input signal from the axial force sensor 20, and the like, and the state of the vehicle is appropriately controlled.

  As shown in FIGS. 1 and 2, the steered actuator 15 includes a ball screw mechanism having a screw shaft 14 and two nut shafts 21 and 22, and the screw shaft 14 is disposed concentrically so that one nut shaft 21. A second hollow motor 24 having a first hollow motor 23 for transmitting rotation to the shaft, an eccentric axis Q parallel to the axis P of the screw shaft 14 and through which the screw shaft 14 is disposed, and a second A reduction mechanism 25 that transmits the rotation of the hollow motor 24 to the other nut shaft 22 is provided.

  The nut shafts 21 and 22 are spaced apart from each other in the axial direction. The nut shaft 21 is rotatably supported in a motor housing 26 that houses the first hollow motor 23 via rolling bearings such as a deep groove ball bearing 27 and a pair of angular ball bearings 28. The nut shaft 22 is rotatable through a rolling bearing such as a pair of angular ball bearings 31 in an intermediate housing 30 fastened between the motor housing 26 and a motor housing 29 that houses the second hollow motor 24. It is supported by.

  The first hollow motor 23 includes a rotor 32 integrally provided on the outer peripheral portion of the nut shaft 21 and a stator 33 provided on the inner peripheral portion of the housing 26 so as to face the rotor 32 in the radial direction. . The rotor 32 is rotationally driven by controlling the drive current to the stator 33 by the steering control device 16, and the rotation is directly transmitted to the nut shaft 21, whereby the screw shaft 14 is driven in the axial direction.

  The second hollow motor 24 includes a rotor 35 that is integrally provided on the outer periphery of a hollow offset shaft 34 that is arranged side by side in the axial direction with the nut shaft 22, and a diameter of the rotor 35 on the inner periphery of the motor housing 29. And a stator 36 provided facing the direction.

  The offset shaft 34 has an eccentric axis Q parallel to the axis P of the screw shaft 14 and has a substantially uniform inner diameter larger than the inner diameter of the nut shaft 22, and the screw shaft 14 is in the offset shaft 34. It is arranged through. In the offset shaft 34, the end portion on the side away from the nut shaft 22 is rotatably supported by the motor housing 29 via a rolling bearing such as a deep groove ball bearing 37.

  The rotor 35 is rotationally driven by controlling the drive current to the stator 36 by the steering control device 16, and the rotation is formed on the outer peripheral surface of the offset shaft 34 on the nut shaft 22 side and the end of the nut shaft 22. It is transmitted to the nut shaft 22 through a speed reduction mechanism 25 interposed between the inner diameter surface of the enlarged diameter portion 22a, and thereby the screw shaft 14 is driven in the axial direction.

  The speed reduction mechanism 25 is a traction drive speed reduction mechanism (hereinafter referred to as a wedge roller speed reducer) using a wedge action, and extends between the nut shaft 22 and the offset shaft 34 in the circumferential direction as shown in FIG. Thus, annular spaces 38 having different radial dimensions are formed. In the annular space 38, a fixed guide roller 39 and two wedge rollers 40a and 40b having a smaller diameter than the fixed guide roller 39 are provided.

  The fixed guide roller 39 is rotatable via a needle roller 39d around a carrier pin 39c supported between a fixed carrier 39a fixed to the motor housing 29 and a connecting plate 39b fastened to the fixed carrier 39a. The outer circumferential surface of the annular space 38 is arranged in a state where the outer circumferential surface is in contact with the outer circumferential surface of the offset shaft 34 and the inner circumferential surface of the nut shaft 22.

  The two wedge rollers 40a and 40b are spaced apart from each other so as to be displaceable in the circumferential direction while being pressed and urged by the spring 41 toward the narrow radial region of the annular space 38, respectively.

  When the offset shaft 34 is driven to rotate in the forward direction (in the direction of arrow a), for example, the wedge roller 40a is a region where the radial dimension of the annular space 38 is narrow due to the biasing force of the spring 41 and the rotational force of the offset shaft 34. And the bite between the outer peripheral surface of the offset shaft 34 and the inner peripheral surface of the nut shaft 22, whereby the rotational driving force of the offset shaft 34 is transmitted via the wedge roller 40 a and the fixed guide roller 44. It is transmitted to the nut 21.

  On the other hand, when the offset shaft 34 is driven to rotate in the reverse direction (in the direction of the arrow b), the rotation direction is reversed, so that the wedge roller 40b is slightly displaced toward the region where the radial dimension of the annular space 38 is narrow. The rotary shaft 34 bites between the outer peripheral surface of the offset shaft 34 and the inner peripheral surface of the nut shaft 22, and the rotational driving force of the offset shaft 34 is transmitted to the nut shaft 21 by the same action as described above.

  As described above, the wedge roller speed reducer 25 is a speed reduction mechanism that efficiently transmits rotation without slipping even when a large torque is input, utilizing the wedge action of the wedge rollers 40a and 40b. Therefore, it can be suitably used for a steered actuator.

  Here, the amount of eccentricity e between the offset shaft 34 and the nut shaft 22 (screw shaft 14) is preferably about 1/5 of the diameter of the screw shaft 14, so that the inner diameter of the offset shaft 34 is not extremely increased. Also, the screw shaft 14 can be penetrated, and the increase in size of the second hollow motor 24 can be prevented.

  Further, if the reduction ratio of the wedge roller speed reducer 25 is large, the inertia of the hollow motor 24 with respect to the screw shaft 14 increases, and the steering characteristics of the vehicle may deteriorate, or the outer diameter size may be restricted. For this reason, it is desirable that the reduction ratio is set to about 1.2 to 2.

  Moreover, in this embodiment, as shown in FIG.2 and FIG.4, the rotation prevention mechanism 42 of the screw shaft 14 is provided in the one end side of the screw shaft 14. As shown in FIG. As shown in FIG. 4, the anti-rotation mechanism 42 supports the axial movement of the screw shaft 14 by rolling contact (roller follower) and prevents the screw shaft 14 from rotating. A pair of flat portions 43 are formed on the outer peripheral surface on one end side of the screw shaft 14 along the axial direction so as to be separated from each other by 180 °, and the pair of rollers 44 are in rolling contact with the pair of flat portions 43.

Each of the pair of rollers 44 is rotatably supported by a roller pin 45 fitted in the motor housing 29 via a rolling element such as a needle roller 46, and one roller pin 45 is screwed into the motor housing 29. A pair of preload screws 47 can be pressed in the radial direction. By adjusting this pressing force, the roller 44 is pressed and brought into contact with the flat surface portion 43 so that a preload is applied, and rattling of the screw shaft 14 is prevented.
In addition, when preload is applied so that the screw shaft 14 does not rattle during sliding contact, the efficiency decreases and a large motor must be used. However, as in this embodiment, the rolling contact In some cases, it is not necessary to increase the size of the motor.

  Furthermore, in this embodiment, as shown in FIG. 2, a total of three rotation angle sensors (resolvers) 48 are used for the nut shaft 21, the nut shaft 22 and the offset shaft 34, respectively, to improve reliability. ing.

  And when the correlation of the three rotation angle sensors 48 collapses, it is judged that one rotation angle sensor 48 is abnormal by majority vote. In the case of abnormality, the steering control device 16 issues a warning to the driver to prompt repair, but the steering actuator 15 is controlled by the two remaining normal rotation angle sensors 48 to prevent loss of function.

  Further, since the wedge rotor speed reducer 25 is disposed between the offset shaft 34 and the nut shaft 22 of the second hollow motor 24, a minute slip and a reduction in the reduction ratio occur. The control for correcting the slip is also performed by both the rotation angle sensors 48 of 34.

  Therefore, according to the vehicle steering apparatus 10 of the present embodiment, the second hollow motor 24 has the eccentric axis Q parallel to the axis P of the screw shaft 14, and the screw shaft 14 is disposed through. As compared with the case where the motor is arranged in parallel to the outside of the screw shaft, the space of the steered actuator 15 can be saved.

  Further, since the rotational driving force of the second hollow motor 24 is transmitted to the nut shaft 22 of the ball screw mechanism through the speed reduction mechanism 25, the speed is reduced compared with the case where the nut shaft of the ball screw mechanism is directly rotated by the hollow motor. A large ratio can be taken. Thereby, it is not necessary to use the 2nd hollow motor with big output torque, and size reduction of the steering actuator 15 can be achieved.

  In addition, since the rotation prevention mechanism 42 that supports the axial movement of the screw shaft 14 by rolling contact and prevents the rotation of the screw shaft 14 is provided, vibration from the tire (vibration of axial force) is transmitted to the screw shaft 14. Thus, even when the screw shaft 14 causes rotational vibration due to the reaction force from the nut shafts 21 and 22, rattling can be satisfactorily prevented. Thereby, generation | occurrence | production of a sound can be avoided.

  Further, the first hollow motor 23 in which the screw shaft 14 is disposed concentrically and the second hollow shaft 23 having the eccentric shaft Q parallel to the axis P of the screw shaft 14 and through which the screw shaft 14 is disposed. Therefore, even if one hollow motor is unable to output, it is possible to provide a fail-safe system that can be steered by the other hollow motor.

  Further, the axial force of the screw shaft in the low speed region is secured by the second hollow motor 24 that transmits the rotation to the nut shaft 22 via the speed reduction mechanism 25, and the first hollow motor 23 that does not use the speed reduction mechanism in the high speed region. Can output a wide range of output characteristics.

  The vehicle steering apparatus of the present invention is not limited to this embodiment, and can be appropriately changed without departing from the gist of the present invention.

  The anti-rotation mechanism of the present invention only needs to support the movement of the screw shaft 14 in the axial direction by rolling contact and prevent the screw shaft 14 from rotating. The modification shown in FIGS. The anti-rotation mechanism 50 may be used.

  In this anti-rotation mechanism 50, one end side of the screw shaft 14 is formed in a columnar shape, and a curved roller 51 that is in rolling contact with the outer peripheral surface of the screw shaft 14 along the axial direction is provided using a retainer (not shown). A plurality of roller rows 51 a are arranged in the axial direction of the screw shaft 14, and a plurality of roller rows 51 a are arranged in the circumferential direction of the screw shaft 14.

  The roller 51 is incorporated in a state in which a preload is applied between the outer peripheral surface of the screw shaft 14 and the inner peripheral surface of the motor housing 29 or the inner peripheral surface of the outer cylinder 52 fixed to the motor housing 29. As shown in FIG. 6, it is configured by a combination of a concave curved surface 53 formed at the central portion in the axial direction and convex curved surfaces 54 formed at both ends in the axial direction. The curvature r1 of the concave curved surface 53 is substantially equal to the curvature of the outer peripheral surface of the screw shaft 14, and the curvature r2 of the convex curved surface 54 is substantially equal to the curvature of the inner peripheral surface of the motor housing 29 or the outer cylinder 52.

  Further, as another detent mechanism using rolling contact, a ball spline may be used in a preload state.

  In the steering actuator 15, in addition to the case where the ball screw mechanism is rattling, there is a case where sound is generated due to the axial force vibration from the tire. In this case, the nut shaft 21 side and the nut shaft 22 side It is also possible to solve the problem by controlling the difference in the axial force of the screw shaft 14 generated by the first hollow motor 23 and the second hollow motor 24 to bring the ball screw mechanism into a preload state.

  Further, rattling of the screw shaft 14 may be prevented by setting a constant pressure or a fixed position preload between the two nut shafts 21 and 22. If the two nut shafts 21 and 22 are pre-positioned preloads, the second hollow motor 24 can be shared by the ball screw mechanism on the first hollow motor 23 side, so the load capacity of the ball screw mechanism can be used effectively. Thus, the screw shaft 14 can be reduced in size.

  In this embodiment, the wedge roller speed reducer has been exemplified as the speed reduction mechanism. Instead, the internal gear formed on the nut shaft 22 side and the external gear formed on the offset shaft 34 side are meshed with each other. A gear reducer may be used.

  Furthermore, in this embodiment, although the case where this invention was applied to the steer-by-wire type steering apparatus which electrically transmits the input of a steering wheel to a steering actuator was illustrated, this invention is not limited to this, Steering The present invention may be applied to a rack assist type electric power steering apparatus that assists the axial movement of the rack shaft as a steering link by an actuator. In this case, the rack shaft constitutes a screw shaft of a ball screw mechanism, and a pinion provided on the steering shaft meshes with a rack formed at the end of the rack shaft.

  FIG. 7 compares the screw shaft thrust with respect to the moving speed of the screw shaft in the present embodiment and the conventional example. Since the current that can be supplied from the power supply is limited, the characteristics are shown when the power supply current is limited. The output thrust is determined by the loss of the motor and drive circuit and the mechanical loss with respect to the input power.

  7, when the screw shaft 14 is driven only by the first hollow motor 23, the first conventional example, and when the screw shaft 14 is driven only by the second hollow motor 24 (with a speed reduction mechanism), In the second embodiment, the screw shaft 14 is driven using the first hollow motor 23 and the second hollow motor 24 (with a speed reduction mechanism), and the screw shaft 14 is driven using two first hollow motors 23. This case is referred to as Conventional Example 2.

  The turning actuator 15 is required to have a large thrust at a low speed when it is stationary, and also requires a large thrust for high-speed steering such as emergency avoidance and counter steer.

  The first hollow motor 23 and the second hollow motor 24 use motors having the same characteristics. However, in the first embodiment, in which only the second hollow motor having the speed reduction mechanism 25 (reduction ratio 1.5) is used. It can be seen that the thrust characteristics are improved over almost the entire region as compared with the conventional example 1 in which the current is supplied only to the first hollow motor 23.

  In the case of the second embodiment in which the first hollow motor 23 and the second hollow motor 24 are used at the same time, the current of each motor is reduced and the efficiency is improved. Thereby, necessary characteristics can be satisfied.

  Conventional example 2 uses two first hollow motors 23 without deceleration, and the characteristics of the high-speed steering S portion are slight but cannot be satisfied. Thrust is also insufficient. In order to improve this thrust, it is necessary to make the motor characteristics efficient, but in order to increase the efficiency, it is necessary to enlarge the motor.

  In the second embodiment, when the same motor is used, the thermal rating of the motor at a low speed is 1/2 + reduction ratio ÷ 2 = 1.25 times. Therefore, it can be seen that the characteristics are advantageous at both high speed and low speed.

  Further, in the first embodiment using the second hollow motor 24 with the speed reduction mechanism, thrust is generated over the entire area as compared with the conventional example 1 using the first hollow motor 23. It is considered that the use of two hollow motors 24 (with a speed reduction mechanism) can further reduce the size, but here, when used together with the first hollow motor 23 without speed reduction, the moment of inertia of the motor is increased. This prevents the deterioration of steering characteristics.

  FIG. 8 shows thrust characteristics that the steering actuator 15 can produce during high-speed turning (S portion in FIG. 7). This is also a characteristic when the power that can be supplied is constant.

  Conventional example 3 is an example of the conventional example 2 shown in FIG. 7, which is two first hollow motors 23 (having the same characteristics) that are not decelerated and are optimally redesigned so as to clear the required thrust.

  The horizontal axis in FIG. 8 is the ratio of the electric power supplied to each motor. When electric power is supplied to each motor by 50%, the efficiency is the best, and a thrust that cannot be cleared by one motor can be produced.

  In the third embodiment, the size of the motor is not changed compared to the conventional example 3, and the first hollow motor 23 and the second hollow motor 24 (with a speed reduction mechanism) are applied, and the second hollow motor 24 is reduced to a reduction ratio. This is an example of a case where the vehicle is decelerated at 1.5. Since the efficiency is improved, a larger torque can be produced. In this case, when about 7: 3 electric power is supplied to the second hollow motor 24 on the deceleration side and the first hollow motor 23 on the non-deceleration side, the maximum thrust is generated. If the power supply is 7: 3, the thermal rating at low speed falls, so if there is a margin in low-speed torque, 5: 5 power is supplied.

  In the fourth embodiment, the first hollow motor 23 and the second hollow motor 24 (with a speed reduction mechanism) are applied, and the motor length is reduced to 70% compared to the conventional example 3. Even if the motor is downsized, the same thrust as in Conventional Example 3 can be produced. The ratio that can be reduced by the present invention depends on the required motor efficiency and the motor design, but it is most effective to design the motor efficiency so that the maximum efficiency can be obtained in the S part of FIG.

Next, consider the moment of inertia of the motor rotor. If the inertia moment of one rotor in Conventional Example 3 is J, the inertia moment of the motor viewed from the output shaft of Conventional Example 3 is 2J. Since the inertia moment of the decelerated rotor increases in proportion to the square of the reduction ratio when viewed from the output shaft, if the inertia moment of one rotor of the fourth embodiment is J1 and the reduction ratio is N, this embodiment The total moment of inertia Jb of the motor viewed from the output shaft 4 is Jb = J1 · (1 + N ² ).

  Here, J1 is approximately proportional to the physique (length) of the motor, J1≈0.7J, and N = 1.5, so Jb≈2.2J, and the inertia moment is about 10% of the conventional. Suppressed by the rise. If both the first hollow motor 23 and the second hollow motor 24 are decelerated in this example, the moment of inertia increases by 40 to 50% or more even if the motor can be further reduced in size, and the follow-up performance of the turning actuator. And the steering characteristics may deteriorate.

  As a result, when using a steered actuator that has a hollow roller without a speed reduction mechanism and a hollow roller with a speed reduction mechanism, the optimum thrust is applied while the required thrust is applied and the follow-up performance and steering characteristics do not deteriorate while miniaturizing the motor. It can be seen that this is a simple configuration.

It is the schematic for demonstrating the steering apparatus of the vehicle which is one Embodiment of this invention. It is sectional drawing for demonstrating a steering actuator. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a perspective view for demonstrating the modification of a rotation prevention mechanism. It is a figure which shows the curved roller used for the rotation stopping mechanism of FIG. It is a graph which shows the relationship between the screw shaft moving speed and screw shaft thrust in a present Example and a prior art example. It is a graph which shows the relationship between the input electric power distribution and output thrust in a present Example and a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle steering apparatus 14 Screw shaft 15 Steering actuators 21 and 22 Nut shaft 23 1st hollow motor 24 2nd hollow motor 25 Wedge roller reduction gear (deceleration mechanism)
42 Detent mechanism

Claims (3)

A vehicle steering apparatus including a steering actuator that drives a steering link in an axial direction,
A ball screw having a screw shaft and a nut shaft;
A hollow motor having an eccentric axis parallel to the axis of the screw shaft and through which the screw shaft is disposed;
A speed reduction mechanism for transmitting the rotation of the hollow motor to the nut shaft;
A vehicle steering apparatus comprising: A vehicle steering apparatus including a steering actuator that drives a screw shaft of a ball screw in an axial direction,
A steering apparatus for a vehicle, comprising: a rotation prevention mechanism that supports axial movement of the screw shaft by rolling contact and prevents rotation of the screw shaft. A steer-by-wire vehicle steering apparatus including a steering actuator that drives a steering link in an axial direction,
A ball screw having a screw shaft and a nut shaft;
A first hollow motor in which the screw shaft is disposed concentrically;
A second hollow motor having an eccentric axis parallel to the axis of the screw shaft and through which the screw shaft is disposed;
A steer-by-wire vehicle steering apparatus comprising:

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