JP4785763B2 - Vehicle steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle capable of surely locking a lock gear and making a backup system function under abnormal conditions of a system. <P>SOLUTION: In a cut-off state of a mechanical connection between a steering wheel and a steering gear box, the amount of operation of the steering wheel is converted into an electric signal, and a steering motor provided in the steering gear box is driven based on the electric signal to steer the vehicle wheels, and moreover, a steering reaction force motor connected to the steering wheel is driven according to the amount of operation to give a steering reaction force to the steering wheel in this steering device. The device is provided with a clutch mechanism fitting a locking claw into the lock gear to connect the steering wheel and the steering gear box mechanically. Furthermore, the lock claw is provided with a plurality of claw members engaged with the tooth groove section of the lock gear with different phases. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a technique for improving a steer-by-wire vehicle steering apparatus having a backup mechanism.

  2. Description of the Related Art Conventionally, as a general vehicle steering apparatus, a structure in which a steering mechanism is connected to a steering wheel and wheels are steered via the steering mechanism by a steering force of the steering wheel is known.

  Also, in recent years, the steering mechanism is mechanically separated from the steering wheel, and the steering actuator generates steering power according to the steering amount, and the wheel is transmitted by transmitting this steering power to the steering mechanism. A steer-by-wire (steer-by-wire, hereinafter abbreviated as “SBW”) vehicle steering apparatus is known.

  In such a vehicle steering apparatus, since the steering wheel and the steering gear box are not mechanically connected, if the steering motor fails, the wheel may not be steered even if the steering wheel is operated. Therefore, there are some equipped with a backup system to enable steering even when the system is abnormal.

  As this backup system, the rotating shaft of the steering wheel and the input shaft of the steering mechanism are connected by a planetary gear mechanism (clutch), and one constituent gear of this planetary gear mechanism can be made non-rotatable by a lock member. (For example, refer to Patent Document 1).

This backup system normally functions as a steer-by-wire steering device by mechanically separating the steering wheel and the input shaft of the steering mechanism by allowing each component gear of the planetary gear mechanism to freely rotate. And mechanically connecting the steering wheel and the input shaft of the steering mechanism by driving the lock member with a solenoid and locking one component gear (lock gear) of the planetary gear mechanism so as not to rotate. It can be made to function as a steering device (non-steer-by-wire type steering device) that connects and steers the steered wheels directly with the steering wheel. In this backup system, the locking member is locked even when the system is stopped.
JP-A-2005-29016

  However, in the backup system described above, the pitch of the lock gear teeth is reduced with respect to the pitch of the lock member (hereinafter referred to as “lock pitch”), and the lock gear is quickly locked during high-speed rotation. For example, when the lock pitch is reduced and the lock gear rotates at high speed, the corners of the lock gear and the claw of the lock member collide with each other. There was a problem that it was not possible to lock properly by being played. On the other hand, if the lock pitch is increased to make it difficult to play the lock claw, the angle for engaging the lock claw also increases.

  Therefore, the present invention has been made in view of the above-described problems, and provides a vehicle steering apparatus that can reliably lock a lock gear and function a backup system when a system abnormality occurs. Objective.

The present invention proposes the following matters in order to solve the above problems.
(1) The present invention converts a steering wheel operation amount into an electrical signal in a state in which the mechanical connection between the steering wheel and the steering gear box is cut off, and a steering motor provided in the steering gear box based on the electrical signal. In a vehicle steering device that applies a steering reaction force to the steering wheel by driving a steering reaction force motor connected to the steering wheel in accordance with the operation amount. A plurality of claw members, each having a clutch mechanism that mechanically connects the steering wheel and the steering gear box by fitting a claw, wherein the lock claw engages with a tooth groove portion of the lock gear at different phases. The vehicle steering apparatus characterized by providing is proposed.

  According to this invention, the lock claw includes the plurality of claw members that engage with the tooth groove portion of the lock gear at different phases. Therefore, when locking is performed by engaging the lock claw with the tooth of the lock gear, the lock gear rotates at a high speed because the claw members of the lock claw engage with the tooth groove of the lock gear at different phases. Even when this is done, the plurality of claw members are not simultaneously repelled by the teeth of the lock gear, so that the lock gear can be reliably locked.

  According to the present invention, the lock claw includes a plurality of claw members that engage with the tooth groove portion of the lock gear at different phases, so that even when the lock gear rotates at high speed, the plurality of claw members rotate. Since all the pawl members are not simultaneously repelled by the teeth of the lock gear, the lock gear can be reliably locked. Further, since the lock gear can be securely locked, there is an effect that the time until the lock gear is locked can be shortened. Further, there is an effect that the lock pitch can be set without restriction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

<Configuration of vehicle steering device>
The configuration of the vehicle steering apparatus according to the present embodiment will be described with reference to FIG.
The vehicle steering device 10 mechanically separates the steering mechanism 30 from the steering wheel 21 as a steering member, and generates steering power from the steering actuator 38 according to the steering amount of the steering wheel 21. This is a so-called steer-by-wire (SBW) type vehicle steering apparatus in which the steering mechanism 30 steers the left and right steered wheels 35, 35 by transmitting the steering power to the steering mechanism 30. .

  The steering mechanism 20 of the vehicle steering apparatus 10 includes a steering wheel 21 gripped by the driver, a steering shaft 22 connected to the steering wheel 21, a steering angle sensor 23 that detects the steering angle of the steering wheel 21, and the steering wheel 21. A reaction force motor 24 that generates a steering reaction force (reaction force torque) against the motor, a motor rotation angle sensor 25 that detects the rotation angle of the reaction force motor 24, and a reaction force transmission mechanism 26 that transmits the steering reaction force to the steering shaft 22. And a torque sensor 32 for detecting the torque of the steering shaft 22.

  Here, the reaction force motor 24 is an electric motor, and the reaction force transmission mechanism 26 is coupled to the worm 27 provided on the motor shaft of the reaction force motor 24 and the steering shaft 22, and the worm wheel meshed with the worm 27. 28 is a worm gear mechanism, that is, a booster mechanism. The steering reaction force is an operation resistance added to the steering wheel 21 in the rotational direction.

  The turning mechanism 30 includes an input shaft 31 for inputting a steering force of the steering shaft 22, a rack shaft 34 connected to the input shaft 31 via a rack and pinion mechanism 33, and left and right turning wheels at both ends of the rack shaft 34. Tie rods 36 and 36 and knuckles 37 and 37 that connect 35 and 35 (for example, front wheels), a steering actuator 38 that adds steering power to the input shaft 31, and an input shaft that detects the rotation angle of the input shaft 31. The rotation angle sensor 41 and a rack shaft position sensor 42 for detecting the position of the rack shaft 34 are configured.

  The rack and pinion mechanism 33 includes a pinion 43 formed on the input shaft 31 and a rack 44 formed on the rack shaft 34. The steering actuator 38 includes a steering power motor 45 that generates steering power and a steering power transmission mechanism 46 that transmits the steering power to the input shaft 31. Here, the turning power motor 45 is an electric motor. The turning power transmission mechanism 46 includes a worm 47 provided on the motor shaft of the turning power motor 45 and a worm gear 48 that is coupled to the input shaft 31 and meshed with the worm 47, that is, a boosting mechanism. It is.

  As described above, the vehicle steering apparatus 10 is an end take-off type steering apparatus in which the steering torque is extracted from both ends of the rack shaft 34. Further, the vehicle steering apparatus 10 is configured such that a planetary gear mechanism 51 connects a steering shaft 22 provided on the steering wheel 21 and an input shaft 31 provided on the steering mechanism 30. Specifically, the input shaft 31 is connected to the steering shaft 22 via the clutch mechanism 51, the first connecting shaft 52, the first universal shaft joint 53, the second connecting shaft 54, and the second universal shaft joint 55. Is.

  The control unit 61 receives detection signals from the steering angle sensor 23, the motor rotation angle sensor 25, the steering torque sensor 32, the pinion sensor 41, and the rack shaft position sensor 42, and also detects a vehicle speed sensor 62 that detects the traveling speed of the vehicle. In response to detection signals from the yaw rate sensor 63 for detecting the yaw angular velocity (the angular velocity of the yaw motion), the acceleration sensor 64 for detecting the acceleration of the vehicle, and other various sensors 65, the reaction force motor 24, the turning power motor 45, A control signal is issued to the planetary gear mechanism 51.

  That is, the control unit 61 automatically sets the steering reaction force according to the operation of the steering wheel 21 by controlling the reaction force motor 24, adds the steering reaction force to the steering wheel 21, and Control can be performed as in 1) to (4).

(1) When the worm wheel 28 is rotated by the reaction force motor 24 in the direction opposite to the steering direction of the steering wheel 21, the steering force of the steering wheel 21 is canceled by the steering reaction force of the reaction force motor 24. work. For this reason, when the steering wheel 21 is steered, a steering force that is larger by the steering reaction force is required.

(2) When the worm wheel 28 is rotated in the same direction as the steering direction of the steering wheel 21 by the reaction force motor 24, the action of adding the steering reaction force of the reaction force motor 24 to the steering force of the steering wheel 21 works. . For this reason, when the steering wheel 21 is steered, a steering force that is as small as the steering reaction force is sufficient.

(3) When the steering wheel 21 is held at an arbitrary angle in a stopped state, the worm wheel 28 is adjusted while adjusting the steering reaction force of the reaction force motor 24 in the direction opposite to the rotation direction of the steering wheel 21 until then. A holding force is generated by rotating the.

(4) When the steering wheel 21 is subsequently returned, a return force (steering reaction force) corresponding to so-called self-aligning torque that automatically returns the steering wheel 21 to the neutral position of the steering wheel 21 is a reaction force motor. 24 is transmitted to the worm wheel 28.

  Further, the control unit 61 automatically sets the characteristics of the angle ratio of the steered wheels 35 and 35 to the steering angle of the steering wheel 21, that is, the steering characteristics, by controlling the steered power motor 45. can do. That is, since the steering mechanism 30 is mechanically separated from the steering wheel 21 as described above, the correspondence between the steering angle of the steering wheel 21 and the operation amount of the steering actuator 38 is not subject to mechanical restrictions. Can be set. As a result, the steering characteristics can be flexibly set according to the traveling state of the vehicle, such as the vehicle speed, the degree of turning of the vehicle, and the presence or absence of acceleration / deceleration. Accordingly, the degree of freedom in designing the vehicle steering apparatus 10 can be increased.

  Further, in the vehicle steering apparatus 10, the steering shaft 22 of the steering mechanism 20 and the input shaft 31 of the steering mechanism 30 include a planetary gear mechanism 51, a first connecting shaft 52, a first universal shaft joint 53, and a second connecting shaft. The shaft 54 and the second universal shaft joint 55 are connected.

Next, the planetary gear mechanism 51 will be described with reference to the schematic diagram of FIG.
The planetary gear mechanism 51 meshes a plurality of, for example, three planetary gears 72... With the central sun gear 71, meshes the planetary gear 72. Each carrier 74 is configured to be rotatably attached.

  The sun gear 71, the ring gear 73 and the carrier 74 are arranged concentrically with the first connecting shaft 52 as the center. The ring gear 73 is connected to the steering shaft 22, the carrier 74 is connected to the first connecting shaft 52, the sun gear 71 is supported to be rotatable relative to the first connecting shaft 52, and the planetary gears 72. On the other hand, they are arranged radially at an equal pitch. In FIG. 2, reference numeral 92 denotes a first bearing that supports the steering shaft 22, reference numerals 93 and 93 denote second bearings that support the first connecting shaft 52, and reference numeral 94 denotes a third bearing that supports the ring gear 73.

  Further, the planetary gear mechanism 51 includes a lock mechanism 80 that prevents the sun gear 71 from rotating. The lock mechanism 80 includes a lock gear 81 provided integrally with the sun gear 71, a swing arm (lock member) 82 that can be fitted to the teeth of the lock gear 81, and the swing arm 82 in a locked state or an unlocked state. And a solenoid (lock driving means) 83 for driving the motor.

  The locking gear 81 is disposed concentrically with the first connecting shaft 52 and is provided to be rotatable relative to the first connecting shaft 52. The swing arm 82 is provided so as to be rotatable about a support shaft 85, and has a lock claw 84 made up of a plurality of claw members engaged with the tooth groove portion of the lock gear 81 at different phases at one end. ing. The swing arm 82 is biased by a return spring (not shown) in a rotational direction that causes the lock claw 84 to approach the lock gear 81, and the tip of the push rod 88 of the solenoid 83 is abutted against the other end of the swing arm 82. Yes.

  In the non-excited state of the solenoid 83, the push rod 88 is retracted as shown by the solid line in FIG. 3, and at this time, the swing arm 82 is rotated in the direction approaching the locking gear 81 by the return spring. The lock claw 84 of the arm 82 is engaged with the teeth of the locking gear 81 (hereinafter, this state is referred to as a locked state), and the rotation of the locking gear 81 is prevented. As a result, the sun gear 71 cannot be rotated. The vehicle steering apparatus 10 is configured such that when the system is stopped, the solenoid 83 is de-energized and the lock mechanism 80 is locked.

  On the other hand, when the solenoid 83 is excited, the push rod 88 moves forward as shown in FIG. 2 (as shown by a two-dot chain line in FIG. 3), and pushes the other end of the swing arm 82 against the elasticity of the return spring. To do. As a result, the swing arm 82 rotates against elasticity, the lock claw 84 is separated from the locking gear 81, and the lock is released (hereinafter, this state is referred to as an unlocked state).

Next, the operation of the planetary gear mechanism 51 will be described.
When an ignition switch (not shown) is ON, the solenoid 83 is normally excited and the lock mechanism 80 is unlocked. At this time, the locking gear 81 can rotate, and the sun gear 71 integrated with the locking gear 81 can also rotate. As a result, the planetary gears 72... And the ring gear 73 can rotate without being restricted from each other, and the steering force is not transmitted from the steering shaft 22 to the input shaft 31.

  That is, when the lock mechanism 80 is unlocked, the steering torque is interrupted in the planetary gear mechanism 51, and the steering wheel 21 and the steered wheel 35 can be substantially separated. At this time, as will be described later, the reaction force motor 24 and the steering motor 45 are independently controlled by the control unit 61, and the vehicle steering device 10 becomes a steer-by-wire vehicle steering device.

  On the other hand, when the electrical connection between the steering mechanism 20 and the steering mechanism 30 is released due to some factor, or when the ignition switch is turned OFF, the solenoid 83 is in a non-excited state, and the lock mechanism 80 is locked. At this time, the locking gear 81 is made non-rotatable, and the sun gear 71 integrated with the locking gear 81 is also non-rotatable. In this state, when the steering wheel 21 is rotated and the ring gear 73 is rotated, the rotational force is transmitted to the carrier 74 via the planetary gears 72..., The carrier 74 is rotated, and the planetary gears 72. To do.

  In other words, when the lock mechanism 80 is locked, the steering torque can be transmitted from the steering shaft 22 to the first connecting shaft 52 via the planetary gear mechanism 51, and the steering mechanism 20 and the steering mechanism 30 are connected to the planetary gear 72. .. and mechanically connected via the ring gear 73, and the steering wheel 21 and the steered wheel 35 can be mechanically coupled. As a result, the rotational motion of the steering wheel 21 can be mechanically converted into the axial motion of the rack shaft 9, and the steered wheels 35 can be steered.

  That is, at this time, the vehicle steering device 10 is not steer-by-wire, and becomes a steering device capable of manually turning the steered wheels 35. At this time, the reaction force motor 24 is controlled by the control unit 61 so as not to generate a steering reaction force. In this case, the road surface reaction force received by the steered wheels 35, 35 acts on the steering shaft 22 via the steered mechanism 30 and the planetary gear mechanism 51.

  That is, the steering wheel 21 and the steered wheel 35 can be mechanically connected when the lock mechanism 80 is locked, and the steering wheel 21 and the steered wheel 35 are substantially separated when the lock mechanism 80 is unlocked. be able to.

  That is, in the vehicle steering apparatus 10, the planetary gear mechanism 51 constitutes a clutch, and the lock mechanism 80 constitutes a clutch switching unit that switches between engagement and disengagement of the clutch. The unlocked state of the lock mechanism 80 corresponds to the clutch disengaged state, and the locked state of the lock mechanism 80 corresponds to the clutch connected state.

  Next, each embodiment will be described with reference to FIGS.

<Example 1>
As shown in FIG. 4, the lock claw 84 according to the first embodiment includes two claw members 84 a and 84 b that engage with the tooth groove portion of the locking gear 81 at different phases. The lock claw 84 according to this embodiment is fitted to the lock gear 81 from a direction substantially perpendicular to the teeth of the lock gear 81 when the push rod 88 is retracted in the non-excited state of the solenoid 83. .

  Therefore, as in the present embodiment, the lock claw 84 is constituted by the two claw members 84a and 84b that engage with the tooth groove portion of the lock gear 81 at different phases, so that the teeth of the lock gear 81 can be obtained. Since the pitch at which the lock is applied becomes 1/2 with respect to the pitch, the steering invalid angle can be reduced, and even when the lock gear is rotating at high speed, both the claw members are The locking gear 81 can be reliably locked in a short time without being bounced by the teeth of the locking gear 81.

  In the above description, the case where the lock claw 84 has two claw members 84a and 84b has been described. However, by increasing the number of claw members, the pitch at which the lock is applied can be further reduced.

<Example 2>
As shown in FIG. 5, the lock claw 84 according to the second embodiment includes two claw members 84 c and 84 d that engage with the tooth groove portion of the lock gear 81 at different phases. The claw members 84c and 84d are each formed in a key shape. The lock claw 84 according to this embodiment is fitted to the lock gear 81 from a direction substantially parallel to the teeth of the lock gear 81 when the push rod 88 is retracted in the non-excited state of the solenoid 83. .

  Therefore, as in the present embodiment, the lock claw 84 is constituted by the two key-type claw members 84c and 84d that engage with the tooth groove portion of the lock gear 81 at different phases, so that the lock gear 81 is provided. Since the pitch at which the lock is applied is halved with respect to the pitch of the teeth, the steering invalid angle can be reduced, and even when the lock gear is rotating at high speed, The claw member is not repelled by the teeth of the locking gear 81, and the locking gear 81 can be reliably locked in a short time.

  In the above description, the case where the configuration of the lock claw 84 is the two cases of the claw member 84c and the claw member 84d has been described. However, the pitch at which the lock is applied can be further reduced by increasing the number of claw members.

<Example 3>
As shown in FIG. 6, the lock claw 84 according to the third embodiment is provided with two claw members 84 e and 84 f that are engaged with the tooth groove portion of the lock gear 81 at different phases substantially symmetrically. The claw members 84e and 84f are each formed in a key shape. The lock claw 84 according to the present embodiment includes a solenoid 83 for each of the claw members 84e and 84f. When the push rod 88 is retracted in the non-excited state of the solenoid 83, the lock claw 84 has teeth. On the other hand, the lock gear 81 is fitted from a substantially parallel direction.

  Therefore, as in the present embodiment, the lock claw 84 is composed of two claw members 84e and 84f that engage with the tooth groove portion of the lock gear 81 at different phases, so that the tooth of the lock gear 81 can be reduced. Since the pitch at which the lock is applied becomes 1/2 with respect to the pitch, the steering invalid angle can be reduced, and even when the lock gear is rotating at high speed, both the claw members are The locking gear 81 can be reliably locked in a short time without being bounced by the teeth of the locking gear 81.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

It is a lineblock diagram of the steering device for vehicles concerning this embodiment. It is a mimetic diagram of a clutch mechanism concerning this embodiment. It is a block diagram which shows an example of the locking mechanism in the steering apparatus for vehicles which concerns on this embodiment. 1 is a configuration diagram according to Embodiment 1. FIG. 6 is a configuration diagram according to Embodiment 2. FIG. 6 is a configuration diagram according to Embodiment 3. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Steering device for vehicles, 21 ... Steering wheel, 23 ... Steering angle sensor, 24 ... Reaction force motor, 38 ... Steering motor, 51 ... Planetary gear mechanism, 80 ...・ Lock mechanism, 81 ... Lock gear, 82 ... Swing arm, 83 ... Solenoid, 84 ... Lock claw,

Claims (1)

With the mechanical connection between the steering wheel and the steering gear box disconnected, the operation amount of the steering wheel is converted into an electrical signal, and the steering motor provided in the steering gear box is driven based on the electrical signal to rotate the wheel. In a steering apparatus for a vehicle that steers and applies a steering reaction force to the steering wheel by driving a steering reaction force motor connected to the steering wheel according to the operation amount.
A clutch mechanism for mechanically connecting the steering wheel and the steering gear box by fitting a lock claw to a lock gear;
The vehicle steering apparatus according to claim 1, wherein the lock claw includes a plurality of claw members that engage with the tooth groove portion of the lock gear at different phases.

Images