JP5408472B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus.

A vehicle steering apparatus includes an input shaft connected to a steering wheel, an output shaft connected to a steering mechanism, and a transmission ratio variable mechanism that connects the input shaft and the output shaft so as to be differentially rotatable. (For example, see Patent Documents 1 and 2).
The transmission ratio variable mechanism of Patent Document 1 includes a sun gear fixed to the input shaft, a plurality of planetary gears arranged around the sun gear, a ring gear surrounding the planetary gear, a carrier holding the planetary gear and fixed to the output shaft, Is included. A motor for making the transmission ratio variable is connected to the ring gear. When a failure occurs in the motor, powder is sprayed onto the meshing portion between the planetary gear and the sun gear or the meshing portion between the planetary gear and the ring gear. As a result, the planetary gear and the sun gear, and the planetary gear and the ring gear are locked, and these gears rotate together. Thereby, the input shaft and the output shaft are directly connected, and the torque of the steering wheel can be transmitted to the steering mechanism. At this time, the carrier is not locked.

  The transmission ratio variable mechanism of Patent Document 2 includes a first sun gear fixed to the input shaft, a second sun gear fixed to the output shaft and arranged coaxially with the first sun gear, and the first and second A planetary gear meshing with both sun gears and a carrier for holding the planetary gear are included. A motor for making the transmission ratio variable is connected to the carrier. In addition, the carrier rotation is locked at the time of failure in which an abnormality occurs in the motor. As a result, the transmission ratio between the first sun gear and the second sun gear via the planetary gear becomes constant, the input shaft and the output shaft are mechanically connected, and the torque of the steering wheel can be transmitted to the steering mechanism.

Japanese Patent Laying-Open No. 2003-267242 (FIG. 5) JP 2008-74367 A

  In Patent Document 2, the gears are locked (gear-locked) by foreign matter such as iron powder being caught between the planetary gear and the first and second sun gears, or by the teeth of each gear being deformed. It is possible to do. For example, in order to release the gear lock by operating the steering wheel while the carrier is locked, it is necessary to apply a large torque to the steering wheel, and the steering feeling is lacking. On the other hand, in this case, since the first sun gear, the planetary gear, and the second sun gear rotate together, torque can be transmitted between the input shaft and the output shaft without locking the carrier. Can be linked.

  The present invention has been made under such a background, and an object of the present invention is to provide a vehicle steering apparatus that can improve steering feeling during a failure.

In order to achieve the above object, the present invention is interposed between an input element (19) connected to the steering member (2), an output element (20) connected to the steered wheel side member (6), and the input element and the output element. Rotation of the steered wheel side member with respect to the rotation angle (θ1) of the steering member, including a planetary element (21) and a differential mechanism including a carrier (22) supporting the planetary element and a transmission ratio variable mechanism motor (18) The transmission ratio variable mechanism (8) capable of changing the transmission ratio (θ2 / θ1), which is the ratio of the angle (θ2), and the transmission ratio variable mechanism motor are controlled based on the target transmission ratio (θ2 _t / θ1 _t ). Motor control means (73), a lock mechanism (32) capable of locking the carrier, first abnormality detection means (71) for detecting an abnormality in the output of the transmission ratio variable mechanism, and the target transmission ratio Deviation (| θ2) from the actual transmission ratio (θ2 / θ1) _{When t} / θ1 _t− θ2 / θ1 |) is equal to or greater than a predetermined value (α2), a second abnormality detecting means (72) for detecting abnormality of the differential mechanism and a lock for controlling the operation of the lock mechanism An abnormality of the output of the variable transmission ratio mechanism is that the rotational speed of the output element deviates from a target rotational speed by more than a predetermined value. The driving resistance between the planetary element and at least one of the input element and the output element is increased, or these three elements are locked, and the lock control means is controlled by the first abnormality detection means. When the abnormality of the output of the variable ratio mechanism is detected, on the condition that the abnormality of the differential mechanism is detected by the second abnormality detection means, the locking of the carrier by the lock mechanism is prohibited, On condition that the abnormality of the differential mechanism is not detected by the second abnormality detecting means, by said locking mechanism to lock the carrier, said motor control means, the transmission ratio variable mechanism by the first abnormality detecting means abnormality of the output is to provide a vehicle steering system (1), characterized that you stop the driving of the motor for the transmission ratio variable mechanism when it is detected (claim 1).

  In the present invention, the output abnormality of the transmission ratio variable mechanism means that the rotational speed of the output element deviates greatly from a desired rotational speed due to, for example, the runaway of the motor for variable transmission ratio mechanism. Further, the abnormality of the differential mechanism means that, for example, foreign matter such as iron powder enters between the planetary element and at least one of the input element and the output element, or the driving resistance between them increases or three elements Means to lock.

  According to the present invention, when an abnormality in the output of the transmission ratio variable mechanism is detected by the first abnormality detection means, the steering member and the steered wheel side member are connected so as to transmit torque without impairing the steering feeling. be able to. Specifically, when an abnormality in the output of the variable transmission ratio mechanism is detected by the first abnormality detection unit, the second abnormality detection unit detects that an abnormality in the differential mechanism is detected. Locking is prohibited. At this time, even if the carrier is not locked, the planetary element, the input element, and the output element are locked or can transmit torque in a state close to being locked. Therefore, the input element and the output element can transmit torque with a substantially constant transmission ratio, and the steering member and the steered wheel side member can transmit torque. At this time, since the carrier is not locked, the steering member can be operated with a relatively small torque. Further, the carrier is locked on condition that no abnormality of the differential mechanism is detected by the second abnormality detecting means. At this time, since the driving resistance between the planetary element and the input element and the output element remains small, each element can be smoothly engaged. When the carrier is locked in this state, torque can be transmitted between the input element and the output element at a constant transmission ratio, and as a result, the steering member can be operated with a relatively small torque. Thus, even when an abnormality occurs in the output of the transmission ratio variable mechanism, the steering member can be operated with a relatively small torque, so that the steering feeling during a failure can be improved.

Further, when an abnormality of the heat Itaruhi variable mechanism is detected, the steering member and the steered wheel side member while being connected to transmit torque, the transmission ratio variable mechanism motor is stopped. Therefore, the transmission ratio variable mechanism motor can be stopped while maintaining a state in which the steered wheels can be steered by operating the steering member.

Further, at least one of the input element and output element, with the planet elements, due to the biting of a foreign matter or the like can detect that an increase in driving resistance or lock has occurred, as a result, the differential mechanism Can be reliably detected.

  In the above description, numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles concerning one embodiment of the present invention. It is sectional drawing of the principal part of FIG. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which follows the IV-IV line of FIG. It is an enlarged view of the principal part around the solenoid of FIG. It is sectional drawing of the principal part in alignment with the VI-VI line of FIG. It is sectional drawing of the principal part for demonstrating the operation | movement which controls rotation of a carrier. It is a block diagram which shows the principal part of the electrical structure of the steering apparatus for vehicles. It is a flowchart of an example of the control regarding abnormality of the steering apparatus for vehicles.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus 1 according to an embodiment of the present invention. Referring to FIG. 1, a vehicle steering apparatus 1 applies a steering torque applied to a steering member 2 such as a steering wheel to left and right steered wheels 4L and 4R via a steering shaft 3 as a steering shaft. The steering is given. The vehicle steering apparatus 1 changes the transmission ratio θ2 / θ1 that is the ratio of the turning angle θ2 (rotation angle) of the second shaft 6 as the steered wheel side member to the steering angle θ1 (rotation angle) of the steering member 2. It has a function to do.

The vehicle steering apparatus 1 includes a steering member 2 and a steering shaft 3 connected to the steering member 2. The steering shaft 3 includes a first shaft 5 as a first portion, and a second shaft 6 as a second portion arranged coaxially with the first shaft 5.
The first shaft 5 has an input shaft 5 a connected to the steering member 2, and an output shaft 5 b connected to the input shaft 5 a and the torsion bar 7 so as to be relatively rotatable. The permissible value of relative rotation between the input shaft 5a and the output shaft 5b via the torsion bar 7 is a slight value, and it can be considered that the input shaft 5a and the output shaft 5b rotate substantially in the same direction.

  A transmission ratio variable mechanism 8 is provided between the output shaft 5 b of the first shaft 5 and the second shaft 6. The transmission ratio variable mechanism 8 includes a planetary gear mechanism 17 as a differential mechanism and a planetary gear mechanism motor 18 as a transmission ratio variable mechanism motor. The transmission ratio variable mechanism 8 can change the transmission ratio θ2 / θ1 as a gear ratio between the output shaft 5b and the second shaft 6. The second shaft 6 is connected to the steered wheels 4L and 4R through a universal joint 9, an intermediate shaft 10, a universal joint 11, and a steering mechanism 12.

The steering mechanism 12 includes a pinion shaft 13 connected to the universal joint 11, a rack 14 a that has a rack 14 a that meshes with the pinion 13 a at the tip of the pinion shaft 13, and that extends in the left-right direction of the vehicle. Knuckle arms 16R and 16L connected to the pair of end portions via tie rods 15R and 15L, respectively.
With the above configuration, the steering torque from the steering member 2 is transmitted to the steering mechanism 12 via the first shaft 5, the planetary gear mechanism 17, the second shaft 6, and the like. In the steering mechanism 12, the rotation of the pinion 13a is converted into the movement of the rack shaft 14 in the axial direction, and the corresponding knuckle arms 16R and 16L rotate through the tie rods 15R and 15L, respectively. Thereby, the corresponding steered wheels 4R and 4L connected to the knuckle arms 16R and 16L are respectively steered.

The planetary gear mechanism 17 connects the output shaft 5b of the first shaft 5 and the second shaft 6 so as to be differentially rotatable, and is driven by a planetary gear mechanism motor 18 to thereby transmit a transmission ratio θ2 / θ1. Is changed.
The planetary gear mechanism 17 includes a first sun gear 19 as an input element that can be rotated along with the output shaft 5 b of the first shaft 5, and an axis that coincides with the axis of the first sun gear 19. , A second sun gear 20 as an output element that can rotate with the second shaft 6, a planetary gear 21 as a planetary element that meshes with both the first and second sun gears 19, 20, and a planetary gear And a carrier 22 as an annular predetermined element that supports the motor 21 so as to be capable of rotating and rotating along the axis of the first and second sun gears 19 and 20.

The first and second sun gears 19 and 20 and the planetary gear 21 are each provided as a rotation transmission element, and are formed using, for example, a helical gear. Note that other parallel shaft gears such as spur gears may be used instead of the helical gears.
The planetary gear 21 is for associating the first and second sun gears 19 and 20 with each other, and a plurality (two in the present embodiment) are arranged in the circumferential direction of the steering shaft 3. Each planetary gear 21 extends parallel to the axis of the steering shaft 3 and meshes with both the first and second sun gears 19 and 20.

In the planetary gear 21, the number of teeth of the portion that meshes with the first sun gear 19 is the same as the number of teeth of the portion that meshes with the second sun gear 20.
The number of teeth of the first sun gear 19 is different from the number of teeth of the second sun gear 20, and at least one of the first sun gear 19 and the second sun gear 20 (for example, the second sun gear 20). ) Is formed using a shift gear. This shift gear is a negative shift gear that is shifted in the direction in which the diameter of the pitch circle is reduced, or a positive shift gear that is shifted in the direction in which the diameter of the pitch circle is increased.

The planetary gear mechanism motor 18 is for rotating the carrier 22. By changing the rotation speed of the carrier 22, the transmission ratio between the first sun gear 19 and the second sun gear 20 is changed, and the transmission ratio θ2 / θ1 is changed.
The planetary gear mechanism motor 18 includes, for example, a brushless motor disposed coaxially with the steering shaft 3, and includes a rotor 18a fixed to the carrier 22 and a stator 18b surrounding the rotor 18a and fixed to the housing 36. Contains.

  The vehicle steering apparatus 1 is provided with a reaction force compensation motor 23 for compensating the steering reaction force of the steering member 2. The reaction force compensating motor 23 is, for example, a brushless motor disposed coaxially with the steering shaft 3. The rotor 23 a is fixed to the output shaft 5 b of the first shaft 5, and the rotor 23 a is surrounded and fixed to the housing 36. Stator 23b.

The planetary gear mechanism motor 18 and the reaction force compensating motor 23 are controlled by an ECU 24 (Electronic Control Unit) including a CPU, a RAM, and a ROM, respectively. The ECU 24 is connected to the planetary gear mechanism motor 18 via the drive circuit 25a, and is connected to the reaction force compensation motor 23 via the drive circuit 25b.
Further, a steering angle sensor 26, a torque sensor 27, a planetary gear mechanism motor resolver 33, a turning angle sensor 28, a vehicle speed sensor 29, and a yaw rate sensor 30 are connected to the ECU 24, respectively.

  From the steering angle sensor 26, a signal about the rotation angle of the input shaft 5a of the first shaft 5 is input as a value corresponding to the steering angle θ1 that is the operation amount from the steering neutral position of the steering member 2. From the torque sensor 27, a signal regarding the torque acting on the first shaft 5 is input as a value corresponding to the steering torque T of the steering member 2. From the planetary gear mechanism motor resolver 33, a signal regarding the rotation angle θm of the rotor 18a of the planetary gear mechanism motor 18 is input. From the turning angle sensor 28, a signal regarding the rotation angle of the second shaft 6 is input as a value corresponding to the turning angle θ2. A signal regarding the vehicle speed V is input from the vehicle speed sensor 29. A signal regarding the yaw rate γ of the vehicle is input from the yaw rate sensor 30.

The ECU 24 controls driving of the planetary gear mechanism motor 18 and the reaction force compensation motor 23 based on input signals from the sensors 26 to 30 and 33.
The vehicle steering apparatus 1 includes a solenoid 32 as a lock mechanism that can lock the carrier 22 of the planetary gear mechanism 17.
The solenoid 32 includes a restriction member 31. The regulating member 31 regulates the rotation of the carrier 22 by engaging with a ring member 60 as an annular member that rotates together with the carrier 22.

The restricting member 31 is displaced to the engagement release position D2 and the engagement position D1. The engagement position D1 is a position where the restriction member 31 is engaged with the ring member 60 and the rotation of the ring member 60 is restricted. The engagement release position D2 is the position where the restriction member 31 is engaged with the ring member 60. It refers to a position where the rotation of the ring member 60 is not restricted.
The solenoid 32 is driven and controlled by the ECU 24. When the ECU 24 detects a first abnormality described later, the ECU 24 operates the solenoid 32 to displace the regulating member 31 to the engagement position D1. Thereby, the rotation of the ring member 60 and the carrier 22 is restricted, and the revolution of the planetary gear 21 is restricted.

By restricting the revolution of the planetary gear 21, the transmission ratio between the first and second sun gears 19, 20, that is, the transmission ratio θ 2 / θ 1 is fixed. It should be noted that the restricting member 31 is located at the disengagement position D2 at a normal time that is not abnormal.
FIG. 2 is a cross-sectional view of a main part of FIG. Referring to FIG. 2, planetary gear mechanism 17 is housed in housing 36. The housing 36 is a cylindrical member made of aluminum alloy, for example, and is supported by the vehicle body 37.

The input shaft 5a of the first shaft 5 is rotatably supported by the housing 36 via a first bearing 38 made of a roller bearing or the like. The output shaft 5b is rotatably supported by the housing 36 via a second bearing 39 made of a rolling bearing such as a single row angular ball bearing.
The rotor 23a of the reaction force compensating motor 23 is fixed to the outer peripheral surface of the intermediate portion of the output shaft 5b. The stator 23 b of the reaction force compensating motor 23 is fixed to the housing 36.

An intermediate portion of the second shaft 6 is rotatably supported by the housing 36 via a third bearing 40 formed of a rolling bearing such as a single row angular ball bearing.
The first sun gear 19 of the planetary gear mechanism 17 is formed integrally with the output shaft 5b of the first shaft 5 using a single member, and is located at one end of the output shaft 5b. The second sun gear 20 is formed integrally with the second shaft 6 using a single member, and is positioned at one end of the second shaft 6.

Each planetary gear 21 has a tooth portion 21a that meshes with both the first and second sun gears 19 and 20, and support shafts 21b and 21c that extend from a pair of end portions of the tooth portion 21a.
3 is a cross-sectional view taken along line III-III in FIG. Referring to FIGS. 2 and 3, carrier 22 has one end 41 that supports one support shaft 21 b of each planetary gear 21, and the other end 42 that supports the other support shaft 21 c of each planetary gear 21. , And an intermediate portion 43 that connects between the one end portion 41 and the other end portion 42.

  One end 41 of the carrier 22 rotatably supports the output shaft 5b via a fourth bearing 44 made of a rolling bearing such as a roller bearing. An annular flange 45 that extends along the axial direction of the steering shaft 3 is formed at the one end 41. The flange portion 45 is rotatably supported by the housing 36 via a fifth bearing 46 formed of a rolling bearing such as a single row angular ball bearing.

Further, the one end portion 41 of the carrier 22 supports the one support shaft 21b of each planetary gear 21 via a corresponding sixth bearing 47 so as to be rotatable. Each sixth bearing 47 is composed of, for example, a roller bearing.
4 is a cross-sectional view taken along line IV-IV in FIG. 2 and 4, the other end portion 42 of the carrier 22 supports the second shaft 6 rotatably via a seventh bearing 48 formed of a rolling bearing such as a roller bearing. The other end portion 42 is formed with an annular flange portion 49 extending along the axial direction of the steering shaft 3. The flange portion 49 is rotatably supported by the housing 36 via an eighth bearing 50 made of a single row angular ball bearing or the like.

  Further, the other end portion 42 of the carrier 22 supports the other support shaft 21c of each planetary gear 21 via a corresponding ninth bearing 51 so as to be rotatable. Each 9th bearing 51 consists of roller bearings, for example. The intermediate portion 43 of the carrier 22 is arranged in the circumferential direction of the toothed portion 21 a of each planetary gear 21 and the steering shaft 3, and the one end portion 41 and the other end portion 42 can be rotated around the central axis of the carrier 22. Are connected.

The rotor 18 a of the planetary gear mechanism motor 18 is fixed to the outer peripheral surface of the other end portion 42 of the carrier 22. The stator 18b of the planetary gear mechanism motor 18 is fitted into the housing 36 and fixed.
A planetary gear mechanism motor resolver 33 is disposed adjacent to the rotor 18a of the planetary gear mechanism motor 18. The rotor 33a of the planetary gear mechanism motor resolver 33 is connected to the ring member 60 so as to be able to rotate along with the ring member 60, and rotates along with the rotor 18a of the planetary gear mechanism motor 18. The stator 33b of the planetary gear mechanism motor resolver 33 is fixedly fitted into the housing 36.

FIG. 5 is an enlarged view of a main part around the solenoid 32 of FIG. 6 is a cross-sectional view of a main part taken along line VI-VI in FIG.
With reference to FIG. 5, the solenoid 32 is disposed outward in the radial direction R of the carrier 22. The solenoid 32 includes a solenoid housing 52, a stator 34, a mover 54, a regulating member 31, and a coil spring 59 as an urging member.

The solenoid housing 52 has a bottomed cylindrical shape. A hollow screw shaft 52 a formed at one end of the solenoid housing 52 is screwed into and fixed to the screw hole 53 a of the holding hole 53 of the housing 36. The axis A of the solenoid housing 52 is inclined with respect to the radial direction R of the carrier 22.
The solenoid housing 52 accommodates the stator 34 and the movable element 54. By exciting the stator 34, a driving force along the axial direction of the solenoid housing 52 is applied to the mover 54. The movable element 54 is guided so as to be movable in a movable direction B along the axis A of the solenoid housing 52.

The regulating member 31 is formed in a rod shape using metal, for example. The regulating member 31 may be formed using a synthetic resin. One end 31 a of the restricting member 31 is fixed to one end 54 a of the mover 54 of the solenoid 32. The mover 54 and the regulating member 31 can move in the movable direction B.
The other end 31 b and the intermediate portion 31 c of the regulating member 31 protrude from the solenoid housing 52 and extend toward the carrier 22 side of the planetary gear mechanism 17. The other end 31 b of the restricting member 31 is inserted into the insertion hole 55 in the housing 36 that communicates the space 63 in which the carrier 22 is accommodated with the holding hole 53, and the flange 49 and the radial direction R of the carrier 22. Are opposed to each other.

  A flange portion 56 that projects in the radial direction of the intermediate portion 31 c is formed in the intermediate portion 31 c of the regulating member 31. The flange portion 56 has an annular shape, for example, and is received by one end surface of a bottomed cylindrical cup member 57 fitted to the intermediate portion 31c. The other end surface of the cup member 57 is received by one end surface 52 b of the solenoid housing 52 via a washer 58. When the cup member 57 receives the flange portion 56, the restriction member 31 is restricted from moving to one side B <b> 1 in the movable direction B.

A coil spring 59 is loosely fitted to the intermediate portion 31 c of the regulating member 31. The coil spring 59 is disposed between the other end of the cup member 57 and the flange portion 56 of the restriction member 31, and the restriction member 31 is engaged with the other B2 side in the movable direction B, that is, the restriction member 31 is engaged with the engagement position D1. It is energizing to the side.
During normal operation, a drive force toward the one side B <b> 1 in the movable direction B is applied to the mover 54 by energizing the solenoid 32. Thereby, the restricting member 31 compresses the coil spring 59 against the urging force of the coil spring 59, and the flange portion 56 is received by the cup member 57. At this time, the regulating member 31 is located at the engagement release position D2.

5 and 6, the ring member 60 is disposed adjacent to the eighth bearing 50 and is fixed to the outer peripheral surface of the annular flange portion 49 of the carrier 22 by, for example, press-fitting. The carrier 22 and the ring member 60 may be integrally formed using a single member.
On the outer peripheral surface 60 a of the ring member 60, an engaging recess 61 that can be engaged with the other end 31 b of the regulating member 31 is formed. A plurality of engaging recesses 61 (eight in the present embodiment, for example) are provided at equal intervals in the circumferential direction C of the outer peripheral surface 60a.

When restricting the rotation of the carrier 22, the ECU 24 interrupts the supply of power to the solenoid 32. As a result, the magnetic coupling between the mover 54 and the stator 34 of the solenoid 32 is released, and as a result, the regulating member 31 is moved to the other B2 side (engagement position) in the movable direction B by the biasing force of the coil spring 59. D1 side).
As shown in FIG. 7, the other end 31b of the restricting member 31 engages with the engaging recess 61, and the rotation of the ring member 60 and the carrier 22 is restricted.

FIG. 8 is a block diagram showing the main part of the electrical configuration of the vehicle steering apparatus 1. Referring to FIG. 8, ECU 24 includes a first abnormality detection unit 71 as a first abnormality detection unit, a second abnormality detection unit 72 as a second abnormality detection unit, and a planet as a motor control unit. A gear mechanism motor control unit 73 and a lock control unit 74 as lock control means are included.
The first abnormality detection unit 71 detects an abnormality in the output of the transmission ratio variable mechanism 8. The first abnormality detection unit 71 is connected to the turning angle sensor 28 and the planetary gear mechanism motor control unit 73, and a signal related to the turning angle θ2 and a target rotational speed dθ2 _t described later of the second shaft 6. A signal related to / dt is input.

The second abnormality detector 72 detects an abnormality of the planetary gear mechanism 17. The second abnormality detection unit 72 is connected to each of the steering angle sensor 26, the turning angle sensor 28, and the planetary gear mechanism motor control unit 73, and the steering angle θ1, the turning angle θ2, and a target described later. Signals relating to the transmission ratio θ2 _t / θ1 _t are input. Further, the second abnormality detection unit 72 is connected to the first abnormality detection unit 71, and an abnormality detection signal of the first abnormality detection unit 71 is input.

  The planetary gear mechanism motor control unit 73 controls the driving of the planetary gear mechanism motor 18. The planetary gear mechanism motor control unit 73 is connected to each of the steering angle sensor 26, the turning angle sensor 28, the planetary gear mechanism motor resolver 33, the torque sensor 27, the vehicle speed sensor 29, and the yaw rate sensor 30. The planetary gear mechanism motor controller 73 receives signals related to the steering angle θ1, the turning angle θ2, the rotation angle θm of the rotor 18a of the planetary gear mechanism motor 18, the steering torque T, the vehicle speed V, and the yaw rate γ. It is like that.

Planetary gear mechanism motor controller 73 based on these signals, and the target revolution speed d? 1 _t / dt of the output shaft 5b of the first shaft 5, Ya target speed d? 2 _t / dt of the second shaft 6 The target transmission ratio θ2 _t / θ1 _t is set as the target value of the transmission ratio θ2 / θ1. The planetary gear mechanism motor control unit 73 controls driving of the planetary gear mechanism motor 18 based on the target transmission ratio θ2 _t / θ1 _t .

The planetary gear mechanism motor control unit 73 is connected to each of the first abnormality detection unit 71 and the lock control unit 74, and the abnormality detection signal of the first abnormality detection unit 71 and the lock control unit 74. Signals relating to operating states are input respectively.
The lock control unit 74 controls the operation of the solenoid 32. The lock control unit 74 is connected to the first abnormality detection unit 71 and the second abnormality detection unit 72, and the abnormality detection signal of the first abnormality detection unit 71 and the abnormality detection signal of the second abnormality detection unit 72. Each is entered.

One of the features of the present embodiment is that when an abnormality (failure) occurs in the vehicle steering device 1, the ECU 24 controls the steering member 2 and the second shaft 6 without impairing the steering feeling. It is in the point which connects so that torque transmission is possible.
FIG. 9 is a flowchart of an example of control related to an abnormality in the vehicle steering apparatus 1. Referring to FIG. 9, first, the first abnormality detection unit 71 of the ECU 24 determines whether or not a first abnormality has occurred (step S1). The first abnormality refers to an abnormality in the output of the transmission ratio variable mechanism 8. For example, when the planetary gear mechanism motor 18 runs out of control, the rotational speed dθ2 / dt (rotational speed) of the second shaft 6 is This means that the rotational speed greatly deviates from the target rotational speed dθ2 _t / dt.

When the deviation of the rotation speed dθ2 / dt of the second shaft 6 with respect to the target rotation speed dθ2 _t / dt of the second shaft 6 obtained by the planetary gear mechanism motor control unit 73 is equal to or greater than a predetermined value α1 ( | Dθ2 _t / dt−dθ2 / dt | ≧ α1), the first abnormality detector 71 detects the first abnormality.
When the first abnormality is detected (YES in step S1), the second abnormality detection unit 72 determines whether or not the second abnormality has occurred (step S2).

  The second abnormality is an abnormality of the planetary gear mechanism 17. Specifically, at least one of the meshing portion between the planetary gear 21 and the first sun gear 19 and the meshing portion between the planetary gear 21 and the second sun gear 20 is caused by the meshing resistance due to mixing of foreign matters such as iron powder. It means that the gears 19, 20, and 21 are locked due to the increase of the rotation, the mixing of foreign matter, seizure, and the deformation of teeth.

When the second abnormality occurs, the gears 19, 20, and 21 are locked with each other or close to being locked. Therefore, the output shaft 5b of the first shaft 5 and the second shaft 6 are directly connected or substantially directly connected, and the transmission ratio θ2 / θ1 is substantially 1.
The detected transmission ratio θ2 / θ1 (actual transmission ratio) is approximately 1, and the target transmission ratio θ2 _t / θ1 _t set by the planetary gear mechanism motor control unit 73 with respect to the transmission ratio θ2 / θ1. of the deviation _{| θ2 / θ1-θ2 t /} θ1 t | is a predetermined value [alpha] 2 (e.g., 0.2) or more when it is (| | θ2 / θ1-θ2 t / θ1 t ≧ α2), the second abnormality detection Unit 72 detects the second abnormality (YES in step S2).

As an example, when the transmission ratio θ2 / θ1 is 1 and the target transmission ratio θ2 _t / θ1 _t is 1.5, the second abnormality detection unit 72 assumes that the deviation is 0.5. Detects the second abnormality. Note that the second abnormality may be detected when the transmission ratio θ2 / θ1 is approximately 1, regardless of the target transmission ratio θ2 _t / θ1 _t .
When the second abnormality is detected, the lock control unit 74 prohibits the carrier 22 from being locked by the regulating member 31 of the solenoid 32 (step S3). That is, the mover 54 and the regulating member 31 of the solenoid 32 are prohibited from being displaced from the disengagement position D2. Thereby, the carrier 22 is maintained in a rotatable state.

  On the other hand, when the second abnormality detection unit 72 does not detect the second abnormality (NO in step S2), there is no abnormality in the meshing state between the planetary gear 21 and the first and second sun gears 19 and 20, and the planetary gear. No abnormality has occurred in the mechanism 17. At this time, the carrier 22 is locked (step S4). Specifically, the lock control unit 74 stops energization of the solenoid 32. As a result, the magnetic coupling between the stator 34 and the movable element 54 of the solenoid 32 is released. As a result, the coil spring 59 is extended, and the restricting member 31 is displaced from the engagement release position D1 to the engagement position D2. The restricting member 31 displaced to the engaging position D <b> 2 engages with the engaging recess 61 of the ring member 60 and restricts the rotation of the ring member 60 and the carrier 22.

  After locking of the carrier 22 by the solenoid 32 is prohibited (step S3) or after the carrier 22 is locked by the solenoid 32 (step S4), the planetary gear mechanism motor 18 is controlled by the planetary gear mechanism motor control unit 73. The drive is turned off (step S5). Specifically, energization of the planetary gear mechanism motor 18 is stopped by turning off a relay (not shown).

As described above, according to the present embodiment, when an abnormality in the output of the transmission ratio variable mechanism 8 is detected by the first abnormality detection unit 71, the steering member 2 and the first member are not damaged without impairing the steering feeling. The two shafts 6 can be coupled so as to be able to transmit torque.
Specifically, when the abnormality of the output of the transmission ratio variable mechanism 8 is detected by the first abnormality detection unit 71, the condition is that the abnormality of the planetary gear mechanism 17 is detected by the second abnormality detection unit 72. As a result, the carrier 22 is locked. At this time, even if the carrier 22 is not locked, the planetary gear 21, the first sun gear 19, and the second sun gear 20 are locked or can transmit torque in a state close to the lock. Therefore, the first sun gear 19 and the second sun gear 20 can transmit torque at a substantially constant transmission ratio θ2 / θ1, and the steering member 2 and the second shaft 6 can transmit torque. At this time, since the carrier 22 is not locked, the steering member 2 can be operated with a relatively small torque.

  Further, the carrier 22 is locked on condition that no abnormality of the planetary gear mechanism 17 is detected by the second abnormality detection unit 72. At this time, since the driving resistance between the planetary gear 21 and the first sun gear 19 and the second sun gear 20 remains small, the gears 19, 20, and 21 can mesh smoothly. When carrier 22 is locked in this state, torque can be transmitted between first sun gear 19 and second sun gear 20 at a constant transmission ratio θ2 / θ1. As a result, the steering member 2 can be operated with a relatively small torque.

Thus, even when the first abnormality (abnormality of the transmission ratio variable mechanism 8) occurs, the steering member 2 can be operated with a relatively small torque, so that the steering feeling during a failure can be improved.
When the first abnormality is detected, the transmission member variable mechanism motor 18 is stopped while the steering member 2 and the second shaft 6 are connected so as to be able to transmit torque. Therefore, the planetary gear mechanism motor 18 can be stopped while maintaining a state in which the steered wheels 4L and 4R can be steered by the operation of the steering member 2.

Further, the second abnormality detection unit 72 is configured to detect the planetary gear when the deviation | θ2 _t / θ1 _t −θ2 / θ1 | between the target transmission ratio θ2 _t / θ1 _t and the transmission ratio θ2 / θ1 is equal to or greater than a predetermined value α2. An abnormality of the mechanism 17 is detected. By such an abnormality detection method, an increase in driving resistance or locking due to foreign object biting or the like occurs between at least one of the first sun gear 19 and the second sun gear 20 and the planetary gear 21. As a result, the abnormality of the planetary gear mechanism 17 can be reliably detected.

The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims.
For example, instead of the solenoid 32, another mechanism such as a hydraulic cylinder or a cam mechanism may be used as the lock mechanism. Further, as the planetary transmission mechanism, a traction drive mechanism using a roller instead of each gear of the planetary gear mechanism 17 may be used.

Alternatively, a warning lamp may be turned on when the first abnormality is detected to prompt the driver to repair.
Furthermore, the configuration for detecting the second abnormality is not limited to that described above. In short, any configuration may be used as long as the meshing resistance is increased or the locked state is detected between the planetary gear 21 and at least one of the first and second sun gears 19 and 20.

DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 6 ... 2nd shaft (steering wheel side member), 8 ... Transmission ratio variable mechanism, 17 ... Planetary gear mechanism (differential mechanism), 18 ... Motor for planetary gear mechanism (Transmission ratio variable mechanism motor), 19 ... first sun gear (input element), 20 ... second sun gear (output element), 21 ... planet gear (planet element), 22 ... carrier, 32 ... solenoid (lock mechanism) , 71 ... 1st abnormality detection part (1st abnormality detection means), 72 ... 2nd abnormality detection part (2nd abnormality detection means), 73 ... Motor control part (motor control means) for planetary gear mechanisms , 74 ... Lock control unit (lock control means), θ1 ... Steering angle (rotation angle of steering member), θ2 ... Steering angle (rotation angle of steered wheel side member), θ2 / θ1 ... Transmission ratio (actual transmission ratio) , Θ2 _t / θ1 _t ... target transmission ratio, | θ2 _t / θ1 _t −θ2 / θ1 | Difference, α2 ... predetermined value.

Claims (1)

An input element connected to the steering member, an output element connected to the steered wheel side member, a planetary element interposed between the input element and the output element, a differential mechanism including a carrier supporting the planetary element, and a transmission ratio variable mechanism motor A transmission ratio variable mechanism capable of changing a transmission ratio that is a ratio of the rotation angle of the steered wheel side member to the rotation angle of the steering member;
Motor control means for controlling the transmission ratio variable mechanism motor based on a target transmission ratio;
A locking mechanism capable of locking the carrier;
First abnormality detection means for detecting an abnormality in the output of the transmission ratio variable mechanism;
A second abnormality detecting means for detecting an abnormality of the differential mechanism when a deviation between the target transmission ratio and the actual transmission ratio is a predetermined value or more ;
Lock control means for controlling the operation of the lock mechanism,
The abnormality in the output of the transmission ratio variable mechanism is that the rotational speed of the output element deviates from a target rotational speed by a predetermined value or more.
The abnormality of the differential mechanism is that the driving resistance between the planetary element and at least one of the input element and the output element is increased, or these three elements are locked,
The lock control means detects that an abnormality of the differential mechanism is detected by the second abnormality detection means when an abnormality of the output of the transmission ratio variable mechanism is detected by the first abnormality detection means. As a condition, the carrier is locked by the lock mechanism, and the carrier is locked by the lock mechanism on condition that the second abnormality detection means does not detect an abnormality of the differential mechanism ,
It said motor control means, steering the vehicle, characterized that you stop the driving of the motor for the transmission ratio variable mechanism when the abnormality of the output of the transmission ratio variable mechanism is detected by the first abnormality detecting means apparatus.

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