JP2005162111A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle capable of miniaturizing a lock mechanism. <P>SOLUTION: The steering device 10 for the vehicle comprises an input shaft transmitting a torque of a steering wheel 11, an output shaft transmitting the torque to the steering gears 17, 18, a transmission ratio variable mechanism 30 changing the transmission ratio between the input shaft and the output shaft by the driving of an electric motor 34, a lock holder 36 which is provided on the rotating shaft 35 of the electric motor 34 and has an recessed part 37, and a lock lever 52 movable between a locking position which is supported on the housing 32 unrotatable to the vehicle body, equipped with an engaging part 52a engageable with the recessed part 37 of the lock holder 36, and in which the engaging part 52a can move between a lock position where the engaging part 52a engages with the recessed part 37 of the lock holder 36, and an unlock position where the engaging part 52a is separated from the recessed part 37. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle steering apparatus including a transmission ratio variable mechanism having a lock mechanism.

Conventionally, a transmission ratio variable mechanism for variably controlling a ratio of a tire turning angle to a steering angle of a steering wheel is widely known. In this type of transmission ratio variable mechanism, a technique having a lock mechanism therein is known (see, for example, Patent Document 1). This locking mechanism locks the differential mechanism of the transmission ratio variable mechanism by engaging the lock arm with the lock holder under a predetermined situation, and ensures the steering when the system is defective or the power is turned off. Fulfill.
JP 2001-48032 A

  However, in a configuration in which the lock mechanism rotates with the rotation of the steering wheel (i.e., a configuration in which the lock arm is supported by the motor housing that rotates with the rotation of the steering wheel), the lock mechanism rotates over the entire circumference of the shaft. In order to ensure reliability, the urging force for urging the lock arm toward the lock holder and the driving force for moving the lock arm to the unlock position must be increased, and the lock mechanism can be made compact. It was an obstacle to becoming.

  Therefore, an object of the present invention is to provide a vehicle steering apparatus that can reduce the size of a lock mechanism.

In order to solve the above problems, according to one aspect of the present invention,
An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A rotating member provided on the rotating shaft of the electric motor and having an engaged portion;
A lock position that is supported by a portion that cannot rotate with respect to the vehicle body and that can be engaged with the engaged portion of the rotating member, and the engaging portion engages with the engaged portion of the rotating member; There is provided a vehicle steering apparatus including a rotation restricting member that is movable between an unlocking position in which a joint portion is separated from an engaged portion.

  In this aspect, the rotation member is preferably provided around the rotation axis of the electric motor. In this case, the rotating member may be a member that is press-fitted and fixed around the rotating shaft of the electric motor, or may be integrally formed on the rotating shaft of the electric motor. The rotating member may be provided on another rotating member on the rotating shaft of the electric motor. That is, the rotating member may be a member that rotates with the rotation of the rotating shaft of the electric motor. In this aspect, when the engaging part of the rotation restricting member is engaged with the engaged part of the rotating member, the rotation shaft of the electric motor cannot be rotated.

  The rotation restricting member is preferably supported by a housing that houses the transmission ratio variable mechanism as a portion that cannot rotate with respect to the vehicle body. For example, the housing may be supported by the suspension member via a rubber bush or the like. The housing may also accommodate a steering gear or the like.

  Effectively, the rotation restricting member has a moving direction from the locked position to the unlocked position, in particular, an initial moving direction (that is, a moving direction when starting from the locked position to the unlocked position) is the vehicle vertical direction. Is arranged so as not to coincide with the direction of vibration input from the vehicle or to substantially correspond to the left-right direction of the vehicle.

  According to the present invention, it is possible to reduce the size of the lock mechanism.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall view schematically showing an embodiment of a vehicle steering apparatus according to the present invention. The vehicle steering apparatus 10 includes a steering column 12 including a steering wheel 11 operated by a driver. The steering column 12 rotatably supports a main shaft 14 that serves as a rotating shaft of the steering wheel 11. The main shaft 14 is connected to an intermediate shaft (intermediate shaft) 16 via a rubber coupling 13 or the like. The intermediate shaft 16 is connected to a steering gear box 31, and the pinion 17 is engaged with the steering rack 18 in the steering gear box 31. One end of a tie rod 19 is connected to each end of the steering rack 18 and a steered wheel (not shown) is connected to the other end of each tie rod 19 via a knuckle arm or the like (not shown).

  The intermediate shaft 16 or the main shaft 14 has a steering angle sensor (not shown) that generates a signal corresponding to the steering angle of the steering wheel 11, or a torque sensor that generates a signal corresponding to the steering torque generated in the steering shaft. 15 is provided. In the steering gear box 31, an assist motor 20 for assisting steering is provided coaxially with the rack shaft. The assist motor 20 may be provided in the steering column 12 or on the pinion shaft.

  The vehicle steering apparatus 10 further includes a transmission ratio variable mechanism 30 in the steering gear box 31. The transmission ratio variable mechanism 30 has a function of varying the ratio (gear ratio) of the tire turning angle to the steering angle of the steering wheel 11 according to, for example, the vehicle speed.

FIG. 2 is a cross-sectional view of the transmission ratio variable mechanism 30 when cut along the plane including the shaft axis, and FIG. 3 is an explanatory diagram of the transmission ratio variable principle of the transmission ratio variable mechanism 30. The transmission ratio variable mechanism 30 includes a housing 32. The housing 32 is an integral housing with the steering gear box 31, and is supported by a suspension member (not shown) or the like. The housing 32 may be separate from the housing of the steering gear box 31.
In the housing 32, an input shaft 60, an output shaft 62, a reduction gear (differential mechanism) 40, a motor 34 (DC brushless motor), and a lock mechanism 50 are accommodated. The speed reducer 40 includes a driven gear 38, a stator gear 42, a wave generator 46, and a flexible gear 48, as will be described later.

  The lower end of the intermediate shaft 16 is connected to the upper end of the input shaft 60. A stator gear 42 is provided at the lower end of the input shaft 60. A pinion 17 is provided below the output shaft 62. A driven gear 38 is provided above the output shaft 62. Gears having different numbers of teeth (the number of teeth of the driven gear 38 <the number of teeth of the stator gear 42) are formed on the inner peripheral surfaces of the driven gear 38 and the stator gear 42, respectively. Inside the driven gear 38 and the stator gear 42, a flexible gear 48 that meshes simultaneously with each gear is provided. That is, the teeth formed inside the driven gear 38 and the stator gear 42 mesh with the teeth formed outside the flexible gear 48 (the number of teeth is the same as the number of teeth of the driven gear 38). The inner side of the flexible gear 48 is fitted on the outer ring of the wave generator 46.

  A case 34 a of a motor 34 is fixed to the housing 32. The motor 34 has a motor shaft 35, and the motor shaft 35 is connected to the cam of the wave generator 46. An input shaft 60 is rotatably inserted into the motor shaft 35. That is, the input shaft 60 and the motor shaft 35 are configured to be able to rotate independently of each other.

  In this configuration, as shown in FIG. 3, when the motor shaft 35 of the motor 34 rotates, the cam of the wave generator 46 rotates and the flexible gear 48 rotates. At this time, the flexible gear 48 rotates in the stator gear 42 in a state of being deformed into an elliptical shape, and rotates the driven gear 38 on the same axis. That is, since the number of teeth of the driven gear 38 is smaller than the number of teeth of the stator gear 42, when the wave generator 46 rotates once, the driven gear 38 rotates by the difference in the number of teeth in the direction opposite to the rotation direction of the wave generator 46. (That is, actuator operating angle = rotation angle of motor 34 × reduction ratio (reduction ratio = number of teeth difference / number of teeth of driven gear 38)). On the other hand, when the steering wheel 11 (main shaft 14) rotates, the input shaft 60 (stator gear 42) rotates, and an actuator operating angle is added and transmitted to the output shaft 62.

  4 is a cross-sectional view of the locking mechanism 50 cut along line AA in FIG. The lock mechanism 50 is mounted around the motor shaft 35 of the motor 34. The lock mechanism 50 includes a lock lever (lock arm) 52 that can rotate around the rotation pin 54. The rotation pin 54 is fixed to the housing 32 of the transmission ratio variable mechanism 30. As a result, the lock lever 52 is supported at a portion that cannot rotate with respect to the vehicle body such as the housing 32. At the tip of the lock lever 52, an engaging portion 52a that engages with a concave portion 37 of the lock holder 36 described later is provided.

  A substantially ring-shaped lock holder 36 is provided on the motor shaft 35 of the motor 34. The lock holder 36 is provided so as not to rotate with respect to the motor shaft 35 so as to rotate together with the motor shaft 35. On the outer periphery of the lock holder 36, a recess 37 is formed in which the engaging portion 52a of the lock lever 52 is engaged. As shown in FIG. 4, a plurality of recesses 37 are set at predetermined intervals in the circumferential direction, and each of the recesses 37 is substantially open radially outward.

  The lock lever 52 is urged toward the lock holder 36 by a return spring 53 provided around the rotation pin 54. In other words, the return spring 53 urges the lock lever 52 so that the engaging portion 52 a of the lock lever 52 is radially inserted into the recess 37 of the lock holder 36. When the engagement portion 52 a of the lock lever 52 is fitted into the recess 37, the lock lever 52 is held in the recess 37 by the elastic force of the return spring 53. Thereby, a locked state is implement | achieved (refer FIG. 5 (A)).

  When the locked state is realized, the motor shaft 35 of the motor 34 is fixed to the housing 32 of the transmission ratio variable mechanism 30 by the engagement of the lock lever 52 and the lock holder 36. That is, the rotation of the motor shaft 35 of the motor 34 is locked by the engagement portion 52a of the lock lever 52 fitted in the recess 37 of the lock holder 36, and cannot be rotated with respect to the housing 32 (vehicle body). It becomes a state. In this case, even if the motor 34 is driven, the motor shaft 35 does not rotate. On the other hand, when the steering wheel 11 rotates, the input shaft 60 (stator gear 42) rotates, and the driven gear 38 rotates through the flexible gear 48. At this time, a rotational reaction force is transmitted to the motor shaft 35 via the flexible gear 48. However, since the motor shaft 35 is in a non-rotatable state by the lock lever 52, the motor shaft 35 is not rotated. It is not rotated by force (that is, the rotation of the steering wheel 11 is reliably transmitted to the steered wheels even in the locked state). Thus, the lock mechanism 50 plays a role of ensuring steering when the system is defective or the power is turned off.

  The lock mechanism 50 of this embodiment is electromagnetically operated by a solenoid 56 that is a drive source. For example, when the solenoid 56 is energized when the ignition is on (when the system is normal), the lock lever 52 rotates against the urging force from the return spring 53 by the suction force generated by the solenoid 56, and the lock lever 52 The engaging portion 52 a is detached from the recess 37 of the lock holder 36. Thereby, the unlocked state is realized (see FIG. 5B). When the unlocked state is realized, the motor shaft 35 of the motor 34 rotates when the motor 34 is driven, and the transmission ratio variable function is realized as described above. On the other hand, when the system is defective or the power is turned off (ignition switch off), the energization to the solenoid 56 is cut off, and the operation of the lock mechanism 50 is realized as described above. Note that control of the lock mechanism 50 (that is, switching control between the locked state and the unlocked state) may be realized by an ECU (for example, an electronic control device for variable transmission ratio control).

  By the way, a large vertical acceleration (acceleration component in the vertical plane) acts on the actual vehicle steering device 10 when traveling on a rough road or over a step. Further, the vehicle steering device 10 is not as large as vertical acceleration, but lateral (left-right) acceleration (acceleration component in a horizontal plane) also acts when rolling or turning. Also in the transmission ratio variable mechanism 30, the motor shaft 35 of the motor 34 is not substantially in the vertical direction in the actual mounted state. Therefore, the radial component of the lateral acceleration and the vertical acceleration acting on the vehicle steering device 10 acts in the radial direction of the motor shaft 35 of the motor 34, and the magnitude thereof is the circumference of the motor shaft 35. Different in each of the above points.

  Therefore, the engagement position of the engagement portion 52a of the lock lever 52 with the lock holder 36 is changed in an absolute coordinate system (a coordinate system composed of a vertical axis and two axes in a horizontal plane), that is, the engagement position is the steering. In the configuration that can be changed with the rotation of the wheel 11 (for example, the configuration as in the above-described conventional technology), the return spring is considered in consideration of the influence of the acceleration applied to the vehicle steering device 10 over the entire circumference of the motor shaft 35. The urging force 53 and the suction force of the solenoid 56 must be increased.

  On the other hand, in this embodiment, the lock lever 52 is supported so as not to rotate with respect to the vehicle body, so that the engagement position of the engagement portion 52a of the lock lever 52 with the lock holder 36 is an absolute coordinate system. It does not change. Therefore, according to the present embodiment, it is only necessary to consider the influence of various accelerations received by the vehicle steering apparatus 10 at the fixed engagement position. That is, according to the present embodiment, it is easy to set an appropriate biasing force of the return spring 53 and an attractive force of the solenoid 56 (for example, even when the acceleration sensor is experimentally installed at the engagement position) One installation point is enough).

  Next, with reference to FIG. 6, a preferred engagement position between the engagement portion 52a of the lock lever 52 and the lock holder 36 will be described.

  FIG. 6 shows an absolute coordinate system including an X axis (vehicle longitudinal direction), a Y axis (vehicle width direction), and a Z axis (vertical axis). FIG. 6 shows a local coordinate system (x, y, z) having a certain reference point o on the motor shaft 35 (for example, a point in the plane of the lock holder 36) as the origin and the motor shaft axis as the z axis. It is shown. It is assumed that the motor shaft in the vehicle mounted state is inclined at the angles φ and λ shown in FIG. 6 in the absolute coordinate system (the angles φ and λ are known from the mounted state). Here, it is assumed that the acceleration (0, Y1, Z1) acts on the reference point o in the transmission ratio variable mechanism 30 in the absolute coordinate system. In this case, the acceleration α = (αx, αy, αz) of the local coordinate system at the reference point o on the motor shaft 35 is given by the following equation.

Here, each acceleration component affecting the release of the lock lever 52 is (αx, αy) = (Y1 × −sinφ · sinλ + Z1 × cosλ, Y1 × cosλ). Therefore, when the acceleration vector (αx, αy) matches the direction in which the lock lever 52 is disengaged (that is, the direction in which the engaging portion 52a is disengaged), the lock lever 52 is most disengaged from the recess 37 of the lock holder 36. It becomes easy.

  For this reason, the engagement position of the lock lever 52 of the present embodiment is set in a direction in which the release direction of the lock lever 52 does not match the acceleration vector (αx, αy).

  Further, in addition to the case where the acceleration (0, Y1, Z1) acts on the reference point o, the acceleration (0, -Y1, -Z2) occurs when the acceleration (0, -Y1, Z1) acts on the reference point o. Similarly, when the acceleration (0, Y1, -Z2) acts on the reference point o when acting on the reference point o, the acceleration vectors (total four acceleration vectors) in the local coordinate system are determined. Also good. In this case, the engagement position of the lock lever 52 of the present embodiment is set in a direction in which the release direction of the lock lever 52 does not match each acceleration vector, and preferably, the angle formed by two adjacent acceleration vectors is equally divided. It is set so that the direction in which the lock lever 52 is released coincides with the direction.

  The assumed acceleration (0, Y1, Z1) may be a value based on an actual vehicle test result, an analysis result, or the like (for example, a combination of acceleration components that can be generated at the same time based on the test result). Further, in the present embodiment, only the vertical acceleration may be considered in consideration that the lateral (left / right) acceleration is not as large as the vertical acceleration (that is, Y1 = 0). Further, longitudinal acceleration may be taken into account (that is, assumed acceleration (X1, Y1, Z1)).

  Alternatively, the vertical axis (Z-axis in FIG. 6) and the left-right axis (on the cross-section (see FIG. 4) when cut in a plane perpendicular to the shaft axis of the transmission ratio variable mechanism 30 in the mounted state ( For example, the direction in which the lock lever 52 is released is substantially the same as the direction of the projected left and right axis so that the direction of the release of the lock lever 52 does not coincide with the direction of the projected vertical axis. An engagement position between the lock lever 52 and the lock holder 36 may be set so as to correspond.

  As described above, according to this embodiment, the absolute engagement position of the lock lever 52 can be appropriately set at a position where the influence of various accelerations received by the vehicle steering apparatus 10 is the smallest. Thereby, the urging force of the return spring 53 can be set small, and accordingly, the suction force of the solenoid 56 can be set small. As a result, it is possible to reduce the size of the transmission ratio variable mechanism 30 and reduce the power consumption of the drive source (solenoid 56).

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the drive of the lock mechanism 50 (rotation of the lock lever 52) is realized using the electromagnetic force generated by the solenoid, but the drive of the lock mechanism 50 is performed by hydraulic pressure or rotation of the motor. You may implement | achieve using a torque.

  Further, in the above-described embodiment, the engaging portion 52 a of the lock lever 52 does not necessarily have to be rotated around the motor shaft 35 when being inserted into the recess 37 of the lock holder 36. Further, as shown in FIG. 5 and the like, the recess 37 of the lock holder 36 may be inclined so as not to hinder the rotational movement of the engaging portion 52a of the lock lever 52.

  In the above-described embodiment, the locked state or the unlocked state is realized by the rotation of the lock lever 52, but the locked state or the unlocked state is changed by the linear movement of the lock lever 52 (that is, the reciprocating motion). It may be realized. In this case, the reciprocating direction of the lock lever 52 may be set to an appropriate direction as in the above-described embodiment.

1 is an overall view schematically showing an embodiment of a vehicle steering apparatus according to the present invention. 3 is a sectional view of a transmission ratio variable mechanism 30. FIG. It is explanatory drawing of the transmission ratio variable principle by the transmission ratio variable mechanism. 3 is a cross-sectional view showing a lock mechanism 50. FIG. FIG. 10 is an operation explanatory diagram of the lock mechanism 50. It is explanatory drawing of the engagement position of the lock lever 52 of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle steering device 11 Steering wheel 12 Steering column 14 Main shaft 16 Intermediate shaft 17 Pinion 18 Steering rack 30 Transmission ratio variable mechanism 31 Steering gear box 32 Housing 34 Motor 35 Motor shaft 36 Lock holder 40 Reducer 37 Recess 50 Lock mechanism 52 Lock lever 52a Engagement part 53 Return spring 56 Solenoid 60 Input shaft 62 Output shaft

Claims (4)

An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A rotating member provided on the rotating shaft of the electric motor and having an engaged portion;
A lock position that is supported by a portion that cannot rotate with respect to the vehicle body and that can be engaged with the engaged portion of the rotating member, and the engaging portion engages with the engaged portion of the rotating member; A vehicle steering apparatus, comprising: a rotation restricting member that is movable between an unlocking position where the joint portion is separated from the engaged portion.   The vehicle steering apparatus according to claim 1, wherein the rotation restricting member is supported by a housing that houses the transmission ratio variable mechanism.   The vehicle steering apparatus according to claim 1 or 2, wherein the rotation restricting member is disposed such that a moving direction from the locked position toward the unlocked position does not coincide with a direction of vibration input from the vehicle vertical direction. .   The vehicle steering according to any one of claims 1 to 3, wherein the rotation restricting member is disposed such that a moving direction from the locked position toward the unlocked position substantially corresponds to a left-right direction of the vehicle. apparatus.