JP2005067429A - Vehicle steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering control device capable of improving the rotation transmission efficiency from an input shaft to an output shaft by increasing the support rigidity of the planetary gear.
A planetary gear mechanism is composed of first and second planetary gear units arranged at the front and rear, and first and second planetary gears 22 and 27 supported by a planetary carrier 21, and each planetary gear. And first and second ring gears 23 and 29 meshing with each other. Both planetary gears are rotatably supported by first and second bearings 47 and 48, respectively, on which a carrier body 38 disposed therebetween is provided on the inner peripheral surface and the outer peripheral surface of the extending portion 46 of the first ring gear. As a result, the support rigidity is increased and the radial positioning is ensured.
[Selection] Figure 1

Description

  The present invention relates to a vehicle steering control device, and more particularly to a steering control device capable of varying a reduction ratio between a steering wheel and a front wheel steering drive mechanism.

  As a conventional vehicle steering control device, for example, there is one described in Japanese Patent Application No. 2003-111113 filed earlier by the present applicant.

  The steering control device drives a first hydraulic power cylinder according to a steering angle of a steering shaft having a steering wheel attached to one end thereof, and drives a second power cylinder according to the steering angle of the steering shaft. Backup means. The backup means includes a planetary gear mechanism capable of changing the rotation ratio by directly transmitting the rotational torque of the steering shaft, and a gear pump that is rotationally driven by the rotational force transmitted from the planetary gear mechanism to the output shaft. The second power cylinder is operated by the hydraulic pressure fed from the gear pump to steer the steered wheels.

  In this planetary gear mechanism, a first planetary gear unit that is set to a predetermined reduction ratio (rotation ratio) divided forward and backward in a housing and a second planetary gear unit that is linked to the first planetary gear unit They are arranged in parallel. Each planetary gear unit includes first and second sun gears respectively connected to a steering shaft and an output shaft, first and second ring gears arranged on the outer peripheral side of each sun gear, and each ring gear. There are four first and second planetary gears arranged in the circumferential direction and meshing with the respective gears, and planetary carriers that link the planetary gears in the axial direction. This planetary carrier includes four spindles that rotatably support the first and second planetary gears in a coaxial manner, and two disk-like disks that are arranged outside the planetary gears and connect the spindles. And a support plate.

  When the steering wheel is rotated, the electronic controller that detects the steering angle and the actual turning angle outputs a control signal to the drive motor of the steering means, and the first hydraulic power via the predetermined gear mechanism. The hydraulic pressure in the cylinder is controlled to control the steering of the steered wheels.

  At this time, the first planetary gear unit controls the rotation of the first ring gear by a variable motor (electric motor), and changes the reduction ratio via the second planetary gear and the second sun gear of the second planetary gear unit. By adjusting the rotational phase difference between the steering shaft and the output shaft, an optimum steering reaction force characteristic is ensured.

On the other hand, for example, when the drive motor or the like is locked due to a failure, the steering shaft is rotated by the rotation of the steering wheel to rotate the first sun gear of the first planetary gear unit, and the first planetary gear unit is rotated. When the gear is rotated (revolved), the second planetary gear rotates synchronously (revolves) via the planetary carrier to rotate the second sun gear. As a result, the output shaft is rotationally driven at a one-to-one rotation ratio with the steering shaft, so that the gear pump rotates and controls the hydraulic pressure in the second power cylinder to manually control the steering wheel. It has become.
Japanese Patent Laid-Open No. 2002-296331

  However, in the conventional vehicle steering control device, the planetary carrier that supports the first and second planetary gears is simply inserted between the two outer support plates and the support plates, and the shaft of the output shaft. Since it is constituted by four support shafts connected in the direction, sufficient support rigidity between the planetary gears cannot be obtained.

  In particular, since the support rigidity in the rotation direction becomes insufficient, not only the rotation transmission efficiency from the first planetary gear to the second planetary gear is reduced, but also there is a possibility that abnormal noise may be generated during the rotation. There is a risk of lowering.

  The present invention has been devised in view of the technical problem of the conventional vehicle steering control device, and the invention according to claim 1 is characterized in that, in particular, the planetary gear mechanism is fixed to the steering shaft and arranged on the outer periphery. A planetary gear that meshes with a sun gear on which outer teeth are formed, a ring gear that is provided coaxially with the sun gear and that has inner teeth on the inner periphery, and the outer teeth of the sun gear and the inner teeth of the ring gear. A planetary gear supported so as to be able to revolve through a carrier, forming a cylindrical extension portion extending in the axial direction on the inner edge of the ring gear, and connecting the planetary carrier to the extension portion. It is characterized by being rotatably supported by a bearing held on the inner peripheral surface.

  According to this invention, since the planetary carrier is supported by the annular bearing disposed on the inner peripheral surface of the extending portion of the ring gear, the support rigidity of each planetary gear is increased. In particular, since the outer peripheral surface of the planetary carrier is supported by the bearing in the holding state, the radial support rigidity is increased, and a smooth rotating action of each planetary gear can be obtained at all times. Further, the durability of each planetary gear can be improved.

  The invention according to claim 2 is characterized in that a second bearing for rotatably supporting the ring gear is provided between the housing of the planetary gear mechanism and the outer peripheral surface of the extending portion of the ring gear. Yes.

  According to this invention, since the outer peripheral surface of the extension portion is supported by the second bearing, the planetary carrier can be supported more stably from the radial direction via the housing, and the ring gear can be supported via the extension portion. Since it is supported by the one bearing and the second bearing portion, a stable rotating action of the ring gear can be obtained. In particular, the radial support rigidity of the ring gear is increased.

  According to a third aspect of the present invention, the pressure which presses the ring gear in the first bearing direction between the inner end surface in the axial direction of the housing and the outer edge on the opposite side to the extending portion of the ring gear. It is characterized by providing a mechanism.

  According to this invention, since the ring gear is pressed in the first bearing direction (axial direction) by the pressing mechanism, the axial positioning is ensured.

  According to a fourth aspect of the present invention, the planetary gear mechanism includes a variable motor that rotationally drives a ring gear via a worm gear mechanism to vary a reduction ratio of the output shaft with respect to the steering shaft. It is a feature.

  According to the present invention, the worm gear of the worm gear mechanism integrally provided on the outer peripheral surface of the ring gear is supported by the housing by the first bearing and the second bearing via the ring gear extending portion. Stable support in direction is obtained.

  On the other hand, since the worm gear is pressed in the first bearing direction by the pressing mechanism, the gear gap (backlash gap) between the meshing teeth of the worm gear and the worm wheel is lost together with the radial stabilization support. It becomes possible. As a result, the rotational force transmitted from the variable motor to the worm gear mechanism can be efficiently transmitted to the ring gear.

  Hereinafter, an embodiment of a vehicle steering control device according to the present invention will be described in detail with reference to the drawings. This steering control device is also applied to a steer-by-wire system device as in the prior art.

  FIG. 2 schematically shows a steering control device for a vehicle according to the present embodiment. The steering shaft 2 is connected to the steering wheel 1, the rack and pinion mechanism 3 is an actuator for steering left and right front wheels FL and FR, and the steering. Steering means 4 for driving the rack and pinion mechanism 3 according to the steering angle of the shaft 2, provided independently of the steering means 4, and the rack and pinion mechanism 3 according to the steering angle of the steering shaft 2. And an electronic controller 6 which is a control means for mainly controlling the steering means 4 in accordance with the steering angle of the steering shaft 2.

  As shown in FIG. 2, the steering shaft 2 has a steering angle detected by a steering angle sensor 7, and a tip 2a is an input shaft of a later-described planetary gear mechanism 14 of the backup means 5. It is connected to.

  As shown in FIG. 1, the rack and pinion mechanism 3 includes a rack bar 10 that is linked to front wheels FL and FR on the left and right via tie rods 8 and 8 and knuckle arms 9 and 9, and a pinion that meshes with the rack bar 10. And a gear 11.

  The steering means 4 includes a gear mechanism 12 that applies a forward / reverse rotational force to the pinion gear 11 and a so-called reversible electric drive motor 13 that applies a forward / reverse rotational force to the gear mechanism 12. The drive motor 13 is controlled to rotate forward and backward based on a control signal from the electronic controller 6.

  As shown in FIG. 2, the backup means 5 includes a planetary gear mechanism 14 that is a variable gear mechanism linked to the steering shaft 2, and a lower shaft 15 that is connected to the output shaft 26 side of the planetary gear mechanism 14. And a torsion bar 16 disposed between the lower shaft 15 and the gear mechanism 12.

  Further, the rack and pinion mechanism 3 is provided with an actual steering angle sensor 17 that detects the actual turning angle of each of the steered wheels FL and FR according to the amount of movement of the rack bar 10.

  As shown in FIG. 1, the planetary gear mechanism 14 includes a first planetary gear unit housed in a housing 18 and a second planetary gear unit arranged in series with the first planetary gear unit. The first planetary gear unit meshes with an input shaft 19 connected to the steering shaft 2 from the axial direction, a first sun gear 20 provided integrally with the input shaft 19, and an outer peripheral tooth portion of the first sun gear 20. However, it comprises a plurality of (for example, three) first planetary gears 22 whose outer periphery revolves through the planetary carrier 21, and first ring gears 23 meshed with the outer peripheral teeth of each first planetary gear 22. ing.

  Further, the rotational force of the electric motor 24 which is an operating mechanism provided at the outer end portion of the housing 20 is transmitted to the first ring gear 23 via the worm gear mechanism 25.

  On the other hand, the second planetary gear unit has one end connected to the lower shaft 15 in the axial direction and the other end linked to the input shaft 19 so as to be relatively rotatable in the axial direction, and the output shaft 26. A second sun gear 27 fixed to the outer periphery of the other end of the shaft 26, and three second planetary gears 28 that revolve around the outer periphery via the planetary carrier 21 while meshing with the outer peripheral teeth of the second sun gear 27. And a second ring gear 29 meshed with the outer peripheral teeth of each of the second planetary gears 28. The second ring gear 29 is fixed to the housing 18 by bolts.

  The input shaft 19 is rotatably supported by a ball bearing 30 held by a hole edge of an insertion hole formed in the substantially center of the front cover 18 a of the housing 18, and the first sun gear 20 is provided at the tip thereof. Are serrated. The first sun gear 20 is in contact with the nut 31 screwed to the tip of the input shaft 19, the stopper ring 32 that is fitted to the outer periphery of the input shaft 19 and holds the ball bearing 30, and the axial ring. The support 33 is positioned in the axial direction.

  The output shaft 26 is rotatably supported by a ball bearing 34 held by a hole edge of an insertion hole formed in the center of the rear cover 18b of the housing 18, and a second sun gear 27 is provided at the tip of the output shaft 26. Serrated. The second sun gear 27 is positioned in the axial direction by a nut 35 screwed to substantially the center of the output shaft 26, a stopper ring 36 that holds the ball bearing 34, and a support portion 37.

  The planetary carrier 21 includes an annular carrier body 38 disposed between the first and second planetary gears 22 and 28, and the first planetary gear 22 and the second planetary body 22 sandwiching the carrier body 38. The planetary gears 23 are coaxially linked to each other, and three support shafts 39 that rotatably support the planetary gears 23 are arranged on the outer surface side of the planetary gears 22 and 23, and are drilled at equal intervals in the circumferential direction. Between the annular plate-like outer side support members 40 and 41 in which both end portions of the respective support shafts 39 are inserted through the provided insertion holes, and between the both side surfaces of the carrier body 38 and the opposed inner surfaces of the planetary gears 22 and 28. Ring-plate-like inner support members 42 and 43 respectively disposed on the support shafts 39. The planetary gears 22 and 23 are respectively connected by flange-shaped nuts 44 screwed to both ends of the respective support shafts 39 in the axial direction. each It is adapted to rotatably held between the support member 40 to 43.

  In the carrier body 38, shaft holes 38a through which the respective support shafts 39 are rotatably inserted are formed at equal circumferential positions in the circumferential direction so that the outer diameter thereof is larger than the outer diameter of each planetary gear 28 as a whole. While being set slightly smaller, an annular space C is formed between the inner peripheral surface and the nut 31.

  A plain bearing 45 that ensures smooth rotation of each planetary gear 22, 28 is interposed between each support shaft 39 and the insertion hole of each planetary gear 22, 28.

  The first ring gear 23 is integrally provided with a cylindrical extension 46 extending in the direction of the second ring gear 29 at the inner edge, and the inner peripheral surface and the outer periphery of the extension 46. A ball bearing type first bearing 47 and a second bearing 48 are provided on the surface.

  The extending portion 46 is formed in a stepped cylindrical shape having a diameter larger than the outer diameter of the first ring gear 23, and its length extends substantially to the vicinity of the inner edge of the rear cover 18b. An inner stepped portion 46a is formed on one end side of the first ring gear 23, while an outer stepped portion 46b is formed at a position substantially corresponding to the inner stepped portion 46a on the outer peripheral surface.

  In the first bearing 47, the inner ring 47a is press-fitted and fixed to the outer peripheral surface of the carrier body 38, and the outer ring 47b is press-fitted to the inner peripheral surface of the extension portion 46 and the end surface abuts on the inner stepped portion 46a. Directional positioning has been made. As a result, the carrier body 38 is rotatably supported by the extending portion 46 via the first bearing 47.

  In the second bearing 48, the inner ring 48a is press-fitted and fixed to the outer peripheral surface of the extending portion 46, the end surface is in contact with the outer stepped portion 46b, and the outer ring 48b is positioned in the inner periphery of the housing 18. It is press-fitted and fixed to the surface. As a result, the first ring gear 23 is rotatably supported by the second bearing 48 via the extending portion 46 and is positioned in the axial direction.

  The worm gear mechanism 25 includes a worm wheel 25a fixed to the drive shaft 24a of the electric motor 24, and a worm gear 25b fixed integrally with the outer peripheral surface of the first ring gear 23 and meshing with the worm wheel 25a. Has been.

  A pressing mechanism 49 that presses the first ring gear 23 and the worm gear 25b in the axial direction, that is, toward the first bearing 47 is provided on the outer peripheral portion of the inner peripheral surface of the front cover 18a.

  As shown in FIG. 1, the pressing mechanism 49 includes a wave-shaped spring member 50 held in an annular holding groove 18 c formed on the inner peripheral surface of the front cover 18 a, and an inner side of the spring member 50. An annular plate-shaped retainer 51 disposed, an annular pressing portion 52 that presses the other side surface of the first ring gear 23 and the other side surface of the worm gear 25 b, and an intervening space between the pressing portion 52 and the retainer 51. And a plurality of rollers 53 that ensure smooth rotation of the first ring gear 23 and the worm gear 25b against the pressing force of the spring member 50.

  The electric motor 24 rotates in the forward and reverse directions with a control current from the electronic controller 6, and the electric motor 24 rotates the first ring gear 23 and the first planetary gear 22 by this rotational force, and further passes through the planetary carrier 47. Thus, the second planetary gear 28 and the second sun gear 27 are rotated to change the rotation ratio (reduction ratio) between the input shaft 19 and the output shaft 26. The electric motor 24 is configured so that the current rotation angle ω is detected by the rotation angle sensor 54.

  The second planetary gear unit performs control to increase the rotation ratio decelerated by the first planetary gear unit by a predetermined amount. This speed increase ratio is the reduction ratio by the first planetary gear unit. Each is set arbitrarily in relation to the control.

  The electronic controller 6 has a built-in microcomputer, and as a basic control, as shown in FIG. 3, a current vehicle speed signal V output from a vehicle speed sensor (not shown) and a steering from the steering angle sensor 7 are used. The angle θ is input, and the actual turning angle target value δ1 and the steering reaction force target value T1 are calculated or determined by a preset map, and output from the target value determination circuit 60. The rack and pinion based on the actual turning angle target value δ1, the actual turning angle signal δ (feedback) from the actual steering angle sensor 17, the current rotation angle value ω of the electric motor 24 from the rotation angle sensor 54, and the like. A turning angle changing circuit 61 that changes the turning angles (steering positions) of the steered wheels FL and FR via the mechanism 3 is provided.

  Then, the rack and pinion mechanism 3 is operated via the gear mechanism 12 by outputting a feedback control signal to the drive motor 13 of the steering means 4 in accordance with the change signal output from the turning angle changing circuit 61 to drive the rotation. Thus, the steered angles of the steered wheels FL and FR are controlled.

  The electronic controller 6 also detects the steering reaction force target value signal T1 from the target value determination circuit 60, the steering angle signal θ from the steering angle sensor 7, and the current of the electric motor 24 output from the rotation angle sensor 54. From the rotation angle target determination circuit 62 that calculates the angular velocity value ω3 (the rotation angle target value of the electric motor 25) of the first ring gear 23 of the planetary gear mechanism 14 based on the rotation angle value ω, A motor that calculates the rotation angle θ2 of the output shaft 14b from the output angular velocity value ω3 and the current steering angle signal θ from the steering angle sensor 7 and outputs a feedback control signal to the electric motor 24. And a control circuit 63. The motor control circuit 63 controls the steering reaction force while causing the rotation angle θ2 of the output shaft 14b to follow the actual turning angle δ.

  Therefore, according to this embodiment, the steering reaction force when the steering wheel 1 is operated via the planetary gear mechanism 14 by controlling the rotation of the electric motor 24 by the rotation angle target determination circuit 62 and the motor control circuit 63, in particular. Can be optimally controlled.

  Further, since the planetary carrier 21 is supported by the first bearing 47 disposed on the inner peripheral surface of the extending portion 46 of the first ring gear 23, the support rigidity of the first and second planetary gears 22 and 28 is supported. In particular, since the first bearing 47 supports the center between the planetary gears 22 and 28 via the carrier body 38, stable support can be obtained.

  In addition, since the first bearing 47 supports the outer peripheral surface of the carrier body 38 in the holding state, the radial support rigidity is increased, and the planetary gears 22 and 28 can always rotate smoothly.

  Moreover, since the outer peripheral surface of the extension part 46 is supported by the second bearing 48, the planetary carrier 21 can be supported more stably from the radial direction.

  Further, since the first ring gear 23 is supported by the first bearing 47 and the second bearing portion 48 via the extending portion 46, a stable rotating action of the ring gear can be obtained. In particular, the radial support rigidity of the first ring gear 23 is increased.

  In this embodiment, the first ring gear 23 is pressed in the direction of the first bearing 46 (axial direction) by the spring member 50 of the pressing mechanism 49, so that the axial positioning is ensured and the first ring gear 23 is Since the worm gear 25b provided integrally with the one ring gear 23 is supported by the housing 18 by the first bearing 47 and the second bearing 48 via the extending portion 46, stable support in the radial direction is obtained.

  On the other hand, the worm gear 25b is pressed in the direction of the first bearing 47 by the spring member 50 via the retainer 51, the roller 53, and the pressing portion 52. Therefore, the worm gear 25b is coupled with the radial support. The gear gap (backlash gap) between the meshing teeth of the worm wheel 25a and the worm wheel 25a can be eliminated. As a result, the rotational force transmitted from the electric motor 24 to the worm gear mechanism 25 can be efficiently transmitted to the first ring gear 23.

  In this embodiment, when the drive motor 13 of the steering means 4 etc. breaks down and malfunctions, the steering shaft 2 rotates as the steering wheel 1 rotates, and the backup means 5 and the torsion bar By actuating the rack and pinion mechanism 3 via 16, it is possible to steer both steered wheels FL and FR. At this time, deceleration and speed increase ratio control by the planetary gear mechanism 14 is not performed, and steering assist can be performed by the electric motor 24.

The technical ideas other than the inventions described in the respective claims that can be grasped from the respective embodiments will be described below.
(1) The planetary gear mechanism includes a first planetary gear unit on the steering shaft side and a second planetary gear unit on the output shaft side, and each planetary gear unit is connected to the steering shaft and the output shaft, respectively. The first and second sun gears, the first and second ring gears arranged on the outer peripheral side of the sun gears, and the first and second ring gears are arranged between the ring gears and the sun gears to mesh with the gears. 1. A second planetary gear and a planetary carrier that links the planetary gears in the axial direction, and a central portion of the planetary carrier disposed between the planetary gears is rotatable by the first bearing. The vehicle steering control device according to claim 1, wherein the vehicle steering control device is supported.

  According to the present invention, since the central portion of the planetary carrier located between the planetary gears is supported by the first bearing, that is, the intermediate position between the planetary gears is supported by the first bearing. The gear can be supported in a balanced manner from the axial direction and the radial direction.

  The present invention is not limited to the configuration of each of the above-described embodiments. For example, the planetary gear mechanism can be formed as one planetary gear unit instead of two planetary gear units, and other planetary gear units can be formed. It is also possible to apply to a gear mechanism.

  In the present invention, the actual turning angle target value δ1 is calculated based on the steering angle θ from the steering angle sensor. However, a torque sensor is provided in the torsion bar 16, and the actual value is calculated based on the output value of the torque sensor. It is also possible to obtain the turning angle target value δ1.

It is a longitudinal cross-sectional view which shows the planetary gear mechanism with which the steering control apparatus of the vehicle in embodiment of this invention is provided. It is the schematic which shows the steering control apparatus of the vehicle provided to this embodiment. It is a control block diagram of the electronic controller in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Steering shaft 13 ... Drive motor 14 ... Planetary gear mechanism 19 ... Input shaft 20 ... 1st sun gear 21 ... Planetary carrier 22 ... 1st planetary gear 23 ... 1st ring gear 24 ... Electric motor 26 ... Output shaft 38 ... Carrier body 46 ... Extension part 47 ... 1st bearing 48 ... 2nd bearing 49 ... Pressing mechanism FL, FR ... Steering wheel

Claims (4)

A steering control device including a planetary gear mechanism that converts a rotational force transmitted from a steering shaft into a predetermined reduction ratio and transmits it to an output shaft,
The planetary gear mechanism is connected to the steering shaft, and a sun gear having outer teeth formed on the outer periphery;
A ring gear provided coaxially with the sun gear and having inner teeth formed on the inner periphery;
A planetary gear that meshes with the outer teeth of the sun gear and the inner teeth of the ring gear, and is supported so as to be revolved through a planetary carrier,
A cylindrical extension portion extending in the axial direction is formed at the inner edge of the ring gear, and the planetary carrier is rotatably supported by a bearing held on the inner peripheral surface of the extension portion. A vehicle steering control device. 2. The steering control according to claim 1, wherein a second bearing that rotatably supports the ring gear is provided between a housing of the planetary gear mechanism and an outer peripheral surface of the extending portion of the ring gear. apparatus. A pressing mechanism for pressing the ring gear in the first bearing direction is provided between an inner end surface in the axial direction of the housing and an outer edge on the opposite side to the extending portion of the ring gear. The vehicle steering control device according to claim 1 or 2. 4. The steering control device according to claim 3, wherein the planetary gear mechanism includes a variable motor that rotationally drives a ring gear via a worm gear mechanism to vary a reduction ratio of an output shaft with respect to the steering shaft. 5. .

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