JP2005035359A - Steering control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use an inexpensive steering angle sensor for detecting a steering angle by making a detecting object of the steering angle sensor as a member reduced in speed to below one rotation. <P>SOLUTION: This steering control device is provided with a first planetary gear mechanism 14 of a planetary gear mechanism linked with a steering shaft 2 of a steering wheel 1 for controlling an output shaft 4 to a prescribed rotational speed reduction ratio, and a second planetary gear mechanism 15 for transmitting the rotation by a speed increase ratio substantially opposite to the speed reduction ratio of the first planetary gear mechanism 14. The speed reduction ratio by the first planetary gear mechanism 14 is set to be below one rotation in relation to maximum numbers of rotation of left and right steering shafts. A steering angle detecting sensor 31 detects a rotational angle of below one rotation of a planetary carrier 19 of the first planetary gear mechanism 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering control device for a vehicle, and for example, relates to a steering control device for a steer-by-wire type vehicle in which a steering wheel and a front wheel steering drive mechanism are separated.
[0002]
[Prior art]
As a conventional vehicle steering control device, for example, the one described in Patent Document 1 below is known. In this vehicle steering control device, the steering shaft to the left and right steered wheels are connected to the steering shaft. It is in a state of being directly connected via a rack and pinion gear.
[0003]
For this reason, it has been impossible to give a turning angle different from the rotation of the steering wheel by giving a rotational phase difference between the steering wheel and the turning wheel. That is, for example, when entering the garage, the turning amount of the steered wheels is increased with respect to the turning operation of the steering wheel, or when turning the vehicle, the turning angle of the steered wheels is set regardless of the turning operation of the steering wheel. Control such as avoiding danger by controlling is not possible.
[0004]
Therefore, in order to give a degree of freedom to the output of the output shaft on the steered wheel side with respect to the input shaft on the steering wheel side, a conventional technique described in Patent Document 2 below is also provided.
[0005]
This is because a planetary gear mechanism is interposed between the input shaft and the output shaft, and the phase difference between the input shaft and the output shaft is adjusted by controlling the reduction ratio of the input shaft by the planetary gear mechanism. It has become.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-79951 (FIG. 1)
[0007]
[Patent Document 2]
Japanese Examined Patent Publication No. 54-34212 [0008]
[Problems to be solved by the invention]
In the latter vehicle steering control device, in order to adjust and control the phase difference, it is necessary to detect the number of rotations of the steering wheel as a control parameter. A steering angle sensor for detecting the number of rotations, which is a corner, is expensive because it requires structurally complicated and highly accurate parts. Therefore, the cost of the apparatus is inevitably increased.
[0009]
[Means for Solving the Problems]
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 reduction ratio by the reduction mechanism is set to the rotational speed of the input shaft. On the other hand, the steering angle detection means is configured to detect an angle of 1 rotation or less that is decelerated by the speed reduction mechanism.
[0010]
According to the present invention, the steering angle detection target is not directly detecting the rotational speed of the input shaft, but is an angle of one rotation or less, that is, an angle of 360 ° or less, which is reduced by the speed reduction mechanism. In addition to being able to detect the number of rotations of the wheel, it is possible to use a steering angle sensor having a simple structure and inexpensive parts. As a result, the cost of the apparatus can be reduced.
[0011]
The invention according to claim 2 is characterized in that when the electric motor of the phase difference adjusting mechanism stops due to a failure, a speed increasing mechanism is provided that changes to a speed increasing ratio almost opposite to the speed reducing ratio by the speed reducing mechanism. Yes.
[0012]
According to the present invention, when the steering wheel is rotated when the phase difference adjusting mechanism fails, the rotation angle of the input shaft is decelerated at the predetermined reduction ratio by the reduction mechanism, and then the reduction ratio is directly changed by the speed increase mechanism. Therefore, the steered wheels are steered at a steered angle substantially the same as the steering angle of the steering wheel. Therefore, it is possible to sufficiently suppress the occurrence of the steering discomfort for the vehicle driver.
[0013]
In other words, if the steering rotation angle of the steering wheel is transmitted to the steered wheels while being decelerated by the speed reduction mechanism, the steered amount of the steered wheels becomes very large relative to the amount of rotation of the steering wheel, and the driver is steered. However, the present invention can eliminate this problem.
[0014]
According to a third aspect of the present invention, the speed reduction mechanism and the speed increase mechanism are each formed by a planetary gear.
[0015]
According to the present invention, since both mechanisms are constituted by planetary gears, both mechanisms can be organically linked, and gear reduction of the reduction ratio and the speed increase ratio can be performed together.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a vehicle steering control device according to the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 shows an outline of a steering control device for a vehicle according to a first embodiment. A steering shaft 2 (input shaft) connected to a steering wheel 1 and a rack and pinion for steering front left and right steered wheels FL and FR. A steering mechanism 5 for driving the rack and pinion mechanism 3 via an output shaft 4 in accordance with the steering angle of the steering shaft 2; and the steering shaft 2 provided independently of the steering means 5. Back-up means 6 for driving the rack and pinion mechanism 3 according to the steering angle, and an electronic controller 7 for mainly controlling the steering means 5 according to the steering angle of the steering shaft 2.
[0018]
As shown in FIG. 1, the steering shaft 2 is linked with a tip end portion 2 a being rotatably supported by a ball bearing 23 on a housing 17 of a planetary gear mechanism (to be described later) of the backup means 6.
[0019]
The rack and pinion mechanism 3 includes a rack bar 8 fixed to a tie rod 10 and a pinion gear 9 that meshes with the rack bar 8, and the rack bar 8 is a knuckle connected to both ends of the tie rod 10. It is linked to both steered wheels FL, FR via arms 10a, 10a.
[0020]
As shown in FIG. 1, the output shaft 4 is connected to the steering shaft 2 via a planetary gear, and is connected to the upper shaft 4a via an intermediate shaft 4b or a universal joint. The lower pin 4c is connected to the pinion gear 9 of the rack and pinion mechanism 3. The upper shaft 4 a is rotatably supported by a ball bearing 30 fixed to the inner peripheral surface of the other end opening of the housing 17.
[0021]
The steering means 5 includes a reduction gear mechanism 11 linked to the pinion gear 9 via the lower shaft 4c, and an electric drive motor 12 that rotationally drives the pinion gear 9 via the gear mechanism 11. The gear mechanism 11 has an actual turning angle which is an actual turning angle detection means for detecting the sliding position of the rack bar 8 and detecting the actual turning angle of the current both turning wheels FL and FR. A sensor 13 is provided.
[0022]
The backup means 6 is constituted by a planetary gear, and a first planetary gear mechanism 14 that is a reduction mechanism that drives the rack and pinion mechanism 3 in synchronization with the steering angle of the steering shaft 2, and the first planetary gear. A second planetary gear mechanism 15, which is a speed increasing mechanism that is arranged in series with the gear mechanism 14 and increases the rotational speed of the steering shaft 2 decelerated by the first planetary gear mechanism 14 and transmits it to the output shaft 4; The second planetary gear mechanism 15 includes a phase difference adjusting mechanism 16 that controls the rotation of the second planetary gear mechanism 15 to adjust the rotational phase difference between the steering shaft 2 and the output shaft 4.
[0023]
As shown in FIGS. 1 and 3, the planetary gear mechanisms 14 and 15 are arranged in series in the front and rear in one housing 17, and the first planetary gear mechanism 14 is arranged from substantially the center of the housing 17. A first sun gear 18 integrally coupled to the steering shaft 2 inserted inside, and the outer periphery of the first sun gear 18 revolving through a plurality of support shafts 19 a of the planetary carrier 19 while meshing with the outer peripheral teeth of the first sun gear 18. A plurality of (for example, four) first planetary gears 20 and a first ring gear 21 meshed with an outer peripheral tooth portion of the first planetary gear 20.
[0024]
The first ring gear 21 is fixed to the inner end of the housing 17 by a bolt 22 in a non-rotating state.
[0025]
The first planetary gear mechanism 147 generally rotates the planetary carrier 19 with respect to the rotation speed of the steering wheel 1 that is about 3.5 to 4 rotations when left and right, that is, the maximum rotation speed of the steering shaft 2. The speed is reduced so that the number becomes one rotation or less.
[0026]
On the other hand, the second planetary gear mechanism 15 meshes with the second sun gear 24 integrally coupled to the upper shaft 4 a of the output shaft 4 at the center and the outer peripheral tooth portion of the second sun gear 24. Of the second planetary gear 25 that revolves around the outer periphery thereof, and a second ring gear 26 that has inner teeth meshing with the outer peripheral teeth of the second planetary gear 25 on the inner peripheral portion. The second planetary gear 25 is coaxially provided on the same support shaft 19 a of the first planetary gear 20 and the planetary carrier 19.
[0027]
The second planetary gear mechanism 15 rotates the output shaft 4 with a speed increasing ratio almost opposite to the speed reduction ratio of the first planetary gear mechanism 14. For example, the second planetary gear mechanism 15 once with respect to one rotation of the steering shaft 2. The rotation reduced by the first planetary gear mechanism 14 is increased in the second planetary gear mechanism 15 so that the output shaft 4 is also substantially rotated once.
[0028]
As shown in FIGS. 1 and 3, the phase difference adjusting mechanism 16 includes a second ring gear 26 of the second planetary gear mechanism 15 and an outer end portion of the housing 17 in the axial direction of the second planetary gear mechanism 15. A reversible electric motor 27 provided in a direction perpendicular to the electric motor 27 and a worm gear mechanism that is a transmission gear mechanism provided between the electric motor 27 and the second ring gear 26 are configured.
[0029]
The worm gear mechanism includes a worm shaft 28 coupled to the rotating shaft 27a of the electric motor 27, and a worm wheel 29 formed on the outer peripheral surface of the second ring gear 26 and meshing with the worm shaft 28. The rotational force transmitted from the electric motor 27 is transmitted to the second ring gear 26, and the speed increase ratio is made variable via the second planetary gear 25 and the second sun gear 24 by the rotation of the second ring gear 26. It has become.
[0030]
As shown in FIG. 3, the worm shaft 28 is rotatably supported by ball bearings 35 and 36 whose both end portions are fixed inside the housing 17, and the first planetary gear mechanism 14 is provided. Between the planetary carrier 19 and the housing 17, there is provided an optical sensor type steering angle sensor 31 which is a steering angle detection means for detecting the steering angle and steering torque of the steering wheel 1.
[0031]
That is, as shown in FIGS. 1 and 2, the steering angle sensor 31 includes a ring-shaped detected member 32 fixed to the outer peripheral side outer surface of the first planetary carrier 19 with a bolt or an adhesive, and a lower end of the housing 17. The light detector 33 is inserted into and fixed to the inside from the opening and detects the rotation angle of the member 32 to be detected.
[0032]
The detection member 32 has a flange-like test portion 32a at the tip of the annular base fixed to the first planetary carrier 19, and a plurality of light beams are arranged at equal intervals in the circumferential direction of the test portion 32a. A transmission slit 32b is formed. Further, a neutral position detection hole 32c is formed at one position in the circumferential direction on the front surface of the test portion 32a, and the rotation angle is detected with the neutral position detection hole 32c as a reference point. Yes.
[0033]
The photodetector 33 is formed in a substantially U-shaped cross-section such that the inner peripheral end 33a sandwiches the test portion 32a with a predetermined gap, and light is emitted during this time to transmit the light through the slit 32b. In addition, a rotation angle detecting element is accommodated therein.
[0034]
As shown in FIG. 1, the electronic controller 7 has a built-in microcomputer, and inputs the steering angles θ1 and θ2 from the steering angle sensor 31 and the actual steering angle sensor 13 to input the drive motor 12 and the electric motor. 27 is configured to output a control current. Further, a failure detection circuit (not shown) for detecting a failure of the drive motor 12 of the steering means 5 is provided, and when a failure detection signal is input from the failure detection circuit, the energization to the drive motor 12 is cut off. It is supposed to be.
[0035]
Hereinafter, specific control of the drive motor 12 and the electric motor 27 by the electronic controller 8 will be described based on the flowchart of FIG.
[0036]
First, in step 1, the steering angle of the steering shaft 2 is read from the steering angle sensor 31, and the actual turning angle is read from the sliding position of the rack bar 8 from the actual turning angle sensor 13.
[0037]
Subsequently, in step 2, a failure detection signal is read from the failure detection circuit. Next, in step 3, it is determined whether or not a failure detection signal from the failure detection circuit is input. That is, a fail safe is determined as to whether or not the drive motor 12 or the like has failed and is locked.
[0038]
If YES, that is, if it is determined that the vehicle is normally driven, the process proceeds to step 4 where a table is based on the steering angle information input from the steering angle sensor 31 and the actual turning angle sensor 13. A target steering angle is generated by a map or calculation.
[0039]
Next, the process proceeds to step 5 where a steering reaction force target torque is generated. That is, the driver cannot obtain a good steering feeling unless there is a certain amount of steering reaction force when the steering wheel 1 is rotated. In the present embodiment, the steering wheel FL, The steering reaction force transmitted from the FR is transmitted from the planetary gear mechanism to the steering shaft 2 via the gear mechanism 11. Therefore, the steering reaction force target torque is determined in step 5 based on the target steering angle.
[0040]
Subsequently, in step 6, a control current is output to the drive motor 12 in order to operate the rack and pinion mechanism 3 in accordance with the target steering angle generated in step 4.
[0041]
Next, in step 7, the difference value between the calculated actual steering angle value and the target steering angle value is calculated, and the process returns to step 6, and driving is performed so that an appropriate steering angle is obtained from the difference value. A control current is output to the motor 12. As a result, a left or right rotational force is applied to the rack and pinion mechanism 3 to perform normal steering control on the steered wheels FL and FR.
[0042]
In addition, after the steering reaction force target torque is generated in step 5, the process proceeds to step 8 at the same time, where the electric motor 27 is used to cancel the phase difference generated between the steering shaft 2 and the output shaft 21. Output the control current. Thus, an appropriate speed increasing ratio is generated by the second planetary gear mechanism 15.
[0043]
Thereafter, the process proceeds to step 9, where the steering angle input from the steering angle sensor 31, the actual turning angle input from the actual turning angle sensor 13, and the generated target torque value are taken into consideration again. Returning to step 8, a control current is output to the electric motor 27 in order to always obtain a reaction torque that matches the target torque.
[0044]
On the other hand, if it is determined as NO in step 3, that is, if the drive motor 12 of the steering means 5 fails and a lock or the like occurs, the process proceeds to step 10.
[0045]
Here, energization of the drive motor 12 is interrupted, and the drive of the steering means 5 is stopped.
[0046]
Subsequently, in step 11, the energization of the electric motor 27 is cut off, and the variable control of the speed increasing ratio between the steering shaft 2 and the output shaft 4 is stopped.
[0047]
Accordingly, when the driver rotates the steering wheel 1, the rotational torque of the steering shaft 2 is transmitted from the first sun gear 18 to the first planetary gear 20, and further transmitted to the second planetary gear 25 via the planetary carrier 19. From here, it is transmitted to the second sun gear 24 and the output shaft 4. As a result, the rack and pinion mechanism 3 is manually operated, and the steering wheels FL and FR can be manually steered, that is, backed up.
[0048]
At the time of this failure, since the electric current to the electric motor 27 is cut off, the rotation ratio between the steering shaft 2 and the output shaft 4 is determined by the reduction ratio and the acceleration ratio by the first and second planetary gear mechanisms 14 and 15. The fixed ratio is approximately 1: 1.
[0049]
As described above, according to the present embodiment, when the steering means 5 breaks down for some reason and is locked, for example, the planetary gear mechanism uses the rack and pinion mechanism to manually rotate the steering wheel 1. No matter what equipment of the steering means 5 breaks down, the backup means 6 is not affected in any way, and the planetary gear mechanism is independently driven regardless of the steering means 5 to By operating the pinion mechanism 3, it becomes possible to perform fail-safe control of the steered wheels FL and FR in a so-called manual steering state.
[0050]
Therefore, the steering wheel FL, FR can be reliably controlled without any trouble by the normal rotation operation of the steering wheel 1, and the safety is improved.
[0051]
Further, when the steering means 5 is normally driven, as described above, the electric motor 27 is rotationally driven and a steering reaction force is applied to the steering shaft 2 by the planetary gear mechanism. The steering feeling becomes better.
[0052]
In this embodiment, the target of detection of the steering angle by the steering angle sensor 31 is not the number of rotations of the steering shaft 2 (steering wheel 1), but an angle of one rotation or less reduced by the first planetary gear mechanism 14, that is, The angle of 360 ° or less, that is, the steering angle sensor 31 only needs to detect the rotation angle of one or less rotations of the decelerated planetary carrier 19, so that the number of rotations of the steering shaft 2 can be detected. This makes it possible to use the steering angle sensor 31 that is simple and inexpensive. As a result, the cost of the apparatus can be reduced.
[0053]
Further, when the electric motor 27 of the phase difference adjusting mechanism 16 breaks down, as described above, the rotation angle of the steering shaft 2 is decelerated and increased by the planetary gear mechanism, and both the steered wheels FL and FR are turned into the steering wheel. Steering control is performed at a steering angle that is substantially the same ratio as the steering angle of 1.
[0054]
Therefore, it is possible to sufficiently suppress the occurrence of the steering discomfort for the vehicle driver.
[0055]
Further, since the speed reduction and speed increasing mechanisms are constituted by the first and second planetary gear mechanisms 14 and 15, both mechanisms 14 and 15 can be organically linked. Gear variable can be performed together.
[0056]
Further, since the electric motor 27 and the second ring gear 26 are linked by the worm gear mechanism, as described above, when the electric motor 27 fails, the speed is reduced from the first planetary gear mechanism 14 to the second planetary gear mechanism 15. When the rotating force is transmitted, the free rotation of the second ring gear 26 is prevented by the worm gear mechanism, so that the rotating force of the first planetary gear mechanism 14 is efficiently transmitted to the second planetary gear mechanism 15. It becomes possible to make it.
[0057]
FIG. 5 shows a second embodiment of the present invention, in which the structure of the steering angle sensor is changed.
[0058]
That is, the steering angle sensor 41 is a magnetic sensitive type, and a magnetic ring 42 is fixed to the outer peripheral portion of the planetary carrier 19 with a bolt or the like, and a tip end portion of the magnetic ring 42 on the outer peripheral side end portion of the housing 17. A magnetic detector 43 directed to 42 is fixed.
[0059]
The magnetic ring 42 is formed in an annular shape, and N poles and S poles are alternately arranged along the circumferential direction on the front surface, and a non-magnetic pole for detecting a neutral position on one inner peripheral side thereof. A portion 42a is formed.
[0060]
The magnetic detector 43 has a detection surface for detecting a rotation angle inside the detection surface of the tip end portion 43a facing each of the poles. The data is output to the electronic controller 7.
[0061]
Therefore, according to this embodiment, the same operational effects as those of the first embodiment can be obtained, and the steering angle sensor 41 is of a magnetic sensitive type, so that the cost can be further reduced.
[0062]
The technical ideas other than the claims that can be grasped from the embodiments will be described below.
(1) The phase adjustment mechanism includes a ring gear of one of the speed increasing mechanism and the speed reducing mechanism, an electric motor that controls the rotation of the ring gear via a transmission gear mechanism, and the electric motor. 4. The vehicle steering control device according to claim 3, wherein the vehicle steering control device comprises a controller for controlling the vehicle.
(2) The vehicle steering control device according to (1), wherein the transmission gear mechanism is constituted by a worm gear mechanism.
[0063]
According to the present invention, when the electric motor of the phase adjustment mechanism fails, when the reduced rotational force is transmitted from the first planetary gear mechanism to the second planetary gear mechanism, the ring gear is freed by the worm gear mechanism. Therefore, the rotational force of the first planetary gear mechanism can be efficiently transmitted to the second planetary gear mechanism.
[0064]
The present invention is not limited to the configuration of each of the above-described embodiments. For example, the reduction mechanism and the speed increasing mechanism are replaced with a planetary gear mechanism, and disclosed, for example, in a satellite gear mechanism or Japanese Patent Application Laid-Open No. 2002-255046. It is also possible to use a ball screw mechanism as described above.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vehicle steering control device showing a cross-sectional view of a planetary gear mechanism used in a first embodiment of the present invention.
FIG. 2 is a front view showing a part of the detected member of the steering angle sensor provided in the embodiment in a cutaway manner.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a control flowchart of the electronic controller in the present embodiment.
FIG. 5 is a cross-sectional view of a planetary gear mechanism provided for the second embodiment.
FIG. 6 is a front view showing a part of the magnetic ring of the steering angle sensor provided in the embodiment in a cutaway state.
[Explanation of symbols]
1 ... steering wheel 2 ... steering shaft (input shaft)
DESCRIPTION OF SYMBOLS 3 ... Rack and pinion mechanism 4 ... Output shaft 5 ... Steering means 6 ... Backup means 7 ... Electronic controller 12 ... Drive motor 13 ... Actual turning angle sensor (actual turning angle detection means)
DESCRIPTION OF SYMBOLS 14 ... 1st planetary gear mechanism 15 ... 2nd planetary gear mechanism 16 ... Phase adjustment mechanism 26 ... 2nd ring gear 28 ... Worm shaft 29 ... Worm wheel FL * FR ... Steering wheel

Claims (3)

An input shaft coupled to the steering wheel;
Steering angle detection means for detecting the steering angle of the input shaft;
An output shaft linked to the steered wheel and linked to the input shaft;
A turning angle detection means provided on the output shaft for detecting a turning angle of the steered wheels;
Steering means for applying a steering force to the steered wheels via the output shaft based on respective angle information signals from the steering angle detecting means and the steered angle detecting means;
A reduction mechanism that is provided between the input shaft and the output shaft and converts rotation transmitted from the input shaft to the output shaft into a predetermined reduction ratio;
In a vehicle steering control device including a phase difference adjustment mechanism that adjusts a phase difference when a rotational phase difference occurs between the input shaft and the output shaft,
The speed reduction mechanism sets the speed reduction ratio to be 1 rotation or less with respect to the maximum rotational speed of the left and right of the input shaft,
The steering control device for a vehicle, wherein the steering angle detecting means detects an angle of one rotation or less decelerated by the deceleration mechanism. 2. The vehicle according to claim 1, further comprising a speed increasing mechanism that changes to a speed increasing ratio substantially opposite to a speed reducing ratio by the speed reducing mechanism when the electric motor of the phase difference adjusting mechanism stops due to a failure. Steering control device. The vehicle steering control device according to claim 2, wherein each of the speed reduction mechanism and the speed increase mechanism is formed by planetary gears.

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