JP4240205B2 - Steering system transmission ratio variable system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering system transmission ratio variable system that changes a turning angle of a steered wheel with respect to a steering angle of a steering wheel according to a driving situation.
[0002]
[Prior art]
This type of steering system transmission ratio variable system is generally called “VGRS” (Variable Gear Ratio System), and an actuator is connected to the steering system of an automobile, depending on the steering angle of the steering wheel, the vehicle speed, and other driving information. By controlling the driving of the actuator, the turning angle of the steered wheel with respect to the steering angle of the steering wheel is changed according to the driving situation. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Patent No. 3232032 ([0002] [0003])
[0004]
[Problems to be solved by the invention]
By the way, since the steering angle of the steering wheel when the vehicle is traveling straight becomes a singular point (so-called 0 point), it is necessary to perform control by determining whether or not the vehicle is traveling straight.
[0005]
Therefore, in VGRS under development, the steering angle of the steering wheel is detected by a steering angle sensor, and whether or not the vehicle is in a straight traveling state is determined depending on whether or not the detection angle of the steering angle sensor is near 0 point. It was detected.
[0006]
However, even when the steering angle of the steering wheel is 0 point, there may be a case where the vehicle is not traveling straight due to a delay in following the actuator. For this reason, in the VGRS under development, although it is not when the vehicle is traveling straight, there may have been a situation in which it is erroneously detected that the vehicle is traveling straight and control for traveling straight is performed.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering system transmission ratio variable system capable of accurately detecting whether or not the vehicle is in a straight traveling state.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a steering system transmission ratio variable system according to the invention of claim 1 connects a handle provided in a vehicle to a body of an actuator, while a steering wheel swing mechanism is connected to an output rotating portion of the actuator. And a steering angle sensor that detects the steering angle of the steering wheel in a transmission ratio variable system that drives and controls the actuator so that the correspondence between the steering angle of the steering wheel and the turning angle of the steering wheel is changed according to the driving situation. An act angle sensor that detects the rotation angle of the output rotation unit, a steering angle zero point data that is output from the steering angle sensor when the steering angle of the steering wheel is zero for the vehicle to go straight, and a rotation output Storage means for storing the act angle 0 point data output from the act angle sensor when the rotation angle of the unit becomes 0 point for causing the vehicle to go straight, and the detection result of the rudder angle sensor indicates the steering angle 0 Straight traveling state detection means for data and one match and a detection result of an act angle sensor in the condition that the duration of the state that match the act angle 0 point data exceeds a reference time vehicle detects that it is running straight And features.
[0009]
According to a second aspect of the present invention, in the steering system transmission ratio variable system according to the first aspect, when the straight traveling state is detected by the straight traveling state detecting means, the output rotating portion of the actuator is held unrotatable with respect to the body. It is characterized by a mechanical lock.
[0011]
[Action and effect of the invention]
<Invention of Claim 1>
In the steering system transmission ratio variable system according to the first aspect, since it is determined that the vehicle is in the straight traveling state only when both the steering wheel and the output rotating portion of the actuator are at 0 point, This makes it possible to eliminate the erroneous detection due to the following delay, and to detect the straight traveling state of the vehicle more accurately than in the past.
[0012]
<Invention of Claim 2>
In the steering system transmission ratio variable system according to the second aspect, since the output rotating portion of the actuator is locked to the body by the mechanical lock when the vehicle is traveling straight, the rigidity of the steering system when the steering wheel is at 0 point is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment according to the invention will be described with reference to FIGS. FIG. 1 shows an overall configuration of a steering system transmission ratio variable system 11 according to the present invention. In the figure, reference numeral 14 denotes an actuator, which includes a differential reduction gear 22 and a servo motor 23 that drives the reduction gear 22.
[0015]
As shown in FIG. 2, the speed reducer 22 includes a cylindrical body 52 having a bottom having one end, a cylindrical output rotating portion 51 having a bottom having a one end accommodated inside the body 52, and an output rotation thereof. And an input rotating part 54 accommodated inside the part 51. Differential teeth 51 </ b> A and 52 </ b> A having different numbers of teeth are formed on the inner peripheral surface of the body 52 and the outer peripheral surface of the output rotating portion 51. The input rotating portion 54 is formed by fitting a bearing on the outer side of the eccentric disk, and one end of the rotor 60 in the servo motor 23 is fixed to the eccentric disk. The input rotating unit 54 presses a part of the inner peripheral surface of the output rotating unit 51, and the pressing portion changes as the rotor 60 rotates.
[0016]
A peripheral wall that covers the periphery of the input rotation unit 54 in the output rotation unit 51 is flexible and can be locally pressed against the inner peripheral surface of the body 52. Accordingly, the meshing portion of the differential teeth 51A and 52A between the output rotating portion 51 and the body 52 changes with the rotation of the input rotating portion 54, and each time the input rotating portion 54 makes one rotation, the differential teeth 51A, The output rotation unit 51 rotates by the difference in the number of teeth of 52A.
[0017]
A stator 61 of the servo motor 23 is integrated with the body 52 of the speed reducer 22. A base end portion of the servo motor 23 opposite to the speed reducer 22 is shown in FIG. 3, and a mechanical lock 75 is provided here. The mechanical lock 75 includes a lock ring 62 fitted to the base end portion of the rotor 60, a lock arm 70 provided on the base end surface of the stator 61 so as to be swingable, and a solenoid element 63 for driving the lock arm 70. . The lock arm 70 is pivotally supported by a shaft body 64 erected from the base end surface of the stator 61 at an intermediate portion in the longitudinal direction. A linear motion rod 63 </ b> R provided in the solenoid element 63 is connected to the base end portion of the lock arm 70, and a lock protrusion 71 projects toward the lock ring 62 at the distal end portion of the lock arm 70. When the solenoid element 63 is energized, the lock arm 70 is rotated so as to press the lock protrusion 71 against the lock ring 62. On the other hand, when the solenoid element 63 is de-energized, the lock arm is held by a spring body built in the solenoid element 63. 70 reverses and disengages from the lock ring 62.
[0018]
A deep groove 66 is formed in the lock ring 62 at a position where the outer peripheral surface is equally arranged. Then, the lock projection 71 of the lock arm 70 is concavo-convexly fitted into the deep groove portion 66 so that the rotor 60 is locked together with the lock ring 62 so as not to rotate.
[0019]
As shown in FIG. 2, a casing 77 is fixed to the stator 61 of the servo motor 23, and an input side steering shaft 15 is fixed to the opposite side of the casing 77 to the speed reducer 22. A handle 12 (see FIG. 1) is fixed to the steering shaft 15. As a result, the stator 61 of the servo motor 23 and the body 52 of the speed reducer 22 rotate together with the handle 12.
[0020]
The output side steering shaft 16 is fixed to the output rotating portion 51 of the speed reducer 22. The output side steering shaft 16 is arranged coaxially with the input side steering shaft 15, and a pinion gear 17 is connected to one end of the output side steering shaft 16 as shown in FIG. 1. The pinion gear 17 meshes with a rack 18 extending between the steering wheels 20, 20, and tie rods 19, 19 extend from both ends of the rack 18, and these tie rods 19, 19 are connected to the left and right steering wheels 20, 20. It is connected to the rotation support portion 21 to constitute the “steering wheel swing mechanism” according to the present invention. Thereby, the turning angle of the left and right steering wheels 20 and 20 is changed in conjunction with the rotation of the output side steering shaft 16.
[0021]
A steering angle sensor 30 is provided in the middle of the input side steering shaft 15, and the steering angle θ 1 of the handle 12 can be detected by the steering angle sensor 30. Further, an act angle sensor 31 is provided in the middle of the output side steering shaft 16, and the act angle sensor 31 can detect the rotation angle of the output rotating portion 51 (hereinafter referred to as “act angle θ2”). .
[0022]
The servo motor 23 described above is driven and controlled by the ECU 10. The CPU 25 provided in the ECU 10 takes in the output signal of the position sensor 23E provided in the servo motor 23. Further, the CPU 25 incorporates driving information such as the vehicle speed V detected by the vehicle speed sensor 32, the steering angle θ1 detected by the steering angle sensor 30, and the act angle θ2 detected by the act angle sensor 31. The servomotor 23 is driven and controlled so that the turning angle of the steered wheels 20 with respect to the steering angle θ1 of the handle 12 changes according to the driving situation.
[0023]
Incidentally, the steering angle θ1 of the steering wheel 12 and the act angle θ2 of the actuator 14 in a straight traveling state of the vehicle are generally called “0 points”. In the EEPROM 26 (storage means) provided in the ECU 10, the steering angle 0 point data θ10 output by the steering angle sensor 30 when the steering angle θ1 is 0 point, and the act angle sensor when the act angle θ2 is 0 point. The act angle 0-point data θ11 output by 31 is stored.
[0024]
Then, the CPU 25 determines whether or not the vehicle is in the straight traveling state by executing the straight traveling state detection program P1 shown in FIG. The straight traveling state detection program P1 will be described together with the following operation description.
[0025]
Next, the operation of the steering system transmission ratio variable system 11 of the present embodiment having the above configuration will be described. In the steering system transmission ratio variable system 11 of the present embodiment, the actuator 14 (specifically, the servo motor 23) is driven and controlled in accordance with driving information such as the steering angle θ1 and the vehicle speed V. Thereby, the turning angle of the steered wheels 20 and 20 with respect to the steering angle θ1 is changed. Specifically, for example, when traveling at a low speed, the turning angle of the steered wheels 20 with respect to the steering angle θ1 becomes relatively large, and parking or the like becomes easy. On the other hand, when the vehicle is traveling at a high speed, the turning angle of the steered wheel 20 with respect to the steering angle θ1 is relatively small, and sudden steering at a high speed can be prevented.
[0026]
Now, during driving | running | working of a motor vehicle, CPU25 of ECU10 runs the straight traveling state detection program P1 shown in FIG. 4 with a predetermined period. When the straight traveling state detection program P1 is run, it is checked whether the difference Δθ1 between the steering angle θ1 detected by the steering angle sensor 30 and the steering angle zero point data θ10 stored in the EEPROM 26 is equal to or smaller than a predetermined reference value K1. (S1). Here, if the difference Δθ1 is equal to or smaller than the reference value K1 (YES in S1), it is determined that the steering angle θ1 coincides with the 0 point, and then the act angle θ2 detected by the act angle sensor 31 is detected. It is checked whether the difference Δθ2 with respect to the act angle 0 point data θ11 stored in the EEPROM 26 is equal to or smaller than a predetermined reference value K2 (S2). Here, when the difference Δθ2 is equal to or smaller than the reference value K2 (YES in S2), it is determined that the act angle θ2 matches the 0 point.
[0027]
Next, the duration of the state where the steering angle θ1 and the act angle θ2 are both coincident with the zero point is measured by a predetermined timer, and it is checked whether or not the measurement time exceeds the reference time (S3). Specifically, when the steering angle θ1 and the act angle θ2 both coincide with the zero point, if the timer is not measuring, the measurement is started and the straight-running state detection program P1 is exited. When the straight traveling state detection program P1 is repeated at a predetermined cycle, the state in which the steering angle θ1 and the act angle θ2 both coincide with the zero point continues, and the measured time of the timer exceeds the reference time (S3). YES), it is determined that the vehicle is traveling straight (S4), and the lock process (S5) is executed.
In the present embodiment, the above-described steps S1, S2 and S3 constitute the “straight-running state detecting means” according to the present invention.
[0028]
When the lock process (S5) is executed, the solenoid element 63 is turned on and the lock arm 70 is pressed against the lock ring 62 side. As a result, the lock protrusion 71 of the lock arm 70 is engaged with the deep groove 66 of the lock ring 62 so that the rotor 60 is locked to the body 52 so as not to rotate. Then, as long as the state where the steering angle θ1 and the act angle θ2 are both coincident with the zero point continues, this locked state is maintained.
[0029]
Further, when either the steering angle θ1 or the act angle θ2 does not coincide with the 0 point while the straight traveling state detection program P1 is repeated at a predetermined cycle (NO in S1 or S2), the vehicle is not in the straight traveling state. (S6), and the lock process is released (S7). That is, the solenoid element 63 is turned off, and the lock arm 70 is detached from the lock ring 62 by the spring body built in the solenoid element 63. As a result, the rotor 60 is returned to a rotatable state with respect to the body 52, and normal control is performed.
[0030]
As described above, in the steering system transmission ratio variable system 11 according to the present embodiment, when the steering wheel 12 and the output rotation portion 51 of the actuator 14 and the rotation position detected by the steering angle sensor 30 and the act angle sensor 31 are both at the zero point. However, since it is determined that the vehicle is traveling straight, erroneous detection due to the follow-up delay of the actuator is eliminated as in the prior art, and the straight traveling state of the vehicle can be detected more accurately than in the past. When the vehicle is in a straight traveling state, the output rotation unit 51 of the actuator 14 is locked to the body 52 by the mechanical lock 75, so that the rigidity of the steering system near the zero point of the handle 12 is improved.
[0031]
<Other embodiments>
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.
(1) In the steering system transmission ratio variable system 11 of the above embodiment, the output rotation unit 51 of the actuator 14 is locked to the body 52 by the mechanical lock 75, but the output rotation unit 51 of the actuator 14 is electrically locked to the body. It may be configured to perform (so-called servo lock).
[0032]
(2) In the above-described embodiment, the output rotation portion of the actuator is locked when the straight traveling state of the vehicle is detected. However, in the case where the output rotation portion of the actuator is not locked during straight travel, the output rotation of the handle and the actuator The straight traveling state of the vehicle may be detected when both parts are at 0 points.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a steering transmission ratio variable system according to an embodiment of the present invention. FIG. 2 is a partially broken perspective view of an actuator. FIG. 3 is a perspective view of a lock mechanism. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Steering system transmission ratio variable system 12 ... Handle 14 ... Actuator 20 ... Steering wheel 30 ... Steering angle sensor 31 ... Act angle sensor 51 ... Output rotation part 52 ... Body 75 ... Mechanical lock P1 ... Straight running state detection program

Claims (2)

A steering wheel provided on the vehicle is connected to the body of the actuator, and a steering wheel swing mechanism is connected to the output rotating portion of the actuator so that the steering angle of the steering wheel and the turning angle of the steering wheel correspond to the driving situation. In a steering system transmission ratio variable system that drives and controls the actuator to change according to
A steering angle sensor for detecting the steering angle of the steering wheel;
An act angle sensor for detecting a rotation angle of the output rotation unit;
Steering angle 0 point data output from the steering angle sensor when the steering angle of the steering wheel becomes 0 point for causing the vehicle to go straight, and the rotation angle of the rotation output unit for causing the vehicle to go straight Storage means for storing act angle 0 point data output from the act angle sensor when 0 point is reached;
The steering angle detection result of the sensor is on condition that the one and the steering angle 0 point data match and duration of a state where the detection result of the act angle sensor is match with the act angle 0 point data exceeds the reference time A steering system transmission ratio variable system comprising: a straight traveling state detecting means for detecting that the vehicle is traveling straight. 2. The steering system according to claim 1, further comprising a mechanical lock that holds the output rotating portion of the actuator so as not to rotate with respect to the body when the straight traveling state is detected by the straight traveling state detecting means. Variable transmission ratio system.

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