JP3877387B2 - Variable steering angle ratio steering device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable steering angle ratio steering device for a vehicle that can automatically set a suitable steering angle ratio (ratio of a steering angle to a steering angle of a steering wheel) according to a driving operation situation of a vehicle by a driver. Is.
[0002]
[Prior art]
In Japanese Patent Laid-Open No. 4-283168, the target transmission ratio is calculated based on signals from the vehicle speed detection means and the road surface condition detection means, and the operation of the actuator is controlled to approximate the actual transmission ratio to the target transmission ratio. Thus, there has been proposed a vehicle steering apparatus in which an appropriate turning performance can always be obtained regardless of the vehicle speed and the road surface condition. The vehicle steering apparatus includes a transmission ratio variable mechanism capable of increasing / decreasing a ratio of a wheel turning angle to a wheel steering angle by operating an actuator, vehicle speed detecting means for detecting a vehicle speed, a tire, Road surface state detection means for detecting a friction coefficient with the road surface, transmission ratio calculation means for calculating a target transmission ratio based on signals from both detection means, and transmission ratio detection for detecting an actual transmission ratio of the transmission ratio variable mechanism Means for controlling the operation of the actuator so as to approximate the actual transmission ratio of the variable transmission ratio mechanism to the target transmission ratio by the control means.
[0003]
Japanese Patent Application Laid-Open No. 5-77751 discloses a correction steering angle required to predict a change in vehicle behavior due to a disturbance calculated from a lateral acceleration acting on the vehicle and a lateral component of inertial force and to cancel the change. A vehicle steering control device has been proposed that eliminates the need for correction steering for disturbances such as crosswinds when traveling straight ahead. This vehicle steering control device is configured as follows. In the disturbance lateral g controller that inputs the output signals of various sensors that detect the driving state of the vehicle while the vehicle is running, first, due to the disturbance from the tire turning angle, lateral acceleration, and the lateral component of the inertial force acting on the vehicle body. The horizontal g is calculated. In addition, the vehicle behavior change based on the lateral g due to the disturbance is predicted, the correction steering angle necessary to cancel the change is calculated, and the electric motor of the variable transmission rate control device is driven based on the calculation result. To eliminate changes in vehicle behavior due to external disturbances. Further, the correction amount of the steering assist force necessary for canceling the steering reaction force when the electric motor is driven is calculated, and the steering electric motor is driven based on the calculation result.
[0004]
[Problems to be solved by the invention]
Conventional vehicle steering devices can automatically set the steering angle ratio in response to the surrounding environment of the vehicle (disturbances such as road surface conditions and crosswinds), but the driver's intention (the driving of the vehicle by the driver) The steering angle ratio cannot be automatically set according to the situation. Although it is conceivable that the steering angle ratio can be set manually, an operation for changing the steering angle ratio is required every time the driving state of the vehicle changes, which is troublesome. It is convenient if the steering angle ratio is automatically set according to the driver's intention (the driving situation of the vehicle by the driver). For example, the steering angle ratio is set to a large value when driving lightly on mountain roads with continuous curves, and the steering angle ratio is set appropriately when driving on an expressway at almost constant speed (cruising). If it is, it is convenient.
[0005]
The present invention has been made to solve such a problem, and it is possible to automatically set a suitable steering angle ratio (ratio of the steering angle to the steering angle of the steering wheel) according to the driving operation status of the vehicle by the driver. Thus, an object of the present invention is to provide a variable steering angle ratio steering device for a vehicle that can obtain an optimum steering feeling in accordance with the will of the driver.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, a variable steering angle ratio steering device for a vehicle according to the present invention includes: A variable steering angle ratio of a vehicle in which a variable steering angle ratio device capable of changing the amount of rotation of the steered wheels relative to the steering wheel is provided in a steering system from the steering wheel to the steering wheel, and a control device for controlling the variable steering angle ratio device is provided. In the steering device, An operation situation determining means for determining the operation situation of the vehicle by the driver is provided, and the control device Has multiple control modes, Based on the signal from the operation status determination means Increase or decrease the threshold for switching the control mode It is characterized by doing.
[0007]
The operation state determining means may detect the steering operation frequency by the driver, and the control device may set the steering angle ratio to be larger as the steering operation frequency is higher.
[0008]
The operation status determination means may detect the accelerator operation frequency and the brake operation frequency by the driver, and the control device may set the steering angle ratio to be larger as the accelerator operation frequency and the brake operation frequency are higher.
[0009]
further, The operation status determination means detects the shift change frequency of the driver, and the control device receives a signal from the operation status determination means, and the greater the shift change frequency, the greater the steering angle ratio of the variable steering angle ratio device. You may make it do.
[0010]
The variable steering angle ratio steering device for a vehicle according to the present invention can automatically set the steering angle ratio based on the driving operation status of the vehicle by the driver. For example, a large rudder angle ratio is set when driving lightly on mountain roads with continuous curves, and a small rudder angle ratio is set when traveling on a highway at almost constant speed (cruising). A medium steering angle ratio can be set during normal driving other than.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic structural diagram showing the overall configuration of a variable steering angle ratio steering apparatus for a vehicle according to the present invention. A variable steering angle ratio steering device for a vehicle according to the present invention includes a variable steering angle ratio device 10 provided in a steering system from a steering wheel (steering wheel) 1 to a steering wheel 9, an operating angle of a steering wheel, an operating speed, an accelerator pedal. The operation status determining means 50 for determining the operation status based on the vehicle operation information by the driver, such as the operation of the brake pedal, and the variable steering angle ratio device 10 based on the signal from the operation status determining means 50 are controlled. And a control device 60.
[0012]
A steering shaft 2 provided integrally with the handle 1 is connected to an input shaft of the variable steering angle ratio device 10 via a connecting shaft 4 having universal joints 3 and 3. The variable steering angle ratio device 10 uses a device that can continuously vary the ratio (β / α) of the rotation angle (β) of the output shaft to the rotation angle (α) of the input shaft. By rotating the pinion 5 provided on the output shaft of the variable rudder angle ratio device 10 with the rack teeth of the rack shaft 6, the rotational motion of the output shaft is converted into the linear motion (L) of the rack shaft 6. Is converted into a turning motion (T) of the steered wheels 9 through the tie rod 7 and the knuckle arm 8.
[0013]
2 to 4 show a specific example of the variable rudder angle ratio device, FIG. 2 is a sectional view of the variable rudder angle ratio device, FIG. 3 is an exploded perspective view of a shaft portion of the variable rudder angle ratio device, and FIG. These are sectional drawings which follow the AA line of FIG.
[0014]
As shown in FIG. 2, the input shaft 11 is rotatably supported via a ball bearing 15 at an eccentric position of a support member 14 that is rotatably supported by the upper casing 13 a via a ball bearing 12. . A coupling 16 that transmits a rotational force to the output shaft 17 is formed at an end of the input shaft 11 that has entered the lower casing 13 b.
[0015]
The output shaft 17 integrally formed with the pinion 5 meshed with the rack 6 is rotatably supported by the lower casing 13b via a pair of ball bearings 18a and 18b. At the end of the output shaft 17 that has entered the lower casing 13 b, an intermediate shaft 19 projects from the center of the output shaft 17. The intermediate shaft 19 and the coupling 16 integrally formed with the input shaft 11 are connected to each other via a slider 21 and a tapered roller bearing 22 with a flat needle bearing 20 interposed therebetween. Further, a seal member S having a flexible cylindrical portion is provided between the input shaft 11 and the upper casing 13a so that the airtightness in the variable steering angle ratio device 10 is maintained. It has become.
[0016]
As shown in FIG. 3, a groove 23 having a trapezoidal cross section is formed in the lower surface of the coupling 16. The slider 21 with the pair of flat needle bearings 20 interposed therebetween is engaged in the groove 23 so as to slide on the inclined surfaces of the groove 23 facing each other. Further, an intermediate shaft 19 is engaged with the center portion of the lower surface of the slider 21 so as to be relatively rotatable via a tapered roller bearing 22.
[0017]
As shown in FIG. 2, an adjustment screw 24 that abuts against an outer race of a ball bearing 18b that supports the lower end of the output shaft 17 is screwed into the lower casing 13b. By appropriately tightening the adjustment screw 24, the pinion 5 is pressed in the axial direction, and an appropriate preload is applied between the input shaft 11 and the output shaft 17 via the coupling 16. As a result, the coupling 16 can be improved by removing the backlash of the coupling 16.
[0018]
As shown in FIG. 4, a fan-shaped partial worm wheel 25 is formed on a part of the outer peripheral portion of the support member 14. The partial worm wheel 25 is meshed with a worm 28 driven by a motor 27 via a worm speed reduction mechanism 26 and can give a rotational motion to the support member 14 over a predetermined angular range. It can be done. The worm 28 is supported by the upper casing 13a via a backlash removing member 29 applying an eccentric cam, and a hexagonal bar wrench is engaged with a hexagon hole 30 provided at an end of the backlash removing member 29. By rotating this with respect to the upper casing 13a, the shaft core moves and the meshing with the partial worm wheel 25 changes. In addition, the worm 28 and the worm speed reduction mechanism 26 are connected via an Oldham coupling 31 in order to allow movement of the axis of the worm 28.
[0019]
A displacement sensor 33 made up of a differential transformer or the like is attached to the upper casing 13a in order to engage with a pin 32 projecting from the upper surface of the support member 14 and detect the rotation angle of the support member 14. . Thereby, the rotation amount of the support member 14, that is, the eccentric amount signal (actual eccentric amount) 33a of the input shaft 11 supported by the displacement sensor 33 is output.
[0020]
The drive unit 65 in the control device 60 includes a target eccentric amount corresponding to the steering angle ratio (target steering angle ratio) set based on the driving operation state of the vehicle and the vehicle speed, and the actual eccentric amount detected by the displacement sensor 33 ( The motor 27 is operated by feedback control so as to match the actual steering angle ratio (33a).
[0021]
FIG. 5 is an explanatory diagram showing the operating principle of the variable steering angle ratio device, FIG. 6 is a graph showing the steering angle ratio characteristics of the variable steering angle ratio device, and FIG. 7 is a steering angle ratio realized using the variable steering angle ratio device. It is a steering angle ratio characteristic diagram which shows an example of a characteristic.
[0022]
As shown in FIG. 5, the rotation center of the input shaft 11 is A, the rotation center of the output shaft 17 is B, the action point of the intermediate shaft 19 is C, the dimension between BC is b, and the input shaft 11 and the output shaft 17 When the displacement amount (dimension between AB) is a, the rotation angle (handle steering angle) of the input shaft 11 is α, and the rotation angle (pinion rotation angle) of the output shaft 17 is β,
b · sin β = (b · cos β−a) tan α
Because
α = tan ^-1 (B · sin β / (b · cos β-a))
It is represented by
[0023]
When the input shaft 11 is rotated, the intermediate shaft 19 is rotated around the axis of the output shaft 17 by the engagement with the slider 21 of the coupling 16 of the input shaft 11. Here, when the support member 14 is rotated, the shaft center of the input shaft 11 changes within the range indicated by reference signs A <b> 0 to A <b> 2 in FIGS. 3 and 4 due to the eccentric cam action of the support member 14. As a result, when the amount of deviation a between the input and output shafts is appropriately determined and the shaft centers of the input shaft 11 and the output shaft 17 are decentered from each other, the rotation angles of the input shaft 11 and the output shaft 17 become inconsistent. . Moreover, the change in the angle of the output shaft 17 when the input shaft 11 is rotated by equal angles gradually increases (see the thick line (a1) and the thin line (a2) in FIG. 6).
[0024]
Here, the rotational angle of the input shaft 11 is changed by continuously changing the amount of deviation a of the axis between the input shaft 11 and the output shaft 17 within a range of a2 to a0 (a2>a1> a0 = 0). The ratio (β / α) of the rotation angle of the output shaft 17 with respect to the angle, that is, the practical steering angle ratio can be continuously changed, and when the deviation a between the input and output shafts is increased, the output with respect to the input angle α If the rate of change of the angle β is gradually improved and the deviation amount a between the input and output axes is set to 0, the input angle α and the output angle β become equal, as indicated by a one-dot chain line (a0) in FIG.
[0025]
If the change in the steering angle ratio is controlled to be, for example, the a0 side in the low-speed traveling region and the a2 side in the high-speed traveling region, it becomes possible to change the steering angle ratio characteristic in the range indicated by the bold line in FIG. In the low-speed driving area, the rack stroke L with respect to the steering angle α of the steering wheel (steering wheel) can be set larger than that of the conventional steering device to realize more sensitive characteristics. The rack stroke L with respect to the steering angle α of the steering wheel can be made smaller than that of a conventional steering device, and more insensitive (stable) characteristics can be realized. Therefore, a practical relationship between the steering angle of the steering wheel (steering wheel) and the traveling speed can be made flat. In addition to changing the rudder angle ratio according to the vehicle speed, a more suitable rudder angle ratio is set according to the driver's operation state of the vehicle, so that the steering according to the driver's operation state of the vehicle is possible. The characteristic / steering feeling can be obtained.
[0026]
FIG. 8 is an overall block diagram of the variable steering angle ratio steering apparatus according to the present invention. The variable steering angle ratio steering device includes an operation state determination unit 50, mode designation information 50a supplied from the operation state determination unit 50, and a signal (hereinafter referred to as a vehicle speed) 75a related to the vehicle speed supplied from the vehicle speed detector 75. And a control device 60 that controls the rudder angle ratio of the variable rudder angle device 10. Reference BAT is a battery power source.
[0027]
The operation status determining means 50 includes a signal related to the steering wheel operation angle detected by the steering wheel operation angle detector 71 (hereinafter referred to as a steering wheel operation angle) 71a, and a signal related to the accelerator pedal position detected by the accelerator pedal position detector 72 (hereinafter referred to as the steering wheel operation angle). 72a, a signal related to the brake pedal position detected by the brake pedal position detector 73 (hereinafter referred to as a brake pedal position) 73a, a signal related to the shift lever position detected by the shift lever position detector 74. (Hereinafter referred to as shift lever position) The vehicle operation status by the driver based on a signal related to the driving operation of the vehicle such as 74a is as follows: Mode 1 (Quick mode), Mode 2 (Normal mode), Mode 3 (Slow mode) ) And the mode designation information 50a for designating the decided mode is output. To.
[0028]
The control device 60 includes three types of steering angle ratio setting units 61, 62, and 63 having different control modes (vehicle speed-steering angle ratio characteristics), and a control mode switching unit 64 that switches a control mode to be used based on the mode designation information 50a. And a drive unit 65 that drives the variable steering angle ratio device 10 based on a signal (hereinafter referred to as a target steering angle ratio) 64a relating to the target steering angle ratio supplied via the control mode switching unit 64.
[0029]
Each steering angle ratio setting unit 61, 62, 63 includes a vehicle speed corresponding steering angle ratio setting table for setting the steering angle ratio with respect to the vehicle speed, and outputs a steering angle ratio registered in advance corresponding to the vehicle speed 75a. . The steering angle ratio setting unit 61 for mode 1 (quick) is a large steering angle ratio, the steering angle ratio setting unit 62 for mode 2 (normal) is a moderate steering angle ratio, and the steering for mode 3 (slow mode). The angle ratio setting unit 63 is configured to set a small steering angle ratio. In addition, the value (maximum steering angle ratio) of the steering angle ratio at the extremely low vehicle speed is set to the same value in each steering angle ratio setting table. The steering angle ratio value (minimum steering angle ratio) at an extremely high vehicle speed is set to the same value in each steering angle ratio setting table. By changing the change characteristics of the steering angle ratio in the intermediate vehicle speed range, mode 1 (quick mode) with a relatively high steering angle ratio, mode 2 (normal mode) with a moderate steering angle ratio, and steering Three control modes, mode 3 (slow mode) with a relatively small angular ratio, are provided.
[0030]
FIG. 9 is a functional block configuration diagram showing a specific example of the operation status determining means. The operation status determination means 50 includes a mode determination counter unit 51, a steering speed calculation unit 52, an accelerator frequency calculation unit 53, a brake frequency calculation unit 54, a shift change frequency calculation unit 55, a mode determination unit 56, A mode determination reference value correction unit 57.
[0031]
The mode determination counter unit 51 determines the size of the handle operation angle (the operation angle from the neutral position to the right or left) in a plurality of stages based on the handle operation angle 71a. The counter value N of the determination counter is increased, and when the steering angle is small, the counter value N of the mode determination counter is decreased. The counter value N of the mode determination counter is supplied to the mode determination unit 56.
[0032]
The steering speed calculation unit 52 captures the steering wheel operation angle 71a at a predetermined time interval, temporarily stores the captured steering wheel operation angle 71a over a predetermined period, and determines the steering speed (the steering wheel operation) from the amount of change in the steering wheel operation angle 71a. Speed) dθ is obtained. The steering speed dθ is supplied to the mode determination reference value correction unit 57.
[0033]
The accelerator frequency calculation unit 53 captures the accelerator pedal position 72a at a predetermined time interval, temporarily stores the captured accelerator pedal position 72a for a predetermined period, and calculates an accelerator frequency (accelerator operation frequency) A in the predetermined period. Ask. The accelerator frequency A is supplied to the mode determination reference value correction unit 57.
[0034]
The brake frequency calculation unit 54 captures the brake pedal position 73a at a predetermined time interval, temporarily stores the captured brake pedal position 73a over a predetermined period, and calculates a brake frequency (brake operation frequency) B in the predetermined period. Ask. The brake frequency B is supplied to the mode determination reference value correction unit 57.
[0035]
The shift change frequency calculation unit 55 captures the shift lever position 74a at a predetermined time interval, temporarily stores the captured shift lever position 74a for a predetermined period, and shift shift frequency (shift change operation frequency in a predetermined period). ) Find S. The shift change frequency S is supplied to the mode determination reference value correction unit 57.
[0036]
The mode determination unit 56 compares the counter value N of the mode determination counter with the mode 1 determination value TH1 and the mode 3 determination value TH3 supplied from the mode determination reference value correction unit 57, and compares the mode 1 to mode 3 Either mode is determined and the mode designation information 50a is output. Specifically, when the counter value N is larger than the mode 1 determination value TH1, it is determined as mode 1 (quick), and when the counter value N is smaller than the mode 3 determination value TH3, it is determined as mode 3 (slow). Otherwise, it is determined as mode 2 (normal).
[0037]
The mode determination reference value correction unit 57 sets the mode 1 determination value TH1 and the mode 3 determination value based on the steering speed dθ, the accelerator frequency A, the brake frequency B, and the shift change frequency S. The mode determination reference value correction unit 57 selects mode 1 (quick) when the steering speed dθ is fast, when the accelerator frequency A is high, when the brake frequency B is high, and when the shift change frequency S is high. The mode 1 determination value TH1 is decreased so as to be easy, and the mode 3 determination value is decreased so that the mode 3 (slow) is not easily selected. On the other hand, the mode determination reference value correction unit 57 performs mode 1 (quick) when the steering speed dθ is slow, when the accelerator frequency A is low, when the brake frequency B is low, and when the shift change frequency S is low. The mode 1 determination value TH1 is increased so that it is difficult to select the mode 3, and the mode 3 determination value is increased so that the mode 3 (slow) is easily selected.
[0038]
FIG. 10 is a flowchart showing the overall operation of the operation status determining means shown in FIG. When an ignition switch (not shown) or the like of the vehicle is operated and power is supplied to the variable steering angle ratio steering device, the counter value N is set to 100 and the mode 1 determination value TH1 is set to 200 in the initialization process shown in step S1. The mode 3 determination value TH3 is initialized to 0, respectively. After the initialization process is completed, the processes after step S2 are repeated at predetermined time intervals (for example, 0.5 seconds or 1 second).
[0039]
Steps S <b> 2 to S <b> 5 show the operation of the mode determination counter unit 51. In step S2, the mode determination counter unit 51 determines the size of the handle operating angle 71a. When the handle operating angle 71a (the absolute value of the handle operating angle) is small (for example, less than 20 degrees), the mode determination counter unit 51 decreases the counter value N by a small amount (for example, 0.05) (step S3). When the steering wheel operation angle 71a is medium (for example, 20 degrees to 30 or 40 degrees), the mode determination counter unit 51 increases the counter value N by a first predetermined amount (for example, 1) (step S4). When the steering wheel operation angle 71a is large (for example, 30 or 40 degrees or more), the mode determination counter unit 51 increases the counter value N by a second predetermined amount (for example, 2) larger than the first predetermined amount (step S5). ).
[0040]
In step S6, the mode determination reference value correction unit 55 corrects the mode determination reference values TH1 and TH3. The mode determination reference value correction process will be described later with reference to FIG.
[0041]
Steps S7 to S11 show the operation of the mode determination unit 56. When the counter value N is smaller than the mode 3 (slow mode) determination value TH3 (step S9), the mode determination unit 56 selects mode 3 (slow mode) and outputs mode specification information 50a for specifying mode 3 (Step S9). When the counter value N is larger than the mode 3 (slow mode) determination value TH3, the mode determination unit 56 determines the magnitude relationship between the counter value N and the mode 1 (quick mode) determination value TH1 in step S8. When the counter value N is smaller than the mode 1 (quick mode) determination value TH1, the mode determination unit 56 selects mode 2 (normal mode) and outputs mode specifying information 50a for specifying mode 2 (step S10). When the counter value N is larger than the mode 1 (quick mode) determination value TH1, the mode determination unit 56 selects mode 1 and outputs mode specification information 50a for specifying mode 1 (step S11).
[0042]
FIG. 11 is a flowchart showing the operation of the mode determination reference value correction unit. The mode determination reference value correction unit 57 determines whether or not the steering operation speed is fast by comparing the magnitude relationship between the steering speed dθ and the preset steering speed threshold THdθ (step S21). When the steering speed dθ is larger than the steering speed threshold THdθ, that is, when a fast steering operation is performed, the mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (for example, 1 And a mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S22). The mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (when the steering speed dθ is smaller than the steering speed threshold THdθ, that is, when a slow steering operation is performed). For example, 1) is increased, and the mode 3 (slow mode) determination value TH3 is increased by a predetermined value (for example, 1) (step S23).
[0043]
Next, the mode determination reference value correction unit 57 determines whether or not the accelerator operation is frequently performed by comparing the magnitude relationship between the accelerator frequency A and a preset accelerator frequency threshold value THA (step S1). S24). The mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (for example, 1) when the accelerator frequency A is greater than the accelerator frequency threshold THA, that is, when the accelerator operation frequency is high. At the same time, the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S25). The mode determination reference value correcting unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (for example, 1) when the accelerator frequency A is smaller than the accelerator frequency threshold THA, that is, when the frequency of the accelerator operation is low. At the same time, the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (eg, 1) (step S26).
[0044]
Next, the mode determination reference value correction unit 57 determines whether or not the brake operation is frequently performed by comparing the magnitude relationship between the brake frequency B and a preset brake frequency threshold value THB (step S1). S27). The mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (for example, 1) when the brake frequency B is greater than the brake frequency threshold value THB, that is, when the frequency of brake operation is high. At the same time, the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S28). The mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value (for example, 1) when the brake frequency B is smaller than the brake frequency threshold value THB, that is, when the frequency of brake operation is low. At the same time, the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S29).
[0045]
Next, the mode determination reference value correction unit 57 determines whether the shift change operation is frequently performed by comparing the magnitude relationship between the shift change frequency S and a preset shift change frequency threshold value THS. (Step S30). When the shift change frequency S is larger than the shift change frequency threshold value THS, that is, when the frequency of the shift change operation is high, the mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value ( For example, 1) decrease, and the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S31). When the shift change frequency S is smaller than the shift change frequency threshold THS, that is, when the frequency of the shift change operation is low, the mode determination reference value correction unit 57 sets the mode 1 (quick mode) determination value TH1 to a predetermined value ( For example, 1) increase, and the mode 3 (slow mode) determination value TH3 is decreased by a predetermined value (for example, 1) (step S32).
[0046]
Since the counter value is initialized to 100, the mode 1 (quick mode) determination value TH1 is set to 200, and the mode 3 (slow mode determination value) is initially set to 0 by the initialization process shown in step S1 of FIG. The operation status determining means 50 outputs mode designation information 50a for designating mode 2 (normal mode) in the initial state. Then, the operation status determination means 50 determines the size of the steering wheel operating angle at predetermined time intervals, and if the steering wheel is operated in a large manner, the operating value determining unit 50 increases the counter value N greatly (for example, +2), thereby increasing the intermediate operating angle. When the steering wheel is operated, the counter value N is increased finely (for example, +1), and when the steering wheel operating angle is small, the counter value N is decreased by a small amount (for example, 0.05) to thereby decrease the steering wheel operating angle. The counter value N corresponding to the size of the handle and the operation frequency of the handle is obtained, and the mode value is compared with the mode determination values TH1 and TH3 to shift to the mode 1 (quick mode) and the mode 3 (slow mode). Like to do.
[0047]
Further, the operation status determining means 50 changes the mode determination values TH1 and TH3 based on the steering speed dθ, the accelerator frequency A, the brake frequency B, and the shift change frequency S, thereby enabling mode 1 (quick mode) and mode 3 Transition to (slow mode) can be made promptly. That is, when an early steering operation is performed, an accelerator or brake operation is frequently performed, and a shift change is frequently performed, the mode 1 (quick mode) determination value TH1 is decreased. This makes it easy to shift to mode 1 (quick mode). In addition, when the steering wheel is operated slowly and the frequency of accelerator, brake, and shift change is low, the mode 3 (slow mode) judgment value TH3 is increased to easily shift to mode 3 (slow mode). is doing.
[0048]
In the present embodiment, the count value N of the mode determination counter is increased or decreased according to the handle operating angle, and the mode determination values TH1 and TH3 are set based on the handle operating speed and the frequency of accelerator, brake, and shift change. Although the operation situation determination means 50 configured to determine the operation situation (driving situation) of the vehicle by the driver while being variable is illustrated, the operation situation determination means 50 uses the fuzzy reasoning to determine the operation situation of the vehicle by the driver ( It is good also as a structure which judges a driving | operation condition.
[0049]
FIG. 12 is a block diagram showing a specific example of the drive unit. The drive unit 65 includes a bridge connection of a target eccentricity determination unit 81, a deviation calculation unit 82, a PID control unit 83, a PWM signal generation unit 84, a gate drive circuit unit 85, and four power field effect transistors. Motor driving circuit 86.
[0050]
The target eccentricity determination unit 81 includes a conversion table for converting the target steering angle ratio 64a into the target eccentricity amount 81a. The target steering angle ratio 64a is supplied to the target steering angle ratio 64a supplied via the control mode switching unit 64. The target eccentric amount 81a of the variable rudder angle device 10 for obtaining 64a is output. The deviation calculating unit 82 obtains a deviation between the target eccentric amount 81a and the actual eccentric amount (corresponding to the actual steering angle ratio) 33a detected by the displacement sensor 33, and outputs a deviation signal 82a. The PID control unit 83 performs processing such as proportionality, integration, and differentiation on the deviation signal 82a, and generates a drive control signal 83a indicating the direction and current value of the current supplied to the motor 27 in order to make the deviation close to zero. And output. The PWM signal generation unit 84 generates and outputs a PWM (pulse width modulation) signal 84a for performing PWM operation of the motor 27 based on the drive control signal 83a. The gate drive circuit unit 85 drives the gates of the field effect transistors of the motor drive circuit 86 based on the PWM signal 84a to drive the field effect transistors.
[0051]
With the above-described configuration, the variable steering angle ratio steering apparatus for a vehicle according to the present invention is the driving operation status of the vehicle by the driver (the operating angle of the steering wheel, the operating speed of the steering wheel, the operating frequency of the accelerator, the brake, the shift change). Based on the above, for example, whether you are driving lightly on mountain roads, driving city streets normally, driving cruising (driving at almost constant speed), etc. Since the determination unit 50 determines and the control mode of the steering angle ratio is selected according to the determined operation situation, the steering angle ratio suitable for the driving situation according to the driver's will can be automatically set. . For example, when driving lightly on mountain roads, etc., the steering angle ratio can be set relatively high to enable light driving operation, and when driving on expressways, etc. By setting it relatively small, it is possible to perform a stable operation.
[0052]
In the present embodiment, the configuration in which the accelerator operation is detected based on the accelerator pedal position is shown, but the accelerator operation may be detected based on the opening of the throttle valve. Moreover, although the structure which detects brake operation based on a brake pedal position was shown, you may make it detect brake operation based on lighting information of brake oil pressure or a brake lamp. Furthermore, instead of detecting the steering wheel operation angle, accelerator operation, and brake operation, the vehicle is driven based on changes in the vehicle speed (deceleration, acceleration), vehicle speed change frequency, vehicle lateral acceleration, etc., and their change frequency. The driving situation by the person may be determined.
[0053]
【The invention's effect】
As described above, the variable steering angle ratio steering device for a vehicle according to the present invention includes an operation situation determination unit that determines an operation situation based on a driving operation situation of a vehicle by a driver, and an operation situation that is determined by the operation situation determination unit. And a control device that controls the rudder angle of the variable rudder angle ratio device, and the rudder angle ratio can be automatically controlled according to the driving operation situation of the vehicle according to the driver's will.
[0054]
For example, a large rudder angle ratio is set when driving lightly on mountain roads with continuous curves, and a small rudder angle ratio is set when traveling on a highway at almost constant speed (cruising). Since the steering angle ratio at a medium level can be set during normal driving other than the above, an optimum steering feeling can be realized according to the driving state of the driver.
[Brief description of the drawings]
FIG. 1 is a schematic structural diagram showing the overall configuration of a variable steering angle ratio steering apparatus according to the present invention.
FIG. 2 is a sectional view of a variable steering angle ratio device.
FIG. 3 is an exploded perspective view of a shaft portion of a variable rudder angle ratio device.
4 is a sectional view taken along line AA in FIG.
FIG. 5 is an explanatory diagram showing the operating principle of the variable rudder angle ratio device.
FIG. 6 is a graph showing the steering angle ratio characteristics of the variable steering angle ratio device.
FIG. 7 is a steering angle ratio characteristic diagram showing an example of a steering angle ratio characteristic realized using a variable steering angle ratio device.
FIG. 8 is an overall block diagram of a variable steering angle ratio steering device according to the present invention.
FIG. 9 is a functional block configuration diagram showing a specific example of operation status determination means;
FIG. 10 is a flowchart showing the overall operation of the operation status determining means shown in FIG.
FIG. 11 is a flowchart showing the operation of the mode determination reference value correction unit.
FIG. 12 is a block diagram showing a specific example of a drive unit in the control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Steering wheel (steering wheel), 10 ... Variable steering angle ratio apparatus, 27 ... Motor, 33 ... Displacement sensor, 50 ... Operation condition determination means, 51 ... Mode determination counter part, 52 ... Steering speed calculating part, 53 ... Accelerator Frequency calculation unit, 54 ... brake frequency calculation unit, 55 ... shift change frequency calculation unit, 56 ... mode determination unit, 57 ... mode determination reference value correction unit, 60 ... control device, 61 ... steer angle for mode 1 (quick mode) Ratio setting unit 62 ... Steering angle ratio setting unit for mode 2 (normal mode), 63 ... Steering angle ratio setting unit for mode 3 (slow mode), 64 ... Control mode switching unit, 65 ... Drive unit, 71 ... Steering operation Angle detector, 72 ... accelerator pedal position detector, 73 ... brake pedal position detector, 74 ... shift lever position detector, 75 ... vehicle speed detector.

Claims (4)

A variable steering angle ratio of a vehicle in which a variable steering angle ratio device capable of changing the amount of rotation of the steered wheels relative to the steering wheel is provided in a steering system from the steering wheel to the steering wheel, and a control device for controlling the variable steering angle ratio device is provided. In the steering device,
An operation status determining means for determining the operation status of the vehicle by the driver is provided, and the control device has a plurality of control modes, and increases or decreases a threshold at which the control mode is switched based on a signal from the operation status determination means. A variable steering angle ratio steering apparatus for vehicles.   The operation status determination means detects the steering operation frequency of the driver, and the control device receives a signal from the operation status determination means, and increases the steering angle ratio of the variable steering angle ratio device as the steering wheel operation frequency increases. The variable steering angle ratio steering device for a vehicle according to claim 1, wherein the steering angle ratio steering device is increased.   The operation situation determination means detects the operation frequency of the driver's accelerator pedal and brake pedal, and the control device receives a signal from the operation situation determination means, and the greater the operation frequency of the accelerator pedal and brake pedal, 2. The variable steering angle ratio steering device for a vehicle according to claim 1, wherein the steering angle ratio of the variable steering angle ratio device is increased. The operation status determination means detects a driver's shift change frequency, and the control device receives a signal from the operation status determination means, and the greater the shift change frequency is, the more the steering angle ratio of the variable steering angle ratio device is determined. The variable steering angle ratio steering apparatus for a vehicle according to claim 1, wherein the steering angle ratio steering apparatus is increased .

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