JP4028653B2 - Variable steering angle ratio steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable steering angle ratio steering apparatus that can change a steering angle ratio of a steering system, and more particularly to a variable steering angle ratio steering apparatus that can arbitrarily select a steering angle ratio by a switch operation of a driver.
[0002]
[Prior art]
The conventional variable rudder angle ratio steering device is a variable that can change the rudder angle ratio, which is the ratio of the steered wheel steered angle to the steering wheel steered angle, as disclosed in Japanese Patent Application Laid-Open No. 7-257406. A steering angle ratio mechanism is provided to drive the electric motor based on the vehicle speed signal detected by the vehicle speed sensor, to uniquely determine the steering angle ratio according to the vehicle speed signal by driving the motor, and to increase the steering angle ratio at low vehicle speeds. The steering of the vehicle is made quick, and the steering angle ratio is reduced at high vehicle speeds to stabilize the behavior of the vehicle.
[0003]
Thus, by determining the rudder angle ratio according to the vehicle speed, it is possible to secure handling at a parking lot, sharp handling at low and medium vehicle speeds, and stability of the vehicle at high vehicle speeds.
[0004]
[Problems to be solved by the invention]
In the variable steering angle ratio steering apparatus disclosed in Japanese Patent Laid-Open No. 7-257406, the target steering angle ratio is uniquely determined with respect to the vehicle speed, so that the place and situation where the vehicle travels, for example, the road width is wide. When the road surface condition is good, sharp handling up to a high vehicle speed (in a state where the steering angle ratio is large) may be preferable. For a driver with high driving skill, a steering angle ratio characteristic set in advance corresponding to the vehicle speed and It is desirable to be able to set different steering angle ratio characteristics at the driver's will.
[0005]
The present invention has been made to solve such a problem, and the object thereof is to freely select a plurality of steering angle ratio modes by the operation of the driver, and to perform optimal steering according to the driving skill of the driver. The object is to provide a variable steering angle ratio steering device.
[0006]
[Means for Solving the Problems]
  In order to solve the above problems, a variable steering angle ratio steering apparatus according to the present invention includes a variable steering angle ratio mechanism, a control unit, an electric motor, and a steering angle ratio sensor. It is provided integrally with the steering gear box that houses the and pinion mechanism. Further, a switch means that is manually operated by the driver is provided, and the control means includes a target rudder angle ratio setting means for setting a plurality of target rudder angle ratio modes, and a target rudder angle ratio based on mode setting information from the switch means. Provided with mode selection means for selecting a modeThe mode selection means includes delay means for increasing the time required to reach the target rudder angle ratio signal in the switched target rudder angle ratio mode as the vehicle speed signal increases. The difference between the target rudder angle ratio signal in the rudder angle ratio mode and the target rudder angle ratio signal in the target rudder angle ratio mode before switching increases as the vehicle speed signal increases.It is characterized by that.
[0007]
  In the variable steering angle ratio steering apparatus according to the present invention, the variable steering angle ratio mechanism is provided integrally with a steering gear box that houses the rack and pinion mechanism, and further includes switch means that is manually operated by the driver, and the control means is The driver includes a target rudder angle ratio setting means for setting a plurality of target rudder angle ratio modes and a mode selection means for selecting the target rudder angle ratio mode based on mode setting information from the switch means. A desired steering angle ratio can be selected by operating the vehicle even when the vehicle is stopped or traveling.The mode selection means includes delay means for increasing the time required to reach the target rudder angle ratio signal in the switched target rudder angle ratio mode as the vehicle speed signal increases. Since the difference between the target rudder angle ratio signal in the rudder angle ratio mode and the target rudder angle ratio signal in the target rudder angle ratio mode before switching increases as the vehicle speed signal increases, even if the rudder angle ratio is switched while the vehicle is running, The transient response up to the target steering angle ratio can be moderated, and even when the steering angle ratio is switched to the same steering angle ratio during operation of the steering wheel, the time until the switched steering angle ratio is increased as the vehicle speed increases.
[0014]
Furthermore, the switch means according to the present invention is characterized in that it is arranged on a handle.
[0015]
Since the switch means according to the present invention is disposed on the steering wheel, the steering angle ratio can be easily switched even while the driver is operating the steering wheel.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
The present invention provides a variable steering angle ratio steering device that can freely select a steering angle ratio according to the driving skill of a driver and obtain an optimum steering feeling.
[0017]
FIG. 1 is a basic configuration diagram of a variable steering angle ratio steering apparatus according to an embodiment of the present invention.
In FIG. 1, a variable steering angle ratio steering device 1 is engaged with a handle 2, a steering shaft 3, a universal joint 4, an input shaft 6 and an output shaft (pinion) 7 of a variable steering angle ratio mechanism 5, and a pinion of an output shaft 7. A rack shaft 8 and a steering wheel (steered wheel) 11 are provided.
[0018]
The variable steering angle ratio steering device 1 includes an electric motor 9 constituting a drive system of the variable steering angle ratio mechanism 5 and a sensor system of the variable steering angle ratio mechanism 5, and detects the actual steering angle ratio and is electrically A steering angle ratio sensor 10 that converts the actual steering angle ratio signal CJ and a vehicle speed sensor 12 that detects the vehicle speed of the vehicle and converts it to an electrical vehicle speed signal V are provided.
[0019]
Furthermore, the variable steering angle ratio steering device 1 includes a control unit 13 and a motor driving unit 14 that are control systems of the variable steering angle ratio mechanism 5, and drives the motor 9 to drive the actual steering angle ratio of the variable steering angle ratio mechanism 5. The actual steering angle ratio signal CJ detected by the steering angle ratio sensor 10 is fed back (negative feedback) to the control means 13 to form a feedback loop of the control system.
[0020]
Next, the operation of the variable steering angle ratio steering apparatus 1 will be described.
When the driver operates the steering wheel 2, a rotation angle (twist) according to the steering wheel angle is transmitted to the input shaft 6 of the variable steering angle ratio mechanism 5 via the steering shaft 3 and the universal joint 4.
[0021]
An outer periphery of the input shaft 6 includes a movable housing (not shown) that rotates at the center (O) while decentering the center (A) of the input shaft 6, and this movable housing is connected to an electric motor 9 (see FIG. (Not shown).
A displacement amount of the movable housing rotated by the worm gear is detected by the steering angle ratio sensor 10, and an electric signal corresponding to the displacement amount is supplied to the control means 13 as an actual steering angle ratio signal CJ of the variable steering angle ratio mechanism 5.
Further, an electric signal corresponding to the vehicle speed detected by the vehicle speed sensor 12 is supplied to the control means 13 as a vehicle speed signal V.
[0022]
The control means 13 is composed of various arithmetic means, processing means, memory, etc. based on a microprocessor, and generates a target steering angle ratio signal (CS) corresponding to the vehicle speed signal V supplied from the vehicle speed sensor 12, and this target The motor control signal VO is supplied to the motor drive means 14 based on the deviation (CS−CJ) between the steering angle ratio signal (CS) and the actual steering angle ratio signal CJ supplied from the steering angle ratio sensor 10.
Further, the control means 13 performs control so that the deviation (Cs-CJ) becomes 0 quickly.
[0023]
The control means 13 includes target steering angle ratio setting means for setting a plurality of target steering angle ratio modes, and mode selection means for selecting the target steering angle ratio mode, and mode setting supplied from the switch means 15 operated by the driver. The drive of the electric motor 9 is controlled by the target rudder angle ratio signal (CS) of the mode selected based on the information J.
Further, the control means 13 supplies the mode selection signal MS to the display means 17, and displays the target steering angle ratio mode selected by the driver.
[0024]
The motor driving means 14 is constituted by a bridge circuit composed of switching elements such as four FETs (field effect transistors) and insulated gate transistors (IGBT), and the motor 9 is based on a motor control signal VO supplied from the control means 13. Is driven by PWM (Pulse Width Modulation) to rotate the motor 9 forward or backward.
[0025]
The display means 17 includes a display driver, an audible display composed of a visual display composed of a display element such as an LED or LCD, an audio synthesis IC, an electro-acoustic converter such as a speaker, etc., and a mode supplied from the control means 13 The target rudder angle ratio mode selected by the driver in response to the selection signal MS is displayed by visual display or sound.
[0026]
The target rudder angle ratio signal (CS) defines a target ratio of the steered angle (β) of the steered wheels 11 with respect to the steering angle (α) of the steering wheel 2. For example, the target rudder angle ratio signal When the steering angle (α) is set to 60 degrees in a state where (CS) is set to 0.5, the turning angle (β) is a target value that is set to 30 degrees.
[0027]
The actual steering angle ratio signal (CJ) is a value that is actually embodied by the variable steering angle ratio mechanism 5 when the target steering angle ratio signal (CS) is set by the vehicle speed signal V. The steering wheel 2 Is the ratio of the actual turning angle (β) when the steering wheel 11 is steered by converting the rotational motion of the pinion of the output shaft 7 into the linear motion of the rack shaft 8 with respect to the actual steering angle (α). .
[0028]
The principle of the variable steering angle ratio mechanism 5 will be described with reference to FIG.
FIG. 2 is an explanatory view of the operating principle of the variable steering ratio mechanism according to the present invention.
In FIG. 2, point A is the rotation center of the input shaft 6, and the motor 9 is rotated by driving the motor 9 based on the target steering angle ratio signal (CS) corresponding to the vehicle speed signal V as already described. Can be moved in the X1 direction or the X2 direction.
[0029]
Point B is the center of rotation of the output shaft 7 and point C is decentered by a fixed distance from point B. If the relationship between point C and point B is compared to a stone mill, point C is the action point and point B is the millstone. Become the center.
Since the rotation of point A is transmitted to point C, if the distance from point B to point A is a and the distance from point B to point C is b, the relationship between steering angle α and pinion rotation angle γ is Represented.
The turning angle β = K * γ (K: constant).
[0030]
[Expression 1]
b * sinγ = (b * cosγ−a) * tanα
[0031]
FIG. 2 shows the case in which the steering wheel 2 is rotated in the clockwise direction (right steering), but the same relationship exists in the case of the counterclockwise direction (left steering).
The specific configuration of the variable rudder angle ratio mechanism 5 is known from Japanese Patent Application Laid-Open No. 7-257406, and will not be described in detail.
[0032]
FIG. 3 is a characteristic diagram of the rotation angle γ of the steering angle α-pinion of the variable steering ratio mechanism according to the present invention.
In FIG. 3, the rotation angle γ of the pinion with respect to the steering angle α is, for example, the ratio of the rotation angle γ of the pinion to the steering angle α at a distance a = aO (= 0) from the point B to the point A when the vehicle speed V is low. Is 1.
[0033]
When the vehicle speed is in the middle vehicle speed range, the ratio of the pinion rotation angle γ to the steering angle α (steering angle ratio) is a value smaller than 1 at a distance a = a1 from the point B to the point A.
[0034]
Further, in the high vehicle speed region, the ratio of the pinion rotation angle γ to the steering angle α (the turning angle ratio) is a value smaller than 1 at a distance a = a 2 from the point B to the point A.
[0035]
In this manner, the variable steering angle ratio mechanism 5 sets the pinion rotation angle γ (as a result, the steering angle β) with respect to the steering angle α to be smaller as the vehicle speed is increased from a low vehicle speed to a high vehicle speed. Characteristics can be obtained, and stable steering characteristics can be obtained at high vehicle speeds.
[0036]
The variable steering angle ratio mechanism 5 of this embodiment is a mechanism in which the steering angle ratio (steering angle β / steering angle α) also changes depending on the magnitude of the steering angle α. Accordingly, the steering angle ratio is controlled by controlling the value of the distance a shown in FIG. 2 (the distance between the rotation center A of the input shaft 6 and the rotation center B of the output shaft 7).
That is, the steering angle ratio sensor 10 supplies the actual value of the distance a to the control means 13 as the actual steering angle ratio signal (CJ), and the control means 13 determines the distance a at which the actual value of the distance a is determined by the vehicle speed. By controlling so that it may become an actual value, it controls so that an actual steering angle ratio signal (CJ) may become a target steering angle ratio signal (CS).
[0037]
The relationship between the target value aS (target distance signal) of the distance a (see FIG. 2) corresponding to the vehicle speed signal V is as shown in the normal mode (aSO) of the vehicle speed signal V-target distance signal aS characteristic diagram shown in FIG. As the vehicle speed signal V increases, the target distance signal aS also increases, and as a result, the target steering angle ratio signal (CS) decreases.
A conventional variable steering angle ratio steering device having a variable steering angle ratio mechanism has only a target distance signal aS (target steering angle signal CS) characteristic shown in a normal mode (aSO) uniquely determined with respect to the vehicle speed signal V. Have.
[0038]
FIG. 4 is a block diagram of a main part of an embodiment of the variable steering angle ratio steering device according to the present invention.
4, the variable steering angle ratio steering apparatus 1 includes a vehicle speed sensor 12, a control means 13, an electric motor driving means 14, an electric motor 9, a variable steering angle ratio mechanism 5, a steering angle ratio sensor 10, a switch means 15, and a display means 17. Prepare.
The vehicle speed sensor 12, the motor driving means 14, the motor 9, the variable steering angle ratio mechanism 5, the steering angle ratio sensor 10 and the display means 17 have already been described with reference to FIG.
[0039]
The control unit 13 includes a target steering angle ratio setting unit 21, a deviation calculation unit 22, a drive control unit 23, and a mode selection unit 24.
The target rudder angle ratio setting means 21 is composed of a memory such as a ROM, stores in advance the vehicle speed signal V-target distance signal aS characteristic data shown in FIG. 9, and the vehicle speed signal V and the mode supplied from the vehicle speed sensor 12 are stored. Based on the mode selection signal MS supplied from the selection means 24, the corresponding target steering angle signal CS (actually the target distance signals aSA to aSN) is read, and the target steering angle ratio signal CS is supplied to the deviation calculation means 22. .
[0040]
Note that the target steering angle ratio signal CS (aSA to aSN) is the normal mode target steering angle ratio signal CS (= aSO) in the initial state when the ignition switch is turned on and the variable steering angle ratio steering device 1 is activated. ).
[0041]
The deviation calculation means 22 has a subtraction function, and the target steering angle ratio signal CS (aSA to aSN) supplied from the target steering angle ratio setting means 21 and the actual steering angle ratio signal CJ supplied from the steering angle ratio sensor 10. A deviation ΔC (= CS−CJ) with respect to (actual value aJ of the distance a is actually calculated), and a deviation signal ΔC (= CS−CJ) is supplied to the drive control means 23.
[0042]
The drive control unit 23 includes a PID controller, a signal generation unit, and the like, and performs P (proportional) control, I (integral) control, and D (differential) control on the deviation signal ΔC supplied from the deviation calculation unit 22 to perform PID control. Based on the signal subjected to the above, a hybrid signal of the ON signal (VON), the OFF signal (VOF) and the PWM signal (VPWM) is generated and supplied to the motor drive means 14 as the motor control signal VO.
[0043]
The mode selection means 24 is composed of a memory such as a ROM, stores the mode setting information J-mode selection signal MS characteristic data in advance, and when the mode setting information J is supplied from the switch means 15, the corresponding mode selection is selected. The signal MS data is read, and the mode selection signal MS is supplied to the target steering angle ratio setting means 21 and the display means 17.
[0044]
The electric motor 9 is PWM-driven by the electric motor voltage VM supplied from the electric motor driving means 14, and a mechanical electric motor torque signal TM is supplied to the variable rudder angle ratio mechanism 5, and the distance a of the variable rudder angle ratio mechanism 5 (see FIG. 2). ) Is detected by the steering angle ratio sensor 10 and supplied to the control means 13 as the actual steering angle ratio signal CJ.
[0045]
FIG. 5 is a block diagram of the main part of an embodiment of the control means according to the present invention.
In FIG. 5, the target rudder angle ratio setting means 21 of the control means 13 includes a target rudder angle ratio mode A to a target rudder angle ratio mode N (21A to 21N) and a switching means 25 for storing a plurality of target rudder angle ratio signals. Prepare.
[0046]
In the target rudder angle ratio mode A to target rudder angle ratio mode N (21A to 21N), the vehicle speed signal V-target distance signal aS (aSA to aSN) characteristic data shown in FIG. Corresponding target distance signals aSA to aSN are provided to the switching means 25.
[0047]
The switching means 25 has a software-controlled switch (SWA to SWN) function, corresponds to the mode selection signal MS (MSA to MSN) supplied from the mode selection means 24, and sets the switches SWA to SWN in a break state (solid line). From the display side) to the make state (broken line display side), the target distance signals aSA to aSN corresponding to the mode selection signals MSA to MSN are supplied to the deviation calculating means 22 as the target steering angle signal CS.
In the present embodiment, as described above, if the target distance signal aS is determined, the target steering angle ratio signal CS is uniquely determined by the steering angle α, so the reference numeral 21 is expressed as target steering angle ratio setting means. .
[0048]
The mode selection means 24 includes code conversion means, and a mode selection signal converted according to mode setting information J (= JA to JN) output when the buttons A to N of the switch means 15 are operated. MS (MSA to MSN) is supplied to the switching means 25 and the display means 17, and the variable steering angle ratio mechanism 5 shown in FIG. 1 is set to the target steering angle ratio set by the buttons A to N of the switch means 15. Displayed on the display means 17.
[0049]
  In addition, the switch means 15 pushes corresponding to the number of target rudder angle ratio modes.BoIt is composed of a tongue switch and is arranged near the driver's seat so that it can be operated even while the driver is operating the steering wheel.
[0050]
As described above, the variable steering angle ratio steering apparatus 1 according to the present invention includes the switch unit 15 that is manually operated by the driver, and the control unit 13 sets the target steering angle ratio modes 21A to 21N. Since the setting means 21 and the mode selection means 24 for selecting the target rudder angle ratio mode based on the mode setting information J from the switch means 15 are provided, the driver operates the switch to perform a desired operation even when the vehicle is stopped or running. The rudder angle ratio can be selected.
[0051]
FIG. 6 is a block diagram showing the principal part of the mode selecting means according to the present invention.
In FIG. 6, the mode selection unit 24 includes a code conversion unit 27, a comparison unit 31, an inversion unit 32, and a switching unit 33.
[0052]
The code conversion means 27 comprises a memory such as a ROM, and corresponds to the mode setting information J (= JA to JN) supplied from the switch means 15, for example, a mode selection signal MS (MSA to MSN) converted to a binary code. ) Is provided to the switching means 33.
The mode selection signal MS (MSA to MSN) converted into a binary code is a signal for controlling the switches (SWA to SWN) of the switching means 25 shown in FIG.
[0053]
The comparison means 31 has a comparison function of soft control, compares the vehicle speed signal V with a preset low vehicle speed reference value VK, and when the vehicle speed signal V exceeds the reference value VK (V> VK), it is H. The level comparison signal H is supplied to the inverting means 32.
On the other hand, the comparison means 31 supplies an L level comparison signal H to the inverting means 32 when the vehicle speed signal V is equal to or lower than the reference value VK (V ≦ VK).
[0054]
The inversion means 32 has an inverter function, inverts the comparison signal H supplied from the comparison means 31, and provides the inversion signal SO to the switching means 33.
[0055]
The switching means 33 has a soft control switch function. Based on the inversion signal SO supplied from the inversion means 32, when the inversion signal SO is at the H level, the switch is set to the make state and the mode from the code conversion means 27 is set. The selection signal MS (MSA to MSN) is supplied to the switching means 25 shown in FIG. 5 to select the target steering angle ratio signal CS (aSA to aSN) corresponding to the mode selection signal MS (MSA to MSN).
[0056]
Further, when the inverted signal SO is at the L level, the switching means 33 sets the switch to a break state and supplies the mode selection signal MS (MSA to MSN) from the code conversion means 27 to the switching means 25 shown in FIG. Is prohibited.
[0057]
As described above, the mode selection means 24 according to the present invention provides the target steering angle ratio corresponding to the mode setting information J (= JA to JN) from the switch means 15 when the vehicle speed signal V is equal to or lower than the low vehicle speed reference value VK. Since the mode is selected, the driver can perform a switch operation to select a desired steering angle ratio when the vehicle is stopped or when the vehicle speed is equal to or lower than the reference value of the low vehicle speed.
Further, when the vehicle speed signal V exceeds the low vehicle speed reference value VK, the mode selection means 24 invalidates the selection of the target steering angle ratio mode even if the switch means 15 is operated.
[0058]
FIG. 7 is a block diagram of a main part of an embodiment of the delay means according to the present invention.
In FIG. 7, the delay unit 35 includes a timer unit 36 and a delay characteristic calculation unit 37.
The timer means 36 has a variable timer function obtained by dividing the reference clock of the control means 13, generates a timer signal TO corresponding to the vehicle speed signal V, and supplies the timer signal TO to the delay characteristic calculation means 37.
The timer means 36 generates a timer signal TO having a corresponding (proportional) length as the vehicle speed signal V increases.
[0059]
The delay characteristic calculation means 37 includes a memory, a subtraction function, a division function, and the like. When the switch means 15 is selected, the target steering angle ratio signal CS (aSA to aSN) from the target steering angle ratio setting means 21 is the current signal ( For example, when the target distance signal aSO) is switched to a new value (for example, the target distance signal aSN) (aSO → aSN), the time to reach the target distance signal aSN is delayed according to the timer signal TO. The target steering angle ratio signal CS (T) is output.
[0060]
FIG. 10 is a delay characteristic diagram of the delay means according to the present invention.
In FIG. 10, the target distance signal aS sets a longer time to reach the target distance signal aSN from the target distance signal aSO as the timer signal TO increases.
[0061]
For example, when the timer signal is T01, the slope of the target distance signal aS is set to (aSN-aSO) / T01, and when the timer signal is T04, the slope of the target distance signal aS is set to (aSN-aaSO) / T04. Thus, the transient response can be moderated in proportion to the timer signal TO.
[0062]
In this embodiment, the delay characteristic is a straight line, but may be an exponential function.
[0063]
As described above, the mode selection unit 24 according to the present invention delays the time until the target steering angle ratio signal (target distance signal aS) in the target steering angle ratio mode is reached corresponding to the vehicle speed signal V. Therefore, even if the steering angle ratio mode is switched while the vehicle is traveling, the transient response up to the target steering angle ratio can be moderated.
[0064]
Further, the delay means 35 according to the present invention lengthens the time until the vehicle reaches the target steering angle ratio signal (target distance signal aS) as the vehicle speed signal V increases. Even if the ratio is switched, the time until the switched steering angle ratio can be increased as the vehicle speed increases.
[0065]
FIG. 8 is a layout view of an embodiment of the switch means according to the present invention.
The switch means is arranged on the handle, (a) the figure shows the arrangement of the three push button switches, and (b) the figure shows the arrangement of the two up / down switches.
[0066]
(A) In the figure, the switch means 41 has push button switches 41A, 41B, 41C arranged on the spokes of the circular handle 40, and one target rudder corresponding to each push button switch 41A, 41B, 41C. An angular ratio signal CS (for example, aSA to aSC) can be selected.
[0067]
On the other hand, in FIG. 4B, the switch means 43 arranges two switches, a down switch 43A and an up switch 43B, and an electronic volume (not shown) on the spoke part of the circular handle 42, and pushes the down switch 43A or the up switch 43B. By continuing, a plurality of target steering angle ratio signals CS (for example, aSA to aSN) can be selected.
[0068]
FIG. 11 is a diagram for explaining the operation of the up / down switch according to the present invention.
In FIG. 11, when the up switch 43B is pressed after the key pressing time t = 0, the mode setting information J is switched from JO to JB after a predetermined time TC has elapsed.
Further, if the up switch 43B is continuously pressed, the mode setting information J is switched from JB to JA after a predetermined time 2TC has elapsed.
[0069]
When the down switch 43A is pressed when the mode setting information J is JA, the mode setting information JB is obtained at time TC and the mode setting information JO is obtained at time 2TC.
[0070]
Thus, by providing two up / down switches, a plurality of target steering angle ratio signals CS (for example, aSA to aSN) can be selected.
Further, since the switch means 41 and 43 are disposed on the handles 40 and 42, the steering angle ratio can be easily switched even when the driver operates the handle.
[0071]
【The invention's effect】
As described above, the variable steering angle ratio steering apparatus according to the present invention includes the switch means that is manually operated by the driver, and the control means includes the target steering angle ratio setting means that sets a plurality of target steering angle ratio modes. In addition, a mode selection unit that selects a target steering angle ratio mode based on mode setting information from the switch unit is provided, and the driver can select a desired steering angle ratio even when the vehicle is stopped or running by operating a switch. Therefore, it is possible to provide optimum steering characteristics for beginners to drivers with high driving skills according to the driving environment.
[0072]
Further, the mode selection means according to the present invention selects the target steering angle ratio mode corresponding to the mode setting information from the switch means when the vehicle speed signal is equal to or lower than the reference value of the low vehicle speed, and the state where the vehicle is stopped or the vehicle speed is When the vehicle speed is equal to or lower than the reference value of the low vehicle speed, the driver can select a desired steering angle ratio by operating a switch, so that the steering characteristics can be changed reliably in a stable driving situation.
[0073]
Furthermore, the mode selection means according to the present invention comprises delay means for delaying the time until the target steering angle ratio signal (target distance signal) in the target steering angle ratio mode is reached in response to the vehicle speed signal, so that the vehicle travels. Even if the rudder angle ratio is switched, the transient response up to the target rudder angle ratio can be moderated, preventing a sudden change in the steering characteristics associated with the change of the rudder angle ratio. Improvements can be made.
[0074]
Further, the delay means according to the present invention increases the time required to reach the target steering angle ratio signal (target distance signal) as the vehicle speed signal increases, and even if the steering wheel is operated to switch to the same steering angle ratio. As the vehicle speed increases, the time required to reach the switched steering angle ratio can be lengthened, so that a sudden change in steering characteristics associated with a change in the steering angle ratio can be prevented, and the steering feeling can be improved.
[0075]
Furthermore, since the switch means according to the present invention is arranged on the handle and the driver can easily switch the steering angle ratio even while operating the handle, the operability and convenience at the time of switching the steering angle ratio are improved. be able to.
[0076]
Therefore, the optimum steering performance can be provided for a driver with a high driving skill from a beginner, and a variable steering angle ratio steering device excellent in operability and convenience for switching the steering angle ratio can be provided.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a variable steering angle ratio steering apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operating principle of the variable steering ratio mechanism according to the present invention.
FIG. 3 is a characteristic diagram of the rotation angle γ of the steering angle α-pinion of the variable steering ratio mechanism according to the present invention.
FIG. 4 is a block diagram of a main part of an embodiment of a variable steering angle ratio steering device according to the present invention.
FIG. 5 is a block diagram of the main part of an embodiment of the control means according to the present invention.
FIG. 6 is a block diagram of a main part of an embodiment of mode selection means according to the present invention.
FIG. 7 is a block diagram of a main part of an embodiment of delay means according to the present invention.
FIG. 8 is a layout view of an embodiment of switch means according to the present invention.
FIG. 9 is a characteristic diagram of a vehicle speed signal V-target distance signal aS according to the present invention.
FIG. 10 is a delay characteristic diagram of the delay means according to the present invention.
FIG. 11 is an explanatory diagram of an up / down switch according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Variable steering angle ratio steering apparatus, 2, 40, 42 ... Handle, 5 ... Variable steering angle ratio mechanism, 6 ... Input shaft, 7 ... Output shaft (pinion), 8 ... Rack shaft, 9 ... Electric motor, 10 ... Rudder Angle ratio sensor 11 ... Steering wheel, 12 ... Vehicle speed sensor, 13 ... Control means, 14 ... Electric motor drive means, 15, 41, 43 ... Switch means, 17 ... Display means, 21 ... Target rudder angle ratio setting means, 21A 21N: Target steering angle ratio modes A to N, 22: Deviation calculation means, 23: Drive control means, 24: Mode selection means, 25, 33 ... Switching means, 27 ... Sign conversion means, 31 ... Comparison means, 32 ... Inversion means, 35 ... delay means, 36 ... timer means, 37 ... delay characteristic calculation means, 41A, 41B, 41C ... push button switch, 43A ... down switch, 43B ... up switch.

Claims (2)

A variable rudder angle ratio mechanism that can vary a rudder angle ratio that is a ratio of a steered wheel steer angle and a steering wheel steer angle, and a target rudder angle ratio signal corresponding to a vehicle speed signal detected by a vehicle speed sensor, Control means for controlling the driving of the electric motor based on the target rudder angle ratio signal, the electric motor for driving the variable rudder angle ratio mechanism to vary the rudder angle ratio, and an actual value determined by the variable rudder angle ratio mechanism In a variable steering angle ratio steering apparatus comprising: a steering angle ratio sensor that detects a steering angle ratio signal and feeds back the actual steering angle ratio signal to the target steering angle ratio signal.
The variable rudder angle ratio mechanism is provided integrally with a steering gear box that houses a rack and pinion mechanism,
Further, a switch means that is manually operated by a driver is provided, and the control means includes a target rudder angle ratio setting means for setting a plurality of target rudder angle ratio modes, and a target rudder based on mode setting information from the switch means. Comprising mode selection means for selecting an angle ratio mode ;
The mode selection means includes delay means for increasing the time until the target steering angle ratio signal in the switched target steering angle ratio mode reaches the target steering angle ratio signal, as the vehicle speed signal increases,
The difference between the target rudder angle ratio signal in the switched target rudder angle ratio mode and the target rudder angle ratio signal in the target rudder angle ratio mode before switching increases as the vehicle speed signal increases. Steering angle ratio steering device.   The variable steering angle ratio steering apparatus according to claim 1, wherein the switch means is disposed on a handle.

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