JP2004359000A - Steering system for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a vehicular steering device capable of certainly informing a system abnormal condition to a driver, and urging the driver to carry a vehicle in a service center, when a failure or a malfunction occurs in a system. <P>SOLUTION: When a failure detecting means 9 detects a failure of a member constituting a steer-by-wire type steering device, a reaction coefficient is increased by a reaction coefficient setting means 27, and a reaction force making the operation of a steering wheel heavy is gradually applied from a reaction generating motor 5 on a steering wheel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for notifying a driver of a failure that occurs in a vehicle steering system.
[0002]
[Prior art]
As a conventional technique, a system with a warning lamp mechanism in an electric power steering system is known. The purpose of this is to make a warning lamp emit when an abnormality occurs in the system, and to inform the driver that the abnormality has occurred.
Further, for example, there is one that issues an alarm when a vehicle is about to deviate from a traveling lane due to a driver falling asleep (see Patent Document 1). This detects a lane (white line) on the road by the TV camera and gives a warning to the driver when the vehicle tries to deviate from the lane. At the time of a warning, the steering shaft of the steering wheel is directly vibrated by the vibration actuator built in the steering wheel (operator).
[0003]
In addition, a method has been reported in which the driver's drowsiness and drunkness are detected from the steering conditions and various detection devices provided on the vehicle body, and a warning motor is used to vibrate the steering shaft to warn the driver. (See Patent Document 2).
In addition, when the driver actively steers and intends to change course, an electric power steering apparatus that performs preventive safety control that avoids a danger state that can occur mainly due to the driver's intention is performed. And a danger prediction means for predicting danger due to the approach of an obstacle as a preventive safety device, and when a danger is predicted by the danger prediction means, a warning is issued by vibrating a steering wheel and periodically changing a target control value. It is also reported that a warning control means is provided (see Patent Document 3). As an example of a means for detecting a failure, a method for detecting an ON failure of an FET used for a motor driving means has been reported (see Patent Document 4).
[0004]
[Patent Document 1]
JP-A-6-76200 (pages 2 to 4, FIG. 3)
[Patent Document 2]
US Pat. No. 5,709,281 [Patent Document 3]
JP-A-8-175413 (pages 3 to 7, FIG. 4)
[Patent Document 4]
JP-A-2000-152691 (pages 2 to 5, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, although a technology for simply notifying or warning a failure has been reported in the past, for a failure that can be operated but needs repair, for example, for a failure of a steering angle detection unit or a torque sensor, etc. In addition, there is no notification or warning of a failure that effectively promotes bringing a vehicle to a service center or the like that performs repair or inspection of the failure.
An object of the present invention is to provide a steering device for a vehicle that can effectively encourage a driver to bring a vehicle to a service center or the like when a failure or malfunction occurs in a system or device.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an operator operated by a driver for steering a vehicle, an electric motor driven according to an operation amount of the operator, and a steered wheel driven by driving the electric motor. A steering device for a vehicle having a steering mechanism, comprising: operating force increasing means for gradually increasing a force required for operating the operating element when a failure of a member constituting the steering device is detected. Features.
This makes it possible to notify the driver of the system failure or abnormality reliably due to the heavy operation of the operator (steering wheel operation), and to promptly take a corresponding measure.
[0007]
Further, the vehicle includes an operator operated by the driver for steering the vehicle, an electric motor driven in accordance with the operation amount of the operator, and a steering mechanism for driving steered wheels by driving the electric motor. The steering device is characterized by comprising sporadic current generating means for sporadically flowing a current to an electric motor mechanically connected to the operation member when a failure of a member constituting the steering device is detected.
As a result, a pulse-like impact is given to the operator, so that the driver can be reliably informed of the system failure or abnormality, and a corresponding measure can be taken earlier. The electric motor mechanically connected to the operation element is a steering angle generation motor or a reaction force generation motor described later.
[0008]
The sporadic current generating means gradually increases the value of the sporadic current.
As a result, a pulse-like impact is applied to the operator while being gradually increased, so that the driver can be reliably notified of the system failure or abnormality, and a corresponding measure can be taken earlier.
[0009]
A steering apparatus for a vehicle, comprising: an operator operated by a driver for steering a vehicle; an electric motor driven in accordance with an operation amount of the operator; and a steering mechanism that drives steered wheels by driving the electric motor. A dead zone where the output of a motor mechanically connected to the operation element is set to 0 at and near the position where the operation amount of the operation element is neutral, and a failure of a member constituting the steering device is detected. Sometimes, there is provided a dead zone enlarging means for gradually increasing the width of the dead zone.
As a result, the width of the dead zone corresponding to the play of the steering wheel is increased near the straight traveling, and by noticing this, the driver can be notified of the system failure or abnormality, and the corresponding action can be taken earlier. . The “dead zone” includes, for example, a dead zone where the output of the reaction force generating motor described below is set to 0 and a dead zone where the output of the steering angle generating motor described below is set to 0. The phrase “set the output of the motor to 0” is not limited to the case where the output of the motor is literally set to 0, but also includes, for example, the case where the output is low enough that the driver does not feel the output of the motor.
[0010]
The dead zone expanding means widens the dead zone when the vehicle speed is low and narrows the width when the vehicle speed is high.
According to this, since the width of the dead zone is widened at the time of low-speed operation, it is possible to make the driver easily notice a failure or an abnormality of the system at a low speed. On the other hand, it is possible for the driver to easily concentrate on driving at high speed. Note that the low speed includes the vehicle speed 0 in consideration of the stationary operation.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a vehicle steering device (hereinafter, referred to as a “steering device”) according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
[First Embodiment]
FIG. 1 shows a schematic structural diagram of a steering device according to an embodiment of the present invention.
With reference to FIG. 1, the overall structure of a steering device according to an embodiment of the present invention will be described.
The steering device 1 is a steering device that performs steering by steer-by-wire (SBW; Steer By Wire), and includes a steering angle detecting means 4 provided on a steering shaft 3 connected to an operator (handle) 2, and a reaction force. The motor comprises a generating motor 5 and a torque sensor 6, a vehicle speed detecting means 7, a failure detecting means 9, a steering angle generating motor (electric motor) 11, a tire angle detecting means 12, and an ECU (control device) 10. . The “steering mechanism” in the claims is constituted by the rack shaft 14 and the like.
[0013]
The reaction force generation motor 5 applies a steering reaction force to the operator 2. The steering reaction force is controlled by a target current according to the magnitude of the tire angle deviation supplied from the ECU 10 (reaction motor target current setting means 29). It is configured to be given.
[0014]
The vehicle speed detection means 7 supplies a signal relating to the vehicle speed V to the ECU 10 using a vehicle speed sensor (not shown).
The steering angle generating motor 11 drives the rack shaft 14 based on a steering drive signal output from the ECU 10 to steer the steered wheels T. The tire angle accompanying the rotation of the steering angle generating motor 11 is detected by the tire angle detecting means 12 and is returned to the ECU 10.
The tire angle detecting means 12 can be constituted by a rack position sensor or the like for detecting the position of the rack shaft 14.
[0015]
The failure detecting means 9 is various monitoring means provided in each part of the system, and an example thereof is shown in Patent Document 4.
[0016]
FIG. 2 is a block diagram of the ECU of the steering device according to the embodiment of the present invention and main functions in the vicinity thereof.
In FIG. 2, the steering device 1 includes a steering angle detecting means 4, a reaction force generating motor 5, a torque sensor 6, a vehicle speed detecting means 7, a failure detecting means 9, an ECU 10, a steering angle generating motor 11, a tire angle detecting means 12, And a steering angle generating motor driving unit 24 and a reaction force motor driving unit 30.
The ECU 10 also includes a tire angle command value generation unit 21, a deviation calculation unit 22, a drive control unit 23, a failure determination unit 26, a reaction force coefficient setting unit 27, a target reaction force setting unit 28, and a reaction motor target current setting unit. 29. The "operation force increasing means" in the claims is constituted by a reaction force coefficient setting means 27 and the like.
[0017]
The tire angle command value generation unit 21 is configured by a memory such as a ROM, and stores steering torque (or steering angle) data using the vehicle speed signal supplied from the vehicle speed detection means 7 as a parameter and tire angle command value generation unit characteristic data. In advance, when the vehicle speed signal and the steering torque signal are supplied, the corresponding tire angle command value generation unit characteristic data is read, and the target tire angle signal is supplied to the deviation calculating means 22.
The deviation calculating means 22 has a subtraction function, calculates a deviation between the target tire angle signal and the actual tire angle signal supplied from the tire angle detecting means 12, and inputs the tire angle deviation signal to the drive control means 23.
[0018]
The drive control means 23 includes a PID (proportional / integral / differential) controller (not shown), a signal generating means, and the like. The drive control means 23 performs PID control on the tire angle deviation signal from the deviation calculating means 22, and then performs PWM (pulse width modulation). A motor drive control signal, which is a composite signal of a signal, an ON signal, and an OFF signal, is generated and supplied to the steering angle generation motor drive means 24.
The tire angle deviation signal from the deviation calculating means 22 is also supplied to a torsion bar coefficient changing unit 25 for generating a reaction force of the virtual torsion bar on the operator 2.
The torsion bar coefficient changing unit 25 performs virtual torsion bar control using the tire angle deviation signal as a parameter using the vehicle speed signal supplied from the vehicle speed detecting unit 7, and then inputs the signal to the target reaction force setting unit 28. The target reaction force setting means 28 sets the magnitude of the reaction force applied to the steering shaft 3 by the reaction force generation motor 5 based on the control-converted tire angle deviation signal, and sends it to the reaction force motor target current setting means 29. .
[0019]
The failure detection means 9 monitors each part of the system and sends the data to the failure determination means 26. Here, each part of the system is a member that constitutes the steering device 1, and includes, for example, sensors (steering angle detecting means 4, torque sensor 6, vehicle speed detecting means 7,...), Electric motor (steering angle generating motor 11), electric motor , An electronic circuit, a computer (ECU 10), and the like.
[0020]
The failure determination means 26 performs a failure determination based on the data from the failure detection means 9, and when it determines that a failure is to be reported, drives the reaction force coefficient setting means 27 and outputs the reaction force motor target current setting means 29. The value of the force motor target current is multiplied by a predetermined reaction force coefficient α. The reaction force coefficient α gradually increases to a certain maximum value as time passes, as shown in FIG. It is preferable that the maximum value of the reaction force coefficient α be set within a range in which the reaction force can drive the vehicle, from the viewpoint that the driver himself brings the vehicle to a service center or the like. This is because, if the reaction force that allows driving is exceeded, the driver cannot drive the vehicle and bring it to a service center or the like.
[0021]
The reaction motor target current value output from the reaction motor target current setting unit 29 is applied to the reaction motor driving unit 30, and the reaction motor driving unit 30 drives the reaction generating motor 5 and responds to the current value. The applied reaction force is applied to the steering shaft 3 in a direction opposite to the steering direction performed by the driver.
[0022]
Thus, the reaction force coefficient gradually increases as time elapses after the failure is detected. Therefore, the driver feels that the reaction force gradually increases and the movement of the operator 2 gradually increases, so that the driver can know the failure. Incidentally, the movement of the operation element 2 is felt to be heavy when the driver operates the operation element 2 and cannot be felt when the operation is not performed. The movement of the operation element 2 may be increased by reducing the current supplied to the steering angle generation motor 11 (the reaction force may be increased).
[0023]
When the reaction force is gradually increased in this manner, the driver gradually increases the force required for steering. Therefore, it is possible to effectively encourage the driver to bring the vehicle to a service center for vehicle repair or the like. In the case of minor failures (repairs are necessary but not enough to make driving impossible), the driver often does not readily bring the vehicle in for repair, making driving impossible. In many cases, the service center is contacted afterwards. According to the present embodiment, such cases can be reduced, and it is possible to effectively promote bringing a vehicle to a service center or the like before the breakdown becomes serious, so that both the service center and the driver can use the vehicle. convenient. Incidentally, in the case of the steering device 1 of the present embodiment in which the steering wheel 2 and the steered wheels T are separated, if the steering angle generating motor 11 stops operating due to a failure, the driving becomes impossible. Also, in the case of an electric power steering device that assists the driver's manual steering force with the power of an assist motor, recent vehicles have become larger and heavier, tires have become wider, etc. The fact is that driving becomes impossible. According to the present invention, in such a vehicle, it is possible to promote bringing the vehicle to a service center or the like before driving becomes impossible.
[0024]
[Second embodiment]
Next, a second embodiment according to the present invention will be described. FIG. 4 is a block diagram of an ECU according to a second embodiment of the present invention and main functions around the ECU. FIG. 4 differs from FIG. 2 in that a pulse signal generator 31 is provided in a stage subsequent to the failure determination means 26 in place of the reaction force coefficient setting means 27. Therefore, the same reference numerals as in the first embodiment denote the same elements as those in the first embodiment, and a description thereof will be omitted. In addition, FIG. 1 used in the first embodiment is appropriately referred to in the second embodiment. The "sporadic current generating means" in the claims is constituted by the pulse signal generator 31 and the like.
[0025]
In this embodiment, when a failure is detected, the failure determination means 26 operates the pulse signal generator 31, and a pulse from the pulse signal generator 31 is input to the reaction force motor target current setting means 29, and left and right. Is applied to the operator 2. When the reaction force is applied in a pulsed manner, the driver is more likely to notice the shock of the reaction force. The pulse-like reaction force may be applied when the driver is operating the operator 2 (during steering), or may be applied regardless of whether the driver has operated the operator 2. It may be.
[0026]
Furthermore, a method of gradually increasing this pulse-like reaction force with time (see FIG. 3) is also conceivable. FIG. 5 shows a time chart of the reaction torque current (right torque current / left torque current) in this case. In this case, the pulse interval was set to 2 seconds. Corresponding to FIG. 3, the torque current increases with the passage of time, which can effectively encourage the driver to bring the vehicle to a service center or the like.
[0027]
The pulse signal generator 31 counts the number of times that the ignition is turned on (accumulates the number of IGons), and gradually increases the magnitude of the pulse-like reaction force in a stepwise manner according to the count value (IG function). You can also go. FIG. 6 shows a time chart of the reaction torque current (right torque current / left torque current) in this case. As shown in FIG. 6, as the cumulative number of IGons increases, the pulse reaction current (reaction torque current) increases. Therefore, it is possible to effectively encourage the driver to bring the vehicle to a service center or the like. Instead of the IG function, the magnitude of the pulse-like reaction force (reaction torque current) may be gradually increased every time the steering angle changes by a certain angle.
[0028]
This process of varying the reaction force in a pulse manner is not executed simultaneously with the occurrence of an error, but is started by the pulse signal generator 31 at the same time as the occurrence of the error, and the error is detected again after a certain grace period has elapsed. Then, a pulse-like reaction force change may be started thereafter. By doing so, it is possible to prevent malfunction due to erroneous detection of the failure detecting means 9.
[0029]
[Third embodiment]
Next, a third embodiment according to the present invention will be described. FIG. 7 shows a block diagram of the ECU of the third embodiment and the main functions around it. FIG. 7 differs from FIGS. 2 and 4 in that a play width control means 32 is provided downstream of the failure determination means 26. For this reason, elements having the same features as those of the first and second embodiments are denoted by the same reference numerals as those of the first and second embodiments, and the description thereof is omitted. In addition, FIG. 1 used in the first embodiment is appropriately referred to in the third embodiment. The "dead zone enlarging means" in the claims is constituted by the play width control means 32 and the like.
[0030]
In this embodiment, when a failure is detected by the failure detection unit 9, the failure determination unit 26 determines a failure and inputs a failure determination signal to the play width control unit 32. The play width control means 32 is provided when the steering angle with respect to the neutral position of the operation element 2 detected by the steering angle detection means 4 is smaller than a predetermined amount (at or near the position where the operation amount of the operation element 2 becomes the neutral position). Has a function of making the reaction force generated by the reaction force generating motor 5 by acting on the target reaction force setting means 28, that is, a so-called play (dead zone) of the operator 2. Then, when the failure determination signal is input, the range of the predetermined amount of the steering angle (the range of play) for reducing the reaction force to 0 is gradually widened within the range of the preset limit value.
FIG. 8 is a graph showing the relationship between the steering angle and the reaction force. FIG. 8A shows the relationship between the steering angle and the reaction force when no play (dead zone) is provided, and FIG. 8B shows the relationship between the steering angle and the reaction force when the play (dead zone) is provided. It is. When the portion of the play (dead zone) where there is no steering reaction force gradually widens in this way, the driver is likely to feel uncomfortable and easily notice that there is a malfunction or a defect.
This can effectively encourage the driver to bring the vehicle to a service center or the like.
The play (dead zone) is provided when the vehicle is stationary and the vehicle speed is 0, or when the vehicle speed is low or medium. However, when the vehicle speed is high, it is better to concentrate on driving the driver. As shown in FIG. 8B, no play (dead zone) is provided (or play is minimized). If the play (dead zone) is too wide, the driving operation becomes impossible. Therefore, a limit value of the play (dead zone) range is set in advance so that the width of the play (dead zone) is not further increased. This play may be provided on the reaction force generation motor 5 side or on the steering angle generation motor 11 side.
[0031]
Although the present invention has been described in connection with the embodiments, the present invention is not limited to this, and various measures can be considered without departing from the spirit of the present invention. For example, in the embodiment, the failure is notified to the driver via the reaction force generating motor 5, but a dedicated actuator and a motor are provided around the steering wheel as a dedicated vibration exciter to control the same. The driver may be notified of the malfunction. In addition, by appropriately combining the above-described processes of varying the reaction force in the form of a pulse, the presence of the pulse can be made clearer. Further, the interval between pulses in the pulse signal generator 21 may be shortened in accordance with the elapsed time or the IG function, thereby prompting the driver to bring the vehicle to a service center.
[0032]
In addition, for example, the “going” and “returning” of the operation element 2 are determined, and the reaction force is increased by the reaction force coefficient setting means 27 or the reaction force motor target current setting means 29 when the operation element 2 is “going”. When the steered wheel T (operator 2) is "returned" to the neutral state by the self-aligning torque, the reaction force is made normal (the reaction force coefficient α = 1 in FIG. 3), and the Preferably, the return is normal. The return control based on the self-aligning torque can be applied to both a steer-by-wire device and an electric power steering device. Incidentally, "going" is when the direction of the steering torque and the rotation direction of the steering angle generating motor 11 are the same, and "return" is when the direction of the steering torque and the rotating direction of the steering angle generating motor 11 are different. This return control can also be applied to the embodiment that provides a pulse.
[0033]
Note that a steer-by-wire steering control method with a mechanical backup function is known. In the steer-by-wire system with a mechanical backup function, the steering element and the steering mechanism are mechanically separated in a normal state, and the steer-by-wire steering system in which the steered wheels T are driven by an electric steering mechanism. Although control is being performed, if a malfunction occurs in the electric control system such as the ECU, a mechanical link mechanism operates so that steering can be performed with a mechanical configuration, and a steer-by-wire system is used. It is a form to back up the steering.
If a redundant system is configured in the system as in this method, etc., it was conventionally difficult to intentionally inform the driver of a system failure state even when the system is partially failed, In the present embodiment, it is possible to effectively inform the driver of the failure and to effectively bring the vehicle to a service center or to contact the service center or the like before the breakdown becomes serious.
[0034]
【The invention's effect】
According to the present invention, when a failure or abnormality occurs in the system by giving a reaction force or vibration to the operator, it is possible to reliably notify the driver of the failure or abnormality. It is possible to effectively promote bringing a vehicle to the airport. According to the first aspect of the present invention, the driver can be informed of the system abnormality or the like by the operating force. In the second aspect of the invention, the driver can be informed of the system abnormality or the like by the pulse. Thus, the driver can be notified of a system abnormality or the like.
[Brief description of the drawings]
FIG. 1 is a schematic structural view of a steering device according to an embodiment (first to third) of the present invention.
FIG. 2 is a block diagram of an ECU (control device) of the steering device according to the first embodiment of the present invention and main functions in the vicinity thereof.
FIG. 3 is a diagram illustrating a temporal increase in a reaction force coefficient.
FIG. 4 is a block diagram of an ECU according to a second embodiment of the present invention and main functions around the ECU.
FIG. 5 is a diagram showing a time chart of a temporal increase of a pulse-like reaction force.
FIG. 6 is a diagram showing a time chart of a temporal increase in a pulse-like reaction force different from that in FIG. 5;
FIG. 7 is a block diagram of main functions of an ECU according to a third embodiment of the present invention and peripheral components thereof;
FIG. 8 is a graph showing a relationship between a steering angle and a reaction force.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Operator (handle), 3 ... Steering axis, 4 ... Steering angle detecting means, 5 ... Reaction force generating motor, 6 ... Torque sensor, 7 ... Vehicle speed detecting means, 8 ... Yaw rate detecting means, 9 ... failure detection means, 10 ... ECU (control device), 11 ... steering angle generation motor, 12 ... tire angle detection means, 14 ... rack shaft, 21 ... tire angle command value generation unit, 22 ... deviation calculation means, 23 ... drive Control means, 24: steering angle generating motor driving means, 25: torsion bar coefficient changing unit, 26: failure determination means, 27: reaction force coefficient setting means, 28: target reaction force setting means, 29: reaction force motor target current setting Means, 30 ... reaction motor driving means, 31 ... pulse signal generator, 32 ... play width control means

Claims (5)

A steering apparatus for a vehicle, comprising: an operator operated by a driver for steering a vehicle; an electric motor driven in accordance with an operation amount of the operator; and a steering mechanism that drives steered wheels by driving the electric motor. At
A steering device for a vehicle, comprising: an operating force increasing means for gradually increasing a force required for operating the operation element when a failure of a member constituting the steering device is detected. A steering apparatus for a vehicle, comprising: an operator operated by a driver for steering a vehicle; an electric motor driven in accordance with an operation amount of the operator; and a steering mechanism that drives steered wheels by driving the electric motor. At
A steering device for a vehicle, comprising: sporadic current generating means for sporadically flowing a current to an electric motor mechanically connected to the operation element when a failure of a member constituting the steering device is detected. . 3. The vehicle steering apparatus according to claim 2, wherein the sporadic current generation unit gradually increases the current value flowing sporadically. A steering apparatus for a vehicle, comprising: an operator operated by a driver for steering a vehicle; an electric motor driven in accordance with an operation amount of the operator; and a steering mechanism that drives steered wheels by driving the electric motor. At
A dead zone where the output of a motor mechanically connected to the manipulator is set to 0 at a position where the operation amount of the manipulator is neutral and the vicinity thereof is provided when a failure of a member constituting the steering device is detected. And a dead zone expanding means for gradually increasing the width of the dead zone. The steering apparatus for a vehicle according to claim 4, wherein the dead zone expanding unit widens the dead zone when the vehicle speed is low and narrows the width when the vehicle speed is high.

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