JP2003165451A - Power steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain steering operation without giving uncomfortable feeling to a driver at the time of system failure in a motor-driven power steering mechanism. <P>SOLUTION: A first steering angle detection means detects a steering angle θH<SB>1</SB>of a steering wheel 5, a second steering angle detection means 2 detects a real steering angle θH<SB>2</SB>of a wheel, and an electric motor 7 drives a steering mechanism 6 so that the real steering angle θH<SB>2</SB>may be a target steering angle θ<SB>2</SB>' corresponding to the steering angle θH<SB>1</SB>. A twist member 3 provided between the steering wheel 5 and the steering mechanism 6 permits a twist within a limit up to a prescribed angle. In case of the system failure, the twist more than the prescribed angle is not permitted, thus driving the steering mechanism 6 corresponding to the operation of the steering wheel 5. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor
Power steering that reduces steering force by the strike force
I do. [0002] 2. Description of the Related Art Conventionally, a driver is a steering wheel.
(Hereinafter referred to as the handle)
Steering torque is detected by a torque sensor, and this torque is
Assist torque corresponding to steering torque detected by sensor
Is generated by the electric motor in the steering direction of the steering wheel,
Reduce steering torque of driver to steer steering wheel
Electric power steering is known to facilitate this (dependent
Coming technology 1). On the other hand, for example, Japanese Patent Application Laid-Open No. 2000-108914
In the publication, the rotation axis of the steering wheel and the input shaft of the steering mechanism are
Disconnect the mechanical connection and use the driver's steering force or hand.
The steering angle of the steering wheel is converted into an electric signal, and based on this electric signal,
Technology to drive the steering mechanism (hereinafter referred to as steer-by-wire
(Referred to as prior art 2). Also examples
For example, Japanese Patent Application Laid-Open No. 2000-198452 discloses that
Sometimes, the steering angle of the wheel is larger than the steering angle of the steering wheel.
So that small turns are effective, and when driving at high speeds
Means that the steering angle of the wheel is smaller than the steering angle of the steering wheel
Gear ratio control for stable running
(Prior Art 3). Further, for example, Japanese Patent Application Laid-Open No. 2000-159134
Steering wheel, as disclosed in
Handles steering wheel speed to increase steering response
To change the actual steering angle, and the front wheels react sensitively to steering wheel steering
Front-wheel phase advance control is also known (for example,
Coming technology 4). [0005] The conventional electric motor
In power steering (Prior Art 1), turning the steering wheel
The turning shaft and the input shaft of the steering mechanism are mechanically firmly connected.
In addition, the assist torque corresponding to the steering torque is
Since it is generated by the motor,
Steering gear due to friction of the speed reduction mechanism
Ring is not good. Especially when a large motor is required
This effect is large in model cars and large cars, and electric power
-It is difficult to apply steering. Also, in this case,
Apply the above-mentioned variable gear ratio control and front wheel phase advance control
It is impossible. In the prior art 3, the variable gear ratio control is
Possible, but complicated in structure, and front wheel phase advance control
Can not be applied. Further, in the prior art 4,
Although variable gear ratio control and front wheel phase advance control are possible,
Is very complicated. On the other hand,
In No. 2, there is no mechanical connection between the steering wheel and the steering mechanism.
The electrical system connecting the steering wheel and the steering mechanism
If a system failure such as a failure occurs,
The steering mechanism is completely disconnected from the steering mechanism.
The power is not transmitted to the wheels even if the handle is operated.
It happens. Note that Japanese Patent Application Laid-Open No. 6-278625 discloses
Discloses the technology related to electric power steering
I have. And this technology is used for steer-by-wire system
By applying this function, even when the system fails,
The steering operation by the bus can be made possible. That is,
With this technology, the steering wheel is not
There is no mechanical connection between the steering mechanism and
When the steering angle exceeds the specified angle, the steering wheel
When the steering mechanism is connected,
Mechanical steering becomes possible. However, in this technique, the system
Operate the steering wheel to the specified steering angle when
Sharp mechanical connection between the steering wheel and the steering mechanism when
Occurs, so-called bottoming occurs and the steering load suddenly increases.
And the steering feel is not good.
is there. The present invention has been made in view of such problems.
Variable gear ratio control and phase advance control with a simple configuration.
Power steering system.
Steering without giving the driver a sense of incongruity during a fail
Providing power steering that enables operation
With the goal. [0009] According to the first aspect of the present invention, there is provided:
In the power steering of the present invention, the first steering angle detection
Means for detecting the steering angle of the steering wheel,
The actual steering angle of the wheel is detected by the second steering angle detecting means.
The actual steering angle detected by the second steering angle detecting means is equal to the first steering angle.
Target steering according to the steering angle detected by the steering angle detecting means
The steering mechanism is driven by the electric motor so that the angle
You. In addition, the shock absorbing member is provided on the steering wheel.
The steering wheel and the steering mechanism
The torsion member provided between the
Allow torsion within the enclosure. Therefore, up to a predetermined angle, the torsion member
Is steer-by-wire in this range
The steering system is the same as that of
Phase advance control becomes possible. Also, the steering device
Steering wheel at a specified angle
With the above operation, the torsion of the torsion member is no longer allowed.
Therefore, the steering mechanism according to the operation of the steering wheel
Is driven. Also, the steering amount of the steering wheel
Until the specified angle is reached,
The steering force of the steering wheel gradually increases
Therefore, a so-called bottom feeling does not occur. [0011] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment will be described. 1 to 5 show this embodiment.
FIG. 1 shows the configuration of the power steering.
FIG. 2 is a schematic perspective view, and FIG.
FIG. 3 is a lock diagram, and FIG.
FIG. 4 is a flowchart, and FIG.
FIG. 5 is a diagram showing an example of the control characteristics.
You. As shown in FIG. 1, one embodiment of the present invention
For vehicles to which power steering is applied,
The first steering angle sensor 1 and the second steering angle
Second steering angle sensor 2 as steering angle detecting means, torsion member
3.Rotary damper as shock absorbing member 4.Steary
Steering wheel (hereinafter referred to as steering wheel) 5, steering mechanism
6, electric motor 7, gain setting means 9, target steering angle setting
Means 10, a vehicle speed sensor 11, and the like. The first steering angle sensor 1 is, for example,
The rotation angle (steering angle) of the handle 5 is provided on the rotation shaft 5a.
θ_H1Is detected. Second steering angle sensor 2
Is provided on the input shaft 6a of the steering mechanism 6, for example,
Rotation angle of input shaft 6a of structure 6 (ie, actual operation of wheels (front wheels))
Steering angle) θ_H2Is detected. The twist member 3 is formed, for example, when twisting.
Is a torsion bar where the resistance is spring force.
5 and the steering mechanism 6 (specifically, the rotation axis of the steering wheel 5)
5a and the input shaft 6a of the steering mechanism 6).
I have. In addition, a torsion member (hereinafter referred to as a torsion bar)
3) Torsion around the rotation axis center within a range up to a predetermined angle
Is allowed. That is, the torsion bar 3
Is twisted more than a predetermined angle, the torsion bar 3 becomes rigid
It works. By the way, the steering wheel and the steering mechanism are
General power mechanically connected by the
In the steering mechanism, the torsion bar twist angle
Assist control according to the torsion bar screw
If the rigidity is low, the direct feeling of steering is impaired. This
Because of the common power steering torsion bar
Rigidity can be achieved as long as appropriate steering reaction force can be secured.
It is set large. For example, a general hydraulic power steering
The torsional rigidity of the torsion bar of the mechanism is about 17-22N
m / rad (about 0.03 to 0.04 kgf · m / de
g). Maximum operation that the driver generates during normal operation
The steering torque varies depending on the vehicle, but is approximately 3.0 Nm.
(About 0.3kgf ・ m), so in normal operation
The generated torsion bar twist angle is about 7.5-10d
eg (approximately 0.14 to 0.18 rad). On the other hand, in this embodiment, the torsion
Reduce the torsional rigidity of bar 3 and positively increase its torsional angle
Therefore, the torsional rigidity of the torsion bar 3 is
Torsion used for general power steering mechanism
5.6 Nm / rad of about 1/3 of the bar (about 0.01 kg
f / m / deg) and the torsion angle of about 30 deg
It is set to occur. That is, in this embodiment,
Torsion bar 3 allows ± 30 deg twist
Configured as a low rigidity torsion bar
You. The rotary damper 4 is a kind of shock absorbing damper.
And is connected to the handle 5 when the handle 5 is operated.
The steering reaction force is applied to the vehicle. In other words, Han
It is effective in response to the steering angular velocity of $ 5,
When the steering angular velocity of the steering wheel 5 is small, the resistance is small (immediately
The steering reaction force is small), and the steering angular velocity of the steering wheel 5 is large.
The resistance becomes large (that is, the steering reaction force becomes large) at high times
It is configured as follows. The rotary damper 4 allows the handle to be
Kickback and vibration from the road surface received by 5 are reduced
It has become. Further, the rotary damper 4 is
Of the shaft rotation direction generated when the torsion bar 3 returns
It also functions to reduce the force (torsion reaction force). What
By setting the characteristics of the rotary damper 4 as appropriate,
To change the magnitude of the steering reaction force of the rotary damper 4.
Both are possible. The steering mechanism 6 includes a pinion 8a and a rack shaft 8
b and a gear device 8
Front wheels 6b, 6b are connected to both ends of the shaft 8b. Electric
The dynamic motor 7 is connected to the steering mechanism 6 and has a second steering angle sensor
The actual steering angle of the front wheel detected at 2 is detected by the first steering angle sensor 1.
Target steering angle θ according to the issued steering angle_Two′
The steering mechanism 6 is driven. Here, the target steering angle θ_Two′ Is the ECU
Target steering angle setting hand provided in the slave control unit 12
It is set by step 10 and this
Variable gear ratio control and phase advance control are executed by the ECU 12.
It is supposed to be. The ECU 12 also stores the vehicle speed.
Gain K corresponding to vehicle speed V detected by sensor 11₁,
K_TwoIs set. Then, the target steering angle setting means 10
1 The steering angle θ of the steering wheel 5 detected by the steering angle sensor 1_H1When
Gain K set by gain setting means 9₁, K_TwoAnd from eyes
Target steering angle θ_Two′ Is set. here,
The front wheel phase advance control will be described. FIG. 2 and FIG.
As shown in FIG.
A proportional gain K based on the vehicle speed V detected by the₁Passing
And differential gain K_TwoIs set (step S shown in FIG. 3).
1). Note that the gain K₁, K_Two4A and FIG.
The characteristics are set as shown in FIG. Then, as shown in FIG.
The setting means 10 detects the hand detected by the first steering angle sensor 1.
Dollar 5 steering angle θ_H1And K set by the gain setting means 9
₁, K_TwoAnd the target steering angle θ_Two'Is set (Fig.
Step S2 shown in 3). Note that this target steering angle θ_Two′
Is obtained by the following equation. θ_Two'= K₁θ_H1+ K_Two(D
θ_H1/ Dt), that is, the target steering angle θ_Two′ Is the handle
Add an angle corresponding to the steering wheel steering speed to the steering angle.
And is required by: On the other hand, the actual steering of the wheels is performed by the second steering angle sensor 2.
Steering angle θ_H2Is detected, and the actual steering angle θ_H2But as above
Target steering angle θ set to_Two′ (Ie, the eye
Target steering angle θ_Two′ And the actual steering angle θ_H2So that the deviation from
2), so that the steering mechanism 6 is driven by the electric motor 7
(Step S3 shown in FIG. 3). like this
In the present embodiment, the rotating shaft 5a of the steering wheel 5 and the steering gear
Torsion with low torsional rigidity between input shaft 6a of structure 6
A bar 3 is provided to connect the rotation shaft 5a to the input shaft 6a.
Therefore, the predetermined angle at which torsion of the torsion bar 3 is allowed
Degrees based on information from the two steering angle sensors 1 and 2
It is a system similar to steer-by-wire that controls the steering angle.
And the steering angle θ detected by these two steering angle sensors 1 and 2.
_H1, Θ_H2And the vehicle speed V detected by the vehicle speed sensor 11
Thus, the front wheel phase advance control can be performed. In this embodiment, the variable gear ratio control is also performed.
It is possible. In this case, in the front wheel phase advance control described above,
The term corresponding to the steering wheel angular velocity may be set to 0.
That is, K_Two= 0. Hereinafter, referring to FIG.
Explaining the control characteristics of the variable gear ratio control,
Range in which the torsion bar 3 allows torsion (that is, −30).
deg to 30 deg). other than that
Twist angle (that is, -30 deg or less or 30 deg or less)
In (1), the torsion bar 3 is allowed to twist.
The steering mechanism 6 is directly driven. The variable gear ratio control is within the controllable range.
The center line (the line indicated by L in FIG. 5) is the variable gear ratio control.
The reference gear ratio, the pinion 8a of the gear device 8 and the rack
It is determined by the gear ratio with the shaft 8b. This embodiment
In this state, the inclination of the center line L is larger than the general gear ratio.
It is set large. In other words, general gear ratio control
Overall quicker control than
ing. When the vehicle is running at a high speed, the steering wheel
Steering angle θ_H1Front steering angle θ_H2Is the inclination of the center line L
And adjust to the general gear ratio inclination,
Steering angle θ_H1Front steering angle θ_H2Is relatively small
It is set to become. In other words, during high-speed driving
Make the front wheels more sensitive to steering
It is preventing it. On the other hand, when the vehicle is traveling at a low speed, the vehicle travels at a high speed.
Steering angle θ _H1Front wheel control
Steering angle θ_H2Is set to be large. That is,
Steering wheel steering is transmitted to front wheels sensitively at low speeds
In this way, agile driving can be performed. Toes
In low speed driving, quick (small gear ratio) characteristics,
Also, when running at high speed, a slow (large gear ratio) characteristic is obtained.
Variable gear ratio control allows the driver to
Reduced driving burden and stable driving at high speeds.
Wear. At the same time, in low-speed running,
The driver feels because the torsion of the bar 3 is small.
The reaction force is reduced, and the burden on the driver is reduced. Reverse
In high-speed running, the torsion bar 3 twists.
The reaction force felt by the driver is large because
Iba can feel a firm and heavy reaction force
You. The inclination of the controllable range depends on the vehicle type.
Can be changed as appropriate, the same inclination as the general gear ratio,
Alternatively, the inclination may be set smaller than the general gear ratio.
No. The power steering of the present invention is configured as described above.
If the steering system is normal,
The steering angle θ of the steering wheel 5 is determined by the first steering angle sensor 1._H1Is detected
The actual steering angle θ of the wheel is output by the second steering angle sensor 2._H2
Is detected. The gain setting means 9 controls the vehicle speed control.
Based on the vehicle speed V detected by the sensor 11, the gain K₁,
K_TwoIs set. Also, the target steering angle setting means 10
The gain K set by the gain setting means 9₁, K_TwoAnd ha
Steering angle θ of handle 5_H1Based on the target steering angle θ_Two′
Is set. Then, the electric motor 7 controls the second steering angle control.
Actual steering angle θ detected by sensor 2_H2Is the target steering angle θ_Two'When
Thus, the steering mechanism 6 is driven. Also like this
The front wheel phase advance control adjusts the steering wheel speed
The front wheels can be made to follow quickly. Also, the steering angle
Torque control for steering control using sensors 1 and 2.
Unlike power steering, which performs steering control
Steering discomfort due to motor inertia and friction is suppressed
It can be applied to medium and large vehicles. The torsion bar 3 is connected to the handle 5
Since it is provided between the steering mechanism 6 and the
Does not work due to ECU failure etc.
(Ie, when a system failure occurs)
Also, the steering wheel 5 and the steering mechanism 6 are connected via the torsion bar 3.
The steering force of the steering wheel 5
Can be transmitted to the steering mechanism 6, and the failsafe
Can be secured. In particular, the torsion bar 3 is
Tolerating ± 30 deg twist and -3
Does not allow twisting below 0 deg or above 30 deg
Therefore, at the time of a system failure, the handle 5 is
g or -30 deg or less, the steering wheel 5
The steering amount can be transmitted to the steering mechanism 6. Also,
± 30 deg screws due to the spring characteristics of the
Until the steering reaction is generated according to the amount of steering,
The driver can feel the steering reaction force,
When the twist of the member 3 becomes unacceptable (ie, the hand
When the steering angle of the steering wheel 5 is ± 30 deg), the driver
The front wheels 6b, 6b can be steered without feeling
Can be. As described above, the system failure
When the steering angle of the steering wheel 5 is ± 30 deg, the steering wheel
The driver does not steer because steering is not performed.
You can feel that something is wrong with the ring mechanism
You. Also, the steering angle of the steering wheel 5 is 30 deg or more or-
Steering by steering wheel is possible when it is less than 30 deg.
If the steering operation suddenly stops working while driving,
Emergency stop on the roadside and repair shops.
It is possible to run in. Further, for example, in steer-by-wire,
100% of the steering reaction force generated by the front wheels is
To generate steering reaction force
Power consumption is extremely high because
Although large, the power steering of the present invention
The steering angle of the driver when the rotation angle of the
Luk is transmitted to the front wheels via the torsion bar 3
And the larger the power consumed by steer-by-wire
Do not need. Further, the handle is provided by the rotary damper 4.
5 to reduce kickback and vibration from the road surface
Can be. In addition, the rotary damper 4
Force in the shaft rotation direction generated when the bar 3 returns torsion
(Torsion reaction force) to reduce the driver's natural steering reaction force
Can be given. That is, without the rotary damper 4
If the steering reaction transmitted to the driver is
3 only torsional reaction force, for example, during running or stationary
When the driver releases the handle 5 during
The handle 5 returned to neutral as if it had been flipped
This rotary damper 4
Avoid such a situation by being connected to 5
can do. Further, the torsion member 3 allows torsion.
The steering wheel is not transmitted to the front wheels within the specified range.
As with steer-by-wire, variable gear ratio control and front wheel position
Phase advance control can be performed. The embodiment of the present invention has been described above.
However, the present invention is limited to these embodiments.
It is not intended to deviate from the spirit of the present invention.
Modifications can be made. For example, in this embodiment, the front wheel phase advance control
Control and variable gear ratio control.
These controls may not be performed. FIG.
As shown in (a), rotation of the support 14 and the handle 5
A rigid plate 13 fixed to the shaft 5a, a support 14 and a rigid plate 13;
And the torsion member 3a
May be configured. Note that the support 14 is
The rotation shaft 5 is rotated so as to rotate integrally with the rotation shaft 5a of the handle 5.
a. Thus, the torsion bar of the present embodiment
3, the torsion of the rotating shaft 5a within a predetermined angle range.
Can be tolerated. Also, as in the present embodiment, the battery
The reaction force of the screw member 15 gives the driver a natural feeling of steering reaction.
And the screw of the torsion member 3a
Is no longer allowed (ie, the steering angle of the steering wheel 5 is
At a certain angle), the driver feels a bottom
The steering wheel 5 can be steered without any trouble. Further, as shown in FIG.
So that a rubber member 16 is provided in place of the screw member 15.
Is also good. Even in this case, the torsion bar
The same effect as when -3 is provided can be obtained. Also low
An electrically controlled damper instead of the tari damper 4 or
Using a motor, etc., these characteristics are controlled according to the driving conditions.
Control to further improve the steering feeling
You can also. [0042] As described in detail above, the book according to claim 1 is described.
According to the power steering of the invention, the steering device
When the system is normal, the torsion member allows torsion
Within a predetermined range, the amount of steering by the steering wheel
Variable as well as steer-by-wire because it is not transmitted to the wheel
Gear ratio control and front wheel phase advance control can be executed.
You. Further, the steering device is used in the system phase.
Even when the steering wheel is
And the steering mechanism are mechanically connected
The steering force of the wheel can be transmitted to the steering mechanism,
Fail safe can be secured. Also, at this time, twist
Steering force up to a predetermined angle of twist due to the spring characteristics of the member
Since a steering reaction force occurs in the opposite direction to the rotation direction of
The driver can feel the steering reaction force. In addition, the torsion of the torsion member is not allowed.
(Ie, the steering angle of the steering wheel has reached a predetermined angle)
At times), the driver hands
Steer. Therefore, the driver remembers discomfort
Never even. In addition, the shock absorbing member is
Force in the direction of shaft rotation that occurs when returning from torsion (torsion reaction force)
Driver feels more natural steering reaction
Can be

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically showing a configuration of a power steering as one embodiment of the present invention. FIG. 2 is a block diagram focusing on main functions of a power steering as one embodiment of the present invention. FIG. 3 is a flowchart for explaining phase advance control of power steering as one embodiment of the present invention. FIG. 4 is a map for setting a gain of phase advance control in power steering as one embodiment of the present invention. FIG. 5 is a diagram illustrating an example of a control characteristic of a power steering as one embodiment of the present invention. FIG. 6 is a schematic view showing a torsion member of a power steering as a modification of the present invention. [Description of Signs] 1 First steering angle sensor (first steering angle detecting means) 2 Second steering angle sensor (second steering angle detecting means) 3, 3a, 3b Torsion member 4 Rotary damper (impact relief member) Reference Signs List 5 steering wheel (steering wheel) 5a handle rotating shaft 6 steering mechanism 6a steering mechanism input shaft 6b front wheel 7 electric motor 8 gear device 8a pinion 8b rack shaft 9 gain setting means 10 target steering angle setting means 11 vehicle speed sensor 12 ECU (electronic) Control unit) 13 Rigid plate 14 Support 15 Spring member 16 Rubber member

Claims (1)

Claims: 1. A first steering angle detecting means for detecting a steering angle of a steering wheel, a second steering angle detecting means for detecting an actual steering angle of a wheel, and a second steering angle. An electric motor for driving a steering mechanism such that an actual steering angle detected by the detection means becomes a target steering angle corresponding to the steering angle detected by the first steering angle detection means. A power steering device comprising: a torsion member provided between the steering wheel and the steering mechanism; and a torsion member that allows torsion within a range of up to a predetermined angle, and an impact absorbing member connected to the steering wheel.