JP2004224077A - Electric power steering device - Google Patents

Electric power steering device Download PDF

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Publication number
JP2004224077A
JP2004224077A JP2003010983A JP2003010983A JP2004224077A JP 2004224077 A JP2004224077 A JP 2004224077A JP 2003010983 A JP2003010983 A JP 2003010983A JP 2003010983 A JP2003010983 A JP 2003010983A JP 2004224077 A JP2004224077 A JP 2004224077A
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Japan
Prior art keywords
steering
torque
rotation angle
abnormality
electric motor
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JP2003010983A
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JP4007200B2 (en
Inventor
Koji Kanda
耕治 神田
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Koyo Seiko Co Ltd
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Koyo Seiko Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device for preventing the abrupt change of steering torque when an abnormality occurs in a torque sensor. <P>SOLUTION: The electric power steering device comprises a torque sensor of two systems for detecting steering torque applied to a steering shaft including a joint member for joining an input shaft and an output shaft joined to a steering mechanism, an electric motor driven based on the detected steering torque, a decelerating mechanism for decelerating the rotation of the electric motor and transmitting it to the output shaft, and an abnormality detecting means of the torque sensor. When the abnormality detecting means detects the abnormality (S8), steering torque is calculated based on a steering wheel rotation angle, a motor rotation angle, a spring constant of the joint member, and a deceleration ratio of the decelerating mechanism (S10), it is determined which steering torque detected by the torque sensor of two systems is close to the calculated steering torque (S12), and the electric motor is driven (S16 and S18) based on the steering torque detected by the torque sensor that is determined to be closer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、操舵軸に加わる操舵トルクを検出するトルクセンサを２系統備え、２系統のトルクセンサが検出した操舵トルクに基づき電動モータを駆動し、その駆動力により操舵補助を行なう電動パワーステアリング装置に関するものである。
【０００２】
【従来の技術】
車両に装備される電動パワーステアリング装置は、車両の操舵力を電動モータにより補助するものであり、これは、操舵部材（操舵輪）と操舵軸とが連結された舵取機構に、操舵部材に加えられた操舵トルクを検出するトルクセンサと、舵取機構の動作を補助する操舵補助用の電動モータとを設け、トルクセンサが検出した操舵トルクに応じた操舵補助力を得られるように、電動モータを駆動させることにより、操舵部材への操作力を軽減するように構成してある。また、車両の高速走行時に、操舵部材への操作力が軽くなり過ぎないように、車速に応じた操舵補助力を得られるようになっている。
【０００３】
【特許文献１】
特公平６−９９７３号公報
【０００４】
【発明が解決しようとする課題】
上述したような従来の電動パワーステアリング装置では、トルクセンサを２系統設けておき、両系統の検出値が異なる値を示したとき、トルクセンサが異常であると判定しているが、何れの検出値が正しいかは判定出来ない為、異常であると判定したときは、操舵補助を停止している。その為、トルクセンサに異常が発生したときは、急にハンドルが重くなるという問題があった。
特許文献１には、トルクセンサの第１及び第２の変位対電気信号の偏差が所定値以上になると、コントロールユニットが異常と判定して、モータの電流と電磁クラッチの印加電圧とを遮断するモータ駆動式パワーステアリング制御装置が開示されている。
【０００５】
本発明は、上述したような事情に鑑みてなされたものであり、トルクセンサに異常が発生したときに、操舵トルクが急変することがない電動パワーステアリング装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
第１発明に係る電動パワーステアリング装置は、操舵部材に連結された入力軸と舵取機構に連結された出力軸とを連結する連結部材を含む操舵軸と、該操舵軸に加わる操舵トルクを検出する２系統のトルクセンサと、該２系統のトルクセンサが検出した操舵トルクに基づき駆動される電動モータと、該電動モータの回転を減速して前記出力軸に伝える減速機構と、前記トルクセンサの異常を検出する異常検出手段とを備える電動パワーステアリング装置において、前記操舵輪の回転角を検出する操舵輪回転角検出手段と、前記電動モータの回転角を検出するモータ回転角検出手段と、前記異常検出手段が異常を検出したときに、前記操舵輪回転角検出手段が検出した回転角、前記モータ回転角検出手段が検出した回転角、前記連結部材のばね定数及び前記減速機構の減速比に基づき操舵トルクを算出する算出手段と、該算出手段が算出した操舵トルクが前記２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定する判定手段とを備え、前記異常検出手段が異常を検出した以後は、前記判定手段が近いと判定した方のトルクセンサが検出した操舵トルクに基づき、前記電動モータを駆動すべくなしてあることを特徴とする。
【０００７】
この電動パワーステアリング装置では、異常検出手段がトルクセンサの異常を検出したときに、操舵部材の回転角、電動モータの回転角、連結部材のばね定数及び減速機構の減速比に基づき操舵トルクを算出し、その算出した操舵トルクが２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定して、トルクセンサの異常を検出した以後は、近いと判定した方のトルクセンサが検出した操舵トルクに基づき、電動モータを駆動する。
これにより、トルクセンサに異常が発生したときに、操舵トルクが急変することがない電動パワーステアリング装置を実現することが出来る。
【０００８】
第２発明に係る電動パワーステアリング装置は、操舵部材に連結された入力軸と舵取機構に連結された出力軸とを連結する連結部材を含む操舵軸と、該操舵軸に加わる操舵トルクを検出する２系統のトルクセンサと、該２系統のトルクセンサが検出した操舵トルクに基づき駆動される電動モータと、該電動モータの回転を減速して前記出力軸に伝える減速機構と、前記トルクセンサの異常を検出する異常検出手段とを備える電動パワーステアリング装置において、前記操舵輪の回転角を検出する操舵輪回転角検出手段と、前記電動モータの回転角を検出するモータ回転角検出手段と、前記異常検出手段が異常を検出したときに、前記操舵輪回転角検出手段が検出した回転角、前記モータ回転角検出手段が検出した回転角、前記連結部材のばね定数及び前記減速機構の減速比に基づき操舵トルクを算出する算出手段と、該算出手段が算出した操舵トルクが前記２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定する判定手段とを備え、前記異常検出手段が異常を検出した以後は、前記判定手段が近いと判定した方のトルクセンサが検出した操舵トルクに基づき、前記電動モータを駆動しながら、該電動モータの駆動力を漸減させ、停止すべくなしてあることを特徴とする。
【０００９】
この電動パワーステアリング装置では、異常検出手段がトルクセンサの異常を検出したときに、操舵部材の回転角、電動モータの回転角、連結部材のばね定数及び減速機構の減速比に基づき操舵トルクを算出し、その算出した操舵トルクが２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定して、トルクセンサの異常を検出した以後は、近いと判定した方のトルクセンサが検出した操舵トルクに基づき、電動モータを駆動しながら、その駆動力を漸減させて停止する。
これにより、トルクセンサに異常が発生したときに、操舵トルクを急変させることなく停止する電動パワーステアリング装置を実現することが出来る。
【００１０】
【発明の実施の形態】
以下に、本発明をその実施の形態を示す図面に基づき説明する。
実施の形態１．
図１は、本発明に係る電動パワーステアリング装置の実施の形態の構成を示す模式図であり、図２は、この電動パワーステアリング装置の実施の形態の構成を示す縦断面図である。この電動パワーステアリング装置は、例えば舵取りの為の操舵輪７（操舵部材）と、操舵輪７の操舵に応じて駆動される操舵補助用の電動モータ１と、電動モータ１の回転を減速歯車機構２を介して舵取機構３，３に伝える伝動手段４と、電動モータ１の駆動回路５を制御する制御部６とを備えている。
【００１１】
操舵輪７には、その回転角を検出する操舵輪回転角センサ１７（操舵輪回転角検出手段）が設けられ、操舵輪回転角センサ１７が検出した回転角は制御部６に与えられる。
電動モータ１には、その回転角を検出するレゾルバ等のモータ回転角センサ１８（モータ回転角検出手段）が設けられ、モータ回転角センサ１８が検出した回転角は制御部６に与えられる。
【００１２】
操舵輪７は、入力軸１６に連結されている。
伝動手段４は、入力軸１６にトーションバー８（連結部材）を介して連結される出力軸９と、出力軸９にユニバーサルジョイント等の連結軸１０を介して連結されるピニオン軸１１と、ピニオン軸１１のピニオンに噛合するラック歯を有し、左右の操向輪Ａ，Ａに舵取機構３，３を介して連結されるラック軸１２とを備えている。入力軸１６及び伝動手段４は操舵軸１９を構成している。
【００１３】
入力軸１６の周りには、操舵輪７を操作することにより入力軸１６に加わる操舵トルクを、トーションバー８に生じる捩れによって検出する２系統からなるトルクセンサ１３が配置されており、２系統からなるトルクセンサ１３がそれぞれ検出した操舵トルクに基づいて、制御部６が駆動回路５を制御するように構成してある。
減速歯車機構２（減速機構）は、電動モータ１の出力軸に繋がるウォーム１４と、出力軸９の途中に嵌合されるウォームホイール１５とを備えており、電動モータ１の回転をウォーム１４及ウォームホイール１５から出力軸９に伝達するように構成してある。
【００１４】
このような構成の電動パワーステアリング装置では、操舵輪７の操作による舵取り操作力を入力軸１６、トーションバー８、出力軸９、連結軸１０、及びピニオン軸１１を介してラック軸１２に伝達し、ラック軸１２を軸長方向へ移動させ、舵取機構３，３を作動させる。また、それと共に、トルクセンサ１３が検出した操舵トルクに基づき、制御部６が駆動回路５を制御して電動モータ１を駆動し、電動モータ１の駆動力を出力軸９に伝達することにより、舵取り操作力を補助し、舵取りのための運転者の労力負担を軽減する。
【００１５】
以下に、この電動パワーステアリング装置のトルクセンサの異常を検出するときの動作を、それを示す図３のフローチャートを参照しながら説明する。
制御部６は、先ず、フラグＦ１が１であるか否かを判定し（Ｓ２）、１でなければ、フラグＦ２が１であるか否かを判定する（Ｓ４）。
制御部６は、フラグＦ２が１でなければ（Ｓ４）、２系統あるトルクセンサ１３がそれぞれ検出した操舵トルク信号Ｔ１，Ｔ２を読み込み（Ｓ６）、操舵トルク信号Ｔ１，Ｔ２の差の絶対値が所定値以上であるか否かを判定する（Ｓ８）。尚、フラグＦ１，Ｆ２は、電動パワーステアリング装置の起動時に初期設定され、０になっているものとする。
【００１６】
制御部６は、操舵トルク信号Ｔ１，Ｔ２の差の絶対値が所定値以上であれば（Ｓ８）、操舵輪回転角センサ１７が検出した回転角Ａ１、モータ回転角センサ１８が検出した回転角Ａ２、トーションバーのばね定数Ｋ及び減速歯車機構２の減速比Ｎに基づき、次式により操舵トルク値Ｔｃａｌを算出する（Ｓ１０）。
Ｔｃａｌ＝Ｋ×（Ａ１−（Ａ２／Ｎ））
【００１７】
制御部６は、次に、操舵トルク信号Ｔ１，Ｔ２と算出した操舵トルク値Ｔｃａｌとの各差の絶対値の何れが大きいかを判定し（Ｓ１２）、操舵トルク信号Ｔ１と操舵トルク値Ｔｃａｌとの差の方が大きければ、フラグＦ２を１とする（Ｓ１４、フラグＦ２を立てる）。次いで、操舵トルク信号Ｔ２に基づき、電動モータ１を駆動しながら、その駆動力を漸減させて（Ｓ１６）リターンし、徐々に操舵補助を停止する。
制御部６は、操舵トルク信号Ｔ２と操舵トルク値Ｔｃａｌとの差の方が大きければ（Ｓ１２）、フラグＦ１を１として（Ｓ１８、フラグＦ１を立て）、操舵トルク信号Ｔ１に基づき、電動モータ１を駆動しながら、その駆動力を漸減させて（Ｓ２０）リターンし、徐々に操舵補助を停止する。
【００１８】
制御部６は、フラグＦ１が１であれば（Ｓ２）、操舵トルク信号Ｔ１に基づき、電動モータ１を駆動しながら、その駆動力を漸減させて（Ｓ２０）リターンし、徐々に操舵補助を停止する。
制御部６は、フラグＦ２が１であれば（Ｓ４）、操舵トルク信号Ｔ２に基づき、電動モータ１を駆動しながら、その駆動力を漸減させて（Ｓ１６）リターンし、徐々に操舵補助を停止する。
【００１９】
制御部６は、操舵トルク信号Ｔ１，Ｔ２の差の絶対値が所定値以上でなければ（Ｓ８）リターンし、通常の操舵補助を行なう。
尚、この実施の形態では、トルクセンサ１３の異常時に、算出した操舵トルク値Ｔｃａｌに近かった方の操舵トルク信号に基づき、電動モータ１を駆動しながら、その駆動力を漸減させ、徐々に操舵補助を停止しているが、その駆動力を漸減させずに、操舵補助を続行するようにしても良い。
【００２０】
【発明の効果】
第１発明に係る電動パワーステアリング装置によれば、トルクセンサに異常が発生したときに、操舵トルクが急変することがない電動パワーステアリング装置を実現することが出来る。
【００２１】
第２発明に係る電動パワーステアリング装置によれば、トルクセンサに異常が発生したときに、操舵トルクを急変させることなく停止する電動パワーステアリング装置を実現することが出来る。
【図面の簡単な説明】
【図１】本発明に係る電動パワーステアリング装置の実施の形態の構成を示す模式図である。
【図２】本発明に係る電動パワーステアリング装置の実施の形態の構成を示す縦断面図である。
【図３】本発明に係る電動パワーステアリング装置の実施の形態の動作を示すフローチャートである。
【符号の説明】
１ 電動モータ
２ 減速歯車機構（減速機構）
３ 舵取機構
６ 制御部（異常検出手段、算出手段、判定手段）
７ 操舵輪（操舵部材）
８ トーションバー（連結部材）
９ 出力軸
１３ トルクセンサ
１６ 入力軸
１７ 操舵輪回転角センサ（操舵輪回転角検出手段）
１８ モータ回転角センサ（モータ回転角検出手段）
１９ 操舵軸[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric power steering apparatus including two systems of torque sensors for detecting a steering torque applied to a steering shaft, driving an electric motor based on the steering torque detected by the two systems of torque sensors, and assisting the steering with the driving force. It is about.
[0002]
[Prior art]
BACKGROUND ART An electric power steering device mounted on a vehicle assists a steering force of the vehicle with an electric motor. The electric power steering device includes a steering mechanism in which a steering member (steering wheel) and a steering shaft are connected to each other, and a steering member in which a steering member is connected. A torque sensor for detecting the applied steering torque and an electric motor for steering assist for assisting the operation of the steering mechanism are provided, and an electric motor is provided so as to obtain a steering assist force corresponding to the steering torque detected by the torque sensor. By driving the motor, the operation force on the steering member is reduced. Further, when the vehicle is running at high speed, a steering assist force according to the vehicle speed can be obtained so that the operation force on the steering member does not become too light.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 6-9973
[Problems to be solved by the invention]
In the conventional electric power steering apparatus as described above, two torque sensors are provided, and when the detected values of the two systems indicate different values, it is determined that the torque sensor is abnormal. Since it cannot be determined whether the value is correct, when it is determined that the value is abnormal, the steering assist is stopped. Therefore, there is a problem that when an abnormality occurs in the torque sensor, the steering wheel suddenly becomes heavy.
Patent Document 1 discloses that when the deviation between the first and second displacements of the torque sensor and the electric signal becomes equal to or more than a predetermined value, the control unit determines that the control unit is abnormal, and cuts off the motor current and the voltage applied to the electromagnetic clutch. A motor-driven power steering control device is disclosed.
[0005]
The present invention has been made in view of the above-described circumstances, and has as its object to provide an electric power steering device in which the steering torque does not suddenly change when an abnormality occurs in the torque sensor.
[0006]
[Means for Solving the Problems]
An electric power steering apparatus according to a first aspect of the present invention detects a steering shaft including a connecting member that connects an input shaft connected to a steering member and an output shaft connected to a steering mechanism, and detects a steering torque applied to the steering shaft. A two-system torque sensor, an electric motor driven based on steering torque detected by the two-system torque sensor, a reduction mechanism for reducing the rotation of the electric motor and transmitting the rotation to the output shaft, An electric power steering apparatus including abnormality detection means for detecting abnormality, a steering wheel rotation angle detection means for detecting a rotation angle of the steering wheel, a motor rotation angle detection means for detecting a rotation angle of the electric motor, A rotation angle detected by the steering wheel rotation angle detection means, a rotation angle detected by the motor rotation angle detection means, and a spring of the connecting member when the abnormality detection means detects an abnormality. Calculating means for calculating the steering torque based on the number and the reduction ratio of the speed reduction mechanism, and determining means for determining which of the steering torques detected by the two-system torque sensor is closer to the steering torque calculated by the calculating means. After the abnormality detecting means detects the abnormality, the electric motor is driven based on the steering torque detected by the torque sensor which is determined to be close by the determining means.
[0007]
In this electric power steering apparatus, when the abnormality detecting unit detects abnormality of the torque sensor, the steering torque is calculated based on the rotation angle of the steering member, the rotation angle of the electric motor, the spring constant of the connecting member, and the reduction ratio of the reduction mechanism. Then, it is determined whether the calculated steering torque is closer to the steering torque detected by the two-system torque sensor, and after the abnormality of the torque sensor is detected, the steering torque detected by the torque sensor determined to be closer is detected. The electric motor is driven based on.
Thus, it is possible to realize an electric power steering device in which the steering torque does not suddenly change when an abnormality occurs in the torque sensor.
[0008]
An electric power steering apparatus according to a second aspect of the invention detects a steering shaft including a connecting member that connects an input shaft connected to a steering member and an output shaft connected to a steering mechanism, and detects a steering torque applied to the steering shaft. A two-system torque sensor, an electric motor driven based on steering torque detected by the two-system torque sensor, a reduction mechanism for reducing the rotation of the electric motor and transmitting the rotation to the output shaft, An electric power steering apparatus including abnormality detection means for detecting abnormality, a steering wheel rotation angle detection means for detecting a rotation angle of the steering wheel, a motor rotation angle detection means for detecting a rotation angle of the electric motor, A rotation angle detected by the steering wheel rotation angle detection means, a rotation angle detected by the motor rotation angle detection means, and a spring of the connecting member when the abnormality detection means detects an abnormality. Calculating means for calculating the steering torque based on the number and the reduction ratio of the speed reduction mechanism, and determining means for determining which of the steering torques detected by the two-system torque sensor is closer to the steering torque calculated by the calculating means. After the abnormality detecting means detects an abnormality, the driving force of the electric motor is gradually reduced while driving the electric motor based on the steering torque detected by the torque sensor determined to be close by the determining means. And stopped.
[0009]
In this electric power steering apparatus, when the abnormality detecting unit detects abnormality of the torque sensor, the steering torque is calculated based on the rotation angle of the steering member, the rotation angle of the electric motor, the spring constant of the connecting member, and the reduction ratio of the reduction mechanism. Then, it is determined whether the calculated steering torque is closer to the steering torque detected by the two-system torque sensor, and after the abnormality of the torque sensor is detected, the steering torque detected by the torque sensor determined to be closer is detected. Based on the above, while driving the electric motor, the driving force is gradually reduced and stopped.
Thus, it is possible to realize an electric power steering device that stops without suddenly changing the steering torque when an abnormality occurs in the torque sensor.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments.
Embodiment 1 FIG.
FIG. 1 is a schematic diagram illustrating a configuration of an embodiment of an electric power steering device according to the present invention, and FIG. 2 is a longitudinal sectional view illustrating a configuration of the embodiment of the electric power steering device. This electric power steering device includes, for example, a steered wheel 7 (steering member) for steering, an electric motor 1 for steering assistance driven in accordance with the steering of the steered wheel 7, and a reduction gear mechanism for rotating the electric motor 1. And a control unit 6 for controlling a driving circuit 5 of the electric motor 1.
[0011]
The steering wheel 7 is provided with a steering wheel rotation angle sensor 17 (steering wheel rotation angle detecting means) for detecting the rotation angle, and the rotation angle detected by the steering wheel rotation angle sensor 17 is given to the control unit 6.
The electric motor 1 is provided with a motor rotation angle sensor 18 (motor rotation angle detection means) such as a resolver for detecting the rotation angle, and the rotation angle detected by the motor rotation angle sensor 18 is given to the control unit 6.
[0012]
The steered wheels 7 are connected to an input shaft 16.
The transmission means 4 includes: an output shaft 9 connected to the input shaft 16 via a torsion bar 8 (connection member); a pinion shaft 11 connected to the output shaft 9 via a connection shaft 10 such as a universal joint; A rack shaft 12 having rack teeth meshing with the pinion of the shaft 11 and being connected to left and right steered wheels A, A via steering mechanisms 3 and 3 is provided. The input shaft 16 and the transmission means 4 constitute a steering shaft 19.
[0013]
Around the input shaft 16, a two-system torque sensor 13 that detects a steering torque applied to the input shaft 16 by operating the steered wheels 7 by a torsion generated in the torsion bar 8 is arranged. The controller 6 controls the drive circuit 5 based on the steering torque detected by each of the torque sensors 13.
The reduction gear mechanism 2 (reduction mechanism) includes a worm 14 that is connected to the output shaft of the electric motor 1 and a worm wheel 15 that is fitted in the middle of the output shaft 9. The transmission is transmitted from the worm wheel 15 to the output shaft 9.
[0014]
In the electric power steering apparatus having such a configuration, the steering operation force by operating the steered wheels 7 is transmitted to the rack shaft 12 via the input shaft 16, the torsion bar 8, the output shaft 9, the connecting shaft 10, and the pinion shaft 11. Then, the rack shaft 12 is moved in the axial direction, and the steering mechanisms 3 and 3 are operated. At the same time, based on the steering torque detected by the torque sensor 13, the control unit 6 controls the drive circuit 5 to drive the electric motor 1 and transmit the driving force of the electric motor 1 to the output shaft 9, The steering operation force is assisted, and the driver's labor burden for steering is reduced.
[0015]
The operation of the electric power steering device when detecting an abnormality in the torque sensor will be described below with reference to the flowchart of FIG.
The control unit 6 first determines whether or not the flag F1 is 1 (S2), and if not, determines whether or not the flag F2 is 1 (S4).
If the flag F2 is not 1 (S4), the control unit 6 reads the steering torque signals T1 and T2 detected by the two-system torque sensors 13 (S6), and the absolute value of the difference between the steering torque signals T1 and T2 is determined. It is determined whether or not it is equal to or more than a predetermined value (S8). The flags F1 and F2 are initially set when the electric power steering apparatus is started, and are assumed to be 0.
[0016]
When the absolute value of the difference between the steering torque signals T1 and T2 is equal to or greater than a predetermined value (S8), the control unit 6 determines the rotation angle A1 detected by the steering wheel rotation angle sensor 17 and the rotation angle detected by the motor rotation angle sensor 18. Based on A2, the spring constant K of the torsion bar, and the reduction ratio N of the reduction gear mechanism 2, a steering torque value Tcal is calculated by the following equation (S10).
Tcal = K × (A1- (A2 / N))
[0017]
Next, the control unit 6 determines which of the absolute values of the differences between the steering torque signals T1 and T2 and the calculated steering torque value Tcal is greater (S12), and determines the steering torque signal T1 and the steering torque value Tcal. If the difference is larger, the flag F2 is set to 1 (S14, the flag F2 is set). Next, based on the steering torque signal T2, while driving the electric motor 1, the driving force is gradually reduced (S16), and the process returns to gradually stop the steering assist.
If the difference between the steering torque signal T2 and the steering torque value Tcal is larger (S12), the controller 6 sets the flag F1 to 1 (S18, sets the flag F1), and based on the steering torque signal T1, sets the electric motor 1 , The driving force is gradually reduced (S20), and the process returns to gradually stop the steering assist.
[0018]
When the flag F1 is 1 (S2), the control unit 6 gradually reduces the driving force while driving the electric motor 1 based on the steering torque signal T1 (S20), and returns to stop the steering assist gradually. I do.
If the flag F2 is 1 (S4), the control unit 6 gradually reduces the driving force while driving the electric motor 1 based on the steering torque signal T2 (S16), and returns to stop the steering assist gradually. I do.
[0019]
If the absolute value of the difference between the steering torque signals T1 and T2 is not equal to or greater than the predetermined value (S8), the control unit 6 returns and performs normal steering assistance.
In this embodiment, when the torque sensor 13 is abnormal, the driving force of the electric motor 1 is gradually reduced while driving the electric motor 1 based on the steering torque signal closer to the calculated steering torque value Tcal, and the steering is gradually performed. Although the assist is stopped, the steering assist may be continued without gradually reducing the driving force.
[0020]
【The invention's effect】
According to the electric power steering device according to the first invention, it is possible to realize an electric power steering device in which the steering torque does not suddenly change when an abnormality occurs in the torque sensor.
[0021]
According to the electric power steering device according to the second aspect of the invention, it is possible to realize an electric power steering device that stops without suddenly changing the steering torque when an abnormality occurs in the torque sensor.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an embodiment of an electric power steering device according to the present invention.
FIG. 2 is a longitudinal sectional view showing a configuration of an embodiment of an electric power steering device according to the present invention.
FIG. 3 is a flowchart showing an operation of the embodiment of the electric power steering device according to the present invention.
[Explanation of symbols]
1 electric motor 2 reduction gear mechanism (reduction mechanism)
3 steering mechanism 6 control unit (abnormality detection means, calculation means, determination means)
7 Steering wheel (steering member)
8 Torsion bar (connecting member)
9 Output shaft 13 Torque sensor 16 Input shaft 17 Steering wheel rotation angle sensor (steering wheel rotation angle detecting means)
18 Motor rotation angle sensor (motor rotation angle detection means)
19 Steering axis

Claims (2)

操舵部材に連結された入力軸と舵取機構に連結された出力軸とを連結する連結部材を含む操舵軸と、該操舵軸に加わる操舵トルクを検出する２系統のトルクセンサと、該２系統のトルクセンサが検出した操舵トルクに基づき駆動される電動モータと、該電動モータの回転を減速して前記出力軸に伝える減速機構と、前記トルクセンサの異常を検出する異常検出手段とを備える電動パワーステアリング装置において、
前記操舵輪の回転角を検出する操舵輪回転角検出手段と、前記電動モータの回転角を検出するモータ回転角検出手段と、前記異常検出手段が異常を検出したときに、前記操舵輪回転角検出手段が検出した回転角、前記モータ回転角検出手段が検出した回転角、前記連結部材のばね定数及び前記減速機構の減速比に基づき操舵トルクを算出する算出手段と、該算出手段が算出した操舵トルクが前記２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定する判定手段とを備え、前記異常検出手段が異常を検出した以後は、前記判定手段が近いと判定した方のトルクセンサが検出した操舵トルクに基づき、前記電動モータを駆動すべくなしてあることを特徴とする電動パワーステアリング装置。A steering shaft including a connecting member that connects an input shaft connected to a steering member and an output shaft connected to a steering mechanism; two systems of torque sensors for detecting a steering torque applied to the steering shaft; An electric motor that is driven based on the steering torque detected by the torque sensor, a reduction mechanism that reduces the rotation of the electric motor to transmit the rotation to the output shaft, and abnormality detection means that detects abnormality of the torque sensor. In power steering devices,
Steering wheel rotation angle detection means for detecting the rotation angle of the steering wheel; motor rotation angle detection means for detecting the rotation angle of the electric motor; and the steering wheel rotation angle when the abnormality detection means detects an abnormality. Calculating means for calculating a steering torque based on the rotation angle detected by the detection means, the rotation angle detected by the motor rotation angle detection means, the spring constant of the connecting member, and the reduction ratio of the speed reduction mechanism; Determining means for determining which of the steering torques the steering torque is closer to the steering torque detected by the two-system torque sensor, and after the abnormality detecting means detects an abnormality, the torque determined by the determining means to be closer An electric power steering apparatus, wherein the electric motor is driven based on a steering torque detected by a sensor. 操舵部材に連結された入力軸と舵取機構に連結された出力軸とを連結する連結部材を含む操舵軸と、該操舵軸に加わる操舵トルクを検出する２系統のトルクセンサと、該２系統のトルクセンサが検出した操舵トルクに基づき駆動される電動モータと、該電動モータの回転を減速して前記出力軸に伝える減速機構と、前記トルクセンサの異常を検出する異常検出手段とを備える電動パワーステアリング装置において、
前記操舵輪の回転角を検出する操舵輪回転角検出手段と、前記電動モータの回転角を検出するモータ回転角検出手段と、前記異常検出手段が異常を検出したときに、前記操舵輪回転角検出手段が検出した回転角、前記モータ回転角検出手段が検出した回転角、前記連結部材のばね定数及び前記減速機構の減速比に基づき操舵トルクを算出する算出手段と、該算出手段が算出した操舵トルクが前記２系統のトルクサンサが検出した操舵トルクの何れに近いかを判定する判定手段とを備え、前記異常検出手段が異常を検出した以後は、前記判定手段が近いと判定した方のトルクセンサが検出した操舵トルクに基づき、前記電動モータを駆動しながら、該電動モータの駆動力を漸減させ、停止すべくなしてあることを特徴とする電動パワーステアリング装置。A steering shaft including a connecting member that connects an input shaft connected to a steering member and an output shaft connected to a steering mechanism; two systems of torque sensors for detecting a steering torque applied to the steering shaft; An electric motor that is driven based on the steering torque detected by the torque sensor, a reduction mechanism that reduces the rotation of the electric motor to transmit the rotation to the output shaft, and abnormality detection means that detects abnormality of the torque sensor. In power steering devices,
Steering wheel rotation angle detection means for detecting the rotation angle of the steering wheel; motor rotation angle detection means for detecting the rotation angle of the electric motor; and the steering wheel rotation angle when the abnormality detection means detects an abnormality. Calculating means for calculating a steering torque based on the rotation angle detected by the detection means, the rotation angle detected by the motor rotation angle detection means, the spring constant of the connecting member, and the reduction ratio of the speed reduction mechanism; Determining means for determining which of the steering torques the steering torque is closer to the steering torque detected by the two-system torque sensor, and after the abnormality detecting means detects an abnormality, the torque determined by the determining means to be closer An electric power steering system for driving the electric motor based on a steering torque detected by a sensor while gradually reducing a driving force of the electric motor and stopping the electric motor. Grayed apparatus.
JP2003010983A 2003-01-20 2003-01-20 Electric power steering device Expired - Fee Related JP4007200B2 (en)

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