JP2009067222A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of determining any abnormality of a torque sensor system based on a plurality of detected torque signals from one torque sensor, expanding the effective range of the assist by segmentalizing and detecting an abnormality generating part, and performing the efficient assist control. <P>SOLUTION: In the electric power steering device, a motor for providing the assist torque to a steering system is drive-controlled by the current command value computed based on a plurality of torque signals from a torque sensor and the vehicle speed. The electric power steering device comprises an abnormality diagnosis unit which is changed by diagnosing abnormality of the plurality of torque signals, a diagnosis supporting unit for diagnosing abnormality of the plurality of torque signals, and a diagnosis and determination control unit for changing the output torque signal by determining the abnormality of a torque sensor system based on the results of diagnosis of the abnormality diagnosis unit and the diagnosis supporting unit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus in which a steering assist force by a motor is applied to a steering system of a vehicle, and more particularly, to an electric power steering apparatus that detects an abnormality of a torque sensor system and efficiently controls it.

  An electric power steering device for energizing a vehicle steering device with an auxiliary load by the rotational force of a motor energizes an auxiliary load to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a reduction gear. It is supposed to be. Such a conventional electric power steering apparatus performs feedback control of motor current in order to accurately generate assist torque (steering assist force). In the feedback control, the motor applied voltage is adjusted so that the difference between the current command value and the motor current detection value becomes small. Generally, the adjustment of the motor applied voltage is a duty of PWM (pulse width modulation) control. This is done by adjusting the tee ratio.

  Here, the general configuration of the electric power steering apparatus will be described with reference to FIG. It is connected to. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the handle 1, and a motor 20 that assists the steering force of the handle 1 is connected to the column shaft 2 via the reduction gear 3. A power is supplied from the battery 14 to the control unit 30 that controls the power steering device, and an ignition signal is input through the ignition key 11. The control unit 30 detects the steering torque Th detected by the torque sensor 10 and the vehicle speed. An assist command steering assist command value I is calculated based on the vehicle speed V detected by the sensor 12, and a current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

  The control unit 30 is mainly composed of a CPU (including an MPU and MCU). FIG. 5 shows general functions executed by a program in the CPU.

  The function and operation of the control unit 30 will be described with reference to FIG. 5. The steering torque Th detected by the torque sensor 10 is input to the steering assist command value calculation unit 32, and the vehicle speed V detected by the vehicle speed sensor 12 is also steered. This is input to the auxiliary command value calculation unit 32. The steering assist command value calculation unit 32 refers to the assist map stored in the memory 33 based on the input steering torque Th and the vehicle speed V, and the steering assist command is a control target value of the current supplied to the motor 20. Determine the value I. The steering assist command value I is input to the subtraction unit 30A and is also input to the feedforward differential compensation unit 34 for increasing the response speed, and the deviation (Ii) of the subtraction unit 30A is input to the proportional calculation unit 35. At the same time, it is input to the integral calculation unit 36 for improving the characteristics of the feedback system, and its proportional output is input to the addition unit 30B. The outputs of the differential compensator 34 and the integral compensator 36 are also added to the adder 30B, and the current control value E, which is the addition result of the adder 30B, is input to the motor drive circuit 37 as a motor drive signal. Electric power is supplied from the battery 14 to the motor drive circuit 37, the motor current value i of the motor 20 is detected by the motor current detector 38, and the motor current value i is input to the subtractor 30A and fed back.

  Such an electric power steering apparatus calculates an assist amount in accordance with a steering torque applied from a driver. That is, the steering torque amount input to the steering wheel is detected by a torque sensor, the detected steering torque amount is input to the current command value calculation unit, and the assist command is calculated by the current command value calculation unit.

  Thus, since the torque sensor system plays an important role in the electric power steering apparatus, it is necessary to detect and control abnormality (including failure) of the torque sensor system. As a method for detecting an abnormality of such a torque sensor, there are two torque sensors that determine whether the torque sensor system is normal or abnormal based on the detected torque signal detected by each torque sensor. is there.

  However, when a failure of the torque sensor is detected based on the detected torque signals detected by the two torque sensors, it has not been possible to determine which of the two torque sensors is abnormal. Further, there is a problem that even if an abnormality occurs in one of the two torque sensors, the operation of the apparatus is stopped or an accurate steering torque cannot be detected.

  As an apparatus for solving such a problem, there is an electric power steering apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 11-78924 (Patent Document 1). In the electric power steering apparatus shown in Patent Document 1, even if one torque sensor fails, the steering feeling is not affected by detecting the steering torque with the other torque sensor. That is, the steering torque detecting means is composed of two sets, one set of the steering torque sensor and the steering torque detector having the failure detecting means. When the determination is made, switching means for switching to the other steering torque detection means based on the failure signal from the failure detection means is provided.

In addition, in the electric power steering device disclosed in Japanese Patent Application Laid-Open No. 2003-312507 (Patent Document 2), in order to correct the detected torque signal so as to gradually reduce the assist torque when a torque sensor abnormality occurs, A torque sensor is provided, and when the main torque sensor mainly used for control is clearly broken, correction is performed based on the detected torque signal of the normal sub torque sensor to limit the assist. That is, a plurality of steering torque detecting means for detecting steering torque of the steering, a motor control signal generating means for determining and outputting a motor control signal based on a steering torque detection signal from the steering torque detecting means, and a motor control signal generating means Motor drive means for driving the motor based on the motor control signal from the motor, failure diagnosis means for diagnosing a failure of the steering torque detection means, steering torque input correction means for correcting the steering torque detection signal, and failure diagnosis means And a control target input switching means for switching a steering torque detection signal input to the steering torque input correction means according to the command, and the control target input switching means is configured when any of the plurality of steering torque detection means fails. The steering torque detection signal of other normal steering torque detection means is input to the steering torque input correction means. It has been made.
JP-A-11-78924 JP 2003-31507 A

  However, in the apparatus of Patent Document 1, by using two torque sensors, when the main torque sensor fails, the steering torque is detected by the sub torque sensor so that the steering feeling is not affected. Further, in the apparatus of Patent Document 2, even if an abnormality occurs in both torque sensors, correction is performed based on the stored value immediately before the occurrence of the abnormality in the main torque sensor. That is, since both the device of Patent Document 1 and the device of Patent Document 2 use two torque sensors, there is a problem that the cost is significantly increased.

  For this reason, there is a conventional method for determining abnormality of the torque sensor system based on a plurality of detected torque signals from one torque sensor. However, when an abnormality is detected in any one of the plurality of detected torque signals, the assist is stopped.

  Here, an example of the operation of the conventional apparatus that switches between assist continuation or stop based on two detected torque signals from one torque sensor will be described with reference to the flowchart of FIG.

  Based on the main torque signal Tm and the sub-torque signal Ts from the torque sensor, the control unit includes a diagnosis unit that detects an abnormality in the torque sensor system. The diagnosis unit is preset with the input main torque signal Tm. By comparing the lower limit value VL and the upper limit value VH, an abnormality of the torque sensor system with respect to the main torque signal Tm is diagnosed (step S30). If the main torque signal Tm is larger than the lower limit value VL and smaller than the upper limit value VH, it is considered normal. Therefore, the process proceeds to the next step S31, and when the main torque signal Tm is lower than the lower limit value VL, or the main torque Tm is the upper limit value. If it is equal to or greater than the value VH, it is considered abnormal, so the process proceeds to step S34 and stops while gradually changing the assist. If it is determined in step S30 that it is normal, the diagnosis unit further diagnoses whether the input sub torque signal Ts is in a range larger than the lower limit value VL and smaller than the upper limit value (step S31). If it is within the range, it is determined as normal and the process proceeds to the next step S32. If the sub torque signal Ts is equal to or lower than the lower limit value VL, or if the sub torque signal Ts is equal to or higher than the upper limit value VH, it is determined that there is an abnormality, and the process proceeds to step S34 and stops while gradually changing the assist.

  If it is determined in step S31 that the operation is normal, the diagnosis unit calculates a main-sub tolerance Tp (= | Tm-Ts |) that is a difference between the input main torque signal Tm and the sub torque signal Ts. A diagnosis is performed by comparing the main-sub tolerance Tp and a predetermined value VD set in advance (step S32). If the main-sub tolerance Tp is smaller than the predetermined value VD, it is determined as normal, and the process proceeds to step S33. If the main-sub tolerance Tp is equal to or greater than the predetermined value VD, the process proceeds to step S34, and the assist is gradually changed. Stop. When it is diagnosed as normal in step S32, in order to continue the assist, the main torque signal Tm is input to the current command value calculation unit, and the motor is driven and controlled by the calculated current command value.

  In step S34, since any one of the main torque signal Tm, the sub torque signal Ts, and the main-sub tolerance Tp is diagnosed, the main torque signal Tm is limited by the gain, and the assist is gradually performed. Limit to stop while decreasing.

  Thus, only one torque sensor is installed, and when an abnormality is detected in any one of the detected main torque signal Tm and sub torque signal Ts, the assist is uniformly stopped. It is supposed to be. For this reason, it does not meet the request to continue the assist as much as possible.

  The present invention has been made under the circumstances as described above, and an object of the present invention is to determine abnormality of the torque sensor system based on a plurality of detected torque signals from one torque sensor, and to subdivide the abnormality occurrence site. The object is to provide an electric power steering device capable of expanding the effective range of assist by making the detection and enabling efficient assist control.

  The present invention relates to an electric power steering device that drives and controls a motor that applies assist torque to a steering system based on a plurality of torque signals from a torque sensor and a current command value calculated based on a vehicle speed. An abnormality diagnosis unit for diagnosing and switching abnormality of the plurality of torque signals, a diagnosis auxiliary unit for diagnosing abnormality of the plurality of torque signals, and a torque sensor based on diagnosis results of the abnormality diagnosis unit and the diagnosis auxiliary unit This is achieved by including a diagnosis determination control unit that determines an abnormality of the system and switches the output torque signal.

  In addition, the object of the present invention is that the diagnosis determination control unit switches the continuation of the assist torque application or the assist torque application from gradual change to stop based on the determination result, or the plurality of the plural When the torque signal is a main torque signal and a sub torque signal, and is input to the abnormality diagnosis unit and the diagnosis auxiliary unit, respectively, or the abnormality diagnosis unit outputs the main torque signal, the sub torque signal, the main torque signal, and the sub torque. A first tolerance, which is a signal difference, is compared with a predetermined value to diagnose an abnormality, and the diagnosis assisting unit compares a second tolerance, which is a difference between the main torque signal and the sub torque signal, with the predetermined value. By diagnosing an abnormality, or the abnormality diagnosis unit and the diagnosis auxiliary unit are divided into different hardware, respectively. By being made, it is more effectively achieved.

  According to the electric power steering apparatus of the present invention, an abnormality of the torque sensor system is provided by using an abnormality diagnosis unit and a diagnosis auxiliary unit that provide one torque sensor and divide a plurality of detected torque signals from the torque sensor into different hardware. In addition, it is possible to subdivide the abnormality and identify the part where the abnormality has occurred, and to continue assisting if the abnormality part is within the allowable range. It can be continued.

  The electric power steering apparatus according to the present invention identifies an abnormality occurrence site by diagnosing a plurality of detected torque signals with two abnormality diagnosis units divided into different hardware. Then, in order to allow the assist to be continued if the specified abnormality occurrence site is within the allowable range, it is determined whether or not the range is within the allowable range, and an abnormality diagnosis is performed to switch between assist continuation and assist stop. A determination unit is provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  A configuration example of a diagnosis unit that diagnoses an abnormality of a torque sensor system suitable for carrying out the present invention will be described with reference to FIG. The diagnosis unit of the present invention includes a diagnosis control unit 40 composed of a main CPU and a diagnosis auxiliary unit 50 composed of a sub CPU. The diagnosis control unit 40 comprises an abnormality diagnosis unit 41, a switching unit 42, and an abnormality diagnosis. The determination unit 43 and the control unit 44 are included. The torque signal T2 output from the diagnosis unit 40 and the vehicle speed V from the vehicle speed sensor 12 are input to the motor drive control unit 60, and the motor is driven and controlled by calculating a current command value. The switching unit 42, the abnormality diagnosis determination unit 43, and the control unit 44 constitute a diagnosis determination control unit.

  The main torque signal Tm and the sub torque signal Ts from the torque sensor 10 are input to the abnormality diagnosis unit 41 and the diagnosis auxiliary unit 50 in the diagnosis unit 40, respectively.

  In the abnormality diagnosis unit 41, the input main torque signal Tm and sub torque signal Ts are A / D converted by the A / D conversion units 413 and 414, respectively, and input to the detected torque diagnosis unit 412, and the main torque signal Tm is The sub torque signal Ts is input to the contact c2 of the switching unit 411 to the contact c1 of the switching unit 411.

  The detected torque diagnosis unit 412 diagnoses that the main torque signal Tm is normal if the main torque signal Tm is “VL <Tm <VH” with respect to the preset lower limit value VL and upper limit value VH, and the sub torque signal Ts is “VL <Ts <. If it is “VH”, it is diagnosed as normal. Then, when the main torque signal Tm is “VL ≧ Tm, Tm ≧ VH”, or when the sub torque signal Ts is “VL ≧ Ts, Ts ≧ VH”, an abnormality is diagnosed.

  The detected torque diagnosis unit 412 switches the contact of the switching unit 411 to “c1” when the main torque signal Tm is diagnosed as normal, and switches when the main torque signal Tm is abnormal and the sub torque signal Ts is diagnosed as normal. The switching signal CS1 for switching the contact of the unit 411 to “c2” is output. When the main torque signal Tm and the sub torque signal Ts are both normal, the detected torque diagnosis unit 412 outputs a switching signal CS1 for setting the contact point of the switching unit 411 to “c1”.

  Further, the detected torque diagnosis unit 412 calculates a main-sub tolerance Tp1 (= | Tm-Ts |) which is a difference between the main torque signal Tm and the sub-torque signal Ts, and the main-sub tolerance Tp1 is set in advance. Compared with the predetermined value VD, if it is less than the predetermined value (Tp1 <VD), it is diagnosed as normal, and if it is greater than the predetermined value (Tp1 ≧ VD), it is diagnosed as abnormal. Each diagnosis result of the main torque signal Tm, the sub torque signal Ts, and the main-sub tolerance Tp1 in the detected torque diagnosis unit 412 is input to the abnormality diagnosis determination unit 43 as a diagnosis signal D1.

  In the diagnosis assisting unit 50, the main torque signal Tm and the sub torque signal Ts are A / D converted by the A / D conversion units 51 and 52, respectively, and input to the detected torque diagnosis assisting unit 53. The detected torque diagnosis auxiliary unit 53 calculates a main-sub tolerance Tp2 (= | Tm-Ts |) which is a difference between the input main torque signal Tm and the sub-torque signal Ts, and calculates the main-sub tolerance Tp2. Compared with a predetermined value VD set in advance, if it is less than the predetermined value (Tp2 <VD), it is diagnosed as normal, and if it is equal to or greater than the predetermined value (Tp2 ≧ VD), it is diagnosed as abnormal. The diagnosis result of the main-sub tolerance Tp2 in the diagnosis auxiliary unit 50 is input from the diagnosis auxiliary unit 50 to the abnormality diagnosis determination unit 43 as the diagnostic signal D2.

  The abnormality diagnosis determination unit 43 switches the contact c3 and the contact c4 of the switching unit 42 with the switching signal CS2 based on the diagnosis signal D1 from the abnormality diagnosis unit 41 and the diagnosis signal D2 from the diagnosis auxiliary unit 50, thereby controlling the control unit The control 44 is switched to the assist continuation control 441 or the assist stop control 442 for stopping the assist while gradually decreasing the assist.

  When the contact of the switching unit 42 is “c3” based on the switching signal CS2 from the abnormality diagnosis determination unit 43, the torque signal T1 from the switching unit 411 passes through the assist continuation control 441 in the control unit 44, that is, any assist limitation. Is input to the motor drive control unit 60 without being added. Further, when the contact of the switching unit 42 is “c4” based on the switching signal CS2 from the abnormality diagnosis determination unit 43, the torque signal T1 from the switching unit 411 passes through the assist stop control 442 in the control unit 44, and the torque signal T1 is The output is gradually reduced in proportion to the time, is limited by a gain so as to stop before long, and is input to the motor drive control unit 60.

  In such a configuration, an example of the operation will be described with reference to the flowchart of FIG.

  The main torque signal Tm and the sub torque signal Ts from the torque sensor 10 are input to the abnormality diagnosis unit 41 and the diagnosis auxiliary unit 50.

  The main torque signal Tm and the sub torque signal Ts A / D converted by the A / D conversion units 413 and 414 are input to the detected torque diagnostic unit 412 and the switching unit 411, and the detected torque diagnostic unit 412 connects the switching unit 411 to the contact c1. And the torque signal T1 from the abnormality diagnosis unit 41 is set as the main torque signal Tm (step S10). The detected torque diagnosis unit 412 compares the input main torque signal Tm with the lower limit value VL and the upper limit value VH set in advance, and diagnoses whether or not “VL <Tm <VH” (step S11). ). If the main torque signal Tm is “VL <Tm <VH”, the process proceeds to Step 12, and if “VL <Tm <VH” is not satisfied, the process proceeds to Step S14.

  In step S12, the detected torque diagnosing unit 412 compares the sub torque signal Ts with the lower limit value VL and the upper limit value VH set in advance, diagnoses whether or not “VL <Ts <VH”, and the sub torque signal Ts is “ If VL <Ts <VH, the process proceeds to step 13. If “VL <Ts <VH” is not satisfied, a diagnostic signal D1 is output, in which the main torque signal Tm is normal but the sub torque signal Ts is abnormal. Then, the process proceeds to step S16.

  When “VL <Ts <VH” in step S12, the detected torque diagnosis unit 412 compares the calculated main-sub tolerance Tp1 with the predetermined value VD and the main-sub tolerance Tp1 is smaller than the predetermined value VD. (Tp1 <VD), the diagnosis is normal, the main torque signal Tm, the sub torque signal Ts, and the main-sub tolerance Tp1 are normal, and the diagnosis signal D1 is output, and the process proceeds to step S17 (step S13). On the other hand, if the main-sub tolerance Tp1 is greater than or equal to the predetermined value VD in step S13, a diagnostic signal D1 is output in which the main torque signal Tm and the sub-torque signal Ts are normal and the main-sub tolerance Tp1 is abnormal. Control goes to step S16.

  On the other hand, when the main torque signal Tm does not satisfy “VL <Tm <VH” in step S11, the detected torque diagnosis unit 412 compares the sub torque signal Ts with the lower limit value VL and the upper limit value VH set in advance. It is diagnosed whether or not VL <Ts <VH ”(step S14). When the sub torque signal Ts is “VL <Ts <VH”, the detected torque diagnosis unit 412 outputs a diagnosis signal D1 of the diagnosis result that the main torque signal Tm is abnormal and the sub torque signal Ts is normal, and the process proceeds to step S15. Transition. When the sub torque signal Ts does not satisfy “VL <Ts <VH”, the detected torque diagnosis unit 412 outputs the diagnosis signal D1 of the diagnosis result indicating that the main torque signal Tm and the sub torque signal Ts are abnormal, and the process proceeds to step S18. Transition.

  When the sub torque signal Ts satisfies “VL <Ts <VH” in step S14, the detected torque diagnosis unit 412 outputs the switching signal CS1 for switching the contact of the switching unit 411 to “c2”, and the torque used for assist control. The signal T1 is set to the sub torque signal Ts (step S15). Thereafter, or when “VL <Ts <VH” is not satisfied in step S12, or when the main-sub tolerance Tp1 is greater than or equal to the predetermined value VD in step S13, the detected torque diagnosis auxiliary unit 53 detects the main torque signal Tm. The main-sub tolerance Tp2, which is the difference between the sub-torque signal Ts and the sub-torque signal Ts, is calculated, and the main-sub tolerance Tp2 is compared with the predetermined value VD (step S16). If the main-sub tolerance Tp2 is smaller than the predetermined value VD (Tp2 <VD), the diagnostic signal D2 indicating that the main-sub tolerance Tp2 is normal is output, and the process proceeds to step S17. The main-sub tolerance Tp2 Is equal to or greater than the predetermined value VD, a diagnostic signal D2 is output as a diagnostic result indicating that the main-sub tolerance Tp2 is abnormal, and the process proceeds to step S18.

  The abnormality diagnosis determination unit 43 inputs the switching signal CS2 to the switching unit 42 based on the input diagnostic signals D1 and D2 and switches to the contact c3 or c4. However, when the assist is continued in step S17, the abnormality diagnosis determination unit 43 sets the contact c3. When the assist is stopped, a switching signal CS2 is output as a contact c4.

  An example of the determination result in the above-described configuration example will be described with reference to FIG. Further, “◯” shown in FIG. 3 represents normality, “x” represents abnormality, and “−” represents no diagnosis.

  3 is a determination example in which the main torque signal Tm, the sub torque signal Ts, and the main-sub tolerance Tp1 are all normal in the abnormality diagnosis unit 41, and the determination example in which the abnormality diagnosis determination unit 43 is also determined to be normal. It is. That is, the main torque signal Tm is input from the abnormality diagnosis unit 41 to the switching unit 42 as the torque signal T1, the abnormality diagnosis determination unit 43 sets the contact of the switching unit 42 to “c3”, and continues the assist through the assist continuation control 441. It is a state to do.

  The determination example 2 is a determination example when the abnormality diagnosis unit 41 determines that the main torque signal Tm is normal and the sub torque signal Ts is abnormal. Since the sub torque signal Ts is diagnosed as abnormal, the determination of the abnormality diagnosis determination unit 43 is determined by the diagnosis result of the main-sub tolerance Tp2 in the diagnosis auxiliary unit 50. That is, when the main diagnosis signal Tm is diagnosed as normal in the abnormality diagnosis unit 41, the sub torque signal Ts is diagnosed as abnormal, and the main-sub tolerance Tp2 is diagnosed as abnormal in the diagnosis auxiliary unit 50, the abnormality diagnosis determination unit An abnormality is determined by 43, the contact of the switching unit 42 is switched to "c4", and the assist is stopped from the gradual change of assist through the assist stop control. On the other hand, when the diagnosis auxiliary unit 50 diagnoses that the main-sub tolerance Tp2 is normal, the abnormality diagnosis determination unit 43 determines normality, the contact of the switching unit 42 is switched to “c3”, and the main torque signal Tm The assist is continued based on the torque signal T1.

  The determination example 3 is a determination example when the main diagnosis signal Tm is diagnosed as abnormal in the abnormality diagnosis unit 41 and the sub torque signal Ts is diagnosed as normal. Since the main torque Tm is diagnosed as abnormal, the determination of the abnormality diagnosis determination unit 43 is determined by the diagnosis result in the diagnosis auxiliary unit 50. That is, even if the abnormality diagnosis unit 41 diagnoses that the sub torque signal Ts is normal, the main torque signal Tm is diagnosed as abnormal, and further, the main-sub tolerance Tp2 in the diagnosis auxiliary unit 50 is diagnosed as abnormal. Then, the abnormality diagnosis determination unit 43 determines the abnormality, the contact of the switching unit 42 is switched to “c4”, and the assist is stopped. On the other hand, when the main-sub tolerance Tp2 in the diagnosis auxiliary unit 50 is diagnosed as normal, the abnormality diagnosis determination unit 43 determines normality, the contact of the switching unit 42 is switched to “c3”, and the sub torque signal Ts The assist continuation control is performed based on the torque signal T1.

  The determination example 4 is a determination example when the abnormality diagnosis unit 41 diagnoses that the main torque signal Tm and the sub torque signal Ts are normal and the main-sub tolerance Tp1 is diagnosed as abnormal. Since the main-sub tolerance Tp1 is diagnosed as abnormal, the determination of the abnormality diagnosis determination unit 43 is determined by the diagnosis result of the diagnosis auxiliary unit 50. That is, if the diagnosis auxiliary unit 50 diagnoses that the main-sub tolerance Tp2 is abnormal, it is predicted that either the main torque signal Tm or the sub torque signal Ts is abnormal. A determination is made, the contact of the switching unit 42 is switched to “c4”, and the assist is stopped. However, when the diagnosis auxiliary unit 50 diagnoses that the main-sub tolerance Tp2 is normal, the abnormality diagnosis determination unit 43 determines normality, the contact of the switching unit 42 is switched to “c3”, and the main torque signal Tm. Assist continuation control based on the torque signal T1.

  The determination example 5 is a determination example when the abnormality diagnosis unit 41 determines that the main torque signal Tm and the sub torque signal Ts are abnormal. That is, since both the abnormality diagnosis unit 41 and the diagnosis auxiliary unit 50 have diagnosed the abnormality of the main torque signal Tm and the sub torque signal Ts, the abnormality diagnosis determination unit 43 determines the abnormality, and the contact of the switching unit 42 is “c4”. The assist is stopped.

  Further, in the determination result (conventional), it is possible to determine that only the determination example 1 is normal, and all of the determination examples 3 to 5 are determined to be abnormal. Therefore, the effective control of the present invention is obvious. Result.

  Here, as in the determination example 3, when an abnormality occurs in the main torque signal Tm input to the abnormality diagnosis unit 41, for example, the A / D conversion unit 413 A / D for reading the voltage value of the main torque signal Tm. It is conceivable that an abnormality occurs in the D conversion port and the voltage to be read is out of range. When the main torque signal Tm is diagnosed as abnormal in a state that is not directly related to the failure or abnormality of the torque sensor as described above, an abnormality diagnosis determination unit is provided to continue the assist if the abnormality is within the allowable range. 43 is configured to make a determination based on the diagnosis result in the diagnosis auxiliary unit 50. In other words, if the diagnosis auxiliary unit 50 has diagnosed that the main-sub tolerance Tp2 is normal, the torque sensor 10 is normal, and an abnormality has occurred in the portion of the abnormality diagnosis unit 41 that detects the main torque signal Tm. In order to make the determination and continue the assist, the abnormality diagnosis determination unit 43 sets the contact of the switching unit 42 to “c3” and continues the assist using the sub torque signal Ts.

  The detected torque diagnosis assisting unit 53 of the diagnosis assisting unit 50 may further diagnose abnormality of the main torque signal Tm and the sub torque signal Ts, and two torque sensors use a plurality of detected torque signals. Thus, the abnormality detection accuracy can be improved even when the abnormality is diagnosed.

It is a block diagram which shows the structural example of the diagnostic part of the electric power steering apparatus which concerns on this invention. It is a flowchart which shows the operation example of this invention. It is a figure which shows the example of the determination result which concerns on this invention. It is a block diagram which shows the structural example of the conventional electric power steering apparatus. It is a block diagram which shows the structural example of the conventional control unit. It is a flowchart which shows the operation example which detects abnormality of the conventional torque sensor.

Explanation of symbols

1 Handle 10 Torque sensor 12 Vehicle speed sensor 20 Motor 30 Control unit 40 Main CPU
41 Abnormality Diagnosis Unit 42 Switching Unit 43 Abnormality Diagnosis Determination Unit 44 Control Unit 50 Sub CPU
51 A / D Conversion Unit 52 A / D Conversion Unit 53 Detected Torque Diagnosis Auxiliary Unit 60 Motor Drive Control Unit 411 Switching Unit 412 Detected Torque Diagnosis Unit 413 A / D Conversion Unit 414 A / D Conversion Unit

Claims (5)

In an electric power steering device that drives and controls a motor that applies assist torque to a steering system based on a plurality of torque signals from a torque sensor and a current command value that is calculated based on the vehicle speed, the abnormality of the plurality of torque signals is diagnosed. An abnormality diagnosis unit for switching, a diagnosis auxiliary unit for diagnosing abnormality of the plurality of torque signals, an abnormality of the torque sensor system based on a diagnosis result of the abnormality diagnosis unit and the diagnosis auxiliary unit, and an output torque signal An electric power steering apparatus comprising a diagnosis determination control unit for switching. The electric power steering apparatus according to claim 1, wherein the diagnosis determination control unit switches the continuation of the assist torque application or the assist torque application from gradual change to stop based on the determination result. The electric power steering apparatus according to claim 1 or 2, wherein the plurality of torque signals are a main torque signal and a sub torque signal, and are input to the abnormality diagnosis unit and the diagnosis auxiliary unit, respectively. The abnormality diagnosis unit compares the main torque signal, the sub torque signal, and a first tolerance, which is a difference between the main torque signal and the sub torque signal, with a predetermined value to diagnose an abnormality, and the diagnosis auxiliary unit detects the main torque. The electric power steering apparatus according to claim 3, wherein an abnormality is diagnosed by comparing a second tolerance, which is a difference between a signal and the sub torque signal, with the predetermined value. The electric power steering apparatus according to any one of claims 1 to 4, wherein the abnormality diagnosis unit and the diagnosis auxiliary unit are configured separately on different hardware.

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