JP5298478B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus for a vehicle, and in particular, a reference determination value and a reference determination period for determining abnormality and normality of information output from a component involved in control of the control apparatus according to the state of the vehicle. The present invention relates to an electric power steering apparatus provided with an abnormality / normality detection device that can appropriately detect abnormality detection of components involved in control and normal recovery after abnormality detection.

  An electric power steering device for a vehicle detects a steering torque and a vehicle speed generated in a steering shaft by operating a steering handle, and drives a motor based on the detection signal to assist a steering force of the steering handle. is there. Such control of the electric power steering device is executed by a control device constituted by a microcomputer. The outline of the control is based on the steering torque detected by the torque sensor and the vehicle speed detected by the vehicle speed sensor. The magnitude of the current supplied to the motor is calculated, and the current supplied to the motor is controlled based on the calculation result.

  That is, when the steering wheel is operated and steering torque is generated, the control device supplies a large steering assist force when the detected vehicle speed is zero or low, and small when the detected vehicle speed is high. Calculate the motor current control target value according to the steering wheel steering force and vehicle speed so as to supply steering assist force, and perform feedback control so that the current that actually flows to the motor matches the motor current control target value. The optimal steering assist force according to the running state is given.

  For example, when a failure occurs in the torque sensor due to some cause, the control target value of the motor current cannot be calculated, and the optimum steering assist force cannot be applied to the steering device. In this case, in the conventional device, the steering assist by the motor is stopped, thereby preventing the malfunction of the steering device and avoiding danger.

  Further, when the motor or the motor drive circuit breaks down and an overcurrent flows through the motor, the motor or the motor drive circuit is burned out. Also in this case, in the conventional apparatus, the power supply to the motor is stopped and the steering assist by the motor is stopped, thereby avoiding a danger such as a fire.

As described above, the conventional control device for the electric power steering apparatus is provided with an abnormality detection means having a fail-safe function for stopping the steering assist by the motor when an abnormality is detected, thereby avoiding a serious danger. It was comprised so that it might do (refer patent document 1).
Japanese Patent Laid-Open No. 2003-200842

  In the abnormality determination means of the above-described conventional abnormality detection device, information indicating the operation state of various components involved in the control of the control device, for example, if the component is a torque sensor, the detected steering torque value is an abnormal value. Over a predetermined judgment reference value (or a predetermined number of judgments) for more than a predetermined judgment reference time (or a predetermined number of judgments). Even if is set, the center value is a constant value.

  Further, in the normal return determination means after abnormality detection provided in the conventional abnormality detection means, information indicating the operation state of various components (for example, if the component is a torque sensor, the detected steering torque value) Is in a normal range (predetermined criterion value range) is determined to have returned to normal when it continues for a predetermined criterion time (or a predetermined number of times). Even if an allowable error range is set for the determination reference time, the center value is a constant value.

  For this reason, even if the failed components are the same, depending on the state of the vehicle at the time of occurrence of an abnormality or normal recovery, for example, when the vehicle speed is extremely low, the driver may feel a sense of discomfort when operating the steering wheel. Even when the vehicle is traveling at a high speed, the steering handle may move unintentionally by the driver, which may cause inconvenience that the driver may feel uncomfortable with the steering wheel operation. An object of the present invention is to solve the above-described problems.

The present invention is intended to solve the above problems, an electric power steering apparatus provided with a control device for controlling a motor output providing a steering assist force to a steering mechanism of the vehicles, the operation of the components involved in the control of the control device An operation state information detection unit for detecting operation state information indicating a state, and an abnormality / normality determination unit for determining abnormality of a component member involved in the control of the control device and normal return after abnormality determination, The abnormality / normality determination unit compares the detected operation state information indicating the operation state of the component member with reference determination information set in advance based on the operation environment of the component member, and is involved in control of the control device. An electric power steering apparatus characterized by determining abnormality of a component and / or determining normal return after abnormality determination.

  The reference determination information includes information for determining whether or not the operation state information is within a predetermined normal operation state range, and when the operation state information is within a predetermined normal operation state range, Is determined to be continued over a predetermined reference determination time, information for determining whether the state is maintained beyond a predetermined reference determination count, and operation state information is predetermined normal When it is not within the range of the operating state, information for determining whether or not the state has continued for a predetermined reference judgment time or whether the state has been maintained for a predetermined number of reference judgments or not Information.

  Further, the reference determination information is changed according to the operating environment of the constituent members involved in the control of the control device.

  The operating environment of the constituent members involved in the control of the control device may be a vehicle speed.

  Then, the abnormality / normality determination unit compares the operation state information with the reference determination information, the operation state information is not within a predetermined normal operation state range, and the state has a predetermined reference determination time. When it is continued beyond, or when the state is continued beyond a predetermined reference determination number, it is determined that a component related to the control of the control device is abnormal.

  Then, the abnormality / normality determination unit compares the operation state information with the reference determination information, the operation state information is not within a predetermined normal operation state range, and the state has a predetermined reference determination time. If it is continued beyond or when the state continues beyond a predetermined reference determination number, it is determined that the component related to the control of the control device is abnormal, and the operation state information is predetermined normal A configuration that is involved in the control of the control device when it is within the range of the operating state and the state continues for a predetermined reference determination time or when it exceeds the predetermined reference determination number of times. It is determined that the member has returned to a normal state.

  The operation state information of the constituent members involved in the control of the control device may be a steering torque detected by a torque sensor.

  Further, the operation state information of the constituent members involved in the control of the control device may be a motor current detected by a motor current detection device.

  In the abnormality / normality determination unit, a mask condition for stopping the abnormality detection operation can be set in advance according to the vehicle speed.

  In addition, the control device may operate the fail-safe function and cut off the power supply to the motor when the abnormality / normality determination unit determines that the operation state information is abnormal.

  Further, the control device may continue the control based on a predetermined initial value instead of the operation state information when the operation state information is determined to be abnormal by the abnormality / normality determination unit.

  In addition, the operation state information detection unit detects operation state information of components related to control of the control device every predetermined time.

  According to the present invention, in an electric power steering apparatus including a control device that controls a motor output that applies a steering assist force to a steering mechanism of a vehicle, operation state information indicating an operation state of a component that is involved in the control of the control device is detected. And an abnormality / normality determination unit that determines abnormality determination of component members involved in control of the control device and normal return after abnormality determination, and the abnormality / normality determination unit includes the configuration After comparing the operation state information indicating the operation state of the member with the reference determination information set in advance based on the operation environment of the component member, determining the abnormality of the component member involved in the control of the control device, and after the abnormality determination It is characterized in that a normal return is determined.

  The reference determination information includes information indicating whether the operation state information is within a predetermined normal operation state range, and when the operation state information is within a predetermined normal operation state range, Information indicating whether or not a predetermined reference determination time has been exceeded, or information indicating whether or not the state has been maintained beyond a predetermined reference determination number, and the reference determination information is a control device It changes according to the operating environment of the components involved in the control of the vehicle, that is, the state of the vehicle, and is set to the optimum value / optimum time or the optimum number of times, so that the behavior of the vehicle unintended by the driver can be reduced. Thus, it is possible to provide an electric power steering apparatus that can ensure a safe steering handle operation without giving the driver a feeling of strangeness in the steering handle operation.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram for explaining an outline of the configuration of an electric power steering apparatus suitable for carrying out the present invention. A shaft 2 of a steering handle 1 passes through a reduction gear 4, universal joints 5a and 5b, and a pinion rack mechanism 7. Coupled to the steering wheel tyrod 8. A torque sensor 3 that detects the steering torque of the steering handle 1 is provided on the shaft 2, and a motor 9 that assists the steering force is coupled to the shaft 2 via a reduction gear 4.

  The control device 10 for controlling the power steering device is supplied with an ignition key signal from the battery 14 via the ignition key 11 and is supplied with power from a parallel power supply line. The control device 10 calculates a current command value based on the steering torque detected by the torque sensor 3 and the vehicle speed detected by the vehicle speed sensor 12, and generates a current i supplied to the motor 9 based on the calculated current command value. Control.

  FIG. 2 is a block diagram showing the configuration of the control device 10 and its peripheral circuits. In this embodiment, the main part of the control device 10 is constituted by a CPU. Here, functions executed by programs in the CPU are shown. For example, the phase compensator 21 does not indicate the phase compensator 21 as independent hardware, but indicates a phase compensation function executed by the CPU. Needless to say, these functional elements can be configured by independent hardware (electronic circuits) without configuring the control device 10 by a CPU.

  Hereinafter, functions and operations of the control device 10 will be described. The steering torque signal input from the torque sensor 3 is phase-compensated by the phase compensator 21 in order to increase the stability of the steering system, and input to the current command calculator 22. The vehicle speed detected by the vehicle speed sensor 12 is also input to the current command value calculator 22.

  The current command value calculator 22 determines a current command value I that is a control target value of the current supplied to the motor 9 by a predetermined calculation formula based on the input torque signal and vehicle speed signal.

  A circuit composed of the comparator 23, the differential compensator 24, the proportional calculator 25, and the integral calculator 26 is a circuit that performs feedback control so that the actual motor current value i matches the current command value I.

  The proportional calculator 25 outputs a proportional value proportional to the difference between the current command value I and the actual motor current value i. Further, the output signal of the proportional calculator 25 is integrated in the integral calculator 26 in order to improve the characteristics of the feedback system, and a proportional value of the difference integral value is output.

  The differential compensator 24 outputs the differential value of the current command value I in order to increase the response speed of the motor current value i that actually flows through the motor with respect to the current command value I calculated by the current command value calculator 22.

  The differential value of the current command value I output from the differential compensator 24, the proportional value proportional to the difference between the current command value output from the proportional calculator 25 and the actual motor current value, and the integral calculator 26 The added value is added by the adder 27 and a current control value E (duty ratio of the PWM signal that determines the motor applied voltage) as the calculation result is output to the motor drive circuit 41. The actual current flowing through the motor 9 is detected by the motor current detection circuit 42, and the detected motor current value i is fed back to the comparator 23, and feedback control of the motor current is performed.

  The operation state information detection unit 31 detects operation state information of the constituent members involved in the control of the control device, and the constituent members involved in the control of the control device are, for example, a torque sensor and a motor current detection device, The operating state information is a steering torque when the constituent member involved in the control is a torque sensor, and the motor current when the constituent member involved in the control is a motor current detection device.

  The operating state information detection unit 31 receives the steering torque T detected by the torque sensor 3, the motor current i detected by the motor current detection circuit 42, and the motor angular velocity φ detected by the motor angular velocity sensor 30.

  The reference determination information storage unit 35 stores reference determination information set in advance based on the operating environment of the constituent members, for example, the vehicle speed. The reference determination information is information for determining whether or not the component member is abnormal, and determining whether or not normal recovery has been performed after the abnormality determination.

  The abnormality determination / normality determination unit 32 is connected to the reference determination information storage unit 35, the operation state information detected by the operation state information detection unit 31, and the reference determination information stored in the reference determination information storage unit 35. To determine whether or not a component involved in the control of the control device, for example, a torque sensor or a motor current detection device is abnormal, and whether or not normality is restored after the abnormality is determined.

  The fail-safe processor 33 and the motor relay 34 indicate that the determination result determined by the abnormality / normality determination unit 32 indicates that a component related to control of the control device, for example, a torque sensor, a motor, or a motor drive circuit is abnormal. In this configuration, fail-safe processing is performed using a signal indicating the determination result as an input.

    The operations of the operation state information detection unit 31, the abnormality / normality determination unit 32, the fail safe processor 33, and the motor relay 34 will be described in detail later based on examples.

  FIG. 3 shows an example of the configuration of the motor drive circuit 41. The motor drive circuit 41 includes a conversion unit 45 that separates and converts the current control value input from the adder 27 into a PWM signal and a current direction signal, FET1 to FET4, and an FET gate drive circuit 46 that opens and closes the gates of these. Consists of. The step-up power supply 47 is a power supply for driving the high side of the FET1 and FET2.

  The PWM signal (pulse width modulation signal) is a signal for driving the gates of FET (field effect transistor) switching elements FET1 to FET2 connected to the H-bridge, and the PWM signal is obtained by the absolute value of the current control value calculated in the adder 27. The duty ratio D (time ratio for turning on / off the FET gate) is determined.

  In the normal running state, the duty ratio D is determined based on the calculated current control value E as described above.

  The current direction signal is a signal indicating the direction of the current supplied to the motor, and is a signal determined by the sign (positive / negative) of the current control value calculated by the adder 27.

  FET1 and FET2 are switching elements whose gates are turned ON / OFF based on the duty ratio of the PWM signal described above, and are switching elements for controlling the magnitude of the current flowing through the motor. FET3 and FET4 are switching elements whose gates are turned on or off based on the current direction signal described above (one is turned on when the other is turned on), and the direction of the current flowing through the motor, that is, the direction of rotation of the motor. Switching element for switching between

  When FET3 is in a conducting state, current flows through FET1, motor 9, FET3, and resistor R, and a positive current flows through motor 9. When the FET 4 is in a conductive state, the current flows through the FET 2, the motor 9, the FET 4, and the resistor R, and a negative current flows through the motor 9.

  The motor current detection circuit 42 constituting the motor current detection means detects the current magnitude based on the voltage drop across the resistor R. The detected actual motor current value is fed back and input to the comparator 23 (see FIG. 2).

  The control device described above increases the detected steering torque when the steering handle is operated and generates the steering torque, and increases the current command value I when the detected vehicle speed is zero or low. When the detected steering torque is small and the detected vehicle speed is high, the current command value I is set small, so that the optimum steering assist force according to the traveling state can be applied.

  Next, in the operation state information detection unit 31, the abnormality / normality determination unit 32, and the fail safe processor 33 of the control device 10, the abnormality determination processing of various components involved in the control of the control device, and the normality after the abnormality determination The return determination process and the fail safe process based on the abnormality determination result will be described.

  As described above in the problem to be solved by the invention, in the abnormality determination means of the control device having the conventional fail-safe function, information indicating the operation state of various components involved in the control of the control device, for example, the configuration If the member is a torque sensor, it is determined as abnormal when the detected steering torque value exceeds an abnormal value, that is, when a state exceeding a predetermined determination reference value continues for a predetermined determination reference time. Even if a predetermined allowable error range is set for the above-described determination reference value or determination reference time, the center value thereof is a constant value.

  For this reason, when the vehicle is in an abnormal state, for example, when the vehicle speed is extremely low, the steering handle is not In some cases, an unintended movement may occur, causing the driver to feel uncomfortable with the steering wheel operation.

  Therefore, in the present invention, the determination criterion information for determining whether or not the operation state information of various components related to the control of the control device indicates an abnormal value is determined according to the operation environment of the component related to the control of the control device. For example, if the constituent member is a torque sensor or a motor current detector, the determination reference information is changed according to whether the vehicle speed, which is the operating environment at that time, is extremely low speed / intermediate speed / high speed, etc. It solves the inconvenience.

  In addition, the information regarding the operation state of the structural member involved in the control of the control device is repeatedly sampled every predetermined time, and abnormality determination of various structural members is performed.

  Hereinafter, the failure determination process based on the abnormality determination of various components, the normal return determination after the abnormality determination, and the abnormality determination result according to the first to third embodiments will be described.

[First embodiment]
1st Example is an Example which determines the abnormality of the torque sensor which is one of the structural members which are concerned with control of a control apparatus. First, a method for determining abnormality of the torque sensor will be described.

  FIG. 4 is a diagram for explaining the relationship between the steering torque (hereinafter referred to as torque) required when the steering handle is steered by a predetermined angle and the vehicle speed, where the horizontal axis is the vehicle speed V and the vertical axis is the torque detection. The value d. Until the vehicle speed V is a relatively low vehicle speed SP2, the torque detection value d decreases due to friction between the road surface and the tire. However, when the vehicle speed SP2 is exceeded, the straightness of the vehicle increases, so the torque detection value d increases slightly. It is known to do.

  FIG. 5 is a diagram for explaining a determination reference value set by a conventional torque detection value d abnormality determination method. The horizontal axis represents the vehicle speed V, the vertical axis represents the torque detection value d, and the torque normal / abnormal determination reference value da. (Hereinafter referred to as determination criterion value). The conventional determination reference value da is set to a constant value regardless of the vehicle speed V as shown in FIG. 5, and when the detected torque value d is in the abnormality determination region Da above the determination reference value da, torque detection is performed. It was determined that the value d was abnormal, that is, the torque sensor was abnormal. Note that a predetermined allowable error range, that is, a detection margin m is set for the determination reference value da to prevent erroneous detection.

  Specific examples will be described below. When an abnormality occurs in the torque sensor, which is a constituent member involved in the control of the control device, and the detected torque value at the position A in FIG. 5 moves to the position B, the abnormality determination region above the determination reference value da Therefore, it is detected that the torque detection value is abnormal, that is, that an abnormality has occurred in the torque sensor. After this, if the torque sensor is abnormal and the torque detection value is slightly decreased and moved to the position C, the torque detection value is normal because it enters the normal determination region below the determination reference value da. As a result, the torque sensor is erroneously determined to have returned to normal.

  Therefore, in the present invention, the determination reference information (here, the torque normal / abnormal determination reference value da) is changed and set according to whether the vehicle speed at that time is extremely low / intermediate speed / high speed.

  FIG. 6 shows the setting of torque normal / abnormal determination reference value (hereinafter referred to as determination reference value) da and torque abnormality determination reference time (hereinafter referred to as determination reference time) ta for determining abnormality of the torque detection value d of the first embodiment. In the figure for explaining an example, the horizontal axis represents the vehicle speed V, the vertical axis represents the torque detection value d, the determination reference value da for determining torque abnormality, and the determination reference time ta (the vertical axis on the right side in FIG. 6). A predetermined allowable error range, that is, a detection margin m is set for the determination reference value da and the determination reference time ta to prevent erroneous detection.

  In FIG. 6, the set determination reference value da and the determination reference time ta are indicated by the same broken line. However, the determination reference value da and the determination reference time ta may be different from each other by a broken line or a curved line. In addition, the determination reference value da and the determination reference time ta may be different from each other in a polygonal line or a curve. Here, an example of the determination reference value da and the determination reference time ta is shown.

  The abnormality determination area is divided into a plurality of areas in accordance with the vehicle speed. The first determination area D1 is from 0 to the vehicle speed SP1, the second determination area D2 is from the vehicle speed SP1 to the vehicle speed SP2, and the high speed area is greater than the vehicle speed SP2. Then, it is set as the third determination area D3. In the first determination area D1, a fixed determination reference value da1 and determination reference time ta1 are set. In the second determination area D2, a determination reference value da2 and a determination reference time ta2 that decrease as the vehicle speed increases are set, and in the third determination area D3, a determination reference value da3 that increases as the vehicle speed increases. A reference time ta3 is set.

  In order to cope with a special steering pattern, a constant determination reference value da1 and a determination reference time ta1 are set as the determination reference value in the first determination region D1 regardless of the vehicle speed. In the first determination region D1 from zero to the vehicle speed SP1, it is assumed that the torque becomes abnormally large due to steering of the handlebars or strong end-to-end torsion during turning. Therefore, a relatively large constant determination criterion value da1. The determination reference time ta1 is set, and the detection margin m is also set relatively large.

  In the second determination area D2, as described above, the torque tends to decrease as the vehicle speed increases. Therefore, a determination reference value da2 and a determination reference time ta2 that decrease as the vehicle speed increases are set and detected. The margin m is also set so as to decrease as the vehicle speed increases.

  Further, during high speed traveling, it is normally impossible for large torque to be generated. Therefore, in the third determination region D3, which is a high speed region, a determination reference value da3 and a determination reference time ta3 that increase as the vehicle speed increases are set. The detection margin m is set to be substantially constant.

  Specific examples will be described below. When an abnormality occurs in the torque sensor, which is a constituent member involved in the control of the control device, and the detected torque value at the position A in FIG. 6 moves to the position B, an abnormality determination region above the determination reference value da. Therefore, it is detected that the torque detection value is abnormal, that is, that an abnormality has occurred in the torque sensor. After this, even though the torque sensor is abnormal, even if the torque detection value decreases slightly and moves to the position C, the torque detection value is abnormal because it is in the abnormality determination region above the determination reference value da. The torque sensor is determined to be abnormal and there is no risk of erroneous determination.

  Thereafter, if the torque detection value further decreases and moves to the position A, the torque detection value falls below the determination reference value da2 and falls within the normal value range. At this time, this state (torque detection value is It is determined whether or not the condition below the determination reference value da2 has continued beyond the predetermined determination reference time ta2, and when it has been confirmed that it has continued beyond the predetermined determination reference time ta2, the torque sensor returns to normal. It is determined that

  In addition, after the torque detection value becomes equal to or less than the determination reference value, instead of determining whether or not this state continues beyond a predetermined determination reference time, the torque detection value that is repeatedly sampled is equal to or less than the determination reference value. When it is confirmed that the state has been maintained beyond a predetermined number of determination criteria, it may be determined that the torque sensor has returned to normal.

  In the high-speed travel region, the torque abnormality determination reference value is set small and the abnormality determination region is expanded, so that abnormality detection is performed with a small torque value, and abnormality can be detected early while preventing erroneous detection. As a result, when an abnormality occurs in the torque sensor during high-speed traveling, the abnormality can be detected at an early stage, and the behavior of the vehicle unintended by the driver can be suppressed.

  In the first embodiment described above, the determination reference value da is a vehicle speed sensitive type that changes according to the vehicle speed. However, the determination reference value da may be kept constant and the determination reference time ta may be a vehicle speed sensitive type. In this case, the determination reference value da may be set to a constant value regardless of the vehicle speed in the low speed region, and the determination reference time ta may be set short in response to the increase in the vehicle speed in the high speed region. Further, both the determination reference value da and the determination reference time ta for abnormality determination may be a vehicle speed sensitive type.

  Further, the determination reference value da and the determination reference time ta may be stored in advance in a storage device in the form of a look-up table according to the vehicle speed and referred to when performing abnormality determination. In addition, a basic determination reference value and a basic determination reference time are set in advance, and a vehicle speed is calculated by multiplying the basic determination reference value and the basic determination reference time by a coefficient set in advance according to the vehicle speed when the abnormality determination is performed. It is also possible to calculate a determination reference value or a determination reference time according to the above.

  With reference to FIG. 2, the configuration and operation for detecting a failure of the torque sensor 3 which is one of the components of the electric power steering apparatus of the first embodiment and performing fail-safe processing based on the detection result will be described.

  The reference determination information storage unit 35 stores the above-described determination reference value da and determination reference time ta as reference determination information set in advance, and a vehicle speed signal detected by the vehicle speed sensor 12 is input. Then, the determination reference value da and the determination reference time ta according to the vehicle speed are output to the abnormality / normality determination unit 32 described later.

  The operation state information detection unit 31 receives the steering torque detection value d detected by the torque sensor 3 and outputs it to the abnormality / normality determination unit 32.

  The abnormality / normality determination unit 32 receives the steering torque detection value d output from the operation state information detection unit 31, the determination reference value da and the determination reference time ta output from the reference determination information storage unit 35, and In order to determine the elapsed time (or the number of times of determination reference) of the determination reference time ta, the elapsed time (or determination reference) of the determination reference time ta is measured by a timer (not shown) that uses the time measuring function of the CPU that constitutes the control device 10. Counting).

  In the abnormality / normality determination unit 32, the torque signal d detected by the torque sensor 3 is compared with the determination reference value da corresponding to the vehicle speed and the elapsed time (or determination reference number) of the determination reference time ta and input. Whether or not the torque signal d exceeds the determination reference value da, and if so, whether or not the state where the torque signal d exceeds the determination reference value da has passed the determination reference time ta (or the number of determination reference times) Or not) is determined.

  As a result of the determination, when the input torque signal d exceeds the determination reference value da and the exceeded state exceeds the determination reference time ta (or when the determination reference count is exceeded), the torque signal is abnormal, that is, The determination that an abnormality has occurred in the torque sensor 3 is confirmed. When it is determined that an abnormality has occurred in the torque sensor 3, an operation signal is output to the failsafe processor 33 after a predetermined time (a time for performing a plurality of normal return determinations) has elapsed. The The fail safe processor 33 operates the motor relay 34 to open the contact 34a, and the power supply to the motor 9 is cut off.

  Further, even if it is determined that the torque signal is abnormal, that is, an abnormality has occurred in the torque sensor 3, the torque signal d detected before the failsafe processor 33 operates is within the range of the determination reference value da, When it is determined that the state has passed the determination reference time ta, it is determined that the torque signal is normal, that is, the torque sensor 3 has returned to normal.

[Second Embodiment]
2nd Example is an Example which determines the abnormality of the motor which is one of the structural members which are concerned with control of a control apparatus, or a motor drive circuit. When the vehicle is stopped or running at a low speed, the handle may be turned to a large extent to enter the garage, etc., and a large torque may be generated. Since there is no possibility, if the motor or the motor drive circuit is normal, the motor current detection value becomes a small value during high speed traveling.

  FIG. 7 is a diagram for explaining a determination reference value in a conventional motor current detection value normal / abnormal determination method. The horizontal axis represents the vehicle speed V, and the vertical axis represents the motor current detection value i and the determination reference value ia. As shown in FIG. 7, when the conventional determination reference value ia is set to a constant value regardless of the vehicle speed, and the motor current detection value i is in the abnormality determination area Da above the determination reference value ia, the motor or the motor drive circuit. Was determined to be abnormal. Although not shown here, a detection margin m (allowable error range) is set to the determination reference value ia to prevent erroneous detection.

  FIG. 8 is a diagram for explaining an example of the setting of the determination reference value ia for determining the motor current detection value i indicating normality / abnormality of the motor or the motor drive circuit of the second embodiment. Are the motor detection current value i and the judgment reference value ia. The normal / abnormal determination area is divided into a plurality of areas according to the vehicle speed. The first determination area D1 is used when the vehicle speed is from zero to the vehicle speed SP1, and the second determination area D2 is used when the vehicle speed is SP1 or higher. In the low speed region D1 where the vehicle speed is from zero to the vehicle speed SP1, the motor current detection value i may increase corresponding to a large torque. Therefore, in the low speed region D1, the determination reference value ia is set to a constant value ia1 regardless of the vehicle speed. In the high speed region D2, the judgment reference value ia2 is set so as to decrease corresponding to the increase in the vehicle speed. As a result, the determination of the abnormal state can be performed more quickly and more accurately than when a constant value is set regardless of the conventional vehicle speed.

  In the second embodiment described above, it is determined that an abnormality has occurred when the motor current detection value i exceeds the determination reference value ia and the determination reference value ia exceeds a predetermined determination reference time ta. In FIG. 8, the determination reference time ta is shown together with the determination reference value ia (the vertical axis on the right side in FIG. 8). As in the case of the first embodiment, the determination reference time ta is set to a different time according to the vehicle speed, similarly to the determination reference value ia. For example, the judgment reference time ta1 is set in the low speed region D1, and the judgment reference time ta2 is set in the high speed region D2.

  In the second embodiment described above, the determination reference value ia for abnormality determination of the motor current detection value i is a vehicle speed sensitive type. However, the determination reference value ia remains constant and the determination reference time ta is the vehicle speed sensitive type. It is good. In this case, it is preferable to set a constant value regardless of the vehicle speed in the low speed region, and to set the determination reference time ta short in response to the increase in the vehicle speed in the high speed region. Further, both the determination reference value ia and the determination reference time ta for abnormality determination may be a vehicle speed sensitive type.

  Further, the determination reference value ia and the determination reference time ta may be set in advance in a look-up table format according to the vehicle speed and referred to when performing abnormality determination. In addition, a basic judgment reference value and a basic judgment reference time are set in advance, and a judgment is made by multiplying the basic judgment reference value and the basic judgment reference time by a coefficient set in advance according to the vehicle speed when the abnormality judgment is performed. The reference value ia and the determination reference time ta may be calculated.

  With reference to FIG. 2, the configuration and operation for detecting a failure of the motor drive circuit 41, which is one of the components constituting the electric power steering apparatus of the second embodiment, and performing fail-safe processing based on the detection result will be described. To do.

  The reference determination information storage unit 35 stores the above-described determination reference value ia and determination reference time ta as preset reference determination information, and a vehicle speed signal detected by the vehicle speed sensor 12 is input. Then, the determination reference value ia and the determination reference time ta according to the vehicle speed are output to the abnormality / normality determination unit 32 described later.

  The operating state information detection unit 31 receives the motor current detection value i detected by the motor current detection circuit 42 and outputs it to the abnormality / normality determination unit 32.

  The abnormality / normality determination unit 32 receives the motor current detection value i output from the operation state information detection unit 31, the determination reference value ia and the determination reference time ta output from the storage unit 35, and the determination reference time. In order to determine the elapsed time of ta, the elapsed time of the determination reference time ta is started by a timer (not shown) using the time measuring function of the CPU constituting the control device 10.

  In the abnormality / normality determination unit 32, the motor current detection value i detected by the motor current detection circuit 42 is compared with the elapsed time of the determination reference value ia and the determination reference time ta according to the vehicle speed, and the input motor current It is determined whether or not the detected value i exceeds the determination reference value ida, and if so, whether or not the motor current detection value i exceeds the determination reference value ia has passed the determination reference time ta. The

  As a result of the determination, if the input motor current detection value i exceeds the determination reference value ia and the exceeded state exceeds the determination reference time ta, the motor current detection value is abnormal, that is, the motor or the motor drive circuit 41. It is determined that an abnormality has occurred. When it is determined that an abnormality has occurred in the motor or the motor drive circuit 41, an operation signal is output to the failsafe processor 33 after a predetermined time (time for performing a plurality of normal return determinations) has elapsed. The The fail safe processor 33 operates the motor relay 34 to open the contact 34a, and the power supply to the motor 9 is cut off.

  Further, even if it is determined that an abnormality has occurred in the motor or the motor drive circuit 41, the motor current detection value i detected before the fail safe processor 33 operates is within the range of the determination reference value ia. When it is determined that the state has passed the determination reference time ta, it is determined that the detected motor current value is normal, that is, the motor or the motor drive circuit has returned to normal.

[Third embodiment]
The control device having an abnormality determination function includes a fail-safe device that stops the steering assist of the electric power steering device when an abnormality is detected. In this case, a function that prevents erroneous detection of an abnormal state ( Hereinafter, a mask function is provided. The mask function here means that the abnormality determination function executed by the abnormality / normality determination unit of the control device is stopped until a predetermined time elapses after the motor angular velocity φ becomes equal to or higher than a predetermined value. This is a function to prevent detection.

  For example, a large torque is generated in the case of turning the steering wheel large, such as in a garage, but when a large motor current value is detected, the motor angular velocity is large and the back electromotive voltage becomes an error. If it is determined, a false detection will occur. Therefore, a mask function is set in the abnormality / normality determination unit, and the abnormality determination function of the abnormality / normality determination unit is stopped until a predetermined time has elapsed after the handle is largely turned and the motor angular velocity exceeds a predetermined value. It tries to prevent detection.

  Further, the condition for setting the mask function, that is, the condition for stopping the abnormality determination function of the abnormality / normality determination unit is as described above until the predetermined time t elapses after the motor angular velocity φ becomes equal to or higher than the predetermined value. However, this condition is changed according to the vehicle speed V, and the set value of the motor angular speed φ is decreased as the speed increases, and the elapsed time t is shortened. This is because an operation that greatly turns the steering wheel during high-speed traveling is generally not possible. This makes it possible to determine the abnormal state more quickly than in the past.

  FIG. 9 is a diagram for explaining the determination reference motor angular velocity φm and the determination reference time tm that are determination reference values for the mask function, where the horizontal axis is the vehicle speed, and the vertical axis is the determination reference motor angular velocity φm that is the determination reference value for the mask function. And the determination reference time tm. The determination reference motor angular velocity φm and the determination reference time tm corresponding to the vehicle speed V shown in FIG. 9 are stored in the reference determination information storage unit 35 in the form of a lookup table or the like.

  With reference to FIG. 2, the setting and operation of the mask function for the abnormality / normality determination unit 32 of the electric power steering apparatus of the third embodiment will be described. Here, an example in which an abnormality of the motor drive circuit 41 is detected will be described, but the same applies to other components such as a torque sensor.

  The reference determination information storage unit 35 stores a determination reference motor angular speed φm and a determination reference time tm corresponding to the vehicle speed V, which is the determination reference value of the mask function described with reference to FIG.

  The operating state information detection unit 31 receives the motor current detection value i detected by the motor current detection circuit 42 and the motor angular velocity detection value φ detected by the motor angular velocity sensor 30 and outputs them to the abnormality / normality determination unit 32. The

  When the vehicle speed V detected by the vehicle speed sensor 12 is input to the reference determination information storage unit 35, the determination reference motor angular speed φm and the determination reference time tm, which are determination reference values of the mask function corresponding to the detected vehicle speed, are abnormal / The data is output to the normality determination unit 32.

  The abnormality / normality determination unit 32 receives the determination reference motor angular velocity φm output from the reference determination information storage unit 35 and the determination reference time tm, and uses a timer (not shown) that uses the time measuring function of the CPU constituting the control device 10. Thus, the measurement of the determination reference time tm is started. Further, the mask function described above is set based on the determination reference motor angular velocity φm and the determination reference time tm.

  In the abnormality / normality determination unit 32, the motor current detection value i output from the operation state information detection unit 31 and the motor angular velocity detection value φ are input. Whether or not the motor current detection value i exceeds the determination reference value ia (see the second embodiment), and if necessary, the state where the motor current detection value i exceeds the determination reference value ia is determined by the determination reference time ta. It is determined whether or not the time has passed.

  At this time, since the mask function is set in the abnormality / normality determination unit 32, until the detected motor angular velocity φ is equal to or higher than the determination reference motor angular velocity φm and a predetermined determination reference time tm of the mask function elapses, Even when the abnormality / normality determination unit 32 determines that there is an abnormality, a signal indicating the occurrence of abnormality is not output, and the failsafe processor 33 does not operate.

  When the condition of the mask function set in the abnormality / normality determination unit 32 is cleared, that is, after the detected motor angular velocity φ is equal to or greater than the determination reference value φm and the predetermined determination reference time tm has elapsed, the abnormality / normality determination unit If it is determined at 32 that an abnormality has occurred, an operation signal is output to the fail safe processor 33, the fail safe processor 33 operates the motor relay 34 to open the contact 34 a, and the motor 9 is supplied with power. Blocked.

  In the first to third embodiments described above, when an abnormality in the operation state information of the component member is detected, the steering assist of the electric power steering device is stopped by the fail-safe function. Instead of the state information, the control may be continued based on a predetermined initial value.

  A vehicle equipped with a determination means for comparing operation state information of various constituent members involved in control of the control device with predetermined determination reference information and determining abnormality determination of various component members and normal return after the abnormality determination. In the electric power steering apparatus, it is possible to quickly determine the abnormality of various components and return to normal after the abnormality determination without causing the driver to feel uncomfortable when operating the steering wheel.

The figure explaining the outline of a structure of an electric power steering apparatus. The block diagram of the control apparatus of the Example of this invention. The block diagram which shows an example of a structure of a motor drive circuit. The figure explaining the relationship between the steering torque required when a steering handle is steered only a predetermined angle, and a vehicle speed. The figure explaining the determination reference value set with the abnormality determination method of the conventional steering torque detection value. The figure explaining the setting of the determination reference value which performs abnormality determination of the steering torque detection value of 1st Example. The figure explaining the determination reference value set with the abnormality determination method of the conventional motor current detection value. The figure explaining the judgment reference value which judges abnormality of the motor current detection value of the 2nd example. The figure explaining the determination reference value and determination reference time of the mask function of 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Axis 3 Torque sensor 4 Reduction gear 5a, 5b Universal joint 7 Pinion rack mechanism 8 Tie rod 9 Motor 10 Control device 11 Ignition key 12 Vehicle speed sensor 14 Battery 21 Phase compensator 22 Current command value calculator 23 Comparison 24 Differential Compensator 25 Proportional Calculator 26 Integral Calculator 27 Adder 30 Motor Angular Velocity Sensor 31 Operating State Information Detection Unit 32 Abnormal / Normal Determination Unit 33 Fail-Safe Processing Unit 34 Motor Relay 35 Reference Determination Information Storage Unit 41 Motor Drive Circuit 42 Motor current detection circuit

Claims (3)

In an electric power steering apparatus for a vehicle including a steering mechanism having a motor that applies a steering assist force to the steering mechanism of the vehicle,
A control device for controlling the motor;
A torque sensor provided on the steering handle shaft of the steering mechanism for detecting torque generated in the shaft;
Equipped with a vehicle speed sensor,
The controller is
A motor drive circuit;
A motor current detection circuit;
An operating state information detector;
A reference determination information storage unit;
An abnormality / normality determination unit;
A fail-safe processing unit;
Equipped with a motor relay,
The operating state information detection unit inputs a steering torque detection value detected by the torque sensor, and outputs the steering torque detection value to the abnormality / normality determination unit.
In the reference determination information storage unit, a plurality of torque determination reference values and determination reference times corresponding to a plurality of vehicle speed regions are stored in advance.
The abnormality / normality determination unit inputs the steering torque detection value output from the operation state information detection unit, the torque determination reference value and the determination reference time corresponding to the vehicle speed region output from the reference determination information storage unit Then, the torque detection signal detected by the torque sensor is compared with the torque determination reference value according to the vehicle speed, the torque detection signal exceeds the determination reference value, and the exceeded state exceeds the determination reference time. When it is determined that an abnormality has occurred in the torque sensor, an operation signal for cutting off the power supply to the motor is output to the fail safe processing unit,
An abnormality occurs in the torque sensor, and the steering torque detection value is within the range of the determination reference value before the determination reference time elapses until the fail safe processing unit outputs an operation signal for interrupting power supply to the motor. And when it is determined that the state has exceeded the determination reference time, it is determined that the torque sensor has returned to normal . In an electric power steering apparatus for a vehicle including a steering mechanism having a motor that applies a steering assist force to the steering mechanism of the vehicle,
A control device for controlling the motor;
A torque sensor provided on the steering handle shaft of the steering mechanism for detecting torque generated in the shaft;
Equipped with a vehicle speed sensor,
The controller is
A motor drive circuit;
A motor current detection circuit;
An operating state information detector;
A reference determination information storage unit;
An abnormality / normality determination unit;
A fail-safe processing unit;
Equipped with a motor relay,
The operation state information detection unit inputs a motor current detection value detected by the motor current detection circuit, and outputs this to the abnormality / normality determination unit,
In the reference determination information storage unit, a plurality of motor current determination reference values and determination reference times corresponding to a plurality of vehicle speed regions are stored in advance.
The abnormality / normality determination unit includes a motor current detection value output from the operation state information detection unit, a motor current determination reference value and a determination reference time according to a vehicle speed region output from the reference determination information storage unit. The motor current detection value detected by the motor current detection circuit is compared with a motor current determination reference value corresponding to the vehicle speed, and the motor current detection value exceeds the determination reference value, When the determination reference time is exceeded, it is determined that an abnormality has occurred in the motor or the motor drive circuit, and an operation signal for cutting off power supply to the motor is output to the fail safe processing unit,
An abnormality occurs in the motor or the motor drive circuit, and the motor current detection value is set to the determination reference before the determination reference time elapses until the fail safe processing unit outputs an operation signal for cutting off power supply to the motor. in the range of values, the motor or the motor driving circuit is normally returned to the judged dynamic power collector you characterized in that steering when it is determined that the condition has passed beyond the determination reference time apparatus. In an electric power steering apparatus for a vehicle including a steering mechanism having a motor that applies a steering assist force to the steering mechanism of the vehicle,
A control device for controlling the motor;
A torque sensor provided on the steering handle shaft of the steering mechanism for detecting torque generated in the shaft;
A vehicle speed sensor,
A motor angular velocity sensor for detecting the angular velocity of the motor;
The controller is
A motor drive circuit;
A motor current detection circuit;
A motor angular velocity sensor;
An operating state information detector;
A reference determination information storage unit;
An abnormality / normality determination unit;
A fail-safe processing unit;
Equipped with a motor relay,
The operation state information detection unit inputs a motor angular velocity detection value detected by the motor angular velocity sensor, and outputs this to the abnormality / normality determination unit,
In the reference determination information storage unit, a plurality of determination reference motor angular velocities and determination reference times corresponding to a plurality of vehicle speed regions are stored in advance, and are detected when the vehicle speed detected by the vehicle speed sensor is input. The determination reference motor angular velocity and the determination reference time according to the vehicle speed are output to the abnormality / normality determination unit,
The abnormality / normality determination unit inputs the determination reference motor angular velocity and the determination reference time corresponding to the vehicle speed region output from the reference determination information storage unit, and outputs the motor output from the operation state information detection unit. An angular velocity detection value is compared with the determination reference motor angular velocity detection value, and whether the motor angular velocity detection value exceeds the determination reference motor angular velocity or not is determined when the motor angular velocity detection value exceeds the determination reference value. Determine whether the reference time has passed or not,
The abnormality / normality determination unit does not output a signal indicating abnormality determination until a predetermined time has elapsed after the determination reference time when the motor angular velocity detection value exceeds the determination reference value, and after the determination reference time has elapsed. If the detected value of the motor angular velocity detected by the motor angular velocity sensor is equal to or greater than the determination reference value and a predetermined determination reference time has elapsed and the abnormality / normality determination unit determines that an abnormality has occurred, the fail-safe processing unit The electric power steering apparatus according to claim 1 or 2, wherein an operation signal for cutting off power supply to the motor is output .

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