JP2010137774A - Electric power-steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power-steering device surely notifying an operator of abnormality in detecting the abnormality. <P>SOLUTION: The electric power-steering device includes a 3-phase brushless motor 12 imparting a steering assistance force reducing the steering load of the operator in a steering system, and generates an alarm signal utilizing at least either of the sense of hearing and the sense of touching to the operator responding to at least either of a running condition detected by a running condition detecting means and a steering condition detected by a steering condition detecting means in detecting abnormality of a system. Also, its alarm signal level is determined dynamically responding to at least either of the running condition and the steering condition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that includes a steering assist mechanism having an electric motor that applies a steering assist force to a steering system, and that notifies a driver when an abnormality is detected.

As a conventional electric power steering device, when a system abnormality is detected, vibration is applied to the steering wheel in parallel with abnormality notification using at least one of the visual and auditory senses, and the steering assist force is gradually applied after the vibration is applied to the steering wheel. It is known that it is reduced (see, for example, Patent Document 1).
No. 2575522

  However, in the electric power steering device described in Patent Document 1, vibration is generated in the steering wheel without considering the traveling state and steering state at the time of occurrence of an abnormality, so in some cases, the driver feels uncomfortable. There is a risk of giving. For example, when a large vibration is generated during high-speed driving, a very large stress is given to the driver, and there is a possibility that the running stability is adversely affected due to the abnormality notification.

Further, in the electric power steering device described in Patent Document 1, since the motor generates vibrations at a constant period, the generated vibration frequency is equivalent to the vibration frequency transmitted to the steering by the road surface reaction force. In such a case, it is impossible to reliably notify the abnormality.
Therefore, an object of the present invention is to provide an electric power steering device that reliably notifies a driver of an abnormality when an abnormality is detected.

In order to solve the above-described problem, an electric power steering apparatus according to a first aspect of the present invention includes an electric motor that applies a steering assist force that reduces a driver's steering burden to a steering system, and at least a steering assist command value based on a steering torque. And an electric power steering device comprising a control means for driving and controlling the electric motor based on the calculated steering assist command value,
A driving state detecting unit for detecting a driving state of the vehicle, a steering state detecting unit for detecting a steering state by a driver, an abnormality detecting unit for detecting an abnormality of the system, and when the abnormality is detected by the abnormality detecting unit, An informing means for generating a warning signal using at least one of hearing and tactile sensation for the driver according to at least one of the running state detected by the running state detecting means and the steering state detected by the steering state detecting means; It is characterized by having.

According to a second aspect of the present invention, there is provided the electric power steering apparatus according to the first aspect of the invention, wherein the notification means generates the warning signal by each control unit for performing the drive control.
The electric power steering apparatus according to a third aspect is the invention according to the first or second aspect, wherein the traveling state detecting means includes, as the traveling state, a vehicle speed, an engine speed, a vehicle acceleration, a yaw rate, and a road surface friction state. It is characterized by detecting at least one.

According to a fourth aspect of the present invention, there is provided the electric power steering apparatus according to any one of the first to third aspects, wherein the steering state detecting means includes a steering torque, a rotation angle of the electric motor as the steering state, It is characterized in that at least one of the steering angle and the amount of current flowing through the electric motor is detected.
Furthermore, the electric power steering apparatus according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein the informing means detects the traveling state detected by the traveling state detecting means and the steering state detecting means. According to the present invention, at least one of the type of the warning signal and the level of the warning signal is changed in accordance with at least one of the steering states detected in (1).

According to a sixth aspect of the present invention, in the electric power steering apparatus according to the fifth aspect of the invention, when the running state detected by the running state detecting unit generates a warning signal using a tactile sensation, When the vehicle behavior is highly likely to become unstable, the generation of a warning signal using the tactile sense is limited.
Furthermore, the electric power steering apparatus according to claim 7 is the invention according to claim 5 or 6, wherein the notifying means generates a warning signal using a tactile sensation when the running state detected by the running state detecting means. In addition, when the vehicle behavior is highly likely to become unstable, after generating a warning signal using hearing, the driver determines that the warning signal is not recognized for a predetermined period of time. It is characterized by generating a warning signal using the sense of touch.

An electric power steering apparatus according to an eighth aspect of the present invention is the invention according to any one of the fifth to seventh aspects, wherein the notifying means gives a steering state detected by the steering state detecting means to a steering system. The higher the steering assist force is, the higher the warning signal level is set.
Furthermore, in the electric power steering apparatus according to claim 9, in the invention according to any one of claims 5 to 8, the notification unit detects an abnormality with the abnormality detection unit and generates a warning signal. Thereafter, when the driver determines that the warning signal is unrecognized for a predetermined period, the warning signal level is gradually increased as time elapses.

  According to the electric power steering apparatus of the present invention, when a system abnormality is detected, a warning signal using at least one of hearing and tactile sensation is given to the driver according to at least one of the running state and the steering state. Because it occurs, it is possible to notify the driver of the abnormality without giving stress to the driver without giving stress to the driver by giving an appropriate abnormality notification corresponding to the driving state and steering state at the time of occurrence of the abnormality. Thus, it is possible to prevent the vehicle behavior from changing significantly and improve the running stability.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment of an electric power steering apparatus according to the present invention.
In the figure, reference numeral 1 denotes a steering wheel, and a steering force applied to the steering wheel 1 from a driver is transmitted to a steering shaft 2 having an input shaft 2a and an output shaft 2b. The steering shaft 2 has one end of the input shaft 2 a connected to the steering wheel 1 and the other end connected to one end of the output shaft 2 b via the torque sensor 3.

  The steering force transmitted to the output shaft 2 b is transmitted to the lower shaft 5 via the universal joint 4 and further transmitted to the pinion shaft 7 via the universal joint 6. The steering force transmitted to the pinion shaft 7 is transmitted to the tie rod 9 via the steering gear 8 and steers steered wheels (not shown). Here, the steering gear 8 is configured in a rack and pinion type having a pinion 8a connected to the pinion shaft 7 and a rack 8b meshing with the pinion 8a, and the rotational motion transmitted to the pinion 8a is linearly moved by the rack 8b. It has been converted to movement.

A steering assist mechanism 10 for transmitting a steering assist force to the output shaft 2b is connected to the output shaft 2b of the steering shaft 2. The steering assist mechanism 10 includes a reduction gear 11 connected to the output shaft 2b, and a three-phase brushless motor 12 as an electric motor that is connected to the reduction gear 11 and generates a steering assist force for the steering system. Yes.
The torque sensor 3 detects the steering torque that is applied to the steering wheel 1 and transmitted to the input shaft 2a. The torsional angle displacement of a torsion bar (not shown) that interposes the steering torque between the input shaft 2a and the output shaft 2b. The torsional angular displacement is detected by, for example, a potentiometer.

  Further, as shown in FIG. 2, the three-phase brushless motor 12 has a U-phase coil Lu, a V-phase coil Lv, and a W-phase coil Lw connected at one end to form a star connection, and the coils Lu, Lv, and Lw The other end is connected to the steering assist control device 20, and motor drive currents Iu, Iv, and Iw are individually supplied. In addition, the three-phase brushless motor 12 includes a rotor position detection circuit 13 including a resolver, an encoder, and the like that detect the rotational position of the rotor.

  As shown in FIG. 2, the steering assist control device 20 receives the steering torque T detected by the torque sensor 3 and the vehicle speed detection value Vs detected by the vehicle speed sensor 21 and is detected by the rotor position detection circuit 13. Is output from the motor current detection circuit 22 that detects the motor drive currents Iu, Iv, and Iw supplied to the phase coils Lu, Lv, and Lw of the three-phase brushless motor 12. Drive current detection values Iud, Ivd, and Iwd are input.

  The steering assist control device 20 calculates a steering assist target current value based on the steering torque T, the vehicle speed detection value Vs, and the motor rotation angle θ, and outputs motor voltage command values Vu, Vv, and Vw, for example. The control arithmetic device 23 configured, a motor drive circuit 24 configured by a field effect transistor (FET) that drives the three-phase brushless motor 12, and phase voltage command values Vu, Vv, and Vw output from the control arithmetic device 23. And an FET gate drive circuit 25 for controlling the gate current of the field effect transistor of the motor drive circuit 24.

  Then, the control arithmetic unit 23 determines whether or not the electric power steering system is in an abnormal state such as a state requiring repair or a reduced performance state. Normal steering assist control is performed in which a steering assist torque is applied to the steering shaft according to the steering operation of the person. On the other hand, when a state where an abnormality has occurred is detected, an abnormality notification process described later is executed to notify the driver that an abnormality has occurred in the system, and the state where the abnormality has occurred If the system continues for a certain period of time, it is determined that an abnormality has occurred in the system, and fail-safe processing such as stopping steering assist control, limiting steering assist torque, and steering assist control using a predetermined alternative torque is performed.

It should be noted that the state in which an abnormality has occurred in the system does not lead to the complete loss of the EPS function, such as abnormal output signals of various sensors, but the operation of the motor 12 is stopped or the output torque of the motor 12 is This is a state where it is desirable to provide fail-safety that restricts the above.
The abnormality notification process is executed within a period from when the abnormal state is detected until the steering assist control is stopped, such as turning off the ignition switch.

FIG. 3 is a flowchart showing an abnormality notification processing procedure executed by the control arithmetic device 23. In the abnormality notification process, first, a system abnormality determination process is performed in step S1, and the process proceeds to step S2.
In step S2, it is determined whether or not an abnormality has occurred in the system based on the determination result in step S1. When no abnormality has occurred, the abnormality notification process is terminated, and when an abnormality has occurred. The process proceeds to step S3.

In step S3, it is determined whether or not the vehicle speed Vs is equal to or higher than the vehicle speed threshold Vth. If Vs <Vth, it is determined that the vehicle is traveling at a low speed, and the process proceeds to step S13 described later, where Vs ≧ Vth. When there is a certain time, it is determined that the vehicle is traveling at a high speed, and the process proceeds to step S4.
In step S4, a warning sound which is a warning signal using hearing is generated. Here, an abnormal noise is generated from the motor 12 by intentionally shifting the setting timing of the PWM duty when controlling the energization current to the three-phase brushless motor 12 that is set to a constant period when the system is normal. This is a warning sound.

Next, in step S5, it is determined whether or not the vehicle has decelerated after the warning sound is generated, and when the vehicle is detected to decelerate, the driver recognizes the abnormality notification by the warning sound and safety measures for the abnormality are taken. The process proceeds to step S6, the generation of the warning signal is stopped, and the abnormality notification process is terminated. On the other hand, when deceleration of the vehicle is not detected, it is determined whether or not a predetermined time T1 has elapsed since the transition to step S7 and the warning sound was generated. Then, the vehicle deceleration is monitored until the predetermined time T1 elapses, and when the predetermined time T1 elapses when the vehicle is not decelerated, the process proceeds to step S8.
In step S8, a warning sound of the second stage is generated by changing the warning sound level (frequency band of the warning sound) according to the elapsed time since the warning sound was generated. Here, the warning sound level is changed by changing the setting timing cycle of the PWM duty.

FIG. 4 is obtained by connecting the values of the sound pressure levels having the same sound volume for each frequency of the pure sound, and is called an equal loudness curve of the sound volume.
The equal loudness curve is created based on the average value of measurements from a large number of people, and the horizontal axis represents frequency [Hz] and the vertical axis represents sound pressure level [dB]. All the sounds on the same curve have the same volume, and the volume level (in units of phon) described in each curve matches the dB value at 1000 Hz.

For example, looking at the curve A marked 40 phon, the value of the sound pressure level on the vertical axis is 40 [dB], which is the same as the value of phon, at 1000 Hz on the horizontal axis (point a). And at 250 Hz of this curve, the sound pressure level is about 50 dB (point b). This means that a pure tone of 1000 Hz at 40 dB sounds as loud as a pure tone of 50 Hz at 50 dB.
Looking at these curves, the greater the level, the flatter the frequency characteristics, but at a lower level, the bass curve is raised and the ears feel dull, and human hearing is 4000 Hz. You can see the sharpest things around. Note that the lowest curve is the curve of the minimum audible value.

That is, by increasing the frequency of the warning sound, it becomes easier to hear the warning sound. In the present embodiment, the warning sound level is set according to the elapsed time with reference to the warning sound frequency calculation map shown in FIG. This warning sound frequency calculation map takes the elapsed time T [sec] after the second-stage warning sound is generated on the horizontal axis, the warning sound frequency f [Hz] on the vertical axis, and the elapsed time T is a predetermined time Ts. As the elapsed time T increases, the warning sound frequency is proportionally increased from f = 30 Hz to f = 4000 Hz, and the elapsed time T is set to the predetermined time Ts. Thereafter, it is set to be fixed at f = 4000 Hz.
As described above, after detecting the system abnormality and generating the first stage warning sound, when it is determined that the driver has not recognized the warning sound for a predetermined period of time, the second stage warning sound is A warning sound whose warning sound level gradually increases with the passage of time is generated.

  Next, the process proceeds to step S9, where it is determined whether or not the vehicle has decelerated after the second-stage warning sound is generated. When the vehicle is decelerated, the driver recognizes an abnormality notification by the warning sound. Then, it is determined that safety measures for the abnormality have been taken, and the process proceeds to step S6. On the other hand, when deceleration of the vehicle is not detected, it is determined whether or not a predetermined time T2 has elapsed since the transition to Step S10 and the second-stage warning sound is generated. Then, the deceleration of the vehicle is monitored until the predetermined time T2 elapses, and the process proceeds to step S11 when the predetermined time T2 elapses when the vehicle does not decelerate.

  In step S11, vibration is generated for the steering system, which is a warning signal using the sense of touch. Usually, the detected current value includes an offset amount of hardware with respect to the actual motor energization current, and control is performed to correct a portion where linearity is not compensated. Therefore, vibration is generated in the steering system by setting the energization current correction value to a value different from the normal value (for example, a value in accordance with the maximum correction value variation product characteristics). In this case, the handle vibration level can be changed by changing the magnitude of the energization current correction value.

  When a three-phase brushless motor is applied as an electric motor as in this embodiment, an offset is intentionally given to two phase currents. At this time, if the current detector is for two phases, the estimated value is used for the remaining one phase, so it can be left as it is. However, if all three phases can be detected, the two phases are assigned the same sign. Offset is performed so that the remaining one phase is offset to the opposite sign.

  In addition, the magnitude of the vibration generated here is large in proportion to the steering assist amount because the possibility that the vehicle behavior is greatly changed even if a certain amount of vibration is generated is small when the steering assist amount is large. Set to. The magnitude of the vibration is set according to the elapsed time after the vibration is generated, is set to a relatively small vibration at the initial stage, and is changed to a large vibration as time elapses. However, this vibration should be stopped to such an extent that the vehicle yaw rate is not significantly changed.

  Furthermore, the frequency of the vibration generated here is set to a frequency different from the vibration frequency of the road surface reaction force. When performing this measure, for example, when the steering torque signal is normally detected, the steering wheel signal is generated at a frequency other than the vibration frequency component detected as the steering torque signal. If an abnormality has occurred in the torque system and the steering torque signal cannot be normally detected, the vibration frequency due to the road surface reaction force is determined from the motor speed information, and the handle vibration frequency is determined. Good.

  Next, the process proceeds to step S12, where it is determined whether or not the vehicle has decelerated after vibration is generated in the steering system. When the vehicle decelerates is detected, the driver recognizes an abnormality notification due to warning vibration. Then, it is determined that safety measures for the abnormality have been taken, and the process proceeds to step S6. On the other hand, when the deceleration of the vehicle is not detected, the process proceeds to step S11.

  As described above, when the vehicle is traveling at high speed, it is determined that the vehicle behavior is likely to become unstable when a warning signal (handle vibration) using a tactile sensation is generated, and the steering wheel vibration is detected. First, only a warning signal (warning sound) using hearing is generated. Then, after the warning sound is generated, it is determined that the driver has not recognized this for a predetermined period, and then the handle vibration is generated.

  Further, when the vehicle is traveling at a low speed, the process proceeds from step S2 to step S13, and in step S13, vibration is generated for the steering system, which is a warning signal using tactile sensation. The magnitude of the steering wheel vibration is set to increase in proportion to the steering assist amount as described above. Therefore, in this low-speed traveling state, the magnitude of vibration generated in the initial stage is set to be larger than the magnitude of vibration generated in the initial stage of high-speed traveling state.

Next, the process proceeds to step S14 to generate a warning sound that is a warning signal using hearing, and the process proceeds to step S15.
As described above, in the low-speed traveling state, the steering system is vibrated while generating a warning sound.
In step S15, it is determined whether or not the vehicle has decelerated after each warning signal is generated. When the vehicle is decelerated, the driver recognizes an abnormality notification by each warning signal, and safety measures for the abnormality are taken. If it is determined that it has been taken, the process proceeds to step S6. On the other hand, when deceleration of the vehicle is not detected, the process proceeds to step S16 to determine whether or not a predetermined time T3 has elapsed since each warning signal was generated. The vehicle is monitored for deceleration until the predetermined time T3 elapses, and when the predetermined time T3 elapses when the vehicle is not decelerated, the process proceeds to step S17.

In step S17, the warning vibration level is changed according to the elapsed time, and the process proceeds to step S18. The warning sound level is changed according to the elapsed time, and the process proceeds to step S19.
In step S19, it is determined whether or not the vehicle has decelerated after changing the level of each warning signal. When the vehicle is decelerated, the driver recognizes an abnormality notification by each warning signal, and safety for the abnormality is detected. It is determined that a measure has been taken and the process proceeds to step S6. On the other hand, when the deceleration of the vehicle is not detected, the process proceeds to step S17.
1 and 2, the torque sensor 3, the rotor one detection circuit 13, and the motor current detection circuit 22 correspond to the steering state detection means, and the vehicle speed sensor 21 corresponds to the running state detection means. In FIG. 3, step S1 corresponds to the abnormality detection means, and steps S3 to S19 correspond to the notification means.

Next, the operation and effect of this embodiment will be described.
Assuming that the ignition switch is turned on in order to start traveling of the vehicle, the steering assist control device 20 is powered on and the steering arithmetic device 23 starts executing the steering assist control process. At this time, if it is assumed that no abnormality has occurred in the system, it is determined No in step S2 in the abnormality notification process of FIG. 3, so that an alarm signal for abnormality notification is not issued to the driver. The process ends. Thereby, the control calculation device 23 calculates the steering assist target current value based on the steering torque T and the vehicle speed Vs, and outputs motor voltage command values Vu, Vv, and Vw.

When the vehicle is stopped and the steering wheel 1 is not steered, the steering torque T detected by the torque sensor 3 is “0”, and the vehicle speed Vs detected by the vehicle speed sensor 21 is also “0”. Therefore, the steering assist target current value is also “0”. Therefore, the three-phase brushless motor 12 continues to be stopped.
When the vehicle starts from this state, a steering assist target current value corresponding to the vehicle speed Vs is calculated, and based on this, the three-phase brushless motor 12 is driven and controlled. As a result, steering assist torque corresponding to the vehicle speed Vs is generated and transmitted to the output shaft 2b of the steering shaft 2 via the reduction gear 11, so that the driver's steering burden can be reduced.

  Then, if an abnormality occurs in the system when the vehicle is in a low-speed traveling state where V <Vth, in the abnormality notification process of FIG. 3, it is determined Yes in step S2, and the process proceeds to step S3, and No is determined in step S3. Then, the process proceeds to step S13. Then, a handle vibration that is a warning signal using a tactile sensation is generated, and a warning sound that is a warning signal using hearing is generated in step S14.

This handle vibration is generated by intentionally shifting the correction value for the detected current value of the motor energization current. The frequency of the handle vibration is set to a frequency different from the vibration frequency component due to the road surface reaction force. As a result, it is possible to reliably avoid a situation in which the driver cannot determine whether the generated steering wheel vibration is vibration due to road surface reaction force or vibration for abnormality notification.
The warning sound is generated by intentionally shifting the setting timing of the PWM duty when the energization current of the three-phase brushless motor 12 is controlled.

  By the way, there is an electric power steering apparatus that separately generates a warning sound and thereby generates a warning sound, but in the case of a configuration that generates a warning sound via a device other than the electric power steering apparatus in this way, the warning sound is generated. In addition to increasing the cost of providing a dedicated device for generating the alarm, if the communication path with the device generating the alarm is interrupted, the alarm cannot be generated.

On the other hand, in this embodiment, since the warning sound is generated using the three-phase brushless motor 12 (device provided for steering assist control), a dedicated device for generating the warning sound is not provided. It is possible to notify the driver of system abnormality.
When the driver recognizes the abnormal state of the system and decelerates the vehicle due to the generation of the handle vibration and the warning sound, it determines Yes in step S15 and proceeds to step S6 to stop the generation of the handle vibration and the warning sound. Then, the abnormality notification process ends.

On the other hand, if an abnormality occurs in the system when the vehicle is in a high-speed traveling state of V ≧ Vth, the abnormality notification process in FIG. 3 is determined to be Yes in step S2 and proceeds to step S3, and determined as Yes in step S3. Then, the process proceeds to step S4. First, a warning sound, which is a warning signal using hearing, is generated as an abnormality notification in the initial stage.
In general, almost no steering assist force is required during high-speed driving, so generating a large steering wheel vibration as a warning signal for notifying the occurrence of an abnormality in this state is a factor that significantly changes the vehicle behavior. It becomes. Therefore, when the vehicle is traveling at a high speed, first, abnormality notification is performed only with a warning sound. As a result, it is possible to prevent the driver from being greatly stressed and to prevent the driver from making a steering error due to the abnormality notification.

At this time, if the state in which the driver does not notice the warning sound continues for a predetermined time T1 due to, for example, listening to music at a loud volume in the passenger compartment, No is determined in step S5, and Yes is determined in step S7. The warning sound level is changed as a two-stage abnormality notification. After that, the warning sound gradually changes to a frequency band that is more audible as time passes.
If the driver does not notice the warning sound and does not take safety measures such as decelerating the vehicle even after a predetermined time T2 has elapsed since the start of the second-stage abnormality notification, the process proceeds from step S10 to step S11. As a third-stage abnormality notification, a handle vibration is generated in addition to the warning sound.

Thus, when the driver recognizes an abnormality in the system and decelerates the vehicle, the process proceeds from step S12 to step S6, the generation of the steering wheel vibration and the warning sound is stopped, and the abnormality notification process is terminated.
As mentioned above, even if a warning occurs due to an abnormality in the system, if the driver does not notice it and safety measures such as decelerating the vehicle cannot be taken, the level of the warning signal is changed. Thus, the driver can surely recognize the abnormality of the system, and it is possible to prevent the driver from falling into a situation unintended by the driver due to the occurrence of the abnormality.

  Thus, in the above embodiment, when a system abnormality is detected, a warning signal using at least one of hearing and touch is generated for the driver according to at least one of the running state and the steering state. Appropriate abnormality notifications commensurate with the driving state and steering state at the time of abnormality occurrence can be made to ensure that the abnormality occurrence is recognized without giving stress to the driver, and a significant vehicle resulting from the abnormality notification A change in behavior can be prevented to improve running stability.

  In addition, a warning sound is generated by intentionally shifting the PWM duty setting timing when controlling the energization current to the electric motor, or the handle vibration is changed by changing the correction value for the current detection value of the motor energization current. Since a warning signal is generated using a control unit (or device) for performing steering assist control, such as generating a warning signal, it is not necessary to separately provide a dedicated device for generating a warning signal, thereby reducing costs. it can. In addition, unlike the case where a dedicated device is provided, a situation in which an abnormality occurs in the communication path and a warning signal cannot be generated does not occur, so stable abnormality notification can be performed.

Furthermore, since at least one of the vehicle speed, the engine speed, the vehicle acceleration, the yaw rate, and the road surface friction condition is detected as the running state, the influence on the vehicle behavior due to the generation of the warning signal is taken into consideration and the driving state is met. Appropriate abnormality notification can be performed.
Further, since at least one of the steering torque, the rotation angle of the electric motor, the steering angle, and the energization current amount of the electric motor is detected as the steering state, an appropriate abnormality notification corresponding to the generation state of the steering assist force is performed. In addition, since the steering state is detected using information necessary for performing the steering assist control, it is not necessary to separately provide a sensor or the like for detecting the steering state, and the cost can be reduced.

Furthermore, since the type of warning signal or the level of the warning signal is changed according to at least one of the driving state and the steering state, it depends on the driving state of the vehicle, the steering state by the driver, and the generation state of the steering assist force. Under any circumstances, it is possible to reliably notify the abnormality within a range that does not give the driver a sense of incongruity.
Also, a warning signal using tactile sensation when there is a high possibility that the vehicle behavior will become unstable when the driving state detects an abnormality and generates a warning signal (handle vibration) using tactile sensation. Since the occurrence of (handle vibration) is limited, for example, when the vehicle is traveling at high speed, generating a warning signal (handle vibration) using tactile sensation adversely affects the driver's steering and Even under circumstances where there is a possibility of significant changes, it is possible to notify the driver of abnormality while ensuring traveling stability.

  Furthermore, when the driving condition is a driving condition where the vehicle behavior is likely to become unstable when an abnormality is detected and a warning signal (handle vibration) using tactile sensation is generated, a warning signal using hearing (Warning sound) is generated, a warning signal (handle vibration) using tactile sensation is generated after it is determined that the driver has not recognized the warning signal for a predetermined period of time. Even if the driver listens to music at a loud volume in the passenger compartment and the driver does not notice the warning sound, the driver can be surely recognized that the abnormality has occurred. .

  Further, when the steering state is a steering state where it is necessary to apply a large steering assist force to the steering system, the warning signal level is set to be larger as the required steering assist force is larger. When a large warning signal (steering wheel vibration) generates a large impact on the vehicle behavior, such as when driving with a steering torque + α by the driver, the warning signal level is reduced. Abnormality notification can be appropriately performed according to the occurrence state.

Furthermore, after the abnormality is detected and a warning signal is generated, when the vehicle deceleration is not detected for a predetermined period, the warning signal is gradually increased as time elapses. The occurrence can be recognized.
In the above-described embodiment, a case has been described in which a handle vibration is generated in addition to the warning sound after a predetermined time has elapsed from the generation of the warning sound during high-speed driving, but a minute handle vibration is generated together with the warning sound when an abnormality occurs. Alternatively, the warning sound may be switched to the handle vibration alone after a predetermined time has elapsed from the generation of the warning sound.

  In the above embodiment, the case where the warning sound is generated by intentionally shifting the setting timing of the PWM duty ratio when controlling the energization current of the electric motor has been described. A warning sound or steering wheel vibration may be generated by repeatedly setting the ratio to a fixed value or a normal value at high speed. In this case, for example, in the case of a system in which the PWM duty is set every 100 μS, a warning sound and a handle vibration can be generated by setting a duty other than the duty calculated by the current controller. At this time, by changing the section in which a value other than the calculated duty is set, the range of the warning sound and the degree of vibration can be changed.

Note that values other than the calculated duty may be arbitrary, but in the case of a multiphase motor such as a brushless motor, if the electromagnetic brake state is established by setting all phase duty to a fixed value, the unintended handle The rotation can be prevented, and the vehicle yaw rate can be prevented from changing greatly.
Furthermore, a warning sound may be generated by intentionally shifting the timing of detecting the electric motor energization current, and furthermore, the ideal electric characteristic parameters of the electric motor may be varied within a range where the system does not fail. May generate a warning sound.

  Furthermore, in the case where the motor is laid out at a place away from the driver's seat, such as R & P type EPS and ball screw type EPS, the steering assist control device 20 is laid out in the passenger compartment and has a mechanical contact, When a relay or a switch that generates sound when the contact is opened or closed is mounted, the steering assist control device 20 itself can be operated by intentionally performing the opening and closing operation of the contact at a constant cycle or an indefinite cycle. It is also possible to generate a warning sound for anomaly notification. Thereby, it is possible to make the driver recognize the warning sound reliably regardless of the configuration of the EPS.

  Further, the frequency of the sound generated from the three-phase brushless motor 12 can be made equal to the natural vibration frequency of the steering machine system. As a result, when the motor is laid out at a location away from the driver's seat, such as R & P type EPS or ball screw type EPS, or when the steering assist control device 20 is laid out at a location away from the passenger compartment, etc. Even if it is difficult to transmit to the driver even if sound is generated, by performing assist control so that the motor vibrates in the natural vibration frequency band of the mechanical system, sound is reliably transmitted to the vehicle interior via the steering mechanism. Can be transmitted.

Further, the engine speed can be monitored, and the frequency of the sound generated from the three-phase brushless motor 12 can be set to a frequency range different from the engine sound at the engine speed. As a result, it is possible to reliably avoid a situation in which the driver cannot determine whether the generated sound is an engine sound or a warning sound for abnormality notification.
In the above embodiment, the case where the warning signal is generated according to at least one of the traveling state and the steering state at the time of occurrence of the abnormality has been described. However, the change in the vehicle behavior while the warning signal is being generated is monitored. However, the warning signal level can also be adjusted to such an extent that a large vehicle behavior change does not occur.

  For example, when steering wheel vibration is generated as a warning signal, road surface friction information obtained from a road surface friction force sensor, yaw rate obtained from a yaw rate sensor, vehicle acceleration obtained from an acceleration sensor, engine speed sensor, etc. Based on the obtained engine speed, the steering wheel vibration level can be determined while monitoring so that the vehicle behavior does not become unstable along with the abnormality notification. As a result, for example, when the road friction force is low even during low-speed traveling, it is possible to notify the driver of abnormality while improving traveling stability, such as limiting the generation of steering wheel vibration.

  Furthermore, in the above-described embodiment, the case where the handle vibration is generated by intentionally shifting the offset value when correcting the current detection value of the motor energization current has been described. However, when the current detection value is corrected Handle vibration can also be generated by intentionally shifting the gain correction value for each phase. In this case, by shifting the gain, the vibration is increased in proportion to the steering assist amount, for example, a slight vibration is generated when the amount of current supplied to the motor is small, and a large vibration is generated as the amount of current supplied is increased. be able to.

  Further, by intentionally adding an offset of several degrees to the motor rotation angle θ detected by the rotor position detection circuit 13, it is possible to generate a handle vibration or a warning sound. In this case, the amount of angle to be shifted is the same, and offset addition is performed to invert the sign at a predetermined cycle. At this time, the warning signal level can be changed according to the amount of the offset value and the cycle of adding the offset value.

Furthermore, the steering assisting control can be used to make the steering easier to self-oscillate by intentionally changing the gain of the feedforward value (center response improvement command value) to a value larger than the normal value. Vibration can also be generated.
Furthermore, by not intentionally adding the compensation value of the temperature compensation control that compensates for temperature dependence, it is possible to generate steering wheel vibrations and warning sounds. For example, in the case of a system that corrects the angle based on the Hall IC + back electromotive voltage, or a system that calculates the angle or angular velocity based on the back electromotive voltage (brush motor system), The resistance model value may be changed intentionally.

Further, a warning sound can be generated by intentionally increasing the dither value for linearizing the nonlinear element to be larger than the normal value.
In the above embodiment, when the electric power steering device is equipped with a control function for preventing the occurrence of vibrations or abnormal noises to improve the steering feeling, By stopping the control function, vibration or abnormal noise as a warning signal can be generated. As a result, the design man-hours for generating the warning signal can be reduced.

  Furthermore, in the said embodiment, although the case where a three-phase brushless motor was applied as an electric motor was demonstrated, a brush motor system can also be applied. In this case, the motor rotation angle and the motor rotation angular velocity may be calculated from the detection value of the steering angle sensor, or the motor rotation angle and the motor rotation angular velocity may be estimated from the back electromotive force of the motor. In the case of a brush motor system, a warning sound can be generated by repeating the driving / stopping of the motor at a very high speed.

1 is a schematic configuration diagram of a vehicle in an embodiment of the present invention. It is a block diagram which shows an example of a steering assistance control apparatus. It is a flowchart which shows the abnormality alerting | reporting process procedure performed with a control arithmetic unit. Equal loudness curve. It is a warning sound frequency calculation map.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering shaft, 3 ... Torque sensor, 10 ... Steering assistance mechanism, 11 ... Reduction gear, 12 ... Three-phase brushless motor, 13 ... Rotor position detection circuit, 20 ... Steering assistance control device, 21 ... Vehicle speed Sensor, 23 ... Control arithmetic unit, 24 ... Motor drive circuit, 25 ... FET gate drive circuit

Claims (9)

An electric motor that applies a steering assist force that reduces the steering burden on the driver to the steering system, and a steering assist command value is calculated based on at least the steering torque, and the electric motor is driven and controlled based on the calculated steering assist command value An electric power steering device comprising control means for
A driving state detecting unit for detecting a driving state of the vehicle, a steering state detecting unit for detecting a steering state by a driver, an abnormality detecting unit for detecting an abnormality of the system, and when the abnormality is detected by the abnormality detecting unit, An informing means for generating a warning signal using at least one of hearing and tactile sensation for the driver according to at least one of the running state detected by the running state detecting means and the steering state detected by the steering state detecting means; An electric power steering apparatus comprising:   The electric power steering apparatus according to claim 1, wherein the notification unit generates the warning signal by each control unit for performing the drive control.   3. The electric power steering apparatus according to claim 1, wherein the traveling state detection unit detects at least one of a vehicle speed, an engine speed, a vehicle acceleration, a yaw rate, and a road surface friction state as the traveling state. .   The steering state detection means detects at least one of a steering torque, a rotation angle of the electric motor, a steering angle, and an energization current amount of the electric motor as the steering state. The electric power steering device according to any one of the above.   The informing means changes at least one of a warning signal type and a warning signal level according to at least one of a running state detected by the running state detecting means and a steering state detected by the steering state detecting means. The electric power steering device according to any one of claims 1 to 4, wherein   The informing means uses the tactile sense when the running condition detected by the running condition detecting means is a running condition in which the vehicle behavior is highly likely to be unstable when a warning signal using the tactile sense is generated. 6. The electric power steering apparatus according to claim 5, wherein generation of a warning signal is limited.   The notification means uses hearing when the driving state detected by the driving state detection unit is a driving state in which the vehicle behavior is likely to be unstable when a warning signal using a tactile sensation is generated. The warning signal using the tactile sensation is generated after the driver determines that the warning signal is unrecognized for a predetermined period after the warning signal is generated. Electric power steering device.   The warning means sets the warning signal level to be larger as the steering state detected by the steering state detection means is a steering state where the steering assist force applied to the steering system is larger. The electric power steering device according to any one of the above.   The notification means detects an abnormality by the abnormality detection means and generates a warning signal, and then, when the driver determines that the warning signal is unrecognized for a predetermined period of time, the warning signal level increases with time. The electric power steering device according to any one of claims 5 to 8, wherein the power is gradually increased.

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