JP2007203801A - Steering device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device which moderates turning behavior of a steering wheel and stabilizes behavior of a vehicle when an abnormality occurs in a steering system. <P>SOLUTION: When a VGRS_ECU 46 determines that abnormality occurs in an EPS motor 33, it determines a traveling state of a vehicle based on a vehicle speed V and a steering angle θ. If the vehicle speed V is not larger than a predetermined vehicle speed V<SB>0</SB>and the steering angle θ is not less than a predetermined steering angle θ<SB>0</SB>, it controls a gradual operation of a VGRS motor 21 so that the steering wheel 11 gradually turns to the neutral position direction. On the other hand, if the vehicle speed V is larger than the vehicle speed V<SB>0</SB>and the steering angle θ is smaller than the steering angle θ<SB>0</SB>, it controls the follow-up operation of the motor 21 so that left and right front wheels FW1, FW2 follow up the curved radius R. The turning behavior of the steering wheel 11 can be moderated and the behavior of the vehicle can be stabilized by switching the operation state of the motor according to the traveling state of the vehicle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering input shaft that rotates integrally with a turning operation of a steering wheel, a steering output shaft that is connected to a steering mechanism that steers steered wheels, and a rotation angle of the steering input shaft. A transmission ratio variable actuator that rotates the steering output shaft by changing a transmission ratio of a rotation angle of the steering output shaft, and an operation force reduction that generates torque for reducing an operation force of the steering handle by the driver The present invention relates to a vehicle steering apparatus including an actuator and an actuator control device that controls the operation of the transmission ratio variable actuator and the operation force reducing actuator.

  Conventionally, for example, a vehicle steering control device as shown in Patent Document 1 below is known. This conventional vehicle steering control device includes a transmission ratio variable mechanism, detects the curvature radius of a curve existing in front of the travel path using the position information and road map information obtained from the navigation system, and detects the vehicle speed. Based on the curve and the curve, the transmission ratio of the transmission ratio variable mechanism is set. As a result, the handle operability during curve driving is improved.

Conventionally, for example, a vehicle having a variable steering angle ratio steering device and an electric power steering device as shown in Patent Document 2 below is also known. In this vehicle, when the voltage supplied to the electric motor constituting the electric power steering device decreases, in other words, when the auxiliary steering torque for assisting the manual steering torque decreases, the variable steering angle ratio steering device is put into a slow state. It is supposed to move to. As a result, even when the electric power steering apparatus is not operated, the variable steering angle ratio steering apparatus is set in the slow state, so that the driver can easily perform the steering operation.
JP 11-310146 A Japanese Patent No. 3517833

  However, the conventional apparatus and the conventional vehicle do not sufficiently consider the influence of the abnormality occurring in the steering system on the behavior stability of the vehicle, and the positive response to the disturbance of the behavior of the vehicle is disclosed. It has not been. That is, in a vehicle in a turning state, for example, when the assist force for the steering operation by the driver is no longer applied, the reaction force input to the steering handle increases, and the steering handle easily turns sharply in the neutral position direction. Become. At this time, there is a possibility that the steered state of the steered wheels will change as the steering wheel turns sharply, and the behavior of the vehicle may change as the steered state changes. Further, when the behavior of the vehicle changes, it is necessary for the driver to turn the steering handle with a large steering torque to stabilize the behavior of the vehicle, which imposes a physical burden. Therefore, it is desired to prevent the behavior change from occurring on the vehicle side.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle that makes the turning behavior of the steering wheel moderate and stabilizes the behavior of the vehicle when an abnormality occurs in the steering system. It is in providing a steering device.

  In order to achieve the above object, the present invention is characterized by a steering input shaft that rotates integrally with a turning operation of a steering handle, and a steering output shaft that is connected to a steering mechanism that steers steered wheels. A variable transmission ratio actuator for rotating the steering output shaft by changing a transmission ratio of rotation from the steering input shaft to the steering output shaft, and for reducing the operating force of the steering handle by the driver In a vehicle steering apparatus comprising an operation force reducing actuator that generates torque and an actuator control device that controls the operation of the transmission ratio variable actuator and the operation force reduction actuator, the actuator control device may be the transmission ratio variable actuator or An abnormality occurrence determination means for determining whether or not an abnormality has occurred in the operating state of the operating force reduction actuator, and a running condition related to turning of the vehicle It is determined that an abnormality has occurred in the operation of the variable transmission ratio actuator or the operating force reduction actuator by the traveling state determining means for determining the curve state, the curve state detecting means for detecting the curve state of the traveling road, and the abnormality occurrence determining means. Then, in accordance with the traveling state determined by the traveling state determining means, the operating state of the transmission ratio variable actuator or the operating force reducing actuator that is operating normally is gently rotated in the neutral position direction. It is composed of a slow operating state or an actuator operating state switching means for switching to a following operating state in which the steered wheels are steered by following the curve state detected by the curve state detecting means.

  In this case, the actuator control device further includes a vehicle speed detection unit that detects a vehicle speed of the vehicle, and an operation amount detection unit that detects a rotation operation amount of the steering handle, and the travel state determination unit includes: Based on the vehicle speed detected by the vehicle speed detection means and the amount of turning operation of the steering handle detected by the operation amount detection means or the curve state detected by the curve state detection means, the travel related to the turning of the vehicle It is good to determine the state.

  The actuator operating state switching means, when it is determined by the traveling state determining means that the vehicle is in a traveling state where the vehicle turns with a large turning amount, the transmission ratio variable actuator or operating force reduction actuator that is operating normally. When the travel state determination means determines that the vehicle is in a travel state in which the vehicle turns with a small amount of turn, the normally operating transmission ratio variable actuator or operation force reduction The operating state of the actuator may be switched to the following operating state.

  According to these, when the actuator control device determines that an abnormality has occurred in the operating state of the variable transmission ratio actuator or the operating force reduction actuator by the abnormality occurrence determination unit, the traveling state relating to the turning of the vehicle is determined by the traveling state determination unit. Can be determined. Then, the actuator control device can switch the transmission ratio variable actuator or the operating force reduction actuator that is normally operated by the actuator operation state switching means to the slow operation state or the follow operation state based on the determined traveling state. .

  That is, the traveling state determination means is a traveling state in which the vehicle turns with a large turning amount or a turning state with a small turning amount based on the vehicle speed and the turning operation amount or curve state of the steering handle. Can be determined. Then, when it is determined that the vehicle is in a traveling state in which the vehicle turns with a large turning amount, the actuator operation state switching means can switch the normally operating transmission ratio variable actuator or operating force reduction actuator to the slow operation state. it can. In addition, when it is determined that the vehicle is in a traveling state where the vehicle turns with a small turning amount, the actuator operation state switching means can switch the normally operating transmission ratio variable actuator or operating force reduction actuator to the follow operation state. it can.

  As a result, an abnormality has occurred in the variable transmission ratio actuator or operating force reduction actuator, and when the vehicle is in a traveling state where the vehicle turns with a large turning amount, the reaction force input to the steering handle increases, but it operates normally. By switching the variable transmission ratio actuator or the operating force reduction actuator to the slow operating state, the turning behavior in the neutral direction of the steering wheel can be made gentle. Therefore, it is not necessary for the driver to input a large steering torque to rotate the steering handle, and the physical burden can be reduced. Further, by gently turning the steering wheel, the change in the behavior of the vehicle can be moderated, and the driver can easily stabilize the behavior of the vehicle.

  Also, when the transmission ratio variable actuator or operating force reduction actuator is abnormal and the vehicle is in a traveling state where the vehicle turns with a small turning amount, the variable transmission ratio actuator or operating force reduction actuator that is operating normally follows. By switching to the operating state, the turning of the steered wheels can be made to follow in accordance with the curve state of the traveling road. As a result, even when the vehicle turns with a relatively large vehicle speed and a small turning amount, the turning of the steered wheels can be adjusted to the curve state, so that the change in the behavior of the vehicle due to the abnormality occurring in the steering system is effective. Therefore, the behavior of the vehicle can be stabilized very easily.

  According to another feature of the present invention, the actuator control device further matches the operation reference position of the transmission ratio variable actuator whose operation state is switched by the actuator operation state switching means with a neutral position of the steering handle. There is also a correction means for correcting. In this case, the correction means may correct the operation reference position of the variable transmission ratio actuator when the vehicle is traveling straight ahead.

  According to these, the correction means can match the neutral position of the steering wheel that is directly operated by the driver with the operation reference position of the variable transmission ratio actuator that directly steers the steered wheels. Further, by correcting the operation reference position of the variable transmission ratio actuator when the vehicle is traveling straight ahead, the neutral position of the steering wheel can be more accurately matched. Therefore, for example, even when the vehicle continuously travels after the transmission ratio variable actuator is switched to the slow operation state or the follow operation state, the driver can turn the steering wheel without feeling uncomfortable.

  Hereinafter, a vehicle steering apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a vehicle steering apparatus according to an embodiment of the present invention.

  The vehicle steering apparatus includes a steering handle 11 that is turned by a driver to steer left and right front wheels FW1 and FW2 as steered wheels. The steering handle 11 is fixed to the upper end of the steering input shaft 12, and the lower end of the steering input shaft 12 is connected to a variable gear ratio actuator 20 as a transmission ratio variable actuator. The variable gear ratio actuator 20 includes an electric motor 21 (hereinafter, this electric motor is referred to as a VGRS motor 21) and a speed reducer 22, and the speed reducer 22 with respect to the rotation amount (or rotation angle) of the steering input shaft 12. The rotation amount (or rotation angle) of the steering output shaft 13 connected to is appropriately changed.

  The motor housing of the VGRS motor 21 is integrally connected to the steering input shaft 12, and rotates integrally according to the turning operation of the steering handle 11 by the driver. The drive shaft 21a of the VGRS motor 21 is connected to the speed reducer 22, and the rotational force of the VGRS motor 21 is transmitted to the speed reducer 22 via the drive shaft 21a. The reduction gear 22 is configured by a predetermined gear mechanism (for example, a planetary gear mechanism or the like), and the turning output shaft 13 is connected to the gear mechanism. Thereby, when the rotational force of the VGRS motor 21 is transmitted through the drive shaft 21a, the speed reducer 22 appropriately decelerates the rotation of the drive shaft 21a by a predetermined gear mechanism and transmits the rotation to the steering output shaft 13. can do. Therefore, the variable gear ratio actuator 20 connects the steering input shaft 12 and the steering output shaft 13 so as to be relatively rotatable via the drive shaft 21 a of the VGRS motor 21. The ratio of the rotation amount of the steering output shaft 13 to the rotation amount, that is, the transmission ratio (gear ratio) of rotation from the steering input shaft 12 to the steering output shaft 13 can be changed as appropriate.

  Further, the steering device includes a turning gear unit 30 as a turning mechanism connected to the lower end of the turning output shaft 13. The steered gear unit 30 is, for example, a gear unit adopting a rack and pinion type, and the rotation of the pinion gear 31 integrally assembled to the lower end of the steered output shaft 13 is transmitted to the rack bar 32. It has become. The steered gear unit 30 includes an electric motor 33 (hereinafter referred to as a steering force reduction actuator) for reducing a steering force (more specifically, a steering torque) input to the steering handle 11 by the driver. This electric motor is provided with an EPS motor 33), and torque (so-called assist force) generated by the EPS motor 33 is transmitted to the rack bar 32. With this configuration, the rotational force of the steering output shaft 13 is transmitted to the rack bar 32 via the pinion gear 31, and the assist force of the EPS motor 33 is transmitted to the rack bar 32. As a result, the rack bar 32 is displaced in the axial direction by the rotational force from the pinion gear 31 and the assist force of the EPS motor 33. Therefore, the left and right front wheels FW1, FW2 connected to both ends of the rack bar 32 are steered left and right.

  Next, the electric control device 40 as an actuator control device that controls the operation of the above-described variable gear ratio actuator 20 (specifically, the VGRS motor 21) and the steered gear unit 30 (specifically, the EPS motor 33) will be described. . The electric control device 40 includes a vehicle speed sensor 41, a steering angle sensor 42, a rotation angle sensor 43, and a steering torque sensor 44. The vehicle speed sensor 41 detects and outputs the vehicle speed V of the vehicle. The steering angle sensor 42 detects the amount of rotation of the steering handle 11, that is, the amount of rotation of the steering input shaft 12, and outputs it as the steering angle θ. The rotation angle sensor 43 detects the rotation amount of the drive shaft 21a of the VGRS motor 21 and outputs it as a rotation angle Θ. Note that the steering angle sensor 42 and the rotation angle sensor 43 output the rotation angle “0” when the vehicle maintains the straight traveling state. The rotation position of the steering handle 11 and the drive shaft 21a when the rotation angle of “0” is output from the steering angle sensor 42 and the rotation angle sensor 43 is referred to as a neutral position.

  The steering torque sensor 44 detects torque input to the steering output shaft 13 when the driver rotates the steering handle 11, and outputs the detected torque as steering torque Td. That is, the steering torque Td is obtained from the EPS motor based on the force input to the left and right front wheels FW1 and FW2 from the road surface, such as, for example, torque caused by friction between the left and right front wheels FW1 and FW2 and the road surface This is the torque input by the driver against the reaction force (torque) obtained by reducing the assist force by 33.

  The electric control device 40 also operates an electronic control unit 46 (hereinafter referred to as VGRS_ECU 46) for controlling the operation of the VGRS motor 21 of the variable gear ratio actuator 20 and an operation of the EPS motor 33 of the steered gear unit 30. And an electronic control unit 47 (hereinafter, this electronic control unit is referred to as EPS_ECU 47). These VGRS_ECU 46 and EPS_ECU 47 are mainly composed of a microcomputer composed of a CPU, a ROM, a RAM and the like. Here, the VGRS_ECU 46 and the EPS_ECU 47 can communicate with each other via, for example, a communication line A constructed in the vehicle.

  A vehicle speed sensor 41, a steering angle sensor 42, and a rotation angle sensor 43 are connected to the input side of the VGRS_ECU 46, and a steering angle sensor 42 and a steering torque sensor 44 are connected to the input side of the EPS_ECU 47. The VGRS_ECU 46 and the EPS_ECU 47 execute various programs using the detection values detected by the sensors 41 to 44 to control the operations of the VGRS motor 21 and the EPS motor 33. For this reason, drive circuits 48 and 49 for driving the VGRS motor 21 and the EPS motor 33 are connected to the output sides of the VGRS_ECU 46 and the EPS_ECU 47, respectively. Further, in the drive circuits 48 and 49, current detectors 48a and 49a for detecting the drive current values flowing in the VGRS motor 21 and the EPS motor 33 are provided.

  The VGRS_ECU 46 and the EPS_ECU 47 are connected via a communication line A to a navigation device 50 that detects the current position of the host vehicle and provides various information to the driver.

  As shown in FIG. 2, the navigation device 50 includes a navigation electronic control unit 51 (hereinafter, this electronic control unit is referred to as a navigation ECU 51). The navigation ECU 51 also has a microcomputer composed of a CPU, ROM, RAM, and the like as main components, and controls the operation of the navigation device 50 in an integrated manner. The navigation ECU 51 is connected with a GPS (Global Posioning System) receiver 52, a gyroscope 53, a storage device 54, and a vehicle speed sensor 41.

  The GPS receiver 52 receives a radio wave for detecting the current position of the host vehicle from the satellite and outputs the detected current position of the host vehicle as, for example, coordinate data. The gyroscope 53 detects and outputs the turning speed of the vehicle for detecting the traveling direction of the host vehicle. The navigation ECU 51 acquires the vehicle speed V output from the vehicle speed sensor 41 in addition to acquiring the detection values output from the GPS receiver 52 and the gyroscope 53, and detects the current position of the host vehicle. To do.

  The storage device 54 includes storage media such as a hard disk, a CD-ROM, and a DVD-ROM, and a drive device for these recording media. The storage device 54 stores various data including various programs executed by the navigation ECU 51 and road data. Here, road data refers to road types such as road type data representing road types (highways, national roads, prefectural roads, etc.), road shape data representing road shapes (coordinates representing curve start and end points, curve radius R, etc.), and the like. It is configured to include various data.

  Next, the operation of the steering device configured as described above will be described first from the state in which the steering device is operating normally (hereinafter referred to as normal operation). When an ignition switch (not shown) is turned on, the VGRS_ECU 46 and the EPS_ECU 47 start controlling the variable gear ratio actuator 20 and the steered gear unit 30, respectively. The VGRS_ECU 46 inputs the current vehicle speed V from the vehicle speed sensor 41, and determines a transmission ratio G corresponding to the detected vehicle speed V with reference to a map as shown in FIG. Note that the transmission ratio G during normal operation has a characteristic that it uniformly decreases as the vehicle speed V increases and increases uniformly as the vehicle speed V decreases.

  In this state, when the turning operation of the steering handle 11 is started by the driver, the steering input shaft 12, the variable gear ratio actuator 20, and the steered output shaft 13 also start to rotate. In accordance with the driver's turning operation, the VGRS_ECU 46 inputs the steering angle θ detected by the steering angle sensor 42 and multiplies the input steering angle θ by the determined transmission ratio G, whereby the steering input shaft The rotation angle δ of the steering output shaft 13 with respect to the steering angle θ of 12 is calculated.

  Next, the VGRS_ECU 46 calculates the operation amount of the VGRS motor 21 necessary for realizing the calculated rotation angle δ of the steered output shaft 13, that is, the target rotation angle Θh of the drive shaft 21a. More specifically, the motor housing of the VGRS motor 21 connected integrally with the steering input shaft 12 rotates in accordance with the turning operation of the steering handle 11 by the driver. At this time, the VGRS_ECU 46 controls the drive circuit 48 to drive the VGRS motor 21 in order to rotate the steered output shaft 13 in accordance with the rotation of the motor housing. Next, the VGRS_ECU 46 calculates the target rotation angle Θh so that the turning output shaft 13 has the rotation angle δ with reference to the steering angle θ of the steering input shaft 12.

  As described above, since the drive shaft 21a of the VGRS motor 21 and the steered output shaft 13 are coupled by the predetermined gear mechanism of the variable gear ratio actuator 20, the rotation angle δ of the steered output shaft 13 sets α to a predetermined value. If the gear ratio is δ, the relationship of δ = α × Θh is established. Therefore, the VGRS_ECU 46 calculates the target rotation angle Θh of the drive shaft 21a as Θh = δ / α.

  Then, when the VGRS_ECU 46 calculates the target rotation angle Θh, it is driven without overshooting using the current detection value by the current detector 48a until the rotation angle Θ detected by the rotation angle sensor 43 reaches the target rotation angle Θh. The circuit 48 is controlled to rotate the drive shaft 21a of the VGRS motor 21. As a result, the turning output shaft 13 is rotated to a rotation angle δ that is a transmission ratio G with respect to the steering angle θ of the steering input shaft 12. Therefore, since the pinion gear 31 meshing with the rack bar 32 rotates at a rotation angle Δ represented by the sum of the steering angle θ and the rotation angle δ by the rotation operation of the steering handle 11 by the driver, the left and right front wheels FW1, FW2 are The vehicle is steered at a turning angle Δ equal to the rotation angle Δ.

  Thus, the driver can obtain a good steering feeling according to the vehicle speed V by turning the left and right front wheels FW1, FW2 at the turning angle Δ. That is, when the detected vehicle speed V increases, the transmission ratio G is determined to be small, so that the steered output shaft 13 is rotated in the opposite direction relative to the rotational direction of the steering input shaft 12. In this case, since the turning angle Δ of the left and right front wheels FW1 and FW2 is represented by the difference between the steering angle θ and the rotation angle δ, the left and right front wheels FW1 and FW2 are in response to the turning operation of the steering handle 11 by the driver. It will be steered gently. As a result, the driver can easily operate the steering handle 11 and can stabilize the behavior of the vehicle during high-speed traveling.

  Further, since the transmission ratio G is determined to be large when the detected vehicle speed V decreases, the steered output shaft 13 is rotated relatively more in the rotational direction of the steering input shaft 12. In this case, since the turning angle Δ of the left and right front wheels FW1 and FW2 is represented by the sum of the steering angle θ and the rotation angle δ, the left and right front wheels FW1 and FW2 with respect to the turning operation of the steering handle 11 by the driver. Is quickly steered. Thereby, for example, in garage entry, the amount of rotation operation of the steering handle 11 by the driver can be reduced, and the operation burden on the driver can be reduced.

  On the other hand, the EPS_ECU 47 assists the rack bar 32 by driving the EPS motor 33 that reduces the input steering torque Td in accordance with the magnitude of the steering torque Td input by the driver via the steering handle 11. Transmit power. That is, the EPS_ECU 47 inputs the steering torque Td from the steering torque sensor 44 and sets a control amount for driving the EPS motor 33 according to the magnitude of the steering torque Td. Then, the EPS_ECU 47 controls the drive circuit 49 to drive the EPS motor 33 without overshooting using the current detection value by the current detector 49a based on the set control amount. Thereby, the steering torque Td related to the turning operation of the steering handle 11 by the driver is reduced, and the physical burden on the driver is reduced.

  Thus, during normal operation, the VGRS_ECU 46 and the EPS_ECU 47 cooperate with each other to control the operation of the VGRS motor 21 and the EPS motor 33, so that the driver can turn the vehicle very easily. By the way, when the power supply to the EPS motor 33 is interrupted or an abnormal drive current flows while the vehicle is turning, an abnormality occurs in the operation of the EPS motor 33 and an appropriate assist force is applied. In some cases, the signal cannot be transmitted to the rack bar 32.

  Thus, in the state where the right and left front wheels FW1 and FW2 are being steered when an appropriate assist force is not applied by the EPS motor 33, for example, the self-alignment torque is increased and the reaction force input to the steering handle 11 is increased. Becomes larger. When a large reaction force is input, the driver inputs to maintain the current steering angle Δ of the left and right front wheels FW1, FW2, in other words, to maintain the current steering angle θ of the steering wheel 11. The steering torque Td increases. As described above, in a situation where the steering torque Td input to the steering handle 11 becomes large, the steering state of the left and right front wheels FW1, FW2 may change and the behavior of the vehicle may change.

  That is, when the reaction force input to the steering handle 11 is increased, the steering handle 11 is easily rotated in the neutral position direction. At this time, as the turning angle Δ of the left and right front wheels FW1 and FW2 is larger, the steering handle 11 is steeperly rotated in the neutral position direction. In this case, if the driver does not input a sufficiently large steering torque Td, the behavior of the vehicle may be disturbed. In a situation where the vehicle passes a curve, for example, the driver inputs a large steering torque Td, and a steering angle corresponding to the shape of the curve (more specifically, the size of the curve radius R). It is necessary to maintain θ, that is, the turning angle Δ of the left and right front wheels FW1, FW2. For this reason, a large burden is imposed on the driver.

  Therefore, the VGRS_ECU 46 executes the VGRS motor operation control program shown in FIG. 4 at a predetermined short time interval when the ignition switch is turned on. The VGRS_ECU 46 prevents the steering handle 11 from turning sharply toward the neutral position even when an abnormality occurs in the operation of the EPS motor 33 (hereinafter referred to as an abnormal operation), and the vehicle The operation state of the VGRS motor 21 is switched and controlled so that the curve can be easily passed. Hereinafter, the VGRS motor operation control program for controlling the operation state of the VGRS motor 21 will be described in detail.

  In step S10, the VGRS_ECU 46 starts executing the VGRS motor operation control program. In step S11, the VGRS_ECU 46 determines whether an abnormality has occurred in the operation of the EPS motor 33 based on the abnormality occurrence information supplied from the EPS_ECU 47. Hereinafter, the abnormality occurrence determination process will be specifically described.

  As described above, the EPS_ECU 47 inputs the drive current value detected by the current detector 49a of the drive circuit 49. The drive current value becomes an abnormal value when, for example, a mechanical failure that hinders the operation of the EPS motor 33 occurs. For this reason, when an abnormal drive current value is detected by the current detector 49a, the EPS_ECU 47 sends abnormality occurrence information indicating that an abnormality has occurred in the operation of the EPS motor 33 to the VGRS_ECU 46 via the communication line A. Supply. Further, the EPS_ECU 47 supplies abnormality occurrence information to the VGRS_ECU 46 even when electric power supplied from a battery (not shown) is interrupted due to an electrical failure, for example.

  The EPS_ECU 47 can also supply the abnormality occurrence information to other systems mounted on the vehicle. Thus, for example, by turning on a warning light provided in the meter cluster or outputting a sound, it is possible to notify the driver that an abnormality has occurred in the EPS motor 33.

  As described above, when the abnormality occurrence information is acquired from the EPS_ECU 47, the VGRS_ECU 46 determines “Yes” in Step S11 and proceeds to Step S12. On the other hand, if the abnormality occurrence information is not acquired from the EPS_ECU 47, since the EPS motor 33 is operating normally, the VGRS_ECU 46 determines “No” and proceeds to step S21 to temporarily end the execution of the VGRS motor operation control program. To do. Then, after a predetermined short time has elapsed, the execution of the VGRS motor operation control program is started again in step S10.

  In step S12, the VGRS_ECU 46 determines whether or not the vehicle speed V detected by the vehicle speed sensor 41 is equal to or lower than a predetermined vehicle speed Vo set in advance. That is, if the detected vehicle speed V is equal to or lower than the predetermined vehicle speed Vo, the VGRS_ECU 46 determines “Yes” and proceeds to step S13. The predetermined vehicle speed Vo is a vehicle speed at which it can be determined that the vehicle is traveling at a low speed, such as when the vehicle is parked or when turning left or right at an intersection.

  In step S13, the VGRS_ECU 46 determines whether or not the steering angle θ detected by the steering angle sensor 42 is equal to or larger than a predetermined steering angle θo set in advance. That is, if the detected steering angle θ is equal to or greater than the predetermined steering angle θo, the VGRS_ECU 46 determines “Yes” and proceeds to step S14. Note that the predetermined steering angle θo is a steering angle at which it can be determined that the steering handle 11 is largely rotated, for example, when the vehicle is parked or when turning right or left at an intersection. Then, Step S12, Step S13 and Step S16 described later in the VGRS motor operation control program constitute the traveling state determination means in the present invention.

  Here, considering the situation where the determination processing in both step S12 and step S13 is established as “Yes”, the vehicle is traveling at a low speed and the steering angle θ of the steering wheel 11 is large, that is, the left and right front wheels FW1. , The turning angle Δ of FW2 is large. In this situation, since the left and right front wheels FW1, FW2 are steered greatly and the vehicle turns with a large turning amount, the self-alignment torque increases as the vehicle runs as described above. Therefore, the reaction force input to the steering handle 11 is increased, and the steering handle 11 is easily rotated in the neutral position direction. Therefore, the VGRS_ECU 46 controls the VGRS motor 21 so that the steering handle 11 is gently rotated to the neutral position in subsequent steps S14 and S15.

  More specifically, in a situation where the left and right front wheels FW1 and FW2 are returned to the neutral position by the self-alignment torque, the drive shaft 21a is connected via the rack bar 32, the pinion gear 31, the steered output shaft 13, and the speed reducer 22. Rotate. Therefore, the VGRS_ECU 46 applies a drive current to the VGRS motor 21 so as to generate a torque that suppresses the rotation of the drive shaft 21a so that the change in the rotation angle Θ of the drive shaft 21a becomes gentle. Supply. The VGRS_ECU 46 continues to supply drive current to the VGRS motor 21 until the detected steering angle θ becomes “0” representing the neutral position of the steering handle 11 in step S14.

  Thus, when the drive current is supplied to the VGRS motor 21, the rotation of the drive shaft 21a is suppressed, and the steering input shaft 12 and the steering handle 11 that are integrally coupled to the electromagnetically connected motor housing. Is also suppressed. As a result, the reaction force input to the steering handle 11 can be reduced by operating the VGRS motor 21 as compared to the case where the reaction force is input to the steering handle 11 without operating the VGRS motor 21. . As a result, the driver can maintain the current steering angle θ by inputting a relatively small steering torque Td, and can prevent the steering handle 11 that is not intended by the driver from turning sharply. . Therefore, the steering handle 11 can be gently rotated to the neutral position to the extent that the driver can operate, and the vehicle behavior can be effectively prevented from being disturbed. If the steering angle θ is substantially “0” in step S15, “Yes” is determined and the process proceeds to step S19. Steps S14 and S15 in the VGRS motor operation control program constitute the actuator operation switching means in the present invention.

  If the detected steering angle θ is smaller than the predetermined steering angle θo in step S13, the VGRS_ECU 46 determines “No”, and the execution of the VGRS motor operation control program is temporarily ended in step S21. This is because the vehicle travels at a low speed and the steering handle 11 is not largely turned. In other words, the left and right front wheels FW1, FW2 are not steered greatly, and therefore the reaction force input to the steering handle 11 is small. This is because even if the steering handle 11 is sharply turned in the neutral position direction, the effect of the turning of the steering handle 11 on the behavior change of the vehicle is small. Therefore, the VGRS_ECU 46 temporarily ends the execution of the VGRS motor operation control program without controlling the operation of the VGRS motor 21.

  On the other hand, if the vehicle speed V is greater than the predetermined vehicle speed Vo in step S12, the VGRS_ECU 46 determines “No” and proceeds to step S16. In step S16, the VGRS_ECU 46 determines whether or not the detected steering angle θ is smaller than a predetermined steering angle θo. That is, if the detected steering angle θ is smaller than the predetermined steering angle θo, the VGRS_ECU 46 determines “Yes” and proceeds to step S17.

  Here, considering the situation where the determination process of the step S12 is established as “No” and the determination process of the step S16 is “Yes”, the vehicle is traveling at a medium to high speed, and the steering handle 11 In which the steering angle θ of the left and right front wheels FW1, FW2 is small. In this situation, since the left and right front wheels FW1, FW2 are steered small, as described above, the self-alignment torque generated as the vehicle travels is relatively small. On the other hand, since the detected vehicle speed V is relatively large, returning the steering handle 11 (the left and right front wheels FW1, FW2) to the neutral position direction makes it easier for the vehicle behavior to change. For this reason, in step S17 and step S18, the VGRS_ECU 46, more specifically, the left and right front wheels FW1 so that the vehicle turns following the road shape based on the road shape data acquired from the navigation ECU 51 of the navigation device 50. The operation of the VGRS motor 21 is controlled so that the turning angle Δ of FW2 matches the road shape.

  More specifically, the VGRS_ECU 46 acquires road shape data representing the road shape through which the vehicle is currently passing, that is, the curve radius R, from the navigation device 50. That is, the navigation ECU 51 of the navigation device 50 detects the current position of the host vehicle based on the detection values output from the GPS receiver 52, the gyroscope 53, and the vehicle speed sensor 41. Then, the navigation ECU 51 extracts the road shape data at the current position of the host vehicle from the road shape data stored in the storage device 54 based on the detected current position. As described above, when the road shape data is extracted, the navigation ECU 51 supplies the data to the VGRS_ECU 46 via the communication line A.

  In the VGRS_ECU 46, road shape data representing the curve radius R supplied from the navigation ECU 51 is acquired. Then, the VGRS_ECU 46 refers to a map as shown in FIG. 5 set experimentally in advance based on the curve radius R represented by the acquired road shape data and the detected vehicle speed V from the vehicle speed sensor 41. Then, the turning angle Δ that can pass following the road (curve) that is currently traveling is determined. Next, the VGRS_ECU 46 determines the target rotation angle Θh of the drive shaft 21a of the VGRS motor 21 in order to realize the determined turning angle Δ.

  That is, as described above, the target rotation angle Θh of the drive shaft 21a can be calculated as Θh = δ / α using the rotation angle δ of the steered output shaft 13 and the predetermined gear ratio α. The steered angle Δ can be calculated by adding the steering angle θ and the rotation angle δ. Therefore, based on these, the target rotation angle Θh of the drive shaft 21a can be calculated as Θh = (Δ−θ) / α. After calculating the target rotation angle Θh, the VGRS_ECU 46 controls the drive circuit 48 without overshooting until the rotation angle Θ detected by the rotation angle sensor 43 reaches the target rotation angle Θh, thereby driving the VGRS motor 21. The shaft 21a is rotated.

  Thereby, when the vehicle passes the curve, the left and right front wheels FW1 and FW2 are appropriately secured in the turning angle Δ, and the vehicle can turn following the curve of the curve radius R. Then, in step S18, the VGRS_ECU 46 continues the operation control of the VGRS motor 21 in step S15 by determining “No” until acquisition of the passage information indicating that the vehicle has passed the end point of the curve from the navigation ECU 51. To do. And if passage information is acquired from navigation ECU51, it will judge with "Yes" and will progress to Step S19. In this case, it goes without saying that after passing the curve, the driver returns the steering handle 11 to the neutral position in the same manner as during normal driving.

  Here, the passage information supplied from the navigation ECU 51 will be briefly described. The navigation ECU 51 searches the road shape data based on the current position of the host vehicle detected as described above, and extracts end point coordinates representing the end point of the currently traveling curve. Then, the navigation ECU 51 repeatedly determines whether or not the current position and the end point coordinates of the host vehicle match, and if the current position and the end point coordinates match, the navigation ECU 51 sends passage information to the VGRS_ECU 46 via the communication line A. Supply. Steps S17 and S18 in the VGRS motor operation control program constitute the actuator operation switching means in the present invention.

  If the detected steering angle θ is greater than or equal to the predetermined steering angle θo in step S16, the VGRS_ECU 46 determines “No” and executes the processes of steps S14 and S15 described above. This takes into consideration the situation in which the vehicle is traveling at a medium to high speed and the steering handle 11 is greatly rotated, for example, the situation in which the vehicle passes the hairpin curve. In this case, since the left and right front wheels FW1 and FW2 are steered greatly, the reaction force input to the steering handle 11 is large, and the steering handle 11 rotates sharply in the neutral position direction to change the behavior of the vehicle. There is a possibility to give. Therefore, the VGRS_ECU 46 controls the VGRS motor 21 so that the steering handle 11 gently rotates in the neutral position direction. In this case, since the reaction force input to the steering wheel 11 is reduced, the driver can easily maintain the steering angle θ of the steering wheel 11. Therefore, until passing the hairpin curve, the appropriate steering angle θ, in other words, the steering angle Δ of the left and right front wheels FW1, FW2 can be maintained, and after passing the hairpin curve, the steering handle 11 is gently moved toward the neutral position. It can be rotated.

  Further, in this case, as necessary, until the vehicle passes the hairpin curve, the steering angle Δ of the left and right front wheels FW1, FW2 is made to follow the curve radius R by the processing of step S17 and step S18. It is also possible to perform the slow motion control of the VGRS motor 21 by controlling the VGRS motor 21 and performing the processes of Step S14 and Step S15 after passing the hairpin curve. As a result, it is possible to prevent a sudden change in the behavior of the vehicle while passing the curve, and to moderate the turning behavior of the steering handle 11 after passing the curve.

  After the process of step S15 or step S18, the VGRS_ECU 46 determines whether or not the vehicle is currently traveling in step S19. That is, based on the detected vehicle speed V from the vehicle speed sensor 41, the VGRS_ECU 46 determines “Yes” if the vehicle speed V is not substantially “0”, and proceeds to step S20.

  In step S20, the VGRS_ECU 46 corrects the rotation position of the drive shaft 21a rotated based on the above-described operation control of the VGRS motor 21 so as to coincide with the neutral position in the straight traveling state, that is, the reference operation position. More specifically, the VGRS_ECU 46 inputs the detected steering angle θ from the steering angle sensor 42 when the vehicle is traveling. If the steering angle θ is input as “0”, the VGRS_ECU 46 sets the rotation position of the drive shaft 21a to the neutral position, in other words, sets the rotation angle Θ to “0”. The motor 21 is driven.

  More specifically, the VGRS_ECU 46 inputs straight-ahead information from the navigation ECU 51 of the navigation device 50. Here, the straight traveling information from the navigation ECU 51 will be described. When the vehicle is in a straight traveling state, the turning speed output from the gyroscope 53 is “0”. For this reason, when the navigation ECU 51 acquires the turning speed of “0”, the navigation ECU 51 outputs straight-ahead information to the VGRS_ECU 46.

  The VGRS_ECU 46 rotates the drive shaft 21a of the VGRS motor 21 so that the rotation angle Θ input from the rotation angle sensor 43 becomes “0” in a state where the straight traveling information is input. Thereby, the rotation position of the steering handle 11 and the rotation position of the drive shaft 21a in the straight traveling state can be matched with the neutral position, that is, the operation reference position, respectively. Therefore, the neutral position of the steering wheel 11 and the traveling state (straight traveling state) of the vehicle can be matched, and the driver does not feel uncomfortable. Then, the VGRS_ECU 46 proceeds to step S21 and temporarily ends the execution of the VGRS motor operation control program.

  On the other hand, if the detected vehicle speed V is “0” in step S19, the vehicle is in a stopped state, so the VGRS_ECU 46 determines “No” and executes the VGRS motor operation control program in step S21. Exit once. In this case, as described above, it is necessary that the vehicle is traveling with respect to the neutral position correction of the drive shaft 21a. Therefore, if the vehicle is in the stopped state in step S19, the same processing as in step S20 is executed again to correct the rotational position of the drive shaft 21a when the vehicle is in the running state. Note that step S19 and step S20 in the VGRS motor operation control program constitute correction means in the present invention.

  As can be understood from the above description, according to the present embodiment, when the EPS motor 33 is abnormal and the vehicle is in a traveling state where the vehicle turns with a large turning amount, the input to the steering wheel 11 is reversed. Although the force increases, the VGRS motor 21 that is operating normally can be switched to a slow operation, so that the turning behavior of the steering handle 11 in the neutral direction can be moderated. Therefore, it is not necessary for the driver to input a large steering torque Td to rotate the steering handle 11, and the physical burden can be reduced. Further, by gently turning the steering handle 11, the change in the behavior of the vehicle can be moderated, and the driver can easily stabilize the behavior of the vehicle.

  Further, when the EPS motor 33 is abnormal and the vehicle is in a traveling state in which the vehicle turns with a small turning amount, the currently operating road is switched by switching the normally operating VGRS motor 21 to the following operation. The turning angle Δ of the left and right front wheels FW1, FW2 can be made to follow in accordance with the curve radius R. As a result, even when the vehicle turns with a small turning amount at a relatively high vehicle speed V, it is possible to effectively suppress changes in the behavior of the vehicle due to an abnormality occurring in the steering system, and it is extremely easy to Can be stabilized.

  Further, by correcting the neutral position of the VGRS motor 21, that is, the operation reference position when the vehicle is traveling straight ahead, the neutral position of the steering wheel 11 can be more accurately matched. Therefore, after the VGRS motor 21 is switched to the slow operation or the follow operation, for example, even when the vehicle is continuously driven, the driver can turn the steering handle 11 without feeling uncomfortable.

  In carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, the detected steering angle θ is compared with the predetermined steering angle θo in the determination process in step S13 or step S16 in the VGRS motor operation control program. However, instead of this, it is also possible to determine the magnitude of the curve radius R through which the vehicle is currently passing.

  That is, the VGRS_ECU 46 acquires the road shape data (specifically, the curve radius R) of the currently passing curve from the navigation ECU 51 of the navigation device 50 in step S13 or step S16 of the VGRS motor operation control program. And it compares with the predetermined curve radius Ro set beforehand. Specifically, in step S13, the VGRS_ECU 46 compares the acquired curve radius R with a predetermined curve radius Ro, and determines whether the curve radius R is equal to or less than the predetermined curve radius Ro.

  According to this determination, in order to pass through the small curve radius R, the steering handle 11 needs to be largely rotated, in other words, the left and right front wheels FW1, FW2 need to be largely steered. The same determination can be made. In step S16, it is determined whether or not the curve radius R is greater than or equal to a predetermined curve radius Ro. According to this determination, in order to pass through the large curve radius R, the steering handle 11 is rotated by a small amount, so that the same determination as in step S16 of the above embodiment can be performed. Therefore, even in this case, the same effect as the above embodiment can be expected.

  Further, in the above embodiment, when an abnormal operation occurs in the EPS motor 33, the VGRS_ECU 46 controls the operation of the VGRS motor 21 and controls the turning behavior of the steering handle 11 according to the turning state of the vehicle. The steering angle Δ of the left and right front wheels FW1 and FW2 was made to follow the road shape. However, if an operation abnormality occurs in the VGRS motor 21 based on the current detection of the current detector 48a of the drive circuit 48, the EPS_ECU 47 controls the EPS motor 33 slowly or follows the same as in the above embodiment. It is also possible to carry out operation control. Even in this case, the same effect as in the above embodiment can be expected.

  Further, in the above embodiment, the EPS gear 33 is provided in the steered gear unit 30 so that the assist force is transmitted to the rack bar 32. However, regarding the arrangement of the EPS motor 33, for example, if the assist force can be transmitted to the turning operation of the steering handle 11 by the driver, the EPS motor 33 is disposed so as to transmit the assist force to the steering output shaft 13, for example. Any arrangement may be used. Moreover, in the said embodiment, although the rack and pinion type was employ | adopted and implemented for the steered gear unit 30, it can also implement by employ | adopting a ball screw mechanism, for example. In addition, the variable gear ratio actuator 20 is configured by the VGRS motor 21 and the speed reducer 22. However, for example, a step motor may be adopted for the VGRS motor 21 and the speed reducer 22 may be omitted.

1 is a schematic view of a vehicle steering apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram schematically showing a configuration of the navigation device of FIG. 1. It is a graph which shows the relationship between a vehicle speed and a transmission ratio. It is a flowchart which shows the VGRS motor operation control program performed by VGRSECU of FIG. It is a graph which shows the relationship between the curve radius and steering angle which change according to a detection vehicle speed.

Explanation of symbols

FW1, FW2 ... front wheel, 11 ... steering handle, 12 ... steering input shaft, 13 ... steering output shaft, 20 ... variable gear ratio actuator, 21 ... VGRS motor, 21a ... drive shaft, 22 ... reduction gear, 30 ... steering Gear unit, 31 ... pinion gear, 32 ... rack bar, 33 ... EPS motor, 40 ... electric control device, 41 ... vehicle speed sensor, 42 ... steering angle sensor, 43 ... rotation angle sensor, 44 ... steering torque sensor, 46 ... VGRS_ECU 47, EPS_ECU, 48, 49, drive circuit, 50, navigation device

Claims (5)

A steering input shaft that rotates integrally with the turning operation of the steering handle, a steering output shaft that is connected to a steering mechanism that steers the steered wheels, and from the steering input shaft to the steering output shaft A transmission ratio variable actuator that changes the transmission ratio of rotation to rotate the steering output shaft, an operation force reduction actuator that generates torque for reducing the operation force of the steering wheel by the driver, and the transmission ratio variable In a vehicle steering apparatus including an actuator and an actuator control device that controls an operation of an operation force reducing actuator,
The actuator control device;
An abnormality occurrence determining means for determining whether an abnormality has occurred in an operating state of the transmission ratio variable actuator or the operating force reduction actuator;
Traveling state determining means for determining a traveling state relating to turning of the vehicle;
A curve state detection means for detecting a curve state of the road,
When it is determined by the abnormality occurrence determination means that an abnormality has occurred in the operation of the transmission ratio variable actuator or the operating force reduction actuator, it is operating normally according to the traveling state determined by the traveling state determination means. The operating state of the transmission ratio variable actuator or the operation force reducing actuator is made to follow the slowly operating state in which the steering handle is gently rotated in the neutral position direction or the curve state detected by the curve state detecting means of the steered wheel. A vehicle steering apparatus comprising: an actuator operation state switching means for switching to a follow-up operation state for turning. In the vehicle steering apparatus according to claim 1,
The actuator controller is
Furthermore, vehicle speed detection means for detecting the vehicle speed of the vehicle,
An operation amount detecting means for detecting a rotation operation amount of the steering handle;
The traveling state determination means includes
Based on the vehicle speed detected by the vehicle speed detection means and the amount of turning operation of the steering handle detected by the operation amount detection means or the curve state detected by the curve state detection means, the travel related to the turning of the vehicle A vehicle steering apparatus characterized by determining a state. In the vehicle steering apparatus according to claim 1,
The actuator operating state switching means is
When the traveling state determining means determines that the vehicle is in a traveling state where the vehicle turns with a large turning amount, the operating state of the normally operating transmission ratio variable actuator or operating force reducing actuator is switched to the slow operating state. When the traveling state determining means determines that the vehicle is in a traveling state where the vehicle turns with a small turning amount, the operating state of the normally operating transmission ratio variable actuator or operating force reducing actuator is changed to the following operating state. A vehicle steering apparatus characterized by switching. In the vehicle steering apparatus according to claim 1,
The actuator control device further includes:
A vehicle steering apparatus comprising correction means for correcting an operation reference position of the transmission ratio variable actuator whose operation state is switched by the actuator operation state switching means so as to coincide with a neutral position of the steering handle. In the vehicle steering apparatus according to claim 4,
The correction means includes
A vehicle steering apparatus that corrects an operation reference position of the variable transmission ratio actuator when the vehicle is traveling straight ahead.

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