JP4701697B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus capable of automatically controlling a steering angle of a steered wheel without depending on a steering operation.

  In recent years, the steering angle of the steered wheels is automatically controlled, that is, the vehicle is automatically steered regardless of the steering operation, based on the vehicle state quantity detected by various sensors, or the situation signal around the vehicle such as the inter-vehicle distance and the white line detection signal. There has been proposed a vehicle steering apparatus capable of this. For example, the vehicle steering apparatus described in Patent Document 1 includes a brushless motor that is coaxially arranged with the steering shaft. Then, the driving force of the brushless motor is transmitted to the steered wheels via the steering shaft, similarly to the steering force input by the steering operation.

However, when the steering angle (tire angle) of the steering wheel is automatically controlled by the conventional example or the electric power steering device (EPS), the steering system from the steering wheel (steering) to the steering wheel is directly connected. Therefore, the steering is arbitrarily rotated by changing the tire angle by automatic steering. For this reason, the driver is forced to remove his / her hand from the steering wheel, and there is a possibility that the start of the steering operation is delayed when emergency steering is required. Therefore, in order to solve the above problem, in the vehicle steering apparatus described in Patent Document 2, a 1WAY clutch (so-called torque diode) that transmits only the input torque from the steering side is provided on the steering shaft. As a result, the steering can be held unrotatable even during automatic steering, and the steering operation can be quickly performed when emergency steering is required.
JP-A-10-264837 Japanese Patent Application Laid-Open No. 2004-9998

  By the way, when a steering operation occurs during automatic steering, the automatic steering control is generally stopped from the viewpoint of fail-safe. However, in the configuration in which the steering is held unrotatable during automatic steering, the steering angle in the holding state and the original steering angle corresponding to the tire angle are different. For this reason, there is a possibility that the steering torque assumed by the driver and the steering torque actually required may greatly deviate due to the stop of the automatic steering control accompanying the generation of the steering operation. In such a case, the steering feeling becomes steep. May cause significant changes.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle steering apparatus that can suppress a sharp change in steering feeling when automatic steering is stopped. is there.

In order to solve the above-mentioned problem, the invention according to claim 1 is provided in the middle of a steering system between a steering wheel and a steering wheel, and the first rudder of the steering wheel based on the steering angle of the steering wheel. A transmission ratio variable device that varies a transmission ratio between the steering wheel and the steering wheel by adding a second steering angle of the steering wheel based on motor drive to a corner, the transmission ratio variable device, and the steering wheel A reaction force correction device for providing an assist force to the steering system for correcting a reaction force torque acting on the steering wheel, and a control means for controlling the operation of the transmission ratio variable device and the reaction force correction device The control means automatically changes the second rudder angle based on the motor drive to automatically control the rudder angle of the steered wheels regardless of a steering operation. In the automatic steering mode, the vehicle steering device controls the operation of the reaction force correction device to keep the steering wheel unrotatable, and the steering is input to the steering wheel. A steering torque detecting means for detecting torque; and a road surface reaction force detecting means for detecting the road surface reaction force, wherein the control means stops the automatic control when the steering operation occurs, and detects the detected Controlling the operation of the reaction force correcting device to reduce the difference between the anti-road surface reaction force torque required to resist the road surface reaction force obtained on the basis of the steering torque and the detected road surface reaction force. Is the gist.

  According to the above configuration, when automatic steering control is stopped, the reaction force correction device is actuated to provide the steering system with a torque that is insufficient (or excessive) for the anti-road surface reaction force torque as a correction force. Is done. Accordingly, the reaction force torque acting on the steering wheel is substantially equal to that assumed by the driver corresponding to the steering torque input to the steering wheel, thereby suppressing a steep change in steering feeling, The transition from the automatic steering mode to the manual steering by the steering operation, that is, the normal mode can be made smooth.

The gist of the invention described in claim 2 is that the control means gradually reduces the assisting force applied to reduce the difference over time.
According to the said structure, a driver | operator changes the steering torque by the response which changes with the reduction | decrease of the said correction force, ie, the change of reaction force torque. Then, by gradually setting the correction force to substantially zero, the steering torque can be made equal to the required anti-road surface reaction force torque without causing the driver to feel uncomfortable.

  According to a third aspect of the present invention, after the automatic control is stopped, the control means gradually changes the second steering angle based on the motor drive to an angle corresponding to the steering angle in the transmission ratio variable control with time. The gist is to change to

  According to the above configuration, the driver adds a corrected rudder to the steering wheel in accordance with the change in the second rudder angle. As a result, the steering angle in the transmission ratio variable control can be matched with the angle corresponding to the actual steering angle of the steered wheel without causing the driver to feel uncomfortable.

The gist of the invention described in claim 4 is that the control means gradually reduces the second steering angle based on the motor drive with time after the automatic control is stopped.
According to the above configuration, the driver adds a corrected rudder to the steering wheel in accordance with the change in the second rudder angle. As a result, the relationship between the steering angle of the steered wheels and the steering angle can be brought close to a linear one without causing the driver to feel uncomfortable.

The gist of the invention described in claim 5 is that the control means stops the operation of the reaction force correction device when the steering operation is estimated to be sudden steering.
According to the above configuration, it is possible to prevent the operation of the reaction force correction device from interfering with emergency avoidance steering.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus for vehicles which can suppress the rapid change of the steering feeling at the time of an automatic steering stop can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a steering apparatus 1 according to the present embodiment. As shown in the figure, a steering shaft 3 to which a steering wheel (steering) 2 is fixed is connected to a rack 5 via a rack and pinion mechanism 4. It is converted into a reciprocating linear motion of the rack 5 by the and pinion mechanism 4. Then, by changing the rudder angle of the steered wheels 6, that is, the tire angle, by the reciprocating linear motion of the rack 5, the vehicle traveling direction is changed. The steering device 1 of the present embodiment includes a so-called rack assist type EPS actuator 7 that is coaxially arranged with the rack 5. The EPS actuator 7 applies assist force to the steering system by converting assist torque generated by a motor (not shown) as a drive source into reciprocating motion of the rack 5 (power assist). control).

  Further, the steering device 1 of the present embodiment is a transmission ratio variable device that varies the ratio of the steering angle (tire angle) of the steered wheels 6 to the steering angle (steering angle) of the steering wheel 2, that is, the transmission ratio (gear ratio). A variable gear ratio actuator 8 and an ECU 9 as control means for controlling the operation of the variable gear ratio actuator 8 are provided.

  More specifically, the steering shaft 3 includes a first shaft 10 to which the steering 2 is connected and a second shaft 11 to be connected to the rack and pinion mechanism 4. The gear ratio variable actuator 8 includes the first shaft 10 and the first shaft 10. A differential mechanism 12 for connecting the two shafts 11 and a motor 13 for driving the differential mechanism 12 are provided. The gear ratio variable actuator 8 adds the rotation driven by the motor to the rotation of the first shaft 10 accompanying the steering operation and transmits the rotation to the second shaft 11, whereby the steering shaft input to the rack and pinion mechanism 4. The rotation of 3 is increased (or decelerated).

  That is, as shown in FIGS. 2 and 3, the gear ratio variable actuator 8 has the steering angle (ACT angle θta) of the steered wheels based on the motor drive to the steered angle (steer steered angle θts) of the steered wheels 6 based on the steering operation. ) Is added, the gear ratio of the steered wheels 6 with respect to the steering angle θs is varied. In this case, “addition” is defined to include not only addition but also subtraction, and so on. Further, when the “gear ratio of the steered wheels 6 with respect to the steering angle θs” is expressed as an overall gear ratio (steering angle θs / tire angle θt), an overall increase is made by adding the ACT angle θta in the same direction as the steering angle θts. The gear ratio is small (large tire angle θt, see FIG. 2). Then, the overall gear ratio is increased by adding the ACT angle θta in the reverse direction (small tire angle θt, see FIG. 3). The ECU 9 controls the rotation of the motor 13, that is, the ACT angle θta by supplying driving power to the motor 13, thereby controlling the operation of the gear ratio variable actuator 8 (gear ratio variable control).

  Specifically, as shown in FIG. 1, a steering angle sensor 14 and a vehicle speed sensor 15 that detect the steering angle θs of the steering 2 are connected to the ECU 9, and the ECU 9 detects the steering detected by these sensors. Based on the angle θs and the vehicle speed V, an ACT target angle that is a control target amount of the ACT angle θta is calculated. In this embodiment, the ECU 9 has a map (not shown) in which the steering angle θs and the vehicle speed V are associated with the ACT target angle, and the detected steering angle θs and the vehicle speed V are collated with this map. Thus, the ACT target angle is calculated. The ECU 9 is connected to a rotation angle sensor 16 that detects a rotation angle θm of the motor 13. The ECU 9 detects an actual ACT angle θta based on the rotation angle θm. Then, the ECU 9 controls the rotation of the motor 13 so that the ACT angle θta follows the ACT target angle.

  Further, the steering device 1 of the present embodiment is provided between the steering 2 and the gear ratio variable actuator 8, and applies an assisting force (correction torque) for correcting the reaction torque acting on the steering 2 to the steering system. The reaction force correction actuator 20 is provided as a reaction force correction device. The operation of the reaction force correcting actuator 20 is controlled by the ECU 9.

  As shown in FIG. 4, in this embodiment, the gear ratio variable actuator 8 and the reaction force correcting actuator 20 are integrally configured by being housed in a cylindrical housing 21. The housing 21 is fixed to a vehicle body (not shown). Specifically, the housing 21 is composed of an upper housing 22 on the steering 2 side and a lower housing 23 on the rack and pinion mechanism 4 side, and the first shaft 10 constituting the steering shaft 3 has the upper housing 22 in the axial direction. By penetrating, the tip end is extended into the lower housing 23. The gear ratio variable actuator 8 is housed in the lower housing 23, and the reaction force correcting actuator 20 is housed in the upper housing 22.

  More specifically, in the present embodiment, the motor 13 of the gear ratio variable actuator 8 includes a stator 26 fixed to the inner periphery of the lower housing 23 and a hollow cylindrical shape rotatably supported inside the stator 26. The first shaft 10 extending in the lower housing 23 is inserted into the motor shaft 27. A resolver 28 is provided as a rotation angle sensor 16 at one end (steering 2 side) of the motor shaft 27.

  The gear ratio variable actuator 8 has a harmonic drive (wave gear device) 30 as the differential mechanism 12, and the harmonic drive 30 includes a pair of circular splines 31 and 32 that are coaxially arranged, A cylindrical flexible spline 33 arranged coaxially so as to mesh with each spline is provided. Each circular spline 31 and 32 has a different number of teeth, and the flexible spline 33 is placed inside each circular spline 31 and 32 in a state of being bent in an elliptical shape. The teeth are partially meshed with the inner teeth of the circular splines 31 and 32, respectively.

  In this embodiment, the tip of the first shaft 10 inserted into the motor shaft 27 is connected to the first circular spline 31 of the harmonic drive 30 via the connecting member 34, and the second shaft of the harmonic drive 30 is connected. The second shaft 11 is connected to the circular spline 32 via a connecting member 35. And the wave generator 36 which comprises the harmonic drive 30 with each said spline by being arrange | positioned inside the flexible spline 33 at the front-end | tip of the motor shaft 27 is being fixed.

  That is, the rotation of the first shaft 10 due to the steering operation is transmitted from the first circular spline 31 connected to the first shaft 10 to the second circular spline 32 via the flexible spline 33, thereby the second circular spline 32. It is transmitted to the shaft 11. The wave generator 36 is driven by the motor 13 and rotates inside the flexible spline 33 to rotate the elliptical shape of the bent flexible spline 33, that is, the meshing portion with both the circular splines 31 and 32. . Then, the second circular spline 32 rotates in the direction opposite to the rotation direction of the wave generator 36 based on the difference in the number of teeth between the first circular spline 31 and the second circular spline 32, thereby causing the motor 13. Is decelerated and transmitted to the second shaft 11.

  On the other hand, the reaction force correction actuator 20 includes a motor 37 as a drive source and a harmonic drive 38 as a speed reduction mechanism. In the present embodiment, the motor 37 is also a brushless motor. The motor 37 is a stator 41 fixed to the inner periphery of the upper housing 22 and a hollow cylindrical shape that is rotatably supported inside the stator 41. The motor shaft 42 is provided. The first shaft 10 is inserted into the cylinder of the motor shaft 42, thereby penetrating the upper housing 22 in the axial direction, and the tip of the first shaft 10 extends into the lower housing 23.

  The harmonic drive 38 includes a pair of circular splines 43, 44, a flexible spline 45, and a wave generator 46, similar to the above harmonic drive 30, and the first circular spline 43 is connected via a connecting member 47. Connected to the first shaft 10, the second circular spline 44 is fixed to the upper housing 22. The wave generator 46 is connected to one end of the motor shaft 42.

  That is, as in the case of the harmonic drive 30 on the variable gear ratio actuator 8 side, the wave generator 46 is driven by the motor 37 and rotates inside the flexible spline 45, so that the flexible spline 45 and both the circular splines 43 are rotated. , 44 is rotated. As a result, the first circular spline 43 rotates in the direction opposite to the rotation of the wave generator 46, so that the motor torque is transmitted to the first shaft 10 as the correction torque.

  Further, in the reaction force correcting actuator 20 of the present embodiment, a torque sensor 51 as a steering torque detecting means for detecting a steering torque accompanying a steering operation is integrally incorporated. Specifically, the motor shaft 42 of the reaction force correcting actuator 20 is formed with a thin portion 52 whose thickness in the radial direction is thin, and in the vicinity of both end portions 42a and 42b, the thin portion A pair of resolvers 53 and 54 are provided so as to sandwich 52. The thin portion 52 is provided closer to the steering 2 than the rotor portion 55 facing the stator 41. The resolver 53, 54 and the motor shaft 42 constitute a torque sensor 51.

  That is, since the thin portion 52 is formed in the motor shaft 42, the rotation of the first shaft 10 accompanying the steering operation, that is, the steering torque is transmitted through the harmonic drive 38, and the twist is generated. A rotation angle difference is generated between the end portion 42a on the side and the end portion 42b on the rack and pinion mechanism 4 side. The steering torque can be detected by detecting this rotational angle difference by the resolvers 53 and 54 provided in the vicinity of both end portions 42a and 42b.

  As shown in FIG. 1, in this embodiment, the torque sensor 51 (specifically, its resolvers 53 and 54) is connected to the ECU 9, and the ECU 9 detects the steering torque detected by the torque sensor 51. Then, based on the steering torque, a correction torque to be applied to the steering system in order to correct the reaction force torque acting on the steering 2 is determined, and the motor torque generated by the motor 37 through the supply of driving power to the motor 37 is determined. By controlling the above, the operation of the reaction force correction actuator 20, that is, the correction torque applied to the first shaft 10 is controlled.

(Automatic steering control)
Next, an aspect of automatic steering control in the steering device of the present embodiment will be described.
In addition to the normal mode in which the gear ratio variable control is performed in manual steering by a steering operation, the steering device 1 of the present embodiment automatically sets the steering angle (tire angle θt) of the steered wheels 6 regardless of the input of the steering operation. It has an automatic steering mode that automatically changes, that is, executes automatic steering control.

  More specifically, as shown in FIG. 1, the steering device 1 includes various sensors such as a yaw rate sensor 56 in addition to the steering angle sensor 14, the vehicle speed sensor 15, the rotation angle sensor 16, and the torque sensor 51. The ECU 9 is input with a vehicle state quantity such as a yaw rate Ry detected by each of these sensors, or a situation signal around the vehicle such as an inter-vehicle distance and a white line detection signal. Then, the ECU 9 executes the automatic steering control by changing the operation of the variable gear ratio actuator 8, that is, the ACT angle θta, based on these vehicle state quantities and situation signals. Note that a specific aspect of the automatic steering control is a well-known technique, and therefore its description is omitted.

  In the present embodiment, the ECU 9 controls the operation of the reaction force correction actuator 20 so as to hold the steering wheel 2 in a non-rotatable manner during the execution of the automatic steering control (steering holding control). In this embodiment, the ECU 9 performs this holding control by performing position control. As a result, when emergency steering is required, the steering operation can be quickly performed.

[Control mode when automatic steering stops]
The steering device 1 according to the present embodiment also has the above-described automatic steering control from the viewpoint of fail-safe when a steering operation occurs during automatic steering, as in many other vehicle steering devices having an automatic steering mode. To stop. However, in the configuration in which the steering 2 is held non-rotatable in the automatic steering mode in this way, as described above, between the steering torque assumed by the driver and the actual steering torque due to the stop of the automatic steering control. There is a possibility that divergence will occur.

  For example, as shown in FIGS. 5 and 6, when a steering angle (tire angle θt) is generated on the steered wheel 6, the steering system tries to reduce the tire angle θt from the steered wheel 6 side. A force, that is, a road surface reaction force R is applied. Therefore, if the tire angle θt is kept constant, it is necessary to apply a force against the road surface reaction force R from the steering 2 side to the steering system. That is, for example, when a road surface reaction torque Tr that rotates the steering shaft 3 in the direction A (clockwise in the drawing) is applied from the steering wheel 6 side by the road surface reaction force R, the steering shaft is driven from the steering 2 side. It is necessary to apply a torque that rotates 3 in the B direction (counterclockwise in the figure), that is, a road surface reaction torque Tr ′ that resists the road surface reaction torque Tr. As shown in FIG. 5, during automatic steering control, the motor torque Tm corresponding to the resistance road surface reaction torque Tr ′ is applied to the steering shaft 3 (second shaft 11) by the operation of the gear ratio variable actuator 8. The balance is maintained. When the steered wheels 6 are steered in the direction in which the tire angle θt is increased, a motor torque Tm larger than the required anti-road surface reaction torque Tr ′ is applied, and the motor torque Tm is required. When it is smaller than the road surface reaction torque Tr ′, the tire angle θt is small.

  On the other hand, as shown in FIG. 6, when the automatic steering control is stopped by the occurrence of the steering operation, the motor torque Tm basically becomes “0”. When there is a difference between the steering torque Th input from the steering 2 and the required anti-road surface reaction torque Tr ′, the steering feeling changes sharply due to the difference ΔT.

  In consideration of this point, in the steering device 1 of the present embodiment, the ECU 9 controls the operation of the reaction force correction actuator 20 to reduce the difference ΔT. More specifically, the steering apparatus 1 of the present embodiment includes a second torque sensor 57 that detects a road surface reaction force R (road surface reaction force torque Tr) in addition to the torque sensor 51 that detects the steering torque Th. (See FIG. 1). In the present embodiment, the second torque sensor 57 for power assist control provided on the second shaft 11 is used. Based on the steering torque Th detected by the torque sensor 51 and the road surface reaction torque Tr detected by the second torque sensor 57, the ECU 9 calculates the required anti-road surface reaction torque Tr ′ and the steering torque Th. The operation of the reaction force correction actuator 20 is controlled so as to apply a correction torque Tc corresponding to the difference ΔT to the steering shaft 3 (first shaft 10) (reaction force correction control). The anti-road surface reaction torque Tr ′ has a corresponding relationship with the road surface reaction torque Tr, and therefore can be easily obtained simply by changing the way of viewing the torque input direction (how to sign).

  That is, in the steering device 1 of the present embodiment, when the automatic steering control is stopped, the steering torque Th is insufficient (or excessive) with respect to the required anti-road surface reaction torque Tr ′ by the operation of the reaction force correction actuator 20. Minutes) is applied to the steering system (first shaft 10) as the correction torque Tc. Accordingly, the reaction torque acting on the steering wheel 2 is substantially equal to that assumed by the driver corresponding to the steering torque Th input to the steering wheel 2, thereby suppressing a steep change in steering feeling, The transition from the automatic steering mode to the manual steering by the steering operation, that is, the normal mode can be made smooth.

  In the steering device 1 of the present embodiment, the ECU 9 gradually reduces the correction torque Tc to be applied to the steering system in the reaction force correction control with the passage of time. That is, by executing the reaction force correction control, the reaction force torque acting on the steering 2 becomes substantially equal to that assumed by the driver. However, there is still a difference between the required anti-road surface reaction torque Tr ′ and the steering torque Th input to the steering 2, and it is desirable that such deviation be corrected promptly. In this respect, by gradually reducing the correction torque Tc as described above, the driver changes the steering torque Th by the response that changes as the correction torque Tc decreases, that is, by the change in the reaction torque. Then, by gradually setting the correction torque Tc to substantially zero, the steering torque Th can be made equal to the required anti-road surface reaction torque Tr ′ without causing the driver to feel uncomfortable.

  Further, in the steering device 1 of the present embodiment, the ECU 9 stops the automatic steering control, and then sets the ACT angle θta to an angle (see FIGS. 2 and 3) corresponding to the steering angle θs in the normal transmission ratio variable control. Change gradually over time. That is, in the steering device 1 of the present embodiment, during the automatic steering control, the steering 2 is held unrotatable, so the steering angle θs in the held state is different from the original steering angle corresponding to the actual tire angle θt. The difference between the required anti-road surface reaction force torque Tr ′ and the input steering torque Th is also caused by this difference. Therefore, it is desirable that the difference is also corrected promptly. In that respect, as described above, by gradually changing the ACT angle θta, the driver adds a correction rudder to the steering 2 in accordance with the change. As a result, the steering angle θs can be matched with the angle corresponding to the actual tire angle θt without causing the driver to feel uncomfortable.

Next, a processing procedure for automatic steering control in the present embodiment will be described.
As shown in the flowchart of FIG. 7, the ECU 9 first detects various sensor values including the steering torque Th and the road surface reaction force torque Tr (anti-road surface reaction force torque Tr ′) (step 101), and then the steering operation. Whether or not there is is determined (step 102). Note that the steering operation determination in step 102 is, for example, whether or not the absolute value of the steering torque Th continues for a predetermined time or more and whether or not the double differential value of the steering torque Th becomes a predetermined value β1 or more. This is done by determining. And when it determines with there being no steering operation (step 102: NO), the above-mentioned automatic steering control (step 103) and steering holding | maintenance control (step 104) are performed.

  On the other hand, when it is determined in step 102 that there is a steering operation (step 102: YES), the ECU 9 stops the automatic steering control (step 105). Then, the steering holding control is stopped, and the reaction force correction actuator 20 is applied to the first shaft 10 so as to apply the correction torque Tc for reducing the required difference ΔT between the reaction road reaction torque Tr ′ and the steering torque Th. The operation is controlled (reaction force correction control, step 106). In the present embodiment, the correction torque Tc at the start of the reaction force correction control is the amount corresponding to the difference ΔT.

  Next, the ECU 9 determines whether or not there is a steering operation estimated to be sudden steering (step 107). The estimation of the sudden steering in step 107 is performed by, for example, determining whether or not the absolute value of the steering torque Th is equal to or greater than a predetermined value α2 and the twice differential value of the steering torque Th is equal to or greater than a predetermined value β2. Done. If it is determined that there is no sudden steering (step 107: NO), a correction torque gradual change calculation (step 108) for gradually reducing the correction torque Tc to be applied to the first shaft 10 over time, and ACT angle gradual change control (step 109) is executed in which the ACT angle θta is gradually changed over time until an angle corresponding to the steering angle θs in the transmission ratio variable control.

  The correction torque Tc can be calculated, for example, by the following equation, and the function f (t) for decreasing the correction torque Tc with time in the equation is calculated with the passage of time in the correction torque gradual change calculation of step 108. The calculation can be performed by referring to a map having a characteristic that the value of the function f (t) decreases.

Tc = ((Tr′−Th) × A + B) × f (h) (1)
However, “A” is a coefficient depending on the vehicle speed, and “B” is an offset amount.
Next, the ECU 9 determines whether or not the absolute value of the correction torque Tc is “0” and the ACT angle θta is a normal angle by executing the above steps 108 and 109 (step 110). Until the above condition is satisfied, the processes of step 106 to step 110 are repeated. Although not shown for convenience of explanation, it is needless to say that the steering torque Th, the road surface reaction torque Tr, and other various sensor values are successively detected while the processing of Step 106 to Step 110 is repeated. When it is determined that the correction torque Tc is “0” and the ACT angle θta is a normal angle (step 110: YES), the reaction force correction control is ended (step 111).

  In this embodiment, if it is determined in step 107 that there is a steering operation that is estimated to be sudden steering (step 107: YES), the reaction force is immediately corrected so as not to hinder the steering operation. End control.

As described above, according to the present embodiment, the following features can be obtained.
(1) The steering device 1 includes a second torque sensor 57 that detects a road surface reaction force R (road surface reaction force torque Tr) in addition to the torque sensor 51 that detects the steering torque Th. When the automatic steering control is stopped, the ECU 9 determines the required anti-road surface reaction torque Tr based on the steering torque Th detected by the torque sensor 51 and the road surface reaction torque Tr detected by the second torque sensor 57. The operation of the reaction force correction actuator 20 is controlled so as to apply a correction torque Tc for reducing the difference ΔT between the angle 'and the steering torque Th to the steering shaft 3.

  With such a configuration, when the automatic steering control is stopped, the operation of the reaction force correction actuator 20 causes the steering torque Th to be insufficient (or excessive) with respect to the required anti-road surface reaction torque Tr ′. Torque is applied to the steering system (first shaft 10) as the correction torque Tc. Accordingly, the reaction torque acting on the steering wheel 2 is substantially equal to that assumed by the driver corresponding to the steering torque Th input to the steering wheel 2, thereby suppressing a steep change in steering feeling, The transition from the automatic steering mode to the manual steering by the steering operation, that is, the normal mode can be made smooth.

  (2) The ECU 9 gradually reduces the correction torque Tc applied to the steering system in the reaction force correction control with time. With this configuration, the driver changes the steering torque Th by the response that changes as the correction torque Tc decreases, that is, the change in the reaction torque. Then, by gradually setting the correction torque Tc to substantially zero, the steering torque Th can be made equal to the required anti-road surface reaction torque Tr ′ without causing the driver to feel uncomfortable.

  (3) After the automatic steering control is stopped, the ECU 9 gradually changes the ACT angle θta over time to an angle corresponding to the steering angle θs in the normal transmission ratio variable control (see FIGS. 2 and 3). With such a configuration, the driver adds a correction rudder to the steering 2 in accordance with the change in the ACT angle θta. As a result, the steering angle θs can be matched with the angle corresponding to the actual tire angle θt without causing the driver to feel uncomfortable.

  (4) If the ECU 9 determines that there is a steering operation that is estimated to be sudden steering, the reaction force correction control ends. Thereby, it is possible to prevent the operation of the reaction force correcting actuator 20 from interfering with the emergency avoidance steering.

In addition, you may change each said embodiment as follows.
In the present embodiment, the present invention is embodied in the steering device 1 including the EPS actuator 7 and is used for power assist control provided on the second shaft 11 as road surface reaction force detection means for detecting the road surface reaction force R. The second torque sensor 57 was used. However, the present invention is not limited to this, and a hydraulic power steering device or a steering device that does not perform power assist may be embodied as long as it has a road surface reaction force detection means instead of the second torque sensor 57. That is, the road surface reaction force detecting means is not limited to the torque sensor that can directly detect the road surface reaction force torque Tr, but indirectly detects the road surface reaction force R (road surface reaction force torque Tr) by estimation based on the vehicle state quantity. You may do. For the estimation, for example, the relationship between the steering angle θs, the vehicle speed, etc., and the road surface reaction force R is obtained in advance by experiments, simulations, etc., and the relationship is made a map. And it can carry out easily by referring this map.

  In the present embodiment, the variable gear ratio actuator 8 and the reaction force correction actuator 20 are integrally configured by being housed in the housing 21. However, the reaction force correction actuator 20 is connected to the steering 2 and the gear. As long as it is provided between the variable ratio actuator 8, it may be provided separately. The gear ratio variable actuator 8 may be integrated with the EPS actuator 7, and the housing thereof may not be fixed to the vehicle body (not shown).

  In the present embodiment, the torque sensor 51 for detecting the steering torque accompanying the steering operation is integrated with the reaction force correction actuator 20, but is provided separately from the reaction force correction actuator 20. There may be.

  In the present embodiment, after the automatic steering control is stopped, the ACT angle θta is gradually changed over time to an angle corresponding to the steering angle θs in the normal transmission ratio variable control. However, the present invention is not limited to this, and the ACT angle θta may be gradually reduced with time. With such a configuration, the relationship between the tire angle θt and the steering angle θs can be approximated to a linear one without giving the driver a sense of incongruity.

The schematic block diagram of the steering device of this embodiment. Action | operation explanatory drawing of transmission ratio variable control. Action | operation explanatory drawing of transmission ratio variable control. Sectional drawing of a gear ratio variable actuator and a reaction force correction actuator. Explanatory drawing which shows the balance of the force which acts on the steering system at the time of automatic steering control. Explanatory drawing which shows the balance of the force which acts on the steering system at the time of automatic steering control stop. Explanatory drawing which shows the process sequence of automatic steering control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering wheel (steering), 3 ... Steering shaft, 5 ... Rack, 6 ... Steering wheel, 8 ... Gear ratio variable actuator, 9 ... ECU, 10 ... 1st shaft, 11 ... 2nd shaft, DESCRIPTION OF SYMBOLS 13 ... Motor, 20 ... Reaction force correction actuator, 37 ... Motor, 51 ... Torque sensor, 57 ... Second torque sensor, θs ... Steering angle, θt ... Tire angle, θts ... Steer turning angle, θta ... ACT angle, Th: Steering torque, R: Road surface reaction force, Tr: Road surface reaction torque, Tr ': Anti-road surface reaction torque, Tc: Correction torque, ΔT: Difference.

Claims (5)

A second rudder angle of the steered wheel based on motor drive is added to a first rudder angle of the steered wheel that is provided in the middle of the steering system between the steering wheel and the steered wheel and is based on the steering angle of the steering wheel. A transmission ratio variable device that varies the transmission ratio between the steering wheel and the steering wheel, and a reaction force torque that is provided between the transmission ratio variable device and the steering wheel and that acts on the steering wheel. And a control means for controlling the operation of the transmission ratio variable device and the reaction force correction device, wherein the control means is the second motor based on the motor drive. An automatic steering mode for automatically controlling the steering angle of the steered wheels without changing the steering operation by changing the steering angle. , Said a vehicle steering apparatus which controls the operation of the reaction force correction unit so as to rotatably hold the steering wheel,
Steering torque detection means for detecting steering torque input to the steering wheel;
Road surface reaction force detecting means for detecting the road surface reaction force,
The control means is required to stop the automatic control when the steering operation occurs and to resist the road surface reaction force obtained based on the detected steering torque and the detected road surface reaction force. Controlling the operation of the reaction force correction device to reduce the difference with the reaction surface reaction torque.
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 1,
The vehicle steering apparatus according to claim 1, wherein the control means gradually reduces the auxiliary force applied to reduce the difference with time. In the vehicle steering device according to claim 1 or 2,
The control means is characterized in that after the automatic control is stopped, the second steering angle based on the motor drive is gradually changed over time to an angle corresponding to the steering angle in the transmission ratio variable control. Vehicle steering system. In the vehicle steering device according to claim 1 or 2,
The vehicle steering apparatus, wherein the control means gradually reduces the second rudder angle based on the motor drive with time after the automatic control is stopped. In the vehicle steering device according to any one of claims 1 to 4,
The control means stops the operation of the reaction force correction device when the steering operation is estimated to be rapid steering.

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