JP2009078694A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of preventing or suppressing a detection error of a steered angle of tire wheels even when a vehicle travels on a road, a surface of which affects to the traveling direction of the vehicle. <P>SOLUTION: The steering device includes a steering gear ratio variable mechanism 30 for varying a steering gear ratio α/γ between a steering angle α of a steering wheel 11 and the steered angle γ of the tire wheels 13a and 13b. The device includes a road surface condition determining means 61 for determining whether the road surface condition affects to the traveling direction of the vehicle, and a steering gear ratio controlling means 62 for controlling the steering gear ratio α/γ when it is determined by the road surface condition determining means 61 that the road surface condition affects to the traveling direction of the vehicle, so that a rotation of the steering wheel 11 to move the tire wheels 13a and 13b at a maximum steered angle on one side to an opposite maximum steered angle on the other side becomes one revolution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steering apparatus including a steering gear ratio variable mechanism that changes a steering gear ratio between a steering angle of a steering wheel and a turning angle of a wheel.

  Conventionally, in a steering device having a steering gear ratio variable mechanism that changes the steering gear ratio between the steering angle of the steering wheel and the steering angle of the wheel, when steering is started from a steered state, it is caused by backlash. There is known a steering device that can suppress a change in steering torque and reduce a sense of discomfort in steering (see, for example, Patent Document 1).

In this steering device, the input shaft connected to the steering handle and the output shaft connected to the steering gear box are connected via a steering gear ratio variable mechanism (transmission ratio variable mechanism), and the rotation of the input shaft Is transmitted to the output shaft through the steering gear ratio variable mechanism. As shown in FIG. 5, a backlash B exists between the drive gear 101 and the passive gear 102 constituting the steering gear ratio variable mechanism. Immediately after steering from the hold state, the steering gear ratio variable mechanism is driven by the electric motor so as to sufficiently reduce the backlash B by the control device, and the backlash B is substantially eliminated. Thus, the drive control of the steering gear ratio variable mechanism is continued. Thus, by driving the steering gear ratio variable mechanism so as to sufficiently eliminate the backlash, a change in the steering torque due to the backlash is sufficiently suppressed.
JP 2000-159134 A

  In the steering device having the above-described conventional configuration, the traveling direction of the vehicle is basically determined by the turning angle of the wheel according to the steering angle of the steering wheel. However, the traveling direction of the vehicle may be determined not only by the turning angle of the wheel but also by the road surface shape. For example, on a road surface on which a kite is formed, the kite functions as a guide groove for guiding wheels, so that the vehicle tries to travel along the direction in which the kite extends. In the case of such a road surface shape that affects the traveling direction of the vehicle, since the traveling direction of the vehicle is not determined only by the turning angle of the wheel, the driver may misidentify the turning angle of the wheel arranged at the blind spot. is there.

  The present invention has been made in view of the above, and provides a steering device that can prevent or suppress misidentification of the turning angle of a wheel even in the case of a road surface shape that affects the traveling direction of the vehicle. With the goal.

In order to achieve the above object, a first invention provides a steering apparatus including a steering gear ratio variable mechanism that changes a steering gear ratio between a steering angle of a steering wheel and a steering angle of a wheel.
Road surface shape determining means for determining whether or not the road surface shape affects the traveling direction of the vehicle;
If it is determined by the road surface shape determining means that the road surface shape affects the traveling direction of the vehicle, it is necessary to change the wheel from one maximum turning angle state to the other maximum turning angle state. Steering gear ratio control means for controlling the steering gear ratio so that the number of rotations of the steering handle is approximately one rotation;
Is provided.

  Further, the second invention is the steering device according to the first invention, wherein the steering gear ratio control means is determined by the road surface shape determining means to have a road surface shape that affects the traveling direction of the vehicle. And controlling the steering gear ratio so that the number of rotations of the steering wheel required to change the wheel from one maximum turning angle state to the other maximum turning angle state is approximately one rotation, In the vicinity of the neutral position of the steering wheel, the steering gear ratio is controlled to be larger than in the vicinity of the vicinity of the neutral position.

A third invention is a steering device according to the first or second invention, wherein an assist mechanism for assisting steering of the steering wheel in a steering direction;
When it is determined by the road surface shape determining means that the road surface shape affects the traveling direction of the vehicle, compared to the case where the road surface shape determining means determines that the traveling direction of the vehicle is not affected by the road surface shape, Assist force control means for controlling the assist force of the assist mechanism in the vicinity of a neutral position of the steering handle;
Is further provided.

  According to the first aspect of the present invention, when the road surface shape affects the traveling direction of the vehicle, the number of rotations of the steering wheel (locking) that changes the wheel from the state of one maximum turning angle to the state of the other maximum turning angle.・ By making the two-lock rotation number) approximately 1 rotation, the visual effect of the steering wheel trajectory as a pie chart, based on the steering angle of the steering wheel arranged in the field of view, of the wheel arranged in the blind spot The steered angle can be easily grasped, and misidentification of the steered angle of the wheel can be prevented or suppressed.

  According to the second aspect of the invention, the change in the steering angle with respect to the amount of change in the steering angle during straight traveling is controlled by largely controlling the steering gear ratio in the vicinity of the neutral position of the steering wheel as compared with the vicinity of the vicinity of the neutral position. The amount can be reduced, and even when the lock-to-lock rotation speed is approximately one rotation, the stability during straight traveling can be increased.

  According to the third aspect of the invention, by controlling the assist force of the assist mechanism near the neutral position of the steering wheel to be small, the steering wheel can be made heavy when traveling straight, and the lock-to-lock rotation speed is approximately 1. Even in the case of rotation, the stability during straight traveling can be increased.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of the configuration of the steering device of the present invention. As shown in FIG. 1, the steering device supports a steering handle 11, an input shaft 12 that rotates together with the steering handle 11, a pair of left and right front wheels 13a and 13b, and front wheels 13a and 13b so as to be rotatable with respect to the vehicle body. A pair of left and right steering knuckles 14a, 14b, a pair of left and right tie rods 15a, 15b connected to the steering knuckles 14a, 14b, a rack bar 16 having a pair of left and right tie rods 15a, 15b at both ends, a rack & Steering gear ratio for connecting the pinion shaft 18 connected to the rack bar 16 via the pinion mechanism 17, the output shaft 20 connected to the pinion shaft 18 via the gear box 19, and the input shaft 12 and the output shaft 20. And a variable mechanism 30. Further, as shown in FIG. 1, the steering device includes an assist mechanism 40 that assists the steering of the steering handle 11 in the steering direction.

  When the input shaft 12 rotates around its own axis according to the steering of the steering handle 11, the output shaft 20 rotates around its own axis via the steering gear ratio variable mechanism 30. The rotation of the output shaft 20 is decelerated (increased torque) by the gear box 19 and transmitted to the pinion shaft 18. The rotational force transmitted to the pinion shaft 18 is converted into a linear force by a rack and pinion mechanism 17 comprising a pinion 17a formed at the tip of the pinion shaft 18 and a rack 17b formed at the center of the rack bar 16. The rack bar 16 is driven in the vehicle width direction. By the operation of the rack bar 16, the pair of left and right front wheels 13a and 13b supported by the steering knuckles 14a and 14b are steered via the pair of left and right tie rods 15a and 15b. In this manner, the left and right front wheels 17a and 17b are steered according to the steering of the steering handle 11, and the traveling direction of the vehicle is determined.

  As shown in FIG. 1, the assist mechanism 40 includes an electric motor 41 that rotates forward and backward, a torque sensor 42 that detects a steering torque T applied to the input shaft 12 by steering the steering handle 11, and an ECU that controls the electric motor 41. (Electronic Control Unit) 43, and a steering angle sensor 51 (see FIG. 2) that detects the steering angle α of the steering handle 11 is connected to the assist mechanism 40.

  The ECU 43 is constituted by a microcomputer, and includes, for example, a CPU, a ROM for storing control programs, a readable / writable RAM for storing calculation results, a timer for measuring time, and a counter for measuring the number of times of calculation and the like. , An input interface, and an output interface.

  The ECU 43 sets a target value Ap of the assist force A that assists the rotational movement of the input shaft 12 based on the steering angle α and the steering torque T, and controls the electric motor 41 so that the assist force A becomes the target value Ap. . The output of the electric motor 41 is transmitted to the input shaft 12 via a worm gear (not shown) on the electric motor 41 side and a worm wheel (not shown) on the input shaft 12 side, and steering of the steering handle 11 is steered in the steering direction. To assist. For setting the target value Ap of the assist force A, electronic data defining the relationship among the steering angle α, the steering torque T, and the target value Ap stored in the ROM at the time of manufacture of the vehicle is used.

  FIG. 2 is a functional block diagram showing an example of the configuration of the steering gear ratio variable mechanism 30 and the connecting parts. As shown in FIG. 2, the steering gear ratio variable mechanism 30 includes an electric motor 31 that rotates forward and backward, a lock device 32, and an ECU 33 that controls the electric motor 31 and the lock device 32.

  The lock device 32 is electrically switched between a lock-on state and a lock-off state, and in the lock-on state, transmission of the rotational force of the electric motor 31 is prevented and relative rotation between the input shaft 12 and the output shaft 20 is prevented. In the lock-off state, transmission of the rotational force of the electric motor 31 is allowed, and relative rotation between the input shaft 12 and the output shaft 20 is allowed.

  Like the ECU 43, the ECU 33 is configured by a microcomputer. The ECU 33 outputs an electric signal corresponding to the vehicle speed V and a steering angle sensor 51 that outputs an electric signal corresponding to the steering angle α of the steering handle 11. A vehicle speed sensor 52 is connected.

  The ECU 33 sets the target value βp of the relative rotation angle β between the input shaft 12 and the output shaft 20 based on the steering angle α and the vehicle speed V, and the relative rotation angle β between the input shaft 12 and the output shaft 20 is the target value βp. The electric motor 31 is controlled so that the steering gear ratio is changed. Here, the steering gear ratio is defined as α / γ using the steering angle α of the steering wheel 11 and the turning angle γ of the front wheels 13a and 13b. The target value βp of the relative rotation angle β is calculated using electronic data that defines the relationship among the steering angle α, the vehicle speed V, and the target value βp, which is stored in the ROM when the vehicle is manufactured.

  Thus, the steering gear ratio variable mechanism 30 sets the lock device 32 in the lock-off state, allows relative rotation between the input shaft 12 and the output shaft 20, and controls the electric motor 31 based on the steering angle α and the vehicle speed V. Thus, the steering gear ratio α / γ is changed. Further, the steering gear ratio variable mechanism 30 can also prevent the relative rotation between the input shaft 12 and the output shaft 20 by changing the lock device 32 to the lock-on state and not changing the steering gear ratio α / γ.

  Further, as shown in FIG. 2, the ECU 33 includes road surface shape determination means 61, steering gear ratio control means 62, and assist force control means 63 as a characteristic configuration. Further, the ECU 33 includes a control mode switch 53 operated according to the user's will, a navigation device 54, an off-road guidance system 55 that assists a user who is unfamiliar with off-road driving, a throttle position sensor 56 for an accelerator pedal, a wheel speed. Various sensors such as the sensor 57 are connected.

  The road surface shape determining means 61 determines whether or not the road surface shape affects the traveling direction of the vehicle.

  For example, data on the ON / OFF state of the control mode switch 53 is used as a determination element of the road surface shape determination unit 61. In this case, the ECU 33 obtains an electrical signal indicating the on / off state from the control mode switch 53, determines that the road surface shape affects the traveling direction of the vehicle in the on state, and in the off state, It is determined that the road surface shape does not affect the traveling direction.

  The control mode switch 53 is disposed at a position where the user can easily operate, preferably at a position where the user can operate without greatly changing the visual field during driving. For example, you may arrange | position in the center part of the instrument panel front in a vehicle interior, and may be arrange | positioned in a meter. The control mode switch 53 may be a pressure-sensitive switch displayed on a display such as a liquid crystal display or a push button switch. The indicator that displays the pressure sensitive switch may also serve as the indicator of the navigation device 54. In this case, a composite image obtained by combining the current position data of the vehicle with the map data is supplied and displayed on the display.

  Further, the current position data of the vehicle provided by the navigation device 54 can be used as the determination element of the road surface shape determination means 61. The ROM of the ECU 33 stores map data indicating a place that affects the traveling direction of the vehicle when the vehicle is manufactured. When the ECU 33 acquires the current position data of the vehicle from the navigation device 54, the ROM 33 stores the map data. The map data is read out to determine whether or not the road surface shape affects the traveling direction of the vehicle. When the current position of the vehicle matches the location registered in the map data, the ECU 33 determines that the road surface shape affects the traveling direction of the vehicle, and the current location of the vehicle matches the location registered in the map data. When not, it is determined that the road surface shape does not affect the traveling direction of the vehicle. For example, a place other than a paved road is set as a place that affects the traveling direction of the vehicle.

  The on / off state of the off-road guidance system 55 can be used as a determination element of the road surface shape determination unit 61. In this case, the ECU 33 is supplied with an electric signal indicating an on / off state from the off-road guidance system 55. When the off-road guidance system 55 is operated to be in the on state, the vehicle is traveling on an uneven road that is rich in ups and downs, so the traveling direction of the vehicle is easily affected by the road surface shape. Therefore, when the ECU 33 acquires an electrical signal indicating the on state from the off-road guidance system 55, the ECU 33 determines that the road surface shape affects the traveling direction of the vehicle. It is determined that the road surface shape does not affect the direction.

  Further, as the determination element of the road surface shape determination means 61, travel resistance data calculated based on information from various sensors such as the accelerator pedal slot position sensor 56 and the wheel speed sensor 57 can be used. Even if the amount of operation of the accelerator pedal increases, when the rotation of the wheels 13a and 13b is not accelerated and the running resistance from the road surface is large, the traveling direction of the vehicle is easily affected by the running resistance from the road surface. Therefore, the ECU 33 calculates the running resistance based on the operation amount of the accelerator pedal and the rotational acceleration of the wheel. When the running resistance is equal to or greater than the threshold, the ECU 33 determines that the road surface shape affects the traveling direction of the vehicle, and the running resistance. Is less than the threshold value, it is determined that the road surface shape does not affect the traveling direction of the vehicle.

  Further, in the case of a four-wheel drive vehicle including the transfer 58 that distributes the output of the transmission to the front wheel output and the rear wheel output, the determination element of the road surface shape determination means 61 includes the shift range of the sub-transmission of the transfer 58. The data shown can be used. When the shift range of the sub-transmission of the transfer 58 is operated at a low speed and the output torque of the transfer 58 is amplified, the vehicle is traveling on the road surface because the vehicle is traveling at a low speed on a bad road that requires a high driving force. Easy to be affected by shape. Therefore, the ECU 33 determines that the road surface shape affects the traveling direction of the vehicle when the shift range is operated at a low speed, and the road surface affects the traveling direction of the vehicle when the shift range is operated at a high speed. It is determined that it is not a shape. The electrical signal indicating the shift range of the sub-transmission of the transfer 58 is provided to the ECU 33 from a switch circuit that is turned on / off in accordance with the operation of the shift lever of the sub-transmission, for example.

  The road surface shape determination means 61 may use one or more of these determination elements. For example, when the control mode switch 53 and the navigation device 54 are used in combination, the vehicle position data when the control mode switch 53 is on is acquired from the navigation device 54, and the location of the road surface shape that affects the traveling direction of the vehicle is obtained. The map data shown may be newly created and recorded in the RAM of the ECU 33 to supplement the same kind of map data recorded in the ROM of the ECU 33 at the time of vehicle manufacture.

  When it is determined by the road surface shape determining means 61 that the steering gear ratio control means 62 has a road surface shape that affects the traveling direction of the vehicle, the steering gear ratio control means 62 changes the wheel from one maximum turning angle state to the other maximum turning angle state. The steering gear ratio α / γ is controlled so that the number of rotations of the steering wheel 11 necessary for setting the state (hereinafter referred to as “lock-to-lock rotation number”) is approximately one rotation.

  First, a case where the road surface shape determining unit 61 determines that the road surface shape does not affect the traveling direction of the vehicle will be described. In this case, the steering gear ratio α / γ is set so that the lock-to-lock rotation speed is approximately 3 rotations, for example, as in a general steering device. By setting the lock-to-lock rotation speed to about 3 times, the wheels 13a and 13b can be gently steered with respect to the steering handle 11, and the vehicle can be operated stably even at high speeds. be able to.

  Next, a case where the road surface shape determination unit 61 determines that the road surface shape affects the traveling direction of the vehicle will be described. In this case, as described above, the steering gear ratio α / γ is controlled so that the lock-to-lock rotation speed is approximately one rotation. If the lock-to-lock rotation speed is changed from approximately 3 rotations to approximately 1 rotation, it becomes difficult to operate the vehicle stably at high speed, but the road surface shape determining means 61 affects the traveling direction of the vehicle. When it is determined that the shape is a shape, the vehicle often travels on a rough road at a low speed, and the stability at the time of high speed travel is not important.

  The control of the lock-to-lock rotation speed is realized by controlling the electric motor 31 of the steering gear ratio variable mechanism 30. Specifically, for example, the electric motor so that the target value βp of the relative rotation angle β between the input shaft 12 and the output shaft 20 is approximately twice the rotation angle α of the input shaft 12 (the steering angle α of the steering handle 11). 31 is controlled. As a result, the rotation angle of the output shaft 20 with respect to the rotation angle of the input shaft 12 can be approximately tripled, and the lock-to-lock rotation speed can be changed from approximately 3 rotations to approximately 1 rotation.

  When the lock-to-lock rotation speed is set to approximately one rotation, when the wheels 13a and 13b are changed from the state of one maximum turning angle to the state of the other maximum turning angle, the locus of the steering handle 11 is substantially circular. Draw. Therefore, based on the visual effect of the pie chart drawn by the locus of the steering handle 11, the turning angle γ of the wheels 13a and 13b arranged in the blind spot can be easily grasped based on the steering angle α of the steering handle 11 arranged in the field of view. can do. Thereby, even if it is the case of the road surface shape which affects the advancing direction of a vehicle, the misidentification of the steering angle (gamma) of wheel 13a, 13b can be prevented or suppressed.

  The steering gear ratio control means 62 controls the steering gear ratio α / γ so that the lock-to-lock rotational speed is exactly 1 rotation (360 °) as long as the visual effect of the pie chart can be obtained. For example, the steering gear ratio α / γ may be controlled so that the lock-to-lock rotation speed is within a range of 300 ° to 420 °. If it exceeds 420 °, the overlapping range of the tracks drawn by the steering wheel 11 is too wide, and it is difficult to obtain a sufficient visual effect of the pie chart. If the angle is less than 300 °, the circle of the trajectory drawn by the steering handle 11 is too short, and it is difficult to obtain a sufficient visual effect of the pie chart.

  Further, the steering gear ratio control means 62 determines that the road surface shape determining means 61 determines that the road surface shape affects the traveling direction of the vehicle, the steering gear so that the lock-to-lock rotation speed becomes approximately one rotation. The ratio α / γ may be controlled, and the steering gear ratio α / γ may be controlled to be greater near the neutral position of the steering wheel 11 than at positions other than near the neutral position.

  When the lock-to-lock rotation speed is changed from approximately 3 rotations to approximately 1 rotation, the turning angle γ reacts approximately three times more sensitively to changes in the steering angle α. Therefore, in the vicinity of the neutral position of the steering wheel 11, the change in the steering angle γ with respect to the amount of change in the steering angle α during straight traveling is controlled by largely controlling the steering gear ratio α / γ compared to the vicinity of the vicinity of the neutral position. The amount can be reduced, and even when the lock-to-lock rotation speed is approximately one rotation, the stability during straight traveling can be increased.

  If the assisting force control means 63 determines that the road surface shape determining means 61 has a road surface shape that affects the traveling direction of the vehicle, the road surface shape determining means 61 determines that the road surface shape determining means 61 does not have a road surface shape that affects the traveling direction of the vehicle. Compared with the case where it is done, the assist force of the assist mechanism 40 near the neutral position of the steering handle 11 is controlled to be small.

  When the lock-to-lock rotation speed is changed from approximately 3 rotations to approximately 1 rotation, the turning angle γ reacts approximately three times more sensitively to changes in the steering angle α. Therefore, by controlling the assist force of the assist mechanism 40 in the vicinity of the neutral position of the steering handle 11 to be small, the steering handle 11 can be made heavy during straight traveling, and the lock-to-lock rotation speed is approximately one rotation. Even in this case, stability during straight traveling can be increased.

  The assist force is controlled by setting a target value Ap of the assist force A based on the steering angle α and controlling the electric motor 41 so that the assist force A becomes the target value Ap. For setting the target value Ap of the assist force A, electronic data that defines the relationship between the steering angle α and the target value Ap stored in the ROM of the ECU 33 when the vehicle is manufactured is used.

  Here, an example of processing executed by the ECU 33 will be described with reference to a flowchart of FIG. The ECU 33 performs the processing after S11 every predetermined time, and always optimally controls the steering gear ratio α / γ.

  In S11 of FIG. 3, the ECU 33 checks whether or not the road surface shape affects the traveling direction of the vehicle.

  In S11, when the road surface shape does not affect the traveling direction of the vehicle (S11, No), the traveling direction of the vehicle is determined by the turning angle γ of the wheels 13a and 13b. For this reason, since it is not necessary to prevent misrecognition of the turning angle γ of the wheels 13a and 13b, the current process is terminated.

  If the road surface shape affects the traveling direction of the vehicle in S11 (S11, Yes), the traveling direction of the vehicle is not determined only by the turning angle γ of the wheels 13a, 13b. The steering gear ratio α / γ is controlled so that the two-lock rotation speed is 1 rotation, and the current process is terminated.

  Thereby, as described above, the turning angle γ of the wheels 13a and 13b arranged in the blind spot is easily grasped based on the steering angle α of the steering handle 11 arranged in the visual field by the visual effect of the pie chart. Even when the road surface shape affects the traveling direction of the vehicle, it is possible to prevent or suppress misidentification of the turning angle γ of the wheels 13a and 13b.

  FIG. 4 is a flowchart illustrating another example of processing executed by the ECU 33. Hereinafter, processing executed by the ECU 33 shown in FIG. 4 will be described, but the same processing as that shown in FIG.

  If the road surface shape affects the traveling direction of the vehicle in S11 (S11, Yes), the traveling direction of the vehicle is not determined only by the turning angle γ of the wheels 13a, 13b. The steering gear ratio α / γ is controlled so that the lock rotational speed is approximately one rotation, and the steering gear ratio α / γ is controlled to be greater near the neutral position of the steering handle 11 than at positions other than near the neutral position. .

  As a result, as described above, the amount of change in the turning angle γ with respect to the amount of change in the steering angle α during straight traveling can be reduced, and the lock-to-lock rotational speed is approximately one rotation. In addition, stability during straight traveling can be increased.

  Subsequently, in S22, the assist force in the vicinity of the neutral position of the steering wheel 11 is controlled to be smaller than the case where the road surface shape determining means 61 determines that the road surface shape does not affect the traveling direction of the vehicle. End the process.

  As a result, as described above, the steering handle 11 during straight traveling can be made heavier, and the stability during straight traveling can be increased even when the lock-to-lock rotational speed is approximately one rotation. be able to.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, although the assist mechanism 40 of the present embodiment assists the rotation of the input shaft 12 using the rotational torque of the electric motor 41, hydraulic pressure may be used instead of the electric motor 41. Further, instead of assisting the rotation of the input shaft 12, the reciprocating motion of the rack bar 16 may be assisted. When hydraulic pressure is used instead of the electric motor 41, the assist force control means 63 controls the assist force by controlling the hydraulic pressure.

  Further, the assist force control means 63 of this embodiment controls the assist force to be small only in the vicinity of the neutral position of the steering handle 11. However, not only in the vicinity of the neutral position of the steering handle 11, but also in all steering of the steering handle 11. The assist force may be controlled to be small at the position. Thereby, the steering wheel 11 can be made heavy, and not only the stability during straight traveling but also the stability during curve traveling can be increased.

  Further, the steering gear ratio control means 62 of the present embodiment may control the steering gear ratio α / γ larger in the vicinity of the neutral position of the steering handle 11 than in the vicinity of the neutral position. The gear ratio α / γ may be controlled to be constant. When the steering gear ratio α / γ is controlled to be constant, the change amount of the turning angle γ with respect to the change amount of the steering angle α is always constant. For this reason, based on the steering angle α of the steering handle 11, the steered angle γ of the wheels 13a, 13b can be more easily grasped.

It is the figure which showed one Example of the structure of the steering device of this invention. It is a functional block diagram showing an example of the configuration of the steering gear ratio variable mechanism 30 and connecting parts. It is the flowchart which showed an example of the process which ECU33 performs. 7 is a flowchart illustrating another example of processing executed by the ECU 33. It is the figure which showed an example of the relationship between the drive gear which comprises the conventional steering gear ratio variable mechanism, and a passive gear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Steering handle 13a, 13b Wheel 30 Steering gear ratio variable mechanism 31 Electric motor 33 ECU
DESCRIPTION OF SYMBOLS 40 Assist mechanism 41 Electric motor 61 Road surface shape determination means 62 Steering gear ratio control means 63 Assist force control means

Claims (3)

In a steering apparatus including a steering gear ratio variable mechanism that changes a steering gear ratio between a steering angle of a steering wheel and a steering angle of a wheel,
Road surface shape determining means for determining whether or not the road surface shape affects the traveling direction of the vehicle;
If it is determined by the road surface shape determining means that the road surface shape affects the traveling direction of the vehicle, it is necessary to change the wheel from one maximum turning angle state to the other maximum turning angle state. Steering gear ratio control means for controlling the steering gear ratio so that the number of rotations of the steering handle is approximately one rotation;
A steering apparatus comprising:   If the steering gear ratio control means determines that the road surface shape determining means has a road surface shape that affects the traveling direction of the vehicle, the steering gear ratio control means moves the wheel from the state of one maximum turning angle to the other maximum turning angle. The steering gear ratio is controlled so that the number of rotations of the steering handle required to achieve the state of approximately one rotation, and in the vicinity of the steering wheel in the neutral position, the steering wheel is compared with that in the vicinity of the neutral position. The steering apparatus according to claim 1, wherein the gear ratio is largely controlled. An assist mechanism for assisting steering of the steering wheel in a steering direction;
When it is determined by the road surface shape determining means that the road surface shape affects the traveling direction of the vehicle, compared to the case where the road surface shape determining means determines that the traveling direction of the vehicle is not affected by the road surface shape, Assist force control means for controlling the assist force of the assist mechanism in the vicinity of a neutral position of the steering handle;
The steering apparatus according to claim 1 or 2, further comprising:

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