JP2013127429A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device for a vehicle, capable of efficiently performing processing for setting a reference value of a detection sensor for a rear wheel steering angle.SOLUTION: In a steering device for a vehicle, a detection sensor detects a steering angle of rear wheels of the vehicle. A tentative reference value acquisition part stores a detection value of the detection sensor as a tentative reference value. A holding control part controls the detection value of the detection sensor so as to hold it at the tentative reference value. A reference setting part sets a reference value of detection means relative to a predetermined steering angle of the rear wheels. The holding control part releases holding at the tentative reference value when the setting of the reference value of the detection sensor in the reference setting part is completed.

Description

  The present invention relates to a vehicle steering device, and more particularly, to a vehicle steering device suitable for inspection before vehicle shipment.

  2. Description of the Related Art Conventionally, as a rear wheel steering device, a system is known in which a steering angle of a rear wheel is controlled by an actuator according to a steering state of a front wheel (see Patent Document 1). Patent Document 1 discloses a steering mechanism for steering a rear wheel, a motor for driving the steering mechanism, a steering angle detection sensor for detecting a steering angle of the rear wheel, and detection of a target steering angle and a steering angle detection sensor for the rear wheel. A rear wheel steering device is disclosed that includes a control unit that controls driving of the motor based on the result.

  The rear wheel steering device described in Patent Document 1 includes a potentiometer that is an absolute steering angle detection sensor and a magnetic pole sensor that is a relative steering angle detection sensor, and obtains a reference steering angle of the steering angle of the rear wheel using the potentiometer. The rotation angle of the motor is calculated from the steering angle and the output change of the magnetic pole sensor, and the steering angle is detected.

JP-A-6-278634

  By the way, in order to control the steering of the rear wheel, it is necessary to accurately set the correspondence between the detection result of the steering angle detection sensor and the steering angle of the rear wheel in advance, and the correspondence is set before vehicle shipment. The learning process is executed at the inspection site. It is preferable to make the inspection time required for this learning process as short as possible.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle steering apparatus that can efficiently perform the process of setting the reference value of the detection means for the rear wheel steering angle.

  In order to solve the above-described problem, a vehicle steering apparatus according to an aspect of the present invention includes a detection unit that detects a turning angle of a rear wheel of a vehicle, and a temporary storage that stores an arbitrary detection value of the detection unit as a temporary reference value. Reference value acquisition means, and holding control means for controlling the detection value of the detection means so as to be held at the provisional reference value.

  According to this aspect, the detection value of the detection means can be prevented from deviating from the temporary reference value, and the state of the steering angle of the rear wheels can be maintained after storing the temporary reference value. Thereby, for example, by maintaining the state of the steering angle of the rear wheels immediately after the vehicle steering device is assembled to the vehicle, the setting process of the reference value of the detection means before vehicle shipment can be executed efficiently.

  You may further provide the reference setting means which sets the reference value of a detection means with respect to the predetermined rudder angle of a rear wheel. The holding control means may release the holding at the temporary reference value when the setting of the reference value of the detecting means in the reference setting means is completed. As a result, the reference value can be set in a state where the holding control means has held it.

  The holding control means may perform control to return the detection value of the detection means to the provisional reference value when the rear wheel is steered by an external force during the holding control. Thereby, even if a rear wheel steers, it can return to an original position.

  In the initial assembly state in which the vehicle steering device is assembled to the vehicle, the steering angle of the rear wheels is substantially at the midpoint. As a result, the state where the rudder angle of the rear wheels is approximately at the midpoint can be stored as a temporary reference value.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus for vehicles which can perform the process which sets the reference value of the detection means of a rear-wheel steering angle efficiently can be provided.

1 is a diagram schematically showing a vehicle equipped with a vehicle steering device. FIG. It is a figure which shows the functional block of RR-ECU. It is a flowchart which shows provisional reference | standard setting processing.

  FIG. 1 is a diagram schematically showing a vehicle on which a vehicle steering apparatus 1 is mounted. The vehicle steering apparatus 1 for a vehicle includes a steering handle 10 that is turned by a driver. The steering handle 10 is fixed to the upper end of the steering input shaft 11, and the lower end of the steering input shaft 11 is connected to the FR actuator 21. The FR actuator 21 may be a transmission ratio variable actuator, and includes an FR motor 22 that is an electric motor and a speed reducer, and is connected to the speed reducer with respect to the rotation amount (or rotation angle) of the steering input shaft 11. The rotation amount (or rotation angle) of the steering output shaft 12 is changed as appropriate.

  The FR motor 22 has a motor housing that is integrally connected to the steering input shaft 11, and rotates integrally in accordance with a turning operation of the steering handle 10 by the driver. The drive shaft of the FR motor 22 is connected to a speed reducer, and the rotational force of the FR motor 22 is transmitted to the speed reducer via the drive shaft. The reduction gear is configured by a predetermined gear mechanism, and the turning output shaft 12 is connected to the gear mechanism at the upper end. Thus, when the rotational force of the FR motor 22 is transmitted through the drive shaft, the speed reducer decelerates the rotation of the drive shaft by the gear mechanism and transmits it to the steered output shaft 12. Therefore, the FR actuator 21 connects the steering input shaft 11 and the steered output shaft 12 via the drive shaft of the FR motor 22 so as to be relatively rotatable.

  The vehicle steering apparatus 1 includes a front wheel steering unit 40 that is a front wheel side steering mechanism connected to the lower end of the steering output shaft 12. The front wheel steering unit 40 is, for example, a gear unit adopting a rack and pinion type, and the rotation of the pinion gear integrally assembled to the lower end of the steering output shaft 12 is transmitted to the rack bar. Yes. Further, the front wheel steering unit 40 is provided with an EPS (Electric Power Steering) motor (non-electric motor) which is an electric motor for reducing the steering force (more specifically, the steering torque) input to the steering handle 10 by the driver. The torque (so-called assist force) generated by the EPS motor is transmitted to the rack bar.

  With this configuration, the rotational force of the steering output shaft 12 is transmitted to the rack bar via the pinion gear, and the assist force of the EPS motor is transmitted to the rack bar. As a result, the rack bar is displaced in the axial direction by the rotational force from the pinion gear and the assist force of the EPS motor, and the left and right front wheels FW1, FW2 connected to both ends of the rack bar are steered left and right. .

  Further, the vehicle steering apparatus 1 can steer the left and right rear wheels RW1, RW2 in relation to the steering of the left and right front wheels FW1, FW2. For this reason, the vehicle steering apparatus 1 includes a rear wheel turning unit 41 for turning the left and right rear wheels RW1 and RW2. The rear wheel turning unit 41 includes an RR actuator 31 that generates a rotational driving force for turning the left and right rear wheels RW1 and RW2, and the RR actuator 31 includes an RR motor 32 for turning the rear wheels. The RR motor 32 is a brushless motor, and a first detection sensor 33 for detecting the rotation angle of the RR motor 32 is provided. The first detection sensor 33 is a relative angle sensor that detects a rotation angle relative to a predetermined reference, and may be a resolver that detects the rotation position of the rotor of the RR motor 32. The second detection sensor 34 is an absolute angle sensor that detects an absolute stroke of the rear wheel steering unit 41 and may be a potentiometer that detects a stroke angle. The first detection sensor 33 has higher detection accuracy than the second detection sensor 34. The first detection sensor 33 and the second detection sensor 34 (referred to as a detection sensor when these are not distinguished) detect the steering angle of the rear wheels. The rear wheel steering unit 41 has a well-known gear mechanism, decelerates the rotation of the RR motor 32, converts the decelerated rotational motion into axial motion, and transmits it to the left and right rear wheels RW1, RW2.

  With this configuration, the RR motor 32 is rotationally driven according to the turning operation of the steering handle 10 by the driver, that is, in accordance with the turning of the left and right front wheels FW1 and FW2, and the rotation decelerated by the gear mechanism moves in the axial direction. Is converted to Then, this axial movement is transmitted to the left and right rear wheels RW1, RW2, and the left and right rear wheels RW1, RW are steered to the left and right.

  In the vehicle steering apparatus 1, a front control device (hereinafter referred to as “FR-ECU 20”) controls the operation of the FR actuator 21, specifically, controls the rotation of the FR motor 22, and controls the front wheels FW 1 and FW 2. The turning angle is given. The FR-ECU 20 and the FR actuator 21 constitute an FR system 25. Further, a rear control device (hereinafter referred to as “RR-ECU 30”) controls the operation of the RR actuator 31, more specifically, controls the rotation of the RR motor 32, thereby turning the rear wheels RW1 and RW2. give. The RR-ECU 30 and the RR actuator 31 constitute an RR system 35. Each ECU is configured as a microprocessor including a CPU. In addition to the CPU, each ECU includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like.

  By the way, after the vehicle is assembled, it is shipped after executing a learning process for inspecting the state of the vehicle. That is, after the vehicle assembly process is executed in the factory, the vehicle is moved to the inspection site, and the learning process is executed using the learning device provided in the inspection site. The learning process includes a reference setting process for setting a reference value for the steering angle of the rear wheels. Details of the reference setting process will be described later. For example, the reference value is set at the midpoint of the rudder angle of the rear wheel. If you do, the rear wheels go straight.

  When the midpoint of the rear wheel rudder angle is detected in the reference setting process, if the rudder angle of the rear wheel is greatly deviated from the midpoint, it takes a very long detection time. Here, when the vehicle is assembled, the RR actuator 31 and the rear wheel steering unit 41 are assembled in a neutral state in which the steering angle of the rear wheels is located at the midpoint. However, even if the vehicle is in a neutral state before movement, if the rear wheel is steered while moving to the inspection site, the steering angle of the rear wheel may deviate from the middle point, and inspection time may be required. Therefore, in the embodiment, the control for maintaining the steering angle of the rear wheels in the initial assembly state is executed from when the RR system 35 is assembled to the vehicle until the learning process is completed. Thereby, it is possible to suppress the increase in inspection time and to efficiently execute the reference setting process.

  FIG. 2 is a diagram illustrating functional blocks of the RR-ECU 30. The RR-ECU 30 includes a sensor value receiving unit 50, a provisional reference value obtaining unit 52, a holding control unit 54, a reference setting unit 56, a driving unit 58, a reference value holding unit 60, and a driving control unit 62.

  The sensor value receiving unit 50 receives the detection results from the first detection sensor 33 and the second detection sensor 34. The temporary reference value acquisition unit 52 stores any detection value of the detection sensor as a temporary reference value as it is. The provisional reference value acquisition unit 52 stores, as a first provisional reference value, an arbitrary rotational position of the rotor of the RR motor 32 detected by the first detection sensor 33 when the reference setting process is not completed. Further, the provisional reference value acquisition unit 52 stores the detection value detected by the second detection sensor 34 as the second provisional reference value when the reference setting process is not completed. When the first provisional reference value and the second provisional reference value are not particularly distinguished, they are referred to as provisional reference values. The provisional reference value may be an average value of the detection values detected by the detection sensor.

  In the initial assembly state after the RR system 35 and the rear wheel steering unit 41 are assembled to the vehicle and before the vehicle is moved to the inspection site, the steering angle of the rear wheels is substantially at the midpoint, and therefore the provisional reference value acquisition unit 52 Stores the detection value of the detection sensor in that state as a provisional reference value. Thereby, the initial assembly state can be memorized concerning the steering angle of the rear wheel. For example, when the RR system 35 is assembled to the vehicle, the ignition switch is turned on and the RR-ECU 30 is started, the provisional reference value acquisition unit 52 starts from the first detection sensor 33 to the RR motor if the reference setting process is not completed. 32 rotational positions are acquired as the first provisional reference value. The first provisional reference value is the rotational position of the RR motor 32 detected by the first detection sensor 33 in the initial assembly state. The RR motor 32 is assembled in a state corresponding to the substantially middle point of the steering angle of the rear wheels in the initial assembled state.

  The holding control unit 54 controls to hold the RR motor 32 so that the detection value of the detection sensor becomes the provisional reference value when the reference setting process is not completed. The holding control unit 54 sends to the driving unit 58 a control signal for holding the RR motor 32 from rotating by an external force transmitted from the rear wheel when the vehicle is moving. Thereby, rotation of the RR motor 32 can be fixed. The holding control unit 54 releases the holding of the RR motor 32 at the temporary rotation position at least when the reference setting process is completed. Note that the holding control unit 54 may release the holding of the RR motor 32 at the temporary rotation position when the reference setting process is started. The holding control unit 54 performs control to return the rotation position of the RR motor 32 so that the detection value of the detection sensor becomes a provisional reference value when the rear wheel is steered by an external force and the RR motor 32 rotates during the holding control. .

  Specifically, during the holding control, the holding control unit 54 controls the RR motor 32 so that the RR motor 32 does not operate with the RR motor 32 in a substantially rigid state. However, when the rotational position of the RR motor 32 changes due to an external force, The rotational position of the motor 32 is returned. That is, the holding control unit 54 performs control to return the state of the RR motor 32 to the initial assembly state stored from the provisional reference value acquisition unit 52 even when the RR motor 32 operates. For example, when the absolute value of the difference between the detection value of the detection sensor and the provisional reference value exceeds a predetermined threshold, the holding control unit 54 adjusts the RR motor 32 so that the detection value of the detection sensor becomes the provisional reference value. Control to return the rotation position. Since the operation of the ECU is unknown in the initial assembly state, generally the drive control of the RR motor 32 and the like is not executed until the learning process is completed. However, in the embodiment, the initial assembly state is limited to the RR motor 32 only. Execute drive control to maintain Thereby, since the states of the RR actuator 31 and the rear wheel steering unit 41 are substantially in the neutral position as in the initial assembly state in the reference setting process, the learning process can be executed efficiently.

  The drive unit 58 is, for example, a drive circuit that drives the RR motor 32, and supplies a drive current corresponding to control signals input from the holding control unit 54 and the drive control unit 62 to the RR motor 32.

  The reference setting unit 56 sets a reference value of the detection sensor for a predetermined steering angle of the rear wheels. The reference value of the detection sensor indicates a correspondence relationship between the detection value of the detection sensor and the steering angle of the rear wheel. For example, the reference value of the detection sensor is set to a neutral point (neutral angle) of the steering angle and set to match the neutral position of the steering wheel 10. Is done. When the RR motor 32 is rotating from the neutral angle, the reference setting unit 56 can set the reference value by correcting the RR motor 32 by forcibly driving it. When the reference value is set, the reference setting unit 56 sets a completion flag and sends the reference value information to the reference value holding unit 60. The reference value holding unit 60 holds information on the reference value set by the reference setting unit 56. The reference value information is stored in a different area from the provisional reference value information held by the provisional reference value acquisition unit 52.

  The drive control unit 62 receives the target steering angle from the FR-ECU 20 and controls the steering angle of the rear wheels. Specifically, the drive control unit 62 controls the control signal based on the detection values of the first detection sensor 33 and the second detection sensor 34, information on the reference value possessed by the reference value holding unit 60, and the target steering angle of the rear wheels. And outputs a control signal to the drive unit 58 to control the steering of the rear wheels. The drive control unit 62 controls the reference value as a neutral angle of the rear wheel steering angle.

  FIG. 3 is a flowchart showing provisional reference setting processing. The provisional reference setting process shown in the figure is periodically executed. The provisional reference value acquisition unit 52 determines whether IG (ignition switch) is turned on (S10). If the IG is not turned on (N in S10), the process ends. If the IG is turned on (Y in S10), the provisional reference value acquisition unit 52 determines whether or not the holding mode in which holding control is executed is in progress. (S12).

  If it is in the holding mode (Y in S12), the process is terminated. If it is not in the holding mode (N in S12), the provisional reference value acquisition unit 52 determines whether the reference setting process is completed (S14). If the reference setting process is completed (Y in S14), the process ends. If the reference setting process has not been completed (N in S14), the temporary reference value acquisition unit 52 acquires and stores the temporary reference value in the RR motor 32 from the first detection sensor 33 and the second detection sensor 34 (S16). Then, a holding mode flag is set (S18). The holding control unit 54 starts the holding mode control using the temporary reference value when the holding mode flag is set. If the reference setting process has been completed, the holding control unit 54 lowers the holding mode flag and ends the holding mode. Thus, the RR actuator 31 can be held in the initial assembled state until the learning process is completed, and an increase in the processing time of the reference setting process can be suppressed.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  In the embodiment, in the provisional reference setting process, an aspect in which both detection values of the first detection sensor 33 and the second detection sensor 34 are acquired as provisional reference values is shown, but the present invention is not limited to this. For example, the detection value of one sensor may be acquired as the temporary reference value, or the detection value of the first detection sensor 33 may be acquired as the temporary reference value on the assumption that the RR motor 32 is in the initial assembly state. Also in this aspect, the initial assembly state of the RR actuator 31 can be maintained until the learning process is completed.

  DESCRIPTION OF SYMBOLS 1 Steering device for vehicles, 10 Steering handle, 11 Steering input shaft, 12 Steering output shaft, 20 FR-ECU, 21 FR actuator, 22 FR motor, 25 FR system, 30 RR-ECU, 31 RR actuator, 32 RR motor 33 First detection sensor, 34 Second detection sensor, 35 RR system, 40 Front wheel steering unit, 41 Rear wheel steering unit, 50 Sensor value receiving unit, 52 Temporary reference value acquisition unit, 54 Holding control unit, 56 Standard setting Part, 58 drive part, 60 reference value holding part, 62 drive control part.

Claims (4)

Detecting means for detecting a turning angle of a rear wheel of the vehicle;
Provisional reference value acquisition means for storing the detection value of the detection means as a provisional reference value;
The vehicle steering apparatus comprising: holding control means for controlling the detected value of the detecting means to be held at the temporary reference value after the temporary reference value acquiring means stores the temporary reference value. . Further comprising reference setting means for setting a reference value of the detection means for a predetermined steering angle of the rear wheel,
2. The vehicle steering apparatus according to claim 1, wherein the holding control unit releases the holding at the temporary reference value when the setting of the reference value of the detecting unit by the reference setting unit is completed. .   3. The control according to claim 1, wherein the holding control unit performs control to return the detection value of the detection unit to the provisional reference value when the rear wheel is steered by an external force during the holding control. Vehicle steering system. In the initial assembly state in which the vehicle steering device is assembled to the vehicle, the steering angle of the rear wheel is substantially at the middle point,
4. The vehicle according to claim 1, wherein the provisional reference value obtaining unit obtains the provisional reference value when an ignition switch is turned on in the initial assembly state. 5. Steering device.

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