JP2010167842A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To visually stress a fact that automatic parking control is in operation so as to enable a driver to recognize it easily even on a steering ratio variable control vehicle equipped with a VGS apparatus. <P>SOLUTION: A vehicular steering device 1 includes: a steering wheel 2, which is used by a driver for steering operation; a steering system, which steers front wheels 10 by transmitting an steering input to the steering wheel 2 to front wheels 10; the VGS apparatus 4, which is interposed in the steering system and controls steering ratio of the front wheels 10 variably to the operation amount of the steering wheel 2; and an automatic parking controller 13, which steers the front wheels 10 to perform automatic parking of an vehicle V to a predetermined parking position based on the operation of an automatic parking button 14 by the driver. On the operation of the controller 13, the target steering ratio Rt of the VGS apparatus 4 is set smaller than a case where the automatic parking controller 13 is not operated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus including a variable steering ratio control apparatus that can change a steering ratio of a steering wheel with respect to an operation amount of a steering wheel.

  In recent years, a variable gear ratio steering (hereinafter abbreviated as VGS) which can variably control the steering ratio of the steering wheel with respect to the amount of operation of the steering wheel in a steering system in which the steering wheel and the steering wheel are mechanically coupled. Vehicles equipped with the device have been put on the market. As the mechanism of the VGS device, those described in Patent Documents 1 and 2 are known. In general, in a vehicle equipped with such a VGS device, the steering ratio is variably controlled according to the vehicle speed and the steering operation amount. . For example, when driving at low speeds such as when starting or entering a garage, the steering ratio is set to a large value, and even with a small steering operation, the turning angle of the tire (steering angle) is increased, thereby improving handling characteristics and a small turning radius. When turning at a steering angle, the steering ratio is set to be smaller as the steering operation amount is larger, and the operation amount and the response are increased, thereby improving the operational feeling and response.

  On the other hand, various automatic parking control devices have been proposed in which a driver parks a vehicle at a parking position without performing a steering operation by performing steering control of a steering wheel using an actuator of a known electric power steering device. (For example, see Patent Document 3). In this automatic parking control device, a CCD sensor is provided in the vehicle in order to grasp the parking position, the parking position is specified from an obstacle detected by the CCD sensor, and the steering angle is determined from the relative positional relationship with respect to the parking position of the vehicle. Automatic parking control etc. which control are known (refer to patent documents 4).

JP 2001-138951 A JP 2003-294091 A Japanese Patent Laid-Open No. 03-74256 JP 05-143895 A

  In such an automatic parking control device, the steering wheel is steered to a desired steering angle by driving the actuator of the electric power steering device. The steering wheel automatically rotates in response to steering of the steering wheel by the automatic parking control except for a vehicle that is not present. However, in a steering ratio variable control vehicle equipped with a VGS device, since the steering ratio during low-speed driving is set to be large, even if automatic parking control is performed, the rotational operation of the steering wheel becomes smaller than that of a normal vehicle, and the driver It is hard to be recognized.

  The present invention has been made in view of such a background, and even in a steering ratio variable control vehicle equipped with a VGS device, it is visually emphasized that the automatic parking control is performed, and the driver recognizes it. The purpose is to make it easier.

  In order to solve the above-described problems, a vehicle steering apparatus (1) according to the present invention includes a steering member (2) used for a driver's steering operation, and a steering input to a steering wheel (2). 10) and steering force transmission means (3-9) for steering the steering wheel (10) and steering force transmission means (3-9), and the steering wheel for the operation amount of the steering member (2). Based on the steering ratio variable control means (4) for variably controlling the steering ratio (Rt) of (10) and the automatic parking command by the driver, in order to automatically park the vehicle (V) at a predetermined parking position ( The automatic parking control means (13) for steering 10) is provided, and the steering ratio variable control means (4) is operated when the automatic parking control means (13) is not activated when the automatic parking control means (13) is activated. The steering ratio (Rt) is made smaller than that.

  According to the present invention, since the steering ratio is set small when the automatic parking control means is operated, the amount of operation of the steering member is larger than when the automatic parking control means is not operating. Therefore, even if the steering amount of the steering wheel is small, the driver can easily visually recognize that automatic parking control is being performed. Further, since the operation amount of the steering member is increased, it is possible to make the driver feel that the large operation load required for parking is reduced by the automatic parking control means, and to increase the commercial value for the vehicle steering device. it can.

Schematic diagram of an automobile provided with a vehicle steering apparatus according to an embodiment The block diagram of the steering device for vehicles concerning an embodiment The flowchart which shows the procedure of the steering ratio control which concerns on embodiment

  Hereinafter, a vehicle steering apparatus 1 according to an embodiment will be described in detail with reference to the drawings.

  First, a schematic configuration of an automobile V to which the vehicle steering device 1 is applied will be described with reference to FIG. As shown in FIG. 1, the vehicle V is equipped with a vehicle steering device 1 that steers the front wheels 10 (steering wheels) in accordance with the steering operation of the steering wheel 2 (steering member) by the driver. An input shaft 3a of a steering shaft 3 whose lower end is mechanically coupled to the rack and pinion mechanism 6 is integrally coupled to the steering wheel 2 coaxially. The input shaft 3a and the output shaft on the rack and pinion mechanism 6 side are integrally coupled. A VGS device 4 capable of changing a transmission ratio between the rotation amount of the input shaft 3a and the rotation amount of the output shaft 3b is interposed between the rotation shaft 3b and the rotation shaft 3b.

  Since the VGS device 4 is a well-known mechanism, a detailed configuration is not shown, but is a differential gear type and supports the input shaft 3a and the output shaft 3b of the steering wheel 2 so as to be relatively rotatable. VGS motor 5 and VGS motor 5 for driving and controlling VGS motor 5 having a carrier, a pair of pinion shafts provided on the carrier, a worm wheel provided on the carrier, and a worm gear meshing with the worm wheel on its output shaft A control unit 20 and the like, and by driving the VGS motor 5 and rotating the carrier in a desired direction at a desired speed, the ratio between the rotation amount of the input shaft 3a and the rotation amount of the output shaft 3b, that is, The steering ratio of the front wheels 10 with respect to the operation amount of the steering wheel 2 can be arbitrarily changed.

  The rack and pinion mechanism 6 is composed of a pinion 7 on the steering shaft 3 side and a rack shaft 8 on which rack teeth 8 a meshing with the pinion 7 are formed. The rack and pinion mechanism 6 is input from the steering wheel 2 and changes the rotation ratio by the VGS device 4. The rotational motion of the output shaft 3b thus converted is converted into a linear motion in the axial direction (vehicle width direction) of the rack shaft 8. Left and right front wheels 10 are connected to both ends of the rack shaft 8 via tie rods 9, and the front wheels 10 are steered left and right by the reciprocating linear motion of the rack shaft 8.

  The rack shaft 8 is provided with an electric power steering (hereinafter abbreviated as EPS (Electric Power Steering)) device 11 for reducing the steering operation force of the driver. The EPS device 11 includes a steering assist EPS motor 12 coaxially installed at an intermediate portion of the rack shaft 8 and an EPS control unit 30 that drives and controls the EPS motor 12. An auxiliary steering torque is applied to the rack shaft 8.

  In addition, the vehicle V automatically parks the vehicle V at a predetermined parking position by steering the front wheel 10 using the EPS motor 12 by the driver operating the automatic parking button 14 provided on the instrument panel. A control device 13 is provided. The automatic parking control device 13 includes an automatic parking button 14 provided for a driver's command, an automatic parking control unit 40 having an automatic parking program, a CCD camera 15 provided for detecting an obstacle during parking control, and the like. I have.

  Further, the vehicle V detects the steering angle sensor 16 that detects the steering angle θs of the steering wheel 2, the steering torque sensor 17 that detects the steering torque Ts that acts on the steering shaft 3 by the driver's steering operation, and the vehicle speed V. A vehicle speed sensor 18 or the like is provided in place.

  The VGS control unit 20, the EPS control unit 30, and the automatic parking control unit 40 are composed of a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, etc., and a communication line (in this embodiment, CAN ( Connected to each sensor 16-18, each control unit 20, 30, 40 and a main ECU (Electronic Control Unit) (not shown) that performs overall control of the vehicle via a controller area network)). Yes.

  As shown in FIG. 2, the EPS control unit 30 includes a target steering torque setting unit 31 that sets a target steering torque based on the detection signals θs, Ts, and V of the sensors 16 to 18 that are input via the input interface. Based on the set target steering torque, a target current setting unit 32 that sets a target current to flow to the EPS motor 12, and an output current control unit that controls an output current to the EPS motor 12 based on the set target current 33.

  The automatic parking control unit 40 switches the driving mode based on the driving mode signal Sm of the EPS motor 12 input from the automatic parking button 14 and outputs the driving mode signal Sm to the EPS control unit 30 and the VGS control unit 20. A drive mode switching unit 41, a drive mode signal Sm, a target rudder angle setting unit 42 that sets a target rudder angle of the front wheels 10 according to the video signal Sv from the CCD camera 15, and the EPS motor 12 to drive the front wheels 10 And a target current setting unit 43 that sets a target current required to steer to the set target steering angle and outputs the set target current to the output current control unit 33.

  The drive mode includes a normal mode that outputs only steering assist torque and an automatic parking mode. The automatic parking mode further includes a left mode and a right mode for back parking and parallel parking, respectively. Then, the target rudder angle setting unit 42 refers to a table in which the relationship of the standard steering angle with respect to the travel distance of the vehicle V is stored in advance for each mode, and avoids an obstacle detected from the video signal Sv. Set the corner.

  The VGS control unit 20 sets the target steering ratio setting for setting the target steering ratio Rt of the front wheels 10 according to the detection signals θs and V of the steering angle sensor 16 and the vehicle speed sensor 18 and the drive mode signal Sm input via the input interface. Unit 21, a target current setting unit 22 for setting a target current to be supplied to the VGS motor 5 based on the set target steering ratio Rt, and an output current for the VGS motor 5 based on the set target current. And an output current control unit 23.

  The target steering ratio setting unit 21 sets the target steering ratio Rt according to the vehicle speed V and the steering angle θs in the normal mode in which the automatic parking button 14 is not operated by the driver and the vehicle travels normally. While being operated by the driver and automatic parking control is being performed, the target steering ratio Rt is set to the minimum value.

Next, the target steering ratio setting process by the target steering ratio setting unit 21 will be described with reference to FIG. The target steering ratio setting unit 21 first determines whether or not the drive mode signal Sm from the automatic parking control unit 40 is the automatic parking mode, that is, whether or not the automatic parking system is ON (step 1). . When the determination in step 1 is No, the target steering ratio setting unit 21 sets the target steering ratio Rt in the normal mode according to the vehicle speed V and the steering angle θs. In the normal mode, the target steering ratio Rt is set to be relatively large at low vehicle speeds and relatively small at high vehicle speeds, and relatively small at medium vehicle speeds as the steering angle θs of the steering wheel 2 is large. The

  On the other hand, when the determination in step 1 is Yes, the target steering ratio setting unit 21 sets the target steering ratio Rt to the minimum value (step 3). Then, the target steering ratio setting unit 21 outputs the target steering ratio Rt set in step 2 or step 3 to the target current setting unit 22 (step 4) and repeats this process.

  Thus, even when the steering angle of the front wheels 10 steered by the automatic parking control unit 40 is small by setting the target steering ratio Rt to the minimum value when the automatic parking system is operating, the normal mode is set. Compared to the case, the rotation angle of the steering wheel 2 becomes larger. Accordingly, the driver can easily visually recognize that the automatic parking control is being performed. Further, since the rotation angle of the steering wheel 2 is increased, the driver can realize that the large operation load required for parking is reduced by the automatic parking control device 13, and the commercial value for the vehicle steering device 1 can be increased. Can be increased.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in the above-described embodiment, a differential gear type transmission mechanism is employed as the steering ratio variable control means. However, the present invention is not limited to this, and other types of transmission mechanisms may be employed. In the above embodiment, when the automatic parking system is operating, the target steering ratio Rt is set to the minimum value, but the target steering ratio Rt does not necessarily need to be set to the minimum value, and the normal mode It is only necessary to set a smaller value than in the case of. In addition, as long as it does not deviate from the gist of the present invention, the specific configuration of the automobile and each control device, the specific procedure of control, and the like can be appropriately changed.

1 Steering device for vehicle 2 Steering wheel (steering member)
3 Steering shaft 4 VGS device (steering ratio variable control means)
5 VGS motor 6 Rack & pinion mechanism 8 Rack shaft 10 Front wheel (steering wheel)
DESCRIPTION OF SYMBOLS 11 EPS apparatus 12 EPS motor 13 Automatic parking control apparatus 21 Target steering ratio setting part Rt Target steering ratio V Automobile

Claims (1)

A steering member used for a driver's steering operation;
Steering force transmission means for transmitting a steering input to the steering member to a steering wheel to steer the steering wheel;
Steering ratio variable control means that is interposed in the steering force transmission means and variably controls the steering ratio of the steering wheel with respect to the operation amount of the steering member;
Automatic parking control means for steering the steering wheel in order to automatically park the vehicle at a predetermined parking position based on an automatic parking command by the driver;
The vehicle steering apparatus according to claim 1, wherein when the automatic parking control means is activated, the steering ratio variable control means makes the steering ratio smaller than when the automatic parking control means is not activated.

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