JP4652103B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a so-called steer-by-wire vehicle steering apparatus in which an operator operated by a driver and a steering actuator that steers a steered wheel are mechanically separated.

  In a steer-by-wire vehicle steering system, a reaction force actuator for applying an appropriate steering reaction force when the driver operates the steering wheel, and a steered wheel according to the driver's operation of the steering wheel And a steering actuator for steering the vehicle, and both actuators are independently controlled.

  In this steer-by-wire steering device, the ratio of the steering wheel operation angle to the target turning angle (hereinafter referred to as the steering ratio) can be made variable, for example, the vehicle speed increases. Therefore, a control method for gradually reducing the steering ratio is known. If the steering ratio is variably controlled according to the vehicle speed in this manner, there is an advantage that the steered wheel can be steered greatly at a low speed because the operation amount of the steering wheel is small, and the steering is stable at a high speed. In addition, when the steering ratio is variably controlled in this manner, the rotation angle (maximum rotation angle) of the steering wheel when the steering rack reaches the rack end and the steered wheels are steered to the maximum changes according to the vehicle speed. The higher the value, the larger.

However, in the steer-by-wire type steering device, the steering wheel and the steering mechanism are mechanically separated, so the steering wheel can be further increased even when the steered wheel reaches maximum steering, When this happens, it is necessary for the driver to recognize that he can no longer steer the steered wheels.
As a conventional method for recognizing the maximum turning, there is a known method of suddenly raising the thrust of the reaction force actuator so that the steering wheel cannot be further increased when approaching the maximum turning. (For example, refer to Patent Document 1).
JP 2004-130971 A

  By the way, in a vehicle, there is a case where a so-called airbag is stored in a steering wheel as an impact reducing device at the time of a collision with a driver. In this case, a cable reel electrical signal line for communicating an airbag actuation electrical signal is provided. The wiring is inserted through the steering shaft consisting of a hollow shaft. The cable reel electrical signal line has a spiral shape so as to allow twisting due to the rotation of the steering wheel. However, since the allowable range is limited, the cable reel electrical signal line is based on the maximum rotation angle of the steering wheel. The specifications are set. Therefore, conventionally, the specification of the cable reel electric signal line has to be set based on the maximum rotation angle at high speed at which the maximum rotation angle is the largest, and as a result, the size and weight of the cable reel electric signal line are reduced. growing.

In addition, in the method of recognizing the maximum turning by suddenly raising the thrust of the reaction force actuator, the thrust required to recognize the maximum turning is greater than the reaction force generated by the actuator required during normal steering. In order to recognize the maximum turning, it is necessary to increase the output of the reaction force actuator, which increases the size of the actuator.
Accordingly, the present invention provides a vehicle steering apparatus capable of reducing the size and weight of cable reel electrical signal lines and the like.
The present invention also provides a vehicle steering apparatus that can easily recognize the maximum steering without increasing the size of the reaction force actuator.

In order to solve the above-described problems, an invention according to claim 1 is directed to an operator (for example, a steering wheel 2 in an embodiment described later) that is operated by a driver, and a roller that is mechanically separated from the operator. A steering wheel (for example, a wheel 6 in an embodiment to be described later), a steering actuator for steering the steered wheel (for example, a steering motor 10 in an embodiment to be described later), and an operation amount (operation angle) of the operator are detected. An operation amount detection means (for example, an operation angle sensor 3 in an embodiment described later), a vehicle speed detection means (for example, a vehicle speed sensor 11 in an embodiment described later), and an operation detected by the operation amount detection means. Steering actuator control means for controlling the steering actuator in accordance with the amount and the vehicle speed detected by the vehicle speed detection means (for example, in the embodiments described later) A control device 13), and the ratio of the turning amount of the steered wheels with respect to the manipulated variable of the operating element is controlled to decrease as the vehicle speed increases, and the steered wheels are The maximum operation amount (maximum rotation angle), which is the operation amount of the operation element at a constant, is constant regardless of the vehicle speed, and the steered wheel with respect to the operation amount of the operation element increases as the operation amount of the operation element increases. This is a vehicle steering device (for example, a vehicle steering device 1 in an embodiment to be described later) in which the width of the change in accordance with the vehicle speed of the ratio of the steering amount is small .
With this configuration, the ratio of the steered wheel steered amount to the steered wheel manipulated variable is controlled to decrease as the vehicle speed increases. The steered wheel can be steered greatly, while the steering stability can be improved at high speeds. In addition, since the maximum operation amount (maximum rotation angle), which is the operation amount of the operator when the steered wheels are at maximum steering, is constant regardless of the vehicle speed, the maximum operation amount is one of the design conditions and specification setting conditions. design of equipment readily ing required as One.

According to a second aspect of the present invention, in the first aspect of the present invention, when the operation amount with respect to the operation element becomes a maximum operation amount, the operation amount is prevented and the operation amount is prevented from increasing beyond the maximum operation amount. And a stopper mechanism (for example, a stopper mechanism 20 in an embodiment described later).
By configuring in this way, it is possible to reliably prevent the operation element from being excessively operated beyond the maximum operation amount. Further, since the reaction force control for causing the driver to recognize the maximum steering is not required, the reaction force actuator can be reduced in size and weight.

According to the first aspect of the present invention, the steered wheel can be steered greatly with a small amount of operation of the operator at low speeds, while the steering stability can be improved at high speeds. In addition, it becomes easy to design a device that requires the maximum operation amount as one of design conditions and specification setting conditions.
According to the second aspect of the present invention, it is possible to reliably prevent the operation element from being excessively operated beyond the maximum operation amount, and to reduce the size and weight of the reaction force actuator.

Hereinafter, an embodiment of a vehicle steering apparatus according to the present invention will be described with reference to the drawings of FIGS.
As shown in FIG. 1, the vehicle steering apparatus 1 includes a steering wheel (operator) 2 that is operated by a driver, a steering shaft 14 that is connected to the steering wheel 2 and that is a hollow shaft that rotates synchronously, and a steering wheel. An operation angle sensor (operation amount detection means) 3 that detects an operation angle (operation amount) of the wheel 2, a reaction force motor (reaction force actuator) 4 that applies an operation reaction force to the steering wheel 2 via the steering shaft 14, and , An operation torque sensor 5 for detecting an operation torque acting on the steering shaft 14, a rack shaft 9 connected to left and right wheels (steered wheels) 6 via a knuckle arm 7 and a tie rod 8, and an axial direction of the rack shaft 9 A steering motor (steering actuator) 10 that steers the wheel 6 by driving the vehicle and a vehicle speed sensor that detects the vehicle speed (Vehicle speed detection means) 11, a turning angle sensor (steering angle detection means) 12 that detects the turning angle of the wheel 6 from the axial position of the rack shaft 9, and a control that controls the reaction force motor 4 and the steering motor 10. And a device (steering actuator control means) 13.

In the steering device 1, the reaction force motor 4 and the steering motor 10 are individually controlled by the control device 13.
Specifically, the control device 13 sets the target turning angle based on the operation angle signal including the operation direction (rotation direction) of the steering wheel 2 from the operation angle sensor 3 and the vehicle speed signal from the vehicle speed sensor 11. Then, the power supplied to the steering motor 10 is controlled so that the output value of the turning angle sensor 12, that is, the actual turning angle of the wheel 6 coincides with the target turning angle. As a result, the optimum turning angle of the wheel 6 is determined in consideration of the vehicle speed at that time with respect to the operation angle (operation amount) given to the steering wheel 2 by the driver.

  The control device 13 sets a target operation reaction force based on the vehicle speed signal from the vehicle speed sensor 11, the turning angle signal from the turning angle sensor 12, and the like, and the output of the operation torque sensor 5 is set to this target operation reaction force. The power supplied to the reaction force motor 4 is controlled so that the values (that is, the actual operation torque) match. As a result, an operation reaction force opposite to the operation direction of the steering wheel 2 by the driver is applied to the steering wheel 2, and steering as if a torsion bar exists between the steering wheel 2 and the wheel 6. Feeling can be obtained.

By the way, in this steering device 1, the ratio of the operation angle of the steering wheel 2 to the target turning angle, that is, the steering ratio is variably controlled, and control is performed so that the steering ratio gradually decreases as the vehicle speed increases. The steering motor 10 is controlled by the device 13. Thereby, the amount of operation of the steering wheel is small at low speed, and the steered wheel can be steered greatly, and the steering stability at high speed can be improved.
However, in the steering apparatus 1 of this embodiment, the maximum rotation angle of the steering wheel 2 is constant regardless of the vehicle speed. More specifically, the rack shaft 9 has its maximum stroke restricted by the rack end abutting against a stopper (none of which is shown), and the turning angle of the wheel 6 is maximum (that is, maximum turning) at that position. However, the operation angle of the steering wheel 2 at the time of maximum steering, that is, the maximum rotation angle (maximum operation amount) is constant regardless of the vehicle speed, and the value is based on the steering ratio at the low vehicle speed. The maximum rotation angle is set.

  FIG. 4 is an example of the steering characteristics with the vehicle speed as a parameter, the operation angle of the steering wheel 2 on the horizontal axis, and the reciprocal of the steering ratio on the vertical axis. In the case of this example, the maximum rotation angle is set to 540 degrees, and if the steering wheel 2 is rotated 540 degrees clockwise or counterclockwise from the neutral position (position where the vehicle goes straight) regardless of the vehicle speed, the wheel 6 is the maximum steering. The numerical value of the maximum rotation angle of 540 degrees is an example and is not limited to this.

  The steering device 1 also includes a stopper mechanism that prevents further rotation of the steering wheel 2 when the steering wheel 2 reaches the maximum rotation angle. As shown in FIGS. 2 and 3, the stopper mechanism 20 is provided on the steering shaft 14 and a steering column housing 15 through which the steering shaft 14 is inserted, and spirally formed on a part of the outer peripheral surface of the steering shaft 14. The guide groove 14a is formed, the guide hole 15a is linearly formed in the steering column housing 15 along the axial direction, and the slider 16 is detachably attached to the guide hole 15a. ing. Further, the tip 16b of the pin 16a of the slider 16 penetrating the guide hole 15a is inserted into the guide groove 14a, and when the steering wheel 2 is rotated to rotate the steering shaft 14, the pin 16a of the slider 16 becomes the guide groove 14a. As a result, the slider 16 moves linearly along the guide hole 15a. When the pin 16a hits the end of the guide hole 15a and the slider 16 is prevented from moving in the axial direction, the steering shaft 14 is prevented from further rotation. Here, the position and the axial length of the guide hole 15a are set in advance so that the steering wheel 2 has the maximum rotation angle at the position where the pin 16a hits the end of the guide hole 15a.

According to this steering device 1, the maximum rotation angle of the steering wheel 2 is constant regardless of the vehicle speed, and is the maximum rotation angle set based on the steering ratio at the low vehicle speed. Therefore, it becomes easy to design a device necessary as one of design conditions and specification setting conditions.
For example, a driver's airbag (not shown) is accommodated in the steering wheel 2 and a cable reel electrical signal line (not shown) for communicating an airbag actuation electrical signal is inserted into the steering shaft 14. In the case of wiring, when the specification of the cable reel electric signal line is determined, it can be determined based on the single maximum rotation angle. As a result, the cable reel electrical signal line can be shortened and reduced in weight.

  In other words, when the maximum rotation angle differs according to the vehicle speed as in the past, the largest maximum rotation angle (high speed when the steering ratio is controlled to gradually decrease as the vehicle speed increases). It is necessary to determine the specifications of the cable reel electric signal line based on the maximum rotation angle at the time, and this causes an increase in the length and weight of the cable reel electric signal line. This can be avoided.

Moreover, in this steering apparatus 1, the maximum rotation angle is obtained at the position where the pin 16a of the slider 16 abuts against the end of the guide hole 15a of the steering column housing 15, and the pin 16a is locked to the end of the guide hole 15a. Thus, further rotation of the steering wheel 2 is prevented, so that it is possible to reliably prevent the actual use state of the cable reel electric signal line from falling into a state exceeding the specification set as described above.
Further, the driver can recognize that the wheel 6 has been turned to the maximum when the pin 16a is locked to the end portion of the guide hole 15a and the steering wheel 2 cannot be rotated. Therefore, the reaction force control for making the driver recognize the maximum turning is unnecessary, and the reaction force motor 4 can be reduced in size and weight.

[Other Examples]
The present invention is not limited to the embodiment described above.
For example, the operation element may be a stick type instead of the steering wheel.
Also, the structure of the stopper mechanism is not limited to that described above, and any structure can be used as long as over-operation (over-rotation) of the operating element beyond the maximum rotation angle can be prevented by mechanical locking and engagement. It doesn't matter.

It is a schematic block diagram in one Example of the vehicle steering device which concerns on this invention. It is sectional drawing of the stopper mechanism in the steering apparatus for vehicles of the said Example. It is a top view of the stopper mechanism. It is a steering characteristic figure which shows vehicle speed as a parameter in the steering device for vehicles of the said Example.

Explanation of symbols

1 Vehicle steering device 2 Steering wheel (operator)
3 Operation angle sensor (operation amount detection means)
6 wheels (steering wheels)
10 Steering motor (steering actuator)
11 Vehicle speed sensor (vehicle speed detection means)
13 Control device (steering actuator control means)
20 Stopper mechanism

Claims (2)

An operator operated by the driver, and
A steered wheel mechanically separated from the operating element;
A steering actuator for steering the steered wheels;
An operation amount detecting means for detecting an operation amount of the operation element;
Vehicle speed detection means for detecting the vehicle speed;
A turning actuator control means for controlling the turning actuator in accordance with the operation amount detected by the operation amount detection means and the vehicle speed detected by the vehicle speed detection means;
The ratio of the amount of turning of the steered wheel to the amount of operation of the manipulator is controlled so as to decrease as the vehicle speed increases, and the manipulator when the steered wheel becomes maximum steered The maximum operation amount, which is the operation amount of the steering wheel, is constant regardless of the vehicle speed, and according to the vehicle speed of the ratio of the turning amount of the steered wheels to the operation amount of the operation member as the operation amount of the operation member increases. A vehicle steering system characterized in that the range of change is reduced . The vehicle according to claim 1, further comprising a stopper mechanism that is locked when an operation amount with respect to the operation element becomes a maximum operation amount and prevents the operation amount from increasing beyond the maximum operation amount. Steering device.

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