JPH11301509A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the steering feeling during turning to the left and right. SOLUTION: When a turn indicator is operated (S4) and the vehicle is traveling at a low vehicle speed V of 50 km/h or less (S7), steering is regarded to be performed for left or right turns. Then, steering assist power is increase- corrected (S8) by using a blinker constant Cw which is a constant for increase- correcting the steering assist power during left or right turns. At a high vehicle speed V exceeding 50 km/h, turn indicator operation is regarded for lane changes or the like and the steering assist power is not increase-corrected (S7, S5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for applying a steering assisting force to a steering mechanism of a vehicle by using a rotational force of a motor.

[0002]

2. Description of the Related Art Many electric power steering devices mounted on four-wheel vehicles employ a vehicle speed sensitive control for increasing or decreasing a steering assist force according to a vehicle speed. That is, when the vehicle is stopped or running at low speed, the steering resistance is large, so that a relatively large steering assist force is applied to the steering mechanism. When the vehicle is running at high speed, the steering resistance is small, so that a relatively small steering assist force is applied to the steering mechanism. Has become.

[0003]

However, when turning right or left, it is necessary to make a large turn of the steering wheel, so that the steering assist force may be insufficient due to the vehicle speed sensitive control, and a sense of resistance may occur. That is, when turning right or left, the vehicle speed sensitive control may hinder a comfortable steering feeling.

An object of the present invention is to solve the above-mentioned technical problems and to provide an electric power steering device capable of improving the steering feeling when turning right or left.

[0005]

According to a first aspect of the present invention, there is provided a vehicle having a turn indicator, the steering assisting force being provided by utilizing the rotational force of a motor. Detecting means for detecting the operation / non-operation of the turn signal of the vehicle, and increasing the steering assist force when the detection means detects that the turn signal is operating. And a motor control means for controlling the motor to correct the electric power.

According to the above arrangement, when the driver operates the turn signal for turning right or left, this is detected by the detecting means. Then, based on this detection result, motor control for increasing the steering assist force is performed. As a result, when turning right or left, a larger steering assist force is applied to the steering mechanism than when the direction indicator is not operating. Therefore, even when the vehicle speed sensitive control is being performed, no resistance is generated. As a result, the steering feeling can be improved.

According to a second aspect of the present invention, there is provided a vehicle speed detecting means for detecting a vehicle speed, and a means for inhibiting an increase correction of the steering assist force when the vehicle speed detected by the vehicle speed detecting means exceeds a predetermined value (FIG. 2). 2. The electric power steering apparatus according to claim 1, further comprising: (NO in step S7 and step S5).

According to this configuration, when the vehicle speed exceeds a predetermined value, that is, when the vehicle is traveling at a relatively high speed, the correction of the increase in the steering assist force is prohibited. Accordingly, when the turn signal is operated for a purpose other than a right turn or a left turn, such as when changing lanes, the steering assist force is not increased, and unnecessary control is not performed, and stable operation is not performed. Steerability can be secured.

[0009]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an electric configuration of an electric power steering apparatus according to an embodiment of the present invention, together with a sectional structure of a steering mechanism. The steering mechanism 1 includes a rack 11 arranged along the vehicle width direction.
A pinion shaft 12 having a pinion at its tip for meshing with the rack 11 in a gear box 17, and a tie rod 13 rotatably connected to both ends of the rack 11.
And a knuckle arm 14 rotatably connected to the tip of the tie rod 13. Knuckle arm 1
The knuckle arm 14 is provided with a steering wheel (usually a front wheel) 1.
6 is attached. The base end of the pinion shaft 12 is
It is connected to a steering shaft via a universal joint, and a steering wheel is fixed to one end of the steering shaft (both are not shown). With this configuration, when the steering wheel is rotated, the rack 11 is displaced in the longitudinal direction, the knuckle arm 14 rotates around the king pin 15, and the direction of the steered wheels 16 changes.

An electric power steering device 2 for applying a steering assist force to the steering mechanism 1 includes a rack 1
1 includes a three-phase brushless motor M provided in connection with an intermediate portion of the motor 1 and a controller 20 (motor control means) for controlling the driving of the motor M via a motor driver 21. The controller 20 includes a vehicle speed sensor 22 for detecting a vehicle speed and a torque sensor 2 for detecting a steering torque.
3, and output signals of a motor rotation angle sensor 24 for detecting the rotation angle of the motor M and a direction indicator sensor 25 (detection means). These sensors 22, 23, 2
The controller 20 controls the drive current of the motor M on the basis of the output signals of the motors 4 and 25, thereby increasing or decreasing the steering assist force applied to the steering mechanism 1.

The vehicle speed sensor 22 is realized, for example, by a wheel speed sensor provided in connection with a wheel and outputting a pulse signal at a cycle corresponding to the rotation speed of the wheel. In this case, the vehicle speed, which is the speed of the vehicle, can be obtained by measuring the period or frequency of the pulse signal.

The torque sensor 23 is connected to the steering shaft by the input shaft on the steering wheel side and the pinion shaft 12.
This is realized by a configuration in which the input shaft and the output shaft are connected to each other with a torsion bar, and the amount of twist of the torsion bar is detected. That is, since the torque applied to the steering wheel and the amount of torsion of the torsion bar correspond one-to-one, the steering torque can be detected by detecting the amount of torsion with an appropriate detection mechanism such as a potentiometer.

The motor rotation angle sensor 24 comprises a rotary encoder or the like, and detects the position or displacement of the rack 11 in the vehicle width direction by detecting the rotation angle of the motor M.
This makes it possible to detect the steering angle or the amount of change in the steering angle.

The turn signal sensor 25 outputs a turn signal operation signal when the turn signal of the vehicle is operated. The direction indicator sensor 25 may use, for example, an output signal from a relay that becomes conductive during operation of the direction indicator.

The configuration related to the motor M will be briefly described. A screw shaft portion 31 is formed in the middle of the rack 11, and a ball nut 32 is screwed onto the screw shaft portion 31 via a plurality of balls. And thus a ball screw mechanism 30 is formed. The rack 11 passes through the center of the motor M. A rotor 41 of the motor M is arranged so as to surround the rack 11, and a stator 42 of the motor M is arranged so as to surround the rotor 41. Then, the rotor 41 and the ball nut 32
And are connected.

The motor M case 40 and the ball nut 32
Between them, bearings 35 and 36 are interposed, and between the case 40 and the vicinity of one end of the rotor 41, a bearing 37 is interposed. The motor rotation angle sensor 24 is disposed at the one end of the rotor 41.

With this configuration, when the motor M is energized and torque is applied to the rotor 41, the torque is transmitted to the ball nut 32 connected to the rotor 41. This torque is converted by the ball screw mechanism 30 into a driving force of the rack 11 in the vehicle width direction. Thus, the steering assist force using the motor M as a drive source is given to the steering mechanism 1.

FIG. 2 shows the motor M by the controller 20.
6 is a flowchart for explaining a process for the control of FIG. First, the controller 20 captures the output signals of the torque sensor 23 and the vehicle speed sensor 22, and collects data on the steering torque T and the vehicle speed V (Steps S1 and S2). Next, the controller 20 determines the vehicle speed V
The vehicle speed coefficient Cv is obtained based on the above (Step S3).

The vehicle speed coefficient Cv is shown in FIG.
As shown by 0, it is determined according to the vehicle speed V, and is set to a smaller value as the vehicle speed V increases.
Actually, for example, the vehicle speed V = 5, 10, 30, 80
(Km / h) of the vehicle speed coefficient Cv
The vehicle speed coefficient Cv for the vehicle speed V other than these values is calculated by a calculation such as a linear interpolation process. However, in the example of FIG. 3, the vehicle speed coefficient Cv for a vehicle speed V of less than 5 (km / h) is uniformly set to 100, and the vehicle speed coefficient Cv for a vehicle speed V of more than 80 (km / h) is uniformly set to 10. Have been.

When the vehicle speed coefficient Cv is determined, the controller 2
0 checks whether or not a turn signal operation signal is output from the turn signal sensor 25 (step S in FIG. 2).
4). If the direction indicator operation signal has not been output, a steering assist force is determined based on the following equation (1) (step S5), and a control signal for achieving the steering assist force is sent to the motor driver 21. Input (step S6).
Thereafter, the processing from step S1 is repeatedly performed.

(Steering assist force) = Cv × (Auxiliary force according to T) (1) The assist force according to the steering torque T is a table of the steering torque T and the assist force (torque− This is stored in the memory 20M in the controller 20 as an auxiliary force table), and the larger the steering torque T, the higher the auxiliary force is associated. When the steering torque T is smaller than a certain value, the auxiliary force is set to zero. The range of the steering torque T in which the assisting force is zero is generally called a dead zone.

It will be understood that by determining the steering assist force according to the above equation (1), a vehicle speed sensitive steering assist force control can be performed.

On the other hand, when the direction indicator operation signal is output (step S4), the controller 2
If it is 0, it is determined whether the vehicle speed V is 50 (km / h) or less (step S7). If the vehicle speed V exceeds 50 (km / h), the process proceeds to step S5, and the steering assist force is determined in the same manner as when no turn signal operation signal is output.

On the other hand, if it is determined in step S7 that the vehicle speed V is equal to or less than 50 (km / h), the controller 20 calculates the vehicle speed V based on the following equation (2) using the turn signal constant Cw. A steering assist force is determined (step S8), and a control signal for achieving the steering assist force is input to the motor driver 21 (step S6). Thereafter, the processing from step S1 is repeatedly performed.

(Steering assist force) = Cw × Cv × (Assistance force according to T) (2) The assist force according to the steering torque T is the same as in the case of the formula (1). It is. Also, in the case of the equation (2), since the steering assist force is determined according to the vehicle speed coefficient Cv, it will be understood that the steering assist force control adaptive to the vehicle speed is performed.

The turn signal constant Cw is a constant for increasing and correcting the steering assist force when turning right or left.
For example, Cw = 1.1. As a result, when turning right or turning left, a steering assist force that is about 10% larger than when the direction indicator is not operating is generated. A curve L1 in FIG. 3 represents the relationship between the product of the turn signal constant Cw and the vehicle speed coefficient Cv and the vehicle speed V.
In the range where the vehicle speed V exceeds 50 (km / h), Cw =
1, and in this vehicle speed region, the curve L0
And the curve L1 match. The upper limit of the product of the turn signal constant Cw and the vehicle speed coefficient Cv is set to 100. In a low-speed region, Cw × Cv in the equation (2) is fixed to 100. Note that the turn signal constant Cw may be variable. In step S7, the use of the turn signal constant Cw is based on the condition that the vehicle speed V is equal to or less than 50 (km / h) when the turn signal is operated to change lanes during high-speed driving. This is to prevent the increase in the assisting force from being corrected.

As described above, in this embodiment, whether the vehicle makes a right turn or a left turn is determined by the low-speed running state (50).
(Km / h or less), it is determined based on whether or not the direction indicator has been actuated, and when the vehicle turns right or left, the steering assist force is increased and corrected. As a result, the insufficient steering assist force at the time of turning right or left, which has conventionally been a problem in the vehicle-sensitive control, can be eliminated, and the steering feeling can be remarkably improved.

FIG. 4 is a flowchart for explaining control processing according to another embodiment of the present invention. In the description of this embodiment, the above-described FIG. 1 will be referred to again. In FIG. 4, steps in which the same processes as those in FIG. 2 are performed will be denoted by the same reference numerals as in FIG. I do.

In this embodiment, the memory 20M of the controller 20 has a first torque-auxiliary force table T1 in which the dead band width is set to a standard value, and a second torque-intensity table T1 in which the dead band width is set wider than the standard value. The auxiliary force table T2 is stored.

Then, the controller 20 determines in step S
Subsequent to the processing of step 2, it is determined whether the vehicle speed V is equal to or less than 50 (km / h) (step S11). If the vehicle speed V is 5
When the speed is equal to or less than 0 (km / h), the first torque-auxiliary force table T1 is selected (step S12), and the vehicle speed V becomes 50.
If it exceeds (km / h), the second torque-auxiliary force table T2 is selected (step S13).

Thereafter, as in the case of the above-described first embodiment, the processes in and after step S3 are performed, but in steps S5 and S8, steps S11 to S8 are performed.
The auxiliary force corresponding to the steering torque T is determined based on the torque-auxiliary force table T1 or T2 selected by the process of step 13. However, step S in FIG.
7 is omitted in this embodiment.

As described above, according to this embodiment, when the vehicle is traveling at a relatively high speed, the dead zone width is widened. Therefore, even if the direction indicator is operated and the steering operation is performed. If the steering torque T does not reach a relatively large threshold value corresponding to the dead zone of the second torque-assistance force table T2, the steering assist is not started. Thus, it is possible to prevent a large steering assist force from being applied to the steering mechanism 1 when changing lanes.

Although the two embodiments of the present invention have been described, the present invention can be implemented in other embodiments. For example, in the above-described embodiment, the electric power steering device that transmits the rotational force generated by the three-phase brushless motor M to the steering mechanism 1 has been described. However, the present invention drives the hydraulic pump by the motor,
The present invention can also be applied to an electric pump type power steering apparatus configured to assist steering by the hydraulic pressure generated by the hydraulic pump.

In addition, the torque-auxiliary force table is selectively used depending on whether the direction indicator is operating or not.
In the torque-auxiliary force table used when the direction indicator is operating, an auxiliary force value obtained by multiplying the turn signal constant Cv in advance may be associated with each value of the steering torque T.

Furthermore, in the above-described embodiment, the vehicle speed-sensitive electric power steering device has been described. However, the present invention can be applied to a vehicle speed-insensitive electric power steering device. , The steering feeling can be improved.

In addition, it is possible to make various design changes within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electric configuration of an electric power steering apparatus according to an embodiment of the present invention, together with a cross-sectional structure of a steering mechanism.

FIG. 2 is a flowchart illustrating a steering assist force control operation.

FIG. 3 is a graph showing an example of a relationship between a vehicle speed coefficient and a vehicle speed;

FIG. 4 is a flowchart illustrating a steering assist force control operation according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 steering mechanism 2 electric power steering device M motor 20 controller 22 vehicle speed sensor 23 torque sensor 25 direction indicator sensor

Claims (2)

[Claims] 1. An electric power steering device mounted on a vehicle having a direction indicator and generating a steering assisting force by using a rotating force of a motor, wherein a detecting means for detecting operation / non-operation of the direction indicator of the vehicle. And an electric power steering apparatus, comprising: a motor control means for controlling the motor to increase and correct the steering assist force when the detection means detects that the direction indicator is operating. A vehicle speed detecting means for detecting a vehicle speed; and a means for prohibiting an increase correction of the steering assist force when the vehicle speed detected by the vehicle speed detecting means exceeds a predetermined value. The electric power steering device according to claim 1.