JPH02155871A - Device for controlling steering force of motor-driven power steering - Google Patents

Abstract

PURPOSE:To improve steering stability by generating braking force by means of electromagnetic braking in a motor at the time of high speed traveling and controlling the braking force in accordance with a vehicle speed. CONSTITUTION:When vehicle speed is accelerated above a defined value, braking is judged by a motor changeover circuit 12 assisting/brake judging circuit 14 from the output signal of a vehicle speed sensor 10, thereby switching over relays 15, 16 to connect a motor 4 to a motor control circuit 13 side. In the circuit 13, the increase/decrease in the steering angle of a handle is judged by a steering angle increase/decrease judging circuit 20 and, at the time of judging an increasing condition, a relay ON/OFF circuit 21 is turned on, forming a closed circuit of the motor 4 and a slide rheostat 19. Thereby, the motor 4 is electromagnetically controlled generating braking force in the motor 4, which is loaded on a steering shaft via a clutch and a reduction gear. This braking force is increased in accordance with the vehicle speed. When the steering direction of the handle is in the direction of returning to neutral, no braking force is loaded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a steering force control device for electric power steering, and in particular, to appropriately control the steering force when a vehicle is running at high speed from the viewpoint of safety. .

As shown by chain line A in Figure 4, the steering force of conventional technology vehicles tends to be heavy when stationary or at low speeds, and light at high speeds.In particular, at high speeds, the steering force becomes too light than necessary, and the steering wheel This caused problems with steering safety.

To solve the above problem, in order to improve steering stability, a device equipped with electric power steering detects vehicle speed.
At low speeds, turn on the power steering switch,
While assist torque is added to manual torque to reduce steering force, at high speeds the power steering switch is turned off to prevent power steering from working, thereby eliminating the additional assist torque. Proposed.

Problem to be Solved by the Invention However, with the device described in ``2'', it is impossible to eliminate the addition of assist torque at high speeds and return to manual torque. The problem that the steering force becomes too light during high-speed running, as shown by the chain line in FIG. 4, resulting in a lack of steering stability has not been solved.

The present invention aims to solve the above-mentioned problems.The present invention includes a motor control circuit that generates a braking force by electromagnetic braking;
When driving at low speed when the vehicle speed is below a certain value, the motor is connected to the motor energization control circuit (1) to generate assist force to the motor, while when the vehicle speed is below a certain value (2), the motor is connected to the motor control circuit. and a motor switching circuit that switches the motor between assisting and braking so that the motor generates braking force, and is configured to load braking force on manual torque when driving at high speeds. The present invention provides a steering force control device.

Furthermore, the present invention disconnects the motor control circuit of the controller from the motor when the steering angle is in the direction of returning to the neutral position during high-speed driving, eliminates the load of braking force, and steers the controller away from the neutral position. The present invention provides a steering force control device characterized in that it is configured to apply a brake force only when the steering force is turned on.

By adopting the above-described configuration, it is possible to obtain steering stability in a manual steering system equipped with electric power steering by applying a braking force during high-speed running.

Means for Solving the Problems, that is, the present invention causes a motor used in an electric power steering device to generate a braking force by electromagnetic braking when driving at high speed, and controls the braking force according to the vehicle speed. The structure is such that a stable steering force is obtained by applying the braking force described in item 1 to the manual torque.

Specifically, the present invention includes a steering angle sensor that detects a steering angle of a steering wheel of an automobile, a torque sensor that detects a steering force, a vehicle speed sensor, a motor connected to a steering shaft, the steering angle sensor, the torque sensor, and the vehicle speed. It is equipped with a controller that controls the motor according to detection signals from the sensors, and the controller includes a motor energization control circuit that controls the energization of the motor according to the output signals from each sensor, and a motor control circuit that controls the energization of the motor according to the output signals from each sensor. Depending on the corner, when driving at low speeds where the steering force is heavy with only the mole torque, it is possible to improve operability by lightening the steering force by adding motor assist force, while with only manual torque, the steering force is light. When running at high speeds, where steering stability becomes a problem, steering stability can be improved by adding braking force to the manual torque to increase the steering force.

Further, even when the vehicle is running at high speed, the brake force load is removed when the steering wheel is returned to the neutral position, so the steering wheel does not return poorly.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples shown in the drawings.

In FIG. 1 showing the overall configuration of the steering force control device, l
is a steering wheel, 2 is a steering shaft fixed at one end of the steering wheel, 3 is a tire that is linked to the steering shaft 2 and steered according to the rotation of the steering wheel, and 4 is a steering torque that applies an 1-1-lux or brake torque to the steering torque of the manual steering wheel. The load motor is connected to a reduction gear 5 attached to the steering shaft 2 via a clutch 6.

7 is a controller that controls the motor 4. The steering shaft 2 is equipped with a steering angle sensor 8 that outputs a signal according to the steering angle of the steering wheel l, and a torque sensor 9 that outputs a signal according to the steering torque. The sensor IO is connected to the controller 7, and the controller 7 controls the switching of the motor 4 to assist or brake in accordance with the detection signals of the sensors 8, 9, and 10, and loads the steering shaft 2 with assist torque or brake torque. That's what I do.

As shown in FIG. 2, the controller 7 is provided with a motor current control circuit 11, a motor switching circuit 12, and a motor control circuit I3.
As shown in the figure, when the vehicle speed V reaches a certain value vl, the motor 4 is switched from assisting to braking, that is, v
When driving at low speeds below l, assist torque is added to manual torque.15.16 When it is determined that assist is being applied, the terminals 15b and 16b are closed to connect the motor 4 to motor current control circuit 11, while when it is determined that it is braking. At this time, the terminals 15a and 16a are closed and connected to the motor control circuit 13.

When the motor control circuit 13 is running at high speed when the vehicle speed is 1 or more,
The braking force generated by electromagnetic braking of the motor 4 is applied in accordance with the vehicle speed, and the braking force is controlled in accordance with the direction of rotation of the handle l (away from or returning from the neutral position). That is, the motor control circuit 13 includes a resistance control circuit 17 connected to the vehicle speed sensor lO, and a DC voltage operated by the resistance control circuit 17.
A servo motor 18, a rack 24 that meshes with a gear 23 attached to the output shaft of the servo motor 18, a slider resistor 19 connected to the rack 24 and the terminal 15a of the relay 15 of the motor switching circuit 12, and a steering angle connected to the steering angle sensor 8. Increase/Decrease Judgment Circuit 20, Steering Angle Increase/Decrease Judgment Circuit 20
, is connected to the terminal 16a of the relay 16 of the motor switching circuit 12, and when driving at a high speed of v1 or higher, brake torque is applied to the manual torque, so that the steering torque becomes as shown by the solid line B in Fig. 4. It is controlled as follows. and ■ When driving at a high speed of 1 or higher, when the handle 1 rotates in the direction returning to the neutral position, the brake torque load is eliminated, and only when the handle 1 rotates in the direction away from the neutral position, the brake torque is applied as described above. controlled to do so.

That is, the motor current control circuit 11 of the controller 7 is connected to the steering angle sensor 8, the torque sensor 9, and the vehicle speed sensor 10, and controls the current flowing to the motor 4 according to the output signals of these sensors.

The motor switching circuit 12 has the function of switching the motor 4 between assist use and brake use, and is connected to the vehicle speed sensor 10 and determines whether the motor 4 is used for assist or braking depending on whether the vehicle speed V reaches vl. /assist determination circuit 14, and relays 15, 16 that switch according to signals from the brake/assist determination circuit 14. A position sensor 25 of the DC servo motor I8 is provided to determine the position of the relay 0N10FF circuit 21 and the slider resistor 19.

The operation of this device will be explained below based on the flowchart shown in FIG.

Relay 15 of motor switching circuit 12 at the time of initial setting.
16 has a 1nle (15a, 16a) closed,
During low-speed driving after the start of driving, the motor switching circuit The unstuck/brake determination circuit 14 of No. 12 determines that the brake is assist, and switches the relays 15 and 16 to the b side (15b,
16b). Therefore, motor 4 is relay 1
A closed circuit is formed with the motor current control circuit 11 via the motor 5.16, and the motor 4 is driven to rotate according to the amount of current supplied from the motor current control circuit 11. The clutch 6 is turned on in response to a signal from the motor current control circuit.
The speed reducer 5 is rotated through the steering shaft 2 to apply assist torque to the steering shaft 2. At this time, the motor current control circuit II controls the current flowing through the motor 4 based on the detection signals inputted from the steering angle sensor 8, torque sensor 9, and vehicle speed sensor 10, and therefore controls the steering direction, manual torque, and An appropriate torque corresponding to the vehicle speed is output from the motor 4 and added to the manual torque.

On the other hand, the vehicle speed is accelerated and becomes more than v1, (vehicle speed y>v
l, ) becomes Yes, the unstuck/brake determination circuit I4 of the motor switching circuit 11 determines that the brake is applied based on the output signal from the vehicle speed sensor 9.

Depending on the output signal, relays I5 and I6 are 15a.

16a side, the motor 4 is switched to the motor control circuit I3
connected to the side. That is, the armature of the motor 4 is connected to the relay 15.
is connected to the end of the slider resistor 19 via the relay ON10 FF circuit 2 via the relay 16.
Connected to I. On the other hand, in the motor control circuit I3,
An increase or decrease in the steering angle of the steering wheel 1 is determined by the steering angle increase/decrease determination circuit 20, and when it is determined that the steering angle is in an increasing state (a state in which the steering wheel 1 is rotated away from the neutral position), that is, after T seconds, the steering angle 2
4, and the resistance value of the slider resistor 19 is changed by changing the position of the rack 24.

On the other hand, if the steering direction of the handle I is to return to the neutral position, the application of braking force will worsen the return, so no braking force is applied. That is, when the steering angle decreases and θ2-01>0 is No, the steering angle increase/decrease determination circuit 2
The relay 0N10FF circuit 21 is turned off by the 0 output signal.
F, the connection between the motor 4 and the slider resistor 19 is cut off, so that no braking force is generated in the motor 4.

As described above, according to the present control device, when the vehicle speed V is running at a low speed of v1 or less, as shown by the solid line B in FIG. Steering force is reduced compared to On the other hand, when the vehicle is running at a high speed with a vehicle speed of 71 or higher and the steering direction of the steering wheel 1 is in a direction away from the neutral position, the motor 4 outputs a braking force according to the vehicle speed to change the manual torque angle to 02, If the steering angle after (T-△T) is θI, if θ2-191>0 is Yes, the connected relay
ON10 FF The F circuit 21 is turned on. The relay is ON
Since the 10FF circuit 21 is connected to the other end of the slider resistor 19, a closed circuit is formed between the motor 4 and the slider resistor 19. Therefore, the motor 4 is electromagnetically braked, a braking force is generated in the motor 4, and the braking force is applied to the steering shaft 2 via the clutch 6 and the speed reducer 5. This braking force is controlled by changing the resistance value of the slider resistor 19 according to the vehicle speed V, and the braking force is increased as the vehicle speed V increases, as shown by the shaded area C in FIG. That is, the position of the slide duck is determined based on a signal from the position sensor 25 of the DC servo motor 18, and when the vehicle speed V changes, the rack 24 is driven by the DC servo motor I8 so that the position of the slide duck changes accordingly. The gear 23 is rotated by the drive of the DC zarpo motor I8, and the engaged rack 24 moves, and a load is applied to the rack according to the position of the DC zarpo motor 18, so the steering force becomes heavier than the chain line A below the manual torque. This improves steering stability when driving at high speeds.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and for controlling the braking force of the motor, appropriate known methods such as a method of switching the resistance in stages, a method of changing the duty ratio of a chopper circuit, etc. may be adopted. I can do it.

Effects of the Invention As is clear from the above explanation, according to the steering force control device for electric power steering according to the present invention, the motor is switched between an unstuck operation and a brake operation according to the vehicle speed, and when driving at high speed, Since the motor generates braking force and the braking force is applied to the steering shaft to increase the steering force, it is possible to improve steering stability during high-speed driving. Also, when driving at high speeds, if the steering wheel is rotated in the direction to return it to the neutral position,
Since the load of the braking force mentioned above is eliminated, there is no problem with the return of the brake.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of a steering force control device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the controller 7, FIG. 3 is a flowchart showing the operation of the device, and FIG. FIG. 2 is a diagram comparing the steering force of the present device with that of a conventional example. ■...Handle, 2...Steering shaft, 3...Tires, 4...Motor, 5...Reducer,
6...Clutch, 7...Controller, 8...
Steering angle sensor, 9...torque sensor, IO...vehicle speed sensor, 11...motor current control circuit, 12...motor switching circuit, 13...motor control circuit, 14...assist/brake determination circuit, 15.16・・・
Relay 17...Resistance control circuit, 18...DC servo motor, 19...Slidac resistance, 20, 2 l, 24, 25, - Steering angle increase/decrease judgment circuit, - Relay ON10 FF circuit.・Rack, ・Position sensor. Patent applicant: Haka Asmo Co., Ltd. (1 person) Representative: Haka Yamabo, patent attorney (2 persons)

Claims (1)

[Claims] 1. A steering angle sensor that detects the steering angle of a steering wheel of an automobile, a torque sensor that detects steering force, and a vehicle speed sensor;
The controller includes a motor connected to the steering shaft and a controller that controls the motor according to detection signals from the steering angle sensor, torque sensor, and vehicle speed sensor. A motor energization control circuit that controls the energization of the motor, a motor control circuit that generates braking force by electromagnetic braking of the motor according to the vehicle speed and steering angle, and a motor energization control circuit that controls the energization of the motor when the vehicle speed is below a certain value and is running at low speed. The motor is connected to the control circuit side and generates assist force to the motor.When the vehicle speed is above a certain value, the motor is connected to the motor control circuit and the motor is divided into assist and brake forces so that the motor generates braking force. What is claimed is: 1. A steering force control device for electric power steering, comprising: a motor switching circuit that switches to a motor switching circuit, and is configured to load brake force on manual torque during high-speed driving. 2. The motor control circuit of the controller is configured to disconnect from the motor when the steering angle is in the direction of returning to the neutral position during high-speed running, thereby eliminating the brake force load. Device.