JPS63180566A - Electric type power steering device - Google Patents

Abstract

PURPOSE:To make the assist increased in the steering withholding time than in the steering time, by furnishing a torque sensor on the delivery way of the steering operation, power, and controlling the output of a power unit responding to the torque detected by the torque sensor. CONSTITUTION:A torque sensor 56 is installed at a steering shaft 12, and arranged to detect the torque inflicted to the steering shaft 12 and to output the data on the detected torque to a microcomputer 54 through an A/D converter 58. The microcomputer 54 has a CPU 60 and a memory 64, and arranged to output a control signal responding to the torque detected by the torque sensor 56 to a servo amplifier 66 through a D/A converter 64. The servo amplifier 66 outputs a control signal depending on the signal from an assist sensor 68 to an electrometer driving control unity 50, and controls the current fed to an electromotor 28.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric power steering device used in vehicles such as automobiles, and more particularly to a steering torque sensitive electric power steering device.

BACKGROUND ART A power unit having a power source whose output can be controlled, such as an electric motor, is connected in a power transmission relationship in the middle of a steering operation force transmission path between a steering wheel and a steering gear device, and a power unit is connected in a power transmission relationship in the middle of a steering operation force transmission path between a steering wheel and a steering gear device, and a power unit is connected in a power transmission relationship in the middle of a steering operation force transmission path between a steering wheel and a steering gear device. An electric power steering device has already been proposed, which is configured to control the output of the power unit and generate a steering assist force in accordance with the torque. -163766.

Problems to be Solved by the Invention In hydraulic power steering devices, when the steering wheel is turned back, the hydraulic pressure generated increases due to friction around the hydraulic valve in the gearbox, and the steering wheel operation becomes light. A structural hysteresis characteristic occurs, but in the electric power steering device as described above, there is no particular hysteresis characteristic, so there is a problem that, for example, when holding the steering wheel while cornering, the steering wheel feels heavy.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved electric power steering device that eliminates the above-mentioned problems.

Means for Solving the Problems According to the present invention, a steering assist force is connected to the middle of a steering operation force transmission path between a steering wheel and a steering gear device, and a steering assist force is connected to the steering operation force transmission path between a steering wheel and a steering gear device. a torque sensor that detects the torque of the steering force transmission path; and a torque sensor that controls the output of the power unit according to the torque detected by the torque sensor so that the output of the power unit is lower when the steering is held than when steering. This is accomplished by an electric power steering system having a controller that increases the amount of power by a predetermined amount.

Effects and Effects of the Invention According to the above-described configuration, the steering assist force increases when the steering is held as compared to when steering, and good steering filling can be obtained even when the steering is held.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

In the figure, 10 indicates the steering wheel,
The steering wheel 10 is a steering shaft 12
, a universal joint 14, an intermezzo-eight shaft 16, and a universal joint 18. Further, the pinion shaft 22 is drivingly connected to a pinion shaft 32 of a steering gear device 30.

The steering gear device 30 is a rack and pinion type steering gear device, and includes a pinion 34 integrated with a pinion shaft 32 and a rack par 3 that meshes with the pinion 34.
6, and the rack par 36 is drivingly connected to a steering wheel 42 at both ends thereof via a tie rod end member 38 and a knuckle arm 40, respectively.

The reduction gear device 20 includes a driven gear 24 connected to a pinion shaft 22 as an output shaft, and a drive gear 26 that meshes with the driven gear 24. The drive gear 26 is fixedly connected to an output shaft 29 of an electric motor 28. has been done.

The electric motor 28 is connected to a power source 52 by a motor drive control device 50.
The rotational direction and rotational output are controlled by controlling the electric power supply by. Electric motor drive control device 50
is operated based on a control signal from a servo amplifier 66.

A torque sensor 56 is attached to the steering shaft 12, and the torque sensor 56 detects the torque acting on the steering shaft 12 and sends information regarding this to the microcomputer 5 via the A/D converter 58.
It is designed to output to 4.

The microcomputer 54 has a CPU 60 and a memory 62.
The control signal is sent to the servo amplifier 66 via the D/A converter 64 in accordance with the control characteristics shown in FIG. It is designed to be output.

The servo amplifier 66 takes in information regarding the assist force from the assist sensor 68 as feedback control information, and outputs a control signal to the motor drive control device 50 so that this assist force becomes equivalent to the control target motor output Tm.
The current applied to the electric motor 28 is controlled.

The assist sensor 68 may be a combination circuit of a shunt resistor and a signal amplification amplifier that detects the armature current of the motor 28, which is approximately proportional to its output torque.

Next, the operation of the electric power steering device according to the present invention will be explained with reference to the flowchart shown in FIG.

The routine of the flowchart shown in FIG. 2 is repeatedly executed at predetermined time intervals, and at the start, initialization is performed in step 10, and then the process proceeds to step 12.

In step 12, the steering torque Ts detected by the torque sensors 5 and 6 is read, and the steering direction, that is, the direction of rotation of the steering wheel 100 is detected from this steering torque Ts. After step 12, the process advances to step 14.

In step 14, the torque change rate ΔTs is calculated from the difference between the steering torque Ts read in step 12 and the steering torque Ts read in the previous step 12. After step 14, the process advances to step 16.

In step 16, it is determined whether the torque change rate ΔTs is equal to or greater than a predetermined value ΔT 5set close to a predetermined value O. When ΔTs > ΔT 5set, it is determined that steering is in progress and the process proceeds to step 18. On the other hand, when ΔTs>ΔT 8set is not satisfied, it is assumed that steering is being held and the process proceeds to step 20.

In step 18, the motor output Tl11 is determined according to the steering characteristics as shown in FIG. As shown in FIG. 3, the motor output Tl11 is determined to increase as the steering torque Ts increases. After step 18, the process proceeds to step 22.

In step 20, as shown in FIG. 3, the motor output Tm is determined according to the steering characteristics. As shown in FIG. 3, the motor output Tm at this time is determined to increase as the steering torque Ts increases, and the rate of increase is set to a larger value than during steering.

As a result, when the steering is held, the motor output Tff is lower than when steering.
l is determined to be a large value. After step 20, the process proceeds to step 22.

In step 22, step 18 or step 2
The signal of the motor output Tm determined in step 2 is sent to the servo amplifier 6.
6 is performed.

By performing control according to the flowchart as described above, a larger steering assist force is generated when the steering is held than when steering, which prevents the steering wheel from feeling heavy when the steering is held while cornering, and provides good steering even when the steering is held. You will be able to get better steering feel.

Although the present invention has been described in detail above with reference to specific embodiments, it is understood that the present invention is not limited thereto and that various embodiments are possible within the scope of the present invention. This will be obvious to businesses.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the electric power steering device according to the present invention, FIG. 2 is a flowchart explaining the operation of the electric power steering device according to the present invention, and FIG. 3 is a graph showing the control characteristics of the electric motor output with respect to the steering torque of the power steering device. DESCRIPTION OF SYMBOLS 10... Steering wheel, 12... Steering shaft, 14... Universal joint, 16... Intermezzo eight shaft, 18... Universal joint, 20...
- Reduction gear device, 22... Binion shaft, 24... Driven gear. 26... Drive gear, 28... Electric motor, 29... Output shaft. 30... Steering gear device, 32... Pinion shaft.

Claims (1)

[Claims] a power unit connected in the middle of a steering operation force transmission path between the steering wheel and the steering gear device and applying a steering assist force to the steering operation force transmission path; and a torque sensor that detects torque on the steering operation force transmission path; An electric power steering device comprising: a control device that controls the output of the power unit according to the torque detected by the torque sensor, and increases the output of the power unit by a predetermined amount when the steering is held compared to when the steering is being carried out.