JPH075082B2 - Electric power steering control device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electric power steering control device, and more particularly to a power steering control device that favorably returns a tire.

[Background of the Invention]

An electric power steering control device is disclosed, for example, in Japanese Patent Laid-Open No. 58-8.
It is known from publication 467.

FIG. 1 shows a conventional example of an electric power steering control device. The handle 1 is fixed to a handle shaft 2, and the handle shaft 2 is connected to a shaft 3A via a spring 11. The steering gear (hindre worm) 3 is connected to the shaft 3A, and the shaft 3A
Rotates according to the movement of. The sector roller 4 meshes with the steering gear 3 and receives the movement of the steering gear 3, and the rotational displacement of the sector roller 4 through the sector roller arm 4A, the drag link 4B, and the steering receiving arm 4c to the connecting portion 6D of the king pin and the king pin bearing. To convey.

The wheels 6 are configured to be driven independently. Wheel axle
6A means the original axle with independent suspension and is called the front axle or the rear axle depending on whether it is the front wheel or the rear wheel. The tie rod 5 has a role of making the driving directions of the left and right wheels 6 follow each other,
The driving directions of the left and right wheels are transmitted to each other via the wheel shaft arms 5A and 5B. The wheel shafts 6B and 6C are connected to the wheel 6 and transmit the movement of the sector roller 4 to the wheel 6.

The electric power steering mechanism includes a sensor 7, a controller 100, an electric motor 8, and gears 9 and 10. The sensor 7
The deviation between the handle shaft 2 and the shaft 3A of the steering gear 3 is detected. This deviation corresponds to the steering wheel operation amount.

The controller 100 takes in the detection deviation of the sensor 7 together with other necessary amounts, calculates the drive amount for driving the electric motor 8, and gives it to the electric motor 8. The electric motor 8 takes in the drive amount from the controller 100, and the small gear 9 mounted on the shaft.
To rotate. The large gear 10 is connected to the shaft 3A, receives the rotation amount of the small gear 9, and rotates the steering gear 3. This rotation is transmitted to the wheels 6 via the sector rollers 4 and the like to perform the necessary power steering operation.

A characteristic diagram of the sensor 7 is shown in FIG. Assuming that the steering wheel is in the neutral position and the output voltage at this time is V _n , the sensor output V becomes V> V _{n in} the rightward deviation, and the sensor output V becomes the leftward deviation. V <V _n . The overall characteristic is a linear characteristic. Therefore, _assuming that the output V is now at the deviation P position, the sensor 7 produces an output larger than the reference voltage V _n by ΔV.

The controller 100 takes in the output voltage of the sensor 7,
Calculate V. The controller 100 drives the electric motor 8,
The control is performed so as to eliminate the deviation P. This control is performed by the servo system. This reduces the driver's steering wheel operating force.

However, the restoring force of the tire may not work. The reason is that the rotational power of the electric motor 8 forms a transmission system that is transmitted to the steering gear 3 via the small gear 9 and the large gear 10. That is, the static torque of the electric motor 8 is substantially increased because it is via the gears 9 and 10 in addition to the original static torque. As a result, the static torque may be substantially larger than the restoring force of the tire 6 for returning in the straight traveling direction, and the tire 6 cannot be restored.

[Object of the Invention]

An object of the present invention is to provide a power steering control device capable of smoothly restoring a tire.

[Outline of Invention]

In the present invention, in the electric power steering control device that detects the deviation between the steering angle of the steering wheel and the tire angle and drives the tire angle with the electric motor so as to match the tire angle with the steering angle of the steering wheel based on the deviation, the magnitude of the deviation is increased. The steering direction is stored when the steering wheel is steered to a predetermined value or more. When the steering force for steering the steering wheel disappears, the direction of the static torque removing current flowing to the electric motor is stored in the storage means. It is determined according to the steering direction. As a result, even if you turn the handle in either direction,
If you let go of the handle, it will be possible to always pass a current in the direction that removes the static torque.

Example of Invention

FIG. 3 is a diagram for explaining the principle of the present invention, and FIG. 4 is a diagram for explaining its operation. If the steering wheel is to be turned to the right, the deviation displacement ΔE is + ΔE, and if the steering wheel is to be rotated to the left, the deviation displacement ΔE is −ΔE. Now, when the steering wheel is turned to the right, as shown in FIG. 4, the sensor output has a larger output voltage than that at the neutral position, the current for the stationary torque flows to the right, and the tire follows the steering wheel to the right. Move in the direction. Along with this, the restoring force increases. When the tire approaches the steering wheel position, the sensor output voltage decreases conversely and approaches the neutral position. When the driver releases his hand from the steering wheel during this process, the restoring force and the steering force of the balanced steering wheel are released, so the steering wheel on the spring 11 in Fig. 1 causes the steering wheel to move to the left of the tire. Direction, a deviation of −ΔE ₁ occurs.

The controller recognizes this deviation displacement-ΔE ₁ and outputs a command to flow a current corresponding to the stationary torque to the left. On the basis of this command, a current corresponding to the static torque to the left flows in the electric motor as an exciting current. The static torque to the left of the electric motor is removed by the flow of the current corresponding to the static torque to the left, only the restoring force of the tire works, and the tire goes straight.

The above is an example of removing the static torque to the left.
To remove the static torque in the right direction, a current having a polarity opposite to that in the left direction may be applied to the electric motor.

FIG. 5 shows an embodiment of an electric circuit for implementing the present invention. The controller 100 is composed of all parts except the sensor 7, the electric motor 8 and the battery 19. The controller 100 uses an analog method. Naturally, it is possible to realize it by a digital method.

The deviation detector 12 takes in the detection output of the sensor 7 and determines whether or not the amount of change is larger than the reference value ΔE _{0. If} it is larger than ΔE ₀ and is in the positive direction, the latch circuit 14 is latched. If the absolute value is larger than ΔE ₀ , it is in the negative direction and the latch circuit 16 is latched. The memory 13 stores a reference value ΔE ₀ , and this reference value ΔE ₀ serves as a reference value for determining whether it is necessary to newly supply a current for the stationary torque.

When there is a deviation amount in the positive direction, the transistor TR6 is turned on via the amplifier 15, and then the transistor TR3 → resistor R3.
→ A motor 8 → a resistor R2 → a transistor TR2 is formed, and a current determined by this path is passed through the motor 8 in the direction of the solid line arrow. By setting this current to a current for canceling the static torque, the static torque of the electric motor 8 can be removed.

At the time of the displacement of the deviation in the negative direction, the transistor TR5 is turned on via the amplifier 17, and then the transistor TR1 → the resistor R1.
→ A motor 8 → a resistor R8 → a transistor TR4 is formed as a path, and a current determined by this path is passed through the motor 8 in the direction of the dotted arrow. By setting this current as a current for canceling the static torque, the static torque of the electric motor can be removed.

Further, in FIG. 5, the main circuit 18 including the electric motor 8 comprises relay contacts L1, L2, L3, L4, a current detector CD and a transistor TR0. When rotating to the right, the contacts L3 and L2 are closed, and a current is passed in the direction of the solid arrow. When rotating counterclockwise, the contacts L1 and L3 are closed, and a current is passed in the direction of the dotted arrow. This main circuit operates when the output voltage of the sensor 7 has a large deviation from neutral, whether it is left rotation or right rotation. The diode D1 has a role of a freewheel diode. Naturally, this main circuit
When passing a current through 18, the transistor TR0 is kept conductive.

In short, the electric current for the original power steering flows through the electric motor 8 through the main circuit 18, and the electric current for removing the static torque flows when the static torque that prevents the restoring force is generated.

FIG. 6 shows the deviation detector 1 which forms the block diagram of FIG.
2, a concrete example of an actual electric circuit including the memory 13, the latch circuits 14 and 16, and the amplifiers 15 and 17 is shown. Memory 13
It consists of a potentiometer VR1 and this set value is the reference value ΔE.
Make ₀ . The sensor 7 is equivalently indicated by the variable resistor R0.
The deviation detector 13 includes resistors R5, R6, R7 and an operational amplifier OP1. The current input through the resistors R5 and R6 is deviated by the operational amplifier OP1, and the current in the positive direction or the negative direction is sent out through the resistor R8.

The latch circuits 14 and 16 are composed of diodes D2 and D3 and a capacitor CO. When the positive direction, the latch circuit 14 and 16 accumulates a positive output to the capacitor CO through the diode D2, and when the negative direction, the capacitor CO via the diode D3. Negative output is stored in.

The amplifier 15 includes resistors R9, R10, R11, R15 and an operational amplifier OP2, and the amplifier 17 includes resistors R12, R13, R14, R16 and an operational amplifier OP3. The outputs of the operational amplifiers OP2 and OP3 are the currents A and B required to flow the current for removing the static torque.

The difference between the variable resistor R0 and the potentiometer VR1 in FIG. 6 indicates the torque. For example, when the steering wheel is turned to the right, the voltage output from the operational amplifier OP1 is the capacitor CO
Stored in. That is, one of the outputs A and B is high when the steering wheel is turned to either side. If the handle is released when A = high, the outputs of the variable resistor R0 and the potentiometer VR1 become the same, and the output of the operational amplifier OP1 becomes zero. As a result, the electric charge stored in the capacitor CO is discharged through the diode D3, and the output B = high. As a result, a current that is in the opposite direction to the direction of the current flowing through the electric motor while the steering wheel is being turned and that removes the static torque flows through the electric motor.

〔The invention's effect〕

According to the present invention, the static torque of the electric motor can be relatively eliminated, and the phenomenon that the tire is not restored can be prevented. Also, since the steering wheel is always prioritized, the steering wheel is smooth and the feeling is good.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional power steering, FIG. 2 is a sensor characteristic diagram, FIG. 3 is a principle explanatory diagram of the present invention, FIG. 4 is an operational explanatory diagram of the present invention, and FIG. 5 is a control of the present invention. FIG. 6 shows an embodiment of the apparatus, and FIG. 7 ... Sensor, 12 ... Deviation detector, 8 ... Electric motor, 19 ...
… Battery, 18… Main circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Rokutan, Inventor Hideo Rokutan 2520, Takaba, Katsuta, Ibaraki, Sawa Plant, Hitachi, Ltd. Factory Sawa Factory (72) Inventor Kiyoshi Nemoto 2520 Takaba, Katsuta City, Ibaraki Prefecture Hitachi Factory Sawa Factory

Claims (1)

[Claims] 1. An electric power comprising a sensor for detecting a deviation between a steering angle of a steering wheel and a tire angle, and an electric motor for driving the tire angle so as to match the tire angle with the steering angle of the steering wheel based on the deviation detected by the sensor. In the steering control device, a storage means for storing a steering direction when steering is performed such that the deviation is equal to or larger than a predetermined value, and a static torque applied to the electric motor when the steering force for steering the steering wheel disappears. An electric power steering control device, comprising: a controller having means for determining a direction of the removing current according to a steering direction stored in the storage means and supplying the static torque removing current to the electric motor. .