JP2776776B2 - Electric power steering device - Google Patents

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 reducing the steering force of a driver by applying the power of an electric motor to a steering system as a steering assist force. TECHNICAL FIELD The present invention relates to an electric power steering apparatus that improves steering feeling deterioration due to steering assist force decrease correction by detecting a collision state.

[0002]

2. Description of the Related Art A conventional electric power steering apparatus is
As disclosed by the present applicant in Japanese Patent Application Laid-Open No. 62-168759, the motor drive amount corresponding to the steering torque is gradually increased with time when the control device is started, such as when the ignition key is turned on. The auxiliary steering force of the electric motor acting on the steering system is gradually increased so as to match the target value.

[0003] With this, even when the driver turns off the steering wheel and turns on the ignition switch to start the electric power steering device, a large steering assist force corresponding to the stationary steering torque is suddenly applied to the steering system. , And the steering assist force gradually increases (hereinafter, referred to as "soft start control"), so that the steering feeling at the time of startup is kept good.

Further, the applicant of the present invention has disclosed Japanese Patent Application Laid-Open No. 64-9064.
As disclosed in Japanese Patent Application Laid-Open Publication No. H11-163, a conventional electric power steering apparatus includes a steering force detecting means for detecting a steering force (steering torque) of a steering system, or a steering force detecting means and a steering speed (steering rotation speed) of the steering system. A steering speed detecting means for detecting, and an overload preventing means, wherein the overload preventing means is provided when the steering force exceeds a predetermined value, or when the steering force exceeds a predetermined value and the steering speed is equal to or less than a predetermined value. It is configured to reduce the current of an electric motor that operates to apply a steering assist force to a steering system.

Thus, for example, in the case of the rack and pinion type, when a steering force is further applied despite the fact that the rack shaft has reached the maximum steering position (abutting the rack end) by the driver's steering operation, Or, when the steering force exceeds a predetermined value, or when the steering force is applied even though the steered wheels cannot be steered due to obstacles on the road, A state in which the steering speed exceeds the predetermined value and the steering speed is equal to or lower than the predetermined value (hereinafter referred to as “steering end state”) is detected, and unnecessary current flowing through the motor is reduced to reduce power consumption of the motor. In addition, deterioration and breakage of the motor and the switching elements (for example, power FET: field effect transistor) of the bridge circuit that drives the motor due to heat generation and the like are prevented.

[0006]

SUMMARY OF THE INVENTION In an electric power steering apparatus provided with both soft start control and control for reducing motor current by detecting a steering contact state (hereinafter referred to as "unload control"), a driver operates a steering wheel. When the vehicle starts to be started (the ignition switch is turned on) while operating, soft start control is applied, and the steering rotational speed or the motor rotational speed is sufficiently low (steering thrust) despite the steering torque being sufficiently large. In the unload control state, the motor current (steering assist force) is unnecessarily reduced and corrected, resulting in a steering characteristic contrary to the driver's intention, which causes a problem that the steering feeling is deteriorated.

There is a similar problem in an electric power steering apparatus which has a soft start control and is configured to detect an abutting state of a steering when a steering torque exceeds a predetermined value and to perform an unload control.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. The purpose of the present invention is to inhibit the unload control in the soft start control and to provide a stable steering feeling both at the time of starting and in the state where the steering is pressed. An object of the present invention is to provide an electric power steering device that can obtain the above.

[0009]

According to a first aspect of the present invention, there is provided an electric power steering apparatus comprising: a control unit for prohibiting an operation of a correction unit while a soft start control unit is operating; It is characterized by comprising a correction stopping means for limiting.

In the electric power steering apparatus according to the present invention, the control means includes correction stop means for inhibiting or restricting the operation of the correction means while the soft start control means is operating. Unload control can be prohibited even if a contact state is detected.

According to a second aspect of the present invention, the unload control is performed based on the steering torque and the steering rotational speed or the electric motor rotational speed. Can be detected more accurately.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The electric power steering apparatus according to the present invention includes a soft start control that smoothly raises a steering assist force acting on a steering system at an initial operation immediately after the control unit starts control, and a state in which a steering contact state is detected. An unload control that reduces and corrects the steering assist force acting on the steering system, and prohibits or restricts the unload control during the soft start control at the time of the initial operation and controls the steering fee associated with the unload control at the time of the initial operation The purpose of the present invention is to improve the lowering of the ring and obtain a stable steering feeling.

FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention. In FIG. 1, an electric power steering apparatus 1 includes a universal joint 3 on a steering shaft 2 provided integrally with a steering wheel 17.
A manual steering force generating means 6 is connected to a pinion 5A of a rack & pinion mechanism 5 provided in a steering gear box 4 via a connecting shaft 3 provided with A and 3B.

The rack shaft 7 is provided with rack teeth 7A meshing with the pinion 5A, and reciprocates by the meshing of the rack teeth 7A.
The left and right front wheels 9 as steering wheels are connected to both ends thereof via tie rods 8.

In this way, the steering wheel 1
At the time of steering, the front wheels 9 are steered by manual steering via a normal rack and pinion type manual steering force generating means 6 to change the direction of the vehicle.

In order to reduce the steering force by the manual steering force generating means 6, an electric motor 10 for supplying a steering assist force is disposed coaxially with the rack shaft 7, and a ball screw mechanism 11 provided coaxially with the rack shaft 7. Is converted to thrust through the rack shaft 7
(Ball screw shaft 11A).

A steering torque sensor 12 for detecting the direction and magnitude of a driver's manual steering torque is disposed in the steering gear box 4, and a steering torque of an analog electric signal corresponding to the steering torque detected by the steering torque sensor 12 is provided. The signal T _S is provided to the control means 15. Alternatively, a steering torque sensor 12 for detecting the direction and magnitude of the driver's manual steering torque, and a steering rotational speed sensor 13 for detecting the direction and magnitude of the steering rotational speed of the steering wheel 17 operated by the driver are arranged. steering torque signal T _S of the analog electric signal sensor 12 corresponding to the steering torque detected, controls each of the steering rotational speed signal N _S of the analog electric signal steering rotational speed sensor 13 corresponding to the steering rotational speed detected means 15 To provide.

[0018] Incidentally, the motor rotation speed sensor for detecting a rotational speed of the electric motor 10 instead of the steering speed sensor 13 is provided, it is also possible to calculate the steering speed N _S of several 1.

[0019]

N _S = K ₁ (N _M −dT _S / dt) where K ₁ is a constant, N _M is the motor rotation speed, dT _S / d
t is a differential value of the steering torque T _S

Further, a motor rotation speed sensor is arranged in place of the steering rotational speed sensor 13, feed steering rotational speed N _S motor rotation speed signal is the motor rotational speed sensor detected instead of the (N _M) to the control unit 15 May be configured.

Further, a motor voltage sensor and a motor current sensor are provided in place of the motor rotation speed sensor, and the motor voltage V _M detected by the motor voltage sensor and the motor current I _M detected by the motor current sensor are used to calculate the motor speed from the equation (2). The rotation speed N _M can also be calculated.

[0022]

N _M = (V _M -K ₂ * I _M ) / K ₃ where K ₂ and K ₃ are constants

The control means 15 is composed of various arithmetic means, processing means, signal generation means, memory and the like based on a microprocessor, and a motor control signal V _O (for example, an ON signal and a PWM signal) corresponding to the steering torque signal T _S. To control the driving of the motor driving means 16.

The control means 15 controls the steering torque signal T
_S or steering torque signal T _S and a correction means for reducing the correction steering speed signal N _S or motor rotation speed (N _M) target current signal corresponding to the steering torque signal T _S based on (I _MS), The steering torque signal T _S exceeds a predetermined value, or the steering torque signal T _S exceeds a predetermined value, and the steering rotation speed signal N _S or the motor rotation speed (N _M ) falls below a predetermined value (steering end). When the (state) condition is detected, the unload control for limiting the drive of the electric motor 10 by performing the decrease correction of the target current signal ( _IMS ) is performed.

Further, the control means 15 has a soft start control means, and when the ignition switch 18 is turned on and a large steering torque is applied at the initial operation when the control means 15 starts the control, the control means 15 controls the steering torque. the corresponding target current signal not rapidly raised to (I _MS), soft-start control motor 10 gradually increases to the target current signal (I _MS) is increased gradually steering assist power acting.

Further, the control means 15 includes a correction stopping means, which prohibits or restricts the unload control during the soft start control and prohibits the reduction correction of the target current ( _IMS ) during the soft start control by the unload control. Control to execute the original soft start control.

The motor driving means 16 is composed of, for example, a bridge circuit composed of switching elements of four power FETs (field effect transistors), and the motor control signal supplied from the control means 15 in response to the steering torque signal T _S. V
Outputs a motor voltage V _M to drive the motor 10 based on the _O (mixed signal of the PWM signal and an ON signal).

The ignition switch 18 is connected to a battery 19
Is connected to, together with the start of the vehicle and turned on, it supplies the ignition information I _G (eg, H-level) to the control unit 15 indicating the ON operation. Further, the ignition switch 18 generates a driving power supply (for example, 5 V system) for a control system via a constant voltage circuit (not shown),
To the operating state.

FIG. 2 is a block diagram of a main part of the electric power steering apparatus according to the first embodiment. In FIG.
The control means 15 of the electric power steering device 1 includes a target current signal setting means 21, a soft start control means 22,
A drive control unit 23, a correction unit 24, and a correction stop unit 28 are provided.

The target current signal setting means 21 is constituted by A / D conversion means and a memory such as a ROM.
The steering torque signal T _S fed into a steering torque signal T _D digital from, into a target current signal I _MS which is set in advance based on the steering torque signal T _D, to the steering torque signal T _D supplying a target current signal I _MS to the multiplication means 27 of the correction means 24.

FIG. 10 shows a characteristic diagram of the steering torque signal (T _D ) -target current signal ( _IMS ). As shown in FIG. 10, the target current signal setting means 21 supplies a positive polarity target current signal _IMS (+) to the steering torque signal T _D (+ polarity) corresponding to the steering torque in the right direction. whereas, leftward steering the steering torque signal corresponding to the torque T _D supplies (- - polarity) is for the negative polarity target current signal I _MS ().

The soft-start control 22 timer means, a rising-setting means and the like, the target to be supplied with target current signal I _MF on the basis of the ignition information I _G supplied from the ignition switch 18 from the target current setting unit 21 from the 0 It increased gradually over time until the current I _MS, a target current signal I _MS which increases rapidly at the start of the vehicle increases gradually provided to multiplier 27 as the target current signal I _MF.

FIG. 3 is a block diagram showing one embodiment of the soft start control means. In FIG. 3, the soft start control means 22 includes a timer means 31, a rising setting means 3
2. It has a switching means 33. The timer means 31 is constituted by, for example, a mono-multi vibrator, and switches the timer signal τ _K (for example, an H level pulse signal) for a predetermined time τ _K to the rise setting means 32 by using the ignition information _IG (H level) as a trigger. To the means 33.

The rise setting means 32 is constituted by function operation means, the timer signal tau _K and the target current setting unit 21 which is supplied from the timer means 31 based on the target current signal I _MS supplied primary function (I _MS * t / τ _K), or an exponential function (1-e ^- τt) * calculates the I _MS, supplied to the switching means 33 the target current signal I _MO that increases with increasing time t.

The switching means 33 has a switching function of software control, perform the switching of the target current signal I _MS and the target current signal I _MO based on the timer signal tau _K supplied from the timer means 31, the selected target current The signal is output to the multiplication means 27 as a target current signal _IMF .

For example, when the timer signal τ _K is at the L level, the target current signal _IMS is selected. When the timer signal τ _K is at the H level for a predetermined time τ _K , the target current signal I _{MO is selected.}
Select

FIG. 4 is a waveform diagram of each part of the soft start control means. (A) the waveform of the ignition information I _G in FIG,
(B) shows the waveform of the timer signal τ _K , and (c) shows the waveform of the target current signal I _MO from the rise setting means.
(C) In FIG.
_MO indicates a characteristic calculated by a linear function, and a curve (indicated by a dashed line) indicates a characteristic obtained by calculating the target current signal _IMO by an exponential function.

As described above, the soft start control means 22
Because with a, at the time of a vehicle ignition switch is turned on starting can be increased gradually from zero with the passage of the rise of the target current signal I _MS time.

The correction means 24 includes a correction condition determination means 25,
Correction coefficient generation means 26, comprising a multiplication unit 27, the correction coefficient K _H a (0 <K _H ≦ 1) generated based on the steering torque signal T _S supplied from the steering torque sensor 12, the correction coefficient K _H The target current signal _IMF is multiplied by the target current signal _IMF.
Is reduced and the target current signal _IMSH is
To supply.

The correction condition judging means 25 includes a memory such as a ROM and a comparing means, and compares the steering torque signal T _S supplied from the steering torque sensor 12 with a reference torque value _TF set in a memory in advance. When the torque signal T _S exceeds the reference torque value _TF (T _S > T _R ), the correction judgment signal J
_H (for example, H level) is provided to the correction coefficient generating means 26. The reference torque value T _F is set to a value corresponding to a sufficiently large steering torque signal T _S , such as in the state where the steering is pressed.

The correction coefficient generator 26, for example, when the correction determination signal J _H of the H level is supplied predetermined correction factor _{K H (0 <K H <} 1), the correction determination signal J _H L level When supplied, the correction coefficient K _H (= 1) which gradually increases to 1 in a predetermined time is supplied to the multiplication means 27.

FIG. 5 is a block diagram showing an embodiment of the correction coefficient generating means. In FIG. 5, the correction coefficient generating means 2
6 includes a correction coefficient setting means 35 and a time gradual increase / decrease means 36. The correction coefficient setting means 35 is provided with a memory such as a ROM, and stores in advance 1 and a coefficient of K _C which is less than 1, and corrects the correction coefficient 1 based on the L level correction determination signal J _H , while determining the correction level of H level. and outputs the correction coefficient K _X of the two values of the correction coefficient K _C below 1 based on the signal J _H in the time increasing down means 36.

The time gradual increase / decrease means 36 has two types of function calculation means and timer means, respectively. When the correction judgment signal J _H switches from L level to H level, the correction judgment signal J _H becomes L level. By calculating and outputting a predetermined function (for example, a linear function) from the correction coefficient 1 to the correction coefficient K _C at which the correction determination signal J _H is at the H level, the fall time T _{A is obtained.}
Continuously decreases in the correction coefficient falling until time T _A after the predetermined time T _K constant value _{K C (0 <K C <} 1) a correction coefficient K _H
Is supplied to the multiplication means 27.

On the other hand, when the correction judgment signal J _H changes from H level to L
When switched to the level, the correction coefficient K _C from the up correction coefficient 1 another predetermined function (e.g., a linear function) by calculating and outputting a continuously increased at the rising time T _B, time (T _K + T _B) after the correction the correction coefficient 1 factor K _H
Is supplied to the multiplication means 27.

FIG. 6 shows an example of a time characteristic diagram of the correction coefficient. In FIG. 6, when the correction determination signal J _H switches from the L level to the H level, the correction coefficient K _H becomes
From time t = 0 to time t = T _A 1 linear function (K _H = -α
* T + 1), the decrease correction is performed, and the time t = T _A
The correction coefficient K _C (constant value) is maintained until a predetermined time T _K thereafter.

On the other hand, when the correction judgment signal _JH switches from the H level to the L level at the predetermined time T _K , the correction coefficient K _C becomes a one-hour function (K) from the time T _K to the time (T _K + T _B ). _H = K _C + β * t), the recovery correction is increased to the correction coefficient 1, and the correction coefficient 1 is maintained after the time (T _K + T _B ). Note that the rising slope β is set to be larger than the falling slope α.

The multiplying means 27 has a multiplier or a software-controlled multiplying function, and multiplies the correction coefficient K _H supplied from the correction coefficient generating means 26 with the target current signal I _MF supplied from the soft start control means 22. (K _H * I _MF ) is executed, and the target current signal I _MSH (= K _H * I _MF ) obtained by reducing the target current signal I _MF by the correction coefficient K _H is used as the drive control means 23
To provide.

The correction stop means 28 timer means, a buffer means and the like, the correction stop signal for a predetermined time tau _S ignition information I _G H level as a trigger S _T (eg, L
Level, and the correction determination signal J _H is forcibly held at the L level for a predetermined time τ _S.

FIG. 7 is a block diagram showing an embodiment of the correction stopping means. 7, the correction stopping means 28 includes a timer means 38 and a buffer means 39. Timer means 3
Numeral 8 is constituted by, for example, a mono-multi vibrator, and supplies a timer signal τ _S (for example, an L level pulse signal) for a predetermined time τ _{S to} the buffer means 39 by using the ignition information _IG (H level) as a trigger.

[0050] Buffers means 39, for example constituted by an open drain output Buffers, to the output of the correction condition determining means 25 the same signal as the timer signal tau _S (L-level pulse signal) as a correction stop signal S _T.

FIG. 8 is a waveform diagram of each part of the correction stopping means.
(A) the waveform of the ignition information I _G in the figure, respectively the waveform of the timer signal tau _S and the correction stop signal S _T in (b) FIG.

[0052] correction stop signal S _T will preserve from the ignition switch 18 is turned on to forcibly L level correction determination signal J _H predetermined time tau _S, the predetermined time tau _S correction decision signal J _H State (H level or L level)
Irrespective of the level), the correction coefficient K _H output from the correction coefficient generating means 26 is set to 1, and the target current signal I _MF is set to the target current signal I _MSH (= I _MF ) without _{performing the} decrease correction. Can be. The predetermined time τ _S is set to be the same as the time τ _K of the timer signal τ _K output from the timer means 31 of the soft start control means 22.

The drive control means 23 comprises a PI controller or a PID controller, and a PWM (pulse width modulation) signal generation means. The target current signal _IMSH supplied from the multiplication means 27 is controlled by PI (proportional / integral) or PID
After performing (proportional / integral / differential) control, the target current signal I
_An electric motor control signal V _O composed of a hybrid signal of the PWM signal V _PWM and the ON signal V _ON corresponding to the _MSH is supplied to the electric motor driving means 16.

As described above, in the electric power steering apparatus 1 according to the first aspect, the control means 15 is provided with the correction stop means 28 for inhibiting the operation of the correction means 24 while the soft start control means 22 is operating. During the predetermined time τ _S during which the ignition switch 18 is turned on and the soft start control is being performed, the unload control can be prohibited even if the steering contact state is detected.

FIG. 9 is a block diagram of a main part of the electric power steering apparatus according to the second aspect. In FIG.
The electric power steering device 1 includes a steering rotation speed sensor 1
3 or the motor rotation speed sensor 14 is provided,
The control means 40 is provided, and the correction condition determination means 42 of the correction means 41 is controlled by the steering torque signal T _S and the steering rotation speed signal N _S
Or point adapted to generate a correction determination signal J _H based on the motor rotation speed signal N _M is different from FIG.

The correction means 41 includes a correction condition determination means 42,
A correction coefficient generation unit 26 and a multiplication unit 27 are provided. The correction condition judging means 42 comprises a plurality of memories and a plurality of comparing means, and the steering torque signal T _S supplied from the steering torque sensor 12, the steering rotation speed signal N _S supplied from the steering rotation speed sensor 13, or the motor rotation. based on motor rotation speed signal N _M supplied from the speed sensor 14, a steering torque signal T _S exceeds the reference torque value _{T F (T S> T F} ), and the steering speed signal N _S is the reference steering speed value N _F or less (N _S
≦ N when _F) or the motor rotation speed signal N _M is less than the reference motor speed value N _MF of (N _M ≦ N _{M F)} is, for example, H
The level correction determination signal _JH is supplied to the correction coefficient generating means 26.

The correction coefficient generating means 26 has the same configuration and operation as in FIG. 5, stores 1 and a coefficient of K _C which is less than 1 in advance, and sets the correction coefficient 1 based on the L level correction judgment signal J _H. On the other hand, a binary correction coefficient K _H of a correction coefficient K _C which is less than 1 is output to the multiplication means 27 based on the H level correction determination signal J _H , and is output from the soft start control means 22 with this correction coefficient K _H. The target current signal I _MF is controlled to be the target current signal I _MSH (= K _H * I _MF ).

As shown in FIG. 7, the correction stopping means 28 outputs a correction stop signal _ST (L level) based on the ignition information _IG (H level), and inhibits the H level correction judgment signal _JH . As a result, the reduction correction (unload control) of the target current signal at the time of starting the vehicle is prohibited.

[0059] Thus, the electric power steering apparatus 1 according to the second aspect, the control means 40, the steering torque signal T _S, and the steering rotational speed signal N _S or steering thrust based on the motor rotation speed signal N _M Since the correction means 41 is provided for generating a correction coefficient K _H for determining the application state and reducing the target current signal I _MF based on the correction determination signal J _H , it is possible to more accurately detect the steering contact state. Can be.

Further, similarly to the first aspect, the correction stopping means 2
Since with 8, decrease correction of the target current signal I _MF during soft-start control when the vehicle started (unload control) can be prohibited.

As described above, in the embodiment, immediately after the ignition key is turned on as the initial operation of the control means, other modes are conceivable. For example, when the failure is removed from a state in which the electric power steering apparatus does not perform the steering assist (manual steering) due to a minor failure, and the steering assist is started.

Although the embodiment has been described with reference to an example in which the unload control is completely prohibited during the soft start control, it is possible to limit the unload control. For example, in FIG. 2, the L-level correction stop signal ST from the correction stop means 28 is _output.
Is output, the reference torque value T _FH compared by the correction condition determination means 25 is changed to the reference torque value T _F during normal control.
By setting it to be larger than (T _FH > T _F ), it is possible to substantially prevent the unload control from being entered.

[0063]

As described above, in the electric power steering apparatus according to the first and second aspects, the correction stopping means for inhibiting or restricting the operation of the correction means while the soft start control means is operating. During soft start control at the start of the vehicle, unload control can be prohibited or limited even if the steering contact state is detected, so that stable steering can be performed both at the start and in the steering contact state. Feeling can be obtained.

Since the correcting means according to the second aspect can detect the state of the steering contact more accurately,
A more optimal steering feeling can be obtained.

Therefore, it is possible to provide an electric power steering apparatus with stable soft start control and unload control.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electric power steering device according to the present invention.

FIG. 2 is a block diagram of a main part of the electric power steering apparatus according to claim 1;

FIG. 3 is a block diagram of an embodiment of a soft start control unit.

FIG. 4 is a waveform diagram of each part of the soft start control means.

FIG. 5 is a block diagram of an embodiment of a correction coefficient generation unit.

FIG. 6 is an example of a time characteristic diagram of a correction coefficient;

FIG. 7 is a block diagram of an embodiment of a correction stopping unit.

FIG. 8 is a waveform diagram of each part of the correction stopping means.

FIG. 9 is a block diagram of a main part of the electric power steering apparatus according to claim 2;

FIG. 10: Steering torque signal (T _D ) -target current signal (I
_MS ) Characteristic diagram

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering shaft, 3 ... Connecting shaft, 3A, 3B ... Universal joint, 4 ... Steering gear box, 5 ... Rack & pinion mechanism, 5
A: Pinion, 6: Manual steering force generating means, 7: Rack shaft, 7A: Rack teeth, 8: Tie rod, 9: Front wheel, 10
... electric motor, 11 ... ball screw mechanism, 11A ... ball screw shaft, 12 ... steering torque sensor, 13 ... steering rotational speed sensor, 14 ... electric motor rotational speed sensor, 15, 40 ... control means, 16 ... electric motor drive means, 17 ... Steering wheel, 18: ignition switch, 21: target current signal setting means, 22: soft start control means, 23: drive control means, 24, 41: correction means, 25, 42: correction condition determination means, 26: correction coefficient generation Means 27 multiplying means 28 correction stopping means 31 and 38 timer means 3
2 ... rising setting means, 33 ... switching means, 35 ... correction coefficient setting means, 36 ... time gradually increasing and decreasing means, 39 ... buffer means,
I _G ... ignition _{information, I MF, I MO, I} MS, I MSH ...
Target current signal, J _H ... correction decision _{signal, K C, K H, K} X ... correction coefficient, N _F ... reference steering speed value, N _M ... motor rotation speed signal, N _MF ... reference motor speed value, N _S : steering rotation speed signal, T _A : fall time, T _B : rise time, τ _K ,
τ _S, T _K ... predetermined time, S _T ... correction stop signal, T _F ... reference torque value, T _S ... steering torque signal, V _M ... motor voltage, V _O
... Motor control signal.

Continuation of front page (56) References JP-A-7-156817 (JP, A) JP-A-7-137651 (JP, A) JP-A-6-8839 (JP, A) JP-A-4-299085 (JP, A) JP-A-60-229866 (JP, A) JP-A-62-231870 (JP, A) JP-A-62-168759 (JP, A) JP-A-64-9064 (JP, A) 7-186994 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B62D 5/04 B62D 6/00

Claims (2)

(57) [Claims] An electric motor for applying an auxiliary steering force to a steering system; a steering torque sensor for detecting a steering torque of the steering system; and a target current signal corresponding to at least the steering torque detected by the steering torque sensor. Control means for controlling the drive of the electric motor, and at the time of initial operation immediately after the control means starts control, a soft start control means for gradually increasing the target current signal with time to a value corresponding to the steering torque, Correction means for reducing and correcting the target current signal at least when the steering torque exceeds a predetermined value. The electric power steering apparatus, wherein the control means is configured to control the correction means while the soft start control means is operating. An electric power steering device comprising a correction stopping means for prohibiting or restricting an operation. Packaging equipment. 2. An electric motor for applying an auxiliary steering force to a steering system, a steering torque sensor for detecting a steering torque of the steering system, a steering rotational speed sensor for detecting a steering rotational speed of the steering system, or an electric motor for the electric motor. A motor rotation speed sensor that detects a rotation speed; and a control unit that generates a target current signal corresponding to at least a steering torque detected by the steering torque sensor to control driving of the motor, and the control unit controls the motor. Soft start control means for gradually increasing the target current signal to a value corresponding to the steering torque at the time of the initial operation immediately after the start, and the steering torque exceeds a predetermined value and the steering rotation speed or the motor rotation speed is equal to or less than the predetermined value. In this case, the electric power steering includes a correction means for reducing and correcting the target current signal. The electric power steering apparatus according to claim 1, wherein the control unit includes a correction stop unit that prohibits or restricts the operation of the correction unit while the soft start control unit is operating.