CN202038360U - Electric power-assisted steering transmission mechanism and electric power-assisted steering mechanism - Google Patents

Abstract

The utility model relates to an electric power-assisted steering transmission mechanism and an electric power-assisted steering mechanism. The electric power-assisted steering transmission mechanism comprises a motor, a gear-worm transmission mechanism, a differential gear train mechanism, a pinion-rack transmission mechanism and a trapezoidal steering mechanism. A worn of the gear-worm transmission mechanism is driven by the motor, and a gear of the gear-worm transmission mechanism is coaxially and fixedly connected with a large sun gear of the differential gear train mechanism. A small sun gear of the differential gear train mechanism is coaxially and fixedly connected with an automobile steering shaft. A central shaft of a planet gear of the differential gear train mechanism is coaxially and fixedly connected with a pinion of the pinion-rack transmission mechanism. A rack of the pinion-rack transmission mechanism drives wheels to be steered via the trapezoidal steering mechanism. The utility model solves the technical problems that power-assisted transmission by conventional worm transmission mechanisms is hysteretic in steering and overtime in operation and steering wheels are too poor in hand feeling. With regard to the reduction in displacement and speed of rack output, the utility model facilitates speed decrease and torque increase, and enables drivers to conveniently and easily steer.

Description

A kind of electric power steering transmission device and electric boosting steering system

Technical field

The utility model relates to a kind of electric power steering transmission device and electric boosting steering system.

Background technology

Electric power steering (Electric Power Steering, EPS) system is a kind of brand new power electronics Fu, with respect to conventional hydraulic power steering (Hydraulic Power Steering, HPS) system, it has saving fuel, help environmental protection, controlledly turn to plurality of advantages such as sensation, and has adapted to New Generation of Electric Vehicle and intelligent vehicle electronization, intelligent requirements.

The servodrive mechanism design should be considered the size of steering hardware installing space on the automobile, and it is simple, compact to try one's best on the structure, forward rotation efficient height and backwards rotation efficient is suitable, and guarantee that rotor inertia, friction and gap are as far as possible little.Therefore whether servodrive mechanism rationally directly can influence the performance of whole EPS system.Some external makers make the EPS finished product at the worm and gear reduction gearing mechanism at present.(Electric Control Unit ECU) forms this scheme by electrical motor, magnetic clutch, car speed sensor, torque sensor, worm gearing and electronic control unit.The power-assisted that electrical motor provides acts on steering shaft after amplifying by the worm gearing deceleration, and driver assistance person carries out handling maneuver.When high vehicle speeds does not need power-assisted or servo-steering to break down, can in time disconnect magnetic clutch and end power-assisted purpose to reach.Because the adhesive of magnetic clutch needs the regular hour with separating all, will inevitably cause the hysteresis that turns to and overtime.When needs provide power-assisted,, cause providing power-assisted to lag behind the steering reaction overlong time owing to need the time in the attracting process.Also there is a problem in this system, and mean speed equals the output behind the motor deceleration when be difficult to guaranteeing wheel steering.This can cause the bearing circle feel poor excessively.

Summary of the invention

The utility model purpose provides a kind of electric power steering transmission device and electric boosting steering system, it adopts worm and gear-NGW differential gear train to carry out servodrive, has solved turning to that existing worm gearing carries out that servodrive brought and has lagged behind and technical matters overtime, that the bearing circle feel is poor excessively.

Technical solution of the present utility model is:

A kind of electric power steering transmission device is characterized in that: comprise electrical motor, Worm and worm-wheel gearing, differential gear train mechanism, rack-and-gear drive motor, tie rod linkage; The worm screw 1 of described Worm and worm-wheel gearing is driven by electrical motor 9; The worm gear 2 of described Worm and worm-wheel gearing and the big sun wheel of differential gear train 5 coaxial being connected; The small sun gear 3 of described differential gear train and steering axles 8 coaxial being connected; The center shaft of the satellite gear 4 of described differential gear train and the gear of rack and pinion drive mechanism 6 coaxial being connected; The tooth bar 7 of described rack and pinion drive mechanism turns to by turning to ladder type mechanism drive wheels.

A kind of electric boosting steering system comprises electric power steering transmission device and control system, and described control system comprises the speed of a motor vehicle, moment of torsion and rotary angle transmitter and electronic control unit ECU; It is characterized in that: described electric power steering transmission device comprises electrical motor 9, Worm and worm-wheel gearing, differential gear train mechanism and rack and pinion drive mechanism; The worm screw 1 of described Worm and worm-wheel gearing is driven by electrical motor 9; The worm gear 2 of described Worm and worm-wheel gearing and the big sun wheel of differential gear train 5 coaxial being connected; The small sun gear 3 of described differential gear train and steering axles 8 coaxial being connected; The center shaft of the satellite gear 4 of described differential gear train and the gear of rack and pinion drive mechanism 6 coaxial being connected; The tooth bar 7 of described rack and pinion drive mechanism is used for drive wheels and turns to; Described electronic control unit ECU according to the speed of a motor vehicle, moment of torsion and and the vehicle data that provides of rotary angle transmitter, one of control motor 9 output turn to identical auxiliary torque with the bearing circle hand-power.

The utlity model has following advantage:

1, it is consistent or approaching not need to satisfy the rotating speed of rotating speed behind the motor deceleration and bearing circle.Differential gear train mechanism has two degree of freedom, and promptly given two input motions can have definite output movement.When chaufeur turned to, different people acted on the mean speed difference on the bearing circle, and different road conditions when turning to mean speed also different.And the electrical motor of selecting can only provide the rotating speed of determining numerical value according to fixing transmitting ratio.When directly adopting the worm gearing power-assisted, then preferably require two tachometer values equal or approaching, otherwise the steering shaft life-span is reduced.Lift a simple example: people pulls a cart harder, if a guy's help is drawn together, the muscle power that then everyone paid can obviously reduce.But precondition must allow two people act in agreement, and promptly will guarantee that still the degree of freedom of car is 1 after two people's combineds action.

2, electrical motor not during power-assisted differential gear train be converted into planet circular system, reduce from the moving displacement and the speed of tooth bar output, helping slowing down increases square, has solved to make chaufeur turn to light problem.

3, worm and gear-NGW differential gear train (EPS) relies on to rotate in the train and compares α ₁, α ₂Design, make chaufeur can predict motor force shared percentum in whole load, electrical motor has overcome the load that differential gear train separates.Therefore the EPS system can improve manoeuvereability of automobile well.

When 4, the power-assisted input being arranged, under the identical bearing circle angular transposition input, rack displacement, speed are all bigger.The chaufeur problem of steering wheel rotation significantly in the time of can solving urgent big corner like this and turn to.

5, it is big to have an alerting ability, can more easily satisfy the motor turning performance demands, thereby have comparatively wide application prospect.

Feed back to the moment of bearing circle when 6, the utility model mechanism can effectively reduce non helping hand, hired roughneck's phenomenon under the power-assisted failure conditions on the actv. solution potted road surface, and make that the hand-power that feeds back on the bearing circle is level and smooth, can not cause sense of fatigue to chaufeur.

Description of drawings

Fig. 1 is a structural principle scheme drawing of the present utility model;

Fig. 2 is a structural representation of the present utility model;

Fig. 3 is a bearing circle angular transposition change curve in time;

Fig. 4 is for affacting the corner change curve of sun wheel 5 behind the motor deceleration;

Fig. 5 is for having the power-assisted hour rack along X-axis displacement and speed change curve in time;

Fig. 6 is the non helping hand hour rack along X-axis displacement and speed change curve in time;

Fig. 7 is the structural representation after the utility model and the Ackerman steering mechanism combination.

Wherein: the 1-worm screw; The 2-worm gear; The 3-small sun gear; The 4-satellite gear; The big sun wheel of 5-internally toothed annulus structure; Gear in the 6-rack and pinion steering gear; Tooth bar in the 7-rack and pinion steering gear; The 8-steering axles; The 9-electrical motor, the H-pinion carrier.

The specific embodiment

Electric boosting steering system comprises electric power steering transmission device and control system, and control system comprises the speed of a motor vehicle, moment of torsion and rotary angle transmitter and electronic control unit ECU; The electric power steering transmission device is made of electrical motor, a cover Worm and worm-wheel gearing, a cover differential gear train mechanism, set of gears rack mechanism and steering trapezium.Propulsion source is respectively electrical motor 9 and the actuating force that affacts on the bearing circle.The small sun gear 3 of differential gear train is contained in and turns on the input shaft, promptly on the steering axles.Big sun wheel 5 and worm gear 2 are coaxial.Therefore electrical motor drives big sun wheel 5 motions through the one-level worm gear box.Two inputs of differential gear train are respectively bearing circle moment from small sun gear 5 inputs, and electrical motor power-assisted square is from big sun wheel 5 inputs, and synthetic motion is exported by pinion carrier H.Its principle of work is according to vehicle data such as the speed of a motor vehicle, moment of torsion and wheel steering angle sizes, electronic control unit ECU provides one to turn to identical auxiliary rotating torque with the bearing circle hand-power according to depositing definite control policy driving motor in advance in, and utilizes the synthetic front-wheel steering angle that obtains of motion of differential gear train.Adopt this scheme, reduced the transmitting ratio of steering swivel system indirectly, thereby reduced the manual steering angle, and then reduce the merit that turns to of chaufeur consumption.When the electric weight deficiency, when promptly needing to adopt the manual steering condition because worm gearing is designed to the reversing sense self-locking mechanism, so the time big sun wheel 5 take turns fixing.Worm gearing is not worked in such cases, and differential gear train mechanism is converted into planetary wheel mechanism.Handling maneuver drives small sun gear 5 from bearing circle and rotates as input, and big sun wheel 5 is motionless, and motion is still exported from pinion carrier H.

The utility model principle:

1, worm and gear-NGW differential gear train motion analysis

If the rotating speed of small sun gear 5 is n ₃, the rotating speed of big sun wheel 5 is n ₅, the rotating speed of pinion carrier H is n _H, the number of teeth of small sun gear 5,5 is respectively Z ₃, Z ₅, moving by the differential gear system than having:

$i_{35}^H=\frac{n_3-n_H}{n_5-n_H}=-\frac{Z_5}{Z_3}---\left(1\right)$

Put in order:

$n_H=\frac{Z_3}{Z_3+Z_5}{n}_3+\frac{Z_5}{Z_3+z_5}{n}_5---\left(2\right)$

Know that from formula (2) rotating speed of pinion carrier H is that the steering shaft rotating speed is arrived in the front-wheel equivalence in this scheme, its value is synthetic for manual steering speed and motor speed, and obviously, this scheme has two degree of freedom, as manual steering rule n ₃Determine, and motor speed is when changing, the front-wheel steering speed that obtains after synthetic also changes thereupon, therefore can obtain different steering swivel system output speed n by the rotating speed of adjusting electrical motor independently _H, be adjustable so turn to sensitieness under the scheme.When electrical motor power-assisted not, during promptly pure manual steering, big sun wheel 5 is motion (n not ₅=0), at this moment:

$n_H=\frac{Z_3}{Z_3+Z_5}{n}_3---\left(3\right)$

As seen from formula (3), because the deceleration effort of differential gear train, transmitting ratio was less than 1: 1 when making pure manual steering, thereby the manual steering sensitieness descends, this is unfavorable to the safety of high vehicle speeds lower-pilot, and this solves by the output speed of adjusting electrical motor with regard to requiring, so can increase energy consumption.Make in the formula (2):

${\mathrm{\&alpha;}}_1=\frac{Z_3}{Z_3+{\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="DEST\_PATH\_HDA0000071794450000032.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5}$ ${\mathrm{\&alpha;}}_2=\frac{Z_5}{Z_3+{\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="DEST\_PATH\_HDA0000071794450000032.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5}$

And be that 0 integration gets to the following formula initialization:

θ _H＝α ₁θ ₃+α ₂θ ₅ (4)

Know by the front input: θ ₃=θ _h, θ ₅=θ ₂=θ _m/ G gets its substitution formula (4):

θ _H＝α ₁θ _h+α ₂θ _m (5)

Can get the statics equation by the principle of virtual displacement:

$\left\{\begin{array}{c}{\mathrm{\&tau;}}_H={\mathrm{\&tau;}}_h+{\mathrm{\&tau;}}_m\\ {\mathrm{\&tau;}}_m={\mathrm{\&alpha;}}_2{\mathrm{\&tau;}}_H\\ {\mathrm{\&tau;}}_h={\mathrm{\&alpha;}}_1{\mathrm{\&tau;}}_H\end{array}\right.---\left(6\right)$

Can see that from kinematical equation formula (4) angular transposition of output pivoted arm H is the stack of small sun gear and motor angle position.Here α ₁, α ₂Be that gear rotates ratio, they are determined jointly by the sun wheel number of teeth, the satellite gear number of teeth and the center gear number of teeth.θ _HBe the output corner of differential gear train, θ ₃, θ ₅, θ ₂Represent sun wheel 3 respectively, the corner of sun wheel 5 and worm gear 2, θ _h, θ _mBe respectively bearing circle and electrical motor input corner.τ _h, τ _mAnd τ _HThe virtual displacement of representing bearing circle, electrical motor and pinion carrier H respectively.With the electrical motor rotational angle theta _mAs the function of the chaufeur corner and the speed of a motor vehicle, establishing the electrical motor DC current gain is K _b, it is as follows to get the stable state equation of change:

θ _m＝K _b·f(θ _h)·f(V) (7)

By the quiet equation (6) of gear train as can be known, there is similar statics feature in system to the manual steering system.Differential gear train relies on and rotates transmitting ratio α in the train as a moment of torsion disengagement gear ₁, α ₂Design, make the chaufeur can predict motor force shared percentum in whole load, electrical motor has overcome the load that differential gear train separates, and makes it turn to definite position.Therefore, differential gear train is actually another kind of work-saving device, and it reduces the load transmitted from rack pinion, thereby it is light to make that chaufeur turns to.

2, dynamics analysis

The center gear of wheel steering axle and differential gear train is done as a whole, front-wheel and pinion carrier are done as a whole, and the cornering resistance of front-wheel and rotor inertia equivalence are carried out dynamics analysis to steering shaft to it, can obtain following kinetic model:

$\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}_{\mathrm{<figure-callout\; id="1"\; label="h\; J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">h</figure-callout>}}^{J_{}}{}_{{}_1}+{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1{\stackrel{\&CenterDot;}{\mathrm{\&theta;}}}_h+J_2{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}}_h+b_2{\stackrel{\&CenterDot;}{\mathrm{\&theta;}}}_h=T_h-{\mathrm{\&alpha;}}_1{T}_r---\left(8\right)$

${}_{J_2}\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}_h+b_3{\stackrel{\&CenterDot;}{\mathrm{\&theta;}}}_h+J_3{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}}_m+{\mathrm{<figure-callout\; id="4"\; label="b"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">b</figure-callout>}}_4{\stackrel{\&CenterDot;}{\mathrm{\&theta;}}}_m=T_m-{\mathrm{\&alpha;}}_2{T}_r---\left(9\right)$

Formula (8) but be the non-secondly differential equation of the second order of a depression of order, wherein do not contain θ _h, in addition Then the following formula deformable is

$({\mathrm{<figure-callout\; id="1"\; label="J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">J</figure-callout>}}_1+J_2)\stackrel{\&CenterDot;}{X}+(b_1+b_2)X=T_h-{\mathrm{\&alpha;}}_1{T}_r---\left(10\right)$

Utilize the non-secondly differential equation general solution of single order to get:

$x=e^{-\frac{(b_1+b_2)\mathrm{<figure-callout\; id="1"\; label="t\; J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">t</figure-callout>}}{J_{}}}(\&Integral;\frac{T_h\left(t\right)-{\mathrm{\&alpha;}}_1{T}_r\left(t\right)}{{\mathrm{<figure-callout\; id="1"\; label="J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">J</figure-callout>}}_1+J_2}\&CenterDot;e^{\frac{(b_1+b_2)\mathrm{<figure-callout\; id="1"\; label="t\; J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">t</figure-callout>}}{J_{}}}\mathrm{dt}+C)---\left(11\right)$

The X integration is got:

${\mathrm{\&theta;}}_h=\&Integral;e^{-\frac{({\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+b_2)\mathrm{<figure-callout\; id="1"\; label="t\; J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">t</figure-callout>}}{J_{}}}(\&Integral;\frac{T_h\left(t\right)-{\mathrm{\&alpha;}}_1{T}_r\left(t\right)}{{\mathrm{<figure-callout\; id="1"\; label="J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">J</figure-callout>}}_1+J_2}\&CenterDot;e^{\frac{(b_1+b_2)\mathrm{<figure-callout\; id="1"\; label="t\; J"\; filenames="DEST\_PATH\_HDA0000071794450000011.png"\; state="\{\{state\}\}">t</figure-callout>}}{J_{}}}\mathrm{dt}+C)\mathrm{dt}---\left(12\right)$

In like manner equation (9) but also be the differential equation of a depression of order, with what solve above

Substitution can obtain θ _mExpression formula:

${\mathrm{\&theta;}}_m={\&Integral;e}^{-\frac{b_4}{J_3}\&CenterDot;t}(\&Integral;\frac{T_m\left(t\right)-{\mathrm{\&alpha;}}_2{T}_r\left(t\right)-J_2{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}}_h-b_3{\stackrel{\&CenterDot;}{\mathrm{\&theta;}}}_h}{J_3}\&CenterDot;e^{\frac{b_4}{J_3}\&CenterDot;t}\mathrm{dt}+C)\mathrm{dt}---\left(13\right)$

Wherein, J ₁Be rotary inertia of steering wheel, J ₂Be sun wheel 3 rotor inertias, J ₃Rotor inertia for satellite gear.b ₁Be bearing circle damping coefficient, b ₂Be sun wheel 3 damping coefficients, b ₃Be satellite gear damping coefficient, b ₄Damping coefficient, θ for pinion carrier _hBe steering wheel angle, θ _mThe corner of electrical motor, T _hFor turning to hand-power square, T _mElectrical motor power-assisted square, T _rBe the wheel steering resisting moment.By formula (8), (9) as can be known, the power-assisted that electrical motor provides must overcome α ₂Steering resisting torque doubly could change self cireular frequency and angular acceleration, and then the steering handwheel hand-power is exerted an influence, and this influence is at J ₂, b ₂Under the less situation and not really remarkable, and always some cornering resistance according to fixing α ₁Multiple is assigned on the hand-power.So under this transmission device scheme, vehicle can both guarantee to turn to the existence of hand-power when any speed of a motor vehicle is travelled, promptly turn to the existence of " feel " ^{[5] [6]}The electrical motor rotational angle theta has further been verified in formula (12), (13) _mShould be with steering wheel angle θ _hChange this rule, visible θ _h, θ _mTwo parameters not only and T _h, T _rTwo variablees are about also relevant with the constant of decision such as system architecture.

The utility model Fig. 3 and Fig. 4 have provided bearing circle at given input motion, electrical motor have assist exercise and and non helping hand when motion, the moving displacement of output tooth bar and the change curve of speed.Displacement in the straight-line motion on the emergency turn hour rack and velocity curve, getting direction, to fold the rank time be 0.2 second, maximum angular displacement 72 degree, it is 0.4 second that electrical motor plays the rank time, and maximum angular displacement is 186 degree, and the variation in angular displacement curve is as shown in Figure 3 and Figure 4.Fig. 3,4 abscissa are all represented unit of time second, and ordinate is all represented the angular unit radian.

Above-mentioned input represents that bearing circle received the input of corner suddenly in preceding 0.2 second, and corner is 0 degree in the time of the 0th second, corner 72 degree in the time of the 0.2nd second, and not input At All Other Times is not so the angular transposition curve changed promptly parallel and abscissa after 0.2 second.In like manner affact the corner on the sun wheel 5 behind the motor deceleration, received a corner input suddenly in preceding 0.4 second, the 0th second corner is 0 degree, and corner reached 186 degree in the 0.4th second.Tooth bar output displacement and velocity curve are as shown in Figure 5 and Figure 6.Solid line among Fig. 5 represents that rack displacement changes in time, and dotted line represents that tooth bar speed changes in time.When electrical motor not during power-assisted, bearing circle is equally with above-mentioned Step function input, affacts displacement on the tooth bar and velocity curve as shown in Figure 6.

Comparison diagram 5 and Fig. 6 import with definite movement relation when bearing circle as can be known, and the displacement and the speed generation significant change of tooth bar under two kinds of situations of power-assisted and non helping hand are arranged.Bearing circle and electrical motor movement relation are as previously mentioned in the literary composition, by figure (5) know when electrical motor with the jump function power-assisted, and reach maximum 186 when spending at 0.4 second assisted electric machine corner, maximum displacement is 31mm on the tooth bar, do not move since 0.4 second tooth bar, its displacement does not change in time.Become big gradually and then be reduced to 0mm/s from little earlier at whole process medium velocity, know speed in the 0.15s maximum by Fig. 6, its value is 116.7mm/s.Known when electrical motor power-assisted not by Fig. 6, and the bearing circle rule is when constant, tooth bar reaches maximum displacement in 0.2 second, and its maximum displacement is 3.8mm only.Maximum speed appears at 0.1s, and maxim is 29.1mm/s.Relatively two kinds of situations can obviously be seen, according to input mode in the literary composition, and not about 1/8 when not having the displacement of power-assisted hour rack only for power-assisted, speed is about 1/4 when power-assisted is arranged.Know that by above analysis when the bearing circle characteristics of motion was constant, the variation of electrical motor assist exercise rule directly influenced the time that the moving velocity maxim occurs on the tooth bar.Therefore can obtain different tooth bar speed change curves by the assist exercise rule of adjusting the electrical motor input in actual applications, thereby satisfy the various requirement in the steering procedure ^[8]Above-mentioned curve shows is introduced differential gear train mechanism in transmission device, can not only finish the displacement that the wheel steering hour rack should move in a short period of time, and can adjust electrical motor assist exercise rule by control system and reach the requirement that turns to that adapts to flexibly under the different situations.

Claims (2)

1. an electric power steering transmission device is characterized in that: comprise electrical motor, Worm and worm-wheel gearing, differential gear train mechanism, rack-and-gear drive motor, tie rod linkage; The worm screw of described Worm and worm-wheel gearing is by direct motor drive; Coaxial being connected of big sun wheel of the worm gear of described Worm and worm-wheel gearing and differential gear train; The small sun gear of described differential gear train is connected with steering axles is coaxial; The center shaft of the satellite gear of described differential gear train is connected with the gear of rack and pinion drive mechanism is coaxial; The tooth bar of described rack and pinion drive mechanism turns to by turning to ladder type mechanism drive wheels.

2. an electric boosting steering system comprises electric power steering transmission device and control system, and described control system comprises the speed of a motor vehicle, moment of torsion and rotary angle transmitter and electronic control unit; It is characterized in that: described electric power steering transmission device comprises electrical motor, Worm and worm-wheel gearing, differential gear train mechanism and rack and pinion drive mechanism; The worm screw of described Worm and worm-wheel gearing is by direct motor drive; Coaxial being connected of big sun wheel of the worm gear of described Worm and worm-wheel gearing and differential gear train; The small sun gear of described differential gear train is connected with steering axles is coaxial; The center shaft of the satellite gear of described differential gear train is connected with the gear of rack and pinion drive mechanism is coaxial; The tooth bar of described rack and pinion drive mechanism is used for drive wheels and turns to; Described electronic control unit according to the speed of a motor vehicle, moment of torsion and and the vehicle data that provides of rotary angle transmitter, one of control motor output turns to identical auxiliary torque with the bearing circle hand-power.

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