KR19980076895A - Automotive Electronic Power Steering - Google Patents

Abstract

The present invention is an electronic power steering device in which power steering operation is stopped and the built-in components are not overwhelmed when driving on an irregular road surface or during maximum steering.

The present invention, the steering motor (1) driven by the operation of the steering wheel 101, the forward rotation unit 2 and the reverse rotation unit (3) for receiving the rotational force from the steering motor (1) to generate the rotational force in the opposite direction to each other Connection means (5) for selectively connecting any one of the forward rotation portion (2) or the reverse rotation portion (3) to the steering shaft (102) corresponding to the operating means of the transmission means 4, the steering wheel (101) including Switching means 6 for applying a drive signal to the steering motor 1 during the operation of the steering wheel 101 and at the same time applying a selective connection signal to the connecting means 5 corresponding to the operating direction of the steering wheel 101. In an electronic power steering apparatus for automobiles, the torque between the drive shaft (1a) and the steering shaft (102) is constant on the power transmission path from the drive shaft (1a) to the steering shaft (102) of the steering motor (1). Overload protection means (7) to cut off power if larger than the size, or steering to the left or right The maximum is detected immediately before the point at which will be characterized by including a power cut-off means (8) for selectively blocking off the connection means (5) corresponding to the steering direction.

Description

Automotive Electronic Power Steering

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic power steering apparatus for automobiles. More specifically, in steering operation of a steering apparatus, steering wheels are operated and additional steering force is added to the steering shaft to facilitate steering operation of the driver. An electronic power steering device is provided.

The power steering device of a vehicle is usually composed of hydraulic type. The hydraulic power steering device includes an oil pump as a hydraulic power source, a hydraulic actuator that generates steering force by converting hydraulic pressure from the oil pump into mechanical force, and a steering wheel. It consists of a control unit that controls the operation of the hydraulic actuator by selectively opening and closing the flow path from the oil pump to the hydraulic actuator by operation, and various other components to ensure accurate operation.

Therefore, the hydraulic power steering system as described above requires a relatively complicated mechanical configuration, so that the weight increase of the vehicle body is inevitable, and there is a problem in manufacturing cost increase and securing the installation space. There was also discomfort.

Therefore, a large number of electronic power steering devices have been introduced in which oil pumps, hydraulic actuators, and the like in such hydraulic power steering devices are replaced with steering motors.

Japanese Patent Laid-Open Nos. 83-202803 and 84-70257 show typical types of such electric power steering devices, and the electronic power steering device according to the contents disclosed in this publication is connected to a steering link or a steering shaft. It consists of a steering motor, a torque sensor for detecting the torque of the steering wheel, a speed sensor for detecting the vehicle driving speed, and a control unit for variably controlling the torque of the steering motor by the information obtained from each sensor.

However, such a conventional electric power steering device has some fatal problems as follows.

First, the possibility of malfunction during steering is very high. For example, due to the influence of the power supply and / or torque sensor, an unexpected steering operation against the driver could occur because the voltage applied to the circuit is not constant.

Second, due to the variable resistor used to variably adjust the torque of the steering motor, the possibility of damaging the entire circuit is very high. In this case, the steering ability may be lost, resulting in a serious risk situation.

Third, since the steering motor rotates with the steering wheel, it is structurally difficult to return the steering wheel and the steering shaft to the straight position after the steering is completed (returnability). A separate circuit had to be provided.

Due to various problems of the electric power steering apparatus as described above, which is not solved up to now, despite its advantages in its simple configuration and light weight, it is not widely used yet.

On the other hand, the applicant has filed an electronic power steering device (Patent Application No. 93-15733, Patent Application No. 94-333) on August 14, 1993 and January 11, 1994, respectively.

However, in the above-mentioned patent application No. 93-15733, although all the problems in the aforementioned electric power steering apparatus have been solved, it is considered that there is a problem in steering response due to the rotational inertia of the steering motor. In other words, the delay of operation response time could be caused due to the rotational inertia of the steering motor during steering operation. Therefore, it was not possible to guarantee perfect operation stability in case of delicate steering operation or emergency situation.

Patent application No. 94-333, which solves this problem, can improve the steering responsiveness by changing the transmission structure between the steering motor and the steering shaft at the same time as always the direction of rotation of the steering motor.

However, the two previously applied power steering apparatuses overload the steering motor and / or the gears that transmit the driving force of the steering motor to the steering shaft when driving on an irregular road surface or at the maximum steering in one direction, so that the steering is stable. Not only did not perform the function but also had a problem in reducing the endurance life of the steering motor and gears.

That is, when driving on an irregular road, when the wheel is impacted from the road surface, the impact is transmitted to the steering shaft through the steering link, and the steering wheel moves left and right. If the switching means sends a steering signal in the opposite direction to drive the steering motor in the direction opposite to the rotation direction of the steering wheel. However, since the steering shaft is constrained by the driver, a torsional stress is generated in the power transmission path between the steering shaft and the steering motor, and mechanical shock is applied to the gears. In addition, since the steering motor is not driven while being supplied with power, an overcurrent flows instantaneously and overheats.

In the conventional power units, the steering means continuously supplies power to the steering motor by providing a steering signal when the steering is at maximum steering, whereas the steering link is no longer moving, as in the impact on the road surface. An overcurrent flows through and causes a strain. Therefore, there was a problem of greatly shortening the endurance life of gears and steering motors that perform power transmission.

Therefore, the present invention solves the problems of the electronic power steering apparatus of the conventional vehicle as described above, the steering motor and steering when a torsional stress of a predetermined size or more occurs in the power transmission path from the steering motor to the steering shaft It is an object of the present invention to provide an electronic power steering apparatus for a vehicle including an overload prevention means capable of cutting off the power acting between the axes, or a power cutoff means for detecting power when the steering is turned off to cut off the power to the steering motor.

1 is a schematic view showing the configuration of an electronic power steering apparatus for a vehicle according to an embodiment of the present invention.

Figure 2 is a perspective view showing an example of the switching means in the present invention.

3A is a longitudinal cross-sectional view of FIG. 2.

3B is a cross-sectional view of FIG. 3.

Figure 4 is a front view showing a power transmission system in the present invention.

5 is a plan view of FIG. 4.

Figures 6a and 6b is an operation showing the forward and reverse power transmission path of FIG.

Figure 7 is an exploded perspective view showing an example of the overload prevention means in the present invention.

8 is a perspective view showing an example of the steering angle detection means in the present invention.

9A is a schematic diagram showing an example of a power cutoff means in the present invention;

9b and 9c show the operation of Fig. 9a;

Figure 10 is a schematic diagram showing another example of the power cutoff means in the present invention.

11A, 11B, 11C are operational views of FIG. 10.

12 is a schematic view showing still another example of the power cut-off means in the present invention.

13A and 13B show the operation of FIG. 12.

Explanation of symbols on the main parts of the drawings

1: Steering Motor 2: Forward Rotating Part

3: reverse rotation 4: power transmission means

5 connection means 6 switching means

11: drive gear 12: first main gear

13: 1st driven gear 14: 2nd main gear

15: 2nd driven gear 16: gear housing

17, 18: electromagnet assembly 22: steering sensor

23: switching rod 24, 25: steering limit switch

31: external axis 32: internal axis

33: steering shaft housing 36: lever

37: guide portion 38, 39: switch

40: elastic member 41: torsion coil spring

101: steering wheel 102: steering shaft

103: steering link 104: steering gear

The present invention for achieving the above object is applied to a steering device in which a steering shaft is rotated in conjunction with a steering wheel arbitrarily manipulated by a driver, and the steering wheel is steered by a steering link moved left and right by the rotation of the steering shaft. A steering motor driven by operation of the steering wheel, transmission means including a forward rotation part and a reverse rotation part which receive rotational force from the steering motor and generate rotational forces in opposite directions, respectively, and in the operation direction of the steering wheel. Corresponding connecting means for selectively connecting either the forward rotation part or the reverse rotation part to the steering shaft, and applying a drive signal to the steering motor when the steering wheel is operated, and correspondingly corresponding to the steering direction of the steering wheel. An electronic power steering apparatus for automobiles comprising switching means for applying an optional connection signal to said connection means. On, and the drive shaft of the steering motor characterized in that it comprises an overload protection means of the torque acting between the drive shaft and the steering shaft to block the power when more than a predetermined size on the power transmission path to the steering shaft.

Hereinafter, a preferred embodiment of the present invention having the above configuration will be described in more detail with reference to the accompanying drawings.

In the description of the present embodiment, the description of the configuration of the present invention, which is the same as the conventional technology described at the outset, will be mainly omitted for the sake of clarity and only improved parts.

First, briefly look at the drawings, Figure 1 is a schematic diagram showing the overall configuration of the present invention, Figures 2 to 13 shows the structure of each configuration of FIG.

As shown in FIG. 1, the steering device of a vehicle includes a left / right side of a vehicle in which a steering link 103, which receives a rotational force of a steering wheel 101 arbitrarily manipulated by a driver, moves through the steering shaft 102 from side to side. It is a device to change the steering angle of the right wheel.

The power steering apparatus of the present invention applied to such a steering apparatus, in the steering operation of the steering apparatus, is a device that assists the steering operation convenience of the driver by adding a separate steering force to the steering wheel operation force during the steering operation of the driver.

The power steering apparatus according to the present invention has a power transmission system for generating steering force added to two systems, namely, steering devices during steering operation, and a power supply direction for driving the power transmission system, and steering direction. It is roughly divided into an electric control system that controls.

First, looking at the power transmission system, as shown in Figure 1, the steering motor 1, the steering force of the steering motor 1 can be transmitted to the steering shaft 102 in the forward or reverse rotation direction according to the steering direction. It can be seen that it is composed of a transmission means (4).

The steering motor 1 is an electric motor that generates steering force added to the driver's steering wheel 101 operation force by the driver's steering operation.

As shown in FIGS. 4 and 5, the transmission means 4 is a gear assembly that transmits the rotational force of the steering motor 1 to the steering gear 104 integrated with the steering shaft 102. It is divided into a forward rotation part (2) and a reverse rotation part (3) which transmits the rotational force of the steering motor (1) to the steering shaft (102) in opposite directions, which are fixed integrally by the gear housing (16).

The forward rotational portion 2 is engaged with the drive gear 11 of the steering motor 1 and rotates with the first main gear 12 and the first driven gear 13 integrated on the same axis as the first main gear 12. And the reverse rotation unit 3 is a second driven gear 15 integrated in the same axis as the second main gear 14 rotated in engagement with the first main gear 12 of the forward rotation unit 2. It is composed.

In addition, the gear housing 16 accommodates the gears of the forward rotation part 2 and the reverse rotation part 3 to be integrally fixed, and is fixed to the outer case of the electric power steering apparatus to be detachably coupled to the steering gear. The hinge portion 16a is pivotally pivoted about an axis within the angle range.

With this configuration, the transmission means 4 is the first driven gear 12 of the forward rotation part 2 as the gear housing 16 is rotated about the hinge portion 16a as shown in Figs. 6A and 6B. Or the second driven gear 14 of the reverse rotation unit 3 selectively engages the steering gear 104 of the steering shaft 102 to transfer the forward rotational force of the steering motor 1 in the forward or reverse direction.

On the other hand, the drive shaft 1a of the steering motor 1 is provided with a multi-plate friction clutch as shown in the exploded perspective view of FIG. The clutch is connected only when the torque acting on the drive shaft is equal to or less than a certain size to transmit the driving force of the steering motor 1 to the drive gear. Therefore, when an excessive load is applied to the drive shaft, the clutch is slid so that the gear and the steering motor 1 do not have a large force of a predetermined torque or more.

In the electric control system, as shown in FIG. 1, the switching means 6 which applies a current by sensing the manipulation of the steering wheel largely, and the transmission means 4 to the steering gear in response to the application of the current of the switching means 6. Connection means 5 for connecting, and in addition to the present embodiment, a configuration such as a power cut-off means 8 for cutting off the current applied by the switching means 6 to the connection means 5 during maximum steering. Is done.

The switching means 6 is an outer shaft 31 rotatably installed in the steering shaft housing 33, as shown in FIGS. 2, 3A and 3B, and rotatably installed in the outer shaft 31. And an inner shaft 32 on which the steering wheel 101 is mounted at an upper end thereof, installed on an outer circumference of the inner shaft 32, a lever 36 rotated together with the inner shaft 32, and an outer shaft for guiding movement of the lever 36. Two switches 38 which are installed at both ends of the guide part 37 and the guide part 37 of the 31 and apply a driving signal to the electric motor 1 at the same time and generate different signals at the same time. 39, an elastic member 40 for elastically supporting the inner shaft 32 with respect to the outer shaft 31, and a torsion coil spring 41 for elastically supporting the inner shaft 32 with respect to the steering shaft housing 33. Consists of.

In such a configuration, the switching means 6 operates as follows.

When the steering wheel 101 is arbitrarily manipulated by the driver, the inner shaft 32 is rotated. If the rotational force of the inner shaft 32 is greater than the elasticity of the elastic member 40 and the stroke is greater than the length of the guide portion 37, the inner shaft 32 is rotated by the lever 36, the outer shaft 31, At this time, the lever 36 selectively operates any of the switches 38 and 39 corresponding to the rotational direction of the guide portion 37 of the outer shaft 31. The selected switches 38 and 39 transmit driving signals to the steering motor 1 and apply power to the circuits of the connection means 5. As described above, the switching means 6 operates the switches 38 and 39 corresponding to the rotation direction of the steering wheel, that is, the steering direction of the driver, as the steering wheel 101 is operated to supply current to the steering motor 1. At the same time, power is applied to the connecting means 5 corresponding to the steering direction.

As shown in FIG. 5, the connecting means 5 includes two electromagnet assemblies 17 and 18 corresponding to the left and right steering directions and an elastic member 19 installed on the rear surface of the gear housing 16. have. Each of the electromagnet assemblies 17 and 18 is fixed to an outer case 20 fixed to the vehicle body, and any one of the electromagnet assemblies 17 and 18 is operated by a power source selectively applied by the switching means 6 to the gear housing 16 of FIGS. As shown in FIG. 6B, the first driven gear 13 of the forward rotating part 2 of the transmission means 4 or the second driven gear 15 of the reverse rotating part 3 is rotated in either direction. ) Is connected to the steering gear 104. When the applied power is cut off, the electromagnet assemblies 17 and 18 lose their magnetic force and the gear housing 16 is restored to its original position in the gear neutral state by the elasticity of the elastic member 19.

And, as shown in FIG. 8, the power cut-off means 8 additionally included in the connecting means 5 of the present embodiment, the steering gear 104 is fixed to the outer case 20 by the bracket 21. The steering angle sensor 22 rotates in engagement with (), the switching rod 23 screwed in the longitudinal direction of the steering angle sensor 22, and, as shown in Figure 9a, of the switching rod 23 It is composed of two left and right steering limit switches 24 and 25 provided with both ends and predetermined intervals to control the current flowing through the electromagnet assemblies 17 and 18.

The steering angle sensor 22 rotates by being engaged with the steering gear 104 to deviate the switching rod 23 by a distance proportional to the amount of rotation of the steering gear 104, that is, the steering angle. When the eccentricity reaches a predetermined amount, the switching is performed. The rod 23 selectively shorts any one of the left and right steering limit switches 24 and 25. The short circuit by this switch rod 23 is performed just before the maximum steering angle.

Hereinafter, the present embodiment includes the configurations as described in detail above, that is, the steering motor 1 and the transmission means 4 of the power transmission system, and the switching means 6 and the connection means 5 of the electric control system. Let's look at the process of the example power steering.

First, when the steering wheel 101 is arbitrarily operated by the driver, the inner shaft 32 is rotated to rotate the outer shaft 31 through the lever 36. At this time, while the stress accumulated in the elastic member 40, the lever 36 selectively operates the switches 38, 39 on the outer side corresponding to the rotational direction. The selected switches 38 and 39 send driving signals to the steering motor 1 to drive them, and also apply power to the electromagnet assemblies 17 and 18 of the corresponding connection means 5 so that the forward rotation part of the transmission means 4 is rotated. (2) or the reverse rotation unit 3 is selectively connected to the steering gear 104 of the steering shaft 102. Accordingly, the steering shaft 102 receives the rotational force of the steering motor 1 in the corresponding steering direction through the selected forward rotation part 2 or the reverse rotation part 3. Therefore, the driver receives steering force from the steering motor 1 together with the steering wheel 101 operation, so that steering can be performed more easily.

Then, when the driver releases the steering force of the steering wheel 101 in order to bring the driving state straight, the connection of the selected switches 38 and 39 is short-circuited to power the steering motor 1 and the electromagnet assembly 17 and 18. The supply is cut off. Accordingly, the steering motor 1 stops operating, and at the same time, the electromagnet assemblies 17 and 18 lose the operating force, so that the gear housing 16 is restored to the gear neutral state by the elasticity of the elastic member 19. Thus, the connection to the steering shaft of the transmission means 4 is released.

In the steering operation of the power steering device, the overload preventing means 7 acts as follows to prevent damage to the power transmission system, that is, the transmission means 4 and the steering motor 1, which is shown in FIG. See Figure 2 and easily.

For example, when driving on an irregular road surface, the steering apparatus receives an impact in a specific steering direction from the road surface through transmission paths such as a wheel, a steering link 104, and a steering shaft 102. If the driver grips the steering wheel 101 in such a situation, the outer shaft 31 is rotated relative to the inner shaft 32 while the inner shaft 32 remains intact. Therefore, the switches 38 and 39 corresponding to the directions opposite to the steering of the wheels among the switches 38 and 39 provided on the outer shaft 31 are operated by the lever 36 of the inner shaft 32 to operate the steering motor 1. And applying power to the connecting means (5). In this case, the steering motor 1 receives power to transmit the driving force to the steering shaft 102. The instantaneous reverse steering force generated by the irregular road surface is very strong, such that the steering motor 1 and the steering shaft 102 are strong. The power transmission system in between is overloaded. At this time, since the power of the drive shaft of the steering motor 1 is limited to a predetermined torque or less by the multi-plate friction clutch, which is an overload preventing means 7, damage to the power transmission system is prevented, and overcurrent flows through the steering motor 1. Is prevented.

In addition, the function of the power cut-off means 8 added to the present invention will be described with reference to the drawings 8 and 9a to 9c.

When the driver performs the maximum steering operation in either direction, the steering shaft 102 is already rotated to the maximum while the steering motor 1 is driven with power continuously. In this case, the steering angle sensor 22, which is rotated in an amount proportional to the steering angle by the steering gear 104 immediately before the maximum steering angle, causes the switching rod 23 to be eccentric to a state as shown in FIG. 9B or 9C, and thus the current steering angle. Shut off the power corresponding to stop the steering motor (1). Therefore, the power cut-off means 8 of the present invention increases the operating efficiency by preventing power steering in a state in which steering angle is already maximized and no further power steering is necessary, thereby improving the operating efficiency of the power transmission system including the steering motor 1. Improves durability by reducing unnecessary operation of devices.

On the other hand, Figure 10 is a preferred embodiment of the power cut-off means 8 described above, the elastic member (23a, 24a, 25a) is installed on the switching rod 23 and the left and right steering limit switch (24, 25) operating part And in the middle of the hanging jaw is installed.

When the steering device is steered by the driver at maximum, the steering limit switches 24 and 25 are shorted as shown in FIG. 11B through the process of FIG. 11A so that no further power steering is achieved. At this time, the steering shaft is slightly restored in the straight direction by the torsional stress of the tire to restore the switch rod 23. In this case, the steering members 24 are moved as the elastic members 23a and 24a are displaced as shown in FIG. 11C. By maintaining the short circuit condition, the power steering is not performed again. This is to solve this problem in the simple contact structure of FIGS. 9A, 9B, and 9C because the steering device is vibrated by repeated power interruption during the maximum steering and control of the steering limit switches 24 and 25.

12 shows an example in which left and right steering limit switches 24 and 25 are provided on the steering link 103 as another embodiment of the power interruption means 8. 13A and 13B, the steering limit switches 24 and 25 are short-circuited by the gearbox 105 when the steering link 103 is moved left and right.

In this way, the power cutoff means 8 can be installed anywhere where it is displaced in proportion to the steering angle.

According to the present invention as described in detail above, when the road driving on the irregular road surface and the maximum steering angle operation, the overload of the power transmission system is not overloaded, and the overcurrent does not flow to the steering motor, so that their durability is greatly improved and the conventional power steering is improved. Compared to the device, the service life is greatly extended.

In addition, since the power of the switching means for steering in the corresponding direction in the situation where the steering device is steered to the maximum and the steering shaft is no longer power steering, the steering motor at the time of maximum steering with no further steering is suppressed. Over current can be prevented from flowing. Therefore, the endurance life of the steering motor can be further extended.

As the present invention can be variously modified by those skilled in the art without departing from the scope of the claims claimed in the claims, the technical protection scope of the present invention is the specific preferred embodiment described above It is not limited to the example.

Claims (8)

The steering shaft is rotated in conjunction with a steering wheel arbitrarily manipulated by a driver, and is applied to a steering apparatus that steers the wheel by a steering link that is moved left and right by rotation of the steering shaft. A steering motor driven by operation of the steering wheel; A transmission means including a forward rotation part and a reverse rotation part which receive rotational force from the steering motor and generate rotational forces in opposite directions, respectively; Connecting means for selectively connecting any one of the forward rotation part and the reverse rotation part to the steering shaft in correspondence to an operation direction of the steering wheel; In the electronic power steering apparatus for a vehicle comprising a switching means for applying a drive signal to the steering motor at the time of operation of the steering wheel and at the same time the selective connection signal corresponding to the steering direction of the steering wheel to the connecting means. , And an overload preventing means for blocking a torque of a predetermined magnitude or more acting between the driving shaft and the steering shaft on a power transmission path from the driving shaft of the steering motor to the steering shaft. The method according to claim 1, The overload preventing means includes an electric power steering device that cuts off power when the torsional stress applied between the drive shaft and the main gear between the drive shaft and the main gear of the steering motor is greater than or equal to a predetermined value. The method according to claim 1, And an electric power cut-off means for detecting the power supply of the steering means to detect the steering angle immediately before the steering angle to the left or the right is maximized. The method according to claim 3, The power cut off means, A steering angle sensing gear rotated in engagement with a steering gear of the steering shaft and fixed to a vehicle body; A switching rod linearly linked to the steering angle sensing gear; When the switching rod at both ends of the switching rod is more than a certain amount of eccentricity, the switching rod is short-circuited by the switching rod, characterized in that it comprises a left and right steering limit switch to cut off the power of the connecting means for steering at a steering angle corresponding to the eccentricity Electronic power steering for automobiles. The method according to claim 3, The power cut off means, It is installed at both ends of the gearbox for moving the steering link to the left or right by the rotational force of the steering shaft at the lower end of the steering shaft, the steering angle corresponding to the eccentricity when the amount of eccentricity to the left or right of the steering link is more than a predetermined Electronic power steering device for a vehicle comprising a left and right steering limit switch for shutting off the power of the connecting means for steering. The method according to claim 4 or 5, The left and right steering limit switch is short-circuited through the elastic member, so that when the left and right steering limit switch is shorted by the switching rod / gear box, between the switch rod / gear box and the left and right steering limit switch. An electronic power steering apparatus for a vehicle, characterized in that a short circuit is maintained even when a relative movement of a predetermined level or less occurs. The steering shaft is rotated in conjunction with a steering wheel arbitrarily manipulated by a driver, and is applied to a steering apparatus that steers the wheel by a steering link moved left and right by rotation of the steering shaft. A steering motor driven by operation of the steering wheel; A transmission means including a forward rotation part and a reverse rotation part which receive rotational force from the steering motor and generate rotational forces in opposite directions, respectively; Connecting means for selectively connecting any one of the forward rotation part and the reverse rotation part to the steering shaft in correspondence to an operation direction of the steering wheel; In the electronic power steering apparatus for a vehicle comprising a switching means for applying a drive signal to the steering motor at the time of operation of the steering wheel and at the same time the selective connection signal corresponding to the steering direction of the steering wheel to the connecting means. , The transmission means, A drive gear connected to the drive shaft of the steering motor and rotated; And a first driven gear interlocked with the drive gear and a first driven gear capable of rotating the steering gear in a forward direction when engaged with the steering gear integrated with the steering shaft while being integrally rotated with the first main gear. Forward rotation part, A reverse rotation part including a second main gear interlocked with the first main gear and a second driven gear capable of rotating the steering gear in a reverse direction while integrally rotating with the second main gear; A gear housing accommodating the forward rotation part and the reverse rotation part and hinged to an outer case to be detachably coupled to the steering gear to be rotated within a predetermined angle range; Each side of the gear housing is connected to a rod, and at the same time as the operation of the steering wheel receives a current corresponding to the steering direction of the steering wheel from the switching means to selectively rotate the gear housing by the electromagnetic force by this current. And at least two electromagnet assemblies for connecting either the first driven gear of the forward rotation part or the second driven gear of the reverse rotation part to the steering gear. The method according to claim 7, And an elastic means for restoring the forward or reverse rotated gear housing when no current is applied to the electromagnet assembly of the gear housing.