KR20170082925A - Electronic power steering using planetary gear - Google Patents

Abstract

A power steering apparatus using a planetary gear for transmitting power from an input shaft to an output shaft includes a sun gear connected to the input shaft, a plurality of planetary gears gear-connected to the sun gear, A ring gear connected to the planetary gear and a ring gear and a carrier connected to the output shaft at a central portion thereof and radially connected to the periphery of the output shaft at one side thereof and formed of a flexible material.

Description

[0001] ELECTRONIC POWER STEERING USING PLANETARY GEAR [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric steering apparatus using a planetary gear, and more particularly, to an electric steering apparatus using a planetary gear that can be meshed with a planetary gear and a ring gear, .

Generally, the speed reducer is provided for reducing the rotational speed of a high load transmitted through the driving shafts of a power source such as an electric motor, a servo motor, etc. mounted on an automobile, an elevator, a robot or the like.

The gears used in such speed reducers include spur gears, worm gears, and planetary gears. Reducers using worm gears and planetary gears use high-speed rotation output from an engine or a motor as input values, And decelerates and outputs a predetermined ratio so as to realize the stability and precision required by the control device.

In particular, a planetary gear reducer, which is a speed reducer using a planetary gear, is a type of transmission for decelerating and outputting a rotational force transmitted by a driving device such as an external motor at a predetermined ratio and distributing the rotational force to several planetary gears, It is applied to various parts such as heavy equipment and ship. The planetary gear reducer has the advantage of being able to compact and lightweight the gear box, to have high efficiency of power transmission, and to withstand high torque because the power is evenly distributed.

Such a planetary gear reducer can be applied to a rack-and-pinion steering system of an automobile, and decelerates the rotational power supplied to the input shaft and transmits the rotational power to the output shaft. At this time, a pinion is formed at the end of the output shaft, and the rotational motion of the pinion is converted into a rectilinear motion of the rack, thereby steering the vehicle.

As described above, in the case of a rack and pinion steering system, the final output shaft of the planetary speed reducer has a structure that transmits force to the pinion. The operation of the rotating parts with a high degree of concentricity is advantageous in noise and vibration of the product.

However, as shown in FIG. 1, in the steering process, the pinion 2 receives a lateral load due to the load of the rack 1, and as a result, the pinion shaft 3 in the shape of a long round bar is deformed. The amount of analysis is up to 30 μm. In particular, the deformation of the torque transmitting portion T adversely affects the assembly verticalness of the final output part of the reducer.

2, the planetary gear 5 and the ring gear 6 are engaged with each other, as shown in Fig. 2, so that the rotation of the pinion shaft 3 A problem will arise.

That is, in the planetary reduction gear in which the rotational motion of the rotation and revolution is mainly made, problems such as noise due to eccentricity or misalignment of the planetary gear 5 and the ring gear 6, There is a need for remedial measures.

Korean Patent Publication No. 10-2015-0027671

An electric steering apparatus using a planetary gear according to an embodiment of the present invention aims at solving the above-mentioned problems.

The planetary gears and the output shaft are formed of a flexible material so that even if the output shaft is deformed, the carrier can be deformed by its own elasticity and the planetary gear can be maintained in a state of being meshed with the ring gear in the normal range, And to provide a steering apparatus.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an apparatus and method for controlling the same.

An electric power steering apparatus using a planetary gear according to an embodiment of the present invention is for transmitting the power provided to an input shaft to an output shaft and includes a sun gear connected to the input shaft, a plurality of planetary gears gear- A ring gear that is in gear-contact with the planetary gear, and a carrier, which is connected to the output shaft at a central portion and is radially connected to the periphery of the output shaft at one side thereof.

The carrier includes a body formed in the shape of a disk, a hollow formed in the center of the body, the hollow being press-fitted into the output shaft, a plurality of connection holes formed radially around the hollow, And a bush formed integrally with the hollow and the connecting hole.

The carrier may be manufactured by an insert injection molding method.

The carrier may be formed of any one material selected from metal, rubber, silicone, polyurethane, glass fiber, and Teflon, or a mixture of two or more materials.

In the electric power steering apparatus using the planetary gear according to an embodiment of the present invention, the planetary gear and the carrier to which the output shaft is fixed are formed of a flexible material, so that even if the output shaft is deformed, So that the planetary gear can be maintained in the engaged state with the ring gear within the normal range.

In addition, it is possible to prevent noise and gear teeth from being worn out due to shifting of the planetary gears and the ring gear, and it is possible to reduce the intertia due to weight reduction of the parts, thereby improving the reverse steering noise.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a perspective view showing a rack-and-pinion steering system applied to a conventional automobile.
2 is a conceptual diagram showing a state in which the planetary gear and the ring gear are shifted from each other as the output shaft of the conventional speed reducer is deformed.
3 is a perspective view of an electric power steering apparatus using a planetary gear according to an embodiment of the present invention.
4 is a cross-sectional view of an electric steering system using a planetary gear according to an embodiment of the present invention.
5 is an exploded perspective view of an electric power steering apparatus using a planetary gear according to an embodiment of the present invention.
6 is an exploded perspective view showing the planetary gear and the carrier of FIG. 5 extracted.
7 is a conceptual diagram showing a state where the planetary gear and the ring gear are normally engaged even if the output shaft is deformed by the application of the present invention.
8 is a view showing a state in which an electric type steering apparatus using a planetary gear according to an embodiment of the present invention is applied to a steering apparatus of an automobile.
9 is a partially cutaway bottom perspective view of an electric power steering apparatus using a planetary gear according to another embodiment of the present invention.
10 is a sectional view of an electric steering system using a planetary gear according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

FIG. 3 is a perspective view of an electric power steering system using a planetary gear according to an embodiment of the present invention, and FIG. 4 is a sectional view of an electric steering system using a planetary gear according to an embodiment of the present invention.

3 to 4, an electric steering system using a planetary gear according to an embodiment of the present invention includes a sun gear 110, a planetary gear 120, a ring gear 130, and a flexible material And a carrier 140.

Generally, an electric type steering apparatus using a planetary gear includes a sun gear 110 formed on an input shaft 101 connected to a power source and receiving a rotational force, a ring gear 130 fixed to the inside of the housing 160, a sun gear 110 A plurality of planetary gears 120 rotating in engagement with the sun gear 110 and the ring gear 130 and the plurality of planetary gears 120 are fixed radially between the ring gear 130 and the ring gear 130, And a carrier (102) fixed thereto. The power source and the input shaft 101 may have a hollow shape and the output shaft 102 may be disposed to penetrate the hollow space of the input shaft 101 and the power source.

The electric steering apparatus having the above structure can be used as a speed reducer mounted on the steering system. The deceleration process using the electric steering system of the embodiment will be described step by step.

First, when a driving force is provided from a power source such as a motor through the input shaft 101, the sun gear 110 connected to the input shaft 101 rotates. A plurality of planetary gears 120 circumscribed to the sun gear 110 are engaged and rotated while the sun gear 110 rotates and the planetary gears 120 are supported by a ring gear 130 fixed to the inside of the housing 160 And revolves around the sun gear 110 at the same time. The carrier 140 is also rotated at the revolution speed of the planetary gear 120 by the planetary gear 120 because the planetary gear 120 is connected through the carrier 140 in a single module. At this time, the rotational speed of the carrier 140 is in a state of decelerating from the input shaft 101. Finally, the output shaft 102 fixed to the carrier 140 is rotated at a reduced speed together with the carrier 140.

The output shaft 102 may be bent or deformed when a load is applied to the output shaft 102. The carrier 140 and the planetary gear 120 connected to the output shaft 102 may also be affected by the setting, It is difficult to maintain the initial engagement state. When the angles of the carrier 140 and the planetary gear 120 are changed as described above, an error occurs in engagement between the planetary gear 120 and the ring gear 130, and noise and gear teeth wear, of course , The power transmission can not proceed smoothly.

In particular, when the electric steering system of the present invention is applied to a speed reducer of a steering system, an output shaft 102 having a pinion formed due to a load of a rack receives a lateral load and is deformed. Noise is generated while the gear 120 is shifted from the ring gear 130 fixed to the housing 160, and there is a problem in gear engagement, which causes a problem that the steering precision is lowered. In order to solve such a problem, conventionally, a method of adding a bearing or adding flesh to an assembly part has been adopted.

However, in the case of the present invention, the carrier 140 connecting the planetary gear 120 and the output shaft 102 is formed of a flexible material, without additional parts for solving such a problem.

Here, the flexible material means a variety of known materials having a predetermined strength and deformed when an external force is applied thereto, and the carrier 140 may be made of a material having elasticity according to circumstances.

FIG. 7 is a conceptual view showing a state in which the planetary gear and the ring gear are normally engaged even if the output shaft is deformed by the application of the present invention, and FIG. 8 is a schematic view showing a state in which the electric steering apparatus using the planetary gear according to the embodiment of the present invention Fig.

8, a pinion 103 is formed at the end of the output shaft 102. When the pinion 103 is engaged with the rack 104, a lateral load is applied to the pinion 103 due to the load of the rack 104, (102) is deformed.

However, in the present invention, since the carrier 140 is formed of a flexible material, as shown in FIG. 7, the carrier 140 itself deforms to compensate for the deformation of the output shaft 102, 120). Therefore, the planetary gear 120 and the ring gear 130 do not shift out of the normal range of the rotation axis, and the planetary gear 120 and the ring gear 130 can be maintained in the engaged state in the normal range.

FIG. 5 is an exploded perspective view of an electric power steering apparatus using a planetary gear according to an embodiment of the present invention, and FIG. 6 is an exploded perspective view illustrating the planetary gear and the carrier of FIG.

5 to 6, the carrier 140 has a body 141 formed in the form of a disk and a hollow 142 formed in the center of the body 141 and into which the output shaft 102 is inserted And a plurality of connection holes 143 radially disposed on the body 141 around the hollow 142 and perforated to connect the planetary gear 120.

For example, a planetary pin 121 is connected to the center of the planetary gear 120 through a means such as a needle bearing so as to idle. The end of the planetary pin 121 is press-fitted into the connection hole 143 of the carrier 140 and the output shaft 102 is also press-fitted into the hollow 142 of the carrier 140. Thus, the planetary gear 120 revolves so that the carrier 140 rotates, and the output shaft 102 can rotate while the carrier 140 rotates.

As another example, a serration can be machined to increase the power transferring force between the coupling pin 143 of the planetary fin 121 and the carrier 140, and the hollow 142 of the output shaft 102 and the carrier 140.

Also, in this embodiment, the bushes 150 are integrally formed with the hollow 142 and the connection hole 143 of the carrier 140. The bush 150 is disposed between the hollow 142 and the output shaft 102 of the carrier 140 and between the connecting hole 143 of the carrier 140 and the planetary pin 121 to prevent slip and increase the mutual coupling force .

The carrier 140 may be provided with protrusions 145 that are axially protruded along the peripheries of the body 141 or along the peripheries of the hollow 142 and the connection 143 to increase the thickness of the protrusions 145, 140 may have a relatively concave base at an area where the protrusion 145 is not formed. The strength of the hollow 142, the coupling 143, and the body 142 can be improved by the configuration of the projection 145 as described above.

Alternatively, the carrier 140 may have various shapes such as a triangle, a square, and the like having a predetermined thickness as well as a shape of a disk.

In this embodiment, the carrier 140 may be manufactured by an insert injection molding method.

As described above, the bushes 150 are integrally formed in the hollow 142 and the coupling 143 of the carrier 140. Therefore, an insert injection molding method is used to integrally process the bush 150 made of a metal and the carrier 140 made of a non-metal material. When the insert injection molding method is adopted for coupling the carrier 140 and the bush 150, the bond strength between the bush 150 made of a metal and the carrier 140 made of a non-metallic material can be secured, And, above all, there is an advantage of being easy to manufacture.

In this embodiment, the carrier 140 may be formed of any one material selected from metal, rubber, silicon, polyurethane, glass fiber, and Teflon or a mixture of at least two materials. However, the scope of the present invention is not limited thereto, and various materials can be applied to manufacture the carrier 140 in a range having flexibility and elasticity.

FIG. 9 is a partially cutaway bottom perspective view of an electric power steering apparatus using a planetary gear according to another embodiment of the present invention, and FIG. 10 is a sectional view of an electric power steering apparatus using a planetary gear according to another embodiment of the present invention.

9 to 10, an electric power steering apparatus using a planetary gear according to another embodiment of the present invention is for transmitting the power provided to the input shaft 101 to the output shaft 102 and is connected to the input shaft 101 A plurality of first planetary gears 120a which are circumscribed and connected to the first sun gear 110a and a plurality of first planetary gears 120a which are in gear contact with the first planetary gears 120a, A first carrier 140a connected to an auxiliary output shaft 111b at a central portion and radially connected to the first planetary gear 120a at a periphery of an auxiliary output shaft 111b at one side thereof, A plurality of second planetary gears 120b that are circumscribed and connected to the second sun gear 110b and a plurality of second planetary gears 120b that are gear- 2 ring gear 130b and an output shaft 102 connected to a center portion of the ring gear 130b, Control (120b) is connected radially, and a second carrier (140b) made of a flexible material.

The electric steering apparatus having the above structure can be utilized as a two-stage speed reducer of an automotive steering system. For the sake of understanding, the two-stage deceleration process using the electric-powered steering apparatus of the above-described embodiment will be described step by step.

First, when a driving force is provided from a power source such as a motor through the input shaft 101, the first sun gear 110a connected to the input shaft 101 rotates. The first sun gear 110a is rotated and a plurality of first planetary gears 120a circumscribed to the first sun gear 110a are engaged and rotated and the first planetary gear 120a is fixed to the inside of the housing 160 Is supported by the first ring gear (130a) and revolves around the first sun gear (110a) while rotating. Since the first planetary gear 120a is connected to the first carrier 140a in one module, the first carrier 140a is also rotated by the first planetary gear 120a, Speed. At this time, the rotation speed of the first carrier 140a is in a state where the first deceleration is performed from the input shaft 101. [

The auxiliary output shaft 110b and the second sun gear 110b connected to the first carrier 140a are rotated at the same speed as that of the first carrier 140a when the first carrier 140a is rotated for the first deceleration, The second sun gear 110b rotates and the second planetary gear 120b engaged with the second sun gear 110b rotates. The second planetary gear 120b is supported on the second ring gear 130b fixed in the housing 160 and rotates while revolving around the second sun gear 110b. The second carrier 140b is rotated by the idle rotation of the second planetary gear 120b by the second planetary gear 120b because the second planetary gear 120b is connected to the second carrier 140b in a single module, Speed. At this time, the rotation speed of the second carrier 140b is in a state where the second deceleration is performed from the input shaft 101. [

Finally, the output shaft 102 fixed to the second carrier 140b is rotated at a second decelerated speed together with the second carrier 140b.

In this rotation process, when a load is applied to the output shaft 102, the output shaft 102 is bent or deformed, and the second carrier 140b and the second planetary gear 120b, which are connected to the output shaft 102, It is difficult to maintain the angle. As described above, when the angle of the second carrier 140b and the second planetary gear 120b is changed, an error occurs in engagement with the second ring gear 130b engaged with the second planetary gear 120b, Wear of the gear teeth occurs, and power transmission can not proceed smoothly.

In particular, when applied to a speed reducer of a steering system, a rack load is applied to the pinion 103 formed on the output shaft 102, and the output shaft 102 receives a lateral load and is deformed. Due to the influence of the output shaft 102, The second planetary gear 120b and the second ring gear 130b fixed to the housing 160 generate noise while shifting the rotational axis, and there arises a problem in engagement of the gears, which causes a problem that steering accuracy is deteriorated.

In the present invention, the second carrier 140b connecting the second planetary gear 120b and the output shaft 102 is formed of a flexible material in order to improve such a phenomenon. Here, the flexible material means a variety of known materials having a predetermined strength and deformed when an external force is applied thereto, and may include a material having elasticity as required.

As described above, when the second carrier 140b is formed of a flexible material, the second carrier 140b itself deforms to compensate for the deformation of the output shaft 102, so that the second planetary gear 120b The effect is not affected. Therefore, since the rotational axes of the second planetary gear 120b and the second ring gear 130b are not shifted out of the normal range, the state in which the second planetary gear 120b and the second ring gear 130b are meshed within the normal range .

5 to 6, the second carrier 140b includes a body formed in the shape of a disk, a hollow formed in the center of the body and having an output shaft inserted therein, And a plurality of connection ports radially disposed on the body and configured to connect the planetary gears with planetary pins that are idly connected to the planetary gears.

The bush 150 may be integrally formed with the hollow and the connecting hole of the second carrier 140b. The bush 150 is disposed between the hollow of the second carrier 140b and the connecting pin of the output shaft 102 and the second carrier 140b and the planetary pin. As the bushing 150 is formed, it is possible to prevent a slip occurring between the hollow of the second carrier 140b and the connecting pin of the output shaft 102 and the second carrier 140b and the planetary pin, and the mutual coupling force can be increased.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.

101: input shaft
102: Output shaft
103: Pinion
110: sunfish
120: planetary gear
121: connection axis
130: ring gear
140: Carrier
141: Body
142: hollow
143: Connector
145:
160: Housing

Claims (4)

An electric steering apparatus for transmitting power provided as an input shaft to an output shaft,
A sun gear connected to the input shaft;
A plurality of planetary gears circumscribed by said sun gear;
A ring gear that is in gear-contact with the planetary gear; And
And a carrier which is connected to the output shaft at a central portion and is radially connected to the periphery of the output shaft on one side thereof and is made of a flexible material. The method according to claim 1,
The carrier comprises:
A body in the form of a disc;
A hollow formed at the center of the body, into which the output shaft is inserted;
A plurality of connection holes formed radially around the hollow and connected to the planetary gears;
And a bush integrally connected to the hollow and the coupling hole. 3. The method of claim 2,
Wherein the carrier is manufactured by an insert injection molding method. The method according to claim 1,
Wherein the carrier is formed by mixing any one material selected from the group consisting of metal, rubber, silicone, polyurethane, glass fiber, and Teflon or a mixture of two or more materials.

Images