Electric motor-driven power steering system for a vehicle

Abstract

This disclosure relates to an electric motor-driven power steering system for a vehicle, configured to prevent worm movement and backlash caused by tooth clearance between the worm wheel and the worm by using a bearing-integrated damper bushing made of steel and coupled to the end of the worm. During worm rotation, lubricant is supplied between the worm and the bearing-integrated damper bushing to promote lubrication and cooling.

Description

Technical Field

[0001] This invention relates to an electric motor-driven power steering system for a vehicle, and more specifically, to a technique relating to an electric motor-driven power steering system for a vehicle, wherein an integral bearing damper bushing coupled to the end of a worm gear can be used to prevent worm movement and to prevent backlash caused by backlash between the worm wheel and the worm. Background Technology

[0002] Generally speaking, an electric motor-driven power steering system refers to a device in which an electronic control unit drives the drive components based on the vehicle's driving conditions detected by speed sensors, steering torque sensors, etc., to assist the driver in steering.

[0003] Normally, it provides a light and comfortable steering feel when the vehicle is traveling at low speeds, and a heavy and stable steering feel when the vehicle is traveling at high speeds. In emergency situations, it allows for quick steering, which helps improve driving safety.

[0004] The electric motor-driven power steering system includes: a drive (motor); a worm gear connected to and rotating with the drive; and a turbine gear meshing with and rotating with the worm gear, with a steering shaft passing through and connected to the center of the worm gear.

[0005] Therefore, the rotational force of the worm gear generated by the motor is added to the rotational force of the steering wheel operated by the driver and transmitted to the steering shaft, improving the steering feel and achieving stable steering.

[0006] The coupling-side bearing is connected to one end of the worm gear connected to the motor side, thereby allowing the worm gear to tilt to prevent jamming between the worm wheel and the worm gear teeth during vehicle operation.

[0007] The worm bearing is connected to the other end of the worm to prevent worm movement and to prevent backlash caused by the tooth clearance between the worm wheel and the worm. Furthermore, a shock-absorbing spring assembly (spring plate, spring, and push rod) for applying pressure and supporting the worm bearing in the circumferential direction, a worm bushing for supporting the worm in the axial direction, and a plug are mounted on it.

[0008] However, the problem with worm bearings, anti-vibration spring assemblies (spring plates, springs, and push rods), worm bushings, plugs, etc., used to prevent worm movement and backlash, is that the large number of complex and heavy components increases manufacturing costs.

[0009] Worm bearings that use ball bearings are prone to generating noise.

[0010] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or suggestion of any kind that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0011] Various aspects of the present invention aim to provide an electric motor-driven power steering system for vehicles, wherein an integral bearing damper bushing coupled to the end of a worm gear prevents movement of the worm gear and prevents backlash caused by the tooth gap between the worm wheel and the worm gear. This allows multiple conventionally used components, such as worm bearings, damping spring assemblies (leaf springs, springs, and pushrods), worm bushings, and plugs, to be combined into a single integral bearing damper bushing, thereby simplifying the structure, reducing weight, saving costs, and minimizing noise.

[0012] According to various exemplary embodiments of the present invention, an electric motor-driven power steering system for a vehicle includes: a worm gear that meshes with a worm wheel coupled to a steering shaft, is housed within a housing, and is rotated by power received from an electric motor; and a bearing-integrated damper bushing fitted onto the outer circumferential surface of the end of the worm gear and supported by the housing to prevent movement of the worm gear and backlash caused by the tooth backlash between the worm wheel and the worm gear.

[0013] The housing contains a lubricant collection section filled with lubricant, and the end of the worm gear, together with the bearing-integrated damping bushing, is immersed in the lubricant.

[0014] Due to the weight of the lubricant, the inside of the lubricant collection section is always filled with lubricant.

[0015] A hollow groove is recessed at the end of the worm, and multiple lubricant discharge holes are formed to connect the hollow groove fluid to the outer peripheral surface of the end of the worm. An integrated bearing damper bushing is fitted onto the end of the worm, such that the inner peripheral surface of the integrated bearing damper bushing faces the multiple lubricant discharge holes.

[0016] Multiple shaft protrusions are formed on the inner circumferential surface of the hollow groove, and the multiple shaft protrusions protrude into the interior of the hollow groove. When the worm rotates, the multiple shaft protrusions cause the lubricant to rotate, so as to allow the lubricant to be introduced into the multiple lubricant discharge holes.

[0017] As the worm rotates, the lubricant present in the hollow groove is introduced into the inner circumferential surface of the bearing integrated damper bushing through multiple lubricant discharge holes by centrifugal force, promoting lubrication and cooling between the worm and the bearing integrated damper bushing.

[0018] The bearing-integrated damper bushing is made of steel, formed into an annular shape with a predetermined cross-sectional thickness and width, and is configured to be mounted on the outer circumferential surface of the worm and supported by the housing.

[0019] The inner circumferential surface of the integrated bearing damper bushing is coated with Teflon, and therefore the integrated bearing damper bushing acts as a bearing during worm rotation.

[0020] The bearing-integrated damper bushing includes multiple outwardly projecting support protrusions, which are supported by a housing to prevent movement of the worm and clearance caused by the tooth backlash between the worm wheel and the worm.

[0021] The support protrusion is formed by stamping and cutting a portion of the bearing integrated damper bushing, and then making the cut portion protrude outward to form an integral part with the bearing integrated damper bushing.

[0022] The plurality of support protrusions include: a right support protrusion configured to apply a support force relative to the housing when the steering wheel is rotated clockwise to turn the vehicle to the right; and a left support protrusion configured to apply a support force relative to the housing when the steering wheel is rotated counterclockwise to turn the vehicle to the left. The right and left support protrusions are arranged symmetrically with respect to the center of the bearing-integrated damper bushing.

[0023] The plurality of support protrusions include: a right support protrusion, configured to be spaced apart from the right support protrusion in a clockwise direction and to bear loads on the right side; and a left support protrusion, configured to be spaced apart from the left support protrusion in a counterclockwise direction and to bear loads on the left side. The right and left support protrusions are configured to be symmetrical about the center of the bearing-integrated damper bushing.

[0024] The advantages of the electric motor-driven power steering system for vehicles according to various exemplary embodiments of the present invention are that the bearing-integrated damper bushing, made of steel and connected to the end of the worm, prevents worm movement and prevents backlash caused by the tooth backlash between the worm wheel and the worm, thereby achieving structural simplification, weight reduction and cost savings by reducing the number of parts, and in particular, minimizing noise.

[0025] The methods and apparatus of the present invention have other features and advantages, which will become apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein and, together with the specific embodiments described herein, serve to explain certain principles of the invention. Attached Figure Description

[0026] Figure 1 A schematic configuration of an electric motor-driven power steering system for a vehicle according to various exemplary embodiments of the present invention is shown;

[0027] Figure 2 The diagram illustrates a state in which the worm gear and bearing integrated damper bushing are separated from each other, according to various exemplary embodiments of the present invention.

[0028] Figure 3 Hollow grooves, lubricant discharge holes, and shaft protrusions formed on a worm gear according to various exemplary embodiments of the present invention are shown.

[0029] Figure 4 This is a front view exemplarily illustrating the state in which the worm gear and bearing integrated damper bushing are connected to each other according to various exemplary embodiments of the present invention; and

[0030] Figure 5 and Figure 6 These are perspective and front views of an integral bearing damper bushing according to various exemplary embodiments of the present invention.

[0031] It is understood that the accompanying drawings are not necessarily drawn to scale and present slightly simplified representations of various features illustrating the basic principles of the invention. Specific design features of the invention as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and environment of use.

[0032] In the accompanying drawings, reference numerals throughout the drawings refer to parts that are the same as or equivalent to the present invention. Detailed Implementation

[0033] Reference will now be made in detail to various embodiments of the invention, examples of which are shown in the accompanying drawings and described below. Although the invention will be described in conjunction with exemplary embodiments thereof, it should be understood that this description is not intended to limit the invention to those exemplary embodiments. On the other hand, the invention is intended to cover not only the exemplary embodiments thereof, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention. The invention is as defined in the appended claims.

[0034] The specific structural or functional descriptions of embodiments of the invention included in the specification or application are provided only for describing exemplary embodiments of the invention according to various exemplary embodiments. Therefore, exemplary embodiments of the invention according to various exemplary embodiments can be implemented in various forms, and the invention should not be construed as limited to the exemplary embodiments described in the specification or application.

[0035] Various changes and modifications can be made to the exemplary embodiments of the present invention, and therefore various exemplary embodiments will be shown in the drawings and described in the specification or application. However, it should be understood that embodiments conceived in accordance with the present invention are not limited to the specifically disclosed exemplary embodiments, but rather that the present invention includes all modifications, equivalents, and substitutions falling within the spirit and scope of the present invention.

[0036] Terms such as “first” and / or “second” may be used to describe various elements, but these elements should not be limited by these terms. These terms are intended only to distinguish one element from others. For example, without departing from the scope of this invention, a first element may be named a second element, and similarly, a second element may be named a second element.

[0037] When an element is described as "connected" or "accessible" to other elements, it should be understood that not only is that element directly connected to or accesses other elements, but there can also be another element between them. Conversely, when a component is described as "directly connected" or "directly accessing" any other component, it should be understood that there is no component between them. Other expressions describing the relationship between structural elements, namely "between" and "only between" or "adjacent" and "directly adjacent," should be interpreted similarly to the descriptions above.

[0038] The terminology used in the various exemplary embodiments of this invention is for describing particular embodiments only and is not intended to limit the invention. Singular expressions may include plural expressions unless they are clearly different in the context. As used herein, the expressions “comprising” or “having” are intended to specify the presence of the mentioned features, quantities, steps, operations, elements, components or combinations thereof, and should be construed as not excluding the possibility of the presence or addition of one or more other features, quantities, steps, operations, elements, components or combinations thereof.

[0039] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the various exemplary embodiments of the invention pertain. Terms such as those defined in general dictionaries may be interpreted as having the same meaning as in the context of the relevant technical field and should not be interpreted as having an ideal or overly formal meaning unless explicitly defined in the various exemplary embodiments. This invention.

[0040] The control unit (controller) according to an exemplary embodiment of the present invention may be implemented via a non-volatile memory configured to store data about an algorithm configured to control the operation of various components of a vehicle or software instructions for reproducing the algorithm, and a processor configured to perform the operations described below by using data stored in the respective memory. The memory and processor may be implemented as separate chips. Alternatively, the memory and processor may be implemented as an integrated single chip. The processor may be in the form of one or more processors.

[0041] In the following description, an electric motor-driven power steering system for a vehicle according to various exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0042] like Figures 1 to 6As shown, an electric motor drive power steering (MDPS) system for a vehicle according to various exemplary embodiments of the present invention includes: a housing 100; a worm gear 200, which is housed within the housing 100 and integrally connected to a steering shaft 10 extending through the center of the worm gear 200; a worm 300, which is housed within the housing 100 and meshes with the worm gear 200 to rotate integrally with the worm gear 200; a coupling-side bearing 400, which is coupled to one end of the worm 300; a motor 500, which is connected to one end of the worm 300 extending through the coupling-side bearing 400 and provides power to rotate the worm 300 when driven under the control of a controller (ECU); and a bearing-integrated damper bushing 600, which is fitted on the outer peripheral surface of the other end of the worm 300 and supported by the housing 100 to prevent movement of the worm 300 and backlash caused by the worm gear 200 and the worm 300.

[0043] One end of the worm gear 300 is connected to the motor shaft 510 via a flexible coupling 700 to receive power from the motor 500.

[0044] The connector-side bearing 400 serves to restrict the movement of the worm 300 in its axial direction.

[0045] In addition, the coupling side bearing 400 also serves to allow the worm 300 to tilt, so as to prevent the teeth of the worm wheel 200 and the worm 300 from getting stuck.

[0046] That is, the coupling-side bearing 400 includes: an inner ring, press-fitted to the outer circumferential surface of one end of the worm gear 300; an outer ring, fixed to the housing 100; and a plurality of ball bearings inserted into the bearing grooves of the inner and outer rings, allowing the inner and outer rings to rotate relative to each other. The bearing grooves formed in the inner and outer rings are formed with an elliptical shape larger than that of the ball bearings, thus allowing the coupling-side bearing 400 to tilt.

[0047] According to various exemplary embodiments of the present invention, the housing 100 has a lubricant collection section 110 formed therein and having a predetermined space, and the lubricant collection section 110 is filled with lubricant 800 for lubrication and cooling.

[0048] In one example, grease is used as lubricant 800, and in order to lubricate and cool the bearing integrated damper bushing 600 by means of lubricant 800, the worm 300 is configured such that the other end of the worm 300 is inserted into the lubricant collection section 110 together with the bearing integrated damper bushing 600 and immersed in lubricant 800.

[0049] Due to the weight of the lubricant 800, the interior of the lubricant collection section 110 is always filled with lubricant 800. Therefore, a separate device for storing the lubricant 800 in the lubricant collection section 110 is not required, thus helping to reduce weight and cost.

[0050] A hollow groove 310 is formed in and recessed into the other end of the worm 300. A plurality of lubricant discharge holes 320, connecting the hollow groove 310 to the outer circumferential surface of the other end of the worm 300, are formed spaced apart from each other in the circumferential direction of the worm 300. A bearing-integrated damper bushing 600 is fitted onto the other end of the worm 300 such that the inner circumferential surface of the bearing-integrated damper bushing 600 faces the plurality of lubricant discharge holes 320.

[0051] When the other end of the worm 300, which is connected to the bearing integrated damper bushing 600, is inserted into the lubricant collection part 110 filled with lubricant 800, the lubricant 800 fills the hollow groove 310 of the worm 300.

[0052] Multiple shaft protrusions 330 are formed on the inner circumferential surface of the hollow groove 310 of the worm 300, and are spaced apart from each other in the circumferential direction while protruding into the hollow groove 310.

[0053] When the worm gear 300 rotates under the power of the motor 500, the multiple shaft protrusions 330 rotate and circulate the lubricant 800. At this time, the lubricant 800 is introduced into the multiple lubricant discharge holes 320 by the rotation or centrifugal force caused by the multiple shaft protrusions 330. Finally, the lubricant 800 is introduced into the inner circumferential surface of the bearing integrated damper bushing 600 through the multiple lubricant discharge holes 320, promoting lubrication and cooling between the worm gear 300 and the bearing integrated damper bushing 600.

[0054] According to various exemplary embodiments of the present invention, the bearing-integrated damper bushing 600 is made of steel, formed into an annulus having a predetermined cross-sectional thickness (tl) and width (Dl), and is configured to be mounted on the outer peripheral surface of the other end of the worm gear 300 and supported by the housing 100.

[0055] The inner circumferential surface of the bearing-integrated damper bushing 600 is coated with a Teflon coating 610 to reduce frictional interference with the worm 300. Due to the Teflon coating 610, the bearing-integrated damper bushing 600 acts as a bearing during the rotation of the worm 300.

[0056] The bearing-integrated damper bushing 600 includes a plurality of outwardly projecting support protrusions 620. The plurality of support protrusions 620 can be configured to be supported by the housing 100, thus preventing movement of the worm 300 and clearance caused by the backlash between the worm wheel 200 and the worm 300.

[0057] A plurality of support protrusions 620 formed on the bearing-integrated damper bushing 600 are formed by stamping a portion of the bearing-integrated damper bushing 600, and then the cut portion protrudes outward to be integrally formed with the bearing-integrated damper bushing 600. The plurality of support protrusions 620 include: a right support protrusion 621 configured to apply a support force to the housing 100 when the steering wheel is rotated clockwise to turn the vehicle to the right; a left support protrusion 622 configured to apply a support force to the housing 100 when the steering wheel is rotated counterclockwise to turn the vehicle to the left; a right support protrusion 623 configured to be spaced apart from the right support protrusion 621 in the clockwise direction and to bear right-side loads; and a left support protrusion 624 configured to be spaced apart from the left support protrusion 622 in the counterclockwise direction and to bear left-side loads.

[0058] The right support protrusion 621 and the left support protrusion 622 are configured to be symmetrical about the center of the bearing-integrated damper bushing 600. Furthermore, the right support protrusion 623 and the left support protrusion 624 are configured to be symmetrical about the center of the bearing-integrated damper bushing 600. Therefore, the advantage is that the bearing-integrated damper bushing 600 can apply a stable supporting force through contact with the housing 100, and because the multiple support protrusions 620 are configured to be symmetrical about the center, they can be used together as needed.

[0059] As described above, the electric motor-driven power steering system for a vehicle according to various exemplary embodiments of the present invention can use a bearing-integrated damper bushing 600, made of steel and coupled to the end of the worm 300, to prevent movement of the worm 300 and backlash caused by the tooth backlash between the worm wheel 200 and the worm wheel 300. Therefore, the electric motor-driven power steering system can have a simplified structure, reduced weight, and lower cost by reducing the number of components, and can minimize noise generation as much as possible.

[0060] Furthermore, various exemplary embodiments of the present invention are configured such that during the rotation of the worm 300, lubricant 800 is supplied between the worm 300 and the bearing integrated damper bushing 600 to promote lubrication and cooling between them, thereby reducing operating noise and improving durability.

[0061] For ease of interpretation and accurate definition of the appended claims, the terms “upper,” “lower,” “inner,” “outer,” “up,” “lower,” “upward,” “downward,” “front,” “back,” “behind,” “inside,” “outside,” “inward,” “outward,” “internal,” “external,” “inner,” “external,” “forward,” and “backward” are used to describe features of the exemplary embodiments with reference to the positions of these features shown in the figures. It will be further understood that the term “connection” or its derivatives refer to both direct and indirect connections.

[0062] The foregoing description of specific exemplary embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and it will be apparent that many modifications and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described to explain certain principles of the invention and its practical application, enabling others skilled in the art to implement and utilize various exemplary embodiments of the invention, as well as various alternatives and modifications thereof. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. An electric motor-driven power steering system for a vehicle, comprising: case; A worm gear, which meshes with a worm wheel connected to a steering shaft, is housed within a housing and rotates by power received from a motor; as well as An integrated bearing damper bushing, which is fitted onto the outer circumferential surface of the first end of the worm and supported by the housing, to prevent movement of the worm and clearance caused by the backlash between the worm wheel and the worm. The hollow groove is recessed into the first end of the worm gear. A plurality of lubricant discharge holes are formed on the first end of the worm gear to connect the hollow groove fluid to the outer peripheral surface of the first end of the worm gear, and The bearing-integrated damper bushing is fitted onto the first end of the worm gear, such that the inner circumferential surface of the bearing-integrated damper bushing faces the plurality of lubricant discharge holes.

2. The motor-driven power steering system according to claim 1, wherein, A lubricant collection section is formed in the housing. The lubricant collection section is filled with lubricant, and The first end of the worm gear, together with the bearing-integrated damper bushing, is configured to be immersed in the lubricant.

3. The motor-driven power steering system according to claim 2, wherein, Due to the weight of the lubricant, the interior of the lubricant collection section is always filled with the lubricant.

4. The electric motor-driven power steering system according to claim 1, wherein, Multiple shaft protrusions are formed on the inner circumferential surface of the hollow groove and protrude toward the interior of the hollow groove, and When the worm rotates, the plurality of shaft protrusions cause the lubricant to rotate so that the lubricant can be introduced into the plurality of lubricant discharge holes.

5. The electric motor-driven power steering system according to claim 1, wherein, When the worm rotates, the lubricant present in the hollow groove is introduced into the inner circumferential surface of the bearing integrated damper bushing through the plurality of lubricant discharge holes by centrifugal force, thereby promoting lubrication and cooling between the worm and the bearing integrated damper bushing.

6. The electric motor-driven power steering system according to claim 1, wherein, The bearing-integrated damper bushing is made of steel, formed into an annular shape with a predetermined cross-sectional thickness and width, and is configured to be mounted on the outer circumferential surface of the first end of the worm and supported by the housing.

7. The motor-driven power steering system according to claim 1, wherein, The inner circumferential surface of the integrated bearing damper bushing is coated with a Teflon coating, and therefore the integrated bearing damper bushing acts as a bearing during the rotation of the worm gear.

8. The electric motor-driven power steering system according to claim 1, wherein, The integrated bearing damper bushing includes multiple support protrusions protruding outward from the outer circumference of the integrated bearing damper bushing, and The plurality of support protrusions are supported by the housing to prevent movement of the worm and clearance caused by the tooth gap between the worm wheel and the worm.

9. The electric motor-driven power steering system according to claim 8, wherein, The support protrusion is formed by stamping a portion of the bearing integrated damper bushing and then making the cut portion protrude outward to form an integral part of the bearing integrated damper bushing.

10. The motor-driven power steering system according to claim 8, wherein, The plurality of support protrusions include: A right support protrusion configured to apply a support force to the housing when the steering wheel is rotated clockwise to turn the vehicle to the right; and A left support protrusion is configured to apply a supporting force to the housing when the steering wheel is rotated counterclockwise to turn the vehicle to the left. The right support protrusion and the left support protrusion are configured to be symmetrical about the center of the bearing integrated damper bushing.

11. The electric motor-driven power steering system according to claim 10, wherein, The plurality of support protrusions also include: A right-side support protrusion, configured to be spaced apart from the right support protrusion in a clockwise direction and to bear the load on the right side; and A left-side support protrusion is configured to be spaced apart from the left support protrusion in a counterclockwise direction and to bear the load on the left side. The right-side support protrusion and the left-side support protrusion are configured to be symmetrical about the center of the bearing integrated damper bushing.

12. The motor-driven power steering system according to claim 1, wherein, The second end of the worm gear is connected to the motor shaft of the motor via a flexible coupling.

Images