Universal joint

Abstract

The present invention relates to a universal joint configured to reduce steering friction by reducing bending torque of a yoke. The universal joint includes a body portion formed at one end of a yoke to engage a shaft to the body portion, a wing portion formed at one end of the yoke to engage the shaft to the body portion, and a rigidity weakening portion formed at the other end of the yoke. A wing portion formed at the other end of the yoke to press the bearing into the wing portion; the rigidity weakening portion is formed in a shape of a reduced cross-sectional area in a portion extending from the body portion to the wing portion.

Description

Technical Field

[0001] The present invention provides a universal joint configured to reduce steering friction by reducing the bending torque of a yoke. Background Art

[0002] like Figure 1 As shown, in the case of a rack-mounted motor-driven power steering system (R-MDPS), the torque sensor 2 is installed below the universal joint 1 .

[0003] Accordingly, the auxiliary force of the MDPS motor 3 does not take into account the friction of the universal joint 1 , so when the MDPS is in the powered state, the friction of the universal joint is directly transmitted to the driver.

[0004] On the other hand, the friction force of the universal joint installed in the vehicle is affected by the bending torque of the universal joint.

[0005] In other words, the friction of the universal joint increases as the bending torque increases.

[0006] For example, Figure 2 As shown, when a bolt (not shown) is fastened to a tab 7 formed in a hollow shape of the yoke 4 to engage the yoke 4 and the shaft 8 together, the yoke 4 is deformed as a whole as the gap in the slit 5 is reduced.

[0007] When the yoke 4 is deformed, the bending torque increases, stress is formed in the hollow portion 6, and the hollow portion away from the yoke and into which the bearing is pressed is deformed. Therefore, the pressure in the bearing increases compared to before the bolt is tightened, and the bending torque increases.

[0008] When the pressure in the bearing increases in this manner, this causes an increase in the magnitude of the vertical load (N) in the universal joint rotational friction (F=μ×N), thereby causing a problem of increased friction in the universal joint.

[0009] The matters described above as background technology are intended to provide a better understanding of the background of the invention and should not be regarded as an admission that the invention belongs to the prior art already known to a person of ordinary skill in the art. Summary of the invention

[0010] The present invention has been made in an effort to solve the above-described problems, and an object of the present invention is to provide a universal joint configured to reduce bending steering friction by reducing the bending torque of a yoke.

[0011] According to an embodiment of the present invention, a universal joint includes: a body part, a wing part and a rigidity weakened part, wherein the body part is formed at one end of a yoke so that a shaft is coupled to the body part; the wing part is formed at the other end of the yoke so that a bearing is pressed into the wing part; the rigidity weakened part is formed in a part extending from the body part to the wing part and has a reduced cross-sectional area.

[0012] The rigidity weakened portion may be formed in a shape extending from the body portion to the wing portion and having a concave outer surface.

[0013] The radius of the concave shape of the concave outer surface may be in the range of 6 to 14 mm.

[0014] The concave shapes may be formed on the right and left sides of the wing portion, respectively.

[0015] The concave shape may be symmetrically formed on right and left sides of the wing portion.

[0016] The slit may be formed in a radial direction of the shaft hole formed in the body portion, and the slit may be formed between the rigidity weakened portions.

[0017] A hollow portion-side end portion of the slit may be located at a minimum thickness portion of the rigidity weakened portion.

[0018] A minimum thickness portion of the rigidity weakened portion may be formed at a position a predetermined distance away from an edge of the hollow portion.

[0019] An inner diameter of the shaft hole may be in the range of 16 to 18 mm, and an outer diameter of a body portion forming the shaft hole may be in the range of 25 to 27 mm.

[0020] An intermediate yoke may be further included, the intermediate yoke being connected to the yoke through a spider having a bearing, and an intermediate shaft portion being integrally formed with a body portion of the intermediate yoke.

[0021] The intermediate shaft portion may have a solid shaft shape or a hollow shaft shape.

[0022] According to the present invention, when the bolt is fastened to the yoke, the stress that causes the yoke to deform is concentrated in the rigidity weakened portion, thereby preventing deformation in the hollow portion equipped with the bearing. Therefore, the present invention has the advantages of reducing the increase in the bending torque of the yoke, thereby reducing the friction of the universal joint and reducing the steering friction of the actual vehicle.

[0023] Further, the intermediate yoke and the intermediate shaft portion are integrally formed rather than welded together, thereby preventing an increase in friction before the bolts are tightened. Therefore, the present invention has the effect of reducing the overall friction of the universal joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram showing the installation position of the torque sensor in the R-MDPS structure.

[0025] Figure 2 FIG. 1 is a schematic diagram showing the shape of a conventional yoke.

[0026] Figure 3 Schematic diagram showing a universal joint applied to a steering device according to an embodiment of the present invention.

[0027] Figure 4 is a schematic diagram showing the shape of a yoke according to an embodiment of the present invention.

[0028] Figure 5 2 is a schematic diagram showing a concave shape of a rigidity weakened portion according to an embodiment of the present invention.

[0029] Figure 6 Schematic diagram showing an axial hole formed in a body portion according to an embodiment of the present invention.

[0030] Figure 7 is a schematic diagram showing another yoke integrally formed with an intermediate shaft portion according to an embodiment of the present invention.

[0031] Figure 8 Graph comparing fastening force and friction force analysis values ​​of a conventional universal joint and a universal joint according to the present invention.

[0032] Fig. 9 and Fig.10 Graph comparing friction force measurements as a function of steering angle for a conventional universal joint and a universal joint according to the invention.

[0033] Fig.11 For comparison Figure 7 Graph of friction force distribution for a universal joint with an integral yoke and a universal joint with a conventional welded yoke. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments disclosed in the present invention are described in detail with reference to the accompanying drawings, but the same reference numerals refer to similar or identical components regardless of the drawing numbers and repeated descriptions are omitted.

[0035] The suffixes “module” and “unit” of components used in the following description are given or used interchangeably only for convenience in writing of the specification, and do not necessarily have different meanings or functions by themselves.

[0036] When it is determined that the specific description of the related and known technology may obscure the essence of the embodiments disclosed herein, the specific description may be omitted. Further, it should be understood that the drawings are only intended to facilitate the understanding of the embodiments disclosed herein, and are not intended to limit the technical ideas disclosed herein to the drawings, and include all modified embodiments, equivalent embodiments or alternative embodiments within the spirit and technical scope of the present invention.

[0037] Terms including ordinal numbers (such as first, second, etc.) may be used to describe various components, but these components are not limited by these terms. These terms may be used only to distinguish one component from another component.

[0038] It should be understood that when a component is referred to as being "connected" or "joined" to another component, the component may be directly connected or joined to the other component, but other components may be interposed. On the contrary, it should be understood that when a component is referred to as being "directly connected" or "directly joined" to another component, there are no other components interposed therebetween.

[0039] Unless the context clearly indicates otherwise, singular expressions include plural expressions. When a component, device, element, etc. of the present invention is described as having a purpose or performing an operation, function, etc., the component, device or element should be considered herein as "configured to" meet the purpose or perform the operation or function.

[0040] In the present specification, terms such as “include” or “have” are intended to indicate the presence of implemented features, numbers, steps, operations, components, parts, or a combination thereof described in the specification, and should not be understood as excluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or a combination thereof.

[0041] A description of embodiments of the present invention follows with reference to the accompanying drawings.

[0042] According to an embodiment of the present invention, Figure 3 and Figure 4 As shown, the universal joint 10 includes a body portion 110, a wing portion 120 and a rigidity weakened portion 130, the body portion 110 is formed at one end of the yoke 100 so that the shaft 400 and the shaft 500 are coupled to the body portion 110; the wing portion 120 is formed at the other end of the yoke 100 so that the bearing 210 is pressed into the wing portion 120; the rigidity weakened portion 130 is formed in a shape of reduced cross-sectional area in a portion extending from the body portion 110 to the wing portion 120 to reduce rigidity.

[0043] like Figure 3 and Figure 4 As shown, the shaft 400 joined to the lower end on the steering column side is connected to the solid shaft 310a through the universal joint 10. The solid shaft 310a is assembled at the upper end of the intermediate shaft portion 310.

[0044] The shaft 500 joined to the upper end on the transmission side is connected to the hollow shaft 310b through the universal joint 10. The hollow shaft 310b is fitted at the lower end of the intermediate shaft portion 310.

[0045] In the universal joint 10 connected to the upper portion of the intermediate shaft portion 310 , the yoke 100 joined to the shaft 400 on the steering column side is rotatably connected to the intermediate yoke 300 joined to the upper end of the solid shaft 310 a through the cross shaft 200 .

[0046] In the universal joint 10 connected to the lower portion of the intermediate shaft portion 310 , the yoke 100 coupled to the shaft 500 on the transmission side is rotatably connected to the intermediate yoke 300 coupled to the lower end of the hollow shaft 310 b through the cross shaft 200 .

[0047] Therefore, the universal joint 10 is applicable to both the universal joint 10 connected to the steering column side and the universal joint 10 connected to the transmission side. For ease of understanding, the following description is based on the universal joint 10 connected to the steering column side.

[0048] The body portion 110 is formed at an upper end of the yoke 100 , and the wing portion 120 is formed in a left-right branched shape at a lower end of the yoke 100 in the body portion 110 .

[0049] A cylindrical shaft hole 111 is formed at the center of the body portion 110 in the axial direction so that the lower end of the shaft 400 on the steering column side is inserted into the shaft hole 111 .

[0050] The hollow portion 121 is formed in the shape of a circular hole at the ends of the two wing portions 120 so that the bearing 210 coupled to the cross shaft 200 is press-coupled to the hollow portion 121 .

[0051] In addition, a slit 112 having a predetermined gap in the outer diameter direction of the shaft hole 111 is formed along the shaft hole 111 until the portion extending to the hollow portion 121 .

[0052] A bolt hole is formed through the body portion 110 in a direction orthogonal to the gap in the slit 112 so that the bolt 113 is fastened to the bolt hole.

[0053] Accordingly, as the bolt 113 is tightened, the gap in the slit 112 is reduced, and the inner diameter of the shaft hole 111 is reduced. Therefore, the shaft 400, 500 can be firmly fastened in the shaft hole 111.

[0054] In the embodiment of the present invention, the rigidity weakened portion 130 is formed in the middle portion of the wing portion 120 extending from the body portion 110 to the hollow portion 121. The rigidity weakened portion 130 is formed in a shape of reduced cross-sectional area so that rigidity is reduced and the component is easily deformed in the event of deformation.

[0055] Accordingly, when the bolt 113 is tightened, even if the body portion 110 to which the bolt 113 is mounted is deformed, the stress causing the material in the rigidity weakened portion 130 to deform is concentrated in the rigidity weakened portion 130, thereby preventing the hollow portion 121 to which the bearing 210 is mounted from deforming. Accordingly, even when the bolt is tightened, the bearing can be smoothly operated, thereby reducing the amount of increase in the bending torque, and reducing the overall friction of the universal joint 10. Therefore, the steering friction of the actual vehicle is reduced.

[0056] In addition, if Figure 4 and Figure 5 As shown, according to the present invention, the rigidity weakened portion 130 may be formed in a shape extending from the body portion 110 to the wing portion 120 and having a concave outer surface.

[0057] In other words, the conventional yoke has Figure 2 The yoke shown has a straight outer surface extending from the main body portion 110 to the wing portion 120, while the yoke according to the present invention has a concave portion 130, which is formed into a concave shape in the middle of the outer surface extending from the main body portion 110 to the wing portion 120, so that the cross-sectional area of ​​the concave portion 130 is reduced.

[0058] By reducing the stress that causes the material of the hollow portion 121 to deform, the increase in the bending torque can be reduced.

[0059] In one embodiment, the radius R of the concave shape may be in the range of 6 to 14 mm.

[0060] In other words, the concave portion 130 is formed on the right and left outer surfaces of the wing portion 120 in a circular curved shape having a radius R of 6 to 14 mm.

[0061] When the radius R of the concave portion 130 is less than 6 mm, the concave portion 130 is not thick enough, resulting in lack of torsional strength and durability. If the radius R of the concave portion 130 is greater than 14 mm, the concave portion 130 is too thick, causing the hollow portion 121 to deform when the body portion 110 deforms.

[0062] In addition, concave shapes may be formed on the right and left sides of the wing portion 120 , respectively.

[0063] Further, the concave shapes may be symmetrically formed on the right and left sides of the wing portion 120 .

[0064] In other words, the concave portion 130 is formed in the same shape at the same position on the right and left sides of the wing portion 120, so that when the body portion 110 is deformed by the tightening of the bolt 113, the wing portion 120 is uniformly deformed on the right and left sides. Therefore, the stress is balanced, which means that the stress can be prevented from being inclined in one direction. This in turn helps to maintain rigidity and durability.

[0065] In another embodiment, Figure 5 As shown, the slits 112 may be formed in the radial direction of the shaft hole 111 formed in the body portion 110 , and the slits 112 may be formed between the rigidity weakened portions 130 .

[0066] For example, the slit 112 is formed between the right and left concave portions 130 .

[0067] In other words, when the bolt 113 is tightened, the gap in the slit 112 changes, and the body portion 110 is deformed.

[0068] Accordingly, since the gap in the slit 112 is reduced, the stress causing the deformation of the body portion 110 is concentrated in the concave portion 130 , thereby reducing the transfer of the stress causing the deformation of the body portion 110 to the hollow portion 121 .

[0069] In addition, the end portion of the slit 112 on the hollow portion 121 side is located at the minimum thickness portion of the rigidity weakened portion 130 (ie, the minimum thickness portion of the concave portion 130 ).

[0070] At this time, the straight line L connecting the most depressed parts of the concave portion 130 becomes the minimum thickness part, and the end of the slit 112 located closest to the hollow portion 121 becomes the end of the slit 112 on the hollow portion 121 side.

[0071] In other words, the end portion of the slit 112 on the hollow portion 121 side coincides with the straight line L which is the minimum thickness portion of the concave portion 130 , which helps to concentrate the stress causing the deformation of the body portion 110 in the concave portion 130 .

[0072] In addition, the minimum thickness portion of the rigidity weakened portion 130 may be formed at a position a predetermined distance from the edge of the hollow portion 121 .

[0073] In other words, the stress causing the body portion 110 to deform is concentrated in the concave portion 130 , and the concave portion 130 is formed at a predetermined distance from the hollow portion 121 , thereby more effectively reducing the transfer of the stress to the hollow portion 121 .

[0074] on the other hand, Figure 6 It is shown that the inner diameter D1 of the shaft hole 111 may be in the range of 16 to 18 mm, and the outer diameter D2 of the body portion 110 forming the shaft hole 111 may be in the range of 25 to 27 mm.

[0075] In one embodiment, when the inner diameter D1 of the shaft hole 111 is 17 mm, the body portion 110 may be formed to have an outer diameter D2 of 26 mm.

[0076] In other words, although the outer diameter D2 of the body portion 110 is set to 30 mm or more in the conventional yoke so that the body portion 110 is thick, the diameter D2 of the body portion 110 is reduced according to the present invention.

[0077] Therefore, the thickness of the body portion 110 is reduced by the same amount as the outer diameter D2 of the body portion 110 is reduced, thereby enhancing the tightening force of the shafts 400 and 500 when the bolts 113 are tightened. In addition, the rigidity of the portion where the body portion 110 is tightened is reduced, so that the deformation in the hollow portion 121 where the bearing is located is also relatively reduced.

[0078] In other words, Figure 8 As shown, in the yoke 100 of the present invention, the bending torque and friction force of the bearing 210 squeezed from the side where the bolt 113 is fastened are significantly reduced compared to the conventional yoke.

[0079] Accordingly, the sum of the friction forces in the bearings 210 on both sides is reduced by about 68%, thereby significantly reducing the steering friction force of the actual vehicle.

[0080] Furthermore, if Fig. 9 and Fig.10 As shown, the test results applied to a plurality of vehicles confirm that, compared with the conventional universal joint, the present invention significantly reduces the friction force caused by the steering angle change.

[0081] Accordingly, the overall steering feel is significantly improved, and not only is the steering feel such as the return feel clearer and enhanced, but the driver also better perceives road feedback and texture, resulting in improved on-center accuracy, faster response, and smoother return feel.

[0082] In one embodiment, if Figure 3 and Figure 7As shown, the intermediate yoke 300 is connected to the yoke 100 via a cross shaft 200 (which has a bearing 210 ), and an intermediate shaft portion 310 is integrally formed with a body portion 302 of the intermediate yoke 300 .

[0083] The intermediate shaft portion 310 may have a solid shaft 310a shape or a hollow shaft 310b shape.

[0084] In other words, the middle yoke 300 connected to the upper yoke 100 may be integrally formed with the middle shaft portion 310 having a solid shaft 310a shape, and the middle yoke 300 connected to the lower yoke 100 may be integrally formed with the middle shaft portion 310 having a hollow shaft 310b shape.

[0085] More specifically, the friction force is generally determined by the size of the hollow portion 121 formed in the yoke. In other words, when the size of the hollow portion 121 increases, the press-in force decreases and the friction force decreases.

[0086] However, if the size of the hollow portion 121 is too large, the steering feeling may be deteriorated or noise may be generated due to an increase in the gap between components.

[0087] Specifically, when the yoke is welded to the shaft, if thermal deformation occurs in the hollow portion 121 , the roundness of the hollow portion 121 may be affected, thereby causing an undesirable increase in friction.

[0088] Therefore, according to the present invention, the intermediate yoke 300 and the intermediate shaft portion 310 are integrally formed instead of being welded together, thereby preventing an increase in frictional force before tightening the bolt 113. Therefore, the overall frictional force in the universal joint 10 is reduced.

[0089] Fig.11 A graph showing friction force distribution for comparing a conventional welded yoke in which the intermediate yoke 300 and the intermediate shaft portion 310 are welded together and an integral yoke in which the intermediate yoke 300 and the intermediate shaft portion 310 are integrally formed.

[0090] As shown in the graph, it can be seen that, unlike the welded intermediate yoke, the integral intermediate yoke 300 does not have thermal deformation of the yoke occurring during the welding process, thereby reducing the average value and distribution of the bending torque.

[0091] As described above, according to the present invention, when the bolt 113 is fastened to the yoke 100, even if the body portion 110 equipped with the bolt 113 is deformed, the stress causing the deformation is concentrated in the rigidity weakened portion 130, thereby substantially reducing or preventing the deformation of the hollow portion 121 equipped with the bearing 210. Therefore, the increase in the bending torque is reduced, and the friction force in the universal joint 10 is reduced. Therefore, the steering friction force of the actual vehicle is reduced.

[0092] Further, the intermediate yoke 300 and the intermediate shaft portion 310 are integrally formed rather than welded together, thereby preventing the friction force from increasing before the bolts 113 are tightened. Therefore, the overall friction force in the universal joint is reduced.

[0093] Only specific embodiments of the present invention have been described in detail, but it is obvious to those skilled in the art that various improved embodiments and modified embodiments are possible within the scope of the technical spirit of the present invention, and such improved embodiments and modified embodiments should fall within the scope of the appended claims.

Claims

1. A universal joint, comprising: a body portion formed at a first end of the yoke so that the shaft is coupled to the body portion; a wing portion formed at the second end of the yoke so that the bearing is pressed into the wing portion; as well as A rigidity weakened portion is formed in a portion extending from the body portion to the wing portion and has a reduced cross-sectional area.

2. The universal joint according to claim 1, wherein: The rigidity weakened portion is formed in a shape extending from the body portion to the wing portion and having a concave outer surface.

3. The universal joint according to claim 2, wherein: The radius of the concave shape of the concave outer surface is in the range of 6 to 14 mm.

4. The universal joint according to claim 2, wherein: The concave shapes of the concave outer surface are respectively formed on the right and left sides of the wing portion.

5. The universal joint according to claim 2, wherein: The concave shape of the concave outer surface is symmetrically formed on the right and left sides of the wing portion.

6. The universal joint according to claim 1, wherein: A slit is formed in a radial direction of a shaft hole formed in the body portion, and the slit is formed between rigidity weakened portions.

7. The universal joint according to claim 6, wherein: The hollow portion side end portion of the slit is located at a minimum thickness portion of the rigidity weakened portion.

8. The universal joint according to claim 7, wherein: The minimum thickness portion of the rigidity weakened portion is formed at a position a predetermined distance away from an edge of the hollow portion.

9. The universal joint according to claim 6, wherein: The inner diameter of the shaft hole is in the range of 16 to 18 mm, and the outer diameter of the body portion forming the shaft hole is in the range of 25 to 27 mm.

10. The universal joint according to claim 1, further comprising: an intermediate yoke connected to the yoke by a cross shaft having a bearing; as well as An intermediate shaft portion is integrally formed with the body portion of the intermediate yoke.

11. The universal joint according to claim 10, wherein: The intermediate shaft portion has a solid shaft shape or a hollow shaft shape.

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