Anti-coming-off axial seal structure for electric power steering device of automobile

Abstract

The utility model discloses a kind of anti-drop axial sealing structures for automobile electric power steering device, including the sealing groove on the sealing groove of pair of hand tools and the sealing element installed in the sealing groove;The sealing groove is rectangular groove structure, and groove depth and groove width cooperation form the full week constraint of sealing element;The cross section of the sealing element is similar rectangular structure, and multiple evenly distributed anti-loosening convex hulls are arranged on width direction side surface, and the anti-loosening convex hull forms interference fit with sealing groove inner wall after assembly;The ratio of the long diameter and short diameter of the cross section of the sealing element is 1.6~1.8, and the groove depth of the sealing groove is greater than groove width, and the ratio of groove depth and groove width is 1.2~1.3.The utility model discloses an anti-drop axial sealing structure for automobile electric power steering device, designs the rectangular groove into sealing groove, by reasonably setting groove depth and groove width ratio and the short diameter and short diameter ratio of sealing element, again cooperation setting of convex hull, both ensure assembly smoothness, and ensure cooperation stability.

Description

Technical Field

[0001] This utility model belongs to the technical field of vehicle steering systems. Specifically, this utility model relates to an anti-detachment axial sealing structure for an electric power steering device for automobiles. Background Technology

[0002] Electric power steering (EPS) systems are widely used in modern automobiles, and their safety and reliability are paramount. Located in the chassis, the EPS system faces a complex and harsh external environment, making it highly susceptible to intrusion by mud, water, dust, and other impurities. Therefore, its sealing performance is extremely critical. Traditional sealing components employ a circular cross-section in the linear diameter, and their groove structure is designed based on the national standard (GB_3452.3-2005 Dimensions and Design Calculation Criteria for O-rings for Hydraulic and Pneumatic Use) using a compression method, resulting in a shallow axial groove depth. During actual assembly, if the seal is installed facing downwards, it is highly susceptible to partial detachment from the groove, leading to abnormal compression and damage during assembly, or even the seal falling entirely out of the groove, significantly impacting assembly processability.

[0003] Furthermore, during vehicle operation, factors such as vibration (frequency range 5-200Hz), impact (maximum impact force up to 500N), and temperature changes (-30℃-120℃) experienced by the chassis can exacerbate the risk of seal failure in traditional sealing structures. Seals are prone to displacement and deformation, resulting in increased sealing gaps (maximum gaps can reach over 0.5mm). This allows impurities such as mud, water, and dust to enter the electric power steering system, reducing its lifespan (average lifespan shortened by 20%-30%) and increasing the probability of malfunctions (failure rate increased by 18%-25%). Consequently, this affects the normal operation of the electric power steering system and may even threaten driving safety.

[0004] The existing technology has the following technical problems: (1) Poor assembly processability: Traditional sealing structures have a circular normal cross section and shallow sealing groove. Under certain assembly directions, the seal is prone to partial or complete detachment from the sealing groove, resulting in frequent damage to the seal during assembly, which increases assembly difficulty and time cost, and reduces production efficiency.

[0005] (2) Low sealing reliability: When a car is in motion, the chassis faces complex working conditions, and traditional sealing structures are difficult to effectively cope with factors such as vibration, impact and temperature changes. Under the influence of these factors, the seals are prone to displacement and deformation, which increases the sealing gap, making it easy for impurities such as mud, water and dust to enter the electric power steering system, reducing the service life of the system and increasing the probability of failure.

[0006] Chinese Patent Application No. 201310309911.8 discloses a steering shaft sealing gasket assembly, including a sealing gasket, a sealing gasket support, a bearing, a sponge, and a bushing. The sealing gasket is annular, and an annular sealing groove is provided at the junction of the sealing gasket and a through hole in the front bulkhead of the vehicle body, with the sealing groove fitting against the inner side of the front bulkhead. The sealing gasket support is installed on the outer side of the portion of the sealing gasket located inside the front bulkhead. The bearing, sponge, and bushing are all located inside the annular structure of the sealing gasket, arranged from bottom to top as the bearing, sponge, and bushing. However, the technical solution disclosed in this patent document also fails to solve the aforementioned technical problem.

[0007] An anti-disengagement axial sealing structure for an electric power steering system for automobiles is provided, particularly concerning how to ensure both smooth assembly and stable fit. Utility Model Content

[0008] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention provides an anti-disengagement axial sealing structure for automotive electric power steering systems, the purpose of which is to ensure both smooth assembly and stable fit.

[0009] To achieve the above objectives, the technical solution adopted by this utility model is as follows: an anti-detachment axial sealing structure for an electric power steering device for automobiles, including a sealing groove provided on the handpiece and a sealing element installed in the sealing groove; The sealing groove is a rectangular groove structure, and the groove depth and groove width are matched to form a full circumferential constraint on the sealing element; The seal has a rectangular cross-section and multiple evenly distributed anti-loosening protrusions on its side in the width direction. After assembly, the anti-loosening protrusions form an interference fit with the inner wall of the sealing groove, thereby preventing the seal from flipping or falling off under vibration or impact conditions during use. The ratio of the major diameter to the minor diameter of the sealing element is 1.6 to 1.8, and the depth of the sealing groove is greater than the width of the groove, with a ratio of the groove depth to the groove width of 1.2 to 1.3.

[0010] The ratio of the depth to the width of the sealing groove is 1.25, and the ratio of the minor diameter of the sealing element to the width of the sealing groove is controlled at 0.9.

[0011] The sealing groove has guide bevels on both sides of the groove opening, with an angle of 3° to 5° and a bevel length to groove depth ratio of 1:12 to 1:15, to facilitate the introduction of the sealing element.

[0012] The minimum wall thickness of the sealing groove edge is ≥1.6mm, and the ratio of the wall thickness to the groove depth is 0.5 to 0.6.

[0013] The anti-loosening protrusions are evenly arranged around the circumference of the seal, with a quantity of 12 to 16, and the ratio of the spacing between the anti-loosening protrusions to the circumference of the seal is 1:14 to 1:15.

[0014] The width of the anti-loosening protrusion is 0.1 to 0.15 mm greater than the width of the sealing groove, and the height is 1.8 to 2.2 mm.

[0015] The seal is made of nitrile rubber.

[0016] The seal has a 20° pointed structure at both ends of its cross-section to form an assembly guide and improve the demolding performance of the seal.

[0017] The present invention relates to an anti-detachment axial sealing structure for an electric power steering device for automobiles. The sealing groove is designed as a rectangular groove. By reasonably setting the ratio of groove depth to groove width and the ratio of the short diameter to the short diameter of the sealing element, and with the setting of the convex bulge, both smooth assembly and stable fit are ensured. Attached Figure Description

[0018] This manual includes the following figures, which illustrate the following: Figure 1 This is a schematic diagram of the sealing component structure; Figure 2 This is an enlarged view of the anti-loosening convex bulge; Figure 3 This is a diagram showing the dimensions and fit of the anti-loosening convex bump. Figure 1 ; Figure 4 This is a diagram showing the dimensions and fit of the anti-loosening convex bump. Figure 2 ; Figure 5 This is a schematic diagram of the sealing groove; The markings in the diagram are: 1. Anti-loosening protrusion; 2. Seal body; 3. Seal groove; 4. Normal section of seal; 5. Normal section of seal; 6. Fitting area. Detailed Implementation

[0019] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of this utility model, and to facilitate its implementation.

[0020] like Figures 1 to 4As shown, this utility model provides an anti-disengagement axial sealing structure for an automotive electric power steering device, including a sealing groove 3 on the handpiece and a sealing element installed in the sealing groove 3; the sealing groove 3 is a rectangular groove structure, and the groove depth and groove width are matched to form a full circumferential constraint on the sealing element; the sealing element has a rectangular cross-section, and the sealing element has multiple evenly distributed anti-loosening protrusions 1 on its side in the width direction. After assembly, the anti-loosening protrusions 1 form an interference fit with the inner wall of the sealing groove 3, thereby preventing the sealing element from flipping or falling off under vibration or impact conditions during use; the ratio of the major axis to the minor axis of the sealing element's cross-section is 1.6 to 1.8; the groove depth of the sealing groove 3 is greater than the groove width, and the ratio of the groove depth to the groove width is 1.2 to 1.3.

[0021] Specifically, traditional seals mostly use ordinary rubber with a Shore hardness of 60-65HA, which lacks elasticity and has poor corrosion resistance under chassis operating conditions of -30℃ to 120℃. In this invention, the seal is made of NBR (nitrile butadiene rubber), which is resistant to immersion in mud and water (volume change rate ≤5% after 240 hours) and oil corrosion (mass change rate ≤3% after 168 hours). This material can maintain good elasticity (elastic deformation recovery rate ≥90%) within a temperature range of -30℃ to 120℃ (fully covering the normal operating conditions of automotive chassis), making it fully adaptable to the harsh environment of the chassis. The seal has a Shore hardness of 70-80HA. Within this hardness range, it can still maintain an elastic deformation recovery rate of ≥90% at a low temperature of -30℃, avoiding low-temperature hardening and cracking. It does not soften at a high temperature of 120℃, preventing the seal from being squeezed out of the sealing groove 3 due to insufficient hardness. At the same time, NBR has excellent injection molding performance and can accurately form irregular structures with "quasi-rectangular cross-section + small-sized protrusions", avoiding material shortage or breakage of the protrusions during processing (processing qualification rate ≥98%).

[0022] Preferably, the ratio of the depth to the width of the sealing groove 3 is 1.25, and the ratio of the minor diameter of the seal to the width of the sealing groove 3 is controlled at 0.9.

[0023] Preferably, the sealing groove 3 has guide bevels on both sides of the groove opening, with the bevel angle being 3° to 5°, and the ratio of the bevel length to the groove depth being 1:12 to 1:15, so as to facilitate the introduction of the sealing element.

[0024] Preferably, the minimum wall thickness of the sealing groove 3 is ≥1.6mm, and the ratio of wall thickness to groove depth is 0.5 to 0.6.

[0025] Preferably, the anti-loosening protrusions 1 are evenly arranged around the circumference of the seal, with a quantity of 12 to 16, and the ratio of the spacing of the anti-loosening protrusions 1 to the circumference of the seal is 1:14 to 1:15.

[0026] Preferably, the width of the anti-loosening protrusion 1 is 0.1 to 0.15 mm greater than the width of the sealing groove 3, and the height is 1.8 to 2.2 mm.

[0027] Preferably, the seal has a 20° pointed structure at both ends of its cross-section to form an assembly guide and improve the seal's demolding performance. Example

[0028] like Figure 3 As shown, in this embodiment, the sealing element has an irregular cross-sectional shape, resembling a rectangle, with the following dimensions: major diameter (corresponding to the depth direction of the sealing groove 3) of 3.8 mm and minor diameter (corresponding to the width direction of the sealing groove 3) of 2.2 mm. Rectangular ribs with a width of 1.42 mm are also provided along both sides of the contour, and the width of the top and bottom sides of the cross-section is 1.2 mm. All sharp corners of the cross-section are designed with rounded edges (R-curves). Because the sealing cross-section adopts a shape that is pointed at both ends (angle of 20°) and wider in the middle, the ratio of the width at both ends to the width in the middle is 1.2 mm / 2.2 mm = 0.55. The advantage of this design is that during the initial assembly stage, the narrower width of the insertion part compared to the sealing groove 3 and the 20° angle provide guiding characteristics, resulting in better assembly process characteristics. This shape design also facilitates demolding of the part from the mold cavity during manufacturing.

[0029] The seal has a rectangular cross-section with a major diameter (3.8 mm) to minor diameter (2.2 mm) ratio of 1.72:1. The theoretical single-sided clearance of the rectangular sealing groove 3 is 0.1 mm, preventing the seal from flipping within the groove. In areas without anti-loosening protrusions 1, there is no radial compression during initial installation, only axial compression. Anti-loosening is achieved through a shaped cross-section and interference fit design: traditional circular seals have line contact with the groove wall and lack anti-loosening structures, making them prone to detachment during assembly.

[0030] In addition, after the seal assembly is subjected to compression deformation, "the rectangular cross section of the seal makes surface contact with the groove wall (while the traditional circular seal makes line contact), which increases the sealing reliability."

[0031] The anti-loosening protrusion 1 on the seal and the mating section of the sealing groove 3 are as follows: Figure 4 The anti-loosening protrusion 1 is uniformly distributed on the side in the width direction. The width of the anti-loosening protrusion 1 is 2.45mm and the height of the anti-loosening protrusion 1 is 2mm.

[0032] In this embodiment, the arrangement of the protrusions along the circumference of the seal is optimized, with the ratio of the spacing between the anti-loosening protrusions 1 to the circumference being 30.3:424.9. Fourteen anti-loosening protrusions 1 are provided. The equidistant arrangement of the protrusions improves the anti-drop performance. Traditional sealing structures lack anti-drop auxiliary design, or the equidistant design is unreasonable. During assembly, the seal is easily detached from the groove as a whole, or the protrusions protrude from the sealing groove 3 due to unreasonable protrusion spacing, causing damage during installation and making it difficult to detect, thus creating potential sealing hazards. Actual assembly verification shows that the rubber parts between the protrusions, due to the reasonable design, will not detach from the sealing groove 3 during installation. This design greatly enhances the stability of the fit between the seal and the sealing groove 3, preventing flipping or detachment during assembly.

[0033] The principle behind preventing falls is explained below: Anti-loosening protrusions 1 are provided on the side of the seal in the width direction. The width of the protrusions is 0.1-0.15mm larger than the width of the sealing groove 3 (on one side). Due to the overall cross-sectional shape being pointed at both ends and wide in the middle, and having features such as initial installation guidance, an interference fit of "can be installed and tightens after installation" is formed. After assembly, the anti-loosening protrusions 1 generate continuous extrusion force with the groove wall to prevent the seal from loosening. The equidistantly arranged anti-loosening protrusions 1 form a multi-point radial constraint. During assembly, the anti-loosening protrusions 1 contact and guide the groove wall one by one to avoid the seal from tilting and falling out locally. During use, the 14 anti-loosening protrusions 1 simultaneously bear the vibration and impact force, disperse local stress, and prevent the seal from falling out of the groove due to excessive force at a single point. The assembly qualification rate is increased to over 98%.

[0034] like Figure 4 and Figure 5 As shown, the sealing groove 3 on the sealing component is designed as a rectangular groove. The groove depth (long side direction) matches the long diameter of the sealing component and is set to 3mm (an increase compared to the traditional sealing groove 3 depth). The groove width (short side direction) matches the short diameter of the sealing component, ensuring that the convex bulge can be squeezed against the groove wall. The groove opening of the sealing groove 3 has a 4° bevel angle, which facilitates the introduction of the sealing component and further improves assembly convenience. This deep groove structure provides a more stable installation base for the sealing component, fundamentally solving the problem of easy detachment of traditional shallow grooves. Traditional grooves are shallow circular grooves with no guiding structure at the groove opening and no clear design for the edge wall thickness, which easily leads to deformation of the groove body due to assembly force.

[0035] In this embodiment, the optimization points are as follows: The groove structure is designed as a rectangular groove with a depth of 3mm and a width of 2.4mm (in the middle position). The depth-to-width ratio is 1.25, and the deep groove structure enhances the wrapping of the seal. The ratio of the short diameter of the seal to the groove width is 2.2:2.43. Combined with a single-sided interference of 0.1mm for the convex bulge, it ensures both smooth assembly and stable fit, solving the problem of "easy detachment" in traditional shallow groove structures.

[0036] Groove design: A 4° bevel (on both sides) is added, with the bevel length to groove depth ratio close to 1:14, which facilitates the introduction of the seal and reduces assembly resistance; Edge wall thickness: The minimum wall thickness of the edge of the sealing groove 3 is ≥1.6mm, and the ratio of wall thickness to groove depth is 1.6:3. This ensures that the groove does not deform under impact, while avoiding an increase in the weight of the parts due to excessive wall thickness, thus balancing structural strength and lightweight requirements.

[0037] Optimizing the ratio of sealing cross-section to groove depth solves the problems of displacement and vibration failure: This utility model changes the sealing cross-section to a near-rectangular shape (3.8mm major diameter, 2.44mm minor diameter), and the sealing groove depth is simultaneously adapted to 3mm, so that the ratio of the major diameter to the groove depth of the seal reaches 1:1.27, which is a significant improvement over the groove depth of traditional structures. The deep groove structure provides full-depth constraint for the seal, and combined with the directional limiting effect of the near-rectangular cross-section, it can effectively limit the axial displacement of the seal under vibration and impact conditions, and greatly reduce the risk of vibration failure.

[0038] In this embodiment, the sealing element is implemented as follows: 1. Assembly preparation: Align the irregular-shaped seal with the shape of the sealing groove 3 of the matching part (there is a foolproof design here). Since the outline of the irregular-shaped seal is designed to match the shape of the sealing groove 3 of the matching part, it will be impossible to install if the installation direction is incorrect, which can effectively prevent incorrect installation.

[0039] 2. Seal Installation: During installation, accurately place the seal with the anti-loosening protrusion 1 into the rectangular sealing groove 3. Because the seal has a long strip cross-section and the anti-loosening protrusions 1 are evenly distributed on both sides, during placement, the anti-loosening protrusions 1 gradually come into contact with and are squeezed against the inner walls of both sides of the sealing groove 3.

[0040] 3. Assembly and Fixing: Press the seal deeper into the groove. As the installation depth increases, the compressive force between the convex bulge and both sides of the sealing groove 3 gradually increases, firmly fixing the seal within the sealing groove 3 and preventing it from flipping inside. This process effectively prevents the seal from loosening during assembly and subsequent use.

[0041] The anti-detachment axial sealing structure for the automotive electric power steering system of this embodiment has the following advantages: 1. Improvement in both assembly processability and yield rate: The innovative design employs a composite structure of "quasi-rectangular irregular cross-section + 20° wedge-shaped guide angle" and a 34° double-sided guide angle design for the sealing groove, fundamentally solving the orientation deviation problem in the assembly of traditional circular seals. Fourteen equidistant anti-loosening protrusions 1 form a 0.1-0.15mm single-sided interference fit with the sealing groove 3, constructing a three-in-one assembly mechanism of "guidance-fixation-anti-detachment." This increases the assembly qualification rate from 75%-82% of the traditional structure to over 98%, reduces assembly time by 35%-40%, and simultaneously reduces the seal breakage and scrap rate during the assembly stage by over 60%.

[0042] The improved sealing structure effectively solves the problem of traditional seals easily coming off or falling off during assembly, significantly improving assembly efficiency, reducing product scrap rate caused by seal assembly problems, and improving overall product quality.

[0043] 2. Significantly enhanced sealing reliability and environmental adaptability: It uses weather-resistant NBR nitrile rubber (tested to show a volume change rate of ≤5% after 240h immersion in mud and water, and a mass change rate of ≤3% after 168h oil corrosion), combined with precise adjustment of 70-80HA Shore hardness, and maintains an elastic deformation recovery rate of ≥90% within the rated operating temperature range of -30℃ to 120℃; through the collaborative design of "3mm deep groove constraint structure + rectangular cross-section directional limit", and the optimization of dual parameters of 80%-88% volume ratio and 20%-30% compression, the sealing gap is controlled within the micron-level range of 0.05-0.1mm, the impurity intrusion rate is reduced by more than 90%, and the MTBF (mean time between failures) of the electric power steering system is extended by 25%-30%.

[0044] Optimization ensures that the seals maintain good sealing performance under complex working conditions, effectively preventing the intrusion of impurities such as mud, water, and dust. This improves the waterproof and dustproof capabilities of the electric power steering system, extends the service life of the system, and enhances the safety and stability of vehicle operation.

[0045] 3. Refined control of production and manufacturing costs: The seal is made of NBR material using a one-time injection molding process (processing qualification rate ≥98%), eliminating the need for additional secondary processing steps; the deep groove structure design ensures that the minimum wall thickness of the sealing groove 3 edge is precisely controlled to ≥1.6mm, achieving lightweight design while ensuring structural strength, and reducing material loss of a single sealing groove 3 by 12%-15%; the improved assembly efficiency directly reduces labor input costs, and the overall production cost is reduced by 18%-22% compared to traditional sealing structures.

[0046] 4. Systematic reduction in after-sales maintenance costs: Improved sealing reliability reduces the after-sales failure rate of electric power steering systems from the traditional 8%-12% to below 2%, and reduces the cost of a single repair (including labor and spare parts) by 400-600 yuan per unit; the extended service life of the device also reduces the frequency of replacement. Over the entire life cycle of the vehicle, the operation and maintenance costs related to sealing are reduced by 65%-70%, significantly improving the economic benefits for end users.

[0047] 5. Enhance market competitiveness: By adopting the sealed structure of this embodiment, the performance and reliability of the electric power steering system in automobiles are significantly improved, making automobiles equipped with this system more competitive in the market and helping companies expand their market share and increase economic benefits.

[0048] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. An anti-detachment axial sealing structure for an automotive electric power steering system, characterized in that: Includes a sealing groove provided on the contact piece and a sealing element installed in the sealing groove; The sealing groove is a rectangular groove structure, and the groove depth and groove width are matched to form a full circumferential constraint on the sealing element; The seal has a rectangular cross-section and multiple evenly distributed anti-loosening protrusions on its side in the width direction. After assembly, the anti-loosening protrusions form an interference fit with the inner wall of the sealing groove. The ratio of the major diameter to the minor diameter of the sealing element is 1.6 to 1.8, and the depth of the sealing groove is greater than the width of the groove, with a ratio of the groove depth to the groove width of 1.2 to 1.

3.

2. The anti-detachment axial sealing structure according to claim 1, characterized in that: The ratio of the depth to the width of the sealing groove is 1.25, and the ratio of the minor diameter of the sealing element to the width of the sealing groove is controlled at 0.

9.

3. The anti-detachment axial sealing structure according to claim 1 or 2, characterized in that: The sealing groove has guide bevels on both sides of the groove opening, with an angle of 3° to 5° and a ratio of bevel length to groove depth of 1:12 to 1:15, to facilitate the introduction of the sealing element.

4. The anti-detachment axial sealing structure according to any one of claims 1 to 3, characterized in that: The minimum wall thickness of the sealing groove edge is ≥1.6mm, and the ratio of the wall thickness to the groove depth is 0.5 to 0.

6.

5. The anti-detachment axial sealing structure according to any one of claims 1 to 3, characterized in that: The anti-loosening protrusions are evenly arranged around the circumference of the seal, with a quantity of 12 to 16, and the ratio of the spacing between the anti-loosening protrusions to the circumference of the seal is 1:14 to 1:

15.

6. The anti-detachment axial sealing structure according to any one of claims 1 to 3, characterized in that: The width of the anti-loosening protrusion is 0.1 to 0.15 mm greater than the width of the sealing groove, and the height is 1.8 to 2.2 mm.

7. The anti-detachment axial sealing structure according to any one of claims 1 to 3, characterized in that: The seal is made of nitrile rubber.

8. The anti-detachment axial sealing structure according to any one of claims 1 to 3, characterized in that: The sealing element has a 20° pointed angle structure at both ends of its cross-section.

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