A method of improving the life of a multilayer rod end intramedullary spacer

Abstract

The application discloses a method for prolonging the service life of an inner spacer of a multilayer rod end knuckle, which increases the thickness of the outermost spacer at both ends in the outward sleeve direction to improve the radial bearing capacity of both ends, and the starting point A of the thickness increase of the outermost spacer is close to the vertical line between the endpoint of the outward convex arc S21 at the same end of the inner side wall of the outer sleeve and the axis of the mandrel; a straight line segment L11 is arranged between the point A and the end of the rod end knuckle in the axial section to increase the thickness of both ends of the outermost spacer, and the included angle E between the straight line segment L11 and the axis of the mandrel is in the range of 8 DEG <=E<=18 DEG. The thickness of both ends of the outermost spacer is increased from the weak position of the outermost spacer, so that the radial bearing capacity of both ends of the spacer is improved; meanwhile, the thickness is increased in the form of a straight line segment, and the angle of the inclined straight line segment is controlled, so that the thickness of the spacer is increased as much as possible on the premise of ensuring sufficient deflection space, and the radial bearing capacity of the spacer is maximally improved.

Description

Technical Field

[0001] This invention relates to a method for improving the lifespan of rod end joints, and more specifically to a method for improving the lifespan of septa within multi-layer rod end joints. Background Technology

[0002] Link joints are structures at the connection points of vehicle links. During vehicle movement, they are subjected to complex load conditions such as radial, torsional, and yaw loads. For example, when a vehicle passes through a curve, the deformation of the link joint is required to withstand torsional and yaw displacements, as well as radial loads.

[0003] Early rod-end joints typically used metal joints. However, metal joints have poor environmental adaptability, especially in dusty environments where they are prone to wear, leading to reduced lifespan and abnormal noises during use, thus increasing vehicle maintenance costs. Therefore, current rod-end joints usually employ multi-layered rubber joints, as seen in a series of patents previously filed by the applicant: Application No. 202110790211X, entitled "A Multi-Layer Rod-End Ball Joint and Its Design Method"; Application No. 2021107899371, entitled "A Method and Structure for Reducing the Torsional Stiffness of Multi-Layer Rod-End Ball Joints"; and Application No. 2021107899390, entitled "A Method for Improving the Tensile Strength of the Rubber Layer of a Rod-End Ball Joint," etc. This type of rod-end joint has advantages such as large torsional angle deformation capacity, certain radial load-bearing capacity, no abnormal noise, no wear, no corrosion, maintenance-free operation, and long service life.

[0004] However, the above structure also has problems. For example... Figure 1 To ensure the uniform strain characteristics of the joint, maximize the lifespan of all structural components, and facilitate mold fabrication, a structure typically employs a combination of spherical spacers of equal thickness and a cylindrical outer sleeve. To guarantee the joint's deflection characteristics, in a radial sectional view, the inner wall of the outer sleeve consists of straight lines L1' parallel to the mandrel axis at both ends, and an outwardly convex arc S1' protruding towards the outer sleeve in the middle. The outwardly convex arc S1' and the straight line L1' are smoothly connected by an inwardly concave arc S2' that inclines towards the mandrel. This results in uneven rubber thickness at both ends of the outermost layer, with the thickest point H2 being more than three times the thickness of the thinnest point H1. Consequently, the area corresponding to the radially convex arc S1' becomes the primary load-bearing area. Under large radial loads, the ends of the outermost spacer corresponding to the outer sleeve S1' are prone to breakage, affecting the overall lifespan of the joint. Summary of the Invention

[0005] This invention addresses the problem that the outermost septum of a rod end joint is prone to breakage and thus has a short lifespan. It proposes a method to improve the lifespan of the inner septum of a multi-layer rod end joint, which can increase the strength of the outermost septum and thus extend the service life of the joint.

[0006] The technical means adopted by the present invention to solve the above problems is as follows: a method to improve the service life of the inner spacer of the multi-layer rod end joint, which improves the radial bearing capacity at both ends by increasing the thickness at both ends of the outermost spacer in the direction of the outer sleeve, and the starting point A of the increase in the thickness of the outermost spacer is close to the perpendicular line between the end of the outward convex arc S21 at the same end of the inner sidewall of the outer sleeve and the axis of the mandrel; from the axial section, a straight line segment L11 is set between point A and the end of the rod end joint to increase the thickness at both ends of the outermost spacer, and the angle E between the straight line segment L11 and the axis of the mandrel is in the range of 8°≤E≤18°.

[0007] Furthermore, the distance D1 between the starting point A of the increase in the thickness of the outermost septum and the perpendicular line between the endpoint of the outward convex arc S21 at the same end of the inner sidewall of the outer jacket and the axis of the mandrel is ≤5mm.

[0008] Furthermore, from an axial cross-section perspective, the end of the outermost spacer closest to the outer sleeve is a straight segment L12 parallel to the spindle axis. Straight segments L11 and L12 are smoothly connected by a concave arc S13 that curves inward toward the spindle, with the two endpoints of the concave arc S13 located on either side of the concave endpoint of the outermost rubber layer. This design maximizes the number of outermost spacers while allowing sufficient deflection space, without affecting the deflection characteristics of the rod end joint.

[0009] Furthermore, from an axial cross-section perspective, the end of the outermost spacer near the outer jacket is still an extension S11' of the outwardly convex arc S11 in the middle of the outermost spacer. A straight segment L11 connects to the extension S11' of the outwardly convex arc S11 via a straight segment L13. Simultaneously, straight segments L11 and L13 are smoothly connected by an outwardly convex arc S14 protruding towards the outer jacket. Straight segment L13 and the extension S11' of the outwardly convex arc S11 are smoothly connected by an inwardly concave arc S15 concave towards the mandrel. The intersection of straight segment L11 and the outwardly convex arc S14 is close to the perpendicular line between the concave end point of the outermost rubber layer and the mandrel axis. This ensures that the thickness of the outermost spacer is increased in areas with greater outer rubber thickness, thereby maximizing the radial load-bearing capacity of the spacer.

[0010] Furthermore, the distance D2 between the intersection of the straight line segment L11 and the convex arc S14 and the perpendicular line between the concave end point of the outermost rubber layer and the axis of the mandrel is ≤7mm.

[0011] Furthermore, from an axial cross-section perspective, the outermost bulge S11 at the middle of the side closest to the outer jacket is smoothly connected to the straight segment L11 by an inwardly concave arc S12 that curves inward toward the spindle. This allows for the adjustment of the inclination angle range of the straight segment L11.

[0012] Furthermore, multiple reinforcing ribs are arranged along the axial direction of the mandrel on the side of the outermost spacer closest to it, and each reinforcing rib is separated from the adjacent spacer by a cavity without rubber filling. The cavity offsets the increase in stiffness caused by the reinforcing ribs.

[0013] Furthermore, the number of reinforcing ribs is 6-10, evenly distributed along the circumference.

[0014] Furthermore, during vulcanization, the cavity is filled with a double-layered filler. After vulcanization is complete, the inner layer of the filler is removed to form the cavity.

[0015] Furthermore, the double-layered filler consists of a high-temperature resistant sealing material wrapped around the metal strip. After vulcanization, the metal strip is removed, forming a cavity.

[0016] Furthermore, each layer of spacers is divided into two equal halves, with the openings between adjacent layers staggered at 60°. During vulcanization, six injection holes are set in each rubber layer, and all injection holes at the same angle in all rubber layers form a straight injection line. The included angle between any two adjacent injection lines is 60°, and the spacer opening is located on the angle bisector of the included angle between two adjacent injection lines. This ensures balanced injection at the spacer openings.

[0017] The beneficial effects of this invention are: 1. This invention improves the radial load-bearing capacity at both ends of the spacer by increasing the thickness from the weakest point of the outermost spacer. At the same time, it increases the thickness by using straight segments and controlling the inclination angle of the straight segments. Under the premise of ensuring sufficient deflection space, the thickness of the spacer is increased as much as possible to maximize the radial load-bearing capacity of the spacer.

[0018] 2. The thickness of the main load-bearing area in the middle region of the outermost partition of the present invention remains unchanged, only the thickness at both ends is increased. Therefore, it can still ensure the performance requirements of equal stress on the entire rod end joint. Furthermore, by improving the load-bearing capacity at both ends, the risk of breakage of the outermost partition at the rubber thickness change point is reduced, which means the weak point of the partition is eliminated.

[0019] 3. The present invention improves the strength of the spacer by setting multiple reinforcing ribs on the side of the outermost spacer closest to the mandrel. At the same time, the area between the reinforcing ribs and the adjacent spacers is set as a cavity without rubber filling to offset the increase in stiffness brought by the reinforcing ribs, so that the total radial stiffness of the rod end joint is not affected.

[0020] 4. During vulcanization, the present invention uses a double-layered filler in the cavity. After vulcanization, only the inner layer is removed, which allows a cavity structure to be formed in a narrow space.

[0021] 5. The rubber layer of this invention uses six-point injection, and the injection lines are distributed at 60°, so that the distance from the injection point to the opening of the partition is equal on both sides. This ensures that the rubber is filled at the opening of the partition at the same time, avoiding misalignment, uneven rubber layer thickness and other defects, and ensuring product performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the axial cross-section of the rubber between the outer sleeve of the rod end joint and the outermost septum in the prior art (only the cross-sectional lines of the rubber layer are shown in the figure). Figure 2 This is a schematic axial cross-sectional view of the rubber between the rod end joint sleeve and the outermost septum in Example 1 (only the cross-sectional line of the rubber layer is shown in the figure). Figure 3 for Figure 2 A magnified diagram showing the increased thickness of the outermost septum at both ends of the joint; Figure 4 This is a magnified schematic diagram showing the increased thickness of the outermost septum at both ends of the joint, as described in Example 2. Figure 5 This is a magnified schematic diagram showing the increased thickness of the outermost septum at both ends of the joint, as described in Example 3. Figure 6 This is a radial cross-sectional view of the joint septum and rubber layer at the rod end in Example 4; Figure 7 for Figure 6 Enlarged view of a portion; Figure 8 for Figure 7 Schematic diagram of filling the cavity during vulcanization; Figure 9 This is a cross-sectional view along the axial direction of Example 4 when reinforcing ribs are provided on the outermost spacer (only the cross-sectional lines of the rubber layer and the spacer are shown in the figure). Figure 10 for Figure 9 A schematic diagram of the filling of the cavity during vulcanization (only the cross-sectional lines of the rubber layer and the spacer are shown in the figure). Figure 11 This is a schematic diagram of the rod end joint along the axial end face direction in Embodiment 5; Figure 12 for Figure 11 Enlarged view of a portion; In the diagram: 1. Outer jacket, 2. Outermost rubber layer, 3. Outermost partition, 31. Reinforcing rib, 32. Cavity, 33. Filler, 4. Mandrel, 5. Boss, 6. Partition, 61. Opening, 7. Rubber layer, 8. Injection hole, 81. Injection line. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. The drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Example 1

[0024] A method for improving the lifespan of septa within multilayer rod end joints, such as Figure 2 As shown, the rod end joint includes an innermost spindle 4, an outermost outer sleeve 1, and multiple rubber layers 7 and spacers 6 located between the spindle 4 and the outer sleeve 1. Figure 2 and Figure 3 As shown, viewed from the axial section, the endpoints of the two ends of the outward convex arc S21 at the middle of the inner wall of the outer sleeve 1 are B, and the two ends of the inner wall of the outer sleeve 1 are straight segments L21. Between the outward convex arc S21 and the straight segment L21, there is an inward concave arc S22 that is recessed towards the spindle 4. The outermost spacer 3 has an outward convex arc S11 at the middle of the side closest to the outer sleeve 1, which protrudes towards the outer sleeve 1.

[0025] To improve the strength of the outermost spacer 3, in this embodiment, as follows: Figure 2 and Figure 3 As shown, from the axial section, the length of the convex arc S11 is controlled to point A, and the shape of the joint end near point A is set as a straight segment L11 that smoothly connects with the convex arc S11. The angle E between the straight segment L11 and the mandrel axis is controlled within the range of 8°≤E≤18°. This avoids both situations where E is too small, resulting in insufficient deflection space and weakened product deflection load-bearing capacity, and where E is too large, leading to insufficient increase in the thickness of the outermost spacer 3, thus failing to improve its radial load-bearing capacity. At this point, the straight segment L11 is tangent to the convex arc S11 at point A, meaning L11 is the tangent to S11, allowing for a smooth connection. Furthermore, the distance D1 between the perpendicular lines from point A to point B and the mandrel axis must satisfy: D1≤5mm. This allows for increasing the thickness starting from the weakest point of the outermost spacer 3, effectively improving its radial load-bearing capacity.

[0026] In this embodiment, as Figure 3As shown, viewed from the axial section, the outermost partition 3, near the outer sleeve side, is shaped as a straight segment L12 parallel to the spindle axis. The straight segment L12 and straight segment L11 are smoothly connected by an inwardly recessed arc S13 that curves inward toward the spindle 4. Furthermore, the intersection point C1 between the inwardly recessed arc S13 and the straight segment L11, and the intersection point C2 between the inwardly recessed arc S13 and the straight segment L12, are located on either side of the perpendicular line V between the concave end of the outermost rubber layer and the spindle axis. This makes the contact surface between the outermost partition 3 and the outermost rubber layer 2 at a location with greater rubber thickness a straight segment L11 with an angle E, ensuring that the outermost partition 3... Within this interval, the thickness gradually increases from the middle to both ends. The greater the rubber thickness in the same radial direction, the greater the thickness of the outermost partition 3. While ensuring the deflection deformation space, when subjected to radial load, the outer jacket 1 squeezes the outermost rubber 2. At both ends of the outermost rubber 2, due to the reduced rubber thickness, the deformation also decreases. The ability to transfer the load to the outermost partition 3 under load is enhanced. At the same time, due to the increased thickness of the outermost partition 3 at this point, it can withstand a greater load, thereby reducing the load on the outermost partition 3 in the outward convex arc S11 interval. Therefore, the service life of the outermost partition 3 can be extended. Example 2

[0027] This embodiment is basically the same as the above embodiment, except that: Figure 4 As shown, from the axial section, the outermost partition 3 is smoothly connected to the outer convex arc S11 near the outer sleeve 1 by the concave arc S12 that is recessed towards the spindle 4. This is because, in order to ensure that the angle range of the straight segment L11 is 8°≤E≤18°, the straight segment L11 and the outer convex arc S11 can be smoothly connected, so as to avoid the smoothness of the outermost rubber 2 surface at this point and prevent wrinkles or cracks from easily appearing. However, if the distance D1 between the perpendicular line between point A and point B and the spindle axis meets the requirements, the tangent of the outer convex arc S11 at point A can never meet the requirement of 8° to 18°. At this time, the concave arc S12 is needed to realize the connection between the straight segment L11 and the outer convex arc S11. Example 3

[0028] This embodiment can be a modification of either Embodiment 1 or Embodiment 2, such as... Figure 5As shown, from the axial section, the end of the outermost partition 3 near the outer jacket 1 in this embodiment is still an extension of the convex arc S11', that is, the center and radius of the convex arc S11' are the same as those of the convex arc S11. At this point, in order to ensure a smooth connection between the straight segment L11 and the convex arc S11', a straight segment L13 is set between the straight segment L11 and the convex arc S11'. The straight segment L11 and the straight segment L13 are connected by an convex arc S14 that protrudes towards the outer sleeve 1, and the straight segment L13 and the convex arc S11' are connected by an inward arc S15 that is concave towards the spindle 4. In this way, a boss 5 is formed between the convex arcs S14. At the same time, by controlling the position of the intersection point C3 between the straight segment L11 and the convex arc S14, the boss 5 is positioned as close as possible to the end of the rod end joint to maximize the radial bearing capacity of the outermost partition 3. At this point, the distance D2 between C3 and the perpendicular line V between the concave end of the outermost rubber layer and the spindle axis is required to be ≤7mm. Since the outermost rubber 2 corresponding to the outwardly convex arc S11' in the same diameter direction has an inwardly concave structure, the rubber at this point can not play a role in transmitting radial loads. It is mainly used for connection with the outer jacket 1 and the outermost partition 3, as well as stress relief. Therefore, the shape of the outermost partition 3 with the outwardly convex arc S11' will not affect the overall load-bearing capacity. Example 4

[0029] This embodiment may be an improvement on any of the above embodiments, such as... Figure 6 and Figure 7 As shown, multiple reinforcing ribs 31 are provided on the side of the outermost spacer 3 facing the spindle 4. The length of the reinforcing ribs 31 is arranged along the axial direction of the spindle 4, and they are evenly distributed in the circumferential direction. The number can be 6-10, depending on the size of the rod end joint and the load-bearing requirements. Although the load-bearing capacity is improved by adding reinforcing ribs 31 to provide support for the outermost spacer 3, the distance between it and the adjacent spacer 6 is reduced, which means the compression stroke is reduced. Therefore, a cavity 32 is set between the reinforcing rib 31 and the adjacent spacer 6. When subjected to radial load, the cavity 32 can become a compression space, which will not affect the overall performance.

[0030] Because the thickness of the inner rubber layer 7 in this product is relatively thin, and the thickness at the cavity 32 is even smaller, and as... Figure 9 As shown, the cavity 32 is a curved, elongated strip. Therefore, if a conventional mold part is used to fill the cavity 32 during vulcanization, this mold part may become impossible to remove after vulcanization, thus preventing the formation of the cavity 32. To avoid this situation, as... Figure 8 and Figure 10As shown, the filling material 33 in the cavity 32 during vulcanization can be made by wrapping a high-temperature resistant sealing material around a thin metal strip. The metal strip provides support, and the high-temperature resistant sealing material isolates the rubber from the metal strip. After vulcanization is completed, the metal strip can be removed to form the cavity 32. The high-temperature resistant sealing material can remain in the cavity 32 without affecting the performance. At the same time, it can also isolate the reinforcing rib 31 and the partition 6 from the outside world, thus playing a protective role. Example 5

[0031] This embodiment is an improvement on the rod end joint forming method, such as... Figure 11 and Figure 12 As shown, each spacer 6 is divided into two equal halves, and two openings 61 are formed between two spacers 6 in the same layer. The openings 61 between adjacent layers of spacers 6 are staggered at 60°. During vulcanization, six injection holes 8 are evenly arranged in each rubber layer 7. A straight injection line 81 is formed between all injection holes 8 at the same angle in all rubber layers 7. The included angle between any two adjacent injection lines 81 is 60°, and the opening 61 of the spacer 6 is located on the angle bisector of the included angle between two adjacent injection lines 81. In this way, the distance between an opening 61 and its four nearby injection holes 8 is approximately equal. During vulcanization, the rubber material at the four nearby injection holes 8 can reach the same opening 61 at approximately the same time, so that the rubber material is filled at the opening 61 simultaneously, achieving a balanced injection state and avoiding misalignment or uneven rubber layer thickness at the opening 61. Example 6

[0032] In this embodiment, the relationship between the radial ultimate fatigue load F (where the fatigue cycles are 2 million) borne by the product and the thickness H and width L of the outer jacket 1 is: F = 2.35L + 4.15H - 84, which limits L ≥ 28mm and H ≥ 7mm, so that the formed rod end joint can meet the assembly space requirements and avoid excessive deformation of the outer jacket 1 when bearing load.

[0033] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the invention, which should be defined by the claims.

Claims

1. A method for improving the lifespan of the septum within a multi-layer rod end joint, characterized in that: The radial bearing capacity at both ends is improved by increasing the thickness at both ends of the outermost partition (3) in the direction of the outer jacket (1), and the starting point A of the increase in the thickness of the outermost partition (3) is close to the perpendicular line between the end of the convex arc S21 at the same end of the inner wall of the outer jacket (1) and the axis of the spindle. From the perspective of the axial section, a straight segment L11 is set between point A and the end of the rod end joint to increase the thickness at both ends of the outermost diaphragm (3), and the angle E between the straight segment L11 and the axis of the mandrel (4) is 8°≤E≤18°. From the axial section, the end of the outermost partition (3) near the outer jacket (1) is still the extension S11' of the outermost partition (3) at the middle of the outermost partition (3). The straight segment L11 and the extension S11' of the outermost partition S11 are connected by the straight segment L13. At the same time, the straight segment L11 and the straight segment L13 are smoothly connected by the outermost partition S14 protruding towards the outer jacket (1). The straight segment L13 and the extension S11' of the outermost partition S11 are smoothly connected by the inner concave arc S15 concave towards the spindle (4). The intersection of the straight segment L11 and the outermost partition S14 is close to the perpendicular line between the inner concave end of the outermost rubber (2) and the axis of the spindle (4).

2. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 1, characterized in that: The distance D1 between the starting point A of the increase in thickness of the outermost septum (3) and the end point of the outward convex arc S21 at the same end of the inner wall of the outer jacket (1) and the axis of the mandrel (4) is ≤5mm.

3. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 1, characterized in that: From the axial section, the end of the outermost partition (3) near the outer jacket (1) is a straight segment L12 parallel to the axis of the spindle (4). The straight segment L11 and the straight segment L12 are smoothly connected by an inward concave arc S13 that is recessed towards the spindle (4), and the two ends of the inward concave arc S13 are located on both sides of the inward concave end of the outermost rubber (2).

4. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 1, characterized in that: The distance D2 ≤ 7mm between the intersection of the straight line segment L11 and the convex arc S14 and the perpendicular line between the concave end of the outermost rubber (2) and the axis of the mandrel (4).

5. The method for improving the lifespan of the septum within a multi-layer rod end joint as described in claim 1 or 3, characterized in that: From the axial section, the outermost partition (3) is smoothly connected to the straight segment L11 by the outward convex arc S11 at the middle of the side close to the outer jacket (1) through the inward concave arc S12 that is recessed towards the spindle (4).

6. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 1, characterized in that: Multiple reinforcing ribs (31) are arranged along the axial direction of the mandrel (4) on the side of the outermost partition (3) near the mandrel (4), and each reinforcing rib (31) and the partition (6) near it are provided with a cavity (32) without rubber filling.

7. The method for improving the lifespan of the septum within a multi-layer rod end joint as described in claim 6, characterized in that: During vulcanization, the cavity (32) is filled with a double-layered filler (33). After vulcanization is completed, the inner layer of the filler (33) is removed to form the cavity (32).

8. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 7, characterized in that: The double-layered filler (33) consists of a high-temperature resistant sealing material wrapped around the metal strip. After vulcanization, the metal strip is removed to form a cavity.

9. The method for improving the lifespan of the intra-joint septum in a multi-layer rod end as described in claim 1, characterized in that: Each layer of partition (6) is divided into two equal parts. The openings (61) between two adjacent layers of partition (6) are staggered at 60°. During vulcanization, six injection holes (8) are set in each rubber layer (7). A straight injection line (81) is formed between all the injection holes (8) at the same angle of all rubber layers (7). The included angle between two adjacent injection lines (81) is 60°, and the opening (61) of the partition (6) is located on the angle bisector of the included angle between two adjacent injection lines (81).

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