A drive axle housing, vehicle and hydroforming process for an axle housing

Abstract

This application provides a drive axle housing, a vehicle, and a hydroforming process for the axle housing. The axle housing includes a central axle section and sleeve sections extending to both sides from the axle section. The sleeve sections and the axle section are integrally hydroformed. One end of the axle section is a bulge, and the opposite end has an insertion port for the main reducer. The bulge has a spherical wall, and a portion of the spherical wall has a flat portion and / or an arcuate portion. This application, through the design of the bulge of the axle section, achieves both bulging and clearance purposes, while also enabling the hydroforming process to successfully produce the desired product. Compared to the welding methods mentioned in the background art, the axle housing formed by this application obviously reduces the waste of welding processes, eliminates fatigue cracking problems caused by welding defects, and, compared to axle housings formed by welding or casting, the axle housing provided by this application has a significant weight reduction effect.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and more specifically to a drive axle housing, a vehicle, and a hydroforming process for the axle housing. Background Technology

[0002] The axle housing is the basic component for mounting the main reducer, differential, half-shafts, wheel hubs, and suspension. Its main function is to support and protect the main reducer, differential, and half-shafts. The middle part of the axle housing is the axle bump, which is bulged to avoid obstructing the internal components.

[0003] Because of the bulging design of the axle housing, the shape of the entire axle housing is irregular. Therefore, the axle housing of automotive drive axles is generally made by integral casting or by welding together upper and lower stamped parts. The disadvantages of integral casting are that the parts are heavy, the manufacturing cost is high, and it is not conducive to reducing fuel consumption. The disadvantages of welding the axle housing with upper and lower stamped parts are that the welding beveling process is inefficient, the weld is long, the deformation of the parts after welding is large, welding defects are difficult to avoid, and fatigue cracking and oil leakage are likely to occur. Summary of the Invention

[0004] This application provides a drive axle housing, the axle housing including an axle housing portion located in the middle and sleeve portions extending from the axle housing portion to both sides, the sleeve portions and the axle housing portion on both sides being integrally hydraulically formed; one end of the axle housing portion is a bulge portion, and the opposite end is provided with an installation port for inserting a main reducer, the bulge portion having a spherical wall, and the spherical wall portion being partially provided with a flat portion and / or an arcuate portion.

[0005] In one specific embodiment, the bulge includes a first clearance position, which corresponds to a secondary driven gear located within the axle housing. The first clearance position is offset relative to the center of the axle housing and disposed on a first side of the bulge. An arcuate portion is provided between the first clearance position and the root of the first side of the bulge. The bulge includes a second side opposite to the first side, and a planar portion is provided between the first clearance position and the root of the second side of the bulge.

[0006] In one specific embodiment, the flat portion is provided with an oil filling hole.

[0007] In one specific embodiment, the sleeve portion, from the end toward the bridge portion, sequentially includes a round pipe section, a round-square pipe transition section, a square pipe section, and a sleeve-bridge transition section.

[0008] In one specific embodiment, the upper part of the round-square tube transition section is used to connect the spring seat, and the lower part is used to connect the lower longitudinal arm bracket.

[0009] This application also provides a vehicle including the axle housing of the drive axle described in any of the preceding claims.

[0010] This application also provides a hydroforming process for axle housing, used to process the axle housing of the rear drive axle described in any of the above claims, comprising the following steps:

[0011] Prepare tube blanks;

[0012] The two ends of the tube blank are narrowed to form a narrowed tube;

[0013] The constricted tube is hydraulically formed to create a bridge section located in the middle.

[0014] In one specific embodiment, during hydroforming, a round-square tube transition section, a square transition section, and a sleeve bridge transition section are formed in sequence, which are connected to the constricted end of the constricted tube.

[0015] In one specific embodiment, the hydroforming process includes at least two hydroforming stages. In the first hydroforming stage, the cavity of the corresponding mold is cylindrical corresponding to the position of the bridge portion to regularly shape the middle part of the constricted tube. In the last hydroforming stage, the cavity of the corresponding mold is aligned with the position of the bridge portion and the outer contour of the bridge portion.

[0016] This application, through the morphological design of the bulge portion of the axle housing, achieves both the purpose of bulging and avoidance, while also enabling the hydroforming process to successfully mold the required product. Compared to the welding solutions mentioned in the background art, the axle housing formed by this application obviously reduces the waste of welding processes, eliminates fatigue cracking problems caused by welding defects, and, compared to axle housings formed by welding or casting, the axle housing provided by this application has a significant weight reduction effect.

[0017] Furthermore, from a product characteristics perspective, the dimensions of the axle housing remain constant, while the length of the sleeve can be varied according to the vehicle width, and the wall thickness of the axle housing can be adjusted according to the vehicle load. In other words, the thickness of the blank can be adjusted based on load requirements, thereby changing the axle housing thickness. Due to the characteristics of the hydraulic bulging process, changing the thickness of the axle housing only requires adjusting the plugs in the bulging mold, and changing the length only requires replacing the inserts at both ends of the mold. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the drive axle assembly in an embodiment of this application;

[0019] Figure 2 for Figure 1 A schematic diagram of the axle housing of the drive axle;

[0020] Figure 3 for Figure 2 The main view;

[0021] Figure 4for Figure 3 The left view;

[0022] Figure 5 for Figure 3 C-axis sectional view;

[0023] Figure 6 for Figure 5 Enlarged view of the location of the central bridge section;

[0024] Figure 7 for Figure 6 The diagram inside includes the driven gear, bearing housing, and half shaft;

[0025] Figure 8 for Figure 7 Sectional view along the DD direction;

[0026] Figure 9 for Figure 3 A cross-sectional view of the AA section;

[0027] Figure 10 for Figure 3 A cross-sectional view of the BB section.

[0028] Figure 1-10 The annotations in the attached figures are explained as follows:

[0029] 100-bridge housing;

[0030] 1-Circular pipe section;

[0031] 2-Round-square tube transition section;

[0032] 3-Square pipe section;

[0033] 4-Casing bridge transition section;

[0034] 5-Bridge section; 51-Bulging section; 511-Flat section; 512-Curved section; 513-Fuel filler port;

[0035] 200-Spring seat; 300-Lower longitudinal arm bracket; 400-Main reducer; 500-Sleeve flange; 600-Bearing seat; 700-Half shaft; 800-Secondary driven gear. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Please refer to Figure 1-6 , Figure 1 This is a schematic diagram of the drive axle assembly in an embodiment of this application; Figure 2 for Figure 1 A schematic diagram of the axle housing of the drive axle; Figure 3 for Figure 2 The main view; Figure 4 for Figure 3 The left view; Figure 5 for Figure 3 C-axis sectional view; Figure 6 for Figure 5 Enlarged view of position 5 on the middle bridge section.

[0038] The axle housing of the drive axle in this embodiment includes an axle housing portion 5 located in the middle and sleeve portions extending from the axle housing portion 5 to both sides, i.e. Figure 2 The left and right sides shown in the diagram represent the left and right directions of the vehicle, and the front and rear directions mentioned in this article also refer to the front and rear directions of the vehicle. The sleeve sections on both sides of the axle housing 5 are symmetrically arranged relative to the axle housing 5, and the sleeve sections and the axle housing 5 are integrally hydraulically formed. During assembly, the sleeve section is used to accommodate the half-shaft 700, and the end of the sleeve section away from the axle housing 5 is used to install a flange. The main reducer is inserted into the axle housing 5 from one end, specifically from... Figure 1 As shown in the diagram, the driving bevel gear of the main reducer is inserted into the axle housing 5 and meshes with the driven bevel gear located in the axle housing 5, thereby transmitting power to the half shaft 700. The axle housing 5 is also equipped with components such as a differential.

[0039] like Figure 2 As shown, from a front-to-back perspective, the bridge housing 5 in this embodiment includes a generally annular shell shape. The use of an annular shell here facilitates understanding the overall structure of the bridge housing 5, but in reality, the annular structure and the bulge 51 described below are a hydroformed integral structure. From a front-to-back perspective, the dimensions of the annular shell and the sleeve portion are approximately the same. Furthermore, combining... Figure 5 , 6 It is understood that the axle housing 5 includes a bulge 51 located at the rear end of the annular housing. The front opening of the axle housing 5 (not shown in the figure) forms a mounting port, that is, the front end of the annular housing is open to form a mounting port, which allows the power output part of the main reducer to be inserted. Thus, the inner side of the bulge 51 can form a cavity to accommodate and avoid the parts inside the axle housing 5.

[0040] Can continue to combine Figure 7 , 8 understand, Figure 7 for Figure 6 The diagram shows the internal components including a two-stage driven gear 800, a bearing housing 600, and a half-shaft 700. Figure 8 for Figure 7 Sectional view along the DD direction.

[0041] The secondary driven gear 800 is installed inside the bridge housing 5. The front end of the bridge housing 5 has an installation opening. When components such as the secondary driven gear 800 protrude from the annular housing in the front-rear direction, the bridge housing 5 will not interfere with the secondary driven gear 800. However, the rear end of the bridge housing 5 is not open. If the rear end of the bridge housing 5 were closed and flush with the annular housing, interference would occur when components protrude in the front-rear direction. Therefore, a protruding bulge 51 is provided to avoid obstructing the secondary driven gear 800 and other components inside the bridge housing 5. The secondary driven gear 800... Generally located off-center in the bulge 51, the bridge housing 5 also contains structures such as a bearing seat 600. The secondary driven gear 800 protrudes the largest in the front-rear direction, and must be able to avoid the secondary driven gear 800. At this time, the wall of the bulge 51 is roughly designed as a spherical wall. Of course, the spherical wall is not a complete sphere. It protrudes from the annular shell of the bridge housing 5 to the rear, forming a hemispherical wall or a small hemispherical wall. The widest position of the bulge 51 in the front-rear direction corresponds to the position of the secondary driven gear 800.

[0042] It should be emphasized that in this embodiment, the spherical wall of the bulge 51 is partially provided with a flat portion 511 and / or an arcuate portion 512, that is, the spherical wall is partially adjusted, rather than the entire wall of the non-bulge 51 being spherical. Figure 6 In the middle, the bulge portion 51 is provided with a flat portion 511 and an arcuate portion 512, which are respectively provided on both sides of the bulge portion 51 and defined as the first side and the second side, that is... Figure 6 The left and right sides are shown. They can be combined. Figure 7 Understanding that the secondary driven gear 800 is offset to the left relative to the middle of the bridge portion 5, i.e., offset to the first side, with the entire wall of the bulge portion 51 as a spherical reference, the portion of the bulge portion 51 corresponding to the secondary driven gear 800 is the first clearance position M1, used to clear the secondary driven gear 800. The right side of the first clearance position M1 has a larger inward space and a larger inward area, allowing for the creation of a flat portion 511 of a certain area. That is, the flat portion 511 is positioned between the first clearance position M1 and the root of the right side of the bulge portion 51. The inward space of the bulge portion 51 on the left side of the first clearance position M1 is relatively small, and a certain clearance distance needs to be reserved. Therefore, an arc-shaped portion 512 is provided on the left side. The arc-shaped portion 512 is positioned between the first clearance position M1 and the root of the left side of the bulge portion 51. That is, the degree and area of ​​the arc-shaped portion 512 are smaller than those of the flat portion 511. Figure 7 As shown, the root position where the bearing housing 600, the bulge 51 and the annular housing meet is the second clearance position M2 and the third clearance position M3.

[0043] It is understandable that, depending on the actual needs of obstacle avoidance, curved surfaces 512 or flat surfaces 511 can be provided on both sides. Furthermore, combined with... Figure 1 , 8It is understood that the top and bottom of the bulge 51 need to avoid the secondary driven gear 800. Since there is no more space for the top and bottom to be recessed, only the flat part 511 and the arc part 512 are provided on both sides. When the flat part 511, the arc part 512 and other parts are connected, they are all designed to be connected smoothly.

[0044] You can continue to refer to Figure 6 Understanding that the planar portion 511 corresponds to position AC, and the dashed line ABC indicates the spherical design outline, with the length of AC clearly shorter than the length of ABC, similarly, the length of the curved portion 512 is also shorter than the corresponding spherical design outline length. The bulge 51, offset from the center, maintains a roughly spherical wall design to ensure the required distance from the secondary driven gear 800, preserving its function of avoiding the secondary driven gear 800. Other positions can be recessed by a certain dimension based on the arrangement of internal parts, forming either the planar portion 511 or the curved portion 512. Thus, when the bridge portion 5 is hydroformed using a tube blank, due to local adjustments, the tube blank position corresponding to the bulge 51 does not need to be formed as a complete sphere, reducing the forming amount at the positions corresponding to the planar portion 511 and the curved portion 512, thus reducing the problem of cracking caused by excessive thinning. Simultaneously, the planar portion 511, the curved portion 512, and the connecting parts are all smoothly transitioned, which facilitates hydroforming and prevents forming failure due to abrupt changes in cross-section.

[0045] Furthermore, in this embodiment, the flat portion 511 can be provided with an oil filling port 513, that is, the position of the flat portion 511 covers the position where the oil filling port 513 needs to be set. In this way, when the oil filling bolt is screwed into the oil filling port 513, the interaction area between the oil filling bolt and the flat portion 511 is larger, and the installation is more reliable.

[0046] Please continue reading. Figure 3 and combined Figure 9 , 10 understand, Figure 9 for Figure 3 A cross-sectional view of the AA section; Figure 10 for Figure 3 A cross-sectional view of the BB section.

[0047] It is worth noting that in this embodiment, the casing section, from its end towards the bridge section 5, sequentially includes a circular tube segment, a circular-to-square tube transition section 2, a square tube segment 3, and a casing bridge section transition section 4. That is, the normally circular tube-shaped casing section is configured as a variable cross-section structure, with the main body of the casing section being the square tube segment 3. This configuration allows each part of the casing section to perform its function and facilitates the process.

[0048] Please see Figure 1The circular design of the pipe section facilitates connection with the sleeve flange 500, which can be welded. The sleeve flange 500 is used to connect to the half-shaft 700 flange. The dimensions of the circular pipe section 1 are determined by the sleeve flange 500. During processing, if the radial dimension of the selected pipe blank is large, a necking process is required at the ends. Therefore, the thickness of the circular pipe section 1 after processing will be greater than the thickness of the pipe blank. For example, if a pipe blank with a diameter of approximately 90mm is selected, a necking process can be used to obtain a circular pipe section 1 of approximately 60mm.

[0049] The upper part of the round-square tube transition section 2 can be connected to the spring seat 200, and the lower part can be connected to the lower longitudinal arm bracket. Both can be welded connections. Compared to a circle, the lower longitudinal arm bracket and the spring seat 200 can be overlapped with the circular or square area of ​​the round-square tube transition section 2 according to their shape, which is conducive to the dimensional accuracy control of the overlap part.

[0050] For the square tube segment 3, its square design facilitates the transfer and dispersion of stress concentration points in the bridge housing 100. More importantly, under the same maximum radial dimension, the perimeter of the square is obviously larger than that of the circle. This means that when the square tube segment 3 transitions to the bridge housing 5, the change in forming amount is not too abrupt, thus facilitating hydroforming; that is, the change in the sleeve bridge housing transition section 4 will be more gradual. Furthermore, setting the main body of the sleeve portion as square facilitates the control of the pipe diameter reduction process described later. Taking the aforementioned 90mm tube blank as an example, the thickness of the square tube segment 3 can be around 3.8mm. Because its perimeter is longer than that of the circular tube, its thickness encompasses that of the circular tube segment 1.

[0051] The transition section 4 of the casing bridge is the forming change area, smoothly transitioning between the square tube segment 3 and the bridge section 5, with the cross-sectional size gradually increasing and the material thickness gradually decreasing. As mentioned earlier, the transition from the square tube segment 3 to the bridge section 5, compared to the transition from the round tube to the bridge section 5, is more conducive to hydroforming and stress transfer and dispersion. Experimental verification shows that in the prior art, when the bridge shell of the welded structure transitions from the round tube to the bridge section, the stress value reaches 153 MPa, and the full-load wheelbase deformation reaches 1.308 mm. In contrast, the stress distribution of the bridge shell 100 in this embodiment is more uniform, the stress value can be reduced to 123 MPa, and the full-load wheelbase deformation is 1.088 mm, which can improve performance by 20% and achieve the weight reduction of the bridge shell 100.

[0052] This application embodiment also provides a hydroforming process for the bridge housing 100 described above, as follows:

[0053] Prepare tube blanks;

[0054] The two ends of the tube blank are narrowed to form a narrowed tube;

[0055] The constricted tube is hydraulically formed to create the bridge section 5 located in the middle.

[0056] Specifically, in this embodiment, in order to reduce the cracking that may occur during the hydraulic forming process, the hydraulic forming process includes three stages: the first hydraulic forming stage, the second hydraulic forming stage, and the third hydraulic forming stage. Accordingly, three sets of molds will be set up.

[0057] In the first stage of hydroforming, the corresponding mold cavity is the initial cavity, which is a relatively regular geometric shape. The middle part of the product after hydroforming is roughly cylindrical, that is, hydroforming is only performed roughly in the middle of the constricted tube to make it expand outward. The forming volume is the largest in this stage. The regular cavity design is conducive to the hydroforming process and avoids cracking problems caused by irregular shapes when the forming volume is large.

[0058] In the second hydraulic forming stage, the corresponding mold cavity is an intermediate cavity, and its cavity structure is close to the shape of the bridge portion 5. The position corresponding to the bulge portion 51 is still a relatively regular shape.

[0059] In the third hydroforming stage, the corresponding mold cavity is the final cavity, and its cavity structure is exactly the same as the outer contour of the bridge section 5. In the third hydroforming stage, the part produced in the second hydroforming stage is fine-tuned to make it into... Figure 2 The bridge housing 100 shown.

[0060] Therefore, the hydroforming process in this embodiment, through multi-stage hydroforming, can avoid cracking problems that may occur with one-time forming of the constricted tube due to excessive forming volume or irregular deformation. It is understood that, according to simulation or experimental verification, for bridge housings 100 of different sizes and structural forms, the aforementioned hydroforming stages can be one, two, or more than three. When manufacturing through two or more hydroforming stages, the structure of the cavity in each stage can also be adjusted to further ensure the smooth hydroforming of the irregularly shaped bridge housing 5 through a phased, step-by-step forming method.

[0061] The integral axle housing 100 formed by hydroforming in the above embodiments has the advantage of flexible development. Through the design of the bulge 51 of the axle housing 5, both the bulge and clearance functions are achieved, and the hydroforming process can smoothly produce the required product. Compared to the welding methods mentioned in the background art, the axle housing 100 formed in this embodiment obviously reduces the waste of welding processes and eliminates fatigue cracking caused by welding defects. Moreover, compared to axle housings formed by welding and casting, the axle housing 100 in this embodiment has a significant weight reduction effect. Compared to existing welded and stamped axle housings, the axle housing 100 made by hydroforming in this embodiment weighs only 7.4 kg, a weight reduction of up to 10.8%, demonstrating a significant lightweighting effect. Furthermore, from the perspective of product characteristics, the dimensions of the axle housing 5 remain unchanged, the length of the sleeve can be varied according to the vehicle width, and the wall thickness of the axle housing 100 can be adjusted according to the vehicle load. That is, the thickness of the blank can be adjusted according to the load requirements, thereby changing the thickness of the axle housing 100. Based on the characteristics of the hydraulic bulging process, the thickness of the bridge housing 100 can be changed simply by adjusting the plug in the bulging mold, and the length of the bridge housing 100 can be changed simply by replacing the inserts at both ends of the mold.

[0062] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A drive axle housing, characterized in that, The bridge housing includes a bridge envelope portion located in the middle and sleeve portions extending from the bridge envelope portion to both sides. The sleeve portions and the bridge envelope portion on both sides are integrally hydraulically formed. One end of the bridge envelope portion is a bulge portion, and the opposite end is provided with an installation port for the main reducer to be inserted. The wall of the bulge portion is generally a spherical wall, which is a hemispherical wall or a small hemispherical wall, and the spherical wall is partially provided with a flat portion and an arc-shaped portion. The bulge includes a first clearance position corresponding to a secondary driven gear located within the axle housing. The first clearance position is offset relative to the center of the axle housing and disposed on a first side of the bulge. An arcuate portion is provided between the first clearance position and the root of the first side of the bulge, the length of which is shorter than the design profile length of the corresponding spherical shape. The bulge also includes a second side opposite to the first side. A planar portion is provided between the first clearance position and the root of the second side of the bulge, the length of which is shorter than the design profile length of the corresponding spherical shape.

2. The axle housing of the drive axle according to claim 1, characterized in that, The flat part is provided with an oil filling hole.

3. The axle housing of the drive axle according to any one of claims 1-2, characterized in that, The casing section, from its end toward the bridge section, sequentially includes a round pipe section, a round-square pipe transition section, a square pipe section, and a casing-bridge transition section.

4. The axle housing of the drive axle according to claim 3, characterized in that, The upper part of the round-square tube transition section is used to connect the spring seat, and the lower part is used to connect the lower longitudinal arm bracket.

5. A vehicle, characterized in that, The axle housing includes the drive axle as described in any one of claims 1-4.

6. A hydroforming process for an axle housing, used to process the axle housing of the drive axle according to any one of claims 1-4, characterized in that, Includes the following steps: Prepare tube blanks; The two ends of the tube blank are narrowed to form a narrowed tube; The constricted tube is hydraulically formed to create a bridge section located in the middle.

7. The hydroforming process for the bridge housing according to claim 6, characterized in that, During hydroforming, a round-square tube transition section, a square transition section, and a sleeve bridge transition section are formed, which are sequentially connected to the constricted end of the constricted tube.

8. The hydroforming process for the bridge housing according to claim 7, characterized in that, The hydroforming process includes at least two hydroforming stages. In the first hydroforming stage, the cavity of the corresponding mold is cylindrical corresponding to the position of the bridge section, so as to regularly shape the middle part of the constricted tube. In the final hydraulic forming stage, the cavity of the corresponding mold corresponds to the position of the bridge section and the outer contour of the bridge section.

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