Power transmission device

Abstract

The present invention relates to an annular power transmission element 22 having a longitudinal axis X, comprising a first annular part 26a, a second annular part 26b including a torque transmission device 46a, and a third annular part 26c which are joined to one another. The first annular part 26a and the third annular part 26c are made of a first metallic material, and the second annular part 26b is made of a second metallic material having a density greater than that of the first metallic material. The second annular part 26b is longitudinally locked between the first annular part 26a and the third annular part 26c and radially locked to the first annular part 26a, and the first annular part 26a contacts and is welded to the third annular part 26c.

Description

Technical Field

[0001] The present invention relates to a power transmission element, and more particularly to a power transmission element made of two materials. Background Art

[0002] Figure 1 There is shown a known type of annular power transmission element 10 made of a single material, such as steel. It includes a tubular barrel 12 having an inner groove 14 for connecting the power transmission element to a shaft having a mating groove. An annular web 16 radially connects the barrel to a radially outer annular member having annular teeth 18. Of course, the teeth 18 and the splines 14 can be part of two separate power transmission elements 10.

[0003] In operation, the splines 14 and the teeth 18 provide a power transmission that requires these components to be made of a material with high mechanical strength, which explains why steel power transmission elements 10 are usually manufactured. However, such power transmission elements 10 are relatively heavy.

[0004] Therefore, it has been proposed to build the power transmission element 10 from two materials. Figure 2 The shown power transmission element 10 is a gear, where it includes an annular web 16 made of aluminum and teeth 18 made of steel. The annular web 16 and the teeth 18 are rigidly attached to each other by a threaded connection 20.

[0005] If the principle of implementing a power transmission element with two materials is interesting, the proposed design has problems because it requires the integration of threaded components. This technique is not advisable because it requires machining for centering the barrel 12 with the web 16 to achieve its assembly and ensure its coaxiality. These centering machinings are intended to produce a radially outer annular surface of the barrel 12 and a radially inner annular surface on the web 16, and the radially outer annular surface of the barrel 12 and the radially inner surface of the web 16 are intended to cooperate together to form the centering of the web 16 on the barrel 12.

[0006] The machining operations also include drilling holes distributed circumferentially through the web 16 and the teeth 18. These holes cross the fixing screws 20. Such a component with multiple basic fixing points has reliability problems that can lead to the disassembly of the web 16 and the teeth 18.

[0007] In addition, the assembly and maintenance of the power transmission element require traceability of its component parts, namely the barrel 12, the web 16, the teeth 18, and the fixing screws 20. This traceability requires a large amount of expensive logistics.

[0008] The present invention aims to propose a solution for constructing an annular power transmission element to overcome all or part of the above-mentioned drawbacks. Summary of the Invention

[0009] This document relates to a power transmission annular element having a longitudinal axis, which comprises a first annular part, a second annular part including a torque transmission device, and a third annular part integrated with each other, wherein the first annular part and the third annular part are made of a first metallic material, the second annular part is made of a second metallic material having a density greater than the density of the first metallic material, the second annular part is longitudinally locked between the first annular part and the third annular part, and is radially locked to at least one of the first annular part and the third annular part.

[0010] The first annular part can be in contact with the third annular part. The first annular part can be directly attached to the third annular part. The first annular part can be welded to the third annular part.

[0011] The power transmission unit consists of three parts that are structurally different from each other. Only the second annular part containing the torque transmission device needs to be made of a material with a higher density, while the first part and the third part are made of materials with a lower density, which can reduce the mass of the power transmission element. The first annular part and the third annular part thus do not have a torque transmission device.

[0012] In addition, the locking of the second annular part to the first annular part and the third annular part is formed by the axial abutment of the second annular part on the first and third annular parts. These axial abutments prevent the axial displacement of the second part, thus forming a rigid assembly.

[0013] The welding of the first part and the third part can be friction stir welding. This type of welding allows for a rigid connection between two metal parts without the need for any filler material.

[0014] This welding technique makes it possible to weld together metal materials that are considered non-weldable using traditional welding techniques, which is the case for new aluminum alloys. More specifically, friction stir welding is a solid-phase welding process that takes place at a temperature below the melting temperature of the material and thus avoids the formation of defects associated with traditional welding. For example, defects related to poor solidification of the molten pool may be the formation of pores or cracks.

[0015] Friction stir welding is considered to be the only process capable of welding the latest generation of aerospace aluminum alloys.

[0016] Finally, friction stir welding produces welded joints with high mechanical properties, which are generally superior to those obtained by traditional fusion welding techniques.

[0017] By positive fitting with at least one of the first component and the third component, the second annular component can be adapted to rotationally lock the second component with the first and second annular components.

[0018] The presence of a positive fitting between the second annular component and the first and / or third annular components can thus prevent any rotation of the second annular component and lock it to the first and third annular components.

[0019] The third component may include an annular component that is in radial annular contact with the first annular component and carries a plurality of fingers that engage the housing of the second annular component.

[0020] The positive fitting may include engaging the fingers of the third annular component in openings formed in the housing of the second annular component.

[0021] The first annular component may include an annular shoulder, the second annular component is longitudinally applied on the annular shoulder, and the third annular component is longitudinally arranged opposite the shoulder with respect to the second annular component.

[0022] In a particular embodiment, the fingers may pass through the second annular component, and the ends of the fingers are welded to the annular shoulder.

[0023] The weld at the contact between the end of the finger and the shoulder of the first annular component and the weld between the walls at the radial contact between the first annular component and the third annular component strengthen the connection between the first and third annular components that holds the second annular component in place.

[0024] The finger welding is preferably friction stir welding, more specifically, transparent welding, which includes inserting a rotating mandrel through the first component until it contacts the end of the finger, thereby welding the first annular component with at least the end of the finger of the third annular component.

[0025] The torque transmission device may be radially outwardly directed, and the third annular component surrounds and is welded to the cylindrical surface of the first annular component.

[0026] The torque transmission device can thus be a tooth that radially extends from the end of the power transmission element.

[0027] The third annular component may include an annular edge that is welded to the annular edge of the first annular component.

[0028] The arrangement and welding between the first annular member and the third annular member are carried out in such a way that the annular edges of the first annular member and the third annular member form surface continuity without any steps. Preferably, the welding can be of the edge-to-edge type.

[0029] The torque transmission device can be radially inwardly directed, and the third annular member is mounted inside and welded to the cylindrical surface of the first member.

[0030] The torque transmission device can thus be a spline extending radially inwardly from the radially inner surface of the cylinder.

[0031] In a practical embodiment, the first metal material can be aluminum alloy. The second metal material can be steel. The indication that the first annular member and the third annular member are made of the first metal material does not mean that the material is exactly the same for the first annular member and the third annular member.

[0032] The present invention will be better understood when reading the following description given as a non-limiting example with reference to the accompanying drawings, and other details, features and advantages of the present invention will be apparent. Description of the Drawings

[0033] - The above-described Figure 1 is a perspective view of a first power transmission element of the prior art,

[0034] - The above-described Figure 2 is a front view of a second power transmission element of the prior art;

[0035] - Figure 3A is a semi-sectional view of a power transmission element according to the present invention along a cutting plane including the axis of the transmission element and not passing through the fingers of the third annular member;

[0036] - Figure 3B is a semi-view of the power transmission element shown along a cutting plane including the axis of the power transmission element and passing through one of the fingers of the third member Figure 3A ;

[0037] - Figure 4A is a front view of the third member of the power transmission element according to the first embodiment of the present invention;

[0038] - Figure 4B is Figure 4A a side view of the third member;

[0039] - Figure 5 is a sectional view of a power transmission element according to the second embodiment of the present invention,

[0040] - Figure 6 A perspective view of a third component of a power transmission element according to a second embodiment of the present invention;

[0041] - Figure 7 A cross-section showing a welding path according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0042] The annular power transmission elements 22, 24 of two embodiments of the present invention will now be described. Figure 3A , 3B A first embodiment of the power transmission element 22 is shown in FIGS. 4A and 4B. Figure 5 , 6 A second embodiment of the power transmission element 24 is illustrated in FIGS. 7.

[0043] In each embodiment, the annular power transmission elements 22, 24 include three annular components coaxial along a longitudinal axis X, a first annular component 26a, 28a, a second annular component 26b, 28b, and a third annular component 26c, 28c. In each embodiment, the first component 26a, 28a and the third annular component 26c, 28c are made of a metal material having a density lower than that of the second annular component 26b, 28b. Specifically, the first component 26a, 28a and the third annular component 26c, 28c are made of aluminum alloy, and the second annular component 26b, 28b is made of steel.

[0044] In the first embodiment, the first annular component 26a includes a tubular cylinder 12 and an annular web 16. The annular web 16 includes a first substantially radially inner annular wall 30 that is radially connected to an annular redundant portion 32 at its ends in the axial direction. A second outer annular wall 34 extends radially outward from a radially outer annular surface 36 of the annular redundant portion 32. The radially outer annular surface 36 of the redundant portion 32 is substantially cylindrical. The second radially annular wall 34 includes a radially annular surface 38 that forms an annular shoulder, the advantages of which will be presented in the following description. It can be seen that the second outer radially annular wall 34 includes a radially outer annular surface 40 that is substantially cylindrical and mates with the second annular component 26b, which will also be presented more clearly later. Therefore, it can be understood that the web 16 of the first annular component 26a includes a first radially annular wall 30, an annular redundant portion 32, and a second radially annular wall 34.

[0045] The second annular part 26b has a T-shaped cross-section along a cutting plane including the longitudinal axis. The second annular part includes a radial annular wall 42 that is connected at its radially outer end to a cylindrical wall 44 that carries a first torque transmission device 46a. The first torque transmission device 46a can be an annular tooth 18 that is designed to engage the teeth of another part. The cylindrical wall 44 includes a radially inner cylindrical face 48 that is applied to the cylindrical face 40 of a second radial annular wall 34 of the web 16 of the first annular part 26a. The radial annular wall 42 of the second annular part 26b includes a first radial annular face 50 and a second radial annular face 52. The first radial annular face 50 is applied to the radial annular face 38 that forms the annular shoulder of the first part 26a. The radial annular wall 42 of the second annular part 26b includes an inner cylindrical face 54 at its radially inner end, and the inner cylindrical face 54 is applied to the cylindrical face 36 of the redundant portion 32 of the first annular part 26a. Additionally, the radial annular wall 42 includes a plurality of longitudinally traversing housings 56.

[0046] In Figures 3A to 4B the particular case shown, the housings 56 are notches and open radially inwards. They are preferably evenly circumferentially distributed around the longitudinal axis X.

[0047] The radial adjacency between the first annular part 26a and the second annular part 26b constitutes a device for centering the second annular part 26b relative to the first annular part 26a.

[0048] The third annular part 26c includes a ring 58 that carries a plurality of fingers 60. The fingers 60 are circumferentially distributed around the longitudinal axis X and project on a first radial annular face 62 of the ring 58. Once the fingers 60 of the third annular part 26c have been inserted into the annular housing 58, the annular housing abuts against the radial annular wall 38 that forms the shoulder of the first annular part 26a. When the fingers 60 are inserted into the housing 58, the first radial annular face 62 that carries the fingers 60 will be applied to the second radial annular face 52 of the radial annular wall 42 of the second annular part 26b. The ring 58 of the third annular part 26c also includes a radially inner cylindrical face 64 and a radially outer cylindrical face 66. Once the fingers 60 have been inserted into the housing 58, the inner cylindrical face 64 of the third annular part 26c is radially applied to the cylindrical face 36 of the redundant portion 32 of the first annular part 26a, and the outer cylindrical face 66 is radially applied to the inner cylindrical face 48 of the cylindrical wall 44 of the second annular part 26b.

[0049] The third annular member 26c includes a second radial annular face 68 that is axially opposite to the first radial annular face 62 of the carrier finger 60. The second radial annular face 68 of the third annular member 26c is flush with the axial end 70 of the redundant portion 32 of the first member 26a. Preferably, the end 70 of the redundant portion 32 is axially opposite to the second radial wall 34 of the first annular member 26a. The second radial annular face 68 of the third annular member 26c and the axial end 70 of the redundant portion 32 form a surface continuity without any step.

[0050] The first and third annular members 26a, 26c are welded together edge to edge at the radial adjacency between the inner cylindrical face 64 of the third member 26c and the cylindrical face of the redundant portion 32 of the first annular member 26a.

[0051] This edge-to-edge welding is friction stir welding. This welding means that there is no weld seam on the coplanar plane of the first and third annular members 26a, 26c. The edge-to-edge welding of the first and third annular members 26a, 26c thus prevents any axial displacement of the second annular member 26b axially adjacent thereto.

[0052] Each of the fingers 60 of the third annular member 26c axially adjacent to the radial annular face 38 forming the shoulder of the first annular member 26a has a radial face 72 that is welded to the radial annular face 38 forming the shoulder of the first annular member 26a.

[0053] This welding is preferably friction stir welding, which consists of inserting a mandrel through the first annular member 26a until it contacts the end 72 of the finger 60, thereby welding them together.

[0054] Once the first and third annular members 26a, 26c have been welded, the insertion of the fingers 60 of the third member 26c into the housing 58 of the second member 26b prevents any rotation of the second member 26b relative to the first and third members 26a, 26c along the longitudinal axis X.

[0055] In Figures 3A to 4B In the particular case shown, the second annular member 26b has three housings 58, and the third annular member 26c has three fingers 60, each of the fingers 60 cooperating with one of the housings 58.

[0056] In the second embodiment, the power transmission element 24 includes a cylinder 12 formed by a first annular member 28a, a second annular member 28b, and a third annular member 28c.

[0057] The first annular member 28a includes a tubular wall 74. The tubular wall has an inner cylindrical surface 76. The inner cylindrical surface 76 includes a first inner cylindrical surface 76a and a second inner cylindrical surface 76b. The first and second inner cylindrical surfaces 76a, 76b are connected to each other by a radial annular wall 78, forming a shoulder with the second inner cylindrical wall 76b, the advantages of which will be presented in the following description.

[0058] The second annular member 28b includes a tubular wall 80, the inner cylindrical surface of which has a second torque transmission device 46b. The second torque transmission device 46b can be a spline 14 designed to cooperate with the corresponding splines of a shaft. The tubular wall 80 includes a radially outer cylindrical surface 84, which is applied to the second cylindrical surface 76b of the first annular part 28a. The second annular member 28b also includes a first radial annular surface 86, which is applied to the radial annular wall 78 forming the shoulder of the first member 28a. The second annular member 28b includes a second radial annular surface 88 axially opposite to the first radial annular surface 86. The second radial annular surface 88 has a plurality of axially extending blind housings 90. The blind housings 90 open radially to the outside.

[0059] The third annular member 28c includes a ring 92 carrying a plurality of fingers 94, which are circumferentially distributed around the longitudinal axis X and project on the radial annular surface 96 of the ring 92. The ring 92 also includes a radially inner cylindrical surface 98 and a radially outer cylindrical surface 100. Each of the fingers 94 has an outer cylindrical surface 102, which axially extends in the extension of the outer cylindrical surface 100 of the ring 92 of the third annular member 28c.

[0060] Once the fingers 94 of the third annular part 28c have been inserted into the blind housings 90 of the second annular part 28b, the radial annular surface 96 carrying the fingers 94 axially abuts on the second radial annular surface 88 of the second annular part 28b provided with the blind housings 90. The outer cylindrical surface 102 of the fingers 94 and the outer cylindrical surface 100 of the ring 92 of the third annular wall 28c annularly and radially abut on the second inner cylindrical surface 76b of the first annular part 28a.

[0061] The fingers 94 of the third annular part 28c and the outer cylindrical surfaces 100, 102 of the ring 92 are welded to the second inner cylindrical surface 76b of the first annular part 28a. This welding is preferably transparent friction stir welding.

[0062] The mandrel thus preferably adapts to the periphery 104 of the radially adjacent area between the first and third annular members 28a, 28c, as Figure 7 shown.

[0063] The welding of the first and third annular members 28a, 28c thus prevents the axial displacement of the second annular member 28b axially adjacent thereto.

[0064] The presence of the fingers 94 of the third member 28c inserted into the housing 90 of the second member 28b prevents any rotation of the second member 28b relative to the first and third annular members 28a, 28c along the longitudinal axis X.

[0065] In an embodiment not shown in the figures, the power transmission elements 22, 24 may include a first torque transmission device 46a according to the first embodiment and a second torque transmission device 46b according to the second embodiment.

Claims

1. An annular power transmission element having a longitudinal axis, comprising a first annular part, a second annular part including torque transmission means, and a third annular part which are joined together, wherein the first annular part and the third annular part are made of a first type of metallic material, the second annular part is made of a second type of metallic material having a density greater than that of the first type of metallic material, the second annular part is longitudinally locked between the first annular part and the third annular part and is radially locked to at least one of the first annular part and the third annular part, the second annular part is in positive fit with at least one of the first annular part and the third annular part for rotationally locking the second annular part to the first annular part and the third annular part, and the third annular part includes an annular portion which is in radial annular contact with the first annular part and carries fingers which engage with the housing of the second annular part.

2. The element according to claim 1, wherein, the first annular part is in contact with the third annular part and is directly connected thereto.

3. The element according to claim 2, wherein, the first annular part is welded to the third annular part.

4. The element according to claim 3, wherein, the welding of the first annular part to the third annular part is friction stir welding.

5. The element according to any one of claims 1 to 4, wherein, the first annular part includes an annular shoulder, the second annular part is longitudinally applied to the annular shoulder, and the third annular part is longitudinally arranged opposite the shoulder with respect to the second annular part.

6. The element according to claim 5, wherein, the fingers pass through the second annular part, and the ends of the fingers are welded to the annular shoulder.

7. The element according to any one of claims 1 to 4, wherein, the torque transmission means is radially outwardly directed, and the third annular part surrounds and is welded to the cylindrical surface of the first annular part.

8. The element according to claim 7, wherein, the third annular part includes an inner annular edge which is welded to the outer annular edge of the first annular part.

9. The element according to any one of claims 1 to 4, wherein, the torque transmission means is radially inwardly directed, and the third annular part is mounted within and welded to the cylindrical surface of the first annular part.

10. The element according to any one of claims 1 to 4, characterized in that, the first type of metallic material is aluminium alloy.

11. The element according to any one of claims 1 to 4, characterized in that, the second type of metallic material is steel.

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