The present invention relates to a mechanical joint assembly, in particular a swivel assembly. Furthermore, the present invention relates to a method of assembling such an assembly. In the aviation industry, it is known to use a mechanical joint assembly for preventing two members, such as a rod and a structural part, from moving in relative translation, while nevertheless allowing those members to move relative to each other in rotation. A mechanical joint assembly serves in particular to compensate locally for the deformation and/or movement of an aircraft in operation.
A prior art mechanical joint assembly, in particular a swivel assembly, generally comprises an inner ring such as a ball core in which a shaft is mounted, an intermediate member defining a housing in which the ball core swivels, and an outer body defining a chamber for retaining the intermediate member. The chamber is a cavity that is configured to receive the intermediate member. In addition, the chamber is configured to allow movement in translation along a direction that is orthogonal to the axis of the joint. This movement gives a shaft mounted in the swivel assembly a degree of freedom in addition to those authorized by the swivel connection. In order to allow this movement, the chamber of the prior art mechanical joint assembly has two surfaces that are plane and parallel and that extend on either side of the intermediate member. The intermediate member presents two surfaces that are plane and complementary to the plane surfaces of the chamber, thereby allowing the intermediate member to move in translation relative to the outer body.
Nevertheless, the plane bearing connections formed between these respective plane surfaces present relatively limited capacity to accommodate contact. The swivel assembly must present little thickness and therefore plane surfaces that are relatively limited. In addition, with machining of ordinary quality, the respective plane surfaces of the outer body and of the intermediate member give rise to plane bearing connections that are not perfect, since these planes come into contact only along two lines. That is why contact pressures between the outer body and the intermediate member are relatively high, thereby reducing the lifetime of the swivel assembly. In addition, such plane bearing connections present relatively limited capacity to retain lubricant. In addition, such plane bearing connections do not prevent the intermediate member from moving in translation relative to the outer body along the axis of the joint, such that a swivel assembly of the prior art also needs to include a blocking component to retain the intermediate member in the chamber along the axis of the joint. Such a blocking member increases overall size, cost, and difficulty of assembling such a swivel assembly.
A particular object of the present invention is to remedy those drawbacks by proposing a compact swivel assembly that has a long lifetime and that is relatively simple to assemble.
To this end, the present invention provides a mechanical joint assembly, in particular a swivel assembly, comprising:
According to characteristics of the present invention that are advantageous but optional, whether taken in isolation or in any technically feasible combination:
Furthermore, the present invention provides a method of assembling a mechanical joint assembly as defined above, in particular a swivel assembly, the method comprising the following steps:
By means of the invention, the intermediate member is retained in the retaining chamber, contact pressures are relatively low, ability to retain lubricant is large, and the overall size of the swivel assembly is limited, and it is relatively simple to assemble.
The present invention can be well understood and its advantages appear further in the light of the following description given purely by way of non-limiting example and made with reference to the accompanying drawings, in which:
The swivel assembly 1 also includes a resilient ring 4 received in a groove 10.4 that is formed in the inside surface 10.5 of the core 10. The resilient ring 4 contributes to assembling a shaft (not shown) in the swivel assembly 1.
As shown in
The insert 20 has a bearing inside surface 20.1 that is complementary in shape to the joint outside surface 10.1. The bearing inside surface 20.1 is thus in the form of a truncated sphere. The axis of revolution of the bearing inside surface 20.1 defines an axis Z20 of the joint. Since the joint outside surface 10.1 and the bearing inside surface 20.1 are of complementary shape, the insert 20 can receive the core 10. The angular difference between the swivel axis Z10 and the axis Z20 of the joint corresponds to a swivel angle that varies when the core 10 turns in the housing formed by the insert 20. In the example of
In the present application, the adjectives “inner” and “inside” designate an entity, e.g. a circuit, that is closer to or that faces towards the axis Z20 of the joint. Conversely, the adjectives “outer” and “outside” qualify an entity, e.g. a surface, that is remote from or that faces away from the axis Z20 of the joint.
As shown in
Furthermore, the insert 20 defines two first surfaces 20.5 and 20.6 that are formed by convex cylinder portions. Specifically, the first peripherals 20.5 and 20.6 are two portions of a common first circular cylinder, such that they have a first axis X25 as a common axis of revolution. As shown in
In similar manner, the body 30 defines two second surfaces 30.5 and 30.6 that are in the form of concave cylinder portions. Specifically, the second surfaces 30.5 and 30.6 are portions of a common second circular cylinder, such that they have a second axis X35 as their common axis of revolution. The second surfaces 30.5 and 30.6 extend over two opposite sides of the chamber 30.1. The second surfaces are symmetrical about the center of the chamber 30.1 (center not shown).
The diameter D20 of the circular base of the first cylinder is substantially equal to the diameter D30 of the circular base of the second cylinder. Specifically, the diameters O20 and D30 are identical. In other words, when the swivel assembly 1 is in the assembled state, each first surface 20.5 or 20.6 coincides substantially with a respective second surface 30.5 or 30.6. In the example of
Thus, the first surfaces 20.5 and 20.6 co-operate with the second surfaces 30.5 and 30.6, thereby enabling the insert 20 to rotate relative to the body 30 about the first axis X25, since the first axis X25 coincides with the second axis X35 when the swivel assembly 1 is in the assembled state. In other words, the insert 20 pivots in the chamber 30.1.
Each first surface 20.5 or 20.6 is configured to co-operate with a respective second surface 30.5 or 30.6 in such a manner that when the insert 20 is mounted in the chamber 30.1, the first surfaces 20.5 and 20.6 and the second surfaces 30.5 and 30.6 enable the insert 20 to rotate relative to the body 30, but prevent the insert 20 from moving in translation parallel to the axis Z20 of the joint or parallel to an orthogonal axis Y20 that is orthogonal to the axis Z20 of the joint and to the second axis of revolution X35.
The amplitude of this rotation is limited because of the overlap between the insert 20 and the body 30, i.e. because of the respective thickness E20 and E30 of the insert 20 and of the body 30 as measured along the axis Z20 of the joint. In operation, a shaft not shown) is mounted in the swivel assembly 1. Such a shaft has little freedom of angular movement, thereby limiting rotation of the insert 20 within the body 30 and thus preventing the insert from escaping.
Furthermore, when the insert 20 is mounted in the chamber 30.1, co-operation between the first surfaces 20.5 and 20.6 with the second surfaces 30.5 and 30.6 prevents the insert 20 from moving in translation parallel to the axis Z20 of the joint or parallel to an axis Y20 that is orthogonal to the axis Z20 of the joint and to the second axis X35. In other words, when the first surfaces 20.5 and 20.6 co-operate respectively with the second surfaces 30.5 and 30.6, it is possible to transmit forces parallel to the axis Y20.
The dimensions of the chamber 30.1 measured along the second axis X35 are greater than the dimensions of the insert 20 measured along the first axis X25. Thus, when the insert 20 is mounted in the chamber 30.1, the first surfaces 20.5 and 20.6 and the second surfaces 30.5 and 30.6 co-operate so as to allow the insert 20 to move in translation relative to the body 30. In other words, the insert 20 slides in the body 30 by the first surfaces 20.5 and 20.6 sliding on the second surfaces 30.5 and 30.6. In the embodiment shown in
The ratio of the width L25 of the insert 20, i.e. its greatest dimension measured along the first axis X25 to the amplitude of the movement in translation of the insert 20 relative to the body 30 lies in the range 5 to 20. Such a ratio gives the insert 20 an acceptable degree of freedom.
As shown in
A cross-section of the chamber 30.1 relative to the axis Z20 of the joint is rectangular in shape having circularly rounded corners. In addition, the chamber 30.1 presents two lateral abutment surfaces 30.7 and 30.8 that are of cylindrical shape and complementary to the shapes of the third surfaces 20.7 and 20.8, respectively. While moving in translation parallel to the first axis X25, the insert 20 comes into abutment against the lateral abutment surface 30.7 or 30.8.
Furthermore, the ratio of the greatest dimension L25 of the insert 20 measured along the first axis X25 divided by the width L20.5 or L20.6 measured along the first axis X25 is equal to 3.1. In practice, this ratio lies in the range 2.5 to 3.5. Such a ratio makes it possible to avoid jamming when the insert 20 is moved in translation in the chamber 30.1.
In the second step shown in
In a third step shown in
In a fourth step, shown in
In a fourth step shown in
The reduction in contact pressure comes firstly from the increase in the capacity for accommodating contact between the insert and the body, and secondly from the increase in the contact area between the insert and the body.
In a variant that is not shown, the faces of the swivel assembly and/or of one or the other of its components are not plane, but may for example be bulging.
Number | Date | Country | Kind |
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09 53945 | Jun 2009 | FR | national |