Patent Application
20230080669
The present invention relates to the technical field of connecting rods, shafts and arms intended to be positioned between two fixed or mobile members, the length of which can be adjusted in order to fit, and relates in particular to a length-adjustable connecting rod provided with a resisting torque device.
Such rods are used, for example, between a fixed and a mobile member such as a shutter mechanism. Due to manufacturing and assembly tolerances of the individual components, the distance between them can fluctuate by several millimeters. In order to fit the connecting rod, it is necessary to adjust its length. This is achieved by means of length-adjustable connecting rods comprising a connecting element such as a fork, a ball joint or a metal clevis and a tube that cooperates with a threaded device to change the length of the connecting rod when it is fitted. The length-adjustable connecting rod may also comprise a rotational braking device that acts on the rotational movement to apply a specific locking force between the fork and the tube and thus prevent an unintentional change in length of the connecting rod when it is not stressed to deliberately vary its length, as in the case of stresses due to vibrations, fatigue cycle in traction, compression, bending, thermal gradient up to 140° C.
For example, WO2006042750 describes a tension-compression bar that comprises a fork and a tube, the rotation of the fork around the tube can be locked by a locking device that comprises a partial ring with a locking nose and a ring gear.
The disadvantage of such a device is that it requires an intermediate part such as a sleeve placed between the fork and the tube and comprising two threads, a first thread located on the external wall of the sleeve for connecting the tube of the connecting rod and a second thread located on the internal wall for connecting the fork. When mounting the connecting rod, the first thread must be kept locked because only the second thread is involved in adjusting the length of the connecting rod. This double thread makes the manufacture and assembly of the parts that make up the connecting rod more complex. In addition, if the locking of the first thread is to be secured, an additional step must be performed, such as gluing the thread.
On the other hand, the connecting rod locking device described in WO2006042750 acts on the torque between the fork and the tube by virtue of the locking nose of the partial ring that fits into a space in the ring gear. The partial ring is connected to the fork by means of an offset bolt and a connecting element that links the partial ring to the bolt. These two fasteners are prominent with respect to the outer circumference of the connecting rod. Also the ends of the partial ring are directed outwardly and are prominent. The positioning of these elements can injure the operator who handles and sets up the connecting rod.
In addition, the fact that the partial ring is fixed to the connecting rod by means of a fastener offset from the plane in which the clamping force is exerted creates a clamping torque between the fork and the tube that varies according to the position of the fork in the tube. In addition, the locking nose of the partial ring is not aligned, in the direction of the axis of rotation, with the connecting element, which means that the tightening torque is not identical depending on whether the operator turns the connecting rod in one direction or the other. Therefore, the torque between the fork and the tube also varies depending on the direction of adjustment of the fork with respect to the tube.
Similarly, the connecting rod described in WO2011057627 comprises two threads, one of which allows the length of the connecting rod to be changed. This thread comprises a first thread located on the outside of the fork that cooperates with a second thread located on the inside of a connecting piece. A spring presses two locking elements together in the longitudinal direction of the connecting rod. As the spring is supported with its ends between the fork and the connecting piece, it also presses the external thread against the internal thread of the connecting rod, which allows the length of the connecting rod to be changed. One of the disadvantages of this connecting rod is that the torque depends on the friction between the locking elements but also on the friction between the two threads. Now the friction between the two threads depends on the surface in contact with the threads, this surface is lowest when the fork is completely extended and greatest when it is completely retracted. As a result, the torque between the fork and the tube varies depending on the position of the fork in the tube.
Therefore, the purpose of the invention is to provide a length-adjustable connecting rod with a resisting torque device that overcomes the above-mentioned disadvantages and, in particular, that comprises a single thread per end and provides a constant resisting torque, regardless of the position of the fork in relation to the tube.
Another purpose of the invention is to provide a simple and economical manufacturing method for making length-adjustable connecting rods whose resisting torque device provides a constant resisting torque regardless of the position of the fork relative to the tube.
The object of the invention is therefore a length-adjustable connecting rod having a longitudinal axis, comprising a connecting-rod shank provided with at least one internal thread, at least one connecting element comprising an external thread cooperating with the internal thread of the connecting-rod shank, the screwing or unscrewing of the connecting-rod shank with respect to the connecting element allowing the length of the connecting rod to be adjusted, and at least one resisting torque device between the connecting-rod shank and the connecting element, the resisting torque device comprising at least one pressing element and a bearing element, the pressing element exerting a force on the bearing element that opposes a resistance to the rotational movement of the connecting-rod shank with respect to the said connecting element. The connecting rod is characterized in that the bearing element is integral with the connecting element and the pressing element is integral with the connecting-rod shank and in that the force exerted by the pressing element on the bearing element is in a transverse direction and perpendicular to the longitudinal axis of the connecting rod.
Another object of the invention is a method for making and assembling a connecting rod, comprising the following steps:
a) a connecting-rod shank consisting of an end cap, a threaded insert and a tube is manufactured and assembled in a single injection-molding step,
b) a connecting element is machined in one piece, preferably from a metallic material, with a first free end and a second end having a locking device,
c) a notched ring is securely mounted on the connecting element,
d) a gasket is placed in a groove provided on the connecting element at the end of the notched ring,
e) at least one ball plunger or leaf spring is placed in a receptacle provided for this purpose in the wall thickness of the end cap,
f) the connecting element is inserted and screwed into the connecting-rod shank by cooperation of the threads and until the two blades at the opposite end of the free end of the connecting element come to rest with their locking element in the form of a radially outwardly projecting bead against the end of the threaded insert, the locking device thereby being automatically inserted.
The purposes, objects and features of the invention will become clearer upon reading the following description made with reference to the drawings wherein:
The embodiment described and illustrated in the figures is therefore the preferred embodiment when the bearing device and the fork are not made of the same material, for example for an aluminum fork and a thermoplastic bearing element. This method reduces the risk of galvanic corrosion. In this embodiment, the bearing element is integrally mounted on the connecting element by virtue of means for immobilizing it on the connecting element. These means are described in the following description.
The free end of the fork 10 extends into a central cylindrical portion 101 that supports the bearing element of the resisting torque device.
The central cylindrical portion 101 is provided with a flange 102 located on the outer face of the cylindrical portion 101 on the side of the free end of the fork.
The flange is circular and located in a plane perpendicular to the axis 5 and its external diameter is greater than the external diameter of the cylindrical part by 0.1 mm to 0.5 mm. The flange has two opposite faces, a flat face perpendicular to the axis 5 and a truncated cone-shaped face. The flat face is located on the side of the free end of the fork while the truncated cone-shaped face is directed in the opposite direction, i.e. towards the center of the connecting rod.
At the opposite end of the free end of the fork, the cylindrical part is extended by a groove 105 adapted to house a gasket 115, a thread 106 and two blades 107 each provided on their external face and at their end with a locking element in the form of a bead 108 projecting radially outwardly. The central cylindrical portion 101 comprises at least one slot 103 located on its outer surface and parallel to the axis 5 extending from the groove 105 toward the middle portion of the cylindrical portion. According to another embodiment, the central cylindrical portion 101 comprises a second slot also located on its outer surface, parallel and preferably diametrically opposite to the first slot. The gasket 115 guarantees the seal between the tube and the fork against galvanic corrosion.
The bearing element of the resistant torque device and integral with the fork is a toothing 331 comprising a set of teeth. Even in the case where the bearing element is machined directly with the fork, the toothing 331 is preferably straight, i.e., the teeth of the toothing 331 are evenly distributed circumferentially and parallel to the longitudinal axis 5. According to the embodiment shown in
The fork 10 and 20 and the notched ring 300 comprise means for securing the notched ring to the fork. The interior of the ring 300 is not shown in the figures and comprises an annular groove formed at the edge of the cylindrical inner face of the ring on the side of its smooth portion. The inner diameter of the notched ring is equal to or slightly larger than the outer diameter of the cylindrical part 101 of the fork on which it is positioned. The notched ring is fitted onto the fork by its second end located on the opposite side of its free end as far as the flange 102 so that its inner face rests on the outer face of the cylindrical part 101 of the fork. The complementary shape of the flange 102 and the annular groove of the ring allows the notched ring to slide over the flange with sufficient force to fit into the groove, the groove of the notched ring and the flange 102 thus cooperating together. The flat, perpendicular face of the flange prevents the ring from sliding out of place in the opposite direction. In the case where the bearing element is machined directly with the fork, the toothing 331 is located on the outer face of the cylindrical portion 101.
The notched ring 300 further comprises at least one straight boss formed on its inner side. This straight boss extends from the edge of the ring on the side of the smooth part to its middle part and is parallel to the longitudinal axis 5. The shape of this boss is complementary to the slot 103 of the cylindrical part 101 so that the boss of the notched ring 300 and the slot 103 cooperate with each other when the ring is slipped onto the fork 10 or 20. In another embodiment, the ring comprises a second diametrically opposed boss on its inner surface so that each boss cooperates with each of the two slots in the fork.
The cooperation of the flange 102 with the ring groove as well as the gasket 115 ensure that the ring 300 is held immobile relative to the fork against translational movement in both directions of the longitudinal axis 5. Similarly, the cooperation of the slot 103 with the boss of the ring prevents any rotational movement of the ring around the longitudinal axis 5. Thus, once the notched ring 300 is placed on the fork, it is secured in relation to it.
The connecting rod 1 comprises at least one fastener adapted to connect the two ends 11 of the fork 10 in a direction transverse to the longitudinal axis of the connecting rod. The fastener is a snap-in clip 130 comprising a pin 131 passing through the two openings 13 or the two openings 23 of the ends 11 or the ends 21 of the fork 10 or 20 via two rings 133. The pin 131 is connected to a clip 132 that snaps elastically around the central cylindrical part 101 of the fork, on the smooth part 332 of the notched ring or directly on the fork in the case where the bearing element is machined directly on the fork. Once in place, the snap-in clip 130 allows the connecting rod to be coupled and locked to an external member without preventing its length from being adjusted.
The advantage of this assembly is that it can be made in a few steps and can withstand high traction, compression and temperature gradients and with materials of different expansion coefficients. In fact, the end cap is made of thermoplastic or thermoplastic composite and the tube is made of a thermoplastic or thermosetting composite, e.g., thermosetting carbon. The threaded insert can be made of a polymer such as a thermoplastic, but also of a metal material or a combination of both. The metal material can be aluminum or titanium or an alloy of both. The fork is made of a hollow tubular structure at both ends for weight reasons.
The pressing element of the resisting torque device 30, which is integral with the connecting-rod shank 50, is intended to cooperate with the bearing element of the resisting torque device and thus with the toothing 331. According to a first embodiment of the invention, the pressing element of the resisting torque device 30 comprises at least one ball plunger 530 and the means for securing the pressing element is a receptacle 533 for each ball plunger 530, each receptacle 533 being provided in the wall thickness of the connecting-rod shank and more precisely in the wall thickness of the end cap 53 on the side opposite the tube 55.
When the fork 10 and connecting-rod shank 50 are assembled together, the flush surface of the ball 531 of each ball plunger 530 is in permanent contact with the toothing 331 of the resisting torque device. The ball plungers can no longer be removed from their seats because they are jammed between the end cap 53 and the toothing 331.
The flush surface of each ball cooperates with a recess in the toothing 331. Preferably, the size of the balls is adapted to cooperate with a recess in the toothing 331 and the shape of the recesses in the toothing 331 is complementary to the shape of the balls. The ball plungers are integral with the end cap 53 and thus with the connecting-rod shank. The rotation of the connecting-rod shank drives the ball plungers 530 in rotation. The spring of each ball plunger exerts a force on the ball and thus on the toothing 331 that increases as the ball moves from a gap between two teeth to the adjacent gap. This effort opposes a resistance to the rotational movement of the connecting-rod shank in relation to the fork by friction of the ball against the toothing, which means that the operator must exert a necessary and sufficient torque effort to rotate the connecting-rod shank in relation to the fork. This necessary and sufficient torque must be greater than the resisting torque of each ball 533 on the toothing 331.
Each ball plunger provides an independent and equal point spring effect on the toothing, exerted by the spring pushing on the ball and acting only in the direction of the plunger axis to push the ball into a recess in the toothing. The force exerted by each ball on the toothing 331 is then identical and predictable, which has the advantage of being able to size the desired force by increasing or decreasing the number of ball plungers. The number of plungers can be between 1 and 8.
The length of the connecting rod can be adjusted by screwing or unscrewing the connecting-rod shank in relation to the fork. In the case of a connecting rod with a fork at each end, the connecting-rod shank 50 has two threaded inserts 54 each with a thread 546 and two end caps 53. The threading device of the second fork is oriented in the opposite direction to the threading device of the first fork so that rotation of the connecting-rod shank in one direction causes both forks to extend and rotation of the connecting-rod shank in the opposite direction causes both forks to enter the connecting-rod shank.
According to a second embodiment of the invention illustrated in
The leaf spring 730 is seen in detail in
On the other hand, once the fork is inserted into the connecting-rod shank, the leaf spring cannot be removed from its location because it is wedged between the end cap 53 and the toothing 331 of the resisting torque device. The blade 730 is clamped but not completely immobilized so that there is a gap between the end cap 53 and the toothing 331 for the leaf spring to exert its resilience. The blade 730 has at least one tooth 731 shaped to cooperate with a recess in the toothing 331. When the fork is assembled on the connecting-rod shank 50, the tooth 731 is in permanent contact with the toothing 331 of the resisting torque device.
Preferably, the device according to the invention comprises more than one leaf spring, each leaf spring has a single tooth 731 and all leaf springs are identical. The leaf springs are then positioned side-by-side in the end cap so that the teeth 731 are uniformly angularly distributed. This has the advantage of centering the fork in the connecting-rod shank. Each blade has at least one end inserted into a notch 733 provided in the wall of the end cap 53. Each leaf spring has an independent and equal point spring effect on the toothing exerted by the blade pushing the tooth 731 into a recess in the toothing 331.
The force exerted by each tooth 731 on the notched ring 300 and therefore on the toothing 331 is then identical and predictable, which has the advantage of being able to size the desired force by increasing or decreasing the number of blades as for ball plungers.
In the case of two leaf springs with a single tooth for each leaf, the leaves are positioned so that they are symmetrical with respect to a plane passing through the longitudinal axis 5 of the connecting rod. The two teeth are therefore diametrically opposed and if only one end of each blade is inserted into a receptacle of the end cap, it is either the two ends located closest to the teeth or the two ends furthest from the teeth. This embodiment ensures, like the first embodiment, that the resisting torque does not depend on the direction of rotation of the connecting-rod shank relative to the fork.
According to an alternative embodiment of the second embodiment, the leaf spring has two teeth 731, and these are diametrically opposed as can be seen in
Compared to a single leaf spring with two teeth, the effect of two ball plungers can be predicted and dimensioned more accurately because they exert forces independent of each other. Similarly, a leaf spring with multiple teeth will not have an equivalent reaction to an equivalent number of single-toothed leaf springs, each of which exerts an independent force, such as a ball plunger. Solutions with several ball plungers or several single-tooth leaf springs are therefore preferred to one multi-tooth leaf spring. In all embodiments of the invention, when there are several pressing elements, i.e., a plurality of ball plungers or leaf springs, they are independent of each other and are distributed around the circumference of the connecting-rod shank 50, and thus of the end cap 53, in an angularly uniform manner.
The rotation of the connecting-rod shank and therefore of the end cap 53 causes the leaf spring 730 to rotate. The spring effect of each blade exerts a force on tooth 731 and thus on the toothing 331 that increases as tooth 731 passes from a recess between two teeth of toothing 331 to the adjacent recess. This effort opposes a resistance to the rotational movement of the connecting-rod shank in relation to the fork by friction of the tooth 731 against the toothing, which means that the operator must exert a necessary and sufficient torque effort to rotate the connecting-rod shank in relation to the fork. This necessary and sufficient torque must be greater than the resisting torque of each tooth 731 on the toothing 331.
Regardless of the embodiment of the invention, when no rotational torque is exerted on the connecting rod, the pressing elements exert a radial force on the bearing element perpendicular to the longitudinal axis 5 of the connecting rod. When a rotating torque is exerted on the connecting rod, the pressing element exerts a radial force and a tangential force on the bearing element, both forces being located in a transverse plane and perpendicular to the longitudinal axis 5 of the connecting rod.
The resultant of these two forces contributes to the resisting torque exerted on the connecting rod. As the angle between two teeth of toothing 331 decreases, the resisting torque increases. The angle between two teeth of the toothing 331 is between 60 and 120 degrees. The connecting rod according to the invention provides a resisting torque with preferably a defined value between 0.5 Nm and 10 Nm and preferably between 1 Nm and 3 Nm.
The resisting torque device guarantees the set length of the connecting rod by maintaining a minimum torque resistant to misalignment once the connecting rod has been installed and adjusted in length, even when installed on structures subject to vibration.
Since the load-bearing capacity of the connecting rod according to the invention can be increased by increasing the number of ball plungers or leaf springs, the connecting rod according to the invention can be adapted to more demanding structures without requiring many changes in its manufacturing method. In fact, a plurality of seats for ball plungers or leaf springs can be provided at the time of manufacturing of the end cap and be provided with the required number of plungers or blades to obtain a connecting rod with the desired torque resistance.
The torque exerted to set the connecting-rod shank in rotational motion is applied in the same transverse plane as the resisting torque exerted by the resisting torque device of the connecting rod according to the invention. This is achieved because the pressing element means for securing and the pressing element have a common plane of symmetry perpendicular to the longitudinal axis 5 of the connecting rod. This means that the receptacle 533 and 733 of each pressing element and the pressing element have a common plane of symmetry perpendicular to the longitudinal axis 5 of the connecting rod. The force exerted by the pressing element is also contained in this plane. In other words, the means for securing the pressing element to the end cap is not offset along the longitudinal axis with respect to the axis of the force it exerts.
On the other hand, in all positions of the fork in the connecting-rod shank, the surface in contact with the teeth of the toothing 331 is the same. The advantage of these features is that the torque required to vary the length of the connecting rod is constant regardless of the position of the fork in relation to the connecting-rod shank.
The preferred method of making and assembling a connecting rod according to the invention adapted for use on an aircraft comprises the following steps:
a) the connecting-rod shank 50 consisting of the end cap 53, the threaded insert 54 and the tube 55 is manufactured and assembled in a single injection-molding step,
b) the connecting element 10, 20 is machined in one piece, preferably from a metal material, with a first free end and a second end having a locking device 107, 108,
c) the notched ring 300 comprising the toothing 331 is integrally mounted on the connecting element,
d) the gasket 115 is placed in a groove 105 provided on the connecting element at the end of the notched ring,
e) at least one ball plunger 530 or leaf spring 730 is placed in the receptacle provided for this purpose in the wall thickness of the end cap,
f) the connecting element is inserted and screwed into the connecting-rod shank by cooperation of the threads and until the two blades 107 at the opposite end of the free end of the connecting element come to rest with their locking element in the form of a radially outwardly projecting bead 108 against the end of the threaded insert, the locking device thereby being automatically inserted.
According to a method of manufacturing and assembling the connecting rod according to the invention adapted for use on any type of structure, the toothing 331 is directly machined on the connecting element. The method comprises the following steps:
a) the connecting-rod shank 50 consisting of the end cap 53, the threaded insert 54 and the tube 55 is manufactured and assembled in a single injection-molding step,
b) the connecting element 10, 20 is machined in one piece, preferably from a metal material, with a first free end and a second end having a locking device 107, 108, and a central portion comprising the toothing 331,
c) the gasket 115 is placed in the groove 105 provided on the connecting element,
d) at least one ball plunger 530 or leaf spring 730 is placed in the receptacle provided for this purpose in the wall thickness of the end cap,
e) the connecting element is inserted and screwed into the connecting-rod shank by cooperation of the threads and until the two blades 107 at the opposite end of the free end of the connecting element come to rest with their locking element in the form of a radially outwardly projecting bead 108 against the end of the threaded insert, the locking device thereby being automatically inserted.
The manufacturing method of the connecting rod is such that once the connecting rod is assembled it is no longer possible to separate the fork from the connecting-rod shank, as the means of locking the fork in the connecting-rod shank are automatically put in place. The assembled connecting rod is a one-piece device. As a result, the two elements of the resistant torque device (including the bearing element attached to the fork and the pressing element attached to the connecting-rod shank) can no longer be disengaged from each other. The connecting rod cannot change length without the resisting torque device being activated.
The connecting rod according to the invention has the advantage of having a strong torque device that is active at all times and cannot be dismantled. Even in the event of incorrect assembly of the snap-in clip by the operator, the resistant torque is guaranteed by the connecting rod according to the invention, which is essential for use on aircraft. Since the snap-in clip has the sole function of connecting the connecting rod to its intended installation location, it does not apply any additional force to the rotational movement of the connecting-rod shank relative to the fork.
On the other hand, since the notch is not placed on the part of the connecting rod with the largest diameter, the connecting rod according to the invention reduces the risk of injury to the operator who handles and places the connecting rod.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2020/000032 | 2/14/2020 | WO |
