WO2018055289A1

WO2018055289A1 - Movable vehicle body element with shape memory alloy

Info

Publication number: WO2018055289A1
Application number: PCT/FR2017/052522
Authority: WO
Inventors: Jérôme Grando; Frédéric STABLO
Original assignee: Compagnie Plastic Omnium
Priority date: 2016-09-22
Filing date: 2017-09-20
Publication date: 2018-03-29
Also published as: FR3056272A1; FR3056175B1; FR3056175A1

Abstract

- The invention relates to a motor vehicle body element (10) comprising at least one movable wall (20) made of a plastic material, characterised in that it comprises a device (30) for deforming the wall (20), said device (30) comprising at least one wire (40) made of shape memory alloy connecting at least a first zone (50) and a second zone (60) of said wall (20), said wire (40) being fastened to the first zone (50) by means of at least one mechanical anchor point (82), the wire (40) being kept at a non-zero distance from said wall (20), and said wire (40) being capable of changing length.

Description

The invention relates to the field of the automotive industry, and in particular the mechanisms for actuating the movement, relative to the rest of the vehicle, of vehicle body elements.

Various parts of bodies that can be moved by displacement relative to the rest of the vehicle are known. These parts will be noted in the rest of the description: "moving parts". For example, the following moving parts can be cited without limitation:

spoilers (or "spoilers" or baffles) at the rear of a vehicle; a spoiler is a bodywork part forming an extension of the roof positioned on the rear of a vehicle, and intended to improve the aerodynamics of the vehicle on which this part is placed. The spoilers are also used for aesthetic aspects (style) of the vehicle. They are located and fixed at the top and rear of the vehicle between the roof and the top edge of the telescope, on the roof or on the tailgate. Some spoilers are also devices for cleaning the rear window, redirecting the air passing over the vehicle to the rear window, so as to drive rainwater.

movable panels mounted on these spoilers for aerodynamic reasons or for cleaning the rear window;

aerodynamic flaps mounted at the front of the vehicle, to improve the aerodynamics of the vehicle;

the sets of blades, called "aeroshutter" in English, at the level of the front air intake grille of the vehicle, and for example to modify the conditions of entry of air into an engine compartment and promote heat exchange , or obscure or discover technical equipment for driving assistance such as a laser. These multiple features may be required simultaneously or independently of each other;

plastic body panels to optimize the aerodynamics of a motor vehicle.

To move such movable body parts, it is known to use motor means with members such as cylinders, worms ....

However, such solutions lead to an increase in the mass of the vehicle, a power consumption for the operation of the engine, and a large footprint in generally very small spaces. Such solutions also pose problems of compatibility with other characteristics of the body panels such as: the management of small shocks (the elements useful for the displacement are rigid and thus cause damage to the vehicle in case of shock, or even damage to a pedestrian) ; system compatibility electronic; energy consumption ; robustness ; difficulty of assembly and adjustment.

Finally, such solutions are based on a design of a moving part by displacement, then an assembly of this part on the vehicle, the realization of a connection with a motor means and with other interface members. ..

To overcome the solutions based on motor means for moving an element, solutions based on materials made of shape memory alloy (AMF) are known. Indeed, the ease of use and the mechanical performance of these materials can reproduce the behavior of engines with a much smaller footprint and mass.

Document US11116433 is known, for example, a solution using a shape memory alloy wire encapsulated in the part to be moved. However, this solution is very difficult to set up for plastic parts. Indeed, during the manufacture of the bodywork element, it is necessary to provide a step of inserting the wire during molding of this element. However, it is very difficult to keep a wire in place in a molding impression. However, the position of the wire must be very precise, so that the movable wall deforms correctly with respect to its function. In addition, the presence of a heat-generating wire in the middle of the plastic material is undesirable. Indeed, a heating of the plastic material could: alter the aesthetic appearance and the mechanical properties of this element; lead to a separation of the wire and the wall after multiple actuations; causes problems of cooling the wire so that it quickly returns to its original shape. The latter may be crucial for some applications, for which mobility in one direction and the other must be rapid. This can be the case for aerodynamic blades mounted on the front of the vehicle.

Document FR1553448 is also known, a solution in which shape memory alloy (AMF) materials are used to actuate a pusher for moving a moving part. However, such a solution still requires mechanical means (pusher) rigid, heavy and requiring several assembly operations.

The object of the invention is to overcome these drawbacks by providing a bodywork element comprising a plastic wall capable of being mobile, not by displacement, but by deformation (by bending for example), simple to manufacture, and preserving the integrity of the body. body element during its manufacture and during deformation of the wall, and limiting the impact on the free volume behind the bodywork element. The invention achieves this by providing the body member with a wall deformation device incorporating a shape memory alloy wire. Thus the object of the invention relates to a bodywork element of a motor vehicle, comprising at least one movable wall made of plastic material, and a device for deformation of the wall. This device comprises at least one shape memory alloy wire connecting at least a first zone and a second zone of the wall, the wire being fixed to the first zone by at least one mechanical anchor point which can also form an electrical connector. the wire being held at a non-zero (but not necessarily constant) distance from the wall. This wire is able to change its length when it is traversed by a current, this change causing a deformation of the wall.

Such a bodywork element has at least the following advantages:

- a saving in weight compared to traditional systems with motors and cylinders;

a small footprint.

- reduced energy consumption compared to traditional systems with motors and cylinders.

a better compatibility of the system with respect to the conventional points of the specifications of bodywork parts (in particular the impact behavior, because the wire is a flexible element).

The system may further include one or more of the following features, taken alone or in combination:

- The wire is able to shorten when it is traversed by a current, this shortening causing a deformation of the wall;

- The wire is fixed to the mechanical anchoring point forming a first pad in a first zone, and a second pad in a second zone, said pads being configured to maintain the non-zero distance above said wall; the studs are fixed on a surface of the wall that is not visible from the outside of the vehicle by gluing, screwing, welding, riveting, or by means of material;

the wire forms a loop between said first and second pads;

the studs are fixed on the wall along an edge of the wall;

- The body member comprises at least one intermediate pad, between the first and the second pad, wherein the wire is guided and held at the non-zero distance above said wall;

- The bodywork element comprises several, preferably 2, sets formed by a first pad, a second pad, and a wire, each set being positioned on an edge of the wall, preferably on two substantially parallel edges;

at least one assembly comprises at least one intermediate pad, between the first and the second pad, and wherein the wire is guided and maintained at the non-zero distance above said wall;

the wall has a curve;

- The body element comprises a locking system of the wall in the deformed position, for releasing the current in the wire;

- The body element comprises a thermal protection system of the environment of the wire;

the body member has a wire cooling system;

the bodywork element forms a bumper skin, in which the wall is an air intake blade;

a first zone is located towards the center of the bumper skin once mounted on a vehicle, and a second zone is located towards a lateral edge of the bumper skin once mounted on a vehicle;

- The bodywork element comprises a current generating device connected to an electrical connector.

The invention also relates to a motor vehicle comprising a bodywork element according to the invention.

The invention will be better understood on reading the appended figures, which are provided by way of examples and are in no way limiting, in which:

FIG. 1 illustrates an exemplary embodiment of a bodywork element 10.

- Figure 2 illustrates an embodiment of a body member 10 and its deformation device.

FIGS. 3A to 3D illustrate various embodiments of pads that can be used to anchor, guide and / or keep the wire away from the wall and / or electrically power it.

- Figure 4 illustrates the principle of deformation of a wall by means of the deformation device.

- Figure 5 illustrates a bumper skin provided with movable walls activated by the deformation device.

FIGS. 6, 7 and 8 illustrate two embodiments of the deformation device that can be used for the bumper skin of FIG. 5.

Referring now to Figures 1 and 2 which illustrate an embodiment of a body member 10. This comprises at least one movable wall 20 made of plastic material and a deformation device 30 of the wall 20.

Figure 1 illustrates the movable wall 20 between a first position (in gray and solid line) and a second position (dotted line) in which the wall is deformed. The passage from one position to another, is by deformation of the wall 20, and not by displacement of this wall 20. Thus, it is not a matter of applying a rotation around a reference zone (forming an axis A in Figure 1), but to deform, twist, the wall 20 from the zone A.

It is said that there is solid displacement of an organ, unlike a deformation, when the member is movable without deformation, that is to say that the body due to its rigidity has a negligible deformation or imperceptible in relation to its displacement.

Deformation is characterized with respect to a reference point. Thus the zone A constitutes a point of reference in FIGS. 1 and 2. A reference point is a zone of the wall which remains fixed with respect to the bodywork element 10. As a result, the reference point can also be a area of the bodywork element 10.

Zone A may correspond to the junction between the wall 20 and the rest of the bodywork element 10. The wall 20 and the bodywork element may be a single piece. Mobility is then made possible by performing separations (laser cutting for example) in the bodywork element 10 along the periphery of the wall 20, with the exception of at least one zone, called the junction zone 22. .

The deformation device 30 comprises at least one shape memory alloy wire 40 connecting at least a first zone 50 and a second zone 60 of the wall 20. The wire 40 is fixed to the first zone 50 by at least one point d mechanical anchoring 82 can also form an electrical connector. The zone 50 constitutes a point of reference of the deformation. The wire 40 is held at a non-zero distance L (which can be variable) above the wall 20, and is connected to a current generating device 70 via an electrical connector 83 (which may be coincident with the point d mechanical anchoring 82). The wire 40 is able to change its length when it is traversed by the current of the device 70. This change causes a deformation of the movable wall 20.

The shape memory alloy wire 40 may be configured to shorten when a current flows through it, this shortening causing deformation of the wall 20, or on the contrary, to lengthen. The choice is made according to the desired deformation.

Keeping the wire 40 at a non-zero distance above the wall 20 has several effects:

- Facilitates the deformation of the wall 20, improving the traction effect on the movable wall. Preferably the wall 20 of the bodywork element 10 is not flat but has a curve. Such a configuration facilitates the drawing of the wall including the right zone 60; - Limit or even prevents heating of the plastic body member 10, and thus preserves the aesthetic appearance and mechanical properties of this element;

- preserves the mechanical and aesthetic properties of the bodywork element 10 by avoiding inserting the wire more or less deeply in its thickness;

facilitates the manufacture of the bodywork element by avoiding a step of insertion of a wire during the molding of this element. Indeed, it is very difficult to keep in place a wire in a molding chamber. However, the position of the wire must be very precise, so that the movable wall deforms correctly with respect to its function; and

- facilitates the cooling of the wire, so that it returns to its original shape, and therefore that the wall 20 also returns to its original shape.

According to one embodiment, the wire 40 connects the two zones 50 and 60, and is maintained at a non-zero distance above the wall 20, by means of a network of pads 80. These pads 80 constitute interfaces between the wire 40 and the wall 20. The studs can have several functions:

a stud constitutes the mechanical anchoring point 82;

a stud 84 constitutes a connection with the zone 60;

- One or more intermediate pads 88, positioned between the pads 82 and 84, constitute guide elements of the wire 40.

Each stud makes it possible to keep the wire 40 at a distance from the wall 20. Each stud contributes to pulling the wall 20 when the wire 40 shortens under the effect of the electric current. The wire may be anchored to these pads 80, or simply brought into contact to slide under the effect of its retraction.

At least, an intermediate stud 88 guides the wire along the direction to be deformed of the wall, to facilitate and locally adjust the forces and deformations to be applied punctually. It also keeps the distance to the wall, especially when the pads 82 and 84 are remote. Thus, and preferably, the pads 82, 84, 88 are fixed on the wall 20. They are distributed on the surface to better distribute the forces. Indeed, the studs work in tension. Thus, when the wire 40 undergoes a shortening, the wall 20 is deformed by pulling the wire 40 on the wall 20 at each stud.

Thus, according to an exemplary embodiment, the wire 40 is fixed to the first stud 82 connected to the current generator device 70 in the first zone 50, and to the second stud 84 in the second zone 60. These studs 82 and 84 are configured to maintain the non-zero distance above said wall. They thus have a point of attachment (plot 82), or simply contact (pad 84), with the wire 40, positioned at a given height of the wall 20.

The pads 80 (82, 84, 88) can be made of any material. Preferably, a material is selected, at least for the part in contact with the wire 40, resistant to the temperatures reached by the wire 40 when a current flows through it. These temperatures can reach Ι δΟ 'Ό. For example, a metal may be used.

Preferably, the pads 80 are made at least partially in a plastic material, and they comprise at least one zone 86, able to be in contact with the wire 40, made of a material resistant to the temperatures reached by the wire 40 when is traversed by a current.

FIGS. 3A to 3D illustrate examples of embodiments of pads 80. FIG. 3A illustrates an anchor-type pad 80 and electrical connector 83. FIG. 3B illustrates an example of an intermediate pad 88 and pad 84 when the thread has to loop. Element 86 is a metal bar for example. FIG. 3C illustrates an intermediate stud type pad 88. The element 86 is a metal ring for example. Figure 3D illustrates an intermediate stud type pad 88 or a stud 84 when the wire must loop. Element 86 is a metal bar for example. The cup on the top of this bar prevents the wire 40 from disengaging the stud.

Preferably, the pads 80 are fixed on a surface of the non-visible wall of the outside of the vehicle.

To do this, the pads 80 can be reported by clipping, gluing, gluing, screwing, welding, riveting, molding (molded inserts), or material (plastic elements molded with the wall 20), or by 3D printing on the wall 20. FIG. 4 illustrates the operating principle of the deformation device 30:

the arrows F1 (solid line) indicate the continuous shortening of the length of the wire 40 when it is traversed by a current;

the arrows F2 (dotted line) indicate the point deformation of the wall 20 at the level of each block;

the arrow F3 (vertical) indicates the total deflection induced on the wall 20.

By activating the wire 40 by Joule effect heating (by means of the current generator 70), a contraction of the wire 40 occurs in its length (arrows F1). The wire 40 being secured (even by sliding connection) to the pads 80, a force (arrows F2) is exerted on each pad which transmits it punctually to the wall 20 to which they are secured.

According to a preferred embodiment, the wire 40 forms a loop between the pads 82 and 84. The wire 40 is thus fixed by one of its ends to the pad 82, by which it can be supplied with current. Then the wire 40 passes at the stud 84, then returns to the pad 82, where it is fixed by its other end. The wire 40 can pass through different pins 88 to back of the loop as shown in Figure 6.

This configuration makes it possible to use the wire 40 as the conducting wire of the current, and thus avoids the introduction of another electric wire. In addition, the loop doubles the useful length to the deformation of the wall. Thus the pulling force exerted on each pad 80 (82, 84 and possibly 88) is double. The presence of a loop of the wire 40 may alternatively make it possible to reduce the diameter of the wire for the same pulling force. Thus, the energy required to heat the wire so that it changes length is less.

According to an exemplary embodiment, the wall 20 comprises several, preferably 2, sets formed by a first pad 82, a second pad 84, optionally one or more intermediate pads 88, and a wire 40.

According to one embodiment, the body member 10 comprises a locking system (not shown) of the wall 20 in the deformed position, for cutting the current in the wire 40, while maintaining the wall 20 in the deformed position.

According to one embodiment, the body element 10 comprises a thermal protection system 100, to protect the environment of the wire 40. Indeed, it is possible that the activation of the wire 40, causes an increase in temperature incompatible with the stability of the elements of its neighborhood. For example, for a plastic part, it must not melt under the effect of the heat released by the wire 40.

Thus, according to one embodiment, the wall 20 comprises a thermal protective film, on its surface comprising the deformation device 30, at the passage of the film. This film can be for example overmolded.

In another example, the wall 20 has insulating interfaces reported around the wire or between the wire 40 and the neighborhood element to be protected.

According to one embodiment, the bodywork element 10 comprises a cooling system (not shown), for cooling the wire 40, so that it quickly resumes its initial position.

According to an exemplary embodiment, the cooling system comprises Peltier-effect components, in the form of small plates that are glued, adhesively bonded or overmolded.

The cooling system can also be activated in case of overheating of the environment of the wire 40.

Reference is now made to FIG. 5 to illustrate an exemplary embodiment of a bodywork element 10.

According to this example, the body member 10 is a front bumper skin of a motor vehicle. This bumper skin 10 comprises a set of movable walls 20 forming front air inlet blades of the vehicle. These blades extend, once the bumper skin 10 mounted on the vehicle to the side of the vehicle, as shown in Figure 5. They thus form wings connected to the center. Each blade corresponds to a cut of the bumper skin 10. Thus, these cutouts schematically comprise:

- two separations (cutouts) 24 and 26 substantially parallel and horizontal relative to the ground once the element 10 mounted on the vehicle;

- A substantially vertical separation (cut) 28 and making the connection with the other two cutouts, this vertical cutout being positioned on one side of the bumper skin.

According to this embodiment, the blades and the deformation device 30 are arranged so that the blades open towards the inside of the vehicle. Depending on the location of the reference point, the air is thus directed to the wheels or to the center (Y0) of the vehicle where the radiator is often located.

As illustrated in Figure 5, the blades 20 are nested within each other.

These blades are equipped on their non-visible face, therefore preferably on the concave face if the wall 20 is curved, from the outside of the vehicle, with a deformation device 30.

As illustrated in FIGS. 6 and 7, for each blade 20, the deformation device 30 comprises on each of the two substantially parallel and horizontal cutouts a set of intermediate pads 88, between the first 82 and the second stud 84.

The wire 40 is guided and maintained at the non-zero distance above the wall 20 by means of these pads.

In the example of Figure 6, the wire 40 forms a loop, the wire 40 passing successively into the pad 82, a first set of intermediate pads 88a, the pad 84, and a second set of intermediate pads 88b.

In the example of Figure 7, the wall 20 is equipped with two deformation devices 30a and 30b. These devices are installed along the two cutouts 24 and 26.

In the example of Figure 8, the wall 20 is equipped with two deformation devices 30a and 30b. These devices are installed along the two cutouts 24 and 26. For each of them the thread makes a loop.

According to these examples, the second zone 60 is located towards a distal edge of the bumper skin once mounted on a vehicle.

According to an exemplary embodiment:

- The bumper skin is made of plastic selected from the following materials: thermoplastic (polypropylene, polyamide), thermosetting (epoxy, vinylester), optionally loaded reinforcing fibers such as fiberglass, carbon, aramid, ...

the skin has a thickness of between 1 and 5 cm, preferably between 2 and 3 cm;

the length of a blade (movable wall 20) is between 10 and 100 cm, and its height is from 1 to 50 cm;

the wire has a diameter of between 0.05 and 2 mm;

the wire is made of a shape memory alloy such as: Titanium-Nickel alloys, Copper-Zinc-Aluminum alloys, Copper-Aluminum-Nickel alloys and shape-memory polymers.

- The blade opens from 1 to 150mm at its end farthest from the reference point, towards the inside of the vehicle.

The invention also relates to a motor vehicle comprising a bodywork element 10 according to the invention.

Claims

1. Body element (10) of a motor vehicle comprising at least one movable wall (20) made of plastic, characterized in that it comprises a device for deformation (30) of the wall (20), said device (30) ) comprising at least one shape memory alloy wire (40) connecting at least a first zone (50) and a second zone (60) of said wall (20), said wire (40) being fixed to the first zone (50) by at least one mechanical anchoring point (82), the wire (40) being held at a non-zero distance from said wall (20), and said wire (40) being able to change length when is traversed by a current, this change causing a deformation of the wall (20).

2. Body element (10) according to claim 1, wherein the wire (40) is adapted to shorten when it is traversed by a current, the shortening causing a deformation of the wall (20).

Bodywork element (10) according to one of the preceding claims, wherein the wire (40) is fixed to the mechanical anchoring point forming a first stud (82) in a first zone, and a second stud in a first zone. second zone, said pads being configured to maintain the non-zero distance above said wall.

4. Body element (10) according to the preceding claim, wherein the studs are fixed on a surface of the non-visible wall of the outside of the vehicle by gluing, screwing, welding, riveting, or by material.

5. Body element (10) according to one of claims 3 and 4, wherein the wire forms a loop between said first and second pads.

6. Body element (10) according to one of claims 3 to 5, wherein the studs are fixed on the wall along an edge of the wall (20).

7. body element (10) according to one of claims 3 to 6, comprises at least one intermediate pad, between the first and the second pad, wherein the wire is guided and maintained at the non-zero distance above said wall.

8. body element (10) according to one of claims 3 to 7, comprising several, preferably 2, sets formed by a first pad, a second pad, and a wire, each set being positioned on an edge of the wall (20), preferably on two substantially parallel edges.

9. body element (10) according to the preceding claim, wherein at least one assembly comprises at least one intermediate pad, between the first and the second pad, and wherein the wire is guided and maintained at the non-zero distance to- above said wall.

10. Body element (10) according to the preceding claim, wherein the wall presents a curve.

11. Body element (10) according to one of the preceding claims, comprising a locking system of the wall (20) in deformed position, for releasing the current in the wire 40.

12. Body element (10) according to one of the preceding claims, comprising a thermal protection system (100) of the environment of the wire (40).

13. Body element (10) according to one of the preceding claims, comprising a wire cooling system (40).

14. Body element (10) according to one of the preceding claims, forming a bumper skin, wherein the wall (20) is an air inlet blade.

Bodywork element (10) according to the preceding claim, wherein a first zone (50) is located towards the center of the bumper skin when mounted on a vehicle, and a second zone is located towards a lateral edge of the bumper skin. bumper skin once mounted on a vehicle.

16. Body element (10) according to one of the preceding claims, comprising a current generating device (70) connected to an electrical connector (83).

17. Motor vehicle comprising a bodywork element (10) according to one of the preceding claims.