FR3069226A1 - REAR DIFFUSER WITH SLIDING LINKS - Google Patents

Abstract

The invention relates to a rear diffuser (2) of a motor vehicle comprising at least one movable panel (6) between an extended position and a retracted position when the rear diffuser (2) is attached to a body part (4) of a motor vehicle , the rear diffuser (2) comprising a motorized mechanism adapted to allow a portion of the movable panel (6) in the deployed position to be pressed against the bodywork part (4) when the rear diffuser (2) is fixed on the piece of bodywork (4) of a motor vehicle.

Description

The invention relates to rear diffusers of a motor vehicle and more particularly to mobile rear diffusers.

The rear diffuser is a part which can be present at the rear of a motor vehicle, more precisely under the chassis or else in the lower part of the bumper, and having the aim of improving the aerodynamic performance of the vehicle. It can for example be to improve the vehicle's ground support.

Some diffusers improve the aerodynamic performance of the vehicle by reducing the drag of the vehicle, that is to say the force opposing the movement of the vehicle in the air. It is a question of shifting backward the detachment points of the air relative to the vehicle, that is to say the points at which the air no longer follows the bodywork. This makes it possible to push back the depression created at the rear of the vehicle and thus limit the retaining effect (called "suction effect") of this depression on the motor vehicle.

Current solutions, such as that described in document US 2017/113741, consist of a rear diffuser comprising a panel movable in rotation between a retracted position and a deployed position when the vehicle is in motion. The rotation from the deployed position to the retracted position makes it possible to push back the detachment points of the air and thus reduce the drag of the motor vehicle as explained previously. The movable panel is deployed from a certain speed to reduce the drag of the vehicle and is folded up at high speed.

However, and in order to optimally reduce the drag of the vehicle, it may be necessary to make a significant rotational movement in order to offset the depression created at the rear of the vehicle sufficiently backwards. This significant rotational movement has the consequence of greatly moving the movable panel away from the rest of the motor vehicle because the movable panel is curved. Therefore, the distance between the center of the movable panel and the vehicle is important. In addition, a rotation through a large angle (but necessary to obtain the expected effect) can cause the movable panel to pass under the minimum ground clearance of the vehicle, that is to say the distance between the ground and the lowest point of the chassis which must not come into contact with the ground. This passage under ground clearance leads to a passage of the air flow above the movable panel. This passage of the air flow over the movable panel, between the movable panel and the bodywork, leads to increasing the ground support of the vehicle. However, this increase in ground support is not a characteristic sought in this scenario. Worse, the support on the ground being characterized by the exertion of a force from the top to the bottom on the mobile panel, it is then difficult to retract the mobile panel or even to maintain it in position in a stable manner. It is therefore necessary to provide a significant dimensioning of the actuator output torque allowing the movements of the movable panel.

The force mentioned above also generates turbulence at the movable panel when it is deployed, which causes difficulties in holding it in position. As this turbulence intensifies at high speed, it then becomes essential to retract the movable panel at high speed using an actuator having a high output torque.

A simple rotational movement of the movable panel can also lead to damage to the movable panel, for example the appearance of scratches due to the curve of the movable panel. In other words, if the movable panel is kept too close to the vehicle, friction can occur and damage the movable panel due to its curve.

The object of the invention is to provide a rear diffuser for a motor vehicle making it possible to effectively reduce the aerodynamic drag of the motor vehicle while guaranteeing on the one hand easy deployment and maintenance in position of the movable panel and on the other hand the preservation of the aesthetic aspect of the diffuser.

The subject of the invention is a rear diffuser for a motor vehicle comprising at least one panel movable between a deployed position and a retracted position when the rear diffuser is fixed to a bodywork part of a motor vehicle, the rear diffuser comprising a motorized mechanism capable of allowing a part of the movable panel in the deployed position to press against the bodywork part when the rear diffuser is fixed to a bodywork part of a motor vehicle.

Thus, the movable panel in the deployed position does not allow air to pass over it. This positioning directs air from the base of the vehicle to the bottom of the diffuser. The absence of air passage on the upper part of the diffuser makes it possible to avoid the exercise of a vertical force (from top to bottom) on the deployed mobile panel, which makes it easier to retract or keep the movable panel in position.

This orientation of the air from the base of the vehicle to the lower part of the diffuser also limits the turbulence due to possible play ("aerodynamic walking"), or during transitions of the position of the diffuser (continuity of surfaces at the aerodynamic scale).

The rear diffuser may also include one or more of the following characteristics, taken alone or in combination:

- The movable panel is able to deploy and retract along a path following a combined movement of translation and rotation;

- the motorized mechanism includes two deployment rods;

- the two deployment links are linked to each other;

- The first deployment link is able to set in motion the second deployment link;

the setting in motion of the second deployment rod by the first deployment rod is capable of being carried out by means of a connecting member comprising a pin connected to the first deployment rod and a cylinder linked to the second rod deployment;

- the pin and the cylinder are pivotally mounted relative to each other;

- The cylinder is slidably mounted along the second deployment rod, preferably by means of a sliding pivot type connection;

- the two deployment connecting rods are capable of being set in motion by an actuator capable of allowing rectilinear actuating movement;

- The actuator is able to set in motion the first deployment rod; and

- the actuator is chosen from a cylinder, a shape memory alloy actuator or a slide.

The invention also relates to a motor vehicle body part comprising a rear diffuser according to the invention.

Advantageously, the bodywork part is a rear bumper of a motor vehicle.

We will now present an embodiment of the invention given by way of nonlimiting example and with the support of the appended figures in which:

- Figure 1 shows a vehicle whose rear bumper comprises a rear diffuser according to the invention, the rear diffuser being in the retracted position;

- Figure 2 shows a vehicle whose rear bumper comprises a rear diffuser according to the invention, the rear diffuser being in the deployed position;

- Figure 3 is an enlargement of a motorized mechanism for deploying and retracting the movable panel of the rear diffuser according to the invention, the motorized mechanism being in a configuration corresponding to the movable panel in the retracted position;

- Figure 4 is an enlargement of a motorized mechanism for deploying and retracting the movable panel of the rear diffuser according to the invention, the motorized mechanism being in a configuration corresponding to the movable panel during deployment or retraction; and

- Figure 5 is an enlargement of a motorized mechanism for deploying and retracting the movable panel of the rear diffuser according to the invention, the motorized mechanism being in a configuration corresponding to the movable panel in the deployed position.

The figures show a rear diffuser in its configuration mounted on a motor vehicle body part, more specifically a rear bumper of a motor vehicle.

Thereafter, terms such as "longitudinal axis X", "transverse axis Y", "vertical axis Z", "front", "rear", "above", "upper", "below", "Lower", etc. means with reference to the usual orientation of motor vehicles according to the reference shown in Figure 1 for example.

The figures illustrate a rear diffuser 2 of a motor vehicle, for example made of plastic, mounted on a rear bumper 4, for example also made of plastic, and comprising at least one movable panel 6 between a deployed position and a retracted position when the rear diffuser 2 is fixed to a rear bumper 4 of a motor vehicle, the rear diffuser 2 comprising a motorized mechanism capable of allowing a part of the movable panel 6 in the deployed position to be pressed against the bodywork part 4 , here the rear bumper, when the rear diffuser 2 is fixed to the rear bumper 4. The rear diffuser 2 can also include a fixed part, for example a frame fixed to the rear bumper 4, not shown in the FIGS.

The rear diffuser 2 is therefore able to pass from a retracted position shown in FIG. 1, in which the movable panel 6 can be pressed against the rear bumper 4, in a deployed position, in which a lower end 8 of the movable panel 6 is pressed under the rear bumper 4, more precisely under the bottom line of the vehicle corresponding to the line of separation of the air flow from the rear bumper 4. This configuration in the deployed position makes it possible to prevent the air from pass over the movable panel which avoids the formation of support in a direction parallel to a vertical axis Z while making it possible to reduce the aerodynamic drag by pushing back the detachment points of the air flow .

It is possible to maintain a distance of the order of 1 to 2 centimeters between the rear bumper 4 and the movable panel 6 in the retracted position in order to provide a space allowing to contain dirt, which could be deposited when the movable panel 6 is in the deployed position, without disturbing the motorized mechanism.

The movable panel 6 is therefore able, thanks to a trajectory following a combined movement of translation and rotation, to move away initially from the rear bumper 4 then to pass under the skirt of the motor vehicle so that the end 8 of the movable panel 6 is pressed under the rear bumper 4. The trajectory of the movable panel 6 allows it to move away from the vehicle before pressing against the latter which avoids damaging the movable panel 6 to cause of possible friction.

The rear diffuser 2 comprises, in the example illustrated in FIGS. 1 and 2, two motorized mechanisms capable of deploying and retracting the movable panel 6. Each motorized mechanism comprises a first deployment rod 10 and a second deployment rod 12.

In the example shown in Figures 3 to 5, the first deployment rod 10 has a first end 13 connected to the movable panel 6 and a second end 14 connected to the actuator 16. It should be noted that the actuator properly speaking is not shown in the figures, the reference 16 designating the location of this actuator. For the sake of readability, we will speak later of "actuator 16". These two ends are pivotally mounted relative to the means to which they are connected. The second deployment rod 12 has a first end 18 connected to the movable panel 6 and a second end 20 connected to the rear bumper 4 (the end 20 can also be connected to any other fixed part of the vehicle, of the chassis, such as the fixed part of the rear diffuser 2). The end 20 is pivotally mounted relative to the rear bumper 4 (or to the fixed part of the rear diffuser 2) and the end 18 is also pivotally mounted relative to the movable panel 6. The two deployment connecting rods 10 and 12 are connected to each other by means of a connecting member 22 composed of a pin 26 fixed on the first deployment link 10 and a cylinder 24 carried by the second deployment link 12. The cylinder 24 is sliding on the second connecting rod 12 and advantageously in a sliding pivot with this second connecting rod 12 to allow it to slide correctly even if there is a slight clearance between the parts. The pin 26 and the cylinder 24 are pivoted relative to one another. This link allows the second deployment link 12 to be set in motion by means of the first deployment link 10 which is itself set in motion by the actuator 16.

We have described an exemplary embodiment in which the ends 13 and 14 are pivotally mounted relative to the means to which they are connected. It would not go beyond the scope of the invention if at least one of the ends 13 and 14 was connected by a ball joint to the means to which they are connected. It is the same for the end 18 which can also be connected by a ball joint to the movable panel 6

The actuator 16 can be chosen from an actuator, an actuator made of a shape memory alloy (that is to say an actuator composed of an alloy having the following properties: the ability to keep a shape in memory initial and to return to it even after a deformation, the possibility of alternating between two previously memorized forms when its temperature varies around a critical temperature, and a superelastic behavior allowing elongations without permanent deformation superior to those of other metals) or another classic slide. In general, this actuator 16 may be able to allow a rectilinear actuation movement. This makes it possible to reduce the bulk, mainly in a direction parallel to a longitudinal axis X of the vehicle, since the deployment and retraction of the movable panel 6 by a combined movement of translation and rotation can be achieved by an actuator such as a cylinder which can be positioned in order to carry out a thrust in a direction perpendicular to the longitudinal axis X and deployment connecting rods 10 and 12 which, when the movable panel is in the retracted position, occupy a small space in a direction parallel to the longitudinal axis X.

In the example in the figures, the actuator 16 (which can for example be a jack) performs movements in a direction parallel to the vertical axis Z of the vehicle, which reduces the bulk in a direction parallel to an axis longitudinal X of the vehicle. It is possible to ensure this reduction in size by using a movable actuator only in translation. This is for example the case of a cylinder.

When the movable panel 6 is deployed, the actuator 16 is activated (the activation mechanism of the actuator 16 is not shown). We will describe an example in which the actuator 16 is a jack. The actuated cylinder will exert a thrust from top to bottom, in the example illustrated in the figures, in a direction parallel to a vertical axis Z of the motor vehicle.

This push has the consequence of lowering the first deployment rod 10 by exerting a force on its end 14. The first deployment rod 10 will then pivot around these ends 14 and 16 which allows an outlet of the movable panel 6 in directions parallel to the longitudinal axis X of the vehicle but also in a direction parallel to the vertical axis Z of the motor vehicle. The different pivotings made by the first deployment link 10 are observed in FIGS. 4 and 5.

During its movement, the first deployment rod 10 drives the second deployment rod 12 thanks to the connecting member 22, as can be seen in FIG. 4. In this case, and due to the change in position of the first connecting rod 10, the pin 26, which is fixed on the first connecting rod 10, also changes position. The cylinder 24 is then driven in turn via the pivot link between it and the pin 26. By changing position, the cylinder 24 drives the second connecting rod 12 and the end 18 then changes position, which therefore requires movement to the movable panel 6. The cylinder 24 is sliding along the second connecting rod and advantageously in a sliding pivot to allow it to slide correctly even if there is a slight clearance between the parts. In other words, the two deployment rods 10 and 12 are capable of sliding relative to one another, the displacement of the second deployment rod 12 also influencing the displacement of the first deployment rod 10. The second deployment link 12 will then pivot around its second end 20 as can be seen in FIGS. 4 and 5 until it is positioned, in the example shown in FIG. 5, in a position parallel to the longitudinal axis X of the vehicle. This movement allows the mobile panel 6 to pivot in addition to the movements described above.

The movements imposed by the two deployment connecting rods 10 and 12 lead to a movement of the movable panel 6 describing a part of an ellipse. This movement allows the movable panel 6 to exit the vehicle profile (staying close to the latter in order to limit the air passing between the vehicle and the movable panel 6) then to press against the bottom line of the latter. The upper end 28 of the movable panel 6 is far away from the vehicle in a direction parallel to the longitudinal axis X while the lower end 8 is pressed under the low line of the vehicle.

When the movable panel 6 is retracted, the jack performs a movement opposite to that carried out during deployment, which causes the first deployment link 10 which will itself drive the second deployment link 12. The two deployment links return at their respective initial positions (visible in FIG. 3), which made it possible to retract the movable panel 6 so that the latter occupies the position illustrated in FIG. 1.

The invention is not limited to the embodiments presented and other embodiments will be apparent to those skilled in the art.

It is in particular possible that the deployment rods have different amplitude strokes so that the deployed position of the movable panel is different in terms of inclination with respect to the rear bumper.

Nomenclature rear diffuser rear bumper mobile panel lower end of the mobile panel: first deployment rod: second deployment rod: first end of the first deployment rod: second end of the first deployment rod: actuator: first end of the second deployment link: second end of the second deployment link: connecting member: cylinder of the second link: pin of the first deployment link: upper end of the movable panel

Claims (13)

claims 1. Rear diffuser (2) of a motor vehicle characterized in that it comprises at least one movable panel (6) between a deployed position and a retracted position when the rear diffuser (2) is fixed to a bodywork part (4) motor vehicle, the rear diffuser (2) comprising a motorized mechanism capable of allowing a part of the movable panel (2) in the deployed position to press against the bodywork part (4) when the rear diffuser (2) is fixed on the bodywork part (4) of a motor vehicle. 2. Rear diffuser (2) according to the preceding claim, wherein the movable panel (6) is able to deploy and retract along a path in a combined movement of translation and rotation. 3. Rear diffuser (2) according to any one of the preceding claims, in which the motorized mechanism comprises two deployment connecting rods (10, 12). 4. Rear diffuser (2) according to claim 3, wherein the two deployment rods (10, 12) are linked to each other. 5. Rear diffuser (2) according to any one of claims 3 and 4, wherein the first deployment rod (10) is adapted to set in motion the second deployment rod (12). 6. Rear diffuser (2) according to the preceding claim, wherein the setting in motion of the second deployment rod (12) by the first deployment rod (10) is adapted to be achieved by means of a link (22) comprising a pin (26) linked to the first deployment link (10) and a cylinder (24) linked to the second deployment link (12). 7. Rear diffuser (2) according to the preceding claim, wherein the pin (26) and the cylinder (24) are pivotally mounted relative to each other. 8. Rear diffuser (2) according to any one of claims 6 and 7, wherein the cylinder (24) is slidably mounted along the second deployment rod (12), preferably via a connection sliding pivot type. 9. Rear diffuser (2) according to any one of claims 3 to 8, wherein the two deployment rods (10, 12) are adapted to be set in motion by an actuator (16) adapted to allow a movement of rectilinear actuation. 10. Rear diffuser (2) according to the preceding claim, wherein the actuator (16) is adapted to set in motion the first deployment rod (10). 11. Rear diffuser (2) according to any one of claims 9 and 10, in which the actuator (16) is chosen from a jack, a shape memory alloy actuator or a slide. 12. Motor vehicle body part comprising a rear diffuser (2) according to any one of the preceding claims. 13. Bodywork part according to the preceding claim, the bodywork part being a rear bumper (4) of a motor vehicle.