WO2013190223A1

WO2013190223A1 - Motorized drive device for vehicle seat

Info

Publication number: WO2013190223A1
Application number: PCT/FR2013/051404
Authority: WO
Inventors: Iman EL BEKKALI; Nicolas Navatte
Original assignee: Faurecia Sièges d'Automobile
Priority date: 2012-06-19
Filing date: 2013-06-14
Publication date: 2013-12-27
Also published as: FR2991926B1; DE112013003092T5; FR2991926A1; DE112013003092B4

Abstract

Motorized drive device for vehicle seat having a seat cushion (2) arranged on a base (1), the device comprising an output pinion (58) designed to drive the movement of a link rod (4a, 4b) connecting said seat cushion (2) to base (1), the device forming a drive module comprising a casing (10), a motor (6) having a rotor (61) able to rotate about an axis (A), reduction gearing (5) positioned between said rotor (61) and the output pinion (58), the motor being a piezoelectric motor (6). Articulation mechanism comprising such a drive device, a link rod (4a,4b) driven by the device and an elastic return member (95) applying a return torque to the link rod.

Description

MOTORIZED DRIVE DEVICE FOR VEHICLE SEAT

The present invention relates to motorized drive devices for a vehicle seat, said seat having a seat with a frame arranged on a base.

It particularly relates to a motorized drive device, here more particularly a drive module, comprising an output gear intended to cause the displacement of a movable element connected to the seat frame, so as to move up or down all or part of the seat relative to the base, or to move a portion of the seat relative to the frame, for example the seat nose.

In the prior art known, such a device comprises a DC motor type electric motor having a rotor rotatable about an axis A, and a gearbox disposed between said rotor and the output gear, the latter driving the rotation of such a movable element.

This type of driving device has operating noises that can be troublesome and the volume required to install the motor and the gearbox is important.

It has appeared necessary to reduce the operating noise and the bulk of such drive devices.

The invention proposes a drive module in which the motor is a piezoelectric motor. In addition, the module includes a housing that encloses the motor and the gearbox.

With these provisions, it can reduce the operating noise of such drive devices and they are easier to integrate because of their small footprint. In various embodiments of the invention, one or more of the following arrangements may also be used.

In one aspect, the motor rotor and the output gearwheel can both rotate about the same axis A; whereby the module is compact and can be easily installed on a seat frame;

In another aspect, the gear unit comprises a circular translation pinion engaged with a toothed wheel integral with the output pinion and comprises an oldham seal; whereby the reduction ratio of the reducer can be large and the offsetting of the orbital movement (or ^y of circular translation) can be compensated;

According to another aspect, the gearbox comprises a slider sliding in a base and intended to take forces exerted on the output gear in case of impact; whereby the device can withstand a large torque exerted on the output gear, for example in case of impact;

- The base can be fixed to a housing, the motor stator being fixed directly on said base; so that the axial dimension can be optimized, whereby the device can be very compact and can be easily installed on a seat frame;

In another aspect, the orbital pinion comprises projecting pins received in grooves of the slide; so that the forces exerted on the orbital gear in case of shock are transmitted to the slider and the housing.

In another aspect, the drive module may have a generally cylindrical shape and the axial length of the device excluding the output gear, and with an electronic control card included, may advantageously be less than 70 mm, so that the congestion is limited, whereby the device can be very compact and can be easily installed on a seat frame;

According to another solution, the reducer comprises a fixed flange comprising at least two pins projecting towards the orbital pinion, said orbital pinion comprising recesses receiving said pins and wider than the pins, to allow the orbital movement by preventing the rotation of the pinion orbital around the axis A; which is an alternative solution to the aforementioned slide;

In another aspect, the reducer may be a single-stage gearbox with oldham seal; which is an inexpensive solution and of optimized size;

In another aspect, the nominal rotational speed of the output gear can be less than 20 rpm; which makes it possible to deliver an advantageous pair;

In another aspect, the reducer may be a double planetary gearbox; which is a robust and well-known solution;

In another aspect, the housing comprises a bell-shaped body and a lid complementary to the body for closing the housing; which forms a compact module and easy to assemble

In another aspect, the casing has a generally cylindrical shape with a diameter of less than 100 mm; which facilitates its integration.

In addition, the invention also relates to a hinge mechanism comprising a drive device (or module) as described above, and a connecting rod forming said movable member driven by the device; the connecting rod is then in meshing relation with the driving device, for example by means of a toothed sector; whereby the movement of the connecting rod can raise or lower all or part of the seat relative to the base, and further reduction can be provided between the rotation of the output gear and the rotation of the rod; the connecting rod can also move the seat nose of the seat; the movable element could also be a rack to transform the rotation of the output gear into a translational motion.

According to another aspect of the invention, such a hinge mechanism may further comprise an elastic return member exerting a return torque on the connecting rod; by means of the elastic return member can compensate the gravity is exert a couple tending to raise all or part of the seat.

The invention also relates to a vehicle seat comprising a hinge mechanism as described above.

Other aspects, objects and advantages of the invention will appear on reading the following description of one of its embodiments, given by way of non-limiting example with the aid of the accompanying drawings, in which:

FIG. 1 is a partial schematic view of a seat structure comprising a driving device according to one embodiment of the invention; FIG. 2 shows a detail of the structure of the seat cushion of FIG. 1; ,

FIG. 3 is an exploded perspective view of the driving device of FIG. 1, seen from a first side,

FIG. 4 is an exploded perspective view of the driving device of FIG. 1, similar to FIG. 3, seen from the opposite side,

FIG. 5 is a cross section of the driving device of FIG. 1, along the line V-V of FIG. 6,

FIG. 6 is an axial section of the driving device of FIG. 1 along line VI-VI of FIG. figure 5,

- Figure 7 shows a variant on the 'oldham' seal of the reducer.

In the different figures, the same references designate identical or similar elements.

FIG. 1 schematically and partially shows a vehicle seat comprising a seat 2 with a seat frame 3, a backrest 19 mounted on the seat, the whole being mounted on a base 1 through one or more mechanisms of joint. This or these articulation mechanisms can be in particular a raising mechanism and / or one or two inclination mechanisms which can be obtained in particular but not exclusively via connecting rods (4a, 4b). For example for each of said connecting rods, the lower end is connected to the base 1 and the upper end is connected to the frame 3 of the seat 2 of the seat.

The seat frame 3 generally has a right side and a left side of similar architecture; in Figure 1, only one side is shown, and therefore, on the side not shown, there are other connecting rods between the seat and the base, equivalent to the connecting rods (4a, 4b) shown.

More specifically, in the illustrated example, a first link 4a connects the front portion 1a of the base 1 (pivoting shaft assembly referenced 11) to an anterior portion 3a of the armature 3 of the seat (pivoting mounting axis referenced 13), and a second rear link 4b, connects the rear portion 1p of the base 1 (pivoting shaft assembly referenced 12) to the rear portion 3p of the armature 3 (rotational axis mounting referenced 14 ). In the illustrated example, the pivoting assemblies of the first and second links (4a; 4b) are all axes parallel to the transverse axis Y which is perpendicular to the longitudinal axis X and perpendicular to the vertical axis Z (see Figure 1).

The seat of the seat can also optionally be equipped with a mobile seat nose, in height and / or in longitudinal extension. In the case of the seat nose inclination movement, an auxiliary connecting rod 75 connects the frame 3 to the seat nose, this auxiliary link being able to be set in motion by a driving device 4 via a toothed sector 76.

Furthermore, it can be provided that the base 1 is slidably mounted relative to the floor of the vehicle by means of longitudinal rails 90 comprising a fixed rail 90b fixed to the floor of the vehicle and a movable rail 90a integral with the base 1 aroused.

Of course the backrest 19 can be pivotally mounted relative to the seat 2 as is well known in the art.

The rods (4a; 4b) can be moved independently by respective control means or can be controlled simultaneously by synchronized control means or through a mechanical link (not shown) which can connect them.

When the first link 4a is turned counterclockwise by a driving device 4, then the front part 2a connected to the seat is lifted upwards, whereas conversely when the first connecting rod 4a is pivoted in the direction of the clockwise while the front portion 2a of the seat 2 is lowered to the floor. Similarly when the second connecting rod 4b is rotated in the counterclockwise direction (by another driving device 4) then the rear part 2p of the seat 2 is lifted upwards while when the second connecting rod 4b is pivoted in the clockwise the rear part 2p of the seat lowers towards the floor.

When the two connecting rods (4a, 4b) are ordered simultaneously, then the seat moves substantially parallel to the floor, which is called "raising" movement. When the first link 4a is controlled without the second link 4b moves, or vice versa, then we obtain a tilting movement of the seat. According to a provision shown schematically in Figure 1, the front articulation mechanism comprising the connecting rod 4a can be equipped with a return member 95 tending to rotate the rod in the trigonometric direction and exerting a couple upwards on the part front of the seat, so that the effects of gravity generated by the weight of the seat and / or the occupant installed on the seat can be at least partially offset by the effect of this return member 95.

A similar return member can of course be provided at the second connecting rod 4b.

This return member may be in a completely different form, for example a torsion bar which may advantageously be one of the transverse bars installed at the axes (11, 12, 13 or 14).

As illustrated in FIG. 2, the front link 4a (respectively the rear link 4b) is integrally connected to a transverse bar 35 extending along the transverse axis Y and connecting the connecting rod represented to an equivalent rod arranged on the other side of the seating structure (not shown). In addition, the rod 4a is integrally connected to a control flange 34 which is in the form of a metal plate extending in an X, Z plane. This control plate 34 is connected directly to the crossbar 35 and / or the connecting rod 4a and comprises on a substantially circular end sector a toothed zone 33 designed to cooperate with the motorized drive device 4 which comprises a output pinion 58 coming into direct drive with the toothed sector 33 mentioned above.

Preferably such a drive device 4 is arranged only on one side of the frame 3 of the seat cushion; the other side may be deprived of it. The output pinion 58 is arranged to rotate about an axis A substantially parallel to the transverse axis Y.

A protective casing 32 may be provided to partially or almost entirely cover the pinion 58 with the exception of the meshing zone in the toothed sector 33.

A second drive device, similar to the first, may be provided to similarly drive the rear link 4b.

With reference to FIGS. 3 to 6, the driving device 4 will now be described. It should first be noted that the (or the) drive device 4 previously mentioned is a module.

The latter comprises a casing 10 with a body 10a and a cover 10b, the body having a cylindrical bell-shaped shape with a bottom 88 and an annular wall 89, the cover 10b having the shape of a disk with an axial peripheral flange, this axial peripheral rim being fixed on the annular wall 89 of the body from the outside (see Figure 6). The lid 10b is made of metal and the body 10a can be made of metal or light alloy or plastic.

Inside the housing 10a are the two main elements of the drive module, namely a piezoelectric motor 6 and a gearbox 5 which are arranged coaxially one after the other on the axis A The piezoelectric motor 6 comprises a stator 62 in the general shape of a disk and a rotor 61 which is also in the form of a disk, for example thinner than the stator, and a piezoelectric ring 63 which presents the shape of a flat peripheral ring arranged in a plane transverse to the axis A.

A plurality of piezoelectric elements are arranged in the ring 63 and are connected by conductors 66 to an electronic control unit (not shown in the figures) which makes it possible to create progressive waves in the circumferential direction of this piezoelectric ring. 63. Said piezoelectric ring 63 is disposed against a peripheral zone 62c of the stator, in such a way that the waves generated by the piezoelectric elements are transformed into mechanical waves transmitted to the stator 62. Furthermore, an 'island' type washer 64 exerts an axial force to press the rotor 61 against the stator 62, so that the mechanical waves generated at the stator 62 are transformed into circumferential forces exerted on the rotor 61 to put it in motion around the axis A. An axially centered recess, marked 61e allows the rotor to transmit its rotational movement to a control shaft 7 equiped 7 complementary grooves of hollow shapes formed in the central axial recess 61e. There is thus obtained an electric motor known as the piezoelectric motor type which can generate a rotational movement on the rotor 61, for example in a range of speeds between 100 and 400 revolutions / min, for example 200 revolutions / min.

The rotational movement generated by this piezoelectric motor at the control shaft 7 is transmitted to the gearbox 5 which is downstream of the piezoelectric motor and whose output is in the form of the output pinion 58 already mentioned above.

More particularly, in the example of the reducer

5 illustrated here, the control shaft 7 drives an eccentric portion 70 received in an axial bore 53a of a pinion 53 called 'orbital'. Said orbital gear 53, under the effect of the rotation of the eccentric portion 70, sees its axis describe an orbital movement of a radius equivalent to the eccentricity of the eccentric portion, also called hypocycloid movement, or also called circular translation movement. Furthermore, the orbital pinion comprises an outer peripheral peripheral tooth zone 53b which is permanently engrained, for a part of the toothing, into a peripheral ring gear 56 located radially outside the orbital pinion 53. In addition, the orbital pinion 53 comprises axially projecting pins 21 and received in grooves 22 of a guide piece called slider 52 which will be detailed below.

Said slide 52 is arranged to be able to move in translation without rotational movement about the axis A therefore, the orbital gear 53 undergoes a movement around the axis A without turning around the axis A On the other hand, since the number of outer teeth of the orbital gear 53 is smaller than the number of teeth of the ring gear of a toothed inner radial zone 56, the orbital motion of the orbital gear 53 imparts a rotation to the ring gear 56. In the illustrated example where the difference between the number of teeth between two toothed sectors is one tooth, each time the eccentric portion 70 rotates by one turn, then the ring 56 is shifted by one tooth, rotation around the axis A. In the example illustrated here, the orbital gear comprises thirty-five teeth while the toothed sector of the crown 56 comprises thirty-six teeth, which gives a reduction ratio of 35 for the gearbox 5 .

The slider 52 is received in a base 51 which remains fixed relative to the housing 10 by means of four cylindrical feet 51a which are inserted into four corresponding holes 87 formed in the fixed cover 10b of the module.

The slider 52 comprises four arms 52a, 52b, 52c, 52d which extend in a plane perpendicular to the axis A and which are received in grooves 51b formed in the base 51 to allow a translational movement in the direction W perpendicular to the axis A and prevent any rotation of the slider 52 about the axis A. In addition, the slider 52 comprises the aforementioned grooves 22 extending according to the direction V perpendicular to the direction W and the axial direction A, and the orbital pinion 53 can translate in a direction V inside the slider, but without rotation around A; the slider 52 can translate with respect to the axis W in the base 51 but again without rotation around A. This assembly is also known as the seal of 'oldham'. Indeed, these two translations make it possible to compensate the orbital movement created by the eccentric portion 70 so that the movement of the output member 56 is exactly coaxial with the input rotational movement of the control shaft 7.

The principal elements that are the driving piezo electric ^¬ 6 and the gear 5 are complemented with auxiliary elements which are described below:

a shaft 8 which passes through the pinion 58, the ring 54 equipped with the toothed ring 56 and partially the control shaft 7, in the illustrated example the shaft 8 includes a pin end 80 which can be received in the protective casing 32 (see FIG.

a ball or roller bearing 91 mounted between a central bore 62a of the stator and a cylindrical pin of the control shaft 7,

a ring 93 on which the belleville washer 64, housed in an axial orifice 83 of the body 10a of the casing 10, rests,

an assembly screw 92 further equipped in the example of a washer 92b,

a smooth ring 86 interposed between the output gear 58 and the lid 10b of the housing. Immobilizing pins 62b protruding from the front face of the stator are received in orifices 51b of the base 51 to immobilize the stator 62 in rotation around the axis A.

Thus the stator 62 of the motor is fixed directly on the base 51 which itself is fixed to the housing 10a. The base 51 thus fulfills two functions, fixing the stator and guiding the slide 52, which makes it possible to optimize the axial dimension of the module.

It should be noted that the reduction ratio of the gearbox 5 could be between 10 and 50, while maintaining the same arrangement of the orbital gear 53.

According to one advantageous aspect, the gearbox 5 is a single stage gearbox as illustrated. However, it is not excluded in the context of the present invention to use a gearbox of another type, for example a double planetary gearbox. For example, it will be possible to use a gearbox such as for example described in the document FR2706380 or FR2614810.

According to an advantageous aspect, the nominal rotational speed of the output gear is less than 20 rpm, advantageously between 5 and 20 rpm.

In the event of shock to the vehicle, a significant force may be exerted on the rods 4a, 4b and therefore reflected at the output gear 58 of the device or drive module 4. Given the significant reduction ratio of the gearbox 5, and because the rotor 61 of the piezoelectric motor is braked in the absence of control by the belleville washer 64 which presses the rotor 61 against the stator 62, the torque exerted by the output pinion 58 is not reflected substantially to the rotor 61 but largely to the slider 52.

The slider 52 is designed to accommodate efforts directed along the axis V, W or mixed V, W the slider 52 is made of metal material for example steel, likewise, the base 51 takes the forces experienced by the slider 52 to transmit to the cover 10b of the housing; the base 51 is preferably made of metal but can also be made of hard plastic, for example ABS or polypropylene or other.

According to an advantageous aspect of the present invention, the drive module has a generally cylindrical shape, for example of diameter D less than 100 mm, preferably less than 90 mm, and the axial length E of the drive module without pinion of output is preferably less than 70 mm.

It should be noted that the casing is firmly fixed to the frame 3 of the seat; for example it may be provided to weld the cover 10a on the frame 3.

According to a variant illustrated in FIG. 7, the 'oldham' seal making it possible to compensate the eccentricity effect may be in a different form, the parts not described hereinafter being considered identical or similar to the preceding description.

In this variant, a flange 20 plays the role of both the base and the slide. This flange is secured to the housing 10, or is an integral part of the latter; the flange can be attached to any frame or external part via the fasteners 29.

The flange 20 comprises three nipples 23 (at least two are necessary) projecting towards the orbital gear 53 ', said orbital gear comprising recesses 24 receiving said nipples 23. These recesses 24 are wider than the nipples, to allow the movement orbital induced by the eccentricity of the orbital movement, while preventing the rotation of the orbital pinion 53 'about the axis A. The orbital motion of the pinion 53' leads as described above the output member with an exact coaxiality on the axis A. The electronic control unit which controls the elements of the piezoelectric ring 63 may be arranged inside the housing 10, for example on a card formed in disk pierced in the middle. It can also be arranged outside the housing, close to it.

Claims

A vehicle seat drive module, the module comprising:

an output gear (58) intended to cause the displacement of a movable element (4a, 4b, 75) connected to a seat cushion frame,

a housing (10) enclosing:

a piezoelectric motor (6) having a rotor (61) rotatable about an axis (A),

a gearbox (5) disposed between said rotor (61) and the output gear (58).

2. Drive module according to claim 1, wherein the rotor (61) of the motor (6) and the output gear

(58) are configured to both rotate about the same axis (A).

3. Drive module according to one of claims 1 to 2, wherein the housing has a generally cylindrical shape and the axial length (E) of the housing is less than 70 mm.

4. Drive module according to one of claims 1 to 3, wherein the reduction ratio of the gearbox is between 10 and 50, and wherein the nominal speed of rotation of the piezoelectric motor is less than 400 revolutions / min.

5. Drive module according to one of claims 1 to 4, wherein the housing (10) comprises a body (10a) shaped bell and a cover (10b) complementary to the body to close the housing.

6. Drive unit according to one of claims 1 to 5, wherein the reducer is a single-stage gearbox with oldham seal.

7. Drive module according to one of claims 1 to 5, wherein the gearbox is a double planetary gear.

8. Drive module according to one of claims 1 to 6, wherein the reducer comprises a slide (52) sliding in a base (51), said slide being adapted to take up forces exerted on the output pinion in case of shock, the base (51) being fixed to the housing (10), the stator (62) of the motor being fixed directly on said base.

9. Drive module according to one of claims 1 to 8, wherein the housing has a generally cylindrical shape of diameter (D) less than 100 mm.

10. Drive module according to one of claims 1 to 9, wherein the housing further comprises an electronic control unit.

11. Adjustment mechanism comprising a drive module according to one of claims 1 to 10 and a movable member belonging to the frame (3) seat, wherein the output gear (58) is intended to cause the displacement a connecting rod (4a, 4b, 75) forming said movable member driven by the module.

12. Seat for a motor vehicle comprising a drive module according to one of claims 1 to 10, or a hinge mechanism according to claim 11.