TITLE: Corrector with electric motor and mechanical stops for motor vehicle headlamp.

TECHNICAL FIELD

This invention relates to a corrector with electric motor and mechanical stops for a motor vehicle headlamp.

BACKGROUND

Traditionally, a motor vehicle headlamp generally comprises at least one light source placed in front of an optical reflector. A light beam emitted by the light source is projected outside the motor vehicle at the front or at the rear. More specifically, the reflector has the function of directing the light beam.

In order to change the position of the reflector and thus direct the light beam, a corrector is used. Usually, a corrector is equipped with a rod, one end of which is connected to the reflector, and an electric motor, the operation of which is controlled by a control unit. Generally, the electric motor rotates in one direction or the other. These rotational movements are converted, by a mechanical device, into a longitudinal movement of the rod in one direction or the other. Such a movement causes the reflector to swivel, which changes the orientation of the light beam. In addition, a metering device is used to measure a quantity associated with the rotations of the electric motor, for example, the number of revolutions made during its use. This quantity is therefore also representative of the relative distance travelled by the rod during its rectilinear movement between the start and stop of the electric motor.

However, such a corrector does not take into account a reference position for each new use of the motor. The metering of the number of revolutions, for example, therefore, does not allow the definition of the current position of the rod, which is linked to the reflector, after each use. However, without defining the current position of the rod between two uses of the motor, it is not possible to know the exact orientation of the light beam.

This solution is therefore not satisfactory.

DISCLOSURE OF THE INVENTION

The purpose of this invention is to remedy this disadvantage.

It relates to a corrector for motor vehicle headlamps.

According to the invention, the corrector comprises:

- a housing provided with a rod and an electromechanical assembly capable of generating a longitudinal displacement of the rod, the electromechanical assembly comprising an electric motor capable of generating a rotational movement and a mechanical device capable of transforming the rotational movement of the electric motor into a longitudinal displacement of the rod;

- two mechanical stops, each of the mechanical stops being formed by at least one stop element arranged on the rod and cooperating with at least one limit stop, each of the mechanical stops defining a reference position of the rod; and

- a metering device configured to measure data values associated with the rotational movements of the electric motor and representative of the distance travelled by the rod during its longitudinal displacement with respect to one of the reference positions, the reference positions defining the maximum distance that can be travelled by the rod, in which the mechanical device includes:

-a worm screw attached to the electric motor; and

-a drive shaft that engages with the rod for causing the longitudinal displacement of the rod, in which a rotation axis of the worm screw runs parallel to a rotation axis of the electric motor, and

-an auxiliary screw that is arranged such that its rotation axis runs transversally to the rotation axes of the drive shaft and the rod, the auxiliary screw having a gearing cogging with the worm screw and a thread cogging with a gearing of the drive shaft; the drive shaft further comprising a helical thread that engages with the rod such that rotational movements of the worm screw are transformed into longitudinal displacement of the rod.

Thus, thanks to the invention, the mechanical stops define reference positions of the longitudinal rod, allowing its exact current position to be determined each time the electric motor is used. Such a set-up is advantageous since it is insensitive, i.e. not prone to jam in an end position, e.g. if the climatic conditions change in which the corrector is used.

Advantageously, the electric motor is a direct current motor, the rotational movements of which generate a succession of current peaks, the number of successive peaks generated representing one of the data values measured by the metering device.

Preferably, the worm screw comprising a thread and a first end attached to the electric motor, the worm screw being subjected to the rotational movements generated by the electric motor. In a first embodiment, each of the limit stops provided on the drive shaft (10) is formed by a plane perpendicular to the thread of the drive shaft, the plane being associated with one end of the thread of the drive shaft.

Advantageously, in this first embodiment, a stop element is formed by a protuberance arranged on an internal face of the rod engaging in the helical threat.

In a second embodiment, each of the limit stops is arranged at one end of an internal face of the housing.

Preferably, in this second embodiment, each of the stop elements is arranged at one end of a peripheral face of the rod.

Advantageously, the auxiliary screw being capable of transmitting the rotational movements of the worm screw to the drive shaft.

This invention furthermore relates to a motor vehicle headlamp, which is provided with a corrector such as that described above. BRIEF DESCRIPTION OF THE FIGURES

The attached figures will make it clear how the invention can be realized. In these figures, identical references designate similar elements.

[Fig. 1] Fig. 1 schematically illustrates a headlamp corrector according to one embodiment.

[Fig. 2a-2b] Fig. 2a and Fig. 2b schematically show cross-sections of the headlamp corrector in two different positions according to a first embodiment. [Fig. 3a-3b] Figs. 3a and Fig. 3b schematically illustrate cross-sections of the headlamp corrector with a rod in two different positions according to a second embodiment.

[Fig. 4a-4b] Fig. 4a and Fig. 4b schematically represent elements of a headlamp corrector housing in the first embodiment.

[Fig. 5] Fig. 5 schematically illustrates a worm screw that is part of the headlamp corrector.

[Fig. 6] Fig. 6 schematically illustrates an auxiliary screw that is part of the headlamp corrector.

[Fig. 7] Fig. 7 schematically illustrates a drive shaft that is part of the headlamp corrector according to the second embodiment.

DETAILED DESCRIPTION

The motor vehicle headlamp corrector 1, which is used to illustrate the invention and is shown schematically in Fig. 1, is intended to change the position of a reflector arranged inside a headlamp.

In the context of the invention, corrector 1 comprises, as shown in figure 1, a housing 2. This housing 2 is provided with a rod 3 and an electromechanical assembly 4 capable of generating a longitudinal displacement of the rod 3. As shown in Fig. 2a and Fig. 3a, the electromechanical assembly 4 comprises an electric motor 5 configured to generate rotational movements and a mechanical device 6 configured to transform the rotational movements of motor 5 into longitudinal displacement of rod 3.

Moreover, the corrector 1 comprises two mechanical stops 19. These mechanical stops 19 are formed out of one or more stop elements arranged on rod 3, each of which cooperates with one or more limit stops 19A. These mechanical stops 19 define a reference position P1 , P2 of rod 3.

For the purposes of the invention, reference positions P1, P2 are understood to be the positions of rod 3 defining the maximum distance that rod 3 can travel during a longitudinal movement.

In addition, corrector 1 comprises a metering device (not shown) which is configured to measure data values associated with the rotations of motor 5. These data are representative of the distance travelled by rod 3 during its longitudinal movement with respect to at least one of the reference positions P1, P2.

In the rest of the description, and as shown in Fig. 2a, Fig. 2b, Fig. 3a and Fig. 3b, two orthogonal axes associated with corrector 1 are used, namely a so- called longitudinal X-X axis which is oriented along rod 3, and a transverse Y- Y axis which defines, with the longitudinal X-X axis, a longitudinal X-Y plane. Moreover, the adjectives "upper" and "lower" in relation to corrector 1 are respectively defined according to the direction of an arrow F and the direction opposite to that of the arrow F. In addition, the adjectives "front" and "back" in relation to corrector 1 are respectively defined according to the direction of an arrow G and the direction opposite to that of arrow G. Furthermore, the adjectives "internal" and "peripheral" in relation to corrector 1 are defined according to the radial direction in relation to the longitudinal X-X axis, respectively towards the inside of rod 3 and towards the outside of rod 3.

As shown in Fig. 4a and Fig. 4b, the housing 2 comprises a first and a second element 2A and 2B, each arranged in a plane parallel to the longitudinal X-Y plane. The elements 2A and 2B are capable of being interlocked with each other. A gasket 7 is arranged around the front part of elements 2A and 2B of corrector 1, as shown in Figure 1. This gasket 7 is configured to keep corrector 1 watertight. Moreover, the housing 2 forms an internal space comprising several compartments C1, C2, C3 in which the rod 3 and the electromechanical assembly 4 are arranged.

As shown in Fig. 2b and Fig. 3b, rod 3 is formed by a hollow cylindrical body 3A arranged along the longitudinal X-X axis in an upper front compartment C1 of housing 2. The hollow cylindrical body 3A is provided with an internal and a peripheral face. In addition, rod 3 has a sphere 3B which is attached to a front end of the cylindrical body 3A. In addition, rod 3 has a rear end 3C, which is opposite to the sphere 3B. As shown in Fig. 1 , the sphere 3B is arranged on the outside of the housing 2. The rod 3 is capable of moving along the longitudinal X-X axis, towards the front of the corrector 1 in the direction of arrow G or towards the back of the corrector 1 in the direction opposite to that of arrow G. The longitudinal displacement of the rod 3 generates a change in the orientation of the reflector which is linked to the sphere 3B (not shown). Moreover, the electromechanical assembly 4 comprises a motor 5 which is arranged in a lower compartment C2 in front of corrector 1 , as shown in Fig. 2b and Fig. 3b, motor 5 is capable of receiving a control command. This control command can be a run command or a stop command. If a run command is received, motor 5 is configured to generate rotational movements about an A-A axis, parallel to the longitudinal X-X axis. These rotational movements can take place in a direction represented by the arrow R1 or in the opposite direction.

In one embodiment, motor 5 is a brush-type DC electric motor. It is supplied with a stator provided with magnets, a rotor provided with a winding, a shaft, a commutator and a plurality of brushes (not shown). The brushes are connected to a direct current generator. Depending on the polarity of the current supplied by the generator, motor 5 generates rotational movements of the shaft in the direction of arrow R1 or in the opposite direction. These rotational movements generate a succession of commutations of the brushes on the commutator. Each commutation causes a rapid change in the resistance of motor 5 which is associated with a current peak. The number of successive commutations is represented by a number of current peaks. Moreover, as shown in Fig. 2b and Fig. 3b, the electromechanical assembly 4 also comprises the mechanical device 6 which is attached, on the one hand, to motor 5 and, on the other hand, to rod 3. This mechanical device 6 is configured to transform the rotational movements of motor 5 into longitudinal displacement of rod 3.

In one embodiment, the mechanical device 6 comprises a worm screw 8. As shown in Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b and Fig. 5, the worm screw 8 is arranged along the A-A axis in the lower part of a rear compartment C3 of housing 2. The worm screw is located in the extension of the shaft of motor 5 to which it is attached by an end 8A. In one embodiment, the end 8A of the worm screw 8 is attached to the shaft of motor 5 by means of a forced press fit. The worm screw 8 is subjected to the rotational movements generated by motor 5 about the A-A axis in the direction of the arrow R1 or in the opposite direction. Moreover, worm screw 8 is provided with a thread 8B extending over its entire length.

In one embodiment shown in Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b and Fig. 6, the mechanical device 6 also comprises an auxiliary screw 9 which is arranged along the transverse Y-Y axis in compartment C3. The auxiliary screw is provided with a thread 9A on an upper part, a gearing 9B on a lower part and a solid cylinder 9C between thread 9A and gearing 9B.

In the context of the invention, gearing 9B means a succession of teeth 20, preferably rectilinear, arranged parallel to one another and radially distributed on the peripheral face of the auxiliary screw 9 or of a drive shaft 10. Moreover, the orientation of the successive teeth 20 of the auxiliary screw 9 is such that the teeth form a non-zero angle with the transverse Y-Y axis, as shown in Fig. 6.

In one embodiment, the gearing 9B of auxiliary screw 9 is shaped to cooperate with the thread 8B of worm screw 8. The cooperation between thread 8B and gearing 9B allows the transmission of rotational movements from worm screw 8 to auxiliary screw 9.

Moreover, as shown in Fig. 6, auxiliary screw 9 is capable of executing rotational movements about the transverse Y-Y axis in the direction of arrow R2 or in the opposite direction. In addition, the solid cylinder 9C forms, together with the housing 2, a swiveling connection that allows rotational movements about the transverse Y-Y axis, but blocks any translational movement of auxiliary screw 9 along the same transverse Y-Y axis.

In one embodiment, the mechanical device 6 also includes a drive shaft 10. As shown in Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b and Fig. 7, drive shaft 10 is arranged along the longitudinal X-X axis, perpendicular to auxiliary screw 9. It is arranged straddling compartments C1 and C3.

Moreover, the drive shaft 10 is able to rotate about the longitudinal X-X axis in the direction of arrow R3 or in the direction opposite to that of arrow R3. The drive shaft is provided with a gearing 10A in its rear part, as shown in Fig. 6. The gearing 10A of the drive shaft 10 is shaped to match the thread 9A of the auxiliary screw 9 with which it cooperates to transmit the rotational movements of the auxiliary screw 9, about the transverse Y-Y axis, to the drive shaft 10 about the longitudinal X-X axis.

Moreover, drive shaft 10 is provided with a thread 10B. A rear end of the thread 10B is formed by a flange collar 11 arranged in a plane perpendicular to the longitudinal X-X axis. In addition, the diameter of flange collar 11 is larger than the diameter of the auxiliary screw 9.

Moreover, a front end of the gearing 10A of drive shaft 10 is formed by a flange collar 12 arranged in a plane perpendicular to the longitudinal X-X axis. The diameter of flange collar 12 is larger than the diameter of drive shaft 10. Protrusions of the housing 2 are arranged in the space between the two flange collars 11 and 12 without being in contact with the drive shaft 10 (not shown). Together with flange collars 11 and 12, they form a swivel connection. This swivel connection allows rotational movements of the drive shaft 10 about the longitudinal X-X axis and blocks translational movements of the drive shaft 10 along the same longitudinal X-X axis.

In one embodiment, the thread 10B of drive shaft 10 is able to be engaged in the hollow cylindrical body 3A of rod 3 with which it forms a helical connection. The helical connection makes it possible to convert the rotational movement of the drive shaft 10 about the longitudinal X-X axis in the direction of arrow R3, or in the opposite direction, into a translational movement of the rod 3 along the longitudinal X-X axis in the direction of arrow G or in the opposite direction.

In one embodiment, corrector 1 comprises two mechanical stops 19. A first mechanical stop 19 defines a so-called distal reference position P1 of rod 3 (hereinafter referred to as the distal reference position P1), as shown in Fig. 2a and Fig. 3a. A second mechanical stop 19 defines a so-called proximal reference position P2 of rod 3 (hereinafter referred to as the proximal reference position P2), as shown in Fig. 2b and Fig. 3b.

For the purposes of the invention, a distal reference position P1 is understood to be the reference position P1 of rod 3 in which the sphere 3B of rod 3 is furthest away from corrector 1 in the direction of G. A proximal reference position P2 is understood to be the reference position P2 of rod 3 in which the sphere 3B of rod 3 is closest to corrector 1 in the direction of G.

Each of the mechanical stops 19 of corrector 1 has one or more stop elements attached to rod 3 and one or more limit stops 19A. The limit stops 19A are shaped to cooperate with the stop elements of rod 3 to block the longitudinal movement of rod 3 in a particular direction.

In a first embodiment shown in Fig. 2a, Fig. 2b, Fig. 4a and Fig. 4b, the mechanical stops are so-called axial stops (hereinafter "axial stops"). The stop elements are arranged at the rear end 3C of a peripheral face of rod 3. They consist of protruding elements (not shown). Alternatively, the stop elements correspond to a ring arranged on the peripheral face of the rod 3 about the longitudinal X-X axis. As shown in Fig. 4a and Fig. 4b, the limit stops are arranged on the internal face of compartment C3 of housing 2. This internal face comprises part of the internal face of element 2A (hereinafter "first internal face 13") and part of the internal face of element 2B (hereinafter "second internal face 14").

In this first embodiment, the limit stops correspond to lugs 15 attached to the front end and lugs 16 attached to the rear end of the first internal face 13, along the longitudinal X-X axis and the transverse Y-Y axis. As an example, the number of lugs 15, 16 is equal to four. The limit stops also correspond to lugs 17 attached to the rear end of the second internal face 14 and to a bar 18 attached to the front end of the second internal face 14. Bar 18 is arranged along an axis parallel to the transverse Y-Y axis. The length of bar 18 is substantially equal to the diameter of rod 3.

Moreover, the number of stop elements is equal to the number of limit stops 19A arranged at the rear end of the first and second internal faces 13 and 14. In one variant, the limit stops 19A attached on the second internal face 14 are exclusively lugs 17. In another variant, the limit stops 19A are arranged on the internal side 13, 14 of only one of the elements 2A or 2B.

Moreover, in this first embodiment, the axial stops are configured to block the longitudinal movement of rod 3 in the direction of arrow G, when the stop elements come into contact with bar 18 and with lugs 15. Rod 3 is then in the distal reference position P1, as shown in Fig. 2a.

The axial stops are also to configured block the longitudinal movement of pin 3 in the direction opposite to the direction of arrow G, when the stop elements are in contact with lugs 16 and 17. Rod 3 is then in the proximal reference position P2, as shown in Fig. 2b.

In a second embodiment, shown in Fig. 3a, Fig. 3b and Fig. 7, the mechanical stops are called radial (hereafter "radial stops"). The limit stops 19A are arranged on the thread 10B of the drive shaft 10, as shown in Fig. 7, and the stop element (not shown) is arranged on the internal face of the rod 3. Each of the limit stops 19A has a plane S1, S2 perpendicular to the thread 10B of the drive shaft 10. The planes S1 , S2 correspond respectively to a front end and a rear end of the thread 10B.

The stop element is formed by a protrusion on the internal side of the rod 3. In one embodiment, the internal face of the rod 3 is provided with a female thread. The protuberance corresponds with one end of the female threading arranged at the back of the rod 3.

In this second embodiment, the radial stops are configured to block the movement of rod 3 in the direction of arrow G or in the direction opposite to arrow G. When the planeSI and the protrusion are in contact, the helical connection is blocked. The rod 3 is then in the distal reference position P1 (see Fig. 3a). The cooperation between the planeS2 and the protrusion blocks the helical connection. Rod 3 is then in the proximal reference position P2 (see Fig. 3b). In this second embodiment, the first and second internal surfaces 13 and 14 of elements 2A and 2B of housing 2 do not have limit stops 19A.

In one embodiment, corrector 1 comprises a metering device (not shown). This metering device is configured to measure data values that are associated with the rotations generated by motor 5 during operation. In one embodiment, motor 5 is a brush-type DC motor. One of the data values corresponds to the number of successive current peaks generated by the commutations of the brushes on the commutator. The number of peaks is representative of the distance travelled by the rod 3 during its longitudinal movement in relation to a reference position P1, P2.

The conditions of use of corrector 1 are explained below.

Usually, motor 5 receives a control command. When the control command corresponds to a run command, motor 5 generates rotational movements. In one embodiment, the run command includes information on the direction in which motor 5 should rotate. The rotational movements are carried out either in the direction of arrow R1 or in the direction opposite to arrow R1. In the case of a brush-type DC motor 5, the rotational movements of motor 5 cause successive commutations of the brushes with the commutator. The metering device then measures the number of current peaks generated by the successive commutations during operation of motor 5.

The rotational movements are transmitted to the worm screw 8 to which motor 5 is attached. The worm screw 8 rotates about the A-A axis in the same direction as the shaft of motor 5. The thread 8B of worm screw 8 cooperates with the gearing 9B of auxiliary screw 9 and subjects auxiliary screw 9 to rotational movements. As the auxiliary screw 9 is arranged perpendicular to the worm screw 8 along the transverse Y-Y axis, the rotational movements are carried out in the direction of the arrow R2 or in the opposite direction. As shown in Fig. 2a, Fig. 2b, Fig. 3a and Fig. 3b, when the worm screw 8 performs rotational movements according to arrow R1, the auxiliary screw 9 performs rotational movements according to arrow R2.

The thread 9A of the auxiliary screw 9 cooperates with the gearing 10A of the drive shaft 10 so that the rotational movements of the auxiliary screw 9 are transmitted to the drive shaft 10. The drive shaft 10 then performs rotational movements about the longitudinal X-X axis in the direction of arrow R3 or in the opposite direction. As shown in Fig. 2a, Fig. 2b, Fig. 3a and Fig. 3b, the rotational movements of the auxiliary screw 9 in the direction of arrow R2 are transformed into rotational movements of the drive shaft 10 in the direction of arrow R3.

Drive shaft 10, which is formed of a threaded part 10B engaged in the hollow cylindrical body 3A, forms a helical connection with rod 3. As shown in Fig. 2a, Fig. 2b, Fig. 3a and Fig. 3b, the helical connection transforms the rotation of the drive shaft 10 in the direction of arrow R3, or respectively in the direction opposite to that of arrow R3, into a longitudinal movement in the direction of arrow G, or respectively in the direction opposite to that of arrow G.

The rod 3 can travel a maximum distance along the longitudinal X-X axis. This maximum distance is defined by the reference positions P1, P2.

In the first embodiment, rotation of the drive shaft 10 in the direction of arrow R3 drives rod 3 to move longitudinally in the direction of arrow G until the lugs of rod 3 come into contact with lugs 15 or part of bar 18 which form the limit stops 19A. Rod 3 can no longer move in the direction of arrow G and is in the distal reference position P1, as shown in Fig. 2a. In the second embodiment, the longitudinal movement of rod 3 is blocked when the protrusion on the internal face of rod 3 comes into contact with the planeSI which represents the front end of thread 10A of drive shaft 10 (Fig. 2a and Fig. 7).

Moreover, rotation of the drive shaft 10 in the direction opposite to that of arrow R3 brings about the longitudinal displacement of rod 3 in the direction opposite to that of arrow G, until reaching the reference position P2 proximal to rod 3 (Fig. 2b).

In the first embodiment, the protruding elements (not shown) that are arranged on the rear end 3C of the peripheral face of rod 3 move until they come into contact with lugs 16 and 17 that are arranged at the rear end of the first and second internal faces 13 and 14.

In the second embodiment, the contact between the protrusion of the internal face of the rod 3 with the planeS2 which corresponds to the rear end of the thread 10A of the drive shaft 10 blocks the longitudinal movement of the rod 3 in the direction opposite to that of arrow G. The rod 3 is in the proximal reference position P2, as shown in Fig. 3b.

Furthermore, the corrector 1 allows the definition of reference positions P1 and P2, from which the current position of rod 3 along the longitudinal X-X axis can be determined. This current position defines the orientation of the reflector.

During operation of motor 5, the metering device measures data values representative of the rotations of motor 5. In an embodiment where motor 5 is a brush-type DC motor, the values of these data correspond to the number of current peaks generated by the commutations of the brushes on the commutator. The rotational movements of motor 5 are transformed into translational movements of rod 3 by the mechanical device 6. Thus, the number of current peaks is proportional to the distance travelled by rod 3. When the corrector 1 is initialized, rod 3 is arranged in a reference position P1 , P2. As long as motor 5 is running, rod 3 moves longitudinally. When motor 5 stops, the metering device determines the current position of rod 3. When used at a later time, the metering device associates the previous current position with the new distance travelled by rod 3 between the reference positions P1 and P2.