Method for minimizing noise generated by the motorized adjustment of the position of a moving part of a motor vehicle seat headrest

Abstract

The invention relates to a method for minimizing the noise generated by adjusting the position of a movable part (1a, 1b) of a headrest (2) of a motor vehicle seat, said headrest comprising a motorized actuation device for said movable part towards an adjustment position and at least one sound transmission device (5), said method providing a programmable system for controlling said motor which is further programmable to generate a signal to said sound transmission device, said method comprising the following steps: an initial calibration of said system to memorize at least one reference sound spectrum of the actuation device for raising and lowering said movable part; in the situation of adjustment of said movable part, the emission by the sound transmission device (5) of a phase-shifted sound signal adjusted in amplitude so as to attenuate or eliminate the noise corresponding to said reference sound spectrum. Figure 1

Description

Title of the invention: Method for minimizing the noise generated by the motorized adjustment of the position of a movable part of a vehicle seat headrest

[0001] The invention relates to a method for minimizing the noise generated by the motorized adjustment of the position of a movable part of a headrest in a motor vehicle seat. The invention also relates to a headrest equipped with a movable part whose adjustment noise is minimized by such a method.

[0002] It is known to produce a motor vehicle seat headrest, said headrest comprising: • a fixed part intended to be attached to the top of the backrest of said seat, • a movable part intended to support the head of an occupant of said seat, said movable part being detachable relative to said fixed part so as to be adjustable according to the morphology of said occupant, • a device for actuating said moving part to an adjustment position, said device comprising an electric motor, • at least one sound transmission device, used in particular to transmit information or music.

[0003] It is also known to provide the seat with a programmable system for controlling the electric motor, said system usually being located in the headrest or under the seat of said seat.

[0004] The position of the moving part is adjusted in particular by the occupant operating a control.

[0005] Alternatively, the possibility of memorizing the characteristics of an occupant can be provided to simplify adjustment. Since the control system identifies the positions of the moving part, a personalized adjustment of said moving part is performed according to a plurality of memorized positions corresponding to as many respective occupants.

[0006] With such an arrangement, implementing a motorized adjustment of the moving part, noise is generated related to the operation of the actuation device of said moving part.

[0007] The invention aims to overcome this drawback.

[0008] To this end, and according to a first aspect, the invention proposes a method for minimizing the noise generated by adjusting the position of a movable part of a motor vehicle seat headrest, said headrest comprising: • a fixed part intended to be attached to the top of the backrest of said seat, • said movable part intended to support the head of an occupant of said seat seat, said movable part being detachable relative to said fixed part so as to be adjustable according to the morphology of said occupant, • a device for actuating said moving part to an adjustment position, said device comprising an electric motor, • at least one sound transmission device,

[0009] said method comprising a programmable control system for said motor which is further programmable to generate a signal to said sound transmission device, said method comprising the following steps: • an initial calibration of said system to memorize at least one reference sound spectrum of the actuation device during the upward and downward movement of said moving part, • in the situation of adjusting said moving part, the emission by the sound transmission device of a sound signal that is out of phase and adjusted in amplitude so as to attenuate or eliminate the noise corresponding to said reference sound spectrum.

[0010] In this description, the terms of positioning in space (longitudinal, vertical, superior,...) are taken with reference to the vehicle in which the headrest to be adjusted is located, said vehicle extending longitudinally along its length (along an X axis) and vertically along its height (along a Z axis).

[0011] With the proposed arrangement, the motor control system is further programmed to generate a signal to the sound transmission device, said signal being phase-shifted and adjusted in amplitude so as to attenuate or eliminate the noise corresponding to the reference sound spectrum.

[0012] We thus take advantage of the presence of the control system and the sound transmission device to program said system with an "anti-noise" function.

[0013] According to a second aspect, the invention proposes a headrest provided with a movable part whose adjustment noise is minimized by such a method.

[0014] Other features and advantages of the invention will become apparent from the following description, made with reference to the accompanying figures, in which:

[0015] [Fig-1] is a partial schematic perspective representation of a headrest according to one embodiment, said headrest being provided with two movable parts whose noise generated by their adjustment can be minimized by a method according to the invention,

[0016] [Fig.2] is a schematic representation of the principle of detail of the headrest re shown in figure, in order to illustrate the actuation device of its moving parts, only one motor being represented.

[0017] With reference to the figures, a method for minimizing the noise generated by adjusting the position of a movable part la,lb of a headrest 2 of a motor vehicle seat is described, said headrest comprising: • a fixed part 3 - here in the form of two parallel metal rods 8 connected to each other by a spacer 9 extending between the upper ends of said rods - intended to be attached to the top of a backrest of said seat, • said movable part intended to support the head of an occupant of said seat, said movable part being movable relative to said fixed part so as to be adjustable according to the morphology of said occupant, • a device for actuating said moving part to an adjustment position, said device comprising an electric motor 4, • at least one - two depending on the embodiment represented - sound transmission device 5,

[0018] said method comprising a programmable control system for said motor which is further programmable to generate a signal to said sound transmission device, said method comprising the following steps: • an initial calibration of said system to memorize at least one reference sound spectrum of the actuation device during the upward and downward movement of said moving part, • in a situation of adjusting said moving part, the emission by the sound transmission device of a sound signal that is out of phase and adjusted in amplitude so as to attenuate or eliminate the noise corresponding to said reference sound spectrum.

[0019] It is specified here that, in order to define with relevance the phase-shifted and amplitude-adjusted sound signals, the reference sound spectra are processed by means of an algorithm which allows in particular to filter and amplify them.

[0020] Next, an anti-noise algorithm is applied by an appropriate technique, for example an adaptive filtering technique (Least Mean Squares (LMS) or Recursive Least Squares (RLS)).

[0021] The phase-shifted signals are then stored in a memory card integrated into an electronic card.

[0022] A program stored in a non-volatile memory (Read Only Memory (ROM)) of the card finally synchronizes the out-of-phase signals with the movements of the electric motor 4.

[0023] A sound transmission device 5 may in particular be in the form of a loudspeaker or a transducer with a smaller size and weight.

[0024] It is recalled here that a transducer differs from a loudspeaker in the following way: • A loudspeaker comprises a magnet fixedly mounted on a support and a flexible diaphragm attached to a voice coil, said diaphragm entering

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[0031] vibration when the speaker is powered on, • a transducer includes a coil fixedly mounted on a rigid plate and a magnet fixed to a block mounted by means of a suspension on said coil, so that said plate vibrates when said transducer is powered. A plurality of reference spectra can be predicted depending on the position of the moving part, in particular when the movement of said moving part is carried out at a constant speed except when it reaches the end of its travel against a stop, the control system then controlling - for example by the "Techno Ripple Count" technology - a progressive decrease in the speed of said moving part until said stop. Such an arrangement makes it possible to gradually reduce the speed of the moving part at the end of its travel and to avoid sudden jolts that could damage its actuation device. It is specified here that a reference spectrum is measured in particular near the position of a passenger's ears, in order to optimize the minimization of noise pollution. According to one implementation, the initial calibration is carried out in a standardized manner for a model of headrest 2 intended to equip a range of vehicles. According to an alternative embodiment, the initial calibration is carried out specifically for each headrest 2 fitted to a given vehicle, at the end of production of said vehicle. We now describe a programmable headrest 2 using such a method, said headrest comprising: • a fixed part 3 intended to be attached to the top of a backrest of said seat, • a movable part la,lb designed to support the head of an occupant said seat, said movable part being detachable relative to said fixed part so as to be adjustable according to the morphology of said occupant, • a device for actuating said moving part to an adjustment position, said device comprising an electric motor 4, • at least one sound transmission device 5, • a programmable control system for said motor, said system being further programmable to generate a signal to said sound transmission device, so as to attenuate or eliminate the adjustment noise of said moving part. The integration of the programmable system into the headrest 2 allows for a fully equipped headrest, unlike the case where the system is mounted under the seat of the seat equipped with the headrest.

[0032] According to the embodiment shown, a moving part is a main moving part adjustable about a vertical axis Z, the actuation device of said main moving part comprising, in addition to the motor 4: • a worm screw 6a extending vertically (along the Z axis), said screw being mounted for rotation on said main moving part, said screw being driven in rotation by said motor also mounted on said main moving part, • a nut 7a mounted on the fixed part, said screw cooperating with said nut so as to allow movement of said main moving part by rotating said screw.

[0033] According to the embodiment shown, the headrest 2 further comprises a secondary movable part 1b adjustable about a longitudinal axis X, said secondary movable part being slidably mounted on the main movable part la, the actuation device of said secondary movable part comprising, in addition to the motor 4: • a worm screw 6b extending longitudinally (about the axis X), said screw being rotatably mounted on said main movable part, said screw being rotatably actuated by said motor also mounted on said main movable part, • a nut 7b mounted on said secondary moving part, said screw cooperating with said nut so as to allow movement of said secondary moving part by rotating said screw.

Claims

Claims

1. Method for minimizing the noise generated by adjusting the position of a movable part (la, lb) of a headrest (2) of a motor vehicle seat, said headrest comprising: • a fixed part (3) intended to be associated with the top of a backrest of said seat, • said movable part intended to receive the head of an occupant of said seat, said movable part being movable relative to said fixed part so as to be able to be adjusted according to the morphology of said occupant, • a device for actuating said movable part towards an adjustment position, said device comprising an electric motor (4), • at least one sound transmission device (5), said method providing a programmable system for controlling said motor which is further programmable to generate a signal to said sound transmission device,said method comprising the following steps: • an initial calibration of said system to memorize at least one reference sound spectrum of the device for actuating up and down said moving part, • in a situation of adjustment of said moving part, the emission by the sound transmission device (5) of a phase-shifted sound signal adjusted in amplitude so as to attenuate or eliminate the noise corresponding to said reference sound spectrum.,

2. Method according to claim 1, characterized in that the initial calibration is carried out in a standardized manner for a headrest model (2) intended to equip a range of vehicles.

3. Method according to claim 1, characterized in that the initial calibration is carried out specifically for each headrest (2) fitted to a given vehicle.

4. Headrest (2) programmable by a method according to any one of the preceding claims, said headrest comprising: • a fixed part (3) intended to be associated with the top of a backrest of said seat, • a movable part (la, lb) intended to receive the head of an occupant of said seat, said movable part being movable relative to said fixed part so as to be able to be adjusted according to the morphology of said occupant, • a device for actuating said movable part towards an adjustment position, said device comprising an electric motor (4), • at least one sound transmission device (5), • a programmable system for controlling said motor, said system being further programmable to generate a signal to said sound transmission device, so as to attenuate or eliminate the adjustment noise of said movable part.

5. Headrest according to the preceding claim, characterized in that a movable part is a main movable part (la) adjustable along a vertical axis (Z), the device for actuating said main movable part comprising, in addition to the motor (4): • a worm screw (6a) extending vertically, said screw being mounted in rotation on said main movable part, said screw being actuated in rotation by said motor also mounted on said main movable part, • a nut (7a) mounted on the fixed part (3), said screw cooperating with said nut so as to allow movement of said main movable part by rotating said screw.

6. Headrest according to the preceding claim, characterized in that it further comprises a secondary movable part (1b) adjustable along a longitudinal axis (X), said secondary movable part being slidably mounted on the main movable part (la), the device for actuating said secondary movable part comprising, in addition to the engine (4): • a worm screw (6b) extending longitudinally, said screw being mounted in rotation on said main moving part, said screw being actuated in rotation by said motor also mounted on said main moving part, • a nut (7b) mounted on said secondary moving part, said screw cooperating with said nut so as to allow movement of said secondary moving part by rotating said screw.