Patent Application
20070176405
The present invention is relative to a motorized steering column module.
Such modules permit the position of the steering wheel to be adjusted as a function of the shape and the preferences of the driver by a movement [shift] in an axial direction and in a radial direction.
The movement in the axial direction allows the steering wheel to be brought closer to or further away from the driver. The radial movement is realized by tilting a part of the column along a pivoting axis perpendicular to the steering column. This allows the steering wheel to be raised or lowered.
Motorized steering column modules are known in the state of the art that comprise one or two motors for ensuring the movement in the two control directions. In the solutions with a single motor one or several electromagnetic clutches permit the driving mechanism to be coupled in accordance with the different control modes.
In the solution implementing two motors each one corresponds to one of the control directions.
These motors can be constituted by rotary or linear, electric, hydraulic or pneumatic actuators. They are controlled by an electronic controller that receives instructions from contactors that allow the driver to control the different movements. The controller also receives, or receives as an alternative, instructions coming from a central controller of the vehicle for recording reference positions.
It also receives movement instructions for moving the steering wheel into a position called “easy entry”, that frees to the maximum the access to the driver's seat at each entry into and exit out of the vehicle.
German patents DE19641152 or DE4217664 describe examples of modules known in the prior art.
The motors described are direct-current motors piloted by a control of the electromechanical relay type, static relay type or power electronic components controlled by switching. The motors are supplied with their nominal voltage for starting and during the control and are put in short-circuit for braking and stopping.
The problem posed is that transitory noises are produced during the starting or the stopping of the movement due to the resumption of plays, rapid deformations of the mechanical components of the control system of the steering column and of the elevated torque of the motor during starting. These noises are transmitted to the passenger compartment by the steering column by its very rigid definition and are therefore very difficult to filter.
In order to rectify this disadvantage of the modules of the state of the art the invention proposes an improved module characterized by an improved control law of the control motor or motors.
To this end, the invention concerns in its most general meaning a motorized steering column module with position control comprising means for moving [shifting] the steering wheel in an axial direction, bringing it closer or further away, and in a radial plane for regulating the position up and down with the aid of at least one electric motor control by an electronic means, characterized in that it comprises means for controlling a variation of the speed of this motor at least in the vicinity of the departure position and the arrival position.
This invention also has the goal of increasing the sensation of comfort when controlling the position of the steering wheel by a variation of the control speed. The sensation of robustness is also increased by a greater insensitivity to the variations of the supply voltage.
The controller is preferably programmed to control an acceleration of the movement during the motor startup and/or to control a deceleration of the movement during the approaching of the arrival position.
According to a variant the controller is programmed to ensure a compensation of the voltage variations of the motor supply.
The controller is preferably programmed to control a movement speed lower than the maximum speed upon approaching the position at the end of travel.
The motor is advantageously coupled to a sensor [pick-up] that delivers a signal that is a function of the real motor speed, which signal is transmitted to this controller.
According to a preferred variant the controller controls the reduction of the movement speed upon approaching the end of travel.
According to another variant the controller controls a mode of reduced-speed movement when it receives particular control instructions.
The controller advantageously generates motor control [command] signals in the form of constant tension scrambled at a variable cyclic ratio.
The parts activated by the motor preferably comprise at least one position reference sensor.
The invention will be better understood from a reading of the following description that refers to the attached drawings in which:
The invention is described below with reference made to a steering column control module comprising a first direct-current motor for adjusting the axial position of the steering wheel and comprising a second direct-current motor for adjusting the height of the steering wheel by tilting a section of the steering column relative to a transversal axis. The control mechanism will not be described in detail because it is known in the prior art and because the invention applies to every embodiment of such mechanisms. In particular, the invention is also applicable to mechanisms comprising a single motor and one or several clutches or linear, hydraulic or pneumatic motors. The motors can also be constituted by step-by-step [stepping?] motors controlled by a variable-frequency clock.
In the example described in a non-limiting manner each of the motors is piloted by a power electronic circuit controlled by a controller generating a modulated signal and with variable cyclic ratio (PWM (pulse width modulation) or MLI (modulation of impulse width) that permits the voltage to be controlled at the motor terminals from 0% to 100%.
At rest, the supply voltage of the motor is zero (range (1)). During the starting of the motor the supply is made with a minimum cyclic ratio (2) resulting in a non-zero minimal speed. The cyclic ratio then increases (3) progressively, e.g., in accordance with a linear law until the cyclic ratio achieves a maximal value corresponding, e.g., to the nominal or maximal speed. The speed is then maintained constant (4) until the stop command. This stop command can come from a position sensor, a manual command or an instruction calculated as a function of the prerecorded position sought. The speed then decreases (5), e.g., according to a linear law until reaching a slower control speed (6). Then, the motor supply is again reduced to a zero voltage (7).
Such a function presenting a succession of increasing, constant and decreasing slopes is not limiting. A function of the “Gaussian” type, e.g., can be envisioned.
It comprises in a customary manner a supply 9 and a controller 10 as well as power circuits 11, 12 respectively controlling motors 21, 22. Motors 21, 22 are respectively coupled to position/speed sensors 31, 32. The parts driven by motors 21, 22 are otherwise equipped with one or two position reference sensors 41, 51; 42, 52).
Controller 10 receives instructions from shaping circuitry 13 primarily realizing the adaptation of impedance (or of the leveling of voltage or current) of the signals coming from the switches “rise, descent”, and “return, exit”, also “facilitated exit” or “go into a given memorized position”. The controller also receives instructions coming from another controller of the vehicle or from other switches. These instructions are received in cabled [hard-wired] form or multiplexed via the intermediation of messages on a communication bus. In the case of instructions received in cabled form this module 14 is a shaping circuitry 13 primarily realizing the adaptation of impedance (or of the leveling of voltage or current) of signals permitting the recording of predefined positions, e.g., the preferred positions of different drivers of the vehicle. These positions are recorded in memory in a known manner and are called from a command not represented in this scheme. In the case of instructions received in multiplexed form via the intermediation of messages on a communication bus this module 14 is a controller/transceiver bus circuit. The totality of the messages is not defined here but it contains the commands “rise, descent” and “return, exit”, also “facilitated exit” or “go into a given memorized position” or “recording of predefined positions” and return messages about the state of the controller and the command in progress.
The controller also receives at its input the real voltage of supply battery 9 as well as position signals coming from sensors 31, 41, 51; 32, 42, 52).
The controller calculates control [command] signals of power circuits 11, 12 by determining the cyclic ratio in real time as a function of the state of the different inputs.
The regulation of speed maintains the speed instruction [order] of the column what ever the supply voltage furnished by the battery is: the cyclic ratio develops inversely proportionately to the supply voltage in order to compensate variations in voltage.
In a particular embodiment the control to a memorized position is made at 100% of cyclic ratio and every control by transitory actions on the control buttons is made at a reduced speed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0409517 | Sep 2004 | FR | national |
