FR2930351A1 - Sliding door position measuring device for motor vehicle, has additional tube housing test pattern in passage for connecting test pattern with guiding element, where tube acts as waveguide for waves emitted by transceiver - Google Patents

Abstract

The device has a mirror type test pattern (5) integrated with a guiding element (3) of a sliding door, where the guiding element slides in a guiding rail (2). The test pattern is cooperated with a piezoelectric type wave transceiver e.g. diode (6), by interfering with propagation of waves for determining a position of the sliding door at a given instant. An additional tube (4) houses the test pattern in a passage for connecting the test pattern with the guiding element, where the tube acts as a waveguide for the waves emitted by the transceiver.

Description

  Measuring device by wave emission of the position of a sliding door of a motor vehicle

The present invention relates, in a general manner, to a device for measuring waves by the position of a sliding door of a motor vehicle. More particularly, but not exclusively, the present invention relates to a device for acoustically measuring the position of a sliding door of a motor vehicle, this device operating in absolute terms, that is to say not needing to be initialized with respect to at a starting position. In general, a sliding door of a motor vehicle can be moved in a first phase from a closed position applied against the body of the vehicle to a swaying position spaced from said body but substantially vis-à-vis the opening formed in the body, then in a second phase from the swaying position to a maximum open position, spaced from said body and recessed from the opening in the body in the longitudinal direction of the vehicle. This sliding can be done either manually or automatically, in this case, by a motor acting on the door, for example as a function of a signal emitted by an electronic management unit of the door from instructions such as a request opening or closing from the user as well as from the position of the door. For these sliding doors, especially when they are motorized, it is important to know the absolute position of the door to, for example, ensure that the execution of an opening or closing electric actuation control can be done. execute correctly even if this so-called door was manually operated before. To do this, it is known to use an incremental encoder coupled to the operating motor of the door. This sensor can be made optically by one or more sensors. The number of said sensors depends on the accuracy that is desired. This system can be enriched by a current measurement to determine the torque in the operating motor of the door. This current measurement can be performed in at least two ways: either by a current measurement shunt or by a Hall effect sensor based system. The incremental encoder sends a number of pulses per revolution of the motor shaft which allows to deduce the relative position of the door. One of the major faults of this type of encoder is: if it is no longer powered during a manual operation of the door, then it no longer fulfills its function of detection of stroke. In the latter case, only an abutment of the door by electric maneuver by driving the engine again allows to find and redefine the position and the stroke of the door. However, it happens that such a type of sensor is lost, this detection means being initialized with respect to a previous position, and can not be in a position to correctly determine the position of the door. In this case, only an abutment makes it possible to reset the sensor, which makes it an unreliable instrument for determining the position of the door.

US-A-6 343 437 discloses a motor vehicle sliding door with a position measuring device of this door comprising a non-contact sensor with the mechanism of the sliding door, this device being based on the counting of the teeth and the intervals between the teeth of a wheel whose rotation is representative of the displacement of the sliding mechanism of the door. This sensor thus determines the speed of rotation of the wheel and, according to it, the position of the door. In addition, a processing unit is provided for signal processing. This device however requires the addition to the sliding system of the door of an auxiliary mechanical device composed of this rotating wheel which has a certain disadvantageous size. The problem of the present invention is to provide a device for measuring the position of a sliding door of a motor vehicle that is able to precisely determine the position of this door, immediately after the distribution of electrical energy in the vehicle without obligation. to perform a race reset maneuver. For this purpose, the subject of the invention is a device for measuring the position of a sliding door of a motor vehicle, this door having at least one sliding guide element in a guide rail, characterized in that it comprises a A sight secured to one or the door guide element, this sight cooperating with a transmitter and a wave receiver by interfering with the propagation of these waves for determining the position of the door at a given instant. According to additional features of the present invention: the device comprises an additional tube housing this pattern by having a passage for the connection of this pattern with one or the guiding element of the door, this additional tube serving as a guide for waves for the waves emitted by the transmitter, the waves used may be either acoustic or ultrasonic waves, or light-wave beams of invisible, infrared, or visible light type such as LASER or LIDAR, or LED diodes , or electromagnetic type waves such as low and high frequencies or radio-frequency microwave frequencies, - the transmitter is a source of light energy, in particular in the form of a transmitting diode, a receiving diode measuring the amount of light reflected by the test pattern, this one being of the mirror type in order to reflect the light waves well. the transmitter and the wave receiver are merged and positioned at one end of this additional tube, the transmitter is of the piezoelectric type, the additional waveguide tube extends along the associated rail and has an additional tube portion bent at 180 °, at least the emitter being disposed at the free end of this additional tube part, the device is associated with a processing electronics of the emitted wave signals for the determination of the position of the door at a given instant, - the determination of the position of the door is done according to the time of the return and return of acoustic waves, of the audible or ultrasonic type, of light waves in the broad sense of the spectrum of light , or electromagnetic waves from the transceiver to the test pattern, - the determination of the position of the door is based on a measurement of the natural frequencies acoustic, audible or ultrasonic, the part of the tube comprri s between the transceiver and the test pattern, or the amount of light reflected by the test pattern for an optical system, or the amount of energy absorbed by the test pattern in an electromagnetic system.

The invention also relates to a sliding door of a motor vehicle, characterized in that it has such a device for measuring its position.

The invention finally relates to a motor vehicle, characterized in that it comprises such a sliding door.

The invention will now be described in more detail but in a nonlimiting manner with reference to the appended figures, in which: - Figure 1 is a schematic representation of a cross section of a guide rail of a sliding door having a position measuring device thereof according to the invention - Figure 2 is a schematic representation of a longitudinal section of a guide rail of a sliding door having a position measuring device thereof according to the invention, - Figure 3 is a schematic representation of a longitudinal section of a guide rail of a sliding door having a position measuring device thereof which can be used for a first and second mode of embodiment of the invention. FIG. 4 is a schematic representation of a cross section of a guide rail of a sliding door comprising a position measuring device thereof according to the invention corresponding to an optical type embodiment, this embodiment being the preferred embodiment of the present invention.

In what follows, the position measuring device of the sliding door according to the present invention uses acoustic waves for measurement. This should not be considered exclusive and the position measuring device is in no way limited to the use of such waves. The measuring devices, objects of the present invention, can use as waves ultrasound, or other types of acoustic waves such as light waves, radar, lidar or electromagnetic waves.

Figure 1 is a schematic representation of a cross section of a rail 2 for guiding a sliding door 1 having a position measuring device thereof according to the invention. When closed, such a door 1 first translates along the side wall of the vehicle and to the front thereof. At the end of the race, this door 1 performs a lateral translation inwards, following a circular arc, to return to its frame and lock. The mobility in translation of the door 1 is provided by guiding elements 3 of the door, integral with the latter and movable in guide rails 2, for example upper or lower rails of the frame extending inside the door. vehicle and / or the outer median rail.

The present invention consists in defining a particular design of at least one sliding rail 2 of the door 1 by adding to this rail 2 a device for measuring the position of the sliding door. Rail 2, which serves to guide at least one guide element 3 of the door 1, is associated with an additional tube 4 serving as a waveguide as will be seen later. This tube 4 is split by a slot 4 'thin over its entire length and extends in the same direction as the rail 2.

A sight 5 slides in the additional tube 4. This pattern 5 is rigidly connected to a guide member 3 of the movable door 1 in the rail 2, via a junction portion passing through the slot 4 'of the tube 4. This pattern 5 therefore follows the movements of the sliding door 1. In an electromagnetic system, this pattern 5 may be in the form of an antenna.

FIG. 2, which is a schematic representation of a longitudinal section of a guide rail 2 for a sliding door comprising a position measuring device thereof in accordance with the invention, shows an acoustic transceiver , in particular ultrasound, which is placed at the end of this additional tube 4. This transceiver 6 is fixed relative to the vehicle body and emits a wave for measuring, in one embodiment of the invention, via a signal processing, the round trip delay of the acoustic wave or ultrasonic. In this embodiment of the invention, the acoustic natural resonance modes of the tube 4 are measured, via signal processing, according to the movements of the pattern 5 in the tube that modifies the acoustic agreement of the tube.

The transceiver 6 may be of the piezoelectric, or electromagnetic, or optical type. An electrical signal is sent to him by the creation of electrical signals, not shown in the figures, in order to: - either to vibrate the piezoelectric sensor and thus to make it emit an acoustic or ultrasonic wave, - or to emit a light signal for an optical system, - either propagating an electromagnetic wave for a frequency system. This type of piezoelectric transceiver can be of the type already used in series, for example, in the case of obstacle detection sensors integrated into the bumpers. These transceivers are of the type employing a sensor and an acoustic actuator and can operate in both modes, i.e., in the transmit mode and the receive mode of a wave in the audible or ultrasonic domain. In the case of a piezoelectric type system the transmitter and the receiver can be confused. The transceiver means operates according to the following chronology: in transmission a part of the time (very short in term, for example for parking detection systems transmission lasts about 1 ms) duration, then enters a reception period , and transmits again and then returns to the receiving state, etc .... The emitter confused with the receiver is characteristic of a piezoelectric type sensor, that is to say in the case of a acoustic and / or ultrasonic means. In other cases, the transmitting room is distinct from the receiving room, except for the radar.

In the acoustic mode, the use of an additional tube 4 is made necessary because the main rail 2 is largely open on the outside and that the acoustic waves would not be guided sufficiently inside this rail 2. The attenuation of the acoustic waves could then be too important between their emission and their reception.

In addition, this rail 2, open on the outside, is subject to infiltration of dust or drops of water or particles that can influence the path of acoustic waves and their propagation time.

The present invention comprises three main embodiments for acoustic waves, knowing that the measuring device is not only limited to the use thereof. Figure 4 shows the preferred embodiment of the present invention. In this embodiment, the position measurement of the sliding door uses an optical type device with the diode 6 as light source, the pattern 5 is of the mirror type, and a diode 7 measures the amount of light energy. The diode 7 is placed at the bottom of a small waveguide so as not to be disturbed by the emission of the source 6. The operation may be of continuous type, the light source emitting energy continuously or of single pulse type or frequency modulated pulse. In anticipation with respect to the following descriptions, particularly with reference to FIG. 3, it is not necessary for operation with a light source to have an elbow and an over-length of as described in FIG. this embodiment the receiver diode may preferably be integrated in a small tube, a kind of light guide, in order not to be disturbed by the light-emitting source, as shown in FIG. over-length of and the associated elbow of Figure 3 is justified only in the case of an acoustic or ultrasonic system with the use of a piezoelectric means that plays both the role of issuer and also the role of receiver. After the emission due to the relaxation time constant of the ultrasonic sensor, the reflected waves can not be detected for approximately one millisecond (with sensor technologies similar to those currently used for obstacle detection for Parking assistance). This gives because of the speed of the acoustic waves in the air an over-length of about 30 cm. In the case of an electromagnetic radiation system (apart from the radar principle), this has a major disadvantage compared to the previous embodiments: A transmitter is associated with the workpiece 5, and the workpiece 6 constitutes the receiver (antenna measurement). The disadvantage of being the need for a wired connection, conveying the signal to be measured and amplified by the receiver, as well as the energy to be supplied by this measurement amplifier, such a structure becomes a little more complex in the embodiment. The emitted light source may be of continuous form or in the form of pulses or modulated by a frequency. The light spectrum can be in the visible or invisible domain. In the case of a system operating with microwave waves, the pattern becomes an antenna perceiving the amount of energy emitted by the transmitter 6. In this embodiment the over-length of and associated elbow no longer of reason to be. In another embodiment, the position measurement of the sliding door is based on the measurement of the travel times of the acoustic wave. In this embodiment, the duration of travel of the acoustic wave is measured between the transceiver 6 and the target 5 and return to this transceiver. It should also be noted that the position measuring device according to the present invention may comprise a dissociated transmitter and receiver. Let V be the speed of sound in the air of the additional tube 4 and the distance between the transceiver 6 and the target 5, as shown in FIG. 2, the duration t of the round trip is: t = 2d / V

It has been noted that one of the major drawbacks of current acoustic or ultrasonic transceivers is that when the receiver is used as a transmitter for a short period of time, due to the relaxation time of the material (piezo ) it can not distinguish in the reception phase the return wave which has been reflected by the test pattern 5. When the distance d between the test pattern and receiver is too small, the usual usual transceivers can not operate for this distance because the level of the return wave is mixed with the emission wave the part of the emitted wave. This can be compensated for by lengthening the tube. or by adding a reception sensor offset backward from the transmitter.

However, since, in the present case of absolute position measurement of a sliding door, for reasons of economy, cost and size, it is preferable to use only one transceiver. It is preferable to remedy this problem of short distance between the transceiver 6 and the target 5 in another way. The current series transceiver limits are of the order of 30 cm, which means that the Ate pulse duration and subsequent damping duration is approximately one millisecond. If this travel time is too small, the return wave returns while the transmit signal is not completely damped. The detection is then made very difficult.

Advantageously, it is proposed to extend the distance d between the transceiver 6 and the test pattern 5 and thus to lengthen the additional tube 4. Thus the return wave can return once the transmission phase is fully attenuated. It is then left at least between two packets of emissions enough time for the acoustic wave can make the longest round trip which corresponds to a door position, either fully open or completely closed. Advantageously, the length of the additional tube 4 is therefore lengthened. As it is difficult to lengthen this tube by changing its total length L, shown in Figure 3, for reasons of space, the embodiment of the invention, illustrated in Figure 3, shows a modification of the tube 4 additional with addition of a portion of additional tube 7 bent at 180 ° with respect to this additional tube 4 and thus folded thereon. This part 7 of additional tube has a length of and comprises at its non-bent end wave transceiver 6. The waves emitted traverse this part 7 of additional tube in one direction and then after the bend, the additional tube 4 in the other direction in order to reach the target 5 located in this tube according to the position of the guide element 3 in the rail 2. The waves are then reflected by the test pattern 5 and take the opposite path to the transceiver 6 where they are collected, thus allowing the determination of the position of the target 5 and, consequently, the element 3 of the sliding door in the rail 2. According to this embodiment, the addition of the length d according to FIG. 3 has the advantage of not increasing the total space requirement L of the additional tube 4 and therefore of the measuring device according to the invention.

The wave receiver, also emitter thereof for a short time, in this embodiment, is associated with a processing electronics, not shown in the figures, which, from the round trip time of the wave, allows to determine the position of the sliding door.

In the following, another embodiment of the device for measuring the position of a vehicle sliding door according to the present invention will be described. In this embodiment, the measuring device has essentially the same configuration so that Figures 2 and 3 can also be taken into account for a better understanding of this mode. Consequently, what has been previously explained in direct relation with these figures for the embodiment is also valid for this mode. On the other hand, this mode uses a measurement principle different from that of the previous one, this principle being based on the measurement of the acoustic natural frequencies of the additional tube and its additional bent part instead of being based on the measurement of the travel time of the an acoustic wave in this tube and its bent portion as for this embodiment. The first eigenfrequencies of a tube depend on the length of this tube and consist of frequencies with wavelengths sufficiently large compared to the dimensions of the tube. When this sufficiently low frequency range is reached, there is no transverse wave in the tube. The first acoustic natural frequencies of a tube are expressed as a function of the length of said tube. For a completely closed tube at both ends, the wavelengths of the acoustic eigenfrequencies are such that: d = nX / 2 where a, is the wavelength with X = c / f, where c is the velocity of the sound in the air of the tube, the length of the tube and f the wave frequency. For these acoustic modes pressure maxima are at the ends of the tube. For the first natural frequency, the lowest in frequency, there are only two maxima respectively at each end of the tube. In order to limit the frequency range, it is preferable to add, as in the previous embodiment, an additional length. When the length of the tube tends to zero, it corresponds to frequencies too high, higher than the appearance of transverse modes. The realization of this additional length is advantageously similar to that of the previous embodiment and shown in Figure 3, in the form of the additional tube portion bent. Thus, in this embodiment, a transceiver 6 is placed at the end of this additional tube portion 7. This transceiver 6 is still fixed relative to the body. The transmitter 6 sends a wave which is received by the receiver 6 after reflection on the pattern 5 which allows to measure, after signal processing, the natural frequencies of the tube.

According to this embodiment, the wave transmission and reception means may be of piezoelectric type, as already mentioned for the previous mode. The transmitter emits acoustic waves in the frequency range of the modes of said secondary tube. Depending on the length of the tube, a maximum of acoustic pressure appears at the frequency of this acoustic mode, and is detected at the receiver. A processing electronics processes the measurement signal of the natural frequency and returns the length information of the tube between the various elements of the measuring device.

For all measuring devices with acoustic, audible or ultrasonic wave emission, the speed of these in the air depends inter alia on the characteristics of the air, including its temperature. For more precision, temperature measurements by possible vehicle sensors can be taken into account in the processing electronics associated with the position measuring device of the sliding door, if necessary, via the management box. electronic door or other element present in the vehicle, for example the intelligent service housing or BSI.

The measuring device according to the present invention has the advantage of being able to provide a reliable measurement of the position of the sliding door at any time of the opening or closing thereof without having to be calibrated according to a measurement of departure.

The invention is in no way limited to the described and illustrated embodiments which have been given by way of example only.

Claims (12)

REVENDICATIONS1. Device for measuring the position of a sliding door (1) of a motor vehicle, this door (1) having at least one guide element (3) sliding in a guide rail (2), characterized in that it comprises a test pattern (5) secured to one or to the guiding element (3) of the door, this pattern (5) cooperating with a transmitter and a wave receiver (6) by interfering with the propagation of these waves for determining the position of the door (1) at a given moment. 2. Device according to claim 1, characterized in that it comprises an additional tube (4) housing this pattern (5) by presenting a passage (4 ') for the connection of this pattern (5) with one or the element guiding (3) of the door (1), this additional tube (4) serving as a waveguide for the waves emitted by the transmitter (6). 3. Device according to claim 2, characterized in that the waves used may be either acoustic or ultrasonic waves, or light beams of invisible type, infrared, or visible light such as LASER or LIDAR, or diodes LEDs, ie electromagnetic type waves such as low and high frequencies or radio-frequency microwave frequencies. 4. Device according to any one of the preceding claims, characterized in that the transmitter (6) is a source of light energy, in particular in the form of a transmitting diode, a receiving diode (7) measuring the amount of light reflected by the pattern (5), the latter being of the mirror type to reflect the light waves. 5. Device according to any one of claims 2 or 3, characterized in that the transmitter16 and the wave receiver (6) are merged and positioned at one end of the additional tube (4). 6. Device according to any one of claims 1 to 3, 5, characterized in that the emitter 5 (6) is of the piezoelectric type. 7. Device according to any one of claims 2,3 or 5, characterized in that the additional tube (4) extends along the associated rail (2) and has an additional tube portion (7) bent at 10 180 °, at least the transmitter (6) being disposed at the free end of this additional tube portion (7). 8. Device according to any one of the preceding claims, characterized in that it is associated with a processing electronics of the transmitted wave signals for determining the position of the door (1) at a given instant. 9. Device according to claim 6 and 8, characterized in that the determination of the position of the door (1) is as a function of the round-trip time of acoustic waves, of the audible or ultrasonic type, of light waves. in the broad sense of the light spectrum, or electromagnetic waves, from the transceiver (6) to the test pattern (5). 10. Device according to claim 6 and 8, characterized in that the determination of the position of the door (1) is based on a measurement of the acoustic natural frequencies, audible or ultrasonic, of the part of the tube between the transceiver (6) and the test pattern (5), or the amount of light reflected by the test pattern (5) for an optical system, or the amount of energy absorbed by the test pattern (5) in a system electromagnetic. 11. Sliding door (1) of a motor vehicle, characterized in that it has a device for measuring its position according to any one of the preceding claims. 17 12. Motor vehicle, characterized in that it comprises a sliding door (1) according to claim 11.5