LU93255B1 - Seat Sensor System - Google Patents

Abstract

A seat sensor adapted to be mounted within or on a seat of a vehicle. The seat sensor comprises a seat occupancy sensor for sensing a status related to a seat occupancy and for generating an output signal indicative of said status. The seat sensor comprises an autonomously powered transmitter device associated with the seat, said transmitter device being configured for wirelessly transmitting a data signal containing said output signal to a receiver module of a control unit within the vehicle. The autonomously powered transmitter device comprises an alternator (e.g. linear/vibration alternator) coupled to an electrical storage device (e.g. supercapacitor). A vehicle seat, a seat sensor system and a vehicle using the seat sensor(s) is also disclosed.

Description

Seat Sensor System

Technical field [0001] The present invention generally relates to a wireless seat detector e.g. for use in an automotive vehicle, to a seat, and to such a vehicle.

Background of the Invention [0002] In modern vehicles, seat occupancy sensors are widely used in order to detect whether a passenger seat is occupied or not. The information about the occupancy of the passenger seat may then be used in order to control the deployment of one or more airbags associated to the vehicle seat (for example, the deployment is inhibited if the vehicle seat is found to be non-occupied).

[0003] Today's automotive safety standards require automotive vehicles to be equipped with seat belt reminder systems for reminding a vehicle passenger to fasten the seat belt associated to the occupied vehicle seat. Such seat belt reminder (SBR) system comprise typically a seat occupancy sensor for detecting an occupancy of a vehicle seat and a seat belt sensor, e.g. a buckle switch sensor, for detecting whether a seat belt is fastened or not. Increasingly, standards require that not only front seats, but also rear seats, be equipped with such seat occupancy sensors and seat belt reminder systems.

[0004] The seat occupancy sensors used in airbag control systems or seat belt reminder systems usually comprise pressure sensing devices integrated in the respective passenger seat for detecting a pressure induced by the presence of a passenger into the seat, e.g. as disclosed in DE-A-42 37 072. The seat belt fastening detectors of seat belt reminder systems typically comprise mechanical or magnetic buckle switches for detecting, whether a latch of the seat belt is inserted into the seat belt buckle, e.g. as disclosed in US Patent US-A-5,871,063.

[0005] One drawback of these known seat sensors lies in the fact that the seat occupancy sensor and/or the seat belt fastening detector have to be physically connected to the control unit by means of connection wires in order to be functional. This need for physically connecting the sensing device to the control unit however causes problems especially in modern cars equipped with a flexible seating system with removable and/or displaceable back seats. One solution is proposed in US 2007/241545 A1, which discloses that each (rear) sensor comprises a self-powered transmitter associated with a seat for transmitting a data signal to a control unit comprising a receiver module for receiving the data signal. The autonomously powered transmitter comprises a transmitter module, a piezo generator for converting a mechanical energy into electrical energy and an electronic converter unit for generating a transmitter module power supply. However, a problem with such piezo generators is that, as they are also used as occupancy detectors, they can only be mounted at particular positions, i.e. at or near seat surfaces and/or where there is a substantial amount of soft material between the piezo generator and the vehicle chassis, potentially reducing the amount of mechanical energy received. In particular, conventional piezo generators may not be suitable for rigid mounting to (the base of) a car seat or on its exterior, i.e. so effectively rigidly mechanically attached to the vehicle chassis.

Object of the invention [0006] A problem addressed by the present invention is how to provide at least an alternative and improved seat sensor, which is suitable for association with removable vehicle seats.

General Description of the Invention [0007] In order to overcome the abovementioned problems, the present invention provides a seat sensor adapted to be mounted within or on a seat of a vehicle, the seat sensor comprising: a seat occupancy sensor for sensing a status related to a seat occupancy and for generating an output signal indicative of said status; and an autonomously powered transmitter device associated with the seat. The transmitter device is configured for wirelessly transmitting a data signal containing said output signal to a receiver module of a control unit within the vehicle. According to the invention, the autonomously powered transmitter device comprises an alternator coupled to an electrical storage device.

[0008] The seat sensor system of the present invention is configured so as to enable remote communication between the seat sensor associated to the seat and the control unit for the seat sensor. The seat sensor accordingly transmits the data signal containing information regarding the seat occupancy related status wirelessly to the control unit. It follows that the seat sensor does not need to be connected to the control unit by means of connection lines. No wiring of the seat sensor being necessary, the seat sensor system does not negatively affect the advantages of the flexible seating systems of modern vehicles with removable and/or displaceable back seats.

[0009] According to the present invention, the transmission of the data signal is achieved by means of a self-powered transmitter, i.e. an autonomously powered transmitter device. Such autonomously powered transmitter devices include a device for converting a mechanical energy into an electrical energy. Accordingly, the autonomously powered transmitter device relies neither on an external electric power supply (connected by cabling) nor on internal battery power. The autonomously powered transmitter device is accordingly suitable for autonomous operation which eliminates the need for cabling or occasional battery replacement. [0010] Preferably, the seat comprises a rear bench of a vehicle.

[0011] Preferably, the alternator comprises a linear alternator. Preferably, the alternator is adapted to be mounted within the seat such that, in use, the axis of the alternator is vertical or at an acute angle to the vertical, or 45 degrees or less to the vertical. Vibrations caused by the vehicle movement act on the armature of the alternator, so that the alternator generates the required power for the electronic unit.

[0012] The seat sensor preferably comprises a rigid housing, the housing being adapted to be rigidly attached to the seat. Preferably, the housing has an axis of elongation. Preferably, the housing is adapted to be rigidly attached to the seat at a first end thereof.

[0013] Preferably, the alternator comprises (i) an elongate armature, the armature having a first end thereof attached to a first end of the housing via a first resilient element, and/or having a second end thereof attached to a second end of the housing via a second resilient element, and/or (ii) a coil winding, coaxial with the axis of elongation of the housing and fixed thereto, whereby the armature is arranged, in use, to translate through the interior of the coil winding, and/or (iii) an elongate armature having north and south poles disposed at respective ends thereof, and/or (iv) a housing made of rigid non-conducting material.

[0014] The seat sensor preferably further comprises an electronic converter unit for generating a transmitter module power supply from electrical energy induced in the alternator. Preferably, the converter unit comprises a half wave rectifier or a full wave rectifier..

[001 o= Preferably, the electrical storage device comprises a supercapucifor, [00181 Preferably, the transmitter device further comprises processing means for encoding said output signai With a dig-fal ID of said seal sensor into said data signal.

[00T?I According to another aspect of the invention, there is provided a vehicle seat comprising.· a seat body comprising a seat surface, and a seal sensor as disclosed above rigidly mounted within or on the seat body, and preferably wherein said seal occupancy sensor comprises pressure sensitive switching device comprising a plurality of Individual pressure sensors or switches arranged at different locations with respect to a seat surface.

[0018] According to another aspect of the invention, there is provided a .soar, sensor system for a vehicle, the seat sensor system comprising; at least one seat sensor as disclosed above, or a seat as described above, the at least one seat sensor being for sensing a status related to a seat occupancy and for generating an output signal indicative of said status; and a control unit for communicating with said at least one seat sensor, wherein said autonomously powered transmitter device is configured for transmitting the data signal containing said outpi.it signal and the control unit comprises an receiver modulo tor receiving said data signai from said autonomously powered transmitter device.

[0010] The control unit receives the data signal transmitted from the seal sensor and may further process this signal in order to e.g, generate either a warning signal (In case of a seat belt reminder system) or an airbag control signal (if the seal sensor is used for controlling the deployment of the airbagfs) associated with the seat). As the data signal from the seat sensor is remotely received, the control unit does not need to be Installed into the vehicle seat but may be arranged at any suitable stationary location Inside the vehicle. The control unit Is accordingly not Integrated Into a (possibly) removable or displaceable seat so that power supply via cabling or wired connection to further components of the vehicle's electronic system is no issue.

[0020] The present seat sensor system thus enables autonomous seat occupancy detection in the seat, which in addition does not require regular maintenance. Accordingly the present seat sensor system is perfectly suited for the operation in removable vehicle seats.

[0021] It will be noted that the control unit should preferably be mounted into the vehicle in such a way that a receiving antenna of the receiver module is centrally located into the vehicle compartment. In this case, the control unit may receive data signals transmitted both from seat sensors arranged in front vehicle seats and in rear seats. In this embodiment, the seat sensor system may comprise a plurality of seat sensors associated with different seats of a vehicle, and said control unit may be configured for communication with each of said plurality of seat sensors. A single common control unit reduces the complexity of the sensor system and consequently the overall costs of the system.

[0022] According to another aspect of the invention, there is provided a vehicle comprising a seat sensor, a seat or a seat sensor system as disclosed hereinabove.

[0023] The autonomously powered transmitter device preferably comprises a transmitter module, the alternator for converting a mechanical energy into electrical energy and an electronic converter unit for generating a transmitter module power supply from said electrical energy.

[0024] An electronic converter unit may be used to convert the high voltage pulses of the alternator into a suitable DC current for supplying the transmitter module. In a very simple embodiment, the electronic converter unit may comprise a simple diode as rectifier, or a full wave rectifier, and/or voltage limiter.

[0025] The transmitter module may be a low power RF transmitter. Radio waves pass freely through people and non-metallic parts such that safe transmission to the control unit is ensured. In a preferred embodiment, said autonomously powered transmitter device further comprises processing means for encoding said output signal with a digital ID of said seat sensor into said data signal. In a multi-sensor environment, i.e. if the seat sensor system comprises a plurality of seat sensors, each individual seat sensor, from which a specific signal emanates, is infallibly identifiable by the control unit so that the appropriate measures may be taken with respect to the correct seat.

[0026] In an embodiment, in which the autonomously powered transmitter device is only used for its power generating and signal transmitting properties, the seat sensor further comprises a seat occupancy detector for sensing an occupancy of said seat, said pressure sensor being connected to said autonomously powered transmitter device and/or a seat belt fastening detector for determining a seat belt usage condition related to said seat, said seat belt fastening detector being connected to said autonomously powered transmitter device. In these embodiments, the individual sensing functions are performed by dedicated specialized sensing elements. The occupancy sensor may e.g. comprise a pressure sensitive switching device comprising a plurality of individual pressure sensors or switches arranged at different locations with respect to a seat surface. These pressure sensitive switching devices have proven to be very reliable and well adapted to the detection of seat occupancy.

[0027] It will further be appreciated, that the seat belt fastening detector preferably comprises a seat belt buckle switch sensor. This seat belt buckle switch sensor is integrated into the seat belt buckle for detecting, whether the latch of the seat belt is inserted into the seat belt buckle. The seat belt buckle itself is typically mounted on the seat and not on the vehicle floor and accordingly the seat belt buckle is removable together with the seat (as is as the seat occupancy sensor). The buckle switch is connected to the autonomously powered transmitter device, so that the fastening status of the seat belt may be included into the data signal to be transmitted to the control unit.

[0028] Advantages of the invention, at least in embodiments, include the following: no harness connection between the dashboard and rear bench (i.e. little vehicle body structure change); no battery needed for the whole system; green technology usage; no maintenance needed; improved convenience in implementation; and high reliability.

Brief Description of the Drawings [0029] Further details and advantages of the present invention will be apparent from the following detailed description of non-limiting embodiments with reference to the attached drawing, wherein:

Fig.1 shows part of a vehicle compartment with a first embodiment of a seat sensor system associated with a vehicle seat;

Fig.2 is a schematic block diagram of the seat sensor system of Fig. 1 ;

Fig.3 shows a block diagram of an embodiment of the seat sensor used in the system of Fig. 2; and

Fig. 4 is a schematic cross-sectional view of an alternator used in the seat sensor of Fig. 3.

Description of Preferred Embodiments [0030] In the following, like numerals will be used to indicate like elements.

[0031] Fig. 1 schematically illustrates an interior compartment 10 of a vehicle with a passenger 12 sitting on a rear seat (or rear bench) 14. The vehicle seat 14 is equipped with a seat sensor 16 which remotely communicates with a receiver module 18 of control unit 20. Control unit 20 is mounted in a suitable location in the vehicle compartment, e.g. on the vehicle floor or onto the vehicle roof, and more preferable at/under the dashboard (not shown). Control unit 20 is preferably mounted into the vehicle in such a way that a receiving antenna 22 of the receiver module 20 is substantially centrally located into the vehicle compartment 10. In this case, the control unit 20 may receive data signals transmitted both from seat sensors arranged in front vehicle seats (not shown) and in rear seats 14.

[0032] In the embodiment shown, the seat sensor 16 comprises a seat occupancy sensor 24 arranged in the seat cushion of seat 14. The seat occupancy sensor 24 typically includes a pressure sensitive switching mat having a plurality of individual pressure sensors distributed over the seating area of the seat 14; and it will be appreciated that a separate seat occupancy sensor 24 may be provided for each of the multiple (typically three) seating positions on the rear bench 14 of a vehicle; however, not all are illustrated in Fig. 1.

[0033] The seat occupancy sensor 24 is connected to a transmitter module 26 (also referred to herein as “Transmit ECU” or “Trans ECU”) - preferably an RF transmitter, which is able to transmit an occupancy related output signal from the seat occupancy sensor 24 to the control unit 20. Transmitter module 26 is, for example, arranged in the base of the seat 14 and is part of a self-powered transmitter, which further comprises an alternator 28 associated with the transmitter module 26.

[0034] The alternator 28 is integrated into the seat cushion of the vehicle seat, or built into the supports therefor, so as to be exposed to vibrations as the car moves. The alternator 28 then converts mechanical energy (vibrations due to movement of the car) into electrical energy, which is converted into a suitable DC supply voltage for transmitter module 26 by means of a power converter 30 (see Figs 2-4).

[0035] In the embodiment shown, the seat sensor 16 comprises a buckle switch sensor 32, which is integrated into the seat belt buckle for detecting, whether the latch of the seat belt 34 is inserted into the seat belt buckle. Like the seat occupancy sensor 28, seat belt buckle switch 32 is also connected to transmitter module 26. It should be noted, that transmitter module 26 may transmit the individual output signals of the seat occupancy sensor 26 and the buckle switch sensor 32 separately to the receiving module 22. In a preferred embodiment, transmitter module comprises however a processing unit 36, which is able to combine the individual output signals into a combined data signal to be transmitted. Furthermore, the processor means is preferably configured for encoding the combined output signal with a digital ID of said seat sensor into said data signal. In a multi-sensor environment, i.e. if the seat sensor system comprises a plurality of seat sensors, each individual seat sensor is then identifiable by the control unit so that the appropriate measures may be taken with respect to the correct seat.

[0036] Fig.2 is a schematic block diagram of the seat sensor system 15 of Fig. 1, The seat sensor system 15 comprises the control unit 20 (also referred to as "Receive ECU” herein), which is for example mounted on/under the dashboard. The control unit 20 is powered by the vehicle battery 36 and includes a first microcontroller unit 38 coupled to the wireless receiver 18 and to a CAN transceiver 42, i.e. an integrated circuit (IC) able to generate or receive signals for communicating over the Controller Area Network which is typically used in automotive vehicles, The CAN transceiver 42 in torn supplies signals to the safety belt reminder module 44. It should be noted that instead of the CAN transceiver, one could es well use a UN transceiver for communicating over the Local interconnect Network commonly used In automotive vehicles.

[8037] As seen or? the right hand Side of Fig, 2, on the roar bench there are throe seating positions, and each has a respective pair of sensors - one each of occupancy detection (SBR) sensors 24a, 24b, 24c and of buckle sensors 32a, 32b or 32c. 100381 In use, the first microcontroller unit 38 receives signals (wirelessly, as indicated at 46) from transmitter module or “Trans ECU” 28, These signals may include an Indication that a particular seating position on the roar bench is occupied, and If the passenger is not (yet) wearing a seatbelt, a further signal 0 e. from buckle sensor 32a, 32b or 32c Indicating that the seatbelt is not in use), in response, first microcontroller unit 38 may cause an audible/vislble alert or warning to be Issued to one or all passengers via safety belt reminder module 44, [0038] The signal are transmitted by transmitter module or ''Trans ECU” 28, which includes second mlcrocoritroiler unit SO coupled to wireless transmitter 32, antenna 54, and linear alternator (also referred to herein as “shaking alternator or “vibration alternator”} 28 which supplies power to supercapacitor 58 via a conversion unit, here simply a diode rectifier 53, as will he discussed in further detail hereinafter, (0848} Fig, 3 shows a block diagram of an embodiment of the seat sensor 18 used in the seat sensor system 15 of Fig, 2, Signals from occupancy sensors 24a, 24b and/or 24c are fed to second microcontroller unit 50 as and when generated. This is also the case with buckle sensor 32a, 32b and/or 32c (not shown in F?g. 3), Under the control of second microcontroller unit 88. wireless transmitter 32 wireless trarssmlts signals indicative of seat occupancy and/or buckle (seatbelt) usage via antenna 64,. (0841] In order to be supplied with power, transmitter module or “Trans ECU” .28 includes linear/shaklng alternator 28, which converts vibrational energy due to movement of the vehicle chassis (vibration) Info electrical energy. The latter Is fed to an electrical storage device, in this embodiment a supercapacitor 56, following conversion (rectification) at conversion unit, in this case diode rectifier 58.

[0042] Fig. 4 is a schematic cross-sectional view of an alternator (linear or “shaking alternator”) 28 used in the seat sensor 16 of Fig. 3. The alternator 28 includes an elongate housing 60 having an axis 62, the housing 60 being formed, for example, of a rigid plastics material. The walls of the housing 60 may be electrically shielded, where appropriate. A coaxially arranged elongate armature 64 is formed by a permanent magnet having a south pole 66 and a north pole 68. A first end 70 of the armature 64 is fixed via first coil spring 72 to a first internal endwall 74 of the housing 60. A second end 76 of the armature 64 is fixed via second coil spring 78 to a second internal endwall 80 of the housing 60. Surrounding the armature 64 is a coil winding 82, e.g. formed of copper wire. The coil winding 82 is fixedly mounted in relation to the housing 60 and has ends 84 and 86.

[0043] In use, vibrations of the vehicle cause translations of the armature 64 relative to the coil winding 82, thereby generating alternating current (AC) in the coil winding 82 which is fed out at ends 84 and 86. The latter are coupled to a conversion unit, in this case a full wave rectifier, so as to supply direct current (DC) to supercapacitor 56. The latter may have a large capacity. E.g. of the order 4F. Such a device can store electricity while shaking/vibration is very strong but the transmitter isn’t required to send the data. It can then supply the transmitter when a high power is needed to send the data. In practice, for most of the time, the transmitter will go to sleep and only during a very short time will send data to the receiver. The other components such as MCU 50 and SBRs 24 and buckle switches 32 will usually go to sleep and typically operate only for a very short time. The average current consumption can be as low as 0.6uA.

List of Reference Symbols 10 compartment 50 second microcontroller unit 12 passenger 52 wireless transmitter 14 vehicle seat 54 antenna 16 seat sensor 56 super capacitor 18 receiver module 58 diode rectifier 20 control unit 60 housing 22 antenna 62 axis 24, 24a, 24b, 24c seat occupancy 64 armature sensor 66 south pole 26 transmitter module 68 north pole 28 piezo-generator 70 first end 30 power converter 72 first coil spring 32, 32a, 32b, 32c buckle switch 74 first endwall sensor . . 76 second end 34 seat belt , . , 78 second coil spring 36 vehicle battery a i 80 second endwall 38 first microcontroller unit , 82 coil winding 42 CAN transceiver ,, ., ,, 84,86 ends of coil winding 44 Safety belt reminder module 88 full wave rectifier

Claims (15)

1. Seating device adapted to be mounted within or on a seat of a vehicle, wherein the vehicle sensor comprises a sensor for detecting a status, detecting seat occupancy, and generating an output signal indicative of that status and an autonomous lift Broadcasting assigned to the sltz let. wherein the transmitter transmitter dater is adapted, at the Dafansignai, which includes the output signal, to promptly transmit to an emitter module of a control console within the vehicle, characterized in that the autonomously sendered transmitter device generates an alternating current generator. which is gekdppeit to an eiekfrische Spelchervorriohfung exhibits 2. Sltzsensor need claim 1. wherein the Sltz includes a Rbekbenk of a vehicle. 3. Sitzsenscr according to claim 1 or 2, wherein the Wechselstremgenerator comprises an iinearen Wechselstremgenerator. 4. Sltzsensor according to claim 1, 2 or 3, wherein the Weehseistromgenerator is adapted to be so warmed within the seat, which in Gebrauoh the Acbse the Wechselstromgenerals verti cal or io an acute angle to Vertikasen, or 45 degrees or less Verlskaien ilegt 5. Sitzsenscr according to one of the votsiehenden claims, comprising a rigid Geh'use, wherein the housing is adapted to beerstra brated to the Sltz. 6. A seat sensor according to claim 5, wherein the housing has an expansion axis. 7. A seat sensor according to claim 6 or any claim dependent thereon, wherein the housing is adapted to be rigidly attached to the seat at a first end thereof. 8. A seat sensor according to claim 6 or any claim dependent thereon, wherein the alternator comprises: an extended armature, wherein a first end of the armature is attached via a first resilient member to a first end of the housing, and / or wherein a second end the armature is attached to a second end of the housing via a second resilient member, and / or a helical coil which is coaxial with and fixed to the extension axis of the housing, the armature, in use, being arranged to pass through the interior the screw winding is displaced, and / or an elongated anchor with a north and a south pole, which are arranged at respective ends thereof, and / or a housing made of a rigid, non-conductive material. 9. A seat sensor system according to any one of the preceding claims, further comprising an electronic transducer unit for generating a transmitter module power supply of electrical energy induced in the alternator. 10. A seat sensor according to claim 6 or according to a dependent therefrom claim, wherein the transducer unit comprises a half-wave rectifier or a full-wave rectifier. 11. A seat sensor system according to any one of the preceding claims, wherein the electrical storage device comprises a supercapacitor. A seat sensor according to any one of the preceding claims, wherein the transmitter device further comprises processing means for encoding the output signal with a digital ID of the seat sensor into the data signal. 13. A vehicle seat, comprising: a seat body having a Sitzfiäche, and a seat sensor according to one of the preceding claims, which is rigidly mounted within or on the seat body, and preferably wherein the seat occupancy sensor comprises a membrane switching device having a plurality of individual pressure sensors or switches which are arranged at different positions with respect to a seat surface. 14. A seat sensor system for a vehicle, the seat sensor system comprising: at least one seat sensor according to one of claims 1 to 12, or a seat according to claim 13, wherein the at least one seat sensor for detecting a seat occupancy status and generating an output signal indicates the status, serves; and a controller for communicating with the at least one seat sensor, wherein the autonomous transmitter device is configured to transmit the data signal containing the output signal, and the controller comprises a receiver module for receiving the data signal from the autonomously operated transmitter device. 15. A vehicle comprising a seat sensor according to any one of claims 1 to 12, or a seat according to claim 13.