Electronic MonitorThis invention relates to an electronic monitor suitable for example for use on a vehicle.
It is well known to provide aircraft with a flight recorder or 'black box' which is connected electrically to various sensors within the aircraft, and which maintains a record on a magnetic medium of information about those sensed parameters during a short period which may be just a few minutes. The use of tachographs is also widespread in commercial vehicles, which are connected to vehicle instruments and which provide a record, on paper, of the speed at which the vehicle has travelled throughout a time period of a few hours. The use of electronic memories is also well known, and such memories may be incorporated into a smart card used to record for example financial transactions.
According to the present invention there is provided an electronic monitor comprising at least one sensor for sensing a parameter of the environment of the monitor, an electronic memory for recording data relating to the sensed parameters over a prolonged period, means to control the recording of the data, and a power supply, the sensor or sensors, the memory, the control means and the power supply being integral with each other so as to form a self-contained monitor.
The prolonged period is preferably many days, for example a period of months, or even a year or longer.
Such a monitor can be installed at a desired location, and the recorded data read out after a prolonged period such as every two months. The monitor might be removed when the data is to be read out, or the readout might be performed in situ.
The power supply desirably includes a battery to provide the requisite electrical power for operation of the monitor, and desirably also includes means such as a solar cell or a moving body electrical generator to ensure the battery remains charged.
The monitor may be for use on a vehicle, for example a railway truck or carriage (or other item of rolling stock). It might for example be installed on a bogie of a rolling stock car. The sensor or sensors will clearly be dependent upon the nature of the parameters about which data are required, and might for example include motion detectors, temperature sensors, pressure sensors, accelerometers, and/or rotation detectors. The monitor may in some cases be also connected to a separate sensor remote from the monitor, for example to sense the temperature within a component of a vehicle such as a gearbox or bearing. The monitor desirably includes an integral real-time clock or timer.
The recorded data may comprise instantaneous values of a parameter for example at hourly intervals, or average values taken over successive periods for example over two-hour periods, or peak values attained during such successive periods. In the case of some parameters (such as distance travelled) the cumulative value of the parameter may be what is recorded. And in some cases data may be recorded only if a parameter exceeds a certain threshold, for example to record merely the number of occasions for which the acceleration exceeds a threshold; or the date and time at which the acceleration exceeds a threshold; or to record the cumulative time for which a parameter exceeds a threshold, for example the cumulative time during which a vehicle is moving, or during which ambient temperature is below freezing.
If such a monitor is used on a railway rolling stock car, which may be for passenger or freight, it can enable the loads imposed on the railway track by the car to be monitored, and hence the degree of damage to the track objectively assessed. It also can enable the use of the car to be monitored, so that maintenance of the car can be carried out on the basis of the actual wear due to distance travelled and payload characteristics.
The invention will now be further and more particularly described, by way of example only, and with reference to the accompanying drawings in which:Figure 1 shows a diagrammatic cross-sectional viewof part of a railway freight truck, including amonitor unit; andFigure 2 shows a functional diagram of the monitorunit of Figure 1.
Referring to Figure 1, a railway freight truck 10 consists of a truck body 12 supported by springs 14 above a bogie frame 16, the bogie frame 16 defining bearings for axles 18 connecting pairs of wheels 20 (only one axle 18 is shown). It should be appreciated that the Figure represents these components only diagrammatically. Also attached to the bogie frame 16 is a self-contained monitor unit 22. In this example the unit 22 is near a position on the axle 18 to which a small permanent magnet 24 is fixed; and a rod 26 fixed to the body 12 projects downwardly and carries a permanent magnet 28 at its lower end adjacent to one side of the unit 22.
Referring now to Figure 2, the monitor unit 22 is shown as a block diagram. It is an essentially solid state, self-contained device, primarily constructed by use of microstructural device technology out of silicon.
It incorporates a low power microprocessor 30 connected to a random access memory 32. The microprocessor 30 is also connected to a number of sensors 34, 35, 36, 37 (described below), to a power supply 40 (described below), to a real-time clock or timer unit 42, and to an input/output unit 44 whereby the data recorded in the memory 32 can be read out. The power supply 40 incorporates a battery 46, a motion-to-power transducer 47 and a control circuit 48 to control the charging current supplied to the battery 46. The microprocessor 30 processes the signals from the sensors 34-37 and manages the recording of data by the memory 32.
The sensor 34 is a semiconductor thermocouple providing signals representing the ambient temperature.
The sensor 35 is a Hall effect sensor which is adjacent the magnet 24 on the axle 18, so it provides a pulse for every rotation of the axle 18. The sensor 36 is adjacent the magnet 28 connected to the truck body 12 and gives a signal corresponding to the position of the magnet 28 relative to the unit 22; with a knowledge of the properties of the springs 14 this enables the weight of the load in the truck 12 to be calculated. The sensor 37 is a 3-D accelerometer, consisting of three microstructural cantilever accelerometers arranged to provide signals respectively representing the acceleration in three orthogonal directions.
The signals from the pulse counter 35 enable the microprocessor 30 to determine whether the truck 10 is stationary or moving, and if moving to determine how far it travels. The memory 32 records the cumulative running time, the cumulative stationary time, and the cumulative distance travelled.
The signals from the displacement sensor 36 enable the mass of the load in the truck 10 to be determined.
The memory 32 records the mass whenever it differs from the previously-recorded mass (indicating the truck 10 has been loaded or unloaded), and the date and time at which the mass is recorded is also stored in the memory.
The signals from the 3D-accelerometer 37, combined with the current mass of the truck 10, enable the forces on the bogie to be determined in three orthogonal directions. The forces observed while the truck 10 is moving enable the acceleration and braking forces on the truck 10 to be determined, and enable the corresponding loads on the track to be determined too. The peak values of loads which exceed a threshold are recorded, along with the date and time at which it occurred. In addition the cumulative track load can be recorded.
The signals from the thermocouple 34 enable a record to be made of the average temperature, and the maximum and minimum temperatures, experienced each day.
Periodically, for example every month, the recorded data is read, and the memory reset. This may be done by removing the unit 22, and connecting the input/output unit 44 to a reader (not shown) connected to a computer, if the unit 44 has electrical output contacts.
Alternatively the output of data might involve for example magnetic coupling to a reader, and the unit 22 might be read in situ. Yet again the input/output unit 44 might transmit the recorded data by radio to a suitable transceiver when triggered to do so, and this would enable the data to be read remotely, for example while the truck 10 is passing a station. The data thus obtained might be downloaded to a central database for maintenance scheduling, usage monitoring and scheduling, and costing. The memory 32 might be left with historical information such as the date of the last maintenance, an identity code for the individual truck 10, and the name of the owner or lease holder of the truck 10.
It will be appreciated that a monitor unit may differ from that described above while remaining within the scope of the invention. In particular the recorded data relating to the measured parameters might differ from that described above. Indeed different sensors might be used, and different parameters might be sensed.
For example a unit might include heat flux sensors, gyroscopes, torque and force sensors, microphones, Halleffect sensors, gas sensors, chemical sensors and/or optical and infra-red sensors. Other applications for monitor units might be for example to monitor the operation of doors on railway carriages, to monitor the flexing of aircraft wings, to monitor the speed and usage of motor vehicles on roads, or to monitor industrial plant in remote or inaccessible locations. It will also be appreciated that other types of data read-out may be used, for example using optical or infra-red radiation, or ultrasonic transducers.