GB2386422A

GB2386422A - Wheel rotation monitor

Info

Publication number: GB2386422A
Application number: GB0205834A
Authority: GB
Inventors: Graham Edward Curtis; Clive Hannaford; Brian George Davenport
Original assignee: AEA Technology PLC
Current assignee: Ricardo AEA Ltd
Priority date: 2002-03-13
Filing date: 2002-03-13
Publication date: 2003-09-17
Anticipated expiration: 2022-03-13
Also published as: GB0205834D0; GB2386422B

Abstract

A wheel rotation monitor 36 includes a housing 40 for mounting on the wheel 29 of a vehicle. The housing 40 encloses an electrical generator, a data recorder for storing data representing the number of rotations of the wheel, and a transmitter for transmitting data to an external station. The monitor unit 36 is attached to the end of an axle 29 and the housing 40 rotates with the axle. The housing 40 may include a bearing 50 supporting a freely rotatable rotor 54 placed within the housing, the rotor 54 being weighted so it remains stationary during axle rotation. Interaction between windings in the rotor 54 and magnetic poles in the housing 40 can both provide signals indicating rotation and also generate electricity. Signal pulses are generated, stored and transmitted. Transmission may occur on receipt of external signals or when the vehicle stops. The housing may include additional sensors (e.g. temperature). The monitor may be used for railway vehicles.

Description

1- 2386422

Wheel Rotation Monitor This invention relates to an electronic monitor for monitoring rotation of a wheel, particularly but not 5 exclusively a wheel of a railway vehicle.

For monitoring vehicle usage, for example for planning vehicle maintenance, it is desirable to know how far a wheel has travelled. A vehicle with a driver may 10 have a mileometer in the cab that indicates how far that vehicle has travelled, but there is a particular problem with railway vehicles, as individual trucks or carriages may be incorporated in several different trains in the course of a year so that monitoring how far each vehicle 15 has travelled is rendered more complex. Although mechanical rotation monitors are known, these cannot be read automatically.

Accordingly the present invention provides a wheel 20 rotation monitor including a housing for mounting on a wheel of a vehicle, the housing enclosing means for generating electricity, means for recording data representing the total number of rotations of the housing, and a transmitter for transmitting such data to 25 a sensor external to the monitor.

Preferably the housing incorporates a bearing, and the monitor comprises a freely rotatable monitoring element supported on the bearing, the monitoring element 30 being asymmetrical in its weight distribution so that rotation of the housing does not cause rotation of the monitoring element, the monitoring element incorporating means for detecting rotation of the housing relative to the element.

The electricity generating means may comprise one or

- 2 more magnet poles within the housing, and one or more coils in the monitoring element. The rotation detecting means may be at least part of the electricity generating means. Thus the rotations may be monitored by monitoring 5 the electricity generated in at least one coil.

Preferably the poles and coils are arranged so that the relative rotation generates a sequence of electrical pulses, and means are provided for counting those pulses.

Preferably means are also provided to restrict the 10 magnitude of the current in the coils, and so to restrict the electromagnetic torque on the monitoring element.

The transmitter may be arranged to transmit the data as a radio signal, and may be arranged to transmit this 15 data whenever the vehicle stops. Alternatively the monitor may incorporate a signal receiver, and be arranged to transmit the data in response to receipt of a signal by the signal receiver. Preferably the data that is transmitted also includes data identifying the 20 vehicle.

The monitoring element may also comprise sensors for monitoring other parameters, this additional data also being transmitted. For example there might be a 25 temperature monitor, exceptionally high temperature values indicating excessive friction in the bearing for the wheel set.

The invention will now be further and more 30 particularly described, by way of example only, and with reference to the accompanying drawings in which: Figure 1 shows a side view of part of a railway vehicle including a wheel rotation monitor of the 35 invention;

- 3 Figure 2 shows a sectional view on the line 2-2 of figure 1 showing the wheel rotation monitor; and Figure 3 shows a circuit diagram of the electron: 5 circuit within the monitor of figures 1 and 2.

Referring now to figure 1, there is shown a side view of part of a vehicle 20 comprising a body 21 supported on air springs 22 on bogies 24 (only one of 10 which is shown). The bogie 24 includes an H-frame 25 and two wheelsets 27, each wheelset 27 comprises two wheels 28 integral with an axle 29. At each end the axle 29 locates in a bearing in an axle box 30, the axle box 30 being connected by rubber springs 32 to the frame 25. A 15 horseshoe-shaped restraint plate 33 is bolted rigidly to each axle box 30, and a restraint stud 34 projects from the frame 25 through the ring so formed. The wheels 28 roll along a railway track 35. These features are conventional, and their details do not form part of the 20 present invention. On one wheel 28 a rotation monitor 36 is bolted to the end of the axle 29.

Referring now to figure 2, the rotation monitor 36 is a sealed unit that is bolted to the end of the axle 29 25 by bolts 38, after attaching an interface plate 37 to the end of the axle 29. The axle 29 may be hollow, as shown.

(With vehicles provided with in-board suspension the end of the axle is exposed, and the interface plate 37 takes the place of a cover plate on the end of the axle 29; 30 with vehicles with out-board suspension, as shown in figure 1, the end of the axle 29 may be accessed by removing a cover plate from the axle box 30.) The monitor 36 includes a generally cylindrical rigid housing 40 of glass-loaded resin sealed with a cover plate 42, 35 the housing 40 being coaxial with the axle 29. The housing 40 is generally cup shaped, with a base plate 43

at whose centre is a square recess in which a stainless steel stub axle 44 locates (which is therefore also coaxial with the axle 29). A ferrite ring 45 defining eight north poles alternating with eight south poles, 5 with an annular steel back plate 46, is moulded into the base plate 43 concentric with the stub axle 44. An annular steel plate 47 is connected by an aluminium disk 48 to the other end of the stub axle 44 to provide a low reluctance magnetic flux path between the poles of the 10 ferrite ring 45, the disk 48 having a square hole in which the end of the stub axle 44 locates. The disk 43 and the stub axle 44 are fixed to the base plate 43 by a bolt 49.

15 The stub axle 44 locates a roller bearing 50 which supports, via a concentric sleeve 52, a shallow cup shaped rotor 54 that fits within the housing 40. The rotor 54 is also of a rigid glass-loaded resin, and includes three electrical windings (not shown) embedded 20 in its base so that the windings are between the ferrite ring 45 and the steel plate 47. A steel block 55 is attached to the rotor 54 at the bottom (as shown). The bearing 50 would allow the rotor 54 to rotate freely about the stub axle 44. In practice, as the vehicle 20 25 moves the axle 29 rotates, so that the housing 40, stub axle 44, and the steel plate 47 all rotate together, while the asymmetrical weight distribution, due to the weight of the block 55, ensures that the rotor 54 does not rotate. The rotation of the poles of the ferrite 30 ring 45 relative to the windings in the base of the rotor 54 ensures that three phases of alternating electric voltage are induced in the windings. The open end of the rotor 54 supports a circular printed circuit board 60 carrying an electronic circuit 64 (shown in figure 3), 35 some components of the circuit 64 being shown diagrammatically; at least the heavier circuit components

are mounted on the lower half of the circuit board 60, augment the asymmetry in weight distribution.

The electronic circuit 64 is shown in more detail in 5 figure 3, to which reference is now made. The circuit 64 includes three connections Vr, Vy and Vb to the terminals of the electrical windings embedded in the rotor 54, the windings being connected in a triangular array linking these terminals. The terminals therefore provide three 10 phases of alternating voltage. The circuit 64 has the following sections: a power supply circuit 66; a battery 68; a pulse generating and shaping circuit 70; a processing integrated circuit 72 to count the pulses; and a radio transmitter/receiver 74 connected to an aerial 15 strip 76 on the outside of the circuit board 60. These sections are connected electrically between a ground line 78 and a electrical supply line 80. For testing and initial setup there is also a connector socket 76 to enable electrical signals to be supplied to various 20 different positions in the circuit 64.

The power supply circuit 66 receives the voltage signals from the connections Vr, Vy and Vb, these being rectified by diodes D, the maximum voltage being limited 25 by a zener diode Z. the maximum current being restricted by a current control unit 82 (e.g. LM317) in response to a measurement of the voltage across a resistor R1, the resulting DC current being smoothed by a capacitor C1 and supplied to the battery 68. The zener diode Z may for 30 example be arranged to restrict the voltage to 36 V; for vehicles that will not travel at high-speed (say above 100 kph) this may be omitted. The current control unit 82 is provided to ensure that the induced currents in the windings do not become so large as to cause the rotor 54 35 to rotate.

- 6 The voltage signals from the connection Vb are also used to generate pulses by means of the circuit 70, these signals being coupled via a capacitor C4 to an amplifier 84 (e.g. LM358) provided with back-to back clamping of 5 its inputs, the resulting voltage signal being supplied via a resistor R13 to a comparator 86 (e.g. LM358) whose other input is supplied with a fixed voltage from a potential divider Rl2 and R14. The output signal from the comparator 86 consists of a generally square wave 10 signal having eight cycles per rotation of the housing 40 relative to the rotor 54.

The output signal from the comparator 86 is supplied to the processing integrated circuit 72 along lead 88.

15 This may for example be a 28-pin integrated circuit such as 16F876/873. This is also provided with a clock signal from a ceramic resonator 90. The circuit 72 is arranged to count the total number of pulses, which corresponds to the distance travelled by the wheel of the vehicle 20, 20 and to store this information in a memory. It also may be arranged to determine the maximum speed at which the vehicle 20 has travelled, and to store this data also.

The processing integrated circuit 72 is connected to 25 the radio transmitter/receiver circuit 74 (e.g. BiM2-433-

64 manufactured by Radiometrix Ltd). In response to signals received via the aerial 76 from an external station, the circuit 72 provides data indicating the vehicle, and the stored data concerning distance and 30 speed, to the transmitter 74, which transmits this information via the aerial 76 to the external station.

It will be appreciated that the electronic circuit 64 may be modified in various ways, and may incorporate 35 additional sensors. For example it may incorporate a device to monitor the temperature of the axle 29. In a

modification the transmitter/receiver 74 is replaced by a transmitter circuit (not shown), receiver stations being installed adjacent to the railway track at a depot or station where the vehicle will stop, and the circuit 72 5 is arranged to cause transmission of data as described above whenever the vehicle 20 stops. If more complex calculations are required before the data can be transmitted, the processing integrated circuit 72 might be replaced by a microprocessor. There may also be 10 modifications to the mechanical design, for example the stub axle 44 might be integral with the base plate 43 rather than being a separate component.

Claims

((aim - 8 Claims

1. A wheel rotation monitor including a housing for mounting on a wheel of a vehicle, the housing enclosing 5 means for generating electricity, means for recording data representing the total number of rotations of the housing, and a transmitter for transmitting such data to a sensor external to the monitor.

10

2. A monitor as claimed in claim 1 wherein the housing incorporates a bearing, and the monitor comprises a freely rotatable monitoring element supported on the bearing, the monitoring element being asymmetrical in its weight distribution so that rotation of the housing does 15 not cause rotation of the monitoring element, the monitoring element incorporating means for detecting rotation of the housing relative to the element.

3. A monitor as claimed in claim 2 wherein the 20 electricity generating means comprises one or more magnet poles within the housing, and one or more coils in the monitoring element.

l

4. A monitor as claimed in any one of the preceding 25 claims wherein the rotation detecting means is at least part of the electricity generating means.

5. A monitor as claimed in any one of the preceding claims wherein means are also provided to restrict the 30 magnitude of the current generated by the electricity generating means.

6. A wheel rotation monitor substantially as hereinbefore described with reference to, and as shown 35 in, the accompanying drawings.