This invention relates to an electronic control system for the wheel axles o.f rail-mounted vehicles, especially railroad cars.

Neglected maintenance, as sporadic spot checks of the condition of the wheel axles , can have disastrous consequences for passengers as well as for rolling stock, caused by the tipping, derailing etc. of cars.

The present invention has the object of preventing such incidents. This object is achieved in that a transducer is attached to or adjacent each bearing box to continuously sense the vibrations of the bearing box and emits an electric signal corresponding to the vibrations to a signal processing unit common to all transducers on the same vehicle. Said unit is capable to distinguish individual fault, signals and their origin on the basis of different frequencies caused by wheel and bearing faults , and to pass information on the kind of fault as well as on the axle, on which the fault is located, to an indicating unit.

The measuring values used in the control system a-re the vibrations σccuring in the bearing boxes and arising from the contact of the wheel with the rail, from the play between wheel rim and hub disc, from defects in the bearings and/or from non--circular rim.

One embodiment of the invention is described in the following, with reference to the accompanying drawings, in which

Fig. 1 is a 'schematic view of an axle arrange- ment at a driving vehicle (locomotive) equipped with the system according to the invention, Figs. 2 and 3 are flow diagrams for the signal processing unit and, respectively, in- dicating unit comprised in the -equipment,

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and Figs. S and 6 are examples of block diagrams for fault determination and, respectively, fault indication without and, respectively, with microcomputer. In Fig. 1 four equal wheel pairs are shown, each comprising an axle A, which at each end carries a hub disc N and a rim R attached thereabout for rolling on the rail. The bearing box for each axle end is designated by L. At the embodiment shown, a transducer G in the form of an accelerometer (indicated merely as a dot), preferably of piezoelectric type, is rigidly attached directly on each bearing box.

The vibrations occuring on the wheel, axle and thereby on the bearing box of the vehicle when running are converted by the transducer G into an electric signal S with a frequency corresponding to the vibrations.

The eight signals S (one for each wheel) are passed to an electronic signal processing unit B common to all transducers on the vehicle, in which unit the signals are classified individually with respect to frequency. When in any of the frequencies a change beyond the established normal values arises and endures, the unit B determines the fault class by -means of an empirically established program. Information thereon and on the location (wheel in question) of the fault is pa.ssed in the form of a report signal R to an indicating unit I, which informs the driver on the situation.

When the driving vehicle propels one or several cars coupled thereto, as indicated to the right in Fig. 1, the driver also needs information on the car on which the fault is located. The coupled cars are equipped in the same way as the driving vehicle, except for the indicating unit, and all signal processing units in the car set are connected in series. Upon initiation by the indicating unit, an addressing signal is emitted through the entire car set, and in each processing unit the address is dated-up by one

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step. The ingoing address is stored in each signal processing unit and used as address for faulty axle.

Fig. 2 is a. schematic block and flow diagram for the signal processing unit B, which at the embodiment shown is ^* S of digital type. From the transducers G (only two are shown) the analogue signals S pass via amplifiers F to an analogue-digital converter A/D. The digital ^' signals from A/D are fed to a calculating unit K, and the resulting in¬ formation therefrom is sent, as described above, to the 10 indicating unit I, which also acts as address decoding unit and_ initiating unit for the infeed and outfeed of series data.

According to the diagram in Fig. 3, an output signal passes from a fault indicating and address unit to a dis- 15 play unit D for information of the driver, and a control unit C controls the function of the indicating unit.

The invention, according to the aforesaid, is based .on the observation that vibrations Θ-f---bearing boxes change their nature when faults arise, i.e. the natural wheel 20 frequency transferred to the bearing box is at faults in wheels or bearings shifted away from its. nominal value corresponding to faultless condition. It was, thus, observed that wheel rim faults (play) cause a distinctive increase in frequency, and a bearing fault _ tending to lock 2S the wheel yields a more distinctive increase.

Figs. 4 and 5 show examples of block diagrams for the detection of wheel rim play and wheel locking.

In Fig. 4 showing the arrangement for each wheel of the car, the output signal of the transducer G attached * 30 to the bearing box of the wheel passes via a combined band pass filter-amplifier BP + F, which filters off undue harmonics, to the parallel connected band pass filters BP1 and BP2, which are tuned for wheel rim faults and, respectively, wheel locking. From there, the 35 signals having different frequencies pass to the respective level indicators NI1 and Nl2,-whic are intended to permit passage of the signal first when -it exceeds a

certain amplitude or level N1 and, respectively, N2. A possibility for N2 of tapping reference level via an ampli¬ fier F connected to the output of the filter-amplifier 3P ÷ F and a filter circuit is indicated by dashed lines. The same applies in analogue manner to level N1. A signal permitted to pass then passes in each of said cases via a voltage divider to the base of a transistor T1 and, respectively, T2, the output signal of which at the terminal U1 and, respectively, U2 indicating rim fault and, respectively, locking is fed to a central computer or local computer for processing and indication.'

In Fig. S, which refers to an arrangement common to all wheels of a car and utilizing a micro-computer, the output signal from each transducer G (only one shown) passes via a band pass filter BP to an analogue-digital converter A/D, which via a data bus DB and an _. address bus A3 communicates with a micro-computer ,uD. The analogue signal from the converter A/D passes via an amplifier...F with automatic amplification control to the two band pass filters 3P1 and BP2, which as in the foregoing case are tuned for wheel rim faults and, respectively, wheel locking. The output signals of the filters are fed to an analogue gate AG. The output signal therefrom passes by control from the address bus AS to the converter A/D, which transduces the infor a- tion to the micro-computer ,uD via the data bus D3. On the basis of this information the computer sends output signals to existing indicato s for wheel faults and, respectively, bearing faults.

The invention is not restricted to the embodiment described above, but various modifications can be imagined within the scope of the invention. Accelerometers, for example, of a type other than piezoelectric can be used. Alternatively, the use of acusto-electric converters (microphones) for the electric representation of the vibrations can be imagined, which always are accompanied by sound phenomena. _ .

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