The invention pertains to wheels count of any railway vehicle that passes on a railway track section with an improved fail safe feature.
Currently a system referred to as Digital Axle counter is used to count the number of wheels that passes over a railway track section and has two parts to it - entry and exit (each of the part contains both Tx and Rx units). The systems works on a principle of mutual inductance. The number of wheels is counted at the entry of the designated track section and again at the exit of the track section. When the count is equal it is then declared that the train has passed that railway section.
The reliability of the prediction of the train passage, consequently counting of wheels, in the above system is likely be affected by the change in atmospheric conditions. The above system also does not distinguish the absence of the train and a derailment if any within the entry and exit points. The above system is also designed to work at only two discrete points on a track section and is not capable of continuous track section utilization.
To overcome the above limitation of the system in vogue, a new improvised device with novel characteristics is designed, having the following distinct advantages.
1. It is independent of the atmospheric condition changes.
2. It consumes less power
3. It can also detect the absence of a train on given railway track section
4. It can also detect the direction of the train movement
5. It can detect the speed of the train when it passes over the track section
Accordingly, the present invention consists of necessary electronic circuitry that is capable of improving the reliability of prediction of the wheel counting mechanism, with built in safety features and comprising (Fig 2) of a transmitter module (5), a receiver module (6), a power supply module (7), a health monitoring module (8), and a wheel count logic circuitry (9) with a predetermined characteristics and connected by a copper cable.


Now the invention will be described in more detail with reference to the accompanying drawings, bringing out a number of embodiments of the arrangement according to the invention
Fig 1- A general arrangement of the current system as deployed in the railway track section.
1. Transmitter
2. Receiver
3. Raill
4. Rail 2
FIG 2 - General arrangement of the deployment of the present invention in a railway track section
5. Transmitter
6. Receiver
7. Power supply
8. Health monitoring
9. Wheel count logic
10. Transmitter terminal 1
11. Transmitter terminal 2
12. Receiver terminal 1
13. Receiver terminal 2
FIG 3 - A general arrangement of the deployment of the present invention in a railway track section when it is occupied by a train.
14. First wheel
15. Second wheel
16. Bogie
17. Transmitter terminal 1
18. Transmitter terminal 2
19. First wheel set
20. Transmitter terminal 1
21. Transmitter terminal 2
22. First wheel set


23. Transmitter terminal 1
24. Transmitter terminal 2
25. First wheel set
26. Second wheel set

27. Transmitter terminal 1
28. Transmitter terminal 2
As shown in fig 1, device known as digital axle counter is used to count wheels of a railway train, which passes over a specified length of track section. The digital axle counters consist of transmitter (1) and receiver (2) that is connected on each side of the rail (4). They work on the principle of mutual inductance and largely depend on permeability of the air. The phase angle of the received signal will be compared with transmitted signal to count the wheels. The received signal phase angle will depend on the permeability of air and which in turn depends on the atmospheric conditions, leading to a possible error in counting.
Fig 2, describes the details of our invention wherein it is used to count the number of wheels that pass over a railway track section under all atmospheric conditions and detect the absence of a train over the specified railway track section with built in safety. The fail safe wheel counting device typically consists of a transmitter (5) and a receiver (6). The transmitter (5) transmits the signal at one end of the track (10) (11) and receives the signal at other end of the track (12) (13) in the specified area. The received signal will be compared against a predefined threshold value, provided in the hardware circuitry to judge the passage of a plurality of wheels over a predefined point.
FIG 3, wherein an improved fail-safe wheel counting device as per our invention is shown in a deployment mode and is capable of continuously monitoring the transmitter voltage, receiver voltage and transmitter current. The transmitted current and receiver voltages are compared against a predefined threshold level, provided in the form of hardware circuitry, to judge the number of wheels passing over a track section. The receiver voltage shall be below the threshold level when the track circuit is electrically short through the train wheel set. When the first wheel set (14) of a bogie (16) is approaching the transmitter points (17) (18), the transmitter current tends to increase. The current will be at peak when the first wheel set (19) is exactly on the transmitter points (20) (21).


The transmitter current tends to decrease when the first wheel set (22) passes away from the transmitter points (23) (24). The current will be least when the center distance between first (25) and second (26) wheel set is equal from transmitter point (27) (28).
As the bogie is running forward on the track, the above-mentioned process continuous at the transmitter point. Hence the current will be pulsated behave as a regular pattern as and when the wheel set is getting close to or passing away from the transmitter point. The output pulse is then used to measure the number of wheels passing over the track circuit. The amplitude of pulse is depends on the impedance of the rails and transmitter signal frequency.
The transmitter current signal pulse fed to passive filter that allows only specified band of frequencies and attenuate other frequencies including DC signal. The filter output is amplified with required gain and then compared with predefined threshold value, provided in the hardware circuitry. The fail-safe comparator output is normally low when track is vacant and pulsating at each wheel movement on the transmitter point. Each pulse represents one wheel. Micro controller based logic circuit provides as a part of the measuring unit will count such pulses and communicate to a remote computer
The wheel count logic circuit provided in the said device under our invention starts functioning only when receiver voltage is below the threshold level and transmitter current is above the threshold level.
Although the invention has been described in considerable detail with particular reference to certain preferred embodiments, thereof, variations and modifications can be effected within the spirit and scope of the invention as described herein above and as defined in the appended claims.

We claim
1) An improved fail safe device to detect number of wheels over a railway track
section comprising of transmitter module, receiver module, health monitoring
module, a power supply module, wheel counting logic module and is capable of
functioning independent of atmospheric conditions with a provision to calculate
the train speed & direction and provided with a built in fail safe mechanism.
2) An improved fail safe device as claimed in claim 1, the transmitter module with
high immunity to the electrical interferences comprising of an electrical
modulator, amplifier and filters.
3) An improved fail safe device as claimed in claim 1, the receiver module with
high immunity to the electrical interferences comprising of an electrical
demodulator, fail safe comparator and filters.
4) An improved fail safe device as claimed in claim 1, the health monitoring
module comprising of an electric convertors, counters, wireless communication
circuitry and data storage devices.
5) An improved fail safe device as claimed in claim 1, the power supply module
with high immunity to the electrical interferences comprising of an electrical
rectifiers, switches, isolation transformers, filters, feed back and control
hardware.
6) An improved fail safe device as claimed in claim 1, the wheel counting logic
circuit module with high immunity to the electrical interferences comprising of
an electrical filter, amplifier and counters.
7) An improved fail safe device as claimed in claim 1, provision exists by means of
suitable circuitry to monitor the frequency of changes in the receiver voltage
along with the changes in the transmitted current which in turn is capable of
deriving the train speed at an instant of time.


8) An improved fail safe device as claimed in claim 1, provision exists by means of suitable circuitry to monitor the frequency of changes in the receiver voltage along with the changes in the transmitted current which in turn is capable of differentiating the normal train wheels from the trolley wheels.
9) An improved fail safe device as claimed in claim 1, provision exists by means of suitable circuitry to monitor the frequency of changes in the receiver voltage along with the changes in the transmitted current which in turn is capable of detecting the direction of train entering in to the railway track section.
10) The device according to any one of the claims 1 to 9 substantially as herein
described with reference to and as shown in FIG 1 to 3 of the accompanying
drawings.

Mr Bopparaju Surendranath. General Manager
Date: 09-05-2008