SYSTEM FOR MONITORING A WHEEL-RAIL CONTACT FORCE

Abstract

A system for monitoring a wheel-rail contact force, the system providing a measuring unit for measuring a vertical acceleration of a wheel being connected to a bogie. The wheel is configured to run on a rail. The system includes a calculation unit for simulating a wheel-rail interaction using the measured vertical acceleration and for calculating a wheel-rail contact force based on the simulated wheel-rail interaction. Also, a method for the same.

Claims

1. System for monitoring a wheel-rail contact force, the system comprising: a measuring unit for measuring a vertical acceleration of a wheel being connected to a bogie, wherein the wheel is configured to run on a rail, and wherein the system comprises a calculation unit for simulating a wheel-rail interaction using the measured vertical acceleration and for calculating a wheel-rail contact force based on the simulated wheel-rail interaction.

2. System according to claim 1, wherein the measuring unit is adapted to measure the acceleration of the wheel by measuring the acceleration of an axle box being connected to the wheel.

3. System according to claim 2, wherein the measuring unit comprises an acceleration sensor.

4. System according to claim 1, wherein the calculation unit is adapted to transform the vertical acceleration of the wheel into a vertical velocity of the wheel.

5. System according to claim 1, wherein the calculation unit is adapted to simulate a two-mass model of a quarter bogie.

6. System according to claim 5, wherein the two-mass model is based on a sprung mass of the bogie and a coach, primary suspension parameters, an unsprung mass of the wheels and a wheel-rail contact stiffness.

7. Method for monitoring a wheel-rail contact force, the method comprising: measuring a vertical acceleration of a wheel being connected to a bogie, wherein the wheel runs on a rail, and wherein the method comprises simulating a wheel-rail interaction using the measured vertical acceleration and calculating a wheel-rail contact force based on the simulated wheel-rail interaction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The figures show:

[0035] FIG. 1: a perspective view of a part of a bogie being arranged on rails;

[0036] FIG. 2: a schematic block diagram of a system for monitoring a wheel-rail contact force of the bogie of FIG. 1; and

[0037] FIG. 3: a schematic diagram of the mass model used in the system of FIG. 2.

[0038] In the following same or similar functioning elements are indicated with the same reference numerals.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0039] FIG. 1 shows a part of a bogie 1 which comprises four wheels 2 being situated on rails 4. The bogie 1 is a bogie of a rail vehicle that runs on the rails 4. The wheels 2 are supported by an axle box 6 being coupled via an axle 8.

[0040] In order to monitor a wheel-rail contact force, a system 10 (illustrated in FIG. 2) may be used for measuring a vertical acceleration of the wheel 2. Therefore, one acceleration sensor 12 is arranged at each wheel 2.

[0041] FIG. 2 shows a schematic block diagram of the system 10 for monitoring the wheel-rail contact force. The system 10 comprises a measuring unit 16, which may include the sensor 12 as shown in FIG. 1. The sensor may be, for example, one acceleration sensor 12 per wheel 2.

[0042] The system 10 further comprises a calculation unit 18. The calculation unit 18 may receive the measured vertical acceleration as input signal 26 and may simulate a wheel-rail interaction using the measured vertical acceleration. Further, the calculation unit 18 may calculate the wheel-rail contact forces based on the simulated wheel-rail interaction.

[0043] For simulating the wheel-rail interaction, the calculation unit 18 may use a simulation model, as shown in FIG. 3.

[0044] The simulation model 20 as shown in FIG. 3 uses a sprung mass 22, which is the sprung mass of the bogie 1, primary suspension parameters k.sub.2 and c.sub.2, an unsprung mass 24, which is the mass of the wheelset, and a wheel-rail contact stiffness. Further, the simulation model uses the measured vertical acceleration. Based on these parameters, the simulation model 20 simulates a behavior of the bogie 1. This simulation model 20 may be used to determine the wheel-rail contact forces F1. For this purpose, only one measured input parameter 26, i.e. the vertical acceleration, is needed.

[0045] In a first step, the calculation unit 18 transforms the measured vertical acceleration of the wheel 2 into a vertical velocity of the wheel 2. Thus, the simulation model of FIG. 3 uses as input the vertical velocity of the wheel 2 which is based on the measured acceleration.

[0046] Based on the 2-mass model and the dynamic parameters of the bogie 1 as well as the measured signal, the calculation unit 18 calculates a wheel-rail contact force F1 based on a simulated wheel-rail interaction which may be forwarded for further processing as output 28. This information may then be used to monitor the wheel-rail contact forces and to identify defects on the rails or the wheels.

[0047] Using the above described system and method, it is possible to provide a cheap wheel-rail contact force condition monitoring as only one parameter, i.e. the acceleration, needs to be measured. Such a monitoring forces at a wheel-rail contact may be used for identifying potentially harmful corrugations that may require repair or maintenance.