The invention relates generally to railroad friction modifying systems. More particularly, the invention relates to systems and methods for automatically detecting the health and functionality of a locomotive friction modifying system, as well as components thereof.
Locomotives used for heavy haul applications typically must produce high tractive efforts. The ability to produce these high tractive efforts depends on the available adhesion between the wheel and rail. Many rail conditions (especially wet), require an application of sand to improve the available adhesion. Therefore, locomotives typically have sandboxes on either end of the locomotives, and have nozzles to dispense this sand (both manually and automatically) to the rail on either side of the locomotive.
In the prior art, the sandboxes are periodically inspected to determine sand level. Based on the periodic inspection, the sandboxes are filled if needed. If sand runs out between inspections, however, there is no indication to the operator. Similarly, if a valve is not functioning or if a sand nozzle or any of the piping is blocked, sand delivery is adversely affected. Such problems can result in a locomotive not producing enough tractive effort and may cause train stall and undue delays for a whole railroad system. In the prior art, such problems are detected only at an inspection time. This is true for other prior art friction modifying systems as well.
Therefore, there is a need for an improved system and method for automatically detecting the condition of a locomotive friction modifying system, as well as components thereof. Such a system and method monitors and assesses the effects of attempted friction modifying applications, for the purpose of friction enhancement/reduction control, so as to determine if a friction modifying agent actually was delivered to the desired wheel-rail interface.
One aspect of the invention provides a system for assessing a health and functionality of a locomotive friction modifying system wherein the locomotive has a friction modifying applicator associated with a wheel of the locomotive for applying a friction modifying agent to a rail on which the wheel is traversing. The system comprises a sensor for detecting a predetermined operational condition of the locomotive. The system also comprises a controller associated with the sensor and responsive to input from the sensor for determining a per unit creep of an axle of the locomotive. The controller also determines a tractive effort of the axle of the locomotive and determines a friction modifying applicator state for the applicator associated with the axle. The controller further compares the determined per unit creep of the axle, the tractive effort of the axle and the state of the friction modifying applicator associated with the axle to a predetermined value indicative of the health and functionality of the locomotive friction modifying system. The controller provides an indication of the health and functionality of the locomotive friction modifying system.
In another aspect of the invention, a method is provided for assessing health and functionality of a locomotive friction modifying system wherein the locomotive has a friction modifying applicator associated with a wheel supported on an axle of the locomotive for applying a friction modifying agent to the rail on which the wheel is traversing. The method comprises determining per unit creep of an axle of the locomotive, determining a tractive effort of the axle of the locomotive, and determining a friction modifying applicator state for the applicator associated with the axle. The method further comprises comparing the determined per unit creep of the axle, tractive effort of the axle, and state of the friction modifying applicator associated with the axle to a predetermined value indicative of the health and functionality of the locomotive friction modifying system. The method also provides an indication of the health and functionality of the locomotive friction modifying system.
Although the following detailed description is, for the most part, limited to sanding systems, it is to be understood that the systems and methods of the present invention apply equally well to other friction modifying agents such as, air, steam, water, lubricating fluid, or oil and includes agents that increase or decrease friction or remove another friction modifying agent.
One way to assess the health of a locomotive sanding system is to recognize a change in friction that occurs when sand is introduced to the wheel/rail interface.
In order to detect the application of sand to the rail, it is not required to fully understand the precise nature of the change in adhesion curves as previously shown. Any change in the friction/creep characteristics associated with sand state changes signifies the effect of sand. For example, if the rail conditions were such that upon application of sand the available adhesion or friction was to be reduced, this would also be detectable.
Referring similarly to
Analyzing the effect of adhesion/creep changes associated with manual, trainline, and/or automatic sand on each wheel, depending on the axle and direction of travel, provides an indication of the effectiveness of the sanding system. Such information can also be used to determine the state/health of the sandboxes, the sand valves, and/or the sand nozzles. Creep of an axle is the difference in speed of a wheel associated with the axle and the locomotive. Per unit creep is the ratio of creep to locomotive speed. Per unit creep of each axle “n” is calculated (sometimes identified herein as “creep_pu[n]”). The tractive effort of each axle (sometimes identified herein as “te[n]”) is obtained from torque produced by each motor and the knowledge of wheel diameter and gear ratio. These te and creep calculations and changes associated with a sanding state change are used to determine the health of the sanding components of each truck, in each direction and for each sandbox.
Table 1, as provided at the end of the specification, provides a list of potential failure modes that correlates those modes to the sand nozzles affected by the failure modes. For example, if the front truck sandbox is closed (blocked), then nozzles 102, 104, 106, and 108 are affected.
Table 2, as provided at the end of the specification, identifies relationships between phenomena detected and the potential failure modes causing each detected phenomenon. For example, if axle 1 friction indicates no sand in the forward direction, then the reasons could be (a) the front truck manual air valve is closed, (b) the front truck forward sand solenoid valve is failed, or (c) the front truck sandbox is blocked.
The front truck forward system 702 analyzes the data and outputs the sand health for the front truck forward (FTF) 734. The front truck reverse (FTR) system 704 analyzes the data and outputs the sand health for the front truck reverse 736. Both of these are provided inputs to the front sandbox health determination system 754 that outputs the sand health front box 738. Similarly, the rear truck reverse (RTR) system 706 analyzes the data and outputs the sand health for the rear truck reverse 740. The rear truck forward (RTF) system 708 analyzes the data and outputs the sand health for the rear truck forward 742. Both of these are provided inputs to the rear sandbox health determination system 756 that outputs the sand health rear box 744.
In
Six sand health state integrators are shown in
Similarly,
In addition to these effects, a single sand nozzle failure can cause a torsional vibration due to an unequal adhesion/friction coefficient between the left and right side wheel rail interface. The axle immediately following the failed sand nozzle typically encounters this phenomenon more than any other axle. Such torsional vibration causes resonance of the wheel/axle set at its natural frequency. This resonance can be detected by observing the frequency content in the torque or speed feedback of that axle and can directly indicate a nozzle health. Any change in resonance torque or speed immediately following a sand command state change is used to determine the health of the sand nozzles in front of the axle.
When introducing elements of the present invention or the embodiment(s) thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This application claims priority to U.S. Provisional Patent Application No. 60/391,743, filed on Jun. 26, 2002, the entire disclosure of which is incorporated herein by reference.
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Number | Date | Country | |
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20040060375 A1 | Apr 2004 | US |
Number | Date | Country | |
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60391743 | Jun 2002 | US |