Patent Application
20080147256
The present invention relates to control systems for locomotive consists and has particular utility in controlling horsepower in such consists.
The horsepower output of freight locomotives has increased in recent history, often producing in the range of 4000-6000 Hp. The advantages of a higher output are many and well known, including the ability to carry a similar load with fewer locomotives, and a higher fuel efficiency. One disadvantage of higher output locomotives is that, in order to comply with existing interchange standards, the horsepower is controlled using eight throttle or “notch” positions and, therefore, the incremental increase in horsepower per notch setting becomes greater as horsepower per unit increases. Table 1 below illustrates approximate horsepower output for each throttle setting for a typical 4000 Hp locomotive.
It can be seen from table 1 that the step change in horsepower as the operator moves from one throttle setting to the next can be relatively significant. For example, in moving from notch 6 to notch 7, an additional 704 Hp is added. The step change is, predictably, even more significant with higher horsepower locomotives.
In a locomotive consist, where two or more locomotives are connected so as to operate as a single overall unit, the step change in horsepower output as the operator changes throttle settings is even more pronounced as shown in Tables 2 and 3 below.
The above tables exemplify the approximate step increases for a 4000 Hp locomotive and it can be appreciated that different models and combinations will result in different settings. However, it can be seen that as more and more locomotives are combined in a consist, the coarseness of the horsepower control becomes more evident.
It is therefore an object of the following to obviate or mitigate the above described disadvantages.
In one aspect, there is provided, a method for controlling horsepower output in a consist of at least two locomotives comprising receiving an input indicative of a requested incremental change in horsepower; determining a current horsepower output for the consist and a current notch combination for the at least two locomotives generating the current horsepower; determining a next notch combination for the at least two locomotives in the direction of the incremental change having associated therewith, an expected horsepower output; determining a target horsepower output which is between the expected horsepower output and the current horsepower output according to the incremental change; referencing a set of one or more transitional horsepower outputs at alternative notch combinations and determining a desired one of the alternative notch combinations having a corresponding transitional horsepower output which is within a predetermined range of the target horsepower; and adjusting throttle notch positions in each the at least two locomotives according to the desired one of the alternative notch combinations.
In another aspect, there is provided a computer readable medium comprising computer executable instructions thereon for causing a processor in a control system to perform the above method.
In yet another aspect, there is provided, a system for controlling horsepower output in a consist of at least two locomotives, the system comprising a controller connected to each the at least two locomotives and capable of controlling notch positions thereof, the controller comprising a processor configured to execute computer readable instructions to cause the controller to, receive an input indicative of a requested incremental change in horsepower; determine a current horsepower output for the consist and a current notch combination for the at least two locomotives generating the current horsepower; determine a next notch combination for the at least two locomotives in the direction of the incremental chance having associated therewith, an expected horsepower output; determine a target horsepower output which is between the expected horsepower output and the current horsepower Output according to the incremental change; reference a set of one or more transitional horsepower outputs at alternative notch combinations and determine a desired one of the alternative notch combinations having a corresponding transitional horsepower output which is within a predetermined range of the target horsepower, the set being accessible to the controller; and adjust throttle notch positions in each the at least two locomotives according to the desired one of the alternative notch combinations.
An embodiment of the invention will now be described by way of example only with reference to the appended drawings wherein:
Referring to
When the throttle handle 12 is placed in the idle position 14, no tractive effort is generated by the locomotive. Notch 8 provides the maximum horsepower output for the locomotive. Notch 1 through notch 7 are interval steps in horsepower between zero (0) and maximum horsepower achieved by selecting notch 8.
An operator in the lead locomotive 20 controls all the locomotives in the consist 18 (in this example two) using the control stand 13. The lead locomotive 20 is connected electrically to the trailing locomotive 22 via a group of cables known as a trainline 24. Electrical signals generated by the control stand 13 for the control of the locomotives 20, 22 are paralleled with the cables in the trainline 24. It is generally accepted that every modern locomotive has a trainline 24 that conforms to standards established by applicable authorities. Performance measures such as locomotive direction, dynamic braking effort and throttle settings are typically controlled via the trainline 24. Traditionally, the trailing locomotive 22 is controlled by responding to the same commands as the lead locomotive 20 via the trainline 24.
For example, when the operator changes the throttle handle position from notch 2 to notch 3 in the lead locomotive 20, the throttle position in the trailing locomotive 22 also changes from notch 2 to notch 3. This leads to the coarseness described above and in particular exemplified in table 2 where the step increase from notch 2 to notch 3 is 1000 Hp. It can be appreciated that for a three-unit consist, the step increase is even coarser as shown in table 3.
It can be appreciated that the large step increases can be detrimental to fuel economy as, often, more horsepower than is required is output. In these situations, the operator may be required to cycle between two different notch positions 16 in order to achieve a certain overall average speed. A consist controller 26 may be used with the consist 18, which individually selects throttle positions for each locomotive 20, 22 in the consist 18. The controller 26 may be used to achieve different levels of horsepower output and/or to choose combinations that optimize fuel efficiency.
Preferably, the controller 26 stores a fuel consumption profile of every locomotive model that it may need to interface with, and from these profiles, a database is developed with every possible combination of throttle setting as exemplified in
In operation, when the operator moves the throttle handle 12 to a desired notch position 16, the controller 26 calculates the horsepower that is being requested for that notch position 16. The controller 26 may then review the database for every possible throttle combination that can achieve this targeted horsepower within a pre-determined range. From this “short list” of possible combinations, the corresponding fuel efficiencies are reviewed, and the most fuel efficient combination is then typically chosen. The combination indicates a notch position 16 for each locomotive (20, 22), and the controller 26 then instructs each locomotive 20, 22 individually. In some cases, each locomotive 20, 22 operates at the same notch position 16, and in other cases each locomotive 20, 22 operates at a different notch position 16. Details of such a fuel optimization system are provided in U.S. Pat. No. 4,344,364 to Nickles et al. published on Aug. 17, 1982, the contents of which are incorporated herein by reference.
The bolded lines in
For example, as shown in tables 2 and 3, there is a coarse granularity in horsepower control when two or more locomotives are combined. Referring to table 2, when changing from notch 6 where the consist 18 outputs approximately 5236 Hp, to notch 7 where the consist would then output approximately 6,734 Hp, an increase of 1408 Hp or approximately 26.4% can be experienced. Similarly, referring in particular to table 3, the same throttle position change results in an increase of 904 Hp (1810 Hp to 2714 Hp) or approximately 500%. As noted above, due to these large step increases (and similar decreases), the operator may need to move back and forth between two throttle positions in order to maintain the desired speed of the locomotive.
It has been recognized that in most cases, there are several intermediate or transitional power options available for the consist between each bolded notch combination in table 4 and, thus, taking advantage of these combinations can give the operator finer control over the output of the consist 18. For example, there are four (4) intermediate or transitional power settings between notch 6 and notch 7. In particular, between lines 70 and 77, of the eight combinations, four pairs are identical as they are mirror images of each other, e.g. notch 3-notch 4 and notch 4-notch 3.
It has also been recognized from
For example, making reference to
Referring again to the table in
Accordingly, by taking advantage of the full range of throttle combinations available and utilizing a flexible tolerance range, a finer horsepower control can be achieved, as well as higher fuel efficiencies.
In order to take advantage of the full range of throttle combinations, a consist controller 126 comprising a fractional horsepower request can be used as shown in
The function keys 34 may provide directional/positional type functions or actuation functions. The operations performed by the function keys 34 shown in
The interface 30 can be used by the operator to perform a set-up procedure where the operator establishes the models of the locomotives (20, 22) in the consist 18 so that the appropriate decisions can be made to, e.g. maximize the potential fuel efficiency. Once set up, the operator can perform his or her duties as normal. The controller 126 can direct the trainline 24 and lead locomotive 20 throttle positions 16 automatically, based on the horsepower targets associated with the chosen throttle handle position 16 (at the control stand 13), and the potential fuel efficiency improvements according to the table shown in
The display 32 can be used to present to the operator the targeted horsepower as requested by the actual throttle position 16, as well as the actual horsepower being produced by the consist 18 based on the throttle settings for all locomotives in the consist 18.
In order to provide finer control over the horsepower output, in this example, a fractional increase button 52 and a fractional decrease button 54 are provided. The fractional increase button 52 can be used to request a fractionally higher horsepower than what is currently being output according to the controller's settings (and with respect to the difference between this value and that for the next throttle setting 16), and the fractional decrease button 54 can be used to request a fractionally lower horsepower. The result of the request would be an adjustment of the horsepower target that is used by the controller 126 by a requested incremental change, either up or down. It will be appreciated that the increase button 52 and decrease button 54 shown in
In this context, fractional increase and decrease refers to a step increase that would lie somewhere in between two consecutive notch positions. For illustrative purposes, the following examples use a “half” (½) fractional increase/decrease, however, it will be appreciated that any other fraction, and any number of corresponding fractional steps can be used to provide even finer horsepower control. The fractional increases and decreases can be used to avoid cycling up and down between notch positions 16, providing a smoother transition on ramp up or ramp down, selecting a better fuel efficiency, or any other reason where the operator would like to take advantage of the other combinations that can be achieved using the controller 126. It will be appreciated that any incremental change, whether or not a fractional step can also be used.
Referring to
The controller 126, when operating normally, would then determine if the increase button 52 has been selected at step 202. If the increase button 52 has not been selected, then the controller 126 then determines if the decrease button 54 has been selected. If the decrease button 54 has not been selected, then the controller 126 determines that normal operations should resume. In general, normal operations occur until receiving an input indicative of a requested incremental change in horsepower, e.g. by way of selection of the buttons 52, 54. If the decrease button 54 has been selected, sub-routine A is performed, which is shown in
If instead the increase button 52 has been selected, the controller 126 then determines if the existing or current horsepower target is a full or fractional (e.g. half) setting at step 206. For example, if the increase or decrease buttons 52, 54 have already been chosen, then the horsepower target would have already been fractionally adjusted and, as such, would lie in between two consecutive notch settings 16, namely the current notch setting and a next notch setting. If the current horsepower target is a half setting, the controller 126 then determines if the “half-notch” setting (represented by fractional target) is below the existing throttle handle position at step 208. This would have occurred if, previously, the operator had selected a fractional decrease by selecting the decrease button 54. If the half setting is below the existing throttle position 16, then the target horsepower would be reset according to the throttle position 16 at step 210 and normal control resumes.
For example, with half notch settings, if the user first decreases the target to halfway between two notch settings to decrease horsepower, but later begins to climb a grade and needs more horsepower, the next highest “half-notch” is a regular notch position 16 and thus by pressing the increase button 52, the target for the selected notch position 16 is restored. This avoids the operator having to move the throttle handle 12 out of and then back into that desired notch position 16 to re-establish the normal target setpoint. It will be appreciated that both methods for resetting the target horsepower can preferably be used to accommodate either case.
At step 208, if the half notch setting is determined to not be below the existing throttle position 16, then an error message or alert is preferably provided at step 212 and no settings are changed. In this way, the operator is alerted when they are instead supposed to select the next throttle position 16 as they would have already increased the target for the selected notch setting 16. It will be appreciated that this step is preferable where physical control of the throttle handle 12 is required and, if automatic control of the throttle handle were to be permitted, the half notch settings could be used for fractional steps which would then include the normal full throttle settings 16.
If the existing throttle target is a full setting, then the controller 126 next determines if the existing notch position 16 is notch 8 at step 214. If the throttle position 16 is notch 8, then a similar alert is provided at step 212. Since notch 8 is the maximum horsepower, naturally, a step increase would not be permitted. If the notch position 16 is something other than notch 8, then the controller 126 next determines if the half-way (fractional) point between the existing horsepower setting and the next highest horsepower setting (the next notch in this example) at step 216. Once the half-way point is determined, the value is used to establish a new horsepower target for the controller at step 218.
Referring to
In this example using half notches, the current setpoint would be 3960 Hp and the next setpoint would be 5326 Hp if notch 6 were to be selected. The mid-point between these values is 4643 Hp (new target horsepower) and the new range for fuel optimization would be approximately 4410-4875 Hp. According to
Turning back to
If at step 222 the controller determines that the half notch setting is in fact below the current throttle handle position 16, then an alert or error message is provided at step 226, similar to step 212 in
When the throttle handle 12 is at any non-idle position 16, the controller 126 determines that a step decrease can be achieved and determines the half-way point between the existing horsepower setting and the next lowest horsepower setting at step 230, and establishes a new horsepower target for the controller 126 at step 232 similar (but opposite) to that described above for the fractional increase. Once the new target is set, the logic proceeds at point B to the main routine in
When the fuel efficiency is not being optimized, it is clear from the above principles that the half notch setting would select a new target of 4643 Hp (at a notch 2-notch 6 combination), which provides finer control than increasing output to 5326 Hp by selecting notch 6. Therefore, the operator is given the option of using a finer control, which can provide smoother transitions, utilize more fuel efficient combinations and avoid repeated cycling between notch positions 16 to balance a desired average speed. It will be appreciated that by providing additional fractional steps such as ¼, 2/4, ¾ or ⅓, ⅔ etc., even finer control can be achieved.
It will also be appreciated that the logic shown in
As an additional feature, shown in
In a preferred embodiment, the controller 126 provides both the increase/decrease buttons 52, 54 and the ability to select from all options as shown in
Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.
This application claims priority from U.S. Provisional Application No. 60/870,506 filed on Dec. 18, 2006, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60870506 | Dec 2006 | US |
