US 20070272116 A1
A method of using one or more electric locomotive and energy storage car combinations to assist a train consist up an uphill climb, the one or more electric locomotive and energy storage car combinations each having one or more diesel electric locomotives and one or more separate energy storage cars, including adding the one or more electric locomotive and energy storage car combinations to the train consist prior to an uphill climb; using the one or more electric locomotive and energy storage car combinations to assist the train consist up the uphill climb; and removing the one or more electric locomotive and energy storage car combinations from the train consist after the uphill climb. The one or more electric locomotive and energy storage car combinations are added to a train consist traveling downhill to assist with the downhill slowing through dynamic braking regeneration that is used to recharge the energy storage of the one or more separate energy storage cars.
1. A method of using one or more electric locomotive and energy storage car combinations to assist a train consist up an uphill climb, the one or more electric locomotive and energy storage car combinations each having one or more diesel electric locomotives and one or more separate energy storage cars, comprising:
adding the one or more electric locomotive and energy storage car combinations to the train consist prior to an uphill climb;
using the one or more electric locomotive and energy storage car combinations to assist the train consist up the uphill climb;
removing the one or more electric locomotive and energy storage car combinations from the train consist after the uphill climb.
2. The method of
3. The method of
4. The method of
5. The method of
6. The method of
7. The method of
8. The method of
9. The method of
10. The method of
11. The method of
12. A method of using one or more energy storage cars to assist a train consist up an uphill climb, the consist having one or more electrically propelled locomotives for primary propulsion power, comprising:
adding the one or more energy storage cars to the train consist prior to an uphill climb;
using the one or more energy storage cars to supply additional power to the one or more dual mode locomotives to assist the train consist up the uphill climb;
removing the one or more energy storage cars from the train consist after the uphill climb.
13. The method of
14. The method of
15. The method of
16. The method of
17. The method of
18. The method of
19. The method of
20. The method of
21. The method of
22. The method of
This application is a continuation-in-part application of U.S. patent application Ser. No. 11/420,064, filed May 24, 2006. This application claims the benefit of this prior application and this prior application is incorporated by reference herein as though set forth in full.
The field of the invention relates to locomotive assists to assist the propulsion of freight trains up long grades.
Railroad operations often use one or more additional diesel locomotives to assist the propulsion of freight trains up long grades. At the top of the grades the locomotives are uncoupled from the train at a switch yard or siding and sent back to the bottom of the grade to assist additional trains requiring assistance up the long grades.
A problem with these diesel locomotives used to assist the propulsion of freight trains up long grades is that the diesel locomotives consume a lot of diesel fuel and pollute the environment during this frequently repeated process.
Accordingly, an aspect of the invention involves recycling freight train braking energy from downhill grades to use as an assist to the propulsion of freight trains traveling uphill. Rather than using one or more diesel locomotives to assist moving the train uphill, the method of this invention uses one or more electric powered locomotives with one or more attached energy storage car(s) to provide the electric power. The energy storage car(s) contain electrical energy storage, e. g., a battery pack, which is charged by the electric motor/generators of the locomotive from a previous descent of the grade. At the top of the grade the additional electric locomotives with attached energy storage car(s) are coupled to a descending train to provide dynamic braking and charge the energy storage device.
Another aspect of the invention involves a method of using one or more electric locomotive and energy storage car combinations to assist a train consist up an uphill climb. The one or more electric locomotive and energy storage car combinations each have one or more diesel electric locomotives and one or more separate energy storage cars. The method includes adding the one or more electric locomotive and energy storage car combinations to the train consist prior to an uphill climb; using the one or more electric locomotive and energy storage car combinations to assist the train consist up the uphill climb; and removing the one or more electric locomotive and energy storage car combinations from the train consist after the uphill climb.
A further aspect of the invention involves a method of using one or more energy storage cars to assist a train consist up an uphill climb, the consist having one or more electrically propelled locomotives for primary propulsion power. The method includes adding the one or more energy storage cars to the train consist prior to an uphill climb; using the one or more energy storage cars to supply additional power to the one or more dual mode locomotives to assist the train consist up the uphill climb; and removing the one or more energy storage cars from the train consist after the uphill climb.
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of this invention.
With reference to
In the embodiment shown, the passive rail car 110 is a Comet V commuter rail car including multiple axles 120 with wheels 130 on opposite ends of the axles 120 and a friction braking system attached to multiple axles. The axles 120 rotate with rotation of the wheels 130. In the embodiment shown in
The braking regeneration system 100 may include a gear box 140 and a motor/generator 150 for each axle 120, a single dual-inverter/controller 160 per truck 135 (per two axles 120), a single energy storage 170 per rail car 110, a single auxiliary power inverter 180 per rail car, a single set of braking resistors 190 per truck, and a single control computer 200 per rail car 110. In alternative embodiments, one or more of the number of trucks, axles, passive rail cars, braking regeneration systems, components of the braking regeneration system, and/or other elements described herein may vary from that shown and described herein. For example, but not by way of limitation, in an alternative embodiment, the braking regeneration system 100 includes one larger generator/motor incorporated on one axle 120 per rail car 110 instead of four smaller gearbox/motor/generator systems, one on each axle 120 of the rail car 110.
The gear box 140 is mechanically connected to the axle 120. The gear box 140 transfers torque between the axle 120 and the motor/generator 150. At the same time as the gear box 140 provides a speed reduction to match the motor rpm to the axle shaft rpm, the torque increases by the same ratio as the speed reduction. In another alternative embodiment any required rpm speed reduction occurs in the motor connection to the axle 120 and a separate gear box 140 is not required. In yet other alternative embodiments the gear box 140 may include a clutch, multiple gears and a transmission. The single dual-inverter 160 controls both axle drive motor/generators 150 on the truck 135 and performs the power flow switching for the operation of the energy storage 170 and the braking resistors 210. The motor/generator 150 along with the dual-inverter 160 can be Siemens ELFA components that are used on electric and hybrid-electric heavy-duty vehicles or other manufacturer's components used on electrically propelled trains. The motor/generator 150 generates energy during braking regeneration and powers the wheels 130 via the gear box 140 and axle 120 during an acceleration mode. In the embodiment shown, the motor/generator 150 is a combined, integrated motor and generator; however, in an alternative embodiment, motor/generator 150 includes physically separated motor and generator. The energy storage 170 includes a central energy storage system, which provides the energy storage for the energy needs of the whole rail car 110. In alternative embodiments, one or more other types of energy storage systems are used such as, but not limited to, one or more or a combination of different battery chemistries, ultracapacitors, flywheels, or springs. A single inverter and power conditioning module 180 provides for the power needs 210 (e.g., rail car emergency power, rail car accessory power, cooling pumps 220) on the rail car 110. A typical commuter rail car accessory power draw may include lighting, heating, ventilation, air conditioning (HVAC), and plug-in power for electronic devices. The inverter and power conditioning module 180 may replace all or part of the power normally supplied by the head-end power (HEP) from the train locomotive.
The motor/generator 150, the dual-inverter 100, the energy storage 170, the auxiliary power inverter 180, and the braking resistors 190 may be liquid cooled. The liquid cooling loop, not shown, consists of liquid coolant, typically 50/50 water/ethylene glycol, a heat exchanger radiator with electric fans, and coolant pumps 220 to circulate the coolant. One or more coolant loops may be used on the rail car to manage the temperature of the electric power components 150, 160, the energy storage 170, the power conditioning module 180, and the HVAC system.
One of the cooling loops may include the braking resistors 190 that may serve two different functions. The braking resistors 190 are high power electrical resistors that dissipate power by heating a circulating fluid. The coolant heat may be dissipated in one or more of a heat exchanging radiator that radiates heat to the air passing through the heat exchanger, a heat exchanging radiator to heat passenger compartment air, a coolant loop through the energy storage to warm the energy storage 170, and any other component on the rail car that would benefit from receiving additional heat from the coolant or heated air from a heat exchanger. When the motor/generator 150 is generating more power than can be stored in the energy storage 170 and used by the auxiliary power 180, the inverter controller 160 can switch the excess power to the braking resistors to heat the circulating coolant. This may occur when the braking regeneration electromagnetic braking is used rather than add wear to the normal friction brakes. The braking resistors 190 may also be heated by the energy storage 170 and used to supply heat via the circulating fluid to a heat exchanger radiator for heating the passenger compartment of the commuter rail car.
The control computer 200 controls operation of the braking regeneration system 100 in the manner described herein. The braking regeneration systems 100 are controlled by the control computer 200 to initiate the acceleration and deceleration modes without lurching the rail cars 100 and compressing the couplers. Real time onboard sensors along with train communications provide input that is processed by processor(s) of the control computer 200 using the computer control algorithms related to applying power or drag to the consist.
The braking regeneration system 100 will now be described during deceleration and acceleration of the consist.
On deceleration, the generator 150 puts a drag on the axle 120 to slow down the rail car 110. System controls prevent the rail cars 110 from abruptly compressing and extending the couplers. The individual rail cars 110 have their systems activated in an in-line or series configuration, one at a time, to prevent lurching. The independent control system may be transparent to the remainder of the consist or may operate as an integrated control system with other cars of the consist. Below a minimum speed, for example 3 mph, the braking regeneration system is turned off and the standard friction brake system is applied to stop the train.
The energy captured from deceleration would, in turn, be fed through the inverter/controllers 160 and into the nickel metal hydride (NiMH) battery energy storage system 170. The charge and discharge levels of the nickel metal hydride (NiMH) battery energy storage system 170 may be limited to extend the cycle life of the energy storage system 170. Ultracapacitors lack sufficient energy storage for this application. However, in an embodiment of the invention, an ultracapacitor pack is incorporated with the battery pack to protect and extend the life of the battery pack. Other types of energy storage, either singly or in combinations, can replace or be added to batteries and/or ultracapacitors.
On acceleration, the recycled stored energy is consumed as the motor/generators 150 are then configured as electric motors 150 to help the locomotive accelerate the consist. As an example of high power operation, the electric motor/generators 150 operate at least 60 seconds at a 282 kW power level before exhausting the scheduled amount of stored energy. A lower power level for a longer period of time during acceleration puts less stress on the components resulting in lower maintenance costs, increased system life, and improved reliability. The energy management system is designed to have infinite variability of control parameters to provide for optimization of the energy capture and recycle. The power is applied until the approximate 4.8 kWh (on average for this embodiment) are delivered for acceleration.
The performance curves in
The performance is provided by a simulation of a PL42 diesel locomotive with a six car Comet V consist. It is based on test track performance for a 0% grade. The 0% grade assumption is representative of an elevation energy neutral model for two way travel over the route.
The graph shown in
These two graphs demonstrate the unique benefit of the braking regeneration system 100 and the almost infinite flexibility available to optimize energy capture. The backup emergency energy remains available at all times in spite of the energy consumed by acceleration. In addition, the anticipated battery life, due to a reduction in system stress, is increased.
One of the advantages of the braking regeneration system 100 is that it allows the elimination of the emergency power battery system on the rail car along with the battery charger. The braking regeneration system 100 is located under floor, so eliminating the existing emergency power battery system frees up space for the components of the braking regeneration system 100, which may be retrofitted onto existing commuter rail cars 110 (and/or passive rail cars) and/or implemented into the original manufacture of the rail car (and/or passive rail cars) and/or rail car chassis/trucks. The energy storage 170 is managed to guarantee at least two hours of emergency backup energy at any time to comply with the Federal Railway Administration (FRA) regulations. This is done by establishing a depletion point of the energy storage system 170 at a level that insures that the energy storage system 170 will always be able to operate. Present rail cars are marginal or non compliant for providing two hours of emergency backup power when the rail car is just going into revenue service after sitting for a day. The capacity of the energy storage system 170 eliminates any concern about meeting the emergency backup power requirement.
With the amount of onboard energy storage, the braking regeneration system 100 will start up automatically from an overnight layover. Should the energy drop to a minimum threshold, three ways to start up the braking regeneration system 100 include: 1) pull or push the rail car 110 to turn the axles 120 and generators 150, 2) use a Head-end Power (HEP) connection to provide electric power from the auxiliary engine generator in the locomotive, and 3) use a grid-based charger.
The first method is preferred and self managed. At start up, the generators 150 operate while the locomotive is pulling or pushing the rail car 110. The generators 150 place an extra drag on the locomotive but would only be active until the energy storage system 170 was at an operating level ready to accept the first deceleration energy capture. Normally, the first train deceleration would bring the energy storage system 170 to an operating capacity level, preparing it for the next acceleration event. Each deceleration event adds to the energy storage 170 state of charge (SOC) to achieve a full working level.
If desired, the other two methods are available for emergency backup. An HEP approach is similar to the current practice: start up the HEP and let it charge the system. A grid based charger could be used to connect the energy storage system 170 to a wayside power supply.
By way of example but not limitation of other types of passive rail cars, another advantage of implementation of the braking regeneration system 100 on a Comet V commuter rail car is an estimated fuel savings of $22,500 annually and in excess of $675,000 over the 30-year life of the rail car. This is based on the following assumptions: one 125,000 pound rail car generates 4.7 kWh of energy savings per deceleration act from an average speed of 70 mph; assuming that the rail car is in service 320 days out of the year and makes four revenue service trips per day (two AM peak and two PM peak) plus weekend service and holiday service, there are 25,600 energy reclamation opportunities (320 days at four passenger trips a day equates to 1280 trips a year of local service stopping 20 times); 25,600 opportunities at 4.7 kWh per stop per car results in a total recoupable energy level of 120,320 kWh, annual fuel savings would be approximately 9,000 gallons of diesel fuel based on an energy efficiency of 30%; at $2.50 per gallon for diesel fuel, fuel savings would total $22,500 annually and in excess of $675,000 over the 30-year life of the rail car. Since fuel costs generally rise over time, future savings are expected to be even greater than $22,500 annually. An additional benefit associated with the reduction in fuel use would be the reduction in exhaust emissions that the combustion of that fuel would have generated.
Also, by way of example but not limitation of other types of passive rail cars, additional advantages of implementation of the braking regeneration system 100 on a Comet V commuter car include benefits to the subsystems on the rail car. For example, because the recovered energy has been taken away from the generation of heat and wear in the brake system, the brake wear and corresponding maintenance for the brake system is reduced. The rail car decelerates by capturing energy on deceleration, while reducing the burden on the braking system. In hybrid-electric buses that use brake regeneration, brake maintenance intervals have been at least doubled. Therefore, a conservative estimate is that a 50% savings would be realized on the maintenance of the rail car brake system. This would double the current reline interval of the rail car 110 along with the subsequent labor and materials required to perform the reline.
The emergency power system would be the next area of savings. By way of example but not limitation of other types of passive rail cars, the Comet V commuter rail car currently has a 74 volt DC emergency power system and battery charger on board each commuter rail car. Other rail cars may operate their emergency power system at other voltages. This method of generating and storing energy for an emergency application period of up to 2 hours could be completely eliminated from the rail car and would then be incorporated into the energy storage system 170 and the auxiliary power inverter and conditioning module 180. The functions of the battery charger and the battery system are now assumed by the main energy storage 170 and can easily provide the emergency requirements. One clear benefit to this approach would be that the system 100 would be able to easily provide more than the two hours of required run time for the emergency backup at any point in time.
A more advanced potential for savings is the concept that the system 100 could actually be configured to provide adequate power so that each rail car 110 could provide energy for itself, thus, reducing head-end power (HEP) requirements. Under this concept, the braking regeneration energy storage system 100 could provide power for all hotel loads on the rail car 110 including HVAC, lighting and communications. Because the 50 kWh of battery energy storage supplies power to the rail car 110 through the inverter and power conditioning module 180, the HEP requirements are significantly reduced or eliminated. If it is desired to transfer power from the locomotive to the passenger rail car, it can be done through the wheels 130 by using the braking generator 150. This approach would reduce the electrical load and extend the life of the HEP system while saving HEP fuel and reducing diesel engine emissions. Recent locomotive designs have completely eliminated the use of an HEP engine-generator and, instead, operate the HEP generator from a power take off of the main diesel engine of the locomotive. In this type of system the braking regeneration system eliminates the need for the additional generator and could contribute to the reduction in total overall horsepower required of the main diesel engine of the locomotive, thus, further reducing fuel consumption and diesel exhaust emissions.
An alternative embodiment of a braking regeneration system uses hydraulic components where a hydraulic motor/pump replaces the electric motor/generator 150; a hydraulic valve controller replaces the electric inverter switch controller 160; a hydraulic accumulator replaces the energy storage 170; and a hydraulic retarder replaces the braking resistors 190. The hydraulic retarder requires some form of liquid or air heat exchanger to dissipate energy. In its simplest form a hydraulic braking regeneration system is the hydraulic analog of the electric braking regeneration system and is a potentially lower cost alternative to an electric braking regeneration system to save fuel costs. Such systems have been built for medium duty hydraulic truck drive systems.
The amount of energy stored in an accumulator is a function of the accumulator pressure and the volume of fluid stored in the accumulator. The temperature of the system, the type of gas used to pre-charge the system, and the initial pressure of the pre-charge gas can impact the amount of energy stored at a given accumulator pressure. The equation to calculate the energy stored in an accumulator is:
Where: E is the energy stored in the accumulator.
A hydraulic braking regeneration system is potentially less expensive than an electric braking regeneration system, but, depending on the practical limits of the size of the accumulator, may have limited energy storage. In concept, a hydraulic motor generator would replace the auxiliary power inverter 180 to power the auxiliary emergency and accessory electrical loads 210.
With reference to
Railroad operations often use one or more additional diesel electric locomotives to assist the propulsion of freight trains up long grades. At the top of or some point beyond the summit of the grades the locomotives are uncoupled from the train at a switch yard or siding and sent back to the bottom of the grade, where they may be used again for the same purpose with the next freight train requiring assistance.
With reference additionally to
The battery cars 280 and associated electric locomotives 270 of the combinations 260 are strategically placed at railroad grades where they ascend and descend continually with the passing railroad traffic. Additionally or alternatively, only the battery cars 280 are strategically placed at railroad grades where they ascend and descend continually with passing railroad traffic hauled by a diesel electric-powered locomotive that has been configured to accept energy from an energy storage car.
With reference to
With reference to
With reference to
With reference to
With reference to
With reference to
With reference to
GG and GK, “Green Goat,” hybrid-electric rail yard switching locomotives have been built by RailPower Technologies Corporation. These “switchers” have up to 840 kWh of energy storage on-board with maintenance free lead-acid batteries in addition to a 200 to 500 KW diesel generator set. The weight is about 275,000 pounds with an equivalent 2000 horsepower. The inventors have determined that these hybrid locomotives could be used/modified in accordance with the principles of the invention described herein to perform a grade “assist” function.
The following are some sample calculations by the inventors in determining potential energy savings with the present invention.
Equating energy saved to diesel fuel gallons and fuel costs follows below:
Li ion battery energy storage parameters:
Recycling freight train braking energy from downhill grades to use as an assist to the propulsion of freight trains traveling uphill saves a considerable amount of energy compared to using one or more additional diesel electric-powered locomotives to assist the propulsion of freight trains up long grades. Rather than using one or more diesel electric-powered locomotives to assist moving the train uphill, the one or more multi mode diesel electric-powered locomotives with one or more attached energy storage cars assist moving the train uphill. The energy storage car contains electrical energy storage, e. g., a battery pack, which is charged by the electric motor/generators of the locomotive or other cars from a previous descent of the grade. At the top of the grade the additional electric locomotives with attached energy storage cars are coupled to a descending train to provide dynamic braking and charge the energy storage.
By way of example, but not limitation, one typical railroad grade extends from San Bernardino, Calif. (elevation 1118 feet) up the El Cajon Pass Summit (elevation 3855 feet), for an elevation change of 2735 feet, and back down to the switch yard at Barstow, Calif. (elevation 2163 feet). The 2735 foot elevation descent from the summit to the switch yard at San Bernardino represents about 207 kWh of energy for a loaded freight car of 200,000 pounds.
Therefore, 20 rail cars descending the grade have about 4.1 megawatt hours (MWh) of energy. For a long consist of 100 rail cars the energy is about 20.6 MWh not including the locomotives.
Assuming that 50% of the energy is recoverable from dynamic braking regeneration capture and recycling, about 103 kWh of useable energy storage is required per rail car. Operating at 50% depth of discharge (DoD) to get 12,000 life cycles the energy storage requirement is 206 kWh per 200,000 pound freight car. From the Lithium-ion battery parameters the battery pack characteristics are:
At 80% battery efficiency each of the above cycles saves 81.6 kWh. At a diesel fuel cost of $3.00/gallon, the break even point ($145,436/$3.00=48,479) is a fuel savings of 48,479 gallons diesel or 485 MWh. At 81.6 kWh per cycle the break even point is 5944 battery energy storage cycles. This is well within the expected 12,000 life cycles and suggests that another $148,000 of diesel fuel savings (at $3.00/gallon) would accumulate before battery replacement to help pay for the cost of installing the batteries, motor/generators, and control equipment. With the anticipated increasing future fuel prices and decreasing future energy storage prices the projected savings increases beyond these estimates. However, if the energy storage was placed on each individual rail car, thereby adding significant weight to the rail car, this savings is achieved only if the individual rail car experiences thousands of life cycles within the 10 year calendar life of the batteries.
The energy savings can be more cost effectively achieved when the battery cars and associated electric locomotives (or the battery cars only) are strategically placed at railroad grades where they ascend and descend continually with the passing railroad traffic. For the above El Cajon Summit example, one method is to have an energy storage car for every 20 freight cars. The required energy storage characteristics are 20 times those for a single car:
Similar to the El Cajon Pass summit grade described above, most grade applications will experience 1˝ to 2 cycles per round trip because of the high point (summit) in the middle and lower points at each of the rail switch yards. Therefore, estimating 1000 cycles per year, the fuel savings would pay for the batteries in less than 6 years and at the end of 12 years (12,000 cycle life of the batteries) there would be an extra fuel savings of $2.96 million that would have paid back more than the capital cost of building the energy storage freight car. With the anticipated increasing fuel costs and decreasing energy storage costs the extra fuel savings will continue to increase. Extending this projection from year 13 to end of year 36 (estimated rail car life) results in an estimated $6 million diesel fuel cost savings ($250,000 per year average over years 13 to 36) per energy storage rail car beyond the capital costs and the energy storage costs. The estimated energy savings is 1632 MWh per energy storage rail car per year, or 163,200 gallons of diesel fuel per energy storage rail car per year.
For fewer charge/discharge cycles per year or for different energy storage life characteristics, the size of the energy storage can be decreased for a greater DoD such that the energy storage cycle life and the energy storage calendar life match, thus saving the overall energy storage costs while providing the required energy storage. Alternatively, the energy storage can be sized for a greater or lesser number of rail cars than the 20 rail cars described in the example above.
The computer system 550 preferably includes one or more processors, such as processor 552. Additional processors may be provided, such as an auxiliary processor to manage input/output, an auxiliary processor to perform floating point mathematical operations, a special-purpose microprocessor having an architecture suitable for fast execution of signal processing algorithms (e.g., digital signal processor), a slave processor subordinate to the main processing system (e.g., back-end processor), an additional microprocessor or controller for dual or multiple processor systems, or a coprocessor. Such auxiliary processors may be discrete processors or may be integrated with the processor 552.
The processor 552 is preferably connected to a communication bus 554. The communication bus 554 may include a data channel for facilitating information transfer between storage and other peripheral components of the computer system 550. The communication bus 554 further may provide a set of signals used for communication with the processor 552, including a data bus, address bus, and control bus (not shown). The communication bus 554 may comprise any standard or non-standard bus architecture such as, for example, bus architectures compliant with industry standard architecture (“ISA”), extended industry standard architecture (“EISA”), Micro Channel Architecture (“MCA”), peripheral component interconnect (“PCI”) local bus, or standards promulgated by the Institute of Electrical and Electronics Engineers (“IEEE”) including IEEE 488 general-purpose interface bus (“GPIB”), IEEE 696/S-100, and the like.
Computer system 550 preferably includes a main memory 556 and may also include a secondary memory 558. The main memory 556 provides storage of instructions and data for programs executing on the processor 552. The main memory 556 is typically semiconductor-based memory such as dynamic random access memory (“DRAM”) and/or static random access memory (“SRAM”). Other semiconductor-based memory types include, for example, synchronous dynamic random access memory (“SDRAM”), Rambus dynamic random access memory (“RDRAM”), ferroelectric random access memory (“FRAM”), and the like, including read only memory (“ROM”).
The secondary memory 558 may optionally include a hard disk drive 560 and/or a removable storage drive 562, for example a floppy disk drive, a magnetic tape drive, a compact disc (“CD”) drive, a digital versatile disc (“DVD”) drive, etc. The removable storage drive 562 reads from and/or writes to a removable storage medium 564 in a well-known manner. Removable storage medium 564 may be, for example, a floppy disk, magnetic tape, CD, DVD, etc.
The removable storage medium 564 is preferably a computer readable medium having stored thereon computer executable code (i.e., software) and/or data. The computer software or data stored on the removable storage medium 564 is read into the computer system 550 as electrical communication signals 578.
In alternative embodiments, secondary memory 558 may include other similar means for allowing computer programs or other data or instructions to be loaded into the computer system 550. Such means may include, for example, an external storage medium 572 and an interface 570. Examples of external storage medium 572 may include an external hard disk drive or an external optical drive, or and external magneto-optical drive.
Other examples of secondary memory 558 may include semiconductor-based memory such as programmable read-only memory (“PROM”), erasable programmable read-only memory (“EPROM”), electrically erasable read-only memory (“EEPROM”), or flash memory (block oriented memory similar to EEPROM). Also included are any other removable storage units 572 and interfaces 570, which allow software and data to be transferred from the removable storage unit 572 to the computer system 550.
Computer system 550 may also include a communication interface 574. The communication interface 574 allows software and data to be transferred between computer system 550 and external devices (e.g. printers), networks, or information sources. For example, computer software or executable code may be transferred to computer system 550 from a network server via communication interface 574. Examples of communication interface 574 include a modem, a network interface card (“NIC”), a communications port, a PCMCIA slot and card, an infrared interface, and an IEEE 1394 fire-wire, just to name a few.
Communication interface 574 preferably implements industry promulgated protocol standards, such as Ethernet IEEE 802 standards, Fiber Channel, digital subscriber line (“DSL”), asynchronous digital subscriber line (“ADSL”), frame relay, asynchronous transfer mode (“ATM”), integrated digital services network (“ISDN”), personal communications services (“PCS”), transmission control protocol/Internet protocol (“TCP/IP”), serial line Internet protocol/point to point protocol (“SLIP/PPP”), and so on, but may also implement customized or non-standard interface protocols as well.
Software and data transferred via communication interface 574 are generally in the form of electrical communication signals 578. These signals 578 are preferably provided to communication interface 574 via a communication channel 576. Communication channel 576 carries signals 578 and can be implemented using a variety of wired or wireless communication means including wire or cable, fiber optics, conventional phone line, cellular phone link, wireless data communication link, radio frequency (RF) link, or infrared link, just to name a few.
Computer executable code (i.e., computer programs or software) is stored in the main memory 556 and/or the secondary memory 558. Computer programs can also be received via communication interface 574 and stored in the main memory 556 and/or the secondary memory 558. Such computer programs, when executed, enable the computer system 550 to perform the various functions of the present invention as previously described.
In this description, the term “computer readable medium” is used to refer to any media used to provide computer executable code (e.g., software and computer programs) to the computer system 550. Examples of these media include main memory 556, secondary memory 558 (including hard disk drive 560, removable storage medium 564, and external storage medium 572), and any peripheral device communicatively coupled with communication interface 574 (including a network information server or other network device). These computer readable mediums are means for providing executable code, programming instructions, and software to the computer system 550.
In an embodiment that is implemented using software, the software may be stored on a computer readable medium and loaded into computer system 550 by way of removable storage drive 562, interface 570, or communication interface 574. In such an embodiment, the software is loaded into the computer system 550 in the form of electrical communication signals 578. The software, when executed by the processor 552, preferably causes the processor 552 to perform the inventive features and functions previously described herein.
Various embodiments may also be implemented primarily in hardware using, for example, components such as application specific integrated circuits (“ASICs”), or field programmable gate arrays (“FPGAs”). Implementation of a hardware state machine capable of performing the functions described herein will also be apparent to those skilled in the relevant art. Various embodiments may also be implemented using a combination of both hardware and software.
Furthermore, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and method steps described in connection with the above described figures and the embodiments disclosed herein can often be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the invention. In addition, the grouping of functions within a module, block, circuit or step is for ease of description. Specific functions or steps can be moved from one module, block or circuit to another without departing from the invention.
Moreover, the various illustrative logical blocks, modules, and methods described in connection with the embodiments disclosed herein can be implemented or performed with a general purpose processor, a digital signal processor (“DSP”), an ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
Additionally, the steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium including a network storage medium. An exemplary storage medium can be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can also reside in an ASIC.
The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly limited by nothing other than the appended claims.